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od 2020-09-20

Dr hab. Zbigniew Fojud  | 1994-10 - obecnie

Profesor UAM

   WF UAM pokój: 137      +48 61-829-5244       challeng(a)amu.edu.pl

  0000-0003-4810-1858     2774935 / G-2830-2011     6603327507           

Zainteresowania naukowe:
Specjalizuje się w zastosowaniach eksperymentalnych spektroskopii magnetycznego rezonansu jądrowego (ang. – NMR – Nuclear Magnetic Resonance) w badaniach strukturalnych i dynamicznych fazy stałej, w tym również jąder kwadrupolowych (SS-NMR); które uzupełnia wynikami pomiarów technikami DSC, FTIR, BDS. Interesuje się zastosowaniem wysokorozdzielczej spektroskopii HR-NMR do badania strukturalnych aspektów biomolekularnych. Ciekawią go zagadnienia natury technicznej i informatycznej różnych technik obrazowania medycznego lecz głównie techniki MRI (ang. – Magnetic Resonans Imaging), oraz w obrazowaniu multi-modalnym. W wolnych chwilach zajmuje się wytwarzaniem i rozwijaniem oprogramowania na potrzeby eksperymentu fizycznego z użyciem metod inżynierii oprogramowania (ang. – Software Engineering)
Publikacje           Doktorzy      Magistrowie      Licencjusze      Seminaria


50.

Maciejewska B.M., Wychowaniec J.K., Woźniak-Budych M., Popenda Ł., Warowicka A., Golba K., Litowczenko J., Fojud Z., Wereszczyńska B., Jurga S.

UV cross-linked polyvinylpyrrolidone electrospun fibres as antibacterial surfaces Many bacteria become progressively more resistant to antibiotics and it remains a challenging task to control their overall levels. Polymers combined with active biomolecules come to the forefront for the design of antibacterial materials that can address this encounter. In this work, we investigated the photo-crosslinking approach of UV-sensitive benzophenone molecule (BP) with polyvinylpyrrolidone (PVP) polymer within electrospun fibres. The BP and PVP solutions allowed fabricating polymer mats that were subsequently functionalised with antibacterial lysozyme. The physical properties of the crosslinked electrospun fibres were investigated by scanning electron microscopy and atomic force microscopy. The average diameter of the obtained fibres decreased from 290 ± 50 nm to 270 ± 70 nm upon the addition of the crosslinking molecules and then to 240 ± 80 nm and 180 ± 90 nm after subsequent crosslinking reaction at an increasing time: 3 and 5 h, respectively. The peak force quantitative nanomechanical mapping (PF-QNM) indicated the increase of DMT modulus of obtained cross-linked fibres from 4.1 ± 0.8 GPa to 7.2 ± 0.5 GPa. Furthermore, the successful crosslinking reaction of PVP and BP solution into hydrogels was investigated in terms of examining photo-crosslinking mechanism and was confirmed by rheology, Raman, Fourier transform infrared and nuclear magnetic resonance. Finally, lysozyme was successfully encapsulated within cross-linked PVP-BP hydrogels and these were successfully electrospun into mats which were found to be as effective antibacterial agents as pure lysozyme molecules. The dissolution rate of photo cross-linked PVP mats was observed to increase in comparison to pure PVP electrospun mats which opened a potential route for their use as antibacterial, on-demand, dissolvable coatings for various biomedical applications.

Science and Technology of Advanced Materials, 20(1), 979-991 (2019)

DOI: 10.1080/14686996.2019.1667737   (Pobrane:  2020-06-04)

49.

Niziński S., Popenda Ł., Rode M.F., Kumorkiewicz A., Fojud Z., Paluch-Lubawa E., Wybraniec S., Burdziński G.

Structural studies on the stereoisomerism of a natural dye miraxanthin I The chemical structure of a yellow dye present in Mirabilis jalapa L., miraxanthin I, was characterized by NMR spectroscopy. The extract of M. jalapa was analysed by a high-performance liquid chromatographic system (LC-DAD-FL-ESI-MS/MS) and the presence of miraxanthin I among other betaxanthins was confirmed. This dye was synthesized from previously generated methionine-betaxanthin by oxidation with 10% H2O2. The E/Z stereoisomers of miraxanthin I were found by NMR analysis to occur in a 50 : 33 : 10 : 7 ratio in aqueous solution (7E,9E : 7Z,9E : 7E,9Z : 7Z,9Z configurations, respectively). Comparison of NMR data with chemical shifts obtained from quantum chemical calculations strongly suggests the presence of intramolecular hydrogen bonds which may favour a more rigid structure of the dye. This explains the highest fluorescence quantum yield among betaxanthins. The observed changes in the H-1 NMR spectra during the measurements indicate on miraxanthin I hydrolysis for which a mechanism is proposed. The first step during the hydrolysis process is protonation of the nitrogen atom within the central bridge bond system which is observed in the ZE stereoisomer by NMR.

New Journal of Chemistry, 43(46), 18165-18174 (2019)

DOI: 10.1039/c9nj04215f   (Pobrane:  2020-06-04)

48.

Pajzderska A., Fojud Z., Jarek M., Wąsicki J.

NMR relaxometry in the investigation of the kinetics of the recrystallization of felodipine The method of Nuclear Magnetic Resonance (NMR) relaxometry is proposed to be applied to investigate the kinetics of the recrystallization of a substance from the amorphous phase. The method is based on the determination and analysis of nuclear magnetization recovery M-z obtained from spin-lattice T-l relaxation time measurements as a function of time since sample amorphization. The formation of a biphasic (crystalline and amorphous) system in the process of recrystallization implies that the magnetization recovery M-z is biexponential and that the amplitudes of its components are proportional to the number of spins (protons) in the crystalline and amorphous phases, and, thus, also to the volume occupied by the phases. The method was tested for amorphous felodipine samples with grain sizes close to 0.1 or 1 mm, and the recrystallization process was confirmed by using Powder X-ray Diffraction (PXRD) and Fourier-Transform Infrared (FTIR) methods. Qualitative comparison of the results obtained with the data obtained earlier by PXRD and Raman methods for felodipine samples with grain sizes of 0.2 and 0.6 mm [U. S. Kestur, I. Ivanesivic, D. E. Alonzo, L S. Taylor, Influence of particle size on the crystallization kinetics of amorphous felodipine powders, Powder Technology 236 (2013) 197-204] showed reasonable agreement The method is fully extensive and can be applied to amorphous samples prepared in different ways, such as grinding, milling or melting, as well as for co-amorphous or amorphous solid dispersion samples. (C) 2019 Elsevier B.V. All rights reserved.

Powder Technology, 347, 35-41 (2019)

DOI: 10.1016/j.powtec.2019.02.041   (Pobrane:  2020-06-04)

47.

Paczkowska M., Mizera M, Salat K., Furgała A., Popik P., Knapik-Kowalczuk J., Krause A., Szymanowska-Powałowska D., Fojud Z., Kozak M., Paluch M., Cielecka-Piontek J

Enhanced pharmacological efficacy of sumatriptan due to modification of its physicochemical properties by inclusion in selected cyclodextrins The study focused on the pharmacological action of sumatriptan, in particular its antiallodynic and antihyperalgesic properties, as an effect of cyclodextrinic inclusion of sumatriptan, resulting in changes of its physicochemical qualities such as dissolution and permeability through artificial biological membranes, which had previously been examined in vitro in a gastro-intestinal model. The inclusion of sumatriptan into beta-cyclodextrin and 2-hydroxylpropylo-beta-cyclodextrin by kneading was confirmed with the use of spectral (fourier-transform infrared spectroscopy (FT-IR); solid state nuclear magnetic resonance spectroscopy with magic angle spinning condition, H-1 and C-13 MAS NMR) and thermal (differential scanning calorimetry (DSC)) methods. A precise indication of the domains of sumatriptan responsible for its interaction with cyclodextrin cavities was possible due to a theoretical approach to the analysis of experimental spectra. A high-performance liquid chromatography with a diode-array detector method (HPLC-DAD) was employed to determine changes in the concentration of sumatriptan during dissolution and permeability experiments. The inclusion of sumatriptan in complex with cyclodextrins was found to significantly modify its dissolution profiles by increasing the concentration of sumatriptan in complexed form in an acceptor solution compared to in its free form. Following complexation, sumatriptan manifested an enhanced ability to permeate through artificial biological membranes in a gastro-intestinal model for both cyclodextrins at all pH values. As a consequence of the greater permeability of sumatriptan and its increased dissolution from the complexes, an improved pharmacological response was observed when cyclodextrin complexes were applied.

Scientific Reports, 8, 16184 (2018)

DOI: 10.1038/s41598-018-34554-w   (Pobrane:  2019-03-19)

46.

Gołek L., Deja J., Sitarz M., Fojud Z.

The role of aluminium ions during the slag activation process Synthetic glasses with model compositions containing differing amounts of aluminium ions were examined. The model glasses were hydrated under different conditions and with different amounts of NaOH as the activator. X-ray diffraction (XRD), magic angle spinning nuclear magnetic resonance (MAS-NMR), infra-red (IR) spectrometry and strength testing of the hydrated samples was conducted. The heat of hydration was also determined. The composition of glasses is in the gehlenite and anorthite crystal fields. Such glasses are the most popular in industrial slags. Based on the spectroscopic examinations (IR, MAS NMR), it was observed that the aluminium ions are only present in tetrahedral coordination - they are part of the glass network. It was proved that the amount of alumina has significant influence on the hydration process and properties of hardened materials.

Physics and Chemistry of Glasses European Journal of Glass Science and Technology Part B, 55(2), 111-117 (2014)


ISSN: 1753-3562

45.

Hołderna-Natkaniec K., Natkaniec I., Fojud Z., Peplińska B.

An inelastic incoherent neutron scattering study of the internal dynamics of ergocalciferol and cholesterol A model of the methyl group dynamics of two steroid compounds: cholesterol and ergocalciferol was proposed on the grounds of complementary studies performed by inelastic incoherent neutron scattering, nuclear magnetic resonance and quantum chemistry calculation methods.

Journal of Physics: Conference Series, 554(1), 012010 (2014)

DOI: 10.1088/1742-6596/554/1/012010   (Pobrane:  2020-06-25)

44.

Strankowska J., Fojud Z., Jurga S., Strankowski M., White J.L.

Polymer-dependent layer structures in montmorillonite nanocomposites We have studied structural differences among tetrahedral and octahedral sodium Montmorillonite layer arrangements in naturally occurring and synthetic montmorillonite clay minerals, as well as their poly(ethylene oxide) and poly(epsilon-coprolatone) polymer nanocomposites.

Journal of Analytical Science & Technology, 2(A), A22-A30 (2011)

DOI: 10.5355/JAST.2011.A22
WWW: http://www.jastmag.org/journal/view.php?number=52

43.

Jancelewicz M., Fojud Z., Waszkowiak W., Jurga S.

Local mobility in grafted polydimethylsiloxane melts Spin-lattice relaxation time constants T(1) were studied for low-molecular-weight linear and grafted polydimethylsiloxane over a wide temperature and frequency range Quantitative evaluations of proton T(1) measurements indicated two relaxation processes anisotropic rotation of methyl groups around the Si-C bond (low temperature process) and motions of the PDMS side-chains connected with the glass transition (high temperature process) Additional analyses of the T(1) relaxation dispersion profiles revealed specific local segment fluctuation times which are characteristic of the coherent motions in the grafted polymer chains.
(C) 2010 Elsevier Ltd All rights reserved

European Polymer Journal, 47(1), 48-51 (2011)

DOI: 10.1016/j.eurpolymj.2010.10.032

42.

Jancelewicz M., Nowaczyk G., Makrocka-Rydzyk M., Wypych A., Fojud Z., Jurga S., Maciejewski H.

Molecular dynamics in grafted polydimethylsiloxanes Rheological and dielectric behavior of linear PDMS and alkyl-modified PDMS melts has been studied. Molecular dynamics of linear PDMS, being a model of grafted polydimethylsiloxanes studied, has been examined carefully with particular attention paid to its ability to form the semicrystalline phase. Random incorporation of alkyl groups into PDMS chain has been shown to prevent the polymer crystallization. The glass transition temperature of the grafted PDMS changes proportionally to the modifier content. Both techniques allow characterization of the main alpha-relaxation, which is related to the glass transition and exhibits similar behavior in all systems. This relaxation is discussed in terms of the Vogel-Fulcher-Tammann-Hesse (VFTH) approach. The fragility of grafted PDMS materials was found to be higher as compared to the linear polymer. The analysis of the rheological data shows the existence of additional slow relaxation, which has been interpreted as the polymer chain motion.
(C) 2010 Elsevier B.V. All rights reserved.

Journal of Non-Crystalline Solids, 356(11-17), 669-675 (2010)

DOI: 10.1016/j.jnoncrysol.2009.07.036   (Pobrane:  2020-10-21)

41.

Żogał O.J., Fojud Z., Herzig P., Pietraszko A., Lyashchenko A.B., Jurga S., Paderno V.N.

Crystal structure, electric field gradient, and electronic charge densities in ReB2: A single crystal X-ray, 11B nuclear magnetic resonance (NMR) and first-principles study We have grown a single crystal of ReB2 and refined its crystal structure. Our structural studies confirmed the hexagonal structure (space group P6(3)/mmc) with lattice parameters a=2.8982(1) A degrees and c=7.4723(3) A degrees. We also report the observation of first order satellites in the B-11 nuclear magnetic resonance, which indicated the presence of a nonzero quadrupole coupling frequency, nu(Q)=276 ± 3 kHz, and an asymmetry parameter eta=0 at the boron atom sites. These values are in excellent agreement with electric-field-gradient (EFG) tensor calculations based on first principles. These calculations showed that the principal axis of the most negative EFG-tensor component, V-ZZ, is parallel to the c-axis of the crystal. This behavior is in agreement with the observed excess of B p(z) charge (c direction) over the p(x) and p(y) charges and is related to stronger metal-boron bonds compared to previously studied YB12 and LaB6, where the B-B bonds are stronger. Finally, the bonding properties of ReB2 are discussed in terms of densities of states, valence-electron densities, and partial charges.

Journal of Applied Physics, 106(3), 033514-5 (2009)

DOI: 10.1063/1.3190529

40.

Dega-Szafran Z., Fojud Z., Katrusiak A., Szafran M.

Structure of an inclusive compound of bis(piperidinium-4-carboxylate)hydrogen semi-tartrate with water and methanol studied by X-ray diffraction, NMR, FTIR and DFT The complex consisting of two piperidine-4-carboxylic acid, L-tartaric acid, water and methanol molecules has been synthesized and characterized by X-ray diffraction, (1)H, (13)C NMR,(13)C CP MAS NMR, FTIR spectra and DFT calculations. The title complex is composed of the following units: piperidinium-4-carboxylate (P4C), piperidinium-4-carboxylic acid (P4CH), semi-tartrate anion (TA), water and methanol; it crystallizes in orthorhombic space group P2(1)2(1)2(1). TA anions form infinite chains through the COOH center dot center dot center dot OOC hydrogen bond of 2.503(5)angstrom. The zwitterionic P4C molecules are linked by the N(+)H center dot center dot center dot OOC hydrogen bond of 2.780(5) angstrom into chains. The P4CH cation is a bridge between the TA and P4C chains. P4CH and P4C form a homoconjugated cation through the COOH center dot center dot center dot OOC hydrogen bonds of 2.559(5) angstrom. Water interacts with TA and P4CH, while methanol interacts only with water. In the optimized molecule of the (P4C)(2)H center dot TA center dot H(2)O HOCH(3) complex, the components form a cyclic oligomer through four O-H center dot center dot center dot O and four N-H center dot center dot center dot O hydrogen bonds. The (1)H and (13)C NMR spectra elucidate the structure of the title complex in the aqueous solution. The (13)C CP MAS NMR spectrum is consistent with the X-ray results. The FTIR spectrum confirms a very complex structure of the title compound.
(C) 2009 Elsevier B.V. All rights reserved.

Journal of Molecular Structure, 928(1-3), 99-107 (2009)

DOI: 10.1016/j.molstruc.2009.03.021   (Pobrane:  2020-10-23)

39.

Dega-Szafran Z., Fojud Z., Katrusiak A., Szafran M.

CCDC 720706: Experimental crystal structure determination - 4-Carboxypiperidinium 4-piperidiniumcarboxylate hydrogen tartrate methanol solvate monohydrate

Cambridge Structural Database, , (2009)

DOI: 10.5517/ccs5ylg
DBR: http://dx.doi.org/10.5517/ccs5ylg   (Pobrane:  2021-01-07)

38.

Sitarz M., Fojud Z., Olejniczak Z.

The aluminum effect on the structure of silico-phosphate glasses studied by NMR and FTIR Silico-phosphate glasses of NaCaPO(4)-SiO(2) and NaCaPO(4)-AlPO(4)-SiO(2) system have been the subject of the presented investigations. Classes of these systems are the basis for the preparation of glassy-crystalline biomaterials [R.D. Rawlings, Clin. Mater. 14 (1993) 155]. Detailed knowledge of the precursor glass structure is necessary for proper design of the glassy-crystalline biomaterials preparation procedure. Since there is no long-range ordering in glasses, spectroscopic methods which make it possible to study the short range ordering should be applied. MIR studies carried out in the work have allowed to establish that the glasses of the systems studied show domain composition [L.L. Hench, RJ. Splinter, T.K. Greenlee, W.C. Allen, J. Biol. Res. Symp. 2 (1971) 117: L.L. Hench, RJ. Splinter, W.C. Allen, T.K. Greenlee, J. Biol. Res. 5 (1972) 117]. Domain structure is close to that of the corresponding crystalline phases. It has been shown that even small amount of aluminium in the glass (5 mol.% of AlPO(4)) significantly influences both, its texture (microscopic and EDX studies) and its structure (spectroscopic studies). (27)Al NMR investigations have made it possible to establish unequivocally that aluminium occurs exclusively in tetrahedral coordination, i.e. it is involved in the formation of glass framework. Presence of aluminium results in significant changes in the [SiO(4)](4-) and [PO(4)](3-) tetrahedra environment which is reflected in (23)Na, (31)P and (29)Si NMR spectra. Changes in the shapes and positions of the bands in the NMR spectra of glasses belonging to the NaCaPO(4)-AlPO(4)-SiO(2) system confirm great influence of aluminium on silico-phosphate glasses structure.
(C) 2008 Elsevier B.V. All rights reserved.

Journal of Molecular Structure , 924-926, 107-110 (2009)

DOI: 10.1016/j.molstruc.2008.10.043   (Pobrane:  2020-10-23)

37.

Dega-Szafran Z., Dutkiewicz G., Fojud Z., Kosturkiewicz Z., Szafran M.

Ring inversion in 4-hydroxy-1-methylpiperidine betaine studied by X-ray, FTIR, C-13 CP MAS NMR and DFT calculations The structure of the 4-hydroxy-1-methylpiperidine betaine has been determined by X-ray diffraction. The crystals belong to the monoclinic system, space group Pc and unit cell parameters a = 8.972(2), b = 9.747(2), c = 9.562(2) A and beta = 96.10(3)degrees. Two molecules are present in the asymmetric unit. They are in two antipodal chair conformations, in the first (A) with the methyl and hydroxyl groups in the equatorial positions and the CH2COO substituent in the axial one, and in the second (8) with the methyl and hydroxyl groups in the axial positions and the CH2COO substituent in the equatorial One. The molecules A and B form two separated zigzag chains, parallel to the z-axis. In each chain, the molecules are linked by the O-H center dot center dot center dot OOC hydrogen bonds of 2.723(3) and 2.704(3) A, in A and B, respectively. The optimized structure of the A conformer, at the B3LYP/6-31 G(d,p) approach. is by 2.09 kcal/mol more stable than B. Two resonance signals attributed to the CH3 group in C-13 CP MAS NMR spectrum confirm the conformational equilibrium in the solid-state. Two bands at 1631 and 1618 cm(-1) in the solid-state FTIR spectrum suggest the presence of two inequivalent COO groups. The calculated FTIR spectra of conformers A and B differ in the frequencies of the O-H and C-H modes.
(C) 2008 Elsevier B.V. All rights reserved.

Journal of Molecular Structure, 917(2-3), 76-83 (2009)

DOI: 10.1016/j.molstruc.2008.06.032   (Pobrane:  2020-10-25)

36.

Małuszyńska H., Czarnecki P., Fojud Z., Wąsicki J.

Redetermination of the structure and dielectric properties of bis-thiourea pyridinium ioide a new ferroelectric inclusion compounds The crystal structure of bis(thiourea) pyridinium iodide (T(2)PyI) was previously determined at 295 and 110 K [Prout, Heyes, Dobson, McDaid, Maris, Mueller & Seaman (2000). Chem. Mater. 12, 3561-3569] and the two phases were described in the space groups Cmcm and P2(1)cn, respectively. Because differential scanning calorimetry revealed two phase transitions, at 161 and 141 K, a redetermination of the structure of T(2)pyI at 295, 155 and 110 K has been undertaken, and the following sequence of space groups obtained: Cmcm (I) -> C2cm (II) -> P2(1)cn (III). The high- (I) and low- temperature (III) phases confirmed the results reported in the previous study. In the new intermediate phase II, the mirror plane perpendicular to the x axis vanishes and the crystal structure loses the centre of symmetry. In phases I and II the pyridinium cations are strongly dynamically disordered, while in the low-temperature phase III the cations are well ordered. In all three phases the thiourea-iodine hydrogen-bonded sublattice is very well ordered. Dielectric measurements show that the intermediate and low-temperature phases are ferroelectric and that 161 K is the Curie point of a new ferroelectric crystal.

Acta Crystallographica - Section B, Structural Science, B64(5), 567-572 (2008)

DOI: 10.1107/S0108768108018223

35.

Małuszyńska H., Czarnecki P., Fojud Z., Wąsicki J.

COD ID: 2104217, 2104218, 2104219 - bis-thiourea, pyridinium iodide

Crystallography Open Database, , (2008)


DBR: http://www.crystallography.net/information_card.php?cif=2104217   (Pobrane:  2021-01-07)

34.

Nozirov F., Fojud Z., Jancelewicz M., Nazirov A., Jurga S.

Molecular motion in the biocopolymer sequence of glycolide and lactide studied by solid state NMR This paper reports a nuclear magnetic resonance study of the molecular motion in copolymers derived from glycolide and L-lactide in the solid state. Variation of T-1 relaxation times with temperature reflects a local disorder and the fast segment conformational motions which can be quantified in terms of correlation times predicted by the Bloembergen-Purcell-Pound and Davidson-Cole models. At low temperatures, spin relaxation is dominated by the axial methyl rotation in lactide units described by an asymmetry parameter of the correlation time delta which takes a value of about 0.45 for all systems. Above the devitrification points the trans and gauche isomerization in glycolide segments occurs. In addition to the chemical structure characterization, solid-state magic-angle spinning spectroscopy gives an insight into the role of glycol segments in the chain mobility.

Applied Magnetic Resonance, 34(1-2), 193-203 (2008)

DOI: 10.1007/s00723-008-0102-z   (Pobrane:  2020-10-23)

33.

Wąsicki J., Pajzderska J., Fojud Z.

Temperature dependence of spontaneous polarization in order-disorder pyridinium periodate extracted from 2H NMR data On the basis of occupancy factor data for nitrogen atoms in the pyridinium cation obtained from the structural study of PyHIO4 by neutron diffraction,(4) the shape of the potential for cation reorientation about the axis perpendicular to its plane was found. The H-2 NMR spectra of d(5)PyHIO(4) taken over a wide range of temperatures have allowed the determination of potential minima populations. These data were used to obtain the temperature dependence of spontaneous polarization. The agreement between the spontaneous polarization calculated in this way and the measured values is very good and indicates that the ferroelectric crystal is of the order-disorder type.

Journal of Physical Chemistry C, 112(19), 7503-7508 (2008)

DOI: 10.1021/jp711762n

32.

Herzig P., Fojud Z., Żogał O. J., Pietraszko A., Dukhnenko A., Jurga S., Shitsevalova N.

Electric-field gradient tensor and charge densities in LaB6: 11B NMR single-crystal investigations and first-principles calculations B-11 nuclear-magnetic-resonance measurements on a B-11 enriched single crystal of LaB6 have been performed at room temperature at a frequency of 128.4 MHz. The electric-field-gradient (EFG) tensor components have been determined from the angle dependence of the quadrupole splittings associated with (-3/2 <->-1/2) and (3/2 <-> 1/2) satellite transitions. These EFG components have been calculated using first-principles methods. Very satisfactory agreement with the experimental values has been obtained. The calculations show that the largest component of the EFG tensor mainly comes from the pp part of the so-called sphere component. The principal axis for the most negative EFG component is oriented in direction of the shortest and strongest bond between neighboring B atoms, which belong to two different B-6 units (interoctahedral B-B bonds). The fact that these interoctahedral B-B bonds are aligned in three different directions is responsible for the observation of up to three satellite pairs, although all boron atoms are crystallographically equivalent and there exists only one EFG tensor. Apart from the EFG investigations, chemical bonding in LaB6 is analyzed from densities of states and electron-density plots.
(C) 2008 American Institute of Physics.

Journal of Applied Physics, 103(8), 083534-7 (2008)

DOI: 10.1063/1.2903150   (Pobrane:  2020-10-21)

31.

Wąsicki J., Fojud Z., Czarnecki P., Jurga S.

Polarisation and energy barriers in ferroelectric pyridinium perchlorate Polycrystalline sample of pyridinium perchlorate was studied by NMR method in the temperature range from 133 to 313 K. Assuming a reorientation of pyridinium cations over inequivalent potential energy barriers in the low-temperature and intermediate phases a temperature dependence of an asymmetry parameter was determined from analysis of 2H line shape. By using the known potential shape and population of its minima, a temperature dependence of the spontaneous polarisation was calculated. The polarisation determined in this way compared with that measured by the pyroelectric effect revealed the mixed type of ferroelectricity in the crystal studied: the order-disorder and displacive one.

Ferroelectrics, 368(1p2), 63-71 (2008)

DOI: 10.1080/00150190802367927   (Pobrane:  2020-07-25)

30.

Orozbaev B., Fojud Z., Makrocka-Rydzyk M., Schroeder G., Jurga S.

Molecular dynamics of podand studied by broadband dielectric and nuclear magnetic resonance spectroscopies Nuclear magnetic resonance (NMR) and broadband dielectric spectroscopies (BDS) were used toanalyze the molecular dynamics in P10.3H Podand. The temperature studies of NMR line and magnetic spin-lattice relaxation times accompanied by DS investigation enabled us to distinguish three main dynamical processes connected with the motions of the P10.3H Podand chains. In the low-temperature region the magnetic relaxation was associated with fast axial C-3 rotation of methyl groups. Moreover, two other independent processes were observed and interpreted as (i) segmental motion of both oxyethylene and ethylene units, and (ii) the overall motion involved in the melting process.

Macromolecular Chemistry and Physics, 208(19-20), 2121-2127 (2007)

DOI: 10.1002/macp.200700197   (Pobrane:  2008-01-09)

29.

Fojud Z., Herzig P., Żogał O. J., Pietraszko A., Dukhnenko A., Jurga S., Shitsevalova N.

Electric-field-gradient tensor and boron site resolved 11B NMR in single-crystalline YB12 B11 NMR measurements on a single crystal of YB12 have been performed at room temperature at a frequency of 128.4 MHz. The electric-field-gradient (EFG) tensor components and the principal axes calculated previously by first-principles methods have been verified experimentally. Three magnetically different boron-atom groups in the B12 cluster were clearly observed for the crystal orientation used in this work. This distinction results from different EFG-tensor orientations with respect to magnetic field and not from different quadrupolar splittings (νQ) or asymmetry-parameter values (η). The magnetically different boron atoms have been identified through the calculated angle dependence of the satellite transitions (0°–360°). Very satisfactory agreement between the calculated and experimental angular dependencies of the EFG tensor has been obtained. Similarly, the quadrupolar splittings and asymmetry parameters agree very well with those previously determined from NMR measurements on a powder sample of YB12.
(C)2007 American Physical Society

Physical Review B - Condensed Matter and Materials Physics, 75(18), 184102 (2007)

DOI: 10.1103/PhysRevB.75.184102   (Pobrane:  2020-10-21)

28.

Pajzderska A., Fojud Z., Goc R., Wąsicki J.

Cation dynamics in pyridinium nitrate and bis-thiourea pyridinium nitrate inclusion compound studied by 2H NMR spectroscopy H-2 NMR ( nuclear magnetic resonance) line-shape measurements were performed over a wide temperature range for pyridinium nitrate (d(5)PyH) NO3 and bis-thiourea pyridinium nitrate inclusion complex T-2(d(5)PyH) NO3 in order to compare the dynamics of d(5)-pyridinium cation in both compounds. It was revealed that in both systems the pyridinium cation undergoes reorientations about the axis perpendicular to its plane, among inequivalent potential energy barriers. However, in (d(5)PyH) NO3 (no phase transition) the population of the deepest minima decreases monotonically up to the melting point, whereas in T-2(d(5)PyH) NO3 (two phase transitions) this population decreases rapidly in a transition to the high-temperature phase and its value does not depend on temperature. In bis-thiourea pyridinium nitrate inclusion compound the out-of-plane motion of the cation is also found in the intermediate- and high-temperature phases, and the amplitudes of the motion are equal to 20 degrees and 35 degrees, respectively. On the basis of the assumptions of these models, it is possible to reproduce the experimental H-2 NMR line shapes in an excellent way.

Journal of Physics: Condensed Matter, 19(15), 156220 (2007)

DOI: 10.1088/0953-8984/19/15/156220

27.

Brycki B., Zieliński A., Konieczna M., Fojud Z., Nowicki M., Jurga J.

Struktura modułów alkiloamino-fulerenowych z polimerami Zastosowanie pochodnych fulerenowych do modyfikacji struktury molekularnej i powierzchniowej polimerów ma istotne znaczenie przy wytwarzaniu nanokompozytów do zastosowań w elektronice, przemyśle elektrooptycznym, tekstylnym i opakowaniowym. Pochodne te charakteryzują się znaczną reaktywnością elektrofilową w stosunku do nieorganicznych i organicznych cząstek paramagnetycznych. W szczególności mogą stanowić układy molekularne rekombinujące wolne rodniki w materiałach polimerowych. Celem niniejszej pracy było otrzymanie adduktów fulerenu C60 z tlenkiem tetracyjanoetenu (TCNEO) oraz z n-decyloaminą (NH2C10H21), które jako makroinicjatory, wprowadzone w różnych proporcjach do polimerów alkilo-fenylenowych stanowią nanokompozyty o potencjalnym znaczeniu praktycznym.

Mat. VIII Środowiskowa Konf. Nauk. Chemików "Chemia w zrównoważonym rozwoju", , 165-168 (2006)


ISBN: 83-89723-X    (Pobrane:  2020-06-04)

26.

Pająk Z., Czarnecki P., Szafrańska B., Małuszyńska H., Fojud Z.

Ferroelectric ordering in imidazolium perchlorate Imidazolium perchlorate has been synthesized and studied over a wide range of temperatures by differential scanning calorimetry, x-ray diffraction, proton magnetic resonance, optical observation, and dielectric spectroscopy. Polymorphic solid-solid phase transitions have been disclosed at 487, 373, and 247 K. The crystal structure at 298 K has been determined as trigonal, space group R (3) over barm, Z=1 with alpha=5.484(1) angstrom and alpha=95.18(2)degrees. The imidazolium cations are strongly disordered, while the perchlorate ions are well ordered. At 385 K the crystal structure remains trigonal, space group R (3) over barm, alpha=5.554(1) angstrom and alpha=95.30(2)degrees. Both ionic sublattices are orientationally disordered. Temperature evolution of the molecular dynamics of the imidazolium cation has been characterized. In spite of a high cationic disorder, dielectric measurements have revealed the polar properties of the crystal. It appears to be a new ferroelectric compound with the Curie point at 373 K. The spontaneous polarization originates predominantly from the behavior of slightly distorted perchlorate anion.
(C) 2006 American Institute of Physics.

Journal of Chemical Physics, 124(14), 144502 (2006)

DOI: 10.1063/1.2185098   (Pobrane:  2020-10-21)

25.

Krzaczkowska J., Fojud Z., Kozak M., Jurga S.

Spectroscopic studies of poly(epsilon-caprolactone)/sodium montmorillonite nanocomposites Polymer-layered silicate nanocomposites belong to a new class of hybrid materials consisting of organic-synthetic polymer matrix and inorganic filler-layered structure clay minerals. The paper presents the results of FTIR, NMR, and SAXS studies of poly( epsilon -caprolactone)/sodium montmorillonite nanocomposites. We observed a correlation between the concentration of poly( epsilon -caprolactone) in nanocomposite samples and structural changes both of the clay mineral and the intercalated polymer. Stiffening of the clay structure appears as a result of poly(epsilon -caprolactone) intercalation into a clay structure. 27Al NMR studies indicated in nanocomposites two non-equivalent sites of aluminium ions, i.e. in octahedral and tetrahedral coordination, whereas in the montmorillonite clay structure the aluminium ions are located in the interlayer space too. We found also that the temperatures of structural changes and softening process of poly( epsilon-caprolactone) chains in the nanocomposites depend on the concentration of poly( epsilon -caprolactone).

Acta Physica Polonica A, 108(1), 187-196 (2005)

DOI: 10.12693/APhysPolA.108.187
WWW: http://przyrbwn.icm.edu.pl/APP/PDF/108/a108z124.pdf   (Pobrane:  2021-01-10)

24.

Lubas M., Sitarz M., Fojud Z., Jurga S.

Structure of multicomponent SiO2-Al2O3-Fe2O3-CaO-MgO glasses for the preparation of fibrous insulating materials Glasses used for the fabrication of fibrous insulating materials are made from natural raw materials, mainly basalts. Basalt alloys, however, show relatively high crystallization capability, which is disadvantageous for throwing and durability of the fibres prepared. In the work new raw materials, such as melaphyres and diabase from the Silesia region of Poland were applied for the preparation of aluminosilicate alloys. In order to study their crystallization ability the glasses were heated in an electric furnace at various temperatures for various time periods. Depending on the raw material used as well as the temperature of heat-treatment amorphous or crystalline materials were obtained. Crystalline phases were identified based on X-ray diffraction studies. It was found that magnetite/titanomagnetite crystallized in the first step. Then pyroxenes phases of diopsides or augite type appeared in the systems. Spectroscopic investigations in the mid IR region were carried out for all the glasses. This made it possible to determine the influence of thermal treatment on the structural changes of glasses (changes in the spectra shapes). Locations of the bands due to Al-O-Si and Si-O-Si bridges vibrations suggested that in most cases the augite-type phases were present in the systems (aluminium coordination number equal to 4 and 6). Appearance of aluminium in coordination 4 and 6 was confirmed by NMR investigations (two clear bands in the spectra).
(C) 2004 Elsevier B.V. All rights reserved.

Journal of Molecular Structure, 744-747, 615-619 (2005)

DOI: 10.1016/j.molstruc.2004.12.011   (Pobrane:  2020-10-21)

23.

Sitarz M., Handke M., Fojud Z., Jurga S.

Spectroscopic studies of glassy phospho-silicate materials The aim of the work is to determine the internal structure of bioactive glasses based on structural studies. Due to the absence of the long-range order, the X-ray methods usually applied in the studies of crystalline materials are of low applicability in the investigations of glasses. Therefore, spectroscopic methods, such as IR and NMR, which make it possible to 'see' the short- and the middle-range order are extremely suitable in their studies. IR investigations have shown that the glasses studied exhibit non-uniform domain composition, which should facilitate their transformation into glass-crystalline state. Additionally, detailed NMR measurements have been carried out in order to determine the influence of glass structure on the course of its crystallization. These studies make it possible to verify the common opinions on the middle-range order (domains) in the glasses studied. The results obtained for Al-27 and P-31 are particularly promising. Changes in the environment Of [SiO4](4-) tetrahedra, which can be spatially connected with various numbers Of [PO4](3-) and [AlO4](5-) tetrahedra cause the presence of various types of bridging bonds, such as Si-O-Si, Si-O-Al and Si-O-P. This in turn has significant impact on the number and the shape of the bands occurring in the spectra.
(C) 2005 Elsevier B.V. All rights reserved.

Journal of Molecular Structure, 744-747, 621-626 (2005)

DOI: 10.1016/j.molstruc.2004.12.050   (Pobrane:  2020-10-23)

22.

Łodziński M., Sitarz M., Stec K., Kozanecki M., Fojud Z., Jurga S.

ICP, IR, Raman, NMR investigations of beryls from pegmatites of the Sudety Mts Detailed ICP, IR, Raman and NMR investigation were performed for more than 50 samples of beryls from pegmatites in the Sudety Mts. MIR spectra were measured at room (293 K), low up to 22 K and high up to 1273 K temperatures. The absorption bands for studied samples of beryl are correlated with chemical composition and structural parameters. The samples represent both alkali-poor (potassium-bearing, sodium-potassium-bearing) and alkali-rich (sodic and sodic-lithian) members of the beryl group. Two types of H2O molecules are discerned in all studied beryls. The I-type is not connected with alkali with bands at 3697/3690 cm(-1), 3647/3630/3610 cm(-1) (3606 cm(-1) in Raman spectra) and 1602/1550 cm(-1) dominates over the II-type (hydrated anions of alkali) with bands at 3660 cm(-1), 3592/3590 cm(-1) (3597 cm(-1) in Raman spectra) and 1637/1630cm(-1). CO2 molecules (2360 cm(-1) in MIR spectra, 1386 cm(-1), 1240 cm(-1) in Raman spectra) and hydroxyl groups in subordinate quantities occur in structural channels of beryls, except for mentioned above. Main bands in the range of 1200-400 cm(-1) are diagnostic in discerning of the three types of beryls according to lattice parameter classification. Studied beryls, in the most cases, belong to normal-type. Some samples are octahedral-type, and do not occur tetrahedral beryls in the Sudety Mts.
(C) 2005 Elsevier B.V. All rights reserved.

Journal of Molecular Structure, 744-747, 1005-1015 (2005)

DOI: 10.1016/j.molstruc.2004.12.042   (Pobrane:  2020-10-21)

21.

Trejda M., Lazar K., Decyk P., Fojud Z., Jurga S., Ziółek M.

Generation of iron active species in MCM-41 materials A new method, the immobilisation or ferroceneacetic acid (FAA) on various MCM-41 mesoporous molecular sieves (containing Si or Si+Al) followed by calcination at 773 K has been applied for the formation of iron active species. The structural, surface and catalytic properties of these materials, characterised by N-2 adsorption/desorption, XRD, Al-27 NMR, ESR, and Mossbauer spectroscopy as well as test reactions, were compared with those of materials prepared via commonly used impregnation methods. Contrary to Fe-impregnated samples, Fe oxides species were only slightly detected in the solids modified by FAA followed by calcination. It is evidenced that the new technique applied for Fe-modification gives rise to the significantly higher activity (in isopropanol decomposition and acetonylacetone cyclization) reached thanks to a better isolation and/or dispersion of Fe3+ species. The presence of Al in the sample influences the Fe3+ reduction under vacuum.

Studies in Surface Science and Catalysis A, 158 A, 829-836 (2005)

DOI: 10.1016/s0167-2991(05)80419-7   (Pobrane:  2021-01-02)

20.

Kozak M., Foltynowicz Z., Jakubiak P., Fojud Z., Domka L., Jurga S.

Preparation and structural study of the composites of polyethylene with modified bentonite The paper reports a study on obtaining and characterisation of organophilised bentonite. Modification of the bentonite studied has been confirmed by SEM, XRD and NMR results. The organoplilised filler has been used for preparation on nanocomposites based on polyethylene or polyethylene modified with vinyltriethoxysilane and lactic acid. The best mechanical parameters have been obtained for the composites on the basis of the modified polyethylene containing 4% of organophilised bentonite and 50% of lactic acid.

Mat. VI Konferencji Naukowo-Technicznej "Polimery i Kompozyty Konstrukcyjne", , 69-74 (2004)

   (Pobrane:  2021-01-08)

19.

Pająk Z., Czarnecki P., Szafrańska B., Małuszyńska B., Fojud Z.

Ferroelectric order in highly disordered molecular-ionic crystals The ordering of the anionic sublattice at the coexisting high orientational disorder of the cationic sublattice produces spontaneous polarization in imidazolium tetrafluoroborate [C3N2H5]+ [BF4]-. This ferroelectric crystal exhibits the Curie point at 297.0 K and undergoes two other polymorphic phase transitions at 213.6 and 187.8 K. In spite of its pentagonal ring the dynamically disordered polar cation is localized at a special position on the threefold axis of the highly symmetrical rhombohedral unit cell. Thus it does not contribute immediately to the spontaneous polarization which originates predominantly from the behavior of the distorted tetrahedral fluoroborate anion.

Physical Review B - Condensed Matter and Materials Physics, 69(13), 132102 (2004)

DOI: 10.1103/PhysRevB.69.132102   (Pobrane:  2020-10-23)

18.

Jurga J., Woźniak-Braszak A., Fojud Z., Jurga K.

Proton longitudinal NMR relaxation of poly(p-phenylene sulphide) in the laboratory and the rotating frames reference Spin-lattice NMR relaxation times T-1 in the laboratory frame and T1 as well as Toff in the rotating frame off-resonance were employed to the study of molecular dynamics of both pristine PPS and thermally treated poly(p-phenylene sulfide) (PPS). The temperature dependence of T-1 was exponential in the whole temperature range studied, whereas T1ρ only in low temperatures. In the high temperature range the distribution of relaxation times T1ρ and correlation times tau(c) as well as activation energy E. was observed. The distribution of activation energy determined from T-1 minima at 15 and 30 MHz and from low temperature slopes of T1ρ dependence as well as from spectral density functions (estimated from proton off-resonance technique) was attributed to the reorientation of phenylene groups around the sulfur-phenyl-sulfur axis in amorphous and crystalline phases of PPS. Furthermore, it is suggested that an additional relaxation mechanism related to interactions of protons with paramagnetic centers is operative in a low temperature range. After thermal treatment of PPS the low temperature minima disappeared and the relaxation times shortened in the low temperature regime. Both these facts were attributed to an increased contribution of spin diffusion in the relaxation process.
(C) 2003 Elsevier Inc. All rights reserved.

Solid State Nuclear Magnetic Resonance, 25(1-3), 47-52 (2004)

DOI: 10.1016/j.ssnmr.2003.03.014   (Pobrane:  2020-10-23)

17.

Jurga K., Fojud Z., Woźniak-Braszak A.

NMR strong off-resonance irradiation without sample overheating A prototype NMR probe for long RF pulse has been constructed. Its main elements are two coils mounted in the concentric position. The first bigger coil is wound around a glass dewar tube and the second smaller coil is placed inside the dewar. These two coils are thermally isolated by the dewar. A long and strong RF pulse is applied to the bigger coil. The smaller detection coil inside the dewar contains a sample and to this coil a short RF pulse is applied. The two coils are independently tuned and electrically isolated. During the operation of the strong RF pulse the smaller coil has a high resistance to ground (very low Q factor) and does not absorb energy from the bigger coil. During the operation of the short on-resonance RF pulse the bigger coil is detuned to a higher frequency, but the resonance circuit with the small coil is in the electrical resonance. The NMR probe may be used in off-resonance experiments in which long and strong RF pulses are applied to the bigger coil and thereby the problem of the sample overheating is avoided.
(C) 2003 Elsevier Inc. All rights reserved.

Solid State Nuclear Magnetic Resonance, 25(1-3), 119-124 (2004)

DOI: 10.1016/j.ssnmr.2003.05.001   (Pobrane:  2020-10-21)

16.

Fojud Z., Szcześniak E., Jurga S., Stapf S., Kimmich R.

Molecular dynamics of n-dodecylammonium chloride in aqueous solutions investigated by 2H NMR and 1H NMR relaxometry Molecular dynamics in n-dodecylammonium chloride/water solutions for concentrations of 34 and 45wt% was studied by 2H NMR and by H-1 NMR dispersion of spin-lattice relaxation in the 2 kHz-90 MHz frequency range. The system exhibits a number of lyotropic liquid crystalline phases, which differ in symmetry and involve motions characterized by a wide frequency scale. The analysis of H-2 NMR lineshapes of selectively deuterated DDACl molecules gave us an evidence for local trans-gauche conformational changes in the chains, whereas the dispersion of spin-lattice relaxation times T, explored by fast field cycling method revealed fast local motions, translational diffusion and collective molecular dynamics of the chains. In particular, we have found that the order director fluctuation mechanism in smectic and nematic phases dominates spin-lattice relaxation below I MHz and that local motions and translational diffusion are responsible for the spin-lattice relaxation in the higher Larmor frequency range.
(C) 2003 Elsevier Inc. All rights reserved.

Solid State Nuclear Magnetic Resonance, 25(1-3), 200-206 (2004)

DOI: 10.1016/j.ssnmr.2003.07.002   (Pobrane:  2020-10-21)

15.

Czarnecka D., Ciesielska D., Jurga J., Fojud Z.

Brittle-ductile transition (BDT) recycled poly(ethylene-terethalate) - PET The paper is concerned with the influence of reprocessing on molecular, rheological and mechanical properties of recycled polymers. The injection moulded specimens made of virgin and recycled material after 4-cycles and 6-cycles of processing poly(ethylene terephthalate) - PET EASTAPAK 9921 were investigated. The deformation and character of cracking (brittle-ductile) were determined from the analyse of stress-strain curves as a function of temperature. The brittle-ductile transition was characterised by the Ludwig- Davidenkov-Orowan (LDO) criterion. The mechanical behaviour was assessed in tensile testing at 250 mm/min and at various temperature. The results showed that the point of brittle-ductile transition (BDT) shifts to higher temperature and to lower stress. The character of fracture was taken using a TESCAN scanning electron microscope (SEM). The thermal properties of a virgin and recycled PET (glass transition, melting point and crystallinity) were characterized by differential scannning calorimetry (DSC). Solution viscosity measurements were carried out in an viscosimeter equipped with Ubbelhode capillaries. The investigation showed that the recycling polymers cause the degradation of polymer what is evidenced in intrinsic viscosity, average molecular weight and the degree of crystallinity recycled poly(terephthalate ethylene). This effect caused the increase of brittleness and reduced the load-carrying of products made from recycled polymers.

Polymer Processing Society PPS-20, , 204 (2003)

   (Pobrane:  2020-10-23)

14.

Fojud Z., Goc R., Kozak A., Jurga S., Wąsicki J.

Polarisation and energy barriers in ferroelectric pyridinium tetrafluoroborate The measurements of 1H and 19F NMR second moment were performed for a polycrystalline sample of (PyH)BF4, whereas the shape of 2H NMR line was analysed for a polycrystalline sample of (d5PyH)BF4. Asymmetry parameter D has been calculated for four models of pyridinium cation reorientation among inequivalent potential energy minima, using experimental value of 1H NMR second moment as well as the 2H NMR line width. Knowing the potential shape and the population of its minima the temperature dependence of polarisation for all the models has been found. From the comparison of the experimentally determined polarisation with the calculated one the most appropriate model of the pyridinium cation reorientation has been chosen.

Molecular Physics, 101(10), 1469-1476 (2003)

DOI: 10.1080/0026897031000082167

13.

Jurga J., Jurga K., Woźniak-Braszak A. and Fojud Z.

Molecular dynamics of modified poly(p-phenylene sulfide) Solid state proton NMR dynamics of poly(p-phenylene sulfide) (PPS) is studied by using off-resonance technique. It is shown that this method is able to provide indirect information about the correlation times of the internal motions. The obtained results are in a good agreement with those reported in the literature for the same system but using other NMR methods.

Polymer Processing Society PPS-18, , 219-223 (2002)

12.

Mozgawa W., Fojud Z., Handke A., Jurga S.

MAS NMR and FTIR spectra of framework aluminosilicates In the work, the results of Al-27 MAS NMR studies carried out for structures of different framework aluminosilicates are presented. The spectra of natural clinoptilolite and its sodium and hydrogen forms were measured. The zeolite spectra were obtained before and after incorporation of heavy metal cations (Pb2+, Cd2+, Ni2+ and Cr3+) into the zeolite structure. After decomposition of the spectra into component peaks differences caused by ion exchange were observed. Additionally, NMR spectra of kalsilite (framework aluminosilicate, not belonging to zeolite group) and other zeolites (chabazite, heulandite and analcime) were measured. Al-27 MAS NMR spectra of all the samples studied were compared with the FTIR spectra measured in the middle infrared region. Based on the results obtained it has been proved that the interpretation of spectra obtained using these two different techniques can give some information concerning changes occurring in various framework aluminosilicate structures.
(C) 2002 Elsevier Science B.V. All rights reserved.

Journal of Molecular Structure, 614(1-3), 281-287 (2002)

DOI: 10.1016/S0022-2860(02)00262-4   (Pobrane:  2020-10-21)

11.

Nozirov F., Szcześniak E., Fojud Z., Dobrzyński P., Klinowski J., Jurga S.

1H and 13C NMR studies of molecular dynamics in the biocopolymer of glycolide and epsilon-caprolactone Copolymers of glycolide and F-caprolactone were studied using differential scanning calorimetry and solid-state NMR. The variation of the T-1 relaxation time with temperature reflects local disorder and can be quantified in terms of the distribution of correlation times predicted by the Davidson-Cole model. T-1 relaxation is dominated by trans gauche lisomerisation, with an activation energy of 34-35 kJ mol(-1).
(C) 2002 Elsevier Science (USA).

Solid State Nuclear Magnetic Resonance, 22(1), 19-28 (2002)

DOI: 10.1006/snmr.2002.0056   (Pobrane:  2020-10-21)

10.

Nozirov F., Fojud Z., Klinowski J., Jurga S.

High-resolution solid-state 13C NMR studies of poly[(R)-3-hydroxybutyric] acid Solid poly[(R)-3-hydroxybutyric] acid was examined by high-resolution C-13 MAS NMR, differential scanning calorimetry and infrared spectroscopy. The C-13 methyl group resonance consists of three components: the rigid amorphous phase, the crystalline phase and the mobile amorphous phase. Spectral deconvolution, using the Lorentz function, reveals the relative amounts as 62% crystalline and 38% amorphous at 333 K, and 42% crystalline, 40% pure amorphous and 18% beta-orthorhombic at 413 K. NMR indicates a large difference in molecular mobility between the crystalline and amorphous regions of the sample. Infrared spectroscopy shows that the stretching at 1725 cm(-1) (characteristic of the a-form) comes from the crystalline region, and the bands at 1744 cm(-1) (characteristic of the beta-form) and 1800 cm(-1) come from the amorphous region.
(C) 2002 Elsevier Science (USA).

Solid State Nuclear Magnetic Resonance, 21(3-4), 197-203 (2002)

DOI: 10.1006/snmr.2002.0060   (Pobrane:  2020-10-23)

9.

Foltynowicz Z., Jakubiak P., Judek Ł., Kozak M., Kuśmia S., Fojud Z., Domka L., Jurga S.

Polietylen modyfikowany mleczanem wapnia W pracy przedstawiono metodę otrzymywania polietylenu modyfikowanego mleczanem wapnia oraz pochodną krzemoorganiczną mleczanu wapnia. Stosowano różne ilości napełniacza. Uzyskane tworzywa biorozpraszalne poddano badaniom mechanicznym.

Mat. V Konferencji Naukowo-Technicznej "Polimery i Kompozyty Konstrukcyjne", , 61-65 (2002)

8.

Fojud Z., Jurga S.

High resolution 13C NMR and DSC studies of interdigitated- noninterdygitated phase transition in a series of alkylammonium chloridies Relation between length of the n-alkylammonium chains and phase transitions in series of alkylammonium chlorides is studied by DSC and 13C CPMAS NMR experiment. The results show that the phase transitions revealed by DSC and NMR are related with a motional freedom of CH2 and CH3 in the chains.

Molecular Physics Reports, 33, 172-174 (2001)

WWW: http://www.ifmpan.poznan.pl/mol/
ISSN: 1505-1250   (Pobrane:  2021-01-07)

7.

Wachowicz M., Fojud Z., Jurga S.

Fast field cycling proton NMR relaxation in decylammonium chloride/water system We have investigated the dispersion of the proton spin-lattice relaxation times in decylammonium chloride/water systems, which exhibit different liquid crystalline phases of isotropic (micelles), lamellar (layers), hexagonal (layers rolled up into cylinders), and of nematic structures. The measurements were performed in the frequency range from 3·10^3 to 1.6·10^7 Hz and in the temperature range from 10°C to 85°C. The analysis of relaxation dispersion curves gave us information on local collective molecular dynamics of the alkylammonium chains.

Molecular Physics Reports, 33, 176-178 (2001)

WWW: http://www.ifmpan.poznan.pl/mol/
ISSN: 1505-1250   (Pobrane:  2021-01-07)

6.

Czapla Z., Fojud Z., Cieślik J., Jurga S.

New aproach to assessment of aging processes at the cellular level by NMR spectroscopy The paper presents results of the proton relaxation time T1 measurements by 1H NMR for oral epithelium samples taken from 320 subjects, men and women, in different age, from 19 to 95 year old. The times of nuclear magnetic relaxation T1 were found to be correlated with the age of the subjects.

Molecular Physics Reports, 29, 228-231 (2000)

WWW: http://www.ifmpan.poznan.pl/mol/
ISSN: 1505-1250   (Pobrane:  2021-01-07)

5.

Fojud Z., Jurga S.

A study of interdygitated-noninterdygitated phase transition on n-octadecylammonium chloride C18H37NH3Cl by 13C CPMAS NMR An interrelation between the interdigitated-noniterdigitated phase transition and molecular dynamics of the alkylammonium chains in C18H37NH3Cl is studied by means of 13C CPMAS experiment . The results of the measurements of 13C spectra as a function of temperature show that the observed phase transition is related with a motional freedom of the methylene groups.

Molecular Physics Reports, 29, 47-50 (2000)

WWW: http://www.ifmpan.poznan.pl/mol/
ISSN: 1505-1250   (Pobrane:  2021-01-07)

4.

Nozirov F., Fojud Z., Szcześniak E., Jurga S.

Molecular dynamics in poly[(R)-3-hydroxybutyric acid] biopolymer as studied by NMR Nuclear magnetic resonance line shapes and spin-lattice relaxation rimes T-1 of H-1 and H-2 nuclei of poly[(R)-3-hydroxybutyric acid] have been measured in the temperature range 100-413 K. The results provide information on the local dynamics of the compound. Activation parameters of the revealed motion are determined.

Applied Magnetic Resonance, 18(1), 37-45 (2000)

DOI: 10.1007/BF03162097

3.

Fojud Z., Szcześniak E., Jurga K., Jurga S.

Molecular dynamics of n-dodecylammonium chloride studied by nuclear magnetic resonance The relation between molecular dynamics and phase properties of the bilayered compound C12H25NH3Cl is studied by differential scanning calorimetry, proton second moment, and spin-lattice relaxation Limes. In the low-temperature Phase I of the compound methyl and ammonium groups execute a classical threefold reorientation, while the alkylammonium chains are rigid on the nuclear magnetic resonance time scale. In the intermediate-temperature phase delta a trans-gauche isomerization of the alkyl chains is observed. In the high-temperature phase alpha the reorientation of the whole chains about their long axes, which are parallel to the normal to the ionic layer is evidenced. In the meta-stable epsilon phase the dynamics involves classical rotation of methyl and ammonium groups and CH2 groups motion of the trans-gauche isomerization type.

Applied Magnetic Resonance, 19(3-4), 413-420 (2000)

DOI: 10.1007/BF03162384

2.

Fojud Z., Boeffel C., Szcześniak E., Jurga S.

2H and 13C CPMAS NMR study of chain dynamics in n-dodecylammonium chloride The H-2 NMR spectra of the selectively deuterated polycrystalline n-dodecylammonium chloride as well as C-13 CPMAS spectra of this compound are studied over a wide range of temperature. The results reveal a variety of phase transitions occurring in this model bilayer system and make it possible to relate them to the local molecular dynamics of the alkyl chains.
(C) 2000 Elsevier Science B.V. All rights reserved.

Journal of Molecular Structure, 555, 107-117 (2000)

DOI: 10.1016/S0022-2860(00)00592-5   (Pobrane:  2020-10-21)

1.

Czapla Z., Fojud Z.

The appraisal of the scope for the application of nuclear magnetic resonance (NMR) measurement methods for the estimation of the biological age in various stages of human ontogeny The main objective of the study is to find a new physical parameter meeting the criterion of the biological age estimation in various stages of human ontogeny, and thus to find a new research methodology for this fields of research. For this purpose an NMR Bruker 200 MHz spectrometer was used. Two physical parameters: relaxation time (T1) and spectrum shape were determined. The research material was oral mucosa epithelium sampled in a group of young people of both sexes (31 subjects) and in a group of men (18 subjects). Relaxation time (T1) and spectrum shape were recorded for hydrogen nuclei (1H). The physical phenomena were analyzed statistically (regression analysis) and their biological interpretation was attempted.

Variability and Evolution, 7, 87-98 (1999)

WWW: http://www.staff.amu.edu.pl/~anthro/html/varevol.html   (Pobrane:  2020-06-04)

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