Summary The ring-oven technique is recommended for the identification and determination of Ca, Sr and Ba in the micro scale. The elements are first converted into their nitrates and Ca is washed out by a mixture of absolute alcohol and ether. Sr is then separated from Ba as soluble diethyldithiocarbamidate in alcohol-ether. The rings obtained are developed by rhodizonate (Sr, Ba) and pyrogallol (Ca). Quantitative determinations are possible by comparison with standard rings. 0.60 g of Ca, 1.31 g of Sr and 8.24 g of Ba can be determined with an error lower than 6%.
Zusammenfassung Zur Trennung und Bestimmung von Ca, Sr und Ba im Mikromaßstab wird die Ringofen-Technik empfohlen. Die drei Elemente werden dabei zunächst in die Nitrate übergeführt und Ca mit Äther-Alkohol ausgewaschen. Sr und Ba werden anschließend mit Diäthyldithiocarbamidat behandelt und Sr mit Äther-Alkohol abgetrennt. Die Identifizierung erfolgt mit Pyrogallol (Ca) bzw. Rhodizonat (Sr, Ba). Durch Vergleich mit Standardproben ist eine quantitative Bestimmung möglich. Hierbei können noch 0,60 g Ca, 1,31 g Sr und 8,24 g Ba mit einem Fehler < 6% erfaßt werden.
Diffusion rates (D) of Au in two amorphous alloys, Fe80B20 and Fe82B18, and of Cu in amorphous Fe82B18 alloy were measured in the temperature range 546–645 K by using the technique of Rutherford backscattering spectrometry (RBS) and Auger electron spectroscopy (AES), respectively. The diffusion of Au was found to be 3 to 6 times faster in Fe80B20 than in Fe82B18, though both the alloys had almost similar crystallization temperatures. The observed differences in the diffusion rates corroborate the fact that Fe80B20 has a more open structure than Fe82B18 as revealed from the reported values of the metal packing fractions of these two alloys. Also, the diffusivities of smaller sized Cu atoms (radius: 0.128 nm) were found to be higher by more than an order of magnitude than those of larger sized Au atoms (radius: 0.146 nm), suggesting a dependence ofD on the size of the diffusing species. 相似文献
A rapid, simple, sensitive and specific liquid chromatography–tandem mass spectrometry method was developed and validated for simultaneous quantification of itopride hydrochloride and domperidone in human plasma. Both drugs were extracted by liquid–liquid extraction with ethyl acetate and saturated borax solution. The chromatographic separation was performed on a reversed-phase C18 column with a mobile phase of water–methanol (2:98, v/v) containing 0.5% formic acid. The protonated analyte was quantitated in positive ionization by multiple reaction monitoring with a mass spectrometer. The assay exhibited linearity over the concentration range of 3.33–500 ng mL−1 for itopride hydrochloride and 3.33–100 ng mL−1 for domperidone in human plasma. The precursor to product ion transitions of m/z 359.1–72.3 and 426.0–147.2 were used to measure itopride hydrochloride and domperidone respectively. The method was found suitable for the analysis of plasma samples collected during phase 1 pharmacokinetics study of itopride HCl 50 mg and domperidone 20 mg in 12 healthy volunteers after single oral doses of the combination drug.
A multiple component structure consisting of two Euler-Bernoulli beams connected to a rigid mass is used to model the heave dynamics of a wing micro air vehicle. In the time domain, the attainment of a C0-semigroup in the context of sesquilinear forms is demonstrated. In addition, the closed loop system is demonstrated to generate an exponentially stable C0-semigroup. In the frequency domain, the infinite dimensional transfer function is determined and used to examine several properties of the system. Finally, an optimal control is used to morph the wings to a desired shape, and simulation results are demonstrated. 相似文献
We report the synthesis and characterization of a novel NIR fluorescent deoxyglucose analogue, CyNE 2-DG. Experiments in different cell lines showed a preferential uptake of CyNE 2-DG in cancer cells and its effective competition with unlabeled d-glucose. Cell imaging experiments demonstrated the superior cell-permeability of CyNE 2-DG over the NIR standard IRDye 800CW 2-DG, and validated its application for cancer cell imaging in the NIR region. 相似文献
A great deal of effort has been made over the last decades to develop a better polarized electron source for high energy physics. Several laboratories operate DC guns with a gallium arsenide photocathode, which yield a highly polarized electron beam. However, the beam's emittance might well be improved by using a superconducting radio frequency (SRF) electron gun, which delivers beams of a higher brightness than that from DC guns because the field gradient at the cathode is higher. SRF guns with metal and CsTe cathodes have been tested successfully. To produce polarized electrons, a Gallium-Arsenide photo-cathode must be used: an experiment to do so in a superconducting RF gun is under way at BNL. Since a bulk gallium arsenide (GaAs) photocathode is normal conducting, a problem arises from the heat load stemming from the cathode. We present our measurements of the electrical resistance of GaAs at cryogenic temperatures, a prediction of the heat load and verification by measuring the quality factor of the gun with and without the cathode at 2 K. We simulate heat generation and flow from the GaAs cathode using the ANSYS program. By following the findings with the heat load model, we designed and fabricated a new cathode holder (plug) to decrease the heat load from GaAs. 相似文献
A new reagent has been synthesized by coupling anthracene moiety to L-leucine. The reagent is characterized by different analytical techniques. It is capable for easy identification of various amino acids on thin-layer chromatography plates by developing distinguishable colors (detection limit between 0.1-0.5 μg at cold condition and 0.1-0.4 μg after heating). This reagent also binds with different amino acids very strongly in solution (methanol). Estimation of equilibrium binding constants of this new reagent with different amino acids has also been carried out. The values of the binding constants are lowest for L-Tyrosine (6.86 × 103 dm3 mol(-1)) and highest for L-Arginine monohydrochloride (8.86 × 10? dm3 mol(-1)) at 25°C. A theoretical study (Hartree-Fock) has been performed to investigate the interaction of the reagent with a representative amino acid, glycine. 相似文献
A series of biologically important isoindolone embedded heterocycles such as tetracyclic 2,4-diamino-5-aryl-10-oxo-10H-1,10a-diazaindeno[2,1-a]indene-3-carbonitriles and tricyclic 1-aryl-3,5-dioxo-1H-imidazo-[3,4-b]isoindoles have been synthesized from an easily derived common intermediate, 3-(2′-hydroxyaroyl)-2,3-dihydroisoindol-1-ones. The significant advantages of the present methodologies are the use of simple and easily available starting materials and reagents, operational simplicity, and good yields of the products with high atom-economy. 相似文献
Kinetics of aqua ligand substitution from [(H2O)(tap)2RuORu(tap)2(H2O)]2+ {tap = 2-(m-tolylazo)pyridine}, by three vicinal dioximes, namely dimethylglyoxime (L1H), 1,2-cyclohexanedione dioxime (L2H) and α-furil dioxime (L3H), have been studied spectrophotometrically in the 35–50 °C temperature range. The reaction was monitored at 560 nm where the absorbance between the reactant and product is at a maximum. At pH 7.4, the reaction has been found to proceed via two distinct consecutive steps, i.e., it shows a non-linear dependence on the concentration of ligands: the first process is [ligand] dependent but the second step is [ligand] independent. The rate constants for the processes are: k1 ~ 10?3 s?1 and k2 ~ 10?4 s?1. The activation parameters, calculated from Eyring plots, suggest an associative mechanism for the interaction process. From the temperature dependence of the outer sphere association equilibrium constants, the thermodynamic parameters were also calculated, which give negative ΔG° values at all temperatures studied, supporting the spontaneous formation of an outer sphere association complex. The product of the reaction has been characterized with the help of IR and ESI-mass spectroscopic analysis. 相似文献