bluuebunny/crossref_metadata_2025 huggingface dataset:
Injection Molding of LDPE/BaSO4 Blends
Authors: Shearer G. , Tzoganakis C. , Penlidis A. , Rempel G. L.
Published: December 2013

The injection mold filling behavior of a blend of low density polyethylene (LDPE) and barium sulphate (BaSO4) was studied experimentally and compared with that of pure LDPE. The method of short shots was used to analyze the mold filling behavior. An experimental study using a full factorial design was implemented with the following factors: mold temperature, injection speed and injection time. Experimental results and computer simulation predictions of the mold filling stage were found to be in acceptable agreement. The produced short shots with the LDPE/BaSO4 blend have significantly lower percentages of volume filled than those of the corresponding short shots with the pure LDPE. The increase in the melt viscosity and density of the polymer resin with the addition of BaSO4 cannot be neglected when producing injection molded articles with LDPE/BaSO4 blends. To study the deviations between the experimental results and the computer simulation predictions, a factorial numerical study was completed. The results show that the simulation predictions are significantly affected by the accuracy of the polymer material properties.
Towards a 3-D Finite Element Model for the Gas-Assisted Injection Moulding Process
Authors: Haagh G. A. A. V. , Zuidema H. , van de Vosse F. N. , Peters G. W. M. , Meijer H. E. H.
Published: December 2013

The Gas-Assisted Injection Moulding process (GAIM) offers a number of advantages, which are almost without exception related to the negligible pressure drop in the gas core of the moulded product. Accurate prediction of the gas distribution inside GAIM products is, however, still a major problem to be solved. As gas penetration is governed by three-dimensional phenomena, one has to resort to numerical simulations to analyse the process. Therefore, a numerical model for GAIM simulations has been developed, based on a physical, rather than on an empirical approach. The model employs a pseudo-concentration method in order to avoid elaborate three-dimensional remeshing, and has been implemented in a finite element program.

Simulation results for two-dimensional test cases representing typical GAIM situations prove that the model covers most of the important aspects of gas injection. A pilot simulation for a simple three-dimensional mould demonstrates that the model is able to deal with three-dimensional GAIM. Further refinement of the model will mainly concern the implementation of faster and less memory-consuming solution methods.
Melt Temperatures and Residence Times in an Extruder by Infrared Spectroscopy
Authors: Nietsch T. , Cassagnau P. , Michel A.
Published: December 2013

This article presents melt temperature measurements with an infrared thermometer during extrusion and investigates the influence by the surface emissivity and the rotating screw. This influence can be used for on line residence time measurements in the extruder line, to measure the number of revolutions of the screw, and to measure both the surface temperature and the bulk's temperature.

The results show that colouring the PE with a high emisffisivity tracer allows us to measure the melt's surface temperature and minimise the influence of the rotating screw. Its influence is weaker in complete filled section as in partial filled sections of the extruder and the mean bulk's temperature is measured when the emissivity is lower than one.

Furthermore it is shown that it is possible to measure the residence time distribution on line with an infrared thermometer, by taking advantage of its sensibility on a changing surface emissivity. Measurements with classical methods shows the same residence time distribution as obtained with the infrared spectroscopy. The advantage of this method is its wide range of applications, such like as the use in pressure zones, for a wide range of temperature and to measure on line the local residence time distribution all along the screw.
Distributed Crystallinity Control during Cast Film Extrusion
Authors: Leephakpreeda T. , Batur C.
Published: December 2013

The properties of polymer material can be shaped by crystallinity distribution during the film extrusion process. This paper addresses the implementation of design sensitivity analysis to determine the process inputs which can generate the desired crystallinity distribution. To achieve such a goal, the performance index is defined in terms of the difference between the desired and the actual crystallinity distributions. The sensitivity of the performance index to process inputs is determined in order to update these process inputs in every iteration of optimization. The design sensitivity analysis presented here allows a systematic movement through the search space to reach a sub-optimal set of process inputs. The simulation results show that the proposed methodology can determine the process inputs in order to generate the crystallinity distribution close to the desired one.
The Occurrence of Flow Marks during Injection Molding of Linear Polyethylene
Authors: Heuzey M. C. , Dealy J. M. , Gao D. M. , Garcia-Rejon A.
Published: December 2013

Injection molded parts often show several types of surface defect. It has been hypothesized that wall slip is associated with some of these defects. Wall slip of molten plastics has been observed above a certain critical shear stress in rheological measurements. The objectives of the proposed research were to analyze the occurrence of flow marks during the injection molding of linear polyethylene and evaluate its possible relation to wall slip. Various variables were studied in terms of their influence on flow mark formation: mold thickness, mold temperature, melt temperature, gate, injection speed and TeflonTM and silicone oil coatings. It was found that injection speed is the controlling factor for the generation of flow marks during injection molding of the linear polyethylenes studied. Since one of the resin studied had shown no tendency to slip in capillary flow experiments, and since a Teflon TM coating on the mold walls did not affect the occurrence of flow marks, we conclude that there is no relationship between wall slip and the generation of flow marks. Microscopic observation of molded surfaces suggests instead that flow marks result from the filamentaton and stretching of semi-solidified material in the neighborhood of the three-phase contact line.
Modeling Solids Conveying in Polymer Extruders
Authors: Yamamuro J. A. , Penumadu D. , Campbell A.
Published: December 2013

Modeling solids conveyance in a polymer extruder is difficult because it is a highly complex process. The solids are subjected to pressure and temperature gradients from the hopper through a heated section, where it is melted into a liquid over a finite distance. The polymer material possesses shear strength, which causes an anisotropic stress distribution to exist between the down channel pressure and the normal stresses on the flights, barrel and core. A new formulation incorporating anisotropic stress states into an isotropic model is presented. Assumptions regarding the direction of the driving force applied by the screw have been examined in addition to coupling its direction with the orientation of the barrel friction force. These assumptions allow the new model to provide increased nonlinearity and flexibility to accurately predict extruder output over wide variations with discharge pressure. A new parameter, the skew angle, is introduced in the proposed model. Predictions of extruder output for varying discharge pressures and barrel temperatures show excellent agreement with experimental data.
Pumping Characteristics of an Intermeshing Co-rotating Twin Screw Extruder
Authors: Wang N. H. , Sakai T. , Hashimoto N.
Published: December 2013

The pumping characteristics of several types of screw elements for an intermeshing co-rotating twin screw extruder (ICoTSE) were experimentally studied using molten polystyrene (PS) as a typical non-Newtonian fluid in “LABOTEX30α”. Here, the throughput was regarded as the remainder of drag flow minus pressure flow, based on the previous theoretical and experimental studies with regard to either single or twin-screw extruders. Therefore, the relationship between the throughput and the pressure gradient for a given screw geometry was approximately expressed as a linear dimensionless relation containing two so-called pumping-characteristic parameters which depend on the element geometry and degree of departure of the used fluid from the Newtonian fluid.

The pumping-characteristic parameters for two right-hand flighted screw elements (RF) with leads of 0.938D and 0.703D, a neutral kneading disk (NK) and a blister ring (BR) were experimentally determined, and the RF with a lead of 0.938D was taken as an example to observe the effect of the clearance between it and the barrel wall on its pumping-characteristic. The results show that the linear relationship between the dimensionless throughput and the dimensionless pressure gradient for each type of the screw elements used here is a good approximation, and the clearance in the range used here greatly affects the pumping characteristic of the RF.

Moreover, the degree of filling and the pressure profile in two kinds of screw configurations used for water-injection foaming devolatilization, which consist of elements with different diameters but with the same dimensionless geometry as those used in this work, were predicted and discussed by using the determined pumping-characteristic parameters under the conditions of given throughput of molten PS and screw speed.
Sintering Rheology of Semi-Crystalline Polymers
Authors: Liu S.-J.
Published: December 2013

The focus of this study is to investigate the sintering mechanism of polyethylene. Experiments were conducted to observe the high temperature sintering behaviors of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). It was found that the sintering of polyethylene follows Frenke's model and is basically a Newtonian viscous flow. The sintering rate decreases as the viscosity of the resin increases. By increasing the temperature, one can shorten the time needed to complete the coalescence process. Experimental investigation will provide an improved understanding of the sintering of semi-crystalline polymers.
Interactions in Binary and Ternary Polyolefin Blends
Authors: Hénaut I. , Vergnes B. , Agassant J. F. , Haudin J. M.
Published: December 2013

A way for the recovery of plastic waste is the reprocessing. As they cannot be easily separated, the reprocessing of polyolefins appears as a special case of the processing of polymer blends. In order to understand the basic phenomena involved in these systems, binary and ternary blends are prepared from a high density polyethylene, a linear low density polyethylene, and a random ethylene-propylene copolymer. In a first step, the interactions between the different polyolefins are characterized in laboratory experiments (differential scanning calorimetry, optical microscopy, small-angle light scattering, wide-angle X-ray diffraction, mechanical properties). Then, it is shown that the original poor mechanical properties of the blends can be largely improved by optimizing the processing conditions. Finally, an extrapolation of these results to real plastic waste is presented.
Crystal Orientation in Injection Moldings of Talc-filled Polyolefins
Authors: Fujiyama M.
Published: December 2013

Crystal orientation states in injection moldings of talc-filled polyolefins have been studied. Talc-filled polypropylene injection moldings show an unusual crystal orientation, in which the plate planes of talc particles are aligned parallel to the molding surface, the c- and a*-axes of polypropylene crystals are bimodally oriented to the flow direction, and the b-axes are oriented to the thickness direction. In injection moldings of talc-filled high density polyethylene and polybutene-1, although talc particles are aligned parallel to the molding surface, polymer crystals do not show any unusual orientation. Only talc-filled polypropylene injection moldings show the unusual crystal orientation.
Stress-Strain and Volume Change Characteristics of an Assemblage of Polymer Pellets
Authors: Penumadu D. , Yamamuro J. A. , Abrantes A. E. , Campbell G. A.
Published: December 2013

A series of experiments were performed on an assembly of four commercially available polymer pellets at room temperature. An automated deformation controlled triaxial testing system was used for the entire testing program. Lubricated end platens were used to assure uniform strain conditions during the application of compressive loading on the confined cylindrical specimen of a given polymer pellet type at a target bulk density. The test results in terms of the deviator stress-strain and volume change characteristics of polymer pellets were obtained for use in the modeling and analysis of solids conveying in plasticating screw extruders. Testing procedures are described that can be used routinely to obtain the strength and deformation behavior of an assemblage polymer pellets. The deviator stress-axial strain and volumetric strain-axial strain curves are presented for four confining stress levels (l00, 200, 300 and 400 k Pa) for these materials using both dry and saturated specimens. The water saturated specimens were used in parallel for obtaining reliable measurements of the volumetric strain variation during the application of deviator stress. The effect of using water as the pore fluid on the mechanical behavior was also discussed. The angles of internal friction of these four polymeric materials were determined and the use of Mohr-Coulomb failure criteria was evaluated. These confining pressure dependent friction angles are compared with the angle of repose measurements. The stress transfer coefficients as a function of wall friction for the potential states of confinement of these polymer pellets in the solids conveying portion of an extruder are also summarized.
Consistency and Flexibility of Multi Cavity Melt Control
Authors: Kapoor D. , Kazmer D.
Published: December 2013

The quality of injection moulded products is determined by a complex coupling between polymer properties, mould geometry, and process dynamics. To increase the flexibility and consistency of the injection moulding process, a method was devised to simultaneously control cavity pressure at multiple locations in a mould. This control was achieved by installing multiple dynamic valve stems into the feed system of a hot runner manifold, each of which can control polymer flow. This system was used in a commercial application with four gates to deliver consistent product quality and provide manufacturing-stage flexibility. Across all eleven measured dimensions, the process capability index Cp increased between 50 and 400%. Also, multiple dimensions could be independently and simultaneously adjusted by locally controlling material shrinkage.
A Review of Cavity Design for Kerr Lens Mode-Locked Solid-State Lasers
Authors: Yefet Shai , Pe'er Avi
Published: December 2013

We provide a critical review of the fundamental concepts of Kerr lens mode-locking (KLM), along with a detailed description of the experimental considerations involved in the realization of a mode-locked oscillator. In addition, we review recent developments that overcome inherent limitations and disadvantages in standard KLM lasers. Our review is aimed mainly at readers who wish to realize/maintain such an oscillator or for those who wish to better understand this major experimental tool.
Welcome to Bioengineering: A New Open-Access Journal
Authors: Guiseppi-Elie Anthony
Published: December 2013

It is my great pleasure to welcome you to a new open access journal, Bioengineering, which represents a scope that fits squarely with the core expertise and growing ambitions and interests of bioengineers globally. Of particular interest are the transdisciplinary and translational research represented by the activities within centers and institutes where the biological sciences and engineering disciplines cohabit seamlessly for a focus on solutions to global challenges in human, veterinary and ecological health, bioenergy, bioprocess and sustainability. Bioengineering emphasizes the publication of novel and high quality peer reviewed articles via an open access platform. The scope includes: [...]
Exploiting a Reference Genome in Terms of Duplications: The Network of Paralogs and Single Copy Genes in Arabidopsis thaliana
Authors: Sangiovanni Mara , Vigilante Alessandra , Chiusano Maria
Published: December 2013

Arabidopsis thaliana became the model organism for plant studies because of its small diploid genome, rapid lifecycle and short adult size. Its genome was the first among plants to be sequenced, becoming the reference in plant genomics. However, the Arabidopsis genome is characterized by an inherently complex organization, since it has undergone ancient whole genome duplications, followed by gene reduction, diploidization events and extended rearrangements, which relocated and split up the retained portions. These events, together with probable chromosome reductions, dramatically increased the genome complexity, limiting its role as a reference. The identification of paralogs and single copy genes within a highly duplicated genome is a prerequisite to understand its organization and evolution and to improve its exploitation in comparative genomics. This is still controversial, even in the widely studied Arabidopsis genome. This is also due to the lack of a reference bioinformatics pipeline that could exhaustively identify paralogs and singleton genes. We describe here a complete computational strategy to detect both duplicated and single copy genes in a genome, discussing all the methodological issues that may strongly affect the results, their quality and their reliability. This approach was used to analyze the organization of Arabidopsis nuclear protein coding genes, and besides classifying computationally defined paralogs into networks and single copy genes into different classes, it unraveled further intriguing aspects concerning the genome annotation and the gene relationships in this reference plant species. Since our results may be useful for comparative genomics and genome functional analyses, we organized a dedicated web interface to make them accessible to the scientific community.
Optimizing the Use of Secchi Depth as a Proxy for Euphotic Depth in Coastal Waters: An Empirical Study from the Baltic Sea
Authors: Luhtala Hanna , Tolvanen Harri
Published: December 2013

Potential zone for photosynthesis in natural waters is restricted to a relatively thin illuminated surface water layer. The thickness of this layer is often indirectly estimated by measuring the depth in which 1% of the photosynthetically active radiation entering the water remains. This depth is referred to as the euphotic depth. A coarser way to evaluate the underwater light penetration is to measure the Secchi depth, which is a visual measure of water transparency. The numerical relationship between these two optical parameters, i.e., conversion coefficient m, varies according to the changes in the optical properties of water, especially in transitional coastal waters. The aim of our study is to assess which is the most suitable criterion to base these coefficients on. We tested nine methods, seven of which were locally calibrated with our own in situ data from the optically heterogeneous Baltic Sea archipelago coast of SW Finland. We managed to significantly improve the accuracy of modeling euphotic depths from Secchi depths by using scalable and locally calibrated methods instead of a single fixed coefficient. The best results were achieved by using methods, either continuous functions or series of constants, which are based on water transparency values.
Anti-Inflammatory Effects of 4-Methylcyclopentadecanone on Edema Models in Mice
Authors: Ma Yukui , Li Yue , Li Xiufeng , Wu Yingliang
Published: December 2013

The present study evaluated the anti-inflammatory effects of 4-methylcyclopentadecanone (4-MCPC) on edema models in mice and aimed to determine the safety of 4-MCPC after acute exposure. The acute toxicity of 4-MCPC was evaluated by oral administration to rats of single doses of 0, 5, 50, 500 and 5000 mg/kg. Toxic symptoms were observed for 14 days. The anti-inflammatory activity was evaluated in xylene-induced mouse ear edema and carrageenan-induced mouse paw edema. The animals were treated with 4-MCPC once every day for seven consecutive days. Edema index, % inhibition, IL-1β, TNF-α, PGE2 and MPO levels in paws were detected after the treatment with xylene or carrageenan. Our results indicated that the LD50 value of 4-MCPC in rats is greater than 5000 mg/kg. The ED50 of 4-MCPC in xylene-induced mouse ear edema model was 7.5 mg/kg. 4-MCPC (8 or 16 mg/kg) remarkably inhibited carrageenan-induced mouse paw edema. Further study revealed that 4-MCPC treatment also decreased IL-1β, TNF-α, PGE2 and MPO levels in mice paws. Intragastric administration of 4-MCPC exhibited more significant anti-inflammatory activity than muscone at a dose of 16 mg/kg. Taken together, our results suggest that 4-MCPC has potent anti-inflammatory activity and the mechanisms might be related to the decreases of the levels of IL-1β, TNF-α, PGE2 and MPO in inflamed paws.
The Effects of H2S on the Activities of CYP2B6, CYP2D6, CYP3A4, CYP2C19 and CYP2C9 in Vivo in Rat
Authors: Wang Xianqin , Han Anyue , Wen Congcong , Chen Mengchun , Chen Xinxin , Yang Xuezhi , Ma Jianshe , Lin Guanyang
Published: December 2013

Hydrogen sulfide (H2S) is a colorless, flammable, extremely hazardous gas with a “rotten egg” smell. The human body produces small amounts of H2S and uses it as a signaling molecule. The cocktail method was used to evaluate the influence of H2S on the activities of CYP450 in rats, which were reflected by the changes of pharmacokinetic parameters of five specific probe drugs: bupropion, metroprolol, midazolam, omeprazole and tolbutamide, respectively. The rats were randomly divided into two groups, control group and H2S group. The H2S group rats were given 5 mg/kg NaHS by oral administration once a day for seven days. The mixture of five probes was given to rats through oral administration and the blood samples were obtained at a series of time-points through the caudal vein. The concentrations of probe drugs in rat plasma were measured by LC-MS. In comparing the H2S group with the control group, there was a statistically pharmacokinetics difference for midazolam and tolbutamide; the area under the plasma concentration-time curve (AUC) was decreased for midazolam (p < 0.05) and increased for tolbutamide (p < 0.05); while there was no statistical pharmacokinetics difference for bupropion, metroprolol and omeprazole. H2S could not influence the activities of CYP2B6, CYP2D6 and CYP2C19 in rats, while H2S could induce the activity of CYP3A4 and inhibit the activity of CYP2C9 in rats.
Characterization of Flavonoids in the Ethomedicine Fordiae Cauliflorae Radix and Its Adulterant Millettiae Pulchrae Radix by HPLC-DAD-ESI-IT-TOF-MSn
Authors: Fan Lan-Lan , Yi Tao , Xu Feng , Zhang Ya-Zhou , Zhang Jian-Ye , Li Dian-Peng , Xie Yang-Jiao , Qin Shan-Ding , Chen Hu-Biao
Published: December 2013

Fordiae Cauliflorae Radix (FC, the root of Fordia cauliflora Hemsl) and Millettiae Pulchrae Radix [MP, the root of Millettia pulchra (Benth.) Kurz var. laxior (Dunn) Z. Wei], which go under the same local name of “Daluosan”, have long been used in Southern China for the treatment of stroke, paralysis, dementia in children, Alzheimer’s disease and other diseases. The same local name and similar functions always confuse users. To further utilize these two ethnodrugs and identify them unambiguously, an HPLC-DAD-ESI-IT-TOF-MSn method was developed to separate and characterize the flavonoids in FC and MP. A total of 41 flavonoids were detected, of which six compounds were identified by comparing their retention time and MS data with those of the reference standards, and the others were tentatively identified based on their tandem mass spectrometry data obtained in the positive ion detection mode. Nineteen of these characterized compounds are reported from these two plants for the first time.
Application of a Land Surface Model Using Remote Sensing Data for High Resolution Simulations of Terrestrial Processes
Authors: Choi Hyun
Published: December 2013

Most current land surface models (LSMs) coupled to regional climate models (RCMs) have been implemented at the several tens of kilometer spatial scales. Modeling land surface processes in LSMs at a finer resolution is necessary for improvements in terrestrial water and energy predictions especially for small catchments. This study has therefore assessed the applicability of high-resolution simulations for terrestrial processes to a small study basin from the Common Land Model (CoLM) using 1-km surface boundary conditions (SBCs) based on remote sensing products. The performance of the CoLM simulations at finer (1-km) and coarser (30-km) resolutions are evaluated for daily runoff and land surface temperature results which have a significant influence on the terrestrial water and energy cycles. The daily stream water temperature is also estimated by a linear regression function of the 1-km daily land surface temperature prediction. The daily stream runoff and temperature results are compared with observations from a stream gauge station, and the daily land surface temperature prediction is compared with the 1-km remote sensing product. It is observed that the high-resolution CoLM results can reasonably capture seasonal variations in both daily runoff and temperatures crucial to the terrestrial water and energy budget.
Commentary on "Graphite and its hidden superconductivity"
Authors: Forgan E. M.
Published: December 2013

A Commentary on the paper by P. Esquinazi [Pap. Phys. 5, 050007 (2013)]. The author of the paper offers a Reply.Received: 10 October 2013,, Accepted: 4 November 2013; Edited by: S. A. Grigera; DOI: http://dx.doi.org/10.4279/PIP.050008
Analysis of particle size distribution changes between three measurement sites in northern Scandinavia
Authors: Väänänen R. , Kyrö E.-M. , Nieminen T. , Kivekäs N. , Junninen H. , Virkkula A. , Dal Maso M. , Lihavainen H. , Viisanen Y. , Svenningsson B. , Holst T. , Arneth A. , Aalto P. P. , Kulmala M. , Kerminen V.-M.
Published: December 2013

Abstract. We investigated atmospheric aerosol particle dynamics in a boreal forest zone in northern Scandinavia. We used aerosol number size distribution data measured with either a differential mobility particle sizer (DMPS) or scanning mobility particle sizer (SMPS) at three stations (Värriö, Pallas and Abisko), and combined these data with the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) air mass trajectory analysis. We compared three approaches: analysis of new particle formation events, investigation of aerosol particle number size distributions during the air mass transport from the ocean to individual stations with different overland transport times, and analysis of changes in aerosol particle number size distributions during the air mass transport from one measurement station to another. Aitken-mode particles were found to have apparent average growth rates of 0.6–0.7 nm h−1 when the air masses traveled over land. Particle growth rates during the new particle formation (NPF) events were 3–6 times higher than the apparent particle growth during the summer period. When comparing aerosol dynamics for different overland transport times between the different stations, no major differences were found, except that in Abisko the NPF events were observed to take place in air masses with shorter overland times than at the other stations. We speculate that this is related to the meteorological differences along the paths of air masses caused by the land surface topology. When comparing air masses traveling in an east-to-west direction with those traveling in a west-to-east direction, clear differences in the aerosol dynamics were seen. Our results suggest that the condensation growth has an important role in aerosol dynamics even when NPF is not evident.
Undisturbed and disturbed above canopy ponderosa pine emissions: PTR-TOF-MS measurements and MEGAN 2.1 model results
Authors: Kaser L. , Karl T. , Guenther A. , Graus M. , Schnitzhofer R. , Turnipseed A. , Fischer L. , Harley P. , Madronich M. , Gochis D. , Keutsch F. N. , Hansel A.
Published: December 2013

Abstract. We present the first eddy covariance flux measurements of volatile organic compounds (VOCs) using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) above a ponderosa pine forest in Colorado, USA. The high mass resolution of the PTR-TOF-MS enabled the identification of chemical sum formulas. During a 30 day measurement period in August and September 2010, 649 different ion mass peaks were detected in the ambient air mass spectrum (including primary ions and mass calibration compounds). Eddy covariance with the vertical wind speed was calculated for all ion mass peaks. On a typical day, 17 ion mass peaks, including protonated parent compounds, their fragments and isotopes as well as VOC-H+-water clusters, showed a significant flux with daytime average emissions above a reliable flux threshold of 0.1 mg compound m−2 h−1. These ion mass peaks could be assigned to seven compound classes. The main flux contributions during daytime (10:00–18:00 LT) are attributed to the sum of 2-methyl-3-buten-2-ol (MBO) and isoprene (50%), methanol (12%), the sum of acetic acid and glycolaldehyde (10%) and the sum of monoterpenes (10%). The total MBO + isoprene flux was composed of 10% isoprene and 90% MBO. There was good agreement between the light- and temperature dependency of the sum of MBO and isoprene observed for this work and those of earlier studies. The above canopy flux measurements of the sum of MBO and isoprene and the sum of monoterpenes were compared to emissions calculated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN 2.1). The best agreement between MEGAN 2.1 and measurements was reached using emission factors determined from site-specific leaf cuvette measurements. While the modeled and measured MBO + isoprene fluxes agree well, the emissions of the sum of monoterpenes is underestimated by MEGAN 2.1. This is expected as some factors impacting monoterpene emissions, such as physical damage of needles and branches due to storms, are not included in MEGAN 2.1. After a severe hailstorm event, 22 ion mass peaks (attributed to six compound classes plus some unknown compounds) showed an elevated flux for the two following days. The sum of monoterpene emissions was 4–23 times higher compared to emissions prior to the hailstorm while MBO emissions remained unchanged. The monoterpene emission (in mg compound m−2) during this measurement period is underestimated by 40% if the effect of this disturbance source is not considered.
The effect of local sources on particle size and chemical composition and their role in aerosol-cloud interactions
Authors: Portin H. , Leskinen A. , Hao L. , Kortelainen A. , Miettinen P. , Jaatinen A. , Laaksonen A. , Lehtinen K. E. J. , Romakkaniemi S. , Komppula M.
Published: December 2013

Abstract. The effects of local pollutant sources and particle chemical composition on aerosol–cloud interactions were investigated by measuring cloud interstitial and total aerosol size distributions, particle chemical composition and hygroscopic growth factors and cloud droplet size distributions on an observation tower, with a special focus on comparing clean air masses with those affected by local sources. The polluted air masses contained more particles than the clean air masses in all size classes, excluding the accumulation mode. This was caused by cloud processing, which was also observed for the polluted air but to a lesser extent. Some, mostly minor, differences in the particle chemical composition between the air masses were observed. The average size and number concentration of activating particles were quite similar for both air masses, producing average droplet populations with only minor distinctions. As a case study, a long cloud event was analyzed in detail regarding emissions from local sources, including a paper mill and a heating plant. Clear differences in the total and accumulation mode particle concentrations, particle hygroscopicity and chemical composition during the cloud event were observed. Particularly, larger particles, higher hygroscopicities and elevated amounts of inorganic constituents, especially SO4, were linked with the pollutant plumes. In the air masses affected by traffic and domestic wood combustion, a bimodal particle hygroscopicity distribution was observed, indicating externally mixed aerosol. The variable conditions during the event had a clear impact on cloud droplet formation.
Delayed responses of an Arctic ecosystem to an extremely dry summer: impacts on net ecosystem exchange and vegetation functioning
Authors: Zona D. , Lipson D. A. , Richards J. H. , Phoenix G. K. , Liljedahl A. K. , Ueyama M. , Sturtevant C. S. , Oechel W. C.
Published: December 2013

Abstract. The importance and mode of action of extreme events on the global carbon budget are inadequately understood. This includes the differential impact of extreme events on various ecosystem components, lag effects, recovery times, and compensatory processes. Summer 2007 in Barrow, Arctic Alaska, experienced unusually high air temperatures (fifth warmest over a 65 yr period) and record low precipitation (lowest over a 65 yr period). These abnormal conditions resulted in strongly reduced net Sphagnum CO2 uptake, but no effect neither on vascular plant development nor on net ecosystem exchange (NEE) from this arctic tundra ecosystem. Gross primary production (GPP) and ecosystem respiration (Reco) were both generally greater during most of this extreme summer. Cumulative ecosystem C uptake in 2007 was similar to the previous summers, showing the capacity of the ecosystem to compensate in its net ecosystem exchange (NEE) despite the impact on other functions and structure such as substantial necrosis of the Sphagnum layer. Surprisingly, the lowest ecosystem C uptake (2005–2009) was observed during the 2008 summer, i.e the year directly following the extremely summer. In 2008, cumulative C uptake was ∼70% lower than prior years. This reduction cannot solely be attributed to mosses, which typically contribute with ∼40% – of the entire ecosystem C uptake. The minimum summer cumulative C uptake in 2008 suggests that the entire ecosystem experienced difficulty readjusting to more typical weather after experiencing exceptionally warm and dry conditions. Importantly, the return to a substantial cumulative C uptake occurred two summers after the extreme event, which suggest a high resilience of this tundra ecosystem. Overall, these results show a highly complex response of the C uptake and its sub-components to atypically dry conditions. The impact of multiple extreme events still awaits further investigation.
Using Moran's I and GIS to study spatial pattern of forest litter carbon density in typical subtropical region, China
Authors: Fu W. J. , Jiang P. K. , Zhou G. M. , Zhao K. L.
Published: December 2013

Abstract. The spatial variation of forest litter carbon (FLC) density in the typical subtropical forests in southeast China was investigated using Moran's I, geostatistics and a geographical information system (GIS). A total of 839 forest litter samples were collected based on a 12 km (South–North) × 6 km (East–West) grid system in Zhejiang Province. Forest litter carbon density values were very variable, ranging from 10.2 kg ha−1 to 8841.3 kg ha−1, with an average of 1786.7 kg ha−1. The aboveground biomass had the strongest positive correlation with FLC density, followed by forest age and elevation. Global Moran's I revealed that FLC density had significant positive spatial autocorrelation. Clear spatial patterns were observed using Local Moran's I. A spherical model was chosen to fit the experimental semivariogram. The moderate "nugget-to-sill" (0.536) value revealed that both natural and anthropogenic factors played a key role in spatial heterogeneity of FLC density. High FLC density values were mainly distributed in northwestern and western part of Zhejiang province, which were related to adopting long-term policy of forest conservation in these areas. While Hang-Jia-Hu (HJH) Plain, Jin-Qu (JQ) basin and coastal areas had low FLC density due to low forest coverage and intensive management of economic forests. These spatial patterns in distribution map were in line with the spatial-cluster map described by local Moran's I. Therefore, Moran's I, combined with geostatistics and GIS could be used to study spatial patterns of environmental variables related to forest ecosystem.
Practical analytical solutions for benchmarking of 2-D and 3-D geodynamic Stokes problems with variable viscosity
Authors: Popov I. Yu. , Lobanov I. S. , Popov S. I. , Popov A. I. , Gerya T. V.
Published: December 2013

Abstract. Geodynamic modeling often involves challenging computations involving solution of Stokes and continuity equations under condition of highly variable viscosity. Based on new analytical approach we developed generalized analytical solutions for 2-D and 3-D incompressible Stokes flows with both linearly and exponentially variable viscosity. We demonstrated how these generalized solutions can be converted into 2-D and 3-D test problems suitable for benchmarking numerical codes aimed at modeling various mantle convection and lithospheric dynamics problems. Main advantage of this new generalized approach is that large variety of benchmark solutions can be generated including relatively complex cases with open model boundaries, non-vertical gravity and variable gradients of viscosity and density fields, which are not parallel to Cartesian axes. Examples of respective 2-D and 3-D MatLab codes are provided with this paper.
Geologia da folha de Santa Rita do Passa Quatro
Authors: Massoli Marcos
Published: December 2013

Os dados ora apresentados constituem a Estratigrafia do Projeto de Levantamento Geológico de Formações Superficiais, em andamento na folha de Santa Rita do Passa Quatro, situada entre os paralelos 21º 30' e 21º 45' e os meridianos 47º 15' e 47º 30', com uma área de aproximadamente 700 km2. Na área em questão, situada na borda oriental da Bacia do Paraná, foram mapeadas e descritas as seguintes unidades geológicas: Formação Tatuí; Formação Estrada Nova; Formação Botucatu + Pirambóia; Formação Serra Geral; Formações Terciárias e Quaternárias.
Contribuição da morfologia dos fósseis para dedução de paleoambientes
Authors: Vieira Percy Corrêa
Published: December 2013

O restos fossilizados dos seres que viveram antes da época atual podem servir para deduções dos ambientes em que esses seres viveram. Estando os organismos adaptados ao modo de vida, deduz-se serem de particular importância as formas anatômicas derivadas dessas adaptações. As formas adaptativas não se transmitem à descendência quando espelham caracteres adquiridos e nesse caso tornam-se particularmente importantes na dedução paleoambiental
Contribuição ao estudo da Formação Caiuá
Authors: Arid Fahad Moysés , Barcha Samir Fellício , Mezzalira Sérgio
Published: December 2013

Através de análise sedimentológica de amostras de perfil de poço semi-artesiano, perfurado na localidade de Marabá Paulista, são apresentados dados sobre a posição estratigráfica da Formação Caiuá, no Sudoeste do Estado de São Paulo. Esses dados revelam passagem gradual entre o Hauro e o Caiuá, sugerindo a ocorrência de uma fáceis basal da Formação Hauro entre eles. As evidências sedimentares obtidas no presente trabalho indicam que a Formação Caiuá está sotoposta à Formação Hauro, com consequência cronoestratigráfica confirmando a idade cretácea pré-Hauru atribuida ao Caiuá.
Sugestões para estudo de captação de água subterrânea no Grupo Bauru, considerações tectônicas
Authors: Vieira Percy Corrêa
Published: December 2013

Este trabalho tem por intuito sugerir novos processos para os estudos de captação de água subterrânea aplicáveis ao Grupo Bauru, o qual é excelente reservatório e cobre cerca de 42% do território do Estado. A área objeto de atenção possui perto de 2950 quilômetros quadrados e situa-se entre os meridianos 49º30' e 50º00' W e aproximadamente os parelelos 20º45' e 21º30' S, pertencendo à margem direita do baixo Rio Tietê. O Grupo Bauru, na região em foco, comporta-se como uma seqüência sedimentar sobrejacente aos derrames de basalto da Formação Serra Geral, os quais só afloram no extremo sudoeste. Na parte sul, já nas baixadas do Tietê, bem como nas calhas dos rios na parte central ocorrem depósitos quaternários restritos e pouco espessos, de quase nula influência no comportamento hidrogeológico global. É proposto neste trabalho que os rios, São José dos Dourados, baixo Tietê, Aguapeí, do Peixe e Santo Anastácio constituem-se em alinhamentos estruturais, o que fica atestado entre outras coisas pelo comportamento da superfície basáltica, que é baixa nas calhas dos rios e alta nos espigões (São José dos Dourados e Tietê, extrapolado para Aguapeí, do Peixe e Santo Anastácio). Conhecidos os dados humanos, climatológicos e técnicos relativos ao estudo de água subterrânea, manipular-se-ão os mapas apresentados de modo a encontrar-se o local para construção do poço tubular que melhor satisfaça às necessidades do interessado, bem como às condições de melhor aproveitamento e preservação dos recursos hídricos subterrâneos.
Storm‐induced changes in coastal geomorphology control estuarine secondary productivity
Authors: Filgueira Ramón , Guyondet Thomas , Comeau Luc A. , Grant Jon
Published: December 2013

Estuarine ecosystems are highly sensitive not only to projected effects of climate change such as ocean warming, acidification, and sea‐level rise but also to the incidence of nor'easter storms and hurricanes. The effects of storms and hurricanes can be extreme, with immediate impact on coastal geomorphology and water circulation, which is integral to estuarine function and consequently to provision of ecosystem services. In this article, we present the results of a natural estuarine‐scale experiment on the effects of changes in coastal geomorphology on hydrodynamics and aquaculture production. A bay in Prince Edward Island, Canada, was altered when a nor'easter storm eroded a second tidal inlet through a barrier island. Previous field and modeling studies allowed a comparison of prestorm and post‐storm circulation, food limitation by cultured mussels, and aquaculture harvest. Dramatic increases in mussel production occurred in the year following the opening of the new inlet. Model studies showed that post‐storm circulation reduced food limitation for cultured mussels, allowing greater growth. Climate change is expected to have severe effects on the delivery of marine ecosystem services to human populations by changing the underlying physical‐biological coupling inherent to their functioning.
A moisture budget perspective of the amount effect
Authors: Moore M. , Kuang Z. , Blossey P. N.
Published: December 2013

A stable water isotopologue‐enabled cloud‐resolving model was used to investigate the cause of the amount effect on the seasonal (or longer) time scales. When the total water (vapor and condensed phase) budget of the precipitating column of air is considered, our results indicate that as convection becomes stronger and the precipitation rate increases, the δD of precipitation (δDp) depends on the isotopic composition of the converged vapor more than that of surface evaporation. Tests with disabled fractionation from rain evaporation demonstrate that this mechanism does not account for the amount effect as has been previously suggested. If the isotopic content of converged vapor is made uniform with height with a value characteristic of surface evaporation, the amount effect largely disappears, further supporting the dominance of converged vapor in changes to the δDp signal with increasing precipitation. δDp values were compared to the water budget term , where P is precipitation and E is evaporation. Results from this comparison support the overall conclusion that moisture convergence is central in determining the value of δDp and the strength of the amount effect in steady state.
Geochemical diversity in first rocks examined by the Curiosity Rover in Gale Crater: Evidence for and significance of an alkali and volatile‐rich igneous source
Authors: Schmidt M. E. , Campbell J. L. , Gellert R. , Perrett G. M. , Treiman A. H. , Blaney D. L. , Olilla A. , Calef F. J. , Edgar L. , Elliott B. E. , Grotzinger J. , Hurowitz J. , King P. L. , Minitti M. E. , Sautter V. , Stack K. , Berger J. A. , Bridges J. C. , Ehlmann B. L. , Forni O. , Leshin L. A. , Lewis K. W. , McLennan S. M. , Ming D. W. , Newsom H. , Pradler I. , Squyres S. W. , Stolper E. M. , Thompson L. , VanBommel S. , Wiens R. C.
Published: December 2013

The first four rocks examined by the Mars Science Laboratory Alpha Particle X‐ray Spectrometer indicate that Curiosity landed in a lithologically diverse region of Mars. These rocks, collectively dubbed the Bradbury assemblage, were studied along an eastward traverse (sols 46–102). Compositions range from Na‐ and Al‐rich mugearite Jake_Matijevic to Fe‐, Mg‐, and Zn‐rich alkali‐rich basalt/hawaiite Bathurst_Inlet and span nearly the entire range in FeO* and MnO of the data sets from previous Martian missions and Martian meteorites. The Bradbury assemblage is also enriched in K and moderately volatile metals (Zn and Ge). These elements do not correlate with Cl or S, suggesting that they are associated with the rocks themselves and not with salt‐rich coatings. Three out of the four Bradbury rocks plot along a line in elemental variation diagrams, suggesting mixing between Al‐rich and Fe‐rich components. ChemCam analyses give insight to their degree of chemical heterogeneity and grain size. Variations in trace elements detected by ChemCam suggest chemical weathering (Li) and concentration in mineral phases (e.g., Rb and Sr in feldspars). We interpret the Bradbury assemblage to be broadly volcanic and/or volcaniclastic, derived either from near the Gale crater rim and transported by the Peace Vallis fan network, or from a local volcanic source within Gale Crater. High Fe and Fe/Mn in Et_Then likely reflect secondary precipitation of Fe3+ oxides as a cement or rind. The K‐rich signature of the Bradbury assemblage, if igneous in origin, may have formed by small degrees of partial melting of metasomatized mantle.
U.S. Government shutdown degrades aviation radiation monitoring during solar radiation storm
Authors: Tobiska W. Kent , Gersey Brad , Wilkins Richard , Mertens Chris , Atwell William , Bailey Justin
Published: December 2013

The U.S. Government shutdown from 1 to 17 October 2013 significantly affected U.S. and global aviation radiation monitoring. The closure occurred just as a S2 radiation storm was in progress with an average dose rate of 20 μSv h‐1. We estimate that during the radiation event period, one‐half million passengers were flying in the affected zone and, of this population, four would have received sufficient dose to contract fatal cancer in their lifetimes. The radiation environment can be treated like any other risk‐prone weather event, e.g., rain, snow, icing, clear air turbulence, convective weather, or volcanic ash, and should be made available to flight crews in a timely way across the entire air traffic management system. The shutdown highlighted the need for active operational monitoring of the global radiation environment. Aviation radiation risk mitigation steps are simple and straightforward, i.e., fly at a lower altitude and/or use a more equatorward route. Public tools and media methods are also needed from the space weather scientific and operational communities to provide this information in a timely and accessible manner to the flying public.