bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of liquid‐filled micelles based on an amphiphilic triblock copolymer
Authors: Jiang G. 
Published: August 2009

AbstractA series of novel amphiphilic triblock poly(ethylene glycol)‐b‐poly(2‐aminoethyl methacrylate hydrochloride)‐b‐poly(heptadeca‐fluorodecyl acrylate) (PEG‐b‐PAEMA‐b‐PHFDA) comprised of two hydrophilic PEG and PAEMA segments and one hydrophobic PHFDA segment was designed and synthesized. The structure of the triblock copolymer was characterized by 1H‐NMR and GPC analysis. The amphiphilic triblock copolymer was capable of self‐assembling into liquid‐filled micelles that consisted of PHFDA and liquid perfluorocarbons (PFCs) as the core and PEG as outer shell. PAEMA can be used as cross‐linking sites to increase the stability of the liquid‐filled micelles. The shape, size, and Acoustic properties of the obtained liquid‐filled micelles were investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of the spinning conditions on the structure and properties of polyamide 12/carbon nanotube composite fibers
Authors: Perrot Carine , Piccione Patrick M. , Zakri Cécile , Gaillard Patrice , Poulin Philippe 
Published: August 2009

AbstractThe inclusion of nanoparticles in polymer fibers is potentially useful for improving or bringing new properties such as mechanical strength, electrical conductivity, piezoresistivity, and flame retardancy. In this study, composite fibers made of polyamide 12 and multiwall carbon nanotubes were investigated. The fibers were spun via a melt‐spinning process and stretched at different draw ratios. The influence of several spinning factors, including spinning speed, extrusion rate, and draw ratio were investigated and correlated to the structure and properties of the fibers. X‐ray diffraction analyses and mechanical tests indicated that the spinning speed barely affected the structure and mechanical properties of the fibers under tension. The spinning speed, however, is critical for future industrial applications because it determines the possible production rates. By contrast, drawing during spinning or after spinning strongly affected the polymer chain alignment and fiber mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Needleless electrospinning. I. A comparison of cylinder and disk nozzles
Authors: Niu Haitao , Lin Tong , Wang Xungai 
Published: August 2009

AbstractIn this study, we demonstrated the needleless electrospinning of poly(vinyl alcohol) (PVA) nanofibers with two nozzles, a rotating disk and a cylinder, and examined the effect of the nozzle shape on the electrospinning process and resultant fiber morphology. The disk nozzle needed a relatively low applied voltage to initiate fiber formation, and the fibers were mainly formed on the top disk edge. Also, the PVA concentration had little influence on the disk electrospinning process (up to 11 wt %). In comparison, the cylinder electrospinning showed a higher dependence on the applied voltage and polymer concentration. The fibers were initiated from the cylinder ends first and then from the entire cylinder surface only if the applied voltage were increased to a certain level. With the same polymer solution, the critical voltage needed to generate nanofibers from the disk nozzle was lower than that needed to generate nanofibers from the cylinder. Both electrospinning systems could produce uniform nanofibers, but the fibers produced from the disk nozzle were finer than those from the cylinder when the operating conditions were the same. A thin disk (8 cm in diameter and 2 mm thick) could produce nanofibers at a rate similar to that of a cylinder of the same diameter but 100 times wider (i.e., 20 cm long). Finite element analysis of electric field profiles of the nozzles revealed a concentrated electric field on the disk edge. For the cylinder nozzle, an uneven distribution of the electric field intensity profile along the nozzle surface was observed. The field lines were mainly concentrated on the cylinder ends, with a much lower electric field intensity formed in the middle surface area. At the same applied voltage, the electric field intensity on the disk edge was much higher than that on the cylinder end. These differences in the electric field intensity profiles could explain the differences in the fiber fineness and rate of the nanofibers produced from these two nozzles. These findings will benefit the design and further development of large‐scale electrospinning systems for the mass production of nanofibers for advanced applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation of poly(vinyl amine)‐grafted crosslinked poly(vinyl alcohol) microspheres
Authors: Gao Baojiao , Lu Jinhua , Zhuang Rubin , Zhang Guohai 
Published: August 2009

AbstractCrosslinked poly(vinyl alcohol) (CPVA) microspheres were first prepared via the suspension polymerization of vinyl acetate and the alcoholysis of poly(vinyl acetate). Afterwards, a two‐step method involving graft polymerization and Hofmann degradation was used to prepare functional poly(vinyl amine)‐grafted crosslinked poly(vinyl alcohol) (PVAm–CPVA) microspheres, onto which poly(vinyl amine) (PVAm) macromolecules were grafted. The graft polymerization of acrylamide (AM) on CPVA microspheres was performed with cerium salt as the initiator in an acidic aqueous medium, resulting in polyacrylamide (PAM)‐grafted CPVA microspheres. Subsequently, the grafted PAM was transformed into PVAm via the Hofmann degradation reaction, and PVAm–CPVA microspheres were prepared. The effects of the main factors on the graft polymerization and Hofmann degradation were examined, and the reaction mechanisms were researched in depth. The experimental results showed that for the graft polymerization of AM on CPVA microspheres initiated by cerium salt, the acid concentration and the amount of cerium salt affected the grafting degree of PAM greatly. For the Hofmann degradation reaction of the grafted PAM, the amination degree of PVAm–CPVA microspheres was obviously affected by the amount of sodium hypochlorite in the presence of sodium hydroxide. The preliminary adsorption tests showed that PVAm–CPVA microspheres were multifunctional and had strong adsorption ability for Fe(III) ions by chelation action and for chromate ions (CrO) by strong electrostatic interactions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Antipolyelectrolyte superabsorbing nanocomposites: Synthesis and properties
Authors: Pourjavadi A. , Kheirabadi M. , Zohuriaan‐Mehr M. J. , Kabiri K. 
Published: August 2009

AbstractNovel polyampholytic superabsorbing nanocomposites based on the zwitterionic sulfobetaine monomer [3‐(methacrylamido)propyl)]dimethyl(3‐sulfopropyl)ammonium hydroxide were synthesized through in situ polymerization in aqueous solution with different contents of an organo‐modified clay (OMMT, Cloisite 30B). Structural and thermomechanical properties of hydrogels were characterized by FT‐IR, XRD, and DMTA, respectively. Swollen gel strength of hydrogels was determined by a rheological method. Storage modulus of the hydrogels was considerably improved in comparison with its the clay‐free counterpart. The nanocomposite hydrogel containing 15% OMMT possessed the highest gel strength. The glass transition temperature was increased from 58.4 to 67.0°C for the clay‐free and nanocomposite hydrogel containing 8% OMMT, respectively. The swelling behavior of the hydrogel in various salt solutions was investigated. Antipolyelectrolyte behavior was observed with enhancement of concentration of mono‐ and multivalent salts. Swelling in the various pH media was nearly pH‐independent over a wide range of pH. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Evaluation of water sorption behavior and in vitro blood compatibility of polyvinyl alcohol based magnetic bionanocomposites
Authors: Bajpai A. K. , Gupta Rashmi 
Published: August 2009

AbstractIn recent past magnetic bionanocomposites have shown potential in biomedical applications mainly due to their superparamagnetic and biocompatible nature. They have also established themselves as a promising class of hybrid organic–inorganic materials derived from polymers and organic/inorganic fillers. In this study biocompatible nanocomposites were prepared by in situ synthesis of magnetic nanoparticles within the polyvinyl alcohol‐grafted‐polymethyl methacrylate hydrogels and characterized by techniques such as FT‐IR, scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, and differential scanning calorimetry. The bionanocomposites were evaluated for water sorption behavior and in vitro biocompatibility by performing thrombus formation and hemolysis tests. The influence of chemical composition of the grafted hydrogel was investigated on water sorption behavior and in vitro blood compatibility of magnetic bionanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Improved mechanical properties and structure of polypropylene pipe prepared under vibration force field
Authors: Chen Kai‐Yuan , Zhou Nan‐Qiao , Liu Bin , Jin Gang 
Published: August 2009

AbstractThe polypropylene (PP) pipes were prepared using a self‐made electromagnetic dynamic plasticating extruder, which introduced a vibration force field into the whole plasticating and extrusion process by the axial vibration of the screw. The effects of the vibration frequency and the vibration amplitude on the mechanical properties and microstructure of PP pipes were investigated using bursting pressure testing, tensile testing, impact testing, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD). The mechanical properties testing showed that the circumferential strength of PP pipes increased significantly, and the biaxial self‐reinforcement pipes could be obtained. Also, the impact strength was improved. When compared with the conventional static extruded specimens, the maximum increase of bursting pressure, tensile yield strength, and impact strength were 27.03%, 7.3%, and 16.2%, respectively. DSC and WAXD analysis showed that the PP pipes obtained by vibration plasticating extrusion (VPE) had higher crystallinity, higher melting temperature, more perfect crystals, and smaller crystal sizes, but no new polymeric crystalline peak appeared. The improvement of mechanical properties of the PP pipes prepared by VPE was attributed to the higher crystallinity and the improvement of the molecular orientation and of the crystalline morphology under the action of the vibration force field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Hirsch index rankings require scaling and higher moment
Authors: Bletsas Aggelos , Sahalos John N. 
Published: August 2009

AbstractSimple bibliometric indicators, such as average number of citations per publication per researcher, or the recently proposed Hirsch index (h‐index), are nowadays tracked by online repositories, including Web of Science (WOS), and often affect critical decision making. This work proposes appropriate scaling of the h‐index based on its probability distribution that is calculated for any underlying citation distribution. The proposed approach outperforms existing index estimation models that have focused on the expected value only (i.e., first moment). Furthermore, it is shown that average number of citations per publication per scientific field, total number of publications per researcher, as well as researcher's h‐index measured value, expected value, and standard deviation constitute the minimum information required for meaningful h‐index ranking campaigns; otherwise contradicting ranking results emerge. This work may potentially shed light to (current or future) large‐scale, h‐index‐based bibliometric evaluations.
An indicator of research front activity: Measuring intellectual organization as uncertainty reduction in document sets
Authors: Lucio‐Arias Diana , Leydesdorff Loet 
Published: August 2009

AbstractWhen using scientific literature to model scholarly discourse, a research specialty can be operationalized as an evolving set of related documents. Each publication can be expected to contribute to the further development of the specialty at the research front. The specific combinations of title words and cited references in a paper can then be considered as a signature of the knowledge claim in the paper: New words and combinations of words can be expected to represent variation, while each paper is at the same time selectively positioned into the intellectual organization of a field using context‐relevant references. Can the mutual information among these three dimensions—title words, cited references, and sequence numbers—be used as an indicator of the extent to which intellectual organization structures the uncertainty prevailing at a research front? The effect of the discovery of nanotubes (1991) on the previously existing field of fullerenes is used as a test case. Thereafter, this method is applied to science studies with a focus on scientometrics using various sample delineations. An emerging research front about citation analysis can be indicated.
Metabolism, oral bioavailability and pharmacokinetics of chemopreventive kaempferol in rats
Authors: Barve Avantika , Chen Chi , Hebbar Vidya , Desiderio Joseph , Saw Constance Lay‐Lay , Kong Ah‐Ng 
Published: August 2009

AbstractThe purpose of this study was to compare the hepatic and small intestinal metabolism, and to examine bioavailability and gastro‐intestinal first‐pass effects, of kaempferol in rats. Liver and small intestinal microsomes fortified with either NADPH or UDPGA were incubated with varying concentrations of kaempferol for up to 120 min. Based on the values of the kinetic constants (Km and Vmax), the propensity for UDPGA‐dependent conjugation compared with NADPH‐dependent oxidative metabolism was higher for both hepatic and small intestinal microsomes. Male Sprague‐Dawley rats were administered kaempferol intravenously (i.v.) (10, 25 mg/kg) or orally (100, 250 mg/kg). Gastro‐intestinal first‐pass effects were observed by collecting portal blood after oral administration of 100 mg/kg kaempferol. Pharmacokinetic parameters were obtained by non‐compartmental analysis using WinNonlin. After i.v. administration, the plasma concentration–time profiles for 10 and 25 mg/kg were consistent with high clearance (∼3 L/hr/kg) and large volumes of distribution (8–12 L/hr/kg). The disposition was characterized by a terminal half‐life value of 3–4 h. After oral administration the plasma concentration–time profiles demonstrated fairly rapid absorption (tmax∼1–2 h). The area under the curve (AUC) values after i.v. and oral doses increased approximately proportional to the dose. The bioavailability (F) was poor at ∼2%. Analysis of portal plasma after oral administration revealed low to moderate absorption. Taken together, the low F of kaempferol is attributed in part to extensive first‐pass metabolism by glucuronidation and other metabolic pathways in the gut and in the liver. Copyright © 2009 John Wiley & Sons, Ltd.
When experience is better than description: Time delays and complexity
Authors: Lejarraga Tomás 
Published: August 2009

AbstractThe dominant sampling paradigm of experience‐based choice is extended by exploring two realistic aspects of decisions. First, frequency judgments were studied in situations involving a delay between information acquisition and judgment. This time gap undermines recall from working memory and favors the natural human capacity to encode frequencies effortlessly. Deferred judgments from experience were found to be more accurate than judgments from description, both for absolute and rank‐order judgments. Second, task complexity was varied. This showed that—as decision tasks become more complex—participants are willing to trade‐off detailed but complex descriptive information for less accurate but simpler information sampled from experience. Moreover, there were no individual differences due to numerical/rational abilities. Results from the two studies suggest that information obtained from experience can be more valuable than descriptive information in that it can both lead to better frequency judgments in deferred tasks and simplify cognitive representations of complex choice tasks. Copyright © 2009 John Wiley & Sons, Ltd.
Lack of a co‐promotion effect of 60 Hz circularly polarized magnetic fields on spontaneous development of lymphoma in AKR mice
Authors: Chung Moon‐Koo , Yu Wook‐Joon , Kim Yong‐Bum , Myung Sung‐Ho 
Published: August 2009

AbstractThe present study was conducted to investigate the possible effect of 60 Hz circularly polarized magnetic fields (MFs) as promoters of genetically initiated lymphoma in AKR mice. One hundred sixty female animals were divided into four different groups. They were exposed to four different intensities of circularly polarized MFs. Animals received exposure to 60 Hz circularly polarized MF at field strengths (rms‐value) of 0 µT (sham control, T1, Group I), 5 µT(T2, Group II), 83.3 µT (T3, Group III), or 500 µT(T4, Group IV), for 21 h/day from the age of 4–6 weeks to the age of 44–46 weeks. There were no exposure‐related changes in mean survival time, clinical signs, body weights, hematological values, micronucleus assay, gene expression arrays, analysis of apoptosis, and necropsy findings. At histopathological examination, lymphoma was seen in all the groups. The tumor incidence was 31/40(78%), 30/40(75%), 32/40(80%), and 31/40(78%) in sham control, 5, 83.3, and 500 µT groups, respectively. However, there were no differences in the tumor incidence between the sham control (T1) and circularly polarized MF exposure groups (T2–T4). In conclusion, there was no evidence that exposure to 60 Hz circularly polarized MF strengths up to 500 µT promoted lymphoma in AKR mice. Bioelectromagnetics 31:130–139, 2010. © 2009 Wiley‐Liss, Inc.
Making the right connections: biological networks in the light of evolution
Authors: Knight Christopher G. , Pinney John W. 
Published: August 2009

AbstractOur understanding of how evolution acts on biological networks remains patchy, as is our knowledge of how that action is best identified, modelled and understood. Starting with network structure and the evolution of protein–protein interaction networks, we briefly survey the ways in which network evolution is being addressed in the fields of systems biology, development and ecology. The approaches highlighted demonstrate a movement away from a focus on network topology towards a more integrated view, placing biological properties centre‐stage. We argue that there remains great potential in a closer synergy between evolutionary biology and biological network analysis, although that may require the development of novel approaches and even different analogies for biological networks themselves.
Gene networks and liar paradoxes
Authors: Isalan Mark 
Published: August 2009

AbstractNetwork motifs are small patterns of connections, found over‐represented in gene regulatory networks. An example is the negative feedback loop (e.g. factor A represses itself). This opposes its own state so that when ‘on’ it tends towards ‘off’ – and vice versa. Here, we argue that such self‐opposition, if considered dimensionlessly, is analogous to the liar paradox: ‘This statement is false’. When ‘true’ it implies ‘false’ – and vice versa. Such logical constructs have provided philosophical consternation for over 2000 years. Extending the analogy, other network topologies give strikingly varying outputs over different dimensions. For example, the motif ‘A activates B and A. B inhibits A’ can give switches or oscillators with time only, or can lead to Turing‐type patterns with both space and time (spots, stripes or waves). It is argued here that the dimensionless form reduces to a variant of ‘The following statement is true. The preceding statement is false’. Thus, merely having a static topological description of a gene network can lead to a liar paradox. Network diagrams are only snapshots of dynamic biological processes and apparent paradoxes can reveal important biological mechanisms that are far from paradoxical when considered explicitly in time and space.
Revisiting the neighbor exclusion model and its applications
Authors: Rocha Marcio S. 
Published: August 2009

AbstractWe review the neighbor exclusion model and some of its applications to analyze the binding data of DNA‐ligand complexes. We revisit the closed form of the model developed by McGhee and von Hippel in 1974, showing that this classic model can be used to help studying the behavior of DNA contour and persistence lengths when interacting with intercalating ligands. We present methods to quantitatively analyze the variation of these two quantities, allowing one to determine important parameters of the interaction such as the intrinsic binding constant and the exclusion number of the ligand. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 1–7, 2010.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
Case study and application of process analytical technology (PAT) towards bioprocessing: Use of tryptophan fluorescence as at‐line tool for making pooling decisions for process chromatography
Authors: Rathore Anurag S. , Li Xiaohui , Bartkowski Wojciech , Sharma Ashutosh , Lu Yuefeng 
Published: September 2009

AbstractProcess analytical technology (PAT) has been gaining momentum in the biopharmaceutical community due to the potential for continuous real time quality assurance resulting in improved operational control and compliance. Two imperatives for implementing any PAT tool are that “variability is managed by the process” and “product quality attributes can be accurately and reliably predicted over the design space established for materials used, process parameters, manufacturing, environmental, and other conditions.” Recently, we have been examining the feasibility of applying different analytical tools to bioprocessing unit operations. We have previously demonstarted that commercially available online‐high performance liquid chromatography and ultra performance liquid chromatography systems can be used for analysis that can facilitate real‐time decisions for column pooling based on product quality attributes (Rathore et al., 2008a,b). In this article, we review an at‐line tool that can be used for pooling of process chromatography columns. We have demonstrated that our tryptophan fluorescence method offers a feasible approach and meets the requirements of a PAT application. It is significantly faster than the alternative of fractionation, offline analysis followed by pooling. Although the method as presented here is not an online method, this technique may offer better resolution for certain applications and may be a more optimal approach as it is very conducive to implementation in a manufacturing environment. This technique is also amenable to be used as an online tool via front face fluorescence measurements done concurrently with product concentration determination by UV. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009