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1.	Dérand, Helene, et al. (author) Pol(ethylene glycol) Graft Copolymers Containing Carboxylic Acid Groups: Aggregation and Viscometric Properties in Aqueous Solution 1996 In: Macromolecules. - 0024-9297. ; 29:27, s. 8770-8775 Journal article (peer-reviewed)abstract Poly(ethylene glycol) monomethyl ethers (MPEG) were grafted on copolymers of maleic anhydride and styrene, methyl methacrylate, and ethylhexyl methacrylate, respectively. Hydrolysis of the remaining anhydride residues gave graft copolymers carrying a large number of carboxylic acid groups along the main chains. The properties in aqueous solutions of these graft copolymers were studied with respect to aggregation behavior and viscometric properties, Aggregation of the polymers was examined by quasi-elastic light scattering and now field-flow fractionation in water and KCl solution. Both methods showed that the anionic graft copolymers mainly were present as single molecules in pure water, with a minor fraction of aggregates. In KCI solution, aggregates with average sizes of approximately 30 nm were the dominant species. In aqueous solution, the polymers exhibited polyelectrolyte behavior, i.e., a dramatic increase of the viscosity upon neutralization. Graft copolymers with hydrophobic groups in the backbone had lower viscosities.
2.	Wittgren, Bengt, et al. (author) Size characterization of a charged amphiphilic copolymer in solutions of different salts and salt concentrations using flow field-flow 1996 In: Langmuir. - 0743-7463. ; 12:25, s. 5999-6005 Journal article (peer-reviewed)abstract The aggregation behavior of a charged amphiphilic graft copolymer, prepared from poly(styrene-co-methyl methacrylate-co-maleic anhydride) and poly(ethylene oxide) monomethyl ether, was studied using flow field-flow fractionation (flow FFF). This method determines the hydrodynamic size of aggregates. The polymer was shown to have a complex aggregation behavior in aqueous solutions containing salt. This was expressed in the formation of differently sized structures, from single polymer chains to large polymolecular aggregates. The polymer changed its aggregation ability in the presence of different salts and salt concentrations, as reflected by changes in hydrodynamic size. Three different salts were tested: potassium chloride, sodium sulfate, and sodium phosphate. Even at micromolar concentrations of sodium sulfate, a pronounced aggregation was observed, probably due to reduced charge repulsion. At higher concentrations of the ''salting-out'' salts, the hydrodynamic size increased rapidly, reflecting the reduced solubility of the hydrophilic parts of the polymer, i.e. the poly(ethylene oxide) grafts. Sodium sulfate, and sodium phosphate in particular, had a stronger influence on polymer aggregation than potassium chloride. This agrees with current knowledge of electrolytic effects on poly(ethylene oxide) solutions. Flow FFF was found to be a suitable characterization technique for these complex systems, rapidly and efficiently separating different polymer aggregate populations ranging from a few nanometers up to 0.1 mu m.
3.	Andersson, M, et al. (author) Size and Structure Characterization of Ethylhydroxyethyl Cellulose by the Combination of Field-Flow Fractionation with Other Techniques. Investigation of Ultralarge Components 2004 In: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 5:1, s. 97-105 Journal article (peer-reviewed)abstract Ethylhydroxyethyl cellulose (EHEC) of three different viscosity classes (EHEC I, II, and III) was analyzed by programmed cross-flow asymmetrical flow field-flow fractionation coupled to multiangle light scattering and refractive index detectors to determine their size and molar mass distribution. Two size populations were detected in the two lower viscosity classes, EHEC I and II, one high molar mass and one ultrahigh molar mass (UHM). The two covered molar masses from 104 up to 109 g·mol-1. The highest viscosity class EHEC III was less size-dispersed covering molar masses from 5 × 105 to 5 × 107 g·mol-1. Filtering of the EHEC II solution removed small amounts of compact UHM material. Enzyme treatments were performed on EHEC II to further characterize it. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and anion ion-exchange chromatography coupled to pulsed amperometric detection showed that the UHM component contained EHEC.
4.	ARNELL, MAGNUS (author) Performance Assessment of Wastewater Treatment Plants : Multi-Objective Analysis Using Plant-Wide Models 2016 Doctoral thesis (other academic/artistic)abstract As the knowledge about anthropogenic impacts of climate change has grown, the awareness of the contributions from treatment of wastewater has widened the scope for wastewater treatment plants (WWTPs). Not only shall ever stricter effluent constraints be met, but also energy efficiency be increased, greenhouse gases mitigated and resources recovered. All under a constant pressure on costs. The main objective of this research has been to develop a plant-wide modelling tool to evaluate the performance of operational strategies for multiple objectives at the plant and for off-site environmental impact. The plant-wide model platform Benchmark Simulation Model no. 2 (BSM2) has been modified to improve the evaluation of energy efficiency and include greenhouse gas emissions. Furthermore, the plant-wide process model has been coupled to a life cycle analysis (LCA) model for evaluation of global environmental impact. For energy evaluation, a dynamic aeration system model has been adapted and implemented. The aeration model includes oxygen transfer efficiency, dynamic pressure in the distribution system and non-linear behaviour of blower performance. To allow for modelling of energy recovery via anaerobic co-digestion the digestion model of BSM2 was updated with a flexible co-digestion model allowing for dynamic co-substrate feeds. A feasible procedure for substrate characterisation was proposed. Emissions of the greenhouse gases CO2, CH4 and N2O were considered. The bioprocess model in BSM2 was updated with two-step nitrification, four-step denitrification and nitrifier denitrification to capture N2O production. Fugitive emissions of the three gases were included from digestion, cogeneration and sludge storage. The models were tested in case studies for the three areas of development: aeration, co-digestion and greenhouse gas production. They failed to reject the hypothesis that dynamic process models are required to assess the highly variable operations of wastewater treatment plants. All parts were combined in a case study of the Käppala WWTP in Lidingö, Sweden, for comparison of operational strategies and evaluation of stricter effluent constraints. The averaged model outputs were exported to an LCA model to include off-site production of input goods and impact of discharged residues and wastes. The results reveal trade-offs between water quality, energy efficiency, greenhouse gas emissions and abiotic depletion of elemental and fossil resources. The developed tool is generally applicable for WWTPs and the simulation results from this type of combined models create a good basis for decision support.
5.	Axelsson, Bodil, 1965-, et al. (author) Skärningspunkter och glapp i länkat, delat och nätverkat kulturarv 2017 Reports (other academic/artistic)abstract Idag delar arkiv, museer och bibliotek en och samma utmaning – gränserna mellan dem och mellan vardagsliv och kulturarvsinstitutioner blir allt mer porösa när digitala miljöer får större betydelse för hur människor, miljöer och kulturarvspraktiker knyts samman. Redan utpekade kulturarv får nya sammanhang och nya former för framspringande kulturarv skapas. I det här projektet studeras de skärningspunkter och glapp som uppstår mellan kulturarvsmyndigheter och identitetspolitiskt kulturarvsskapande bland människor i platsbaserade gemenskaper likaväl som bland dem som förenas av funktionsnedsättning, sexualitet och könsuttryck, etnisk tillhörighet eller religion.
6.	Fitzpatrick, Fiona, et al. (author) NMR, cloud-point measurements and enzymatic depolymerization: Complementary tools to investigate substituent patterns in modified celluloses 2006 In: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 7:10, s. 2909-2917 Journal article (peer-reviewed)abstract The substituent patterns of some chemically modified celluloses were characterized as a function of their size distribution, using size-exclusion chromatography coupled to both nuclear magnetic resonance spectroscopy (NMR) and cloud-point measurements. Intact and enzymatically hydrolyzed methyl cellulose (MC) was fractionated according to size, and the level of substitution of the fractions was measured off-line using NMR. Clouding behavior was also measured as a function of size. Clear differences between hydrolyzed and nonhydrolyzed samples were observed using both techniques. For samples that had been selectively hydrolyzed using cellulose-degrading enzymes, NMR data showed a direct link between the degree of degradation and the level of substitution. Differences in the clouding behavior highlighted changes in substituent levels and substituent patterns across the size distribution. The techniques gave valuable and somewhat complementary information on the substituent distributions of the samples before and after enzymatic hydrolysis.
7.	Johnson, Louis Banka, et al. (author) Combination of pre-operative radiotherapy and surgery suppresses local accumulation of collagen and TGF-beta 1 in rats 2006 In: Journal of Surgical Research. - : Elsevier BV. - 1095-8673 .- 0022-4804. ; 133:2, s. 136-142 Journal article (peer-reviewed)abstract Background. The systemic and local tissue repair responses of radiation in combination with surgery are still unclear. We have studied the effect of fractionated pre-operative radiotherapy with or without subsequent laparotomy on collagen accumulation using a rodent model. Materials and methods. Thirty-two male Sprague-Dawley rats were divided into four groups (eight rats per group): 1) sham radiation and sham laparotomy (control); 2) sham radiation and laparotomy; 3) radiation and sham laparotomy; and 4) radiation followed by laparotomy. Expanded polytetrafluoroethylene (ePTFE) tubes were implanted subcutaneously in the abdominal wall in the radiotherapy field and on the back outside the radiotherapy field day 0. The abdomen (3 cm x 4 cm) was irradiated day 3 (10 Gy) and again day 7 (10 Gy). On day 10, implants were extirpated, laparotomy undertaken in groups 2 and 4 and new ePTFE tubes implanted subcutaneously. The second implants were extirpated on day 20. Implants were analyzed for hydroxyproline, total protein and transforming growth factor-ss 1 (TGF-ss 1) levels. Results. On day 10, hydroxyproline (P < 0.05) and TGF-ss 1 (P < 0.001) were lower in ePTFE tubes in irra-diated compared with non-irradiated rats. On day 20, the abdominal ePTFE hydroxyproline remained low (P < 0.001) in animals subjected to laparotomy and pre-operative irradiation while hydroxyproline levels of rats subjected to irradiation only were similar to controls. The effects of radiation on hydroxyproline were confined to the irradiated abdominal area. There was a positive correlation between hydroxyproline and TGF-ss 1 levels in the abdominal wall implant day 20 (r = 0.53, P < 0.005). Conclusion. A clinically relevant fractionated radiation scheme reduced subcutaneous collagen accumulation pre-operatively and profoundly within the radiation field post-operatively after laparotomy, possibly because of lowered TGF ss 1 levels. (c) 2006 Elsevier Inc. All rights reserved.
8.	Johnson, Louis Banka, et al. (author) Radiation enteropathy and leucocyte-endothelial cell reactions in a refined small bowel model 2004 In: BMC Surgery. - : Springer Science and Business Media LLC. - 1471-2482. ; 4 Journal article (peer-reviewed)abstract BACKGROUND: Leucocyte recruitment and inflammation are key features of high dose radiation-induced tissue injury. The inflammatory response in the gut may be more pronounced following radiotherapy due to its high bacterial load in comparison to the response in other organs. We designed a model to enable us to study the effects of radiation on leucocyte-endothelium interactions and on intestinal microflora in the murine ileum. This model enables us to study specifically the local effects of radiation therapy. METHOD: A midline laparotomy was performed in male C57/Bl6 mice and a five-centimetre segment of ileum is irradiated using the chamber. Leucocyte responses (rolling and adhesion) were then analysed in ileal venules 2 - 48 hours after high dose irradiation, made possible by an inverted approach using intravital fluorescence microscopy. Furthermore, intestinal microflora, myeloperoxidase (MPO) and cell histology were analysed. RESULTS: The highest and most reproducible increase in leucocyte rolling was exhibited 2 hours after high dose irradiation whereas leucocyte adhesion was greatest after 16 hours. Radiation reduced the intestinal microflora count compared to sham animals with a significant decrease in the aerobic count after 2 hours of radiation. Further, the total aerobic counts, Enterobacteriaceae and Lactobacillus decreased significantly after 16 hours. In the radiation groups, the bacterial count showed a progressive increase from 2 to 24 hours after radiation. CONCLUSION: This study presents a refinement of a previous method of examining mechanisms of radiation enteropathy, and a new approach at investigating radiation induced leucocyte responses in the ileal microcirculation. Radiation induced maximum leucocyte rolling at 2 hours and adhesion peaked at 16 hours. It also reduces the microflora count, which then starts to increase steadily afterwards. This model may be instrumental in developing strategies against pathological recruitment of leucocytes and changes in intestinal microflora in the small bowel after radiotherapy.
9.	Korner, Anna, et al. (author) Influence of Different Polymer Types on the Overall Release Mechanism in Hydrophilic Matrix Tablets 2009 In: Molecules. - : MDPI AG. - 1420-3049. ; 14:8, s. 2699-2716 Journal article (peer-reviewed)abstract The effect of three different types of polymer chain structures on the polymer release from hydrophilic matrix tablets was investigated by comparing a synthetic semi-crystalline linear polymer (PEO), a branched amorphous polysaccharide (dextran) and an amorphous substituted cellulose derivative (HPMC). The polymer release rates for tablets containing mixtures of high and low molecular weight grades in different ratios were determined by using a modified USP II method and a SEC-RI chromatography system. The results showed that independent of polymer type: (i) plots of the release versus time had similar shapes, (ii) the release of long and short polymer chains was equal and no fractionation occurred during the release and (iii) the release rate could be related to the average intrinsic viscosity of the polymer mixtures. This confirms the hypothesis that the release rate can be related to a constant viscosity on the surface of the hydrophilic matrix tablet and that it is valid for all the investigated polymers.
10.	Körner, Anna, et al. (author) Molecular Information on the Dissolution of Polydisperse Polymers: Mixtures of Long and Short Poly(ethylene oxide). 2005 In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 109:23, s. 11530-11537 Journal article (peer-reviewed)abstract Abstract:A systematic study of the dissolution of dry, polydisperse poly(ethylene oxide) (PEO) samples, obtained from mixtures of low-molecular-weight and high-molecular-weight PEO, was made. During the dissolution process, the individual release of the low- and high-molecular-weight fractions was monitored. The high-molecular-weight/low-molecular-weight ratio controls the release rate, and the fraction of high-molecular-weight polymers dominates the effect on the overall release rate in mixed PEO tablets. Both fractions are released at the same rate during the main part of the dissolution process; however, during the initial dissolution period a fractionation occurs. The release rate is not a unique function of the average molecular weight of the polymer, but also depends on the polydispersity. By contrast, the average dimension of a polymer coil, as given by the intrinsic viscosity, gives a good prediction of the release rate irrespective of the polydispersity or details of the molecular weight distribution.
11.	Körner, Anna, et al. (author) Tuning the polymer release from hydrophilic matrix tablets by mixing short and long matrix polymers 2005 In: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 1520-6017 .- 0022-3549. ; 94:4, s. 759-769 Journal article (peer-reviewed)abstract In this work a rotating disc method was developed for studying the dissolution process of bimodal polymer tablets, whose dissolution rates have been tuned by mixing low-molecular weight and high-molecular weight samples of poly(ethylene oxide) in various proportions. The tablets were prepared along different routes, by mixing the polymer fractions as powders or by mixing on a molecular level so that the effect of tablet heterogeneity could be assessed, but also by purifying the original powders so the effect of additives could be determined. When the mixed tablet was dominated by the low-molecular weight fraction, a faster dissolution was observed for the tablet mixed at the powder level. In those cases small gel pieces were released from the tablet during the whole dissolution process. As long as no gel piece erosion was observed, it did not matter if the two polymer fractions were blended on the molecular level or on the powder level, the steady-state dissolution rate was the same. The presence of small amounts of additives in the nonpurified commercial samples had no significant effect on the tablet dissolution within the uncertainty of the experiment.
12.	Leeman, Mats, et al. (author) Programmed cross flow asymmetrical flow field-flow fractionation for the size separation of pullulans and hydroxypropyl cellulose 2006 In: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1134:1-2, s. 236-245 Journal article (peer-reviewed)abstract Different functions for the programming of the cross flow in asymmetrical flow field-flow fractionation were studied with the aim to find the flow conditions most suitable for the molar mass distribution analysis of high molecular weight polysaccharides. A mixture of four differently sized pullulans covering the molar mass range 5.8 x 10(3)-1.6 x 106 g mol(-1) were used as a model sample. Two types of programs were studied, linear and exponential decays, both with and without initial periods of a constant cross flow. For comparison, nonprogrammed runs, i.e. using constant cross flow, were studied. It was found that exponentially decaying cross flow gave the most uniform molar mass selectivity across the fractogram. The programmed cross flow was applied to the molar mass distribution analysis of a technical quality of hydroxypropyl cellulose. (c) 2006 Elsevier B.V. All rights reserved.
13.	Momcilovic, Dane, et al. (author) Improved MALDI-TOF-MS analysis of partially depolymerised methyl cellulose by reducing end derivatisation 2002 In: Proceedings 50th ASMS Conference on Mass Spectrmetry and Allied Topics. ; , s. 421-422 Conference paper (peer-reviewed)abstract The depolymerized methyl cellulose was analyzed, using improved MALDI-TOF-MS by reducing the end derivatization. The methyl cellulose was depolymerized to give methylated oligo-(1->4)-β-D-anhydroglucoses (M-oligo-AG). To reduce the errors during measurement of degree of substitution (DS), M-oligo-AG was derivatized with Girard's T reagent performed on an equimolar mixture of maltooligosaccharides. The GT-derivatized M-oligo-AG (GT-M-oligo-AG) formed singly charged molecular ions with peaks at m/z values 91 higher than the corresponding peaks of M-oligo-AG. The results show that for GT-M-oligo-AG the relative signal intensities for DP=1 and 2 were increased significantly.
14.	Momcilovic, Dane, et al. (author) Sample preparation effects in matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry of partially depolymerised methyl cellulose 2003 In: Rapid Communications in Mass Spectrometry. - : Wiley. - 1097-0231 .- 0951-4198. ; 17:11, s. 1116-1124 Journal article (peer-reviewed)abstract Methyl cellulose (MC) was partially depolymerised and the oligomers thus obtained were studied by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). The depolymerisation was either enzymatic or acidic. Fractions of enzymatically depolymerised MC were collected from size-exclusion chromatography and subjected to a sample preparation investigation. Several MALDI matrices and solvents were evaluated. The results showed that the solvent choice had a significant effect on the measured degree of substitution (DS). Aprotic solvents produced higher DS values, which was most likely due to poor solubility of species with low DS. The obtained signal intensity, however, did not correlate with the solubility but seemed to be more dependent on certain matrix/solvent combinations. All the matrices attempted produced mass spectra with sufficient signal intensity for accurate peak area calculation. The choice of matrix did not have any significant effect on the measured DS. Sample spots obtained from organic solvents had a more homogeneous distribution of the analyte and smaller crystals than those obtained from water. This increased both the reproducibility and peak resolution and in addition the analysis time was shorter. DS measurements were performed on two acidically depolymerised MCs with different nominal DS values. It was easy to distinguish between the two MCs, and the measured DS values agreed well with the values supplied by the manufacturers. Copyright © 2003 John Wiley & Sons, Ltd.
15.	Polistena, Andrea, et al. (author) Local radiotherapy of exposed murine small bowel : Apoptosis and inflammation 2008 In: BMC Surgery. - : Springer Science and Business Media LLC. - 1471-2482. ; 8 Journal article (peer-reviewed)abstract Background. Preoperative radiotherapy of the pelvic abdomen presents with complications mostly affecting the small bowel. The aim of this study was to define the features of early radiation-induced injury on small bowel. Methods. 54 mice were divided into two groups (36 irradiated and 18 sham irradiated). Animals were placed on a special frame and (in the radiated group) the exteriorized segment of ileum was subjected to a single absorbed dose of 19 or 38 Gy radiation using 6 MV high energy photons. Specimens were collected for histology, immunohistochemistry (IHC) and ELISA analysis after 2, 24 and 48 hours. Venous blood was collected for systemic leucocyte count in a Burker chamber. Results. Histology demonstrated progressive infiltration of inflammatory cells with cryptitis and increased apoptosis. MIP-2 (macrophage inflammatory protein) concentration was significantly increased in irradiated animals up to 48 hours. No significant differences were observed in IL-10 (interleukin) and TNF-α (tumour necrosis factor) levels. IHC with CD45 showed a significant increase at 2 hours of infiltrating leucocytes and lymphocytes after irradiation followed by progressive decrease with time. Caspase-3 expression increased significantly in a dose dependent trend in both irradiated groups up to 48 hours. Conclusion. Acute small bowel injury caused by local irradiation is characterised by increased apoptosis of crypt epithelial cells and by lymphocyte infiltration of the underlying tissue. The severity of histological changes tends to be dose dependent and may affect the course of tissue damage.
16.	Polistena, Andrea, et al. (author) Matrilysin Expression Related to Radiation and Microflora Changes in Murine Bowel. 2011 In: The Journal of surgical research. - : Elsevier BV. - 1095-8673 .- 0022-4804. ; 167, s. 137-143 Journal article (peer-reviewed)abstract BACKGROUND: Matrilysin (MMP-7) elevation after radiotherapy is shown in humans. Matrilysin regulates certain cytokines and the production of bactericidal proteins when the mucosa is exposed to bacterial antigens. We investigate the effect of irradiation on matrilysin and microflora in murine bowel, after modulation with antibiotics. METHODS: Animals were divided into two different groups a radiation group (72 animals) and sham radiation group (36 animals). Animals were divided into smaller groups of six according to radiation dose (19 or 38 Gy or sham). Seven days before radiotherapy ampicillin 500 mg/kg/d was administered intramuscularly, in the antibiotic groups. An exteriorized segment of ileum was subjected to single high dose radiation (19 or 38 Gy). Samples were collected 2, 24, and 48 h and analyzed for microflora, MIP-2, TGF-β, and MMP-7. RESULTS: The combination of antibiotics and irradiation leads to an early significant reduction of bacteria, down-regulates MIP-2, up-regulates TGF-β and elevation of MMP-7 to levels achieved by antibiotics or irradiation alone. Lactobacilli were reduced to non-existent levels after antibiotics. CONCLUSIONS: Pretreatment with Ampicillin before irradiation and laparotomy in a murine model leads to Matrilysin over-expression as achieved by radiotherapy alone. Microfloral regulation does not affect MMP-7 stimulation after surgical or radiological trauma. Radiotherapy overrides the effect of antibiotics leading to an up-regulation of MMP-7, TGF-β and MIP-2 expression between 24 h and 48 h.
17.	Richardson, Sara, et al. (author) Initial Characterization of Ethyl(hydroxyethyl) Cellulose Using Enzymic Degradation and Chromatographic Methods 2002 In: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 3:6, s. 1359-1363 Journal article (peer-reviewed)abstract Two different ethyl(hydroxyethyl) cellulose (EHEC) samples were characterized by size-exclusion chromatography (SEC) with multiangle light scattering (MALS) detection and high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD). The aim of the study was to investigate the molar mass distribution and the heterogeneity of the substituent distribution, factors that are thought to affect the functional properties of EHEC. The presence of blocks of unsubstituted glucose units was studied by enzymic degradation of EHEC by two different endoglucanases from Trichoderma reesei. The SEC-MALS analysis of the hydrolysis products showed that both enzymes were strongly inhibited by the large number of substituents along the cellulose chain. However, as the weight-average molar mass was reduced from approximately 360 000 to 80 000 g/mol in one of the polymers and from 770 000 to 60 000 g/mol in the other polymer, it was suggested that both samples were composed of some unsubstituted regions where the enzymes got access to the glucosidic bonds. The amount of glucose released upon endoglucanase hydrolysis was determined by HPAEC-PAD, which gave information on the homogeneity of the substituent distribution. The production of unsubstituted glucose units indicated that one of the polymers had a more uneven distribution compared with the other. It was demonstrated that chemical characterization of EHEC is a complex task, which requires an analytical approach involving numerous different methods and techniques.
18.	Schagerlöf, Herje, et al. (author) Substituent distribution and clouding behavior of hydroxypropyl methyl cellulose analyzed using enzymatic degradation 2006 In: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 7:12, s. 3474-3481 Journal article (peer-reviewed)abstract The distribution of substituents along the polymer backbone will have a strong influence on the properties of modified cellulose. Endoglucanases were used to degrade three different batches of hydroxypropyl methyl cellulose ( HPMC) derivatives with similar chemical properties. The phase separation of the HPMCs as a function of temperature, i.e., the clouding behavior, was analyzed prior to degradation. The total amount of unsubstituted glucose was determined using total acid hydrolysis followed by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The products after enzymatic degradation were analyzed with size-exclusion chromatography with online multiangle light scattering and refractive index detection and also with reducing end determination. To further characterize the formed products, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was employed for analysis of short-chained oligosaccharides. The different endoglucanases showed varying degradation capability of HPMC derivatives, depending on structure of the active site. The investigated HPMCs had different susceptibility to degradation by the endoglucanases. The results showed a difference in substituent distribution between HPMC batches, which could explain the differing clouding behaviors. The batch with the lowest cloud point was shown to contain a higher number of non-degradable, highly substituted regions.
19.	Viridén, Anna, 1977, et al. (author) Influence of Substitution Pattern on Solution Behavior of Hydroxypropyl Methylcellulose 2009 In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 10:3, s. 522-529 Journal article (peer-reviewed)abstract Industrially produced hydroxypropyl Me cellulose (HPMC) is a chem. heterogeneous material, and it is thus difficult to predict parameters related to function on the basis of the polymer's av. chem. values. In this study, the soln. behavior of 7 HPMC batches was correlated to the mol. wt., degree of substitution, and substituent pattern. The initial onset of phase sepn., so-called clouding, generally followed an increased av. mol. wt. and degree of substitution. However, the slope of the clouding curve was affected by the substitution pattern, where the heterogeneously substituted batches had very shallow slopes. Further investigations showed that the appearance of a shallow slope of the clouding curve was a result of the formation of reversible polymer structures, formed as a result of the heterogeneous substituent pattern. These structures grew in size with temp. and concn. and resulted in an increase in the viscosity of the solns. at higher temps.
20.	Viridén, Anna, 1977, et al. (author) Investigation of critical polymer properties for polymer release and swelling of HPMC matrix tablets 2009 In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 36:2-3, s. 297-309 Journal article (peer-reviewed)abstract Four different HPMC batches were characterized to investigate properties related to crit. functionality for their use in hydrophilic matrix tablets. In this study, the HPMC batches were chem. characterized and correlated to the behavior of pure HPMC tablets. Parameters such as the mol. wt., viscosity, intrinsic viscosity and radius of gyration were kept in a rather limited range, which resulted in a weak correlation to polymer release and degree of swelling. The hydrophilic/hydrophobic character of the HPMC samples was elucidated by the degree of substitution and by the clouding behavior, where an increased hydrophilicity increased the tablet swelling. This phenomenon was interpreted in a refined model for water transport into HPMC tablets. A five times slower polymer release and a considerably larger degree of swelling were found for one batch of HPMC tablets compared to the others, although the characterized av. polymer parameters were in the same range. However, the conformation plot displayed a fraction with compact aggregates. In conclusion, the existence of aggregates in aq. soln. seems to perturb the functionality of HPMC tablets and it seems important to understand and characterize these aggregates to fully predict the polymer release and swelling of HPMC tablets.
21.	Viridén, Anna, 1977, et al. (author) Model drug release from matrix tablets composed of HPMC with different substituent heterogeneity 2010 In: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 401:1-2, s. 60-67 Journal article (peer-reviewed)abstract The release of a model drug substance, methylparaben, was studied in matrix tablets composed of hydroxypropyl methylcellulose (HPMC) batches of the USP 2208 grade that had different chemical compositions. It was found that chemically heterogeneous HPMC batches with longer sections of low substituted regions and lower hydroxypropoxy content facilitated the formation of reversible gel structures at a temperature as low as 37 degrees C. Most importantly, these structures were shown to affect the release of the drug from matrix tablets, where the drug release decreased with increased heterogeneity and a difference in T80 values of 7 h was observed between the compositions. This could be explained by the much lower erosion rate of the heterogeneous HPMC batches, which decreased the drug release rate and also released the drug with a more diffusion based release mechanism compared to the less heterogeneous batches. It can therefore be concluded that the drug release from matrix tablets is very sensitive to variations in the chemical heterogeneity of HPMC.
22.	Viridén, Anna, 1977, et al. (author) Release of theophylline and carbamazepine from matrix tablets - Consequences of HPMC chemical heterogeneity 2011 In: European Journal of Mineralogy. - : Elsevier BV. - 0935-1221. ; 78:3, s. 470-479 Journal article (peer-reviewed)abstract The release of theophylline and carbamazepine from matrix tablets composed of microcrystalline cellulose, lactose and hydroxypropyl methylcellulose (HPMC) was studied. The aim was to investigate the effect of different substituent heterogeneities of HPMC on the drug release from matrix tablets composed of either 35% or 45% HPMC. The release of the poorly soluble carbamazepine was considerably affected by the HPMC heterogeneity, and the time difference at 80% drug release was more than 12 h between the formulations of different HPMC batches. This was explained by slower polymer erosion of the heterogeneous HPMC and the fact that carbamazepine was mainly released by erosion. In addition, results from magnetic resonance imaging showed that the rate of water transport into the tablets was similar. This explained the comparable results of the release of the sparingly soluble theophylline from the two formulations even though the polymer erosion and the swelling of the tablets were considerably different. Thus, it can be concluded that the drug release was highly affected by the substituent heterogeneity, especially in the case of carbamazepine, which was released mainly by erosion. (C) 2011 Elsevier B.V. All rights reserved.
23.	Viridén, Anna, 1977, et al. (author) The consequence of the chemical composition of HPMC in matrix tablets on the release behaviour of model drug substances having different solubility 2011 In: European Journal of Pharmaceutics and Biopharmaceutics. - : Elsevier BV. - 1873-3441 .- 0939-6411. ; 77:1, s. 99-110 Journal article (peer-reviewed)abstract This study investigates the effect of the chemical heterogeneity of hydroxypropyl methylcellulose (HPMC) on the release of model drug substances from hydrophilic matrix tablets. The hypothesis was that the release of drug substances could be influenced by possible interactions with HPMC batches having different chemical heterogeneity. The cloud point of the most heterogeneous batch was more affected by the model drug substances, methylparaben and butylparaben, and most by butylparaben with the lowest solubility. The different clouding behaviour was explained by the heterogeneously substituted batches being more associative and the more lipophilic butylparaben being able to interact more efficiently with the hydrophobic HPMC transient crosslinks that formed. Interestingly, tablet compositions of the heterogeneously substituted HPMC batches released the more soluble methylparaben at lower rates than butylparaben. The explanation is that the hydrophobic HPMC interactions with butylparaben made the gel of the tablet less hydrated and more fragile and therefore more affected by erosional stresses. In contrast, drug release from compositions consisting of the more homogeneously substituted batches was affected to a minor extent by the drugs and was very robust within the experimental variations. The present study thus reveals that there can be variability in drug release depending on the lipophilicity of the drug and the substituent heterogeneity of the HPMC used.
24.	Viridén, Anna, 1977, et al. (author) The effect of chemical heterogeneity of HPMC on polymer release from matrix tablets 2009 In: European journal of pharmaceutical sciences official journal of the European Federation for Pharmaceutical Sciences. - : Elsevier BV. - 1879-0720. ; 36:4-5, s. 392-400 Journal article (peer-reviewed)abstract Polymer release from hydrophilic matrix tablets, composed of hydroxypropyl methylcellulose, was studied for seven different polymer batches. A time difference of more than 80h between fully dissolved tablets was noticed although the batches were of the same pharmaceutical substituent (USP 2208) and viscosity (100 cps) grade. To find the functionality related parameters for polymer release from hydrophilic matrix tablets the polymer samples were characterised according to size and chemical composition. The size of the polymers was characterised by size-exclusion chromatography with multi-angle light scattering and refractive index detection. The average amount of substituents was measured with nuclear magnetic resonance and the distribution of the substituents along the cellulose chain was determined with high-performance anion-exchange chromatography with pulsed amperometric detection after acid and enzymatic hydrolysis. The results indicated that other types of interactions apart from entanglements were present between the polymer chains, which seemed to affect the polymer release. Most importantly, this study has shown a correlation between the polymer release and the substituent pattern, where the samples with slow release also were more heterogeneously substituted along the polymer chain. From this we can conclude that polymer release is very sensitive to alterations in chemical composition.
25.	Viridén, Anna, 1977, et al. (author) The effect of substitution pattern of HPMC on polymer release from matrix tablets 2010 In: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 389:1-2, s. 147-156 Journal article (peer-reviewed)abstract The purpose of this study was to gain further understanding of how the substituent heterogeneity of hydroxypropyl methylcellulose, HPMC, affects the polymer release from hydrophilic matrix tablets. The hypothesis was that the heterogeneous substituent pattern facilitated hydrophobic interactions that increased the viscosity and therefore affected the release rate to a major extent. Polymer tablets were prepared from three heterogeneously substituted HPMC batches of the same substituent (2208) and viscosity (100 cps) grade. To elucidate the hypothesis, fractions of both the dissolved polymer and the tablet residue were collected from the dissolution bath and further characterised. The extensive characterisation showed that, although the dissolved bath fraction and the tablet residue had a similar average degree of substitution, the residue was more heterogeneously substituted. It was further revealed that the heterogeneous substituent pattern of the tablet residue facilitated the formation of soluble gel-like components already at room temperature, which increased the viscosity. The viscosity increased by 150% at temperatures correlated to the dissolution bath, and it was thus concluded that the gel-like components grew in size with temperature. Finally, much lower release rates were obtained by tablets composed of the residue compared to tablets composed of the bath fraction, which clarified the hypothesis.
26.	Wittgren, Bengt (author) ABM-sektorns idé utifrån ABM-folket och dess utbildning 2005 In: Om ABM. - Härnösand : ABM resurs, länsmuseet Västernorrland. - 9185222062 ; , s. 93-106 Book chapter (other academic/artistic)
27.	Wittgren, Bengt, 1960- (author) Katalogen – nyckeln till museernas kunskap? : Om dokumentation och kunskapskultur i museer 2013 Doctoral thesis (other academic/artistic)abstract In the 1990s, the MLA sector – archives, libraries, museums – was defined as a comprehensive sector. One of the reasons for this was the belief that the digitizing of institutional collections and catalogues would provide a seamless access to the cultural heritage for the general public. No one would any longer need to know in which institution a certain object was kept; everything would be available on the Internet.The questions in this dissertation depart from the expectations in the late 1900s aimed at the available systems in the MLA sector for the management and storage of information and at knowledge maintained in such systems. My point of departure is the idea that access to collections in the MLA sector – real or digital – is made possible through the catalogues. It is in the catalogues that the sector orders data and preserves knowledge collected about the objects. My most important conclusions deal with the management and production of knowledge in the sector. The data systems generally used in the MLA sector lack the indulgence needed to accommodate inherent variability of information. Systems must be based on exact sorting, uniform terminology and classification without deviations in spelling or interpretation.Furthermore, international projects and systems presuppose distinct translations between national terminologies and international classification systems to work for information retrievals.This is not the case with the museum systems here investigated, in opposition to, primarily, the libraries. The museum systems are characterised as distinctive instead of following uniformity principles and national or international taxonomies.An important conclusion about knowledge processing and knowledge production in the MLA sector is that the value of compiling digitalised data from many museums is limited. It is not possible to realize the political goal other than at a superficial level.The conclusions in a comparison between the three professional groups are that in the beginning of the 21th century an extensive part of the antiquarians confirm a thought style, according to Ludwik Fleck, which has another direction than that of archivists and librarians. Throughout the 20th century or in the last decades of the 20th century the two latter groups professionalised their roles both through changes in education and through new professional requirements which led to positions and attitudes in their work other than what happened in the museum sector. Museums are mainly research institutions with members of staff who in many respects lack a focus on increased accessibility of collections. Challenges formulated for museums of cultural history by the cultural politics of the 1970s have not been answered with great flexibility.The investigation in this dissertation demonstrates that archives, libraries and museums in many respects continue to pursue activities according to a thought style which was formed during the first half of the 20th century. Their positions in society, their administrational practice and expectations from the general public constitute stabilising and preserving factors. The MLA sector is not as comprehensive as the policy makers want to believe.
28.	Wittgren, Bengt (author) Size Characterisation of Water-Soluble Polymers Using Asymmetrical Flow Field-Flow Fractionation 1997 Doctoral thesis (other academic/artistic)abstract Size, as expressed by molar mass, radius of gyration or hydrodynamic radius, for example, is a fundamental parameter of polymers in solution. Thus, there is a strong need for the characterisation of both the size and shape of polymers, particularly of those utilised in various industrial applications. In this thesis, a relatively novel technique, asymmetrical flow field-flow fractionation (flow FFF), was employed for the size charaterisation of water-soluble polymers of varying origin. The applicability of flow FFF for the size characterisation of a charged amphiphilic graft copolymer was tested first. The micellisation and aggregation behaviour of this copolymer was studied measuring hydrodynamic size in different salts at differing salt concentrations and pH by means of flow FFF. Hydrodynamic size was shown to increase dramatically when ionic strength was increased, due to the formation of large micelles and aggregates. Flow FFF was able here to rapidly characterise both single polymer molecules, of small hydrodynamic diameter (approximately 5 nm), and large aggregates, more than 100 nm in diameter. Combined with a multi-angle light scattering (MALS) detector, it could also be used for determining molar mass and radius of gyration. This possibility was first demonstrated for two model polysaccharides, dextrans and pullulans, of known molar mass and polydispersity. Flow FFF - MALS provided here measurements of molar mass in good agreement with the manufacturer's data. Flow FFF - MALS was then used for the characterisation of modified celluloses and carrageenans. For these polymers, displaying a complex solution behaviour and thus very diffucult to characterise, distributions of molar mass and radius of gyration were readily obtained. The importance of choosing appropriate experimental conditions so as to avoid artifacts was clearly demonstrated. For the carrageenans, very large structures, with a molar mass of several million, were found to be eluted in a reverse elution order in flow FFF.

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