Emergent Ferroelectric Switching Behavior from Polar Vortex Lattice.

Topologically protected polar textures have provided a rich playground for the exploration of novel, emergent phenomena. Recent discoveries indicate that ferroelectric vortices and skyrmions not only host properties markedly different from traditional ferroelectrics, but also that these properties can be harnessed for unique memory devices. Using a combination of capacitor-based capacitance measurements and computational models, it is demonstrated that polar vortices in dielectric-ferroelectric-dielectric trilayers exhibit classical ferroelectric bi-stability together with the existence of low-field metastable polarization states. This behavior is directly tied to the in-plane vortex ordering, and it is shown that it can be used as a new method of non-destructive readout-out of the poled state.

Nonvolatile Electric Field Control of Thermal Magnons in the Absence of an Applied Magnetic Field.

Spin transport through magnetic insulators has been demonstrated in a variety of materials and is an emerging pathway for next-generation spin-based computing. To modulate spin transport in these systems, one typically applies a sufficiently strong magnetic field to allow for deterministic control of magnetic order. Here, we make use of the well-known multiferroic magnetoelectric, BiFeO_{3}, to demonstrate nonvolatile, hysteretic, electric-field control of thermally excited magnon current in the absence of an applied magnetic field. These findings are an important step toward magnon-based devices, where electric-field-only control is highly desirable.

Freestanding complex-oxide membranes.

Complex oxides show a vast range of functional responses, unparalleled within the inorganic solids realm, making them promising materials for applications as varied as next-generation field-effect transistors, spintronic devices, electro-optic modulators, pyroelectric detectors, or oxygen reduction catalysts. Their stability in ambient conditions, chemical versatility, and large susceptibility to minute structural and electronic modifications make them ideal subjects of study to discover emergent phenomena and to generate novel functionalities for next-generation devices. Recent advances in the synthesis of single-crystal, freestanding complex oxide membranes provide an unprecedented opportunity to study these materials in a nearly-ideal system (e.g. free of mechanical/thermal interaction with substrates) as well as expanding the range of tools for tweaking their order parameters (i.e. (anti-)ferromagnetic, (anti-)ferroelectric, ferroelastic), and increasing the possibility of achieving novel heterointegration approaches (including interfacing dissimilar materials) by avoiding the chemical, structural, or thermal constraints in synthesis processes. Here, we review the recent developments in the fabrication and characterization of complex-oxide membranes and discuss their potential for unraveling novel physicochemical phenomena at the nanoscale and for further exploiting their functionalities in technologically relevant devices.

The role of lattice dynamics in ferroelectric switching.

Reducing the switching energy of ferroelectric thin films remains an important goal in the pursuit of ultralow-power ferroelectric memory and logic devices. Here, we elucidate the fundamental role of lattice dynamics in ferroelectric switching by studying both freestanding bismuth ferrite (BiFeO3) membranes and films clamped to a substrate. We observe a distinct evolution of the ferroelectric domain pattern, from striped, 71° ferroelastic domains (spacing of ~100 nm) in clamped BiFeO3 films, to large (10's of micrometers) 180° domains in freestanding films. By removing the constraints imposed by mechanical clamping from the substrate, we can realize a ~40% reduction of the switching voltage and a consequent ~60% improvement in the switching speed. Our findings highlight the importance of a dynamic clamping process occurring during switching, which impacts strain, ferroelectric, and ferrodistortive order parameters and plays a critical role in setting the energetics and dynamics of ferroelectric switching.

Thin-Film Ferroelectrics.

Over the last 30 years, the study of ferroelectric oxides has been revolutionized by the implementation of epitaxial-thin-film-based studies, which have driven many advances in the understanding of ferroelectric physics and the realization of novel polar structures and functionalities. New questions have motivated the development of advanced synthesis, characterization, and simulations of epitaxial thin films and, in turn, have provided new insights and applications across the micro-, meso-, and macroscopic length scales. This review traces the evolution of ferroelectric thin-film research through the early days developing understanding of the roles of size and strain on ferroelectrics to the present day, where such understanding is used to create complex hierarchical domain structures, novel polar topologies, and controlled chemical and defect profiles. The extension of epitaxial techniques, coupled with advances in high-throughput simulations, now stands to accelerate the discovery and study of new ferroelectric materials. Coming hand-in-hand with these new materials is new understanding and control of ferroelectric functionalities. Today, researchers are actively working to apply these lessons in a number of applications, including novel memory and logic architectures, as well as a host of energy conversion devices.

Ferroelectricity in a semiconducting all-inorganic halide perovskite.

Ferroelectric semiconductors are rare materials with both spontaneous polarizations and visible light absorptions that are promising for designing functional photoferroelectrics, such as optical switches and ferroelectric photovoltaics. The emerging halide perovskites with remarkable semiconducting properties also have the potential of being ferroelectric, yet the evidence of robust ferroelectricity in the typical three-dimensional hybrid halide perovskites has been elusive. Here, we report on the investigation of ferroelectricity in all-inorganic halide perovskites, CsGeX3, with bandgaps of 1.6 to 3.3 eV. Their ferroelectricity originates from the lone pair stereochemical activity in Ge (II) that promotes the ion displacement. This gives rise to their spontaneous polarizations of ~10 to 20 µC/cm2, evidenced by both ab initio calculations and key experiments including atomic-level ionic displacement vector mapping and ferroelectric hysteresis loop measurement. Furthermore, characteristic ferroelectric domain patterns on the well-defined CsGeBr3 nanoplates are imaged with both piezo-response force microscopy and nonlinear optical microscopic method.

Exploring the Pb1- x Srx HfO3 System and Potential for High Capacitive Energy Storage Density and Efficiency.

The hafnate perovskites PbHfO3 (antiferroelectric) and SrHfO3 ("potential" ferroelectric) are studied as epitaxial thin films on SrTiO3 (001) substrates with the added opportunity of observing a morphotropic phase boundary (MPB) in the Pb1- x Srx HfO3 system. The resulting (240)-oriented PbHfO3 (Pba2) films exhibited antiferroelectric switching with a saturation polarization ≈53 µC cm-2 at 1.6 MV cm-1 , weak-field dielectric constant ≈186 at 298 K, and an antiferroelectric-to-paraelectric phase transition at ≈518 K. (002)-oriented SrHfO3 films exhibited neither ferroelectric behavior nor evidence of a polar P4mm phase . Instead, the SrHfO3 films exhibited a weak-field dielectric constant ≈25 at 298 K and no signs of a structural transition to a polar phase as a function of temperature (77-623 K) and electric field (-3 to 3 MV cm-1 ). While the lack of ferroelectric order in SrHfO3 removes the potential for MPB, structural and property evolution of the Pb1- x Srx HfO3 (0 ≤ x < 1) system is explored. Strontium alloying increased the electric-breakdown strength (EB ) and decreased hysteresis loss, thus enhancing the capacitive energy storage density (Ur ) and efficiency (η). The composition, Pb0.5 Sr0.5 HfO3 produced the best combination of EB  = 5.12 ± 0.5 MV cm-1 , Ur  = 77 ± 5 J cm-3 , and η = 97 ± 2%, well out-performing PbHfO3 and other antiferroelectric oxides.

Manejo del dolor en plástica de ligamento cruzado anterior. Bloqueo del nervio safeno interno. Estudio comparativo / Pain management in anterior cruciate ligament reconstruction. Saphenous Nerve block. Comparative study

Introducción: El manejo del dolor postoperatorio en pacientes que recibieron una reconstrucción del ligamento cruzado anterior (LCA) debe ser incluido como objetivo fundamental de toda estrategia quirúrgica. El bloqueo selectivo del nervio safeno interno mediante asistencia ecográfica se presenta como una alternativa eficaz para el control del dolor sin afectar la actividad motora del cuádriceps. El propósito de este estudio fue comparar el dolor postoperatorio en pacientes que recibieron una reconstrucción del LCA con injerto autólogo hueso-tendón-hueso (H-T-H), asistidos con anestesia raquídea, analgesia multimodal más bloqueo selectivo del nervio safeno interno versus pacientes que recibieron anestesia raquídea y analgesia multimodal. Materiales y métodos: se realizó un ensayo clínico no aleatorizado de pacientes consecutivos, comparados en dos grupos de trabajo según tipo de estrategia anestésica utilizada: treinta y seis pacientes en grupo 1 y cuarenta en el grupo 2. El promedio de edad fue de veintinueve años (20­42) en el grupo 1 y de treinta y dos años (18­49) en el grupo 2.Resultados: se encontraron diferencias estadísticamente significativas entre los valores promedio en la escala numérica verbal (ENV), se evidencian menores registros y mejor evolución de dolor en pacientes del grupo 1. También se hallaron diferencias estadísticamente significativas entre los niveles de satisfacción con el tratamiento del dolor a favor del grupo 1. Conclusión: el bloqueo selectivo del nervio safeno interno, asociado a la anestesia raquídea y a un esquema adecuado de analgesia multimodal, provee un excelente control del dolor y permite una externación rápida con alto grado de satisfacción en pacientes que recibieron una reconstrucción artroscópica del LCA con injerto H-T-H autólogo.

Introduction: Postoperative pain management in patients who underwent anterior cruciate ligament (ACL) reconstruction should be included as a fundamental objective of any surgical strategy. The internal Saphenous Nerve block with ultrasound assistance is presented as an effective strategy for pain control without affecting quadriceps motor activity. The aim of this study is to compare the postoperative pain management in patients who have received an arthroscopic autologous Bone Tendon Bone (BTB) ACL reconstruction, using spinal anesthesia, selective internal saphenous nerve block, and multimodal analgesia scheme versus patients who received spinal anesthesia and same multimodal analgesia scheme. Materials and methods: we performed a non randomized controlled trial, of two prospective series of patients by anesthetic strategy used: thirty-six patients in Group 1 and forty patients in Group 2. The average age by groups was twenty-nine years (range 20­42) in Group 1 and thirty-two years (18­49) in Group 2.Results: statistically significant differences were found between the average pain values reported by Numeric Rating Scale (NRS) in two groups, showing lower pain records in Group I, as well in the evolution of pain in favor of Group I. Statistically significant differences were found between the mean levels of satisfaction with pain treatment. Conclusion: in ACL reconstruction using BTB autologous graft, selective internal saphenous nerve block, with spinal anesthesia associated an adequate multimodal analgesia scheme, provides excellent pain control, allowing rapid hospital discharge with a high level of satisfaction

Correlating Surface Crystal Orientation and Gas Kinetics in Perovskite Oxide Electrodes.

Solid-gas interactions at electrode surfaces determine the efficiency of solid-oxide fuel cells and electrolyzers. Here, the correlation between surface-gas kinetics and the crystal orientation of perovskite electrodes is studied in the model system La0.8 Sr0.2 Co0.2 Fe0.8 O3 . The gas-exchange kinetics are characterized by synthesizing epitaxial half-cell geometries where three single-variant surfaces are produced [i.e., La0.8 Sr0.2 Co0.2 Fe0.8 O3 /La0.9 Sr0.1 Ga0.95 Mg0.05 O3-δ /SrRuO3 /SrTiO3 (001), (110), and (111)]. Electrochemical impedance spectroscopy and electrical conductivity relaxation measurements reveal a strong surface-orientation dependency of the gas-exchange kinetics, wherein (111)-oriented surfaces exhibit an activity >3-times higher as compared to (001)-oriented surfaces. Oxygen partial pressure ( p O 2 )-dependent electrochemical impedance spectroscopy studies reveal that while the three surfaces have different gas-exchange kinetics, the reaction mechanisms and rate-limiting steps are the same (i.e., charge-transfer to the diatomic oxygen species). First-principles calculations suggest that the formation energy of vacancies and adsorption at the various surfaces is different and influenced by the surface polarity. Finally, synchrotron-based, ambient-pressure X-ray spectroscopies reveal distinct electronic changes and surface chemistry among the different surface orientations. Taken together, thin-film epitaxy provides an efficient approach to control and understand the electrode reactivity ultimately demonstrating that the (111)-surface exhibits a high density of active surface sites which leads to higher activity.

Conocimientos básicos y percepciones en cuidados paliativos en médicos de pregrado de la Universidad Nacional Autónoma de México: un estudio transversal / Basic knowledge and perceptions of palliative care among undergraduate physicians at the National Autonomous University of Mexico: a cross-sectional study

ANTECEDENTES Y OBJETIVO: La OMS considera que, para la integración exitosa de los cuidados paliativos (CP) a la sociedad, es necesaria la educación de los profesionales de la salud y la población en general. Sin embargo, es escasa la información sobre conocimientos de los estudiantes de pregrado de medicina en CP. Este estudio explora el nivel de conocimientos y capacidades de estudiantes de pregrado de medicina para afrontar situaciones al final de la vida de sus pacientes. MATERIALES Y MÉTODOS: Estudio transversal en estudiantes entre enero y febrero de 2015. Se evaluaron los conocimientos básicos y las percepciones sobre la atención de pacientes al final de la vida, en estudiantes de medicina de pregrado utilizando un cuestionario anónimo. El análisis estadístico fue descriptivo y bivariado. RESULTADOS: Se incluyeron 726 participantes con una tasa de respuesta de 82,5 %. La mayoría mujeres (60,8 %), con una mediana de edad de 24 años (23-25). Los CP se definieron como "calidad de vida" en 38,6 % (n = 280). El 63,4 % consideró no ser capaz de manejar el paciente al final de la vida y el 78,4 % se sintió moderadamente capaz de dar malas noticias; el 65,7 % no tuvo entrenamiento en CP y el 88,2 % consideró necesario incluir esta materia en su programa de estudios. CONCLUSIONES: Los resultados muestran algunas necesidades en el área de CP en estudiantes de pregrado de medicina y baja autopercepción de capacidades para afrontar situaciones al final de la vida de los pacientes, así como el interés de incluir la asignatura obligatoria de CP

BACKGROUND AND OBJECTIVE: The WHO considers that, for a successful integration of PC in society, education of health professionals and the general population is necessary. However, information on the knowledge undergraduate medical students have on PC is scarce. This study explores the level of knowledge and skills of medical undergraduate students to face situations at the end of their patients' lives. MATERIALS AND METHODS: A cross-sectional study in Mexican students between January and February 2015. The basic knowledge and perceptions of patient care at the end of life were evaluated in undergraduate medical students using an anonymous questionnaire. The statistical analysis was descriptive and bivariate. RESULTS: A total of 726 participants were included with a response rate of 82.5 %. The majority were women (60.8 %), with a median age of 24 years (23-25). PC was defined as "quality of life" by 38.6 % (n = 280), 63.4 % considered themselves unable to handle patients at the end of life, and 78.4 % felt moderately capable of breaking bad news; 65.7 % had no training in PC and 88.2 % considered it necessary to include this subject in their curriculum. CONCLUSIONS: The results reveal important unsatisfied needs in the area of PC among medical undergraduate students, and a low self-perception of their abilities to face situations at the end of a patient's life, as well as the interest of including CP as a compulsory subject

Epitaxial Strain Control of Relaxor Ferroelectric Phase Evolution.

Understanding and ultimately controlling the large electromechanical effects in relaxor ferroelectrics requires intimate knowledge of how the local-polar order evolves under applied stimuli. Here, the biaxial-strain-induced evolution of and correlations between polar structures and properties in epitaxial films of the prototypical relaxor ferroelectric 0.68PbMg1/3 Nb2/3 O3 -0.32PbTiO3 are investigated. X-ray diffuse-scattering studies reveal an evolution from a butterfly- to disc-shaped pattern and an increase in the correlation-length from ≈8 to ≈25 nm with increasing compressive strain. Molecular-dynamics simulations reveal the origin of the changes in the diffuse-scattering patterns and that strain induces polarization rotation and the merging of the polar order. As the magnitude of the strain is increased, relaxor behavior is gradually suppressed but is not fully quenched. Analysis of the dynamic evolution of dipole alignment in the simulations reveals that, while, for most unit-cell chemistries and configurations, strain drives a tendency toward more ferroelectric-like order, there are certain unit cells that become more disordered under strain, resulting in stronger competition between ordered and disordered regions and enhanced overall susceptibilities. Ultimately, this implies that deterministic creation of specific local chemical configurations could be an effective way to enhance relaxor performance.

Importancia del cepillado bronquial a ciegas en lesiones tumorales periféricas no visibles endoscópicamente / Importance of blind bronchial brushing in peripheral endoscopically non visible lesions

Introducción: el diagnóstico rápido de las enfermedades neoplásicas pulmonares, primarias o metastásica, tiene una influencia importante sobre el resultado del tratamiento y el pronóstico de este grupo de enfermedades con alta letalidad. En el diagnóstico de estas se usan varias técnicas, entre ellas el cepillado bronquial para estudio citológico con el cual se alcanza un gran rendimiento diagnóstico en las lesiones visibles endoscópicamente y que también es de gran utilidad en los tumores periféricos diagnosticados en un porciento significativo y con el mínimo de complicaciones. Objetivo: evaluar los resultados del cepillado bronquial a ciegas en lesiones pulmonares periféricas de posible etiología tumoral. Métodos: estudio descriptivo, de corte transversal retrospectivo, en pacientes a los que se les realizó cepillado bronquial a ciegas en lesiones pulmonares periféricas sugestivas de ser tumorales en el servicio de neumología del Hospital Hermanos Ameijeiras, en un periodo de 10 años. Se tomaron en cuenta variables como: la localización de la lesión, cepillado útil para diagnóstico, positivo y negativo, tamaño de la lesión y los diagnósticos definitivos. Resultados: se realizó cepillado a ciegas a 517 pacientes, fue útil para diagnóstico en 491 (95 por ciento), en 289 (56 por ciento) se obtuvo resultado positivo. Conclusiones: el cepillado a ciegas en lesiones pulmonares periféricas tumorales es una técnica que mejora considerablemente el rendimiento diagnóstico del carcinoma broncógeno con un número bajo de complicaciones(AU)

Introduction: The rapid diagnosis of pulmonary, primary or metastatic neoplastic diseases has significant influence on the outcome of treatment and the prognosis of this group of high lethal diseases. In their diagnosis, several techniques are used, among them the bronchial brushing for cytological study which achieves great diagnostic performance in endoscopically visible lesions and it is also very useful in the peripheral tumors diagnosed in a significant percentage and with minimum complications. Objective: To evaluate the results of blind bronchial brushing in peripheral lung lesions of possible tumor etiology. Methods: A descriptive, retrospective, cross-sectional study in patients who underwent blind bronchial brushing in peripheral pulmonary lesions suggestive of tumor was conducted in the Pneumology Department at Hermanos Ameijeiras Hospital, over a period of 10 years. The variables taken into account were location of the lesion, brushing useful for diagnosis, positive and negative results, size of the lesion, and the definitive diagnoses. Results: Blind brushing was performed on 517 patients, it was useful for diagnosis in 491 (95 percent), a positive result was obtained in 289 (56 percent). Conclusions: Blind brushing technique in peripheral lung lesions considerably improves the diagnostic performance of bronchogenic carcinoma with low number of complications(AU)

Biopsia de pulmón transbroncoscópica / Transbronchoscopic lung biopsy

Introducción: el diagnóstico temprano de las enfermedades que afectan el parénquima pulmonar ya sean malignas o benignas es de vital importancia para disminuir la mortalidad por estas, la cual es elevada. La biopsia de pulmón transbroncoscópica es fundamental en el diagnóstico de dichas enfermedades con una gran efectividad y un mínimo de invasividad. Objetivo: evaluar los resultados de la biopsia de pulmón transbroncoscópica en lesiones parenquimatosas y sus complicaciones. Métodos: se realizó un estudio descriptivo, de corte transversal retrospectivo, en pacientes a los cuales se les efectuó biopsia de pulmón transbroncoscópica en lesiones parenquimatosas, en el servicio de neumología del hospital Hermanos Ameijeiras, en un periodo de 10 años. Se tomaron en cuenta las variables diagnósticos definitivos, el tipo de afectación radiológica, los factores de riesgo y las complicaciones de dicho proceder. Resultados: se realizó biopsias a 154 pacientes, a 51 se le diagnosticó una enfermedad no maligna y a 78 una enfermedad neoplásica. A 25 pacientes con radiografía torácica anormal no se les estableció diagnóstico con esta técnica. Se obtuvo una muestra adecuada en 145 pacientes (94,1 por ciento) con una exactitud diagnóstica del 83,7 por ciento en enfermedad intersticial, maligna e infecciosa pulmonar. El número de complicaciones fue mínimo. Conclusiones: la biopsia de pulmón transbroncoscópica tiene un alto rendimiento diagnóstico con un número bajo de complicaciones(AU)

Introduction: The early diagnosis of diseases that affect the lung parenchyma, whether malignant or benign, is of vital importance to reduce mortality, which is high. Transbronchoscopic lung biopsy is fundamental in the diagnosis of these diseases since it is highly effective and least invasive. Objective: To evaluate the results of transbronchoscopic lung biopsy in parenchymal lesions and their complications. Methods: A descriptive, retrospective, cross-sectional study was conducted in patients who underwent transbronchoscopic lung biopsy in parenchymal lesions at Hermanos Ameijeiras Hospital Pneumology department, over 10 years. The definitive diagnoses, the type of radiological affectation, the risk factors and the complications of said procedure were taken into account as variables. Results: 154 patients were biopsied, 51 were diagnosed with a non-malignant disease and 78 with a neoplastic disease. Twenty-five patients with abnormal chest radiography were not diagnosed using this technique. An adequate sample was obtained in 145 patients (94.1 percent) with diagnostic accuracy of 83.7 percent in interstitial, malignant and infectious lung disease. The number of complications was minimal. Conclusions: Transbronchoscopic lung biopsy has high diagnostic yield with a low number of complications(AU)