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The photoelectrocatalytic oxidation of an anionic surfactant (internal olefin sulfonate C20-C24, IOS) in synthetic oilfield wastewater was investigated by photocurrent measurements using a sulfur and nitrogen co-doped titanium dioxide electrode (S,N-TiO2/Ti). For the electrode preparation, S,N-TiO2 films were supported on Ti expanded meshes by sol–gel dip-coating, followed by thermal treatment at 400 °C. Photocurrent measurements were performed by linear sweep voltammetry (LSV) under UV–Vis irradiation using different IOS concentrations (20–200 ppm). The photocurrent values obtained at 0.5 V vs Ag/AgCl (iph) for each IOS concentration (CIOS) were used to plot the 1/iph vs 1/CIOS graph, in which two trends were identified. For high IOS concentrations (70–200 ppm), the values fitted well to the unimolecular Langmuir–Hinshelwood (LH1) kinetic model (R2 = 0.973), which can be associated with the direct oxidation mechanism. For low IOS concentrations (20–70 ppm), the values fitted better to a linear combination of both unimolecular and bimolecular Langmuir–Hinshelwood (LH1 and LH2) kinetic models (R2 = 0.854), which can be associated with direct and indirect oxidation mechanisms, respectively. These results suggest that at high IOS concentrations the IOS adsorption plays the main role on the photoelectrocatalytic oxidation, while at low IOS concentrations both IOS adsorption and H2O adsorption (surface hydrophilicity) play important roles on the photoelectrocatalytic oxidation.

Ilmenite (FeTiO3) concentrates were modified by high energy ball milling (HEBM) at different times (1, 2, and 3 h) and in the presence of MgO or metallic Mg at different contents (0.5, 1.0, and 3.0 wt%), with the aim of obtaining a low-cost and highly available photocatalyst with enhanced performance towards H2 production. FeTiO3 concentrates were obtained from ilmenite-rich black sand by gravimetric concentration followed by wet electromagnetic and dry magnetic separation. HEBM was performed to insert Mg into FeTiO3 structure and to simultaneously reduce the particle size. The insertion of Mg intended to shift the conduction band of the materials to more negative potentials, in spite of the band-gap widening. XRD patterns of the milled samples showed a decrease in the intensity of ilmenite peaks without any displacement, indicating slight amorphization without significant changes in the crystalline structure. However, the increase in the intensity of hematite peaks suggests substitutional doping according to the proposed solid-state reactions. Although thermodynamic analyses showed that doping with metallic Mg should be more favorable, doping with MgO appears to be kinetically favored due to the physical characteristics of the precursor, as it was revealed by XRD, XPS, Raman spectroscopy, SEM–EDS, and UV–Vis DRS results. Deconvolution of high-resolution XPS spectra corresponding to Mg1s exhibited the presence of an additional component peak for the sample milled with metallic Mg, in comparison to that with MgO. This result evidenced the formation of a new phase, suggesting that part of the metallic Mg was not inserted into FeTiO3, as it was confirmed by Raman spectroscopy. UV–Vis DRS analyses showed an increase in the band-gap of the samples milled in the presence of Mg precursors (from 2.51 to 2.55–2.59 eV) which were attributed to slight modifications of the conduction band due to the insertion of Mg. The performance towards hydrogen production under UV irradiation was improved from 240.5 µmol g−1 h−1 (unmilled sample) to 255.3 µmol g−1 h−1 (2 h milled in the absence of Mg precursor), 296.0 µmol g−1 h−1 (2 h milled with 1.0 wt% MgO), and 265.2 µmol g−1 h−1 (2 h milled with 1.0 wt% metallic Mg). This improvement was attributed mainly to the insertion of Mg, and the consequent modification of the band structure, rather than the modification in the surface area.

La MidBo se ha consolidado como un lugar necesario para escudriñar lo real. A su vez, en enlace con Alados, fortalece a una comunidad de creadores-espectadores que consolida la práctica documental en Colombia, expande sus fronteras y, ante todo, construye un espacio-público que no solo nos invita a ver documentales, sino a hilar y a compartir reflexiones sobre sus modos de producción e interpretación. Territorio y memoria sin fronteras es una memoria selectiva de la primera etapa del Seminario Pensar lo Real (2015-2018) que tuvo cinco ejes: cartografías del documental iberoamericano, diálogos documentales, políticas del documental, claves de creación y nuevas etnografías. Ben Russell, María Luisa Ortega, Jorge La Ferla y María Fernanda Arias son algunos de los autores, cuyas voces se encuentran en esta nueva edición de Cuadernos de Alados para Pensar lo Real.

espanolEn este articulo de investigacion se amplia el concepto de cromatismo dentro de los corales de J. S. Bach, concepto y materiales que son tradicionalmente incluidos en los programas de formacion musical a nivel de pregrado. Asi, del analisis de los corales surge la discusion que lleva a cuestionar si la clasificacion actual de los cromatismos es la que mejor explica cada uno de los eventos cromaticos que ocurren en este repertorio, planteando la tesis de que los cromatismos no estructurales (cne) en realidad no existen en estos corales, sino que cumplen una funcion tonal (cft) que busca establecer, melodica o armonicamente, una nueva estructura diatonica o centro tonal. Asi mismo, esta investigacion analiza y explica seis casos excepcionales unicos que sirven para corroborar la teoria que se propone al poder agruparse dentro de algunas de las categorias propuestas. EnglishThis research broadens the concept of chromaticism in J. S. Bach’s chorales; concept and materials that are currently included in music training programs at the undergraduate level. Thus, the idea that the Nonessential Chromaticism (NC), which is explained by the traditional theory, virtually doesn’t exist in this music. On the contrary, all of these chromatic events have a Tonal Function (CTF) that is not explicit at the moment of their appearance, but it is part of a new chord or a melodic movement that belongs to a new scale or a new tonality. Likewise, this research attempts to explain the only six exceptional cases that serve to corroborate this theory because they can be grouped into some of the categories. portuguesEsta pesquisa expande o conceito de cromatismo dentro dos corais de J. S. Bach; conceito e materiais que sao tradicionalmente incluidos em programas de treinamento de musica no nivel de graduacao. Assim, a partir da analise dos corais surge a discussao que leva a questionar se a classificacao atual dos cromatismos e a que melhor explica cada um dos eventos cromaticos que ocorrem nesse repertorio, levantando a tese de que os Cromatismos Nao Estruturais (CNE) na realidade, eles nao existem nesses corais, mas eles preenchem uma Funcao Tonal (CFT) que procura estabelecer, melodicamente e / ou harmonicamente, uma nova estrutura diatonica ou centro tonal. Da mesma forma, esta pesquisa analisa e explica seis casos excepcionais unicos que servem para corroborar a teoria que se propoe a ser agrupada em algumas das categorias propostas.

Ilmenite-rich black sands from an alluvial deposit of Barbacoas (Narino, Colombia) were used as a natural source aiming to obtain a low-cost and highly available photocatalyst. Mineral concentrates were obtained by gravimetric concentration in a Wilfley table (deck tilt angle: 11–14°) followed by dry magnetic or wet electromagnetic separation. Afterwards, the particle size was manually reduced down to −325 mesh. Rietveld refinements using X-ray diffraction data showed that the highest purity achieved was 93.46% of ilmenite (FeTiO3). Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy revealed a polyhedral morphology with an average grain size of 1.33–2.27 μm, granular inclusions of aluminosilicates and appreciable quantities of manganese. The band-gap values determined by UV-Vis diffuse reflectance spectroscopy were underestimated compared to those reported in the literature, given the impurities in the samples and their optical behavior. Photoluminescence experiments provided a band-gap of 2.68 eV. The photo-oxidative and photo-reductive capabilities of the concentrates were evaluated in the degradation of methyl orange in aqueous solution under UV irradiation. 99% of discoloration was achieved after 50 min for oxidation and after 20 min for reduction, showing the potential of ilmenite-rich concentrates as photocatalysts.

The simultaneous hydrogen production and oxidation of phenol by photoelectrolysis using mixed oxide semiconductor films of Bi–Nb–M–O (M = Al, Fe, Ga, In) was evaluated in a three-electrode cell. The experiments were carried out under visible light irradiation. The films were prepared on AISI/SAE 304 stainless steel plates by the sol–gel method and deposited using the dip-coating technique. The films have been previously characterized by SEM-EDS, XRD and XPS. XPS deconvolution spectra reveal that the Nb is present as a dopant in all the films. Linear sweep voltammetry and current–time measurements show that all the films exhibit higher electron transport properties under visible light in comparison with the analogous electrolytic process (in the dark). All the films have the ability to carry out simultaneously the hydrogen production and the oxidation of phenol in the reaction conditions evaluated. The Bi–Nb–Fe–O/304 SS film exhibits the highest photoelectrolytic activity related to its lower band-gap and the presence of BiFeO3 perovskite-type phase. The results indicate that these materials can be used in photoelectrolytic cell for simultaneously environmental remediation processes and hydrogen production.

El artículo realiza un recorrido por los orígenes del debate sobre lademocracia participativa y sus variantes, algunos desarrollos recientes,críticas que han surgido frente a las propuestas conceptuales, y prácticaspara llevarla a cabo en diferentes contextos. Esto con el fin de presentarun marco analítico y conceptual que supere la preeminencia a diseñarmodelos para aplicar a diversos contextos institucionales de antemanopara validar su ajuste o no a unas variables. Enfatizaremos en la variante radical de la democracia sin desconocer que en la actualidad fácticamente, no se ha logrado extender la participación a espacios que superen lo local, que a su vez no sean fácilmente cooptados por lógicas elitistas, representativas y excluyentes. Las cuales se constituyen en alternativas limitadas para hacer de la democracia una forma de construcción de relaciones sociales que conduzcan a la emancipación social junto a la construcción de un ethos político agonista, que posibilite repensar la democracia más allá de arreglos institucionales universalizantes, desconocedores de la diversidad presente en distintos contextos.

Rev.esc.adm.negSi bien muchas de las problemáticas ambientales actuales tienen un alcance global, sus impactos se experimentan a nivel local con repercusiones en los territorios, la población y la economía. Por tanto, las medidas para mitigar dichas problemáticas deben originarse en iniciativas locales que respondan de manera precisa a las necesidades identificadas por los actores sociales, a la vez que se haga uso de los recursos y las capacidades disponibles en el territorio.Si en algo existe consenso, es en que hacer frente a los problemas ambientales actuales, demanda un cambio en los sistemas de producción y consumo, hacia prácticas que garanticen un uso más eficiente y sostenible de los recursos, en donde un cambio en el patrón energético juega un papel fundamental, debido al impacto que ha generado el uso de los combustibles fósiles. Frente a este desafío se requiere de la capacidad emprendedora e innovadora de los agentes, de manera que sea posible incorporar al sistema nuevos métodos de producción, nuevos insumos y productos, y nuevas formas de hacer las cosas.Es en este sentido que las energías renovables cobran un papel importante dado que surgen como una alternativa para enfrentar el agotamiento de los combustibles fósiles y a su vez, como una forma de reducir las externalidades negativas asociadas al consumo de energía. Por tanto el objetivo del presente artículo, es presentar una revisión teórica respecto al papel que juega el emprendimiento en el desarrollo y fortalecimiento de las capacidades endógenas para el aprovechamiento local de las fuentes renovables de energía.

El presente articulo estudia las medidas cautelares como mecanismo de proteccion al derecho a un medio ambiente sano estipulado en los articulos 79 y 80 de la Constitucion Politica de Colombia de 1991. Concretamente se refiere a la defensa de los recursos hidricos a traves de la accion popular (art. 88 C.P.), reglamentada en la ley 472 de 1998 como un mecanismo de proteccion de los derechos e intereses colectivos y difusos relacionados con el ambiente sano. Ademas se determina la importancia de las medidas cautelares para la proteccion del recurso hidrico mediante la interpretacion y aplicacion que realicen los jueces en las acciones populares, bajo el principio de prevencion, segun el cual la decision de los jueces debe garantizar los derechos transgeneracionales a un medio ambiente sano de las generaciones futuras. Tambien se compilan las normas colombianas sobre proteccion de los recursos hidricos, especificamente las correspondientes al ecosistema de paramos, donde nacen las cuencas hidrograficas del pais, que son objeto de estudio por la importancia para las diferentes disciplinas por su impacto social. Se concluye con un estudio sobre la importancia de la salvaguarda constitucional y proteccion de los derechos transgeneracionales por medio de medidas previas aplicadas transitoriamente cuando se pueda causar un dano inminente durante la accion legal.

Loading a cocatalyst onto a photoelectrodes is a wide spread strategy to enhance the efficiency of the photoelectrochemical water splitting process [(Yang, Wang, Han, & Li, 2012)]; however, its performance is strongly dependent of the method employed to form the heterojunction between cocatalyst and photoelectrode, as well as the alignment of their energetic levels to separate successfully the photogenerated charge carriers. In this study, we report water splitting photoanodes constituted from TiO2 nanotubes arrays decorated with coordination polymers as cocatalyst. Highly ordered TiO2 nanotubes were synthesized by the electrochemical anodization process of titanium (Ti) foil in a 0.2 M NH4F, ethylene glycol/10% H2O electrolyte under constant anodization time and applied potential. Coordination polymers were deposited onto TiO2 nanotubes by using the low cost successive layer adsorption and reaction (SILAR) method. Cocatalyst was successfully deposited on TiO2 nanotubes with tunable loading amounts by controlling the deposition cycles of SILAR. The structural characterization, morphology, elemental composition and light absorption capability of the samples were characterized by XRD, RAMAN, FT-IR, FE-SEM, EDX and UV–Vis methods respectively. Furthermore, the semiconducting properties of the modified TiO2 nanotubes were also estimated from Mott-Schottky plots. It was found that under illumination, the cocatalyst can efficiently collect photogenerated holes from the TiO2 nanotubes electrodes promoting charge separation and lowering the onset potential which yields an increased water oxidation efficiency. Yang, J., Wang, D., Han, H., & Li, C. (2012). Roles of Cocatalysts in Photocatalysis and Photoelectrocatalysis. Accounts of Chemical Research, 46(8), 1900–1909. https://doi.org/10.1021/ar300227e

Photoelectrochemical (PEC) water splitting using semiconductor electrodes has received much attention in the last decades. In this sense, hematite photoanode has appeared as a good candidate due to it is synthetized from cheap and abundant elements, non-toxicity and has a band gap of 2.1 eV that permits the absorption of visible light (Sivula, Le Formal, & Grätzel, 2011). However, their transport properties change drastically depending of synthesis method employed and the different morphologies obtained (Horiz et al., 2016). In this study, we report the electrochemical growth of hematite (α-Fe2O3) nanostructures by anodization process of carbon steel substrates in an ethylene glycol based medium. The influence of experimental parameters including the NH4F concentration, anodization time and applied voltage were systematically investigated to study their electrochemical properties. The obtained films were heat treated to 500 ºC to obtain the hematite crystalline phase. The crystalline phase was determined using an X-ray diffraction and Raman spectroscopy. FE-SEM images of the hematite nanostructures films provided morphological parameters. Photoelectrochemical characterization was achieved through OCP, LSV, CA and EIS procedures. A hard dependence between the synthesis variables and their photoelectrochemical properties for water splitting reaction was observed. Horiz, N., Tamirat, A. G., Rick, J., Dubale, A. A., Su, W.-N., & Hwang, B.-J. (2016). Using hematite for photoelectrochemical water splitting: a review of current progress and challenges. Nanoscale Horizons, 1, 243–267. https://doi.org/10.1039/c5nh00098j Sivula, K., Le Formal, F., & Grätzel, M. (2011). Solar water splitting: Progress using hematite (α-Fe2O3) photoelectrodes. ChemSusChem, 4(4), 432–449. https://doi.org/10.1002/cssc.201000416

TiO2 films obtained by sol-gel method and dip-coating technique is a methodology flexible, economical and reproducible. It has been used in applications such as: photocatalysis, photoelectrochemical, hydrogen production, solar cells and many others. Particularly, for the photoelectrochemical water oxidation has received great attention, since this is the semi-reaction that occurs at the photoanode (TiO2 film) during the production of hydrogen from water [1]. However, to ensure the good performance of these materials it is necessary to know their semiconductor properties. In this work, the visible light activity and photoelectrochemical properties of N,S-TiO2 films supported on metal meshes were evaluated for the water oxidation. The N,S-TiO2 films were prepared by sol–gel dip-coating on titanium grade 2 expanded mesh. The procedure was adapted from that described elsewhere [5]. Titanium (IV) butoxide was used as N,S-TiO2 precursor and thiourea was used as nitrogen and sulfur dopant precursor. The volume ratio alkoxide : alcohol (solvent) was 1.0 : 4.6, the molar ratio alkoxide : acetylacetone (complexing agent) was 1.0 : 1.5 and the molar ratio alkoxide : water was 1.0:2.8 [2]. Morphology, crystalline phase and optical band gap energy were determined by FE-SEM with energy-dispersive X-ray spectroscopy (EDS), XRD, and diffuse reflectance UV-visible spectroscopy (DRS). Open circuit potential (OCP) measurements were conducted in the dark and under Vis illumination in order to evaluate the photocatalytic activity of the TiO2 film. The illumination was provided externally by a Xe lamp (Newport 66984-300XV-R1). The semiconducting properties of the films were obtained by open circuit potential (OCP), linear sweep voltammetry (LSV), Electrochemical Impedance Spectroscopy (EIS-OCP), Cyclic voltammetry (CV), Linear sweep voltamperometry (LSV-On/Off), Chronoamperometry (CA) with chopped light and the Mott-Schottky analysis. The (photo)electrochemical tests were carried out in a conventional three-electrode cell equipped with a borosilicate window to allow the UV light illumination of the entire portion (1 cm2) of theTiO2 film exposed to the electrolyte. An Ag/AgCl (3M KCl) electrode was employed as reference electrode and a graphite bar (99.999% Alfa Aesar) as counter electrode. The 0.1 M KClO4 aqueous electrolyte. Before each test, the electrolyte was bubbled with N2 gas during 20 min. The illumination was provided externally by a Xe lamp (Newport 66984-300XV-R1). Changes in the OCP a semiconductor film of N,S TiO2 supported on a mesh of titanium under intermittent illumination are shown in Fig. 1. In Fig. 1, it can be seen that when the light is on and the photoanode illuminate a displacement occurs in the potential to negative values, associated with the generation of charge carriers in the semiconductor in the presence of light (foto-huecos and photogenerated electrons) [3]. Under ilumination a potential variation towards more negative values is observed until a photostationary steady state is reached. When the illumination is interrupted, the OCP recovers its value in the dark. The linear sweep voltammogram for N,S-TiO2 in the dark and illumination is shown in Fig. 2 In Fig. 2 it can be see that under illumination an increase in the current occurs when the potential swep starts. It is due to the applied potential creates an electric field inside it that favors the separation of the photogenerated e - h + pairs The chronoamperometry with chopped light for N,S TiO2 films is shown in Fig. 3. In Fig. 3, It can see that N-S TiO2 films showed a constant photogenerated currents and also good stability as the illumination period was repeated. However, TiO2 films the showed a decrease in photogenerated currents. References [1] P. Acevedo-Peña, I. González, J. Electrochem. Soc. 160 (2013) 452 [2] M.I. Jaramillo-Gutiérrez, E.P. Rivero, M.R. Cruz-Díaz, M.E. Niño-Gómez, J.A. Pedraza-Avella, Catal. Today. 266 (2016) 17. [3] D. Ramirez-Ortega, A.M. Meléndez, P.Acevedo-Peña, I. González, R. Arroyo, Electrochim. Acta, 140 (2014) 541. Figure 1

We have cloned and characterized a cDNA clone, called Fapmsr, coding for a putative peptide methionine sulphoxide [Met(O)] reductase (PMSR, EC 1.8.4.6) from strawberry fruits (Fragaria x ananassa). This gene is involved in the repair of inactive peptides and proteins caused for the oxidation of methionine residues to Met(O). Expression of the Fapmsr was only detected in the receptacles of red mature fruits and not in young or immature fruits nor in other plant tissues such as flowers, leaves, runners, roots or achenes. Expression of the Fapmsr gene was activated in green immature fruits when achenes were removed from receptacles, and this was prevented by the application of exogenous auxins such as naphthaleneacetic acid. The enzyme produced and purified by cloning the strawberry cDNA in frame with the C-terminal sequence of the glutathione S-transferase gene can reduce free Met(O) to methionine as analysed by reverse phase high performance liquid chromatography. We have also set up a PMSR protection assay that demonstrates that this enzyme can protect in vivo against the damage produced by the addition of H2O2.

Phenol (C6H5OH) is an organic compound which is widely used in the industrial production of plastics, paints, rubber, paper, and soaps; However, due to its characteristics of toxicity and persistence in the environment is registered in the list of hazardous substances of the Environmental Protection Agency (EPA) [1,3]. One of the main effluents in which phenol is found are industrial wastewater by which the permissible limits established by the competent environmental authorities are reached, which causes serious problems in the health of people living in places nearby the points of water dump. There are several techniques and methods for determining phenol concentration in water. Conventional techniques include visible ultraviolet spectrophotometry (UV-VIS), High Performance Liquid Chromatography (HPLC), and Gas Chromatography coupled with Mass Spectrometry (GC-MS). These techniques, although characterized by their precision, require a sample pretreatment, high cost equipment and consumed long analysis times [1,3], which makes it difficult to obtain results in real time that allow the control in the concentration of phenol in water before of being poured. One of the systems that has gained importance for measuring organic compounds in water and in real time is the Quartz Crystal Microbalance (QCM). This technique comprises a thin quartz crystal sandwiched between two metal electrodes and senses the changes in frequency that suffers the quartz crystal when a certain amount of mass is deposited on its surface [1,3]. In order to improve the sensitivity of the QCM, there have been used coatings on quartz crystal electrode surface, for example for phenols determination polymethylmethacrylate (PMMA) is used. The main objective of this research is to determine in real time and in continuous flow the concentration of phenol in water using the technique QCM with PMMA as coating on quartz crystal electrode surface. This work is conducted in two stages mainly:1. Determination of a suitable layer of PMMA to use as coating on quartz crystal electrode surface, and 2. Determination of the concentration of phenol using the coating of PMMA prepared in the stage 1. Results have shown that the PMMA films are more uniform when is used dichloroethane as solvent instead of chloroform, and the stability and sensitivity in the measurements are improved due to its vapor pressure that allows more dispersion of the polymer during spin coating, which is consistent with other authors [2]. The coating of 0.2% w/v of PMMA/dicloroethane allowed the shortest response time with adequate sensitivity. Finally, increase in the concentration of phenol increases the changes in frequency of the quartz crystal in a linear way as shown in Figure 1, which is consistent with other authors [1]. Figure 1. Change of frequency changing concentration of phenol Keywords : Quartz crystal microbalance, PMMA, phenol, water, real time. Mirmosheni, A., Oladegaragoze, A. Application of the quartz crystal microbalance for determination of phenol in solution. 2003. Sensors and Actuators, B: Chemical, Vol.98 (1), p. 28-36. Mohajerani, E. Morphological and thickness analysis for PMMA spin coated films. 2007. Journal of optoelectronics and advanced materials, Vol. 9 (12), p. 3901-3906. Reddy, S. Detection of phenol in aqueous solution using an AT-cut quartz thickness shear mode sensor. 2000. Materials Science and Engineering C, Vol. 12 (1), p. 23-28. Figure 1

Phenols (phenol, m-cresol, o-cresol and p-cresol) are contaminant compounds and due to its toxicity and persistence in the environment are listed in the Environmental Protection Agency as dangerous substances [1]; its presence in the environment is widely associated with wastewater effluents as is the produced water generated by oil and gas production. One of the systems that has been gaining importance to measure phenols in real time is the Quartz Crystal Microbalance (QCM). This technique comprises a thin quartz crystal sandwiched between two metal electrodes and senses the changes in frequency that suffers the quartz crystal when a certain amount of mass is deposited on its surface [3]. In order to improve the sensibility of compounds to measurement using a QCM have been used coatings on quartz crystal electrode surface, for example for phenols determination polymethylmethacrylate (PMMA) is used. The main objective of this research is to determine in real time and in continuous flow the concentration of phenolic compounds in produced water using the technique QCM with PMMA as coating on quartz crystal electrode surface. This work is conducted in three stages mainly: 1. Determination of a suitable layer of PMMA to use as coating, 2. Evaluation of the effect of the concentration of phenols, pH and flow rate in the measurements by QCM, 3. Comparison of sensitivity and time response obtained in the technique QCM with standard method by colorimetry. Results have shown that the PMMA films are more uniform when is used dichloroethane as solvent instead of chloroform and the stability and sensitivity in the measurements improve due to the vapor pressure of solvent that allows more dispersion of the polymer during spin coating, which is consistent with other authors [2]. Increase in the concentration of phenolic compounds, the flow rate and the pH increases the changes in frequency of the quartz crystal. Keywords : Quartz crystal microbalance, PMMA, phenols, produced water, real time. Mirmosheni, A., Oladegaragoze, A. Application of the quartz crystal microbalance for determination of phenol in solution. 2003. Sensors and Actuators, B: Chemical, Vol.98 (1), p. 28-36. Mohajerani, E. Morphological and thickness analysis for PMMA spin coated films. 2007. Journal of optoelectronics and advanced materials, Vol. 9 (12), p. 3901-3906. Reddy, S. Detection of phenol in aqueous solution using an AT-cut quartz thickness shear mode sensor. 2000. Materials Science and Engineering C, Vol. 12 (1), p. 23-28.

A derivative of D-xylose, 1,2-O-isopropylidene-α-D-xylofuranose (1), with Ti(OiPr)4 was used as a chiral catalyst in the asymmetric alkylation of benzaldehyde with diethylzinc (Et2Zn) for the high-yield production (90% conversion) and moderate enantioselectivity (45% ee (S)) of 1-phenyl-1-propanol. Optimum conditions (conversion and enantioselectivity) for the catalytic system formed by 1 and Ti(IV) were 10.0 mol % of 1 and 1 equivalent of Ti(IV) with respect to benzaldehyde in CH2Cl2 as a solvent, at room temperature. In the asymmetric alkylation of benzaldehyde with Et2Zn compound 1 in substoichiometric amount with Ti(OiPr)4 forms a chiral catalyst of the Ti(IV)-sugar type that ensures the good-yield conversion and the enantioselectivity of the reaction. Um derivado da D-xylose, 1,2-O-isopropilideno-α-D-xilofuranose (1), com Ti(OiPr)4 foi usado como catalisador chiral na alquilação assimétrica do benzaldeído com dietilzinco (Et2Zn) para produção de 1-fenil-1-propanol em alto rendimento (conversão de 90%) e enantiosseletividade moderada (45% ee (S)). As condições ótimas (conversão e enantiosseletividade) para o sistema catalítico formado por 1 e Ti(IV) foram 10.0 mol % de 1 e 1 equivalente de Ti(IV) com relação ao benzaldeído em CH2Cl2 como solvente, a temperatura ambiente. Na alquilação assimétrica do benzaldeído com Et2Zn, o composto 1 em quantidade sub-estequiométrica com Ti(OiPr)4 forma um catalisador quiral do tipo Ti(IV)-açúcar, o que assegura uma conversão com bom rendimento e a enantiosseletividade da reação.