bluuebunny/crossref_metadata_2025_split huggingface dataset:
The concordance of MRI and quantitative autoradiography estimates of the transvascular transfer rate constant of albumin in a rat brain tumor model
Authors: Paudyal Ramesh , Ewing James R. , Nagaraja Tavarekere N. , Bagher‐Ebadian Hassan , Knight Robert A. , Panda Swayamprava , Lu Mei , Ledbetter Karyn , Fenstermacher Joseph D. 
Published: May 2011

AbstractThe apparent forward transfer constant, K, for albumin was measured in 9L cerebral tumors in 15 rats. An MRI study using gadolinium‐labeled bovine serum albumin was followed by terminal quantitative autoradiography (QAR) using radioiodinated serum albumin. Look‐Locker MRI estimates of T1 followed gadolinium‐labeled bovine serum albumin blood and tissue concentration. QAR and MRI maps of K were coregistered, a region of interest (ROI) that included the tumor and its surround was selected, and the two estimates of K from the ROI on QAR and MRI maps were compared by either mean per animal ROI or on pixel‐by‐pixel data using a generalized estimating equation. An ROI analysis showed a moderate correlation between the two measures (r = 0.57, P = 0.026); pixel‐by‐pixel generalized estimating equation analysis concurred (r = 0.54, P < 0.0001). The estimates of QAR with MRI of last time points (e.g., 25 min) showed a moderate correlation (ROI r = 0.55, P < 0.035; generalized estimating equation r = 0.58, P < 0.0001). Differences between the QAR and MRI estimates of K did not differ from zero, but the MRI 25‐min estimate was significantly lower than the QAR estimate. Thus, noninvasive MRI estimates of vascular permeability can serve as a surrogate for QAR measures. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
Quantitative analysis of transmural gradients in myocardial perfusion magnetic resonance images
Authors: Hautvast G. L. T. F. , Chiribiri A. , Lockie T. , Breeuwer M. , Nagel E. , Plein S. 
Published: May 2011

AbstractConventional quantitative assessments of myocardial perfusion analyze the temporal relation between the arterial input function and the myocardial signal intensity curves, thereby neglecting the important spatial relation between the myocardial signal intensity curves. The new method presented in this article enables characterization of sub‐endocardial to sub‐epicardial gradients in myocardial perfusion based on a two dimensional, “gradientogram” representation, which displays the evolution of the transmural gradient in myocardial contrast uptake over time in all circumferential positions of the acquired images. Moreover, based on segmentation in these gradientograms, several new measurements that characterize transmural myocardial perfusion distribution over time are defined. In application to clinical image data, the new two‐dimensional representations, as well as the newly defined measurements revealed a clear distinction between normal perfusion and inducible ischaemia. Thus, the new measurements may serve as diagnostic markers for the detection and characterization of epicardial coronary and microvascular disease. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
Toward individualized SAR models and in vivo validation
Authors: Homann H. , Börnert P. , Eggers H. , Nehrke K. , Dössel O. , Graesslin I. 
Published: May 2011

AbstractThe specific absorption rate (SAR) is a limiting constraint in sequence design for high‐field MRI. SAR estimation is typically performed by numerical simulations using generic human body models. This entails an intrinsic uncertainty in present SAR prediction. This study first investigates the required detail of human body models in terms of spatial resolution and the number of soft tissue classes required, based on finite‐differences time‐domain simulations of a 3 T body coil. The numerical results indicate that a resolution of 5 mm is sufficient for local SAR estimation. Moreover, a differentiation between fatty tissues, water‐rich tissues, and the lungs was found to be essential to represent eddy current paths inside the human body. This study then proposes a novel approach for generating individualized body models from whole‐body water‐fat‐separated MR data and applies it to volunteers. The SAR hotspots consistently occurred in the arms due to proximity to the body coil as well as in narrow regions of the muscles. An initial in vivo validation of the simulated fields in comparison with measured B1‐field maps showed good qualitative and quantitative agreement. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
Assessment of early diastolic strain‐velocity temporal relationships using spatial modulation of magnetization with polarity alternating velocity encoding (SPAMM‐PAV)
Authors: Zhang Ziheng , Dione Donald P. , Brown Peter B. , Shapiro Erik M. , Sinusas Albert J. , Sampath Smita 
Published: May 2011

AbstractA novel MR imaging technique, spatial modulation of magnetization with polarity alternating velocity encoding (SPAMM‐PAV), is presented to simultaneously examine the left ventricular early diastolic temporal relationships between myocardial deformation and intra‐cavity hemodynamics with a high temporal resolution of 14 ms. This approach is initially evaluated in a dynamic flow and tissue mimicking phantom. A comparison of regional longitudinal strains and intra‐cavity pressure differences (integration of computed in‐plane pressure gradients within a selected region) in relation to mitral valve inflow velocities is performed in eight normal volunteers. Our results demonstrate that apical regions have higher strain rates (0.145 ± 0.005 %/ms) during the acceleration period of rapid filling compared to mid‐ventricular (0.114 ± 0.007 %/ms) and basal regions (0.088 ± 0.009 %/ms), and apical strain curves plateau at peak mitral inflow velocity. This pattern is reversed during the deceleration period, when the strain‐rates in the basal regions are the highest (0.027 ± 0.003 %/ms) due to ongoing basal stretching. A positive base‐to‐apex gradient in peak pressure difference is observed during acceleration, followed by a negative base‐to‐apex gradient during deceleration. These studies shed insight into the regional volumetric and pressure difference changes in the left ventricle during early diastolic filling. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Myocardial BOLD imaging at 3 T using quantitative T2: Application in a myocardial infarct model
Authors: Ghugre Nilesh R. , Ramanan Venkat , Pop Mihaela , Yang Yuesong , Barry Jennifer , Qiang Beiping , Connelly Kim A. , Dick Alexander J. , Wright Graham A. 
Published: May 2011

AbstractLeft ventricular remodeling as a result of acute myocardial infarction (AMI) is associated with significant morbidity, leading to cardiovascular dysfunction, disability, and death. Despite successful revascularization, coronary vasodilatory dysfunction has been shown in infarcted and remote myocardium of patients following AMI. Our study explored the utility of a T2‐based blood‐oxygen‐level‐dependent approach in probing regional and longitudinal fluctuations in vasodilatory function in a porcine model of AMI at 3 T. Ten pigs underwent MRI in control state and at day 2, weeks 1–6 following 90 min occlusion followed by reperfusion. The remote myocardium exhibited vasodilatory dysfunction at weeks 1 and 2 that gradually recovered, whereas the infarct zone showed no vasodilatory alterations. Our study suggests that microvascular alterations occurring in infarcted and remote myocardium after AMI might serve as an indicator of adverse left ventricular remodeling. The blood‐oxygen‐level‐dependent technique using quantitative T2 could potentially be a useful noninvasive tool to evaluate novel therapeutic strategies aimed at limiting vasoconstriction and improving coronary flow reserve after AMI. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
An approach to variable time receding horizon control
Authors: Kowalska Kaska , von Mohrenschildt Martin 
Published: May 2011

SUMMARYThis paper proposes a method for the design of a predictive controller with variable step sizes. Instead of using a fixed sampling frequency, the switching times are incorporated into an optimization problem, thus resulting in an adaptive step‐size control process. The controller with the variable time steps is shown to require less tuning and reduces the number of expensive model evaluations. An alternate solution approach had to be implemented to accommodate the new formulation. Stability is proven in a context that does not require terminal cost or constraints. Copyright © 2011 John Wiley & Sons, Ltd.
Combination testing (Stage 2) of the Anti‐IGF‐1 receptor antibody IMC‐A12 with rapamycin by the pediatric preclinical testing program
Authors: Kolb E. Anders , Gorlick Richard , Maris John M. , Keir Stephen T. , Morton Christopher L. , Wu Jianrong , Wozniak Amy W. , Smith Malcolm A. , Houghton Peter J. 
Published: May 2011

AbstractBackgroundIMC‐A12, a fully human antibody that blocks ligand binding to the Type 1 insulin‐like growth factor receptor, and rapamycin, a selective inhibitor of mTORC1 signaling, have both demonstrated significant antitumor activity against PPTP solid tumor models. Here we have evaluated antitumor activity of each agent individually and in combination against nine tumor models.ProceduresIMC‐A12 was administered twice weekly and rapamycin was administered daily for 5 days per week for a planned 4 weeks. The impact of combining IMC‐A12 with rapamycin was evaluated using two measures: (1) the “therapeutic enhancement” measure, and (2) a linear regression model for time‐to‐event to formally evaluate for sub‐ and supra‐additivity for the combination compared to the agents used alone.ResultsTwo osteosarcomas, and one Ewing sarcoma of the nine xenografts tested showed therapeutic enhancement. The combination effect was most dramatic for EW‐5 for which PD2 responses of short duration were observed for both single agents and a prolonged PR response was observed for the combination. Both OS‐2 and OS‐9 showed significantly longer times to progression with the combination compared to either of the single agents, although objective response criteria were not met.ConclusionsThe combination of IMC‐A12 with rapamycin was well tolerated, and induced tumor responses that were superior to either single agent alone in several models. These studies confirm reports using other antibodies that inhibit IGF‐1 receptor‐mediated signaling that indicate enhanced therapeutic effect for this combination, and extend the range of histotypes to encompass additional tumors expressing IGF‐1R where this approach may be effective. Pediatr Blood Cancer 2012; 58: 729–735. © 2011 Wiley Periodicals, Inc.
Effect of clay dispersion on the cell structure of LDPE/clay nanocomposite foams
Authors: Seraji S.M. , Razavi Aghjeh M.K. , Davari M. , Salami Hosseini M. , Khelgati Sh. 
Published: May 2011

AbstractIn this study, the effect of clay and its dispersion state on the cell morphology and foaming behavior of chemically crosslinked polyethylene (PE) foams were examined. In addition, the effect of foaming process on the clay morphology was also considered. It was shown that the morphology of the clay before the foaming process and its compatibility with PE matrix play a major role in determining the final foam properties. A PE‐g‐MA compatibilizer was used to increase the melt intercalation of PE onto the clay galleries and to improve clay dispersion in the PE matrix. The uniform dispersion of clay provided greater and well‐ dispersed nucleation sites. This led to smaller cell size, narrower cell size distribution, and higher cell density, and lower foam density. During the foaming process, intercalated clays were delaminated due to the rapid polymer melt expansion that inhibited gas release and increased foam expansion ratio. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Synthesis and properties of fluorene‐based polyimide adhesives
Authors: An Hao‐Yuan , Zhan Mao‐Sheng , Wang Kai 
Published: May 2011

AbstractFive kinds of fluorene‐based polyimides (PIs) based on 4,4′‐oxydiphthalicanhydride (ODPA), 9,9′‐bis(4‐aminophenyl)fluorene (BAFL), and 3,4′‐diaminodiphenyl ether (3,4′‐ODA) were synthesized through two‐step method. The partially or fully imidized PI films were cast from poly(amic acid) (PAA) solution and were imidized by far‐infrared radiation at various temperatures. The degree of imidization was characterized by FT‐IR and TGA. The fully imidized PI films were characterized by DMTA, TGA, and tensile tests. The partially imidized PI films were adhered to stainless steel plates for preparing the single lap joints. Lap shear strength (LSS) at room temperature was measured to compare the adhesive strength of single lap joint. Fractured surfaces were analyzed using scanning electron microscopy (SEM). The effects of fluorene content on thermal, tensile, and adhesion properties of PIs were elaborately studied. The results showed that PI films exhibited high glass transition temperature (Tg), good thermalplasticity, and thermal stability. The LSS of PIs increased abruptly with the incorporation of fluorene groups. The LSS of PI‐50/50 was the highest, which was 22.3 MPa. The LSS of PI‐50/50 was also measured at high temperature to investigate the thermal resistance of fluorene‐based PI adhesive. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.
Synthesis and properties of a novel bismaleimide resin containing 1,3,4‐oxadiazole moiety and the blend systems thereof with epoxy resin
Authors: Xiong Xuhai , Chen Ping , Zhu Nengbo , Yu Qi , Zhang Jinxiang , Wang Baichen 
Published: May 2011

AbstractA new bismaleimide monomer, 2‐((4‐maleimidophenoxy)methyl)‐5‐(4‐maleimidophenyl)‐1,3,4‐oxadiazole (Mioxd), was designed and synthesized. The chemical structure of the monomer was confirmed by means of Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy and elemental analysis, and its thermal properties were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mioxd as a reactive modifier was blended with epoxy resin based on bisphenol A diglycidyl ether (DGEBA) in weight ratio of 5, 10, and 15%, using 4,4′‐diaminodiphenyl sulfone (DDS) as hardener. The effect of Mioxd addition on the cure behavior and thermal properties of the blend resins was studied by DSC, TGA, and dynamic mechanical analysis (DMA). DSC investigations showed that the main exothermic peak temperature (Tp) of the blend systems did not obviously shift with increasing Mioxd content whereas a new shoulder appeared and gradually grew on the high temperature side of the exothermic peak. The results of DMA measurements exhibited the glassy storage modulus (G') and glass transition temperatures (Tg) increased as the Mioxd content was increased, the cured blends investigated were miscible and no phase separation occurred. Further, the thermal decomposition temperature first decreased and then increased, but the char yield at 600°C increased with an increase in Mioxd content. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Dispersion of multiwall carbon nanotubes in blends of polypropylene and acrylonitrile butadiene styrene
Authors: Khare Rupesh A. , Bhattacharyya Arup R. , Panwar Ajay S. , Bose Suryasarathi , Kulkarni Ajit R. 
Published: May 2011

AbstractState of dispersion of purified multiwall carbon nanotubes (p‐MWNT) in the presence of neutralized MWNT (n‐MWNT) in aqueous solution was assessed through UV–Visible spectroscopy, dynamic light scattering measurements, and solution experiments. Raman spectroscopic analysis revealed that debundling of p‐MWNT in the presence of n‐MWNT in aqueous solution was persistent even in the solid mixture, which was supported by transmission electron microscopic analysis. The proposed mechanism behind the improved dispersion of p‐MWNT in the presence of n‐MWNT in aqueous solution has been based on the electrostatic charge repulsion between negatively charged n‐MWNT. The state of dispersion of p‐MWNT in the presence of n‐MWNT in 45/55 polypropylene/acrylonitrile butadiene styrene (PP/ABS) blends was assessed through Raman spectroscopic analysis, bulk electrical conductivity measurements, solution experiment, and crystallization studies. Raman spectroscopic analysis indicated that the state of dispersion of MWNT was improved with increasing n‐MWNT content of the mixture. This strategy led to a remarkable increase in the bulk electrical conductivity of 45/55 PP/ABS blends at 3 wt% MWNT content and was strongly dependent on the concentration of n‐MWNT in the mixture. Differential scanning calorimetric measurements along with solution experiments revealed the subsequent migration of MWNT from the PP phase to the ABS phase in the blends during melt‐mixing in the presence of higher fraction of n‐MWNT. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Kinetics of the anionic polymerization of ε‐caprolactam from an isocyanate bearing polystyrene
Authors: Zhang Cai‐Liang , Feng Lian‐Fang , Gu Xue‐Ping , Hoppe Sandrine , Hu Guo‐Hua 
Published: May 2011

AbstractThis work aims to systematically study a reactive extrusion process for the synthesis of graft copolymers with polystyrene (PS) as backbone and polyamide 6 (PA6) as grafts. The underlying chemistry relies on the use of a random copolymer of styrene (St) and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI), PS‐co‐TMI, to activate the polymerization of ε‐caprolactam (CL) using sodium ε‐caprolactam (NaCL) as a catalyst. To obtain sufficiently high polymerization rate and monomer conversion, the following conditions should be met simultaneously: polymerization temperature higher than 220°C, TMI content in PS‐co‐TMI higher than 2 wt%, and the molar ratio between the isocyanate group in PS‐co‐TMI and NaCL smaller than 3. Moreover, feeding mode has a little effect on the CL conversion and the composition of PS‐g‐PA6 but has a strong effect on the polymerization induction time. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Novel foam injection molding technology using carbon dioxide‐laden pellets
Authors: Lee Jungjoo , Turng Lih‐Sheng , Dougherty Eugene , Gorton Patrick 
Published: May 2011

AbstractInjection molding of foamed components typically uses chemical blowing agents (CBAs) or physical blowing agents (PBAs) to produce a cellular or microcellular structure. A CBA can be easily and directly mixed with plastic pellets and fed into the molding machine through the hopper while a generally finer, microcellular structure can be realized using PBAs. The PBA route is accomplished by injecting more environmentally benign gases into the machine barrel to form a single‐phase polymer–gas solution that subsequently foams during molding. This article proposes a new foam injection molding technology that enables the ease of processing of the CBA method with the foaming characteristics of a PBA, but in a cost‐effective fashion. In this article, the manufacturing method and theoretical background for producing plastic pellets loaded with carbon dioxide as well as the resulting part characteristics are described. Using the proposed technique, lightweight injection molded parts with a cellular structure, good dimensional stability, and a good surface quality can be produced. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Styrene‐assisted grafting of maleic anhydride onto isotactic poly butene‐1
Authors: Zhao Yongxian , Ma Yujie , Yao Wei , Huang Baochen 
Published: May 2011

AbstractGrafting of maleic anhydride (MAH) onto isotactic poly butene‐1 (iPB‐1) was carried out by thermal decomposition of dicumyl peroxide (DCP) using electron‐donating monomer styrene (St), and were carried out in the molten state in a twin‐screw extruder according to an experimental design in which the content of MAH and St were varied. The calibration curve was constructed from FTIR measurements and titration which can obtain the absolute amounts of grafted MAH according to FTIR data. The proposed mechanism was that when St is added to the iPB‐1/MAH/peroxide grafting system, St reacted first with MAH to form a charge‐transfer complex (CTC). Then CTC react (or copolymerize) with macroradicals. The grafting of MAH onto iPB‐1 (iPB‐1‐MAH) accelerated crystalline transformation rate of form II to I. The contact angle decreased with the increase of grafting degree, which indicated that surface polarity increased. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Preparation of neutrally colorless, transparent polynorbornenes with multiple redox‐active chromophores via ring‐opening metathesis polymerization toward electrochromic applications
Authors: Lian Wei‐Ren , Wang Kun‐Li , Jiang Jyh‐Chiang , Liaw Der‐Jang , Lee Kueir‐Rarn , Lai Juin‐Yih 
Published: May 2011

AbstractA new electrochromic norbornene derivative containing triphenylamine groups (NBDTPAC8) was synthesized using norbornene amine and bromotriphenylamine. NBDTPAC8 was used in ring‐opening metathesis polymerization to obtain poly(NBDTPAC8) using different Grubbs' catalysts and followed by hydrogen reduction to obtain poly(HNBDTPAC8). The glass transition temperatures (Tg) of poly(NBDTPAC8) and hydrogenated poly(HNBDTPAC8) were 132 and 89 °C, respectively. Poly(HNBDTPAC8) film exhibited a fluorescence maximum around 416 nm with a quantum yield of up to 60%. Hydrogenated poly(HNBDTPAC8) film showed excellent transparency (up to 93%). Poly(HNBDTPAC8) showed cyclic voltammetric and electrochromic behaviors similar to those of poly(NBDTPAC8). The cyclic voltammogram of a poly(HNBDTPAC8) film cast onto an indium tin oxide (ITO)‐coated glass substrate exhibited three reversible oxidation redox couples at 0.69, 0.94 and 1.38 V versus Ag/Ag+ in an acetonitrile solution. The electrochromic characteristics of poly(HNBDTPAC8) showed excellent stability and reversibility, with multi‐staged color changes from its colorless neutral form to green, light blue and dark blue upon the application of potentials ranging from 0 to 1.60 V. The color switching time and bleaching time of the poly(HNBDTPAC8) film were 6.2 s and 4.3 s at 1175 nm and 6.6 s and 4.4 s at 970 nm, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.
Synthesis and applications of cyano‐vinylene‐based polymers containing cyclopentadithiophene and dithienosilole units for photovoltaic cells
Authors: Padhy Harihara , Sahu Duryodhan , Patra Dhananjaya , Pola Murali Krishna , Huang Jen‐Hsien , Chu Chih‐Wei , Wei Kung‐Hwa , Lin Hong‐Cheu 
Published: May 2011

AbstractTwo β‐cyano‐thiophenevinylene‐based polymers containing cyclopentadithiophene (CPDT‐CN) and dithienosilole (DTS‐CN) units were synthesized via Stille coupling reaction with Pd(PPh3)4 as a catalyst. The effects of the bridged atoms (C and Si) and cyano‐vinylene groups on their thermal, optical, electrochemical, charge transporting, and photovoltaic properties were investigated. Both polymers possessed the highest occupied molecular orbital (HOMO) levels of about −5.30 eV and the lowest unoccupied molecular orbital (LUMO) levels of about −3.60 eV, and covered broad absorption ranges with narrow optical band gaps (ca. 1.6 eV). The bulk heterojunction polymer solar cell (PSC) devices containing an active layer of electron‐donor polymers (CPDT‐CN and DTS‐CN) blended with an electron‐acceptor, that is, [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) or [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM), in different weight ratios were explored under 100 mW/cm2 of AM 1.5 white‐light illumination. The PSC device based on DTS‐CN:PC71BM (1:2 w/w) exhibited a best power conversion efficiency (PCE) value of 2.25% with Voc = 0.74 V, Jsc = 8.39 mA/cm2, and FF = 0.36. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.