A central concept in molecular bioscience is how structure formation at different length scales is achieved. Here we use spider silk protein as a model to design new recombinant proteins that assemble into fibers. We made proteins with a three-block architecture with folded globular domains at each terminus of a truncated repetitive silk sequence. Aqueous solutions of these engineered proteins undergo liquid–liquid phase separation as an essential pre-assembly step before fibers can form by drawing in air. We show that two different forms of phase separation occur depending on solution conditions, but only one form leads to fiber assembly. Structural variants with one-block or two-block architectures do not lead to fibers. Fibers show strong adhesion to surfaces and self-fusing properties when placed into contact with each other. Our results show a link between protein architecture and phase separation behavior suggesting a general approach for understanding protein assembly from dilute solutions into functional structures.

Verwendung einer Doppelelektrolytzelle aus ZrO2(CaO) mit ThO2(Y2O3)‐Beschichtung zur Untersuchung der Desoxidationsgleichgewichte Fe–O–Ti, Fe–O–Al und Fe–O–Zr bei 1600 °C über EMK‐Messung sowie Probenahme und chemische Analyse. Ermittlung der Sauerstoffaktivitäten in Abhängigkeit vom Gehalt an Titan, Aluminium oder Zirconium in der Eisenschmelze sowie der Gleichgewichtskonstanten und Wirkungsparameter exx. Vergleich der analytisch bestimmten und thermodynamisch berechneten Sauerstoffgehalte.

Abstract:In the pulp and paper industry different types of pulp or fiber fines are generated during the pulping (primary fines, mechanical fines), and/or the refining process (secondary fines). Besides fibers, these cellulosic microparticles are a further component of the paper network. Fines, which are defined as the fraction of pulp that is able to pass through a mesh screen or a perforated plate having a hole diameter of 76 µm, are known to influence the properties of the final paper product. To better understand the effect and properties of this material, fines have to be separated from the pulp and investigated as an independent material. In the present study, fines are isolated from the pulp fraction by means of a laboratory pressure screen. To allow for further processing, the solids content of the produced fines suspension was increased using dissolved air flotation. Morphological properties of different types of fines and other cellulosic microparticles, such as microfibrillated celluloses (MFC) are determined and compared to each other. Furthermore, handsheets are prepared from these materials and properties, such as apparent density, contact angle, modulus of elasticity, and strain are measured giving similar results for the analyzed types of fines in comparison to the tested MFC grades. The analysis of the properties of fiber fines contributes on the one hand to a better understanding of how these materials influences the final paper products, and on the other hand, helps in identifying other potential applications of this material.

Erprobung einer Doppelelektrolytzelle aus ZrO2(CaO) mit ThO2(Y2O3)‐Beschichtung zur Messung geringer Sauerstoffaktivitäten ao zwischen 10−6 und 10−2 in desoxidierten Eisenschmelzen. Untersuchung der Gleichgewichte Fe‐O‐Cr und Fe‐O‐Mn bei 1600 °C durch EMK‐Messung sowie Probenahme und chemische Analyse. Ermittlung der Sauerstoffaktivitäten in Abhängigkeit vom Gehalt an Chrom oder Mangan in der Schmelze sowie der Gleichgewichtskonstanten und Wirkungsparameter. Vergleich der analytisch bestimmten und thermodynamisch berechneten Sauerstoffgehalte der Schmelzen.

Cellulosic materials are highly sensitive towards environmental changes such as temperature and especially towards humidity. Besides morphological changes like swelling and/or shrinking, the mechanical properties of pulp fibres and fibre to fibre joints change as well. The current study sets to elucidate the changes and the extent to which elevated or decreased relative humidity (RH) influences the load bearing capacity of individual hardwood and softwood fibres and joints. The device used for the measurements is a micro bond tester with a custombuilt humidity chamber in which the humidity can be controlled in a range from 25 to 95% RH. Individual fibres and joints have been tested at 30, 50 and 80% RH after equilibration time of 120 min. The breaking load of individual softwood fibres and joints displayed a maximum breaking load at 50% RH, with the values showing a decreasing trend towards higher or lower RH. In case of hardwoods, no change in the breaking load of either individual fibres or fibre to fibre joints has been observed at different RH.