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Composition of Alternative Daily Cover Materials with a Perspective of Use of Latvian Local Resources / Alternatīvo ikdienas pārklājumu materiālu sastāva pētījumi ar perspektīvu Latvijas vietējo zemes dzīļu resursu izmantošanai

Abstract

This paper focuses on alternative daily cover materials intended for use in solid municipal waste landfills. Currently available and proposed cover materials are described by type. The functional contribution of cover components was considered. Special attention was given to alternative daily cover materials in form of sprayable slurries or emulsions. Using the obtained data, conclusions were drawn concerning the most promising components and compositions of sprayable alternative daily covers. Particularly promising components of sprayable daily covers for the use in local environment (Latvia) are clays, which are found in abundance in local mineral deposits.

Open access
Defects of copper patina / Vady mìdìných patin

Abstract

The paper is focused on analyses of dark copper patina defects that were formed on one sheet under the same conditions. Roofs of ten historical buildings were studied by image analysis and samples of two roofs were subjected to more detailed destructive analysis. These samples were studied by means of scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction and infrared spectroscopy. Both types of patina are composed of brochantite. Green patinas consisted of a pure brochantite and they had a fl at and compact surface. Conversely, black patina contained a high degree of impurities (ammonia cations, nitrates, silicates) and the surface was rough. The proportion of dark patina was higher in south and east facing surfaces, where washing by rainfall is more difficult.

Open access
Effect of humic-rich peat extract on plant growth and microbial activity in contaminated soil / Ar humusvielām bagāta kūdras ekstrakta ietekme uz augu augšanu un mikroorganismu aktivitāti piesārņotā augsnē

Abstract

The aim of this work was to compare the effect of 1 % and 5 % humic substances (HS) on the growth of bean, wheat, rape and cress, as well as microbial activity (respiration, enzyme activity) in sandy loam soil spiked with a complex contamination, derived from municipal waste. The results of 23 days pot vegetation experiment demonstrated the stimulating effect of HS on the plant growth and soil microbial activity.

Open access
Effect of Illite Clay Additive on Sintering, Phase Composition and Properties of Mullite-ZrO2 Ceramics / Illītu mālu piedevas ietekme uz mullīta-ZrO2 keramikas saķepšanu, fāžu sastāvu un īpašībām.

Abstract

This study focuses on the influence of illite clay on changes of ZrO2 modifications after sintering and consolidation of mullite-ZrO2 ceramics with or without Y2O3 additive.

It was found that mullite-ZrO2 ceramics both with 4.5 % Y2O3 additive or without it in presence of illite clay tend to have increased densification and compression strength after sintering. Presence of illite clay also promotes change of ZrO2 monoclinic phase to tetragonal phase and the presence of Y2O3 promotes change to ZrO2 cubic phase.

Open access
The Effect of Raw Components on the Densification and Properties of Nanostructured Sialon Materials / Izejas materiālu ietekme uz nanostrukturētu sialona materiālu saķepšanu un īpašībām

Abstract

Two sialon compositions (Y0,33Si10,5Al1,5O0,5N15,5 and Y0,5Si9,5Al2,5O1,0N15,0) were used to determine the effect of starting components on densification and properties of sialon materials. Plasma synthesized nanopowders (Si3N4, AlN, Al2O3, Y2O3 and 73 wt% Si3N4-27 wt%AlN nanocomposite) were used for the investigation. Materials were sintered using traditional or spark plasma sintering methods. Sintering temperature was reduced significantly, if Si3N4-AlN nanocomposite was used as one of the components. The increased amount of asialon phase and higher hardness were characteristic to materials obtained from individual Si3N4, AlN, Al2O3, Y2O3 components.

Open access
Immobilization and Survival of Root Nodule Bacterium Rhizobium leguminosarum Biovar viciae / Gumiņbaktērijas Rhizobium leguminosarum biovar viciae imobilizācija un dzīvotspēja

Abstract

Rhizobium leguminosarum biovar viciae is a bacterium, which can establish nodules on roots of legumes. Rhizobial inoculants are used in agriculture as bio-fertilizers. Peat, clay powder and three kinds of expanded clay were tested for the immobilization of bacteria. The results showed that carrier material influences the success of immobilization and that storage temperature influences the survival. The best results were achieved with maintenance of bacteria in a suspension and immobilization on peat. We recommend storage of rhizobial products at a temperature of −18 °C or 4 °C.

Open access
Mineral Composition and Morphology of Dolocretes of the Devonian Burtnieki and Amata Formations, Latvia / Devona Burtnieku un Amatas svītas dolokrētu minerālais sastāvs un morfoloģija Latvijā

Abstract

Siliciclastic deposits of the Burtnieki Formation and the Amata Formation in Latvia contain carbonate inclusions in places. Morphological peculiarities and mineral composition indicate that these carbonates represent dolocretes formed during subaerial exposure events in Devonian Burtnieki and Amata times. Dolocretes show nodular and veiny structure, circumgranular cracks, and other features of brecciation, but massive dolocretes also have been found in the Amata Formation. These features indicate that the dolocretes formed under the influence of both groundwater activity and pedogenic processes. These dolocretes were formed during episodes of subaerial exposure in repeated processes of drying and wetting either due to fluctuations of the groundwater table or climate change from semi-arid to semi-humid.

Open access
Nedestruktivní zkoušení trubek pomocí metody LFET, UT a ET / Nondestructive testing of tubes using the LFET, UT and ET methods

Dlouhodobým cílem programu řízení životnosti tlakových částí kotlů je eliminace poruchových odstávek a bezpečné provozování těchto zařízení. K detekci kritických blokací ohybů trubek odloupnutými částicemi epitaktické vrstvy byla ve spolupráci s EPRI vybrána metoda LFET (Low Frequency Electromagnetic Testing) a pro měření celkové tloušťky oxidické vrstvy metoda UT (Ultrasonic Testing), které nacházejí uplatnění zejména v USA. Ultrazvukový tloušťkoměr je použitelný pouze pro feritické materiály. Upravená metoda vířivých proudů (ET) bude sloužit ke stanovení tloušťky epitaktické vrstvy na austenitických ocelích.

Open access
Nové mapy korozní agresivity Èeské republiky / Up-dated maps of atmospheric corrosivity for Czech Republic

Atmosférická koroze a klasifi kace agresivity atmosfér je dlouhodobým předmětem studia SVUOM. Ve spolupráci s CGS byly v roce 2001 vytvořeny mapy korozních rychlostí a korozních tříd pro uhlíkovou ocel, patinující ocel, zinek, měď, bronz a hliník. Tento článek uvádí aktuální přístup k modelování atmosférické koroze v České republice, který je založen na modifi kovaných funkcích zahrnujících klimatická data, znečištění ovzduší a nově i vliv rozmrazujících solí v okolí dálnic.

Open access
Parameters influencing the low-cycle fatigue life of materials in pressure water reactor nuclear power plants / Parametry ovlivòující únavové chování materiálù pro tlakovodní jaderné reaktory v režimu nízkocyklové únavy

Abstract

In this literature review we identify and quantify the parameters influencing the low-cycle fatigue life of materials commonly used in nuclear power plants. The parameters are divided into several groups and individually described. The main groups are material properties, mode of cycling and environment parameters. The groups are further divided by the material type - some parameters influence only certain kind of material, e.g. sulfur content may decreases fatigue life of carbon steel, but is not relevant for austenitic stainless steel; austenitic stainless steel is more sensitive to concentration of dissolved oxygen in the environment compared to the carbon steel. The combination of parameters i.e. conjoint action of several detrimental parameters is discussed. It is also noted that for certain parameters to decrease fatigue life, it is necessary for other parameter to reach certain threshold value. Two different approaches have been suggested in literature to describe this complex problem - the Fen factor and development of new design fatigue curves. The threshold values and examples of commonly used relationships for calculation of fatigue lives are included. This work is valuable because it provides the reader with long-term literature review with focus on real effect of environmental parameters on fatigue life of nuclear power plant materials.

Open access