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1
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Carbonaceous Materials Obtained from Sewage Sludge for NO_2 Removal under Wet Conditions at Room Temperature

100%
Pietrzak R.
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issue 3
487-492
EN
The effect of the processes of carbonisation and activation on adsorbents obtained from sewage sludge and their sorption properties towards NO_2 were studied. Carbonaceous adsorbents were obtained by carbonisation of sewage sludge at 600°C for four different times 30, 60, 90 and 120 min followed by activation of the carbonisates by CO_2 at 800°C for 60 min. Adsorption of NO_2 was carried out in wet air. It has been shown that by appropriate thermal and chemical treatment of sludge, mesoporous adsorbents capable of NO_2 removal can be obtained. The sorption abilities of the carbonised and activated samples to adsorb NO_2 have been shown to increase with increased time of carbonisation and reach maximum for the carbonisation maintained for 90 min. Further increase in this time causes a decrease in the adsorption abilities of the samples. The sorption properties of the carbonisates have been proved to be determined by the chemical character of the surface, while those of the activated samples - by the porous structure.
2
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Positron Annihilation in Medical Substances of Insulin

64%
Pietrzak R., Szatanik R.
Acta Physica Polonica A
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2005
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vol. 107
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issue 5
852-856
EN
Positrons lifetimes were measured in medical substances of insulin (human and animal), differing as far as the degree of purity and time of their activity in the organism are concerned. In all of the cases the spectrum of positron lifetime was distributed into three components, with the long-life component ranging from 1.8 to 2.08 ns and the intensity taking on values from 18 to 24%. Making use of Tao-Eldrup model, the average radius of the free volume, in which o-Ps annihilated, and the degree of filling in the volume were determined. It was found that the value of the long-life component for human insulin is higher than that of animal insulin. Moreover, the value of this component clearly depends on the manner of purification of the insulin. It was also noticed that there occurs a correlation between the value of this component and the time after which it begins to be active in the organism, as well as the total time of its activity.
3
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The Influence of a Magnetic Field on the Formation of Corrosion Defects in Selected Metals and Steels, Analysed Using Positron Annihilation Method

64%
Pietrzak R., Szatanik R.
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vol. 125
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issue 3
733-736
EN
The method of positron lifetime measurement was used to analyse the influence of a magnetic field on the kinetics of corrosion defect formation in near-surface layers of iron, titanium as well as S20 and S0H18N9 steel grades. The listed metals, which belong to ferro- and paramagnetic materials, have different sensitivity to corrosion. It was found that not only the presence of a magnetic field, but also its direction influence the dimensions and the concentration of defects formed during corrosion.
4
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EPR Studies of Carbonized Cellulose - Oxygen Interactions

51%
Pilawa B., Pietrzak R., Wachowska H., Babeł K.
Acta Physica Polonica A
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2005
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vol. 108
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issue 1
151-154
EN
EPR examination of cellulose carbonized at 400ºC and 600ºC has been performed. The aim of this work was to search a sample useful as the oximetric probe in biology and medicine. The higher paramagnetic centers concentration characterizes cellulose carbonized at 600ºC, which was found as the sensitive oximetric probe. Quasi-chemical bonds between cellulose molecules and paramagnetic O_2 molecules decrease paramagnetic centers concentration. A linear increase in paramagnetic centers concentration and a linear decrease in EPR linewidth with increasing time of sample evacuation were observed for cellulose carbonized at 600ºC. Oxygen affects spin-lattice interactions in carbonized cellulose.
5
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The Effect of Ammoxidation Process on NO_2 Sorption Abilities of Active Carbons

51%
Nowicki P., Pietrzak R., Dobkiewicz M., Wachowska H.
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issue 3
493-499
EN
The paper presents results of a study on obtaining N-enriched active carbons from Polish brown coal and on their use as adsorbents for removal of pollution from gas phase. The crushed precursor was subjected to carbonisation at 500, 600 and 700°C in argon atmosphere. The chars obtained were activated by KOH at 800°C. The active carbons were further subjected to the ammoxidation at 350°C for 3 h, by a mixture of ammonia and air at the ratio of 1:3. The final products were microporous active carbons of well-developed surface area reaching to 2849 m^2/g and pore volume to 1.49 cm^3/g, showing mixed acid-base character of the surface. The results have shown that a suitable choice of the carbonisation, activation and ammoxidation procedures for brown coal can lead to obtaining activated carbons with high nitrogen dioxide adsorption ability, reaching from 16.9 to 36.4 mg NO_2/g.
6
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Investigations into the Influence of Hydrogen and Defects on the Spectra of Lifetime of Positrons in Palladium

51%
Pietrzak R., Szatanik R., Smiatek W.
Acta Physica Polonica A
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2001
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vol. 99
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issue 3-4
455-463
EN
The influence of interstitial hydrogen concentration and structural defects caused by quenching of palladium, begun at different temperatures up to the temperature of liquid nitrogen or by stretching by external forces, on spectra of lifetimes of positrons in this metal was investigated. It was found that the spectra of positron lifetimes in the examined systems are best described by their distribution into two components. On the basis of the two-state model of annihilation, the conclusion was drawn that the initial temperature from which quenching of palladium is commenced and also the relative elongation, which is caused by external forces, markedly influence the concentrations and sizes of defects in the sample.
7
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Multi-Component EPR Spectra of Coals with Different Carbon Content

51%
Pilawa B., Więckowski A., Pietrzak R., Wachowska H.
Acta Physica Polonica A
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2005
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vol. 108
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issue 2
403-407
EN
EPR spectra of lignite"Mequinenza" (Spain) (62.3 wt% C) and Polish orthocoking coal (87.8 wt% C) were compared. The spectra were superpositions of broad Gaussian, broad Lorentzian 1, and narrow Lorentzian 3 lines. Concentration of paramagnetic centers - mainly delocalizedπ electrons - responsible for narrow Lorentzian 3 lines increases with increase in carbon content in coal. Coal units with slow and fast spin-lattice relaxation processes exist in the two studied samples. Slow spin-lattice interactions occur in simple aromatic coal units with broad Gaussian and Lorentzian 1 lines. Fast spin-lattice relaxation processes are characteristic of large aromatic units with narrow Lorentzian 3 lines.
8
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Measurements of Positrons Lifetimes in Corroded Nickel

51%
Pietrzak R., Szatanik R., Szuszkiewicz M.
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vol. 95
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issue 4
647-651
EN
An attempt was undertaken at making use of a technique of taking measurements of lifetimes of positrons emitted from ^{22}Na source to investigate corroded nickel. It was found that after corrosion in HCl vapours mean positrons lifetime, the second component of positrons lifetimes as well as its intensity rise along with the corrosion time.
9
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The Influence of Filtration of Atrasine on the Spectrum of Positron Lifetimes in Immobilized Liquid Filtration Membranes

51%
Pietrzak R., Maksymiuk E., Kajdas A.
Acta Physica Polonica A
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2006
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vol. 110
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issue 5
649-658
EN
The spectra of positron lifetimes were investigated in elements which were later used to form an immobilized liquid membrane and also in the immobilized liquid membrane, after different times of atrasine filtration. Next, the spectra of positron lifetimes were separated out into three components. The values of the components of the positron lifetimes spectrum indicated the formation of the Ps-atom both in the elements composing the membrane and in the very membrane itself. An influence of the filtration time of atrasine on the values of all components of positron lifetimes spectrum was found. On the basis of Eldrup-Tao model, changes in the sizes of spherical free spaces in the membrane and relative free volume in which ortho-Ps annihilated were determined.
10
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Spectra of Positrons Lifetimes in Choose Gel Drugs

51%
Pietrzak R., Muszyńska J., Kajdas A.
Acta Physica Polonica A
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2006
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vol. 110
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issue 5
659-665
EN
Spectra of positrons lifetimes in selected gel non-steride analgesic and antiphlogistic drugs were investigated. The basic components in them were sodium salts of diclophenac and they differed from one another with the chemical composition of other components. It was found that in all of the investigated spectra there occurred a component which testified to the formation of positronium. The differences in the values of ortho-Ps component lifetimes and their intensity can be attributed to the presence of ingredients modifying the effects of the drug.
11
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The Influence of Magnetic Field on Annihilation of Positrons in Corroded Steel St-20

51%
Pietrzak R., Szatanik R., Jaworska A.
Acta Physica Polonica A
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2006
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vol. 110
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issue 5
677-681
EN
The positron lifetime in steel St-20 were determined before and following corrosion in HCl vapors. The influence of external magnetic field and remanent magnetization state on the parameters of the positron lifetime spectrum in the steel were investigated. It was found that the presence of magnetic field causes a decrease in the intensity of the component connected with annihilation of positrons in the close-to-the-surface lattice defects.
12
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Positron Annihilation in Corroded Steels St20 and St3S

51%
Pietrzak R., Smiatek W., Szatanik R.
Acta Physica Polonica A
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2006
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vol. 110
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issue 5
667-676
EN
The paper deals with examining the lifetimes of positrons emitted from ^{22}Na source in corroded St20 and St3S steels. Influence of the method of defecting the sample surfaces on the spectrum of positron lifetimes was investigated. Influence of temperature of initial annealing of samples, plastic deformation, electrolytic hydrogenation and corrosion in HCl vapors on trapping positrons in the examined steels was also determined.
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