bluuebunny/crossref_metadata_2025 huggingface dataset:
Charge induced stability of water droplets in subsaturated environment
Authors: Nielsen J. K. , Maus C. , Rzesanke D. , Leisner T.
Published: March 2011

Abstract. Atmospheric liquid and solid water particles are stabilized if they are coated with either negative or positive electric charge. The surface charge causes an increase of the partial pressure of water vapour close to the surface of each particle, effectively allowing the particles to remain in their condensed phase even if the environmental relative humidity drops below unity. The theory, briefly presented in this paper, predicts a zero parameter relation between surface charge density and water vapour pressure. This relation was tested in a series of Electrodynamic Balance experiments. The measurements were performed by stabilizing charged droplets of pure water near an ice-surface. We observed a divergence in radius as the temperature approached the freezing point from below. We find that the measurements confirm the theory within the experimental uncertainty. In some cases this generally overlooked effect may have impact on cloud processes and on results produced by Electrodynamic Balance experiments.
Primary sources of PM2.5 organic aerosol in an industrial Mediterranean city, Marseille
Authors: El Haddad I. , Marchand N. , Wortham H. , Piot C. , Besombes J.-L. , Cozic J. , Chauvel C. , Armengaud A. , Robin D. , Jaffrezo J.-L.
Published: March 2011

Abstract. Marseille, the most important port of the Mediterranean Sea, represents a challenging case study for source apportionment exercises, combining an active photochemistry and multiple emission sources, including fugitive emissions from industrial sources and shipping. This paper presents a Chemical Mass Balance (CMB) approach based on organic markers and metals to apportion the primary sources of organic aerosol in Marseille, with a special focus on industrial emissions. Overall, the CMB model accounts for the major primary anthropogenic sources including motor vehicles, biomass burning and the aggregate emissions from three industrial processes (heavy fuel oil combustion/shipping, coke production and steel manufacturing) as well as some primary biogenic emissions. This source apportionment exercise is well corroborated by 14C measurements. Primary OC estimated by the CMB accounts on average for 22% of total OC and is dominated by the vehicular emissions that contribute on average for 17% of OC mass concentration (vehicular PM contributes for 17% of PM2.5). Even though industrial emissions contribute only 2.3% of the total OC (7% of PM2.5), they are associated with ultrafine particles (Dp<80 nm) and high concentrations of Polycyclic Aromatic Hydrocarbons (PAH) and heavy metals such as Pb, Ni and V. On one hand, given that industrial emissions governed key primary markers, their omission would lead to substantial uncertainties in the CMB analysis performed in areas heavily impacted by such sources, hindering accurate estimation of non-industrial primary sources and secondary sources. On the other hand, being associated with bursts of submicron particles and carcinogenic and mutagenic components such as PAH, these emissions are most likely related with acute ill-health outcomes and should be regulated despite their small contributions to OC. Another important result is the fact that 78% of OC mass cannot be attributed to the major primary sources and, thus, remains un-apportioned. We have consequently critically investigated the uncertainties underlying our CMB apportionments. While we have provided some evidence for photochemical decay of hopanes, this decay does not appear to significantly alter the CMB estimates of the total primary OC. Sampling artifacts and unaccounted primary sources also appear to marginally influence the amount of un-apportioned OC. Therefore, this significant amount of un-apportioned OC is mostly attributed to secondary organic carbon that appears to be the major component of OC during the whole period of study.
Insights into the secondary fraction of the organic aerosol in a Mediterranean urban area: Marseille
Authors: El Haddad I. , Marchand N. , Temime-Roussel B. , Wortham H. , Piot C. , Besombes J.-L. , Baduel C. , Voisin D. , Armengaud A. , Jaffrezo J.-L.
Published: March 2011

Abstract. A comprehensive aerosol characterization was conducted at Marseille during summer, including organic (OC) and elemental carbon (EC), major ionic species, radiocarbon (14C), water-soluble OC and HULIS (HUmic LIke Substances), elemental composition and primary and secondary organic markers. This paper is the second paper of a two-part series that uses this dataset to investigate the sources of Organic Aerosol (OA). While the first paper investigates the primary sources (El Haddad et al., 2010), this second paper focuses on the secondary fraction of the organic aerosol. In the context of overall OC mass balance, primary OC (POC) contributes on average for only 22% and was dominated by vehicular emissions accounting on average for 17% of OC. As a result, 78% of OC mass cannot be attributed to the major primary sources and remains un-apportioned. Radiocarbon measurements suggest that more than 70% of this fraction is of non-fossil origin, assigned predominantly to biogenic secondary organic carbon (BSOC). Therefore, contributions from three traditional BSOC precursors, isoprene, α-pinene and β-caryophyllene, were considered. These were estimated using the ambient concentrations of Secondary Organic Aerosol (SOA) markers from each precursor and laboratory-derived marker mass fraction factors. Secondary organic markers derived from isoprene photo-oxidation (ie: 2-methylglyceric acid and 2-methyltetrols) do not exhibit the same temporal trends. This variability was assigned to the influence of NOx concentration on their formation pathways and to their potential decay by further processing in the atmosphere. The influence of changes in isoprene chemistry on assessment of isoprene SOC contribution was evaluated explicitly. The results suggest a 60-fold variation between the different estimates computed using different isoprene SOC markers, implying that the available profiles do not reflect the actual isoprene SOC composition observed in Marseille. Using the marker-based approach, the aggregate contribution from traditional BSOC was estimated at only 4.2% of total OC and was dominated by α-pinene SOC accounting on average for 3.4% of OC. As a result, these estimates underpredict the inexplicably high loadings of OC. This underestimation can be associated with (1) uncertainties underlying the marker-based approach, (2) presence of other SOC precursors and (3) further processing of fresh SOC, as indicated by organosulfates (RSO4H) and HUmic LIke Substances (HULIS) measurements.
Branch-level measurement of total OH reactivity for constraining unknown BVOC emission during the CABINEX (Community Atmosphere-Biosphere INteractions Experiments)-09 Field Campaign
Authors: Kim S. , Guenther A. , Karl T. , Greenberg J.
Published: March 2011

Abstract. We present OH reactivity measurements using the comparative reactivity method with a branch enclosure technique for four different tree species (red oak, white pine, beech and red maple) in the UMBS PROPHET tower footprint during the Community Atmosphere Biosphere INteraction EXperiment (CABINEX) field campaign in July of 2009. Proton Transfer Reaction-Mass Spectrometry (PTR-MS) was sequentially used as a detector for OH reactivity and BVOC including isoprene and monoterpenes (MT), in enclosure air, so that the measurement dataset contains both measured OH reactivity and calculated OH reactivity from well-known BVOC. The results indicate that isoprene and MT, and in one case a sesquiterpene, can account for the measured OH reactivity. Significant discrepancy between measured OH reactivity and calculated OH reactivity from isoprene and MT is found for the red maple enclosure dataset but it can be reconciled by adding reactivity from emission of a sesquiterpene, α-farnesene, detected by GC-MS. This leads us to conclude that no significant unknown BVOC emission contributed to ambient OH reactivity from these trees at least during the study period. This conclusion leads us to explore the contribution from unmeasured isoprene (the dominant OH sink in this ecosystem) oxidation products such as hydroxyacetone, glyoxal, methylglyoxal and C4 and C5-hydroxycarbonyl using recently published isoprene oxidation mechanisms (Mainz Isoprene Mechanism II and Leuven Isoprene Mechanism). Evaluation of conventionally unmeasured first generation oxidation products of isoprene and their possible contribution to ambient missing OH reactivity indicates that the ratio of OH reactivity from unmeasured products over OH reactivity from MVK + MACR is strongly dependent on NO concentrations. The unmeasured oxidation products can contribute ~7.2% (8.8% from LIM and 5.6% by MIM 2 when NO = 100 pptv) of the isoprene contribution towards total ambient OH reactivity. This amount can explain ~8.0% (9.7% from LIM and 6.2% from MIM 2) of missing OH reactivity, reported by Di Carlo et al. (2004) at the same site. Further study on contribution from further generation of unmeasured oxidation products should be followed to constrain tropospheric photochemical reactivity of BVOC that have important implications for both photochemical ozone and secondary organic aerosol formation.
Refractivity and temperature climate records from multiple radio occultation satellites consistent within 0.05%
Authors: Foelsche U. , Scherllin-Pirscher B. , Ladstädter F. , Steiner A. K. , Kirchengast G.
Published: March 2011

Abstract. Data consistency is an important prerequisite to build radio occultation (RO) climatologies based on a combined record of data from different satellites. The presence of multiple RO receiving satellites in orbit over the same time period allows for testing this consistency. We used RO data from CHAMP (CHAllenging Minisatellite Payload for geoscientific research), six FORMOSAT-3/COSMIC satellites (Formosa Satellite Mission 3/Constellation Observing System for Meteorology, Ionosphere and Climate, F3C), and GRACE-A (Gravity Recovery and Climate Experiment). We show latitude-altitude-resolved results for an example month (October 2007) and the temporal evolution of differences in a climate record of global and monthly means from January 2007 to December 2009. Latitude- and altitude-resolved refractivity and dry temperature climatologies clearly show the influence of different sampling characteristics; monthly mean deviations from the multi-satellite mean over the altitude domain 10 km to 30 km typically reach 0.1% and 0.2 K, respectively. Nevertheless, the 3-year average deviations (shorter for CHAMP) are less than 0.03% and 0.05 K, respectively. We find no indications for instrument degradation, instationarities in the RO records, or temporal trends in sampling patterns. Based on analysis fields from ECMWF (European Centre for Medium-Range Weather Forecasts), we can estimate – and subtract – the sampling error from each monthly climatology. After such subtraction, refractivity deviations are found reduced to <0.05% in almost any month and dry temperature deviations to <0.05 K (<0.02% relative) for almost every satellite and month. 3-year average deviations are even reduced to <0.01% and <0.01 K (CHAMP: −0.05 K), respectively, establishing an amazing consistency of RO climatologies from different satellites. If applying the same processing scheme for all data, refractivity and dry temperature records from individual satellites with similar bending angle noise can be safely combined up to 30 km altitude (refractivity also up to 35 km) to a consistent single climate record of substantial value for climate monitoring in the upper troposphere and lower stratosphere.
Experimental nitrogen, phosphorus, and potassium deposition decreases summer soil temperatures, water contents, and soil CO2 concentrations in a northern bog
Authors: Wendel S. , Moore T. , Bubier J. , Blodau C.
Published: March 2011

Abstract. Ombrotrophic peatlands depend on airborne nitrogen (N), whose deposition has increased in the past and lead to disappearance of mosses and increased shrub biomass in fertilization experiments. The response of soil water content, temperature, and carbon gas concentrations to increased nutrient loading is poorly known and we thus determined these data at the long-term N fertilization site Mer Bleue bog, Ontario, during a two month period in summer. Soil temperatures decreased with NPK addition in shallow peat soil primarily during the daytime (t-test, p < 0.05) owing to increased shading, whereas they increased in deeper peat soil (t-test, p < 0.05), probably by enhanced thermal conductivity. These effects were confirmed by RMANOVA, which also suggested an influence of volumetric water contents as co-variable on soil temperature and vice versa (p < 0.05). Averaged over all fertilized treatments, the mean soil temperatures at 5 cm depth decreased by 1.3 °C and by 4.7 °C (standard deviation 0.9 °C) at noon. Water content was most strongly affected by within-plot spatial heterogeneity but also responded to both N and PK load according to RMANOVA (p < 0.05). Overall, water content and CO2 concentrations in the near-surface peat (t-test, p < 0.05) were lower with increasing N load, suggesting more rapid soil gas exchange. The results thus suggest that changes in bog ecosystem structure with N deposition have significant ramifications for physical parameters that in turn control biogeochemical processes.
Global spatial distribution of natural riverine silica inputs to the coastal zone
Authors: Dürr H. H. , Meybeck M. , Hartmann J. , Laruelle G. G. , Roubeix V.
Published: March 2011

Abstract. Silica, SiO2, in dissolved (DSi) and particulate (PSi) form, is both a major product of continental weathering as well as an essential nutrient in terrestrial and aquatic systems. Here we present estimates of the spatial distribution of riverine silica fluxes under natural conditions, i.e. without human influence, to ~140 segments of the global coastal zone. Focussing on the construction of the DSi budget, natural DSi concentration is multiplied with discharge of rivers for each segment for documented basins and segments. Segments with no documentation available are estimated using clustered information based mainly on considerations of local lithology, climate, and lake retention. We approximate fluxes of particulate silica in various forms (PSi) from fluxes of suspended matter, calculated from existing models. Results have been established for silica fluxes, concentrations and yields for drainage basins of the different continents, oceans basins as well as coastal segment basins. For the continental surfaces actually draining into the oceans (exorheic regions, representing 114.7 million (M) km2), 371 M t y−1 of DSi and 8835 M t y−1 of PSi are transported, corresponding to a mean concentration of 9.5 mg l−1 and 226 mg l−1, and to a mean yield of 3.3 t km−2 y−1 and 77 t km−2 y−1, respectively. DSi yields exceeding 6.6 t km−2 y−1, i.e. >2× the global average, represent 17.4% of the global continental ice-free exorheic area but correspond to 56.0% of DSi fluxes. Pacific catchments hold most of the hyper-active areas (>5× global average), suggesting a close connection between tectonic activity and DSi fluxes resulting from silicate weathering. The macro-filters of regional and marginal seas intercept 33% and 46% of the total dissolved and particulate silica fluxes. The mass of DSi received from rivers per unit square area of various oceans ranges over more than one order of magnitude. When expressed per unit volume and when individual regional seas are considered this figure ranges over two to three orders of magnitude, an illustration of the heterogeneity of the land to sea connection.
Hydrological processes affecting the subtropical NE Atlantic (34–38° N) over the last 30 ka: evidence from phyto- and zooplankton assemblages
Authors: Penaud A. , Eynaud F. , Voelker A. , Marret F. , Turon J. L. , Rossignol L. , Blamart D. , Mulder T.
Published: March 2011

Abstract. New dinocyst analyses were conducted on core MD99-2339 retrieved from the central Gulf of Cadiz. Dinocyst and foraminiferal assemblages from this core are combined with existing data off SW Portugal and NW Morocco to investigate past hydrological and primary productivity regimes in the subtropical NE Atlantic Ocean over the last 30 ka. Our results have revealed highest upwelling intensity during Heinrich Stadial 1 (HS 1) and the Younger Dryas and weaker upwelling cells during the Last Glacial Maximum and HS 2, off the SW Iberian and NW Moroccan margins. Similar assemblages between Cadiz and Morocco and distinct species off Portugal were observed during the cold climatic extremes that punctuated the last 30 ka. This pattern has been linked to the occurrence of a hydrological structure between SW Iberia and Cadiz during the last glacial period, probably similar to the modern Azores Front. This front was probably responsible locally for heterotrophic dinocysts found in the Gulf of Cadiz during the last glacial period, even if this sector is not conductive to upwelling phenomena by Ekman transport. Regional reconstructions of paleo-sea-surface temperatures using dinocyst and foraminiferal transfer functions, as well as alkenones, are also discussed and depict coherent scenarios over the last 30 ka. However, some mismatches are observed between the different quantitative reconstructions such as during HS 1 in the Gulf of Cadiz and during the LGM at the three core locations.
Effect of ocean acidification on otolith development in larvae of a tropical marine fish
Authors: Munday P. L. , Hernaman V. , Dixson D. L. , Thorrold S. R.
Published: March 2011

Abstract. Calcification in many invertebrate species is predicted to decline due to ocean acidification. The potential effects of elevated pCO2 and reduced carbonate saturation state on other species, such as fish, are less well understood. Fish otoliths (earbones) are composed of aragonite, and thus, might be susceptible to either the reduced availability of carbonate ions in seawater at low pH, or to changes in extracellular concentrations of bicarbonate and carbonate ions caused by acid-base regulation in fish exposed to high pCO2. We reared larvae of the clownfish Amphiprion percula from hatching to settlement at three pHNBS and pCO2 levels (control: pH 8.15 and 404 μatm CO2; intermediate: pH 7.8 and 1050 μatm CO2; extreme: pH 7.6 and 1721 μatm CO2) to test the possible effects of ocean acidification on otolith development. There was no effect of the intermediate treatment (pH 7.8 and 1050 μatm CO2) on otolith size, shape, symmetry between left and right otoliths, or otolith elemental chemistry, compared with controls. However, in the more extreme treatment (pH 7.6 and 1721 μatm CO2) otolith area and maximum length were larger than controls, although no other traits were affected. Our results support the hypothesis that pH regulation in the otolith endolymph of fish exposed to elevated pCO2 can lead to increased precipitation of CaCO3 in otoliths of larval fish, as proposed by an earlier study, however, our results also show that sensitivity varies considerably among species. Importantly, our results suggest that otolith development in clownfishes is robust to even the more pessimistic changes in ocean chemistry predicted to occur by 2100.
Origin and fate of the secondary nitrite maximum in the Arabian Sea
Authors: Lam P. , Jensen M. M. , Kock A. , Lettmann K. A. , Plancherel Y. , Lavik G. , Bange H. W. , Kuypers M. M. M.
Published: March 2011

Abstract. The Arabian Sea harbours one of the three major oxygen minimum zones (OMZs) in the world's oceans, and it alone is estimated to account for ~10–20% of global oceanic nitrogen (N) loss. While actual rate measurements have been few, the consistently high accumulation of nitrite (NO2−) coinciding with suboxic conditions in the central-northeastern part of the Arabian Sea has led to the general belief that this is the region where active N-loss takes place. Most subsequent field studies on N-loss have thus been drawn almost exclusively to the central-NE. However, a recent study measured only low to undetectable N-loss activities in this region, compared to orders of magnitude higher rates measured towards the Omani shelf where little NO2− accumulated (Jensen et al., 2011). In this paper, we further explore this discrepancy by comparing the NO2− producing and consuming processes, and examining the relationship between the overall NO2− balance and active N-loss in the Arabian Sea. Based on a combination of 15N-incubation experiments, functional gene expression analyses, nutrient profiling and flux modeling, our results showed that NO2− accumulated in the Central-NE Arabian Sea due to a net production via primarily active nitrate (NO3−) reduction and to a certain extent ammonia oxidation. Meanwhile, NO2− consumption via anammox, denitrification and dissimilatory nitrate/nitrite reduction to ammonium (NH4+) were hardly detectable in this region, though some loss to NO2− oxidation was predicted from modeled NO3− changes. No significant correlation was found between NO2− and N-loss rates (p>0.05). This discrepancy between NO2− accumulation and lack of active N-loss in the Central-NE Arabian Sea is best explained by the deficiency of organic matter that is directly needed for further NO2− reduction to N2O, N2 and NH4+, and indirectly for the remineralized NH4+ required by anammox. Altogether, our data do not support the long-held view that NO2− accumulation is a direct activity indicator of N-loss in the Arabian Sea or other OMZs. Instead, NO2− accumulation more likely corresponds to long-term integrated N-loss that has passed the prime of high and/or consistent in situ activities.
Climate change, in the framework of the constructal law
Authors: Clausse M. , Meunier F. , Reis A. H. , Bejan A.
Published: March 2011

Abstract. Here we present a simple and transparent alternative to the complex models of Earth thermal behavior under time-changing conditions. We show the one-to-one relationship between changes in atmospheric properties and time-dependent changes in temperature and its distribution on Earth. The model accounts for convection and radiation, thermal inertia and changes in albedo (ρ) and greenhouse factor (γ). The constructal law is used as the principle that governs the evolution of flow configuration in time, and provides closure for the equations that describe the model. In the first part of the paper, the predictions are tested against the current thermal state of Earth. Next, the model showed that for two time-dependent scenarios, (δρ = 0.002; δγ = 0.011) and (δρ = 0.002; δγ = 0.005) the predicted equatorial and polar temperature increases and the time scales are (ΔTH = 1.16 K; ΔTL = 1.11 K; 104 years) and (0.41 K; 0.41 K; 57 years), respectively. In the second part, a continuous model of temperature variation was used to predict the thermal response of the Earth's surface for changes bounded by δρ = δγ and δρ = −δγ. The results show that the global warming amplitudes and time scales are consistent with those obtained for δρ = 0.002 and δγ = 0.005. The poleward heat current reaches its maximum in the vicinity of 35° latitude, accounting for the position of the Ferrel cell between the Hadley and Polar Cells.
Quantifying the impact of groundwater depth on evapotranspiration in a semi-arid grassland region
Authors: Soylu M. E. , Istanbulluoglu E. , Lenters J. D. , Wang T.
Published: March 2011

Abstract. Interactions between shallow groundwater and land surface processes play an important role in the ecohydrology of riparian zones. Some recent land surface models (LSMs) incorporate groundwater-land surface interactions using parameterizations at varying levels of detail. In this paper, we examine the sensitivity of land surface evapotranspiration (ET) to water table depth, soil texture, and two commonly used soil hydraulic parameter datasets using four models with varying levels of complexity. The selected models are Hydrus-1D, which solves the pressure-based Richards equation, the Integrated Biosphere Simulator (IBIS), which simulates interactions among multiple soil layers using a (water-content) variant of the Richards equation, and two forms of a steady-state capillary flux model coupled with a single-bucket soil moisture model. These models are first evaluated using field observations of climate, soil moisture, and groundwater levels at a semi-arid site in south-central Nebraska, USA. All four models are found to compare reasonably well with observations, particularly when the effects of groundwater are included. We then examine the sensitivity of modelled ET to water table depth for various model formulations, node spacings, and soil textures (using soil hydraulic parameter values from two different sources, namely Rawls and Clapp-Hornberger). The results indicate a strong influence of soil texture and water table depth on groundwater contributions to ET. Furthermore, differences in texture-specific, class-averaged soil parameters obtained from the two literature sources lead to large differences in the simulated depth and thickness of the "critical zone" (i.e., the zone within which variations in water table depth strongly impact surface ET). Depending on the depth-to-groundwater, this can also lead to large discrepancies in simulated ET (in some cases by more than a factor of two). When the Clapp-Hornberger soil parameter dataset is used, the critical zone becomes significantly deeper, and surface ET rates become much higher, resulting in a stronger influence of deep groundwater on the land surface energy and water balance. In general, we find that the simulated sensitivity of ET to the choice of soil hydraulic parameter dataset is greater than the sensitivity to soil texture defined within each dataset, or even to the choice of model formulation. Thus, our findings underscore the need for future modelling and field-based studies to improve the predictability of groundwater-land surface interactions in numerical models, particularly as it relates to the parameterization of soil hydraulic properties.
The seasonal cycle and interannual variability of surface energy balance and melt in the ablation zone of the west Greenland ice sheet
Authors: van den Broeke M. , van de Wal R. , Smeets P.
Published: March 2011

Abstract. We present the seasonal cycle and interannual variability of the surface energy balance (SEB) in the ablation zone of the west Greenland ice sheet, using seven years (September 2003–August 2010) of hourly observations from three automatic weather stations (AWS). The AWS are situated along the 67° N latitude circle at elevations of 490 m a.s.l. (S5), 1020 m a.s.l. (S6) and 1520 m a.s.l. (S9) at distances of 6, 38 and 88 km from the ice sheet margin. The hourly AWS data are fed into a model that calculates all SEB components and melt rate; the model allows for shortwave radiation penetration in ice and time-varying surface momentum roughness. Snow depth is prescribed from albedo and sonic height ranger observations. Modelled and observed surface temperatures for non-melting conditions agree very well, with RMSE's of 0.97–1.26 K. Modelled and observed ice melt rates at the two lowest sites also show very good agreement, both for total cumulative and 10-day cumulated amounts. Melt frequencies and melt rates at the AWS sites are discussed. Although absorbed shortwave radiation is the most important energy source for melt at all three sites, interannual melt variability at the lowest site is driven mainly by variability in the turbulent flux of sensible heat. This is explained by the quasi-constant summer albedo in the lower ablation zone, limiting the influence of the melt-albedo feedback, and the proximity of the snow free tundra, which heats up considerably in summer.
Incontinentia Pigmenti and Bipolar Aphthosis: An Unusual Combination
Authors: Márquez Balbás G. , González-Enseñat M. A. , Vicente A. , Creus-Vila L. , Antón J. , Umbert-Millet P.
Published: March 2011

Incontinentia pigmenti (IP) is an uncommon X-linked dominant multisystem disorder, lethal in the majority of affected males in utero and variably expressed in females. The cutaneous manifestations are diagnostic and classically occur in four stages: vesicular, verrucous, hyperpigmented, and atrophic. The skin lesions are typically spread along the lines of Blaschko, and they are usually present at birth. It may be variably accompanied by dental, ocular, neurologic, bones and joints, and development anomalies. The genes IP has been mapped to Xq28. Mutations in the NEMO/IKKγgene, located at Xq28, have been found to cause expression of the disease. Behçets disease is a multisystem disorder consisting of recurrent oral aphtae, genital ulcers, pustular skin eruption, and uveitis. Occasionally there are other articular, neurological, intestinal, or vascular abnormalities. This disease is rare in children. Here, we report a case of a 16-year-old female with the rare combination of incontinentia pigmenti and an aphthosis bipolar, and we discuss the probably relationship between these two diseases.
Porous Poly(ε‐caprolactone) Nerve Guide Filled with Porous Gelatin Matrix for Nerve Tissue Engineering
Authors: Tonda‐Turo Chiara , Audisio Chiara , Gnavi Sara , Chiono Valeria , Gentile Piergiorgio , Raimondo Stefania , Geuna Stefano , Perroteau Isabelle , Ciardelli Gianluca
Published: March 2011

The preparation and characterization of PCL guides filled with a porous matrix of a freeze‐dried, genipin‐crosslinked gelatin sponge (GL/GP) is described. Porous guides are obtained by dip coating a rotating mandrel with a PCL/PEO blend solution followed by PEO solvent extraction. PCL/PEO 60/40 is selected as the optimal composition to obtain model porous membranes with suitable morphological properties to ensure nutrient permeation and moderate stiffness. GL/GP sponges show increased mechanical strength and water stability, compared to uncrosslinked GL sponges. GL/GP in the form of films, sponges and internal fillers support the in vitro adhesion and proliferation of Schwann like cells.
Effective PEGylation of Iron Oxide Nanoparticles for High Performance In Vivo Cancer Imaging
Authors: Liu Dongfang , Wu Wei , Ling Jingjing , Wen Song , Gu Ning , Zhang Xizhi
Published: March 2011

A practical and effective strategy for synthesizing PEGylated superparamagnetic iron oxide nanoparticles (SPIONs) is established. In this strategy, poly(acrylic acid) (PAA) is combined with SPIONs via multiple coordination between the carboxylic groups of PAA and SPIONs, which introduces abundant carboxylic groups, then, α,ω‐diamino PEG is linked to SPIONs via the amidation of the carboxylic groups. The synthesized PEGylated SPIONs exhibit no cytotoxicity and high resistance to phagocytosis by macrophages in vitro as well as low uptake by the liver and spleen in vivo, which makes the SPIONs highly efficient in tumor imaging by magnetic resonance imaging (MRI) at a relatively low dose of SPIONs. These outstanding properties are largely due to the significant shielding effect of the dense PEG coating as well as the net neutral surface of the PEGylated SPIONs in physiological conditions. In summary, the PEGylated SPIONs prepared by this strategy exhibit great application potential in tumor imaging as MRI contrast agents targeting through enhanced permeability and retention (EPR) effect.
Reversible Electroaddressing of Self‐assembling Amino‐Acid Conjugates
Authors: Liu Yi , Kim Eunkyoung , Ulijn Rein V. , Bentley William E. , Payne Gregory F.
Published: March 2011

The triggered assembly of organic and biological materials in response to imposed electrical signals (i.e., electroaddressing) provides interesting opportunities for applications in molecular electronics, biosensing and nanobiotechnology. Recent studies have shown that the conjugation of aromatic moieties to short peptides often yields hydrogelator compounds that can be triggered to self‐assemble over a hierarchy of length scales in response to a reduction in pH. Here, we examined the capabilities of fluorenyl‐9‐methoxycarbonyl‐phenylalanine (Fmoc‐Phe) to electrodeposit in response to an electrochemically‐induced pH gradient generated at the anode surface. We report that the electrodeposition of Fmoc‐Phe; is rapid (minutes), can be spatially controlled in normal and lateral directions, and can be reversed by applying a brief cathodic current. Further more, we show that Fmoc‐Phe can be simultaneously deposited on one electrode address (anode) while it is being cathodically stripped from a separate electrode address of the same chip. Finally, we demonstrate that these capabilities can be extended for electroaddressing within microfluidic channels. The reversible assembly/disassembly of molecular gelators (Fmoc‐amino acids and Fmoc‐peptides) in response to spatiotemporally imposed electrical signals offers unique opportunities for electroaddressing that should be especially valuable for lab‐on‐a‐chip applications.
Domains Beyond the Grain Boundary
Authors: Ivry Yachin , Chu Daping , Scott James F. , Durkan Colm
Published: March 2011

Thin films of inorganic materials are used in diverse applications, typically in polycrystalline form due to their relatively simple production. We have used enhanced piezoresponse force microscopy to investigate the domain distribution within neighbouring grains in thin polycrystalline films of the ferroelectric–ferroelastic system lead zirconate titanate (PZT). We demonstrate that domains are organized into areas with a correlated alignment of the ferroelastic and ferroelectric domains, spanning multiple grain boundaries. We present five typical arrangements of such structures: azimuthal, radial, gradient, and short‐ and long‐ range linear domain organizations. Moreover, we discuss the mechanical and electrical constraints that dictate these structures.
Development of a simultaneous continuum and noncontinuum state estimator with application on a distillation process
Authors: Olanrewaju Moshood J. , Huang Biao , Afacan Artin
Published: March 2011

This study focuses on the development and application of a hybrid moving horizon estimator (HMHE) to achieve simultaneous estimation of both continuum and noncontinuum states in a constrained switching dynamic system. One of the major issues in a moving horizon estimation approach is the development of an arrival cost to summarize the effect of past and a prior information. In this work, we have developed a generalized arrival cost, which accounts for both continuum and noncontinuum states. A generalized hybrid state estimator, which can be used as a stand‐alone continuum state estimator, or as a simultaneous continuum and noncontinuum state estimator, is developed. The effects of constraints, process, and measurement noise levels, as well as a moving horizon length on the simultaneous estimation of both the continuum and noncontinuum states are analyzed. The effectiveness of the HMHE is demonstrated through simulation studies, while its practical reliability is tested by conducting experimental studies on a distillation column. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Understanding the influence of the ionic liquid composition and the surrounding phase nature on the stability of supported ionic liquid membranes
Authors: Hernández‐Fernández Francisco J. , de los Ríos Antonia P. , Tomás‐Alonso Francisca , Palacios José M. , Víllora Gloria
Published: March 2011

The industrial application of supported liquid membranes (SLMs) is still limited due to concerns about their stability. In a previous work, the selective separation of the substrates and products of a transesterification reaction was successfully carried out using Nylon membranes impregnated with ionic liquids (ILs). This article analyses the effect of both the IL composition and the nature of the surrounding phase on the stability of these SLMs to design highly stable supported ionic liquid systems. For this purpose, the stability of SLMs based on several ILs after immersion for a week in different feed/receiving phases was characterized using scanning electron microscopy combined with energy dispersive X‐ray (SEM‐EDX). The differential migration of the ILs observed from the membrane toward the surrounding phases was found to be correlated with the solubility of the ILs in the contacting phases. It was observed that SLM stability increased as the polarity of the solvent used as receiving phase decreased and as the hydrophilic character of the ILs used as liquid phase increased. Furthermore, the polymeric support was found to have a strongly stabilizing effect because losses of IL after immersion in a given surrounding phase were much lower than that derived from the solubility of the IL in this phase. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Targeting the p53 pathway to protect the neonatal ischemic brain
Authors: Nijboer Cora H. , Heijnen Cobi J. , van der Kooij Michael A. , Zijlstra Jitske , van Velthoven Cindy T.J. , Culmsee Carsten , van Bel Frank , Hagberg Henrik , Kavelaars Annemieke
Published: March 2011

Objective:

To investigate whether inhibition of mitochondrial p53 association using pifithrin‐μ (PFT‐μ) represents a potential novel neuroprotective strategy to combat perinatal hypoxic‐ischemic (HI) brain damage.

Methods:

Seven‐day‐old rats were subjected to unilateral carotid artery occlusion and hypoxia followed by intraperitoneal treatment with PFT‐μ, an inhibitor of p53 mitochondrial association or PFT‐α an inhibitor of p53 transcriptional activity. Cerebral damage, sensorimotor and cognitive function, apoptotic pathways (cytosolic cytochrome c, Smac/DIABLO, active caspase 3), and oxidative stress (lipid peroxidation and PARP‐1 cleavage) were investigated.

Results:

PFT‐μ treatment completely prevented the HI‐induced increase in mitochondrial p53 association at 3 hours and reduced neuronal damage at 48 hours post‐HI. PFT‐μ had long‐term (6–10 weeks post‐HI) beneficial effects as sensorimotor and cognitive outcome improved and infarct size was reduced by ∼79%. Neuroprotection by PFT‐μ treatment was associated with strong inhibition of apoptotic pathways and reduced oxidative stress. Unexpectedly, PFT‐μ also inhibited HI‐induced upregulation of p53 target genes. However, the neuroprotective effect of inhibiting only p53 transcriptional activity by PFT‐α was significantly smaller and did not involve reduced oxidative stress.

Interpretation:

We are the first to show that prevention of mitochondrial p53 association by PFT‐μ strongly improves functional outcome and decreases lesion size after neonatal HI. PFT‐μ not only inhibits mitochondrial release of cytochrome c, but also inhibits oxidative stress. We propose that as a consequence nuclear accumulation of p53 and transcription of proapoptotic target genes are prevented. In conclusion, targeting p53 mitochondrial association by PFT‐μ may develop into a novel and powerful neuroprotective strategy. ANN NEUROL 2011;00:000–000
Paper 1: The EUROCAT network—organization and processes†
Authors: Boyd Patricia A. , Haeusler Martin , Barisic Ingeborg , Loane Maria , Garne Ester , Dolk Helen
Published: March 2011

The European Surveillance of Congenital Anomalies (EUROCAT) is a network of population‐based congenital anomaly registries in Europe, funded by the European Union, which has been in operation for more than 30 years. It currently surveys more than 1.7 million births per year, including 31% of births in the European Union, and includes almost all population‐based European congenital anomaly registries as its members. EUROCAT member registries collect data, ascertained from multiple sources, on all major structural congenital and chromosomal anomalies. EUROCAT surveillance relates to three areas: prevalence, primary prevention, and prenatal screening.

This article describes the history of EUROCAT and gives an overview of the current methodology and work of EUROCAT covering the database content and management, coding and classification of anomalies, core surveillance, prevalence tables, statistical monitoring.

The monitoring of new developments in prenatal diagnosis, medication during pregnancy, use of folic acid, and investigation of clusters and exposures are overseen by working groups responsible for organizing research and producing regular reports. The EUROCAT Web site includes current data on prevalence rates and prenatal detection rates—an example of information useful to clinicians, public health service managers, and patients. Birth Defects Research (Part A), 2011. © 2011 Wiley‐Liss, Inc.
One‐step enzyme extraction and immobilization for biocatalysis applications
Authors: Cassimjee Karim Engelmark , Kourist Robert , Lindberg Diana , Wittrup Larsen Marianne , Thanh Nguyen Hong , Widersten Mikael , Bornscheuer Uwe T. , Berglund Per
Published: March 2011

An extraction/immobilization method for HIs6‐tagged enzymes for use in synthesis applications is presented. By modifying silica oxide beads to be able to accommodate metal ions, the enzyme was tethered to the beads after adsorption of Co(II). The beads were successfully used for direct extraction of C. antarctica lipase B (CalB) from a periplasmic preparation with a minimum of 58% activity yield, creating a quick one‐step extraction‐immobilization protocol. This method, named HisSi Immobilization, was evaluated with five different enzymes [Candida antarctica lipase B (CalB), Bacillus subtilis lipase A (BslA), Bacillus subtilis esterase (BS2), Pseudomonas fluorescence esterase (PFE), and Solanum tuberosum epoxide hydrolase 1 (StEH1)]. Immobilized CalB was effectively employed in organic solvent (cyclohexane and acetonitrile) in a transacylation reaction and in aqueous buffer for ester hydrolysis. For the remaining enzymes some activity in organic solvent could be shown, whereas the non‐immobilized enzymes were found inactive. The protocol presented in this work provides a facile immobilization method by utilization of the common His6‐tag, offering specific and defined means of binding a protein in a specific location, which is applicable for a wide range of enzymes.
Molecular dynamic simulation of wild type and mutants of the polymorphic amyloid NNQNTF segments of elk prion: Structural stability and thermodynamic of association
Authors: Berhanu Workalemahu M. , Masunov Artëm E.
Published: March 2011

A hexapeptide with amino acid sequence NNQNTF from the elk prion protein forms amyloid fibrils. Here we use molecular dynamic simulations of the oligomers and their single point glycine mutants to study their stability. In an effort to probe the structural stability and association thermodynamic in a realistic environment, all wildtype of NNQNTF polymorphic forms with different size and their corresponding double layer 5 strands single point glycine mutants were subjected to a total of 500 ns of explicit‐solvent molecular dynamics (MD) simulation. Our results show that the structural stability of the NNQNTF oligomers increases with increasing the number of β‐strands for double layers. Our results also demonstrated that hydrophobic interaction is the principle driving force to stabilize the adjacent β‐strands while the steric zipper is responsible for holding the neighboring β‐sheet layers together. We used MM‐PBSA approach free energy calculations to determine the role of nonpolar effects, electrostatics and entropy in binding. Nonpolar effects remained consistently more favorable in wild type and mutants reinforcing the importance of hydrophobic effects in protein‐protein binding. While entropy systematically opposed binding in all cases, there was no observed trend in the entropy difference between wildtype and glycine mutant. Free energy decomposition shows residues situated at the interface were found to make favorable contributions to the peptide‐peptide association. The study of the wild type and mutants in an explicit solvent may provide valuable insight for amyloid aggregation inhibitor design efforts. © 2011 Wiley Periodicals, Inc. Biopolymers 95: 573–590, 2011.
Design of a stirred multiwell bioreactor for expansion of CD34+ umbilical cord blood cells in hypoxic conditions
Authors: Luni Camilla , Zagallo Monica , Albania Lara , Piccoli Martina , Pozzobon Michela , De Coppi Paolo , Elvassore Nicola
Published: March 2011

Besides having a metabolic role, oxygen is recognized as an important signaling stimulus for stem cells. In hematopoiesis, hypoxia seems to favor stem cell self‐renewal. In fact, long‐term repopulating hematopoietic stem cells reside in bone marrow at concentrations as low as 1% oxygen. However, O2 concentration is difficult to control in vitro. Thermodynamically, we found significant differences between O2 solubility in different media, and in presence of serum. Furthermore, we verified that medium equilibration with a hypoxic atmosphere requires several hours. Thus, in a static culture, the effective O2 concentration in the cell immediate microenvironment is difficult to control and subject to concentration gradients. Stirred systems improve homogeneity within the culture volume. In this work, we developed a stirred bioreactor to investigate hypoxia effect on the expression of stem cell markers in CD34+ cells from umbilical cord blood. The stirring system was designed on top of a standard six‐well plate to favor continuity with conventional static conditions and transfer of culture protocols. The bioreactor volume (10 mL/well) is suitable for cell expansion and multiparametric flow cytometry analyses. First, it was tested at 21% O2 for biocompatibility and other possible effects on the cells compared to static conditions. Then, it was used to study c‐kit expression of CD34+ cells at 5% O2, using 21%‐O2 cultures as a control. In hypoxia we found that CD34+ cells maintained a higher expression of c‐kit. Further investigation is needed to explore the dynamics of interaction between oxygen‐ and c‐kit‐dependent pathways at the molecular level. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Bullying and (re)offending: Results from three samples in the Netherlands
Authors: Bijleveld Catrien , Van der Geest Victor , Hendriks Jan
Published: March 2011

Aim To investigate the relationship between bullying and (re)offending.

Method Carrying out bivariate analyses and multivariate analyses (controlling for Attention Deficit Hyperactivity Disorder (ADHD), parental abuse and neglect and impulsivity) on three large high‐risk groups (male and female juveniles with serious behaviour problems and a group of juvenile sex offenders).

Results Only the relationship between bullying victimisation and re‐offending in juvenile sex offenders is significant.

Conclusions Addressing bullying as a risk factor for re‐offending seems important in treatment of juvenile sex offenders. Copyright © 2011 John Wiley & Sons, Ltd.
Fenestration of a Gore Helex Septal Occluder device in a patient with diastolic dysfunction of the left ventricle
Authors: Kenny Damien , Cao Qi‐Ling , Hijazi Ziyad M.
Published: March 2011

We report successful deployment of a fenestrated Helex Septal Occluder in a 46‐year‐old lady with a moderate‐sized secundum atrial septal defect and elevated left‐ventricular end diastolic pressure secondary to renovascular hypertension. Initial balloon occlusion of the defect lead to significant rise in left atrial pressure. Creation of a 4‐mm fenestration offered controlled decompression of the left atrium while reducing the atrial shunt considerably. © 2011 Wiley‐Liss, Inc.