Models in a Bayesian framework for inactivation of pectinesterase in a commercial enzyme formulation by pulsed electric fields

The inactivation of pectinesterase (PE) in a commercial enzyme formulation (CEF) under pulsed electric fields (PEF) was studied. Samples of an aqueous solution of the CEF were exposed to exponential waveform pulses for up to 16 ms at electric field intensities ranging from 5 to 24 kV cm^–1. Pulses were delivered in monopolar mode. The observed inactivation of the enzyme was described by several kinetics and regarding the input of electrical energy density (Q) models using Bayesian non-linear regression. Posterior distributions of the characteristic parameters for each kinetic model (based on the Hülsheger or the Weibull equation) and each Q model (based on exponential decay or the Weibull equation) were obtained. Kinetics models based on the Weibull equation showed better goodness and accuracy than the other models.     

Mathematical Modeling of a Continuous Vibrating Fluidized Bed Dryer for Grain

A mathematical model for the drying of grain in a continuous vibrating fluidized bed dryer was developed. Simple equipment and material models were applied to describe the process. In the plug-flow equipment model, a thin layer of particles moving forward and well mixed in the direction of the gas flow was examined. Mass and heat transfer within a single wet particle was described by effective transport coefficients. Assuming constant effective mass transport coefficient and thermal conductivity, analytical solutions of the mass and energy balances were obtained. The variation in both transport coefficients along the dryer was taken into account by a stepwise application of the analytical solution in space intervals with averaged coefficients from previous locations in the dryer. Calculation results were in fairly good agreement with experimental data from the literature. However, the results depend strongly on relationships used to determine the heat and mass transfer coefficients; because the results from correlations found in the literature vary considerably, the correlations should be adapted to the specific equipment in order to obtain reliable results.     

EFFECTS OF HEAT GENERATION-ABSORPTION AND CHEMICAL REACTION ON MAGNETOHYDRODYNAMIC FLOW IN A PERMEABLE MOVING PLATE: NETWORK NUMERICAL STUDY

This study addresses the transient heat and mass transfer problem by laminar flow of a Newtonian, viscous electrically conducting, and heat generating/absorbing fluid on a continuously moving permeable surface. It was carried out with the well-known network simulation method. The effect of the parameters involved in the process were analyzed, so the influence of the parameters is represented graphically for several cases. The dimensionless parameters used in this study are: chemical reaction parameter, Prandtl number, Grashof number, absorption coefficient or heat generation, Schmidt number, and Hartmann number. The results presented are important because of the relevance of the conclusions for the steady and transient cases. In the study, the flow was considered laminar and two-dimensional. In addition, the transverse magnetic field is uniform and viscous dissipation effects, Hall effect, and Joule heating are omitted.     

Catalytic behavior of vanadium-containing mesoporous silicas in the oxidative dehydrogenation of propane

Three series of vanadium-containing silica catalysts (2–7.6 wt% V) have been prepared by varying the synthesis method. In all cases, conversion values in the oxidative dehydrogenation of propane increase with the temperature, vanadium loading and reducibility. For impregnated and anchored catalysts, a relationship between the selectivity towards propene and the effective acidity, as determined in the dehydration of 2-propanol, can be established. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparative analysis of dental enamel polyvinylsiloxane impression and polyurethane casting methods for SEM research

Dental casting is a very common procedure for making high-quality replicas of paleo-anthropological remains. Replicas are frequently used, instead of original remains, to study both fossil and extant Primate teeth in morphological and metrical analyses. Several commercial products can be used in molds. This study analyzed SEM image resolution and enamel surface feature definition of tooth molds at various magnification levels and obtained, with both Coltène and 3M low-viscosity body polyvinylsiloxane impression, materials and polyurethane casts. Results, through comparison with the original teeth, show that both the negative molds and the positive casts are highly reliable in replicating enamel surfaces. However, positive cast quality is optimal for SEM observation only till the fourth consecutive replica from the original mold, especially at high SEM magnification levels.     

Characterisation of Grasp Quality Metrics

Robot grasp quality metrics are used to evaluate, compare and select robotic grasp configurations. Many of them have been proposed based on a diversity of underlying principles and to assess different aspects of the grasp configurations. As a consequence, some of them provide similar information but other can provide completely different assessments. Combinations of metrics have been proposed in order to provide global indexes, but these attempts have shown the difficulties of merging metrics with different numerical ranges and even physical units. All these studies have raised the need of a deeper knowledge in order to determine independent grasp quality metrics which enable a global assessment of a grasp, and a way to combine them. This paper presents an exhaustive study in order to provide numerical evidence for these issues. Ten quality metrics are used to evaluate a set of grasps planned by a simulator for 7 different robot hands over a set of 126 object models. Three statistical analysis, namely, variability, correlation and sensitivity, are performed over this extensive database. Results and graphs presented allow to set practical thresholds for each quality metric, select independent metrics, and determine the robustness of each metric,providing a reliability indicator under pose uncertainty. The results from this paper are intended to serve as guidance for practical use of quality metrics by researchers on grasp planning algorithms.     

The 2D wavelet transform on emerging architectures: GPUs and multicores

Because of the computational power of today??s GPUs, they are starting to be harnessed more and more to help out CPUs on high-performance computing. In addition, an increasing number of today??s state-of-the-art supercomputers include commodity GPUs to bring us unprecedented levels of performance in terms of raw GFLOPS and GFLOPS/cost. In this work, we present a GPU implementation of an image processing application of growing popularity: The 2D fast wavelet transform (2D-FWT). Based on a pair of Quadrature Mirror Filters, a complete set of application-specific optimizations are developed from a CUDA perspective to achieve outstanding factor gains over a highly optimized version of 2D-FWT run in the CPU. An alternative approach based on the Lifting Scheme is also described in Franco et al. (Acceleration of the 2D wavelet transform for CUDA-enabled Devices, 2010). Then, we investigate hardware improvements like multicores on the CPU side, and exploit them at thread-level parallelism using the OpenMP API and pthreads . Overall, the GPU exhibits better scalability and parallel performance on large-scale images to become a solid alternative for computing the 2D-FWT versus those thread-level methods run on emerging multicore architectures.     

Characterization of the glycerolipid composition of a high‐palmitoleic acid sunflower mutant

The glycerolipid composition of a high‐palmitoleic acid sunflower (Helianthus annuus L.) mutant accumulating up to 20% of n‐7 fatty acids was studied. This line produces oil with a complex triacylglycerol (TAG) composition, containing species that have not been previously identified in sunflower. In this regard, palmitoleic acid was esterified in an unexpected way in the three positions of the TAG molecules. The polar glycerolipid composition of the mutant was also studied, in order to identify and quantify the changes in membrane lipids imposed by the sunflower enzymatic machinery during the accumulation of the unusual n‐7 fatty acids. The high‐palmitoleic mutant accumulated important quantities of n‐7 fatty acids in the polar lipid fraction, especially in the phosphatidylcholine lipid class. However, the total polar lipid content of these lines was not affected. On the other hand, the mutations responsible for the n‐7 lipid accumulation induced an important decrease in the oil yield of the new mutant.