Application of Laplace transforms for the solution of transient mass- and heat-transfer problems in flow systems

A fast numerical technique for the solution of partial differential equations describing timedependent two- or three-dimensional transport phenomena is developed. It is based on transforming the original time-domain equations into the Laplace domain where numerical integration is performed and by subsequent numerical inverse transformation the final solution can be obtained. The computation time is thus reduced by more than one order of magnitude in comparison with the conventional finite-difference techniques. The effectiveness of the proposed technique is demonstrated by illustrative examples

Molecular Gastronomy: A Food Fad or an Interface for Science-based Cooking?

A review is given over the field of molecular gastronomy and its relation to science and cooking. We begin with a brief history of the field of molecular gastronomy, the definition of the term itself, and the current controversy surrounding this term. We then highlight the distinction between molecular gastronomy and science-based cooking, and we discuss both the similarities and the distinctions between science and cooking. In particular, we highlight the fact that the kitchen serves as an ideal place to foster interactions between scientists and chefs that lead to benefits for the general public in the form of novel and high-quality foods. On the one hand, it can facilitate the implementation of new ideas and recipes in restaurants. On the other hand, it challenges scientists to apply their fundamental scientific understanding to the complexities of cooking, and it challenges them to expand the scientific understanding of many chemical and physical mechanisms beyond the common mass-produced food products. In addition, molecular gastronomy forms an ideal base to educate the general public about the basic principles of science and cooking and how they can be utilized to improve the awareness of the role of food and nutrition for the quality of life

Delivery of Functionality in Complex Food Systems: Physically Inspired Approaches from Nanoscale to Microscale, Wageningen 18-21 October 2009

The Wageningen Delivery of Functionality symposium covered all aspects involved with food structural design to arrive at high-quality foods which meet demanding customer expectations and regulatory requirements. The symposium integrated aspects from the structural organization of foods at molecular and supramolecular scales to dedicated techniques required to describe and visualize such structures, the gastro-intestinal events and how to model these in a laboratory setting, and finally the impact those food structures and ingredients have on the consumer’s physiology and on the human perception. As an interdisciplinary platform, bringing together more than 160 researchers from academia and industry, the symposium meanwhile fulfills an important role in the food science communit

A knowledge-based system for the automatic chronopotentiometric elucidation of electrode reaction mechanisms

A knowledge-based system for the elucidation of electrode reaction mechanisms based on chronopotentiometric experiments is described. The system runs the diagnostic experiments and uses the results in the reasoning process. New mechanistic knowledge can be added directly to its knowledge base in the form of production rules. The system is fully modular and its domain- specific modules can easily be changed for application to other electrochemical techniques. Correct operation of the system is demonstrated with the familiar reduction mechanisms of cadmium (II), zinc (II), cystamine and cinnamaldehyde

Mathematical modelling of a flow-injection system with a membrane separation module

A mathematical model for a flow-injection system with a membrane separation module based on the axially dispersed plug flow model was developed. It takes into account the geometrical dimensions and dispersion properties of the main sections of the manifold, the mass transfer in the channels of the separation module and the characteristics of the membrane (thickness and diffusion coefficient within it). The model was solved analytically in the Laplace domain. The inverse transformation was found to give satisfactory results for reactor Peclet numbers less than 120. Otherwise a numerical solution based on the implicit alternating-direction finite difference method was preferred. The adequacy of the model was confirmed experimentally on a flow-injection manifold with a parallel-plate dialysis module. The unknown flow and membrane parameters were determined by curve fitting. The membrane parameters were determined also by steady-state measurements. Fairly good agreement between the dynamic and steady-state results and with results given in the literature was observed, which, together with other experimental results, supported the validity of the model and showed that it can be used successfully for the mathematical description and optimization of flow-injection systems with membrane separation modules. In this connection, the influence of the reactor parameters and the sample volume on the performance of such a system were investigated and conclusions for improving its sensitivity and sample throughput were drawn. Other possible applications of the model are in membrane technology for characterizing of various membranes and in process engineering for investigating the mass transfer in different dialysers

Determination of water in organic solvents by flow-injection analysis with Karl Fischer reagent and a biamperometric detection system

A flow-injection system with a biamperometric flow-through detector provided with two platinum plate electrodes was tested for the determination of water with a two-component pyridine-free Karl Fischer reagent. The response was shown to be linear in the concentration range 0.03–0.11% water in methanol, ethanol or 2-propanol, with methanol as the carrier solvent. The maximum sampling frequency was about 150 samples per hr. It appeared to be possible to introduce a membrane separation step, thus allowing for the determination of water in fouled process streams. To avoid direct contact between the Karl Fischer solution and the pumping tubes, and thus extend the lifetime of the tubes, an indirect delivery system, based on replacement of the solution by pumped silicone oil, was also applied

Measuring thermal conductivity in extreme conditions: sub-Kelvin temperatures and high (27 T) magnetic fields

We present a one-heater-two-thermometer set-up for measuring thermal conductivity and electric resistivity of a bulk sample at low temperatures down to 0.1 K and in magnetic fields up to 27 Tesla. The design overcomes the difficulties emerging in the context of large water-cooled resistive magnets.Comment: 4 pages including 4 figure

Percutaneous Treatment of Peripheral Vascular Malformations

Vascular malformations arise from errors in the morphological processes that shape the embryonic vascular system during fetal development. These developmental errors result in abnormal clusters of blood vessels. Although these lesions are present at birth, they might not become visible until weeks or even years after birth. Typically, the lesions grow in proportion to the growth of the child. A vascular malformation will not disappear without treatment. Vascular malformations occur in 1.5% of the population and the male to female ratio is 1:1. The symptoms can vary, and they include cosmetic complaints, tissue ulceration, pain, swelling, and functional limitations. In some patients the symptoms are mild, in which case conservative measures might be sufficient. In contrast, patients with severe symptoms might require more invasive treatment. Surgery, interventional radiology, laser therapy or a combination of techniques are used in the treatment of vascular malformations. However, as a result of their rarity, the correct diagnosis and treatment of vascular malformations is difficult, because most physicians do not see these problems often enough to become knowledgeable about their management. For the purpose of this review we performed a literature search to outline the classification, pathogenesis and histological findings, clinical presentation, and treatment of peripheral vascular malformations. We used the PubMed and MeSH databases for the literature search. The following MeSH terms were used: vascular malformations, haemangioma, and arteriovenous malformations, with the subheadings: classification, aetiology, genetics, surgery, and therapy. A specific time interval, 1960 to 2010, was used. In addition, we included in the search the names of groups of investigators who are known to be associated with the different topics and reference lists from other review articles on the same topics. We limited our search to only peripheral vascular malformations and excluded supratentorial and spinal vascular malformations, as well as those of the abdominal and thoracic organs. We focused on publications that described the classification, pathogenesis and genetics of the condition, and non-interventional radiology treatments. This identified a total of 110 publications. The use of an additional database did not reveal any other publications