Wyniki wyszukiwania - Biblioteka Nauki

1

Construct DNA Symmetric Encryption Based on the Problem of Fragment stitching

100%

Zhang Y. , Zhang X. , Fu B. , He T.

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tom R. 89, nr 3b

4--6

EN

DNA cryptography is a new born information security field and have been the international frontier of cryptography emerged with the constantly invasion of traditional cryptography and improvement of research on DNA computing and bio-technology. The security of DNA cryptography is based on difficult biological problems which are unrelated with computing power and thus it is immune to current computer and even future quantum computers. In this paper, we study the difficult biological problem which is the key and basic part in designing of DNA encryption. After analysis of encoding of DNA and mechanism of symmetric encryption, we design a symmetric system using the technology of DNA digital coding and DNA fragment assembly. By implanting DNA secret fragment into the numerous plaintext ones, we destroy the key overlap phase of DNA fragment assembly, thus the normal assembly process cannot be accomplished. In this way, the safety of the encryption scheme is achieved.

PL

W artykule omówiono zagadnienie kodowania DNA i związanych z tym skomplikowanych procesów biologicznych, w odniesieniu do komercyjnych zastosowań. Z uwagi na duży postęp w badaniach nad DNA oraz rozwój klasycznej kryptografii, kodowanie DNA stało się nową, dostępną kategorią. Zaproponowana metoda implementacji tworzy bezpieczny schemat kodowania.

2

88%

Lu T. , Ma K. , Zhang Y. , Ni H. , Fu B.

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tom Vol. 57, nr 4

647-657

EN

Disturbance is considered to be one of the main factors influencing variations in species diversity. While many experimental and observational studies provide a good understanding of how disturbance maintains the [alfa]-diversity, we know little about how disturbance influences [beta]-diversity, and the effects of disturbance intensity on spatial species turnover are lacking. The aim of this paper is to evaluate the effects of disturbance on patterns of species similarity in wetland communities, and to identify how disturbance intensity affects the species similarity - distance relationship. In our study, four isolated wetland remnants under different agricultural drainage ditch densities were surveyed in Sanjiang Plain, Northeast China. Wetland disturbance was assessed by agricultural ditch densities, and species similarity was quantified by the Jaccard index. A simple measure of environmental distance was obtained by using water level and five soil variables, and a corresponding measure of geographical distance was made between pairs of plots from each site. Based on these data, we estimated rates of distance decay through regression of log-transformed compositional similarity against both environmental and geographical distance for pair-wise comparisons of wetland plots from each site. One key finding of our research is that disturbance intensity does influence the species similarity - distance relationship. At each site, species similarity decreased significantly with distance, and both effects of geographical and environmental distance were statistically significant. The results indicate that with disturbance intensity increasing, the distance decay rate decreases.

3

Species similarity - distance relationship in wetlands: effect of disturbance intensity

88%

Lu T. , Ma K. , Zhang Y. , Ni H. , Fu B.

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nr 4

647-657

EN

Disturbance is considered to be one of the main factors influencing variations in species diversity. While many experimental and observational studies provide a good understanding of how disturbance maintains the α-diversity, we know little about how disturbance influences β-diversity, and the effects of disturbance intensity on spatial species turnover are lacking. The aim of this paper is to evaluate the effects of disturbance on patterns of species similarity in wetland communities, and to identify how disturbance intensity affects the species similarity - distance relationship. In our study, four isolated wetland remnants under different agricultural drainage ditch densities were surveyed in Sanjiang Plain, Northeast China. Wetland disturbance was assessed by agricultural ditch densities, and species similarity was quantified by the Jaccard index. A simple measure of environmental distance was obtained by using water level and five soil variables, and a corresponding measure of geographical distance was made between pairs of plots from each site. Based on these data, we estimated rates of distance decay through regression of log-transformed compositional similarity against both environmental and geographical distance for pair-wise comparisons of wetland plots from each site. One key finding of our research is that disturbance intensity does influence the species similarity - distance relationship. At each site, species similarity decreased significantly with distance, and both effects of geographical and environmental distance were statistically significant. The results indicate that with disturbance intensity increasing, the distance decay rate decreases.

4

Electrophoretic behaviour and quantitative analysis of active components 6,7-dehydroroyleanone and taxoquinone extracted from Salvia deserta Schang

75%

Zhao Y. , Cao Q. , Chen X. , Hu Z. , Fu B. , Chang J.

Chemia Analityczna

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2000

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tom Vol. 45, No. 2

237-248

EN

This communication demonstrates that micellar electrokinetic chromatography (MEKC) can be convenient for the determination of minor active components 6,7-dehydro-royleanone and taxoquinone in the extract of the traditional Chinese medicinal herb. 6,7-Dehydroroyleanone and taxoquinone can be monitored selectively and sensitively at 254 nm within 8 min in the plant extract, using alfa-cyclodextrin (alfa-CD) as a MEKC modified. The concentration range was 5-500 ug ml-1 for 6,7-dehydroroyleanone and 2.5-750 ug ml-1 for taxoquinone with good linear correlation coefficients 0.9997 and 0.9989, respectively. It was found that 68.2 ug of 6,7-dehydroroyleanone and 12.5 ug of taxoquinone were contained in 1 g of Salvia deserta Schang roots. The inclusion of 6,7-dehydroroyleanone and taxoquinone with alfa-CD in capillary zone electrophoresis (CZE) was studied, and the inclusion constant logKCD were 4.1 and 3.2 for 6,7-dehydroroyleanone and taxoquinone, respectively.

PL

Wykazano, że metoda elektrokinetycznej chromatografii micelarnej (MEKC) może być zastosowana do oznaczania 6,7-dehydrorojleanonu i taksochinonu w ekstraktach surowców roślinnych. Oba biologicznie aktywne związki są ubocznymi składnikami ziół stosowanych w chińskiej medycynie tradycyjnej. Zastosowanie p-cyklodekstryn jako moodyfikatora, pozwala na selektywne oznaczenie obu związków ze znaczną czułością w ciągu 8 min przy 254 nm. Dla 6,7-dehydrorojleanonu i taksochinonu, w zakresie stężeń 5-500 ug ml-1 i 2.5-750 ug ml-1, otrzymano współczynniki korelacji odpowiednio -0.9997 i 0.9989. Stwierdzono, że l g korzeni Sahia deserta Schang zawiera 68.2 ug 6,7-dehydrorojleanonu i 12.5 ug taksochinonu. Za pomocą kapilarnej elektroforezy strefowej zbadano inkluzje obu związków z alfa-cyklodekstryną. Wyznaczono stałe inkluzji logKcD 4.1 i 3.2 odpowiednio dla 6,7-dehydrorojleanonu i taksochinonu.

5

Diversity and composition of wetland communities along an agricultural drainage ditch density gradient

75%

Lu T. , Ma K. , Fu B. , Zhang J. , LU Q. , Hudson S.

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tom Vol. 57, nr 1

113-123

EN

Agricultural drainage ditches are a reflection of the disturbance caused by agriculture and other human perturbations associated with agricultural activities, and the density of them can be seen as an important gradient reflecting local disturbance. However, no studies to date have examined the changes in wetland communities in relation to drainage ditch densities, yet such information is urgently needed for the conservation of wetland ecosystems facing intensive cultivation. In this paper, we inventoried 67 plots at four wetland mosaics with the ditch density values ranged 0-3.6 km km[^-2] in the Sanjiang Plain, and the species richness, composition and diversity were compared among those four sites. Linear regression was used to explore relationships between wetland community pattern and agricultural ditch density, and the results show that there is significant relationship (r[^2] = 0.56, P <0.001). The diversity comparisons show that there exist a clear negative relationship between ditch density and species diversity indices, and the species diversity did not differ greatly among sites, but species composition varied considerably. With increasing ditch density, an increasing loss of indigenous wetland species paralleled with an increasing incursion of upland species. Management implication from the drainage ditches is that the density of 1.2 km km[^-2] be the maximum value suitable for the protection of native wetlands in Sanjiang plain.