Wyniki wyszukiwania - BazTech

1

Arsenate removal on the ion exchanger modified with cerium(III) ions

Dudek Sebastian, Kołodyńska Dorota

Physicochemical Problems of Mineral Processing

|

2022

|

Vol. 58, iss. 2

art. no. 147412

EN

The iron oxide ion exchanger Ferrix A33E was successfully modified with cerium(III) ions to obtain Ferrix A33E-Ce(III) providing much better sorption properties in relation to the As(V) species. The new material has been characterized using a number of techniques including scanning electron microscopy SEM, nitrogen adsorption/desorption isotherms, Fourier transform infrared spectroscopy FTIR and X-ray photoelectron spectroscopy XPS. At optimal pH 6 the main mechanism of arsenate adsorption on A33E-Ce(III) was electrostatic attraction and formation of monodentate and bidentate surface complexes. The process was exothermic and spontaneous. Unlike the unmodified ion exchanger, A33E-Ce(III) could completely remove arsenic from the arsenate solution at a concentration of 50 mg/dm3 in 60 minutes. Furthermore, the maximum sorption capacity for As(V) was determined to be 60.41 mg/g which almost doubled after modification with cerium(III) ions. It is also worth noting that even after three cycles of sorption/desorption A33E-Ce(III) exhibited a higher sorption capacity than unmodified A33E before the arsenate adsorption. It can be concluded that modifying the sorbent with a small amount of cerium(III) ions boosts its sorption properties significantly, improves effectiveness of water purification and reduces the overall operation cost

2

Comparison of Sensitivity of Autotrophic and Heterotrophic Microorganisms to the Pollution of Natural Water with Rare Earth Elements (Lanthanum and Cerium)

Lozhkina Roza A., Olkova Anna S., Koval Ekaterina V., Tomilina Irina I., Sysolyatina Maria A.

Journal of Ecological Engineering

|

2022

|

Vol. 23, nr 4

58--63

EN

The purpose of the work was to compare the sensitivity of autotrophic and heterotrophic organisms used in bioassay to lanthanum and cerium under the conditions of a model experiment with aqueous media. Using bioassay methods, the pre-lethal effects of La and Ce in heterotrophic Paramecium caudatum and Escherichia coli, as well as autotrophic Chlorella vulgaris and Nostoc linckia were determined. Model solutions of La2 (SO4)3∙8H2O and Ce2 (SO4)3∙8H2O were tested in the concentration range of 0.1–200 mg/l. As a result, it was shown that heterotrophic organisms are more sensitive to water pollution with La and Ce than autotrophic ones. According to the totality of experiments, cerium turned out to be more toxic than lanthanum. When planning the environmental studies of wastewater or reservoirs polluted with REE, it is recommended to focus on comparative sensitivity of bioassay methods, taking into account the test-functions used: bioassay for chemotaxis of P. caudatum > bioassay for changes in bioluminescence of E. coli (strain M-17) > bioassay for the content of chlorophyll а and intensity of lipid peroxidation in N. linckia > bioassay on the increase in the number of Cl. vulgaris.

3

Cerium-Promoted Nickel /Alumina Catalyst for Producer Gas Reforming and Tar Conversion

Aljbour Salah H., Kawamoto Katsuya

Journal of Ecological Engineering

|

2022

|

Vol. 23, nr 6

58--66

EN

The catalytic conversion of a model tar compound, namely: naphthalene contained in a simulated producer gas from wood gasification process was investigated. The sol-gel approach was used to create a mesoporous Cepromoted Ni/alumina catalyst with high surface area. A surface area of 333 m2g was achieved by calcination of the mesoporous catalyst (17 wt% Ni and 2.8 wt% Ce) under air conditions at 1123 K. The catalysts were characterized using the N2 adsorption-desorption, XRD, and SEM techniques, and their promotion effect on producer gas reforming and tar removal was studied under dry, steam, and partial oxidation conditions. The Ni-based catalysts effectively converted naphthalene and increased the proportion of H2 and CO in the reformed gas. Incorporating Ce into the catalyst increased the proportion of H2 and CO in the reformed gas, while lowering the amount of CH4 and CO2. In the absence of oxygen, catalytic reforming of the producer gas resulted in 79.6% naphthalene conversion, whereas catalytic partial oxidation conditions resulted in 99.1% naphthalene conversion.

4

Evaluation of alkali processing for the recycling of rare earth values from spent fluorescent lamps

Shukla Neha, Tanvar Himanshu, Dhawan Nikhil

Physicochemical Problems of Mineral Processing

|

2020

|

Vol. 56, iss. 4

710--722

EN

Phosphor samples collected after crushing and sieving of discarded fluorescent lamps comprise approximately 31 % rare earth elements in the form of Y1.90Eu0.10O3, Al11Ce0.67MgO19Tb0.33, and Al10.09Ba0.96Mg0.91O17: Eu2+ phase. Direct leaching and mechanical activation assisted leaching are incapable of recovering Ce, Tb values from the Al11Ce0.67MgO19Tb0.33 phase. Heat treatment with NaOH was found successful for dissociation of Ce, Tb phase via substitution of rare-earth ion by Na+ ion to form rare earth oxide and water-soluble NaAlO2. Y, Eu, Ce, and Tb values were recovered from heattreated mass in a two-step leaching process followed by recovery from the leach solution by oxalic acid precipitation. Over 95 % extraction rate was attained after heat treatment at 400 °C with 150 wt-% NaOH for 1 h. It was found that Y, Eu containing phase does not take part in the heat treatment process whereas the Ce, Tb phase undergoes a solid-state chemical reaction with NaOH via product layer diffusion model with 41.5 kJ/mol activation energy. Approximately 15 g mixed oxide (purity >95 %) of Y (79 %), Eu (7 %), Ce (5 %), and Tb (4 %) could be recovered from 100 units of discarded FLs. Microwave treatment of phosphor and NaOH (50 wt-%) yielded approximately 42 % Y, 100 % Eu, 65 % Ce, and 70 % Tb recovery in just 5 min. Approximately 9 g of REO and 5 g of cerium enriched leach residue were recovered from the microwave route within 5 min and depicted high microwave potential application in the recovery of Ce and Tb values from waste phosphor sample.

5

Nanoproszki na bazie TiO₂ do wytwarzania powłok samoczyszczących

Mańkowska Ewa, Kaczmarek Danuta, Obstarczyk Agata, Maciej Strzyżewski

Elektronika : konstrukcje, technologie, zastosowania

|

2019

|

Vol. 60, nr 7

24--26

PL

W pracy zaprezentowano wyniki badania wpływu ilości domieszki (2% at. oraz 4% at.) oraz temperatury wygrzewania (300°C i 600°C) na zdolność do rozkładu oranżu metylowego przez nanocząstki dwutlenku tytanu domieszkowane cerem (TiO₂:Ce) w wyniku procesu fotokatalizy. Nanocząstki TiO₂ zostały wytworzone metodą zol-żel, przy użyciu TTiP jako prekursora. Zaobserwowano, że lepsze właściwości fotokatalityczne ma próbka domieszkowana mniejszą ilością ceru, co oznacza, że istnieje optymalna zawartość domieszki. Aktywność fotokatalityczna tej próbki wynosiła 16,7%. Wygrzewanie w wysokiej temperaturze miało negatywny wpływ na zdolności próbek do rozkładu barwnika, gdyż aktywność fotokatalityczna żadnej z wygrzanych próbek nie przekroczyła 4%.

EN

This paper presents the results of the investigation of concentration of the dopant (2 at.% Ce and 4 at.% Ce) and high-temperature annealing (300°C i 600°C) on the decomposition of methyl orange by titanium dioxide nanoparticles doped with cerium (TiO₂:Ce) as a result of photocatalysis process. Methyl orange was decomposed by TiO₂:Ce nanoparticles, which were synthesized by sol-gel technique with using TTiP as a precursor. It was observed that the higher photocatalytic activity has been obtained by TiO₂ doped with smaller amount of cerium, which suggests the existence of the optimum dopant concentration. The photocatalytic activity of this nanoparticles was equal to 16.7%. Moreover, high-temperature annealing had a negative effect on TiO₂:Ce nanoparticles on decomposition ability, due to the fact that the photocatalytic activity of all annealed nanoparticles did not achieve 4%.

6

Szkła boranowe domieszkowane cerem aktywne optycznie w zakresie promieniowania wysokoenergetycznego

Świontek S., Adamczyk J., Środa M., Bilski P.

Materiały Ceramiczne

|

2018

|

T. 70, nr 2

116--121

PL

Pierwiastki ziem rzadkich jako domieszki optycznie aktywne w zakresie promieniowania wysokoenergetycznego znajdują coraz szersze zastosowania w układach wykazujących zjawiska termoluminescencji (TL) oraz optycznie stymulowanej luminescencji (OSL). Materiały takie są wykorzystywane do projektowania detektorów promieniowania jonizującego, mogących pracować nawet w przypadku najwyższych dawek. Obecnie wszystkie komercyjnie dostępne detektory TL i OSL są krystaliczne, podczas gdy szklane mogą stanowić obiecującą alternatywę. W pracy przeprowadzono pomiary termicznie i optycznie stymulowanej luminescencji w szkłach boranowych BaO-B2O3 domieszkowanych tlenkiem ceru. Stwierdzono, że wzrost zawartości domieszki w badanym materiale wpływa na zwiększenie wydajności procesu termoluminescencji i optycznie stymulowanej luminescencji.

EN

Rare earth elements are widely used as active dopants in the range of high-energy radiation in many systems which exhibit thermoluminescence (TL) and optically stimulated luminescence (OSL) phenomena. Such materials are used to design ionizing radiation detectors which can measure even the highest doses. It should be noted that all of the commercially available TL and OSL dosimeters are crystalline, while glassy ones could be a promising alternative. In this research thermally and optically stimulated luminescence measurements are carried out for BaO-B2O3 glasses doped with CeO2. It was found that the increase of cerium oxide dopant increases the efficiency of thermoluminescence and optically stimulated luminescence.

7

Oznaczanie ceru w kamieniach do zapalniczek metodą spektrofotometrii Uv-Vis

Kleszcz K., Mika M.

Tarnowskie Colloquia Naukowe. Nauki Techniczne i Ścisłe

|

2017

|

T. 4, nr 3

125--128

PL

W pracy opisano pomiar zawartości ceru w kamieniach do zapalniczek metodą spektrofotometryczną, która wykorzystuje tworzenie barwnego kompleksu ceru z formaldoksymem. W celu uzyskania wiarygodnych wyników, konieczne okazało się oddzielenie obecnego w próbkach żelaza. Dokonano tego wykorzystując metodę wytrącania szczawianu ceru.

EN

Determination of cerium in ferrocerium lighter flint stone by means of spectrophotometry is described. The method is based on the formation of cerium-formaldoxime complex. In order to achieve accurate results, it was necessary to separate iron which was present in the samples. It was achieved by precipitation of cerium oxalate.

8

Synthesis of Cu and Ce co-doped ZnO nanoparticles: crystallographic, optical, molecular, morphological and magnetic studies

Rawat M., Singh J., Singh J., Singh C., Singh A., Kukkar D., Kumar S.

Materials Science Poland

|

2017

|

Vol. 35, No. 2

427--434

EN

In the present research work, crystallographic, optical, molecular, morphological and magnetic properties of Zn1-xCuxO (ZnCu) and Zn1-x-yCeyCuxO (ZnCeCu) nanoparticles have been investigated. Polyvinyl alcohol (PVA) coated ZnCu and ZnCeCu nanoparticles have been synthesized by chemical sol-gel method and thoroughly studied using various characterization techniques. X-ray diffraction pattern indicates the wurtzite structure of the synthesized ZnCu and ZnCeCu particles. Transmission electron microscopy analysis shows that the synthesized ZnCu and ZnCeCu particles are of spherical shape, having average sizes of 27 nm and 23 nm, respectively. The incorporation of Cu and Ce in the ZnO lattice has been confirmed through Fourier transform infrared spectroscopy. Room temperature photoluminescence spectra of the ZnO doped with Cu and co-doped Ce display two emission bands, predominant ultra-violet near-band edge emission at 409.9 nm (3 eV) and a weak green-yellow emission at 432.65 nm (2.27 eV). Room temperature magnetic study confirms the diamagnetic behavior of ZnCu and ferromagnetic behavior of ZnCeCu.

9

Catalytic activity of cobalt and cerium catalysts supported on calcium hydroxyapatite in ethanol steam reforming

Dobosz J., Hull S., Zawadzki M.

Polish Journal of Chemical Technology

|

2016

|

Vol. 18, nr 3

59--67

EN

In this paper, Co,Ce/Ca10(PO4)6(OH)2 catalysts with various cobalt loadings for steam reforming of ethanol (SRE) were prepared by microwave-assisted hydrothermal and sol-gel methods, and characterized by XRD, TEM, TPR-H2, N2 adsorption-desorption measurements and cyclohexanol (CHOL) decomposition tests. High ethanol conversion (close to 100%) was obtained for the catalysts prepared by both methods but these ones prepared under hydrothermal conditions (HAp-H) ensured higher hydrogen yield (3.49 mol H2/mol C2H5OH) as well as higher amount of hydrogen formed (up to 70%) under reaction conditions. The superior performance of 5Co,10Ce/HAp-H catalyst is thought to be due to a combination of factors, including increased reducibility and oxygen mobility, higher density of basic sites on its surface, and improved textural properties. The results also show a significant effect of cobalt loading on catalysts efficiency in hydrogen production: the higher H2 yield exhibit catalysts with lower cobalt content, regardless of the used synthesis method.

10

Effect of cerium on structural and optical properties of ZnO aerogel synthesized in supercritical methanol

Meddouri M., Hammiche L., Slimi O., Djouadi D., Chelouche A.

Materials Science Poland

|

2016

|

Vol. 34, No. 3

659--664

EN

Pure ZnO and Ce-doped (5 at.%) ZnO aerogels were prepared by dissociation of dihydrate zinc acetate and cerium nitrate in methanol, followed by drying in supercritical conditions of the solvent. The concentration of zinc acetate solution and the atomic ratio Ce/Zn were fixed at 0.2 mol/L and 0.05 mol/L, respectively. XRD results showed a hexagonal wurtzite structure of ZnO aerogel crystallites and a formation of a separate second phase of ceria cubic phase with fluorite structure and 7.4 nm in size. The introduction of cerium in the solution had a negative effect on the aerogel crystalline quality. The crystallites size was found to be 16 nm in pure ZnO and 27 nm in Ce-doped ZnO aerogels. The grains of Ce-doped ZnO aerogel had torus shaped morphology with hollow centers, but those of pure ZnO were flattened semispheres. The calculated values of different structural parameters showed that cerium ions introduced into the ZnO lattice occupied interstitial sites and Zn ions substituted Ce ones in ceria lattice during the formation process. FT-IR and UV-Vis absorption spectra have not revealed any particularities due to the presence of cerium atoms in ZnO, indicating that Ce (5 at.%) doping of ZnO crystallites synthesized in supercritical methanol did not strongly affect the optical gap of the semiconductor. Micro-Raman studies confirmed the formation of cubic fluorite structure ceria in ZnO aerogel and showed that Raman active modes of ZnO are amplified with the presence of ceria.

11

Bioactive black glasses and their modification with cerium

Gawęda M., Długoń E., Sitarz M.

Engineering of Biomaterials

|

2016

|

Vol. 19, no. 138 spec. iss.

122

12

Influence of Rare Earth Metals on Microstructure and Inclusions Morphology G17CrMo5-5 Cast Steel

Kasińska J.

Archives of Metallurgy and Materials

|

2014

|

Vol. 59, iss. 3

993--996

EN

This paper presents influence of rare earth metals (REM) on the microstructure and morphology of non-metallic inclusions of G17CrMo5-5 cast carbon steel The research has been performed on successive industrial melts. Each time about 2000 kg of liquid metal was modified. The REM was in the form of mishmetal of the composition 49,8% Ce, 21, 8% La, 17, 1% Nd, 5, 5% Pr and 5, 35% the rest of REM. Therareearth metals were put into the ladle during tapping of heat melt from the furnace.

PL

W artykule przedstawiono rolę metali ziem rzadkich na strukturę I morfologię wtrąceń niemetalowych w staliwie węglowym G17CrMo5-5. Badania prowadzono na seryjnych wytopach przemysłowych. Każdorazowo modyfikacji poddawano po około 2000kg ciekłego metalu. Metale ziem rzadkich wprowadzano w postaci miszmetalu o składzie: 49, 8% Ce, 21, 8% La, 17, 1% Nd, 5, 5% Pr and 5, 35%. Metale ziem rzadkich wprowadzano do kadzi podczas spustu ciekłego metalu z pieca.

13

Opracowanie nowoczesnego efektywnego katalizatora do produkcji wodoru zasilającego ogniwa paliwowe

Madej-Lachowska M.

Przemysł Chemiczny

|

2012

|

T. 91, nr 11

2245--2247

PL

Przebadano wpływ ceru oraz chromu na aktywność katalizatorów Cu/Zn/Zr oraz Cu/Zn/Zr/Ga do procesu reformingu metanolu parą wodną w aspekcie otrzymywania wodoru do zasilania ogniw paliwowych. Stwierdzono znaczną poprawę właściwości katalitycznych w przypadku katalizatorów Cu/Zn/Zr modyfikowanych chromem oraz chromem i cerem.

EN

Cr and/or Ce were added as dopants to Cu-Zn-Zr and Cu-Zn-Zr-Ga oxide catalysts used for steam reforming of MeOH. The Cr and Cr-Cu-doped catalysts showed an increasing activity even at low temp. (433–473 K).

14

Lantan i cer w glebach Polski

Kwecko P.

Przegląd Geologiczny

|

2012

|

Vol. 60, nr 9

490–-495

EN

The paper present basic spatial analysis lanthanum and cerium distribution in Poland soils. Attempted to determine geochemical background and range and intensity of enrichment and anomalies La and Ce content in top (0–0,2 m) and bottom (0,5–2 m) soils. These data are presented in the form two color maps of polygonal with basic statistic information. The text part describes the main areas of enrichment and attempts to indicate the source of these values.

15

Wpływ ceru lub lantanu na aktywność niklowych katalizatorów metanizacji tlenków węgla

Gołębiowski A., Stołecki K., Michalska K., Narowski R., Borowiecki T.

Przemysł Chemiczny

|

2011

|

T. 90, nr 12

2145-2147

16

Derivative thermo analysis of the Al-Si cast alloy with addition of rare earths metals

Krupiński M., Labisz K., Dobrzański L. A., Rdzawski Z.

Archives of Foundry Engineering

|

2010

|

Vol. 10, iss. 1

79-82

EN

In this paper the dependence between chemical composition, structure and cooling rate of Al-Si aluminium cast alloy was investigated. For studying of the structure changes the thermo-analysis was carried out, using the UMSA (Universal Metallurgical Simulator and Analyzer) device. For structure investigation optical and electron scanning microscopy was used, phase and chemical composition of the Al cast alloy also using qualitative point-wise EDS microanalysis.

17

Fabrication of mesoporous mixed oxides containing copper and cerium by using substituted anionic clays as precursors

Carja G., Dranca S., Ciobanu G., Husanu E., Balasanian I.

Materials Science Poland

|

2009

|

Vol. 27, No. 3

909--917

EN

Copper and cerium partially substituted anionic clay was synthesized by the coprecipitation method. The XRD analysis and N2 adsorption at 77 K indicated that calcination destroys the layered matrix of the clay, giving rise to mixed oxides having a high surface area and mesoporous characteristics; SEM analysis showed that the new formed mixed oxides consist of ensembles of highly agglomerated, interconnected nanoparticles. It results from XPS that copper and cerium both contribute to establish the specific redox properties on the surface.

18

Microstructure and mechanical properties of the Al-Ti alloy with cerium addition

Dobrzański L. A., Labisz K., Maniara R., Olsen A.

Journal of Achievements in Materials and Manufacturing Engineering

|

2009

|

Vol. 37, nr 2

622-629

EN

Purpose: In this work there are presented the investigation results of mechanical properties and microstructure concerning mainly intermetallic phases of the aluminium – titanium alloy with a defined content of 2 and 4 % of cerium addition. The purpose of this work was also to determine the heat treatment conditions for solution heat treatment of the investigation alloys. Design/methodology/approach: The reason of this work was to determine the heat treatment influence, particularly solution heat treatment time to the changes of the microstructure, as well to determine which intermetallic phases occur after the heat treatment performed, and how is the morphology of these particles. Findings: After solution heat treatment for 4 hours the structure changes. The grains are larger and no more uniform as showed before. The most stable intermetallic in the Al-Ti system is the Al3Ti phase. The solution heat treatment time should be greater than 4 hours to ensure a proper solution of titanium and cerium in the Al-á solid solution. Research limitations/implications: The investigated aluminium samples were examined metallographically using optical microscope with different image techniques, scanning electron microscope and also analyzed using a Vickers micro-hardness tester, also EDS microanalysis was made. Practical implications: As an implication for the practice a new alloy can be developed, some other investigation should be performed in the future, but the knowledge found in this research shows an interesting investigation direction. Originality/value: The combination of light weight and high strength Ti-based alloys is very attractive for aerospace and automotive industries. Furthermore, the presence of calcium cerium into existence new unknown phases as well can enhance the thermal stability of ternary Al-Ti-Ce alloy because of its higher melting point then Al-Ti.

19

Bioszkła żelowe z dodatkiem srebra i ceru

Cholewa-Kowalska K.

Materiały Ceramiczne

|

2008

|

R. 60, nr 2

81-84

PL

Celem pracy było uzyskanie metodą zol-żel bioaktywych szkieł z układu SiO2 - CaO - P2O5 z dodatkiem Ag2O (0,5-3%mol.) oraz CeO2 (0,5-2%mol.). Ze względu na zawartość głównych składników materiały podzielono na serie: SAg, SCe - materiały wysokokrzemianowe (koncentracja SiO2 80% mol.) z dodatkiem odpowiednio Ag2O lub CeO2, AAg, ACe - materiały wysokowapniowe (koncentracja CaO 54 %mol.) Otrzymane w formie granulek szkła scharakteryzowano pod względem strukturalnym oraz określono ich zdolność do krystalizacji. Właściwości bioaktywne oceniano w odniesieniu do formowania się powierzchniowej warstwy HAp na badanych materiałach podczas kontaktu z symulowanym osoczem (SBF).

EN

The purpose of these studies was to obtain gel-derived bioglasses from the CaO-SiO2-P2O5 system with additions of Ag2O (0,5%-3mol) or CeO2 (0,5-2%mol) by the sol-gel method. Due to different chemical compositions the materials were designated as: SAg, SCe - high silica glass (SiO2 concentration - 80%mol,) and AAg, ACe2 - high lime material (CaO concentration - 54%mol.) with additions of silver or cerium respectively. The biomaterials prepared in the form of granules were characterised with respect to phase composition and ability to crystallization. Preliminary examination of bioactivity comprising behavior of granules in simulated body fluid SBF were carried out.

20

A new spectrofluorimetric method for determination of nifedipine in pharmaceutical formulations

Tabrizi A. B.

Chemia Analityczna

|

2007

|

Vol. 52, No. 4

635-643

EN

A new, simple, sensitive, and fast spectrofluorimetric method for determination of nifedipine in pharmaceutical formulations has been presented. In the proposed procedure nifedipine was oxidized with Ce(IV) and the fluorescence of the produced Ce(III) was measured at 354 nm after excitation at 255 nm. The factors influencing oxidation of the drug were studied and optimized. Under the applied experimental conditions, the calibration plots were linear over nifedipine concentration range 0.05-2.0 mg L-1 The limit of detection was 0.015 mgL-1 and the relative standard deviation for 5 replicate determinations of nifedipine at 1.0 mg L-1 concentration level was 1.53%. Good recoveries in the range 95-104% were obtained in spiked samples. The proposed method was successfully applied to the determination of nifedipine in pharmaceutical formulations.

PL

Przedstawiono nową, czułą, prostą i szybką spektra fluory metryczną metodę oznaczania nifedypiny w preparatach farmaceutycznych. Metoda postępowania polega na utlenieniu nifedypiny za pomocą Ce(IV) a fluorescencja powstającego Cc(III) jest mierzona przy długości fali 354 nm (po wzbudzeniu za pomocą promieniowania o ). = 255 nm). Zbadano i zoptymalizowano czynniki wpływające na utlenianie leku. W ustalonych warunkach doświadczalnych krzywa kalibracyjna była liniowa w zakresie stężeń nifedypiny 0:05-2,0 mg L-1, Granica wykrywalności wynosiła 0,015 mg L-1 a względne odchylenie standardowe wyznaczone na poziomie stężeń nifedypiny 1,0 mg L-1 na podstawie 5-u równo ległych oznaczeń wynosiło 1,53%. Odzysk dla próbek z dodatkiem ieku był w granicach 95-104%. Metodę zastosowano z powodzeniem do oznaczania nifedypiny w preparatach farmaceutycznych.