The three-dimensional magnetic structure and reversalmechanism of patterned Co/Pt multilayers, were imaged using complementary Lorentz transmission electron microscopy (LTEM) (in-plane component) and magnetic transmission x-ray microscopy (M-TXM) (perpendicular magnetization). The Co/Pt films with perpendicular anisotropy were patterned by ion irradiation through a stencil mask to produce in-plane magnetization in the irradiated regions. The boundaries of the patterns, defined by the transition from out-of-plane to in-plane magnetization, were found to be determined by the stencil mask, whilst the scale of the magneticreversal by the physical microstructure. The nucleation fields were substantially reduced to 50 Oe for the in-plane regions and 1 kOe for the perpendicular regions, comparing to 4.5 ...
This review of methods and designs of transducers for nondestructive determination of the magnitude and nature of the anisotropy of magnetic properties (permeability, induction, coercive force, energy loss due to magnetizationreversal) in local portions of ferromagnetic sheet and, in some cases, in individual parts of products. The need to measure the anisotropy is considered for two angles: for the case when the anisotropy is due to the crystallographic texture and determines the main operating characteristics of widely used sheet such as electrical steel and automobile body sheet, and for crystallographically isotropic materials, in which the anisotropy of magnetic properties as a result of mechanical stresses is a measure for determining the internal stresses.
The switching behavior of magnetic patterns prepared by ion irradiation was investigated. Co/Pt multilayers with perpendicular anisotropy and large out-of-plane coercivities 5-6 kOe were grown on electron transparent SiN windows. Regularly spaced 1 micron sized regions, were magnetically pattered via ion beam irradiation through a stencil mask. Lorentz TEM was used to observe in-situ magnetizationreversal processes of irradiated regions under well-defined applied magnetic fields. When the in-plane field was increased, domain wall motion was observed, resulting in the alignment of the patterns with the direction of the applied field. The switching mechanism of the in-plane patterns was by domain wall motion.
Magnetic imaging in the transmission electron microscope (TEM) has been used to examine submicron elements with the aim of discovering down to what element size complex domain patterns can form. The elements were squares, circles, triangles, and pentagons in the size range 100{endash}500 nm and were made from 36 nm Co films or 8 nm Ni{sub 80}Fe{sub 20} (NiFe) with in-plane magnetization. The magnetic domain structures in these elements were imaged at high resolution using the differential phase contrast imaging mode in a TEM. Nonuniform magnetization structures were seen in the images. Vortices were present at remanence in all shapes of 36-nm-thick Co elements down to 100 nm size and in circular NiFe elements down to 116 nm diameter. Triangular NiFe elements did not have a vortex state at remanence, instead the magnetization curved round within the element but did not achieve ...
Several recent experiments on micro- (or nano-) structured samples of ferromagnetic materials are introduced. Magnetizationreversal phenomena are investigated on submicron wire samples of trilayer structure using the giant magnetoresistance effect. Domain wall movements are sensitively monitored by resistivity measurements and the velocity of propagation is determined. The contribution of domain wall to the resistivity is argued from the results on artificially designed samples of a spring-magnet system. In circular dots of permalloy, the existence of vortex magnetization is confirmed and the reversal of the vortex core magnetization is studied from magnetic force microscopy measurements. (author)
The method of proton magnetic resonance (PMR) has been used to study the mechanism of reaction of complexing of paramagnetic Pr/sup 3 +/ ion with ethylenediaminetetra acetic acid (EDTA). The influence of medium acidity (pH5-12), EDTA/Pr ratio varying from 1 to 50, Pr/sup 3 +/ ion concentration (from 5x10/sup -3/ to 3x10/sup -1/ g-ion/l) and temperature (8-98 deg C) on chemical shifts and broadening of signals of EDTA molecule protons is investigated. Data on ratio of components, coordination and stability of forming complexes are obtained. The existence of two types of complexes with the Pr/EDTA ratio equal to 1:1 and 1:2 has been found. Equimolecular complex (1:1) is stable all over the studied temperature interval in contrast to the complex 1:2 for which at 50 deg C fast extrasphere exchange (Pr EDTA)EDTA * + EDTA/sup 0/ reversible (PrEDTA)EDTA/sup 0/ + EDTA * is observed, while at t=98 deg C intrasphere exchange ...
Generation of replicative defective viruses is frequently observed during viral infections. We now report that encapsidation and reverse transcription of spliced viral RNA is an additional mechanism...Full Text Available
Age-related alterations in the cellular composition of the B lineage are a major cause of the poor antibody response to vaccination and to infectious agents among the elderly population. The mechanisms...Full Text Available
In this paper, we report on the analysis of reverse flow in inverted U-tubes of a steam generator under natural circulation condition. The mechanism of reverse flow in inverted U-tubes of the steam generator with natural circulation is graphically analyzed by using the full-range characteristic curve of parallel U-tubes. The mathematical model and numerical calculation method for analyzing the reverse flow in inverted U-tubes of the steam generator with natural circulation have been developed. The reverse flow in an inverted U-tube steam generator of a simulated pressurized water reactor with natural circulation in analyzed. Through the calculation, the mass flow rates of normal and reverse flows in individual U-tubes are obtained. The predicted sharp drop of the fluid temperature in the inlet plenum of the steam generator due to reverse ...
We demonstrate reversible movement of (1/2)[110](110) dislocation loops generated from nanodisturbances in a #beta#-titanium alloy. High resolution transmission electron microscope observations during an in situ tensile test found three reversible deformation mechanisms, nanodisturbances, dislocation loops and martensitic transformation, that are triggered in turn with increasing applied stress. All three mechanisms contribute to the nonlinear elasticity of the alloy. The experiments also revealed the evolution of the dislocation loops to disclination dipoles that cause severe local lattice rotations.
Field reversed configuration (FRC) is a prospective high ? magnetic system for high efficiency D- 3He fusion reactor. Self-consistent FRC plasma profiles and static electric field for reactor calculations are discussed in framework of the model including flow equilibrium and collisionless transport equations. The extrapolations to reactor regimes of plasma confinement scaling laws are considered.
The method of double microwave--radio-frequency resonance has been used to obtain spectra of the 2/sub 11/reverse arrow2/sub 12/ and 3/sub 21/reverse arrow3/sub 22/ transitions in HCOOD, DCOOH, and HCOOH molecules. The constants of the quadrupole bond of the deuterons have been determined, magnetic interactions being taken into acocunt. A comparison with results of previous studies is given.
The reversion time migration, as one of reflection seismic prospecting migration, reverse propagates a wave equation by reverse promoting the differential time, and conducts the migration. The method has such merits as no limit to the inclined angle of a reflection, correspondence to a complex topography etc. And, there is a finite difference time domain (FDTD) that uses the Maxwell equation as it is and makes a difference approximation in the methods differentiating and resolving electro-magnetic fields. It is also possible to apply the reverse time migration onto it. In this speech, using an explosive reflection face, a slope 2 layer structure and models of its reflection points are synthesized by a ground penetrating radar using the FDTD, and reverse time migration is conducted. As a result, it is clarified that the reverse time migration ...
It is shown that plasma viscosity does not influence the magnetic island rotation directly. Nevertheless, it leads to nonstationarity of the plasma velocity. This nonstationarity is the reason of the viscosity effect on island rotation. (author)
Annual averages of the diurnal variation in cosmic ray intensity from neutron monitors in Deep River and Oulu and underground muon telescopes in Bolivia and at Embudo and Socorro, New Mexico, have been determined as a function of the sense of the interplantary magnetic field for the years 1965--1975. These data point to a cosmic ray density gradient, perpendicular to the ecliptic plane, pointing southward prior to 1969 and changing to a northward pointing gradient after the reversal of the sun's polar magnetic field in 1969--1971. This result supports numerical calculations for the prereversal and postreversal field configurations at intermediate and high cosmic ray rigidities.
The magnetoresistance in an FeNi submicron-structure comprising two wires of 80 and 200 nm in width connected in series was measured at 77 K. When the external magnetic field was applied parallel to the wire axis, two switching fields corresponding to the distinct coercive force of the two wires were observed. When the external magnetic field was applied at an angle of {theta}>30 deg. to the wire axis one switching field was observed, indicating simultaneous magnetizationreversal in both wires. This indicates that the domain-wall trapping around the joint can be controlled systematically in terms of the direction of the external magnetic field.
Although the subtrate binding properties of adenylate kinase (AK) have been studied extensively by various biochemical and biophysical techniques, it remains controversial whether uncomplexed adenosine 5'-triphosphate (ATP) binds to the adenosine 5'-monophosphate (AMP) site of AK. The authors present two sets of experiments which argue against binding of ATP to the AMP site. (a) /sup 31/P nuclear magnetic resonance titration of ATP with AK indicated a 1:1 stoichiometry on the basis of changes in coupling constants and line widths. This ruled out binding of ATP to both sites. (b) ATP and MgATP were found to behave similarly by protecting AK from spontaneous inactivation while AMP showed only a small degree of protection. Such inactivation could also be protected or reversed by dithioerythritol and is most likely due to oxidation of sulfhydryl groups, one of which (cysteine-25) is located near the MgATP site. The results support ...
Cycling parameters (reversible specific capacity, first-cycle coulombic efficiency, accumulated irreversible capacity, and reversible capacity retention) of hybrid electrodes based on mechanical mixtures of a silicon nanopowder with KS6 and MAG-20 synthetic graphites and binders of varied nature were subjected to an integrated analysis in comparison with graphite electrodes.
Magnetic drug targeting, using core-shell magnetic carrier particles loaded with anti-cancer drugs, is an emerging and significant method of cancer treatment. Gold shell-iron core nanoparticles (Fe@Au) were synthesized by the reverse micelle method with aqueous reactants, surfactant, co-surfactant and oil phase. XRD, XPS, TEM and magnetic property measurements were utilized to characterize these core-shell nanoparticles. Magnetic measurements showed that the particles were superparamagnetic at room temperature and that the saturation magnetization decreased with increasing gold concentration. The anti-cancer drug doxorubicin (DOX) was loaded onto these Fe@Au nanoparticle carriers and the drug release profiles showed that upto 25% of adsorbed drug was released in 80 h. It was found that the amine (-NH2) group of DOX binds to the gold shell. An in vitro apparatus ...
Monte Carlo calculations of proton irradiation of permanent magnets for the TRADE experiment have been performed. An irradiation dose of about 4´106 Gy/yr/mA has been estimated due to beam losses in normal operating conditions. Existing experimental results indicate that this irradiation level may induce a considerable demagnetization: in fact, a dose of 6´107 Gy induces a remanence loss of 0.3 % on samples of Sm2Co17 magnets, which are the most resistant type. More detailed calculations with the final design of the magnets and of the beam line are suggested, to determine if the irradiation levels allowed a reliable operation of the permanent magnets for the entire duration of the TRADE experiment. Damage and gas production rates have also been calculated; the values obtained are very low, thus confirming that the demagnetization process is in great part reversible.
We have investigated via SQUID magnetometry and polarised neutron reflectivity the exchange-bias effect in CoO/Co sputtered multilayers. In particular, we studied the magnetisation reversal and the time relaxation of the exchange-bias field close to the coercive field H{sub c1}. Neutron intensities of all four cross sections (I++, I+-, I-+, I-) were recorded at the position of the first multilayer Bragg peak while scanning the magnetic field. From such scans we infer that the magnetisation reversal for the ascending as well as for the descending branch of the magnetic hysteresis occurs not by in-plane rotation but through domain-wall movements. The exchange-bias field, H{sub EB}, is strongly affected by thermal fluctuations. H{sub EB} decreases, following an exponential decay function with a half-life time of about 580 s at T=240 K. (orig.)
A generic reactor model is used to examine the economic viability of electricity generation by magnetic fusion. The simple model uses components which are representative of those used in previous reactor studies of deuterium-tritium burning tokamaks, stellarators, bumpy tori, reverse field pinches and tandem mirrors. Conservative costing assumptions are made. The generic reactor is not a tokamak but rather it is intended to emphasize what is common to all magnetic fusion reactors. The reactor uses a superconducting toroidal coil set to produce the dominant magnetic field. To this extent it is a less good approximation to systems, such as the reversed field pinch in which the main field is produced by a plasma current. The main output of the study is the cost of electricity as a function of the weight and size of the fusion core - blanket, shield, structure and coils. The model shows ...
Closing and breaking of current in microsecond megaampere plasma opening switches are considered. Conductivity current scaling in the switch due to plasma acceleration by a magnetic piston is discussed and compared with experimental data. Two ways of determining the width of a current channel are taken up. This channel results from the diffusion of the magnetic field in the plane of the piston followed by the convective ejection of the field frozen in the accelerated plasma flow behind the shock wave into the bridge. Based on experimental data, a scaling law for the voltage on the switch according to the switch parameters is derived. The problem of reverse closing, which limits the efficiency of storage energy extraction into the load, is considered
We describe a class of organic molecular magnets based on zwitterionic molecules (betaine derivatives) possessing donor, p bridge, and acceptor groups. Using extensive electronic structure calculations we show the electronic ground-state in these systems is magnetic. In addition, we show that the large energy differences computed for the various magnetic states indicate a high Neel temperature. The quantum mechanical nature of the magnetic properties originates from the conjugated p bridge (only p electrons) in cooperation with the molecular donor-acceptor character. The exchange interactions between electron spin are strong, local, and independent on the length of the p bridge.
The homogeneity of the magnetic field in the LHC dipoles strongly depends on the correct position of the superconducting cables: this is related to the quality of the dipole components, such as the dimension of the coil spacers (copper wedges), of the cable and of the collars. The performance in operational conditions is also affected by the magnetization of the cables. In this work, we analyse the measurements of these quantities during the production of the 1276 LHC dipoles, their trends, and the relation to the measured magnetic field. A novel mtehod to locate electrical shorts based on the analysis of magnetic measurements is also presented, and applications to 15 dipoles reascued during the production is given.
The phenomenological description of the giant magnetoresistance effect as well as discussion of the requirements which must be fulfilled in giant magnetoresistance thin film structures are given in the first part of our review. In the second part the magnetizationreversal and giant magnetoresistance effect of antiferromagnetically coupled multilayers, spin Valve and pseudo-spin valve thin film structures are explained. For these structures we also discuss the influence of the structure defects such as surface roughness and pinholes on the giant magnetoresistance effect. (author)
Ultrafine particles of Co-P were synthesized by direct ball milling of Co and P powders and also investigated as a reversible hydrogen storage electrode material. The electrochemical results demonstrated that the reversible charge-discharge capacity of the Co-P electrode can reach more than 300mAh/g. In addition, the cycling ability and high rate capability of the Co-P electrode are excellent with only 5% capacity decay after 100 cycles at a high rate of 300mA/g. The temperature-programmed desorption measurements (TPD) of the Co-P electrode revealed that the charge and discharge reactions of the Co-P electrode proceeds predominantly through electrochemical hydrogen storage mechanism and the electrooxidation of cobalt contributes only a negligible part to the reversible electrochemical capacity. (author)
The previously unknown property of the optical speckle pattern reported. The interference of a speckle with the counterpropagating phase-conjugated (PC) speckle wave produces a randomly distributed ensemble of a twisted entities (ropes) surrounding optical vortex lines. These entities appear in a wide range of a randomly chosen speckle parameters inside the phase-conjugating mirrors regardless to an internal physical mechanism of the wave-front reversal. These numerically generated interference patterns are relevant to the Brillouin PC mirrors and to a four-wave mixing PC mirrors based upon laser trapped ultracold atomic cloud.
Electrochemical techniques have been used to study the reversible insertion of sodium into hard-carbon host structures at room temperature. In this paper the authors compare these results with those for lithium insertion in the same materials and demonstrate the presence of similar alkali metal insertion mechanisms in both cases. Despite the gravimetric capacities being lower for sodium than lithium insertion, the authors achieved a reversible sodium capacity of 300 mAh/g, close to that for lithium insertion in graphitic carbon anode materials. Such materials may therefore be useful as anodes in rechargeable sodium-ion batteries.
Magnetic properties of layer ferromagnets against the thickness are investigated. Two new compounds served for studies: Bisub(6)Tisub(2)Nbsub(0,5)Fesub(2,5)Osub(18) and Bi_7Ti_3Fe_3O_2_1. The Moessbauer effect and the magnetic susceptibility measurements were applied in the experiment. The Faraday method was used in magnetic measurements in fields from 1 to 9,5 kOe. The results of Moessbauer measurements show that temperature dependence of the spectra is typical for compounds with superparamagnetic properties. The magnetic fields Hsub(n) on Fe"5"7 nuclei in Bisub(6)Tisub(2)Nbsub(0,5)Fesub(2,5)Osub(18) and Bi_7Ti_3Fe_3O_2_1 are similar and equal to 520+-10 kOe. Therefore it may be concluded that relaxation times of nuclear spins in these compounds are equal or close to each other. The lines of quadrupole splitting appear in spectra together at 20 K. The results of magnetic ...
Purpose - The purpose of this paper is to investigate the accuracy of different force calculation methods and their impact on mechanical deformations. For this purpose, a micrometer scaled actuator is considered, which consists of a micro-coil and of a permanent magnet (PM) embedded in a deformable elastomeric layer. Design/methodology/approach - For the magnetic field evaluation a hybrid numerical approach (finite element method/boundary element method (FEM/BEM) coupling and a FEM/BEM/Biot-Savart approach) is used, whereas FEM is implemented for the mechanical deformation analysis. Furthermore, for the magneto-mechanical coupling several force calculation methods, namely the Maxwell stress tensor, the virtual work approach and the equivalent magnetic sources methods, are considered and co...
Pacini (1973) has considered basic theoretical expectations regarding the magnetic dipole radiation and unipolar induction of pulsars, taking into account observational results. The present investigation is concerned with the difference between the two braking mechanisms. Attention is also given to a statistical study involving a comparison of the two braking mechanisms with observations. The study makes use of the observational data for the distribution of apparent beamwidth, and a geometrical method. The obtained results agree with the theory of magnetic dipole radiation.
A previous study described the basic theoretical expectations of the magnetic dipole radiation and unipolar induction of pulsars and presented observational results. This paper further discusses the difference between the two braking mechanisms and analyses the results of a statistical study through observed data of apparent beamwidth's distributions and a geometrical method. The theory of magnetic dipole radiation of pulsars agrees with the observations. Unipolar induction as a braking mechanism is not consistent with the observations.
Ge pre-amorphisation step is used to reduce the high diffusivity and the transient-enhanced diffusion of boron implanted in silicon. The aim of the process is to obtain shallow P{sup +}N junctions. The pre-amorphisation step was performed under different conditions (in ambient temperature and in nitrogen). Following the rapid thermal annealing step, end of range (EOR) defects appear at the amorphous-crystalline interface. These defects could influence the electrical characteristics of the P{sup +}N junctions. An experimental study concerning three samples has been performed without and under a magnetic field of 800 G. The magnetic susceptibility was essentially observed in the case of the reverse current. The impact of the magnetic field, studied by varying the sample temperature, permits us to show an increase of the magnetic susceptibility when the defects present in such ...
Ge pre-amorphisation step is used to reduce the high diffusivity and the transient-enhanced diffusion of boron implanted in silicon. The aim of the process is to obtain shallow P"+N junctions. The pre-amorphisation step was performed under different conditions (in ambient temperature and in nitrogen). Following the rapid thermal annealing step, end of range (EOR) defects appear at the amorphous-crystalline interface. These defects could influence the electrical characteristics of the P"+N junctions. An experimental study concerning three samples has been performed without and under a magnetic field of 800 G. The magnetic susceptibility was essentially observed in the case of the reverse current. The impact of the magnetic field, studied by varying the sample temperature, permits us to show an increase of the magnetic susceptibility when the defects present in such structures are ...
The authors have performed a preliminary design for a persistent GHz NMR magnet at 23.5 T and 1.8 K operating conditions. In this paper the authors shall address the issues of realistic conductor selection, the coil design, the magnetic and mechanical analysis of the coil, and the required field uniformity. In addition, they shall describe the GHz magnet cryostat with a practical 1.8 K J-T refrigerator system. Finally vibration isolation system and field shield design and its associated field harmonics will be analyzed.
The effect of 50 Hz and 60 Hz (frequencies of current distribution) and 20 kHz to 50 kHz (frequencies of induction cooktop) magnetic interference on implanted pacemakers have been assessed with the present generation of device technology. Sixty patients implanted in 1998 and 1999 with dual chamber pacemakers from 9 different manufacturers were monitored with telemetry while passing through, and standing between a system of two coils. They generated a 50 Hz or a 60 Hz magnetic field at 50 microT. Then, patients used a cooktop at different power. The recordings were made with the standard setting of "medically correct" sensing parameters chosen for the patients. Then pacemakers were reprogrammed to the unipolar mode, with the highest atrial (A) and ventricular (V) sensitivity that did not induce muscular inhibition while moving. Between each exposure (50 Hz, 60 Hz or 20 kHz to 50 kHz), the pacemaker programmation was controlled. At the end of the ...
Current multi-scale computational models of ventricular electromechanics describe the full process of cardiac contraction on both the micro- and macro- scales including: the depolarization of cardiac cells, the release of calcium from intracellular stores, tension generation by cardiac myofilaments, and mechanical contraction of the whole heart. Such models are used to reveal basic mechanisms of cardiac contraction as well as the mechanisms of cardiac dysfunction in disease conditions. In this paper, we present a methodology to construct finite element electromechanical models of ventricular contraction with anatomically accurate ventricular geometry based on magnetic resonance and diffusion tensor magnetic resonance imaging of the heart. The electromechanical model couples detailed repres...
Anisotropic Nd{endash}Fe{endash}B magnet powders can be produced by the hydrogenationdecomposition-desorption-recombination (HDDR) process from Nd{endash}Fe@ xnB{endash}Co{endash}M ({ital M}=Ga, Zr, Nb, Hf, and Ta) alloys. The present status of those HDDR powders and the bonded magnets made from them are reviewed with regards to the powder particle size dependence of their magnetic properties, their magnetic thermal stability, and their magnetization behavior. The results of a mechanistic study on the recombination step are also presented. The magnetic properties of the anisotropic HDDR powder depend relatively little on the powder particle size. Bonded magnets with a density of {approximately}6.20 g/cm{sup 3} and a BH{sub max} of 18.5{endash}20.5 MGOe can be produced from anisotropic HDDR powders with particle sizes of below 300 {mu}m diam. ...
Silicon/carbon composite anode materials were prepared by pyrolyzing the phenol-formaldehyde resin (PFR) mixed with silicon and graphite powders. Scanning electron microscopic (SEM) observation showed that the morphology stability of the composite electrodes can be retained during cycling. A structure evolution mechanism is proposed to illuminate the enhancement of cycleability of the composite electrode. The composite used as anode material for lithium ion batteries possesses a reversible capacity of over 700 mAh/g.
It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H(+M) reversible arrow HOSO(+M), HOSO + H/OH reversible arrow SO2 + H-2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find that the interaction of SO, with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H-2, as major products of ...
The current paper continues the analysis of a completely novel method of fluid manipulation technology in micro-fluidics systems, inspired by nature, namely by the mechanisms found in ciliates. More information on this subject can be found at http://www.hitech-projects.com/euprojects/artic/. In order to simulate the drag forces acting on an array of artificial cilia, we have developed a computer code that is based on fundamental solutions of Stokes flow in a semi-infinite domain. The actuation mechanism consists of a bi-directional rotating excitation magnetic field. The magnetization induced by the magnetic field was calculated in a separate routine based on the Integral Nonlinear Equations Approach with 1D discretization of wire (cilium). Time averaged x-coordinate mass flow rates, strea...
MAGNETIC FORMING .............. MAGNETIC INDUCTION ............ MAGNETIC MATERIALS ............ MAGNETIC MEASUREMENT .......... MAGNETIC PERMEABILITY . ...
The signature of the negative snakes from the soft X-ray cameras is very similar to the more usual snakes except that the localised region of the snake has, compared with its surroundings, decreased rather than increased emission. Circumstances where negative snakes have been seen are reviewed. The negative snake appears as a region of increased resistance and of increased impurity density. The relationship between the shear and the current perturbation is shown, and it seem probable that the magnetic shear is reversed at the point of the negative snake, i.e. that q is decreasing with radius. 6 refs., 6 figs.
In this paper we demonstrate the electrodeposition of nickel, a common ferromagnetic material, in various magnetically desirable shapes including nanowires, nanoparticles and highly faceted shells. In order to obtain three dimensional mesostructures, the electrochemical deposition of nickel was performed on highly oriented pyrolytic graphite (HOPG) under different electrolyte composition and deposition potential conditions. Under potentiostatic deposition at one distinct potential negative with respect to the reversible potential of nickel, three stages of nucleation and growth take place leading to a complex morphology of deposits. However, dual-pulse potential deposition and electrodeposition in low pH solutions causing hydrogen evolution, lead to nickel deposits in the form of nanowires...
A new method for kinetic experiments with neutrons is described. This method combines the conventional triple-axis neutron spectroscopy with relaxation-type experiments. Whereas the former method yields information about the microscopic dynamics of solids, the latter provides macroscopic relaxation times. The combination of both methods allows to determine the microscopic mechanism of relaxation processes. The time-resolved triple-axis spectroscopy is limited to reversible processes and to time scales from 10"-"3 to 10"4 s. Typical applications are the kinetics of phase transformations (structural and dynamical changes), kinetics of domain distributions, kinetics of (spinodal) decomposition, reversible solid state reactions, time-dependent occupation of phonon states or phonon lifetimes. (orig.).
SnO2/graphene nanocomposites have been fabricated by a simple chemical method. In the fabrication process, the control of surface charge causes echinoid-like SnO2 nanoparticles to be formed and uniformly decorated on the graphene. The electrostatic attraction between a graphene nanosheet (GNS) and the echinoid-like SnO2 particles under controlled pH creates a unique nanostructure in which extremely small SnO2 particles are uniformly dispersed on the GNS. The SnO2/graphene nanocomposite has been shown to perform as a high capacity anode with good cycling behavior in lithium rechargeable batteries. The anode retained a reversible capacity of 634 mA?h?g?1 with a coulombic efficiency of 98% after 50 cycles. The high reversibility can be attributed to the mechanical buffering by the GNS against...
Over the last year-and-a-half, several 4-cm-aperture, 17-m-long dipole magnet prototypes were built by Brookhaven National Laboratory (BNL) under contract with the Superconducting Super Collider (SSC) Laboratory. These prototypes are the last phase of a half-decade-long R D program, carried out in collaboration with Fermi National Accelerator Laboratory and Lawrence Berkeley Laboratory, and aimed at demonstrating the feasibility of the SSC main ring dipole magnets. They also prepare the way of the 5-cm-aperture dipole magnet program to be started soon. In this paper, we analyze the mechanical behavior of the BNL prototypes during cool-down and excitation, and we attempt to relate this behavior to the magnet features. The data reveal that the mechanical behavior is sensitive to the vertical collar-yoke interference, and that the magnets ...
Lithium ion batteries use an oxide as a positive electrode and a carbon material as a negative electrode. The performances of carbon electrodes have rapidly evolved during the last years thanks to the substitution of soft carbons of Conoco or MCMB-2510 type by graphites (F-399, MCMB-2528) and then by hard carbons. These high capacity carbons (700 mAh/g) have higher service life and volume capacity than graphites but their irreversible losses are greater (>20%). In this work, materials with similar electrochemical performances are prepared by mechanical crushing. Mechanical crushing allows to obtain a wide range of carbon materials with various morphologies, specific surfaces and levels of disorder. The formation of the passivation film is directly linked with the surface of materials. A reaction scheme of the reversible and irreversible capacities has been defined and has permitted to obtain compounds with ...
A total of 50 000 tonnes of low-carbon steel sheet has been ordered for the LHC main magnets. After three years of production, about 10 000 tonnes of steel sheet have been produced by Cockerill-Sambre Groupe Usinor. This paper gives a summary of the manufacturing process and improvements implemented as well as an overview of the difficulties encountered during this production. Preliminary statistics obtained for the mechanical and magnetic steel properties are presented. (6 refs).
Two new identical insertion devices have been designed for the Daresbury SRS. They are 2T permanent-magnet multipole wigglers that will provide high flux in the X-ray region. This paper describes the magnetic and mechanical design of the arrays of steel pole pieces and permanent-magnet blocks. Also given is the engineering design of the support structure that will cope with the very large forces present while maintaining high levels of precision in gap setting and parallelism. The engineering design has been fully assessed using finite-element techniques to predict the deflections of critical parts of the structure. These two devices are due to be installed into the SRS by the end of 1998.
This paper is devoted to investigate the influences of thermal dispersion and magnetic field on a hot semi-infinite vertical porous plate embedded in a saturated Darcy-Forchheimer-Brinkman porous medium. The coefficient of thermal diffusivity has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The effects of transverse magnetic field parameter (Hartmann number Ha), Reynolds number Re (different velocities), Prandtl number Pr (different types of fluids) and dispersion parameter on the wall shear stress and the heat transfer rate are discussed.
From the gross conservation laws of thermodynamics in a convecting material we derive a bound on the ratio of the rate of production of mechanical or magnetic energy to the rate of internal radioactive...Full Text Available
Nanocrystalline materials can exhibit properties which are considerably different from their coarse-grained counterparts, making them unique for basic or applied research and also very promising for potential applications. The topics which are addressed in the present paper are magnetic properties and magnetic correlations on the nanometer scale, mechanical properties, in particular the influence of grain boundaries on the elastic and plastic behaviour, and vibration models of grain boundary atoms in nanostructured materials. (author)
Wavy interface morphology is observed in Magnetic Pulse Welding (MPW) similarly to that of the Explosion Welding process (EXW). It is recognized that interfacial waves are formed in a periodic manner and have well defined wavelength and amplitude. The phenomenon of wave formation in EXW has been subjected to extensive investigations in which empirical and numerical models have been published. In the present study, a wave formation mechanism for MPW is presented. This wave-creation mechanism was studied by evaluating the influence of sample geometry on wave morphology using stereoscopic optical microscopy. It was found that interfacial waves are formed in a Kelvin-Helmholtz instability mechanism. Reflected shock waves interact with the welding collision point at the weld interface, where in...
This paper deal with the research and develop (R and D) on Control Rod Magnetic Suspension Drive Mechanism (MSDM) of CARR. The MSDM is made up of tube, coil, armature, step motor, lead screw etc. The MSDM use electromagnetics as its main principle. The open solenoid electromagnet technique is employed to implement suspension function. It has advantages of high drive precision, high safety feature, good running reliability, easy maintenance and good economical property. The R and D process of MSDM has three phases including single coil electromagnet, principle prototype and engineering prototype. (author)
The paper outlines the underlying physical mechanisms by which electric and magnetic fields exist, with particular reference to high voltage transmission lines. Epidemiological and laboratory studies are the two approaches used in research into the subject and the shortcomings and inconstancies in the results are mentioned. Recent epidemiological results are presented together with possible mechanisms between fields and the human body. Attention is drawn to the work of certain international and national bodies concerning the alleged association between electromagnetic fields and ill-health, and their conclusions are reported. Finally, the policy of the Electricity Supply Board in Ireland is outlined. 2 figs.
LCTs (liquid crystal thermosets) have significant potential as a new class of structural materials. Through appropriate processing techniques using magnetic fields, the authors can orient the liquid-crystalline molecules and significantly improve the mechanical properties of the material. Most notably, the use of magnetic field processing can increase the tensile modulus threefold over the modulus in the unoriented material. This modulus value is only obtained in conventional epoxies in highly filled systems. Further investigation of the full set of mechanical properties of oriented LCTs will validate their approach to processing these materials. In the long run, the development of an economical and viable route to oriented LCTs will provide opportunities to expand the use of lightweight polymers in structural applications.
A theoretical analysis of formation and symmetry transformations is presented for Wigner molecules with N = 2,..., 20 electrons confined in quantum dots at high magnetic fields. Using the unrestricted Hartree-Fock method with the multicentre Gaussian basis, we have found that Wigner molecules with N {>=} 6 abruptly change their shape and symmetry with an associated jump in the first derivative of the ground-state energy, i.e. they undergo phase transitions. In particular, the phases of the Wigner molecules obtained just after emerging from the maximum-density droplet (MDD) phase possess a different symmetry from that formed at a high magnetic field. We show that the properties of the electron-electron interaction energy demonstrate very well both the breakdown of the MDD and the quasi-classical character of the Wigner molecule in the high magnetic field. Possible mechanisms of the MDD decay are ...
By ab-initio calculation we show that the (Ga,Fe)N ground state may be changed from anti-ferromagnetic to ferromagnetic by acceptor defect like Ga vacancies. The electronic structures are calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that we can increase the magnetic moment of Fe in p-type GaN by oxygen co-doping. Mechanism of exchange interactions between magnetic ions in p-type (Ga,Fe)N is also studied. The effect of external magnetic field on the electronic structure of (Ga, Fe)N and p-type (Ga, Fe)N is investigated.
A classical model is presented for magnetic field-induced Wigner crystallization in electron systems confined within two-dimensional quantum dots. In contrast to other classical models, this one does not treat an electron as a point charge; the electron density is assumed to take a Gaussian form corresponding to the lowest Landau level. Using a Monte Carlo method we have determined the equilibrium configurations as functions of the magnetic field. We have found a classical counterpart of the quantum maximum density droplet (MDD) and studied the breakdown of the MDD into a Wigner molecule as well as the transformations of the Wigner molecule shape induced by the external magnetic field. The phase diagram for the classical Wigner molecules has been presented and its qualitative agreement with previous quantum mechanical calculations has been shown.
A one-dimensional numerical model for the expansion of impact-produced vapor clouds is used to investigate magnetic field generation mechanisms in events such as meteor collisions with the moon. The resulting cloud properties, such as ionization fraction, electrical conductivity, radial expansion velocity, mass density, and energy density are estimated. The model is initiated with the peak shock states and pressure thresholds for incipient and complete vaporization of anorthosite lunar surface materials by iron and GA composition meteorites. The expansion of the spherical gas cloud into a vacuum was traced with a one-dimensional explicit lagrangian hydrodynamic code. The hypervelocity impact plasmas produced are found to be significant in the amplitudes and orientations of the magnetic fields generated. An ambient magnetic field could have been provided by the core dynamo, which would have interacted ...
Four 10 MW, highly-stabilized power supply modules have been installed at the National High Magnetic Field Laboratory in Tallahassee, FL, to energize water-cooled, resistive, high-field research magnets. The power supply modules achieve a long term current stability if 10 ppM over a 12 h period with a short term ripple and noise variation of <10 ppM over a time period of one cycle. The power supply modules can operate independently, feeding four separate magnets, or two, three or four modules can operate in parallel. Each power supply module consists of a 12.5 kV vacuum circuit breaker, two three-winding, step-down transformers, a 24-pulse rectifier with interphase reactors, and a passive and an active filter. Two different transformer tap settings allow rated dc supply output voltages of 400 and 500 V. The rated current of a supply module is 17 kA and each supply module has a one-hour overload capability of 20 kA. The ...
The relativistic motion of an electron is numerically analyzed in a tokamak having macroscopic magnetic turbulence. Stochasticity induced by the relativistic motion overwhelms the phase averaging effect, which provides a tokamak with an effective loss mechanism for the avoidance/suppression of runaway electron generation at a major disruption. On the other hand, electrons in the KAM (Kolmogorov-Arnold-Moser) region will be observed as a runaway snake. (author)
It has been shown that mechanical milling of iron in water results in formation of nanocrystalline magnetite Fe3O4 with an average particle size of 0.6 ?m, saturation magnetization of 77 Am2/kg and coercivity of ?150 A/cm. Along with magnetite, an antiferromagnetic Fe-O phase (?10 wt%), which is an aggregate of small iron-oxygen clusters forms.
By applying the mass, momentum, and angular momentum conservation laws and the maximum flow rate principle to swirling, effectively inviscid, incompressible flows in a circular tube with a sudden expansion and the direct-flow and reversed-flow Borda mouthpieces the dependence of the flow rate coefficient and mechanical energy losses on the radius ratio and nondimensional circulation is obtained. Several calculating approaches with potential and helical motion are introduced and investigated. In the case of helical motion, as the swirl decreases the axial core of the flow is found to close with a sudden change of the flow parameters.
This paper describes an exact solution to the problem of absorbing nitrogen dioxide into aqueous solution, in which case the nitrogen dioxide concentration is allowed to vary over a wide range. The authors have worked on the rate of calcium sulfate dihydrate scale formation on the reverse osmosis membrane and find this phenomena can be treated by the crystallization theory. The authors performed long-term experiments using calcium sulfate dihydrate solution with addition of sodium hexametaphosphate (SHMP) and commercially available organophosphates and investigated the mechanism of the inhibitor's action quantitatively.
The cathodic electrode process of Y(3+) ions on the Mo electrode in the LICl-KCl molten salt with YCl3(3wt%) in the temperature range of 450 - 530 deg. C has been investigated using cyclic voltammetry and chronopotentiometry. The convolution technique has been applied to the treatment of cyclic voltammogram. The results show that the reduction mechanism of Y(3+) ion is Y(3+) + 3e = Y, a simple one-step process. The cathodic process is very close to a reversible process under lower scanning rates, and is diffusion-controlled. The cathodic product is an insoluble product.
The most propagated mechanisms of stimulated radiation of electron beam such as Cherenkov one-particle and collective effects, ondulator and magnetic bremsshrahlung radiations, Doppler anomalous effect, Thompson and Raman scattering and radiation are discussed. Relation of spontaneous radiation mechanisms of individual electron and stimulated radiation effects in electron beams has been elucidated, grounds of linear electrodynamics of radiative beam instabilities are stated, and main mechanisms of their nonlinear stabilization are elucidated as well. Various simulated processes in electron beams are considered from the unique point of view using a simple mathematical apparatus and such physical laws as conservation and Newton laws.
The possibility of controlling the radial electric field of toroidal plasmas by injecting high energy electrons along the reversible loss cone orbit of the helical magnetic traps is investigated. It is well known that the radial electric field plays an important role in the confinement improvement scenario especially in the low collisional regime under the physics picture of neoclassical theory. For this purpose, it is made clear that the most suitable particles are transit particles, which show a transition from helically trapped orbits to blocked ones. It is also found that a parallel AC electric field launched from outside assists this transition and makes it possible for particles to penetrate deeply into the plasma. In addition we clarify that the viscosity of the plasma coupled with the helical field configuration provide a bifurcation of plasma states and its stable solution results in confinement improvement. (author)
...AquaMagna Water Conditioner and Descaler OCETA Environmental Technology & Business Profiles AQUAMAGNA WATER CONDITIONER AND DESCALER CAT. #03-018 CONTACT: Magna-Tek ...removal high-strength ceramic magnet no energy input The AquaMagna Water Conditioner and Descaler is a non-chemical method of water treatment. The technology uses ... Figure 1: The AquaMagna Water Conditioner and Descaler PROCESS/ PRODUCT APPLICATION: hard water domestic water process water reverse osmosis heat exchangers cooling ... For once-through or recirculating heating or cooling equipment, the AquaMagna descaler improves thermal efficiencies and reduces downtime. Figure 2 illustrates a cross-section ...
The potential use of uranium in the field of catalysis is presented in the first part of this paper. Numerous applications of uranium binary oxides, as well as mixed oxides, are reviewed with a special emphasis on the role of U-Sb-O catalysts in selective oxidation (and ammoxidation) processes. Attempts are made to correlate the electronic structure of uranium, and especially the role that 5f electrons play in bonding, with its promising catalytic properties. In the second part, new data are given for uranium-bismuth mixed oxides in the catalytic oxidation of CO by O_2. Kinetic tests performed in a flow microreactor allow a mechanism to be proposed that involves the direct participation of lattice oxygen of the catalyst in the chemical process (redox mechanism). The high activity can be related to the ability of uranium to change reversibly its oxidation state. (author).
Thermohydrogen treatment effect on microstructure and mechanical properties is studied for a cast heat resistant pseudo-#alpha#-titanium alloy Ti-6242 (Ti-6Al-2Sn-4Zn-2Mo) widely used as a heat resistant material with operating temperature up to 500 deg C. It is shown that reversible hydrogen alloying is a promising alternative to thermomechanical treatment for transformation of (#alpha#+#beta#)-titanium alloy structure. The application of thermohydrogen treatment is noted to be of particular efficiency for shaped casting technology as it allows a noticeable increase of mechanical properties at a lower cost. The alloy after thermohydrogen treatment and subsequent heat treatment in the (#alpha#+#beta#) - range possesses high values of yield strength fatigue properties, creep resistance and has a satisfactory ductility. A consideration is also given to thermohydrogen treatment effect on fatigue crack propagation and impact ...
The potential use of uranium in the field of catalysis is presented in the first part of this paper. Numerous applications of uranium binary oxides, as well as mixed oxides, are reviewed with a special emphasis on the role of U-Sb-O catalysts in selective oxidation (and ammoxidation) processes. Attempts are made to correlate the electronic structure of uranium, and especially the role that 5f electrons play in bonding, with its promising catalytic properties. In the second part, new data are given for uranium-bismuth mixed oxides in the catalytic oxidation of CO by O/sub 2/. Kinetic tests performed in a flow microreactor allow a mechanism to be proposed that involves the direct participation of lattice oxygen of the catalyst in the chemical process (redox mechanism). The high activity can be related to the ability of uranium to change reversibly its oxidation state.
Roux-en-Y gastric bypass surgery (RYGB) remains to be the most effective long-term treatment for obesity and its associated comorbidities, but the specific mechanisms involved remain elusive. Because RYGB patients appear to no longer be preoccupied with thoughts about food and are satisfied with much smaller meals and calorically dilute foods, brain reward mechanisms could be involved. Just as obesity can produce maladaptive alterations in reward functions, reversal of obesity by RYGB could normalize these changes or even further reset the food reward system through changes in gut hormone secretion, aversive conditioning and/or secondary effects of weight loss. Future studies with longitudinal assessments of reward behaviors and their underlying neural circuits before and after surgery wil...
Results of self-consistent local-spin-density-functional calculations are reported for the first time for the Ni(110) surface, represented by one-, three-, and five-layer slabs. Calculations for one- and five-layer slabs of Ni(100) are also reported. The behavior of the surface magnetization with varying slab thickness elucidates the nature and origin of the surface magnetic moment. We predict a 13% enhancement of the Ni(110) surface magnetic moment compared to the bulk value. For the Ni(100) surface, we find a smaller surface enhancement about 7%, compared to bulk, which agrees with the results of Jepsen et al. The enhancement of surface magnetic moments on Ni(100) and Ni(110) surfaces is attributed to s-d dehybridization at the surface and to the presence of electrostatic shifts required to maintain layer-by-layer charge neutrality. We find that the total d-electron charge is the same in each layer, ...
Magnetite nanoparticles with high self-heating capacity and low toxicity characteristics are a promising candidate for cancer hyperthermia treatment. In order to achieve minimum dosage to a patient, magnetic nanoparticles with high heating capacity are needed. In addition, the influence of physiological factors on the heat capacity of a material should be investigated in order to determine the feasibility. In this study, magnetite nanoparticles coated with lauric acid were prepared by co-precipitation of Fe{sup 3+}:Fe{sup 2+} in a ratio of 2:1, 5:3, 3:2, and 4:3, and the pH was controlled using NaOH. Structural and magnetization characterization by means of X-ray diffractometry (XRD) and a superconducting quantum interference device (SQUID) revealed that the main species was Fe{sub 3}O{sub 4} and further showed that most of the nanoparticles exhibited superparamagnetic properties. All of the magnetic nanoparticles showed a ...
Electron trapping in crossed electric and magnetic fields is an important mechanism by which electrical discharges can develop in low pressure gases. The authors report observations of discharges produced by this mechanism around a spherical anode in two space simulation chambers, namely the Space Plasma Interaction Experiment (SPIE) at the University of Maryland, and the NASA-Lewis B-2 chamber. They have identified two types of discharges in these experiments. In the B-2 chamber, the breakdown takes the form of a runaway dischage with spherical topology, limited only by the ability of the power supply to provide the current. In the SPIE chamber this type of discharge also occurs, in addition to a low current toroidal discharge which is observed at higher magnetic fields. They present measurements of both types of discharge and show how the trapping effect of the magnetic field ...
The purpose of this investigation is to show that resource to anisotropic compression along a magnetic field is not a necessary condition for star formation within large collapsing interstellar gas clouds. Although such a scenario would certainly eliminate the magnetic field and angular momentum problems associated with isotropically collapsing clouds, it is believed there is sufficient observational theoretical evidence to warrant the present study of magnetically braked, isotropically collapsing gas clouds. It is not attempted to disprove the hypothesis of anisotropic compression, but to offer instead, a reasonable alternative. Angular momentum transfer from magnetically braked, cool interstellar gas clouds of 10"2, 10"3 and 10"4 times the mass of the sun is examined. Magnetic torques acting on a contracting, rotating cloud, permeated by a frozen-in magnetic ...
We study diffusion of Cosmic Rays (CRs) in turbulent magnetic fields using test particle simulations. Electromagnetic fields are produced in direct numerical MHD simulations of turbulence and used as an input for particle tracing, particle feedback on turbulence being ignored. Statistical transport coefficients from the test particle runs are compared with earlier analytical predictions. We find qualitative correspondence between them in various aspects of CR diffusion. In the incompressible case, that we consider in this paper, the dominant scattering mechanism occurs to be the non-resonant mirror interactions with the slow-mode perturbations. Perpendicular transport roughly agrees with being produced by magnetic field wandering.
Experimentally it is shown that a movable grounded metallic plate placed inside a multi-dipole magnetic cage can vary the diffused plasma parameters such as density, plasma potential and electron temperature. Plasma is solely produced in the source section of a double plasma device by a dc hot filament discharge and a low-density plasma is produced in the target section by local ionization of neutral gas by the high energetic electrons coming from the source section. A grounded movable stainless steel plate is inserted in the target section of the device. The floating potential of the plate also changes depending on the position of the plate inside the magnetic cage.
Results of an investigation of the weldability of compact hollow automobile parts are reported. The use of magnetically impelled arc butt (MIAB) welding for a piston rod (OD_22_mm x 2.2_mm thickness), a shock-absorber (OD 40 mm x 2.2 mm) and a torque rod (OD 34 mm x 6 mm) has been investigated. Metallographic examination and comprehensive mechanical testing has been conducted to demonstrate the effectiveness of the method for joining of these types of automobile components
The long and resource intensive process of drug discovery and development is confronted with the basic challenge of providing effective and safe therapies at reasonably low costs. The better the mechanism of a disease is known, the higher the probability to find an appropriate therapy. Also, the better and earlier a disease can be diagnosed and characterized, the higher the chance to be able to interfere in this process with a chemical entity. This reasoning sets the framework for the use of imaging in drug discovery. We discuss the relevance of magnetic resonance imaging and spectroscopy to derive anatomical, functional, metabolic and target-related information in the context of pharmacological research in vivo. (author)
The kinetic and guiding center fluid theories of high-..beta.. plasma containment in mirror machines have been developed in a number of self-consistent models. The geometrical effects of magnetic field and ambipolar potential variation have been incorporated in a bounce-averaged Fokker-Planck code which shows that the square-well model somewhat overestimates the n tau and ..beta.. achievable in a mirror field. Simple analytic approximations to the resulting pressure profiles have been incorporated in three-dimensional fluid-equilibrium codes which show the effect of coil geometry on the maximum ..beta... Strongly curved vacuum fields allow higher ..beta.., but short plasmas in weakly curved fields tend to reverse the curvature locally before the mirror-mode limit is reached. Adiabaticity of particle orbits is described in terms of general formulas, applicable in high-..beta.. plasma equilibria, and is shown to break down close to the ...
A dipole magnet based on the common coil design, using prereacted Nb{sub 3}Sn superconductor, is under development at Fermilab, for a future Very Large Hadron Collider. This magnet has some innovative design and technological features such as single layer coils, a 22 mm wide 60-strand Rutherford type cable and stainless steel collars reinforced by horizontal bridges inserted between coil blocks. Both left and right coils are wound simultaneously into the collar structure and then impregnated with epoxy. In order to optimize the design and fabrication techniques an R&D program is underway. The production of cables with the required characteristics was shown possible. Collar laminations were produced, assembled and tested in order to check the effectiveness of the bridges and the validity of the mechanical design. A mechanical model consisting of a 165 mm long section of the ...
We study the spin dependence of accretion onto rotating Kerr black holes using analytic techniques. In its linear regime, angular momentum transport in MHD turbulent accretion flow involves the generation of radial magnetic field connecting plasma in a differentially rotating flow. We take a first principles approach, highlighting the constraint that limits the generation and amplification of radial magnetic fields, stemming from the transfer of energy from mechanical to magnetic form. Because the energy transferred in magnetic form is ultimately constrained by gravitational potential energy or Killing energy, the spin dependence of the latter allows us to derive spin-dependent constraints on the success of the accreting plasma to expel its angular momentum. We find an inverse relationship between this ability and black hole spin. If this radial magnetic field ...
Research performed at the Lawrence Livermore National Laboratory on the equilibrium and stability of a new class of ambient-temperature passive bearing systems is described. The basic concepts involved are: (1) Stability of the rotating system is only achieved in the rotating state. That is, disengaging mechanical systems are used to insure stable levitation at rest (when Earnshaw`s theorem applies). (2) Stable levitation by passive magnetic elements can be achieved if the vector sum of the force derivatives of the several elements of the system is net negative (i.e. restoring) for axial, transverse, and tilt-type perturbations from equilibrium. To satisfy the requirements of (2) using only permanent magnet elements we have employed periodic ``Halbach arrays.`` These interact with passive inductive loaded circuits and act as stabilizers, with the primary forces arising from axially symmetric ...
The Magnet Test Facility at Fermilab tests a variety of full-scale and model superconducting magnets for both R and D and production. As the design characteristics and test requirements of these magnets vary widely, the magnet test stand must accommodate a wide range of Data Acquisition (DAQ) and Control requirements. Such a system must provide several functions, which includes: quench detection, quench protection, power supply control, quench characterization, and slow DAQ of temperature, mechanical strain gauge, liquid helium level, etc. The system must also provide cryogenic valve control, process instrumentation monitoring, and process interlock logic associated with the test stand. A DAQ and Control system architecture that provides the functionality described above has been designed, fabricated, and put into operation. This system utilizes a modular approach that provides both ...
Stimulated bremsstrahlung in an undulating electric field in the lasing beam direction (electric wiggler) was shown to be possible from the quantum- mechanical viewpoint. Herein, this possibility is scrutinized from the viewpoint of classical electrodynamics. It is found that if stimulated bremsstrahlung in a transverse undulating magnetic field (magnetic wiggler) occurs, stimulated bremsstrahlung in the electric wiggler must also occur. We further show that a free electron laser (FEL) using a magnetic wiggler to provide a catalyzer field for stimulated bremsstrahlung cannot serve as a practical FEL operating in the soft x-ray region from both theoretical and experimental viewpoints. On the other hand, the authors demonstrate that the FEL using a traveling wake field in a two-beam elliptical pill-box cavity is well suited as a source of coherent radiation in the soft x-ray region.
The Large Hadron Collider (LHC), under construction at CERN, uses superconducting magnets operating at a temperature of 1.9 K to guide the circulating particles. A specific feature of the main magnets (dipoles and quadrupoles) is the two-in-one design with two magnetic channels in one common retaining structure. Indeed, the accelerator is made of two rings, mechanically linked, that have to be simultaneously aligned during the installation in the already existing LEP tunnel. The assembly tolerances of the LHC main magnets have been reconsidered to take into account the tight constraints on geometry. The dipoles are bent to follow closely the curvature of the circulating particles and to make a larger mechanical aperture available for the circulating particles. In order to minimise the geometrical errors the dipole assembly procedure is assisted by high precision ...
Downregulation of anterior pituitary GnRH-receptors by application of a slow release GnRH-implant offers an effective and reversible alternative to surgical castration of the male dog. Aim of the present study was to test the efficacy and the underlying mechanisms of a new non-biodegradable controlled-release device implant (Gonazon, Intervet, containing 18.5mg of the GnRH-agonist Azagly-Nafarelin). Eight male beagle dogs were implanted s.c. at the para-umbilical region. In four dogs implant removal was after 180 days (group 1), in the other four dogs after 365 days (group 2). Eleven weeks after implantation availability of LH was reduced (p<0.0001) by 70%. After an initial increase lasting for about 4 days, testosterone (T) and estradiol (E2) concentrations decreased (p<0.0001) to basal l...
As with mammalian enzymes, green crab (Scylla serrata) alkaline phosphatase can be activated by Mg2+ through a time-dependent course. The activation is mainly a Vmax effect. Tsou's method was used to study the kinetic course of activation. The results show that the enzyme was activated by a complexing scheme that had not been previously identified: the enzyme first reversibly and quickly binds Mg2+ and then undergoes a slow reversible course to activation, with a relatively high activation energy (78 +/- 4 kJ/mol) and a slow conformational change. The activation reaction is a single molecule reaction, and the apparent activation rate constant is independent of Mg2+ concentration if the concentration is sufficiently high. The microscopic rate constants of activation and the association constant were determined from the measurements. The proposed scheme may also be applied to the Mg2+ activation mechanism for mammalian ...
As lithium battery technology sets out to bridge the gap between portable electronics and the electrical automotive industry, cathode materials still stand as the bottleneck regarding performances. In the realm of highly attractive polyanion-type structures as high-voltage cathode materials, the sulfate group (SO{sub 4}){sup 2-} possesses an acknowledged superiority over other contenders in terms of open circuit voltage arising from the inductive effect of strong covalent S-O bonds. In parallel, novel lithium insertion mechanisms are providing alternatives to traditional intercalation, enabling reversible multi-electron processes securing high capacities. Combining both of these advantageous features, we report here the successful electrochemical reactivity of copper sulfate pentahydrate (CuSO{sub 4}.5H{sub 2}O) with respect to lithium insertion via a two-electron displacement reaction entailing the extrusion of metallic copper at a dual ...
A magnetic rhombohedral PrCo_2C_x (x = 0.05 #approx#0.25) phase (space group Rbar 3m), which is heavily twinned along the #left brace#110#right brace# and #left brace#211#right brace# planes, was identified. The twinning mechanism was explored by analyzing the reduction of crystal symmetry due to the cubic-rhombohedral phase transformation. The origin of the twinning and the formation of four twin variants were attributed to the insertion of carbon interstitials into Co_4 tetrahedrons along the bar 3 axis in the rhombohedral lattice, which corresponds to one of the four equivalent axes of its parent PrCo_2 cubic-lattice.
Concerns are sometimes expressed about an alleged link between exposure to the extremely low frequency electromagnetic fields occurring in proximity to electricity networks or equipment. Transmission lines are specifically mentioned. The underlying physical mechanisms are described by which electric and magnetic fields exist, with particular reference to high voltage transmission lines. Epidemiological and laboratory studies are the two approaches used in research into the subject and the shortcomings inherent in many such studies and the inconsistencies in the results are mentioned. Some of the more recent epidemiological studies are referred to, also the possible interaction mechanisms between fields and the human body. The work of certain international and national bodies which were established to review the results of research into the alleged association between electromagnetic fields and ill-health are reported. ...
Radiation-induced enteritis is a well-recognized sequel of therapeutic irradiation. Therefore we examined the radioprotective properties of Punica granatum peel extract (PPE) on the oxidative damage in the ileum. Rats were exposed to a single whole-body X-ray irradiation of 800 cGy. Irradiated rats were pretreated orally with saline or PPE (50 mg/kg/day) for 10 days before irradiation and the following 10 days, while control rats received saline or PPE but no irradiation. Then plasma and ileum samples were obtained. Irradiation caused a decrease in glutathione and total antioxidant capacity, which was accompanied by increases in malondialdehyde levels, myeloperoxidase activity, collagen content of the tissue with a concomitant increase 8-hydroxy-2'-deoxyguanosine (an index of oxidative DNA damage). Similarly, pro-inflammatory cytokines (TNF-?, IL-1? and IL-6) and lactate dehydrogenase were elevated in irradiated groups as compared to control. PPE treatment reversed ...
The effect of Mo addition on the glass-forming ability (GFA), magnetic properties, mechanical properties and corrosion resistance of (Fe0.76Si0.096B0.084P0.06)100-xMox (x=0, 2, 4 and 6at.%) bulk glassy alloys (BGAs) with high Fe contents was investigated. The 2at.% Mo addition makes the alloy composition approach towards a eutectic point, which could result in an increase in the GFA. The BGA rod with diameters up to 3.5mm was produced by copper mold casting. These BGAs exhibit a rather high saturation magnetization of 0.98-1.51T and lower coercive force of 1.7-2.1A/m. A significant improvement in corrosion resistance was observed with microalloying Mo element in 1N H2SO4 solution. Furthermore, these Fe-based BGAs show super-high strength of ~3.3GPa and Young's modulus of 200GPa.
Surface deposition probe techniques have been shown to be an effective means of determining the characteristics of the plasma edge region of magnetic confinement devices. Experimental results on ISX-B and EBT-S have led to a consistent picture of the edge plasma and the dominant impurity introduction mechanisms. This picture is supported by numerous other measurements and emphasizes the importance of concentrating several techniques on the complex problems of plasma fusion.
Lifetimes have been measured for a dipole band in {sup 139}Sm using DSAM. The deduced B(M1) and B(E2) values as well as B(M1)/B(E2) ratios are compared with calculations in the framework of the TAC (Tilted Axis Cranking) and SPAC (Shears mechanism with Principal Axis Cranking) models. The dipole band in {sup 139}Sm can be considered as a magnetic rotational band with a prolate or triaxial nuclear deformation. (orig.)
Lifetimes have been measured for dipole bands in {sup 142}Gd using DSAM. The deduced B(M1) and B(E2) values as well as B(M1)/B(E2) ratios are compared with calculations in the framework of the TAC (Tilted Axis Cranking) and SPAC (shears mechanism with Principal Axis Cranking) models. The dipole bands DB1 to DB4 can be interpreted as magnetic rotational bands. (orig.)
The oxidation of n-butylbenzene was studied in a jet-stirred reactor (JSR) at 10atm in dilute conditions providing new experimental results over the low- and high-temperature range 550-1180K, and variable equivalence ratio (0.25ϕ1.5). They consisted of concentration profiles of the reactants, stable intermediates and final products, measured as a function of temperature, at a constant residence time of 1s, by sonic probe sampling followed by on-line GC-MS and off-line GC-TCD-FID and GC-MS analyses. The oxidation of n-butylbenzene in these conditions was modeled using a detailed chemical kinetic reaction mechanism (404 species and 2210 reactions, most of them reversible) deriving from a previous scheme proposed for the ignition, oxidation, and combustion of simple aromatics (benzene,...
A quantum mechanical analysis of the guided light in integrated photonics waveguides is presented. The analysis is made starting from one-dimensional (1D) guided vector modes by taking into account the modal orthonormalization property on a cross section of an optical waveguide, the vector structure of the guided optical modes and the reversal-time symmetry in order to quantize the 1D vector modes and to derive the quantum momentum operator and the Heisenberg equations. The results provide a quantum-consistent formulation of the linear and nonlinear quantum light propagations as a function of forward and backward creation and annihilation operators in integrated photonics. As an illustration, an application to an integrated nonlinear directional coupler is given, that is, both the nonlinear momentum and the Heisenberg equations of the nonlinear coupler are derived.
Aim:To examine the electrophysiological effects of sophocarpine on action potentials (AP) and ionic currents of cardiac myocytes and to compare some of these effects with those of amiodarone.Methods:Langendorff perfusion set-up was used in isolated guinea pig heart, and responses to sophocarpine were monitored using electrocardiograph. Conventional microelectrode, voltage clamp technique and perforated patch were employed to record fast response AP (fAP), slow response AP (sAP) and ionic currents in guinea pig papillary muscle or rabbit sinus node cells.Results:Tachyarrhythmia produced by isoprenaline (15 ?mol/L) could be reversed by sophocarpine (300 ?mol/L). Sophocarpine (10 ?mol/L) decreased the amplitude by 4.0%, maximal depolarization velocity (Vmax) of the fAP by 24.4%...
The electrochemical behavior of Sb(III) ions was investigated in LiCl-KCl molten salt at 673K. The reaction mechanism and transport parameters of electroactive species were determined by transient electrochemical techniques (such as cyclic voltammetry, square wave voltammetry, chronopotentiometry and chronoamperometry) at a molybdenum electrode. The results showed that electrochemical reduction of Sb(III) in LiCl-KCl melts occurred in a reaction step with an exchange of three electrons. A voltammogram with a different scan rate in LiCl-KCl containing 1.45x10^-^4molcm^-^3 SbCl3 showed that the deposition/dissolution reaction of Sb(III) ions was not completely reversible. The diffusion coefficient of Sb(III) ions was 1.65(+/-0.01)x10^-^5cm^-^2s^-^1 at 673K. The electroreduction of Sb(III) io...
FeSi{sub 6}/graphite composite was prepared by mechanical ball milling. The FeSi{sub 6} alloy particles consist of an electrochemically active silicon phase and inactive phases FeSi{sub 2}, distributed uniformly in the graphite matrix. The composite anode offers a large reversible capacity (about 800 mAh g{sup -1}) and good cycleability, due to the buffering effect of the inactive FeSi{sub 2} phase and graphite layers on the volumetric changes of Si phase during lithium-Si alloying reaction. Since FeSi{sub 6} alloy is a low-cost industrial material, this alloy compound provides a possible alternative for development of high capacity lithium-ion batteries. (author)
As lithium battery technology sets out to bridge the gap between portable electronics and the electrical automotive industry, cathode materials still stand as the bottleneck regarding performances. In the realm of highly attractive polyanion-type structures as high-voltage cathode materials, the sulfate group (SO4)^2^- possesses an acknowledged superiority over other contenders in terms of open circuit voltage arising from the inductive effect of strong covalent S-O bonds. In parallel, novel lithium insertion mechanisms are providing alternatives to traditional intercalation, enabling reversible multi-electron processes securing high capacities. Combining both of these advantageous features, we report here the successful electrochemical reactivity of copper sulfate pentahydrate (CuSO4.5H2O...
We explore a novel phenomenon of focused ion beam (FIB) induced bending of carbon nanopillars or cantilever structures. The bending occurs towards the ion beam during scanning. The explanation of this bending has been sought on the basis of a model which considers temperature rise and gradients caused by the impinging ion beam. The process is controllable and reversible, which makes it highly suitable for in situ manipulation to make desired 3D shapes by the piecewise bending of the nanopillars and cantilever structures during their fabrication using electron beam or FIB chemical vapor deposition (EB-CVD or FIB-CVD). Its usefulness in the fabrication of nanosize mechanical components has been demonstrated by making a branch structure from a single cantilever.
To apply the CO{sub 2} absorber at about 1000{sup o}C for integrated coal gasification combined cycle (IGCC) furnace, the reactions of calcium oxide and CO{sub 2} at high temperatures was examined. Calcium carbonate reacts with sodium hydrogen carbonate below 200{sup o}C and forms sodium-calcium complex carbonate. The sodium-calcium complex carbonate melts at 813{sup o}C, and the carbon dioxide absorption and discharge reversible reactions of calcium-oxide takes place via liquid at around 1000{sup o}C. Sintering of calcium oxide at high temperature has been successfully avoided by the addition of sodium.
The kinetics of biosorption and desorption of lindane by live activated sludge and the fungus R. arrhizus was studies. The results from the use of live activated sludge suggest that besides biosorption, other lindane removal mechanisms acted in parallel. Most probably, biodegradation. A relationship between biodegradation and bisorption-desorption was established. Mass spectroscopy and gas chromatography studies suggested the presence of lindane biodegradation by products. Lindane accumulated by the live activated sludge could be desorbed while being biodegraded at the same time. Values for lindane biokinetic constants were estimated. Biosorption of lindane by live R. arrhizus is a rapid and reversible process with no indication of biodegradation. Values for the lindane biotransformation kinetic coefficients were estimated. (orig.).
The bulk removal of CO/sub 2/ from industrial gases is a frequently applied process in the field of gas-treating. Usually chemical solvents are used in order to increase both the solvent-loading capacity and the absorption rate. These solvents often are aqueous solutions of alkanolamines. The loaded-liquid is regenerated at high temperatures with the aid steam. In the present study absorption rates are experimentally determined in various mixtures of amines over a wide range of concentrations. Simultaneously, a model was developed for the description of mass transfer accompanied by parallel reversible chemical reactions. The equations of this mass transfer model could not be solved analytically and therefore numerical techniques were used to obtain an exact description of this process. This model also includes the asymptotic situations of homogeneous catalysts and shuttle mechanism for which in the literature several approximate solutions have ...
Uridine phosphorylase (UPP) catalyzes the reversible conversion of uridine to uracil and ribose-1-phosphate and plays an important pharmacological role in activating fluoropyrimidine nucleoside chemotherapeutic agents such as 5-fluorouracil and capecitabine. Most vertebrate animals, including humans, possess two homologs of this enzyme (UPP1 & UPP2), of which UPP1 has been more thoroughly studied and is better characterized. Here, we report two crystallographic structures of human UPP2 (hUPP2) in distinctly active and inactive conformations. These structures reveal that a conditional intramolecular disulfide bridge can form within the protein that dislocates a critical phosphate-coordinating arginine residue (R100) away from the active site, disabling the enzyme. In vitro activity measurem...
Glioblastoma multiforme is the most aggressive form of human brain tumor, which has no effective cure. Previously, we have demonstrated that overexpression of the C-terminal fragment of the human telomerase reverse transcriptase (hTERTC27) inhibits the growth and tumorigenicity of human cervical cancer HeLa cells. In this study, the therapeutic effect and molecular mechanisms of hTERTC27-mediated cancer gene therapy were further explored in vivo in established human glioblastoma xenografts in nude mice. We showed that intratumoral injection of adeno-associated virus carrying hTERTC27 (rAAV-hTERTC27) is highly effective in reducing the growth of the subcutaneously transplanted glioblastoma tumors. Histological analyses showed that rAAV-hTERTC27 treatment leads to profound necrosis, apoptosi...
The present report addresses several aspects of the free electron laser (FEL) and accelerator, including their features, potentials, mechanisms, beams emitted from undulator, FEL produced by helical mangnetic field, major problems with FEL, etc. In FEL, relativistic electron beams interact with an electromagnetic field with periodically changing intensity to produce coherent electromagnetic waves with variable wavelength. The capability of varying its wavelength represents the greatest advantage over conventional lasers. Any periodic magnetic field can serve as a wiggler. A wiggler can be used both in an amplifier and oscillator. A periodic magnetic field used may be either of a parallel type or of a helical type. The polarization of emitted beams depends on the shape of the magnet regardless of whether its field is parallel or helical. An equation is derived in the report which expresses the wavelength ...
To evaluate whether children with and without autism could exhibit (a) functional equivalence in the course of yoked repeated-reversal training and (b) reversal learning set, 6 children, in...Full Text Available
BackgroundHIV-1 reverse transcriptase (RT) is a heterodimer composed of p66 and p51 subunits and is responsible for reverse transcription of the viral RNA genome into DNA. RT can...Full Text Available
Apart from conventional phase transitions driven by the thermal effects, quantum phase transitions generated by quantum fluctuations have their own mechanisms that are reflected in critical phenomena. Quantum phase transitions have an origin from spontaneous symmetry breaking commonly to thermal phase transitions. Even in this case, inherent quantum fluctuations substantially modify and yield new aspects. Quantum phase transitions have, however, another mechanism caused by topology changes, which gives completely new characters. Recently, a mechanism which connects these two has been found. Proimities from first-order transitions and phase separatins as well as from multiphase coexistence also generate characteristic and unconventional quantum criticalities. Understanding novel quantum criticalities offers a firm basis of recent active researches on fields such as magnetism, ferroelectricity and ...
The thermal properties (thermal conductivity, thermal diffusivity, thermoelectric power, thermal dilatation, etc.) and the mechanical properties (Young's modulus, strength, hardness, fracture toughness, etc.) have been measured at low temperatures (4-300K) and under a high magnetic field (0-10T) for about 50 REBaCuO bulks (RE=Y, Gd, Nd, Sm, Dy, etc.). We have constructed the database of these properties and opened it on the Web site (thermal properties: http://ikebehp.mat.iwate-u.ac.jp/database.html and mechanical properties: http://paris.mech.iwate-u.ac.jp/sc-bulk/database.html). The influence of the species of RE ions, the content, size and dispersion of the RE211 (or Nd422) phase and Ag particles and the defects distribution on these properties is characterized.
''Magnetic braking'' of the plasma toroidal rotation in the high confinement H mode by applied resonant, low m,n=1 static error fields is used in DIII-D [Nucl. Fusion 31, 875 (1991)] as an independent control to evaluate the E_rxB stabilization of microturbulence in the plasma core. In the core (#rho# approx-lt 0.9) of a tokamak, the radial electric field and its shear are dominated by toroidal rotation. The fundamental quantity for shear stabilization of microturbulence is shear in the velocity of the fluctuations v_p_e_r_p_e_n_d_i_c_u_l_a_r#approx#E_rxB/B#centre dot#B which in the core is v_p_e_r_p_e_n_d_i_c_u_l_a_r#approx#v_#phi#B_#theta#/ B_#phi#. With magnetic braking greatly decreasing the toroidal rotation and thus reducing the core radial electric field and shear, far infrared (FIR) measurements of density microturbulence show downshifting in frequency near #rho##approx#0.8 as a result of the reduced Doppler shift ...
The authors have interpreted 1,400 km of industry and government multichannel seismic reflection data from eastern Lake Superior. Seismic sequences have been identified by using reflection character and reflector terminations and truncations. This framework, coupled with outcrop information, has allowed them to assign lithologic units to some of these reflectors and reconstruct the timing and geometry of structures within the basin. The authors have mapped the Base Jacobsville-Bayfield Group/Top oronto Group, Base oronto Group/Top Keweenawan volcanics, and Basement as well as several reflectors internal to these groups. Integration of gravity and magnetic data with the seismic grid permits regional mapping of faults and folds between seismic lines. In the eastern part of the basin, high-angle basement-involved reverse faults, such as the southeastern combination of the Keweenaw fault, trend NNW-SSE, while broad folds trend E-W. The Keweenaw ...
The coupling between cerebral metabolic rate of oxygen (CMRO2) and blood flow (CBF) in response to visual stimulation was evaluated by means of a model of oxygen delivery. The model predicted a nonlinear relationship between stimulus-evoked changes of oxygen consumption and blood flow. The magnitude of the CMRO2/CBF ratio index (IO2) was used to indicate the degree of flow-metabolism coupling prevailing in specific areas of the brain during physiological stimulation. Therefore, the index provided a measure of the blood oxygenation level dependent (BOLD) magnetic resonance contrast. To evaluate the changes of IO2 in response to visual stimulation, the model was applied to the effect of a changing flicker rate of a visual stimulus on the magnitudes of CBF, CMRO2, and oxygen diffusion capacity, in the human brain. Positron emission tomography (PET) was used to measure the CBF and the CMRO2 in 12 healthy volunteers who viewed a cross-hair (baseline) or a yellow-blue ...
Recent experiments with TFTR, D-III-D and JET involving the injection and trapping of low density beams of high energy large orbit ions indicate that large orbit non-adiabatic ions slow down and diffuse classically in the presence of anomalous fluctuations and transport of adiabatic majority particles. Accordingly, we consider conceptual fusion reactors(N. Rostoker, M.W. Binderbauer and H.J. Monkhorst, Science) 278, 1419 (1997). based on classical confinement of fuel ions and fusion products(M.W. Binderbauer and N. Rostoker, J. Plasma Phys.) 56, 451 (1996).. The magnetic confinement geometry of the proposed designs is a Field Reversed Configuration. A survey of experimental results on instabilities and their characteristics as related to these reactor concepts is presented. Particular focus will be given to long wavelength (as compared to gyro-radius) and low frequency (?<< c/r_o, r_o=3D major radius of annular current ring) instabilities ...
Aldosterone has been suggested to elicit vessel contraction via a nongenomic mechanism. We tested this proposal in microdissected, perfused rabbit renal afferent arterioles. Aldosterone had no effect on internal diameter in concentrations from 10(-10) to 10(-5) mol/L, but aldosterone abolished the ability of 100 mmol/L KCl to induce vascular contraction. The inhibitory effect of aldosterone was observed from 1 pmol/L. The inhibitory effect was significant after 5 minutes and maximal after 20 minutes and was fully reversible. Actinomycin D (10(-6) mol/L) prolonged the effect of aldosterone. The effect was abolished by the mineralocorticoid receptor antagonist spironolactone (10(-7) mol/L) but not by the glucocorticoid receptor antagonist mifepristone (10(-6) mol/L). The K+-mediated increase of intracellular calcium concentration in afferent arterioles was not affected by aldosterone. Mineralocorticoid receptor was detected by ...
Crystalline MnMoO{sub 4} was synthesized using a conventional solid reaction method and investigated for its physical and electrochemical properties as an anode material for Li secondary battery. The reversible amount of Li insertion/removal of MnMoO{sub 4} anode during the first cycle was about 800 mA h/g, accompanied by irreversible structural transformation into amorphous material. The amorphization during the first Li insertion was investigated by structural analysis using XRD of electrode. The charge compensation during Li insertion/removal was examined by measurement of X-ray Absorption Near Edge Structure (XANES) spectroscopy. Despite its irreversible structural transformation to amorphous during the first lithiation, subsequent cycles showed a reasonable cyclability. This paper presents the electrochemical properties of MnMoO{sub 4} and discusses the mechanism underlying the Li insertion/removal process.
The multidimensional countercurrent two-phase flow regimes that occur in a pressurized-water reactor (PWR) vessel downcomer during the refill phase of a large-break loss-of-coolant accident are studied using a transparent 1/10 scale model of a PWR vessel. The various flow regimes and their distribution in the downcomer have been identified and mapped for a range of air-water flooding experiments. The two-phase flow patterns that are identified in the downcomer included various types of film flows, droplet flows, countercurrent churn flows and cocurrent flows depending on the flooding condition. Through observation of the two-phase flow dynamics it was deduced that the physical mechanisms associated with the flooding processes could be separated into a liquid entrainment process and a film flow reversal process. In addition to the above exercise, the effect of non-uniform injection of water into the downcomer via different combinations of cold ...
The multidimensional countercurrent two-phase flow regimes that occur in a pressurized-water reactor (PWR) vessel downcomer during the refill phase of a large-break loss-of-coolant accident are studied using a transparent 1/10 scale model of a PWR vessel. The various flow regimes and their distribution in the downcomer have been identified and mapped for a range of air-water flooding experiments. The two-phase flow patterns that are identified in the downcomer included various types of film flows, droplet flows, countercurrent churn flows and cocurrent flows depending on the flooding condition. Through observation of the two-phase flow dynamics it was deduced that the physical mechanisms associated with the flooding processes could be separated into a liquid entrainment process and a film flow reversal process. In addition to the above exercise, the effect of non-uniform injection of water into the downcomer via different combinations of cold ...
The mechanism of trypsin inactivation by intact Hymenolepis diminuta has been investigated by biochemical and autoradiographic methods. Although worms inactivate trypsin and chymotrypsin in vitro, no inactivation of other endoproteases (subtilisin, pepsin and papain) could be demonstrated. Trypsin inactivation, as demonstrated by macromolecular substrates (azoalbumin, hemoglobin and casein), could not be detected using low molecular weight synthetic substrates such as N-p-benzoyl-DL-arginine-p-nitroanilide (BAPA) or N-p-tosyl-L-arginine methyl ester (TAME). In addition, the kinetic parameters (K/sub m/ and k_3) for H. diminuta-inactivated trypsin, using BAPA as the substrate, were not different from those of the native enzyme. The number of active sites for both native and inactivated trypsin were determined by titration with p-nitro-phenyl-p'-guanidinobenzoate. Absorbance values for both titrations were found to be identical. Dialysis, heating to 50 C, or repeated ...
The usual method of introducing engineers to the concept of dislocations and their role in plastic flow is to compare an estimate of the theoretical strength of solid (of order {micro}/30 where {micro} is the shear modulus) and the observed strength of either single crystals ({mu}/10{sup 4}) or practical engineering material such as structural steels where the yield stress in shear is of order {mu}/10{sup 3}. However, if one considers the problem in reverse, one can consider the accumulation of dislocations as an important mechanism by which one can produce engineering materials in which the strength level approaches the theoretical strength. If one assumes that the flow stress can be expressed in terms of te mean free path between stored dislocations or as the square root of the global dislocation density, then one can see the influence of dislocation density in a diagrammatic form. It is clear that the strengthening by dislocation ...
Abstract Young protostars embedded in circumstellar discs accrete from an angular momentum rich mass reservoir. Without some braking mechanism, all stars should be spinning at or near breakup velocity. In this paper, we perform simulations of the self-gravitational collapse of an isothermal cloud using the orion adaptive-mesh refinement code and investigate the role that gravitational torques might play in the spin-down of the dense central object. While magnetic effects likely dominate for low-mass stars, high-mass and Population III stars might be less well magnetized. We find that gravitational torques alone prevent the central object from spinning up to more than half of its breakup velocity, because higher rotation rates lead to bar-like deformations that enable efficient angular mome...
The interlayer exchange coupling between Co/Pt perpendicular-to-plane magnetized layers across a thin IrMn spacer layer was experimentally studied. In contrast to earlier studies on interlayer coupling through antiferromagnetic NiO, which revealed an oscillatory coupling behavior as a function of NiO thickness, a ferromagnetic coupling was observed here in the range of IrMn thickness between 0.6 and 1.5nm and antiferromagnetic between 1.5 and 2.5nm. The antiferromagnetic coupling is attributed to an orange peel magnetostatic mechanism whereas the ferromagnetic coupling is attributed to an out-of-plane polarization of the antiferromagnetic IrMn layer induced by the interfacial exchange interaction with the adjacent out-of-plane ferromagnetic layers. Measurements of hysteresis loops versus t...
The thermal stability and deformability of Mn-Al-C alloys containing 0.6 pct C are investigated experimentally as a function of excess phase content. It is shown that an increase in Mn content from 68.9 to 73.5 pct leads to increased stability of the high-temperature epsilon phase. The enrichment of the system Mn-Al-Cu in Mn and Al above the optimum composition leads to the formation of nonmagnetic excess phases, eta and beta, which reduce the magnetization of the alloy. In addition, a decrease in thermal stability is observed in the alloy with 73.5 pct Mn due to the decomposition of the ferromagnetic phase. 7 references.
The central engine of Gamma Ray Bursts is hidden from direct probing with photons mainly due to the high densities involved. Inferences on their properties are thus made from their cosmological setting, energetics, low-energy counterparts and variability. If GRBs are powered by hypercritical accretion onto compact objects, on small spatial scales the flow will exhibit fluctuations, which could in principle be reflected in the power output of the central engine and ultimately in the high energy prompt emission. Here we address this issue by characterizing the variability in neutrino cooled accretion flows through local shearing box simulations with magnetic fields, and then convolving them on a global scale with large scale dynamical simulations of accretion disks. The resulting signature is characteristic, and sensitive to the details of the cooling mechanism, providing in principle a discriminant for GRB central engine properties.
Diamagnetic samples placed in a strong magnetic field and a magnetic field gradient experience a magnetic force. Stable magnetic levitation occurs when the magnetic force exactly counter balances...Full Text Available
Nanocrystalline samples of Fe_8_0Mo_2_0 and Fe_5_0Mo_5_0 alloys were prepared by the mechanical milling method. The structure, lattice parameters, and crystallite size were determined by the X-ray diffraction. The magnetic properties of the milled products were determined by the Moessbauer spectroscopy. It was observed that in the case of the Fe_8_0Mo_2_0 alloy a solid solution of Mo in Fe was formed with the lattice parameters of the Fe increasing from 0.28659 nm to 0.29240 nm and the crystallite size decreasing from 250 nm to 20 nm. In the case of the Fe_5_0Mo_5_0 alloy there were no clear changes in values of the lattice parameters of Fe and Mo during the milling process, but the crystallite size decreased from 200 to 15 nm. Moessbauer spectra revealed different magnetic phases in the machanosynthesized Fe_Mo samples. In the case of the Fe_8_0Mo_2_0 alloy, the spectrum for the milled mixture indicated the formation of ...
Nanocrystalline Fe75Si20M5 (M = Al, B and Cr) powders were synthesized by mechanical alloying in a planetary ball mill from high purity elemental powders. Evolution of non-equilibrium solid solutions of ?-Fe[Si,(Al, B, Cr)] with a nanocrystalline structure was accompanied by the introduction of a large number of dislocation defects in the course of the milling process. Fe sites get substituted by Si and M (M = Al, B, Cr) atoms during the milling process. The structural change and the resulting disorder are reflected in the changes in the lattice parameter and average magnetic moment of the powders milled for various time periods. The effective magnetic anisotropy increases linearly with the milling time. An increase in coercivity with increasing milling time was observed which could be attributed to the introduction of dislocations and the reduction in the powder particle size during milling. The presence of dislocations ...
... Title : Refining the Magnetic Forming Capability. ... Abstract : The purpose of this project was to refine the in-house magnetic forming capability. ...
in pulse applications such as magnetic forming. ... In magnetic-forming electric circuitry, the ..... Aspects of Electrohydraulic land Magnetic Forming. ...
In order to verify long-term reliability of amorphous alloy wound core distribution transformers, accelerated aging tests and field trials used by actual transformers were practiced. As for accelerated aging tests, short-circuit tests were added to imitate mechanical stress in operation on a utility's distribution system. As a result, even after the equivalent of 30 years, which was the normal expected transformer's life, magnetic characteristic was unchanged, so these transformers could be operated. Also, about field trials, two hundred transformers of four kinds were installed on a utility's distribution system to look into no-load characteristics. They were equipped with a mechanism to measure load current, background vibration and lightning surge current, so the influence for magnetic characteristic could be inspected. As a result, remarkable change wasn't seen ...
High-resolution proton nuclear magnetic resonance spectroscopy has been used to investigate the molecular mechanism of the Bohr effect of human normal adult hemoglobin in the presence of two allosteric effectors, i.e., chloride and inorganic phosphate ions. The individual hydrogen ion equilibria of 22-26 histidyl residues of hemoglobin have been measured in anion-free 0.1 M HEPES buffer and in the presence of 0.18 M chloride or 0.1 M inorganic phosphate ions in both deoxy and carbonmonoxy forms. The results indicate that the #beta#2-histidyl residues are strong binding sites for chloride and inorganic phosphate ions in hemoglobin. The affinity of the #beta#2-histidyl residues for these anions is larger in the deoxy than in the carbonmonoxy form. Nevertheless, the contribution of these histidyl residues to the anion Bohr effect is small due to their low pK value in deoxyhemoglobin in anion-free solvents. The interactions of chloride and ...
During the operation of a tokamak, the first wall elements suffer very high heat fluxes. Heat is removed by internal cooling by means of water, helium or fluid metal. The resulting inhomogeneous temperature field cause internal stresses which, due to the pulsed operation are of cyclic nature. Additional mechanical stresses in the first wall may be caused by disruptions or vertical plasma movements. During theses events high currents are induced in the metallic part of the first wall which by their interaction with the magnetic field of the tokamak lead to mechanical forces. These electromechanical stresses may lie beyond the yield stress of the structural material. From the interaction of thermal and mechanical forces, a complex stress state is achieved which under certain circumstances may lead to premature failure and/or to progressive plastic deformations (ratcheting). In order to study the boundary ...
It is well known that one of the main advantages of the high speed forming (HSF) processes is the improvement in the forming limits of the used materials.Using the Electromagnetic Forming (EMF) technology two materials have been tested with different mechanical and physical properties: the AA5754 aluminium and the AZ31B magnesium alloys.The EMF process principle can be described as follows: A significant amount of electrical energy is stored in a bank of capacitors which are suddenly discharged releasing all the stored energy. This electric discharge runs through a coil which generates an intense transient magnetic field. At the same time transient Eddy currents are induced in the electrically conductive part placed some millimetres far from the coil. Another intense magnetic field is generated due to those Eddy currents but on the opposite direction as the one generated by the coil. A big magnetic ...
It is well known that one of the main advantages of the high speed forming (HSF) processes is the improvement in the forming limits of the used materials.Using the Electromagnetic Forming (EMF) technology two materials have been tested with different mechanical and physical properties: the AA5754 aluminium and the AZ31B magnesium alloys.The EMF process principle can be described as follows: A significant amount of electrical energy is stored in a bank of capacitors which are suddenly discharged releasing all the stored energy. This electric discharge runs through a coil which generates an intense transient magnetic field. At the same time transient Eddy currents are induced in the electrically conductive part placed some millimetres far from the coil. Another intense magnetic field is generated due to those Eddy currents but on the opposite direction as the one generated by the coil. A big magnetic ...
Multi-core MgB_2/Ti/Cu/SS composite wire has been made by the in situ approach. Mechanical properties, interdiffusion reactions and critical currents were studied after heat treatments at temperatures between 500 and 850 "0C. Cu diffusion into the Ti layer occurs for all samples, resulting in the formation of intermetallic compounds at the Cu/Ti interface. EDX analysis has revealed the temperature dependence of all interface reactions. In spite of element reactions the critical current densities 10"5 A cm"-"2 and 10"4 A cm"-"2 were measured in liquid helium at magnetic fields 5 T and 9.5 T, respectively. 10"4 A cm"-"2 at 20 K is measured in an external field of 4 T.
Colloidal nanocrystals attract significant interest due to their potential applications in electronic, magnetic, and optical devices. Nanocrystal supercrystals (NCSCs) are particularly appealing for their well ordered structure and homogeneity. The interactions between organic ligands that passivate the inorganic nanocrystal cores critically influence their self-organization into supercrystals, By investigating the mechanical properties of supercrystals, we can directly characterize the particle-particle interactions in a well-defined geometry, and gain insight into both the self-assembly process and the potential applications of nanocrystal supercrystals. Here we report nanoindentation studies of well ordered lead-sulfide (Pbs) nanocrystal supercrystals. Their modulus and hardness were found to be similar to soft polymers at 1.7 GPa and 70 MPa respectively and the fractures toughness was 39 KPa/m1/2, revealing the extremely brittle nature of ...
Four general topics are covered in respect to the natural space radiation environment: (1) particles trapped by the earth`s magnetic field, (2) cosmic rays, (3) radiation environment inside a spacecraft, (4) laboratory radiation sources. The interaction of radiation with materials is described by ionization effects and displacement effects. Total-dose effects on MOS devices is discussed with respect to: measurement techniques, electron-hole yield, hole transport, oxide traps, interface traps, border traps, device properties, case studies and special concerns for commercial devices. Other device types considered for total-dose effects are SOI devices and nitrided oxide devices. Lastly, single event phenomena are discussed with respect to charge collection mechanisms and hard errors. (GHH)
The thermonuclear reactivity of deuterium(D) - tritium(T) fusion plasma with spin-polarized fuel has been studied. Two mechanisms of depolarization, collisions and waves, in the high temperature fusion plasma have been considered. The binary collisions have been found not to change the nuclear spin states. The waves with a frequency of a few GHz, however, changes the spin states appreciably, when {delta}B/B{sub 0} (the ratio of the amplitude of the fluctuating magnetic field to the external field) becomes larger than 10{sup -5}. (author)
The mechanism of abrupt increase of the giant magneto impedance (GMI) ratio in the ion irradiated Co-based amorphous ribbon has been investigated. The grazing incident X-ray diffraction and transmission electron microscope were used to characterize the samples before and after ion irradiation. The GMI-ratio considerably increased in the ion irradiated samples and the GMI response showed strong dependence on the driving frequencies. The Barkhausen noise (BN) signals are increased for the Ar ion irradiated sample with dose of 1x10^1^7 ion/cm^2. The results are interpreted in terms of GMI variation associated with domain wall dynamics.
Polarized antiprotons produced by spin filtering with an internal polarized gas target provide access to a wealth of single- and double-spin observables, thereby opening a window to physics uniquely accessible with the HESR at FAIR. This includes a first measurement of the transversity distribution of the valence quarks in the proton, and a first measurement of the moduli and the relative phase of the time-like electric and magnetic form factors G{sub E,M} of the proton. In polarized and unpolarized pp-bar elastic scattering open questions like the contribution from the odd charge-symmetry Landshoff-mechanism at large |t| and spin-effects in the extraction of the forward scattering amplitude at low |t| can be addressed.
Nonlinear distortion added by the loudspeaker in a hearing aid lowers the signal-to-noise ratio and may degrade the hearing aid user's ability to understand speech. The balancedarmature- type loudspeakers, predominantly used in hearing aids, are inherently nonlinear devices, as any displacement of the loudspeaker diaphragm inevitably changes the magnetic and electrical characteristics of the loudspeaker. A numerical time-domain model capable of describing these nonlinearities is presented. By simulation it is demonstrated how the output distortion could potentially be reduced significantly through careful design of the mechanical properties of the armature.
Several short model SSC 50 mm bore dipoles are being built and tested at Fermilab. Mechanical design of these magnets has been determined from experience involved in the construction and testing of 40 mm dipoles. Construction experience includes coil winding, curing and measuring, coil end part design and fabrication, ground insulation, instrumentation, collaring and yoke assembly. Fabrication techniques are explained and construction problems are discussed. Similarities and differences from the 40 mm dipole tooling and management components are outlined. Test results from the first models are presented. 19 refs., 12 figs.
The spherical harmonic analysis of cosmic ray neutron data from the worldwide network neutron monitor stations during the years 1966 to 1969 was carried out. The second zonal harmonic component obtained from the analysis corresponds to the Pole-Equator anisotropy of the cosmic ray neutron intensity. Such an anisotropy makes a semiannual variation. In addition to this, it is shown that the Pole-Equator anisotropy makes a variation depending on the interplanetary magnetic field (IMF) sector polarities around the passages of the IMF sector boundary. A mechanism to interpret these results is also discussed.
A 37-year-old military mechanic presented to our institution with a chronic history of a slowly enlarging left elbow antecubital fossa mass. There was no history of other chronic illness or trauma. Magnetic resonance imaging (MRI) and excisional biopsy revealed fatty villi and synovial inflammation within the left bicipitoradial bursa, consistent with lipoma arborescens. Four years later the patient presented with a 6-month history of swelling at the antecubital fossa of the opposite elbow. Diagnostic computed tomography and MRI examinations were performed. The surgical and pathologic findings confirmed the imaging diagnosis of lipoma arborescens at the right bicipitoradial bursa. (orig.)
Characteristics of pressure drop and heat transfer have been investigated for a lithium single-phase flow and a helium-lithium two-phase flow in a horizontal conducting circular channel in the presence of a uniform transverse magnetic field up to 1.4 T as related to the lithium cooling for magnetic-confinement fusion reactors. By the application of the magnetic field to the lithium single-phase flow, remarkable heat transfer enhancement has been observed at the top wall due to the suppression of the mixed convection occurring in the low Peclet number range, while appreciable heat transfer deterioration appeared in the high Peclet number range. It has been confirmed that the helium-lithium two-phase flow can reduce the high magnetohydrodynamic (MHD) pressure drop in a lithium single-phase flow, and it can provide much better heat transfer performance than that in a helium single-phase flow. In the presence of the ...
1 Candoxin (MW 7334.6), a novel toxin isolated from the venom of the Malayan krait Bungarus candidus, belongs to the poorly characterized subfamily of nonconventional three-finger toxins present in Elapid venoms. The current study details the pharmacological effects of candoxin at the neuromuscular junction. 2 Candoxin produces a novel pattern of neuromuscular blockade in isolated nerve-muscle preparations and the tibialis anterior muscle of anaesthetized rats. In contrast to the virtually irreversible postsynaptic neuromuscular blockade produced by curaremimetic alpha-neurotoxins, the neuromuscular blockade produced by candoxin was rapidly and completely reversed by washing or by the addition of the anticholinesterase neostigmine. 3 Candoxin also produced significant train-of-four fade during the onset of and recovery from neuromuscular blockade, both, in vitro and in vivo. The fade phenomenon has been attributed to a blockade of putative presynaptic nicotinic ...
MnO powder materials are investigated as anode active materials for Li-ion batteries. Lithium is stored reversibly in MnO through conversion reaction and interfacial charging mechanism, according to the results of ex situ XRD, TEM and galvanostatic intermittent titration technique. A layer of the solid electrolyte interphase with a thickness of 20-60 nm is covered on MnO particles after full insertion. MnO powder materials show reversible capacity of 650 mAh g{sup -1} with average charging voltage of 1.2 V. It can deliver 400 mAh g{sup -1} at a rate of 400 mA g{sup -1}. The cyclic performance of MnO is improved significantly after decreasing particle size and coating with a layer of carbon. Among observed transition metal oxides, MnO shows relatively lower voltage hysteresis (<0.7 V) between the discharging and the charging curves at 0.05 C. In addition to its environmental benign feature and high density (5.43 g ...
Complete text of publication follows. In order to extend the capabilities of the electron cyclotron resonance (ECR) ion source (ECRIS) of ATOMKI it has been transformed into a special plasma facility [1,2]. The transformation is reversible and was simply done by changing several main components of the ion source by new ones, namely: the hexapole magnet, the plasma chamber and the microwave source. The basic requirements of the transformation were: (1) most parts of the present ECRIS should be used in the new assembly in the same way and (2) the transformation time between the two operation modes should not be more than 2-3 days (in both directions). The following sub-systems are used identically in both configurations: solenoid coils, vacuum system, gas dosing system, ovens, probes. The extraction optics and beam transport system can also be used in the new configuration to check the components and charge-state of the plasma. A new, large, but ...
Ultraviolet (UV) photoirradiation of Ag(I) compounds in the presence of an aqueous Triton X-100 solution has been exploited for the first time to prepare reproducible yellow silver hydrosol. The evolution of nanosized silver particles has been examined critically under the influence of different anions/ligands. Hence, time dependent evolution of silver hydrosol from different silver compounds in micelle via photochemical reduction is observed. Anions/ligands of precursor salts have been found to show profound influence (due to electron scavenging property, solubility, stability etc.) on the evolution route and efficiency of photochemical reduction of Ag(I) to Ag(O) in micelle and thereby classification of silver compounds becomes possible. Kinetic results reveal that the formation of silver particles proceeds via autocatalytic growth mechanism. The observed variation in rate constant values for the evolution of nanoparticles from different silver compounds have ...
A theoretical model, which describes subband gap photoexcitation involving localized electronic states, was developed. The escape probability of a charge carrier trapped in a localized state is considered via Poole-Frenkel, direct tunneling, or phonon-assisted tunneling processes, as competing escape mechanisms. Photoelectrochemical experiments were performed on the passive films formed on zirconium and amorphous iron-zirconium alloys and on pure HfO/sub 2/ films and HfO/sub 2/ films implanted with varying concentrations of xenon. These films were found to possess some degree of disorder depending on the substrate, the thickness of the film, and the extent of implantation. The spectral dependence of the photocurrent in all of the films studied is considerably different from what was found for crystalline passive films. The potential dependence of the photocurrent yields Poole-Frenkel behavior. Reverse tunneling processes were also observed at ...
The influence of membrane pH gradients on the transbilayer distribution of some common phospholipids has been investigated. The authors demonstrate that the transbilayer equilibrium of the acidic phospholipids egg phosphatidylglycerol (EPG) and egg phosphatidic acid (EPA) can be manipulated by membrane proton gradients, whereas phosphatidylethanolamine, a zwitterionic phospholipid, remains equally distributed between the inner and outer monolayers of large unilamellar vesicles (LUVs). Asymmetry of EPG is examined in detail and demonstrated by employing three independent techniques: ion-exchange chromatography, {sup 13}C NMR, and periodic acid oxidation of the (exterior) EPG headgroup. In the absence of a transmembrane pH gradient ({Delta}pH) EPG is equally distributed between the outer and inner monolayers of LuVs. When vesicles composed of either egg phosphatidylcholine (EPC) or DOPC together with 5 mol % EPG are prepared with a transmembrane {Delta}pH. EPG equilibrates across the ...
Complete text of publication follows. The stability regime of the incommensurate phase of quartz is influenced by uniaxial stress. Hence, the phase transition can be induced under isothermal conditions by the application of external mechanical forces. Using real-time neutron scattering the time evolution of structural changes is investigated id detail during stress variations. The time dependent behaviour of the satellite reflection is compared with that one of the fundamental Bragg reflection which - via primary extinction - gives information about the perfection of the crystal. On increasing stress the perfection of the lattice is destroyed immediately while the modulated structure is built up with a delay of about 1 s. Decreasing the stress leads to a reverse behaviour. Moreover, there is evidence that under periodical load residual non-relaxed strain fields survive leading to a different temperature dependence as compared to static ...
Past elastic-plastic fracture studies for leak-before-break (LBB) assessment of low alloy steel pipings have been focused mostly on the behavior of base metals and their weld metals. In contrast, the heat-affected zone (HAZ) of a welded pipe has not been studied in detail primarily because the size of the HAZ is too small to make specimens for mechanical properties measurements. In this study, microstructural analyses, microhardness tests, tensile tests and J-R tests have been conducted as a function of distance from a fusion line and temperature for HAZ materials of SA106Gr.C low alloy piping steels. For the ferrite-pearlite steels such as SA106Gr.C, the HAZ specimens showed a higher yield strength and fracture toughness compared with those of its base metal. These characteristics, despite of grain coarsening, can be explained by cleaner microstructures of HAZ materials with a finer morphology of carbides compared with pearlitic-ferritic base metals. However, the ...
Si/Ni alloy and graphite composites were synthesized using arc-melting followed by high energy mechanical milling (HEMM). Alloy particles comprising of NiSi2, NiSi and Si phases were distributed finely and uniformly on the surface of graphite in the composites obtained after Hem. The composite containing 60 wt.% of Si/Ni alloy exhibited a stable capacity of ?780 mAh/g. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that some bonds were formed between alloy and graphite after HEMM, which appeared to retain the electrical connection between alloy and graphite during cycling. X-ray diffraction (XRD) analysis indicated that NiSi2 and NiSi phases, which acted as an inactive alloy matrix remained invariant during charge and discharge. In addition to NiSi2 and NiSi phases, disordered graphite layers also played the role of media for the accommodation of large volume change of Si during cycling. The large reversible capacity and good ...
Efflux of dopamine through the dopamine transporter (DAT) is critical for the psychostimulatory properties of amphetamines, but the underlying mechanism is unclear. Here we show that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) plays a key role in this efflux. CaMKIIalpha bound to the distal C terminus of DAT and colocalized with DAT in dopaminergic neurons. CaMKIIalpha stimulated dopamine efflux via DAT in response to amphetamine in heterologous cells and in dopaminergic neurons. CaMKIIalpha phosphorylated serines in the distal N terminus of DAT in vitro, and mutation of these serines eliminated the stimulatory effects of CaMKIIalpha. A mutation of the DAT C terminus impairing CaMKIIalpha binding also impaired amphetamine-induced dopamine efflux. An in vivo role for CaMKII was supported by chronoamperometry measurements showing reduced amphetamine-induced dopamine efflux in response to the CaMKII inhibitor KN93. Our data suggest that CaMKIIalpha binding ...
Radiation necrosis of normal CNS tissue represents one of the main risk factors of brain irradiation, occurring more frequently and earlier at higher total doses and higher doses per fraction. At present, it is believed that the necrosis results due to increasing capillary permeability caused by cytokine release leading to extracellular edema. This process is sustained by endothelial dysfunction, tissue hypoxia, and subsequent necrosis. Consequently, blocking the vascular endothelial growth factor (VEGF) at an early stage could be an option to reduce the development of radiation necrosis by decreasing the vascular permeability. This might help to reverse the pathological mechanisms, improve the symptoms and prevent further progression. A patient with radiation-induced necrosis was treated with an anti-VEGF antibody (bevacizumab), in whom neurologic signs and symptoms improved in accordance with a decrease in T1-weighted fluid-attenuated ...
Magnetic separation of several classes of antibiotics was investigated using electrochemical magnetic seeding. Electrocoagulation with a sacrificial anode followed by addition of magnetite particles was applied for the magnetic seeding of antibiotics. With electrochemical magnetic seeding using an iron anode, tetracycline antibiotics (oxytetracycline, chlortetracycline, doxycycline and tetracycline) and cephalosporin antibiotic (cefdinir) were rapidly removed from synthetic wastewater by magnetic separation using a neodymium magnet. Iron and aluminium anodes were suitable for magnetic seeding of the antibiotics. The results indicated that the ability of antibiotics to form strong complex with iron and aluminium allowed the higher removal by magnetic separation. This method would be appropriate for rapid treatment of ...
Glioblastoma multiforme is the most aggressive form of human brain tumor, which has no effective cure. Previously, we have demonstrated that overexpression of the C-terminal fragment of the human telomerase reverse transcriptase (hTERTC27) inhibits the growth and tumorigenicity of human cervical cancer HeLa cells. In this study, the therapeutic effect and molecular mechanisms of hTERTC27-mediated cancer gene therapy were further explored in vivo in established human glioblastoma xenografts in nude mice. We showed that intratumoral injection of adeno-associated virus carrying hTERTC27 (rAAV-hTERTC27) is highly effective in reducing the growth of the subcutaneously transplanted glioblastoma tumors. Histological analyses showed that rAAV-hTERTC27 treatment leads to profound necrosis, apoptosis, infiltration of polymorphonuclear neutrophils and reduced microvessel density in the tumor samples. To study the molecular mechanism ...
A highly reliable control rod drive mechanism (CRDM) installed inside the reactor vessel has developed for use of an advanced marine reactor. This CRDM contributes to compactness and simplicity of the reactor system, and it can eliminate the possibility of a rod ejection accident. The CRDM works in the high temperature and high pressure water - 310degC and 12 MPa, the same atmosphere as the primary loop. Driving force is produced by a synchronous motor with the rotor of a permanent magnet, which has been developed. An innovative latch mechanism using separable ball nuts can latch driving shaft connecting the control rod and de-latch it for scram. The rod position detector using a magnetostrictive wire type sensor on the principle of Wiedeman effect has been developed, accuracy of which is verified to have a detecting error within 1.2 mm. Ball bearings for thrust and radial supports in rotation have been developed to be ...
The accepted model of retroviral reverse transcription includes a circular DNA intermediate which requires strand displacement synthesis for linearization and creation of an integration-competent, long...Full Text Available
ObjectiveTo implement a role-reversal exercise to increase first-year pharmacy students' awareness of communication barriers in the health care setting, especially for deaf and hard-of-hearing...Full Text Available
Reverse engineering of gene regulatory networks has been an intensively studied topic in bioinformatics since it constitutes an intermediate step from explorative to causative gene expression...Full Text Available
A rapid loss of far red light (FR) reversibility of red-light (R) stimulated elongation of maize coleoptile sections was observed. Reversal was not possible when the interval between R and FR treatment...Full Text Available
Reversion-induced LIM protein (RIL) is a member of the ALP (actinin-associated LIM protein) subfamily of the PDZ/LIM protein family. RIL serves as an adaptor protein and seems to regulate cytoskeletons....Full Text Available
The author demonstrates through a specific example that it is possible to extract rotational energy from a Kerr source (in principle, of arbitrary size but not turned black) through a reversible process by suitably injecting tachyons. (Auth.).
PurposeWound infection after an ileostomy reversal is a common problem. To reduce wound-related complications, purse-string skin closure was introduced as an alternative to conventional...Full Text Available
We offer a plausible interpretation of some experiments on the reversal of neoplastic transformations in plants. We suggest that normal cells and tumorous cells represent multiple stable-steady states...Full Text Available
Purpose: Reverse helical cone-beam computed tomography (CBCT) is a scanning configuration for potential applications in image-guided radiation therapy in which an accurate anatomic image...Full Text Available
Fe-doped MnO2 with a hollow sea urchin-like ball chain shape was first synthesized under a high magnetic field of 10 T. The formation mechanism was investigated and discussed in detail. The synthesized samples were characterized by XRD, SEM, TEM, EMPA, and vector network analysis. By doping MnO2 with Fe, the relative complex permittivity of MnO2 and its corresponding loss tangent clearly decreases, but its relative complex permeability and its corresponding loss tangent markedly increases. Moreover, the theoretically calculated values of reflection loss show that with increasing the Fe content, the as-prepared Fe-doped MnO2 exhibits good microwave absorption capability. -- Graphical Abstract: Fe-doped MnO2 with a hollow sea urchin-like ball chain shape was first synthesized in a high magnetic field of 10 T via a simple chemical process. Display Omitted Highlights: ? Fe-doped MnO2 with a hollow sea urchin-like ball chain ...
Biased above threshold (VT), pulsed photocurrent (u) measurements on windowed silicon Pd gate MOS capacitors are shifted (DV) negatively by H2/N2, whereas Au gates shift positively under NO2/air. Below VT, the shifts are reversed by adjustments of interface state population. Minor temperature increases may coax the device from inversion to depletion, inducing sign reversal of the chemical response.
Dynamic deformation and recovery responses of red blood cells (RBCs) to a cyclically reversing shear flow generated in a 30-μm clearance, with the peak shear stress of 53, 108,...Full Text Available
Magnetic fields correlated on several kiloparsec scales are seen in spiral galaxies. Their origin could be due to the winding up of a primordial cosmological field or due to amplification of a small seed field by a turbulent galactic dynamo. Both options have difficulties: There is no known battery mechanism for producing the required primordial field. Equally the turbulent dynamo may self destruct before being able to produce the large scale field, due to excess generation of small scale power. The current status of these difficulties is discussed. The resolution could depend on the nature of the saturated field produced by the small scale dynamo. We argue that the small scale fields do not fill most of the volume of the fluid and instead concentrate into intermittent ropes, with their peak value of order equipartition fields, and radii much smaller than their lengths. In this case these fields neither drain significant energy from the ...
The effect of the external pH on the intracellular pH in mung bean (Vigna mungo (L.) Hepper) root-tip cells was investigated with the T P nuclear magnetic resonance (NMR) method. The T P NMR spectra showed three peaks caused by cytoplasmic G-6-P, cytoplasmic Psub(i) and vacuolar Psub(i). The cytoplasmic and vacuolar pHs could be determined by comparing the Psub(i) chemical shifts with the titration curve. When the external pH was changed over a range from pH 3 to 10, the cytoplasmic pH showed smaller changes than the vacuolar pH, suggesting that the former is regulated more strictly than the latter. The H -ATPase inhibitor, DCCD, caused the breakdown of the mechanism that regulates the intracellular pH. H -ATPase appears to have an important part in the regulation of the intracellular pH.
The Electromagnetic Fluctuations (EMF) diagnostic will be used to monitor ion fluctuations which could be unstable in MFTF-B. Each probe assembly includes a high impedance electrostatic probe to measure potential fluctuations, and a group of nested, single turn loops to measure magnetic fluctuations in three directions. Eventually, more probes and loops will be added to each probe assembly for making more detailed measurements. The sensors must lie physically close to the plasma edge and are radially positionable. Also, probes at separate axial locations can be positioned to connect along the same magnetic field line. These probes are similar in concept to the rf probes used on TMX, but the high thermal load for 30-second shots on MFTF-B requires a water-cooled design along with temperature monitors. Each signal channel has a bandwidth of .001 to 150 MHz and is monitored by up to four different data channels which obtain amplitude and frequency ...
To study #beta# #reversible# #omega#-transformation in pseudo-#beta#-titanium alloy VT30, doped by hydrogen, methods of X-ray diffraction and thermodifferential analyses are used. It is established that in the process of heating of the hardened alloy from 0.004-0.1% H first formation and then dissolution of #omega# phase take place. An increase in hydrogen content to 0.1% decreases thermal effect of the processes and does not affect the temperature of #beta# #reversible# #omega#-transformation. Introduction of hydrogen in the concentration of 0.2% and higher suppresses completely #beta# #reversible# #omega# - transformation. A decrease in heating rate displaces #beta# #reversible# #omega#-transformation to lower temperatures.
This paper addresses the stability aspects of several successful dc superconducting magnets such as large bubble chamber magnets, and magnets for the Mirror Fusion Test Facility and MHD Research Facility. Specifically, it will cover Argonne National Laboratory 12-Foot Bubble Chamber magnets, the 15-foot Bubble Chamber magnets at Fermi National Laboratory, the MFTF-B Magnet System at Lawrence Livermore National Laboratory, the U-25B Bypass MHD Magnet, and the CFFF Superconducting MHD magnet built by Argonne National Laboratory. All of these magnets are cooled in pool-boiling mode. Magnet design is briefly reviewed. Discussed in detail are the adopted stability critera, analyses of stability and disturbance, stability simulation, and the final results of magnet ...
We investigate the magnetic braking of the core of an axisymmetric cloud whose rotation axis is parallel to the mean direction of the magnetic field. (author).
Checks are performed on the alignment of the magnets in the LHC tunnel. It is vital that each magnet is placed exactly where it has been designed so that the path of the beam is precisely controlled.
The magnetic fluid is a colloidal suspension of magnetite in kerosene, prepared by a low-cost process. Separation is accomplished in an open trough filled with magnetic fluid. A magnetic field is established in the fluid, by energizing an electromagnet having poles on each side of the trough. Due to the design of the magnet poles and air gaps, the magnetic field is strongest at the bottom, about 10,000 oersteds, and uniformly decreases in strength to about 2000 oersteds at the top of the fluid. Therefore, the magnetic field gradient increases with depth. The magnetic force attracts the entire separation medium (magnetic fluid) creating a reaction force of equal magnitude and acting in the opposite direction. This reaction created within a magnetic fluid/magnetic field combination ...
Textured silicon nitride (Si_3N_4) has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si_3N_4, with emphasis on the anisotropic and abnormal grain growth of #beta#-Si_3N_4, texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW) and templated grain growth (TGG). The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for #beta#-Si_3N_4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical ...
Power spectral analysis of cosmic ray intensity recorded by neutron monitors at Calgary and Deep River, Alberta, was carried out over a wide range of frequencies from 3 {times} 10{sup {minus}9} Hz to 6 {times} 10{sup {minus}6} Hz during the epoch 1965-1989 and revealed different behavior of the power spectral density for the three ranges of frequency domains. At low frequencies corresponding to the periodicity T {approx} 20 months the power spectrum shows an abrupt change in the level and profile of power spectral density (PSD). This indicates that the processes responsible for the long period variations are different from the one which causes short-period variations. At middle frequencies corresponding to periodicities between 6 and 18 months, the PSD indicates that the periodicities are not stable and show a transient character over the entire epochy of analysis. The PSD for periods T {approx} 27 days indicates an 11 year recurring tendency related to solar activity. The PSD for ...
The unsteady aerodynamic forces of a model fruit fly wing in flapping motion were investigated by numerically solving the Navier-Stokes equations. The flapping motion consisted of translation and rotation [the translation velocity (u(t)) varied according to the simple harmonic function (SHF), and the rotation was confined to a short period around stroke reversal]. First, it was shown that for a wing of given geometry with u(t) varying as the SHF, the aerodynamic force coefficients depended only on five non-dimensional parameters, i.e. Reynolds number (Re), stroke amplitude (Phi), mid-stroke angle of attack (alpha(m)), non-dimensional duration of wing rotation (Delta tau(r)) and rotation timing [the mean translation velocity at radius of the second moment of wing area (U), the mean chord length (c) and c/U were used as reference velocity, length and time, respectively]. Next, the force coefficients were investigated for a case in which typical values of these ...
The results of the thermo-hydro-mechanical (THM) study of the FEBEX bentonite performed during FEBEX II are presented. The laboratory test program continued in part with the works carried out during FEBEX I, particularly in activities related to tests aimed to the calibration of the models, the acquisition of parameters by back-analysis and the improvement of the knowledge on the behaviour of expansive clays. But the program has also included tests on new areas: investigations about the influence of the microstructure changes in bentonite, of temperature and of the solute concentration on the behaviour of clay. Besides, several tests were proposed in order to understand the unexpected behaviour observed in the mock-up test, towards the end of year 2. Temperature effects on water retention curves in confined and unconfined conditions were determined, and swelling pressure, hydraulic conductivity and swelling and consolidation strains as a function of temperature ...
There is evidence that aged normal subjects have more difficulty in achieving automaticity than young subjects. The underlying central neural mechanism for this phenomenon is unclear. In the present study, functional magnetic resonance imaging (fMRI) was used to investigate the effect of normal ageing on automaticity. Aged healthy subjects were asked to practice self-initiated, self-paced, memorized sequential finger movements with different complexity until they could perform the tasks automatically. Automaticity was evaluated by having subjects perform a secondary task simultaneously with the sequential movements. Although it took more time, most aged subjects eventually performed the tasks automatically at the same level as the young subjects. Functional MRI results showed that, for bot...
We consider a SQUID ring inductively coupled to an electromagnetic field mode, both treated quantum mechanically. We demonstrate a method for creating a maximally entangled state between the ring and the field mode. Our method utilises a non-adiabatic external magnetic flux pulse to move into and out of a transition region. Hence, our approach is fundamentally different to techniques based on Landau-Zener tunnelling that can also be used to achieve similar results. Our analysis is extended to include the effects of coupling the system to a dissipative environment. With this model we show that although such an environment makes a noticeable difference to the time evolution of the system, it need not destroy the entanglement of this coupled system over time scales required for quantum technologies.
We provide a brief review of our recent results from optically detected magnetic resonance studies of grown-in non-radiative defects in two most important dilute nitride systems-Ga(In)NAs grown on GaAs substrates and Ga(Al,In)NP grown on Si and GaP substrates. These results have led to the identification of defect complexes in the alloys, involving intrinsic defects such as As_G_a antisites and Ga_i self-interstitials. They have also shed light on formation mechanisms of the defects and on their role in non-radiative carrier recombination that is harmful to the performance of potential optoelectronic and photonic devices based on these dilute nitrides.
Because power requirements in induction heating applications are largely dependent on the physical properties of the product to be heated, inducting, heating is mainly used in steelwork applications, for the manufacture of finished or semi-finished parts. Applications here cover five main types of steelworks operation: smelting, heating prior to forming, heat treatment, surface treatment, and assembly process. At the same time, technological progress has opened up innovative applications in sectors such as chemical and agro-food industries. Other emerging applications for induction include direct forming of liquid metal, wholly or partially replacing mechanical transformations on solid metal. Techniques include electromagnetic forming, continuous cold-crucible casting, electromagnetic mixing, flow control by continuous magnetic field, and production of intense sliding fields (pumps, flow regulation). (author)
The advance in laser-plasma acceleration techniques pushes the regime of the resulting accelerated particles to higher energies and intensities. In particular the upcoming experiments with the FLAME laser at LNF will enter the GeV regime with almost 1nC of electrons. From the current status of understanding of the acceleration mechanism, relatively large angular and energy spreads are expected. There is therefore the need to develop a device capable to measure the energy of electrons over three orders of magnitude (few MeV to few GeV) under still unknown angular divergences. Within the PlasmonX experiment at LNF a spectrometer is being constructed to perform these measurements. It is made of an electro-magnet and a screen made of scintillating fibers for the measurement of the trajectories of the particles. The large range of operation, the huge number of particles and the need to focus the divergence present unprecedented challenges in the ...
Moessbauer spectra of the imitative ancient Jun porcelain indicate that the glaze and body materials contain Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4} and structural iron. It is clear that during the firing process, the glaze undergoes dehydration, dehydroxylation, vitrification and recrystallization. The Fe{sup 2+} quadrupole splitting value of the paramagnetic peak of the body material is high even at low firing temperatures. For the body material, the distinction between dehydration and dehydroxylation is not clear. The changes of magnetism of the glaze and body materials in the firing process and the coloring mechanism of the sky-blue Jun porcelain are analyzed in the present paper. (orig.)
The physics of density limit phenomena in toroidal helical plasmas based on an analytic point model of toroidal plasmas is discussed. The combined mechanism of the transport and radiation loss of energy is analyzed, and the achievable density is derived. A scaling law of the density limit is discussed. The dependence of the critical density on the heating power, magnetic field, plasma size and safety factor in the case of L-mode energy confinement is explained. The dynamic evolution of the plasma energy and radiation loss is discussed. Assuming a simple model of density evolution, of a sudden loss of density if the temperature becomes lower than critical value, then a limit cycle oscillation is shown to occur. A condition that divides the limit cycle oscillation and the complete radiation collapse is discussed. This model seems to explain the density limit oscillation that has been observed on the W7-AS stellarator. (author)
Nanocapsules coated by medicinal plants have many applications in drug manufacturing. Medicinal plants can be loaded on nanocapsules with polyesteric triblock copolymer poly ethylene glycol-poly butylene adipate-poly ethylene glycol (PEG-PBA-PEG) as shell and olive oil can be introduced as a core of nanocapsules by a method known as polymer deposition solvent evaporation method. In this research, first, certain amount of polymer, Matricaria recutita extract and olive oil were mixed with acetone and then, water was added to the solution using magnetic stirrer. After which the acetone was removed by vacuuming and finally nanocapsules were found by freezing-drier. The study showed the size of nanocapsules depends on variety of factors such as the ratio of polymer to oil and concentration of p...
The effect of treatment of Na-forms of zeolites with HCl solutions and of heat treatment of their NH/sub 4/-forms on the stability of aluminum-oxygen tetrahedra has been studied in this work by high-resolution NMR on /sup 29/Si nuclei, using the synthetic zeolites X, Y, and M (mordenite) as the objects of the study. The exchange capacity with respect to Na/sup +/ ions was determined by analyzing the equilibrium solutions after contact of the samples with 0.5 NH/sub 4/Cl solution on a flame photometer. The high-resolution /sup 29/Si NMR spectra of polycrystalline samples were recorded on an SKhR-200 spectrometer with a superconducting solenoid at a frequency of 39.75 MHz with ultrafast mechanical rotation (3 kHz) of the sample at the magic angle to the external magnetic field. The results obtained are given.
Nd{sub 40}Fe{sub 30}Al{sub 10}Co{sub 15}B{sub 5} alloys were fabricated by high energy ball milling method under various conditions. Microstructure of the alloys was investigated by X-ray diffraction and electron microscopy techniques. Magnetic properties were characterized by hysteresis and thermomagnetic measurements. The high coercive fields up to 2.36 T have been observed on the samples consisting of Nd{sub 2}(Fe,Co,Al){sub 14}B, Nd{sub 6}(Fe,Co,Al){sub 14} and Nd crystallites imbedded in a residual amorphous matrix.
Coilguns have the ability to provide magnetic pressure to projectiles which results in near constant acceleration. However, to achieve this performance and control projectile hearing, significant constraints are placed on the design of the coils. We are developing coils to produce an effective projectile base pressure of 100 MPa (1kbar) as a step toward reaching base pressures of 200 MPa. The design uses a scalable technology applicable to the entire range of breech to muzzle coils of a multi-stage launcher. This paper presents the design of capacitor-driven coils for launching nominal 50 mm, 350 gram projectiles. Design criteria, constraints, mechanical stress analysis, launcher performance, and test results are discussed.
We have constructed a mathematical model that describes the coherent spontaneous radiation of a macroscopically filled exciton mode. We have demonstrated qualitatively ways in which a coherent subsystem of excitons can be formed. When this occurs under the influence of an external coherent source, exciton free induction occurs, while in the case of a spontaneous transition of the excitons to a coherent state through freezing of the reservoir of intermolecular interactions superradiance occurs. We have concluded that superradiance in the system of Frenkel excitons is possible under the influence of the non-Dicke mechanisms of self-induction of correlations, when the dipole transition moments of the individual atoms are coupled into a single macroscopic effective spin through their electrostatic interaction, this being analogous to the ordering of magnetic dipole moments in a ferromagnet.
Course website from Cambridge on ceramic materials. This site contains eight lectures in PDF format (Adobe Reader required), two question sheets, five practicals (including answers), digital movies and further useful links. "There is a strong relationship between the structure of a material and its physical properties. The properties of a material whether mechanical, electrical, optical or magnetic, determine how it can be used in practical applications. In this course, the focus is on the structure / property relationship for ionic materials with electrical properties utilised in various transducer devices. The materials considered include perovskites, which have special polarisation properties exploited in ferroelectric, pyroelectric and piezoelectric devices. Other oxides, such as zirconia, have structures permitting rapid diffusion of ions, making them suitable for use in sensors, fuel cells and batteries. The scientific principles ...
This paper explores for the first time the post-radiation-induced-graft polymerization on solid substrate using reversible addition-fragmentation transfer (RAFT) mechanism. Radiation-induced graft polymerization onto polymers is a potentially interesting technique to create easily new materials from highly resistant polymers, e.g. surface graft polymerization of acrylic acid (AA) onto poly(vinylidene difluoride) (PVDF) improves its surface properties without losing its excellent mechanical properties. As a consequence of the radical nature of the polymerization processes it is difficult to control molecular weight of grafted chains, and therefore design and standardize the properties of the final product. RAFT polymerization is a suitable method to obtain monodisperse polymers. The ability of the RAFT agents to control the polymer chain length could be an interesting approach to improve the grafted polymers obtained by ...
Rare Earth Cobalt (REC) permanent magnets have unique properties that permit solutions to some optical tasks that cannot be accomplished with conventional magnets. A review of design and of performance characteristics of these magnets includes an analytical description of the three dimensional fringe fields of REC quadrupoles.
Polysaccharides like cellulose and chitosan are known for their filmic properties. This paper concerns the synthesis and the study of chitosan-based polymer electrolytes. A preliminary work concerns the study of glucosamine reactivity. The poly-condensation of chitosan ethers (obtained by reaction with ethylene oxide or propylene oxide) with bifunctional and monofunctional oligo-ethers leads to the formation of thin lattices (10 {mu}m) having excellent mechanical properties. The presence of grafted polyether chains along the polysaccharide skeleton allows to modify the vitreous transition temperature and the molecular disorder of the system. Two type of polymer electrolytes have been synthesized: electrolytes carrying a dissolved alkaline metal salt and ionomers. The analysis of their thermal, dynamical mechanical, nuclear magnetic relaxation, electrical, and electrochemical properties shows that this new class of polymer ...
BC Hydro recently conducted a demonstration test of a bearing condition monitor. The test, at the 529-MW Kootenay Canal project, proved the ability of the monitor to detect machine condition faults. The capability to detect changing conditions during normal operation of hydroelectric machines gives hydro plant owners the opportunity to anticipate needed maintenance and ultimately to reduce the number of equipment failures. BC Hydro intends to install bearing condition monitors, as well as windings monitors, brushgear monitors, environmental monitors, and other selected systems in as many as 46 of its hydro generators. BC Hydro analyzed forced outages between 1985 and 1989 in its hydro system to identify which parts of a generating unit resulted in the highest number of hours of outage. From there, the utility has formulated a concept for a machine condition monitoring system. To keep the system cost effective, it will be developed in modules. In this way, users can pick and choose from ...
... in the design of such devices as fusion reactors, magnetohydrodynamic generators, magnetically levitated vehicles, magnetic forming devices, and ...
The critical currents of A-15 phase Nb(,3)Sn, V(,3)Si, Nb(,3)Ge, V(,3)Ga, and Nb-Sn with a few at.% Ga and Al(,2)O(,3) have been measured at temperatures up to T(,c) and in magnetic fields up to 8T to study fundamental flux pinning interactions as a function of defect size and density. The samples are electron beam evaporated films typically 2 (mu)m thick. Their particular usefulness for this study is that they span the clean to dirty limits and their normal state resistivity and grain size can be controlled by deposition parameters. The grain boundaries are the defects most responsible for flux pinning. The electron scattering mechanism is based on the local change in the coherence length due to increased conduction electron scattering and is chosen from among several possible mechanisms to calculate the elementary pinning force at a grain boundary. A direct summation of the elementary pinning force of each boundary is ...
This paper traces the development and progress of magnetic suspension systems and magnetic bearings in the USSR. The paper describes magnetic bearings for turbomachines, magnetic suspension systems for vibration isolation, some special measuring devices, wind tunnels, and other applications. The design, principles of operation, and dynamic characteristics of the system are presented.
In order to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices, a symposium was held. The proceedings are presented. The sessions covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems.
Assessment of the roles of the carboxyl-terminal #beta#146 histidyl residues in the alkaline Bohr effect in human and normal adult hemoglobin by high-resolution proton nuclear magnetic resonance spectroscopy requires assignment of the resonances corresponding to these residues. By a careful spectroscopic study of human normal adult hemoglobin, enzymatically prepared des(His146#beta#)-hemoglobin, and the mutant hemoglobins Cowtown (#beta#146His #-># Leu) and York (#beta#146His #-># Pro), the authors have resolved some of these conflicting results. By a close incremental variation of pH over a wide range in chloride-free 0.1 M N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid buffer, a single resonance has been found to be consistently missing in the proton nuclear magnetic resonance spectra of these hemoglobin variants. The results indicate that the contribution of the #beta#146 histidyl residues is 0.52 H"+/hemoglobin tetramer at pH ...
The marked difference between the intra- and extracellular "3"1P NMR chemical shifts of various phosphoryl compounds when added to a red cell suspension may be largely understood in terms of the effects of hemoglobin on the "3"1P NMR chemical shifts. The presence of [oxy- or (carbonmonoxy)-] hemoglobin inside the red cell causes the bulk magnetic susceptibility of the cell cytoplasm to be significantly less than that of the external solution. This difference is sufficient to account for the difference in the intra- and extracellular chemical shifts of the two phosphate esters trimethyl phosphate and triethyl phosphate. However, in the case of the compounds dimethyl methylphosphonate, diethyl methylphosphonate, and trimethylphosphine oxide as well as the hypophosphite, phenylphosphinate, and diphenylphosphinate ions, hemoglobin exerts an additional, much larger, effect, causing the "3"1P NMR resonances to shift to lower frequency in a manner that cannot be accounted ...
Long-term modulation of galactic cosmic rays in interplanetary magnetic field (IMF) turbulence is a fundamental subject for understanding the connection between cosmic ray transport and solar activity. The discovery of a new cosmic ray modulation phenomenon is reported. Analysis of neutron monitor data has revealed that the difference in amplitude of the cosmic ray diurnal anisotropy for IMF sectors directed toward and away from the Sun displays a solar cycle variation. Neutron monitor data recorded at Climax, Deep River, Hyancayo, Kiel, Mt. Washington, and Swarthmore/Newark over the period 1957 to 1988 show that the amplitude difference varied between approximately 0.1 to -0.1 percent, with peaks in 1960, 1972, and 1982. A theoretical expression for this difference was derived from a three-dimensional model. Analysis also showed that the latitudinal density gradient of cosmic rays changed between 1.6 and -1.6 percent/AU with a solar cycle variation, which may ...
The subjective experience of one's environment is constructed by interactions among sensory, cognitive, and affective processes. For centuries, meditation has been thought to influence such processes by enabling a nonevaluative representation of sensory events. To better understand how meditation influences the sensory experience, we used arterial spin labeling functional magnetic resonance imaging to assess the neural mechanisms by which mindfulness meditation influences pain in healthy human participants. After 4 d of mindfulness meditation training, meditating in the presence of noxious stimulation significantly reduced pain unpleasantness by 57% and pain intensity ratings by 40% when compared to rest. A two-factor repeated-measures ANOVA was used to identify interactions between meditation and pain-related brain activation. Meditation reduced pain-related activation of the contralateral primary somatosensory cortex. Multiple regression ...
A non-contact method, using magnetic drag force principle, was proposed to design the braking systems to improve the shortcomings of the conventional braking systems. The extensive literature detailing all aspects of the magnetic braking is briefly reviewed, however little of this refers specifically to upright magnetic braking system, which is useful for industries. One of the major issues to design upright magnetic system is to find out the magnetic flux. The changing magnetic flux induces eddy currents in the conductor. These currents dissipate energy in the conductor and generate drag force to slow down the motion. Therefore, a finite element model is developed to analyze the phenomena of magnetic flux density when air gap and materials of track are varied. The verification shows the predicted magnetic flux is within ...
O close-quote Neil and Smith [T.M. O close-quote Neil and R.A. Smith, Phys. Plasmas 1, 8 (1994)] have argued that a pure electron plasma can be confined stably in a toroidal magnetic field configuration. This paper shows that the toroidal curvature of the magnetic field of necessity causes slow cross-field transport. The transport mechanism is similar to magnetic pumping and may be understood by considering a single flux tube of plasma. As the flux tube of plasma undergoes poloidal ExB drift rotation about the center of the plasma, the length of the flux tube and the magnetic field strength within the flux tube oscillate, and this produces corresponding oscillations in T_p_a_r_a_l_l_e_l and T_p_e_r_p_e_n_d_i_c_u_l_a_r. The collisional relaxation of T_p_a_r_a_l_l_e_l toward T_p_e_r_p_e_n_d_i_c_u_l_a_r produces a slow dissipation of electrostatic energy into heat and a consequent ...
Reverse osmosis is a simple process and has relatively high decontamination factor compared to other processes used for the treatment of radioactive liquid waste. Furthermore the quantity of secondary waste of this process is small. In this study, test solution containing nine elements such as cesium, strontium, cobalt etc. in chloride forms are treated by reverse osmosis. Permeate rate decreases as the increase of osmotic pressure of feed solution and is expressed by linear equation. Decontamination factor of cations of univalency is more than ten, and about one tenth of that of bivalency. Decontamination factors of all the elements used in this experiment are approximately estimated using the solution-diffusion model.
Reverse osmosis is a simple process and has relatively high decontamination factor comparing to other processes used for the treatment of radioactive liquid waste. Furthermore the quantity of secondary waste of this process is small. In this study, test solution containing nine elements such as cesium, strontium, cobalt etc. in chloride forms are treated by reverse osmosis. Permeate rate decreases as the increase of osmotic pressure of feed solution and is expressed by linear equation. Decontamination factor of cations of univalency is more than ten, and about one tenth of that of bivalency. Decontamination factors of all the elements used in this experiment are approximately estimated using the solution-diffusion model. (author).
VSP reverse-time migration is a well adaptable wave equation migration method. Its control equation not only describes all-direction propagation of seismic wave but also removes interbed multiples. Clearbout's image principle is generalized to determine image conditions, real VSP data are used to determine boundary condition, and two way reflection-free wave equation is solved by making reverse-time extrapolation. In each step of extrapolation, the migration value at relevant image point is obtained by using the image condition. The complete migration of a seismic section is achieved when reverse-time extrapolation reaches the minimum image time. In this paper it is proved theoretically and practically that this method is applicable to any velocity variation and makes the migrated section have both good resolution and high S/N ratio. Besides, this method results in high processing efficiency.
... Values of absorption maxima, X.nax, and associated molar extinction coefficients, c, as well as values of the n-octanol/water partition coefficient( ...
A rapid and highly reproducible chromatographic technique has been developed for analysis and purification of complex mixtures of oligoribonucleotides. The method utilizes a column of microparticulate...Full Text Available
The current therapy for extrinsic and intrinsic asthma, together with that of ‘wheezing bronchitis’, is presented, with special attention to bronchodilators and adrenocorticosteroids....Full Text Available
Orphan G protein-coupled receptors (GPCRs) are receptors lacking endogenous ligands. Found by molecular biological analyses, they became the roots of reverse pharmacology, in which receptors are attempted...Full Text Available
We describe the cloning and characterization of a mutated thermostable DNA polymerase from Thermus aquaticus (Taq) that exhibits an increased reverse transcriptase activity and is therefore designated for one-step PCR pathogen detection using established real-time detection methods. We demonstrate that this Taq polymerase mutant (Taq M1) has similar PCR sensitivity and nuclease activity as the respective Taq wild-type DNA polymerase. In addition, and in marked contrast to the wild-type, Taq M1 exhibits a significantly increased reverse transcriptase activity especially at high temperatures (>60degreeC). RNA generally hosts highly stable secondary structure motifs, such as hairpins and G-quadruplexes, which complicate, or in the worst case obviate, reverse transcription (RT). Thus, RT at hi...
... that range from relatively low frequency strong ground motion modeling [Vidale et al., 1985] to high frequency reverse time migration of seismic ...
6-Mercaptopurine (6-MP) inhibits the growth of. Escherichia coli B. Growth inhibition is ... reversed by subculture of the cells in 6-mercaptopurine- ...
To investigate the magnetic fluctuations and for further transport study, the poloidal and radial magnetic field measurement is conducted on the Sino United Spherical Tokamak (SUNIST). Auto-power spectral density indicates that the magnetic fluctuation energy mainly concentrates in the frequency region lower than 10 kHz. The magnetic field oscillations, which are characterized by harmonic frequencies of 40 kHz, are observed in the scrape-off layer; by contrast, in the plasma core, the magnetic fluctuations are of Gaussian type. The time-frequency profiles show that the poloidal magnetic fluctuations are temporally intermittent. The autocorrelation calculation indicates that the fluctuations in decorrelation time vary between the core and the edge. (authors)
Three-dimensional dynamics of a compact toroid (CT) plasmoid, which is injected into a magnetized target plasma region is investigated by using magnetohydrodynamic (MHD) numerical simulations. It is found that the process of the CT penetration into this region is much more complicated than what has been analyzed so far by using a conducting sphere (CS) model. The injected CT suffers from a tilting instability, which grows with the similar time scale as the CT penetration. The instability is accompanied by magnetic reconnection between the CT magnetic field and the target magnetic field, which disrupts the magnetic configuration of the CT. Magnetic reconnection plays a role to supply the high density plasma initially confined in the CT magnetic field into the target region. Also, the penetration depth of the CT high density plasma is ...
Potassium clusters arrayed in zeolite A are known to show ferromagnetic properties at low temperature. The origin of the spontaneous magnetization has been explained by a model of spin-canting in an antiferromagnetically ordered state. The direct information for the magnetic structure, however, has not been obtained so far. In the present work, we measure the neutron powder diffraction by using pulsed neutron source at KEK-KENS below and above the Curie temperature. No significant temperature-dependence was, however, obtained within the statistical errors, namely, magnetic scattering could not be detected separately. We also estimate the intensity of magnetic scattering by assuming some possible magnetic structures with considering the magnetic form factor of the cluster wave function. The intensity of magnetic scattering is estimated to be ...
Potassium clusters arrayed in zeolite A are known to show ferromagnetic properties at low temperature. The origin of the spontaneous magnetization has been explained by a model of spin-canting in an antiferromagnetically ordered state. The direct information for the magnetic structure, however, has not been obtained so far. In the present work, we measure the neutron powder diffraction by using pulsed neutron source at KEK-KENS below and above the Curie temperature. No significant temperature-dependence was, however, obtained within the statistical errors, namely, magnetic scattering could not be detected separately. We also estimate the intensity of magnetic scattering by assuming some possible magnetic structures with considering the magnetic form factor of the cluster wave function. The intensity of magnetic scattering is estimated to be ...
The cause of the Gulf War Syndrome may be related to soldiers being exposed to insecticides (e.g., permethrin (P)), insect repellents (e.g., N,N-diethyl-m-toluamide (DEET)), an organophosphate nerve agent simulant (e.g., diisopropyl fluorpohosphate (DFP)), and/or prophylactic treatment (e.g., pyridostigmine bromide (PB)) against potential nerve gas attacks. The purpose of this study was to assess the dermal disposition of [14C]permethrin in ethanol or ethanol:water (3:2) in the isolated perfused porcine skin flap (IPPSF) model with simultaneous dermal exposure to DEET or DFP. These IPPSFs were also simultaneously perfused arterially with or without PB, DFP, or DFP + PB. The results indicated that DFP + PB significantly increased [14C]permethrin absorption compared to controls (1.06% dose vs 0.14% dose). PB significantly increased [14C]permethrin disposition in the stratum corneum (SC) in aqueous mixtures only (9.40 vs 3.35% dose), while topical DEET or topical DFP reduced ...
In this paper, we report the electrochemical characteristics of a novel cathode material, Li{sub 2}CoPO{sub 4}F, prepared by solid-state reactions. The solid-state reaction mechanism involved in synthesizing the Li{sub 2}CoPO{sub 4}F also is analyzed in this paper. When cycled between 2.0 V and 5.0 V during cyclic voltammetry measurements, the Li{sub 2}CoPO{sub 4}F samples present one, fully reversible anodic reaction at 4.81 V. When cycled between 2.0 V and 5.5 V, peaks occurring at 4.81 V and 5.12 V in the first anodic scan evolved to one broad oxidative, mound-like pattern in subsequent cycles. Correspondingly, the X-ray diffraction (XRD) pattern of the Li{sub 2}CoPO{sub 4}F electrode discharged from 5.5 V to 2.0 V is slightly different from the patterns exhibited by a fresh sample and the sample discharged from 5.0 V to 2.0 V. This difference may correspond to a structural relaxation that appears above 5 V. In the constant current cycling ...
Bariatric surgical procedures have become important therapeutic options for treatment of morbid obesity in both adults and adolescents co-morbidities of obesity such as glucose intolerance, type 2 diabetes (T2DM), metabolic syndrome, steatohepatitis, hyperlipidemia and cardiovascular disease. These co-morbidities of obesity have significant impacts on the overall quality of life of the individual and our society at large. Roux-en-Y gastric bypass (RYGB) and the relatively newer procedures of gastric banding (GB) and vertical sleeve gastrectomy (VSG) have proven to be efficacious in achieving rapid weight loss and reversing the comorbidities of obesity. Unfortunately, bariatric procedures are not without risks including micronutrient deficiency, failure to maintain lost weight, and mortality. Further, the resolution of T2DM has long been understood to precede weight loss, and this finding provides important clues about the physiologic underpinnings of the ...
This study is a contribution to the growing body of work on the influence of changes in the composition of an acrylic bone cement on various properties of the curing and cured material. The focus is on one commercially-available acrylic bone cement brand, Surgical Simplex P, and three variants of it and a series of properties, namely, setting time, maximum exotherm temperature, activation energy and frequency factor for the polymerization reaction, diffusion coefficient for the uptake of phosphate buffered saline, at 37 degrees C, ultimate compressive strength (UCS), plane-strain fracture toughness, fatigue life (under fully-reversed tension-compression stress), hardness (H) and elastic modulus (both determined using quasi-static nanoindentation), and the variation of the storage and loss moduli with frequency of the applied force in a dynamic nanoindentation test. It was found that (a) a 68% reduction in the volume of the activator, N,N dimethyl-4-toluidine, ...
Among the membrane filtration techniques, continuous cross-flow ultrafiltration (UF) is an innovative method to separate solid/liquid or liquid/liquid phases at a lower pressure of 5--150 psi compared to reverse osmosis (RO) in which the applied pressure is an order of magnitude higher. Recently, attempts have been made to combine processes of UF and other treatments for many applications. However, there is very little knowledge about the filtration process which combined coagulation and UF, and very few attempts have been made to apply coagulated UF to the treatment of fuel oil contaminated water. During the UF treatment of organic contaminants rapid declines in flux will occur due to the membrane fouling. Oil as a foulant plants an important role in the flux decrease. However, there are very limited pretreatment processes which can effectively remove fuel oil from water and hence solve the fouling problem. The purpose of the study was to examine the effectiveness ...
Full text: DNA rearrangement events leading to chromosomal aberrations are central to ionizing radiation-induced cell death. Although DNA double-strand breaks are probably the lesion that initiates formation of chromosomal aberrations, little is understood about the molecular mechanisms that generate and modulate DNA rearrangement. Examination of the sequences that flank sites of DNA rearrangement may provide information regarding the processes and enzymes involved in rearrangement events. Accordingly, we developed a method using inverse PCR that allows the detection and sequencing of putative radiation-induced DNA rearrangements in defined regions of the human genome. The method can detect single copies of a rearrangement event that has occurred in a particular region of the genome and, therefore, DNA rearrangement detection does not require survival and continued multiplication of the affected cell. Ionizing radiation-induced DNA rearrangements were detected in ...
To evaluate the role of phytochelatins and metallothioneins in heavy metal tolerance of black mangrove Avicennia germinans, 3-month-old seedlings were exposed to cadmium or copper for 30 h, under hydroponic conditions. Degenerate Mt2 and PCS primers were synthesized based on amino acid and nucleotide alignment sequences reported for Mt2 and PCS in other plant species found in GenBank. Total RNA was isolated from A. germinans leaves and two partial fragments of metallothionein and phytochelatin synthase genes were isolated. Gene expression was evaluated with reverse transcripatase-polymerase chain reaction (RT-PCR) amplification technique. Temporal analysis showed that low Cd{sup 2+} and Cu{sup 2+} concentrations caused a slight (but not significant) increase in AvMt2 expression after a 16 h exposure time, while AvPCS expression showed a significant increase under the same conditions but only after 4 h. Results strongly suggest that the rapid increase in AvPCS ...
To evaluate the role of phytochelatins and metallothioneins in heavy metal tolerance of black mangrove Avicennia germinans, 3-month-old seedlings were exposed to cadmium or copper for 30 h, under hydroponic conditions. Degenerate Mt2 and PCS primers were synthesized based on amino acid and nucleotide alignment sequences reported for Mt2 and PCS in other plant species found in GenBank. Total RNA was isolated from A. germinans leaves and two partial fragments of metallothionein and phytochelatin synthase genes were isolated. Gene expression was evaluated with reverse transcripatase-polymerase chain reaction (RT-PCR) amplification technique. Temporal analysis showed that low Cd"2"+ and Cu"2"+ concentrations caused a slight (but not significant) increase in AvMt2 expression after a 16 h exposure time, while AvPCS expression showed a significant increase under the same conditions but only after 4 h. Results strongly suggest that the rapid increase in AvPCS expression ...
The aim of this work was to compare the electrochemical behaviors and safety performance of graphite and the lithium titanate spinel Li1.33Ti1.67O4 with half-cells versus Li metal. Their electrochemical properties in 1 M LiPF6/EC + DEC (1:1 w/w) or 1 M LiPF6/PC + DEC (1:1 w/w) at room and elevated temperatures (30 and 60 deg C) have been studied using galvanostatic cycling. At 30 deg C graphite has higher reversible capacity than Li1.33Ti1.67O4 when using the LiPF6/EC + DEC as electrolyte. At 60 deg C graphite declines in cell capacity yet Li1.33Ti1.67O4 remains almost unchanged. In a propylene carbonate (PC) containing electrolyte, graphite electrode exfoliates and loses its mechanical integrity while Li1.33Ti1.67O4 electrode is very stable. An accelerating rate calorimeter (ARC) and microcalorimeter have been used to compare the thermal stability of lithiated lithium titanate spinel and graphite. Results show that Li1.33Ti1.67O4 may be used ...
The adequacy of the nasopharyngeal airway has been found to be related to craniofacial development. Obstruction of the airway by adenoid tissue, nasal septal deviation or abnormal morphology of the area is associated with characteristic changes in craniofacial morphology such as long anterior face height, facial retrognathism, and a steep inclination of mandibular plane often with a high vaulted palate and crossbite. Some studies have shown the changes to be reversible after adenoidectomy which improves nasal airway patency and a control mechanism for facial growth has been proposed to account for the relationships between airway adequacy, craniofacial morphology and craniocervical postural relationships. It is therefore important to be able to measure nasal respiratory resistance so that the effect of operative procedures in the area such as rapid maxillary expansion (RME) can be determined. Nasal respiratory resistance (NRR) is a measure of ...
Density functional theory (DFT) calculations using plane-wave methods were performed for Li2TMPO4F, LiTMPO4F, and TMPO4F (TM=V, Mn, Fe, Co, Ni) to address their feasibility as high-voltage cathode materials for Li ion batteries. We computed their structures, average open circuit voltages, and thermal stabilities for step-wise lithiation/delithation (discharge/charge) reactions. The calculations suggest that associated unit cell volume changes are sufficiently small on average that they should not be a significant detriment to the mechanical stability of the cathode. In the nickel case, the calculated volume change deviates from the series by increasing during the first delithiation step. Furthermore, the volume increases for all these materials during the second delithiation step. It appears that the relative volume expansion in the series during delithiation is directly correlated to the degree of d-p rehybridization. Predicted average open circuit voltages ...
Scanning ion microscopy with polarization analysis (SIMPA) is used to study the spin-resolved surface magnetic structure of nano-sized magnetic systems. SIMPA is utilized for in situ topographic and spin-resolved magnetic domain imaging as well as for focused ion beam (FIB) etching of desired structures in magnetic or non-magnetic systems. Ultra-thin Co films are deposited on surfaces of Si(1 0 0) substrates, and ultra-thin, tri-layered, bct Fe(1 0 0)/Mn/bct Fe(1 0 0) wedged magnetic structures are deposited on fcc Pd(1 0 0) substrates. SIMPA experiments clearly show that ion-induced electrons emitted from magnetic surfaces exhibit non-zero electron spin polarization (ESP), whereas electrons emitted from non-magnetic surfaces such as Si and Pd exhibit zero ESP, which can be used to calibrate sputtering rates in situ. We ...
A number of interactions between magnetic fields and matter is reviewed. The resulting forces range in magnitude from the very large, obtained in high-energy fields, to the weak ones caused by the magnetostriction of ferromagnets. The fundamentals of these interactions are highlighted, and the examples discussed are forces on dipoles, particle alignment, magnetostrictive forces, magnetic forming, magnetic stirring, levitation melting, and magnetic pulsing of tool steels. (orig.)
A model is available in predicting flocculation frequencies between particles of various properties under the influence of a magnetic field. This model provides a basic understanding of fundamental phenomena, such as particle-particle and particle-collector interactions, occurring in HGMF (high gradient magnetic field), and will be extended to describe experimental data of particle flocculation and filtration and predict the performance of high- gradient magnetic filters. It is also expected that this model will eventually lead to a tool for design and optimization of magnetic filters for environmental, metallurgical, biochemical, and other applications.
An efficient method of hydrogen storage in nano-porous carbons is its reversible sorption by electrochemical decomposition of a KOH water solution according to the following equation: C + xH{sub 2}O + xe{sup -} {yields} (CH{sub x}) + xOH{sup -} where (CH{sub x}) stands for the hydrogen inserted into the nano-porous carbon during charging and oxidized during discharging. Although various carbon materials have been investigated as hydrogen adsorbents, the information about the storage mechanism as well as the nature of the hydrogen/carbon interaction is still not sufficient. In order to extend the understanding of the process, carbon samples charged electrochemically were investigated by temperature programmed desorption (TPD). The nature of the hydrogen/carbon interaction was studied by electrochemical analysis at different temperatures. The TPD experiments consist of heating the samples from room temperature to 950 C and of quantitative ...
Three phosphate based ceramics were studied for the immobilization of tri- and tetravalent actinides: britholites Ca{sub 9}Nd{sub 1-x}An{sub x} {sup IV}(PO{sub 4}){sub 5-x}(SiO{sub 4}){sub 1+x}F{sub 2}, monazites/brabantites Ln{sub 1-2x}{sup III}Ca{sub x}An{sub x}{sup IV}PO{sub 4} and Thorium Phosphate Diphosphate (TPD) Th{sub 4-x}An{sub x}{sup IV}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}. For each material, the incorporation of Th, U(IV), or Ce(IV) in the structure was examined. This work was the early beginning of the incorporation of {sup 239}Pu and/or {sup 238}Pu in order to evaluate the effects of {alpha} -decay on these three crystallographic structures. The syntheses were carried out using dry chemistry methods, involving mechanical grinding then heating treatment (1100 deg C {<=} {theta} {<=} 1400 deg C). For britholites, we showed that the incorporation of thorium was complete for weight loading lower than 20 wt.% through the (Nd{sup 3+}, PO{sub ...
The reverse approach to critical (RAC) experiments were performed in the ZPR-IX critical facility at Argonne National Laboratory. One of the major objectives of this project is to determine the adequacy of the low-level flux monitor (LLFM) detectors for initial loading of the Fast Flux Test Facility (FFTF). 5 references. (auth)
AOT reverse micelles are used to cosolubilize hydrophilic and hydrophobic reactants of lipase catalysed esterification. Depending on the nature of the alcohol, a drastic change of the initial rate of the esterification is observed. A structural study of the micellar system with and without reactant is undertaken to explain the change in the activity with the various alcohols. PMID:7832997
This paper examines the seismic signatures of discrete, finite-length fractures, and outlines an approach for elastic, prestack reverse-time imaging of discrete fractures. The results of this study highlight the importance of incorporating fracture-generated P-S converted waves into the imaging method, and presents an alternate imaging condition that can be used in elastic reverse-time imaging when a direct wave is recorded (e.g., for crosswell and VSP acquisition geometries).
The endogenous reverse transcriptase reaction of equine infectious anemia virus (EIAV) has been studied, and conditions allowing synthesis of full-length minus-strand DNA have been determined. In contrast...Full Text Available
The Gordon Research Conference (GRC) on 2004 Gordon Research Conference on Reversible Associations in Structure & Molecular Biology was held at Four Points Sheraton, CA, 1/25-30/2004. The Conference was well attended with 82 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students.
Most pumped-storage plants have the capability to operate as synchronous condensers. As such, they can be brought on line very quickly to support system load requirements. However, one of the effects of making a rapid transition from synchronous condenser operation to turbine/governor operation is an initial reverse power flow into the machine. This reverse power flow can be very undesirable at a time when the system is calling for load support. On weak or isolated systems, this reverse power flow can lead to objectionable voltage and frequency dips in the system. With the proper utilization of a static frequency converter (SFC) and its associated controls and auxiliary switchgear systems, the reverse power flow resulting from a transition from synchronous condenser operation can be eliminated. This paper will describe the method by which an SFC system can be used to make this rapid load response in ...
Abstract in english We present a detailed derivation of the effective dielectric constant to be used in the dispersion relation for electrostatic waves in the case of a plasma immersed in a inhomogeneous magnetic field, with inhomogeneity perpendicular to the direction of the magnetic field.
A tutorial account is given of the main characteristics and distinctive features of conceptual magnetic fusion systems employing the magnetic mirror principle. These features are related to the potential advantages that mirror-based fusion systems may exhibit for the generation of economic fusion power.
An analytic model of magnetic torques applied to an accreting neutron star is employed to evaluate the magnetic dipole moments of x-ray pulsars. A new type of close binary system containing a neutron star is suggested.
An introduction to time-of-flight neutron spectroscopy is presented in the context of the study of magnetic materials. Examples are taken from the class of rare earth and actinide magnetic materials known as `strongly correlated electron` systems. (author) 11 figs., 24 refs.
The past decade has seen the development of eddy current probes for inspection of the mildly ferro-magnetic alloy Monel 400. Due to the rapid advances in permanent magnet technology similar probes have been upgraded to magnetically saturate, and hence ins...
The disclosure is directed to an active magnetic regenerator apparatus and method. Brayton, Stirling, Ericsson, and Carnot cycles and the like may be utilized in an active magnetic regenerator to provide efficient refrigeration over relatively large temperature ranges.
Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (#approx# 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)
Principle advantages of magnetic forming for part manufacture appear to lie ... to be an area of great potential for the magnetic forming process. We have a ...
OBJECTIVE--The study was performed to examine the influence of the exposure to magnetic fields in the potrooms of an electrolysis plant on the occurrence of musculoskeletal symptoms among the employees....Full Text Available
Several refrigerators for liquid helium and liquid nitrogen systems have been integrated successfully into IGC manufactured whole body Magnetic Resonance Imaging (MRI) magnet systems. The refrigerators have been tested in systems with magnetic fields of 0.6T to 1.5T. Tests were performed to study the effectiveness of the refrigerators, the magnetic field effects on the refrigerators, the effect of the refrigerators on the field uniformity and magnetic resonance image quality. The interface between the refrigerator and the whole body MRI magnet system cryostat was specifically designed to allow retrofit to the existing IGC magnet systems, while ensuring good heat transfer characteristics and good vibration isolation from the cryostat. The interface between the refrigerator and the cryostat and the refrigerator test results are presented.
The Muon Ionization Cooling Experiment (MICE) focusing solenoid magnets focus the muon beam within the MICE cooling channel on a liquid or solid absorber that is within the warm bore of solenoid. The focusing magnet has a warm bore of 470 mm. his magnet consists of two coils 210-mm long that is separated by an aluminum mandrel that is 200 mm long. Each of the coils has its own leads. The coils may be operated in either the non-flip mode (solenoid mode with both coils at the same polarity) or the lip mode (quadrupole focusing mode where both coils are at opposite polarity). This report describes the focusing solenoid magnet design that will be built by the vendor. The progress on the construction of the first of the focusing magnets will also be discussed in this report. Ultimately three of these magnets will be built. These magnets will be ...
The ternary rare earth compound NdRh_4B_4 has been studied by means of critical field, low temperature heat capacity, and static magnetic susceptibility measurements. Features in the upper critical field and heat capacity data at 1.31 K and 0.89 K suggest the occurrence of long-range magnetic order in the superconducting state. The temperature dependence of the static magnetic susceptibility follows a Curie-Weiss law with an effective magnetic moment #mu#sub(eff) = 3.58 +- 0.05 #mu#sub(B) and a Curie-Weiss temperature thetasub(p) = -6.2 +- 1.0 K between 20 K and room temperature. However, magnetization vs. applied magnetic field isotherms suggest the development of a ferromagnetic component in the Nd"3"+ magnetization at low temperatures. (author).
Highly ordered arrays of Ni nanoholes and Fe{sub 20}Ni{sub 80} antidots have been prepared, respectively, by replica/antireplica processing and sputtering techniques using nanoporous alumina membranes as templates. Geometrical characteristics as nanohole/antidot diameter, interpore distance and the overall hexagonal symmetry of arrays are controlled through the original templates. Experimental data on their hysteresis and magnetic domain structure have been taken by vibrating sample magnetometry and magnetic force microscopy, respectively. An analysis of the magnetization process, resulting magnetic anisotropy and magnetic domain structure is summarized considering the influence of those geometry aspects. In particular, the hexagonal symmetry and the density of nanohole/antidots determine the overall magnetic behavior, which is of interest in future high-density ...
Highly ordered arrays of Ni nanoholes and Fe20Ni80 antidots have been prepared, respectively, by replica/antireplica processing and sputtering techniques using nanoporous alumina membranes as templates. Geometrical characteristics as nanohole/antidot diameter, interpore distance and the overall hexagonal symmetry of arrays are controlled through the original templates. Experimental data on their hysteresis and magnetic domain structure have been taken by vibrating sample magnetometry and magnetic force microscopy, respectively. An analysis of the magnetization process, resulting magnetic anisotropy and magnetic domain structure is summarized considering the influence of those geometry aspects. In particular, the hexagonal symmetry and the density of nanohole/antidots determine the overall magnetic behavior, which is of interest in future high-density ...
... M(TH) in applied magnetic fields up to ± 7 T and for temperatures ranging from 2 to 300 K. The superparamagnetic (SPM) behavior of these metallic ...
Effective localization of small magnets against a noisy, real world background can involve various methods to first identify the magnetic fields produced by the magnet of interest, then to filter out background noise, and then to analyze the available magnetic field data to localize the magnet. Here we discuss low cost techniques which allow localization of small magnets with field strengths in the milliGauss range against real world background fields in the range of hundreds of mG, which may be fluctuating by up to tens of mG. Such techniques allow magnet tracking to be used to localize catheters in place of more invasive and expensive methods, e.g. fluoroscopy, for a variety of applications, including drug infusion with peripherally inserted central catheters (PICCs), laser ablation (TMR, PTMR) and introduction of pacemaker leads.
Development of Portable Normobaric Hypoxia and Pulsed Magnetic Field Firmware System for Enhancement of Radio- and Non-specific Resistance in Workers of Environmentally Hazardous Industries
The dynamic response of cylindrical and ring-shaped YBaCuO bulk parts to pulsed magnetic fields is calculated by using small sets of finite elements. Some comparisons with experimental results are provided, and they give confidence in the modelling of the superconducting properties. Transient magnetizations as a function of time and space as well as shapes and absolute values of trapped magnetic flux profiles are presented. The influence of the sample geometry is investigated for different millisecond pulsed magnetization processes. Results are reported for different radial thicknesses and heights, different pulse durations, peak magnetic fields and pulse sequences with and without stepwise cooling. Comparisons concerning the achievable trapped magnetic field and flux are made, and implications for the use of high-temperature superconductor bulk parts as ...
A nanosuspension of magnetically tagged metronidazole was developed by the solvent displacement method coupled with ultrasonication and was evaluated for its physicochemical properties. The drug release from metronidazole magnetic nanosuspension at pH 1.2 and 7.0 shows maximum correlation coefficient for zero order and Higuchi model, respectively. The anthelmintic activity of the formulated metronidazole magnetic nanosuspension was evaluated on Indian earthworms (Pheretima poi). Metronidazole magnetic nanosuspension at a dose of 10 and 50 mg/ml shortened by 31% and 34%, respectively, the mean time to death of the earthworms when compared against a non-magnetic metronidazole suspension. Thus, the developed metronidazole magnetic nanosuspension showed potent, controlled and targeted drug action and might be a good therapeutic avenue in combating infectious GI ...
With the increased costs of maintaining boilers and chillers entrepreneurs around the country have offered magnetic and similar devices to facilities as viable alternatives to their maintenance program. This report gives a brief history of some of the pre...
... design, and manufacturing knowledge have been acquired and used to develop an 'in-house' capability for the fabrication of magnetic forming coils ...
has been generally related to magnetic forming. One of the methods suggested was the following: A "pancake" magnetic coil is placed over a thin aluminum ...
From optical point of view and due to the magnetic interaction of the cold neutrons with the unpaired electron shell, magnetic materials hae a neutron spin-dependent refractive index n[sup +] [spin up] and n[sup -] [spin down]. Magnetic media such as Fe, Co and Ni react like birefringent uniaxial crystals in ordinary optica. n[sup +] and n[sup -] are the equivalent of the ordinary and extraordinary refractive indices. The specular reflection of spin polarized neutrons which is due to the discontinuity of the magnetic induction at the surface of the ferromagnet is a sensitive probe of surface and interface magnetism. We shall first give the background of the art of polarized neutron optics. Secondly, some recent examples from surface and interface magnetism will be given to illustrate the power of this technique such as the magnetic coupling ...
For the purpose of solving the limitations such as shape and dimension for magnetic compact fabricated by conventional anisotropic forming under magnetic orienting field, the feasibility of a new magnetic forming process was studied. Ferrite powder mixed with UV resin was compacted in the die mold and followed by alignment under the magnetic field. Effects of viscosity of UV resin and forming condition on magnetic characteristics of the compact was investigated. Maximum degree of alignment for the ferrite powder reached to 0.826. It was predicted that the proposed method had make it possible to fabricate a high performance magnet having the anisotropic alignment of the magnetic powder. The UV resin is desirable to have low viscosity, good properties such as formability and configuration stability for the compact and also parting- ability ...
magnet research at several national laboratories through its Advanced Accelerator Technology Program. The HEP Conductor Development Program, a collaboration among national...
number of technical requirements and performance criteria can drive stellarator costs, e.g., tight tolerances, accurate coil positioning, low aspect ratio (compactness), choice of assembly strategy, metrology, and complexity of the stellarator coil geometry. With the completion of a seven-year design and construction effort of the National Compact Stellarator Experiment (NCSX) it is useful to interject the NCSX experience along with the collective experiences of the NCSX stellarator community to improving the stellarator configuration. Can improvements in maintenance be achieved by altering the stellarator magnet configuration with changes in the coil shape or with the combination of trim coils? Can a mechanical configuration be identified that incorporates a partial set of shaped fixed stellarator coils along with some removable coil set to enhance the overall machine maintenance? Are there other approaches that will simplify the concepts, ...
A number of technical requirements and performance criteria can drive stellarator costs, e.g., tight tolerances, accurate coil positioning, low aspect ratio (compactness), choice of assembly strategy, metrology, and complexity of the stellarator coil geometry. With the completion of a seven-year design and construction effort of the National Compact Stellarator Experiment (NCSX) it is useful to interject the NCSX experience along with the collective experiences of the NCSX stellarator community to improving the stellarator configuration. Can improvements in maintenance be achieved by altering the stellarator magnet configuration with changes in the coil shape or with the combination of trim coils? Can a mechanical configuration be identified that incorporates a partial set of shaped fixed stellarator coils along with some removable coil set to enhance the overall machine maintenance? Are there other approaches that will simplify the concepts, ...
CERN signed a Co-operation Agreement with the Government of Pakistan in 1994, which was followed in 1997 by a Protocol signed with the Pakistan Atomic Energy Commission (PAEC) concerning CMS magnet supports. CERN and PAEC then signed in 1998 a Memorandum of Understanding for collaboration in the construction of the CMS detector. The participation by Pakistani scientists and engineers in the CERN programme is channelled through the National Centre of Physics (NCP) established at the Quaid-i-Azzam University in Islamabad, under the terms of a 1999 Protocol to the 1994 Co-operation Agreement. The engineering and detector construction work performed under these Agreements has been of high quality, and the Pakistani participation is valued highly by the CMS collaboration. In continuation of this co-operation, Pakistan, represented by PAEC as funding agency, has now proposed to make in-kind contributions to the LHC Project, such as mechanical ...
Superconducting Cu-rich composites containing the A-15 compounds V_3Si or V_3Ga were made by the ''Tsuei'' process (melting into ingots followed by cold working and heat treatment). Superconducting transition temperatures of the composites were measured. X-ray diffraction analyses were performed. Microstructures were studied using both the optical metallograph and the scanning electron microscope. For some composites containing V_3Ga, the critical current densities as functions of transverse magnetic field up to 60 kG, and as functions of temperature from 4.2 to 12"0K were measured. It was found that the Tsuei process does not work for the composites containing V_3Si, but works satisfactorily for V_3Ga; reasons are discussed. Relations between measured properties and various metallurgical factors such as alloy compositions, cross-section reduction ratios, and heat treatment are discussed. The mechanism for the observed superconductivity in the ...
In an attempt to enhance the electrical and mechanical properties of the high temperature superconducting oxides, high T(sub c) composites were prepared composed of the 123 compounds and AgO. The presence of extra oxygen due to the decomposition of AgO at high temperature is found to stabilize the superconducting 123 phase. Ag is found to serve as clean flux for grain growth and precipitates as pinning center. Consequently, almost two orders of magnitude enhancement in critical current densities were also observed in these composites. In addition, these composites also show much improvement in workability and shape formation. On the other hand, proper oxygen treatment of Y5Ba6Cu11Oy was found to possibly stabilize superconducting phase with T(sub c) near 250 K. I-V, ac susceptibility, and electrical resistivity measurements indicate the existence of this ultra high T(sub c) phase in this compound. Detailed structure, microstructure, electrical, ...
Supermetal with critical characteristics is under advanced investigation for further improvement of metal materials. Although iron is most frequently used as structural material among various metals, it should be used more carefully and effectively because of resource limitation and global environmental problem. It is essential to draw various excellent properties much more from iron and to improve recyclability. In particular, the best way to meet these requirements is achievement of more fine structure and higher purity. Since the lowest crystalline grain size is now limited to nearly 10{mu}m, metallic structure composed of grains below 1{mu}m is expected by mesoscopic control. Various methods have been studied to achieve ultra-fine crystalline structure, and study of precise heat treatment control and ultra-strength metallurgy is required. Heat treatment in magnetic field and layered structure by mechanical alloying are also promising. ...
Functional imaging of the pharynx used to be the domain of cineradiography, CT and ultrafast CT. The development of modern MRI techniques led to new access to functional disorders of the pharynx. The aim of this study was to implement a new MRI technique to examine oropharyngeal obstructive mechanisms in patients with obstructive sleep apnea (OSA). Sixteen patients suffering from OSA and 6 healthy volunteers were examined on a 1.5 T whole-body imager ('Vision', Siemens, Erlangen Medical Engineering, Germany) using a circular polarized head coil. Imaging was performed with 2D flash sequences in midsagittal and axial planes. Patients and volunteers were asked to breathe normally through the nose and to simulate snoring and the Mueller maneuver during magnetic resonance imaging (MRI). Prior to MRI, all patients underwent an ear, nose and throat (ENT) examination, functional fiberoptic nasopharyngoscopy and polysomnography. A temporal resolution of ...
The present article outlines major features of the free electron laser (FEL) and reviews research and development of FEL. Relations among the oscillation frequency, electron beam parameters and wiggler parameters, the physical mechanism of amplification and the physical process of saturation are discussed to identify the difference between FEL and other lasers. The report also outlines techniques for accelerators which are used to generate high-quality, high-energy electron beams required for FEL experiments. Techniques to achieve a short wavelength, high output and high efficiency, and applications of FEL are also discussed. FEL consists of an electron accelerator, wiggler and optical resonator. In FEL, electron beams with a relativistic energy interact resonantly with an electromagnetic field to generate coherent electromagnetic waves. Unlike conventional lasers, FEL does not surfer from restrictions on its oscillation frequency associated with atomic, molecular ...
Epidemiologic studies suggest a weak link between occupational or residential exposure to extremely low frequency electromagnetic fields and cancer, especially tumors of the central nervous and hematopoietic systems. This report discusses these studies with reference to basic research on ELF EMF bioeffects relevant to cancer-promoting mechanisms. Many of the studies suggest a possible interaction of ELF EMF with the immune system, endocrine system, or growth-regulatory signals and morphogenic movements that involve calcium flux through cell membranes. Many bioeffects have been reported only with certain specific combinations of frequency, amplitude, and orientation of the EMF signal with respect to the geomagnetic field. The possibility of signal-specific effects raises a complication in dosimetry for both epidemiologic and experimental studies since ELF EMF effects may not be directly related to field strength. The report concludes with a discussion of design ...
The effect of the external pH on the intracellular pH in mung bean (Vigna mungo (L.) Hepper) root-tip cells was investigated with the "3"1P nuclear magnetic resonance (NMR) method. The "3"1P NMR spectra showed three peaks caused by cytoplasmic G-6-P, cytoplasmic Psub(i) and vacuolar Psub(i). The cytoplasmic and vacuolar pHs could be determined by comparing the Psub(i) chemical shifts with the titration curve. When the external pH was changed over a range from pH 3 to 10, the cytoplasmic pH showed smaller changes than the vacuolar pH, suggesting that the former is regulated more strictly than the latter. The H"+-ATPase inhibitor, DCCD, caused the breakdown of the mechanism that regulates the intracellular pH. H"+-ATPase appears to have an important part in the regulation of the intracellular pH. (author).
The downstream failure of cable during winding, insulating, coil winding, and coil assembly is a significant issue in magnet production. The impact of these failures are costly both financially, and from the time to recover from this downstream failure. The current approach to cabling has been to visually inspect the cable for any gross defects during cabling. To date this has been effective in finding small defects such as crossovers for example, which drastically reduce the mechanical integrity of the strand, and thus the cable itself. But because of the large volume of cable which will be manufactured an automated flaw detection system which can inspect the cable and detect these type of defects will be needed. We have recently done an on-line experiment using an Eddy current system, and specialized Eddy current probes to inspect cable during manufacturing. We will present the results of our inspection demonstrating detection of crossovers, ...
The downstream failure of cable during winding, insulating, coil winding, and coil assembly is a significant issue in magnet production. The impact of these failures is costly both financially and because of the time needed to recover from them. The current approach to cabling has been to visually inspect the cable for any gross defects during cabling. To date this has been effective in finding small defects such as crossovers, which drastically reduce the mechanical integrity of the strand and thus of the cable itself. But because of the large volume of cable that will be manufactured, an automated flaw detection system that can inspect the cable and detect these types of defects will be needed. We have recently done an on-line experiment using an Eddy current system and specialized Eddy current probes to inspect cable during manufacturing. We will present the results of our inspection, demonstrating detection of crossovers and cold welds. ...
The current status of the ZTH vacuum liner design is covered by this report. ZTH will be the first experiment to be installed in the CPRF (Confinement Physics Research Facility) at the Los Alamos National Laboratory and is scheduled to be operational at the rated current of 4 MA in 1992. The vacuum vessel has a 2.4 m major radius and a 40 cm minor radius. Operating parameters which drive the vacuum vessel mechanical design include a 300 C bakeout temperature, an armour support system capable of withstanding 25 kV, a high toroidal resistance, 1250 kPa magnetic loading, a 10 minute cycle time, and high positional accuracy with respect to the conducting shell. The vacuum vessel design features which satisfy the operating parameters are defined. The liner is constructed of Inconel 625 and has a geometry which alternates sections of thin walled bellows with rigid ribs. These composite sections span between pairs of the 16 diagnostic stations to ...
M-type hexagonal ferrite composition, Ba(1-x)SrxFe12O19 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), was prepared by a two route ceramic method. Complex permittivity (?'-j?'') and complex permeability (?'-j?'') have been measured using a network analyzer from 8.2 to 12.4 GHz X-ray diffraction confirmed the M-type hexagonal structure and a scanned electron micrograph was used to analyze the grain size distribution of ferrite. Substitution of Sr2+ ions causes an increase in porosity that deteriorates the electromagnetic and microstructural properties in the doped samples. Both dielectric constant and dielectric loss are enhanced in comparison to the permeability and magnetic loss over the entire frequency region. This is due to a resistivity variation and the formation of Fe2+ ions, which increases the hopping mechanism between Fe2+ and Fe3+ ions.
Beams may be viewed as directed and focussed flow of energy and information, carried by particles and electromagnetic radiation fields (ie, photons). Often, they interact with each other (eg, in high energy colliders) or with other forms of matter (eg, in fixed targets, sychrotron radiation, neutron scattering, laser chemistry/physics, medical therapy, etc.). The whole art and science of beams revolve around the fundamental quest for, and ultimate implementation of, mechanisms of production, storage, control and observation of beams -- always directed towards studies of the basic structures and processes of the natural world and various practical applications. Tremendous progress has been made in all aspects of beam physics and technology in the last decades -- nonlinear dynamics, superconducting magnets and rf cavities, beam instrumentation and control, novel concepts and collider praradigms, to name a few. We illustrate this progress with a ...
Many mechanical parts are subjected to stresses and strains that may eventually lead to their failure. In order to prevent the costly delays associated with equipment down-time, many parts have to be tested for weaknesses and defects when machinery is constructed or dismantled for maintenance. These procedures are known as Non-Destructive Testing (NDT) methods. Five types of non-destructive testing methods routinely used are radiographic testing, ultrasonic testing, magnetic particle inspection, liquid penetrant testing and eddy current testing. Out of these five techniques industrial radiography plays an important role in non-destructive testing to reveal interior defects in materials. In radiography almost two-thirds of the radiation reaching the film is scattered radiation which does not form the image of defects. Scattered radiation generated inside and outside a material has a very large effect on sensitivity of flaw detection since it ...
There has been a good deal of interest in the sialon system of ceramics in recent years due to their combination of important engineering properties #beta# including strength, hardness, low thermal expansion and good thermal shock resistance. #beta#-sialon (Si_6_-_zAl_zO_zN_8_-_z ;0mechanisms of formation of #beta#-sialon via the carbothermal reduction route and reports specifically on the utilisation of "2"9Si and "2"7Al solid state Nuclear Magnetic Resonance techniques in determining the nature of intermediate phases which occur. 9 refs., 1 tab., 1 fig.
The nanocrystallization process of amorphous Fe_7_3_._5Si_1_3_._5B_9Nb_3Cu_1 was investigated by active screen plasma nitriding (ASPN) treatment at temperatures ranging from 410 "oC to 560 "oC for 3 h in two gas mixtures of 75% N_2-25% H_2 and 25% N_2-75% H_2 at 5 mbar atmosphere. The amorphous ribbons were then annealed under vacuum at the same time and temperatures mentioned above. The structure of the samples was analyzed using various techniques such as X-ray diffraction (XRD), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). Microhardness measurements, electrical resistivity and Vibrating Sample Magnetometer (VSM) were used to study mechanical, electrical and magnetic properties of the samples, respectively. It was observed that the ASPN treatment leads to finer grain size and higher crystalline volume fraction and modifies the structural features of Fe(Si) phase. The Fe(Si) lattice parameter for the nitrided ...
The Self Actuated Shutdown System (SASS) is now under development for use in a large scale FBR, in order to establish the passive shutdown capability against the postulated ATWS events, i.e. ULOF, UTOP and ULOHS. The function of SASS makes use of the safety characteristics of a liquid metal cooled FBRs such as a large subcooling and low pressure system. The insertion of the control rods insertion is assured even in the most conservative seismic design condition by employing articulate rods and the SASS will be installed into the detaching mechanism employing a curie point the magnet alloy. ULOF analysis of the present FBR shows that coolant boiling inception is prevented if a control rod of the SASS is detached at the uppermost temperature of 680degC for the Curie point magnet, and after the reactor shutdown the coolant temperature is kept below 600degC by the pony motor flow. Therefore the SASS will establish passive ...
The magnetic properties of a single crystal of SmNiSn with the orthorhombic {epsilon}-TiNiSi-type crystal structure have been investigated by magnetic susceptibility, magnetization and electrical resistivity measurements from 1.5 K to room temperature. Two anomalies have been found in the magnetic susceptibility, indicating an antiferromagnetic phase transition at T{sub N}=9.4 K and a second transition at 4.4 K. A large magnetic anisotropy has been found at low temperatures in the temperature and field dependencies of magnetic susceptibility and magnetization. Below 80 K, the easy axis of the magnetization is the c-axis. At T=2.0 K, the c-axis magnetization curve exhibits metamagnetic-like behavior at H{sub c}=42 kOe and reaches 0.54 emu/g at H=55 kOe, whereas for the a- and b-axis the ...
A study on development of magnetic drive packless valves for commercial purpose showed the results as follows; 1. Study on the radial rays effecting to the permanent magnets -Measurement of the strength of Nd-magnets according to irradiation of radial rays. 2. Effects of temperature on the magnetic driving device -Temperature dependency of the Nd-casting magnets. -Effects of temperature on the heat releasing fins of high-temperature valve. 3. Optimization of torque -Arranging method of permanent magnets -Measuring method and results of torque. 4. Design, manufacture and test for the pressure-resisting structure of magnetic power transmitting device -Calculation and design for the flat circular plates under pressure of the magnetic power transmitting device -Design, manufacture and test for the pressure-resisting ...
180 deg magnet chamber is used in Folded Tandem Ion Accelerator for passage and 180 deg bending of ion beam. The chamber is placed between 180 deg terminal magnet (Electro-magnet), which is used for bending, and analysing the beams. Magnet with a particular magnetic field strength bends ions of only specified mass energy product through a precise path. There is also a space limitation in the direction of magnetic field. Both of them require the magnet chamber to be of a close tolerance. Accuracy of center distance between inlet and outlet port of the magnet chamber has to be at par with the concentricity of high energy and low energy beam line. To achieve this we started the fabrication of magnet chamber by following two methods: a) Circular rolling and bending of rectangular tube for 180 deg sector ...
Tests have recently been performed at Fermilab in order to measure the energy losses due to eddy currents and iron and superconductor magnetization. These measurements were performed on six 1.5m long model magnets and eight 15m long full scale collider dipole magnets. AC losses were measured as a function of ramp rate using sawtooth ramps from 500, to 5000 Amps for both types of magnets, while bipolar studies were additionally performed on some of the short magnets. The measured magnet voltage and current for a complete cycle are digitally integrated to yield the energy loss per cycle. Measurement reproducibility is typically 5%, with good agreement between long magnet measurements and extrapolations from short magnet measurement results. Magnetization loss measurements among similar ...
There is renewed interest in the development of natural gas vehicles in response to the challenge to reduce urban air pollution and consumption of petroleum. The natural gas/diesel dual fuel engine is one way to apply natural gas to the conventional diesel engine. Dual fuel engines operating on natural gas and diesel emit less nitrogen oxides, and less carbon soot to the air compared to conventional diesel engines. The problem is that at light loads, fuel efficiency is reduced and emissions of hydrocarbons and carbon monoxide are increased. This thesis focused on control methods for emissions of hydrocarbons and carbon monoxide in the dual fuel engine at light loads. This was done by developing a reverse flow catalytic converter to complement dual fuel engine exhaust characteristics. Experimental measurements and numerical simulations of reverse flow catalytic converters were conducted. Reverse flow creates a high reactor ...
An experimental and modelling study was performed for a reverse flow catalytic converter attached to a natural gas/diesel dual fuel engine. The catalytic converter had a segmented ceramic monolith honeycomb substrate and a catalytic washcoat containing a predominantly palladium catalyst. A one-dimensional single channel model was used to simulate the operation of the converter. The kinetics of the CO and methane oxidation followed first-order behaviour. The activation energy for the oxidation of methane showed a change with temperature, dropping from a value of 129 to 35 kJ/mol at a temperature of 874 K. The reverse flow converter was able to achieve high reactor temperature under conditions of low inlet gas temperature, provided that the initial reactor temperature was sufficiently high. (author)
A time-reversal-violating spin-correlation coefficient in the total cross section for polarized neutrons incident on a tensor rank-2 polarized target is calculated by assuming a time-reversal-noninvariant, parity-conserving ``five-fold" interaction in the neutron-nucleus optical potential. Results are presented for the system $n + {^{165}{\\rm Ho}}$ for neutron incident energies covering the range 1--20 MeV. From existing experimental bounds, a strength of $2 \\pm 10$ keV is deduced for the real and imaginary parts of the five-fold term, which implies an upper bound of order $10^{-4}$ on the relative $T$-odd strength when compared to the central real optical potential.
The development of calcium sulfate dihydrate (gypsum) mineral scale in reverse osmosis (RO) membrane desalting was investigated by direct real-time observation of crystal growth. Gypsum scaling studies were conducted in a specially modified plate-and-frame reverse osmosis cell fitted with an optical window, with dark-field membrane lighting arrangement within the membrane cell to enhance crystal boundaries and allow recording of digital surface images magnified through an optical microscope. The evolution of the surface number density (SND) of gypsum crystals resembled a sigmoidal population growth process with an increasing rate of crystal formation at higher solution supersaturation (with respect to gypsum) at the membrane surface. The rate of formation of new crystals declined as the su...
We propose a combined migration velocity analysis and imaging method based on Kirchhoff integral migration and reverse time migration, using the residual curvature analysis and layer stripping strategy to build the velocity model. This method improves the image resolution of Kirchhoff integral migration and reduces the computations of the reverse time migration. It combines the advantages of efficiency and accuracy of the two migration methods. Its application in tunnel seismic prediction shows good results. Numerical experiments show that the imaging results of reverse time migration are better than the imaging results of Kirchhoff integral migration in many aspects of tunnel prediction. Field data show that this method has efficient computations and can establish a reasonable velocity model and a high quality imaging section. Combination with geological information can make an accurate prediction of the front of the ...
Three different magnetic regimes; aerial, surface and buried; each with three different forces, have been used to investigate their effects on the water contents and photosynthetic pigments of sweet basil plants (Ocimum basilicum L.). Two groups of sweet basil seeds, Ocimum basilicum L. have been cultivated, one under normal conditions and the second has been subdivided into three portion (aerial, surface and buried) to examine the effect of different magnetic forces coming from the three directions on the resulted plants. At all directions of magnets, water contents have been significantly affected by the magnetic forces. Chlorophyll A and carotene contents have been affected, as well, according to the three magnetic forces coming from soil surface regime only. Chlorophyll B did not significantly affected by differences magnetic forces in the three regimes, but ...
The effects of a moderate-intensity static magnetic field (SMF) on osteoporosis of the lumbar vertebrae were studied in ovariectomized rats. A small disc magnet (maximum magnetic flux density 180 mT)...Full Text Available
Using the full potential linearized augmented plane wave (FLAPW) method, thickness dependent magnetic anisotropy of ultrathin FeCo alloy films in the range of 1 monolayer (ML) to 5 ML coverage on Pd(0 0 1) surface has been explored. We have found that the FeCo alloy films have close to half metallic state and well-known surface enhancement in thin film magnetism is observed in Fe atom, whereas the Co has rather stable magnetic moment. However, the largest magnetic moment in Fe and Co is found at 1 ML thickness. Interestingly, it has been observed that the interface magnetic moments of Fe and Co are almost the same as those of surface elements. The similar trend exists in orbital magnetic moment. This indicates that the strong hybridization between interface FeCo alloy and Pd gives rise to the large magnetic moment. Theoretically calculated ...
In the present paper the progress of optimization of soft magnetic properties have been studied by applying different experimental techniques (magnetic measurements, electric measurements, X-ray analysis, and high-resolution electron microscopy observation). It has been shown that an increase in magnetic permeability after optimization annealing can be mainly attributed to annealing out of microvoids. (author)
Neutron scattering techniques have been used to measure the static structure and magnetic excitations in amorphous magnets. Sum rules and computer models are used to discuss the relationship between the static disorder and the shape of the excitation spectrum. Polarized beam measurements of chi''(Q,E) are compared to analytical theories and computer calculations for the magnetic excitations in amorphous ferromagnets.
The MOS-technology allows to make tiny electronic lenses for multibeam electron systems. In the paper results of research and principles of designing of tiny magnetic electron lenses are submitted. Electronic lenses with a nonconventional configuration of tiny magnetic circuit and electronic lenses with coincident electric and magnetic fields in nonconventional tiny performance are considered
The influence of rigid-body and differential rotation and of a fine-scale chaotic magnetic field and a poloidal magnetic field on the minimum mass of a main-sequence star is investigated. It is shown that rotation and a magnetic field with an energy equal to 10--20% of the star's gravitational energy increase the minimum mass of a main-sequence star by 1.5--2 times.
Helical dipole magnets are required in a project for the Relativistic Heavy Ion Collider (RHIC) to control and preserve the beam polarization in order to allow the collision of polarized proton beams. Specifications are for low current superconducting magnets with a 100 mm coil aperture and a 4 Tesla field in which the field rotates 360 degrees over a distance of 2.4 meters. A magnet meeting the requirements has been developed that uses a small diameter cable wound into helical grooves machined into a thick-walled aluminum cylinder.
The Wendelstein 7-X (W7-X) modular stellarator is under construction at the Max-Planck-Institut fuer Plasmaphysik in Greifswald, Germany. The W7-X magnet system contains 70 coils made up from helium cooled superconducting cables in aluminium alloy (EN AW-6063) jackets. Several hundred connections of the jacket to the cable joints are made by aluminium-to-aluminium welds. Due to geometrical and thermal boundary conditions these welds cannot be accomplished free from defects. Microscopic analyses of the welds show that a variety of small flaws such as cracks and pores develop during welding. The welds have thus to be dimensioned accordingly, and appropriate weld qualification, investigation and testing has to be done in order not to jeopardise the structural integrity and leak tightness. The weld is mechanically loaded during cool-down due to the difference in thermal contractions between the GRP insulation and the aluminium, and during operation ...
The Wendelstein 7-X (W7-X) modular stellarator is under construction at the Max-Planck-Institut fuer Plasmaphysik in Greifswald, Germany. The W7-X magnet system contains 70 coils made up from helium cooled superconducting cables in aluminium alloy (EN AW-6063) jackets. Several hundred connections of the jacket to the cable joints are made by aluminium-to-aluminium welds. Due to geometrical and thermal boundary conditions these welds cannot be accomplished free from defects. Microscopic analyses of the welds show that a variety of small flaws such as cracks and pores develop during welding. The welds have thus to be dimensioned accordingly, and appropriate weld qualification, investigation and testing has to be done in order not to jeopardise the structural integrity and leak tightness. The weld is mechanically loaded during cool-down due to the difference in thermal contractions between the GRP insulation and the aluminium, and during operation ...
Two mechanical design requirements are defined for the SSC Collider beam tube. First, the vacuum requirement (luminosity lifetime = 150 hrs). It requires the design of a pressure boundary within the cold mass vessel to provide a vacuum tunnel for the proton beam and to minimize the synchrotron radiation gas desorbtion with a suitable material. The Collider beam tube design is under an intensive activity to search for a material that will meet the luminosity requirement without a distributed pump or liner. Second is the tube wall`s resistivity requirement ({sigma}*t = 2E5 {Omega}{sup {minus}1}). For a 4.2 K beam tube the Cu thickness is 100 {mu}m (RRR=30,6.7 T, {sigma}=2E9{Omega}{sup {minus}1}m{sup {minus}1}). The copper yield strength is relatively low in comparison to steel and, therefore, the design of the steel layer is governed by the copper layer yield stress limit. A beam tube subjected to eddy current load in a quenching dipole requires an optimum diameter ...
Two mechanical design requirements are defined for the SSC Collider beam tube. First, the vacuum requirement (luminosity lifetime = 150 hrs). It requires the design of a pressure boundary within the cold mass vessel to provide a vacuum tunnel for the proton beam and to minimize the synchrotron radiation gas desorbtion with a suitable material. The Collider beam tube design is under an intensive activity to search for a material that will meet the luminosity requirement without a distributed pump or liner. Second is the tube wall's resistivity requirement ([sigma]*t = 2E5 [Omega][sup [minus]1]). For a 4.2 K beam tube the Cu thickness is 100 [mu]m (RRR=30,6.7 T, [sigma]=2E9[Omega][sup [minus]1]m[sup [minus]1]). The copper yield strength is relatively low in comparison to steel and, therefore, the design of the steel layer is governed by the copper layer yield stress limit. A beam tube subjected to eddy current load in a quenching dipole requires an optimum ...
The compound GdPd{sub 2}Si, which is reported to order antiferromagnetically at 13 K, has been investigated by heat capacity and electrical resistivity measurement in the presence of external magnetic fields. In contrast to an earlier report, the zero-field heat capacity and resistivity data indicate two magnetic transitions at 13 and 17 K. The external magnetic field substantially influences the resistivity and heat capacity of the compound around the magnetic ordering temperature. The magnetocaloric effect, which is calculated from in-field heat capacity data, is quite large around the magnetic transition temperature. The magnetoresistance is also large near the magnetic ordering temperature. The metamagnetic transition is observed for 10 kOe magnetic field both in magnetocaloric and in magnetoresistance data. The metamagnetic transition ...
The compound GdPd_2Si, which is reported to order antiferromagnetically at 13 K, has been investigated by heat capacity and electrical resistivity measurement in the presence of external magnetic fields. In contrast to an earlier report, the zero-field heat capacity and resistivity data indicate two magnetic transitions at 13 and 17 K. The external magnetic field substantially influences the resistivity and heat capacity of the compound around the magnetic ordering temperature. The magnetocaloric effect, which is calculated from in-field heat capacity data, is quite large around the magnetic transition temperature. The magnetoresistance is also large near the magnetic ordering temperature. The metamagnetic transition is observed for 10 kOe magnetic field both in magnetocaloric and in magnetoresistance data. The metamagnetic transition ...
This paper reports that only a few years ago superconducting magnetic separation was viewed as the next major market for superconducting magnets. The first commercial units had been installed, worked flawlessly, and demonstrated real economic viability. The potential market was seen as quite large, and many people believed that superconducting magnetic separation would soon show the same rapid growth that MRI had demonstrated after its initial success. These hopes even prompted IGC, one of the top MRI magnet builders, to form a separate division devoted to magnetic separation. Despite the existence of Magstream, IGC has not been overly active in the market. As a technology that has applications from the clay on the Earth to the soil on the moon, superconducting magnetic separation has yet to become widely used.
The characteristics of the local magnetic shear, a quantity associated with high-mode-number ballooning mode stability, are considered in heliotron/torsatron devices that have a large Shafranov shift. The local magnetic shear is shown to vanish even in the stellarator-like region in which the global magnetic shear is positive. The reason for this is that the degree of the local compression of the poloidal magnetic field on the outer side of the torus, which maintains the toroidal force balance, is reduced in the stellarator-like region of global magnetic shear because the global rotational transform in heliotron/torsatron systems is a radially increasing function. This vanishing of the local magnetic shear is a universal property in heliotron/torsatron systems with a large Shafranov shift since it results from toroidal force balance in the stellarator-like ...
We have analyzed the MHD flow of a conducting couple stress fluid in a slit channel with rhythmically contracting walls. In this analysis we are taking into account the induced magnetic field. Analytical expressions for the stream function, the magnetic force function, the axial pressure gradient, the axial induced magnetic field and the distribution of the current density across the channel are obtained using long wavelength approximation. The results for the pressure rise, the frictional force per wave length, the axial induced magnetic field and distribution of the current density across the channel have been computed numerically and the results were studied for various values of the physical parameters of interest, such as the couple stress parameter ?, the Hartmann number M, the magnetic Reynolds number R and the time averaged mean flow rate ?. Contour plots for the stream and ...
This research deals with in the study of the use of innovating magnetic sensors in eddy current non destructive inspection. The author reports an analysis survey of magnetic sensor performances. This survey enables the selection of magnetic sensor technologies used in non destructive inspection. He presents the state-of-the-art of eddy current probes exploiting the qualities of innovating magnetic sensors, and describes the methods enabling the use of these magnetic sensors in non destructive testing. Two main applications of innovating magnetic sensors are identified: the detection of very small defects by means of magneto-resistive sensors, and the detection of deep defects by means of giant magneto-impedances. Based on the use of modelling, optimization, signal processing tools, probes are manufactured for these both applications.
We compare experimental data for temperature dependence of the magnetic order parameter and the magnetic excitations (spin waves) in materials with a quenched orbital moment and a well-defined spin quantum number. It is observed that the thermal decrease of the two quantities proceeds according to the same analytical function of the type y(T)=1-cT"#epsilon# with an identical exponent #epsilon#. This power function applies not only asymptotically for T->0 but holds over a wide temperature range. The exponent #epsilon# is universal, i.e. independent of spin order type and lattice symmetry and depends only on the dimensionality of the relevant interactions and on whether the spin quantum number is integer or half-integer. The different T"#epsilon# functions are identified as representations of stable universality classes. The fact that order parameter and magnetic excitations follow the same T"#epsilon# function shows that ...
In the framework of the search for a ceramic material usable in the radioactive waste storage, uranium and thorium phosphates have been investigated. Their experimental synthesis conditions have been entirely reviewed, they lead to the preparation of four new compounds: U(UO{sub 2})(PO{sub 4}){sub 2}, U{sub 2}O(PO{sub 4}){sub 2}, UCIPO{sub 4}, 4H{sub 2}O, and Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}. Experimental evidenced are advanced for non existent compounds such as: U{sub 3}(PO{sub 4}){sub 4}, U{sub 2}O{sub 3}P{sub 2}O{sub 7} and Th{sub 3} (PO{sub 4}){sub 4}. Characterization by several techniques (X-rays and neutron powder diffractions, UV-Visible and Infra-red spectroscopies, XPS,...) were performed. The ab initio structure determination of U(UO{sub 2})(PO{sub 4}){sub 2} has been achieved by X-rays and refined by neutron diffractions. Through its physico-chemical analysis, we found that this compound was a new mixed valence uranium phosphate in which U{sup 4+} and UO{sub ...
Chemical looping combustion (CLC) is a novel technology where CO{sub 2} is inherently separated during combustion. Due to the existence of sulfur contaminants in the fossil fuels, the gaseous products of sulfur species and the interaction of sulfur contaminants with oxygen carrier are a big concern in the CLC practice. The reactivity of NiO/Al{sub 2}O{sub 3} oxygen carrier reduction with a gas mixture of CO/H{sub 2} and H{sub 2}S is investigated by means of a thermogravimetric analyzer (TGA) and Fourier Transform Infrared spectrum analyzer in this study. An X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM) are used to evaluate the phase characterization of reacted oxygen carrier, and the formation mechanisms of the gaseous products of sulfur species are elucidated in the process of chemical looping combustion with a gaseous fuel containing hydrogen sulfide. The results show that the rate of NiO reduction with ...
We discuss how magnetic phenomena affect superconductivity in simple metals, transition metals and alloys thereof, and dilute Rare-Earth alloys. It is shown both qualitatively and quantitatively that superconductors are sensitive probes for studying itinerant spin excitations, local spin excitations associated with nearly magnetic impurities, the effect of the atomic environment on the stability of local magnetic moments, and the nature of the spin order in Rare-Earth alloys. Also, we discuss how magnetic impurities can be used to study the electronic configuration which is responsible for superconductivity in Laves-phase crystals like A-15 compounds and ..beta..-W crystals, for example.
The magnetization of ultrathin bcc Fe films (two and three monolayers) on MgO was measured and compared with the behavior predicted for a two-dimensional ferromagnet. The experiment indicated that no hysteresis was present in the magnetization. Instead, the magnetization at low temperature was affected by a marked field cooling effect. These observations lead to the conclusion that films of Fe on MgO of such thickness exhibit superparamagnetic behavior as if they were not entirely continuous. In contrast, films thicker than five monolayers exhibit a magnetic response close to that of bulk iron.
It has been carried out the magnetic properties determination for high iron oxide content glasses series obtained from a geothite red mud waste from the zinc hydrometallurgy and dolomite and glass cullet as main raw materials. It has been determined the magnetic susceptibility and magnetization values for the glasses here investigated. The results suggest that the magnetic behaviour are depending on the glass chemical composition, so that glasses can be differently classified like ferrimagnetic, ferromagnetic, superparamagnetic and paramagnetic. (Author) 6 refs.
Magnetic fluctuations present in the paramagnetic Mn{sub 0.81}Ni{sub 0.19} system have been investigated by measuring inelastic magnetic neutron scattering from a single crystal at temperatures of 450, 585 and 700 K. Antiferromagnetic correlations are observed to be present at all the temperatures studied. The spectral width of the magnetic scattering has been observed to increase with temperature, while the spatial range of the magnetic correlations is seen to decrease as the temperature is raised. The wave-vector-dependent susceptibility is found to follow a Curie-Weiss law near the (1 0 0) position, in agreement with theoretical predictions.
It is suggested that the magnetic Ap stars can be rotationally decelerated to long periods by the braking action of the associated magnetic field on time scales of order 10"7--10"1"0 years depending on whether the star's dipole field is aligned perpendicular or parallel to the rotation axis. Rotation includes a toroidal magnetic field in the plasma surrounding a star, and the accompanying magnetic stresses produce a net torque acting to despin the star. These results indicate that it is not necessary to postulate mass loss or mass accretion for this purely hydromagnetic braking effect.
Glucagon-like peptide-2 (GLP-2) is a nutrient-regulated intestinotrophic hormone derived from proglucagon in the distal intestine. Enteral nutrients (EN) potentiate the action of GLP-2 to reverse parenteral...Full Text Available
It is shown that the interaction of a class of positive energy tachyons decreases the area of the horizon of the T-S, delta = 3 metric even in the case of a reversible transformation (Msub(ir) = constant). This is a violation of the second law of black hole physics.
It is shown that the interaction of a class of positive energy tachyons decreases the area of the horizon of the T-S, delta = 3 metric even in the case of a reversible transformation (Msub(ir) = constant). This is a violation of the second law of black hole physics. (author).
Forward and reverse genetic experiments have both played important roles in revealing critical aspects of mammalian signal transduction pathways in cell culture experiments. Only recently have we begun...Full Text Available
BackgroundInferring regulatory interactions between genes from transcriptomics time-resolved data, yielding reverse engineered gene regulatory networks, is of paramount importance...Full Text Available
Thioredoxin, a small, ubiquitous protein which participates in redox reactions through the reversible oxidation of its active center dithiol to a disulfide, is an essential protein in Bacillus...Full Text Available
Ring opening dynamics of diarylethene derivative (BTF6) in n-hexane are studied by femtosecond transient absorption and time resolved spontaneous fluorescence techniques. Cyclo-reversion time constant is obtained.
Nitrate reductase from wheat (Triticum aestivum L. cv Bindawarra) leaves is inactivated by pretreatment with NADH, in the absence of nitrate, a 50% loss of activity occurring in 30...Full Text Available
The standards mapping methods are limited by the lack of information between surface measures and wells profiles. The cross well seismic survey has proven being an effective high-resolution method for reservoirs characterization due its high frequency band. In this work, a 2-D finite differences algorithm for numerical cross well seismic simulation was developed, based in the approach of 2nd order for the time derivatives and 4th order for the space derivatives. In relation to the imaging techniques, it was introduced a reverse time migration method based in the solutions of the wave equation in time for cross well seismic data by the method of the finite differences exclusively. The results of reverse time migration has showed that layers with 90 cm thickness for P-waves could be visualized in migrated sections with excellent resolution. The high frequency cross well seismic data combined with reverse time migration have ...
The etiology of major depression remains unknown, but dysfunction of serotonergic signaling has long been implicated in the pathophysiology of this disorder. p11 is an S100 family member recently...Full Text Available
Reverse genetics technology so far established for measles virus (MeV) is based on the Edmonston strain, which was isolated several decades ago, has been passaged in nonlymphoid cell lines, and is no...Full Text Available
We have measured the forward and reverse rates of the allosteric transition of hemoglobin A with three CO molecules bound by using modulated excitation coupled with fluorescence quenching of the DPG...Full Text Available
Neurological disorders induced by long-term exposure to organic solvents typically have a slowly progressive clinical course, which may be arrested or even reversed following discontinuation of exposure....Full Text Available
Several different neuronal populations are involved in regulating energy homeostasis. Among these, agouti-related protein (AgRP) neurons are thought to promote feeding and weight gain; however, the...Full Text Available
A heterobifunctional reagent, N-succinimidyl 3-(2-pyridyldithio)propionate, was synthesized. Its N-hydroxysuccinimide ester group reacts with amino groups and the 2-pyridyl disulphide structure reacts...Full Text Available
Brief exposures to red light induce far red-reversible changes of 5 to 10 millivolts magnitude in the upper 1 centimeter of etiolated Avena coleoptiles. The changes begin within 15...Full Text Available
A red light-induced, far red reversible stimulation of proton efflux from apical segments of etiolated Avena sativa L. cv. Victory coleoptiles was observed. The acidification...Full Text Available
Phenylketonuria (PKU) is a common genetic disorder in humans that arises from deficient activity of phenylalanine hydroxylase (PAH), which catalyzes the conversion of phenylalanine to tyrosine....Full Text Available
Multiglycosides of Tripterygium wilfordii Hook f (GTW), a Chinese herb-derived medicine used as a remedy for rheumatoid arthritis, are considered to be a reversible anti-fertility drug...Full Text Available
[Leu]- and [Met]enkephalin from thoracic ganglia of the shore crab Carcinus maenas have been purified to homogeneity by a reversed-phase HPLC procedure. Automated gas-phase sequencing revealed a primary...Full Text Available
Exercise-training might be a logical method to reverse muscle atrophy and weakness in patients treated with glucocorticoids. The purpose of the present investigation was to establish whether a treatment...Full Text Available
In chemostat culture, the virulence of two strains of Legionella pneumophila was shown to be significantly (P < 0.05) reduced when the culture temperature was lowered from 37 to 24 degrees C....Full Text Available
Peripheral vision has been the topic of few studies compared with central vision. Nevertheless, given that visual information covers all the visual field and that relevant information can...Full Text Available
OBJECTIVEHormonal contraceptives may adversely affect bone mineral density . However, racial differences and the reversibility of these changes are poorly understood....Full Text Available
Hydrolysis of olive oil by Chromobacterium viscosum lipase was studied in a reverse micellar system of a anionic surfactant Aerosol OT (AOT) and isooctane. Different methods of solubilization of the micellar system afford specific dependence of enzymatic activity of the lipase on the water content in the micelles. In an injection method, water content is controlled by the amount of injected water, which determines the micelle size and hydrophobicity of the micelle without salt addition and changes reversibly the conformation of lipase corresponding to the change of lipase activity. The activity reaches the maximum at a water content (water/AOT)of 7. In a phase transfer method, water content is determined by salt concentration in the aqueous phase in contact with micelles and the water content corresponding to the maximum activity is 12 to 13, below which the activity decrese drastically. Addition of taurodeoxycholic acid to the AOT micelles ...
Pseudomonas mandelii liquid cultures were studied to determine the effect of pH and temperature on denitrification gene expression, which was quantified by quantitative reverse transcription-PCR....Full Text Available
Realization that dental caries is a reversible, dynamic biochemical event at a micron level has changed the way the profession recognizes the caries disease and the caries lesion. The diagnosis of dental...Full Text Available
Reversible protein glutathionylation plays a key role in cellular regulation and cell signaling and protects protein thiols from hyperoxidation. Sulfiredoxin (Srx), an enzyme that catalyzes the reduction...Full Text Available
A simulation is developed that qualitatively describes the small-zone-gel-filtration behaviour of a reversibly associating protein. The results reflect the dependence of the apparent molecular weight...Full Text Available
An approach to generate mimics of phosphorylated serine proteins chemically through site-specific sulfonation of cysteine is presented. This chemical modification is reversible in the presence of reducing agent and therefore is analogous to the kinase/phosphatase system used in nature. PMID:21717004
A pigment-dispersing hormone (PDH) from eyestalks of the fiddler crab Uca pugilator has been purified by gel filtration, ion-exchange chromatography, partition chromatography, and reversed-phase...Full Text Available
In vivo, mammalian lenses have the capacity to effect fully reversible changes in shape, and possibly volume, during the accommodation process. Isolated lenses also change shape...Full Text Available
The antitumor agent camptothecin targets DNA topoisomerase I by reversibly stabilizing a covalent enzyme-DNA intermediate. The subsequent collision of DNA replication forks with these drug-enzyme-DNA...Full Text Available
Three popular imaging methods were used to carry out seismic migration from the Alberta foothills: Kirchhoff integral, reverse-time and explicit finite-difference migration methods. The imaging comparisons of reverse-time, Kirchhoff and f-x post-stack depth migration leads to the following conclusions. All of the three migration methods can provide acceptable and well-imaged intermediate results on the simplest model. Post-stack migration was not very sensitive to the accuracy of the velocity field once a reliable structural stack was available. With respect to the imaging accuracy and calculation cost, the Kirchhoff migration method seemed to be superior to reverse-time and f-x migration algorithms because its results on different kinds of velocity cases were basically kept coherent and consistent with the velocity model given by Mobil. Because of the lack of an accurate velocity field, reverse-time ...
Three popular imaging methods were used to carry out seismic migration from the Alberta foothills: Kirchhoff integral, reverse-time and explicit finite-difference migration methods. The imaging comparisons of reverse-time, Kirchhoff and f-x post-stack depth migration leads to the following conclusions. All of the three migration methods can provide acceptable and well-imaged intermediate results on the simplest model. Post-stack migration was not very sensitive to the accuracy of the velocity field once a reliable structural stack was available. With respect to the imaging accuracy and calculation cost, the Kirchhoff migration method seemed to be superior to reverse-time and f-x migration algorithms because its results on different kinds of velocity cases were basically kept coherent and consistent with the velocity model given by Mobil. Because of the lack of an accurate velocity field, reverse-time ...
Amino acids labelled with dimethylaminoazobenzenesulphonyl chloride can be separated by reversed-phase high-pressure liquid chromatography and detected in the visible region (436 nm). All 19 naturally...Full Text Available
As low temperature cryocoolers become more frequently used to cool superconducting magnets, it becomes increasingly apparent that the connection between the cooler and the magnet has an effect on the design and performance of the magnet. In general, the use of small coolers can be considered in two different temperature ranges; (1) from 3.8 to 4.8 K for magnet fabricated with LTS conductor and (2) from 18 to 35 K for magnets fabricated using HTS conductor. In general, both temperature ranges call for the use of a two-stage cooler. The best method for connecting a cooler to the magnet depends on a number of factors. The factors include: (1) whether the cooler must be used to cool down the magnet from room temperature, (2) whether the magnet must have one or more reservoirs of liquid cryogen to keep the ...
The conceptual design of an ohmically heated, reversed-field pinch (RFP) operating at /approximately/5-MW/m/sup 2/ steady-state DT fusion neutron wall loading and /approximately/124-MW total fusion power is presented. These results are useful in projecting the development of a cost effective, low input power (/approximately/206 MW) source of DT neutrons for large-volume (/approximately/10 m/sup 3/), high-fluence (3.4 MW yr/m/sup 2/) fusion nuclear materials and technology testing. 19 refs., 15 figs., 9 tabs.
This paper presents a reverse time migration (RTM) method for the migration of shot records in tilted transversely isotropic (TTI) media. It is based on the tilted TI acoustic wave equation that was derived from the dispersion relation. The RTM is a full depth migration allowing for velocity to vary laterally as well as vertically and has no dip limitations. The wave equation is solved by a tenth-order finite difference scheme. Using 2D numerical models, we demonstrate that ignoring the tilt angle will introduce both lateral and vertical shifts in imaging. The shifts can be larger than 0.5 wavelength in the vertical direction and 1.5 wavelength in the lateral direction.
A pre-stack migration algorithm for elastic waves in two-dimensional variable-velocity media is developed, implemented, and tested. The algorithm operates in the time-space domain and is based on reverse-time finite-difference extrapolation of elastic waves. The algorithm is explained and demonstrated in the context of imaging of elastic vertical seismic profile data, but is applicable to any source-recorder geometry. Synthetic test examples include a point diffractor, laterally homogeneous layers, and the flank of a salt dome.
Determination of the trajectory of a phase transition front moving in a forward or reverse direction is reduced to the solution of an ordinary differential equation. A numerical check of the results shows the method to be highly accurate. The method was used recently over a period of several years to solve various problems connected with the thawing of frozen rocks and their refreezing; among the problems considered was that of the ablation of rocks during the channeling of well, in which the method invariably proved its effectiveness. This furnishes a basis for recommending it for broader usage.
Waste electrical and electronic equipment (WEEE) is recognized as a priority waste stream internationally, mostly due to their volume and hazardousness. This paper presents an analysis for the quantification of WEEE management cost for Greece, taking into consideration scenarios for reverse logistics network's development and WEEE volume scenarios. Transportation cost, which represents a major cost element for any reverse logistics network, is modelled with the use of mathematical programming, targeting towards the optimization of locations for the development of required intermediate storage infrastructures. Additionally, overall operational cost and recycling fees are estimated. PMID:21242175
The paper presents an integrated approach to the problem of electron temperature diagnostics of the plasma in a reversed field pinch. Three different methods, sampling different portions of the electron distribution function, are adopted, namely Thomson scattering, soft X-ray spectroscopy by pulse-height analysis and filtered soft X-ray intensity ratio. A careful analysis of the different sources of systematic errors is performed and a novel statistical approach is adopted to mutually validate the three independent measurements. A satisfactory agreement is obtained over a large range of experimental conditions, indicating that in the plasma core the energy distribution function is well represented by a maxwellian. (author)
We propose unsteady-state reverse osmosis cell modelling in two dimensions. The convection-diffusion equation describing the concentration of the relevant chemical species is solved by a finite difference technique, while the velocity field is described by empirical expressions for spiral-wound membrane cells. A non-constant permeability is introduced to take into account the effects of membrane compaction at high operating pressures. The role of concentration polarization is discussed for different values of the parameters describing the global process. Finally, the model is applied to predict the effects of a pulsating flow where a cyclic pressure feed is adopted to enhance the permeate flux. In this context, an experimental validation of the model is proposed.
The use of reversible pump/turbine sets in pumped storage has created a requirement for rapid reversibility. Softstart technology, based on static frequency converters (SFC) has evolved to such an extent that it is now the best choice for serving this purpose, both from a technical and from an economic point of view. The objective of our paper is to give the owners of pumped storage plants and those persons responsible for the selection, the operation or the maintenance of the electrical equipment the necessary insight into the SFC functions, features and all other application related aspects, to facilitate their decision making process. Case studies are included.
Trastuzumab increases survival amongst women with human epidermal growth factor receptor (HER)-2 receptor positive metastatic breast cancer, but maternal and fetal risks are associated with advanced disease and its treatment in pregnancy. We present a case of a primigravid with HER-2 positive metastatic breast cancer who received trastuzumab throughout pregnancy. She presented with cerebral metastases, requiring surgical decompression and resection. Reversible oligohydramnios developed during pregnancy. Fetal safety data on trastuzumab in pregnancy is limited, but case reports suggest a recurring pattern of (mostly reversible) oligohydramnios.
An efficient method of hydrogen storage in nano-porous carbons is its reversible sorption by electrochemical decomposition of a KOH water solution [1-3] according to the following equation: C + xH{sub 2}O + xe{sup -} {yields} (CH{sub x}) + xOH{sup -} where (CH{sub x}) stands for the hydrogen inserted into the nano-porous carbon during charging and oxidized during discharging. Although various carbon materials have been investigated as hydrogen adsorbents, the information about the storage mechanism as well as the nature of the hydrogen/carbon interaction is still not sufficient. In order to extend the understanding of the process, carbon samples charged electrochemically were investigated by temperature programmed desorpt(TPD). The nature of the hydrogen/carbon interaction was studied by electrochemical analysis at different temperatures. The TPD experiments consist of heating the samples from room temperature to 950 C and of quantitative ...
Measurements of the magnetic susceptibility betweeen 0.03 and 300 K and of the magnetization between 0.05 and 10 K for magnetic fields up to 60kOe have been used to investigate effects from the interaction between the conduction electrons and local magnetic moments in (Lasub(1-x)Cesub(x))B_6 alloys (0.0007<=x<=0.10). For Ce concentrations x<0.006 the data show Kondo-type single impurity behaviour at low temperatures with a transition from a magnetic to a non-magnetic regime of the Ce ions. In the magnetic regime the impurity susceptibility follows a Curie-Weiss law, and in the non-magnetic regime it varies with T"2. An external magnetic field gradually restores the free-ion behaviour of the Ce impurities. For more concentrated alloys interactions between the impurities are observed. The RKKY ...
The magnetic separation technology using sub-microsized ferromagnetic particle is indispensable in many areas of medical biosciences. For example, ferromagnetic particles (200-500 nm) are widely used for cell sorting in stem cell research with the use of cell surface-specific antigens. Nanosized ferromagnetic particles (10-20 nm) have been suggested as more suitable in drug delivery studies given their efficiency of tissue penetration, however, the magnetic separation method for them has not been established. One of the major reasons is that magnetic force acting on the object particles decreases drastically as a particle diameter becomes small. In this study, magnetic force acting on the targets was enhanced by the combination of superconducting magnet and the filter consisting of ferromagnetic particle. By doing so, we confirmed that Fe{sub 3}O{sub 4} of 20 nm in diameter was ...
With "1"5"1Eu-Moessbauer spectroscopy and other methods the complex magnetic properties of Eu_2PdSi_3, arising from the two crystallographically different lattice sites of the Eu"2"+ ions, have been already studied. Here we study the impact of magnetic dilution of the magnetic Eu"2"+ sites by non-magnetic Y"3"+ ions. A previous specific heat study has found reduced magnetic ordering temperatures with strong indication of disorder effects like in magnetic spin glasses. Here we provide from "1"5"1Eu-Moessbauer spectroscopy detailed information of the impact of Y"3"+ substitution on the magnetic properties of the two lattice sites, well distinguishable in the "1"5"1Eu-spectra. Since the substitution of the larger Eu"2"+ ions by the smaller Y"3"+ ions is connected with a lattice contraction, we also applied high pressure to the Eu_2PdSi_3 sample ...
The aim of the paper is to review the role of interventional radiology in the management of hemodialysis vascular access and complications in renal transplantation. The evaluation of patients with hemodialysis vascular access is complex. It includes the radiology/ultrasound (US) evaluation of the peripheral veins of the upper extremities with venous mapping and the evaluation of the central vein prior to the access placement and radiological detection and treatment of the stenosis and thrombosis in misfunctional dialysis fistulas. Preoperative screening enables the identification of a suitable vessel to create a hemodynamically-sound dialysis fistula. Clinical and radiological detection of the hemodynamically significant stenosis or occlusion demands fistulography and endovascular treatment. Endovascular prophylactic dilatation of stenosis greater than 50% with associated clinical abnormalities such as flow-rate reduction is warranted to prolong access patency. The technical success ...
The electrical resistivity, Hall effect, and magnetic susceptibility of single-crystal UPd_2Si_2 have been studied between 4.2 and 300 K. A large anisotropy was observed in both the magnetic and transport properties. There is a quadratic temperature dependence of the resistivity for a range of temperatures between 4.2 and 80 K. At higher temperatures, the resistivity indicates a Kondo-type behavior. The behavior of these quantities is accounted for by the magnetic phase transitions at 108 and 136 K reported from neutron-scattering studies. At high temperatures, the magnetic susceptibility of UPd_2Si_2 is Curie-Wiess-like along the c axis. The temperature dependence of the Hall coefficient above 108 K is accounted for by a theoretical model invoking skew scattering of conduction electrons by localized magnetic moments.
The electrical resistivity, Hall effect, and magnetic susceptibility of single-crystal UPd[sub 2]Si[sub 2] have been studied between 4.2 and 300 K. A large anisotropy was observed in both the magnetic and transport properties. There is a quadratic temperature dependence of the resistivity for a range of temperatures between 4.2 and 80 K. At higher temperatures, the resistivity indicates a Kondo-type behavior. The behavior of these quantities is accounted for by the magnetic phase transitions at 108 and 136 K reported from neutron-scattering studies. At high temperatures, the magnetic susceptibility of UPd[sub 2]Si[sub 2] is Curie-Wiess-like along the [ital c] axis. The temperature dependence of the Hall coefficient above 108 K is accounted for by a theoretical model invoking skew scattering of conduction electrons by localized magnetic moments.
The Recycler ring magnet will be made of Strontium ferrite permanent magnets. A strontium ferrite permanent magnet without compensation has a temperature coefficient of -0.2 % in dB/dT. To compensate this effect, we are utilizing 30 % Ni 70 % Fe alloy, a temperature compensation ferromagnetic material with a low Curie point. To search for optimum commercially available material and optimum condition, we made a couple of simple model magnets, and tested with several different compensating material. The test results are reported and its optimal conditions are shown. Several different configurations were tested including a possible 2 kG magnet configuration.
We report on the magnetic hyperthermia properties of chemically synthesized ferromagnetic 11 and 16 nm Fe(0) nanoparticles of cubic shape displaying the saturation magnetization of bulk iron. The specific absorption rate measured on 16 nm nanocubes is 1690+-160 W/g at 300 kHz and 66 mT. This corresponds to specific losses-per-cycle of 5.6 mJ/g, largely exceeding the ones reported in other systems. A way to quantify the degree of optimization of any system with respect to hyperthermia applications is proposed. Applied here, this method shows that our nanoparticles are not fully optimized, probably due to the strong influence of magnetic interactions on their magnetic response. Once protected from oxidation and further optimized, such nano-objects could constitute efficient magnetic cores for biomedical applications requiring very large heating power.
The magnetic properties of polycrystalline and single crystalline rare earth transition metal silicides Gd_xLa_1_-_xMSi (M =Fe, Co) were investigated. Magnetic measurements have been made in static magnetic fields up to 13 kOe and in pulsed magnetic fields up to 250 kOe in the temperature range from 4.2 to 350 K. The magnetic susceptibility in the paramagnetic state of all the investigated compounds obeys the Curie-Weiss law except for LaFeSi and LaCoSi. Increase of the La content in Gd_xLa_1_-_xFeSi compounds leads to a decrease of the Curie and Neel temperatures, which can be explained by a decrease of positive exchange interactions. (orig.).
Sensitive and quick-response nonlinear inductance characteristics are found for high Tc superconducting (YBa/sub 2/Cu/sub 3/O/sub 7-chi/) disk cores at 77K in which soft magnetic BH hysteresis loops are observed. Various quick response magnetic devices such as modulators, amplifiers and sensors are built using these cores. The magnetizing frequency can be set to more than 20 MHz, which is difficult for conventional ferromagnetic bulk materials such as Permalloy amorphous alloys and ferrite. New quick-response fluxgate type magnetic-field sensors are made using ac and dc voltage sources. The former is used for second-harmonic type sensors, while the latter is for voltage-output multivibrator type sensors. Stable and quick-response sensor characteristics were obtained for two-core type multivibrators.
The Advanced Photon Source injector synchrotron is a 7-GeV positron machine with a standard alternating gradient lattice. The calculated effect of dipole magnet strength errors on the orbit distortion, simulated by Monte Carlo, was reduced by sorting pairs of magnets having the closest simulated measured strengths to reduce the driving the term of the integer resonance nearest the operating point. This method resulted in a factor of four average reduction in the rms orbit distortion when all 68 magnets were sorted at once. The simulated effect of magnet measurement experimental resolution was found to limit the actual improvement. The {Beta}-beat factors were similarly reduced by sorting the quadrupole magnets according to their gradients.
We investigated the magnet field dependence of the X-ray pulse height and the critical current of a Ti/Au bilayer TES micro-calorimeter. The pulse height was strongly affected by the magnetic field intensity applied perpendicularly to the TES surface. We found that the critical current at zero temperature, I c0, decreased by a factor of two by applying a magnet field of ?10??T. Our data are consistent with a TES sensitivity proportional to (I/I c0)?2/3, as predicted by the Ginzburg-Landau theory. This fact implies that the shape of the R?T curve of the TES is partly determined by the critical current of the superconductor. In order to make our TES microcalorimeters less sensitive to the external magnetic field, we fabricated devices equipped with on-chip magnetic shielding. One device has ...
The Large Hadron Collider (LHC) will be equipped with several thousands of superconducting corrector magnets. Among the largest ones are the superconducting trim quadrupoles (MQTL). These twin-aperture magnets with a total mass of up to 1700 kg have a nominal gradient of 129 T/m at 1.9 K and a magnetic length of 1.3 m. Sixty MQTL are required for the LHC, 36 operating at 1.9 K in and 24 operating at 4.5 K. The paper describes the design features, and reports the measured quench performance and magnetic field quality of the production magnets. The MQTL magnet production is shared between CERN and industry. This sharing is simplified due to the modular construction, common to all twin-aperture correctors.
1. In order to carry out isothermic crystal growth experiments of YBCO the 123 primary crystallization field was determined by means of phase diagram investigations and crystal growth experiments at different oxygen partial pressure. 2. YBCO single crystals of high crystallographic perfection were grown and conclusions on the flux pinning mechanism were drawn. 3. By means of Liquid Phase Epitaxy (LPE) single crystalline (Tc{approx}90 K; {Delta}T{<=}0.5 K) c- and a,b- YBCO fils have been prepared on NdGaO{sub 3} and LaGaO{sub 3} substrates. The films were characterized structurally and magnetically. 4. Our fist melt textured YBCO ``single crystals`` possess intracrystalline critical current densities >10{sup 4} A/cm{sup 2} at B{<=}2T. The irreversibility inductions are {<=}6 T at 77 K. A simple demonstrator was constructed together with the IFW Dresden and a growth model was developed. 5. Using above all torque magnetometer ...
Effect of low-frequency pulsating magnetic field on the microstructure and magnetic properties of amorphous alloy Fe_7_8Si_9B_1_3 were investigated. The temperature rise induced by the treatment was measured by a non-contact infrared thermometer. The crystallization behavior and microstructure of specimens were studied by Moessbauer spectroscopy and transmission electron microscope (TEM). Magnetic properties of the specimens were investigated by alternating gradient magnetometer (AGM). The results show that the low-frequency pulsating magnetic field can promote the single-phase crystallization of amorphous alloy Fe_7_8Si_9B_1_3. The frequency, f of applied field is from 10 to 40 Hz, magnetic field, H is from 0.02 to 0.04 T and treatment duration, t is from 180-300 s. The volume fraction of crystallization phase (#alpha#-Fe(Si), the grain size, 2-10 nm) is 3-7%. The temperature rise ...
This paper discusses the possible detection of magnetic monopoles and monopole tachyons. Topics considered include insects, astrophysics, general relativity theory, plants, and biotechnology. The paper was presented at an international symposium on non-conventional energy technology.
The investigated hybrid nanocomposite consists of a porous silicon template with electrochemically embedded Ni or Co nanostructures and offers magnetic characteristics which can be tailored by the electrochemical process parameters during fabrication. A twofold magnetic behaviour can be observed, a first one due to the spinmagnetism at magnetic fields below the saturation magnetization of the deposited metals and a second non-saturating term at higher fields (>1 T up to 7 T) above the saturation magnetization. In case of Ni deposited within the pores this non-saturating term shows a paramagnetic characteristic and follows exactly the Curie-Weiss law, whereas for Co/porous silicon samples the temperature dependent magnetization shows some deviations from the Curie Weiss law. In this high field region a difference in the temperature dependence between Ni ...
The Time Projection Chamber (TPC) magnet at LBL and its compensation solenoids are adiabatically stable superconducting solenoid magnets. The cryogenic system developed for the TPC magnet is discussed. This system uses forced two-phase tubular cooling with the two cryogens in the system. The liquid helium and liquid nitrogen are delivered through the cooled load by forced tubular flow. The only reservoirs of liquid cryogen exist in the control dewar (for liquid helium) and the conditioner dewar (for liquid nitrogen). The operation o these systems during virtually all phases of system operation are described. Photographs and diagrams of various system components are shown, and cryogenic system data are presented in the following sections: (1) heat leaks into the TPC coil package and the compensation solenoids; (2) heat leaks to various components of the TPC magnet cryogenics system besides the ...
A new type of radiation which occurs when particles are accelerated in the field of a longitudinal wave and in a transverse magnetic field is studied. The characteristics of such spontaneous radiation are obtained, and the influence of collective effects on the radiation is analyzed. The application of the findings to the theory of free electron lasers is discussed. 8 references.
BackgroundMagnetic Resonance Imaging scanners have become ubiquitous in hospitals and high-field systems (greater than 3 Tesla) are becoming increasingly common. In light of recent...Full Text Available
The magnetic susceptibility and the density of human oxy-(HbO2) and carbonmonoxyhemoglobin (HbCO) solutions of various concentrations have been measured at room temperature, with pure water...Full Text Available
OBJECTIVES: This article uses meta-analysis methodology to examine the statistical consistency and importance of random variation among results of epidemiologic studies of residential magnetic field...Full Text Available
The magnetic properties of as-grown Ga1-xMnxAs have been investigated by the systematic temperature and magnetic field dependent soft x-ray magnetic circular dichroism (XMCD) measurements in the Mn L2,3 absorption edge region. The XMCD intensity at high temperatures obeys the Curie-Weiss law, but residual spin magnetic moment appears already around 100 K, significantly above Curie temperature (Tc), suggesting that short-range ferromagnetic correlations are developed significantly above Tc. The high-field magnetic susceptibility becomes T-independent below TC, indicating that the AF interaction between the substitutional Mn (Mnsub and interstitial Mn (Mnint) ions, which becomes strong as the Mn concentration x increases, exists and that the amount of the Mnint affects Tc. The present experimental findings should give valuable insight into the inhomogeneous ...
OBJECTIVES: To define a method for measurement of the cross sectional area and volume of the quadriceps femoris muscle using magnetic resonance imaging (MRI) in conjunction with stereology, and to compare...Full Text Available
Major breakthroughs have recently been reported that can help overcome two inherent drawbacks of NMR: the lack of sensitivity and the limited memory of longitudinal magnetization. Dynamic nuclear polarization...Full Text Available
Quantitative probing of heterogeneous regions in muscle is feasible with phosphorus-31 magnetic resonance spectroscopy because of the differentiation of metabolic patterns of glycolytic and oxidative...Full Text Available
OBJECTIVES: To appraise epidemiological evidence of the purported association between residential exposure to power frequency magnetic fields and adult cancers. METHODS: Literature review and epidemiological...Full Text Available
Epidemiologic research concerning electric and magnetic fields in relation to cancer has focused on the potential etiologic roles of residential exposure on childhood cancer and occupational exposure...Full Text Available
The purpose of this study was to assess the effect of a 735-kV transmission line on the electric and magnetic field exposures of people living at the edge of the line's right of way. Exposure of 18...Full Text Available
Bone metastases of an Ewing's sarcoma were detected by magnetic resonance imaging (MRI), when bone scan, CT and plain films were still normal. This is due to the ability of MRI to detect intramedullary metastases before involvement of the cortex. (Auth.).
The magnetically controlled plasma opening switch (MCPOS) is an advanced plasma opening switch that utilizes magnetic fields to improve operation. Magnetic fields always dominate terawatt, pulsed power plasma opening switches. For that reason, the MCPOS uses controlled applied magnetic fields with magnitude comparable to the self-magnetic field of the storage inductor. One applied field holds the plasma in place while energy accumulates in the storage inductor, then another applied field pushes the plasma away from the cathode to allow energy to flow downstream. Over a ten month period, an MCPOS was designed, built, and tested on DECADE Module 2 at Physics International. The peak drive current was 1.8 MA in 250 ns. The output parameters were up to 1 MA into an electron beam load. The radiation temporal pulse width averaged 60 nanoseconds full-width at half-maximum. The peak load ...
A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for assessment of age-related structural changes (dentin and pulp) of human teeth in...Full Text Available
OBJECTIVES--This case cohort study examines whether there is an association between exposure to electric and magnetic fields and suicide in a population of 21,744 male electrical utility workers from...Full Text Available