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991.
A Triton X-100-4.0G-D (4.0G-D refers to a 4.0-generation dendrimer) was brought forward as a new phosphorescence labeling reagent. Two types of specific affinity adsorption (AA) reactions (direct method and sandwich method) were carried out between the labeling product of Triton X-100-4:0G-D-Wheat germ agglutinin (WGA) and alkaline phosphatase (ALP), the product of AA reaction preserved the good characteristics of room temperature phosphorescence (RTP) of 4.0G-D and △Ip of the product was proportional to the content of ALP. According to the fact stated above, a new method for the determination of trace ALP by affinity adsorption solid substrate-room temperature phosphorimetry (AA-SS-RTP) was established on the basis of WGA labeled with the Triton X-100-4.0G-D. The detection limits were 0.20 ag·spot^-1 (corresponding concentration: 5.0×10^-16 g·mL^-1, namely 5.0×10^-18 mol·L^-1) for a direct method and 0.14 ag·spot^-1 (corresponding concentration: 3.5×10^-16 g·mL^-1, namely 3.5×10^-18 mol·L^-1) for a sandwich method, respectively. For their high sensitivity, good repeatability and high accuracy, the direct method and sandwich method have been successfully appfied to determine the content of ALP in human serum, and the results were coincided with the clinical detection results of the enzyme-linked immunosorbent assay method by the Zhangzhou Hospital of Traditional Chinese Medicine. Meanwhile, the mechanism for the determination of trace ALP by AA-SS-RTP was discussed. 相似文献
992.
Electrosorption of hydrogen into palladium-gold alloys 总被引:1,自引:0,他引:1
M. Łukaszewski K. Kuśmierczyk J. Kotowski H. Siwek A. Czerwiński 《Journal of Solid State Electrochemistry》2003,7(2):69-76
Hydrogen electrosorption into Pd-Au alloys has been studied in acidic solutions (1 M H2SO4) using cyclic voltammetry. Pd-Au electrodes with limited volume were prepared by electrochemical co-deposition. It was found
that the maximum H/(Pd+Au) ratios decrease monotonically with increasing gold content and reach zero at ca. 70 at% Au. Similarly
to the case of Pd limited volume electrodes, two peaks in the hydrogen region, corresponding to two types of sorbed hydrogen,
are observed on voltammograms for Pd-rich alloys. The hydrogen capacity, H/(Pd+Au), measured electrochemically, depends on
the sweep rate in the cyclic voltammetry experiments, which suggests that two different mechanisms for hydrogen desorption
from the Pd-Au alloy are possible. After a strong decrease of Pd concentration at the electrode surface, caused by long cyclic
polarization to sufficiently anodic potentials, the amount of absorbed hydrogen is still significant for alloys initially
rich in Pd. The results obtained from CO adsorption experiments suggest that only Pd atoms are active in the hydrogen absorption/desorption
process.
Electronic Publication 相似文献
993.
Bo?AndreassonEmail author Jennie?Forsstr?m Lars?W?gberg 《Cellulose (London, England)》2005,12(3):253-265
It has been shown, in the present investigation, that the two methods used to investigate the pore size distribution of unbleached
chemical pulps, i.e. inverse size exclusion chromatography (ISEC) and nuclear magnetic resonance (NMR), give different average
pore radius for the pores inside the fibre wall. This is due to the way in which these experiments are performed and the sensitivity
of the methods to different types of pores in the cell wall. It was also shown that the two methods gave different results
when changing the pH and the ionic strength of the pulp suspension. The pore radius, as detected with ISEC, decreased with
both increasing ionic strength and decreasing pH, indicating a loose structure of the exterior of the fibrillar network. However,
the pore radius as detected with NMR, was virtually unaffected when increasing the ionic strength, indicating a very rigid
structure of the interior of the fibre wall. Decreasing pH though, lead to a decrease in pore radius indicating that upon
protonation of the carboxylic groups in the fibre wall, the electrostatic repulsion is diminished and the average pore radius
decreases. The NMR technique was also used to study wet strength aid penetration into the fibre wall. It was shown that wet
strength aids with a small molecular weight, penetrated the fibre wall, as detected by a decrease in pore radius. It was also
shown that addition of different wet strength aids increased the tensile index of the sheet and decreased the fibre strength,
measured as zero span-strength of the sheets. 相似文献
994.
Adsorption stripping voltammetry, a very sensitive electroanalytical method, was employed to determine reserpine, a kind of anti-hypertensive drug. In 0.1M phosphate buffer with a pH of 6.0, reserpine was accumulated at a multi-wall carbon nanotubes (MWNT)-modified glassy carbon electrode (GCE) surface under the condition of open-circuit. In the following anodic sweep from 0.20 to 1.00V, reserpine, adsorbed at the MWNT-modified GCE surface, was oxidized and yielded a sensitive oxidation peak at 0.64V. Due to its unique structure and extraordinary properties, MWNT shows a ten times higher accumulation efficiency toward reserpine, compared with a bare GCE. Hence, the amount of reserpine at the MWNT-modified GCE surface increases significantly, and finally the oxidation peak current improves greatly. The experimental conditions, such as supporting electrolyte, pH value, the amount of MWNT-DHP suspension, accumulation time and scan rate, were optimized for the measurement of reserpine, and a sensitive electroanalytical method was proposed for reserpine determination. The oxidation peak current varies linearly with the concentration of reserpine over the range of 2×10–8 to 1×10–5M, and the detection limit is 7.5×10–9M after 4min open-circuit accumulation. The relative standard deviation at 1×10–6M reserpine was about 4.7% (n=7), indicating excellent reproducibility. This new method was successfully demonstrated with reserpine injections and tablets. 相似文献
995.
ZSM-5分子筛吸附分离对二乙苯的研究 总被引:1,自引:0,他引:1
本文用动态法就对二乙苯在ZSM-5分子筛上的吸附进行了研究,考察了温度、脉冲进料量、解吸剂的流速、解吸剂的性质等对分离效果的影响,确定了最佳操作条件:温度为200℃~230℃,常压,以甲苯为解吸剂,解吸剂流量 250~350Kg/m2·h,对二乙苯的单程收率为 60%,纯度>95%。 相似文献
996.
J. G. Dunn A. C. Chamberlain N. G. Fisher J. Avraamides 《Journal of Thermal Analysis and Calorimetry》1997,49(3):1399-1408
The thermal decomposition of SEX in a nitrogen atmosphere was studied by coupled thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), and by pyrolysis-gas chromatography-mass spectrometry (py-GC-MS). The TG curve exhibited two discrete mass losses of 45.8% and 17.8% respectively, at 200 and 257–364°C. The evolved gases identified as a result of the first mass loss were carbonyl sulfide (COS), ethanol (C2H5OH), ethanethiol (C2H5SH), carbon disulfide (CS2), diethyl sulfide ((C2H5)2S), diethyl carbonate ((C2H5O)2CO), diethyl disulfide ((C2H5)2S2), and carbonothioic acid, O, S, diethyl ester ((C2H5S)(C2H5O)CO). The gases identified as a result of the second mass loss were carbonyl sulfide, ethanethiol, and carbon disulfide. Hydrogen sulfide was detected in both mass losses by py-GC-MS, but not detected by FTIR. The solid residue was sodium hydrogen sulfide (NaSH).SEX was adsorbed onto activated carbon, and heated in nitrogen. Two discrete mass losses were still observed, but in the temperature ranges 100–186°C (7.8%) and 186–279°C (11.8%). Carbonyl sulfide and carbon disulfide were now the dominant gases evolved in each of the mass losses, and the other gaseous products were relatively minor. It was demonstrated that water adsorbed on the carbon hydrolysed the xanthate to cause the first mass loss, and any unhydrolysed material decomposed to give the second mass loss.Mr. N. G. Fisher would like to thank the A. J. Parker CRC for Hydrometallurgy for the provision of a PhD scholarship. 相似文献
997.
998.
A simple model of adsorption of large macromolecules on ultra-fine colloidal particles is presented. The basic assumption of the model is that the number of particles attached to a single molecule is a random quantity. Both the reversible and irreversible polymerparticle binding is considered. Also, effects of the non-ideal mixing of polymer solution with suspension and of the polymer/particle size ratio on the shape of the adsorption isotherm are examined. The predictions of the model are confronted with experimental results of the study on the adsorption of very high molecular weight polyacrylamide on fine AgI colloidal particles. 相似文献
999.
In this contribution we propose a simple model of adsorption of a binary (racemic) mixture on a chiraly templated surface. As an example, the adsorption of a liquid mixture of enantiomers on a chiral stationary phase (CSP) is considered. In particular, we study the effect of the lateral interactions in the adsorbed phase on the kinetic and equilibrium isotherms of the enantiomers. Additionally, we investigate the influence of the composition of the surface on the performance of the CSP in the presence of the lateral interactions. To that end, the adsorption of the mixture is modeled by using Monte Carlo simulations as well as by applying an analytical approach involving rate equations coupled with the Mean Field Approximation (MFA). The predictions of the theory are found to be in good agreement with the results of the simulations. 相似文献
1000.
Experimental and Theoretical Study of the Effect of Moisture on Methane Adsorption and Desorption by Activated Carbon at 273.5 K 下载免费PDF全文
Adsorption and desorption of methane by activated carbon (AC) at constant temperature and at various pressures were investigated. The effect of moisture was also studied. A volumetric method was used, up to 40 bar, at a temperature of 273.5 K. Results of a dry AC sample were compared with those obtained from a moist sample and two different ACs with different physical and surface properties were used. As expected, the results showed that the existence of moisture, trapped in the AC pores, could lead to a decrease in the amount of methane adsorbed and a decrease in the amount of methane delivered during desorption. To model the experimental results, a large variety of adsorption isotherms were used. The regressed parameters for the adsorption isotherms were obtained using the experimental data generated in the present study. The accuracy of the results obtained from the different adsorption isotherms was favorably compared. 相似文献