bluuebunny/crossref_metadata_2025_split huggingface dataset:
6FDA‐TAPOB hyperbranched polyimide‐silica hybrids for gas separation membranes
Authors: Suzuki Tomoyuki , Yamada Yasuharu , Itahashi Kumi 
Published: April 2008

AbstractPhysical and gas transport properties of hyperbranched polyimide‐silica hybrid membranes were investigated. Hyperbranched polyamic acid as a precursor was prepared by polycondensation of a triamine, 1,3,5‐tris(4‐aminophenoxy) benzene (TAPOB), and a dianhydride, 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA), and subsequently modified a part of end groups by 3‐aminopropyltrimethoxysilane (APTrMOS). The hyperbranched polyimide‐silica hybrid membranes were prepared by sol–gel reaction using the polyamic acid, water, and alkoxysilanes. 5% weight‐loss temperature of the hybrid membranes increased with increasing silica content, indicating effective crosslinking at polymer‐silica interface mediated by APTrMOS moiety. On the other hand, glass transition temperature of the hybrid membranes prepared with methyltrimethoxysilane (MTMS) showed a minimum value at low silica content region, suggesting insufficient formation of three‐dimensional SiOSi network compared to the hybrid membranes prepared with tetramethoxysilane (TMOS). CO2, O2, N2, and CH4 permeability coefficients of the hybrid membranes increased with increasing silica content. Especially for TMOS/MTMS combined system, the hybrid membranes showed simultaneous enhancements of gas permeability and CO2/CH4 separation ability. It was concluded that the 6FDA‐TAPOB hyperbranched polyimide‐silica hybrid membranes have high thermal stability and excellent CO2/CH4 selectivity and are expected to apply to high‐performance gas separation membranes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Structure and properties of new reversibly crosslinked iPP/LDPE blends
Authors: Bouhelal S. , Cagiao M. E. , Khellaf S. , Benachour D. , Baltá Calleja F. J. 
Published: April 2008

AbstractReversibly crosslinked blends of isotactic polypropylene and low density polyethylene (iPP/LDPE) were prepared in the presence of crosslinking agents using reactive extrusion. The structure and properties of the modified blends were investigated by means of wide‐angle X‐ray scattering (WAXS), differential scanning calorimetry (DSC), and macro‐ and micro‐mechanical measurements. The crystallinity of the modified samples (LDPE, iPP, and their blends) does not seem to be so much affected by the crosslinking process. Results show that the microhardness of the iPP/LDPE blends notably increases with the iPP content. The micromechanical properties of the modified blends only improve slightly as a consequence of the crosslinking process. In the iPP samples, and also in the iPP/LDPE blends, this process gives rise to the appearance of new, crystalline ethylenic chains, as evidenced by the calorimetric measurements. Furthermore, the impact strength of the modified materials is improved as compared with that of the original ones, while some of the crosslinked blends show a ductile fracture behavior. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
DIN 1052:2004 – Neue Grundlagen für Entwurf, Berechnung und Bemessung von Holzbauwerken – Teil 3: Bemessung von einteiligen Holzbauteilen
Authors: Lißner Karin , Rug Wolfgang , Steinmetz Dieter 
Published: April 2008

AbstractEs werden die Nachweise für die Grenzzustände der Tragfähigkeit für einteilige Holzbauteile unter Zug‐, Druck‐ und Biegebeanspruchung beschrieben.
Structural propensities in the heme binding region of apocytochrome b5. II. Heme conjugates
Authors: Davis Ronald B. , Lecomte Juliette T. J. 
Published: April 2008

AbstractIn the absence of heme cofactor, the water‐soluble domain of rat microsomal cytochrome b5 (cyt b5) contains a long flexible region within its 42‐residue heme‐binding loop. Heme capture induces this region to fold into a well‐defined structure containing helices H3‐H5, each separated by a turn, with His39 and His63 serving as axial ligands to the heme iron. We have shown that the H4 region of the apoprotein has the greatest tendency for disorder within the isolated binding loop. Here, the effect of the His63‐iron bond and proximity of heme plane on the population of helical conformation in H4 and H5 was investigated by synthesis and characterization of a peptide‐sandwiched mesoheme construct in which two H4‐H5 peptides were covalently attached to a single cofactor. Spectroscopic data indicated that a holoprotein‐like bis‐histidine coordination state was achieved over a pH range from 7 to 9. Trifluoroethanol titrations of the construct and the analogous free peptide under these pH conditions revealed that heme proximity and iron ligation were insufficient to promote helix formation in H4 and H5. These observations were used to assess the role of disordered regions in heme capture and the loop‐scaffold interface in holoprotein folding and stability. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 556–566, 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
Oxidation of Aromatic Alcohols in Irradiated Aqueous Suspensions of Commercial and Home‐Prepared Rutile TiO2: A Selectivity Study
Authors: Augugliaro Vincenzo , Caronna Tullio , Loddo Vittorio , Marcì Giuseppe , Palmisano Giovanni , Palmisano Leonardo , Yurdakal Sedat 
Published: April 2008

AbstractThe photocatalytic oxidation of benzyl alcohol (BA) and 4‐methoxybenzyl alcohol (MBA) has been performed in pure water by using commercial TiO2 samples (Sigma‐Aldrich, Merck, Degussa P25) and rutile TiO2 prepared from TiCl4 at low temperature. Particular attention has been devoted to the identification of the produced aromatic compounds along with the formed CO2. Oxidation products such as the corresponding aromatic aldehyde and acid, as well as mono‐ and dihydroxylated aldehydes have been detected. The home‐prepared rutile sample showed a marked selectivity towards the formation of the aromatic aldehyde (38 and 60 % for BA and MBA, respectively), resulting in a three‐ to sevenfold improvement relative to commercial samples, with the only byproduct being CO2. This catalyst was found to be the most selective in the formation of aldehyde in water. By using the commercial or the calcined home‐prepared samples, many hydroxylated aromatic compounds were detected besides the aldehyde and the acid. This finding points to a higher selectivity performance of the home‐prepared rutile relative to the commercial TiO2 samples. Some of the home‐prepared samples were also dialysed to check the influence of the presence of Cl− species on catalyst reactivity and selectivity. We have attempted to explain the different reaction rate and selectivity observed for MBA and BA.
Grenzflächeneffekte bei Markenartikeln. Reinigungsmittel und Kosmetika
Authors: Nordskog Anette , von Rybinski Wolfgang 
Published: April 2008

AbstractDas komplexe Leistungsprofil chemischer Markenartikel für das Waschen und Reinigen sowie in der Kosmetik und ihre Zusammensetzung aus zahlreichen Wirkstoffen erfordern eine genaue Kenntnis der physikalisch‐chemischen Eigenschaften und der Wechselwirkung der Einzelkomponenten. Speziell physikalisch‐chemische Grenzflächeneffekte beeinflussen die Wirkung dieser Produkte. An grundlegenden Ergebnissen zum Ablaufverhalten wässriger Tensidlösungen von harten Oberflächen, der Bildung von Tensidschäumen und der Herstellung von stabilen dünnflüssigen Emulsionen wird aufgezeigt, welche Bedeutung die Grenzflächenforschung für Produkte für den Endverbraucher hat und welche Fortschritte erzielt werden konnten.
Modellmembranen auf Oberflächen. Verankert und doch mobil
Authors: Steinem Claudia , Janshoff Andreas 
Published: April 2008

AbstractMembranmodelle, die auf Festkörperoberflächen verankert sind, ermöglichen es, elektrische Verfahren sowie oberflächenanalytische und abbildende Methoden einzusetzen. So kann mit Membranen auf Oberflächen die laterale Organisation von Lipiden und Proteinen bis in den Nanometerbereich hinein visualisiert werden. Gleichzeitig sind diese Membranen sehr stabil und damit attraktiv für verschiedene Bereiche der Biosensorik. Durch eine individuelle Adressierung kleinster mikrometergroßer Membranareale mit verschiedenen Lipidkompositionen ist es möglich geworden, die Bindung von Proteinen an funktionale Membranen auf kleinstem Raum zu quantifizieren und zu parallelisieren. Für die Untersuchung von Transmembranproteinen haben sich neben den klassischen freitragenden und festkörperunterstützten Lipidmembranen in den letzten Jahren neue Systeme entwickelt, die als Hybrid dieser beiden Membrantypen angesehen werden können. Diese Entwicklungen sind gerade für die Wirkstoffforschung von Interesse, da die Mehrzahl aller Zielstrukturen von Wirkstoffen Transmembranproteine sind.
Alltägliche Phänomene. Grenzflächenchemische Spezialitäten
Authors: Venzmer Joachim 
Published: April 2008

AbstractIn vielen Bereichen des täglichen Lebens begegnen wir Grenzflächen, an denen sowohl kationische Tenside als auch Silikontenside eine wichtige Rolle spielen, aber dies passiert wahrscheinlich für die meisten Verbraucher mehr oder weniger unbewusst. Zum einen wird in diesem Artikel darauf eingegangen, wie die Trocknungshilfe in der Autowaschanlage wirkt und welche Vorgänge hinter Haarkonditionieren und Wäscheweichspülen stehen. Zum anderen wird gezeigt, welche im Grunde genommen widersprüchlichen Funktionen durch Silikontenside erfüllt werden können, von der Schaumstabilisierung in Polyurethanschäumen bis zum Entschäumen von Ölen.
Maßgeschneiderte Organische Oberflächen. Dünnstschichten
Authors: Kind Martin , Wöll Christof 
Published: April 2008

AbstractPhysik und Chemie an organischen Oberflächen stellen ein hochinteressanes Forschungsgebiet dar. Modellsysteme, die durch die Selbstassemblierung von Organothiolen hergestellt werden, bieten optimale Voraussetzungen für eine systematische Erkundung der grundlegenden Eigenschaften derartiger “weicher” Oberflächen. Dieser Artikel gibt einen Überblick über die Charakterisierung von SAMs (selbst‐assemblierten Monolagen) mit einer Vielzahl von oberflächenanalytischen Methoden und vermittelt grundlegende Einblicke in die hohe strukturelle Qualität und die enorme Vielseitigkeit der damit hergestellten organischen Oberflächen – bei einer gleichzeitig bestechenden Einfachheit der Herstellung. Der Artikel beschreibt auch einige grundlegende Anwendungsbeispiele wie die Deponierung von Metallen, die Herstellung biokompatibler Oberflächen und die Verankerung von Proteinen oder hochporösen molekularen Gitterstrukturen.
Römische Kalkbrennerei in Iversheim/Eifel
Authors: Schwedt Georg 
Published: April 2008

AbstractIn einer ausgegrabenen römischen Kalkbrennerei am Rande der Eifel – in Iversheim bei Bad Münstereifel, direkt an der Bahnlinie und B 51 – kann sich der Besucher über die Technik vor fast 2000 Jahren informieren. Die Kalkbrennerei wurde beim Verlegen einer Wasserleitung entdeckt und 1966 bis 1968 ausgegraben.
Von Mücken lernen
Authors: Harrer Roswitha 
Published: April 2008

AbstractBesucher von zoologischen Gärten kennen die kleine Windmaschine am Eingang der Tropenhäuser, die die beschlagene Brille wieder von den kondensierten Wassertröpfchen befreien soll. Gegen das lästige Beschlagen könnte möglicherweise auch eine besondere Oberflächenbeschichtung helfen, die das Anheften der winzigen Wassertröpfchen gar nicht erst zulässt.
DNA‐Kräne und ‐Baumaterial
Authors: Groß Michael 
Published: April 2008

AbstractDie Natur benutzt die wohldefinierte Doppelhelixstruktur zur effizienten und erstaunlich fehlersicheren Informationsverarbeitung. Im Labor kann man dieses Prinzip allerdings auch auf den Kopf stellen und die Sequenzinformation der DNA so manipulieren, dass gewünschte Struktur‐elemente und sogar mechanisch steuerbare Maschinenteile entstehen.
RNA‐Chaperone mit Breitbandwirkung
Authors: Hille‐Rehfeld Annette 
Published: April 2008

AbstractRNA‐Chaperone sind beim Entfalten der räumlichen Strukturen von Ribonucleinsäuren nicht wählerisch und können selbst die stabile native Konformation auflösen. Wie durch ihre Aktivität dennoch die funktionell bedeutsame native RNA‐Struktur begünstigt wird, zeigt die Untersuchung eines Ribozyms aus dem Schlauchpilz Neurospora crassa.
A variable field strength system for hyperpolarized noble gas MR imaging of rodent lungs
Authors: Dominguez‐Viqueira William , Parra‐Robles Juan , Fox Matthew , Handler William B. , Chronik Blaine A. , Santyr Giles E. 
Published: April 2008

AbstractHyperpolarized Noble Gas (HNG), 3He (helium) or 129Xe (xenon), MR imaging has become a promising approach for visualizing lung anatomy and function. It has been theoretically predicted that low field strengths (0.05–0.2 T) may provide optimal signal‐to‐noise ratio (SNR) and spatial resolution for clinical HNG MR imaging. These optimum field strengths correspond to frequencies between 1.62–6.5 MHz and 0.59–2.35 MHz for 3He and 129Xe respectively. The optimum field strength depends on the size and geometry of the sample and radiofrequency (RF) coil as well as the field dependence of the HNG MR properties in the lung (e.g., relaxation times, susceptibility effects). In particular, little is known about the field dependence of the apparent transverse relaxation time, T, which is expected to strongly influence HNG signal. In this paper, a broadband (0.1–100 MHz) variable field strength MR imaging system for rodents is described. A custom‐built resistive magnet was constructed and shimmed to provide the necessary homogeneity for imaging. RF coils and transmit/receive switches for different frequencies were also developed. Preliminary proton (1H) and hyperpolarized 129Xe images of test objects are presented, including a desiccated lung phantom. In vivo 129Xe signals from rat lungs were acquired at 73.5 mT and T was estimated to be approximately 80 ± 8 ms, in good agreement with previously reported values. The MR system developed should be useful for imaging rodent lungs at different field strengths to verify the expected SNR and spatial resolution possible using HNG imaging and to investigate long range diffusion and oxygen‐induced transverse relaxation. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 33B: 124–137, 2008
B1 inhomogeneity effect reduction for 2D spatial selective RF pulse using simulated annealing
Authors: Pang Yong , Shen Gary X. 
Published: April 2008

AbstractWith the development of the high‐field MRI system, the RF field inhomogeneity becomes a challenging problem in high flip angle excitation. In this study, a new RF pulse design method is proposed, which combines the simulated annealing (SA) algorithm and the k‐space method to attain a pulse which can compensate the RF field inhomogeneity effect. The RF pulse envelope is firstly initiated using the k‐space method and a cost function which contains the passband error and stopband error is defined. Then the SA is applied to refine the RF pulse shape to achieve low‐cost value. Finally, under inhomogeneous RF field an optimized RF pulse with improved flip angle accuracy can be obtained. Simulation results show that when compared with the pulse designed only using the k‐space method, the passband error can be decreased by 28%, 40%, and 75% for 90° excitation pulse, refocusing pulse, and 180° inversion pulse, respectively. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 33B: 75–83, 2008
Mechanism‐Guided Improvements to the Single Molecule Oxidation of Carbon Nanotube Sidewalls
Authors: Coroneus John G. , Goldsmith Brett R. , Lamboy Jorge A. , Kane Alexander A. , Collins Philip G. , Weiss Gregory A. 
Published: April 2008

AbstractReal‐time monitoring of carbon nanotube conductance during electrochemical and chemical etching reveals the electronic signatures of individual bond alteration events on the nanotube sidewall. Tracking the conductance of multiple single‐molecule experiments through different synthetic protocols supports putative mechanisms for sidewall derivatization. Insights gained from these mechanistic observations imply the formation of sidewall carboxylates, which are useful as handles for bioconjugation. We describe an electronic state required for efficacious chemical treatment. Such real‐time monitoring can improve carboxylate yields to 45 % or more. The experiments illustrate the power of molecular nanocircuits to uncover and direct the mechanisms of chemical reactions.
Dynamics of the Size Distribution of CdTe Quantum Dot Ensembles during Growth in Liquid and Crystalline Phases
Authors: Piepenbrock Marc‐Oliver M. , Stirner Tom , O'Neill Mary , Kelly Stephen M. 
Published: April 2008

AbstractWe recently reported that the growth rate of colloidal CdTe nanoparticles decreases by orders of magnitude when the particles undergo a phase transition from liquid to crystal. The dynamics of nanoparticle growth are dominated by this factor rather than the size dependence of the chemical potential. Herein we discuss how the phase transition affects the size distribution and photoluminescence quantum efficiency of the nanoparticles. We suggest that the absorption linewidth is a better monitor of size distribution than the photoluminescence linewidth because the photoluminescence quantum efficiency, which affects the latter via energy transfer, varies substantially with reaction time. We find that the size distribution broadens in the early stages of growth possibly because of inhomogeneities in the phase transition radius or because particles nucleated at later times coalesce with nanocrystals. The quantum efficiency is enhanced when tellurium is depleted in the reaction solution, giving a cadmium‐enriched surface. Batches with high initial tellurium and cadmium concentrations show a substantial amount of delayed nucleation, lower quantum efficiency and some anisotropic growth.
Skills needed to help communities manage natural resource conflicts
Authors: Singletary Loretta , Smutko L. Steven , Hill George C. , Smith Marilyn , Daniels Steven E. , Ayres Janet S. , Haaland Kay 
Published: April 2008

AbstractCompetition for natural resources has spawned unprecedented conflict between users, resulting in litigious and legislative actions. Citizens often expect Cooperative Extension professionals to engage communities in collaborative processes to manage these conflicts. This paper examines thirty‐five skills Cooperative Extension professionals need if they are to engage communities in collaborative processes. Survey methodology is used to assess the skills extension professionals perceive as most needed, and the ranked means of the perceived skill needs are presented. The results offer information useful to strengthen the capacity of extension professionals to play an important role in helping citizens manage natural resource conflicts.
Communication strategies in early adolescent conflict: An attributional approach
Authors: Scott Whitney 
Published: April 2008

AbstractThis study used attribution theory to investigate how attributions of responsibility influence early adolescents' communication strategy preference during friendship conflicts. It was hypothesized that selfresponsibility would be related to more cooperative ways of communicating (integrative strategies), whereas perceptions of other‐responsibility would be related to less cooperative ways of communicating (distributive or passive strategies). Participants ( N = 67) between the ages of twelve and fourteen read hypothetical conflict scenarios and described how they would communicate to resolve the conflict. Partial support for the hypothesis was found; however, complex details, such as the conflict theme and use of multicommunication strategies, were important variables in the resolution process. Conflict resolution programs, mediators, and clinicians might consider these complex aspects in trainings and practice.
CD137 ligand reverse signaling has multiple functions in human dendritic cells during an adaptive immune response
Authors: Lippert Undine , Zachmann Karolin , Ferrari David M. , Schwarz Herbert , Brunner Edgar , Latif A. H. M. Mahbub‐ul , Neumann Christine , Soruri Afsaneh 
Published: April 2008

AbstractT cell activation via dendritic cells (DC) is an important step in the adaptive immune response, which requires DC maturation, migration to lymph nodes and presentation of antigen to T cells. CD137 receptor expressed on activated T cells is a potent costimulatory molecule. Here, we investigated the functions of CD137 ligand (CD137L) in human monocyte‐derived DC during an immune response. Cross‐linking of CD137L on DC leads to cell maturation in an autocrine fashion, mostly via release of TNF‐α. Reverse signaling of CD137L also mediates migration of DC via up‐regulation of the CCR7 chemokine receptor, demonstrated by an in vivo MIP‐3β‐dependent SCID mouse migration model. Finally, CD137L‐activated DC induce differentiation of human T cells into potent Th1 effectors. Cocultivation of autologous T cells and CD137L‐activated DC in an antigen‐specific reaction leads to T cell proliferation and the release of IL‐12p70 and IFN‐γ. These findings deliver new insights into the multiple effects of reverse signaling of CD137L in human DC during the initiation of an adaptive immune response, including the key features of DC maturation, migration and, ultimately, antigen‐specific T cell differentiation.
Clinical application of regulatory T cells for treatment of type 1 diabetes and transplantation
Authors: Brusko Todd , Bluestone Jeffrey 
Published: April 2008

AbstractImmune regulation is a complex process that depends on the maintenance of self tolerance while retaining robust immune responses against microbes. The emergence of Treg as a central mechanism for immune regulation has generated a new paradigm where Treg‐resistant memory T cells and/or “defective” Treg lead to a breakdown in tolerance resulting in immune pathology. In this perspective, we highlight the opportunities and challenges in the field of Treg therapy.See accompanying commentary: http://dx.doi.org/10.1002/eji.200738107
Critical role of IL‐2 and TGF‐β in generation, function and stabilization of Foxp3+CD4+ Treg
Authors: Horwitz David A. , Zheng Song Guo , Wang Juhua , Gray J. Dixon 
Published: April 2008

AbstractCD4+Foxp3+ Treg consist of two indistinguishable subsets induced in either the thymus or the periphery. In addition to their suppressive activities, IL‐6 can convert natural Treg to pro‐inflammatory IL‐17‐producing cells, but those induced with IL‐2 and TGF‐β remain Treg. Unlike mouse CD4+CD25– cells, which rapidly become polyclonal Foxp3+CD25+ Treg when activated appropriately with IL‐2 and TGF‐β, human T cells require multiple stimulations to become similar suppressor cells.See accompanying commentary: http://dx.doi.org/10.1002/eji.200738111
How many mechanisms do regulatory T cells need?
Authors: Vignali Dario 
Published: April 2008

AbstractA plethora of new regulatory T cell (Treg) mechanisms have recently emerged. This raises two important questions. First, how many molecules or mechanisms are required for Treg to work? Second, how should we evaluate the contribution of any given Treg molecule/mechanism and how is this likely to relate (or not) to the phenotype seen in Scurfy/Foxp3‐deficient mice? In this discussion piece, I will briefly outline our current understanding of the Treg arsenal and address these important questions.See accompanying commentary: http://dx.doi.org/10.1002/eji.200838143