The effect of temperature on bacterial self-healing processes in building materials

This paper is focused on the bacterial induced calcitation for the crack healing. The bacteria applied for this purpose are from group which is adapted for growth in the high pH environment as a concrete in hydration phase and their metabolic activity leads to create of calcite. In this study, three different bacteria strains (Sporosarcina pasteurii, Bacillus cohnii, Bacillus pseudofirmus) were applied and the influence of various temperatures on their microbial properties was investigated. Our previous experiment indicated that one of the applied bacterial strain in spores form (Bacillus pseudofirmus) are able to survive the temperatures in the range from −20 °C to 140 °C. The xperiment described in this paper extends the previous study and determines the effect of different temperatures on the change in growth activity. In this experiment, bacterial activity was determined based on the change of absorbance in 640 nm by spectrophotometric measurements. The experiment was performed at optimal temperature (30 °C) and lower temperature (10 °C) and it used suitable broth for calcitation. The results showed that the beginning of metabolic activity was shifted by 40 to 50 hours. Only Bacillus cohnii showed different results because its metabolic activity was nearly zero at 10 °C

Photosynthetic characteristics of lichens of genus Umbilicaria from SW Greenland (Nuuk area) in reponse to thallus dehydration.

Thalli of foliose epilithic lichens Umbilicaria arctica and U.hyperborea were collected on the rocks at several locations in the neighbourhood of Nuuk, and transported to the Czech Republic where kept in dry state in dark at 5 oC before experiments. After 48 h rehydration, simultaneous measurements of (1)effective quantum yield (YieldPSII) of photosystem II, (2)photochemical reflectance index (PRI), (3)normalized difference vegetation index (NDVI), (4)chlorophyll fluorescence fast kinetics (OJIP) were made in response to gradual thallus dehydration expressed as water potential (WP). Dehydration-response curves of YieldPSII showed S-curve relationship. In both species, the first signs of inhibition of photosynthetic processes appeared at WP of about -10 MPa. Further dehydration led to a decrease in YieldPSII and, finally, full inhibition of PSII photochemical photosynthetic processes. Critical point for PSII processes was found at WP of about -25 MPa, similarly to other epilithic lichens investigated by this methodVyl studován vztah mezi fůznými fotosyntetickými charakteristikami lišejníků Umbilicaria arctica a Umbilicaria Hyperboera ve vztahu k vyschnutí stélky.Thalli of foliose epilithic lichens Umbilicaria arctica and U.hyperborea were collected on the rocks at several locations in the neighbourhood of Nuuk, and transported to the Czech Republic where kept in dry state in dark at 5 oC before experiments. After 48 h rehydration, simultaneous measurements of (1)effective quantum yield (YieldPSII) of photosystem II, (2)photochemical reflectance index (PRI), (3)normalized difference vegetation index (NDVI), (4)chlorophyll fluorescence fast kinetics (OJIP) were made in response to gradual thallus dehydration expressed as water potential (WP). Dehydration-response curves of YieldPSII showed S-curve relationship. In both species, the first signs of inhibition of photosynthetic processes appeared at WP of about -10 MPa. Further dehydration led to a decrease in YieldPSII and, finally, full inhibition of PSII photochemical photosynthetic processes. Critical point for PSII processes was found at WP of about -25 MPa, similarly to other epilihic lichens investigated by this metho

Facilities of J. G. Mendel Antarctic station: Technical and technological solutions with a special respect to energy sources

In this paper, we focus on technical facilities and technologies used at the Johann Gregor Mendel station (James Ross Island, Antarctica) with a special respect to energy sources used for running the station. Construction of the station is evaluated from energy demand and energy loss points of view. Detailed description of main energy sources, i.e. wind turbines, solar thermal panels, and diesel generators is given. Water management and combustible solid waste management are described as well. Brief overview of future plans related to energy sources at the Johann Gregor Mendel station including an increase in the exploitation of solar energy from photovoltaic panels is given.V článku jsou popsána technická zařízení antarktické stanice J.G.Mendela s ohledem na využití zdrojů energie: větrné elektrárny, solární panely, fotovoltaické články, diesel agregáty. Pozornost je rovněž věnovány konstrukci stanice z hledika vytápění a optimalizace využití energie.In this paper, we focus on technical facilities and technologies used at the Johann Gregor Mendel station (James Ross Island, Antarctica) with a special respect to energy sources used for running the station. Construction of the station is evaluated from energy demand and energy loss points of view. Detailed description of main energy sources, i.e. wind turbines, solar thermal panels, and diesel generators is given. Water management and combustible solid waste management are described as well. Brief overview of future plans related to energy sources at the Johann Gregor Mendel station including an increase in the exploitation of solar energy from photovoltaic panels is given

Climate and Climate Change at Hornsund, Svalbard

Andrzej A. Marsz and Anna Styszyńska (eds.)Gdynia Maritime University, Gdynia, 2013. ISBN: 978-83-7421-191-8, 402 pages

Antarktida (Antarctica)

Forthcoming monography on Antarctica in Czech. Alert. Book Preview

Changing Cold Environments. A Canadian perspective

Hugh French, Olav Slaymaker (eds.)Wiley-Blackwell, Chichester, 2011. ISBN 978-0-470-69969-0, 321 pages

RELAP5/MOD3.3 Analyses of Core Heatup Prevention Strategy during Extended Station Blackout in PWR

The accident at the Fukushima Dai-ichi nuclear power plant demonstrated the vulnerability of the plants on the loss of electrical power for several days, so called extended station blackout (SBO). A set of measures have been proposed and implemented in response of the accident at the Fukushima Dai-ichi nuclear power plant. The purpose of the study was to investigate the application of the deterministic safety analysis for core heatup prevention strategy of the extended SBO in pressurized water reactor, lasting 72 h. The prevention strategy selected was water injection into steam generators using turbine driven auxiliary feedwater pump (TD-AFW) or portable water injection pump. Method for assessment of the necessary pump injection flowrate is developed and presented. The necessary injection flowrate to the steam generators is determined from the calculated cumulative water mass injected by the turbine driven auxiliary feedwater pump in the analysed scenarios, when desired normal level is maintained automatically. The developed method allows assessment of the necessary injection flowrates of pump, TD-AFW or portable, for different plant configurations and number of flowrate changes. The RELAP5/MOD3.3 Patch04 computer code and input model of a two-loop pressurized water reactor is used for analyses, assuming different injection start times, flowrates and reactor coolant system losses. Three different reactor coolant system (RCS) coolant loss pathways, with corresponding leakage rate, can be expected in the pressurized water reactor (PWR) during the extended SBO: normal system leakage, reactor coolant pump seal leakage, and RCS coolant loss through letdown relief valve unless automatically isolated or until isolation is procedurally directed. Depressurization of RCS was also considered. In total, six types of RCS coolant loss scenarios were considered. Two cases were defined regarding the operation of the emergency diesel generators. Different delays of the pump injection start following the station blackout were assumed and analysed. For each scenario, two kinds of SBO calculations for two-loop PWR were performed, base and verification. Base calculations were needed to determine necessary minimum flowrate for steam generators feeding in such a way that they are not overfilled or emptied. Namely, it was assumed that instrumentation is not available during extended SBO. The verification calculations have been then performed to verify if the determined minimum flowrates are sufficient to prevent the core heatup. The calculated results show effectiveness of the proposed extended SBO prevention strategy provided that the water injection is available in the first two hours after SBO occurring at full power. If diesel generator is running after loss of offsite power for some time, e.g. one hour, the available time for steam generator water injection is significantly longer. The obtained results demonstrate the need for assessment of the pump injection flowrates before the utilization of the pump for mitigation of the event. The applicability of the developed method for assessment of the required pump injection flowrate has been validated on PWR

CEMENT PASTE CONTAINING MICRONIZED RECYCLED CONCRETE - INFLUENCE OF HARDENING ACCELERATORS ON THE MODULUS OF ELASTICITY

The article deals with the selection of a suitable hardening accelerator for cement composite material for mass production of masonry blocks. The blocks contain cement and finely ground recycled concrete in ratio 1:1. Three different hardening accelerators in different quantity were tested for possibility of fast removing formwork. The dynamic modulus of elasticity was measured by non-destructive resonance method to determine the initial strengths. The modulus of elasticity was measured 7 and 12 hours after sample production to determine the increase in initial strength. Subsequently, the modulus of elasticity was measured at 1, 7, 14, 21 and 28 days after production of the test specimens. The resulting moduli of elasticity were compared with reference samples