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Wyszukujesz frazę "Kempiński, W." wg kryterium: Autor


Tytuł:
Auxetics as entropy filters - possible application
Autorzy:
Wojciechowski, K. W.
Kempinski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1938609.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska
Tematy:
superfluidity
entropy filters
auxetics
3He isotope
Opis:
In this note a sketch of the idea of applying auxetics to separation of 3He from a mixture of 4He and 3He by using auxetic entropy filters is presented.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2016, 20, 3; 271-272
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charakterystyka reologiczna procesu sedymentacji i erozji namułów rzecznych
Reological characteristics of sedimentation process and erosion of river sediments
Autorzy:
Glowski, R.
Parzonka, W.
Kempinski, J.
Eckstadt, H.
Powiązania:
https://bibliotekanauki.pl/articles/60269.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Infrastruktura i Ekologia Terenów Wiejskich PAN
Tematy:
koryta rzeczne
dynamika zmian
rumowiska unoszone
osady rzeczne
wlasciwosci reologiczne
sklad granulometryczny
zawartosc czesci organicznych
gestosc szkieletu gruntowego
wilgotnosc naturalna
granica plynnosci Atterberga
sedymentacja
namuly rzeczne
erozja hydrauliczna
Opis:
Autorzy przeprowadzili ocenę dynamiki zmian koryt rzecznych spowodowanych przez procesy sedymentacyjne i erozyjne. Zbadano cechy fizyczne i reologiczne wybranych osadów spoistych i częściowo spoistych. Próbki osadów pochodziły z nizinnych odcinków rzeki Odra (Polska) i rzeki Warnow (Niemcy). Charakterystyki reologiczne zbadano za pomocą wiskozymetrów rotacyjnych. Badane namuły miały cechy typowe dla cieczy nienewtonowskich. Charakterystyki erozyjne wyznaczono na podstawie metodyki Migniota. Sprawdzono je w skali naturalnej po przejściu fali powodziowej przez stopień Brzeg Dolny, która spowodowała częściowe wymycie osadów z górnego stanowiska jazu.
The authors performed an estimation of the dynamic of the river bed changes caused by sedimentation and erosion processes. The physical and rheological parameters for chosen cohesive and semi-cohesive sediments were investigated. Mud samples were taken from 3 different localisation on Middle Odra (Poland) and from 2 localisations on Warnow river (Germany). Rheological characteristics were studied with use of the rotative viscometer. Erosion characteristics of the mud’s were studied accordingly to methodology of Migniot [1968]. Results for Middle Odra were verified in the natural scale during the passage of the catastrophic flood through barrage Brzeg Dolny in 1997. This flood caused partly erosion of mud’s from the upstream part of this barrage.
Źródło:
Infrastruktura i Ekologia Terenów Wiejskich; 2007, 4/2
1732-5587
Pojawia się w:
Infrastruktura i Ekologia Terenów Wiejskich
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electric Conductivity of Carbon Nanoparticles Stimulated by Electric Field
Autorzy:
Markowski, D.
Kempiński, W.
Kempiński, M.
Trybuła, Z.
Kaszyńska, K.
Śliwińska-Bartkowiak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1535906.pdf
Data publikacji:
2010-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.Pr
73.21.La
73.23.Hk
73.25.+i
73.63.-b
73.23.-b
Opis:
Host-guest interactions can be the unique method of spin manipulation in nanoscale. Strong changes in spin localization are generated when potential barriers between nanographitic units of activated carbon fibers are modified by interaction with adsorbed molecules. Stronger modifications occur when dipolar guest molecules are stimulated with external electric field. We report experimental results which show the influence of electric field on the spin localization in activated carbon fibers.
Źródło:
Acta Physica Polonica A; 2010, 118, 3; 457-458
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR and Impedance Measurements of Graphene Oxide and Reduced Graphene Oxide
Autorzy:
Kempiński, M.
Łoś, S.
Florczak, P.
Kempiński, W.
Jurga, S.
Powiązania:
https://bibliotekanauki.pl/articles/1033701.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Vp
76.30.-v
Opis:
We report the observations of electron paramagnetic resonance and impedance measurements of graphene oxide and reduced graphene oxide performed in the wide temperature range in order to get insight into the electronic properties of graphene-based materials and the role of oxygen functionalities in the charge carrier transport phenomena. In such systems the strong spin localization, hopping charge carrier transport as well as the formation of adsorption layers are observed, all the phenomena changing significantly after the heavily oxidized graphene is reduced.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 81-85
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR and MMMA Study of C$\text{}_{60}$ upon K-Doping
Autorzy:
Kempiński, W.
Stankowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933662.pdf
Data publikacji:
1995-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Wz
76.30.-v
Opis:
EPR and ΜΜMΑ studies of C$\text{}_{60}$ upon K-doping have been performed. Two different and well separated EPR narrow lines were detected for C$\text{}_{60}^{1-}$ and C at temperatures below 100 K. Time dependent changes in the intensities of both and C$\text{}_{60}^{3-}$ lines were observed when the system undergoes an eutectoid transformation. The evolution of superconductivity with two T$\text{}_{c}$ related to different valences (v) of C$\text{}_{60}^{v}$ ion radicals have been found.
Źródło:
Acta Physica Polonica A; 1995, 88, 3; 549-552
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Formation of Superconducting Regions of MgB_2 by Implantation of Boron Ions into Magnesium Substrate
Autorzy:
Trybuła, Z.
Kempiński, W.
Andrzejewski, B.
Piekara-Sady, L.
Kaszyński, J.
Piekoszewski, J.
Werner, Z.
Richter, E.
Prokert, F.
Stanisławski, J.
Barlak, M.
Powiązania:
https://bibliotekanauki.pl/articles/2043433.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
74.78.-w
Opis:
The results of investigation of the MgB$\text{}_{2}$ inter-metallic compound with the use of boron ions implantation and plasma pulse treatment are presented. The samples were characterized by: four-probe electric conductivity measurements, magnetically modulated microwave absorption, and magnetic measurements. For hydrogen and argon pulsed plasma treatment the samples with T$\text{}_{c}$ ranging from 10 K to 32 K were obtained. The superconducting phase does not form a continuous layer since the resistivity does not fall down to zero. Apparently, separate islands of superconducting phase are connected through metallic Mg paths. All samples are still below the percolation threshold.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 165-170
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Free Radicals in K and Rb Admixtured Fullerene C$\text{}_{60}$
Autorzy:
Stankowski, J.
Kempiński, W.
Byszewski, P.
Trybuła, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1929831.pdf
Data publikacji:
1993-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Rn
74.70.Wz
Opis:
Molecules of C$\text{}_{60}$ form Van der Waals type crystals. The observations reported here concern EPR investigations of such C$\text{}_{60}$ samples with only a slight amount of Rb or K. Detected defects are (C$\text{}_{60}$)$\text{}^{+}$ or (C$\text{}_{60}$)$\text{}^{y-}$ ion-radicals. A hole (h) or trapped electron (t) are localized on one fullerene ball. In the case of potassium fullerites C$\text{}_{60}$:K the line shape of EPR signal was of the Dysonian form which is characteristic of conducting electrons in metal. The EPR lines of holes (C$\text{}_{60}$)$\text{}^{+}$ are characterized by g$\text{}_{h}$ ≥ g$\text{}_{0}$ whereas for electrons g$\text{}_{t}$ is below the value g$\text{}_{0}$ = 2.0023 characteristic of a free electron (g$\text{}_{t}$ ≤ g$\text{}_{0}$). The EPR linewidth 2ΔB$\text{}_{1s}^{h}$ of the (C$\text{}_{60}$)$\text{}^{+}$ weakly increased with decreasing temperature whereas the EPR linewidth attributed to the electron 2ΔB$\text{}^{t}$$\text{}_{1s}$ significantly decreases with decreasing temperature. The C$\text{}_{60}$:K sample reached superconducting phase below T$\text{}_{c}$ = 11 K which is significantly less than T$\text{}_{c}$ = 16.5 K observed for K$\text{}_{x}$C$\text{}_{60}$ where 2 ≤ x ≤ 4.
Źródło:
Acta Physica Polonica A; 1993, 84, 6; 1117-1123
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ion Implantation and Transient Melting: A New Approach to Formation of Superconducting MgB$\text{}_{2}$ Phases
Autorzy:
Piekoszewski, J.
Kempiński, W.
Stankowski, J.
Prokert, F.
Richter, E.
Stanisławski, J.
Werner, Z.
Szymczyk, W.
Powiązania:
https://bibliotekanauki.pl/articles/2041609.pdf
Data publikacji:
2004-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
74.78.-w
Opis:
An attempt to synthesize superconducting MgB$\text{}_{2}$ inter-metallic compound from the liquid state is presented. The process consists of two steps. In the first one, boron ions are implanted into a magnesium substrate. In the second one, the near-surface region of such system is melted by short, intense hydrogen plasma pulses without necessity of annealing in Mg vapor. A magnetically modulated microwave absorption method was used to detect superconducting regions in the obtained MgB$\text{}_{2}$ layer. Percolation between nano-regions (islands) of MgB$\text{}_{2}$ has not been observed. However, a superconducting state of the insulated islands has been experimentally proven with transition temperatures T$\text{}_{C}$ as high as 31 K.
Źródło:
Acta Physica Polonica A; 2004, 106, 6; 861-868
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Localized states in nanocarbons
Autorzy:
Kempiński, W.
Kempiński, M.
Markowski, D.
Łoś, M.
Powiązania:
https://bibliotekanauki.pl/articles/148234.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
activated carbon fibers (ACF)
carbon nanotubes
electron paramagnetic resonance (EPR)
fullerenes
Opis:
Localization phenomenon is studied in different modern nanocarbon materials: pristine C60, C60-fullerides, carbon nanotubes and graphene-based structures in the form of activated carbon fibers built of quantum dot-like basic structural units. Two experimental methods are used to define the localization and population control of spins (charge carriers) in the nanocarbon materials – electron paramagnetic resonance (EPR) and direct current (d.c.) electrical conductivity measurements. Results are discussed in the frame of the possible applications of the aforementioned materials in the molecular electronics or spintronics.
Źródło:
Nukleonika; 2013, 58, 3; 371-373
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxygen Deficient YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$: Two Superconducting Phases
Autorzy:
Stankowski, J.
Ślązak, A.
Kempiński, W.
Andrzejewski, B.
Reichel, B.
Plesch, G.
Powiązania:
https://bibliotekanauki.pl/articles/2037166.pdf
Data publikacji:
2004-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.62.Bf
74.62.-c
74.25.Nf
Opis:
A set of oxygen deficient powder and granular samples of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ ceramics was studied by means of thermogravimetric and magnetically modulated microwave absorption methods. Especially the last method has turned out to be a powerful method, which was used to determine the dependence of critical temperature T$\text{}_{c}$ on the oxygen parameterδ. Using these methods it has been shown that the removing of oxygen evokes the inhomogeneous oxygen distribution in the samples and a change in carrier concentration till to the loss of superconducting properties. A superconducting phase with T$\text{}_{c}$=60 K, which occurs in oxygen deficient YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ sample, is an unstable phase.
Źródło:
Acta Physica Polonica A; 2004, 105, 3; 287-294
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pseudorotational Averaging of EPR Spectrum of Cu(II)O$\text{}_{5}$ Complex in YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ in Low Temperatures
Autorzy:
Stankowski, J.
Kempiński, W.
Trybuła, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1891644.pdf
Data publikacji:
1991-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.-f
74.70.Vy
76.30.Fe
Opis:
In low temperatures the condensation of oxygen was found to occur at 05 site in an elementary cell of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ being the fifth ligand forming the CuO$\text{}_{5}$ complex around Cul copper in chain. This change of coordinantion from CuO$\text{}_{4}$ to CuO$\text{}_{5}$ is the origin of a pseudorotation related to a strong vibronic coupling of two distorted configurations: a tetragonal pyramid C$\text{}_{4v}$ and a trigonal bipyramid D$\text{}_{3h}$, which yields a pseudocubic EPR spectrum in low temperatures. The averaged spectroscopic splitting coefficient is related to a superposition of vibronically coupled orbital states |x$\text{}^{2}$ - y$\text{}^{2}$〉 and |3z$\text{}^{2}$ - r$\text{}^{2}$〉. The averaged spectrum was for the first time observed in low temperatures since the oxygen condensation in YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ at 05 site of the chain occur only when oxygen undergoing fast diffusion among the chains, gets localized with decreasing temperature. The activation energy of oxygen desorption from the 05 site is 36 K.
Źródło:
Acta Physica Polonica A; 1991, 80, 4; 571-581
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size Modification of Nanographite System of Activated Carbon Fibers Studied by EPR
Autorzy:
Kempiński, M.
Kempiński, W.
Śliwińska-Bartkowiak, M.
Powiązania:
https://bibliotekanauki.pl/articles/2043617.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.81.Uv
73.20.-r
73.22.-f
76.30.-v
74.78.Na
Opis:
We report results of EPR measurements of activated carbon fibers. Experiments made for pristine activated carbon fibers and activated carbon fibers with adsorbed molecules (CCl$\text{}_{4}$, C$\text{}_{6}$H$\text{}_{5}$NO$\text{}_{2}$, and H$\text{}_{2}$O) confirmed the localized character of paramagnetic centers observed in the system. Pristine activated carbon fibers are characterized by single Lorentzian line. Broader component of EPR signal appears when guest molecules are adsorbed in nanopores. The strongest localization is observed for water-filled activated carbon fibers nanopores (with hydrophobic pore walls) where changes in distance between nanographite particles were monitored by the g-shift to higher values. This process is related to stronger spin-orbit interaction of electrons trapped at nanographite particles compressed by guest molecules.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 339-343
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Regions and Kondo Effect of MgB$\text{}_{2}$ Formed by Implantation of Magnesium Ions into Boron Substrate
Autorzy:
Trybuła, Z.
Kempiński, W.
Andrzejewski, B.
Piekara-Sady, L.
Kaszyński, J.
Trybuła, M.
Piekoszewski, J.
Stanisławski, J.
Barlak, M.
Richter, E.
Powiązania:
https://bibliotekanauki.pl/articles/2046803.pdf
Data publikacji:
2006-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
74.78.-w
Opis:
The results of investigation of the polycrystalline boron implanted by magnesium and argon plasma pulse treatment are presented. The four-probe electric conductivity measurements and magnetically modulated microwave absorption showed the presence of superconducting islands below the temperature of 25 K. Below T=23 K we detected the Kondo effect, a logarithmic increase in the resistivity as the temperature is lowered, due to iron impurity.
Źródło:
Acta Physica Polonica A; 2006, 109, 4-5; 657-660
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity of $MgB_2$ Layers Prepared on Silicon Substrate by Implantation of Magnesium Ions into Boron Substrate
Autorzy:
Trybuła, Z.
Kempiński, W.
Łoś, Sz.
Kaszyńska, K.
Trybuła, M.
Piekoszewski, J.
Werner, Z.
Barlak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1536977.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
74.78.-w
Opis:
The results of investigation of the $MgB_2$ layers prepared on silicon substrate by implantation of Mg ions into boron substrate are presented. After implantation the annealing processes were carried out at temperatures 673 K, 773 K, and 873 K in a furnace in an atmosphere of flowing Ar-4%$H_2$ gas mixture. The samples were characterized by: four-probe electric conductivity measurements and magnetically modulated microwave absorption. Our results showed that due to silicon substrate the diffusion of implanted Mg ions into boron materials should be limited, and the superconducting phase forms a continuous $MgB_2$ layer and the resistivity for all samples fall down to zero below $T_{c}$. The transition temperature $T_{c}$ becomes higher with increasing annealing temperature: $T_{c}$=18 K (for annealing at $T_{A}$=673 K), $T_{c}$=20 K (for annealing at $T_{A}$=773 K), and $T_{c}$=27 K (for annealing at $T_{A}$=873 K).
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 323-325
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity of Carbon Materials - Unstable Phases
Autorzy:
Kempiński, W.
Powiązania:
https://bibliotekanauki.pl/articles/2038391.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
74.70.Wz
Opis:
Different intercalated carbon systems: K$\text{}_{x}$C$\text{}_{60}$, Rb$\text{}_{x}$C$\text{}_{60}$ as well as highly oriented pyrolytic graphite + potassium with unstable structural and superconducting behavior were investigated with the EPR and magnetically modulated microwave absorption techniques. Three characteristic, well-separated EPR signals were observed for A$\text{}_{x}$C$\text{}_{60}$ (A = K or Rb) systems at the early stages of doping process. We ascribed these signals to C$\text{}_{60}^{+}$, C$\text{}_{60}^{1-}$, and C$\text{}_{60}^{3-}$ radicals. Evolution of the EPR spectrum characterizes different phases of K$\text{}_{x}$C$\text{}_{60}$ system including superconducting one. Two superconducting phases with T$\text{}_{c}^{(1)}$=(21±0.5) K (unstable) and T$\text{}_{c}^{(2)}$=(18.5±0.5) K (final, stable) were distinctly separated for K$\text{}_{x}$C$\text{}_{60}$ system. For C$\text{}_{60}$ intercalated by rubidium a similar evolution of EPR spectrum is observed. Prior to well-defined superconducting Rb$\text{}_{3}$C$\text{}_{60}$ phase was created, strong instabilities of the magnetically modulated microwave absorption signal were observed at the narrow part of the doping process. For potassium intercalated highly oriented pyrolytic graphite, EPR oscillations below 100 K were observed as well as Josephson hysteresis loops were registered at 5 K.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 627-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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