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1

Are the phosphorus-rich Na2O–CaO–B2O3–SiO2–P2O5 glasses bioactive and what is an influence of doping with manganese oxide?

Bragiel P., Ficek P., Prochwicz W., Radkowska I., Veeraiah N.

Materials Science Poland

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2017

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Vol. 35, No. 4

760--766

EN

A series of glasses of the composition 20Na2-O-15CaO-5B2O3-5SiO2-(55 - x) P2O5:xMnO2, was prepared and characterized by XRD, DSC, SEM, and Raman techniques. The samples were later immersed in simulated body fluid (SBF) for checking the potential growth of hydroxyapatite layer (HA). Experiments confirmed that addition of manganese oxide leads to structural changes of the glasses. With increasing content of MnO2, the surface of the samples became more congenial for improving the growth of HA. The formation of HA layer on the surface of the samples was confirmed just after seven days of immersion. The growth rate of HA has gradually increased with the increase of MnO2 content.

2

Effect of surface coating with palladium on hydrogen permeability of Pd33Ni52Si15 amorphous alloy membrane

Prochwicz W., Macherzyński W., Paszkiewicz B., Stępień Z.

Optica Applicata

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2016

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Vol. 46, nr 2

173--179

EN

In the paper, the effect of the surface coating with palladium on hydrogen permeation of a Pd33Ni52Si15 amorphous alloy membrane was investigated. We have measured the hydrogen flow through the melt-spun amorphous membrane covered with palladium film of 10, 20, and 30 nm in thickness. Membranes have been tested in the temperature rage 294–358 K, and at pressure fixed at 102 kPa. We investigate the role of this film thickness on the activation energy for hydrogen permeability. It seemed that a relatively thin layer of the palladium on the surface of the membrane which contains over 30% of this element, should not considerably influence the permeability of the membrane for hydrogen. The membrane hydrogen permeability is correlated to permeation activation energy: the lower activation energy is, the higher permeability is observed. The activation energy for permeation strongly depends on palladium film thickness. The rapid increase of its value was recorded when the film thickness was growing up. As the result, the increase of the film thickness suppressed hydrogen permeability. Our findings are discussed in terms of a potential barrier between the two different phases.

3

Hydrogen permeation properties of Pd-coated Pd33Ni52Si15 amorphous alloy membrane

Prochwicz W., Macherzyński W., Paszkiewicz B., Stępień Z. M.

Materials Science Poland

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2015

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Vol. 33, No. 1

56--58

EN

The vast majority of experimental techniques used for the measurements of hydrogen permeability through metallic membranes whose one or both surfaces are covered with a thin Pd film is based on the assumption that a ratio of film-to-membrane thickness is small enough to cause hydrogen flow to be independent of the Pd film thickness. In an attempt to verify this assumption, we have measured the hydrogen flow through the Pd33Ni52Si15 amorphous membrane covered with Pd film of 10, 20, and 30 nm in thickness. Contrary to our expectations, we have found a dramatic decrease in hydrogen flow with the increase in Pd film thickness. Our findings are discussed in terms of potential barrier between the two different phases.

4

Degradacja hydrolityczna rusztowań komórkowych formowanych z terpolimerów; L-laktydu, glikolidu i TMC, oraz L-laktydu, glikolidu i ε-kaprolaktonu

Kot M., Wawryło L., Rychter P., Prochwicz W., Smola A., Dobrzyński P.

Engineering of Biomaterials

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2015

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Vol. 18, no. 130

10--19

PL

Głównym celem prezentowanej pracy było zbadanie przebiegu degradacji hydrolitycznej porowatych rusztowań komórkowych wykonanych z bioresorbowalnych terpolimerów z pamięcią kształtu; L-laktydu, glikolidu i węglanu trimetylenu, oraz L-laktydu, glikolidu i ε-kaprolaktonu. W trakcie prowadzonej hydrolizy odnotowywano spadki masy i średnich mas cząsteczkowych, oraz niewielkie zmiany chłonności wody badanych materiałów. Za pomocą mikroskopii skaningowej (SEM) śledzono zmiany morfologii powierzchni rusztowań zachodzące podczas prowadzonej degradacji in vitro. Przeprowadzone badania wykazały, że podłoża komórkowe formowane z terpolimerów L-LA/GA/ o-TMC i L-LA/GA/ε-CL ulegają stopniowej degradacji hydrolitycznej, a udział enzymu – lipazy wyraźnie przyspieszał ten proces zwłaszcza w wypadku rusztowania formowanego z kopolimeru zawierającego mikrobloki węglanowe. Najniższy ubytek masy odnotowano dla próbki zawierającej jednostki węglanowe, wynosił on około 10% masy wyjściowej rusztowań po 112 dniach, a w wypadku obecności lipazy masa tego materiału była niższa o ponad 24%. Wysoki stopień porowatości otrzymanych rusztowań, a co za tym idzie ich duża powierzchnia właściwa powoduje, że materiały te podatne są w znacznie większym stopniu na degradację enzymatyczną, niż podobne lite materiały wykonane z tych samych terpolimerów. Spadek liczbowo średniej masy cząsteczkowej był obserwowany w przypadku obu rodzajów terpolimerów, jednak dla terpolimeru z jednostkami kaproilowymi był on wyraźnie większy (po 112 dniach z około 40 tys. g/mol do około 2 tys. g/ mol). Warte uwagi jest to, że stopień degradacji próbek wykonanych z terpolimeru L-LA/GA/o-TMC, podczas trzech pierwszych tygodni, był stosunkowo mały, a dopiero wyraźne silne przyspieszenie tego procesu nastąpiło po 30 dniach. W przypadku degradacji prowadzonej w obecności lipazy zanotowano w czasie 112 dni spadek liczbowo średniej masy cząsteczkowej tego materiału z około 40 tys. g/mol do 9 tys. g/mol. Z punktu widzenia inżynierii tkankowej powolny proces degradacji terpolimeru L-LA/GA/o-TMC w ciągu pierwszych dwóch - trzech tygodni jest bardzo korzystny, ponieważ komórki mają wystarczająco dużo czasu na migrację, adhezję i namnażanie.

EN

The main aim of this work was to check the degradation course of polymeric scaffolds in medium with and without of enzyme - pancreatic lipase. Based on the conducted degradation studies the usefulness of the formed scaffolds was confirmed. Scaffolds have been prepared using two types of terpolymers varying in composition: L-lactide, glycolide, trimethylene carbonate, and L-lactide, glycolide and ε-caprolactone. The weight loss, water absorption, molecular weight distribution (by GPC) as well as changes in surface morphology using SEM during degradation process have been evaluated. The results have proved the degradation process of scaffolds, both in the hydrolytic and enzymatic ways has been occurred. Addition of an enzyme - lipase facilitates the degradation process of the samples, especially those containing carbonate segments. High porosity of the scaffolds and their huge specific surface area make these materials more susceptible to degradation as compared to solid materials i.e. blown, extruded polymers. Decrease in the number average molecular weight was observed in the case of both degraded scaffolds; however in that containing caproyl units it was higher. It is worth noting, that degradation rate of sample L-LA/GA/o-TMC during first three weeks is quite slow showing almost the same behaviour for both enzymatic and hydrolytic degradation. From the tissue engineering point of view the slow degradation process of the terpolymer L-LA/GA/o-TMC during first two - three weeks is very promising because cells would have enough time for migration, adhesion and proliferation.

5

Electrical conductivity of Pd47Ni47Si6 amorphous membrane while hydrogen permeation

Prochwicz W., Stępień Z.M.

Materials Science Poland

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2013

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Vol. 31, No. 4

484--488

EN

Hydrogen diffusion through an amorphous membrane causes local disorders in the structure which can be detected through the measurement of changes of the electrical conductivity. Detecting these changes and comparing them directly with the amount of the permeated hydrogen provides information on the efficiency of separation, which can be used in hydrogen sensor and analyzer technology. This paper presents the results of electrical resistivity measurement of Pd47Ni47Si6 alloy amorphous membrane while hydrogen permeation flux was being changed along with the temperature. It was found that hydrogen changes the nature of the resistivity and the temperature coefficient of resistivity is negative, however, starting from the temperature of 365 K, its value becomes smaller. In order to explain this phenomenon thorough and detailed measurements of phase transitions were made with the use of differential scanning calorimetry and X-ray diffractometry. On the basis of the research an attempt was made to explain the recorded changes of electrical conductivity.

6

Electric current stimulation of hydrogen diffusion through an amorphous palladium membrane

Prochwicz W., Kolano R., Stepień Z.

Optica Applicata

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2009

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Vol. 39, nr 4

799-805

EN

The work presents the results of the diffusion of hydrogen through a membrane made of amorphous palladium alloy in which one of the surfaces was modified with a layer of carbon nanotubes. We used an amorphous membrane made with a single roller spinning technique. The measurements were performed at ambient temperature. In this work, an attempt was made to study the impact of the flow of electric charge on the diffusion of hydrogen through thus modified amorphous palladium alloy membrane.

7

Model of ageing process of electroluminescent structures

Porada Z., Cież M., Prochwicz W.

Materiały Elektroniczne

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2009

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T. 37, nr 1

117-123

EN

In the presented paper the authors propose a new mathematical model of aging process proceeded in thick film electroluminescent structures. The impact of humidity, temperature and supply voltage parameters (amplitude, frequency) on luminance changes during long time exploitation tests was taken into consideration. It was observed that the electroluminophore in Destriau electroluminescent cells exhibit very fast decrease in luminance in the initial phase of exploitation. The results of investigations indicate that the increase of amplitude and frequency of supply voltage accelerate the aging process. The rate of the aging process is also significantly influenced by the ambient temperature and elevated humidity combined with a supply voltage. The proposed model enables to estimate the life-time of electroluminescent structures on a base of exploitation tests in their initial stage.

PL

Autorzy proponują w artykule nowy matematyczny model procesu starzenia zachodzącego w grubowarstwowych strukturach elektroluminescencyjnych. Uwzględniono wpływ wilgoci, temperatury i parametrów napięcia zasilającego (amplituda, częstotliwość) na zmiany luminancji podczas prób eksploatacyjnych. Zaobserwowano, że w początkowej fazie eksploatacji elektroluminofor w strukturach Destriau - warstwowych strukturach elektroluminescencyjnych, bardzo szybko zmniejsza luminancję. Wyniki badań wskazują, że wzrost wielkości amplitudy napięcia zasilającego i częstotliwości przyspiesza proces starzenia. Szybkość procesu starzenia struktur elektroluminescencyjnych w istotny sposób zależy od temperatury otoczenia i podwyższonej wilgotności w powiązaniu z napięciem zasilania. Zaproponowany model umożliwia oszacowanie czasu życia struktur elektroluminescencyjnych w oparciu o wyniki badań eksploatacyjnych, już w początkowej ich fazie.

8

The solid solutions in the Zr-Zn-Ni System at 600°C

Dolotko O., Prochwicz W.

Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie

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2001

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Vol. 5

9--14