| 1. |
- Guerova, G., et al.
(författare)
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National Status Reports
- 2020
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Ingår i: Advanced GNSS Tropospheric Products for Monitoring Severe Weather Events and Climate. - Cham : Springer International Publishing. - 9783030139001 ; , s. 403-481
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In this section a summary of the national progress reports is given. GNSS4SWEC Management Committee (MC) members provided outline of the work conducted in their countries combining input from different partners involved. In the COST Action paticipated member from 32 COST countries, 1 Near Neighbour Country and 8 Intrantional Partners from Australia, Canada, Hong Kong and USA. The text reflects the state as of 1 January 2018.
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| 2. |
- Potthast, W, et al.
(författare)
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Relative movements between the tibia and femur induced by external plantar shocks are controlled by muscle forces in vivo.
- 2011
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290 .- 1873-2380. ; 44:6, s. 1144-1148
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate the role of muscle activation on the relative motion between tibia and femur. Impacts were initiated under the heels of four volunteers in three different activation levels of muscles crossing the extended knee joint: 0%, 30% and 60% of previously performed maximal voluntary isometric contractions. Impact forces were measured and tibial and femoral accelerations and displacements were determined by means of accelerometry. The accelerometers were mounted on the protruding ends of intracortical pins, inserted into the distal aspect of the femur and proximal aspect of the tibia. Under the 0%-condition the impact force (475±64N) led to 2.3±1.2mm knee compression and to 2.4±1.9mm medio-lateral and 4.4±1.1mm antero-posterior shear. The impact forces increased significantly with higher activation levels (619±33N (30%), 643±147N (60%)), while the knee compression (1.5±1.2, 1.4±1.3mm) and both medio-lateral shear (1.8±1.4, 1.5±1.1mm) and antero-posterior shear (2.6±1.3, 1.5±1.1mm) were significantly reduced. This study indicated that muscles are effective in controlling the relative motion between tibia and femur when the knee is subjected to external forces.
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| 3. |
- Potthast, W, et al.
(författare)
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The influences of impact interface, muscle activity, and knee angle on impact forces and tibial and femoral accelerations occurring after external impacts
- 2010
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Ingår i: Journal of applied biomechanics. - : Human Kinetics. - 1065-8483 .- 1543-2688. ; 26:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to quantify relative contributions of impact interface, muscle activity, and knee angle to the magnitudes of tibial and femoral accelerations occurring after external impacts. Impacts were initiated with a pneumatically driven impacter under the heels of four volunteers. Impact forces were quantified with a force sensor. Segmental accelerations were measured with bone mounted accelerometers. Experimental interventions were hard and soft shock interfaces, different knee angles (0°, 20°, 40° knee flexion), and muscular preactivation (0%, 30%, 60% of maximal voluntary contraction) of gastrocnemii, hamstrings, and quadriceps. Greater knee flexion led to lower impact forces and higher tibial accelerations. Increased muscular activation led to higher forces and lower tibial accelerations. The softer of the two shock interfaces under study reduced both parameters. The effects on accelerations and forces through the activation and knee angle changes were greater than the effect of interface variations. The hardness of the two shock interfaces explained less than 10% of the variance of accelerations and impact forces, whereas knee angle changes explained 25–29%, and preactivation changes explained 35–48% of the variances. It can be concluded that muscle force and knee joint angle have greater effects in comparison with interface hardness on the severity of shocks on the lower leg.
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| 4. |
- Hasani, Merima, 1978, et al.
(författare)
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Cationization of Cellulose by Using N-Oxiranylmethyl-N-Methylmorpholinium Chloride and 2-Oxiranylpyridine as Etherification Agents
- 2009
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 114:3, s. 1449-1456
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Tidskriftsartikel (refereegranskat)abstract
- Cationization of cellulose under aqueous alkaline conditions was studied. Two new epoxy reagents, N-oxiranylmethyl-N-methylmorpolinitim chloride and 2-oxiranylpyridine, were used for preparation of cationic cellulose ethers. Using the first agent, cationic ethers were obtained in one step, whereas the latter one yielded a reactive intermediate used as a precursor for two different cationizations. Etherification with the commonly used 2,3-epoxypropyltrimethylammonium chloride was also performed and used as a reference reaction. By changing water content in the reaction mixture two groups cellulose ethers with different degrees of cationization were prepared. As expected, reducing the water content resulted in a higher degree of etherification and hence a more pronounced cationic character of the obtained ethers. Characterization by FTIR, elemental- and gravimetric analysis confirmed the formation of the desired ethers. Their ability to interact with water and adsorb the acid dye, methyl orange, was also studied, confirming further introduction of the cationic substituents and revealing different reactivities of the used epoxy reagents. From characterization, it could be concluded that N-oxiranylmethyl-N-methylmorpholinium chloride exhibits higher reactivity toward cellulose than both the reference compounds and 2-oxiranylpyridine. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 1449-1456, 2009
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| 5. |
- Hasani, Merima, 1978, et al.
(författare)
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Nano-cellulosic materials: The impact of water on their dissolution in DMAc/LiCl
- 2013
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 98:2, s. 1565-1572
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Tidskriftsartikel (refereegranskat)abstract
- The dissolution behaviour of disassociated cellulosic materials in N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) was investigated. The parameters monitored were chromatographic elution profiles and recovered mass by means of gel permeation chromatography (GPC) with RI detection. In order to elucidate the impact of the disassembly on cellulosic fibres, comparative studies were performed with the non-disassociated cellulose counterparts. The importance of the presence of water was addressed by Karl Fischer titration and solvent exchange experiments. Morphological changes during the dissolution process were studied by scanning electron microscopy (SEM). Dissolution of fibrillated cellulosic materials is impeded compared to the non-fibrillated material. This is a consequence of the high-surface-area fibrils prone to retain high amounts of water. Dissolution behaviour of nano-crystalline cellulosic materials appeared to be source-dependent. Due to the absence of entangled networks, these materials retain only water bound at the surface of the nano-crystallites, indicative of both the exposed surface area and solubility. The small cellulose nano-particles extracted from dissolving pulp show lower solubility compared to the large NCC particles from cotton.
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| 6. |
- Henniges, U., et al.
(författare)
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Electron Beam Irradiation of Cellulosic Materials-Opportunities and Limitations
- 2013
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 6:5, s. 1584-1598
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Tidskriftsartikel (refereegranskat)abstract
- The irradiation of pulp is of interest from different perspectives. Mainly it is required when a modification of cellulose is needed. Irradiation could bring many advantages, such as chemical savings and, therefore, cost savings and a reduction in environmental pollutants. In this account, pulp and dissociated celluloses were analyzed before and after irradiation by electron beaming. The focus of the analysis was the oxidation of hydroxyl groups to carbonyl and carboxyl groups in pulp and the degradation of cellulose causing a decrease in molar mass. For that purpose, the samples were labeled with a selective fluorescence marker and analyzed by gel permeation chromatography (GPC) coupled with multi-angle laser light scattering (MALLS), refractive index (RI), and fluorescence detectors. Degradation of the analyzed substrates was the predominant result of the irradiation; however, in the microcrystalline samples, oxidized cellulose functionalities were introduced along the cellulose chain, making this substrate suitable for further chemical modification.
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| 7. |
- Irbäck, A, et al.
(författare)
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Binary assignments of amino acids from pattern conservation
- 1997
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Ingår i: Protein Engineering. - : Oxford University Press (OUP). - 0269-2139. ; 10:9, s. 1013-1017
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a simple optimization procedure for assigning binary values to amino acids. The binary values are determined by a maximization of the degree of pattern conservation in groups of closely related protein sequences. The maximization is carried out at fixed composition. For compositions approximately corresponding to an equipartition of the residues, the optimal encoding is found to be strongly correlated with hydrophobicity. The stability of the procedure is demonstrated. Our calculations are based upon sequences in the SWISS-PROT database.
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| 8. |
- Irbäck, A, et al.
(författare)
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Design of sequences with good folding properties in coarse-grained protein models
- 1999
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Ingår i: Structure. - 0969-2126. ; 7:3, s. 60-347
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Designing amino acid sequences that are stable in a given target structure amounts to maximizing a conditional probability. A straightforward approach to accomplishing this is a nested Monte Carlo where the conformation space is explored over and over again for different fixed sequences; this requires excessive computational demand. Several approximate attempts to remedy this situation, based on energy minimization for fixed structure or high-T expansions, have been proposed. These methods are fast but often not accurate, as folding occurs at low T.RESULTS: We have developed a multisequence Monte Carlo procedure where both sequence and conformational space are simultaneously probed with efficient prescriptions for pruning sequence space. The method is explored on hydrophobic/polar models. First we discuss short lattice chains in order to compare with exact data and with other methods. The method is then successfully applied to lattice chains with up to 50 monomers and to off-lattice 20mers.CONCLUSIONS: The multisequence Monte Carlo method offers a new approach to sequence design in coarse-grained models. It is much more efficient than previous Monte Carlo methods, and is, as it stands, applicable to a fairly wide range of two-letter models.
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| 9. |
- Irbäck, A, et al.
(författare)
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Evidence for nonrandom hydrophobicity structures in protein chains
- 1996
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Ingår i: Proceedings of the National Academy of Sciences. - 0027-8424. ; 93:18, s. 8-9533
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Tidskriftsartikel (refereegranskat)abstract
- The question of whether proteins originate from random sequences of amino acids is addressed. A statistical analysis is performed in terms of blocked and random walk values formed by binary hydrophobic assignments of the amino acids along the protein chains. Theoretical expectations of these variables from random distributions of hydrophobicities are compared with those obtained from functional proteins. The results, which are based upon proteins in the SWISS-PROT data base, convincingly show that the amino acid sequences in proteins differ from what is expected from random sequences in a statistically significant way. By performing Fourier transforms on the random walks, one obtains additional evidence for nonrandomness of the distributions. We have also analyzed results from a synthetic model containing only two amino acid types, hydrophobic and hydrophilic. With reasonable criteria on good folding properties in terms of thermodynamical and kinetic behavior, sequences that fold well are isolated. Performing the same statistical analysis on the sequences that fold well indicates similar deviations from randomness as for the functional proteins. The deviations from randomness can be interpreted as originating from anticorrelations in terms of an Ising spin model for the hydrophobicities. Our results, which differ from some previous investigations using other methods, might have impact on how permissive with respect to sequence specificity protein folding process is-only sequences with nonrandom hydrophobicity distributions fold well. Other distributions give rise to energy landscapes with poor folding properties and hence did not survive the evolution.
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| 10. |
- Martinsson, Axel, 1992, et al.
(författare)
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Modification of softwood kraft pulp fibres using hydrogen peroxide at acidic conditions
- 2020
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 27:12, s. 7191-7202
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to provide softwood kraft pulp fibres with new functionalities by the introduction of carbonyl groups. Carbonyl groups are known to affect properties such as wet strength through the formation of covalent bonds, i.e. hemiacetals. The method developed involves oxidation using hydrogen peroxide at mildly acidic conditions. It was found that the carbonyl group content increased with both increasing temperature and residence time when oxidized at acidic conditions. The number of carboxylic groups, however, remained approximately constant. There was virtually no increase in carbonyl groups when oxidation was performed at alkaline conditions. The maximum increase in carbonyl groups was found at a residence time of 90 min, a reaction temperature of 85 °C and a pH of 4. These conditions resulted in an increase in carbonyl groups from 30 to 122 µmol/g. When formed into a sheet, the pulp oxidized at acidic conditions proved to maintain its structural integrity at aqueous conditions. This indicates the formation of hemiacetal bonds between the introduced carbonyl groups and the hydroxyl groups on the carbohydrate chains. Thus, a possible application for the method could be fibre modification during the final bleaching stage of softwood kraft pulp, where the wet strength of the pulp could be increased.
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