Atomic-Scale Mechanisms of MoS2 Oxidation for Kinetic Control of MoS2/MoO3 Interfaces.

Oxidation of transition metal dichalcogenides (TMDs) occurs readily under a variety of conditions. Therefore, understanding the oxidation processes is necessary for successful TMD handling and device fabrication. Here, we investigate atomic-scale oxidation mechanisms of the most widely studied TMD, MoS2. We find that thermal oxidation results in α-phase crystalline MoO3 with sharp interfaces, voids, and crystallographic alignment with the underlying MoS2. Experiments with remote substrates prove that thermal oxidation proceeds via vapor-phase mass transport and redeposition, a challenge to forming thin, conformal films. Oxygen plasma accelerates the kinetics of oxidation relative to the kinetics of mass transport, forming smooth and conformal oxides. The resulting amorphous MoO3 can be grown with subnanometer to several-nanometer thickness, and we calibrate the oxidation rate for different instruments and process parameters. Our results provide quantitative guidance for managing both the atomic scale structure and thin-film morphology of oxides in the design and processing of TMD devices.

Interval gastric cancer: A call to attentiveness and action.

INTRODUCTION AND AIMS: Endoscopy is the most effective method for identifying gastric adenocarcinoma (GAC). Interval gastric cancer (IGC) is GAC that is diagnosed 2-3 years after a normal endoscopy. Its characteristics are unknown in the Colombian environment. The clinical, histopathologic, and endoscopic characteristics were evaluated, along with the presentation rate, proton pump inhibitor (PPI) use, and IGC survival rate, and compared with other types of GAC. METHODS: A retrospective, analytic study was conducted on a prospective cohort. It evaluated 513 patients with GAC treated at our institution, within the time frame of January 2012 and June 2018. The patients had endoscopic diagnosis of GAC and endoscopy within the past three years that was negative for tumor. RESULTS: A total of 513 patients diagnosed with GAC were evaluated. Forty-two of the patients had IGC (8.2%): 9 early lesions and 33 advanced lesions (79%). The IGCs were smaller (31 vs. 41 mm; P < .01), as well as flatter and more depressed (P < .01). There was no association with PPI use, but there was an association with a history of gastrectomy and anastomosis (P = .02), as well as the absence of red flags (P < .003). The most frequent locations were the gastric body (52%) and the antrum (26%). Overall two-year survival was similar between IGC and GAC (37.1 vs. 39.3%, P = .72). CONCLUSION: A total of 8.2% of recently diagnosed GAC were cases of IGC. The presence of anastomosis and the absence of red flags were related to IGC. Overall survival was poor and there were no differences from the other types of GAC detected.

Giant and Controllable Photoplasticity and Photoelasticity in Compound Semiconductors.

We show that the wide-band gap compound semiconductors ZnO, ZnS, and CdS feature large photoplastic and photoelastic effects that are mediated by point defects. We measure the mechanical properties of ceramics and single crystals using nanoindentation, and we find that elasticity and plasticity vary strongly with moderate illumination. For instance, the elastic stiffness of ZnO can increase by greater than 40% due to blue illumination of intensity 1.4 mW/cm^{2}. Above-band-gap illumination (e.g., uv light) has the strongest effect, and the relative effect of subband gap illumination varies between samples-a clear sign of defect-mediated processes. We show giant optomechanical effects can be tuned by materials processing, and that processing dependence can be understood within a framework of point defect equilibrium. The photoplastic effect can be understood by a long-established theory of charged dislocation motion. The photoelastic effect requires a new theoretical framework which we present using density functional theory to study the effect of point defect ionization on local lattice structure and elastic tensors. Our results update the longstanding but lesser-studied field of semiconductor optomechanics, and suggest interesting applications.

Time-resolved photoluminescence studies of perovskite chalcogenides.

Chalcogenides in the perovskite and related crystal structures ("chalcogenide perovskites" for brevity) may be useful for future optoelectronic and energy-conversion technologies inasmuch as they have good excited-state, ambipolar transport properties. In recent years, several studies have suggested that semiconductors in the Ba-Zr-S system have slow non-radiative recombination rates. Here, we present a time-resolved photoluminescence (TRPL) study of excited-state carrier mobility and recombination rates in the perovskite-structured material BaZrS3, and the related Ruddlesden-Popper phase Ba3Zr2S7. We measure state-of-the-art single crystal samples, to identify properties free from the influence of secondary phases and random grain boundaries. We model and fit the data using a semiconductor physics simulation, to enable more direct determination of key material parameters than is possible with empirical data modeling. We find that both materials have Shockley-Read-Hall recombination lifetimes on the order of 50 ns and excited-state diffusion lengths on the order of 5 µm at room temperature, which bodes well for ambipolar device performance in optoelectronic technologies including thin-film solar cells.

CURB-65 as a predictor of 30-day mortality in patients hospitalized with COVID-19 in Ecuador: COVID-EC study.

OBJECTIVE: This article aims to assess the utility of CURB-65 in predicting 30-day mortality in adult patients hospitalized with COVID-19. METHODS: This work is a cohort study conducted between March 1 and April 30, 2020 in Ecuador. RESULTS: A total of 247 patients were included (mean age 60 ± 14 years, 70% men, overall mortality 41.3%). Patients with CURB-65 ≥ 2 had a higher mortality rate (57 vs. 17%, p < .001) that was associated with other markers of risk: advanced age, hypertension, overweight/obesity, kidney failure, hypoxemia, requirement for mechanical ventilation, or onset of respiratory distress. CONCLUSIONS: CURB-65  ≥ 2 was associated with higher 30-day mortality on the univariate (Kaplan-Meier estimator) and multivariate (Cox regression) analysis.

CURB-65 como predictor de mortalidad a 30 días en pacientes hospitalizados con COVID-19 en Ecuador: estudio COVID-EC / CURB-65 as a predictor of 30-day mortality in patients hospitalized with COVID-19 in Ecuador: COVID-EC study

Objetivo: Valorar la utilidad del CURB-65 para predecir la mortalidad a 30 días en pacientes adultos hospitalizados con COVID-19. Métodos: Cohorte realizada entre el 1 de marzo y el 30 de abril de 2020 en Ecuador. Resultados: Se incluyeron 247 pacientes (edad media 60±14 años, 70% varones, mortalidad global 41,3%). Los pacientes con CURB-65≥2 presentaron mayor mortalidad (57 vs. 17%, p<0,001), en asociación con otros marcadores de riesgo: edad avanzada, hipertensión arterial, sobrepeso/obesidad, fracaso renal, hipoxemia, requerimiento de ventilación mecánica o desarrollo de distrés respiratorio.Conclusiones: En el análisis univariado (Kaplan-Meier) y multivariado (regresión de Cox) el CURB-65≥2 se relacionó con una mayor mortalidad a 30 días (AU)

Objective: This article aims to assess the utility of CURB-65 in predicting 30-day mortality in adult patients hospitalized with COVID-19. Methods: This work is a cohort study conducted between March 1 and April 30, 2020 in Ecuador. Results: A total of 247 patients were included (mean age 60±14 years, 70% men, overall mortality 41.3%). Patients with CURB-65≥2 had a higher mortality rate (57 vs. 17%, p<.001) that was associated with other markers of risk: advanced age, hypertension, overweight/obesity, kidney failure, hypoxemia, requirement for mechanical ventilation, or onset of respiratory distress. Conclusions: CURB-65≥2 was associated with higher 30-day mortality on the univariate (Kaplan-Meier estimator) and multivariate (Cox regression) analysis (AU)

[CURB-65 as a predictor of 30-day mortality in patients hospitalized with COVID-19 in Ecuador: COVID-EC study]. / CURB-65 como predictor de mortalidad a 30 días en pacientes hospitalizados con COVID-19 en Ecuador: estudio COVID-EC.

OBJECTIVE: This article aims to assess the utility of CURB-65 in predicting 30-day mortality in adult patients hospitalized with COVID-19. METHODS: This work is a cohort study conducted between March 1 and April 30, 2020 in Ecuador. RESULTS: A total of 247 patients were included (mean age 60 ± 14 years, 70% men, overall mortality 41.3%). Patients with CURB-65 ≥ 2 had a higher mortality rate (57 vs. 17%, p < .001) that was associated with other markers of risk: advanced age, hypertension, overweight/obesity, kidney failure, hypoxemia, requirement for mechanical ventilation, or onset of respiratory distress. CONCLUSIONS: CURB-65 ≥ 2 was associated with higher 30-day mortality on the univariate (Kaplan-Meier estimator) and multivariate (Cox regression) analysis.

Impact of intraoperative colonoscopy on anastomotic leakage detection and prevention in colorectal anastomosis for rectal cancer.

INTRODUCTION AND AIM: The value of leakage testing during colorectal resections to identify anastomotic leaks or bleeding has not been established. Our aim was to compare the impact of intraoperative colonoscopy (IOC) versus insufflation with a syringe, as leakage testing in lower anterior resection (LAR) for rectal cancer, with respect to the incidence of postoperative leakage (PL). MATERIALS AND METHODS: A retrospective study utilizing a prospective database of 426 patients with rectal cancer that underwent elective LAR, within the time frame of January 2015 and December 2019, was conducted. The anastomotic leak test was chosen by the surgeon. The incidence of postoperative leakage was compared between patients that underwent IOC and those that had the syringe leak test, utilizing the logistic regression analysis. Propensity score matching was included. RESULTS: There were no significant differences in the clinical characteristics or morbidity and mortality rates between the two groups. Four patients were excluded, leaving a patient total of 422. Seventy patients with IOC were compared with 352 that had the syringe leak test. The incidence of postoperative leakage was 5.7% in the IOC group and 12.2% in the control group (p = 0.001). After propensity score matching (n = 221), balancing the characteristics between the groups, the incidence of postoperative leakage was 5.7% in the IOC group and 13.9% in the syringe leak test group (p = 0.001). CONCLUSION: IOC was shown to be a safe method for evaluating the integrity of colorectal anastomosis and was associated with a higher percentage of protective stoma use, appearing to reduce the risk for PL.

Growth Kinetics and Atomistic Mechanisms of Native Oxidation of ZrSxSe2-x and MoS2 Crystals.

A thorough understanding of native oxides is essential for designing semiconductor devices. Here, we report a study of the rate and mechanisms of spontaneous oxidation of bulk single crystals of ZrSxSe2-x alloys and MoS2. ZrSxSe2-x alloys oxidize rapidly, and the oxidation rate increases with Se content. Oxidation of basal surfaces is initiated by favorable O2 adsorption and proceeds by a mechanism of Zr-O bond switching, that collapses the van der Waals gaps, and is facilitated by progressive redox transitions of the chalcogen. The rate-limiting process is the formation and out-diffusion of SO2. In contrast, MoS2 basal surfaces are stable due to unfavorable oxygen adsorption. Our results provide insight and quantitative guidance for designing and processing semiconductor devices based on ZrSxSe2-x and MoS2 and identify the atomistic-scale mechanisms of bonding and phase transformations in layered materials with competing anions.

CURB-65 como predictor de mortalidad a 30 días en pacientes hospitalizados con COVID-19 en Ecuador: estudio COVID-EC / CURB-65 as a predictor of 30-day mortality in patients hospitalized with COVID-19 in Ecuador: COVID-EC study

OBJETIVO: Valorar la utilidad del CURB-65 para predecir la mortalidad a 30 días en pacientes adultos hospitalizados con COVID-19. MÉTODOS: Cohorte realizada entre el 1 de marzo y el 30 de abril de 2020 en Ecuador. RESULTADOS: Se incluyeron 247 pacientes (edad media 60 ± 14 años, 70% varones, mortalidad global 41,3%). Los pacientes con CURB-65 ≥ 2 presentaron mayor mortalidad (57 vs. 17%, p < 0,001), en asociación con otros marcadores de riesgo: edad avanzada, hipertensión arterial, sobrepeso/obesidad, fracaso renal, hipoxemia, requerimiento de ventilación mecánica o desarrollo de distrés respiratorio. CONCLUSIONES: En el análisis univariado (Kaplan-Meier) y multivariado (regresión de Cox) el CURB-65 ≥ 2 se relacionó con una mayor mortalidad a 30 días

OBJECTIVE: This article aims to assess the utility of CURB-65 in predicting 30-day mortality in adult patients hospitalized with COVID-19. METHODS: This work is a cohort study conducted between March 1 and April 30, 2020 in Ecuador. RESULTS: A total of 247 patients were included (mean age 60±14 years, 70% men, overall mortality 41.3%). Patients with CURB-65 ≥ 2 had a higher mortality rate (57 vs. 17%, p <.001) that was associated with other markers of risk: advanced age, hypertension, overweight/obesity, kidney failure, hypoxemia, requirement for mechanical ventilation, or onset of respiratory distress. CONCLUSIONS: CURB-65 ≥ 2 was associated with higher 30-day mortality on the univariate (Kaplan-Meier estimator) and multivariate (Cox regression) analysis

Near-infrared photonic phase-change properties of transition metal ditellurides.

We use the (Mo,W)Te2 system to explore the potential of transition metal dichalcogenides (TMDs) as phase-change materials for integrated photonics. We measure the complex optical constant of MoTe2 in both the 2H and 1T' phases by spectroscopic ellipsometry. We find that both phases have large refractive index, which is good for confined light-matter interaction volume. The change Δn between phases is of ℴ(1), which is large and comparable to established phase-change materials. However, both phases have large optical loss, which limits to figure of merit throughout the measured range. We further measure the NIR reflectivity of MoTe2 and Mo0.91W0.09Te2, in both the 2H and 1T' phases. The data show that the strong optical contrast between the 2H and 1T' structures persists even as the thermodynamic barrier between them is reduced by alloying. This bodes well for alloy design of phase-change materials.

Opto-Mechanics Driven Fast Martensitic Transition in Two-Dimensional Materials.

Diffusional phase-change materials, such as Ge-Sb-Te alloys, are used in rewritable nonvolatile memory devices. But the continuous pursuit of readout/write speed and reduced energy consumption in miniaturized devices calls for an optically driven, diffusionless phase change scheme in ultrathin materials. Inspired by optical tweezers, in this work, we illustrate theoretically and computationally that a linearly polarized laser pulse with selected frequency can drive an ultrafast diffusionless martensitic phase transition of two-dimensional ferroelastic materials such as SnO and SnSe monolayers, where the unit-cell strain is tweezed as a generalized coordinate that affects the anisotropic dielectric function and electromagnetic energy density. At laser power of 2.0 × 1010 and 7.7 × 109 W/cm2, the transition potential energy barrier vanishes between two 90°-orientation variants of ferroelastic SnO and SnSe monolayer, respectively, so displacive domain switching can occur within picoseconds. The estimated adiabatic thermal limit of energy input in such optomechanical martensitic transition (OMT) is at least 2 orders of magnitude lower than that in Ge-Sb-Te alloy.

Manejo perioperatorio de los pacientes con dispositivos cardíacos electrónicos implantables / Perioperative management of patients with cardiac implantable electronic devices

Es cada vez más frecuente el uso de dispositivos cardíacos implantables en personas de todas las edades, siendo superlativo en la población adulta mayor, y favoreciendo que cada vez sea más frecuente encontrar pacientes con marcapasos, cardiodesfibriladores o resincronizadores en cirugía por causas no cardíacas. Esta revisión se hizo con el fin de seleccionar y analizar la más actualizada evidencia para el manejo apropiado de los dispositivos cardíacos implantables en el perioperatorio. A través de una exploración detallada en las bases de datos PubMed, Academic Search Complete (EBSCO), ClinicalKey, Cochrane (Ovid), el software de búsqueda UpToDate, libros de texto y patentes de libre acceso al público en Google, seleccionamos 33 monografías que se ajustaban a los objetivos de esta publicación (AU)

The use of implantable cardiac devices in people of all ages is increasing, especially in the elderly population: patients with pacemakers, cardioverter-defibrillators or cardiac resynchronization therapy devices regularly present for surgery for non-cardiac causes. This review was made in order to collect and analyze the latest evidence for the proper management of implantable cardiac devices in the perioperative period. Through a detailed exploration of PubMed, Academic Search Complete (EBSCO), ClinicalKey, Cochrane (Ovid), the search software UpToDate, textbooks and patents freely available to the public on Google, we selected 33 monographs, which matched the objectives of this publication (AU)

Preeclampsia leve y severa: estudio de casos y controles en el Hospital de Chiquinquirá 2012-2014 / Mild and severe preeclampsia: case-control study at the Hospital de Chiquinquirá 2012-2014 / Pré-eclâmpsia leve e severa: estudo de casos e controles no Hospital de Chiquinquirá 2012-2014

La preeclampsia es una de las principales causas de morbimortalidad materna y fetal en Colombia y un problema de salud pública \r\nimportante en la zona de influencia del Hospital Regional de Chiquinquirá (Boyacá, Colombia), pero no se ha cuantificado su \r\nmagnitud ni los factores de riesgo. El objetivo de este estudio analítico fue determinar los factores de riesgo en casos de pree\r\n-\r\nclampsia leve y severa en gestantes atendidas en dicha institución entre 2012 y 2014 para ayudar al diagnóstico temprano, la \r\nvigilancia y la prevención de complicaciones y secuelas. Se realizó un estudio de casos y controles retrospectivo. Se evaluaron 356 \r\nhistorias clínicas, 122 casos y 234 controles. Se realizaron análisis descriptivos, bivariados apoyados por OR con IC 95%, comparación entre grupos a partir de pruebas T-student y U de Mann-Whitney y análisis estratificado por edades. Los resultados: procedencia, \r\nraza, régimen y educación no presentaron asociaciones significativas (p >0,05); antecedentes de preeclampsia, hipertensión arte\r\n-\r\nrial, cesárea en embarazos anteriores, período intergenésico mayor a 10 años e índice de masa corporal al final del embarazo \r\nmayor a 35, son factores de riesgo (p <0,05). Se concluye que el estrato socioeconómico 2 y la raza mestiza son factores protec\r\n-\r\ntores; los análisis estratificados no mostraron confusión por la variable edad; no existe distorsión de la relación entre las variables \r\nantecedentes de preeclampsia, hipertensión, cesáreas anteriores y preeclampsia. Las acciones de intervención para factores de \r\nriesgo en la población de estudio deben dirigirse a los estratos más bajos y población más vulnerable.

Preeclampsia is one of the principle causes of maternal and \r\nfetal morbidity and mortality in Colombia, and it is a major \r\npublic health problem in the area of influence of the Hospital \r\nRegional de Chiquinquirá (Boyacá, Colombia), yet its magni\r\n-\r\ntude and risk factors have not been quantified. The objective \r\nof this analytical study was to determine the risk factors in cases \r\nof mild and severe preeclampsia in pregnant women attended \r\nat the mentioned institution during 2012-2014, to assist in \r\nearly diagnosis, vigilance, and prevention of complications \r\nand sequela. A retrospective study of cases and controls was \r\nperformed. 356 medical records, 122 cases, and 234 controls \r\nwere evaluated. Descriptive, bivariate analyses supported by \r\nan OR with a 95% CI were performed, as were comparison \r\nbetween groups through Student's T-tests and Mann-Whitney \r\nU test and an analysis stratified by age.\r\nResults: Background, race, medical regiment, and education \r\ndidn ́t present significant associations (p >0.05); history of \r\npreeclampsia, hypertension, cesarean in previous pregnan\r\n-\r\ncies, an interpregnancy interval period greater than 10 years, \r\nand a BMI greater than 35 at the end of pregranacy are risk \r\nfactors (p <0.05). It is concluded that the number 2 socioeco\r\n-\r\nnomic stratum and mixed ethnicity are protective factors; \r\nstratified analyzes showed no confounding due to age; there \r\nis no distortion of the relationship between the variables: \r\nhistory of preeclampsia, hypertension, previous cesarean and \r\npreeclampsia. Intervention actions for risk factors in the study \r\npopulation should be directed to the lower strata and to the \r\nmost vulnerable population.

A pré-eclâmpsia é uma das principais causas de morbidade e \r\nmortalidade materna e fetal na Colômbia e é um problema de \r\nsaúde pública importante na zona de influência do Hospital \r\nRegional de Chiquinquirá (Boyacá, Colômbia), mas não tem \r\nsido quantificada sua magnitude nem os fatores de risco. O \r\nobjetivo foi determinar os fatores de risco nos casos de pré-e\r\n-\r\nclâmpsia leve e grave em gestantes atendidas no hospital \r\ndurante 2012-2014, para ajudar ao diagnóstico precoce, vigi\r\n-\r\nlância e prevenção de complicações e sequelas. Realizou-se \r\num estudo de casos e controles retrospectivo. Avaliaram-se \r\n356 prontuários, 122 casos e 234 controles. Realizaram-se \r\nanalises descritivas, bivariadas respaldadas por OR com IC de \r\n95%, os grupos foram comparados usando o teste T-student \r\ne U de Mann-Whitney, além de análise estratificada por idade. \r\nResultados: Origem, raça, sistema de saúde e nível educativo \r\nnão apresentaram associações significantes (p >0,05). Histórico \r\nde pré-eclâmpsia, hipertensão, cesariana na gestação anterior, \r\nperíodo intergenésico maior que 10 anos e IMC no final da \r\ngravidez maior que 35 são fatores de risco (p <0,05). Conclusões: \r\nnível socioeconômico 2 e a raça mestiça são fatores protetores; \r\nas análises estratificadas não mostraram confusão pela variável \r\nidade; não existe distorção da relação entre as variáveis ante\r\n-\r\ncedentes de pré-eclâmpsia, hipertensão, cesáreas anteriores e \r\npré-eclâmpsia. Ações de intervenção para fatores de risco na \r\npopulação estudada devem ser direcionadas para os níveis \r\nsocioeconômicos mais baixos e população mais vulnerável.

Perioperative management of patients with cardiac implantable electronic devices. / Manejo perioperatorio de los pacientes con dispositivos cardíacos electrónicos implantables.

The use of implantable cardiac devices in people of all ages is increasing, especially in the elderly population: patients with pacemakers, cardioverter-defibrillators or cardiac resynchronization therapy devices regularly present for surgery for non-cardiac causes. This review was made in order to collect and analyze the latest evidence for the proper management of implantable cardiac devices in the perioperative period. Through a detailed exploration of PubMed, Academic Search Complete (EBSCO), ClinicalKey, Cochrane (Ovid), the search software UpToDate, textbooks and patents freely available to the public on Google, we selected 33 monographs, which matched the objectives of this publication.

Morfometría nuclear de hepatocitos esteatósicos y esteatósicos estimulados con laser infrarrojo / Nuclear morphometric of the steatotic hepatocytes and stimulated steatotisc with infrared laser

Un total de 24 ratas hembras de 4 meses de vida con peso aproximado de 250 g recibieron una solución de alcohol 40 % disuelto en agua lo cual derivó en una esteatosis alcohólica multivesicular. A 12 de estas ratas esteatósicas se le aplicó estimulaciones de láser infrarrojo con dosis de 8 J/cm2 durante 15 días consecutivos. Posteriormente las ratas fueron sacrificadas y se extrajeron muestras tanto de hígado esteatósico como del estimulado para enseguida ser procesadas para microscopía electrónica de transmisión. De hepatocitos esteatósicos y esteatósicos estimulados se obtuvieron microfotografías electrónicas de transmisión con aumentos finales de 9.500 X, las cuales fueron sometidas a estudios morfométricos para determinar tanto el número de poros nucleares como de fracciones volumétricas de los siguientes componentes celulares: Areas celular y nuclear, fracciones volumétricas de núcleos y nucléolos, eu y heterocromatina. De igual manera se determinó la relación nucleo-citoplasmática de ambos tipos celulares. Del análisis de los resultados entre hepatocitos alcohólicos y alcohólicos estimulados se visualiza que existen notables diferencias en todos los componentes celulares cuantificados. Se concluye que los efectos de la estimulación con lásr infrarrojo provoca en los hepatocitos una drástica transformación en su ultraestructura y en su morfología, situación que se traduciría, por ende, en una variación funcional, representando de esta manera el efecto que dicha estimulación provoca en los hepatocitos.

A total of 24 female rats, aged 4 months and weighing approximately 250 g and they given a solution of 40 % alcohol dissolved in water, leading to alcoholic multivesicular steatosis and 12 of rats was given and infrared laser with dose of 8 J/cm2 during 15 d. The rats were then killed and samples of steatosis and stimulated and were taken and processed for examination by transmission electron microscope. Transmission electron microscope microphotographs steatotic hepatocytes and stimulated steatotic were obtained with final magnification of 9,500 X. They were subjected to morphometric studies to determine the number of nuclear pores and volumetric fractions and areas the following components: cellular and nuclear area, volumetric fractions of nucleus, nucleolus, eu and heterochromatin, nucleocytoplamic ratio of each cell type was determined. Analysis of the results between alcoholic hepatocytes and stimulate alcoholic shows that noticeable differences exist in all the cell components quantified. It is concluded that the effects of the stimuli of laser infrared provoke in the hepatocytes, a drastic transformation of their ultrastructure and morphology. This finally leads to functional variations, representing the effects produced by this stimulate in the hepatocytes.

Poros Nucleares y Función Celular en Epitelio Mamario / Nuclear Pores and Cellular Function

El presente artículo tiene como objetivo central evidenciar la interesante relación que se establece entre la función celular y el número de poros nucleares, relación que modula el activo intercambio nucleo-citoplasmatico en distintas etapas del ciclo celular de la estirpe HC11.

The main objective of this article is related to the study of different existing relationships between cellular function and the number of nuclear pores in order to explain the amount of nuclear-cytoplasmatic exchange through HC11 cell cycle stages.

Sub-Kelvin magnetic and electrical measurements in a diamond anvil cell with in situ tunability.

We discuss techniques for performing continuous measurements across a wide range of pressure-field-temperature phase space, combining the milli-Kelvin temperatures of a helium dilution refrigerator with the giga-Pascal pressures of a diamond anvil cell and the Tesla magnetic fields of a superconducting magnet. With a view towards minimizing remnant magnetic fields and background magnetic susceptibility, we characterize high-strength superalloy materials for the pressure cell assembly, which allows high fidelity measurements of low-field phenomena such as superconductivity below 100 mK at pressures above 10 GPa. In situ tunability and measurement of the pressure permit experiments over a wide range of pressure, while at the same time making possible precise steps across abrupt phase transitions such as those from insulator to metal.

Microscopía electrónica de nucleos hepáticos estimulados con dosis crecientes de laser infrarrojo / Electron microscopy hepatic nuclei stimulated with increasing doses of infrared laser

Un total de 20 ratas hembras de 4 meses de vida con peso aproximado de 250 gramos fueron divididas en 4 grupos de animales rotulados como A, B, C y D. El grupo A corresponde al control y los demás grupos recibieron respectivamente estimulaciones con laser infrarrojo con dosis crecientes de 4, 8 y 16 Joules por cm2 durante 15 días consecutivos en 5 puntos del hígado. Posteriormente las ratas fueron sacrificadas y se extrajeron muestras tanto de hígado control como de los estimulados con inducciones infrarrojas para enseguida ser procesadas para microscopía electrónica de transmisión. De los hepatocitos se obtuvieron microfotografías electrónicas de transmisión con aumentos finales de 9.500 X, las cuales fueron sometidas a estudios morfométricos para determinar fracciones volumétricas de sus núcleos y estructuras nucleares. De igual manera se cuantificaron las áreas nucleares, celulares y se determinó la relación núcleo-citoplasmática de los tipos celulares estudiados. Analizados los resultados entre los hepatocitos controles e irradiados se visualiza que existen notables diferencias en la totalidad de los parámetros cuantificados concluyéndose que los efectos de las estimulaciónes infrarrojas con dosis crecientes genera transformaciones en su ultraestructura y en su morfología, fundamentalmente en el aumento de los volúmenes nucleares, y celulares, los volúmenes de cromatina y de la relación-núcleo-citoplasmática situación que se traduciría en una variación funcional, representando de esta manera un efecto evidente que estas inducciones infrarrojas generan.

Twenty-four four-month-old female rats weighing approximately 250 grams were divided into four groups labeled A, B, C and D. A corresponds to the normal group and the other groups received stimulation increasing doses with 4, 8 and 16 J/cm2 of infrared laser respectively for 15 consecutive days in five points of the liver. The rats were then sacrificed and samples of normal liver and liver stimulated with infrared inductions were extracted for immediate processing via transmission electron microscopy. From cell types transmission electron microphotographs were obtained at magnifications of 9500 X these were subjected to morphometric studies to determine volumetric fractions of the nuclei and nuclear structures. Likewise, cell and nuclear areas and nuclear-citoplasmatic relation were quantified. Analysis of the results between normal and radiated hepatocytes revealed notable differences in all the cell components quantified. It is concluded that the effects of increasing infrared stimulation doses brings transformation in their ultrastructure and morphology, fundamentally in the considerable increase in nuclear volume, chromatin volume and the nuclear-citoplasmatic relation, which ultimately translates into a functional variation, thus representing an obvious impact produced by these infrared inductions.

3.88% efficient tin sulfide solar cells using congruent thermal evaporation.

Tin sulfide (SnS), as a promising absorber material in thin-film photovoltaic devices, is described. Here, it is confirmed that SnS evaporates congruently, which provides facile composition control akin to cadmium telluride. A SnS heterojunction solar cell is demons trated, which has a power conversion efficiency of 3.88% (certified), and an empirical loss analysis is presented to guide further performance improvements.