bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solvent‐ and thermal‐induced crystallization of poly‐L‐lactic acid in supercritical CO2 medium
Authors: López‐Periago Ana , García‐González Carlos A. , Domingo Concepción 
Published: October 2008

AbstractThe effect of different annealing treatments with supercritical carbon dioxide (SCCO2) on the structural and mechanical properties of semicrystalline poly‐L‐lactic acid (L‐PLA) was investigated. 2000, 27,000, 100,000, and 350,000 g mol−1 molecular weight L‐PLA polymers were used in the study. The solid‐state processing of L‐PLA at temperatures lower than the effective melting point led to solvent‐ and thermal‐induced crystallization. Solvent‐induced and isothermal crystallization mechanisms could be considered similar regarding the increase of polymer chain mobility and mass‐transfer in the amorphous region; however, quite different microstructures were obtained. SCCO2 solvent‐induced crystallization led to polymers with high crystallinity and melting point. On the contrary, SCCO2 thermal‐induced crystallization led to polymers with high crystallinity and low melting point. For these polymers, the hardness increased and the elasticity decreased. Finally, the effect of dissolving SCCO2 in the molten polymer (cooling from the melt) was analyzed. Cooling from the melt led to polymers with high crystallinity, low melting point, low hardness, and low elasticity. Distinctive crystal growth and nucleation episodes were identified. This work also addressed the interaction of SCCO2‐drug (triflusal) solution with semicrystalline L‐PLA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Phosphorescence Color Tuning by Ligand, and Substituent Effects of Multifunctional Iridium(III) Cyclometalates with 9‐Arylcarbazole Moieties
Authors: Ho Cheuk‐Lam , Wang Qi , Lam Ching‐Shan , Wong Wai‐Yeung , Ma Dongge , Wang Lixiang , Gao Zhi‐Qiang , Chen Chin‐Hsin , Cheah Kok‐Wai , Lin Zhenyang 
Published: October 2008

AbstractThe synthesis, isomeric studies, and photophysical characterization of a series of multifunctional cyclometalated iridium(III) complexes containing a fluoro‐ or methyl‐substituted 2‐[3‐(N‐phenylcarbazolyl)]pyridine molecular framework are presented. All of the complexes are thermally stable solids and highly efficient electrophosphors. The optical, electrochemical, photo‐, and electrophosphorescence traits of these iridium phosphors have been studied in terms of the electronic nature and coordinating site of the aryl or pyridyl ring substituents. The correlation between the functional properties of these phosphors and the results of density functional theory calculations was made. Arising from the propensity of the electron‐rich carbazolyl group to facilitate hole injection/transport, the presence of such a moiety can increase the highest‐occupied molecular orbital levels and improve the charge balance in the resulting complexes relative to the parent phosphor with 2‐phenylpyridine ligands. Remarkably, the excited‐state properties can be manipulated through ligand and substituent effects that allow the tuning of phosphorescence energies from bluish green to deep red. Electrophosphorescent organic light‐emitting diodes (OLEDs) with outstanding device performance can be fabricated based on these materials, which show a maximum current efficiency of approximately 43.4 cd A−1, corresponding to an external quantum efficiency of approximately 12.9 % ph/el (photons per electron) and a power efficiency of approximately 33.4 Lm W−1 for the best device. The present work provides a new avenue for the rational design of multifunctional iridium–carbazolyl electrophosphors, by synthetically tailoring the carbazolyl pyridine ring that can reveal a superior device performance coupled with good color‐tuning versatility, suitable for multicolor‐display technology.
A DFT Study on the Reaction Pathways for CarbonCarbon Bond‐Forming Reactions between Propargylic Alcohols and Alkenes or Ketones Catalyzed by Thiolate‐Bridged Diruthenium Complexes
Authors: Sakata Ken , Miyake Yoshihiro , Nishibayashi Yoshiaki 
Published: October 2008

AbstractThe reaction pathways of two types of the carboncarbon bond‐forming reactions catalyzed by thiolate‐bridged diruthenium complexes have been investigated by density‐functional‐theory calculations. It is clarified that both carboncarbon bond‐forming reactions proceed through a ruthenium–allenylidene complex as a common reactive intermediate. The attack of π electrons on propene or the vinyl alcohol on the ruthenium–allenylidene complex is the first step of the reaction pathways. The reaction pathways are different after the attack of nucleophiles on the ruthenium–alkynyl complex. In the reaction with propene, the carboncarbon bond‐forming reaction proceeds through a stepwise process, whereas in the reaction with vinyl alcohol, it proceeds through a concerted process. The interactions between the ruthenium–allenylidene complex and propene or vinyl alcohol have been investigated by applying a simple way of looking at orbital interactions.
Tetrahedral Oligothiophenes; Synthesis, X‐ray Analysis, and Optoelectronic Properties of Highly Symmetrical, 3D‐Branched Oligothiophenes
Authors: Matsumoto Kouzou , Tanaka Toru , Kugo Sota , Inagaki Takuya , Hirao Yoshikazu , Kurata Hiroyuki , Kawase Takeshi , Kubo Takashi 
Published: October 2008

AbstractTetrakis(bithienyl)methane and tetrakis(terthienyl)methane have been synthesized from tetrakis(2‐thienyl)methane by use of Suzuki–Miyaura coupling as a key reaction. Their trimethylsilyl (TMS) derivatives are also synthesized. X‐ray analysis reveals that each oligothiophene moiety tends to adopt anti‐conformations and show relatively small torsion angles between the adjacent thiophene rings. While the longest absorption maxima of these tetrakis(oligothienyl)methanes exhibit only a slight bathochromic shift compared to the corresponding linear oligothiophene derivative, tetrakis(bithienyl)methane and its TMS derivative exhibit an appreciable red‐shift in their fluorescence spectra. The intramolecular interaction between thienyl groups of tetrakis(2‐thienyl)methane is supported by DFT calculation.
3‐ Instead of 4‐Helix Formation in a De Novo Designed Protein in Solution Revealed by Small‐Angle X‐ray Scattering
Authors: Høiberg‐Nielsen Rasmus , Tofteng Shelton A. Pernille , Sørensen Kasper K. , Roessle Manfred , Svergun Dimitri I. , Thulstrup Peter W. , Jensen Knud J. , Arleth Lise 
Published: October 2008

AbstractDe novo design and chemical synthesis of proteins and their mimics are central approaches for understanding protein folding and accessing proteins with novel functions. We have previously described carbohydrates as templates for the assembly of artificial proteins, so‐called carboproteins. Here, we describe the preparation and structural studies of three α‐helical bundle carboproteins, which were assembled from three different carbohydrate templates and one amphiphilic hexadecapeptide sequence. This heptad repeat peptide sequence has been reported to lead to 4‐α‐helix formation. The low resolution solution structures of the three carboproteins were analyzed by means of small‐angle X‐ray scattering (SAXS) and synchrotron radiation circular dichroism (SRCD). The ab initio SAXS data analysis revealed that all three carboproteins adopted an unexpected 3+1‐helix folding topology in solution, while the free peptide formed a 3‐helix bundle. This finding is consistent with the calculated α‐helicities based on the SRCD data, which are 72 and 68 % for two of the carboproteins. The choice of template did not affect the overall folding topology (that is for the 3+1 helix bundle) the template did have a noticeable impact on the solution structure. This was particularly evident when comparing 4‐helix carboprotein monomers with the 2×2‐helix carboprotein dimer as the latter adopted a more compact conformation. Furthermore, the clear conformational differences observed between the two 4‐helix (3+1) carboproteins based on D‐altropyranoside and D‐galactopyranoside support the notion that folding is affected by the template, and subtle variations in template distance‐geometry design may be exploited to control the solution fold. In addition, the SRCD data show that template assembly significantly increases thermostability.
Structural and Immunochemical Analysis of the Lipopolysaccharide from Acinetobacter lwoffii F78 Located Outside Chlamydiaceae with a Chlamydia‐Specific Lipopolysaccharide Epitope
Authors: Hanuszkiewicz Anna , Hübner Göran , Vinogradov Evgeny , Lindner Buko , Brade Lore , Brade Helmut , Debarry Jennifer , Heine Holger , Holst Otto 
Published: October 2008

AbstractChemical analyses, NMR spectroscopy, and mass spectrometry were used to elucidate the structure of the rough lipopolysaccharide (LPS) isolated from Acinetobacter lwoffii F78. As a prominent feature, the core region of this LPS contained the disaccharide α‐Kdo‐(2→8)‐α‐Kdo (Kdo=3‐deoxy‐d‐D‐manno‐oct‐2‐ulopyranosonic acid), which so far has been identified only in chlamydial LPS. In serological investigations, the anti‐chlamydial LPS monoclonal antibody S25–2, which is specific for the epitope α‐Kdo‐(2→8)‐α‐Kdo, reacted with A. lwoffii F78 LPS. Thus, an LPS was identified outside Chlamydiaceae that contains a Chlamydia‐specific LPS epitope in its core region.
Natural Gum Reduced/Stabilized Gold Nanoparticles for Drug Delivery Formulations
Authors: Dhar Sheetal , Reddy E. Maheswara , Shiras Anjali , Pokharkar Varsha , Prasad B. L. V. 
Published: October 2008

Abstract“Gellan Gum”, widely used in food and confectionary industry as a thickening and gelling agent, has been employed as a reducing and stabilizing agent for the synthesis of gold nanoparticles. These nanoparticles display greater stability to electrolyte addition and pH changes relative to the traditional citrate and borohydride reduced nanoparticles. Subsequently these have been used to load anthracycline ring antibiotic doxorubicin hydrochloride. The drug loaded on these nanoparticles showed enhanced cytotoxic effects on human glioma cell lines LN‐18 and LN‐229.
Acceleration Effect of an Allylic Hydroxy Group on Ring‐Closing Enyne Metathesis of Terminal Alkynes: Scope, Application, and Mechanistic Insights
Authors: Imahori Tatsushi , Ojima Hidetomo , Yoshimura Yuichi , Takahata Hiroki 
Published: October 2008

AbstractAn interesting acceleration effect of an allylic hydroxy group on ring‐closing enyne metathesis has been found. Ring‐closing enyne metathesis of terminal alkynes possessing an allylic hydroxy group proceeded smoothly without the ethylene atmosphere generally necessary to promote the reaction. The synthesis of (+)‐isofagomine with the aid of this efficient reaction has been demonstrated. Mechanistic studies of the acceleration effect were also carried out. Results of NMR studies suggested that the reaction proceeded via an “ene‐then‐yne” pathway. Kinetic studies indicated switching of the rate‐determining step as a consequence of the presence of an allylic hydroxy group. These results suggest acceleration of the reentry step of Ru‐carbene species by the allylic hydroxy group.
Diamantelektroden in der dezentralen Abwasserbehandlung – elektrochemischer Abbau des chemischen Sauerstoffbedarfs organisch hochbelasteter Härtereiabwässer
Authors: Dittmar T. , Schmalz V. , Worch E. , Fischer D. 
Published: October 2008

AbstractEin elektrochemisches Verfahren zur dezentralen Behandlung von organisch hochbelasteten Industrieabwässern wird hier vorgestellt. Dazu wurden Diamantelektroden in verschiedenen diskontinuierlichen Laborreaktoren eingesetzt sowie der Einfluss der Stromdichte (8 – 66 mA/cm2) auf den Abbau des chemischen Sauerstoffbedarfs (CSB) untersucht. Dieser ließ sich mit Hilfe eines mathematischen Modells beschreiben. Das Verfahren ermöglichte die Einhaltung der Direkteinleitungskriterien.
Childhood and adolescent cancer survival in the US by race and ethnicity for the diagnostic period 1975‐1999
Authors: Linabery Amy M. , Ross Julie A. 
Published: October 2008

AbstractBACKGROUND.Survival trends provide a measure of improvement in detection and treatment over time. In the current study, updated childhood and adolescent cancer survival statistics are presented, overall and among demographic subgroups, including Hispanics, for whom to the authors' knowledge national rates have not been previously reported. These results extend those provided by the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program in their detail and interpretation.METHODS.Survival trends of primary cancers in children and adolescents (ages birth to 19 years) were evaluated using SEER 9 data. Five‐year and 10‐year relative survival rates across 5‐year (1975‐1979, 1985‐1989, and 1995‐1999) and 10‐year (1975‐1984 and 1985‐1994) cohorts were compared via Z‐tests. Annual percent change (APC) in survival was computed via weighted least‐squares regression. Rates in Hispanic children and adolescents were compared with those in non‐Hispanic whites and blacks (SEER 13, 1995‐1999).RESULTS.Five‐year survival rates increased significantly overall (1975‐1979: 63% vs 1995‐1999: 79%; P < .0001) and for nearly all histologic types examined; increases were greatest for ependymoma (+37%; P < .0001) and non‐Hodgkin lymphoma (+34%; P < .0001). Hispanic children and adolescents had somewhat poorer 5‐year rates than non‐Hispanic whites overall (74% vs 81%; P < .0001) and for Ewing sarcoma, leukemia, central nervous system tumors, and melanoma. Ten‐year rates also increased significantly overall (1975‐1984: 61% vs 1985‐1994: 72%; P < .0001) and for a majority of cancer types. The largest improvements were noted for acute lymphoblastic leukemia (+19%; P < .0001) and non‐Hodgkin lymphoma (+19%; P < .0001).CONCLUSIONS.Observed trends reinforce the need for resources devoted to advancing treatment modalities, reducing disparities among racial/ethnic groups and adolescents, and providing long‐term care of survivors. Cancer 2008. © 2008 American Cancer Society.
A pilot study of cognitive behaviour therapy for panic disorder augmented by panic surfing
Authors: Lamplugh Claire , Berle David , Milicevic Denise , Starcevic Vladan 
Published: October 2008

AbstractThis pilot study reports the outcome of cognitive behaviour therapy for panic disorder augmented by panic surfing. This treatment approach encourages acceptance of feelings rather than control of symptoms and anxiety, at the same time also targeting catastrophic misinterpretations, bodily vigilance and safety‐seeking behaviours. Eighteen participants completed a brief group treatment for panic disorder incorporating psychoeducation, panic surfing, interoceptive exposure, graded exposure and cognitive restructuring. Significant improvements occurred over the course of this treatment and were maintained at a 1‐month follow‐up. Results suggest that cognitive behaviour therapy augmented by panic surfing may be effective in the treatment of panic disorder, but there is a need for controlled studies and investigation of the relative contribution of its various components. Copyright © 2008 John Wiley & Sons, Ltd.
Using the Steepened Plasma Profile and Wave Breaking Threshold in Laser‐Plasma Interaction
Authors: Zobdeh P. , Sadighi‐Bonabi R. , Afarideh H. , Yazdani E. , Rezaei Nasirabad R. 
Published: October 2008

AbstractIn this work we evaluate the interaction of high intense laser beam with a steepened density profile. During laser interaction with underdense plasma by freely expanding plasma regime, modification of density profile is possible. In this paper we have investigated the ultra short laser pulse interaction with nonisothermal and collisionless plasma. We consider self–focusing as an effective nonlinear phenomenon that tends to increase when the laser power is more than critical rate. By leading the expanded plasma to a preferred location near to critical density, laser reflection is obtained, so the density profile will be locally steepened. The electromagnetic fields are evaluated in this new profile. We show the amplitude and period of electrical field oscillation are increased by reducing the steepened scale length. Also our numerical results identify that by reducing the steepened scale length, the electrical field is increased to wave breaking threshold limit. This high gradient electrical field causes the effective beam loading during the wave breaking phenomenon. The wave breaking can be the initial point for other acceleration regime as cavity or channel guiding regime. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Longitudinal Dust Lattice Shock Wave in a Strongly Coupled Complex Dusty Plasma
Authors: Ghosh S. 
Published: October 2008

AbstractThe effect of hydrodynamical damping that arises due to the irreversible processes within the system have been studied on 1D nonlinear longitudinal dust lattice wave (LDLW) in homogeneous strongly coupled complex (dusty) plasma. Analytical investigation shows that the nonlinear wave is governed by Korteweg‐de Vries Burgers' equation. This hydrodynamical damping induced dissipative effect is responsible for the Burgers' term that causes the generation of shock wave in dusty plasma crystal. Numerical investigation on the basis of the glow‐discharge plasma parameters reveal that LDLW exhibits both oscillatory and monotonic shock. The shock is compressive in nature and its strength decreases (increases) with the increase of the shielding parameter κ (characteristic length L). The effects of dust‐neutral collision are also discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transverse Optical Diagnostics for Intense Focused Heavy Ion Beams
Authors: Varentsov D. , Fertman A. D. , Turtikov V. I. , Ulrich A. , Wieser J. , Fortov V. E. , Golubev A. A. , Hoffmann D. H. H. , Hug A. , Kulish M. , Mintsev V. , Ni P. A. , Nikolaev D. , Sharkov B. Yu. , Shilkin N. , Ternovoi V. Ya. , Udrea S. 
Published: October 2008

AbstractBeam‐induced fluorescence of dense gas targets has been studied for its application to measure the transverse intensity distribution of energetic focused heavy ion beams. Mechanisms of light emission are discussed on the basis of measured wavelength‐ and time‐resolved light emission of argon. Gas pressures from 10 mbar up to 1 bar have been used. Transverse beam intensity profiles of 200 – 400 AMeV 238U pulses from the heavy ion synchrotron SIS‐18 at the Gesellschaft für Schwerionenforschung, Darmstadt, Germany with up to 5 · 109 particles per pulse focused to a sub‐millimeter spot have been recorded with argon and helium as target gases. Beam profiles recorded at the ArII lines by an optical filter resulted in the narrowest, most realistic beam diameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient and Flexible Solid‐Phase Synthesis of N‐Hydroxypolyamine Derivatives
Authors: Méret Michaël , Bienz Stefan 
Published: October 2008

AbstractOrthogonally protected, N‐hydroxylated, linear tri‐ and tetra‐amines were efficiently synthesised on Merrifield resin, which was modified with a phenethyl bromide linker. The polyamine frameworks were convergently prepared “from the centre” with reductive aminations and nucleophilic substitutions to elongate the polyamine backbone. The required N‐hydroxy groups were introduced during the cleavage of the polyamine derivatives from the resin through Cope elimination.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
An Overview of Syntheses of Apogalanthamine Analogues and 7‐Aza Derivatives of Steganacin and Steganone
Authors: Appukkuttan Prasad , Van der Eycken Erik 
Published: October 2008

AbstractA concise and critical overview of the developments in the synthesis of apogalanthamine analogues and steganacin and steganone 7‐aza analogues over the last four decades is presented. These amaryllidaceae alkaloid analogues bear a 5,6,7,8‐tetrahydrodibenz[c,e]azocine skeleton, and are well known for their diverse and potent biological activities. This microreview will briefly glance over the history and early developments in the field at the beginning, and will, in the latter parts, concentrate on the recent synthetic developments in the synthesis of the title molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Unsymmetrical Biaryls by Palladium‐Catalyzed Coupling of Aryl Halides with Internal Reduction
Authors: Satyanarayana Gedu , Maier Martin E. 
Published: October 2008

AbstractAryl bromides containing a (1,4,5,6‐tetrahydro‐6‐oxopyridin‐3‐yl)methyl substituent can be coupled with aryl halides yielding unsummetrical biaryls. In the course of this process, the cyclic enamide is oxidized to the 2(1H)‐pyridinone. The reaction proceeds by a six‐membered palladacycle resulting from allylic C–H bond activation of the cyclic enamide, leading to a six‐membered palladacycle. A subsequent transmetalation reaction with an aryl‐Pd‐X intermediate eventually leads to mixed biaryls by reductive elimination and β‐hydride elimination. The best yields were obtained with 2 equiv. of aryl halide. The required substrates were prepared from bromoiodobenzenes by a sequence consisting of a Heck reaction with allyl alcohol, enamine formation, Michael addition to ethyl acrylate, and heterocycle formation with benzylamine.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Yb Complexes with Amino‐Acid‐Armed Ligands for Direct Asymmetric Tandem Aldol Reduction Reactions
Authors: Stodulski Maciej , Jaźwiński Jarosław , Mlynarski Jacek 
Published: October 2008

AbstractA synthetic route to a series of C2‐symmetric chiral ligands armed with selectively protected amino acids have been developed with the aim to study the potential of the corresponding Yb(III) complexes for enantioselective direct aldol reactions. These ligands, which contain chiral bis(ester) or bis(amide) moieties, were readily prepared in enantiomerically pure form by the reaction of (S,S)‐hydrobenzoin or (S,S)‐diphenylethylenediamine with various chiral amino acids. In this article, the asymmetric aldol‐reduction reaction leading to 1,3‐diols (known as the aldol–Tishchenko reaction) has been performed with an elaborated family of ligands. This unique tandem reaction was catalysed by chiral Yb complexes that promote both the aldol reaction of unactivated carbonyl compounds and the Evans–Tishchenko reduction of the aldol intermediates. 1,3‐anti‐Diols with three stereogenic centers have been isolated as a result of the condensation of aliphatic ketones with aromatic aldehydes with up to 64 % ee. Additional detailed investigations of the nature of the binding of both class of ligands have also been carried out with high‐resolution 1H‐, 13C‐, and 14N‐NMR techniques.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
DFT/MM Study on Copper‐Catalyzed Cyclopropanation – Enantioselectivity with No Enthalpy Barrier
Authors: Drudis‐Solé Galí , Maseras Feliu , Lledós Agustí , Vallribera Adelina , Moreno‐Mañas Marcial 
Published: October 2008

AbstractThe enantioselectivity in the reaction of [Cu(adam‐box)(CHCO2Me)] {adam‐box = 2,2′‐isopropylidenebis[(4R)‐(1‐adamantyl)‐2‐oxazoline]} with Ph2C=CH2 was analyzed computationally by ONIOM(B3LYP:UFF) calculations. The lack of transition states in the potential‐energy surface precludes the use of conventional approaches and requires the definition of reaction paths in an approximate Gibbs free‐energy surface. The procedure is time consuming and intrinsically less accurate than the usual approaches based on enthalpic energy surfaces, but it produces results in reasonable agreement with experiment, which furthermore allow identification of the key interactions responsible for chiral discrimination.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)