Comparison between Measured and Model ( LBLand BRE) Predicted Infiltration Rates for a Passive Solar Test Cell

The pressurization technique is applied to the test cell at the JRC, Ispra, and important parameters for the LBL and BRE air infiltration models are calculated. The predictions of these models are compared with the tracer gas (SF₆) measurements. The differences between measured and predicted values of the air infiltration rates axe quite large. When the model parameters calculated from the tracer gas measurements are used, both models predict infiltration rates in good agreement with the field measurements. This means the physical models are acceptable but there is a need to refine the procedure for determination of model parameters.     

REVERSING A LEXICALLY BASED PARSER FOR GENERATION

It is practically advantageous and theoretically meaningful to base both a natural language generator and a parser on the same linguistic data. Neutrality of the representation can be advocated for all unification-based grammars. Yet the basic process in generation can also have several points in common with parsing. Specifically, not only is a unification-based approach proposed that produces from the initial semantic representation the sentence together with a functional structure but also the process is based on an adaptation of the concept of chart, which we call bi-chart (bidimensional chart). The chart is cast over the semantic representation and not over the string but has the same qualities as the classic one. The other relevant point here is that most of the data used in the process are distributed throughout the lexicon, and this results in a very flexible system.     

On efficiency of both single fuel cells and stacks I

A method to estimate the efficiency of a stack of several identical cells is described on the basis of the electrochemical behavior of a single cell. Efficiency of fuel cell stacks is defined by means of a combination of semi-empirical models of polarization curves and dimensionless variables such as reaction extent and utilization. The connection of flows among the cells is basically divided in two extreme cases and one intermediate case. Higher efficiencies are obtained when the same main flow (both anodic and cathodic) passes consecutively through the stack cells (Chain Flow), because it is favored thermodynamically. It is less favored when the main flow is strictly divided among all the cells (Separate Flow). In the intermediate case, the main flow is divided among all the stack cells and all the outlets are collected in one flow. The latter can spontaneously evolve to the more thermodynamically stable behavior of Chain Flow.     

Nonenzymatic Browning in Liquid Model Systems of High Water Activity: Kinetics of Color Changes due to Caramelization of Various Single Sugars

The kinetics of color changes due to caramelization of various single sugar solutions (fructose, xylose, glucose, maltose, lactose, and sucrose) of water activity adjusted to 0.90 (by adding NaCl) and heated at various temperatures (45–65°C) was studied. A zero-order and a “mixed”-order kinetic model were satisfactorily used to describe the rate of color formation. Fructose and xylose solutions browned much more rapidly than those of maltose, glucose, lactose or sucrose. Activation energies for color development of fructose and xylose were in the range 25–30 kcal/mole, while for lactose and maltose they were 35–48 kcal/mole. Lowering of pH inhibited caramelization browning of sugar solutions. The role of hydrolysis in the browning of heated sucrose solutions was studied.     

Morphology of the poly(vinyl alcohol)–poly(vinyl acetate) copolymer in macrodefect-free composites: a 13C magic-angle-spinning nuclear magnetic resonance and 1H spin-diffusion study

A study was made of the macrodefect-free (MDF) composite based on aluminate cement and a poly(vinyl alcohol)–poly(vinyl acetate) (PVAc) copolymer by ¹³C cross-polarization magic-angle-spinning nuclear magnetic resonance. The spectra were run on both the copolymer and the MDF composite in order to observe the atomic environments of the carbon nuclei. An analysis of the intramolecular hydrogen bonds showed a stronger modification in the sample containing CaAl₂O₄ (CA) than in that containing Ca₃Al₂O₆ (C₃A). From the spectra, it was seen that deacetylation had occurred, and that there was interaction between acetate groups and the calcium and aluminium ions. Proton relaxation times both in the laboratory frame, T ₁(H), and in the rotating frame, T1ρ(H), were exploited for the study of the dimension of the polymer matrix in MDF composites. An extended interphase was identified in the composite containing CA. A comparison with the behaviour of the composite based on silicates Ca₃SiO₅–PVAc highlights the better mixing of the phases in the MDF composites containing CA. This revised version was published online in November 2006 with corrections to the Cover Date.     

Analysis of the interface conditions during drying of rice

The influence of the relative air humidity on the surface conditions of rice grain during drying was investigated. It was found that the equilibrium condition given by the desorption isotherm of the product is not valid over the whole range of relative humidity analysed. While this condition was verified with air of high relative humidity (between 43 and 59% for drying temperatures ranging from 40 to 70°C), the experimental results indicated that the surface moisture approaches the monolayer value given by the Brunauer, Emmett and Teller (BET) desorption isotherm when drying takes place with air of low relative humidity (7 and 14% for the same temperature range). An explanation of these facts is suggested taking into account the high value of the heat of desorption associated with the monolayer moisture content of the product under investigation. Finally, a method based on the Fick's second law solution when the time of drying becomes large enough is proposed to evaluate the surface moisture content of the grain independently of the conditions of the air drying.     

ENTEROBACTERIACEAE IN ICE CREAM SOLD AT RETAIL IN TENERIFE, SPAIN

Ice cream is a dairy product which favors the growth of microorganisms and can be exposed to contamination during handling while being sold at the retail market. The presence of microorganisms belonging to the Enterobacteriaceae family was studied in 67 ice cream samples in the province of Santa Cruz de Tenerife. All the samples showed positive counts, of which 82.1% revealed microbiol counts of > log 3 - < log 5 CFU/g. The isolated species identified (as percent of total) were: Klebsiella pneumoniae, 34.8; Enterobacter aerogenes, 19.3; Enterobacter cloacae, 11.1; Enterobacter aglomerans, 11.6; Escherichia coli and Salmonella arizonae, 2.6; Citrobacter freundii, 1.3; and Serratia marcenscens, 0.7.     

Determination of Individual Simple Sugars in Aqueous Solution by Near Infrared Spectrophotometry

An approach is presented for using near infrared region (NIR) spectrophotometry to determine the individual simple sugars (glucose, fructose, and sucrose) in aqueous solutions ranging from 3 - 52% (w/w). The 95% confidence limits of the method for glucose, fructose, and sucrose were ≦ 1.3, 1.0, 0.9%, respectively.