1,529 research outputs found
Halogenation of SiC for band-gap engineering and excitonic functionalization
The optical excitation spectra and excitonic resonances are investigated in
systematically functionalized SiC with Fluorine and/or Chlorine utilizing
density functional theory in combination with many-body perturbation theory.
The latter is required for a realistic description of the energy band-gaps as
well as for the theoretical realization of excitons. Structural, electronic and
optical properties are scrutinized and show the high stability of the predicted
two-dimensional materials. Their realization in laboratory is thus possible.
Huge band-gaps of the order of 4 eV are found in the so-called GW
approximation, with the occurrence of bright excitons, optically active in the
four investigated materials. Their binding energies vary from 0.9 eV to 1.75 eV
depending on the decoration choice and in one case, a dark exciton is foreseen
to exist in the fully chlorinated SiC. The wide variety of opto-electronic
properties suggest halogenated SiC as interesting materials with potential not
only for solar cell applications, anti-reflection coatings or high-reflective
systems but also for a possible realization of excitonic Bose-Einstein
condensation
El orujo de Physalis peruviana suprime la hipercolesterolemia inducida por una dieta rica en colesterol en ratas
Physalis peruviana (goldenberry) is a promising fruits that can be an ingredient in several functional foods. No reports are available on the effect of the administration of goldenberry pomace on different aspects of the plasma lipid profile in experimental animals. According to the chemical composition of the fruit pomace which includes high levels of bioactive compounds, the hypothesis was that feeding Physalis peruviana pomace may have health-promoting and hypercholesterolemic impacts on rats fed a high cholesterol diet (HCD). Therefore, the objective of this study was to investigate the effect of feeding goldenberry pomace on hypercholesterolemia by analyzing the changes in lipid profiles in HCD fed rats. The chemical composition, lipid profiles (fatty acids, tocopherols and sterols) and phenolic contents of the fruit pomace were determined. Generally, rats fed the fruit pomace showed lower levels of total cholesterol (TC), total triacylglycerol (TAG) and total low density lipoprotein (LDL) cholesterol as well as higher levels of high density lipoprotein (HDL) cholesterol in comparison with animals fed HCD and cholesterol free diets (CFD). Histological examinations of the liver and kidney were also studied. The results demonstrated that goldenberry pomace consumption provides overall beneficial effects on reversing HCD associated detrimental changes.Physalis peruviana (aguaymanto) es un fruto prometedor que puede ser parte de diferentes alimentos funcionales. No hay datos disponibles sobre el efecto de la administración del orujo de aguaymanto sobre diferentes aspectos del perfil de lipídos plasmáticos en animales de experimentación. De acuerdo con la composición química del orujo de la fruta que incluye altos niveles de compuestos bioactivos, se demostró la hipótesis de que la alimentación con orujo de Physalis peruviana puede tener efectos saludables y sobre la hipercolesterolemia en ratas alimentadas con una dieta alta en colesterol (HCD). Por tanto, el objetivo de este estudio fue investigar el efecto de una alimentación con orujo de Physalis peruviana o sobre la hipercolesterolemia analizando los cambios del perfil lipídico en ratas alimentadas con una dieta alta en colesterol (HCD). Se determinó la composición química, el perfil lipídico (ácidos grasos, tocoferoles y esteroles) y contenido fenólico del orujo de aguaymanto. En términos generales, las ratas alimentadas con orujo de aguaymanto mostraron niveles más bajos de colesterol total (TC), triglicéridos totales (TAG) y lipoproteínas de baja densidad totales, así como superiores niveles de lipoproteínas de alta densidad (HDL) en comparación con los animales alimentados con HCD y con una dieta libre de colesterol (CFD). El examen histológico del hígado y de los riñones fue también realizado. Los resultados demostraron que el consumo de orujo de aguaymanto proporciona efectos beneficiosos generales invirtiendo los cambios perjudiciales asociados a una dieta HCD
Transition Metal Catalyzed Reductive Cyclization Reactions of Nitroarenes and Nitroalkenes
Nitroarenes are the entry point for the production of most nitrogen-containing aromatic compounds. Thus, any transformation that leads directly from them to the final product allows saving one or more synthetic steps. This review deals with homogeneously catalyzed reactions leading to the formation of N-heterocyclic compounds from nitroarenes or nitroalkenes in one pot. Reactions that lead to the intermediate formation of amines are not considered. Carbon monoxide is the most often employed reductant because it allows selective reactions, is cheap, and only produces CO2 as stoichiometric byproduct. However, the difficulty in handling pressurized CO has stimulated in recent years the development of CO-surrogates, that is molecules able to liberate CO during the reaction. The use of phosphines and diols has also been developed in conjunction with molybdenum catalysts. The review focusses in more detail on the literature in the period 2006\u20132018, but reference to earlier work is made when necessary to put recent results in a more general context
Perancangan Sistem Pemantauan Surat Izin Praktik Tenaga Kesehatan di Dinas Kesehatan Pringsewu Lampung
The design of monitoring system of health workers' practice license in health office in Pringsewu LampungPurposeThe purpose of this study was to design a prototype of a monitoring system of health practice licenses (SIP) of health workers in Pringsewu's local government. MethodsAn action research was conducted with 15 subjects. Data collection was done through in-depth interviews, observations and focus group discussions.ResultsBy order of priority issues, value urgency showed 70%, seriousness 75% and growth 75%, and the ultrasound matrix (urgency, seriousness and growth) showed that it is necessary to design a prototype monitoring SIP (100%), access to online or offline (66.66%), mapping of health workers (60%), and integration and communication with professional organizations and the Ministry of Health of Indonesia (60%). One of the functional testing systems that can be used is the SIP monitoring system. Furthermore, considering the system functional testing system the results showed 58% strongly agreed and 42% agreed with the use of the SIP designed monitoring system. The evaluation of the feasibility of the system shows that the aspect ratio before and after using the prototype was 5 times faster than before using the system. This system provides a positive effect on employee performance and can simplify management of managerial data licensing health professionals. ConclusionThe designed prototype system for monitoring practice licenses has overcome one of the problems in the regulatory process concerning the licensing of health personnel, although it is not developed fully, but the prototype is enough to give change and improved performance at the district health office in Pringsewu
Synthesis of Carbazoles: Use of Formate Esters as CO Surrogates in the Palladium Catalyzed Reductive Cyclization of 2-Nitrobiphenyls
Palladium complexes with phenanthrolines are so far the most effective catalysts for the reductive cyclization of nitroarenes by carbon monoxide to yield a variety of heterocyclic compounds.[1] Despite the high efficiency and the high atom-economical character of many of these reactions, they have not become of widespread use. This is mainly ascribable to the need for pressurized CO and pressure equipment (including CO safety measures). In the aim of turning this kind of reaction into a as an in situ source of CO. The reaction can be performed in a glass pressure tube, a cheap equipment accessible to every laboratory. Our previous work was mainly focused on the synthesis of indoles by reductive cyclization of o-nitrostyrenes[2] and oxazines by the hetero Diels-Alder condensation of a conjugated diene with a nitrosoarene formed in situ by the reduction of the starting nitroarene.[3] However, the application of the previously developed method to the reductive cyclization of 2-nitrobiphenyls to carbazoles afforded only moderate yields even under harsher conditions and higher catalyst loadings. The result is not totally unexpected since this reductive cyclization is known to be more difficult than the other previously studied. Here we report the results of our investigations on this reaction aimed at both improving the catalytic performance and better understanding the reaction mechanism
Palladium Catalyzed Reductive Cyclization of Nitrobiphenyls Using Formate Esters as CO Surrogates
Palladium complexes with phenanthroline ligands are so far the most effective catalysts for the reductive cyclization of nitroarenes by carbon monoxide to yield a variety of heterocyclic compounds.[1] Despite the high efficiency and the high atom-economical character of many of these reactions, they have not become of widespread use. This is mainly attributed to the need for pressurized CO and pressure equipment (requiring CO safety measures). In the aim of turning this kind of reaction into a \u201cgeneral tool\u201d for the synthetic chemist, we developed a procedure based on the use of phenyl formate as an in situ source of CO. The reaction can be performed in a glass pressure tube, a cheap equipment accessible to every laboratory. Our previous work was mainly focused on the synthesis of indoles by reductive cyclization of o-nitrostyrenes[2] and oxazines by the hetero Diels-Alder condensation of a conjugated diene with a nitrosoarene formed in situ by the reduction of the starting nitroarene.[3] However, the application of the previously developed method to the reductive cyclization of 2-nitrobiphenyls to carbazoles (Scheme 1) afforded only moderate yields even under harsher conditions and higher catalyst loadings. The result is not totally unexpected since this reductive cyclization is known to be more difficult than the other previously studied. Here we report the results of our investigations on this reaction aimed at both improving the catalytic performance and better understanding the reaction mechanism
Perfil lipídico, poder antirradicalario y propiedades antimicrobianas del aceite de Syzygium aromaticum
In this investigation cold pressed clove (Syzygium aromaticum) oil (CO) was studied for its lipid classes, fatty acid profiles and tocol contents. The radical scavenging potential and antimicrobial properties of CO were also evaluated. The levels of neutral lipids in CO was the highest (ca. 94.7% of total lipids), followed by glycolipids and phospholipids. The main fatty acids in CO were linoleic and oleic, which comprise together ca. 80% of total fatty acids. Stearic and palmitic acids were the main saturated fatty acids. a- and γ-tocopherols and d-tocotrienol were the main tocols. CO quenched 70% of DPPH• radicals after 1 h, while extra virgin olive oil was able to quench only 45%. ESR measurements also showed the same pattern, wherein CO quenched 57% of galvinoxyl radical and olive oil deactivated about 38%. The results of antimicrobial properties revealed that CO inhibited the growth of all tested microorganisms. CO had a drastic effect on the biosynthesis of protein and lipids in the cells of B. subtilis. In consideration of is tpotential utilization, detailed knowledge on the composition and functional properties of CO is of major importance.Se ha estudiado el aceite de clavo (Syzygium aromaticum) obtenido mediante presión en frío (CO) y sus diferentes clases de lípidos, perfiles de ácidos grasos y contenido en tocoles. También se evaluó el potencial captador de radicales y las propiedades antimicrobianas del CO. Los niveles de lípidos neutros en CO fue mayoritario (aprox. 94,7% de lípidos totales), seguido de glicolípidos y fosfolípidos. Los principales ácidos grasos en CO fueron linoleico y oleico, que comprenden juntos el 80% de ácidos grasos totales. Los ácidos esteárico y palmítico fueron los principales ácidos grasos saturados. α- y γ-Tocoferol y δ-Tocotrienol fueron los principales tocoles. CO atrapó el 70% de los radicales DPPH• después de 1 h, mientras que el aceite de oliva virgen extra fue capaz de atrapar sólo el 45%. Las medidas de ESR también mostraron el mismo patrón, en el que CO inactivó 57% de radicales galvinoxil os y el aceite de olive desactivó aproximadamente el 38%. Los resultados de las propiedades antimicrobianas revelaron que el CO inhibió el crecimiento de todos los microorganismos ensayados. CO mostró un efecto drástico en la biosíntesis de proteínas y lípidos en las células de B. subtilis. En relación al potencial utilización, el conocimiento detallado de la composición y propiedades funcionales de CO es de gran importancia
Finite Element Modelling of Strengthened Simple Beams using FRP Techniques: A parametric Study
The main objective of this paper is to study analytically the strengthening of a simplereinforced concrete beams due to excessive uniform loads in flexure, shear and acombination of flexure and shear, using externally bonded FRP sheets technique. Acommercial finite element computer program ANSYS has been used to perform a structurallinear and non-linear analysis for several models using several schemes of FRP sheets. Aparametric study has been performed for a lot of strengthened beams. FE models studies amain parameter of different schemes of FRP sheets in flexure, shear and combinationflexure/shear. Comparing the results with a control beam model – simple reinforcedconcrete beam without strengthening – it is obvious that all strengthened beams have agreater ultimate capacity than the control beam and noticeable enhancement in memberductility. The increasing level differs as a result of the strengthening scheme. Thestrengthened beam in both flexure and shear gives a higher ultimate load capacity, delay thefailure and prevent debonding failure up to a level at which debonding occurs in bothlongitudinal and wrapped jackets CFRP sheets
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