bluuebunny/crossref_metadata_2025_split huggingface dataset:
The coupling of the electrostatic potential with the transport and adsorption mechanisms in ion‐exchange chromatography systems: Theory and experiments
Authors: Liapis Athanasios I. , Grimes Brian A. 
Published: September 2005

AbstractThe coupling of the constitutive expression for the electrostatic potential as specified through Poisson's equation together with the constitutive equations for the mechanisms of convection, diffusion, electrophoretic migration, and adsorption provides the necessary set of constitutive expressions to be employed in the material balance equations of ion‐exchange chromatography systems to construct macroscopic continuum models that could be used to design and simulate the dynamic behavior of systems involving a single charged adsorbate or multiple charged adsorbates. A physically relevant and consistent macroscopic continuum model that can predict, as has been observed experimentally by UV confocal microscopy (UVCM), the presence or absence of the concentration overshoot phenomenon, based on the pH and ionic strength of the liquid solution, is discussed and expanded to describe the behavior of IEC systems involving competitive adsorption of two or more charged adsorbates. Furthermore, UVCM and confocal scanning laser microscopy (CSLM) experiments and the macroscopic continuum models that could be used to analyze their data are indicated. Results are also presented that have been obtained from molecular dynamics (MD) modeling and simulation studies (microscopic modeling and analysis) employing realistic atomistic models derived from fundamental physics, and indicate the physical mechanisms that are relevant and actively involved in the transport and adsorption of charged adsorbates in IEC systems, as well as their relative importance. The results obtained from the MD simulations show that when a charged macromolecule is adsorbed it is restrained by a strong dominant Coulombic interaction and is trapped by a hydration layer adjacent to the surface and these lead to zero lateral displacement of the adsorbed macromolecule. This finding indicates that surface diffusion could be a physically implausible mechanism in IEC systems involving charged adsorbate macromolecules. Also, the results obtained from the MD simulation studies show that the transport coefficients that characterize the mass transfer of a charged adsorbate in the liquid solution by diffusion and electrophoretic migration have magnitudes along the lateral direction that are different from those along the direction that is normal to the charged surface.
Effects of Moisture on Glass Transition and Microstructure of Glycerol‐Plasticized Soy Protein
Authors: Chen Pu , Zhang Lina , Cao Feifei 
Published: September 2005

AbstractSummary: The glass transition behavior of the glycerol‐plasticized soy protein sheets (SL series) at various relative humidity (RH) was investigated by using differential scanning calorimetry with the aluminum pan and O‐ring‐sealed stainless steel capsule, and the microstructure of these sheets was detected on small‐angle X‐ray scattering. The results revealed that there were three glass transitions (Tg1, Tg2 and Tg3), corresponding to glycerol‐rich, protein‐rich and protein‐water domains, in the protein‐glycerol‐water ternary system. The Tg1 values of the SL‐series sheets at 75% RH decreased from −49.3 to −83.8 °C with an increase of glycerol content from 10 to 50 wt.‐%, whereas Tg2 and Tg3 were almost invariable at about 60 °C and 3 °C, respectively. In addition, the Tg1, Tg2 and Tg3 values of the SL‐25 containing 25 wt.‐% glycerol at 0%, 35%, 58%, 75% and 98% RH were in the range of −12.7–−83.2 °C, 65.8–53.1 °C and 3.5–1.9 °C, respectively. The result from small‐angle X‐ray scattering indicated that the radii of gyration (Rg) of protein‐rich domain were in the range of 60–63 nm; this suggested the existence of protein macromolecules as aggregates in the stable protein‐rich and protein‐water domains. With an increase of RH, the tensile strength and Tg values of the SL‐series sheets decreased, but the elongation at break increased. In view of the results above, the moisture in ambient environment significantly influenced the Tg values and microstructures of the glycerol‐plasticized soy protein sheets, leading to the changes of the mechanical and thermal properties.Three glass transitions corresponding to glycerol‐rich, protein‐water and protein‐rich domains in glycerol‐plasticized soy protein sheets at a relative humidity of 75%.magnified imageThree glass transitions corresponding to glycerol‐rich, protein‐water and protein‐rich domains in glycerol‐plasticized soy protein sheets at a relative humidity of 75%.
Effects of Ethyl and Benzyl Groups on the Miscibility and Properties of Castor Oil‐Based Polyurethane/Starch Derivative Semi‐Interpenetrating Polymer Networks
Authors: Cao Xiaodong , Wang Yixiang , Zhang Lina 
Published: September 2005

AbstractSummary: Cornstarch derivative (ES), prepared using diethyl sulfate as an etherifying reagent, was blended with castor oil‐based polyurethane (PU) prepolymer to obtain a series of semi‐interpenetrating polymer network (semi‐IPN) materials, named as UES films. Simultaneously, other kinds of semi‐IPN (UBS2) were prepared from PU and benzyl starch (BS2) to compare the effects of the substitute groups. The differences in the miscibility and properties of the two series of materials were investigated using attenuated total reflection Fourier transform infrared spectroscopy, atomic force microscopy, dynamic mechanical thermal analysis, ultraviolet‐visible spectroscopy, water‐sensitivity and tensile testing. The experimental results revealed that UBS2 films exhibit stronger interfacial attraction and better phase mixing than the UES films, as a result of specific interactions between the PU hard segments and BS2 phenyl groups. The optical transmittance, water‐resistivity, tensile strength, and elongation at break of the UBS2 films were clearly higher than those of the UES films containing the same concentration of PU. In particular, the miscibility and properties of the UES film with 40 wt.‐% ES, were very poor, whereas the semi‐IPN films containing 70 wt.‐% benzyl starch still had a certain miscibility and good properties.1 Therefore, the phenyl groups play an important role in the improvement of the miscibility and properties of the semi‐IPN materials.Tensile strength and elongation at break of the PU/ES and PU/BS2 films with concentration of the two starch derivatives, ES and BS2.magnified imageTensile strength and elongation at break of the PU/ES and PU/BS2 films with concentration of the two starch derivatives, ES and BS2.
Monomers for Adhesive Polymers, 5
Authors: Pavlinec Juraj , Zeuner Frank , Angermann Jörg , Moszner Norbert 
Published: September 2005

AbstractSummary: 2,4,6‐Trimethylphenyl 2‐[4‐(dihydroxyphosphoryl)‐2‐oxa‐butyl]acrylate (1) was synthesized by silylation of 2,4,6‐trimethylphenyl 2‐[4‐(dimethoxyphosphoryl)‐2‐oxa‐butyl]acrylate with trimethylsilyl bromide (TMSBr) and the hydrolysis of the silyl ester resulted in the formation of polymerizable phosphonic acid 1. The structure of this new monomer was characterized by IR, 1H, 13C and 31P NMR spectroscopy. The monomer dissolves well in ethyl acetate, ethanol or water and shows a high hydrolytic stability. 1 was homopolymerized with 2,2′‐azobisisobutyronitrile (AIBN), 2,2′‐azobis‐(2‐methylpropionamidine) dihydrochloride (AMPAHC) or dibenzoyl peroxide (DBPO) as the initiators. In a tetrahydrofuran (THF) solution, the deviations from the standard reaction kinetics were comparable with those of polymerizations of the other water soluble acrylate monomers. The unusual polymerization rate‐monomer concentration dependence with monomer intensity exponent less than 1 (m = 0.5) observed in THF solutions was even more declined from 1 in the polar medium EtOH‐H2O. The DBPO was a more effective polymerization initiator than AIBN. However, the overall activation energy of 81 kJ · mol−1 showed a usual temperature‐rate dependence observed in methacrylate ester polymerizations. In addition, monomer 1 was copolymerized with methyl methacrylate (MMA), ethyl 2‐[4‐(dihydroxyphosphoryl)‐2‐oxa‐butyl]acrylate (2), and N,N′‐diethyl‐1,3‐bis(acrylamido)propane (3), respectively, using THF as the solvent and AIBN as the initiator. The copolymerization curves revealed only slight deviations from the ideal copolymer‐feed composition. The estimated copolymerization parameters indicate a ready incorporation of comonomer units into polymer chains, preferably by alteration rather than at random.2,4,6‐Trimethylphenyl 2‐[4‐(dihydroxyphosphoryl)‐2‐oxa‐butyl]acrylate.image2,4,6‐Trimethylphenyl 2‐[4‐(dihydroxyphosphoryl)‐2‐oxa‐butyl]acrylate.
Preparation of Silica‐Coated Polystyrene Hybrid Spherical Colloids
Authors: Chen Min , Zhou Shuxue , Wu Limin , Xie Songhai , Chen Ying 
Published: September 2005

AbstractSummary: A novel preparation method for stable PS/SiO2 core‐shell hybrid colloid was proposed. In this process, a positively charged PS colloid was first synthesized via surfactant‐free emulsion polymerization of styrene by using a cationic initiator, and the hydrolysis and condensation of tetraethoxysilane (TEOS) was then carried out in acidic aqueous ethanol medium in the presence of PS colloids. Silica layer was deposited onto the surface of PS particle via electrostatic interaction between positively charged PS colloids and negatively charged silica. No surface treatment and centrifugation/redispersion cycle process were needed. TEM, SEM, and zeta potential measurements indicated that silica layer was successfully coated onto the surfaces of PS colloids.PS/SiO2 hybrid core‐shell colloids with PS as core and silica layer as shell.imagePS/SiO2 hybrid core‐shell colloids with PS as core and silica layer as shell.
Synthesis, Characterization and Behavior in Aqueous Solution of Star‐Shaped Poly(acrylic acid)
Authors: Plamper Felix A. , Becker Harald , Lanzendörfer Michael , Patel Mushtaq , Wittemann Alexander , Ballauff Matthias , Müller Axel H. E. 
Published: September 2005

AbstractSummary: We report the synthesis of star‐shaped poly(acrylic acid) (PAA), with 5, 8, and 21 arms, by atom transfer radical polymerization of tert‐butyl acrylate. We employ the core‐first approach using glucose‐, saccharose‐ and cyclodextrin‐based initiators. Subsequent acidic treatment of poly(tert‐butyl acrylate) (PtBA) leads to star‐shaped poly(acrylic acid) (PAA). Alkaline cleavage of the arms enabled us to determine the initiation site efficiency. The PAA stars and arms were esterified to poly(methyl acrylate) (PMA). Molecular weight determination by means of GPC/viscosity, MALDI‐TOF MS and NMR end‐group determination showed that the initiation site efficiency is close to unity. Results from potentiometric titration of PAA arms and stars show that the apparent pKa values increase with increasing arm number, which is a direct result of increasing segment density. Osmometry measurements of aqueous solutions of the PAA stars result in osmotic coefficients between 0.05 and 0.38, indicating that most of the counterions are confined within the star. The confinement increases with arm number.Potentiometric titration curves for stars (PAA100)21, (PAA100)8, (PAA100)5, and linear PAA100.imagePotentiometric titration curves for stars (PAA100)21, (PAA100)8, (PAA100)5, and linear PAA100.
Propylene Polymerization Behavior of Fluorinated Bis(phenoxy‐imine) Ti Complexes with an MgCl2‐Based Compound (MgCl2‐Supported Ti‐Based Catalysts)
Authors: Nakayama Yasushi , Saito Junji , Bando Hideki , Fujita Terunori 
Published: September 2005

AbstractSummary: Fluorinated bis(phenoxy‐imine)Ti complexes 1–3 combined with MgCl2/i‐BunAl(OR)3−n (MgCl2‐supported catalysts) were able to polymerize propylene in a living fashion at room temperature to provide slightly to highly syndiotactic poly(propylenes) (PPs) with extremely narrow distributions of molecular weight. These represent the first examples of MAO‐ and borate‐free group 4 metal‐based living catalysts. The supported complexes 2 and 3 formed PPs with higher syndiotacticity and Tm's than the corresponding homogeneous MAO‐activation systems (e.g., 3: rr 97%, Tm 155 °C; MAO activation: rr 93%, Tm 152 °C). The measured Tm of 155 °C represents the highest known Tm for syndiotactic PPs synthesized at room temperature.Polymerization of propylene to poly(propylene) with supported Ti‐based catalysts.imagePolymerization of propylene to poly(propylene) with supported Ti‐based catalysts.
Characterization of Glycidyl Methacrylate Based Copolymers by Inverse Gas Chromatography under Finite Surface Coverage
Authors: Nastasović Aleksandra B. , Onjia Antonije E. , Milonjić Slobodan K. , Vuković Zorica M. , Jovanović Slobodan M. 
Published: September 2005

AbstractSummary: Inverse gas chromatography under finite surface coverage conditions (IGC‐FC) was used for the investigation of sorption of hexane, benzene, chloroform and tetrahydrofuran on macroporous crosslinked poly[(glycidyl methacrylate)‐co‐(ethylene glycol dimethacrylate)], poly(GMA‐co‐EGDMA), and copolymer modified with ethylene diamine, EDA, poly(GMA‐co‐EGDMA)‐en, in the temperature range 333–363 K. Two poly(GMA‐co‐EGDMA) samples with different porosity parameters were synthesized by suspension copolymerization and modified using a ring‐opening reaction of the pendant epoxy groups with EDA. The specific surface areas of the initial and modified copolymer samples were determined by the BET method from low temperature nitrogen adsorption isotherms (77 K). The adsorption isotherms determined from chromatographic peaks of adsorbates were analyzed using the BET theoretical model and used for estimation of the surface area, isosteric heat of adsorption and the adsorption energy distribution on the surface of the initial and modified copolymer samples. It was observed that the adsorbate nature and the properties of the solid surface of the initial and modified copolymer governed the uptake of adsorbate by the copolymer. The deviations observed for the Sa values obtained by the BET method from the low temperature nitrogen adsorption isotherms and hexane was attributed not only to the difference in molecule size, but also to the specific polymer‐adsorbate interactions. The isosteric heat of adsorption approached a constant value with increasing adsorbate loading. A large variation in the shapes of the qst‐α curves resulted from strong acid‐base interactions, as well as dissolution phenomena. Of the four studied adsorbates, chloroform was shown to have the greatest affinity towards the surface of the investigated polymer samples.Adsorption isotherms of hexane on sample 1 and 1a.magnified imageAdsorption isotherms of hexane on sample 1 and 1a.
Amphiphilic Block Copolymer Micelles: New Dispersant for Single Wall Carbon Nanotubes
Authors: Shin Hye‐in , Min Byung Gil , Jeong Wonyong , Park Cheolmin 
Published: September 2005

AbstractSummary: This manuscript describes a new simple method to disperse single wall carbon nanotubes (SWNTs) in various organic solvents. The method is based on using amphiphilic block copolymer micelles as a dispersant. We have found that the stabilization of SWNTs by block copolymer micelles adhering to the surface of nanotubes is much superior to that by either surfactants or high‐molecular‐weight polymers currently used. Our nondestructive method is beneficial because the amphiphilic property of the block copolymer micelles enables us to stabilize SWNTs in either polar solvents or nonpolar ones at the same time. We also demonstrate that silver nanoparticles are selectively synthesized in polar cores of micelles adsorbed on the surface of SWNTs and the subsequent heat treatment modifies the surface of SWNTs.Dispersion of silver nanoparticles on the surface of SWNTs.magnified imageDispersion of silver nanoparticles on the surface of SWNTs.
Dielectric Properties of Polyimide‐Mica Hybrid Films
Authors: Zhang Yi‐He , Dang Zhi‐Min , Xin John H. , Daoud Walid A. , Ji Jun‐Hui , Liu Yuyang , Fei Bin , Li Yuanqing , Wu Juntao , Yang Shiyong , Li Lai‐Feng 
Published: September 2005

AbstractSummary: Polyimide‐mica hybrid films were prepared via ultrasonic dispersion and in situ polymerization process from a solution of a polyimide precursor and mica in N,N‐dimethylacetamide, and their structure was characterized by FTIR and XRD techniques. The dependence of dielectric properties, such as dielectric constant and electrical breakdown strength, of the hybrid films on the content of mica was studied at room and cryogenic temperatures. The results show that the dielectric constant of PI‐mica hybrid films decreases with the increase of the mica content at temperatures from −150 to 150 °C and at frequency range from 1 kHz to 1 MHz. It was found that the cryogenic electrical breakdown strength of the PI‐mica hybrid films could meet the requirements of cryogenic insulating materials.Effect of frequency on the dielectric constant of PI‐mica hybrid films at 140 °C at the frequency from 1 kHz to 1 MHz.magnified imageEffect of frequency on the dielectric constant of PI‐mica hybrid films at 140 °C at the frequency from 1 kHz to 1 MHz.
Observations of Gelation and Vitrification of a Thermosetting Resin during the Evolution of Polymerization Shrinkage
Authors: Yu Hong , Mhaisalkar Subodh G. , Wong Ee Hua 
Published: September 2005

AbstractSummary: We report a new methodology to determine the gelation and vitrification of a thermosetting material during the polymerization process by detecting the evolution of cure shrinkage through a thermomechanical analyzer (TMA) and a differential scanning calorimeter (DSC). The gelation and vitrification determined by the evolution of cure shrinkage correspond favorably with that measured by conventional rheological techniques. The isoconversional phenomenon at gelation point was further confirmed by monitoring cure shrinkage at temperatures ranging from 90 to 110 °C. Whereas, vitrification was observed to occur at higher degrees of cure with increasing cure temperatures. Inhibited cure shrinkage was also observed in the vitrification region where the reaction transitioned from chemical to diffusion controlled.Combination of dimension change detected by DMA and heat flow detected by DSC for determining the relationship of cure shrinkage and degree of cure.magnified imageCombination of dimension change detected by DMA and heat flow detected by DSC for determining the relationship of cure shrinkage and degree of cure.
Living Polymerization of N,N‐Diphenylacrylamide with Triisobutylaluminum
Authors: Kim Yeon Cu , Jeon Manseong , Kim Sang Youl 
Published: September 2005

AbstractSummary: N,N‐Diphenylacrylamide was polymerized in a living fashion with triisobutylaluminum in THF at 0 °C. The polymerization results showed an increase of molecular weight proportional to the amount of monomer consumed and a first‐order kinetics at −78 °C. The intermediates obtained with excess initiator at −78 °C revealed that the polymerization was initiated through 1,4‐addition of hydride from a triisobutyl group in the triisobutylaluminum and then proceeded through aluminum‐oxygen bond interchange.N,N‐Diphenylacrylamide was polymerized in a living fashion with triisobutylaluminum in THF at 0 °C.magnified imageN,N‐Diphenylacrylamide was polymerized in a living fashion with triisobutylaluminum in THF at 0 °C.
A Convenient A2 + B3 Approach to Hyperbranched Poly(arylene oxindole)s
Authors: Smet Mario , Fu Yu , Zhang Xi , Schacht Etienne H. , Dehaen Wim 
Published: September 2005

AbstractSummary: We developed a facile approach to hyperbranched polymers by applying a superelectrophilic reaction within an A2 + B3 strategy. A significant reactivity difference between the intermediate and the starting material was utilized to avoid gelation in the A2 + B3 polymerization. A number of hyperbranched poly(arylene oxindole)s were achieved in a one‐step polymerization and characterized by NMR spectroscopy and gel permeation chromatography. Moreover, further modifications at the interior and exterior of the resulting polymers were explored as well.Structure of the hyperbranched polymers produced using the A2 + B3 approach.magnified imageStructure of the hyperbranched polymers produced using the A2 + B3 approach.
Enhancement of Biomolecular Recognition of DTIC Based on Functional Monodisperse Polystyrene Spheres
Authors: Zhang Renyun , Chen Haihua , Wu Chunhui , Wang Xuemei , Gu Zhongze 
Published: September 2005

AbstractSummary: Monodisperse carboxy polystyrene (PS) spheres were synthesized and utilized as an interface to increase the detection sensitivity of some biomolecules. The binding behavior of dacarbazine (DTIC), an anticancer drug, with DNA bases in the absence and presence of the PS spheres was investigated. The results indicated a remarkable effect of PS on the binding behavior of DTIC to DNA bases and significantly enhanced detection sensitivity for the relative biomolecular recognition.Electrochemical detection of DTIC on a GCE surface in the absence and presence of polystyrene spheres.magnified imageElectrochemical detection of DTIC on a GCE surface in the absence and presence of polystyrene spheres.
NMR spectroscopic characterization of the membrane affinity of polyols
Authors: Fischer Daniela , Geyer Armin 
Published: September 2005

AbstractResidual dipolar couplings (RDCs) are applied here for the analysis of weak, transient binding events between phosphatidylcholine bilayers and polyols. Large signal responses are observed even for low percentages of ‘ligand‐receptor complexes,’ making RDCs a sensitive tool for the analysis of molecular recognition events. The different degree of alignment in solution can be compared as a result of the calculation of the alignment tensor elements. By varying polarity and/or charge of the molecules under investigation, nonspecific hydrophobic effects can be excluded. Copyright © 2005 John Wiley & Sons, Ltd.
In vivo 3T spiral imaging based multi‐slice T1ρ mapping of knee cartilage in osteoarthritis
Authors: Li Xiaojuan , Han Eric T. , Ma C. Benjamin , Link Thomas M. , Newitt David C. , Majumdar Sharmila 
Published: September 2005

AbstractT1ρ describes the spin‐lattice relaxation in the rotating frame and has been proposed for detecting damage to the cartilage collagen‐proteoglycan matrix in osteoarthritis. In this study, a multi‐slice T1ρ imaging method for knee cartilage was developed using spin‐lock techniques and a spiral imaging sequence. The adverse effect of T1 regrowth during the multi‐slice acquisition was eliminated by RF cycling. Agarose phantoms with different concentrations, 10 healthy volunteers, and 9 osteoarthritis patients were scanned at 3T. T1ρ values decreased as agarose concentration increased. T1ρ values obtained with imaging methods were compared with those obtained with spectroscopic methods. T1ρ values obtained during multi‐slice acquisition were validated with those obtained in a single slice acquisition. Reproducibility was assessed using the average coefficient of variation of median T1ρ, which was 0.68% in phantoms and 4.8% in healthy volunteers. There was a significant difference (P = 0.002) in the average T1ρ within patellar and femoral cartilage between controls (45.04 ± 2.59 ms) and osteoarthritis patients (53.06 ± 4.60 ms). A significant correlation was found between T1ρ and T2; however, the difference of T2 was not significant between controls and osteoarthritis patients. The results suggest that T1ρ relaxation times may be a promising clinical tool for osteoarthritis detection and treatment monitoring. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.