bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow Chemistry – A Key Enabling Technology for (Multistep) Organic Synthesis
Authors: Wegner Jens , Ceylan Sascha , Kirschning Andreas 
Published: January 2012

AbstractLaboratory scaled flow‐through processes have seen an explosive development over the past decade and have become an enabling technology for improving synthetic efficiency through automation and process optimization. Practically, flow devices are a crucial link between bench chemists and process engineers. The present review focuses on two unique aspects of modern flow chemistry where substantial advantages over the corresponding batch processes have become evident. Flow chemistry being one out of several enabling technologies can ideally be combined with other enabling technologies such as energy input. This may be achieved in form of heat to create supercritical conditions. Here, indirect methods such as microwave irradiation and inductive heating have seen widespread applications. Also radiation can efficiently be used to carry out photochemical reactions in a highly practical and scalable manner. A second unique aspect of flow chemistry compared to batch chemistry is associated with the option to carry out multistep synthesis by designing a flow set‐up composed of several flow reactors. Besides their role as chemical reactors these can act as elements for purification or solvent switch.
Direct Asymmetric Aldol Reactions in Water Catalysed by a Highly Active C2‐Symmetrical Bisprolinamide Organocatalyst
Authors: Delaney Joshua P. , Henderson Luke C. 
Published: January 2012

AbstractA novel C2‐symmetrical bisprolinamide organocatalyst was synthesised and used to facilitate asymmetric direct aldol reactions in a water emulsion. Reactions were performed at room temperature with very low catalyst loadings (1–2.5 mol%) without the required use of additives, co‐catalysts or extended reaction times (24 h). This catalyst system was then used with a variety of aldehyde substrates showing good reaction generality for benzaldehydes with cyclohexanone (dr range 77/23 to >99/1, anti/syn; ee range 33% to >99%) and moderate scope with cyclopentanone (dr range 45/55 to 76/24, anti/syn; ee range 14% to 68%). Ultra‐low catalysts loadings (0.1 and 0.05 mol%) were also investigated demonstrating catalyst turnover numbers in the order of 1000.
SIAPhos: Phosphorylated Sulfonimidamides and their Use in Iridium‐Catalyzed Asymmetric Hydrogenations of Sterically Hindered Cyclic Enamides
Authors: Patureau Frederic W. , Worch Christin , Siegler Maxime A. , Spek Anthony L. , Bolm Carsten , Reek Joost N. H. 
Published: January 2012

AbstractPhosphorylated sulfonimidamides (SIAPhos) undergo ion exchange reactions with cationic complexes, [Rh(cod)2BF4] and [Ir(cod)2BarF], or neutral complexes [Rh(cod)Cl]2 and [Ir(cod)Cl]2, leading to unprecedented neutral complexes with P‐N‐S‐N chelates. Use of the resulting neutral iridium complexes in asymmetric hydrogenation reactions of tri‐ and tetrasubstituted enamides leads to products with high enantioselectivities (up to 92% ee).
Impact of particle morphology on surface oxidation of nanoparticles: A kinetic Monte Carlo based study
Authors: Mukherjee Dibyendu , Wang Matthew , Khomami Bamin 
Published: January 2012

AbstractA high‐fidelity coagulation driven kinetic Monte Carlo (KMC) model is developed to study the physics of the nonlinear interplay between competing exothermic collision‐coalescence mediated surface oxidation and complex morphologies in aggregated nanostructures generated during gas‐phase synthesis of nanoparticles. Results suggest a twofold oxidation mechanism in which thermally activated processes form a critical oxide shell, beyond which morphological complexity of nanoparticles gives rise to enhanced oxidation. Simulation results for the example case‐study of Al nanoparticle synthesis in air under different prototypical processing conditions, i.e., temperature, pressure and volume loading, show the efficacy of the model in determining optimal process variables for tuning the structural and chemical makeup of energetic nanomaterials. Finally, it is demonstrated that inclusion of nonisothermal coalescence that leads to the formation of fractal‐like nanoparticles (particularly, < 15 nm) gives rise to higher degrees of oxidation when compared to instantly coalescing spherical particles. © 2012 American Institute of Chemical Engineers AIChE J, 2012
Wet granular flows in a bladed mixer: Experiments and simulations of monodisperse spheres
Authors: Remy Brenda , Khinast Johannes G. , Glasser Benjamin J. 
Published: January 2012

AbstractThe flow and agglomeration of wet particles in a bladed mixer was studied experimentally using particle image velocimetry and computationally using the discrete element method. The experimental and computational work showed that particle beds at low moisture contents are characterized by enhanced convective and diffusive particle motion as well as enhanced mixing kinetics when compared to dry particle beds. This behavior is attributed to the development of small particle agglomerates which behave like rough, nonspherical particles and enable the transfer of energy from the blades to the particle bed. At higher moisture contents, a different behavior was observed. Particle convective and diffusive motion was hindered by the presence of moisture at higher levels leading to a decrease in mixing performance. This occurs as large agglomerates are formed and are not broken apart by shear leading to poor mixing. Pressure and shear stress profiles were shown to be affected by the amount of moisture in the system. The extent of agglomeration at different moisture contents was quantified via the discrete element simulations. Agglomerate size distributions and morphology were shown to be strong functions of moisture content. © 2012 American Institute of Chemical Engineers AIChE J, 2012
Ammonia absorption at haber process conditions
Authors: Huberty Mark S. , Wagner Andrew L. , McCormick Alon , Cussler Edward 
Published: January 2012

AbstractThe kinetics of ammonia absorption into magnesium chloride is measured as ammonia pressure change in the temperature range 170‐430°C. The actual pressure minus that at equilibrium drops quickly, with a half life of less than a minute. It varies with the square‐root of time, suggesting diffusion limited absorption. The diffusion coefficient of ammonia in solid magnesium chloride inferred from these data is on the order 10−11‐10−13 cm2/s, considerably faster than many solid‐phase diffusivities. While optical microscopy and BET surface area experiments indicate recrystallization and agglomeration of the absorbent at ammonia synthesis temperatures, the absorption rate remains high. The dependence of absorption rate on temperature, particle size and the presence of a silica support is also investigated. The results suggest both improved ammonia separation and ways to develop high‐conversion, small‐scale, multifunctional ammonia synthesis reactors. © 2012 American Institute of Chemical Engineers AIChE J, 2012
Integration of COSMO‐based methodologies into commercial process simulators: Separation and purification of reuterin
Authors: Ferro V. R. , Ruiz E. , Tobajas M. , Palomar J. F. 
Published: January 2012

AbstractThe conceptual design of a new process is developed via computer‐aided simulation for separating and purifying reuterin, an antimicrobial substance obtained by bacterial fermentation of glycerol, from its mixture with the nonfermented substrate, the main subproduct of the process (1,3‐propanediol) and water. The nondatabank components included in the simulations are created by using the structures derived from quantum mechanical calculations and the properties (molecular weight, normal boiling point, and mass density) estimated by COSMO‐RS method. The unknown remainder properties are estimated by the methods and models used by default in Aspen Plus (v7.3). The COSMOSAC property model, also implemented in Aspen Plus, is specified with the molecular volumes and sigma profiles obtained by COSMO‐RS. The properties (boiling temperatures, densities, VL equilibria, etc.) predicted for glycerol, 1,3‐propanediol, water, and their mixtures by COSMO‐based methods agree reasonably well with experimental reported values, whereas those obtained for reuterin derivatives are consistent with the behavior of amphoteric compounds having strong capabilities to interact attractively with hydrogen donor and acceptor groups all together. The process consists of a two‐stage distillation operation, the first of which removes the water and the second one separates reuterin as a 99.5 wt %‐pure bottom product. The second column operates at low pressure (ca. 40 kPa) to avoid thermal decomposition of reuterin (over 280°C) and guaranties 99.9% recovery of the desired product. Water removing offers different heat integration and energy‐saving opportunities considering that condenser pressure of the first column can be increased to ∼15 bar preserving the thermal integrity of the reuterin. Dimensions of the equipments as well as capital and operating costs are evaluated. © 2012 American Institute of Chemical Engineers AIChE J, 2012
The influence of the surface character of the clays on the properties of poly(p‐dioxanone)/fibrous clay nanocomposites
Authors: Qiu Zhi‐Cheng , Zhang Jing‐Jing , Huang Cai‐Li , Niu Ying , Yang Ke‐Ke , Wang Yu‐Zhong 
Published: January 2012

AbstractTwo different fibrous clays, halloysite nanotubes (HNTs) and organically modified attapulgite (OAT), were chosen to prepare poly(p‐dioxanone) (PPDO)/clay nanocomposites by in‐situ polymerization. The influence of surface character and geometric structure of the clays on the properties of the nanocomposites were investigated systematically concerning with their crystallization behaviors, thermal stabilities, rheological behaviors, and mechanical performances. The effect of clay content on the properties of the nanocomposites was also discussed, taking PPDO/HNTs nanocomposites for example. The results showed that HNTs was more effective in improving the crystallization rate, thermal stability as well as mechanical performance. In addition, the crystallization rate and rigidity of nanocomposites increased with increasing HNTs loading. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Encapsulation of nano Disperse Red 60 via modified miniemulsion polymerization. I. Preparation and characterization
Authors: El‐sayed Galila M. , Kamel M. M. , Morsy N. S. , Taher F. A. 
Published: January 2012

AbstractNanocolorant, nano Disperse Red 60, was successfully prepared via modified miniemulsion polymerization process. Transmission electron microscopy was employed to determine the droplet and particle sizes. The effects of the speed and the time of homogenization, the surfactant nature and its amount, the presence of dye, the initiator nature, and the presence of a crosslinker on the morphology and particle size of nanocolorant were studied. UV–vis absorption spectra of nanocolorant with respect to the commercial corresponding dye showed a hypsochromic shift confirming the decrease in particle size. Fourier transform infrared spectra proved the chemical composition of nanocolorant particles assisting the incorporation of the dye within the polystyrene particles. The monomer conversion, surface tension, and apparent sedimentation stability also were measured. The relative electrical conductivity of the suspension was used for determining the polymerization mechanism. The kinetic polymerization was investigated using a pseudofirst‐order and it is found that the rate constant of polymerization equals 0.01358 min−1. Zeta potential measurements were employed for miniemulsion which showed that it has good stability at all range of pH. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Stage Fright and Joy: Performers in Relation to the Troupe, Audience, and Beyond
Authors: Simmonds Janette Graetz , Southcott Jane E. 
Published: January 2012

ABSTRACTWhen a performer gives a public performance, there is awareness and some form of engagement with the group of people who constitute the audience. Perceptions of this “audience group” may affect the performer in various ways, sometimes contributing to “stage fright”, sometimes stimulating the performer to an especially uplifting and thrilling performance. Depending on their art form, performers may also be highly conscious of another group (in some arts referred to as a troupe), their fellow actors, dancers, vocalists or musicians. In this paper, we review relevant psychoanalytic, psychological and theater literature. We then report on findings from an aspect of our qualitative research into performance anxiety with musicians, actors, and public speakers who were interviewed concerning their experiences of performing. These performers gave detailed reflections on their relationship with audiences and fellow performers and experiences of performing, including debilitating fright, but also those of an uplifting, joyous, sometimes spiritual nature. Copyright © 2012 John Wiley & Sons, Ltd.
Magnetic field measurements of CP stars from hydrogen line cores
Authors: Kudryavtsev D.O. , Romanyuk I.I. 
Published: January 2012

AbstractWe present the results of measurements of magnetic fields of chemically peculiar (CP) stars, performed from the shifts between the circularly polarized components of metal and hydrogen lines (the Babcock method). The observations are carried out with an analyzer of circular polarization at the 6‐m telescope of the SAO RAS. We found that for the absolute majority of the objects studied (in 22 CP stars out of 23), the magnetic fields, determined from the Zeeman shifts in the hydrogen line cores, are significantly lower than those obtained from metal lines in the same spectra. This disparity varies between the stars. We show that instrumental effects can not produce the above features, and discuss the possible causes of the observed effect. The discovered condition reveals a more complicated structure of magnetic fields of CP stars than a simple dipole, in particular, a reduction of the field strength in the upper atmosphere with the vertical gradient, significantly higher than the dipole (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A search for magnetic fields in cool sdB stars
Authors: Mathys G. , Hubrig S. , Mason E. , Michaud G. , Schöller M. , Wesemael F. 
Published: January 2012

AbstractHot cluster horizontal branch (HB) stars and field subdwarf B (sdB) stars are core helium burning stars that exhibit abundance anomalies that are believed to be due to atomic diffusion. Diffusion can be effective in these stars because they are slowly rotating. In particular, the slow rotation of the hot HB stars (Teff > 11000 K), which show abundance anomalies, contrasts with the fast rotation of the cool HB stars, where the observed abundances are consistent with those of red giants belonging to the same cluster. The reason why sdB stars and hot HB stars are rotating slowly is unknown. In order to assess the possible role of magnetic fields on abundances and rotation, we investigated the occurrence of such fields in sdB stars with Teff < 30 000 K, whose temperatures overlap with those of the hot HB stars. We conclude that large‐scale organised magnetic fields of kG order are not generally present in these stars but at the achieved accuracy, the possibility that they have fields of a few hundred Gauss remains open. We report the marginal detection of such a field in SB 290; further observations are needed to confirm it (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
T Tauri star magnetic fields and magnetospheres
Authors: Hussain G.A.J. 
Published: January 2012

AbstractStellar magnetic fields govern key aspects of the evolution of a young star, from controlling accretion to regulating the angular momentum evolution of the system. Spectro‐polarimetric studies of T Tauri stars have revealed a surprising range of magnetic field topologies. Meanwhile multi‐wavelength campaigns have probed T Tauri star systems from stellar photosphere to inner disk, allowing us to study magnetospheric accretion in unprecedented detail. We review recent results and discuss their implications for understanding the evolution of young stars (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The statistical study of quasi‐periodic oscillations of the radio emission in solar quiet regions
Authors: Kallunki J. , Riehokainen A. 
Published: January 2012

AbstractIn this study we discuss variations of the radio emission from the Quiet Sun Areas (QSA) at centimeter wavelength (1.76 cm). Data were obtained from Nobeyama Radioheliograph (NoRH). Oscillations of selected areas were studied carefully from data taken over one week. We try to find quasi‐periodic solar oscillations from the QSA. We used the traditional Fast Fourier Transform (FFT), Global Wavelet Spectrum (GWS) and Wavelet (Morlet) for studying signals in the frequency/time‐frequency domain. We used the Fisher randomization test to verify the significance of the observed signal. Instrumental and sky noises were studied using a cross‐correlation analysis. Additionally, a single pixel analysis were done. Wide ranges of solar oscillation periods were found from the Quiet Sun Area (QSA): 3–15, 35–70, and 90 minutes. Some physical explanations are suggested for these oscillations. However, it is not possible to give a conclusive statement about the origin of the long quasi‐periodic (>60 min) oscillations from the QSA (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Limited diversity of the interstellar extinction law
Authors: Krełowski J. , Strobel A. 
Published: January 2012

AbstractWe have applied the method of investigating extinction curves using statistically meaningful samples that was proposed by us 25 years ago. The extensive data sets of the ANS (Astronomical Netherlands Satellite) and 2MASS (Two Micron All Sky Survey) were used, together with UBV photometry to create average extinction curves for samples of OB stars. Our results demonstrate that in the vast majority of cases the extinction curves are very close to the mean galactic extinction curve. Only a few objects were found to be obviously discrepant from the average. The latter phenomenon may be related to nitrogen chemistry in translucent interstellar clouds (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Suppression of the large‐scale Lorentz force by turbulence
Authors: Rüdiger G. , Kitchatinov L.L. , Schultz M. 
Published: January 2012

AbstractThe components of the total stress tensor (Reynolds stress plus Maxwell stress) are computed within the quasilinear approximation for a driven turbulence influenced by a large‐scale magnetic background field. The conducting fluid has an arbitrary magnetic Prandtl number and the turbulence without the background field is assumed as homogeneous and isotropic with a free Strouhal number St. The total large‐scale magnetic tension is always reduced by the turbulence with the possibility of a ‘catastrophic quenching’ for large magnetic Reynolds number Rm so that even its sign is reversed. The total magnetic pressure is enhanced by turbulence in the high‐conductivity limit but it is reduced in the low‐conductivity limit. Also in this case the sign of the total pressure may reverse but only for special turbulences with sufficiently large St > 1. The turbulence‐induced terms of the stress tensor are suppressed by strong magnetic fields. For the tension term this quenching grows with the square of the Hartmann number of the magnetic field. For microscopic (i.e. small) diffusivity values the magnetic tension term becomes thus highly quenched even for field amplitudes much smaller than their equipartition value. In the opposite case of large‐eddy simulations the magnetic quenching is only mild but then also the turbulence‐induced Maxwell tensor components for weak fields remain rather small (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evidence of gene‐environment interaction for the RUNX2 gene and environmental tobacco smoke in controlling the risk of cleft lip with/without cleft palate
Authors: Wu Tao , Fallin M. Daniele , Shi Min , Ruczinski Ingo , Liang Kung Yee , Hetmanski Jacqueline B. , Wang Hong , Ingersoll Roxann G. , Huang Shangzhi , Ye Xiaoqian , Wu‐Chou Yah‐Huei , Chen Philip K. , Jabs Ethylin Wang , Shi Bing , Redett Richard , Scott Alan F. , Murray Jeffrey C. , Marazita Mary L. , Munger Ronald G. , Beaty Terri H. 
Published: January 2012

AbstractThis study examined the association between 49 markers in the Runt‐related transcription factor 2 (RUNX2) gene and nonsyndromic cleft lip with/without cleft palate (CL/P) among 326 Chinese case‐parent trios, while considering gene‐environment (GxE) interaction and parent‐of‐origin effects. Five single‐nucleotide polymorphisms (SNPs) showed significant evidence of linkage and association with CL/P and these results were replicated in an independent European sample of 825 case‐parent trios. We also report compelling evidence for interaction between markers in RUNX2 and environmental tobacco smoke (ETS). Although most marginal SNP effects (i.e., ignoring maternal exposures) were not statistically significant, eight SNPs were significant when considering possible interaction with ETS when testing for gene (G) and GxE interaction simultaneously or when considering GxE alone. Independent samples from European populations showed consistent evidence of significant GxETS interaction at two SNPs (rs6904353 and rs7748231). Our results suggest genetic variation in RUNX2 may influence susceptibility to CL/P through interacting with ETS. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.
Retracted: Terbium‐sensitized fluorescence method for the determination of dopamine in biological fluids and tablet formulation
Authors: Shahinfard Vahid , Ehsani Ali , Panahi‐Azar Vahid , Yousefi Negar Kabir , Jalali Morteza Salek 
Published: January 2012

ABSTRACTThe following article from Luminescence, Terbium‐sensitized fluorescence method for the determination of dopamine in biological fluids and tablet formulation by Vahid Shahinfard, Ali Ehsani, Vahid Panahi‐Azar, Negar Kabir Yousefi and Morteza Salek Jalali, published online on 12th January 2012 in Wiley Online Library (www.onlinelibrary.wiley.com), has been retracted by agreement between the authors, the journal Editor in Chief, Professor L. J. Kricka and Wiley‐Blackwell. The retraction has been agreed due to data in the article is not being reproducible. Copyright © 2012 John Wiley & Sons, Ltd.