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51.
Laitinen J Julkunen-Tiitto R Rousi M Heinonen J Tahvanainen J 《Journal of chemical ecology》2005,31(10):2243-2262
This study investigates variation in the secondary chemistry of the bark of three closely related, winter-dormant species
of white birch (Betula resinifera, B. pendula, and B. platyphylla) at different ontogenetic stages by using different plant parts (top and base). The experimental birches were grown for 4 years
in two growing conditions (pot and field) at different nutrient levels. There was considerable species-specific quantitative
and qualitative variation in the secondary chemicals in bark, but this was also affected by fertilization and the age of the
plant. In general, there was greater chemical diversity in saplings than in seedlings. The study revealed three new components,
secoisolariciresinol 9-O-β-glucopyranoside and two of its derivatives, that have not been reported previously for the bark of white birches. Principal
component analysis showed that the species studied had a similar chemical composition at the juvenile stage, but as the plants
grew, they became more clearly differentiated, which indicates that the species of older plants can be identified by chemotaxonomy.
Evidently, the secondary chemistry of birches is under genetic control, but it is affected by properties of growing conditions
and ontogeny.
Electronic Supplementary Material Supplementary material to this paper is available in electronic form at 相似文献
52.
Nikolaos Nikolaou Panagiotis Dimitrakis Pascal Normand Vassilios Ioannou-Sougleridis Konstantinos Giannakopoulos Konstantina Mergia Kaupo Kukli Jaakko Niinistö Mikko Ritala Markku Leskelä 《Solid-state electronics》2012
In this work we report the performance of the SiO2/Si3N4/HfO2 and SiO2/Si3N4/ZrO2 stacks with emphasis on the influence of atomic layer deposition chemistry used for forming the HfO2 and ZrO2 blocking layers. Two Hf precursors were employed – tetrakis(ethylmethylamino)hafnium (TEMAH) and bis(methylcyclopentadienyl)methoxymethyl hafnium (HfD-04). For ZrO2, tetrakis(ethylmethylamino)zirconium (TEMAZ) and bis(methylcyclopentadienyl)methoxymethyl zirconium (ZrD-04) were used as metal precursors. Ozone was used as the oxygen source. The structural characteristics of the stacks were examined by transmission electron microscopy and grazing incidence X-ray diffraction. The electrical properties of the stacks were studied using platinum-gated capacitor structures. The memory performance of the stacks was evaluated by write/erase (W/E) measurements, endurance and retention testing. Endurance measurements revealed the most important difference between the stacks. The films grown from TEMAH and TEMAZ could withstand a significantly higher number of W/E pulses (>3 × 105 in the 10 V/?11 V, 10 ms regime), in comparison to the stacks made from HfD-04 and ZrD-04 precursors (<5 × 103 W/E cycles). This difference in endurance characteristics is attributed mainly to the different deposition temperatures suited for these two precursors and the nature of the layer formed at the Si3N4/HfO2 and the Si3N4/ZrO2 interfaces. 相似文献
53.
Innovation, knowledge spillovers and local labour markets 总被引:3,自引:0,他引:3
Abstract. This article investigates the role played by geography in the promotion of innovation. In order to examine these issues we employ empirical data from Finland in order to test the extent to which the variety and nature of face-to-face contacts affects the innovation performance of the firm. In addition, we then also control for the geographical mobility of the labour employed by the firm. This allows us to identify the different roles that the geography of knowledge spillovers and exchanges and the geography of labour markets play in the innovation process. 相似文献
54.
55.
Dick Danielle M.; Viken Richard; Purcell Shaun; Kaprio Jaakko; Pulkkinen Lea; Rose Richard J. 《Canadian Metallurgical Quarterly》2007,116(1):213
Although there is a substantial literature on the role of parenting in adolescent substance use, most parenting effects have been small in magnitude and studied outside the context of genetically informative designs, raising debate and controversy about the influence that parents have on their children (D. C. Rowe, 1994). Using a genetically informative twin-family design, the authors studied the role of parental monitoring on adolescent smoking at age 14. Although monitoring had only small main effects, consistent with the literature, there were dramatic moderation effects associated with parental monitoring: At high levels of parental monitoring, environmental influences were predominant in the etiology of adolescent smoking, but at low levels of parental monitoring, genetic influences assumed far greater importance. These analyses demonstrate that the etiology of adolescent smoking varies dramatically as a function of parenting. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
56.
57.
Antti Rostedt Anssi Arffman Kauko Janka Jaakko Yli-Ojanperä Jorma Keskinen 《Aerosol science and technology》2014,48(10):1022-1030
The Pegasor PPS-M sensor is an electrical aerosol sensor based on diffusion charging and current measurement without particle collection. In this study, the role and effect of each component in the instrument is discussed shortly and the results from a thorough calibration measurements are presented. A comprehensive response model for the operation of the PPS-M sensor was developed based on the calibration results and computational fluid dynamics (CFD) modeling results. The obtained response model, covering the effects of the particle charger, the mobility analyzer, and both diffusion and inertial losses, was tested in the laboratory measurements with polydisperse test aerosols, where a good correlation between the model and the measured results was found.
Copyright 2014 American Association for Aerosol Research 相似文献
58.
Helka Juvonen Maria Smolander Harry Boer Jaakko Pere Johanna Buchert Jouko Peltonen 《应用聚合物科学杂志》2011,119(4):2205-2213
The use of renewable materials as barrier material is currently intensively investigated. Biopolymers such as polysaccharides, lipids, and proteins have been studied as barrier materials. Protein‐based films often possess good gas barrier properties, but because of their hydrophilic nature the gas barrier properties are sensitive to humidity. The improvement of the properties of sodium caseinate barrier films in potential packaging applications was studied by investigating the effects of enzymatic treatment and plasticizer on the film properties. Oxidoreductases Trametes hirsuta laccase (ThL) and Trichoderma reesei tyrosinase (TrTyr) were compared with transglutaminase for crosslinking of the sodium caseinate molecules in the films and coatings. All of the studied enzymes were able to crosslink sodium caseinate. Film solubility tests, protein electrophoresis, contact angle measurements, and atomic force microscopy studies showed that TrTyr treatment results in sodium caseinate films and coatings with better overall properties compared to treatment with ThL. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
59.
The temperature effect (37–65 °C) on H2 production from glucose in an open-mixed culture bioreactor using an enrichment culture from a hot spring was studied. The dynamics of microbial communities was investigated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). At 45 and 60 °C the H2 production was the highest i.e. 1.71 and 0.85 mol H2/mol glucose, respectively. No H2 was produced at temperatures 50 and 55 °C. At 37–45 °C, H2 production was produced by butyrate type fermentation while fermentation mechanism changed to ethanol type at 60 °C. Clostridium species were dominant at 37–45 °C while at 50–55 °C and 60 °C the culture was dominated by Bacillus coagulans and Thermoanaerobacterium, respectively. In the presence of B. Coagulans the metabolism was directed to lactate production. The results show that the mixed culture had two optima for H2 production and that the microbial communities and metabolic patterns promptly changed according to changing temperatures. 相似文献
60.
Salvador Dueñas Helena Castán Héctor García Alfonso Gómez Luis Bailón Kaupo Kukli Jaakko Niinistö Mikko Ritala Markku Leskelä 《Microelectronic Engineering》2009,86(7-9):1689-1691
Electrical characterization of zirconium oxide (ZrO2) based metal-oxide-semiconductor (MOS) structures has been carried out. ZrO2 films have been atomic layer deposited (ALD) by using novel cyclopentadienyl-based precursors, which have recently revealed themselves as very adequate in terms of thermal stability and high permittivity of the dielectrics deposited. Our results demonstrate good quality of the films, especially when mixed alkylamido-cyclopentadienyl precursors are used on SiO2/Si substrates. Conduction mechanisms in these MIS capacitors were studied, with moderately or highly-doped silicon used as substrate. 相似文献