Metallic surface temperature at the very beginning of the laser-induced breakdown obtained from black-body radiation.

We present experimental results of cooper surface temperature measured nanosecond by nanosecond at the very beginning of the laser-induced breakdown experiment. The experiment is conducted by Nd:YAG laser for three irradiances: 1.4×10^{9}, 3.2×10^{11}, and 3.7×10^{12} W/cm^{2}. The temperatures of the metal surface, before plasma is created, are in the interval 7 400-11 200 K. These values are close to most estimates for the critical temperature of copper. The moment when plasma was created is recognized applying a bifurcated optical cable. After creation, temperature of the plasma increases attaining values over 50 000 K. All temperatures are derived relying on continuous spectra emitted from the bright spot illuminated by the laser.

Cell wall response to UV radiation in needles of Picea omorika.

The UV-B represents the minor fraction of the solar spectrum, while UV-C is not contained in natural solar radiation, but both radiation types can cause damaging effects in plants. Cell walls (CWs) are one of the targets for external stressors. Juvenile P. omorika trees were treated either with 21 day-high doses UV-B or with 7 day- UV-C in open-top chambers. Using spectroscopic and biochemical techniques, it was shown that the response to UV radiation includes numerous modifications in needle CW structure: relative content of xylan, xyloglucan, lignin and cellulose decreased; cellulose crystallinity changed; yield of lignin monomers with stronger connection of CC in side chain with the ring increased; re-distribution of inter- and intra-polymer H-bonds occurred. The recovery was mediated by an increase in the activities and changes in isoform profiles of CW bound covalent peroxidases (POD) and polyphenol oxidases (PO) (UV-B), and ionic POD and covalent PO (UV-C). A connection between activities of specific POD/PO isoforms and phenolic species (m- and p-coumaric acid, pinoresinol and cinnamic acid derivatives) was demonstrated, and supported by changes in the sRNA profile. In vivo fluorometry showed phenolics accumulation in needle epidermal CWs. These results imply transversal connections between polymers and changed mechanical properties of needle CW as a response to UV. The CW alterations enabled maintenance of physiological functions, as indicated by the preserved chlorophyll content and/or organization. The current study provides evidence that in conifers, needle CW response to both UV-B and UV-C includes biochemical modifications and structural remodeling.