Chemical characterisation of marine aerosol at Amsterdam Island during the austral summer of 2006–2007

Atmospheric aerosols were collected in separate fine (<2.5 μm) and coarse (>2.5 μm) size fractions in the period December 2006–March 2007 at Amsterdam Island in the southern Indian Ocean. A major objective of the study was to assess biogenic impact on the marine aerosol. The samples were analysed for organic carbon, water-soluble organic carbon, major inorganic ionic species, and organic species, including methanesulphonate (MSA), dicarboxylic acids, and organosulphates. The concentrations of sea salt, non-sea-salt sulphate, and water-soluble and water-insoluble organic matter (WSOM and WIOM) were estimated. Sea salt dominated the composition of the aerosol and accounted for 83% and 91% of the sum of the mass of the four aerosol types in the fine and coarse size fractions, respectively. WSOM, which can serve as a proxy for biogenic secondary organic aerosol (SOA), accounted for only 2.8% of the sum of the mass of the four aerosol types in the fine size fraction. MSA was the dominating organic compound with a median concentration of 47 ng m^?3. The organosulphates were characterised as sulphate esters of hydroxyl acids and a dihydroxylaldehyde, which may originate from the oxidation of algal/bacterial unsaturated fatty acid residues. No evidence was found for isoprene SOA.     

天然产物Penicilliazine类似物的合成

以7-甲氧基-4,4a,5,6,8a-五氢-1,2-苯并口恶嗪-3-羧酸乙酯(1a)为起始原料,经NaOH醇溶液和酸化处理,再通过二甲基氨基吡啶(DMAP)催化、1,3-双环己基碳二亚胺(DCC)脱水与7,8-二甲氧基-3-羟基-2(1氢)-喹诺酮(2)的酯化反应,成功合成了天然产物Penicilliazine的类似物P-1,总收率为54.4%,用1HNMR、13CNMR、MS和元素分析等对P-1进行了结构表征;对DCC投料量等反应条件进行了初步优化;对水解反应过程的研究发现,烯醇醚结构的化合物1a可水解失去甲基得到酮式结构的化合物7-羰基-4,4a,5,6,8,8a-六氢-1,2-苯并口恶嗪-3-羧酸(1c),而使用酮式结构1c的乙酯,未发现相应酮式结构羧酸1c的生成。     

The adaptive chirplet transform and visual evoked potentials

We propose a new approach based upon the adaptive chirplet transform (ACT) to characterize the time-dependent behavior of the visual evoked potential (VEP) from its initial transient portion (tVEP) to the steady-state portion (ssVEP). This approach employs a matching pursuit (MP) algorithm to estimate the chirplets and then a maximum-likelihood estimation (MLE) algorithm to refine the results. The ACT decomposes signals into Gaussian chirplet basis functions with four adjustable parameters, i.e., time-spread, chirp rate, time-center and frequency-center. In this paper, we show how these four parameters can be used to distinguish between the transient and the steady-state phase of the response. We also show that as few as three chirplets are required to represent a VEP response. Compared to decomposition with Gabor logons, a more compact representation can be achieved by using Gaussian chirplets. Finally, we argue that the adaptive chirplet spectrogram gives a superior visualization of VEP signals' time-frequency structures when compared to the conventional spectrogram.     

On-Line Control of Polymer Addition to Prevent Massive Sludge Washout

An experimental method that quantifies the effect of polymer dosing on sludge settling characteristics is proposed. This method consists of recording batch settling curves at a grid of sludge and polymer concentrations. The effect of the polymer was found to depend on the mixing time between the dosing of the polymer and the start of the batch sedimentation. The recorded effects could be successfully implemented in a 1D dynamic settler model. From the literature it was concluded that keeping the sludge blanket below a certain critical height is an effective way of controlling the effluent suspended solids. From a model-based analysis this strategy appeared to be sound. Different control strategies using, respectively, the sludge blanket height [feedback (FB)], the hydraulic loading [feedforward (FF)], the solids loading (FF), or the sludge volume loading (FF) were tested for their ability to keep the sludge blanket below the critical height. The control strategy based on the hydraulic loading was the least efficient with respect to minimizing polymer dosage. The others appeared equally effective provided that they were properly tuned. Using the excess of the critical sludge blanket height as a measure of effectiveness, strategies based on more than one measured variable appeared to be less sensitive to suboptimal tuning.     

Bioaugmenting bioreactors for the continuous removal of 3-chloroaniline by a slow release approach

The survival and activity of microbial degradative inoculants in bioreactors is critical to obtain successful biodegradation of non- or slowly degradable pollutants. Achieving this in industrial wastewater reactors is technically challenging. We evaluated a strategy to obtain complete and stable bioaugmentation of activated sludge, which is used to treat a 3-chloroaniline (3-CA) contaminated wastewater in a lab-scale semi-continuous activated sludge system. A 3-CA metabolizing bacterium, Comamonas testosteroni strain I2, was mixed with molten agar and encapsulated in 4 mm diameter open-ended silicone tubes of 3 cm long. The tubes containing the immobilized bacteria represented about 1% of the volume of the mixed liquor. The bioaugmentation activity of a reactor containing the immobilized cells was compared with a reactor with suspended I2gfp cells. From day 25-30 after inoculation, the reactor with only suspended cells failed to completely degrade 3-CA because of a decrease in metabolic activity. In the reactors with immobilized cells, however, 3-CA continued to be removed. A mass balance indicated that ca. 10% of the degradation activity was due to the immobilized cells. Slow release of the growing embedded cells from the agar into the activated sludge medium, resulting in a higher number of active 3-CA-degrading I2 cells, was responsible for ca. 90% of the degradation. Our results demonstrate that this simple immobilization procedure was effective to maintain a 3-CA-degrading population within the activated sludge community.     

Sonic spray ionization technology: performance study and application to a LC/MS analysis on a monolithic silica column for heroin impurity profiling

Sonic spray (SS) ionization is a relatively novel atmospheric pressure ionization technique for LC/MS, based on the principle of "spray ionization", which only recently became commercially available. In this paper, we evaluate the performance of this ion source as an interface for LC/MS in comparison with the more traditional and better studied pneumatically assisted electrospray or ion spray (IS). The effect of organic modifiers, volatile acids, and buffer systems in the LC eluent on the ionization efficiency of both interfaces is described and some possible explanations for the observed phenomena are highlighted. We could conclude that the presence of organic solvents gradually increased the ionization efficiency for IS and SS, while volatile acids or buffers gave a significant signal suppression. Furthermore, we present the application of the sonic spray interface to a fast LC/MS analysis, for the simultaneous determination of the seven prime opium alkaloids in heroin impurity profiling. Chromatographic separation is performed in 5 min on a monolithic silica column (Chromolith Performance) with a gradient elution system and an optimized flow of 5 mL/min. By means of a postcolumn split of approximately 1/20, a coupling between the fast LC system and the mass spectrometer is made. The method is validated and successfully applied to the analysis of real-time seized heroin street samples.     

Less Is Sometimes More: Goal Content Matters.

According to expectancy-value theories, increasing the utility value of a learning activity should result in higher motivation and better learning. In contrast, self-determination theory posits that the content of the future goals (intrinsic vs. extrinsic) that enhance the utility value of the learning activity needs to be considered as well. Contrast-cell analyses of an experimental study showed that double goal framing (intrinsic plus extrinsic) facilitated a mastery orientation, performance, and persistence and decreased a performance-approach orientation compared with extrinsic goal framing. However, double goal framing resulted in a less optimal pattern of outcomes compared with intrinsic goal framing, suggesting that the content of the provided goals matters. Goal content effects on both performance and persistence were fully mediated by mastery orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On efficient simulation of non-Newtonian flow in saturated porous media with a multigrid adaptive refinement solver

Flow of non-Newtonian fluid in saturated porous media can be described by the continuity equation and the generalized Darcy law. Here we discuss the efficient solution of the resulting second order nonlinear elliptic equation. The equation is discretized by the finite volume method on a cell-centered grid. Local adaptive refinement of the grid is introduced in order to reduce the number of unknowns. We develop a special implementation, that allows us to perform unstructured local refinement in conjunction with the finite volume discretization. Two residual based error indicators are exploited in the adaptive refinement criterion. Second order accurate discretization of the fluxes on the interfaces between refined and non-refined subdomains, as well as on the boundaries with Dirichlet boundary condition, are presented here as an essential part of an accurate and efficient algorithm. A nonlinear full approximation storage multigrid algorithm is developed especially for the above described composite (coarse plus locally refined) grid approach. In particular, second order approximation of the fluxes around interfaces is a result of a quadratic approximation of slave nodes in the multigrid-adaptive refinement (MG-AR) algorithm. Results from numerical solution of various academic and practice-induced problems are presented and the performance of the solver is discussed.     

Multi-variable sensitivity and identifiability analysis for a complex environmental model in view of integrated water quantity and water quality modeling

Environmental models are often over-parameterized. A sensitivity analysis can identify influential model parameters for, e.g. the parameter estimation process, model development, research prioritization and so on. This paper presents the results of an extensive study of the Latin-Hypercube-One-factor-At-a-Time (LH-OAT) procedure applied to the Soil and Water Assessment Tool (SWAT). The LH-OAT is a sensitivity analysis method that can be categorized as a screening method. The results of the sensitivity analyses for all output variables indicate that the SWAT model of the river Kleine Nete is mainly sensitive to flow related parameters. Rarely, water quality parameters get a high priority ranking. It is observed that the number of intervals used for the Latin-Hypercube sampling should be sufficiently high to achieve converged parameter rankings. Additionally, it is noted that the LH-OAT method can enhance the understanding of the model, e.g. on the use of water quality input data.