| 1. |
- Aldaeus, Fredrik, et al.
(författare)
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Characterization of pulp with high enzymatic hydrolyzability
- 2014
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Ingår i: 13th European Workshop on Lignocellulosics and Pulp (EWLP 2014) book of abstracts.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Conversion of biomass to biofuels is currently an area that attracts large interest, and lignocellulosic biomass offers the abundance and environmental attributes that can potentially support large-scale biofuel production as an alternative to petroleum-based transportation fuel.In a recent project, Innventia has developed wood based pulps optimized for conversion to biofuels. These novel pulps were produced to target a high level of enzymatic hydrolyzability. To assess the hydrolyzability of these pulps, a laboratory protocol has been established usingan enzyme mixture containing Celluclast 1.5L and Novozyme 188 with an activity of 10 FPU/g pulp (Andersen 2007). Results obtained using this protocol are assumed to be relevant for industrial conditions. In addition to assessment of the produced pulps, the results havebeen compared to commercial cellulose substrates and pulps of a variety of grades.Furthermore, supramolecular properties – specific surface area and average pore size – were determined by an in-house method utilizing solid state nuclear magnetic resonance (Larsson et al. 2013). Kappa numbers, limiting viscosities, ISO-brightness and carbohydrate compositions were determined using standard methods. Molecular mass distributions of cellulose tricarbanilates were determined by size exclusion chromatography with tetrahydrofuran mobile phase (Drechsler et al. 2000).The presentation will discuss the influence of chemical, macromolecular and supramolecular properties of commercial and novel pulp grades on the enzymatic hydrolyzability. Theprotocol used to assess of enzymatic hydrolyzability will be proposed as a benchmark test.
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| 2. |
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| 3. |
- Aldaeus, Fredrik, et al.
(författare)
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The supramolecular structure of cellulose-rich wood and wheat straw pulps can be a determinative factor for enzymatic hydrolysability
- 2016
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Ingår i: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives. ; , s. 39-39
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Conversion of biomass to biofuels and other products is a research area that is currently attracting a great amount of interest, particularly because such production may be envisaged as a key part of any bio-based economy. Lignocellulosic biomass is abundant and sustainable, and can therefore potentially support large-scale production of biofuel as an alternative to petroleum-based fuel.The enzymatic hydrolysability of three industrial pulps, five lab made pulps, and one microcrystalline cellulose powder was assessed using commercial cellulolytic enzymes. To gain insight into the factors that influence the hydrolysability, a thorough characterization of the samples was done, including their chemical properties (cellulose content, hemicellulose content, lignin content, and kappa number), their macromolecular properties (peak molar mass, number-average molar mass, weight-average molar mass, polydispersity, and limiting viscosity) and their supramolecular properties (fibre saturation point, specific surface area, average pore size, and crystallinity). The hydrolysability was assessed by determination of initial conversion rate and final conversion yield, with conversion yield defined as the amount of glucose in solution per unit of glucose in the substrate. Multivariate data analysis revealed that for the investigated samples the conversion of cellulose to glucose was mainly dependent on the supramolecular properties, such as specific surface area and average pore size. The molar mass distribution, the crystallinity, and the lignin content of the pulps had no significant effect on the hydrolysability of the investigated samples.In addition, experiments were carried out aiming at identifying suitable conditions for pre-treatment of wheat straw, for the purpose of making cellulose rich pulps with improved enzymatic reactivity. Two sets of conditions for pre-treatment of wheat straw were identified; a combination of low temperature alkaline washing and acid pre-hydrolysis, or high temperature acid pre-hydrolysis. Both bleached wheat straw pulps showed similar enzymatic reactivity. However, the enzymatic reactivity of both bleached wheat straw pulps was found to be significantly less than what has been achieved for wood pulps. A probable explanation for the low enzymatic reactivity of the bleached wheat straw pulp can be the small pore size, limiting the access for enzymes to the cellulose surfaces in the fibre wall interior.Text, figures and tables in an extended abstract (< 4 pages with title and references).
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| 4. |
- Alm, Hajer Kamal, et al.
(författare)
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Effect of excess dispersant on surface properties and liquid interactions on calcium carbonate containing coatings
- 2010
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 25:1, s. 82-92
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to identify what effects excess amount of sodium polyacrylate, a commonly used dispersant, has on the coating properties and the interaction between ink and the paper coating in offset printing. Since polyacrylate strongly interacts with calcium ions, soluble calcium salt was added to some coating colours to illustrate the impact of charge neutralization by calcium ions. It was found that the coating structure was only slightly affected by the extra addition of polyacrylate, showing some weak flocculation, whereas the surface chemistry was strongly influenced. The coatings became more polar and interacted more strongly with water. This resulted in slower ink setting and reduced ink-paper coating adhesion, especially in the presence of applied water/dampening solution, which are identified as contributory factors in ink piling and print mottle.
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| 5. |
- Antonsson, Stefan, et al.
(författare)
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Applying a novel cooking technique to produce high kappa number pulps : the effects on physical properties
- 2009
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 24:4, s. 415-420
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Tidskriftsartikel (refereegranskat)abstract
- A recently developed kraft cooking technique, with a longer impregnation time at lower temperatures to facilitate diffusion over consumption of active cooking chemicals, makes it possible to produce kraftliner pulp without inline refining. This technique was applied to prepare two pulps with different lignin contents, which were compared with two industrial pulps from conventional kraft cooks in order to evaluate the physical properties of the pulps. It was demonstrated that pulps with lower lignin content can increase tensile stiffness, decrease hygroexpansion, and decrease the mechano-sorptive creep of handsheets. However, no difference in SCT and tensile energy absorption values due to different lignin contents was observed. It was further demonstrated that pulps made with Extended Impregnation Cooking (EIC) results in straighter pulp fibres with higher cellulose content. These pulps tended to have lower mechano-sorptive creep than conventional pulps. A higher brightness of the pulp sheets can also be obtained by choosing a higher alkali profile.
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| 6. |
- Antonsson, Stefan, et al.
(författare)
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The relationship between hygroexpansion, tensile stiffness, and mechano–sorptive creep in bleached hardwood kraft pulps
- 2010
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Ingår i: Appita journal. - 1038-6807. ; 63:1, s. 231-
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Tidskriftsartikel (refereegranskat)abstract
- Hygroexpansion coefficient and tensile stiffness are important parameters in many paper applications. This study compares several bleached industrial hardwood kraft pulps, comprising five eucalypt pulps from South America, Europe, and Africa as well as an acacia pulp from Asia and a birch pulp from Scandinavia. Refined and unrefined pulps are compared. The results indicate significant differences in hygroexpansion but smaller differences in tensile stiffness index at comparable densities. No single factor offering a reasonable explanation of these differences in hygroexpansion coefficient, such as carbohydrate composition, fibre dimensions, or fibre form, was found. However, correlation between hygroexpansion coefficient and the mechano-sorptive creep stiffness was observed. We suggest that the hygroexpansion coefficient at a given tensile stiffness level can be used to rank pulps in terms of their mechano-sorptive creep properties.
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| 7. |
- Bäck, Lena, 1962-
(författare)
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Confidence in Midwifery : Midwifery students and midwives’ perspectives
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A confident midwife has an impact on a pregnant woman’s clinical outcome and birth experience. Knowledge acquisition, competence, and confidence develops over a lifetime and is of great importance in developing and forming personal skills and allowing the personal traits to grow and mature. Previous international studies have shown that midwifery students do not feel confident in many areas in which they are supposed to practice independently. The aim of this thesis was to investigate confidence levels in basic midwifery skills in Swedish midwifery students in their final semester just before entering the midwifery profession. An additional aim was to describe clinical midwives’ reflections about learning and what factors that developes professional competence, and confidence.Study I was a cross-sectional survey with Swedish midwifery students (n=238). They assessed their own confidence in all competencies that a midwife should have and could practice independently. The results of study I confirmed that Swedish midwifery students feel confident in dealing with the most common procedures during normal pregnancy, childbirth, and postpartum and newborn care. However, they do not feel fully confident in cases in which there are deviations from the normal procedures and obstetric emergencies. When comparing groups of midwifery students, the younger group of midwifery students felt more confident in general compared to the older group. Students at a university with a medical faculty were also more confident than the students at a university without a medical faculty.In study II, focus group discussions were held with 14 midwives emphasizing the way in which midwives reflect on learning and the development of competence and confidence. Content analysis was used to analyze the focus group discussions. Four categories were identified as a result of study II: 1.) feelings of professional safety evolve over time; 2.) personal qualities affect professional development; 3.) methods for knowledge and competence expansion; and 4.) competence as developing and demanding. The conclusion of this thesis is that more practical and clinical training during education is desirable. Midwifery students need to have access and the opportunity to practice obstetrical emergencies within a team of obstetricians and pediatricians. Learning takes time, and one improvement is to extend midwifery education to include and increase in clinical training. This would strengthen the students theoretical, scientific, and clinical confidence. Clinical midwives claim that it takes time to feel confident and that there is a need to develop professionalism.
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| 8. |
- Bäck, Lena, 1962-, et al.
(författare)
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Professional confidence among Swedish final year midwifery students - A cross-sectional study
- 2017
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Ingår i: Sexual & Reproductive HealthCare. - : ELSEVIER IRELAND LTD. - 1877-5756 .- 1877-5764. ; 14, s. 69-78
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Previous international studies have shown that midwifery students do not feel confident in many areas where they are supposed to practice independently. The knowledge about Swedish midwifery students' confidence is fairly under investigated. The purpose of the present study was to explore final years' midwifery students' professional confidence in basic midwifery skills according to ICM competencies and associated factors.Methods: A cross-sectional survey where all midwifery programs in Sweden were invited to participate. Data was collected by a questionnaire that measured midwifery students self-reported assessment of confidence against four selected domains of ICM competencies; antenatal, intrapartum, postpartum and new-born care.Result: The main findings of this study showed that Swedish midwifery students were confident in managing normal pregnancy, labour and birth. Midwifery students at a school with a medical faculty were more confident in handling obstetric emergency situations. Some background variables were also associated with confidence.Conclusion: This study highlighted some midwifery skills that needs further training and reflection. More training and developing confidence in complicated and emergency situations are needed. There seem to be a need of midwifery education reforms if we believe that high levels of confidence at the time of graduation is equal to competent and skilled midwives in the future.
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| 9. |
- Gospic, Katarina, et al.
(författare)
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Altruism costs-the cheap signal from amygdala
- 2014
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Ingår i: Social Cognitive & Affective Neuroscience. - : Oxford University Press (OUP). - 1749-5016 .- 1749-5024. ; 9:9, s. 1325-1332
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Tidskriftsartikel (refereegranskat)abstract
- When people state their willingness to pay for something, the amount usually differs from the behavior in a real purchase situation. The discrepancy between a hypothetical answer and the real act is called hypothetical bias. We investigated neural processes of hypothetical bias regarding monetary donations to public goods using fMRI with the hypothesis that amygdala codes for real costs. Real decisions activated amygdala more than hypothetical decisions. This was observed for both accepted and rejected proposals. The more the subjects accepted real donation proposals the greater was the activity in rostral anterior cingulate cortex-a region known to control amygdala but also neural processing of the cost-benefit difference. The presentation of a charitable donation goal evoked an insula activity that predicted the later decision to donate. In conclusion, we have identified the neural mechanisms underlying real donation behavior, compatible with theories on hypothetical bias. Our findings imply that the emotional system has an important role in real decision making as it signals what kind of immediate cost and reward an outcome is associated with.
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| 10. |
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| 11. |
- Karlström, Katarina, 1963-, et al.
(författare)
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Extended Impregnation Cooking of Norway Spruce : Effects on Pulping Uniformity and Pulp Strength Properties
- 2009
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Extended impregnation kraft cooking is a demonstrated improvement of the kraft pulping process and offers a way to use softwood more efficiently. We demonstrate the possibility of producing Norway spruce (Picea abies) kraft pulp using a new cooking concept, producing a pulp that can be defibrated without inline refining at kappa numbers of approximately 90. The cooking concept uses the differences in reaction rate between the diffusion and consumption of hydroxide ions in the prolonged impregnation step. Lowering the impregnation temperature will favour the diffusion of cooking chemicals over neutralization reactions, thereby improving chemical distribution throughout the chips. Impregnation conditions in combination with cooking temperatures lower than those of conventional kraft pulping are demonstrated to produce pulp with a narrower kappa number distribution and comparable strength properties at a considerably higher yield.
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| 12. |
- Karlström, Katarina, 1963-
(författare)
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Extended impregnation kraft cooking of softwood : Effects on reject, yield, pulping uniformity, and physical properties
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Converting wood into paper is a complex process involving many different stages, one of which is pulping. Pulping involves liberating the wood fibres from each other, which can be done either chemically or mechanically. This thesis focuses on the most common chemical pulping method, the kraft cooking process, and especially on a recently developed improvement of the impregnation phase, which is the first part of a kraft cook. Extended impregnation kraft cooking (EIC) technique is demonstrated to be an improvement of the kraft pulping process and provides a way to utilize softwood to a higher degree, at higher pulp yield. We demonstrate that it is possible to produce softwood (Picea abies) kraft pulp using a new cooking technique, resulting in a pulp that can be defibrated without inline refining at as high lignin content as 8% on wood, measured as kappa numbers above 90. Lignin is the wood constituent that holds the wood fibres together in the wood matrix. The new cooking technique uses the differences in reaction rate between the diffusion and consumption of hydroxide ions; it is used to ensure a homogenous impregnation of wood chips at lower impregnation temperatures and longer impregnation times than are generally used in the industry. The applied cooking temperatures are also substantially lower than those used in conventional kraft pulping systems, promoting uniform delignification. This results in a narrower kappa number distribution than in lab-cooked conventional kraft pulp. High-kappa-number pulps were investigated for pulp sheet properties such as tensile strength, tensile stiffness, and compression strength. It was demonstrated that an EIC pulp of kappa number 95 has strength properties comparable to those of a conventional pulp of kappa number 82. Comparing the effects of starch multilayers on conventional and EIC pulps reveals similar effects. The use of the starch multilayer treatment increased the tensile index and decreased the tensile stiffness and short-span compression test (SCT) indices. The EIC technique has also been used to produce a series of bleachable-grade pulps. The results indicate the possibility of increasing the lignin content of the pulp entering the oxygen delignification stage, since the reject content of gently defibered pulp is lower than 0.1% at kappa number 49. In this thesis, we recommend that wood chips be impregnated for 2 h at 110 °C to neutralize acidic compounds in the wood and impregnate the chips with cooking chemicals, and that the ensuing cook be performed at 135–140 °C, depending on the target kappa number. We also recommend increasing the available amounts of cooking chemicals in the impregnation stage by using a higher liquor-to-wood ratio and keeping the alkali profile fairly high in the ensuing cook. This concept will reduce the amount of reject material, increase the pulping uniformity, and increase the selectivity towards lignin degradation in the kraft cook.
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| 13. |
- Karlström, Katarina, et al.
(författare)
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Sulphur-free cooking for value added cellulose
- 2014
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Ingår i: Cellulose Chemistry and Technology. - 0576-9787. ; 48:9-10, s. 781-786
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Tidskriftsartikel (refereegranskat)abstract
- To study sulphur- and chlorine-free processes to produce pulps for triacetylation and preparation of films for LCD screen application was one of the aims in the EU project AFORE. It was shown possible to produce pulp suitable for triacetylation from Eucalyptus globulus chips with pre-hydrolysis soda cooking and a single oxygen delignification step. Pre-hydrolysis with water at elevated temperatures extracts wood components, mainly hemicelluloses and the wood matrix is opened to facilitate alkaline pulping. After a severe pre-hydrolysis extracting some 25% of the wood raw material, a subsequent soda cook reduces the lignin content to about 1%. The oxygen delignification step produces a pulp with low lignin content, kappa no 1.4, and low hemicelluloses content, < 2 wt% xylose. The resulting cellulose had high molar mass and produced highly transparent triacetate solutions. It was also possible to produce a transparent cellulose triacetate film by solution casting with good physical properties without using plasticizer. The process also results in a sulphur-free black-liquor suitable for lignin separation by the LignoBoost process. The resulting lignin is of high purity with low hemicelluloses content.
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| 14. |
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| 15. |
- Larsson, Per Tomas, et al.
(författare)
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Characterization of cellulose supramolecular structure using solid-state NMR
- 2014
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Ingår i: Analysdagarna book of abstracts.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cellulose I isolated from wood in the form of cellulose-rich fibres, i.e. as a pulp, is a widely used raw material that holds a potential for further and more versatile use. Due to its abundance cellulose can be a benign replacement for many materials used in everydaycommodities.Isolated cellulose I is associated with a complex supramolecular structure (in the nanometresdimensional range), and in the case of cellulose-richfibres it is also associated with a complex fibre wall morphology (typical wood fibres are millimetres long and tenths of micrometres wide).The main advantage of using cellulose-rich fibres is an existence of a worldwide industry which has the processing equipment and the know-how necessary for efficient handling and processing of wood-based pulps.Utilization of cellulose I is dependent on the reactivity of the cellulose substrate, here the term reactivity is used in a broad sense. Enzymatic conversion of cellulose-rich fibres to sugars or the dissolution of cellulose for textile fibre manufacture is two examples where different aspects of the cellulosereactivity are important for efficient processing.Several methods for characterizing various aspects of cellulose are available. The degree of polymerization and the degree of cellulose crystallinity are two examples. In the case of cellulose-rich fibres its carbohydrate composition can be of importance. Traditionally lessattention has been paid to the supramolecular characteristics of cellulose although they are in a dimensional range that could exert an influence on the chemistry used.The present work deals with the characterization of the supramolecular properties of cellulose and cellulose-rich fibres and illustrates some examples where the supramolecular structure of the cellulose is a controlling factor for its reactivity. Most of the presented work is based on CP/MAS 13 C-NMR measurements. Using this technique it has been shown that robust measurements of cellulose nanostructures such aslateral fibril dimensions and lateral fibril aggregate dimensions can be obtained and how subsequently the specific surface area of the cellulose in a water-swollen state can be estimated. Moreover, by combining NMR resultswith measurements of the amount of water located inside a water-swollen fibre wall, estimates of the average fibre wall pore size can be obtained. Such results have beenrelated to data from enzymatic hydrolysis of cellulose-richfibres to illustrate the influence of supramolecular structure on enzymatic reactivity.
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| 16. |
- Peciulyte, Ausra, 1986, et al.
(författare)
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Cellulolytic enzyme interaction with lignocellulose. Insight to factors limiting enzymatic hydrolysis
- 2013
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Ingår i: Gordon Conference: Cellulosomes, Cellulases & Other Carbohydrate Modifying Enzymes internal database.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Liberation of fermentable soluble sugars from lignocellulosic biomass during the course of enzymatic hydrolysis is the major obstacle to large-scale implementation of biorefineries due to high cost of enzymes. Enzymatic hydrolysis of lignocellulosic biomass is often incomplete and, therefore, it is of great importance to understand the limitations of the process. Among the limitations of enzymatic hydrolysis, structural properties of lignocellulose have an effect of enzymatic hydrolysis efficiency. Currently, there is a lack of direct methods for visualization and quantification of spatial polymer distribution in lignocellulosic biomass and monitoring of interactions between cellulose degrading enzymes and the substrate. The focus of the work was (i) structural characterization of lignocellulose during the course of hydrolysis and (ii) to provide a more detailed understanding of cellulolytic enzyme interaction with lignocellulose. The overall aim was to understand the limitations in enzymatic hydrolysis of lignocellulosic biomass.Enzymatic hydrolysis was studied on industrial-like lignocellulosic and cellulosic substrates, resulting from alkaline pulping and steam explosion of spruce. Enzymatic hydrolysis of lignocellulosic substrates was compared to enzymatic hydrolysis of model cellulosic substrates. Enzymatic hydrolysis of the substrates was performed with commercial enzyme mixture Celluclast 1.5 L and also with designed enzyme mixtures, consisting of mono-component enzymes. The structural properties of the substrates during an incrementing time of hydrolysis were analyzed by solid-state Nuclear Magnetic Resonance (NMR) spectroscopy, Coherent Anti-Strokes Raman Scattering (CARS) and Second Harmonic Generation (SHG) microscopy. Hydrolysis products were verified by High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD). Dynamics of the hydrolysis was analyzed by Quartz Crystal Microbalance with Dissipation (QCM-D) technique.
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| 17. |
- Peciulyte, Ausra, 1986, et al.
(författare)
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Challenges in cellulolytic enzyme production by filamentous fungus Trichoderma reesei Rut C-30 on cellulosic materials
- 2013
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Ingår i: 35th Symposium on Biotechnology for Fuels and Chemicals abstract book.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The industrial cellulase production is dominated by the filamentous fungus Trichoderma reesei. The switch of the carbon sources from lactose, traditionally used for industrial cellulase production, to lignocellulose, such as residual plant materials, could potentially reduce the cost of the enzyme production process. However, enzyme productivities are significantly lower on cellulose than on lactose. We studied the enzyme production by T. reesei strain Rut C-30 on model and industrial cellulosic substrates. Our aim was to understand how different raw materials influence the levels and profiles of the proteins produced. Enzyme production by T. reesei Rut C-30 was studied in submerged cultivations on commercial cellulose Avicel and industrial-like cellulosic substrates from softwood, which mainly consist of cellulose, but also contain residual hemicellulose, lignin and some inhibitors. These substrates were produced by alkaline pulping, used in pulp and paper industry. In order to evaluate hydrolysis and consumption of the substrates by fungal enzymes, the substrates were characterized by HPAEC-PAD and solid-state NMR. Lignin was analyzed by gravimetric method. Protein profile was examined by isobaric tag for relative and absolute quantification (iTRAQ). Inhibitors, soluble sugars and lignin degradation products did not have impact on the growth ability of T. reesei Rut C-30, but the fungal morphology was severely influenced during the growth on industrial-like substrates. Industrial-like substrates yielded less enzymes and enzyme adsorption may be one important factor influencing protein yields in the cultivations. Fungal growth on different substrates resulted in distinct protein profiles.
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| 18. |
- Peciulyte, Ausra, 1986, et al.
(författare)
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Enzymatic hydrolysis of cellulose: linking hydrolyzability with cellulose characteristics
- 2014
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Ingår i: Science and Technology Day book of abstracts.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Liberation of fermentable soluble sugars from cellulosic biomass during the course of enzymatic hydrolysis is the major obstacle to large-scale implementation of biorefineries due to high cost of enzymes. Enzymatic hydrolysis of cellulosic biomass is often incomplete and, therefore, it is of great importance to understand the limitations of the process. Among the limitations of enzymatic hydrolysis, structural properties of cellulose have an effect of enzymatic hydrolysis efficiency. The focus of the present work was structural characterization of cellulose during the course of hydrolysis which indirectly gives information about the interaction between the enzymes and the substrate. The overall aim was to understand the limitations in enzymatic hydrolysis of cellulosic biomass.Enzymatic hydrolysis was studied on industrial-like cellulosic substrates, resulting from alkaline pulping of softwood. Enzymatic hydrolysis of cellulosic substrates was compared to enzymatic hydrolysis of model cellulosic substrates. Enzymatic hydrolysis of the substrates was performed with commercial enzyme mixture Celluclast 1.5 L. The structural properties of the substrates during an incrementing time of hydrolysis were analyzed by solid-state Nuclear Magnetic Resonance (NMR) spectroscopy, Coherent Anti-Strokes Raman Scattering (CARS) and Second Harmonic Generation (SHG) microscopy. Hydrolysis products were verified by High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD).
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| 19. |
- Peciulyte, Ausra, 1986, et al.
(författare)
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Impact of the supramolecular structure of cellulose on the efficiency of enzymatic hydrolysis
- 2015
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Background: The efficiency of enzymatic hydrolysis is reduced by the structural properties of cellulose. Although efforts have been made to explain the mechanism of enzymatic hydrolysis of cellulose by considering the interaction of cellulolytic enzymes with cellulose or the changes in the structure of cellulose during enzymatic hydrolysis, the process of cellulose hydrolysis is not yet fully understood. We have analysed the characteristics of the complex supramolecular structure of cellulose on the nanometre scale in terms of the spatial distribution of fibrils and fibril aggregates, the accessible surface area and the crystallinity during enzymatic hydrolysis. Influence of the porosity of the substrates and the hydrolysability was also investigated. All cellulosic substrates used in this study contained more than 96% cellulose. Results: Conversion yields of six cellulosic substrates were as follows, in descending order: nano-crystalline cellulose produced from never-dried soda pulp (NCC-OPHS-ND) > never-dried soda pulp (OPHS-ND) > dried soda pulp (OPHS-D) > Avicel > cotton treated with sodium hydroxide (cotton + NaOH) > cotton. Conclusions: No significant correlations were observed between the yield of conversion and supramolecular characteristics, such as specific surface area (SSA) and lateral fibril dimensions (LFD). A strong correlation was found between the average pore size of the starting material and the enzymatic conversion yield. The degree of crystallinity was maintained during enzymatic hydrolysis of the cellulosic substrates, contradicting previous explanations of the increasing crystallinity of cellulose during enzymatic hydrolysis. Both acid and enzymatic hydrolysis can increase the LFD, but no plausible mechanisms could be identified. The sample with the highest initial degree of crystallinity, NCC-OPHS-ND, exhibited the highest conversion yield, but this was not accompanied by any change in LFD, indicating that the hydrolysis mechanism is not based on lateral erosion.
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| 20. |
- Peciulyte, Ausra, 1986, et al.
(författare)
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Morphology and enzyme production of Trichoderma reesei Rut C-30 are affected by the physical and structural characteristics of cellulosic substrates
- 2014
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Ingår i: Fungal Genetics and Biology. - : Elsevier BV. - 1087-1845 .- 1096-0937. ; 72, s. 64-72
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Tidskriftsartikel (refereegranskat)abstract
- The industrial production of cellulolytic enzymes is dominated by the filamentous fungus Trichoderma reesei (anamorph of Hypocrea jecorina). In order to develop optimal enzymatic cocktail, it is of importance to understand the natural regulation of the enzyme profile as response to the growth substrate. The influence of the complexity of cellulose on enzyme production by the microorganisms is not understood. In the present study we attempted to understand how different physical and structural properties of cellulose-rich substrates affected the levels and profiles of extracellular enzymes produced by T. reesei. Enzyme production by T. reesei Rut C-30 was studied in submerged cultures on five different cellulose-rich substrates, namely, commercial cellulose Avicel (R) and industrial-like cellulosic pulp substrates which consist mainly of cellulose, but also contain residual hemicellulose and lignin. In order to evaluate the hydrolysis of the substrates by the fungal enzymes, the spatial polymer distributions were characterised by cross-polarisation magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS C-13-NMR) in combination with spectral fitting. Proteins in culture supernatants at early and late stages of enzyme production were labeled by Tandem Mass Tags (TMT) and protein profiles were analysed by liquid chromatography-tandem mass spectrometry. The data have been deposited to the ProteomeXchange with identifier PXD001304. In total 124 proteins were identified and quantified in the culture supernatants, including cellulases, hemicellulases, other glycoside hydrolases, lignin-degrading enzymes, auxiliary activity 9 (AA9) family (formerly GH61), supporting activities of proteins and enzymes acting on cellulose, proteases, intracellular proteins and several hypothetical proteins. Surprisingly, substantial differences in the enzyme profiles were found even though there were minor differences in the chemical composition between the cellulose-rich substrates.
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| 21. |
- Peciulyte, Ausra, 1986, et al.
(författare)
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Nonlinear microscopy and CP/MAS 13C-NMR as tools for studying structural changes of cellulosic substrates during enzymatic hydrolysis
- 2015
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Ingår i: PolyRefNorth Seminar Abstract Book.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Liberation of fermentable sugars from cellulosic biomass during the course of enzymatic hydrolysis is one of the major obstacles in biorefineries due to high cost of enzymes. Enzymatic hydrolysis of cellulosic biomass is often incomplete. Understanding the limitations of the process would aid in improving the process. Among the limitations of enzymatic hydrolysis, structural properties of cellulose have a large effect on enzymatic hydrolysis efficiency. The aim of this study was to increase the understanding of the relation between enzymatic hydrolysis and structural properties of cellulosic substrates. In the current work, different cellulosic substrates were imaged and structural changes of cellulosic substrates were characterized in real-time in micrometer scale with nonlinear optical microscope, employing multi-photon excitation fluorescence (MPEF), second-harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) modalities. Solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C-NMR) was employed to quantify the spatial polymer distribution, accessible surface area, crystallinity and porosity in cellulosic substrates in nanometer scale. An array of cellulosic substrates was used in our study coming from softwood preparations used in pulp and paper industry and some model substrates.A strong correlation was found between the average pore size of the starting material and the enzymatic conversion yield. The degree of crystallinity was maintained during enzymatic hydrolysis of the cellulosic substrates. A substrate depended hydrolysis pattern was observed during enzymatic hydrolysis in real-time.
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| 22. |
- Saadatmand, Soheil, et al.
(författare)
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Turning hardwood dissolving pulp polysaccharide residual material into barrier packaging
- 2013
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 14:8, s. 2929-2936
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Tidskriftsartikel (refereegranskat)abstract
- Birch chips were subjected to pilot-scale pre-hydrolysis under various sets of conditions to mimic a pre-hydrolysis step in a dissolving pulp process. The process generates residual process liquor, a wood hydrolysate, and the treated chips may be directly utilized in a dissolving process. The wood hydrolysates were rich in xylan and utilized in the production of fully renewable films that provide very good oxygen barrier function and mechanical integrity also at high relative humidity. Membrane filtration had an effect in enriching higher molecular weight fractions from the hydrolysates, but noteworthy, a hydrolysate used in the crude state without any membrane filtration performed just as well as upgraded fractions in forming films providing acceptable tensile properties and a good barrier against oxygen permeation.
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| 23. |
- Yndigegn, Troels, et al.
(författare)
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Design and rationale of randomized evaluation of decreased usage of beta-blockers after acute myocardial infarction (REDUCE-AMI)
- 2022
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Ingår i: European Heart Journal - Cardiovascular Pharmacotherapy. - : Oxford University Press. - 2055-6837 .- 2055-6845. ; 9:2, s. 192-197
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Most trials showing benefit of beta-blocker treatment after myocardial infarction (MI) included patients with large MIs and are from an era before modern biomarker-based MI diagnosis and reperfusion treatment. The aim of the Randomized Evaluation of Decreased Usage of betabloCkErs after Acute Myocardial Infarction (REDUCE-AMI) trial is to determine whether long-term oral beta-blockade in patients with an acute MI and preserved left ventricular ejection fraction (EF) reduces the composite endpoint of death of any cause or recurrent MI.METHODS: It is a registry-based, randomized, parallel, open-label, multicenter trial performed at 38 centers in Sweden, one center in Estonia and six centers in New Zealand. About 5000 patients with an acute MI who have undergone coronary angiography and with EF ≥ 50% will be randomized to long-term treatment with beta-blockade or not. The primary endpoint is the composite endpoint of death of any cause or new non-fatal MI. There are several secondary endpoints, including all-cause death, cardiovascular death, new MI, readmission because of heart failure and atrial fibrillation, symptoms, functional status, health related quality of life after 6-10 weeks and after 1 year of treatment. Safety endpoints are bradycardia, AV-block II-III, hypotension, syncope or need for pacemaker, asthma or chronic obstructive pulmonary disease and stroke.CONCLUSION: The results from REDUCE-AMI will add important evidence regarding the effect of beta-blockers in patients with MI and preserved EF and may change guidelines and clinical practice.
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