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51.
52.
Karen Inge TaastiAxel Nørlund Christensen Poul NorbyJonathan C. Hanson Bente LebechHans J. Jakobsen Jørgen Skibsted 《Journal of solid state chemistry》2002,164(1):42-50
The zinc fluoro phosphate Zn2F(PO4) has been produced by hydrothermal synthesis employing hydrofluoric acid as a mineralizer in a H2O or D2O medium. A single-crystal X-ray synchrotron diffraction analysis of Zn2F(PO4) shows that the zinc fluoro phosphate is monoclinic, a=9.690(1), b=12.793(1), and c=11.972(1) Å, β=108.265(1)°, space group P21/c, No. 14, Z=16. Reflections hkl with k=2n+1 are weak but significant and the structure shows pseudosymmetry. Zn2F(PO4) has the wagnerite-type M2F(XO4) structure with four Zn atoms each coordinated to four O atoms and one F atom while four other Zn atoms are coordinated to four O atoms and two F atoms. A difference Fourier map, calculated from the single-crystal X-ray data, shows additional electron density close to the four fluorine atoms, indicating a possible partial substitution of F− by OH− ions. This is unambiguously confirmed by 31P-{1H} cross-polarization magic-angle spinning (MAS) and by 1H/2H MAS NMR spectroscopy. The narrow line width observed for the 1H resonance and the unique set of 2H quadrupole coupling parameters (obtained for the Zn2F(PO4) sample using D2O as medium) show that 1H/2H is present as OH(D) groups rather than as water of crystallization in the structure. Quantitative 1H MAS NMR analysis shows that the composition of the sample is Zn2(OH)0.14(3)F0.86(3)(PO4). The high-speed 19F MAS NMR spectrum exhibits two resolved resonances with equal intensity, which are ascribed to an overlap of resonances from the four distinct fluorine sites in Zn2(OH)0.14(3)F0.86(3)(PO4). 相似文献
53.
The unfolding of etiolated barley leaves was induced by two short pulses of light separated by a dark interval. For certain wavelengths of light the effect of the “second light pulse was enhanced when the pulse was given after a 300–2000 s dark interval as compared with its effect when the two light pulses were given simultaneously. We investigated the spectral dependence of the effect of the first, inducing light flash and of the effect of the second Light flash given after a 500 s dark interval. The spectral actinity for the effect of the first flash showed phytochrome involvement. The spectral actinity for the effect of the second light flash, however, was shifted towards shorter wavelengths and the inductive action of red and far red light was attenuated. 相似文献
54.
The application of enriched stable isotopes of minerals and trace elements as tracers in biological systems is a rapidly growing
research field that benefits from the many new developments in inorganic mass spectrometric instrumentation, primarily within
inductively coupled plasma mass spectrometry (ICP-MS) instrumentation, such as reaction/collision cell ICP-MS and multicollector
ICP-MS with improved isotope ratio measurement and interference removal capabilities. Adaptation and refinement of radioisotope
tracer experiment methodologies for enriched stable isotope experiments, and the development of new methodologies coupled
with more advanced compartmental and mathematical models for the distribution of elements in living organisms has enabled
a broader use of enriched stable isotope experiments in the biological sciences. This review discusses the current and future
uses of enriched stable isotope experiments in biological systems. 相似文献
55.
56.
I. V. Bodnar V. F. Gremenok W. Schmitz K. Bente Th. Doering 《Crystal Research and Technology》2004,39(4):301-307
The (CuInSe2)x(2ZnSe)1‐x and (CuInTe2)x(2ZnTe)1‐x solid solution crystals prepared by Bridgman method and chemical vapor transport have been studied. The nature of the crystalline phases, the local structure homogeneity and composition of these materials have been investigated by X‐ray diffraction (XRD) and Electron Probe Microanalysis (EPMA) methods. The analysis revealed the presence of chalcopyrite‐sphalerite phase transition between 0.6 ≤ X ≤ 0.7. Lattice constants, value of σ position parameter and bond length between atoms were also calculated. It was found that the lattice parameters exhibit a linear dependence versus composition. The transmission spectra of solid solution crystals in the region of the main absorption edge were studied. It was established that the optical band gap of these materials changes non‐linearly with the X composition. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
57.
Nguyen TT Østergaard J Stürup S Gammelgaard B 《Analytical and bioanalytical chemistry》2012,402(6):2131-2139
A capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) method was developed for separation of
the free oxaliplatin drug substance from liposome-entrapped oxaliplatin. Simultaneous determination of phosphorous and platinum
opened the possibility to simultaneously monitor the liposomes (phospholipids) and platinum-based drug. In order to suppress
the interferences, argon gas was used as a collision gas in ICP-MS. A detection limit of 29 ng/mL of platinum and a precision
of 2.9% (for 10 μg/mL of oxaliplatin standard) were obtained. Measurement of the total concentration of free and encapsulated
oxaliplatin by CE-ICP-MS was compared with total determination by ICP-MS after microwave digestion and showed a good agreement.
A liposomal formulation of oxaliplatin based on PEGylated liposomes was used as a model drug formulation. Studies of accelerated
drug release induced by sonication and phospholipase A2 catalyzed hydrolysis were performed. It was demonstrated that the CE-ICP-MS was an efficient in vitro characterization method
in the development and quality assurance purposes of lipsome-based formulation of metallodrugs. 相似文献
58.
D. M. Unuchak K. Bente V. A. Ivanov V. F. Gremenok 《Crystal Research and Technology》2010,45(11):1113-1116
The PbxSn1‐xS (x = 0 – 0.25) thin films were prepared on glass substrates by hot wall vacuum deposition. The films were polycrystalline monophase in nature and had orthorhombic crystal structure. The thickness of the films was about 2‐3 μm. The temperature dependences of the conductivity were measured in the temperature range from 150 to 420 K. The films revealed p‐type of conductivity. The Seebeck coefficient and conductivity values of the films was in the range of α = 6 – 360 μV/K and σ = 4.8×10‐5 – 1.5×10‐2 Ω‐1·cm‐1, respectively, at room temperature depending on concentration of the lead in the films. The lead atoms created the substitution defects PbSn in the crystal lattice of the PbxSn1‐xS. These defects formed the donor energy levels in the band gap. The activation energy of the films increased in the range ΔEa = 0.121 – 0.283 eV with increasing of the lead concentration. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
59.
B. V. Korzun A. A. Fadzeyeva K. Bente W. Schmitz S. Schorr 《Crystal Research and Technology》2006,41(2):168-173
Investigations of the thermal expansion of (CuAlTe2)1–x(CuAlSe2)x solid solutions in the temperature range from 100 to 800 K have been carried out for the first time. It has been demonstrated that the thermal expansion coefficient αL grows considerably in the temperature range from 100 to 300 K, whereas the temperature dependence above 300 K is rather weak. The isotherms of composition dependence of the thermal expansion coefficient αL for 100, 293, 500 and 800 K were constructed, and it was found that linear relations could express them. The Debye temperatures θD , the average mean‐square dynamic displacements , the average root‐mean‐square amplitudes of thermal vibration RMS , the anion position parameter u using S. C. Abrahams & J. L. Bernstein (uAB ) and J. E. Jaffe & A. Zunger (uJZ ) models were calculated. The composition dependence of microhardness H using the phenomenological theory was also calculated, and it was discovered that this dependence has a non‐linear character with a maximum of 383 kg/mm2 at x=0.67. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献