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1.
BBN (BaBi2Nb2O9) is very interesting and promising lead free material with relaxor properties in capacitors, sensors and actuators. 相似文献
2.
Victor Chabanenko Roman Puźniak Adam Nabiałek Sergei Vasiliev Vladimir Rusakov Loh Huanqian Ritta Szymczak Henryk Szymczak Jan Jun Janusz Karpiński Vitaly Finkel 《Journal of Low Temperature Physics》2003,130(3-4):175-191
We present a study of magneto-thermal instabilities in polycrystalline MgB2 superconductor, by magnetic hysteresis loop measurements and by investigations of magnetic flux dynamics with a miniature Hall probe. Temperature and magnetic field ranges where the flux jumps may be observed have been determined. On the basis of measurements of the magnetic flux dynamics, an average magnetic diffusivity describing the process of the flux jump is estimated. This parameter is compared with the thermal and magnetic diffusivities calculated on the basis of available data for thermal conductivity, heat capacity and resistivity. It is shown that the estimated value of the field of the first flux jump is influenced significantly by the field dependence of specific heat. In order to explain the observed phenomenon, the temperature reached by the sample during the flux jump at different magnetic fields is calculated. 相似文献
3.
J Borysiewicz A Bolek B Prazmowska J Komorowski M Miko?ajska 《Canadian Metallurgical Quarterly》1993,45(3):339-343
Twelve strains of H. pylori were tested. They were isolated from biosamples from 23 patients with stomach inflammation (16 persons) and stomach (3) and duodenum peptic ulcer. By application of solid medium dilution of MIC50 and MIC90-16 antibiotics and antimicrobials were tested. Values of MIC50 and MIC90 for antibiotics from the tetracycline group were, respectively 0.25-0.5 microgram/ml and 0.12-1.0 microgram/ml. Similar results were obtained with macrolide antibiotics. All strains were sensitive to penicillin (MIC 0.03-0.12 microgram/ml, ampicillin (MIC 0.06-0.5 microgram/ml) and amoxicillin and rifampicin (MIC 0.07-0.3 microgram/ml). Ten out of 12 investigated strains were resistant to metronidazole (MIC90 = 30 micrograms/ml). Results of this study may be important for etiotropic treatment of infections with H. pylori. 相似文献
4.
In this paper an analytical method for determining the permeability of nonwoven filter fabrics is presented. The derived formula shows that the intrinsic permeability, fully characterizing the porous medium, depends on fabric porosity, n, fibre diameter, d, and a shape factor determined experimentally. 相似文献
5.
Teresa Mikołajczyk Grażyna Janowska Mariusz Wójcik Maciej Boguń Andrzej Kurzak 《应用聚合物科学杂志》2008,109(4):2513-2521
The rheological properties of spinning solutions of polyacrylonitrile in dimethyl formamide (DMF) containing various amounts of a ferromagnetic nanoaddition were investigated. The porous structure, the strength and thermal properties of fibers obtained from these solutions were assessed, as well as the uniformity of the nanoaddition distribution on the fiber surface was estimated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
6.
Polymeric oxidants in the bead form that were macroporous styrene/divinylbenzene copolymers containing N‐chlorosulfonamide functional groups (in sodium or hydrogen form) or N‐bromosulfonamide groups (in sodium form) were synthesized and investigated to determine their oxidizing powers. The redox potentials of the N‐chlorosulfonamide/sulfonamide and N‐bromosulfonamide/sulfonamide systems were determined by potentiometric studies at different pH values with aqueous solutions of Na2SO3, KCN, and KSCN as reducers. The formal redox potentials of the N‐chlorosulfonamide copolymers were 0.79, 0.44, and ?0.12 V at pH's of 1.8, 8.45, and 13.6, respectively. The formal redox potential of the N‐bromosulfonamide copolymer was about 100 mV higher in comparable conditions and in solutions over pH = 5 (e.g., 0.56 V at pH = 8.56). The comparatively higher oxidizing power of the N‐bromosulfonamide copolymer was particularly evident in a strong alkaline medium (in which the N‐chlorosulfonamide copolymer was not reactive). In contrast, the N‐chlorosulfonamide copolymer showed strong oxidative properties in acidic media (in which the N‐bromosulfonamide copolymer decomposed itself). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
7.
Effect of annealing on the structure and electrical properties of sulfur-doped amorphous c-BN layers
J. Szmidt A. Werbowy L. Jarzebowski T. Gebicki I. Petrakova A. Sokołowska A. Olszyna 《Journal of Materials Science》1996,31(10):2609-2613
Undoped and sulfur doped amorphous cubic boron nitride (a-cBN) layers were deposited on to silicon substrates by reactive pulse plasma (RPP) method. Subsequently they were annealed at 475, 500 and 700 K for 1 h in pure nitrogen atmosphere. In this study structural and electronic properties of unannealed and annealed layers were investigated. The results show that a consequence of annealing is formation of microstructural stable nanocrystalline cubic boron nitride film as well as substitutional location of introducedin situ donor impurities. This resulted in creation of a-cBN(n-type)-Si(p-type) heterojunction. 相似文献
8.
Bronisław Jańczuk Tomasz Białopiotrowicz Emil Chibowski Andrzej Dawidowicz Anna Kliszcz 《Journal of Materials Science》1990,25(3):1682-1685
The contact angles of water drops and diiodomethane drops on pellets made of controlled porosity glasses have been measured. The surface of the glasses was modified by thermal treatment at 873 K which led to an increase in the surface concentration of boron atoms. Glass modified with Carbowax 20M (polyethylene glycol) and fully hydroxylated glass have also been studied. Using the measured contact angles and modified Young equation, the dispersion and nondispersion components of the glass surface free energy have been calculated. The values show that with increasing heating time (increasing surface density of boron atoms) an increase in the surface polarity takes place. However, the polarity of the same samples decreases after treatment with Carbowax, increasingly so with higher boron atom concentrations. 相似文献
9.
M. Sokołowski A. Sokołowska M. Wronikowski T. Kosik 《Journal of Materials Science》1990,25(1):379-383
Optically induced allotropic phase transformations of carbon were studied. Under irradiation with a laser beam of 337.1 nm wavelength, at an energy density of 1.9 mJ per 0.1 mm2, graphite transformed into -carbin, and amorphous carbon-film transformed into rhombohedral graphite with no evidence of high-temperature effects. The transformations differ from the changes occurring due to heating alone. We suggest that the results could be explained by the one-photon excitation and recombination of electrons. 相似文献
10.
M. Sokołowski A. Sokołowska M. Wronikowski T. Kosik 《Journal of Materials Science》1990,25(1):263-267
The optically induced allotropic phase transformations of boron nitride were studied. Under irradiation with laser beam of 337.1 nm wavelength, at energy density of 1.9mJ per 0.1 mm2 a hexagonal boron nitride transformed into the cubic form. The suggestion is made that the results obtained could be explained by the multiphoton excitation and recombination of electrons. 相似文献