bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amyloids: Not Only Pathological Agents but Also Ordered Nanomaterials
Authors: Cherny Izhack , Gazit Ehud 
Published: April 2008

AbstractAmyloid fibers constitute one of the most abundant and important naturally occurring self‐associated assemblies. A variety of protein and peptide molecules with various amino acid sequences form these highly stable and well‐organized assemblies under diverse conditions. These assemblies display phase states ranging from liquid crystals to rigid nanotubes. The potential applications of these supramolecular assemblies exceed those of synthetic polymers since the building blocks may introduce biological function in addition to mechanical properties. Here we review the structural characteristics of amyloidal supramolecular assemblies, their potential use as either natural or de novo designed sequences, and the range of applications that have been demonstrated so far.
NMR studies of poly(2‐hydroxy ethyl methacrylate‐co‐2‐vinyl pyridine)
Authors: Hooda Sunita , Brar A. S. , Goyal Ashok Kumar 
Published: April 2008

AbstractCopolymers of 2‐hydroxy ethyl methacrylate‐2‐vinyl pyridine (H/V) of different composition were synthesized by free radical bulk polymerization using azobisisobutyronitrile (AIBN) as an initiator under nitrogen atmosphere. The copolymer compositions were calculated from 1H NMR spectra. The reactivity ratios for H/V copolymers obtained from a linear Kelen‐Tudos method (KT) and nonlinear error‐in‐variables method (EVM) are rH = 0.50 ± 0.10, rV = 1.04 ± 0.08 and rH = 0.55, rV = 1.06 respectively. The complete spectral assignment of methine, methylene, methyl, carbonyl, and aromatic carbon regions in term of compositional and configurational sequences of H/V copolymers were done with the help of 13C{1H} NMR, distortionless enhancement by polarization transfer (DEPT), two‐dimensional heteronuclear single quantum coherence (HSQC) along with total correlated spectroscopy (TOCSY). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Making polyvinyl alcohol films iodinated at solution state before casting and its application
Authors: Shin Eun Joo , Lyoo Won Seok , Lee Yang Hun 
Published: April 2008

AbstractThis research focused on the manufacture a polarizing film with PVA iodinated at solution before casting (IBC) film, which was prepared by casting aqueous solutions of 10 wt % poly(vinyl alcohol) (PVA) containing boric acid with 0, 0.1, 0.5, and 1.0 mol/L of I2/KI aqueous solution, and I2/KI(1:2) with 0, 5, and 10 wt % of PVA. The lights of wavelengths between 450 and 700 nm were polarized in UV analysis. The degree of polarization and transmittance of the IBC polarizing film (10 wt % I2/KI and 0.5 mol/L boric acid) are 99.9% and 43.2%, respectively. The resistance of the heat and humidity of IBC polarizing films was higher than that of commercial polarizing films, which were elucidated by changing the transmittance of the films. This can be explained by the fact that the interaction between polyiodine molecules and PVA chains as the state of IBC is higher than that of the commercial state. The effect of boric acid may be strengthened for the resistance of heat and humidity. Crosslinking by boric acid improved thermal properties of the IBC polarizing films, resulting from the increases of degradation temperature in DSC and TG analysis. And the unit cell broadening occurred, which was caused by the intrusion of boric acid into PVA chains in X‐ray analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Properties of polypropylene/layered‐silicate nanocomposites and melt‐spun fibers
Authors: Lee Seung Hwan , Youn Jae Ryoun 
Published: April 2008

AbstractPolypropylene (PP)/layered‐silicate organoclay nanocomposites and their fibers were prepared by melt compounding and melt spinning, respectively, in the presence or absence of compatibilizer (PP‐based maleic anhydride compatibilizer) to examine the effects of the organoclay dispersion and rheological behavior on the internal structure and tensile properties of the nanocomposite fibers. The compatibilized nanocomposites showed solidlike plateau behavior and strain hardening due to a three‐dimensional network structure in the shear and uniaxial elongational flows. The tensile properties of the nanocomposite fibers were reduced compared with those of the pure PP fibers because some of the layered silicates were present as partially aggregated forms and the molecular weight of the compatibilizer was lower than that of the pure PP matrix. It was also found that the tenacity of the nanocomposite fiber increased and then decreased as the compatibilizer content increased because the compatibilizer affected the internal structure of the nanocomposite fibers. The positive effect of the compatibilizer was to generate a more effective exfoliated structure of organoclay in the polymer matrix. The negative effect was that the melt‐spun nanocomposite fiber had a lower molecular weight than the pure PP fiber because the compatibilizer had a lower molecular weight. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Information ethics for and from Africa
Authors: Capurro Rafael 
Published: April 2008

AbstractThe first part of this article deals with some initiatives concerning the role of information ethics for Africa, such as the New Partnership for Africa's Development, United Nations Information Communications Technology (ICT), and the African Information Society Initiative particularly since the World Summit on the Information Society. Information Ethics from Africa is a young academic field, and not much has been published so far on the impact of ICT on African societies and cultures from a philosophical perspective. The second part of the article analyzes some recent research on this matter particularly with regard to the concept of ubuntu. Finally, the article addresses some issues of the African Conference on Information Ethics held February 3–5, 2007, in Pretoria, South Africa.1The following essay is adapted from a keynote address delivered at the Africa Information Ethics Conference in Pretoria, South Africa, February 5–7, 2007. Under the patronage of UNESCO, sponsored by the South African government, and organized with assistance from the Department of Information Science at the University of Pretoria, the School of Information Studies at the University of Wisconsin‐Milwaukee, and the supporters and members of the International Center for Information Ethics (ICIE), the theme of the conference was “Ethical Challenges in the Information Age: The Joy of Sharing Knowledge.” The full version of the address as well as selected articles from the conference were published in Vol. 7 of ICIE's online journal, International Review of Information Ethics (for more information, visit http://icie.zkm.de)
The justification of intellectual property: Contemporary philosophical disputes
Authors: Himma Kenneth Einar 
Published: April 2008

AbstractOnce taken for granted as morally legitimate, legal protection of intellectual property rights have come under fire in the last 30 years as new technologies have evolved and severed the link between expression of ideas and such traditional material‐based media as books and magazines. These advances in digital technology have called attention to unique features of intellectual content that problematize intellectual property protection; any piece of intellectual content, for example, can be simultaneously appropriated by everyone in the world without thereby diminishing the supply of that content available to others. This essay provides an overview and assessment of the arguments and counterarguments on the issue of whether intellectual property should be legally protected.
The value of probabilistic prediction
Authors: Buizza Roberto 
Published: April 2008

AbstractProbabilistic forecasts designed to estimate the probability density function of forecast states are potentially more valuable than single forecasts because (1) they can predict not only the most likely outcome but also the probability of occurrence of extreme and rare events and (2) probabilistic forecasts issued on consecutive days are usually more consistent than corresponding single forecasts. In this communication, the potential economic value of probabilistic and single forecasts are compared, and single and probabilistic forecasts of precipitation for a flooding event are analyzed to illustrate the potential value of consistency between successive forecasts. Copyright © 2008 Royal Meteorological Society
Night‐time NO3 and OH radical concentrations in the United Kingdom inferred from hydrocarbon measurements
Authors: Khan M. A. H. , Ashfold M. J. , Nickless G. , Martin D. , Watson L. A. , Hamer P. D. , Wayne R. P. , Canosa‐Mas C. E. , Shallcross D. E. 
Published: April 2008

AbstractThe hydrocarbon decay method (Rivett et al., 2003) has been used to analyse hydrocarbon data from four contrasting sites in the United Kingdom to estimate night‐time levels of NO3 and OH. Remarkably consistent results emerge using alkenes, revealing NO3 and OH levels in the range of 0.01–10 ppt and 1 × 104 − 1 × 106 molecule cm−3, respectively. Weak seasonal cycles are observed where NO3 levels peak in spring and OH in summer. Analysis using alkanes suggests that Cl atom levels of around 2 × 104 molecule cm−3 may be present. How Cl may be formed at night in such high quantities is unknown and may not be the answer to the disparity between the two methods. Copyright © 2008 Royal Meteorological Society
Schimmelpilzbildung im Bereich der Untersicht hölzerner Dachüberstände – Ursachen und Vermeidung
Authors: Göbelsmann Marc 
Published: April 2008

AbstractAn Außenflächen aus Holz oder Holzwerkstoffen sind insbesondere im Bereich der Untersicht von Dachüberständen vermehrt Schimmelpilzbildungen aufgetreten. Zur Vertiefung des Verständnisses der Ursachen dieses Problems wurden instationäre Berechnungen unter Berücksichtigung realitätsnaher klimatischer Randbedingungen vorgenommen.Die Berechnungen ergaben insbesondere für klare Nächte infolge der Wärmeabgabe durch Strahlung eine Abkühlung der Konstruktion auf deutlich unter der Lufttemperatur liegende Temperaturwerte. Dies führt zu einem dem Dampfdruckgefälle folgenden Feuchtetransport in das Bauteil mit dem Resultat einer zeitweise auftretenden Zunahme der Holzfeuchte in der untersten Schicht der Holzschalung. Die Ergebnisse weisen darauf hin, dass bereits vor dem Erreichen der Taupunkttemperatur bzw. vor der Bildung von Oberflächentauwasser eine beträchtliche Zunahme der Holzfeuchte erfolgt! Mit der Zunahme der Holzfeuchte geht eine Zunahme des Risikos der Schimmelpilzbildung einher.Es handelt sich bei der Schimmelpilzbildung im Bereich der Untersicht hölzerner Dachüberstände im Wesentlichen um ein bauphysikalisches Problem. Maßnahmen des Holzschutzes bekämpfen insofern lediglich die Symptome, jedoch nicht die Ursache der Schimmelpilzbildung! Eine Beseitigung der Ursache der Schimmelpilzbildung ist möglich, indem zwischen Dachschalung und Dachabdichtung eine dünne Wärmedämmung angeordnet wird. Maßnahmen des Holzschutzes sowie die Wahl geeigneter Hölzer bzw. Holzwerkstoffe werden flankierend als erforderlich angesehen.
Multiscale modeling of nucleic acids: Insights into DNA flexibility
Authors: Bomble Yannick J. , Case David A. 
Published: April 2008

AbstractThe elastic rod theory is used together with all‐atom normal mode analysis in implicit solvent to characterize the mechanical flexibility of duplex DNA. The bending, twisting, stretching rigidities extracted from all‐atom simulations (on linear duplexes from 60 to 150 base pairs in length and from 94‐bp minicircles) are in reasonable agreement with experimental results. We focus on salt concentration and sequence effects on the overall flexibility. Bending persistence lengths are about 20% higher than most experimental estimates, but the transition from low‐salt to high‐salt behavior is reproduced well, as is the dependence of the stretching modulus on salt (which is opposite to that of bending). CTG and CGG trinucleotide repeats, responsible for several degenerative disorders, are found to be more flexible than random DNA, in agreement with several recent studies, whereas poly(dA).poly(dT) is the stiffest sequence we have encountered. The results suggest that current all‐atom potentials, which were parameterized on small molecules and short oligonucleotides, also provide a useful description of duplex DNA at much longer length scales. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 722–731, 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
Conformational transitions of flanking purines in HIV‐1 RNA dimerization initiation site kissing complexes studied by CHARMM explicit solvent molecular dynamics
Authors: Sarzyńska Joanna , Réblová Kamila , Šponer Jiří , Kuliński Tadeusz 
Published: April 2008

AbstractDimerization of HIV‐1 genomic RNA is initiated by kissing loop interactions at the Dimerization Initiation Site (DIS). Dynamics of purines that flank the 5′ ends of the loop–loop helix in HIV‐1 DIS kissing complex were explored using explicit solvent molecular dynamics (MD) simulations with the CHARMM force field. Multiple MD simulations (200 ns in total) of X‐ray structures for HIV‐1 DIS Subtypes A, B, and F revealed conformational variability of flanking purines. In particular, the flanking purines, which in the starting X‐ray structures are bulged‐out and stack in pairs, formed a consecutive stack of four bulged‐out adenines at the beginning of several simulations. This conformation is seen in the crystal structure of DIS Subtype F with no interference from crystal packing, and was frequently reported in our preceding MD studies performed with the AMBER force field. However, as CHARMM simulations progressed, the four continuously stacked adenines showed conformational transitions from the bulged‐out into the bulged‐in geometries. Although such an arrangement has not been seen in any X‐ray structure, it has been suggested by a recent NMR investigation. In CHARMM simulations, in the longer time scale, the flanking purines display the tendency to move to bulged‐in conformations. This is in contrast with the AMBER simulations, which indicate a modest prevalence for bulged‐out flanking base positions in line with the X‐ray data. The simulations also suggest that the intermolecular stacking between purines from the opposite hairpins can additionally stabilize the kissing complex. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 732–746, 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
Improvements of enzyme activity and enantioselectivity via combined substrate engineering and covalent immobilization
Authors: Wang Pei‐Yun , Tsai Shau‐Wei , Chen Teh‐Liang 
Published: April 2008

AbstractEsterases, lipases, and serine proteases have been applied as versatile biocatalysts for preparing a variety of chiral compounds in industry via the kinetic resolution of their racemates. In order to meet this requirement, three approaches of enzyme engineering, medium engineering, and substrate engineering are exploited to improve the enzyme activity and enantioselectivity. With the hydrolysis of (R,S)‐mandelates in biphasic media consisting of isooctane and pH 6 buffer at 55°C as the model system, the strategy of combined substrate engineering and covalent immobilization leads to an increase of enzyme activity and enantioselectivity from VS/(Et) = 1.62 mmol/h g and VS/VR = 43.6 of (R,S)‐ethyl mandelate (1) for a Klebsiella oxytoca esterase (named as SNSM‐87 from the producer) to 16.7 mmol/h g and 867 of (R,S)‐2‐methoxyethyl mandelate (4) for the enzyme immobilized on Eupergit C 250L. The analysis is then extended to other (R,S)‐2‐hydroxycarboxylic acid esters, giving improvements of the enzyme performance from VS/(Et) = 1.56 mmol/h g and VS/VR = 41.9 of (R,S)‐ethyl 3‐chloromandelate (9) for the free esterase to 39.4 mmol/h g and 401 of (R,S)‐2‐methoxyethyl 3‐chloromandelate (16) for the immobilized enzyme, VS/(Et) = 5.46 mmol/h g and VS/VR = 8.27 of (R,S)‐ethyl 4‐chloromandelate (10) for free SNSM‐87 to 33.5 mmol/h g and 123 of (R,S)‐methyl 4‐chloromandelate (14) for the immobilized enzyme, as well as VS/(Et) = 3.0 mmol/h g and VS/VR = 7.94 of (R,S)‐ethyl 3‐phenyllactate (11) for the free esterase to 40.7 mmol/h g and 158 of (R,S)‐2‐methoxyethyl 3‐phenyllactate (18) for the immobilized enzyme. The great enantioselectivty enhancement is rationalized from the alteration of ionization constants of imidazolium moiety of catalytic histidine for both enantiomers and conformation distortion of active site after the covalent immobilization, as well as the selection of leaving alcohol moiety via substrate engineering approach. Biotechnol. Bioeng. 2008;101: 460–469. © 2008 Wiley Periodicals, Inc.
Control of protein adsorption on functionalized electrospun fibers
Authors: Grafahrend Dirk , Calvet Julia Lleixa , Klinkhammer Kristina , Salber Jochen , Dalton Paul D. , Möller Martin , Klee Doris 
Published: April 2008

AbstractElectrospun fibers that are protein resistant and functionalized with bioactive signals were produced by solution electrospinning amphiphilic block copolymers. Poly (ethylene glycol)‐block‐poly(D,L‐lactide) (PEG‐b‐PDLLA) was synthesized in two steps, with a PEG segment of 10 kDa, while the PDLLA block ranged from 20 to 60 kDa. Depending on the PEG and PDLLA segment ratio, as well as solvent selection, the hydrophilicity and protein adsorption could be altered on the electrospun mesh. Furthermore, an α‐acetal PEG‐b‐PDLLA was synthesized that allowed the conjugation of active molecules, resulting in surface functionalization of the electrospun fiber. Electrospun material with varying morphologies and diameter were electrospun from 10, 20, and 30 wt.% solutions. Sessile drop measurements showed a reduction in the contact angle from 120° for pure poly(D,L‐lactide) with increasing PEG/PDLLA ratio. All electrospun block PEG‐b‐PDLLA fibers had hydrophilic properties, with contact angles below 45°. The fibers were collected onto six‐arm star‐poly(ethylene glycol) (star‐PEG) coated silicon wafers and incubated with fluorescently labeled proteins. All PEG‐b‐PDLLA fibers showed no detectable adsorption of bovine serum albumin (BSA) independent of their composition while a dependence between hydrophobic block length was observed for streptavidin adsorption. Fibers of block copolymers with PDLLA blocks smaller than 39 kDa showed no adsorption of BSA or streptavidin, indicating good non‐fouling properties. Fibers were surface functionalized with Nε‐(+)‐biotinyl‐L‐lysine (biocytin) or RGD peptide by attaching the molecule to the PEG block during synthesis. Protein adsorption measurements, and the controlled interaction of biocytin with fluorescently labeled streptavidin, showed that the electrospun fibers were both resistant to protein adsorption and are functionalized. Fibroblast adhesion was contrasting between the unfunctionalized and RGD‐coupled electrospun fabrics, confirming that the surface of the fibers was functionalized. The PEG‐b‐PDLLA surface functionalized electrospun fibers are promising substrates for controlling cell–material interactions, particularly for tissue‐engineering applications. Biotechnol. Bioeng. 2008;101: 609–621. © 2008 Wiley Periodicals, Inc.
Anaerobic methanethiol degradation and methanogenic community analysis in an alkaline (pH 10) biological process for liquefied petroleum gas desulfurization
Authors: van Leerdam Robin C. , Bonilla‐Salinas Monica , de Bok Frank A.M. , Bruning H. , Lens Piet N.L. , Stams Alfons J.M. , Janssen Albert J.H. 
Published: April 2008

AbstractAnaerobic methanethiol (MT) degradation by mesophilic (30°C) alkaliphilic (pH 10) communities was studied in a lab‐scale Upflow Anaerobic Sludge Bed (UASB) reactor inoculated with a mixture of sediments from the Wadden Sea (The Netherlands), Soap Lake (Central Washington), and Russian soda lakes. MT degradation started after 32 days of incubation. During the first 252 days, complete degradation was achieved till a volumetric loading rate of 7.5 mmol MT/L/day, and sulfide, methane, and carbon dioxide were the main reaction products. Temporary inhibition of MT degradation occurred after MT peak loads and in the presence of dimethyl disulfide (DMDS), which is the autooxidation product of MT. From day 252 onwards, methanol was dosed to the reactor as co‐substrate at a loading rate of 3–6 mmol/L/day to stimulate growth of methylotrophic methanogens. Methanol was completely degraded and also a complete MT degradation was achieved till a volumetric loading rate of 13 mmol MT/L/day (0.77 mmol MT/gVSS/day). However, from day 354 till the end of the experimental run (day 365), acetate was formed and MT was not completely degraded anymore, indicating that methanol‐degrading homoacetogenic bacteria had partially outcompeted the methanogenic MT‐degrading archea. The archeal community in the reactor sludge was analyzed by DGGE and sequencing of 16S rRNA genes. The methanogenic archea responsible for the degradation of MT in the reactor were related to Methanolobus oregonensis. A pure culture, named strain SODA, was obtained by serial dilutions in medium containing both trimethyl amine and dimethyl sulfide (DMS). Strain SODA degraded MT, DMS, trimethyl amine, and methanol. Flow sheet simulations revealed that for sufficient MT removal from liquefied petroleum gas, the extraction and biological degradation process should be operated above pH 9. Biotechnol. Bioeng. 2008;101: 691–701. © 2008 Wiley Periodicals, Inc.
Synthesis and Application of Fluorescein‐ and Biotin‐Labeled Molecular Probes for the Chemokine Receptor CXCR4
Authors: Oishi Shinya , Masuda Ryo , Evans Barry , Ueda Satoshi , Goto Yukiko , Ohno Hiroaki , Hirasawa Akira , Tsujimoto Gozoh , Wang Zixuan , Peiper Stephen C. , Naito Takeshi , Kodama Eiichi , Matsuoka Masao , Fujii Nobutaka 
Published: April 2008

AbstractThe design, synthesis, and bioevaluation of fluorescence‐ and biotin‐labeled CXCR4 antagonists are described. The modification of D‐Lys8 at an ε‐amino group in the peptide antagonist Ac‐TZ14011 derived from polyphemusin II had no significant influence on the potent binding of the peptide to the CXCR4 receptor. The application of the labeled peptides in flow cytometry and confocal microscopy studies demonstrated the selectivity of their binding to the CXCR4 receptor, but not to CXCR7, which was recently reported to be another receptor for stromal cell‐derived factor 1 (SDF‐1)/CXCL12.
Percutaneous transcatheter communication between the pulmonary artery and atrium following an extra‐cardiac Fontan
Authors: Mehta C. , Jones T. , De Giovanni J.V. 
Published: April 2008

AbstractIn a nonfenestrated modified Fontan, transcatheter creation of a fenestration presents technical difficulties, especially with the extra‐cardiac modification where a Gore‐Tex tube is placed between the inferior caval vein and the pulmonary arteries. The authors describe an alternative approach to perforating the Gore‐Tex tube to create a fenestration by making a communication between the pulmonary artery and the atrial chamber, thus bridging the two circulations through native tissue. © 2008 Wiley‐Liss, Inc.