Estimates on the intake of food additives in Finland

An estimation of the intakes of 30 food additives in Finland was conducted combining analytical data, food balance sheets, import and export statistics. The results indicated that most calculated average food additive intakes were well below the ADI values and internationally at an acceptable level. The intakes of nitrates, nitrites, saccharin and cyclamates were above or close to the respective ADI values. More studies are planned on these substances in order to establish possible special risk groups.     

A straightforward formalization of the relational model

There has been a lot of recent interest in the formalization of the relational data model (RDM). Many approaches may be characterized as ones oriented mainly towards declaring the components of the RDM and their interrelationships. Other approaches provide also a tool for manipulating the components of RDM so that research topics on the model can be specified exactly. Usually the latter approaches are based on formal specification methods such as denotational semantics or abstract data types. However some in the data base community find them quite complex and cumbersome.The goal of the approach of this paper is of the latter kind. However, special attention is being paid to avoid the complexity of the formal specification methods because our notations and definitions are based on set theory. We attempt to provide an exact, convenient and general tool for specifications and proofs concerning various topics like relational query languages, query optimization, relational data base restructuring, data base design, etc.     

Survival of Escherichia coli phage T7 in different water types

The survival of coliphage T7 was investigated in different water types, at 3 and 20°C, in samples taken both in winter and in summer. The results were analysed using the analysis of variance. The results showed that survival was generally good, although there were differences in inactivation rates between water types. The survival was better at the lower temperature, but there were differences between Van't Hoff coefficients in different waters. The season of sampling affected survival in several ways, indicating fluctuations in water quality. There were deviations from exponentiality in the inactivation rates.     

Worker allocation in make-to-order assembly cells

Assembly in the make-to-order manufacturing of large variable products is usually organized as a cell in which a team of workers operates. Several products are assembled in parallel and in sequence, so that the number of workers assembling a product may vary. The release times and due dates of products are determined by a higher level production plan. It is important to meet the due dates and use the workforce efficiently. The objective of the study described here is to optimize the allocation of workers to the products, so that the timing constraints are met, while the labor costs are minimized. Although the number of workers assembling a product can be varied, changing it involves start-up costs while the workers familiarize themselves with a new job, and a suboptimal number of workers reduce the productivity of work. These work efficiency characteristics are implemented in the optimization model presented. The developed model is a mixed integer linear program. The characteristics of the model are discussed and illustrative solutions and experimental results are provided.     

Specificity improvement of a recombinant anti-testosterone Fab fragment by CDRIII mutagenesis and phage display selection

The monoclonal antibodies so far developed by hybridoma technology have not had high enough specificity or affinity to distinguish the closely related steroid hormones in routine clinical assays. We have employed random mutagenesis and phage display approaches to improve the specificity of one anti-testosterone monoclonal antibody (3-C4F5). The affinity of the antibody is 0.3 x 10(9) M(-1) and the cross- reactivities with most of the related steroids are low. However, the antibody cross-reacts about 1% with dehydroepiandrosterone sulfate (DHEAS) and owing to the high DHEAS serum concentration this is about 1000-fold too high for clinical immunoassays. The complementarity- determining regions (CDRs) of the heavy and light chains, which were predicted by molecular modelling to be in close contact with the testosterone (TES) ligand, were randomized and mutant Fab libraries were cloned into a phagemid vector. Binders were selected by a competitive panning procedure. By combining the identified light and heavy chain CDRIII mutations the TES affinity was preserved at the wild- type level but DHEAS cross-reactivity was decreased to 0.03%. An important finding was that by the competitive panning procedure the overall binding specificity of the 3-C4F5 antibody was refined, since the cross-reactivities to related steroids were also significantly decreased in the combined mutant.      

Optimal tool magazine operation. Part 2: rotating magazines with buffered tool change

The paper examines the minimisation of the tool change waiting time of numerically controlled machine tools equipped with rotating tool magazines and buffering tool changers. The tool order in the various magazine operation concepts is optimised with the primary objective of minimising waiting time caused by tool change and magazine rotation. Other issues such as the total tool magazine travel are also considered. Numerical experiments are conducted and an industrial case is analysed. It was found that the optimisation is most beneficial if the magazine is large, cutting times short and the tool usage frequency distribution non-uniform. Waiting time savings of 50%–70% are typical compared to the case of random tool order in the magazine. A considerable reduction of idle times and magazine travels was reached in the industrial application described. The corresponding problem in the case of unbuffered tool change was studied in the earlier Part 1 of the paper. This revised version was published online in October 2004 with a correction to the issue number.     

Lessons from the Lollipop: Biotribology,Tribocorrosion, and Irregular Surfaces

Biotribology and tribocorrosion are often not included in numerical or computational modeling efforts to predict wear because of the apparent complexity in the geometry, the variability in removal rates, and the challenge associated with mixing time-dependent removal processes such as corrosion with cyclic material removal from wear. The lollipop is an accessible bio-tribocorrosion problem that is well known but underexplored scientifically as a tribocorrosion process. Stress-assisted dissolution was found to be the dominant tribocorrosion process driving material removal in this system. A model of material removal was described and approached by lumping the intrinsically time-dependent process with a mechanically driven process into a single cyclic volumetric material removal rate. This required the collection of self-reported wear data from 58 participants that were used in conjunction with statistical analysis of actual lollipop cross-sectional information. Thousands of repeated numerical simulations of material removal and shape evolution were conducted using a simple Monte Carlo process that varied the input parameters and geometries to match the measured variability. The resulting computations were analyzed to calculate both the average number of licks required to reach the Tootsie Roll^® center of a Tootsie Roll^® pop, as well as the expected variation thereof.     

Narrow linewidth templates for nanoimprint lithography utilizing conformal deposition

Nanoimprint lithography has the potential to cost efficiently realize patterns with extremely narrow linewidth over a large area. A significant challenge to achieving this target is the fabrication of nanoimprint templates. The cost and writing time of conventional electron beam lithography for direct writing of the templates rapidly increases as the patterned area increases and the linewidth decreases. We have developed a novel process for creating narrow linewidth nanopatterns. This process is based on conformal deposition of thin films on seed nanopatterns. We have demonstrated the process by fabricating nanosized loops and lines. The linewidth of the structures can be tuned precisely, and in our experiments it could be reduced to 20?nm. The closed loop structures are interesting, since this geometry is crucially important in many leading edge research fields such as negative refractive index materials, ultrahigh density memory applications and quantum rings. The fabricated template was subsequently used as a template in soft-stamp UV nanoimprint lithography to successfully replicate the structures in UV-curable resist.