Iron concentrations in neurons and glial cells with estimates on ferritin concentrations

BACKGROUND: Brain iron is an essential as well as a toxic redox active element. Physiological levels are not uniform among the different cell types. Besides the availability of quantitative methods, the knowledge about the brain iron lags behind. Thereby, disclosing the mechanisms of brain iron homeostasis helps to understand pathological iron-accumulations in diseased and aged brains. With our study we want to contribute closing the gap by providing quantitative data on the concentration and distribution of iron in neurons and glial cells in situ. Using a nuclear microprobe and scanning proton induced X-ray emission spectrometry we performed quantitative elemental imaging on rat brain sections to analyze the iron concentrations of neurons and glial cells. RESULTS: Neurons were analyzed in the neocortex, subiculum, substantia nigra and deep cerebellar nuclei revealing an iron level between [Formula: see text] and [Formula: see text]. The iron concentration of neocortical oligodendrocytes is fivefold higher, of microglia threefold higher and of astrocytes twofold higher compared to neurons. We also analyzed the distribution of subcellular iron concentrations in the cytoplasm, nucleus and nucleolus of neurons. The cytoplasm contains on average 73 of the total iron, the nucleolus-although a hot spot for iron-due to its small volume only 6 of total iron. Additionally, the iron level in subcellular fractions were measured revealing that the microsome fraction, which usually contains holo-ferritin, has the highest iron content. We also present an estimate of the cellular ferritin concentration calculating [Formula: see text] ferritin molecules per [Formula: see text] in rat neurons. CONCLUSION: Glial cells are the most iron-rich cells in the brain. Imbalances in iron homeostasis that lead to neurodegeneration may not only be originate from neurons but also from glial cells. It is feasible to estimate the ferritin concentration based on measured iron concentrations and a reasonable assumptions on iron load in the brain

Momentum-resolved evolution of the Kondo lattice into 'hidden-order' in URu2Si2

We study, using high-resolution angle-resolved photoemission spectroscopy, the evolution of the electronic structure in URu2Si2 at the Gamma, Z and X high-symmetry points from the high-temperature Kondo-screened regime to the low-temperature `hidden-order' (HO) state. At all temperatures and symmetry points, we find structures resulting from the interaction between heavy and light bands, related to the Kondo lattice formation. At the X point, we directly measure a hybridization gap of 11 meV already open at temperatures above the ordered phase. Strikingly, we find that while the HO induces pronounced changes at Gamma and Z, the hybridization gap at X does not change, indicating that the hidden-order parameter is anisotropic. Furthermore, at the Gamma and Z points, we observe the opening of a gap in momentum in the HO state, and show that the associated electronic structure results from the hybridization of a light electron band with the Kondo-lattice bands characterizing the paramagnetic state.Comment: Updated published version. Mansucript + Supplemental Material (8 pages, 9 figures). Submitted 16 September 201

Temperature dependence of the Kondo resonance and its satellites in CeCu_2Si_2

We present high-resolution photoemission spectroscopy studies on the Kondo resonance of the strongly-correlated Ce system CeCu$_2$Si$_2$. Exploiting the thermal broadening of the Fermi edge we analyze position, spectral weight, and temperature dependence of the low-energy 4f spectral features, whose major weight lies above the Fermi level $E_F$. We also present theoretical predictions based on the single-impurity Anderson model using an extended non-crossing approximation (NCA), including all spin-orbit and crystal field splittings of the 4f states. The excellent agreement between theory and experiment provides strong evidence that the spectral properties of CeCu$_2$Si$_2$ can be described by single-impurity Kondo physics down to $T \approx 5$ K.Comment: 4 pages, 3 figure

High-Resolution Photoemission Study of MgB2

We have performed high-resolution photoemission spectroscopy on MgB2 and observed opening of a superconducting gap with a narrow coherent peak. We found that the superconducting gap is s-like with the gap value of 4.5 meV at 15 K. The temperature dependence (15 - 40 K) of gap value follows well the BCS form, suggesting that 2Delta/kBTc at T=0 is about 3. No pseudogap behavior is observed in the normal state. The present results strongly suggest that MgB2 is categorized into a phonon-mediated BCS superconductor in the weak-coupling regime.Comment: 3 pages, 3 figures, accepted in Physical Review Letter

Systematics of electronic and magnetic properties in the transition metal doped Sb2_2Te3_3 quantum anomalous Hall platform

The quantum anomalous Hall effect (QAHE) has recently been reported to emerge in magnetically-doped topological insulators. Although its general phenomenology is well established, the microscopic origin is far from being properly understood and controlled. Here we report on a detailed and systematic investigation of transition-metal (TM)-doped Sb$_2$Te$_3$. By combining density functional theory (DFT) calculations with complementary experimental techniques, i.e., scanning tunneling microscopy (STM), resonant photoemission (resPES), and x-ray magnetic circular dichroism (XMCD), we provide a complete spectroscopic characterization of both electronic and magnetic properties. Our results reveal that the TM dopants not only affect the magnetic state of the host material, but also significantly alter the electronic structure by generating impurity-derived energy bands. Our findings demonstrate the existence of a delicate interplay between electronic and magnetic properties in TM-doped TIs. In particular, we find that the fate of the topological surface states critically depends on the specific character of the TM impurity: while V- and Fe-doped Sb$_2$Te$_3$ display resonant impurity states in the vicinity of the Dirac point, Cr and Mn impurities leave the energy gap unaffected. The single-ion magnetic anisotropy energy and easy axis, which control the magnetic gap opening and its stability, are also found to be strongly TM impurity-dependent and can vary from in-plane to out-of-plane depending on the impurity and its distance from the surface. Overall, our results provide general guidelines for the realization of a robust QAHE in TM-doped Sb$_2$Te$_3$ in the ferromagnetic state.Comment: 40 pages, 13 figure

Ion beam analysis of microcrystalline quartz artifacts from the Reed Mound Site, Delaware County, Oklahoma

Ion beam analysis (IBA) has been a powerful, non-destructive tool for archaeological research worldwide for over four decades, yet its full potential is seldom realized in North American archaeology. Herein the potential of particle induced X-ray emission spectrometry (PIXE) as a tool for future Ozarks chert provenance studies is evaluated based on its ability to facilitate (1) discrimination of Ozarks chert materials from different geological formations and (2) identification of discrete groups of artifacts from the same geological formation. In addition, PIXE was also used to evaluate the elemental heterogeneity of Ozarks chert materials. Thirty chert (microcrystalline quartz) artifacts were visually sorted and classified according to macroscopic features characteristic of certain chert resources from particular Ozarks geological formations. The elemental concentrations obtained from PIXE analysis underwent multivariate statistical analyses in order to gain insight from the data. The results indicate that PIXE could be a useful tool for assigning Ozarks chert materials to their respective geological formations, and possibly for determining regional or sub-regional provenance

Twisted exchange interaction between localized spins embedded in a one- or two-dimensional electron gas with Rashba spin-orbit coupling

We study theoretically the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in one- and two-dimensions in presence of a Rashba spin-orbit (SO) coupling. We show that rotation of the spin of conduction electrons due to SO coupling causes a twisted RKKY interaction between localized spins which consists of three different terms: Heisenberg, Dzyaloshinsky-Moriya, and Ising interactions. We also show that the effective spin Hamiltonian reduces to the usual RKKY interaction Hamiltonian in the twisted spin space where the spin quantization axis of one localized spin is rotated.Comment: 4pages, no figur

Dynamics of UF[6] Desublimation with the Influence of Tank Geometry for Various Coolant Temperature

Mathematical model of UF[6] desublimation in a vertical immersion tank is presented in the article. Results of calculations of the filling dynamics of the tanks with 1m3 volume at various coolant temperatures, with and without ellipticity of the end walls are given. It is shown that allowance for the ellipticity of the end walls of the tanks leads to a significant increase in the time of desublimation of UF[6]

Внедрение корпоративной системы управления проектами для реализации стратегических проектов компании

В целях реализации Восточной газовой программы ООО "Газпром трансгаз Томск" разработало Стратегию развития до 2020 г. и План организационно-технических мероприятий. Для успешного выполнения перспективных задач в организации формируется новая, современная система управления - корпоративная система управления проектами. Разработана методика внедрения корпоративной системы управления проектами, состав системы, определены ключевые участники и критические факторы успеха, выполнен расчет экономической эффективности проекта