Ultramafic vegetation and soils in the circumboreal region of the Northern Hemisphere

The paper summarizes literature on climate, soil chemistry, vegetation and metal accumulation by plants found on ultramafic substrata in the circumboreal zone (sensu Takhtajan, Floristic regions of the world, 1986) of the Northern Hemisphere. We present a list of 50 endemic species and 18 ecotypes obligate to ultramafic soils from the circumboreal region of Holarctic, as well as 30 and 2 species of Ni and Zn hyperaccumulators, respectively. The number of both endemics and hyperaccumulators are markedly lower compared to that of the Mediterranean and tropical regions. The diversity of plant communities on ultramafics soils of the circumboral region is also described. The underlying causes for the differences of ultramafic flora between arctic, cold, cool temperate and Mediterranean and tropical regions are also discussed. © 2018, The Ecological Society of Japan

Practice of reinforced embankment on hard foundation - a case study of Phitsanulok, Thailand

A full scale reinforced test embankment was designed and constructed by Department of Highways (DOH) on hard foundation (i.e. Soil stratum containing relatively stiff to very stiff clay) in Phitsanulok Province, Thailand. Two types of reinforcements were used. One side, called reinforced steep slope (RSS) with folded polymer facing at an angle of 70 degrees from the horizontal, was reinforced with polymeric reinforcements consisting of polyester (PET), polypropylene (PP) and high density polyethelene (HDPE). The other side, called mechanically stabilized earth wall (MSEW) with vertical segmental concrete facing, was reinforced with metallic reinforcement consisting of metallic strips (MS) and steel wire grids (SWG). The behaviour of the RSS and MSEW slopes were observed, back-analysed by sensitivity analysis and compared with the predictions from FEM PLAXIS 3D simulations. As expected the vertical settlements were very small for the hard foundation. The corresponding lateral movements from the RSS side were much larger than the MSEW side due to the higher stiffnesses of the former than the later. The magnitudes of the reinforcing material stiffnesses decrease in the following order: metallic strips (MS), steel wire grids (SWG), polypropylene (PP) high density polyethelene (HDPE) and polyester (PET). The polymeric reinforcements have comparable ultimate tensile strengths at 100 KN/m. The predictions from the FEM PLAXIS 3D simulations were in good agreement with the field measurements in terms of vertical and lateral deformations as well as strains in the reinforcements

Surface Derivatization Strategy for Combinatorial Analysis of Cell Response to Mixtures of Protein Domains

We report a robust strategy for conjugating mixtures of two or more protein domains to non-fouling polyurethane surfaces. In our strategy, the carbamate groups of polyurethane are reacted with zirconium alkoxide from the vapor phase to give a surface bound oxide that serves as a chemical layer that can be used to bond organics to the polymer substrate. An hydroxyalkylphosphonate monolayer was synthesized on this layer, which was then used to covalently bind primary amine groups in protein domains using chloroformate-derived cross-linking. The effectiveness of this synthesis strategy was gauged by using an ELISA to measure competitive, covalent bonding of cell-binding (III(9–10)) and fibronectin-binding (III(1–2)) domains of the cell adhesion protein fibronectin. Cell adhesion, spreading, and fibronectin matrix assembly were examined on surfaces conjugated with single domains, a 1:1 surface mixture of III(1–2) and III(9–10), and a recombinant protein “duplex” containing both domains in one fusion protein. The mixture performed as well or better than the other surfaces in these assays. Our surface activation strategy is amenable to a wide range of polymer substrates and free amino group-containing protein fragments. As such, this technique may be used to create biologically specific materials through the immobilization of specific protein groups or mixtures thereof on a substrate surface