Synthesis and reactivity of N-alkyl-2-oxoalkanesulfonamides

A series of N-alkyl-2-oxoalkanesulfonamides have been synthesized by reacting silyl enol ethers with N-alkyl-sulfamoyl chlorides. Their reactivity towards electrophiles was investigated in order to explore the regio-and stereoselectivity of the process. 2-Oxoalkanesulfonamides were used to prepare 5-(methylsulfamoyl)-1,4-dihydropyridines derivatives

Estudio de pre factibilidad para la creación de una planta procesadora de licor de cacao en la ciudad de Estelí, Nicaragua

Presenta estudio de pre factibilidad para la creación de una planta procesadora de licor de cacao en la ciudad de Estelí en el cual se determinó la oferta y la demanda por medio de un estudio de mercado, así como el diseño de una estructura de planta de la empresa y un estudio económico y financiero con el objetivo de tener la viabilidad del proyecto

Problemario de termodinámica aplicada II

1 archivo PDF (157 páginas) ; 3a ed. 2009El contenido del libro tiene como objeto auxiliar a los alumnos en el curso de termodinámica, para ello se expone la teoria y se plantea una serie de problemas

Metodología de diseño, observación y cálculo de redes geodésicas interiores en túneles de ferrocarril de alta velocidad

El guiado de las Tuneladoras durante su avance debe apoyarse en los puntos determinados inmediatamente detrás de ellas. Conseguir las precisiones requeridas presentaría algunas dificultades en condiciones normales con respecto al exterior, pero en el interior de un túnel se plantean ciertos factores que ensombrecen el panorama. El más importante y difícil de tratar es el de la refracción lateral. El diseño de redes interiores es uno de los principales problemas, desde el punto de vista geodésico y topográfico, el cual tiene unas características tales que todos los textos de topografía de precisión aconsejan evitar. Con estas redes se va guiando la tuneladora y en ningún momento dicha red vuelve a tener comprobación sobre otros puntos de control. A medida que la red va avanzando, las precisiones obtenidas de sus coordenadas van empeorando de forma exponencial. Este trabajo establece una metodología para el diseño de redes planimétricas interiores. ABSTRACT The guiding of TBMs (Tunnel Boring Machines) along their advance must be based on points placed immediately behind them. Achieving good accuracies results would present some difficulties for normal exterior conditions, but inside a tunnel certain factors clouding the outlook arise. The most important and difficult factor to deal with, has to do with lateral refraction. Internal geodetic networks design is one of the more challenging problems from the geodetic and topographic point of view, as the bibliographical review dealing with this subject, advises to avoid this practice. This network allows only guiding the TBM, so that it is not used for further checking or quality control. As the network progresses, the reached coordinate accuracies deteriorate exponentially. This work establishes a methodology for the design of internal horizontal networks

Manejo laparoscópico de las hernias ventrales mediante abordaje totalmente extraperitoneal (eTEP): experiencia inicial y resultados a corto plazo

Introduction. Managing ventral hernia remains a challenge for surgeons. Repairing it using minimally invasive techniques, such as laparoscopic totally extraperitoneal (eTEP), which allows for a wide dissection of the space to be repaired, faster postoperative recovery, less postoperative pain and shorter hospital stay. The eTEP approach is a novel technique that focus on the uses of the retromuscular space to place prosthetic material and strengthen the abdominal wall. The objective is to describe the short-term results of our initial experience with the eTEP technique in the management of ventral hernias. Methodology. Observational, descriptive, retrospective, study, which included patients with a diagnosis of ventral hernia, undergoing laparoscopic eTEP surgery, between July-2021 and June-2022. Results. Of a total of 21 patients, 61.9% were men. 47.6% were overweight and 52.4% were obese. Average hospital stay: 1.6 days. 66.7% were incisional hernias. The surgical techniques performed were: Rives-Stoppa (71.4%) with associated transversus abdominis muscle release in 28.6%. 19% of the patients presented global complications and only one was severe, requiring surgical reintervention. The presence of clinical seroma was observed in 9.5% and ultrasound in 57.1%. There was no evidence of hematomas, surgical wound infection or cases of hernia recurrence. Discussion and conclusions. The laparoscopic-eTEP Rives-Stoppa approach, associated or not with posterior separation of components, in the management of ventral hernias offers good results with a low incidence of postoperative complications, short hospital stay, low incidence of hernia recurrences, so it could be considered a safe and effective technique in the treatment of ventral hernias.Introducción. El manejo de la hernia ventral sigue siendo un desafío para los cirujanos. Su reparación mediante técnicas mínimamente invasivas, como la totalmente extraperitoneal (eTEP) laparoscópica, permite una amplia disección del espacio a reparar, una recuperación postoperatoria más rápida, menor dolor postoperatorio y estancia hospitalaria. El abordaje eTEP es un enfoque novedoso que utiliza el espacio retromuscular para colocar material protésico y fortalecer la pared abdominal. El objetivo es describir los resultados a corto plazo de nuestra experiencia inicial con la técnica eTEP en el manejo de las hernias ventrales. Metodología. Estudio observacional, descriptivo, retrospectivo, donde se incluyen pacientes con el diagnóstico de hernia ventral, sometidos a cirugía laparoscópica-eTEP, entre julio-2021 y junio-2022. Resultados. De un total de 21 pacientes, el 61.9% fueron hombres. El 47.6% tenían sobrepeso y el 52.4% obesidad. Estancia hospitalaria media: 1.6 días. El 66.7% fueron hernias incisionales. Las técnicas quirúrgicas realizadas fueron: Rives-Stoppa (71.4%) asociándose liberación del músculo transverso en el 28.6%. El 19% de los pacientes presentaron complicaciones globales y solo uno fue grave, requiriendo reintervención quirúrgica. Se observó la presencia de seroma clínico en el 9.5% y ecográfico en 57.1%. No se evidenciaron hematomas, infección de herida quirúrgica ni casos de recidiva herniaria. Discusión y conclusiones. El abordaje laparoscópico eTEP Rives-Stoppa, asociado o no a separación posterior de componentes, en el manejo de las hernias ventrales ofrece buenos resultados asociando una baja incidencia de complicaciones postoperatorias, corta estancia hospitalaria, baja incidencia de recidivas herniarias, por lo que podría considerarse una técnica segura y efectiva en el tratamiento de las hernias ventrales

Low-voltage tunable pseudo-differential transconductor with high linearity

A novel tunable transconductor is presented. Input transistors operate in the triode region to achieve programmable voltage-to-current conversion. These transistors are kept in the triode region by a novel negative feedback loop which features simplicity, low voltage requirements, and high output resistance. A linearity analysis is carried out which demonstrates how the proposed transconductance tuning scheme leads to high linearity in a wide transconductance range. Measurement results for a 0.5 μm CMOS implementation of the transconductor show a transconductance tuning range of more than a decade (15 μA/V to 165 μA/V) and a total harmonic distortion of −67 dB at 1 MHz for an input of 1 Vpp and a supply voltage of 1.8 V

Invocació explícita versus invocació implícita: anàlisi comparativa de dos enfocaments de disseny de sistemes d'informació

The main goal of this work is to develop an initial characterization of an information systems design approach that we call implicit invocation and to analyse its potential advantatges and disadvantatges with respect to the conventional approach that we call explicit invocation. Our work tries to contribute to this approach at the specific field of object oriented design of information systems. In our analysis we use an example that consist in some simplified banking operations, that we use as basis for the comparation of the alternative designs we explore. We characterize what could be implicit invocation in information systems design, we apply this characterization to the example, and we present a comparative analysis of the two designs.Postprint (published version

Influence of Structure-modifying Agents in the Synthesis of Zr-doped SBA-15 Silica and Their Use as Catalysts in the Furfural Hydrogenation to Obtain High Value-added Products through the Meerwein-Ponndorf-Verley Reduction

Zr-doped mesoporous silicas with different textural parameters have been synthesized in the presence of structure-modifying agents, and then characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption at -196 ºC, NH3 thermoprogrammed desorption (NH3–TPD), CO2 thermoprogrammed desorption (CO2–TPD), and X-ray photoelectron spectroscopy (XPS). These porous materials were evaluated in the furfural hydrogenation through the Meerwein-Ponndorf-Verley (MPV) reaction. The catalytic results indicate that the catalyst synthesized under hydrothermal conditions and adding a pore expander agent is more active and selective to furfuryl alcohol. However, the Zr-doped porous silica catalysts that were synthesized at room temperature, which possess narrow pore sizes, tend to form i-propyl furfuryland difurfuryl ethers, coming from etherification between furfuryl alcohol (FOL) and isopropanol molecules (used as H-donor) by a SN2 mechanism.This research was funded by the Ministry of Economy and Competitiveness (Spain) (grant numbers: CTQ2015-64226-C3-3-R, IEDI-2016-00743), Junta de Andalucía (Spain) (P12-RNM-1565), and FEDER (European Union) funds

Effect of the chromaticity of stimuli on night vision disturbances

The perception of halos and other night vision disturbances is a common complaint in clinical practice. Such visual disturbances must be assessed in order to fully characterize each patient’s visual performance, which is particularly relevant when carrying out a range of daily tasks. Visual problems are usually assessed using achromatic stimuli, yet the stimuli encountered in daily life have very different chromaticities. Hence, it is important to assess the effect of the chromaticity of visual stimuli on night vision disturbances. The aim of this work is to study the influence of the chromaticity of different visual stimuli on night vision disturbances by analyzing straylight and visual discrimination under low-light conditions. For that, we assessed the monocular and binocular visual discrimination of 27 subjects under low illumination using the Halo test. The subjects’ visual discrimination was assessed after exposure to different visual stimuli: achromatic, red, green, and blue, both at the monitor’s maximum luminance and maintaining the same luminance value for the different visual stimuli. Monocular straylight was also measured for an achromatic, red, green, and blue stimuli. The blue stimulus had the greatest effect on halos in both monocular and binocular conditions. Visual discrimination was similar for the red, green, and achromatic stimuli, but worsened at lower luminance. The greatest influence of straylight was observed for the blue stimulus. In addition, visual discrimination correlated with straylight measurements for achromatic stimuli, wherein greater straylight values correlated with an increased perception of halos and other visual disturbances.- Proyecto A-FQM-532-UGR20, financiado por FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades - Proyecto PID2020-115184RB-I00, financiado por MCIN/AEI/10.13039/50110001103

A low-pass filter with automatic frequency tuning for a bluetooth receiver

A third-order Gm-C Chebyshev low-pass filter with high linearity and automatic frequency programmability has been designed. The filter is intended to be used as a channel-select filter for a zero-IF Bluetooth receiver. The frequency tuning scheme is simpler and has more relaxed specifications than conventional ones. The filter bandwidth is 0.5 MHz and the overall scheme dissipates 1.1 mA from a 1.8-V supply. The third-order intermodulation (IM3) distortion of the filter for a 1Vpp two-tone signal centered at 350 kHz is −67dB