bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Characterization of Well‐Defined Mid‐Chain Functional Macrophotoinitiators of Polystyrene by Combination of ATRP and “Click” Chemistry
Authors: Degirmenci Mustafa , Alter Selma , Genli Nasrettin 
Published: June 2011

AbstractA combination of ATRP and “click” chemistry is employed for efficient preparation of a novel well‐defined mid‐chain functional macrophotoinitiator of polystyrene. Bromo‐terminated polystyrene (PSt‐Br) is prepared by ATRP of styrene using a methyl‐2‐bromopropanoate initiator with CuBr/PMDETA. Subsequently, PSt‐Br is converted to PSt‐N3 by a simple nucleophilic substitution reaction. A dialkyne‐functionalized photoinitiator (alkyne‐PI‐alkyne) is synthesized using a dihydroxy‐functional photoinitiator and propargyl bromide. Then the “click” reaction between PSt‐N3 and alkyne‐PI‐alkyne is performed by Cu(I) catalysis. Spectroscopic studies reveal that low‐polydispersity polystyrene with the desired photoinitiator functionality in the middle of the chain (PSt‐PI‐PSt) is obtained. magnified image
Synthesis and Electrochemical Study of a Functional Ionic Polymer
Authors: Nagarale Rajaram K. , Bhattacharya Bhaskar , Jadhav Nitin A. , Singh Pramod K. 
Published: June 2011

AbstractViologen‐modified poly(vinylphosphonic acid) is synthesized by a simple EDC coupling reaction and characterized by FTIR and 1H NMR spectroscopy. Electrochemical studies of the polymer are performed in solution and on a skin‐printed electrode, the latter after making a composite with TEOS. A first redox peak is found at E0 = −0.57 V. The polymer is found to show diffusion‐confined phenomena in solution and surface‐confined phenomena on the electrode. On increasing the silica content, an increase in the resistivity of the film is found, which is reflected in an increase of the anodic‐to‐cathodic peak separation. From a plot of the current vs. the scan rate, the surface concentration of the redox‐active species is found to be 2.5 × 10−10 mol · cm2. magnified image
Fundamental theorem of hyperbolic geometry without the injectivity assumption
Authors: Yao Guowu 
Published: June 2011

AbstractLet \documentclass{article}\usepackage{amssymb,amsmath,amsthm,amscd,amsxtra}\begin{document}\pagestyle{empty}$\mathbb {H}^n$\end{document} be the n‐dimensional hyperbolic space. It is well‐known that, if \documentclass{article}\usepackage{amssymb,amsmath,amsthm,amscd,amsxtra}\begin{document}\pagestyle{empty}$f:\;\mathbb {H}^n\rightarrow \mathbb {H}^n$\end{document} is a bijection that preserves r‐dimensional hyperplanes, then f is an isometry. In this paper we make neither injectivity nor r‐hyperplane preserving assumptions on f and prove the following result:Suppose that \documentclass{article}\usepackage{amssymb,amsmath,amsthm,amscd,amsxtra}\begin{document}\pagestyle{empty}$f:\;\mathbb {H}^n\rightarrow \mathbb {H}^n$\end{document} is a surjective map and maps an r‐hyperplane into an r‐hyperplane, then f is an isometry.The Euclidean version was obtained by Chubarev and Pinelis in 1999 among other things. Our proof is essentially different from their and the similar problem arising in the spherical case is still open.
Well‐defined Biobased Segmented Polyureas Synthesis via a TBD‐catalyzed Isocyanate‐free Route
Authors: Tang Donglin , Mulder Dirk‐Jan , Noordover Bart A. J. , Koning Cor E. 
Published: June 2011

AbstractVia an isocyanate‐free route, a series of segmented polyureas (PUs) were synthesized from (potentially) renewable resources. To the best of our knowledge, the present work shows for the first time that the organic superbase guanidine 1,5,7‐triazabicyclododecene (TBD) which was originally developed as a catalyst for the ring‐opening polymerization of lactones, lactides or cyclic carbonates, is also a promising catalyst for the transurethanization between dicarbamates and diamino‐terminated poly(propylene glycol) (PPGda) providing PUs via an isocyanate‐free strategy. The renewable segmented PUs contain monodisperse hard segments (HSs). This well‐defined structure was verified by the DMTA plots of the PUs, showing a sharp glass transition, a sharp flow transition and a flat rubbery plateau. The flow and maximum use temperature (Tfl) of the PUs increases with the increasing number of urea groups in the corresponding dicarbamates. In addition, at constant HS length, the length of the soft‐segment (SS) can be changed to adjust the properties of the PU materials, enabling their application as adhesives, soft elastomers, or rigid plastics. magnified image
Diversified Applications of Chemically Modified 1,2‐Polybutadiene
Authors: Yuan Jiayin , ten Brummelhuis Niels , Junginger Mathias , Xie Zailai , Lu Yan , Taubert Andreas , Schlaad Helmut 
Published: June 2011

AbstractCommercially available 1,2‐PB was transformed into a well‐defined reactive intermediate by quantitative bromination. The brominated polymer was used as a polyfunctional macroinitiator for the cationic ring‐opening polymerization of 2‐ethyl‐2‐oxazoline to yield a water‐soluble brush polymer. Nucleophilic substitution of bromide by 1‐methyl imidazole resulted in the formation of polyelectrolyte copolymers consisting of mixed units of imidazolium, bromo, and double bond. These copolymers, which were soluble in water without forming aggregates, were used as stabilizers in the heterophase polymerization of styrene and were also studied for their ionic conducting properties. magnified image
Renewable Polyethylene Mimics Derived from Castor Oil
Authors: Türünç Oĝuz , Montero de Espinosa Lucas , Meier Michael A. R. 
Published: June 2011

AbstractAn increasing number of reports on the syntheses of carbohydrate‐ and plant oil‐based polymers has been published in ongoing efforts to produce plastic materials from renewable resources. Although many of these polymers are biodegradable and this is a desirable property for certain applications, in some cases non‐degradable polymers are needed for long‐term use purposes. Polyolefins are one of the most important classes of materials that have already taken their places in our daily life. On the other hand, their production relies on fossil resources. Therefore, within this contribution, we discuss synthetic routes toward a number of polyethylene mimics derived from fatty acids via thiol‐ene and ADMET polymerization reactions in order to establish more sustainable routes toward this important class of polymers. Two different diene monomers were thus prepared from castor oil derived platform chemicals, their polymerization via the two mentioned routes was optimized and compared to each other, and their thermal properties were investigated. magnified image
Electronic Structure Calculations for Hole‐Transporting Triphenylamine Derivatives in Polymer Light‐Emitting Diodes
Authors: Kröner Dominik , Krüger Hartmut , Thesen Manuel W. 
Published: June 2011

AbstractHole‐transporting polymers based on polyethene‐triphenylamine derivatives are investigated with respect to their UV/Vis spectra. Two substituents, N‐phenyl‐1‐naphthylamine and carbazole, are examined as their respective polymer light‐emitting diodes (PLEDs) show very different luminous efficiencies. In order to identify the origin of these phenomena electronic structure calculations based on TD‐DFT were performed using monomer models of the hole‐transporting polymers. In experiment these hole‐transporting polymers show very specific differences in their absorption and emission (fluorescence and phosphorescence) spectra. The analysis of the simulated absorption and emission spectra, the MOs as well as the ground and excited state geometries give explanations for the different optical performances of the corresponding PLEDs. magnified image
Diagnosis and treatment of complications related to deep brain stimulation hardware
Authors: Baizabal Carvallo José Fidel , Simpson Richard , Jankovic Joseph 
Published: June 2011

AbstractDeep brain stimulation is a therapeutic technique increasingly used in the treatment of a variety of neurological, psychiatric, and pain disorders. Although beneficial, it carries the immediate and long‐term risks associated with implanted hardware in the brain parenchyma and subcutaneous tissue. The most common hardware complications include electrode migrations or misplacements, wire fractures, skin erosion, infections, and device malfunction. We systematically reviewed the literature on deep brain stimulation–related complications and propose a diagnostic and therapeutic algorithm. Our aim is to provide a guide for clinicians and medical staff involved in the treatment of patients with deep brain stimulation for rapid recognition and efficient management of these complications. © 2011 Movement Disorder Society
Rainfed wheat yields under climate change in northeastern Iran
Authors: Eyshi Rezaie E. , Bannayan Mohammad 
Published: June 2011

AbstractProjecting agricultural crop, such as bread wheat, yield under future climate plays a vital role in planning for supply and demand, especially in developing countries. The objective of this study was to investigate impacts of climate change on grain yield of rainfed wheat in the Kashafrood basin situated in northeastern Iran. Climate projections of two General Circulation Models (HadCM3 and CGCM2) under two climate change scenarios (A2 and B2) were employed in this study. A statistical downscaling method was employed for developing the quantitative relationship between large‐scale atmospheric variables (predictors) and local variables (observations), also daily climatological parameters performed by the LARS‐WG5 stochastic weather generator, the Decision Support System for Agrotechnology Transfer (DSSAT) Version 4.5 adjusted to evaluate rainfed wheat performance. Results of this study represented substantial difference between GCM models and scenarios for wheat yield in the study area. The A2 scenario indicated more negative impact on wheat yield than the B2 using both GCM models. Highest increase and decrease of grain yield in comparison with the baseline belongs to the 2010–2039 period (+15%) using the HadCM3 model under the B2 scenario and the HadCM3 model under A2 in the 2040–2069 period (−50%), respectively. In general, growth period length indicated a markedly decreasing trend in both periods. There were strong relations between wheat yield and precipitation rate and growth period length in this study. Copyright © 2011 Royal Meteorological Society
Climate variability in areas of the world with high production of soya beans and corn: its relationship to crop yields
Authors: Llano María Paula , Vargas Walter , Naumann Gustavo 
Published: June 2011

AbstractAn important goal of this work is to study the variability of corn and soya bean crop yields in four countries with large production and substantial commercial trade in these commodities. This problem can be investigated in terms of the role that these two crops play in food programmes and in terms of the use of both crops for energy production. Four countries were chosen and divided into six production areas. A climatic summary was made of the annual cycles of extreme temperatures and precipitation. Their assessment in agriculture programmes was likewise summarized. It is seen that the variability range of the temperatures and precipitation are broad and different for each region. This finding indicates the high adaptability of these crops. This concept of adaptability is used to compare the coefficients for precipitation and crop yield. Results of the study show that corn crops show less year‐to‐year variability than do soya bean crops. The United States and the northern part of China are the regions that best use the rain supply with respect to crop yield. Soya bean crops show a greater year‐to‐year variability in the ratio of precipitation to crop yields. Argentina, the United States and northern China are the areas that best use the rain supply. To compare crop yields with climatic variables in the different regions, three types of regression model were used. The best fit is obtained by using the maximum temperatures and accumulated precipitation for each growth stage over the growing season. Copyright © 2011 Royal Meteorological Society
Functional pectoralis minor muscle flap transplantation for reconstruction of thumb opposition: An anatomic study and clinical applications
Authors: Zhuang Yong‐Qing , Xiong Hong‐Tao , Fu Qiang , Jiang Hao‐Li , Fu Xiao‐Kuan , Du Dong , Tong Jing , Hung Leung‐Kim 
Published: June 2011

AbstractIn this report, we present the results of an anatomic study on the dimensions of the pectoralis minor muscle and its neurovascular supply in 10 adult human cadavers, in attempt to evaluate the feasibility of microsurgical transplantation of a part of the muscle for thumb opposition reconstruction. A series of five patients consequently underwent thenar reconstruction with the pectoralis minor muscle flap from December 2004 to October 2006. The transferred muscle was reinnervated with the third lumbrical branch of the ulnar nerve. Follow‐up assessment showed that the patients recovered functional opposition of carpometacarpal joint with 24 degrees of pronation, and a muscle power with M4 to M5. All patients were satisfied with the appearance of reconstructed thenar eminence. We recommend this new technique for thenar and opposition reconstruction in patients who have severe loss of thenar muscles, injury to the median nerve, and wish to improve the appearance of thenar eminence. © 2011 Wiley‐Liss, Inc. Microsurgery, 2011.
Acrolein scavengers: Reactivity, mechanism and impact on health
Authors: Zhu Qin , Sun Zheng , Jiang Yue , Chen Feng , Wang Mingfu 
Published: June 2011

AbstractAcrolein (ACR) is an α,β‐unsaturated aldehyde that exists extensively in the environment and (thermally processed) foods. It can also be generated through endogenous metabolism. Its high electrophilicity makes this aldehyde notorious for its facile reaction with biological nucleophiles, leading to the modification of proteins/DNA and depletion of glutathione. Recent studies also have revealed its roles in disturbing various cell signing pathways in biological systems. With growing evidences of ACR's implication in human diseases, strategies to eliminate its hazardous impacts are of great importance. One of the intervention strategies is the application of reactive scavengers to directly trap ACR. Some known ACR scavengers include sulfur (thiol)‐containing and nitrogen (amino)‐containing compounds as well as the newly emerging natural polyphenols. In this review, the interactions between ACR and its scavengers are highlighted. The discussion about ACR scavengers is mainly focused on their chemical reactivity, trapping mechanisms as well as their roles extended to biological relevance. In addition to their direct trapping effect on ACR, these scavengers might possess multiple functions and offer additional benefits against ACR‐induced toxicity. A comprehensive understanding of the mechanism involved may help to establish ACR scavenging as a novel therapeutic intervention against human diseases that are associated with ACR and/or oxidative stress.
Rapid quantification of myocardial lipid content in humans using single breath‐hold 1H MRS at 3 Tesla
Authors: Rial Belen , Robson Matthew D. , Neubauer Stefan , Schneider Jürgen E. 
Published: June 2011

AbstractA rapid, proton magnetic resonance spectroscopy method to evaluate human myocardial lipid levels in a single breath‐hold at 3 T using a commercial whole‐body system is presented. During a 10 s breath‐hold, water unsuppressed and suppressed spectra were acquired by two phased array coils using a short‐echo time spectroscopic stimulated echo (STEAM) sequence electrocardiogram‐triggered to mid‐diastole. Lipid‐to‐water ratios were obtained in the septum of 15 healthy volunteers, (0.46 ± 0.19)%. These results agreed well with ratios obtained from averaged spectra acquired in seven multiple breath‐holds, (0.45 ± 0.20)%, providing increased signal‐to‐noise ratio but requiring longer acquisition times. Excellent correlation was found between the two methods (r = 0.94, P < 0.05). Reproducibility of 1H MRS for measuring myocardial lipid levels in a short breath‐hold was acceptable in five repeated measurements within the same subject (coefficient of variation = 19%). Thus, single breath‐hold proton spectroscopy allows reliable and quick quantification of myocardial lipids at 3 T. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Parallel imaging with asymmetric acceleration to reduce Gibbs artifacts and to increase signal‐to‐noise ratio of the gradient echo echo‐planar imaging sequence for functional MRI
Authors: Jung Kwan‐Jin , Zhao Tiejun 
Published: June 2011

AbstractParallel imaging with accelerated acquisition was noted to pronounce Gibbs artifacts which appear as ripples propagated in the phase‐encoding (PE) direction near the susceptibility‐affected region in echo‐planar imaging (EPI). Using the extended EPI sequence, which collected extended readouts outside the regular data sampling time, the pronounced Gibbs artifact was analyzed and found to be caused by an increased echo shift in the pre‐echo time (TE) of accelerated parallel imaging. This was also confirmed by theoretical derivation of the echo shift caused by the inplane susceptibility gradient in the PE direction (ISGPE). A new EPI sequence was developed to reduce the Gibbs artifact and to restore the signal level toward that of nonaccelerated parallel imaging by asymmetrically accelerating only the post‐TE sampling time and by using the extended EPI in the pre‐TE. The nonaccelerated portion in the pre‐TE used the delay for the optimum blood oxygen level dependent (BOLD) sensitivity at 3 T, maintaining the same slice coverage as the symmetrical acceleration in both pre‐TE and post‐TE. The increased data sampling points resulted in an increase of the signal‐to‐noise ratio (SNR). The restored signal and enhanced SNR of the proposed method were confirmed to deliver a better BOLD functional MRI (fMRI) result in the breath holding experiment. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
In vivo iron quantification in collagenase‐induced microbleeds in rat brain
Authors: McAuley Grant , Schrag Matthew , Barnes Samuel , Obenaus Andre , Dickson April , Kirsch Wolff 
Published: June 2011

AbstractBrain microbleeds (BMB) are associated with chronic and acute cerebrovascular disease. Because BMB present in the brain is a source of potentially cytotoxic iron proportional to the volume of extravasated blood, BMB iron content is a potentially valuable biomarker both to assess tissue risk and small cerebral vessel health. We recently reported methods to quantify focal iron sources using phase images that were tested in phantoms and BMB in postmortem tissue. In this study, we applied our methods to small hemorrhagic lesions induced in the in vivo rat brain using bacterial collagenase. As expected by theory, measurements of geometric features in phase images correlated with lesion iron content measured by graphite furnace atomic absorption spectrometry. Iron content estimation following BMB in an in vivo rodent model could shed light on the role and temporal evolution of iron‐mediated tissue damage and efficacy of potential treatments in cerebrovascular diseases associated with BMB. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
A hybrid method for more efficient channel‐by‐channel reconstruction with many channels
Authors: Huang Feng , Lin Wei , Duensing George R. , Reykowski Arne 
Published: June 2011

AbstractIn MRI, imaging using receiving coil arrays with a large number of elements is an area of growing interest. With increasing channel numbers for parallel acquisition, longer reconstruction times have become a significant concern. Channel reduction techniques have been proposed to reduce the processing time of channel‐by‐channel reconstruction algorithms. In this article, two schemes are combined to enable faster and more accurate reconstruction than existing channel reduction techniques. One scheme use two stages of channel reduction instead of one. The other scheme is to incorporate all acquired data into the final reconstruction. The combination of these two schemes is called flexible virtual coil. Applications of flexible virtual coil for partially parallel imaging, motion compensation, and compressed sensing are presented as specific examples. Theoretical analysis and experimental results demonstrate that the proposed method has a major impact in reducing computation cost in reconstruction with high‐channel count coil elements. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Exogenously administered bombesin and gastrin releasing peptide contract the female rat urethra in vivo and in vitro
Authors: Radziszewski P. , Crayton R. , Persson K. , Andersson K.‐E. , Mattiasson A. 
Published: June 2011

AbstractBackgroundBombesin (BOM) and gastrin releasing peptide (GRP) have been located to the lower urinary tract (LUT). However, there is a paucity of data demonstrating the impact of these endogenous peptides.ObjectivesThe aim of the present study was to investigate the contractile actions of BOM and GRP on the female rat urethra in vitro and in vivo. Female Sprague–Dawley rats (n = 37) weighing approximately 225 g were used. Intraurethral pressure was recorded by a catheter placed at the maximum pressure zone corresponding to the intrinsic urethral sphincter.MeasurementsIn vitro, changes in intraurethral pressure was conducted on perfused intact urethral/bladder preparations and are expressed as percentages of sphincteric intraurethral pressure achieved with noradrenaline. In vivo, changes in intraurethral pressure was conducted in anesthetized subjects and compared with the baseline intraurethral pressure and sham controls.ResultsIn vitro, the increase in intraurethral pressure induced by BOM was 23.6 ± 3.2 cmH2O, exceeding the pressure evoked with NA by 9.6 cmH2O or 174.4% whereas GRP induced a maximum pressure of 10.7 ± 1.6 cmH2O, an increase of 2.2 ± 0.5 cmH2O or 82.9% (P < 0.05) of the NA evoked pressure. In vivo, the mean baseline pressure was 22.9 ± 1.4 cmH2O. The intraurethral pressure evoked by BOM was 50.6 ± 6.3 cmH2O (P < 0.05), and for GRP, the evoked intraurethral pressure was 56.2 ± 13.4 cmH2O (P < 0.05).ConclusionsThe present data suggest that both BOM and GRP may contribute to the control of continence by their contractile action on the sphincters of the LUT outflow region. Neurourol. Urodynam. 30:1388–1391, 2011. © 2011 Wiley‐Liss, Inc.