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1
Content available remote Elektroanaliza parabenów w kosmetykach
Michałkiewicz S., Jakubczyk M.
Przemysł Chemiczny
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2017
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T. 96, nr 6
1394--1397
PL
Opracowano nową, prostą oraz szybką woltamperometryczną metodę oznaczania parabenów w kosmetykach z zastosowaniem techniki pulsowej różnicowej DPV (differential pulse voltammetry) na mikroelektrodzie z włókna węglowego o średnicy 35,4 μm. Środowiskiem do badań była mieszanina lodowatego kwasu octowego i acetonitrylu (20% obj.) zawierająca 0,1 M octan sodu jako elektrolit podstawowy. Taki skład roztworu umożliwia oznaczanie tych konserwantów nawet w obecności matryc. Uzyskano zadowalające co do precyzji oraz dokładności wyniki oznaczania. Opracowana metoda może być skutecznym narzędziem do kontroli zawartości parabenów w analizach laboratoryjnych przemysłu kosmetycznego.
EN
Total content of parabens was detd. by differential pulse voltammetry (DPV) with C fiber microelectrode. The measurements were carried out in a mixt. of glacial AcOH and MeCN (20% by vol.) contg. 0.1 M AcONa. A good accuracy of the DPV method was achieved and its usefulness in routine anal. under industrial conditions was confirmed.
2
Content available Analiza przyczyn uszkodzenia stropu
Jakubczyk M., Trochimiak I., Szydłowski R.
Builder
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2017
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R.21, nr 8
88--90
EN
Analysis ol the cause of damage of a reinforced concrete floor above a garage of a multi-storey residential building. Undertaking an accurate assessment of the effects of concrete shrinkage and required minimum shrinkage reinforcement of complex reinforced concrete constructions emphasizes the fact of being an exceedingly difficult issue to consider. The analysis below broaches this matter basing on the example of a fragment of a building characterized by a rare construction system. Since the shrinkage aspects have not been taken into account, the applied reinforcement concerns only bending. Indeed, this fact, as well as the peculiarity of a shape of the building, affected the ceiling surface causing the emergence of a crack across its length and thus, plenty of leaks. The study of the above-mentioned case attempts to specify the quantity of required reinforcement by comparing results obtained from various methods adopted for this purpose.
3
Content available remote Woltamperometryczna identyfikacja i oznaczanie antyutleniaczy syntetycznych w olejach roślinnych
Michalkiewicz S., Jakubczyk M.
Przemysł Chemiczny
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2016
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T. 95, nr 1
98--102
PL
Opracowano prostą, szybką i bezpieczną dla środowiska woltamperometryczną metodę identyfikacji i oznaczania antyutleniaczy syntetycznych TBHQ, BHA oraz BHT w olejach roślinnych z zastosowaniem techniki pulsowej różnicowej (DPV) na mikroelektrodzie Pt o średnicy 50 μm. Środowiskiem do badań była mieszanina lodowatego kwasu octowego i octanu etylu (3:2, obj.) zawierająca 0,1 M chloran(VII) sodu jako elektrolit podstawowy. Takie środowisko umożliwia identyfikację tych antyutleniaczy w obecności naturalnych matryc. Ze względu na interferencje sygnałów pochodzących od tokoferoli i TBHQ, analiza ilościowa jest możliwa jedynie dla BHA i BHT. W analizowanych olejach stwierdzono obecność tylko BHT i uzyskano zadowalające co do precyzji oraz dokładności wyniki jego oznaczania. Opracowana metoda może być skutecznym narzędziem do kontroli zawartości antyutleniaczy syntetycznych w analizach laboratoryjnych w przemyśle spożywczym.
EN
Contents of 3-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxytoluene and 2-tert-butyl-4-hydroxyphenol antioxidants in rapeseed, sunflower, corn, linseed and olive oils were detd. by differential pulse voltammetry at a Pt microelectrode (50 μm diam.) in a mixt. of glacial AcOH and EtOAc (3:2 by vol.) with 0.1 M NaClO4. The method was recommended as an effective tool to control the content of synthetic antioxidants in the vegetable oils.
4
Content available remote Crystallization kinetics of Fe78Si9B13 metallic glass
Jakubczyk E., Krajczyk L., Siemion P., Jakubczyk M.
Optica Applicata
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2007
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Vol. 37, nr 4
359-370
EN
The investigation of Fe78Si9B13 metallic glass was carried out by means of non- isothermal DSC and X-ray diffraction methods. Two crystalline phases: ?-Fe(Si) and (Fe,Si)2B were identified during the crystallization process. Based on the Kissinger equation the activation energies for both phases were calculated. Using the Gao equation the Avrami kinetics exponent was determined. TEM studies proved the creation of these phases and also showed the presence of the FeB49 phase in the remaining amorphous phase.
5
Content available remote Morphology and the kinetics of the crystal growth
Jakubczyk M., Kopyciak G.
Prace Naukowe. Chemia i Ochrona Środowiska / Akademia im. Jana Długosza w Częstochowie
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2005
|
Vol. 10
59--63
6
Content available remote Changes of properties of Co66Ni12Si9B13 metallic glass in process devitryfication
Jakubczyk E., Jakubczyk M., Kapuśniak J.
Prace Naukowe. Chemia i Ochrona Środowiska / Akademia im. Jana Długosza w Częstochowie
|
2005
|
Vol. 10
149--156
EN
Isochronal annealing during 4h at different temperatures (573 ÷ 823 K) of samples of Co66Ni12Si9B13 metallic glass leads to the creation in the amorphous matrix three crystalline phases, i.e. at the temperature 673K phases α -(Co,Ni) and at the temperature 773K phase (Co,Ni)3B and (Co,Ni)2B. The result of the applied thermal treatment of the samples was their complete crystallization. The process of the annealing of the alloy leads to the systematic decrease of the electrical resistivity, Hall resistivity and the spontaneous Hall coefficient, and the creation of the crystalline phase is related to abrupt value decrease of these parameters. The calculations by quantum chemistry method confirm sequence and verify the composition of the created phases. The growth of gram sice of formed phases were observed by the optical microscope.
7
Content available remote Influence of the composition of M78Si9B13 metallic glasses on their structural stability
Jakubczyk E., Stępień Z., Jakubczyk M.
Optica Applicata
|
2005
|
Vol. 35, nr 3
339-346
EN
The structural stability of Co78Si9B13 and Fe78Si9B13 metallic glasses was investigated by differential scanning calorimetry (DSC), X-ray diffraction, Hall effect and electrical resistivity methods. It was found that at first isochronal annealing leads to the formation of a(alfa)-M (M = Co, Fe) phases.This process is followed by the formation of M2B phases. The phases were identified by X-ray diffraction method and their structures were confirmed with the use of quantum chemistry method. The creation of crystalline phases decreases abruptly the Hall and electrical resistivities. The alloy containing Fe appeared to have a much wider range of structural stability.
8
Kinetics of the crystal growth from the solution
Jakubczyk M., Kopyciak G., Frej H.
Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie
|
2003
|
Vol. 8
149--153
9
Evolution of properties of CO66NI12Sl9B13 metallic glass induced by isochrona annealing
Jakubczyk E., Jakubczyk M.
Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie
|
2003
|
Vol. 8
141--148
10
Content available remote Changes of properties during the annealing Fe28Co50Si9B13 and Fe28Ni50Si9B13 metallic glasses
Jakubczyk E., Jakubczyk M.
Optica Applicata
|
2002
|
Vol. 32, nr 3
241-246
EN
The crystallization of Fe28Co50Si9B13 and Fe28Ni50Si9B13 metallic glasses was stimulated by isochronal annealing at the temperature of 573–823 K, and was investigated by measuring the electrical resistivity, Hall effect and X-ray diffraction. The substitution of Co by Ni has proved the differences in the initial and final parameters, as well as in the kinetics of crystallization. The creation of crystalline phases from the amorphous matrix was related to the abrupt decrease in the electrical and Hall resistivities, and in the spontaneous Hall coefficient.
11
Influence of hydrodynamics on kinetics of crystal growth
Jakubczyk M., Kopyciak G.
Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie
|
2001
|
Vol. 5
21--26
12
A kinetic theory of crystal growth from aqueous solutions
Jakubczyk M.
Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie
|
2001
|
Vol. 5
15--19
EN
The process of the crystal growth kinetics was investigated using the Fokker-Planck equation. The use of the diffusion Fick equation to relate the surface concentration and diffusion requires the use of the modified surface diffusion coefficient which is D = Ds( 1+o(β) where: Ds - is a diffusion coefficient witch the absence of adsorption and desorption, β =1/ξTD is a ratio of relation time characterizing the diffusion surface (1/β)and desorption TD.
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