Thermoelectric behavior of Ruddlesden-Popper series iridates

The goal of this work is studying the evolution of thermoelectric transport across the members of the Ruddlesden-Popper series iridates Srn+1IrnO3n+1, where a metal-insulator transition driven by bandwidth change occurs, from the strongly insulating Sr2IrO4 to the metallic non Fermi liquid behavior of SrIrO3. Sr2IrO4 (n=1), Sr3Ir2O7 (n=2) and SrIrO3 (n=inf.) polycrystals are synthesized at high pressure and characterized by structural, magnetic, electric and thermoelectric transport analyses. We find a complex thermoelectric phenomenology in the three compounds. Thermal diffusion of charge carriers accounts for the Seebeck behavior of Sr2IrO4, whereas additional drag mechanisms come into play in determining the Seebeck temperature dependence of Sr3Ir2O7 and SrIrO3. These findings reveal close relationship between magnetic, electronic and thermoelectric properties, strong coupling of charge carriers with phonons and spin fluctuations as well as relevance of multiband description in these compounds.Comment: main paper + supplementary informatio

Ferroelectric order driven Eu3+ photoluminescence in BaZrxTi1−xO3 perovskite

The ability to tune and enhance the properties of luminescent materials is essential for enlarging their application potential. Recently, the modulation of the photoluminescence emission of lanthanide-doped ferroelectric perovskites by applying an electric field has been reported. Herein, we show that the ferroelectric order and, more generally the polar order, has a direct effect on the photoluminescence of Eu3+ in the model BaZrxTi1-xO3 perovskite even in the absence of an external field. The dipole arrangement evolves with increasing xfrom long-range ferroelectric order to short-range order typical of relaxors until the non-polar paraelectric BaZrO3 is achieved. The cooperative polar interactions existing in the lattice (x < 1) promote the off-center displacement of the Eu3+ ion determining a change of the lanthanide site symmetry and, consequently, an abrupt variation of the photoluminescence emission with temperature. Each type of polar order is characterized by a distinct photoluminescence behaviour

The local and average structure of Ba(Ti, Ce)O3 perovskite solid solution: effect of cerium concentration and particle size

The amazing properties of ferroelectric perovskite BaTiO3 (BT) and its solid solutions make them indispensable for many technological applications (e.g. multilayer capacitors). Unfortunately, the so-called `size effect' limits their use. Indeed, under a certain critical particle size, these materials show a suppression of the spontaneous polarization and thus of the ferroelectric properties. In pure nanometric BaTiO3, this is related to a certain local structural disorder. However, only a few studies have explored BT solid solutions, where the doping effect, coupled to the reduced particle size, can play an important role. Therefore, in this work, the structure of BaCexTi1\u2013xO3 (x = 0.02\u20130.20) was explored by traditional Rietveld method and Pair Distribution Function. Samples present a particle size from 80\u2013160 nm to 400\u20131000 nm depending on increasing x. The carbox approach was applied, investigating the evolution of the local structure, its modifications and the structural coherent correlation length, as a function of cerium amount. Results demonstrate a cooperative effect of composition and reduced size in the ferroelectricity loss. The two, in fact, contribute to intensify the local structural disorder, decreasing the structural coherent correlation length. The local structural disorder is thus confirmed to be a relevant factor in the ferroelectric properties degradation

Sudden death after valve-in-valve procedure due to delayed coronary obstruction. A case report

Background: Valve-in-valve transcatheter aortic valve implantation for degenerated aortic bioprostheses is an effective option for patients at high risk for redo surgery, even if it may be burdened by complications more common in specific settings, such as, coronary artery obstruction. Case presentation: We present the case of a Caucasic 84-year-old woman with degeneration of a previously implanted aortic Mitroflow bioprosthesis. She underwent a valve-in-valve transcatheter aortic valve implantation with a CoreValve® bioprosthesis. End-procedure coronary angiography demonstrated maintained perfusion of both coronary arteries. However, few hours later, she experienced sudden cardiac death. An autopsy showed that Mitroflow prosthesis leaflets were higher than the left main coronary ostium, and no other possible cause for the sudden death. Fatality was thus ascribed to left main coronary ostium obstruction due to apposition of the Mitroflow leaflet pushed upward by the late expansion of CoreValve®. Conclusions: Coronary artery obstruction is a frequently fatal complication which usually presents just after valve implantation, but, as reported in our case, it may also have a delayed presentation. Accurate patient's selection and intraoperative preventive measures can reduce this eventuality

Urgent cesarean delivery following a spontaneous coronary artery dissection

Objective: Rare disease Background: Spontaneous coronary artery dissection is the most common etiology of pregnancy-associated myocardial infarction. It is characterized by high rates of maternal morbidity and mortality and may cause fetal complications and death as well. Case Report: A 44-year-old female (G2P1) suffered from pregnancy-related spontaneous coronary artery dissection with dissection of distal left anterior descending coronary artery. The patient was hemodynamically stable and did not required revascularization, but signs of fetal distress were detected and thus an urgent cesarean delivery was performed. This emergency procedure was undertaken in the catheterization laboratory (Cath-Lab) right after coronary angiography, thanks to a multidisciplinary team. Health conditions of the newborn were good. The patient instead suffered from a recurrence of spontaneous coronary artery dissection 6 days later, complicated by left ventricular apical thrombus and epistenocardial pericarditis. The dissection self-healed in 1 month. Conclusions: Careful evaluation of pregnancy-related spontaneous coronary artery dissection is needed to assess and manage both maternal and fetal complications. Under specific circumstances, a cesarean delivery may be required and be even performed in the Cath-Lab after coronary catheterization

Encuesta de anticuerpos de enfermedad de Marek en aves de vida libre de la provincia de Buenos Aires

La enfermedad de Marek (EM) es un linfoma de células T inducido en pollos por el virus de la EM (VEM) que es altamente asociado a células. Las lesiones de EM consisten en linfomas de células T CD4 + que afectan a un número de órganos y tejidos, incluyendo iris, la piel y vísceras, junto con infiltración de células linfoides en los nervios periféricos que resultan en síntomas de parálisis. La enfermedad, causada por un herpesvirus, y se puede distinguir etiológicamente de otras neoplasias linfoides de aves. EM es y ha sido controlado desde principios de los años 1970 mediante el uso de las vacunas. Durante las últimas cuatro décadas, la investigación sobre EM ha proporcionado una mayor comprensión de los mecanismos moleculares de la enfermedad y los factores que afectan a la resistencia genética. Sin embargo, a pesar del uso generalizado de vacunas y el desarrollo de nuevos métodos de vacunación, la EM sigue siendo un reto importante para la salud de las aves comerciales, en particular por el continuo aumento de la virulencia de las cepas del VEM. Es evidente que, en ausencia de medidas de control, incluyendo “fallas de vacunas”, la EM es capaz de causar pérdidas devastadoras. Como una enfermedad que ocurre en todo el mundo, con los informes de las fallas de vacunación y la aparición probable de patotipos más virulentos, la EM plantea graves amenazas para la industria avícola, y desarrollar estrategias para su control sigue siendo uno de los grandes retos. Además, la incidencia de EM en otras especies de aves tales como pavos y gansos demuestra la gama de huéspedes y el aumento de importancia económica. Sin embargo, el papel de EM en aves de vida libre nunca ha sido estudiado profundamente. Se evaluará Una encuesta preliminar de anticuerpos en las aves de vida libre.Facultad de Ciencias Veterinaria

Anterior mitral valve aneurysm is an uncommon complication of aortic valve infective endocarditis. A case report

Objective: Rare disease Background: Mitral valve aneurysms (MVAs) are uncommon conditions frequently associated with aortic valve endocarditis. They may be complicated by perforation and severe mitral regurgitation (MR). Optimal treatment of MVA, and in particular the best timing for surgery, are uncertain. Case Report: A 62-year-old man with a recent history of dental surgery presented to the Emergency Department complaining relapsing fever. A first echocardiogram demonstrated infective endocarditis of the aortic valve. The patient was primarily managed with specific antibiotic therapy. Despite this, a few days later he suffered from splen-ic embolization and an MVA with MR was detected. Surgical replacement of the mitral and aortic valves was therefore performed. Conclusions: MVAs are infrequent but potentially severe complications of AV endocarditis. In the absence of definite treatment indication, the correct time for surgery should depend on concomitant clinical and infective features

Delayed left subclavian artery pseudoaneurysm following transcatheter aortic valve implantation

In 10-15% of patients undergoing transcatheter aortic valve implantation (TAVI), the femoral artery approach is precluded owing to insufficient caliber or tortuosity of the vessel. In these subjects, the subclavian (SC) or the axillary (AX) access can be used; these have proved equivalent to the femoral artery approach in terms of both survival and the rate of vascular complications. The SC or AX approach usually require a surgical cut-down under general anesthesia or deep sedation, though cases have been described in which the percutaneous technique has been adopted. Furthermore, SC and AX access may be burdened by complications, such as vessel perforation or rupture, or the formation of aneurysms at the site of incision

A bit stickier, a bit slower, a lot stiffer: Specific vs. nonspecific binding of gal4 to dna

Transcription factors regulate gene activity by binding specific regions of genomic DNA thanks to a subtle interplay of specific and nonspecific interactions that is challenging to quantify. Here, we exploit Reflective Phantom Interface (RPI), a label-free biosensor based on optical reflectivity, to investigate the binding of the N-terminal domain of Gal4, a well-known gene regulator, to double-stranded DNA fragments containing or not its consensus sequence. The analysis of RPI-binding curves provides interaction strength and kinetics and their dependence on temperature and ionic strength. We found that the binding of Gal4 to its cognate site is stronger, as expected, but also markedly slower. We performed a combined analysis of specific and nonspecific binding— equilibrium and kinetics—by means of a simple model based on nested potential wells and found that the free energy gap between specific and nonspecific binding is of the order of one kcal/mol only. We investigated the origin of such a small value by performing all-atom molecular dynamics simulations of Gal4–DNA interactions. We found a strong enthalpy–entropy compensation, by which the binding of Gal4 to its cognate sequence entails a DNA bending and a striking conformational freezing, which could be instrumental in the biological function of Gal4

New &quot;clickable&quot; polymeric coating for glycan microarrays

The interaction of carbohydrates with a variety of biological targets, including antibodies, proteins, viruses and cells are of utmost importance in many aspects of biology. Glycan microarrays are increasingly used to determine the binding specificity of glycan-binding proteins. In this study, a novel slide is reported for the fabrication of glycan arrays that combines the higher sensitivity of a layered Si-SiO2 with a novel approach to form a polymeric coating easily modifiable by subsequent click reaction. The alkyne-containing copolymer, adsorbed from an aqueous solution, produces a coating by a single step procedure and serves as a soft, tridimensional support for the oriented immobilization of carbohydrates via azide/alkyne Cu(I) catalyzed "click" reaction. The equilibrium and kinetics parameters of the interaction of Concanavalin A with eight synthetic glycans were determined using fluorescence microarray and Reflective Phantom Interface (RPI), a recently proposed optical label-free detection approach. The enhancement of fluorescence provided by the Si-SiO2 slides enabled to extend the limit of detection at lower surface densities of lectins, in turn enabling the study of the interaction for a wide range of glycans surface density. Equilibrium dissociation constants of a few nM were extracted for multivalent glycan-lectin binding, mimicking the conditions of biological membranes, whereas hundreds of nM were observed at the lower glycan surface densities