Authors:S. Landsberger, P. Zhang, D. Wu, and A. Chatt
During the past decade we have determined the concentrations of a variety of trace elements in the Arctic aerosol by using themal and epithemal neutron activation analysis (NAA). More recently we have employed Compton suppression NAA to lower the detection limits for radionuclides that are characteristic of single or mainly single gamma-ray emission. Using these various methods, we have been able to use elements such as indium and silicon. Furthermore we have achieved extremely low detection limits for iodine, arsenic and antimony. The usefulness of these NAA methods are discussed in a large sampling program that incorporates more than one thousand samples.
Authors:M. Deibel, S. Landsberger, D. Wu, and W. Ehmann
Copper (Cu) is an essential element and is incorporated in many biomolecules that are involved in protecting the brain from oxidative damage. Many brain regions strongly affected by neurodegene rative diseases are small. A sensitive nondestructive procedure to determine Cu is desirable to preserve samples for additional studies. Copper is not easily determined by instrumental neutron activation analysis (INAA) due to high activity levels produced by major abundance elements such as sodium (Na) and chlorine (Cl), which produce a high Compton background. An INAA method involving a short epithermal neutron irradiation and counting with a Compton suppression system was developed to determine Cu in brain, via 5.1-min66Cu. These short irradiation results are compared to those based on coincidence spectrometry of annihilation photons from positron emitting 12.7-h64Cu after a long irradiation.
The aim of this study is to investigate the melting/freezing characteristics of paraffin by adding Cu nanoparticles. Cu/paraffin composite phase change materials (PCMs) were prepared by a two-step method. The effects of Cu nanoparticles on the thermal conductivity and the phase change heat transfer of PCMs were investigated by the Hot Disk thermal constants analyzer and infrared monitoring methods, respectively. The maximum thermal conductivity enhancements up to 14.2% in solid state and 18.1% in liquid state are observed at the 2 wt% Cu/paraffin. The photographs of infrared monitoring suggest that the melting and freezing rates of Cu/paraffin are enhanced. For 1 wt% Cu/paraffin, the melting and freezing times can be saved by about 33.3 and 31.6%, respectively. The results provide that adding nanoparticles is an efficient way to enhance the phase change heat transfer of PCMs.
The combustion energy of thioproline was determined
by the precision rotating-bomb calorimeter at 298.15 K to be ΔcU= –2469.301.44 kJ mol–1.
From the results and other auxiliary quantities, the standard molar enthalpy
of combustion and the standard molar enthalpy of formation of thioproline
were calculated to be ΔcHmθC4H7NO2S,
(s), 298.15 K= –2469.921.44 kJ mol–1
and ΔfHmθC4H7NO2S, (s), 298.15K= –401.331.54
Authors:D. Zhou, H. Gong, Z. Luan, J. Hu, and F. Wu
The study site is the Honghe National Nature Reserve, a Ramsar designated site on the Sanjiang Plain in Northeast China. We present results regarding the spatial pattern and structure of plant communities in these most important natural but continually diminishing freshwater wetlands of China to help promote both protection and restoration. By investigating three ecological levels (landscape, ecosystem and community), this paper quantifies the characteristics of spatial pattern with the aim to identify specific ecological correlations with different hydrogeomorphic features. Specifically, the research involves hierarchical mapping of vegetation types by use of remote sensed data, and the coupling of landscape indices with fluvial topographic zones that have been deduced by GIS from DEM. Statistics from historical survey data are also used to measure the degradation of marshes as well as the historical change of the hydrological regime. We found that dominant is the
Calamagrostis angustifolia — Carex
spp. community type, a wet meadow and marsh complex within the prevailing landscape mosaic of shrubland and meadow. The results suggest that the sites’ hydro-geomorphic character has decisive influence on plant community structure and composition. There is only limited direct human interference in the sites and, as a consequence, the spatial pattern of vegetation distribution is natural. However, changes to the hydrological regime as the result of extensive irrigation activity in the surrounding area has led to rapid degradation of marsh wetlands within the sites, which threatens the ecological status in this storehouse of “Natural Genes” in the reserve.
The present study was performed to investigate the effect of β-aminobutyric acid (BABA) treatment on defence activation in grape berries and to analyse its cellular mechanism. The results implied that BABA treatment at an effective concentration of 20 mM significantly inhibited gray mould rot caused by Botrytis cinerea in grape berries by inducing resistance. Accordingly, 20 mM BABA triggered a priming defence in grape suspension cells, since only the BABA-treated cells exhibited an accelerated ability for augmenting defence responses upon the pathogen inoculation. The primed cellular reactions were related to an early H2O2 burst, prompt accumulation of stilbene phytoalexins and activation of PR genes. Thus, we assume that 20 mM BABA can induce resistance to B. cinerea infection in intact grape berries perhaps via intercellular priming defence. Moreover, the BABA-induced priming defence is verified, because no negative effects on cell growth, anthocyanin synthesis, and quality impairment in either grape cells or intact berries were observed under low pathogenic pressure.
The catalytic and accelerating effects of three coal-burning additives (CBA) on the burning of graphite were studied with
the help of thermogravimetric (TG) analysis. The kinetic study on the catalytic oxidation of the graphite doped with CBA was
carried out and the results were presented. The results show that the CBA can change the carbon oxidation/combustion course
by catalytic action and change the activation energy, thus improving the combustion efficiency.
Authors:J. Wu, H. Xing, D. Tang, Y. Gao, X. Yin, Q. Du, X. Jiang, and D. Yang
The method of high-performance liquid chromatography (HPLC) with diode array detector (DAD) was used and validated for the simultaneous determination of nine flavonoids (rutin, myricetin, quercitrin, quercetin, luteolin, genistein, kaempferol, apigenin, and isorhamnetin) in beagle dog plasma. Plasma sample was pre-treated with acetonitrile (containing 0.05% formic acid). Chromatographic separation was performed on a kromasil C18 column (250 × 4.6 mm, 5 µm) maintained at 35 °C. The mobile phase was a mixture of methanol and 0.2% formic acid with a step linear gradient. At 1.0 mL min−1 flow rate, the eluent of other eight flavonoids was detected simultaneously at 360 nm with good separation except genistein (detected at 254 nm). Under optimum conditions, the correlation coefficient between the peak area and the concentrations for each analyte was all above 0.999. The intra-day and inter-day precisions were less than 10% for all analytes. The limit of detection and the limit of quantification for the selected nine flavonoids were 0.006–0.03 and 0.02–0.12 g mL−1, respectively. The extracted recoveries of selected nine flavonoids were 74.02%–99.37%. The assay has been successfully applied to determine concentrations of nine flavonoids in plasma from beagle dog after being intravenously administrated Ginkgo biloba extract.
Authors:Z. Wu, A. Zhang, D. Shen, M. Leland, F. W. Harris, and S. Z. D. Cheng
Three aromatic polyimides based on 3,3′,4,4′-biphenyl-tetracarboxylic dianhydride (BPDA) and three different diamines 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (PFMB), 2,2′-dimethyl-4, 4′-diaminophenyl (DMB) or 3,3′-dimethylbenzidine (OTOL) have been synthesized. These polyimides are soluble in hotp-chlorophenol,m-cresol or other phenolic solvents. Fibers have been spun from isotropic solutions using a dry-jet wet spinning method. The as-spun fibers generally exhibit low tensile properties, and can be drawn at elevated temperatures (>380° C) up to a draw ratio of 10 times. Remarkable increases in tensile strength and modulus are achieved after drawing and annealing. The crystal structures of highly drawn fibers were determinedvia wide angle X-ray diffraction (WAXD). The crystal unit cell lattices have been determined to be monoclinic for BPDA-PFMB and triclinic for both BPDA-DMB and BPDA-OTOL. Thermomechanical analysis (TMA) was used to measure thermal shrinkage stress and strain. A selfelongation has been found in the temperature region around 450°C. This phenomenon can be explained as resulting from the structural development in the fibers as evidencedvia WAXD observations.
Authors:D. Huang, H. Zhang, M. Tar, Y. Zhang, F. Ni, J. Ren, D. Fu, L. Purnhauser, and J. Wu
Stripe or yellow rust (Yr), caused by Puccinia striiformis Westend. (Pst), is one of the most important wheat diseases worldwide. New aggressive Pst races can spread quickly, even between countries and continents. To identify and exploit stripe rust resistance genes, breeders must characterize first the Pst resistance and genotypes of their cultivars. To find new sources of resistances it is important to study how wheat varieties respond to Pst races that predominate in other continents. In this study we evaluated stripe rust resistance in 53 Hungarian winter wheat cultivars in China. Twenty-four cultivars (45.3%) had all stage resistance (ASR) and 1 (1.9%) had adult-plant resistance (APR), based on seedling tests in growth chambers and adult-plant tests in fields. We molecularly genotyped six Yr resistance genes: Yr5, Yr10, Yr15, Yr17, Yr18, and Yr36. Yr18, an APR gene, was present alone in five cultivars, and in ‘GK Kapos’, that also had seedling resistance. The other five Yr genes were absent in all cultivars tested.