Active low-frequency vibrational-isolation system with compensation of dynamic forces

The feasibility of an active low-frequency vibrational-isolation system with compensation of the dynamic forces on the housing by means of antiphase inertial forces is considered. This system effectively reduces the forces transmitted to the housing from vibrations of an elastically suspended mass in the low-frequency subresonance range.     

Visual attention on the sphere

Human visual system makes an extensive use of visual attention in order to select the most relevant information and speed-up the vision process. Inspired by visual attention, several computer models have been developed and many computer vision applications rely today on such models. However, the actual algorithms are not suitable to omnidirectional images, which contain a significant amount of geometrical distortion. In this paper, we present a novel computational approach that performs in spherical geometry and thus is suitable for omnidirectional images. Following one of the actual models of visual attention, the spherical saliency map is obtained by fusing together intensity, chromatic, and orientation spherical cue conspicuity maps that are themselves obtained through multiscale analysis on the sphere. Finally, the consecutive maxima in the spherical saliency map represent the spots of attention on the sphere. In the experimental part, the proposed method is then compared to the standard one using a synthetic image. Also, we provide examples of spots detection in real omnidirectional scenes which show its advantages. Finally, an experiment illustrates the homogeneity of the detected visual attention in omnidirectional images.     

Grape seed flour is a viable ingredient to improve the nutritional profile and reduce lipid oxidation of frankfurters

In this study, grape seed flour (GSF) obtained from wine by-products was incorporated into frankfurters at seven concentrations (0, 0.5, 1, 2, 3, 4, and 5%) and the effects occurred on physical, nutritional and sensory characteristics of the products were investigated. The colour values (L*, a* and b*) of frankfurters generally decreased (p < 0.05) on account of the increasing amount of GSF. The utilization of this flour also led to a decline in the oxidation level of the products (p < 0.05), probably due to its antioxidant content. The increment of GSF in the frankfurters enhanced the protein, total dietary fibre and water holding capacity of the treatments (p < 0.05). Although the level of GSF above 0.5% reduced overall acceptability, the frankfurters containing the level up to 2% received scores above the average. The evaluation of wine by-products in the production of healthier and functional frankfurters has been achieved by the study, but further research is necessary to improve palatability of the products.     

Fluorescence temperature measurements: Methodology for applications to process monitoring

In previous publications, we described a technique based on fluorescence spectroscopy to monitor resin temperature during processing. The method consists of using optical fiber sensors to monitor fluorescence from a fluorescent dye that has been doped into the processed resin. Temperature is derived from temperature‐induced changes in the fluorescence spectrum. In practice, a temperature calibration function is obtained from the temperature dependence of the ratio of fluorescence intensities at two wavelengths. In this paper, we address several experimental design issues: (a) the supportive role of fluorescence anisotropy measurements to the measuring concept, (b) the experimental setup used for noncontact measurements during capillary rheometry testing, and (c) molecular‐level environmental issues that arise during reactive processing and temperature profiling. We find that fluorescence anisotropy of the dye bis(2,5‐tert‐butylphenyl)‐3,4,9,10‐perylenedicarboximide (BTBP) is independent of shear rate up to 250 s^?1, implying that isotropic orientation of the dye is maintained as the matrix resin undergoes dynamic shear flow, i.e. the calibration function made under quiescent conditions applies to dynamic shear flow conditions. Using this technique in a noncontact application to monitor temperature of the extrudate from a capillary rheometer required an optical design that neutralized the focusing attributes of the cylindrical extrudate. Application to reactive processing is complicated by changes in polarization that accompany the reaction, and, in some cases, produce wavelength shifts in the fluorescence spectrum. We overcome these effects by using a dye that yields a calibration independent of the polarization effects and by averaging over a large dataset to reduce measurement uncertainty. Polym. Eng. Sci. 44:898–908, 2004. © 2004 Society of Plastics Engineers.     

Degradation of 5-hydroxymethylfurfural during yeast fermentation

5-Hydroxymethyl furfural (HMF) may occur in malt in high quantities depending on roasting conditions. However, the HMF content of different types of beers is relatively low, indicating its potential for degradation during fermentation. This study investigates the degradation kinetics of HMF in wort during fermentation by Saccharomyces cerevisiae. The results indicated that HMF decreased exponentially as fermentation progressed. The first-order degradation rate of HMF was 0.693 × 10(-2) and 1.397 × 10(-2)min(-1) for wort and sweet wort, respectively, indicating that sugar enhances the activity of yeasts. In wort, HMF was converted into hydroxymethyl furfuryl alcohol by yeasts with a high yield (79-84% conversion). Glucose and fructose were utilised more rapidly by the yeasts in dark roasted malt than in pale malt (p<0.05). The conversion of HMF into hydroxymethyl furfuryl alcohol seems to be a primary activity of yeast cells, and presence of sugars in the fermentation medium increases this activity.     

Influence of the phenophase on the phenolic profile and antioxidant properties of Dalmatian sage

This study aimed to research the influence of phenophase on the phenolic profile (phenolic acids, flavonoids and stilbenes) and related antioxidant properties of sage, one of the most characteristic plants of Dalmatian karst. The total phenol and flavonoid contents in sage leaves were determined spectrophotometrically, while the principal phenolics were determined using HPLC-RP-DAD. Antioxidant properties of this well known medicinal plant were determined as free radical scavenging activity (DPPH), ferric reducing/antioxidant power (FRAP) and by Briggs-Rauscher oscillating reaction (BR). The results strongly indicate that Dalmatian sage leaves are rich source of valuable phenolics, mainly phenolic acids, with extremely good antioxidant properties. The presence of resveratrol or its derivatives was confirmed in all extracts. The best results for total phenols and flavonoids, as well as the best antioxidant properties were obtained for May sage, while the highest amounts of catechin monomers and compounds from group of stilbenes were found in February extract.     

Ichthyoplankton Assemblages of Coastal West-Central Lake Erie and Associated Habitat Characteristics

Early life stage survival often determines fish cohort strength and that survival is affected by habitat conditions. The structure and dynamics of ichthyoplankton assemblages can tell us much about biodiversity and fish population dynamics, but are poorly understood in nearshore areas of the Great Lakes, where most spawning and nursery habitats exist. Ichthyoplankton samples were collected with a neuston net in waters 2–13 m deep weekly or biweekly from mid-April through August, during 3 years (2000–2002) as part of a study of fish assemblages in west-central Lake Erie. A suite of abiotic variables was simultaneously measured to characterize habitat. Cluster and ordination analyses revealed several distinct ichthyoplankton assemblages that changed seasonally. A lake whitefish (Coregonus clupeaformis) dominated assemblage appeared first in April. In May, assemblages were dominated by several percid species. Summer assemblages were overwhelmingly dominated by emerald shiner (Notropis atherinoides), with large gizzard shad (Dorosoma cepedianum) and alewife (Alosa pseudoharengus) components. This seasonal trend in species assemblages was also associated with increasing temperature and water clarity. Water depth and drift processes may also play a role in structuring these assemblages. The most common and widely distributed assemblages were not associated with substratum type, which we characterized as either hard or soft. The timing of hatch and larval growth separated the major groups in time and may have adaptive significance for the members of each major assemblage. The quality and locations (with reference to lake circulation) of spawning and nursery grounds may determine larval success and affect year class strength.     

Modeling of optical constants of diamond-like carbon

A new model of optical constants of diamond-like carbon parameterizing joint density of states (PJDOS) is introduced and compared with a previously published model based on the parameterization of density of states (PDOS). Both the models employ only six parameters: three parameters for π → π^⁎ and three parameters for the σ → σ^⁎ transitions. These parameters have a clear physical meaning. One describes the minimum energy needed for the band transition, i.e. band gap, the second is the maximum energy of transitions and the third is proportional to the total density of the corresponding electronic states. An inherent disadvantage of the PDOS model is in the necessity of a numerical calculation. On the other hand the PJDOS model is analytical and, therefore, it can be implemented in a simple manner. The efficiency of both the models for the study of DLC structure is demonstrated in several examples.     

Band structure of diamond-like carbon films assessed from optical measurements in wide spectral range

The optical measurements of thin films on substrates, such as ellipsometry and spectrophotometry, can be efficiently used for obtaining information about film material structure if their dielectric function is parametrized by a proper dispersion model. The sample of hydrogenated diamond-like carbon (DLC) film, prepared by plasma enhanced chemical vapor deposition on silicon single crystal substrate, was investigated by ellipsometry in the NIR–UV range (0.6–6.5 eV), synchrotron ellipsometry in the UV–XUV range (4–20 eV) and reflectometry in NIR–UV range (1.24–6.5 eV). Various dispersion models based on the parametrization of density of states (PDOS) were investigated concerning their application in the wide spectral range. The previously used simple PDOS model was found to be insufficient. It resulted in poor separation of π and σ bands in the short spectral range while in the wide range it could not reflect the film optical properties because transitions to higher excited states were neglected. The inclusion of these transitions led to a considerable improvement of the fit above 16 eV. However, the realistic value of the band gap of σ electrons was obtained only after refinement of the previously expected parabolic shape of the DOS of π and σ electrons. The further developed PDOS model can be used for any other disordered material and it will, together with the optical measurements extended to XUV, supply important information about its band structure.