Ionic-Liquid Gating in Two-Dimensional TMDs: The Operation Principles and Spectroscopic Capabilities.

Ionic-liquid gating (ILG) is able to enhance carrier densities well above the achievable values in traditional field-effect transistors (FETs), revealing it to be a promising technique for exploring the electronic phases of materials in extreme doping regimes. Due to their chemical stability, transition metal dichalcogenides (TMDs) are ideal candidates to produce ionic-liquid-gated FETs. Furthermore, as recently discovered, ILG can be used to obtain the band gap of two-dimensional semiconductors directly from the simple transfer characteristics. In this work, we present an overview of the operation principles of ionic liquid gating in TMD-based transistors, establishing the importance of the reference voltage to obtain hysteresis-free transfer characteristics, and hence, precisely determine the band gap. We produced ILG-based bilayer WSe2 FETs and demonstrated their ambipolar behavior. We estimated the band gap directly from the transfer characteristics, demonstrating the potential of ILG as a spectroscopy technique.

Strongyloides stercoralis: a rare and severe presentation in a pregnant woman.

Strongyloides stercoralis is a parasitic nematode with a worldwide distribution. It can go from an asymptomatic infection to a life-threatening hyperinfection syndrome. Here, we report a case of intestinal obstruction due to S. stercoralis in a pregnant woman. This condition, as well as severe strongyloidiasis in pregnant women, is seldomly reported. In this case, Human T-lymphotropic Virus 1 (HTLV-1) coinfection was confirmed, a well-known risk factor for a more severe presentation of strongyloidiasis. We suggest that HTLV status should be screened in every severe S. stercoralis infection, or when, despite a correct treatment, a relapse is observed.

Diagnóstico y tratamiento histeroscópico de una paciente posmenopáusica con fístula arteriovenosa uterina / Hysteroscopy diagnosis and management of uterine arterio-venous fistula in a postmenopausal woman

Resumen ANTECEDENTES: La fístula arteriovenosa uterina es una de las malformaciones vasculares más frecuentes. El sangrado vaginal abundante es un signo sugerente de este tipo de alteración. CASO CLÍNICO: Paciente de 51 años, acudió al servicio de Urgencias debido a un sangrado vaginal abundante de un mes de evolución. En la exploración física se objetivaron los genitales externos y la vagina normales, y el útero ligeramente aumentado de tamaño. La ecografía transvaginal con Doppler color solo reportó aumento de la vascularización uterina. La histeroscopia diagnóstica confirmó la coexistencia de una fístula arteriovenosa uterina. La histeroscopia quirúrgica se practicó con espéculo, pinza de Pozzi, dilatación con tallos de Hegar (9'5), coagulación con histeroscopio Storz, asa de Collins, con energía bipolar a 45 watt y suero fisiológico como medio de distensión. La malformación arteriovenosa se coaguló en diversas zonas anatómicas, hasta conseguir la obstrucción completa de la fístula. El posoperatorio trascurrió sin contratiempos. El seguimiento de la paciente fue satisfactorio, hasta la fecha no manifiesta síntomas adicionales de la alteración. CONCLUSIONES: La histeroscopia es un método efectivo, de mínima invasión y con escasa morbilidad para establecer el diagnóstico y tratamiento de las malformaciones vasculares uterinas.

Abstract BACKGROUND: Uterine arterio-venous fistula is one of the most frequent vascular malformations. A heavy vaginal bleeding should make us suspect the presence of this type of vascular malformation. CLINICAL CASE: A 51-years-old patient was admitted in Emergency Service for heavy vaginal bleeding of one month of evolution. On physical examination, external genitalia and vagina were normal but uterus had slightly increased in size. A transvaginal ultrasound with color Doppler was performed where an increase in uterine vascularization was shown. Subsequently, an office hysteroscopy was carried out confirming the diagnosis of uterine arterio-venous fistula. After a correct anesthetic evaluation, a surgical hysteroscopy was performed, using speculum, Pozzi clamp, dilation with Hegar stems up to number 9.5, coagulation resectoscope Storz Gyrus with Collins loop handle with bipolar energy at 45 watt of coagulation and physiological saline, as a means of relaxation. The arterio-venous malformation was coagulated at several levels until the obliteration of the fistula was completed. The postoperative period was favorable. In the subsequent follow-up in consultation, the patient continues asymptomatic. CONCLUSION: Hysteroscopy is an effective, minimally invasive method with low morbidity to establish the diagnosis and treatment of vascular malformations.

Resonant electron tunnelling assisted by charged domain walls in multiferroic tunnel junctions.

The peculiar features of domain walls observed in ferroelectrics make them promising active elements for next-generation non-volatile memories, logic gates and energy-harvesting devices. Although extensive research activity has been devoted recently to making full use of this technological potential, concrete realizations of working nanodevices exploiting these functional properties are yet to be demonstrated. Here, we fabricate a multiferroic tunnel junction based on ferromagnetic La0.7Sr0.3MnO3 electrodes separated by an ultrathin ferroelectric BaTiO3 tunnel barrier, where a head-to-head domain wall is constrained. An electron gas stabilized by oxygen vacancies is confined within the domain wall, displaying discrete quantum-well energy levels. These states assist resonant electron tunnelling processes across the barrier, leading to strong quantum oscillations of the electrical conductance.

In operando evidence of deoxygenation in ionic liquid gating of YBa2Cu3O7-X.

Field-effect experiments on cuprates using ionic liquids have enabled the exploration of their rich phase diagrams [Leng X, et al. (2011) Phys Rev Lett 107(2):027001]. Conventional understanding of the electrostatic doping is in terms of modifications of the charge density to screen the electric field generated at the double layer. However, it has been recently reported that the suppression of the metal to insulator transition induced in VO2 by ionic liquid gating is due to oxygen vacancy formation rather than to electrostatic doping [Jeong J, et al. (2013) Science 339(6126):1402-1405]. These results underscore the debate on the true nature, electrostatic vs. electrochemical, of the doping of cuprates with ionic liquids. Here, we address the doping mechanism of the high-temperature superconductor YBa2Cu3O7-X (YBCO) by simultaneous ionic liquid gating and X-ray absorption experiments. Pronounced spectral changes are observed at the Cu K-edge concomitant with the superconductor-to-insulator transition, evidencing modification of the Cu coordination resulting from the deoxygenation of the CuO chains, as confirmed by first-principles density functional theory (DFT) simulations. Beyond providing evidence of the importance of chemical doping in electric double-layer (EDL) gating experiments with superconducting cuprates, our work shows that interfacing correlated oxides with ionic liquids enables a delicate control of oxygen content, paving the way to novel electrochemical concepts in future oxide electronics.