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2-Oxoamides based on long chain beta-amino acids were synthesized. 1-Benzyl substituted long chain amines, needed for such synthesis, were synthesized starting from Boc-phenylalaninol. The oxidative conversion of a phenyl group to a carboxyl group was used as the key transformation synthetic step. The compounds synthesized were studied for their activity against GIVA PLA(2), and were proven to be weak inhibitors.  相似文献   
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Molecular structure, spectroscopic and photophysical data for the singlet state of 3-benzyl-lumiflavin in different solvents are presented. Theoretical studies concerning singlet-singlet and triplet-triplet excitation energies were carried out using time-dependent density functional theory (TD-DFT) calculations. These predictions are in good agreement with the experimental results, which reflect the solvent interactions. All the observable singlet-singlet transitions have pi-pi* character. The title compound appears to be an efficient sensitizer of the production of singlet oxygen (phi(Delta)= 0.53). The crystal structure of 3-benzyl-lumiflavin is also presented, along with its solid-state photophysical data.  相似文献   
5.
Shifts in native ungulate communities on a former cattle ranch in Tanzania   总被引:3,自引:0,他引:3  
When an area is brought under protection, current animal populations and their habitat preferences need to be assessed to predict population trends and future habitat availability. Using data from walking transects, we estimated the size of native ungulate populations on an abandoned cattle ranch in a coastal savannah in Tanzania, now included in the new Saadani National Park. Data were analysed with distance sampling and conventional strip transect techniques and were compared with results of previous wildlife counts. Few individuals of mainly browsing species were present in former cattle grazing areas exhibiting high bush‐encroachment while a ten times higher biomass of browsers and grazers was found in the cattle‐unmodified savannah. Population sizes of some species increased twofold between 1991 and 2001 within the entire area but neither population size nor species richness increased in the abandoned rangeland during our 3‐year study period from 2001 to 2003. We conclude that the former ranch has potential for future recolonization by wild ungulates. Resettlement will take place gradually with ‘pioneer‐species’ facilitating the entry of more demanding species. Habitat restoration through wildlife can be observed and quantified on Mkwaja Ranch which will be of importance for future management of native ungulates reclaiming abandoned rangeland.  相似文献   
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The paper contains the results of natural film experiments carried out on inland and coastal waters in the Dead Vistula catchment area and mouth during 2000–2002, using the integrated Langmuir trough–Wilhelmy plate system. The static film parameters result from the generalized scaling procedures applied to the surface pressure–area isotherms. They appear to reflect in a quantitative and sensitive way the film composition (Alim, Mw, Eisoth), film solubility and the miscibility of its components (via R, ΔSc and y factors), and surface concentration (πeq, Γeq). The adsorption kinetics parameters: effective diffusion coefficient Deff/D and activation energy barrier Ea/RT are derived from dynamic surface pressure. There is a reason to suggest that certain classes of film-forming components or ‘end-members’ may dominate the static and dynamic surface properties. Variation in the surface rheological parameters of source-specific biosurfactants is postulated to reflect organic matter dynamics in natural waters and were measured for the Dead Vistula river, its tributaries and the adjacent coastal area.  相似文献   
7.
Despite the widespread application of periphytic diatoms to water quality assessment at a regional level, there is no standard European sampling protocol or associated assessment metrics. Furthermore, relatively little is known about the uncertainty in the results of such assessments. One of the objectives of the European project for the Standardisation of River Classifications (STAR) is to improve and standardise diatom assessment methods. An extensive diatom ring test, together with an audit of the project results, provided a better understanding and quantification of the uncertainty in quality assessment of running waters using diatoms. The variation in multimetric analysis shows that the choice of site and substrate for sampling, the inter-operator differences in diatom taxonomy and the counting techniques are the primary sources of uncertainty. To some extent, this variation also reveals the robustness of specific metrics in relation to the sources of uncertainty. Of the three most common substrate types tested (stone, macrophyte and sediment), macrophytes emerge as the most preferred substrate for diatom sampling when performing multimetric water quality assessment.  相似文献   
8.
Species richness, composition and abundance of the bryophyte diaspore bank of Central European temperate mixed forests were compared with the forest-floor bryophyte assemblage. The impact of environmental variables and anthropogenic disturbances, including tree species composition, stand structure, microclimate, light conditions, soil and litter properties, management history, and landscape properties, potentially influencing bryophyte diaspore bank assemblages were explored. Thirty-four, 70–100 years old mixed stands with differing tree species composition were examined in the ?rség National Park, Western Hungary. The diaspore bank was studied by soil collection and cultivation, and data were analysed by multivariate methods. Contrary to the forest-floor bryophyte assemblage, where substrate availability, tree species composition and stand structure were the most influential environmental variables, the composition and abundance of the diaspore bank was mainly affected by site conditions (microclimate, litter and soil properties). Species richness of the bryophyte diaspore bank was lower than that of the forest-floor bryophyte assemblage. Short-lived mosses (colonists, short-lived shuttles) were dominant in the diaspore bank, as opposed to the forest-floor bryophyte community, where perennial mosses dominated. In the studied forests, the importance of the bryophyte diaspore bank was relatively low in the regeneration and maintenance of the forest-floor bryophyte vegetation.  相似文献   
9.
MicroRNAs (miRNA) precursor (pre-miRNA) molecules can be processed to release a miRNA/miRNA* duplex. In the canonical model of miRNA biogenesis, one strand of the duplex is thought to be the biologically active miRNA, whereas the other strand is thought to be inactive and degraded as a carrier or passenger strand called miRNA* (miRNA star). However, recent studies have revealed that miRNA* strands frequently play roles in the regulatory networks of miRNA target molecules. Our recent study indicated that miR-17 transgenic mice could abundantly express both the mature miR-17-5p and the passenger strand miR-17-3p. Here, we showed that miR-17 enhanced prostate tumor growth and invasion by increasing tumor cell proliferation, colony formation, cell survival and invasion. miRNA target analysis showed that both miR-17-5p and miR-17-3p repressed TIMP metallopeptidase inhibitor 3 (TIMP3) expression. Silencing with small interfering RNA against TIMP3 promoted cell survival and invasion. Ectopic expression of TIMP3 decreased cell invasion and cell survival. Our results demonstrated that mature miRNA can function coordinately with its passenger strand, enhancing the repressive ability of a miRNA by binding the same target. Within an intricate regulatory network, this may be among the mechanisms by which miRNA can augment their regulatory capacity.  相似文献   
10.
Beginning with the premise that sovereignty may be most constructively contemplated not as a definable object or objective but instead as a process, this article examines counter-mapping as a way for contemporary indigenous citizens to “do” sovereignty. It surveys three Anishinaabe/Ojibwe communities’ recent use of geographical techniques to communicate their own territorial claims and counter the competing claims of others. In a 21st century context characterized by urgent extractive-industrial threats to indigenous landbases and lifeways, the cases presented here demonstrate that counter-mapping can serve as a powerful positive tool. Yet because the prevailing methods available to safeguard land-based self-determination also have the potential to undermine it, I conclude by considering some of the pitfalls that complicate counter-mapping’s ability to promote the sovereignty process. I suggest that indigenous people who choose to enact their sovereignty in this manner are indeed empowered, but only within an existing—and inequitable—socio-political system.  相似文献   
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