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od 2020-09-20 |
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1. |
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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. |
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Materials Letters, 138, 34-36, (2014) |
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2. |
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Intrinsically Disordered and Pliable Starmaker-Like Protein from Medaka (Oryzias latipes) Controls the Formation of Calcium Carbonate Crystals Fish otoliths, biominerals composed of calcium carbonate with a small amount of organic matrix, are involved in the functioning of the inner ear. Starmaker (Stm) from zebrafish (Danio rerio) was the first protein found to be capable of controlling the formation of otoliths. Recently, a gene was identified encoding the Starmaker-like (Stm-l) protein from medaka (Oryzias latipes), a putative homologue of Stm and human dentine sialophosphoprotein. Although there is no sequence similarity between Stm-l and Stm, Stm-l was suggested to be involved in the biomineralization of otoliths, as had been observed for Stm even before. The molecular properties and functioning of Stm-l as a putative regulatory protein in otolith formation have not been characterized yet. A comprehensive biochemical and biophysical analysis of recombinant Stm-l, along with in silico examinations, indicated that Stm-l exhibits properties of a coil-like intrinsically disordered protein. Stm-l possesses an elongated and pliable structure that is able to adopt a more ordered and rigid conformation under the influence of different factors. An in vitro assay of the biomineralization activity of Stm-l indicated that Stm-l affected the size, shape and number of calcium carbonate crystals. The functional significance of intrinsically disordered properties of Stm-l and the possible role of this protein in controlling the formation of calcium carbonate crystals is discussed.
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PLoS ONE, 9(12), (2014) |
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Facile synthesis of highly stable and water-soluble magnetic MWCNT/alpha-Fe nanocomposites Multiwall carbon nanotubes (MWCNT) were synthesized by the floating catalyst chemical vapor deposition (FCCVD) method. As a result, nanotubes containing metallic iron (a-Fe) were obtained and characterized. The impact of surface modification, on MWCNTs stability in water, was thoroughly studied applying three oxidative protocols. Samples were further characterized and correlated based on scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA), and the magnetic nature of the embedded nanoparticles was assessed by means of a SQUID magnetometer at room temperature in powder. Finally, precise length segregation of MWCNT/alpha-Fe nanocomposites was achieved. The studied structures showed excellent quality and unmatched stability in water after more than three months.
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The Journal of Physical Chemistry C, 118(4), 27861-27869, (2014) |
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Structural, spectroscopic and magnetic properties of Eu3+ - doped GdVO4 nanocrystals synthesized by a hydrothermal method New interesting aspects of the spectroscopic properties, magnetism, and method of synthesis of gadolinium orthovanadates doped with Eu3+ ions are discussed. Gd-1-xEuxVO(4) (x = 0, 0.05, 0.2) bifunctional luminescent materials with complex magnetic properties were synthesized by a microwave-assisted hydrothermal method. Products were formed in situ without previous precipitation. The crystal structures and morphologies of the obtained nanomaterials were analyzed by X-ray diffraction and transmission and scanning electron microscopy. Crystallographic data were analyzed using Rietveld refinement. The products obtained were nanocrystalline with average grain sizes of 70-80 nm. The qualitative and quantitative elemental composition as well as mapping of the nanocrystals was proved using energy-dispersive X-ray spectroscopy. The spectroscopic properties of red-emitting nanophosphors were characterized by their excitation and emission spectra and luminescence decays. Magnetic measurements were performed by means of vibrating sample magnetometry. GdVO4 and Gd0.8Eu0.2VO4 exhibited paramagnetic behavior with a weak influence of antiferromagnetic couplings between rare-earth ions. In the substituted sample, an additional magnetic contribution connected with the population of low-lying excited states of europium was observed.
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Inorganic Chemistry, 53(23), 12243-12252, (2014) |
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Physical properties of the InPd intermetallic catalyst The intermetallic phase InPd is a candidate material for the use as a catalyst in the methanol steam reforming process. To study the connection between the catalytic properties of the surface and the structural and electronic properties of the bulk, we have grown single crystals of the InPd phase by the Czochralski method and determined their electronic, thermal, magnetic and hydrogen-absorption properties. By growing crystals from a high-temperature solution, we could crystallize a slightly off-stoichiometric In-rich composition In1.04Pd0.96, which contained a significant amount of constitutional defects in the lattice (Pd vacancies on the Pd sublattice) to retain the CsCl-type structure. The strongly inhomogeneously broadened In-115 NMR spectrum and the high residual (T -> 0) electrical resistivity confirmed the presence of constitutional defects. Single crystals of InPd do not absorb hydrogen, as requested for a good hydrogenation catalyst material. Calculated electronic density of states (DOS) shows large contribution of Pd(d) states at the Fermi level. Application of the electron localizability indicator reveals ionic and multi-centre In Pd interactions stabilizing the crystal structure. The electrical and thermal conductivities of InPd show metallic character, whereas the thermoelectric power and the Hall coefficient both show positive sign, revealing that InPd is a predominant hole-type conductor. The calculated electronic DOS at the Fermi energy is in a good agreement with the experimental value determined from the low-temperature specific heat. Magnetic measurements have shown that InPd is a diamagnet. All results are compared to the chemically related intermetallic compound GaPd. The active site-isolation concept for increased catalytic selectivity is discussed in relation to the InPd and GaPd structures.
(C) 2014 Elsevier Ltd. All rights reserved. |
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Intermetallics, 55, 56-65, (2014) |
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6. |
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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.
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Arabian Journal of Chemistry, (2014) |
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7. |
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Acta Physica Polonica A, 125(5), 1236-1239 , (2014) |
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8. |
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Identification of multiple sclerosis cerebrospinal fluid biomarkers using nuclear magnetic resonance spectroscopy Nuclear Magnetic Resonance (NMR) spectroscopy identifies metabolites of small molecular weight present in cerebrospinal fluid (CSF). Diagnosis of multiple sclerosis (MS) and clinically isolated syndrome (CIS) is based on a combination of symptoms, laboratory tests and MRI results, and sometimes is not conclusive especially early in the disease process. Previous studies that employed NMR to examine the CSF of patients with CIS and MS focused mainly on differences and did not use receiver operator characteristics (ROC) curves statistics to assess the peaks. Additionaly they usually involved sample pH adjustment that could influence the metabolites and their stability.
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Multiple Sclerosis Journal, 20(1), P265-186, (2014) |
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9. |
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The FEBS Journal, 281, 647, (2014) |
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10. |
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Dynamic glass transition and electrical conductivity behavior dominated by proton hopping mechanism studied in the family of hyperbranched bis-MPA polyesters Dielectric and infrared spectroscopies were employed to study inter- and intramolecular glass-transition dynamics in the series of hyperbranched polyesters of the second, third, and fourth generations. Our study shows that conductivity relaxation becomes increasingly faster than structural relaxation as the glass transition temperature Tg is approached, signifying decoupling between translational motions of charges and reorientation of molecules. Depending on the polymer's generation conductivity relaxation times can be up to few orders of magnitude faster than structural dynamics. Because of extensive hydrogen bonding network, the most significant contribution to the total ionic conductivity comes from proton transfer along hydrogen bonds. Decoupling phenomenon was accompanied by narrowing the dispersion of the conductivity relaxation with decreasing temperature that reaches almost exponential decay in the glassy state. Finally, by analyzing the absorption spectra in terms of integral intensity, we have demonstrated significant role of H-bonded moieties in the course of vitrification of investigated materials.
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Macromolecules, 47(16), 5798-5807, (2014) |
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11. |
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Structural and spectroscopic studies on the formation of lipoplexes between DNA and cationic gemini surfactants The process of complex formation between cationic gemini surfactants, 3,3'-[α,ω-(dioxaalkane)]bis(1-dodecylimidazolium) dichloride, with deoxyribonucleic acid (DNA) was studied. The study was performed for ten surfactants having spacer groups of different lengths used in 6 concentrations (5 mM, 2 mM, 1 mM, 0.5 mM, 0.2 mM, 0.1 mM) and a 6.5 μM DNA solution. The complex formation was verified by circular dichroism spectroscopy and gel electrophoresis. The complexes were found to be stable and the process of complex formation was reproducible, efficient and immediate.
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Polimery/Polymers, 59(7-8), 569-574, (2014) |
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12. |
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Interaction of Bovine Serum Albumin (BSA) with novel gemini surfactants studied by synchrotron radiation scattering (SR-SAXS), circular dichroism (CD) and nuclear magnetic resonance (NMR) The interaction of three dicationic (gemini) surfactants-3,3'-[1,6-(2,5-dioxahexane)]bis(1-dodecylimidazolium) chloride (oxyC2), 3,3'-[1,16-(2,15-dioxahexadecane)]bis(1-dodecylimidazolium) chloride (oxyC12), and 1,4-bis(butane)imidazole-1-yl-3-dodecylimidazolium chloride (C4)-with bovine serum albumin (BSA) has been studied by the use of small-angle X-ray scattering (SAXS), circular dichroism (CD), and H-1 nuclear magnetic resonance diffusometry. The results of CD studies show that the conformation of BSA was changed dramatically in the presence of all studied surfactants. The greater decrease (from 56 to 24%) in the alpha-helical structure of BSA was observed for oxyC2 surfactant. The radii of gyration estimated from SAXS data varied between 3 and 26 nm for the BSA/oxyC2 and BSA/oxyC12 systems. The hydrodynamic radius of the BSA/surfactant system estimated from NMR diffusometry varies between 5 and 11 nm for BSA/oxyC2 and 5 and 8 nm for BSA/oxyC12.
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Journal of Physical Chemistry B, 118(29), 8652-8661, (2014) |
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13. |
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Experimental and solid-state computational study of structural and dynamic properties in the equilibrium form of temazepam Structural properties and rotational dynamics of methyl groups in the most stable form of temazepam were investigated by means of C-13 CP MAS NMR, quasielastic neutron scattering (QENS), and H-1 NMR spin lattice relaxation methods. The QENS and H-1 NMR studies reveal the inequivalency of methyl groups, delivering their activation parameters. The structural properties of the system were explored in frame of periodic density functional theory (DFT) computations, giving insight into the reorientational barriers and providing understanding of the solid-state NMR results. The theoretical computations are shedding light on the intermolecular interactions along their relation with particular asymmetric structural units.
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Journal of Physical Chemistry B, 118(24), 6670-6679, (2014) |
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14. |
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Influence of fluorine substituents on the NMR properties of phenylboronic acids The paper presents results of a systematic NMR studies on fluorinated phenylboronic acids. All possible derivatives were studied. The experimental H-1, C-13, F-19, B-11, and O-17 spectral data were compared with the results of theoretical calculations. The relation between the calculated natural bond orbital parameters and spectral data (chemical shifts and coupling constants) is discussed. The first examples of B-10/B-11 isotopic effect on the F-19 spectra and (4)J(FO) scalar coupling in organic compounds are reported.
Copyright (C) 2014 John Wiley & Sons, Ltd. |
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Magnetic Resonance in Chemistry, 52(5), 202-213, (2014) |
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15. |
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Raman spectroscopy of nanostructured silicon fabricated by metal-assisted chemical etching In this work, we present a detailed experimental Raman investigation of nanostructured silicon films prepared by metal-assisted chemical etching with different nanocrystal sizes and structures. Interpretation of observed one and two-phonon Raman peaks are presented. First-order Raman peak has a small redshift and broadening. This phenomenon is analyzed in the framework of the phonon confinement model. Second-order Raman peaks were found to be shifted and broadened in comparison to those in the bulk silicon. The peak shift and broadening of two-phonon Raman scattering relates to phonon confinement and disorder. A broad Raman peak between 900-1100 cm(-1) corresponds to superposition of three transverse optical phonons similar to 2TO (X), 2TO (W) and 2TO (L). Influence of excitation wavelength on intensity redistribution of two-phonon Raman scattering components (2TO) is demonstrated and preliminary theoretical explanation of this observation is presented.
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Proceedings of SPIE - Optical Micro- and Nanometrology V, 9132, 913217, (2014) |
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16. |
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Low-resolution structure of the full-length barley (Hordeum Vulgare) SGT1 protein in solution, obtained using small-angle X-ray scattering SGT1 is an evolutionarily conserved eukaryotic protein involved in many important cellular processes. In plants, SGT1 is involved in resistance to disease. In a low ionic strength environment, the SGT1 protein tends to form dimers. The protein consists of three structurally independent domains (the tetratricopeptide repeats domain (TPR), the CHORD-and SGT1-containing domain (CS), and the SGT1-specific domain (SGS)), and two less conserved variable regions (VR1 and VR2). In the present study, we provide the low-resolution structure of the barley (Hordeum vulgare) SGT1 protein in solution and its dimer/monomer equilibrium using small-angle scattering of synchrotron radiation, ab-initio modeling and circular dichroism spectroscopy. The multivariate curve resolution least-square method (MCR-ALS) was applied to separate the scattering data of the monomeric and dimeric species from a complex mixture. The models of the barley SGT1 dimer and monomer were formulated using rigid body modeling with ab-initio structure prediction. Both oligomeric forms of barley SGT1 have elongated shapes with unfolded inter-domain regions. Circular dichroism spectroscopy confirmed that the barley SGT1 protein had a modular architecture, with an alpha-helical TPR domain, a beta-sheet sandwich CS domain, and a disordered SGS domain separated by VR1 and VR2 regions. Using molecular docking and ab-initio protein structure prediction, a model of dimerization of the TPR domains was proposed.
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PLoS ONE, 9(4), e93313, (2014) |
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17. |
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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.
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Physics and Chemistry of Glasses European Journal of Glass Science and Technology Part B, 55(2), 111-117, (2014) |
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18. |
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Crystal structure of active site mutant of antileukemic l-asparaginase reveals conserved zinc-binding site The periplasmic enzyme l-asparaginase type II from Escherichia coli (EcAII) converts l-asparagine to l-aspartate and ammonia. EcAII is an important drug in the treatment of childhood acute lymphoblastic leukemia, the most common malignancy in children. Leukemic blast cells lack the ability to synthesize l-asparagine and rely on other sources of l-asparagine for protein synthesis. EcAII injections deplete extracellular levels of l-asparagine, disrupting protein synthesis and inducing apoptosis in the malignant cells. The detailed mechanism of l-asparaginase catalytic action, the molecular mechanisms of its anticancer activity and the side effects associated with the treatment, including resistance to therapy, are not fully understood despite over 40 years of research. Here, we present X-ray structures of EcAII with an active site mutation, D90E, in three crystal forms. The region of the mutation is well ordered, allowing precise functional analysis of the consequences of the replacement of Asp90. In all three structures, the mutant protein exhibits an open conformation of the active site. In one of the structures, a zinc cation has been detected. The zinc cation is coordinated in a region of the protein that is implicated in the immunological response to EcAII treatment. A combined sequence-structure analysis of bacterial-type l-asparaginases reveals that the metal coordination may play a role in the response to asparaginase treatment. The observation of a zinc-binding site in antileukemic l-asparaginases provides new insight, with consequences for acute lymphoblastic leukemia therapy.
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The FEBS Journal, 281(18), 4097-4111, (2014) |
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19. |
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Nanoparticle tracking analysis of latex standardized beads The most popular technique for particle size characterization is the dynamic light scattering (DLS). In recent years new advanced method based on counting each single particle movement was introduced giving perspective for measurement of each component of mixture. This study presents some advantages of nanoparticle tracking analysis (NTA) method in comparison to DLS. For tests standard polystyrene beds were chosen vary diameter of 22, 61 and 150 nm and its mixtures. Experiments showed that the particles size resolution allows to distinguish each population in two population suspension opposed to DLS. The NTA method permits to eliminate the negative effects i.e. dust or aggregates in sample during post processing, that permits to use it in a variety of studies.
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Current Topics in Biophysics, 37, 49-53, (2014) |
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20. |
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Fabrication of size-tuneable silica particles during seed-growth process The size control is one of the most important factors during seed-growth process. Although precise determination of ingredients
concentrations is easily controllable during the growth process, there is still a possibility to synthesize oversized particles. Nanosized
fluorescent silica particles were synthetized using Stöber process and verified using three complementary methods of particle size
determination, namely Dynamic Light Scattering (DLS), Particle Tracking (PT) as well as by Transmission Electron Microscopy
(TEM) and Confocal Microscopy. The final diameter was verified by DLS and estimated to 494 nm. Parameters necessary to control
the size were derived.
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Current Topics in Biophysics, 37, 35-41, (2014) |
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21. |
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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.
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Journal of Physics: Conference Series, 554(1), 012010, (2014) |
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22. |
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Electropolymerized nanoporous polymeric SPME coatings: preparation and characterization by small angle X-ray scattering and scanning electron microscopy Polymeric polypyrrole and polythiophene solid phase microextraction (SPME) coatings were prepared using electropolymerization with a linear sweep voltammetry technique. Physicochemical properties were measured using different methods, in particular small angle X-ray scattering and scanning electron microscopy. By using innovative approaches for pore size measurement, we were able to calculate a maximum of the pore size range from 80 to 90 nm. Additionally, film thicknesses measured from 90 to 150 mu m. Using scanning electron microscopy, we describe the characteristics of polymer growth on the support surface.
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Monatshefte fur Chemie, 145(3), 527-531, (2014) |
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23. |
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Materiały do ćwiczeń ze wstępu do pracowni fizycznej: Normy ISO i matematyka w laboratorium Podręcznik dla studentów nauk przyrodniczych (zwłaszcza fizyki) w przystępny sposób przedstawia sposoby prezentacji danych pomiarowych, opracowania wyników doświadczeń laboratoryjnych i oceniania niepewności pomiarowych zgodnie z normami ISO. Wiadomości teoretyczne i praktyczne zostały zebrane w dziewięciu rozdziałach. W pierwszym opisano współczesne podejście do eksperymentu fizycznego. W rozdziale drugim przeanalizowano ocenę niepewności pomiarowych dla najczęściej używanych przyrządów pomiarowych. Rozdziały trzeci, czwarty i piąty zawierają wiedzę ze statystyki i analizy matematycznej niezbędną do oceny niepewności standardowych typu A oraz B dla pomiarów bezpośrednich i złożonych (pośrednich), a także dla parametrów uzyskanych z analizy regresji liniowej. Rozdziały szósty, siódmy i ósmy dają studentom narzędzia matematyczne do porównania wyników pomiarów (także metodą parametrycznych testów istotności), planowania dokładniejszego eksperymentu oraz dyskusji wyników i wyciągania wniosków z przeprowadzonego eksperymentu. We wszystkich wymienionych rozdziałach znajdują się rysunki obrazujące podany materiał teoretyczny i przykłady tak skonstruowane, aby pokazać, że do ich opracowania wystarcza tylko użycie prostego programu komputerowego (np. Excel), podobnie jak w laboratoriach podstaw fizyki. Ostatni rozdział zawiera, w formie protokołów, przykładowe opracowania czterech doświadczeń fizycznych (dwóch z mechaniki i dwóch z elektryczności), w których pokazano, iż rzetelne podejście do najprostszych badań eksperymentalnych pozwala wyciągnąć z nich bardzo dużo ważnych wniosków. W aneksach podano streszczenia przedstawionej wiedzy, przydatne zwłaszcza na poszczególnych etapach opracowywania wyników pomiarów. Dodano też pięć tablic statystycznych umożliwiających dokładniejsze opracowanie pomiarów niż to zalecają normy ISO.
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Wydawnictwo Naukowe Uniwersytetu im. Adama Mickiewicza, (2014) |
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Zaktualizowano: podstrony 2021-06-21 / bazę danych: 2024-11-02 by Webmaster: Zbigniew Fojud