42 research outputs found
Complex THz and DC inverse spin Hall effect in YIG/CuIr bilayers across a wide concentration range
We measure the inverse spin Hall effect of CuIr thin films on
yttrium iron garnet over a wide range of Ir concentrations (). Spin currents are triggered through the spin Seebeck effect,
either by a DC temperature gradient or by ultrafast optical heating of the
metal layer. The spin Hall current is detected by, respectively, electrical
contacts or measurement of the emitted THz radiation. With both approaches, we
reveal the same Ir concentration dependence that follows a novel complex,
non-monotonous behavior as compared to previous studies. For small Ir
concentrations a signal minimum is observed, while a pronounced maximum appears
near the equiatomic composition. We identify this behavior as originating from
the interplay of different spin Hall mechanisms as well as a
concentration-dependent variation of the integrated spin current density in
CuIr. The coinciding results obtained for DC and ultrafast
stimuli show that the studied material allows for efficient spin-to-charge
conversion even on ultrafast timescales, thus enabling a transfer of
established spintronic measurement schemes into the terahertz regime.Comment: 12 pages, 4 figure
Inverse modeling of thin layer flow cells for detection of solubility, transport and reaction coefficients from experimental data
Thin layer flow cells are used in electrochemical research as experimental devices which allow to perform investigations of electrocatalytic surface reactions under controlled conditions using reasonably small electrolyte volumes. The paper introduces a general approach to simulate the complete cell using accurate numerical simulation of the coupled flow, transport and reaction processes in a flow cell. The approach is based on a mass conservative coupling of a divergence-free finite element method for fluid flow and a stable finite volume method for mass transport. It allows to perform stable and efficient forward simulations that comply with the physical bounds namely mass conservation and maximum principles for the involved species. In this context, several recent approaches to obtain divergence-free velocities from finite element simulations are discussed. In order to perform parameter identification, the forward simulation method is coupled to standard optimization tools. After an assessment of the inverse modeling approach using known realistic data, first results of the identification of solubility and transport data for O2 dissolved in organic electrolytes are presented. A plausibility study for a more complex situation with surface reactions concludes the paper and shows possible extensions of the scope of the presented numerical tools
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Inverse modeling of thin layer flow cells for detection of solubility, transport and reaction coefficients from experimental data
Thin layer flow cells are used in electrochemical research as
experimental devices which allow to perform investigations of
electrocatalytic surface reactions under controlled conditions using
reasonably small electrolyte volumes. The paper introduces a general approach
to simulate the complete cell using accurate numerical simulation of the
coupled flow, transport and reaction processes in a flow cell. The approach
is based on a mass conservative coupling of a divergence-free finite element
method for fluid flow and a stable finite volume method for mass transport.
It allows to perform stable and efficient forward simulations that comply
with the physical bounds namely mass conservation and maximum principles for
the involved species. In this context, several recent approaches to obtain
divergence-free velocities from finite element simulations are discussed. In
order to perform parameter identification, the forward simulation method is
coupled to standard optimization tools. After an assessment of the inverse
modeling approach using known real-istic data, first results of the
identification of solubility and transport data for O2 dissolved in organic
electrolytes are presented. A plausibility study for a more complex situation
with surface reactions concludes the paper and shows possible extensions of
the scope of the presented numerical tools
Temperature dependent study of the spin dynamics of coupled YFeO/GdFeO/Pt trilayers
In this study, we investigate the dynamic response of a YFeO
(YIG)/ GdFeO (GdIG)/ Pt trilayer system by measurements of the
ferromagnetic resonance (FMR) and the pumped spin current detected by the
inverse spin Hall effect. This trilayer system offers the unique opportunity to
investigate the spin dynamics of the ferrimagnetic GdIG, close to its
compensation temperature. We show that our trilayer acts as a highly tunable
spin current source. Our experimental results are supported by micro-magnetic
simulations. As the detected spin current in the top Pt layer is distinctly
dominated by the GdIG layer, this gives the unique opportunity to investigate
the excitation and dynamic properties of GdIG while comparing it to the
broadband FMR absorption spectrum of the heterostructure
Silent diabetes mellitus, periodontitis, and a new case of thalamic abscess
Brain abscess is an unusual complication of uncontrolled diabetes. A solitary thalamic abscess is an uncommon type of brain abscess. We report a case of thalamic abscess, whereupon diabetes mellitus and periodontitis were diagnosed. The diagnosis and management of thalamic abscess, and the interplay of type 2 diabetes and periodontitis are discussed. A 56-year-old, Caucasian, man with no medical or travel history, presented with 5-day symptoms of meningeal irritation. Body mass index 30.6â
kg/m2. CT demonstrated a solitary midline lesion with neoplasia as a differential diagnosis. It was biopsied and cultures grew Streptococcus milleri. He was treated by stereotactic puncture, external drainage and targeted intrathecal and systemic antibiotic therapy. HIV negative but glycated haemoglobin (HbA1c) 10.7% (93â
mmol/mol). Dental examination revealed a small molar abscess. Radiological resolution of the thalamic abscess occurred within 2â
months. Diabetes improved with 7â
weeks of insulin, and maintained on metformin, HbA1c 6.9% (51â
mmol/mol). There was no residual neurological disability
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Ferroptosis in health and disease.
Ferroptosis is a pervasive non-apoptotic form of cell death highly relevant in various degenerative diseases and malignancies. The hallmark of ferroptosis is uncontrolled and overwhelming peroxidation of polyunsaturated fatty acids contained in membrane phospholipids, which eventually leads to rupture of the plasma membrane. Ferroptosis is unique in that it is essentially a spontaneous, uncatalyzed chemical process based on perturbed iron and redox homeostasis contributing to the cell death process, but that it is nonetheless modulated by many metabolic nodes that impinge on the cells susceptibility to ferroptosis. Among the various nodes affecting ferroptosis sensitivity, several have emerged as promising candidates for pharmacological intervention, rendering ferroptosis-related proteins attractive targets for the treatment of numerous currently incurable diseases. Herein, the current members of a Germany-wide research consortium focusing on ferroptosis research, as well as key external experts in ferroptosis who have made seminal contributions to this rapidly growing and exciting field of research, have gathered to provide a comprehensive, state-of-the-art review on ferroptosis. Specific topics include: basic mechanisms, in vivo relevance, specialized methodologies, chemical and pharmacological tools, and the potential contribution of ferroptosis to disease etiopathology and progression. We hope that this article will not only provide established scientists and newcomers to the field with an overview of the multiple facets of ferroptosis, but also encourage additional efforts to characterize further molecular pathways modulating ferroptosis, with the ultimate goal to develop novel pharmacotherapies to tackle the various diseases associated with - or caused by - ferroptosis
Identification of a novel polyfluorinated compound as a lead to inhibit human enzymes aldose reductase and AKR1B10 : structure determination of both ternary complexes and implications for drug design
Aldo-keto reductases (AKRs) are mostly monomeric enzymes which fold into a highly conserved ([alpha]/[beta])8 barrel, while their substrate specificity and inhibitor selectivity are determined by interaction with residues located in three highly variable external loops. The closely related human enzymes aldose reductase (AR or AKR1B1) and AKR1B10 are of biomedical interest because of their involvement in secondary diabetic complications (AR) and in cancer, e.g. hepatocellular carcinoma and smoking-related lung cancer (AKR1B10). After characterization of the IC50 values of both AKRs with a series of polyhalogenated compounds, 2,2',3,3',5,5',6,6'-octafluoro-4,4'-biphenyldiol (JF0064) was identified as a lead inhibitor of both enzymes with a new scaffold (a 1,1'-biphenyl-4,4'-diol). An ultrahigh-resolution X-ray structure of the AR-ÂNADP+-JF0064 complex has been determined at 0.85 Ă
resolution, allowing it to be observed that JF0064 interacts with the catalytic residue Tyr48 through a negatively charged hydroxyl group (i.e. the acidic phenol). The non-competitive inhibition pattern observed for JF0064 with both enzymes suggests that this acidic hydroxyl group is also present in the case of AKR1B10. Moreover, the combination of surface lysine methylation and the introduction of K125R and V301L mutations enabled the determination of the X-ray crystalloÂgraphic structure of the corresponding AKR1B10-NADP+-JF0064 complex. Comparison of the two structures has unveiled some important hints for subsequent structure-based drug-design efforts
Future mmVLBI Research with ALMA: A European vision
Very long baseline interferometry at millimetre/submillimetre wavelengths
(mmVLBI) offers the highest achievable spatial resolution at any wavelength in
astronomy. The anticipated inclusion of ALMA as a phased array into a global
VLBI network will bring unprecedented sensitivity and a transformational leap
in capabilities for mmVLBI. Building on years of pioneering efforts in the US
and Europe the ongoing ALMA Phasing Project (APP), a US-led international
collaboration with MPIfR-led European contributions, is expected to deliver a
beamformer and VLBI capability to ALMA by the end of 2014 (APP: Fish et al.
2013, arXiv:1309.3519).
This report focuses on the future use of mmVLBI by the international users
community from a European viewpoint. Firstly, it highlights the intense science
interest in Europe in future mmVLBI observations as compiled from the responses
to a general call to the European community for future research projects. A
wide range of research is presented that includes, amongst others:
- Imaging the event horizon of the black hole at the centre of the Galaxy
- Testing the theory of General Relativity an/or searching for alternative
theories
- Studying the origin of AGN jets and jet formation
- Cosmological evolution of galaxies and BHs, AGN feedback
- Masers in the Milky Way (in stars and star-forming regions)
- Extragalactic emission lines and astro-chemistry
- Redshifted absorption lines in distant galaxies and study of the ISM and
circumnuclear gas
- Pulsars, neutron stars, X-ray binaries
- Testing cosmology
- Testing fundamental physical constantsComment: Replaced figures 2 and 3: corrected position SRT. Corrected minor
typo in 5.
Lactate Improves Prediction of Short-Term Mortality in Critically Ill Patients With Cirrhosis: A Multinational Study
Lactate levels and lactate clearance are known predictors of outcome in critically ill patients in the intensive care unit (ICU). The prognostic value of lactate is not well established in liver cirrhosis and acute-on-chronic liver failure (ACLF). The aim of this study was to assess the prognostic value of lactate levels and clearance in critically ill patients with cirrhosis. Patients with cirrhosis admitted to the ICU were studied at the University Medical Center Hamburg-Eppendorf (n = 566, derivation cohort) and the Medical University of Vienna and the University Hospitals Leuven (n = 250, validation cohort). Arterial lactate was measured on admission and during the first 24 hours. Patients were followed for 1 year and outcome was assessed. Admission lactate was directly related to the number of organs failing and to 28-day mortality (area under receiver operating characteristic [AUROC] 0.72; P 0.70 for all). Lactate clearance had significant predictive ability for 28-day mortality in patients with elevated serum lactate â„5 mmol/L. Admission lactate and 12-hour lactate clearance (in patients with admission lactate â„5 mmol/L), respectively, were identified as significant predictors of 1-year mortality, independent of Chronic Liver Failure Consortium acute-on-chronic liver failure score (CLIF-C ACLFs). A lactate-adjusted CLIF-C ACLFs was developed (CLIF-C ACLFsLact ), which performed significantly better than the original CLIF-C ACLFs in prediction of 28-day mortality in the derivation and validation cohort. Conclusion: Lactate levels appropriately reflect severity of disease and organ failure and were independently associated with short-term mortality in critically ill patients with liver cirrhosis. Lactate is a simple but accurate prognostic marker, and its incorporation improved performance of CLIF-C ACLFs significantly.status: publishe
Elevated expression of complement C4 in the mouse prefrontal cortex causes schizophrenia-associated phenotypes
International audienceAccumulating evidence supports immune involvement in the pathogenesis of schizophrenia, a severe psychiatric disorder. In particular, high expression variants of C4, a gene of the innate immune complement system, were shown to confer susceptibility to schizophrenia. However, how elevated C4 expression may impact brain circuits remains largely unknown. We used in utero electroporation to overexpress C4 in the mouse prefrontal cortex. We found reduced glutamatergic input to pyramidal cells of juvenile and adult, but not of newborn C4-overexpressing (C4-OE) mice, together with decreased spine density, which mirrors spine loss observed in the schizophrenic cortex. Using time-lapse two-photon imaging in vivo, we observed that these deficits were associated with decreased dendritic spine gain and elimination in juvenile C4-OE mice, which may reflect poor formation and/or stabilization of immature spines. In juvenile and adult C4-OE mice, we found evidence for NMDA receptor hypofunction, another schizophrenia-associated phenotype, and synaptic accumulation of calcium-permeable AMPA receptors. Alterations in cortical GABAergic networks have been repeatedly associated with schizophrenia. We found that functional GABAergic transmission was reduced in C4-OE mice, in line with diminished GABA release probability from parvalbumin interneurons, lower GAD67 expression, and decreased intrinsic excitability in parvalbumin interneurons. These cellular abnormalities were associated with working memory impairment. Our results substantiate the causal relationship between an immunogenetic risk factor and several distinct cortical endophenotypes of schizophrenia and shed light on the underlying cellular mechanisms