Wyniki wyszukiwania - Biblioteka Nauki

1

Finite Element analysis for Edge-to-Edge Technique to Treat Post-Mitral Valve Repair Systolic Anterior Motion

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Zhong Q. , Zeng W. , Huang X. , Zhao X.

Acta of Bioengineering and Biomechanics

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2014

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tom Vol. 16, no. 4

3--12

EN

Systolic anterior motion of the mitral valve is an uncommon complication of mitral valve repair, which requires immediate supplementary surgical action. Edge-to-edge suture is considered as an effective technique to treat post-mitral valve repair systolic anterior motion by clinical researches. However, the fundamentals and quantitative analysis are vacant to validate the effectiveness of the additional edge-to-edge surgery to repair systolic anterior motion. In the present work, finite element models were developed to simulate a specific clinical surgery for patients with posterior leaflet prolapse, so as to analyze the edge-to-edge technique quantificationally. The simulated surgery procedure concluded several actions such as quadrangular resection, mitral annuloplasty and edge-to-edge suture. And the simulated results were compared with echocardiography and measurement data of the patients under the mitral valve surgery, which shows good agreement. The leaflets model with additional edge-to-edge suture has a shorter mismatch length than that of the model merely under quadrangular resection and mitral annuloplasty actions at systole, which assures a better coaptation status. The stress on the leaflets after edge-to-edge suture is lessened as well.

2

100%

Cheng D. , Zhong Q. , Wang G.

Polish Journal of Ecology

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2009

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tom Vol. 57, nr 3

441-449

EN

Metabolic theory of ecology predicts a 3/4 power relationship between annual productivity P[T] and body size M[T] (i.e., P [is proportional to] M[^3/4]), which has important implications to estimates of carbon fluxes, ecosystem health, global carbon budgets, and a variety of other phenomena. To test this prediction, we examined a large dataset for Chinese forests. Such dataset covers six major forest biomes and a total of 17 forest types grown across a range of annual temperature (-6.6 to 25.2[degrees]C), mean annual rainfall (27 to 2989 mm), elevation (10 to 4240 m a.s.l.), and stand age (3 to 350 yrs.). Reduced major axis (RMA) regression analyses were used to compare the P[T] versus M[T] scaling exponents and normalization constants (i.e., slopes and Y-intercepts of log-log linear relationships, respectively). Comparisons were made for ten different age-sequences (stand age ranges from 20 to 200 yrs). When stand age was less than 100 yrs, relationship of P[T] versus M[T] had similar scaling exponents ([alpha][RMA]>> 1.0), while the Y-intercepts decreased systematically. When stand age exceeded 140 yrs, scaling exponents decreased ([alpha][RMA] <0.86). Both the aboveground annual productivity and aboveground body size per individual tree (P[A] and M[A], respectively) showed the same behavior. We therefore conclude that the relationship of P[T] versus M[T] systematically declined with the stand age, and was inconsistent with the predictions of metabolic theory.

3

Optimization of microwave-assisted extraction of flavonoids from young barley leaves

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Gao T. , Min Z. , Fang Z. , Zhong Q.

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nr 1

EN

A central composite design combined with response surface methodology was utilized to optimise microwave-assisted extraction of flavonoids from young barley leaves. The results showed that using water as solvent, the optimum conditions of microwave-assisted extraction were extracted twice at 1.27 W g-1 microwave power and liquid-solid ratio 34.02 ml g-1 for 11.12 min. The maximum extraction yield of flavonoids (rutin equivalents) was 80.78±0.52%. Compared with conventional extraction method, the microwave-assisted extraction was more efficient as the extraction time was only 6.18% of conventional extraction, but the extraction yield of flavonoids was increased by 5.47%. The main flavonoid components from the young barley leaf extract were probably 33.36% of isoorientin-7-O-glueoside and 54.17% of isovitexin-7-O-glucoside, based on the HPLC-MS analysis. The barley leaf extract exhibited strong reducing power as well as the DPPH radical scavenging capacity.

4

Defferential response to paraquat induced oxidative stress in two rice cultivars on antioxidants and chlorophyll a fluorescnce

88%

Guo Z. , Huang M. , Lu S. , Yaqing Z. , Zhong Q.

Acta Physiologiae Plantarum

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2007

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tom 29

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nr 1

EN

The responses of antioxidative system and photosystem II photochemistry of rice (Oryza sativa L.) to paraquat induced oxidative stress were investigated in a chilling-tolerant cultivar Xiangnuo no. 1, and a chilling-susceptible cultivar, IR-50. Electrolyte leakage and malondialdehyde (MDA) content of Xiangnuo no. 1 were little affected by paraquat, but they increased in IR-50. After paraquat treatment, superoxide dismutase (SOD) activity remained high in Xiangnuo no. 1, while it declined in IR-50. Activities of catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) declined with oxidative stress in both cultivars, but Xiangnuo no. 1 had higher GR activity than IR-50. Under paraquat induced oxidative stress, ascorbic acid (AsA) and reduced glutathione (GSH) concentrations remained high in Xiangnuo no. 1, but decreased in IR-50. The results indicated that higher activities of SOD and GR and higher contents of AsA and GSH in Xiangnuo no. 1 under paraquat induced oxidative stress were associated with its tolerance to paraquat, while paraquat induced damage to IR-50 was related to decreased activities of SOD, APX and GR and contents of AsA and GSH. Fv/Fm, ΦPSII, and qP remained high in Xiangnuo no. 1, while they decreased greatly in IR-50 under paraquat induced oxidative stress.

5

Invariant allometric relationship between aboveand below-ground biomass along a moisture gradient in North-West China

88%

Cheng D. , Wang G. , Tang Q. , Li T. , Zhong Q.

Polish Journal of Ecology

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2009

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tom Vol. 57, nr 4

669-675

EN

Biomass allocation pattern is an important plant characteristic which influences how plants respond to abiotic and biotic heterogeneity. Prior studies indicate that above-ground biomass scales nearly isometrically with respect to below-ground biomass regardless of environment or phyletic affinity. However, such rule has been mostly tested with data on trees and usually without drought stress. Given the importance of this predicted relationship, it should be evaluated for a wider range of species and environmental conditions. Variations of the above- and belowground biomass (M[A] and M[R], respectively) were determined from five sites in north-west China, which compose a natural moisture gradient (aridity index ranging from 0.95 to 1.98). Model Type II regression protocols were used to compare the numerical values of M[A] vs M[R] scaling exponents (i.e. slopes of log-log linear relationships). The resulting five scaling exponents were indistinguishable and had a similar, nearly isometric slope (i.e. M[A] [is proportional to] M[R] [is approximately equal to] 1.0). Significant variation was observed in the Y-intercepts of the five regression curves, because of the absolute differences in M[A] or M[R]. These results support prior allometric theory, which reveals an isometric relationship between above- and below-ground biomass, and may provide a suitable method to estimate the regional below-ground biomass based on the direct aboveground measurements.

6

Environmental and Economic Dispatch Model for Smart Microgrid Based on Shuffled Frog Leap Algorithm Optimized by Random Nelder Mead

75%

Zhong Q. , Xue S. , Wang Z. , Duan J. , Zeng M. , Zhang G.

Przegląd Elektrotechniczny

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2013

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tom R. 89, nr 3b

147--151

EN

As more and more distributed generation resources are integrated into the grid through smart micro-grid, achieving a more economic and better responsive distributed generation dispatch is of great importance. Economic and environmental characteristics of distributed generation are synthetically combined in a dispatch model with objective function of minimum generation cost and emission cost in this paper, and also a novel algorithm Shuffled Frog Leap Algorithm (SFLA) optimized by random Nelder Mead (RNM) model was proposed to solve the economic and environmental problem. At last, the differences in generation cost and Computation time of RNM-SFLA, Genetic Algorithm (GA), Evolutionary Programming (EP) and Shuffled Frog Leap Algorithm (SFLA) are compared with a numerical example, verifying the feasibility and advancement of environmental and economic dispatch model based on RNM-SFLA.

PL

W artykule przedstawiono model przesyłu energii elektrycznej w systemie elektroenergetycznym, mający na celu minimalizację kosztów wytwarzania i przesyłu energii. Zaproponowano także nowy algorytm SFL (ang. Shuffled Frog Leap), który został zoptymalizowany metodą Nelder’aa-Mead’a. Algorytm ma zastosowanie w rozwiązywaniu zagadnień ekonomicznych i środowiskowych. Przeprowadzona została analiza porównawcza opisanego modelu.