Up

Volume 3, Year 2012, Issue 4, October-December

Volume 3, Year 2012, Issue 4, October-December

New microfluidic device for lactate dehydrogenase (LDH) activity analysis
Author:
Elżbieta Jędrych, Małgorzata Mazur, Ilona Grabowska-Jadach, Zbigniew Brzózka
Downloads:
3272 x
 

 

Abstract: In this paper, we present cytotoxicity analysis (determination of lactate dehydrogenase — LDH activity performed in a designed and fabricated microfl uidic system. Th is method allowed for analysis of a supernatant collected from A549 (human lung cancer) and HT-29 (human colon cancer epithelial) cells, which were incubated for 24 h with selected compounds. LDH is an intracellular enzyme present in tissues, which is released into the supernatant caused by membrane damage or cell lyses. In our tests, LDH-Cytotoxicity Assay Kit (BioVision) was used. Th e toxic eff ect of drugs was measured in the developed microsystem made of PDMS (poly(dimethylsiloxane)). Analytical reaction took place in the special designed microchannel geometry. Th en, the LDH activity was measured at 490 nm using spectrophotometer. In subsequent experiments, appropriate conditions for measurements using a microfl uidic system were chosen. It was found that the selected reagent is sensitive to temperature changes and light exposure. Reaction time in the microsystem was determined by changes of fl ow rates of reagents. Afterwards, for the various reaction time, the toxic eff ect of 5-fl uorouracil, celecoxib and 1,4-dioxane was performed. Th e obtained results were compared with the results carried out in 96-well plates. Based on these results, it was noted that the enzymatic reaction time in the microsystem is shorter than in 96-well plate. Moreover, the advantage of using microsystem is also the small amount of reagents.

Keywords: lactate dehydrogenase (LDH) activity, microfl uidic system, PDMS, adherent cell culture, cytotoxicity analysis

Area: Biomedical Engineering

BibTeX:

@article{Jedrych2012a,
  author = {Elżbieta Jędrych and Małgorzata Mazur and Ilona Grabowska-Jadach and Zbigniew Brzózka},
  title = {New microfluidic device for lactate dehydrogenase (LDH) activity analysis},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {3--8},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/107-new-microfluidic-device-for-lactate-dehydrogenase-ldh-activity-analysis}
}
Functionalization of polyurethane surfaces for further attachment of bioactive molecules
Author:
Barbara Marczak, Beata Butruk, Tomasz Ciach
Downloads:
5 x
 

 

Abstract: The challenge for cardiovascular tissue engineers is to design hemocompatible biomaterials that promote neo-tissue formation. Cardiovascular implants are prone to occlusion caused by surface thrombogenicity. In native tissue non-thrombogenic surface is provided by the endothelium. Endothelialization of implantable cardiovascular devices is thereby among the techniques of functionalizing biomaterials. Surfaces covered with peptides have been shown to enhance endothelial cells adhesion and proliferation. For the purpose of further cell-specifi c peptides immobilization, a three-step method for incorporating carboxyl groups onto a polyurethane surface was developed. In the fi rst step silanol groups were incorporated into the polyurethane surface. Successful reaction was proven by FTIR analysis. Subsequently, incorporation of surface amine groups was proceeded. In the last step amine groups were acylated using glutaric anhydride to create carboxylates. To determine the presence of surface functional groups, colorimetric method was applied. Measurement of water contact angle revealed signifi cant increase in surface hydrophilicity.

Keywords: material engineering, surface modifi cation, polyurethane modifi cation, polyurethane activation, silanization

Area: Biomedical Engineering

BibTeX:

@article{Marczak2012,
  author = {Barbara Marczak and Beata Butruk and Tomasz Ciach},
  title = {Functionalization of polyurethane surfaces for further attachment of bioactive molecules},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {9--13},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/108-functionalization-of-polyurethane-surfaces-for-further-attachment-of-bioactive-molecules}
}
Screen printed resistive pressure sensors fabricated from polymer composites with carbon nanotubes
Author:
Daniel Janczak, Grzegorz Wróblewski, Małgorzata Jakubowska,Marcin Słoma, Anna Młoźniak
Downloads:
6 x
 

 

Abstract: The paper presents the results of the investigation into fl exible layers based on carbon nanotubes used as measuring layer in force sensor. Results of mechanical fatigue tests show that carbon nanotubes layers are good for reinforcing or as a conductive additive in composite materials. Composition of carbon nanotubes in PMMA polymer resin was prepared by modifi ed mixing process used in thick film material preparation. Sensor structure was fabricated by printing polymer-nanotube areas with polymer-silver paths as connection electrodes on polyester substrate foil. Second type of sensors was prepared with two comb electrodes and single carbon measuring layer. Composite materials were fabricated with diff erent amount of nanotube content: 0,25 wt%, 0,5 wt%, 1 wt% and 2 wt% multiwall carbon naotubes (MWCNT). Diff erent types of carbon-composites measuring layers were compared in the  experiment. Results of mechanical fatigue tests conducted on carbon nanotubes layers showed that composition with polymer resin have good adhesion to polymer surface. Experiment shows CNT are good for reinforcing or as a conductive additive in diff erent composite materials. Results of the observations show that dependence between sensor resistance and force tension is linear in logarithmic scale and similar for diff erent samples. Resistance between sensor electrodes was measured for force tension changes in range 10N to 20kN. Better results were observed for sensors with comb electrodes and low content of carbon nanotubes.

Keywords: resistive polymer nanocomposite, pressure sensors, carbon nanotubes, thick film technology, contact resistance

Area: Nanotechnologies and Materials

BibTeX:

@article{Janczak2012,
  author = {Daniel Janczak and Grzegorz Wróblewski and Małgorzata Jakubowska and Marcin Słoma and Anna Młoźniak},
  title = {Screen printed resistive pressure sensors fabricated from polymer composites with carbon nanotubes},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {14--19},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/109-screen-printed-resistive-pressure-sensors-fabricated-from-polymer-composites-with-carbon-nanotubes}
}
Influence of supercritical carbon dioxide on structure and mechanical properties of porous polypropylene membranes
Author:
Jan Krzysztoforski, Andrzej Krasiński, Marek Henczka, Wojciech Piętkiewicz, Maciej Szwast
Downloads:
12 x
 

 

Abstract: The influence of supercritical carbon dioxide (scCO2) on structure and mechanical properties of porous polypropylene tubular membranes subjected to diff erent process conditions was investigated. Th e membranes were treated with scCO2 at pressure of 18 MPa and at three diff erent temperatures (40°C, 70°C, and 100°C) for 2 h in a batch reactor. Th e obtained samples were analyzed using a scanning electron microscope (SEM) to determine the impact on the membrane structure, tensile testing for ultimate strength assessment, and bubble point test for determination of the pore size distribution and the fi ltration coeffi cient (UFC). A membrane not treated with scCO2 was used as reference sample for comparison. SEM pictures of side surfaces and cross-sections of treated tubular membranes did not reveal any changes in membrane structure. Tensile testing of treated and non-treated samples showed that after scCO2 treatment the ultimate strength slightly decreased (less than 10%), while the Young’s modulus was reduced by almost 50%. Th e bubble point test showed that scCO2 causes an increase in the number of pores and an increase in the UFC value. In the range 40–100°C no signifi cant temperature dependence was observed. Th e results confi rm that supercritical carbon dioxide can be used as a medium in porous polypropylene membrane production, maintenance and modifi cation.

Keywords: supercritical fl uid, membrane, TIPS, supercritical carbon dioxide

Area: Nanotechnologies and Materials

BibTeX:

@article{Krzysztoforski2012,
  author = {Jan Krzysztoforski and Andrzej Krasiński and Marek Henczka and Wojciech Piętkiewicz and Maciej Szwast},
  title = {Influence of supercritical carbon dioxide on structure and mechanical properties of porous polypropylene membranes},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {20--25},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/110-influence-of-supercritical-carbon-dioxide-on-structure-and-mechanical-properties-of-porous-polypropylene-membranes}
}
Activity of perovskite catalysts contain Pt or Pd in toluene oxidation
Author:
Agnieszka Borzęcka
Downloads:
9 x
 

 

Abstract: Perovskite catalysts with active phase composed of LaMnO3 or La0.75Ag0.25MnO3 doped with noble metals — platinum or palladium — were tested for activity in oxidation of toluene. Th eir impregnation with solution of Pt or Pd compounds increased the catalytic activity. LaMnO3 with Pt content displayed the highest activity. LaMnO3 perovskite doped with both noble metals show higher activity than when noble metals were added to La0.75Ag0.25MnO3 perovskite

Keywords: catalytic VOCs oxidation, perovskite, platinum, palladium

Area: Natural Sciences

BibTeX:

@article{Borzeck2012,
  author = {Agnieszka Borzęcka},
  title = {Activity of perovskite catalysts contain Pt or Pd in toluene oxidation},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {26--28},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/111-activity-of-perovskite-catalysts-contain-pt-or-pd-in-toluene-oxidation}
}
Influence of EDTA on stabilization of decarboxylated betalains
Author:
Anna Skopin´ska, Karolina Starzak, Sławomir Wybraniec
Downloads:
5 x
 

 

Abstract: Betalains are known to be very sensitive to several factors, including higher temperature, therefore, the studies on their stability are essential for the food industry. In order to determine the stability of betanin derivatives during thermal treatment, a set of degradation experiments was performed, including the protective infl uence of EDTA as a chelating agent. The pigments were dissolved in aqueous solutions of acetonitrile, methanol and ethanol. The studies on thermal degradation of the pigments confi rmed their high lability in all investigated solvents. Under the infl uence of protective activity of EDTA, the rate of the degradation of the decarboxylated betalains was substantially decreased. The analysis of obtained absorption spectra of the degradation products indicated that under the infl uence of EDTA, the products retained the basic chromophoric skeleton.

Keywords: betacyanins, decarboxylation, Beta vulgaris L., EDTA

Area: Natural Sciences

BibTeX:

@article{Skopinska2012,
  author = {Anna Skopińska and Karolina Starzak and Sławomir Wybraniec},
  title = {Influence of EDTA on stabilization of decarboxylated betalains},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {29--33},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/112-influence-of-edta-on-stabilization-of-decarboxylated-betalains}
}
Spectrophotometric study on betanin photodegradation
Author:
Anna Skopińska, Dorota Tuwalska, Sławomir Wybraniec, Karolina Starzak, Katarzyna Mitka, Piotr Kowalski, Maciej Szaleniec
Downloads:
7 x
 

 

Abstract: Redbeet root (Beta vulgaris L.), used for production of food colorants on a commercial scale [1]. Due to photo-lability of betacyanins, an eff ect of UV-irradiation on betanin degradation in various solutions containing organic solvents was investigated. Organic solvents are used frequently in many stages of pigment preparation or isolation, therefore, knowledge of betalain stability and degradation characteristics in these solutions is essential. Pigment solutions at a concentration of 1 mg/ml were prepared in diff erent solvents: water as well as aqueous solutions of 50% (v/v) acetonitrile, 50% (v/v) methanol or 50% (v/v) ethanol, at the pH range 3–8. Acetate, phosphate and citrate buffers were used for the experiments. As a result of the pigment photo-decomposition, numerous decarboxylated and dehydrogenated derivatives were formed. Spectrophotometric studies enabled determination of the pigment retention (percentage of the pigment residue relative to its initial concentration after decomposition time). The studies demonstrated betanin high lability in all solvents, not only at extreme pH values, but also in the middle pH range which, in general, provides higher stability of betalains.

Keywords: betanin, betacyanins, photodegradation, Beta vulgaris L

Area: Natural Sciences

BibTeX:

@article{Skopinska2012a,
  author = {Anna Skopińska and Dorota Tuwalska and Sławomir Wybraniec and Karolina Starzak and Katarzyna Mitka and Piotr Kowalski and Maciej Szaleniec},
  title = {Spectrophotometric study on betanin photodegradation},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {34--38},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/113-spectrophotometric-study-on-betanin-photodegradation}
}
Research on betanidin oxidation by ABTS radicals
Author:
Karolina Starzak, Anna Skopińska, Sławomir Wybraniec
Downloads:
5 x
 

 

Abstract: Betanidin is a basic betacyanin with 5,6-dihydroxyl moiety which causes its high antioxidant activity. It belongs to betalains, a group of natural, water-soluble plant pigments, which elicit a red-violet coloration of fruits and fl owers. One of the most popular sources of betanidin is red beet root (Beta vulgaris L.). Recent studies have shown importance of betalains oxidation, because of their high natural, antiradical and antioxidant activity and potential benefi ts for human health [1]. An eff ect of oxidation of betanidin using ABTS radicals was investigated in aqueous solutions at pH 3–8 and compared to activity of horseradish peroxidase. Products of the biomimetic betanidin oxidation were monitored by high performance liquid chromatography (HPLC) coupled to optical detection and mass spectrometry (LC-DAD-ESI-MS/MS). Th e presence of two main oxidation products: 2-decarboxy-2,3-dehydro-betanidin and 2,17-didecarboxy-2,3-dehydro-betanidin at pH 3 indicates their generation through two possible reaction ways with two diff erent quinonoid intermediates: dopachrome derivative and quinone methide. Both reaction paths lead to the decarboxylative dehydrogenation of betanidin.

Keywords: betanidin, betalains, antioxidation activity, ABTS, radicals

Area: Natural Sciences

BibTeX:

@article{Starzak2012a,
  author = {Karolina Starzak and Anna Skopińska and Sławomir Wybraniec},
  title = {Research on betanidin oxidation by ABTS radicals},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {39--43},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/114-research-on-betanidin-oxidation-by-abts-radicals}
}
Spectrophotometric investigation on betanin degradation induced by copper cations
Author:
Karolina Starzak, Anna Skopińska, Sławomir Wybraniec
Downloads:
15 x
 

 

Abstract: Betanin pigment structurally belong to red-violet betacyanins which represent a class of N-heterocyclic water soluble plant pigments providing the colours in a wide variety of fl owers and fruits [1, 2]. Most of betacyanins, such as betanin, are 5-O-glucosides of betanidin (the basic chromophoric aglycone unit). Betanin colorant (E-162) is produced from red beet roots
(Beta vulgaris L.) and is available in concentrates produced by evaporating beet juice under vacuum or as powders made by spray-drying the concentrate. In this study, an eff ect of copper cations on betanin stability was investigated in aqueous and organic-aqueous solutions. Th e presence of organic solvents (methanol, ethanol and acetonitrile) increased substantially the ecomposition of the pigment induced by metal cations in acidic media, for which generally much lower degradation in aqueous solutions was observed. A possibility of a complex formation between betanin and Cu2+ was also stated at pH 7–8 and its relatively high stability in aqueous samples was observed. A presence of numerous products of betanin decomposition was noticed at the wavelength range of 380–500 nm in spectra obtained for the investigated metal cations, especially in the organic-aqueous solutions.

Keywords: betanin, betalains, heavy metals, copper, degradation, UV-Vis spectra, spectrophotometry

Area: Natural Sciences

BibTeX:

@article{Starzak2012,
  author = {Karolina Starzak and Anna Skopińska and Sławomir Wybraniec},
  title = {Spectrophotometric investigation on betanin degradation induced by copper cations},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {44--48},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/115-spectrophotometric-investigation-on-betanin-degradation-induced-by-copper-cations}
}
Peptone as a nitrogen source for erythritol production from glycerol by Yarrowia lipolytica yeast
Author:
Ludwika Tomaszewska
Downloads:
1 x
 

 

Abstract: Erythritol is a compound widely distributed in nature. It found application in medicine, cosmetics, chemical and food industry. It has 60–80% sweetness in comparison to sucrose, very low energy value (~0.2 kcal/g), is non-cariogenic and free of gastric side-eff ects. Th is sugar alcohol is commercially produced in microbiological processes using glucose and sucrose. Glycerol, which is produced in large amounts by biodiesel industry, can be used as alternative substrate for the production of erythritol by Yarrowia lipolytica yeast. Th e aim of the study was to examine the impact of peptone on erythritol production from glycerol by Wratislavia K1 strain of Y. lipolytica. In the 10-days shake-fl asks experiment the peptone concentration of 1–12 g/L were examined. Pure glycerol (98% wt/wt) was used as carbon and energy source. Th e media were supplemented with 2.5% and 5% of NaCl. Th e results showed that peptone could be used as nitrogen source in erythritol biosynthesis from glycerol by Y. lipolytica yeast. Th e best results were achieved with 2 g/L of peptone and 5% of NaCl, where yeast produced 18.2 g/L of erythritol, corresponding to 0.23 g/g yield, 0.11 g/(Lh) volumetric productivity and specifi c production rate of 0.010 g/(gh). In this conditions minimal level of of by-products was formed — arabitol production was not observed while mannitol, citric acids and -ketoglutaric acid did not exceed 0.4, 4.4 and 2.0 g/L, respectively.

Keywords: erythritol, glycerol, Yarrowia lipolytica, peptone

Area: Natural Sciences

BibTeX:

@article{Tomaszewsk2012,
  author = {Ludwika Tomaszewska},
  title = {Peptone as a nitrogen source for erythritol production from glycerol by Yarrowia lipolytica yeast},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {49--52},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/116-peptone-as-a-nitrogen-source-for-erythritol-production-from-glycerol-by-yarrowia-lipolytica-yeast}
}
Reduction of railway bridge vibration with groundhook mass damper
Author:
Michał Wcisło
Downloads:
7 x
 

 

Abstract: The aim of this research is to compare eff ectiveness of an ordinary mass damper with a more complex one equipped with an extra spring element connecting the damper mass with the ground. For both simple- and nonlinear- primary structure models and for stable load state, theoretically effi ciency of both types of dampers is just the same therefore their effi ciencies  in bridge structures subjected to non-stationary load are investigated.

Keywords: mass damper, bridge dynamics, non-stationary load

Area: Town and Urban Planning, Architecture and Building Engineering

BibTeX:

@article{Wcislo2012,
  author = {Michał Wcisło},
  title = {Reduction of railway bridge vibration with groundhook mass damper},
  journal = {Challenges of Modern Technology},
  year = {2012},
  volume = {3},
  number = {4},
  pages = {53--57},
  url = {http://www.journal.young-scientists.eu/index.php/isuues/file/117-reduction-of-railway-bridge-vibration-with-groundhook-mass-damper}
}
 
 
Powered by Phoca Download