Frustrated Lewis pairs (FLPs) have a great potential for activation of small molecules. Most known FLP systems are based on boron or aluminum atoms as acid functions, few on zinc, and only two on boron-isoelectronic silicenium cation systems. The first FLP system based on a neutral silane, (C2F5)3SiCH2P(tBu)2 (1), was prepared from (C2F5)3SiCl with C2F5 groups of very high electronegativity and LiCH2P(tBu)2. 1 is capable of cleaving hydrogen, and adds CO2 and SO2. Hydrogen splitting was confirmed by H/D scrambling reactions. The structures of 1, its CO2 and SO2 adducts, and a decomposition product with CO2 were elucidated by X-ray diffraction.

[1] In marine sedimentary environments, microbial methanotrophy represents an important sink for methane before it leaves the seafloor and enters the water column. Using benthic observatories in conjunction with numerical modeling of pore water gradients, we investigated seabed methane emission rates at cold seep sites with underlying gas hydrates at Hydrate Ridge, Cascadia margin. Measurements were conducted at three characteristic sites which have variable fluid flow and sulfide flux and sustain distinct chemosynthetic communities. In sediments covered with microbial mats of Beggiatoa, seabed methane efflux ranges from 1.9 to 11.5 mmol m À2 d À1 . At these sites of relatively high advective flow, total oxygen uptake was very fast, yielding rates of up to 53.4 mmol m À2 d À1 . In sediments populated by colonies with clams of the genus Calyptogena and characterized by low advective flow, seabed methane emission was 0.6 mmol m À2 d À1 , whereas average total oxygen uptake amounted to only 3.7 mmol m À2 d À1 . The efficiency of methane consumption at microbial mat and clam field sites was 66 and 83%, respectively. Our measurements indicate a high potential capacity of aerobic methane oxidation in the benthic boundary layer. This layer potentially restrains seabed methane emission when anaerobic methane oxidation in the sediment becomes saturated or when methane is bypassing the sediment matrix along fractures and channels.

The main goal of this study was to test whether feedback from a lecturer and tutor on an initial reflective journal entry fosters reflection quality in a subsequent journal entry and reflection skills in student teachers. To address these questions, we, a team of educators and psychologists, conducted a field experiment during the practical semester. Student teachers ( N = 54; 40 female) wrote two reflective journals about their own classroom teachings on an online-platform and were randomly assigned to one of two conditions: (a) reflective journaling with feedback (experimental condition, n = 27) or (b) reflective journaling without feedback (control condition, n = 27). Feedback in reflective journaling fostered reflection quality in the subsequent journal entry and conceptual knowledge about reflection. These findings indicate that feedback in reflective journal-keeping exerts a powerful influence in fostering reflection in student teachers during their practical semester.

New geminally bonded intramolecular donor-acceptor systems, CpLnCHPR (Ln = Y, Ho, Er, R = CHMe, CMe), were prepared by salt elimination reactions between the dicyclopentadienyl-element chlorides (CpLnCl, Ln = Y, Ho, Er) and diorganylphosphinomethanides (RPCHLi; R = CHMe, CMe). These compounds, 1-6, were characterized by elemental analyses, mass spectrometry and X-ray diffraction experiments and the yttrium species additionally by NMR spectroscopy. In the solid state the molecular structures differ from each other, depending on the steric demand of the phosphorus substituents. For all iso-Pr-substituted compounds, dimers [CpLnCHP(CHMe)] with six-membered Ln-C-P-Ln-C-P rings in a chair-like conformation were observed. The sterically more demanding tert-butyl groups prevent dimerization but instead lead to species that undergo complexation of LiCl units by two monomers: [CpLnCHP(CMe)·LiCl]. The solution NMR data for the yttrium compounds are consistent with the solid-state structures. Conversion with phenylacetylene afforded heteroleptic cyclobutane-like alkynyl-rare-earth metal complexes [CpLn(μ-C[triple bond, length as m-dash]CPh)] [Ln = Y (7), Ho (8), Er (9)]. Treatment of compounds 1-6 with 1,8-diethynylanthracene led to single metalation and dimerization and products with similar structural motifs as observed for complexes 7-9. Reactions with dihydrogen and carbon dioxide resulted in Y-C bond breaking, yielding CpYH/RPCH and CO insertion products, respectively.

Heat exchangers are often associated with drawbacks like a large pressure drop or a non-uniform flow distribution. Recent research shows that bionic structures can provide possible improvements. We considered a set of such structures that were designed with M. Hermann's FracTherm(A (R)) algorithm. In order to optimize and compare them with conventional heat exchangers, we developed a numerical method to determine their performance. We simulated the flow in the heat exchanger applying a network model and coupled these results with a finite volume method to determine the heat distribution in the heat exchanger