The behaviour of p,p-DDE in upland and flooded soil conditions was studied by using14C-p,p-DDE in Hangzhou, China. The dissipation speed of14C-DDE from upland soil is faster than that from flooded soil, especially in the second phase. In flooded soil, 0–8 week T1/2=3.42 (methanol extractable); 8–43 week, T1/2=10.10; in uplan soil, 0–8 week, T1/2=3.22; 8–43 week, T1/2=7.22. There is not too much difference in the distribution patten between upland and flooded soil. Most of the14C-residue is within 2 cm layer of soil column. DDE is very stable in both upland and flooded soil conditions. Experiments were carried out under natural conditions in a net house. LSC (Pachard 1900TR) was used for14C-counting. TLC technique was engaged for the analyzing of its degradation products.
Authors:Shi Xu, Sheng Li, Yun Wei, Li Zhang and Fei Xu
Titanium dioxide (TiO2), polythiophene and polythiophene/TiO2 were prepared by sol–gel and solid-state reaction methods. Water-free iron(III) chloride (FeCl3) was used as an oxidant. The phase composition, morphology and the spectral properties of the products were characterized by XRD, TEM, UV–Vis and FT-IR techniques. The photocatalytic activity of the products was evaluated by the degradation of methyl orange under sunlight irradiation. TEM results showed that the polythiophene/TiO2 composite particles were well dispersed, rod-like shaped with 20 × 80 nm dimensions. UV–Vis analysis indicated that the absorption edge of polythiophene/TiO2 was 605 nm. Compared with the unmodified TiO2 and bare polythiophene, polythiophene/TiO2 exhibited largely enhanced activity for the photocatalytic degradation of methyl orange under sunlight irradiation. A degradation efficiency of methyl orange of 85.6% could be obtained within 120 min. The sensitization mechanism of polythiophene for the TiO2 photocatalyst is discussed briefly.
This work contributed to the adsorption of radiocobalt on goethite as a function of contact time, pH, ionic strength and foreign
ions in the absence and presence of fulvic acid (FA) under ambient conditions. The results indicated that adsorption of Co(II)
was dependent on ionic strength and foreign ions at low pH values (pH < 7.8), and independent of ionic strength and foreign
ions at high pH values (pH > 7.8). Outer-sphere surface complexation and/or ion exchange were the main mechanisms of Co(II)
adsorption on goethite at low pH values, whereas inner-sphere surface complexation was the main adsorption mechanism at high
pH values. The presence of FA enhanced Co(II) adsorption at low pH values, but reduced Co(II) adsorption at high pH values.
The thermodynamic data (ΔH0, ΔS0, ΔG0) were calculated from the temperature dependent adsorption isotherms, and the results suggested that adsorption process of
Co(II) on goethite was spontaneous and endothermic. The results are crucial to understand the physicochemical behavior of
Co(II) in the nature environment.
Authors:Linglin Xu, Peiming Wang and Guofang Zhang
The influence of calcium sulfate with different reactivities (anhydrite, α-hemihydrate, and gypsum) on the Portland cement–calcium aluminate cement (PC/CAC) mixtures was presented in the paper. The hydration process and main hydration products (ettringite) of the binders with different content of calcium sulfate was investigated by isothermal conduction calorimetry, setting times, compressive strength, X-ray diffraction (XRD) analysis, and environmental scanning electronic microscope (ESEM) analysis. It is found that the pure PC/CAC mixture without any calcium sulfate addition exhibits very slow hydration kinetics during the first 2 days. By adding calcium sulfate, the setting of the PC/CAC mixture is delayed, but the hydration can be accelerated. The results also show that the reactivity and the amount of the calcium sulfate determine the balance between the hydration products of ettringite and monosulphoaluminate, and also the early hydration kinetics not only in the formation content but in the location of ettringite. In general, when a high content of reactive α-hemihydrate is added, much secondary gypsum forms in voids between cement granules which exert adverse effects on the properties of PC/CAC mixtures. Additionally, ettringite can be formed stably and good binders having good physical properties can be obtained when low reactive anhydrite is added.
This paper provides an overview of the progression of technology structure based on patent co-citation networks. Methods of patent bibliometrics, social network analysis and information visualization are employed to analyze patents of Fortune500 companies indexed in Derwent Innovations Index, the largest patent database in the world. Based on the co-citation networks, several main technology groups are identified, including Chemicals, Petroleum Refining, Motor Vehicles, Pharmaceuticals, Electronics, etc. Relationships among the leading companies and technology groups are also revealed.
Authors:Fan Lan, Xiang Wang, Xianglan Xu, Rongbin Zhang and Ning Zhang
SnO2 catalysts were prepared with the precipitation method by varying the pH and SnCl4 concentration. For comparison, another two SnO2 samples were also synthesized with sol–gel and combustion methods. All of the catalysts were characterized by N2-BET, XRD and H2-TPR. It was found that the CO oxidation activity of the precipitation samples increases with an increase in pH, while the CH4 oxidation activity seems unchanged. The change of the SnCl4 concentration has little influence on the activity for both CO and CH4 oxidation. The sol–gel sample has relatively higher CO but similar CH4 oxidation activity, due to its higher surface area and finer particle sizes. On the contrary, the combustion sample displays the lowest activity for both reactions, due to its extra low surface area and inert oxygen species.
To investigate the nutritional characteristics of purple wheat, 41 kinds of nutrients were measured in seven purple wheat lines using one white wheat variety as control sample. Correlation analysis of nutrient contents was performed. Results show that the amounts of 40 kinds of nutrients in the purple wheat lines are higher than those of the control. For example, the amounts of sodium (Na) and manganese (Mn) in purple wheat are higher than the standards by 311.77–2017.65% and 548.15–733.33%, respectively; the contents of β + γ-vitamin E is higher than the standards by 300%; and zinc (Zn), iron (Fe), magnesium (Mg), and potassium (K) are all higher than the control by 100%. Therefore, the purple wheat has obvious advantages in terms of the nutrient contents. Correlation analysis studies show that protein has significant positive correlations with Glu, Mo, Pro, Fe, Tyr and Ile. Anthocyanin has significant positive correlations with Mo and Glu, and significant negative correlations with free Trp and Ca. Carotenoid has significant positive correlations with His, Lys, Val, Leu, Arg, Gly and I, and significant negative correlations with Ca. This paper is a first report on comprehensive nutrients of several purple wheat lines. Our results suggest that purple wheat is rich in nutrients and there are many significant correlations among different nutrients. The valuable information is very useful in biofortification breeding and functional food development.
Authors:Diandou Xu, Zhi Zhang, Qiaolong Jiang, Yifan Li and Zhifang Chai
Passive air samplers (polyurethane foam disks) were deployed at 25 urban sites and 66 rural sites over the period of July
to October 2005, partly between October 2005 and January 2006 for about 120 days across China, and analyzed for extractable
organo-chlorine /-bromine /-iodine (EOCl/EOBr/EOI) and polychlorinated biphenyls (PCBs) using hybrid neutron activation analysis
(NAA) combined with gas chromatographymass spectrometry (GC-MS). The average concentration of EOCl, EOBr, EOI and ΣPCBs among
all the sites were 173.7, 3.5, 1.0 and 0.74 ng/d, respectively. Higher values of EOCl/Br/I and PCBs were detected in the areas
of high usage and high emission, which were linked to relatively high-income areas in China, while lower in the west ill-developed
region of China, which indicated that these pollutants mainly came from industrial pollution. Higher EOCl contents in traffic
areas stated that the exhaust emission from vehicle was another main source of organochlorines in the air. The relative proportions
of the known organochlorines (84 PCB congeners) to total EOCl were 0.02–3.0%, which implied that most of EOCl measured in
air were unknown.
Authors:Ping Zhou, Z. Wang, Y. Xu, Lei Zhang and Y. Wang
Uranyl luminescences in phosphoric acid system has been studied. Uranyl excited by a nitrogen laser shows single or biexponential luminescence decays in the phosphoric acid system. When the uranyl ion or phosphoric acid concentration are lower, a single exponential luminescence decay appears, whereas at higher uranyl ion or phosphoric acid concentrations, biexponential decay is observed. Time-resolved spectra of uranyl in this system are measured. The reasons of the phenomena are tentatively established.