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41.
42.
Inorganic electrides are a novel kind of ionic compounds in which the anions are electrons confined in a complex array of cavities or channels and the cations are nanoscale arrays of alkali metal ions that provide charge balance. In electrides the donated electron behaves like a low-density correlated electron gas, whereby the dimensionality of the electron gas and its electronic and magnetic properties are determined by the topology of the cavities in the host matrix. Unlike traditional electrides, in which alkali cations are encapsulated within an organic cage, inorganic electrides are thermally stable. The current inorganic electrides based on alkali metal loaded zeolites can be designed as useful reduced-dimensionality materials. Inorganic electrides are powerful reducing agents, and they are able to reduce small aromatic molecules to the radical anions within the channels of the zeolite. 相似文献
43.
A simple and accurate RP-HPLC method using photodiode array detection (PAD) was developed for the simultaneous determination of four flavonoids, namely quercetin (QU),luteolin(LU),apigenin(AP) and isorhamnetin (IS) in pigeonpea leaves.Extract samples were separated on HIQ SIL C18V column using methanol-acetonitrile-water(31:10:59, v/v/v) as mobile phase.The flavonoids were detected at 254.5 nm for QU and IS, and at 345 nm for LU and AP.Contents were determined with satisfactory repeatability (R. S. D. < 2.2%) and recovery (97.27 – 99.98%). The developed method was found to be simple and efficient. 相似文献
44.
45.
钪—镧—对氟偶氮氯膦体系共显色效应的研究及应用 总被引:3,自引:0,他引:3
本文研究了钪-镧-对氟偶氮氯膦体系共显色效应的光度特性及测定钪的最佳条件,建立了光度法测定痕量钪的新方法。该法的表观摩尔吸光系数为8.57×10^4L·mol^-1·cm^-1,Sc(Ⅲ)浓度在0.0-5.0μg/25ml范围符合比尔定律。将本法用于镁基,铁基合成试样中痕量钪的测定,结果满意。 相似文献
46.
地质样品中金,银,铊等元素的连续原子吸收光谱法测定 总被引:4,自引:0,他引:4
本文提出了一个一次称样连续测定金、银、铊的简便、快速的新方法。该法是以泡塑吸附金、铊,使银等定量地保留在溶液中。泡塑上的铊用EDTA解脱后,再用硫脲溶液继续解脱金,然后,采用原子吸收光谱法连续测定金、银、铊。方法用于黄铁矿、方铅等单矿矿物及岩石、土壤样品中xng/g~xxxμg/g金、银、铊的测定,获得满意结果。 相似文献
47.
J C Zhu C H Li Y Liu Z H Zhang A X Hou S S Qu 《Journal of Thermal Analysis and Calorimetry》2006,83(1):181-186
After the occurrence of 'Minamata disease' in 1950,
mercury aroused much more attention, and lots of studies concerned have been
made. The purpose of the present paper is to study the effect of mercuric
chloride on the mitochondria suspension isolated from the liver tissue of Cyprinus carpio from the direct viewpoint of energy
by using the microcalorimetric method. The metabolic thermogenic curves of
the mitochondria suspension at 25°C were obtained, and the mitochondria
metabolic thermokinetic equations were established, from which we obtained
the thermodynamic and thermokinetic parameters: thermogenic rate constant
(k), heat output (Q),
average heat power (Pav),
etc. Experimental results indicated that low concentration of mercuric chloride
(5 nmol Hg2+/(mg protein)) stimulates the thermogenesis
of mitochondria, suggesting a strong effect of uncoupling action, while high
concentration of mercuric chloride (20 nmol Hg2+/(mg
protein)) inhibits the metabolism of mitochondria completely, suggesting a
fatal effect on the phosphorylation system. The effect of Hg2+
on mitochondria is concentration-depended, from which the probable reaction
mechanism of Hg2+ to the mitochondria was proposed.
So the microcalorimetric method can be used in the toxicology research. 相似文献
48.
Ultra-long single-crystalline trigonal selenium submicrotubes were synthesized using a facile one-step solution-phase approach with the assistance of nonionic surfactant Polyoxyethylene(20)sorbitan monolaurate (Tween-20), which turned out to be significant for the formation of ultra-long Se submicrotubes. XRD, Raman, SEM, and TEM were adopted to characterize the morphology, structure and phase composition of the as-prepared Se products. It was found that the length of the obtained Se submicrotubes was over 100 microm. By variation of the experimental parameters, the t-Se spheres, nanowires, and broken microtubes can be prepared. The possible growth mechanism of the ultra-long selenium submicrotubes was explained. In addition, we have also demonstrated that the synthesized ultra-long t-Se submicrotubes using the Tween-20-assisted approach can electrochemically charge and discharge with the high capacity of 265 mAh/g (corresponding to 0.97 wt % hydrogen in SWNTs) under normal atmosphere at room temperature. Cyclic voltammetry was adopted to investigate the adsorption-oxidation behavior of ultra-long selenium submicrotubes. It was observed that the morphology of the synthesized selenium products had a remarkable influence on their capacity of electrochemical hydrogen storage. These differences in hydrogen storage capacity are likely due to the size and density of tubes as well as the microcosmic morphology of different Se samples. The as-obtained ultra-long Se submicrotubes are expected to find wide applications in hydrogen storage, high-energy batteries, and optoelectronic, biologic, and catalytic fields as well as in the studies of structure-property relationships. This simple Tween-assisted approach might be extended to the preparations of one-dimensional nanostructures of tellurium and other anisotropic materials. 相似文献
49.
50.
Dielectric properties and frequency response of self-assembled monolayers of alkanethiols 总被引:1,自引:0,他引:1
Wang B Luo J Wang X Wang H Hou JG 《Langmuir : the ACS journal of surfaces and colloids》2004,20(12):5007-5012
This paper presents dielectric properties of alkanethiol self-assembled monolayers (SAMs) under an ac electric field. Using a Hg-SAM/SAM-Hg junction, we measured the ac impedance of alkanethiol SAMs using a sinusoidal perturbation of 30 mV (peak-to-peak) with frequency ranging from 1 Hz to 1 MHz at zero bias. Semicircles at higher frequencies and at middle frequencies along with Warburg lines at lower frequencies were observed in complex plane impedance plots, that is, Nyquist plots. The frequency response of SAMs was analyzed by modeling the junction using an equivalent circuit and fitting the Nyquist plots. The semicircles at higher frequencies are attributed to the effect of the SAM/SAM interfaces, and the ones at middle frequencies are attributed to the effect of alkanethiol SAMs. The comparison in the plots of the imaginary part of the impedance Z against frequency for the bare Hg electrodes (in pure ethanal) and the SAM-covered Hg electrodes (in alkanethiol solution) supports the analysis. The Warburg lines are attributed to a certain ionic impurity. The dielectric loss spectra are further analyzed. Chain-length-dependent peaks, which correspond to different relaxation mechanisms, at higher frequencies and middle frequencies were observed in the spectra of the dissipation factor (tan delta vs frequency). The peaks move to small frequency with the increase of chain length of alkanethiols. Using a correlation of peak position with the chain length, we then derived active energies of 39-99 meV for alkanethiol SAMs of C7-C18 under an ac electric field. 相似文献