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排序方式: 共有336条查询结果,搜索用时 31 毫秒
81.
Markus Takkunen Jyrki Ågren Johanna Kuusisto Markku Laakso Matti Uusitupa Ursula Schwab 《Lipids》2013,48(11):1093-1102
Erythrocyte membrane fatty acid (EMFA) composition is used in the validation of food frequency questionnaires (FFQ) and the evaluation of dietary fat quality. In this cross-sectional study we aimed to investigate associations of diet with EMFA. Altogether, 1,033 randomly selected Finnish men, aged from 47 to 75 years filled in a FFQ and their EMFA composition was analyzed. Marine polyunsaturated fatty acid (PUFA) intake correlated positively with erythrocyte eicosapentaenoic and docosahexaenoic acids (r s = 0.415 and r s = 0.340, respectively, P < 0.001) and inversely with all n-6 PUFA analyzed (P < 0.001). PUFA intake from spreads and cooking fats correlated positively with alpha-linolenic (ALA), linoleic (LNA) and nervonic acids (r s = 0.229, r s = 0.160 and r s = 0.143, respectively, P < 0.001). Milk fat intake was associated with myristic and behenic acids (r s = 0.186 and r s = 0.132, respectively P < 0.001). Butter users had lower ALA and LNA proportions (mol%) than non-users (0.16 ± 0.04 vs. 0.19 ± 0.05, P < 0.001 and 7.77 ± 1.02 vs. 8.12 ± 1.11, P = 0.001). Higher PUFA intake from meat was related to decreased long-chain n-3 (P < 0.001) and increased n-6 PUFA (P < 0.001) proportions. In conclusion, EMFA composition reflects particularly well the intakes of n-3 PUFA, whereas other associations remained lower. Yet, all main sources of dietary fat were related with EMFA. The dietary effect on the nervonic acid proportion was confirmed. 相似文献
82.
Study of the PM Gas-Phase Filter Artifact Using a Setup for Mixing Diesel-Like Soot and Hydrocarbons
Richard Högström Panu Karjalainen Jaakko Yli-Ojanperä Antti Rostedt Martti Heinonen Jyrki M. Mäkelä 《Aerosol science and technology》2013,47(9):1045-1052
The filter artifact is a significant source of error in gravimetric measurements of particulate matter (PM) exhaust. However, only a few studies on the subject exist. Results from these studies show a large discrepancy mainly because the experiments were performed using real diesel vehicle exhaust with varying exhaust composition. In this study, a setup for mixing diesel-like soot and hydrocarbon vapor was constructed for generating a stable exhaust aerosol with adjustable composition. The particle size distribution of the diesel-fueled soot generator (GMD [geometric mean diameter] adjustable between 27 and 164 nm) was found to represent “real” exhaust particulate emission. This setup was applied for studying the filter artifact on Teflon-coated glass fiber filters using pentadecane as the hydrocarbon vapor. Experiments were performed using particle and hydrocarbon concentrations of 130–700 μg/m3 and 10–12 ppm, respectively. It was found that the particle concentration of the aerosol affects the filter artifact. At lower particle concentrations, more hydrocarbon adsorption was detected. In the absence of particles, the adsorption was highest. Furthermore, filter soot load, corresponding to 0.13%–0.66% of the clean filter mass, was found to affect adsorption. Sooty filters adsorbed less vapor than clean filters. However, increasing the soot load resulted in more adsorption. Moreover, it was found that the backup filter serves as a reasonable estimate of the filter artifact only for low particle concentrations and filter soot loads. These results indicate that the filter soot load is an important parameter influencing the filter artifact, and therefore, it should be considered when performing gravimetric sampling. The setup was proven to be a unique tool for quantitative studies of the filter artifact. Copyright 2012 American Association for Aerosol Research 相似文献
83.
We describe a new interactive learning-oriented method called Pareto navigator for nonlinear multiobjective optimization.
In the method, first a polyhedral approximation of the Pareto optimal set is formed in the objective function space using
a relatively small set of Pareto optimal solutions representing the Pareto optimal set. Then the decision maker can navigate
around the polyhedral approximation and direct the search for promising regions where the most preferred solution could be
located. In this way, the decision maker can learn about the interdependencies between the conflicting objectives and possibly
adjust one’s preferences. Once an interesting region has been identified, the polyhedral approximation can be made more accurate
in that region or the decision maker can ask for the closest counterpart in the actual Pareto optimal set. If desired, (s)he
can continue with another interactive method from the solution obtained. Pareto navigator can be seen as a nonlinear extension
of the linear Pareto race method. After the representative set of Pareto optimal solutions has been generated, Pareto navigator
is computationally efficient because the computations are performed in the polyhedral approximation and for that reason function
evaluations of the actual objective functions are not needed. Thus, the method is well suited especially for problems with
computationally costly functions. Furthermore, thanks to the visualization technique used, the method is applicable also for
problems with three or more objective functions, and in fact it is best suited for such problems. After introducing the method
in more detail, we illustrate it and the underlying ideas with an example. 相似文献
84.
Kaisa Grönman Risto Soukka Terhen Järvi‐Kääriäinen Juha‐Matti Katajajuuri Mika Kuisma Heta‐Kaisa Koivupuro Margareetta Ollila Marja Pitkänen Olli Miettinen Frans Silvenius Rabbe Thun Helena Wessman Lassi Linnanen 《Packaging Technology and Science》2013,26(4):187-200
The environmental impacts of packages have been found to be relatively small compared with the food items they contain. Furthermore, from the environmental and operational point of view, the most significant task of the package is to protect the product, which is important to acknowledge in the packaging design process. This study introduces a guiding framework for designing sustainable food packaging. In this approach, the entire life cycle of the product–package combination is taken into consideration. The emphasis is on the prevention of food losses in packaging design as a major environmental criterion. Consideration of the properties of both the package and the product itself when designing the final package will lead to a better end result with smaller product losses and environmental impacts. By using different assessment methods in the different stages of the packaging design, the sustainability of the package can be enhanced. The decision making of the packaging designer is facilitated with methods that are introduced step by step and in a certain order that will also allow for corrective measures through back‐loops in the design process. The purpose is to integrate sustainability aspects at all stages firmly into the design process. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
85.
Through an innovative trade-in-task case study, we explore how Nokia, which is historically one of the most important mobile phone manufacturers in the world, offshored the development and production of three distinct mobile phones at three different points in time. Adjacent to these processes, we find that the value creation in areas such as design and manufacturing knowledge has rapidly shifted away from advanced economies to emerging economies. Moreover, we find that the value added captured by Nokia decreased dramatically over the studied time period. Based on our results, we uss more generally the challenge of multinational corporations to preserve value and how the realisation of the benefits of offshoring must be assessed with respect to the altered requirements for controlling value-adding activities. 相似文献
86.
Natural rubber (NR) is a versatile material possessing outstanding mechanical properties, which can be used in multiple applications including the rapidly developing dielectric elastomer generators (DEGs). One of the drawbacks of the existing DEGs is their low efficiency, which can be improved by lowering the dielectric and mechanical losses originating from the material. Therefore, the present research was focusing on assessing the ways to minimize the dielectric and mechanical losses of NR films rather than developing a DEG. In this article, the effect of natural proteins and the rubber stabilizers on energy dissipation of NR films was evaluated. Moreover, the effect of sample posttreatment (with water and acetone), curing and time after cure was discussed. As a result, deproteinized NR stabilized by ammonium caseinate outperformed unmodified NR due to reduced dielectric losses, mechanical hysteresis and stress relaxation. Moreover, the posttreatment methods were found to moderately reduce the material-relates losses. 相似文献
87.
Journal of Intelligent Manufacturing - Optimization of operations and maintenance (O&M) in the industry is a topic that has been largely studied in the literature. Many authors focused on... 相似文献
88.
89.
Helvi M. Vidgren Jyrki J. Ågren Ursula Schwab Tiina Rissanen Osmo Hänninen Matti I. J. Uusitupa 《Lipids》1997,32(7):697-705
The effects of n-3 fatty acid supplementation in the form of fresh fish, fish oil, and docosahexaenoic acid (DHA) oil on the
fatty acid composition of plasma lipid fractions, and platelets and erythrocyte membranes of young healthy male students were
examined. Altogether 59 subjects (aged 19–32 yr, body mass index 16.8–31.3 kg/m2) were randomized into the following diet groups: (i) control group; (ii) fish diet group eating fish meals five times per
week [0.38±0.04 g eicosapentaenoic acid (EPA) and 0.67±0.09 g DHA per day]; (iii) DHA oil group taking algae-derived DHA oil
capsules (1.68 g/d DHA oil group taking algae-derived DHA oil capsules (1.68 g/d DHA in triglyceride form); and (iv) fish
oil group (1.33 g EPA and 0.95 g DHA/d as free fatty acids) for 14 wk. The fatty acid composition of plasma lipids, platelets,
and erythrocyte membranes was analyzed by gas chromatography. The subjects kept 4-d food records four times during the study
to estimate the intake of nutrients. In the fish diet, in DHA oil, and in fish oil groups, the amounts of n-3 fatty acids
increased and those of n-6 fatty acids decreased significantly in plasma lipid fractions and in platelets and erythrocyte
membranes. A positive relationship was shown between the total n-3 polyunsaturated fatty acids (PUFA) and EPA and DHA intake
and the increase in total n-3 PUFA and EPA and DHA in all lipid fractions analyzed. DHA was preferentially incorporated into
phospholipid (PL) and triglyceride (TG) and there was very little uptake in cholesterol ester (CE), while EPA was preferentially
incorporated into PL and CE. The proportion of EPA in plasma lipids and platelets and erythrocyte membranes increased also
by DHA supplementation, and the proportion of linoleic acid increased in platelets and erythrocyte membranes in the DHA oil
group as well. These results suggest retroconversion of DHA to EPA and that DHA also interferes with linoleic acid metabolism. 相似文献
90.
This study proposes an operational way of computing the amenity value of a forest area that consists of several stands or compartments. Such a method produces an amenity index suitable for numerical optimization. With this method of computation, amenity is divided into scenic and recreation values. Scenic value of the forest depends on the visibility, area, and scenic beauty score of different compartments. Recreation value of the forest is a weighted mean of variety and the area-weighted mean recreation value of compartments. Variety is described by the total length of boundaries between distinctly different compartments. Recreation value of a compartment is the product of accessibility and recreation score of the compartment. Recreation and scenic beauty scores are computed from stand characteristics using empirical models. The study describes a complete planning system that uses the developed amenity index as a decision criterion, and relates a case study to illustrate the effect of amenity objective on choice of treatments for compartments. 相似文献