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  • Author or Editor: H. F. Sun x
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Abstract  

The concentration of 8 REEs (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in 17 species of plants and their host soil, which were collected from a rare earth ore area located in the south of China, have been determined by INAA. The chondritic normalized REE patterns for different parts of plants (e.g., leaf stem and root) and their host soils were studied. The results showed that the concentration levels of REE for most plants in the sampling area were elevated. Particularly, the leaves of the fern (Dicranopteris dichotoma) contain extremely high concentration of the total REE (675–3358 g/g) Generally, these REE distribution patterns in every part of plants were very similar and reflected the characteristics of their host soils. However, the chondritic normalized REE patterns in some plants relative to the host soil revealed obvious fractionation, such as the depletion of the heavy REE (for fernCitrus reticulata andBrassia campestris), the heavy REE enrichment (forCamellia sinensis, Camellia oleifera andZiziphus) and the Ce positive anomaly (forGardenia jasminoides).

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Abstract  

Biochemical techniques, including pH variation, outsalting, ultracentrifugation, gel filtration chromatography and electrophoresis, etc., have been employed together with instrumental neutron activation analysis (INAA) to study the rare earth elements (REE) bound proteins in the natural plant fern,Dicranopteris dichitoma. INAA was also used to identify whether the proteins were bound firmly with REE. The results obtained show that two REE bound proteins (RBP-I and RBP-II) have been separated. The molecular weight of RBP-I on Sephadex G-200 gel column is about 8·105 Daltons and that of RBP-II is less than 12,400 Daltons, respectively. However, SDS-PAGE of the two proteins shows that they mainly have two protein subunits with MW 14,100 and 38,700 Daltons. They are probably conjugated proteins, glycoproteins with different glyco-units.

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Abstract  

AP/HTPB based composite propellants with additives such as ammonium oxalate (AO), mixture of ammonium oxalate and strontium carbonate (SC) was investigated by burning rate, TG-DTG and FTIR experiments. The results show that the burning rates of these propellants are decreased significantly. TG-DTG experiments indicate that decomposition temperatures of AP with these additives are increased. Furthermore, the activation energy of the decomposition reaction of AP is also increased in the presence of AO or AO/SC. These results show that AO or AO/SC restrains the decomposition of AP. The burning rates of these propellants are decreased. The burning rate temperature sensitivity of AP/HTPB based propellants is reduced significantly by the addition of AO or AO/SC. But the effect of AO is less than that of AO/SC. AO/SC is better effect to reduce temperature sensitivity and at the same time, to reduce pressure exponent. The reduced heat release at the burning surface of AP/HTPB/AO is responsible for the reduced temperature sensitivity. Synergetic action is probably produced between AO and SC within AP/HTPB based propellants in the pressure range tested. This synergetic effect causes the heat release to reduce and the burning surface temperature to increase. Moreover, it makes the net exothermal reaction of condensed phase become little dependent on T 0. Thus, the burning rate temperature sensitivity is reduced.

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Abstract  

The uranium(VI) accumulation was studied in detail by using the biomass of mangrove endophytic fungus Fusarium sp.#ZZF51 from the South China Sea. The uranium(VI) biosorption process onto the tested fungus powders was optimized at pH 4.0, adsorption time 60 min, and uranium(VI) initial concentration 50 mg L−1 with 61.89% of removal efficiency. According to Fourier transform infrared spectra for the tested fungus before and after loaded with uranium(VI), the results showed that both of hydroxyl and carboxyl groups acted as the important roles in the adsorption process. In addition, the experimental data were analyzed by using parameter and kinetic models, and it was obtained that the Langmuir isotherm model and the pseudo-second-order kinetic model provided better correlation with the experimental data for adsorption of uranium(VI).

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Summary  

Accelerator mass spectrometry (AMS) is an ultra-sensitive method to monitor and trace the environmental exposure levels of 14C-labeled molecules in vivo. Nicotine [3-(1-methyl-2-pyrrolidinyl)-pyridine], a major alkaloid in tobacco products, has proven to be a potential genotoxic compound. Using 14C-labeled nicotine and AMS, we have investigated the inhibitory effect of curcumin, garlic squeeze, grapeseed extract, tea polyphenols, vitamin C and vitamin E, respectively, on nicotine-hemoglobin (Hb) adduction in vivo. The results demonstrated that these dietary constituents induced remarkable decrease of nicotine-Hb adducts. The inhibitory fact may afford an important clue of the chemoprevention of the potential nicotine-induced carcinogenesis.

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Abstract  

Polyaniline/γ-Al2O3 (PANI/γ-Al2O3) composites were synthesized by in-situ polymerization at the presence of HCl as dopant by adding γ-Al2O3 nanoparticles into aniline solution. The composites were characterized by FTIR and XRD. The thermogravimetry (TG) and modulated differential scanning calorimetry (MDSC) were used to study the thermal stability and glass transition temperature (T g) of the composites, respectively. The results of FTIR showed that γ-Al2O3 nanoparticles connected with the PANI chains and affected the absorption characteristics of the composite through the interaction between PANI and nano-sized γ-Al2O3. And the results of XRD indicated that the peaks intensity of the PANI/γ-Al2O3 composite were weaker than that of the pure PANI. From TG and derivative thermogravimetry (DTG) curves, it was found that the pure PANI and the PANI/γ-Al2O3 composites were all one step degradation. And the PANI/γ-Al2O3 composites were more thermal stable than the pure PANI. The MDSC curves showed that the nano-sized γ-Al2O3 heightened the glass transition temperature (T g) of PANI.

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Abstract  

The low-temperature molar heat capacities of CoPc and CoTMPP were measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 223 to 413 K for the first time. No phase transition or thermal anomaly was observed in the experimental temperature range for CoPc. However, a structural change was found to be nonreversible for CoTMPP in the temperature range of 368–403 K, which was further validated by the results of IR and XRD. The molar enthalpy ΔH m and entropy ΔS m of phase transition of the CoTMPP were determined to be 3.301 kJ mol−1 and 8.596 J K−1 mol−1, respectively. The thermodynamic parameters of CoPc and CoTMPP such as entropy and enthalpy relative to reference temperature 298.15 K were derived based on the above molar heat capacity data. Moreover, the thermal stability of these two compounds was further investigated through TG measurements. Three steps of mass loss were observed in the TG curve for CoPc and five steps for CoTMPP.

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Abstract  

A microcalorimetric technique based on the bacterial heat output was applied to evaluate the influence of antibiotics PIP (Piperacillin Sodium) and composite preparation of PIP and SBT (Sulbactam Sodium) on the growth of E. coli DH5α. The power–time curves of the growth metabolism of E. coli DH5α were studied using a TAM Air Isothermal Microcalorimeter at 37C. By analyzing the power–time curves, the parameters such as growth rate constants (k), inhibitory ratio (I), the maximum heat power (P m) and the time of the maximum heat power (t m) were obtained. The results show that different concentrations of antibiotics affect the growth metabolism of E. coli DH5α. The PIP in the concentration range of 0–0.05 g mL–1 has a stimulatory effect on the E. coli DH5α growth, while the PIP of higher concentrations (0.05 –0.25 g mL–1) can inhibit its growth. It seems that the composite preparation composed of PIP and SBT cannot improve the inhibitory effect on E. coli DH5α as compared with the PIP.

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Summary  

Exploratory experiments have been carried out to investigate the effects of gamma-radiation on iodine aerosols under various chemical conditions. The results indicate that iodide ions (I-) in aerosol can be readily oxidized to I2 and HIO, and some iodide ions may be converted to organic iodine when organic additives are present in the KI solution from which the aerosol is generated. The results also suggest that the chemical transformation of irradiated iodine aerosol depends on the chemical environment both carrier gas and iodide solution.

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Abstract  

Polyimide BTDA-ODA sample was prepared by polycondensation or step-growth polymerization method. Its low temperature heat capacities were measured by an adiabatic calorimeter in the temperature range between 80 and 400 K. No thermal anomaly was found in this temperature range. A DSC experiment was conducted in the temperature region from 373 to 673 K. There was not phase change or decomposition phenomena in this temperature range. However two glass transitions were found at 420.16 and 564.38 K. Corresponding heat capacity increments were 0.068 and 0.824 J g–1 K–1, respectively. To study the decomposition characteristics of BTDA-ODA, a TG experiment was carried out and it was found that this polyimide started to decompose at ca 673 K.

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