bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavioral flexibility in prey selection by bacterivorous nanoflagellates
Authors: Jürgens Klaus , DeMott William R.
Published: May 2010

We used laboratory experiments to study the effects of changing food abundance on the selective feeding of two heterotrophic nanoflagellates on particles of similar size but differing nutritional quality (latex beads and fluorescently stained bacteria). Both Bodo saltans and Spumella sp. exhibited similar shifts in selectivity with changes in food concentration. Flagellates that were cultured under food‐limiting conditions showed a modest but significant preference for beads when both particles were offered simultaneously. However, both flagellates exhibited strong discrimination against the inert beads within 30–60 min after the addition of a satiating concentration of live bacteria. As bacterial abundance declined over 24 h, discrimination against the inert beads gradually relaxed. The observed pattern of concentration‐dependent selectivity is in agreement with the predictions of optimal diet models.
Marine boundary layer over the subtropical southeast Pacific during VOCALS-REx – Part 1: Mean structure and diurnal cycle
Authors: Rahn D. A. , Garreaud R.
Published: May 2010

Abstract. Atmospheric subsidence over the subtropical southeast Pacific (SEP) leads to a low-level anticyclonic circulation, a cool sea surface and a cloud-topped marine boundary layer (MBL). Observations in this region from a major field campaign during October and November 2008, the VOCALS Regional Experiment, provide ample data to characterize the lower atmospheric features over the SEP. The observations are also useful to test the ability of an area-limited, high-resolution atmospheric model to simulate the SEP conditions. Observations and model-results (where appropriate) improve the characterization of the mean state (Part 1) and variability (Part 2) of the lower troposphere including circulation, MBL characteristics and the upsidence wave. Along 20° S the MBL is generally deeper offshore (1600 m at 85° W) but there is also considerable variability. MBL depth and variability decrease towards the coast and maximum inversion strength is detected between 74–76° W. Weather Research and Forecasting (WRF) simulations underestimate MBL height the most near the coast but improve offshore. Southeasterly trades prevail within the MBL although the wind speed decreases toward the coast. Above the MBL along the coast of Chile, flow is northerly, has a maximum at 3 km, and extends westward to ~74° W, apparently due to the mechanical blocking exerted by the Andes upon the westerly flow aloft. Mean MBL features along northern Chile (18–25° S) are remarkably similar (e.g., MBL depth just below 1 km) in spite of different SST. Observed diurnal cycles of the temperature at the coast and further offshore exhibit a number of conspicuous features that are consistent with the southwestward propagation of an upsidence wave initiated during late evening along the south Peru coast. Furthermore, the passage of the vertical motion results in either constructive or deconstructive interference with the radiatively-forced diurnal cycle of MBL depth. Interference is clearly seen in the soundings at Iquique which are driven by a strong upsidence wave contrary to the radiation-driven cycle, leading to a diurnal cycle opposite of the other sites. Because WRF simulations have a lower MBL height, the speed of the simulated gravity wave is slower than observations and accounts for most of the discrepancy between observed and simulated phase speeds.
Marine boundary layer over the subtropical southeast Pacific during VOCALS-REx – Part 2: Synoptic variability
Authors: Rahn D. A. , Garreaud R.
Published: May 2010

Abstract. In the second part of this work we study the day-to-day variability of the marine atmospheric boundary layer (MBL) over the subtropical southeast Pacific using primarily results from a numerical simulation that covered the whole VOCALS-REx period (October–November 2008). In situ and satellite-derived observations of the MBL height in the offshore region indicate rapid, significant variations (from 500 m to 1700 m a.s.l. over a few days) during October. These MBL changes are connected with the passage of midlatitude troughs that altered the large-scale environment over the VOCALS-REx region. In contrast, the synoptic forcing and MBL changes were less prominent during November. Modelled and observed MBL depth at Point Omega (20° S, 85° W) compare quite well during October (but the simulation is on average 200 m lower) while in November the simulation does not perform as well. In the prognostic local MBL height equation the height change, the horizontal MBL height advection, and the large scale vertical velocity at MBL top are calculated explicitly from the simulation. The entrainment velocity is calculated as the residual of the other terms in the equation. While the vertical velocity and residual terms are opposing and generally have the largest magnitude on average, it is the variability in the advection that explains most of the large changes in the MBL depth. Examination of several cases during VOCALS-REx suggests that the advective term is in turn largely controlled by changes in wind direction, driven by midlatitude activity, acting on a MBL that generally slopes down toward the coast. In one phase, the subtropical anticyclone is reinforced and extends toward the Chilean coast, leading to easterly wind that advects low MBL heights from the coast as far as Point Omega. The opposite phase occurs after the passage of an extratropical cyclone over southern Chile, leading to southwesterly wind that advects a deeper MBL towards subtropical latitudes.
Characteristics of size distributions at urban and rural locations in New York
Authors: Bae M.-S. , Schwab J. J. , Hogrefe O. , Frank B. P. , Lala G. G. , Demerjian K. L.
Published: May 2010

Abstract. Paired nano- and long-tube Scanning Mobility Particle Sizer (SMPS) systems were operated for four different intensive field campaigns in New York State. Two of these campaigns were at Queens College in New York City, during the summer of 2001 and the winter of 2004. The other field campaigns were at rural sites in New York State. The data with the computed diffusion loss corrections for the sampling lines and the SMPS instruments were examined and the combined SMPS data sets for each campaign were obtained. The diffusion corrections significantly affect total number concentrations, and in New York City, affect the mode structure of the size distributions. The relationship between merged and integrated SMPS total number concentrations with the diffusion loss corrections and the CPC number concentrations yield statistically significant increases (closer to 1) in the slope and correlation coefficient compared to the uncorrected values. The measurements are compared to PM2.5 mass concentrations and ion balance indications of aerosol acidity. Analysis of particle growth rate in comparison to other observations can classify the events and illustrate that urban and rural new particle formation and growth are the result of different causes. Periods of low observed PM2.5 mass, high number concentration, and low median diameter due to small fresh particles are associated with primary emissions for the urban sites; and with particle nucleation and growth for the rural sites. The observations of high PM2.5 mass, lower number concentrations, and higher median diameter are mainly due to an enhancement of photochemical reactions leading to condensation processes in relatively aged air. There are statistically different values for the condensation sink (CS) between urban and rural areas. While there is good association (r2>0.5) between the condensation sink (CS) in the range of 8.35–283.9 nm and PM2.5 mass in the urban areas, there is no discernable association in the rural areas. The average values computed for the CS lie in the range 8.7×10−3–3.5×10−2 s−1.
Coupling aerosol surface and bulk chemistry with a kinetic double layer model (K2-SUB): oxidation of oleic acid by ozone
Authors: Pfrang C. , Shiraiwa M. , Pöschl U.
Published: May 2010

Abstract. We present a kinetic double layer model coupling aerosol surface and bulk chemistry (K2-SUB) based on the PRA framework of gas-particle interactions (Pöschl-Rudich-Ammann, 2007). K2-SUB is applied to a popular model system of atmospheric heterogeneous chemistry: the interaction of ozone with oleic acid. We show that our modelling approach allows de-convoluting surface and bulk processes, which has been a controversial topic and remains an important challenge for the understanding and description of atmospheric aerosol transformation. In particular, we demonstrate how a detailed treatment of adsorption and reaction at the surface can be coupled to a description of bulk reaction and transport that is consistent with traditional resistor model formulations. From literature data we have derived a consistent set of kinetic parameters that characterise mass transport and chemical reaction of ozone at the surface and in the bulk of oleic acid droplets. Due to the wide range of rate coefficients reported from different experimental studies, the exact proportions between surface and bulk reaction rates remain uncertain. Nevertheless, the model results suggest an important role of chemical reaction in the bulk and an approximate upper limit of ~10−11 cm2 s−1 for the surface reaction rate coefficient. Sensitivity studies show that the surface accommodation coefficient of the gas-phase reactant has a strong non-linear influence on both surface and bulk chemical reactions. We suggest that K2-SUB may be used to design, interpret and analyse future experiments for better discrimination between surface and bulk processes in the oleic acid-ozone system as well as in other heterogeneous reaction systems of atmospheric relevance.
Extreme events in total ozone over Arosa – Part 1: Application of extreme value theory
Authors: Rieder H. E. , Staehelin J. , Maeder J. A. , Peter T. , Ribatet M. , Davison A. C. , Stübi R. , Weihs P. , Holawe F.
Published: May 2010

Abstract. In this study ideas from extreme value theory are for the first time applied in the field of stratospheric ozone research, because statistical analysis showed that previously used concepts assuming a Gaussian distribution (e.g. fixed deviations from mean values) of total ozone data do not adequately address the structure of the extremes. We show that statistical extreme value methods are appropriate to identify ozone extremes and to describe the tails of the Arosa (Switzerland) total ozone time series. In order to accommodate the seasonal cycle in total ozone, a daily moving threshold was determined and used, with tools from extreme value theory, to analyse the frequency of days with extreme low (termed ELOs) and high (termed EHOs) total ozone at Arosa. The analysis shows that the Generalized Pareto Distribution (GPD) provides an appropriate model for the frequency distribution of total ozone above or below a mathematically well-defined threshold, thus providing a statistical description of ELOs and EHOs. The results show an increase in ELOs and a decrease in EHOs during the last decades. The fitted model represents the tails of the total ozone data set with high accuracy over the entire range (including absolute monthly minima and maxima), and enables a precise computation of the frequency distribution of ozone mini-holes (using constant thresholds). Analyzing the tails instead of a small fraction of days below constant thresholds provides deeper insight into the time series properties. Fingerprints of dynamical (e.g. ENSO, NAO) and chemical features (e.g. strong polar vortex ozone loss), and major volcanic eruptions, can be identified in the observed frequency of extreme events throughout the time series. Overall the new approach to analysis of extremes provides more information on time series properties and variability than previous approaches that use only monthly averages and/or mini-holes and mini-highs.
Extreme events in total ozone over Arosa – Part 2: Fingerprints of atmospheric dynamics and chemistry and effects on mean values and long-term changes
Authors: Rieder H. E. , Staehelin J. , Maeder J. A. , Peter T. , Ribatet M. , Davison A. C. , Stübi R. , Weihs P. , Holawe F.
Published: May 2010

Abstract. In this study the frequency of days with extreme low (termed ELOs) and extreme high (termed EHOs) total ozone values and their influence on mean values and trends are analyzed for the world's longest total ozone record (Arosa, Switzerland). The results show (a) an increase in ELOs and (b) a decrease in EHOs during the last decades and (c) that the overall trend during the 1970s and 1980s in total ozone is strongly dominated by changes in these extreme events. After removing the extremes, the time series shows a strongly reduced trend (reduction by a factor of 2.5 for trend in annual mean). Excursions in the frequency of extreme events reveal "fingerprints" of dynamical factors such as ENSO or NAO, and chemical factors, such as cold Arctic vortex ozone losses, as well as major volcanic eruptions of the 20th century (Gunung Agung, El Chichón, Mt. Pinatubo). Furthermore, atmospheric loading of ozone depleting substances leads to a continuous modification of column ozone in the Northern Hemisphere also with respect to extreme values (partly again in connection with polar vortex contributions). Application of extreme value theory allows the identification of many more such "fingerprints" than conventional time series analysis of annual and seasonal mean values. The analysis shows in particular the strong influence of dynamics, revealing that even moderate ENSO and NAO events have a discernible effect on total ozone. Overall the approach to extremal modelling provides new information on time series properties, variability, trends and the influence of dynamics and chemistry, complementing earlier analyses focusing only on monthly (or annual) mean values.
NO2 photolysis frequencies in street canyons
Authors: Koepke P. , Garhammer M. , Hess M. , Roeth E.-P.
Published: May 2010

Abstract. Photolysis frequencies for NO2 are modeled for the conditions in urban streets, which are taken into account as canyons with variable height and width. The effect of a street canyon is presented with absolute values and as a ratio RJ of the photolysis frequency within the street against those with free horizon, which allows further use of the existing photolysis parameterizations. Values are presented for variable solar elevation and azimuth angles, varying atmospheric conditions and different street properties. The NO2 photolysis frequency in the street, averaged over atmospheric conditions and street orientation, is reduced to less than 20% for narrow streets, to about 40% for typical urban streets, and only to about 80% for garden streets, each with about ±5% uncertainty. A parameterization of RJ with the global solar irradiance is given for values that are averaged over the meteorological conditions and the street orientation.
The definition of an atmospheric database for ADM-Aeolus
Authors: Marseille G. J. , Houchi K. , de Kloe J. , Stoffelen A.
Published: May 2010

Abstract. The definition of an atmospheric database is an important component of simulation studies in preparation of future earth observing remote sensing satellites. The ADM-Aeolus mission, scheduled for launch in medium 2012, aims at measuring wind profiles from the surface up to about 32 km with a global coverage. The vertical profile resolution is limited but may be changed during in-orbit operation. This provides the opportunity of a targeted sampling strategy, e.g., as a function of geographic region. Optimization of the vertical (and horizontal) sampling strategy requires a characterization of the atmosphere optical and dynamical properties, more in particular the distribution of atmospheric particles and their correlation with the atmospheric dynamics. The ADM-Aeolus atmospheric database combines meteorological data from the ECMWF model with atmosphere optical properties data from CALIPSO. An inverse algorithm to retrieve high-resolution particle backscatter from the CALIPSO level-1 attenuated backscatter product is presented. Global weather models tend to underestimate atmospheric wind variability. A procedure is described to ensure compatibility of the characteristics of the database winds with those from high-resolution radiosondes. The result is a high-resolution database of zonal, meridional and vertical wind, temperature, specific humidity and particle and molecular backscatter and extinction at 355 nm laser wavelength. This allows the simulation of small-scale atmospheric processes within the Aeolus observation sampling volume and their impact on the quality of the retrieved wind profiles. The database extends over four months covering all seasons. This allows a statistical evaluation of the mission components under investigaton. The database is currently used for the development of the ADM-Aeolus wind processing, the definition of wind calibration strategies and the optimization of the Aeolus sampling strategy.
Air-Sea CO2 fluxes in the Atlantic as measured during boreal spring and autumn
Authors: Padin X. A. , Vázquez-Rodríguez M. , Castaño M. , Velo A. , Alonso-Pérez F. , Gago J. , Gilcoto M. , Álvarez M. , Pardo P. C. , de la Paz M. , Ríos A. F. , Pérez F. F.
Published: May 2010

Abstract. A total of fourteen hydrographic cruises from 2000 to 2008 were conducted during the spring and autumn seasons between Spain and the Southern Ocean under the framework of the Spanish research project FICARAM. The underway measurements were processed and analysed to describe the meridional air-sea CO2 fluxes (FCO2) in the covered sector of the Atlantic Ocean. The data has been grouped into different biogeochemical oceanographic provinces based on thermohaline characteristics. The spatial and temporal distributions of FCO2 followed expected distributions and annual trends reproducing the recent climatological ΔfCO2 estimations with a mean difference of −3 ± 18 μatm (Takahashi et al., 2009). The reduction in the CO2 saturation along the meridional FICARAM cruises represented an increase of 0.02 ± 0.14 mol m−2 yr−1 in the ocean uptake of atmospheric CO2. The subtropical waters in both Hemispheres acted as a sink of atmospheric CO2 during the successive spring seasons and as a source in autumn. The coarse reduction of the ocean uptake of atmospheric CO2 observed in the North Atlantic Ocean was linked to conditions of negative phase of the North Atlantic Oscillation that prevailed during the FICARAM period. Surface waters in the North Equatorial Counter Current revealed a significant long-term decrease of sea surface salinity of −0.16 ± 0.01 yr−1 coinciding with a declination of −3.5 ± 0.9 μatm yr−1 in the air–sea disequilibrium of CO2 fugacity and a rise of oceanic CO2 uptake of −0.09 ± 0.03 mol m−2 yr−1. The largest CO2 source was located in the equatorial upwelling system. These tropical waters that reached emissions of 0.7 ± 0.5 and 1.0 ± 0.7 mol m−2 y−1 in spring and autumn, respectively, showed an interannual warming of 0.11 ± 0.03 °C yr−1 and a wind speed decrease of −0.58 ± 0.14 m s−1 yr−1 in spring cruises which suggest the weakening of upwelling events associated with warm El Niño – Southern Oscillation episodes. Contrary the surface waters of the Patagonian Sea behaved as an intense sink of CO2 in March and November. The oceanic waters of the convergence of Falkland and Brazil Currents showed the strongest CO2 absorption with a rate of −5.4 ± 3.6 mol m−2 yr−1 in November. The Southern Oceans sampled in the Drake Passage behave as an average uptake rate of −1.1 ± 0.9 mol m−2 yr−1 while the distal shelf of the Livingston Island acted as a slight source of CO2 to the atmosphere.
I-WARP: Individual Water mAin Renewal Planner
Authors: Kleiner Y. , Rajani B.
Published: May 2010

Abstract. I-WARP is based upon a nonhomogeneous Poisson approach to model breakage rates in individual water mains. The structural deterioration of water mains and their subsequent failure are affected by many factors, both static (e.g., pipe material, pipe size, age (vintage), soil type) and dynamic (e.g., climate, cathodic protection, pressure zone changes). I-WARP allows for the consideration of both static and dynamic factors in the statistical analysis of historical breakage patterns. This paper describes the mathematical approach and demonstrates its application with the help of a case study. The research project within which I-WARP was developed, was jointly funded by the National Research Council of Canada (NRC), and the Water Research foundation (formerly known as the American Water Works Association Research Foundation – AwwaRF) and supported by water utilities from USA and Canada.
Short term variations of tracer transit speed on Alpine glaciers
Authors: Werder M. A. , Schuler T. V. , Funk M.
Published: May 2010

Abstract. We present and interpret the results of a series of tracer experiments conducted on an Alpine glacier over a diurnal discharge cycle. For these injections, a moulin was used into which an ice marginal lake was draining, providing a relatively constant discharge. Measured tracer transit speeds show two diurnal maxima and minima. These findings are qualitatively different from existing observations from two series of injections at another site using a moulin fed by supraglacial meltwater with a high diurnal variability, which displayed one diurnal maximum and minimum. We use a simple two-component model of the glacier drainage system, comprising a moulin and a channel element, to simulate the measured transit speeds for all three injection series. The model successfully reproduces all the observations and shows that the same underlying processes can produce the qualitatively different behaviour depending on the different moulin input discharge regimes. Using the model, we asses the relative importance of the different measurement parameters, show that frequent measurements of moulin input discharge are indispensable and propose an experiment design to monitor the development of the drainage system over several weeks.
Diagrammatic Separation of Different Crystal Structures of A2BX4 Compounds Without Energy Minimization: A Pseudopotential Orbital Radii Approach
Authors: Zhang Xiuwen , Zunger Alex
Published: May 2010

The A2BX4 family of compounds manifest a wide range of physical properties, including transparent conductivity, ferromagnetism, and superconductivity. A 98% successful diagrammatic separation of the 44 different crystal structures of 688 oxide A2BX4 compounds (96% for 266 oxide‐only) is described by plotting the total radius of the A atom RA versus the radius of the B atom RB for many A2BX4 compounds of known structure types and seeking heuristically simple, straight boundaries in the RA versus RB plane that best separate the domains of different structure types. The radii are sums RA = Rs(A) + Rp(A) of the quantum‐mechanically calculated “orbital radii” Rs(Rp), rather than empirical radii or phenomenological electronegativity scales. These success rates using first‐principles orbital radii uniformly exceed the success rates using classic radii. Such maps afford a quick guess of the crystal structure of a yet unmade A2BX4 compound by placing its atomic orbital radii on such maps and reading off its structure type.
Solar Cells by Design: Photoelectrochemistry of TiO2 Nanorod Arrays Decorated with CdSe
Authors: Bang Jin Ho , Kamat Prashant V.
Published: May 2010

One‐dimensional (1D) nanostructures of TiO2 are grown directly on transparent, conductive glass substrate using hydrothermal/solvothermal methods. When employed as a photoanode in photoelectrochemical cells, the vertically aligned TiO2 nanorod array exhibits slower charge recombination at electrolyte interface as compared to mesoscopic TiO2 particulate film. Electrochemical deposition of CdSe onto TiO2 nanorod array is carried out to extend absorption into visible light region. The role of CdSe‐sensitized, 1D rutile TiO2 architecture in the solar cell design is discussed.
A general framework for process scheduling
Authors: Sundaramoorthy Arul , Maravelias Christos T.
Published: May 2010

Existing methods for process scheduling can be broadly classified as network‐based or sequential. The former are used to address problems where different batches of the same or different tasks are freely mixed or split, whereas the latter are used to address problems where batch mixing/splitting is not allowed. A framework is proposed that allows us to: (1) express scheduling problems in facilities that consist of network and sequential, as well as continuous subsystems, (2) formulate mixed‐integer programming (MIP) scheduling models for such problems, and (3) solve the resulting MIP formulations effectively. The proposed framework bridges the gap between network and sequential approaches, thereby addressing the major formulation challenge in the area of process scheduling, namely, the development of a framework that can be used to address a wide spectrum of problems. © 2010 American Institute of Chemical Engineers AIChE J, 57: 695–710, 2011
Metabolism of hydrogen peroxide between diapause and non‐diapause eggs of the silkworm, Bombyx Mori during chilling at 5°C
Authors: Zhao L.C. , Shi L.G.
Published: May 2010

When diapause and non‐diapause eggs of the same bivoltine strain of Bombyx mori were chilled at 5°C for more than 30 days, the hatchability of diapause eggs increased while that of non‐diapause eggs decreased, respectively. To investigate the relationship between effects of chilling on the hatchability and the metabolism of hydrogen peroxide (H2O2), content of H2O2 and activities of superoxide dismutase (SOD), xanthine oxidase (XO), and catalase (CAT) between diapause and non‐diapause eggs were determined during the chilling at 5°C. The significant enhancement of H2O2 occurred prior to the quick increase of the hatchability in diapause eggs and coincided with the quick decline of the hatchability in non‐diapause eggs, respectively. Diapause eggs contained significantly higher H2O2 and XO activity and lower CAT activity compared to non‐diapause eggs. Our results showed that there were significant differences in the metabolism of H2O2 between diapause and non‐diapause eggs during chilling and that significant enhancement of H2O2 may be involved in the diapause termination of diapause eggs and the cell damage of non‐diapause eggs. © 2010 Wiley Periodicals, Inc.
Efficient Total Synthesis of (S)‐14‐Azacamptothecin
Authors: Liu Guan‐Sai , Yao Yuan‐Shan , Xu Peng , Wang Shaozhong , Yao Zhu‐Jun
Published: May 2010

An efficient total synthesis of (S)‐14‐azacamptothecin has been accomplished in 10 steps and 56 % overall yield from 5H‐pyrano[4,3‐d]pyrimidine 8. A mild Hendrickson reagent‐triggered intramolecular cascade cyclization, a highly enantioselective dihydroxylation, and an efficient palladium‐catalyzed transformation of an O‐allyl into N‐allyl group are the key steps in the synthesis. This work provides a much higher overall yield than the previous achievement and shows sound flexibility for the further applications that will lead to new bioactive analogues.
Notch: Implications of endogenous inhibitors for therapy
Authors: Dikic Ivan , Schmidt Mirko H. H.
Published: May 2010

Soluble components of Notch signalling can be applied to manipulate a central pathway essential for the development of metazoans and often deregulated in illnesses such as stroke, cancer or cardiovascular diseases. Commonly, the Notch cascade is inhibited by small compound inhibitors, which either block the proteolysis of Notch receptors by γ‐secretases or interfere with the transcriptional activity of the Notch intracellular domain. Specific antibodies can also be used to inhibit ligand‐induced activation of Notch receptors. Alternatively, naturally occurring endogenous inhibitors of Notch signalling might offer a specific way to block receptor activation. Examples are the soluble variants of the canonical Notch ligand Jagged1 and the non‐canonical Notch ligand Dlk1, both deprived of their transmembrane regions upon ectodomain shedding, or the bona fide secreted molecule EGFL7. We present frequently used methods to decrease Notch signalling, and we discuss how soluble Notch inhibitors may be used to treat diseases.
The H19 locus: Role of an imprinted non‐coding RNA in growth and development
Authors: Gabory Anne , Jammes Hélène , Dandolo Luisa
Published: May 2010

The H19 gene produces a non‐coding RNA, which is abundantly expressed during embryonic development and down‐regulated after birth. Although this gene was discovered over 20 years ago, its function has remained unclear. Only recently a role was identified for the non‐coding RNA and/or its microRNA partner, first as a tumour suppressor gene in mice, then as a trans‐regulator of a group of co‐expressed genes belonging to the imprinted gene network that is likely to control foetal and early postnatal growth in mice. The mechanisms underlying this transcriptional or post‐transcriptional regulation remain to be discovered, perhaps by identifying the protein partners of the full‐length H19 RNA or the targets of the microRNA. This first in vivo evidence of a functional role for the H19 locus provides new insights into how genomic imprinting helps to control embryonic growth.
Windows to cell function and dysfunction: Signatures written in the boundary layers
Authors: Smith Peter J. S. , Collis Leon P. , Messerli Mark A.
Published: May 2010

The medium surrounding cells either in culture or in tissues contains a chemical mix varying with cell state. As solutes move in and out of the cytoplasmic compartment they set up characteristic signatures in the cellular boundary layers. These layers are complex physical and chemical environments the profiles of which reflect cell physiology and provide conduits for intercellular messaging. Here we review some of the most relevant characteristics of the extracellular/intercellular space. Our initial focus is primarily on cultured cells but we extend our consideration to the far more complex environment of tissues, and discuss how chemical signatures in the boundary layer can or may affect cell function. Critical to the entire essay are the methods used, or being developed, to monitor chemical profiles in the boundary layers. We review recent developments in ultramicro electrochemical sensors and tailored optical reporters suitable for the task in hand.
Spindles losing their bearings: Does disruption of orientation in stem cells predict the onset of cancer?
Authors: Graham Trevor A. , Jawad Noor , Wright Nicholas A.
Published: May 2010

Recently, Quyn et al. demonstrated that cells within the stem cell zone of human and mouse intestinal crypts tend to align their mitotic spindles perpendicular to the basal membrane of the crypt. This is associated with asymmetric division, whereby particular proteins and individual chromatids are preferentially segregated to one daughter cell. In colonic mucosa containing a heterozygous adenomatous polyposis coli gene (APC) mutation the asymmetry is lost. Here, we discuss asymmetric stem cell division as an anti‐tumourigenic mechanism. We describe how hierarchical tissue structures suppress somatic evolution, and discuss the relative merits of template strand retention to limit the accumulation of DNA replication errors. We suggest experiments to determine whether somatic mutations resulting in loss of spindle alignment confer an advantage within the stem cell niche. Finally, we discuss whether lack of spindle alignment constitutes an oncogenic event per se, with particular reference to studies in model organisms, and the timing of chromosomal instability in human cancers.
A mechanistic model of the enzymatic hydrolysis of cellulose
Authors: Levine Seth E. , Fox Jerome M. , Blanch Harvey W. , Clark Douglas S.
Published: May 2010

A detailed mechanistic model of enzymatic cellulose hydrolysis has been developed. The behavior of individual cellulase enzymes and parameters describing the cellulose surface properties are included. Results obtained for individual enzymes (T. reesei endoglucanase 2 and cellobiohydrolase I) and systems with both enzymes present are compared with experimental literature data. The model was sensitive to cellulase‐accessible surface area; the EG2–CBHI synergy observed experimentally was only predicted at a sufficiently high cellulose surface area. Enzyme crowding, which is more apparent at low surface areas, resulted in differences between predicted and experimental rates of hydrolysis. Model predictions also indicated that the observed decrease in hydrolysis rates following the initial rate of rapid hydrolysis is not solely caused by product inhibition and/or thermal deactivation. Surface heterogeneities, which are not accounted for in this work, may play a role in decreasing the hydrolysis rate. The importance of separating the enzyme adsorption and complexation steps is illustrated by the model's sensitivity to the rate of formation of enzyme–substrate complexes on the cellulose surface. Biotechnol. Bioeng. 2010;107: 37–51. © 2010 Wiley Periodicals, Inc.
Purification of cell culture‐derived modified vaccinia ankara virus by pseudo‐affinity membrane adsorbers and hydrophobic interaction chromatography
Authors: Wolff Michael W. , Siewert Corina , Hansen Sara Post , Faber Rene , Reichl Udo
Published: May 2010

A purification scheme for cell culture‐derived smallpox vaccines based on an orthogonal downstream process of pseudo‐affinity membrane adsorbers (MA) and hydrophobic interaction chromatography (HIC) was investigated. The applied pseudo‐affinity chromatography, based on reinforced sulfated cellulose and heparin‐MA, was optimized in terms of dynamic binding capacities, virus yield and process productivity. HIC was introduced as a subsequent method to further reduce the DNA content. Therefore, two screens were undertaken. First, several HIC ligands were screened for different adsorption behavior between virus particles and DNA. Second, elution from pseudo‐affinity MA and adsorption of virus particles onto the hydrophobic interaction matrix was explored by a series of buffers using different ammonium sulfate concentrations. Eventually, variations between different cultivation batches and buffer conditions were investigated.The most promising combination, a sulfated cellulose membrane adsorber with subsequent phenyl HIC resulted in overall virus particle recoveries ranging from 76% to 55% depending on the product batch and applied conditions. On average, 61% of the recovered virus particles were infective within all tested purification schemes and conditions. Final DNA content varied from 0.01% to 2.5% of the starting material and the level of contaminating protein was below 0.1%. Biotechnol. Bioeng. 2010;107: 312–320. © 2010 Wiley Periodicals, Inc.
Formation of palladium(0) nanoparticles at microbial surfaces
Authors: Bunge Michael , Søbjerg Lina S. , Rotaru Amelia‐Elena , Gauthier Delphine , Lindhardt Anders T. , Hause Gerd , Finster Kai , Kingshott Peter , Skrydstrup Troels , Meyer Rikke L.
Published: May 2010

The increasing demand and limited natural resources for industrially important platinum‐group metal (PGM) catalysts render the recovery from secondary sources such as industrial waste economically interesting. In the process of palladium (Pd) recovery, microorganisms have revealed a strong potential. Hitherto, bacteria with the property of dissimilatory metal reduction have been in focus, although the biochemical reactions linking enzymatic Pd(II) reduction and Pd(0) deposition have not yet been identified. In this study we investigated Pd(II) reduction with formate as the electron donor in the presence of Gram‐negative bacteria with no documented capacity for reducing metals for energy production: Cupriavidus necator, Pseudomonas putida, and Paracoccus denitrificans. Only large and close‐packed Pd(0) aggregates were formed in cell‐free buffer solutions. Pd(II) reduction in the presence of bacteria resulted in smaller, well‐suspended Pd(0) particles that were associated with the cells (called “bioPd(0)” in the following). Nanosize Pd(0) particles (3–30 nm) were only observed in the presence of bacteria, and particles in this size range were located in the periplasmic space. Pd(0) nanoparticles were still deposited on autoclaved cells of C. necator that had no hydrogenase activity, suggesting a hydrogenase‐independent formation mechanism. The catalytic properties of Pd(0) and bioPd(0) were determined by the amount of hydrogen released in a reaction with hypophosphite. Generally, bioPd(0) demonstrated a lower level of activity than the Pd(0) control, possibly due to the inaccessibility of the Pd(0) fraction embedded in the cell envelope. Our results demonstrate the suitability of bacterial cells for the recovery of Pd(0), and formation and immobilization of Pd(0) nanoparticles inside the cell envelope. However, procedures to make periplasmic Pd(0) catalytically accessible need to be developed for future nanobiotechnological applications. Biotechnol. Bioeng. 2010;107: 206–215. © 2010 Wiley Periodicals, Inc.
Associations between leptin and adiponectin receptor upregulation, visceral obesity and tumour stage in oesophageal and junctional adenocarcinoma
Authors: Howard J M , Beddy P , Ennis D , Keogan M , Pidgeon G P , Reynolds J V
Published: May 2010

Background

Obesity is associated with oesophageal adenocarcinoma, but mechanisms linking fat and carcinogenesis remain poorly understood. Altered circulating adipocytokines may be important. This study aimed to identify pathways through which visceral fat impacts on tumour biology.

Methods

Seventy-five patients with oesophageal adenocarcinoma underwent anthropometric and radiological assessment of obesity. Expression of leptin receptor (ObR) and adiponectin receptors 1 and 2 (AdipR1, AdipR2) was quantified by real-time reverse transcriptase–polymerase chain reaction. The human oesophageal adenocarcinoma cell line OE33 was used as the calibrator sample.

Results

Ninety-one per cent of tumours expressed ObR, 95 per cent expressed AdipR1 and 100 per cent expressed AdipR2. Relative expression of ObR was upregulated in 67 per cent, and AdipR1 and AdipR2 were downregulated in 55 and 68 per cent respectively, relative to the calibrator sample. Upregulated ObR and AdipR2 expression was significantly associated with anthropometric and radiological measures of obesity. Upregulated ObR was associated with advanced tumour and node category (P = 0·036 and P = 0·025 respectively), and upregulated AdipR2 with nodal involvement (P = 0·037).

Conclusion

Obesity is associated with upregulated ObR and AdipR2 expression in oesophageal adenocarcinoma. The association of ObR and AdipR2 with tumour stage suggest that pathways involving adipocytokines affect tumour biology.
Cost-effectiveness analysis of general anaesthesia versus local anaesthesia for carotid surgery (GALA Trial)
Authors:   GALA Collaborative Group, Gomes M , Soares M O , Dumville J C , Lewis S C , Torgerson D J , Bodenham A R , Gough M J , Warlow C P
Published: May 2010

Background

Health outcomes and costs are both important when deciding whether general (GA) or local (LA) anaesthesia should be used during carotid endarterectomy. The aim of this study was to assess the cost-effectiveness of carotid endarterectomy under LA or GA in patients with symptomatic or asymptomatic carotid stenosis for whom surgery was advised.

Methods

Using patient-level data from a large, multinational, randomized controlled trial (GALA Trial) time free from stroke, myocardial infarction or death, and costs incurred were evaluated. The cost-effectiveness outcome was incremental cost per day free from an event, within a time horizon of 30 days.

Results

A patient undergoing carotid endarterectomy under LA incurred fewer costs (mean difference £178) and had a slightly longer event-free survival (difference 0·16 days, but the 95 per cent confidence limits around this estimate were wide) compared with a patient who had GA. Existing uncertainty did not have a significant impact on the decision to adopt LA, over a wide range of willingness-to-pay values.

Conclusion

If cost-effectiveness was considered in the decision to adopt GA or LA for carotid endarterectomy, given the evidence provided by this study, LA is likely to be the favoured treatment for patients for whom either anaesthetic approach is clinically appropriate.
Stakeholder management and sustainability strategies in the French nuclear industry
Authors: Banerjee Subhabrata Bobby , Bonnefous Annabel‐Mauve
Published: May 2010

This paper describes how a nuclear power corporation integrates sustainability into corporate strategies and practices. The case study focuses on one of the world's largest nuclear power generators and describes the corporate capture of sustainable development in its strategic efforts to promote a growth strategy. The paper shows how corporate strategies to address sustainability concerns involve managing different stakeholders, enabling the corporation to sustain its economic growth strategy. Three types of stakeholder management strategy are identified: reinforcement strategies for supportive stakeholders, containment strategies for obstructive stakeholders and stabilization strategies for passive stakeholders. The paper argues that, despite claims of sustainable development in the nuclear industry, there is no significant shift in the ‘business as usual’ approach and that sustainable development is merely reframed as sustainable growth. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Cyanide‐Bridged [CoII2MII] and [CoII2MII2] Complexes Based on the [CoII(triphos)(CN)2] Building Block: Syntheses, Structures, Magnetic Properties, and Density Functional Theoretical Studies
Authors: Karadas Ferdi , Shatruk Michael , Perez Lisa M. , Dunbar Kim R.
Published: May 2010

Two families of cationic cyanide‐bridged complexes, namely, {[Co(triphos)(CN)2]2[M(MeOH)4]}(ClO4)2 ([Co2M] M=Mn, Fe, Co, and Ni; triphos=1,1,1‐tris((diphenylphosphino)methyl)ethane) and {[Co(triphos)(CN)2]2[M(MeOH)4]2}(ClO4)4 ([Co2M2] M=Mn and Ni) have been prepared from reactions of [CoII(triphos)(CN)2] and M(ClO4)2⋅6H2O (M=Mn, Fe, Co, Ni) in methanol. The trinuclear complexes [Co2Mn], [Co2Fe], and [Co2Co], as well as both new tetranuclear complexes [Co2Mn2] and [Co2Ni2], exhibit antiferromagnetic coupling between metal centers. In contrast, the [Co2Ni] is characterized by ferromagnetic interactions between the CoII and NiII centers. The magnetic behavior for these complexes was investigated by DFT calculations and was found to derive from overlap patterns of the different magnetic orbitals as influenced by the angles of the cyanide bridges.
Enantioselective Organocatalytic Addition of Azlactones to Maleimides: A Highly Stereocontrolled Entry to 2,2‐Disubstituted‐2H‐oxazol‐5‐ones
Authors: Alba Andrea‐Nekane R. , Valero Guillem , Calbet Teresa , Font‐Bardía Mercé , Moyano Albert , Rios Ramon
Published: May 2010

The first highly diastereo‐ and enantioselective organocatalytic synthesis of 2,2‐disubstituted‐2H‐oxazol‐5‐ones is described. The addition of oxazolones to maleimides is promoted by bifunctional thiourea catalysts, which afford the corresponding 2,2‐disubstituted‐2H‐oxazol‐5‐ones with total regio‐ and stereocontrol.
Luminescent Ionic Liquid Crystals from Self‐Assembled BODIPY Disulfonate and Imidazolium Frameworks
Authors: Olivier Jean‐Hubert , Camerel Franck , Ulrich Gilles , Barberá Joaquín , Ziessel Raymond
Published: May 2010

A series of modular mesogenic salts based on the combination of anionic 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (F‐BODIPY) 2,6‐disulfonate dyes and trialkoxybenzyl‐functionalised imidazolium cations has been designed and synthesised. Each salt contains a rigid dianionic BODIPY core associated with two imidazolium cations functionalised by 1,2,3‐trialkoxybenzyl (alkyl=n‐C8, n‐C12 or n‐C16) units or, in one case, with imidazolium cations functionalised by a trialkylgallate (3,4,5‐trialkoxybenzoate) unit in which the 3,5‐dialkyl groups are terminated with a polymerisable acrylate entity. All these compounds were highly fluorescent in solution with quantum yields ranging from 54 to 62 %. In the solid state, the width of the emission band observed at around 650 nm is a clear signature of aggregation. With the trialkoxybenzylimidazolium cations, polarised optical microscopy (POM) and X‐ray scattering experiments showed that columnar mesophases were formed. Differential scanning calorimetry (DSC) studies confirmed the mesomorphic behaviour from room temperature to about 130 °C for salts with alkyl chains containing 8, 12 and 16 carbon atoms. The strong luminescence of the BODIPY unit was maintained in the mesophase and fluorescence measurements confirmed the presence of J aggregates in all cases. The salt containing the gallate‐functionalised imidazolium cations showed no mesomorphism but the acrylate terminal units could be used to engender photoinitiated polymerisation thereby allowing the material to be immobilised on glass plates. The polymerisation process was followed by FTIR spectroscopy and the fixed and patterned films were highly fluorescent with a solid‐state emission close to that of the complex in the solid state.
Activity and Enantioselectivity of the Hydroxynitrile Lyase MeHNL in Dry Organic Solvents
Authors: Paravidino Monica , Sorgedrager Menno J. , Orru Romano V. A. , Hanefeld Ulf
Published: May 2010

Water concentration affects both the enantioselectivity and activity of enzymes in dry organic media. Its influence has been investigated using the hydrocyanation of benzaldehyde catalyzed by hydroxynitrile lyase cross‐linked enzyme aggregate (MeHNL‐CLEA) as a model reaction. The enzyme displayed higher enantioselectivity at higher water concentration, thus suggesting a positive effect of enzyme flexibility on selectivity. The activity increased on reducing the solvent water content, but drastic dehydration of the enzyme resulted in a reversible loss of activity.
Syntheses and Antibacterial Properties of iso‐Platencin, Cl‐iso‐Platencin and Cl‐Platencin: Identification of a New Lead Structure
Authors: Tiefenbacher Konrad , Gollner Andreas , Mulzer Johann
Published: May 2010

Platencin is a novel antibiotic which is active against multiresistant pathogens. We describe efficient syntheses of three platencin analogues of varying activities which allow further conclusions about the pharmacophoric part of the molecule. The unnatural antibiotic iso‐platencin, which is about as active as natural platencin, but much more selective, was identified as a new lead structure.
(Et4N)4 [V4O12]×2H2O.
Authors: Nakano Hroyuki , Ozeki Tomoji , Yagasaki Atsushi
Published: May 2010

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Electrochemical Characteristics of Li0.7[Ni1/6Mn5/6]O2 Cathode Materials.
Authors: Park K. S. , Park S. H. , Sun Y.‐K. , Nahm K. S. , Yoon C. S. , Kim C. K. , Lee Yun Sung , Yoshio Masaki
Published: May 2010

For Abstract see ChemInform Abstract in Full Text.
The Two Antiferromagnetic Phases of TbPtGe2.
Authors: Papathanassiou G. F. , Kotsanidis P. A. , Yakinthos J. K. , Schaefer W.
Published: May 2010

For Abstract see ChemInform Abstract in Full Text.
Giant Barrier Layer Capacitance Effects in CaCu3Ti4O12 Ceramics.
Authors: Adams Timothy B. , Sinclair Derek C. , West Anthony R.
Published: May 2010

For Abstract see ChemInform Abstract in Full Text.
Phase Diagram of the AgGaSe2—CdSe System and Crystal Structure of the AgCd2GaSe4 Compound.
Authors: Olekseyuk I. D. , Gulay L. D. , Parasyuk O. V. , Husak O. A. , Kadykalo E. M.
Published: May 2010

For Abstract see ChemInform Abstract in Full Text.
Autocatalytic Oxidation of Lead Crystallite Surfaces.
Authors: Thuermer Konrad , Williams Ellen , Reutt‐Robey Janice
Published: May 2010

For Abstract see ChemInform Abstract in Full Text.
Synthesis of Europium Oxide Nanorods by Ultrasound Irradiation.
Authors: Pol V. G. , Palchik O. , Gedanken A. , Felner I.
Published: May 2010

For Abstract see ChemInform Abstract in Full Text.
(DEA‐H)7+In11S21H2: A New Layered Open Framework Indium Sulfide Based on the Interconnection of [In10S20]10‐ Supertetrahedra.
Authors: Pitzschke Dragan , Naether Christian , Bensch Wolfgang
Published: May 2010

For Abstract see ChemInform Abstract in Full Text.