CRUW Mechanical Pulping: Sub-project 10, enzyme treatment of chips for energy reduction in TMP

In order to evaluate the possibilities of using enzymes for pre-treating softwood chips as a means of lowering the energy demand in mechanical pulping, impregnation and refining trials were performed using a set of different enzymes. The enzymes tested pectinase, xylanase and mannanase gave increased sugar release in the impregnation trials indicating that most of the sugar released occurred in the first 60 minutes and that activities thereafter seemed to level off. Refining trials using a small Wing refiner showed that for chips treated for 60 minutes with pectinase, xylanase and mannanase no energy savings to a given freeness level was observed. The property development was similar to that of reference pulps in the case of pectinase and xylanase while for chips treated with mannanase a less favourable development of the tensile index was noted. For chips treated for two hours, using xylanase or pectinase, energy savings could be observed for pectinase treated chips down to a freeness level of 200 CSF. However when refined further, the properties approached those of the reference pulp. Considering the much higher enzymatic activity reached when the initial fibre material was further disintegrated it is assumed that the possibilities for enzymes to attack desired structures of the intact fibre wall may have been too few even in the case of Impressafiner treated material

The characterization of wood and wood fibre ultrastructure using specific enzymes

Wood and wood fibre ultrastructure is of key importance for the pulp and paper making industry. In this thesis there has been a focus on development of methods for studying wood degrading enzymes. The methods have been used in different ways to render new information on wood and wood fibres. Wood degrading enzymes are chosen since they are tailor made to specifically degrade certain sub-structures in the wood bio-polymer, e.g. cellulose. In the first part an a-amino group of a carbohydrate binding module (CBM) from Phanerochaete chrysosporium cellulase Cel7D was covalently labelled with fluorescein isothiocyanate. The fluorescein labelled CBM showed specific binding only to cellulose and not to mannan and xylan. The labelled CBM was successfully used as a probe for detection of cellulose in lignocellulose material such as never dried spruce, birch wood and processed pulp fibres. Furthermore, the endoglucanase Cel5A from Trichoderma reesei and monocomponent endoglucanase from Aspergillus sp (Novozyme 476TM from Novozyme A/S) were evaluated as probes for the surface properties of soft- and hardwood chemical pulp fibres. The empirical kinetic degradation parameters correlated with the tensile index, relative bonded area and z-strength of paper. All paper properties showing a correlation with enzyme kinetic parameters were related to fibre-fibre interactions. Fluorescence labelling of the reducing end groups in pulp fibres was also used to further characterize the degradation. Finally, in vitro model studies as well as studies on intact wood samples were performed with different enzymes to characterize a fluorescent substance found in tori of water-sprinkled spruce logs. The model experiments showed that tannic acid can bind to pectin and that its presence inhibits pectinase action. Furthermore, it was shown that tannin acyl hydrolase can degrade tannic acid adsorbed to pectin. Neither pectinase nor tannase could, however, remove the discolouring substances from pit membranes in intact spruce samples. Manganese peroxidase had a minor but documented effect which, together with HCl/vanillin labelling experiments supported the conclusion that the discolouring substance corresponds to condensed tannin

Juridik och astronomi på 900-talet : Skillnader och likheter mellan två kortkvistrunhällar i nordöstra Östergötland

Obligatoriskt, icke separat poängsatt PM i den fristående kursen runkunskap</p

Juridik och astronomi på 900-talet : Skillnader och likheter mellan två kortkvistrunhällar i nordöstra Östergötland

Obligatoriskt, icke separat poängsatt PM i den fristående kursen runkunskap</p

CLEAVAGE OF SOFTWOOD KRAFT PULP FIBRES BY HCL AND CELLULASES

A new pulp fibre testing procedure called the HCl method was used to compare different spruce and pine fibres and mixtures of these fibres to calculate number of fibre cleavages in dislocations and other weak points. This method was compared with treatment of softwood kraft pulp fibres using different cellulase mixtures. The HCl method can distinguish between mill- and laboratory-made softwood kraft pulp fibres from the same wood batch. The sugar release is characterized by xylose and other hemicellulose sugars and little glucose. This is in contrast to cellulases, which despite strong fibre cleavage, did not distinguish between mill- and laboratory-made pulp fibres and released large amounts of glucose from the fibres. Hemicellulose degradation by HCl and deep penetration of the acid into the primary and secondary fibre cell walls at 80°C seems to be of major importance for the differentiation between mill and laboratory pulp fibres. Cellulases, in contrast, act mostly on the fibre surfaces, and deep penetration only takes place in amorphous regions of dislocations

Low frequencies of supernormal clutches in the Southern Dunlin and the Temminck’s Stint

Abstract Supernormal clutches are found across bird species. Such clutches often result from more than one female laying eggs in the same nest and can reflect different behaviours from parasitism to laying mistakes. Enlarged clutches are readily visible among waders due to a maximum maternal clutch size of four eggs, yet surprisingly little is known about this phenomenon. Since supernormal clutches are rare, large sample sizes are required to reliably quantify their natural frequencies. We used a large dataset to estimate the frequency of supernormal clutches in the polygamous Temminck’s Stint Calidris temminckii and the monogamous Southern Dunlin C. alpina schinzii, and examine the timing of supernormal clutches in relation to the general distribution of nest initiation dates. While supernormal clutches were very rare, they were over four times more common in the Temminck’s Stint (0.50%, n = 1594) than in the Southern Dunlin (0.11%, n = 2766). Dunlin show among the lowest frequency of supernormal clutches reported for waders. In the Temminck’s Stint, supernormal clutches were found in the middle of the season, while in the Southern Dunlin such clutches occurred in late season replacement nests. The higher rate and timing of enlarged clutches in Temminck’s Stints probably relates to the lspecies’ breeding system, which can include simultaneous courtship of multiple partners, but more work is needed to assess the relative influence of different factors. We argue that intraspecific nest parasitism is unlikely to be a primary reproductive tactic in small sandpipers