Embrapa Instrumentation

São Carlos, Brazil

Embrapa Instrumentation

São Carlos, Brazil

Time filter

Source Type

Castro I.A.,Federal University of São Carlos | Byzynski G.,São Paulo State University | Dawson M.,Federal University of São Carlos | Ribeiro C.,Embrapa Instrumentation
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2017

The present study shows how electronic parameters (e.g. band gap energy, band edge positions) on semiconductors affect photoelectrochemical activity in simulated solar light using WO3, TiO2 and WO3/TiO2 as model systems. Hydrothermal synthesis was conducted to study heterostructure (HE) formation, which the loading of WO3 in TiO2 structure were varied to 20, 40 and 80 wt%. Scanning electron microscopy images show that WO3 and TiO2 particles are in contact with each other and the synthesis method as well as the deposition method are appropriate for the formation of WO3/TiO2 HE film. Important findings were obtained with a hole scavenger during photoelectrochemical characterization of WO3/TiO2–40 wt% film. This strategy was effective to clearly distinguish charge transport from charge separation, the essential mechanisms that affect water splitting which are often misinterpreted experimentally for HE. The hole scavenger experiment depicts the increase by 17.5% in photocurrent density for the WO3/TiO2–40 wt% film as compared to WO3 film, corresponding to 210 and 12 μA cm−2 vs Ag/AgCl respectively. Additionally, this HE film showed water oxidation initiated at lower applied potentials and indicating that coupling of the materials resulted in optimization of band edge properties for water splitting with the increase on light absorption at the visible range. Flat band potential was determined by the Mott-Schottky plot and it indicated the difference of 1.08 V vs Ag/AgCl between TiO2 and WO3 potentials, which makes the charge injection from one structure to another effective and thermodynamically stable for charge separation. A charge carrier density of 1.59 × 1020 was observed for the WO3/TiO2–40 wt% and it supports the best photoelectrochemical performance for water oxidation. © 2017 Elsevier B.V.

Pinto A.S.S.,Federal University of São Carlos | Pereira S.C.,Embrapa Instrumentation | Ribeiro M.P.A.,Federal University of São Carlos | Farinas C.S.,Federal University of São Carlos
Bioresource Technology | Year: 2016

Rapid, efficient, and low-cost technologies for monitoring the fermentation process during second generation (2G) or cellulosic ethanol production are essential for the successful implementation of this process at the commercial scale. Here, the use of near-infrared (NIR) spectroscopy associated with partial least squares (PLS) regression was investigated as a tool for monitoring the production of 2G ethanol from lignocellulosic sugarcane residues including bagasse, straw, and tops. The spectral data was based on a set of 103 alcoholic fermentation samples. Models based on different pre-processing techniques were evaluated. The best root mean square error of prediction (RMSEP) values obtained in the external validation were around 3.02. g/L for ethanol and 6.60. g/L for glucose. The findings showed that the PLS-NIR methodology was efficient in accurately predicting the glucose and ethanol concentrations during the production of 2G ethanol, demonstrating potential for use in monitoring and control of large-scale industrial processes. © 2015 Elsevier Ltd.

Cunha F.M.,Federal University of São Carlos | Esperanca M.N.,Federal University of São Carlos | Zangirolami T.C.,Federal University of São Carlos | Badino A.C.,Federal University of São Carlos | Farinas C.S.,Embrapa Instrumentation
Bioresource Technology | Year: 2012

Sequential solid-state and submerged cultivation with sugarcane bagasse as substrate for cellulase production by . Aspergillus niger A12 was assessed by measuring endoglucanase activity. An unconventional pre-culture with an initial fungal growth phase under solid-state cultivation was followed by a transition to submerged fermentation by adding the liquid culture medium to the mycelium grown on solid substrate. For comparison, control experiments were conducted using conventional submerged cultivation. The cultures were carried out in shake flasks and in a 5-L bubble column bioreactor. An endoglucanase productivity of 57. ±. 13. IU/L/h was achieved in bubble column cultivations prepared using the new method, representing an approximately 3-fold improvement compared to conventional submerged fermentation. Therefore, the methodology proposed here of a sequential fermentation process offers a promising alternative for cellulase production. © 2012 Elsevier Ltd.

De Mendonca V.R.,Federal University of São Carlos | Mourao H.A.J.L.,Federal University of São Carlos | Malagutti A.R.,Federal University of Vales do Jequitinhonha and Mucuri | Ribeiro C.,Embrapa Instrumentation
Photochemistry and Photobiology | Year: 2014

Despite photocatalytic degradation is studied generally focusing the catalyst, its interaction with the contaminant molecule plays a fundamental role in the efficiency of that process. Then, we proposed a comparative study about the photodegradation of two well-known dyes, with different acidity/basicity - Methylene Blue (MB) and Rhodamine B (RhB), catalyzed by TiO2 nanoparticles, varying both dye and photocatalyst concentrations. The results showed that the amphoteric character of MB molecules, even in a range of concentration of 5.0-10.0 mg L-1, did not imply in pH variation in solution. Therefore, it did not affect the colloidal behavior of TiO2 nanoparticles, independent of the relative dye/catalyst concentration. The acid-base character of RhB influenced the resultant pH of the solution, implicating in different colloidal behavior of the nanoparticles and consequently, in different degradation conditions according to dye concentration. As the isoelectric point of TiO2 is between the pH range of the RhB solutions used in this study, from 1.0 to 7.5 mg L -1, the resultant pH was the key factor for degradation conditions, from a well dispersed to an agglomerated suspension. Plot presenting the relation between photoinduced RhB photodegradation rate constant (k* = k'/[TiO2]) as a function of TiO2 photocatalyst and Rhodamine B initial concentration. © 2013 The American Society of Photobiology.

Farinas C.S.,Embrapa Instrumentation | Farinas C.S.,Federal University of São Carlos
Renewable and Sustainable Energy Reviews | Year: 2015

Solid-state fermentation (SSF) processes have enormous potential for many new applications using the bioconversion of agro-industrial residues into biofuels and other high value-added products. The agricultural sector is currently undergoing global expansion, especially in relation to crops used for energy production as a strategy to reduce dependence on petroleum and mitigate the effects of climate change. Consequently, a similar expansion is expected in the amounts of agricultural and forestry residues generated. The conversion of these lignocellulosic biomasses using enzymes is likely to be a key technology in future biorefineries. However, in order to make the enzymatic conversion of biomass commercially viable, it is necessary to improve the efficiency of (hemi)cellulolytic enzymes production and reduce the costs of the enzymatic cocktails employed. The focus of this review is on recent developments in SSF processes for enzymes production, and the application of such techniques in the bioenergy sector. An overview of the enzymes required for the conversion of biomass, important SSF process variables related to the production of (hemi)cellulolytic enzymes, the bioreactors that have been used for this purpose, and novel SSF configurations is provided. It is hoped that the information gathered together here will assist in the development of SSF processes that enable efficient future production of the enzymes required for the conversion of biomass. © 2015 Elsevier Ltd. All rights reserved.

Heiligtag F.J.,ETH Zurich | Cheng W.,ETH Zurich | De Mendonca V.R.,Federal University of São Carlos | Suess M.J.,ETH Zurich | And 5 more authors.
Chemistry of Materials | Year: 2014

Self-assembly processes represent the most powerful strategy to produce complex materials with unique structural and compositional sophistication. Here we present such a self-assembly route to a three-component aerogel from preformed nanoparticle building blocks. Starting with a mixture of gold and anatase nanoparticles and tungsten oxide nanowires, controlled cogelation resulted in the formation of a macroscopic aerogel monolith with high specific surface area and porosity, remarkable transparency, and excellent crystallinity. The modular approach enables us to fine-tune the composition of the aerogels, and thus their properties, by choosing the appropriate building blocks and their relative concentration ratios. As an illustrative example, we show the targeted tailoring of the photocatalytic activity: the gold nanoparticles and the tungsten oxide nanowires both add their specific beneficial effects to the anatase aerogel matrix, leading to a superior performance of the three-component system. (Figure Presented). © 2014 American Chemical Society.

Luengo R.F.A.,Embrapa Vegetables | Calbo A.G.,Embrapa Instrumentation
Acta Horticulturae | Year: 2016

Vegetables need to be graded ('classified') according to agreed standards for each product in the market. The purpose of classification is to provide the seller and the buyer with a language, valid and safe, to enable agile negotiation of prices. In virtual commercialization, using digital communication tools, classification is no longer optional: it is indispensable. Classification prevents rework and misunderstandings related to inferior products with injuries and defects that induce contamination and losses associated with product disposal or reductions in sales value. In the Brazilian Federal District, as well as in other areas of Brazil, we observed that growers sell their vegetables, in most instances, without doing the work of sorting the product, a lack of investment that reduces their business performance. The perceived savings, in these cases, however, are transferred to the buyers who offer lower prices. The procedure as a whole is slower, involves rework and can cause increased costs and losses away from the farm, besides some reduction in freshness. In this work, 30 producers of typical vegetables of the Federal District, 75% of whom trade their vegetables without the use of classification, were studied. The possibility of using simple classification with minimal handling, using packaging containers arranged on a transporter was demonstrated. The proposed sorting alternative indicated that more growers could start sorting their vegetables for commercialization and achieve better profitability.

Luengo R.F.A.,Embrapa Vegetables | Calbo A.G.,Embrapa Instrumentation
Acta Horticulturae | Year: 2016

Several types of boxes are being used as accessories to harvest vegetables in Brazil. This adds to the complexity of operations for smallholders, whose family business is to cultivate several species of vegetables simultaneously, while supporting an oppressive workload. To improve the yield and quality of the produced vegetables, a constant concern is to simplify and streamline the procedures, to leverage the business, through the proper use of equipment, supplies and the family working capacity. In this study we made visits to farms and collected quantitative and qualitative information about boxes and other accessories used to harvest by vegetables growers in the Federal District. Some procedures used to monitor the harvest made by the growers were harvest velocity, distance traveled by the laborer, number and type of packages and type of accessory transporter used for harvesting and transportation. Accessories for harvest of vegetables used in this study included a new platform for harvest, buckets, plastic boxes, wheelbarrows and baskets. It is concluded that it is possible to improve harvesting yield and to reduce postharvest losses, while improving the freshness of vegetables up to their marketing, by making use of new minimal handling procedures, using arrays of boxes, and classification procedures, over a low cost movable harvest platform.

Rodriguez-Zuniga U.F.,Embrapa Instrumentation | Rodriguez-Zuniga U.F.,University of Sao Paulo | Couri S.,Federal University of Rio de Janeiro | Neto V.B.,Embrapa Instrumentation | And 3 more authors.
Bioenergy Research | Year: 2013

The conversion of agro-industrial residues, such as sugarcane bagasse, into high-value products and renewable energy, within the biorefinery concept, is a potential alternative towards the sustainable management of these resources. This work evaluates the production of cellulolytic enzymes by a selected strain of Aspergillus niger cultivated in sugarcane bagasse under solid-state fermentation using an instrumented lab-scale bioreactor. The effects of environmental factors including the type of substrate and medium composition, as well as the operational conditions (air flow rate, inlet air relative humidity, and initial substrate moisture content) on the production of the enzymatic complex were evaluated using statistical design tools. Significant increases in FPase, endoglucanase, and xylanase activities were achieved under the optimized conditions predicted by the models, with values of 0. 88, 21. 77, and 143. 85 IU/g of dry solid substrate, respectively, representing around ten-, four-, and twofold increases compared to the activities obtained under the initial growth conditions. This demonstrates the importance of evaluating environmental and operational criteria in order to achieve efficient enzyme production. The crude enzymatic extract obtained under optimized conditions was employed for enzymatic hydrolysis of pretreated sugarcane bagasse. Approximately 13 % of total reducing sugars, and a glucose concentration of 2. 54 g/L, were obtained after 22 h of hydrolysis of steam exploded sugarcane bagasse, indicating that the enzymatic cocktail produced has good potential for use in the conversion of biomass. © 2012 Springer Science+Business Media, LLC.

Senesi G.S.,CNR Institute of Neuroscience | Carrara I.,Impresa Ing. Antonio Resta e C. Srl | Nicolodelli G.,Embrapa Instrumentation | Milori D.M.B.P.,Embrapa Instrumentation | De Pascale O.,CNR Institute of Neuroscience
Microchemical Journal | Year: 2016

The laser cleaning process combined with laser-induced breakdown spectroscopy (LIBS) were applied to restore and characterize altered limestones of the ancient jamb of the historic entrance gate of Castello Svevo, Bari, Italy. This area of the masonry blocks of the limestone castle was chosen because of its evident degradation with an apparent deposit of black crusts. The combination of a Q-switched Nd:YAG pulsed laser with the diagnostics typical of the LIBS technique was shown to be very effective for monitoring, controlling and characterizing the laser cleaning process of limestone. The different elemental compositions of the black encrustations covering the stone surface and the underlying stone allowed to evaluate and avoid over-cleaning and/or under-cleaning. Further, coupling LIBS to the cleaning process provided important information about the optimal experimental conditions to be used for evaluating the conservation status and determining the most proper cleaning restoration procedure before operating the consolidation of the blocks. Thus a sufficient removal of unwanted layers could be achieved without modifying the surface underneath and ameliorating the effectiveness of traditional cleaning techniques. In this work, the elemental composition of the ablated black crust and the underlying stone were determined by the spectroscopic study of plasma emitted from either a single pulse (SP) or a double pulse (DP) LIBS configuration. With respect to SP LIBS, a marked enhancement of the signal emission was observed by DP-LIBS used after a previous stratigraphic DP-LIBS assessment of the cleaning depth. © 2015 Elsevier B.V.

Loading Embrapa Instrumentation collaborators
Loading Embrapa Instrumentation collaborators