Estimation of the Annual Effective Dose Due to the Ingestion of 210Pb and 210Po in Crops from a Site of Coal Mining and Processing in Southwest China

The exploitation of mineral resources may cause the environmental release of radionuclides and their introduction in the human trophic chain, affecting public health in the short and long term. A case study of the environmental radiation impact from coal mining and germanium processing was carried out in southwest China. The coal mines contain germanium and uranium and have been exploited for more than 40 years. The farmlands around the site of the coal mining and germanium processing have been contaminated by the solid waste and mine water to some extent since then. Samples of crops were collected from contaminated farmlands in the research area. The research area covers a radius of 5 km, in which there are two coal mines. ²¹⁰Pb and ²¹⁰Po were analyzed as the key radionuclides during the monitoring program. The average activity concentrations of ²¹⁰Pb and ²¹⁰Po in the crops were 1.38 and 1.32 Bq/kg in cereals, 4.07 and 2.19 Bq/kg in leafy vegetables and 1.63 and 1.32 Bq/kg in root vegetables. The annual effective doses due to the ingestion of ²¹⁰Pb and ²¹⁰Po in consumed crops were estimated for adult residents living in the research area. The average annual effective dose was 0.336 mSv/a, the minimum was 0.171 mSv/a and the maximum was 0.948 mSv/a. The results show that the crops grown on contaminated farmland contained an enhanced level of radioactivity concentration. The ingestion doses of local residents in the research area were significantly higher than the average level of 0.112 mSv/a in China, and the world average level of 0.042 mSv/a through ²¹⁰Pb and ²¹⁰Po in crop intake, respectively.     

Study on effects of carboxymethyl cellulose lithium (CMC-Li) synthesis and electrospinning on high-rate lithium ion batteries

This study, for the first time, synthesized carboxymethyl cellulose lithium (CMC-Li) by a two-step method and applied it to modified electrode material by electrospinning and as a binder on a lithium ion battery. By electrospinning, nano CMC-Li fiber and CMC-Li/9, 10-anthraquinone (AQ) composite fiber were obtained successfully and coated AQ electrode material. AQ was uniformly distributed in fibers, and then CMC-Li/AQ composite fiber was carbonized to obtain the carbon nanofiber/AQ/Li [CAL] composite as lithium battery anode material. Also for the first time we investigated substituting aqueous CMC-Li with different degrees of substitution (DS) for oily polyvinylidene fluoride (PVDF) as a lithium battery binder to assemble the battery with CAL for electrochemical performance tests. Compared with PVDF binder, cells with CMC-Li for a binder have excellent advantages, such as higher discharge capacity (226.4 mAh g^?1), safer cycle performance, lower cost and being more eco-friendly. Furthermore, the cell with CMC-Li with high DS performed better than the cell with low DS. This method also applies to other electrode materials.     

Pt修饰的Ni/C催化剂电催化氧化乙醇性能

采用两步还原法制备了Pt修饰的Ni/C催化剂(Ni@Pt/C),并应用X射线衍射和透射电子显微镜对催化剂进行了表征.结果表明,载体上催化剂粒子呈两相复合结构,具有较好的分散性,平均粒径为4.4 nm.电化学测试表明,Ni@Pt/C催化氧化乙醇的活性电流高达0.37A/mg,是商业Pt/C催化剂的2.33倍,PtNi/C...     

SBA-15负载硅钨酸催化环己酮Baeyer-Villiger氧化

采用浸渍法制备了H4O40SiW12/SBA-15催化剂,通过红外光谱、X射线衍射、N2吸附-脱附和透射电镜等方法对催化剂进行了表征.结果表明,H4O40SiW12能均匀分散于SBA-15的孔道中,催化剂仍保持载体的介孔结构和硅钨酸的Keggin型结构.将催化剂用于环己酮的Baeyer-Villiger氧化反应中,考察...     

Sol–gel preparation of ZrC–ZrO<Subscript>2</Subscript> composite microspheres using fructose as a carbon source

ZrC–ZrO₂ composite ceramic microspheres were prepared by internal gelation combined with carbothermic reduction using fructose as a chelating agent and carbon source. Fructose in the precursor solution formed complex with zirconium ions, which was conducive to the refining of the microstructure of the sintered composite. ZrC–ZrO₂ composite with ZrC content as high as 60?wt% could be prepared.

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In this paper, fructose was used as a chelating agent and an organic carbon source to prepare ZrCO microspheres by internal gelation and carbothermic reduction. The fructose in the precursor solution could form complex with zirconium ions, which was conducive to the refining of the microstructure of the sintered composite. ZrC–ZrO₂ composite with crystal size of ZrO₂ and ZrC in nanometer range and ZrC content as high as 60?wt% could be successfully prepared.

     

The in vitro biomineralization and cytocompatibility of polydopamine coated carbon nanotubes

In this work, polydopamine coated carbon nanotubes were firstly prepared by a simple and feasible route. Then, for comparison, the in vitro bioactivity and cytocompatibility of the carbon nanotubes and the polydopamine coated carbon nanotubes were assessed by immersion study in simulated body fluids and 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide test using osteoblast cells (MC3T3-E1), respectively. As a result, it has been demonstrated that the introduction of polydopamine coating can greatly enhance the bioactivity and promote cell proliferation of the carbon nanotubes. The improvement of bioactive behavior is attributed to the good combination of catecholamines structure of the polydopamine and the structural advantages of carbon nanotubes as a framework material. It is anticipated that the polydopamine coated carbon nanotubes would find potential applications in bone tissue engineering and other biomedical areas.     

Preparation of albumin—PAA nanocapsules and their controlled release behavior for drugs

New kinds of narrowly distributed protein‐based nanoparticles, bovine serum albumin‐Poly (acrylic acid) (BSA/PAA) nanospheres, and nanocapsules were prepared via in situ polymerization, swelling, and re‐aggregation. The structure and morphology of the nanospheres were characterized by UV‐Vis, FT‐IR, DLS, and TEM. The stability of the BSA/PAA nanospheres and nanocapsules was increased when their skeletons were fixed by cross‐linked agents. The nanospheres carried a positive charge and their size was about 80–110 nm. The protein‐based nanocapsules were stimuli‐responsive with pH value and their hydrodynamic diameter varied from 70 to 230 nm with changes of pH. In vitro release experiments of Rhodamine B and Doxorubicin hydrochloride showed that these biopolymer nanoparticles provided a controlled release of the entrapped drugs for 300 hr. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of the analytical parametric relationship for output spectrum of Volterra systems based on its parametric characteristics

The output frequency response function (OFRF) of Volterra systems can be described as a polynomial function of model parameters. However, the analytical determination of the OFRF is very computationally intensive, especially for higher order OFRF. To circumvent this problem, a numerical method can be adopted, provided that a series of simulation or experimental data for this polynomial function are given. In this study, it is theoretically shown that the analytical parametric relationship of OFRF up to any order can be determined accurately by using a simple Least Square method and every specific component of the output spectrum can also be determined explicitly, based on the OFRF's parametric characteristics. Practical techniques to obtain a unique and accurate solution for the Least Square method are discussed. This study provides a fundamental result for the determination of the analytical parametric relationship for this kind of system polynomial functions by using numerical methods.