A quantitative difference in the immune response to sheep red cells between rat strains

Résumé Des rats appartenant à plusieurs souches ont été immunisés par injection i.p. de 2×10⁸ globules rouges de mouton. La mesure du titre des haemolysines réalisée 6 jours plus tard montre des différences quantitatives selon les souches. Une réponse importante n'a pu être décelée que pour 3 d'entre elles (August, OFA et Wistar R).     

Giant spin Seebeck effect in a non-magnetic material

The spin Seebeck effect is observed when a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material, where it gets converted into a measurable voltage. It has been previously observed with a magnitude of microvolts per kelvin in magnetically ordered materials, ferromagnetic metals, semiconductors and insulators. Here we describe a signal in a non-magnetic semiconductor (InSb) that has the hallmarks of being produced by the spin Seebeck effect, but is three orders of magnitude larger (millivolts per kelvin). We refer to the phenomenon that produces it as the giant spin Seebeck effect. Quantizing magnetic fields spin-polarize conduction electrons in semiconductors by means of Zeeman splitting, which spin-orbit coupling amplifies by a factor of ～25 in InSb. We propose that the giant spin Seebeck effect is mediated by phonon-electron drag, which changes the electrons' momentum and directly modifies the spin-splitting energy through spin-orbit interactions. Owing to the simultaneously strong phonon-electron drag and spin-orbit coupling in InSb, the magnitude of the giant spin Seebeck voltage is comparable to the largest known classical thermopower values.     

Antilocalization sensing of interactions between two-dimensional electrons and surface species

We apply antilocalization measurements to experimentally study the interactions and exchange between InAs surface accumulation electrons and local magnetic moments of the rare earth ions Sm3?,Gd3?,Ho3?,and Dy3?,of the transition metal ions Ni2?,Co2?,and Fe3?,and of Fe3O4nanoparticles and Fe3?-phthalocyanine deposited on the surface.The influence of the deposited species on the surface electrons is observed through the changes in the spin–orbit scattering and magnetic spin-flip scattering rates,which carry information about magnetic interactions.Experiments indicate a temperature-dependent magnetic spin-flip scattering for Ho3?,Dy3?,Ni2?,and Co2?.Concerning the spin–orbit scattering rate,we observe an increase,except for the cases of Ni2?,Fe3?,Fe3O4nanoparticles and Fe3?-phthalocyanine.We also observe an increase in SO scattering in another system where we study the interactions of Au nanoparticles and ferromagnetic Co0.6Fe0.4nanopillars and an In0.53Ga0.47As quantum well.Experimental results are analyzed and compared to theoretical models.Our method provides a controlled way to probe the quantum properties of two-dimensional electron systems,either on the surface of InAs or in a quantum well.     

Specific and non-specific immunoglobulin synthesis in germfree mice immunized with ferritin by different routes

Résumé Après injection de ferritine de cheval, des souris C₂H axéniques développèrent des anticorps circulants ainsi que des immunoglobulines sans affinité pour l'antigène dans chacune des classes: IgA, IgM, IgG₁, et IgG₂. Après immunisation orale, la réponse spécifique fut exclusivement du type IgA, et la réponse non-spécifique principalement du type IgG₂ et IgA.

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Belgian American Educational Foundation Fellow.

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Staff Member of the Biology Division of Euratom, Euratom Publication No. 486.

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The Rega Institute for Medical Research, Louvain.     

Etude immuno-électrophorétique de l'uromucoïde

Summary Concentrated normal urines were investigated by an immuno-electrophoretic technique using specific antiserum directed against uromucoid (=Tamm andHorsfall's urinary mucoprotein).A single precipitation line was observed, which, however, presented two distinct maxima. The faster antigen appeared to be situated between albumin and ₁-globulin, while the slower antigen seemed to be ana ₂-globulin. Both antigens were immunologically identical with uromucoid, although the latter had been eliminated by salt precipitation from the urines used in this experiment.The above findings can best be explained by assuming the occurrence of a polymer series of uromucoid, of which the lower members would be soluble in 0.58M NaCl, while the higher terms would representTamm andHorsfall's mucoproteinsensu stricto. It is suggested that cylindroids and nubecula represent visible forms of uromucoid.