Real‐Time NMR Spectroscopy for Studying Metabolism

Current metabolomics approaches utilize cellular metabolite extracts, are destructive, and require high cell numbers. We introduce here an approach that enables the monitoring of cellular metabolism at lower cell numbers by observing the consumption/production of different metabolites over several kinetic data points of up to 48 hours. Our approach does not influence cellular viability, as we optimized the cellular matrix in comparison to other materials used in a variety of in‐cell NMR spectroscopy experiments. We are able to monitor real‐time metabolism of primary patient cells, which are extremely sensitive to external stress. Measurements are set up in an interleaved manner with short acquisition times (approximately 7 minutes per sample), which allows the monitoring of up to 15 patient samples simultaneously. Further, we implemented our approach for performing tracer‐based assays. Our approach will be important not only in the metabolomics fields, but also in individualized diagnostics.     

Sustainable Peptide Synthesis Enabled by a Transient Protecting Group

The growing interest in synthetic peptides has prompted the development of viable methods for their sustainable production. Currently, large amounts of toxic solvents are required for peptide assembly from protected building blocks, and switching to water as a reaction medium remains a major hurdle in peptide chemistry. We report an aqueous solid‐phase peptide synthesis strategy that is based on a water‐compatible 2,7‐disulfo‐9‐fluorenylmethoxycarbonyl (Smoc) protecting group. This approach enables peptide assembly under aqueous conditions, real‐time monitoring of building block coupling, and efficient postsynthetic purification. The procedure for the synthesis of all natural and several non‐natural Smoc‐protected amino acids is described, as well as the assembly of 22 peptide sequences and the fundamental issues of SPPS, including the protecting group strategy, coupling and cleavage efficiency, stability under aqueous conditions, and crucial side reactions.     

Loop calculations for the non-commutative U ⋆(1) gauge field model with oscillator term

The European Physical Journal C - Motivated by the success of the non-commutative scalar Grosse–Wulkenhaar model, a non-commutative U ⋆(1) gauge field theory including an...     

Synthesis of Structurally Complex Silicon Frameworks through the First Sila-Aldol Reaction

Herein, we report on the first sila-aldol reaction, which emphasizes the tight connection between silicon and carbon chemistry. This novel synthetic method provides straightforward access to 2-oxahexasilabicyclo[3.2.1]octan-8-ide, a structurally complex silicon framework, in quantitative yield. Its structure was confirmed by NMR spectroscopy and X-ray crystallography, and it displays a distinctive charge-transfer transition. The complete mechanism of this highly selective rearrangement cascade is outlined and supported by density functional theory (DFT) calculations, which highlight the thermodynamic driving force and the low activation barriers of this powerful silicon–carbon bond-forming strategy.     

Nanosized aerosols from consumer sprays: experimental analysis and exposure modeling for four commercial products

Consumer spray products are already on the market in the cosmetics and household sector, which suggest by their label that they contain engineered nanoparticles (ENP). Sprays are considered critical for human health, because the lungs represent a major route for the uptake of ENP into the human body. To contribute to the exposure assessment of ENP in consumer spray products, we analyzed ENP in four commercially available sprays: one antiperspirant, two shoe impregnation sprays, and one plant-strengthening agent. The spray dispersions were analyzed by inductively coupled plasma mass spectrometry (ICPMS) and (scanning-) transmission electron microscopy ((S)TEM). Aerosols were generated by using the original vessels, and analyzed by scanning mobility particle sizer (SMPS) and (S)TEM. On the basis of SMPS results, the nanosized aerosol depositing in the respiratory tract was modeled for female and male consumers. The derived exposure levels reflect a single spray application. We identified ENP in the dispersions of two products (shoe impregnation and plant spray). Nanosized aerosols were observed in three products that contained propellant gas. The aerosol number concentration increased linearly with the sprayed amount, with the highest concentration resulting from the antiperspirant. Modeled aerosol exposure levels were in the range of 10¹⁰ nanosized aerosol components per person and application event for the antiperspirant and the impregnation sprays, with the largest fraction of nanosized aerosol depositing in the alveolar region. Negligible exposure from the application of the plant spray (pump spray) was observed.     

Combined use of small-angle neutron scattering and atom probe tomography for the analysis of precipitates in a Fe-15 m% Co-25 m% Mo alloy

Atom probe tomography (APT) measurements were conducted to analyze nm-sized precipitates in a Fe-25 m% Co-15 m% Mo model alloy. Calculation of isoconcentration surfaces and application of cluster-search algorithms yielded the chemical compositions of matrix and precipitates. Small-angle neutron scattering (SANS) was performed in order to calculate the ratio of magnetic to nuclear scattering. This so-called A-ratio was compared with values calculated from the chemical information derived from the atom probe data. For this, the magnetism of the precipitates has to be taken into account. Ab-initio studies have been carried out to determine the magnetic moment of the precipitate phase. The results show that the extremely fine precipitates are ferromagnetic and exhibit near-equilibrium composition. In the very early stage of decomposition, however, the composition is different from near-equilibrium. The influences of the magnetism of the precipitates as well as of artifacts from atom probe measurements on the obtained results are discussed.