207 research outputs found
SEPARATION OF OPTICAL ISOMERS VIA DIASTEREOISOMERIC SALT FORMATION
The optical resolution processes were systematically investigated. The optimum of the
parameters of the diastereoisomeric salt formation can be determined by using a thermodynamic
equilibrium model. Based upon the conformational analysis of the structure for diastereo
isomeric salts, a new method has been elaborated for designing optical resolutions
Non-equivalent roles for the first and second zinc fingers of protein kinase Cdelta: effect of their mutation on phorbol ester-induced translocation in NIH 3T3 cells
The catalytic domain of protein kinase C chimeras modulates the affinity and targeting of phorbol ester-induced translocation
Both the catalytic and regulatory domains of protein kinase C chimeras modulate the proliferative properties of NIH 3T3 cells
Climate and land-use as the main drivers of recent environmental change in a mid-altitude mountain lake, Romanian Carpathians
Recent decades have been marked by unprecendented environmental changes which threaten the integrity of freshwater systems and their ecological value. Although most of these changes can be attributed to human activities, disentagling natural and anthropogenic drivers remains a challenge. In this study, surface sediments from Lake Ighiel, a mid-altitude site in the Carpathian Mts (Romania) were investigated following high-resolution sedimentological, geochemical, environmental magnetic and diatom analyses supported by historical cartographic and documentary evidence. Our results suggest that between 1920 and 1960 the study area experienced no significant anthropogenic impact. An excellent correspondence is observed between lake proxy responses (e.g., growth of submerged macrophytes, high detrital input, shifts in diatom assemblages) and parameters tracking natural hydroclimate variability (e.g., temperature, NAO). This highlights a dominant natural hydroclimatic control on the lacustrine system. From 1960 however, the depositional regime shifted markedly from laminated to homogenous clays; since then geochemical and magnetic data document a trend of significant (and on-going) subsurface erosion across the catchment. This is paralleled by a shift in lake ecosystem conditions denoting a strong response to an intensified anthropogenic impact, mainly through forestry. An increase in detrital input and marked changes in the diatom community are observed over the last three decades, alongside accelerated sedimentation rates following enhanced grazing and deforestation in the catchment. Recent shifts in diatom assemblages may also reflect forcing from atmospheric nitrogen (N) deposition, a key recent drive of diatom community turnover in mountain lakes. In general, enhanced human pressure alongside intermittent hydroclimate forcing drastically altered the landscape around Lake Ighiel and thus, the sedimentation regime and the ecosystem’s health. However, paleoenvironmental signals tracking natural hydroclimate variability are also clearly discernible in the proxy data. Our work illustrates the complex link between the drivers of catchment-scale impacts on one hand, and lake proxy responses on the other, highlighting the importance of an integrated historical and palaeolimnological approach to better assess lake system changes
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