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191.
[Pb0.961La0.012Ba0.015Sr0.012][Zr0.53Ti0.47]0.967-(h/2)Nb0.02Zn0.01MnhO3 (PLBSZZMNT) nano-ceramics where h = 0, 0.5. 1 and 1.5 mol% fabricated through solid state reaction method has been investigated
for phase formation, microstructure, density, dielectric and piezoelectric properties. X-ray diffraction studies indicated
that all the samples exhibited a single-phase perovskite tetragonal structure which had strongly intensified due to the acceptor
Mn content increment in the series. Our investigation with reference to isovalent (Ba2+ and Sr2+) on the A-site, pentavalent donor (Nb5+) and acceptor (Zn2+ and Mn4+) dopants on the B-site in PLZT perovskite with the stoichiometric compositional formulation tailored for dielectric and piezoelectric
properties has been clearly explained. As Mn concentration increased, the grain growth enhanced, and the inter-diffusion between
multiple ions promoted densification in the PLBSZZMNT nano-ceramics. TEM studies revealed an average particle size ranging
from 20 to 72 nm. Dielectric characterization revealed that the εRT enhanced till 1.5 mol% Mn (2946) while the Curie temperature and dielectric loss at room temperature (Tc and TanδRT) decreased, respectively. Mn doping in PLBSZZNT induced the piezoelectric parameters (kp = 0.567) and (d33 = 486 pC/N) till 1.5 mol% Mn. Thus, 1.5 mol% Mn modified PLBSZZNT exhibits optimum dielectric and piezoelectric properties,
which are suitable for possible sensor and actuator applications. 相似文献
192.
Event fairness and non-interleaving concurrency 总被引:1,自引:0,他引:1
Marta Z. Kwiatkowska 《Formal Aspects of Computing》1989,1(1):213-228
Event fairness suitable for non-interleaving concurrency is proposed. Fairness is viewed with respect to concurrency, rather than non-determinism, in the sense that no concurrent component of the system should be delayed indefinitely. Shields' asynchronous transition systems and Mazurkiewicz's traces have been used; the model gives rise to a partial order. A class of generalised notions of (weak, strong and unconditional) event fairness relative to progress requirements is derived. The weakest fairness notion in this class is shown to coincide with maximality with respect to the partial order over traces. 相似文献
193.
Francisco Perez-Sorrosal Marta Patiño-Martinez Ricardo Jimenez-Peris Bettina Kemme 《The VLDB Journal The International Journal on Very Large Data Bases》2011,20(6):841-865
The new vision of cloud computing demands scalable, available and autonomic software platforms in order to deploy applications and services accessible anywhere
and anytime. Multi-tier architectures are an important building block for many applications that are deployed in the cloud.
This paper presents a novel caching and replication infrastructure that facilitates the scalable and elastic deployment of
multi-tier architectures. Our Elastic SI-Cache is a novel multi-version cache that attains high performance and consistency in multi-tier systems. In contrast to most existing
caches, Elastic SI-Cache provides snapshot isolation coherently across all tiers. Furthermore, Elastic SI-Cache supports scalable
replication of the different tiers where replicas can be added or removed dynamically as needed, making the cache amenable
for cloud computing environments. Elastic SI-Cache has been implemented and integrated into an open source JEE application
server and its performance evaluated with the industrial benchmark SPECjAppServer. 相似文献
194.
A new approach is proposed to characterize polyampholytic gelatin hydrogels, cross-linked covalently with glutaraldehyde. An experimental methodology involving simple mechanical extension and compression and equilibrium swelling tests is developed to estimate relevant microstructural parameters and electrokinetic properties of this type of hydrogel, for different cross-linker to gelatin mass ratios. The polyampholytic cross-linked matrices are studied here in the framework of the rubber elasticity and thermodynamic swelling theories. The main purposes of this work are the estimations of average mesh size and toughness of the swollen hydrogels, and the determination of the feasibility of polyion complexation between cross-linked gelatin chains and bioactive macromolecules to be delivered through hydrogel biodegradation. 相似文献
195.
Marta Francisco Pablo Velasco Diego A. Moreno Cristina García-Viguera María Elena Cartea 《Food research international (Ottawa, Ont.)》2010,43(5):1455-1463
Cooking Brassica vegetables as a domestic processing method has a great impact on health-promoting bioactive compounds: glucosinolates (GLS), flavonoids, hydroxycinnamic acids, and vitamin C. In Galicia (NorthWestern Spain), one of the most consumed horticultural crops is Brassica rapa, by using the leaves (turnip greens) and the young sprouting shoots (turnip tops) in different culinary preparations. In order to determine the effect of cooking, on turnip greens and turnip tops, bioactive GLS, flavonoids, hydroxycinnamic acids and vitamin C were analysed and simultaneously determined. The level of retention of each individual compound after cooking procedures was evaluated in the edible organs, and also in the cooking water, in order to compare their composition to a fresh uncooked control. Steaming, conventional boiling, and high-pressure cooking, traditional processing methods of this kind of vegetables, were the three domestic processing methods used in this work. Results showed that total GLS and phenolics were significantly affected by the cooking procedure and the loss rate varied among individual compounds. Steaming was the method that better preserved GLS and phenolic compounds. Conventional boiling and high-pressure cooking methods presented similar rate of losses of total GLS content (64%) and total phenolic content (more than 70%). Degradation among glucosinolate classes, aliphatic or indolic, was similar. The total flavonoids lost in turnip greens were 64% and 67% for conventional boiling and high-pressure, respectively. The main losses were caused by leaching into the cooking water. The concentration of vitamin C suffered a drastic loss in the process of sample handling and after cooking. Despite the fact that any cooking procedure affected negatively the nutritional composition of the turnip greens and tops, our results showed high retentions of individual compounds in steaming, and the lowest retentions were obtained in the traditional high-pressure cooking. High retention of health-promoting compounds in the cooking water should be considered for increasing the intake of properties of B. rapa. 相似文献
196.
Jolanta Skalska Piotr Bednarczyk Marta Piwońska Bogusz Kulawiak Grzegorz Wilczynski Krzysztof Do?owy Alexei P. Kudin Wolfram S. Kunz Adam Szewczyk 《International journal of molecular sciences》2009,10(3):1104-1120
The mitochondrial response to changes of cytosolic calcium concentration has a strong impact on neuronal cell metabolism and viability. We observed that Ca2+ additions to isolated rat brain mitochondria induced in potassium ion containing media a mitochondrial membrane potential depolarization and an accompanying increase of mitochondrial respiration. These Ca2+ effects can be blocked by iberiotoxin and charybdotoxin, well known inhibitors of large conductance potassium channel (BKCa channel). Furthermore, NS1619 – a BKCa channel opener – induced potassium ion–specific effects on brain mitochondria similar to those induced by Ca2+. These findings suggest the presence of a calcium-activated, large conductance potassium channel (sensitive to charybdotoxin and NS1619), which was confirmed by reconstitution of the mitochondrial inner membrane into planar lipid bilayers. The conductance of the reconstituted channel was 265 pS under gradient (50/450 mM KCl) conditions. Its reversal potential was equal to 50 mV, which proved that the examined channel was cation-selective. We also observed immunoreactivity of anti-β4 subunit (of the BKCa channel) antibodies with ~26 kDa proteins of rat brain mitochondria. Immunohistochemical analysis confirmed the predominant occurrence of β4 subunit in neuronal mitochondria. We hypothesize that the mitochondrial BKCa channel represents a calcium sensor, which can contribute to neuronal signal transduction and survival. 相似文献
197.
Nivia Maria Streit Luisa Helena Rychecki Hecktheuer Marta Weber do Canto Carlos Augusto Mallmann Letícia Streck Thaylise Vey Parodi Liana Pedrolo Canterle 《Food chemistry》2007,102(3):560-564
Erva-mate (Ilex paraguariensis St. Hil.) is a native species from temperate regions of South America, such as Brazil, Paraguay, and Argentina, that is consumed as a beverage known as mate. The objective of this research was to determine the content of caffeic acid, catechin, chlorogenic acid, caffeine, and gallic acid in mate to explain their influence in beverage taste and sensory differences between native and reforested plants, as well as between beverages from plants of different regions of Brazil (Santa Catarina and Rio Grande do Sul states). Compounds were determined by HPLC and results were related to a sensory evaluation performed by trained tasters. Tasters considered the beverage from reforested plants to be more bitter than the beverage from native plants. Beverages from reforested plants had significantly higher caffeic acid and lower catechin, chlorogenic acid, caffeine, and gallic acid content than native plants. Beverages from plants of Santa Catarina state had significantly higher catechin, caffeine, and gallic acid content than plants from Rio Grande do Sul state. 相似文献
198.
Effect of the long-term intake of an egg white hydrolysate on the oxidative status and blood lipid profile of spontaneously hypertensive rats 总被引:1,自引:0,他引:1
María A. Manso Marta Miguel Jeanne Even Rosario Hernández Amaya Aleixandre Rosina López-Fandiño 《Food chemistry》2008
This paper examines the effects of the long-term consumption of egg white hydrolysed with pepsin (hEW) on the antioxidant status and lipid profile of spontaneously hypertensive rats (SHR). The antioxidant capacity was measured by the oxygen radical absorbance capacity (ORAC) and the oxidative status by the malon-dialdehyde (MDA) assay. The lipid profile was analysed spectrophotometrically. The radical-scavenging capacity of the plasma was increased and the MDA concentration in the aorta was decreased in the SHR treated with 0.5 g/kg/day of hEW. Our findings indicate that hEW played an important role in antioxidative defence of SHR and exerted a beneficial effect on the lipid profile, lowering triglycerides and total cholesterol without changing HDL levels. Therefore, hEW may be useful to prevent or reverse abnormalities associated with the metabolic syndrome and its complications, such as hypertension, oxidative stress and hyperlipidemia. 相似文献
199.
Coulson Seana; Federmeier Kara D.; Van Petten Cyma; Kutas Marta 《Canadian Metallurgical Quarterly》2005,31(1):129
Researchers using lateralized stimuli have suggested that the left hemisphere is sensitive to sentence-level context, whereas the right hemisphere (RH) primarily processes word-level meaning. The authors investigated this message-blind RH model by measuring associative priming with event-related brain potentials (ERPs). For word pairs in isolation, associated words elicited more positive ERPs than unassociated words with similar magnitudes and onset latencies in both visual fields. Embedded in sentences, these same pairs showed large sentential context effects in both fields. Small effects of association were observed, confined to incongruous sentences after right visual hemifield presentation but present for both congruous and incongruous sentences after left visual hemifield presentation. Results do not support the message-blind RH model but do suggest hemispheric asymmetries in the use of word and sentence context during real-time processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
200.
Carina A. Emilio Raquel Gettar Marta I. Litter 《Journal of Applied Electrochemistry》2005,35(7-8):733-740
TiO2-heterogeneous photocatalysis of nitrilotriacetic acid (NTA) at pH 2.5 was studied to establish the kinetic regime and the
reaction mechanism. Pure Degussa P-25 and Hombikat UV100 commercial samples were compared. A Langmuirian behavior was observed
over P-25. Platinization of the Hombikat sample (0.5 wt.%) caused an important increase on the photocatalytic rate with a
change in the kinetics from zero order in the pure precursors to first order in the platinized sample. The nature of the intermediates
and their evolution with time were compared on all systems. Glycine, iminodiacetic and oxamic acids have been identified in
different proportions, together with ammonium and glycolic acid, depending on the catalyst used. The rapid depletion of NTA
was not accompanied by a corresponding total organic carbon (TOC) reduction, but 84% of TOC decrease was obtained on P25 after
24 h, a very reasonable result for refractory compounds. A detailed mechanism is proposed for the photocatalytic reaction,
suggested to be the same over the three catalysts here tested. 相似文献