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Wyświetlanie 1-9 z 9
Tytuł:
Activated bio-carbons prepared by physical activation of residues after supercritical extractionof raw plants
Autorzy:
Bazan-Woźniak, Aleksandra
Pietrzak, Robert
Powiązania:
https://bibliotekanauki.pl/articles/110368.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
bio-sorbents
physical activation
toxic gas removal
adsorption from liquid phase
Langmuir and Freundlich isotherm
Opis:
A series of activated bio-carbons has been obtained by physical activation of residues after supercritical extraction of blackberries, raspberries and blackcurrants. The effects of different temperatures of activation and different starting materials on the physicochemical and sorption properties of the bio-carbon samples obtained were evaluated. The physicochemical properties of the activated bio-carbons were characterized by elementary analysis, low-temperature nitrogen sorption and Boehm titration. All materials were tested as adsorbents of pollutants from gas (nitrogen dioxide) and liquid (iodine, methylene blue) phase. The sorption properties of the activated bio-carbons were tested at 23°C. The materials obtained were activated bio-carbons of surface area ranging between 303 and 442 m2/g and showing basic character of the surface. The content of elemental carbon in the obtained samples was in the range of 73.4-82.1 wt. %. The maximum adsorption capacities of the materials towards nitrogen dioxide were 65 mg/g, methylene blue -207 mg/g, and iodine 1001 mg/g. According to the adsorption tests towards nitrogen dioxide, the sorption capacities of the adsorbents studied were increased if a mixture of nitrogen dioxide and air had a humidity of 70 %. The mechanism of methylene blue adsorption involved the formation of adsorptive multilayer. The most effective adsorbent of organic and inorganic pollutants proved to be the activated bio-carbon obtained from the residues after supercritical extraction of blackcurrants.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 6; 1357-1365
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of new carbon-nitrogen composites based on waste sweet drinks
Autorzy:
Kaźmierczak-Raźna, Justyna
Pietrzak, Robert
Nowicki, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/110875.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
carbon-nitrogen composites
waste sweet drinks
activated carbon
physical activation
physico-chemical properties
Opis:
The materials under investigation were new carbon-nitrogen composites obtained via pyrolysis and CO2 activation of sweet drinks destined for utilization. Waste Pepsi Cola® has been examined as an alternative and renewable carbon source for composite materials. Nitrogen was introduced into the Pepsi Cola® solution via the addition of guanidine carbonate, before the pyrolysis process. The physicochemical properties of the materials studied were characterized by low- temperature nitrogen adsorption (using BET and BJH methods), elemental analysis, FTIR spectroscopy, scanning electron microscopy (SEM) as well as determination of pHPZC and the number of surface functional groups. Additionally, thermal properties of the samples were investigated by thermogravimetric analysis (TG) and differential thermogravimetry (DTG). The final products were new carbon-nitrogen composites characterized by a very high content of nitrogen (11.2 - 21.6 wt.%) as well as relatively low surface area and pore volume reaching 198 m2/g and 0.16 cm3/g, respectively. Results of FT-IR study and Boehm titration indicated that the composites surface has clearly basic character, which was confirmed by pHpzc values above 8.0.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 6; 1366-1374
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Grzyby i odpady grzybowe jako nowe prekursory do otrzymywania adsorbentów węglowych
Mushroom and mushroom residues as new precursors for carbon adsorbents
Autorzy:
Koźlarek, Natalia
Bazan-Woźniak, Aleksandra
Pietrzak, Robert
Powiązania:
https://bibliotekanauki.pl/articles/2086743.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
biowęgiel
właściwości fizykochemiczne
fizyczna i chemiczna aktywacja
adsorpcja
biocarbon
physicochemical properties
physical and chemical activation
adsorption
Opis:
Undesirable changes in the bacteriological, physical and chemical properties of water are a consequence of introduction of excessive amounts of inorganic and organic materials to it. These pollutants limit or prevent the use of water for drinking, food production and household purposes. The greatest amounts of pollutants enter the watersystem with sewage. Also the pesticides,surfactants, organic dyes, artificial fertilizers along with municipal and industrial waste can easily enter water system and threaten the organisms living there. Another, equally important problem is the pollution of atmospheric air. Emission of solid liquid or gas pollutants to the atmosphere has been proved to have significant impact on human health, climate and nature. That is why the search for new and more effective technologies for the environment purification is a continuous challenge. Recently, increasingly often carbon materials are used as effective adsorbents of pollutants from liquid and gas phases.
Źródło:
Wiadomości Chemiczne; 2022, 76, 3-4; 221--236
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Membranes obtained on the basis of cellulose acetate and their use in removal of phenol from liquid phase
Autorzy:
Przybył, Joanna
Bazan-Wozniak, Aleksandra
Nosal-Wiercinska, Agnieszka
Pietrzak, Robert
Powiązania:
https://bibliotekanauki.pl/articles/2146950.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
cellulose acetate membrane
phase inversion
physical and chemical properties
surface
chemistry
phenol removal
Opis:
The membranes based on cellulose acetate (CA) were obtained by the method of phase inversion and used for removal of phenol (in concentrations of 15 and 25 mg/L) from liquid phase. To differentiate the hydrophilic properties of the membrane surfaces, different amounts of cellulose acetate (14 and 18 wt. %) and polyvinylpyrrolidone as a pore-generating agent (PVP, 1, 2, 3 or 4 wt. %) were used. The membranes were characterised by determination of their porosity, equilibrium water content, wetting angle and content of surface oxygen functional groups. After the application of membranes to phenol removal, the following parameters characterising the process were determined: permeability, membrane resistance, coke resistances, pore resistances, total filtration resistance and flux recovery ratio. The membranes were found to show higher effectiveness in phenol removal from a solution of the initial concentration 15 mg/L, and more effective were the membranes with higher contents of cellulose acetate. On the surface of the membranes the oxygen functional groups of acidic nature are dominant, both before and after filtration. The membranes of higher contents of cellulose acetate show higher resistances.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 2; art. no. 144174
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adsorption of 4-aminopyrimidine at the R-AgLAFE/chlorate(VII) interface. Comparison of the adsorption properties of various water activity as well as different surfactants
Autorzy:
Martyna, Marlena
Pawlak, Alicja
Grochowski, Mariusz
Bazan-Woźniak, Aleksandra
Pietrzak, Robert
Nosal-Wiercińska, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/24085664.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
4-aminopyrimidine
SDS
CTAB
R-AgLAFE
specific adsorption
Opis:
The results of 4-aminopyrimidine (4-APM) impact studies on the double layer parameters at the R-AgLAFE/ chlorates(VII) interface in the solutions with different water activity as well as different properties of the mixed adsorption layer of 4-aminopirimidine – sodium 1-decanesulfonate (SDS) and 4- aminopyrimidine - hexadecyltrimethylammonium bromide (CTAB) at the electrode/solution interface are discussed.The differential capacity of the double layer (Cd) at the R-AgLAFE/ basic solution interface was measured using the electrochemical impedance spectroscopy. The zero charge potential (Ez) was determined using a streaming electrode, while the surface tension at the zero charge potential (Yz) was measured using the largest pressure method inside the mercury drop. It was proved that both the 4-aminopirymidine concentration and water activity have an essential effect on the doublelayer parameters on the R-AgLAFE/ chlorates(VII) interface. In the studied systems: 4-APM - SDS and 4-APM - CTAB, 4-aminopyrimidine dominance was observed.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 4; art. no. 170204
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena warunków hydrogeologicznych w międzyrzeczu Kurówki i Bystrej (rejon Puław)
Evaluation of hydrogeological conditions between the Kurówka and Bystra Rivers (Puławy region)
Autorzy:
Zdechlik, Robert
Pietrzak, Paula
Powiązania:
https://bibliotekanauki.pl/articles/2061538.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
warunki hydrogeologiczne
chemizm wód podziemnych
międzyrzecze Kurówki i Bystrej
hydrogeological conditions
groundwater chemistry
interfluve of the Kurówka and Bystra rivers
Opis:
Badania przeprowadzono w celu oceny warunków hydrogeologicznych pierwszego poziomu wodonośnego w rejonie na wschód od Puław, na obszarze międzyrzecza Kurówki i Bystrej. W ujęciu regionalnym wody podziemne krążą w obrębie pozostających w łączności hydraulicznej pięter wodonośnych: czwartorzędowego, czwartorzędowo-kredowego i kredowego, przy czym dominującą rolę odgrywa piętro kredowe. Rzeki ograniczające obszar mają charakter drenujący i determinują układ pola hydrodynamicznego. Podstawą oceny warunków hydrogeologicznych były własne badania terenowe, obejmujące w 200 studniach pomiary głębokości do zwierciadła wody oraz oznaczenie właściwości fizykochemicznych wód, a z wytypowanych studni dodatkowo pobór próbek do szczegółowych badań laboratoryjnych. Oznaczone w wodach ze wszystkich studni wartości właściwości fizykochemicznych (pH, PEW i temperatury) zasadniczo mieszczą się w zakresie dopuszczalnym dla wód do spożycia. Wyniki szczegółowych oznaczeń laboratoryjnych makro- i mikroskładników w wodach podziemnych wskazują na przewagę słabego stanu chemicznego (6 punktów), w porównaniu do stanu dobrego (2 punkty). W odniesieniu do normatywów dla wód do spożycia, kryteria spełniają wody z 3 punktów, podczas gdy w 5 punktach wymogi nie są spełnione.
The research was carried out to assess the hydrogeological conditions of the first aquifer in the area between the Kurówka and Bystra rivers, east of Puławy. In regional terms, groundwater circulates within the hydraulically connected Quaternary, Quaternary- Cretaceous and Cretaceous aquifers, with the Cretaceous aquifer playing a dominant role. Rivers that limit the area are of a draining nature, determining the system of the hydrodynamic field. The assessment of hydrogeological conditions was carried out based on own field tests including the measurement of the depth to groundwater table and the determination of physicochemical properties in 200 wells, and collecting additional water samples for detailed laboratory tests from selected wells. The values of physicochemical properties (pH, PEW and temperature), determined in the water from all wells, are generally within an acceptable range of values for drinking water. The results of detailed research on chemical composition of groundwater indicate the dominance of the poor chemical status (6 points) over the good chemical status (2 points). Based on the norms that determine the quality of water for human consumption, only 3 out of 8 points meet the requirements.
Źródło:
Biuletyn Państwowego Instytutu Geologicznego; 2019, Hydrogeologia z. 16; 245--252
0867-6143
Pojawia się w:
Biuletyn Państwowego Instytutu Geologicznego
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bootstrap Method with Calibration for Standard Error Estimators of Income Poverty Measures
Autorzy:
Zięba-Pietrzak, Agnieszka
Kordos, Jan
Wieczorkowski, Robert
Powiązania:
https://bibliotekanauki.pl/articles/465812.pdf
Data publikacji:
2011
Wydawca:
Główny Urząd Statystyczny
Tematy:
Auxiliary information
Bootstrap
Calibration
Complex sample surveys
EU-SILC
Poverty indicators
Weighting
Opis:
The authors begin with calibration approach in sample surveys, focussing on the Eurostat approach. Next, the indicators of poverty and social exclusion are discussed as an essential tool for monitoring progress in the reduction of these problems. Most of these indicators are calculated according to the Eurostat recommendations, using data from European Statistics on Income and Living Conditions (EU-SILC). Complex sample design of the EU-SILC requires weighted analyses for estimates of population parameters and approximate methods of standard error estimation. In our study McCarthy and Snowden (1985) bootstrap method for standard errors estimation of income poverty measures is presented. In the next step the reweighting of bootstrap weights is applied and results of such calibration are discussed.
Źródło:
Statistics in Transition new series; 2011, 12, 1; 81-96
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of silver nanoparticles on metabolism and toxicity of moulds
Autorzy:
Pietrzak, Katarzyna
Twarużek, Magdalena
Czyżowska, Agata
Kosicki, Robert
Gutarowska, Beata
Powiązania:
https://bibliotekanauki.pl/articles/1038932.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
silver nanoparticles
moulds
mycotoxins
cytotoxicity
MTT
organic acids
extracellular enzymes
Opis:
The unique antimicrobial features of silver nanoparticles (AgNPs) are commonly applied in innumerable products. The lack of published studies on the mechanisms of AgNPs action on fungi resulted in identification of the aim of this study, which was: the determination of the influence of AgNPs on the mould cytotoxicity for swine kidney cells (MTT test) and the production of selected mycotoxins, organic acids, extracellular enzymes by moulds. The conducted study had shown that silver nanoparticles can change the metabolism and toxicity of moulds. AgNPs decrease the mycotoxin production of Aspergillus sp. (81-96%) and reduce mould cytotoxicity (50-75%). AgNPs influence the organic acid production of A. niger and P. chrysogenum by decreasing their concentration (especially of the oxalic and citric acid). Also, a change in the extracellular enzyme profile of A. niger and P. chrysogenum was observed, however, the total enzymatic activity was increased.
Źródło:
Acta Biochimica Polonica; 2015, 62, 4; 851-857
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interaction of three Caenorhabditis elegans isoforms of translation initiation factor eIF4E with mono- and trimethylated mRNA 5 cap analogues.
Autorzy:
Stachelska, Alicja
Wieczorek, Zbigniew
Ruszczyńska, Katarzyna
Stolarski, Ryszard
Pietrzak, Monika
Lamphear, Barry
Rhoads, Robert
Darżynkiewicz, Edward
Jankowska-Anyszka, Marzena
Powiązania:
https://bibliotekanauki.pl/articles/1043732.pdf
Data publikacji:
2002
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
fluorescence quenching
eIF4E
Caenorhabditis elegans
mRNA 5' cap
translation initiation
Opis:
Translation initiation factor eIF4E binds the m7G cap of eukaryotic mRNAs and mediates recruitment of mRNA to the ribosome during cap-dependent translation initiation. This event is the rate-limiting step of translation and a major target for translational control. In the nematode Caenorhabditis elegans, about 70% of genes express mRNAs with an unusual cap structure containing m32,2,7G, which is poorly recognized by mammalian eIF4E. C. elegans expresses five isoforms of eIF4E (IFE-1, IFE-2, etc.). Three of these (IFE-3, IFE-4 and IFE-5) were investigated by means of spectroscopy and structural modelling based on mouse eIF4E bound to m7GDP. Intrinsic fluorescence quenching of Trp residues in the IFEs by iodide ions indicated structural differences between the apo and m7G cap bound proteins. Fluorescence quenching by selected cap analogues showed that only IFE-5 forms specific complexes with both m7G- and m32,2,7G-containing caps (Kas 2×106 M-1 to 7×106 M-1) whereas IFE-3 and IFE-4 discriminated strongly in favor of m7G-containing caps. These spectroscopic results quantitatively confirm earlier qualitative data derived from affinity chromatography. The dependence of Kas on pH indicated optimal cap binding of IFE-3, IFE-4 and IFE-5 at pH 7.2, lower by 0.4 pH units than that of eIF4E from human erythrocytes. These results provide insight into the molecular mechanism of recognition of structurally different caps by the highly homologous IFEs.
Źródło:
Acta Biochimica Polonica; 2002, 49, 3; 671-682
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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