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Number of results: 51
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Abstract

During austral summer 1978/1979 the content of dissolved oxygen, phosphates, nitrates and nitrites was determined in the waters of Admiralty Bay. Environmental conditions prevailing in Admiralty Bay are compared with the conditions in the open Antarctic waters.

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Authors and Affiliations

Ryszard Samp
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Abstract

The oxygen and chlorophyll a contents. pH, temperature and transparency were studied in Lake Rzuno in the period from June 1998 - September I 999. This lake has a very strong thermal stratification and weaker oxygenic stratification. The degree of surface water saturation with oxygen was rather small (max. 136%) but the oxygen conditions in the whole Lake Rzuno were good because the total lack of oxygen is noted only in summer and only below 20 m depth. Whereas during autumn and spring circulation the oxygen concentration reaches 5 mg O, drn' al the bottom. The correlation between visibility of Secchi disc and chlorophyll a concentration featured high correlation indicator (r = -0.87). The awerage water transparency, low oxygen deficit and small changes in water reaction show that this lake has moderate eutrophic character.
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Authors and Affiliations

Jan Trojanowski
Janusz Bruski
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Abstract

In this paper a 600 MW oxy-type coal unit with a pulverized bed boiler and a membrane-cryogenic oxygen separator and carbon capture installation was analyzed. A membrane-cryogenic oxygen separation installation consists of a membrane module and two cryogenic distillation columns. In this system oxygen is produced with the purity equal to 95%. Installation of carbon capture was based on the physical separation method and allows to reduce the CO2emission by 90%. In this work the influence of the main parameter of the membrane process – the selectivity coefficient, on the efficiency of the coal unit was presented. The economic analysis with the use of the break-even point method was carried out. The economic calculations were realized in view of the break-even price of electricity depending on a coal unit availability.

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Authors and Affiliations

Janusz Kotowicz
Sylwia Berdowska
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Abstract

The oxygen and thermal conditions in Lake Ińsko were examined in years 1999-2000. Lake Ińsko is one of a dynamictic type and its waters are mixed twice a year. This lake has a strong thermal and oxygen stratification. The oxygen conditions in the lake are very good because the total deficiency of oxygen appears only in summer, on the depth below 30 m, and only in the areas where the influence of town of Ińsko is the strongest. During autumn and winter circulation the concentration of oxygen near the bottom reaches 5 mg O2 dm-3. The concentration of oxygen in the water reflects favorable conditions of biomass production, including primary production of phytoplankton in epilimnion of Lake Ińsko. The intensive development of algas has considerably influenced the transparency of water. On the background of vertical thermal and oxygen differences during the summer there were also differences in the reactions of water.
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Authors and Affiliations

Jan Trojanowski
Agnieszka Parzych
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Abstract

The concentration or the partial pressure of oxygen in an environment can be determined using different measuring principles. For high temperature measurements of oxygen, ceramic-based sensors are the most practical. They are simple in construction, exploration and maintenance. A typical oxygen potentiometric sensor consists of an oxygen ion conducting solid electrolyte and two electrodes deposited on the two sides of the electrolyte. In this paper different structures of potentiometric oxygen sensors with a solid state reference electrode were fabricated and investigated. The fabricated structures consisted of oxygen ion conducting solid electrolyte from yttria stabilized zirconia, a sensing platinum electrode and nickel-nickel oxide reference electrode. The mixture of nickel-nickel oxide was selected as the reference electrode because it provides reliable electrochemical potential in contact with oxygen conducting electrolyte. To avoid oxidation of nickel the reference electrode is sealed from ambient and the mixture of nickel-nickel oxide was formed electrochemically from nickel oxide after sealing. The effectiveness of the sealing quality and the effectiveness of nickel-nickel oxide mixture formation was investigated by impedance spectroscopy.

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Authors and Affiliations

Katarzyna Dunst
Grzegorz Jasiński
Piotr Jasinski
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Abstract

The use of hyperbaric oxygen therapy (HBOT) is an accepted method of supporting wound healing in human medicine. Yet, because of the risk of complications associated with HOBT, a safer modification of the therapy, known as L-HOBT (lower pressure and lower oxygen concen- tration), is increasingly used nowadays. Therefore, due to the lack of literature reports regarding the clinical use of L-HBOT in animals, the authors decided to present the results of L-HBOT supportive treatment of postoperative wounds after hemimastectomy compared to classic treat- ment. The study group included 12 bitches divided into two groups: group A (assisted L-HBOT) and group B (classic treatment). In addition to conventional treatment, the supportive therapy included 1.5 hours of hyperbaric chamber therapy for 5 consecutive days, starting 24 hours after surgery (1500hPa pressure and 26% oxygen concentration in the chamber). The patients were followed and evaluated throughout the course of the treatment by two independent doctors. The results of the treatment revealed no negative clinical impact of L-HOBT supportive therapy on the body of the animals. At the same time, postoperative wounds after L-HOBT healed faster and with fewer postoperative complications compared to the control group. This resulted in a shorter treatment period, terminating with an earlier skin suture removal.

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Authors and Affiliations

W. Łunkiewicz
Z. Kiełbowicz
K. Kalisiak
K. Tuliński
P. Prządka
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Abstract

The restoration of the anthropogenic Pławniowice water reservoir with the hypolimnion withdrawal method (the Olszewski's tube) began in December 2003. The decision to restore the reservoir had been taken due to its terrible condition resulting from the hypertrophy, which had been indicated by the research from the years 1993–1998.

The following paper presents the results of eight-year-long research into the formation of oxygen conditions and restoration settings. They were compared with the data obtained from the research before the restoration. Positive changes were witnessed. It was showed that grasping the changes in oxygen conditions enables the comparison of oxygen profiles in the same months in subsequent years. The ratio of anoxic water layer thickness to the oxygenated layer thickness was suggested as a factor characterizing oxygen conditions. The area described with an izooxa in the xy coordinate system was suggested as a factor [O2 mg/m2] allowing researchers to understand and describe occurring changes. It was observed that the oxygen solved in water as a result of the restoration occurred in the whole water column in the third decade of July. The oxygen concentration in the hypolimnion gradually rose in May, June and July each year. It was showed that the improvement in oxygen conditions stemmed from progressing oligotrophy of the reservoir.

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Authors and Affiliations

Maciej Kostecki
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Abstract

The paper presents the results of studies of sanitary microorganisms' vertical distribution in pelagial and profundal waters of Lake Wigry against the background of thermal-oxygen relations and the presence of a chosen chemical compound in the annual cycle. Total Viable Count at 20°C (TYC 20°C) and Total Viable Count at 37°C (TYC 37°C) were used as indicators of pollution, while Total Coli (TC), Faecal Coli (FC) and Faecal Streptococcus-Enterococcus (FS) - as indicators of the sanitary state. Water samples were collected from 3 sites situated in the centre of the lake. Pelagial and profundal waters showed a little degree of pollution. Higher bacteriological pollution was found in some of waters samples from Lake Wigry at site I in the vicinity of the mouth of the Czarna Hańcza River. The most numerous sanitary microorganisms were detected at the deep from I to 5 meters and above the bottom sediments. Number of FC bacteria was only higher at the depth of 5 meters and deeper. An important positive correlation was noted between temperature and TYC 20°C as well as TYC 37°C, while negative between TC also FC during the whole study period. The oxygen content was correlated negative with TYC 20°C, TYC 37°C and FS. The depth was correlated negatively with TYC 20°C only.
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Authors and Affiliations

Ewa Korzeniewska
Anna Gotkowska-Płachta
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Abstract

Biochemical Oxygen Demand (BOD) is an important factor used to measure water pollution. This article reviews recent developments of microbial biosensors with respect to their applications for low BOD estimation. Four main methods to measure BOD using a biosensor are described: microbial fuel cells, optical methods, oxygen electrode based methods and mediator-based methods. Each of them is based on different principles, thus a different approach is required to improve the limit of detection. A proper choice of microorganisms used in the biosensor construction and/or sample pre-treatment processes is also essential to improve the BOD lower detection limit.

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Authors and Affiliations

Elżbieta Malinowska
Łukasz Górski
Kamil F. Trzebuniak
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Abstract

The research analyzed seasonal changes of the oxygen regime and related indicators on the example of water objects of the Ukrainian Polesie Region. The region shows different directions of economic use. Zebrafish ( Danio rerio Hamilton–Buchanan) and the Prussian carp ( Carassius auratus gibelio Bloch) were used as test objects to investigate survival responses. Dissolved oxygen (DO) concentration in water, pH values and temperatures were determined by standard methods. Based on research results, the main problems were determined pertaining to the oxygen regime of investigated waters, i.e. the increase in temperature and toxicity of the aquatic environment in the summer. A rather dangerous decrease in DO concentration, almost up to the levels of maximum allowable concentration (MAC) (4.10 mg∙dm–3 in group E1 and 6.07 mg∙dm–3 in group E2), was observed in August and it was typical for the reservoirs with a slow water movement. Flowing river waters (group E3) were eliminated due to their better aeration compared to other groups. The correlation analysis based on the presented data revealed a high and average degree of probable correlation between the DO concentration and water temperature, as well as an average degree of correlation with general toxicity determined on sensitive species of D. rerio, and in group E1 on the persistent species C. auratus gibelio as well. The interrelations and equations of the rectilinear regression can be used to predict the oxygen regime of the waters investigated and other surface waters having similar problems.
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Authors and Affiliations

Ella O. Aristarkhova
1
ORCID: ORCID
Tetiana P. Fedoniuk
2
ORCID: ORCID
Ludmila D. Romanchuk
1
ORCID: ORCID
Sergii V. Latushynskyi
1
ORCID: ORCID
Iryna V. Kot
1
ORCID: ORCID

  1. Polissia National University, Faculty of Forestry and Ecology, Zhytomyr, Ukraine
  2. Polissia National University, Educational and Scientific Center of Ecology and Environmental Protection, Staryi Blvd, 7, Zhytomyr, Zhytomyrs'ka oblast, 10008 Ukraine
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Abstract

Deoxidation of steel with carbon under reduced pressure is often used for increasing the steel purity. Suitable units for this purpose in

foundries are vacuum induction furnaces. Possibilities of increasing the steel purity by deoxidation with carbon in the vacuum induction

furnace were studied for the steel for the petrochemistry of specific composition 25Cr/35Ni. The charge composed of the return material

only was melted in the air. During melting the charge oxidized and the oxidizing slag formed. Chemical composition of steel, morphology,

chemical composition of inclusions in the steel and chemical composition of slag after vacuuming were studied on the basis of samples

taken before and after vacuuming. Temperature and oxygen activity were measured before and after vacuuming. Globular inclusions with

dominant content of silicon and manganese were observed in steel before and after vacuuming. Contents of total oxygen in steel didn’t

change significantly during vacuuming. On the basis of composition of inclusions and measured oxygen activity the activity of Cr2O3

in

inclusions was calculated. A slag sample was taken after vacuuming and equilibrium oxygen activity in steel with regard to the Cr2O3

content in the slag was estimated from the slag composition. Equilibrium oxygen activity in relation to the Cr2O3 content in the slag was

higher than equilibrium activity measured in the steel. For this reason it is not possible, under the studied conditions, to decrease oxygen

content in steel during vacuuming.

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Authors and Affiliations

J. Šenberger
V. Pernica
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Abstract

Parameters of surface acoustic waves (SAW) are very sensible to change of physical conditions of a propagation medium. In the classical theory formulation, the waves are guided along the boundary of semi-infinity solid state and free space. A real situation is more complex and a medium commonly consists of two physical components: a solid substrate and a gaseous or liquid environment. In the case of stress-free substrate, the strongest impact on SAW properties have surface electrical and mechanical conditions determined by solids or liquids adhering to the boundary. This impact is utilised for constructing sensors for different gases and vapours e.g. (Jakubik et al., 2007; Hejczyk et al., 2011; Jasek et al., 2012). The influence of gaseous environment on the SAW properties is usually very weak and ignored. However, in certain condition it can be significant enough to be applied to sensor construction. In general, it concerns Rayleigh wave devices where energy leakage phenomenon is perceptible, especially when the gas being detected considerably changes the density of environment. The paper presents the results of experiments with oxygen-nitrogen mixture. Their primary aim was focused on finding the dependence of resonant frequency and attenuation in SAW resonator on parameters and concentrations of the gas in the environment.

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Authors and Affiliations

Mateusz Pasternak
Krzysztof Jasek
Michał Grabka
Tomasz Borowski
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Abstract

Operations conducted by petroleum industry generate an entire range of drilling waste. The chemical composition of drilling waste and its toxicity depend primarily on the geological and technological conditions of drilling, the type of drilled rock deposits and on the type and composition of the drilling mud used. In the course of drilling operations, drilling fluids are in constant contact with bacteria, fungi and other organisms infecting the mud. Pioneer species, capable of surviving and using the resources of this specific environment, are selected. For this reason, the effectiveness of microbiota survival on different types of spent drilling muds and in different dilutions with brown soil was measured. Spent drilling muds samples came from drilling operations in various regions of Poland, e.g. Subcarpathia, the Polish Lowland and Pomerania regions. Oxygen consumption after 96 h was around 20 μg·g‒1 dry mass in soil or soil/drilling water-based mud mixture. Soil mixes contained 10 wt% synthetic base, mud had a higher oxygen consumption – 38 μg · g‒1 dry mass. Oxygen consumption decreases sharply as the content of the spent synthetic base mud fraction increases. A higher concentration of spent SBM (35 wt%) reduced the aerobic metabolism by slightly more than 50%. A high concentration of reduced carbon decreased the respiratory quotient (RQ) value to 0.7. All the researched drilling waste shows microbiological activity. At the full concentration of drilling fluids and non-dilution options, the chemical composition (salinity, inhibitors, etc.) strongly inhibits microbiota development and consequently, respiration

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Authors and Affiliations

Aleksandra Jamrozik
1
Roman Żurek
2
Andrzej Gonet
1
ORCID: ORCID
Rafał Wiśniowski
1

  1. AGH University of Science and Technology, Poland
  2. Polish Academy of Sciences, Institute of Nature Conservation, Poland
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Abstract

Allelopathy refers to the beneficial and detrimental effects of one plant on another plant in both crops and weeds through the production of secondary compounds. In order to evaluate the allelopathic effects of wheat ( Triticum aestivum L.) as a crop and redroot pigweed ( Amaranthus retroflexus L.) as a common weed worldwide on each other in intercropping, these plants were cultivated under controlled conditions at Tabriz University laboratory. The ratios of wheat to redroot pigweed were, 100 : 0 and vice versa as a control, 75 : 25, 50 : 50, and 25 : 75. The results showed that at the ratio of 25 : 75 (wheat : redroot pigweed), the fresh and dry weight of roots and shoot length of wheat decreased significantly compared to the control. The fresh and dry weight of wheat shoots showed a significant decrease at different ratios compared to the control. Shoot peroxidase (POD), root superoxide dismutase (SOD), and root and shoot catalase (CAT) activities in redroot pigweed increased in all intercropping ratios compared to the control. POD activity in wheat roots was higher at all ratios than in the control. Furthermore, the ratio of 75 : 25 (wheat : redroot pigweed) led to increased activity of POD enzymes and malonedialdehyde (MDA) content in wheat shoots. Moreover, roots of redroot pigweed showed increased activity of ascorbate peroxidase (APX) and SOD enzymes and MDA content. With increased density of redroot pigweed, the soluble sugar content of wheat roots reduced significantly. However, the content of insoluble sugar and total protein increased. Root exudate compounds such as terpenoids, phenolic compounds, fatty alcohol, steroids, fatty acids, and alkanes were identified using gas chromatography/mass spectrometry (GC/MS). The findings showed that the roots were more exposed to oxidative stress due to direct contact with allelochemical compounds. Our results support the hypothesis that increasing the density can reduce the toxicity of allelochemical compounds and that increasing the activity of the antioxidant system will improve plant growth under allelochemical stress.
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Authors and Affiliations

Zahra Alizadeh
1
ORCID: ORCID
Rouhollah Motafakkerazad
1
ORCID: ORCID
Seyed Yahya Salehi-Lisar
1
Gholamreza Zarrini
2

  1. Plant, Cell and Molecular Biology Department, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
  2. Animal Biology Department, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
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Abstract

Protective coatings have direct contacts with hot and liquid alloys. As the result of such contacts gases are emitted from coatings. Gas forming is a tendency of the tested material to emit gases under a temperature influence. In order to assess the gas forming tendency either direct or indirect methods are applied. In the hereby work, the measurements of the gas forming tendency were performed under laboratory conditions, by means of the developed indirect method. The research material constituted samples of six selected protective coatings dissolved either in alcohol or in water. These coatings are applied in sand moulds and cores for making cast iron castings. The assessment of their gas forming tendency was presented in relation to temperatures and heating times. The occurrence and changes of oxygen and hydrogen contents in gases outflowing from the measuring flask during tests, were measured by means of gas sensors. The process of the carbon monoxide (CO) emission during tests was also assessed. The following gas sensors were installed in flow-through micro chambers: for oxygen - lambda probe, for hydrogen – pellistor, for carbon monoxide - sensor (dedicated for CO) FIGARO TGS 822 TF. The results of direct CO measurements were recalculated according to the algorithm supplied by the producer of this sensor.
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Bibliography

[1] Di Muoio G.L., Skat Tiedje N., Budolph Johansen B. (2014). Automatic vapour sorption analysis as new methodology for assessing moisture content of water based foundry coating and furan sands. Mar del Plata, BS. As., Argentina
[2] Nwaogu, U. & Tiedje, N. (2011). Foundry coating technology: A Review. Materials Sciences and Applications. 2(8), 1143-1160. DOI: 10.4236/msa.2011.28155.
[3] Scarber Jr, P., Bates, C. & Griffin, J. (2006). Avoiding gas defects through mold and core package design. Modern Casting. 96(12), 38-40.
[4] Zych, J, Mocek, J. (2019). Thermal Volumetric Analysis (TVA): a new test method of the kinetics of gas emissions from moulding sands and protective coatings heated by liquid alloy. London: IntechOpen, 13-33. ISBN: 978-1- 78985-161-8; e-ISBN: 978-1-78985-162-5. https://www.intechopen.com/chapter/pdf-download/62133.
[5] Z.B.P. SENSOR GAZ Andrzej Rejowicz. Explosimetric sensing head. Retrieved January 15, 2021 from http://sensorgaz.com.pl/wp-content/uploads/2017/06/EKP1WH.pdf
[6] Figaro Engineering Inc. Tentative product information TGS822TF. Retrieved January 15, 2021 from https://cdn.sos.sk/productdata/ad/97/a7c71525/tgs-822tf.pdf
[7] HA International. Refractory Coating Products. Retrieved January 15, 2021 from https://www.ha.international.com/content/products/refractory _coatings/refractory_coatings.aspx
[8] Marć, A.W. (2018). Multi-parameter assessment of gas formation of selected protective coatings for sand forms. Master thesis. Kraków: AGH WO. (in Polish).
[9] Mocek, J. (2019). Multiparameter assessment of the gas forming tendency of foundry sands with alkyd resins. Archives of Foundry Engineering. 19(2), 41-48.
[10] Zych, J., Mocek, J. & Snopkiewicz, T. (2014). Gas generation properties of materials used in the sand mould technology – modified research method. Archives of Foundry Engineering. 14(3), 105-109.
[11] Lewandowski, J.L., Solarski, W. & Pawłowski, Z. (1993). Classification of molding and core sands in terms of gas formation. Przegląd Odlewnictwa. 5, 143-149. (in Polish).
[12] Lewandowski, J.L. (1997). Foundry mold materials. Kraków. (in Polish).
[13] Mocek, J. & Chojecki, A. (2009). Evolution of the gas atmosphere during filing the sand moulds with iron alloys. Archives of Foundry Engineering. 9(4), 135-140.
[14] Pietkun-Greber I. Janka R. (2010). Effect of hydrogen on metals and alloys. Proceedings of EC Opole. 4(2), 471-476. (in Polish).
[15] Bobrowski, A., Holtzer, M., Dańko, R. & Żymankowska-Kumon S. (2013). Analysis of gases emitted during a thermal decomposition of the selected phenolic binders. Metalurgia International. 18(si.7), 259-261.
[16] Holtzer, M., Kwaśniewska-Królikowska, D., Bobrowski, A., Dańko, R., Grabowska, B., Żymankowska-Kumon, S., & Solarski, W. (2012). Investigations of a harmful components emission from moulding sands with bentonite and lustrous carbon carriers when in contact with liquid metals. Przegląd Odlewnictwa. 62(3-4), 124-132.
[17] Holtzer, M., Dańko, R., Kmita, A., Drożyński, D., Kubecki, M., Skrzyński, M., Roczniak, A. (2020). Environmental Impact of the Reclaimed Sand Addition to Molding Sand with Furan and Phenol-Formaldehyde Resin-A Comparison. Materials. 13, 4395, 1-12. DOI: 10.3390/ma13194395 www.mdpi.com/journal/materials.
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Authors and Affiliations

J. Mocek
1

  1. AGH University of Science and Technology, Faculty of Foundry Engineering, Department of Moulding Materials, Mould Technology and Cast Non-Ferrous Metals, Al. Mickiewicza 30, 30-059 Kraków, Poland
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Abstract

The first recognition of a tracemaker responding to a temporary shift in the redox boundary is recognized. This is recorded by a new trace fossil, Sursumichnus orbicularis igen. et isp. nov., which is established for mound-like structures on the upper surfaces of sandstone beds from the Borjomi Flysch (upper Paleocene–lower Eocene) in the Lesser Caucasus (Georgia). It is connected with the spatangoid echinoid burrow Scolicia de Quatrefages, 1849 and interpreted as a resting trace of the same tracemaker produced after moving up from a deeper position within the sediment. The resting is caused by an episode of unfavourable conditions related to shallowing of the redox boundary. The trace fossil is a component of the Nereites ichnofacies.
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Authors and Affiliations

Alfred Uchman
1
Zurab Lebanidze
2
Nino Kobakhidze
3
Tamar Beridze
3
Davit Makadze
4
Koba Lobzhanidze
3
Sophio Khutsishvili
3
Rusudan Chagelishvili
5
Kakha Koiava
2
Nino Khundadze
4

  1. Faculty of Geography and Geology, Institute of Geological Sciences, Jagiellonian University, Gronostajowa3a, 30-387 Kraków, Poland
  2. Department of Geology, Faculty of Exact and Natural Sciences, Iv. Javakhishvili Tbilisi State University, University str. 13, 0186 Tbilisi, Georgia
  3. Alexander Janelidze Institute of Geology, Iv. Javakhishvili Tbilisi State University, Politkovskaia 31, 0186 Tbilisi, Georgia
  4. Alexander Tvalchrelidze Caucasian Institute of Mineral Resources, Tbilisi State University, 12 Mindeli str., 0186 Tbilisi, Georgia
  5. Department of Geology and Paleontology, Georgian National Museum, 3 Purtseladze str., 0105 Tbilisi, Georgia
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Abstract

Tin dioxide (SnO2) is an n-type semiconductor and has useful characteristics of high transmittance, excellent electrical properties, and chemical stability. Accordingly, it is widely used in a variety of fields, such as a gas sensor, photocatalyst, optoelectronics, and solar cell. In this study, SnO2 films are deposited by thermal atomic layer deposition (ALD) at 180°C using Tetrakis(dimethylamino)tin and water. A couple of 5.9, 7.4 and 10.1nm-thick SnO2 films are grown on SiO2/Si substrate and then each film is annealed at 400°C in oxygen atmosphere. Current transport of SnO2 films are analyzed by measuring current – voltage characteristics from room temperature to 150°C. It is concluded that electrical property of SnO2 film is concurrently affected by its semiconducting nature and oxidative adsorption on the surface.

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Authors and Affiliations

Seong Yu Yoon
Byung Joon Choi
ORCID: ORCID
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Abstract

The organic carbon (OC)-rich, black shale succession of the Middle Triassic Bravaisberget Formation in Spitsbergen contains scattered dolomite-ankerite cement in coarser-grained beds and intervals. This cement shows growth-related compositional trend from non-ferroan dolomite (0–5 mol % FeCO3) through ferroan dolomite (5–10 mol % FeCO3) to ankerite (10–20 mol % FeCO3, up to 1.7 mol % MnCO3) that is manifested by zoned nature of composite carbonate crystals. The d13C (-7.3‰ to -1.8‰ VPDB) and d18O (-9.4‰ to -6.0‰ VPDB) values are typical for burial cements originated from mixed inorganic and organic carbonate sources. The dolomite-ankerite cement formed over a range of diagenetic and burial environments, from early post-sulphidic to early catagenic. It reflects evolution of intraformational, compaction-derived marine fluids that was affected by dissolution of biogenic carbonate, clay mineral and iron oxide transformations, and thermal decomposition of organic carbon (decarboxylation of organic acids, kerogen breakdown). These processes operated during Late Triassic and post-Triassic burial history over a temperature range from approx. 40°C to more than 100°C, and contributed to the final stage of cementation of the primary pore space of siltstone and sandstone beds and intervals in the OC-rich succession.

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Authors and Affiliations

Krzysztof P. Krajewski
Ewa Woźny
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Abstract

Samples for the study were collected from, known from the literature, outcrop profiles in Zarzecze, Radymno, Dybawka, Tarnawce and Pikulice-Nehrybka, situated at the Carpathian border, in the vicinity of the Przemyśl town, close to the San River valley (SE Poland). They represent the Vistulian loess-palaeosol sequences. Carbonates occur mainly in the loesses representing OIS 2 and 3. Pollen analysis, carried out for two profiles (Tarnawce, Radymno), throws light on palaeoecological conditions of loess cover formation and transformation.Isotopic analysis of authigenic carbonates was carried out on carbonate cemented bodies dispersed throughout the loess in forms of nodule, rhizolith and rhizocretion and on bioclasts, mainly snail shells, ostracod valves, and sparse globules (probably the internal shells of the naked snails).In the successions studied, the upper Vistulian loess deposited in environment with poor vegetation, contains rhizo- liths and rhizocretions mainly, while in the middle and lower Vistulian loess with well developed soils, gley horizons, and intercalations of subaqueous sediments, remains of snail shells and ostracod valves prevail. The two main forms of carbonates differ markedly in isotopic composition from one another. These differences seem to be more important than those between samples of one form of carbonates along particular sections. That is the result of numerous factors affecting the fractionation of carbon and, in particular, oxygen stable isotopes in the environment of precipitation of authigenic calcite. The isotopic composition of carbonates cementing sediments is controlled mainly by biominerali- zation of organic matter and local climatic parameters which were rather slightly differentiated during the formation of the studied sediments. The d13C values for bioclasts vary in a broader range than for calcitic cements. Usually the snail shell carbonate is more enriched with heavier carbon isotope than that from ostracod valves, resulting from the isotopic equilibrium with precipitation and with surface waters, respectively. Basing on our study we can conclude that fluctuations of isotope composition of authigenic carbonates make it hard to apply as a paleoclimatic indicator. However, the general trend of d18O variation in analysed carbonate fractions from leoss-palaeosol sequences displays some connections with climatic fluctuations.

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Authors and Affiliations

Bożena Łącka
Maria Łanczont
Maryna Komar
Teresa Madeyska
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Abstract

Laboratory works on combustion of some organic compounds as air pollutants in presence of platinum, palladium and manganese catalysts at various oxygen concentrations were carried out. Several mixtures of nitrogen and oxygen contained vapours of hexane, isooctane, methanol, acetone ethyl acetate and toluene were examined. The experimental results show that conversion efficiency of 95% might be reached, despite of oxygen concentration decreasing to 5%.
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Authors and Affiliations

Walter Mucha
Jan Konieczyński
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Abstract

Silver nanoparticles (AgNPs) are widely used in numerous industries and areas of daily life, mainly as antimicrobial agents. The particles size is very important, but still not suffi ciently recognized parameter infl uencing the toxicity of nanosilver. The aim of this study was to investigate the cytotoxic effects of AgNPs with different particle size (~ 10, 40 and 100 nm). The study was conducted on both reproductive and pulmonary cells (CHO-9, 15P-1 and RAW264.7). We tested the effects of AgNPs on cell viability, cell membrane integrity, mitochondrial metabolic activity, lipid peroxidation, total oxidative and antioxidative status of cells and oxidative DNA damage. All kinds of AgNPs showed strong cytotoxic activity at low concentrations (2÷13 μg/ml), and caused an overproduction of reactive oxygen species (ROS) at concentrations lower than cytotoxic ones. The ROS being formed in the cells induced oxidative damage of DNA in alkaline comet assay. The most toxic was AgNPs<10 nm. The results indicate that the silver nanoparticles, especially less than 10 nm, may be harmful to the organisms. Therefore, risk should be considered when using nanosilver preparations and provide appropriate protective measures when they are applied.

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Authors and Affiliations

Lidia Zapór
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Abstract

In this paper the results of the thermodynamic analysis of the oxy-combustion type pulverized bed boiler integrated with a hybrid, membrane- cryogenic oxygen separation installation are presented. For the calculations a 600 MW boiler with live steam parameters at 31.1 MPa /654.9 oC and reheated steam at 6.15 MPa/672.4 oC was chosen. In this paper the hybrid membrane-cryogenic technology as oxygen production unit for pulverized bed boiler was proposed. Such an installation consists of a membrane module and two cryogenic distillation columns. Models of these installations were built in the Aspen software. The energy intensity of the oxygen production process in the hybrid system was compared with the cryogenic technology. The analysis of the influence of membrane surface area on the energy intensity of the process of air separation as well as the influence of oxygen concentration at the inlet to the cryogenic installation on the energy intensity of a hybrid unit was performed.
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Authors and Affiliations

Sylwia Berdowska
Anna Skorek-Osikowska
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Abstract

The aim of the presented research was to test different carbon supports, such as graphene oxide (GO), graphene oxide modified with ammonia (N-GO), and reduced graphene oxide (rGO) for catalysts used in a low-temperature fuel cell, specifically a proton exchange membrane fuel cell (PEMFC). Modification of the carbon supports should lead to different catalytic activity in the fuel cell. Reduction of GO leads to partial removal of oxygen groups from GO, forming rGO. Modification of GO with ammonia results in an enrichment of GO structure with nitrogen. A thorough analysis of the used supports was carried out, using various analytical techniques, such as FTIR spectroscopy and thermogravimetric (TGA) analysis. Palladium and platinum catalysts deposited on these supports were produced and used for the oxygen reduction reaction (ORR). Catalytic activity tests of the prepared catalysts were carried out in a home-made direct formic acid fuel cell (DFAFC). The tests showed that the enrichment of the GO structure with nitrogen caused an increase in the catalytic activity, especially for the palladium catalyst. However, reduction of GO resulted in catalysts with higher activity and the highest catalytic activity was demonstrated by Pt/rGO, because platinum is the most catalytically active metal for ORR. The obtained results may be significant for low-temperature fuel cell technology, because they show that a simple modification of a carbon support may lead to a significant increase of the catalyst activity. This could be useful especially in lowering the cost of fuel cells, which is an important factor, because thousands of fuel cells running on hydrogen are already in use in commercial vehicles, forklifts, and backup power units worldwide. Another method used for lowering the price of current fuel cells can involve developing new clean and cheap production methods of the fuel, i.e. hydrogen. One of them employs catalytic processes, where carbon materials can be also used as a support and it is necessary to know how they can influence catalytic activity.

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Authors and Affiliations

Zuzanna Bojarska
Marta Mazurkiewicz-Pawlicka
Łukasz Makowski
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Abstract

Results of the studies for determining fractions of organic contaminants in a pretreated petrochemical wastewater flowing into a pilot Aerated Submerged Fixed-Bed Biofilm Reactor (ASFBBR) are presented and discussed. The method of chemical oxygen demand (COD) fractionation consisted of physical tests and biological assays. It was found that the main part of the total COD in the petrochemical, pretreated wastewater was soluble organic substance with average value of 57.6%. The fractions of particulate and colloidal organic matter were found to be 31.8% and 10.6%, respectively. About 40% of COD in the influent was determined as readily biodegradable COD. The inert fraction of the soluble organic matter in the petrochemical wastewater constituted about 60% of the influent colloidal and soluble COD. Determination of degree of hydrolysis (DH) of the colloidal fraction of COD was also included in the paper. The estimated value of DH was about 62%. Values of the assayed COD fractions were compared with the same parameters obtained for municipal wastewater by other authors.

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Authors and Affiliations

Włodzimierz Wójcik
Karol Trojanowicz

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