Remarks on the effects of nitrogen deposition to forest ecosystems

The effects of increased deposition of nitrogen compounds on forest sites are discussed based on literature data and own results from both earlier fertilization experiments and the ARINUS study area in the Black Forest. The influence on mycorrhiza is stated suppressive as well as stimulating so that no general conclusion can be drawn. The nitrogen nutrition status of coniferous forests is still sub-optimal over wide areas with a yearly deposition of 10–20 kg N ha^-1. Under considerable higher input rates the insufficient supply of other nutrients and imbalances in the nutritional status of trees are possible. When discussing nitrogen saturation of ecosystems, the nitrogen storage capacity of soils has to be considered as a decisive factor which varies from site to site. Any actual input/output balance is strongly influenced by the internal turnover processes resulting from former land use.     

Peripheral skin temperature effects on muscle oxygen levels

In both hot and cold environments, tissue oxygen saturation levels may affect muscle performance. Using near-infrared spectroscopy, muscle oxygen saturation (StO2) and total hemoglobin levels were measured during exercise. Lowering skin temperature caused a greater StO2 and total hemoglobin decrease by 16% and 15.9%, respectively, compared to controls. Increasing skin temperature resulted in a smaller decrease in both StO2 and total hemoglobin by 12.2% and 8.2%, respectively, compared to controls. These data indicate that warming the skin will cause less of decrease in StO2 and total hemoglobin, while cooling the skin has the opposite effect.     

槲皮素的抗活性氧作用

本文在体外测定了槲皮素对白细胞吞噬发光体系、黄嘌呤－黄嘌呤氧化酶发光体系及碱性连二亚硫酸钠发光体系的影响,结果表明槲皮素对上述三个发光体系均有不同程度的抑制作用,其ＩＣ５０分别是１７．８,２．２４和２２．３μｍｏｌ／Ｌ。提示槲皮素既可抑制白细胞吞噬产生的活性氧,又可减少黄嘌呤－黄嘌呤氧化酶系的Ｏ－２形成,或兼有直接清除活性氧的作用