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1

Diffuse-layer surface potentials of colemanites mined in Turkey

Senol-Arslan Dilek, Drelich Jaroslaw W.

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 5

art. no. 151933

EN

Colemanite crystal specimens were handpicked at Kestelek, Emet (Hisarcik, Espey), Bigadic mines in Turkey for characterization of their composition and surface potential. X-ray diffraction analysis revealed no differences in mineralogical makeup of the crystals, but elemental analysis indicated differences in the type of trace (<0.1 wt%) elements. Zeta potential measurements showed small differences in zeta potential values, with isoelectric points (iep) varying from about pH = 9.6 to pH = 10.2. However, no correlation was found between iep and the type of trace elements. Additionally, atomic force microscopy (AFM) was employed to measure the colloidal interactions between a silicon nitride (Si3N4) cantilever tip and colemanite crystal surfaces in 1 wt% colemanite-saturated aqueous solutions at three different pHs (8.4, 9.4 and 11). The Derjaguin-Landau-Verwey-Overbeek theory (DLVO) was applied to examine the AFM tip interactions with colemanite surfaces in an aqueous solution of colemanite saturated solutions. The results revealed attractive forces at pH = 8.4 and 9.4 and repulsive forces at pH = 11, confirming the location of an isoelectric point for colemanite specimens somewhere between pH = 9.5 and pH = 10.1. Theoretical analysis of the force curves using the DLVO theory allowed for assessment of both surface charge density and surface potential for colemanite specimens used in this study.

2

Dispersive effect of low molecular weight sodium polyacrylate on pyrite-serpentine flotation system

Zhao K., Yan W., Wang X., Gu G., Deng J., Zhou X., Hui B.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

1200--1213

EN

In this work, the dispersive effect of low molecular weight sodium polyacrylate (PAAS) on serpentine, and its dispersion mechanism were systematically investigated through zeta potential measurements, micro and batch flotation as well as adsorption tests. At pH 5, where flotation of iron sulphide was routinely performed, pyrite and serpentine minerals were oppositely charged, and therefore they were attracted to each other. Slime coatings of serpentine adhered to the surface of pyrite, decreasing the adsorption density of a collector on the pyrite surface, but also reducing the flotation recovery. PAAS increased the flotation recovery of pyrite by promoting dispersion between pyrite and serpentine. The effective flotation separation of pyrite from the refractory iron sulphide ore was possible by using PAAS as a dispersant. Anionic PAAS adjusted the surface potential of serpentine through adsorption on the serpentine surface and changed the interaction between pyrite and serpentine particles from attractive to repulsive, and then dispersed pyrite and serpentine.

3

Zanik ładunku na izolatorach kompozytowych

Kacprzyk R., Pelesz A.

Przegląd Elektrotechniczny

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2014

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R. 90, nr 10

16-18

PL

Zbadano proces zaniku ładunku powierzchniowego na cylindrycznych kompozytowych izolatorach zawierających różne kombinacje materiałów rdzenia i płaszcza. Izolatory zostały poddane „punktowej” elektryzacji za pomocą wyładowania koronowego przy napięciu stałym. Wyniki badań wykazały zależność szybkości zaniku ładunku od materiału płaszcza jak i rdzenia przy czym transport ładunku ma miejsce głównie w płaszczu. Stwierdzono również wpływ interfazy rdzeń-płaszcz na szybkość zaniku ładunku.

EN

Surface charge decay process was examined on cylindrical composite insulators models with various combinations of core and housing materials. Insulator models were subjected to “point” electrification by DC corona discharge. The results showed that the rate of charge decay depend on the material of the core and the housing wherein the charge transport takes place primarily in the housing. It was also found the influence of core-housing interphase on the rate of charge decay.

4

Rozwój metod badawczych związanych z Dyrektywą ATEX w Laboratorium Badań Stosowanych

Kamiński T., Lesiak K., Orzech Ł., Talarek M.

Maszyny Górnicze

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2014

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R. 32, nr 1

29--35

PL

W artykule przedstawiono nowe metody badawcze związane z Dyrektywą ATEX wdrożone do stosowania w Laboratorium Badań Stosowanych. Przedstawiono możliwości badawcze nowo zakupionego wyposażenia i stanowisk badawczych. Zaprezentowano wyniki badań rozkładu potencjału powierzchniowego po wystąpieniu wyładowania z powierzchni materiałów nieprzewodzących. Zaprezentowano przebieg wybuchu mieszaniny metanowo-powietrznej podczas badań małych elementów. Opisano stanowisko do badań osłon ognioszczelnych „d” i zaprezentowano zarejestrowany przebieg zmian ciśnienia podczas wybuchu podstawowych mieszanin gazowych stosowanych w badaniach.

EN

New testing methods associated with ATEX Directive implemented in the Laboratory of Applied Tests are presented. Testing potential of newly purchased equipment and tests stands is given. The results of testing the distribution of surface potential after discharge from non-conducting materials are presented. Process of explosion of methane-air mixture during testing of small components is given. Stand for testing the “d” fireproof shields is described and the recorded curve of pressure changes during explosion of tested main flammable gases is shown.

5

KFM calibration method

Jabłoński R., Ligowski M., Tabe M.

Elektronika : konstrukcje, technologie, zastosowania

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2013

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Vol. 54, nr 6

19-21

PL

Istnieje wiele sposobów kalibracji kelvinowskiego mikroskopu sił atomowych (Kelvin Probe Force Microscope, KFM) [1], a uzyskane dokładności zależą od wybranej metody. W publikacji przedstawiona jest nowa metoda wzorcowania KFM. Metoda jest oparta na pomiarze potencjału powierzchniowego wzorca odniesienia i porównaniu wyniku z uzyskanym za pomocą KFM. Pozwala ona na wzorcowanie w całym zakresie pomiarowym mikroskopu zarówno w wartościach bezwzględnych jak i dynamicznie zmiennych. Napięcie powierzchniowe wzorca odniesienia użytego do wzorcowania jest regulowane w zależności od potrzeb (nie jest więc zdefiniowane jego fizycznymi parametrami). Stosując tą metodę zarówno charakterystyka czasowa jak i dokładność pomiaru mogą być regulowane przez właściwe ustawienie kontrolera PI i wzmacniacza Lock-In. Okazało się, że przy wzroście wzmocnienia proporcjonalnego, zmniejsza się zakres pomiarowy przy jednoczesnym zwiększeniu rozdzielczości. Metoda została zastosowana do wzorcowania niskotemperaturowego mikroskopu KFM. Osiągnięte wyniki potwierdzają, że KFM może mierzyć potencjał w zakresie -3...3 V. Obliczone odchylenie standardowe dla każdego punktu kalibracyjnego wynosiło mniej niż 15 mV. Biorąc pod uwagę także błąd systematyczny można skonkludować że niepewność w całym zakresie pomiarowym wynosi 20 mV.

EN

There are many possible ways to calibrate the Kelvin Probe Force Microscope [1] and various accuracy levels can be achieved accordingly to employed method. The paper presents novel method for calibrating Kelvin Probe Force Microscope. The method is based on measuring the surface potential of a reference sample and comparing it with the results obtained by KFM. It offers a calibration possibility in the whole measuring range of the microscope both in terms of absolute values and dynamic behavior. The surface potential of a reference sample used for calibration is adjusted according to needs (instead of being defined by physical parameters of the sample). Using this method both the time characteristics and the measurement accuracy can be adjusted by a proper setting of PI controller and Lock-In amplifier gains. In particular, with a higher proportional gain the measuring range is decreased but obtained resolution is increased. The method has been applied for the calibration of Unisoku Low Temperature KFM. Obtained results proves that KFM can measure the potential within the -3...3 V. The calculated standard deviation for each calibration point is less than 15 mV. Taking into consideration also systematic error it can be concluded, that the uncertainty in a whole measuring range is 20 mV.

6

Electrical Properties and Relaxation Behavior of TOPO Monolayers Formed at the Air/Water Interface

Wydro P., Hąc-Wydro K.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 1

115-127

EN

The properties of the Langmuir monolayer formed by tri-n-octylphosphine oxide (TOPO) have been analyzed. The investigations were based both on traditional (surface potential measurements) and more advanced (the relative reflectivity using Brewster angle microscopy BAM) experimental techniques and, for better analysis, the semiempirical computation using HyperChem programme has been done. Moreover, detailed characteristics of the relaxation behaviour of TOPO monolayers have been performed. It has been found that with the increase of the surface pressure () the film thickness increases, and TOPO monolayer becomes denser; however its state does not change. Upon film compression, the reorientation of TOPO molecules occurs in this way that they become progressively more perpendicular to the surface until the collapse of the monolayer. The relaxation of TOPO monolayers formed both on water subphase as well as on NaCl solution of various concentrations were analyzed according to two-steps desorption mechanism. As it turned out, the stability of TOPO monolayer decreases with the surface pressure. At lower the loss of the monolayer material is controlled both by dissolution and diffusion mechanism, while at higher surface pressure the monolayer relaxation is controlled by two dissolution steps of different rates and the monolayer does not achieve a steady-state. Moreover, the monolayer stability increases with ionic strength.

7

Insoluble Amphiphiles at the Air/Water Interface. The Characteristics of Alcohols Monolayers

Wydro P., Hąc-Wydro K., Paluch M.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 12

2041-2054

EN

In this paper thorough characteristics of monolayers formed at the air/water interface by two alcohols namely hexadecanol and octadecanol has been presented. The experiments were based on surface pressure/area and surface potential measurements. The visualization of monolayers has been performed using Brewster Angle Microscopy. It has been found that both alcohols form at the air/water interface condensed monolayers with transition between liquid condensed (LC) and solid (S) state. From the experimental results the thickness of monolayers has been calculated and compared with theoretical value. These calculations allow drawing conclusion of the slope of the hydrocarbon tails of investigated alcohols in monolayers. From the surface potential measurements the conformation of the O–H bond and the orientation of dipolemoments of both alcohols have been proposed. Moreover, the stability of monolayers formed by investigated alcohols has been studied and it has been found lower stability of hexadecanol monolayers in comparison with those formed by octadecanol.

8

Back Corona in Fabrics

Kacprzyk R., Miśta W.

Fibres & Textiles in Eastern Europe

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2006

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Vol. 14, no. 5 (59)

35--38

EN

This paper emphasises the practical aspect of the maximum surface potential of fabric. The phenomenon of back discharges (back corona) was described, and the possibility of generating these discharges on polymeric fabrics was practically confirmed. The results obtained showed that in the case of high volume-resistivity fabrics the back discharges may be the basic mechanism responsible for the limitation of the maximum value of the surface potential of fabrics placed on conducting surfaces. The limited application of Paschen’s law for determining the surface’s potential maximum value was also shown.

PL

W pracy zwrócono uwagę na aspekt praktyczny maksymalnego potencjału powierzchnio-wego tkanin, przedstawiono zjawisko wyładowań wstecznych i pokazano, na przykładzie tkanin polimerowych, możliwość jego występowania. Otrzymane wyniki wskazują, że w przypadku tkanin o wysokiej rezystywności skrośnej, wyładowania wsteczne mogą stanowić podstawowy mechanizm ograniczający maksymalną wartość potencjału powierzchniowego tkanin ułożonych na przewodzących powierzchniach. Stwierdzono ograniczoną przydatność prawa Paschen’a do oceny maksymalnej wartości potencjału powierzchniowego tkanin.

9

Comparative Studies of Film-Forming Properties of partially Fluorinated Tetracosanes

Broniatowski M., Miňones J., Sandez Macho I, Dynarowicz-Łątka P.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 6

1047-1061

EN

Contrary to simple n-alkanes of moderate molecular weight, which are not capable of Langmuir monolayer formation, partially fluorinated hydrocarbons of the general formula: F(CF2)m(CH2)nH (abbreviated as FmHn) were found to form monomolecular layers at the air/water interface. The aim of this study was to characterize several semifluorinated alkanes (SFA) containing 24 carbon atoms in total (tetracosanes) differing in the m/n ratio, as Langmuir monolayers at the free water surface. The following compounds have been investigated: F4H20, F6H18, F8H16, F10H14 and F12H12. Surface pressure (pi) and electric surface potential deltaV) isotherms were recorded in addition to quantitative Brewster angle microscopy results. The negative sign of deltaV evidenced for the orientation of all the semifluorinated tetracosanes investigated here, regardless the length of the hydrogenated segment, with their perfluorinated parts directed towards the air. As inferred from apparent dipole moment values and relative reflectivity results, tetracosanes with shorter perfluorinated fragment (F4H20 and F6H18) were found to take vertical orientation at the air/water interface, while those with longer perfluorinated moiety (F8H16, F10H14 and F12H12) remain tilted even in the vicinity of the film collapse. The observed differences may result from a different conformation of the perfluorinated chain, i.e. more fluorinated tetracosanes (F10H14 and F12H12) have their perfluorinated parts sufficiently long to form a helix, while less fluorinated derivatives (F4H20 and F6H18) may possibly exist in all-trans configuration. In particular, the perfluorinated fragment in F8H16 is considered to have an intermediate character between these two structures.

10

Surface potential distribution chart of DLC thin films

Lozovski T., Sakalauskas S., Dłużniewski M.

Karbo

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2005

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Nr 4

262-264

EN

Measuring system of the surface electric potential and its distribution is presented. The schematic instrument diagram is discussed. The surface potential distribution of thin carbon layers was investigated by the instrument. The relation of measured voltage with the sample physical parameters are discussed.

PL

Zaprezentowano ukiad do pomiaru powierzchniowego potencjału elektrycznego i jego rozkładu. Omówiono schemat przyrządu, za pomocą którego badano rozkład potencjału powierzchniowego cienkich warstw węglowych. Przedyskutowano związek zmierzonego napięcia z innymi fizycznymi parametrami próbki.

11

Perfluoroalkyl-n-eicosanes at the Air-Water Interface-A Monolayer Study

Broniatowski M., Dynarowicz-Łątka P.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 7

973-985

EN

Perfluoroalkyl-n-eicosanes of the general formula F(CF2)m(CH2)20H, where m = 4,6, 8,10,12 were spread at the air/water as Langmuir monolayers and studied at different experimental conditions, such as spreading volume, subphase temperature and compression speed. The Langmuir monolayer experiments (-A isotherms) have been complemented with quantitative Brewster angle microscopy results, which enabled estimation of the film thickness at different stages of compression. Although the investigated molecules do not possess any polar group and are purely hydrophobic, they form stable monomolecular layers at the free water surface. The negative sign of the measured surface potential, Delta V, evidences for the orientation of the molecules with their perfluorinated parts exposed towards the air, independently of the length of the perfluorinated moiety. The relative intensity measurements allow one to conclude that the molecules with shorter perfluorinated part (F4H20, F6H20 and F8H20) are oriented almost vertically (in respect to the interface) in the vicinity of film collapse, while F10H20 and F12H20 are tilted to the water surface.

12

Komputerowa symulacja rozkładu potencjałów powierzchniowych na potrzeby tomografii impedancyjnej

Nita D., Pałko T.

Elektronizacja : podzespoły i zastosowania elektroniki

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2003

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Vol. 23, nr 6

30-33

PL

Tomografia impedancyjna jest stosunkowo nową techniką obrazowania. Jej główną rolą jest rekonstrukcja rozkładu impedancji we wnętrzu badanego obiektu. Niniejsze opracowanie dotyczy zastosowania metody różnic skończonych do obliczania rozkładu napięcia na powierzchni obiektów jednorodnych i niejednorodnych oraz do wyznaczania wektorów pomiarowych zgodnych ze standardowym protokołem pomiarowym tomografii impedancyjnej. Przedstawiono przykładowe wyniki obliczeń otrzymane dla modeli obiektów w kształcie walca.

EN

Impedance tomography is quite new imaging technic. It's main role is to reconstruct the impedance distribution within the objects beeing in the scope of interest. This publication deals with the use of the Finite Difference Method for calculations of the electrical potentials on the surface of the homogenic and perturbated objects, as well, for the estimation of measurement vectors accordingly to the standard thomographic measurement protocol. Some examples of achieved results for models of cilindrical objects are shown.

13

ph Dependent Enantioselection of Amino Acids by Phosphorous-Containing Calix[4]resorcinarene in Langmuir Monolayers

Pietraszkiewicz M., Prus P., Bilewicz R.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 12

2035-2042

EN

Lipophilic calix[4]resorcinarene with phosphorous acid amide groups linking oxygen atoms is a rigid system of the cavitand type, in which conformational flexibility is strongly limited. These chiral receptors form stable Langmuir monolayers on water surface with surface area per molecule in the compressed layer being almost ph-independent.

14

pH Dependent Enantiomeric Recognition of Amino Acids by Mannich-Type Calix[4]resorcinarenes in Langmuir Monolayers

Pietraszkiewicz M., Prus P., Bilewicz R.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 11

1845-1853

EN

The surface potential of these compounds is distinctly higher in the presence of substituents and its further increase upon decreasing the pH of the subphase is observed only for the derivatized calixarenes. This means that protonation on the amine centers is the factor determining the properties of the monolayer.