bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perfluorinated alginate for cellular encapsulation
Authors: Gattás‐Asfura Kerim M. , Fraker Christopher A. , Stabler Cherie L. 
Published: April 2012

AbstractMolecules of pentadecafluorooctanoyl chloride (PFC) were grafted onto alginate (Alg) using a linear poly(ethylene glycol) linker and amide bonds. The resulting Alg‐PFC material was characterized by proton nuclear magnetic resonance and infrared spectroscopies. The degree of PFC functionalization significantly influenced the physical and chemical properties of Alg‐PFC, particularly when the resulting polymer was ionically crosslinked into hydrogels. Alg‐PFC hydrogel beads fabricated via Ba2+ crosslinking were found to match the permeability properties of control alginate beads, except upon swelling over time in culture media. When used to encapsulate MIN6 cells, a beta cell line, Alg‐PFC beads demonstrated enhanced cell proliferation over alginate control beads. These results indicate that Alg‐PFC hydrogels retain some of the PFC's biological‐relevant benefits, such as enhancement of mass transport and bioinertness, to enhance cellular viability within alginate three‐dimensional hydrogel environments. We envision these functionalized hydrogels to be particularly useful in the encapsulation of cells with a high metabolic demand, such as pancreatic islets. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A 2012.
Micropatterned antibody‐terminated nanocomposites (MANs) fabricated using layer‐by‐layer lift‐off (LBL‐LO) technique
Authors: Shaik Jameel , Mills David K. 
Published: April 2012

AbstractPatterned functional biomolecular surfaces have been created using a wide range of fabrication methods for applications in cell‐based studies, with the most common methods based on photolithography or soft lithography. In this study, a simple fabrication method combining photolithography, layer‐by‐layer (LbL) self‐assembly, and photoresist lift‐off (LO) was used to create spatially defined nanocomposite micropatterns of antibodies on polyelectrolyte‐protein multilayer beds. The two components of the micropatterned surfaces consisted of an anti‐CD44 rat monoclonal antibody atop a vitronectin‐coated multilayer film and an anti‐rat osteopontin (MPIIIB101) anitibody atop a fibronectin‐coated multilayer film. The micropatterned antibody‐terminated nanocomposites (MANs) were characterized using bright field microscopy, surface profilometry, and atomic force microscopy. The results demonstrate that LbL‐LO method can be successfully used to create patterns of proteins and antibodies in precise spatial arrangements. The MAN surfaces can be utilized in many bionanotechnology applications, including patterned cell cocultures or tricultures, cytotoxicity testing, drug screening, and biosensing. In addition, the general fabrication approach used in this study is applicable to other antibodies and other ligands. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2012.
Preparation and Characterization of Epoxy/Inorganic Anti‐electrostatic Nanocomposites Using Submicrometer Al(OH)3 and Colloid Al2O3
Authors: Chen Jung‐Hui , Liu Shao‐Te , Cheng Pao‐Swu 
Published: April 2012

AbstractNew organic‐inorganic hybrid materials and their anti‐electrostatic hybrid membranes are prepared via sol‐gel process. The polycondensation of epoxy oligomers and AEAPS/Al2O3 complexes which are organically surface modified submicrometer aluminum trihydroxide inorganic fillers with an active aminoterminal silane coupling agent, N‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane (AEAPS), are performed. AEAPS enhances the interfacial interactions between the inorganic fillers and epoxy polymers. Meanwhile, this coupling agent maintains well dispersion of fillers in these composites. To improve the mechanical strength and thermal stability, pyromellitic dianhydride (PMDA) is used as curing agent. These hybrid films prepared from this method have excellent physical properties, such as UV‐shielding, high transmission in visible resign (> 85%), high hardness (7∼8H) , high adhesive force (7∼8) and low relative surface resistance (9.71 × 1011∼1.26 × 1010 Ω/cm2) with anti‐electrostatic characters. For thermal resistance, the best Td value of epoxy/PMDA/AEAPS/Al2O3 is 378.6 °C which is 85.4 °C higher than that of neat epoxy resin. Physical properties of these materials are almost the same as those of the nanocomposites prepared from expensive colloid Al2O3. Evidences from TEM micrograph show that the inorganic additives are dispersed evenly in organic matrix with nanometer scale.
Design of laminated piezocomposite shell transducers with arbitrary fiber orientation using topology optimization approach
Authors: Kiyono C.Y. , Silva E.C.N. , Reddy J.N. 
Published: April 2012

SUMMARYSensor and actuator based on laminated piezocomposite shells have shown increasing demand in the field of smart structures. The distribution of piezoelectric material within material layers affects the performance of these structures; therefore, its amount, shape, size, placement, and polarization should be simultaneously considered in an optimization problem. In addition, previous works suggest the concept of laminated piezocomposite structure that includes fiber‐reinforced composite layer can increase the performance of these piezoelectric transducers; however, the design optimization of these devices has not been fully explored yet. Thus, this work aims the development of a methodology using topology optimization techniques for static design of laminated piezocomposite shell structures by considering the optimization of piezoelectric material and polarization distributions together with the optimization of the fiber angle of the composite orthotropic layers, which is free to assume different values along the same composite layer. The finite element model is based on the laminated piezoelectric shell theory, using the degenerate three‐dimensional solid approach and first‐order shell theory kinematics that accounts for the transverse shear deformation and rotary inertia effects. The topology optimization formulation is implemented by combining the piezoelectric material with penalization and polarization model and the discrete material optimization, where the design variables describe the amount of piezoelectric material and polarization sign at each finite element, with the fiber angles, respectively. Three different objective functions are formulated for the design of actuators, sensors, and energy harvesters. Results of laminated piezocomposite shell transducers are presented to illustrate the method. Copyright © 2012 John Wiley & Sons, Ltd.
An algorithm to identify medical practices common to both the General Practice Research Database and The Health Improvement Network database
Authors: Cai Bing , Xu Weifeng , Bortnichak Edward , Watson Douglas J. 
Published: April 2012

ABSTRACTPurposeTo identify practices common to both the General Practice Research Database and The Health Improvement Network database for purposes of combining the databases for analysis without duplicate records.MethodsWe developed two independent algorithms to identify practices common to the two databases. The first used the total number of patients in the therapy and clinical data sets and the total number of etoricoxib and celecoxib users each year during the study period. The second used the total number of patients stratified by gender and four different categories of birth year. Further checking of potential matched practice pairs identified by the two algorithms was performed by comparing the patient‐level medical records by birth year, dates of clinical visits, and diagnosis codes.ResultsThree hundred twelve potential matched pairs of practices were found by both algorithms. Fifteen additional potential pairs were matched by only one algorithm: 13 by algorithm 1 (A1) only and 2 by algorithm 2 (A2) only. The examination of the patient‐level visit dates and diagnosis codes for the matches revealed that all of the 327 potential pairs of duplicate practices were in fact the same practice in the two databases.ConclusionsThe two algorithms successfully found the practices common to the two different databases without de‐identifying the practices. The identification of the common practices allows for combining the two databases without duplicate records to create a larger data set for analysis, with 168 more practices than when using the General Practice Research Database alone, or with 268 more practices than when using The Health Improvement Network alone. Copyright © 2012 John Wiley & Sons, Ltd.
2,3‐bis(5‐Hexylthiophen‐2‐yl)‐6,7‐bis(octyloxy)‐5,8‐di(thiophen‐2‐yl) quinoxaline: A good construction block with adjustable role in the donor‐π‐acceptor system for bulk‐heterojunction solar cells
Authors: Li Shuang , He Zhicai , Yu Jian , Chen Su'an , Zhong Aoshu , Wu Hongbin , Zhong Cheng , Qin Jingui , Li Zhen 
Published: April 2012

AbstractThree 2,3‐bis(5‐hexylthiophen‐2‐yl)‐6,7‐bis(octyloxy)‐5,8‐di(thiophen‐2‐yl)‐quinoxaline (BTTQ)‐based conjugated polymers, namely, PF‐BTTQ (P1), PP‐BTTQ (P2), and PDCP‐BTTQ (P3), were successfully synthesized for efficient polymer solar cells (PSCs) with electron‐rich units of fluorene and dialkoxybenzene and electron‐deficient unit dicyanobenzene, respectively. All the polymers exhibited good solubility in common organic solvents and good thermal stability. Their deep‐lying HOMO energy levels enabled them good stability in the air and the relatively low HOMO energy level assured a higher open circuit potential when used in PSCs. Bulk‐heterojunction solar cells were fabricated using these copolymers blended with a fullerene derivative as an acceptor. All of them exhibited promising performance, and the best device performance with power conversion efficiency up to 3.30% was achieved under one sun of AM 1.5 solar simulator illumination (100 mW/cm2). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
High density cationic polymer brushes from combined “click chemistry” and RAFT‐mediated polymerization
Authors: Demirci Serkan , Caykara Tuncer 
Published: April 2012

AbstractA simple method for preparing cationic poly[(ar‐vinylbenzyl)trimethylammonium chloride)] [poly(VBTAC)] brushes was used by combined technology of “click chemistry” and reversible addition‐fragmentation chain transfer (RAFT) polymerization. Initially, silicon surfaces were modified with RAFT chain transfer agent by using a click reaction involving an azide‐modified silicon wafer and alkyne‐terminated 4‐cyanopentanoic acid dithiobenzoate (CPAD). A series of poly(VBTAC) brushes on silicon surface with different molecular weights, thicknesses, and grafting densities were then synthesized by RAFT‐mediated polymerization from the surface immobilized CPAD. The immobilization of CPAD on the silicon wafer and the subsequent polymer formation were characterized by X‐ray photoelectron spectroscopy, water contact angle measurements, grazing angle‐Fourier transform infrared spectroscopy, atomic force microscopy, and ellipsometry analysis. The addition of free CPAD was required for the formation of well‐defined polymer brushes, which subsequently resulted in the presence of free polymer chains in solution. The free polymer chains were isolated and used to estimate the molecular weights and polydispersity index of chains attached to the surface. In addition, by varying the polymerization time, we were able to obtain poly(VBTAC) brushes with grafting density up to 0.78 chains/nm2 with homogeneous distributions of apparent needle‐like structures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Irreversible helix rearrangement from Cis‐transoid to Cis‐cisoid in poly(p‐n‐hexyloxyphenylacetylene) induced by heat‐treatment in solid phase
Authors: Motoshige Asahi , Mawatari Yasuteru , Yoshida Yoshiaki , Seki Chigusa , Matsuyama Haruo , Tabata Masayoshi 
Published: April 2012

AbstractPolymerization of p‐n‐hexyloxyphenylacetylene (pHPA) by using a [Rh(norbornadine)Cl]2‐triethylamine catalyst was carried out at room temperature to afford stereoregular helical poly(p‐n‐hexyloxyphenylacetylene)s (PpHPAs). When ethanol and n‐hexane were used as polymerization solvents, a bright yellow PpHPAs, poly(Y) with Mn = 8.5 × 104 and its purple red polymer, poly(R) with Mn = 5.3 × 104 were obtained in 95% yields and 84% yields, respectively. Diffuse reflective UV–vis spectra of poly(Y) and poly(R) in solid phase showed different broad absorption peaks at 445 and 575 nm, respectively. X‐Ray diffraction patterns of poly(Y) and poly(R) showed typical columnar structures assignable to cis‐transoid and cis‐cisoid structures, respectively, which were also supported by molecule mechanics calculation. Poly(Y) was irreversibly transformed to a reddish‐black polymer, poly(Y‐B), which columnar diameter was nearly the same as that of poly(R). Further, poly(Y) showed an exothermic peak in the differential scanning calorimetry trace at 80 °C for 1 h in N2 gas. Thus, these findings suggest a thermally irreversible rearrangement from an unstable cis‐transoid form, poly(Y) with a stretched cis‐transoid helix to a stable cis‐cisoid form, poly(R), with a contracted cis‐cisoid helix in the solid phase to give poly(Y→B) with the cis‐cisoid form. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis of gradient copolymers with simultaneously tailor‐made chain composition distribution and glass transition temperature by semibatch ATRP: From modeling to application
Authors: Zhou Yin‐Ning , Li Jin‐Jin , Luo Zheng‐Hong 
Published: April 2012

AbstractRecent studies have demonstrated that gradient copolymers exhibit unique thermal properties. Although these properties can be determined by copolymer composition, other factors such as chain and sequence lengths and their distributions can also influence them. Accordingly, the synthesis of gradient copolymers requires simultaneously tailor‐made chain structure and thermal properties. In this work, we carried out a systematic study on the preparation of poly(methyl methacrylate‐grad‐2‐hydroxyethyl methacrylate) [poly(MMA‐grad‐HEMA)] with synchronously tailor‐made chain composition distribution and glass transition temperature (Tg) through semibatch atom transfer radical polymerization. First, a comprehensive model for simultaneously predicting gradient copolymer microstructure and Tg was presented using the concept of pseudo‐kinetic rate coefficients and Johnston equation. The model was validated by comparing simulation results with the classical reference data. Furthermore, the model was used to guide the experimental synthesis of the poly(MMA‐grad‐HEMA) gradient copolymers potentially as excellent damping material. The thermal properties of these gradient copolymer samples were evaluated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis, reactivity, and optoelectronic properties of poly(3‐alkenylthiophene) diblock copolymers
Authors: Bhatt Mahesh P. , Huynh Martin K. , Sista Prakash , Nguyen Hien Q. , Stefan Mihaela C. 
Published: April 2012

AbstractPoly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene) and poly(3‐hexylthiophene)‐b‐poly(3‐undecenylthiophene) diblock copolymers have been synthesized by McCullough method. X‐ray diffraction analysis of the diblock copolymers displayed all the reflection peaks specific to regioregular poly(3‐hexylthiophene), indicating that the presence of poly(3‐alkenylthiophene) block does not affect the packing of the polymer in the solid state. The synthesized diblock copolymers were subjected to hydroboration/oxidation and hydrosilation to demonstrate the reactivity of the alkenyl substituents. Furthermore, poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene) was used as a chain transfer agent for the ruthenium‐catalyzed ring‐opening metathesis polymerization of cyclooctene to generate a polycyclooctene graft copolymer, which was hydrogenated to give poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene‐g‐polyethylene). The opto‐electronic properties and the morphology of the synthesized polymers have been investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Controlling the formation of long‐subchain hyperbranched polystyrene from seesaw‐type AB2 macromonomers: Solvent polarity and solubility
Authors: He Chen , He Wei‐Dong , Li Lian‐Wei , Jiang Wen‐Xing , Tao Jing , Yang Jing , Chen Long , Ge Xue‐Song , Chen Sheng‐Qi 
Published: April 2012

AbstractThrough atom transfer radical polymerization of styrene with 1,3‐dibromomethyl‐5‐propargyloxy‐benzene as initiator followed by the conversion of bromine end‐groups into azide end‐groups, well‐defined seesaw‐type polystyrene (PSt) macromonomers with two molecular weights (Mn = 8.0 and 28.0 k) were obtained. Thus, a series of long‐subchain hyperbranched (lsc‐hp) PSt with high overall molar masses and regular subchain lengths were obtained via copper‐catalyzed azide–alkyne cycloaddition click chemistry performed in THF and DMF, respectively. The polycondensation of seesaw‐type macromonomers was monitored by gel permeation chromatography. Because DMF is the reaction medium with higher polarity, click reaction proceeds more easily in DMF. Therefore, the growth of lsc‐hp PSt in DMF has faster rate than that in THF for the shorter seesaw‐type macromonomer (Seesaw‐8k). However, THF is the solvent with better solubility to PSt and leads to looser conformation of PSt chains. Thus, for the longer seesaw macromonomer (Seesaw‐28k), lsc‐hp PSt in THF has higher overall molar mass. As well, the self‐cyclization of seesaw‐type macromonomers also depends on both solvent and molar mass of macromonomer. The self‐cyclization degrees of Seesaw‐8k in DMF and THF are almost the same while that of Seesaw‐28k macromonomer is obviously lower in THF. The experimental results suggest a physical consideration to control the growth of hyperbranched polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Effects of prepolymer structure in holographic polymer dispersed liquid crystal
Authors: Jang Min Woo , Yoon Tae‐Hoon , Kim Byung Kyu 
Published: April 2012

AbstractThree different types of polyols—poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), and poly(tetramethylene glycol)—with different molecular weights (Mn) were incorporated into the prepolymer structure, and the effects were examined with regard to the morphology and performance of holographic polymer dispersed liquid crystal. Among them, PEG showing the lowest glass transition temperature (Tg) exhibited the lowest threshold voltage (Vth), lowest operating voltage (Vop), and lowest diffraction efficiency with slow grating formation owing to its high viscosity of prepolymer mixture. The Tg decreased with increasing Mn because of the decreased crosslink density and hydrogen bonding, which reduced the anchoring strength, Vth and Vop. PPG400 gave Vth and Vop of approximately 7 and 24 V, respectively, with a contrast ratio of approximately 12. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Computational identification of self‐inhibitory peptides from envelope proteins
Authors: Xu Yongtao , Rahman Noorsaadah A.B.D. , Othman Rozana , Hu Peijun , Huang Meilan 
Published: April 2012

AbstractFusion process is known to be the initial step of viral infection and hence targeting the entry process is a promising strategy to design antiviral therapy. The self‐inhibitory peptides derived from the enveloped (E) proteins function to inhibit the protein–protein interactions in the membrane fusion step mediated by the viral E protein. Thus, they have the potential to be developed into effective antiviral therapy. Herein, we have developed a Monte Carlo‐based computational method with the aim to identify and optimize potential peptide hits from the E proteins. The stability of the peptides, which indicates their potential to bind in situ to the E proteins, was evaluated by two different scoring functions, dipolar distance‐scaled, finite, ideal‐gas reference state and residue‐specific all‐atom probability discriminatory function. The method was applied to α‐helical Class I HIV‐1 gp41, β‐sheet Class II Dengue virus (DENV) type 2 E proteins, as well as Class III Herpes Simplex virus‐1 (HSV‐1) glycoprotein, a E protein with a mixture of α‐helix and β‐sheet structural fold. The peptide hits identified are in line with the druggable regions where the self‐inhibitory peptide inhibitors for the three classes of viral fusion proteins were derived. Several novel peptides were identified from either the hydrophobic regions or the functionally important regions on Class II DENV‐2 E protein and Class III HSV‐1 gB. They have potential to disrupt the protein–protein interaction in the fusion process and may serve as starting points for the development of novel inhibitors for viral E proteins. Proteins 2012; © 2012 Wiley Periodicals, Inc.
A General Strategy for Self‐Assembly of Nanosized Building Blocks on Liquid/Liquid Interfaces
Authors: Liu Jian‐Wei , Zhang Shao‐Yi , Qi Hao , Wen Wu‐Cheng , Yu Shu‐Hong 
Published: April 2012

AbstractA family of water/oil interfaces is introduced to provide effective platforms for rapid fabrication of large‐area self‐assembled nanofilms composed of various nanosized building blocks, including nanoparticles (NPs), nanocubes (NC), nanowires (NWs), and nanosheets, at room temperature. As a general interfacial assembly method, NWs and NPs are co‐assembled at the liquid/liquid interface. The as‐prepared co‐assembled Ag NW and Ag NC films show high surface‐enhanced Raman spectroscopy (SERS) intensity, the SERS performance being strongly dependent on the number ratio of the two kinds of nanosized building blocks. The results demonstrate that this interfacial system provides a general method for the assembly of various nanosized building blocks with different shapes and dimensionalities, and thus paves an alternative pathway for further applications of macroscopic assemblies with different functionalities.
Inflation and dark matter in two Higgs doublet models
Authors: Gong Jinn-Ouk , Lee Hyun Min , Kang Sin Kyu 
Published: April 2012

AbstractWe consider the Higgs inflation in the extension of the Standard Model with two Higgs doublets coupled to gravity non-minimally. In the presence of an approximate global U(1) symmetry in the Higgs sector, both radial and angular modes of neutral Higgs bosons drive inflation where large non-Gaussianity is possible from appropriate initial conditions on the angular mode. We also discuss the case with single-field inflation for which the U(1) symmetry is broken to aZ2subgroup. We show that inflationary constraints, perturbativity and stability conditions restrict the parameter space of the Higgs quartic couplings at low energy in both multi- and single-field cases. Focusing on the inert doublet models whereZ2symmetry remains unbroken at low energy, we show that the extra neutral Higgs boson can be a dark matter candidate consistent with the inflationary constraints. The doublet dark matter is always heavy in multi-field inflation while it can be light due to the suppression of the co-annihilation in single-field inflation. The implication of the extra quartic couplings on the vacuum stability bound is also discussed in the light of the recent LHC limits on the Higgs mass.