Rechnerische Bestimmung der lonenbeweglichkeit in Ziegelstein unter Zuhilfenahme von Ergebnissen aus nichtstationären Diffusionsversuchen

Ion concentration profiles in sandwich-brick specimens have been determined experimentally at different degrees of water saturation. Based on the experimental data, ion diffusion coefficients were determined by inverse analysis. The diffusion equation served as a basis for an optimization technique. It has been shown that the ion diffusivity in bricks decreases markedly as the moisture content decreases. The interface between two adjacent bricks slows down the ion migration at low water content in particular. It is planed to investigate the interface between mortar and bricks in further experimental and numerical studie

Spin fluctuations probed by NMR in paramagnetic spinel LiV2_2O4_4: a self-consistent renormalization theory

Low frequency spin fluctuation dynamics in paramagnetic spinel LiV$_2$O$_4$, a rare 3$d$-electron heavy fermion system, is investigated. A parametrized self-consistent renormalization (SCR) theory of the dominant AFM spin fluctuations is developed and applied to describe temperature and pressure dependences of the low-$T$ nuclear spin-lattice relaxation rate $1/T_1$ in this material. The experimental data for $1/T_1$ available down to $\sim 1$K are well reproduced by the SCR theory, showing the development of AFM spin fluctuations as the paramagnetic metal approaches a magnetic instability under the applied pressure. The low-$T$ upturn of $1/T_1T$ detected below 0.6 K under the highest applied pressure of 4.74 GPa is explained as the nuclear spin relaxation effect due to the spin freezing of magnetic defects unavoidably present in the measured sample of LiV$_2$O$_4$.Comment: 11 pages, 2 figure

Heavy-Fermions in LiV2O4: Kondo-Compensation vs. Spin-Liquid Behavior?

7Li NMR measurements were performed in the metallic spinel LiV2O4. The temperature dependencies of the line width, the Knight shift and the spin-lattice relaxation rate were investigated in the temperature range 30 mK < T < 280 K. For temperatures T < 1 K we observe a spin-lattice relaxation rate which slows down exponentially. The NMR results can be explained by a spin-liquid behavior and the opening of a spin gap of the order 0.6 K

Staggered magnetism in LiV2_2O4_4 at low temperatures probed by the muon Knight shift

We report on the muon Knight shift measurement in single crystals of LiV2O4. Contrary to what is anticipated for the heavy-fermion state based on the Kondo mechanism, the presence of inhomogeneous local magnetic moments is demonstrated by the broad distribution of the Knight shift at temperatures well below the presumed "Kondo temperature" ($T^*\simeq 30$ K). Moreover, a significant fraction ($\simeq10$ %) of the specimen gives rise to a second component which is virtually non-magnetic. These observations strongly suggest that the anomalous properties of LiV2O4 originates from frustration of local magnetic moments.Comment: 11 pages, 5 figures, sbmitted to J. Phys.: Cond. Mat

Fluorescence Correlation Spectroscopy Monitors the Fate of Degradable Nanocarriers in the Blood Stream

[Image: see text] The use of nanoparticles as carriers to deliver pharmacologically active compounds to specific parts of the body via the bloodstream is a promising therapeutic approach for the effective treatment of various diseases. To reach their target sites, nanocarriers (NCs) need to circulate in the bloodstream for prolonged periods without aggregation, degradation, or cargo loss. However, it is very difficult to identify and monitor small-sized NCs and their cargo in the dense and highly complex blood environment. Here, we present a new fluorescence correlation spectroscopy-based method that allows the precise characterization of fluorescently labeled NCs in samples of less than 50 μL of whole blood. The NC size, concentration, and loading efficiency can be measured to evaluate circulation times, stability, or premature drug release. We apply the new method to follow the fate of pH-degradable fluorescent cargo-loaded nanogels in the blood of live mice for periods of up to 72 h

Hierarchical self-entangled carbon nanotube tube networks

R.A. gratefully acknowledges partial project funding by the Deutsche Forschungsgemeinschaft (DFG) contract AD183-17-1 as well as in the framework of the GRK 2154 and FOR 1616, and support from the European Comission in the framework of the Graphene FET Flagship. N.M.P. is supported by the European Research Council ERC PoC 2015 SILKENE No. 693670 and by the European Commission H2020 under the Graphene FET Flagship (WP14 “Polymer Composites” No. 696656) and under the FET proactive (“Neurofibres” No. 732344). S.S. acknowledges financial support from SILKENE. This work was partly supported by the Leverhulme Trust project CARBTRIB to S.N.G. We acknowledge financial support by Land Schleswig Holstein within the funding program “Open Access Publikationsfonds”. Furthermore, we thank Heather Cavers for proofreading and correcting the manuscript

High-field magnetization of the 3d heavy-fermion system LiV2_2O4−d_{4-d} (d = 0, 0.08)

Metamagnetic behavior has been observed in LiV2O4 powder sample around 38 T at 4.2 K. On the other hand, magnetization for oxygen deficient LiV2O3.92 shows no indication of metamagnetism up to 40 T, and shows substantially reduced magnetic moment compared to that of LiV2O4. These results suggest that ferromagnetic interaction is strongly enhanced by magnetic fields in LiV2O4, whereas antiferromagnetic interaction is dominant in LiV2O3.92.Comment: 9 pages, 3 figures, to be published in J. Phys.: Condens. Matte

Stability of a metallic state in the two-orbital Hubbard model

Electron correlations in the two-orbital Hubbard model at half-filling are investigated by combining dynamical mean field theory with the exact diagonalization method. We systematically study how the interplay of the intra- and inter-band Coulomb interactions, together with the Hund coupling, affects the metal-insulator transition. It is found that if the intra- and inter-band Coulomb interactions are nearly equal, the Fermi-liquid state is stabilized due to orbital fluctuations up to fairly large interactions, while the system is immediately driven to the Mott insulating phase away from this condition. The effects of the isotropic and anisotropic Hund coupling are also addressed.Comment: 7 pages, 9 figure

Metal-insulator transition in the two-orbital Hubbard model at fractional band fillings: Self-energy functional approach

We investigate the infinite-dimensional two-orbital Hubbard model at arbitrary band fillings. By means of the self-energy functional approach, we discuss the stability of the metallic state in the systems with same and different bandwidths. It is found that the Mott insulating phases are realized at commensurate band fillings. Furthermore, it is clarified that the orbital selective Mott phase with one orbital localized and the other itinerant is stabilized even at fractional band fillings in the system with different bandwidths.Comment: 7 pages, 10 figure