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Abstract  

The objective of this study is to conduct a bibliometric analysis of all biological invasions-related publications in the Science Citation Index (SCI) from 1991 to 2007. The indicator citation per publication (CPP) was used to evaluate the impact of articles, journals, and institutions. In the 3323 articles published in 521 journals, 7261 authors from 1905 institutions of 100 countries participated. As the most productive country of biological invasions research, the US will benefit from more collaboration between institutions, countries, and continents. In addition, analysis of keywords was applied to reveal research trends.

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Abstract  

Power-time curves and metabolic properties of Tetrahymena thermophila BF5 exposed to different Yb3+ levels were studied by ampoule method of isothermal calorimetry at 28°C. Metabolic rate (r) decreased significantly while peak time (PT) increased with the increase of Yb3+. These results were mainly due to the inhibition of cell growth, which corresponded to the decrease of cell number obtained by cell counting. Compared with cell counting, calorimetry was sensible, easy to use and convenient for monitoring the toxic effects of Yb3+ on cells and freshwater ecosystem. It was also found that cell membrane fluidity decreased significantly under the effects of Yb3+, which indicated that Yb3+ could be membrane active molecules with its effect on cell membranes as fundamental aspect of its toxicity.

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Abstract  

The crystal structure, melting range, decomposition temperature, solubilities in aqueous and organic phase, and distribution ratio in biphase system of N,N,N′,N′-tetramethyl diglycolamide (TMDGA) have been studied in the present work. Water-soluble TMDGA with very low solubility in kerosene or 30 % trialkyl phosphine (TRPO)/kerosene meets the primary requirement to act as the stripping agent in TRPO process which has been developed for actinides partitioning from high level waste. Slope analysis, electrospray ionization mass spectrometry (ESI–MS) and spectrophotometric titration indicate that in weak and moderate acidic aqueous solution, up to three TMDGA molecules form complexes with Zr4+, trivalent lanthanides (Ln3+), trivalent actinides (An3+) or tetravalent actinides (An4+). Their complex formation constants determined by liquid–liquid extraction method follow the order predicted by the electrostatic model of 4f and 5f elements and the covalent model of 4d transition elements: Ln3+ ~ An3+ < An4+ ≪ Zr4+. Hydrolysis of actinide cations, especially An4+, in the media of low acidity, reduces the complexation stability. In addition, the effect of aqueous acidity and temperature has been investigated. No obvious influence of temperature on Np4+ complexes has been found. However, the influence on Am3+ and Pu4+, especially on their 1:1 or 1:2 complex species with TMDGA, is relatively considerable. Strong affinity of TMDGA to An3+ and An4+ implies that TMDGA has potential to strip An3+ and An4+ from TRPO.

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To detect and identify natural antioxidants in Swertia chirayita with protective effect against cerebral infarction, a screening method, using column chromatography and cerebral ischemia-reperfusion injury in rat, was developed. Seventeen compounds were purposefully separated and identified by Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy, Ultraviolet Spectrum, and Mass Spectrometry. The purified compounds were further screened by radical scavenging activity and cerebral ischemia-reperfusion injury in rats. Two compounds showed apparent radical scavenging activity and neuroprotective activity. The two compounds were identified as 1-hydroxy-2,3,4,6-tetramethoxyxanthone and 1,5,8-trihydroxy-3-methoxy xanthone, and were preliminarily considered as primary natural neuroprotective antioxidants in Swertia chirayita. These two compounds (20 mg kg−1) markedly decreased infarct size to below 5%, and also caused a significant improvement of activities of superoxide dismutase (SOD) (92.90 ± 11.19 U ml−1), glutathione peroxidase (GSH-Px) (122.58 ± 12.31 μmol mg−1) and a decrease in the content of malondialdehyde (MDA) (3.98 ± 2.00 nmol ml−1) in serum. The two compounds showed strong capability for protective effects against cerebral damages induced by ischemia-reperfusion, and the protective effect may be related to the inhibition of lipid peroxidation. The use of the screening method based on tracing separation and ischemia reperfusion would provide a new way for detection of radical-scavenging and natural neuroprotective compounds from Swertia chirayita or complex matrices.

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Abstract  

This study of photodegradation of the antibiotic chloromycetin (Cm) in aqueous solution by direct and indirect photolysis included photolysis under UV-C light (λ = 254 nm) and photo-oxidation under UV–vis light (λ ≥ 365 nm) in the presence of iron and humic acid. The factors affecting Cm degradation were studied and are described in detail, including initial pH, ionic strength and initial concentrations of iron and humic acid. Results showed that a degradation efficiency up to 90% was achieved by direct photolysis of Cm at pH 5–7 and the calculated quantum yield was 0.084. Higher salt content (NaCl, 0.01–0.5 M) was found to benefit direct photolysis. Indirect photolysis of Cm in the presence of iron(III) formed OH radicals at pH ~ 3. Under UV–vis light, increased pH resulted in a significant decrease in the efficiency of indirect photolysis. Direct and indirect photolysis reactions both followed a pseudo first-order kinetic law. Humic acid tended to inhibit the photodegradation of Cm under the conditions of this work, implying that photosensitization of humic acid did not play any role in the photodegradation.

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Abstract

Biomass pyrolysis can be divided into three stages: moisture evaporation, main devolatilization, and continuous slight devolatilization. This present study focuses on the heat and mass transfer characteristics of biomass in the first pyrolysis stage, which takes place in the range of room temperature to 150 °C. Thermalgravimetric experiments of rice husk and cotton stalk were performed by a synchronic thermal analyzer (TG/DSC). Four nonisothermal drying models were obtained from common isothermal drying models in order to describe the drying behavior of agricultural products. The moisture content of biomass decreased rapidly as the temperature increased and an apparent water loss peak was observed in the temperature range of 65–75 °C. DSC could be regarded as the superposition of three parts: heat flow from moisture evaporation, heat flow from the heat capacity of unevaporated moisture, and heat flow from the heat capacity of dry base biomass. The heat requirements for the dehydration of 1 kg rice husk and cotton stalk were 251 and 269 kJ, respectively. Nonisothermal drying models were evaluated based on the coefficient of determination (R 2) and reduced chi-square (χ2). Page model was found to be the best for describing the nonisothermal drying kinetics. The values of activation energy were determined to be 9.2 and 15.1 kJ/mol for rice husk and cotton stalk, respectively.

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Abstract

Anisodus tanguticus (Maxim.) Pascher is an important Tibetan folk medicine and the source of tropane alkaloids (TAs) grown in Qinghai-Tibet Plateau. There are marked differences in quality of A. tanguticus from geographic areas. The aim of present research was to establish a method for the quantitative analysis of TAs coupled with chemometrics analysis to trace geographical origins. Qualitative analysis of TAs in A. tanguticus was carried out using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and quantitative analysis of TAs in different plant organs from different geographical origin was achieved. Contents of TAs were subjected to the principal component analysis, and orthogonal partial least-squares discriminant analysis. The contents of the three marker compounds (anisodamine, anisodine and atropine) in the roots and acrial parts of A. tanguticus were positive correlated and varied significantly from different geographical origins. Principal component analysis, and orthogonal partial least-squares discriminant analysis results showed excellent discrimination between different geographical origin of A. tanguticus. This study could provide comprehensive evaluation and further utilization of A. tanguticus resources.

Open access
Journal of Radioanalytical and Nuclear Chemistry
Authors: Zhen Chen, Huan Meng, Hui Yuan, Gengmei Xing, Chunying Chen, Feng Zhao, Yun Wang, Chengcheng Zhang, and Yuliang Zhao

Abstract  

Nanosized copper particles are widely used in fields of lubricants, polymers/plastic, metallic coating and ink. Recently, we found that copper particles in different sizes can lead to different toxicological effects. To clarify the target organs of copper particles of different sizes, the inductively coupled plasma mass spectroscopy (ICP-MS) was employed to evaluate the distribution of copper in different organs of mice after a single dose oral exposure. The results suggest that the main target organs for copper nanoparticles are kidney, liver and blood. Liver is the main damaged organ.

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Abstract

Liquid organic peroxides (LOPs) have been widely used as initiators of polymerization, hardening, or cross-linking agents. We evaluated a beneficial kinetic model to acquire accurate thermokinetic parameters to help preventing runaway reactions, fires or explosions in the process environment. Differential scanning calorimetry was used to assess the kinetic parameters, such as kinetic model, reaction order, heat of reaction (ΔH d), activation energy (E a), frequency factor (lnk 0), etc. The non-isothermal and isothermal kinetic models were compared to determine the validity of the kinetic model, and then applied to the thermal hazard assessment of commercial package contaminated with LOPs. Simulations of a 0.5-L Dewar vessel and 25-kg commercial package were performed. We focused on the thermal stability of different liquid system properties for LOPs. From the results, the optimal conditions were determined for avoiding violent heat effects that can cause a runaway reaction in storage, transportation, and manufacturing.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Huan Meng, Zhen Chen, Gengmei Xing, Hui Yuan, Chunying Chen, Feng Zhao, Chengcheng Zhang, Yun Wang, and Yuliang Zhao

Abstract  

Recently, it was reported that the toxicity of copper particles increases with the decrease of the particle size on a mass basis. To understand this phenomenon, inductively coupled plasma mass spectrometry (ICP-MS) techniques and in vitro chemical studies were carried out to explore how they produce toxicity in vivo. The results suggest that when the sizes of particles become small and down to a nanoscale, copper becomes extremely reactive in a simulative intracorporeal environment. The nanosized copper particles consume the hydrogen ions in stomach more quickly than micron ones. These processes further convert the copper nanoparticles into cupric ions whose toxicity is very high in vivo.

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