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Dissolved and gaseous nitrogen losses in forests controlled by soil nutrient stoichiometry
Oulehle, Filip ; Chuman, T. ; Hruška, Jakub ; Krám, Pavel ; Navrátil, Tomáš ; Tesař, Miroslav ; Ač, Alexander ; Urban, Otmar
This study investigates the consequences of chronic nitrogen deposition in forests, including its effects on soil and surface water quality, and greenhouse gas emissions. To predict these effects, the authors explore the controls over dissolved and gaseous nitrogen fluxes in temperate forests. Their findings indicate that stream leaching losses of dissolved nitrogen correspond with the nutrient stoichiometry\nof the forest floor, with stream N losses increasing as ecosystems progress towards phosphorus limitation. Soil nitrogen storage increases with oxalate extractable iron and aluminium content. The authors estimate soil gaseous losses based on 15 N stocks, which averaged 2.5±2.2 kg N ha-1 year-1 , comprising 20±14% of total nitrogen deposition. They also extrapolate the current gaseous nitrogen loss flux from forests globally to be 8.9 Tg N year-1 , which represents 39% of current nitrogen deposition to forests worldwide.
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Refinement of the snow cover distribution
Procházka, J. ; Šustková, V. ; Tesař, Miroslav
The study evaluates the importance of automatic snow monitoring stations (ASMS) operated by different subjects in the chosen sub-catchments in the Šumava Mts. in the framework of water reservoir Orlík basin. The attention is paid to the snow cover monitoring as an important water balance component of a basin especially in the mountainous regions. Sub-catchments of the Vltava and Otava rivers represent head water regions of the rainfall windward part of the boarder mountains while Volyňka and Blanice sub-catchments represent leeward inland part of mountains. The importance of ASMS was proved especially in the highest and remote localities of the Šumava Mts. where the basic meteorological stations used for common climatological and hydrological evaluations are missing. The description of the snow cover and its characteristics is possible to improve significantly owing to recent sources and methods. The continual record of the snow cover depth gives for the higher regions of the Šumava Mts. new findings and operational data both for standard climatological evaluations and for further applications used in the framework various institutions, e.g. Czech Hydrometeorological Institute, State Enterprises, etc.
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Instruments for precipitation measurement from history to the present
Lipina, P. ; Procházka, J. ; Tesař, Miroslav
The precipitation amount is one of the most important meteorological elements. It is of fundamental importance for the creation of climatological characteristics, it is the basis of the water balance and the primarily monitored element in the forecasting and warning service. Precipitation measurement has been burdened with many uncertainties for a long time and is therefore consistently given due attention.\nThe first measurement of precipitation in Europe dates back to the 17th century. Regular but not complete measurements of precipitation at Prague's Klementine observatory began in 1752 (continuous series since 1804), in Brno in 1803. In 1817, M.A. David wrote the first guide for observing the weather in Bohemia, published in German, intended for volunteer observers. The activities of institutions and various associations, such as the Prague Klementinum, the Natural Research Society in Brno, the Central Institute for Meteorology and Earth Magnetism and others, had a fundamental influence on the establishment of meteorological stations and precipitation measurements. The Hydrographic Commission for the Kingdom of the Czech Republic and its hydrometric section were founded in 1875 under the leadership of F. J. Studnička E. Purkyně was responsible for the significant expansion of precipitation measurement at that time as part of the construction of a network of forest precipitation measuring stations. \nFor more than 200 years, rain gauges and precipitation measurements have been developed. The Metra 886 manual rain gauge, which has been used for a long time in the Czech lands, was developed according to the Austrian model of prof. Kostlivý. Since 1995, the automation of rainfall measurement was started, first with tipping bucket raingauges, which are gradually being replaced by weighing raingauges. Alternative methods of measuring precipitation are being tested in\nremote and forested areas. This post tries to bring the history, standards and development of precipitation measurement in our country at least as a guide.
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Temperature regime of forest soils
Dohnal, M. ; Votrubová, J. ; Mazúchová, R. ; Blunár, P. ; Tesař, Miroslav
Contribution deals with the monitoring of the temperature regime of forest soils and the soil heat flux at small mountainous basins Liz in the Šumava Mts. and Uhlířská in the Jizera Mts. Soil temperatures are measured with the help of soil moisture meters (Pt100 at Liz basin and CS107 at Uhlířská basin), the soil heat flux is measured with the use of the sensor Hukseflux HFP01. Measured results were statistically evaluated, the analysis of the consistence of the measurement was done and cumulative soil heat fluxes were calculated for the individual hydrological years.
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Palingenesis - the restoration of everything? (Matthew 19,28)
Dus, Jan A
In Matthew’s version of Jesus’ promise (Matthew 19:28–30), in contrast to Mark and Luke, there is no explicit mention of the present time, the restitution of all that the followers of Jesus left behind is thus pushed forward to the future, in which they will take over the reigns with the Son of Man. The promise features the rare term “palingenesis”, whose precise temporal and factual determination cannot be deduced from the sentence itself. While in Mt 19:28 palingenesis is, according to the prevailing interpretation, a synonym for the future restoration of the universe, in Tit 3:5 (the only other occurrence in the NT) the same word refers to the rebirth of some people that took place in the past (at baptism). Even non-biblical literature does not provide a clear precedent - palingenesis tends to be set both in the past and in the future, it concerns both the world and individuals or groups (Israel). – The syntax and punctuation of the Greek sentence show that both interpretations are equally possible: palingenesis can be related either (A) to the following verbal form “sitting (the Son of Man on the throne)”, i.e. to the future, or (B) to the preceding verbal form “following (disciples behind Jesus)”, i.e. into the past, in addition, there is a third, open option (C). In the 16th-century Greek, Latin, and Czech versions, all possibilities are represented: Erasmus punctuates the Vulgate differently (B), Beza first respects the Vulgate (A), but in his Annotations he considers the second solution (B), in the fourth and fifth editions he finally leaves the matter open (C), two Czech translations from the first half of the 16th century (Náměšť 1533, Melantrich 1556/57) hesitate in the dilemma between the Vulgate and Erasmus (C), most Brethren translations starting with Blahoslav (1564) deviate from the Vulgate (B), only the Six-Volume Kralice Bible from 1593/94 (“Kralická Šestidílka”) hesitates (C), in “Kralická Šestidílka” and in the Kralice New Testament from 1601 the Brethren pay equal attention to both interpretations in a rather extensive note, which, for its balance, is a nice proof of intellectual openness and tolerance. Like Beza, the Brethren add a new aspect to interpretation (B): palingenesis can mean the renewal of the whole world thanks to the Gospel and the first coming of the Messiah. – Considering the dynamic development in the 16th century, it is surprising that all ten tracked Czech translations from around the 20th century agree on only one variant (A). Option (B) seems to be in danger of unfair oblivion. Therefore, in conclusion, we allow ourselves to propose a new, somewhat looser translation or paraphrase of verse Mt 19:28 in the spirit of Kralice: “Amen, I say to you, it was you who followed me when I came to renew the world with the gospel, and when the Son of Man sits on the throne of his glory, it will be you again who will sit on twelve thrones and judge the twelve tribes of Israel.”
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Nanoparticels from brake pads wear
Švábenská, Eva ; Roupcová, Pavla ; Friák, Martin ; Schneeweiss, Oldřich
Exposure to particulate air pollution has been associated with a variety of health problems. One of the main\nsources of metal-rich airborne particulate pollution in roadside environments are brake-wear emissions. The \nscanning electron microscopy (SEM) and transmission electron microscopy (TEM), Mössbauer spectroscopy \n(MS), X-ray powder diffraction (XRD) was used to a make quantitative evaluation of wear particles in two \nsamples. Sizes, morphologies, oxidation state, and trace element compositions of wear particles were\ninvestigated using combination of several methods revealed high concentrations of Fe species and phases, \noften associated with carbonaceous material. SEM and TEM observations show that brake wear particles with \na size of tens to hundreds of nm mainly form particle agglomerates. However, ultrafine (<100 nm) particles are \nlikely to pose a health threat after inhalation and/or ingestion.
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Inverse-Heusler Mn2FeSi alloy prepared by powder metallurgy route
Životský, O. ; Skotnicová, K. ; Čegan, T. ; Juřica, J. ; Gembalová, L. ; Zažímal, František ; Jirásková, Yvonna ; Szurman, I.
The Mn2FeSi inverse-Heusler alloy was prepared by solid-state reactions using ball milling for 168 h in n hexane. Two milling procedures varying in the ball-to-powder ratio, namely 4:1 and 10:1, were used to follow \ntheir influence on alloy formation and its physical properties. In both cases no Heusler structure was obtained \ndirectly and therefore the subsequent annealing at 1223 K for 1.5 h in pure Ar was applied. The energy dispersive X-ray analysis resulted in the chemical composition about 49.0-49.9 at% Mn, 25.3-25.6 at% Fe, and \n24.8-25.4 at% Si, in a good agreement with nominal one. X-ray diffraction of both powders confirmed inverse Heusler XA structure of lattice parameters 0.5675 nm (4:1) and 0.5677 nm (10:1), only slightly higher as \ntheoretically obtained 0.560 nm. The presence of minor oxidation phases was also observed in the particle \nstructure of powders. Magnetic properties were analysed at low and room temperatures. Both alloys exhibit \nparamagnetic behaviour at room temperature confirmed by transmission Mössbauer spectroscopy \nmeasurements. Different magnetic behaviour of alloys is observed below 65 K.
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Multi-parameter MTS and SED criterion applied on a crack in an alkali-activated concrete specimen under mixed-mode loading
Malíková, Lucie ; Miarka, Petr ; Šimonová, H.
The paper is devoted to an analysis of a crack propagation in a semi-circular concrete specimen under three-point bending. I+II mixed-mode loading is ensured via an inclined crack. Crack deflection angle is investigated by means of the generalized/multi-parameter form of the Maximum Tangential Stress (MTS) criterion and Strain Energy Density (SED) criterion as well as experimentally. The multi-parameter fracture mechanics concept applied in this work is based on the approximation of the crack-tip stress field by means of the Williams series expansion (WE). It has been proved that this approach can help to describe crack behavior in some kinds of materials better than the classical (one-parameter: stress intensity factor) fracture mechanics. This conclusion is discussed also in this paper.
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PROPERTIES OF NANOCRYSTALLINE FE-NI PARTICLES PREPARED BY THERMAL REDUCTION OF OXALATE PRECURSORS
Švábenská, Eva ; Roupcová, Pavla ; Havlíček, Lubomír ; Schneeweiss, Oldřich
Recent technological advancements require development of cost-effective and high-performance magnets \nwhich ideally do not contain rare earth metals or noble metals. The promising candidates are Fe-Ni-based \nalloys, in particular, the Fe50Ni50 L10 phase (tetrataenite), which has a great perspective for producing hard \nmagnetic materials. Our study explores a promising method for preparing nanoparticles of Fe-Ni alloy from an \niron-nickel oxalate precursor. The coprecipitation method was employed to prepare oxalate precursors, \nfollowed by controlled thermal decomposition in a reducing hydrogen atmosphere. The morphology and \nproperties of the resulting particles were analysed using scanning electron microscopy (SEM) coupled with \nenergy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Mössbauer spectroscopy (MS), and \nmagnetic measurements.\nThe SEM analysis revealed that the particles have approximately cube-shaped unit cell morphology with a\nsize in a range of 1 - 2 μm. Upon annealing, the samples contain multiple phases with varying Fe-Ni content.\nMagnetic measurements confirmed the formation of magnetically suitable Fe-Ni phases in the samples after \nannealing. Mössbauer spectroscopy emerged as a highly effective method for characterizing individual phases \nof the Fe-Ni system.
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Computational and experimental assessment of natural frequencies in a bladed disk system
Mekhalfia, Mohammed Lamine ; Procházka, Pavel ; Maturkanič, Dušan ; Voronova, Evgeniya ; Hodboď, Robert
This paper examines the modal characteristics of a bladed disk in rotating machinery systems using a combination of analytical and experimental modal analysis methods. The analysis involves measuring natural frequencies and mode shapes under different operational conditions. A comparative analysis is conducted to assess modal properties obtained from both analytical and experimental approaches, while also considering the influence of rotation speed. Additionally, Finite Element Method (FEM) outputs are used to accurately position the strain gauge. Integrating these techniques provides a comprehensive understanding of the bladed disk's behaviour under varying rotational speeds, enhancing result accuracy and facilitating thorough investigation within rotating machinery systems.
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