Fed‐batch cultures of phaffia rhodozyma in xylose‐containing media made from wood hydrolysates

Abstract

Eucalyptus wood samples were treated with 3% aqueous sulphuric acid to obtain xylose‐containing solutions. The liquors from treatments were neutralized, contacted with charcoal and supplemented with nutrients to obtain culture media suitable for proliferating the carotenoid‐producing yeast, Phaffia rhodozyma NRRL Y‐17268. Two fed‐batch strategies (with continuous or intermittent feeding) were assayed as operational procedures for improving the carotenoid production. Biomass concentration of 10.3 g cells/L and volumetric pigment concentration of 8.15 mg total carotenoids/L (with 7.19 mg astaxanthin/L) were reached with continuous feeding, whereas improved results (30.6 g cells/L and 33.5 mg total carotenoids/L with 30.5 mg astaxanthin/L) were obtained with intermittent feeding.     

Deposition and photo-induced electrical resistivity of dip-coated NiO thin films from a precipitation process

Thin films of the semiconductor NiO are deposited using a straightforward combination of simple and versatile techniques: the co-precipitation in aqueous media along with the dip- coating process. The obtained material is characterized by gravimetric/differential thermal analysis (TG–DTA) and X-ray diffraction technique. TG curve shows 30 % of total mass loss, whereas DTA indicates the formation of the NiO phase about 578 K (305 °C). X-ray diffraction (XRD) data confirms the FCC crystalline phase of NiO, whose crystallinity increases with thermal annealing temperature. UV–Vis optical absorption measurements are carried out for films deposited on quartz substrate in order to avoid the masking of bandgap evaluation by substrate spectra overlapping. The evaluated bandgap is about 3.0 eV. Current–voltage (I–V) curves measured for different temperatures as well as the temperature-dependent resistivity data show typical semiconductor behavior with the resistivity increasing with the decreasing of temperature. The Arrhenius plot reveals a level 233 meV above the conduction band top, which was attributed to Ni²⁺ vacancy level, responsible for the p-type electrical nature of NiO, even in undoped samples. Light irradiation on the films leads to a remarkable behavior, because above bandgap light induced a resistivity increase, despite the electron–hole generation. This performance was associated with excitation of the Ni²⁺ vacancy level, due to the proximity between energy levels.     

Varietal discrimination of Chilean wines by direct injection mass spectrometry analysis combined with multivariate statistics

A simple, direct injection, electrospray ionization Fourier transform mass spectrometry (ESI FT-MS) method, in combination with multivariate statistics, was used for the characterization and sorting of Chilean wines. 47 commercial red wines labelled as Cabernet Sauvignon, Carménère, Syrah, and Pinot noir, and 25 white wines of the varieties Chardonnay and Sauvignon blanc were diluted, directly infused into the mass spectrometer, and analyzed in negative ion mode. The signature ions used for statistical analyses were manually filtered out from the signals with m/z ratios over 10%. The results of principal component analysis allowed a good sorting of white wines, but not so in the case of reds. The main three principal components explained 96.82% and 85.65% of the variance for white and red wines, respectively. Instead, linear discriminant analysis, allowed the correct discrimination of 100.00% of white and 95.74% of red samples. The validation of these results using the leave-one-out cross-validation method gave lower percentages of correct classification (76.00% and 61.70% of white and red samples respectively), suggesting that some of the wine samples analyzed might have been blends of more than one variety. Consequently, ESI FT-MS direct injection analysis of wines can be used for sample discrimination, but requires a stronger mathematical model built with spectral information of pure and blended samples before improving the percentages of classification.     

Automatic categorisation of comments in social news websites

The use of the social web has brought a series of changes in the way how content is created. In particular, social news sites link stories and the different users can comment them. In this paper, we propose a new method based on different features extracted from the text able to categorise the comments. To this end, we use a combination of statistical, syntactic and opinion features and machine-learning classifiers to classify a comment within three different categorisation types: the focus of the comment, the type of information contained in the comment and the controversy level of the comment. We validate our approach with data from ‘Menéame’, a popular Spanish social news site.     

3D reconstruction of cultural heritages: Challenges and advances on precise mesh integration

Several methods perform the integration of multiple range scans of an object aiming the generation of a reconstructed triangle mesh; however, achieving high fidelity digital reconstructions is still a challenge. That is mostly due to the existence of outliers in the acquired range data, and their harmful effects on the integration algorithms. In this work, we first discuss artifacts usually found on real range data captured with 3D scanners based on laser triangulation. Following that there is the assessment of two widely used volumetric integration techniques (VRIP and Consensus Surface) and our suggested improvements. We also present a novel, hybrid approach that combines strengths from both VRIP and Consensus Surface, named IMAGO Volumetric Integration Algorithm (IVIA). Our novel algorithm adds new ideas while improving the detection and elimination of artifacts. Further, IVIA works in close cooperation with the subsequent hole filling process, which greatly improves the overall quality of the generated 3D models. Our technique leads to better results when assessed in different situations, when compared to VRIP, Consensus Surface, and also to a well known state-of-the-art surface-based method, Poisson Surface Reconstruction.     

Analysis of the indoor GPS system as feedback for the robotic alignment of fuselages using laser radar measurements as comparison

The alignment of aircraft fuselages in the aerospace sector is currently done either manually or by complex, expensive automated systems. The manual process introduces a significant production delay and the automated systems are purpose-built and have limited flexibility, apart from its financial drawback. This work proposes a low-cost, high-flexibility system and, as part of it, evaluates the performance of a Rotary-Laser Automatic Theodolite (R-LAT) as a feedback source for the adaptive robot control of an anthropomorphic manipulator. In the proposed solution the robot carries a fuselage barrel and aligns it with respect to a second barrel. A high accuracy, frequency-modulated laser equipment is used to generate the reference system for the procedure. The measurements of the R-LAT are then verified with the frequency-modulated laser equipment in order to determine the linear and angular alignment tolerances achieved by the robot/R-LAT closed loop in a predefined work envelope. A throughout, step-by-step analysis of the measuring procedure is carried out to allow the recognition of error sources and thus the determination of an optimized method. These results identify the operation boundaries of the R-LAT within the process and yield its best configuration for the intended purpose. Using the EN ISO 9283 robot evaluation standard, the closed loop system was found to attain the nominal position with an average accuracy of 0.38 mm and 0.01°, contrasting with an average accuracy of 4.53 mm and 0.21° when the robot was operating in an open loop configuration.