TY  - JOUR
A1  - Fiedler, Sebastian
A1  - El-Kareh, Lydia
A1  - Eremeev, Sergey V.
A1  - Tereshchenko, Oleg E.
A1  - Seibel, Christoph
A1  - Lutz, Peter
A1  - Kokh, Konstantin A.
A1  - Chulkov, Evgueni V.
A1  - Kuznetsova, Tatyana V.
A1  - Grebennikov, Vladimir I.
A1  - Bentmann, Hendrik
A1  - Bode, Matthias
A1  - Reinert, Friedrich
T1  - Defect and structural imperfection effects on the electronic properties of BiTeI surfaces
JF  - New Journal of Physics
N2  - The surface electronic structure of the narrow-gap seminconductor BiTeI exhibits a large Rashba-splitting which strongly depends on the surface termination. Here we report on a detailed investigation of the surface morphology and electronic properties of cleaved BiTeI single crystals by scanning tunneling microscopy, photoelectron spectroscopy (ARPES, XPS), electron diffraction (SPA-LEED) and density functional theory calculations. Our measurements confirm a previously reported coexistence of Te- and I-terminated surface areas originating from bulk stacking faults and find a characteristic length scale of ~100 nm for these areas. We show that the two terminations exhibit distinct types of atomic defects in the surface and subsurface layers. For electronic states resided on the I terminations we observe an energy shift depending on the time after cleavage. This aging effect is successfully mimicked by depositon of Cs adatoms found to accumulate on top of the I terminations. As shown theoretically on a microscopic scale, this preferential adsorbing behaviour results from considerably different energetics and surface diffusion lengths at the two terminations. Our investigations provide insight into the importance of structural imperfections as well as intrinsic and extrinsic defects on the electronic properties of BiTeI surfaces and their temporal stability.
KW  - electronic structure
KW  - spin–orbit coupling
KW  - surface morphology
KW  - semiconductor surfaces
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119467
SN  - 1367-2630
VL  - 16
IS  - 075013
ER  - 
TY  - JOUR
A1  - Veniaminova, Ekaterina
A1  - Cespuglio, Raymond
A1  - Chernukha, Irina
A1  - Schmitt-Boehrer, Angelika G.
A1  - Morozov, Sergey
A1  - Kalueff, Allan V.
A1  - Kuznetsova, Oxana
A1  - Anthony, Daniel C.
A1  - Lesch, Klaus-Peter
A1  - Strekalova, Tatyana
T1  - Metabolic, Molecular, and Behavioral Effects of Western Diet in Serotonin Transporter-Deficient Mice: Rescue by Heterozygosity?
JF  - Frontiers in Neuroscience
N2  - Reduced function of the serotonin transporter (SERT) is associated with increased susceptibility to anxiety and depression and with type-2 diabetes, which is especially true in older women. Preference for a “Western diet” (WD), enriched with saturated fat, cholesterol, and sugars, may aggravate these conditions. In previous studies, decreased glucose tolerance, central and peripheral inflammation, dyslipidemia, emotional, cognitive, and social abnormalities were reported in WD-fed young female mice. We investigated the metabolic, molecular, and behavioral changes associated with a 3-week-long dietary regime of either the WD or control diet in 12-month-old female mice with three different Sert genotypes: homozygous (Slc6a4) gene knockout (Sert\(^{−/−}\): KO), heterozygous (Sert\(^{+/−}\): HET), or wild-type mice (Sert\(^{+/+}\): WT). In the WT-WD and KO-WD groups, but not in HET-WD-fed mice, most of changes induced by the WD paralleled those found in the younger mice, including brain overexpression of inflammatory marker Toll-like receptor 4 (Tlr4) and impaired hippocampus-dependent performance in the marble test. However, the 12-month-old female mice became obese. Control diet KO mice exhibited impaired hippocampal-dependent behaviors, increased brain expression of the serotonin receptors Htr2c and Htr1b, as well as increased Tlr4 and mitochondrial regulator, peroxisome proliferator-activated receptor gamma-coactivator-1a (Ppargc1a). Paradoxically, these, and other changes, were reversed in KO-WD mutants, suggesting a complex interplay between Sert deficiency and metabolic factors as well as potential compensatory molecular mechanisms that might be disrupted by the WD exposure. Most, but not all, of the changes in gene expression in the brain and liver of KO mice were not exhibited by the HET mice fed with either diet. Some of the WD-induced changes were similar in the KO-WD and HET-WD-fed mice, but the latter displayed a “rescued” phenotype in terms of diet-induced abnormalities in glucose tolerance, neuroinflammation, and hippocampus-dependent performance. Thus, complete versus partial Sert inactivation in aged mice results in distinct metabolic, molecular, and behavioral consequences in response to the WD. Our findings show that Sert\(^{+/−}\) mice are resilient to certain environmental challenges and support the concept of heterosis as evolutionary adaptive mechanism.
KW  - Sert-deficient mice
KW  - Western diet
KW  - aging
KW  - glucose tolerance
KW  - Toll-like receptor 4 (TLR4)
KW  - serotonin receptors
KW  - obesity
KW  - heterosis
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-199813
SN  - 1662-453X
VL  - 14
ER  -