Extracts obtained by supercritical carbon dioxide extraction of cones and leaves of hop (Humulus lupulus L) at different combinations of temperature and pressure were analysed for their α- and β-acids and volatiles, using HPLC and GC respectively. The yield and composition of the mixtures of bitter compounds from the cones were largely influenced by the temperature and pressure applied during the extraction. Bitter compounds could not be detected in the extracts from the leaves. The most important volatile components identified were β-myrcene, β-caryophyllene and α-humulene. The extraction parameters also influenced the composition of the mixture of volatiles from the cones and leaves, 40°C and 20.0 MPa being optimum for the extraction of both bitter compounds and volatiles, which are thought to be important for the aroma of beer. 相似文献
This paper presents a study on the influence of nonideal sampling in asynchronous Q-factor monitoring. An overestimation of the Q-factor of signals impaired with optical noise may occur if the averaging effects due to nonideal sampling affect only the noise component of the monitored signal. It is shown that this problem can be rectified using a correction factor, dependent only on the receiver parameters. This allows reasonable Q-factor estimates using sampling systems with aperture times close to the monitored signal bit period. Nonideal sampling may also affect the signal component of the monitored signal. For such cases, a novel and accurate technique is presented to estimate the Q factor using asynchronous histograms, which takes into account changes in the shape of the monitored signal due to averaging effects. Numerical simulations are used to evaluate the proposed technique achieving Q-factor estimates within a 14% error margin, independently of the sampling aperture for the considered range. Distortion affecting the signal due to the transmission system can also be handled by the new technique presented in this paper. It is verified that the impact of intersymbol interference due to chromatic dispersion or electrical filtering in the receiver on the performance of the system is well reflected by the estimated Q factor. 相似文献
3D x-ray tomography is a powerful scanning technique used for generating images of complex fibre structures. A novel machine-learning algorithm to identify and separate individual fibres using 3D images is proposed in this article. The developed four-step hybrid 3D fibre segmentation algorithm involves deep-learning aided semantic segmentation that slices 3D images to create 2D images for fibre extraction, elliptical contour estimation combined with the marker-controlled watershed algorithm for separating fibres from the background area, identifying individual fibres through 3D reconstruction, and, lastly, the 3D object refining approach based on outlier object detection and replacement. The proposed methodology is implemented on a real-time sample of nylon fibre bundle under compression and its 3D x-ray image volume to validate the performance. The results show its superior performance compared to off-the-shelf image processing algorithms in terms of precision, that is, with a validation accuracy greater than 90%, and efficiency, that is, preventing the need for a huge data set and reducing the complexity. 相似文献
This paper presents a study of friction stir welding of aluminium and copper using experimental work and theoretical modelling. The 5083-H116 aluminium alloy and pure copper were successfully friction-stir-welded by offsetting the pin to the aluminium side and controlling the FSW parameters. A theoretical analysis is presented along with key findings. The process temperatures are predicted analytically using the inverse heat transfer method and correlated with experimental measurements. The temperature distribution in the immediate surroundings of the weld zone is investigated together with the microstructures and mechanical properties of the joint. This was supported by a finite element analysis using COMSOL Multiphysics. In this study, two rotational speeds were used and a range of offsets was applied to the pin. The microstructure analysis of the joints was undertaken. This revealed some particles of Cu inclusion in the nugget zone. The energy dispersive spectroscopy showed a higher diffusion rate of aluminium towards the interface while copper maintained a straight base line. 相似文献
Encapsulation of hydrophobic plant essential oil components (EOC) into surfactant micelles can assist the decontamination of fresh produce surfaces from bacterial pathogens during postharvest washing. Loading of eugenol and carvacrol into surfactant micelles of polysorbate 20 (Tween 20), Surfynol® 485W, sodium dodecyl sulfate (SDS), and CytoGuard® LA 20 (CG20) was determined by identification of the EOC/surfactant‐specific maximum additive concentration (MAC). Rheological behavior of dilute EOC‐containing micelles was then tested to determine micelle tolerance to shearing. Antimicrobial efficacy of EOC micelles against Escherichia coli O157:H7 and Salmonella enterica serotype Saintpaul was first evaluated by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Pathogen‐inoculated spinach was treated with eugenol‐containing micelles applied via spraying or immersion methods. SDS micelles produced the highest MACs for EOCs, while Tween 20 loaded the lowest amount of EOCs. Micelles demonstrated Newtonian behavior in response to shearing. SDS and CG20‐derived micelles containing EOCs produced the lowest MICs and MBCs for pathogens. E. coli O157:H7 and S. Saintpaul were reduced on spinach surfaces by application of eugenol micelles, though no differences in numbers of surviving pathogens were observed when methods of antimicrobial micelle application (spraying, immersion) was compared (P ≥ 0.05). Data suggest eugenol in SDS and CG20 micelles may be useful for produce surface decontamination from bacterial pathogens during postharvest washing. 相似文献
Mine drainage from the St Louis Tunnel (located at the Rico-Argentine Site) is circumneutral most of the year, with spring freshets increasing flow, decreasing pH and increasing metals concentrations. This study was designed to test the performance of a demonstration-scale horizontal wetlands passive treatment train, comprised of a settling basin, surface flow wetland, horizontal-flow anaerobic wetland, aeration channel, and rock drain, during two years of influent water chemistry at a constant 113 L/min (30 gpm) flow rate. Total Zn, Cd, and Mn effluent concentrations met project treatment goals (PTGs) 75, 96.9, and 100% of the time, respectively, and 93.9, 100, and 100% of the time for the dissolved metals. Most PTG exceedances occurred during the freshet events. Most Zn and Cd attenuation was attributed to sulfide precipitation in the anaerobic cell and capture/filtration of suspended ZnS particles in the anaerobic wetland and rock drain. Manganese was attenuated in the aerobic portion of the anaerobic cell (influent transition zone) as Mn oxides and carbonates. Oxidation of Mn occurred in the rock drain as biogenically formed Mn oxides adhered to the rock matrix. Carryover of dissolved sulfides from the anaerobic cell limited the rock drain’s Mn removal efficiency. Low temperatures did not significantly affect biological activity within the system; the effects of seasonal water quality were more important.