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AKTUALNOŚCI / NEWS

2013

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M. Bazarnik, J. Brede, R. Decker, R. Wiesedanger"Tailoring Molecular Self-Assembly of Magnetic Phthalocyanine Molecules on Fe- and Co-Intercalated Graphene"ACS Nan...

2014

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R. Decker, M. Bazarnik, N. Atodiresei, V. Caciuc, S. Blügel, R. Wiesendanger"Local tunnel magnetoresistance of an iron intercalated graphene-based heterostructure...

2015

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A. Racis, L. Jurczyszyn, M. Bazarnik, W. Koczorowski, A. Wykrota, R. Czajka, M.W. Radny"Self-organisation of inorganic elements on Si(001) mediated by pre-adsorbed...
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2015

  1. A. Racis, L. Jurczyszyn, M. Bazarnik, W. Koczorowski, A. Wykrota, R. Czajka, M.W. Radny
    "Self-organisation of inorganic elements on Si(001) mediated by pre-adsorbed organic molecules"
    Physical Chemistry Chemical Physics, 17 (2015) 23783-23794

    Abstract

     A combined theoretical and experimental study on the adsorption of an isolated benzonitrile molecule on the Si(001) surface, followed by the adsorption of Al (group III), Pb (carbon group) and Ag (transition metal) is presented. It is shown that two new adsorption sites with enhanced reactivity are formed on the surface in the vicinity of the pre-adsorbed molecule. This is evidenced by the increase of the calculated binding energy of the metallic ad-atoms adsorbed at these sites. Experimentally, this enhanced local reactivity of the modified surface is only partially retained when more metallic atoms are adsorbed on the modified surface at room temperature. This is evidenced by the formation of 1-dimensional atomic chains (Pb, Al) attached to one side of the pre-adsorbed molecule.
  2. M. Bazarnik, L. Jurczyszyn, R. Czajka, K. Morgenstern
    "Mechanism of a molecular photo-switch adsorbed on Si(100)"
    Physical Chemistry Chemical Physics, 17 (2015) 5366-5371

    Abstract

     We present a very compact molecular photoswitch on the technologically important Si(100) surface. Its adsorption configuration is determined by a combined scanning tunneling microscopy (STM) and density functional theory (DFT) study. The mechanisms of the isomerization reactions are discussed in view of DFT calculations and proven by in situ light irradiation.
  3. M. Bazarnik, R. Decker, J. Brede, R. Wiesendanger
    "Multi-layer and multi-component intercalation at the graphene/Ir(111) interface"
    Surface Science, 639 (2015) 70-74

    Abstract

     We present a scanning tunneling microscopy study of Fe and Co intercalated at the graphene–Ir(111) interface. In the case of Fe, we investigate the morphology of the surface with respect to the annealing temperature, which activates the intercalation, and as a function of coverage. By increasing the coverage we show that it is possible to intercalate multilayers at the interface. Finally, we demonstrate that the successive intercalation of Co and Fe for the same sample leads to distinct adjacent intercalation areas.
  4. S. El-Ahmar, A. A. Poźniak
    "Modeling the planar configuration of extraordinary magnetoresistance"
    Journal of Physics D: Applied Physics, 48 (2015) 205101

    Abstract

     Recently the planar version of the extraordinary magnetoresistance (EMR) magnetic field sensor has been constructed and verified in practice. Planar configuration of the EMR device gives many technological advantages, it is simpler than the classic and allows one to build the sensor using electric materials of the new type (such as graphene or topological insulators) much easier. In this work the planar configuration of the EMR sensor is investigated by performing computational simulations using the finite element method (FEM). The computational comparison of the planar and classic configurations of EMR is presented using three-dimensional models. Various variants of the geometry of EMR sensor components are pondered and compared in the planar and classic version. Size of the metal overlap is considered for sensor optimization as well as various semiconductor-metal contact resistance dependences of the EMR signal. Based on computational simulations, a method for optimal placement of electric terminals in a planar EMR device is proposed.
  5. Z. Pietralik, Ż. Kołodziejska, M. Weiss, M. Kozak
    "Gemini Surfactants Based on Bis-Imidazolium Alkoxy Derivatives as Effective Agents for Delivery of Nucleic Acids: A Structural and Spectroscopic Study"
    PLoS ONE, 10(12) (2015) e0144373

    Abstract

     The success rate of gene therapy depends on the efficient transfection of genetic material into cells. The golden mean between harmlessness and high effectiveness can be provided by synthetic lipid-like molecules that are similar to the components of biological membranes. Cationic gemini surfactants are one such moiety and because of their favourable physicochemical properties (double positive electric charge, reduced toxicity, low values of critical micelle concentration), they show great potential as delivery system components for genetic material in gene therapy. The aim of this study was to investigate the process of the complexation of cationic gemini surfactants with nucleic acids: double-stranded DNA of different sizes (21 bp, ~185 bp, ~20 kbp) and siRNA (21 bp). The tested series of dicationic surfactants consists of bis-imidazolium quaternary salts with varying lengths of hydrophobic side chains (m = 5, 6, 7, 8, 9, 11, 12, 14, 16). On the basis of the data obtained by circular dichroism spectroscopy and electrophoresis, we concluded that the studied gemini surfactants with long side chains effectively bind nucleic acids at low concentrations, which leads to the formation of stable lipoplexes. Images obtained by atomic force microscopy also confirmed the formation of vesicular structures, i.e., complexes between DNA and surfactants. The cytotoxicity of selected surfactants was also tested on HeLa cells. The surfactant toxicity significantly depends on surfactant geometry (the length of hydrophobic chain).
  6. A. Wykrota, M. Bazarnik, R. Czajka, K. Morgenstern
    "A molecular switch based on the manipulation of 1,3-dichlorobenzene on Ge(001) between two adsorption sites by inelastic tunneling electrons"
    Phys. Chem. Chem. Phys. 17 (2015) 28830-28836

     Abstract

     Meta-dichlorobenzene is adsorbed on Ge(001) and investigated by low temperature scanning tunneling microscopy. The molecule is altered between two adsorption sites by inelastic electron tunneling manipulation. These adsorption sites differ largely in conductivity. The necessary energy for switching the molecule between the sites and its polarity dependence indicate that the manipulation is initiated by the electronic excitation of the molecule.
  7. M. Baczyńska, M. Regel-Rosocka, M. Nowicki, M. Wiśniewski
    "Effect of the structure of polymer inclusion membranes on Zn(II) transport from chloride aqueous solutions"
    Journal of Applied Polymer Science, 132(30) (2015) 42319

    Abstract

    This article presents application of polymer inclusion membranes (PIM) containing polymer matrices: cellulose triacetate (CTA) or poly(vinyl) chloride (PVC), o-nitrophenyloctyl ether (NPOE) as a plasticizer and phosphonium ionic liquids, i.e., trihexyltetradecylphosphonium chloride (Cyphos IL 101), bis(2,4,4-trimethylpentyl)phosphinate (Cyphos IL 104) and tributyltetradecylphosphonium chloride (Cyphos IL 167), as carriers for Zn(II) transport from chloride medium. Cyphos IL167 application as an ion carrier in PIMs is reported for the first time. The membrane composition is found to affect Zn(II) transport significantly. SEM and AFM images show the differences in the surface morphology of PVC and CTA based membranes. Better transport abilities of CTA membranes (Zn(II) recovery factors exceed 80%) compared with those of PVC, indicate that the structural differences between the two polymers play a crucial role for the membrane permeability. The best initial flux and permeability coefficient are obtained for the membranes with Cyphos IL 101 and Cyphos IL 104 as carriers.
  8. P. Jezowski, M. Nowicki, M. Grzeszkowiak, R. Czajka, F. Béguin
    "Chemical etching of stainless steel 301 for improving performance of electrochemical capacitors in aqueous electrolyte"
    Journal of Power Sources, 279 (2015) 555-562

    Abstract

    The main purpose of the study was to increase the surface roughness of stainless steel 301 current collectors by etching, in order to improve the electrochemical performance of electrical double-layer capacitors (EDLC) in 1 mol L-1 lithium sulphate electrolyte. Etching was realized in 1:3:30 (HNO3:HCl:H2O) solution with times varying up to 10 min. For the considered 15 mu m thick foil and a mass loss around 0.4 wt.%, pitting was uniform, with diameter of pits ranging from 100 to 300 nm. Atomic force microscopy (AFM) showed an increase of average surface roughness (Ra) from 5 nm for the as-received stainless steel foil to 24 nm for the pitted material. Electrochemical impedance spectroscopy realized on EDLCs with coated electrodes either on as-received or pitted foil in 1 mol L-1 Li2SO4 gave equivalent distributed resistance (EDR) of 8 Omega and 2 Omega, respectively, demonstrating a substantial improvement of collector/electrode interface after pitting. Correlatively, the EDLCs with pitted collector displayed a better charge propagation and low ohmic losses even at relatively high current of 20 A g(-1). Hence, chemical pitting of stainless steel current collectors is an appropriate method for optimising the performance of EDLCs in neutral aqueous electrolyte.
  9. M. Wladyka-Przybylak, D. Wesołek, S. Rojewski, R. Gąsiorowski, W. Gieparda, K. Bujnowicz, H. Maciejewski, R. Wójcik, M. Nowicki
    "Synergistic Effect of Modified Natural Fibres with Halogen-Free Fire Retardants in Reducing Flammability of Composites"
    J. Biobased Mater. Bioenergy, 9 (2015) 115-127

    Abstract

    Silanization process was used to improve adhesion of hydrophilic hemp fibers with a hydrophobic polypropylene matrix. The modification of fibers was carried out using 3-(diethylenetriamine)propyltrimetoxysilane. Natural fibres reinforced composites (NFRC) were obtained by mixing the polypropylene (PP) with untreated and silane modified hemp fibres using co-rotating twin screw Leistritz extruder. The flame retardants such as multiwalled carbon nanotubes (CNT), ammonium polyphosphate (APP), guanidinium carbonate (GC), pentaerythritol (PEr) and melamine polyphosphate (MPP) were introduced into the NFRC by a Dynisco laboratory extruder. The influence of silanization process on the chemical structure of fibers was studied by Fourier transform infrared spectroscopy (FTIR). The surface morphology of the untreated and silane treated fibres and their impact on the polymer matrix were characterized by scanning electron microscopy (SEM). Interactions between the additives and their impact on the thermal stability of the fibres, polymers and composites was investigated using thermogravimetric analysis (TGA). Combustibility measurements were carried out by pyrolysis combustion flow calorimeter (PCFC). The improvement in the thermal stability of hemp fibres as a result of silanization process and higher efficiency of modified fibers in reducing the flammability of polypropylene were found as compared with the unmodified fibers. The results showed synergistic effect between silanized hemp fibres and carbon nanotubes in reducing flammability and increasing thermal stability of the composites. All of the used compounds in combination with silanized natural fibres decrease flammability of polypropylene with the best results observed for ammonium polyphosphate and melamine polyphosphate.
  10. L. Słomińska, R. Zielonka, L. Jarosławski, A. Krupska, A. Szlaferek, W. Kowalski, J. Tomaszewska-Gras, M. Nowicki
    "High pressure impact on changes in potato starch granules"
    Polish Journal of Chemical Technology, 17(4) (2015) 65-73

    Abstract

    Air dry potato starch (84.9% d.s.) was subjected to pressurizing under the pressure of 50, 100, 250, 500, 750, 1000 and 2000 MPa for 1 h. The physical properties of pressurized starch, such as morphology, surface and crystalline structure, gelatinization parameters, were studied by means of scanning and atomic force microscopy (SEM/AFM), X-ray diffraction (X-ray), differential scanning calorimetry (DSC). The susceptibility to the amylolytic enzyme (α-amylase) was also measured. Application of pressure in the range of 50–2000 MPa results in an increase in the compressed potato starch bulk density, change in the contours of the granules from oval to polyhedral, increase in the roughness of the granule surface, vanishing of the X-ray reflexes generated by the orthogonal structure and weakening of the reflexes generated by the hexagonal structure, lowering of the enthalpy of starch gelatinization, and the enhancement of hydrolytic susceptibility of starch granules to the amylolytic enzyme.
  11. P. Żak, B. Dudziec, M. Dutkiewicz, M. Ludwiczak, B. Marciniec, M. Nowicki
    "A new class of stereoregular vinylene-arylene copolymers with double-decker silsesquioxane in the main chain."
    J. Polym. Sci. Part A: Polym. Chem., 54(8) (2015) 1044-1055

    Abstract

    A synthesis of a new macromolecular class of vinylene-arylene copolymers with double-decker silsesquioxane in the main chain is presented. Two transition-metal-catalyzed processes, which is silylative-coupling copolycondensation (SCC) and ADMET copolymerization of divinyl-substituted double-decker silsesquioxanes (DDSQ-2SiVi) with selected diolefins, are reported to be highly efficient tools for the formation of stereoregular copolymers containing DDSQ-silylene-vinylene-arylene units. The copolymeric products are studied in terms of their structural, thermal, and mechanical properties.