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EN
This paper presents the results of studies on the preparation of cellulosic membranes, from a solution in 1-ethyl-3- methylimidazolium acetate (EMIMAc), using the phase inversion method. Initially, the membranes were obtained by coagulation of the polymer film in water and primary alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol), 1-hexanol, 1-octanol) resulting in membranes with significantly differing morphologies. Subsequently, composite membranes were produced, with the support layer being a membrane with the largest pores, and the skin layer a membrane with smaller pores. The resulting membranes were tested for physicochemical and transport properties. The morphology of the membrane surfaces and their cross-sections were investigated by using a scanning electron microscope (SEM). The structure of the membranes, on the other hand, was investigated by FTIR spectroscopy and WAXS structural analysis.
EN
The paper presents results of research on the preparation of cellulose membranes with graphite oxide addition (GO/CEL). Initially, a cellulose (CEL) solution in 1-ethyl-3-methylimidazole acetate (EMIMAc) was obtained, to which graphene oxide (GO) dispersed in N,N-dimethylformamide (DMF) was added. From this solution, composite membranes were formed using phase inversion method. It was observed that the GO addition influences the physico-chemical properties of GO/CEL composite membranes, resulting in an increase in their mass per unit area, thickness and density, and a decrease in sorption properties. In addition, the study of transport properties has shown that GO/CEL membranes do not absorb BSA particles on their surface, which prevents the unfavorable phenomenon of fouling. An important feature of the obtained membranes is the specific permeate flux which reaches high values (~124 L/m2 ×h) at 3.8% of the GO addition to the cellulose matrix.
EN
Natural organic matter (Natural Organic Matter – NOM) represents a mixture of diverse chemical structure and different properties. The humic substances constitute an important component of NOM, and they are responsible for water color and taste, also they can contribute to the formation of disinfection by-products (DBP). Therefore, removal of NOM is considered to be one of the important technological operations during water treatment. The present study evaluate the effectiveness of NOM removal from water by one of the hybrid process and the results showed that the use of this process allows to improve the efficiency of water purification and also reduces the intensity of blocking membranes. Batch adsorption tests of heated aluminum oxide particles (HAOPs) showed that the NOM removal efficiency has been between 86 to 77% at a dose 5 and 10 mg·dm–3, respectively for both tested natural water.
PL
Naturalne związki organiczne (ang. natural organic matter – NOM) są produktami rozkładu organizmów roślinnych i zwierzęcych. Stanowią one mieszaninę o bardzo zróżnicowanej budowie chemicznej i zróżnicowanych właściwościach. Substancje humusowe stanowiące istotny składnik NOM są odpowiedzialne za kolor i smak wody, dodatkowo przyczyniają się do powstawania ubocznych produktów dezynfekcji (DBP). Dlatego usuwanie NOM jest uważane za jedną z istotnych operacji technologicznych w trakcie oczyszczania wód. Zwykle w układach oczyszczania wód powierzchniowych do usuwania zawiesin i NOM wykorzystuje się proces koagulacji połączony z sedymentacją. W ostatnich latach coraz większe zainteresowanie w uzdatnianiu wody do celów pitnych odgrywają procesy membranowe. Przedmiotem badań była analiza skuteczności usuwania naturalnych związków organicznych z wody w procesie hybrydowym, a uzyskane wyniki wskazują, że zastosowanie procesu hybrydowego umożliwia poprawę skuteczności oczyszczania wody, a także ograniczenie intensywności blokowania membran. W obu przypadkach analizowanych wód naturalnych skuteczność usuwania NOM przez HAOPs (heated aluminium oxide particles) mieściła się w zakresie od 86%, gdy stężenie wynosiło 5 mg·dm–3 i 77%, gdy stężenie wynosiło 10 mg·dm–3.
EN
Oxidation experiments were performed in air, in the temperature range 800÷1200°C. They show that CaO sputter coatings on nickel polycrystals have a beneficial influence on both oxidation rates and metal/oxide adherence. The experiments have been analysed taking into account the thermodynamic and transport properties of Ca-doped Ni1–xO single crystals. It appears that the key feature of using CaO coatings are the shift of the Ni/ Ni1–xO phase boundary to higher PO2, the kinetic demixing processes which control the distribution of the cations through the oxidation scale, the localised calcium enriched region near grain boundaries and the blocking effects due to CaO precipitates near the original metal surface position. In view of this analysis and of the comparable properties of Ca-doped Co1–xO and Ni1–xO single crystals, it must be expected that CaO coatings have also a beneficial influence on the oxidation of cobalt base alloys.
PL
W pracy przeprowadzono eksperymenty utleniania w powietrzu, w temperaturze z zakresu 800÷1200°C. Pokazują one, że powłoki CaO napylone na powierzchnie polikryształów niklu mają korzystny wpływ zarówno na szybkość utleniania, jak i na przyczepność warstwy tlenkowej do podłoża metalicznego. Eksperymenty przeanalizowano z punktu widzenia termodynamiki i własności przewodzących domieszkowanych Ca monokryształów Ni1–xO. Wydaje się, że kluczowymi korzyściami stosowania powłok CaO są: przesunięcie granicy faz Ni/Ni1–xO do wartości niższych PO2, procesy kinetycznej separacji kontrolujące rozkład kationów w warstwie tlenkowej, obecność obszarów miejscowo wzbogaconych wapniem w pobliżu granic ziaren i działanie blokujące wydzieleń CaO w pobliżu wyjściowej powierzchni metalu. W świetle przeprowadzonej analizy oraz wyników badań sugerujących podobieństwo własności domieszkowanych Ca monokryształów Ni1–xO i Co1–xO, należy spodziewać się, że powłoki CaO mają także korzystny wpływ na utlenianie stopów na bazie kobaltu. Słowa kluczowe
5
Content available remote Wpływ oparów metalicznych na spawanie łukowe, cz. 2: Obliczanie
PL
W części 2 artykułu omówiono sposoby modelowania i obliczania parametrów łuku spawalniczego w metodach TIG i MIG/MAG. Przedstawiono również metodykę prowadzenia obliczeń właściwości termodynamicznych, współczynników przenoszenia i współczynników dyfuzji.
EN
This part is concerned with computational modeling of welding arcs and the influence of metal vapour. Methods used in modeling, including equations, transport properties, treatment of metal vapour diffusion, radiative emission coefficients and vaporization rates are presented.
6
EN
The oxidation results of dilute Ni-Al (<5 wt. %) alloys at 700÷1200°C hale been analyzed taking into account the transport properties of pure and Al doped-Ni1-xO single crystals, at equilibrium and in transient conditions. A formal treatment of transport processes under non-equilibrium conditions, coupled to the set of experimental results concerning the influence of Al on the transport properties of Ni1-xO, has allowed to analyze the influence of Al on nickel oxidation. We have shown both, that the solute cation enrichment near the metal/oxide interface is due to kinetic demixing processes taking place in the growing oxide layer, with DAl < DNi, and that the increase of the alloy oxidation velocity at T > 900°C is caused by oxygen molecules which penetrate the oxide scale along cracks or fissures. These short-circuit paths are likely generated by non uniform stresses due to blocking effects on the diffusion of Ni2+ ions through the scale, leading to the growth of oxide particles within the oxide itself.
PL
Badano proces utleniania stopu Al-Ni (<5% mas.) w zakresie temperatury 700÷1200°C z uwzględnieniem procesów dyfuzyjnych zachodzących w czystych i domieszkowanych Al monokryształach Ni1-xO, w warunkach równo - i nierównowagi. Obliczenia teoretyczne dla warunków nieustalonych oraz wyniki badań eksperymentalnych pozwoliły przeanalizować wpływ Al na dyfuzję w Ni1-xO, a tym samym wyjaśnić wpływ Al na utlenianie niklu. Wykazano, że wzrost koncentracji kationów na granicy metal/tlenek wynika z kinetyki rozdziału składników, jaki ma miejsce w czasie wzrostu warstwy tlenku (DAl < DNi), jak również, że wzrost szybkości utleniania stopu w T > 900°C jest spowodowany łatwą dyfuzją tlenu w warstwie tlenku poprzez pęknięcia i szczeliny. Te drogi łatwej dyfuzji powstają w wyniku generowania naprężeń wskutek hamowania dyfuzji Ni2+ w warstwie tlenków i zjawiska wewnętrznego utleniania w warstwie tlenku.
EN
The aim of this study is the theoretical investigation of transport properties in non-equilibrium plasmas, taking into account the influence of electromagnetic fields. The formalism of generalized Chapman-Enskog method based on the hierarchy of characteristic times of various collision processes is used to provide a closed description of kinetics, dynamics and transport phenomena in a partially ionized gas with non-equilibrium ionization reactions. Distribution functions, governing equations, transport and production terms are derived in the zero and the first-order approximations of the Chapman-Enskog method corresponding to inviscid non-conductive and viscous conductive flows respectively.
EN
The paper develops a new statistical formulation to calculate the thermal diffusivity, binary diffusion coefficient, thermal diffusion factor, viscosity and thermal conductivity of gas mixtures with non-equilibrium statistical mechanics. For the analytical calculation of transport properties, the models of Kihara and Chapman-Cowling (up to the third order) have been used. Thermal transport properties for mixtures involving carbon monoxide, helium, argon, xenon and krypton have been computed with the new formulation in this paper. New mixing rules for the calculation of transport properties for mixtures are developed. Close agreement is obtained between the analytical results (based on statistical mechanics) and experimental data. The results exhibit comparable or better accuracy than previous methods, while providing new insight regarding the detailed statistical mechanisms of intermolecular interactions, as they contribute to the transport property variations with temperature.
9
EN
Sandwich samples of the type (Au-CdPc-Al) have been fabricated by successive vacuum deposition of gold (Au), cadmium phthalocyanine (CdPc), and aluminium (Al) thin films on glass substrates. Good rectification properties have been observed in the device. Ohmic conduction in the lower voltage range has been identified from the forward bias current density-voltage characteristics at room temperature. At higher voltages, a space charge limited conductivity (SCLC) controlled by an exponential trapping distribution above the valence band edge has been observed. The transport properties of the material at ambient temperature have been obtained from an analysis of the samples in the SCLC region. Schottky emission has been identified at lower voltages from the analysis of the reverse bias characteristics.
PL
Otrzymywanie czystych epitaksjalnych warstw InAs/GaAs o dużej perfekcji krystalograficznej jest możliwe metodą epitaksji z wiązek molekularnych [2]. W warstwach tych obserwowane jest anomalne zachowanie R H (T) tj. występowanie maksimum w temperaturach około 50K i spadek wartości poniżej tej temperatury, co odpowiada anomalnej zależności n H (T). W warstwach InAs w niskich temperaturach w wyniku występowania naprężeń (skutkiem niedopasowania sieciowego) występują anomalne zjawiska transportu [3]. Stwierdzono w przypadku występowania anomalnych wartości R H w InAs, że dla poprawnego rozwiązania równania neutralności należy dodać do koncentracji elektronów dodatkowy składnik X, związany ze stanami typu donorowego i akceptorowego [2]. Składnik X mogą stanowić domieszki o różnych energiach aktywacji położonych pod dnem lub nieco ponad dnem pasma przewodnictwa.
EN
Molecular beam epitaxy allow to obtain pure InAs layers with big crystallographic perfection [2]. We observed in this layers anomalous behaviour of R H (T) ie. Maximum value at temperature ~50K and decrease in temperature lower as 50K what is equivalent to anomalous increase of n H (T). In the epitaxial layers of InAs at low temperatures as a result of of strain between the layer and GaAs substrate we observe the transport by two or more charge carriers [3]. It was stated, that in the case of anomalous values of R H (T) we must add to concentration of charges the component X during solving of the neutrality equation. This component may be acceptor or donor like [2]. X component may be energetically localized little under bottom of conductivity band or above it.
EN
La1-xSrxCo1-y-zFeyNizO3 perovskites have been synthesized with hexagonal R-3c structures by a modified citric acid method and determined their structural and transport properties. Structural instabilities for samples with high Ni and Sr content heated to 1270 K were observed, leading to the appearance of secondary phases with spinel structures. Moessbauer studies revealed the presence of two different, clearly distinguishable surroundings of Fe ions, despite single crystallographic positions of iron ions. Low-temperature (77-300 K) dc conductivity and thermoelectric power measurements suggest an activated charge transport mechanism with the activation energy strongly dependent on the chemical composition of the material. Electrical conductivity as a function of temperature suggests the appearance of a hopping mechanism. The observed hightemperature (870-1070 K) dc electrical conductivity of La1-xSrxCo1-y-zFeyNizO3 samples is relatively high and strongly depends on chemical composition. It seems possible to optimise the transport properties of La1-xSrxCo1-y-zFeyNizO3 by chemical composition, which may lead to a new, attractive cathode material in terms of possible applications in intermediate -temperature solid-oxide fuel cells (IT-SOFCs).
12
Content available remote Growth and properties of MOCVD HgCdTe epilayers on GaAs substrates
EN
Growth of MOCVD Hg1-xCdxTe (HgCdTe) epilayers on GaAs substrates is described. The paper focuses on the interdiffused multilayer process (IMP). In this process, the CdTe/HgTe growth times are comparable with transition times between the phases. The non-optimum flow velocities and partial pressures that may induce poor morphology and reduce growth rate characterize the growth during transition stages. The optimum conditions for the growth of single layers and complex multilayer heterostructures have been established. One of the crucial stages of HgCdTe epitaxy is CdTe nucleation on GaAs substrate. Successful composite substrates have been obtained with suitable substrate preparation, liner and susceptor treatment, proper control of background fluxes and appropriate nucleation conditions. Due to the large mismatch between GaAs and CdTe, both (100) and (111) growth may occur. It mostly depends on substrate disorientation and preparation, nucleation conditions and growth temperature. Cd or Te substrate treatment just before growth results in (100) and (111) orientation, respectively. Generally, layers with orientation (100) show superior morphology compared to (111) but they are also characterized by hillocks. The benefits of the precursors ethyl iodine (EI) and arsine (AsH3) for controlled iodine donor doping and arsenic acceptor doping are summarized. Suitable growth conditions and post growth anneal is essential for stable and reproducible doping. In-situ anneal seems to be sufficient for iodine doping at any required level. In contrast, efficient As doping with near 100% activation requires ex-situ anneal at near saturated mercury vapours. The transport properties of HgCdTe epilayers indicate on achieving device quality material. Reproducible n- and p-type doping at the low, intermediate and high level (1015-1018 cm-3) has been achieved with stable iodine and arsenic dopants. The mobilities and carrier lifetimes achieved for extrinsically doped n-type and p-type layers follow essentially the same trends observed in state-of-the-art liquid phase epitaxy grown HgCdTe.
PL
Opisano otrzymywanie polikrystalicznych próbek CoSb₃ typu p i n domieszkowanego Sn i Te. Wykonano badania strukturalne, analizę składu oraz pomiary właściwości termoelektrycznych. Określono optymalne zawartości domieszek w celu uzyskania maksymalnej wartości współczynnika etektywności termoelektrycznej ZT.
EN
Polycrystalline p and n doped CoSb₃ materials with various contents of Sn and Te have been obtained. Structural, phase analysis and thermoelectric properties have been investigated. Optimal contents of impurities for maximum figure of merit ZT have been determined.
EN
Spectral investigations of new organic conductors (BEDO-TTF)2(C3H2N3O3) and (DB-TTF) (C3H2N3O3) were performed. Optical absorption spectra in the range of 400-40 000 cm-1 of the powdered salts dispersed in KBr pellets were recorded and analysed. The spectra of (BEDO-TTF)2(C3H2N3O3) are characteristic of organic metals and show small anisotropy, which is typical of quasi-two-dimensional materials. On the other hand, the spectra of (DB-TTF)(C3H2N3O3) are typical of semiconducting materials. The (BEDO -TTF)2(C3H2N3O3) salt undergoes a phase transition at about 120 K. The polarized reflectance spectra of single crystals of (BEDO-TTF)2(C3H2N3O3) were recorded in the range of 600-7000 cm-1, down to 4 K. The frequency dependences of reflectivity were fitted with a Drude model and the transport parameters were evaluated and investigated vs. temperature. An assignment of some vibrational bands in the IR spectra was proposed.
15
Content available remote Some new findings in t-phase organic conductors
EN
Some new findings concerning the structural, optical, transport, and magnetotransport properties of t-phase organic conductors, based on the donor molecules ethylenedioxy-S,S-dimethylethylenedithiotetrathiafulvalene, ethylenedioxy-R,R-dimethylethylenedithio-tetrathiafulvalene, pyrazino-S,S-dimethylethylenedithio- tetrathiafulvalene, pyrazino-R,R-dimethylethylenedithio-tetrathiafulvalene, pyrazino-r-dimethylethylenedithio- tetrathiafulvalene, pyrazino-S,S-dimethylethyledithio-diselenadithiafulvalene, pyrazino- r-methylethylenedithio-tetrathiafulvalene, and pyrazino-r-methylethylenediseleno-tetrathiafulvalene are described. Some similarities and differences in their properties are discussed.
EN
The paper features theoretical model of computing (based on methods of statistical thermodynamics and kinetic theories of gas) viscosity and thermal conductivity in the liquid and gas domain for pure components. To calculate the viscosity of real fluid, the models developed on the basis of Lennard-Jones intermolecular potential are applied. Heat capacities are calculated by use of statistical thermodynamics. The paper features all important contributions (translation, rotation, internal rotation, vibration, intermolecular potential energy and influence of electron and nuclei excitation). The analytical results obtained by statistical thermodynamics are compared with the REFPROP model and show relatively good agreement.
17
Content available remote Chaos i fraktale w opisie struktury i morfologii polimerów
PL
Scharakteryzowano zastosowanie nowego typu analizy opartej na koncepcjach chaosu i fraktali do rozwiązywania problemów strukturalno-morfologicznych materiałów polimerowych. Uogólniony wymiar fraktalny, system odwzorowań zwężających (IFS) oraz quasi-izomorfizrn wykorzystano jako narzędzia służące do różnicowania struktur i badania ich samopodobieństwa. Przedstawiono nowy sposób badania związku między strukturą a właściwościami transportowymi polimerów na podstawie pomiaru natężenia prądu jonowego, na przykładzie prądu potasowego płynącego przez membranę z poli(tereftalanu etylenu). Przedyskutowano pojęcia struktury transportowej i struktury topologicznej polimeru. Wykładnik a w fenomenologicznej zależności Marka-Houwinka wiążącej graniczną liczbę lepkościową z ciężarem cząsteczkowym polimerów został zredefiniowany [równanie (8)] i powiązany z charakterem struktury polimeru w roztworze (polimer liniowy lub dendrytyczny).
EN
A new type of analysis based on the concepts of chaos and fractals is applied to solve the structure and morphology problems in polymeric materials. The generalized fractal dimension, iterated function system (IFS) and the quasi-isomorphism are used to differentiate structures and to study their self-similarity. A new approach is presented to study the relationship between the structure and the transport properties of polymers, based on the measurements of ionic current, exemplified by a potassium ion current flowing through a poly(ethylene terephthalate) membrane. The concepts of transport and the topological structures of a polymer are discussed. The exponent a in the phenomenological Mark-Houwink relationship for polymers, eqn. (8), was redefined and related to the structure of the polymer in the solution (linear or dendritic polymer).
EN
Transport coefficients for partially ionized Fe vapour plasmas are determined according to Chapman-Enskog method of fourth order. Results corresponding to the conditions within the keyhole formed during laser welding of steel are presented.
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