bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of single‐walled carbon nanotubes synthesized using iron and cobalt nanoparticles derived from self‐assembled diblock copolymer micelles
Authors: Fu Qiang , Reed Luke , Liu Jie , Lu Jennifer
Published: January 2010

We present a comparative study of single‐walled carbon nanotubes grown using iron and cobalt nanoparticles as catalysts via the chemical vapor deposition approach. Monodispersed iron and cobalt oxide nanoparticles with an average size of 2 nm were prepared using a polystyrene‐b‐poly (4‐vinylpyridine) diblock copolymermicelle template. The 2 nm iron oxide nanoparticles generated single‐walled carbon nanotubes with an average diameter of 1.5 nm while 2 nm cobalt oxide nanoparticles produced single‐walled carbon nanotubes with an average diameter of 1.0 nm. To achieve high growth yield using iron nanoparticles as catalyst, higher carbon feed rate is required. These findings demonstrate the importance of the synergic interaction between catalyst and carbon precursor in single‐walled carbon nanotube formation. It also elucidates the important role of catalyst chemical composition on carbon nanotube properties. Copyright © 2010 John Wiley & Sons, Ltd.
Synthesis and characterization of polypyrrole composites for corrosion protection of steel
Authors: Selvaraj M. , Palraj S. , Maruthan K. , Rajagopal G. , Venkatachari G.
Published: January 2010

Corrosion protection performance of epoxy polyamide coatings containing polypyrrole (PPy) composites for steel has been studied. PPy and its composites have been synthesized chemically using potassium permanganate and potassium per sulfate as oxidants. The PPy has been characterized by four probe method for conductivity, atomic absorption spectroscopy for elemental analysis, and Fourier transform infrared spectra for proving the incorporation of dopant in this polymers. The X‐ray diffraction (XRD) study has revealed the presence of manganese dioxide in the polymer. The elemental analysis and the thermo gravimetric analysis measurements showed that the presence of manganese dioxide in the polymer is about 75%. The thermal stability of deprotonated polymer has improved. Electrochemical impedance spectroscopic analysis indicated that the epoxy polyamide/PPy‐MnO2 coating showed the maximum resistance value of 2.196 × 107 Ω cm2 after 30 days immersion in 3% sodium chloride solution. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Fabrication and properties of solution‐cast polyaniline/carboxymethylchitin blend films
Authors: Thanpitcha Tuspon , Sirivat Anuvat , Jamieson Alexander M. , Rujiravanit Ratana
Published: January 2010

Blend films consisting of polyaniline in emeraldine base form (PANI EB) dispersed in partially cross‐linked carboxymethylchitin (CM‐chitin) were prepared by solution casting, and characterized for their physical, thermal, and electrical properties. Homogeneous and mechanically robust blend films were obtained having PANI EB contents up to 50 wt % in the CM‐chitin matrix. FTIR spectra confirm intimate mixing of the two blend components. The thermal stability of the blend films increased with increase of PANI EB content, suggesting the formation of an intermolecular interaction, such as hydrogen bonding, between PANI EB and CM‐chitin chains. The addition of PANI EB into the pure CM‐chitin film resulted in a decrease in electrical conductivity of the films owing to disruption of ionic conduction of the CM‐chitin structure. After doping the blend films by immersion in HCl solution, the electrical conductivity of the HCl‐doped films increased with increase of the PANI EB content to a maximum value of the order of 10−3 S/cm at 50 wt % PANI EB content. The electrical conductivity of the blend films was also dependent on the HCl concentration as well as on the type of acid dopant. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of lactose‐containing glycopolymer‐grafted silica gel particles
Authors: Guo Tian‐Ying , Liu Ping , Xia Yong‐Qing , Song Mou‐Dao
Published: January 2010

The surface free‐radical graft polymerization of 2‐O‐meth‐acryloyloxyethoxyl‐(2,3,4,6‐tetra‐O‐acetyl‐β‐D‐galactopyranosyl)‐(1‐4)‐2,3,6‐tri‐O‐acetyl‐β‐D‐glucopyranoside onto silica gel particles has been carried out with azobis (isobutyronitrile) as initiator. The grafting reaction conditions and the glycopolymer‐grafted silica gel particles have been investigated in detail. Chromatographic experiments have been attempted on glycopolymer‐modified silica gel particles as a stationary phase under normal phase conditions, and it was found that a certain separation effect of the quercetin and its derivant isorhamnetin was achieved. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Benzotrifluoromethyl group‐substituted poly(para‐phenylenevinylene): Effect on solubility, optical, and electronic properties
Authors: Chatterjee Shyambo , Kumar Sen Suman , Maji Samarendra , Dasgupta Barnali , Banerji Pallab , Banerjee Susanta
Published: January 2010

A new organosoluble benzotrifluoromethyl group containing poly(p‐phenylenevinylene) (BTFM‐PPV) has been synthesized via Gilch polymerization. The polymer is soluble in common organic solvents such as tetrahydrofuran, chloroform, dichloromethane, toluene, and xylene. BTFM‐PPV exhibited fluorescence emission peak with a very high blue shift at 474 nm with an excitation wavelength at 420 nm compared with many other PPV derivatives reported earlier. Incorporation of fluorated bezotrifluoromethyl pendent group in the PPV backbone lowers the HOMO and LUMO energy levels of BTFM‐PPV (2.48 eV) which retarded the hole injection and increase the electron injection in the device. The current–voltage (I–V) characteristic of the polymer was measured by fabricating the polymer as ITO/BTFM‐PPV/Al diode. The device performance was markedly improved by incorporation of 4‐fluoro‐3trifluoromethylphenyl units into the polymer main chain. The turn on voltage of the device observed from the I–V measurements was 7 V. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Poly(vinyl alcohol) and layered double hydroxide composites: Thermal and mechanical properties
Authors: Ramaraj B. , Nayak Sanjay K. , Yoon Kuk Ro
Published: January 2010

Nanocomposites of poly(vinyl alcohol) (PVA) with Mg‐Al layered double hydroxides (LDHs) were prepared with different compositions, viz., 2, 4, 6, and 8 wt %, of LDH, by solution‐intercalation method. The effect of LDH contents on thermal, physicomechanical, and morphological property of PVA films were investigated. Differential scanning calorimetric analysis reveals that LDH layers promote a new crystalline phase for PVA. The tensile analysis of PVA/LDH nanocomposites indicates reduction in tensile strength and modulus with change in LDH concentration and moisture. The microstructure analysis by optical microscopy and scanning electron microscopy demonstrates exfoliation and dispersion of LDHs in the PVA matrix in a disorderly fashion. The primary focus of the present investigation is to explore the potential of LDHs as nanofiller in a polyhydroxy polymer without surface modification. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effects of solvent sort, PES and PVP concentration on the properties and morphology of PVDF/PES blend hollow fiber membranes
Authors: Wu Lishun , Sun Junfen , He Chunju
Published: January 2010

Poly (vinylidene fluoride) (PVDF)/polyethersulfone (PES) hollow‐fiber membranes were spun by dry–wet spinning setup. PVDF and PES were employed as base polymers. Four different solvents including dimethyl sulphoxide, dimethyl formamide, 1‐methyl‐2‐pyrrolidone, and dimethyl acetamide (DMAc) were used as the solvents. Polyvinylpyrrolidone (PVP) was used as pore‐forming additive. The preparation variables in this work are sort of solvents, content ratio of PVDF/PES, and concentration of PVP. The membranes prepared by phase inversion were characterized by using scanning electron microscopy. Membrane performance was evaluated by shrinkage ratio, pure water flux and retention to bovine serum albumin (BSA). The shrinkage ratio of PVDF/PES blend hollow fiber membrane decreases when DMAc was used as a solvent. The pure water flux of blend membranes reaches the maximum and the retention to BSA reaches the minimum when the casting solution contains 1.5 wt % PES. The pure water flux reaches the maximum when the concentration of PVP is 5 wt %. The retention to BSA decreases and the shrinkage ratio increases with PVP concentration increasing. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Glutaraldehyde‐crosslinked poly(vinyl alcohol) hydrogel discs for the controlled release of antidiabetic drug
Authors: More Swapnil M. , Kulkarni Raghavendra V. , Sa Biswanath , Kayane Navanath V.
Published: January 2010

Hydrogel discs of poly(vinyl alcohol) loaded with glipizide, an oral antidiabetic drug, were prepared with glutaraldehyde (GA) as a crosslinker. Various formulations were prepared with various amounts of polymer, GA, and initial drug. The prepared hydrogel discs were characterized by thermogravimetric analysis, differential scanning calorimetric analysis, and X‐ray diffractometry. The dynamic swelling behavior and drug‐release patterns were dependent on the crosslink density. The hydrogel discs were capable of releasing drug for up to 24 h. The discs that were prepared with a higher concentration of GA released the drug more slowly. The release data were fitted to an empirical equation to determine the transport mechanism, which indicated a non‐Fickian trend for drug transport. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Investigation of thermally conducting phase‐change materials based on polyethylene/wax blends filled with copper particles
Authors: Molefi J. A. , Luyt A. S. , Krupa I.
Published: January 2010

This article reports on the morphology, melting and crystallization behavior, thermal stability, tensile properties, and thermal conductivity of phase‐change materials (PCM) for thermal energy storage. These materials were based on a soft Fischer‐Tropsch paraffin wax (PCM) blended with low‐density polyethylene, linear low‐density polyethylene, and high‐density polyethylene. These immiscible blends were melt‐mixed with copper (Cu) microparticles (up to 15 vol %) to improve the thermal conductivity in the matrix material. The presence of the Cu microparticles in the PCMs did not significantly change the crystallization behavior, thermal stability, or tensile properties of the blend composites in comparison with the corresponding polyethylene/wax blends and polyethylene/Cu composites. The observed differences were related to the fact that the wax seemed to have a higher affinity for the Cu particles than any of the polyethylenes, and so it crystallized as a layer around the Cu particles. The thermal conductivity of the samples increased almost linearly with increasing Cu content, but the samples had slightly lower values than the corresponding polyethylene/Cu composites, probably because of the lower thermal conductivity of the wax. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Renewable elastomers based on blends of maleated polypropylene and plasticized starch
Authors: DeLeo Candice , Goetz James , Young Brian , Velankar Sachin S.
Published: January 2010

Most recent developments in polymers from renewable resources have focused on thermoplastics, whereas there has been no comparable development of plastics with elastomeric properties. Here we evaluate the possibility of developing renewable elastomers based on starch. Potato starch plasticized with glycerol (called plasticized starch, or PLS) was melt‐blended with small quantities (5 wt % or 15 wt%) of maleated polypropylene (MAPP). The maleic anhydride groups of the polypropylene are expected to react with the hydroxy groups of starch under melt blending conditions. The resulting blends of MAPP and PLS were characterized by mechanical testing, SEM, DMA, and DSC. SEM, solubility and adhesion tests indicate that the blends are two‐phase materials, in which the continuous phase PLS is physically crosslinked by polypropylene domains. The materials showed rubbery properties as judged by a low glass transition temperature (∼−50°C independent of polypropylene content), and a wide rubbery plateau in DMA experiments that extended from room temperature to as high as 170°C. The tensile properties are also characteristic of elastomers. However, slow aging due to starch crystallization, and extraction of glycerol upon water exposure remain two challenges that must be overcome before the materials can be used as practical elastomers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and properties of carbon fiber/ hydroxyapatite‐poly(methyl methacrylate) biocomposites
Authors: Jianfeng Huang , Juanying Li , Liyun Cao , Liping Zeng
Published: January 2010

An in situ polymerization with a later solution co‐mixing approach was used in the preparation of polymethyl methacrylate (PMMA) matrix composites using hydroxyapatite (HA) nanoparticles and short carbon fibers(C(f)) as reinforcing materials. The microstructures and fracture surface morphologies of the prepared C(f)/HA‐PMMA composite were characterized using XRD, FTIR, SEM, EDS, and FESEM analyses. The mechanical properties of the composites were tested by a universal testing machine. Results show that the surface of nitric acid‐oxidized carbon fibers and lecithin‐treated HA contain new functional groups. Uniform dispersion of short fibers and HA nanoparticles in PMMA matrix is successfully achieved and the mechanical properties of the composites are obviously improved. The flexural strength, flexural modulus, and Young's modulus of the composites reach the maximum value 128.12 MPa, 1.150 GPa, and 4.572 GPa when carbon fiber and HA mass fraction arrive to 4% and 8%, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Relating microhardness to injection molding induced morphology: A study of microbeam synchrotron WAXD
Authors: Kobayashi Yutaka , Kanno Hiroaki , Hanamoto Yasuhiro , Ando Makoto , Kanai Toshitaka
Published: January 2010

The relationship between microhardness and morphology of polypropylene near the surface of injection molded plaques was investigated. Crystal structures and molecular orientation from the surface to shear oriented layer were characterized by microbeam synchrotron wide angle X‐ray diffraction, polarizing optical microscope and Fourier transformed infrared spectroscopy. From precise measurements, using an X‐ray beam with width of 0.35 μm, the frozen layer was divided into two layers. Molecular and crystal orientations changed greatly in the surface layer but remained constant in the inner layer. These oriented morphology did not affect microhardness along the depth direction on the cross‐cut surface. Microhardness was proportional to crystallinity and showed a local maximum at shear oriented layer and a minimum at the surface. Then, positional dependence of microhardness was compared at the gate and the center of the plaque. Although crystallinity near the gate was lower than that at the center position, microhardness was higher. Therefore, crystallinity mainly affects microhardness but superstructure like cross‐hatching lamellae which is induced in biaxially extended melt flow is also not neglected in injection molded polypropylene parts. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Photoisomerization behavior of bisbenzylidene and 1,3,4‐oxadiazole‐based liquid crystalline polyesters
Authors: Balamurugan R. , Kannan P.
Published: January 2010

Photoisomerization behavior of bisbenzylideneacetone/cycloheptanone and 1,3,4‐oxadiazole containing nematic liquid crystalline polyesters under UV irradiation was investigated. Solubility, carbonyl group absorption band in FTIR, optical microscopy observation, as well as DSC analysis through existence of liquid crystallinity after irradiation were proved this phenomenon. Fluorescence spectra revealed blue‐emission maxima with Stokes shift in the range of 46–49 nm. Band gap energy calculated from absorption spectra are in the range of 3.18–3.41 eV. Structure–property relationships were probed by correlating the spacer length with development of mesophase formation, thermal, and optical properties. Optical property of polymers disclosed photoisomerization processes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Statistical thermal stability of PVC
Authors: Savrık Sevdiye Atakul , Erdoğan Beyhan Cansever , Balköse Devrim , Ülkü Semra
Published: January 2010

Experimental design was used to optimize the processing parameters for the decomposition of poly(vinyl chloride). Factorial design and face centered composite design (FCC) were applied to determine the optimum conditions. A total of 10 g PVC powder was mixed with different amounts of zinc stearate (ZnSt2) and natural zeolite and tested for thermal stability. Factorial fitted model was explained by first order pattern due to the significant main effect regression constants, and FCC model was described by second order model owing to higher order polynomial coefficients. FCC design was superior to factorial design as FCC considers not only its pure quadratic effects contribution but also its higher overall desirability for thermal stability of PVC. For factorial design the optimum conditions were determined as 163.06 mg for ZnSt2, 399.99 mg for zeolite, and 140°C for temperature with desirability of 0.933. However, 400 mg for ZnSt2, 333.24 mg for zeolite, and 140°C for temperature with desirability of 0.956 were obtained as the optimum conditions by FCC design. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
5‐Stabilized Phosphatidylinositol 3,4,5‐Trisphosphate Analogues Bind Grp1 PH, Inhibit Phosphoinositide Phosphatases, and Block Neutrophil Migration
Authors: Zhang Honglu , He Ju , Kutateladze Tatiana G. , Sakai Takahiro , Sasaki Takehiko , Markadieu Nicolas , Erneux Christophe , Prestwich Glenn D.
Published: January 2010

Metabolically stabilized analogues of PtdIns(3,4,5)P3 have shown long‐lived agonist activity for cellular events and selective inhibition of lipid phosphatase activity. We describe an efficient asymmetric synthesis of two 5‐phosphatase‐resistant analogues of PtdIns(3,4,5)P3, the 5‐methylene phosphonate (MP) and 5‐phosphorothioate (PT). Furthermore, we illustrate the biochemical and biological activities of five stabilized PtdIns(3,4,5)P3 analogues in four contexts. First, the relative binding affinities of the 3‐MP, 3‐PT, 5‐MP, 5‐PT, and 3,4,5‐PT3 analogues to the Grp1 PH domain are shown, as determined by NMR spectroscopy. Second, the enzymology of the five analogues is explored, showing the relative efficiency of inhibition of SHIP1, SHIP2, and phosphatase and tensin homologue deleted on chromosome 10 (PTEN), as well as the greatly reduced ability of these phosphatases to process these analogues as substrates as compared to PtdIns(3,4,5)P3. Third, exogenously delivered analogues severely impair complement factor C5a‐mediated polarization and migration of murine neutrophils. Finally, the new analogues show long‐lived agonist activity in mimicking insulin action in sodium transport in A6 cells.
Selective Palladium‐Catalyzed Dehydrogenation of Limonene to Dimethylstyrene
Authors: Horrillo‐Martínez Patricia , Virolleaud Marie‐Alice , Jaekel Christoph
Published: January 2010

Conditions for the selective dehydrogenation of (+)‐limonene 1 to the polymer building block dimethylstyrene 2 are described. The reaction occurs smoothly in the presence of Pd(OTFA)2 as catalyst and CuCl2 as oxidant. High selectivity for retaining the exocyclic double bond during aromatization is achieved (>14:1). Initially, variable‐temperature NMR experiments, under stoichiometric conditions, showed a stepwise formation of a π‐allyl intermediate and subsequent reaction to give a mixture of products. However, kinetic experiments showed a sigmoidal curve, pointing to the heterogeneous nature of the catalytically active species. A number of experiments were undertaken to differentiate between homogeneous, molecularly defined catalysis and heterogeneous, nanocluster‐based catalysis. Based on the results, it is proposed that the true catalytic system is heterogeneous in nature.
Influence of Support Hydroxides on the Catalytic Activity of Oxidized Gold Clusters
Authors: Veith Gabriel M. , Lupini Andrew R. , Pennycook Stephen J. , Dudney Nancy J.
Published: January 2010

Gold oxide nanoparticles were prepared on the native surface and a hydroxylated surface of a nonporous TiO2 support (Degussa P25). Scanning transmission electron microscopy shows the formation of similarly sized clusters on both support materials (1.86 and 1.61 nm clusters on the native oxide and the hydroxylated oxide respectively). X‐ray absorption near‐edge spectroscopy and X‐ray photoelectron spectroscopy clearly indicate the formation of Au3+‐rich oxide nanoparticles. Despite the similar cluster sizes and oxidation states, the gold oxide clusters grown on the hydroxylated surface were at least 180 times more catalytically active for the oxidation of carbon monoxide than those grown on the native oxide surface. Thus hydroxides, which are incidentally introduced during the solution‐phase synthesis of gold catalysts, appear to play a dominant, but previously largely unrecognized, role in the catalytic properties of both oxidized and metallic gold particles.
ChemInform Abstract: Synthesis of cis‐Vinyltrimethylstannanes and cis‐Vinylpinacolboronates in a Two‐Step Highly Regio and Stereoselective Process.
Authors: Mirzayans Paul Malek , Pouwer Rebecca H. , Williams Craig M. , Bernhardt Paul V.
Published: January 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Conomicidines A and B, Unusual Alkaloid—Hydroxycinnamyl Alcohol Conjugates from Tabernaemontana corymbosa
Authors: Lim Kuan‐Hon , Kam Toh‐Seok
Published: January 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Raman Spectroscopy of Strained Single‐Walled Carbon Nanotubes
Authors: Liu Zhongfan , Zhang Jin , Gao Bo
Published: January 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Functional Genomics for Plant Natural Product Biosynthesis
Authors: Yonekura‐Sakakibara Keiko , Saito Kazuki
Published: January 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Two‐Dimensional Infrared Spectroscopy of Metal Carbonyls
Authors: Baiz Carlos R. , Mcrobbie Porscha L. , Anna Jessica M. , Geva Eitan , Kubarych Kevin J.
Published: January 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Space‐time cluster identification in point processes
Authors: Assunçäo Renato , Tavares Andréa , Correa Thais , Kulldorff Martin
Published: January 2010

The authors propose a new type of scan statistic to test for the presence of space‐time clusters in point processes data, when the goal is to identify and evaluate the statistical significance of localized clusters. Their method is based only on point patterns for cases; it does not require any specific knowledge of the underlying population. The authors propose to scan the three‐dimensional space with a score test statistic under the null hypothesis that the underlying point process is an inhomogeneous Poisson point process with space and time separable intensity. The alternative is that there are one or more localized space‐time clusters. Their method has been implemented in a computationally efficient way so that it can be applied routinely. They illustrate their method with space‐time crime data from Belo Horizonte, a Brazilian city, in addition to presenting a Monte Carlo study to analyze the power of their new test.
A new family of random graphs for testing spatial segregation
Authors: Ceyhan Elvan , Priebe Carey E. , Marchette David J.
Published: January 2010

The authors discuss a graph‐based approach for testing spatial point patterns. This approach falls under the category of data‐random graphs, which have been introduced and used for statistical pattern recognition in recent years. The authors address specifically the problem of testing complete spatial randomness against spatial patterns of segregation or association between two or more classes of points on the plane. To this end, they use a particular type of parameterized random digraph called a proximity catch digraph (PCD) which is based on relative positions of the data points from various classes. The statistic employed is the relative density of the PCD, which is a U‐statistic when scaled properly. The authors derive the limiting distribution of the relative density, using the standard asymptotic theory of U‐statistics. They evaluate the finite‐sample performance of their test statistic by Monte Carlo simulations and assess its asymptotic performance via Pitman's asymptotic efficiency, thereby yielding the optimal parameters for testing. They further stress that their methodology remains valid for data in higher dimensions.
Marginalized transition random effect models for multivariate longitudinal binary data
Authors: Ilk Ozlem , Daniels Michael J.
Published: January 2010

Generalized linear models with random effects and/or serial dependence are commonly used to analyze longitudinal data. However, the computation and interpretation of marginal covariate effects can be difficult. This led Heagerty (1999, 2002) to propose models for longitudinal binary data in which a logistic regression is first used to explain the average marginal response. The model is then completed by introducing a conditional regression that allows for the longitudinal, within‐subject, dependence, either via random effects or regressing on previous responses. In this paper, the authors extend the work of Heagerty to handle multivariate longitudinal binary response data using a triple of regression models that directly model the marginal mean response while taking into account dependence across time and across responses. Markov Chain Monte Carlo methods are used for inference. Data from the Iowa Youth and Families Project are used to illustrate the methods.
Cramér‐von Mises statistics for discrete distributions with unknown parameters
Authors: Lockhart Richard A. , Spinelli John J. , Stephens Michael A.
Published: January 2010

Choulakian, Lockhart & Stephens (1994) proposed Cramér‐von Mises statistics for testing fit to a fully specified discrete distribution. The authors give slightly modified definitions for these statistics and determine their asymptotic behaviour in the case when unknown parameters in the distribution must be estimated from the sample data. They also present two examples of applications.
Bayesian analysis of elapsed times in continuous‐time Markov chains
Authors: Ferreira Marco A. R. , Suchard Marc A.
Published: January 2010

The authors consider Bayesian analysis for continuous‐time Markov chain models based on a conditional reference prior. For such models, inference of the elapsed time between chain observations depends heavily on the rate of decay of the prior as the elapsed time increases. Moreover, improper priors on the elapsed time may lead to improper posterior distributions. In addition, an infinitesimal rate matrix also characterizes this class of models. Experts often have good prior knowledge about the parameters of this matrix. The authors show that the use of a proper prior for the rate matrix parameters together with the conditional reference prior for the elapsed time yields a proper posterior distribution. The authors also demonstrate that, when compared to analyses based on priors previously proposed in the literature, a Bayesian analysis on the elapsed time based on the conditional reference prior possesses better frequentist properties. The type of prior thus represents a better default prior choice for estimation software.
Empirical likelihood inference for the regression model of mean quality‐adjusted lifetime with censored data
Authors: Zhao Yichuan , Wang Hongkun
Published: January 2010

The authors consider the empirical likelihood method for the regression model of mean quality‐adjusted lifetime with right censoring. They show that an empirical log‐likelihood ratio for the vector of the regression parameters is asymptotically a weighted sum of independent chi‐squared random variables. They adjust this empirical log‐likelihood ratio so that the limiting distribution is a standard chi‐square and construct corresponding confidence regions. Simulation studies lead them to conclude that empirical likelihood methods outperform the normal approximation methods in terms of coverage probability. They illustrate their methods with a data example from a breast cancer clinical trial study.
Optimal scaling of Metropolis algorithms: Heading toward general target distributions
Authors: Bédard Mylène , Rosenthal Jeffrey S.
Published: January 2010

The authors provide an overview of optimal scaling results for the Metropolis algorithm with Gaussian proposal distribution. They address in more depth the case of high‐dimensional target distributions formed of independent, but not identically distributed components. They attempt to give an intuitive explanation as to why the well‐known optimal acceptance rate of 0.234 is not always suitable. They show how to find the asymptotically optimal acceptance rate when needed, and they explain why it is sometimes necessary to turn to inhomogeneous proposal distributions. Their results are illustrated with a simple example.
On probability matching priors
Authors: Staicu Ana‐Maria , Reid Nancy M.
Published: January 2010

First‐order probability matching priors are priors for which Bayesian and frequentist inference, in the form of posterior quantiles, or confidence intervals, agree to a second order of approximation. The authors show that the matching priors developed by Peers (1965) and Tibshirani (1989) are readily and uniquely implemented in a third‐order approximation to the posterior marginal density. The authors further show how strong orthogonality of parameters simplifies the arguments. Several examples illustrate their results.
Clinical impact of phosphorylated signal transducer and activator of transcription 3, epidermal growth factor receptor, p53, and vascular endothelial growth factor receptor 1 expression in resected adenocarcinoma of lung by using tissue microarray
Authors: Kim Hyeong Su , Park Yeon Hee , Lee Jeeyun , Ahn Jin‐Seok , Kim Jinkook , Shim Young Mog , Kim Jung Han , Park Keunchil , Han Joungho , Ahn Myung‐Ju
Published: January 2010

BACKGROUND:

The signal transducer and activator of transcription 3 (STAT3) play a key role in the downstream pathway of the epidermal growth factor receptor (EGFR) in nonsmall cell lung cancer and promote cell proliferation, invasion, and angiogenesis. The clinical significance of phosphorylated STAT3 (pSTAT3), EGFR, p53, and vascular endothelial growth factor receptor 1 (VEGFR‐1) expression in patients with completely resected lung adenocarcinoma was evaluated to determine the effects of pSTAT3 in tumor angiogenesis and proliferation.

METHODS:

The expressions of pSTAT3, EGFR, p53, and VEGFR‐1 were evaluated by immunohistochemical staining of tissue microarrays from 162 samples of resected lung adenocarcinoma.

RESULTS:

The median age of the 162 patients was 62 years, the median disease‐free survival was 41.7 months, and the median OS (OS) was 80.2 months. Expression of pSTAT3, EGFR, p53, and VEGFR‐1 was detected in 51.2%, 71%, 35.2%, and 35.2% of the samples, respectively. pSTAT3 expression was correlated significantly with VEGFR‐1 expression (P = .025). The coexpression of pSTAT3 and VEGFR‐1 was correlated with increased lymph node involvement (P = .021) and a trend toward a short OS (P = .085). In multivariate analysis, the expression levels of p53 and VEGFR‐1 were identified as independent prognostic factors that affected OS.

CONCLUSIONS:

The results of this study suggested that pSTAT3 and VEGFR‐1 expression may play roles in the tumor progression and angiogenesis of lung adenocarcinoma. Further studies are needed, however, to uncover the detailed mechanisms that underlie the roles of these proteins in lung adenocarcinoma. Cancer 2010. © 2010 American Cancer Society.
Mortality in men with localized prostate cancer treated with brachytherapy with or without neoadjuvant hormone therapy
Authors: Dosoretz Amy M. , Chen Ming‐Hui , Salenius Sharon A. , Ross Rudolf H. , Dosoretz Daniel E. , Katin Michael J. , Mantz Constantine , Nakfoor Bruce M. , D'Amico Anthony V.
Published: January 2010

BACKGROUND:

Discrepancies exist regarding the impact of neoadjuvant hormone therapy (NHT) on the risk of all‐cause mortality (ACM) in men who receive brachytherapy for localized prostate cancer. Therefore, the objective of the current study was to examine the effect of NHT on the risk of ACM in men with prostate cancer who receive with brachytherapy.

METHODS:

The study cohort included 2474 men with localized prostate cancer who either received NHT (N = 1083) or did not receive NHT (N = 1391) and brachytherapy without supplemental external beam radiation between 1991 and 2005 at centers within the 21st Century Oncology Consortium. All men had at least 2 years of follow‐up. Low‐risk, intermediate‐risk, and high‐risk disease was present in 65%, 23%, and 12% of men, respectively. A Cox regression multivariate analysis was used to evaluate the risk of ACM in men who received NHT compared with all others adjusting for age, prostate‐specific antigen level, Gleason score, and tumor classification.

RESULTS:

After a median follow‐up of 4.8 years (interquartile range, 3.3‐7.5 years) and adjusting for known prostate cancer prognostic factors and age, treatment with NHT was associated significantly with an increased risk of ACM (adjusted hazard ratio, 1.24; 95% confidence interval, 1.01‐1.53; P = .04) in men aged ≥73 years. In men who were younger than the median age of 73 years, hormone therapy use was not significant (P = .34).

CONCLUSIONS:

Compared with men who were younger than the median age of 73 years, men aged ≥73 years with localized prostate cancer who received brachytherapy and NHT had an increased risk of ACM compared with men who did not receive NHT. Cancer 2010. © 2010 American Cancer Society.
Perils of quinolone exposure in cancer patients
Authors: Rangaraj Gopi , Granwehr Bruno P. , Jiang Ying , Hachem Ray , Raad Issam
Published: January 2010

BACKGROUND:

The objective of this study was to determine the effect of antibiotic use (including prophylaxis) on the emergence of multidrug‐resistant (MDR) breakthrough bacteremia in cancer patients.

METHODS:

In this retrospective study, the authors identified all bacteremia episodes from July 2005 to December 2006 at their tertiary cancer center and compared the bacteria types and antimicrobial resistance in isolates from patients who had received antimicrobial agents as therapy or prophylaxis (breakthrough infections) with those from patients who had not received antimicrobial agents (nonbreakthrough bacteremia).

RESULTS:

Breakthrough bacteremia was more likely to be associated with MDR Escherichia coli (P = .002), MDR Pseudomonas aeruginosa (P = .02), and vancomycin‐resistant enterococci (P = .01). Multivariate analysis revealed that breakthrough bacteremia was associated with hematologic malignancies and neutropenia (odds ratios, 9.9 and 3.0, respectively). Fluoroquinolone use was associated significantly with the emergence of methicillin‐resistant Staphylococcus aureus (P = .04), MDR E. coli (P < .001), and MDR P. aeruginosa (P = .05). A strong association was observed between fluoroquinolone use and breakthrough bacteremia in multivariate analysis (odds ratio, 22; P < .001). Patients who had received vancomycin were more likely to have vancomycin‐resistant enterococci bloodstream isolates than patients who had not received antibacterial agents (P < .001).

CONCLUSIONS:

Breakthrough infections were more common in neutropenic patients and in patients who had hematologic malignancies. The isolation of MDR organisms was associated strongly with the use of fluoroquinolones. The current findings demonstrated the importance of using a comprehensive approach to the prevention of MDR bacterial infections, including the initiation of antibiotic stewardship programs. Cancer 2010. © 2010 American Cancer Society.
Early 18F‐2‐fluoro‐2‐deoxy‐d‐glucose positron emission tomography may identify a subset of patients with estrogen receptor‐positive breast cancer who will not respond optimally to preoperative chemotherapy
Authors: Martoni Andrea A. , Zamagni Claudio , Quercia Sara , Rosati Marta , Cacciari Nicoletta , Bernardi Alessandra , Musto Alessandra , Fanti Stefano , Santini Donatella , Taffurelli Mario
Published: January 2010

BACKGROUND:

A pathologic complete response (pCR) and minimal residual disease (pMRD) after preoperative chemotherapy (PCT) for early stage or locally advanced breast cancer (BC) correlates with a good prognosis.

METHODS:

Patients who received from 6 to 8 cycles of PCT for BC were monitored by 18F‐2‐fluoro‐2‐deoxy‐D‐glucose positron emission tomography (18F‐FDG‐PET), and the maximal standardized uptake value (SUVmax) was calculated at baseline, after 2 cycles, after 4 cycles, and at the end of PCT. SUVmax percentage changes (Δ‐SUV) were compared with the pathologic response rate. Patients who had a pCR or pMRD in the tumor and an absence of cancer cells in ipsilateral axillary lymph nodes were defined as having obtained an optimal pathologic response (pR), whereas all the other conditions were classified as a pathologic nonresponse (pNR).

RESULTS:

Of 34 patients, 7 (21%) achieved a pR (3 patients had a pCR, and 4 patients had pMRD). After the second cycle, the Δ‐SUV threshold with optimal negative predictive value to predict a pR was 50%. Twenty‐six patients (76%) had a Δ‐SUV >50%, including all 7 patients who had a pR and 19 patients who had a pNR. Conversely, all 8 patients who had a Δ‐SUV ≤50% had a pNR. All 8 of those patients had estrogen recepetor‐positive tumors.

CONCLUSIONS:

Early evaluation of metabolic response by 18F‐FDG‐PET during PCT was able to identify 30% of patients, all with estrogen receptor‐positive tumors, who would not obtain pR after completion of chemotherapy program. Cancer 2010. © 2010 American Cancer Society.
Ultra‐early predictive assay for treatment failure using functional magnetic resonance imaging and clinical prognostic parameters in cervical cancer
Authors: Mayr Nina A. , Yuh William T. C. , Jajoura David , Wang Jian Z. , Lo Simon S. , Montebello Joseph F. , Porter Kyle , Zhang Dongqing , McMeekin D. Scott , Buatti John M.
Published: January 2010

BACKGROUND:

The authors prospectively evaluated magnetic resonance imaging (MRI) parameters quantifying heterogeneous perfusion pattern and residual tumor volume early during treatment in cervical cancer, and compared their predictive power for primary tumor recurrence and cancer death with the standard clinical prognostic factors. A novel approach of augmenting the predictive power of clinical prognostic factors with MRI parameters was assessed.

METHODS:

Sixty‐two cervical cancer patients underwent dynamic contrast‐enhanced (DCE) MRI before and during early radiation/chemotherapy (2‐2.5 weeks into treatment). Heterogeneous tumor perfusion was analyzed by signal intensity (SI) of each tumor voxel. Poorly perfused tumor regions were quantified as lower 10th percentile of SI (SI[10%]). DCE‐MRI and 3‐dimensional (3D) tumor volumetry MRI parameters were assessed as predictors of recurrence and cancer death (median follow‐up, 4.1 years). Their discriminating capacity was compared with clinical prognostic factors (stage, lymph node status, histology) using sensitivity/specificity and Cox regression analysis.

RESULTS:

SI(10%) and 3D volume 2‐2.5 weeks into therapy independently predicted disease recurrence (hazard ratio [HR], 2.6; 95% confidence interval [95% CI], 1.0‐6.5 [P = .04] and HR, 1.9; 95% CI, 1.1‐3.5 [P = .03], respectively) and death (HR, 1.9; 95% CI, 1.0‐3.5 [P = .03] and HR, 1.9; 95% CI, 1.2‐2.9 [P = .01], respectively), and were superior to clinical prognostic factors. The addition of MRI parameters to clinical prognostic factors increased sensitivity and specificity of clinical prognostic factors from 71% and 51%, respectively, to 100% and 71%, respectively, for predicting recurrence, and from 79% and 54%, respectively, to 93% and 60%, respectively, for predicting death.

CONCLUSIONS:

MRI parameters reflecting heterogeneous tumor perfusion and subtle tumor volume change early during radiation/chemotherapy are independent and better predictors of tumor recurrence and death than clinical prognostic factors. The combination of clinical prognostic factors and MRI parameters further improves early prediction of treatment failure and may enable a window of opportunity to alter treatment strategy. Cancer 2010. © 2010 American Cancer Society.
The effects of paclitaxel, dose density, and trastuzumab on treatment‐related amenorrhea in premenopausal women with breast cancer
Authors: Abusief Mary E. , Missmer Stacey A. , Ginsburg Elizabeth S. , Weeks Jane C. , Partridge Ann H.
Published: January 2010

BACKGROUND:

Little information is available regarding the effects of new adjuvant treatment regimens on menstrual functioning in premenopausal women with early breast cancer.

METHODS:

The authors conducted a retrospective review of data from premenopausal women who received treatment for early breast cancer to evaluate the rates of amenorrhea in follow‐up. The women who were included received treatment with either doxorubicin and cyclophosphamide (AC) or combined AC and paclitaxel (T) (AC‐T) given either every 3 weeks, or as a dose‐dense (DD) regimen, or as AC followed by weekly T with trastuzumab or followed by trastuzumab (AC‐T+trastuzumab). A multivariate logistic regression analysis was conducted to evaluate amenorrhea during follow‐up.

RESULTS:

Of 431 patients who were eligible for analysis, the average age at diagnosis was 13 years (range, 25‐55 years), 61% of women received AC only, and 39% received AC‐T. Of the 39% who received AC‐T, 49% of women received DD therapy, 14% received AC‐T+trastuzumab, and 71% of all patients received tamoxifen (TAM). The median follow‐up was 33 months (range, 6‐114 months). After adjusting for age, weight, gravidity, parity, age at menarche, smoking, alcohol use, TAM use, type and regimen of chemotherapy, and use of trastuzumab, the likelihood of remaining amenorrheic was not statistically different in patients who received AC‐T versus AC (odds ratio [OR], 1.59; 95% confidence interval [CI], 0.8‐3.2), DD treatment versus treatment every 3 weeks (OR, 0.56; 95% CI, 0.25‐1.3), or AC‐T + trastuzumab (OR, 0.6; 95% CI, 0.22‐1.61). Amenorrhea was associated significantly with TAM use and age at diagnosis.

CONCLUSIONS:

Recent advances in the adjuvant treatment of early breast cancer do not appear to have increased the risk of amenorrhea in premenopausal women. Cancer 2010. © 2010 American Cancer Society.
Should extrapulmonary small cell cancer be managed like small cell lung cancer?
Authors: Brennan Sinead M. , Gregory Deborah L. , Stillie Alison , Herschtal Alan , Mac Manus Michael , Ball David L.
Published: January 2010

BACKGROUND:

The aim of this study was to determine if extrapulmonary small cell carcinomas (EPSCC) should be managed using protocols similar to those for small cell lung cancer (SCLC).

METHODS:

Treatment strategies, survival, patterns of failure, and prognostic factors for patients with EPSCC were analyzed retrospectively at a large cancer center. SCLC was excluded by thoracic computed tomography (75%) or chest radiography (25%).

RESULTS:

Of 120 eligible patients, 70% had limited disease (LD). Treatment modalities included chemotherapy (n = 82; 68%), radiotherapy (RT) (n = 80; 67%), and surgery (n = 41, 34%). The median survival for patients with LD and extensive disease was 1.4 years and 0.7 years, respectively. Gynecologic (n = 31) and gastrointestinal (n = 28) were the most common primary tumor sites. Gynecologic and head and neck primary tumor sites had better 1‐year survival than other sites (P = .019 and 0.005, respectively). Brain metastasis was the site of first distant failure in 4.1% of patients versus 35% for soft tissue metastases. The lifetime risk of brain metastasis was 13%. Definitive RT (P = .004), LD (P = .028), and prophylactic cranial irradiation (PCI) (P = .022) were found to be positive prognostic factors and weight loss (P < .001) was a negative prognostic factor on multivariate analysis.

CONCLUSIONS:

Patients with EPSCC usually experienced short survival, often with early distant metastasis. Although PCI was associated with improved overall survival, brain metastasis was less frequent than in patients with SCLC, and therefore the potential benefit of PCI was less than in patients with SCLC. Definitive chemoradiotherapy was associated with better outcomes and should be delivered whenever feasible. Cancer 2010. © 2010 American Cancer Society.
Direct Arylation of Imidazo[1,2‐b]pyridazines: Microwave‐Assisted One‐Pot Suzuki Coupling/Pd‐Catalysed Arylation
Authors: El Akkaoui Ahmed , Berteina‐Raboin Sabine , Mouaddib Abderrahim , Guillaumet Gérald
Published: January 2010

Direct intermolecular C–H arylation of 6‐chloroimidazo[1,2‐b]pyridazine in its 3‐position was achieved, and the tolerance to reaction conditions in the presence of chloro groups was investigated. Various 3‐(hetero)arylimidazo[1,2‐b]pyridazines were synthesized in good to excellent yields. This methodology was successfully applied to the synthesis of 3,6‐di‐ and 2,3,6‐trisubstituted imidazo[1,2‐b]pyridazines by a microwave‐assisted, one‐pot, two‐step Suzuki cross‐coupling/palladium‐catalysed arylation process.