bluuebunny/crossref_metadata_2025_split huggingface dataset:
Freeze‐Quench Kinetics
Authors: de Vries Simon 
Published: March 2008

AbstractRapid‐mixing, rapid‐freezing techniques are employed for the study of enzyme or chemical catalytic mechanisms. The techniques aim to provide electronic and molecular structures of transient intermediates formed during the reaction by means of spectroscopic analyses of the rapidly frozen samples. Briefly, the mixing‐sampling procedure consists of the rapid mixing of two reactants, for example, enzyme and substrate, followed by rapid freezing of the mixture in a liquid cryo‐medium or on a cold plate to quench the reaction progress. The resulting frozen powder is subsequently sampled and made available for further low‐temperature spectroscopic analyses such as UV‐Vis spectroscopy, multifrequency Electron Paramagnetic Resonance (EPR) spectroscopy, Electron Nuclear Double Resonance (ENDOR) spectroscopy, Electron Spin Echo Envelope Modulation (ESEEM), Magnetic Circular Dichroïsm (MCD) spectroscopy, Mössbauer spectroscopy, resonance Raman spectroscopy, or X‐ray Absorption Spectroscopy. By preparing a series of samples freeze‐quenched after various times, a full kinetic profile of the catalytic cycle of an enzyme or any other chemical reaction is obtained. The structures of intermediates are assigned in conjunction with (a selection of) the spectroscopic techniques listed above.This article details various aspects of continuous‐flow and stopped‐flow rapid‐mixing techniques, considering mixer design, freeze‐quenching methodology, and sampling. The scope and limitations to (bio)chemical research of the well‐established rapid freeze‐quench (RFQ) and the recently developed microsecond freeze‐hyperquenching (MHQ) technologies are specifically highlighted.
Perspective‐driven text comprehension
Authors: Kaakinen Johanna K. , Hyönä Jukka 
Published: March 2008

AbstractThe present article reports results of an eye‐tracking experiment, which examines whether the perspective‐driven text comprehension framework applies to comprehension of narrative text. Sixty‐four participants were instructed to adopt either a burglar's or an interior designer's perspective. A pilot test showed that readers have more overlapping prior knowledge with the burglar‐relevant than with the interior designer‐relevant information of the experimental text. Participants read either a transparent text version where the (ir)relevance of text segments to the perspective was made apparent, or an opaque text version where no direct mention of the perspective was made. After reading participants wrote a free recall of the text. The results showed that perspective‐related prior knowledge modulates the perspective effects observed in on‐line text processing and that signalling of (ir)relevance helps in encoding relevant information to memory. It is concluded that the proposed framework generalizes to the on‐line comprehension of narrative texts. Copyright © 2008 John Wiley & Sons, Ltd.
The acquisition of document search strategies in grade school students
Authors: Rouet Jean‐François , Coutelet Béatrice 
Published: March 2008

AbstractSkilled comprehension includes the ability to search complex documents in order to retrieve and make use of information of interest. Two studies investigated the acquisition of document search skills by 9‐ to 13‐year‐old students. Experiment 1 explored third, fifth and seventh grade students' book search strategies as a function of question complexity. There was a sharp decrease across grades in time on task and need for experimenter assistance. Older students' search strategies evolved from mere flipping through the pages to top‐down search based on the use of structural organizers, for example the table of contents and index. Experiment 2 replicated the effects of grade on text search strategies using a more controlled setting. Older students were significantly faster at searching longer texts, and they used more top‐down strategies based on the use of text organizers. We discuss the contribution of metatextual knowledge and self‐regulation in expert text processing strategies. Copyright © 2008 John Wiley & Sons, Ltd.
Advances in text comprehension: model, process and development
Authors: Verhoeven Ludo , Perfetti Charles 
Published: March 2008

AbstractTo a very large extent, children learn in and out of school from written text. Information Communications Technologies (ICT) offers many possibilities to facilitate learning by confronting children with multimodal texts. In order to be able to implement learning environments that optimally facilitate children's learning, insight is needed into the cognitive processes underlying text comprehension. In this light, the aim of this special issue is to report on new advances in text comprehension research in perspective of educational implications. Starting from recent theoretical frameworks on the cognitive processes underlying text comprehension, the online processing of text will be discussed in adults and in school children. Copyright © 2008 John Wiley & Sons, Ltd.
Gd2O(CO3)2 · H2O Particles and the Corresponding Gd2O3: Synthesis and Applications of Magnetic Resonance Contrast Agents and Template Particles for Hollow Spheres and Hybrid Composites
Authors: Li I‐Fang , Su Chia‐Hao , Sheu Hwo‐Shuenn , Chiu Hui‐Chi , Lo Yi‐Wei , Lin Wei‐Ting , Chen Jyh‐Horng , Yeh Chen‐Sheng 
Published: March 2008

AbstractThe solution approach was employed to yield multifunctional amorphous Gd2O(CO3)2 · H2O colloidal spheres by reflux of an aqueous solution containing GdCl3 · 6H2O and urea. By elongating the reaction time, crystalline rhombus‐ shaped Gd2O(CO3)2 · H2O with at least 87% yield could be formed and were also accompanied by some rectangular particles. High‐resolution synchrotron powder X‐ray diffraction provides crystal structure information, such as cell dimensions, and indexes the exact crystal packing with hexagonal symmetry, which is absent from the Joint Committee on Powder Diffraction Standards file, for the crystalline rhombus sample. Particle formation was studied based on the reaction time and the concentration ratio of [urea]/[GdCl3 · 6H2O]. After a calcination process, the amorphous spheres and crystalline rhombus Gd2O(CO3)2 · H2O particles convert into crystalline Gd2O3 at temperatures above 600 °C. For in vitro magnetic resonance imaging (MRI), both Gd2O(CO3)2 · H2O and Gd2O3 species show the promising T1‐ and T2‐weighted effects and could potentially serve as bimodal T1‐positive and T2‐negative contrast agents. The amorphous Gd2O(CO3)2 · H2O contrast agent further demonstrates enhanced contrast of the liver and kidney using a dynamic contrast‐enhanced MR imaging (DCE‐MRI) technique for in vivo investigation. The multifunctional capability of the amorphous Gd2O(CO3)2 · H2O spheres was also evidenced by the formation of nanoshells using these amorphous spheres as the template. Surface engineering of the amorphous Gd2O(CO3)2 · H2O spheres could be performed by covalent bonding to form hollow silica nanoshells and hollow silica@Fe3O4 hybrid particles.
Incorporation of a Hydrophobic Antibacterial Peptide into Amphiphilic Polyelectrolyte Multilayers: A Bioinspired Approach to Prepare Biocidal Thin Coatings
Authors: Guyomard Aurélie , Dé Emmanuelle , Jouenne Thierry , Malandain Jean‐Jacques , Muller Guy , Glinel Karine 
Published: March 2008

AbstractA non‐water‐soluble natural antibacterial peptide, gramicidin A, has been successfully incorporated into polyelectrolyte assemblies to elaborate biocidal thin films. For this, we used a double strategy, the first step of which consists of complexing the peptide by a non‐denaturing anionic amphiphilic polysaccharide, namely a hydrophobically modified carboxymethylpullulan. We demonstrate that the use of this amphiphilic anionic derivative allows to efficiently solubilize the peptide in aqueous solution, without denaturation. The amount of peptide solubilized by the amphiphilic polysaccharide was optimized by systematically varying the hydrophobicity and the molar mass of the CMP derivative. In a second step, the negatively charged complex was layer‐by‐layer assembled with cationic poly(L‐lysine) to form biofunctionalized thin films. The amount of peptide incorporated in the multilayers was controlled by changing the number of deposited complex layers, and was quantified by UV spectroscopy. The antibacterial activity of the resulting biofunctionalized films was evidenced against a gram‐positive bacterium, E. faecalis. We demonstrated that the biocidal activity resulted from a double mechanism: contact between bacteria and the film surface, and release of the peptide into the solution surrounding the film. We also showed that the peptide was not completely removed from the film after rinsing, which insured preservation of the biocidal activity of the film surface.
Tetraphenylimidazole‐Based Excited‐State Intramolecular Proton‐Transfer Molecules for Highly Efficient Blue Electroluminescence
Authors: Park Sanghyuk , Seo Jangwon , Kim Se Hun , Park Soo Young 
Published: March 2008

AbstractAiming for highly efficient blue electroluminescence, we have designed and synthesized a novel class of tetraphenylimidazole‐ based excited‐state intramolecular proton‐transfer (ESIPT) molecules with covalently linked charge‐transporting functional groups (carbazole‐ and oxadiazole‐functionalized hydroxyl‐substituted tetraphenylimidazole (HPI), i.e., HPI‐Cbz and HPI‐Oxd, respectively). High Tg (ca. 130 °C) amorphous films of HPI‐Cbz and HPI‐Oxd showed intense and ideal blue‐light emission (λmax = 462 and 468 nm, ΦPL = 0.44 and 0.38) with a large Stokes shift of over 160 nm and a narrow full width at half‐maximum of less than 65 nm. Organic light‐emitting devices using HPI‐Cbz and HPI‐Oxd as the emitting layer generated an efficient blue electroluminescence (EL) emission peaking at around 460 nm with excellent CIE coordinates of (x, y) = (0.15, 0.11). A maximum external quantum efficiency of 2.94%, and a maximum brightness of 1 229 cd m−2 at 100 mA cm−2, as well as a low turn‐on voltage of 4.8 V were achieved in this work.
Hydroxyapatite Modified with Carbon‐Nanotube‐Reinforced Poly(methyl methacrylate): A Nanocomposite Material for Biomedical Applications
Authors: Singh Manoj Kumar , Shokuhfar Tolou , Gracio José Joaquim de Almeida , de Sousa António Carlos Mendes , Fereira José Maria Da Fonte , Garmestani Hamid , Ahzi Said 
Published: March 2008

AbstractThe paper reports on a freeze‐granulation technique to prepare a novel nanocomposite of poly(methyl methacrylate) (PMMA)‐modified hydroxyapatite (HA) with multiwalled carbon nanotubes (MWCNTs) as reinforcement for a new generation biomedical bone cement and implant coatings. By using this technique it is possible to increase material homogeneity and also enhance the dispersion of MWCNTs in the composite matrix. The phase composition and the surface morphology of the nanocomposite material were studied using X‐ray diffraction, field‐emission scanning electron microscopy, and micro‐Raman spectroscopy. Additionally, nanomechanical properties of different concentrations of MWCNT‐reinforced nanocomposite were performed by a nanoindentation technique, which indicates that a concentration of 0.1 wt % MWCNTs in the PMMA/HA nanocomposite material gives the best mechanical properties.
Antimicrobial Gallium‐Doped Phosphate‐Based Glasses
Authors: Valappil Sabeel P. , Ready Derren , Neel Ensanya A. Abou , Pickup David M. , Chrzanowski Wojciech , O'Dell Luke A. , Newport Robert J. , Smith Mark E. , Wilson Michael , Knowles Jonathan C. 
Published: March 2008

AbstractNovel quaternary gallium‐doped phosphate‐based glasses (1, 3, and 5 mol % Ga2O3) were synthesized using a conventional melt quenching technique. The bactericidal activities of the glasses were tested against both Gram‐negative (Escherichia coliandPseudomonas aeruginosa) and Gram‐positive (Staphylococcus aureus, methicillin‐resistantStaphylococcus aureus, andClostridium difficile) bacteria. Results of the solubility and ion release studies showed that these glass systems are unique for controlled delivery of Ga3+.71Ga NMR measurements showed that the gallium is mostly octahedrally coordinated by oxygen atoms, whilst FTIR spectroscopy provided evidence for the presence of a small proportion of tetrahedral gallium in the samples with the highest gallium content. FTIR and Raman spectra also afford an insight into the correlation between the structure and the observed dissolution behaviorviaan understanding of the atomic‐scale network bonding characteristics. The results confirmed that the net bactericidal effect was due to Ga3+, and a concentration as low as 1 mol % Ga2O3was sufficient to mount a potent antibacterial effect. The dearth of new antibiotics in development makes Ga3+a potentially promising new therapeutic agent for pathogenic bacteria includingMRSAandC. difficile.
Unusual Strain Accommodation and Conductivity Enhancement by Structure Modulation Variations in Sr4Fe6O12+δ Epitaxial Films
Authors: Solís Cecilia , Rossell Marta D. , Garcia Gemma , Van Tendeloo Gustaaf , Santiso José 
Published: March 2008

AbstractMixed ionic and electronic conducting (MIEC) films can be applied in solid state electrochemical devices such as oxygen separation membranes for producing pure oxygen, gas sensors or as cathode in solid oxide fuel cells. The current interest in layered perovskite‐related phases, like Sr4Fe6O13 (SFO), arises from their significant oxygen permeability as predicted from theoretical studies. Nevertheless, before any practical application further fundamental study on this fairly unknown oxide is required mainly to assess the mechanisms affecting the transport properties. Epitaxial Sr4Fe6O12+δ (SFO) films of b‐axis orientation with different thicknesses have been prepared by the pulsed laser deposition technique onto different perovskite substrates: SrTiO3, NdGaO3 and LaAlO3. The strain accommodation has been found to vary as a function of film thickness as well as the substrate material causing different type of defects in the film microstructure, as well as variations in the oxygen anion content and ordering. Correspondingly, the total electrical conductivity of the films has been also found to vary significantly as a function of thickness and substrate type showing an unexpected enhancement for strained thin films. The variations in the transport properties are discussed in terms of the different strain accommodation mechanisms and the variation of the modulated structure observed for this compound.
How an energy company takes a human rights approach
Authors: Sherman John 
Published: March 2008

AbstractTwo CPR Fall 2007 Meeting panelists re‐team to expand their focus on corporate social responsibility and its relationship to conflict resolution. First, John Sherman, of Westborough, Mass., describes why his employer, energy provider National Grid, focuses substantial business efforts on giving communities a voice in its efforts. Caroline Rees, of Cambridge, Mass., examines the need for grievance mechanisms to address inevitable local conflicts. Both authors provide practical advice based on adaptable existing models.
Ethylene polymerization by diphenyl ether bridged dinuclear titanocenes/MAO
Authors: Nie Yujing , Sun Junquan , Cheng Jin , Ren Hua , Schumann Herbert 
Published: March 2008

AbstractTwo diphenyl ether bridged dinuclear titanocenes, (C5H5TiCl2)2{[(RC5H3)CH2](p‐C6H4)O(C6H4‐p) [CH2(C5H3R)] [R = H(5), Me(6)] have been synthesized and characterized by 1H‐NMR spectroscopy and elemental analysis. In the presence of methylaluminoxane (MAO), 5 and 6 are efficient catalysts for ethylene polymerization. The influences of the polymerization conditions such as [MAO]/[Cat] molar ratio, catalyst concentration, polymerization temperature and time have been studied in detail. Compounds 5 and 6 produce 105 g polyethylene (PE)/(mol Ti h), which is in the same range as that produced by the binuclear titanocenes {(C5H5TiCl2)2[(C5H4CH2) (p‐C6 H4)(C6H4‐p)(CH2C5H4)]} (7) and (C5H5TiCl2)2(C5H4CH2 CH2OCH2 CH2C5H4) (8). However, the molecular weight of PE is somewhat higher than that of PE using 7 and 8. The high temperature gel permeation chromatography (GPC) results show that the molecular weight distributions of PE produced by 5 and 6 (MWD = 6.17 and 7.56) were obviously broader than those of PE produced by 7 (MWD = 4.28) and 8 (MWD = 5.90). The melting points of the PE produced by 5 and 6 are higher than 132°C, indicating ahighly linear and highly crystalline PE. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
pH‐sensitivity and air/water interfacial activity of poly(N‐isopropylacrylamide‐co‐methacrylic acid‐co‐octadecyl acrylate)
Authors: Choi Jae‐Hyung , Lee Hyeon Youg , Kim Jin‐Chul 
Published: March 2008

AbstractThe copolymers of N‐isopropylacrylamide and methacrylic acid (P(NIPAM‐co‐MAA)), and the copolymers of N‐isopropylacrylamide, methacrylic acid, and octadecyl acrylate (P(NIPAM‐co‐MAA‐co‐ODA)) were synthesized by a free radical reaction. MAA was copolymerized as a pH‐sensitive residue and ODA as a hydrophobic moiety. The transmittances of P(NIPAM‐co‐MAA) solutions were almost constant in the pH 2.0–8.5. On the other hand, the transmittances of P(NIPAM‐co‐MAA‐co‐ODA) solutions were reduced in the pH 2–5, whereas the values were almost invariable in the pH 5.0–8.5. In the low range of pH, most of carboxyl groups are in unionized forms. Therefore, the hydrophobic interactions among ODAs might be greater than the electrostatic repulsions. Self‐assemblies such as polymeric micelles could be formed, leading to the reduced transmittances. In the measurement of air/water interfacial tensions, the surface activities of both P(NIPAM‐co‐MAA) and P(NIPAM‐co‐MAA‐co‐ODA) were lower in alkali pHs than in acidic conditions. This is possibly because that the copolymers are more hydrophilic at higher pHs due to the ionization of the carboxyl groups. P(NIPAM‐co‐MAA‐co‐ODA) was more surface‐active than P(NIPAM‐co‐MAA) in the full range pH, pH 2.0–8.5, due to the hydrophobic effect of ODA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Generalized Nonaqueous Sol–Gel Synthesis of Different Transition‐Metal Niobate Nanocrystals and Analysis of the Growth Mechanism
Authors: Zhang Lizhi , Garnweitner Georg , Djerdj Igor , Antonietti Markus , Niederberger Markus 
Published: March 2008

AbstractA general nonaqueous route for the synthesis of phase‐pure transition‐metal niobate (InNbO4, MnNb2O6, and YNbO4) nanocrystals was developed based on the one‐pot solvothermal reaction of niobium chloride and the corresponding transition‐metal acetylacetonates in benzyl alcohol at 200 °C. All samples were carefully characterized by XRD, TEM, HRTEM, and energy‐dispersive X‐ray (EDX) analysis. The crystallization mechanism of these niobate nanocrystals points to a two‐step pathway. First, metal hydroxide crystals and amorphous niobium oxide are formed. Second, metal niobate nanocrystals are generated from the intermediates by a dissolution–recrystallization mechanism. The reaction mechanisms, that is, the processes responsible for the oxygen supply for oxide formation, were found to be rather complex and involve niobium‐mediated ether elimination as the main pathway, accompanied by solvolysis of the acetylacetonate ligands and benzylation reactions.
Eine Enzyklopädie für das Kaiserreich
Authors: Stöltzner Michael 
Published: March 2008

AbstractAn Encyclopedia for the Empire.In the preface to the universal encyclopediaDie Kultur der Gegenwart(The Culture of the Present), the editor‐in‐chief Paul Hinneberg places his project – not openly but nevertheless unequivocally – in the tradition of the FrenchEncyclopédiethat Diderot and d'Alembert had organized from 1751 until 1765. The attempt to accomplish anew such a large‐scale project and, in this way, to win the German Empire the kind of intellectual leadership which theEncyclopédie,in historical retrospect, had achieved for the epoch of Enlightenment, required to convince the leading scholars, scientists, and technicians of the nation to participate in the endeavor and to assemble their contributions under a common systematic agenda through which this universal encyclopedia would distinguish itself from all dictionaries and disciplinary encyclopedias. While theEncyclopédiefollowed to a large extent an empiricist philosophy, Hinneberg trusted in the integrative function of the concept of culture and the ability of his contributors to elucidate the history of their respective disciplines and to connect them with neighboring fields of culture. The present contributions argues that although, from a philosophical point of view, the historicist tack taken by Hinneberg makes the concept of culture quite blurry, it nevertheless provides enough cohesive structure such that the work, even though unfinished as a consequence of war and inflation, represents a faithful picture of its epoch that Hinneberg understands as an epoch of transition.
Delivery of peptides to the brain: Emphasis on therapeutic development
Authors: Banks William A. 
Published: March 2008

AbstractPeptides and regulatory proteins hold great promise as therapeutic agents for the central nervous system (CNS). However, the blood–brain barrier (BBB) is a major obstacle to the delivery of these potential therapeutics to their site of action. We concentrate here on the vascular BBB, which is comprised of the capillary bed of the brain specially modified to prevent the production of a plasma ultrafiltrate. For many peptides and proteins, this physical barrier is reinforced by enzymatic activities at the BBB, CNS, and peripheral tissues, short half‐lives and large volumes of distribution in the blood, binding proteins in blood, and brain‐to‐blood efflux systems. Nevertheless, there are pathways through which substances can cross. Small, lipid soluble substances cross by the nonsaturable mechanism of transmembrane diffusion, but even water‐soluble peptides can cross to some degree. Many endogenous peptides and regulatory proteins cross the BBB by way of selective, saturable transport systems. For enzymatically resistant substances with long circulating half‐lives and small volumes of distribution, such as antibodies, erythropoietin, and enzymes, substances can enter the CNS in therapeutic amounts through the residual leak of the BBB, termed the extracellular pathways. Recent examples show that the BBB transporters for peptides and regulatory substances are modifiable. This provides both a therapeutic opportunity and the potential for disease to arise from BBB dysfunctions. In the last case, the BBB itself is a therapeutic target. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 589–594, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com