Platinum was introduced to poly(4-vinylpyridine) (P4VP) using aqueous H2PtCl6 solution of pH 1.8. Several techniques (FTIR, Raman and X-ray photoelectron spectroscopy, extended X-ray absorption fine structure, X-ray diffraction, scanning electron microscopy) have been used to characterize the state of platinum species in Pt/P4VP composites. They showed incorporation of platinum mostly in the form of counterions, anionic complexes of Pt(IV) like [PtCl6]2− in which Cl− ligands predominated. Pyridinic-N of P4VP participates in the coordination of Pt(IV) species, however to definitively lower extent. Reduction of as-prepared Pt/P4VP composites by NaBH4 produces Pt-nanoparticles appearing in the form of irregularly shaped aggregates. Catalytic performance of reduced Pt/P4VP composites in the hydrogenation of unsaturated carbon–carbon bonds in alkene (2-butene-1,4-diol, B2-D) and alkyne (2-butyne-1,4-diol, B3-D) substrates is similar to that of commonly used inorganic oxide supported Pt-catalysts. However, in the presence of Pt/P4VP catalysts the formation of by-products via hydrogenolysis reaction is strongly suppressed owing to a lack of acidic properties of P4VP matrix.

The cumulant method is a model-independent technique based on the expansion of extended X-ray absorption fine structure (EXAFS) amplitudes and phases as a series of cumulants of the interatomic distance distribution.Results show evidence of simple grain boundary formed as amorphous–crystal interface region around BCC Fe nanocrystals. This interface region initially growth along with the growth of the Fe nanocrystals. However, in the latter stage of nanocrystallization, additional contribution of statically disordered interface is formed in nanograin boundaries hindering the grain growth. The disordered interfacial regions can help to explain nanocrystallization phenomenon of Fe85Zr7B6Cu2 alloys.

Palladium was introduced into a conjugated polymer poly(o-methoxyaniline) (POM) by reacting the powdered polymer with aqueous solution of PdCl2 of low acidity (PdCl2: 2.3×10−3mol/dm3, HCl: 0.66×10−3mol/dm3). Various Pd2+ complexes with Cl−, H2O, OH− ligands coexisted in this solution but predominated [PdCl2(H2O)2] ones. Several techniques like X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron and Raman spectroscopy, extended X-ray absorption fine structure have been used to characterize the poly(o-methoxyaniline)–Pd systems. In particular, the state of Pd species in the Pd/POM of various content of palladium (2–8wt.% Pd) and chemical changes in the polymer matrix induced by insertion of palladium were studied. The protonation and redox reactions involved on palladium incorporation resulted in palladium ions and Pd metal in the final samples. Metallic Pd produced due to spontaneous reduction of palladium ions by the polymer formed large crystalline particles 200–1000nm in size. The Pd2+ species in the form of anionic complexes like [PdCl4]2− acted as the counterions at low content of palladium (2–4wt.% Pd). At high palladium content (8wt.% Pd), several atoms like Cl, N and/or O were identified by extended X-ray absorption fine structure (EXAFS) technique in the nearest environment of Pd atoms. The structural groups of POM (like N groups and/or OCH3) as well as H2O, OH− molecules are, therefore, considered as probable species in the coordination sphere of palladium. The catalytic properties were studied for the as-prepared Pd/POM and the samples additionally reduced with aqueous solution of NaH2PO2. They were used in the hydrogenation of CC bonds in maleic acid (MAC) and CO groups in 2-ethylanthraquinone (eAQ) at 60°C and atmospheric pressure of hydrogen using xylene–octanol-2 or water medium. The correlation between Pd/POM activities and the content of Pd metal was found. Activation of the as-prepared Pd/POM with NaH2PO2 improved their catalytic properties. Much higher and much stable activities were then obtained in both MAC and eAQ hydrogenation reactions.

The extended x-ray absorption fine structure (EXAFS) method was applied for studying the local surrounding of palladium ions incorporated in polyaniline samples, which demonstrate different catalytic properties. Our studies showed that mainly Cl ligands were present around Pd ions in polymers. In contrast to X-ray diffraction and X-ray photoelectron studies, for one of samples the EXAFS study revealed a small amount of Pd-Pd bond originating probably from ultrafine Pd clusters, which can explain specific selectivity of catalytic properties of this sample.

The x-ray absorption fine structure (XAFS) method was applied for studying polyaniline and its derivatives poly(o-toluidine) and poly(o-methoxyaniline) doped with platinum at room temperature using two different solutions of PtCl4, namely in H2O and in 0.1 M HCl. The Pt L-3 edge absorption spectra were measured in transmission mode at room temperature using synchrotron radiation. Our studies showed that mainly Cl ligands were present around Pt ions in polymers doped in PtCl4 solution in aqueous HCl, while a mixture of Cl and aqueous ligands appeared around Pt ions in the samples doped in PtCl4 aqueous solution. It was found out that Pt-IV ions were partially reduced to Pt-II ions in polymers studied.

Methods of principal components analysis and linear combinations of XANES (X-ray absorption near edge structure) spectra were applied to determine the composition of Pd species in Pd-doped poly-o-methoxyaniline (POM). A set of reference spectra reproducing the absorption spectrum of Pd/POM polymer was easy to find because of the square-planar structure common for the d8 metal ion Pd(II). Absorption spectra of reference samples such as PdO, Pd(C5H7O2)2, Pd(CH3COO)2, [Pd(NH3)4]Cl2, [Pd(NH3)4](NO3)2, (C3H5PdCl)2, PdCl2(CH3CN)2, PdCl2, (NH4)2[PdCl4], K2PdCl4 and Pd metallic foil were taken into account. Although the XANES fits for the best two sets of reference compounds, (1) Pd(CH3COO)2, (NH4)2[PdCl4], Pd foil and (2) [Pd(NH3)4]Cl2, (NH4)2[PdCl4], Pd foil, were in very good agreement with the experimental XANES spectrum of Pd/POM, only the first model was established as being correct. This was achieved by examining the Fourier transforms of reconstructed EXAFS spectra in comparison to the Fourier transform for the Pd/POM polymer. A quantitative XANES analysis of the composition of Pd/POM led to a final result of 46.0% Pd metal and 54% Pd2+ ions surrounded by four neighbours, including Cl and O ions in an average ratio of 2.6:1.4. The coordination numbers for the Pd–O, Pd–Cl and Pd–Pd near-neighbour shells in the Pd/POM polymer were simply evaluated from the XANES fit analysis.

Reactivity of poly(o-toluidine) in the emeraldine base form (POT) and protonated with HCl (POT/HCl) in PdCl2 aqueous solutions of various HCl concentrations has been studied. Using elemental analysis, FTIR, UV–Vis, XPS and EXAFS spectroscopies as well as XRD and SEM it has been established that POT/HCl is more reactive than POT. The course of reactions is influenced by the type of the PdCl2 solution. Thus, protonation of POT with incorporation of palladium (II) chloro–and/or aquachloro–and/or chlorohydroxycomplexes counterions is the main process occurring in the PdCl2 solutions of higher HCl concentration. A redox reaction resulting in the oxidation of the polymer chain with simultaneous formation of metallic palladium takes place in the PdCl2 solution of lower HCl concentration. POT/HCl shows enhanced reducing properties with respect to POT. Lowering of the protonation level (i.e. some deprotonation) of POT/HCl has been also observed. Coordination of palladium (II) ions by nitrogen atoms of the polymer chain can be also postulated.

The observation of both vertical and lateral ordering of quantum dots in CdTe/ZnTe superlattices with different thickness of ZnTe spacer is reported. The simultaneous presence of both types of ordering in the studied structures is evidenced by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) studies. The TEM results show that when the spacer thickness is smaller than 25 monolayers, the islands are vertically correlated along the axis tilted by 40degrees with respect to the growth direction. On the other hand, the SAXS spectra exhibit four intensity maxima of scattering at q = 0.2 Angstrom(-1) along [100], [(1) over bar 00], [010] and [0 (1) over bar0] crystallographic directions. We interpret them as originating from a locally formed square quantum dot lattice.

Polyaniline doped with palladium (PANI–Pd) demonstrated a particular catalytic activity and selectivity in reaction of the hydrogenation of the triple CC bond. Pd K-edge X-ray absorption near edge structure (XANES) studies were performed for PANI–Pd and several palladium compounds like PdCl2, (NH4)2PdCl4, Pd(NH3)4Cl2, (NH4)2PdCl6, K2PdCl4, [(C3H5)PdCl]2, PdCl2(CH3CN)2 and PdO. The measurements were carried out in transmission mode at the station X1 in HASYLAB. Chemical shifts of Pd K edge for PANI–Pd and other palladium compounds were evaluated. The experimental XANES spectra were compared with the theoretical XANES spectrum calculated for PdCl2 by applying the FEFF8 program. It was found that the Pd K edge XANES spectrum for PANI–Pd was similar to that for ammonium tetrachloropalladate (NH4)2PdCl4. Our results indicated that in the PANI–Pd catalyst the tetrachloropalladate ion [PdCl4]−2 is coordinated to the amine part of the polymer chain and is responsible for specific catalytic properties.

This work is aimed at the comparative analysis (both theoretical and experimental) of the Mn K-edge X-ray absorption fine structure in selected manganese compounds, i.e. MnS, MnPO4·H2O and MnO2 measured in transmission mode by using synchrotron radiation in HASYLAB. The results were analysed by performing the fine structure calculation with feff8 programme. The calculations gave results which conform to the experimental data. We observed an evolution of the pre-edge features and a shift of the main absorption edge toward higher energy with the Mn oxidisation degree.

Anomalous small: angle X-ray scattering (ASAXS) from the molecular beam epitaxially grown multilayers of quantum dots CdTe separated by ZnTe layers on the ZnTe/CdTc(001) Support has been observed. ne samples contained 200 layers of 2.5 ML CdTe separated by 3, 10, 15 and 75 ML ZnTe. An enhancement of x-ray scattering by quantum dots was observed for photon energy near the Zn K absorption edge. SAXS studies have shown that the density of CdTe quantum dots was bigger by factor 40 for the sample 3ML ZnTe and by factor 10 for the sample 15ML ZnTe in comparison to the sample 75ML ZnTe. The scattering curves indicated a broad size distribution of quantum dots in the samples.

Anomalous small angle X-ray scattering (ASAXS) from the molecular beam epitaxially grown multilayers of quantum dots CdTe separated by ZnTe layers on the ZnTe/CdTe/GaAs(001) support has been observed. The first sample denoted 15 ML contained 200 layers of 2.5 ML CdTe/15 ML ZnTe and the second sample denoted 75 ML contained 200 layers of 2.5 ML CdTe/75 ML ZnTe. An enhancement of scattering by quantum dots was observed for photon energy near the Zn K absorption edge. We found that the ASAXS from the 15 ML sample was by one order of magnitude higher than that from the 5 ML sample, which means that the number of quantum dots in the 15 ML sample was one order of magnitude bigger than in the 75 ML sample. The scattering curves indicate a broad size distribution of quantum dots in both samples.

Local structural changes are studied occurring during transformation from amorphous to nanocrystalline phases of Fe85Zr7B6Cu2, Fe73.5Cu1Nb3Si15.5B7 and Fe66Cr8Cu1Nb3Si13B9 alloys. The nanocrystalline state of a formerly amorphous alloy was achieved by heat treatment at temperatures between 420 and 600°C. The high-resolution transmission electron microscopic images have shown the average size of the Fe and Fe(Si) nanograins in nanocrystalline alloys ranging from 5 to 15 nm in alloys at different stages of crystallisation. X-Ray absorption spectra at the K-edge of Fe, Cu and Cr atoms for nanocrystalline alloys measured using synchrotron radiation have shown a different local structure, namely the structure bcc Fe around Fe atoms, fcc Cu around Cu atoms and amorphous around Cr atoms. The growth of fcc Cu clusters before the nucleation of bcc Fe grains in nanocrystalline alloys was observed. It can be considered as a basic mechanism responsible for nanocrystalline grain formation. The FEFF8 program was used for calculations of X-ray absorption spectra up to about 260 eV above the Fe K-edge for bcc Fe metal and Fe3Si compound in terms of self-consistent muffin-tin potential approximation and full multiple scattering approach. The theoretical spectra well explained the experimental result that the amplitude of EXAFS oscillations in Fe3Si was considerably decreased by the presence of Si atoms in comparison to that for Fe metal.

Complexes of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, manganese, and zinc with m-iodobenzoic acid were studied. The FT-IR and FT-Raman spectra of the mentioned compounds in the solid state and water solutions were recorded and analyzed. Principal component analysis (PCA) was performed on the wavenumbers of selected bands (eight bands) occurring in the vibrational spectra. The numbers obtained as a result of this procedure characterize the electronic properties of the molecule of each complex. The antimicrobial activity of the studied compounds against selected bacteria (Escherichia coli and Bacillus subtilis) and yeast (Saccharomyces cerevisiae and Hansenula anomala) was estimated. The relationship between the chemical properties (as characterized by PCA of the IR spectra) and antimicrobial properties of the compounds was examined, and a good correlation between the two factors was found.

BackgroundThe aim of our study was to estimate the efficacy of treatment the fetal hemolytic disease by intravascular transfusions (IVT).MethodIn the group of 71 immunized patients, after 21 weeks' gestation we performed amniocentesis. Results of the optical density at 450 nm in 2nd or 3rd zone in Liley's scale were an indication for cordocentesis, fetal blood sampling and in cases with low values of blood parameters – intravascular transfusion with drugs administration. In some cases we chose elective preterm cesarean delivery. The management depended on the gestational age, fetal maturity, blood parameters, ultrasound examination and FHR patterns.ResultsThe number of 24/71 patients required IVT. We transfused 20–90 ml of blood in 3–10 days intervals. The total amount of IVT was 78: 65/78 into a free loop of umbilical cord and 13/78 into its placental insertion. In 22/24 cases there were born healthy neonates, five of them required exchange transfusion because of hyperbilirubinemia. We observed one intrauterine death 10 h after IVT, probably due to cord hematoma and one death of hydropic neonate 48 h after delivery.ConclusionThe treatment of fetal hemolytic disease by IVT is associated with high perinatal survival rate and low perinatal mortality rate.

Protoplasts of the low yield Mx-3 mutant were transformed with native DNA isolated from the high yield mutant Dy-17. Three transformants were obtained which utilized galactose as a carbon source and produced pullulan at the same level as the high yield mutant Dy-17. The kinetics of pullulan production, cell biomass content, saccharose utilization and changes in pH were compared with batch culture of transformants and parental strains performed in a shaker at 28 degreesC for 96 hours. The analyzed parameters of kinetics for the transformants proved to be similar to the kinetics of the Dy-17 mutant.

The curved-wave multiple-scattering theory and program FEFF were used for calculations of extended X-ray absorption fine structure (EXAFS) at the Fe K edge for the Fe (100) surface. The shape of EXAFS calculated for each atomic layer placed beneath an Fe surface down to the depth of 0.8 nm was different from the EXAFS of bulk Fe, while the EXAFS for deeper layers was identical to that of bulk. The surface EXAFS contribution was obtained as an averaged EXAFS value for atomic layers within a depth of 0.8 nm. Three models of atomic ordering at the surfaces were taken into account: (i) an ideal surface, (ii) rough surface and (iii) statically disordered surface. It was obtained that the first peak of Fourier transform (FT) at radius R=2.3 Å is less by only 6% in the case of surface EXAFS contribution from an ideal Fe surface in comparison to that for bulk Fe, while in the case of a rough surface it is less by 24%, respectively, to bulk Fe. The FT peak at radius R=4.5 Å, which is strongly related to multiple scattering effects is even more reduced, namely by 15 and 30% for an ideal and rough surface, respectively. The Fe K EXAFS spectra were also calculated for an Fe nanocrystal in the form of a cube of size ranging from 3 to 10 nm. The theoretical model calculations were used for interpretation of the Fe K EXAFS experimental data for the nanocrystalline Fe85Zr7B6Cu2 alloy measured using synchrotron radiation.

Nanocrystalline Fe85Zr7B6Cu2 alloys were obtained from the formerly amorphous Fe85Zr7B6Cu2 alloy by a heat treatment at several temperatures ranging from 480 degrees C to 600 degrees C. The ultrafine nanocrystalline structure of bcc-Fe grains with a grain size of 3-15 nm diameter embedded in an amorphous matrix was established using transmission electron microscopy. X-ray absorption spectra at the Fe K-edge for Fe85Zr7B6Cu2 amorphous and nanocrystalline alloys and metallic Fe foil were measured using synchrotron radiation. Fourier analysis of extended X-ray absorption fine structure (EXAFS) for alloys was performed and two models of grain boundaries in nanocrystalline Fe85Zr7B6Cu2 alloys were proposed. The heat treatment of alloys at temperatures of 480 degrees C and 500 degrees C creates simple boundaries between crystalline grains and amorphous matrix, while the heat treatment at higher temperatures from 540 degrees C to 600 degrees C can produce boundaries in the form of Fe-free interfaces with thickness of about 0.3 nm. A model of an Fe-free interface being a barrier for grain growth can explain the nanocrystallization phenomenon of Fe85Zr7B6Cu2 alloys. (C) 1999 Elsevier Science S.A. All rights reserved.

The electronic structure of valence and conduction bands of silicon nitride SiNx layer deposited on a silicon substrate was studied using X-ray photoelectron spectroscopy (XPS) and X-ray bremsstrahlung isochromat spectroscopy (BIS), respectively, and compared with the density of states (DOS) taken from the literature. In the isochromat spectrum measured at photon energy 5415 eV, a strong maximum at 9.7 eV and a weak extended structure in the energy range up to 200 eV above the BIS edge were observed. A theoretical calculation of extended X-ray bremsstrahlung isochromat fine structure (EXBIFS) for silicon nitride has been performed using a multiple scattering method and partial probabilities of X-ray bremsstrahlung transitions calculated for continuum states in a dipole approximation. The results have shown that the X-ray bremsstrahlung isochromat fine structure for silicon nitride appears mainly due to electron transitions to the s states localized near Si ions.