397 research outputs found
Role of charge carriers for ferromagnetism in cobalt-doped rutile TiO2
Electric and magnetic properties of a high temperature ferromagnetic oxide
semiconductor, cobalt-doped rutile TiO2, are summarized. The cobalt-doped
rutile TiO2 epitaxial thin films with different electron densities and cobalt
contents were grown on r-sapphire substrates with laser molecular beam epitaxy.
Results of magnetization, magnetic circular dichroism, and anomalous Hall
effect measurements were examined for samples with systematically varied
electron densities and cobalt contents. The samples with high electron
densities and cobalt contents show the high temperature ferromagnetism,
suggesting that charge carriers induce the ferromagnetism.Comment: 14 pages, 12 figure
Electrical transport and optical studies of ferromagnetic Cobalt doped ZnO nanoparticles exhibiting a metal-insulator transition
The observed correlation of oxygen vacancies and room temperature
ferromagnetic ordering in Co doped ZnO1-o nanoparticles reported earlier (Naeem
et al Nanotechnology 17, 2675-2680) has been further explored by transport and
optical measurements. In these particles room temperature ferromagnetic
ordering had been observed to occur only after annealing in forming gas. In the
current work the optical properties have been studied by diffuse reflection
spectroscopy in the UV-Vis region and the band gap of the Co doped compositions
has been found to decrease with Co addition. Reflections minima are observed at
the energies characteristic of Co+2 d-d (tethrahedral symmetry) crystal field
transitions, further establishing the presence of Co in substitutional sites.
Electrical transport measurements on palletized samples of the nanoparticles
show that the effect of a forming gas is to strongly decrease the resistivity
with increasing Co concentration. For the air annealed and non-ferromagnetic
samples the variation in the resistivity as a function of Co content are
opposite to those observed in the particles prepared in forming gas. The
ferromagnetic samples exhibit an apparent change from insulator to metal with
increasing temperatures for T>380K and this change becomes more pronounced with
increasing Co content. The magnetic and resistive behaviors are correlated by
considering the model by Calderon et al [M. J. Calderon and S. D. Sarma, Annals
of Physics 2007 (Accepted doi: 10.1016/j.aop.2007.01.010] where the
ferromagnetism changes from being mediated by polarons in the low temperature
insulating region to being mediated by the carriers released from the weakly
bound states in the higher temperature metallic region.Comment: 7 pages, 6 figure
Bulk and Surface Magnetization of Co atoms in Rutile Ti_[1-x]Co_xO_[2-delta] Thin Films Revealed by X-Ray Magnetic Circular Dichroism
We have studied magnetism in Ti_[1-x]Co_xO_[2-\delta] thin films with various
x and \delta by soft x-ray magnetic circular dichroism (XMCD) measurements at
the Co L_[2,3] absorption edges. The estimated ferromagnetic moment by XMCD was
0.15-0.24 \mu\beta/Co in the surface, while in the bulk it was 0.82-2.25
\mu\beta/Co, which is in the same range as the saturation magnetization of
1.0-1.5 \mu\beta/Co. Theseresults suggest that the intrinsic origin of the
erromagnetism. The smaller moment of Co atom at surface is an indication of a
magnetically dead layer of a few nm thick at the surface of the thin films.Comment: This Paper is accepted in J. of Phys: Conds. Matte
Ab initio study of magnetism at the TiO2/LaAlO3 interface
In this paper we study the possible relation between the electronic and
magnetic structure of the TiO2/LaAlO3 interface and the unexpected magnetism
found in undoped TiO2 films grown on LaAlO. We concentrate on the role
played by structural relaxation and interfacial oxygen vacancies.
LaAlO3 has a layered structure along the (001) direction with alternating LaO
and AlO2 planes, with nominal charges of +1 and -1, respectively. As a
consequence of that, an oxygen deficient TiO2 film with anatase structure will
grow preferently on the AlO2 surface layer. We have therefore performed
ab-initio calculations for superlattices with TiO2/AlO2 interfaces with
interfacial oxygen vacancies. Our main results are that vacancies lead to a
change in the valence state of neighbour Ti atoms but not necessarily to a
magnetic solution and that the appearance of magnetism depends also on
structural details, such as second neighbor positions. These results are
obtained using both the LSDA and LSDA+U approximations.Comment: Accepted for publication in Journal of Materials Scienc
Neuroretinal hypoxic signaling in a new preclinical murine model for proliferative diabetic retinopathy
Diabetic retinopathy (DR) affects approximately one-third of diabetic patients and, if left untreated, progresses to proliferative DR (PDR) with associated vitreous hemorrhage, retinal detachment, iris neovascularization, glaucoma and irreversible blindness. In vitreous samples of human patients with PDR, we found elevated levels of hypoxia inducible factor 1 alpha (HIF1α). HIFs are transcription factors that promote hypoxia adaptation and have important functional roles in a wide range of ischemic and inflammatory diseases. To recreate the human PDR phenotype for a preclinical animal model, we generated a mouse with neuroretinal-specific loss of the von Hippel Lindau tumor suppressor protein, a protein that targets HIF1α for ubiquitination. We found that the neuroretinal cells in these mice overexpressed HIF1α and developed severe, irreversible ischemic retinopathy that has features of human PDR. Rapid progression of retinopathy in these mutant mice should facilitate the evaluation of therapeutic agents for ischemic and inflammatory blinding disorders. In addition, this model system can be used to manipulate the modulation of the hypoxia signaling pathways, for the treatment of non-ocular ischemic and inflammatory disorders
Circulating adrenomedullin estimates survival and reversibility of organ failure in sepsis: the prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock-1 (AdrenOSS-1) study
Background: Adrenomedullin (ADM) regulates vascular tone and endothelial permeability during sepsis. Levels of circulating biologically active ADM (bio-ADM) show an inverse relationship with blood pressure and a direct relationship with vasopressor requirement. In the present prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock 1 (, AdrenOSS-1) study, we assessed relationships between circulating bio-ADM during the initial intensive care unit (ICU) stay and short-term outcome in order to eventually design a biomarker-guided randomized controlled trial. Methods: AdrenOSS-1 was a prospective observational multinational study. The primary outcome was 28-day mortality. Secondary outcomes included organ failure as defined by Sequential Organ Failure Assessment (SOFA) score, organ support with focus on vasopressor/inotropic use, and need for renal replacement therapy. AdrenOSS-1 included 583 patients admitted to the ICU with sepsis or septic shock. Results: Circulating bio-ADM levels were measured upon admission and at day 2. Median bio-ADM concentration upon admission was 80.5 pg/ml [IQR 41.5-148.1 pg/ml]. Initial SOFA score was 7 [IQR 5-10], and 28-day mortality was 22%. We found marked associations between bio-ADM upon admission and 28-day mortality (unadjusted standardized HR 2.3 [CI 1.9-2.9]; adjusted HR 1.6 [CI 1.1-2.5]) and between bio-ADM levels and SOFA score (p < 0.0001). Need of vasopressor/inotrope, renal replacement therapy, and positive fluid balance were more prevalent in patients with a bio-ADM > 70 pg/ml upon admission than in those with bio-ADM ≤ 70 pg/ml. In patients with bio-ADM > 70 pg/ml upon admission, decrease in bio-ADM below 70 pg/ml at day 2 was associated with recovery of organ function at day 7 and better 28-day outcome (9.5% mortality). By contrast, persistently elevated bio-ADM at day 2 was associated with prolonged organ dysfunction and high 28-day mortality (38.1% mortality, HR 4.9, 95% CI 2.5-9.8). Conclusions: AdrenOSS-1 shows that early levels and rapid changes in bio-ADM estimate short-term outcome in sepsis and septic shock. These data are the backbone of the design of the biomarker-guided AdrenOSS-2 trial. Trial registration: ClinicalTrials.gov, NCT02393781. Registered on March 19, 2015
Experimental studies on vacancy induced ferromagnetism in undoped TiO2
Room temperature ferromagnetism is observed in undoped TiO2 films deposited
on Si substrates using pulsed laser deposition (PLD). The ferromagnetic
properties of the samples depend on the oxygen partial pressure during the PLD
synthesis. The appearance of higher binding energy component (HBEC) in the
oxygen 1s core peak from x-ray photoelectron spectroscopy (XPS) suggests the
presence of oxygen vacancies in these samples. The amount of oxygen during the
synthesis determines the vacancy concentration in the samples which is directly
related to the magnetic behavior of the samples. The magnetic moment decreases
with oxygen vacancy concentration in the samples. Valence band measurements
were performed to study the electronic structure of both stoichometric and
reduced TiO2. The analyses show the presence of Ti 3d band near the Fermi level
in reduced TiO2 samples. These bands are otherwise empty in stoichiometric TiO2
and reside in the conduction band which makes them unobservable by XPS. The
existence of this Ti 3d band near the Fermi level can possibly lead to Stoner
splitting of the band.Comment: 20 pages, 9 figur
Phase II randomised discontinuation trial of brivanib in patients with advanced solid tumours
Background: Brivanib is a selective inhibitor of vascular endothelial growth factor
and fibroblast growth factor (FGF) signalling. We performed a phase II randomised discontinuation trial of brivanib in 7 tumour types (soft-tissue sarcomas [STS], ovarian cancer, breast
cancer, pancreatic cancer, non-small-cell lung cancer [NSCLC], gastric/esophageal cancer and
transitional cell carcinoma [TCC]).
Patients and methods: During a 12-week open-label lead-in period, patients received brivanib
800 mg daily and were evaluated for FGF2 status by immunohistochemistry. Patients with stable disease at week 12 were randomised to brivanib or placebo. A study steering committee
evaluated week 12 response to determine if enrolment in a tumour type would continue.
The primary objective was progression-free survival (PFS) for brivanib versus placebo in patients with FGF2-positive tumours.
Results: A total of 595 patients were treated, and stable disease was observed at the week 12
randomisation point in all tumour types. Closure decisions were made for breast cancer,
pancreatic cancer, NSCLC, gastric cancer and TCC. Criteria for expansion were met for
STS and ovarian cancer. In 53 randomised patients with STS and FGF2-positive tumours,
the median PFS was 2.8 months for brivanib and 1.4 months for placebo (hazard ratio
[HR]: 0.58, p Z 0.08). For all randomised patients with sarcomas, the median PFS was 2.8
months (95% confidence interval [CI]: 1.4e4.0) for those treated with brivanib compared with
1.4 months (95% CI: 1.3e1.6) for placebo (HR Z 0.64, 95% CI: 0.38e1.07; p Z 0.09). In the
36 randomised patients with ovarian cancer and FGF2-positive tumours, the median PFS was
4.0 (95% CI: 2.6e4.2) months for brivanib and 2.0 months (95% CI: 1.2e2.7) for placebo (HR:
0.56, 95% CI: 0.26e1.22). For all randomised patients with ovarian cancer, the median PFS in
those randomised to brivanib was 4.0 months (95% CI: 2.6e4.2) and was 2.0 months (95% CI:
1.2e2.7) in those randomised to placebo (HR Z 0.54, 95% CI: 0.25e1.17; p Z 0.11).
Conclusion: Brivanib demonstrated activity in STS and ovarian cancer with an acceptable
safety profile. FGF2 expression, as defined in the protocol, is not a predictive biomarker of
the efficacy of brivanib
Religions in Vienna in the Past, Present and Future - Key Findings from the WIREL Project
The role of religion is currently a topic of considerable public interest in Vienna as well as across Europe. Over the course of the last half-century, Vienna has witnessed rapidly changing religious composition accompanied by consistently increasing religious diversity.
The various aspects of research conducted by WIREL facilitate the global assessment of both quantitative and qualitative aspects of religious diversity in Vienna. A short report – Religions in Vienna in the Past, Present and Future –summarises the research findings with the aim of making the trends, drivers, and socio-demographic consequences of the changing religious landscape of Vienna more accessible and understandable
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