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Number of results: 29
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Abstract

This article analyses the conditions affecting the incoming global solar radiation in Hornsund (Spitsbergen) in spring of 2015. Incoming solar radiation turned out to be average for the season under analysis, as compared with longer-term data. The clearness index (KT) was 0.46, and was mainly determined by the extent of cloudiness. As a result of differences in the length of day, sunshine duration in May was greater than in April. Incoming solar radiation to the earth's surface is also affected by the atmospheric optical properties. The average value of aerosol optical depth (AOD) at 500 nm in Hornsund in spring of 2015 was 0.087. In the analysed period, increased values of AOD at 500 nm (up to 0.143) were observed, although these are not record values. Over April and May, the greatest part of optical depth was comprised of anthropogenic aerosols (41%), followed by marine aerosols (26%), desert dust (21%) and biomass-burning aerosols (12%). This indicates the significant role of the anthropogenic factor in the climatic conditions of Spitsbergen.
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Abstract

The aim of the study was to evaluate the effect of pre-sowing seed stimulation of Thuringian Mallow (Lavatera thuringiaca L.) with He-Ne laser light of different exposure times on the crop yield as well as on energetic parameters such as calorific value and combustion heat. Seeds were subjected to laser light with an exposition time of 0, 1, 5, 10, 15 and 30 minutes. Measurements were carried out independently on mature plants from the first and second vegetation year. The results varied between the samples, which indicated possible impact of laser radiation on the resultant weight and calorific value of various experimental combinations. For plants from the second vegetation year the statistical differences in calorific value, combustion heat and crop mass were found between samples characterized by different exposition times: between sample irradiated for 30 min (L30) and 1 min (L1) as well as between sample L30 and sample irradiated for 5 minutes (L5). For plants after the first vegetation year the statistically significant differences in calorific value and combustion heat were found for sample with exposition time of 15 minutes (L15) and control sample, for sample L15 and sample L5 as well as between samples L15 and L30. For all the samples from the second vegetation year the increase in combustion heat and calorific values were detected as compared to control. Thus, after the application of certain parameters of laser radiation to the processing of seeds, the plant can be more useful for energetic purposes through more efficient crop.
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Abstract

The paper presents a study of the performance of some selected UV detectors. Unlike many similar works, the obtained data refer to commercial photodiodes (not only to detector materials). The main task of the research was to determine the influence of the operating temperature and annealing on the detector spectral responsiveness. A comparison of the results obtained for the photodiodes made of GaN and SiC was also performed. Although both kinds of detectors can work at high temperatures for a long time, some modification of their properties was observed. However, for GaN and SiC photodiodes, this modification has a substantially different nature. It is very important for some applications, e.g. fire alarms and a military equipment.
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Abstract

This study examined the effects of UV-B radiation and allelochemical stress induced by ferulic acid (FA) on the activity of phenylalanine ammonia lyase (PAL; EC 4.3.1.5) at metabolic and molecular levels in two cucumber genotypes differing in tolerance to cold and disease, in order to determine any interaction between stress effects and genotype response. Stresses were applied simultaneously, sequentially, and singly. In both genotypes, several days of UV radiation retarded growth up to 36%. The effect of FA was not significant. The response to a particular stress, including the effect on PAL activation, was enhanced by simultaneous application of the two stresses. PAL transcription was not correlated with the increase of PAL activity. Exposure to UV-B, FA, and combined UV-B and FA was detrimental to both genotypes but to different extents. The response was not correlated with the genotype of cold and disease sensitivity. PAL activity and its transcription seem to be involved in UV and allelochemical stress, but not related to the plants' tolerance of these stresses.
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