Aromatic Higher Alcohols in Wine: Implication on Aroma and Palate Attributes during Chardonnay Aging

The higher alcohols 2-phenylethanol, tryptophol, and tyrosol are a group of yeast-derived compounds that have been shown to affect the aroma and flavour of fermented beverages. Five variants of the industrial wine strain AWRI796, previously isolated due to their elevated production of the ‘rose-like aroma’ compound 2-phenylethanol, were characterised during pilot-scale fermentation of a Chardonnay juice. We show that these variants not only increase the concentration of 2-phenylethanol but also modulate the formation of the higher alcohols tryptophol, tyrosol, and methionol, as well as other volatile sulfur compounds derived from methionine, highlighting the connections between yeast nitrogen and sulfur metabolism during fermentation. We also investigate the development of these compounds during wine storage, focusing on the sulfonation of tryptophol. Finally, the sensory properties of wines produced using these strains were quantified at two time points, unravelling differences produced by biologically modulating higher alcohols and the dynamic changes in wine flavour over aging.     

Shaking table experimental study on the effectiveness of polymer bearings for seismic isolation of structures

Seismic isolation has been recognised to be a very effective way of protecting structures from damage during earthquakes. It allows us to extend the natural period of the structure and therefore avoid resonance with the ground motion. Moreover, by increasing damping in the isolation devices, more energy can be dissipated and thus the structural response can be further reduced. The aim of this paper is to show the results of the study focused on verification of the applicability of the innovative method of seismic isolation by installing bearings made of a polymer mass, which is an especially designed flexible elastoplastic two-component grout based on polyurethane resin. In the study, a model structure was tested experimentally on a shaking table under earthquake excitation. First, the structure was fixed directly to the table and its response was recorded. Then, the response of the structure with polymer bearings installed at its base was observed and both responses were compared. The results of the study show that equipping the structure with the polymer bearings can considerably reduce the structural response under earthquake excitation. The innovative method considered in the study has been verified to be an effective seismic isolation technique. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Theoretical studies of l-ascorbic acid (vitamin C) and selected oxidised, anionic and free-radical forms

Calculations were carried out at the restricted and unrestricted B3LYP/6-311++G(d,p) and B3LYP/EPR-II levels for two conformers (1 and 2) of l-ascorbic acid and their respective oxidation products to di- and monodehydroascorbates. For the didehydroascorbates, corresponding to Conformer 1, free radical properties are compared with previously published calculations in the gaseous and aqueous solution states and with experimental EPR values. Calculated molecular structures, EPR and vibrational spectral and energetic properties are reported including some proposed changes to previous EPR assignments. Conformer 2 of l-ascorbic acid is predicted to have lower energy than Conformer 1, under the method and basis sets used, by between 11 and 26 kJ mol⁻¹ and is stabilised by internal hydrogen bonding. For particular monodehydroascorbates, formed by loss of H from the chain CH(OH) group, calculated properties of conformers of five neutral mono-radicals and the corresponding five anionic di-radicals are reported. Relaxed potential energy surface (PES) scans were carried out for two proton transfer processes and relative energies of stable minima and barriers between them determined. The physiological significance of the protective oxidation of l-ascorbic acid by free radicals is briefly described.     

Reverse task as a designing of mechatronic vibrating branched systems

In this paper a new approach for designing mechatronic vibrating branched structures has been presented. Mechatronic structures have been built from mechanical discrete systems connected to piezoelectric actuator and externalL_xR_xC_x network, with different configurations. Modeling simplification has been performed by use of non dimensional transformations and retransformations. In each case reverse task has been solved by distribution into partial fraction method in respect to required dynamic properties in form of frequency spectrum: resonant and anti resonant frequencies. Furthermore, different configurations of final L_xR_xC_x network have been presented. These considerations have been supported by calculation examples, and all results have been presented in the graphical form. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

An experimental and theoretical investigation of gas-phase reactions of Ca2+ with glycine

The gas-phase reactions between Ca(2+) and glycine ([Ca(gly)](2+)) have been investigated through the use of mass spectrometry techniques and B3-LYP/cc-pWCVTZ density functional theory computations. The major peaks observed in the electrospray MS/MS spectrum of [Ca(gly)](2+) correspond to the formation of the [Ca,C,O(2),H](+), NH(2)CH(2) (+), CaOH(+), and NH(2)CH(2)CO(+) fragment ions, which are produced in Coulomb explosion processes. The computed potential energy surface (PES) shows that not only are these species the most stable product ions from a thermodynamic point of view, but they may be produced with barriers lower than for competing processes. Carbon monoxide is a secondary product, derived from the unimolecular decomposition of some of the primary ions formed in the Coulomb explosions. In contrast to what is found for the reactions of Ca(2+) with urea ([Ca(urea)](2+)), minimal unimolecular losses of neutral fragments are observed for the gas-phase fragmentation processes of [Ca(gly)](2+), which is readily explained in terms of the topological differences between their respective PESs.     

Determination of protein oxidation by mass spectrometry and method transfer to quality control

Characterization and quantitative analysis of oxidation plays an important role in biopharmaceutical development. This study demonstrates an approach to the assessment of susceptible to oxidation methionine residues in monoclonal antibodies and recombinant proteins. A method for the determination of oxidation levels by peptide mapping with mass spectrometric (MS) detection is described and its advantages compared to the UV detection are presented. Good linearity and reproducibility for determination of oxidation with MS detection are demonstrated (R2 > 0.99; RSDs of 4-9%). Aspects of method transfer to quality control group (QC) are discussed. As well, a quick and easy flow injection/MS method is proposed to substitute for peptide map analysis. Peptide coverage, linearity, reproducibility, robustness, sensitivity and quantitative oxidation results are compared for the flow injection/MS and LC/MS approaches.     

Rapid and accurate measurement of transverse relaxation times using a single shot multi-echo echo-planar imaging sequence

Methods for making rapid and accurate measurements and maps of the transverse relaxation time from a single free induction decay (FID) are proposed. The methods use a multi-echo sequence in combination with B1 insensitive (hyperbolic secant or BIREF2b) refocusing pulses and rapid echo-planar imaging techniques. The results were calibrated against a single spin echo echo-planar imaging sequence using a phantom containing a range of CuSO4 concentrations. The mean percentage absolute difference between the multi-echo and single-echo results was 3% for the multi-echo sequence using the hyperbolic secant refocusing pulse, and 7% for the multi-echo sequence using the BIREF2b refocusing pulse, compared to 13% for a multi-echo sequence using a nonselective sinc refocusing pulse. The use of the sequences in vivo has been demonstrated in studies of gastric function, i.e., the measurement of gastric dilution and monitoring of formation of a raft of alginate polysaccharide within the stomach.     

Polyethyleneimine coating renders polycarbonate resistant to organic solvents

We propose a method for the modification of surfaces of microchannels in chips fabricated in polycarbonate (PC) that makes the devices resistant to a range of organic solvents. Coating of PC with branched polyethyleneimine (BPEI) with the use of trimethylpropane triglycidyl ether (TTE) as a linker renders the devices resistant to toluene, benzene, acetonitrile, tetrahydrofuran, dioxane and ethylene dichloride. The optimized procedure of modification allows for continuous operation of the chips for several hours without dissolution of PC. Additional modification with the use of Krytox? allows for the use of Fluorinert (FC-40) as the continuous phase and for generation and handling of droplets of organic solvents that are miscible with water.