Improved prediction model for time-dependent deformations of concrete: Part 1-Shrinkage

This paper is the first in a series of papers that present a new prediction model for creep and shrinkage of concrete, called for brevity the BP−KX model. This model represents an update and improvement of the BP model published in this journal in 1978–79. The improvement is possible because further experimental data became available in the literature and at the same time knowledge of physical concepts and mechanisms has improved. This first paper presents a prediction model for the mean (overall) shrinkage strain in cross-sections of long members, which takes into account the influence of environmental humidity, the effective thickness of the member, the effect of cross-section shape, the effect of age at the start of drying, and the effect of temperature. The proposed basic form of the shrinkage formulae is fustified by nonlinear diffusion theory for the movement of moisture through concrete. Extensive comparisons with important test data from the literature, altogether 23 data sets, reveal that the predictions are better than with the previous models. Statistics of prediction are also given. The main error of prediction arises from the estimation of the shrinkage parameters from concrete strength and composition. If limited short-time shrinkage data are available, the predictions can be greatly improved.

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Resume Ce rapport est le premier d’une série présentant un nouveau modèle de prédiction du fluage et du retrait du béton dénommé, pour abréger, modèle BKP. Ce modèle représente une mise à jour et une amélioration du modèle BP décrit dans ce journal en 1978/79. Des données expérimentales ultérieures disponibles dans la littérature, en même temps qu’une meilleure connaissance des concepts et mécanismes physiques, ont permis ce progrès. Ce premier rapport présente un modèle de prédiction pour une contrainte de retrait moyenne dans les sections transversales de longs éléments, qui prend en compte l’influence de l’humidité ambiante, l’épaisseur effective de l’élément, l’influence de la forme de la section, de l’age au début du séchage et de la température. On justifie l’expression de base des formules de retrait par la théorie de la diffusion non linéaire pour la circulation de l’humidité dans le béton. De vastes comparaisons avec d’importantes données d’essai prises dans la littérature-en tout 23 séries d’essai-ont montré que les prédictions étaient meilleures qu’avec les modèles précédents. On donne aussi des statistiques de prédiction. L’erreur de prédiction principale provient de l’évaluation des paramètres de retrait à partir de la composition et de la résistance du béton. Si l’on dispose de données de retrait limité, les prédictions peuvent être considérablement améliorées.

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Deceased 1989.     

Analyses of organic foulants in membranes fouled by pulp and paper mill effluent using solid-liquid extraction

Fouling of membranes is a serious problem in membrane technology. By characterizing the foulants in membranes it is possible to understand fouling and reduce it. However, the characterization of foulants, especially organic ones, is difficult. The purpose of this study was to find out whether there are any organic foulants such as extractives in the membranes, and if it is possible to identify them. Membranes of different materials and hydrophilicity were used in filtration of ground wood mill (GWM) circulation water during one month in an integrated pulp and paper mill, Solid—liquid extraction was employed to remove the extractives from the membranes and the characterization of them was carried out with a gas chromatograph. According to the results, there are extractives in the membranes and it is possible to characterize them. It seems that the fouling by extractives mainly comes from resin and fatty acids. In addition, some traces of lignans were found in the membranes. Moreover, the hydrophobic membranes contained more of these acids and lignans than the hydrophilic membranes.     

A Model for Power Consolidation

During pressure consolidation of powder compacts, particle rearrangement leading to nonrecoverable strain can be observed. In this study rearrangement is identified as a buckling mechanism that occurs in particle arches. The mechanism is initiated when the applied pressure generates a critical contact force at an arch within the powder compact. The consequence of the buckling is localized consolidation. The contact forces required to initiate this mechanism on a particle scale are evaluated. It is shown that this snap-through-buckle mechanism could play a significant role in powder consolidation.     

Surface characteristics of tubercle mass and graphitic residue in cast iron water pipelines

Graphitic residues from cast iron water mains were characterized by surface area measurements. The surface areas were about 4–5 times higher than those determined for reference graphite Samples. Their capacity to retain water equalled that of activated charcoal. Adsorption properties were examined by using methylene blue and rhodamine B. Under the conditions employed, methylene blue behaved as a cationic species whereas rhodamine B seemed to have little charge effects. Ferric iron was found to adsorb on graphitic residues in a pH-dependent manner. Surface characteristics of tubercle material that overlyes graphitized areas in cast iron pipes were examined by scanning electron microscopy. A high degree of particle aggregation was observed and the size distribution varied with the crystallinity of the tubercle components.     

Performance of SU-8 microchips as separation devices and comparison with glass microchips

Effective analytical performance of native, all-SU-8 separation microdevices is addressed by comparing their performance to commercial glass microdevices in microchip zone electrophoresis accompanied by fluorescence detection. Surface chemistry and optical properties of SU-8 microdevices are also examined. SU-8 was shown to exhibit repeatable electroosmotic properties in a wide variety of buffers, and SU-8 microchannels were successfully utilized in peptide and protein analyses without any modification of the native polymer surface. Selected, fluorescent labeled, biologically active peptides were baseline resolved with migration time repeatability of 2.3-3.6% and plate numbers of 112,900-179,800 m(-1). Addition of SDS (0.1%) or SU-8 developer (1.0%) to the separation buffer also enabled protein analysis by capillary zone electrophoresis. Plate heights of 2.4-5.9 microm were obtained for fluorescent labeled bovine serum albumin. In addition, detection sensitivity through SU-8 microchannels was similar to that through BoroFloat glass, when fluorescence illumination was provided at visible wavelengths higher than 500 nm. On the whole, the analytical performance of SU-8 microchips was very good and fairly comparable to that of commercial glass chips as well as that of traditional capillary electrophoresis and chromatographic methods. Moreover, lithography-based patterning of SU-8 enables straightforward integration of multiple functions on a single chip and favors fully microfabricated lab-on-a-chip systems.     

Comparison of requirements for using health claims on foods in the European Union,the USA,Canada, and Australia/New Zealand

Nutrition is recognized as one of the leading factors influencing the growing incidence of noncommunicable diseases. Despite society experiencing a global rise in obesity, specific populations remain at risk of nutrient deficiencies. The food industry can use health claims to inform consumers about the health benefits of foods through labeling and the broader promotion of specific food products. As health claims are carefully regulated in many countries, their use is limited due to considerable investments required to fulfill the regulatory requirement. Although health claims represent a driving force for innovation in the food industry, the risk of misleading of consumers need to be avoided. The health claim scientific substantiation process must be efficient and transparent in order to meet the needs of companies in the global market, but should be based on strong scientific evidence and plausible mechanisms of actions, to ensure highest level of consumer protection. The objective of this review is to compare the possibilities for using health claims on foods in the European Union, the USA, Canada, and Australia and New Zealand. In particular, we focused on differences in the classification of claims, on the scientific substantiation processes and requirements for health claims use on foods in the selected regions. Reduction of disease risk (RDR) claims are associated with relatively similar procedures and conditions for use, whereas several notable differences were identified for other types of claims. In all cases, RDR claims must be approved prior their introduction to the market, and only a few such claims have been authorized. Much greater differences were observed concerning other types of claims.     

Comparison of atmospheric deposition of copper, nickel, cobalt, zinc, and cadmium recorded by Finnish peat cores with monitoring data and emission records

This study aims to determine the extent to which the accumulation rates of Cu, Ni, Co, Zn, and Cd in peat cores agree with established histories of atmospheric emission from local pointsources. Metals accumulating in three Finnish peat cores with known metal deposition histories have been measured using inductively coupled plasma-sector field mass spectrometry. Samples were age-dated using both 210Pb and 14C (bomb pulse curve). At the Outokumpu (OUT) site as well as the low-background site Hietaj?rvi (HIJ), 210Pb age dates are in excellent agreement with the 14C bomb pulse curve method results, and the precision is between 1 and 10 years for most of the samples; at the Harjavalta (HAR) site, precision is > 6 years. Mean regional "background" concentrations have been calculated from deeper peat layers of the HIJ site (microg g(-1)): Cu, 1.3 +/- 0.2 (n = 62); Co, 0.25 +/- 0.04 (n = 71); Cd, 0.08 +/- 0.01 (n = 23); and Zn, 4 +/- 2 (n = 40). For layers accumulated within the past 100 years, accumulation rates (ARs) have been calculated. At sites with < 0.06 g m(-2) cumulative Ni inventory (HIJ and OUT), ARs of Cu and Co trace the known metal deposition histories very well. At HAR, where metal inventories are much greater, Cu and Co are mobile. ARs of Zn were between 3 and 30 mg m(-2) year(-1) and those of Cd between 24 and 140 microg m(-2) year(-1) at all sites and are independent of the chronology of their inputs from the atmosphere.     

Toward a consistent evaluative framework for POP risk characterization

The purpose of Annex E in the Stockholm Convention (SC) on Persistent Organic Pollutants (POPs) is to assess whether a chemical is likely, as a result of its long-range environmental transport, to lead to significant adverse human health or environmental effects, such that global action is warranted. To date, risk profiles for nominated POPs have not consistently selected assessment endpoints or completed mandated risk characterizations. An assessment endpoint hierarchy is proposed to facilitate risk characterization for the implementation of the SC. The framework is illustrated for a nominated POP, hexabromocyclododecane (HBCD), using three risk estimation methods. Based on current monitoring and toxicity data, the screening-level results indicate that humans and ecological receptors in remote regions such as the Arctic are unlikely to experience significant adverse effects (i.e., low risk) due to long-range environmental transport of HBCD. The results for birds are more uncertain than the results for fish and mammals due to the paucity of avian toxicity data. Risk characterization results for HBCD and for some listed POPs are compared to illustrate how the proposed methods can further assist decision-making and chemical management.     

Potential of Bacillus cereus for producing an emetic toxin,cereulide, in bakery products: quantitative analysis by chemical and biological methods

A method for the direct quantitative analysis of cereulide, the emetic toxin of Bacillus cereus, in bakery products was developed. The analysis was based on robotized extraction followed by quantitation of cereulide by liquid chromatography-mass spectrometry and an assay of toxicity by the boar sperm motility inhibition test. The bioassay and the chemical assay gave comparable results, demonstrating that the extracted cereulide was in a biologically active form. Cereulide was formed when cereulide-producing B. cereus strains were present at > or = 10(6) CFU/g in products with water activity values of > 0.953 and pHs of > 5.6. Rice-containing pastries accumulated high contents of cereulide (0.3 to 5.5 microg/g [wet weight]) when stored at nonrefrigeration temperatures (21 to 23 degrees C). Cereulide was not formed in products stored at refrigeration temperatures (4 to 8 degrees C). Cereulide is not inactivated by heating during food processing. Therefore, direct analysis of this toxin in food is preferable to cultivating methods for assessing the risk of food poisoning by emetic B. cereus.