bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of pollutants and their correlation to meteorological conditions at a suburban site in the North China Plain
Authors: Xu W. Y. , Zhao C. S. , Ran L. , Deng Z. Z. , Liu P. F. , Ma N. , Lin W. L. , Xu X. B. , Yan P. , He X. , Yu J. , Liang W. D. , Chen L. L.
Published: March 2011

Abstract. North China Plain (NCP) is one of the most densely populated regions in China and has experienced enormous economic growth in the past decades. Its regional trace gas pollution has also become one of the top environmental concerns in China. Measurements of surface trace gases, including O3, NOx, SO2 and CO were carried out within the HaChi (Haze in China) project at Wuqing Meteorology Station, located between 2 mega-cities (Beijing and Tianjin) in the NCP, from 9 July 2009 to 21 January 2010. Detailed statistical analyses were made in order to provide information on the levels of the measured air pollutants and their characteristics. Gaseous air pollutant concentrations were also studied together with meteorological data and satellite data to help us better understand the causes of the observed variations in the trace gases during the field campaign. In comparison to measurements from other rural and background stations in the NCP, relatively higher concentrations were detected in Wuqing, presumably due to regional mixing and transport of pollutants. Local meteorology had deterministic impacts on air pollution levels, which have to be accounted for when evaluating other effects on pollutant concentrations. Trace gas concentrations showed strong dependence on wind, providing information on regional pollution characteristics. O3 mixing ratio also showed clear dependencies on temperature and relative humidity.
Enhancement and depletion of lower/middle tropospheric ozone in Senegal during pre-monsoon and monsoon periods of summer 2008: observations and model results
Authors: Jenkins G. S. , Ndiaye S. , Gueye M. , Fitzhugh R. , Smith J. W. , Kebe A.
Published: March 2011

Abstract. During the summer (8 June through 3 September) of 2008, nine ozonesondes are launched from Dakar, Senegal (14.75° N, 17.49° W) to investigate the impact of the Saharan Dust Layer (SAL) on ozone (O3) concentrations in the lower troposphere. Results during June (pre-monsoon period) show a reduction in O3, especially in the 850–700 hPa layer with SAL events. However, O3 concentrations are increased in the 950–900 hPa layer where the peak of the inversion is found and presumably the highest dust concentrations. We use the WRF-CHEM model to explore the causes of elevated O3 concentrations that appear to have a stratospheric contribution. During July and August (monsoon period), with the exception of one SAL outbreak, vertical profiles of O3 are well mixed with concentrations not exceeding 55 ppb between the surface and 550 hPa. In the transition period between 26 June and 2 July lower tropospheric (925–600 hPa) O3 concentrations are likely enhanced by enhanced biogenic NOx emissions from the Saharan desert and Sahelian soils following several rain events on 28 June and 1 July.
Surface modification of mineral dust particles by sulphuric acid processing: implications for CCN and IN abilities
Authors: Reitz P. , Spindler C. , Mentel T. F. , Poulain L. , Wex H. , Mildenberger K. , Niedermeier D. , Hartmann S. , Clauss T. , Stratmann F. , Sullivan R. C. , DeMott P. J. , Petters M. D. , Sierau B. , Schneider J.
Published: March 2011

Abstract. The ability of coated mineral dust particles to act as cloud condensation nuclei (CCN) and ice nuclei (IN) was investigated at LACIS (Leipzig Aerosol Cloud Interaction Simulator) during the FROST1- and FROST2-campaigns (Freezing of dust). Sulphuric acid was condensed on the particles which afterwards were optionally humidified, treated with ammonia vapour and/or heat. By means of aerosol mass spectrometry we found evidence that processing of mineral dust particles with sulphuric acid leads to surface modifications of the particles. These surface modifications are responsible for the observed reduction of the IN activation of the particles. The observed particle mass spectra suggest that different treatments lead to different chemical reactions on the particle surface. Possible chemical reaction pathways and products are suggested and the implications on IN and CCN efficiency of the treated dust particles are discussed.
Coupling ensemble weather predictions based on TIGGE database with Grid-Xinanjiang model for flood forecast
Authors: Bao H.-J. , Zhao L.-N. , He Y. , Li Z.-J. , Wetterhall F. , Cloke H. L. , Pappenberger F. , Manful D.
Published: March 2011

Abstract. The incorporation of numerical weather predictions (NWP) into a flood forecasting system can increase forecast lead times from a few hours to a few days. A single NWP forecast from a single forecast centre, however, is insufficient as it involves considerable non-predictable uncertainties and lead to a high number of false alarms. The availability of global ensemble numerical weather prediction systems through the THORPEX Interactive Grand Global Ensemble' (TIGGE) offers a new opportunity for flood forecast. The Grid-Xinanjiang distributed hydrological model, which is based on the Xinanjiang model theory and the topographical information of each grid cell extracted from the Digital Elevation Model (DEM), is coupled with ensemble weather predictions based on the TIGGE database (CMC, CMA, ECWMF, UKMO, NCEP) for flood forecast. This paper presents a case study using the coupled flood forecasting model on the Xixian catchment (a drainage area of 8826 km2) located in Henan province, China. A probabilistic discharge is provided as the end product of flood forecast. Results show that the association of the Grid-Xinanjiang model and the TIGGE database gives a promising tool for an early warning of flood events several days ahead.
Assessments of urban aerosol pollution in Moscow and its radiative effects
Authors: Chubarova N. Y. , Sviridenkov M. A. , Smirnov A. , Holben B. N.
Published: March 2011

Abstract. Simultaneous measurements by the collocated AERONET CIMEL sun/sky photometers at the Moscow State University Meteorological Observatory (MSU MO) and at the Zvenigorod Scientific Station (ZSS) of the A. M. Obukhov Institute of Atmospheric Physics during September 2006–April 2009 provide the estimates of the effects of urban pollution on various aerosol properties in different seasons. The average difference in aerosol optical thickness between MO MSU and ZSS, which can characterize the effect of aerosol pollution, has been estimated to be about dAOT = 0.02 in visible spectral region. The most pronounced difference is observed in winter conditions when relative AOT difference can reach 26%. The high correlation of the AOT's, the Angstrom exponent values and the effective radii between the sites confirms that natural processes are the dominating factor in the changes of the aerosol properties even over the Moscow megacity area. The existence of positive correlation between dAOT and difference in water vapor content explains many cases with large dAOT between the sites by the time lag in the airmass advection. However, after excluding the difference due to this factor, AOT in Moscow remains higher even in a larger number of cases (more than 75%) with the same mean dAOT = 0.02. Due to the negative average difference in aerosol radiative forcing at the TOA of about dARFTOA = −0.9 W m−2, the aerosol urban pollution provides a distinct cooling effect of the atmosphere. The PAR and UV irradiance reaching the ground is only 2–3% lower in Moscow due to the pollution effects, though in some situations the attenuation can reach 13% in visible and more than 20% in UV spectral region.
Measuring the 3-D wind vector with a weight-shift microlight aircraft
Authors: Metzger S. , Junkermann W. , Butterbach-Bahl K. , Schmid H. P. , Foken T.
Published: March 2011

Abstract. This study investigates whether the 3-D wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. Therefore we draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal wind components receive their greatest single amendment (14%, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical wind component is most of all improved (31%) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's aeroelastic wing (53%), as well as sudden changes in wing loading (16%) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the wind measurement: (a) A wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95% confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical wind component does not exceed 0.3 m s−1. (c) The comparison with ground based wind measurements yields an overall operational uncertainty (root mean square deviation) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical wind components. No conclusive dependence of the uncertainty on the wind magnitude (<8 m s−1) or true airspeed (ranging from 23–30 m s−1) is found. Hence our analysis provides the necessary basis to study the wind measurement precision and spectral quality, which is prerequisite for reliable eddy-covariance flux measurements.
Radio occultation bending angle anomalies during tropical cyclones
Authors: Biondi R. , Neubert T. , Syndergaard S. , Nielsen J.
Published: March 2011

Abstract. The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.
Development of a longterm dataset of solid/liquid precipitation
Authors: Chimani B. , Böhm R. , Matulla C. , Ganekind M.
Published: March 2011

Abstract. Solid precipitation (mainly snow, but snow and ice pellets or hail as well), is an important parameter for climate studies. But as this parameter usually is not available operationally before the second part of the 20th century and nowadays is not reported by automatic stations, information usable for long term climate studies is rare. Therefore a proxy for the fraction of solid precipitation based on a nonlinear relationship between the percentage of solid precipitation and monthly mean temperature was developed for the Greater Alpine Region of Europe and applied to the existing longterm high resolution temperature and precipitation grids (5 arcmin). In this paper the method is introduced and some examples of the resulting datasets available at monthly resolution for 1800–2003 are given.
Lack of P-limitation of phytoplankton and heterotrophic prokaryotes in surface waters of three anticyclonic eddies in the stratified Mediterranean Sea
Authors: Tanaka T. , Thingstad T. F. , Christaki U. , Colombet J. , Cornet-Barthaux V. , Courties C. , Grattepanche J.-D. , Lagaria A. , Nedoma J. , Oriol L. , Psarra S. , Pujo-Pay M. , Van Wambeke F.
Published: March 2011

Abstract. We investigated the identity of the limiting nutrient of the pelagic microbial food web in the Mediterranean Sea using nutrient manipulated microcosms during summer 2008. Experiments were carried out with surface waters at the center of anticyclonic eddies in the Western Basin, the Ionian Basin, and the Levantine Basin. In situ, the ratio of N to P was always higher in both dissolved and particulate organic fractions compared to the Redfield ratio, suggesting a relative P-starvation. In each experiment, four different treatments in triplicates (addition of ammonium, phosphate, a combination of both, and the unamended control) were employed and chemical and biological parameters monitored throughout a 3–4 day incubation. Temporal changes of turnover time of phosphate and ATP, and alkaline phosphatase activity during the incubation suggested that the phytoplankton and heterotrophic prokaryotes (Hprok) communities were not P-limited at the sites. Furthermore, statistical comparison among treatments at the end of the incubation did not support a hypothesis of P-limitation at the three study sites. In contrast, primary production was consistently limited by N, and Hprok growth was not limited by N nor P in the Western Basin, but N-limited in the Ionian Basin, and N and P co-limited in the Levantine Basin. Our results demonstrated the gap between biogeochemical features (an apparent P-starved status) and biological responses (no apparent P-limitation). We question the general notion that Mediterranean surface waters are limited by P alone during the stratified period.
Litter type affects the activity of aerobic decomposers in a boreal peatland more than site nutrient and water level regimes
Authors: Straková P. , Niemi R. M. , Freeman C. , Peltoniemi K. , Toberman H. , Heiskanen I. , Fritze H. , Laiho R.
Published: March 2011

Abstract. Peatlands are carbon (C) storage ecosystems sustained by a high water level (WL). High WL creates anoxic conditions that suppress the activity of aerobic decomposers and provide conditions for peat accumulation. Peatland function can be dramatically affected by WL drawdown caused by land-use and/or climate change. Aerobic decomposers are directly affected by WL drawdown through environmental factors such as increased oxygenation and nutrient availability. Additionally, they are indirectly affected via changes in plant community composition and litter quality. We studied the relative importance of direct and indirect effects of WL drawdown on aerobic decomposer activity in plant litter. We did this by profiling 11 extracellular enzymes involved in the mineralization of organic C, nitrogen, phosphorus and sulphur. Our study sites represented a three-stage chronosequence from pristine (undrained) to short-term (years) and long-term (decades) WL drawdown conditions under two nutrient regimes. The litter types included reflected the prevalent vegetation, i.e., Sphagnum mosses, graminoids, shrubs and trees. WL drawdown had a direct and positive effect on microbial activity. Enzyme allocation shifted towards C acquisition, which caused an increase in the rate of decomposition. However, litter type overruled the direct effects of WL drawdown and was the main factor shaping microbial activity patterns. Our results imply that changes in plant community composition in response to persistent WL drawdown will strongly affect the C dynamics of peatlands.
Role of net radiation on energy balance closure in heterogeneous grasslands
Authors: Shao C. , Chen J. , Li L. , Tenney G. , Xu W. , Xu J.
Published: March 2011

Abstract. Low energy balance closure (EBC) at a particular eddy-covariance flux site increased the uncertainties of carbon, water and energy measurements and thus hampered the urgent research of scaling up and modeling analysis through site combinations. A series of manipulative experiments were conducted in this study to explore the role of net radiation (Rn) in the EBC in relation to spatial variability of vegetation characteristics, source area, sensor type, and dome condition in the Inner Mongolian grassland of Northern China. At all three sites, the daytime peak residual fluxes of EBC were consistently about 100 W m−2 regardless of radiometers (i.e., REBS Q7.1 or CNR1). The spatial variability in net radiation was 19 W m−2 (5% of Rn) during the day and 7 W m−2 (16%) at night, with an average of 13 W m−2 (11%) from eight plot measurements across the three sites. Net radiation results were affected more by measurement source area in unclipped heterogeneous system than in clipped homogeneous vegetation. Large area measurement significantly (P<0.0001) increased by 9 W m−2 during the day and decreased by 4 W m−2 at night in unclipped treatments. With an increase in clipping intensity, net radiation decreased by 25 W m−2 (6% of Rn) at midday and 81 MJ m−2 (6%) during a growing season with heavier regular clipping than that in unclipped treatments. Additional effort in EBC between 9:00 and 15:00 LT is needed for future research because of high variation. Using this method, the EBC difference derived from the two types of net radiometers was only 6 W m−2. Results from Q7.1 with new domes were higher during the day but lower at night than those with used domes. Overall, the inclusion of the uncertainty in available energy accounted for 60% of the 100 W m−2 shortfalls in the lack of closure. Clearly, the unclosed energy balance at these three grassland sites remains significant, with unexplored mechanisms for future research.
Annual layering in the NGRIP ice core during the Eemian
Authors: Svensson A. , Bigler M. , Kettner E. , Dahl-Jensen D. , Johnsen S. , Kipfstuhl S. , Nielsen M. , Steffensen J. P.
Published: March 2011

Abstract. The Greenland NGRIP ice core continuously covers the period from present day back to 123 ka before present, which includes several thousand years of ice from the previous interglacial period, MIS 5e or the Eemian. In the glacial part of the core annual layers can be identified from impurity records and visual stratigraphy, and stratigraphic layer counting has been performed back to 60 ka. In the deepest part of the core, however, the ice is close to the pressure melting point, the visual stratigraphy is dominated by crystal boundaries, and annual layering is not visible to the naked eye. In this study, we apply a newly developed setup for high-resolution ice core impurity analysis to produce continuous records of dust, sodium and ammonium concentrations as well as conductivity of melt water. We analyzed three 2.2 m sections of ice from the Eemian and the glacial inception. In all of the analyzed ice, annual layers can clearly be recognized, most prominently in the dust and conductivity profiles. Part of the samples is, however, contaminated in dust, most likely from drill liquid. It is interesting that the annual layering is preserved despite a very active crystal growth and grain boundary migration in the deep and warm NGRIP ice. Based on annual layer counting of the new records, we determine a mean annual layer thickness close to 11 mm for all three sections, which, to first order, confirms the modeled NGRIP time scale (ss09sea). The counting does, however, suggest a longer duration of the climatically warmest part of the NGRIP record (MIS5e) of up to 1 ka as compared to the model estimate. Our results suggest that stratigraphic layer counting is possible basically throughout the entire NGRIP ice core provided sufficiently highly-resolved profiles become available.
Strength of forest-albedo feedback in mid-Holocene climate simulations
Authors: Otto J. , Raddatz T. , Claussen M.
Published: March 2011

Abstract. Reconstructions of the mid-Holocene climate, 6000 years before present, suggest that spring temperatures were higher at high northern latitudes compared to the pre-industrial period. A positive feedback between expansion of forest and climate persumably contributed to this warming. In the presence of snow, forests have a lower albedo than grass land. Therefore the expansion of forest likely favoured a warming in spring, counteracting the lower insolation at the mid-Holocene. We investigate this vegetation-climate interaction under mid-Holocene forcing with a comprehensive general circulation model (ECHAM5/JSBACH). We performed two sets of model simulations with either weak or strong reduction in surface albedo by snow-covered forest. The setup of simulations allowed us to calculate the pure contribution by the vegetation-climate interaction to the climate signal. Compared to the set with weak snow masking, the simulations with strong snow masking prevail a three times higher spring warming by 0.34 °C north of 60° N. The additional gain of forest is only 13%. We show that the parameterisation of the albedo of snow leads to uncertainties in the temperature signal but does not explain the strong spring warming suggested by previous simulations. We rather suggest that studies with coarser resolved representation of vegetation than in ECHAM5/JSBACH overestimated the increase in forest at the mid-Holocene and thus the strength of the vegetation climate.
A simplified treatment of surfactant effects on cloud drop activation
Authors: Raatikainen T. , Laaksonen A.
Published: March 2011

Abstract. Dissolved surface active species, or surfactants, have a tendency to partition to solution surface and thereby decrease solution surface tension. Activating cloud droplets have large surface-to-volume ratios, and the amount of surfactant molecules in them is limited. Therefore, unlike with macroscopic solutions, partitioning to the surface can effectively deplete the droplet interior of surfactant molecules. Surfactant partitioning equilibrium for activating cloud droplets has so far been solved numerically from a group of non-linear equations containing the Gibbs adsorption equation coupled with a surface tension model and an optional activity coefficient model. This can be a problem when surfactant effects are examined by using large-scale cloud models. Namely, computing time increases significantly due to the partitioning calculations done in the lowest levels of nested iterations. Our purpose is to reduce the group of non-linear equations to simple polynomial equations with well known analytical solutions. In order to do that, we describe surface tension lowering using the Szyskowski equation, and ignore all droplet solution non-idealities. It is assumed that there is only one surfactant exhibiting bulk-surface partitioning, but the number of non-surfactant solutes is unlimited. It is shown that the simplifications cause only minor errors to predicted bulk solution concentrations and cloud droplet activation. In addition, computing time is decreased at least by an order of magnitude when using the analytical solutions.
Assimilating SAR-derived water level data into a hydraulic model: a case study
Authors: Giustarini L. , Matgen P. , Hostache R. , Montanari M. , Plaza D. , Pauwels V. R. N. , De Lannoy G. J. M. , De Keyser R. , Pfister L. , Hoffmann L. , Savenije H. H. G.
Published: March 2011

Abstract. Satellite-based active microwave sensors not only provide synoptic overviews of flooded areas, but also offer an effective way to estimate spatially distributed river water levels. If rapidly produced and processed, these data can be used for updating hydraulic models in near real-time. The usefulness of such approaches with real event data sets provided by currently existing sensors has yet to be demonstrated. In this case study, a Particle Filter-based assimilation scheme is used to integrate ERS-2 SAR and ENVISAT ASAR-derived water level data into a one-dimensional (1-D) hydraulic model of the Alzette River. Two variants of the Particle Filter assimilation scheme are proposed with a global and local particle weighting procedure. The first option finds the best water stage line across all cross sections, while the second option finds the best solution at individual cross sections. The variant that is to be preferred depends on the level of confidence that is attributed to the observations or to the model. The results show that the Particle Filter-based assimilation of remote sensing-derived water elevation data provides a significant reduction to the model forecast uncertainty. Moreover, it is shown that the periodical updating of hydraulic models through the proposed assimilation scheme leads to an improvement of model predictions over several time steps. However, the performance of the assimilation depends on the skill of the hydraulic model and the quality of the observation data.
An efficient semi-distributed hillslope sediment model: the Anjeni in the sub humid Ethiopian Highlands
Authors: Tilahun S. A. , Engda T. A. , Legesse E. S. , Guzman C. D. , Zegeye A. D. , Collick A. S. , Rimmer A. , Steenhuis T. S.
Published: March 2011

Abstract. Prediction of sediment loss in Africa is not well developed. In most case models developed in western countries with a temperate climate do not perform well in the monsoon climate prevailing in Africa. In this paper we base our sediment prediction on a simple distributed saturated excess hydrology model that predicts surface runoff from bottom lands that become saturated during the rainy season and from severely degrade lands and interflow and base flow from the remaining portions of the landscape. By developing an equation that relate surface runoff and sediment concentration from runoff source areas assuming that base flow and interflow are sediment free, we were able to predict the daily sediment concentrations in a 113 ha Anjeni watershed in the Ethiopian Highlands with a Nash Sutcliffe efficiency ranging from 0.64–0.77 using only two calibrated sediment parameters. The daily flows were predicted with a Nash Sutcliffe efficiency values ranging from 0.80 to 0.84 based on 14% of the watershed consisted of degraded area as the only surface runoff source. The analysis seems to suggest that identifying the runoff source areas and predicting the surface runoff correctly is an important step in predicting the sediment concentration at least for the Anjeni watershed.
An ECOOP web portal for visualising and comparing distributed coastal oceanography model and in-situ data
Authors: Gemmell A. L. , Barciela R. M. , Blower J. D. , Haines K. , Harpham Q. , Millard K. , Price M. R. , Saulter A.
Published: March 2011

Abstract. As part of a large European coastal operational oceanography project (ECOOP), we have developed a web portal for the display and comparison of model and in-situ marine data. The distributed model and in-situ datasets are accessed via an Open Geospatial Consortium Web Map Service (WMS) and Web Feature Service (WFS) respectively. These services were developed independently and readily integrated for the purposes of the ECOOP project, illustrating the ease of interoperability resulting from adherence to international standards. The key feature of the portal is the ability to display co-plotted timeseries of the in-situ and model data and the quantification of misfits between the two. By using standards-based web technology we allow the user to quickly and easily explore over twenty model data feeds and compare these with dozens of in-situ data feeds without being concerned with the low level details of differing file formats or the physical location of the data. Scientific and operational benefits to this work include model validation, quality control of observations, data assimilation and decision support in near real time. In these areas it is essential to be able to bring different data streams together from often disparate locations.
Investigation of the Durability of Poly(Ether Urethane) in Water and Air
Authors: Braun Ulrike , Lorenz Edelgard , Maskos Michael
Published: March 2011

In this study some relevant aspects of the durability of an aromatic poly(ether urethanes) was investigated. Hydrolytic and oxidative treatments at increased temperatures were applied. The induced changes in the materials under investigation were characterized by complementary polymer characterisation methods, such as ATR-FTIR, DSC and mechanical testing. The thermal and hydrolytic treatment did not significantly affect the chemical composition of the materials. Changes can be observed in the microstructure of the materials.
Understanding Instability and Rupture of Poly(Alkyl-2-Cyanoacrylate) Capsules
Authors: Wischke Christian , Weigel Judith , Neffe Axel T. , Lendlein Andreas
Published: March 2011

Introduction

Poly(alkyl-2-cyanoacrylates) (PACAs) are degradable biomaterials that are clinically applied as surgical glue and studied as a matrix for particulate drug carriers such as nanoparticles or micro/nanocapsules. The stability of capsule walls is essential to avoid leakage of encapsulated compounds.

Methods

PACA capsules and (co)polymer films were prepared and characterization of their morphologies and thermal properties was performed.

Results

Thin-walled capsules that allow for a large internal volume to carry the payload were instable due to the high brittleness of PACA. Strategies to reduce the glass transition temperature (Tg) from values as high as ~120°C included plasticization by solvents and copolymerization approaches. By using the latter, the Tg of commonly used n-butylcyanoacrylate could be reduced up to 30 K, following predictions of mixed-system glass transition temperatures obtained, for example, by the Fox equation.

Conclusions

Thin-walled PACA capsules may allow for large payloads in the field of drug delivery and beyond, but require modifications of the PACA to improve capsule stability by more elastic capsule walls.
A Role of α′ Martensite Introduced by Thermo‐Mechanical Treatment in Improving Shape Memory Effect of an Fe‐Mn‐Si‐Cr‐Ni Alloy
Authors: Peng Huabei , Wen Yuhua , Liu Gang , Wang Chaoping , Li Ning
Published: March 2011

The evolution of α′ martensite with different thermo‐mechanical treatment and its effect on the shape memory effect were studied in an Fe‐14Mn‐5Si‐8Cr‐4Ni alloy. The α′ martensite was introduced by only 5% pre‐deformation, and its amount increased with increasing pre‐deformation up to 20%. The α′ martensite started to transform into austenite when the annealing temperature was 773 K. As the annealing temperature increased to 1 073 K, the α′ martensite almost transformed fully into austenite. The α′ martensite introduced by the thermo‐mechanical treatment could prevent collisions between different ε martensite bands during deformation. The intrusion of α′ martensite was another key reason that the stress‐induced ε martensite bands in Fe‐Mn‐Si based shape memory alloys formed in a domain‐specific manner in addition to that of uniformly distributed stacking faults after thermo‐mechanical treatment.
From Nanowheat to Nanograss: A Preparation Method to Achieve Free Standing Nanostructures Having a High Length/Diameter Aspect Ratio
Authors: Boehme Mario , Ensinger Wolfgang
Published: March 2011

The controlled fabrication of free standing, none collapsing nanostructures with a high length/diameter aspect ratio is reported. Usually these nanostructures synthesized using a template‐based method tends to collapse into wheat like structures using common techniques to separate the nanostructures from the template. Based on a novel process to inhibit the mechanism of collapsing nanostructures synthesized by template‐based deposition, nanograss‐like, and free standing nanostructures are obtained.
Functional Composite Materials Based on Chemically Converted Graphene (Adv. Mater. 9/2011)
Authors: Bai Hua , Li Chun , Shi Gaoquan
Published: March 2011

Graphene, a one‐atom layer of graphite, possesses a unique two‐dimensional structure and excellent mechanical, thermal, and electrical properties. Thus, it has been regarded as an important component for making various functional composite materials. Graphene can be prepared through physical, chemical and electrochemical approaches. Among them, chemical methods were tested to be effective for producing chemically converted graphene (CCG) from various precursors (such as graphite, carbon nanotubes, and polymers) in large scale and at low costs. Therefore, CCG is more suitable for synthesizing high‐performance graphene based composites. In this progress report, we review the recent advancements in the studies of the composites of CCG and small molecules, polymers, inorganic nanoparticles or other carbon nanomaterials. The methodology for preparing CCG and its composites has been summarized. The applications of CCG‐based functional composite materials are also discussed.
Kinetic analysis for crystal growth rate of NH4Cl in the NaCl‐MgCl2‐H2O system with a thermodynamic approach
Authors: Wang Daoguang , Li Zhibao
Published: March 2011

A growth kinetic model has been developed from a rigorous thermodynamic perspective to describe the crystal growth rates of NH4Cl on the basis of the difference of chemical potentials of NH4Cl at solid–liquid interface in aqueous NH4Cl, NH4Cl‐NaCl, and NH4Cl‐MgCl2 solutions. The solid–liquid equilibrium and activity coefficient of NH4Cl are calculated by the newly developed accurate Pitzer model with aid of Aspen Plus™ platform. The predictions of the resulting model are in good agreement with the experimental data published in literature and determined in this work at 283.15–333.15 K within the supersaturation up to 0.1. The kinetic model was subsequently used to analyze the effect of several operation variables, including temperature (283.15–333.15 K), supersaturation (up to 0.1), and NaCl or MgCl2 concentration (0∼2.5 mol kg−1), on the crystal growth rate of NH4Cl. The crystal growth rate of NH4Cl, with activation energy of 39 kJ mol−1, is strongly temperature‐dependent and increases with increasing temperature in the three systems investigated. The advantage of MgCl2 over NaCl on the recovery of NH4Cl is theoretically and experimentally illustrated from the thermodynamic and kinetic perspectives with the aid of the established model. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Optimal portfolio‐consumption choice under stochastic inflation with nominal and indexed bonds
Authors: Chou Ying‐Yin , Han Nan‐Wei , Hung Mao‐Wei
Published: March 2011

This research solves the intertemporal portfolio choice problems with and without interim consumption under stochastic inflation. We assume a one‐factor nominal interest rate and a one‐factor expected inflation rate, implying a two‐factor real interest rate in the economy. In contrast to other related research which adopts the one‐factor real interest rate model, the inflation‐indexed bond is not a redundant asset class even in a complete market. The infinitely risk‐averse investor would prefer to invest all her wealth in inflation‐indexed bonds maturing at the investment horizon. We also show that, with the two‐factor real interest rate model, the consumption‐wealth ratio is not determined by the real interest rate alone. The investor's consumption–wealth ratio is also affected by the nominal interest rate and expected inflation rate levels. The capital market is calibrated to U.S. stocks, bonds, and inflation data. The optimal weights show that aggressive investors hold more nominal bonds in order to earn the inflation risk premiums, while conservative investors concentrate on indexed bonds to hedge against the inflation risk. Copyright © 2011 John Wiley & Sons, Ltd.
2010 ASIS&T James M. Cretsos Leadership Award
Authors: Fulton Crystal
Published: March 2011

Reflecting on how participation in ASIS&T led to her winning the James M. Cretsos Leadership Award for 2010, Crystal Fulton focused on how ASIS&T's Special Interest Group/Information Needs, Seeking and Use (SIG/USE) has added to her career. Dr. Fulton reflected on early engaging discussions with the SIG/USE scholarly network and members' encouragement to become actively involved in SIG planning activities. This led to executive roles including chairmanship of the group in 2008‐2009 and serving on the SIG/USE Cabinet. During Dr. Fulton's chairmanship, the SIG celebrated its 10th anniversary with a range of activities aimed at membership development and communications and was named SIG‐of‐the‐Year for the second time. Dr. Fulton recognized the many colleagues who have supported her career development and SIG participation and encouraged ASIS&T members to become active in special interest group planning.
Collaborating – Key to providing complete answers online and off
Authors: Sacks Risa
Published: March 2011

Collaboration among independent information professionals is a worthwhile strategy for the right research project. Working together can supplement gaps in language, expertise and research skills. There is often a need for primary research, seeking information from original resources rather than online, but an info pro may be unable to pursue them due to confidentiality, impartiality, limited time or other reasons. A colleague skilled in primary research can fill in gaps and hard‐to‐access details, provide insight on attitudes and opinions, dig for clarification or more current information or even explain why online searching retrieves nothing on a topic. A successful collaboration demands sharing of information gathered and still needed, any limits to be honored and a reasonable timeframe. Organizations such as the Association of Independent Information Professionals provide directories of individuals with specific types of research skills.
Think strategically: Add value to your business
Authors: Bates Mary Ellen
Published: March 2011

For information professionals seeking to add value to their businesses, adapting to an evolving environment is critical. Identifying what to change starts by evaluating existing services, potential services to add or collaborate with, revenue sources, appealing opportunities and industry prospects. Both small and large projects offer value for information professionals. Smaller projects can fill gaps and smooth the income stream, while larger projects can offer expanded opportunities. One can nurture business opportunities by volunteering services, educating clients on services and capabilities, developing relationships based on confidence and trust and serving as a consultant.
Strategic communications: Making your marketing and website content work for your business
Authors: Carrero Andrea C.
Published: March 2011

Effective business marketing communications require that messages be tailored for the audience, reflecting an understanding of the reader's concerns and motivations. The message must directly address what is most relevant for the audience and inspire further interest in the information services or products offered. It must be written in sharp and concise language and should conclude with a call to action. The basic message can be presented through a variety of media, including brochures and articles, websites and webinars, Twitter messages and training events, and more, always branding the business consistently.
Challenges with context
Authors: Haller Thom
Published: March 2011

IA Column

Recollections of an information architecture class focusing on user experience brought out the importance of understanding context. One site overhaul project revealed internal problems rising from contrasting views of the stakeholders. The project served as a lesson about choices in site content and structure made by information architects to support end user information needs and organizational goals, rather than showcasing creative designs and personal preferences. Information architects should ask themselves how their choices differ when working with an organization that is clear about its goals for supporting knowledge, not simply presenting data without meaning or purpose.
Development of activity generation and behavior observation systems for distance learning
Authors: Dow Chyi‐Ren , Li Yi‐Hsung , Huang Lu‐Hui , Hsuan Pa
Published: March 2011

Distance learning and e‐learning are popular and widely used technology in today's teaching environment; monitoring systems allow teachers to assess the learning state of their students. This study proposes a development of activity generation and behavior observation systems that allows teachers to assess the learning activities of their students. We use the concept of deterministic finite automaton to define learning activities. In the proposed system, teachers only need to click the drop‐down list items to manage learning activities. The proposed system also generates an activity recognizer after defining the activity. The activity recognizer can parse student‐learning logs allowing teachers to get the real‐time learning activities of students. When students are in abnormal learning states, teachers can immediately provide them with active guidance. The experiments in this study demonstrate the feasibility and effectiveness of the proposed system. Experimental results show that students received higher grades and exhibited less abnormal learning with the proposed monitoring system. These results demonstrate that the proposed system provides teachers with a convenient interface for assisting their students. The proposed monitoring system improves the learning outcomes of students. © 2011 Wiley Periodicals, Inc. Comput Appl Eng Educ 22: 52–62, 2014
Study of the separation of simple binary and ternary mixtures of aromatic compounds
Authors: Binous Housam , Al‐Mutairi Eid , Faqir Naim
Published: March 2011

Consider binary and ternary mixtures of aromatic compounds composed of benzene/toluene and benzene/toluene/p‐xylene, respectively. The present study shows how one can apply both mass and energy balance equations in order to understand the separation of such ideal mixtures by distillation. An adiabatic flash distillation problem is solved graphically for a mixture composed of benzene/toluene. Rigorous resolution of a steady‐state binary distillation problem, using Mathematica® and the same benzene/toluene mixture, shows perfect agreement with results obtained using HYSYS. Results of a dynamic simulation involving the solution of a relatively large system of differential algebraic equations are presented and discussed for the benzene/toluene mixture. SIMULINK© and Mathematica® are used to perform control of this binary distillation column. Finally, a steady‐state simulation of a simple multicomponent mixture, composed of benzene/toluene/p‐xylene, is studied and some qualitative results are drawn from both the temperature and composition profiles. © 2011 Wiley Periodicals, Inc. Comput Appl Eng Educ 22: 87–98, 2014
Influence of Trivalent Metal Ions on the Metastable Zone Width of Ammonium Sulfate
Authors: Buchfink R. , Ulrich J.
Published: March 2011

The metastable zone width (MZW) is a vital parameter for the design of industrial crystallization processes of inorganic salts and could be affected by the addition of impurities. Here, the effect of the trivalent ions Fe3+, Cr3+, and Al3+ on the MZW of ammonium sulfate was observed. All the experiments were performed with the help of ultrasonic speed measurements. Impurity concentrations up to 100 ppm at a solution pH of 4 increase the MZW depending on the metal ion. The pH value also showed a major influence on the effect of trivalent metal impurities. The results were compared to the distribution of metal‐aquo‐complexes existing in aqueous solutions contaminated by trivalent metal ions. The distribution was determined by using the computer‐based simulation software Hyss. The first hydrolysis product was identified to be active in widening the MZW.
Emulsion Fractionation of Coconut Oil: A New Fractionation Technology
Authors: Chaleepa K. , Ulrich J.
Published: March 2011

Fractional crystallization technologies are commonly used to modify the triglyceride compositions of fats in order to extend their utilization. Improvements in solid fat properties to stabilize fat products are of great interest. For this purpose, a new fractionation process based on crystallization of low‐viscous emulsions, the so‐called emulsion fractionation process, has been developed using model emulsions of coconut oil, water, and sucrose ester laurate (L‐195). The experimental results confirm the superior performance in phase separation of this new concept, leading to a higher quality and quantity of coconut stearin in comparison to conventional processes. Since the emulsion fractionation process involves only water and a food emulsifier, it is environmentally friendly and has the potential to be a promising alternative in oil and fat fractionation technologies.
Fractionation of Organic and Inorganic Compounds from Black Liquor by Combining Membrane Separation and Crystallization
Authors: Niemi H. , Lahti J. , Hatakka H. , Kärki S. , Rovio S. , Kallioinen M. , Mänttäri M. , Louhi‐Kultanen M.
Published: March 2011

Separation of organic and inorganic compounds from black liquor was investigated. Black liquor from the pulp and paper industry contains hundreds of different compounds and several high‐value organic chemicals are formed during alkaline pulping. These organic compounds can be used in the fine chemicals, pharmaceutical and food industries. The main aim of this study was to recover and purify high value‐added organic compounds (organic acids) from lignin and inorganic compounds by combining membrane filtration, acid precipitation and cooling crystallization. The effect of membrane filtration on the efficiency of precipitation and crystallization was also studied. A number of separation methods were studied under a variety of operating conditions. The results showed that a combination of membrane separation and crystallization is an efficient method for recovering and purifying valuable organic compounds in black liquor. The amount of major impurities in black liquor could be reduced significantly.
Exploring the Conformational and Biological Versatility of β‐Turn‐Modified Gramicidin S by Using Sugar Amino Acid Homologues that Vary in Ring Size
Authors: Knijnenburg Annemiek D. , Tuin Adriaan W. , Spalburg Emile , de Neeling Albert J. , Mars‐Groenendijk Roos H. , Noort Daan , Otero José M. , Llamas‐Saiz Antonio L. , van Raaij Mark J. , van der Marel Gijs A. , Overkleeft Herman S. , Overhand Mark
Published: March 2011

Monobenzylated sugar amino acids (SAAs) that differ in ether ring size (containing an oxetane, furanoid, and pyranoid ring) were synthesized and incorporated in one of the β‐turn regions of the cyclo‐decapeptide gramicidin S (GS). CD, NMR spectroscopy, modeling, and X‐ray diffraction reveal that the ring size of the incorporated SAA moieties determines the spatial positioning of their cis‐oriented carboxyl and aminomethyl substituents, thereby subtly influencing the amide linkages with the adjacent amino acids in the sequence. Unlike GS itself, the conformational behavior of the SAA‐containing peptides is solvent dependent. The derivative containing the pyranoid SAA is slightly less hydrophobic and displays a diminished haemolytic activity, but has similar antimicrobial properties as GS.