Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

[Q]: Abstract: The aim of this study was to achieve more understanding of the mass transfer characteristics of the filmadsorber haemoperfusion device. First, a structural model with mathematical description of the different diffusion steps was developed. Exact quantification appeared very difficult, resulting in insufficient fit of predicted and measured concentration curves. Moreover, the mathematics turned out simple, since the concentration courses could be described with one exponential power. Therefore, a formal model was developed, assuming linear isotherms and adsorption, proportional to the average concentration in the column. With this model predicted in-vitro inlet and outlet concentrations could be fitted to the measured data accurately. A relation between both models is given under the condition of high intraparticle mass transfer, which is allowed in case of powder adsorbents. It can be concluded that structural models do not yield predictive tools for optimization of device geometry. A formal model with two constants determining device performance enables device optimization with the help of some in-vitro experiments.
[A]: Adsorption


[Q]: Abstract: Brain topography may have its earliest expression as spatial gradients of molecules controlling the deposition of neurones and neuronal processes. In the vertebrate visual system there is evidence that the stereotyped alignment of central retinal projections relies on an initial spatially organized distribution of molecules in both the retina and its central target nuclei. We used an immunological approach to look for molecules that are so organized and produced a monoclonal antibody (JONES) which shows a pronounced dorsal to ventral gradient of binding in the rat retina throughout the period when retinal ganglion cell axons are forming topographically organized projections within the central nervous system (CNS). Binding is present throughout the radial thickness of the retinal epithelium in regions where postmitotic neurones are generated but is not associated with any consistent histological characteristic of the tissue. The antibody was shown to bind on the cell surface of freshly dissociated retinal cells, and dorsal retinal quadrants were found in vitro to have nearly twice as much antigen as ventral retinal quadrants. Initial biochemical characterization of the target epitope reveals that it is a lipid present in chloroform/methanol extracts from perinatal retina and is sensitive to neuraminidase digestion.
[A]: Animal


[Q]: Abstract: The extensive range of specificities of T-cell receptors is generated, as for immunoglobulins, by rearrangement of genetic information. Much valuable information about rearrangement processes has been inferred by comparing DNA from (monoclonal) lymphoid lines with germ-line DNA and, for B cells, from rearrangements in some Abelson murine leukaemia virus-transformed cell lines. However, because it is difficult to isolate and grow precursor populations, it has not proved possible to study rearrangements occurring in normal untransformed cells in vitro. Here we show that a single T-cell precursor colonizing an alymphoid thymus lobe in organ culture can generate multiple receptor beta-chain gene rearrangements. These observations provide unequivocal evidence for the intra-thymic diversification of the T-cell repertoire. They also offer the possibility of investigating rearrangement and its control in the clonal progeny of a single normal T-cell precursor without the perturbations involved in the use of viral transformation or the production of T-cell hybridomas.
[A]:
Animal


