Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MAGNETICS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources
PubMed1998

A magnetic evaluation of peripheral nerve regeneration: I. The discrepancy between magnetic and histologic data from the proximal segment.

Histologic techniques can quantify the number of axons in a nerve, but give no information about electrical conductibility. The number of functional myelinated neuronal units in a nerve can be quantified based on a magnetic recording technique. When studying reconstructed peripheral nerves a significant difference between the results found with these two techniques can be observed. A comparison was made between the long-term changes in the number of histologically and magnetoneurophysiologically measured neuronal units proximal to a nerve reconstruction. This study was performed on 6 New Zealand White rabbits, 20 weeks after the peroneal nerve had been reconstructed. The contralateral nerves were used as a control. Histologic examination demonstrates a statistically significant decrease of approximately 5% in the number of myelinated fibers. The magnetoneurophysiological results demonstrate a decrease which is estimated to be caused by the loss of approximately 50% of the functional myelinated neuronal units in the nerve. Therefore we conclude that of the initially available myelinated neuronal units, 5% degenerate completely, 45% are vital but lose their signal conducting capability, and the remaining 50% are vital and continue to conduct signals. Apparently, only this latter group of 50% of the initially available functional neuronal units appears to remain available for functional recovery.

Animals↗
PubMed2001

Optically active molecule-based magnets: enantioselective self-assembling, optical, and magnetic properties.

In this short communication we describe the synthesis and the optical and magnetic properties of optically active three dimensional (3D) bimetallic [Cr-Mn] networks [[Delta Cr(III) Delta Mn(II)(ox)(3)][Delta Ru(II)(bpy)(3)]ClO(4)](n)1 - Delta, [[Lambda Cr(III)Lambda Mn(II)(ox)(3)][Lambda Ru(II) (bpy)(3)]ClO(4)](n) 1 - Lambda and [[Delta Cr(III)Delta Mn(II)(ox)(3)][Delta Ru(II)(bpy)(2)p p y]](n) 2 - Delta,[[Lambda Cr(III)Lambda Mn(II)(ox)(3)][Lambda Ru(II)(bpy)(2)ppy]](n) 2 - Lambda (ox = oxalate, bpy = bipyridine, ppy = phenyl-pyridine).

Journal Article↗
PubMed2006

Childhood leukemia and magnetic fields in Japan: a case-control study of childhood leukemia and residential power-frequency magnetic fields in Japan.

Residential power-frequency magnetic fields (MFs) were labeled as a possible human carcinogen by the International Agency for Research on Cancer panel. In response to great public concern, the World Health Organization urged that further epidemiologic studies be conducted in high-exposure areas such as Japan. We conducted a population-based case-control study, which covered areas inhabited by 54% of Japanese children. We analyzed 312 case children (0-15 years old) newly diagnosed with acute lymphoblastic leukemia (ALL) or acute myelocytic leukemia (AML) in 1999-2001 (2.3 years) and 603 controls matched for gender, age and residential area. Weekly mean MF level was determined for the child's bedroom. MF measurements in each set of a case and controls were carried out as closely in time as possible to control for seasonal variation. We evaluated the association using conditional logistic regression models. The odds ratios for children whose bedrooms had MF levels of 0.4 microT or higher compared with the reference category (MF levels below 0.1 microT) was 2.6 (95% CI=0.76-8.6) for AML+ALL and 4.7 (1.15-19.0) for ALL only. Controlling for some possible confounding factors did not alter the results appreciably. Even an analysis in which selection bias was maximized did not fully explain the association. Most of the leukemia cases in the highest exposure category had MF levels far above 0.4 microT. Our results provided additional evidence that high MF exposure was associated with a higher risk of childhood leukemia, particularly of ALL.

Acute Disease↗
PubMed1997

Preparation of Magnetic Inks: Adsorption of Macromolecular Dispersion Agents on Magnetic Metallic Iron Pigments and Electrical Charge Formation

The interaction between metallic iron pigments (MPs) and the actual constituents of magnetic ink is examined by first determining the adsorption isotherms and analyzing by FTIR the type of bonding that is established between the constituents and MP. Then, following the approach described in a previous paper using model compounds, the formation of electrical charges on MPs is examined through acoustophorometric (Electrokinetic amplitude or ESA) measurements. It is shown that the variation in ESA is related to charge transfer processes and reflects the MP-constituent interactions. Finally, adsorption competitions are shown and the importance of the method of preparation (order of mixing of the ingredients of the ink) is illustrated. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed2000

Nuclear magnetic resonance in inhomogeneous magnetic fields

The response of the spin system has been investigated by numerical simulations in the case of a nuclear magnetic resonance (NMR) experiment performed in inhomogeneous static and radiofrequency fields. The particular case of the NMR-MOUSE was considered. The static field and the component of the radiofrequency field perpendicular to the static field were evaluated as well as the spatial distribution of the maximum NMR signal detected by the surface coil. The NMR response to various pulse sequences was evaluated numerically for the case of an ensemble of isolated spins (1/2). The behavior of the echo train in Carr-Purcell-like pulse sequences used for measurements of transverse relaxation and self-diffusion was simulated and compared with the experiment. The echo train is shown to behave qualitatively differently depending on the particular phase schemes used in these pulse sequences. Different echo trains are obtained, because of the different superposition of Hahn and stimulated echoes forming mixed echoes as a result of the spatial distribution of pulse flip angles. The superposition of Hahn and stimulated echoes originating from different spatial regions leads to distortions of the mixed echoes in intensity, shape, and phase. The volume selection produced by Carr-Purcell-like pulse sequences is also investigated for the NMR-MOUSE. The developed numerical simulation procedure is useful for understanding a variety of experiments performed with the NMR-MOUSE and for improving its performance. Copyright 2000 Academic Press.

Journal Article↗
PubMed1980

Magnetic circular dichroism on oxygen complexes of hemoproteins: correlation between magnetic circular dichroism magnitude and electronic structures of oxygen complexes.

Magnetic circular dichroism (MCD) and natural circular dichroism (CD) spectra are reported for horseradish peroxidase Compounds II and III, and kangaroo myoglobin Compound II at pH values of 8.5 and 4.9. These compounds exhibited MCD spectra of apparent Faraday A term both in the Soret and Q regions, except for myoglobin compounds in the Soret region where intrinsic temperature dependence showed large contribution from Faraday C terms. Comparison of these data with the MCD spectra of the dioxygen complexes of hemoglobin (myoglobin) and cytochrome P-450 revealed that the magnitude of the apparent Faraday A term trough at the Q0-0 bands decreased in the order of O2 complexes of hemoglobin (myoglobin) ([theta]M not equal to 16) greater than horseradish peroxidase Compound III ([theta]M not equal to 8) greater than O2 complex of cytochrome P-450 ([theta]M not equal to 4). The [theta]M values of the oxygen complex of cytochrome P-450 is similar to those observed for the compounds II of horseradish peroxidase and kangaroo myoglobin. From these observations it was concluded that the magnitude of MCD, especially the trough depth of the Q0-0 band, has direct correlation to the electronic states of the oxygen complexes of the hemoproteins. The implication of the findings was discussed in terms of the iron electronic structures perturbed by the axial ligation.

Animals↗
PubMed2000

[Comparison of mouth pressure, twitch, after anterior magnetic stimulation against posterior magnetic stimulation in healthy subjects].

BACKGROUND: If techniques for studying respiratory muscle function are easy to use and well tolerates by patients, they can be used routinely. Measuring mouth twitches (TwM) using either bilateral anterior or posterior magnetic stimulation meets both criteria. SUBJECTS AND METHODS: We studied 16 healthy subjects. TwM was measured using bilateral anterior (TwMA) and posterior (TwMP) stimulation. Ten stimuli were applied for each technique for each subject. Five subjects repeated the test was repeated on a different day. RESULTS: The mean TwMA in healthy subjects was 21.07 +/- 4.4 cmH2O (range 13.72-30.11); the mean TwMP was 21.12 +/- 5.9 cmH2O (range 12.7-35.7) (NS). The mean difference was 2.8 +/- 2.5 cmH2O, while the ratio TwMP/PImax was 0.15 (range 0.08-0.10) and TwMA/PImax was 0.14 (range 0.07-0.15). The correlation between the two technique was 0.8. The patients who underwent testing twice had a mean TwMA of 20 cmH2O on the first day and 10.18 cmH2O on the second (NS). The coefficient of variation (CoV%) was 5.9% for TwMA and 7.2% for TwMP. CONCLUSIONS: The two techniques for measuring TwM give similar results and coefficients of variation in healthy subjects; either technique can be used. Variation from one testing day to another is low.

Adult↗
PubMed2002

Iron pentacarbonyl as a precursor for molecule-based magnets: formation of Fe[TCNE](2) (T(c) = 100 K) and Fe[TCNQ](2) (T(c) = 35 K) magnets.

The reaction of tetracyanoethylene (TCNE) and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) with Fe(CO)(5) leads to formation of magnetically ordered materials of Fe[TCNE](2) (T(c) = 100 K) and Fe[TCNQ](2) (T(c) = 35 K) composition, respectively. In contrast, the reaction with 1,2-dichloro-5,6-dicyanobenzoquinone (DDQ) leads to a paramagnetic material.

Journal Article↗
PubMed2002

Magnetic ordering in the rare earth molecule-based magnets, Ln(TCNE)(3) (Ln = Gd, Dy; TCNE = tetracyanoethylene).

The reaction of LnI(3) x xMeCN (Ln = Gd, Dy) and TCNE (tetracyanoethylene) in acetonitrile forms Ln(2)[C(4)(CN)(8)](3) x xMeCN. These paramagnetic light-colored solids contain the S = 0 octacyanobutandiide dianion, [C(4)(CN)(8)](2-), which upon desolvation of these products forms dark green Ln(TCNE)(3). In these compounds the central C[bond]C sigma bond in [C(4)(CN)(8)](2-) is broken, re-forming S = 1/2 [TCNE]*(-). as evidenced by the color change and the infrared spectra. Ln(TCNE)(3) exhibit coupling between Ln(3+) and [TCNE]*(-) and magnetically order as ferrimagnets at 8.5 (Dy) and 3.5 (Gd) K.

Journal Article↗
PubMed2003

Synthesis, structure, and magnetic properties of [MnIII(salpn)NCS]n, a helical polymer, and the dimer [MnIII(salpn)NCS]2. Weak ferromagnetism in [MnIII(salpn)NCS]n related to the strong magnetic anisotropy in Jahn-Teller MnIII (salpnH2 = N,N'-bis(salicylidene)-1,3-diaminopropane).

Dimeric [Mn(salpn)NCS](2)(1) and polymeric [Mn(salpn)NCS](n)(2) are formed by the reaction of Mn(CH(3)CO(2))(2).4H(2)O, the schiff base, and thiocyanate. The formation of the two polymorphic forms is solvent and temperature dependent. 1: orthorhombic, space group Pbca, with a = 12.573(2) A, b = 13.970(7) A, c = 18.891(9) A, and Z = 8. 2: orthorhombic, space group Pna2(1), with a = 12.5277(14) A, b = 11.576(2) A, c = 11.513(2) A, and Z = 4. The dimers in 1 are held together by weak noncovalent S...pi (phenyl) interactions leading to a chain along the a-axis. Each monomeric unit of the polymer in 2 is related to its adjacent ones by a 2-fold screw axis leading to a helix along the c-axis. The exchange coupling is nondetectable in the dimer. The magnetic susceptibility of the helical chain fits a classical chain law with J = -3.2 cm(-1) and shows a weak ferromagnetic ordering below 7 K due to spin canting effects.

Journal Article↗
PubMed2004

Intermolecular magnetic couplings in the dinuclear copper(II) complex mu-chloro-mu-[2,5-bis(2-pyridyl)-1,3,4-thiadiazole] aqua chlorocopper(II) dichlorocopper(II): synthesis, crystal structure, and EPR and magnetic characterization.

Mu-chloro-mu-[2,5-bis(2-pyridyl)-1,3,4-thiadiazole] aqua chlorocopper(II) dichlorocopper(II) is the first characterized dimeric complex of a transition metal and this hetero ligand [C(12)H(10)Cl(4)Cu(2)N(4)OS; triclinic; space group P; a = 9.296(3) A, b = 9.933(3) A, c = 10.412(3) A; alpha = 79.054(5) degrees, beta = 82.478(6) degrees, gamma = 67.099(5) degrees; Z = 2 at room temperature]. The Cu(II) ions are bridged by the N-N thiadiazole bond and a chloride ion [Cu1-Cu2 = 3.7800(8) A]. Thermogravimetric analysis shows this structure to be stable at temperatures up to 348 K. At higher temperatures, the successive loss of a water molecule and one chloride of the dimeric unit is identified. From room temperature to 125 K, half of the Cu(2+) ions are progressively engaged in intermolecular dinuclear antiferromagnetic exchanges, while the other half remain paramagnetic. At lower temperatures, both susceptibility and electron paramagnetic resonance measurements show the paramagnetic-only couplings of this half of the Cu(2+) ions, involving a singlet ground state for interacting Cu(2+). This unusual behavior has been satisfactorily explained on the basis of intermolecular Cu-Cu interactions (J = -180 cm(-1)), involving the magnetic d(z)2 orbital perpendicular to the molecular plane, on which are seen the conjugate effects of the bridging chloride and the planar thiadiazole. It is noteworthy that the behavior of the title compound is original, compared to the systematic in-plane intramolecular antiferromagnetic coupling of other thiadiazole-containing binuclear complexes.

Journal Article↗
PubMed2004

Intra and intermolecular magnetic interactions in a series of dinuclear Cu(II)/hxta complexes [H5hxta = N,N'-(2-hydroxy-1,3-xylylene)-bis-(N-carboxymethylglycine)]: correlation of magnetic properties with geometry.

Nine dinuclear copper(II) complexes with hxta5- ligands [H5hxta = N,N'-(2-hydroxy-1,3-xylylene)-bis-(N-carboxymethylglycine)]: [Cu2(MeO-hxtaH)(H2O)2] x 4H2O (1), [Na(micro-H2O)2(H2O)6][Cu2(Cl-hxta)(H2O)3]2 x 6H2O (2), [Cu(H2O)6][Cu2(Me-hxta)(H2O)2](NO3) x 2H2O (3), [Cu2(R-hxtaH)(H2O)3] x 3H2O [R = Cl (4), CH3 (5), and MeO (6)], [Cu2(MeO-hxtaH2)(micro-X)(CH3OH)] x 3CH3OH [X = Cl (7), Br (8)] and K5Na(micro-H2O)10[Cu2(micro-CO3)(Me-hxta)]2 x 4H2O (9), have been synthesized and structurally characterized. In complexes 4-7, the dinuclear units are linked via novel pairwise supramolecular interactions involving the ligand carboxylate groups. The intra- and intermolecular magnetic interactions have been quantified, and the coupling constants have been related to the structural geometries.

Copper↗
PubMed2004

Magnetic nanoparticles through organometallic synthesis: evolution of the magnetic properties from isolated nanoparticles to organised nanostructures.

Co and NiFe nanoparticles (2.7 to 3.3 nm mean diameter) of narrow size distribution have been obtained through the decomposition of organometallic precursors in organic solutions of long alkyl chain ligands, namely oleic acid and hexadecylamine. Materials of various volume fractions were produced. The particles have been structurally characterised by WAXS. Both adopt the bulk structure: HCP in the case of cobalt; a mixture of FCC and BCC for NiFe. Their aptitude to self-assemble either on flat supports or in bulk solid state has been investigated by means of TEM and SAXS. This study suggests the crystallisation of the nanoparticles upon solvent evaporation, especially a local FCC arrangement was observed for the NiFe material. Magnetic measurements (SQUID) confirm this tendency. The blocking temperature depends on the metal volume fraction, i.e. on the anisotropy generated by the dipolar couplings (Ki). We show that, for dense samples, the particles of high intrinsic anisotropy, Ku, (Co) still display an individual behaviour while the soft ones (NiFe) display a collective behaviour.

Journal Article↗