Zakład Fizyki Biomedycznej
Strona główna
Zespół
Badania
Aparatura
Seminaria
Publikacje
Nasze
konferencje
Aktywność
konferencyjna
Projekty
Programy
Najbliższe
wydarzenia
Linki
Kontakt

wizyta

od 2020-09-20

Dr Marek Kempka  | 1994-10 - obecnie

Starszy specjalista

   WF UAM pokój: 150      +48 61-829-5245       markem@amu.edu.pl

  0000-0002-2012-599X     6603064690     

Zainteresowania naukowe:
Dynamika molekularna fazy skondensowanej. Spektroskopia Laplace'a w dyfuzometrii magnetycznego rezonansu jądrowego.
Metodyka i aparatura badawcza.
Publikacje           Doktorzy      Magistrowie           Seminaria


35.

Kristinaityte K., Zalewski T., Kempka M., Sakirzanovas S., Baziulyte-Paulaviciene D., Jurga S., Rotomskis R., Valeviciene N.R.

Spin-lattice relaxation and diffusion processes in aqueous solutions of gadolinium-based upconverting nanoparticles at different magnetic fields We investigated the influence of gadolinium (Gd)-based upconverting nanoparticles (UCNPs) on water spin-lattice relaxation (T-1) and diffusion at different magnetic field strengths (0.4T and 9.4T). Our findings show that smaller NPs (12nm compared to 19nm) were more favourable for proton relaxivity. We also demonstrate that using simplified Solomon-Bloembergen-Morgan (SBM) model we can associate two measured diffusion coefficients with processes occurring near the surface of UCNPs and in bulk water. Using the relationship between relaxation and diffusion, we can estimate not only the total impact of NPs on relaxation of water molecules, but also the impact on relaxation of local water molecules, directly connected to paramagnetic Gd3+ ions in NPs. Different magnetic field strengths did not alter the spin-lattice relaxivity of NPs. This suggests that Gd-based UCNPs could be developed into high-performance multimodal magnetic resonance imaging contrast agents working over a broad range of imaging field strengths used in clinical routine.

Applied Magnetic Resonance, 50(4) SI, 553-561 (2019)

DOI: 10.1007/s00723-018-1105-z   (Pobrane:  2020-12-28)

34.

Skupin-Mrugalska P., Sobotta Ł., Warowicka A., Wereszczyńska B., Zalewski T., Gierlich P., Jarek M., Nowaczyk G., Kempka M., Gapiński J., Jurga S., Mielcarek J.

Theranostic liposomes as a bimodal carrier for magnetic resonance imaging contrast agent and photosensitizer The present study is focused on the development of liposomes bearing gadolinium chelate (GdLip) providing two functionalities for magnetic resonance imaging (MRI) and photodynamic therapy of cancer. A lipid derivative of gadolinium(III) diethylenetriamine pentaacetic acid salt (GdDTPA1) was inserted in the liposomal membrane and served as MRI contrast agent whereas a zinc phthalocyanine (ZnPc) was used as a model photosensitizer. In addition to conventional liposomes, pegylated lipids were used for the preparation of "stealth" liposomes. The characterization of different GdLip formulations involved evaluation of the liposomes size by nanoparticle tracking analysis, thermal phase behavior by differential scanning calorimetry and ZnPc-mediated singlet oxygen production. Furthermore, relaxivity measurements were performed as well as cytotoxicity and photodynamic activity against cancerous and normal cell lines was studied. Size and thermal behavior were only slightly influenced by GdLip composition, however it distinctly affected singlet oxygen production of ZnPc-loaded GdLip. The quantum yields of singlet oxygen generation by zinc phthalocyanine incorporated in GdLip containing cationic or/and pegylated lipids were smaller than those obtained for non-pegylated carriers with l-alpha-phosphatidylglycerol. In general, all formulations of GdLip, irrespectively of composition, were characterized by relaxivities higher than those of commercially used contrast agents (e.g. Magnevist). NMR study has shown that the incorporation of ZnPc into the formulations of GdLip increases the relaxation parameters r1 and r2, compared to the values for the non-loaded vesicles. GdDTPA1 did not influence the photodynamic activity of ZnPc against HeLa cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Journal of Inorganic Biochemistry, 180, 1-14 (2018)

DOI: 10.1016/j.jinorgbio.2017.11.025   (Pobrane:  2018-03-20)

33.

Masewicz Ł., Lewandowicz J., Le Thanh-Blicharz J., Kempka M., Baranowska H.M.

Diffusion of water in potato starch pastes The aim of the work was to describe water transport in two-component biopolymer-water systems on the basis of water activity measurements. Research material consisted oi physically (drum dried) and differently chemically modified starches (E1404, E1412, E1414, E1422). A phenomenological model was proposed which takes into consideration water transport in the gel and surface effects associated with evaporation. It was found, that water molecules in such systems undergo diffusion in two phases. Moreover, utilization of comprehensive results of water activity measurements as well as the model proposed in this study provide detailed analysis of water transport mechanism in starch gels.

Proceedings of the 12th International Conference on Polysacch arides-Glycoscience - Czech Chemical Society, , 193-195 (2016)


ISBN: 978-80-86238-59-3   (Pobrane:  2017-11-06)

32.

Kuźnik N., Tomczyk M.M., Boncel S., Herman A.P., Kozioł K.K., Kempka M.

Fe3+ ions anchored to Fe@O - MWCNTs as double impact T2 MRI contrast agents Fe3+ ions were anchored via complexation onto the oxidized multiwall carbon nanotubes containing encapsulated iron-based nanoparticles (Fe@O-MWCNTs) yielding hybrids Fe(III)/Fe@O-MWCNTs for application as MRI contrast agents. After washing, no free Fe3+ ions were observed in the solution. A 120 mg Fe3+ was coordinated by each 1 gram of Fe@O-MWCNTs with a formation of stable hybrids. Relaxation times T1 and T2 of water protons were measured for the suspensions of hybrids. At 7.1 T relaxivity, r2 of Fe@O-MWCNT and Fe(III)/Fe@O-MWCNT was 25 and 35 s(-1) ml mg(-1), respectively, whereas at 0.4 T r2-values were equal. Additionally, T1/T2 ratio was found in a range of 17-104, which is a promising value in the light of application of the proposed materials as potential T2 MRI contrast agents.
(C) 2014 Elsevier B.V. All rights reserved.

Materials Letters, 138, 34-36 (2014)

DOI: 10.1016/j.matlet.2014.07.174

31.

Kuźnik N., Wyskocka M., Jarosz M., Oczek L., Goraus S., Komor R., Tomasz Krawczyk T., Kempka M.

Amino-phenol complexes of Fe(III) as promising T1 accelerators Iron(III) complexes with N,O-ligands are compounds of high interest because they can be applied in catalysis and play an important role in living organisms, e.g., as models of catechol dioxygenase. Several N,O-ligands were studied: their synthesis, iron(III) complexation and the potential of the latter as T1-MRI contrast agents. A route to the tetrapodal N3O2-naphthyl ligand was investigated. The resulting iron complex was obtained in 26% total yield and its relaxivity value was moderate (r1 = 1.03 in water and 2.54 s-1 mM-1 in serum). Thus, phenyl isomeric salan complexes were obtained. These complexes differed in charge (positive and neutral) and in the presence of polar hydrogen-bonding substituents. The highest relaxivities (r1 = 2.39 in water and 5.37 s-1 mM-1 in serum) were obtained for the Fe(III) cationic complex with MeO groups in the ligand. EPR studies confirmed a high spin configuration of rhombically distorted Fe(III) complexes.

Arabian Journal of Chemistry, , (2014)

DOI: 10.1016/j.arabjc.2014.11.009   (Pobrane:  2020-10-23)

30.

Dobies M., Kempka M., Kuśmia S., Jurga S.

Acid induced gelation of low methoxyl pectins studied by 1H NMR and rheological methods The various 1H NMR techniques (1H NMRD, water proton spin-spin relaxation time and diffusion measurements) in combination with rheological measurements were applied to the analysis of the acid induced gelation of 3% w/w aqueous LM pectin solutions at 279 K. A decrease of the pH value of solutions from 5 to 2.6 leads to a slowdown in the dynamics of the water molecules and to a substantial modification in the structure of the system studied. The most significant changes in the 1H NMRD and T2 measurements were observed when the pH was varied from 5 to 3, which reflected an increase in the stiffness of the pectin chains caused by non-ionic associations and by an increase of water molecules that were trapped between the pectin chains in the gelled ste. The results obtained by the rheological method are consistent with those of 1H NMR, indicating a solution-like mechanical response for the sample at pH 5 and a gel-like response at pH 3. Results of 1H NMR measurements have also shown an important role for aggregation processes of the LM pectin molecules in the acid-induced gel network formation.

Applied Magnetic Resonance, 34(1-2), 71-81 (2008)

DOI: 10.1007/s00723-008-0107-7   (Pobrane:  2020-10-21)

29.

Kozak M., Kempka M., Szpotkowski K., Jurga S.

NMR in soft materials: A study of DMPC/DHPC bicellar system The DMPC/DHPC bicellar system at the molar ratio of 2.8:1 has been characterised by measurements of self-diffusion coefficient (using PFGSE and PFGSTE NMR sequences), differential scanning calorimetry (DSC) and small angle scattering of synchrotron radiation (SAXS). The DSC curve shows only one endothermic peak characterised by the peak temperature T-peak = 295.7 K and the onset temperature T-onset = 290.1 K. This peak can be assigned to the nematic to smectic phase transition. Below the phase transition temperature, NMR diffusion experiments indicate a two-exponential decay of the spin echo amplitude allowing two diffusion coefficients D, and D-2 to be extracted from the experimental data. The maximum size (D-max) of the bicelle determined from SAXS data using the pair distance distribution function p(r) is 11.2 nm and the bilayer thickness is 5 nm.
(C) 2007 Published by Elsevier B.V.

Journal of Non-Crystalline Solids, 353(47-51), 4246-4251 (2007)

DOI: 10.1016/j.jnoncrysol.2007.02.068   (Pobrane:  2020-10-21)

28.

Garnczarska M., Zalewski T., Kempka M.

Changes in water status and water distribution in maturing lupine seeds studied by MR imaging and NMR spectroscopy The changes in water distribution in maturing lupin (Lupinus Luteus L.) seeds were visualized with magnetic resonance imaging (MRI). MRI data showed local inhomogeneities of water distribution inside the seed. At the late seed-filling stage the most intense signal was detected in the seed coat and the outer parts of cotyledons in the hilum area, but during maturation drying the decline in MR image intensity was faster in the outer part of the seed than in the central part. The changes in water status were characterized by NMR spectroscopy. Analyses of T-2 relaxation times revealed a three-component water proton system in maturing lupin seeds. Three populations of protons found during seed maturation, each with a different magnetic environment causing a different relaxation rate, were correlated with three fractions of water (structural, intracellular, and extracellular) that were observed during seed germination. This study provides evidence that lupin seeds have similar states of the different water components with regard to seed moisture content at two distinct physiological stages, seed maturation and germination. The unique feature of maturing lupin seeds is the presence of the high H-1-NMR signal in areas corresponding to the vascular bundles. Tissue localization of dehydrins showed the presence of dehydrin protein in the area of vascular tissue. An anti-dehydrin antibody detected three polypeptides in lupin embryos with molecular masses of 73, 43 and 28 kDa, respectively. The temporal pattern of dehydrin protein accumulation correlates well with seed desiccation.

Journal of Experimental Botany, 58(14), 3961-3969 (2007)

DOI: 10.1093/jxb/erm250

27.

Garnczarska M., Zalewski T., Kempka M.

Water uptake and distribution in germinating lupine seeds studied by magnetic resonance imaging and NMR spectroscopy Magnetic resonance imaging (MRI) was used to study temporal and spatial water uptake and distribution in germinating lupine (Lupinus Luteus L.) seeds. During 24 h of imbibition, water was unevenly distributed within the seed and some anatomical parts were more hydrated than others. Water entered the seed through the hilum and micropyle. The embryonic axis was the first to show hydration followed by seed coat and later cotyledons. The changes in water status were characterized by NMR spectroscopy. Analyses of T-2 relaxation times revealed a three-component water proton system (structural, intracellular and extracellular water) in germinating lupine seeds. The data on the components of transverse relaxation time studies indicated the complex exchange processes taking place between water components inside lupine seed over first 2.5 h of hydration, with a distinguished increase in structural water and decrease in other components. This speaks in favor of the high water-absorbing capacity of lupine seeds as related to high protein content. Germination was accompanied by swelling of protein bodies and changes in the organization of stored reserves with gradual disappearance of protein from the cells.

Physiologia Plantarum, 130(1), 23-32 (2007)

DOI: 10.1111/j.1399-3054.2007.00883.x

26.

Hankiewicz J., Kempka M., Fiat D.

In vivo natural-abundance 17O/1H MRI of Rhesus monkey brain with whole-body scanner and homebuilt multinuclear accessory The construction of an accessory to commercial whole-body magnetic resonance imaging (MRI) scanners that provides multinuclear capability is described. The multinuclear system has access to all clinical pulse sequences and is not limited by the frequency range of the commercially available "spectroscopic package". The accessory was used for O-17 studies with a homebuilt birdcage resonator and a low-noise preamplifier. In vivo O-17 images of a rhesus monkey brain were obtained. The homebuilt birdcage was transparent to radio-frequency irradiation of the scanner's body coil at H-1 frequency allowing consecutive acquisitions of H-1 and O-17 images and their superposition. The results demonstrate the potential of O-17/H-1 imaging with whole-body scanners.

Applied Magnetic Resonance, 24(3-4), 393-400 (2003)

DOI: 10.1007/BF03166941

25.

Kempka M., Hankiewicz J., Fiat D.

Combined 17O/1H MRI study in a whole-body scanner A simple method of obtaining consecutive H-1 and natural-abundance O-17 images is described with a scanner's original body resonator (for H-1) and a homemade linear birdcage (for O-17). Two kinds of experiments were performed to test the method. In the first experiment, a proton image of the phantom was acquired with a whole-body resonator. In the second experiment, the phantom was inserted into an oxygen birdcage resonator and imaged again with a whole-body resonator. The intensities of images resulting from the experiments were analyzed. Although the B-1 field homogeneity is disturbed, the proton images acquired with a whole-body resonator when the oxygen resonator is present are of acceptable quality for use in the combined O-17/H-1 imaging.

Applied Magnetic Resonance, 24(3-4), 409-415 (2003)

DOI: 10.1007/BF03166943

24.

Andrew E.R., Kempka M., Radomski J.M., Szcześniak E.

Molecular dynamics in solid anhydrous beta-estradiol studied by 1H NMR Proton second moment and spin-lattice relaxation times T-1 and T-1p in solid anhydrous beta-estradiol are measured as a function of temperature. The results show that the C-3 reorientation of the single methyl group provides the mechanism dominating relaxation at low temperatures and reveal the existence of a conformational motion of the carbon skeleton dominating relaxation at high temperatures. The activation energies of the respective motions are found to be 9.3 and 37.3 kT/mol.
(C) 1999 Elsevier Science B.V. All rights reserved.

Solid State Nuclear Magnetic Resonance, 14(2), 91-94 (1999)

DOI: 10.1016/S0926-2040(99)00009-0   (Pobrane:  2020-10-21)

23.

Andrew E.R., Kempka M.

Transverse gradient coil with circle current paths The paper describes a new type of transverse magnetic field gradient coil for applications in MRI and MRS. It uses full circle current paths rather than current arcs and has a particularly simple unit construction of symmetric form. It features a large volume of uniform transverse field gradient, high efficiency and low inductance for rapid switching. A prototype coil has been constructed and evaluated to check computer simulations. Two smaller sets have subsequently been made for NMR microscopy. This coil design may be used for all sizes.
(C) 1998 Elsevier Science BV. All rights reserved.

Magnetic Resonance Materials in Physics, Biology and Medicine - MAGMA, 7(1), 55-60 (1998)

DOI: 10.1007/BF02592257
WWW: http://link.springer.com/journal/10334   (Pobrane:  2021-01-07)

22.

Andrew E.R., Peplińska B., Kempka M.

Molecular dynamics in solid L-adrenaline by proton NMR Proton NMR measurements of the spectrum, second moment, spin-lattice relaxation time T-1 and dipolar relaxation time T-1D were carried out on polycrystalline L-adrenaline at 14 and 25 MHz between 55 and 400 K. Between 70 K and 250 K relaxation is dominated by C-3 reorientation of the single methyl group in each molecule, characterized by an activation energy 8.3 ± 0.3 kJ/mole. Below 70 K tunnelling assisted relaxation is significant, characterized by an excitation energy of 1.9 ± 0.2 kT/mole. Above 250 K an additional molecular motion becomes significant, with activation energy above 28 kT/mole, attributed to conformational motion of the methylene group in the ethylamine side chain.
(C) 1998 Elsevier Science B.V.

Solid State Nuclear Magnetic Resonance, 10(3), 117-121 (1998)

DOI: 10.1016/S0926-2040(97)00077-5   (Pobrane:  2020-10-25)

21.

Andrew E.R., Kempka M., Sagnowski S., Szcześniak E.

Autorstwo lub wspólautorstwo książki, podręcznika akademickiego, monografii, zeszytów ćwiczeń i innych materiałów dydaktycznych, a także redakcja edytorska, słowo wstępne,
w wydawnictwach naukowych ISSN lub ISBN,
oraz w wydawnictwach popularno - naukowych.

Novel gradient coils for magnetic resonance microscopy This paper describes three magnetic field gradient coils of considerable simplicity, two for transverse gradient and one for longitudinal gradients. The coaxial arc gradient coil has a simple unit construction of symmetric form. It features a large volume of uniform transverse field gradient, high efficiency and low inductance rapid switching. A prototype coil was first constructed and a smaller coil set was [hen constructed for NMR microscopy, with excellent results. The system may be used for all sizes from microimaging to whole-body MRI. The second transverse gradient coil uses full circle current paths rather than current arcs. It has an even simpler form of construction and has closely similar properties to the coaxial arc transverse gradient coil. A prototype coil set was first made and two smaller coil sets have been made for NMR. microscopy. The longitudinal gradient coil is based on an analysis of the multipole expansion of the external field of a gradient coil system. It is first shown that a Maxwell pair has no hexadecapole moment. The field outside such a pair therefore falls as r-4 from the quad-rupole moment and as r-8 from the 64-pole moment. Using a nested pair of Maxwell pairs the quadrupole term is canceled leaving only the rapid attenuation of the r-8 term, thus providing a simple screened Longitudinal gradient coil.

Spatially Resolved Magnetic Resonance, Eds. Blumler P., Blumich B., Botto R., Fukushima E., WILEY-VCH, Weinheim, New York, Chichester, Brisbane, Singapore, Toronto, , 683-693 (1998)

WWW: http://onlinelibrary.wiley.com/book/10.1002/9783527611843
ISBN: 9783527296378   (Pobrane:  2023-03-27)

20.

Andrew E.R., Kempka M., Szcześniak E.

Novel transverse gradient coils for magnetic resonance microimaging

IV International Conference on Magnetic Resonance Microscopy and Macroscopy, Albuquerque (New Mexico / USA), , 52 (1997)

19.

Buszko M.L., Kempka M.F., Szcześniak E., Wang D.C., Andrew E.R.

Optimization of transverse gradient coils with coaxial return paths by simulated annealing Coils with coaxial return paths are used to generate transverse magnetic field gradients. This paper describes optimization of such coils by the method of simulated annealing, a method known to be able to find the global minimum of a function. The adaptive simulated annealing (ASA) program has been analyzed and applied to optimization of a family of coils with 8-16 building blocks, each carrying equal current. Positions of the blocks along the longitudinal axis of the coils were optimized. A new subclass of coils is proposed; the diameter of return paths of this subclass of coils is not fixed but may be varied, The new coils provide greater gradient uniformity than those for which only positions of the blocks are optimized, All optimized coils should find applications in high-precision and high-resolution imaging and spectroscopic experiments.
(C) 1996 Academic Press, Inc.

Journal of Magnetic Resonance Series B, 112(3), 207-213 (1996)

DOI: 10.1006/jmrb.1996.0133   (Pobrane:  2020-10-21)

18.

Andrew E.R., Kempka M., Szyczewski A.

Molecular dynamics of solid cortisol studied by NMR Polycrystalline cortisol (hydrocortisone; 11 beta,17 alpha,21-trihydroxy-4-pregnene-3,20-dione; C21H30O5) has been investigated by continuous and pulse proton NMR methods between 78 and 400 K at Larmor frequencies of 7, 25 and 60 MHz. A reduced value of second moment was found above 90 K and is ascribed to reorientation of two methyl groups. A single asymmetric minimum was found in the temperature dependence of the spin-lattice relaxation times and this also is attributed to reorientation of two methyl groups. The asymmetry suggests an asymmetric distribution of correlation times of the motion. Using the Cole-Davidson distribution, the best computer fit yields the following parameters characterizing the motion: E(s) = 11.8 ±0.1 kJ mol(-1), tau(0) = 4.6 ±0.4) x 10(-13) s, distribution parameter delta = 0.62.

Molecular Physics, 88(3), 605-610 (1996)

DOI: 10.1080/00268979650026154

17.

Andrew E.R., Inglis B.A., Kempka M., Mareci T.H., Szcześniak E.

Magnetic field gradient system for nuclear magnetic resonance microimaging In this study we present an orthogonal magnetic field gradient system for nuclear magnetic resonance (NMR) microimaging applications. The construction details are given for a prototype assembly for proton microscopy inside a 50-mm vertical bore magnet, which is designed to fit into a commercial 300-MHz NMR probe. This system has been used to acquire images of the human spinal cord in vitro. Its performance has been evaluated and compared to that predicted by computer simulation.

Magnetic Resonance Materials in Physics Biology and Medicine - MAGMA, 4(24), 85-91 (1996)

DOI: 10.1007/BF01772515   (Pobrane:  2021-01-07)

16.

Andrew E.R., Kempka M.

Molecular motions in solid estradiol studied by nuclear magnetic resonance spectroscopy The temperature dependence of the proton nuclear magnetic resonance (NMR) relaxation time T-1 and second moment M(2) of polycrystalline beta-estradiol hemihydrate (1,3,5-estratriene-3,17 beta-diol) is measured at frequencies of 14 and 25 MHz. Below 260 K relaxation is found to be dominated by C-3 reorientation of the single methyl group in each molecule, characterized by an activation energy of 9.4 ±0.1 kJ/mol. Above 260 K another relaxation mechanism becomes evident, characterized by an activation energy of 22.0 ±2.0 kJ/mol and ascribed to motion of the water molecules in the solid.

Solid State Nuclear Magnetic Resonance, 4(4), 249-253 (1995)

DOI: 10.1016/0926-2040(95)00003-9

15.

Suchański W., Peplińska B., Kempka M.

Magnetic relaxation and anisotropic molecular reorientation of liquid 3-acetylpyridine The nuclear spin-lattice relaxation times of C-13 and N-14 as well as the nuclear Overhauser enhancement factor have been measured as a function of temperature for liquid 3-acetylpyridine. Principal components of the relational diffusion tenser have been determined. The results are discussed in terms of relative influence of molecular shape and attractive dipolar forces on anisotropy of the molecular reorientations.

Berichte der Bunsengesellschaft/Physical Chemistry Chemical Physics, 99(4), 595-599 (1995)

DOI: 10.1002/bbpc.19950990402

14.

Buszko M.L., Kempka M., Szcześniak E., Wang D.C., Andrew E.R.

Application of adaptive simulated annealing to optimization of gradient coils with concentric return paths

12th Conference of the International Society of Magnetic Resonance, ISMAR, T28, Sydney (Australia), , 95 (1995)

13.

Andrew E.R., Inglis B.A., Kempka M., Mareci T.H., Szcześniak E.

A compact low inductance transverse gradient system for magnetic resonance microscopy. Application to the human spinal cord

3rd International Conference on Magnetic Resonance Microscopy, Wurzburg (Germany), , (1995)

12.

Buszko M.L., Kempka M., Szcześniak E., Wang D.C., Andrew E.R.

Optimization of transverse gradient coils with concentric return paths by simulated annealing

36th Experimental Nuclear Magnetic Resonance Conference, Boston (USA), , 360 (1995)

11.

Suchański W., Peplińska B., Kempka M.

Anizotropia reorientacji w molekułach pierścieniowych

Raport IBJ, Kraków, 1695/PL, 189 (1995)

WWW: http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/29/024/29024462.pdf

10.

Suchański W., Kempka M., Peplińska B., Pająk Z.

Magnetic relaxation and molecular motions in liquid 3,5-dimethylpyridine The nuclear spin-lattice relaxation times of N-14 have been measured as a function of temperature for liquid 3,5-dimethylpyridine. These results together with the values of the C-13 spin-lattice relaxation times and the factor of nuclear Overhauser enhancement for the ring C2,6 and C4 carbons presented previously [15], have been analyzed in terms of relative influence of molecular shape and attractive dipolar forces on anisotropy of the molecular reorientations. Principal components of the rotational diffusion tensor have been determined.

Berichte der Bunsengesellschaft/Physical Chemistry Chemical Physics, 98(6), 804-808 (1994)

DOI: 10.1002/bbpc.19940980607

9.

Suchański W., Kempka M., Peplińska B., Pająk Z.

Anisotropy of motions in derivatives of pyridine

Raport IBJ, Kraków, 1658/PL, 189 (1994)

8.

Kempka M, Peplińska B, Pająk Z.

Proton NMR study of molecular motion in solid cortisone Polycrystalline cortisone (17,21-dihydroxy-4-pregnene-3,11,20-trione, C21H28O5) has been investigated by proton NMR methods between 56 and 400 K at 14 and 25 MHz. Reductions in second moment and two very well-resolved minima in the spin-lattice relaxation time at both frequencies are attributed to reorientation of the two methyl groups on carbons 18 and 19. The data are very well fitted over the entire temperature range to the Kubo-Tomita dipolar relaxation theory using the same parameters at both frequencies. Activation energies Ea characterizing the hindrances to the two methyl reorientations were 5.9 and 15.5 kJ/mol, an unusually large difference. The relaxation constants were 6.4 and 7.9 × 108 s-2.

Solid State Nuclear Magnetic Resonance, 2(5), 261-264 (1993)

DOI: 10.1016/0926-2040(93)90006-9

7.

Suchański W., Kempka M., Peplińska B., Pająk Z.

NMR and molecular anisotropic motion in 3 acetylpyridine

Proccedings of 15th Conference on Radio and Microwave Spectroscopy, Poznań (Poland), , 93-94 (1993)

6.

Grochulski T., Pszczółkowski L., Kempka M.

Applicability of extended hydrodynamical model to dielectric-relaxation in simple polar liquids Dielectric relaxation profiles and self-diffusion coefficients were measured for 1,1,1-trichloroethane, t-butyl chloride, and 2,2-dinitropropane in liquid and plastic phases. For all three samples no significant change in the relaxational behavior is observed when going from liquid to plastic-crystal phases. The comparison of the results with the extended hydrodynamic model shows that the model overestimates the effect of translational-rotational coupling on dielectric properties of liquids.

Physical Review Letters, 68(24), 3635-3637 (1992)

DOI: 10.1103/PhysRevLett.68.3635

5.

Suchański W., Kempka M., Peplińska B., Pająk Z.

Magnetic relaxation and molecular anisotropic rotational motion in liquid 3,5 dimethylpyridine

Proccedings of 26th Congres Ampere on Magnetic Resonance, Athens (Greece), , 596 (1992)

4.

Andrew E.R., Buszko M.L., Kempka M., Peplińska B.

NMR studies of polycrystalline cholesterol, cortisone and lactic acid

Proccedings of British Radiofrequency Spectroscopy Group: Molecular Motion and Structure in Disordered Condensed Matter, Exeter (United Kingdom), , 271 (1991)

3.

Kempka M, Peplińska B, Pająk Z.

Anisotropy of translational diffusion in liquid alpha, omega-dibromoalkanes The analysis of the measured temperature dependences of self-diffusion coefficients for prolate ellipsoid type molecules of α,ω-dibromo-methane, -ethane, -octane, -decane and -dodecane performed in the frame of the modified Perrin model enabled to discover anisotropy of translational diffusion in liquids. On the basis of the Eyring theory the effect was confirmed and the jump length of about 7 A for all the molecules was derived. The same jump length for longer molecules was obtained from the Cohen-Turnbull free volume theory.

Berichte der Bunsengesellschaft fur Physikalische Chemie, 92(6), 686-689 (1988)

DOI: 10.1002/bbpc.198800172

2.

Kempka M., Peplińska B., Pająk Z.

Translational diffusion in the liquid state of camphene and tolane

IBJ Kraków, Raport , No 1404/Pl, 170 (1988)

1.

Kempka M., Peplińska B., Pająk Z.

Self diffusion in alpha, omega dibromoalkanes

IBJ Kraków, Raport , No 1364/Pl, 37 (1987)

 © Opisy i zdjęcia: Zakład Fizyki Makromolekularnej  | Ta stona używa ciasteczek
     Zaktualizowano: podstrony  2021-06-21  / bazę danych:   2023-10-06  by Webmaster: Zbigniew Fojud