Efficiency of single stage- and two stage pretreatment in biomass with different lignin content.

In current study the enzymatic glucose yields of miscanthus and wheat straw were compared after single stage- and two stage pretreatment with dilute sulfuric acid at different pretreatment severities. Glucose yields after two stage pretreatment were higher than after single stage pretreatment in miscanthus. Whereas wheat straw had higher glucose yields after single stage pretreatment. The study shows that two stage pretreatment has a negative effect on glucose yield in biomass with low not-acid-degradable lignin content and a positive one in biomass with high not-acid-degradable lignin content. The not-acid-degradable lignin fraction offers a higher degree of protection of the whole lignin structure against chemical attacks by mineral acids. More severe pretreatment conditions were needed to achieve a sufficient breakup of the lignin structure. But more severe conditions enhance resin formation, leading to lower enzyme activity and reduced carbohydrate yields.

Comparing the performance of Miscanthus x giganteus and wheat straw biomass in sulfuric acid based pretreatment.

The objective of this study was to assess and compare the suitability of Miscanthus x giganteus and wheat straw biomass in dilute acid catalyzed pretreatment. Miscanthus and wheat straw were treated in a dilute sulfuric acid/steam explosion pretreatment. As a result of combining dilute sulfuric acid- and steam explosion pretreatment the hemicellulose hydrolysis yields (96% in wheat straw and 90% in miscanthus) in both substrates were higher than reported in literature. The combined severity factor (=CSF) for optimal hemicellulose hydrolysis was 1.9 and 1.5 in for miscanthus and wheat straw respectively. Because of the higher CSF value more furfural, furfuryl alcohol, 5-hydroxymethylfurfural and acetic acid was formed in miscanthus than in wheat straw pretreatment.

Comparative responses to water stress in stay-green, rapid- and slow senescing genotypes of the biomass crop, Miscanthus.

• Although hybrids of the perennial rhizomatous grass Miscanthus give high yields under irrigation, their use as a biomass crop in many locations is limited by inadequate water availability. Here, the effects of reduced water availability on growth are reported for three Miscanthus genotypes with differing responses to drought. • In a controlled environment experiment during a drought treatment M. sinensis hybrid (Sin-H6) had no detectable photosynthesis and negligible leaf conductance, whereas M. × giganteus (Gig-3) continued to photosynthesize and transpire but it shed leaf area through senescence. A M. sacchariflorus line (Sac-5) was generally intermediate in its response. Measurements on 3-y-old stands of Gig-3 and Sin-H6 in the field during a short summer drought in August 1999 confirmed the controlled environment observations. • Stay-green characteristics in Sin-H6 appeared to rely on tight control of transpiration through lowered leaf conductance, although the highest leaf ABA concentrations were not found in this genotype. • Stay-green genotypes, such as Sin-H6, are likely to be important for further breeding of Miscanthus because they appear to make the most effective use of available water.

Parenteral nutrition with a "breast milk adapted" solution of amino acids in infants and children after abdominal surgery.

Plasma amino acid levels as well as urinary and plasma concentrations of nitrogen were determined in 24 infants and 12 children on five consecutive days after major abdominal surgery. Parenteral nutrition was carried out by means of two different amino acid solutions. One formula (PE) was based on the amino acid composition of potato-egg protein, the other (BM) on that of human breast milk. Control subjects received glucose only. The controls showed decreased plasma levels of most amino acids as well as negative nitrogen balances. In contrast, in the patients treated with amino acids the plasma concentrations of most amino acids were found in the normal range. In the infants elevated plasma amino acid levels were found more often in the BM-group than in the PE-group. Among the children, however, the PE-group showed an elevation in the plasma levels of amino acids more frequently than the BM-group. There is no significant difference in the positive nitrogen balance between the BM-groups and the PE-groups. Therefore, it can be concluded that the use of BM has no clear advantage over that of PE.