Macromolecular Structure of a Commercial Humic Acid Sample

The molecular structure of a commercial sample of humic acids (HA) was investigated by membrane dialysis experiments (MD) and low-pressure size-exclusion chromatography (LP-SEC). MD showed that HA molecules were retained by dialysis membrane with a cut-off of 6–8 kDa, independently from HA concentration (15 or 150 mg L−1), NaHCO3 concentration (0.005–2.0 mol L−1), and from propan 2-ol (0–5 v/v %). SEC experiments at low pressure gave chromatograms with a broad peak, with an elution volume between those of the globular proteins bovine serum albumin (molecular weight = 66.5 kDa) and lysozyme from egg (molecular weight = 14.4 kDa). The pattern of the chromatogram did not vary with HA concentration, and second-run chromatograms of single eluted fractions showed relatively sharp peaks. From these data, we reveal that the commercial HA sample analysed has a macromolecular structure rather than being a supramolecular aggregate of relatively small molecules, as recently proposed for some samples of HA obtained from different sources

Non minimally coupled condensate cosmologies: matching observational data with phase space

We compare theoretical predictions with observations for a class of cosmological models in which the dark energy component is modeled as a fermionic condensate, non-minimally coupled with the gravitational eld and characterized by some specic selfinteraction potentials. Our analysis is based on the Markov Chain Monte Carlo Method (MCMC) and employs dierent data sets. It turns out that with an appropriate choice of parameters our models are fully compatible with several observed data. We combine these parameter values with phase space analysis to deduce the features of the entire cosmic history of the considered models

Evidence of a 2D Electron Gas in a Single-Unit-Cell of Anatase TiO2 (001)

The formation and the evolution of electronic metallic states localized at the surface, commonly termed 2D electron gas (2DEG), represents a peculiar phenomenon occurring at the surface and interface of many transition metal oxides (TMO). Among TMO, titanium dioxide (TiO2), particularly in its anatase polymorph, stands as a prototypical system for the development of novel applications related to renewable energy, devices and sensors, where understanding the carrier dynamics is of utmost importance. In this study, angle-resolved photo-electron spectroscopy (ARPES) and X-ray absorption spectroscopy (XAS) are used, supported by density functional theory (DFT), to follow the formation and the evolution of the 2DEG in TiO2 thin films. Unlike other TMO systems, it is revealed that, once the anatase fingerprint is present, the 2DEG in TiO2 is robust and stable down to a single-unit-cell, and that the electron filling of the 2DEG increases with thickness and eventually saturates. These results prove that no critical thickness triggers the occurrence of the 2DEG in anatase TiO2 and give insight in formation mechanism of electronic states at the surface of TMO

Local inhibition of ornithine decarboxylase reduces vascular stenosis in a murine model of carotid injury

Objectives: Polyamines are organic polycations playing an essential role in cell proliferation and differentiation, as well as in cell contractility, migration and apoptosis. These processes are known to contribute to restenosis, a pathophysiological process often occurring in patients submitted to revascularization procedures. We aimed to test the effect of alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase, on vascular cell pathophysiology in vitro and in a rat model of carotid arteriotomy-induced (re) stenosis. Methods: The effect of DFMO on primary rat smooth muscle cells (SMCs) and mouse microvascular bEnd. 3 endothelial cells (ECs) was evaluated through the analysis of DNA synthesis, polyamine concentration, cell viability, cell cycle phase distribution and by RT-PCR targeting cyclins and genes belonging to the polyamine pathway. The effect of DFMO was then evaluated in arteriotomy-injured rat carotids through the analysis of cell proliferation and apoptosis, RT-PCR and immunohistochemical analysis of differential gene expression. Results: DFMO showed a differential effect on SMCs and on ECs, with a marked, sustained anti-proliferative effect of DFMO at 3 and 8 days of treatment on SMCs and a less pronounced, late effect on bEnd. 3 ECs at 8 days of DFMO treatment. DFMO applied perivascularly in pluronic gel at arteriotomy site reduced subsequent cell proliferation and preserved smooth muscle differentiation without affecting the endothelial coverage. Lumen area in DFMO-treated carotids was 49% greater than in control arteries 4 weeks after injury. Conclusions: Our data support the key role of polyamines in restenosis and suggest a novel therapeutic approach for this pathophysiological process. (C) 2013 Elsevier Ireland Ltd. All rights reserved

Flat band separation and robust spin-Berry curvature in bilayer kagome metals

Kagome materials have emerged as a setting for emergent electronic phenomena that encompass different aspects of symmetry and topology. It is debated whether the XV$_6$Sn$_6$ kagome family (where X is a rare earth element), a recently discovered family of bilayer kagome metals, hosts a topologically non-trivial ground state resulting from the opening of spin-orbit coupling gaps. These states would carry a finite spin-Berry curvature, and topological surface states. Here, we investigate the spin and electronic structure of the XV$_6$Sn$_6$ kagome family. We obtain evidence for a finite spin-Berry curvature contribution at the center of the Brillouin zone, where the nearly flat band detaches from the dispersing Dirac band because of spin-orbit coupling. In addition, the spin-Berry curvature is further investigated in the charge density wave regime of ScV$_6$Sn$_6$, and it is found to be robust against the onset of the temperature-driven ordered phase. Utilizing the sensitivity of angle resolved photoemission spectroscopy to the spin and orbital angular momentum, our work unveils the spin-Berry curvature of topological kagome metals, and helps to define its spectroscopic fingerprint.Comment: 21 pages, 4 figure

Observation of termination-dependent topological connectivity in a magnetic Weyl Kagome lattice

The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation program under Marie Skłodowska-Curie Grant Agreement 897276. The authors gratefully acknowledge the Gauss Centre for Supercomputing e.V. (https://www.gauss-centre.eu) for funding this project by providing computing time on the GCS Supercomputer SuperMUC-NG at Leibniz Supercomputing Centre (https://www.lrz.de). The authors are grateful for funding support from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy through the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat (EXC 2147, Project 390858490), through FOR 5249-449872909 (Project P5), and through the Collaborative Research Center SFB 1170 ToCoTronics (Project 258499086). The authors greatly acknowledge the Diamond Light Source that supported the entire micro-ARPES experiment and corresponding costs. The Flatiron Institute is a division of the Simons Foundation. P.D.C.K. and C.B. gratefully acknowledge support from The Leverhulme Trust via Grant RL-2016-006.Engineering surfaces and interfaces of materials promises great potential in the field of heterostructures and quantum matter designers, with the opportunity to drive new many-body phases that are absent in the bulk compounds. Here, we focus on the magnetic Weyl kagome system Co3Sn2S2 and show how for the terminations of different samples the Weyl points connect differently, still preserving the bulk-boundary correspondence. Scanning tunneling microscopy has suggested such a scenario indirectly, and here, we probe the Fermiology of Co3Sn2S2 directly, by linking it to its real space surface distribution. By combining micro-ARPES and first-principles calculations, we measure the energy-momentum spectra and the Fermi surfaces of Co3Sn2S2 for different surface terminations and show the existence of topological features depending on the top-layer electronic environment. Our work helps to define a route for controlling bulk-derived topological properties by means of surface electrostatic potentials, offering a methodology for using Weyl kagome metals in responsive magnetic spintronics.Publisher PDFPeer reviewe

The role of immune suppression in COVID-19 hospitalization: clinical and epidemiological trends over three years of SARS-CoV-2 epidemic

Specific immune suppression types have been associated with a greater risk of severe COVID-19 disease and death. We analyzed data from patients >17 years that were hospitalized for COVID-19 at the “Fondazione IRCCS Ca′ Granda Ospedale Maggiore Policlinico” in Milan (Lombardy, Northern Italy). The study included 1727 SARS-CoV-2-positive patients (1,131 males, median age of 65 years) hospitalized between February 2020 and November 2022. Of these, 321 (18.6%, CI: 16.8–20.4%) had at least one condition defining immune suppression. Immune suppressed subjects were more likely to have other co-morbidities (80.4% vs. 69.8%, p < 0.001) and be vaccinated (37% vs. 12.7%, p < 0.001). We evaluated the contribution of immune suppression to hospitalization during the various stages of the epidemic and investigated whether immune suppression contributed to severe outcomes and death, also considering the vaccination status of the patients. The proportion of immune suppressed patients among all hospitalizations (initially stable at <20%) started to increase around December 2021, and remained high (30–50%). This change coincided with an increase in the proportions of older patients and patients with co-morbidities and with a decrease in the proportion of patients with severe outcomes. Vaccinated patients showed a lower proportion of severe outcomes; among non-vaccinated patients, severe outcomes were more common in immune suppressed individuals. Immune suppression was a significant predictor of severe outcomes, after adjusting for age, sex, co-morbidities, period of hospitalization, and vaccination status (OR: 1.64; 95% CI: 1.23–2.19), while vaccination was a protective factor (OR: 0.31; 95% IC: 0.20–0.47). However, after November 2021, differences in disease outcomes between vaccinated and non-vaccinated groups (for both immune suppressed and immune competent subjects) disappeared. Since December 2021, the spread of the less virulent Omicron variant and an overall higher level of induced and/or natural immunity likely contributed to the observed shift in hospitalized patient characteristics. Nonetheless, vaccination against SARS-CoV-2, likely in combination with naturally acquired immunity, effectively reduced severe outcomes in both immune competent (73.9% vs. 48.2%, p < 0.001) and immune suppressed (66.4% vs. 35.2%, p < 0.001) patients, confirming previous observations about the value of the vaccine in preventing serious disease

Practical guidelines for rigor and reproducibility in preclinical and clinical studies on cardioprotection

The potential for ischemic preconditioning to reduce infarct size was first recognized more than 30 years ago. Despite extension of the concept to ischemic postconditioning and remote ischemic conditioning and literally thousands of experimental studies in various species and models which identified a multitude of signaling steps, so far there is only a single and very recent study, which has unequivocally translated cardioprotection to improved clinical outcome as the primary endpoint in patients. Many potential reasons for this disappointing lack of clinical translation of cardioprotection have been proposed, including lack of rigor and reproducibility in preclinical studies, and poor design and conduct of clinical trials. There is, however, universal agreement that robust preclinical data are a mandatory prerequisite to initiate a meaningful clinical trial. In this context, it is disconcerting that the CAESAR consortium (Consortium for preclinicAl assESsment of cARdioprotective therapies) in a highly standardized multi-center approach of preclinical studies identified only ischemic preconditioning, but not nitrite or sildenafil, when given as adjunct to reperfusion, to reduce infarct size. However, ischemic preconditioning—due to its very nature—can only be used in elective interventions, and not in acute myocardial infarction. Therefore, better strategies to identify robust and reproducible strategies of cardioprotection, which can subsequently be tested in clinical trials must be developed. We refer to the recent guidelines for experimental models of myocardial ischemia and infarction, and aim to provide now practical guidelines to ensure rigor and reproducibility in preclinical and clinical studies on cardioprotection. In line with the above guideline, we define rigor as standardized state-of-the-art design, conduct and reporting of a study, which is then a prerequisite for reproducibility, i.e. replication of results by another laboratory when performing exactly the same experiment