Elisabeth Gratia

Discrimination between the ionic and osmotic components of salt stress in relation to free polyamine level in rice (Oryza sativa)

In order to precise the relative importance of ionic and osmotic components of salt stress on modification of free polyamine level, seedling of two rice cultivars (I Kong Pao (IKP): salt-sensitive and Pokkali: salt-resistant) were exposed to isoosmotic concentrations of NaCl, KCl (50 and 100 mM) or polyethylene glycol (PEG 6000, 16 and 26%) for a maximal period of 12 h in daylight conditions, Both ion and polyamine concentrations were already modified after 3 h of exposure to ionic stresses. At the shoot level. this response occurred independently of any change in the plant water status. Conversely, exposure to 26% PEG during 12 h induced a strong decrease in shoot osmotic potential and water content but had only a limited impact on endogenous free polyamine level. It was thus suggested that the ionic component by itself might trigger short-term polyamine accumulation. This effect might be attributed to monovalent ions, although K+ and Na+ accumulation had different effects on polyamine content. Putrescine may assume differential role in non-photosynthetic organs versus photosynthetic ones since it accumulated to high amounts in the roots of the salt-resistant cultivar Pokkali comparatively to salt-sensitive cultivar IKP. while an opposite trend was recorded in the shoots. Tyramine was also present at hi.-her concentrations in the roots of Pokkali;, its level clearly increased in response to ionic stresses while cadaverine level increased in water stress conditions only. No clear relationship was observed between the mean level of salinity resistance and the endogenous concentrations of spermidine or spermine

A simple design tool for the thermal study of an office building

The objective of the OPTI program (the office building module) is to help architects, engineers and design departments to take into account the impact of design choices on energy consumption designing a project. In order to do so, the program must: be highly user-friendly (language based on drawings); need a minimum of data; be very fast. The computation of energy needs and overheating estimation require dynamic thermal programs. These are often slow and need a large amount of data. The use of many parametric studies realized with a dynamic thermal program along with the application of a method used in experimental research (method of experimental design) allowed us to create software providing the user instantaneously with results from a dynamic thermal program without subjecting architects to the disadvantages of this type of program. Indeed, the program provides annual thermal needs and thermal comfort (winter and summer) in relation with orientation, building footprint, window area and type, internal gains, presence of external or internal shading devices, ventilation strategy applied and thermal mass. This design tool is based on Belgian climatic weather data but the same step could be transposed to other climatic data

A simple design tool for the thermal study of dwellings

The objective of the OPTI program (the dwellings module) is to help architects to take into account the impact of design choices on energy consumption designing a dwelling project. In order to do so, the program must: be highly user-friendly (language based on drawings); need a minimum of data and be very fast. The computation of energy needs and overheating estimation require dynamic thermal programs. These are often slow and need a large amount of data. The use of many parametric studies realized with a dynamic thermal program allowed us to create software providing the user instantaneously with results from a dynamic thermal program without subjecting architects to the disadvantages of this type of program. Indeed, the program provides annual thermal needs and thermal comfort (winter and summer) in relation with orientation, building footprint, window area and type, insulation level, presence of external or internal shading devices, ventilation strategy applied and thermal mass. This design tool is based on Belgian climatic weather data but the same step could be transposed to other climatic data