bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variations of the 3‐D coronal magnetic field associated with the X3.4‐class solar flare event of AR 10930
Authors: He Han , Wang Huaning , Yan Yihua , Chen P. F. , Fang Cheng 
Published: April 2014

AbstractThe variations of the 3‐D coronal magnetic fields associated with the X3.4‐class flare of active region 10930 are studied in this paper. The coronal magnetic field data are reconstructed from the photospheric vector magnetograms obtained by the Hinode satellite and using the nonlinear force‐free field extrapolation method developed in our previous work (He et al., 2011). The 3‐D force‐free factor α, 3‐D current density, and 3‐D magnetic energy density are employed to analyze the coronal data. The distributions of α and current density reveal a prominent magnetic connectivity with strong negative α values and strong current density before the flare. This magnetic connectivity extends along the main polarity inversion line and is found to be totally broken after the flare. The distribution variation of magnetic energy density reveals the redistribution of magnetic energy before and after the flare. In the lower space of the modeling volume the increase of magnetic energy dominates, and in the higher space the decrease of energy dominates. The comparison with the flare onset imaging observation exhibits that the breaking site of the magnetic connectivity and site with the highest values of energy density increase coincide with the location of flare initial eruption. We conclude that a cramped positive α region appearing in the photosphere causes the breaking of the magnetic connectivity. A scenario for flare initial eruption is proposed in which the Lorentz force acting on the isolated electric current at the magnetic connectivity breaking site lifts the associated plasmas and causes the initial ejection.
Moisture recycling in the Iberian Peninsula from a regional climate simulation: Spatiotemporal analysis and impact on the precipitation regime
Authors: Rios‐Entenza Alexandre , Soares Pedro M. M. , Trigo Ricardo M. , Cardoso Rita M. , Miguez‐Macho Gonzalo 
Published: April 2014

AbstractThe contribution of the evapotranspiration from a certain region to the precipitation over the same area is referred to as water recycling. In this paper, we explore the spatiotemporal links between the recycling mechanism and the Iberian rainfall regime. We use a 9 km resolution Weather Research and Forecasting simulation of 18 years (1990–2007) to compute local and regional recycling ratios over Iberia, at the monthly scale, through both an analytical and a numerical recycling model. In contrast to coastal areas, the interior of Iberia experiences a relative maximum of precipitation in spring, suggesting a prominent role of land‐atmosphere interactions on the inland precipitation regime during this period of the year. Local recycling ratios are the highest in spring and early summer, coinciding with those areas where this spring peak of rainfall represents the absolute maximum in the annual cycle. This confirms that recycling processes are crucial to explain the Iberian spring precipitation, particularly over the eastern and northeastern sectors. Average monthly recycling values range from 0.04 in December to 0.14 in June according to the numerical model and from 0.03 in December to 0.07 in May according to the analytical procedure. Our analysis shows that the highest values of recycling are limited by the coexistence of two necessary mechanisms: (1) the availability of sufficient soil moisture and (2) the occurrence of appropriate synoptic configurations favoring the development of convective regimes. The analyzed surplus of rainfall in spring has a critical impact on agriculture over large semiarid regions of the interior of Iberia.
Parameter optimization, sensitivity, and uncertainty analysis of an ecosystem model at a forest flux tower site in the United States
Authors: Wu Yiping , Liu Shuguang , Huang Zhihong , Yan Wende 
Published: April 2014

AbstractEcosystem models are useful tools for understanding ecological processes and for sustainable management of resources. In biogeochemical field, numerical models have been widely used for investigating carbon dynamics under global changes from site to regional and global scales. However, it is still challenging to optimize parameters and estimate parameterization uncertainty for complex process‐based models such as the Erosion Deposition Carbon Model (EDCM), a modified version of CENTURY, that consider carbon, water, and nutrient cycles of ecosystems. This study was designed to conduct the parameter identifiability, optimization, sensitivity, and uncertainty analysis of EDCM using our developed EDCM‐Auto, which incorporated a comprehensive R package—Flexible Modeling Framework (FME) and the Shuffled Complex Evolution (SCE) algorithm. Using a forest flux tower site as a case study, we implemented a comprehensive modeling analysis involving nine parameters and four target variables (carbon and water fluxes) with their corresponding measurements based on the eddy covariance technique. The local sensitivity analysis shows that the plant production‐related parameters (e.g., PPDF1 and PRDX) are most sensitive to the model cost function. Both SCE and FME are comparable and performed well in deriving the optimal parameter set with satisfactory simulations of target variables. Global sensitivity and uncertainty analysis indicate that the parameter uncertainty and the resulting output uncertainty can be quantified, and that the magnitude of parameter‐uncertainty effects depends on variables and seasons. This study also demonstrates that using the cutting‐edge R functions such as FME can be feasible and attractive for conducting comprehensive parameter analysis for ecosystem modeling.
Natural biogeochemical cycle of mercury in a global three‐dimensional ocean tracer model
Authors: Zhang Yanxu , Jaeglé Lyatt , Thompson LuAnne 
Published: April 2014

AbstractWe implement mercury (Hg) biogeochemistry in the offline global 3‐D ocean tracer model (OFFTRAC) to investigate the natural Hg cycle, prior to any anthropogenic input. The simulation includes three Hg tracers: dissolved elemental (Hg0aq), dissolved divalent (HgIIaq), and particle‐bound mercury (HgPaq). Our Hg parameterization takes into account redox chemistry in ocean waters, air‐sea exchange of Hg0, scavenging of HgIIaq onto sinking particles, and resupply of HgIIaq at depth by remineralization of sinking particles. Atmospheric boundary conditions are provided by a global simulation of the natural atmospheric Hg cycle in the GEOS‐Chem model. In the surface ocean, the OFFTRAC model predicts global mean concentrations of 0.16 pM for total Hg, partitioned as 80% HgIIaq, 14% Hg0aq, and 6% HgPaq. Total Hg concentrations increase to 0.38 pM in the thermocline/intermediate waters (between the mixed layer and 1000 m depth) and 0.82 pM in deep waters (below 1000 m), reflecting removal of Hg from the surface to the subsurface ocean by particle sinking followed by remineralization at depth. Our model predicts that Hg concentrations in the deep North Pacific Ocean (>2000 m) are a factor of 2–3 higher than in the deep North Atlantic Ocean. This is the result of cumulative input of Hg from particle remineralization as deep waters transit from the North Atlantic to the North Pacific on their ~2000 year journey. The model is able to reproduce the relatively uniform concentrations of total Hg observed in the old deep waters of the North Pacific Ocean (observations: 1.2 ± 0.4 pM; model: 1.1 ± 0.04 pM) and Southern Ocean (observations: 1.1 ± 0.2 pM; model: 0.8 ± 0.02 pM). However, the modeled concentrations are factors of 5–6 too low compared to observed concentrations in the surface ocean and in the young water masses of the deep North Atlantic Ocean. This large underestimate for these regions implies a factor of 5–6 anthropogenic enhancement in Hg concentrations.
Biomimetic Metal Phenolates
Authors: Tamasi Gabriella , Cini Renzo 
Published: April 2014

The chapter reports on recent studies of metal complexes that have the phenolate group as a ligand. The synthesis and characterization of many low molecular weight complexes is reviewed and commented on. Special attention is devoted to biomimetic models, for a deeper understanding of metalloprotein structures and functions. The chapter is divided into two parts, related to oxidant and antioxidant activities and to the hydrolysis of phospatediesters, respectively.Activity of phenols as antioxidants and VIVO2+, MnII, MnIII, MnIV,CoII, CoIII, NiII, CuI, CuIIand ZnIIcomplexes with phenolato‐containing Schiff bases as biomimetic for biological systems, is the focus of the first part. A section is dedicated to selected CuIIand PtIIcomplexes having pharmaceutical active molecules as ligands, from the OXICAM family of non‐steroidal anti‐inflammatory drugs. The second part reports on metal–phenolato complexes as models for phosphodiesterase enzymes. Dinuclear complexes based on ZnII, FeIII/ZnII, ZnII/MgIImetal centers are reviewed and commented on
Organic Compounds Containing Bonds between Se or Te with P, As, Sb and Bi
Authors: Murai Toshiaki 
Published: April 2014

AbstractThis chapter describes syntheses, structures, and reactions of the compounds with phosphorus‐selenium double bonds and with at least one carbon‐phosphorus single bond and of their heavier congeners. Among them, phosphane selenides have been the most deeply studied and used as Lewis base catalysts, metal ligands, molecular sensors, and stating materials leading to selenium‐containing nanoparticles. The coupling constants between the phosphorus and selenium atoms are informative on the basicity of the phosphanes. Phosphinoselenoic acid chlorides and secondary phosphanes are frequently used precursors to give a range of phosphinoselenoic acid derivatives, whereas selenation of dichlorophosphanes leads to phosphonoselenoic acid dichlorides, which are converted to a variety of acid derivatives. The selenation of phosphinites also gives phosphinoselenoic acidO‐esters. Stereochemical course of the substitution reaction atP‐chiral phosphorus center in the substitution reaction has been elucidated. Some reactions of dimers of diselenoxophosphanes such as Woollin's reagent are also shown. The chapter finally describes examples of phosphane tellurides, arsenic, antimony, and bismuth isologues of phosphane selenides, although these are fewer.
Reactions of Metal Complexes with Singlet Oxygen
Authors: Selke Matthias 
Published: April 2014

Abstract

A variety of reactions of metal complexes with singlet oxygen have been reported during the past several decades. These reactions can be divided into two parts, that is, reactions of the metal center and ligand oxidations. Reactions at the metal center involve physical deactivation of singlet oxygen and oxidative addition to form metal‐dioxygen complexes. These peroxo complexes may undergo insertion reactions or lose the added dioxygen molecule either in the singlet or triplet state. Reaction of some metal centers with hydrogen peroxide may also lead to formation of singlet oxygen which constitutes a dark (non‐photochemical) method of
1
O
2
generation. Olefinic ligands bound to Sn, Si, and W centers undergo singlet oxygen ene reactions, leading to conventional H‐ene products and/or peroxides bound to the metal atom (metallo‐ene reaction). These peroxides may be useful synthons for further transformations. Examples of [2+2] and [4+2] cycloaddition of singlet oxygen to ligands are also discussed. Finally, singlet oxygen reacts with metal‐bound thiolates and dithiolates, leading to formation of a variety of oxidized sulfur ligands, such as sulfenates and sulfinates. The mechanisms of these reactions appear to be somewhat similar to that of the photooxidation of organic sulfides but many details are poorly understood at this time.
Electrostatic Accelerators
Authors: Weisser David C. 
Published: April 2014

AbstractWe review the types of electrostatic accelerators currently in use and their historical antecedents. Applications enrich many areas of modern research especially in material analysis and modification. The rapidly developing scope of accelerator mass spectrometry, AMS, has given birth to new low energy accelerators and revitalized the appreciation of the enabling physics of the electron stripping process. Another exciting development has been in the simultaneous bombardment by several accelerators to simulate the radiation environment of nuclear reactors. This exploits a wide variety of accelerators and diagnostic techniques. High energy electrostatic accelerators are being eclipsed as injectors to booster accelerators by dedicated positive ion injectors. Nevertheless, electrostatic accelerators continue to be the bedrock for most injector laboratories during the often extended transition to positive ion injectors. They also continue in their historic role as workhorses of nuclear structure physics.
Nuclear γ‐Spectroscopy and the γ‐Spheres
Authors: Riley Mark , Simpson John 
Published: April 2014

Abstract

High‐resolution γ‐ray spectroscopy is one of the most powerful tools to study the structure of atomic nuclei. Significant advances in the development of increasingly sensitive instrumentation have taken place in recent decades. The latest 4π γ‐ray arrays, or “γ‐spheres,” continue to reveal fascinating new scientific phenomena at the limits of isospin, excitation energy, angular momentum, temperature, and charge. Another huge leap forward in the resolving power of
Ge
‐based detection systems is now taking place via the development of γ‐ray tracking arrays, which, when combined with new accelerator developments, assures a most exciting future to this field. These technical advances also have a wide range of application spin‐offs.
Physics of the Neutron
Authors: Schreckenbach Klaus 
Published: April 2014

AbstractThe nuclear and particle physics of the free neutron is described for neutron energies in the range of nanoelectronvolts to megaelectronvolts. The interaction of the neutron with the atomic nucleus, which comprises scattering and absorption, and the reaction mechanism are discussed, including parity nonconserving processes. In neutron particle physics, the progress in neutron sources and neutron beams has yielded experimental results for sensitive tests of the standard model in particle physics and beyond and some key experiments are presented.
Modeling and Bayesian parameter estimation for semibatch pH‐shift reactive crystallization of l‐glutamic acid
Authors: Su Qing‐Lin , Chiu Min‐Sen , Braatz Richard D. 
Published: April 2014

A mathematical model for semibatch pH‐shift reactive crystallization of l‐glutamic acid is developed that takes into account the effects of protonation and deprotonation in the species balance of glutamic acid, crystal size distribution, polymorphic crystallization, and nonideal solution properties. The crystallization mechanisms of α‐ and β‐forms of glutamic acid are addressed by considering primary and secondary nucleation, size‐dependent growth rate, and mixing effects on nucleation. The kinetic parameters are estimated by Bayesian inference from batch experimental data collected from literature. Probability distributions of the estimated parameters in addition to their point estimates are obtained by Markov Chain Monte Carlo simulation. The first‐principles model is observed in good agreement with the experimental data and can be further used for model predictions in robust control strategies. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2828–2838, 2014
Pathologic heterogeneity persists in early active multiple sclerosis lesions
Authors: Metz Imke , Weigand Stephen D. , Popescu Bogdan F. G. , Frischer Josa M. , Parisi Joseph E. , Guo Yong , Lassmann Hans , Brück Wolfgang , Lucchinetti Claudia F. 
Published: April 2014

ObjectiveMultiple sclerosis (MS) lesions demonstrate immunopathological heterogeneity in patterns of demyelination. Previous cross‐sectional studies reported immunopatterns of demyelination were identical among multiple active demyelinating lesions from the same individual, but differed between individuals, leading to the hypothesis of intraindividual pathological homogeneity and interindividual heterogeneity. Other groups suggested a time‐dependent heterogeneity of lesions. The objective of our present study was to analyze tissue samples collected longitudinally to determine whether patterns of demyelination persist over time within a given patient.MethodsArchival tissue samples derived from patients with pathologically confirmed central nervous system inflammatory demyelinating disease who had undergone either diagnostic serial biopsy or biopsy followed by autopsy were analyzed immunohistochemically. The inclusion criteria consisted of the presence of early active demyelinating lesions—required for immunopattern classification—obtained from the same patient at 2 or more time points.ResultsAmong 1,321 surgical biopsies consistent with MS, 22 cases met the study inclusion criteria. Twenty‐one patients (95%) showed a persistence of immunopathological patterns in tissue sampled from different time points. This persistence was demonstrated for all major patterns of demyelination. A single patient showed features suggestive of both pattern II and pattern III on biopsy, but only pattern II among all active lesions examined at autopsy.InterpretationThese findings continue to support the concept of patient‐dependent immunopathological heterogeneity in early MS and suggest that the mechanisms and targets of tissue injury may differ among patient subgroups. These observations have potentially significant implications for individualized therapeutic approaches. Ann Neurol 2014;75:728–738
Monitoring Surface Processes During Heterogeneous Asymmetric Hydrogenation of Ketones on a Chirally Modified Platinum Catalyst by Operando Spectroscopy
Authors: Meemken Fabian , Hungerbühler Konrad , Baiker Alfons 
Published: April 2014

AbstractSurface processes occurring at the catalytic chiral surface of a cinchona‐modified Pt catalyst during the asymmetric hydrogenation of activated ketones have been monitored for the first time using operando ATR‐IR spectroscopy. Fundamental information about this catalytic system could be gained, including the chiral modification process of the catalyst, the surface interaction of reactant ketone with preadsorbed chiral modifier, the role of hydrogen as well as the influence of the product enantiomers in the catalytic cycle. The formation of a diastereomeric transient surface complex between ketone and chiral modifier was found to be related to the ketone consumption. Among the studied activated ketones, a correlation between stereoselection and the strength of the intermolecular hydrogen bond was identified. Dissociated hydrogen from the catalytic surface is found to play a crucial role in the formation of the diastereomeric surface complex.
Acid‐Catalyzed Oxidative Radical Addition of Ketones to Olefins
Authors: Schweitzer‐Chaput Bertrand , Demaerel Joachim , Engler Hauke , Klussmann Martin 
Published: April 2014

AbstractBased on a mechanistic study, we have discovered a Brønsted acid catalyzed formation of ketone radicals. This is believed to proceed via thermally labile alkenyl peroxides formed in situ from ketones and hydroperoxides. The discovery could be utilized to develop a multicomponent radical addition of unactivated ketones and tert‐butyl hydroperoxide to olefins. The resulting γ‐peroxyketones are synthetically useful intermediates that can be further transformed into 1,4‐diketones, homoaldol products, and alkyl ketones. A one‐pot reaction yielding a pharmaceutically active pyrrole is also described.
A molecularly imprinted polymer as artificial receptor for the detection of indole‐3‐carbinol
Authors: Scorrano Sonia , Mergola Lucia , Del Sole Roberta , Lazzoi Maria Rosaria , Vasapollo Giuseppe 
Published: April 2014

ABSTRACTMolecularly imprinting polymer technology is used to prepare a molecularly imprinted polymer (MIP) for the selective recognition of indole‐3‐carbinol (I3C), a chemopreventive and chemotherapeutic phytochemical associated with the anticancer activities of cruciferous vegetables. Prepolymerization study via nuclear magnetic resonance technique is done to choose the best functional monomer that establishes more interaction with the template. The prepared MIP is tested before in batch experiments and subsequently used as solid‐phase extraction sorbent for the selective detection of I3C from standard solutions. In order to verify the selectivity of the MIP, the binding of structurally related compounds, such as indole‐3‐acetonitrile, teophylline, and tryptophan, on the polymer is investigated. The experiments indicate that the MIP is highly selective for I3C with an association constant of Ka = (1.37 ± 0.07) × 103 M−1. Standard mixture solution loaded on MIP‐SPE cartridge give a recovery of 95% for I3C, while the other compounds are totally eluted during washing step. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40819.
Production, optimization, and partial purification of lipase fromPseudomonassp. strainBUP6, a novel rumen bacterium characterized fromMalabari goat
Authors: Priji Prakasan , Unni Kizhakkepowathial Nair , Sajith Sreedharan , Binod Parameswaran , Benjamin Sailas 
Published: April 2014

AbstractThis study introduces a novel bacterium—Pseudomonassp. strainBUP6—isolated from the rumen of theMalabari goat with efficiency for producing lipase. It showed significant production of lipase when grown in a newly designed basal medium, supplemented with vegetable oil. Suitability of five vegetable oils such as groundnut oil, coconut oil, olive oil, sunflower oil, and palm oil as inducer for the production of lipase was examined, and groundnut oil supported the highest production of lipase (96.15 U/mL). Various physical parameters required for the maximum production of lipase were statistically optimized.Plackett–Burmann design was employed to study the interactive effects of physical parameters and found that temperature, agitation, and pH effected the production of lipase significantly. The optimum conditions for lipase production (37 °C, 200 rpm, and pH 6.9) were detected byBox–Behnken design and response surface methodology, which resulted in the 0.3‐fold increase (i.e., 126 U/mL) of the lipase activity over the unoptimized condition. The apparent molecular mass of partially purified lipase was 35 kDa, as judged bySDS‐PAGE; the activity of lipase was also confirmed by nativePAGE. Thus, this study focuses on the need for the exploitation of rumen microbes for the production of industrially significant and human‐friendly biomolecules to meet the future needs.
Exoelectrogenic biofilm as a template for sustainable formation of a catalytic mesoporous structure
Authors: Yates Matthew D. , Cusick Roland D. , Ivanov Ivan , Logan Bruce E. 
Published: April 2014

ABSTRACTMesoporous structures can increase catalytic activity by maximizing the ratio of surface area to volume, but current synthesis techniques utilize expensive polymers and toxic chemicals. A Geobacter sulfurreducens biofilm was used as a sustainable template to form mesoporous Pd structures while eliminating the need for synthetic chemicals. The bulk of the biofilm material was removed by thermal treatments after nanoparticle formation, producing a catalytic Pd mesoporous (pore size 9.7 ± 0.1 nm) structure attached to the graphite electrode with a 1.5–2 µm thick backbone composed of nanoparticles (∼200 nm). A control electrode electrochemically plated with Pd in the absence of a biofilm exhibited a variable planar Pd base (∼0.5–3 µm thick) with sporadic Pd extrusions (∼2 µm across, 1–5 µm tall) from the surface. The biotemplated mesoporous structure produced 15–20% higher stable current densities during H2 oxidation tests than the electrochemically plated control electrode, even though 30% less Pd was present in the biotemplated catalyst. These results indicate that electroactive biofilms can be used as a sustainable base material to produce nanoporous structures without the need for synthetic polymers. Biotechnol. Bioeng. 2014;111: 2349–2354. © 2014 Wiley Periodicals, Inc.