bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared Linear Dichroism of Polymers
Authors: Buffeteau Thierry , Pézolet Michel 
Published: June 2007

Abstract

The absorption of linearly polarized infrared radiation by oriented samples is sensitive to the state of polarization of the incident radiation. This phenomenon is known as the
infrared linear dichroism
(IRLD). The degree of optical anisotropy in oriented samples can be characterized by measuring two spectra using light polarized parallel and perpendicular to a reference direction. In this chapter, the theoretical expressions allowing the quantitative determination of molecular orientation from IRLD measurements for systems showing both uniaxial and biaxial symmetry of orientation are described. In addition, typical examples of the use of IRLD to determine the orientation of polymers are presented. These results were obtained from either static measurements or dynamic measurements using a rotating polarizer, a photoelastic modulator (PM‐IRLD) or ultrarapid scanning‐Fourier transform infrared (URS‐FTIR). The use of these techniques allows one to follow the kinetics of orientation over different timescales down to 40 min.
Vibrational Spectroscopy of Conducting Polymers: Theory and Perspective
Authors: Zerbi Giuseppe 
Published: June 2007

Abstract
The sections in this article are

Introduction

Why New Science and Innovative Technology with Polyconjugated Systems?

The World of π Electrons

The Theoretical Approach to Molecular Vibrations of Polyconjugated Molecules

Electron Phonon Coupling

AB
Initio Calculations

Polyacetylene

The Use of

IR

in the Case of Cis and Trans Pristine

PA

The Use of
R
aman Spectra of Polyenes and Trans

PA

Vibrational Spectroscopy of Doped and Photoexcited Trans

PA

Doping

Photoexcitation

From

PA

to Larger Systems: Polyaromatic Molecules

General Aspects

A Detailed Spectroscopic Analysis of Simple Linear Polyaromatic Chains

Doping

Photoexcitation

Photochromic Polymers

Molecular

NLO

Properties from Vibrational Spectra of Polyconjugated Molecules

What's Next? A New Window Opens

Acknowledgments
Synthesis functional poly(carbonate‐b‐ester) copolymers and micellar characterizations
Authors: Chiu Fang‐Chyou , Lai Chia‐Sheng , Lee Ren‐Shen 
Published: June 2007

AbstractFunctional poly(carbonate‐b‐ester)s were synthesized in buck by ring‐opening polymerization of the carbonate (TMC, MBC, or BMC) with tert‐butyl N‐(2‐hydroxyethyl) carbamate as an initiator, and then with ε‐CL (or ε‐BCL) comonomer. Subsequently, the PMMC‐b‐PCL with pendent carboxyl groups and the PTMC‐b‐PHCL with pendent hydroxyl groups were obtained by catalytic debenzylation. DSC analysis indicated that only one Tg at an intermediate temperature the Tgs of the two polymer blocks. A decrease Tg was observed when an increase contents of ε‐CL incorporated into the copolymers. In contrast, two increased Tms were observed with increasing PCL content. The block copolymers formed micelle in aqueous phase with critical micelle concentrations (cmcs) in the range of 2.23–14.6 mg/L and with the mean hydrodynamic diameters in the range of 100–280 nm, depending on the composition of copolymers. The drug entrapment efficiency and hydrolytic degradation behavior of micelle were also evaluated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Order from chaos: The poetics and pragmatics of scientific recordkeeping
Authors: Shankar Kalpana 
Published: June 2007

AbstractAlthough the production of laboratory and field records is fundamental to the conduct of contemporary science, there has been little research into this topic in information studies. This article reports on a study in which, using ethnographic methods, the author studied recordkeeping as it is practiced in a basic research science laboratory. The process by which the record is created to reflect both personal need and professional norms is framed as a series of acts of selection, synthesis, and standardization. The article concludes with reflections on the role of deep understanding of scientific recordkeeping for other disciplines and the design of digital laboratory technologies.
Democratic theory in library information science: Toward an emendation
Authors: Buschman John 
Published: June 2007

AbstractDespite quantities of popular rhetoric, democratic theory holds an aposiopetic place within library and information science (LIS) in both senses of that word: It is both in a stasis holding to basic ideas outlined 200 years ago and also a silence largely maintained. A review of a number of state‐of‐the‐literature reviews make the case that it has not been systematically explored or applied, and most LIS work elides the questions democratic theory raises. It is time to emend this and account for a relevant intellectual source which can more firmly ground LIS practice and research in normative terms. Toward that end, three productive wellsprings of democratic theory are reviewed: Jürgen Habermas, Sheldon Wolin, and those working on democratic education (Amy Gutmann, Richard Brosio, Maxine Greene). The article concludes with an outline of some possible LIS questions and approaches drawn from these democratic theorists.
Safeguarding young people from cyber pornography and cyber sexual predation: a major dilemma of the internet
Authors: Dombrowski Stefan C. , Gischlar Karen L. , Durst Theo 
Published: June 2007

AbstractOver the past 20 years, the internet has provided an expedient mode of communication and access to a wealth of information. The internet is a valuable tool; however, it can also be detrimental to the wellbeing of children due to numerous online hazards. There is the potential for children to be abused via cyberspace through online sexual solicitation and access to pornography. Indeed, the internet is replete with inappropriate material, including pornography, chatrooms with adult themes and access to instant messaging wherein others could misrepresent themselves. Because children are actively utilizing the internet where unknown others can have access to them or where they can be exposed to inappropriate sexual materials, they require safeguarding and education in safe internet use. The purpose of this article is to provide a discussion of how to safeguard children from and educate them about online sexual solicitation and pornography. We contend that society needs an overall conceptual shift in its attitude towards young people's internet use. Copyright © 2007 John Wiley & Sons, Ltd.
Developing interprofessional relationships: tapping the potential of inter‐agency training
Authors: Glennie Sara 
Published: June 2007

AbstractThe creation of effective Local Safeguarding Children Boards in England and Wales is contingent upon the development of new interprofessional partnerships amongst practitioners, managers and strategic planners. Inter‐agency training will have a role to play in facilitating partnership development throughout an increasingly complex inter‐agency system. The following article reviews the recent history of inter‐agency training and the increasing clarity regarding its distinctive purpose. It highlights three theoretical frameworks that have been influential in the development of ideas about the most appropriate focus and process when working across organisational and professional boundaries. Finally, attention is drawn to an emerging consensus as to the core dimensions of effectiveness in interprofessional working relationships. Copyright © 2007 John Wiley & Sons, Ltd.
Face‐Selective [2]‐ and [3]Rotaxanes: Kinetic Control of the Threading Direction of Cyclodextrins
Authors: Oshikiri Tomoya , Takashima Yoshinori , Yamaguchi Hiroyasu , Harada Akira 
Published: June 2007

AbstractNew [2]‐ and [3]pseudorotaxanes containing α‐cyclodextrin (α‐CDs) molecules as rotors and alkyl pyridinium derivatives as axles were prepared by a slipping process. The inclusion behavior of these rotaxanes was investigated by using one‐ and two‐dimensional NMR spectroscopy. The methyl group at the 2‐position of the pyridinium moiety at the end of each axle molecule was found to control the rates of threading of the α‐CD onto the axle molecules. α‐CD can approach axle molecules from a particular direction to form inclusion complexes. Axle molecules that contain a 2‐methylpyridinium moiety at one end and a bulky stopper at the other end can regulate the direction of approach to give a [2]pseudorotaxane such as 2 b–α‐CD. A [3]pseudorotaxane in which two α‐CD molecules are arranged facing in the same direction at two stations of the tetracationic axle molecule was also obtained. These face‐selective behaviors are dominated by kinetic processes rather than thermodynamic processes.
Artificial Ditopic Arg‐Gly‐Asp (RGD) Receptors
Authors: Schmuck Carsten , Rupprecht Daniel , Junkers Matthias , Schrader Thomas 
Published: June 2007

AbstractCovalent fusion of two artificial recognition motifs for arginine and aspartate resulted in a new class of ditopic RGD receptor molecules, 1–4. The two binding sites for the oppositely charged amino acid residues are linked by either flexible linkers of different length (in 1–3) or a rigid aromatic spacer (in 4). These spacers are shown to be critical for the complexation efficiency of the artificial hosts. If the linkers are too flexible, as in 1–3, an undesired intramolecular self‐association occurs within the host and competes with, and thereby weakens, substrate binding. The rigid aromatic linker in 4 prevents any intramolecular self‐association and hence efficient RGD binding is observed, even in buffered water (association constant of Ka≈3000 m−1). A further increase in hydrophobic contacts, as in host 16, can complement the specific Coulomb attractions, thereby leading to an even more stable complex (Ka=5000 m−1). The recognition events have been studied with NMR spectroscopy, UV/Vis spectroscopy, and fluorescence titrations.
An actin‐stabilizing peptide conjugate deduced from the major outer sheath protein of the bacterium Treponema denticola
Authors: Amin Mohsen , Grove David A. , Kapus András , Glogauer Michael , Ellen Richard P. 
Published: June 2007

AbstractA synthetic peptide conjugated to bovine serum albumin, P34BSA, based on a 10‐mer in the deduced amino acid sequence of the major outer sheath protein of Treponema denticola, was found to stabilize actin filaments of fibroblasts. Pretreatment of cells with P34BSA inhibited the actin disruption induced by cytochalasin D and latrunculin B. P34BSA was taken up by the cells and localized among actin filaments. P34BSA bound actin from fibroblast lysates, and cell exposure to P34BSA led to the activation of RhoA, a key regulator of actin filament assembly in fibroblasts. Exposure of fibroblasts to P34BSA retarded their migration on a collagen substratum. P34BSA also inhibited chemotaxis of murine neutrophils. Our findings with a novel peptide conjugate imply that bacterial proteins known to perturb the cytoskeleton represent a rich source of molecular models upon which to design synthetic reagents for modulating actin‐dependent cellular functions. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
The contributions of microtubule stability and dynamic instability to adenovirus nuclear localization efficiency
Authors: Warren James C. , Cassimeris Lynne 
Published: June 2007

AbstractAdenoviruses (Ads) utilize host cell microtubules to traverse the intracellular space and reach the nucleus in a highly efficient manner. Previous studies have shown that Ad infection promotes the formation of stable, posttranslationally modified microtubules by a RhoA‐dependent mechanism. Ad infection also shifts key parameters of microtubule dynamic instability by a Rac1‐dependent mechanism, resulting in microtubules with lower catastrophe frequencies, persistent growth phases, and a bias toward net growth compared to microtubules in uninfected cells. Until now it was unclear whether changes in RhoGTPase activity or microtubule dynamics had a direct impact on the efficiency of Ad microtubule‐dependent nuclear localization. Here we have performed synchronous Ad infections and utilized confocal microscopy to analyze the individual contributions of RhoA activation, Rac1 activation, microtubule stability, dynamic behavior, and posttranslational modifications on Ad nuclear localization efficiency (NLE). We found that drug‐induced suppression of microtubule dynamics impaired Ad NLE by disrupting the radial organization of the microtubule array. When the microtubule array was maintained, the suppression or enhancement of microtubule turnover did not significantly affect Ad NLE. Furthermore, RhoA activation or the formation of acetylated microtubules did not enhance Ad NLE. In contrast, active Rac1 was required for efficient Ad nuclear localization. Because Rac1 mediates persistent growth of microtubules to the lamellar regions of cells, we propose that Ad‐induced activation of Rac1 enhances the ability of microtubules to “search and capture” incoming virus particles. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
Performance of calibration standards for antigen quantitation with flow cytometry in chronic lymphocytic leukemia
Authors: Rossmann Eva D. , Lenkei Rodica , Lundin Jeanette , Mellstedt Håkan , Österborg Anders 
Published: June 2007

AbstractBackground:The fluorescence intensities of CD3, CD4 on T cells and CD20, CD22 molecules on B cells were quantitatively measured on lymphocytes from chronic lymphocytic leukemia (CLL) patients and healthy donors.Methods:The performance of three different types of microbeads was compared, i.e. Quantum molecules of equivalent soluble fluorochrome (Q‐MESF), Quantum simply cellular (QSC), and QuantiBRITE™ (QB). As all PE‐conjugates had a F/P ratio of 1:1, the MESF units represented also the antibody binding capacity (ABC).Results:The ABCs of CD4 and CD20 antigens estimated with QSC (ABCQSC) were higher than those assigned with QB (ABCQB) with an average difference 49%. Higher numbers of antigenic sites were obtained with Q‐MESF than with QSC for CD20 antigen. On the contrary, CD4 antigenic sites numbers estimated with QSC were higher than those estimated with Q‐MESF. ABC values estimated with Quantum MESF PE (ABCQ‐MESF) were ∼15% higher than ABCQSC, whereas ABCQ‐MESF was ∼49% higher than ABCQB. Statistically significant correlations were found between the values obtained using various standards. The present study is the first to report down‐regulation of CD3 antigen on T cells from patients with CLL.Conclusions:This study emphasizes the relevance of quantitative measurement of fluorescence intensity by flow cytometry as a standardized approach to measure and interpret the expression of some CLL markers and reduce variability of results obtained at different sites in multi‐center clinical studies. © 2007 Clinical Cytometry Society
Impairment of dendritic cell function by excretory‐secretory products: A potential mechanism for nematode‐induced immunosuppression
Authors: Segura Mariela , Su Zhong , Piccirillo Ciriaco , Stevenson Mary M. 
Published: June 2007

AbstractTo determine whether helminth‐derived products modulate dendritic cell (DC) function, we investigated the effects of excretory‐secretory products (ES) and adult worm homogenate (AWH) derived from the gastrointestinal nematode Heligmosomoides polygyrus (Hp) on murine bone marrow‐derived DC (BMDC). Compared to the TLR9 ligand CpG, Hp‐derived products alone failed to induce DC activation. ES, but not AWH, inhibited BMDC cytokine and chemokine production and co‐stimulatory molecule expression (CD40, CD86 and MHC class II) induced by TLR ligation. TLR ligand‐independent, PMA‐induced DC activation was unaffected by ES. Recipients of ES‐treated BMDC pulsed with OVA had suppressed Ab responses in vivo, irrespective of the Th1 or Th2 isotype affiliation, compared to recipients of control OVA‐pulsed BMDC. Importantly, suppression occurred even in the presence of the potent type 1 adjuvant CpG. In contrast to untreated OVA‐pulsed BMDC, ES‐treated BMDC pulsed with OVA had reduced co‐stimulatory molecule and cytokine expression. CD4+CD25+Foxp3– T cells, which secreted high IL‐10 levels, were generated in co‐cultures of OT‐II OVA‐specific TCR‐transgenic CD4+ T cells and ES‐treated BMDC. These IL‐10‐secreting T cells suppressed effector CD4+ T cell proliferation and IFN‐γ production, the latter effect mediated by an IL‐10‐dependent mechanism. Together, these results demonstrate that nematode ES impaired DC function and suppressed both Th1 and Th2 adaptive immune responses possibly by inducing regulatory T cells.
Expansion and activation of CD4+CD25+ regulatory T cells in Heligmosomoides polygyrus infection
Authors: Finney Constance A. M. , Taylor Matthew D. , Wilson Mark S. , Maizels Rick M. 
Published: June 2007

AbstractRegulatory T cell responses to infectious organisms influence not only immunity and immunopathology, but also responses to bystander antigens. Mice infected with the gastrointestinal nematode parasite Heligmosomoides polygyrus show an early Th2‐dominated immune response (days 7–14), but by day 28 a strongly regulatory profile is evident with antigen‐specific IL‐10 release and elevated frequency of CD4+ T cells bearing surface TGF‐β. CD4+CD25+ T cells from infected mice show enhanced capacity to block in vitro effector T cell proliferation. CD4+CD25+ cell numbers expand dramatically during infection, with parallel growth of both CD25+Foxp3+ and CD25+Foxp3– subsets. CTLA‐4 and glucocorticoid‐induced tolerance‐associated receptor, also associated with regulatory T cell function, become more prominent, due to both expanded CD25+ cell numbers and increased expression among the CD25– population. Both intensity and frequency of CD103 expression by CD4+ T cells rise significantly, with greatest expansion among CD25+Foxp3+ cells. While TGF‐β expression is observed among both CD25+Foxp3+ and CD25+Foxp3– subsets, it is the latter population which shows higher TGF‐β staining following infection. These data demonstrate in a chronic helminth infection that Foxp3+ regulatory T cells are stimulated, increasing CD103 expression in particular, but that significant changes occur to other populations including expansion of CD25+TGF‐β+Foxp3– cells, and induction of CTLA‐4 on CD25– non‐regulatory lymphocytes.
In Pursuit of an Acetylenedithiolate Synthesis
Authors: Seidel Wolfram W. , Meel Matthias J. , Schaffrath Markus , Pape Tania 
Published: June 2007

AbstractAcetylene disulfides RSC2SR, which are furnished with typical thiol protection groups R, were synthesized, fully characterized, and tested with respect to the aimed cleavage of R. While the alkyne RSC2SR with R = C2H4SiMe3 is easily accessible, the corresponding disulfide with R = CPh3 can be prepared only with difficulties, and attempts to use the SiMe3 group lead to the isolation of a dithiacyclopentene derivative. The molecular structures of Ph3CSC2SCPh3 and Ph3CSC2H, which were investigated by X‐ray diffraction, show a remarkable combination of long and very short carbon–sulfur single bonds. However, removal of the trityl groups by sodium phenolate or methyllithium in THF led to intractable solutions. In contrast, removal of both trimethylsilylethyl groups in Me3SiC2H4SC2SC2H4SiMe3 with (Bu4N)F in THF proceeded smoothly, if benzyl bromide as the trapping agent is present. Hence, the successful transfer of the C2S22– synthon in solution was proven by isolation of BnSC2SBn.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Conformation of Trisialic Acid Lactone: NMR Spectroscopic Analysis and Molecular Dynamics Simulation
Authors: Chen Chien‐Sheng , Yu Yi‐Ping , Hsu Chun‐Hua , Wu Ying‐Ta , Zou Wei , Fang Jim‐Min , Wu Shih‐Hsiung 
Published: June 2007

AbstractThe conformation of the trisialic acid lactone α2,8‐(NeuAc)3 was analyzed by a combination of NMR spectroscopy, molecular modelling and molecular dynamic (MD) calculations. The interresidue NOEs provided 14 important distance restraints for the molecular simulation, and the final simulated structures showed a root mean square deviation of 0.78 for all superimposed structures. Because of the steric hindrance from the spirobicyclic δ‐lactone, the individual sialic acid pyranose rings are considered essential in the chair 5C2 conformation. In addition, lactone I close to the nonreducing end adopted a half‐chair A2HCB9 conformation, whereas lactone II, which is close to the reducing end adopted a skewed twist‐boat C2SC9 conformation. In the NMR solution structure and in the 1.0‐ns, in‐water MD calculation, the final simulated structures are in the exocyclic torsions (ω7, ω8) = (gauche–anti) surface of the energy adiabatic map, where the global minimum can be found. During the in‐water MD simulation, a slight fluctuation in the structure was observed, reflecting the steady conformation of the lactone and the middle residue of the trisaccharide. These data are consistent with a theoretical approach of polysialic acid (PSA) polylactone with torsions (ω7, ω8) = (65°, 175°) and (Φ, Ψ) = (75.8°, –112.4°). Thus, we conclude that the PSA polylactone is a right‐hand helix with a rotation angle, μ, of 240° and a repeating unit, n, of 1.5 residues. The structural properties of the PSA lactone discussed within this context differ from the helical epitope of G2+ PSA and may serve in future PSA‐related antigen designs. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Chiral Concave Imidazolinium Salts as Precursors to Chiral Concave N‐Heterocyclic Carbenes
Authors: Winkelmann Ole , Linder David , Lacour Jérôme , Näther Christian , Lüning Ulrich 
Published: June 2007

AbstractImidazolinium moieties have been incorporated into bimacrocycles to generate precursors for concave N‐heterocyclic carbenes (NHCs). By using one symmetrically substituted benzene bridgehead and one naphthalene bridgehead devoid of local C2‐symmetry, axially chiral concave imidazolinium ions have been obtained. Starting from 2,7‐dihydroxy‐1‐nitronaphthalene (7), the phenol groups have been transformed to 4‐pentenyl ethers 8, and the nitro group was then reduced to the corresponding amine 9. Next, 9 and a 2,6‐bis(alkenyloxy)aniline 10 were connected by an oxalic acid linker. After reduction of the diamide 13 to diamine 14, a bridge was installed with triethyl orthoformate to give a tetraalkenyl‐substituted imidazolinium salt 15. Ring‐closing metathesis of 15 followed by hydrogenation of the products 16 yielded the bimacrocyclic salts 17 in 9–18 % overall yield (based on 7), giving amounts up to >300 mg. The configurational stability of 17 was investigated by NMR using chiral enantiopure anions TRISPHAT 18 and BINPHAT 19 as stereodynamic probes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
N1–C4 β‐Lactam Bond Cleavage in the 2‐(Trimethylsilyl)thiazole Addition to β‐Lactam Aldehydes: Asymmetric Synthesis of Spiranic and Tertiary α‐Alkoxy‐γ‐keto Acid Derivatives
Authors: Alcaide Benito , Almendros Pedro , Redondo María C. 
Published: June 2007

AbstractStarting substrates, enantiopure spiranic or 3‐substituted 3‐alkoxy‐4‐oxoazetidine‐2‐carbaldehydes, were prepared from (R)‐2,3‐O‐isopropylideneglyceraldehyde derived azetidine‐2,3‐diones by sequential Barbier‐type addition reactions followed by hydroxy functionalization and aldehyde unmasking. The reaction between the above β‐lactam aldehydes and 2‐(trimethylsilyl)thiazole (TMST) gave as major products conformationally constrained α‐alkoxy‐γ‐keto amides, which can be considered both as aldols as well as Passerini‐type products, by N1–C4 β‐lactam bond cleavage. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)