Aging processes and characterization methods for historical bookbinding leather

Content: The original substance of a book binding provides information about the place of origin, storage and user history of the book, why the preservation of this material in its original form is of crucial importance for research in the field of bookbinding. In a current research project in cooperation with FILK Freiberg, a newly sustainable treatment for historical aged leather book covers will be developed. The aim is to introduce a long-term mild care agent to boost leather flexibility, which will remain in the structure and to stabilize the pH value at the optimal level with the buffer introduced in the form of deacidification agent. Preliminary research showed, that ageing processes of vegetable tanned calf leather, which has been mainly used for leather book bindings in the past centuries, haven’t been fully explored yet. Further, essential characterization methods like the determination of the acid content and methods for accelerated aging tests are not yet defined for leather. For a systematic development and evaluation of the newly treatment, the project had to be focused on these topics first. Oxidation and acid-catalyzed hydrolysis have an enormous impact on the state of the leather. Both take place simultaneously and affect each other. It could be shown that the damage by acid hydrolysis is much more dominant than the damage by oxidation. Since oxidation plays only a minor role and can be slowed down only preventively by storage conditions, the project focused on the hydrolysis as the significant degradation mechanism. The aim of accelerated ageing was to reproduce as precisely as possible observed and identified degradation mechanisms in the natural aged leather. Therefore, a two-step aging process has been developed. The first stage is to introduce the acid into the material that is to be used to simulate the acid catalyzed hydrolytic degradation. The second step is to verify the effectiveness of the newly developed care products by comparing treated and untreated leathers at this stage of aging. The aging was evaluated by optical / haptic tests, shrinking temperature, mechanical properties, hot water solubility, pH value and differential number. Regarding the leather characterization, the determination of the exact amount of acid introduced by the artificial aging is of great importance for the development of the aging method as well as for the pH adjustment of the leather. For the method development, an acid-base titration was selected, which allows quantitative results of the acid content in the examined material. The developed method is easy to carry out and allows the measurements of different sample quantities (0,1 g - 1,0 g). Take-Away: - acid-catalyzed hydrolysis is the dominant degradation mechanism, oxidation plays a minor role - acid-base tritration allows quantitative results of the acid content in the examined material - development of an accelerated ageing metho

Opaque voxel-based tree models for virtual laser scanning in forestry applications

Virtual laser scanning (VLS), the simulation of laser scanning in a computer environment, is a useful tool for field campaign planning, acquisition optimisation, and development and sensitivity analyses of algorithms in various disciplines including forestry research. One key to meaningful VLS is a suitable 3D representation of the objects of interest. For VLS of forests, the way trees are constructed influences both the performance and the realism of the simulations. In this contribution, we analyse how well VLS can reproduce scans of individual trees in a forest. Specifically, we examine how different voxel sizes used to create a virtual forest affect point cloud metrics (e.g., height percentiles) and tree metrics (e.g., tree height and crown base height) derived from simulated point clouds. The level of detail in the voxelisation is dependent on the voxel size, which influences the number of voxel cells of the model. A smaller voxel size (i.e., more voxels) increases the computational cost of laser scanning simulations but allows for more detail in the object representation. We present a method that decouples voxel grid resolution from final voxel cube size by scaling voxels to smaller cubes, whose surface area is proportional to estimated normalised local plant area density. Voxel models are created from terrestrial laser scanning point clouds and then virtually scanned in one airborne and one UAV-borne simulation scenario. Using a comprehensive dataset of spatially overlapping terrestrial, UAV-borne and airborne laser scanning field data, we compare metrics derived from simulated point clouds and from real reference point clouds. Compared to voxel cubes of fixed size with the same base grid size, using scaled voxels greatly improves the agreement of simulated and real point cloud metrics and tree metrics. This can be largely attributed to reduced artificial occlusion effects. The scaled voxels better represent gaps in the canopy, allowing for higher and more realistic crown penetration. Similarly high accuracy in the derived metrics can be achieved using regular fixed-sized voxel models with notably finer resolution, e.g., 0.02 m. But this can pose a computational limitation for running simulations over large forest plots due to the ca. 50 times higher number of filled voxels. We conclude that opaque scaled voxel models enable realistic laser scanning simulations in forests and avoid the high computational cost of small fixed-sized voxels

Crystallization and preliminary X-ray analysis of the 9 kDa protein of the mouse signal recognition particle and the selenomethionyl-SRP9

AbstractTwo different crystal forms of the 9 kDa protein of the signal recognition particle (SRP9) have been prepared by the hanging drop vapor diffusion technique using 28% (w/v) PEG8000 or 28% saturated ammonium sulphate as precipitant. The crystals are hexagonal bipyramids with average dimensions of 0.2 × 0.1 × 0.1 mm3 and they diffract to a resolution of 2.3 Å. They belong to the space groups P6222/P6422 or P3121/P3221 with cell dimensions a = b = 63.0 Å, and c = 111.5 Å. Crystals have also been grown from the selenomethionyl protein and multiwavelength data sets have been collected

Keep Them Engaged! Investigating the Effects of Self-centered Social Media Communication Style on User Engagement in 12 European Countries

On Facebook, patterns of user engagement largely shape what types of political contents citizens can see on the platform. Higher engagement leads to higher visibility. Therefore, one of the major goals of political actors' Facebook communication is to produce content with the potential to provoke user engagement, and thereby increase their own visibility. This study introduces the concept of self-centered social media communication style which focuses on 'salient' and 'owned' issues with populist and negative appeals and investigates how user engagement is related to its main elements. We also explore how users' receptivity to these content-related factors is shaped by country context. More specifically, we hypothesize that users are more likely to react, comment on and share posts focusing on salient topics or issues 'owned' by parties rather than more permanent policy issues, and posts including populist appeals and negativity. Further, we test how these effects are moderated by geographical regions and the level of party system polarization. We manually coded 9,703 Facebook posts of 68 parties from 12 European countries in the context of the 2019 European elections. Our findings show that users are more likely to engage with immigration-related, domestic, populist and negative posts, but react less to posts dealing with environmental or economic issues. While issue ownership does not play a significant role for user engagement, country context plays a minor role. However, some populist appeals are more effective in more polarized countries