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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
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
Physicochemical Pretreatment of Contaminated Microfibre Cloths after Their Use in Waterless Car Wash / Ar virsmas aktīvām vielām piesārņotu bezūdens automašīnu tīrīšanas mikrošķiedru audumu fizikāli-ķīmiskā priekšapstrāde.

Abstract

Contaminated microfibre cloths (80 % polyester and 20 % polyamide) which were previously used in waterless car cleaning process were treated in ultrasonic bath. Efficiency of water, ethanol, 2-propanol and ethylene glycol as liquid phase for ultrasonic treatment was compared. Chemical oxygen demand (COD), concentration of surfactants and total nitrogen in the extract were tested after 0 min, 10 min, 30 min and 60 min ultrasonic (US) exposure (42 kHz). In all cases the COD values gradually increased in a time dependent manner from 6 % to 35 % with ethanol, from 17 % to 37 % with ethyleneglycol and from 17 % to 33 % with 2-propanol at 10 to 60 min US mode, respectively.

Open access
Porous Cordierite Ceramics from Natural Clays / Poraina kordierīta keramika no dabiskiem māliem

Abstract

In this report the obtaining and properties of hightemperature porous ceramic materials using local carbonate clays and quartz sand resources was studied. Materials with two different porosities were obtained by using different synthesis temperatures. The test results show that these materials contain cordierite as their main crystalline phase. The porosity directly influences the compressive strength and it is greatly reduced when overall porosity increases. The CTE of obtained materials is low − about 3-10−6 1/°C.

Open access
Properties of the Jurassic Clayey Deposits of Southwestern Latvia and Northern Lithuania / Dienvidrietumu Latvijas un Ziemeļlietuvas juras mālaino nogulumu īpašības

Abstract

Jurassic clay rich in organic matter from western Latvia is known already from early 19th century. Jurassic clays provide an interest because of high potential for innovative use due to its clay mineral composition jointly with organic material. Properties of the Jurassic clayey deposits were studied by using various physical and chemical methods. Material gained from field was tested by modern techniques such as UV-Vis, 3D fluorescence and FTIR - spectra, which show patterns of organic compounds in the clay material. AAS analyses characterized inorganic content. PXRD studies raised discussions about the origin of kaolin, illite and smectite and interactions among these clay minerals. Obtained results show that Jurassic clays with organic matter have future potential for possible use in cosmetic industry and as a sorbent material.

Open access
Solid Phase Extraction of Bryophyte Lipids / Briofītu lipīdu cietfāzes ekstrakcijas frakcionēšana

Abstract

A simple, fast and reproducible analytical method for fractionation of freely available bryophyte lipids was developed. Lipid fractionation was achieved by solid phase extraction using porous silica and silica derivatized with -NH2 groups and the compounds were quantified as their trimethylsilyl derivatives by gas chromatography-mass spectrometry. The suggested fractionation method allows to identify several groups of substances prospective in respect of search of new biologically active compounds in bryophytes as well as in respect of understanding of their metabolism.

Open access