Electronic structure of ferromagnetic semiconductor Ga1-xMnxAs probed by sub-gap magneto-optical spectroscopy

We employ Faraday and Kerr effect spectroscopy in the infrared range to investigate the electronic structure of Ga1-xMnxAs near the Fermi energy. The band structure of this archetypical dilute-moment ferromagnetic semiconductor has been a matter of controversy, fueled partly by previous measurements of the unpolarized infrared absorption and their phenomenological impurity-band interpretation. The infrared magneto-optical effects we study arise directly from the spin-splitting of the carrier bands and their chiral asymmetry due to spin-orbit coupling. Unlike the unpolarized absorption, they are intimately related to ferromagnetism and their interpretation is much more microscopically constrained in terms of the orbital character of the relevant band states. We show that the conventional theory of the disordered valence band with dominant As p-orbital character and coupled by kinetic-exchange to Mn local moments accounts semi-quantitatively for the overall characteristics of the measured infrared magneto-optical spectra.Comment: 4 pages 3 figure

Electronic structure of ferromagnetic semiconductor Ga1-xMnxAs probed by sub-gap magneto-optical spectroscopyElectronic

We employ Faraday and Kerr effect spectroscopy in the infrared range to investigate the electronicstructure ofGa1 xMnxAsnear the Fermi energy. The band structure of this archetypical dilute-momentferromagnetic semiconductor has been a matter of controversy, fueled partly by previous measurements ofthe unpolarized infrared absorption and their phenomenological impurity-band interpretation. Unlike theunpolarized absorption, the infrared magneto-optical effects we study are intimately related to ferromag-netism, and their interpretation is much more microscopically constrained in terms of the orbital characterof the relevant band states. We show that the conventional theory of the disordered valence band with anantiferromatnetic exchange term accounts semiquantitatively for the overall characteristics of themeasured infrared magneto-optical spectra

The Sicilian network of biological therapy in inflammatory bowel disease: preliminary data on efficacy .

Background and aim: The monitoring of appropriateness and costs of biological therapy in Inflammatory bowel disease (IBD) is a relevant need. We aimed to evaluate appropriateness, efficacy and safety of biological therapy in IBD in Sicily through a web based network of prescribing centers. Material and methods: The Sicilian network for the monitoring of biological therapy in IBD is composed by a super Hub coordinator center and five Hub plus ten Spoke centers. From January 2013 all IBD patients starting a biological agent (incident cases) or already on treatment (prevalent cases) were entered in a web based software. Herein we report data on remission and response after twelve weeks of biological therapy, and side effects until the end of follow-up of incident cases. Results: From January 2013 to June 2016, 1475 patients were included. Complete data were available in 1338 cases (983 with Crohn’s disease [CD], 345 with ulcerative colitis [UC], and 10 with unclassified colitis). Incident cases were 956 (673 CD, 274 UC, and 9 unclassified colitis). Considering that 12% of patients experienced more than one line of therapy, a total of 1098 treatments were reported. Adalimumab was used in 543 CD patients, in 69 UC patients, and in 4 with unclassified colitis. Infliximab was prescribed in 221 CD patients (64 biosimilars), in 226 UC patients (41 biosimilars), and in 5 patients with unclassified colitis. Golimumab was prebscribed in 29 UC patients, and in 1 patient with unclassified colitis. After twelve weeks, the rate of response with Adalimumab was 46% and the rate of remission was 38% in CD, while the rate of response with Infliximab originator was 48% and the rate of remission 42% (biosimilars: 37% and 50%, respectively). In UC the rate of response with Adalimumab was 46% and the rate of remission was 38%, the rate of response with Infliximab was 41% and the rate of remission 45% (biosimilars: 25% and 64%, respectively), while the rate of response with Golimumab was 47% and the rate of remission was 27%. Overall, the rate of side effects was 17% (9.2% with Adalimumab, 20% with Infliximab originator, 15% with biosimilars, and 17% with Golimumab). Conclusions: In one of the largest series of IBD patients on biological therapy reported to date, the rates of remission and response after twelve weeks were comparable to data from literature, and similar between the different biologics. Efficacy and safety of biosimilars were analogous to those reported for infliximab originator

Carrier-mediated ferromagnetic ordering in Mn ion-implanted p+GaAs:C

Highly p-type GaAs:C was ion-implanted with Mn at differing doses to produce Mn concentrations in the 1 - 5 at.% range. In comparison to LT-GaAs and n+GaAs:Si samples implanted under the same conditions, transport and magnetic properties show marked differences. Transport measurements show anomalies, consistent with observed magnetic properties and with epi- LT-(Ga,Mn)As, as well as the extraordinary Hall Effect up to the observed magnetic ordering temperature (T_C). Mn ion-implanted p+GaAs:C with as-grown carrier concentrations > 10^20 cm^-3 show remanent magnetization up to 280 K

Import of cytochrome c into mitochondria

The import of cytochrome c into mitochondria can be resolved into a number of discrete steps. Here we report on the covalent attachment of heme to apocytochrome c by the enzyme cytochrome c heme lyase in mitochondria from Neurospora crassa. A new method was developed to measure directly the linkage of heme to apocytochrome c. This method is independent of conformational changes in the protein accompanying heme attachment. Tryptic peptides of [35S]cysteine-labelled apocytochrome c, and of enzymatically formed holocytochrome c, were resolved by reverse-phase HPLC. The cysteine-containing peptide to which heme was attached eluted later than the corresponding peptide from apocytochrome c and could be quantified by counting 35S radioactivity as a measure of holocytochrome c formation. Using this procedure, the covalent attachment of heme to apocytochrome c, which is dependent on the enzyme cytochrome c heme lyase, could be measured. Activity required heme (as hemin) and could be reversibly inhibited by the analogue deuterohemin. Holocytochrome c formation was stimulated 5–10-fold by NADH > NADPH > glutathione and was independent of a potential across the inner mitochondrial membrane. NADH was not required for the binding of apocytochrome c to mitochondria and was not involved in the reduction of the cysteine thiols prior to heme attachment. Holocytochrome c formation was also dependent on a cytosolic factor that was necessary for the heme attaching step of cytochrome c import. The factor was a heat-stable, protease-insensitive, low-molecular-mass component of unknown function. Cytochrome c heme lyase appeared to be a soluble protein located in the mitochondrial intermembrane space and was distinct from the previously identified apocytochrome c binding protein having a similar location. A model is presented in which the covalent attachment of heme by cytochrome c heme lyase also plays an essential role in the import pathway of cytochrome c

Defect states and their electric field-enhanced electron thermal emission in heavily Zr-doped beta-Ga2O3 crystals

Performing deep level transient spectroscopy (DLTS) on Schottky diodes, we investigated defect levels below the conduction band minima (Ec) in Czochralski (CZ) grown unintentionally-doped (UID) and vertical gradient freeze (VGF)-grown Zr-doped beta-Ga2O3 crystals. In UID crystals with an electron concentration of 10^17 cm-3, we observe levels at 0.18 eV and 0.46 eV in addition to the previously reported 0.86 (E2) and 1.03 eV (E3) levels. For 10^18 cm-3 Zr-doped Ga2O3, signatures at 0.30 eV (E15) and 0.71 eV (E16) are present. For the highest Zr doping of 5*10^18 cm-3, we observe only one signature at 0.59 eV. Electric field-enhanced emission rates are demonstrated via increasing the reverse bias during measurement. The 0.86 eV signature in the UID sample displays phonon-assisted tunneling enhanced thermal emission and is consistent with the widely reported E2 (FeGa) defect. The 0.71 eV (E16) signature in the lower-Zr-doped crystal also exhibits phonon-assisted tunneling emission enhancement. Taking into account that the high doping in the Zr-doped diodes also increases the electric field, we propose that the 0.59 eV signature in the highest Zr-doped sample likely corresponds to the 0.71 eV signature in lower-doped samples. Our analysis highlights the importance of testing for and reporting on field-enhanced emission especially the electric field present during DLTS and other characterization experiments on beta-Ga2O3 along with the standard emission energy, cross-section, and lambda-corrected trap density. This is important because of the intended use of beta-Ga2O3 in high-field devices and the many orders of magnitude of possible doping.Comment: 18 pages, 3 figure