bluuebunny/crossref_metadata_2025 huggingface dataset:
The Quaternary Lancaster Sound trough‐mouth fan, NW Baffin Bay
Authors: Li Gang , Piper David J.W. , Calvin Campbell D.
Published: May 2011

The development of the Lancaster Sound Trough Mouth Fan (TMF) and glacial history in Arctic Canada were studied using a high‐resolution seismic profile across the entire fan and two piston cores. Stacked tills separated by erosion surfaces on the shelf pass seaward through till deltas into thick transparent glacigenic debris flow (GDF) deposits on the slope, separated by thin, well‐stratified glaciomarine layers. An age model was built by ties to the Ocean Drilling Program Site 645. The deepest GDF on the seismic profile was indicative of the onset of shelf‐crossing glaciation in the Early Pleistocene. The transition of the growth of Lancaster Sound TMF from an aggradational sequence (unit M) to an aggradational–progradational sequence (unit F) occurred at the Middle Pleistocene transition in glacial cyclicity. In the most recent glacial cycle, GDF sheets were deposited during Heinrich events 4 and 2 according to the correlation of the main detrital carbonate beds in two piston cores. The outmost till wedge reflects the maximum advance of the grounding glacier, far seaward of previously proposed Last Glacial Maximum ice extent. Copyright © 2011 John Wiley & Sons, Ltd.
Weighted inequalities for the one‐sided geometric maximal operators
Authors: Salvador Pedro Ortega , Torreblanca Consuelo Ramírez
Published: May 2011

We characterize the pairs of weights (u, v) such that the one‐sided geometric maximal operator G+,  defined for functions f of one real variable by

verifies the weak‐type inequality

or the strong type inequality

for 0 < p < ∞.

We also find two new conditions which are equivalent to A+∞. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
A toenail flap based on the fibro‐osseous hiatus branch for fingernail reconstruction
Authors: Ki Sae H. , Hwang Kun , Kim Dong H. , Hwang Sejin , Han Seung H.
Published: May 2011

This study included two parts: 1) cadaver dissection to elucidate the perfusion of toenail flaps by the fibro‐osseous hiatus branch (FHB), and 2) clinical application of the toenail flap for reconstruction of a fingernail defect. Four second toes of two fresh Korean cadavers were dissected. The plantar digital artery (PDA) and terminal segment branch (TSB) were ligated, and red latex was injected distally into the ligated PDA. Perfusion of the dye into the toenail bed through the FHB was observed. From Oct 2004 to Sep 2009, eight toenail flaps based on the FHB pedicle with or without the distal phalanx and pulp were applied to seven patients for finger nail reconstruction. The toenail flap was marked at 5 mm distal to the nail fold and 5 mm lateral to the paronychium. The toenail complex based on the FHB was elevated and transferred to the finger. The nail and matrix were elevated with or without including the distal phalanx. The results of perfusion study showed that one side of the unilateral FHB was identified and traced proximal to the PDA, which was ligated. The distal toenail bed was perfused by the dye through the FHB. In clinical application, all the toenail flaps flourished and survived. We suggest that the toenail flap based on the FHB may be useful for fingernail reconstruction with minimal donor morbidity. © 2011 Wiley‐Liss, Inc. Microsurgery 2011.
Sternocleidomastoid region restoration with lateral hemisoleus muscle incorporatied in free fibular flap for reconstruction of radical neck dissection and hemimandibulectomy
Authors: Ersoy Burak , Sönmez Ahmet , Bayrami̇çli̇ Mehmet
Published: May 2011

In the treatment of head and neck carcinoma, radical cervical lymphadenectomy leaves the affected side of the neck devoid of the sternocleidomastoid muscle, thus more vulnerable to the unwanted side effects of the adjuvant radiotherapy. It also causes asymmetry and cosmetically unpleasant appearance of the cervical region. In the reported case with widely ulcerated squamous‐cell carcinoma over mandible, hemimandibulectomy and radical neck dissection was performed. Following the mandibular reconstruction, the lateral hemisoleus muscle of the harvested osteomyocutaneous fibula flap was utilized to restore the ipsilateral sternocleidomastoid region. This new application promises to be a useful method, which can aid in the restoration of the aesthetic contour of the neck and provide protection against unwanted effects of the adjuvant radiotherapy on the ipsilateral carotid artery. © 2011 Wiley‐Liss, Inc. Microsurgery 2011.
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

The 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

Conventional 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

The 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

A 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

Left 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

This 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

Background

IMC‐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.

Procedures

IMC‐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.

Results

Two 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.

Conclusions

The 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

In 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

Five 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

A 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

State 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

This 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

Injection 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

Grafting 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
Structuring of Temporary Multi-Organizations: Contingency Theory in the Building Sector
Authors: Lizarralde Gonzalo , de Blois Michel , Latunova Iskra
Published: May 2011

The appropriate management of construction projects presupposes a clear comprehension of the structure of the temporary multi-organization (TMO); however, most of the work on the structuring of TMOs has concentrated either on procurement strategies or the structure of individual organizations. Current approaches, therefore, do not fully consider the roles of all project stakeholders, the informal communications, and the complexity of the client organization. Instead, we argue that the contingency theory contributes to the understanding of the structuring of TMOs. The analysis of 27 recent construction projects allows us to identify two contingency factors and patterns of configuration of the TMO.
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

A 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

Two 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.
Competitive absorption of epoxy monomers on carbon nanotube: A molecular simulation study
Authors: Wu Chaofu
Published: May 2011

Position restrained (PR) molecular dynamics (MD) simulations were carried out on the bulk models for the two composite systems including epoxy monomers and carbon nanotube (CNT). The pair energies and the radial distribution functions (RDFs) were computed to evaluate the relative strength of the epoxy monomers binding to the CNT. It is found that the aromatic amine binds more strongly to the CNT than does the aliphatic amine. A vivid view indicates the aromatic rings tend to form π‐stacking with the CNT, and the compounds with aromatic rings prefer to wrap the CNT. These simulated results are in good agreement with those obtained previously from the vacuum models. This work demonstrates that curing agents affect the interactions between epoxy resin and CNT. Other comparisons of relative binding strength of epoxy monomers also depend upon the temperature. Further analyses suggest that the aliphatic amine exhibits more strong interactions with epoxy resin than does the aromatic amine, mainly due to the presence of hydrogen bonds (HBs) between them. Thus, the ultimate performance of epoxy‐CNT polymer nanocomposites should be affected by the two reverse interactions. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011.
Use of tumor dynamics to clarify the observed variability among biochemical recurrence nomograms for prostate cancer
Authors: Dimonte Guy , Bergstralh E.J. , Bolander M.E. , Karnes R.J. , Tindall D.J.
Published: May 2011

BACKGROUND

Nomograms for biochemical recurrence (BCR) of prostate cancer (PC) after radical prostatectomy can yield very different prognoses for individual patients. Since the nomograms are optimized on different cohorts, the variations may be due to differences in patient risk‐factor distributions. In addition, the nomograms assign different relative scores to the same PC risk factors and rarely stratify for tumor growth rate.

METHODS

We compared BCR‐free probabilities from the GPSM model with a cell kinetics (CK) model that uses the individual's tumor state and growth rate. We first created a cohort of 143 patients that reproduced the GPSM patient distribution in Gleason score, Prostate specific antigen (PSA), Seminal vesicle involvement and Margin status since they form the GPSM score. We then performed 143 CK calculations to determine BCR‐free probabilities for comparison with the GPSM results for all scores and with four other prominent nomograms for a high‐risk patient.

RESULTS

The BCR‐free probabilities from the CK model agree within 10% with those from the GPSM study for all scores once the CK model parameters are stratified in terms of the GPSM risk factors and the PSA doubling time (PSADT). However, the probabilities from widely used nomograms vary significantly.

CONCLUSIONS

The CK model reproduces the observed GPSM BCR‐free probabilities with a broad stratification of model parameters for PC risk factors and can thus be used to describe PC progression for individual patients. The analysis suggests that nomograms should stratify for PSADT to be predictive. Prostate 72:280–290, 2012. © 2011 Wiley Periodicals, Inc.
Micro‐electroluminescence of cyan InGaN‐based multiple quantum well structures
Authors: Meyer Tobias , Peter Matthias , Danhof Julia , Schwarz Ulrich T. , Hahn Berthold
Published: May 2011

Micro‐electroluminescence measurements were performed on multiple quantum well samples grown on sapphire and GaN substrates with emission wavelength 495 nm. Meandering structures were found both in intensity and peak energy. Areas with higher emission intensity had lower energy, which is a hint for carrier redistribution within the quantum wells. A comparison between atomic force microscopy and photoluminescence microscopy revealed that V‐shaped pits reside in regions with low intensity and are associated with higher emission energy. Small intensity and emission energy variations were also found in defect‐free areas and are probably caused by indium content or quantum well thickness fluctuations leading to higher carrier density in regions with low potential energy.
Different behavior of semipolar and polar InGaN/GaN quantum wells: Pressure studies of photoluminescence
Authors: Staszczak G. , Suski T. , Khachapuridze A. , Perlin P. , Funato M. , Kawakami Y.
Published: May 2011

Photoluminescence of (11–22) semipolar and (0001) polar InGaN/GaN quantum wells (QWs) was studied as a function of exciting laser intensity and hydrostatic pressure. A large photoluminescence energy shift with pressure (dEPL/dp) was observed in semipolar QWs comparing to polar ones. In addition, a negligible blue‐shift as a function of exciting laser intensity gives a strong argument for the absence of a built‐in electric field in the studied semipolar structures. These results suggest that In‐segregation effects play an important role in semipolar QWs.
Homoepitaxial growth of AlN on nitrided sapphire by LPE method using Ga–Al binary solution
Authors: Adachi Masayoshi , Maeda Kazuo , Tanaka Akikazu , Kobatake Hidekazu , Fukuyama Hiroyuki
Published: May 2011

A novel liquid phase epitaxy method was proposed for growing an AlN layer using Ga–Al binary flux under normal pressure. In this method, nitrogen gas was injected into the flux. Then a nitrided sapphire substrate was used as a template to achieve homoepitaxial growth. Advantages of using a nitrided sapphire substrate were demonstrated; the optimum flux composition was investigated. We grew 1‐µm‐thick c‐axis oriented AlN layer for 5 h at 1573 K. The full width at half maximum values of X‐ray rocking curves for AlN (0002) and (10−12) were, respectively, 50 and 590 arcsec. Moreover, the surface morphology and interfacial structure were observed using a scanning electron microscope, laser microscope, and high‐resolution transmission electron microscope.
Low leakage current in AlGaN/GaN HFETs with preflow of Mg source before growth of u‐GaN buffer layer
Authors: Oshimura Yoshinori , Sugiyama Takayuki , Takeda Kenichiro , Iwaya Motoaki , Takeuchi Tetsuya , Kamiyama Satoshi , Akasaki Isamu , Amano Hiroshi
Published: May 2011

AlGaN/GaN heterostructure field‐effect transistors were grown by metalorganic vapor phase epitaxy on Fe‐doped GaN substrates with a preflow of the Mg source. We realized a low drain leakage current, 1.05 µA/mm, at VDS = 20 V and VGS = −5 V with LGD = 3 µm. This leakage current was one order of magnitude lower than that obtained without a preflow of the Mg source. The breakdown voltage was over 250 V with LGD = 10 µm. The on resistance was estimated to be 3.6 mΩ cm2. No significant redistribution or memory effect of Mg was observed by secondary ion mass spectroscopy measurement.
Red emitting LEDs formed by indium rich quantum dots incorporated in MQWs
Authors: Soh C. B. , Liu W. , Chua S. J. , Tan Rayson J. N. , Ang S. S. , Chow S. Y.
Published: May 2011

indium rich InGaN nanostructures grown by MOCVD were incorporated in InGaN/GaN quantum wells for long wavelength emission by optimizing the growth condition for the quantum dots (QDs) and InGaN quantum wells. The indium rich InGaN QDs were about 20 nm in diameter and 1.5 nm in height with a density of ∼1 × 1010 cm−2. The InGaN nanostructures in quantum wells capped by AlN were insensitive to In out‐diffusion due to formation of stable Al‐N bonds and lower mobility of Al adatoms on the film surface at 780 °C. The piezeoelectric field in the active layers of the light emitting diodes (LEDs) was reduced with the AlN capped layer and minimal blueshift of the electroluminescence was observed as compared to conventional InGaN/GaN LEDs was noted. The energy band profile of strained AlN/InGaN/QDs/InGaN/GaN quantum well system was analyzed.
Development of high efficiency 255–355 nm AlGaN‐based light‐emitting diodes
Authors: Pernot Cyril , Fukahori Shinya , Inazu Tetsuhiko , Fujita Takehiko , Kim Myunghee , Nagasawa Yosuke , Hirano Akira , Ippommatsu Masamichi , Iwaya Motoaki , Kamiyama Satoshi , Akasaki Isamu , Amano Hiroshi
Published: May 2011

We report on the fabrication and characterization of high efficiency ultraviolet (UV) light emitting diodes (LEDs) with emission wavelength ranging from 255 to 355 nm. Epi‐layers of UV LEDs were grown on AlGaN templates with sapphire substrates. Flip‐chip configuration without removing sapphire is used for characterization of the UV LEDs. External quantum efficiencies (EQEs) over 3% were obtained for all the investigated wavelengths with maximum value reaching 5.1% for 280 nm LED. Under RT DC operation at a current of 500 mA, output powers of 38, 77, and 64 mW were measured for 257, 280, and 354 nm, respectively. By using enhanced light extraction technologies, such as, moth‐eye structure on the back side of the sapphire substrate, we expect to improve these values by up to 50%.
DNA‐sensor based on AlGaN/GaN high electron mobility transistor
Authors: Schwarz Stefan U. , Linkohr Stefanie , Lorenz Pierre , Krischok Stefan , Nakamura Takako , Cimalla Volker , Nebel Christoph E. , Ambacher Oliver
Published: May 2011

AlGaN/GaN high electron mobility transistors (HEMTs) show great promise for the realization of sensors for biomolecular, pharmaceutical and medical purposes. The high sensitivity and the stability in biological solutions are great advantages of this approach. Therefore, we created a novel HEMT‐based DNA hybridization sensor. In contrast to other comparable devices, this sensor uses a system of linker molecules to covalently bond the probe DNA to the semiconductor surface. This approach offers the possibility to adjust the density of the probe DNA and provides a highly stable connection. The device shows a clear signal when exposed to the target DNA sequence. Due to the robust attachment of the probe DNA, the double strand can be denatured without corrupting the device. Consequently, the detection of the hybridization event can be repeated several times.
Adaboosting‐based dynamic weighted combination of software reliability growth models
Authors: Li Haifeng , Zeng Min , Lu Minyan , Hu Xuan , Li Zhen
Published: May 2011

Software reliability growth models (SRGMs) are very important for software reliability estimation and prediction and have been successfully applied in the critical airborne software. However, there is no general model which can perform well for different cases. Thus, some researchers proposed to obtain more accurate estimation and prediction than one single model by combining various individual SRGMs together. AdaBoosting is a commonly used machine learning algorithm for combining several weak predictors into a single strong predictor to significantly improve the estimating and forecasting accuracy, which may be very suitable for the combination of SRGMs. Hence, two novel AdaBoosting‐based combination approaches for improving the parametric SRGMs are presented in this paper. The first one selects several variations of one original SRGM for obtaining the self‐combination model (ASCM). The second selects several various candidate SRGMs for obtaining the multi‐combinational model (AMCM). Finally, two case studies are presented and the results show that: (1) the ASCM is fairly effective and applicable for improving the estimation and prediction performance of its corresponding original SRGM without adding any other factors and assumptions; (2) the AMCM is notably effective and applicable for combining SRGMs because it has well applicability and provides a significantly better reliability estimation and prediction power than the traditional SRGMs and also yields a better estimation and prediction power than the neural‐network‐based combinational model. Copyright © 2011 John Wiley & Sons, Ltd.
Quantum chemical modeling studies of ethylbenzene dehydrogenase activity
Authors: Szaleniec Maciej , Salwiński Aleksander , Borowski Tomasz , Heider Johann , Witko Malgorzata
Published: May 2011

Quantum chemical modeling is used to predict the reactivity of ethylbenzene dehydrogenase (EBDH), a molybdenum enzyme that catalyzes the stereoselective oxidation of alkylaromatic and alkylheterocyclic hydrocarbons to the (S)‐enantiomers of secondary alcohols. The reaction mechanism is studied for four different substrates: ethylbenzene, 4‐ethylphenol, allylbenzene, and 4‐ethylpyridine with a cluster model of the active site. The modeling predicts radical CH activation followed by the formation of a radical intermediate product. Then another electron is transferred to form a carbocation species in TS2, followed by a tightly associated OH rebound step. The modeling study allows qualitative correlation of energy barriers with the results of kinetic assays and identifies factors influencing the chemical reactivity of EBDH with different substrates. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011.
CaCuO2 antiferromagnetism using shallow well added solely to atomic potential for generating O2− basis set of periodic molecular orbitals with consideration of coulomb potential in solid in an LDA
Authors: Fukushima Kimichika
Published: May 2011

The antiferromagnetism in an infinite‐layer copper oxide CaCuO2 was analyzed by adding a well potential solely to the atomic potential of an O2− ion in constructing a basis set for a Bloch‐type periodic linear combination of numerically calculated atomic orbitals. (The well is not added to the solid Hamiltonian.) In this method that solves a secular equation to find all electron states, the original Kohn−Sham local density approximation (LDA) was employed. (Magnetic properties calculated with generalized gradient approximation are more similar to those with the original Kohn−Sham LDA than Vosko−Wilk−Nusair results.) The Cu oxides contain the O2− ion, which is stable in a solid but emits an electron in a vacuum. This implies that the atomic wave equation of electrons for an isolated O2− in a vacuum lacks real solutions unless a well potential is added to the atomic potential. The well potential for the O2− basis set was calculated using the Coulomb potential generated by nuclei and electron clouds surrounding O2− in a solid. A relatively shallow well potential within an ion radius compared to the well depth usually used results in significant delocalization of electrons at the O2− site. This periodic molecular orbital method predicts insulating antiferromagnetic ordering in CaCuO2. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
Theoretical study on the reaction of butadiynyl radical (C4H) with ethylene (C2H4) to form C6H4 and H
Authors: Kim Joonghan , Ihee Hyotcherl
Published: May 2011

The reaction mechanisms of the butadiynyl radical (C4H) with ethylene (C2H4) to form H and C6H4 via hydrogen elimination are investigated using the density functional theory and high‐level ab initio methods. The calculated geometrical parameters and dipole moment of the 2Π state of C4H are in excellent agreement with previously reported values using CCSD(T) with large basis sets. The calculated reaction enthalpy is also in excellent agreement with that of previously reported value. These results indicate that theoretical level in this work is optimal and more expensive calculations may not be necessary for the systems studied in this work. Eight isomers of C6H4 are considered in this work, and we present the highly complex reaction pathways by grouping them into three categories; (i) pathways including only chain intermediates without any ring components, (ii) pathways including ring formations except the six‐membered ring, and (iii) pathways including the six‐membered ring. On the basis of the calculated results, the most favorable reaction pathway is simple and found in the first category; H elimination from the initial chain adduct of C4H with C2H4 yields H and one of C6H4 isomers (CH2CHCCCCH). This reaction is similar to that of the reaction of ethynyl (C2H) radical with C2H4. This result clarifies the assumption in the recent experimental kinetics study. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011.
A concentration result with application to subgraph count
Authors: Wolfovitz Guy
Published: May 2011

Let H = (V,E) be a k ‐uniform hypergraph with a vertex set V and an edge set E. Let V
p be constructed by taking every vertex in V independently with probability p. Let X be the number of edges in E that are contained in V
p. We give a condition that guarantees the concentration of X within a small interval around its mean. The applicability of this result is demonstrated by deriving new sub‐Gaussian tail bounds for the number of copies of small complete and complete bipartite graphs in the binomial random graph. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 2012
Fast and reliable reconstruction of phylogenetic trees with indistinguishable edges
Authors: Gronau Ilan , Moran Shlomo , Snir Sagi
Published: May 2011

Phylogenetic reconstruction methods attempt to reconstruct a tree describing the evolution of a given set of species using sequences of characters (e.g. DNA) extracted from these species as input. A central goal in this area is to design algorithms which guarantee reliable reconstruction of the tree from short input sequences, assuming common stochastic models of evolution. Thefast convergingreconstruction algorithms introduced in the last decade dramatically reduced the sequence length required to guarantee accurate reconstruction of the entire tree. However, if the tree in question contains even few edges which cannot be reliably reconstructed from the input sequences, then known fast converging algorithms may fail to reliably reconstruct all or most of the other edges. This calls for an adaptive approach suggested in this paper, calledadaptivefast convergence, in which the set of edges which can be reliably reconstructed gradually increases with the amount of information (length of input sequences) available to the algorithm.

This paper presents an adaptive fast converging algorithm which returns a partially resolved topology containing no false edges: edges that cannot be reliably reconstructed are contracted into high degree vertices. We also present an upper bound on the weights of those contracted edges, which is determined by the length of input sequences and the depth of the tree. As such, the reconstruction guarantee provided by our algorithm for individual edges is significantly stronger than any previously published edge reconstruction guarantee. This fact, together with the optimal complexity of our algorithm (linear space and quadratic‐time), makes it appealing for practical use. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 40, 350–384, 2011
Long‐Term structural changes of plasmid DNA studied by atomic force microscopy
Authors: Kim Byung I. , Clark Reilly , Clark Tyler
Published: May 2011

Long‐term stability of plasmid DNA (pDNA) conformations is critical in many research areas, especially those concerning future gene therapy. Despite its importance, the time‐evolution of pDNA structures has rarely been studied at a molecular resolution. Here, the time‐evolution of pDNA solutions spanning four years was observed with atomic force microscopy (AFM). The AFM data show that the pDNA molecules changed over time from isolated supercoiled structures, to aggregated supercoiled structures, to thin, branched network structures, and finally to wider, branched network structures. Additional topographical analysis of the AFM data suggests that the actions of residual proteins could be the main mechanism for the structural changes in our laboratory‐prepared pDNA. SCANNING 33:405–412, 2011. © 2011 Wiley Periodicals, Inc.