To extend shelf life, the effects of polyvinylchloride film (PVC) and edible coatings on quality aspects of refrigerated Brussels sprouts were studied. Starch-based coatings were formulated using glycerol (G), sorbitol (S) or glycerol plus sunflower oil (O). Sprouts so treated as well as uncoated ones were placed on expanded polystyrene trays. Combinations of PVC and coatings (treatments named G-PVC, S-PVC and O-PVC) were also tested. Uncovered trays were maintained as controls. All packages were stored at 0 °C for 42 days and samples were removed every 14 days to determine commercial acceptability, weight loss, surface colour (of sprouts’ heads and bases) and texture. Sprouts in all treatments maintained optimum quality conditions over the first 14 days. At the end of storage, browning of cut zones and losses in weight and firmness were minimised in PVC-packaged sprouts, particularly in G-PVC. Therefore, PVC and G-PVC treatments were selected to evaluate some nutritional quality components. Ascorbic acid and total flavonoid contents remained almost constant while radical scavenging activity increased after 42 days of storage. Thus, PVC and G-PVC treatments showed the best performance for long-term refrigerated storage of Brussels sprouts. 相似文献
Burrowing mayfly species of the genus Hexagenia are well known indicators of environmental health in lakes and rivers. Two species, H. limbata and H. rigida, are indistinguishable as nymphs and as adult females. Our objectives were to develop a genetic technique to distinguish between the two species and identify morphological features that separate cryptic nymphs and adult females. Fifty nymphs were collected before emergence from 10 sites throughout the western basin of Lake Erie in 2004 and 2005. Using known specimens of adult aerial male H. limbata and H. rigida, we used the mitochondrial cytochrome c oxidase subunit 1 (COI) gene to identify a 16 base pair (bp) difference between species. DNA sequencing confirmed correct species identification based on differences in abdominal pigmentation patterns on adult female imagos in 19 of 20 cases; the lone exception was a female with very faint pigmentation. Pigmentation patterns between species were consistent on nymphs, subimagos and imagos of both sexes. Populations of both species are panmictic across the western basin of Lake Erie, but H. limbata is the numerically dominant species, representing 70 to 100% of nymphs at sites in both years. A separate lineage of H limbata was discovered in the samples. The ability to distinguish nymphs of the two species will aid in developing more sensitive ecosystem indicators. 相似文献
Vibration-based damage detection methods have become widely used because of their advantages over traditional methods. This paper presents a new approach to identify the crack depth in steel beam structures based on vibration analysis using the Finite Element Method (FEM) and Artificial Neural Network (ANN) combined with Butterfly Optimization Algorithm (BOA). ANN is quite successful in such identification issues, but it has some limitations, such as reduction of error after system training is complete, which means the output does not provide optimal results. This paper improves ANN training after introducing BOA as a hybrid model (BOA-ANN). Natural frequencies are used as input parameters and crack depth as output. The data are collected from improved FEM using simulation tools (ABAQUS) based on different crack depths and locations as the first stage. Next, data are collected from experimental analysis of cracked beams based on different crack depths and locations to test the reliability of the presented technique. The proposed approach, compared to other methods, can predict crack depth with improved accuracy. 相似文献
Herein we wish to report a new non‐enzymatic kinetic resolution of racemic 4‐formyl[2.2]paracyclophane based on Noyori asymmetric transfer hydrogenations (KR‐ATH). Our approach, which provides an efficient access to enantiopure (Rp)‐ and (Sp)‐4‐formyl[2.2]paracyclophane (>99% ee, 39% and 41% isolated yields, respectively), is operationally simple and can be run on the gram‐scale thus confirming the practical applicability of this method.
Aligned multi-walled carbon nanotube forests were grown by chemical vapour deposition on carbon fibers by the use of an amorphous Si interface. The Si layer creates a barrier, hindering the Fe catalyst diffusion into the carbon fibers. This method provides a way to tailor the thermal, electrical and mechanical properties of the fiber-resin interface of a polymer composite. 相似文献
Lipid ingredients that demonstrate high stability and positive health profiles without the use of trans‐fats are needed in the food supply. Rice bran oil can be fractionated at low temperatures to create a series of spreads that show promise as functional ingredients. A rice bran oil‐derived spread can extend the fry life of soybean oil and can also be incorporated into baked goods such as bread and granola as a trans‐fat free alternative to butter or shortening. 相似文献
Small scale lean combustors, in conjunction with mechanical and electrical conversion devices, have the potential to meet increasing portable power needs. This study examines the combustion of lean premixed fuels in a mesoscale, heat-recirculating parallel-plate counter-flow reactor. The reactor utilizes internal heat recirculation to produce temperatures in excess of the adiabatic flame temperature, known as superadiabatic combustion. As a result of these elevated temperatures, burning velocities above adiabatic values and extension of flammability limits, including stable operation at very lean equivalence ratios, may be attained. Combustor stability and emissions of carbon monoxide, nitrogen oxides, and unburned hydrocarbons have been previously studied for lean combustion of methane in the counter-flow reactor. This study examines lean combustion of two increasingly complex fuels, propane and heptane, due to the logistical importance of both gaseous and liquid fuels. Stability ranges and emissions measurements are presented for the counter-flow reactor operating on these fuels, and the results are compared to previously measured emissions for lean methane. Stability ranges of the counter-flow reactor operating on lean propane and heptane are also compared to those in the rich regime. Further analysis of the results for lean methane, propane and heptane combustion utilizes peak reactor wall temperatures as an indicator of favorable operating conditions, and highlights the importance of superadiabatic operation for achieving large turn-down ratios and low levels of emissions. 相似文献