bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alkylations of N4‐(4‐Pyridyl)‐3,5‐di(2‐pyridyl)‐1,2,4‐triazole: First Observation of Room‐Temperature Rearrangement of an N4‐Substituted Triazole to the N1 Analogue
Authors: Kitchen Jonathan A. , Larsen David S. , Brooker Sally 
Published: March 2010

AbstractAttempts to use alkylation to introduce a positive charge at the nitrogen atom of the 4‐pyridyl ring in the bis(bidentate) triazole ligand N4‐(4‐pyridyl)‐3,5‐di(2‐pyridyl)‐1,2,4‐triazole (pydpt) were made to ascertain what effect a strongly electron‐withdrawing group would have on the magnetic properties of any subsequent iron(II) complexes. Alkylation of pydpt under relatively mild conditions led in some cases to unexpected rearrangement products. Specifically, when benzyl bromide is used as the alkylating agent, and the reaction is carried out in refluxing acetonitrile, the N4 substituent moves to the N1 position. However, when the same reaction is performed in dichloromethane at room temperature, the rearrangement does not occur and the desired product containing an alkylated N4 substituent is obtained. Heating a pure sample of N4‐Bzpydpt⋅Br to reflux in MeCN resulted in clean conversion to N1Bzpydpt.Br. This is consistent with N4‐Bzpydpt.Br being the kinetic product whereas N1Bzpydpt.Br is the thermodynamic product. When methyl iodide is used as the alkylating agent, the N4 to N1 rearrangement occurs even at room temperature, and at reflux pydpt is doubly alkylated. The observation of the lowest reported temperatures for an N4 to N1 rearrangement is due to this particular rearrangement involving nucleophilic aromatic substitution: a possible mechanism for this transformation is suggested.
The evolution of chaos in active galaxy models with an oblate or a prolate dark halo component
Authors: Caranicolas N.D. , Zotos E.E. 
Published: March 2010

AbstractThe evolution of chaotic motion in a galactic dynamical model with a disk, a dense nucleus and a flat biaxial dark halo component is investigated. Two cases are studied: (i) the case where the halo component is oblate and (ii) the case where a prolate halo is present. In both cases, numerical calculations show that the extent of the chaotic regions decreases exponentially as the scale‐length of the dark halo increases. On the other hand, a linear relationship exists between the extent of the chaotic regions and the flatness parameter of the halo component. A linear relationship between the critical value of the angular momentum and the flatness parameter is also found. Some theoretical arguments to support the numerical outcomes are presented. An estimation of the degree of chaos is made by computing the Lyapunov Characteristic Exponents. Comparison with earlier work is also made (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sixty four nights of UBV photometry of early‐type stars at La Sila
Authors: Mayer P. , Božić H. , Lorenz R. , Drechsel H. 
Published: March 2010

AbstractUBV measurements of early‐type stars, mostly eclipsing binaries, obtained at La Silla in the years 1990 to 1994 with the ESO 50 cm telescope are presented. Most of these data were already used in our individual studies of several binaries. Now all photometric measurements were reduced again with an advanced technique and are made available electronically. Our data for MY Ser have not yet been published; new light curve is given and solved. The result is that MY Ser is a contact binary, with very large fill‐out parameter. Also a light curve and its solution for V1051 Cen are provided, and the problem of the period of V871 Cen is pointed out. Besides binaries (and the comparison and check stars) data for several stars in southern H II regions are included. Extinction and transformation coefficients are given (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Four‐colour photometry of EY Dra: A study of an ultra‐fast rotating active dM1‐2e star
Authors: Vida K. , Oláh K. , Kőväri Zs. , Jurcsik J. , Sódor Á. , Váradi M. , Belucz B. , Dékány I. , Hurta Zs. , Nagy I. , Posztobányi K. 
Published: March 2010

AbstractWe present more than 1000‐day long photometry of EY Draconis in BV (RI)C passbands. The changes in the light curve are caused by the spottedness of the rotating surface. Modelling of the spotted surface shows that there are two large active regions present on the star on the opposite hemispheres. The evolution of the surface patterns suggests a flip‐flop phenomenon. Using Fourier analysis, we detect a rotation period of Prot = 0.45875 d, and an activity cycle with P ≈ 350 d, similar to the 11‐year long cycle of the Sun. This cycle with its year‐long period is the shortest one ever detected on active stars. Two bright flares are also detected and analysed (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carotenoid and fatty acid metabolism in light‐stressed Dunaliella salina
Authors: Lamers Packo P. , van de Laak Carlien C.W. , Kaasenbrood Petrouchka S. , Lorier Jeroen , Janssen Marcel , De Vos Ric C.H. , Bino Raoul J. , Wijffels René H. 
Published: March 2010

Abstractβ‐Carotene is overproduced in the alga Dunaliella salina in response to high light intensities. We have studied the effects of a sudden light increase on carotenoid and fatty acid metabolism using a flat panel photobioreactor that was run in turbidostat mode to ensure a constant light regime throughout the experiments. Upon the shift to an increased light intensity, β‐carotene production commenced immediately. The first 4 h after induction were marked by constant intracellular levels of β‐carotene (2.2 g LCV−1), which resulted from identical increases in the production rates of cell volume and β‐carotene. Following this initial phase, β‐carotene productivity continued to increase while the cell volume productivity dropped. As a result, the intracellular β‐carotene concentration increased reaching a maximum of 17 g LCV−1 after 2 days of light stress. Approximately 1 day before that, the maximum β‐carotene productivity of 30 pg cell−1 day−1 (equivalent to 37 mg LRV−1 day−1) was obtained, which was about one order of magnitude larger than the average productivity reported for a commercial β‐carotene production facility, indicating a vast potential for improvement. Furthermore, by studying the light‐induced changes in both β‐carotene and fatty acid metabolism, it appeared that carotenoid overproduction was associated with oil globule formation and a decrease in the degree of fatty acid unsaturation. Our results indicate that cellular β‐carotene accumulation in D. salina correlates with accumulation of specific fatty acid species (C16:0 and C18:1) rather than with total fatty acid content. Biotechnol. Bioeng. 2010;106: 638–648. © 2010 Wiley Periodicals, Inc.
Characterization and applications of serum‐free induced adhesion in jurkat suspension cells
Authors: Audiffred Julianne F. , De Leo Sarah E. , Brown Paige K. , Hale‐Donze Hollie , Monroe W. Todd 
Published: March 2010

AbstractIn this study, we demonstrate that the presence of serum in different media plays an important role in inducing transient and reversible adhesion in Jurkat suspension cells. Attachment of Jurkat cells in two distinct media formulations (serum‐fortified and serum‐free) to untreated polystyrene (PS), plasma‐treated PS, and fibronectin‐coated PS was compared. Additional analysis characterized the occurrence of this transient cell adhesion, including attachment rate, reversibility of attachment, and viability and preservation of phenotype in cells during and after attachment. As a demonstration of the utility of this technique, a few applications of transiently adhering Jurkat cells are shown which would be otherwise difficult with freely suspended cells, such as increased gene delivery, confocal‐based apoptosis detection, and real‐time electric‐field effect monitoring in Jurkat cells. Biotechnol. Bioeng. 2010;106: 784–793. © 2010 Wiley Periodicals, Inc.
Ring‐Opening Metathesis Polymerization Based Pore‐Size‐Selective Functionalization of Glycidyl Methacrylate Based Monolithic Media: Access to Size‐Stable Nanoparticles for Ligand‐Free Metal Catalysis
Authors: Bandari Rajendar , Höche Thomas , Prager Andrea , Dirnberger Klaus , Buchmeiser Michael R. 
Published: March 2010

AbstractMonolithic polymeric supports have been prepared by electron‐beam‐triggered free‐radical polymerization using a mixture of glycidyl methacrylate and trimethylolpropane triacrylate in 2‐propanol, 1‐dodecanol, and toluene. Under appropriate conditions, phase separation occurred, which resulted in the formation of a porous monolithic matrix that was characterized by large (convective) pores in the 30 μm range as well as pores of <600 nm. The epoxy groups in pores of >7 nm were hydrolyzed by using poly(styrenesulfonic acid) (Mw=69 400 g mol−1, PDI=2.4). The remaining epoxy groups inside pores of <7 nm were subjected to aminolysis with norborn‐5‐en‐2‐ylmethylamine (2) and provided covalently bound norborn‐2‐ene (NBE) groups inside these pores. These NBE groups were then treated with the first‐generation Grubbs initiator [RuCl2(PCy3)2(CHPh)]. These immobilized Ru–alkylidenes were further used for the surface modification of the small pores by a grafting approach. A series of monomers, that is, 7‐oxanorborn‐5‐ene‐2,3‐dicarboxylic anhydride (3), norborn‐5‐ene‐2,3‐dicarboxylic anhydride (4), N,N‐di‐2‐pyridyl‐7‐oxanorborn‐5‐ene‐2‐carboxylic amide (5), N,N‐di‐2‐pyridylnorborn‐5‐ene‐2‐carboxamide (6), N‐[2‐(dimethylamino)ethyl]bicyclo[2.2.1]hept‐5‐ene‐2‐carboxamide (7), and dimethyl bicyclo[2.2.1]hept‐5‐en‐2‐ylphosphonate (8), were used for this purpose. Finally, monoliths functionalized with poly‐5 graft polymers were used to permanently immobilize Pd2+ and Pt4+, respectively, inside the pores. After reduction, metal nanoparticles 2 nm in diameter were formed. The palladium‐nanoparticle‐loaded monoliths were used in both Heck‐ and Suzuki‐type coupling reactions achieving turnover numbers of up to 167 000 and 63 000, respectively.
N,N′‐Methylenediimidazolium Salts: From Self‐Assembly to an Efficient DNAse Protection System
Authors: Pardin Christophe , Leclercq Loïc , Schmitzer Andreea R. 
Published: March 2010

AbstractWe have developed N,N′‐dialkylmethylenediimidazolium salts ([CnCnDIM][X]2) that self‐organize into multilayered cationic vesicles and can interact with DNA. These preorganized systems form complexes with linear DNA and protect it from DNase I cleavage.
Homoleptic Tris(Pyridyl Pyrazolate) IrIII Complexes: En Route to Highly Efficient Phosphorescent OLEDs
Authors: Chen Kellen , Yang Cheng‐Han , Chi Yun , Liu Chao‐Shiuan , Chang Chih‐Hao , Chen Chung‐Chia , Wu Chung‐Chih , Chung Min‐Wen , Cheng Yi‐Ming , Lee Gene‐Hsiang , Chou Pi‐Tai 
Published: March 2010

AbstractTreatment of the metal reagent IrCl3⋅nH2O with two equivalents of 2‐pyridyl pyrazole (N^N)H (3‐tert‐butyl‐5‐(2‐pyridyl) pyrazole, (bppz)H and 3‐trifluoromethyl‐5‐(2‐pyridyl) pyrazole, (fppz)H), afforded the isomeric IrIII metal complexes with a general formula cis‐[Ir(bppz)2Cl2]H (2 a), trans‐[Ir(bppz)2Cl2]H (3 a), cis‐[Ir(fppz)2Cl2]H (2 b), and trans‐[Ir(fppz)2Cl2]H (3 b). Single‐crystal X‐ray diffraction studies on 2 b and 3 a revealed the coexistence of two pyrazolate chelates and two terminal chloride ligands on the coordination sphere. Subsequent reactivity studies confirmed their intermediacy to the preparation of homoleptic mer‐[Ir(bppz)3] (1 a) and mer‐[Ir(fppz)3] (1 b) that showed dual intraligand and ligand‐to‐ligand charge‐transfer phosphorescence at room temperature. To attain bright, room‐temperature phosphorescence further, we then synthesized two isoquinolinyl pyrazolate complexes, mer‐[Ir(bipz)3] (4 a) and mer‐[Ir(fipz)3] (4 b) ((bipz)H=3‐tert‐butyl‐5‐(1‐isoquinolyl) pyrazole and (fipz)H=3‐trifluoromethyl‐5‐(1‐isoquinolyl) pyrazole). Their orange luminescence is mainly attributed to the mixed MLCT/ππ* transition, and the quantum yields were as high as 86 (4 a) and 50 % (4 b) in degassed CH2Cl2 solution at RT. The organic light‐emitting diodes (OLEDs) were then fabricated by using 4 a as a dopant, giving orange luminescence with CIEx,y=0.55, 0.45 (CIEx,y=the 1931 Commission Internationale de L’Eclairage (x,y) coordinates) and peak efficiencies of 14.6 % photon/electron, 34.8 cd A−1, 26.1 lm W−1. The device data were then compared with the previously reported heteroleptic complex [Ir(dfpz)2(bipz)] (5) ((dfpz)H=1‐(2,4‐difluorophenyl) pyrazole), revealing the possible effect of the bipz chelate and phosphor design on the overall electrophosphorescent performance, which can be understood by the differences in the carrier‐transport properties.
A Conjugated Thiophene‐Based Rotaxane: Synthesis, Spectroscopy, and Modeling
Authors: Zalewski Leszek , Wykes Michael , Brovelli Sergio , Bonini Massimo , Breiner Thomas , Kastler Marcel , Dötz Florian , Beljonne David , Anderson Harry L. , Cacialli Franco , Samorì Paolo 
Published: March 2010

AbstractA dithiophene rotaxane 1⊂β‐CD and its shape‐persistent corresponding dumbbell 1 were synthesized and fully characterized. 2D NOESY experiments, supported by molecular dynamics calculations, revealed a very mobile macrocycle (β‐CD). Steady‐state and time‐resolved photoluminescence experiments in solution were employed to elucidate the excited‐state dynamics for both systems and to explore the effect of cyclodextrin encapsulation. The photoluminescence (PL) spectrum of 1⊂β‐CD was found to be blueshifted with respect to the dumbbell 1 (2.81 and 2.78 eV, respectively). Additionally, in contrast to previous observations, neither PL spectra nor the decay kinetics of both threaded and unthreaded systems showed changes upon increasing the concentration or changing the polarity of the solutions, thereby providing evidence for a lack of tendency toward aggregation of the unthreaded backbone.
Study of the Light‐Induced Spin Crossover Process of the [FeII(bpy)3]2+ Complex
Authors: de Graaf Coen , Sousa Carmen 
Published: March 2010

AbstractAb initio calculations have been performed on [FeII(bpy)3]2+ (bpy=bipyridine) to establish the variation of the energy of the electronic states relevant to light‐induced excited‐state spin trapping as a function of the Feligand distance. Light‐induced spin crossover takes place after excitation into the singlet metal‐to‐ligand charge‐transfer (MLCT) band. We found that the corresponding electronic states have their energy minimum in the same region as the low‐spin (LS) state and that the energy dependence of the triplet MLCT states are nearly identical to the 1MLCT states. The high‐spin (HS) state is found to cross the MLCT band near the equilibrium geometry of the MLCT states. These findings give additional support to the hypothesis of a fast singlet–triplet interconversion in the MLCT manifold, followed by a 3MLCT–HS (5T2) conversion accompanied by an elongation of the FeN distance.
A Highly Potent and Selective Caspase 1 Inhibitor that Utilizes a Key 3‐Cyanopropanoic Acid Moiety
Authors: Boxer Matthew B. , Quinn Amy M. , Shen Min , Jadhav Ajit , Leister William , Simeonov Anton , Auld Douglas S. , Thomas Craig J. 
Published: March 2010

AbstractHerein, we examine the potential of a nitrile‐containing propionic acid moiety as an electrophile for covalent attack by the active‐site cysteine residue of caspase 1. The syntheses of several cyanopropanate‐containing small molecules based on the optimized peptidic scaffold of prodrug VX‐765 were accomplished. These compounds were found to be potent inhibitors of caspase 1 (IC50 values ≤1 nM). Examination of these novel small molecules against a caspase panel demonstrated an impressive degree of selectivity for caspase 1 inhibition over other caspase isozymes. Assessment of hydrolytic stability and selected ADME properties highlighted these agents as potentially useful tools for studying caspase 1 down‐regulation in various settings, including in vivo analyses.
An efficient curvilinear non‐hydrostatic model for simulating surface water waves
Authors: Choi Doo Yong , Wu Chin H. , Young Chih‐Chieh 
Published: March 2010

AbstractAn efficient curvilinear non‐hydrostatic free surface model is developed to simulate surface water waves in horizontally curved boundaries. The generalized curvilinear governing equations are solved by a fractional step method on a rectangular transformed domain. Of importance is to employ a higher order (either quadratic or cubic spline function) integral method for the top‐layer non‐hydrostatic pressure under a staggered grid framework. Model accuracy and efficiency, in terms of required vertical layers, are critically examined on a linear progressive wave case. The model is then applied to simulate waves propagating in a canal with variable widths, cnoidal wave runup around a circular cylinder, and three‐dimensional wave transformation in a circular channel. Overall the results show that the curvilinear non‐hydrostatic model using a few, e.g. 2–4, vertical layers is capable of simulating wave dispersion, diffraction, and reflection due to curved sidewalls. Copyright © 2010 John Wiley & Sons, Ltd.
Characterization of poly(ethylene glycol) gels with added collagen for neural tissue engineering
Authors: Scott Rebecca , Marquardt Laura , Willits Rebecca Kuntz 
Published: March 2010

AbstractOver the past decade, it has been increasingly recognized that both chemical and mechanical properties of scaffolds influence neural cell behavior, ranging from growth to differentiation to migration. However, mechanical properties are difficult to control for in the design of scaffolds for nerve regeneration, as properties change over time for most biologically derived scaffolds. The focus of this project was to examine how the mechanical properties of a nondegradable scaffold, poly(ethylene glycol) (PEG) gels, influenced nerve cell behavior. Low concentration PEG gels, of 3, 4, or 5% PEG, with added collagen to alter chemical properties were examined for both their mechanical properties and their ability to support nerve expression and extension. Stiffness (G*) significantly increased with increased PEG concentration. The addition of chemically conjugated collagen significantly decreased the stiffness compared to plain gels. This phenomenon was confirmed to be an effect of the conjugate, and not the protein itself, as G* of gels containing conjugate, but no protein, was not significantly different than G* of gels with conjugated protein. PC12 cell neurite expression increased with decreasing PEG and increasing collagen concentration. At its best, the expression approached the value on collagen‐coated tissue culture plastic, which is a substantial improvement over previous studies on PEG. Neurite extension of dorsal root ganglia was also improved on these same gels over gels with either higher PEG concentration or lower collagen amount. Overall, these results suggest that exploration of lower stiffness materials is necessary to improve neurite growth and extension in three‐dimensional synthetic scaffolds. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Mechanism and Modeling of Emulsion Polymerization: New Ideas and Concepts – 1. Particle Nucleation
Authors: Tauer Klaus , Nazaran Pantea 
Published: March 2010

AbstractSummary: New experimental data for nucleation in emulsion polymerization prove that the process is heterogeneous in nature so that water‐borne oligomers precipitate at the surface of monomer drops. The particle morphology at the early stage of the process is strongly influenced by the initiator concentration. The hydrophilicity of the monomer is less important as methyl methacrylate, styrene, and 4‐tert‐butyl styrene show similar behaviour.
Dissipative Structure in the Course of Drying Suspensions and Solutions
Authors: Okubo Tsuneo 
Published: March 2010

AbstractSummary: Convectional, sedimentation and drying dissipative patterns during the course of dryness of suspensions and solutions are reviewed. The whole processes of convection were analyzed in the seven steps: irregular circulation accompanied with the upward heat transportation, global convectional flow from the central area toward outside edge at the surface layers of liquid, cooperative formation of distorted Benard cells, reversal of global flow of convection, growing of the spoke lines from the outside edge toward central area at the liquid surface layers, cluster and further bundle formation of the spoke lines, and the convectional flow by the pinning effect. The sedimentary colloidal particles were suspended above the substrate by the electric double layers and moved by the balancing of the external force fields including convectional flow and sedimentation. Principal macroscopic drying patterns are broad rings and spoke lines. Microscopic patterns such as star, needle, street road, string and cross‐like are formed. The stratified structures form from micro to macro scales. Information on the size, shape, conformation and/or flexibility of particles or polymers is transferred cooperatively, and further accompanied with the amplification and selection processes during the course of dryness.
Photon Trapping and the Enhancement of Electronic Excitation Energy Transfer Efficiency Caused by Colloidal Crystals
Authors: Tsuchida Akira , Ohi Yuji , Takahashi Shinya , Kimura Hiroshi , Okubo Tsuneo 
Published: March 2010

AbstractSummary: The efficiency of electronic excitation energy transfer from photoexcited fluorescein to rhodamine 6G is enhanced by 2.26 times in an exhaustively deionized colloidal silica suspension. This enhancement is caused by the photon trapping effects due to the Bragg reflection of colloidal crystals formed in the suspension. The lower enhancement efficiency of 1.41 times observed for rhodamine B as an acceptor is attributed to the inefficient spectral overlap between donor fluorescence and acceptor absorption bands.
Quantification method affects estimates of voluntary quadriceps activation
Authors: Krishnan Chandramouli , Williams Glenn N. 
Published: March 2010

AbstractThe aim of this study was to investigate the effect of quantification method on estimates of voluntary quadriceps muscle activation. Twenty‐two people with no history of serious lower extremity injuries underwent voluntary quadriceps activation testing at 60° of knee flexion. Estimates of quadriceps activation were derived with: (1) a formula based on the interpolated twitch technique (ITT); (2) the central activation ratio (CAR); and (3) a modified central activation ratio. Predictive equations were developed that describe the relationships between the three methods. Significant differences (P < 0.001) were observed between the estimates of voluntary quadriceps muscle activation obtained using the three methods (ITT percent activation = 93.0 ± 6.4%, CAR = 95.9 ± 3.8%, modified CAR = 98.5 ± 4.1%). Excellent correlation (r = 0.995) was observed between ITT‐based percent activation and the CAR method. The associations between these methods and the modified CAR approach were weaker. Quantification method affects activation estimates. The equations developed will assist scientists in accurately comparing the results of studies that use different methods of quantifying activation. Muscle Nerve, 2010