Search results for " Chemical engineering"
showing 10 items of 2965 documents
A new copper(II) chelate complex with polyamines as fire retardant and epoxy hardener: Synthesis, crystal and electronic structure, and thermal behav…
2020
A new (ethylenediamine-N,N′)-(diethylenetriamine-N,N′,N″)-copper(II) hexafluoridosilicate complex, [Cu(eda)(deta)]SiF6 (1) (eda – ethylenediamine; deta – diethylenetriamine), was synthesized by direct interaction of anhydrous CuSiF6 with polyethylenepolyamine (pepa – H2N[C2H4NH]nH, where n = 1 (eda) and 2 (deta)). The crystals of 1 were characterized by IR spectroscopy and X-ray diffraction. Compound 1 consists of SiF62− discrete anions and [Cu(eda)(deta)]2+ complex cations whose Cu2+ ions are chelated by eda and deta. The coordination polyhedron of Cu(II) atom is an elongated square pyramid which consists of four nitrogen atoms belonging to NH2 groups of eda and NH2 and NH groups of …
Divided Wall Column Modeling and Simulation in an Open-Source Environment
2020
The divided wall column (DWC) can achieve sharp separations of three or more components in a single shell, substituting conventional sequences of two or more binary distillation columns, with lower expenses. Despite these advantages, DWC models are not available in commercial chemical process simulators. To simulate DWC, users must employ instances of conventional column model and couple them in different configurations. In this paper, a DWC model was developed in EMSO (Environment for Modeling, Simulation and Optimization). DWC model was then used for simulating the separation of an equimolar mixture of three hydrocarbons. Results show that, depending on the number of trays, DWC presented …
Innovación educativa para integrar la seguridad en asignaturas experimentales
2014
La formación es uno de los pilares esenciales para consolidar una auténtica cultura de la prevención que luego repercuta en el ámbito laboral. En Ingeniería Química, la formación en Higiene y Seguridad es absolutamente necesaria, por el tipo de equipos y productos manejados. Sin embargo, la integración de la prevención de riesgos en los nuevos planes de estudio de Ingeniería Química es muy variable, y todavía insuficiente para que los egresados estén capacitados para desarrollar su actividad profesional aplicando los principios de la prevención de riesgos. Aprovechando la puesta en marcha de los nuevos grados, se pensó desarrollar alguna estrategia para mejorar la formación en Seguridad de …
Metall-π-Komplexe von Benzolderivaten, XII Hyperfeinstruktur und Linienbreiten in den ESR-Spektren methylierter und deuterierter Bis(η-benzol)chrom(I…
1979
Die vollstandige Reihe der Methyl-Substitutionsprodukte des Bis(η-benzol)chrom(I)+·-Radikalkations sowie ausgewahlte deuterierte Derivate desselben wurden in Losung und in glasartig erstarrtem Medium ESR-spektroskopisch untersucht. 1H-, 2D- und 53Cr-Hyperfeinparameter werden mitgeteilt und das Proton/Deuteron-Kopplungskonstantenverhaltnis wird diskutiert. Die Betrage von a(1HAren) und a(1HMethyl) variieren innerhalb enger Grenzen (3,454,15 bzw. 0,50,7 G), wobei a(1HAren) mit zunehmendem Methylierungsgrad zunimmt. Um die Konformationsabhangigkeit von a(1HMethyl) zu studieren, werden die ESR-Spektren von (η12-[2.2]Paracyclophan)-chrom(I)+·, 21+·, und Bis(1,4-dimethyl-η6-benzol)chrom(I)+·, 5+·…
Valores personales y autoestima en población general y clínica
2008
The aim of this study is to investigate the association between personal values and self-esteem in general population and clinical population. The sample was composed of a group of patients with a diagnosis of anxiety disorders and/or depression (n = 60) and a comparison group, paired by sex and age, of general population (n = 60). The Portrait Values Questionnaire of Schwartz (PVQ) and the Autoe Self-esteem Scale were used. T-tests were performed to compare the scores of both instruments between the two groups. The clinical sample scored significantly lower in Self-esteem, Self- direction, Hedonism, and Openness to Change. For this reason, Pearson correlations were calculated in differenti…
La inteligencia de los niños
2005
Partial results of an investigation are presented whose primary objective is to adapt and to standardize the neurocognitive assessment battery C.A.S. of Das and Naglieri (1997) in a child sample. The test is an operationalization of a non traditional intelligence model (PASS) that considers the intelligent behaviors as a group of four cognitive basic processes (planning, attention, simultaneous and successive processing). The objectives of this work are to obtain the psychometric properties of the instrument and also, to analyze if differences exist according to sex and age. The study type is crosswise - transactional. It was administered the CAS to 150 children residents in Buenos Aires am…
Phosphotungstic acid (PTA) in the synthesis of 3D CdS superstructures by diffusion assisted hydrothermal method
2015
Abstract In this study, the synthesis of cadmium sulfide (CdS) microstructures by gas diffusion assisted hydrothermal method using phosphotungstic acid (PTA) is reported. The as-synthesized products were characterized by Fourier transform infrared (FTIR), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of PTA dose, thioacetamide amount, time and temperature on the morphology of obtained particles have been studied. In this process, PTA ion host stabilizes the CdS particles against aggregation and thioacetamide plays two roles, being at the same time a sulfur source and a capping ligand. Based on the performed analyses it seems that the thioacetamide is mor…
Caffeine analysis and extraction from a topical cream intended for UV-skin protection
2020
Made available in DSpace on 2021-06-25T10:16:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 This study aimed to develop and validate a method for the analysis of caffeine in complex cosmetic samples, such as sunscreens. Besides, an extraction method of caffeine from coffee oil and from creams, which contains both lipophilic and hydrophilic components, has been developed. The method to analyze caffeine was developed using an isocratic pump, Waters 1515 and an automatic injector Perkin-Elmer Series 200 and an UV detector Perkin-Elmer. As stationary phase, Kromasil C-18 (150 × 4.6 mm ID with particle size of 5 µm) column was used and a mixture of water (pH 4.00)/acetonitrile (…
Study of liquid–liquid equilibrium of the systems isobutyl acetate+acetic acid+water and isobutyl alcohol+acetic acid+water at different temperatures
2008
Abstract In this work, experimental liquid–liquid equilibria (LLE) data of the systems isobutyl acetate + acetic acid + water and isobutyl alcohol + acetic acid + water are presented. The liquid–liquid equilibria of both systems have been measured at 283.15 and 323.15 K. The NRTL and UNIQUAC models were applied to fit the data for both ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions. The experimental tie lines were compared to the values predicted by the UNIFAC method. Moreover, the solvent capabilities of isobutyl acetate and isobutyl alcohol were compared.
Progress in THz Rectifier Technology: Research and Perspectives
2022
Schottky diode (SD) has seen great improvements in the past few decades and, for many THz applications, it is the most useful device. However, the use and recycling of forms of energy such as solar energy and the infrared thermal radiation that the Earth continuously emits represent one of the most relevant and critical issues for this diode, which is unable to rectify signals above 5 THz. The goal is to develop highly efficient diodes capable of converting radiation from IR spectra to visible ones in direct current (DC). A set of performance criteria is investigated to select some of the most prominent materials required for developing innovative types of electrodes, but also a wide variet…