High variation of congener alcohols in apple wines.

Congener alcohol (CA) analysis became an important tool in forensic science to prove the kind of alcoholic beverage consumed. The aim of the present study was to determine the influence of yeast strain and apple variety on the formation of congener alcohols in self-produced apple wine. There exist data on CA patterns of industrially produced alcoholic beverages, but these are not available for apple wine. Must from five different commercial as well as from six genuine apple varieties were used for fermentation under similar conditions CA formation was monitored during the fermentation process. Additionally, nine commercial apple wines from commercial producers were analyzed. Analysis was performed by headspaces-GC-MS. All apple wines contained markedly high contents of the CA 3-methylbutan-1-ol (88-251 mg/L). Compared to self-produced apple wines from genuine musts the industrial apple wines (purchased in supermarkets and self-produced from commercial musts) exhibited significant differences in methanol concentrations(8.5-94 mg/L), whereas all other CAs, such as propan-1-ol, butan-1-0l, 2-methylpropan-1-ol(isobutanol), 3-methyl-butan-1-oi, and 2-methylbutan-1-oi, were found to be present in similar concentrations. Methanol was not detectable in apple wine made from genuine musts during fermentation but after a storage period. In some cases, concentrations of some CAs additionally changed during storage. This may be explained by a secondary (unwanted) fermentation after bottling. According to the data obtained in the present study, it is recommended to analyze a sample of the allegedly consumed apple wine in forensic cases, rather than to rely on data obtained from the literature or from some data collections.

Novel controllable auxetic effect of linearly elongated supported polyelectrolyte multilayers with amorphous structure.

Polyelectrolyte multilayers (PEMs) deposited on flexible supports are promising candidates for many applications ranging from controlled wettability over stimuli responsive nanovalves to lithography free surface structuring. Since many potential applications involve elongation of these films, we investigated the effect of elongation on the PEM thickness and density with ellipsometry. To our surprise PEM films with known amorphous internal structure show auxetic behavior that depends on the PEM preparation condition. The measured refractive index was compared with simulated values using the Garnet equation to evaluate if the incorporation of water or air causes the observed phenomena.

Spatial risk assessment of radiocesium contamination of edible mushrooms - Lessons from a highly frequented recreational area.

The radioactive contamination of edible mushrooms increases human health hazards, especially in high mushroom collection intensity areas. Today only coarse-scale data with low spatial resolution are available, which prevents us from predicting human risk. To reduce the risk for human health, we need spatially explicit recommendations at landscape-scale. We used the Bavarian Forest National Park, a famous mushroom hunting location in Europe, as a model system. We aimed to increase the predictability of the contamination of the two most prominent mushroom species, bay boletus (Imleria badia) and ceps (Boletus edulis), and provide an efficient evidence-based risk assessment at landscape-scale. We revealed a high and a low 137Cs-activity impact area based on soil samples, which is also reflected by the mushroom species. 137Cs-activity of Imleria badia is about five times higher than the contamination of Boletus edulis; with one-third of the Imleria badia samples being over the statutory limit. The difference of contamination between species is more pronounced in the high-impact area. Elevation is a strong predictor in contrast to orientation of slopes. In high-impact areas, mushrooms showed higher 137Cs-activities at lower elevations. Soil analysis revealed that the maximum of the 137Cs-activity is still in the organic layers, indicating further mushroom contamination. We recommend using only Boletus edulis in the low-impact area for diet. We suggest that Boletus edulis bear a lower health risk than Imleria badia due to lower 137Cs-activities. Nevertheless, we need more landscape-scale studies to assess the 137Cs contamination risk for humans. Studies are primarily important in high-impact areas, which can be roughly identified by using soil contamination maps. The focus should be on high accumulating mushroom species like Imleria badia. Our study can serve as a blueprint to rapidly assess human health risks caused by radioactive contamination in landscapes intensively used by mushroom collectors.

Adsorption of GST-PI3Kgamma at the air-buffer interface and at substrate and nonsubstrate phospholipid monolayers.

The recruitment of phosphoinositide 3-kinase gamma (PI3Kgamma) to the cell membrane is a crucial requirement for the initiation of inflammation cascades by second-messenger production. In addition to identifying other regulation pathways, it has been found that PI3Kgamma is able to bind phospholipids directly. In this study, the adsorption behavior of glutathione S-transferase (GST)-PI3Kgamma to nonsubstrate model phospholipids, as well as to commercially available substrate inositol phospholipids (phosphoinositides), was investigated by use of infrared reflection-absorption spectroscopy (IRRAS). The nonsubstrate phospholipid monolayers also yielded important information about structural requirements for protein adsorption. The enzyme did not interact with condensed zwitterionic or anionic monolayers; however, it could penetrate into uncompressed fluid monolayers. Compression to values above its equilibrium pressure led to a squeezing out and desorption of the protein. Protein affinity for the monolayer surface increased considerably when the lipid had an anionic headgroup and contained an arachidonoyl fatty acyl chain in sn-2 position. Similar results on a much higher level were observed with substrate phosphoinositides. No structural response of GST-PI3Kgamma to lipid interaction was detected by IRRAS. On the other hand, protein adsorption caused a condensing effect in phosphoinositide monolayers. In addition, the protein reduced the charge density at the interface probably by shifting the pK values of the phosphate groups attached to the inositol headgroups. Because of their strongly polar headgroups, an interaction of the inositides with the water molecules of the subphase can be expected. This interaction is disturbed by protein adsorption, causing the ionization state of the phosphates to change.

In situ FTIR ATR spectroscopic study of the interaction of immobilized human tumor necrosis factor-alpha with a monoclonal antibody in aqueous environment.

By in situ FTIR ATR measurements, the antibody (AB) recognition of human tumor necrosis factor-alpha (TNFalpha) immobilized on the Ge surface of a multiple internal reflection element (MIRE) was investigated. The experiments were performed in aqueous environment in a flow-through cell. After immobilization of TNFalpha on the Ge-MIRE by direct adsorption from aqueous solution, the immobilisate reached stability after about 1 h under flow-through conditions. The remaining sites of the Ge surface were saturated by bovine serum albumin (BSA) in order to prevent unspecific binding of anti-TNFalpha AB which was then added. The obtained FTIR ATR spectra were shown to result exclusively from AB specifically interacting with TNFalpha, since the absence of immunoglobulin binding to BSA adsorbed to the Ge MIRE was verified by a reference experiment. Finally, the stability of all adsorbed protein immobilisates was monitored under flow-through conditions for 10.5 h. The TNFalpha-AB complex showed a decrease of 7.4%, whereas the BSA adsorbate remained stable. IR measurements were performed with polarized light in order to study orientational effects of the immobilized proteins. The dichroic ratios and surface concentrations of all used proteins are available after quantitative analysis of the amide II bands.

Evidence for heterodimers of 2,4,5-trichlorophenol on planar lipid layers. A FTIR-ATR investigation.

Trichlorophenols are weak acids of high hydrophobicity and are able to transport protons across the mitochondrial membrane. Thus the proton motive force is dissipated and the ATP production decreased. In situ Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR) experiments with 2,4,5-trichlorophenol (TCP) adsorbed to model membranes resulted in good evidence for the formation of the TCP-heterodimer. Two surfaces were examined: a dipalmitoyl phosphatidic acid (DPPA) monolayer and a planar DPPA/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer. TCP was adsorbed from 1 to 3 mM solutions at pH 6.0 to the lipid layers leading to surface layers at the water/lipid interface. Difference spectra showed an effect on DPPA acyl chains even when it was covered with POPC. Time-resolved measurements revealed two distinct adsorption processes, which were assigned to TCP and its deprotonated anion (phenoxide), respectively. For DPPA/POPC bilayers, the adsorption of TCP was faster than that of its phenoxide, whereas adsorption of both species to DPPA monolayers proceeded with similar velocity. In both cases, phenoxide formation at the membrane was found to be delayed with respect to phenol adsorption. Phenoxide and phenol were retained after replacing the TCP solution with buffer. For the retained species, we estimated a phenol/phenoxide molar ratio of 1 at pH 6.0 (pKa=6.94 for TCP), demonstrating strong evidence for heterodimer formation.

Effect of linear elongation of PDMS-supported polyelectrolyte multilayer determined by attenuated total reflectance IR radiation.

Polyelectrolyte multilayers (PEMs) deposited on flexible supports, such as silicone rubber, show interesting properties upon elongation and release, like controlled wrinkling, elongation-based wetting, or dewetting and stimuli responsive nanovalves. To understand the underlying physical effects of PEM experiencing linear elongation, the orientation change of molecular groups within PEM experiencing linear elongation was investigated. The model PEM consists of polystyrenesulphonate and polydimethyldiallyl chloride. The investigation method was infrared attenuated total reflectance. In the study, the orientation change of the benzene and the sulfate groups of polystyrenesulphonate upon elongation of the PEM, prepared at high and low ionic strengths, was tracked. The gained results show that the benzene group shows no sign of orientation change upon elongation, whereas the sulfate group does, whereby the reorientation depends on the ionic strength of the preparation solution. Upon release of elongation, the PEM prepared at low ionic strength shows no orientation change, whereas PEM prepared at high ionic strength does show further orientation change, indicating that the formed wrinkles elongate the PEM on the top of the wrinkles.

In situ ATR FTIR monitoring of the formation of functionalized mono- and multilayers on germanium substrate: from 7-octenyltrichlorosilane to 7-carboxylsilane.

The development and optimization of biomimetic surfaces required for biosensors and medical assays are made more efficient by quantitatively monitoring the surface chemical reactions in situ by means of attenuated total reflection (ATR) FTIR spectroscopy. single-beam-sample-reference (SBSR) ATR, as well as modulated excitation (ME), techniques have been applied to get physicochemical information on growth and structure of the surface layer. SBSR and ME methods result in optimum background compensation and signal-to-noise ratio. Surface modification was performed on a germanium multiple internal reflection element (Ge-MIRE). Activation of the surface resulted in free Ge-OH groups used for a spontaneous chemical reaction with 7-octenyltrichlorosilane (7-OTCS) in toluene. Formation of Ge-O-Si bonds was enabled by hydrolization of Si-Cl3 after partial elimination of a tightly bound thin water layer covering the MIRE. Unwanted side-reaction by hydrolization of Si-Cl3 in solution followed by polymerization paralleled this process. Steady growing of the silane layer to multilayer thickness with increasing time was observed in all experiments. Most unexpectedly, in some experiments the end-standing double bond of the silane layer was found to be partly oxidized even after being exposed only to toluene, probably because of catalysis by molecular sieve nanoparticles remaining in toluene after drying. Finally, theoretical means are presented enabling the calculation of the spectrum of dissolved 7-OTCS in toluene, a prerequisite for background compensation during in situ studies of the growing layer.