bluuebunny/crossref_metadata_2025 huggingface dataset:
Importance of MS selectivity and chromatographic separation in LC‐MS/MS‐based methods when investigating pharmaceutical metabolites in water. Dipyrone as a case of study
Authors: Ibáñez M. , Gracia‐Lor E. , Sancho J. V. , Hernández F.
Published: August 2012

Pharmaceuticals are emerging contaminants of increasing concern because of their presence in the aquatic environment and potential to reach drinking‐water sources. After human and/or veterinary consumption, pharmaceuticals can be excreted in unchanged form, as the parent compound, and/or as free or conjugated metabolites. Determination of most pharmaceuticals and metabolites in the environment is commonly made by liquid chromatography (LC) coupled to mass spectrometry (MS). LC coupled to tandem MS is the technique of choice nowadays in this field. The acquisition of two selected reaction monitoring (SRM) transitions together with the retention time is the most widely accepted criterion for a safe quantification and confirmation assay. However, scarce attention is normally paid to the selectivity of the selected transitions as well as to the chromatographic separation. In this work, the importance of full spectrum acquisition high‐resolution MS data using a hybrid quadrupole time‐of‐flight analyser and/or a suitable chromatographic separation (to reduce the possibility of co‐eluting interferences) is highlighted when investigating pharmaceutical metabolites that share common fragment ions. For this purpose, the analytical challenge associated to the determination of metabolites of the widely used analgesic dipyrone (also known as metamizol) in urban wastewater is discussed. Examples are given on the possibilities of reporting false positives of dypirone metabolites by LC‐MS/MS under SRM mode due to a wrong assignment of identity of the compounds detected. Copyright © 2012 John Wiley & Sons, Ltd.
Critical parameters for the analysis of anionic oligosaccharides by desorption electrospray ionization mass spectrometry
Authors: Przybylski Cédric , Gonnet Florence , Buchmann William , Daniel Régis
Published: August 2012

Sulfated oligosaccharides derived from glycosaminoglycans (GAGs) are fragile compounds, highly polar and anionic. We report here on the rare but successful application of desorption electrospray ionization (DESI) — LTQ‐Orbitrap mass spectrometry (MS) to the high‐resolution analysis of anionic and sulfated oligosaccharides derived from the GAGs hyaluronic acid and heparin. For that purpose, key parameters affecting DESI performance, comprising the geometric parameters of the DESI source, the probed surface and the spraying conditions, applied spray voltage, flow rates and solvent composition were investigated. Under suitable conditions, the DESI technique allows the preservation of the structural integrity of such fragile compounds. DESI enabled the sensitive detection of anionic hyaluronic acid and heparin oligosaccharides with a limit of detection (LOD) down to 5 fmol (≈10 pg) for the hyaluronic acid decasaccharide. Detection of hyaluronic acid oligosaccharides in urine sample was also successfully achieved with LOD values inferior to the ng range. Multistage tandem mass spectrometry (MSn) through the combination of the DESI source with a hybrid linear ion trap‐orbitrap mass spectrometer allowed the discrimination of isomeric sulfated oligosaccharides and the sequence determination of a hyaluronic acid decasaccharide. These results open promising ways in glycomic and glycobiology fields where structure–activity relationships of bioactive carbohydrates are currently questioned. Copyright © 2012 John Wiley & Sons, Ltd.
Application of high‐resolution ESI and MALDI mass spectrometry to metabolite profiling of small interfering RNA duplex
Authors: Shimizu Hisao , Jinno Fumihiro , Morohashi Akio , Yamazaki Yuzo , Yamada Masaki , Kondo Takahiro , Asahi Satoru
Published: August 2012

We investigated the application of a high‐resolution Orbitrap mass spectrometer equipped with an electrospray ionization (ESI) source and a matrix‐assisted laser desorption/ionization‐time‐of‐flight (MALDI‐TOF) mass spectrometer to the metabolite profiling of a model small interfering RNA (siRNA) duplex TSR#34 and compared their functions and capabilities. TSR#34 duplex was incubated in human serum in vitro, and the duplex and its metabolites were then purified by ion exchange chromatography in order to remove the biological matrices. The fraction containing the siRNA duplex and its metabolites was collected and desalted and then subjected to high‐performance liquid chromatography (HPLC) equipped with a reversed phase column. The siRNA and its metabolites were separated into single strands by elevated chromatographic temperature and analyzed using the ESI‐Orbitrap or the MALDI‐TOF mass spectrometer. Using this method, the 5' and/or 3' truncated metabolites of each strand were detected in the human serum samples. The ESI‐Orbitrap mass spectrometer enabled differentiation between two possible RNA‐based sequences, a monoisotopic molecular mass difference which was less than 2 Da, with an intrinsic mass resolving power. In‐source decay (ISD) analysis using a MALDI‐TOF mass spectrometer allowed the sequencing of the RNA metabolite with characteristic fragment ions, using 2,4‐dihydroxyacetophenone (2,4‐DHAP) as a matrix. The ESI‐Orbitrap mass spectrometer provided the highest mass accuracy and the benefit of on‐line coupling with HPLC for metabolite profiling. Meanwhile, the MALDI‐TOF mass spectrometer, in combination with 2,4‐DHAP, has the potential for the sequencing of RNA by ISD analysis. The combined use of these methods will be beneficial to characterize the metabolites of therapeutic siRNA compounds. Copyright © 2012 John Wiley & Sons, Ltd.
Gas phase retro‐Michael reaction resulting from dissociative protonation: fragmentation of protonated warfarin in mass spectrometry
Authors: Zhang Jia , Chai Yunfeng , Jiang Kezhi , Yang Huameng , Pan Yuanjiang , Sun Cuirong
Published: August 2012

A mass spectrometric study of protonated warfarin and its derivatives (compounds 1 to 5) has been performed. Losses of a substituted benzylideneacetone and a 4‐hydroxycoumarin have been observed as a result of retro‐Michael reaction. The added proton is initially localized between the two carbonyl oxygens through hydrogen bonding in the most thermodynamically favorable tautomer. Upon collisional activation, the added proton migrates to the C‐3 of 4‐hydroxycoumarin, which is called the dissociative protonation site, leading to the formation of the intermediate ion‐neutral complex (INC). Within the INC, further proton transfer gives rise to a proton‐bound complex. The cleavage of one hydrogen bond of the proton‐bound complex produces the protonated 4‐hydroxycoumarin, while the separation of the other hydrogen bond gives rise to the protonated benzylideneacetone. Theoretical calculations indicate that the 1, 5‐proton transfer pathway is most thermodynamically favorable and support the existence of the INC. Both substituent effect and the kinetic method were utilized for explaining the relative abundances of protonated 4‐hydroxycoumarin and protonated benzylideneacetone derivative. For monosubstituted warfarins, the electron‐donating substituents favor the generation of protonated substituted benzylideneacetone, whereas the electron‐withdrawing groups favor the formation of protonated 4‐hydroxycoumarin. Copyright © 2012 John Wiley & Sons, Ltd.
Full utilization of a mass spectrometer using on‐demand sharing with multiple LC units
Authors: Li Shu , Hao Qin , Gounarides John , Wang Y. Karen
Published: August 2012

The applicability of liquid chromatography–mass spectrometry (LC/MS) is often limited by throughput. The sharing of a mass spectrometer with multiple LCs significantly improves throughput; however, the reported systems have not been designed to fully utilize the MS duty cycle, and as a result to achieve maximum throughput. To fully utilize the mass spectrometer, the number of LC units that a MS will need to recruit is application dependent and could be significantly larger than the current commercial or published implementations. For the example of a single analyte, the number may approach the peak capacity to a first degree approximation. Here, the construction of a MS system that flexibly recruits any number of LC units demanded by the application is discussed, followed by the method to port a previously developed LC/MS method to the system to fully utilize a mass spectrometer. To demonstrate the performance and operation, a prototypical MS system of eight LC units was constructed. When 1‐min chromatographic separations were performed in parallel on the eight LCs of the system, the average LC/MS analysis time per sample was 10.5 s when applied to the analysis of samples in 384‐well plate format. This system has been successfully used to conduct large‐volume biochemical assays with the analysis of a variety of molecular entities in support of drug discovery efforts. Allowing the recruitment of the number of LC units appropriate for a given application, this system has the potential to be a plug‐and‐play system to fully utilize a mass spectrometer. Copyright © 2012 John Wiley & Sons, Ltd.
Minimally invasive surgery for gastric cancer
Authors: Bamboat Zubin M. , Strong Vivian E.
Published: August 2012

Application of minimally invasive techniques to gastric cancer in the West has been curbed by concerns of feasibility and oncologic adequacy. Growing evidence supports improved short‐term and equivalent oncologic outcomes in selected patients undergoing laparoscopic surgery for early‐stage disease. Laparoscopic resection for advanced gastric cancer remains controversial due to few reliable studies on long‐term outcomes. We focus on important studies from Asia and highlight the Western experience with laparoscopic and robotic surgery for gastric carcinoma. J. Surg. Oncol. 2013;107:271–276. © 2012 Wiley Periodicals, Inc.
A reversal in the vascularity of metastatic liver tumors from colorectal cancer after the cessation of chemotherapy plus bevacizumab: Contrast‐enhanced ultrasonography and histological examination
Authors: Kitamura Hiroshi , Koike Shoichiro , Nakazawa Koh , Matsumura Hideyasu , Yokoi Kenta , Nakagawa Kan , Arai Masayuki
Published: August 2012

Objective

To assess the effect of chemotherapy plus bevacizumab on tumor vessels, as well as the reversibility of this effect, using contrast‐enhanced ultrasonography (CEUS) and histology in patients with metastatic liver tumors derived from colorectal cancer.

Methods

The study included 12 patients who received chemotherapy plus bevacizumab, experienced a reduction in tumor vascularity as demonstrated by CEUS and consequently underwent liver resection. CEUS was performed before and after four courses of chemotherapy and before surgery. The numbers of microvessels highlighted by anti‐CD34 antibodies in the viable tumor tissue were counted to quantify the microvessel density (MVD). As a control, 12 surgical specimens from 12 patients who had not received chemotherapy were examined.

Results

A reversal of tumor vascularity was observed in 10 of 12 patients. In two patients, the vascularity remained reduced. The MVD in the treatment group was significantly lower than that observed in the group without treatment.

Conclusion

The data suggest that the tumor vessels regenerated substantially, although the effect of chemotherapy plus bevacizumab remained weak for approximately 6 weeks after the cessation of treatment. Therefore, future research must determine whether bevacizumab should be used prior to surgery. J. Surg. Oncol. 2013;107:155–159. © 2012 Wiley Periodicals, Inc.
Resection of large hepatocellular carcinoma (≥10 cm): A unique western perspective
Authors: Shrager Brian , Jibara Ghalib A. , Tabrizian Parissa , Schwartz Myron E. , Labow Daniel M. , Hiotis Spiros
Published: August 2012

Background and Objectives

Few Western centers have surgically treated a high volume of large hepatocellular carcinoma 10 cm or more in diameter. The study aim was to analyze a large Western cohort of these patients, and to present our outcomes in the context of the more extensive Eastern experience.

Methods

We retrospectively reviewed all patients at our center receiving partial hepatectomy from January 1992 to August 2010, and analyzed a cohort with hepatocellular carcinoma ≥10 cm in diameter.

Results

One hundred thirty patients comprised the cohort. One hundred three (79.2%) of the patients received major anatomic resections, and 23 (17.7%) patients underwent tumor thrombectomy as an adjunct procedure. Perioperative mortality was observed in 9 (6.9%) of cases, but from January 2002 onward, only 2 (2.3%) of the 86 resections performed resulted in a mortality. The survival rate at 1, 3, and 5 years was 56.9%, 30.3%, and 18.8%, respectively; the median survival was 17.0 months. The subgroup of 39 patients without gross vascular invasion and satellite nodules achieved a median survival of 40.3 months.

Conclusions

Resection of large hepatocellular carcinoma can be done with safety at a large Western center, and a subgroup of patients will achieve long‐term survival. J. Surg. Oncol. 2013;107:111–117. © 2012 Wiley Periodicals, Inc.
Quantum design strategy pushes high‐power vertical‐external‐cavity surface‐emitting lasers beyond 100 W
Authors: Wang T.‐L. , Heinen B. , Hader J. , Dineen C. , Sparenberg M. , Weber A. , Kunert B. , Koch S.W. , Moloney J.V. , Koch M. , Stolz W.
Published: August 2012

Combining rigorous quantum epitaxial design, highly accurate growth, novel processing and thermal management pushes the output power of single chip vertical‐external‐cavity surface‐emitting lasers (VECSELs) beyond the 100 W milestone.
Cosmologies of Capability, Markets and Wisdom of Crowds: Introduction and Comparative Agenda
Authors: Felin Teppo
Published: August 2012

The ability—or ‘capability’—to do something has much to do with the nature of the individuals involved and the aggregate and emergent outcomes of their interactions. I focus on the endogenous origins of capability in organizations and markets, in response to cosmologies of capability and organization that focus on the exogenous environment (selection or external categories), behavioral learning and related mechanisms (association or analogy). I look at capabilities comparatively—across forms, contexts and even species—and discuss their aggregate, emergent nature. I introduce the special issue papers and discuss a broader agenda on endogenous capabilities, aggregation and comparative organization. Copyright © 2012 John Wiley & Sons, Ltd.
Screening test for malignant hyperthermia in patients with persistent hyperCKemia: A pilot study
Authors: Johannsen Stephan , Berberich Christina , Metterlein Thomas , Roth Cosima , Reiners Karlheinz , Roewer Norbert , Schuster Frank
Published: August 2012

Introduction: Persistently elevated serum creatine kinase (CK) is frequently associated with predisposition to malignant hyperthermia (MH). We investigated whether a minimally invasive metabolic test is suitable to diagnose MH susceptibility among patients with hyperCKemia. Methods: Thirty‐nine participants were included: 10 were MH susceptible (MHS); 21 MH were non‐susceptible (MHN); and 8 had MHN with persistent hyperCKemia >500 U/L. Microdialysis probes were inserted into the vastus lateralis muscle, and halothane or caffeine was injected via an attached microtubing catheter. Lactate concentrations in dialysis samples were measured spectrophotometrically. Results: Baseline lactate did not differ between the groups. After local application of halothane or caffeine, a significant lactate increase was detected only in the MHS group. Conclusions: Test results were not influenced by hyperCKemia. To avoid risks and complications of a surgical muscle biopsy this microdialysis test might be a useful screening tool for MH susceptibility among patients with persistent CK elevation. Muscle Nerve 47: 677–681, 2013
Parametric inference for component distributions from lifetimes of systems with dependent components
Authors: Navarro Jorge , Ng Hon Keung Tony , Balakrishnan Narayanaswamy
Published: August 2012

In system reliability analysis, for an n ‐component system, the estimation of the performance of the components in the system is not straightforward in practice, especially when the components are dependent. Here, by assuming the n components in the system to be identically distributed with a common distribution belonging to a scale‐family and the dependence structure between the components being known, we discuss the estimation of the lifetime distributions of the components in the system based on the lifetimes of systems with the same structure. We develop a general framework for inference on the scale parameter of the component lifetime distribution. Specifically, the method of moments estimator (MME) and the maximum likelihood estimator (MLE) are derived for the scale parameter, and the conditions for the existence of the MLE are also discussed. The asymptotic confidence intervals for the scale parameter are also developed based on the MME and the MLE. General simulation procedures for the system lifetime under this model are described. Finally, some examples of two‐ and three‐component systems are presented to illustrate all the inferential procedures developed here. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012
Adaptive mesh refinement and coarsening for cohesive zone modeling of dynamic fracture
Authors: Park Kyoungsoo , Paulino Glaucio H. , Celes Waldemar , Espinha Rodrigo
Published: August 2012

Adaptive mesh refinement and coarsening schemes are proposed for efficient computational simulation of dynamic cohesive fracture. The adaptive mesh refinement consists of a sequence of edge‐split operators, whereas the adaptive mesh coarsening is based on a sequence of vertex‐removal (or edge‐collapse) operators. Nodal perturbation and edge‐swap operators are also employed around the crack tip region to improve crack geometry representation, and cohesive surface elements are adaptively inserted whenever and wherever they are needed by means of an extrinsic cohesive zone model approach. Such adaptive mesh modification events are maintained in conjunction with a topological data structure (TopS). The so‐called PPR potential‐based cohesive model (J. Mech. Phys. Solids 2009; 57:891–908) is utilized for the constitutive relationship of the cohesive zone model. The examples investigated include mode I fracture, mixed‐mode fracture and crack branching problems. The computational results using mesh adaptivity (refinement and coarsening) are consistent with the results using uniform mesh refinement. The present approach significantly reduces computational cost while exhibiting a multiscale effect that captures both global macro‐crack and local micro‐cracks. Copyright © 2012 John Wiley & Sons, Ltd.
Influenza vaccine safety in pregnancy: can we identify exposures?
Authors: Louik Carol , Chambers Christina , Jacobs Dawn , Rice Fiona , Johnson Diana , Mitchell Allen A.
Published: August 2012

Purpose

To assess the feasibility of identifying influenza vaccine exposure in pregnancy.

Methods

Two study designs were used. (i) Women who contacted the Organization of Teratology Information Specialists (OTIS) network and were referred to their research center or contacted the center directly were invited to participate. (ii) Vaccine exposure information was gathered within an ongoing case–control surveillance program, the Slone Birth Defects Study (BDS).

To confirm vaccine exposure and obtain details (e.g., brand name, presence of thimerosal), we requested medical records. If records were not available, we contacted the provider for information regarding the vaccine product used in that setting. If the provider used only one vaccine product during the reported exposure period, we assumed those vaccine details applied to the reported exposure. Otherwise, no details could be inferred.

Results

Between September 2006 and February 2008, OTIS enrolled 106 women who reported influenza vaccine exposure during pregnancy. Vaccine was confirmed for 100 (94.3%); brand was confirmed for 87 (82.1%). Among 2177 BDS interviews completed during the same period, 462 (20.8%) reported influenza vaccine exposure; brand and formulation were available for 314 (69.5%). Over one quarter of the BDS women (29%) received their vaccine in nontraditional settings, where influenza vaccine exposure would not likely be recorded in their medical record.

Conclusions

We demonstrated the capacity both to identify influenza vaccine exposure in pregnancy and to obtain important details of the specific vaccine administered. Many women receive influenza vaccines outside of typical health care settings, which has important implications for influenza vaccine studies that rely on medical records. Copyright © 2012 John Wiley & Sons, Ltd.
PEG‐b‐PtBA‐b‐PHEMA well‐defined amphiphilic triblock copolymer: Synthesis, self‐assembly, and application in drug delivery
Authors: Yuan Li , Chen Wulian , Li Jing , Hu Jianhua , Yan Jianjun , Yang Dong
Published: August 2012

A series of well‐defined amphiphilic triblock copolymers, poly(ethylene glycol)‐b‐poly(tert‐butyl acrylate)‐b‐poly(2‐hydroxyethyl methacrylate) (PEG‐b‐PtBA‐b‐PHEMA), were synthesized via successive atom transfer radical polymerization (ATRP). ATRP of tBA was first initiated by PEG‐Br macroinitiator using CuBr/N,N,N′,N″,N′″‐pentamethyldiethylenetriamine as catalytic system to give PEG‐b‐PtBA diblock copolymer. This copolymer was then used as macroinitiator to initiate ATRP of HEMA, which afforded the target triblock copolymer, PEG‐b‐PtBA‐b‐PHEMA. The critical micelle concentrations of obtained amphiphilic triblock copolymers were determined by fluorescence spectroscopy using N‐phenyl‐1‐naphthylamine as probe. The morphology and size of formed aggregates were investigated by transmission electron microscopy and dynamic light scattering, respectively. Finally, an acid‐sensitive PEG‐b‐PtBA‐b‐P(HEMA‐CAD) prodrug via cis‐aconityl linkage between doxorubicin and hydroxyls of triblock copolymers with a high drug loading content up to 38%, was prepared to preliminarily explore the application of triblock copolymer in drug delivery. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis of snowman‐like magnetic/nonmagnetic nanocomposite asymmetric particles via seeded emulsion polymerization initiated by γ‐ray radiation
Authors: Wang Feng‐Wei , Liu Hua‐Rong , Zhang Jin‐De , Zhou Xiang‐Tian , Zhang Xing‐Yuan
Published: August 2012

We report on the synthesis of snowman‐like magnetic/nonmagnetic nanocomposite asymmetric particles (SMNAPs) via seeded emulsion polymerization initiated by γ‐ray radiation. In situ formation of magnetite in the presence of the emulsified poly(styrene‐divinylbenzene‐acrylic acid) microspheres affords raspberry‐like magnetic nanocomposite particles, which are used as seeds for further seeded emulsion polymerization induced by γ‐ray radiation. We study the effect of the kind of surfactant, the kind and content of second monomer, and the content of swelling agent on the morphologies of the final nanocomposite particles. It is found that SMNAPs can be fabricated in high yield using 12‐acryloxy‐9‐octadecenoic acid as the surfactant and styrene as the second monomer with the addition of 2‐butanone (a swelling agent). The as‐synthesized SMNAPs may serve as magnetically controllable solid surfactants to stabilize O/W immiscible mixtures, which preferentially orientated at the interface. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Organic solvent‐free catalytic hydrogenation of diene‐based polymer nanoparticles in latex form: Part I. Preparation of nano‐substrate
Authors: Wang Hui , Pan Qinmin , Rempel Garry L.
Published: August 2012

Poly(butadiene‐co‐acrylonitrile) (NBR) nanoparticles were synthesized in a semibatch emulsion polymerization system using Gemini surfactant trimethylene‐1,3‐bis (dodecyldimethylammonium bromide), referred to as Gemini‐type surfactant (GS) 12‐3‐12, as the emulsifier. In this polymerization system, an enhanced decomposition rate of initiator ammonium persulfate was achieved even under the low temperature of 50 °C which is attributed to the acidic initiation environment provided using GS 12‐3‐12. The microstructure and copolymer composition of the polymer nanoparticles were characterized by Fourier‐transformed infrared and 1H nuclear magnetic resonance spectroscopy. The effects of the surfactant concentration on the particle size, zeta potential, polymerization conversion, copolymer composition, molecular weight, and glass transition temperature (Tg) were investigated. It was found that the particle diameter can be controlled by the surfactant concentration and monomer/water ratio and particle sizes below 20 nm can be reached. The obtained latex particles exhibit a spherical morphology. A kinetic study of the copolymerization reaction was carried out, which indicated that an azeotropic composition was produced. The synthesized fine NBR nanoparticles can be employed as the nano substrate for a subsequent hydrogenation process so as to overcome the challenge involved in the field of latex hydrogenation of polymers, which can be found in a related report: Organic Solvent‐Free Catalytic Hydrogenation of Diene‐based Polymer Nanoparticles in Latex Form: Part II. Kinetic Analysis and Mechanistic Study. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Conformationally restricted linear polyurethanes from acetalized sugar‐based monomers
Authors: Begines Belén , Zamora Francisca , Benito Elena , García‐Martín Mª de Gracia , Galbis Juan A.
Published: August 2012

Linear polyurethanes based on sugar monomers having D‐gluco, galacto, and D‐manno configurations and their secondary hydroxyl groups protected as bicyclic acetals, have been prepared by polyaddition reaction of these diol monomers to hexamethylene diisocyanate (HMDI) and 4,4′‐methylene‐bis(phenyl isocyanate) (MDI). The new polyurethanes seem to be amorphous materials, except that obtained from 2,3:4,5‐di‐O‐methylene‐galactitol and HMDI. Weight‐average molecular weights, determined by GPC, were in the range 16,000–115,200. TGA analyses indicated that the thermal stability of these bicyclic polyurethanes is comparable to those based on the isosorbide; both the onset and the maximum rate decomposition temperatures increased significantly with respect to the polyurethanes based on acyclic sugar monomers. The presence of the acetalized alditol units in the polyurethanes also increased the Tgs as compared with their acyclic analogs. Deacetalization of the polyurethanes containing di‐O‐isopropylidene‐D‐mannitol units yielded the polyhydroxylated polymers in good yields, without apparent degradation of the polymer chain. These hydroxylated polymers showed an enhanced hydrophilicity and degradability and lower Tgs and thermal stability than their parent acetalized polyurethanes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis of multiwalled carbon nanotube/fluorine‐containing poly(p‐phenylene benzoxazole) composites exhibiting greatly enhanced dielectric constants
Authors: Zhuang Qixin , Mao Xiaoyang , Xie Zhong , Liu Xiaoyun , Wang Qing , Chen Yi , Han Zhewen
Published: August 2012

A series of high‐performance polymer/carbon nanotube (CNT) composites with different nanotube contents have been prepared via condensation of N‐silylated diamino terminated precursor of the polymer with acid chloride‐functionalized CNTs and subsequent thermal cyclodehydration. The composites have been fully characterized by infrared and Raman spectroscopy, electron microscopy, and thermal analysis. Various interesting morphologic features including helical structures have been observed in the composites as a result of covalent attachment of the polymer. The composites exhibit excellent thermal stability and a significant improvement in the dielectric constant and mechanical strength with the inclusion of CNTs. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Unprecedented diverse nanostructures formed by amphiphilic graft copolymer bearing PEO side chains synthesized by ATNRC
Authors: Li Yaogong , Du Ming , Li Yongjun , Sui Long , Lu Guolin , Huang Xiaoyu
Published: August 2012

A series of well‐defined amphiphilic graft copolymers bearing hydrophilic poly(ethylene oxide) (PEO) side chains with tunable grafting densities were synthesized by atom transfer nitroxide radical coupling (ATNRC) reaction using CuBr/PMDETA as catalytic system via the grafting‐onto strategy. PEO side chains were linked to α‐C of carbonyl of polyacrylate‐based backbone, not to the ester side groups as usual, so that every repeating unit of the backbone possessed a pendant steric bulky tert‐butyl group. The critical micelle concentrations of the obtained amphiphilic graft copolymers in aqueous media determined by fluorescence probe technique using pyrene as probe increased with the raising of molecular weights. These amphiphilic graft copolymers with novel chemical structure showed unprecedented diverse nanostructures visualized by transmission electron microscopy in aqueous media and micellar morphologies varied with the changing of experiment parameters. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Oxidative polymerization of 2,6‐dimethylphenol to form poly(2,6‐dimethyl‐1,4‐phenylene oxide) in water through one water‐soluble copper(II) complex of a zwitterionic calix[4]arene
Authors: Wan Li‐Min , Li Hong‐Xi , Zhao Wei , Ding Hong‐Ye , Fang Yang‐Yang , Ni Pei‐Hong , Lang Jian‐Ping
Published: August 2012

In the presence of excess NaOH, reaction of Cu(OAc)2·H2O with equimolar ammonium calix[4]arene [H4L]I4 (1, H4L = [5,11,17,23‐tetrakis(trimethylammonium)‐25,26,27,28‐tetrahydroxycalix[4]arene]) resulted in the formation of a mononuclear cationic Cu(II) complex [Cu(II)L(H2O)]I2 (2) in 43% yield. Complex 2 was characterized by elemental analysis, infrared (IR), and single crystal X‐ray diffraction. The Cu(II) atom in 2 is coordinated by four oxygen atoms of one L4− ligand and one O atom from one water molecule, forming a square pyramidal geometry. Complex 2 exhibited high catalytic activity in the oxidative polymerization of 2,6‐dimethylphenol using O2 as oxidizing agent in water under mild conditions. The selective polymerization produced poly(2,6‐dimethyl‐1,4‐phenylene oxide) in high yields with almost no diphenoquinone. The influence of the polymerization temperature, the time interval, the molar ratio of 2,6‐dimethylphenol/2, the concentrations of sodium hydroxide, and sodium n‐dodecyl sulfate were examined. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
A novel poly(p‐phenylene) containing alternating poly(perfluorooctylethyl acrylate‐co‐methyl methacrylate) and polystyrene grafts by combination of atom transfer radical polymerization and Suzuki coupling processes
Authors: Durmaz Yasemin Yuksel , Sahkulubey Elif L. , Yagci Yusuf , Martinelli Elisa , Galli Giancarlo
Published: August 2012

A poly(p‐phenylene) (PP), carrying perfectly alternating, well‐defined poly(perfluorooctylethyl acrylate‐co‐methyl methacrylate) [P(FEA‐co‐MMA)] and polystyrene (PS) side chain grafts, was synthesized by the combination of atom transfer radical polymerization (ATRP) and Suzuki cross‐coupling processes. First, dibromobenzene and diboronic ester functional macromonomers of P(FEA‐co‐MMA) and PS, respectively, were prepared by ATRP. In the second step, PP with lateral alternating P(FEA‐co‐MMA) and PS chains was synthesized by a Suzuki coupling reaction in the presence of Pd(PPh3)4 catalyst. The wetting behavior of the polymers was studied by measurements of the static contact angle θ of thin films (200−400 nm thickness) using water and n‐hexadecane as wetting liquids. The obtained fluorinated PP showed high static contact angles with both interrogating liquids, exhibiting simultaneously hydrophobic (θw = 111°) and lipophobic (θh = 67°) properties. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Void properties in silicon heavily doped with arsenic and phosphorus
Authors: Voronkov Vladimir , Falster Robert , Porrini Maria , Duchini Januscia
Published: August 2012

Grown‐in voids in silicon are strongly affected by donor dopants. For As‐doped wafers, voids (revealed as light‐scattering surface defects observed after cleaning) show a pronounced increase in their density up to [As] = 1.7 × 1019 cm−3, but at higher [As] the void density drops sharply. A similar behaviour was found for P‐doped wafers where a sharp drop occurs at [P] > 2.9 × 1019 cm−3. Such a dependence is accounted for by an effect of minor impurity species: vacancy‐impurity complexes (trapped vacancies) and interstitial impurity atoms (trapped self‐interstitials). The total incorporated concentration of the vacancy species is first incremented due to the trapped vacancies. At higher impurity concentrations, it is reduced due to an increased contribution of negatively charged interstitial impurity species. The simulated dependence of void density and size on the impurity concentration is well consistent with the experimental data.
Copper‐alloyed ZnS as a p‐type transparent conducting material
Authors: Diamond Anthony M. , Corbellini Luca , Balasubramaniam K. R. , Chen Shiyou , Wang Shuzhi , Matthews Tyler S. , Wang Lin‐Wang , Ramesh Ramamoorthy , Ager Joel W.
Published: August 2012

Copper alloyed ZnS was investigated as a p‐type, transparent conducting material composed of earth‐abundant elements. Thin films of Cu‐alloyed ZnS were synthesized using pulsed laser deposition with Cu contents in the range of x = 0.06–0.27 (Cu content x is reported as the fraction of cation present). Thermopower and Hall effect measurements show that the films are p‐type. We find that transparency and conductivity are comparable to some of the best reported p‐type materials with our best films exhibiting conductivities of 54 S cm−1 and optical transmission of 65% at 550. The hole conduction mechanism is discussed in terms of possible Cu acceptor doping of the ZnS and hole conductivity in a minority Cu2S phase. Transparent rectifying p‐CuZnS/n‐ZnO diodes were fabricated.

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Photo demonstrating the high transparency of a rectifying heterojunction diode made with p‐type Cu‐alloyed ZnS and n‐type ZnO.
Role of potential fluctuations in phase‐change GST memory devices
Authors: Agarwal Satish C.
Published: August 2012

The long range potential fluctuations (LRPFs) arising from the defects and heterogeneities in disordered semiconductors are important for understanding their atomic and electronic properties. Here, they are measured in GeXSbYTe1−X−Y (GST) chalcogenide glasses used in rewritable phase change memory (PCM) devices. It is found that the most commonly used composition Ge2Sb2Te5 has the smallest LRPF amongst its nearby compositions. This finding may be useful in the search for better PCM materials.
Stability of 71° stripe domains in epitaxial BiFeO3 films upon repeated electrical switching
Authors: Johann Florian , Morelli Alessio , Vrejoiu Ionela
Published: August 2012

The 71° stripe domain patterns of epitaxial BiFeO3 thin films are frequently being explored to achieve new functional properties, dissimilar from the BiFeO3 bulk properties. We show that in‐plane switching and out‐of‐plane switching of these domains behave very differently. In the in‐plane configuration the domains are very stable, whereas in the out‐of‐plane configuration the domains change their size and patterns, depending on the applied switching voltage frequency.

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Reducing Effect of a Combination of Phaseolus vulgaris and Cynara scolymus Extracts on Operant Self‐Administration of a Chocolate‐Flavoured Beverage in Rats
Authors: Zaru Alessandro , Maccioni Paola , Riva Antonella , Morazzoni Paolo , Bombardelli Ezio , Gessa Gian Luigi , Carai Mauro A. M. , Colombo Giancarlo
Published: August 2012

Treatment with a rational combination of standardized extracts of Phaseolus vulgaris and Cynara scolymus reduced food intake and glycemia in rats. The present study was designed to assess the effect of this extract combination and of each single extract in an experimental model of food craving, made up of rats displaying exaggerated seeking and taking behaviors for a chocolate‐flavoured beverage. After training to lever‐respond for the chocolate‐flavoured beverage, rats were treated with vehicle, Phaseolus vulgaris extract alone (200 mg/kg), Cynara scolymus extract alone (400 mg/kg), or combination of Phaseolus vulgaris (200 mg/kg) and Cynara scolymus (400 mg/kg) extracts. The Phaseolus vulgaris extract and the extract combination exerted similar and substantial decrements in the number of lever‐responses and amount of self‐administered chocolate‐flavoured beverage; conversely, the Cynara scolymus extract was totally ineffective. These results suggest that (i) the capacity of the extract combination to reduce the self‐administration of the chocolate‐flavoured beverage entirely relied on the Phaseolus vulgaris extract, (ii) Phaseolus vulgaris extract may interfere with the mechanisms regulating food‐related addictive‐like behaviors, and (iii) combinations of Phaseolus vulgaris and Cynara scolymus extracts may possess a broad spectrum of activities, from treatment of metabolic syndrome to overweight, obesity, and possibly food‐related addictive disorders. Copyright © 2012 John Wiley & Sons, Ltd.
Nonlinear model predictive control of wind turbines using LIDAR
Authors: Schlipf David , Schlipf Dominik Johannes , Kühn Martin
Published: August 2012

LIDAR systems are able to provide preview information of wind disturbances at various distances in front of wind turbines. This technology paves the way for new control concepts in wind energy such as feedforward control and model predictive control. This paper compares a nonlinear model predictive controller with a baseline controller, showing the advantages of using the wind predictions in the optimization problem to reduce wind turbine extreme and fatigue loads on tower and blades as well as to limit the pitch rates. The wind information is obtained by a detailed simulation of a LIDAR system. The controller design is evaluated and tested in a simulation environment with coherent gusts and a set of turbulent wind fields using a detailed aeroelastic model of the wind turbine over the full operation region. Results show promising load reduction up to 50% for extreme gusts and 30% for lifetime fatigue loads without negative impact on overall energy production. This controller can be considered as an upper bound for other LIDAR assisted controllers that are more suited for real time applications. Copyright © 2012 John Wiley & Sons, Ltd.
A multivariate approach to estimate design loads for offshore wind turbines
Authors: Guanche Yanira , Guanche Raúl , Camus Paula , Mendez Fernando J. , Medina Raúl
Published: August 2012

The design of offshore wind farms is a complex process that requires a detailed study of the oceanographic, meteorological and geotechnical conditions at the site. The structure and all structural members shall be designed in a way that they can be resistant against different kinks of loads: permanent, variable, environmental, accidental and deformations. This paper is focused on those called environmental loads. The main environmental conditions that may contribute to structural damage, operational disturbances or other failures are wind, waves, currents and sea ice. Thus, the combination of the different parameters may produce many different critical situations for the integrity of the structure, requiring the calculation of long time series corresponding to long‐term historical data situations. The most accurate techniques available at the moment to estimate loads acting upon a structure are numerical and physical models; however, they are very time consuming, and the calculation of long time series of data is unfeasible. Therefore, a new hybrid methodology to select waves–wind–current representative conditions that allow the interpolation of long time series of forces on a wind turbine is proposed. The methodology consists of a selection of a subset of representative cases of wave–wind–current climate at the structure's location by using a maximum dissimilarity algorithm, then estimating loads acting upon the structure for the sea–wind states selected and the reconstruction of loads corresponding to historical data using an interpolation technique based on radial basis function. To validate the proposed methodology and because of there is no availability of long time records of loads on wind turbines, the well‐known IEC 61400–3 has been applied to estimate the loads for the complete reanalysis time series of waves, winds and currents. The validation of the results confirms the ability of the methodology developed to reconstruct time series of forces on the structure on the basis of the previously selected cases. This methodology permits application of numerical and physical models to offshore wind farm design, considerably reducing the number of tests or simulations. Copyright © 2012 John Wiley & Sons, Ltd.
Optimization‐based study of bend–twist coupled rotor blades for passive and integrated passive/active load alleviation
Authors: Bottasso C.L. , Campagnolo F. , Croce A. , Tibaldi C.
Published: August 2012

This work is concerned with the design of wind turbine blades with bend‐twist‐to‐feather coupling that self‐react to wind fluctuations by reducing the angle of attack, thereby inducing a load mitigation effect. This behavior is obtained here by exploiting the orthotropic properties of composite materials by rotating the fibers away from the pitch axis.

The first part of this study investigates the possible configurations for achieving bend‐twist coupling. At first, fully coupled blades are designed by rotating the fibers for the whole blade span, and a best compromise solution is found to limit weight increase by rotations both in the spar caps and in the skin. Next, partially coupled blades are designed where fibers are rotated only on the outboard part of the blade, this way achieving good load mitigation capabilities together with weight savings. All blades are designed with a multilevel constrained optimization procedure, on the basis of combined cross‐sectional, multibody aero‐servo‐elastic and three‐dimensional finite element models.

Finally, the best configuration of the passive coupled blade is combined with an active individual pitch controller. The synergistic use of passive and active load mitigation technologies is shown to allow for significant load reductions while limiting the increase in actuator duty cycle, thanks to the opposite effects on this performance metric of the passive and active control solutions. Copyright © 2012 John Wiley & Sons, Ltd.
Integrated bioprocess for the stereospecific production of linalool oxides from linalool with Corynespora cassiicola DSM 62475
Authors: Bormann Sebastian , Etschmann Maria M W , Mirata Marco-Antonio , Schrader Jens
Published: August 2012

Linalool oxides are of interest to the flavour industry because of their lavender notes. Corynespora cassiicola DSM 62475 has been identified recently as a production organism because of high stereoselectivity and promising productivities [Mirata et al. (2008) J Agric Food Chem 56(9):3287–3296]. In this work, the stereochemistry of this biotransformation was further investigated. Predominantly (2R)-configured linalool oxide enantiomers were produced from (R)-(−)-linalool. Comparative investigations with racemic linalool suggest that predominantly (2S)-configured derivatives can be expected by using (S)-(+)-configured substrate. Substrate and product inhibited growth even at low concentrations (200 mg l−1). To avoid toxic effects and supply sufficient substrates, a substrate feeding product removal (SFPR) system based on hydrophobic adsorbers was established. Applying SFPR, productivity on the shake flask scale was increased from 80 to 490 mg l−1 day−1. Process optimisation increased productivity to 920 mg l−1 day−1 in a bioreactor with an overall product concentration of 4.600 mg l−1 linalool oxides.
Who Counsels Parents of Newborns Who Are Carriers of Sickle Cell Anemia or Cystic Fibrosis?
Authors: Moseley Kathryn L. , Nasr Samya Z. , Schuette Jane L. , Campbell Andrew D.
Published: August 2012

Our objective was to describe: 1) physicians’ knowledge of whether genetic counseling is provided to parents of newborns with sickle cell trait (SCT) or who are cystic fibrosis carriers (CFC), and 2) the prevalence of genetic counseling provided by primary care physicians. We conducted a cross‐sectional descriptive survey of 600 randomly‐sampled Michigan‐based pediatricians and family physicians, assessing physician knowledge of where and whether genetic counseling is received by parents whose newborns are carriers. Chi‐squared testing determined associations between genetic counseling location and physician demographic characteristics. Our response rate was 62 %: 298 (84 %) provided infant well care (183 pediatricians, 115 family physicians). Most respondents were non‐Hispanic White (65 %). Virtually all physicians believed parents whose newborns are carriers of either SCT or CFC should receive some genetic counseling (from the physician and/or another source), yet 20 % reported that parents of newborns with SCT did not receive counseling. Parents of infants with CFC received more counseling overall (92 % vs. 80 %; p < 0.01) and were counseled more frequently by genetic counselors or specialty centers than parents of newborns with SCT (85 % vs. 60 %; p < 0.01). Although physicians agreed that parents whose newborns are carriers should receive genetic counseling, fewer parents of newborns with SCT than with CFC received counseling from any source. This finding strongly suggests the need for further education and investigation of this apparent health disparity.
Trans Fatty Acid Intakes and Food Sources in the U.S. Population: NHANES 1999–2002
Authors: Kris‐Etherton Penny M. , Lefevre Michael , Mensink Ronald P. , Petersen Barbara , Fleming Jennifer , Flickinger Brent D.
Published: August 2012

Because of efforts to decrease trans fatty acids (TFA) in the food supply, intake should be assessed in the population to establish a baseline TFA intake. The 1999–2002 National Health and Nutrition Examination Survey (NHANES) was used to identify a benchmark for TFA intake. TFA was estimated by mean, median, and quintile of intake, TFA intake data were weighted using the NHANES 4‐year sample weights. The main outcome measures included TFA intake in grams per day and percentage of energy in the top 25 food sources of TFA. Data are reported for 16,669 individuals ≥3 years of age. Median TFA intake was 2.3 % of calories (5 g/day) with 0.9–4.5 % of energy (1.5–13.1 g/day) over different quintiles of intake. Mean TFA intake was 2.5 % of energy (6.1 g/day). The range of TFA intake in the fifth quintile was very large, i.e., 3.5–12.5 % of energy or 8.8–92.4 g/day. Increasing quintiles of TFA intake were associated with increases in total fat (26.7–37.6 % of energy), saturated fat (7.6–10.5 % of energy), and calories (for those >20 years of age: 2,416–2,583 for men and 1,679–1,886 for women). Major food sources of dietary TFA were cakes, cookies, pies, and pastries. Based on current dietary guidance to consume as little industrial TFA as possible, much progress is needed to attain this goal, including food industry efforts to remove TFA from the food supply and educating the public about making healthy food choices.