bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the improved sensitivity of spectral library searching over sequence database searching in proteomics data analysis
Authors: Zhang Xin , Li Yunzi , Shao Wenguang , Lam Henry
Published: January 2011

Spectral library searching has been recently proposed as an alternative to sequence database searching for peptide identification from MS/MS. We performed a systematic comparison between spectral library searching and sequence database searching using a wide variety of data to better demonstrate, and understand, the superior sensitivity of the former observed in preliminary studies. By decoupling the effect of search space, we demonstrated that the success of spectral library searching is primarily attributable to the use of real library spectra for matching, without which the sensitivity advantage largely disappears. We further determined the extent to which the use of real peak intensities and non‐canonical fragments, both under‐utilized information in sequence database searching, contributes to the sensitivity advantage. Lastly, we showed that spectral library searching is disproportionately more successful in identifying low‐quality spectra, and complex spectra of higher‐ charged precursors, both important frontiers in peptide sequencing. Our results answered important outstanding questions about this promising yet unproven method using well‐controlled computational experiments and sound statistical approaches.
GPDE: A biological proteomic database for biomarker discovery and evaluation
Authors: Griss Johannes , Haudek‐Prinz Verena , Gerner Christopher
Published: January 2011

Clinical proteomics faces extremely complex and variable data. Here, we present an updated version of the Griss Proteomics Database Engine (GPDE): A free biological proteomic database specifically designed for clinical proteomics and biomarker discovery (http://gpde.sourceforge.net). It combines experiments based on investigated cell types thereby supporting customizable biological meta‐analyses. Through the new features described here, the GPDE now became a powerful yet easy‐to‐use tool to support the fast identification and reliable evaluation of biomarker candidates.
Development of oleic acid‐functionalized magnetite nanoparticles as hydrophobic probes for concentrating peptides with MALDI‐TOF‐MS analysis
Authors: Chen Hemei , Liu Shasha , Li Yan , Deng Chunhui , Zhang Xiangmin , Yang Pengyuan
Published: January 2011

The oleic acid‐functionalized magnetite nanoparticles (OA‐Fe3O4) with mean diameter of about 15 nm were synthesized through a low‐cost, one‐pot method and were designed as hydrophobic probes to realize the convenient, efficient and fast concentration of low‐concentration peptides followed by MALDI‐TOF‐MS analysis. The capability of OA‐Fe3O4 nanoparticles in concentration of low‐abundance peptides from simple and complex solutions were evaluated by comparing them with a sort of C8‐modified magnetic microspheres. Samples of standard peptide solution, protein digest solution and human serum were introduced in the evaluating process, and the OA‐Fe3O4 nanoparticles exhibited good surface affinity toward low‐concentration peptides
SearchGUI: An open‐source graphical user interface for simultaneous OMSSA and X!Tandem searches
Authors: Vaudel Marc , Barsnes Harald , Berven Frode S. , Sickmann Albert , Martens Lennart
Published: January 2011

The identification of proteins by mass spectrometry is a standard technique in the field of proteomics, relying on search engines to perform the identifications of the acquired spectra. Here, we present a user‐friendly, lightweight and open‐source graphical user interface called SearchGUI (http://searchgui.googlecode.com), for configuring and running the freely available OMSSA (open mass spectrometry search algorithm) and X!Tandem search engines simultaneously. Freely available under the permissible Apache2 license, SearchGUI is supported on Windows, Linux and OSX.
A global analysis of peptide fragmentation variability
Authors: Barsnes Harald , Eidhammer Ingvar , Martens Lennart
Published: January 2011

Understanding the fragmentation process in MS/MS experiments is vital when trying to validate the results of such experiments, and one way of improving our understanding is to analyze existing data. We here present our findings from an analysis of a large and diverse data set of MS/MS‐based peptide identifications, in which each peptide has been identified from multiple spectra, recorded on two commonly used types of electrospray instruments. By analyzing these data we were able to study fragmentation variability on three levels: (i) variation in detection rates and intensities for fragment ions from the same peptide sequence measured multiple times on a single instrument; (ii) consistency of rank‐based fragmentation patterns; and (iii) a set of general observations on fragment ion occurrence in MS/MS experiments, regardless of sequence. Our results confirm that substantial variation can be found at all levels, even when high‐quality identifications are used and the experimental conditions as well as the peptide sequences are kept constant. Finally, we discuss the observed variability in light of ongoing efforts to create spectral libraries and predictive software for target selection in targeted proteomics.
ADMET: Metathesis polycondensation
Authors: Opper Kathleen L. , Wagener Kenneth B.
Published: January 2011

Although it is well known that Acyclic Diene METathesis (ADMET) describes an olefin metathesis polymerization mode that relies on double‐bond substituent interchange of a diolefin, the story behind its discovery is not. The story is divulged here. Olefin metathesis has a rich history dating to the 1950s, but the one particular metathesis mode mentioned, ADMET, has more recent historical roots. ADMET polymerization is easy to do and highlighted here are the particular reaction details for success. Additionally, the most recent advances from the past 5 years are detailed, exemplifying this reaction's wide utility from fundamental structure–property studies to multiple advanced applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Vanadium alkoxide catalyzed polymerization of vinyl chloride
Authors: Tsuchiya Yoshikatsu , Endo Kiyoshi
Published: January 2011

The polymerization of vinyl chloride (VC) with vanadium complex/alkylaluminum catalyst was investigated. In the case of polymerization with vanadium oxytriethoxide (VO(OEt)3), poly(vinyl chloride) was obtained in a good yield. The effect of cocatalyst, solvent, and cocatalyst/precatalyst ratio was observed. The structure of the polymer obtained with VO(OEt)3/i‐Bu3Al catalyst consisted of regular head‐to‐tail sequence and isobutyl chain‐end structure. VO(OEt)3/alkylaluminum catalyst was able to copolymerize VC with styrene, 1‐butene, methyl methacrylate, and methyl acrylate. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Microwave‐assisted TCNE/TCNQ addition to poly(thienyleneethynylene) derivative for construction of donor–acceptor chromophores
Authors: Yuan Yuping , Michinobu Tsuyoshi , Ashizawa Minoru , Mori Takehiko
Published: January 2011

The alkyne moieties of poly(3‐hexylthienyleneethynylene) were reacted with tetracyanoethylene or 7,7,8,8‐tetracyanoquinodimethane by microwave irradiation to produce donor–acceptor chromophores in the polymer main chain. The resulting polymers were fully characterized by GPC, 1H NMR, and IR spectroscopies, and elemental analyses. They were both thermally and chemically stable, as revealed by thermogravimetric analyses and ESR measurements. UV–vis‐NIR spectroscopy revealed charge‐transfer bands in the low‐energy region, and electrochemistry confirmed the narrower band gaps with the elevated HOMO and lower LUMO levels relative to the precursor polymer. To take advantage of these postfunctionalization methods, p‐type doping of the polymers with I2 was attempted. Room temperature conductivities of the postfunctionalized polymers reached 4.5 × 10−5 S cm−1, which was about 10 times greater than that of the precursor polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Controlled polymerization of carbazole‐based vinyl and methacrylate monomers at ambient temperature: A comparative study through ATRP, SET, and SET‐RAFT polymerizations
Authors: Haridharan Neelamegan , Dhamodharan Raghavachari
Published: January 2011

The polymerization of N‐vinylcarbazole (NVK) and carbazole methacrylate (CMA) was carried out using controlled radical polymerization methods such as atom transfer radical polymerization (ATRP), single electron transfer (SET)‐LRP, and single electron transfer initiation followed by reversible addition fragmentation chain transfer (SET‐RAFT). Well‐controlled polymerization with narrow molecular weight distribution (Mw/Mn) < 1.25 was achieved in the case of NVK by high‐temperature ATRP while ambient temperature SET‐RAFT polymerization was relatively slow and controlled. In the case of CMA, SET‐RAFT is found to be more suitable for the ambient temperature polymerization. The polymerization rate followed first order kinetics with respect to monomer conversion and the molecular weight of the polymer increased linearly with conversion. The controlled nature of the polymerization is further demonstrated by the synthesis of diblock copolymers from PNVK and PCMA macroinitiators using a new flavanone‐based methacrylate (FMA) as the second monomer. All the polymers exhibited fluorescence. The excimer bands in the homopolymers of PNVK and PCMA were very broad, which may be attributed to the carbazole–carbazole overlap interaction. The scanning electron microscopy analysis of the block copolymer reveals interesting morphological features. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Sulfonated liquid crystalline polyesters as resin matrix for single wall carbon nanotube and nanodiamond composites
Authors: Sordi D. , De Ruijter C. , Orlanducci S. , Picken S. J. , Sudhölter E. J. R. , Terranova M. L. , de Smet L. C. P. M. , Dingemans T.J.
Published: January 2011

The focus of this study is on incorporating pendant sulfonate groups along the backbone of a liquid crystalline polyester (LCPE) with the aim to improve the dispersion of single wall carbon nanotubes (SWNTs) and nanodiamonds (NDs). Two LCPE matrices, one sulfonated (LCPE‐S) and one nonsulfonated reference polymer (LCPE‐R), were successfully synthesized via a melt condensation method using aromatic and aliphatic AB, AA, and BB‐type monomers. Upon the introduction of SWNT and ND particles, the glass transition temperature (Tg) of the sulfonated LCPE increased from 21.5 °C to 41.0 °C and 41.9 °C, for SWNTs and NDs, respectively. When sulfonate groups were absent, a decrease in Tg was observed. The storage modulus (E′) followed a similar trend, i.e., E′ increased from 1.3 GPa to 5.2 GPa and 3.4 GPa, upon the addition of NDs and SWNTs. The LCPE‐S showed a lower thermal stability due to the loss of sulfonate groups, i.e. the 5% weight loss temperature (T) is ∼280 °C for LCPE‐S vs. 333 °C for LCPE‐R. The decomposition temperature increased somewhat upon addition of the nanoparticles. The ability of dispersing carbon‐based nanostructures combined with an accessible melt processing window makes sulfonated LCPs attractive matrices towards preparing nanocomposites with improved thermal and mechanical properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.
Nitroxide‐mediated radical copolymerization of methyl methacrylate controlled with a minimal amount of 9‐(4‐vinylbenzyl)‐9H‐carbazole
Authors: Lessard Benoit , Ling Edwin Jee Yang , Morin Marie Sylvianne Thérèse , Marić Milan
Published: January 2011

The controlled nitroxide‐mediated homopolymerization of 9‐(4‐vinylbenzyl)‐9H‐carbazole (VBK) and the copolymerization of methyl methacrylate (MMA) with varying amounts of VBK were accomplished by using 10 mol % {tert‐butyl[1‐(diethoxyphosphoryl)‐2,2‐dimethylpropyl]amino} nitroxide relative to 2‐({tert‐butyl[1‐(diethoxyphosphoryl)‐2,2‐dimethylpropyl]amino}oxy)‐2‐methylpropionic acid (BlocBuilder™) in dimethylformamide at temperatures from 80 to 125 °C. As little as 1 mol % of VBK in the feed was required to obtain a controlled copolymerization of an MMA/VBK mixture, resulting in a linear increase in molecular weight versus conversion with a narrow molecular weight distribution (Mw/Mn ≈ 1.3). Preferential incorporation of VBK into the copolymer was indicated by the MMA/VBK reactivity ratios determined: rVBK = 2.7 ± 1.5 and rMMA = 0.24 ± 0.14. The copolymers were found significantly “living” by performing subsequent chain extensions with a fresh batch of VBK and by 31P NMR spectroscopy analysis. VBK was found to be an effective controlling comonomer for NMP of MMA, and such low levels of VBK comonomer ensured transparency in the final copolymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of reactive poly(norbornene): Ring‐opening metathesis polymerization of norbornene monomer bearing cyclic dithiocarbonate moiety
Authors: Sudo Atsushi , Morishita Hidetada , Endo Takeshi
Published: January 2011

A norbornene monomer bearing cyclic dithiocarbonate moiety (NB‐DTC) was successfully synthesized from the corresponding precursor having epoxy moiety by its reaction with carbon disulfide. NB‐DTC underwent the ring‐opening metathesis polymerization (ROMP) catalyzed by a ruthenium carbene complex to give the corresponding poly(norbornene). The dithiocarbonate moiety incorporated into the side chain of the obtained poly(norbornene) reacted with amine to afford the corresponding thiourethane moiety with thiol group, which underwent oxidative S‐S coupling and/or addition reaction to the C‐C double bond in the main chain, leading to formation of a cross‐linked polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.
Stimuli‐responsive micelles of amphiphilic AMPS‐b‐AAL copolymers in layer‐by‐layer films
Authors: Kellum Matthew G. , Harris Christopher A. , Mccormick Charles L. , Morgan Sarah E.
Published: January 2011

Aqueous reversible addition‐fragmentation chain transfer polymerization was used to synthesize poly(N‐[3‐(dimethylamino)propyl]acrylamide) (PDMAPA) cationic homopolymers and micelle‐forming, pH‐responsive, amphiphilic diblock copolymers of poly(sodium 2‐acrylamido‐2‐methyl‐1‐propanesulfonate‐block‐N‐acryloyl‐L‐alanine) (P(AMPS‐b‐AAL)). At low pH, the AAL blocks are protonated rendering them hydrophobic, whereas the AMPS blocks remain anionically charged because of the pendant sulfonate groups. Self‐assembly results in core–shell micelles consisting of hydrophobic cores of AAL and negatively charged shells of AMPS. Using solutions of these micelles with anionic coronas and of the cationic homopolymer PDMAPA, layer‐by‐layer (LbL) films were assembled at low pH, maintaining the micelle structures. Several block copolymers with varying AMPS and AAL block lengths were synthesized and used in the formation of LbL films. The thickness and morphology of the films were examined using ellipsometry and atomic force microscopy. The stimuli‐responsive behavior can be triggered by submersion of the film in water at neutral pH to disrupt the micelles. This behavior was monitored by observing the decrease in film thickness and alteration of the film morphology. The micelles were also loaded with a model hydrophobic compound, pyrene, and incorporated into LbL films. The release of pyrene from the films was monitored by fluorescence spectroscopy at varying pH values (1, 3, 5, and 7). As the pH of the solution increases, the rate of release increases. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Effects of double photoreactions on polycoumarate photomechanics
Authors: Yasaki Katsuaki , Suzuki Takuya , Yazawa Koji , Kaneko Daisaku , Kaneko Tatsuo
Published: January 2011

We established a polymerization condition of 3‐hydroxycinnamic acid, 3HCA, having photoreactive units over all the main chains. The polymers showed two types of photoreaction, that is, intramolecular E–Z isomerization and interchain [2 + 2] cycloaddition. Spectroscopic studies showed that the rate of the isomerization was higher than that of the cycloaddition. Although the original fiber was very brittle, the short‐time UV‐irradiation made the fiber softer and more elastic because the chain bending by the isomerization preferentially occurred. On the other hand, the long‐time irradiation made the fiber harder because of the cross‐linking by the cycloaddition, and simultaneously enhanced the elasticity. Besides we found that the cast film of P3HCA showed a photo‐bending behavior with the convex surface facing the UV‐lamp by the initial E–Z isomerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Optical switching, photophysical, and electrochemical behaviors of pendant triazole‐linked indolylfulgimide polymer
Authors: Nithyanandan Sivasankaran , Kannan Palaninathan , Senthil Kumar Karuppannan , Ramamurthy Perumal
Published: January 2011

Triazole‐linked 2‐indolylfulgimide polymer has been synthesized and its photochromic switching behavior has been characterized by NMR, IR, GPC, TGA, DSC, and UV–Vis spectroscopy. The synthesized photochromic polymer showed absorption peak maxima at 386 and 510 nm wherein the absorption at 510 nm was attributed to charge transfer from triazole ring nitrogen to carbonyl carbon of fulgimide unit. Fluorescence lifetime studies on exciting at 550 nm reveals triexponential behavior with fluorescence decay around 0.1, 1 and 4.2 ns, which correspond to open (E), closed (C) form of fulgimide and triazole ring, respectively. Whereas exciting at 470 nm evidences biexponential fit with fluorescence decay around 0.1 and 2.2 ns, which corresponds to the closed (C) form and triazole ring, respectively. Fluorescence decay of triazole ring was found to be influenced by the excitation wavelength. The cyclic voltammogram of open form of polymer depicts irreversible reductive wave at −1.4 V. On illumination with 360‐nm light, the reduction wave of polymer was shifted toward less cathodic wave at −0.9 V; this leads to formation of the closed form of fulgimide unit. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of electroactive polystyrene derivatives para‐substituted with π‐conjugated oligothiophene via postgrafting functionalization
Authors: Hu Zhaokang , Reichmanis Elsa
Published: January 2011

Two electroactive polystyrene derivatives para‐ substituted with π‐conjugated oligothiophene, poly(5‐hexyl‐5″‐(4‐vinylphenyl)‐2,2′:5′,2″‐terthiophene) (PH3TS), and poly(5‐hexyl‐5″″‐(4‐vinylphenyl)‐2,2′:5′,2″:5″,2″′:5″′,2″″‐quinquethiophene) (PH5TS) have been successfully synthesized via the Stille coupling reaction between tributyltin postfunctionalized poly(4‐(2‐thiophenyl)styrene) (PTS) and bromo‐oligothiophene. The effect of the chain length of the pendant oligothiophenes on properties of the resulting polymers including solubility, thermal stability, optical absorption, and electroactivation energy levels has been studied by using a variety of techniques such as thermogravimetric analyzer, differential scanning calorimetry, UV–Vis, Fluorescence, and cyclic voltammetry. With shielding of the hexyl terminal groups attached to the pendant oligothiophene units, no obvious chain aggregation was observed for both PH3TS and PH5TS even in a poor solvent environment. When compared with conventional linear conjugated polymer systems, the concept of grafting electroactive units as pendant side chains via postfunctionalizing aliphatic polymers might offer a strategy to precisely synthesize new electroactive polymer materials for a number of organic electronic applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Fluorine‐containing vinyl ether polymers: Living cationic polymerization in fluorinated solvents as new media and unique solubility characteristics in organic solvents
Authors: Shimomoto Hiroaki , Fukami Dai , Kanaoka Shokyoku , Aoshima Sadahito
Published: January 2011

Living cationic polymerization of fluorine‐containing vinyl ethers [CH2CHOC2H4OC3H6CnF2n+1: 5FVE (n = 2), 13FVE (n = 6)] was investigated in various solvents with a CH3CH(OiBu)OCOCH3/Et1.5AlCl1.5 initiating system in the presence of an added base. 5FVE was polymerized quantitatively in toluene at 0 °C, and the obtained polymers had predetermined molecular weights with narrow molecular weight distributions (Mw/Mn < 1.1). On the other hand, for the polymerization of 13FVE, the product polymers precipitated due to their extremely poor solubility in nonfluorinated organic solvents. Therefore, fluorinated solvents such as hydrochlorofluorocarbons, hydrofluorocarbons, hydrofluoroethers, or α,α,α‐trifluorotoluene, as‐yet uninvestigated for cationic polymerization, were employed. In these solvents, living polymerization was achieved even with 13FVE, yielding well‐defined polymers (Mw/Mn < 1.1, by size exclusion chromatography using a fluorinated solvent as an eluent). The solvents were also shown to be good for living polymerization of isobutyl vinyl ether. The obtained fluorine‐containing polymers underwent temperature‐responsive solubility transitions in organic solvents. Poly(5FVE) showed sensitive upper critical solution temperature (UCST)‐type phase separation behavior in toluene. Copolymers of 13FVE and isobutyl vinyl ether showed UCST‐type phase separation in common organic solvents with different polarities depending on their composition, while a homopolymer of 13FVE was insoluble in all nonfluorinated organic solvents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Simulation study of the equilibrium morphology in ionomers with different architectures
Authors: Allahyarov Elshad , Taylor Philip L.
Published: January 2011

The influence of the side chain and the backbone segment length on the shape of the hydrophilic clusters in an ionomer with sulfonate‐terminated side chains is investigated by molecular dynamics computer simulations. Different ionomer architectures, ranging from Nafion‐like molecules to ionomer structures with extremely long side chains and backbone segments, are analyzed. It is shown that the size and the sulfonate population of hydrophilic clusters are differently affected by the variation of the backbone length in homologous membranes. Although the clusters swell when the backbone length is increased, they contain fewer head groups, and the average sulfonate–sulfonate separation in these swollen clusters becomes larger. An increase in the equivalent weight (EW) of homologous membranes thus hinders proton transport through hydrophilic channels. We also have shown that larger sulfonate clusters are formed in modified membranes with longer side chains. Compared to the case of membranes with shorter side chains but the same EW, those with longer side chains have a higher proton diffusivity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
Application of empirical mode decomposition in the field of polymer physics
Authors: Kollengodu‐Subramanian Shankar , Srinivasan Babji , Zhao Jing , Rengaswamy Raghunathan , McKenna Gregory B.
Published: January 2011

Noisy data has always been a problem to the experimental community. Effective removal of noise from data is important for better understanding and interpretation of experimental results. Over the years, several methods have evolved for filtering the noise present in the data. Fast Fourier transform (FFT) based filters are widely used because they provide precise information about the frequency content of the experimental data, which is used for filtering of noise. However, FFT assumes that the experimental data is stationary. This means that: (i) the deterministic part of the experimental data obtained from a system is at steady state without any transients and has frequency components which do not vary with respect to time and (ii) noise corrupting the experimental data is wide sense stationary, that is, mean and variance of the noise does not statistically vary with respect to time. Several approaches, for example, short time Fourier transform (STFT) and wavelet transform‐based filters, have been developed to handle transient data corrupted with nonstationary noise (mean and variance of noise varies with respect to time) data. Both these approaches provide time and frequency information about the data (time at which a particular frequency is present in the signal). However, these filtering approaches have the following drawbacks: (i) STFT requires identification of an optimal window length within which the data is stationary, which is difficult and (ii) there are theoretical limits on simultaneous time and frequency resolution. Hence, filtering of noise is compromised. Recently, empirical mode decomposition (EMD) has been used in several applications to decompose a given nonstationary data segment into several characteristic oscillatory components called intrinsic mode functions (IMFs). Fourier transform of these IMFs identifies the frequency content in the signal, which can be used for removal of noisy IMFs and reconstruction of the filtered signal. In this work, we propose an algorithm for effective filtering of noise using an EMD‐based FFT approach for applications in polymer physics. The advantages of the proposed approach are: (i) it uses the precise frequency information provided by the FFT and, therefore, efficiently filters a wide variety of noise and (ii) the EMD approach can effectively obtain IMFs from both nonstationary as well as nonlinear experimental data. The utility of the proposed approach is illustrated using an analytical model and also through two typical laboratory experiments in polymer physics wherein the material response is nonstationary; standard filtering approaches are often inappropriate in such cases. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Radical‐cured block copolymer‐modified thermosets
Authors: Redline Erica M. , Francis Lorraine F. , Bates Frank S.
Published: January 2011

Poly(ethylene‐alt‐propylene)‐b‐poly(ethylene oxide) (PEP‐PEO) diblock copolymers were synthesized and added at 4 wt % to 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloxypropoxy)phenyl]propane (BisGMA), a monomer that cures using free radical chemistry. In separate experiments, poly(ethylene glycol) dimethacrylate (PEGDMA) was combined as a secondary monomer with BisGMA and the monomers were loaded with 4 wt % PEP‐PEO. The diblock copolymers self‐assembled into well‐dispersed spherical micelles with PEP cores and PEO coronas. No appreciable change in the final extent of cure of the thermosets was caused by the addition of diblock copolymer, except in the case of BisGMA, where the addition of the block copolymer increased extent of cure by 12%. Furthermore, the extent of cure was increased by 29% and 37% with the addition of 25 and 50 wt % PEGDMA, respectively. Elastic modulus and fracture resistance were also determined, and the values indicate that the addition of block copolymers does not significantly toughen the thermoset materials. This finding is surprising when compared with the large increase in fracture resistance seen in block copolymer‐modified epoxies, and an explanation is proposed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Solution processable high band gap hosts based on carbazole functionalized cyclic phosphazene cores for application in organic light‐emitting diodes
Authors: Soh Mui Siang , Santamaria Sonsoles Amor Garcia , Williams Evan Laurence , Pérez‐Morales Marta , Bolink Henk J. , Sellinger Alan
Published: January 2011

A new class of solution processable dendrimers based on cyclic phosphazene (CP) cores have been prepared and used as host materials for blue and green organic light emitting diodes (OLEDs). The dendrimers are prepared in high yield from minimal step reactions, are soluble in common solvents for solution processing, are amorphous, and have excellent thermal properties necessary for application in OLEDs. OLED efficiencies of 10.3 cd/A (4.2 lm/W) and 35.3 cd/A (33.5 lm/W) were achieved using commercially available FIrpic and Ir(mppy)3 as blue and green phosphorescent emitters, respectively. These efficiencies were 2× higher than control devices prepared using poly(N‐vinylcarbazole), the most commonly used host material in solution processed phosphorescent OLEDs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Synthesis of Liquid Organic Compounds from CH4 and CO2 in a Dielectric Barrier Discharge Operating at Atmospheric Pressure
Authors: Scarduelli Giorgina , Guella Graziano , Ascenzi Daniela , Tosi Paolo
Published: January 2011

Due to increasing attention to environmental problems, the conversion of methane and carbon dioxide into more useful chemicals represents an attractive goal. The present work reports on the formation of a liquid (20% in weight) during the dry reforming of methane in a dielectric barrier discharge at atmospheric pressure. Nuclear magnetic resonance spectroscopy allows to define the Methyl Branching Index, which estimates the amount of branching in the liquid material. The latter consists of a wide distribution of highly methyl‐branched, medium sized (15–25 carbon atoms) hydrocarbon molecules. Oxygenated compounds, mainly alcohols and ketones, are also present in the liquid sample.

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The Influence on Cell Growth Properties in Different Microtiterplate Types by Corona‐Dielectric Barrier Discharge Plasma at Atmospheric Pressure
Authors: Hähnel Marcel , Diener Annette , Kolukisaoglu Üner , Weltmann Klaus‐Dieter , Thurow Kerstin
Published: January 2011

In high throughput processes with living cells maintenance of sterility is a cost‐intensive but essential requirement. In the course of this work an atmospheric plasma process was developed for the sterilization of microtiterplates in such assays. In a next step it was necessary to investigate, if this plasma treatment changes surface properties for cell growth of different microtiterplate types. The results showed that this kind of plasma treatment did not significantly alter growth characteristics of different cell types in microtiterplates which were tissue culture treated or coated with collagen I or poly‐D‐lysine. Furthermore, these results revealed no detrimental effects of the applied corona‐dielectric barrier discharge (corona‐DBD) procedure on the tested surfaces and is therefore suitable for the sterilization of microtiterplates in automated cellular assays.

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Defect structure in Zn+ implanted Si: HRXRD study
Authors: Shcherbachev Kirill , Privezentsev Vladimir , Saraykin Vladimir , Podgornyy Dmitry
Published: January 2011

The defect structure of the layer damaged by implantation with 64Zn+ ions and its evolution during subsequent annealing was studied by high‐resolution X‐ray diffraction combined with secondary ion mass spectrometry and Auger electron spectroscopy methods. The samples were pieces of n‐type Si(001) wafer cut from a Czohralski grown ingot. The samples were implanted with 64Zn+ ions at an energy of 100 keV and an ion dose of 2 × 1014 cm−2 with subsequent annealing at 400 °C for 60 min and 700 °C for 10 min. The strain and Debye–Waller depth profiles determined from the diffraction patterns were analyzed and compared to Zn profiles. Annealing leads to significant changes in the shape of the profiles. These changes can be caused by annihilation of Frenkel pair components, redistribution of both radiation‐induced point defects and the implanted impurity, and quasi‐chemical reactions between point defects and implanted impurity. Analysis of Si(‐2‐24) reciprocal space maps confirms that the damaged layer remains fully coherent to the Si matrix in as‐implanted state and after the heat treatments. The increase of X‐ray diffuse scattering intensity after annealing is caused by clustering of radiation‐induced point defects and implanted Zn atoms.
Stability against hydrogen plasma exposure of Al‐doped zinc oxide thin film for a‐Si thin film solar cell
Authors: Yoo Hana , Lim Yong Hwan , Choi Bum Ho , Lee Jong Ho , Shin Dong Chan
Published: January 2011

In this study, the stability of Al‐doped zinc oxide (AZO) films under hydrogen (H2) plasma exposure was investigated. The plasma power was varied from 60 to 300 W, and the exposure time was also varied from 10 to 60 min to investigate the stability of the films against H2 plasma. Surface morphologies of the AZO films did not change much after H2 plasma exposure. The average optical transmittance was 87.4% at a plasma power of 60 W and decreased to 70.9% when the plasma power was 300 W. The electrical properties, including mobility and resistivity, were improved by plasma treatment. The characteristics of AZO films after H2 plasma exposure showed negligible differences in morphology and improved optical and electrical properties, which implies that the prepared AZO films have a strong resistance to H2 plasma exposure up to an RF power of 60 W for 20 minutes. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement in alignment of single‐walled carbon nanotubes grown on quartz substrate
Authors: Hata Kensuke , Ohno Yutaka , Kishimoto Shigeru , Mizutani Takashi
Published: January 2011

Aligned growth of single‐walled carbon nanotubes (SWNTs), which can be realized on a quartz substrate, is important for electron device applications such as high‐frequency transistors. In order to improve the alignment of the SWNTs, we studied pretreatments of the substrate before SWNT growth. When the surface of the quartz substrate was etched using hydrofluoric acid, the alignment and linearity of the grown SWNTs improved. This suggests that it is important to remove the uppermost layer on the surface of as‐received substrates, which is damaged due to the polishing process. We also studied an etching process to remove the damaged layer without increasing surface roughness (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carbon doping for p‐type GaP and GaPN in molecular beam epitaxy using carbon tetrabromide source
Authors: Liu Zhengxin , Kawanami Hitoshi , Sakata Isao
Published: January 2011

Carbon doping for p ‐type GaP and GaPN using carbon tetrabromide (CBr4) source in rf plasma molecular beam epitaxy was investigated. The doping concentration could be easily controlled by adjusting CBr4 pressure, and a wide region of hole concentration form ∼1017 to ∼1019 cm‐3 was obtained in both GaP and GaPN. It was found that the activation ratio of carbon in GaPN is lower than that in GaP. The hole concentration and mobility in GaPN do not change with nitrogen content at a wide region from 0.5 to 3%. The Hall mobility values in GaP and GaPN were ∼120 and ∼50 cm2/Vs at a hole concentration of ∼1 × 1017 cm‐3. Photoluminescence measurement show that the carbon incorporation reduces the intensity of luminescence, and the relative peak intensity decreases with the increase of hole concentration. This implies the existence of carbon‐related defects that quench the luminescence (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strain relaxation mechanism of InGaN thin film grown on m ‐GaN
Authors: Hanada Takashi , Shimada Taka‐aki , Ji Shi‐Yang , Hobo Kenji , Liu Yuhuai , Matsuoka Takashi
Published: January 2011

InGaN films were grown on off‐axis m ‐GaN substrates by metalorganic vapor phase epitaxy. Rocking curves of X‐ray diffraction around c‐axis revealed that Inx Ga1‐xN films incline to ±a1 direction when the film thickness and In composition x exceed a certain critical condition. The strain relaxation mechanism by introducing a2 and ‐a3 misfit dislocations at the interface is deduced from the ±a1 inclination. The rocking curves are reproduced fairly well by the scattering‐intensity calculations according to the atomic displacements caused by an array of the misfit dislocations, whose intervals are given by an asymmetric distribution function. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Device loading effect on nonresonant detection of terahertz radiation in dual grating gate plasmon‐resonant structure using InGaP/InGaAs/GaAs material systems
Authors: El Moutaouakil Amine , Suemitsu Tetsuya , Otsuji Taiichi , Videlier Hadley , Boubanga‐Tombet Stephane‐Albon , Coquillat Dominique , Knap Wojciech
Published: January 2011

We report on nonresonant detection of terahertz radiation using our original InGaP/InGaAs/GaAs plasmon‐resonant high‐electron‐mobility transistor having a dual grating gate (DGG) structure. The experiments were performed at room temperature using a Gunn diode operating at 0.30 THz as the THz source. Using a device‐loading model, the intrinsic responsivity was extracted and was dependent on the polarization of the incident THz wave. The device exhibited highest response when the electric‐field vector of the incident THz radiation was directed in the source‐drain direction. The 2D spatial distribution image of the transistor responsivity shows a clear beam focus centred on the transistor position, which proves the appropriate coupling of the THz radiation to the device, due to the DGG structure. The device also showed a high intrinsic responsivity of ∼90 V/W and a noise equivalent power (NEP) as low as ∼10‐10 WHz‐0.5. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of stochastic resonance response in a GaAs‐based nanowire field‐effect transistor
Authors: Kasai Seiya , Shiratori Yuta , Miura Kensuke , Nakano Yuta , Muramatsu Toru
Published: January 2011

Control of stochastic resonance (SR) response in a GaAs‐based nanowire FET is investigated for its application to nanoelectronics. The SR is a phenomenon in which the response to a weak signal is optimized by adding noise. Experiments clarify that the peak position is controlled by the gate offset voltage. The peak height also depends on the offset voltage and decreases when the peak position places in high noise region. Theoretical analysis indicates that the peak position depends only on the offset voltage whereas the height is also controlled by device dimensions. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
N‐doping induced band‐gap reduction in III‐V semiconductors: First‐principles calculations
Authors: Ishikawa Masato , Nakayama Takashi
Published: January 2011

Nitrogen doping often induces the band‐gap reduction for III‐V semiconductors. To understand its origin and feature, the chemical trend of reduction is studied by the first‐principles calculation with comparing the cases of various III‐V compounds. We found that III‐V semiconductors are categorized al least into two groups; the large band‐gap reduction occurs for InP, InAs, InSb, GaAs, and GaSb, while there is little reduction and appears a deep level of nitrogen in the band gap for AlAs, AlP, AlSb, and GaP. It is shown that such difference reflects the order of energy positions of host cation s‐orbital and the nitrogen 3s‐orbital states. Reflecting orbital hybridization originated from such difference, calculated optical spectra show different features near absorption edges (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhancement of terahertz detection efficiency in electro‐optical sampling using Fabry‐Perot microcavity structure
Authors: Shirai Hideto , Uzumi Keiji , Koshiba Shyun , Nakanishi Shunsuke , Itoh Hiroshi , Tsurumachi Noriaki
Published: January 2011

We have fabricated a Fabry‐Perot (FP) microcavity in the THz region with a GaP crystal as the cavity layer by using a simple stacking method. We utilized the FP cavity structure as the electro‐optic (EO) material for THz wave detection in the EO sampling of THz time domain spectroscopy. We observed three‐fold enhancement in the THz detection efficiency in the FP cavities as compared to the bare GaP crystal at the frequencies of resonant modes and stopband edges. This enhancement in THz detection efficiency is caused by the incidental THz electric field enhancement effect in the FP cavity. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
HVPE growth of AlN on trench‐ patterned 6H‐SiC substrates
Authors: Okumura Kenta , Nomura Takuya , Miyake Hideto , Hiramatsu Kazumasa , Eryuu Osamu
Published: January 2011

AlN films were grown on patterned SiC with stripes along the 〈1‐100〉 and 〈11‐20〉 directions by hydride vapor phase epitaxy and characterized by scanning electron microscope, atomic force microscopy and high‐resolution X‐ray diffraction. Although the critical thickness of AlN can be increased significantly using both patterns, AlN grown on 〈1‐100〉‐patterned SiC was more easily coalesced than that on the 〈11‐20〉 pattern. Moreover, the surface morphology and crystal quality of samples grown on 〈1‐100〉‐patterned SiC were better than those on 〈11‐20〉‐patterned substrates (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence spectra and carrier capture processes in sparsely‐spaced InAs quantum dot systems
Authors: Ohmori Masato , Vitushinskiy Pavel , Sakaki Hiroyuki
Published: January 2011

We have investigated photoluminescence (PL) spectra of sparsely‐spaced InAs self‐assembled quantum dots (QDs) in a GaAs matrix, grown by molecular beam epitaxy. The dot density of samples measured in this study ranges from 2×107 to 7.6×105 cm‐2. From the dot density dependence of PL intensity of the QDs and the wetting layer (WL), we have obtained the carrier capture radius of individual QD in the plane of the WL and found it to be 540 nm at 11 K. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐assembly formation of the magic ion of (H2O)20O+: observation of nanoscale cages of oxygenated water clusters induced from iron nanoparticles
Authors: Wu Hui‐Fen , Chin Chen‐Che , Liu Bo‐Min , Chen Yuan‐Chin , Lin Chi‐Hsien , Chang Kai‐Di , Lee Yi‐Hsien
Published: January 2011

For the first time, we observed a stable and intense ion (m/z 376) of the oxygenated water cluster ion ((H2O)20O+) produced from simply spraying an aqueous solution of iron nanoparticles (Fe NPs) into an electrospray mass spectrometry (ESI‐MS) system. Tandem mass spectrometric (MS/MS and MS/MS/MS) results were applied to identify the assignments of the fragment ions of m/z 376 in order to explore the possible structures of this cluster ion. The possible structures of the (H2O)20O+ ions are proposed as pentagonal dodecahedron water clathrate cages from the results of tandem mass spectrometry since eliminations of five water molecules were frequently observed in the MS/MS results for many subsequent fragment ions of m/z 376. The formation of this oxygenated water cluster ion ((H2O)20O+) in ESI‐MS is attributed to the high surface reactivity and surface energy of Fe NPs during ESI processes (under high temperature and high voltage (5 kV) of ESI spray environment). We believe that the observation of self‐assembly formation of oxygenated water clusters is an important issue in nanoscience as well as in the fields of water clusters. Copyright © 2011 John Wiley & Sons, Ltd.
Liquid chromatography/tandem mass spectrometry for analysis of 1,2‐dibromo‐4‐(1,2‐dibromoethyl)cyclohexane (TBECH) and 1,2,5,6‐tetrabromocyclooctane (TBCO)
Authors: Zhou Simon Ningsun , Reiner Eric J. , Marvin Chris H. , Helm Paul A. , Brindle Ian D.
Published: January 2011

Although the two flame retardants 1,2‐dibromo‐4‐(1,2‐dibromoethyl)cyclohexane (TBECH) and 1,2,5,6‐tetrabromocyclooctane (TBCO) have been widely used, a selective instrumental method of analysis for these compounds has not been developed to date. In this study, we demonstrate the feasibility to utilize liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the separation and analysis of α‐ and β‐TBCO and α‐, β‐, γ‐, and δ‐TBECH. Acetone was initially used in a tetrahedron solvent system for LC optimization. A simple isocratic elution allowed near‐baseline separation of these compounds. Different ionization approaches and mechanisms were investigated. The mass spectrometric transition of [M + O2]– => Br– (459.8 => 78.9) was a selective detection method for the target analytes. Good instrument detection limits (5 pg for γ‐/δ‐TBECH, 125 pg for α‐/β‐TBECH, and 30 pg for α‐/β‐TBCO with 2.0 µL injection) were obtained. Excellent linearity up to 50 ng/µL (R2 >0.999) was also achieved. This method has been applied to environmental samples (surface water) for screening purposes with recoveries ranging from 76–92% (CV%: 5–8%). This method shows significant improvement over previous methods. Copyright © 2011 John Wiley & Sons, Ltd.
A Fuzzy Logic Based Approach to Assess Sustainable Development of the Mining and Minerals Sector
Authors: Kommadath Basanth , Sarkar Runa , Rath Binayak
Published: January 2011

Assessing sustainable development, especially of the mining and minerals sector, is a challenge. This paper is an attempt to address this challenge by developing a methodology using fuzzy logic that encompasses the definitions, fundamentals, economic underpinnings and criteria of sustainable development. The paper starts by distinguishing the newly conceptualized ‘assessment for sustainability’ from the generally practiced ‘sustainability assessment’, framework, clarifying that the former looks at the process in question and lays out the path to be followed to assess sustainability, while the latter is just a static report. It then highlights the inherent limitations of the three traditional sustainability assessment tools and attempts to improve upon these limitations by proposing a model using fuzzy logic, weak sustainability criteria and context‐dependent sustainability indicators to assess sustainable development of the mining and minerals sector. As an illustration, the paper demonstrates how the proposed methodology can be applied to a reference town, where mining is the primary economic activity. The results derived can be used internally for identification of ‘hot spots’ as well as externally for sustainability reporting and stakeholder engagement. Assessment for sustainability also facilitates monitoring, estimating the degree of sustainability and defines a course of action for stakeholders as well as policy‐makers to improve a project's degree of sustainability. Copyright © 2011 John Wiley & Sons, Ltd and ERP Environment.
Entry into new niches: the effects of firm age and the expansion of technological capabilities on innovative output and impact
Authors: Kotha Reddi , Zheng Yanfeng , George Gerard
Published: January 2011

We provide evidence that young firms systematically differ from older firms in their innovative output when they enter ‘new to the firm’ technological niches. We analyze data from 128 biotechnology firms since their inception and track these firms over time. Our analyses reveal that the organizational age at which the firm branches into new technological niches significantly influences its innovative activity. We refine the focus of the extant literature by separately examining the effects of branching on the quantity of innovative output and the impact that this output has on the technology domain. Subsequent to branching into new niches, we find that older firms have a higher quantity of output than their younger counterparts, whereas young firms tend to outpace their older rivals with higher impact. We discuss the implications of these findings for the literature on dynamic capabilities and entrepreneurship. Copyright © 2011 John Wiley & Sons, Ltd.
When are assets complementary? star scientists, strategic alliances, and innovation in the pharmaceutical industry
Authors: Hess Andrew M. , Rothaermel Frank T.
Published: January 2011

To answer the question of when are assets complementary, we investigate specific resource combinations along the value chain, focusing on two mechanisms that are central to combining resources for innovation in the pharmaceutical industry: recruitment and retention of star scientists, and 2) engagement in strategic alliances. We propose that resource combinations that focus on the same parts of the value chain are substitutes due to knowledge redundancies. Conversely, we hypothesize that resource combinations that link different parts of the value chain are complements due to integration of nonredundant knowledge. To test these hypotheses, we empirically track the innovative performance of 108 global pharmaceutical firms over three decades (1974–2003). Copyright © 2011 John Wiley & Sons, Ltd.