Synthetic hydrophilic polymers

Synthetic hydrophilic polymers find promising applications in pharmacology, biotechnology and chemistry. The biocompatibility, biodegradability and pharmacological activity of these polymers depend much on their hydrophilic nature. This article summarizes the recent developments in the utilization of the different classes of these hydrophilic polymers as pharmacologically active agents, for enzyme modification and as catalysts and supports for chemical reactions.     

Technical and theoretical considerations in the HLA typing of amniotic fluid cells for prenatal diagnosis and paternity testing

HLA typing of amniotic fluid cells has been used for the prenatal diagnosis of the HLA linked diseases congenital adrenal hyperplasia (21-OH-deficiency (21-OH-def) type) and complement C4 deficiency and it has also been used for the prenatal de termination of paternity. There are, however, technical difficulties in this test associated with the weak expression of some B locus antigens on amniotic fluid cells, and theoretical difficulties related to associations between particular HLA antigens and the 21-OH-def allele. Since certain HLA-B locus antigens are found in significantly increased frequencies among patients with 21-OH-def, there is a relatively high incidence of HLA-B homozygosity among the patients and over 40 percent of the parents of these patients share one or more HLA-B locus antigens. Results of some prenatal HLA typing tests may thus be difficult to interpret, and supplementary tests should be used whenever possible. HLA typing of amniotic cells is, however, the only available procedure for prenatal diagnosis of C4 deficiency and it is the best available procedure for prenatal determination of paternity. A modification of our original procedure allows HLA typing to be performed with increased numbers of HLA typing sera, and sera with optimum reactivity for amniotic fluid cells have now been selected for the definition of most of the more commonly expressed HLA antigens. Although amniotic fluid cells do not express DR antigens, amniotic fluid cells can be typed for the HLA-linked marker glyoxalase I (GLO) and this may be the informative for prenatal diagnosis in some cases.     

Climate impact from peat utilisation in Sweden

The climate impact from the useof peat for energy production in Sweden hasbeen evaluated in terms of contribution toatmospheric radiative forcing. This wasdone by attempting to answer the question`What will be the climate impact if onewould use 1 m<sup>2</sup> of mire for peatextraction during 20 years?'. Two differentmethods of after-treatment were studied:afforestation and restoration of wetland.The climate impact from a peatland –wetland scenario and a peatland –forestation – bioenergy scenario wascompared to the climate impact from coal,natural gas and forest residues.Sensitivity analyses were performed toevaluate which parameters that areimportant to take into consideration inorder to minimize the climate impact frompeat utilisation. In a `multiple generationscenario' we investigate the climate impactif 1 Mega Joule (MJ) of energy is produced every yearfor 300 years from peat compared to otherenergy sources.The main conclusions from the study are:?The accumulated radiative forcing from the peatland – forestation – bioenergy scenario over a long time perspective (300 years) is estimated to be 1.35 mJ/m²/m² extraction area assuming a medium-high forest growth rate and medium original methane emissions from the virgin mire. This is below the corresponding values for coal 3.13 mJ/ m²/ m² extraction area and natural gas, 1.71 mJ/ m²/ m² extraction area, but higher than the value for forest residues, 0.42 mJ/ m²/ m² extraction area. A `best-best-case' scenario, i.e. with high forest growth rate combined with high `avoided' methane (CH₄) emissions, will generate accumulated radiative forcing comparable to using forest residues for energy production. A `worst-worst-case' scenario, with low growth rate and low `avoided' CH₄ emissions, will generate radiative forcing somewhere in between natural gas and coal.?The accumulated radiative forcing from the peatland – wetland scenario over a 300-year perspective is estimated to be 0.73 –1.80 mJ/ m²/ m² extraction area depending on the assumed carbon (C) uptake rates for the wetland and assuming a medium-high methane emissions from a restored wetland. The corresponding values for coal is 1.88 mJ/ m²/ m² extraction area, for natural gas 1.06 mJ/ m²/ m² extraction area and for forest residues 0.10 mJ/ m²/ m² extraction area. A `best-best-case' scenario (i.e. with high carbon dioxide CO<sub>2</sub>-uptake combined with high `avoided' CH₄ emissions and low methane emissions from the restored wetland) will generate accumulated radiative forcing that decreases and reaches zero after 240 years. A `worst-worst-case' (i.e. with low CO<sub>2</sub>-uptake combined with low `avoided' CH₄ emissions and high methane emissions from the restored wetland) will generate radiative forcing higher than coal over the entire time period.?The accumulated radiative forcing in the `multiple generations' – scenarios over a 300-year perspective producing 1 MJ/year is estimated to be 0.089 mJ/ m<sup>2</sup> for the scenario `Peat forestation – bioenergy', 0.097 mJ/ m² for the scenario `Peat wetland with high CO<sub>2</sub>-uptake' and 0.140 mJ/ m<sup>2</sup> for the scenario `Peat wetland with low CO₂-uptake'. Corresponding values for coal is 0.160 mJ/ m², for natural gas 0.083 mJ/ m² and for forest residues 0.015 mJ/ m². Using a longer time perspective than 300 years will result in lower accumulated radiative forcing from the scenario `Peat wetland with high CO₂-uptake'. This is due to the negative instantaneous forcing that occurs after 200 years for each added generation.?It is important to consider CH₄ emissions from the virgin mire when choosing mires for utilization. Low original methane emissions give significantly higher total climate impact than high original emissions do.?Afforestation on areas previously used for peat extraction should be performed in a way that gives a high forest growth rate, both for the extraction area and the surrounding area. A high forest growth rate gives lower climate impact than a low forest growth rate.?There are great uncertainties related to the data used for emissions and uptake of greenhouse gases in restored wetlands. The mechanisms affecting these emissions and uptake should be studied further.