Oxygen diffusion and vacancy migration thermally-activated govern high-temperature magnetism in ceria.

Several experimental works currently demonstrate that metallic nano-oxides and carbon nanomaterials expected to be diamagnets, in fact, behave as ferromagnets at room temperature. More than scientifically intriguing, this unconventional and unexpected ferromagnetism pave the way for innovation products and novel nanotechnological applications, gathering the magnetism to interesting functionalities of these nanomaterials. Here, we investigate the non-conventional ferromagnetism observed at high temperatures in nanocrystalline cerium dioxide (CeO2or nanoceria) thin films that are optically transparent to visible light. Nanoceria exhibits several concrete applications in catalytic processes, photovoltaic cells, solid-state fuel cells, among others, which are mostly due to natural presence of oxygen vacancies and easy migration of the oxygen through the structure. The ferromagnetism in non-stoichiometric nanocrystaline ceria can be consistently described by ab initio electronic structure calculations, which support that oxygen vacancies cause the formation of magnetic moments and can provide a robust interconnectivity within magnetic polarons theoretical framework. Additionally, we present a conceptual model to account the oxygen transport to the non-conventional ferromagnetism at temperatures well above room temperature. The approach is complementary to the thermally-activated effective transfers of charge and spin around oxygen vacancy centers.

Histopathological Findings Associated With Gastroesophageal Reflux Disease and Aspiration After Lung Transplantation: Initial Brazilian Single-Center Experience.

BACKGROUND: Gastro-esophageal reflux disease (GERD) and broncho-aspiration (BA) are known to increase the risk for chronic lung allograft dysfunction (CLAD). However, specific lung injury mechanisms are not clearly known. The objective of the study was to describe histopathological findings in surveillance lung transbronchial biopsies that can be correlated with episodes of BA in the lung allograft. METHODS: This retrospective analysis of surveillance transbronchial biopsies was performed in lung transplant recipients, with available data of broncho-alveolar fluid (cultures and cytology), lung function parameters, and esophageal functional tests. RESULTS: Were analyzed 11 patients, divided into 3 groups: (1) GERD group: 4 patients with GERD and CLAD diagnosis; (2) control group: 2 patients without GERD or CLAD; and (3) BA group: 5 patients with foreign material in lung biopsies. A histopathological pattern of neutrophilic bronchitis (NB) was present in 4 of 4 cases in the GERD group and in 1 of 5 cases in the BA group in 2 or more biopsy samples; culture samples were all negative; the 5 NB-positive patients developed CLAD and died (3/5) or needed re-transplantation (2/5). The other 3 patients in the BA group had GERD without NB or CLAD. Both patients in the control group had transient NB in biopsies with positive cultures but remained free of CLAD. CONCLUSIONS: Surveillance transbronchial biopsies may provide useful information other than the evaluation of acute cellular rejection and can help to identify high-risk patients for allograft dysfunction related to gastro-esophageal reflux.

Stents for bronchial stenosis after lung transplantation: should they be removed?

BACKGROUND: Airway complications after lung transplantation are the major cause of morbidity, affecting up to 33% of all cases. Bronchial stenosis is the most common complication. The use of stents has been established as the most effective therapy; however, their removal is recommended after 3-6 months of use. We have been using self-expandable stents as a definitive treatment and remove them only if necessary. For this report, we evaluated the use of self-expandable stents as a definitive treatment for bronchial stenosis after lung transplantation. METHODS: We performed a retrospective cohort study to evaluate patients with bronchial stenosis from August 2003 to April 2014. Clinical and pulmonary function test data were collected. RESULTS: Two hundred lung transplants were performed, 156 of which were bilateral. Sixteen patients experienced airway complications: 4 had dehiscence, 2 necrosis, and 10 bronchial stenosis. Of these patients, 7 had undergone bilateral procedures, and 2 patients developed stenosis in both sides. Twelve anastomotic stenoses were observed. The follow-up after stenting ranged from 1 to 7 years. All patients had increased lung function, and 4 remained stable with sustained increase in pulmonary function without episodes of infection. Three patients required removal of their prosthesis 6 months to 1 year after implantation because of complications. Two patients died owing to unrelated causes. CONCLUSIONS: Definitive treatment of bronchial stenosis with self-expandable stents is a viable option. The 1st year seems to be the most crucial for determining definitive treatment, because no patients required removal of their stent after 1 year.

Posterior reversible encephalopathy syndrome in lung transplantation: 5 case reports.

Posterior reversible encephalopathy syndrome (PRES) is a cliniconeuroradiologic entity characterized by typical neurologic symptoms with characteristic cerebral image alterations. It has been reported in solid organ transplantations, especially related to the use of calcineurin inhibitors. The incidence of PRES in lung transplantation is unknown and probably under-reported in the literature. Here we describe 5 cases of PRES after bilateral lung transplantation. One of the reported cases was the first in the literature in which the neurologic onset precluded the introduction of calcineurin inhibitor. Therefore, although calcineurin inhibitors are known to play an important role in the development of PRES in the setting of lung transplantation, other causes seems to be involved in the physiopathology of this syndrome.

Fungal infection by Mucorales order in lung transplantation: 4 case reports.

Mucorales is a fungus that causes systemic, highly lethal infections in immunocompromised patients. The overall mortality of pulmonary mucormycosis can reach 95%. This work is a review of medical records of 200 lung transplant recipients between the years of 2003 and 2013, in order to identify the prevalence of Mucorales in the Lung Transplantation service of Heart Institute (InCor), Hospital das Clínicas da Universidade de São Paulo, Brazil, by culture results from bronchoalveolar lavage and necropsy findings. We report 4 cases found at this analyses: 3 in patients with cystic fibrosis and 1 in a patient with bronchiectasis due to Kartagener syndrome. There were 2 unfavorable outcomes related to the presence of Mucorales, 1 by reduction of immunosuppression, another by invasive infection. Another patient died from renal and septic complications from another etiology. One patient was diagnosed at autopsy just 5 days after lung transplantation, with the Mucor inside the pulmonary vein with a precise, well-defined involvement only of donor's segment, leading to previous colonization hypothesis. There are few case reports of Mucorales infection in lung transplantation in the literature. Surveillance for the presence of Mucor can lead to timely fungal treatment and reduce morbidity and mortality in the immunocompromised patients, especially lung transplant recipients.

Tuning protein GlnB-Hs surface interaction with silicon: FTIR-ATR, AFM and XPS study.

Herbaspirillum seropedicae GlnB (GlnB-Hs) is a signal transduction protein involved in the control of nitrogen, carbon and energetic metabolism. The adsorption of GlnB-Hs deposited by spin coating on hydrophilic and hydrophobic silicon forms a thin layer that was characterized using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR). AFM allowed the identification of globular, face-up donut like array of protein on hydrophilic silicon substrate, favoring deprotonated residues to contact the silicon oxide surface. Over hydrophobic silicon, GlnB-Hs adopts a side-on conformation forming a filament network, avoiding the contact of protonated residues with silicon surface. XPS allowed us to determine the protonated and non-protonated states of nitrogen 1s (N 1s). The FTIR-ATR measurements provided information about protein secondary structure and its conservation, after surface adsorption.

Adsorption of protein GlnB of Herbaspirillum seropedicae on Si(111) investigated by AFM and XPS.

The protein GlnB-Hs (GlnB of Herbaspirillum seropedicae) in diazotroph micro-organisms signalizes levels of nitrogen, carbon, and energy for a series of proteins involved in the regulation of expression and control of the activity of nitrogenase complex that converts atmospheric nitrogen in ammonia, resulting in biological nitrogen fixation. Its structure has already been determined by X-ray diffraction, revealing a trimer of (36 kDa) with lateral cavities having hydrophilic boundaries. The interactions of GlnB-Hs with the well-known Si(111) surface were investigated for different incubation times, protein concentrations in initial solution, deposition conditions, and substrate initial state. The protein solution was deposited on Si(111) and dried under controlled conditions. An atomic force microscope operating in dynamic mode shows images of circular, linear, and more complex donut-shaped protein arrangement, and also filament types of organization, which vary from a few nanometers to micrometers. Apparently, the filament formation was favored because of protein surface polarity when in contact with the silicon surface, following some specific orientation. The spin-coating technique was successfully used to obtain more uniform surface covering.

Structure of ferromagnetic CrAs epilayers grown on GaAs(001).

Magnetic and structural properties of CrAs epilayers grown on GaAs(001) by molecular beam epitaxy have been studied. CrAs epilayers are orthorhombic for all thicknesses investigated but show a structural transition from a metastable phase for very thin films, to the usual bulk MnP-type orthorhombic phase at higher thicknesses. At intermediate thicknesses, there is a predominance of the new phase, although a contribution from the usual CrAs bulk phase remains clearly present. These results strongly suggest that the ferromagnetic signal measured at room temperature comes from the new metastable orthorhombic structure with an expanded b-axis induced by the substrate strain.