Development of a calibration methodology to improve the on-site non-destructive evaluation of concrete durability indicators

This paper addresses the use of non-destructive testing (NDT) methods to assess indicators for both the concrete durability (porosity, degree of saturation) and mechanical properties (elasticity modulus, compressive strength) of reinforced concrete structures. NDT results, called “observables”, are obtained by means of ultrasonic or electromagnetic methods and then correlated with these mechanical and durability indicators. The conversion model used to transform observables into indicators depends on the actual concrete mix design. If this conversion model is unavailable for the reinforced structure under study, then the evaluation may be inadequate due to high uncertainty on the results. This paper proposes a calibration methodology to derive a conversion model appropriate for the structure by use of a minimum number of cores in order to improve the on-site evaluation. A motorway bridge is tested and characterized by NDT, after which some cores are extracted for calibration and others for validation. The cores are subsequently non-destructively characterized in the laboratory and/or used to determine indicators by means of standardized destructive methods. The non-destructive calibration protocol on cores is presented first. Next, NDT results recorded in situ and on the corresponding core are compared. Also, durability indicators deduced from on-site NDT measurements in addition to calibration are compared with reference durability indicators that have been independently determined by standard destructive methods. Results obtained by analyzing more than 1600 data fully validate the tested calibration methodology.     

Partition of proteins in the aqueous guar/dextran two-phase system

The partition of proteins (bovine serum albumin, β-lactoglobulin, micellar casein) has been examined in the guar/dextran aqueous two-phase system. The influence of parameters like pH, ionic strength (NaCl), and polymer concentration has been investigated while the protein concentration was increased up to 2% w/w. For globular proteins (bovine serum albumin, β-lactoglobulin) the general trends of partitioning established in the literature with other systems like polyethyleneoxide/dextran were nearly verified. The dextran-rich bottom phase was found to be slightly more concentrated in protein than the guar-enriched top one. However, micellar casein displayed a different behavior, giving a more uneven partition and phase separation phenomena at concentrations above 0.5% w/w. This difference has been attributed to the larger size of the particle. Meanwhile, the modifications of the guar/dextran phase diagram have been investigated. It was shown that the addition of globular protein or micellar casein up to 2% w/w did not affect the thermodynamic features of this system.     

A tool for task-based knowledge and specification acquisition

Knowledge acquisition has been identified as the bottleneck for knowledge engineering. One of the reasons is the lack of an integrated methodology that is able to provide tools and guidelines for the elicitation of knowledge as well as the verification and validation of the system developed. Even though methods that address this issue have been proposed, they only loosely relate knowledge acquisition to the remaining part of the software development life cycle. to alleviate this problem, we have developed a framework in which knowledge acquisition is integrated with system specifications to facilitate the verification, validation, and testing of the prototypes as well as the final implementation. to support the framework, we have developed a knowledge acquisition tool, TAME. It provides an integrated environment to acquire and generate specifications about the functionality and behavior of the target system, and the representation of the domain knowledge and domain heuristics. the tool and the framework, together, can thus enhance the verification, validation, and the maintenance of expert systems through their life cycles. © 1994 John Wiley & Sons, Inc.     

The potential impact of current animal research on the meat industry and consumer attitudes towards meat

Progress in animal nutrition, reproduction, quantitative genetics, and the development of molecular genetics, proteomics, and functional genomics open new perspectives for the meat sector. The most promising developments include a wider utilisation of molecular markers, the possibilities of semen sexing and the targeted use of nutrition to modify the composition of meat. The increased use of biotechnology will have a considerable impact on the economics of production of meat and further processed products. New technologies will increase the possibilities for product differentiation and improve homogeneity of live animals. The consumer and society in general will influence the direction of these developments. This review will focus on the long-term impact of new technologies for the meat production chain.     

Effects of the Hot Electron Interchange Instability on Plasma Confined in a Dipolar Magnetic Field

The Levitated Dipole Experiment (LDX) explores confinement and stability of plasma created within the dipole field of a strong superconducting magnet. During initial experiments, long-pulse, quasi-steady state discharges that last more than 10 s and have peak beta of more than 20% are studied. The plasma is created by multi-frequency electron cyclotron resonance heating (ECRH) at 2.45 and 6.4 GHz. A population of energetic electrons, with mean energies above 50 keV, dominates the plasma pressure. Creation of high pressure, high beta plasma is possible only when intense hot electron interchange (HEI) instabilities are stabilized by sufficient neutral gas fueling. The instabilities resonate with the magnetic drift motion of the energetic electrons and can cause rapid radial transport. Measurements of the electrostatic and magnetic fluctuations of the HEI instability are described along with observations of the instability’s spectral characteristics. Fluctuations of the outer poloidal field induced by the HEI show a rapid evolution of the perturbed pressure profile.      

The preparation of hybrid trimer by cyclo-oligomerization of TDI and HDI and its curing process with polyols to form elastic PU coating

The hybrid cyclic isocyanate trimer with appropriate functionality and good solvent tolerance which can be used as a building block to construct polyurethane (PU) coatings was prepared by cyclo-oligomerization of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI). Among all the tested catalysts, the self-made catalyst 3-(trimethylammonio)propyl carbonate (Cat. 4) was found to possess enough catalytic efficiency to confirm the NCO conversion to reach about 50% with both high (1 wt%) and low (0.25 wt%) catalyst loading at low temperature (40°C). The IR and NMR results proved the formation of a hybrid trimer, while HPLC results showed hybrid TDI/HDI trimer predominated in the product and only trace amounts of TDI monomer (<0.5 wt%) and oligomer with higher degree of polymerization (DP) remained. Furthermore, the formed hybrid oligomer exhibited excellent solvent tolerance to benzene, chlorinated, and acetate solvents. Consequently, Cat. 4 was demonstrated to be a suitable catalyst for cyclo-oligomerization since it not only possessed enough catalytic efficiency at low temperature but also hardly resulted in higher DP oligomer. Furthermore, the curing process with PTHF-r-PEO polyol was conducted as a pilot experiment to form PU coatings at room temperature. The disappearance of NCO group in IR spectrum as well as higher storage modulus against loss modulus implied the successful curing process. The strain–stress test showed the high tensile strength of formed PU coating, whereas the rheological test and dynamic mechanical analyzer proved the formed PU coating was a typical elastic material with good crosslink structure. These results indicate the promising potential of formed PU made from hybrid TDI/HDI trimer for coating applications.     

Zn speciation in the organic horizon of a contaminated soil by micro-X-ray fluorescence, micro- and powder-EXAFS spectroscopy, and isotopic dilution

Soils that have been acutely contaminated by heavy metals show distinct characteristics, such as colonization by metal-tolerant plant species and topsoil enrichment in weakly degraded plant debris, because biodegradation processes are strongly inhibited by contamination. Such an organic topsoil, located downwind of an active zinc smelter and extremely rich in Zn (approximately 2%, dry weight), was investigated by X-ray diffraction, synchrotron-based X-ray microfluorescence, and powder- and micro-extended X-ray absorption fine structure (EXAFS) spectroscopy for Zn speciation and by isotopic dilution for Zn lability. EXAFS spectra recorded on size fractions and on selected spots of thin sections were analyzed by principal component analysis and linear combination fits. Although Zn primary minerals (franklinite, sphalerite, and willemite) are still present (approximately 15% of total Zn) in the bulk soil, Zn was found to be predominantly speciated as Zn-organic matter complexes (approximately 45%), outer-sphere complexes (approximately 20%), Zn-sorbed phosphate (approximately 10%), and Zn-sorbed iron oxyhydroxides (approximately 10%). The bioaccumulated Zn fraction is likely complexed to soil organic matter after the plants' death. The proportion of labile Zn ranges from 54 to 92%, depending on the soil fraction, in agreement with the high proportion of organically bound Zn. Despite its marked lability, Zn seems to be retained in the topsoil thanks to the huge content of organic matter, which confers to this horizon a high sorption capacity. The speciation of Zn in this organic soil horizon is compared with that found in other types of soils.