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Viscose (also known as Rayon) filaments are obtained from regenerated cellulose and are used in many different sectors mainly as reinforcement material in tires and other cord applications and in the clothing industry. The incorporation of a phosphor-containing pigment imparts flame-retardancy properties to these fibers, which then can be used as part of personal protection textiles delivering wear comfort. There are no recycling strategies for these materials being brought to landfills or chemically degraded since incineration is difficult because of their flame retardancy. In this study, an enzyme-based strategy for the recovery of glucose and of the phosphor pigment without altering their chemical structures was developed as a circular economy solution. Rayon fibers were completely hydrolyzed by a cellulase preparation while 98% of the glucose (reducing sugar assay and HPLC analysis) and more than 99% of the flame-retardant pigment present in the fibers was recovered. The recovered pigment was analyzed...

Among synthetic thermoplastic fiber materials for reinforcement, high modulus and low shrinkage poly(ethylene terephthalate) (HMLS-PET) became the major carcass material for the low- to medium-end tire segment. Usually cords are coated with a resorcinol–formaldehyde–latex (RFL) dip to achieve acceptable power transmission. However, the low concentration of polar groups on the PET’s surface requires an additional activation with costly and potentially toxic chemicals to create additional nucleophilic groups prior to RFL dipping. Here, a green enzyme based alternative to chemical HMLS-PET activation was investigated. Four different cutinase variants from Thermobifida cellulosilytica were shown to hydrolyze HMLS-PET cords, creating new carboxylic and hydroxyl groups with distinct exoendo-wise selectivity. The highest degree of enzymatic functionalization reached a concentration of 0.51 nmol mm–2 of COOH with a release of 1.35 mM of soluble products after 72 h. The chemical treatment with 1 M NaOH released mo...

This contribution presents an extensive performance evaluation of metakaolin-based geopolymer and calcium aluminate mortars during a long-term field exposure to a wastewater system exhibiting intensive microbially induced acid corrosion (MIAC) conditions. Results were compared to a high-performance OPC concrete, typically used for manhole fabrication. Field conditions were obtained by monitoring relative humidity, temperature, H2S and CO2. Microstructural degradation and elemental distributions within each binder type over time were recorded by electron probe microanalysis, X-ray diffraction and pH-imaging techniques, together with specimen's mass and surface-pH characterization. Microbiome and epifluorescence analyses indicated exposure-time dependent alternating bacterial community structures within the materials. Clear differences regarding bacterial species distribution and biodiversity were observed for the different binder types. Estimated corrosion rates were the lowest (1.4 mm/a) and the highest (13.3 mm/a) for the tested geopolymer formulations, pointing out that only well designed geopolymer materials may provide an improved MIAC resistance.

A sensitive method for quantification of citric, fumaric, malic, malonic, oxalic, trans aconitic, and succinic acid in soil- and root-related samples is presented. The method is based on a novel, fast, and simple esterification procedure and subsequent analysis via liquid chromatography-mass spectrometry. Derivatization comprises in situ generation of HCl, which catalyzes the Fischer esterification with benzyl alcohol. As a key advance, the esterification with the aromate allows reversed-phase separation and improves electrospray ionization efficiency. The method provided procedural detection limits of 1 nM for citric, 47 nM for fumaric, 10 nM for malic, 10 nM for malonic, 16 nM for oxalic, 15 nM for succinic, and 2 nM for aconitic acid utilizing 500 μL of liquid sample. The working range was 3 nM to 10 μM for citric acid, 158 nM to 10 μM for fumaric acid, 34 nM to 10 μM for malic acid, 33 nM to 10 μM for malonic acid, 53 nM to 10 μM for oxalic acid, 48 nM to 10 μM for succinic acid, and 6 nM to 10 μM for aconitic acid. Quantification of the analytes in soil-related samples was performed via external calibration of the entire procedure utilizing (13)C-labeled oxalic and citric acid as internal standards. The robustness of the method was tested with soil extracts and samples from hydroponic experiments. The latter concerned the regulation of phosphorus solubilization via plant root exudation of citric, malic, and oxalic acid.

Microbial Baeyer-Villiger oxidations of representative mesomeric ketones with recombinant Escherichia coli cells expressing two monooxygenases from Brevibacterium were investigated. The two enzymes displayed enantiodivergent biotransformations on an array of structurally diverse substrates, allowing access to some key lactone intermediates in natural compound synthesis.

Enzyme-mediated Baeyer−Villiger oxidations offer a “green chemistry” approach for the production of chiral lactones. Several organisms have been found to catalyze this reaction in the course of their metabolic pathways. A number of flavin-dependent monooxygenases have been characterized, and acceptance of a multitude of non-natural substrates has been found. Such biocatalysts are used in synthetic chemistry either as isolated enzymes in combination with appropriate cofactor recycling systems or as living whole cells, in native or recombinant form, for the production of valuable intermediates. This review gives an overview of the most widely utilized enzymes and the corresponding substrate profiles, together with applications in natural product and bioactive compound synthesis. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

The synthesis of carbo- and heterocyclic aldehydes bearing an ipso-methoxy group is investigated. The synthetic sequence is based on an initial Grignard addition of an olefin to a cyclic ketone followed by methylation of the resulting tertiary alcohol. The terminal olefin serves as precursor for the aldehyde functionality. Oxidation by ozonolysis turned out to depend significantly on the distance of the donor methoxy group. The observed side reactions could be circumvented by applying a one-pot OsO4 mediated diol formation followed by Malaprade oxidation using KIO4. A series of carbo- and heterocyclic precursors were successfully converted to the title products.

We present numerous applications of the recently developed dual-focus fluorescence correlation spectroscopy (2fFCS) to the measurement of translational diffusion of proteins and protein complexes. The method is applied to measuring Ca2+-binding curves of wild-type and mutant of the proteins calmodulin and recoverin. 2fFCS is also capable of quantifying the conformational flexibility of macromolecular complexes, which is exemplified on the peptide binding of the major histocompatibility complex I (MHC I). Furthermore, we extended 2fFCS to measure fluorescence correlation at the nanosecond time scale, allowing also for measuring rotational diffusion. We performed a comparative study of translational and rotational diffusion (and related hydrodynamics size) of proteins, and present results for several globular proteins (BSA, human serum albumin, aldolase, ovalbumin). In all cases, measurements are performed at pico- to nanomolar sample concentrations, and with an accuracy of determining hydrodynamic size of a few percent. For performing 2fFCS measurements, a protein or protein complex needs only unspecific fluorescent labeling which is easily accomplished with commercially available dyes. Thus it is hoped that 2fFCS becomes a widely used and easy to handle technique in biophysical research.References1. Dertinger T.; Loman A.; Ewers B.; Muller C.B.; Kramer B.; Enderlein J., Opt. Expr.16, 2008, 14353-14368.2. Muller C.B.; Loman A.; Pacheco V.; Koberling F.; Willbold D.; Richtering W.; Enderlein J., Eur. Phys. Lett.83, 2008, 46001.3. Dertinger T.; Pacheco V.; von der Hocht I.; Hartmann R.; Gregor I.; Enderlein J., ChemPhysChem8, 2007, 433-443.