A Peptide‐Functionalized Polymer as a Minimal Scaffold Protein To Enhance Cluster Formation in Early T Cell Signal Transduction

In cellular signal transduction, scaffold proteins provide binding sites to organize signaling proteins into supramolecular complexes and act as nodes in the signaling network. Furthermore, multivalent interactions between the scaffold and other signaling proteins contribute to the formation of protein microclusters. Such microclusters are prominent in early T cell signaling. Here, we explored the minimal structural requirement for a scaffold protein by coupling multiple copies of a proline‐rich peptide corresponding to an interaction motif for the SH3 domain of the adaptor protein GADS to an N‐(2‐hydroxypropyl)methacrylamide polymer backbone. When added to GADS‐containing cell lysates, these scaffolds (but not individual peptides) promoted the binding of GADS to peptide microarrays. This can be explained by the cross‐linking of GADS into larger complexes. Furthermore, following import into Jurkat T cell leukemia cells, this synthetic scaffold enhanced the formation of microclusters of signaling proteins.     

Improved oxidation of air pollutants in a non-thermal plasma

The performance of non-thermal plasma (NTP) for the removal of organic air pollutants (especially in low concentrations) is improved by the introduction of ferroelectric and catalytically active materials into the discharge zone of an NTP reactor. Experiments with model systems (various contaminants and packed-bed materials) have shown that such a modification of a homogeneous gas-phase plasma can overcome the most serious restrictions of the NTP technique at its present state of the art: the incomplete total oxidation (i.e. the low selectivity to CO₂) and the energetic inefficiency.

Placing a ferroelectric packed-bed material in the discharge zone was shown to result in a lowering of the energy input required. The main effects of plasma catalysis enabled by the introduction of a catalytically active material were an enhanced conversion of pollutants and a higher CO₂ selectivity. These improvements are based on the presence of short-lived oxidising species in the inner volume of porous catalysts. Additionally, the formation of a reservoir of adsorbed oxidants in the NTP zone could be shown. The combination of both modifications (ferroelectric packed-bed materials and plasma catalysis) is a promising method to support the NTP-initiated oxidation of air pollutants.     

Experimental determination of the effective thermal conductivity of Vacuum Insulation Panels at fire temperatures

In this study, the effective thermal conductivity of a commercial Vacuum Insulation Panel (VIP) at temperatures up to 900 °C is experimentally determined. An experimental setup, based on the Heat Flow Meter Apparatus (HFMA) method, is designed and realized. Two commercially available VIPs (each 20 mm thick) are joined together to form a specimen, which is subjected to fire conditions from one side, while the other side is at ambient conditions. The temperatures on both sides of the specimen and the heat flux on the unexposed side are recorded. The experimental data are coupled with a numerical model, which takes into account the one dimensional steady state heat transfer through the thickness of the specimen and the detailed heat transfer mechanisms for the effective thermal conductivity of the VIP. Gas, solid and radiation conduction mechanisms are considered and their parameters are defined through an optimization technique. The defined optimized values are found to lie between the respective values reported in the literature. The contribution of each heat transfer mechanism to the overall effective thermal conductivity is also discussed. The paper provides a generalized methodology for the estimation of the effective thermal conductivity of VIPs from ambient to fire temperatures. Copyright © 2016 John Wiley & Sons, Ltd.     

Crystallographic structure and morphology of bithiophene-fluorene polymer nanocrystals

Nanocrystals of the polymer poly(9,9-dioctylfluorenyl-co-bithiophene) (F8T2) with a molecular weight of 3.2 kg/mol are grown in a para-xylene solution. The typical morphology of the crystals is needle like with typical widths of 50 nm and lengths of about 200 nm. The crystal structure and morphology are stable up to a temperature of 353 K. The structure solution is obtained by x-ray powder diffraction (XRD) pattern with data modelling by a stochastic global optimization procedure which allows simultaneous indexing and molecular packing determination. Final Rietveld refinement was applied on the most promising crystal structure with a = 1.376 nm, b = 3.105 nm, c = 2.690 nm and ß = 109.5° within the space group C2/c choosing the polymer backbone parallel to the b-axis. The structural motifs of the molecular packing could be identified: aromatic units within a single polymer chain are slightly bent relative to the chain axis, octyl side chains are aligned along the polymer backbone and aromatic units of neighbouring molecules display a strong tendency to stack parallel to each other. XRD results of F8T2 with a molecular weight of 19 kg/mol reveal the same peak positions compared to the 3.2 kg/mol material, showing that both materials crystallise similarly and can be described by the same crystallographic unit cell. The smaller peak intensities together with the broader peak widths, however, show that the ability of crystal formation for the 19 kg/mol material is reduced.     

Generalized Diffusion Tensor Imaging (GDTI): A Method for Characterizing and Imaging Diffusion Anisotropy Caused by Non-Gaussian Diffusion

For non-Gaussian distributed random displacement, which is common in restricted diffusion, a second-order diffusion tensor is incapable of fully characterizing the diffusion process. The insufficiency of a second-order tensor is evident in the limited capability of diffusion tensor imaging (DTI) in resolving multiple fiber orientations within one voxel of human white matter. A generalized diffusion tensor imaging (GDTI) method was recently proposed to solve this problem by generalizing Fick's law to a higher-order partial differential equation (PDE). The relationship between the higher-order tensor coefficients of the PDE and the higher-order cumulants of the random displacement can be derived. The statistical property of the diffusion process was fully characterized via the higher-order tensor coefficients by reconstructing the probability density function (PDF) of the molecular random displacement. Those higher-order tensor coefficients can be measured using conventional diffusion-weighted imaging or spectroscopy techniques. Simulations demonstrated that this method was capable of quantitatively characterizing non-Gaussian diffusion and accurately resolving multiple fiber orientations. It can be shown that this method is consistent with the q-space approach. The second-order approximation of GDTI was shown to be DTI.     

Disruption of foraging by argentine ants,Iridomyrmex humilis (mayr) (hymenoptera: Formicidae), in citrus trees through the use of semiochemicals and related chemicals

Foraging in trees by the Argentine ant,Iridomyrmex humilis (Mayr), was disrupted by a variety of synthetic chemicals, with the most effective chemical being farnesol. Testing of substrates for presentation of the disruptant chemicals gave some success with rubber or Tygon tubing, although best results were obtained through incorporation of the material into Stikem, which was then banded around tree trunks. Amounts of farnesol used for effective, long residual ant control were between 0.8 and 2 g per tree.     

Tap Reactor for Temporally and Spatially Resolved Analysis of the CO2 Methanation Reaction

Chemical energy carriers produced according to power-to-X concepts will play a crucial role in the future energy system. Here, CO₂ methanation is described as one promising route. However, transient operating conditions and the resulting effects on catalyst stability are to be considered. In this contribution, a tap reactor for spatially and temporally resolved analysis of the methanation reaction is presented. The Ni catalyst investigated was implemented as coating. Reaction data as a function of time and reactor coordinate under various operating conditions are presented and discussed. A comparison with simulation data validates the presented tap reactor concept.     

Supercritical Fluids in Catalysis: Opportunities of In Situ Spectroscopic Studies and Monitoring Phase Behavior

A number of homogeneous and heterogeneous catalytic reactions have been successfully performed in supercritical fluids (SCFs). An overview on recent developments in the areas of alkylation, isomerization, hydrogenation, partial oxidation, amination, and CO₂-fixation using heterogeneous catalysts and supercritical fluids is given. Additionally, strategies towards a more fundamental understanding of catalytic reactions in supercritical fluids are outlined. One aspect is the identification of phase behavior in such multicomponent systems. Their complexity and the input of in situ monitoring is discussed. It is proposed that binary fluid mixtures are an ideal guide for simplifying and understanding the phase behavior in reaction mixtures. In order to strengthen the future use of this knowledge, e.g., for optimization of reactions in SCFs, an overview on the different topologies of binary mixtures is given. Another aspect is in situ characterization of the catalytic reaction and their intermediates, the intermolecular interactions in the fluid, the heterogeneous catalyst phase, and the solid/fluid interphase. The opportunities of various available spectroscopic tools, applicable in situ, are also reviewed by referring to examples from homogeneous catalysis or low-pressure studies.     

Courtship Pheromones in Parasitic Wasps: Comparison of Bioactive and Inactive Hydrocarbon Profiles by Multivariate Statistical Methods

Cuticular hydrocarbons play a significant role in the regulation of cuticular permeability and also in the chemical communication of insects. In the parasitoid Lariophagus distinguendus (Hymenoptera: Pteromalidae), male courtship behavior is mediated by a female-produced sex pheromone. Previous studies have shown that the chemicals involved are already present in the pupal stage of both males and females. However, pheromonal activity in males decreases shortly after emergence. This pheromonal deactivation occurs only in living males, suggesting an active process rather than simple evaporation of bioactive compounds. Here, we present evidence that the sex pheromone of L. distinguendus is composed of a series of cuticular hydrocarbons. Filter paper disks treated with nonpolar fractions of cuticular extracts of freshly emerged males and females, 72-hr-old females, and yellowish pupae caused arrestment and stimulated key elements of courtship behavior in males, whereas fractions of 72-hr-old males did not. Sixty-four hydrocarbons with chain length between C₂₅ and C₃₇ were identified in the fractions by gas chromatography-mass spectrometry (GC-MS). Methyl-branched alkanes with one to four methyl groups were major components, along with traces of n-alkanes and monoalkenes. Principal component analysis, based on the relative amounts of the compounds, revealed that cuticular hydrocarbon composition differed among all five groups. By using partial least squares-discriminant analysis, we determined a series of components that differentiate bioactive and bioinactive hydrocarbon profiles, and may be responsible for pheromonal activity of hydrocarbon fractions in L. distinguendus.