New adjuvant design using layered double hydroxide for production of polyclonal antibodies in radioimmunoassay techniques

Various adjuvants have been used to enhance the immune response against specific antigens. So the objective of this work describes the immune stimulating activity of layered double hydroxide (LDH) particles incorporate with mineral oil as a new formulation of adjuvant as compared to known Freund’s adjuvant for production of alpha-fetoprotein polyclonal antibody (anti-AFP) for estimation of alpha fetoprotein (AFP) in human serum by radioimmunoassay technique. In this concern, the study comprised two groups of white New Zealand rabbits, 2?2.5 kg body weight and each group comprised three rabbits. The first group vaccinated with AFP antigen emulsified with Freund’s adjuvant and the second group vaccinated with AFP antigen emulsified with LDH formulation. The obtained data show that the highest displacement using LDH adjuvant reached (74.2, 61.7 and 66.5 %) while the corresponding values with Freund’s adjuvant recorded (64.8, 60.3 and 54.6 %) which indicates that the use of LDH adjuvant as a cellular vehicle is a more suitable choice. Also, the preparation of AFP tracer using lactoperoxidase oxidation method and its purification using gel chromatography on PD-10 column were carried out. Different factors affecting the optimization of the assay process were studied. Validation testes of the assay were carried out. The reproducibility as measured by the intra- and inter- assay variations is satisfactory. The recovery and dilution testes indicated accurate calibration and appropriate matrix. The present technique agreed well with the currently used commercial kit (Siemens, IRMA kit). In conclusion, the liquid phase double antibody RIA technique proved to be sensitive, specific, precis and accurate for routine laboratory use.     

Micellar catalysis by perfluorooctanoic acid

Rates of acidic hydrolysis of hexano-, octano-, and decanohydroxamic acids and of 4-bromophenylaceto- and phenylacetohydroxamic acids have been determined in aqueous perfluorooctanoic acid—a reactive counterion surfactant system. Typical micellar catalysis was observed for the hydrolyses of the n-alkyl hydroxamic acids but not for the arylacetohydroxamic acids. The Arrhenius activation energy for hydrolysis of octano-hydroxamic acid is smaller above the cmc of the surfactant than it is below the cmc.     

Structural, magnetic and electronic transport properties of MnxGe1−x/Ge(0 0 1) films grown by MBE at 350 °C

We report on the structural, magnetic and electronic transport properties of thin Mn_xGe_1−x films grown at 350 °C. Isolated Mn₅Ge₃ nanoclusters, about 100 nm in size, were formed at the top surface of the film, dominating the magnetic properties of the whole film. Electronic transport properties show Mn doping effect indicating the presence of substitutional Mn ions dispersed in the Ge host, contributing to the formation of a Mn_xGe_1−x diluted phase. Electrical behaviour indicates a saturation effect with the raise of the nominal Mn concentration in the film, above x ≅ 0.03.     

Effects of Magnet Size and Geometry on Magnetic Levitation Force

We obtain analytical relations for the levitation force as a function of dimensions of the superconductor-magnet system. The force has been calculated on the basis of the dipole-dipole interaction model. The effect of thickness of the superconductor on the levitation force is investigated. The results show that the influence of geometry and thickness of the magnet becomes significantly large at small levitation distances. Furthermore, approximating the permanent magnet as a point dipole results in an inaccurate estimation of the levitation force.     

Levitation and lateral forces between a point magnetic dipole and a superconducting sphere

The dipole–dipole interaction model is employed to investigate the angular dependence of the levitation and lateral forces acting on a small magnet in an anti-symmetric magnet/superconducting sphere system. Breaking the symmetry of the system enables us to study the lateral force which is important in the stability of the magnet above a superconducting sphere in the Meissner state. Under the assumption that the lateral displacement of the magnet is small compared to the physical dimensions of our proposed system, analytical expressions are obtained for the levitation and lateral forces as a function of the geometrical parameters of the superconductor as well as the height, the lateral displacement, and the orientation of the magnetic moment of the magnet. The dependence of the levitation force on the height of the levitating magnet is similar to that in the symmetric magnet/superconducting sphere system within the range of proposed lateral displacements. It is found that the levitation force is linearly dependent on the lateral displacement whereas the lateral force is independent of this displacement. A sinusoidal variation of both forces as a function of the polar and azimuthal angles specifying the orientation of the magnetic moment is observed. The relationship between the stability and the orientation of the magnetic moment is discussed for different orientations.