bluuebunny/crossref_metadata_2025 huggingface dataset:
Free‐Breathing 3D Cardiac MRI Using Iterative Image‐Based Respiratory Motion Correction
Authors: Moghari Mehdi H. , Roujol Sébastien , Chan Raymond H. , Hong Susie N. , Bello Natalie , Henningsson Markus , Ngo Long H. , Goddu Beth , Goepfert Lois , Kissinger Kraig V. , Manning Warren J. , Nezafat Reza
Published: November 2012

Respiratory motion compensation using diaphragmatic navigator gating with a 5 mm gating window is conventionally used for free‐breathing cardiac MRI. Because of the narrow gating window, scan efficiency is low resulting in long scan times, especially for patients with irregular breathing patterns. In this work, a new retrospective motion compensation algorithm is presented to reduce the scan time for free‐breathing cardiac MRI that increasing the gating window to 15 mm without compromising image quality. The proposed algorithm iteratively corrects for respiratory‐induced cardiac motion by optimizing the sharpness of the heart. To evaluate this technique, two coronary MRI datasets with 1.3 mm3 resolution were acquired from 11 healthy subjects (seven females, 25 ± 9 years); one using a navigator with a 5 mm gating window acquired in 12.0 ± 2.0 min and one with a 15 mm gating window acquired in 7.1 ± 1.0 min. The images acquired with a 15 mm gating window were corrected using the proposed algorithm and compared to the uncorrected images acquired with the 5 and 15 mm gating windows. The image quality score, sharpness, and length of the three major coronary arteries were equivalent between the corrected images and the images acquired with a 5 mm gating window (P‐value > 0.05), while the scan time was reduced by a factor of 1.7. Magn Reson Med, 70:1005–1015, 2013. © 2012 Wiley Periodicals, Inc.
The splicing factor SRSF6 is amplified and is an oncoprotein in lung and colon cancers
Authors: Cohen‐Eliav Michal , Golan‐Gerstl Regina , Siegfried Zahava , Andersen Claus L , Thorsen Kasper , Ørntoft Torben F , Mu David , Karni Rotem
Published: November 2012

An increasing body of evidence connects alterations in the process of alternative splicing with cancer development and progression. However, a direct role of splicing factors as drivers of cancer development is mostly unknown. We analysed the gene copy number of several splicing factors in colon and lung tumours, and found that the gene encoding for the splicing factor SRSF6 is amplified and over‐expressed in these cancers. Moreover, over‐expression of SRSF6 in immortal lung epithelial cells enhanced proliferation, protected them from chemotherapy‐induced cell death and converted them to be tumourigenic in mice. In contrast, knock‐down of SRSF6 in lung and colon cancer cell lines inhibited their tumourigenic abilities. SRSF6 up‐ or down‐regulation altered the splicing of several tumour suppressors and oncogenes to generate the oncogenic isoforms and reduce the tumour‐suppressive isoforms. Our data suggest that the splicing factor SRSF6 is an oncoprotein that regulates the proliferation and survival of lung and colon cancer cells.
Cancer‐associated somatic DICER1 hotspot mutations cause defective miRNA processing and reverse‐strand expression bias to predominantly mature 3p strands through loss of 5p strand cleavage
Authors: Anglesio MS , Wang Y , Yang W , Senz J , Wan A , Heravi‐Moussavi A , Salamanca C , Maines‐Bandiera S , Huntsman DG , Morin GB
Published: November 2012

Our group recently described recurrent somatic mutations of the miRNA processing gene DICER1 in non‐epithelial ovarian cancer. Mutations appeared to be clustered around each of four critical metal‐binding residues in the RNase IIIB domain of DICER1. This domain is responsible for cleavage of the 3′ end of the 5p miRNA strand of a pre‐mRNA hairpin. To investigate the effects of these cancer‐associated 'hotspot' mutations, we engineered mouse DICER1‐deficient ES cells to express wild‐type and an allelic series of the mutant DICER1 variants. Global miRNA and mRNA profiles from cells carrying the metal‐binding site mutations were compared to each other and to wild‐type DICER1. The miRNA and mRNA profiles generated through the expression of the hotspot mutations were virtually identical, and the DICER1 hotspot mutation‐carrying cells were distinct from both wild‐type and DICER1‐deficient cells. Further, miRNA profiles showed that mutant DICER1 results in a dramatic loss in processing of mature 5p miRNA strands but were still able to create 3p strand miRNAs. Messenger RNA (mRNA) profile changes were consistent with the loss of 5p strand miRNAs and showed enriched expression for predicted targets of the lost 5p‐derived miRNAs. We therefore conclude that cancer‐associated somatic hotspot mutations of DICER1, affecting any one of four metal‐binding residues in the RNase IIIB domain, are functionally equivalent with respect to miRNA processing and are hypomorphic alleles, yielding a global loss in processing of mature 5p strand miRNA. We further propose that this resulting 3p strand bias in mature miRNA expression likely underpins the oncogenic potential of these hotspot mutations. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
From chaos to split‐ups – SHG microscopy reveals a specific remodelling mechanism in ageing dystrophic muscle
Authors: Buttgereit Andreas , Weber Cornelia , Garbe Christoph S , Friedrich Oliver
Published: November 2012

Duchenne muscular dystrophy (DMD) is a common inherited muscle disease showing chronic inflammation and progressive muscle weakness. Absent dystrophin renders sarcolemma more Ca2+‐permeable, disturbs signalling and triggers inflammation. Sustained degeneration/regeneration cycles render muscle cytoarchitecture susceptible to remodelling. Quantitative morphometry was introduced in living cells using second‐harmonic generation (SHG) microscopy of myosin. As the time course of cellular remodelling is not known, we used SHG microscopy in mdx muscle fibres over a wide age range for three‐dimensional (3D) rendering and detection of verniers and cosine angle sums (CASs). Wild‐type (wt) and transgenic mini‐dystrophin mice (MinD) were also studied. Vernier densities (VDs) declined in wt and MinD fibres until adulthood, while in mdx fibres, VDs remained significantly elevated during the life span. CAS values were close to unity in adult wt and MinD fibres, in agreement with tight regular myofibril orientation, while always smaller in mdx fibres. Using SHG 3D morphometry, we identified two types of altered ultrastructure: branched fibres and a novel, previously undetected ‘chaotic’ fibre type, both of which can be classified by distinct CAS and VD combinations. We present a novel model of tissue remodelling in dystrophic progression with age that involves the transition from normal to chaotic to branched fibres. Our model predicts a ∼50% contribution of altered cytoarchitecture to progressive force loss with age. We also provide an improved automated image algorithm that is suitable for future ageing studies in human myopathies. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Targeting FLIP and Mcl‐1 using a combination of aspirin and sorafenib sensitizes colon cancer cells to TRAIL
Authors: Pennarun Bodvael , Kleibeuker Jan H , van Ek Wytske Boersma‐ , Kruyt Frank AE , Hollema Harry , de Vries Elisabeth GE , de Jong Steven
Published: November 2012

The multikinase inhibitor sorafenib is highly effective against certain types of cancer in the clinic and prevents colon cancer cell proliferation in vitro. Non‐steroidal anti‐inflammatory drugs, such as acetylsalicylic acid (aspirin), have shown activity against colon cancer cells. The aims of this study were to determine whether the combination of aspirin with sorafenib has enhanced anti‐proliferative effects and increases recombinant human tumour necrosis factor‐related apoptosis‐inducing ligand (rhTRAIL)‐induced apoptosis in the human SW948, Lovo, Colo205, Colo320, Caco‐2 and HCT116 colon cancer cell lines. In four cell lines, aspirin strongly stimulated the anti‐proliferative effects of sorafenib (∼four‐fold enhancement) by inducing cell cycle arrest. Furthermore, combining low doses of aspirin (≤ 5 mm) and sorafenib (≤ 2.5 µm) greatly sensitized TRAIL‐sensitive and TRAIL‐resistant colon cancer cells to rhTRAIL, much more potently than either drug combined with rhTRAIL. The increase in rhTRAIL sensitivity was due to inhibition of FLIP and Mcl‐1 protein expression following aspirin and sorafenib co‐treatment, as confirmed by knock‐down studies. Next, the clinical relevance of targeting FLIP and Mcl‐1 in colon cancer was examined. Using immunohistochemistry, we found that Mcl‐1 expression was significantly increased in colon adenoma and carcinoma patient material compared to healthy colonic epithelium, similar to the enhanced FLIP expression we recently observed in colon cancer. These results underscore the potential of combining low doses of aspirin with sorafenib to inhibit proliferation and target the anti‐apoptotic proteins FLIP and Mcl‐1 in colon cancer cells. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Preparation and characterization of magnetic star‐shaped amphiphilic copolymer nanoparticles of S‐Fe3O4‐PLA‐b‐MPEG
Authors: Chen Xiaoqian , Lu Ronghui , Meng Duo , Rong Yao , Yao Bolong , Ni Caihua
Published: November 2012

Magnetic star‐shaped amphiphilic copolymers (S‐Fe3O4‐PLA‐b‐MPEG) consisting of Fe3O4 as the core, poly(L,D‐lactide) (PLA) as the inner layer, and monomethyl polyethylene glycol (MPEG) as the out shell were synthesized. The syntheses included ring‐opening polymerization of L,D‐lactide initiated by hydroxyl modified Fe3O4 (Fe3O4‐(OH)
n), followed by the esterification of the PLA with MPEG. The structure of the star block copolymers were characterized by Fourier Transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, transmission electron microscopy, nanoparticle size analyzer, and vibrating sample magnetometer. The nanoparticles in aqueous solution were made from the amphiphilic star copolymer. The average size of the nanoparticles was adjustable and increased with the increase of the PLA segments in the copolymer. The cytotoxicity grade of the nanoparticles was zero determined by the analysis of cytotoxicity. The nanoparticles could potentially be used as the drug vehicles for magnetic‐response controlled release. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Glass fiber breakup in corotating twin screw extruder: Simulation and experiment
Authors: Bumm Sug Hun , White James L. , Isayev Avraam I.
Published: November 2012

The damage of glass fibers at various conditions was investigated in a corotating twin screw extruder by varying viscosity, screw speed, and screw configuration. Increasing the screw speed and melt matrix viscosity were found to increase the extent of fiber breakage. Based on the experimental data and Euler buckling theory, a composite modular kinetic model to describe glass fiber breakage was developed. Regions of the major and minor fiber breakage in a corotating twin screw extruder were found. The simulation program based on the experimental data and kinetic constants was developed for fiber breakage along the screw length. Comparisons were made between simulated results and experimental data indicating a reasonable quantitative agreement between them. Predictions of the model are also in general qualitative agreement with many published data on fiber breakage in twin screw extruders. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Electrically conductive composites of poly(urea‐formaldehyde) and cellulose filled with aluminum
Authors: Pinto Gabriel , Maaroufi Abdel‐Karim
Published: November 2012

This article addresses the preparation and characterization of composite materials obtained with compression molding of mixtures of aluminum powder and a commercial grade thermosetting resin of poly(urea‐formaldehyde) filled with α‐cellulose in powder form. The homogeneity of these composites was checked by the morphologies of the constituents (filler and matrix) by optical microscopy. The density of the composites was measured and compared with values calculated by assuming different void levels within the samples, to discuss the porosity effect, in connection with optical microscopy observations. Then, the dependence of electrical conductivity of the composites on volume fraction of the metal filler was investigated. The conductivity of the composites is <10−12 S/cm unless the metal content reaches the percolation threshold at a volume fraction of Vc = 38.6 vol%, beyond which the conductivity increases markedly by as much as nine orders of magnitude, indicating an insulator–conductor phase transition. The obtained results on electrical conductivity have been well interpreted with the statistical percolation theory. The deduced critical parameters, such as the threshold of percolation, Vc, the critical exponent, t, and the packing density coefficient, F, were in good accord with earlier studies. In addition, the hardness of samples remained almost constant with the increase of metal concentration. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Rheology and thermal behavior of polyamide reinforced with alumina whiskers
Authors: Abad María José , Ares Ana , Noguerol Rosalía , García Xoan , Cerecedo Carmen , Valcárcel Víctor , Caamaño J. Miguel , Guitián Francisco
Published: November 2012

Alumina whiskers were melt‐mixed with polyamide 12 to obtain new composites with high performance properties and similar processability of neat polyamide. Three kinds of alumina whiskers were used to prepare composites (purified fibers, ribbon‐shaped fibers and silica‐coated fibers). The rheology, morphology and thermal behavior of composites were evaluated as function of the type of whisker and its amount in the samples. In terms of rheological properties, modulus and viscosity were enhanced as function of the amount of filler added. Good dispersion of alumina whiskers in PA12 and an optimal filler‐matrix interface were observed in morphological tests independently of the kind of fiber used. Studies on crystallization behavior indicated the nucleation action of whiskers, although the most important changes in crystalline state of PA12 were observed with ribbon‐shaped and silica‐coated fibers. Whiskers improved significantly the thermal stability of polyamide. But kinetics of degradation process studied using Coats‐Redfern method indicates that the best behavior wasobtained principally with ribbon‐shaped and silica‐coated whiskers. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
The impact of creative tendency, academic performance, and self‐concept on creative science problem‐finding
Authors: Liu Mingxin , Hu Weiping , Adey Philip , Cheng Li , Zhang Xingli
Published: November 2012

This study was designed to address the impacts of science performance, science self‐concept, and creative tendency on the creative science problem‐finding (CSPF) ability of a sample of Chinese middle‐school students. Structural equation modeling was used to indicate that CSPF could be directly predicted by creative tendency and academic performance, and indirectly predicted by science self‐concept. The findings strongly support the idea that curiosity, imagination, and domain‐specific knowledge are important for CSPF, and science self‐concept could be mediated by knowledge that affects CSPF.
The preparation and properties of polystyrene/functionalized graphene nanocomposite foams using supercritical carbon dioxide
Authors: Li Chaoqun , Yang Guanghui , Deng Hua , Wang Ke , Zhang Qin , Chen Feng , Fu Qiang
Published: November 2012

In this work, polystyrene (PS)/functionalized graphene nanocomposite foams were prepared using supercritical carbon dioxide. Thermally reduced graphene oxide (TRG) and graphene oxide (GO) were incorporated into the PS. Subsequently, the nanocomposites were foamed with supercritical CO2. The morphology and properties of the nanocomposites and the nucleation efficiency of functionalized graphene in foaming PS are discussed. Compared with GO, TRG exhibited a higher nucleation efficiency and more effective cell expansion inhibition thanks to its larger surface area and better exfoliated structure. It is suggested that the factors that have a significant influence on the nucleation efficiency of TRG and GO originate from the differences in surface properties and chemical structure. Furthermore, PS/TRG nanocomposites and their nanocomposite foams also possess good electrical properties which enable them to be used as lightweight functional materials.© 2012 Society of Chemical Industry
Compatibilization of immiscible nylon 6/poly(vinylidene fluoride) blends using graphene oxides
Authors: Yang Jinghui , Feng Chenxia , Dai Jian , Zhang Nan , Huang Ting , Wang Yong
Published: November 2012

A new strategy to compatibilize immiscible blends is proposed, using graphene oxide (GO) nanosheets taking advantage of their unique amphiphilic structures. When 0.5 or 1 wt% GOs were incorporated in immiscible nylon 6/poly(vinylidene fluoride) (PVDF) (90/10 wt%) blends, the dimension of PVDF dispersed particles was markedly reduced and became more uniform, revealing a well‐defined compatibilization effect of GOs on the immiscible blends. Correspondingly, the ductility of the compatibilized blends increased several times compared with uncompatibilized immiscible blends. In order to explore the underlying compatibilization mechanism, Fourier transform infrared and Raman spectra were applied to suggest that the edge polar groups of GOs can form hydrogen bonds with nylon 6 while the basal plane of GOs can interact with electron‐withdrawing fluorine on PVDF chains leading to the so‐called charge‐transfer C–F bonding. In this case, GOs exhibit favorable interactions with both nylon 6 and PVDF phase, therefore stabilizing the interface during GO migrations from PVDF/GO masterbatch to nylon 6 phase, which can minimize the interfacial tension and finally lead to compatibilization effects. Obviously, this work may open a broad prospect for GOs to be widely applied as a new compatibilizer in industrial fields. © 2012 Society of Chemical Industry
Synthesis of poly(lactic acid)‐based polyurethanes
Authors: Chen Szu‐Hsien , Tsao Ching‐Ting , Chou Hung‐Chia , Chang Chih‐Hao , Hsu Ching‐Te , Chuang Ching‐Nan , Wang Chih‐Kuang , Hsieh Kuo‐Huang
Published: November 2012

Poly(lactic acid) (PLA) is a biodegradable aliphatic polyester, but its brittleness makes it unsuitable for many packaging and appliance applications. The goal of the work reported was to create novel poly(ester urethane)s that incorporate biodegradable poly(lactic acid) diols (PLA‐OHs) and good mechanical properties of increased molecular weight via crosslinked network formation for engineering plastics applications. Three kinds of polyols (PLA‐OHs, PLA‐OHs/poly(tetramethylene ether) glycol or PLA‐OHs/poly(butylene adipate) glycol (PBA)) and two kinds of diisocyanates (4,4‐diphenylmethane diisocyanate (MDI) or toluene 2,4‐diisocyanate (TDI)) were chosen for the soft and hard segments to compare their mechanical properties. In addition, 1,4‐butanediol and trimethylolpropane were each used as chain extender agents. Results showed the PLA/PBA‐polyurethanes (PLA/PBA‐PUs) of the MDI series and the PLA/PBA‐PUs of the TDI series had improved thermal stability and enhanced mechanical properties. Degradation behavior showed the PLA‐based polyurethanes could be degraded in phosphate‐buffered saline solution and enzyme solution. © 2012 Society of Chemical Industry
From high‐efficiency n‐type solar cells to modules exceeding 20% efficiency with aluminum‐based cell interconnection
Authors: Merkle Agnes , Schulte‐Huxel Henning , Blankemeyer Susanne , Feilhaber Ilka , Bock Robert , Steckenreiter Verena , Kajari‐Schroeder Sarah , Harder Nils‐Peter , Brendel Rolf
Published: November 2012

We present the integrated development of back‐contacted solar cells and an adequate module interconnection for a high‐efficiency photovoltaic module. We report on a large area (125 × 125) mm2 back‐junction back‐contact n‐type solar cell metallized with aluminum having a total area conversion efficiency of 20.7%. To transfer the high conversion efficiency to the module, we use the laser welding process named aluminum‐based mechanical and electrical laser interconnection for module integration of these back‐contacted solar cells. We further analyze the impact of the busbars of our back‐junction back‐contact cells on the cell performance and report on optimization of the cell/module interface. The new cells have an adapted rear‐side geometry by omitting the emitter busbar. A proof‐of‐concept module consisting of these cells is presented. Copyright © 2012 John Wiley & Sons, Ltd.
Urinary exosomes: A reservoir for biomarker discovery and potential mediators of intrarenal signalling
Authors: Dear James W. , Street Jonathan M. , Bailey Matthew A.
Published: November 2012

Over the last decade, there has been increasing research interest in urinary exosomes and their relationship with kidney physiology and disease. Protocols for isolating urinary exosomes have been refined and the exosomal proteome has been extensively catalogued and reported to contain proteins from the kidney's glomerulus and all sections of the nephron. In animal and human biomarker discovery studies, this proteome changes to reflect the underlying pathophysiology of certain kidney diseases. In addition to proteins, exosomes from urine have been demonstrated to contain RNA species, another new reservoir for biomarker discovery. Exosomes have the capacity to shuttle their cargo between kidney cells and change the recipient cell's proteome and function, and may represent a mechanism for cell‐to‐cell signalling along the nephron. Significant challenges remain; methods for urinary exosome collection need optimisation if “real‐life” clinical utility is to be achieved, consensus is needed regarding normalisation of changes in exosomal protein and RNA, larger scale exosome biomarker validation studies remain to be performed, and whether exosomes signal between cells in vivo remains an intriguing, but untested, hypothesis.
Calculated polar substituent effects on the stability of 3‐substituted(X) bicyclo[1.1.1]pent‐1‐yl cations and 4‐substituted(X) bicyclo[2.2.1]hept‐1‐yl cations: a DFT study
Authors: Adcock William
Published: November 2012

The effects of substituents on the stability of 3‐substituted(X) bicyclo[1.1.1]pent‐1‐yl cations (3) and 4‐substituted(X) bicyclo[2.2.1]hept‐1‐yl cations (4), for a set of substituents (X = H, NO2, CN, NC, CF3, CHO, COOH , F, Cl, HO, NH2, CH3, SiH3, Si(CH3)3, Li, O−, and NH3+) covering a wide range of electronic substituent effects were calculated using the DFT theoretical model at the B3LYP/6‐311 + G(2d,p) and B3LYP/6‐31 + G (d) levels of theory, respectively. Linear regression analysis was employed to explore the relationship between the calculated relative hydride affinities (ΔE, kcal/mol) of the appropriate isodesmic reactions for 3/4 and polar field/group electronegativity substituent constants (σF and σχ, respectively). The analysis reveals that the ΔE values for both systems are best described by a combination of both substituent constants. The result highlights the importance of the σχ dependency of charge delocalization in these systems. Copyright © 2012 John Wiley & Sons, Ltd.
Thermal reaction of electron deficient 4‐oxo‐4H‐pyrazole 1,2‐dioxide with cycloheptatriene: the first examples of the formation of an endo‐[4π + 6π]‐cycloadduct and an intramolecular 1,3‐dipolar reaction leading to a heterocage
Authors: Yamaguchi Koki , Eto Masashi , Yoshitake Yasuyuki , Harano Kazunobu
Published: November 2012

The reaction of 3,5‐bis(methoxycarbonyl)‐4‐oxo‐4H‐pyrazole 1,2‐dioxide (1a) with 1,3,5‐cycloheptatriene (2b) gave a mixture of the novel endo‐[4 + 6]‐cycloadduct (4ab), anti‐exo‐[4 + 2]‐cycloadduct (5ab), and the heterocage (6ab) derived from the intramolecular 1,3‐dipolar cycloaddition reaction of the syn‐endo‐[4 + 2]‐cycloadduct. Analogous endo‐[4 + 6] selectivity in 1,3‐dipolar cycloadditions has not been reported previously. The X‐ray analysis indicates that 6ab has a very long Nsp3–Nsp3 bond distance of 1.617(4) Å. The cycloaddition behaviour is discussed on the basis of transition‐state structures optimized at the B3LYP/6‐31G(d) level of theory, from which predictions of the peri‐, regio‐, and stereoselectivities agreed well with the experimental results. Copyright © 2012 John Wiley & Sons, Ltd.
Alternating, gradient, block, and block–gradient copolymers of ethylene and norbornene by Pd–Diimine‐Catalyzed “living” copolymerization
Authors: Xiang Peng , Ye Zhibin
Published: November 2012

We demonstrate, in this article, the facile synthesis of a broad class of low‐polydispersity ethylene–norbornene (E–NB) copolymers having various controllable comonomer composition distributions, including gradient, alternating, diblock, triblock, and block–gradient, through “living”/quasiliving E–NB copolymerization facilitated with a single Pd–diimine catalyst (1). This synthesis benefits from two remarkable features of catalyst 1, its high capability in NB incorporation and high versatility in rendering E–NB “living” copolymerization at various NB feed concentrations ([NB]0) while under an ethylene pressure of 1 atm and at 15 °C. At higher [NB]0 values between 0.42 and 0.64 M, E–NB copolymerization with 1 renders nearly perfect alternating copolymers. At lower [NB]0 values (0.11–0.22 M), gradient copolymers yield due to gradual reduction in NB concentration, with the starting chain end containing primarily alternating segments and the finishing end being hyperbranched polyethylene segments. Through two‐stage or three‐stage “living” copolymerization with sequential NB feeding, diblock or triblock copolymers containing gradient block(s) have been designed. This work thus greatly expands the family of E–NB copolymers. All the copolymers have controllable molecular weight and relatively low polydispersity (with polydispersity index below 1.20). Most notably, some of the gradient and block–gradient copolymers have been found to exhibit the characteristic broad glass transitions as a result of their possession of broad composition distribution. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Thermoresponsive NIPAM block copolymers containing densely grafted poly(vinyl ether) brushes synthesized by a combination of living cationic polymerization and RAFT polymerization
Authors: Minoda Masahiko , Shimizu Tatsuya , Miki Sadao , Motoyanagi Jin
Published: November 2012

Diblock copolymers consisting of a multibranched polymethacrylate segment with densely grafted poly[2‐(2‐methoxyethoxy)ethyl vinyl ether] pendants and a poly(N‐isopropylacrylamide) segment were synthesized by a combination of living cationic polymerization and RAFT polymerization. A macromonomer having both a poly[2‐(2‐methoxyethoxy)ethyl vinyl ether] backbone and a terminal methacryloyl group was synthesized by living cationic polymerization. The sequential RAFT copolymerizations of the macromonomer and N‐isopropylacrylamide in this order were performed in aqueous media employing 4‐cyanopentanoic acid dithiobenzoate as a chain transfer agent and 4,4′‐azobis(4‐cyanopentanoic acid) as an initiator. The obtained diblock copolymers possessed relatively narrow molecular weight distributions and controlled molecular weights. The thermoresponsive properties of these polymers were investigated. Upon heating, the aqueous solutions of the diblock copolymers exhibited two‐stage thermoresponsive properties denoted by the appearance of two cloud points, indicating that the densely grafted poly[2‐(2‐methoxyethoxy)ethyl vinyl ether] pendants and the poly(N‐isopropylacrylamide) segments independently responded to temperature. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Emulsion polymerization of vinyl acetate using iodine‐transfer and RAFT radical polymerizations
Authors: Nomura Naoki , Shinoda Keiji , Takasu Akinori , Nagata Kenji , Inomata Katsuhiro
Published: November 2012

This study deals with control of the molecular weight and molecular weight distribution of poly(vinyl acetate) by iodine‐transfer radical polymerization and reversible addition‐fragmentation transfer (RAFT) emulsion polymerizations as the first example. Emulsion polymerization using ethyl iodoacetate as the chain transfer agent more closely approximated the theoretical molecular weights than did the free radical polymerization. Although 1H NMR spectra indicated that the peaks of α‐ and ω‐terminal groups were observed, the molecular weight distributions show a relatively broad range (Mw/Mn = 2.2–4.0). On the other hand, RAFT polymerizations revealed that the dithiocarbamate 7 is an excellent candidate to control the polymer molecular weight (Mn = 9.1 × 103, Mw/Mn = 1.48), more so than xanthate 1 (Mn = 10.0 × 103, Mw/Mn = 1.89) under same condition, with accompanied stable emulsions produced. In the Mn versus conversion plot, Mn increased linearly as a function of conversion. We also performed seed‐emulsion polymerization using poly(nonamethylene L‐tartrate) as the chiral polyester seed to fabricate emulsions with core‐shell structures. The control of polymer molecular weight and emulsion stability, as well as stereoregularity, is also discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Molecular dynamics simulation of carbon nanostructures: The C60 buckminsterfullerene
Authors: László István , Zsoldos Ibolya
Published: November 2012

Molecular dynamics calculations can reveal the physical and chemical properties of various carbon nanostructures or can help to devise the possible formation pathways. In our days the most well‐known carbon nanostructures are the fullerenes, the nanotubes, and the graphene. The fullerenes and nanotubes can be thought of as being formed from graphene sheets, i.e., single layers of carbon atoms arranged in a honeycomb lattice. Usually the nature does not follow the mathematical constructions. Although the first time the C60 and the C70 were produced by laser irradiated graphite, the fullerene formation theories are based on various fragments of carbon chains and networks of pentagonal and hexagonal rings. In the present article various formation pathways for the buckminsterfullerene C60 molecule will be presented.

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Encapsulating graphene by ultra‐thin alumina for reducing process contaminations
Authors: Dauber Jan , Terrés Bernat , Trellenkamp Stefan , Stampfer Christoph
Published: November 2012

We discuss a fabrication process for making graphene devices based on encapsulated graphene for reducing contaminations during individual processing steps. A 3–5 nm alumina layer is deposited directly after exfoliating graphene, protecting it during the entire processing. We show that the visibility of the encapsulated graphene is sufficient to identify graphene flakes and Raman spectra exhibit the characteristic finger print. We perform transport measurements to study the sample quality and compare the results with graphene samples processed without an alumina layer. In particular we observe a higher yield and significantly reduced contact resistances for devices fabricated with the here presented method.

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Graphene flake with metal (Cr/Au) contacts covered with an ultra‐thin (3–5 nm) oxidized aluminum layer (left) and without the layer (right).
On the low temperature microwave absorption anomaly in single‐wall carbon nanotubes
Authors: Karsa Anita , Quintavalle Dario , Forró László , Simon Ferenc
Published: November 2012

The low temperature microwave absorption anomaly reported by Corzilius et al. [Phys. Rev. B 75, 235416 (2007)] in single‐wall carbon nanotubes (SWCNTs) is revisited. It was originally reported that the microwave absorption of CVD grown SWCNTs shows an unexpected increase below ∼20 K (using flow cryostats) which depends on the microwave power. The original observation was made using the microwave cavity perturbation method while sweeping the microwave frequency. We reproduced this effect on arc‐discharge based SWCNTs, using static cryogenic conditions with cooled microwave cavities, and employing a stable frequency source locked to the cavity resonance. Our observation shows that the microwave absorption anomaly is robust against the tube type and the experimental conditions.
Optically induced spin echoes in a Tm2+ doped crystal
Authors: Moriyasu T. , Yamauchi T. , Kohmoto T.
Published: November 2012

The dynamics of the optically induced magnetization was observed by using polarization spectroscopy with the pump‐probe technique. We observed, as an alloptical manipulation of spin coherence in solids, the optically induced free induction decay and spin echoes in the ground state of the thulium ion doped in fluoride crystals.

A vector model of the optically induced spin echoes for on‐resonant manipulation is considered. The application of spin echoes to solids is very important because of the possibility of the fast spin manipulation (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation of high quality ZnSe nanowires dominated by excitonic emission
Authors: Fernandes Carlos , Ruda Harry , Saxena Ankur , Souza Christina de
Published: November 2012

A comprehensive model for the vapour liquid solid based growth of ZnSe nanowires is developed and applied to the optimisation of growth conditions for ZnSe nanowires. The model provided insight into the role of fluid dynamics and adatom incorporation, on the growth of nanowires. When applied experimentally, with appropriate conditions we show how high quality nanowires can be synthesized. In particular, such nanowires were shown to be dominated by excitonic emission with narrow linewidth attributed to free exciton and acceptor bound exciton emissions. The latter was shown to originate from VZn and related complexes, and as expected the emission is accompanied by strong LO phonon emission consistent with the high quality of the nanowires. This work can hence provide guidance for choice of growth conditions for exceptional quality ZnSe nanowires suitable for optoelectronic applications. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of Er3+‐doped glasses for solar‐pumped lasers
Authors: Iwata Yasuyuki , Suzuki Takenobu , Ohishi Yasutake
Published: November 2012

The quantum efficiency (QE) of Er3+‐doped silicate, tellurite, phosphate and fluoride glasses have been examined under simulated sunlight excitation. The maximum of total QE, the sum of QE of 4S3/2, 4I11/2, 4I13/2→4I15/2 and 4S3/2→4I13/2 transition, is 75% and the maximum of QE1530, the QE of the 4I13/2→4I15/2 transition at 1530 nm, is 34% for 5.47×1019 cm‐3 Er3+‐doped fluoride glass. The figure of merit as laser media στ of silicate glass is 1.00×10‐22 cm2sec, which is the highest in 4 glasses. Although QE1530 of silicate is lower than fluoride, it is possible to compensate the low quantum efficiency to optimize the fiber laser design. Therefore Er3+‐doped fluoride and silicate glasses are expected to be promising candidates as solar‐pumped glass laser (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarization dependence of four‐wave mixing via biexcitons in CuCl microcavities
Authors: Matsuura S. , Mitsumori Y. , Kosaka H. , Edamatsu K. , Miyazaki K. , Kanatani Y. , Kim D. , Nakayama M. , Oohata G. , Oka H. , Ajiki H. , Ishihara H.
Published: November 2012

We studied the CuCl microcavity designed for the enhancement of the biexciton‐photon coupling, in terms of spectrally resolved four‐wave mixing. We observed the strong dependence of the spectrum on the polarization of the pump pulses and the polarization correlation between the pump pulses and the four‐wave mixing signal, suggesting that the biexciton state is successfully formed in the CuCl microcavity. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mn‐doping effect of photoluminescence on AgInS2
Authors: Paucar Raul , Miyamoto Umihito , Ohtani Naoki , Seo Takuya , Honjo Kazuhiro , Shim YongGu , Tokuda Takahiro , Yoshino Kenji , Wakita Kazuki
Published: November 2012

The effects of Mn‐doping on the photoluminescence spectra of AgInS2 bulk‐crystals grown by the hot‐press method have investigated by using a confocal microspectroscopy system. For Mn‐doped crystals, the emission peak located at 1.568 eV appears in addition to two peaks which exist on non‐doped samples. The lower energy peaks blow 1.8 eV are considered to be attributed to free‐to‐bound transition. We also examined temperature dependence of emission intensity of these peaks and obtained their activation energy. The energy values seem to correspond to energy levels related with the emissions because non‐doped and Mn‐doped samples indicated to be n‐type (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Acetylcholinesterase inhibitors: Modeling potential candidates
Authors: Kiametis Alessandra S. , Martins João B. L. , Romeiro Luiz A. S. , Gargano Ricardo
Published: November 2012

Alzheimer's disease is the leading cause of dementia for elderly people. The main active therapeutic is supported on the increased levels of acetylcholine in the synaptic cleft, based on reversible inhibition of the acetylcholinesterase (AChE) enzyme. This article aims to propose possible inhibitor candidates for AChE, designed from nonisoprenoid lipids of cashew (Anacardium occidentale), and based on several electronic properties. These electronic properties were obtained through B3LYP/6‐311+G(2d,p) calculation level. Principal component analysis reveals that from the set of studied molecular structures a small group is correlated with donepezil, a drug with known biological activity. © 2012 Wiley Periodicals, Inc.
Balancing your technology‐sourcing portfolio: How sourcing mode diversity enhances innovative performance
Authors: Van de Vrande Vareska
Published: November 2012

With external innovation becoming more and more important, many firms struggle with the question of how to balance their technology‐sourcing portfolio. This study addresses this issue by looking at the effects of portfolio diversity on performance outcomes and the conditions under which diversity is most likely to materialize. Using a dataset of strategic investments by pharmaceutical firms, the results show that the variance in relative technological proximity between the focal firm and its partners exhibits an inverted U‐shaped relationship with innovative performance and that this relationship is affected by the diversity of the external sourcing modes used in the portfolio.
Surfactant‐Concentration‐Dependent Shape Evolution of Au–Pd Alloy Nanocrystals from Rhombic Dodecahedron to Trisoctahedron and Hexoctahedron
Authors: Zhang Jiawei , Hou Changping , Huang Huang , Zhang Lei , Jiang Zhiyuan , Chen Guangxu , Jia Yanyan , Kuang Qin , Xie Zhaoxiong , Zheng Lansun
Published: November 2012

The surface structure‐controlled synthesis of noble metal nanocrystals (NCs) bounded by high‐index facets has become a hot research topic due to their potential to significantly improve catalytic performance. This study reports the preparation of monodisperse Au–Pd alloy NCs with systematic shape evolution from rhombic dodecahedral (RD) to trisoctahedral (TOH), and hexoctahedral (HOH) structures by varying the concentration of surfactant in the surfactant‐mediated synthesis. The as‐prepared three kinds of alloy NCs possess almost the same size and composition as each other. It is suggested that the surfactant containing long‐chain octadecyltrimethyl ammonium (OTA+) ions plays a key role in the formation of high index facets, and the crystal growth kinetics may also have an effect on the formation of different nanocrystal morphologies. In addition, the catalytic activities of these NCs are evaluated by structure‐sensitive reactions, including ethanol electro‐oxidation and the catalytic reduction of 4‐nitrophenol (4‐NPh). These three types of Au–Pd alloy NCs exhibit different catalytic selectivities towards these two reactions. The catalytic activities toward electro‐oxidation of ethanol are in the order of HOH > RD > TOH, which follows the order of their corresponding surface energies. However, the activities toward catalytic reduction of 4‐NPh are in the order of RD > TOH > HOH, which should be related to the local structure of the surfaces.
Exact fast computation of band depth for large functional datasets: How quickly can one million curves be ranked?
Authors: Sun Ying , Genton Marc G. , Nychka Douglas W.
Published: November 2012

Band depth is an important nonparametric measure that generalizes order statistics and makes univariate methods based on order statistics possible for functional data. However, the computational burden of band depth limits its applicability when large functional or image datasets are considered. This paper proposes an exact fast method to speed up the band depth computation when bands are defined by two curves. Remarkable computational gains are demonstrated through simulation studies comparing our proposal with the original computation and one existing approximate method. For example, we report an experiment where our method can rank one million curves, evaluated at fifty time points each, in 12.4 seconds with Matlab. Copyright © 2012 John Wiley & Sons, Ltd.
The Influence of Second Language Experience and Accent Familiarity on Oral Proficiency Rating: A Qualitative Investigation
Authors: Winke Paula , Gass Susan
Published: November 2012

This study investigates whether raters' knowledge of test takers' first language (L1) affects how the raters orient themselves to the task of rating oral speech. The authors qualitatively investigated the effects of accent familiarity on raters' score assignment processes. Twenty‐six trained raters with a second language of Mandarin Chinese, Korean, or Spanish rated English speech samples from 72 English language learners from three L1 backgrounds (Mandarin Chinese, Korean, and Spanish). Afterward, raters watched videos of themselves rating and discussed their rating processes. Analyses of data, assisted by the qualitative analysis software package QSR NVivo 8, revealed that some raters attended to and were influenced by test‐taker accent and L1. Raters who were heritage language learners discussed how their personal heritage status influenced how they thought about the speech samples from speakers whose L1 matched their heritage language. Although sensitivity to test‐taker accents seemed to occur naturally in the rating process, findings suggest that when raters have learned or know, to varying degrees, the test takers' L1, they tend to orient themselves to the speech in a biased way, compromising test reliability.
Synthesis, X‐ray Structures, and Luminescent Properties of Three Organically Templated Copper(I) Halides via in situ Solvothermal Reduction Reactions
Authors: Xin Bingjing , Li Yun , Zeng Guang , Peng Yu , Li Guanghua , Shi Zhan , Feng Shouhua
Published: November 2012

Three new organically templated copper(I) halides formulated (C10H22N2)2[Cu4I8] (1), (C10H22N2)2[Cu4I4Br4] (2), and C20H44N4[Cu4I4Br4] (3) {C10H22N2 = N,N′‐diethyl‐1, 4‐diazabicyclo‐[2.2.2]octane (T1), C20H44N4 = 4, 4′‐(butane‐1, 4‐diyl)bis(1‐ethyl‐1, 4‐diazonia‐bicyclo[2.2.2]octane) (T2)} were synthesized under solvothermal conditions by an in situ copper reduction route. The structures of these compounds are constructed by similar inorganic anion cluster skeleton, formulated Cu4X4X′4 (X = I, X′ = I, Br), and organic templates. The organic templates T1 and T2 in the structures originated from the in situ N‐alkylation reaction between DABCO (DABCO = N, N′‐dimethyl‐1, 4‐diazabicyclo[2.2.2]octane), alcohol solution, and alkyl bromine. Compounds 1–3 were characterized by X‐ray crystal structure, elemental analysis, TG, IR, XRD, and XPS. These compounds exhibit strong pale green, orange, and light orange luminescence at ambient temperature, respectively, and the luminescent properties of them in the solid state were also investigated.
Syntheses, Structures, and Fluorescence of Two Novel 2D ­Zinc(II) Layered Frameworks Based on 3‐Amino‐1, 2, 4‐triazole
Authors: Gao Jin‐Ying , Xiong Xia‐Hua , Chen Chu‐Jun , Xie Wei‐Ping , Ran Xing‐Rui , Yue Shan‐Tang
Published: November 2012

Two 2D zinc(II) layered coordination polymer compounds [Zn2(atz)2(na)2]n (1), and [Zn(atz)(ina)]n (2) (Hatz = 3‐amino‐1H‐1, 2, 4‐triazole, na = nicotinic acid, ina = isonicotinic acid) were synthesized and structurally characterized by elemental analysis, FT‐IR, thermogravimetric analysis (TGA), powder X‐ray diffraction (PXRD), and single‐crystal X‐ray diffraction. The interconnection of a coplanar six‐membered hexagonal ring and a 16‐membered non‐planar chair‐like ring results in a 2D sheet with (4, 82) topological network. Hydrogen bonds connect the neighboring planes into 3D supramolecular architectures. Furthermore, both complexes exhibit strong luminescent properties in the solid state at room temperature.
Six and seven loop Konishi from Lüscher corrections
Authors: Bajnok Zoltán , Janik Romuald A.
Published: November 2012

Abstract

In the present paper we derive six and seven loop formulas for the anomalous dimension of the Konishi operator in N=4 SYM from string theory using the technique of Lüscher corrections. We derive analytically the integrand using the worldsheet S-matrix and evaluate the resulting integral and infinite sum using a combination of high precision numerical integration and asymptotic expansion. We use this high precision numerical result to fit the integer coefficients of zeta values in the final analytical answer. The presented six and seven loop results can be used as a cross-check with FiNLIE on the string theory side, or with direct gauge theory computations. The seven loop level is the theoretical limit of this Lüscher approach as at eight loops double-wrapping corrections will appear.
Comparative Effectiveness of Chemotherapy in Elderly Patients with Metastatic Colorectal Cancer
Authors: Satram-Hoang Sacha , Lee Luen , Yu Shui , Guduru Sridhar R. , Gunuganti Ashokvardhan R. , Reyes Carolina , McKenna Edward
Published: November 2012

Purpose

Treatment advances have improved outcomes in clinical trials of patients with metastatic colorectal cancer (mCRC). Less is known about these effects for patients in real-world settings. This study evaluated treatment patterns and survival in older, demographically diverse patients with mCRC.

Methods

A retrospective cohort analysis was performed for 4,250 patients from January 1, 2000 to December 31, 2007 using linked Surveillance, Epidemiology, and End Results-Medicare database. Patients were ≥66 years, enrolled in Medicare parts A and B, and received first-line treatment with fluorouracil and leucovorin (5-FU/LV), capecitabine (CAP), 5-FU/LV plus oxaliplatin (FOLFOX), or CAP and oxaliplatin (CAPOX). Cox regression with backward elimination and propensity score-weighted Cox regression estimated relative risk of death. Date of last follow-up was December 2009. Statistical comparisons were made between 5-FU/LV vs. CAP and FOLFOX vs. CAPOX.

Results

Compared to 5-FU/LV, patients treated with CAP were older (mean age 78 vs. 76; P < 0.0001) and more likely female (61 vs. 54 %; P = 0.0017), while patients receiving CAPOX and FOLFOX were similar in age (mean age 74 vs. 73; P = 0.0924). Complications requiring medical resource utilization following initiation of therapy were significantly higher among patients administered with 5-FU/LV (54 %) vs. CAP (17 %; P < 0.0001) and FOLFOX (75 %) vs. CAPOX (57 %; P < 0.0001). The multivariate analysis revealed no significant differences in survival between 5-FU/LV and CAP and between FOLFOX and CAPOX.

Conclusions

Overall survival was comparable between CAP and 5-FU/LV and between CAPOX and FOLFOX with fewer complications requiring medical resource utilization associated with CAP and CAPOX, thus confirming clinical trial results.
CCN2/CTGF binds to fibroblast growth factor receptor 2 and modulates its signaling
Authors: Aoyama Eriko , Kubota Satoshi , Takigawa Masaharu
Published: November 2012

FGFR3
binds to
CCN2
by protein array (View interaction)