Magnetic Anisotropy of Maghemite Nanoparticles Probed by RF Transverse Susceptibility

AbstractWe present radio frequency magnetic transverse susceptibility measurements on γ-Fe2O3 nanoparticles, which yield an estimation of their effective anisotropy constant, Keff as a function of nanoparticle size. The resulting values range from 4 to 8 × 104 erg/cm3, being on the order of the magnetocrystalline anisotropy in bulk maghemite. Keff values increase as the particle diameter increases. Evidences of anisotropy field distribution given by the size distribution in the samples, and interparticle interactions that increase as the particle size increases, are also observed in the TS measurements. The effects of such interparticle interaction overcome those of thermal fluctuations, in contrast with the behavior of other iron oxide particles

Quadrupolar XMCD at the Fe K -edge in Fe phthalocyanine film on Au: Insight into the magnetic ground state

The observation of an anomalous quadrupolar signal in x-ray magnetic circular dichroism (XMCD) at the Fe K-edge of iron phthalocyanine (FePc) films is reported. All ground states previously suggested for FePc are incompatible with the experimental data. Based on ab initio molecular orbital multiplet calculations of the isolated FePc molecule, we propose a model for the magnetic ground state of the FePc film that explains the XMCD data and reproduces the observed values of the orbital moments in the perpendicular and planar directions

Las anomalías precoces de la continuidad en el discurso constituyen biomarcadores predictivos de psicosis

Language is being systematized as an area of clinical research because it contains features that function as a biomarker for the prediction of psychosis. The aim of the study was to contrast two types of continuity features such as connection, iteration, and referential distance, and, on the other hand, those of verbal fluency, understood as the presence of aberrant pauses. Clinical interviews of 10 patients diagnosed with schizophrenia, 10 CHR and 10 healthy controls were analyzed. For the analysis of referentiality, sentence windows were selected and for verbal fluency, 15 minutes of speech were considered. The results suggest the presence of abnormalities in referentiality and verbal fluency among the CHR population. These similarities are found in terms of occurrence and similarity to those of the schizophrenia group, which supports our hypothesis that they are predictive biomarkers.El lenguaje se está sistematizando como área de pesquisa clínica porque contiene características que funcionan como un biomarcador para la predicción de psicosis. El objetivo del estudio fue contrastar dos tipos de características de continuidad discursiva entre personas que cursan Estados Mentales de Alto Riesgo (CHR) y personas con diagnóstico de esquizofrenia. Nos referimos, por una parte, a características referenciales, tales como conexión, iteración y distancia referencial, y, por otra, a las de fluidez verbal, entendida como la presencia de pausas aberrantes. Se analizaron entrevistas clínicas de 10 pacientes diagnosticados de esquizofrenia, 10 CHR y 10 controles sanos. Para el análisis de la referencialidad se seleccionaron ventanas de oraciones y para la fluidez verbal se consideraron 15 minutos de habla. Los resultados apuntan a que existe presencia de anomalías en referencialidad y en fluidez verbal entre la población CHR. Dichas similitudes se dan en cuanto a ocurrencia y similitud respecto a las del grupo con esquizofrenia, lo que refrenda nuestra hipótesis de que constituyen biomarcadores predictivos.  

Perpendicular magnetic anisotropy in granular multilayers of COPD alloyed nanoparticles

Co-Pd multilayers obtained by Pd capping of pre-deposited Co nanoparticles on amorphous alumina are systematically studied by means of high-resolution transmission electron microscopy, x-ray diffraction, extended x-ray absorption fine structure, SQUID-based magnetometry, and x-ray magnetic circular dichroism. The films are formed by COPD alloyed nanoparticles self-organized across the layers, with the interspace between the nanoparticles filled by the non-alloyed Pd metal. The nanoparticles show atomic arrangements compatible with short-range chemical order of L10 strucure type. The collective magnetic behavior is that of ferromagnetically coupled particles with perpendicular magnetic anisotropy, irrespective of the amount of deposited Pd. For increasing temperature three magnetic phases are identified: hard ferromagnetic with strong coercive field, soft-ferromagnetic as in an amorphous asperomagnet, and superparamagnetic. Increasing the amount of Pd in the system leads to both magnetic hardness increment and higher transition temperatures. Magnetic total moments of 1.77(4) µB and 0.45(4) µB are found at Co and Pd sites, respectively, where the orbital moment of Co, 0.40(2) µB, is high, while that of Pd is negligible. The effective magnetic anisotropy is the largest in the capping metal series (Pd, Pt, W, Cu, Ag, Au), which is attributed to the interparticle interaction between de nanoparticles, in addition to the intraparticle anisotropy arising from hybridization between the 3d-4d bands associated to the Co and Pd chemical arrangement in a L10 structure type

Perpendicular magnetic anisotropy in Co–Pt granular multilayers

Magnetization hysteresis curves have been measured on Co granular multilayers, (Al₂O₃/Co/Pt)N (N = 1 and 25), with the applied magnetic field parallel and perpendicular to the substrate plane. In all samples perpendicular magnetic anisotropy was observed. For Co particles with average diameter 3 nm, the coercive field at low temperature is μ₀HC = 0.5 T. HC decreases for increasing temperature and disappears at ≈200 K. A soft magnetic component is also present in all samples up to the freezing temperature Tf = 365 K. Co and Pt XMCD measurements at the L2,3 edges were performed, yielding to the orbital mL and spin mS contributions to the total magnetic moment of the system. These results, in addition to XANES ones, indicate the presence of CoxPt₁₋x alloy. Particles conformed of CoPt alloy, embedded in Pt and coupled magnetically by dipolar or RKKY interaction, may explain the phenomenology observed in these systems

Phase I clinical trial in healthy adults of a nasal vaccine candidate containing recombinant hepatitis B surface and core antigens

SummaryBackgroundThe nasal vaccine candidate (NASVAC), comprising hepatitis B virus (HBV) surface (HBsAg) and core antigens (HBcAg), has been shown to be highly immunogenic in animal models.MethodsA phase I double-blinded, placebo-controlled randomized clinical trial was carried out in 19 healthy male adults with no serologic markers of immunity/infection to HBV. This study was aimed at exploring the safety and immunogenic profile of nasal co-administration of both HBV recombinant antigens. The trial was performed according to Good Clinical Practice guidelines. Participants ranged in age from 18 to 45 years and were randomly allocated to receive a mixture of 50μg HBsAg and 50μg HBcAg or 0.9% physiologic saline solution, as a placebo, via nasal spray in a five-dose schedule at 0, 7, 15, 30, and 60 days. A total volume of 0.5ml was administered in two dosages of 125μl per nostril. Adverse events were actively recorded 1h, 6h, 12h, 24h, 48h, 72h, 7 days and 30 days after each dose. Anti-HBs and anti-HBc titers were evaluated using corresponding ELISA kits at days 30 and 90.ResultsThe vaccine candidate was safe and well tolerated. Adverse reactions included sneezing (34.1%), rhinorrhea (12.2%), nasal stuffiness (9.8%), palate itching (9.8%), headache (9.8%), and general malaise (7.3%). These reactions were all self-limiting and mild in intensity. No severe or unexpected events were recorded during the trial. The vaccine elicited anti-HBc seroconversion in 100% of subjects as early as day 30 of the immunization schedule, while a seroprotective anti-HBs titer (≥10IU/l) was at a maximum at day 90 (75%). All subjects in the placebo group remained seronegative during the trial.ConclusionThe HBsAg–HBcAg vaccine candidate was safe, well tolerated and immunogenic in this phase I study in healthy adults. To our knowledge, this is the first demonstration of safety and immunogenicity for a nasal vaccine candidate comprising HBV antigens

Consenso mexicano sobre detección y tratamiento del cáncer gástrico incipiente

El cáncer gástrico representa una de las neoplasias más frecuentes en el aparato digestivo y en la mayoría de los casos es el resultado de la progresión de lesiones premalignas. La detección oportuna de estas lesiones es relevante ya que un tratamiento oportuno brinda la posibilidad de curación. En nuestro país no existía un consenso respecto a la detección temprana del cáncer gástrico, por lo que la Asociación Mexicana de Gastroenterología reunió aun grupo de expertos y realizó el Consenso sobre detección y tratamiento del cáncer gástricoincipiente (CGI) para establecer recomendaciones de utilidad para la comunidad médica. Eneste consenso se utilizó la metodología Delphi y se emitieron 38 recomendaciones al respectodel CGI. El consenso define el CGI como aquel que al momento del diagnóstico se encuentralimitado a la mucosa y a la submucosa, independientemente de metástasis en ganglios linfáticos.En México, como otras partes del mundo, los factores asociados al CGI incluyen la infección porHelicobacter pylori, los antecedentes familiares, el tabaquismo y los factores dietéticos. Para eldiagnóstico se recomienda utilizar cromoendoscopia, magnificación y equipos con luz mejorada.Un diagnóstico histopatológico preciso es invaluable para tomar de decisiones terapéuticas. Eltratamiento endoscópico del CGI, ya sea disección o resección de la mucosa, debe ser preferidoal manejo quirúrgico cuando se puedan obtener resultados semejantes en términos de curaciónoncológica. La vigilancia endoscópica se deberá de individualizar

EPIdemiology of Surgery-Associated Acute Kidney Injury (EPIS-AKI) : Study protocol for a multicentre, observational trial

More than 300 million surgical procedures are performed each year. Acute kidney injury (AKI) is a common complication after major surgery and is associated with adverse short-term and long-term outcomes. However, there is a large variation in the incidence of reported AKI rates. The establishment of an accurate epidemiology of surgery-associated AKI is important for healthcare policy, quality initiatives, clinical trials, as well as for improving guidelines. The objective of the Epidemiology of Surgery-associated Acute Kidney Injury (EPIS-AKI) trial is to prospectively evaluate the epidemiology of AKI after major surgery using the latest Kidney Disease: Improving Global Outcomes (KDIGO) consensus definition of AKI. EPIS-AKI is an international prospective, observational, multicentre cohort study including 10 000 patients undergoing major surgery who are subsequently admitted to the ICU or a similar high dependency unit. The primary endpoint is the incidence of AKI within 72 hours after surgery according to the KDIGO criteria. Secondary endpoints include use of renal replacement therapy (RRT), mortality during ICU and hospital stay, length of ICU and hospital stay and major adverse kidney events (combined endpoint consisting of persistent renal dysfunction, RRT and mortality) at day 90. Further, we will evaluate preoperative and intraoperative risk factors affecting the incidence of postoperative AKI. In an add-on analysis, we will assess urinary biomarkers for early detection of AKI. EPIS-AKI has been approved by the leading Ethics Committee of the Medical Council North Rhine-Westphalia, of the Westphalian Wilhelms-University Münster and the corresponding Ethics Committee at each participating site. Results will be disseminated widely and published in peer-reviewed journals, presented at conferences and used to design further AKI-related trials. Trial registration number NCT04165369

Las anomalías precoces de la continuidad en el discurso constituyen biomarcadores predictivos de psicosis

Language is being systematized as an area of clinical research because it contains features that function as a biomarker for the prediction of psychosis. The aim of the study was to contrast two types of continuity features such as connection, iteration, and referential distance, and, on the other hand, those of verbal fluency, understood as the presence of aberrant pauses. Clinical interviews of 10 patients diagnosed with schizophrenia, 10 CHR and 10 healthy controls were analyzed. For the analysis of referentiality, sentence windows were selected and for verbal fluency, 15 minutes of speech were considered. The results suggest the presence of abnormalities in referentiality and verbal fluency among the CHR population. These similarities are found in terms of occurrence and similarity to those of the schizophrenia group, which supports our hypothesis that they are predictive biomarkers.El lenguaje se está sistematizando como área de pesquisa clínica porque contiene características que funcionan como un biomarcador para la predicción de psicosis. El objetivo del estudio fue contrastar dos tipos de características de continuidad discursiva entre personas que cursan Estados Mentales de Alto Riesgo (CHR) y personas con diagnóstico de esquizofrenia. Nos referimos, por una parte, a características referenciales, tales como conexión, iteración y distancia referencial, y, por otra, a las de fluidez verbal, entendida como la presencia de pausas aberrantes. Se analizaron entrevistas clínicas de 10 pacientes diagnosticados de esquizofrenia, 10 CHR y 10 controles sanos. Para el análisis de la referencialidad se seleccionaron ventanas de oraciones y para la fluidez verbal se consideraron 15 minutos de habla. Los resultados apuntan a que existe presencia de anomalías en referencialidad y en fluidez verbal entre la población CHR. Dichas similitudes se dan en cuanto a ocurrencia y similitud respecto a las del grupo con esquizofrenia, lo que refrenda nuestra hipótesis de que constituyen biomarcadores predictivos.