<scp>ReSurveyEurope</scp>: A database of resurveyed vegetation plots in Europe

AbstractAimsWe introduce ReSurveyEurope — a new data source of resurveyed vegetation plots in Europe, compiled by a collaborative network of vegetation scientists. We describe the scope of this initiative, provide an overview of currently available data, governance, data contribution rules, and accessibility. In addition, we outline further steps, including potential research questions.ResultsReSurveyEurope includes resurveyed vegetation plots from all habitats. Version 1.0 of ReSurveyEurope contains 283,135 observations (i.e., individual surveys of each plot) from 79,190 plots sampled in 449 independent resurvey projects. Of these, 62,139 (78%) are permanent plots, that is, marked in situ, or located with GPS, which allow for high spatial accuracy in resurvey. The remaining 17,051 (22%) plots are from studies in which plots from the initial survey could not be exactly relocated. Four data sets, which together account for 28,470 (36%) plots, provide only presence/absence information on plant species, while the remaining 50,720 (64%) plots contain abundance information (e.g., percentage cover or cover–abundance classes such as variants of the Braun‐Blanquet scale). The oldest plots were sampled in 1911 in the Swiss Alps, while most plots were sampled between 1950 and 2020.ConclusionsReSurveyEurope is a new resource to address a wide range of research questions on fine‐scale changes in European vegetation. The initiative is devoted to an inclusive and transparent governance and data usage approach, based on slightly adapted rules of the well‐established European Vegetation Archive (EVA). ReSurveyEurope data are ready for use, and proposals for analyses of the data set can be submitted at any time to the coordinators. Still, further data contributions are highly welcome.</jats:sec

The influence of mineralization conditions on the effectiveness of enzymatic mineralization of hydrogels

Polysaccharide hydrogels are widely used in food industry and medicine. Gellan gum (GG) recently gained a lot of attention as a promising material for tissue regeneration proposes due to its excellent biocompatibility and similarity to natural extracellular matrix. However, in unmineralized form it is not suitable for bone tissue engineering because of weak mechanical properties. Enzymatic mineralization (e.g. using alkaline phosphatase – ALP) is one of the methods of calcifying of hydrogels and it resembles natural processes occurring during bone healing. The aim of this research was to investigate mineralization of hydrogels and to improve properties of gellan gum scaffolds by adjusting processing conditions. Since ALP does not form with GG covalent bonds, during incubation in mineralization medium (solution of calcium glycerophosphate - CaGP) it is diffusing from the samples. Therefore, mineralization effectiveness depends on the interplay between incoming CaGP and outgoing ALP molecules. We hypothesize that better CaGP availability, especially in the first hours of incubation, can result in more effective and homogenous precipitation of calcium phosphates (CaP) in GG samples. To this end, samples with different GG and ALP concentration were subjected to two different mineralization regimes (more and less frequent CaGP exchanges). We proved that better CaGP availability (more frequent CaGP exchange) resulted in better mechanical properties (Young’s modulus) and more effective mineral formation (higher dry mass percentage) of the samples compared to the same samples mineralized with lower accessibility of CaGP. This may be related to the fact, that in presence of fresh organic substrates, more CaP are formed in the outer parts of the samples at the beginning of the process, that limit ALP diffusion and allow more uniform mineralization

The influence of sintering conditions on microstructure and mechanical properties of titanium dioxide scaffolds for the treatment of bone tissue defects

In this study the attempts to improve mechanical properties of highly-porous titanium dioxide scaffolds produced by polymer sponge replication method were investigated. Particularly the effect of two-step sintering at different temperatures on microstructure and mechanical properties (compression test) of the scaffolds were analysed. To this end microcomputed tomography and scanning electron microscopy were used as analytical methods. Our experiments showed that the most appropriate conditions of manufacturing were when the scaffolds were heat-treated at 1500 °C for 1 h followed by sintering at 1200 °C for 20 h. Such scaffolds exhibited the highest compressive strength which was correlated with the highest linear density and the lowest size of grains. Moreover, grain size distribution was narrower with predominating fraction of fine grains 10–20 μm in size. Smaller grains and higher linear density suggested that in this case densification process prevailed over undesirable process of grain coarsening, which finally resulted in improved mechanical properties of the scaffolds

The effect of titanium dioxide addition on physical and biological properties of Na2O-B2O3-P2O5 and CaO-Na2O-P2O5 glasses

Two types of phosphate glasses 50Na2O-20B2O3-30P2O5 (NBP) and 30CaO-20Na2O-50P2O5 (CNP) with different content of TiO2 (0, 3 and 5 mol%) have been prepared by melt-quenching process. TiO2 was added to increase glass network stability. Physical properties of glasses were investigated by density measurements, differential scanning calorimetry and degradation in phosphate buffered saline (PBS). Biological performance of glasses in a direct contact with osteoblast-like MG-63 cells was analysed with the use of resazurin test and live-dead staining. The results show that TiO2 addition increased density, glass transition temperature (Tg) and melting temperature (Tm) of both types of glasses. In the case of NBP glasses presence of TiO2 resulted in their fast degradation in PBS and acidification of cell culture medium. As a consequence such glasses did not support cell adhesion and growth, but they can be considered for e.g. drug delivery systems. On the other hand addition of TiO2 to CNP glasses resulted in enhanced cell adhesion and viability. Particularly positive results were found for CNP glass containing 5% TiO2, so it can be a good candidate as a scaffold material for bone tissue engineering