Opale: Photonische Kristalle

Opals are self‐assembled fcc‐packed colloidal crystals with sphere diameters in the nanometer and submicrometer region. The periodic dielectric structure leads to the opening of photonic band gaps that suppress the propagation of light with wavelengths at the lattice constant scale. This explains e.g. the opals' brilliant color impression. Synthetic opals can be prepared from polymer or metaloxide spheres in a bottom‐up approach that allows for chemical functionalization and processing. Also, they can be used as templates to fabricate inverted structures. Fields of application reach from optical chips, color displays and effect pigments to biosensors.     

Solvent Effects on Acrylate kp in Organic Media?—A Systematic PLP–SEC Study

The Arrhenius parameters of the propagation rate coefficient, k_p, are determined employing high‐frequency pulsed laser polymerization–size exclusion chromatography (PLP–SEC) for the homologous series of five linear alkyl acrylates (i.e., methyl acrylate (MA), butyl acrylate (BA), dodecyl acrylate (DA), stearyl acrylate (SA), and behenyl acrylate (BeA)) in 1 m solution in butyl acetate (BuAc) as well as in toluene. The comparison of the obtained k_p values with the literature known values for bulk demonstrates that no significant solvent influence neither in BuAc nor in toluene on the propagation reaction compared to bulk is detectable. Concomitantly, the k_p values in toluene and in BuAc solution display a similar increase with increasing number of C‐atoms in the ester side chain as was previously reported for the bulk systems. These findings are in clear contrast to earlier studies, which report a decrease of k_p with increasing ester side chain length in toluene. The additional investigation of the longest and shortest ester side chain acrylate (i.e., BeA and MA) over the entire experimentally available concentration range at one temperature (i.e., 50 °C) does not reveal any general concentration dependence and all observed differences in the k_p are within the experimental error.

     

Solvent Effects on kp in Organic Media?: Statement to the Response

A recent response on a publication from our team investigating solvent effects on propagation rate coefficients is commented. Among other issues, we point to the fact that the response interprets only a subset of the data provided in our original contribution.

     

Chip-calorimetric monitoring of biofilm eradication with bacteriophages reveals an unexpected infection-related heat profile

Bacteriophages or phage-derived biological structures are a promising alternative to the application of antibiotics to eradicate biofilms. These countermeasures are highly cell specific. For a better understanding of the sequence of the underlying processes (attachment, infection, multiplication, phage release), for optimization of phage applications, or simply for screening of suitable phages or phage-derived enzymes, real-time monitoring devices are urgently required. Calorimetry is promising because it is non-invasive and quantitatively connected to the metabolic fluxes. Chip-calorimetry provides real-time information about biofilm eradication by phages. This was confirmed by comparison with reference analyses (i.e., confocal laser scanning microscopy, colony plate counts, or phage titre determination). Furthermore, chip-calorimetry provides additional information which was not captured by the reference methods such as the enhanced cell-specific heat production caused by the infection process and a residual activity of seemingly persistent bacteria.