STW resonator with organo-functionalized metallic nanoparticle film for vapor sensing

A 1 GHz surface transverse wave resonator on 36° Y-cut quartz plate coated with organothiol-functionalized gold nanoparticle film has been studied as a chemical gas sensor. Considerable sensitivity of the resonant frequency to vapors of ethanol, methanol, chloroform, and acetic acid has been found. Owing to the high short-term stability of the oscillator built, the detection limit is in the low ppm range. The results qualitatively confirm previous results on the same film type obtained by conductivity measurements. In the present case, the conductivity effect resulting from variable separation of nanoparticles is accompanied with surface-attached mass of the absorbed gas. The film matrix exhibits considerable capacity to absorb large amounts of molecules at high gas concentrations.     

Dynamics of shallow shells with geometrical nonlinearity interacting with fluid

The vibrations of the shallow shell with geometrical nonlinearity submerged in a fluid are considered. Interaction of the shell with a fluid is described by linear hypersingular integral equation, which is solved by the boundary element method. The vibrations of the shell are described by the nonlinear finite-degree-of-freedom system. The vibrations are studied by the Shaw–Pierre nonlinear modes.     

Bifurcations of parametric oscillations of beams with three equilibria

Summary. Nonlinear curvature and nonlinear inertia are taken into account in the beam model. The constant part of the parametric force is proposed to be greater than the buckling one, therefore the beam has three equilibria. One-mode approximation of the beam oscillations is used. Bifurcations of the beam oscillations are analyzed by Melnikov's method. Moreover, beam oscillations close to the stable equilibriums are studied by the multiple scales method.     

The effect of multiple yeasts co-inoculations on Sauvignon Blanc wine aroma composition,sensory properties and consumer preference

Consumer acceptance testing has been only recently applied in wine research, to assess wine sensory attributes that affect hedonic liking. The aim of this study was to investigate the effect of Saccharomyces yeast co-inoculations on wine volatile composition and sensory profiles, and to determine if differences were sufficient enough to affect consumer acceptance. Fermentations were conducted using two- and three-yeast co-inoculations, and single strains. Yeast inocula differed substantially in volatile thiols and other flavour compounds, and in their sensory properties. Wines from four yeast inocula which showed large sensory differences were subjected to consumer testing by 120 consumers, with differences in overall liking found. Four clusters of consumers were identified, with one group strongly preferring the two-yeast co-inoculated wine with an intermediate sensory profile, while another group favoured the wine made using the three-yeast co-inoculation. This study has demonstrated that the yeast inoculum used to conduct fermentation affects consumer acceptance.     

The Saccharomyces cerevisiae alcohol acetyl transferase Atf1p is localized in lipid particles

The yeast alcohol acetyl transferase I, Atf1p, is responsible for the major part of volatile acetate ester production in fermenting Saccharomyces cerevisiae cells. Some of these esters, such as ethyl acetate and isoamyl acetate, are important for the fruity flavours of wine, beer and other fermented beverages. In order to reveal the subcellular localization of Atf1p and further unravel the possible physiological role of this protein, ATF1::GFP fusion constructs were overexpressed in brewer's yeast. The transformant strain showed a significant increase in acetate ester formation, similar to that of an ATF1 overexpression strain, indicating that the Atf1p-GFP fusion protein was active. UV fluorescence microscopy revealed that the fusion protein was localized in small, sphere-like organelles. These organelles could be selectively stained by the fluorescent dye Nile red, indicating that they contained high amounts of neutral lipids and/or sterols, a specific characteristic of yeast lipid particles. Purification of lipid particles from wild type and ATF1 deletion cells confirmed that the Atf1p-GFP fusion protein was located in these organelles. Furthermore, a clear alcohol acetyl transferase activity could be measured in the purified lipid particles of both wild type and transformed cells. The localization of Atf1p in lipid particles may indicate that Atf1p has a specific role in the lipid and/or sterol metabolism that takes place in these particles.     

Comparative Evaluation of Several Pitch Process Models in the Detection of Vocal Tremor

Three models describing the speech excitation wave (denoted as pitch process) are suggested in order to detect vocal tremor in pathological speech. These models are compared, and the advantages and disadvantages of each of them are discussed. Comparison results for synthesized speech are presented, as well as spectral analysis results for real data of Parkinsonian speech, from which it turns out that the pitch process may serve as a powerful tool for detecting such tremor.     

Quasiperiodic forced vibrations of a beam interacting with a nonlinear spring

Summary A simply supported beam with fixed ends and an attached strongly nonlinear spring is considered. As the forced bending vibrations of the beam have moderate amplitudes, the stretching force is a nonlinear function of the deflection. The vibrations are presented as a series with respect to the modes of the beam without attachment. Applying the Bubnov-Galerkin procedure, an infinite system of ordinary differential equations is derived. Using the multiple scales method, the quasiperiodic vibrations in the region of the combination resonance are analyzed in the paper. The system vibrations, when the nonlinear spring is attached in different points, are analyzed. Applicability of the nonlinear spring for mitigation of a combination resonance is discussed.     

Thermal stability and electrical conductivity of Ge20As14(Se x S1-x )52I14 glasses

Investigations of five-component glasses of the Ge₂₀As₁₄(Se _x S_1-x )₅₂I₁₄ type are reviewed for the temperature interval from room temperature to 1273 K. Thermogravimetric analyses enable the determination of the mechanism of thermal decomposition, as well as the range of amorphous phase existence. Electroconductivity was followed by the method of four points under a direct current regime. Semiconductive character was evaluated, as well as the energies of the corresponding energy gaps. The effect of sulphur (i.e. selen) concentrations on the electrical characteristics was also discussed, along with some of the elements significant for determining the mechanisms of electrical conductivity. Results on optical energy gaps were also redetermined.