bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protein adsorption in porous adsorbent particles: A multiscale modeling study on inner radial humps in the concentration profiles of adsorbed protein induced by nonuniform ligand density distributions
Authors: Riccardi Enrico , Wang Jee‐Ching , Liapis Athanasios I. 
Published: July 2009

AbstractRecently published results determined from molecular dynamics (MD) modeling and simulation studies have shown that the spatial distribution of the density of immobilized charged ligands in ion‐exchange porous adsorbent particles is most likely nonuniform and the adsorbent particles also exhibit local nonelectroneutrality. In this work, the functional forms of the nonuniform spatial distributions of the density of the immobilized ligands in four different porous adsorbent media that were determined by MD studies were employed in a macroscopic continuum model describing the transport and adsorption of a single protein in the porous particles of the four different adsorbent media. The results clearly show that inner radial humps in the concentration profiles of the adsorbed protein can occur when the spatial distribution of the density of the immobilized ligands in the porous adsorbent particles is nonuniform and also has local maxima or minima along the radial direction in the particle. The results also indicate that the rate at which the equilibrium condition is approached depends significantly on the functional form of the spatial distribution of the density of the immobilized ligands. When adsorption equilibrium has been reached, the concentration profile of the adsorbed protein exhibits the shape of the spatial distribution of the density of the immobilized ligands. The results suggest that the technique of confocal scanning laser microscopy could be used to measure the concentration profile of an adsorbed protein at equilibrium and this measurement could provide the spatial distribution of the density of the immobilized ligands, and such measurements could also be used for quality control of the adsorbent medium. The results in this work have also implications in the modeling, design, analysis, and quality control of systems involving biocatalysis. Furthermore, the results clearly indicate that it is very important to study the dynamic behavior of an adsorption system having a nonuniform spatial distribution in the density of the immobilized charged ligands and where (i) both monovalent and multivalent interactions between the single charged adsorbate and the immobilized charged ligands occur and (ii) the values of the pH and ionic strength are such that the electrophoretic effects are active.
Modeling the effect of species retention on the band broadening in perfectly ordered silica monolithic column mimics with variable external porosity and intra‐skeleton diffusivity
Authors: Detobel Frederik , Gzil Piotr , Desmet Gert 
Published: July 2009

AbstractComputational fluid dynamics simulations of the band broadening in an idealized, and highly ordered 3‐D model of silica monoliths are reported. As this high degree of order induces only a minimal eddy‐dispersion, the band broadening is very sensitive to the intra‐skeleton diffusivity and retention factor of the analytes. The simulations hence provide a maximal view on how the Cm‐ and Cs‐contributions to the band broadening depend on the intra‐skeleton diffusivity and retention factor. By comparing two model‐structures with different external porosities, some interesting qualitative insights on the effect of the through‐pore diameter are obtained as well. Because of the precisely known intra‐skeleton diffusivity, the obtained plate height data also provide an ideal test case for the general plate height expression of chromatography. Writing out this model, identifying the geometrical parameters, and determining their value using a parameter fitting algorithm, a set of parameter values can be found which allows to accurately predict the retention factor dependency of the band broadening over a very broad range of mobile phase velocities. Remaining modeling problems are the apparent intra‐skeleton diffusion dependency of the shape factor describing the intra‐skeleton mass transfer, and the absence of mathematical expressions to predict the model shape factor values.
Polymeric strong cation‐exchange monolithic column for capillary liquid chromatography of peptides and proteins
Authors: Chen Xin , Tolley H. Dennis , Lee Milton L. 
Published: July 2009

AbstractA strong cation‐exchange (SCX) monolithic stationary phase was prepared in 75 μm id capillaries by direct in situ polymerization of sulfopropyl methacrylate and polyethylene glycol diacrylate in a ternary porogen system consisting of methanol, cyclohexanol, and water. The resulting monolith exhibited good dynamic binding capacity, fast kinetic adsorption of proteins, and high permeability. The monolith had a dynamic binding capacity of ˜52 mg/mL of column volume for lysozyme and cytochrome C. The monolith was evaluated for SCX capillary LC of synthetic peptides, natural peptides, and protein standards. Fast separation of proteins was achieved in less than 4 min. The average peak capacity for peptides was 28 using a relatively steep gradient when hydrophobic interactions were suppressed with 40% acetonitrile.
Synthesis and Characterization of Hyperbranched Poly(arylene ether)s from a New Activated Trifluoro B3 Monomer Adopting an A2 + B3 Approach
Authors: Banerjee Susanta , Komber Hartmut , Häußler Liane , Voit Brigitte 
Published: July 2009

AbstractA new trifluoromethyl‐activated trifluoro monomer was successfully prepared by Pd‐initiated coupling of 1,3,5‐tribromobenzene with 4‐fluoro‐3‐trifluoromethylphenylboronic acid. 1,3,5‐Tris(4‐fluoro‐3‐trifluoromethylphenyl)benzene (B3) leads to several hyperbranched poly(arylene ether)s when reacted with three different bisphenols (A2) in different molar ratios. The 1.5:1 molar product of A2/B3 showed very high molecular weight without significant gelation. The products have been well characterized by GPC, DSC, TGA, FTIR, and NMR techniques. The 19F NMR signals were used to calculate the degree of branching. The 1.5:1 molar products have excellent thermal stability and higher glass transition temperatures than their linear analogs.magnified image
Heterophase Polymerization as Synthetic Tool in Polymer Chemistry for Making Nanocomposites
Authors: Tauer Klaus , Weber Nancy , Nozari Samira , Padtberg Klaus , Sigel Reinhard , Stark Arne , Völkel Antje 
Published: July 2009

AbstractSummary: The paper considers various possibilities to produce inorganic – polymeric nanocomposites via aqueous heterophase polymerization. Special emphasis is placed on strategies to synthesize nanocomposite particles via joint nucleation or joint polymerization. The former strategy is used to make composite particles with CaCO3 as inorganic component. The strategy of joint polymerization takes advantage from the condition that aqueous heterophase polymerization is a convenient possibility to synthesize amphiphilic block copolymers. This method relies on the fact that polymeric radicals can survive in isolated latex particles that are stabilized by hydrophilic blocks. This strategy can be successfully applied to produce silica‐containing block copolymer particles in a one‐step procedure.
Synthesis of Poly(vinyl acetate)‐block‐poly(dimethylsiloxane)‐block‐poly(vinyl acetate) Copolymers by Iodine Transfer Photopolymerization in Miniemulsion
Authors: Tonnar Jeff , Pouget Emmanuel , Lacroix‐Desmazes Patrick , Boutevin Bernard 
Published: July 2009

AbstractSummary: Iodine transfer polymerization of vinyl acetate in aqueous miniemulsion, initiated by UV radiation in the presence of an α,ω‐diiodo‐poly(dimethylsiloxane) macrophotoiniferter has been performed. The formation of a triblock copolymer latex PVAc‐b‐PDMS‐b‐PVAc has been evidenced by 1H‐NMR and size exclusion chromatography. The size of the PDMS and PVAc blocks were modulated thus opening the way to a wide range of copolymers with different properties. A detailed study of the reaction mechanism showed the importance of the aqueous dispersed medium to achieve a controlled polymerization.
Emulsification for Latex Production Using Static Mixers
Authors: El‐Jaby Ula , Farzi Ghomali , Bourgeat‐Lami Elodie , Cunningham Michael , McKenna Timothy F.L. 
Published: July 2009

AbstractSummary: Evolution of droplets generated by static mixers have been investigated in terms of surfactant concentration, flow rate through the pump, monomer hydrophobicity and the type of static mixer. Operating at faster pump flow rates and using the PAC static mixers generated smaller miniemulsion droplets. Similar effects were observed at higher surfactant concentrations (3.0 vs. 1.0 g/L) and using monomers of increasing hydrophilicity (MMA vs. St). When comparing the efficiency of PAC static mixers to SMX mixing elements it was found that SMX was capable of generating droplets approximately 100 nm smaller at similar pump flow rates in the same time period. Based on these promising results, the SMX mixers were further evaluated based on surfactant concentration. The miniemulsion droplets were polymerized and their distribution was evaluated.
Latex Film Formation in the Environmental Scanning Electron Microscope
Authors: Dragnevski Kalin , Donald Athene , Taylor Phil , Murray Martin , Davies Simon , Bone Elizabeth 
Published: July 2009

AbstractSummary: Environmental scanning electron microscopy (ESEM) was used to study the film formation mechanisms and extent of coalescence of three acrylic latex compositions with different glass transition temperatures (Tg), here defined as standard‐low Tg, standard‐high Tg (both carboxymethyl cellulose‐ stabilised) and novel (stabilised with a novel polysaccharide derived from agricultural waste). The ESEM analysis revealed that the microstructure of the standard – low‐Tg system consisted of individual particles in dispersion and upon evaporation a continuous film formed, whereas in the case of the standard ‐ high Tg latex particle deformation was not observed, but particle aggregation resulted in the formation of crystal‐like structures that have formed via the formation of stacking faults. However, in the case of the novel system the microstructure consisted of individual particles and clusters and during evaporation a discontinuous film formed with voids present within its structure and some of the clusters accumulating on the surface of the specimens.
Polarity and Temperature‐Dependent Properties of Poly(N‐isopropylacrylamide) and Poly(N,N‐diethylacryl‐amide) Hydrogels Studied by Liquid Chromatography
Authors: Hradil Jiří , Macková Hana , Horák Daniel 
Published: July 2009

AbstractSummary: Superporous N‐isopropylacrylamide (NIPAAm) and N,N‐diethylacrylamide (DEAAm) copolymers with N,N'‐methylenebisacrylamide (MBAAm) were prepared by radical polymerization with the aim to determine their temperature‐dependent changes in polarity by liquid chromatography. Superpores were formed by the salt‐leaching technique using NaCl as a porogen. Porosities of the hydrogels characterized by water regain and mercury porosimetry, ranging from 81 to 91%, were proportional to the volume of NaCl porogen in the feed. The retention volumes of several phenols decreased with increasing temperature as polarity of the hydrogels decreased. A jump change in solute retention volume was observed at ca. 32 °C in PNIPAAm and at ca. 35 °C in PDEAAm indicating a change in the mechanism of interaction. The Gibbs energy changes ΔGCH2 were rather low, increasing in the order phenol < benzyl alcohol < ethanol < butan‐1‐ol. In contrast to the solutes, retention volumes of bovine serum albumin and dextrans were higher at higher temperature confirming thus hydrophobic interactions of the compounds with the studied hydrogels.
Critical Exponents of Thermal Phase Transitions ofκ‐Carrageenan in Various Salt Solutions
Authors: Tarı Özlem , Pekcan Önder 
Published: July 2009

AbstractSummary: The steady state fluorescence (SSF) technique was employed to study the phase transitions of κ‐carrageenan in NaCl and KCl solutions. Pyranine was used as a fluorescence probe for monitoring these transitions. Scattered light, Isc, and fluorescence intensity, I, was monitored against temperature to determine transition temperatures and exponents. It was observed that transition temperatures are strongly correlated with the NaCl and KCl contents. The weight‐average degree of polymerization, DPw and gel fraction G, exponents (γ and β) were measured and found to be in accord with the classical Flory‐Stockmayer model.
Surfactant and Electrolyte Effects on Latex Depletion Flocculation by Thickeners
Authors: Kostansek E. C. 
Published: July 2009

AbstractSummary: Polymer thickeners can induce good dispersion, bridging, or depletion flocculation of latexes depending on the polymer structure and concentration. Unlike non‐associative polymers, associative polymers have the ability to create a good latex dispersion. However, when the associative interactions are destroyed, depletion flocculation of the latex can result. This happens when an excess of ionic surfactant is added to the system. In addition, the surfactant may associate with the thickener backbone, thus modifying the molecular volume of the polymer thickener. This paper explores the effect of anionic surfactant and electrolyte on the molecular volume of both associative and non‐associative thickeners. Both HEUR and HASE structures are included. For HEUR thickeners, formation of a pseudo‐polyelectrolyte through the association of anionic surfactant with the polyethylene oxide backbone is confirmed. Further, the ability of the thickener to depletion flocculate latexes as a function of surfactant and electrolyte is explored. Experimental critical flocculation concentrations (CFC) are compared to values expected based on molecular volume and potential energy calculations. A good correlation is found between molecular volume and CFC for a wide range of thickener compositions.
Compact CPW‐fed tri‐band monopole antenna for PCS and 2.4/5GHz WLAN applications
Authors: Chen Lei , Shi Xiao‐wei , Zhang Tian‐ling , Song Yue 
Published: July 2009

AbstractA compact tri‐band monopole antenna with coplanar waveguide (CPW)‐fed structure is presented for applications in PCS and 2.4/5 GHz WLAN systems. By using a spiral strip and a meandered strip closed to an inverted‐L ground strip, the proposed antenna with a compact size of 30 × 30 × 1.6 mm3 including the ground can not only meet the impedance bandwidth requirements for PCS band (1.85–1.99 GHz) and WLAN bands (2.4–2.484 GHz and 5.15–5.825 GHz), but also can provides good radiation characteristics and antenna gains for the operating bands, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2495–2498, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24593
A novel K‐shaped dual‐band antenna with a shorting pin for WLAN communications
Authors: Choi Sun‐Ho , Lee Hwa‐Choon , Kwak Kyung‐Sup 
Published: July 2009

AbstractIn this article, a novel K‐shaped dual‐band antenna with a shorting pin for 5.2/5.8 GHz wireless local area network (WLAN) operations is designed and fabricated. To obtain sufficient bandwidth when return loss (RL) < −10 dB, a shorting pin is inserted in the patch and a coaxial probe source is used. The measured result of the fabricated antenna has 221 MHz bandwidth from 5.145 to 5.366 GHz and a 187 MHz bandwidth from 5.695 to 5.882 GHz (RL < −10 dB) with the gain ranging from 3.66 to 4.58 dBi. A good radiation pattern is achieved for the WLAN band (5.150–5.350 GHz and 5.725–5.825 GHz) range. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2442–2444, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24609
Study of a uniplanar printed internal WWAN laptop computer antenna including user's hand effects
Authors: Lee Cheng‐Tse , Wong Kin‐Lu 
Published: July 2009

AbstractA uniplanar monopole antenna to be printed on a thin (0.4 mm) and small‐size FR4 substrate and capable of GSM850/900/1800/1900/UMTS penta‐band WWAN operation for thin‐profile laptop computer application is presented. The antenna is formed by a direct‐fed shorter radiating strip for upper‐band operation at about 1900 MHz and a coupled‐fed longer radiating strip which is also short‐circuited to the antenna ground for lower‐band operation at about 900 MHz. Note that the two radiating strips are fed using different excitation mechanisms. With the coupling excitation and short‐circuiting, which functions as an internal printed matching circuitry, the longer radiating strip can provide a wide dual‐resonant lower band at around 900 MHz for GSM850/900 operation. A wide upper band can also be generated at about 1900 MHz for the antenna to cover GSM1800/1900/UMTS operation. The antenna is studied in the article, and the user's hand effects on the performances of the antenna are analyzed. The obtained results are useful for the antenna employed in the laptop computer with a touch panel. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2341–2346, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24614
Attenuation fitting functions
Authors: Fugihara Meire C. , Pinto Armando Nolasco 
Published: July 2009

AbstractThe usual exponential approximation for ultraviolet UV absorption in optical fibers could not fit the attenuation coefficient over a broad spectral range. As the UV absorption spectrum is a result of electronic transitions, we propose a Lorentzian function to model this contribution. Experimental results show a good agreement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2294–2296, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24617
All‐optical clock division with simultaneous wavelength conversion using an optically injected Fabry‐Perot laser diode
Authors: Lv Yu‐Xiang , Sun Shuai , Yang Xing 
Published: July 2009

AbstractThe authors propose and experimentally demonstrate a novel technique that uses a single Fabry‐Perot laser diode (FP‐LD) to perform simultaneous all‐optical clock division and wavelength conversion. By utilizing the nonlinear dynamical period‐one oscillation and the cross‐gain modulation effect of the light injection semiconductor laser, we achieve the all optical clock frequency division of 12.36 GHz to 6.18 GHz with simultaneous wavelength conversion from 1550.24 nm to 1545.91 nm. The phase noise of the extracted optical clock is less than −105 dBc/Hz. It was empirically found that the best clock division and wavelength conversion occurred when the injected signal power was approximately 2–2.5 times as the injected probe light power, and the range of optimum wavelength detuning was about from −0.01 nm to 0.06 nm. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2428–2431, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24626
A highly efficient class‐F power amplifier for wideband linear power amplifier applications
Authors: Kim Jangheon , Moon Junghwan , Hong Sungchul , Kim Bumman 
Published: July 2009

AbstractIn this letter, a highly efficient class‐F power amplifier (PA) is developed as a new main block of the wideband base‐station linear power amplifier. The class‐F PA is implemented using Eudyna EGN010MK GaN HEMT with a 10‐W peak envelop power. The nonlinearity and memory effects of class‐F PA are explored to apply the wideband application. The maximum power‐added efficiency of the implemented PA is 68% at a saturated output power of 40 dBm for the 2.14‐GHz CW signal. The PA delivers a good efficiency of 35% at an average output power of 32.3 dBm for wide‐band code division multiple access 3FA signal with 15‐MHz bandwidth, and the linearity can be improved to about −48 dBc using the digital feedback predistortion linearization technique. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2323–2326, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24631
Tunable medium power multiwavelength fiber laser
Authors: Dastmalchi Mansour , Das Gautam 
Published: July 2009

AbstractThe authors report a medium power spacing tunable multiwavelength fiber laser operating at room temperature. A double‐clad erbium‐ytterbium co‐doped fiber was used to produce high output power. An unpumped polarization‐maintaining fiber and a Lyot‐Sagnac loop filter with multiple segments of polarization‐maintaining fibers were used as a saturable absorber to stabilize the laser wavelengths and tunable filter to tune the separation between lasing wavelengths, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2517–2519, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24648
Solution of very large integral‐equation problems with single‐level FMM
Authors: Landesa L. , Taboada J. M. , Obelleiro F. , Rodríguez J. L. , Mouriño C. , Gómez A. 
Published: July 2009

AbstractWe present a massively parallel version of the single‐level fast multipole method, which allows the efficient use of hundreds of processors. A very large problem with more than 32 millions of unknowns is solved in 512 processors, which becomes a new record in scalability for this kind of problems. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2451–2453, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24651
Circularly polarized ceramics dielectric resonator antenna excited by Y‐shaped microstrip
Authors: Li Li‐Xian , Zhong Shun‐Shi , Xu Sai‐Qing , Chen Min‐Hua 
Published: July 2009

AbstractA circularly polarized ceramics dielectric resonator antenna fed by a Y‐shaped microstrip is proposed and analyzed. The CP design is achieved by simply adjusting the lengths and widths of two quadrate shorted stubs. The antenna is compact in structure, whose radius is only 4.5 mm. The reflection, polarization, and radiation characteristics of the antenna are studied. For the proposed antenna, with relative dielectric constant of resonator εr1 = 38, a measured impedance bandwidth of 6.8%, a measured minimum axial ration of 0.8 dB, and a wide beamwidth of 164°are achieved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2416–2418, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24653
A slot‐coupling coplanar waveguide‐fed fan‐shaped antenna embedded in semicircle aperture
Authors: Li Qin‐Yi , Zhao Gang , Jiao Yong‐Chang 
Published: July 2009

AbstractA novel design of a fan‐shaped antenna embedded in semicircle aperture is proposed and experimentally studied in this article. The proposed antenna is fed by a tapered coplanar waveguide (CPW) and has an ultrawide band owing to the coupling between the fan‐shaped radiation unit and the ground. From experimental results, the measured impedance bandwidth of the antenna, determined by −10 dB return loss, can reach an operating bandwidth of 23.36 GHz (1.64–25 GHz), more than 175% with the center frequency operating at about 13.32 GHz. Good radiation patterns and gains covering the operating band have been observed. Details of the antenna design and experimental results are discussed in this article. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2385–2387, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24655