CODEX-CT-1 experiment: Quenching of fuel bundle after long term oxidation in hydrogen rich steam KFKI-2008-01/G

The cleaning tank incident at the unit 2 of Paks NPP in 2003 resulted in severe fuel damage of 30 assemblies. The fuel rods heated up due to insufficient cooling and the zirconium components suffered heavy oxidation. Opening of the tank and quenching of the assemblies by cold water led to fragmentation of brittle zirconium components. Due to the poor instrumentation there were many open questions concerning the course of the incident and the behaviour of fuel assemblies. In order to improve the understanding of the phenomena that took place during the Paks-2 incident integral tests have been carried out in the CODEX (Core Degradation Experiment) facility. The tests simulated the whole scenario of the incident using electrically heated fuel rods. The final state of the fuel rods showed many similarities with the conditions observed after the incident at the NPP and for this reason it is very probable that the thermal conditions and chemical reactions were also similar in the tests and in the incident. The post-test examination of CODEX-CT-1 bundle indicated that the high degree of embrittlement was a common result of oxidation and hydrogen uptake by the Zr components

CODEX-CT-2 experiment: Long term treatment in high temperature hydrogen and water quenching of a fuel bundle KFKI-2008-02/G

The simulation of the Paks-2 incident was carried out in the frame of an experimental programme in the CODEX facility with electrically heated fuel rod bundles. The main boundary conditions for the CODEX-CT-2 were similar to the previous CODEX-CT-1 test. The most significant difference between the two tests was the operation of the air let down valve that was open in the first test and closed in the second one. In the second test the hydrogen produced in the Zr-steam reaction could not escape from the test section and it prevented the access of steam to the Zr surfaces and caused much less oxidation than was observed in the first tests. The final quench by water led to temperature excursion in the bundle and in the shroud. The final state of the bundle was very brittle, the fuel rods and the shroud were cracked and fragmented

An attempt to partition stomatal and non-stomatal ozone deposition parts on a short grassland

To evaluate the damaging effect of tropospheric ozone on vegetation, it is important to evaluate the stomatal uptake of ozone. Although the stomatal flux is a dominant pathway of ozone deposition onto vegetated surfaces, non-stomatal uptake mechanisms such as soil and cuticular deposition also play a vital role, especially when the leaf area index LAI<4. In this study, we partitioned the canopy conductance into stomatal and non-stomatal components. To calculate the stomatal conductance of water vapour for sparse vegetation, we firstly partitioned the latent heat flux into effects of transpiration and evaporation using the Shuttleworth–Wallace (SW) model. We then derived the stomatal conductance of ozone using the Penman–Monteith (PM) theory based on the similarity to water vapour conductance. The non-stomatal conductance was calculated by subtracting the stomatal conductance from the canopy conductance derived from directly-measured fluxes. Our results show that for short vegetation (LAI=0.25) dry deposition of ozone was dominated by the non-stomatal flux, which exceeded the stomatal flux even during the daytime. At night the stomatal uptake of ozone was found to be negligibly small. In the case of vegetation with LAI≈1, the daytime stomatal and non-stomatal fluxes were of the same order of magnitude. These results emphasize that non-stomatal processes must be considered even in the case of well-developed vegetation where cuticular uptake is comparable in magnitude with stomatal uptake, and especially in the case of vegetated surfaces with LAI<4 where soil uptake also has a role in ozone deposition

Change of composition and diversity of species and grassland management between different grazing intensity in Pannonian dry and wet grasslands

Investigations were carried out in wet and dry pasture. Coenological recordings were taken in three zones. The first zone (“A”) located 0-50 m near the stable, second zone (“B”) located 50-150 m from the stable, while the third zone (“C”) located farther than 150 m. We have carried out analyses of ecological and environmental factors and life form types. Based on our results for both dry and wet grasslands, quadrates of “A” zone were well isolated from the rest of the zones. Overgrazing, which involves considerable trampling, vanishes differences among vegetations, thereby promotes weed and disturbance tolerant rich vegetation. The lowest species number and diversity could be found here. Due to the nitrogen enrichment due to the constant presence of livestock, drier and less heat demanding habitat developed in the “A” zones, according to the environmental indicators. Because of the change in management, conservation and diversity values of “C” zone increased, however, according to nature protection values it underperformed compared to “B” zone. According to the sample area, wet grasslands from the sandy areas of Kiskunság, preserve nature protection values and grass composition better moving away from stables, due to less grazing pressure. Drier backgrounds tolerate stronger grazing pressure

THE IMPACT OF GEL ELECTROPHORESIS UPON OUR UNDERSTANDING OF THE ESTERASES *

The impact of gel electrophoresis upon our understanding of the esterases has been formidable in that it has provided us with new insights and understanding concerning the number and biochemical characteristics of the many esterase-active proteins found in biological material. The relationships between the esterases within a species and among species still remains largely to be determined. With regard to the function of esterases it is to be expected that there will be several. One promising possibility is suggested by the work of Allen and Hunter, which illustrated a dependent relationship between male sex hormone and the esterases in the mouse epididymis. Supporting this work is the observation by Shaw and Koen (1963) demonstrating the presence of an esterase in the mouse kidney, which also was dependent on male sex hormone. The change observed in the serum esterase of the pregnant rabbit reported here and in women by Friedman and Lapman (1961) may also relate to hormone changes associated with pregnancy, although this relationship remains to be demonstrated. A second area where the esterases are likely to be functioning is in relation to protein synthetic activity of the endoplasmic reticulum. The only evidence supporting this suggestion is the abundant presence of esterases found in this location. The seven experiments described and discussed here along with those included in the references may serve as illustrations of the kind of work that can be accomplished by the use of these methods.*Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75632/1/j.1749-6632.1964.tb14224.x.pd

Extracellular deposition of matrilin-2 controls the timing of the myogenic program during muscle regeneration.

Here, we identify a role for the matrilin-2 (Matn2) extracellular matrix protein in controlling the early stages of myogenic differentiation. We observed Matn2 deposition around proliferating, differentiating and fusing myoblasts in culture and during muscle regeneration in vivo. Silencing of Matn2 delayed the expression of the Cdk inhibitor p21 and of the myogenic genes Nfix, MyoD and Myog, explaining the retarded cell cycle exit and myoblast differentiation. Rescue of Matn2 expression restored differentiation and the expression of p21 and of the myogenic genes. TGF-β1 inhibited myogenic differentiation at least in part by repressing Matn2 expression, which inhibited the onset of a positive-feedback loop whereby Matn2 and Nfix activate the expression of one another and activate myoblast differentiation. In vivo, myoblast cell cycle arrest and muscle regeneration was delayed in Matn2(-/-) relative to wild-type mice. The expression levels of Trf3 and myogenic genes were robustly reduced in Matn2(-/-) fetal limbs and in differentiating primary myoblast cultures, establishing Matn2 as a key modulator of the regulatory cascade that initiates terminal myogenic differentiation. Our data thus identify Matn2 as a crucial component of a genetic switch that modulates the onset of tissue repair