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21.
Genetic diversity of phalaris arundinacea populations in relation to river regulation in the Merkys basin,Lithuania 下载免费PDF全文
N. O. Anderson L. Jocienė E. Krokaitė T. Rekašius A. Paulauskas E. Kupčinskienė 《河流研究与利用》2018,34(4):300-309
During the 1950s–1960s, the Merkys river basin, the largest protected area of Lithuania, underwent severe anthropogenic regulations. Within the Baltic States, the genetic diversity of Phalaris arundinacea populations is unknown and how they might be affected by anthropogenic activities such as river regulation. The objectives of this study were to compare molecular parameters (SSRs or microsatellite loci) within and among populations from natural river fragments with populations from regulated river parts. Study populations have greater genetic diversity within, rather than among, populations. The upstream portion of the Merkys basin populations had lower genetic diversity compared with further downstream. The mean number of polymorphic SSR loci was lower for populations from regulated parts of the river basin compared with natural ones. Main principle coordinate analysis revealed populations of regulated rivers at marginal positions. Bayesian clustering showed that current populations are admixtures of 3 distinct genetic groups, based on STRUCTURE analysis (K = 3 groupings) in geographic subdivisions of (a) downstream populations (Var?n?, Verseka, Upper Grūda, Lower Grūda, Upper Merkys, Lower Merkys), (b) upstream populations (Upper ?al?ia, Ber??, Lower ?al?ia, Visin?ia, Lower ?altyk??ia, Nedil?), and (c) the 2 regulated sites in the distinct geographic area of Taurupis and Upper ?altyk??ia. P. arundinacea in the Merkys river basin does not all belong to a single, random‐mating population encompassing its tributaries or among populations across its geographic scales. In several instances, river regulation might impair the genetic diversity of P. arundinacea populations. 相似文献
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Lucia B. Chisari Akvilė Mockevičiūtė Sterre K. Ruitenburg Lian van Vemde Ellen M. Kok Tamara van Gog 《Journal of Computer Assisted Learning》2020,36(4):569-579
Eye movement modelling examples (EMMEs) are instructional videos of a model's demonstration and explanation of a task that also show where the model is looking. EMMEs are expected to synchronize students' visual attention with the model's, leading to better learning than regular video modelling examples (MEs). However, synchronization is seldom directly tested. Moreover, recent research suggests that EMMEs might be more effective than ME for low prior knowledge learners. We therefore used a 2 × 2 between-subjects design to investigate if the effectiveness of EMMEs (EMMEs/ME) is moderated by prior knowledge (high/low, manipulated by pretraining), applying eye tracking to assess synchronization. Contrary to expectations, EMMEs did not lead to higher learning outcomes than ME, and no interaction with prior knowledge was found. Structural equation modelling shows the mechanism through which EMMEs affect learning: Seeing the model's eye movements helped learners to look faster at referenced information, which was associated with higher learning outcomes. 相似文献
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The interaction between Pd2+ ions and Cu2-xS coating formed by three cycles and containing ~30 at.% of elementary S has been investigated by the methods of cyclic voltammetry and photoelectron spectroscopy (one cycle of coating formation includes treatment of the surface with Cu(I)+Cu(II) ammoniate solution, hydrolysis of the adsorbed copper compounds and sulphidation of copper oxygen compounds in Na2Sn solution). After exposure of such a coating to Pd2+ ions (1.7 mM PdCl2’ pH-2), an exchange as well as a redox interaction between the coating components and Pd2+ ions has been shown to occur. Due to this the amount of copper in the coating decreases from 2 to 4 times and that of sulphur from 1.5 to 5 times. The coating modified in such a way has been found to contain up to 75 at.% of palladium, ~90% of it being in a metallic state.It has been determined that at the beginning So is bound into a soluble compound:2Pd2+ + So + 3H2O → 2Pdo + H2SO3 + 4H+.The Cu2S present in the coating is considered to interact with Pd2+, with the formation of Pd0 and CuPdS2’, while CuS reacts most likely according to the reaction:CuS + 3Pd2+ + 3H2O → 3Pdo; + H2SO3 + Cu2+ + 4H+.The Cu2-xS +So coating formed on a dielectric and modified with Pd2+, contrary to the initial Cu2-xS +So coating, can be plated with copper from any electrolyte for copper deposition. 相似文献
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E. Griškonis A. Šulčius N. Žmuidzinavičienė 《Journal of Applied Electrochemistry》2014,44(10):1117-1125
The influence of the bath temperature on composition, current efficiency, structure, morphology, internal stresses and microhardness of Mn coatings obtained from manganese-ammonium sulphate electrolyte with 2.20 mM of Te(VI) additive at the current density of 15 A dm?2 was investigated. It has been found that with rising of the bath temperature from 20 to 80 °C the current efficiency increases from 37 to 71 %, the total concentration tellurium in the deposits increases from 0.9 to 1.6 wt% and the average size of crystallites of the coatings declines approx. from 24 to 15 nm. The structure of Mn coatings changes from the mixture of α-Mn and β-Mn phases at the lower temperatures to α-Mn phase at higher temperatures. Large tensile stresses (from 76 to 106 MPa) were determined for the Mn coatings with the thickness of 1.5–2.0 μm obtained at the initial stage of the deposition process. 相似文献
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Vitalija Rubežienė Aušra Abraitienė Julija Baltušnikaitė-Guzaitienė Sandra Varnaitė-Žuravliova Audronė Sankauskaitė Žilvinas Kancleris 《纺织学会志》2018,109(3):358-367
This study presents the investigation of electrically conductive fabrics with low resistivity, coated with formulation containing the conjugated polymer system – poly(3,4-ethylenedioxythiophene)-polystyrene sulphonate (PEDOT-PSS). The samples of fabrics were coated with PEDOT-PSS, using a screen printing method, by different patterns or coating their surface fully with different coating deposit. Methods for measurement of electrostatic properties, reflection and transmission as well as the assessment of electromagnetic radiation (EMR) shielding effectiveness were used for the characterization of electrical properties of developed samples. EMR shielding properties were investigated within 2–12 GHz frequency bands. The highest attenuation of the electromagnetic energy among tested fabrics was obtained on the fabrics fully coated with paste and it depended on deposit considerably. The influence of distribution and deposit of conductive coating on shielding effectiveness of textiles were determined. Correlation between shielding effectiveness and electrostatic properties of developed coated fabrics was also discussed. Electrical properties of samples coated with formulation containing PEDOT-PSS were compared with these of fabrics with metalized yarns, developed by us earlier. The results of EMR shielding measurements showed that fabrics coated with the paste containing conductive polymer system compared to fabrics with in-weaved conductive metalized yarns have certain advantages as EMR shields. 相似文献
28.
Jurga Sakalauskaitė Pranas Viskelis Edita Dambrauskienė Sandra Sakalauskienė Giedrė Samuolienė Aušra Brazaitytė Pavelas Duchovskis Dalia Urbonavičienė 《Journal of the science of food and agriculture》2013,93(6):1266-1271
BACKGROUND: The effects of short‐term ultraviolet B (UV‐B) irradiation on sweet basil (Ocimum basilicum L. cv. Cinnamon) plants at the 3–4 leaf pair and flowering stages were examined in controlled environment growth chambers. Plants were exposed to 0 (reference), 2 and 4 kJ UV‐B m?2 day?1 over 7 days. RESULTS: Exposure of basil plants to supplementary UV‐B light resulted in increased assimilating leaf area, fresh biomass and dry biomass. Stimulation of physiological functions in young basil plants under either applied UV‐B dose resulted in increased total chlorophyll content but no marked variation in carotenoid content. At the flowering stage the chlorophyll and carotenoid contents of basil were affected by supplementary UV‐B radiation, decreasing with enhanced UV‐B exposure. Both total antioxidant activity (2,2‐diphenyl‐1‐picrylhydrazyl free radical assay) and total phenolic compound content were increased by UV‐B light supplementation. Young and mature basil plants differed in their ascorbic acid content, which was dependent on UV‐B dose and plant age. UV‐B radiation resulted in decreased nitrate content in young basil plants (3–4 leaf pair stage). CONCLUSION: These results indicate that the application of short‐exposure UV‐B radiation beneficially influenced both growth parameters and biochemical constituents in young and mature basil plants. © 2012 Society of Chemical Industry 相似文献
29.
J. Požela K. Požela V. Jucienė A. Sužiedėlis A. S. Shkolnik S. S. Mikhrin V. S. Mikhrin 《Semiconductors》2009,43(12):1590-1596
The scattering rate of electrons in a quantum well by localized polar optical and interface phonons is considered. The dependence of the force of the electron-phonon interaction on the frequency of optical phonons in materials of the heterostructure forming the electron and phonon quantum wells is determined. It is shown that, by varying the composition of semiconductors forming the quantum well and its barriers, it is possible to vary the scattering rates of electrons by a factor of several times. The scattering rates of electrons by polar optical phonons are calculated depending on the fractions In x and In y in the composition of semiconductors forming the In x Al1 ? x As/In y Ga1 ? y As quantum wells. Dependences of the mobility and saturated drift velocity of electrons in high electric fields and quantum wells In y Ga1 ? y As on the composition of the In x Al1 ? x As barriers introduced into quantum wells are determined experimentally. The electron mobility increases, while the saturated drift velocity decreases as the fraction of In x in the composition of barriers is increased. 相似文献
30.
ABSTRACT For the first time, the Cr–CeO2 / La2O3 composite has been electrochemically deposited in a sulphate Cr (III) bath with an oxalate complexing agent. XRD analysis revealed that incorporation of CeO2/La2O3 particles into the Cr matrix does not change its state and the Cr matrix remains fine-crystalline (crystallites size < 1?nm). The cross-section SEM and EDS analysis confirmed the incorporation of CeO2/La2O3 particles into the Cr matrix. The studies of the mechanical properties of the Cr–CeO2/La2O3 composite have shown that the hardness of the composite increases over that of the Cr deposit due to CeO2/La2O3 particles incorporation, while both the friction coefficient and wear rate decrease. The mechanism of CeO2/La2O3 nanoparticles incorporation into the Cr matrix has been discussed. 相似文献