| 1. |
- Taherzadeh, M.J., et al.
(författare)
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Pretreatment of lignocellulosic wastes to improve ethanol and biogas production : A review
- 2008
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Ingår i: International Journal of Molecular Sciences. - : Molecular Diversity Preservation International (MDPI) AG.. - 1661-6596 .- 1422-0067. ; 9:9, s. 1621-1651
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Tidskriftsartikel (refereegranskat)abstract
- Lignocelluloses are often a major or sometimes the sole components of different waste streams from various industries, forestry, agriculture and municipalities. Hydrolysis of these materials is the first step for either digestion to biogas (methane) or fermentation to ethanol. However, enzymatic hydrolysis of lignocelluloses with no pretreatment is usually not so effective because of high stability of the materials to enzymatic or bacterial attacks. The present work is dedicated to reviewing the methods that have been studied for pretreatment of lignocellulosic wastes for conversion to ethanol or biogas. Effective parameters in pretreatment of lignocelluloses, such as crystallinity, accessible surface area, and protection by lignin and hemicellulose are described first. Then, several pretreatment methods are discussed and their effects on improvement in ethanol and/or biogas production are described. They include milling, irradiation, microwave, steam explosion, ammonia fiber explosion (AFEX), supercritical CO2 and its explosion, alkaline hydrolysis, liquid hot-water pretreatment, organosolv processes, wet oxidation, ozonolysis, dilute- and concentrated-acid hydrolyses, and biological pretreatments.
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| 2. |
- Bauer, Mikael, et al.
(författare)
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Protein GB1 Folding and Assembly from Structural Elements.
- 2009
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1422-0067. ; 10:4, s. 1552-1566
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Tidskriftsartikel (refereegranskat)abstract
- Folding of the Protein G B1 domain (PGB1) shifts with increasing salt concentration from a cooperative assembly of inherently unstructured subdomains to an assembly of partly pre-folded structures. The salt-dependence of pre-folding contributes to the stability minimum observed at physiological salt conditions. Our conclusions are based on a study in which the reconstitution of PGB1 from two fragments was studied as a function of salt concentrations and temperature using circular dichroism spectroscopy. Salt was found to induce an increase in beta-hairpin structure for the C-terminal fragment (residues 41 - 56), whereas no major salt effect on structure was observed for the isolated N-terminal fragment (residues 1 - 41). In line with the increasing evidence on the interrelation between fragment complementation and stability of the corresponding intact protein, we also find that salt effects on reconstitution can be predicted from salt dependence of the stability of the intact protein. Our data show that our variant (which has the mutations T2Q, N8D, N37D and reconstitutes in a manner similar to the wild type) displays the lowest equilibrium association constant around physiological salt concentration, with higher affinity observed both at lower and higher salt concentration. This corroborates the salt effects on the stability towards denaturation of the intact protein, for which the stability at physiological salt is lower compared to both lower and higher salt concentrations. Hence we conclude that reconstitution reports on molecular factors that govern the native states of proteins.
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| 3. |
- Brueggemann, Dagmar A., et al.
(författare)
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Muscle contraction and force: the importance of an ancillary network, nutrient supply and waste removal
- 2008
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1422-0067. ; 9:8, s. 1472-1488
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Tidskriftsartikel (refereegranskat)abstract
- Muscle contraction studies often focus solely on myofibres and the proteins known to be involved in the processes of sarcomere shortening and cross-bridge cycling, but skeletal muscle also comprises a very elaborate ancillary network of capillaries, which not only play a vital role in terms of nutrient delivery and waste product removal, but are also tethered to surrounding fibres by collagen "wires". This paper therefore addresses aspects of the ancillary network of skeletal muscle at both a microscopic and functional level in order to better understand its role holistically as a considerable contributor to force transfer within muscular tissue.
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| 4. |
- Pourbafrani, M., et al.
(författare)
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Protective Effect of Encapsulation in Fermentation of Limonene-contained Media and Orange Peel Hydrolyzate
- 2007
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Ingår i: International Journal of Molecular Sciences. - : Molecular Diversity Preservation International (MDPI) AG.. - 1661-6596 .- 1422-0067. ; 8:8, s. 777-787
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Tidskriftsartikel (refereegranskat)abstract
- This work deals with application of encapsulation technology to eliminate inhibition of D-limonene in fermentation of orange wastes to ethanol. Orange peel was enzymatically hydrolyzed with cellulase and pectinase. However fermentation of the released sugars in this hydrolyzate by freely suspended S. cerevisiae failed due to inhibition of limonene. On the other hand, encapsulation of S. cerevisiae in alginate membranes was a powerful tool to eliminate inhibition of limonene. The encapsulated cells were able to ferment the orange peel hydrolyzate in 7 h, and produce ethanol with yield 0.44 g/g fermentable sugars. Cultivation of the encapsulated yeast in defined medium was successful, even in the presence of 1.5% (v/v) limonene. The capsules’ membranes were selectively permeable to the sugars and the other nutrients, but not limonene. While 1% (v/v) limonene was present in the culture, its concentration inside the capsules was not more than 0.054% (v/v).
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| 5. |
- Purwadi, R., et al.
(författare)
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A Possible Industrial Solution to Ferment Lignocellulosic Hydrolyzate to Ethanol : Continuous Cultivation with Flocculating Yeast
- 2007
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Ingår i: International Journal of Molecular Sciences. - : Molecular Diversity Preservation International (MDPI) AG.. - 1661-6596 .- 1422-0067. ; 8:9, s. 920-932
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Tidskriftsartikel (refereegranskat)abstract
- Cultivation of toxic lignocellulosic hydrolyzates has been a research topic in recent decades. Although several methods have been proposed, there has been doubt about their industrial applications. The current work deals with a solution to this problem which has a good potential application in industrial scale. A toxic dilute-acid hydrolyzate was continuously cultivated using a high-cell-density flocculating yeast in a single and serial bioreactor which was equipped with a settler to recycle the cells back to the bioreactors. No prior detoxification was necessary to cultivate the hydrolyzates, as the flocks were able to detoxify it in situ. The experiments were successfully carried out at dilution rates up to 0.52 h-1. The cell concentration inside the bioreactors was between 23 and 35 g-DW/L, while this concentration in the effluent of the settlers was 0.320.05 g-DW/L. The ethanol yield of 0.42-0.46 g/g-consumed sugar was achieved, and the residual sugar concentration was less than 6% of the initial fermentable sugar (glucose, galactose and mannose) of 35.2 g/L.
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| 6. |
- Samiotakis, Antonios, et al.
(författare)
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Folding, stability and shape of proteins in crowded environments : experimental and computational approaches
- 2009
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Ingår i: International journal of molecular sciences. - : MDPI AG. - 1422-0067. ; 10:2, s. 572-88
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Tidskriftsartikel (refereegranskat)abstract
- How the crowded environment inside cells affects folding, stability and structures of proteins is a vital question, since most proteins are made and function inside cells. Here we describe how crowded conditions can be created in vitro and in silico and how we have used this to probe effects on protein properties. We have found that folded forms of proteins become more compact in the presence of macromolecular crowding agents; if the protein is aspherical, the shape also changes (extent dictated by native-state stability and chemical conditions). It was also discovered that the shape of the macromolecular crowding agent modulates the folding mechanism of a protein; in addition, the extent of asphericity of the protein itself is an important factor in defining its folding speed.
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| 7. |
- Spijksma, Gerald I., et al.
(författare)
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Modification of Different Zirconium Propoxide Precursors by Diethanolamine. Is There a Shelf Stability Issue for Sol-Gel Applications?
- 2009
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 10, s. 4977-4989
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Tidskriftsartikel (refereegranskat)abstract
- Modification of different zirconium propoxide precursors with H(2)dea was investigated by characterization of the isolated modified species. Upon modification of zirconium n-propoxide and [Zr((OPr)-Pr-n)((OPr)-Pr-i)(3)((PrOH)-Pr-i)](2) with a mol equivalent of H(2)dea the complexes [Zr-2((OPr)-Pr-n)(6)(OCH2CH2)(2)NH](2) (1) and [Zr-2((OPr)-Pr-n)(2)((OPr)-Pr-i)(4)(OCH2CH2)(2)NH](2) (2) were obtained. However, H-1-NMR studies of these tetranuclear compounds showed that these are not time-stable either in solution or solid form. The effect of this time instability on material properties is demonstrated by light scattering and TEM experiments. Modification of zirconium isopropoxide with either or 1 equivalent mol of H(2)dea results in formation of the trinuclear complex, Zr{eta(3)mu(2)-NH(C2H4O)(2)}(3)[Zr((OPr)-Pr-i)(3)](2)(iPrOH)(2) (3) countering a unique nona-coordinated central zirconium atom. This complex 3 is one of the first modified zirconium propoxide precursors shown to be stable in solution for long periods of time. The particle size and morphology of the products of sol-gel synthesis are strongly dependent on the time factor and eventual heat treatment of the precursor solution. Reproducible sol-gel synthesis requires the use of solution stable precursors.
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| 8. |
- Tajsharghi, Homa
(författare)
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Thick and thin filament gene mutations in striated muscle diseases
- 2008
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 9:7, s. 1259-1275
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Forskningsöversikt (refereegranskat)abstract
- The sarcomere is the fundamental unit of cardiac and skeletal muscle contraction. During the last ten years, there has been growing awareness of the etiology of skeletal and cardiac muscle diseases originating in the sarcomere, an important evolving field. Many sarcomeric diseases affect newborn children, i. e. are congenital myopathies. The discovery and characterization of several myopathies caused by mutations in myosin heavy chain genes, coding for the major component of skeletal muscle thick filaments, has led to the introduction of a new entity in the field of neuromuscular disorders: myosin myopathies. Recently, mutations in genes coding for skeletal muscle thin filaments, associated with various clinical features, have been identified. These mutations evoke distinct structural changes within the sarcomeric thin filament. Current knowledge regarding contractile protein dysfunction as it relates to disease pathogenesis has failed to decipher the mechanistic links between mutations identified in sarcomeric proteins and skeletal myopathies, which will no doubt require an integrated physiological approach. The discovery of additional genes associated with myopathies and the elucidation of the molecular mechanisms of pathogenesis will lead to improved and more accurate diagnosis, including prenatally, and to enhanced potential for prognosis, genetic counseling and developing possible treatments for these diseases. The goal of this review is to present recent progress in the identification of gene mutations from each of the major structural components of the sarcomere, the thick and thin filaments, related to skeletal muscle disease. The genetics and clinical manifestations of these disorders will be discussed.
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| 9. |
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