Oil spill fluorosensing lidar for inclined onshore or shipboard operation

An oil spill detection fluorosensing lidar for onshore or shipboard operation is described. Some difficulties for its operation arise from the inclined path of rays. This is due to the increased reflection of the laser beam at the air-water interface, the decreased fluorescence signal, and the increased background light when compared with other instruments having a close-to-nadir measuring geometry. The analysis of these problems shows that they significantly reduce the detection distance in the presence of a flat water surface. However, waves on the water surface weaken the influence of the laser beam reflections but at the same time cause a variable fluorescence signal, which makes specific signal processing necessary for increased detection ranges. A fluorescence data processing method is proposed that efficiently eliminates the background water column fluorescence from signals such as yellow substance. This enables oil fluorescence to be distinguished from variable natural water fluorescence.     

The humus balance model (HU-MOD): a simple tool for the assessment of management change impact on soil organic matter levels in arable soils

With this paper we present a simple model for the assessment of management impact in arable farming systems on soil organic matter (SOM) levels. The humus balance model (HU-MOD) is designed for application by farmers and extension workers in practice as a tool for management support. To enable practice applicability, HU-MOD bypasses the need for data on soil parameters and can be run with simple management data. HU-MOD is based on a simplified model on carbon and nitrogen pools and fluxes in the soil–plant system. The model proved to be an applicable simple tool for the comparison of management systems in arable farming with regard to the impact on SOM levels. Even though an absolute quantification of SOM level changes is not possible due to the methodical approach bypassing the need for any data on soil parameters, the model may be used to assess a positive or negative impact of a management system or management period compared to a reference and thus may be used to assess the impact of management changes, or to analyse a specific impact for different management periods on a defined spatial unit.     

Microencapsulation of Alkaline Salt Hydrate Melts for Phase Change Applications by Surface Thiol‐Michael Addition Polymerization

The microencapsulation of alkaline salt hydrates suitable as inorganic phase change materials (PCMs) via surface Michael‐type addition polymerization of thiols and acrylates is reported. The encapsulation performance depending on the resins' acrylate‐to‐thiol ratio and monomer functionality is investigated, and the best encapsulation performance is found for resin compositions with considerable acrylate excess ratios. The step‐growth nature of the reaction can be substantiated via comparative bulk polymerizations. A multistage encapsulation mechanism is proposed in order to explain the different dependencies on the acrylate to thiol ratio observed in PCM encapsulations in comparison to bulk polymerizations.

     

Mechanism and substrate specificity of tRNA-guanine transglycosylases (TGTs): tRNA-modifying enzymes from the three different kingdoms of life share a common catalytic mechanism

Transfer RNA-guanine transglycosylases (TGTs) are evolutionarily ancient enzymes, present in all kingdoms of life, catalyzing guanine exchange within their cognate tRNAs by modified 7-deazaguanine bases. Although distinct bases are incorporated into tRNA at different positions in a kingdom-specific manner, the catalytic subunits of TGTs are structurally well conserved. This review provides insight into the sequential steps along the reaction pathway, substrate specificity, and conformational adaptions of the binding pockets by comparison of TGT crystal structures in complex with RNA substrates of a eubacterial and an archaebacterial species. Substrate-binding modes indicate an evolutionarily conserved base-exchange mechanism with a conserved aspartate serving as a nucleophile through covalent binding to C1' of the guanosine ribose moiety in an intermediate state. A second conserved aspartate seems to control the spatial rearrangement of the ribose ring along the reaction pathway and supposedly operates as a general acid/base. Water molecules inside the binding pocket accommodating interaction sites subsequently occupied by polar atoms of substrates help to elucidate substrate-recognition and substrate-specificity features. This emphasizes the role of water molecules as general probes to map binding-site properties for structure-based drug design. Additionally, substrate-bound crystal structures allow the extraction of valuable information about the classification of the TGT superfamily into a subdivision of presumably homologous superfamilies adopting the triose-phosphate isomerase type barrel fold with a standard phosphate-binding motif.