bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Substituent Orientation on Selectivity between Polymerization and Cyclization: Polycondensation of (Alkylamino)benzoic Acid Dimer Phenyl Esters
Authors: Yokoyama Akihiro , Saito Shunsuke , Shimizu Yuuki , Yokozawa Tsutomu 
Published: November 2005

AbstractSummary: The polymerization characteristics of (octylamino)benzoic acid dimer phenyl esters with para‐meta (2), meta‐para (3), and meta‐meta (4) orientation of the amino and carbonyl groups were investigated. While treatment of 2 or 3 with a base gave the cyclic dimer 6 as the main product, condensation of 4 with an initiator in the presence of a base afforded polymers with narrow molecular weight distributions.The condensation of 4 with an initiator in the presence of a base afforded polymers with narrow molecular weight distribution.imageThe condensation of 4 with an initiator in the presence of a base afforded polymers with narrow molecular weight distribution.
Novel Nanoparticles Based on Dextran Esters with Unsaturated Moieties
Authors: Hornig Stephanie , Heinze Thomas , Hesse Stephanie , Liebert Tim 
Published: November 2005

AbstractSummary: Applying a dialysis process, new nanoparticles based on well‐defined dextran esters of furan‐2‐carboxylic‐ and pyroglutamic acids were prepared, which can undergo cross‐linking by UV irradiation. The highly functionalized products (total DS > 2) avoid the collapse of nanoparticles due to the prevention of hydrogen bond formation. The major fraction of the dextran ester nanospheres exhibits narrow size distribution down to 250 nm as mean diameter investigated by SEM.SEM images of dextran furoate pyroglutamate nanospheres.imageSEM images of dextran furoate pyroglutamate nanospheres.
Hydrogen‐Assisted Unique Incorporation of 1,4‐Divinylbenzene in Copolymerization with Propylene Using an Isospecific Zirconocene Catalyst
Authors: Cao Chengang , Dong Jin‐Yong , Chung Tze‐Chiang 
Published: November 2005

AbstractSummary: Propylene was copolymerized with 1,4‐divinylbenzene (1,4‐DVB) using rac‐Me2Si(2‐Me‐4‐Ph‐Ind)2ZrCl2 and MAO in the presence of hydrogen. 1H NMR spectra of the obtained copolymer confirmed the successful incorporation of 1,4‐DVB. 13C NMR analysis revealed a unique copolymer structure with the incorporated 1,4‐DVB units predominantly forming 1,4‐substituted phenyl repeating units in the polymer main chain. A plausible mechanism involving spontaneous insertion of terminal styryl into Zr‐H species was proposed to rationalize the unique incorporation of 1,4‐DVB.Copolymerization of propylene with 1,4‐divinylbenzene in the presence of hydrogen.imageCopolymerization of propylene with 1,4‐divinylbenzene in the presence of hydrogen.
Design of Surfactant‐Grafted Hydrogels with Fast Response to Temperature
Authors: Noguchi Yuji , Okeyoshi Kosuke , Yoshida Ryo 
Published: November 2005

AbstractSummary: Here we show a new design concept of functional polymer gel for rapid deswelling by utilizing micelle‐forming ability of surfactant. A thermosensitive polymer bearing a surfactant was synthesized by using N‐isopropylacrylamide and a reactive surfactant. Above lower critical solution temperature, the grafted surfactant acts to form micelle structure. In the shrinking process, the inside water is rapidly squeezed out through hydrophilic channel between the formed micelles and consequently the gel shrinks quickly.Shrinking mechanism of PNS gel in response to temperature increase.imageShrinking mechanism of PNS gel in response to temperature increase.
Minimizing transient times in a coupled solid‐state laser model
Authors: Lenhart S. , Protopopescu V. , Workman J. T. 
Published: November 2005

AbstractWe consider a system of ordinary differential equations modelling the dynamics of two coupled solid‐state lasers. Under the dynamics, this system may execute transitions between in‐phase and out‐of‐phase states. For satellite communications and high‐speed data transfer the transition times should be reduced to their shortest possible duration. In this paper, we apply optimal control theory to find the values of various laser parameters (e.g. the amplitude of the injected field, detunings, and coupling constants) which minimize the transient times between out‐of‐phase and in‐phase states. The effect of each parameter is shown to be independent of the other two, and the transient time is shown to be a strictly increasing function of detuning and a strictly decreasing function of the coupling constant and amplitude of the injected field. The effect of initial conditions on transient times is also analysed. Published in 2005 by John Wiley & Sons, Ltd.
Undersampled elliptical centric view‐order for improved spatial resolution in contrast‐enhanced MR angiography
Authors: Madhuranthakam Ananth J. , Hu Houchun H. , Barger Andrew V. , Haider Clifton R. , Kruger David G. , Glockner James F. , Huston John , Riederer Stephen J. 
Published: November 2005

AbstractAlthough contrast‐enhanced MR angiography (CE‐MRA) has been successfully developed into a routine clinical imaging technique, there is still need for improved spatial resolution in a given acquisition time. Undersampled projection reconstruction (PR) techniques maintain spatial resolution with reduced scan times, and the elliptical centric (EC) view order provides high quality arterial phase images without venous contamination. In this work, we present a hybrid elliptical centric–projection reconstruction (EC‐PR) technique to provide spatial resolution improvement over standard EC in a given time. The k‐space sampling was performed by undersampling the periphery of the kY‐kZ phase encoding plane of an EC view order in a PR like manner. The sampled views were maintained on a rectilinear grid, and thus reconstructed by standard 3DFT. The non‐sampled views were compensated either by zero‐filling or performing a 2D homodyne reconstruction. Compared to a fully sampled k‐space, the EC‐PR sequence acquired in the same scan time provides a resolution improvement of about two, as shown by point spread function analysis and phantom experiments. The hypothesis that EC‐PR provides improved resolution while retaining diagnostically adequate SNR was tested in 11 CE‐MRA studies of the popliteal and carotid arteries and shown to be true (P < 0.03). Magn Reson Med 55:000–000, 2006. © 2005 Wiley‐Liss, Inc.
Requirements for room temperature shimming of the human brain
Authors: Clare Stuart , Evans John , Jezzard Peter 
Published: November 2005

AbstractRoom temperature (RT) shims are used routinely in MRI to remove global and local B0 field inhomogeneity introduced by the subject. Most clinical scanners use only second‐order spherical harmonic terms, but with the increasing availability of very high field systems, third‐ and fourth‐order terms are a serious consideration. However, choosing appropriate coil strengths is of critical importance in shim coil design since overspecification of the shim strengths can lead to a variety of problems, including shim coil self‐resonance. In this study B0 field map data collected over a period of 6 months (over 400 brain volumes) were analyzed to find the characteristic B‐fields required to shim these brains. These data can be used to specify the coil requirements to effectively shim the human brain. Magn Reson Med, 2006. © 2005 Wiley‐Liss, Inc.
Fast perfusion measurements in rat skeletal muscle at rest and during exercise with single‐voxel FAIR (flow‐sensitive alternating inversion recovery)
Authors: Pohmann Rolf , Künnecke Basil , Fingerle Jürgen , Kienlin Markus von 
Published: November 2005

AbstractNon‐invasive measurement of perfusion in skeletal muscle by in vivo magnetic resonance remains a challenge due to its low level and the correspondingly low signal‐to‐noise ratio. To enable accurate, quantitative, and time‐resolved perfusion measurements in the leg muscle, a technique with a high sensitivity is required. By combining a flow‐sensitive alternating inversion recovery (FAIR)‐sequence with a single‐voxel readout, we have developed a new technique to measure the perfusion in the rat gastrocnemius muscle at rest, yielding an average value of 19.4 ± 4.8 mL/100 g/min (n = 22). In additional experiments, perfusion changes were elicited by acute ischemia and reperfusion or by exercise induced by electrical, noninvasive muscle stimulation with varying duration and intensity. The perfusion time courses during these manipulations were measured with a temporal resolution of 2.2 min, showing increases in perfusion of a factor of up to 2.5. In a direct comparison, the results agreed closely with values found with microsphere measurements in the same animals. The quantitative and noninvasive method can significantly facilitate the investigation of atherosclerotic diseases and the examination of drug efficacy. Magn Reson Med, 2006. © 2005 Wiley‐Liss, Inc.
Rapid mapping of flow velocity using a new PARSE method
Authors: Zuo Jin , Walsh Edward G. , Deutsch Georg , Twieg Donald B. 
Published: November 2005

AbstractA new method for flow velocity mapping is presented here. Instead of the conventional approach of employing two images (velocity sensitive and control) to generate velocity information, in the new method one determines the velocity directly from a single‐shot acquisition by solving an inverse problem. This technique is a variant of single‐shot parameter assessment by retrieval from signal encoding (SS‐PARSE). The results of simulation and phantom studies show strong agreement with the actual velocities. The prototype method can measure velocities in the range of –50 to 50 cm/s, which is roughly appropriate for future applications in dynamic blood flow measurement in carotid arteries. Magn Reson Med, 2006. © 2005 Wiley‐Liss, Inc.
Satellite cell numbers in young and older men 24 hours after eccentric exercise
Authors: Dreyer Hans C. , Blanco Cesar E. , Sattler Fred R. , Schroeder E. Todd , Wiswell Robert A. 
Published: November 2005

AbstractWe tested the hypothesis that the expansion of satellite cell numbers, 24 h after maximal eccentric knee extensor exercise, is blunted in older men. Muscle biopsies were obtained from the vastus lateralis of 10 young (23–35 years) and 9 older (60–75 years) men. Satellite cells were identified immunohistochemically using an antibody to neural cell adhesion molecule. After 92 maximal eccentric contractions, the mean number of satellite cells per muscle fiber increased to a greater extent among the young men (141%; P < 0.001) than older men (51%; P = 0.002) from preexercise levels. Similar results were obtained when satellite cells were expressed as a proportion of all sublaminar nuclei. We conclude that a single bout of maximal eccentric exercise increases satellite cell numbers in both age groups, with a significantly greater response among the young men. These data suggest that age‐related changes in satellite cell recruitment may contribute to muscle regeneration deficits among the elderly. Muscle Nerve 2006
Creativity, celebration and play at the Bauhaus, Berlin, 1920: lessons from history for contemporary marketers and arts organizations
Authors: Minahan Stella , Härtel Charmine 
Published: November 2005

Abstract

Organizations can be seen as rigid, rewarding conformity not creativity. Managing the creative team or individual can be challenging. This paper contributes to this special issue of the International Journal of Nonprofit and Voluntary Sector Marketing by addressing ways to manage creativity in an organization, as well as to creatively market the organization. It presents a case study of an organization based in Germany in the 1920s, the Bauhaus. This art and craft organization achieved extraordinary creative output in just over a decade of operation, during the devastation of post World War I. This paper demonstrates how its leader managed the creativity of the staff and students and creatively marketed the organization despite a lack of funds and the desperate shortage of resources. The Bauhaus provides a key lesson for contemporary marketers and managers in developing the characteristics of organizations that nurture creativity and the creative individual.

Copyright © 2005 John Wiley & Sons, Ltd.
Distribution of degrees of polymerization in statistically branched polymers with tetrafunctional branch points: model calculations
Authors: Netopilík Miloš , Kratochvíl Pavel 
Published: November 2005

AbstractStockmayer's classical theory of statistical branching of polymers, as modified by Thurmond and Zimm, and subsequently by Kilb, has been used to describe the evolution of the distribution of the degrees of polymerization with conversion up to the gel point in the copolymerization of a vinyl monomer with a small amount of a divinyl monomer. The weight fractions of molecules with a particular number of branch points per molecule, the averages of the degrees of polymerization of these molecules, and some other characteristics were calculated as functions of a complex variable—the branching parameter γ, including the composition of the monomer mixture, relative reactivities of the individual types of double bonds, and conversion. From these calculations, a few general conclusions on the behaviour of the model system can be drawn. The conclusions are likely to be qualitatively valid also for systems not strictly conforming to the model. Copyright © 2005 Society of Chemical Industry
Precise synthesis of porphyrin array scaffolding polyisocyanides
Authors: Takei Fumie , Kodama Daisuke , Nakamura Sugiko , Onitsuka Kiyotaka , Takahashi Shigetoshi 
Published: November 2005

AbstractAryl isocyanides bearing free‐base and metallo‐porphyrins were prepared and polymerized with a Pd–Pt μ‐ethynediyl complex as the initiator to give polymers with narrow polydispersity indices. The molecular weights of the resulting polymers were precisely controlled by the initial feed ratio of the porphyrin monomer to the initiator. The UV–VIS spectra suggested that the porphyrin pendants are regularly arranged to form stacked columns. Metallo‐porphyrin polymers were also prepared by reacting free‐base porphyrin polymers with metal salts. The successive reactions of free‐base and zinc‐porphyrin monomers resulted in the formation of diblock polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 585–595, 2006
Synthesis and characterization of model 3‐miktoarm star copolymers of poly(dimethylsiloxane) and poly(2‐vinylpyridine)
Authors: Fragouli Panagiota G. , Iatrou Hermis , Hadjichristidis Nikos , Sakurai Takuro , Hirao Akira 
Published: November 2005

Abstract3‐Miktoarm star copolymers, 3μ‐D2V, with two poly(dimethylsiloxane) (PDMS) and one poly(2‐vinylpyridine) (P2VP) arm, were synthesized by using anionic polymerization–high vacuum techniques and (chloromethylphenylethyl)methyl dichlorosilane, heterofunctional linking agent, with two SiCl groups and one CH2Cl group. The synthetic strategy involves the selective reaction of the two SiCl groups with PDMSOLi living chains, followed by reaction of the remaining chloromethyl group with P2VPLi. Combined molecular characterization results (size exclusion chromatography, membrane osmometry, and 1H NMR spectroscopy) revealed a high degree of structural and compositional homogeneity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 614–619, 2006
Synthesis and characterization of polyurethanes from epoxidized methyl oleate based polyether polyols as renewable resources
Authors: Lligadas G. , Ronda J. C. , Galià M. , Biermann U. , Metzger J. O. 
Published: November 2005

AbstractOligomeric polyether polyols were obtained through the acid‐catalyzed ring‐opening polymerization of epoxidized methyl oleate and the subsequent partial reduction of ester groups to give primary alcohols. The oligomers were characterized with titration, spectroscopic techniques (Fourier transform infrared and nuclear magnetic resonance), matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, size exclusion chromatography, and differential scanning calorimetry. Depending on the degree of reduction, polyols of different hydroxyl content values were obtained and were reacted with 4,4′‐methylenebis(phenyl isocyanate) to yield polyurethanes. These materials, which were characterized by differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis, could behave as hard rubbers or rigid plastics. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 634–645, 2006
Large‐scale survey for potentially targetable indels in bacterial and protozoan proteins
Authors: Cherkasov Artem , Lee Shang‐Jung , Nandan Devki , Reiner Neil E. 
Published: November 2005

AbstractOur previous results demonstrated that some essential, housekeeping proteins from pathogenic microorganisms may contain sizable insertions–deletions in their sequences (compared to close human homologs) that can be responsible for unexpected virulence properties. For example, we found that indel‐bearing elongation factor‐1α from several pathogenic protozoa can activate a human tyrosine phosphatase SHP‐1 leading to deactivation of macrophages. On the one hand, these findings allowed development of a strategy for targeting some indel‐containing pathogen proteins that have similar human counterparts. On the other hand, the results raised numerous questions regarding the nature and implications of sequence indels in pathogen proteins. In the present study, we conducted a large‐scale survey of indels in proteins from 136 bacterial and protozoan genomes. It has been established that sizable insertions and deletions occur in approximately 5–10% of bacterial proteins with close human homologs, while proteins from the protozoan pathogens such as Trypanosoma cruzi, Plasmodium falciparum, and Leishmania donovani exhibit elevated indel content that can reach up to 25%. The finding suggested that the occurrence of sequence indels may be involved in the evolution of pathogenic mechanisms in these protozoa. Proteins 2006. © 2005 Wiley‐Liss, Inc.
Modeling truncated hemoglobin vibrational dynamics
Authors: Marsella Luca 
Published: November 2005

AbstractWe present a study on the near equilibrium dynamics of two small proteins in the family of truncated hemoglobins, developed under the framework of a Gaussian network approach. Effective beta carbon atoms are taken into account besides Cαs for all residues but glycines in the coarse‐graining procedure, without leading to an increase in the degrees of freedom (β Gaussian Model). Normalized covariance matrix and deformation along slowest modes with collective character are analyzed, pointing out anticorrelations between functionally relevant sites for the proteins under study. In particular, we underline the functional motions of an extended tunnel‐cavity system running inside the protein matrix, which provide a pathway for small ligands binding with the iron in the heme group. We give a rough estimate of the order of magnitude of the relaxation times of the slowest two overdamped modes and compare results with previous studies on globins. Proteins 2006. © 2005 Wiley‐Liss, Inc.
The thermal adaptation of the nitrogenase Fe protein from thermophilic Methanobacter thermoautotrophicus
Authors: Sen Sanchayita , Peters John W. 
Published: November 2005

AbstractThe nitrogenase Fe protein is a key component of the biochemical machinery responsible for the process of biological nitrogen fixation. The Fe protein is a member of a class of nucleotide‐binding proteins that couple the binding and hydrolysis of nucleoside triphosphates to conformational changes. The nucleotide‐dependent conformational changes modulate the formation of a macromolecular complex, and some members of the class include Gα, EF‐Tu, and myosin. The members of this class are highly interesting model systems for the analysis of aspects of thermal adaptability, since their mechanisms involve protein conformational change and protein–protein interactions. In this study, we have used our extensive knowledge of the structure of the Azotobacter vinelandii nitrogenase Fe protein in multiple structural conformations, and standard homology modeling approaches have been used to generate reliable models of the Fe protein from thermophilic Methanobacter thermoautotrophicus in the analogous structural conformations. The resulting structural comparison reveals that thermal adaptation of the M. thermoautotrophicus Fe protein is conferred by a number of factors, including increased structural rigidity that results from various structural changes within the protein interior. The analysis of hypothetical docking models and nitrogenase complex structures provides insights into the thermal adaptation of the protein–protein interactions that support macromolecular complex formation and catalysis at higher temperatures. Proteins 2006. © 2005 Wiley‐Liss, Inc.
Side‐chain entropy effects on protein secondary structure formation
Authors: Chellgren Brian W. , Creamer Trevor P. 
Published: November 2005

AbstractLoss of conformational entropy is one of the primary factors opposing protein folding. Both the backbone and side‐chain of each residue in a protein will have their freedom of motion restricted in the final folded structure. The type of secondary structure of which a residue is part will have a significant impact on how much side‐chain entropy is lost. Side‐chain conformational entropies have previously been determined for folded proteins, simple models of unfolded proteins, α‐helices, and a dipeptide model for β‐strands, but not for polyproline II (PII) helices. In this work, we present side‐chain conformational estimates for the three regular secondary structure types: α‐helices, β‐strands, and PII helices. Entropies are estimated from Monte Carlo computer simulations. β‐Strands are modeled as two structures, parallel and antiparallel β‐strands. Our data indicate that restraining a residue to the PII helix or antiparallel β‐strand conformations results in side‐chain entropies equal to or higher than those obtained by restraining residues to the parallel β‐strand conformation. Side‐chains in the α‐helix conformation have the lowest side‐chain entropies. The observation that extended structures retain the most side‐chain entropy suggests that such structures would be entropically favored in unfolded proteins under folding conditions. Our data indicate that the PII helix conformation would be somewhat favored over β‐strand conformations, with antiparallel β‐strand favored over parallel. Notably, our data imply that, under some circumstances, residues may gain side‐chain entropy upon folding. Implications of our findings for protein folding and unfolded states are discussed. Proteins 2006. © 2005 Wiley‐Liss, Inc.