Nonmagnetic band gap at the Dirac point of the magnetic topological insulator Bi1 xMnx 2 Se3

Magnetic doping is expected to open a band gap at the Dirac point of topological insulators by breaking time-reversal symmetry and to enable novel topological phases. Epitaxial (Bi$_{1-x}$Mn$_{x}$)$_{2}$Se$_{3}$ is a prototypical magnetic topological insulator with a pronounced surface band gap of $\sim100$ meV. We show that this gap is neither due to ferromagnetic order in the bulk or at the surface nor to the local magnetic moment of the Mn, making the system unsuitable for realizing the novel phases. We further show that Mn doping does not affect the inverted bulk band gap and the system remains topologically nontrivial. We suggest that strong resonant scattering processes cause the gap at the Dirac point and support this by the observation of in-gap states using resonant photoemission. Our findings establish a novel mechanism for gap opening in topological surface states which challenges the currently known conditions for topological protection.Comment: 26 pages, 7 figure

Image force microscopy of molecular resonance: A microscope principle

We demonstrate a technique in microscopy which extends the domain of atomic force microscopy to optical spectroscopy at the nanometer scale. We show that molecular resonance of feature sizes down to the single molecular level can be detected and imaged purely by mechanical detection of the force gradient between the interaction of the optically driven molecular dipole and its mirror image in a platinum coated scanning probe tip. This microscopy and spectroscopy technique is extendable to frequencies ranging from radio to infrared and the ultraviolet

Milk yield measured by oxytocin plus hand milking and weigh-suckle-weigh methods in ewes originating from local crossbred in Turkey

Milk yield of ewes crossbred between Kivircik and Akkaraman (KAB(1)) and crossbred between Chios and Akkararnan breeds (CAB(1)) was evaluated during the whole lactation period. Two methods were compared: the weigh-suckle-weigh (WSW) and oxytocin plus hand milking (O plus HM) methods and the correlations between milk yield and growth of lambs were estimated. A total of 44 ewes and 52 lambs (36 single, 16 twins) were used. Measurements of milk yield for 6 hours were determined at 14-day intervals using the two methods (WSW and O plus HM). Overall mean milk yield estimates determined using O plus HM were significantly higher than those evaluated from the WSW method. CAB(1) ewes produced significantly more milk than the KAB(1) ewes. The milk yield differences between ewes suckling single and twin lambs were highly significant. The results showed that milk yield estimated by method of hand milking after oxytocin injection is higher than method of weigh-suckle-weigh during the entire lactation period, and that milk production of CAB(1) ewes is higher than that of KAB(1) ewes. The results also indicated that lamb live weight and milk production are highly correlated during early and middle lactation and these correlation coefficients decline as lactation progresses

Rydberg series of charge-transfer excitations: atomic chlorine and atomic hydrogen in rare gas crystals

Rydberg series obsd. in the excitation spectra of Cl and H atoms isolated in the rare gas (Rg) crystals Kr and Xe are assocd. with the charge transfer species Cl-Rg+ and H-Rg+. The progressions originate from hole states of Rg+ which converge to the top of the rare gas valence band in an analogous manner to the convergence of conventional exciton states to the bottom of the conduction band. A model based on the effective mass approxn. and a quantum defect concept predicted such progressions in Xe and Kr crystals and it is supported by the present results. In addn. to these data a review is given of similar results with other halogens and rare gases. [on SciFinder (R)

Chemogenomic Profiling of Human and Microbial FK506-Binding Proteins

FK506-binding proteins (FKBPs) are evolutionarily conserved proteins that display peptidyl-prolyl isomerase activities and act as coreceptors for immunosuppressants. Microbial macrophage-infectivity-potentiator (Mip)-type FKBPs can enhance infectivity. However, developing druglike ligands for FKBPs or Mips has proven difficult, and many FKBPs and Mips still lack biologically useful ligands. To explore the scope and potential of C5-substituted [4.3.1]-azabicyclic sulfonamides as a broadly applicable class of FKBP inhibitors, we developed a new synthesis method for the bicyclic core scaffold and used it to prepare an FKBP- and Mip-focused library. This allowed us to perform a systematic structure activityrelationship analysis across key human FKBPs and microbial Mips, yielding highly improved inhibitors for all the FKBPs studied. A cocrystal structure confirmed the molecular-binding mode of the core structure and explained the affinity gained as a result of the preferred substituents. The best FKBP and Mip ligands showed promising antimalarial, antileginonellal, and antichlamydial properties in cellular models of infectivity, suggesting that substituted [4.3.1]-aza-bicyclic sulfonamides could be a novel class of anti-infectives