bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rethinking the polar cap: Eccentric dipole structuring of ULF power at the highest corrected geomagnetic latitudes
Authors: Urban Kevin D. , Gerrard Andrew J. , Lanzerotti Louis J. , Weatherwax Allan T. 
Published: August 2016

AbstractThe day‐to‐day evolution and statistical features of Pc3‐Pc7 band ultralow frequency (ULF) power throughout the southern polar cap suggest that the corrected geomagnetic (CGM) coordinates do not adequately organize the observed hydromagnetic spatial structure. It is shown that that the local‐time distribution of ULF power at sites along CGM latitudinal parallels exhibit fundamental differences and that the CGM latitude of a site in general is not indicative of the site's projection into the magnetosphere. Thus, ULF characteristics observed at a single site in the polar cap cannot be freely generalized to other sites of similar CGM latitude but separated in magnetic local time, and the inadequacy of CGM coordinates in the polar cap has implications for conjugacy/mapping studies in general. In seeking alternative, observationally motivated systems of “polar cap latitudes,” it is found that eccentric dipole (ED) coordinates have several strengths in organizing the hydromagnetic spatial structure in the polar cap region. ED latitudes appear to better classify the local‐time ULF power in both magnitude and morphology and better differentiate the “deep polar cap” (where the ULF power is largely UT dependent and nearly free of local‐time structure) from the “peripheral polar cap” (where near‐magnetic noon pulsations dominate at lower and lower frequencies as one increases in ED latitude). Eccentric local time is shown to better align the local‐time profiles in the magnetic east component over several PcX bands but worsen in the magnetic north component. It is suggested that a hybrid ED‐CGM coordinate system might capture the strengths of both CGM and ED coordinates. It is shown that the local‐time morphology of median ULF power at high‐latitude sites is dominantly driven by where they project into the magnetosphere, which is best quantified by their proximity to the low‐altitude cusp on the dayside (which is not necessarily quantified by a site's CGM latitude), and that variations in the local‐time morphology at sites similar in ED latitude are due to both geographic local‐time control (relative amplification or dampening by the diurnal variation in the local ionospheric conductivity) and geomagnetic coastal effects (enhanced power in a coastally mediated direction). Regardless of cause, it is emphasized that the application of CGM latitudes in the polar cap region is not entirely meaningful and likely should be dispensed with in favor of a scheme that is in better accord with the observed hydromagnetic spatial structure.
Survey of pickup ion signatures in the vicinity of Titan using CAPS/IMS
Authors: Regoli L. H. , Coates A. J. , Thomsen M. F. , Jones G. H. , Roussos E. , Waite J. H. , Krupp N. , Cox G. 
Published: August 2016

AbstractPickup ion detection at Titan is challenging because ion cyclotron waves are rarely detected in the vicinity of the moon. In this work, signatures left by freshly produced pickup heavy ions (m/q ∼ 16 to m/q ∼ 28) as detected in the plasma data by the Cassini Plasma Spectrometer/Ion Mass Spectrometer (CAPS/IMS) instrument on board Cassini are analyzed. In order to discern whether these correspond to ions of exospheric origin, one of the flybys during which the reported signatures were observed is investigated in detail. For this purpose, ion composition data from time‐of‐flight measurements and test particle simulations to constrain the ions' origin are used. After being validated, the detection method is applied to all the flybys for which the CAPS/IMS instrument gathered valid data, constraining the region around the moon where the signatures are observed. The results reveal an escape region located in the anti‐Saturn direction as expected from the nominal corotation electric field direction. These findings provide new constraints for the area of freshly produced pickup ion escape, giving an approximate escape rate of
ions· s−1.
Observations and simulations of midlatitude ionospheric and thermospheric response to the January 2013 stratospheric sudden warming event
Authors: Wu Qian , Maute A. , Yudin V. , Goncharenko L. , Noto J. , Kerr R. , Jacobi Christoph 
Published: August 2016

AbstractUsing observations from midlatitudes, we examine the ionospheric and thermospheric responses to the 2013 stratospheric sudden warming event by comparing data with four simulations performed by the Whole Atmosphere Community Climate Model eXtended (WACCM‐X), Thermosphere‐Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM), and Thermosphere‐Ionosphere Electrodynamics General Circulation Model (TIEGCM). The WACCM‐X simulation was nudged by the GEOS‐5 data. The two TIMEGCM simulations were nudged by the Modern‐Era Retrospective analysis for Research and Applications data and by the aforementioned WACCM‐X outputs, respectively. The standard TIEGCM simulation was also performed. These four simulations were compared with Millstone Hill (42.6°N, 71.4°W) incoherent scatter radar data, Millstone Hill and Boulder (40.1°N, 105.2°W) upper and lower thermospheric wind data. The meteor radar data from Collm (51.3°N, 13°E) were also used to examine the zonal wave number of the semidiurnal tide (SD). We evaluate the model simulations of the mesospheric and thermospheric responses to the 2013 SSW. The TIMEGCM simulation nudged with the WACCM‐X output has suitable stratospheric input and ionospheric dynamics and can reproduce a sharp rise of hmf2 on January 12 observed by the Millstone Hill radar. The comparison of different models with the lower thermospheric SD tide yielded mixed results. The SD tide maintained mostly as a migrating tide for most of the time and matched the TIEGCM simulation very well. The WACCM‐X appeared to perform better when the observed SD tide displays the large phase shift. It also has larger and more variable SD tide amplitude. The two TIMEGCM simulations have smaller SD amplitudes in general. Observations showed complex SD tide patterns after 20 January, which was difficult to characterize as a migrating tidal mode.
Resolution of rupture directivity in weak events: 1‐D versus 2‐D source parameterizations for the 2011, Mw 4.6 and 5.2 Lorca earthquakes, Spain
Authors: López‐Comino J. A. , Stich D. , Morales J. , Ferreira A. M. G. 
Published: August 2016

AbstractResolving robust source parameters of small‐moderate magnitude earthquakes is still a challenge in seismology. We infer directivity from apparent source time functions (ASTFs) at regional distance and quantify the associated uncertainties. ASTFs are used for (i) modeling a propagating 1‐D line source from the duration data and (ii) inverting the 2‐D slip distribution from the full signals. Slip inversion is performed through a Popperian scheme, where random trial models are either falsified on account of large misfit, or else become members of the solution set of the inverse problem. We assess the resolution of rupture directivity representing centroid shifts from the solution set in a rose diagram. Using as example an event with well‐studied rupture directivity, the 2011 Mw 5.2 Lorca (Spain) earthquake, 1‐D and 2‐D parameterizations yield similar estimates for direction (N213°E and N220°E, respectively) and asymmetry (67:33, 65:35) of rupture propagation, as well as rupture length (2.1 km, 2.7 km) and speed (3.5 km/s, 3.25 km/s). The high rupture velocity ≥ 90% vS may be held primarily responsible for the strong directivity effect of this earthquake. We show that inversion of apparent source durations is intrinsically unable to resolve highly asymmetric bilateral ruptures, while inversion of full ASTFs misses part of the signal's complexity, suggesting the presence of deconvolution artifacts. We extend the analysis to the Mw 4.6 foreshock of the Lorca earthquake, inferring similar directivity parameters and slip pattern as for the mainshock. The rupture toward SW of both earthquakes suggests that this direction could be inherent to the fault segment.
Sensitivity of net thermal flux to the abundance of trace gases in the lower atmosphere of Venus
Authors: Lee Yeon Joo , Sagawa Hideo , Haus Rainer , Stefani Stefania , Imamura Takeshi , Titov Dmitrij V. , Piccioni Giuseppe 
Published: August 2016

AbstractWe calculated the net thermal flux in the atmosphere of Venus from the surface to 100 km altitude. Our atmospheric model was carefully constructed especially for altitudes below the clouds (<48 km), using recent CO2 absorption data. It includes updated collision‐induced absorptions in the <250 cm−1, 1200–1500 cm−1, and 2650–3130 cm−1 wave number ranges. We studied sensitivity of the net thermal flux below the clouds on the abundances of trace gases that were varied within the range reported by observations. Our results reveal a considerable effect of trace gases on radiative budget. We successfully simulate net thermal flux profiles measured in situ by the Night and North probes of Pioneer Venus using 20–50 ppmv H2O, suggesting that the high H2O abundance of 200 ppmv derived in the earlier analysis is not required. Our sensitivity study shows that the trace gases SO2, H2O, and OCS are effective thermal agents, while CO and HCl influences are rather weak. We suggest that the influence of the former three gases should be taken into account to estimate the net radiative energy in the deep atmosphere.
Morphology modulation of gas‐foamed, micrometric, hollow polystyrene particles
Authors: Contaldi Vincenzo , Imperato Luigi , Orsi Silvia , Di Maio Ernesto , Netti Paolo Antonio , Iannace Salvatore 
Published: August 2016

ABSTRACTIn this article, we reports the effects of the processing conditions on the morphological and hollow attributes of polystyrene micrometric hollow particles produced by the use of a recently developed technique based on the gas foaming of spherical, dense particles. By modulating the foaming temperature and saturation pressure, we produced hollow particles with different attributes in terms of hollow dimensions, eccentricity, and open–close features. The results from these small systems were compared, and we found agreement with what is typically observed in bulk polymeric foaming, for example, an increase in the foaming efficiency with saturation pressure and the nonmonotonic effect of temperature. Furthermore, we observed an increase in the hollow number when using nucleating agents with respect to the neat polymer and when using nitrogen with respect to carbon dioxide as the blowing agent. The effects of particle manipulation before foaming to achieve hollow elongated or distorted particles are also reported. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44236.
Evaluation of mechanical properties of Al2O3 and TiO2 nano filled enhanced glass fiber reinforced polymer composites
Authors: Nayak Ramesh Kumar , Mahato K. K. , Routara B. C. , Ray Bankim Chandra 
Published: August 2016

ABSTRACTThe present investigation has emphasized the implication of nano fillers (Al2O3 and TiO2) combined additions in glass fiber reinforced polymer composite on the variation of interlaminar shear strength (ILSS). The experiment has also investigated the effect of crosshead speed during testing and subsequent fracture surface analysis to find out the possible failure modes by scanning electron micrograph examinations. Loss and storage modulus have been experimentally evaluated to support the new findings in the present experimental design. It has been observed that the concurrent presence of nano Al2O3 and TiO2 fillers improves the ILSS. Dynamic mechanical thermal analysis indicated that, the addition of nano fillers reduces the storage and loss modulus of the composites. However, glass transition temperature has not been altered by the nano fillers addition. Box–Behnken design of experiment of surface response methodology has been adopted to optimize the filler content and crosshead speed. A second order mathematical model has been developed and the predicted optimum input parameters are 0.3 wt % Al2O3, 0.15 wt %TiO2, and 500 mm/min crosshead speed. Furthermore, the model predicted results are compared with experimental one and found a close agreement between them. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44274.
Utilization of tall oil to enhance natural fibers for composite applications and production of a bioplastic
Authors: George Michael , Mussone Paolo G. , Bressler David C. 
Published: August 2016

ABSTRACTTall oil is one of the side products from the kraft pulping process of lignocellulosic material. The most abundant acid found in this crude viscous material is abietic acid. Strangely, in the past, the utilization of tall oil has been limited to incineration for cogeneration of power. In this study, tall oil rosin acids (TORAs) were used in two different applications. First, it was used to enhance the hydrophobicity and thermal properties of hemp fibers. Second, TORAs were used to supplement epoxy for the production of a polymeric material. The reaction conditions from a model study were mimicked using a crude tall oil rosin acid mixture to enhance hemp fibers. Treated hemp fibers were characterized with increased surface hydrophobicity and improved thermal properties. Also, IR and X‐ray photoelectron spectroscopy confirmed successful chemical modification and grafting of carbon rich moieties onto the surface of the fibers, respectively. Furthermore, TORAs were used to supplement epoxy resin and produced plastics with comparable properties to pure epoxy based plastics. Specifically, 25% (w/w) replacement exhibited little difference in thermal stability and curing when compared to virgin epoxy plastics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44327.
Real‐time monitoring and control of the load phase of a protein A capture step
Authors: Rüdt Matthias , Brestrich Nina , Rolinger Laura , Hubbuch Jürgen 
Published: August 2016

ABSTRACTThe load phase in preparative Protein A capture steps is commonly not controlled in real‐time. The load volume is generally based on an offline quantification of the monoclonal antibody (mAb) prior to loading and on a conservative column capacity determined by resin‐life time studies. While this results in a reduced productivity in batch mode, the bottleneck of suitable real‐time analytics has to be overcome in order to enable continuous mAb purification. In this study, Partial Least Squares Regression (PLS) modeling on UV/Vis absorption spectra was applied to quantify mAb in the effluent of a Protein A capture step during the load phase. A PLS model based on several breakthrough curves with variable mAb titers in the HCCF was successfully calibrated. The PLS model predicted the mAb concentrations in the effluent of a validation experiment with a root mean square error (RMSE) of 0.06 mg/mL. The information was applied to automatically terminate the load phase, when a product breakthrough of 1.5 mg/mL was reached. In a second part of the study, the sensitivity of the method was further increased by only considering small mAb concentrations in the calibration and by subtracting an impurity background signal. The resulting PLS model exhibited a RMSE of prediction of 0.01 mg/mL and was successfully applied to terminate the load phase, when a product breakthrough of 0.15 mg/mL was achieved. The proposed method has hence potential for the real‐time monitoring and control of capture steps at large scale production. This might enhance the resin capacity utilization, eliminate time‐consuming offline analytics, and contribute to the realization of continuous processing. Biotechnol. Bioeng. 2017;114: 368–373. © 2016 The Authors. Biotechnology and Bioengineering published by Wiley Periodicals, Inc.
Non‐chromatographic bioprocess engineering of a recombinant mineralizing protein for the synthesis of silica nanocapsules
Authors: Wibowo David , Yang Guang‐Ze , Middelberg Anton P.J. , Zhao Chun‐Xia 
Published: August 2016

ABSTRACTInspired by nature, synthetic mineralizing proteins have been developed to synthesize various structures of silica‐based nanomaterials under environmentally friendly conditions. However, the development of bioprocesses able to assist in the translation of these new materials has lagged the development of the materials themselves. The development of cost‐effective and scalable bioprocesses which minimize reliance on chromatography to recover biomolecules from microbial cell factories remains a significant challenge. This paper reports a simplified purification process for a recently reported recombinant catalytic modular (D4S2) protein (M(DPSMKQLADS‐LHQLARQ‐VSRLEHA)4EPSRKKRKKRKKRKKGGGY; M 13.3 kDa; pI 10.9), which combines a variant of the established designer biosurfactant protein DAMP4 with a new biomimetic sequence (RKKRKKRKKRKKGGGY), providing for a bi‐modular functionality (emulsification and biosilicification). The four‐helix bundle structure of the protein has been demonstrated to remain stable and soluble under high temperature and high salt conditions, which confers simplified bioprocessing character. However, the high positive charge on the biosilification sequence necessitates removal of DNA contaminants from crude cell‐extract at an early stage in the process by adding poly(ethyleneimine) (PEI). In this process, cellular protein contaminants were selectively precipitated by adding Na2SO4 to the protein mixture up to a high concentration (1 M) and mixed at high temperature (90°C, 5 min) where D4S2 remained stable and soluble due to its four‐helix bundle structure. Further increase of the Na2SO4 concentration to 1.8 M precipitated, thus separated, D4S2 from residual PEI. The overall yield of the protein D4S2 was 28.8 mg per 800 mL cells (final cultivation OD600 ∼2) which gives an approximate 79% D4S2‐protein yield. In comparison with the previously reported chromatographic purification of D4S2 protein (Wibowo et al., 2015), the final yield of D4S2 protein is increased fourfold in this study. The bio‐produced protein D4S2 was proved to retain it emulsification and biosilicification functionalities enabling the formation of oil‐core silica‐shell nanocapsules at near‐neutral pH and room temperature without the use of any toxic organic solvents, confirming no adverse effects due to bioprocess simplification. This work demonstrates that, through proper bioprocess engineering including the removal of critical contaminants such as DNA, a more efficient, simple, and scalable purification process can be used for the high‐yield bio‐production of a recombinant templating protein useful in the synthesis of bio‐inspired nanomaterials. This simplified process is expected to be easily adapted to recover other mineralizing helix bundle‐based functional proteins from microbial cell factories. Biotechnol. Bioeng. 2017;114: 335–343. © 2016 Wiley Periodicals, Inc.
Constructing “quantized quorums” to guide emergent phenotypes through quorum quenching capsules
Authors: Zargar Amin , Quan David N. , Abutaleb Nadia , Choi Erica , Terrell Jessica L. , Payne Gregory F. , Bentley William E. 
Published: August 2016

ABSTRACTMicrobial cells have for many years been engineered to facilitate
efficient production of biologics, chemicals, and other compounds. As
the “metabolic” burden of synthetic genetic components can impair cell performance, microbial consortia are being developed to piece together specialized subpopulations that collectively produce desired products. Their use, however, has been limited by the inability to control their composition and function. One approach to leverage advantages of the division of labor within consortia is to link microbial subpopulations together through quorum sensing (QS) molecules. Previously, we directed the assembly of “quantized quorums,” microbial subpopulations that are parsed through QS activation, by the exogenous addition of QS signal molecules to QS synthase mutants. In this work, we develop a more facile and general platform for creating “quantized quorums.” Moreover, the methodology is not restricted to QS‐mutant populations. We constructed quorum quenching capsules that partition QS‐mediated phenotypes into discrete subpopulations. This compartmentalization guides QS subpopulations in a dose‐dependent manner, parsing cell populations into activated or deactivated groups. The capsular “devices” consist of polyelectrolyte alginate–chitosan beads that encapsulate high‐efficiency (HE) “controller cells” that, in turn, provide rapid uptake of the QS signal molecule AI‐2 from culture fluids. In this methodology, instead of adding AI‐2 to parse QS‐mutants into subpopulations, we engineered cells to encapsulate them into compartments, and they serve to deplete AI‐2 from wild‐type populations. These encapsulated bacteria therefore, provide orthogonal control of population composition while allowing only minimal interaction with the product‐producing cell population or consortia. We envision that compartmentalized control of QS should have applications in both metabolic engineering and human disease. Biotechnol. Bioeng. 2017;114: 407–415. © 2016 Wiley Periodicals, Inc.
Enhanced itaconic acid production by self‐assembly of two biosynthetic enzymes in Escherichia coli
Authors: Yang Zhongwei , Gao Xin , Xie Hui , Wang Fengqing , Ren Yuhong , Wei Dongzhi 
Published: August 2016

ABSTRACTHere, we described a novel strategy for the production of itaconic acid in Escherichia coli by self‐assembly of aconitase (ACO) and cis‐aconitate decarboxylase (CAD) existing in the metabolic pathway of itaconic acid via the protein–peptide interactions of PDZ domain and PDZ ligand. Co‐expression of ACO and CAD in E. coli (uCA) resulted in low levels of itaconate (117.25 mg/L) after 48 h fermentation while the itaconate titre was significantly improved up to 222.15 mg/L by self‐assembly of ACO‐PDZ (APd) and CAD‐PDZlig (CPl) in E. coli (sPP) under the same conditions. To further confirm the effect of self‐assembly, the itaconate catalyzed from sodium citrate was determined. The sPP was extra efficacious in the early catalytic period, showing approximately threefold itaconate yields increased after 2 h catalysis, when compared to uCA. Furthermore, the itaconate production of sPP was increased from 5 to 8.7 g/L after 30 h of reaction compared to uCA. This self‐assembly strategy showed remarkable potential for the further improvement of itaconate production. Biotechnol. Bioeng. 2017;114: 457–462. © 2016 Wiley Periodicals, Inc.