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S Welin

Publications and source records attributed to S Welin.

At least 19 recordsLinked to original sources
PubMed2005

Carbon sequestration, the precautionary approach and the responsibility of scientists.

This paper reviews problems connected to the use of the deep-sea and sub-sea geological formations for carbon sequestration. We will focus on the risks and dangers involved in using this kind of large-scale engineering approach, which is not yet fully tested, to combat global warming. We will not provide a complete discussion on the technologies involved, but concentrate on a few principal questions, such as the responsibility of environmental scientists involved in this research. We will also discuss carbon sequestration in relation to the precautionary approach. We argue that there may be a place for large-scale engineering attempts, but this should be the last rather than the first option.

Carbon↗
PubMed2001

[Organ transplantation, ethics and culture in Japan. Japanese citizens may choose between cardiac death and brain death].

The first heart transplantation in Japan was performed in 1968. However, the surgeon was prosecuted, and transplantations from cadaveric donors came to an end. A new law in 1997 offered the possibility to choose how one would be pronounced dead, and if one chose to be declared dead according to brain related criteria, then one could become a cadaveric donor, if certain conditions were fulfilled. The first donations and transplantations took place in 1999. The Japanese public has been reluctant to accept the concept of brain death. The integrity of the dead body seems to command greater respect in Japan than in Sweden, and there is a reluctance to treat body parts as exchangeable. At the same time many Japanese travel abroad to obtain organs. The act of 1997 is a very interesting way of trying to integrate a new technology in Japanese culture, and the process of obtaining informed consent from relatives relies on traditional cultural roles.

Brain Death↗
PubMed2000

Starting clinical trials of xenotransplantation--reflections on the ethics of the early phase.

What kind of patients may be recruited to early clinical trials of xenotransplantation? This is discussed under the assumption that the risk of viral infection to the public is non-negligible. Furthermore, the conditions imposed by the Helsinki declaration are analysed. The conclusion is that only patients at risk of dying and with no alternative treatment available should be recruited to xenotransplantation trials in the early phase. For some of the less dangerous cell or islet cell xenotransplantation other categories might be recruited. The risk of cell and islet cell xenotransplantation should, however, be weighted against the development of other technologies. In order to safeguard the public, the opt-out clause in the Helsinki declaration should not be fully applied. Legally binding rules on obligatory monitoring and restrictions should be imposed--before clinical trials start.

Animals↗
PubMed1991

Structure of adsorbed fibrinogen obtained by scanning force microscopy.

It is shown that scanning force microscopy (SFM), operated in the attractive mode, can be used to obtain high resolution pictures of adsorbed fibrinogen molecules on solid surfaces, without the need for staining or special microscope grids. SFM also reveals the three-dimensional structure of the adsorbed molecules. Two forms of adsorbed fibrinogen are demonstrated on hydrophobic silicone dioxide surfaces: a trinodular about 60 nm long and a globular with about a 40 nm diameter. Polymeric networks formed after storage of the surface with adsorbed fibrinogen in PBS for 11 days are also shown. The SFM-results for the trinodular structure suggest the existence of loops or peptide chains extending outside the basic structure of the fibrinogen molecule.

Fibrinogen↗
PubMed1986

Reversible and specific interaction of dehydrogenases with a coenzyme-coated surface continuously monitored with a reflectometer.

Reversible affinity binding of NAD-dependent dehydrogenase to an NAD-coated silicon surface ("NAD biochip") has been accomplished. The silicon surface, which is favorable for use with optical techniques because of its excellent reflection properties, was precoated with a polymer to prevent nonspecific and irreversible adsorption. Using a new reflectometry technique based on measurement of the polarization change of light reflected upon the biochip, continuous monitoring of the affinity binding and subsequent desorption of alcohol dehydrogenase and lactate dehydrogenase from the NAD surface were possible; allowing repeated use of the same NAD chip--an advantage when the assay was carried out in a continuous reflectometer. With a flow rate of 0.5 ml/min, response times on the order of 30 s were obtained.

Adsorption↗
PubMed1984

The interaction of proteins and cells with affinity ligands covalently coupled to silicon surfaces as monitored by ellipsometry.

Two methods for the chemical binding of biomolecules to silicon surfaces are described. The first method utilizes an alkyl silane and a nucleophilic reagent to join the biomolecule to the silicon surface; the second method involves crosslinking with glutaraldehyde in order to couple the biomolecule and albumin molecules, which have first been physically adsorbed. The course of binding to the silicon surface has been followed with the aid of ellipsometry. This optical measuring technique estimates the thicknesses of, e.g., organic layers, by measuring the polarization properties of a light beam before and after reflection at surfaces. The method by which the binding of a biomolecule to its corresponding affinity ligand on silicon wafers can be followed with this technique is reported. The systems studied are concanavalin A-Saccharomyces cerevisiae cells, immunoglobulin G-Staphylococcus aureus cells, and an NAD-analog-lactate dehydrogenase. With ellipsometry it was possible to assess how the incubation time and the concentration of the cells and the biomolecules added influenced the results. It was found that an increasing time of incubation and higher concentration resulted in a more complete coverage of the silicon wafer surfaces.

Bacteria↗