Predicting bioavailability of PAHs in field-contaminated soils by passive sampling with triolein embedded cellulose acetate membranes

Triolein embedded cellulose acetate membrane (TECAM) was used for passive sampling of the fraction of naphthalene, phenanthrene, pyrene and benzo[a]pyrene in 18 field -contaminated soils. The sampling process of PAHs by TECAM fitted well with a first-order kinetics model and PAHs reached 95% of equilibrium in TECAM within 20 h. Concentrations of PAHs in TECAM (C-TECAM) correlated well with the concentrations in soils (r(2) = 0.693-0.962, p < 0.001). Furthermore. concentrations of PAHs determined in the soil solution were very close to the values estimated by C-TECAM and the partition coefficient between TECAM and water (KTECAM-W). After lipid normalization nearly 1:1 relationships were observed between PAH concentrations in TECAMs and earthworms exposed to the soils (r(2) = 0.591-0.824, n = 18, p < 0.01). These results suggest that TECAM can be a useful tool to predict bioavailability of PAHs in field-contaminated soils. (C) 2008 Elsevier Ltd. All rights reserved

Deriving Effective Energy Loss Function for Silver from XPS Spectrum

AbstractXPS spectra of silver excited by synchrotron irradiation with energy same as Al Kα X-ray has been measured. After filtering spectrum noise, the inelastic background starting from the lower binding energy of photoelectrons is removed by an iteration procedure. The energy loss spectrum for a single sub-shell photoelectron is then extracted from the Ag 3p XPS spectrum. Based on this single sub-shell photoelectron energy loss spectrum the effective energy loss function (EELF) is obtained by the extended Landau approach. Monte Carlo simulation with the derived EELF can reproduce well the experimental XPS spectrum

b \to ss\bar{d}$ in a Vector Quark Model

The rare decay $b\to ss\bar{d}$ is studied in a vector quark model by adding the contributions from exotic vector-like quarks. We find that the contribution from box diagrams amounts to $10^{-9}$ in the branching ratio, while the $Z$-mediated tree level contribution is negligible.Comment: LaTeX, 9 pages with 1 figur

Evidencia experimental de la abundancia de bacterias del suelo como el principal iniciador del efecto de preparación de la rizosfera

Se piensa que las comunidades microbianas del suelo son responsables del efecto de preparación de la rizósfera (RPE). Sin embargo, desde que las comunidades microbiales están compuestas de diversos componentes, se conoce muy poco acerca de cuál es el componente que tiene el rol principal en dicho efecto. En este estudio, se hicieron crecer soja y algodón en dos lugares a diferentes latitudes con diferentes condiciones de luz y temperatura in situ. Se cuantificó RPE usando un método natural de δC13 y se midió la abundancia, riqueza y composición de las comunidades de hongos y bacterias con métodos moleculares basados en el ADN. Entre todas las variables potenciales, incluyendo los tres índices de comunidades de hongos y bacterias anteriormente mencionados, e índices vegetales y físico-químicos del suelo, se mostró que la abundancia de bacterias explicó una gran proporción de la variación en RPE. Nuestro estudio identificó el mecanismo biológico que subyace este importante proceso ecológico.Soil microbial communities are thougth to be responsible for the rhizosphere priming effect (RPE). However, because soil microbial communities are comprised of diverse components, very little is known about which component plays the critical role. Here, soybean and cottonwood were grown at two latitudinal locations with different temperature and light conditions in-situ. We quantified RPE using a natural 13C method, and measured the abundance, richness and composition of bacteria and fungi communities with DNA-based molecular methods. Among all potential variables, including the three aforementioned indexes of bacteria and fungi communities and soil physiochemical and plant indexes, bacterial abundance was found to explain a large proportion of variation in RPE. Our study identified the biological mechanism underlying this important ecological process.Fil: Ma, Y.P.. Chinese Academy of Sciences. Institute of Applied Ecology; China. Chinese Academy of Agricultural Sciences. Institute of Environment and Sustainable Development in Agriculture. Key Laboratory of Dryland Agriculture;; China. University of Chinese Academy of Science; ChinaFil: Zhang, Z.J.. Chinese Academy of Sciences. Institute of Applied Ecology; China. Chinese Academy of Agricultural Sciences. Institute of Environment and Sustainable Development in Agriculture. Key Laboratory of Dryland Agriculture;; ChinaFil: Su, T.Q.. Chinese Academy of Sciences. Institute of Applied Ecology; ChinaFil: Busso, Carlos Alberto. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Johnston, E.R.. Georgia Institute of Technology. School of Civil and Environmental Engineering; Estados UnidosFil: Han, X.G.. Chinese Academy of Sciences. Institute of Applied Ecology; China. Chinese Academy of Sciences. Institute of Botany. State Key Laboratory of Vegetation and Environmental Change; ChinaFil: Zhang, X.M.. Chinese Academy of Agricultural Sciences. Institute of Environment and Sustainable Development in Agriculture. Key Laboratory of Dryland Agriculture;; Chin

Influence of Different Preparation Processes on the Mechanical Properties of Carbon Nanotube-Reinforced Copper Matrix Composites

Experiments on the uniform distribution of carbon nanotubes in the copper matrix using different ball milling methods were performed. The effect of different preparation processes for carbon nanotube (CNT)-reinforced copper matrix composites on their conductivity and mechanical properties was also analyzed. High-performance carbon nanotube-reinforced copper matrix composites containing 1 vol.% CNT by the best preparation process termed flake ball milling (FBM) possess good interface bonding strength not only with CNT evenly dispersed in the copper matrix but also with the CNT morphology and structure having the utmost integrity. Tensile strength increased by 30% with an elongation of 26% and electrical conductivity of 85% IACS as compared to a pure copper block prepared from the same FBM powders.Выполнены эксперименты по оценке равномерности распределения углеродных нанотрубок в медной матрице с использованием разных методов размола в шаровой мельнице. Проанализировано влияние различных методов изготовления композиционных материалов с медной матрицей, упрочненных углеродными нанотрубками, на их электропроводность и механические свойства. Высококачественные композиционные материалы (содержат 1 об.% углеродных нанотрубок), изготовляемые наиболее эффективным способом, получившим навание размол в шаровой мельнице для придания пластинчатой структуры , приобретают хорошую прочность сцепления на поверхности контакта не только при равномерном распределении углеродных нанотрубок в медной матрице, но и при максимальной целостности их морфологии и структуры. Предел прочности при растяжении возрастал на 30% при удлинении 26% и электропроводности 85% по стандарту IACS по сравнению с заготовкой из чистой меди, изготовленной из тех же пластинчатых порошков

Serum sialylation changes in cancer

Proteomic

Nanotribological Investigation of Polymer Brushes with Lithographically Defined and Systematically Varying Grafting Densities.

Following controlled photodeprotection of a 2-nitrophenylpropyloxycarbonyl-protected (aminopropyl)triethoxysilane (NPPOC-APTES) film and subsequent derivatization with a bromoester-based initiator, poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC) brushes with various grafting densities were grown from planar silicon substrates using atom transfer radical polymerization (ATRP). The grafting density correlated closely with the extent of deprotection of the NPPOC-APTES. The coefficient of friction for such PMPC brushes was measured by friction force microscopy in water and found to be inversely proportional to the grafting density due to the osmotic pressure that resists deformation. Deprotection of NPPOC-APTES via near-field photolithography using a range of writing rates enabled the fabrication of neighboring nanoscopic polymeric structures with dimensions ranging from 100 to 1000 nm. Slow writing rates enable complete deprotection to occur; hence, polymer brushes are formed with comparable thicknesses to macroscopic brushes grown under the same conditions. However, the extent of deprotection is reduced at higher writing rates, resulting in the concomitant reduction of the brush thickness. The coefficient of friction for such polymer brushes varied smoothly with brush height, with lower coefficients being obtained at slower writing rate (increasing initiator density) because the solvated brush layer confers greater lubricity. However, when ultrasharp probes were used for nanotribological measurements, the coefficient of friction increased with brush thickness. Under such conditions, the radius of curvature of the tip is comparable to the mean spacing between brush chains, allowing the probe to penetrate the brush layer leading to a relatively large contact area