bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonclassical forces: Seemingly insignificant but a powerful tool to control macromolecular structures
Authors: Fujiki Michiya , Saxena Anubhav 
Published: June 2008

AbstractStrong chemical forces such as covalent and ionic bonds are responsible for building discrete molecules, nature dwells on noncovalent forces weaker by three orders in magnitude, like the hydrophobic effect, hydrogen bonding, and van der Waals forces. Despite being weak, they possess the potential to drive spontaneous folding or unfolding of proteins and nucleic acids and the recognition between complimentary molecular surfaces. The power of these forces lies in the cooperativity with which they act, thereby generating a cumulative effect of many bonding interactions occurring together. Many ongoing research aims to translate the potential of these forces to the synthetic world to create desired structures with specific chemical functions. Achieving this offers unlimited opportunities for designing and synthesizing the most complex structures with specific applications. This highlight aims to reflect the critical role these noncovalent forces play in controlling macromolecular structures, which hold immense untapped potential for applications defying conventions, and briefly touches on the concept of homochirality in nature based on chiral and weak noncovalent interactions in synthetic nonpolar Si‐catenated polymers. It sheds some light on the discovery and characterization of Si/F‐C interactions in fluoroalkylated polysilanes in chemosensing of fluoride ions and nitroaromatics with a great sensitivity and selectivity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4637–4650, 2008
Poly(glycerin 1,3‐dimethacrylate)‐based monolith with a bicontinuous structure tailored as HPLC column by photoinitiated in situ radical polymerization via viscoelastic phase separation
Authors: Aoki Hiroshi , Tanaka Nobuo , Kubo Takuya , Hosoya Ken 
Published: June 2008

AbstractIn this article we described our new approach to the polymer monolith with its morphology tailored for HPLC application to small solutes such as drug candidates. We prepared polymer monoliths based on glycerin 1,3‐dimethacrylate, GDMA with a bicontinuous structure by in situ photoinitiated free radical polymerization (UV irradiation at 365 nm). Our photopolymerization was carried out with a monodispese ultra high molecular weight polystyrene solution in chlorobenzene uniquely formulated as a porogen. The poly‐GDMA monoliths in bulk, rod and capillary thus prepared showed a bicontinuous network‐like structure featured by their fine skeletal thickness nearly in sub μm size. This monolithic structure was considered as a time‐evolved morphology frozen by UV‐irradiation via viscoelastic phase separation induced by the said porogenic polystyrene solution. According to our μHPLC measurement with acetophenone as a model solute, the UV prepared poly‐GDMA capillary demonstrated a much shaper elution profile affording higher column efficiency and permeability as compared with the thermally prepared capillary of the same bore size. Our investigation showed experimentally that poly‐GDMA monoliths with a well‐defined bicontinuous structure could be prepared reproducibly by photoinitiated radical polymerization via viscoelastic phase separation using the said unique porogen. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4651–4673, 2008
Synthesis and properties of triaryl diamine‐based hole‐transporting monomer and polymer
Authors: Tomkeviciene A. , Simokaitiene J. , Grazulevicius J. V. , Jankauskas V. 
Published: June 2008

AbstractThe synthesis and properties of hole‐transporting triaryl diamine‐based low‐molar‐mass compounds and polymer are reported. Comparative study on their thermal, optical, and photoelectrical properties is presented. All the synthesized compounds are found to form glasses with the glass transition temperatures in the range of 43–119 °C as characterized by differential scanning calorimetry. The ionization potentials of these compounds range from 5.31 to 5.40 eV as determined by electron photoemission method. Hole‐drift mobilities in the films of the synthesized compounds were estimated by the xerographic time‐of‐flight technique. They were found to reach 10−3 cm2/Vs at electric field of 6.4 × 105 V/cm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4674–4680, 2008
Structure and activity transition of lysozyme on interacting with and releasing from polyelectrolyte with different hydrophobicity
Authors: Gao Gao , Yao Ping 
Published: June 2008

AbstractThe complexes of lysozyme with poly(isobutylene‐alt‐maleic acid) (PIMA) and poly(1‐tetradecene‐alt‐maleic acid) (PTMA) at pH 7.4 were characterized using static and dynamic light scattering. The electrostatic interaction of PIMA with lysozyme results in a loose complex structure, while the electrostatic and hydrophobic interactions between PTMA and lysozyme produce a compact complex structure. Lysozyme in PIMA complex particles remains a part of activity and structure analyzed by circular dichroism and substrate hydrolysis. However, lysozyme loses its tertiary structure and activity completely in PTMA complex. NaCl is more effective to dissociate PIMA–lysozyme complex by screening the electrostatic interaction, whereas GdHCl is more effective to dissociate PTMA–lysozyme complex by forming GdHCl–PTMA precipitates through extra hydrophobic interactions. In the release process, the denatured lysozyme molecules are able to avoid hydrophobic aggregation and fully regenerate their native structure and activity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4681–4690, 2008
Preparation and microstructural analysis of poly(lactic‐alt‐glycolic acid)
Authors: Stayshich Ryan M. , Meyer Tara Y. 
Published: June 2008

AbstractAlternating copolymers of glycolic (G) and lactic (L) acid were prepared by the condensation of the preformed dimers: LLG and LracG. By size exclusion chromatography (THF, PS standards), poly(LLG) exhibited a molecular weight (Mn) of 15.6 kg mol−1, with a weight average molecular weight (Mw) of 26.9 kg mol−1 and a PDI of 1.72. The Mn for poly(LracG) was 9.2 kg mol−1, with a Mw of 12.9 kg mol−1 and a PDI of 1.40. The NMR spectra of poly(LLG) were consistent with an isotactic microstructure. NMR spectra of the racemic poly(LracG) were consistent with an atactic structure. The methylene region of the 1H NMR spectrum showed a tetrad level of resolution of the nearby stereochemical relationships, for example, iii. Resonances for other groups in both the 1H and 13C NMR spectra gave only a triad level of resolution. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4704–4711, 2008
Self‐assembly of metallo‐supramolecular block copolymers in thin films
Authors: Fustin Charles‐André , Guillet Pierre , Misner Matthew J. , Russell Thomas P. , Schubert Ulrich S. , Gohy Jean‐François 
Published: June 2008

AbstractThe self‐assembly of a metallo‐supramolecular PS‐[Ru]‐PEO block copolymer, where ‐[Ru]‐ is a bis‐2,2′:6′,2″‐terpyridine‐ruthenium(II) complex, in thin films was investigated. Metallo‐supramolecular copolymers exhibit a different behavior as compared to their covalent counterparts. The presence of the charged complex at the junction of the two blocks has a strong impact on the self‐assembly, effecting the orientation of the cylinders and ordering process. Poly(ethylene oxide) cylinders oriented normal to the film surface are obtained directly regardless of the experimental conditions over a wide range of thicknesses. Exposure to polar solvent vapors can be used to improve the lateral ordering of the cylindrical microdomains. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4719–4724, 2008
Controlled cationic polymerization of cyclopentadiene with B(C6F5)3 as a coinitiator in the presence of water
Authors: Kostjuk Sergei V. , Radchenko Alexei V. , Ganachaud François 
Published: June 2008

AbstractThe controlled cationic polymerization of cyclopentadiene (CPD) at 20 °C using 1‐(4‐methoxyphenyl)ethanol (1)/B(C6F5)3 initiating system in the presence of fairly large amount of water is reported. The number–average molecular weights of the obtained polymers increased in direct proportion to monomer conversion in agreement with calculated values and were inversely proportional to initiator concentration, while the molecular weight distribution slightly broadened during the polymerization (Mw/Mn ∼ 1.15–1.60). 1H NMR analyses confirmed that the polymerization proceeds via reversible activation of the COH bond derived from the initiator to generate the growing cationic species, although some loss of hydroxyl functionality happened in the course of the polymerization. It was also shown that the enchainment in cationic polymerization of CPD was affected by the nature of the solvent(s): for instance, polymers with high regioselectivity ([1,4] up to 70%) were obtained in acetonitrile, whereas lower values (around 60%) were found in CH2Cl2/CH3CN mixtures. Aqueous suspension polymerization of CPD using the same initiating system was successfully performed and allowed to synthesize primarily hydroxyl‐terminated oligomers (Fn = 0.8–0.9) with Mn ≤ 1000 g mol−1 and broad MWD (Mw/Mn ∼ 2.2). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4734–4747, 2008
Local forms of molecular mobility in copolymethacrylates containing side‐chain nonlinear optical chromophores
Authors: Nikonorova Natalia A. , Smirnov Nikolai N. , Diaz‐Calleja Ricardo , Yakimansky Alexander V. 
Published: June 2008

AbstractLocal forms of molecular mobility of comb‐like random copolymethacrylates, containing side‐chain nonlinear optical chromophores and amyl‐ or octafluoroamyl‐groups, are studied. In the glassy state, two relaxation processes are found, which are due to reorientation of terminal polar groups (γ2‐process) and rotation of chromophore groups about their long axes (β‐process). For octafluoroamyl‐containing copolymers, the γ2‐process is superposition of the two molecular motions due to reorientation of terminal chromophore groups and CF2H groups. The intensity and relaxation times in the range of the γ2‐process depend on the chemical structure and concentration of chromophores in a copolymer. For the β‐process, the molecular mobility weakly depends on the chromophore structure, being mainly determined by the relative lengths of the rigid chromophore and flexible side chains. On the global spectrum of depolarization current it was observed the γ1‐process due to reorientation of (CH2)n spacers between chromophore groups and copolymer backbone. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1488–1496, 2008
Structural and conformational changes during thermally‐induced crystallization of poly(trimethylene terephthalate) by infrared spectroscopy
Authors: Yamen Mustafa , Ozkaya Sabahattin , Vasanthan Nadarajah 
Published: June 2008

AbstractConformational changes occurring during thermally‐induced crystallization of poly(trimethylene terephthalate) (PTT) by annealing have been studied using density measurement, differential scanning calorimetry (DSC), and mid‐infrared spectroscopy (MIR). Infrared spectra of amorphous and semicrystalline PTT were obtained, and digital subtraction of the amorphous contribution from the semicrystalline PTT spectra provided characteristic MIR spectra of amorphous and crystalline PTT. The normalized absorbance of 1577, 1173, and 976 cm−1 were plotted against the crystallinity showing that these bands can be used unambiguously to represent the trans conformation while the band at 1358 cm−1 can be used to represent gauche conformation of methylene segment. The presence of a weak band at 1358 cm−1 in the amorphous spectrum suggested that a small amount of gauche conformation is present in the amorphous phase. Infrared spectroscopy has been used for the first time as a means to estimate the trans and gauche conformations of methylene segments in PTT as a function of Ta. The amount of gauche conformation was plotted against the crystalline fraction and the extrapolation of this plot to zero crystalline fraction provided a value of 0.07, suggested that the pure amorphous phase consist of ∼ 7% gauche conformation. It was found that the amorphous and crystalline gauche conformation increases at the expense of amorphous trans conformation during thermally induced crystallization of PTT. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1497–1504, 2008
The effect of interfacial viscosity on the droplet dynamics under flow field
Authors: Yu Wei , Zhou Chixing 
Published: June 2008

AbstractThe effects of interfacial viscosity on the droplet dynamics in simple shear flow and planar hyperbolic flow are investigated by numerical simulation with diffuse interface model. The change of interfacial viscosity results in an apparent slip of interfacial velocity. Interfacial viscosity has been found to have different influence on droplet deformation and coalescence. Smaller interfacial viscosity can stabilize droplet shape in flow field, while larger interfacial viscosity will increase droplet deformation, or even make droplet breakup faster. Different behavior is found in droplet coalescence, where smaller interfacial viscosity speeds up film drainage and droplet coalescence, but larger interfacial viscosity postpones the film drainage process. This is due to the change of film shape from flat‐like for smaller interfacial viscosity to dimple‐like for larger interfacial viscosity. The film drainage time still scales as Ca0 at smaller capillary number (Ca), and Ca1.5 at higher capillary number when the interfacial viscosity changes. The interfacial viscosity only affects the transition between these limiting scaling relationships. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1505–1514, 2008
Self‐assembly in solutions of block and random copolymers during metal nanoparticle formation
Authors: Meristoudi A. , Pispas S. , Vainos N. 
Published: June 2008

AbstractThe self‐assembly behavior of poly(isoprene‐b‐acrylic acid) and poly(styrene‐b‐2‐vinylpyridine) amphiphilic block copolymers, as well as a poly(styrene‐r‐2‐vinylpyridine) amphiphilic random copolymer was investigated in slightly selective organic solvents (tetrahydrofuran and toluene) in the presence of Ag and Au ions and subsequently Ag, Au metal nanoparticles, by means of dynamic light scattering. In the range of concentrations studied the copolymers exist in the form of micelles with cores composed of acrylic acid and 2‐vinylpyridine segments in equilibrium with unimers. The addition of metal ions and their subsequent transformation to metal nanoparticles shifts the equilibrium in favor of the micelles. The concentration of the inorganic components has also a considerable effect on the size of the polymeric aggregates. A similar behavior is observed for the random copolymer. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), UV‐visible spectroscopy, and transmission electron microscopy (TEM) give valuable additional information on the nature of the interactions between the polymeric and inorganic components, as well as on the characteristics of the metal nanoparticles and the hybrid micelles formed in each case. The presented results have a direct relation to the synthesis of metal nanoparticles under confinement by utilization of copolymer nanoreactors and appropriate solution conditions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1515–1524, 2008
Fluorination of Polymers by Means of He/CF4‐Fed Atmospheric Pressure Glow Dielectric Barrier Discharges
Authors: Fanelli Fiorenza , Fracassi Francesco , d'Agostino Riccardo 
Published: June 2008

AbstractHe/CF4‐fed GDBDs were used to fluorinate PP and PET. The effect of various process parameters on the polymers surface composition and morphology, as well as on their wettability was investigated inside the GDBD existence domain. An extensive surface fluorination of treated polymers due to the grafting of F atoms and CFx radicals was observed. The increase of CF4 concentration in the feed, of treatment duration, and of excitation frequency resulted in an increase of the fluorination degree corresponding to F/C ratios as high as 1.18 and 1.22 for PP and PET, respectively. The emission spectra of GDBDs fed by helium in mixture with CF4, CHF3, C2F6 and C3F8 were compared.magnified image
Characterization of Microwave Plasma Torch for Decontamination
Authors: Shimizu Tetsuji , Steffes Bernd , Pompl René , Jamitzky Ferdinand , Bunk Wolfram , Ramrath Katrin , Georgi Matthias , Stolz Wilhelm , Schmidt Hans‐Ulrich , Urayama Takuya , Fujii Shuitsu , Morfill Gregor Eugen 
Published: June 2008

AbstractAn atmospheric low‐temperature microwave plasma torch has been developed and applied to disinfection. The size of the plasma output is relatively large (35 mm in diameter). Ar gas at a flow rate of 2.2 slm and 85 W microwave power are used. Plasma discharges are produced between the tip of each electrode and the inner surface of the cylinder. When an Escherichia coli culture is placed for 2 min at 20 mm below the torch, where the gas temperature is sufficiently cool, the bacteria are almost completely killed within a 40 mm diameter circle. The UV radiation is one of the major players responsible for killing bacteria, others being the reactive species and the charged particles.magnified image
Early stages of β2‐microglobulin aggregation and the inhibiting action of αB‐crystallin
Authors: Pullara Filippo , Emanuele Antonio 
Published: June 2008

AbstractStatic and dynamic light scattering experiments on extremely clean (nanofiltered) samples of the well‐known amyloidogenic protein β2‐microglobulin (R3Aβ2m and WTβ2m) evidence the self‐assembly of early aggregates showing unexpected features. Further, we find that αB‐crystallin effectively inhibits aggregation of β2m in a far less than stoichiometric proportion, from 1:60 αB‐crystallin monomer to β2m monomer ratio, down to at least a 1:2 × 103 αB‐crystallin oligomerto β2m monomer ratio. Therefore, inhibition of the early stage of β2m aggregation by αB‐crystallin does not necessarily require a mechanicistic chaperon‐like action implying one‐to‐one binding. This highlights the role of the free energy landscape of the system and of related modifications of solute–solvent thermodynamics caused by co‐solutes, in agreement with recent work from our and other laboratories. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Characterization of a sHsp of Schizosaccharomyces pombe, SpHsp15.8, and the implication of its functional mechanism by comparison with another sHsp, SpHsp16.0
Authors: Sugino Chika , Hirose Maya , Tohda Hideki , Yoshinari Yukiko , Abe Tetsuya , Giga‐Hama Yuko , Iizuka Ryo , Shimizu Masafumi , Kidokoro Shun‐ichi , Ishii Noriyuki , Yohda Masafumi 
Published: June 2008

AbstractThere exist two small heat shock proteins (sHsps) in the fission yeast, Schizosaccharomyces pombe (S. pombe), whose expressions are highly induced by heat stress. We have previously expressed, purified, and characterized one of the sHsps, SpHsp16.0. In this study, we examined the other sHsp, SpHsp15.8. It suppressed the thermal aggregation of citrate synthase (CS) from porcine heart and dithiothreitol‐induced aggregation of insulin from bovine pancreas with very high efficiency. Almost one SpHsp15.8 subunit was sufficient to protect one protein molecule from aggregation. Like SpHsp16.0, SpHsp15.8 dissociated into small oligomers and then interacted with denatured substrate proteins. SpHsp16.0 exhibited a clear enthalpy change for denaturation occurring over 60°C in differential scanning calorimetry (DSC). However, we could not observe any significant enthalpy change in the DSC of SpHsp15.8. The difference is likely to be caused by the adhesive characteristics of SpHsp15.8. The oligomer dissociation of SpHsp15.8 and SpHsp16.0 and their interactions with denatured substrate proteins were studied by fluorescence polarization analysis (FPA). Both sHsps exhibited a temperature‐dependent decrease of fluorescence polarization, which correlates with the dissociation of large oligomers to small oligomers. The dissociation of the SpHsp15.8 oligomer began at about 35°C and proceeded gradually. On the contrary, the SpHsp16.0 oligomer was stable up to ∼45°C, but then dissociated into small oligomers abruptly at this temperature. Interestingly, SpHsp16.0 is likely to interact with denatured CS in the dissociated state, while SpHsp15.8 is likely to interact with CS in a large complex. These results suggest that S. pombe utilizes two sHsps that function in different manners, probably to cope with a wide range of temperatures and various denatured proteins. Proteins 2009. © 2008 Wiley‐Liss, Inc.
The unintended effects of interactive objects and labels in the science museum
Authors: Atkins Leslie J. , Velez Lisanne , Goudy David , Dunbar Kevin N. 
Published: June 2008

AbstractWhat effects do different setups of museum exhibits have on visitors' conversations and interactions? The study reported here is an investigation of the role that labels and associated materials play in visitors' conversations and interactions at a heat camera exhibit. After we introduced a label to help visitors explore the insulating properties of clothing, we found a dramatic shift in the kinds of activities and participation structures of visitors. Not only were visitors, as expected, discussing why clothing was warm, but they were doing so in a fashion more consistent with formal education than the typically more collaborative conversations seen in informal learning environments. Overall, our analyses reveal that labels and activities presented serve to frame both the activities that visitors engage in and the types of conversations that ensue and that this has deep influences on visitors' experiences at the exhibit. © 2008 Wiley Periodicals, Inc.Sci Ed93:161–184, 2009
Impact of a multiyear professional development intervention on science achievement of culturally and linguistically diverse elementary students
Authors: Lee Okhee , Deaktor Rachael , Enders Craig , Lambert Julie 
Published: June 2008

AbstractThis study examined the impact of the 3‐year implementation of a professional development intervention on science achievement of culturally and linguistically diverse elementary students. Teachers were provided with instructional units and workshops that were designed to improve teaching practices and foster positive beliefs about science and literacy with diverse student groups. The study involved third, fourth, and fifth grade students at six elementary schools in a large urban school district during the 2001 through 2004 school years. Significance tests of mean scores between pre‐ and posttests indicated statistically significant increases each year on all measures of science at all three grade levels. Achievement gaps among demographic subgroups sometimes narrowed among fourth grade students and remained consistent among third and fifth grade students. Item‐by‐item comparisons with NAEP and TIMSS samples indicated overall positive performance by students at the end of each school year. The consistent patterns of positive outcomes indicate the effectiveness of our intervention in producing achievement gains at all three grade levels while also reducing achievement gaps among demographic subgroups at the fourth grade. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 45: 726–747, 2008