bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temporal proteomic analysis of IGF‐1R signalling in MCF‐7 breast adenocarcinoma cells
Authors: Murphy J. Patrick , Pinto Devanand M. 
Published: March 2010

AbstractDysregulation of the insulin‐like growth factor 1 receptor signalling network is implicated in tumour growth and resistance to chemotherapy. We explored proteomic changes resulting from insulin‐like growth factor 1 stimulation of MCF‐7 adenocarcinoma cells as a function of time. Quantitative analysis using iTRAQ™ reagents and 2‐D LC‐MS/MS analysis of three biological replicates resulted in the identification of 899 proteins (p≤0.05) with an estimated mean false‐positive rate of 2.6%. Quantitative protein expression was obtained from 681 proteins. Further analysis by supervised k‐means clustering identified five temporal clusters, which were submitted to the FuncAssociate server to assign overrepresented gene ontology terms. Proteins associated with vesicle transport were significantly overrepresented. We further analyzed our data set for proteins showing temporal significance using the software, extraction and analysis of differential gene expression, resulting in 20 significantly and temporally changing proteins (p≤0.1). These significant proteins play roles in, among others, altered glucose metabolism (lactate dehydrogenase A and pyruvate kinase M1/M2) and cellular stress (nascent polypeptide‐associated complex subunit α and heat shock (HSC70) proteins). We used multiple reaction monitoring to validate these interesting proteins and have revealed several differences in relative peptide expression corresponding to protein isoforms and variants.
Pendant structure governed anion sensing property for sulfonamide‐functionalized poly(phenylacetylene)s bearing various α‐amino acids
Authors: Kakuchi Ryohei , Shimada Ryotaro , Tago Yasuyuki , Sakai Ryosuke , Satoh Toshifumi , Kakuchi Toyoji 
Published: March 2010

AbstractThe colorimetric detection of anionic species has been studied for α‐amino acid‐conjugated poly(phenylacetylene)s, which were prepared by the polymerization of the ethyl esters of N‐(4‐ethynylphenylsulfonyl)‐L‐alanine, L‐isoleucine, L‐valine, L‐phenylalanine, L‐aspartic acid, and L‐glutamic acid using Rh+(2,5‐norbornadiene)[(η6‐C6H5)B−(C6H5)3] as the catalyst in CHCl3. The one‐handed helical conformations of all the sulfonamide‐functionalized polymers were characterized by Cotton effects in the circular dichroism spectra. The addition of anions with a relatively high basicity, such as tetra‐n‐butylammonium acetate and fluoride, induced drastic changes in both the optical and chiroptical properties. On the other hand, anions with a relatively low basicity, such as tetra‐n‐butylammonium nitrate, azide, and bromide, had essentially no effects on the helical conformation of all the sulfonamide‐functionalized polymers. The anion signaling property of the sulfonamide‐functionalized polymers possessing α‐amino acid moieties was significantly affected by the installed residual amino acid structures. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1683–1689, 2010
End‐functionalization of syndiotactic polystyrene by vinylsilane inducing selective chain transfer reactions
Authors: Hsiao Ting‐Jui , Tsai Jing‐Cherng 
Published: March 2010

AbstractStructurally well‐defined end‐functionalized syndiotactic polystyrene (sPS) can be prepared by conducting a simultaneous selective chain transfer reaction during the syndiospecific polymerization of styrene in the presence of vinylsilanes. The production of vinylsilane end‐capped sPS involves a unique selective chain transfer pathway via the incorporation of a terminal vinylsilane unit at the polymer chain end by 2,1‐insertion. This unusual insertion pattern situates the bulky silyl functional group at a closer β‐position from the active catalyst center, thus deactivating the propagating chain by a steric jam between the vinylsilane end group and the active catalyst. Subsequently, chain releasing by hydrogen addition (in the presence of H2) or by β‐elimination (in the absence of H2) can take place, which leads to the production of end‐functionalized sPS with precise controls of stereoregularity and of the location of functionality. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1690–1698, 2010
Limitations of radical thiol‐ene reactions for polymer–polymer conjugation
Authors: Koo Sandy P. S. , Stamenović Milan M. , Prasath R. Arun , Inglis Andrew J. , Du Prez Filip E. , Barner‐Kowollik Christopher , Van Camp Wim , Junker Tanja 
Published: March 2010

AbstractIn this work, we report our findings on the use of radical thiol‐ene chemistry for polymer–polymer conjugation. The manuscript combines the results from the Preparative Macromolecular Chemistry group from the Karlsruhe Institute of Technology (KIT) and the Polymer Chemistry Research group from Ghent University (UGent), which allowed for an investigation over a very broad range of reaction conditions. In particular, thermal and UV initiation methods for the radical thiol‐ene process were compared. In the KIT group, the process was studied as a tool for the synthesis of star polymers by coupling multifunctional thiol core molecules with poly(n‐butyl acrylate) macromonomers (MM), employing thermally decomposing initiators. The product purity and thus reaction efficiency was assessed via electrospray ionization mass spectrometry. Although the reactions with 10 or 5 equivalents of thiol with respect to macromonomer were successful, the coupling reaction with a one‐to‐one ratio of MM to thiol yielded only a fraction of the targeted product, besides a number of side products. A systematic parameter study such as a variation of the concentration and nature of the initiator and the influence of thiol‐to‐ene ratio was carried out. Further experiments with poly(styrene) and poly(isobornyl acrylate) containing a vinylic end group confirmed that thermal thiol‐ene conjugation is far from quantitative in terms of achieving macromolecular star formation. In parallel, the UGent group has been focusing on photo‐initiated thiol‐ene chemistry for the synthesis of functional polymers on one hand and block copolymers consisting of poly(styrene) (PS) and poly(vinyl acetate) (PVAc) on the other hand. Various functionalization reactions showed an overall efficient thiol‐ene process for conjugation reactions of polymers with low molecular weight compounds (∼90% coupling yield). However, while SEC and FT‐IR analysis of the conjugated PS‐PVAc products indicated qualitative evidence for a successful polymer–polymer conjugation, 1H NMR and elemental analysis revealed a low conjugation efficiency of about 23% for a thiol‐to‐ene ratio equal to one. Blank reactions using typical thiol‐ene conditions indicated that bimolecular termination reactions occur as competitive side reactions explaining why a molecular weight increase is observed even though the thiol‐ene reaction was not successful. The extensive study of both research groups indicates that radical thiol‐ene chemistry should not be proposed as a straightforward conjugation tool for polymer–polymer conjugation reactions. Head‐to‐head coupling is a major reaction pathway, which interrupts the propagation cycle of the thiol‐ene process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1699–1713, 2010
Synthesis of comb polymers via grafting‐onto macromolecules bearing pendant diene groups via the hetero‐Diels‐Alder‐RAFT click concept
Authors: Bousquet Antoine , Barner‐Kowollik Christopher , Stenzel Martina H. 
Published: March 2010

AbstractComb polymers were synthesized by the “grafting‐onto” method via a combination of Reversible Addition‐Fragmentation Chain Transfer (RAFT) polymerization and the hetero‐Diels‐Alder (HDA) cycloaddition. The HDA reactive monomer trans, trans‐hexa‐2,4‐dienylacrylate (ttHA) was copolymerized with styrene via the RAFT process. Crosslinking was minimized by decreasing the monomer concentration—whilst keeping monomer to polymer conversions low—resulting in reactive backbones with on average one reactive pendant diene groups for 10 styrene units. The HDA cycloaddition was performed between the diene functions of the copolymer and a poly(n‐butyl acrylate) (PnBA) prepared via RAFT polymerization with pyridin‐2‐yldithioformate, which can act as a dienophile. The coupling reactions were performed within 24 h at 50 °C and the grafting yield varies from 75% to 100%, depending on the number average molecular weight of the PnBA (3500 g mol−1 < Mn < 13,000 g mol−1) grafted chain and the reaction stoichiometry. The molecular weights of the grafted block copolymers range from 19,000 g mol−1 to 58,000 g mol−1 with polydispersities close to 1.25. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1773–1781, 2010
Synthesis and properties of conjugated polymers containing 3,9‐carbazolylene and silylenevinylene moieties in the main chain
Authors: Sasano Tatsuya , Sogawa Hiromitsu , Tamura Kosaku , Shiotsuki Masashi , Masuda Toshio , Sanda Fumio 
Published: March 2010

AbstractNovel conjugated polymers containing 3,9‐carbazolylene and silylenevinylene moieties were synthesized by the hydrosilylation polymerization of 1,4‐bis(3‐ethynyl‐9‐carbazolyl)benzene (1) with various bis(hydrosilane)s or dihydrosilanes using a rhodium catalyst. Polymers with weight‐average molecular weights ranging from 5400 to 20,000 were obtained in 55–97% yields by the polyaddition with a rhodium catalyst in toluene at 25 °C for 24 h. All the polymers were soluble in CHCl3 and THF, and had predominantly trans‐structures. The polymers exhibited λmax at a longer wavelength region than 1, and emitted fluorescence in 14–50% quantumn yields. The polymers were oxidized and reduced in the region of 0.4–1.6 V, and thermally stable up to 200 °C under air. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1815–1821, 2010
Poly(4,8‐bis(2‐ethylhexyloxy)benzo[1,2‐b:4,5‐b′]dithiophene vinylene): Synthesis, optical and photovoltaic properties
Authors: He Youjun , Zhou Yi , Zhao Guangjin , Min Jie , Guo Xia , Zhang Bo , Zhang Maojie , Zhang Jing , Li Yongfang , Zhang Fengling , Inganäs Olle 
Published: March 2010

AbstractA new benzodithiophene (BDT)‐based polymer, poly(4,8‐bis(2‐ethylhexyloxy)benzo[1,2‐b:4,5‐b′]dithiophene vinylene) (PBDTV), was synthesized by Pd‐catalyzed Stille‐coupling method. The polymer is soluble in common organic solvents and possesses high thermal stability. PBDTV film shows a broad absorption band covering from 350 nm to 618 nm, strong photoluminescence peaked at 545 nm and high hole mobility of 4.84 × 10−3 cm2/Vs. Photovoltaic properties of PBDTV were studied by fabricating the polymer solar cells based on PBDTV as donor and PC70BM as acceptor. With the weight ratio of PBDTV: PC70BM of 1:4 and the active layer thickness of 65 nm, the power conversion efficiency of the device reached 2.63% with Voc = 0.71 V, Isc = 6.46 mA/cm2, and FF = 0.57 under the illumination of AM1.5, 100 mW/cm2. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1822–1829, 2010
Predicting explosibility properties of chemicals from quantitative structure‐property relationships
Authors: Fayet G. , Rotureau P. , Joubert L. , Adamo C. 
Published: March 2010

AbstractQuantitative Structure‐Property Relationship (QSPR) type methods have been up to now mainly devoted to biological, toxicological applications but their use to predict physico‐chemical properties is a growing interest. In this context, an original approach associating QSPR methods and quantum chemical calculations for the prediction of chemicals explosibility properties is presented here.Indeed, the new European regulation of chemicals named REACH implies the new assessment of a tremendous number of substances for their hazardous properties. But, the complete characterization of toxicological, ecotoxicological, and physico‐chemical hazards at experimental level is incompatible with the imposed calendar of REACH. Hence, there is a real need in evaluating capabilities of alternative methods for assessing hazardous properties as a screening process.This contribution focuses on models that have been established to predict accurately the thermal stability and electric spark sensitivity of a series of potentially explosive nitroaromatic molecules. Descriptors related to their molecular structure (topological, geometrical, electronic, quantum chemical), partially obtained from density functional theory (DFT) calculations, were computed and statistical analyses (multilinear regressions) were performed to link the adequate molecular descriptors with the experimental properties. These first results coupling theoretical calculations and QSPR methods open new perspectives for the prediction of other physico‐chemical properties. © 2010 American Institute of Chemical Engineers Process Saf Prog 2010
Microstructure of N‐face InN grown on Si (111) by plasma‐assisted MBE using a thin GaN–AlN buffer layer
Authors: Dimitrakopulos G. P. , Kehagias Th. , Ajagunna A. , Kioseoglou J. , Kerasiotis I. , Nouet G. , Vajpeyi A. P. , Komninou Ph. , Karakostas Th. 
Published: March 2010

AbstractThe structural properties of 2 µm thick N‐face InN film, grown on Si (111) by plasma source molecular beam epitaxy after the initial deposition of 20 nm AlN and 40 nm GaN, were examined by transmission electron microscopy. The lattice mismatched GaN/AlN and InN/GaN interfaces limited the propagation of threading dislocations (TDs). Dislocation annihilation interactions occurred in the first ∼200 nm of the InN film and reduced the TD density. However, the density of screw and mixed type TDs was four times higher than edge type ones. This was attributed to the observed GaN/InN interfacial roughness, which was introduced by terminating TDs from the GaN/AlN buffer layer. Strain measurements showed that the InN film, as well as both buffer layers, was relaxed.
New twists in LEDs and HFETs based on nitride semiconductors
Authors: Leach J. H. , Ni X. , Lee J. , Özgür Ü. , Matulionis A. , Morkoç H. 
Published: March 2010

AbstractDespite notable progress in light‐emitting and charge transport devices based on GaN heterostructures containing In, there is still controversy as to the light emission characteristics at high injection levels in InGaN‐based light‐emitting diodes (LEDs) and hot‐carrier scattering in GaN‐based field effect transistors (FETs) with AlGaN or AlInN barriers. For LEDs to be inserted into conventional lighting systems, reasonably high efficiencies would have to be retained at high injection levels to meet intensity requirements which is not yet borne out by many experiments but might be mitigated by use of nonpolar m‐plane varieties according to the most recent data. The efficiency degradation at high injection levels, beyond that which is expected due to heating and current crowding, has been attributed by what is shaping up to be two camps to mainly Auger recombination and carrier spillover. The latter has been attributed to or helped by polarization‐induced fields which is contrary to again recent experiments on LEDs. In terms of the FETs the conventional wisdom of increased carrier concentrations leading to better devices does not seem to hold beyond a certain point. This is due to strong electron LO phonon coupling in this highly ionic material and the resultant hot phonon population. Hot phonon lifetime decreases with increasing carrier concentration up to a point owing to plasmon–phonon interaction. But beyond the concentration at which the plasma frequency and phonon frequency match, the phonon lifetime begins to increase again. Increased phonon lifetimes lead to reduced carrier velocity and inefficient heat transfer, and thus performance degradation ensues. Another intriguing feature is that the aforementioned phenomenon is electric field dependent at least because increased field in FETs means widening of the channel and thus for the same volume density the resonance occurs at higher sheet densities. In this paper the details of carrier recombination in the context of InGaN LEDs both on polar c‐plane and nonpolar m‐plane GaN at high injection levels, and hot‐carrier‐scattering‐related physics in the context of HFETs based on the GaN material family containing In will be elucidated.
23Na and 87Rb relaxation study of the structural phase transitions in the Tutton salts Na2Zn(SO4)2·6H2O and Rb2Zn(SO4)2·6H2O single crystals
Authors: Lim Ae Ran , Lee Ju Ha 
Published: March 2010

AbstractThe NMR spectrum, spin–lattice relaxation times, T1, and the spin–spin relaxation times, T2, for the 23Na and 87Rb nuclei in Tutton salts Na2Zn(SO4)2·6H2O and Rb2Zn(SO4)2·6H2O single crystals were determined by using an FT NMR spectrometer. The NMR spectrum and relaxation times for the 23Na and 87Rb nuclei in two crystals undergo significant changes near TC. These changes close to TC were the only detectable result of the structural transformation; the change is due to the fact that the electric field gradient value becomes 0. Especially, T1 and T2 for 87Rb in the Rb2Zn(SO4)2·6H2O crystals at high temperature have similar values on the order of milliseconds, which is indicative of a liquid‐like system. The motion giving rise to this liquid‐like behavior is probably related to superionic motion at high temperature.
The influence of dipolar interaction on magnetic properties in nanomagnets with different shapes
Authors: Li Ying , Wang TianXing , Li YangXian 
Published: March 2010

AbstractWith the Monte Carlo method, we investigate the magnetic properties of four nanomagnets of different shapes, i.e., the circular‐shaped, the square‐shaped, the elliptical, and the ring‐shaped nanomagnets. A systematic study of the effects of the dipolar interaction on the magnetic configurations is performed in these nanomagnets, and further the coercive field and the remanence as a function of dipolar interaction are analyzed. The results show that the magnetic configuration and thus the magnetization reversal process of nanomagnets are dependent strongly on the strength of dipolar interactions. For the case of small dipolar interaction, the magnetization reversal process is mainly dominated by spin rotation, while the reversal transforms to the vortex nucleation and propagation formations with increasing dipolar interaction. Moreover, if the dipolar interaction is neglected in the calculation of the total energy, no clear difference is found among hysteresis loops of four nanomagnets with same areas, but the inclusion of dipolar interaction can lead to different hysteresis loops for nanomagnets with same areas but different shapes. This indicates that the dipolar interaction is important for accounting for the shape effect of the magnetic properties in nanomagnets.
Feasibility of capillary liquid chromatography/microchip atmospheric pressure photoionization mass spectrometry in analyzing anabolic steroids in urine samples
Authors: Ahonen Linda L. , Haapala Markus , Saarela Ville , Franssila Sami , Kotiaho Tapio , Kostiainen Risto 
Published: March 2010

AbstractWe examined the feasibility of capillary liquid chromatography/microchip atmospheric pressure photoionization tandem mass spectrometry (capLC/µAPPI‐MS/MS) for the analysis of anabolic steroids in human urine. The urine samples were pretreated by enzymatic hydrolysis (with β‐glucuronidase from Helix pomatia), and the compounds were liquid‐liquid extracted with diethyl ether. After separation the compounds were vaporized by microchip APPI, photoionized by a 10 eV krypton discharge lamp, and detected by selected reaction monitoring. The capLC/µAPPI‐MS/MS method showed good sensitivity with detection limits at the level of 1.0 ng mL−1, good linearity with correlation coefficients between 0.9954 and 0.9990, and good repeatability with relative standard deviations below 10%. These results demonstrate that microchip APPI combined with capLC/MS/MS provides a new potential method for analyzing non‐polar and neutral compounds in biological samples. Copyright © 2010 John Wiley & Sons, Ltd.
Structural discrimination of isomeric tetrahydrofuran lignan glucosides by tandem mass spectrometry
Authors: Ricci Andreina , Fiorentino Antonio , Piccolella Simona , D'Abrosca Brigida , Pacifico Severina , Monaco Pietro 
Published: March 2010

AbstractDue to the possible role in human health, the number of analytical studies on lignans aimed at their quali‐ and quantitative analysis in plant extracts, biological fluids and foods is continuously increasing. However, helpful systematic mass spectrometric investigations on these compounds are few and rather limited to specific lignan sub‐classes. To increase the comprehension of the previously outlined picture of the gas‐phase properties of furofuran lignans, we extended the study to tetrahydrofuran lignans and here we reported the collision‐activated dissociation (CAD) fragmentation patterns of the alkali metal cation adducts, [M+Alk]+, and [M–H]− ions of three isomeric tetrahydrofuran lignans, (+)‐8′‐hydroxylariciresinol 4′‐O‐β‐D‐glucopyranoside (1), (+)‐7′‐hydroxylariciresinol 7′‐O‐β‐D‐glucopyranoside (2) and 4‐O‐β‐D‐glucopyranosyloxy‐3,3′‐dimethoxy‐7,9′‐epoxylignan‐5′,8′,9‐triol (3) investigated by electrospray ionization triple quadrupole mass spectrometry (ESI‐TQMS). Hydrogen/deuterium (H/D) solution exchange experiments, allowing the selective H/D exchange of all the acidic hydrogen atoms, proved to be a very effective tool to obtain information on the nature of fragments generated during TQ/CAD processes. The [M+Na]+ CAD mass spectra of the three isomeric tetrahydrofurans revealed four different pathways involving the loss of the glucose moiety, which allowed the assignment of the glycosylation site. In the negative ion mode, the main fragmentation channel of the [M–H]− ions of O‐glucosylated lignans at the phenolic oxygen atoms is represented by the loss of 162 Da. When the sugar is bound to a benzylic OH group the loss of the sugar as a 180 Da unit occurs eventually following the loss of a water molecule involving both the C(9)H2OH chain and the sugar. Copyright © 2010 John Wiley & Sons, Ltd.
Determination of the banned growth promoter moenomycin A in feed stuffs by liquid chromatography coupled to electrospray ion trap mass spectrometry
Authors: Gallo Pasquale , Fabbrocino Serena , Serpe Luigi , Fiori Maurizio , Civitareale Cinzia , Stacchini Paolo 
Published: March 2010

AbstractFlavomycin complex is an antibiotic banned in the European Union as an additive in feed stuffs. As a consequence, the monitoring programmes for official control within the Community require analysis of feeds for possible illegal use of flavomycin. A method for unambiguous identification and quantification of moenomycin A, the main pharmacologically active component of flamomycin complex, in several feeds by liquid chromatography coupled to electrospray ion trap mass spectrometry (LC/ESI‐MS/MS) is herein described for the first time. The method was developed to be used as a confirmative analytical tool for the network of Italian official control laboratories; both the singly and doubly charged molecular ions were observed as precursor ions, from which four product ions were selected for both quantitative analysis and unambiguous identification of moenomycin A. The method was in‐house validated for feeds in the concentration range 0.50–30.0 µg/g, according to the Regulation 882/2004/EC requirements. Mean recoveries ranging between 83.9–94.2% and relative standard deviations <23% account for method trueness and repeatability, respectively. Moreover, other analytical performance parameters, i.e. method specificity, ruggedness, the linearity of detector response, the limit of quantification (LOQ), the limit of detection (LOD), and measurement uncertainty were evaluated and reported. The ion trap LC/ESI‐MS/MS method is highly selective and reliable; high drug recovery, good reproducibility and an LOQ down to 0.10 µg/g guarantee its applicability for confirmatory purposes in the official control activity in Italy. Copyright © 2010 John Wiley & Sons, Ltd.