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1.
CM Thaker S Rayaprol Krushna Mavani DS Rana MS Sahasrabudhe SI Patil DG Kuberkar 《Pramana》2002,58(5-6):1035-1039
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good
example of these properties is (La1−2x
Pr
x
Ca
x
)MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T
c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using
X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for
understanding the structural, transport and magnetic properties are discussed in detail. 相似文献
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Urgast DS Ellingsen DG Berlinger B Eilertsen E Friisk G Skaug V Thomassen Y Beattie JH Kwun IS Feldmann J 《Analytical and bioanalytical chemistry》2012,404(1):89-99
In recent years, bismuth has been promoted as a "green element" and is used as a substitute for the toxic lead in ammunition and other applications. However, the bioavailability and toxicity of bismuth is still not very well described. Following a hunting accident with bismuth-containing shots, a bioavailability study of bismuth from metal pellets inoculated into rat limb muscles was carried out. Bismuth could be found in urine and blood of the animals. Bio-imaging using laser ablation ICP-MS of thin sections of the tissue around the metal implant was carried out to find out more about the distribution of the metal diffusing into the tissue. Two laser ablation systems with different ablation cell designs were compared regarding their analytical performance. Low concentrations of bismuth showing a non-symmetrical pattern were detected in the tissue surrounding the metal implant. This was partly an artefact from cutting the thin sections but also bio-mobilisation of the metals of the implant could be seen. An accumulation of zinc around the implant was interpreted as a marker of inflammation. Challenges regarding sample preparation for laser ablation and bio-imaging of samples of diverse composition became apparent during the analysis. 相似文献
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Urgast DS Ou O Gordon MJ Raab A Nixon GF Kwun IS Beattie JH Feldmann J 《Analytical and bioanalytical chemistry》2012,402(1):287-297
The kinetics of zinc absorption, metabolism and excretion is extensively studied by nutritionists. Stable isotopes of zinc
can be used to identify body zinc compartments that have different turnover kinetics. Since the compartments might belong
to physiological subsections of different organs, there is a need for microsampling analysis to determine isotope ratios of
the trace element zinc in tissue samples. Here, we study the feasibility to use laser ablation coupled to quadrupole ICP-MS
for the determination of zinc tracers given to rats at different time points with the aim to generate isotope ratio bioimages
of heart tissue. A double tracer (70Zn and 67Zn) experiment with rats was designed to label the exchangeable zinc pool as well as the stable zinc pool. The isotope ratios
determined by laser ablation ICP-MS were evaluated by additional measurements of tissue digests. Accumulated tracers which
made up more than 0.1% of total zinc could be identified in the tissues of the treated rats. It was established that at least
50 measurements from the microsampling were necessary to distinguish between controls and a tracer treated rat resulting in
reduced resolution of the bioimage. With the parameters used, features in the tissue thin sections of at least 250 μm2 in size are necessary to detect the incorporation of a tracer. When different time points have to be measured, higher precisions
are required and therefore a larger area needs to be ablated (1 mm2). Using the bioimages and pool measurements from one physiological feature, it was possible to show that the aorta cell walls
incorporate the zinc tracer at the different time points. 相似文献
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Kinetics and Catalysis - Kinetic study of cholesterol oxidation has been studied using a series of N-cetylpicolinium dichromates (CPDC), a class of phase transfer oxidants, in acetic acid medium... 相似文献
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Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta0.33V0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV2. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase. 相似文献
7.
DS Zhulai SA Bugaychuk GV Klimusheva TA Mirnaya VN Asaula VI Handziuk 《Liquid crystals》2017,44(8):1269-1276
The class of thermotropic ionic liquid crystals (LCs) of the metal alkanoates possesses a number of unique properties, such as intrinsic ionic conductivity, high dissolving ability and ability to form time-stable mesomorphic glasses. These ionic LCs can be used as nanoreactors for the synthesis and stabilisation of different types of nanoparticles (NPs). Thus, some semiconductors, metals and core/shell NPs were chemically synthesised in the thermotropic ionic liquid crystalline phase (smectic A) of the cadmium octanoate (CdC8) and of the cobalt octanoate (CoC8). By applying the scanning electron microscopy, the cadmium and cobalt octanoate composites containing CdS, Au, Ag and core/shell Au/CdS NPs have been studied. NPs’ sizes and dispersion distribution of the NPs’ size in the nanocomposites have been obtained. 相似文献
8.
Th electromagnetic field produced by a magnetic dipole in thepresence of a perfectly conducting cone of arbitrary cross-sectionis determined. The solution is used to find out how a currenton the cone travelling towards the apex is reflected. Some valuesof the reflection coefficient are calculated. In particular,it is shown that there is a sort of resonance with the reflectionincreasing significantly as the cone approaches a plane. 相似文献
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