Wettability of Aqueous Rhamnolipids Solutions Produced by Pseudomonas aeruginosa LBI

The wetting behavior of rhamnolipids produced by Pseudomonas aeruginosa LBI strain grown on waste oil substrate and sodium dodecyl sulfate (SDS) on glass, polyethylene terephthalate (PET), poly(vinyl chloride) (PVC), poly(ε-caprolactone) (PCL) and polymer blend (PVC–PCL) was investigated by the measuring contact angle of sessile drops, to determine the wetting characteristics of rhamnolipids. The comparison of the wetting profiles showed that at low SDS and rhamnolipid concentrations, the contact angle increased and when the concentration of the surfactant increased further, the contact angle decreased. The blend surface (PVC–PCL) showed better wettability than the homopolymers themselves and the blend changed the surface hydrophobicity of the polymer, making it more hydrophilic. The rhamnolipids produced by the LBI strain exhibited superior wetting abilities than the chemical surfactant SDS one. This is the first work that evaluates the wetting properties of rhamnolipids on polymer blends.

Bioturbation-driven release of organic contaminants from Baltic Sea sediments mediated by the invading polychaete Marenzelleria neglecta

Baltic Sea sediments are among the world's most polluted regarding eutrophication and contamination. Eutrophication-induced hypoxia has caused depletion of bioturbating macrofauna in vast areas, producing laminated sediments. We investigated if reoxygenation and colonization by the invading deep-burrowing polychaete Marenzelleria neglecta may cause an augmented contaminant release from Baltic Sea sediments. Intact laminated sediment cores were exposed either to in situ hypoxia, reoxygenation, or reoxygenation combined with bioturbating M. neglecta. The release fluxes of particle-associated (N(Pat)) and dissolved (N(Diss)) PCBs and chlorinated pesticide residues (POPs) were quantified (GC-ECD) after 85 d along with contaminant concentrations in sediment and biota. Lavoisier-based mass transfer coefficients (Kf) were calculated from N(Diss). Sediment contaminant concentrations were high (sigmaPCB7: 42-52 ng g(sediment)(-1) dw) due to emissions from Stockholm. N(Diss) always exceeded N(Part) by an order of magnitude. Bioturbation enhanced N(Diss) and Kf from hypoxic sediments 0.7-3 times while reoxygenation alone had no significant effect. M. neglecta accumulated low amounts of contaminants but significantly stimulated aquatic release of bioavailable sequestered contaminants. Bioturbation should be included in aquatic contaminant fate models. We advise to consider quiescent pollutant sources and possible ecological shifts when aiming to restore eutrophicated aquatic environments.     

Race to the top in traffic calming

We study the competition of two suburbs facing transit traffic flows. The suburbs are substitutes for transit traffic. In the absence of toll measures, the symmetric Nash equilibrium with two local governments leads to a race to the top in traffic calming measures that increases the cost of travel. The Nash equilibrium is compared to two types of centralized decisions: the symmetric solution and the asymmetric solution. The asymmetric solution that concentrates all transit traffic in one suburb is better but can only be realized if the authority over the local roads is transferred to the central authority.     

Controlling the abruptness of axial heterojunctions in III-V nanowires: beyond the reservoir effect

Heterostructure nanowires have many potential applications due to the avoidance of interface defects by lateral strain relaxation. However, most heterostructure semiconductor nanowires suffer from persistent interface compositional grading, normally attributed to the dissolution of growth species in the common alloy seed particles. Although progress has been made for some material systems, most binary material combinations remain problematic due to the interaction of growth species in the alloy. In this work we investigate the formation of interfaces in InAs-GaAs heterostructures experimentally and theoretically and demonstrate a technique to attain substantially sharper interfaces. We show that by pulsing the Ga source during heterojunction formation, In is pushed out before GaAs growth initiates, greatly reducing In carry-over. This procedure will be directly applicable to any nanowire system with finite nonideal solubility of growth species in the alloy seed particle and greatly improve the applicability of these structures in future devices.     

Evaluating the environmental impacts of recycling wind turbines

Wind power is one of the fastest growing renewable energy sources. The wind turbines have an expected design lifetime in the range of 20 to 25 years after which decommissioning is expected. The trend in the wind turbine industry is that the turbines increase in size—especially when considering offshore wind turbines in the 7 to 8 MW size range. Life cycle assessments show that the materials used for manufacturing the turbines accounts for 70 to 80% of the environmental impact, so ensuring optimal recycling at the end‐of‐service‐life is of economic and environmental interest and in line with the principles of transitioning towards a circular economy. The decommissioning and recycling process is analysed in this paper, with special considerations given to the environmental aspects of a theoretical 100% recyclability scenario. This includes cradle‐to‐gate life‐cycle inventory analysis of the materials, embedded energy, and CO₂‐equivalent emissions. The findings show that established recycling methods are present for most of the materials and that recycling of a 60 MW wind park at end‐of‐service‐life provides environmental benefits as well as lowering the natural resource use and securing resources for use in the future. The saved energy is estimated to approximately 81 TJ. The reduction in emissions related to the recycling of wind turbine material totals approximately 7351 ton CO₂.     

The mechanical behaviour of cerium-modified alpha-beta brass at high temperatures

The mechanical behaviour of a fine-grained Cu-38.6% Zn alloy with and without 0.07% Ce was studied at 475 to 675° C. It was found that the addition of Ce lowered the flow stress by a factor of three. It was concluded that this arose from a decrease in the volume fraction of the harder alpha phase due to the reduced zinc solubility.     

Age-dependent changes in the nervous and endocrine control of the thymus

The immune system, especially the thymus, undergoes age-related modifications leading to structural and functional changes in the lymphoid organs and immunocompetent cells. Nevertheless, the consequences of thymic involution in the peripheral pool of T-cells are still a matter of controversy. The control of the thymic function is very complex and involves intrathymic signals, the autonomic nervous system, and the endocrine system. Both thymocytes and thymic stromal cells express receptors for a wide range of hormones, as well as for neurotransmitters and neuropeptides, thus affecting thymocytes maturation. This review summarizes the age-dependent variations in the extrathymic components of the thymic microenvironment, i.e., vegetative nerves and hormones, and the possible effects of those changes in the immune function.