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Zeitschriftendaten
Format
Zeitschrift
eISSN
1899-4741
Erstveröffentlichung
03 Jul 2007
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 21 (2019): Heft 2 (June 2019)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1899-4741
Erstveröffentlichung
03 Jul 2007
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

10 Artikel
access type Uneingeschränkter Zugang

Numerical analysis of stress distribution generated in spherical polyethylene inserts by knee joint endoprotheses’ sleds

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 1 - 5

Zusammenfassung

Abstract

The paper presents analysis of stress distribution in the friction node of knee joint endoprosthesis where sleds are made of various titanium alloys and CoCrMo cooperate with spherical polyethylene inserts. Currently used titanium alloys consists of Nb, Ta, Zr or Mo and with lesser value of Young’s modulus than Ti6Al4V alloy, or steel CoCrMo, which significantly varies from other metal materials. The obtained results make it possible to indicate the “weak points” of the accepted solution, and thus counteract the subsequent effects resulting from premature wear of endoprosthesis elements. The analysis was conducted with numerical method of ADINA System 8.6. The Finite Elements Method allowed to compute and present stress distribution quickly in all elements of the model.

Schlüsselwörter

  • polyethylene UHMWPE
  • FEM
  • endoprosthesis of knee joint
access type Uneingeschränkter Zugang

Silver nanoparticles deposited on calcium hydrogenphosphate – silver phosphate matrix; biological activity of the composite

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 6 - 13

Zusammenfassung

Abstract

The composite containing nanosilver uniformly deposited on matrix composed of CaHPO4 x 2H2O (brushite, ca 89 mass %), CaHPO4 (monteonite, ca 9.5 mass%), and Ag3PO4 (0.5 mas%) was obtained by addition of calcium nitrate and silver nitrate aqueous solution at 30:1 Ca:Ag molar ratio into excess of (NH4)2PO4 solution at pH 5.0 – 5.5. The isolated solid was characterized by STEM, XRD, and LDI mass spectrometry. It has been found that nanosilver was uniformly distributed within composite as <10 nm diameter sized nanoparticles. Determination of silver by AAS showed that 60% of silver is present as Ag(0) nanoparticles, the present as matrix Ag3PO4 as identified by XRD method. The composite showed strong growth inhibition in E. coli and P. aeruginosa strains, and moderate towards S. aureus. The C. albicans cells were the most resistant to the tested material, although still composite was moderately cytostatic for the yeast.

Schlüsselwörter

  • silver nanoparticles
  • composite
  • calcium hydrogenphosphate matrix
  • electron microscopy
  • mass spectrometry
access type Uneingeschränkter Zugang

Removal of Hexavalent Chromium from Aqueous Solution by the Pod of Acacia gerrardii

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 14 - 19

Zusammenfassung

Abstract

This study aims at investigating the potential of Acacia gerrardii pod for the removal of Cr(VI) in batch system. Effect of solution pH, biosorbent dosage, initial concentration of Cr(VI), contact time on the removal process was examined. Complete removal of hexavalent chromium was achieved at pH values 1.0 and 2.0 whereas maximum removal of total chromium was obtained at pH of 3.0. The study showed that the biosorption and bioreduction mechanisms were involved in the removal process. The time required for complete removal of Cr(VI) using the pod of Acacia gerrardii was shortened with an increase in biomaterial dosage and decrease in Cr(VI) concentration. Kinetic data was well described using Park kinetic model. Freundlich isotherm model adequately fitted the equilibrium data indication multilayer adsorption of total chromium on the surface of biomaterial. The pod of Acacia gerrardii could be used efficiently for the removal of hexavalent chromium from aqueous solutions.

Schlüsselwörter

  • Biosorption
  • chromium
  • isotherm models
  • Park kinetic models
access type Uneingeschränkter Zugang

The effect of ash and compost on the content and bioaccumulation of selected heavy metals

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 20 - 25

Zusammenfassung

Abstract

Therefore the carried out study aimed at determination of the effect of high-calcium brown coal ash and compost being produced from municipal sewage sludge on the content and bioaccumulation of heavy metals in potato tubers, wheat grains and rapeseeds during a three-year period. Rapeseeds contained most Cd whereas wheat rains less. Potato tubers, wheat grains and rapeseeds contained more Mn, Ni and Zn in the fertilization objects with municipal sewage sludge with or without coal ash and compared to those where calcium carbonate or coal ash had been introduced into the soil at a dose corresponding to 1.5 Mg CaO · ha–1 at the beginning of this study. Differences in the Mn, Ni and Zn contents in test plants between the fertilization objects with sewage sludge of with and without addition of ash were not significant.

Schlüsselwörter

  • ash
  • compost
  • heavy metals
  • bioaccumulation
  • test plants
access type Uneingeschränkter Zugang

Hydrophilic films based on starch and carboxymethyl starch

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 26 - 30

Zusammenfassung

Abstract

The hydrophilic films based on starch and carboxymethyl starch (CMS) were obtained using cast method. The effect of CMS content on the physicochemical properties of prepared films were evaluated. With increasing content of starch derivative the moisture absorption, solubility in water as well as swelling ratio increased. The highest values of mechanical parameters (tensile strength and Young’s modulus) were determined for the starch/CMS film containing the lowest CMS amount, i.e. 10 wt.% (1.1 MPa, 15 MPa, respectively). For the same system the lowest moisture absorption, solubility in water as well as swelling ratio were reported. Thus, it could be concluded that for this system the highest crosslinking density has been achieved, what was confirmed by DMTA results. Such a film could potentially find application in food or agricultural industry.

Schlüsselwörter

  • carboxymethyl starch
  • hydrophilic films
  • polysaccharide films
  • starch
access type Uneingeschränkter Zugang

Dry and steam reforming of methane. Comparison and analysis of recently investigated catalytic materials. A short review.

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 31 - 37

Zusammenfassung

Abstract

In order to produce valuable syngas, industrial processes of dry reforming of methane and steam reforming of methane must be further developed. This paper is focused on reviewing recently examined catalysts, supporting the mentioned technologies. In both processes the most popular active material choice is usually nickel, due to its good availability. On the other hand, noble metals, such as ruthenium, rhodium or platinum, provide better performance, however the solution is not cost-effective. Materials used as a support influence the catalytic activity. Oxides with basic properties, such as MgO, Al2O3, CeO2, are frequently used as carriers. One of the most promising materials for reforming of methane technologies are hydrotalcites, due to adjustable composition, acid-base properties and possibility of incorporation of various metals and complexes.

Schlüsselwörter

  • dry methane reforming
  • steam methane reforming
  • nickel catalyst
  • hydrotalcite
access type Uneingeschränkter Zugang

Comparison of the composition and fungicidal activity of essential oils from fennel fruits cultivated in Poland and Egypt

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 38 - 42

Zusammenfassung

Abstract

The yield, composition and fungicidal activity of essential oils obtained from fennel fruits cultivated in Poland (FEOPOL) and Egypt (FEO-EG) were compared. The influence of the duration of hydrodistillation using a Clevenger apparatus on the essential oil yield was studied. The composition of the fennel essential oils was determined by GC-MS method. Studies have shown that FEO-POL and FEO-EG are two distinct chemotypes, which differ in yield and composition. The fennel fruits cultivated in Poland contained 4.14% of essential oil with trans-anethole as a main component. The plant material from Egypt was characterised by low content of essential oil (1.32%) with a predominant share of estragole. The fungicidal activity was tested in vitro against ten species of pathogenic fungi. The best result for FEO-POL was achieved against Sclerotinia sclerotiorum, Rhizoctonia solani and Botrytis cinerea. Antifungal activity of FEO-EG against tested fungi was weak or none.

Schlüsselwörter

  • fennel essential oil
  • Mill.
  • fungicidal activity
  • -anethole
  • estragole
access type Uneingeschränkter Zugang

Effects of the type of biomass and ashing temperature on the properties of solid fuel ashes

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 43 - 51

Zusammenfassung

Abstract

Ashes were prepared by annealing selected types of solid fuels (biomass: corn cobs, sunflower husks, olive pomace, hay pellets and rice husks; coal: lignite and bituminous; and alternative fuel: paper sludge) at different temperatures (550°C, 815°C and 975°C). Based on X-ray fluorescence spectra, the slagging/fouling indexes were used to study the effects of the type of ash and the ashing temperature on the ash fouling and slagging properties. Slagging indexes were compared with the ash fusion temperatures. Ash fusion temperatures were measured by a LECO AF-700. The lowest deformation temperature (below 1000°C) was seen for the ashes prepared from hay pellets and corn cobs. On the other hand, the deformation temperature exceeded 1500°C for ashes prepared from paper sludge, sunflower husks and rice husks. By calculating the different slagging/fouling indexes, all the ashes exhibited slagging/fouling problems of varying degrees.

Schlüsselwörter

  • biomass
  • ashing temperature
  • ash fusion temperature
  • slagging index
  • fouling index
access type Uneingeschränkter Zugang

Strontium-based nanosized phosphates as anticorrosive fillers of epoxy and polyurethane coating compositions

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 52 - 58

Zusammenfassung

Abstract

Anticorrosive epoxy and polyurethane coatings were compounded using zinc-free nanosized phosphates of strontium (SP) or strontium and aluminum (SAP). For comparison, a nanosized calcium aluminum ammonium phosphate (CAP) and a microsized zinc phosphate (ZP) were tested. Results of salts spray and cyclic corrosion tests revealed better anticorrosive properties of the SAP-based coatings in relation to the samples with the other Zn-free fillers or ZP. Electrochemical noise tests of uncoated steel in aqueous suspensions of the phosphates exhibited similar corrosion inhibition efficiency of the Sr-based phosphates and ZP, and worse anticorrosive features of CAP. Electrochemical impedance spectroscopy did not show better protective properties of ZP-based coatings than the samples with the Zn-free fillers.

Schlüsselwörter

  • Strontium phosphate
  • strontium aluminum phosphate
  • calcium aluminum ammonium phosphate
  • zinc phosphate
  • anticorrosive coatings
access type Uneingeschränkter Zugang

Immobilization of permeabilized cells of baker’s yeast for decomposition of H2O2 by catalase

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 59 - 63

Zusammenfassung

Abstract

Permeabilization is one of the effective tools, used to increase the accessibility of intracellular enzymes. Immobilization is one of the best approaches to reuse the enzyme. Present investigation use both techniques to obtain a biocatalyst with high catalase activity. At the beginning the isopropyl alcohol was used to permeabilize cells of baker’s yeast in order to maximize the catalase activity within the treated cells. Afterwards the permeabilized cells were immobilized in calcium alginate beads and this biocatalyst was used for the degradation of hydrogen peroxide to oxygen and water. The optimal sodium alginate concentration and cell mass concentration for immobilization process were determined. The temperature and pH for maximum decomposition of hydrogen peroxide were assigned and are 20°C and 7 respectively. Prepared biocatalyst allowed 3.35-times faster decomposition as compared to alginate beads with non permeabilized cells. The immobilized biocatalyst lost ca. 30% activity after ten cycles of repeated use in batch operations. Each cycles duration was 10 minutes. Permeabilization and subsequent immobilization of the yeast cells allowed them to be transformed into biocatalysts with an enhanced catalase activity, which can be successfully used to decompose hydrogen peroxide.

Schlüsselwörter

  • cell permeabilization
  • baker’s yeast
  • hydrogen peroxide
  • immobilization
  • biocatalyst
10 Artikel
access type Uneingeschränkter Zugang

Numerical analysis of stress distribution generated in spherical polyethylene inserts by knee joint endoprotheses’ sleds

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 1 - 5

Zusammenfassung

Abstract

The paper presents analysis of stress distribution in the friction node of knee joint endoprosthesis where sleds are made of various titanium alloys and CoCrMo cooperate with spherical polyethylene inserts. Currently used titanium alloys consists of Nb, Ta, Zr or Mo and with lesser value of Young’s modulus than Ti6Al4V alloy, or steel CoCrMo, which significantly varies from other metal materials. The obtained results make it possible to indicate the “weak points” of the accepted solution, and thus counteract the subsequent effects resulting from premature wear of endoprosthesis elements. The analysis was conducted with numerical method of ADINA System 8.6. The Finite Elements Method allowed to compute and present stress distribution quickly in all elements of the model.

Schlüsselwörter

  • polyethylene UHMWPE
  • FEM
  • endoprosthesis of knee joint
access type Uneingeschränkter Zugang

Silver nanoparticles deposited on calcium hydrogenphosphate – silver phosphate matrix; biological activity of the composite

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 6 - 13

Zusammenfassung

Abstract

The composite containing nanosilver uniformly deposited on matrix composed of CaHPO4 x 2H2O (brushite, ca 89 mass %), CaHPO4 (monteonite, ca 9.5 mass%), and Ag3PO4 (0.5 mas%) was obtained by addition of calcium nitrate and silver nitrate aqueous solution at 30:1 Ca:Ag molar ratio into excess of (NH4)2PO4 solution at pH 5.0 – 5.5. The isolated solid was characterized by STEM, XRD, and LDI mass spectrometry. It has been found that nanosilver was uniformly distributed within composite as <10 nm diameter sized nanoparticles. Determination of silver by AAS showed that 60% of silver is present as Ag(0) nanoparticles, the present as matrix Ag3PO4 as identified by XRD method. The composite showed strong growth inhibition in E. coli and P. aeruginosa strains, and moderate towards S. aureus. The C. albicans cells were the most resistant to the tested material, although still composite was moderately cytostatic for the yeast.

Schlüsselwörter

  • silver nanoparticles
  • composite
  • calcium hydrogenphosphate matrix
  • electron microscopy
  • mass spectrometry
access type Uneingeschränkter Zugang

Removal of Hexavalent Chromium from Aqueous Solution by the Pod of Acacia gerrardii

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 14 - 19

Zusammenfassung

Abstract

This study aims at investigating the potential of Acacia gerrardii pod for the removal of Cr(VI) in batch system. Effect of solution pH, biosorbent dosage, initial concentration of Cr(VI), contact time on the removal process was examined. Complete removal of hexavalent chromium was achieved at pH values 1.0 and 2.0 whereas maximum removal of total chromium was obtained at pH of 3.0. The study showed that the biosorption and bioreduction mechanisms were involved in the removal process. The time required for complete removal of Cr(VI) using the pod of Acacia gerrardii was shortened with an increase in biomaterial dosage and decrease in Cr(VI) concentration. Kinetic data was well described using Park kinetic model. Freundlich isotherm model adequately fitted the equilibrium data indication multilayer adsorption of total chromium on the surface of biomaterial. The pod of Acacia gerrardii could be used efficiently for the removal of hexavalent chromium from aqueous solutions.

Schlüsselwörter

  • Biosorption
  • chromium
  • isotherm models
  • Park kinetic models
access type Uneingeschränkter Zugang

The effect of ash and compost on the content and bioaccumulation of selected heavy metals

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 20 - 25

Zusammenfassung

Abstract

Therefore the carried out study aimed at determination of the effect of high-calcium brown coal ash and compost being produced from municipal sewage sludge on the content and bioaccumulation of heavy metals in potato tubers, wheat grains and rapeseeds during a three-year period. Rapeseeds contained most Cd whereas wheat rains less. Potato tubers, wheat grains and rapeseeds contained more Mn, Ni and Zn in the fertilization objects with municipal sewage sludge with or without coal ash and compared to those where calcium carbonate or coal ash had been introduced into the soil at a dose corresponding to 1.5 Mg CaO · ha–1 at the beginning of this study. Differences in the Mn, Ni and Zn contents in test plants between the fertilization objects with sewage sludge of with and without addition of ash were not significant.

Schlüsselwörter

  • ash
  • compost
  • heavy metals
  • bioaccumulation
  • test plants
access type Uneingeschränkter Zugang

Hydrophilic films based on starch and carboxymethyl starch

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 26 - 30

Zusammenfassung

Abstract

The hydrophilic films based on starch and carboxymethyl starch (CMS) were obtained using cast method. The effect of CMS content on the physicochemical properties of prepared films were evaluated. With increasing content of starch derivative the moisture absorption, solubility in water as well as swelling ratio increased. The highest values of mechanical parameters (tensile strength and Young’s modulus) were determined for the starch/CMS film containing the lowest CMS amount, i.e. 10 wt.% (1.1 MPa, 15 MPa, respectively). For the same system the lowest moisture absorption, solubility in water as well as swelling ratio were reported. Thus, it could be concluded that for this system the highest crosslinking density has been achieved, what was confirmed by DMTA results. Such a film could potentially find application in food or agricultural industry.

Schlüsselwörter

  • carboxymethyl starch
  • hydrophilic films
  • polysaccharide films
  • starch
access type Uneingeschränkter Zugang

Dry and steam reforming of methane. Comparison and analysis of recently investigated catalytic materials. A short review.

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 31 - 37

Zusammenfassung

Abstract

In order to produce valuable syngas, industrial processes of dry reforming of methane and steam reforming of methane must be further developed. This paper is focused on reviewing recently examined catalysts, supporting the mentioned technologies. In both processes the most popular active material choice is usually nickel, due to its good availability. On the other hand, noble metals, such as ruthenium, rhodium or platinum, provide better performance, however the solution is not cost-effective. Materials used as a support influence the catalytic activity. Oxides with basic properties, such as MgO, Al2O3, CeO2, are frequently used as carriers. One of the most promising materials for reforming of methane technologies are hydrotalcites, due to adjustable composition, acid-base properties and possibility of incorporation of various metals and complexes.

Schlüsselwörter

  • dry methane reforming
  • steam methane reforming
  • nickel catalyst
  • hydrotalcite
access type Uneingeschränkter Zugang

Comparison of the composition and fungicidal activity of essential oils from fennel fruits cultivated in Poland and Egypt

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 38 - 42

Zusammenfassung

Abstract

The yield, composition and fungicidal activity of essential oils obtained from fennel fruits cultivated in Poland (FEOPOL) and Egypt (FEO-EG) were compared. The influence of the duration of hydrodistillation using a Clevenger apparatus on the essential oil yield was studied. The composition of the fennel essential oils was determined by GC-MS method. Studies have shown that FEO-POL and FEO-EG are two distinct chemotypes, which differ in yield and composition. The fennel fruits cultivated in Poland contained 4.14% of essential oil with trans-anethole as a main component. The plant material from Egypt was characterised by low content of essential oil (1.32%) with a predominant share of estragole. The fungicidal activity was tested in vitro against ten species of pathogenic fungi. The best result for FEO-POL was achieved against Sclerotinia sclerotiorum, Rhizoctonia solani and Botrytis cinerea. Antifungal activity of FEO-EG against tested fungi was weak or none.

Schlüsselwörter

  • fennel essential oil
  • Mill.
  • fungicidal activity
  • -anethole
  • estragole
access type Uneingeschränkter Zugang

Effects of the type of biomass and ashing temperature on the properties of solid fuel ashes

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 43 - 51

Zusammenfassung

Abstract

Ashes were prepared by annealing selected types of solid fuels (biomass: corn cobs, sunflower husks, olive pomace, hay pellets and rice husks; coal: lignite and bituminous; and alternative fuel: paper sludge) at different temperatures (550°C, 815°C and 975°C). Based on X-ray fluorescence spectra, the slagging/fouling indexes were used to study the effects of the type of ash and the ashing temperature on the ash fouling and slagging properties. Slagging indexes were compared with the ash fusion temperatures. Ash fusion temperatures were measured by a LECO AF-700. The lowest deformation temperature (below 1000°C) was seen for the ashes prepared from hay pellets and corn cobs. On the other hand, the deformation temperature exceeded 1500°C for ashes prepared from paper sludge, sunflower husks and rice husks. By calculating the different slagging/fouling indexes, all the ashes exhibited slagging/fouling problems of varying degrees.

Schlüsselwörter

  • biomass
  • ashing temperature
  • ash fusion temperature
  • slagging index
  • fouling index
access type Uneingeschränkter Zugang

Strontium-based nanosized phosphates as anticorrosive fillers of epoxy and polyurethane coating compositions

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 52 - 58

Zusammenfassung

Abstract

Anticorrosive epoxy and polyurethane coatings were compounded using zinc-free nanosized phosphates of strontium (SP) or strontium and aluminum (SAP). For comparison, a nanosized calcium aluminum ammonium phosphate (CAP) and a microsized zinc phosphate (ZP) were tested. Results of salts spray and cyclic corrosion tests revealed better anticorrosive properties of the SAP-based coatings in relation to the samples with the other Zn-free fillers or ZP. Electrochemical noise tests of uncoated steel in aqueous suspensions of the phosphates exhibited similar corrosion inhibition efficiency of the Sr-based phosphates and ZP, and worse anticorrosive features of CAP. Electrochemical impedance spectroscopy did not show better protective properties of ZP-based coatings than the samples with the Zn-free fillers.

Schlüsselwörter

  • Strontium phosphate
  • strontium aluminum phosphate
  • calcium aluminum ammonium phosphate
  • zinc phosphate
  • anticorrosive coatings
access type Uneingeschränkter Zugang

Immobilization of permeabilized cells of baker’s yeast for decomposition of H2O2 by catalase

Online veröffentlicht: 28 Jun 2019
Seitenbereich: 59 - 63

Zusammenfassung

Abstract

Permeabilization is one of the effective tools, used to increase the accessibility of intracellular enzymes. Immobilization is one of the best approaches to reuse the enzyme. Present investigation use both techniques to obtain a biocatalyst with high catalase activity. At the beginning the isopropyl alcohol was used to permeabilize cells of baker’s yeast in order to maximize the catalase activity within the treated cells. Afterwards the permeabilized cells were immobilized in calcium alginate beads and this biocatalyst was used for the degradation of hydrogen peroxide to oxygen and water. The optimal sodium alginate concentration and cell mass concentration for immobilization process were determined. The temperature and pH for maximum decomposition of hydrogen peroxide were assigned and are 20°C and 7 respectively. Prepared biocatalyst allowed 3.35-times faster decomposition as compared to alginate beads with non permeabilized cells. The immobilized biocatalyst lost ca. 30% activity after ten cycles of repeated use in batch operations. Each cycles duration was 10 minutes. Permeabilization and subsequent immobilization of the yeast cells allowed them to be transformed into biocatalysts with an enhanced catalase activity, which can be successfully used to decompose hydrogen peroxide.

Schlüsselwörter

  • cell permeabilization
  • baker’s yeast
  • hydrogen peroxide
  • immobilization
  • biocatalyst

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