Zucker in Obstpuddingpulver

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Microcionamides A and B, bioactive peptides from the philippine sponge Clathria (Thalysias) abietina

Microcionamides A (1) and B (2) have been isolated from the Philippine marine sponge Clathria (Thalysias) abietina. These new linear peptides are cyclized via a cystine moiety and have their C-terminus blocked by a 2-phenylethylenamine group. Their total structures, including absolute stereochemistry, were determined by a combination of spectral and chemical methods. Compound 1 was shown to slowly isomerize about the C-36/C-37 double bond when stored in DMSO. Microcionamides A (1) and B (2) exhibited significant cytotoxicity against the human breast tumor cells lines MCF-7 and SKBR-3 and displayed inhibitory activity against Mycobacterium tuberculosis H(37)Ra.     

2,2′:3′,2′′‐Terthiophene‐Based all‐Thiophene Dendrons and Dendrimers: Synthesis,Structural Characterization,and Properties

The synthesis of generational dendritic oligothiophenes (DOTs) has been successfully achieved by a divergent/convergent approach that involves halogenation, boronation, and palladium‐catalyzed Suzuki coupling reactions. The key point in the presented synthetic approach is the use of trimethylsilyl (TMS) protecting groups, which allow for the core‐lithiation and subsequent boronation of the dendrons and for the peripheral ipso‐substitution with iodine monochloride or N‐bromosuccimide. In addition, the TMS protecting groups can be completely removed by using tetrabutylammonium fluoride, thus yielding only‐thiophene‐based dendrons and dendrimers. Due to their highly branched structure, all these synthesized DOTs are soluble in organic solvents. Chemical structures were confirmed by NMR spectroscopic, mass spectrometric, and elemental analysis. Concentration‐dependent ¹H NMR spectroscopic investigations revealed that the higher generation compounds tend to aggregate in solution. Such an aggregation behavior was further confirmed by measuring with MALDI‐TOF MS. Both MALDI‐TOF MS and gel‐permeation chromatography (GPC) analyses confirmed the monodispersity of the DOTs. Furthermore, GPC results revealed that these DOT molecules adopt a condensed globular molecular shape. Their optical and electronic properties were also investigated. The results indicated that these DOTs comprise various conjugated α‐oligothiophenes with different chain lengths, which results in the higher generation compounds showing broad and featureless UV/Vis absorption spectra and ill‐defined redox waves.     

In-situ investigations of the curing of a polyester resin

Quasi-isothermal curing of a polyester resin was studied at different catalyst concentrations and temperatures in-situ by ¹H-NMR relaxometry and NIR spectroscopy simultaneously. Sample and probe temperatures were also recorded. An autocatalytic kinetic model, optionally including a diffusion term, was successfully applied to describe and predict the curing kinetics of the polyester resin as a function of temperature and catalyst concentration, although the diffusion effect is relatively weak in the investigated system under the experimental conditions. The corresponding kinetic coefficients and the reaction activation energy were obtained by fitting the models to the data, assuming an Arrhenius relation.     

Antibacterial membranes based on chitosan and quaternary ammonium salts modified nanocrystalline cellulose

Etherification of nanocrystalline cellulose (NCC) with three kinds of quaternary ammonium salts epoxypropyltrimethylammonium chloride, N,N‐dimethyl‐N‐dodecyl‐N‐(1,2‐epoxypropyl) ammonium chloride (DMDEPAC), and N,N‐dimethyl‐N‐octadecyl‐N‐(1,2‐epoxypropyl) ammonium chloride (DMOEPAC) was successfully performed via a nucleophilic addition reaction. The synthesized DMDEPAC and DMOEPAC were characterized by nuclear magnetic resonance. The modified NCC particles, NCC epoxypropyltrimethylammonium chloride, NCC‐DMDEPAC, and NCC‐DMOEPAC, were characterized by energy dispersive spectrometer. Nanocomposite films based on chitosan (CS) containing quaternary ammonium salts modified NCC were prepared with nanoparticle loadings of 5.0, 7.5, and 10.0%, respectively. The effect of nanoparticle content on the tensile strength of composite films was studied. The results indicated that the films with 5.0% nanoparticle loading exhibited the biggest increase in tensile strength. Surface morphology, smoothness, and antibacterial properties of composite films containing 5% modified NCC were also studied. CS/NCC‐DMDEPAC‐5.0 and CS/NCC‐DMOEPAC‐5.0 displayed excellent biocidal abilities against both Gram‐positive Staphylococcus aureus (ATCC 6538) and Gram‐negative Escherichia coli O157:H7 (ATCC 43895). The bio‐based nanocomposite films with increased mechanical strength and excellent antibacterial properties show great potential as food packaging materials. Copyright © 2017 John Wiley & Sons, Ltd.     

Eine schnelle qualitative und quantitative Mikroanalyse von Weichmachern in Kunststoffen mit Hilfe der Gaschromatographie

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Topochemical acetylation of cellulose nanopaper structures for biocomposites: mechanisms for reduced water vapour sorption

Moisture sorption decreases dimensional stability and mechanical properties of polymer matrix biocomposites based on plant fibers. Cellulose nanofiber reinforcement may offer advantages in this respect. Here, wood-based nanofibrillated cellulose (NFC) and bacterial cellulose (BC) nanopaper structures, with different specific surface area (SSA), ranging from 0.03 to 173.3 m²/g, were topochemically acetylated and characterized by ATR-FTIR, XRD, solid-state CP/MAS ¹³C-NMR and moisture sorption studies. Polymer matrix nanocomposites based on NFC were also prepared as demonstrators. The surface degree of substitution (surface-DS) of the acetylated cellulose nanofibers is a key parameter, which increased with increasing SSA. Successful topochemical acetylation was confirmed and significantly reduced the moisture sorption in nanopaper structures, especially at RH = 53 %. BC nanopaper sorbed less moisture than the NFC counterpart, and mechanisms are discussed. Topochemical NFC nanopaper acetylation can be used to prepare moisture-stable nanocellulose biocomposites.