bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and colloidal stability of poly(N‐isopropylacrylamide) microgels with different ionic groups on their surfaces
Authors: Zha Liusheng , Li Lan , Bao Laiyan 
Published: December 2006

AbstractTemperature‐sensitive poly(N‐isopropylacry‐lamide) (PNIPAM) microgels with sulfate, amidino, or carboxylic groups on their surfaces, were synthesized by precipitation polymerization based on ammonium persulfate (APS), 2,2′‐azobis(amidinopropane) dihydrochloride (V50), or 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) as initiator, respectively. Their particle sizes and swelling ratios depended on the reaction pH due to the pH dependence of the ionization degree of the decomposed fragments originating from the initiators and their hydrophilicity–hydrophobicity. The more hydrophobic initiators partitioned into the interior of the PNIPAM microgels under certain pH conditions initiated the crosslinking reaction between the PNIPAM chains, leading to higher crosslinking density of the microgels resulting in their smaller swelling ratio. pH dependence of surface charge density of the microgels with amidino groups or carboxylic acid groups on their surfaces was evidenced by the variation of their ζ‐potentials as a function of pH. Correspondingly, due to their pH dependence of electrostatic repulsive effect, the colloidal stability of the microgels with amidine groups or carboxylic acid groups on their surfaces was dependent on the pH value of dispersion medium. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3893–3898, 2007
Wear and mechanical properties of reactive thermotropic liquid crystalline polymer/unsaturated polyester/glass fiber hybrid composites
Authors: Yu Xianbao , Wei Chun , Xu Deng , Lu Chihua , Yu Jinhong , Lu Shaorong 
Published: December 2006

AbstractTo improve the performance of unsaturated polyester (UP) under cold‐heat alternate temperature, self‐synthesized reactive thermotropic liquid crystalline polymer (TLCP)‐methacryloyl copolymer (LCMC), UP, and glass fiber (GF) hybrid composites was prepared by molding technology. The apparent activation energy and crystal behavior analysis of LCMC/UP blends were investigated by Differential scanning calorimetry and X‐ray diffraction (XRD), respectively, the results showed that the addition of LCMC can reduce apparent activation energy and accelerate the curing reaction of UP, the XRD analysis indicated that the crystal phase of LCMC still exist in the blends after blending with UP. The effect of LCMC content on the properties of LCMC/UP/GF hybrid composites such as impact strength, bending strength, and ring‐on‐block wear were also investigated through static mechanical tests and wear tests. The mechanical properties of hybrid composites increased significantly because of the addition of LCMC. The wear tests showed that LCMC can improve the wear resistance of the UP/GF/LCMC hybrid composites even though the content of LCMC was at a relatively low level (5–7.5 wt %). This makes it possible to develop novel kind of UP‐based materials with good wear resistance for various applications. The Worn surface was observed by scanning electron microscopy (SEM) and the mechanism for the improvement is discussed in this paper. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3899–3906, 2007
Comparative behavior of PVA/PAN and PVA/PES composite pervaporation membranes in the pervaporative dehydration of caprolactam
Authors: Zhang Lei , Yu Ping , Luo Yunbai 
Published: December 2006

AbstractFlat‐sheet composite membranes were developed by the traditional phase inversion technique using poly;(vinyl alcohol) (PVA). PVA composite pervaporation (PV) membranes were prepared with crosslinked PVA selective layer and porous polyacrylonitrile (PAN) and polyether sulfone (PES) substrate layer material as supports for separating heat sensitivity substance ε‐caprolactam (CPL) from CPL/water mixtures. Glutaraldehyde was used as crosslinking agent. The effect of the composition of glutaraldehyde on membrane stability and structure were investigated. The operating parameters, such as feed concentration and operating temperature, remarkably affected PV performance of the composite membranes. The composite membranes with PVA casted on PAN (PVA/PAN) showed superior PV performance than that casted on PES (PVA/PES). This study has also shown that the type of porous support plays an important role in the PV performance. As a result, this work has presented the information needed of the behavior of PV membranes for dehydration applications of industrial caprolactam. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4005–4011, 2007
Dynamic mechanical properties and morphology of high‐density polyethylene/CaCO3 blends with and without an impact modifier
Authors: Yang Yu‐Lin , G'Sell Christian , Hiver Jean‐Marie , Bai Shu‐Lin 
Published: December 2006

AbstractDynamic mechanical analysis and differential scanning calorimetry were used to investigate the relaxations and crystallization of high‐density polyethylene (HDPE) reinforced with calcium carbonate (CaCO3) particles and an elastomer. Five series of blends were designed and manufactured, including one series of binary blends composed of HDPE and amino acid treated CaCO3 and four series of ternary blends composed of HDPE, treated or untreated CaCO3, and a polyolefin elastomer [poly(ethylene‐co‐octene) (POE)] grafted with maleic anhydride. The analysis of the tan δ diagrams indicated that the ternary blends exhibited phase separation. The modulus increased significantly with the CaCO3 content, and the glass‐transition temperature of POE was the leading parameter that controlled the mechanical properties of the ternary blends. The dynamic mechanical properties and crystallization of the blends were controlled by the synergistic effect of CaCO3 and maleic anhydride grafted POE, which was favored by the core–shell structure of the inclusions. The treatment of the CaCO3 filler had little influence on the mechanical properties and morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3907–3914, 2007
Synthesis of conducting polyaniline/TiO2 composite nanofibres by one‐step in situ polymerization method
Authors: Bian Chaoqing , Yu Yijun , Xue Gi 
Published: December 2006

AbstractConducting polyaniline (PANI)/titanium dioxide (TiO2) composite nanofibres with an average diameter of 80–100 nm were prepared by one‐step in situ polymerization method in the presence of anatase nano‐TiO2 particles, and were characterized via Fourier‐transform infrared spectra, UV/vis spectra, wide‐angle X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy, as well as conductivity and cyclic voltammetry. The formation mechanism of PANI/TiO2 composite nanofibres was also discussed. This composite contained ∼ 65% conducting PANI by mass, with a conductivity of 1.42 S cm−1 at 25°C, and the conductivity of control PANI was 2.4 S cm−1 at 25°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Surface‐initiated atom transfer radical polymerization from Mg(OH)2 nanoparticles to prepare the well‐defined polymer‐Mg(OH)2 nanocomposites
Authors: Chang Ming‐Jen , Tsai Jen‐Yun , Chang Chia‐Wei , Chang Hwai‐Ming , Jiang George J. 
Published: December 2006

AbstractWell‐defined polymer‐Mg(OH)2 nanocomposites were prepared by atom transfer radical polymerization (ATRP). The ATRP initiators were covalently attached to the Mg(OH)2 by esterification of 2‐chloropropionyl chloride with hydroxyl group. The amount of polymer grafted from Mg(OH)2 can be controlled using a different catalyst system and adding a small amount of polar solvent. The well‐defined diblock copolymer, consisting of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) were synthesized. The products were characterized by nuclear magnetic resonance, Fourier transform infrared, differential scanning calorimetry, and thermal gravimetric analysis. The morphologies of PS/PMMA and PS/PMMA/Mg(OH)2‐g‐PS‐b‐PMMA blends are compared by using a scanning electron microscope. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3680–3687, 2007
Dynamic h‐index: The Hirsch index in function of time
Authors: Egghe Leo 
Published: December 2006

AbstractWhen there are a group of articles and the present time is fixed we can determine the unique number h being the number of articles that received h or more citations while the other articles received a number of citations which is not larger than h. In this article, the time dependence of the h‐index is determined. This is important to describe the expected career evolution of a scientist's work or of a journal's production in a fixed year. We use the earlier established cumulative nth citation distribution. We show that

where a is the aging rate, α is the exponent of Lotka's law of the system, and T is the total number of articles in the group. For t = +∞ we refind the steady state (static) formula $h = T^{{1 \over \alpha }}$, which we proved in a previous article. Functional properties of the above formula are proven. Among several results we show (for α, a, T fixed) that h is a concavely increasing function of time, asymptotically bounded by $T^{{1 \over \alpha }}$.
A library or just another information resource? A case study of users' mental models of traditional and digital libraries
Authors: Makri Stephann , Blandford Ann , Gow Jeremy , Rimmer Jon , Warwick Claire , Buchanan George 
Published: December 2006

AbstractA user's understanding of the libraries they work in, and hence of what they can do in those libraries, is encapsulated in their “mental models” of those libraries. In this article, we present a focused case study of users' mental models of traditional and digital libraries based on observations and interviews with eight participants. It was found that a poor understanding of access restrictions led to risk‐averse behavior, whereas a poor understanding of search algorithms and relevance ranking resulted in trial‐and‐error behavior. This highlights the importance of rich feedback in helping users to construct useful mental models. Although the use of concrete analogies for digital libraries was not widespread, participants used their knowledge of Internet search engines to infer how searching might work in digital libraries. Indeed, most participants did not clearly distinguish between different kinds of digital resource, viewing the electronic library catalogue, abstracting services, digital libraries, and Internet search engines as variants on a theme.
Overcoming knowledge management challenges during ERP implementation: The need to integrate and share different types of knowledge
Authors: Pan Shan L. , Newell Sue , Huang Jimmy , Galliers Robert D. 
Published: December 2006

AbstractIn this article, the author examines an enterprise resource planning (ERP) adoption process in a particular case setting to explore the knowledge management challenges encountered, specifically challenges related to the sharing and integration of knowledge, and the ways that social capital is used to overcome these challenges. More specifically, the author relates the different sources and effects of social capital to the different implementation phases, with their differing knowledge management challenges. By doing so, he highlights the relative importance of the bridging and bonding aspects of social capital that vary during different phases because of the different types of knowledge that become more or less important over the lifecycle of the project—embrained, embodied, encultured, embedded, and encoded.
RhI‐Catalyzed Bimolecular Cyclization between Two Different 1,5‐Bisallenes: A Combinatorial One‐Step Approach to Heterosteroids and Mechanistic Implications
Authors: Ma Shengming , Lu Lianghua 
Published: December 2006

AbstractIn this paper, a bimolecular‐cyclization reaction between two different bis(allene)s with at least one heteroatom as the tether under the catalysis of trans‐[RhCl(CO)(PPh3)2] is described. This protocol provides an efficient entry to different heterocyclic 18,19‐norsteroid‐like scaffolds. The tricyclic product was formed highly selectively from the cyclization reaction of bis(2,3‐butadienyl)sulfide with dimethyl 2‐bis(2′,3′‐butadienyl)malonate, which sheds light on the mechanism involving the metalla‐[4.3.0]‐bicyclic intermediate formed by the cyclometallation of the terminal and the internal C=C bonds of each of the two allene moieties in 2‐bis(2′,3′‐butadienyl)malonate.
Highly Efficient Non‐Palladium‐Catalyzed Controlled Synthesis and X‐ray Analysis of Functionalized 1,2‐Diaryl‐, 1,2,3‐Triaryl‐, and 1,2,3,4‐Tetraarylbenzenes
Authors: Goel Atul , Singh Fateh Veer , Dixit Manish , Verma Deepti , Raghunandan Resmi , Maulik Prakas R. 
Published: December 2006

AbstractA general, two‐step, highly efficient synthesis of 1,2‐diaryl‐, 1,2,3‐triaryl‐, and 1,2,3,4‐tetraarylbenzenes from simple stitching of α‐oxo‐ketene‐S,S‐acetals and active methylene compounds via a lactone intermediate is described. This procedure offers easy access to highly functionalized arylated benzenes that contain sterically demanding groups in good to excellent yields. The novelty of the procedure lies in the construction of aromatic compounds with the desired conformational flexibility along the molecular axis in a transition‐metal‐free environment through easily accessible precursors. Crystal analysis of these arylated benzene scaffolds showed that the peripheral aryl rings are arranged in a propeller‐like fashion with respect to the central benzene ring. Examination of the crystal packing in the structure of a 1,2,3,4‐tetraarylbenzene revealed an N⋅⋅⋅π interaction between molecules related by a two‐fold screw axis running in the direction of the a axis. Interestingly, the repeating array of N⋅⋅⋅π interactions around the axis of this 1,2,3,4‐tetraarylbenzene forces the molecules into a helical pattern.
Microparticles and nanoparticles for drug delivery
Authors: Kohane Daniel S. 
Published: December 2006

AbstractParticulate drug delivery systems have become important in experimental pharmaceutics and clinical medicine. The distinction is often made between micro‐ and nanoparticles, being particles with dimensions best described in micrometers and nanometers respectively. That size difference entails real differences at many levels, from formulation to in vivo usage. Here I will discuss those differences and provide examples of applications, for local and systemic drug delivery. I will outline a number of challenges of interest in particulate drug delivery. Biotechnol. Bioeng. 2007;96: 203–209. © 2006 Wiley Periodicals, Inc.
Dynamic modeling of an enzymatic membrane reactor for the treatment of xenobiotic compounds
Authors: López C. , Moreira M.T. , Feijoo G. , Lema J.M. 
Published: December 2006

AbstractA membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane was set up for the enzymatic oxidation of xenobiotic compounds. The azo dye Orange II was selected for the model compound and manganese peroxidase for the oxidative enzyme. The ligninolytic cycle was initiated and maintained by the controlled addition of all factors (reactants, mediators, and stabilizers) at suitable rates. Considering the distinctiveness of this process, in which the substrate to be oxidized is not the primary substrate for the enzyme, a kinetic model was developed. The azo dye concentration and hydrogen peroxide addition rate were found to be the main factors affecting the process. The reaction kinetics was defined using a Michaelis–Menten model with respect to the Orange II concentration and a first‐order linear dependence relative to the H2O2 addition rate. The dynamic model, which takes into account both the kinetics and the hydraulics of the system, was validated by comparing the experimental results in continuous operation under steady and non‐steady state to model predictions. In particular, the model predicted the behavior of the system when unexpected alterations in steady‐state operation occurred. Furthermore, the model allowed us to obtain the most appropriate H2O2/Orange II ratio in the feed to maximize the process efficiency. Biotechnol. Bioeng. 2007; 97: 1128–1137. © 2006 Wiley Periodicals, Inc.
Mineral and iron oxidation at low temperatures by pure and mixed cultures of acidophilic microorganisms
Authors: Dopson Mark , Halinen Anna‐Kaisa , Rahunen Nelli , Özkaya Bestamin , Sahinkaya Erkan , Kaksonen Anna H. , Lindström E. Börje , Puhakka Jaakko A. 
Published: December 2006

AbstractAn enrichment culture from a boreal sulfide mine environment containing a low‐grade polymetallic ore was tested in column bioreactors for simulation of low temperature heap leaching. PCR‐denaturing gradient gel electrophoresis and 16S rRNA gene sequencing revealed the enrichment culture contained an Acidithiobacillus ferrooxidans strain with high 16S rRNA gene similarity to the psychrotolerant strain SS3 and a mesophilic Leptospirillum ferrooxidans strain. As the mixed culture contained a strain that was within a clade with SS3, we used the SS3 pure culture to compare leaching rates with the At. ferrooxidans type strain in stirred tank reactors for mineral sulfide dissolution at various temperatures. The psychrotolerant strain SS3 catalyzed pyrite, pyrite/arsenopyrite, and chalcopyrite concentrate leaching. The rates were lower at 5°C than at 30°C, despite that all the available iron was in the oxidized form in the presence of At. ferrooxidans SS3. This suggests that although efficient At. ferrooxidans SS3 mediated biological oxidation of ferrous iron occurred, chemical oxidation of the sulfide minerals by ferric iron was rate limiting. In the column reactors, the leaching rates were much less affected by low temperatures than in the stirred tank reactors. A factor for the relatively high rates of mineral oxidation at 7°C is that ferric iron remained in the soluble phase whereas, at 21°C the ferric iron precipitated. Temperature gradient analysis of ferrous iron oxidation by this enrichment culture demonstrated two temperature optima for ferrous iron oxidation and that the mixed culture was capable of ferrous iron oxidation at 5°C. Biotechnol. Bioeng. 2007; 97: 1205–1215. © 2006 Wiley Periodicals, Inc.
Kinetics of iron oxidation by Leptospirillum ferriphilum dominated culture at pH below one
Authors: Özkaya Bestamin , Sahinkaya Erkan , Nurmi Pauliina , Kaksonen Anna H. , Puhakka Jaakko A. 
Published: December 2006

AbstractThe kinetics of ferrous iron oxidation by Leptospirillum ferriphilum (L. ferriphilum) dominated culture was studied in the concentration range of 0.1–20 g Fe2+/L and the effect of ferric iron (0–60 g Fe3+/L) on Fe2+ oxidation was investigated at pH below one. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes followed by partial sequencing confirmed that the bacterial community was dominated by L. ferriphilum. In batch assays, Fe2+ oxidation started without lag phase and the oxidation was completed within 1 to 60 h depending on the initial Fe2+ concentration. The specific Fe2+ oxidation rates increased up to around 4 g/L and started to decrease at above 4 g/L. This implies substrate inhibition of Fe2+ oxidation at higher concentrations. Haldane equation fitted the experimental data reasonably well (R2 = 0.90). The maximum specific oxidation rate (qm) was 2.4 mg/mg VS · h, and the values of the half saturation (Ks) and self inhibition constants (Ki) were 413 and 8,650 mg/L, respectively. Fe2+ oxidation was competitively inhibited by Fe3+ and the competitive inhibition constant (Kii) was 830 mg/L. The time required to reach threshold Fe2+ concentration was around 1 day and 2.3 days with initial Fe3+ concentration of 5 and 60 g/L, respectively. The threshold Fe2+ concentration, below which no further Fe2+ oxidation occurred, linearly increased with increasing initial Fe2+ and Fe3+ concentrations. Fe2+ oxidation proceeds by L. ferriphilum dominated culture at pH below 1 even in the presence of 60 g Fe3+/L. This indicates potential of using and biologically regenerating concentrated Fe3+ sulfate solutions required, for example, in indirect tank leaching of ore concentrates. Biotechnol. Bioeng. 2007; 97: 1121–1127. © 2006 Wiley Periodicals, Inc.
Simultaneous positioning of cells into two‐dimensional arrays using ultrasound
Authors: Neild Adrian , Oberti Stefano , Radziwill Gerald , Dual Jürg 
Published: December 2006

AbstractContactless simultaneous positioning of micrometer‐sized particles in suspension (e.g., copolymer beads, living cells, silicon microparts) can be performed using ultrasound. Current devices are capable of collecting particles into planes or lines by exciting a resonance in the fluid by means of a piezoelectric transducer located beneath the fluidic cavity and are designed such that a one‐dimensional pressure field is created. The focus of this work is to collect cells in distinct point locations for potential drug screening array applications. A device to create two‐dimensional arrays of cells within a micromachined chamber is described. The chamber is etched into a silicon wafer and sealed with glass; on the underside of the silicon layer a piezoelectric actuator is attached. A signal is applied to each of two orthogonally aligned strips electrodes defined on the surface of the piezoelectric plate. These two strip electrodes create independently addressable approximately one‐dimensional pressure fields. It is shown that by applying the same signal to each electrode a diagonally aligned grid of cells can be produced. However, the independence of the two electrodes allows the application of two signals with slightly different frequencies to be applied which creates a grid of circular cell clumps highly suitable for the identified application. Biotechnol. Bioeng. 2007; 97: 1335–1339. © 2006 Wiley Periodicals, Inc.
Cooperativity and saturation in biochemical networks: A saturable formalism using Taylor series approximations
Authors: Sorribas Albert , Hernández‐Bermejo Benito , Vilaprinyo Ester , Alves Rui 
Published: December 2006

AbstractCooperative and saturable systems are common in molecular biology. Nevertheless, common canonical formalisms for kinetic modeling that are theoretically well justified do not have a saturable form. Modeling and fitting data from saturable systems are widely done using Hill‐like equations. In practice, there is no theoretical justification for the generalized use of these equations, other than their ability to fit experimental data. Thus it is important to find a canonical formalism that is (a) theoretically well supported, (b) has a saturable functional form, and (c) can be justifiably applicable to any biochemical network. Here we derive such a formalism using Taylor approximations in a special transformation space defined by power‐inverses and logarithms of power‐inverses. This formalism is generalized for processes with n‐variables, leading to a useful mathematical representation for molecular biology: the Saturable and Cooperative Formalism (SC formalism). This formalism provides an appropriate representation that can be used for modeling processes with cooperativity and saturation. We also show that the Hill equation can be seen as a special case within this formalism. Parameter estimation for the SC formalism requires information that is also necessary to build Power‐Law models, Metabolic Control Analysis descriptions or (log)linear and Lin‐log models. In addition, the saturation fraction of the relevant processes at the operating point needs to be considered. The practical use of the SC formalism for modeling is illustrated with a few examples. Similar models are built using different formalisms and compared to emphasize advantages and limitations of the different approaches. Biotechnol. Bioeng. 2007; 97: 1259–1277. © 2006 Wiley Periodicals, Inc.