Quantum-chemical simulation and experimental study of some magnetic nanoparticles stabilized in fluid suspensions by using organic coating

Abstract

The biomedical applications of magnetic nanoparticles require the surface modification with organic, hydrophilic molecules, able to ensure the stability of the resulted colloidal suspensions. We present the quantum mechanical approach of two molecules developing stable interfaces with magnetic Co_0.5Fe_2.5O₄ nanoparticles. Sodium oleate, and citric acid, ensuring steric and respectively electrostatic stabilization are comparatively analyzed. The roles of dipole moment and frontier orbitals energies were emphasized to better understanding of some interface phenomena for the optimization of magnetic nanoparticle suspension preparation. Further, practical yielding of colloidal Co_0.5Fe_2.5O₄ nanoparticles by coating with sodium oleate and respectively with citric acid is discussed.     

Determination of propagation constants in a Ti:LiNbO3 optical waveguide by using finite element and variational methods

The finite element and variational methods are used to determine the propagation constants in a titanium indiffused lithium niobate waveguide with the reconstructed refractive index profile (in depth) from the near field measurements. A subsequent second diffusion of magnesium affects the shape of the calculated electric field and we have defined an effective depth of the profile.     

A desingularization theorem of Néron type

Summary LetA→A′ be a regular morphism between two noetherian rings. Then for everyA-algebra of finite typeB, everyA-morphism fromB toA′ can be factorised through aB-algebra of finite typeB′ which is standard (smooth) overA and which is ?as smooth as possible? overB (i.e. except above the singular locus ofB overA). This result is a positive answer to one conjecture due to M. Artin.

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Riassunto SiaA→A′ un omomorfismo regolare di anelli noetheriani. Si dimostra che per ogniA-algebraB di tipo finito, ogniA-omomorfismoB→A′ si può fattorizzare mediante unaB-algebraB′ di tipo finito che è liscia suA ed è ?la più liscia posibile? suB (più precisamente liscia suB meno il luogo singolare diB suA). Questo risultato è una risposta affermativa a una congettura di M. Artin.

     

Relative population of the oblate and prolate structures in187Au

The population of the oblate and the prolate structures in¹⁸⁷Au has been studied using the “Château de Cristal” set-up through the¹⁷²Yb(¹⁹F, 4n) reaction at 90, 95 and 100 MeV beam energy. γ — γ, γ-Fold and γ -Sum energy coincidence measurements were performed, γ-ray intensity measurements showed that as the beam energy increases the prolate system is less populated than the oblate one. Fold and Sum-energy associated with oblate and prolate structures showed a different behaviour with increasing beam energy. Two mechanisms are suggested to explain these results.     

Current-influenced voltage noise in bulk polycrystalline high-Tc superconductors

The 1/f voltage noise in bulk polycrystalline high-temperature superconductors (HTSC) under bias current and magnetic field has its origin in the noise current-dependence of the grain boundary junctions (GBJs), due in turn to the correlated effects of junction critical current and normal resistance fluctuations. The analogy between the results obtained by varying the bias current through the specimen and those performed with temperature as variable is evidenced. The noise maxima obtained in both sets of measurements turn out to be caused by the junction critical current fluctuations, which dominate when the currents flowing through the GBJs are close to the Josephson critical current. The anti-phase correlation between the normal resistance and the critical current fluctuations is responsible for the monotonical decrease of the noise at constant bias current, with the temperature exceeding the value corresponding to the noise maximum. In contrast, varying the bias current at fixed temperature, the voltage noise exhibits a local minimum followed by an increasing tendency after passing through the maximum.     

HPTLC and GC-MS for Separation and Identification of Eugenol in Plants

JPC – Journal of Planar Chromatography – Modern TLC - Samples of clove, nutmeg, and cinnamon have been extracted by maceration with ethanol for 24 h and with aqueous ethanol 48 h....     

Characterization of ceramic ion-selective membrane-electrodes-I The Ag(2)S electrode

The behaviour of a new type of electrode, made from ceramic Ag(2)S, has been investigated. The electrode response is Nernstian for Ag(+) over the range 10(-6)-2M and for Hg(2+) in the concentration range 10(-6)-10(-2)M, both at constant ionic strength (0.1M). The electrode is Ag(+)-selective, with maximum interference from Hg(2+). It can be used for acid-base potentiometric titration and for potentiometric Ag(+) and Hg(2+) precipitation titrations.     

Magnetic moment measurements in67Ga

The ratio of the g-factors of the 5/2^–, 0.359 MeV and 15/2⁺, 3.578 MeV levels in⁶⁷Ga has been found to be (1±0.32)(0.40±0.09) by means of the recoil-into-gas (helium) integral perturbed angular correlation technique. The studied states were populated by the reaction⁵⁷Fe(¹²C,pn)⁶⁷Ga at E_C=40 MeV.