A Comparison Between Lime and Alkaline Hydrogen Peroxide Pretreatments of Sugarcane Bagasse for Ethanol Production

Pretreatment procedures of sugarcane bagasse with lime (calcium hydroxide) or alkaline hydrogen peroxide were evaluated and compared. Analyses were performed using 2³ factorial designs, with pretreatment time, temperature, and lime loading and hydrogen peroxide concentration as factors. The responses evaluated were the yield of total reducing sugars (TRS) and glucose released from pretreated bagasse after enzymatic hydrolysis. Experiments were performed using the bagasse, as it comes from an alcohol/sugar factory and bagasse, in the size, range from 0.248 to 1.397 mm (12–60 mesh). The results show that, when hexoses and pentoses are of interest, lime should be the pretreatment agent chosen, as high TRS yields are obtained for non-screened bagasse using 0.40 g lime/g dry biomass at 70 °C for 36 h. When the product of interest is glucose, the best results were obtained with lime pretreatment of screened bagasse. However, the results for alkaline peroxide and lime pretreatments of non-screened bagasse are not very different.     

Acquisition of deeper knowledge on the human plasma fatty acid profile exploiting comprehensive 2-D GC

The present research is focused on the use of comprehensive 2-D GC (GC x GC) for the elucidation of the human plasma fatty acid (FA) profile. The enhanced sensitivity, increased separation power and the formation of group-type patterns provided by GC x GC enabled the identification and quantification of a high number of both well known and unexpected FAs, for a total of 65 components. Peak assignment was, in most cases, supported by using pure standard compounds. The results attained demonstrated the usefulness of the multidimensional GC method in this fundamental field of research.     

Mixed ionic–electronic conducting (MIEC) ceramic-based membranes for oxygen separation

Although Nernst observed ionic conduction of zirconia–yttria solutions in 1899, the field of oxygen separation research remained dormant. In the last 30 years, research efforts by the scientific community intensified significantly, stemming from the pioneering work of Takahashi and co-workers, with the initial development of mixed ionic–electronic conducting (MIEC) oxides. A large number of MIEC compounds have been synthesized and characterized since then, mainly based on perovskites (ABO_3−δ and A₂BO_4±δ) and fluorites (A_δB_1−δO_2−δ and A_2δB_2−2δO₃), or dual-phases by the introduction of metal or ceramic elements. These compounds form dense ceramic membranes, which exhibit significant oxygen ionic and electronic conductivity at elevated temperatures. In turn, this process allows for the ionic transport of oxygen from air due to the differential partial pressure of oxygen across the membrane, providing the driving force for oxygen ion transport. As a result, defect-free synthesized membranes deliver 100% pure oxygen. Electrons involved in the electrochemical oxidation and reduction of oxygen ions and oxygen molecules respectively are transported in the opposite direction, thus ensuring overall electrical neutrality. Notably, the fundamental application of the defect theory was deduced to a plethora of MIEC materials over the last 30 years, providing the understanding of electronic and ionic transport, in particular when dopants are introduced to the compound of interest. As a consequence, there are many special cases of ionic oxygen transport limitation accompanied by phase changes, depending upon the temperature and oxygen partial pressure operating conditions. This paper aims at reviewing all the significant and relevant contribution of the research community in this area in the last three decades in conjunction with theoretical principles.     

Study of electrochromic devices with nanocomposites polymethacrylate hydroxyethylene resin based electrolyte

This paper reports the application of a polymethacrylate hydroxyethylene resin based electrolyte in electrochromic (EC) devices. The electrolyte is characterized by electrochemical impedance spectroscopy, visible spectroscopy, TGA, DSC, and DRX and tested as an ionic conductor in an EC device with the following configuration: Substrate/IZO/WO₃/Polymer Electrolyte/(CeO₂)TiO₂/IZO/Substrate. The electrolyte presents an ionic conductivity of 10^?7 S/cm at room temperature and TGA analysis show that electrolyte is thermally degraded at 200°C. The EC device based on this polymethacrylate hydroxyethylene resin electrolyte system shows memory effect and exhibits an excellent optical density. Copyright © 2011 John Wiley & Sons, Ltd.     

A Novel Route to the Synthesis of Mesoporous Titania with Full Anatase Nanocrystalline Domains

A porous, high surface area TiO₂ with anatase or rutile crystalline domains is advantageous for high efficiency photonic devices. Here, we report a new route to the synthesis of mesoporous titania with full anatase crystalline domains. This route involves the preparation of anatase nanocrystalline seed suspensions as the titania precursor and a block copolymer surfactant, Pluronic P123 as the template for the hydrothermal self-assembly process. A large pore (7–8 nm) mesoporous titania with a high surface area of 106–150 m²/g after calcination at 400°C for 4 h in air is achieved. Increasing the hydrothermal temperature decreases the surface area and creates larger pores. Characteristics of the seed precursors as well as the resultant mesoporous titania powder were studied using XRD analysis, N₂-adsorption/desorption analysis, and TEM. We believe these materials will be especially useful for photoelectrochemical solar cell and photocatalysis applications.     

Synthesis of Tetrahydro‐2(1H)quinazolinones,Cyclopenta[d]‐2(1H)pyrimidinones,and Their Thioxo Analogs from 2‐Trifluoroacetyl‐1‐methoxycycloalkenes

A series of six (8)‐alkyl‐4‐trifluoromethyl‐5,6,7,8‐tetrahydro‐2(1H)quinazolinones, 4‐trifluoromethyl‐cyclopenta[d]‐2(1H)pyrimidinones, and their thioxo analogs from the reaction of five β‐alkoxyvinyl trifluoromethyl ketones, derived from alkylated cyclohexanones and cyclopentanone with urea and thiourea, is reported. The reactions were carried out in a single step in propan‐2‐ol as solvent and boron trifluoride diethyl etherate as catalyst in 18–65% yield.     

Spectroelectrochemical study of the corrosion of a copper electrode in deaerated 1.0 M HCl solutions containing Fe(III): Effect of the corrosion inhibitor benzotriazole

The corrosion rate of a copper electrode in deaerated 1.0 M HCl by Fe(III) ions, in the absence and presence of benzotriazole (BTAH), has been evaluated through weight-loss experiments using a rotating disk electrode (RDE). The corrosion process is controlled by transport of the Fe(III) ions to the electrode surface both in the absence and presence of BTAH. The inhibiting action is initiated at BTAH concentrations around 10 mM and the Langmuir adsorption isotherm is obeyed in the BTAH concentration range from 10 to 45 mM with an apparent equilibrium adsorption constant of 10 M⁻¹. Above this concentration, the Langmuir plot is not obeyed due to the formation of a multilayer. The surface films formed during the corrosion process have been investigated by “in situ” and “ex situ” fluorescence and Raman spectroscopy and characterized as being composed of the polymeric [Cu(I)BTA] complex and [Cu(I)CIBTAH]₄, the former as an inner layer response for the corrosion inhibition process.     

Changes in degree of polymerization in the thermal degradation of polystyrene

The chain scission and volatilization processes which occur in the thermal degradation of polystyrene have been simulated by Monte Carlo procedures and the results have been compared with the degrees of polymerization, determined experimentally, of polystyrene samples degraded to different extents. The results of the calculations agree with random scission of the polymer chains at temperatures at which volatilization of simple molecules does not occur and with a degradation mechanism involving extensive deactivation of radicals through hydrogen abstraction from the body of polymer chains at temperatures at which volatilization does occur. The calculations also show that the molecularity index, i.e. the ratio between the weight average and the number average degrees of polymerization, tends to 2, independently of the degradation mechanism.     

Lime Pretreatment and Fermentation of Enzymatically Hydrolyzed Sugarcane Bagasse

Sugarcane bagasse was subjected to lime (calcium hydroxide) pretreatment and enzymatic hydrolysis for second-generation ethanol production. A central composite factorial design was performed to determine the best combination of pretreatment time, temperature, and lime loading, as well as to evaluate the influence of enzymatic loadings on hydrolysis conversion. The influence of increasing solids loading in the pretreatment and enzymatic hydrolysis stages was also determined. The hydrolysate was fermented using Saccharomyces cerevisiae in batch and continuous mode. In the continuous fermentation, the hydrolysates were concentrated with molasses. Lime pretreatment significantly increased the enzymatic digestibility of sugarcane bagasse without the need for prior particle size reduction. In the optimal pretreatment conditions (90 h, 90 °C, 0.47 g?lime/g bagasse) and industrially realistic conditions of hydrolysis (12.7 FPU/g of cellulase and 7.3 CBU/g of β-glucosidase), 139.6 kg?lignin/ton raw bagasse and 126.0 kg hemicellulose in the pretreatment liquor per ton raw bagasse were obtained. The hydrolysate from lime pretreated sugarcane bagasse presented low amounts of inhibitors, leading to ethanol yield of 164.1 kg?ethanol/ton raw bagasse.