bluuebunny/crossref_metadata_2025_split huggingface dataset:
Facile and quick synthesis of poly(N‐methylolacrylamide)/polyhedral oligomeric silsesquioxane graft copolymer hybrids via frontal polymerization
Authors: Fang Yuan , Chen Li , Chen Su 
Published: January 2009

AbstractWe report on a new strategy for fabricating well‐defined POSS‐based polymeric materials with and without solvent by frontal polymerization (FP) at ambient pressure. First, we functionalize polyhedral oligomeric silsesquioxane (POSS) with isophorone diisocyanate (IPDI). With these functionalized POSS‐containing isocyanate groups, POSS can be easily incorporated into a poly(N‐methylolacrylamide) (PNMA) matrix via FP in situ. Constant velocity FP is observed without significant bulk polymerization. The morphology and thermal properties of POSS‐based hybrid polymers prepared via FP are comparatively investigated on the basis of scanning electronic microscopy (SEM) and thermogravimetric analysis (TGA). Results show that the as‐prepared POSS‐based polymeric materials exhibit a higher glass transition temperature than that of pure PNMA, ascribing to modified POSS well‐dispersed in these hybrid polymers. Also, the products with different microstructures display different thermal properties. The pure PNMA exhibits a featureless morphology, whereas a hierarchical morphology is obtained for the POSS‐based polymeric materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1136–1147, 2009
Redox, ionic strength, and pH sensitive supramolecular polymer assemblies
Authors: Ghosh Suhrit , Yesilyurt Volkan , Savariar Elamprakash N. , Irvin Katharine , Thayumanavan S. 
Published: January 2009

AbstractFormation of micelle‐type assembly from supramolecular complexation of a surfactant and an oppositely charged homopolymer is demonstrated. The lower CAC observed for these assemblies suggest that the electrostatic interaction provides an amphiphilic homopolymer‐like structure. The stimulus‐induced disassembly of these supramolecular structures has been accomplished with variations in redox characteristics, ionic strength, and pH of the medium. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1052–1060, 2009
Novel thermoplastic elastomers based on arborescent (dendritic) polyisobutylene with short copolymer end sequences
Authors: Puskas Judit E. , Dos Santos Lucas M. , Kaszas Gabor , Kulbaba Kevin 
Published: January 2009

AbstractThis article presents the synthesis and initial characterization of polymers having a high molecular weight dendritic (arborescent) polyisobutylene (arbPIB) core and short end sequences composed of copolymers of isobutylene with isoprene, p‐methyl styrene, or cyclopentadiene. The first stage of the polymerizations was controlled/living (i.e., no chain transfer or irreversible termination were detected) and the process was reproducible. The hydrodynamic radii of arbPIBs were measured by viscometry and quasi‐elastic light scattering, and good agreement between the two methods is demonstrated for the first time in this paper. Sequential addition of the second monomer(s) led to the formation of short copolymer end sequences. We have discovered that regardless of the Tg of the copolymer end blocks, the new block copolymers exhibited TPE properties, which were improved by carbon black and silica fillers to a great extent. These novel PIB‐based TPEs are promising new biomaterials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1148–1158, 2009
The kinetics of enhanced spin capturing polymerization: Influence of the nitrone structure
Authors: Wong Edgar H. H. , Stenzel Martina H. , Junker Tanja , Barner‐Kowollik Christopher 
Published: January 2009

AbstractSeveral nitrones and one nitroso compound have been evaluated for their ability to control the molecular weight of polystyrene via the recently introduced radical polymerization method of enhanced spin capturing polymerization (ESCP). In this technique, molecular weight control is achieved (at ambient or slightly elevated temperatures) via the reaction of a growing radical chain with a nitrone forming a macronitroxide. These nitroxides subsequently react rapidly and irreversibly with propagating macroradicals forming polymer of a certain chain length, which depends on the nitrone concentration in the system. Via evaluation of the resulting number‐average molecular weight, Mn, at low conversions, the addition rate coefficient of the growing radicals onto the different nitrones is determined and activation energies are obtained. For the nitrones N‐tert‐butyl‐α‐phenylnitrone (PBN), N‐methyl‐α‐phenylnitrone (PMN), and N‐methyl‐α‐(4‐bromo‐phenyl) nitrone (pB‐PMN), addition rate coefficients, kad,macro, in a similar magnitude to the styrene propagation rate coefficient, kp, are found with spin capturing constants CSC (with CSC = kad,macro/kp) ranging from 1 to 13 depending on the nitrone and on temperature. Activation energies between 23.6 and 27.7 kJ mol−1 were deduced for kad,macro, congruent with a decreasing CSC with increasing temperature. Almost constant Mn over up to high monomer to polymer conversions is found when CSC is close to unity, while increasing molecular weights can be observed when the CSC is large. From temperatures of 100 °C onward, reversible cleavage of the alkoxyamine group can occur, superimposing a reversible activation/deactivation mechanism onto the ESCP system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1098–1107, 2009
Optimized water‐based ATRP of an anionic monomer: Comprehension and properties characterization
Authors: Mincheva Rosica , Paneva Dilyana , Mespouille Laetitia , Manolova Nevena , Rashkov Iliya , Dubois Philippe 
Published: January 2009

AbstractThe effect of pH and the ligand nature over the atom transfer radical polymerization (ATRP) of the anionic monomer sodium 2‐acrylamido‐2‐methylpropanesulfonate (AMPSNa) was investigated in aqueous medium by using ω‐halogenated poly(ethylene oxide) and CuBr, as macroinitiator and catalyst, respectively. The stability of both catalytic complexes and macroinitiator was investigated in function of pH, that is, fixed between 7.5 and 12. UV‐VIS spectroscopy confirmed a good catalytic complex stability in the studied conditions. Hydrolysis of the macroinitiator ester group at pH higher than 7.5 was detected by 1H NMR and GPC, yielding ill‐defined polymer samples when ATRP is performed in alkaline conditions. 2,2′‐Bipyridyl (Bpy), 1,1,4,7,10,10‐hexamethyltriethylenetetramine (HMTETA), and tris(2‐methylaminoethyl)amine (Me6‐TREN)‐based complexes were compared at the optimal pH (pH 7.5). When polymerization was carried out in the presence of CuBr · 2Me6‐TREN complex block copolymers with narrow molecular weight distribution (1.1 ≤ MW/Mn ≤ 1.3), and good agreement between theoretical and experimental molar masses was obtained. Moreover, increasing the PAMPSNa polymerization degrees (n) did not affect the control over the polymerization. Preliminary characterization of the diblock copolymers behavior in aqueous medium revealed a strong polyelectrolyte effect independently of n. Interestingly, occurrence of interactions between the PEO and PAMPSNa‐blocks was also evidenced by differential scanning calorimetry and thermogravimetric analyses. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1108–1119, 2009
pH and ionic strength responsive polyelectrolyte block copolymer micelles prepared by ring opening metathesis polymerization
Authors: Stubenrauch Kurt , Voets Ilja , Fritz‐Popovski Gerhard , Trimmel Gregor 
Published: January 2009

AbstractWell‐defined amphiphilic block copolymers were prepared by ring opening metathesis polymerization and their stimuli responsive behavior of formed micelles in aqueous solution was investigated. The hydrophobic core of the micelles consists of either a poly[5,6‐bis(ethoxymethyl)bicyclo[2.2.1]hept‐2‐ene]‐block with a glass transition Tg at room temperature or a poly[endo,exo[2.2.1]bicyclohept‐5‐ene‐2,3‐diylbis (phenylmethanone)] with a Tg of 143 °C. For the polyelectrolyte shell, the precursor block poly[endo,exo[2.2.1]bicyclohept‐5‐ene‐2,3‐dicarboxyclic tert‐butylester] was transformed into the free acidic block by cleavage of the tert‐butyl groups using trifluoroacetic acid. Micellar solutions were prepared by dialysis, dissolving the copolymers in dimethyl sulfoxide which was subsequently replaced by water. All polymers form micelles with radii between 10 and 20 nm at a pH‐value below 5, where the carboxylic acid groups are in the protonated state. The block copolymer micelles show a strong increase of the hydrodynamic radius with increasing pH‐value, due to the repulsion among the formed carboxylate anions resulting in a stretching of the polymer chains. In this state, the micelles exhibit responsive behavior to ionic strength where a contraction of the micelles is observed as the carboxylate charges are balanced by sodium ions, whereas no changes of the hydrodynamic radius on addition of salt are observed at low pH. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1178–1191, 2009
Synthesis and self‐organization properties of copolyurethanes based on perylenediimide and naphthalenediimide units
Authors: Jancy B. , Asha S. K. 
Published: January 2009

AbstractA series of perylene and naphthalene diimide‐containing random copolyurethanes with different ratios of perylene/naphthalene diimide content was synthesized and characterized. Copolymerization improved the solubility of these rigid aromatic diimides, and the copolymers were soluble in common organic solvents like chloroform, tetrahydrofuran, and so forth. The absorption spectra of perylene‐based copolymers showed a red‐shifted peak at a wavelength of 557 nm corresponding to J‐type aggregates. For naphthalene copolymers, the quenching of fluorescence at higher naphthalene incorporation suggested the presence of aggregates because of the extensive π‐π stacking of the aromatic core. FTIR spectroscopic analysis showed that the hydrogen bonding tendency of the polymer decreased with increase in perylene/naphthalene incorporation. The fluorescence spectra of the perylene polymers were exactly a mirror image of the absorption spectra. The fluorescence spectra of the naphthalene polymers at higher naphthalene incorporation showed a red‐shifted excimer like emission peak, which was assigned as static excimers based on their excitation spectra. These polymers could exhibit two types of secondary interaction modes, namely, hydrogen bonding (via urethane linkage) and π‐stacking (via aromatic perylene or naphthalene units) thus highlighting the importance of polymer design in inducing self‐organization at both low and high incorporation of the rigid bisimide moieties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1224–1235, 2009
Design and synthesis of new trehalose‐conjugated pentapeptides as inhibitors of Aβ(1–42) fibrillogenesis and toxicity
Authors: De Bona Paolo , Laura Giuffrida Maria , Caraci Filippo , Copani Agata , Pignataro Bruno , Attanasio Francesco , Cataldo Sebastiano , Pappalardo Giuseppe , Rizzarelli Enrico 
Published: January 2009

AbstractAggregation of the amyloid Aβ peptide and its accumulation into insoluble deposits (plaques) are believed to be the main cause of neuronal dysfunction associated with Alzheimer's disease (AD); small molecules that can interfere with the Aβ amyloid fibril formation are therefore of interest for a potential therapeutic strategy. Three new trehalose‐conjugated peptides of the well known β‐sheet breaker peptide iAβ5p, were synthesized. The disaccharide was covalently attached to different sites of the LPFFD peptide chain, i.e. at the N‐terminus, C‐terminus or at the Asp side chain. CD spectroscopy in different solvents was used to assess changes in the peptide conformation of these compounds. The effects of these glycopeptides on the self‐assembly and morphology of Aβ aggregates were investigated by ThT fluorescence assay and dynamic Scanning Force Microscopy, respectively. All the synthesized compounds were tested as inhibitors of Aβ toxicity toward pure cultures of rat cortical neurons. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.
Knowledge‐based reliability assessments for time‐varying climates
Authors: Monroe Eric M. , Pan Rong 
Published: January 2009

AbstractA method of obtaining a set of closed‐form solutions for reliability acceleration factors under time‐varying temperature/humidity environments is presented. This paper outlines the procedure for generating such equations based on National Oceanographic and Atmospheric Administration climatic data. Results from Phoenix, Arizona are used as a case study. Predictions from these closed‐form solutions are compared with traditional reliability assessments and exact solutions using raw ambient temperature and humidity values. Copyright © 2008 John Wiley & Sons, Ltd.
Dynamics simulation on the flexibility and backbone motions of HP1 chromodomain bound to free and lysine 9‐methylated histone H3 tails
Authors: Jiang Yanke , Zou Jianwei , Zeng Min , Zhang Na , Yu Qingsen 
Published: January 2009

AbstractHistone methylation has emerged as a central epigenetic modification with both activating and repressive roles in eukaryotic chromatin. Drosophila HP1 (heterochromatin‐associated protein 1) is one of the chromodomain proteins that contain the essential aromatic residues as the recognition pocket for lysine methylated histone H3 tail. The aromatic cage indicates that the complex of chromodomain protein binding lysine methylated histone H3 tail can be seen as a typical host–guest system between protein and protein. About 10‐ns molecular dynamics simulations have been carried out in this study to examine how the presence of mono‐, trimethylated lysine 9 histone H3 tail (Me1K9, Me3K9 H3) influences the motions of HP1 protein receptor. The study shows that the conformation of HP1 protein free of H3 tail easily changes, whereas that of HP1 protein bound to methylated H3 tail does not. But the conformation of inserted Me1K9 H3 changes obviously as the Me1K recognition makes hydrogen‐bonded interactions associated with the aromatic cage even more unstable than those in free HP1 protein. The conformational change of Me1K9 H3 is correlated with the motions of HP1 protein. As the recognition factor going from Me1K to Me3K produces a more favorable interaction for aromatic ring, hydrogen‐bonded interactions associated with aromatic cage in Me3K9 H3‐HP1 complex were observed to be much more stable than those in Me1K9 H3‐HP1 complex and free HP1. Because of correlation, the flexibility of Me3K9 H3 decreases. The simulations indicate that both the MeK and the surrounding histone tail sequence are necessary features of recognition which significantly affect the flexibility and backbone motions of HP1 chromodomain. These findings confirm a regulatory mechanism of protein–protein interactions through a trimethylated post‐translational modification. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Some considerations about Gaussian basis sets for electric property calculations
Authors: Arruda Priscilla M. , Canal Neto A. , Jorge F. E. 
Published: January 2009

AbstractRecently, segmented contracted basis sets of double, triple, and quadruple zeta valence quality plus polarization functions (XZP, X = D, T, and Q, respectively) for the atoms from H to Ar were reported. In this work, with the objective of having a better description of polarizabilities, the QZP set was augmented with diffuse (s and p symmetries) and polarization (p, d, f, and g symmetries) functions that were chosen to maximize the mean dipole polarizability at the UHF and UMP2 levels, respectively. At the HF and B3LYP levels of theory, electric dipole moment and static polarizability for a sample of molecules were evaluated. Comparison with experimental data and results obtained with a similar size basis set, whose diffuse functions were optimized for the ground state energy of the anion, was done. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Design of middleware for tele‐homecare systems
Authors: Lu Hsi‐Feng , Chen Jiann‐Liang 
Published: January 2009

AbstractThis work proposes a novel middleware architecture for tele‐homecare systems. The proposed architecture is composed of three layers: a device management layer, a data management layer and an application layer. Vital signs sensing is achieved by wired and wireless sensor node integrated with a medical device, or by sensors connected with serial link. Although defined as the software above the medical sensor network, the two‐layer middleware is below the application program that provides a common programming abstraction for tele‐homecare systems. An application,called the Tele‐Homecare Household Monitor System, based on the proposed middleware is implemented and evaluated. The transmission energy costs (the number of messages transmitted in the system) and the average delays caused by aggregation function are compared in two configurations and four different implementations of aggregation function. To increase power efficiency and prolong the system life‐time, the aggregation functions should be implemented on the sensor node of the wireless sensor network if this is feasible. To minimize the message delay, the aggregation functions should be implemented on cluster head. Good message aggregation and filtering significantly reduce the number of messages transmitted and stored in the system, and could translate the sensed readings into useful and meaningful information. Copyright © 2009 John Wiley & Sons, Ltd.
Selective Nonoperative Management of Kidney Gunshot Injuries
Authors: Navsaria Pradeep H. , Nicol Andrew J. 
Published: January 2009

AbstractBackgroundNonoperative management (NOM) of kidney gunshot injuries as an alternative to surgical exploration is rarely reported. The aim of this study was to assess the feasibility and safety of selective NOM of such injuries.MethodsA 4‐year prospective study was conducted that included all patients admitted to a Level I trauma center with kidney gunshot injuries. Patients with abdominal gunshot wounds and hematuria with no indications for immediate laparotomy (peritonitis, hemodynamic instability, head or spinal cord injury) underwent intravenous contrast abdominal computed tomography. Patients with confirmed kidney injuries were observed with serial clinical examinations. Outcome parameters included the need for delayed laparotomy, complications, length of hospital stay, and survival.ResultsDuring the study period, 33 patients with kidney gunshot injuries were selected for NOM without laparotomy. The mean Injury Severity Score was 10.5 (range 4–25). Simple kidney injuries (grades I, II) occurred in 15 (45.5%) patients and complex kidney injuries (grades III, IV) in 18 (54.5%) patients. Associated injuries included 14 of the liver (42.4%), 4 (12.1%) of the spleen, and 6 (18.2%) each of the diaphragm, lung (contusion), and hemothorax. Three patients required delayed laparotomy: two for nonrenal indications, and one patient had a delayed nephrectomy for a grade IV injury. The overall successful NOM rate was 90.9%. The mean hospital stay was 5.9 days (range 2–23 days). There were no kidney‐related complications and no mortality.ConclusionSelective NOM of patients with kidney gunshot injuries is a feasible, safe, effective alternative to routine exploration.
Living at Risk: The Sibling's Perspective of Early‐Onset Alzheimer's Disease
Authors: Wain Karen E. , Uhlmann Wendy R. , Heidebrink Judith , Roberts J. Scott 
Published: January 2009

AbstractEarly‐onset Alzheimer's disease (EOAD) is an increasingly diagnosed condition and is associated with genetic risk factors. This is one of the first studies exploring the lived experience of siblings of individuals with EOAD. We used structured questionnaires and semi‐structured interviews to assess a broad range of siblings’ experiences with and beliefs about EOAD, including knowledge, perceptions of personal risk, level of worry, and effects on life decisions. Participants (n = 24) were predominantly female (62.5%) and middle‐aged (mean = 56.8 years; range 37–83). When asked about risk factors, genetics was cited most frequently (62.5%). Several potential means of reducing AD risk were endorsed, with 54% reporting engagement in behaviors for this purpose (e.g., keeping mentally active). Participants ranged widely in their perceived personal risk of AD (range: 0–100; mean = 35.6%), with higher perceived risk associated with worry about AD (p < 0.01). Understanding siblings’ experiences with EOAD can inform how genetic counselors and healthcare professionals work with this population to facilitate risk communication and decision‐making about testing and healthcare.
Geoducks (Panopea abrupta) as isotopic bioarchives of seasonality in the climate of British Columbia
Authors: Nielsen Jan Kresten , Nielsen Jesper Kresten 
Published: January 2009

AbstractGeochemical analyses of geoduck shells (Panopea abrupta) have yielded new high‐resolution isotope records of individual growth increments. The geoducks, which were collected from Parry Passage at Langara Island, British Columbia, are the most northern specimens that have yet been analyzed for stable oxygen and carbon isotopes. The isotope records represent the entire shell growth during the calendar years 1918, 1987, and 1991. The analyses showed that values of δ18Oshell and δ13Cshell vary within their growth increments. Temperature derived from δ18Oshell is consistent with modern instrumental data of sea‐surface temperature. High‐resolution δ18O records from individual growth increments substantiate the assumption that they are formed annually. The instrumental data indicate that the growth season was from May through October/November. The sea temperature became gradually warmer during the beginning of the growth season, and decreased steeply during autumn. Similar subannual trends can be recognized in shells growing almost a century ago. Correlation between δ18Oshell and δ13Cshell is negative for 1917–1919 and 1986–1988, whereas the correlation is positive for 1990–1992. Differences in correlation may be related to the composition of available food particles, i.e., algal blooms and plant debris. The food composition is partially affected by the Pacific Decadal Oscillation (PDO). These findings have major implications for the understanding of the interpretation of carbon isotopes in marine bivalves. Because of their spatial and temporal distribution, the geoduck shells are highly suitable for oceanographic reconstructions using stable‐isotope analysis and sclerochronology. Furthermore, the large shell size and thickness and their deeply buried life position suggest a high preservation potential in ancient deposits. It is well known that the genus Panopea has a long‐range fossil record.