bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highlighting the role of the hydroxyl position on the alkyl spacer of hydroxypropyl‐β‐cyclodextrin for enantioseparation in capillary electrophoresis
Authors: Jiang Zhengjin , Thorogate Richard , Smith Norman William 
Published: December 2007

AbstractThis work investigates the resolving power of 2,3‐dihydroxypropyl‐β‐CD (2,3‐DHP‐β‐CD) and 3‐hydroxypropyl‐β‐CD (3‐HP‐β‐CD) as chiral mobile phase additives (CMPAs) using CE. The effects of experimental parameters (CD concentration, buffer pH, and buffer concentration) on enantiorecognition were investigated. More than 20 basic chiral drugs were resolved with satisfactory enantioselectivity. Comparison with 2‐hydroxypropyl‐β‐CD (2‐HP‐β‐CD) showed that one or both of the two new chiral selectors show enhanced enantiorecognition for several molecules with bulky substitutes, such as Zopiclone and Mianserin, however, 2‐HP‐β‐CD has higher enantiorecognition for most of the analytes. Further studies on the structures of analytes and CMPAs showed that the OH moiety on the propyl spacer plays an important role in the separation of some chiral drugs.
A new approach for the simulation of skeletal muscles using the tool of statistical mechanics
Authors: Böl M. , Reese S. 
Published: December 2007

AbstractThe structure of a skeletal muscle is dominated by its hierarchical architecture in which thousands of muscle fibres are arranged within a connective tissue network. The single muscle fibres consist of many force‐producing cells, known as sarcomeres. These micro biological engines are part of a motor unit and contribute to the contraction of the whole muscle. There are a lot of questions concerning the optimisation of muscle strength and agility. Standard experimental investigations are not sufficient to answer these questions because they do not supply enough information. Additionally, these methods are limited because not enough material for testing is accessible. To overcome these problems, numerical testing tools can be an adequate alternative. From the mechanical point of view the material behaviour of muscles is highly non‐linear. They undergo large deformations in space, thereby changing their shape significantly, so that geometrical nonlinearity has to be considered. Many authors use continuum‐based approaches in combination with the finite element method to describe such material behaviour. However, models of this kind require realistic constitutive relations between stress and strain which are difficult to determine in an inhomogeneous material. Furthermore, biomechanical information cannot be fully exploited in these models. The present approach is crucially based on the use of the finite element method. The material behaviour of the muscle is split into a so‐called active and a passive part. To describe the passive part special unit cells consisting of one tetrahedral element and six truss elements have been derived. Embedded into these unit cells are further truss elements which represent bundles of muscle fibres. Depending on the discretisation it is possible to simulate the material behaviour of e.g. artery walls characterised by oriented fibres or soft tissue including only non‐oriented fibres. In summary, the present concept has the advantage that a three‐dimensional model is developed which allows us take into account many physiological processes at the micro level.
Nanocrystalline apatites in biological systems: characterisation, structure and properties
Authors: Rey C. , Combes C. , Drouet C. , Lebugle A. , Sfihi H. , Barroug A. 
Published: December 2007

AbstractNanocrystalline apatitic calcium phosphates play a crucial role in calcified tissues and biomaterials. One of the most interesting characteristics of biomimetic apatite nanocrystals is the existence of a surface hydrated layer essentially related to their formation process in solution. This hydrated layer shows specific spectroscopic characteristics. It seems to exist in its nascent state only in wet samples and is altered on drying. This surface‐hydrated layer progressively disappears as the stable apatite domains develop. The surface ions can be rapidly and reversibly exchanged in solution, mainly with selected bivalent species. The exchange reactions clearly reveal the existence of two domains: the relatively inert apatite core and the very reactive surface‐hydrated domains. The structure of the hydrated layer has been shown to be reversibly affected by the constituting ions. Such a surface layer in bone apatite nanocrystals could participate actively in homeostasis and probably other regulation processes. The specificity of biomimetic apatite nanocrystals also opens interesting possibilities in materials science. The mobility of the mineral ions on the crystal surface, for example, allows strong bonding and interactions either with other crystals or with different substrates. Inter‐crystalline interactions have been described as a “crystal fusion” process in vivo and they could be involved in the setting reaction of biomimetic calcium phosphate cements. Ceramic‐like materials using the surface interaction capabilities of the nanocrystals can be produced at very low temperature (below 200 °C). The surface‐hydrated layer could also be involved in interactions with macromolecules and polymeric materials or in the coating of implants. The ion exchange and adsorption capabilities of the nanocrystals could probably be used for drug release, offering a range of possible behaviours.
Chemistry, ultrastructure and porosity of monophasic and biphasic bone forming materials derived from marine algae
Authors: Spassova E. , Gintenreiter S. , Halwax E. , Moser D. , Schopper C. , Ewers R. 
Published: December 2007

AbstractThe research on bioceramics during the last decades has proved that the bioactivity of inorganic bone grafts depends fundamentally on an optimal combination of chemistry and structural porosity. This study presents a comparison of a resorbable monophasic hydroxyapatite (HA) and several newly developed resorbable biphasic hydroxyapatite – ß‐tricalcium phosphate (HA/TCP) composites both derived from naturally grown red marine algae with respect to the phase composition, microstructure and porosity. The highly porous three dimensional mineral scaffold of the native alga is maintained in the final products all investigated materials and possesses a pronounced interconnecting microporous structure. There are generally high values of specific porosity calculated for all tested materials: 1.07 cm3/g for pure phycogenic HA and between 0.65 cm3/g and 1.04 cm3/g for phycogenic biphasic HA/TCP composites with various HA/TCP ratios. The ultrastructure of the phycogenic HA/TCP composites changes significantly with the building and the increase of the ß‐TCP phase due to the bigger polyedric ß‐TCP crystals compared to the finer polycrystalline HA. Despite these structural changes the interconnected porous scaffold is kept throughout the production process. In all investigated materials the porosity is mainly based on pores with pore sizes between 1 and 10 μm in diameter, which is given by the structure of the natural alga. The specific chemistry combined with the structural porosity is decisive for the high in‐vivo bioactivity of the studied materials.
Fixation of porous calcium phosphate with expanded bone marrow cells using an autologous plasma clot
Authors: Schildhauer T.A. , Seybold D. , Geßmann J. , Muhr G. , Köller M. 
Published: December 2007

AbstractMultipotent human mesenchymal stromal cells (hMSCs) are currently the most promising cell type for regenerative medicine and tissue engineering. For clinical applications with special focus on fracture repair a method to deliver in vitro‐expanded bone marrow cells to the fracture site is presented. Autologous blood plasma clotting was used to fix expanded cells and synthetic tricalcium phosphate particles. A jelly‐like but solid composite matrix was obtained which could easily be handled by the surgeon. The majority of embedded cells remained viable after the plasma gelation process, as was determined by fluorescence microscopy. Experimental cell culture over a period of 15 days showed proliferating mesenchymal stromal cells within the plasma clot.
Development of an universal affinity fusion tag (Poly‐DOPA) for immobilizing recombinant proteins on biomaterials
Authors: Jennissen H. P. , Laub M. 
Published: December 2007

AbstractThe covalent and non‐covalent immobilization of growth factors such as recombinant human bone morphogenetic protein 2 (rhBMP‐2) on metals and bone replacement materials in bioactive form is a recent development. Up to now the immobilization technology usually involved the chemical modification and activation of the biomaterial surface followed by attachment of the bioactive protein. Here we suggest an alternative method in which an affinity tag fused to an active protein will allow immobilization without additional chemistry. For biomaterials such as minerals, metals (titanium, steel, CoCrMo), glass ceramics, teflon and possibly bone and teeth ideal adhesion molecules would be the foot proteins (Mefps) of the mussel M. edulis which contain the rare amino acid dihydroxy phenylalanine (DOPA). Recently it could be shown by Messersmith's group that a single DOPA‐molecule can be non‐covalently bound to titanium dioxide surface with a dissociation energy of 22.2 kcal/mol (Lee, H.; Scherer, N. F.; Messersmith, P. B. Proc. Natl. Acad. Sci. U. S. A 2006, 103, 12999–13003).We therefore propose the DOPA‐tag as a general and versatile affinity tag for the immobilization of proteins on biomaterials.
Biomaterials 2006 — International Symposium — Essen, September 5–8, 2006
Authors: Jennisen H.P. 
Published: December 2007

AbstractIn the international symposium „Biomaterials 2006”︁ the German Society of Biomaterials (DGBM), the organizers of the XIXth „Aachen Colloquium on Biomaterials”︁ and the organizers of the 9th „International Essen Symposium on Biomaterials and Biomechanics: Fundamentals and Clinical Applications”︁ pooled forces thus bundling the potentials of the state of North Rhine‐Westphalia in the area of biomaterials to a nationwide and international initiative.Biomaterial development is the motor of progress in implantology. In the past decades, where bulk behaviour, biocompatibility, stability and texturing of biomaterials were key areas of research and progress, one may speak of the era of „dumb materials”︁. At the turn of the century the concept, that the future of implants lies in their surface, gained acceptance and with that the evolution of „smart biomaterials”︁ (Anderson et al. 2004) began. Biocoating and functionalization of surfaces were developed with the aim of the surface directing the specific behaviour of contacting tissue cells and/or attracting precursor cells by the release of chemotactic substances. Today new functionalities are emerging such as responsive or on‐demand surfaces, allowing an on‐and‐off switching. A new focus was put on areas which have been little noticed such as ischemia and reperfusion damage due to the implantation process. Similarly nano and micro particles either therapeutically applied as delivery devices or due to wear and causing adverse reactions were discussed.„Biomaterials 2006”︁ was an exceptional, very successful meeting with scientists from 18 countries and 140 submitted abstracts and presentations (see Jennissen, H.P. (2006) BIOmaterialien 7, 107–254) from nearly every facet of biomaterials. The present volume represents a selection of 14 key papers from the meeting which give a fine impression of the trends experienced at „Biomaterials 2006”︁ and the developments to come.
Fyn is a novel target of (−)‐epigallocatechin gallate in the inhibition of JB6 Cl41 cell transformation
Authors: He Zhiwei , Tang Faqing , Ermakova Svetlana , Li Ming , Zhao Qing , Cho Yong‐Yeon , Ma Wei‐Ya , Choi Hong‐Seok , Bode Ann M. , Yang Chung S. , Dong Zigang 
Published: December 2007

AbstractThe cancer preventive action of (−)‐epigallocatechin gallate (EGCG), found in green tea, is strongly supported by epidemiology and laboratory research data. However, the mechanism by which EGCG inhibits carcinogenesis and cell transformation is not clear. In this study, we report that EGCG suppressed epidermal growth factor (EGF)‐induced cell transformation in JB6 cells. We also found that EGCG inhibited EGF‐induced Fyn kinase activity and phosphorylation in vitro and in vivo. Fyn was implicated in the process because EGF‐induced JB6 cell transformation was inhibited by small interfering RNA (siRNA)‐Fyn‐JB6 cells. With an in vitro protein‐binding assay, we found that EGCG directly bound with the GST‐Fyn‐SH2 domain but not the GST‐Fyn‐SH3 domain. The Kd value for EGCG binding to the Fyn SH2 domain was 0.367 ± 0.122 µM and Bmax was 1.35 ± 0.128 nmol/mg. Compared with control JB6 Cl41 cells, EGF‐induced phosphorylation of p38 MAP kinase (p38 MAPK) (Thr180/Tyr182), ATF‐2 (Thr71) and signal transducer and activator of transcription 1 (STAT1) (Thr727) was decreased in siRNA‐Fyn‐JB6 cells. EGCG could inhibit the phosphorylation of p38 MAPK, ATF‐2, and STAT1. The DNA binding ability of AP‐1, STAT1, and ATF‐2 was also decreased in siRNA‐Fyn‐JB6 cells. Overall, these results demonstrated that EGCG interacted with Fyn and inhibited Fyn kinase activity and thereby regulated EGF‐induced cell transformation. Inhibition of Fyn kinase activity is a novel and important mechanism that may be involved in EGCG‐induced inhibition of cell transformation. © 2007 Wiley‐Liss, Inc.
Electrostatic interactions effect in the aminolysis of some β‐lactams in the presence of poly(ethyleneimine):structure‐reactivity
Authors: Arcelli Antonio , Porzi Gianni , Rinaldi Samuele , Sandri Monica 
Published: December 2007

AbstractThe aminolysis reaction of a series of β‐lactams in the presence of poly(ethyleneimine) (PEI) at 30°C and pH = 8.40 has been studied. The substrates investigated follow a pseudo first order rate, except two β‐lactams which show a two step consecutive reaction. Increasing the polyelectrolyte concentration, Michaelis–Menten type kinetics are been observed and for four substrates a more complex rate behaviour was verified owing to the polyelectrolyte inhibition effect. Both the binding constant K1 between polyelelectrolyte and β‐lactam and the first order rate constant of the reactive complex decomposition kcat were calculated. The substituent effect at C‐6′ or C‐7′ position of β‐lactam on the aminolysis rate does not correlate with the σI value (Taft plot). Most probably, steric and electronic effects are important, but the electrostatic ones are determining factors for the relevant acceleration attributable to both the binding phenomena and the increased reactivity of the substrate–polyelectrolyte complex. The comparison between poly(ethyleneimine) and Human Serum Albumin (HSA) is also discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Facile preparation of core‐crosslinked micelles from azide‐containing thermoresponsive double hydrophilic diblock copolymer via click chemistry
Authors: Jiang Xiaoze , Zhang Jingyan , Zhou Yueming , Xu Jian , Liu Shiyong 
Published: December 2007

AbstractDouble hydrophilic diblock copolymer, poly(N,N‐dimethylacrylamide)‐b‐poly(N‐isopropylacrylamide‐co‐3‐azidopropylacrylamide) (PDMA‐b‐P(NIPAM‐co‐AzPAM), containing azide moieties in one of the blocks was synthesized via consecutive reversible addition‐fragmentation chain transfer polymerization. The obtained diblock copolymer molecularly dissolves in aqueous solution at room temperature, and can further supramolecularly self‐assemble into core‐shell nanoparticles consisting of thermoresponsive P(NIPAM‐co‐AzPAM) cores and water‐soluble PDMA coronas above the lower critical solution temperature of P(NIPAM‐co‐AzPAM) block. As the micelle cores contain reactive azide residues, core crosslinking can be facilely achieved upon addition of difunctional propargyl ether via click chemistry. In an alternate approach in which the PDMA‐b‐P(NIPAM‐co‐AzPAM) diblock copolymer was dissolved in a common organic solvent (DMF), the core‐crosslinked (CCL) micelles can be fabricated via “click” crosslinking upon addition of propargyl ether and subsequent dialysis against water. CCL micelles prepared by the latter approach typically possess larger sizes and broader size distributions, compared with that obtained by the former one. In both cases, the obtained (CCL) micelles possess thermoresponsive cores, and the swelling/shrinking of which can be finely tuned with temperature, rendering them as excellent candidates as intelligent drug nanocarriers. Because of the high efficiency and quite mild conditions of click reactions, we expect that this strategy can be generalized for the structural fixation of other self‐assembled nanostructures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 860–871, 2008
Reaction parameters in the RAFT mediated dispersion polymerization of styrene
Authors: Saikia Prakash J. , Lee Jung Min , Lee Kangseok , Choe Soonja 
Published: December 2007

AbstractMonodisperse polystyrene (PS) particles were prepared by a living radical dispersion polymerization with a reversible addition‐fragmentation chain transfer (RAFT) agent in an ethanol medium. In the presence of RAFT agent, the effects of various reaction parameters on the characteristics of PS particles were systematically investigated. When no RAFT agent was involved, the number‐average molecular weight (Mn) of the PS particles increased from 17,800 to 30,000 g/mol, but the weight‐average diameter (Dw) decreased from 2.54 to 2.06 μm with the increase of poly(N‐vinylpyrrolidone) content from 4.0 to 16.0 wt %. No correlation between the Mn and the coefficient of variation (CV) was observed. However, when the RAFT concentration varied from 0 to 2.0 wt %, all of the conversion, Mn, Dw, CV, and polydispersity index (Mw/Mn) decreased. This indicates that the RAFT agent alters the inverse behavior between the molecular weight (MW) and particle size shown in the conventional dispersion polymerization. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 872–885, 2008
Using apparent molecular weight from SEC in controlled/living polymerization and kinetics of polymerization
Authors: Guillaneuf Yohann , Castignolles Patrice 
Published: December 2007

AbstractApparent molecular weights from size exclusion chromatography, that is molecular weights relative to standards of a nature different to that of the polymer sample being studied, are frequently used. We use calculations corresponding to realistic cases to provide guidelines for situations when, and to what extent, apparent molecular weights (MWs) can be meaningful. In controlled polymerization, we show how, without due care, use of apparent MW, could lead to the incorrect conclusion that the reaction was not controlled, whereas the true MWs would be close to theoretical values. We show here that the quality of the eluent as a solvent for the standard and the polymer sample is a good indication of the accuracy and the significance of the apparent polydispersity index. Accurate Mark–Houwink–Sakurada parameters are of limited availability, but the data about solvent quality available in handbooks or available from static light scattering measurements. Apparent Mn is of no use in controlled polymerization if simple simulations as performed in this work do not validate their use. The determination of transfer constants by the Mayo plot can be performed using apparent Mn without introducing any significant error, contrary to apparent weight‐average molecular weight Mw or apparent ln number distribution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 897–911, 2008
Study on the viscoelastic properties of the epoxy surface by means of nanodynamic mechanical analysis
Authors: Zhang Yang‐Fei , Bai Shu‐Lin , Yang Da‐Yong , Zhang Zhong , Kao‐Walter Sharon 
Published: December 2007

AbstractThe viscoelastic properties of the epoxy surface have been investigated by nanodynamic mechanical analysis (nano‐DMA). Both a Berkovich tip and a conospherical tip were used under the condition of different forces (i.e., different penetration depths) in the frequency range of 10–200 Hz. Loss tangent and storage modulus are characteristics that describe the viscoelastic properties. The effect of force frequency, penetration depth, and tip shape on the viscoelastic properties is studied and discussed according to the features of microstructures and mobility of molecular chains. The experimental results show important variations when the penetration depth is shallow (<30 nm). As the depth becomes deeper, the results tend to be stable and become almost constant over 120 nm. The two kinds of indenter tip can cause a slight difference of the storage modulus. A “master curve” of the storage modulus as a function of force frequency is established. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 281–288, 2008
A ubiquitous IAs access platform (UIAP) over UPnP
Authors: Huang Chung‐Ming , Lin Ming‐Sian , Wong Hon‐Long 
Published: December 2007

AbstractThe radical development in information technology makes the information appliances (IAs) able to interact and share information using the universal plug and play (UPnP) protocol. Inter‐IA interactions that involve more than one IA do exist in the future digital home network. Nowadays, inter‐IA interactions are developed by system and service providers and are fixed. It is difficult for users to customize their inter‐IA interactions. In this paper, we propose the service interaction script (SIS) language, which is a flow control language for users to customize their own inter‐IA interactions through the Web interfaces in the UPnP home network. Domain‐specific statements for the development of the inter‐IA interactions in SIS are (i) IA access statement, (ii) parallel statement and (iii) interaction event handling statement. On the other hand, the ubiquitous IAs access platform (UIAP) that allows users to use handheld devices to access the IA base on the UPnP protocol is also developed. UIAP provides the Web interfaces, i.e. (i) control panel and (ii) interaction customization panel, for users to access IAs remotely using handheld devices with or without the UPnP capability. The interaction customization panel contains (i) an easy mode and (ii) an advanced mode for users to customize inter‐IA interactions defined by themselves through the Web interfaces using SIS. In the easy mode, inter‐IA interaction customizations are achieved through the Web graphical user interface components and translated into SIS programs; in the advanced mode, users can write SIS programs directly. Copyright © 2007 John Wiley & Sons, Ltd.
Effectiveness of multiple pageable page sizes for commercial applications
Authors: Jann Joefon , Dubey Niteesh , Pattnaik Pratap , Burugula R. Sarma 
Published: December 2007

AbstractThis paper investigates the computational characteristics of the software applications that are developed to support typical modern e‐commerce applications. These applications have a significant impact on global commerce, and their influence is expected to continue. We show that the micro‐architectural features of the memory subsystem, assisted by the operating system (such as the use of concurrent pageable page sizes), can significantly improve the performance of these applications. In particular, we show that using 64 kB page size in addition to the default 4 kB page size provides substantial throughput improvements for a typical commercial application (Trade6) without adding any complexity for the application developer or the system administrator. Copyright © 2007 John Wiley & Sons, Ltd.