bluuebunny/crossref_metadata_2025_split huggingface dataset:
PARACEST MRI with improved temporal resolution
Authors: Liu Guanshu , Ali M. Meser , Yoo Byunghee , Griswold Mark A. , Tkach Jean A. , Pagel Mark D. 
Published: January 2009

AbstractPARAmagnetic Chemical Exchange Saturation Transfer (PARACEST) is a novel contrast mechanism for MRI. A PARACEST MRI methodology with high temporal resolution is highly desired for in vivo MRI applications of molecular imaging. To address this need, a strategy has been developed that includes a long selective saturation period before each repetition of a Rapid Acquisition with Relaxation Enhancement (RARE) pulse sequence. This strategy is suitable for the application of PARACEST contrast agents to environments with long T1 relaxation times. An alternative strategy uses short selective saturation periods before the acquisition of each k‐space trajectory to maintain steady state conditions, which can be implemented with a Fast Low Angle Shot (FLASH) pulse sequence. These short saturation periods lengthen the total scan time as compared to the first approach but compensate for the loss in PARACEST contrast related to T1 relaxation. Both approaches have been demonstrated in vitro and in vivo with significantly improved temporal resolutions as compared to a conventional gradient‐echo PARACEST method without sacrificing CNR efficiency. These demonstrations also adopted a strategy for measuring the PARACEST effect that only requires selective saturation at a single MR frequency, which further improves temporal resolution for PARACEST detection. Magn Reson Med 61:399–408, 2009. © 2009 Wiley‐Liss, Inc.
Axial black blood turbo spin echo imaging of the right ventricle
Authors: Berkowitz Seth J. , Macedo Robson , Malayeri Ashkan A. , Shea Steven M. , Lorenz Christine H. , Calkins Hugh , Vogel‐Claussen Jens , Tandri Harikrishna , Bluemke David A. 
Published: January 2009

AbstractBlack blood turbo spin echo (TSE) imaging of the right ventricle (RV) free wall is highly sensitive to cardiac motion, frequently resulting in nondiagnostic images. Temporal and spatial parameters of a black blood TSE pulse sequence were evaluated for visualization of the RV free wall. Seventy‐four patient studies were retrospectively evaluated for the effects of acquisition timing on image quality. Axial black blood TSE images were acquired on 10 healthy volunteers to assess the role of spatial misregistration on right ventricle visualization; increasing the double inversion recovery (DIR) slice thickness beyond 300% had no effect on image quality (P = 0.2). Thirty‐five patient studies were prospectively evaluated with inversion times (TIs) corresponding to the mid‐diastolic rest period and end‐systole based on visual analysis of a four chamber cine. When TIs were chosen to be within the patients' RV rest period, mean image quality score was significantly improved (2.3 vs 1.86; P < 0.001) and the number of clinically diagnostic images increased from 32% to 46%. Black blood TSE imaging of the RV free wall is highly sensitive to cardiac motion. Image quality can be improved by choosing TIs concordant with the rest period of the patient's RV that may occur at mid‐diastole or end‐systole. Magn Reson Med 61:307–314, 2009. © 2009 Wiley‐Liss, Inc.
Comorbidities of Advanced Lung Disease
Authors: Nations Joel Anthony , Nathan Steven D. 
Published: January 2009

AbstractLung disease in advanced stages is often accompanied by multiple comorbidities. Often, these processes lead to significant morbidity and occasionally mortality. Symptoms of pulmonary comorbidities, including pulmonary embolus, pulmonary hypertension, sleep‐disordered breathing, and lung malignancy, may be intertwined with symptoms of advancing lung disease. However, the occurrence of extrapulmonary processes, including depression, diabetes mellitus, osteoporosis, and gastroesophageal reflux disease, may be subtle. Clinicians caring for advanced lung disease should be aware of the many comorbid processes that may accompany advancing lung disease. Mt Sinai J Med 76:53–62, © 2009 Mount Sinai School of Medicine
On the accuracy of finite volume and discontinuous Galerkin discretizations for compressible flow on unstructured grids
Authors: Nogueira X. , Cueto‐Felgueroso L. , Colominas I. , Gómez H. , Navarrina F. , Casteleiro M. 
Published: January 2009

AbstractThis paper presents a comparison between two high‐order methods. The first one is a high‐order finite volume (FV) discretization on unstructured grids that uses a meshfree method (moving least squares (MLS)) in order to construct a piecewise polynomial reconstruction and evaluate the viscous fluxes. The second method is a discontinuous Galerkin (DG) scheme. Numerical examples of inviscid and viscous flows are presented and the solutions are compared. The accuracy of both methods, for the same grid resolution, is similar, although the DG scheme requires a larger number of degrees of freedom than the FV–MLS method. Copyright © 2009 John Wiley & Sons, Ltd.
Polymers containing in‐chain quinone moieties: synthesis and properties
Authors: Hodge Philip , Gautrot Julien E 
Published: January 2009

AbstractThe redox properties of quinones play a key part in photosynthesis and oxidative phosphorylation. This mini‐review focuses on the synthesis and properties of polymers that contain in‐chain quinone units. Many of the syntheses exploit Yamamoto or Suzuki couplings. Most of the polymers that are soluble in organic solvents display interesting electrochemical and optical properties that may be useful for a wide range of applications. Copyright © 2009 Society of Chemical Industry
Heterogeneous ring‐opening polymerization of lactones for biomedical applications
Authors: Khan Javaid H , Schue Francois , George Graeme A 
Published: January 2009

AbstractCatalysis of the ring‐opening reaction of L‐lactide and ε‐caprolactone to form the corresponding biodegradable polyesters is frequently performed using organometallic compounds such as tin(II) 2‐ethylhexanoate, which operates by a living, coordination insertion mechanism. For biomedical applications, non‐toxic calcium salts have been researched but these rarely approach the same efficiency. The use of heterogeneous immobilized catalysts offers an alternative approach, but competing reactions such as transesterification affect the final molecular weight and polydispersity. The formation of hybrid materials by using silica as the initiation site offers the prospect of biomaterials with novel properties. Copyright © 2009 Society of Chemical Industry
Effects of filler geometry on internal structure and physical properties of polycarbonate composites prepared with various carbon fillers
Authors: Lee Seung Hwan , Kim Jong Hyuk , Choi Sheong Hyun , Kim Seong Yun , Kim Kyeong Wung , Youn Jae Ryoun 
Published: January 2009

AbstractBACKGROUND: The effects of filler geometry are important for understanding the internal structure and physical properties of polymer composites. To investigate the effects of filler geometry on electrical conductivity as well as morphological and rheological properties, three types of polycarbonate (PC) composites were prepared by melt compounding with a twin‐screw extruder.RESULTS: The electrical conductivity of PC/carbon black (CB) and PC/graphite (carbon) nanofibre (CNF) composites did not show a percolation threshold through the entire filler loading ranges. However, PC‐blend‐carbon nanotube (CNT) composites showed a percolation electrical threshold for a filler loading of 1.0 to 3.0 wt% and their maximum electrical conductivity approached 10−3 S m−1. PC‐blend‐CB and PC‐blend‐CNF composites showed Newtonian behaviour like pure PC matrix, but PC‐blend‐CNT composites showed yield stress as well as increased storage modulus and strong shear thinning behaviour at low angular frequency and shear rate due to strong interactions generated between CNT–CNT particles as well as PC molecules and CNT particles on the nanometre scale.CONCLUSIONS: The electrical conductivity of the PC composites with different carbon constituents was well explained by the continuous network structure formed between filler particles. The network structure was confirmed by the good dispersion of fillers as well as by the yield stress and solid‐like behaviour observed in steady and dynamic shear flows. Copyright © 2009 Society of Chemical Industry
Synthesis and properties of hydroxyapatite nanorod‐reinforced polyamide 6 nanocomposites
Authors: Li Lanjie , Yang Guisheng 
Published: January 2009

AbstractBACKGROUND:Polyamide 6 (PA6)/hydroxyapatite (HA) nanocomposites, which combine the bioactivity and biocompatibility of HA and the excellent mechanical performance of PA6, have emerged as new biomaterials with potential applications in the clinical setting. It has been shown that these nanocomposites show good similarity to natural bone in terms of chemistry and mechanical properties.RESULTS:In this study, highly crystallized hydroxyapatite nanorods (HANR) were used to fabricate PA6/HA nanocomposites viain situhydrolytic ring‐opening polymerization of ε‐caprolactam. The effect of the HANR on the thermal stability, crystallization behavior and hydrogen bonding of PA6 was investigated using thermogravimetric analysis, differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy, respectively. It was found that HANR can obviously increase the crystallization temperature and decrease the degree of supercooling. In addition, the thermal degeneration temperature of PA6 is also increased by the incorporation of HANR. FTIR analysis of the hydrogen bonded NH stretching vibration revealed that, with increasing HANR loading, the hydrogen bonded NH stretching band shifts to higher frequency and decreases in intensity.CONCLUSION:The thermal stability and crystallization ability of PA6 are improved considerably by the incorporation of HANR. However, the hydrogen bonding strength is weakened and the degree of ordering of hydrogen bonding is reduced by the incorporation of HANR, which can be explained by the formation of hydrogen bonds at the interface between OH groups of HANR and the NH or CO groups of PA6. Copyright © 2009 Society of Chemical Industry
Biodegradable nanofibrous membrane of zein/silk fibroin by electrospinning
Authors: Yao Chen , Li Xinsong , Song Tangying , Li Yunhui , Pu Yuepu 
Published: January 2009

AbstractBACKGROUND: Electrospinning of natural polymers offers a promising approach to generate nanofibers with a similar fibrillar structure to that of native extracellular matrix. In the present work, zein/silk fibroin (SF) blends were electrospun with formic acid as solvent to fabricate bicomponent nanofibrous scaffolds for biomedical applications.RESULTS: The zein/SF electrospun nanofibers had a smaller diameter and narrower diameter distribution than pure zein nanofibers, and the average diameter gradually decreased from 265 to 230 nm with increasing SF content in the blend. The predominant presence of α‐helix zein structure and random coil form of silk I in blend fibrous membranes was confirmed from Fourier transform infrared spectral and wide‐angle X‐ray diffraction data, while conversion to the β‐sheet structure of SF was also detected. The tensile strength of the zein/SF fibrous membranes was improved as the content of SF in the blend fibers increased. A preliminary study of in vitro degradation and cytotoxicity evaluated by MTT assay indicated that biodegradable zein/SF fibrous membranes did not induce cytotoxic effects in an L929 mouse fibroblast system.CONCLUSION: Biodegradable zein/SF fibrous membranes with good mechanical properties and cytocompatibility combine the beneficial characteristics of the individual components and may be useful for biomedical applications. Copyright © 2009 Society of Chemical Industry
A general strategy for highly efficient nanoparticle dispersing agents based on hybrid dendritic linear block copolymers
Authors: Vestberg Robert , Piekarski Ashley M. , Pressly Eric D. , Van Berkel Kim Y. , Malkoch Michael , Gerbac Jeffrey , Ueno Nobuhiko , Hawker Craig J. 
Published: January 2009

AbstractA modular approach to the synthesis of a library of hybrid dendritic‐linear copolymers was developed based on RAFT polymerization from monodisperse dendritic macroRAFT agents. By accurately controlling the molecular weight of the linear block, generation number of the dendrimer and the nature of the dendritic chains ends, the performance of these hybrid block copolymers as dispersing agents was optimized for a range of nanoparticles. For titanium dioxide nanoparticles, dispersion in a poly(methyl methacrylate) matrix was maximized with a second generation dendrimer containing four carboxylic acid end groups, and the quality of dispersion was observed to be superior to commercial dispersing agents for TiO2. This approach also allowed novel hybrid dendritic‐linear dispersing agents to be prepared for the dispersion of Au and CdSe nanoparticles based on disulphide and phosphine oxide end groups, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1237–1258, 2009
PCPP derivatives containing carbazole pendant as hole transporting moiety for efficient blue electroluminescence
Authors: Kim Jinwoo , Jin Youngeup , Kim Jaehong , Jung Jaeyeon , Kim Sun Hee , Lee Kwanghee , Suh Hongsuk 
Published: January 2009

AbstractThe syntheses and characterization of poly((2,6‐(4,4‐bis(4‐((2‐ethylhexyl)oxy)phenyl)‐4H‐cyclopenta[def]phenanthrene))‐co‐(2,6‐(4,4‐bis(4‐(((9‐carbazolyl)hexyl)oxy)phenyl))‐4H‐cyclopenta[def]phenanthrene)) (BCzPh‐PCPPs) and poly((2,6‐(4,4‐bis(4‐((2‐ethylhexyl)oxy)phenyl)‐4H‐cyclopenta[def]phenanthrene))‐co‐(2,6‐(4‐(4‐(((9‐carbazolyl)hexyl)oxy)phenyl)‐4‐(4‐((2‐ethylhexyl)oxy)phenyl)‐4H‐cyclopenta[def]phenanthrene))) (CzPh‐PCPPs), with carbazole unit as pendants, are presented. The carbazole moiety, which can improve the hole injection ability, was introduced as a pendant on the PCPP backbone. The devices of the polymers with the configurations of ITO/PEDOT:PSS/polymers/Ca/Al generate EL emission with maximum peaks at 400–450 nm, CIE coordinates of (x = 0.11–0.29, y = 0.11–0.33), low turn‐on voltages of 4–6 V, maximum brightness of 60–810 cd/m2, and luminescence efficiencies of 0.04–0.22 cd/A. The PL spectra of CzPh‐PCPPs films did not show any peak at around 550 nm, which corresponds to keto defect or aggregate/excimer formation, even after annealing for 30 h at 150 °C in air. Out of the series, CzPh‐PCPP1 (PCPP derivative with 10% of carbazole moiety as pendant) shows blue emission with the maximum brightness of 810 cd/m2 at 9 V, and the highest luminescence efficiency of 0.22 cd/A at 395 mA/cm2. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1327–1342, 2009
Mn2(CO)10‐induced controlled/living radical copolymerization of vinyl acetate and methyl acrylate: Spontaneous formation of block copolymers consisting of gradient and homopolymer segments
Authors: Koumura Kazuhiko , Satoh Kotaro , Kamigaito Masami 
Published: January 2009

AbstractThe controlled/living radical polymerization of vinyl acetate (VAc) and its copolymerization with methyl acrylate (MA) were investigated in bulk or fluoroalcohols using manganese complex [Mn2(CO)10] in conjunction with an alkyl iodide (RI) as an initiator under weak visible light. The manganese complex induced the controlled/living radical polymerization of VAc even in the fluoroalcohols without any loss of activity. The RI/Mn2(CO)10 system was also effective for the copolymerization of MA and VAc, in which MA was consumed faster than VAc, and then the remaining VAc was continuously and quantitatively consumed after the complete consumption of MA. The 1H and 13C NMR analyses revealed that the obtained products are block copolymers consisting of gradient MA/VAc segments, in which the VAc content gradually increases, and homopoly(VAc). The use of fluoroalcohols as solvents increased the copolymerization rate, controllability of the molecular weights, and copolymerizability of VAc. The saponification of the VAc units in poly(MA‐grad‐VAc)‐block‐poly(VAc) resulted in the corresponding poly(MA‐co‐γ‐lactone)‐block‐poly(vinyl alcohol) due to the intramolecular cyclization between the hydroxyl and neighboring carboxyl groups in the gradient segments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1343–1353, 2009
Growth of lightly crosslinked PHEMA brushes and capsule formation using pickering emulsion interface‐initiated ATRP
Authors: Chen Yunhua , Wang Chaoyang , Chen Jianxin , Liu Xinxing , Tong Zhen 
Published: January 2009

AbstractIn this work, growth of lightly crosslinked poly(2‐hydroxyethyl methacrylate) (PHEMA) brushes and subsequent capsule formation using Pickering emulsion interface‐initiated atom transfer radical polymerization (PEII‐ATRP) were investigated. Initiator‐immobilized silica nanoparticles (2.5 initiators/nm2) assembled at the interface of paraffin oil‐in‐water emulsions and ultimately stable Pickering emulsions were formed. PEII‐ATRP was conducted in the water phase of Pickering emulsions from the part of the surfaces of initiator‐immobilized silica nanoparticles exposed to water by using copper(I) chloride/bipyridine as catalyst at 35 °C. As PHEMA has a character of lightly crosslinking when the polymerization occurs in water, novel hybrid capsules (“colloidosomes”) can be obtained and were observed by confocal laser scanning microscope (CLSM) and optical microscopy (OM). The semipermeability of the resultant hollow capsules was demonstrated by the diffusion of 1‐phenylazo‐2‐naphthol. Meanwhile, the conformation of PHEMA chains can be varied in different solvents, which affects the semipermeability of these hybrid hollow capsules. We expect these hollow capsules can be further utilized to develop microdevices for drugs or cells delivery. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1354–1367, 2009
Linking polythiophene chains with vinylene‐bridges: A way to improve charge transport in polymer field‐effect transistors
Authors: Lu Kun , Sun Xiangnan , Liu Yunqi , Di Chongan , Xi Hongxia , Yu Gui , Gao Xike , Du Chunyan 
Published: January 2009

AbstractA series of novel branched polythiophene derivatives bearing different densities of vinylene‐bridges as linking chains were synthesized by a general synthetic strategy. The organic field‐effect transistors, which were fabricated by spin‐coating the polymer solutions onto octadecyltrichlorosilane‐modified SiO2/Si substrates with top‐contact configuration, afforded a high mobility of 8.0 × 10−3 cm2 V−1 s−1 with an on/off ratio greater than 104 and a threshold voltage of about −3 V in saturation regime. The devices based on these polymers possessed better performance than those of polymers without conjugated bridges and polymers with longer conjugated bridges. These results demonstrated that the combination of conjugated polythiophene backbones and vinylene‐bridges would improve the carrier mobility. As an emerging class of conjugated materials, polymers with vinylene‐bridges as linking chains would open up new opportunities in organic electronics, and their applications in organic electronics are promising. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1381–1392, 2009
Free radical copolymerization of α‐fluoroacrylates for optical materials: Synthesis and characterization
Authors: Cracowski Jean‐Marc , Montembault Véronique , Bosc Dominique , Améduri Bruno , Odobel Fabrice , Fontaine Laurent 
Published: January 2009

AbstractCopolymers based on 2,2,2‐trifluoroethyl α‐fluoroacrylate (FATRIFE) and 2,2,2‐trichlororoethyl α‐fluoroacrylate (FATRICE) were synthesized in good yields by radical process initiated by tert‐butyl 2,2‐dimethylperoxypropanoate. Molar composition of the obtained poly(FATRIFE‐co‐FATRICE) copolymers were assessed by means of 19F nuclear magnetic resonance spectroscopy. The reactivity ratios, ri, of both comonomers have been measured to be rFATRIFE = 0.56 ± 0.01 and rFATRICE = 0.11 ± 0.01 at 74 °C using the Kelen‐Tüdos method. Thermal and optical properties of the resulting polymers were examined. Thermogravimetric analyses showed good thermal stability, thermal decomposition occurring from 300 °C to 310 °C for all copolymers. Moreover, the glass transition temperature of copolymers varied from 113 °C to 127 °C, increasing with the molar ratio of FATRICE in the copolymers. The refractive indices were measured at 633, 1320, and 1550 nm, ranging from 1.3750 to 1.4812 at 1550 nm and were found to increase linearly with the chlorine content of the copolymer, allowing a precise control of the refractive index. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1403–1411, 2009
Poly(N,N‐dimethylacrylamide) hydrogels obtained by frontal polymerization
Authors: Caria Giuseppe , Alzari Valeria , Monticelli Orietta , Nuvoli Daniele , Kenny Josè M. , Mariani Alberto 
Published: January 2009

AbstractFrontal polymerization (FP) has been used as an alternative technique for the preparation of poly(N,N‐dimethylacrylamide) hydrogels. Samples were synthesized in bulk, water, or dimethyl sulfoxide (DMSO), and the obtained materials were characterized and compared in terms of their yield, swelling behavior, thermal properties, and morphology. It was found that their features are dependent on the presence and type of the solvent used. Samples prepared in bulk are characterized by the lowest yields and the highest front temperatures (Tmax) and velocities (Vf), whereas those synthesized in water have the highest yields and the lowest values of Tmax and Vf. No significant differences have been found in terms of Tg among the three series of samples. By contrast, the reaction conditions influenced the porous morphology of the samples and, consequently, their swelling capability in water. The swelling ratio ranges from about 670–700% for some samples prepared in water up to 3500% for a sample obtained in DMSO, thus indicating that this parameter can be properly tuned by using the most suitable FP conditions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1422–1428, 2009
Synthesis and rheology of biodegradable poly(glycolic acid) prepared by melt ring‐opening polymerization of glycolide
Authors: Gautier Estelle , Fuertes Patrick , Cassagnau Philippe , Pascault Jean‐Pierre , Fleury Etienne 
Published: January 2009

AbstractRing‐opening polymerization (ROP) of glycolide was studied in melt conditions and in the presence of two different initiators: 1‐dodecanol and 1,4‐butanediol and tin(II) 2‐ethylhexanoate as catalyst. Its subsequent polymerization provided poly(glycolic acid) with controlled molar masses ranging from 2000 to 42,000 g/mol with well‐defined structures characterized by NMR. Their thermal properties were evaluated by DSC analysis, and a glass transition temperature at infinite molar mass (Tg∞) of 44.8 °C was thus calculated. From rheological data, the critical molar mass for entanglement, Mc, was estimated to be near 11,000 g/mol. Furthermore, in situ polymerizations were also performed between the plates of the rheometer within a same temperature range from 210 to 235 °C. The variation of the storage and loss moduli during the polymerization step have been monitored by time sweep oscillatory experiments under an angular frequency ω = 10 rad/s. Finally, the development of an inverse rheological method allowed to calculate the bulk polymerization kinetics in the temperature range 200–230 °C. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1440–1449, 2009