Biomedical subjects

Zhimei Sun

Publications and source records attributed to Zhimei Sun.

6 recordsLinked to original sources

PubMed2006

Cloud point extraction and graphite furnace atomic absorption spectrometry determination of manganese(II) and iron(III) in water samples.

Cloud point extraction (CPE) was applied as a preconcentration step prior to graphite furnace atomic absorption spectrometry (GFAAS) determination of manganese(II) and iron(III) in water samples. After complexation with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), the analytes could be quantitatively extracted to the phase rich in the surfactant p-octylpolyethyleneglycolphenylether (Triton X-100) and be concentrated, then determined by GFAAS. The parameters affecting the extraction efficiency, such as solution pH, concentration of PMBP and Triton X-100, equilibration temperature and time, were investigated in detail. Under the optimum conditions, preconcentration of 10 ml of sample solution permitted the detection of 0.02 ng ml(-1) of Mn(II) and 0.08 ng ml(-1) of Fe(III) with enrichment factors of 31 and 25 for Mn(II) and Fe(III), respectively. The proposed method was applied to determination of trace manganese(II) and iron(III) in water samples with satisfactory results.

Iron↗

PubMed2006

Determination of trace nickel in water samples by cloud point extraction preconcentration coupled with graphite furnace atomic absorption spectrometry.

A new method based on the cloud point extraction (CPE) preconcentration and graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the determination of trace nickel in water samples. When the micelle solution temperature is higher than the cloud point of surfactant p-octylpolyethyleneglycolphenyether (Triton X-100), the complex of Ni2+ with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) could enter surfactant-rich phase and be concentrated, then determined by GFAAS. The main factors affecting the cloud point extraction were investigated in detail. An enrichment factor of 27 was obtained for the preconcentration of Ni2+ with 10 mL solution. Under the optimal conditions, the detection limit of Ni2+ is 0.12 ng mL(-1) with R.S.D. of 4.3% (n = 10, c = 100 ng mL(-1)). The proposed method was applied to determination of trace nickel in water samples with satisfactory results.

Nickel↗

PubMed2006

Structure of phase change materials for data storage.

Phase change materials based on chalcogenide alloys play an important role in optical and electrical memory devices. Both applications rely on the reversible phase transition of these alloys between amorphous and metastable cubic states. However, their atomic arrangements are not yet clear, which results in the unknown phase change mechanism of the utilization. Here using ab initio calculations we have determined the atomic arrangements. The results show that the metastable structure consists of special repeated units possessing rocksalt symmetry, whereas the so-called vacancy positions are highly ordered and layered and just result from the cubic symmetry. Finally, the fast and reversible phase change comes from the intrinsic similarity in the structures of the amorphous and metastable states.

Journal Article↗

PubMed2006

Cloud point extraction preconcentration of manganese(II) from natural water samples using 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and triton X-100 and determination by flame atomic absorption spectrometry.

The possibility was investigated by using 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) as the chelating reagent for separation and preconcentration of manganese(II) by cloud point extraction (CPE) and subsequent determination by flame atomic absorption spectrometry (FAAS). The effects of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and time on cloud point extraction were studied. Under the optimum conditions, preconcentration of 10 ml of sample solution permitted the detection of 1.45 ng mL(-1) of manganese with an enrichment factor of 20. The proposed method was applied to the determination of trace manganese in water samples with satisfactory results.

Chemistry Techniques, Analytical↗

PubMed2006

[Inhibitory effect of pyrazole compound DL-1 on soil nitrification: a preliminary study].

The study with soil incubation test under constant temperature and humidity showed that compared with DCD, DL-1 could significantly inhibit the oxidation of soil ammonium. In the first 3 weeks of incubation, DL-1 had an inhibitory effect of >70% on soil nitrification, with the best effect during 14-28 d of incubation. On the 14, 21, and 28 d of incubation, DL-1 with its dosage being 1.0 % of (NH4)2SO4-N decreased the soil NO3- -N content by 26.23%, 33.27% and 23.31%, respectively, compared with the same dosage of DCD, and by 71.12%, 69.10% and 55.14%, respectively, compared with no inhibitors applied. When the dosage of DL-1 accounted for 2.0% of applied N, soil nitrification was strongly inhibited, and soil NO3- -N content remained at a lower level till to the end (90 d) of incubation.

Ammonia↗

PubMed2004

[Effects of different application rates of humic acid compound fertilizer on pepper and its mechanism of anti-senility and incremental yield].

The effects of different application rates of humic acid compound fertilizer (HA) on the yield and physiological characteristics of pepper (Capsicum frutescens L.) were studied in this paper. The results showed that different application rates of (HA) could affect the physiological activities and yield of pepper. The nitrate reductase activity (NRA) and peroxidase (POD) activity were improved with increasing application rate, but the change rate of NRA was reduced gradually. POD activity in inorganic compound fertilizer treatment was improved significantly when the application rate of fertilizer was higher than 0.3 g.kg-1, but that in HA treatment changed smoothly. Superoxide dismutase (SOD) activity was improved significantly when the application rate of fertilizer was lower than 0.2 g.kg-1, and decreased gradually when the application rate was higher than 0.2 g.kg-1. The change of transpiration rate was consistent with that of SOD activity. The relationship between the application rate of fertilizer and the yield of pepper could be described with quadratic curve regression model. According to the equation, the highest application rate of HA should be 0.27 g.kg-1, and the highest yield of pepper could reach 165.22 g per pot.

Capsicum↗