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Tytuł:
EPR spectroscopy of Cu2+ and Mn2+ in borate glasses
Autorzy:
Drzewiecki, A.
Padlyak, B.
Adamiv, V.
Burak, Y.
Teslyuk, I.
Powiązania:
https://bibliotekanauki.pl/articles/147654.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
borate glasses
Cu2+ paramagnetic centre
electron paramagnetic resonance (EPR) spectroscopy
hyperfine structure
Mn2+ paramagnetic centre
Opis:
Electron paramagnetic resonance (EPR) spectra of the CaB4O7 and LiCaBO3 glasses containing 0.5 and 1.0 mol.% CuO and MnO2 impurity compounds were investigated at room temperature. The glasses with CaB4O7:Cu, LiCaBO3:Cu, CaB4O7:Mn and LiCaBO3:Mn compositions were produced from the corresponding polycrystalline compounds using standard glass synthesis and technological conditions developed by the authors. The EPR spectral parameters of the Cu2+ and Mn2+ centres in both glasses containing 0.5 and 1.0 mol.% CuO and MnO2 doping oxides were determined. Analysis of EPR spectral parameters shows that Cu impurity is incorporated into the CaB4O7 and LiCaBO3 glass network as isolated Cu2+ (3d9, 2D5/2) paramagnetic ions. The Cu2+ ions occupy Ca(Li) sites of the borate glass network coordinated by six O2− anions with geometry of elongated octahedron (D4h symmetry) due to the Jahn- -Teller effect. The EPR spectra of the Mn-doped CaB4O7 and LiCaBO3 glasses are virtually identical and typical of all oxide glasses activated with Mn2+ (3d5, 6S5/2) ions. Observed EPR spectra in the Mn-doped glasses were attributed to isolated Mn2+ (1) centres (geff ≅ 4.3) in octahedral Ca(Li) sites with a strong (fully) rhombic distortion, isolated Mn2+ (2) centres (geff ≅ 2.0) in octahedral Ca(Li) sites with nearly cubic local symmetry as well as pairs and small clusters of the Mn2+ ions, coupled by magnetic dipolar and exchange interactions. On the basis of the obtained results and analysis of referenced data, the local structure of the Cu2+ and Mn2+ centres in the borate glasses have been proposed.
Źródło:
Nukleonika; 2013, 58, 3; 379-385
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carnot heat engine efficiency with a paramagnetic gas
Autorzy:
Malaver, Manuel
Powiązania:
https://bibliotekanauki.pl/articles/1066270.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Carnot heat engine
external magnetic field
ideal paramagnetic gas
ideal paramagnetic medium
magnetic moment
thermal efficiency
Opis:
The ideal gas approach is very useful in the study of behavior of the compressible fluids because it considers that the gas is composed of many randomly point particles and the interactions between them are perfectly elastic. The ideal gas concept is very important in the analysis of thermodynamic systems and in statistical mechanics. A system that can be studied with this approximation is the ideal paramagnetic gas, which consists of molecules where each of them possesses a magnetic moment in the presence of an external magnetic field. In this paper, we extended the work of Malaver (2015, 2018) for a variable Chaplygin gas to a paramagnetic medium and we have obtained some equations that describe thermodynamic behavior in an ideal paramagnetic gas. It has been derived an expression for the thermal efficiency of Carnot heat engine with a paramagnetic gas as working substance. We found that the efficiency depends on the limits of maximum and minimal temperature imposed on the Carnot cycle, as in the ideal gas, photon gas and variable Chaplygin gas.
Źródło:
World Scientific News; 2019, 130; 116-126
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparatwe EPR analysis of oxygen interactions with plants carbonized at different temperatures
Autorzy:
Bartłomiejczyk, S.
Pilawa, B.
Krzesińska, M.
Pusz, S.
Zachariasz, J.
Wałach, W.
Powiązania:
https://bibliotekanauki.pl/articles/284848.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
karbonizacja roślin
centra paramagnetyczne
paramagnetyczne utlenianie cząsteczek
elektroniczny rezonans paramagnetyczny
widma EPR
oksymetria
carbonized plants
paramagnetic centers
paramagnetic oxygen molecules
electron paramagnetic resonance
EPR spectra
oximetry
Opis:
Carbon materials, bamboo (Bambusa vulagris) and yucca (Yucca flaccida) pyrolysed at 550°C, 750°C and 950°C, were tested as oximetric probes by electron paramagnetic resonance spectroscopy at X-band (9.3 GHz). The following parameters of the spectra: amplitude, linewidth and g-factor, were determined. Influence of oxygen molecules 02 on EPR spectra of the individual carbon materials was compared. Strong EPR spectra were recorded for samples carbonized at 550°C and weak signals were obtained for plants carbonized at higher temperatures: 750°C and 950°C. It was stated that amplitudes of EPR lines of all the carbonized plants decrease in the air environment compared to amplitudes of spectra measured in vacuum. This effect increases with degree of vacuum. Changes in the EPR spectra of samples studied in the air environment may be applied in medicine to determination of oxygen content in different cells. Because of strong resonance signals as oximetric probes we proposed bamboo and yucca carbonized at 550°C, and we rejected plants carbonized at 750°C and 950°C with Iow EPR signals.
Źródło:
Engineering of Biomaterials; 2008, 11, 73; 3-5
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on irradiated D-mannose isolated from cranberry
Autorzy:
Guzik, Grzegorz P.
Stachowicz, Wacław
Michalik, Jacek
Powiązania:
https://bibliotekanauki.pl/articles/147508.pdf
Data publikacji:
2019
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
crystallite
electron paramagnetic resonance
EPR
irradiation
mannose
Opis:
The stable EPR signal produced by ionizing radiation in crystalline D-mannose (C6H12O6) and separated from cranberries (Vaccinium oxycoccus) was studied. The isothermal heating of irradiated sample at 95°C for 10 minutes (melting point of D-mannose is 132°C) resulted in the modifi cation and simplifi cation of the EPR signal involved. The isotropic quartet has been recognized in the EPR signal of heat-treated sample. Molecular structure of the isotropic quartet identifi ed in the complex EPR signal of D-mannose crystallite is proposed.
Źródło:
Nukleonika; 2019, 64, 4; 139-143
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Alanine dosimetry of 60 MeV proton beam - preliminary results
Autorzy:
Michalec, B.
Mierzwińska, G.
Sowa, U.
Ptaszkiewicz, M.
Nowak, T.
Swakoń, J.
Powiązania:
https://bibliotekanauki.pl/articles/146730.pdf
Data publikacji:
2012
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
alanine
dosimetry
electron paramagnetic resonance (EPR)
proton beam
Opis:
Electron paramagnetic resonance (EPR) spectrometry (X-band) was used to determine the dose absorbed in alanine detectors, of different shapes and different alanine content, irradiated with Co-60 gamma rays and in a 60 MeV proton beam. The goal of our study was to confirm applicability of alanine as a passive detector in therapeutic proton beam. In the paper dose response characteristic and relative efficiency of alanine are shown. The study confirmed that alanine detectors with a high alanine content (ca. 95%) may be a useful and convenient tool for dose measurements in proton beams, used for eye cancer treatment.
Źródło:
Nukleonika; 2012, 57, 4; 503-506
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wytwarzanie niskich temperatur metodą chłodzenia magnetycznego
Generation of low temperatures by the magnetic cooling method
Autorzy:
Kotynia, K.
Powiązania:
https://bibliotekanauki.pl/articles/134686.pdf
Data publikacji:
2015
Wydawca:
ADVSEO
Tematy:
chłodzenie magnetyczne
sól paramagnetyczna
magnetic refrigeration
paramagnetic salts
Opis:
The discussed process of lowering temperature (below 1 K) concerns the utilization of the magnetic properties of paramagnetic materials. The most important achievements and the progress in the field of low temperatures have been presented. The use of the effect of adiabatic paramagnetic material demagnetization known for over a hundred years has brought about numerous evident benefits. Although the magnetic cooling process is still not commonly used it is applied, for example, as an auxiliary way of attaining low temperatures of around 0 K, but its application is not common. This is due to the fact that the scientists are still searching for an appropriate material which would provide the capability to reduce the temperature to a sufficiently low level. So far, paramagnetic salts and alums, among others, have been used in the adiabatic demagnetization process, but the efficiency of those compounds is too low as against the needs.
Źródło:
Technical Issues; 2015, 2; 24-31
2392-3954
Pojawia się w:
Technical Issues
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mitochondria recycle nitrite back to the bioregulator nitric monoxide.
Autorzy:
Nohl, Hans
Staniek, Katrin
Sobhian, Babak
Bahrami, Soheyl
Redl, Heinz
Kozlov, Andrey
Powiązania:
https://bibliotekanauki.pl/articles/1044210.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
nitrite reductase
electron paramagnetic resonance
nitric oxide
mitochondria
Opis:
Nitric monoxide (NO) exerts a great variety of physiological functions. L-Arginine supplies amino groups which are transformed to NO in various NO-synthase-active isoenzyme complexes. NO-synthesis is stimulated under various conditions increasing the tissue of stable NO-metabolites. The major oxidation product found is nitrite. Elevated nitrite levels were reported to exist in a variety of diseases including HIV, reperfusion injury and hypovolemic shock. Denitrifying bacteria such as Paracoccus denitrificans have a membrane bound set of cytochromes (cyt cd1, cyt bc) which were shown to be involved in nitrite reduction activities. Mammalian mitochondria have similar cytochromes which form part of the respiratory chain. Like in bacteria quinols are used as reductants of these types of cytochromes. The observation of one-e- divergence from this redox-couple to external dioxygen made us to study whether this site of the respiratory chain may also recycle nitrite back to its bioactive form NO. Thus, the aim of the present study was therefore to confirm the existence of a reductive pathway which reestablishes the existence of the bioregulator NO from its main metabolite NO2-. Our results show that respiring mitochondria readily reduce added nitrite to NO which was made visible by nitrosylation of deoxyhemoglobin. The adduct gives characteristic triplet-ESR-signals. Using inhibitors of the respiratory chain for chemical sequestration of respiratory segments we were able to identify the site where nitrite is reduced. The results confirm the ubiquinone/cyt bc1 couple as the reductant site where nitrite is recycled. The high affinity of NO to the heme-iron of cytochrome oxidase will result in an impairment of mitochondrial energy-production. "Nitrite tolerance" of angina pectoris patients using NO-donors may be explained in that way.
Źródło:
Acta Biochimica Polonica; 2000, 47, 4; 913-921
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie korelacji właściwości elektrycznych i magnetycznych wybranych materiałów paramagnetycznych
Checking of the correlation of electrical and magnetic properties of selected paramagnetic materials
Autorzy:
Piaskowy, A.
Skórkowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/156750.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
paramagnetyki
przenikalność magnetyczna
konduktywność
paramagnetic
magnetic permeability
conductivity
Opis:
W artykule przedstawiono wyniki badań właściwości elektrycznych oraz magnetycznych materiałów charakteryzujących się niewielką podatnością magnetyczną. Opisano układy oraz metody pomiaru zarówno przenikalności magnetycznej jak również konduktywności takich materiałów. W podsumowaniu zawarto wnioski wyciągnięte z badania korelacji właściwości elektrycznych i magnetycznych.
The characteristic feature of paramagnetic materials is very small value of the magnetic permeability, very close to unity, so a reliable measurement is not a typical issue. Measurement circuit, presented in the article, allows measure both active and reactive components of the induced voltage in the winding of the detection coil, wherein the sample material is placed. The measurement procedure is two-step, first the reactive component of induced voltage is measured at the terminals of the detection coil with the sample, and second without the sample, and based on the determined values the permeability is calculated. The article presents results of several samples of selected paramagnetic materials. Studies include both permeability and conductivity of those materials. Attempted to correlate occurred magnetic permeability of tested material with its conductivity. The summary contains conclusions based on tested properties. Further research will involve an correlation attempt of the active component of the voltage induced in the detection coil of the present measuring system (Fig. 1) with the electrical properties of the sample.
Źródło:
Pomiary Automatyka Kontrola; 2014, R. 60, nr 11, 11; 1010-1012
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on radiation-induced radicals giving rise to stable EPR signal suitable for the detection of irradiation in L-sorbose-containing fruits
Autorzy:
Guzik, G. P.
Stachowicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/146498.pdf
Data publikacji:
2016
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
sorbose
crystallite
electron paramagnetic resonance (EPR)
EPR
irradiation
Opis:
The stable and complex EPR signals produced by the action of ionizing radiation on crystalline L-sorbose (C6H12O6) separated from rowan berries (Sorbus aucuparia) were studied. Isothermal heating of the samples at the temperature close to the melting point of L-sorbose (140°C) results in the modification and simplification of the EPR signal involved. In the EPR signal of heated L-sorbose, the isotropic quartet was distinguished. In the differential spectrum obtained by subtraction of normalized spectra of unheated and heated L-sorbose, the isotropic doublet was identified in addition. The DFT fitting offers the probable assignment of the EPR signals to specifi c radical structures.
Źródło:
Nukleonika; 2016, 61, 4; 461-465
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of microwave power on EPR spectra of natural and synthetic dental biocompatible materials
Autorzy:
Adamczyk, J.
Ramos, P.
Pilawa, B.
Powiązania:
https://bibliotekanauki.pl/articles/147235.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
EPR
microwave saturation
paramagnetic centers
dental biocompatible materials
Opis:
Paramagnetic centers in the two exemplary synthetic and natural dental biocompatible materials applied in implantology were examined by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra were measured in the range of microwave power 2.2–70 mW. The aims of this work were to compare paramagnetic centers concentrations in different dental biocompatible materials and to determine the effect of microwave power on parameters of their EPR spectra. It is the very fi rst and innovatory examination of paramagnetic centers in these materials. It was pointed out that paramagnetic centers existed in both natural (~1018 spin/g) and synthetic (~1019 spin/g) dental biocompatible materials, but the lower free radical concentration characterized the natural sample. Continuous microwave saturation of EPR spectra indicated that faster spin-lattice relaxation processes existed in synthetic dental biocompatible materials than in natural material. Linewidths (ΔBpp) of the EPR spectra of the natural dental material slightly increased for the higher microwave powers. Such effect was not observed for the synthetic material. The broad EPR lines (ΔBpp): 2.4 mT, 3.9 mT, were measured for the natural and synthetic dental materials, respectively. Probably strong dipolar interactions between paramagnetic centers in the studied samples may be responsible for their line broadening. EPR spectroscopy is the useful experimental method in the examination of paramagnetic centers in dental biocompatible materials.
Źródło:
Nukleonika; 2015, 60, No. 3, part 1; 449-453
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of oxygen O2 on microwave saturation of EPR lines of plants carbonized at 650°c and potential application in medicine
Autorzy:
Pilawa, B.
Bartłomiejczyk, S.
Krzesińska, M.
Pusz, S.
Zachariasz, J.
Wałach, W.
Powiązania:
https://bibliotekanauki.pl/articles/284844.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
karbonizacja roślin
elektroniczny rezonans paramagnetyczny
EPR
nasycenie mikrofalowe
centra paramagnetyczne
oksymetria
carbonized plants
electron paramagnetic resonance
microwave saturation
paramagnetic centers
oximetry
Opis:
Electron paramagnetic resonance spectroscopy (EPR) was used to examination of spin-lattice relaxation in vascular plants carbonized at 650°C. Application of EPR method of continuous microwave signal saturation in medicine was proposed. The first derivative EPR spectra of pyrolysed bamboo and yucca were measured for samples in air and in vacuum. Influence of microwave power in the range 0.7-100 mW on amplitudes of EPR lines were evaluated. It was stated that amplitudes of the studied carbon materials increase with increasing of microwave power in the studied range. Saturation of EPR lines was not observed, so fast spin-lattice relaxation processes exist in the analyzed materials. Changes of EPR amplitudes for samples in air were slower than for evacuated samples. This effect may be used for determination of oxygen contents in the biological cells cultures and for analysis of optimal parameters of photodynamic therapy of cancer.
Źródło:
Engineering of Biomaterials; 2008, 11, 73; 9-11
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the fraction of paramagnetic centers not-fulfilling the Curie law in coal macerals by the two-temperature EPR measurement method
Autorzy:
Słowik, G. P.
Więckowski, A. B.
Powiązania:
https://bibliotekanauki.pl/articles/146892.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
electron paramagnetic resonance (EPR)
macerals
two-temperature EPR measurement
Opis:
Two-temperature electron paramagnetic resonance (EPR) measurements, applied to determine the relative contributions of paramagnetic centers – fulfilling and not-fulfilling the Curie law, were carried out. The measurements were made on the macerals – exinite and vitrinite, separated from clarain of the Polish medium- -rank coal (85.6 wt% C). The two-temperature EPR measurements, presented in this work, were performed respectively, at temperatures: T1 = 293 K and T2 = 173 K for exinite, and T1 = 293 K and T2 = 153 K for vitrinite. The relative contributions X of spins not-fulfilling the Curie law present in the studied macerals were calculated. A comparison of different methods of calculating the relative contributions of paramagnetic centers – fulfilling and not-fulfilling the Curie law, present in exinite and vitrinite studied by EPR was made.
Źródło:
Nukleonika; 2015, 60, No. 3, part 1; 389-393
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of irradiated dried fruits using EPR spectroscopy
Autorzy:
Guzik, G. P.
Stachowicz, W.
Michalik, J.
Powiązania:
https://bibliotekanauki.pl/articles/148844.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
dried fruits
electron paramagnetic resonance (EPR)
fructose
glucose
irradiation
Opis:
The dominating carbohydrates in fruits are monosaccharides like fructose, glucose, sorbose and mannose. In dehydrated fruits, concentration of monosaccharides is higher than in fresh fruits resulting in the formation of sugar crystallites. In most of dried fruits, crystalline fructose, and glucose dominate and appear in proportion near to 1:1. Irradiation of dried fruits stimulates radiation chemical processes resulting in the formation of new chemical products and free radicals giving rise to multicomponent EPR signal which can be detected for a long period of time. For that reason, it is used as a marker for the detection of radiation treatment of dried fruits. It has been found that EPR spectra recorded in dried banana, pineapple, papaya, and fig samples resemble the EPR spectrum obtained by computer addition of fructose and glucose spectra taken in proportion 1:1. The decay of radiation induced EPR signals proceeds in dried fruits fast during the first month of observation and becomes much slower and almost negligible after prolonged storage. However, it remains intense enough for EPR detection even one year after processing. The radiation induced EPR signal is easily detected in dried fruits exposed to 0.5 kGy of gamma rays. Thus, the EPR method of the detection of irradiated fruits can be used for the control of dried fruits undergoing quarantine treatment with 200–300 Gy of ionizing radiation.
Źródło:
Nukleonika; 2015, 60, No. 3, part 2; 627-631
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diagnostyka magnetyczna stali paramagnetycznych
Magnetic diagnosis of paramagnetic steels
Autorzy:
Żurek, Z. H.
Cząstkiewicz, Z.
Powiązania:
https://bibliotekanauki.pl/articles/156481.pdf
Data publikacji:
2009
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
diagnostyka magnetyczna stali paramagnetycznych
magnetic diagnosis of paramagnetic steel
Opis:
W stalach paramagnetycznych o możliwościach stosowania diagnostyki magnetycznej decydują przemiany fazowe zachodzące w materiale. Wraz z postępującym procesem obciążeń mechanicznych, eksploatacyjnych zmienia się trwałość austenitu niklowego lub austenitu manganowego. W austenicie stali 18/8, po zgniocie, obserwuje się wydzielenie węglików oraz przemianę fazy γ→α. Przemiana ta wiąże się z utratą własności niemagnetycznych (paramagnetycznych). W materiale niemagnetycznym obserwuje się powstawanie stref materiału o parametrach magnetycznych. Możliwość badania elementów wykonanych ze stali austenitycznych ograniczona była parametrami pomiarowymi urządzeń. W chwili obecnej są dostępne urządzenia umożliwiające bezpośredni pomiar przenikalności magnetycznej z rozdzielczością równą 10-5 µr w dowolnym punkcie na powierzchni materiału. W artykule opisano pomiary dokonane aparaturą sporządzoną w ramach realizacji grantu własnego. Rozdzielczość pomiarowa wykonanego urządzenia umożliwia detekcję zmian przenikalności magnetycznej z rozdzielczością do 10-3 µr. Wykonano pomiary zmian przenikalności magnetycznej na powierzchni zewnętrznej rurki. Metoda punktowego pomiaru przenikalności magnetycznej umożliwia diagnostykę elementów maszyn i konstrukcji, wykonanych ze stali austenitycznych. Dla badanego przypadku wystarczająca okazała się rozdzielczość pomiarowa rzędu 0,001 žr. Diagnostyka wolno zachodzących procesów zmęczeniowych wymaga aparatury badawczej o wyższej czułości. Przedstawiona metoda zapewnia uzyskanie informacji o bezwzględnych zmianach przenikalności magnetycznej i ma przewagę nad metoda opartą na remanencji magnetycznej w polu magnetycznym ziemskim.
Steel is a basic and widely used constructional material. Some steels have ferromagnetic properties, while the others - paramagnetic ones. Use of magnetic diagnosis for this group of materials seems to be obvious due to their magnetic properties. However, magnetic diagnosis is very complex and a lot of factors influence magnetic quantity values. In case of paramagnetic steels the phase changes decide on possibility of using magnetic diagnosis. The durability of nickel or mangan austenitic material changes together with the increase in mechanical load. If 18/8 steel austenite is subjected to cold work, carbides are educed and phase ? changes into phase ?. It results in loss of non-magnetic (paramagnetic) properties. There are observed zones of magnetic properties in a non-magnetic material. One possibility of magnetic testing the paramagnetic steels is illustrated by example of a chromium-nickel austenite pipe. An input pipe segment (shown in Figs.1 and 2) subjected to plastic strain (Figs.3 and 4) is tested. he possibility of testing the austenitic steel elements was limited by the parameters of measurement devices. Nowadays the magnetic permeability can be directly measured and the measurement resolution is equal to 10-5 at any point of the material surface. The paper describes the measurements taken by means of the testing apparatus designed by the author. The measurement resolution makes it possible to detect magnetic permeability changes with the resolution equal to 10-3 žr. The measurements of the pipe outer surface magnetic permeability (see Fig. 6) were taken at the points marked in Fig. 5. The point-by-point method for measuring the magnetic permeability enables diagnosis of machines and other constructionsmade of austenitic steels. In the case considered, the measurement resolution of 0,001 žr proved to be satisfactory. Diagnosis of slow fatigue processes requires testing apparatus of higher sensitivity. The presented method ensures acquisition of information on changes of the absolute magnetic permeability and is superior to the other used methods, especially to those based on magnetic remanence in the Earth's magnetic field.
Źródło:
Pomiary Automatyka Kontrola; 2009, R. 55, nr 4, 4; 229-231
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR studies of free radicals in thermally sterilized famotidine
Autorzy:
Ramos, P.
Pilawa, B.
Stroka, E.
Powiązania:
https://bibliotekanauki.pl/articles/148414.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
free radicals
thermal sterilization
famotidine
electron paramagnetic resonance (EPR) spectroscopy
Opis:
Free radicals formation in thermally sterilized famotidine was studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. The influence of temperature and time of sterilization on free radicals generated in famotidine was determined. The best sterilization conditions for the tested drug were found. Sterilization was done according to the pharmaceutical norms at temperatures 160°C (120 min), 170°C (60 min), and 180°C (30 min). It was pointed out that the optimal temperature of thermal sterilization for famotidine was 170°C and time of heating 60 min in this conditions the lowest free radicals concentration was found. The highest free radicals concentration was measured in famotidine heated at 160°C during 120 min, the long time of sterilization is responsible for this effect. Free radicals concentration changes during storage of famotidine after thermal sterilization. Its value increased with storage time for the drug sterilized at both temperatures of 170°C and 180°C. Free radicals concentration decreases from 7 days after sterilization. Complex system of free radicals with the shape of EPR lines, dependent on microwave power exist in thermally sterilized famotidine. Slow spin-lattice relaxation processes, strong dipolar interactions characterize thermally sterilized famotidine. Microwave saturation indicates that EPR lines of famotidine are homogeneously broadened. The usefulness of EPR spectroscopy to examine of the sterilized drugs was evaluated.
Źródło:
Nukleonika; 2013, 58, 3; 413-418
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 50

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