Search results for "Magnetism"
showing 10 items of 1934 documents
Synthesis Crystal Structure and Magnetic Properties of the Trinuclear Nickel(II) Complex Bis[(μ-thiocyanato-N)bis(μ-pyridazine-N1,N2)bis(thiocyanato-…
2000
Unusual single N-bridging thiocyanato and double pyridazine (pdz) bridges occur in the linear trinuclear nickel(II) complex of formula [Ni3(pdz)6(NCS)6]. The compound exhibits a quasi Curie law behavior, the antiferromagnetic coupling through the double 1,2-diazine links being nearly compensated by the ferromagnetic exchange through the single N-bridging thiocyanato.
Synthesis, Characterization and Magnetic Properties of New Dinuclear Copper(II) Complexes with N,N′-Disubstituted Dithiooxamides derived from α-Amino…
2005
Four new dinuclear copper(II) complexes have been synthesized and have the general formula [Cu2(L)(H2O)2], where L = GLYDTO [N,N′-bis(carboxymethyl)dithiooxamide], ALADTO [N,N′-bis(carboxyethyl)dithiooxamide], VALDTO [N,N′-bis(1-carboxy-2-methylpropyl)dithiooxamide] and LEUDTO [N,N′-bis(1-carboxy-3-methylbutyl)dithiooxamide]. The complexes were characterized by elemental analysis as well as by IR, electronic and EPR spectroscopy. These techniques provided evidence for the presence of the CuNO2S chromophore. Magnetic susceptibility measurements on all the complexes in the range 4–300 K show the existence of a dominant antiferromagnetic interaction with −J values greater than 300 cm−1. Therma…
High oxidation state aqueous organometallics: synthesis and structure of a dinuclear oxo(pentamethylcyclopentadienyl)acetato complex of molybdenum(IV…
2003
International audience; The zinc reduction of Cp*2Mo2O5 in a MeOH–H2O mixture in the presence of acetic acid affords the diamagnetic dinuclear compound [Cp*MoO(O2CCH3)]2. An X-ray structural investigation reveals a novel dioxo- and diacetato-bridged structure, with a relatively strong metal–metal bond [2.5524(3) Å]. The compound exhibits a reversible one-electron oxidation process in the cyclic voltammogram. A comparison with other related structures reveals the effect of the electric charge on the mononuclear or dinuclear structural choice.Zinc reduction of Cp*2Mo2O5 in water–methanol in the presence of acetic acid affords compound Cp*2Mo2O2(O2CCH3)2, whose dinuclar tetrabridged structure …
A New Co-Ni-Heterometallic Butterfly Complex Obtained via a Novel Synthesis Approach
2011
Abstract. The heterometallic complex [Co2Ni2(OH)2(O2CtBu)6(HOEt)6]·2EtOH (1) with a so called butterfly structural motif was prepared by reaction of the homometallic precursor complexes [Co2(H2O)(O2CtBu)4(HO2CtBu)4] and [Ni2(H2O)(O2CtBu)4(HO2CtBu)4] in an one to one ratio under elevate temperature. Complex 1 was characterized by single-crystal X-ray diffraction, atomic absorption spectroscopy, elemental analyses, IR spectroscopy, and mass spectrometry. The magnetic data show an overall antiferromagnetic behavior, which can be explained with three different coupling constants, resulting in a paramagnetic ground state.
Does cyclic GMP mediate the negative inotropic effect of acetylcholine in the heart?
1977
DURING vagal stimulation the pacemaker activity of the heart is diminished. The reduction in heart rate is due to a release of acetylcholine (ACh) from the parasympathetic nerve terminals that increases the permeability of the myocardial cell membrane for potassium ions (for review see ref. 1). This is accompanied by a shortening of the action potential duration in atrial muscle and a diminished calcium uptake2, which in turn results in a negative inotropic effect. Voltage clamp experiments in mammalian atrial muscle have shown that with higher concentrations of ACh not only is the potassium current augmented but also the slow inward current of calcium is reduced3. It is not clear how the c…
Hybrid magnetic materials formed by ferritin intercalated into a layered double hydroxide
2008
A hybrid magnetic material formed by ferritin intercalated into a layered double hydroxide (LDH) of Mg and Al (Mg/Al molar ratio 2) is prepared and characterized through powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, electron probe microanalysis (EPMA) and high resolution transmission electron microscopy (HRTEM). One observes an enhancement in the thermal stability of the ferritin molecules when they are inserted in the layered material. Magnetic measurements of the hybrid material exhibit the typical superparamagnetic behaviour of the ferritin molecule. On the other hand, the intercalation of ferritin into the LDH guarante…
Cytotoxic effect of As(III) in Caco-2 cells and evaluation of its human intestinal permeability.
2005
Inorganic arsenic has been classified as a carcinogen for humans (Group I). However, its transit across the human intestinal epithelium has not been characterized. Using Caco-2 cells, the thiol-redox balance and apparent permeability coefficients (P(app)) for As(III) in the apical to basolateral (AP-BL) and basolateral to apical (BL-AP) direction were evaluated. After As(III) exposure, GSH-induced synthesis was observed, increasing the GSH/GSSG ratio by elevating the As(III) concentration. The AP-BL permeabilities decreased as the As(III) concentrations increased, indicating the existence of a mediated transport mechanism. The (BL-AP)/(AP-BL) permeability ratios were higher than unity, sugg…
Caco‐2 versus Caco‐2/HT29‐MTX Co‐cultured Cell Lines: Permeabilities Via Diffusion, Inside‐ and Outside‐Directed Carrier‐Mediated Transport
2000
Abstract Purpose The objective of this study was a systematic characterization and evaluation of cell culture models based on mixtures of Caco‐2/HT29‐MTX co‐cultures for their use in screening for drug absorption and intestinal permeability in comparison to the properties of the respective mono‐cultures. Methods Co‐cultures of Caco‐2 cells (absorptive‐type) and HT29‐MTX cells (goblet‐type) were set up. Three different co‐cultures (initial seeding ratios Caco‐2/HT29‐MTX: 90/10, 70/30, and 50/50) were grown on permeable filter supports, and monolayers were used for permeability studies with model compounds for paracellular absorption (atenolol, furosemide, H334/75, mannitol, terbutaline), tra…
Inverse Scattering Solutions with Applications to Electromagnetic Signal Processing
2009
When a signal is recorded that has been physically generated by some scattering process (the interaction of electromagnetic, acoustic or elastic waves with inhomogeneous materials, for example), the ‘standard model’ for the signal (i.e. information content convolved with a characteristic Impulse Response Function) is usually based on a single scattering approximation. An additive noise term is introduced into the model to take into account a range of non-deterministic factors including multiple scattering that, along with electronic noise and other background noise sources, is assumed to be relatively weak. Thus, the standard model is based on a ‘weak field condition’ and the inverse scatte…
Intercalation of [M(ox)3]3− (M=Cr, Rh) complexes into NiIIFeIII-LDH
2010
Abstract Layered Double Hydroxides (LDH) containing paramagnetic NiII and FeIII ions in the hydroxide layers and chromium or rhodium oxalate complexes at the interlayer space were prepared by ion exchange from a NiFe-LDH precursor with sebacate anions between the hydroxide layers. The precursor was synthesized by coprecipitation at controlled pH in order to avoid the formation of solid phases different from LDH. Magnetic studies demonstrated that both LDHs, NiFe–Cr(ox)3 and NiFe–Rh(ox)3, exhibited a behaviour similar to the precursor. Nevertheless, the substitution of intercalated sebacate anions with oxalate complexes compresses the LDH basal spacing, increasing the intensity of dipolar in…