bluuebunny/crossref_metadata_2025 huggingface dataset:
Recrystallization of AZ31 Alloy
Authors: Tunca Bensu , Aşık Emin Erkan , Nakaş G. Ipek , Bor Şakir
Published: May 2014

Magnesium alloys are extensively used in electronics, automotive and aerospace industries due to their low densities and high specific strengths. However, limited deformability of magnesium alloys at room temperature restricts the applications. Grain refinement and texture weakening as a result of recrystallization can be used to enhance the deformability of these alloys. In this study, recrystallization behavior of cold rolled and swaged AZ31 alloy is investigated at different temperatures in the range of 200-300°C. Effects of unidirectional and complex deformation modes on recrystallization behavior and microstructure development are studied. Microstructural analyses consisted of the examination of the grain structure and twinned regions by using optical and scanning electron microscopes. The volume fraction of recrystallized grains is determined by image analysis and supported by the hardness measurements.
Improved Paint Baking Response of a Novel Al-Mg-Si Alloy Automotive Body Panels by Adding Zn Element and Pre-Ageing Matching
Authors: Li Zhi Hui , Yan Li Zhen , Zhang Yong An , Li Xi Wu , Wang Feng , Li Hong Wei , Xiong Bai Qing
Published: May 2014

In the present work, the microstructure and properties of a novel Al-0.92Mg-0.78Si alloy with adding Zn element were investigated by electron back scattering diffraction (EBSD), transmission electron microscopy (TEM), high transmission electron microscopy (HREM), mechanical properties tests and Erichsen test. The alloy sheet was cold-rolled to about 1mm, then solution treated at 545 °C for 30mins, and immediately water quenched. After solution treatment, the alloy was pre-aged at 140 °C for 10mins. The average grain size of the alloy was about 20μm. The yield stress and elongation of pre-aged alloy was 137MPa and 30% respectively. The IE value of the alloy was 8.6mm. After paint baking at 170 °C for 30mins, the increment of yield stress was about 100MPa. The GP(II) zones were formed in the alloy during paint baking process through adding Zn element, which should play a very important role for improving paint hardening response significantly. GP(II) zones and η ́ phases were formed after artificial ageing at 170 °C for 10h.
Twin Roll Casting (TRC) of Magnesium Alloys – Opportunities and Challenges
Authors: Wells Mary A. , Hadadzadeh Amir
Published: May 2014

Twin Roll Casting (TRC) has been successfully employed for the past sixty years to produce aluminum, steel and, in the past ten years, magnesium sheet. Although the TRC process is relatively simple, its application for commercial-scale magnesium strip production has proven difficult. This is primarily due to inherent characteristics of magnesium alloys, such as their high reactivity to oxygen, low specific heat and latent heat of fusion, and large freezing ranges, which can induce formation of casting defects if various TRC processing parameters, such as metal delivery design, heat transfer in the roll gap, and casting speed, aren’t tightly controlled. Research is underway worldwide to concurrently gain a better understanding of TRC processing variables in order to provide optimum casting conditions which will reduce defects, and develop new magnesium alloys with properties tailored to the TRC process. The opportunities and challenges associated with magnesium TRC will be outlined and include: 1) defect formation during TRC of magnesium alloy AZ31, 2) the feasibility of producing clad magnesium strip via TRC and 3) the effect of scale-up (moving from a laboratory unit to commercial production) will have on the TRC process for magnesium.
Effect of Al Addition on Phase Constitution and Heat Treatment Behavior in Ti-8.5mass%Mn-1mass%Fe-Al Alloys
Authors: Ikeda Masahiko , Ueda Masato , Sumi Yoshinori , Niinomi Mitsuo
Published: May 2014

Titanium is considered to be a ubiquitous element since it has the 9th-highest Clarke number of all elements. Iron and manganese can also be used as beta stabilizers for Ti alloys, and can be considered to be ubiquitous because of their 4th- and 11th-highest Clarke numbers, respectively. However, investigations into the behavior of Ti-Mn-Fe alloys during heat treatment have shown that in some alloys, the isothermal omega phase is precipitated. Because this phase can lead to brittleness, it is very important to prevent it from forming. It is well known that aluminum can suppress the precipitation of the isothermal omega phase. Thus, in the present study, we investigated the effect of Al content on the phase constitution and heat-treatment behavior of Ti-8.5mass%Mn-1mass%Fe-0 to 4.5mass%Al alloys using electrical resistivity, Vickers hardness, and X-ray diffraction measurements. In all solution-treated and quenched alloys, only the beta phase was identified, thus confirming the suppression of omega-phase precipitation. The resistivity was found to increase monotonically with Al content, while the Vickers hardness decreased up to 3 mass% Al and then remained constant.
Effect of Multipass Welding Using a Low Transformation Temperature Filler Metal on Residual Stress and Toughness
Authors: Abreu H.F.G. , Tavares W.S. , de Miranda Hélio Cordeiro , Cindra Fonseca Maria P. , Virgens-Neto H.N. , Béreš M.
Published: May 2014

Residual stresses in welded components are consequence of stress and/or thermal gradients and influenced by factors such as joint geometry, variation in strength of the material, preheat temperature, heat input, post-weld heat treatment and phase transformation strains. During the 70’s, it was observed that the level of residual stress accumulated in a constrained sample during cooling from austenite could be reduced after transformation to martensite or bainite. Some works have evaluated effect of welding using a low transformation temperature martensitic filler metal on the level of residual stress in single pass joints. According to these studies, martensite start temperature in the range 200–250°C can be extremely effective for mitigation of tensile residual stresses. The outcome of most of these works was on one hand increase of fatigue life due to the mitigation of tensile residual stresses via transformation strains, on the other a significant reduction of the fracture toughness.In the present study, sections of API 5L class B steel tubes were multipass welded using a 12Cr-5Ni low transformation temperature filler metal in addition to a conventional filler metal. Residual stresses in the inner and outer surfaces were measured by X-ray diffraction. Aspects related to the improvement of toughness in the weld metal due to the tempering of one pass by the subsequent were also discussed.
Development of Ultrafine Grained Austenitic Stainless Steels by Large Strain Deformation and Annealing
Authors: Belyakov Andrey , Kipelova Alla , Odnobokova Marina , Shakhova Iaroslava , Kaibyshev Rustam
Published: May 2014

The development of ultrafine grained structures in 316L and 304-type austenitic stainless steels subjected to large strain cold working and subsequent annealing and their effect on mechanical properties were studied. The cold rolling was accompanied by a mechanical twinning and a partial martensitic transformation and resulted in the development of elongated austenite/ferrite grains with the transverse size of about 50 nm at a strain of 4. The grain refinement by large strain cold working resulted in an increase of tensile strength above 2000 MPa in the both steels. Annealing at temperatures above 500°C resulted in ferrite-austenite reversion. However, the transverse grain/subgrain size remained on the level of about 100-150 nm after annealing at temperatures up to 700°C.
Thermo-Mechanically Controlled Processed Ultrahigh Strength Steels
Authors: Chatterjee Subrata , Ghosh S.K. , Bandyopadhyay P.S.
Published: May 2014

A low-carbon, titanium and niobium (Ti-Nb) bearing and a low-carbon titanium, niobium and copper (Ti-Nb-Cu) bearing ultra high strength steel have been thermo-mechanically processed on a laboratory scale unit. Evolution of microstructure and mechanical properties of the above air cooled steels have been studied at different finish rolling temperatures (FRTs). Microstructural characterization reveals largely a mixture of granular bainite and bainitic ferrite along with the precipitation of microalloying carbide/carbonitride particles and/or Cu-rich precipitates. (Ti-Nb) bearing steel yields higher yield strength (1114-1143 MPa) along with higher tensile strength (1591-1688 MPa) and moderate ductility (12-13%) as compared to (Ti-Nb-Cu) bearing steel having yield strength (934-996 MPa) combined with tensile strength (1434-1464 MPa) and similar ductility (13%) for the selected range of 850-750°C FRT. Due to higher strength-ductility combinations, these present investigated steels can be regarded as the replacement material for ballistic applications as well as other sectors like defense, pipeline, cars, pressure vessels, ships, offshore platforms, aircraft undercarriages and rocket motor casings etc.
Key words: Thermo-mechanical controlled processing, ultra high strength steel, microstructure, mechanical properties.
The Mechanism of Martensite-Austenite Microconstituents Formation during Thermomechanical Controlling Processing in Low Carbon Bainitic Steel
Authors: Liang Xiao Jun , Hua Ming Jian , DeArdo Anthony J.
Published: May 2014

Bainite or the mixture of bainite and martensite is required to reach high strength levels in low carbon high strength steel. However, the bainite reaction rarely goes to completion, resulting in mixed structures of predominately bainitic ferrite and minor amounts of retained austenite, cementite or martensite mainly located at the ferrite grain boundaries. The exact nature of this minor transformation product depends on several factors including bulk composition, segregation and cooling rate. When the minor phase is largely martensite, the non-bainitic microstructure is called martensite-austenite microconstituent or MA. Interestingly, MA is believed to be one of the main factors causing the deterioration of toughness of steels. MA is also often associated with hydrogen-related cracking. In this current study, the formation of martensite-austenite constituents was studied experimentally and the results analyzed theoretically.
Two-Step Quenching & Partitioning of 42SiCrB Steel
Authors: Grosse-Heilmann Niko , Zylla Isabella Maria , Kozeschnik Ernst , Peters Andreas
Published: May 2014

In recent years, Quenching and Partitioning (Q&P) became an interesting thermal process route for semi-finished high strength low alloyed steel components. Recent publications demonstrate promising mechanical properties with considerable ductility enhancement. To assess the potential of the two-step Q&P heat treatment in seamless tube production, corresponding tests are carried out on 42SiCrB steel (0.42wt% C, 2.0wt% Si, 1.3wt.% Cr, 0.6wt.% Mn, 0.002wt.% B). Feasible Q&P heat treatment process parameters are identified using the Constrained-Carbon-Equilibrium (CCE) model, carbon diffusion calculations and isothermal TTT curves with previous quenching. Furthermore achieved volume fraction of retained austenite is analyzed by XRD experiments.
Microstructure-Mechanical Properties Relationships for Complex Microstructures in High Strength Steels
Authors: Iza-Mendia Amaia , Gutiérrez Isabel
Published: May 2014

Due to the increased complexity of steel microstructures, when considering the application of available Hall-Petch type equations for yield strength prediction, a number of difficulties raises. For example, the correlation between grain size measurements by EBSD technique and optical microscopy (OP) in complex microstructures is required in order to integrate data to the traditional equations developed for OP results and ferrite-pearlite microstructures. Besides, the introduction of some additional terms to the equations to account for precipitation, C in solution and forest dislocation contributions presents some difficulties that need to be overcome to improve prediction accuracy.
Different microstructures (ferrite-pearlite, bainite, quenched and Q&T) have been produced by thermal and thermomechanical treatments, followed by microstructural characterisation and mechanical testing. A Hall-Petch coefficient dependent on the boundary misorientation distribution is proposed. This approach allows dealing in a similar way ferritic, bainitic and martensitic microstructures. The Hall-Petch coefficient, thus defined, corresponds to the previously proposed by Pickering for ferrite, while bainitic microstructures give a smaller value. Additionally, the equation used to express the fracture appearance transition temperature of ferritic-pearlitic microstructure has been generalized from the developments made in the calculation of the yield stress.
Dilatometer Analysis of the One Step Quenching and Partitioning Process in a 1.5%Si Steel
Authors: Martin David , Eliasson Johan , Brolund Bengt , Granbom Ylva
Published: May 2014

A one step quenching and partitioning process was applied to a 0.2%C-2.0%Mn-0.5%Cr-1.5%Si steel by quenching austenitised samples to several different temperatures below the experimentallydetermined martensite start temperature of 397 °C and isothermally partitioning them beforequenching to room temperature using a quenching deformation dilatometer. These treatmentsyielded predominantly martensitic microstructures containing 5.6 vol.% to 7.5 vol.% retained austenite,as measured by x-ray diffraction. In each treatment, strong dilation was recorded during isothermalpartitioning, with little indication of phase transformation during subsequent cooling to room temperature.This behaviour lends weight to the idea that an isothermal phase transformation occurred duringpartitioning, and that the final microstructure is a mixture of athermally and isothermally formed constituents.These results also suggest that the final microstructure of this steel is mostly formed beforeand during partitioning.
Diffusion Bonding of Duplex Stainless Steel and Ti Alloy with and without Interlayer
Authors: Chatterjee Subrata , Kundu S. , Sam S. , Mishra B.
Published: May 2014

In the present study, the microstructure and strength properties of diffusion bonded joints of duplex stainless steel (SS) to Ti alloy (TiA) with and without nickel alloy (NiA) as an intermediate material was investigated in the temperature range of 800-950°C for 60 mins in vacuum. In the case of directly bonded stainless steel and titanium alloy, the layer wise σ phase and λ+FeTi phase mixture were observed at the bond interface. However, when nickel alloy was used as an interlayer, the interfaces indicate that Ni3Ti, NiTi and NiTi2 are formed at the nickel alloy-titanium alloy interface and the stainless steel-nickel alloy interface is free from intermetallics up to 875°C and above this temperature, Fe-Ti and Fe-Cr-Ti base intermetallics were formed. The irregular shaped particles have been observed within the Ni3Ti intermetallic layer. The joint tensile and shear strength were measured; a maximum tensile strength of ~519.2MPa and shear strength of ~398.3MPa were obtained for direct bonded joint when processed at 875°C. However, when nickel base alloy was used as an interlayer in the same materials at the bonding temperature of 900°C the bond tensile and shear strength increases to ~596.5MPa and ~434.4MPa, respectively.
Keywords: Diffusion bonding, intermetallic compounds, interlayer, SEM, XRD
Effect of Cold Rolling and Isothermal Holding before Austenitization on Mechanical Properties in Steels
Authors: Konishi Sanae , Nakai Kiyomichi , Sakamoto Tatsuaki , Nakai Keisuke , Kobayashi Sengo
Published: May 2014

Effect of pre-treatments before austenitization on mechanical properties in steels has been investigated. Pre-treatments are cold rolling and isothermal holding below A1 before austenitization. Pre-treatments were performed in order to introduce dislocation network in austenite (γ), which acts as nucleation site for “bainite laths within γ grain (BWING)”. During the pre-treatment of isothermal holding below A1, carbon segregation and/or carbide formation might occur at grain boundary of ferrite (α). Thin γ layer might be formed around the region where carbon segregation and/or carbide formation occurred in the beginning of austenitization. Transformation strain due to α → γ would be effectively relaxed by the deformation of thin γ film, because α had been already hardened by the cold rolling. Dislocations might be introduced dominantly into the thin γ film, and stable dislocation network even in the high temperature region of γ might be formed. BWING nucleates around the dislocation network to relax the strain field around dislocation network. BWING would nucleate also at ( BWING / γ ) interface cooperatively to relax the strain around the interface, resulting in the formation of “aggregate of bainite laths with nearly parallel slip systems between neighboring bainite laths (ALPS)”. Larger ALPS containing a lot of BWINGs might be formed in the pre-treated steel, and improves tensile strength and toughness.
Development of Hot Rolling Schedules for Lean Alloyed Pipeline Steel X80 Produced on Continuous Mill 2000
Authors: Naumov Anton A. , Bezobrazov Yuriy A. , Chernikov Evgenii V.
Published: May 2014

Analysis of standard and experimental lean alloyed chemical composition for pipeline steel X80 was made. Rolling schedules for experimental X80 chemical composition by means of computer simulation using HSMM, AusEvol+ and AusTran software were developed for continuous mill 2000. Developed schedules were analyzed in order to choose one of them which guarantees the required microstructure receiving. The chosen schedule was realized on Gleeble-3800 system by tension-compression tests for experimental chemical composition. Microstructure analysis and mechanical testing of received samples was made to compare results with requirements submitted to pipeline steel X80.
Physical Metallurgy Related to the Thermomechanical Process of Hot Rolling of Nb Microalloyed Steel Beams: Prediction of Mechanical Properties
Authors: Garcia Reis Emanuelle , Barbosa Ronaldo
Published: May 2014

The main physical metallurgy processes controlling final mechanical properties in as hot rolled steel products are basically recrystalization, grain growth, precipitation and austenite to ferrite phase transformation. Knowledge of how these processes interact during an industry hot rolling schedule is the key to understand how to obtain certain mechanical properties. This know how has been routinely applied to the manufacturing of flat products such as plates and strips. Less has been reported for non flat products. When even there are such reports, these usually do not present any comparison between predictions and industry real data. This paper addresses the case of rolling of structural beams at an industry trial. Emphasis is put on how the final mechanical properties were obtained and how they can be predicted. An ordinary microstructure model was used and then the predictions were checked by comparing them to industry data. After validation, suggestions were made for improvements in the schedule aiming at having superior mechanical properties at the end product. Austenite grain size evolution is important in defining final properties, as expected. The presence of Nb as microalloyed element can enhance such properties and its role to this particular industry process was discussed.
Modern and Cenozoic records of magnesium behaviour from foraminiferal Mg isotopes
Authors: Pogge von Strandmann P. A. E. , Forshaw J. , Schmidt D. N.
Published: May 2014

Abstract. Magnesium is an element critically involved in the carbon cycle, because weathering of Ca–Mg silicates removes atmospheric CO2 into rivers, and formation of Ca–Mg carbonates in the oceans removes carbon from the ocean–atmosphere system. Hence the Mg cycle holds the potential to provide valuable insights into Cenozoic climate-system history, and the shift during this time from a greenhouse to icehouse state. We present Mg isotope ratios for the past 40 Myr using planktic foraminifers as an archive. Modern foraminifera, which discriminate against elemental and isotopically heavy Mg during calcification, show no correlation between the Mg isotope composition (δ26Mg) and temperature, Mg / Ca or other parameters such as carbonate saturation (Δ CO3). However, inter-species isotopic differences imply that only well-calibrated single species should be used for reconstruction of past seawater. Seawater δ26Mg inferred from the foraminiferal record decreased from ~ 0‰ at 15 Ma, to −0.83‰ at the present day, which coincides with increases in seawater lithium and oxygen isotope ratios. It strongly suggests that neither Mg concentrations nor isotope ratios are at steady-state in modern oceans, given its ~ 10 Myr residence time. From these data, we have developed a dynamic box model to understand and constrain changes in Mg sources to the oceans (rivers) and Mg sinks (dolomitisation and hydrothermal alteration). Our estimates of seawater Mg concentrations through time are similar to those independently determined by pore waters and fluid inclusions. Modelling suggests that dolomite formation and the riverine Mg flux are the primary controls on the δ26Mg of seawater, while hydrothermal Mg removal and the δ26Mg of rivers are more minor controls. Using riverine flux and isotope ratios inferred from the 87Sr / 86Sr record, the modelled Mg removal by dolomite formation shows minima in the Oligocene and at the present day (with decreasing trends from 15 Ma), both coinciding with rapid decreases in global temperatures.
Trend analysis using non-stationary time series clustering based on the finite element method
Authors: Gorji Sefidmazgi M. , Sayemuzzaman M. , Homaifar A. , Jha M. K. , Liess S.
Published: May 2014

Abstract. In order to analyze low-frequency variability of climate, it is useful to model the climatic time series with multiple linear trends and locate the times of significant changes. In this paper, we have used non-stationary time series clustering to find change points in the trends. Clustering in a multi-dimensional non-stationary time series is challenging, since the problem is mathematically ill-posed. Clustering based on the finite element method (FEM) is one of the methods that can analyze multidimensional time series. One important attribute of this method is that it is not dependent on any statistical assumption and does not need local stationarity in the time series. In this paper, it is shown how the FEM-clustering method can be used to locate change points in the trend of temperature time series from in situ observations. This method is applied to the temperature time series of North Carolina (NC) and the results represent region-specific climate variability despite higher frequency harmonics in climatic time series. Next, we investigated the relationship between the climatic indices with the clusters/trends detected based on this clustering method. It appears that the natural variability of climate change in NC during 1950–2009 can be explained mostly by AMO and solar activity.
Owner Experiences in Treating Dogs and Cats Diagnosed With Diabetes Mellitus in the United StatesS
Authors: Aptekmann Karina P. , Armstrong Jane , Coradini Marcia , Rand Jacquie
Published: May 2014

The objective of this study was to report owner experiences and satisfaction in treating a pet with diabetes mellitus using a descriptive report from an Internet-based survey. Descriptive analysis of results was performed, χ2 tests were used to detect differences in responses between dog and cat owners, and correlations were assessed using the nonparametric Spearman rank correlation. A total of 834 owners participated in the survey. More diabetic dogs (97%) than cats (82%) were treated with insulin injections. Insulin was administered twice daily in 87% of dogs and 73% of cats. Porcine lente and neutral protamine Hagedorn were the most commonly administered insulins in dogs. In cats, glargine and protamine zinc insulin were the most commonly used insulins. Most pets were not fed a prescribed diabetes diet. More cat (66%) than dog (50%) owners were satisfied with the diabetic control achieved. Cat owners were more likely to use home blood glucose monitoring. Treatment was considered expensive by the majority of owners. Few published reports follow diabetic pets after diagnosis or report owner satisfaction. The results of this study provide useful information that may help veterinarians better educate owners and set expectations regarding diabetes treatment and quality of life for diabetic pets.
Directed Differentiation of Human Induced Pluripotent Stem Cells Toward Bone and Cartilage: In Vitro Versus In Vivo Assays
Authors: Phillips Matthew D. , Kuznetsov Sergei A. , Cherman Natasha , Park Kyeyoon , Chen Kevin G. , McClendon Britney N. , Hamilton Rebecca S. , McKay Ronald D.G. , Chenoweth Josh G. , Mallon Barbara S. , Robey Pamela G.
Published: May 2014

The ability to differentiate induced pluripotent stem cells (iPSCs) into committed skeletal progenitors could allow for an unlimited autologous supply of such cells for therapeutic uses; therefore, we attempted to create novel bone-forming cells from human iPSCs using lines from two distinct tissue sources and methods of differentiation that we previously devised for osteogenic differentiation of human embryonic stem cells, and as suggested by other publications. The resulting cells were assayed using in vitro methods, and the results were compared with those obtained from in vivo transplantation assays. Our results show that true bone was formed in vivo by derivatives of several iPSC lines, but that the successful cell lines and differentiation methodologies were not predicted by the results of the in vitro assays. In addition, bone was formed equally well from iPSCs originating from skin or bone marrow stromal cells (also known as bone marrow-derived mesenchymal stem cells), suggesting that the iPSCs did not retain a “memory” of their previous life. Furthermore, one of the iPSC-derived cell lines formed verifiable cartilage in vivo, which likewise was not predicted by in vitro assays.
Employeurs démarquez-vous ! La marque employeur, un gisement de valeur inexploité ?
Authors: Viot Catherine , Benraïss-Noailles Laïla
Published: May 2014

Cet article propose une revue de la littérature consacrée à la marque employeur. Le concept et sa mesure font tout d’abord l’objet d’une présentation et d’une discussion. Une définition est proposée avant que les antécédents de la marque employeur ne soient exposés. Les effets de la marque employeur sur les employés actuels et potentiels sont ensuite discutés. Enfin, notre état de l’art débouche sur un modèle intégrateur des effets internes et externes de la marque employeur. A la suite de ce modèle, un programme de recherche, destiné à combler les zones peu ou pas explorées à ce jour, est proposé.
miR-142 orchestrates a network of actin cytoskeleton regulators during megakaryopoiesis
Authors: Chapnik Elik , Rivkin Natalia , Mildner Alexander , Beck Gilad , Pasvolsky Ronit , Metzl-Raz Eyal , Birger Yehudit , Amir Gail , Tirosh Itay , Porat Ziv , Israel Liron L , Lellouche Emmanuel , Michaeli Shulamit , Lellouche Jean-Paul M , Izraeli Shai , Jung Steffen , Hornstein Eran
Published: May 2014

Genome-encoded microRNAs (miRNAs) provide a posttranscriptional regulatory layer that controls the differentiation and function of various cellular systems, including hematopoietic cells. miR-142 is one of the most prevalently expressed miRNAs within the hematopoietic lineage. To address the in vivo functions of miR-142, we utilized a novel reporter and a loss-of-function mouse allele that we have recently generated. In this study, we show that miR-142 is broadly expressed in the adult hematopoietic system. Our data further reveal that miR-142 is critical for megakaryopoiesis. Genetic ablation of miR-142 caused impaired megakaryocyte maturation, inhibition of polyploidization, abnormal proplatelet formation, and thrombocytopenia. Finally, we characterized a network of miR-142-3p targets which collectively control actin filament homeostasis, thereby ensuring proper execution of actin-dependent proplatelet formation. Our study reveals a pivotal role for miR-142 activity in megakaryocyte maturation and function, and demonstrates a critical contribution of a single miRNA in orchestrating cytoskeletal dynamics and normal hemostasis.
Global‐scale ionospheric flow and aurora precursors of auroral substorms: Coordinated SuperDARN and IMAGE/WIC observations
Authors: Shi Yong , Zesta Eftyhia
Published: May 2014

We use global‐scale polar cap flow vector measurements from the Super Dual Auroral Radar Network (SuperDARN) with the concurrent auroral observations from the Wideband Imaging Camera on board Imager for Magnetopause‐to‐Aurora Global Exploration (IMAGE/WIC) to study the polar cap flow and auroral precursors during a substorm onset on 26 December 2000. We show, for the first time, close connection between the dayside and nightside polar cap flow enhancements (with the enhanced dayside flow preceding the nightside one by several minutes) and the ensuing poleward boundary intensification (PBI)/streamer, and the later onset, forming a complete preonset sequence for a substorm onset. Our results supplement our previous study by providing further evidence that the dayside polar cap flow disturbance may be the key to initiate the whole process of a certain type of substorm by triggering reconnection somewhere in the tail via applied field (or flow) perturbations on the nightside plasma sheet boundary layer. Our results also indicate that a preexisting double oval structure is likely a favorable precondition for a certain type of substorm to be triggered by polar cap flow disturbance and the associated PBIs/streamers. On the other hand, not all our global‐scale preonset auroral sequences support the recent revised onset scenario proposed by Nishimura et al. () using the all‐sky imagers of the Time History of Events and Macroscale Interactions during Substorms mission. This suggests that the preceding PBI/streamer is not a sufficient condition to trigger a substorm. It may not even be a necessary condition considering the existence of various types of substorm onsets.
On the solar cycle variation of the winter anomaly
Authors: Burns A. G. , Wang W. , Qian L. , Solomon S. C. , Zhang Y. , Paxton L. J. , Yue X.
Published: May 2014

Constellation Observing System for Meteorology, Ionosphere and Climate, Ionosonde, and Global Ultraviolet Imager data have been used to investigate the solar cycle changes in the winter anomaly (the winter anomaly is defined as the enhancement of the F2 peak electron density in the winter hemisphere over that in the summer hemisphere) in the last solar cycle. There is no winter anomaly in solar minimum, and an enhancement of about 50% in winter over summer ones on the same day of the year at solar maximum. This solar cycle variation in the winter anomaly is primarily due to greater winter to summer differences of [O]/[N2] in solar maximum than in solar minimum, with a secondary contribution from the effects of temperature on the recombination coefficient between O+ and the molecular neutral gas. The greater winter increases in electron density in the Northern Hemisphere than in the Southern Hemisphere appear to be related to the greater annual variation of [O]/[N2] in the north than in the south.
In Situ Electrical Characterization of Anatase TiO2 Quantum Dots
Authors: Engel Johanna , Bishop Sean R. , Vayssieres Lionel , Tuller Harry L.
Published: May 2014

A novel method for performing in situ characterization of the electrical properties of pristine, ultrafine nanopowders is reported. A modified dilatometer, with a spring‐loaded push rod and electrodes, allows for the simultaneous monitoring of the packed nanopowder's lateral displacement as well as its complex impedance spectroscopy as a function of temperature within a controlled environment. Anatase TiO2 quantum dots of 2 nm diameter, on average, are examined and found to simultaneously shrink and become more resistive upon initial heating. The resistance changes by approximately 3 orders of magnitude upon heating, associated with the desorption of adsorbed water, demonstrating the need for sample preconditioning. Subsequent electrical resistivity measurements, as a function of oxygen partial pressure, over approximately 40 orders of magnitude, at temperatures between 300 °C and 400 °C, exhibit nearly 9 orders of magnitude change in conductivity. The data are consistent with a Frenkel‐based defect disorder model characterized by an enthalpy of reduction of 5.5 ± 0.5 eV.
Seroprevalence of autoantibodies against brain antigens in health and disease
Authors: Dahm Liane , Ott Christoph , Steiner Johann , Stepniak Beata , Teegen Bianca , Saschenbrecker Sandra , Hammer Christian , Borowski Kathrin , Begemann Martin , Lemke Sandra , Rentzsch Kristin , Probst Christian , Martens Henrik , Wienands Jürgen , Spalletta Gianfranco , Weissenborn Karin , Stöcker Winfried , Ehrenreich Hannelore
Published: May 2014

Objective

We previously reported an unexpectedly high seroprevalence (∼10%) of N‐methyl‐D‐aspartate‐receptor subunit‐NR1 (NMDAR1) autoantibodies (AB) in healthy and neuropsychiatrically ill subjects (N = 2,817). This finding challenges an unambiguous causal relationship of serum AB with brain disease. To test whether similar results would be obtained for other brain antigen‐directed AB previously connected with pathological conditions, we systematically screened serum samples of 4,236 individuals.

Methods

Serum samples of healthy (n = 1,703) versus neuropsychiatrically ill subjects (schizophrenia, affective disorders, stroke, Parkinson disease, amyotrophic lateral sclerosis, personality disorder; total n = 2,533) were tested. For analysis based on indirect immunofluorescence, we used biochip mosaics of frozen brain sections (rat, monkey) and transfected HEK293 cells expressing respective recombinant target antigens.

Results

Seroprevalence of all screened AB was comparable in healthy and ill individuals. None of them, however, reached the abundance of NMDAR1 AB (again ∼10%; immunoglobulin [Ig] G ∼1%). Appreciable frequency was noted for AB against amphiphysin (2.0%), ARHGAP26 (1.3%), CASPR2 (0.9%), MOG (0.8%), GAD65 (0.5%), Ma2 (0.5%), Yo (0.4%), and Ma1 (0.4%), with titers and Ig class distribution similar among groups. All other AB were found in ≤0.1% of individuals (anti–AMPAR‐1/2, AQP4, CV2, Tr/DNER, DPPX‐IF1, GABAR‐B1/B2, GAD67, GLRA1b, GRM1, GRM5, Hu, LGl1, recoverin, Ri, ZIC4). The predominant Ig class depended on antigen location, with intracellular epitopes predisposing to IgG (chi‐square = 218.91, p = 2.8 × 10−48).

Interpretation

To conclude, the brain antigen‐directed AB tested here are comparably detectable in healthy subjects and the disease groups studied here, thus questioning an upfront pathological role of these serum AB. Ann Neurol 2014;76:82–94
Unlocking the N2 Selectivity of Benzotriazoles: Regiodivergent and Highly Selective Coupling of Benzotriazoles with Allenes
Authors: Xu Kun , Thieme Niels , Breit Bernhard
Published: May 2014

The rhodium‐catalyzed, highly N2‐ and N1‐selective coupling of benzotriazoles with allenes is reported. The exceptionally high N2 and N1 selectivities were achieved by using a rhodium(I)/DPEphos and rhodium(I)/JoSPOphos catalyst, respectively. This method permits the atom‐economic synthesis of valuable branched N2‐ and N1‐allylated benzotriazole derivatives and allows for preliminary studies of their reactivity.
Thiopeptide Engineering: A Multidisciplinary Effort towards Future Drugs
Authors: Just‐Baringo Xavier , Albericio Fernando , Álvarez Mercedes
Published: May 2014

The recent development of thiopeptide analogues of antibiotics has allowed some of the limitations inherent to these naturally occurring substances to be overcome. Chemical synthesis, semisynthetic derivatization, and engineering of the biosynthetic pathway have independently led to complementary modifications of various thiopeptides. Some of the new substances have displayed improved profiles, not only as antibiotics, but also as antiplasmodial and anticancer drugs. The design of novel molecules based on the thiopeptide scaffold appears to be the only strategy to exploit the high potential they have shown in vitro. Herein we present the most relevant achievements in the production of thiopeptide analogues and also discuss the way the different approaches might be combined in a multidisciplinary strategy to produce more sophisticated structures.
High electrical conductivity of nylon 6 composites obtained with hybrid multiwalled carbon nanotube/carbon fiber fillers
Authors: Zhu Xiang‐Dong , Zang Chong‐Guang , Jiao Qing‐Jie
Published: May 2014

The synergetic effect of multiwalled carbon nanotubes (MWNTs) and carbon fibers (CFs) in enhancing the electrical conductivity of nylon 6 (PA6) composites was investigated. To improve the compatibility between the fillers and the PA6 resin, we grafted γ‐aminopropyltriethoxy silane (KH‐550) onto the MWNTs and CFs after carboxyl groups were generated on their surface by chemical oxidation with nitric acid. Fourier transform infrared spectroscopy and thermogravimetric analysis proved that the KH‐550 molecules were successfully grafted onto the surface of the MWNTs and CFs. Scanning electron microscopy and optical microscopy showed that the obtained modified fillers reduced the aggregation of fillers and resulted in better dispersion and interfacial compatibility. We found that the electrical percolation threshold of the MWNT/PA6 and CF/PA6 composites occurred when the volume fraction of the fillers were 4 and 5%, respectively. The MWNT/CF hybrid‐filler system exhibited a remarkable synergetic effect on the electrically conductive networks. The MWNT/7% CF hybrid‐filler system appeared to show a second percolation when the MWNT volume fraction was above 4% and a volume resistivity reduction of two orders of magnitude compared with the MWNT/PA6 system. The mechanical properties of different types of PA6 composites with variation in the filler volume content were also studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40923.
The influence of the operational environment on efficiency of international airports
Authors: Marques Rui Cunha , Simões Pedro , Carvalho Pedro
Published: May 2014

Heterogeneity must be considered in the efficiency analysis of decision‐making units; otherwise, the results will be strongly biased. This is also valid for airport management where the operational environment heavily influences efficiency. In this paper, conditional efficiency measures are applied to airports to incorporate heterogeneity in non‐parametric frontier models which are robust for outlying observations. In particular, the influence of the operational environment on airport efficiency is examined in a sample of 141 international airports. The conclusions show that the operational environment indeed matters and that privatisation, regulation, traffic transfer and the dominant carrier have a positive effect on efficiency, whereas aeronautical revenues influence it negatively. Copyright © 2014 John Wiley & Sons, Ltd.
Metabolite profiles of epimedin C in rat plasma and bile by ultra‐performance liquid chromatography coupled with quadrupole‐TOF‐MS
Authors: Cui Li , Sun E. , Zhang Zhenhai , Tan Xiaobin , Xu Fengjuan , Jia Xiaobin
Published: May 2014

Epimedin C is one of the major bioactive constituents of Herba Epimedii. In this study, the metabolite profiles of epimedin C in rat plasma and bile were qualitatively investigated, and the possible metabolic pathways of epimedin C were subsequently proposed. After oral administration of epimedin C at a single dose of 80 mg/kg, rat biological samples were collected and pretreated by protein precipitation. Then these pretreated samples were injected into an Acquity UPLC BEH C18 column and detected by ultra‐performance liquid chromatography/quadrupole‐time‐of‐flight mass spectrometry. In all, 12 metabolites were identified in the biosamples. Of these, eight, two from plasma and six from bile, are, to our knowledge, reported here for the first time. The results indicated that epimedin C was metabolized via desugarization, dehydrogenation, hydrogenation, dehydroxylation, hydroxylation, demethylation and glucuronidation pathways in vivo. Thus, this study revealed the possible metabolite profiles of epimedin C in rat plasma and bile. Copyright © 2014 John Wiley & Sons, Ltd.
Bioavailability comparison of a new form of vilazodone XVII to IV in beagles using liquid chromatography/mass spectrometry
Authors: Zeng Ling‐ling , Sun Li‐li , Zou Qiaogen , Zhou Fan , Wei Ping , Ouyang Ping‐kai
Published: May 2014

Vilazodone hydrochloride (CAS 163521‐12‐8) is polymorphic and has 15 crystal forms, referred to as I–XI and XIII–XVI. In the study, we prepared and performed structural identification of a new crystal form named XVII. To investigate this in vivo, a rapid and sensitive method based on liquid–liquid extraction, followed by high‐performance liquid chromatography–tandem mass spectrometry (HPLC‐MS/MS) was developed and validated for the determination of vilazodone hydrochloride in dog plasma. This HPLC‐MS/MS method was successfully applied to a bioavailability comparison of two crystal forms of vilazodone hydrochloride (IV and XVII) in six healthy beagles using a single‐dose, two‐way crossover design. The maximum plasma concentration (Cmax), the time taken to reach Cmax, and the area under the concentration–time curve were determined following oral administration of 10 mg vilazodone hydrochloride (IV or XVII) to beagles. These analyses revealed no significant bioavailability differences between vilazodone hydrochloride forms IV and XVII in dogs. Copyright © 2014 John Wiley & Sons, Ltd.
Assistant agents to advice users in hybrid structured 3D virtual environments
Authors: Almajano Pablo , Lopez‐Sanchez Maite , Rodriguez Inmaculada , Trescak Tomas
Published: May 2014

Hybrid structured 3D Virtual Environments model serious activities in immersive 3D spaces, where participants are human and software agents, and their interactions are regulated by an Organization Centered Multi‐Agent System (OCMAS). In this context, both OCMAS social model and the tasks that users need to accomplish can be rather complex, and thus, users may benefit from having an assistance service. Hence, we propose personal assistant agents (PA), which, based on knowledge about the OCMAS specification and current system state, provide the user with an advice (a plan) to achieve her or his goal. Additionally, we implement this service with PLAN-EA, an Extension of the A *  algorithm that generates plans for a user whose actions may depend on other users’ actions. Thus, PAs provide plans that do not only include assisted user actions but also other users’ ones. We illustrate our approach by means of v‐mWater—an online water market—and make a comparative analysis, with and without assistance, where efficiency—in terms of number of user actions—shows an improvement (7 vs 10.8), efficacy—percentage of completed tasks—also improves (93% vs 77%), and assistance's overall satisfaction is positive. Copyright © 2014 John Wiley & Sons, Ltd.
Nickel–Copper/Gadolinium‐Doped Ceria (CGO) Composite Electrocatalyst as a Protective Layer for a Solid‐Oxide Fuel Cell Anode Fed with Ethanol
Authors: Lo Faro Massimiliano , Reis Rafael M. , Saglietti Guilherme G. A. , Sato Andre G. , Ticianelli Edson A. , Zignani Sabrina C. , Aricò Antonio S.
Published: May 2014

A nickel–copper alloy is prepared by using the oxalate method and subsequent in situ reduction. The bimetallic alloy is mixed with gadolinium‐doped ceria (CGO) to obtain a composite material with mixed electronic–ionic conductivity. The catalytic and electrocatalytic properties of the composite material for ethanol conversion are described. Different conditions to simulate bio‐ethanol feed operation are selected. Electrochemical tests are performed by utilizing the NiCu/CGO cermet as a barrier layer in a conventional anode‐supported solid‐oxide fuel cell (AS‐SOFC). A comparative study between the modified cell and a conventional AS‐SOFC without the protective layer is made. A maximum power density of 277 mW cm−2@0.63 V is recorded in the presence of a mixture of ethanol–water for a cell containing the protective anodic layer compared with 231 mW cm−2@0.64 V for a bare cell under the same conditions. This corresponds to a 20 % increase in performance.
Zincocene and Dizincocene N‐Heterocyclic Carbene Complexes and Catalytic Hydrogenation of Imines and Ketones
Authors: Jochmann Phillip , Stephan Douglas W.
Published: May 2014

The N‐heterocyclic carbene (NHC) adducts Zn(CpR)2(NHC)] (CpR=C5HMe4, C5H4SiMe3; NHC=ItBu, IDipp (Dipp=2,6‐diisopropylphenyl), IMes (Mes=mesityl), SIMes) were prepared and shown to be active catalysts for the hydrogenation of imines, whereas decamethylzincocene [ZnCp*2] is highly active for the hydrogenation of ketones in the presence of noncoordinating NHCs. The abnormal carbene complex [Zn(OCHPh2)2(aItBu)]2 was formed from spontaneous rearrangement of the ItBu ligand during incomplete hydrogenation of benzophenone. Two isolated ZnI adducts [Zn2Cp*2(NHC)] (NHC=ItBu, SIMes) are presented and characterized as weak adducts on the basis of 13C NMR spectroscopic and X‐ray diffraction experiments. A mechanistic proposal for the reduction of [ZnCp*2] with H2 to give [Zn2Cp*2] is discussed.
Retrograde intraciliary trafficking of opsin during the maintenance of cone‐shaped photoreceptor outer segments of Xenopus laevis
Authors: Tian Guilian , Lodowski Kerrie H. , Lee Richard , Imanishi Yoshikazu
Published: May 2014

Photoreceptor outer segments (OSs) are essential for our visual perception, and take either rod or cone forms. The cell biological basis for the formation of rods is well established; however, the mechanism of cone formation is ill characterized. While Xenopus rods are called rods, they exhibit cone‐shaped OSs during the early process of development. To visualize the dynamic reorganization of disk membranes, opsin and peripherin/rds were fused to a fluorescent protein, Dendra2, and expressed in early developing rod photoreceptors, in which OSs are still cone‐shaped. Dendra2 is a fluorescent protein which can be converted from green to red irreversibly, and thus allows spatiotemporal labeling of proteins. Using a photoconversion technique, we found that disk membranes are assembled at the base of cone‐shaped OSs. After incorporation into disks, however, Opsin‐Dendra2 was also trafficked from old to new disk membranes, consistent with the hypothesis that retrograde trafficking of membrane components contributes to the larger disk membrane observed toward the base of the cone‐shaped OS. Such retrograde trafficking is cargo‐specific and was not observed for peripherin/rds‐Dendra2. The trafficking is unlikely mediated by diffusion, since the disk membranes have a closed configuration, as evidenced by CNGA1 labeling of the plasma membrane. Consistent with retrograde trafficking, the axoneme, which potentially mediates retrograde intraflagellar trafficking, runs through the entire axis of OSs. This study provides an insight into the role of membrane reorganization in developing photoreceptor OSs, and proves that retrograde trafficking of membrane cargoes can occur there. J. Comp. Neurol. 522:3577–3589, 2014. © 2014 Wiley Periodicals, Inc.