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The structural properties of (Ba1-xSrx)PbO3 (x = 0, 0.2 and 0.6) ceramics were examined in a wide range of temperatures, from 14 K to 1223 K, using the X-ray powder diffraction method. The type of distortion of the pseudo-cubic perovskite cell was determined from the splitting of the main diffraction lines and from the analysis of the superlattice peaks. Temperature-induced structural phase transitions at high temperatures were observed. On the other hand at temperatures starting as low as 14 K, the examined ceramics did not show any phase transitions. The effect of Sr doping was evaluated and showed that with an increase in the amount of Sr2+ ions in the crystal lattice the number of SPT's decreases. Additionally, the temperatures at which these SPT's occur are shifted towards higher values. The following sequences of structural phase transitions, written using Glazer's notation, were proposed: I2/m (a-b0c-) → Ibmm (a-b0a-)→ I4/mcm (a0a0c-)→ P m 3 ¯ m (a0a0a0) for BaPbO3 I2/m (a-b0c-) → I4/mcm (a0a0c-) → P m 3 ¯ m (a0a0a0) for (Ba0.8Sr0.2)PbO3 and I2/m (a-b0c-)→ I4/mcm (a0a0c-)→ P m 3 ¯ m (a0a0a0) for (Ba0.4Sr0.6)PbO3. These SPT's were used as trial models in refinement procedures based on the Rietveld method.

Two platinum(II) coordination compounds, [PtCl(4′-R1-terpy)](SO3CF3) (1) and [PtCl(4′-R2-terpy)](SO3CF3) (2), with 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine (4′-R1-terpy) or 4′-(3-pyridyl)-2,2′:6′,2″-terpyridine (4′-R2-terpy) were synthesized and the impact of the pendant pyridyl ring on the structure and cytotoxic activity of Pt(II)-terpyridine complexes was explored. The single-crystal X-ray diffraction analysis confirmed square planar coordination of the cations [PtCl(4′-Rn-terpy)]+. The mode of binding of 1 and 2 to calf thymus DNA was examined by UV–Vis absorption titration, ethidium displacement assay and reaction with 9-ethylguanine, and the mixed covalent-intercalative mode was demonstrated. The cytotoxicity of the Pt(II) complexes against six cancer cell lines and three normal ones was determined using MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay and compared to cisplatin. The IC50 values for the compound 2 towards the cancer cell lines are in the low micromolar range. Most remarkably, 2 was over 4 times more effective than 1 and cisplatin against non-small lung adenocarcinoma (A549), and its selectivity index was ~60–80 times higher than that for 1 and cisplatin. The mechanisms underlying the loss of viability under treatment of 2 was further investigated including F-actin staining, mitotic index analysis, cytometric cell cycle analysis, Fluorescein isothiocyanate (FITC) -conjugated Annexin V antibody and propidium iodide (PI) staining, measurements of reactive oxygen species (ROS) in cells, analysis of changes in the mitochondrial mass and potential and quantitative real time polymerase chain reaction (qRT-PCR) genes analysis. The compound 2 was found to have a pro-oxidative effect by strong stimulation of cells for the production of reactive oxygen species and cytostatic effect through cell cycle arrest.

This research evaluated the suitability of synthetic photosensitizers for their use as potential photosensitizers in photodynamic therapy using steady state and time-resolved spectroscopic techniques. Four tetraphenylporphyrin derivatives were studied in ethanol and dimethyl sulfoxide. The spectroscopic properties namely electronic absorption and emission spectra, ability to generate singlet oxygen, lifetimes of the triplet state, as well as their fluorescence quantum yield were determined. Also time-correlated single photon counting method was used to precisely determine fluorescence lifetimes for all four compounds. Tested compounds exhibit high generation of singlet oxygen, low generation of fluorescence and they are chemical stable during irradiation. The studies show that the tested porphyrins satisfy the conditions of a potential drug in terms of physicochemical properties.

Powder composed of copper oxides nanoparticles with various capping agents has been synthesized and characterized with the use of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Polyvinyl alcohol (PVA), glycol propylene, glycerin and glycerin plus ammonia were used as capping agents. The scanning electron microscopy (SEM) studies showed that nanoparticles form agglomerates with the size from 80 to 120 nm while particles size determined from the XRD experiment was in the range from 7 to 21 nm. XPS and XRD experiments revealed that depending on capping and reducing agents used in the synthesis nanoparticles are composed of Cu2O, CuO or a mixture of them. The biological activity test performed for a selected sample where the capping agent was glycerin plus ammonia has shown promising killing/inhibiting behavior, very effective especially for Gram negatives bacteria.

The X-ray diffraction patterns of (Na2/3Pb1/3)(Mn1/2Nb1/2)O3 ceramics were measured within 15–850 K temperature range. The anomaly in the thermal expansion temperature dependence occurred in 250–365 K range. The generalised Cole–Cole model was proposed to describe the measured effective electric permittivity influenced by high electric conduction and the coexistence of two contributions ɛ*(T,f) = ɛ*lattice + ɛ*carriers was considered. The analysis of the electric permittivity and conduction exhibited two relaxation processes. The electric conduction relaxation characteristic time values indicated the small polaron mechanism with τ0 ≈ 10−13 s occurring in 240–345 K range and the ionic mechanism with τ0 ≈ 10−11 s involved in the other relaxation occurring in the 320–510 K range. The ionic relaxation process was ascribed to a subsystem of defects, which was weakly interrelated to the anomaly in thermal expansion of the (Na2/3Pb1/3)(Mn1/2Nb1/2)O3 ceramics. The Gate model was proposed to describe the ionic relaxation mechanism.

The molecular structure of the 5,10,15,20-tetra(1-naphthyl)porphyrin and 5,10-di(4-hexadecyloxyphenyl)-15,20-di(4-pyridyl)porphyrin were studied using high-energy X-ray diffraction (ID15-B beam line) at ESRF, Grenoble, France. The energy of the incident photons was 90.45 keV. Two-dimensional detector was used. The intensity data were converted to the pair correlation function via the Fourier transform. The theoretical pair correlation functions were simulated using the density functional theory and compared with the experimental data. Obtained results indicate that the used experimental technique together with the applied interpretation method can be regarded as efficient tools for the determination of the atomic arrangement in molecules of such kind.

Cell parameter evolution versus temperature has been established for both V 2 O 5 and MoO 3 , from 15 to 953 and 893 K, respectively. Both oxides preserve their orthorhombic crystal system and their respective space groups Pmmn and Pnma in the whole temperature range. Unusual evolution of the unit cells have been detected in these oxides and proposals are made to follow them based on detailed structural analysis. Three temperature domains have been evidenced for V 2 O 5 marked by breaks at RT and 800 K; for MoO 3 , only two domains are defined below and above 400 K. For each domain the quality of cell parameters and X-ray powder pattern indexing, have been checked by mathematical functions to buttress their coherent evolution within each temperature domain.

Photodynamic therapy (PDT) and photodynamic diagnostics (PDD) of cancer are based on the use of non-toxic dyes (photosensitisers) in combination with harmless visible light. This paper reports physicochemical properties, cell uptake, localisation as well as photodynamic efficiency of two novel lipophilic porphyrin derivatives, suitable for use as PDT sensitisers. Both compounds are characterised by high quantum yield of singlet oxygen generation which was measured by time-resolved phosphorescence. Photodynamic in vitro studies were conducted on three cancer cell lines. Results of cell survival tests showed negligible dark cytotoxicity but high phototoxicity. The results also indicate that cell death is dependent on energy dose and time following light exposure. Using confocal laser scanning microscopy both compounds were found to localise in the cytoplasm around the nucleus of the tumour cells. The mode of cell death was evaluated based on the morphological changes after differential staining. In summary, good photostability, high quantum yield of singlet oxygen and biological effectiveness indicate that the examined lipophilic porphyrin derivatives offer quite interesting prospects of photodynamic therapy application.

The Pb(Mn1/3Nb2/3)O3 ceramics has been obtained from oxides by sintering in air, using a two-stage process with precursor columbite-like (Mn0.5Nb)O3 phase. The PbO oxide was added in the second stage. Analysis of the X-ray diffraction pattern shows that the ceramics consist of 91% of major perovskite phase. A monoclinic distortion of the perovskite structure was found. The cell parameters are a = 12.193(3) A, b = 11.966(6) A, c = 12.144(2) A, β = 90°10.7′. The microanalysis made with SEM exhibited fluctuation in chemical composition of the perovskite phase. Precipitation of MnO2, PbO and the Pb–Mn–Nb–O phase different from perovskite was found. The X-ray photoelectron spectroscopy was used to study the electronic structure of the Pb(Mn1/3Nb2/3)O3 ceramics. The core levels of lead, manganese, niobium and oxygen were measured. The shape of valence band ridge is influenced by Mn 3d states. The real average chemical composition obtained from the XPS measurement is Pb0.99(Mn0.42Nb0.67)O2.92. Broadband dielectric measurement was carried out in 10−2 to 106 Hz and within 80–700 K ranges. The dominant relaxation process exhibits characteristic times typical for ionic processes τ0,H = 1 × 10−11 s for the higher temperature range and, τ0,L = 1 × 10−9 s for lower temperatures. The activation energy of relaxation process, EM,H = 0.43 eV and EM,L = 0.34 eV corresponds to activation energy of electric conductivity. The dielectric relaxation is ascribed to dipoles created by oxygen vacancies and/or Mn–VO complexes.

The (Na 0.5 Pb 0.5 )(Nb 0.5 Mn 0.5 )O 3 ceramics have been obtained from oxides by sintering in air, using a two-step process with precursor phase. Analysis of split lines in the XRD spectra allowed the determination of the crystallographic system of the solid solution, which consisted of one phase. The monoclinic space group P2 1 / m was identified. Cell parameters are a = 11.303(2) A, b = 11.536(2) A, c = 11.225(2) A, β = 88.71(2)°, V = 1463.4(4) A 3 . The high-value dielectric permittivity shows frequency dispersion in temperature characteristics. Electric modulus formalism distinguishes two relaxation processes. One is characterized with energy activation E τ , A = 0.36 eV and conductivity relaxation characteristic time τ 0, A = 1 × 10 −12 s. The other with E τ , B = 0.42 eV and characteristic time τ 0, B = 2 × 10 −11 s. They were attributed to oxygen ions jumping between vacancies V O or Mn– V O complexes. Ionic conductivity is postulated for high temperature. Variable range hopping (vrh) small polaron conductivity manifests below 220 K. Density of states at the Fermi level, N ( E F ) was estimated as 1.6 × 10 19 eV −1 cm −3 using the vrh model.

New (Na 0.5 Pb 0.5 )(Nb 0.5 Mn 0.5 )O 3 ceramics have been obtained from oxides by sintering in air, using a two-step process with precursor phase. The ceramics showed a perovskite phase (98%) with symmetry identified as monoclinic space group P 2 1 / m . The cell parameters were: a = 11.195(2) A, b = 11.249(1) A, c = 11.303(2) A, β = 89.77(1) 0 , V = 1423.2(3) A 3 . XPS examination of the compound allowed it to estimate the average composition as (Na 0.90 Pb 0.55 )(Mn 0.32 Nb 0.53 )O 2.70 . The SEM analysis showed the real distribution of the atoms within the perovskite phase. Precipitates of lead, sodium and manganese oxides were found. The valence band consisted of O 2p states hybridized with Nb 4d states containing an admixture of Mn 3d and Pb 6p states. A mixed ionic and covalent character of the bonds was found from the chemical shift. The presence of oxygen vacancies was deduced from the electric conductivity, characterized by an activation energy equal to 0.37 and 0.48 eV.

The program of the 3-year licentiate studies in econophysics is presented. We discuss details of the program and prospects for graduates. Some aspects of our cooperation with ING-Bank Śla¸ski concerning the program of these studies and its realization are also given.

The structural and vibrational properties of above mentioned crystals were determined using X-ray powder diffraction and Raman scattering experiments. At room temperature hydrate layered perovskites: Rb{sub 2}MnF{sub 5}{center_dot}H{sub 2}O and K{sub 2}FeF{sub 5}{center_dot}H{sub 2}O exhibit orthorhombic--Cmcm (D{sub 2h}{sup 17}) and monoclinic--C2/c (C{sub 2h}{sup 6}) symmetry. Their structure is built up of MnF{sub 6} or FeF{sub 5}{center_dot}H{sub 2}O octahedra forming trans-linked zig-zag chains or hydrogen bonded zig-zag chains along the major crystallographic direction [0 0 1], respectively. To confirm crystal structures and to describe lattice dynamics of these compounds the vibrational normal modes (in {gamma} point of first Brillouin zone) were calculated on the base of the group theory analysis and compared with the spectra obtained from Raman scattering experiments. A relatively good reliability was obtained for both X-ray powder diffraction and Raman scattering.

We describe our study of ballistic transport in nanostructures of lead telluride, PbTe. Submicron devices have been fabricated by electron beam lithography and chemical etching of 50 nm wide PbTe single quantum wells embedded between Pb 0.92 Eu 0.08 Te barriers grown by MBE on BaF 2 . The electron concentration in the devices was tuned by the gate voltage applied across an interfacial p–n junction. The most important observation was zero-magnetic field conductance quantization (in multiplies of 2 e 2 / h ) in narrow constrictions of dimensions comparable to electron mean free path calculated from transport mobility. This indicates considerable relaxation of requirements for quantum ballistic transport in comparison with other materials. We argue that the huge static dielectric constant of PbTe ( e 0 =1350 at 4.2 K ) leads to suppression of the long-range Coulomb potentials of charged impurities and, thus, provides favorable conditions for the conductance quantization.

The optical excitation and luminescence spectra of (Pr3+,Ce3+) ions in KCaF3 are presented. High-resolution excitation and emission spectra of Pr3+ and Ce3+ were measured at temperatures between 77 and 293 K. First measurements of KCaF3 : Ce3+ crystal show that there are nonequivalent Ce3+ centers which radiate either in UV or visible range. The major Ce3+ nonequivalent center in KCaF3 is Ce3+ ion in the site with tetragonal site symmetry (S4). Energy levels for the 4f2 ground configuration of Pr3+ in KCaF3 were established from excitation and fluorescence spectra. Energy levels assignments were made assuming electric-dipole transition selection rules for S4 site symmetry. Twenty-seven energy levels in the lowest six multiplets of the ground configuration were established. In the analysis of experimental data, the Oh magnetic-dipole selection rules were also considered to explain missing or weak transitions which are allowed in S4. Spectra of Pr3+ in KCaF3 have been analyzed with a crystal-field Hamiltonians of S4 or Oh symmetries including J mixing effects. Crystal-field parameters in these Hamiltonians have been determined by the minimization the RMS deviation between calculated and experimental energy Stark levels. We conclude that both model calculations in the S4 and Oh site symmetries for Pr3+ in KCaF3, provide the basis for a consistently good correlation with data.

It is known that the spectroscopic properties of 3d impurities in crystals are very sensitive to the environment of the ion and can be changed considerably by using different matrices. The crystal structure of KCaF3 has been previously determined by the Rietveld profile method. At room temperature, KCa1−xMnxF3 (x

The structure of a series of activated carbon materials prepared from a polymer of phenol formaldehyde resin with different degree of “burn-off” from 0 to 32% and variable porosity has been studied by wide-angle neutron scattering. The intensity measurements, extended to Q values of 50 A−1 yielded the radial distribution functions with the real space resolution of about 0.12 A. The obtained results show that the structural features of the investigated materials are not affected by the activation process. All well-defined peaks of the radial distribution functions can be reproduced by the model consisting of the defective graphite-like layers with weak inter-layer correlations.

The cubic-to-tetragonal phase transition in the mixed perovskite K{sub 1{minus}x}Li{sub x}MnF{sub 3} (x < 0.036) was investigated by single-crystal X-ray diffraction. Results of the structure refinement at 298 and 145 K are discussed. They confirm the cubic symmetry, the space group Pm3m, of the room temperature phase with strongly anisotropic thermal vibration amplitudes of the F atoms, which were also observed in the parent KMnF{sub 3}. Substitutional lattice imperfections at the K{sup +} sites shift the ferrodistortive phase transition to higher temperature T{sub c1} = 191 K, compared to 186.5 K in KMnF{sub 3}. The structural changes in the tetragonal phase (I4/mcm) are characterized by the displacements of the F atoms from the positions they occupy above T{sub cl}. However, the Li{sup +} ion dopants do not affect the octahedral network, the MnF{sub 6} octahedra remain regular, and no displacements of K{sup +}/Li{sup +} cations along the tetragonal c axis are observed. The thermodynamic character of the transition is illustrated with the critical behavior of the unit cell parameters and the temperature-dependent evolution of the tetragonal deformation and the macroscopic strain. A variation of the integrated intensity of superstructure reflections close to T{sub cl} has been assumed to describe themore » behavior of the order parameter. As far as the precision of the present experiment allows, all these observations show that 3.6% Li{sup +} substitution at the K{sup +} site does not radically change the nature of the transition in KMnF{sub 3} at T{sub cl}.« less

We have studied the structural and magnetic properties of the Me 2 [Fe(CN) 6 ] family. The X-ray measurements were carried out at room temperature and the magnetic studies in the temperature range 4.2–260 K using static magnetic fields up to 12 T. From the X-ray analysis results the compounds crystallize in the face-centered cubic structure with the space group F43m. Both the Fe and Me ions are coordinated octahedrally by six carbon atoms and six nitrogen atoms, respectively. The Fe ions are in a strong crystalline field and the Me ions in an intermediate one of cubic symmetry. From the magnetization versus temperature curves we obtain the critical temperatures, the Curie-Weiss temperatures, the Curie constants, as well as the effective moments in the paramagnetic state. From the field dependence of the magnetization we determine the saturation magnetization and the high-field susceptibility. The data suggest that only the divalent Me cations are magnetic and coupled ferromagnetically between each other. The magnetic properties of the compounds were analyzed in the framework of the mean field theory.

Unit-cell parameters of KMnF3 single crystals have been measured by X-ray diffraction under hydrostatic pressure up to 9.5 GPa in a diamond-anvil cell. A cubic/tetragonal structural phase transition has been observed at Pc = 3.1 GPa. The tetragonal phase was stable to the upper limit of the measured pressure range (P = 10.0 GPa) and a linear pressure dependence of the macroscopic spontaneous strain ϵs above Pc has been shown. The linear and volume compressibilities of both phases have been calculated.

X-ray analysis of a new hexacyanoferrate family showed that compounds with Me′=Cu, Mn, Co, Ni and Cr crystallize in a disordered cubic structure with space group F 4 3m and the compound with Me′ =KMn crystallizes in a monoclinic structure with space group P2 1 /c. Compounds with Me′=Cu, Mn, Co and Ni are ferromagnets, the compound with Me′=Cr is a ferrimagnet and that with Me′=KMn is an antiferromagnet.