bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glial cell line‐derived neurotrophic factor promotes olfactory ensheathing cells migration
Authors: Cao Li , Su Zhida , Zhou Qiang , Lv Baolai , Liu Xiujie , Jiao Li , Li Zhihua , Zhu Yanling , Huang Zhihui , Huang Aijun , He Cheng 
Published: August 2006

AbstractOlfactory ensheathing cells (OECs) are a unique type of macroglia with axonal growth‐promoting properties. The migrating ability of OECs in CNS is essential for neural regeneration. However, little is known about the extracellular and intracellular factors that regulate OEC migration. In the present study, we examined the effects of glial cell line‐derived neurotrophic factor (GDNF) on OECs migration. Initially, the “scratch” migration assay, Boyden chamber assay, and explant migration assay showed that GDNF could promote OECs migration in vitro. Treatment of OECs with GDNF also induced cytoskeleton reorganization and up‐regulated expression of cytoskeleton proteins. GDNF‐induced OECs migration was demonstrated depending on GFRα‐1 and Ret receptor, and activation of JNK and Src signaling cascades. Furthermore, GDNF was found to promote implanted OECs migration in a spinal cord hemisection injury model. Together, we report, to our knowledge for the first time, that GDNF stimulate OECs migration in vitro and in vivo. © 2006 Wiley‐Liss, Inc.
Experimental results of the tracheoesophageal tissue connector for improved fixation of shunt valves in laryngectomized patients
Authors: Ten Hallers E. J. O. , Marres Henri A. M. , van der Houwen Eduard B. , Jansen John A. , Rakhorst Gerhard , Schutte Harm K. , van Kooten Theo G. , van Loon Jan‐Paul , Verkerke Gijsbertus J. 
Published: August 2006

AbstractBackground.After total laryngectomy and voice rehabilitation using a tracheoesophageal shunt valve, patients often have valve‐related complications such as leakage. To solve these problems, a tracheoesophageal tissue connector (TE‐TC) was devised to serve as an interface between the patient's tissue (trachea and esophagus) and the shunt valve.Methods.The TE‐TC is a permucosal connection constructed from a titanium ring (filled with a silicon rubber plug) combined with polypropylene or titanium mesh. After implantation in adult goats for 12 weeks the implants were submitted to histologic investigation.Results.Firm implant fixation was achieved. In nearly all (18/19), no signs of infection of the implant were seen; 11 of 19 animals died before the end of the experiment owing to complications not related to the implant.Conclusions.The TE‐TC is a new device with potential in the solution for fixation‐related problems in tracheoesophageal voice rehabilitation. © 2006 Wiley Periodicals, Inc. Head Neck, 2006
New approach to large‐volume injection in reversed‐phase high performance liquid chromatography: Determination of atrazine and hydroxyatrazine in soil samples
Authors: Hutta Milan , Chalányová Mária , Halko Radoslav , Góra Róbert , Rybár Ivan , Pajchl Marek , Dokupilová Svetlana 
Published: August 2006

AbstractA well established method of direct injection of larger than conventional sample volumes ranging from 0.1 mL to 10 mL in HPLC is the injection valve method in which a loop of tubing is totally or partially filled with sample. Recent HPLC pumps have a flow‐rate setting accuracy of ±1–2% over a flow‐rate range from 0.1 mL/min to 10 mL/min and the flow stability is 0.2% or less. Quarternary low pressure gradient pumps are widely available and used, but all their hydraulic lines are seldom utilised. The idea of using one line of a common commercial HPLC quaternary low‐pressure pump for direct on‐column injection (pumping) of large sample volumes ranging from 1 mL to 100 mL was tested. This approach was evaluated during practical work on the development of an RP‐HPLC method of determination of residual atrazine and hydroxyatrazine. In lysimetric environmental experiments hydroxyatrazine was formed in situ in a soil column by hydrolysis of atrazine. The results proved the applicability of this approach not only in experiments with model mixtures of analytes at μg/L levels in solutions. Analysis of 20 mL of soil leachates and extracts of soil samples containing atrazine and hydroxyatrazine at the 10 μg/kg level (in dry soil) revealed that good figures‐of‐merit were preserved, even in the presence of a large excess of humic substances.
Method for enantiomeric purity of a quinuclidine candidate drug by capillary electrophoresis
Authors: Ramstad Tore , Johnson Rebecca L. 
Published: August 2006

AbstractA chiral procedure based on EKC was developed and validated for determination of the enantiomeric purity of PHA‐543613, a drug candidate that was under development for treatment of the cognitive deficits of Alzheimer's disease and schizophrenia. Separation of enantiomers is accomplished via differential, enantiospecific complexation with a single‐isomer, precisely sulfated beta‐CD and heptakis‐6‐sulfato‐β‐CD (HpS‐β‐CD). Both neutral and sulfated CDs were screened before selecting HpS‐β‐CD as the chiral selector. The separation is conducted in a 61 cm×50 μm uncoated fused silica capillary with 25 mM HpS‐β‐CD in pH 2.50, 25 mM lithium phosphate as the separation buffer with detection at 220 nm. Application of reverse polarity at –30 kV results in an elution time of about 12 min for PHA‐543613 and 13 min for the undesired S‐enantiomer. Quantification is versus an authentic reference S‐enantiomer as an external standard in combination with an internal standard. The procedure was validated over the range 0.1–2.0% w/w. The detection limit is 0.01–0.02%. The amount of distomer intrinsic to the drug substance is about 0.1% or less. The developed method was used to generate stability data on multiple lots: in one case for up to 3 years.
Separation and determination of epinephrine and dopamine in traditional Chinese medicines by micellar electrokinetic capillary chromatography with laser induced fluorescence detection
Authors: Dong Yuming , Chen Hongli , Chen Yonglei , Hui Yang , Chen Xingguo , Hu Zhide 
Published: August 2006

AbstractA micellar electrokinetic capillary chromatography method with laser‐induced fluorescence detection was developed for the analysis of epinephrine and dopamine after derivatization with 4‐chloro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole. The optimum derivatization conditions were: 30 mM sodium borate (pH adjusted to 8.0 with 1.0 M HCl), reaction time 30 min at 60°C. Baseline separation was achieved within 14 min with a running buffer composed of 10 mM sodium borate + 25 mM sodium dodecyl sulfate (pH adjusted to 9.5 with 0.1 M NaOH) and an applied voltage of 15 kV. Good linearity relationships (correlation coefficients: 0.9991 for epinephrine and 0.9985 for dopamine) between peak areas and concentrations of the analytes were obtained. The detection limits and quantification limits for epinephrine and dopamine were 0.0038 mg/L and 0.013 mg/L, and 0.065 mg/L and 0.020 mg/L, respectively. The method was applied to the analysis of the two compounds in two Chinese medicines with recoveries in the range of 92.6–108.7%.
Capillary electrochromatography with monolithic silica columns. V. Study of the electrochromatographic behaviors of polar compounds on monolithic silica having surface bound cyano functionalities
Authors: Zhong Hengwen , El Rassi Ziad 
Published: August 2006

AbstractIn this report, a novel polar monolithic capillary column is described for normal phase CEC (NP‐CEC) of representative polar compounds including mono‐ and oligosaccharides, peptides, and basic drugs. The polar monolithic column, which was described in detail in the preceding paper, consisted of silica‐based monolith bonded with 1H‐imidazole‐4,5‐dicarbonitrile (IDCN) and is denoted as 2CN‐OH‐Monolith. Various retention parameters for neutral polar solutes (e. g., mono‐ and oligosaccharides) and charged polar solutes (e. g., peptides and basic drugs) were evaluated over a wide‐range of elution conditions. These retention parameters yielded quantitative assessment for the polar interactions between the model solutes and the stationary phase under investigation as well as the effect of electromigration of charged solutes on their overall migration in NP‐CEC. Furthermore, this investigation demonstrated that despite the possibility of achieving isocratic separation in NP‐CEC for widely differing polar species, multistep‐gradient elution in NP‐CEC is preferred to bring about the rapid separation of a large number of polar species in a single run.
Preparation of particle‐fixed silica monoliths used in capillary electrochromatography
Authors: Qu Qishu , Tang Xiaoqing , Wang Chengyin , Yang Gongjun , Hu Xiaoya , Lu Xiao , Liu Yin , Yan Chao 
Published: August 2006

AbstractFused‐silica capillaries were packed with porous 1 μm bare silica microspheres and immobilized by potassium silicate–formamide in order to obtain columns with silica‐based monolithic packing. After curing, the particle‐fixed monolithic columns were octadecylated in situ with dimethyloctadecylchlorosilane. The columns were mechanically strong and permeable. No noticeable loss in efficiency was found after using a column continuously for 1 month. The performances of the particle‐fixed silica monolithic columns were evaluated for CEC under RP conditions. High separation efficiency (about 125 200 plates/m) was obtained by using these new types of columns.
The effect of the physical matrix on accurate measurements using fixed volume analytical techniques
Authors: Brown Richard J. C. , Edwards Peter R. 
Published: August 2006

AbstractIn order to perform high accuracy analytical measurements most analytical techniques require some form of calibration using standards of the same quantity as that being measured. The highest accuracy calibration standards are those prepared by mass (gravimetrically) as opposed to by volume (volumetrically). The use of gravimetrically prepared standards to calibrate analytical techniques that rely on fixed volume injections can cause systematic errors, even when the analytical technique does not suffer from a chemical matrix interference. The origin of these errors is explained and is demonstrated experimentally for the analysis of sulphate in synthetic seawater samples, and the measurement of the anionic content of particulate matter following extraction with water and wetting agents; where average measurement biases of +2.7 and –3.2%, respectively, were observed. Proposals are offered for methods to overcome this ‘physical matrix effect’.
Knowledge exploitation, knowledge exploration, and competency trap
Authors: Liu Weiping 
Published: August 2006

AbstractIt is no surprise that knowledge exploitation and knowledge exploration have become the consistent theme in organizational learning literature. Strategy and organization theorists have similarly observed the dynamic capabilities anchored in a firm's ability to simultaneously exploit current technologies and resources to secure efficiency benefits, and creating variation through exploratory innovation. While some studies argue that excessive exploration or excessive exploitation can lead to a competency trap, the ‘competency trap’ component actually has received less empirical scrutiny. This paper provides a study about how competency traps are formed in the process of knowledge exploration and exploitation as well as their effects on business performance.The paper includes three main sections: First, the theoretical interpretation of the ‘competency trap’ construct is broadened by investigating the formation of competency traps based on organizational learning theory; second, factors leading to the formation of different competency traps are identified; and third, the relationship between an organization's competency trap and business performance is investigated. The article ends with a discussion of implications for the organizational learning literature. Copyright © 2006 John Wiley & Sons, Ltd.
Dynamic capabilities in early‐phase entrepreneurship
Authors: Boccardelli Paolo , Magnusson Mats G. 
Published: August 2006

AbstractThe dynamic capabilities perspective has received increasing attention in the field of strategic management research. By focusing not only on the competitive advantage that is provided by a certain resource constellation, but also on the change of firms' resources over time to fit changing business environments, this perspective underlines the strategic importance of innovation. Despite the apparent interest in the dynamics of firm resources, there is still limited empirical evidence for how the strategic matching of resources and market needs is actually done, particularly in more rapidly changing environments. In order to investigate this process, an empirical study of 59 start‐ups in the Swedish mobile Internet industry was performed. A first finding from the study is that start‐ups which change market focus have a significantly higher probability to survive their first years. Furthermore, it is seen that in most cases, the change in market focus takes place without any related change in the technological resources that are used by the firm, indicating that an important factor at this stage is the flexible use of resources in searching for a suitable match between resources and market opportunities. This mode of learning and adaptation is very different from earlier proposed models focusing on the acquisition and transformation of resources. Instead, the early‐stage dynamic capabilities reveal themselves as bricolage, that is, the capacity to re‐interpret and re‐combine already existing resources and thereby improve their fit with the demands of the market environment. The results suggest that earlier proposed dynamic capabilities frameworks need to be modified, by taking into account the single entrepreneur as a source of dynamic capabilities, and by introducing the concept of resource flexibility. In terms of managerial implications, the findings underline the importance for entrepreneurs to balance the striving for distinctive capabilities that provide competitive advantage and the experimentation and improvisation needed to adapt to changes in the market. Copyright © 2006 John Wiley & Sons, Ltd.
The relationship between innovation and business performance—a comparative study between manufacturing and service firms
Authors: Prajogo Daniel I. 
Published: August 2006

AbstractThis paper explores the relationship between innovation performance (in terms of product and process) and business performance (sales growth, market share and profitability) and compares this relationship between manufacturing and service firms. This study was driven by the lack of studies on innovation in service sectors despite the importance of innovation as one of the primary sources of competitive advantage. Furthermore, as manufacturing firms and service firms are different in many respects, including innovation performance, it could be expected that manufacturing firms could pursue and emphasise different aspects of innovation than their service counterparts. Empirical data was gathered from 194 managers in Australian firms, with nearly equal proportion drawn from the manufacturing and service sectors (52% and 47% respectively). Several major findings were found through data analysis. First, there was no significant difference between manufacturing and service firms in both product and process innovation performance. The second finding, however, indicated a stronger correlation existed for manufacturing firms than for service firms between innovation and business performance, particularly in relation to process innovation. Third, it was found that process innovation shows a relatively stronger relationship with business performance than product innovation in manufacturing sectors. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and Optical Properties of Dendronized Porphyrin Polymers
Authors: Li Binsong , Fu Yaqin , Han Yang , Bo Zhishan 
Published: August 2006

AbstractSummary: A novel kind of dendronized porphyrin polymers was synthesized by Sonogashira coupling of diethynyl‐functionalized porphyrin monomers and diiodo‐functionalized macromonomers bearing Fréchet‐type dendrons. The encapsulation of red‐light‐emitting porphyrin‐containing conjugated backbones into dendronized polymers can not only reduce the aggregation of polymer backbones and the self‐quenching of their fluorescence but also endow the porphyrin polymers with good solubility. We also report the optical and electrochemical properties of the porphyrin‐containing dendronized polymers.Synthesis of a novel kind of dendronized porphyrin polymers by Sonogashira coupling of diethynyl‐functionalized porphyrin monomers and diiodo‐functionalized dendritic macromonomers.magnified imageSynthesis of a novel kind of dendronized porphyrin polymers by Sonogashira coupling of diethynyl‐functionalized porphyrin monomers and diiodo‐functionalized dendritic macromonomers.
Thermoreversible Ferrogels
Authors: Lattermann Günter , Krekhova Marina 
Published: August 2006

AbstractSummary: For the first time, thermoreversible ferrogels (FG) by physical gelation of ferrofluids have been described. Finavestan A80B paraffin oil in a concentration range of the gelator KRATON G‐1650 with Cgelator = 3–10 wt.‐%, was used to obtain stable and homogeneous FGs. TEM micrographs revealed that the magnetite particles are preferably located in the ‘free’ paraffin phase between micellar domains of the gelator. So, the magnetite nanoparticles make visible a ‘negative’ picture of the structure of the micellar domains of the gel, which is observed in the pure gel as a ‘positive’ image. The mean diameter of the polystyrene cores is $\overline d$ = 17 nm, and that of the magnetite particles is $\overline d$ = 7 nm.
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Modeling of Diffusion Limitations in Bulk RAFT Polymerization
Authors: Peklak A. David , Butté Alessandro 
Published: August 2006

AbstractSummary: The impact of diffusion limitations on RAFT polymerizations is investigated in this work. In particular, two models are compared: one accounting for diffusion limitations by using average chain lengths, the other accounting for the entire CLD. It is shown that such a description is necessary to correctly predict the kinetics of polymerization processes, as well as the evolution of average chain length and polydispersity. For properly selected study cases, differing conversion curves are obtained above 40% monomer conversion, if only average values of the CLD are considered. The same is valid for the calculation of the polydispersity, which starts differing above 80% conversion. Finally, for given conditions of diffusion limitations, it is found that an ideal polydispersity can be defined and it is shown that the polydispersity tends to this characteristic value during the entire evolution of the polymerization process.$k_{\rm t}^{{\rm CLD}} /k_{\rm t}^{{\rm DP}}$ as a function of f for various values of $\overline {DP} _n^{\rm R} /\overline {DP} _{{\rm crit}}$.magnified image$k_{\rm t}^{{\rm CLD}} /k_{\rm t}^{{\rm DP}}$ as a function of f for various values of $\overline {DP} _n^{\rm R} /\overline {DP} _{{\rm crit}}$.
Effect of Pressure on the Miscibility of Polyethylene/Poly(ethylene‐alt‐propylene) Blends
Authors: Choi Phillip , Rane Sagar S. , Mattice Wayne L. 
Published: August 2006

AbstractSummary: Effect of density, and hence pressure, on the miscibility of a 50:50 mol/mol PE/PEP blend was studied using a coarse‐grained MC simulation approach on a high‐coordination lattice, with the conformations of the coarse‐grained chains constrained by the RIS model. Interchain pair correlation functions are used to assess the miscibility of the mixtures. Miscibility increases with increasing temperature over the range −50–150 °C. It is rather insensitive to pressure at high temperatures, but at −50 °C, the blend miscibility increases with decreasing pressure. The findings are consistent with the fact that the blend is an UCST blend and that the simulation temperatures used, except −50 °C, were considerably higher than the UCST of the blend. The pressure dependence of the blend miscibility observed near −50 °C is also in agreement with the experimental observation that the blend exhibits a negative volume change of mixing. The present work demonstrates that the coarse‐grained MC approach, when it is used with periodic boundary cells of different sizes filled with the same number of chains, is capable of capturing the pressure dependence of UCST blends. In addition, such a simulation also provides us with insights about the molecular origin of the observed pressure dependence of miscibility. In the present case, the segregation of PE and PEP chains at low temperatures and high pressure simply originates from the fact that fully extended segments of PE chains tend to cluster so that their intermolecular interactions can be maximized. As the temperature increases, there is a decrease in the probability of a trans state at a CC bond in PE, and therefore the attraction between the PE chains is reduced at higher temperatures, promoting miscibility and the UCST behavior.Density (pressure) dependence of the 2nd shell pair correlation function values for a 50/50 PE/PEP blend at −50 °C.magnified imageDensity (pressure) dependence of the 2nd shell pair correlation function values for a 50/50 PE/PEP blend at −50 °C.
Directed assembly of copolymer materials on patterned substrates: Balance of simple symmetries in complex structures
Authors: Daoulas Kostas Ch. , Müller Marcus , Stoykovich Mark P. , Papakonstantopoulos Yioryos J. , de Pablo Juan J. , Nealey Paul F. , Park Sang‐Min , Solak Harun H. 
Published: August 2006

AbstractThe self‐assembly of a lamella‐forming blend of a diblock copolymer and its respective homopolymers on periodically patterned substrates is investigated by a concerted experimental and theoretical approach. The substrate pattern consists of square arrays of spots that preferentially attract one component of the blend. The mismatch between the lamellar equilibrium morphology of the copolymer material and the substrate pattern results in the formation of a bicontinuous morphology. At the substrate, a quadratically perforated lamella (QPL) assembles in perfect registry with the substrate pattern. From this, QPL necks emanate and reach the top surface of the film. The detailed structure of these cylindrical nanochannels is analyzed using Voronoi tessellation, orientation correlation functions, and the structure factor of the neck positions on the top surface. The surface morphology is dictated by the antagonism of the square symmetry of the substrate pattern and the tendency of the necks to locally pack in a hexagonal arrangement. The analogy and differences to a system of adsorbed monolayer on corrugated substrates is explored by comparing the arrangement of the necks on the film's top surface with the structure of a soft disk model on a quadratically corrugated substrate. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2589–2604, 2006
Interplay of magnetism and superconductivity
Authors: Akhavan M. 
Published: August 2006

AbstractAfter about two decades of intense research since the discovery of high‐temperature superconductivity (HTSC) in cuprates, although many aspects of the physics and chemistry of these cuprate superconductors are now well understood, the underlying pairing mechanism remains elusive. Magnetism and superconductivity are usually thought as incompatible, but in number of special materials including HTSCs these two mutually excluding mechanisms are found to coexist. The presence in a system of superconductivity and magnetism, gives rise to a large number of interesting phenomenon. This article provides perspective on recent developments and their implications for our understanding of the interplay between magnetism and superconductivity in new materials. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)