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1.
Salminen JP 《Journal of chemical ecology》2003,29(6):1289-1305
In this study, I investigated the effects of different methods of sample drying and storage, and the choice of extraction solvent and analysis method on the concentrations of 14 individual hydrolyzable tannins (HTs), and insoluble ellagitannins in birch (Betula pubescens) leaves. Freeze- and vacuum-drying of birch leaves were found to provide more reliable results than air- or oven-drying. Storage of leaves at –20C for 3 months before freeze-drying did not cause major changes in tannin content, although levels of 1,2,3,4,6-penta-O-galloylglucose and isostrictinin were altered. Storage of dried leaf material at –20C is preferred because 1 year storage of freeze-dried leaves at 4C and at room temperature decreased the concentration of the pedunculagin derivative, one of the main ellagitannins of birch. Furthermore, storage at room temperature increased the levels of isostrictinin and 2,3-(S)-HHDP-glucose, indicating possible HT catabolism. Of the extraction solvents tested, aqueous acetone was superior to pure acetone, or aqueous or pure methanol. The addition of 0.1% ascorbic acid into 70% acetone significantly increased the yield of ellagitannins, presumably by preventing their oxidation. By comparing the conventional rhodanine assay and the HPLC–ESI-MS assay for quantification of leaf galloylglucoses, the former tends to underestimate total concentrations of galloylglucoses in birch leaf extract. On the basis of the outcomes of all the method and solvent comparisons, their suitability for qualitative and quantitative analysis of plant HTs is discussed, emphasizing that each plant species, with its presumably unique HT composition, is likely to have a unique combination of ideal conditions for tissue preservation and extraction. 相似文献
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We consider the quantum optical eight-port homodyne detection scheme in the case that each of the associated photon detectors is assigned with a different quantum efficiency. We give a mathematically rigorous and strictly quantum mechanical proof of the fact that the measured observable (positive operator measure) in the high-amplitude limit is a smearing of the covariant phase space observable related to the ideal measurement, that is, the measurement performed with fully efficient detectors. The result is proved for an arbitary parameter field. Furthermore, we investigate some properties of the measured observable. In particular, we show that detector inefficiencies do not affect the observable's ability to distinguish between different states. 相似文献
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Tapio Eeva Samuli Helle Juha-Pekka Salminen Harri Hakkarainen 《Journal of chemical ecology》2010,36(6):608-613
Dietary carotenoids are important pigments, antioxidants, and immune-stimulants for birds. Despite recent interest in carotenoids
in bird ecology, we know surprisingly little about the carotenoid content of invertebrates consumed by birds. We compared
carotenoid (lutein, β-carotene, and total) concentrations in invertebrates brought to nestlings by two insectivorous passerines,
the great tit, Parus major and the pied flycatcher, Ficedula hypoleuca. We also compared carotenoid levels between environments that were either polluted by heavy metals or were not polluted,
because the carotenoid-based plumage color of P. major nestlings is affected by environmental pollution. Lepidopterans were the most carotenoid-rich food items and contained the
largest proportion of lutein. There were no differences in carotenoid concentrations in the food items of the two bird species
but P. major nestlings obtained more carotenoids from their invertebrate diet than F. hypoleuca nestlings because the P. major diet had a higher proportion of lepidopteran larvae. In polluted areas, P. major nestlings consumed lower levels of dietary carotenoids than in unpolluted areas because of temporal differences in caterpillar
abundance between polluted and unpolluted sites. Our study suggests that pollution-related difference in nestling plumage
color in P. major is related to varying dietary proportion of lutein-rich food items rather than pollution-related variation in insect carotenoid
levels. 相似文献
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SymbolChat: A flexible picture-based communication platform for users with intellectual disabilities
Tuuli Keskinen Tomi Heimonen Markku Turunen Juha-Pekka Rajaniemi Sami Kauppinen 《Interacting with computers》2012,24(5):374-386
Persons with intellectual disabilities benefit from participating in the modern information society, especially the World Wide Web, social media and Internet-mediated communication services. Although several computer-based prototypes and commercial systems have been introduced for accessible in-person communication, currently few applications and services exist to support synchronous remote communication for this user group. We introduce SymbolChat, a software platform that supports the creation of multimodal communication applications utilizing picture-based instant messaging. End users and their support personnel can customize the input and output features of the application based on their individual needs and abilities. The interaction is based on touchscreen input and speech output using speech synthesis technology. The SymbolChat platform was developed together with the prospective end users and practitioners in the field of special needs care.We evaluated the prototype application in a field study with nine users with varying degrees of intellectual and other disabilities. The results clearly indicate that the participants were able to express themselves in spontaneous communication using a large-scale picture-based vocabulary (around 2000 symbols) even without prior training in the use of symbols. This finding was supported in the constructive feedback gathered from professionals working in the area. We also successfully applied methodology from other settings, such as child-computer interaction to evaluate interaction in this challenging context.Overall, the results show that social inclusion for people with intellectual disabilities can be improved with customizable communication tools. The implemented communication platform forms a solid basis for further improvements and new communication services. In addition, we found that users with motor impairments would greatly benefit from alternative input and output methods for symbol browsing and selection. 相似文献
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Heikki Kallio Saska Tuomasjukka Anu Johansson Raija Tahvonen Niina Nieminen Olli Sjvall Juha‐Pekka Kurvinen Hanna Kivini 《European Journal of Lipid Science and Technology》2005,107(2):101-106
Currant oils have special health properties due to their moderate contents of α‐linolenic, γ‐linolenic and stearidonic acids. The distribution of fatty acids (FA) in the triacylglycerols (TAG) may affect the beneficial effects. Seed oils of wild northern red currant (NRC) (Ribes spicatum L.) from Northern Finland and of wild alpine currant (AC) (R. alpinum L.) from the South‐West coast of Finland were investigated. The purified TAG were analysed by tandem mass spectrometry by applying the ammonia negative ion chemical ionisation – collision‐induced dissociation method. Molecular weight fractions rich in C18:3 FA and C18:4 FA were investigated. Of the total oil, the molecular weight species 54:7 (ACN:DB), 54:8 and 54:9 were more abundant in NRC than in AC, being 21.0%, 15.8%, 7.4% and 16.2%, 11.2%, 4.8%, respectively (p <0.05). The species 52:6 was more abundant in AC (3.1%) than in NRC (2.6%) (p <0.05). The preferential order of FA to be in the sn‐2 position in both berries was typically C18:1 > C18:2 > C18:4 > C18:3. No difference was observed between relative locations of C16:0 FA and C18:3 FA in either of the oils. Within the TAG consisting of FA combinations C18:3/C18:3/C18:1 (54:7), C18:1 was more preferentially in the sn‐2 position (p <0.05) in AC (93.2%) than in NRC (74.6%), and in the case of C18:3, the preference was vice versa. Within the molecular weight species 54:9, FA combination C18:4/C18:3/C18:2, linoleic acid preferentially occupied the secondary position (p <0.005) in both berries, and the proportion of the TAG regioisomer pair sn‐C18:3‐C18:4‐C18:2 + sn‐C18:2‐C18:4‐C18:3 was more abundant (30.2%) in NRC than in AC (15.3%). Within the TAG species 52:6, proportions of all the existing combinations, C16:0/C18:3/C18:3, C16:0/C18:4/C18:2 and C16:1/C18:3/C18:2, varied between the two berry species (p <0.005). 相似文献
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Erkka Haapasalo Teiko Heinosaari Juha-Pekka Pellonp?? 《Quantum Information Processing》2012,11(6):1751-1763
Quantum measurements are mathematically described by positive operator valued measures (POVMs). Concentrating on finite dimensional systems, we show that one can limit to extremal rank-1 POVMs if two simple procedures of mixing and relabeling are permitted. We demonstrate that any finite outcome POVM can be obtained from extremal rank-1 POVMs with these two procedures. In particular, extremal POVMs with higher rank are just relabelings of extremal rank-1 POVMs and their structure is therefore clarified. 相似文献
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Rintala E Pitkänen JP Vehkomäki ML Penttilä M Ruohonen L 《Yeast (Chichester, England)》2007,24(2):129-136
The enzyme glyoxylate reductase reversibly reduces glyoxylate to glycolate, or alternatively hydroxypyruvate to D-glycerate, using either NADPH or NADH as a co-factor. The enzyme has multiple metabolic roles in different organisms. In this paper we show that GOR1 (ORF YNL274c) encodes a glyoxylate reductase and not a hydroxyisocaproate dehydrogenase in Saccharomyces cerevisiae, even though it also has minor activity on alpha-ketoisocaproate. In addition, we show that deletion of the glyoxylate reductase-encoding gene leads to higher biomass concentration after diauxic shift. 相似文献
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Plants have been suggested to have an immunological memory comparable to animals. The evidence for this, however, is scarce.
In our study with the mountain birch—Epirrita autumnata system, we demonstrated that birches exposed as long as 5 yr to feeding of E. autumnata larvae (delayed induced resistance, DIR), responded more strongly to a new challenge than trees without an herbivory history.
Pupal weights remained lower, and the duration of the larval period was prolonged in the DIR trees, although immunity, measured
as an encapsulation rate, was not affected. We further demonstrated that the effects of birch phenolics on performance of
E. autumnata were different in the exposed (DIR) trees from naive control trees, although we found only one significant change in chemistry.
The quercetin:kaemferol ratio was increased in DIR trees, suggesting that herbivory caused oxidative stress in birches. In
DIR trees, phenolics, especially hydrolyzable tannins (HTs), affected pupal weights negatively, whereas in control trees,
the effects were either nonsignificant or positive. HTs also prolonged the duration of the larval period of females, whereas
peroxidase (POD) activity prolonged that of males. We suggest that the causal explanation for the induced resistance was an
enhanced oxidation of phenolic compounds from the DIR trees in the larval digestive tract. Phenolic oxidation produces semiquinones,
quinones, free radicals, and ROS, which may have toxic, antinutritive, and/or repellent properties against herbivores. 相似文献