Search results for " Chemical Engineering"
showing 10 items of 2965 documents
Effect of operating conditions and feedstock composition on the properties of manganese oxide or quartz charcoal pellets for the use in ferroalloy in…
2020
peer-reviewed The full text of this article will not be available until the embargo expires on the 26/12/2021 This study investigates the effect of heat treatment temperature on the properties of charcoal composite pellets used for the reduction of ferroalloys. The heavy fraction of biooil was used as a binder for the charcoal ore pellet preparation. The effect of heat treatment temperature on the pellet shrinkage was related to the degree of reduction which varied with feedstock and ore composition. The results showed that the size and shape of the charcoal pellets were not affected by the biooil devolatilization. Manganese charcoal pellets showed higher electrical resistance during pyroly…
Pulsed electric fields as an alternative to thermal processing for preservation of nutritive and physicochemical properties of beverages: A review
2017
Fruit juices and other beverages constitute an important source of bioactive compounds, but thermal processing may reduce their contents thus decreasing natural nutritive value of foods. This has been recently led to the use of non-thermal technologies, especially pulsed electric fields (PEF) as an interesting alternative to thermal pasteurization of beverages. Reported results show that PEF is a useful for pasteurization of fruit juices that can minimize changes in physicochemical and nutritional properties with retention of higher amounts of health-related phytochemicals. This study presents an overview of the effect of PEF on the physicochemical (e.g., Brix, pH, viscosity, acidity, color…
Towards controlling PCDD/F production in a multi-fuel fired BFB boiler using two sulfur addition strategies. Part II: Thermodynamic analysis
2014
Abstract A staged equilibrium process model was developed for a bubbling fluidized bed boiler firing SRF, bark and sludge. The model was used to study the influence of sulfur addition strategies (S-pellet additive and peat co-firing) on the behavior of copper, bromine, and alkalis. Aerosol samples collected from the backpass of the boiler were used to validate the chemistry predicted by the model. The model revealed that Cu existed as Cu 2 S (s3) in the reducing zone, and CuCl (g) (for all test cases) and CuO (s) (during peat co-firing) in the oxidation zones. CuBr 3(g) was also present after the introduction of tertiary air. However the model failed to predict the formation of CuSO 4 , an …
Multiple-scan voltammetry and OCP: Archaeometric tools for dating archaeological bronzes
2021
[EN] The application of a multiple-scan strategy to nanosamples taken from 18 cross-sections of Bronze Age arms and armour, as well as two Roman coins using two solid-state electrochemical techniques, the voltammetry of immobilized microparticles (VIMP) and open circuit potential measurements (OCP) is described. The voltammetric responses in contact with aqueous acetate buffer can be attributed to the reduction of cuprite with variable degree of compaction and crystallinity revealing significant differences in the gradient of such properties with depth. Such differences are also revealed by "dry" OCP measurements connecting points in the cross section near and separated from the corrosion l…
A Solar Photothermocatalytic approach for the CO2 conversion: Investigation of different synergisms on CoO-CuO/Brookite TiO2-CeO2 catalysts
2022
Abstract The photoactive features of the least common polymorph of TiO2, i.e. brookite, were combined with the thermocatalytic redox ones of cerium oxide, focusing on the effects of the addition of small amounts of Co-Cu oxides for the solar CO2 conversion. By considering the characterization data, a surface segregation of the hosted metal oxides on the TiO2-CeO2 composite was evidenced, and their presence increased the amount of oxygen vacancies and improved the charge carriers separation. The bimetallic oxides-based sample was the most performing one in the photocatalytic carbon dioxide reduction at room temperature. The formation of carbon monoxide and methane was 5 and 0.5 μmol g−1h−1, …
Controlled radical polymerization of styrene in miniemulsion polymerization using reversible addition fragmentation chain transfer
2003
Abstract Miniemulsion polymerizations of styrene in the presence of two reversible addition–fragmentation chain-transfer (RAFT) agents were studied. The rates were significantly retarded by the presence of a RAFT agents S -(thiobenzoyl)thioglycolic acid, 1 , or dithiobenzoic acid 1-phenylethyl ester, 2 . Control in miniemulsion polymerization is not as good as for bulk polymerizations. The miniemulsions could also be stabilized against Ostwald ripening by a polymer terminated by a dithiobenzoic moiety. In this case, the polymerization was not controlled because of the generation of renucleated particles. To cite this article: I. Uzulina et al., C. R. Chimie 6 (2003).
Erysacleuxins C and D, new isoflavones from the twigs of Erythrina sacleuxii Hua and their cytotoxic activity
2020
Two previously undescribed isoflavones, erysacleuxin C (1) and erysacleuxin D (2), together with seven known compounds (3–9), were isolated and identified from the EtOAc extract of the twigs of Erythrina sacleuxii Hua (Leguminosae). The structures of the isolated compounds were determined on the basis of their spectroscopic and spectrometric data. Evaluation of their cytotoxicity against the human cancer HeLa-S3 cell lines indicated IC50 values of 130.4, 54.9 and 73.9 µM for erysacleuxin C (1), erysacleuxin D (2) and butin (9), respectively. Keywords: Erythrina sacleuxii, Leguminosae, Isoflavone, Erysacleuxin C, Erysacleuxin D, Cytotoxicity
Organizational Virtues, Performance and Job Satisfaction. Differences according individual and organizational factors in Argentinean employees
2017
El presente trabajo se basa en las propuestas de la Psicología Organizacional Positiva (POP) que intenta integrar a la mirada clásica de estudios organizacionales –que se focaliza en analizar condiciones negativas–, una perspectiva que visualice variables positivas que contribuyan a obtener resultados óptimos (Cameron & Spreitzer, 2012). Se planteó como objetivo analizar si existen diferencias en las virtudes nivel organizacional (Apoyo y respeto, Significado e inspiración, Perdón) según variables individuales (e.g. personal a cargo) y organizacionales (e.g. tamaño y tipo de empresa). Asimismo, se buscó establecer si existe relación entre dichas virtudes y medidas resultado (performance org…
Preliminar construction of a multidimensional scale to assess clinical symptoms of anxiety. Evidences of content and face validity
2017
La medición de la ansiedad debería contemplar la multidimensionalidad de este constructo. Los instrumentos de uso local presentan limitaciones relacionadas con su abordaje incompleto, el contenido de sus ítems, la capacidad para discriminar los síntomas ansiosos de los depresivos y la desactualización con respecto a los diagnósticos vigentes. Un instrumento que tome en cuenta la conceptualización multidimensional de ansiedad y los criterios diagnósticos para el trastorno de ansiedad según la última versión del Manual de Diagnóstico y Estadístico de los Trastornos Mentales (DSM-5; American Psychiatric Association, 2013) podría responder a las limitaciones de sus predecesores. L…
High Five Model: The High Factors are Associated with Low-Risk of Medical, Mental and Personality Diseases
2017
El Modelo de los Cinco Altos (MCA; High Five Model, HFM, por sus siglas en inglés)establece cinco rasgos positivos de la personalidad: erudición, paz, jovialidad, honestidad,y tenacidad, llamados factores altos. Un estudio previo había mostrado la validezconvergente, discriminante y estructural del MCA. Este estudio tuvo por objetivocorroborar que el MCA está asociado positivamente a variables relacionadas con la saludfísica y mental de los individuos. Se realizó este estudio con una muestra de participantesde población general no consultante. Específicamente, se estudió la asociación entre losfactores del MCA y el modelo de Salud Mental Positiva, el bajo riesgo de enfermedadmédica, la ause…