42 research outputs found

    Leaf physiological and morphological constraints of water-use efficiency in C3_3 plants

    Get PDF
    The increasing evaporative demand due to climate change will significantly affect the balance of carbon assimilation and water losses of plants worldwide. The development of crop varieties with improved water-use efficiency (WUE) will be critical for adapting agricultural strategies under predicted future climates. This review aims to summarize the most important leaf morpho-physiological constraints of WUE in C3 plants and identify gaps in knowledge. From the carbon gain side of the WUE, the discussed parameters are mesophyll conductance, carboxylation efficiency and respiratory losses. The traits and parameters affecting the waterside of WUE balance discussed in this review are stomatal size and density, stomatal control and residual water losses (cuticular and bark conductance), nocturnal conductance and leaf hydraulic conductance. In addition, we discussed the impact of leaf anatomy and crown architecture on both the carbon gain and water loss components of WUE. There are multiple possible targets for future development in understanding sources of WUE variability in plants. We identified residual water losses and respiratory carbon losses as the greatest knowledge gaps of whole-plant WUE assessments. Moreover, the impact of trichomes, leaf hydraulic conductance and canopy structure on plants’ WUE is still not well understood. The development of a multi-trait approach is urgently needed for a better understanding of WUE dynamics and optimization

    Operation of the photovoltaic system in Prague and data evaluation

    Get PDF
    Received: January 6th, 2021 ; Accepted: April 7th 2021 ; Published: April 12th 2021 ; Correspondence: [email protected] on-grid photovoltaic system was installed at the Faculty of Engineering in 2015. The monitoring system developed in our laboratory monitors data and can also detect failure and type of failure. The evaluation of the data shows that the amount of electricity produced slightly exceeds the expected values predicted by the internationally used internet application PVGIS. The effect of the aging of PV panels has so far had a minimal effect on the electricity produced. Immediate output power is affected by multiple parameters. Higher temperatures reduce the efficiency of energy conversion, so in summer the instantaneous power may be lower even at higher radiation intensity and smaller angle of incidence

    The Role of Provenance for the Projected Growth of Juvenile European Beech under Climate Change

    Get PDF
    European beech is one of the most common tree species in Europe and is generally suggested to play even more of a prominent role in forestry in the future. It seems to have the potential to partially replace Norway spruce, as it is less sensitive to expected warmer and drier conditions. It is, however, not well known in which regions these new plantings would be particularly favourable and if specific provenances may be better adapted to the new conditions than others. Therefore, we estimated the potential early height growth under climate conditions in 2040–2060 for 20 beech provenances across a region covering the Czech Republic and Slovakia. This Central European region is expected to experience considerably drier and warmer conditions in the future. For this exercise, we implemented a new neural network model developed from height growth information obtained from the open-access BeechCOSTe52 database. The simulations are driven by past and future climate data obtained from the WorldClim database of historical climate data and future climate projections. Simulations revealed that provenances originating from drier regions performed on average significantly better than those from regions with good water supply. Moreover, provenances originating from drier regions had a particularly large advantage in the relatively arid regions of Central Czechia and Southern Slovakia. We can also confirm that all provenances showed a high phenotypic plasticity of height growth across the whole investigated region

    Protracted shearing at mid‐crustal conditions during large‐scale thrusting in the Scandinavian Caledonides

    Get PDF
    During continental collision, large tracts of crust are mobilised along major shear zones. The metamorphic conditions at which these zones operate, the duration of thrusting, and the deformation processes that facilitated hundreds of km of tectonic transport are still unclear. In the Scandinavian Caledonides, the Lower Seve Nappe displays a main mylonitic foliation with thickness of ~1 km. This foliation is overprinted by a brittle‐to‐ductile deformation pattern localized in C and C’‐type shear bands proximal to the tectonic contact with the underlying SĂ€rv Nappe. Thermobarometry of amphibolites and micaschists suggest a first high‐pressure stage at 400‐500°C and 1‐1.3 GPa recorded in mineral relics. The main mylonitic foliation developed under epidote amphibolite facies conditions along the retrograde path from 600°C and 1 GPa to 500°C and 0.5 GPa. Age dating of synkinematic titanite grains in the amphibolites indicates that this mylonitic fabric formed at around 417 ± 9 Ma, but older ages spanning 460‐430 Ma could represent earlier stages of mylonitization. The shear bands developed at lower metamorphic conditions of 300‐400°C and ~0.3 GPa. In the micaschists, the recrystallized grain size of quartz decreases towards the shear bands. Monomineralic quartz layers are eventually dismembered to form polyphase aggregates deforming by dominant grain size sensitive creep accompanied by slip in muscovite and chlorite. Plagioclase zoning truncations suggest that the shear bands originated by fracturing followed by ductile deformation. The results suggest protracted and long‐lasting shearing under amphibolite to greenschist facies conditions during the juxtaposition, stacking and exhumation of the Lower Seve Nappe

    Research of the influence of mechanical vibration over human

    No full text
    Car seat producers and research laboratories are focused on the influence of mechanical vibrations on humans. It stands to reason that value of transmissibility of mechanical vibrations onto human body depends on quality of vibro-isolation properties of car seat. Negative effects of mechanical vibrations to a person may be characterized by means of events and parameters, changes in health state, rising temperature and blood pressure, accelerated breath, short-time and long-time tediousness, etc. Mechanical vibrations evoke mechanical oscillations of human body in relation to its intensity. Determination of absorbed–dissipated energy in human body is the object of research and summary of this articl

    Research of the influence of mechanical vibration over human

    No full text
    Car seat producers and research laboratories are focused on the influence of mechanical vibrations on humans. It stands to reason that value of transmissibility of mechanical vibrations onto human body depends on quality of vibro-isolation properties of car seat. Negative effects of mechanical vibrations to a person may be characterized by means of events and parameters, changes in health state, rising temperature and blood pressure, accelerated breath, short-time and long-time tediousness, etc. Mechanical vibrations evoke mechanical oscillations of human body in relation to its intensity. Determination of absorbed–dissipated energy in human body is the object of research and summary of this articl

    Interaction of molten salts in the systems SiO2-Al2O3

    No full text
    The aim of this study was to realize and evaluate laboratory corrosion tests for a solution of problems such as wear of refractory materials at processing of aluminum, for example. The static crucible corrosion tests were carried out in laboratory resistive furnace at 850 °C during 2 h air atmosphere. Two standards of alumina-silica shaped refractory bricks were used as a corroding material. Pure sodium chloride and potassium chloride were applied as a corrosive media. The results of tests were evaluated by macroscopic, microscopic, chemical and semiquantitative EDX analysis. Sodium chloride shows more significant penetration and chemical interaction in penetrated area. EDX analysis confirms creation of the reaction layer between chlorides and elements of refractory lining. The products of reactions penetrate more deeply into A lining. K ions penetrate into the grains of the lining more intense than Na ions

    Comparison of Cupola Furnace and Blast Furnace Slags with Respect to Possibilities of Their Utilization

    No full text
    Blast furnace and cupola furnace are furnace aggregates used for pig iron and cast iron production. Both furnace aggregates work on very similar principles: they use coke as the fuel, charge goes from the top to down, the gases flow against it, etc. Their construction is very similar (cupola furnace is usually much smaller) and the structures of pig iron and cast iron are very similar too. Small differences between cast iron and pig iron are only in carbon and silicon content. The slags from blast furnace and cupola furnace are very similar in chemical composition, but blast furnace slag has a very widespread use in civil engineering, primarily in road construction, concrete and cement production, and in other industries, but the cupola furnace slag utilization is minimal. The contribution analyzes identical and different properties of both kinds of slags, and attempts to explain the differences in their uses. They are compared by the contribution of the blast furnace slag cooled in water and on air, and cupola furnace slag cooled on air and granulated in water. Their chemical composition, basicity, hydraulicity, melting temperature and surface were compared to explain the differences in their utilization
    corecore