bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved protein identification efficiency by mass spectrometry using N‐terminal chemical derivatization of peptides from Angiostrongylus costaricensis, a nematode with unknown genome
Authors: León Ileana R. , Neves‐Ferreira Ana G. C. , Valente Richard H. , Mota Ester M. , Lenzi Henrique L. , Perales Jonas 
Published: May 2007

AbstractMatrix‐assisted laser desorption ionization (MALDI), Peptide Mass Fingerprinting (PMF) and MALDI‐MS/MS ion search (using MASCOT) have become the preferred methods for high‐throughput identification of proteins. Unfortunately, PMF can be ambiguous, mainly when the genome of the organism under investigation is unknown and the quality of spectra generated is poor and does not allow confident identification. The post‐source decay (PSD) fragmentation of singly charged tryptic peptide ions generated by MALDI‐TOF/TOF typically results in low fragmentation efficiency and/or complex spectra, including backbone fragmentation ions (series b and y), internal fragmentation etc. Interpreting these data either manually and/or using de novo sequencing software can frequently be a challenge. To overcome this limitation when studying the proteome of adult Angiostrongylus costaricensis, a nematode with unknown genome, we have used chemical N‐terminal derivatization of the tryptic peptides with 4‐sulfophenyl isothiocyanate (SPITC) prior to MALDI‐TOF/TOF MS. This methodology has recently been reported to enhance the quality of MALDI‐TOF/TOF‐PSD data, allowing the obtainment of complete sequence of most of the peptides and thus facilitating de novo peptide sequencing. Our approach, consisting of SPITC derivatization along with manual spectra interpretation and Blast analysis, was able to positively identify 76% of analyzed samples, whereas MASCOT analysis of derivatized samples, MASCOT analysis of nonderivatized samples and PMF of nonderivatized samples yielded only 35, 41 and 12% positive identifications, respectively. Moreover, de novo sequencing of SPITC modified peptides resulted in protein sequences not available in NCBInr database paving the way to the discovery of new protein molecules. Copyright © 2007 John Wiley & Sons, Ltd.
Assessment and validation of the MS/MS fragmentation patterns of the macrolide immunosuppressant everolimus
Authors: Boernsen K. Olaf , Egge‐Jacobsen Wolfgang , Inverardi Bruno , Strom Tobin , Streit Frank , Schiebel Hans‐Martin , Benet Leslie Z. , Christians Uwe 
Published: May 2007

AbstractEverolimus (40‐O‐(2‐hydroxyethyl)rapamycin, Certican) is a 31‐membered macrolide lactone. In lymphocytes, it inhibits the mammalian target of rapamycin (mTOR) and is used as an immunosuppressant after organ transplantation. Due to its instability in pure organic solvents and insufficient HPLC separation, NMR spectroscopy analysis of its metabolite structures is nearly impossible. Therefore, structural identification based on tandem mass spectrometry (MS/MS) and MSn fragmentation patterns is critical. Here, we have systematically assessed the fragmentation pattern of everolimus during liquid chromatography (LC)‐electrospray ionization (ESI)‐MS/MS and validated the fragment structures by (1) comparison with structurally identified derivatives (sirolimus), (2) high‐resolution mass spectrometry, (3) elucidation of fragmentation pathways using ion trap mass spectrometry (up to MS5) and (4) H/D exchange. In comparison with the structurally related immunosuppressants tacrolimus and sirolimus, our study was complicated by the low ionization efficiency of everolimus. Detection of positive ions gave the best sensitivity, and everolimus and its fragments were mainly detected as sodium adducts. LC‐ESI‐MS/MS of everolimus in combination with collision‐induced dissociation (CID) resulted in a complex fragmentation pattern and the structures of 53 fragments were identified. These detailed fragmentation pathways of everolimus provided the basis for structural elucidation of all everolimus metabolites generated in vivo und in vitro. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesized substructural logics
Authors: Kamide Norihiro 
Published: May 2007

AbstractA mechanism for combining any two substructural logics (e.g. linear and intuitionistic logics) is studied from a proof‐theoretic point of view. The main results presented are cut‐elimination and simulation results for these combined logics called synthesized substructural logics. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Infinite games in the Cantor space and subsystems of second order arithmetic
Authors: Nemoto Takako , Ould MedSalem MedYahya , Tanaka Kazuyuki 
Published: May 2007

AbstractIn this paper we study the determinacy strength of infinite games in the Cantor space and compare them with their counterparts in the Baire space. We show the following theorems:1. RCA0 ⊢ $ \Delta^0_1 $‐Det* ↔ $ \Sigma^0_1 $‐Det* ↔ WKL0.2. RCA0 ⊢ ($ \Sigma^0_1 $)2‐Det* ↔ ACA0.3. RCA0 ⊢ $ \Delta^0_2 $‐Det* ↔ $ \Sigma^0_2 $‐Det* ↔ $ \Delta^0_1 $‐Det ↔ $ \Sigma^0_1 $‐Det ↔ ATR0.4. For 1 < k < ω, RCA0 ⊢ ($ \Sigma^0_2 $)k ‐Det* ↔ ($ \Sigma^0_2 $)k –1‐Det.5. RCA0 ⊢ $ \Delta^0_3 $‐Det* ↔ $ \Delta^0_3 $‐Det.Here, Det* (respectively Det) stands for the determinacy of infinite games in the Cantor space (respectively the Baire space), and ($ \Sigma^0_n $)k is the collection of formulas built from $ \Sigma^0_n $ formulas by applying the difference operator k – 1 times. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Understanding two‐sided persuasion: An empirical assessment of theoretical approaches
Authors: Eisend Martin 
Published: May 2007

AbstractThis study tries to evaluate empirically the validity and generality of causal models based on alternative theories and the integrative frame‐work provided by Crowley and Hoyer (1994) to explain the underlying persuasive mechanisms of two‐sided messages in marketing. In addition to an empirical test of the models, the study theoretically discusses and empirically explores suggestions for model modifications. Applying meta‐analytic‐based causal estimation, the results show that the parsimonious model based on attribution theory provides high generality and affirms the prevalent use of the theory in previous studies. All other models could be meaningfully improved by integrating alternative processes of less‐effortful message elaboration as suggested by dual‐process theories. The results suggest that the impact of argument quality in two‐sided messages is in line with previous models assuming effortful message elaboration, while less‐effortful elaboration processes seem to rely on the number of arguments used in two‐sided messages. © 2007 Wiley Periodicals, Inc.
Diffusion tensor MRI in rat models of invasive and well‐demarcated brain tumors
Authors: Kim Sungheon , Pickup Stephen , Hsu Oliver , Poptani Harish 
Published: May 2007

AbstractDiffusion tensor imaging (DTI) and its metrics, such as mean diffusivity (MD) and fractional anisotropy (FA), have been used to detect the extent of brain tumors and understand tumor growth and its influence on the surrounding tissue. However, there are conflicting reports on how DTI metrics can be used for tumor diagnosis. The physiological interpretation of these metrics in terms of tumor growth is also not clear. The objective of this study was to investigate the DTI parameters in two rat brain tumor models (9L and F98) with different patterns of aggressiveness by longitudinal monitoring of tumor growth and comparing the DTI parameters of these two tumor models. In addition to the standard DTI metrics, MD and FA, we measured other metrics representing diffusion tensor shape, such as linear and planar anisotropy coefficients (CL and CP), and orientational coherence measured by lattice index (LI), to characterize the two tumor models. The 9L tumor had higher FA, CL, and LI than the F98 tumor. F98 had a larger difference in anisotropies between tumor and peritumor regions than 9L. From the eigenvalues, it was found that the increase in CL and trace of the 9L tumor was due to an increase in the primary eigenvalue, whereas the increase in CP in the peritumor region was due to an increase in both primary and secondary eigenvalues and a decrease in tertiary eigenvalue. Our results indicate that shape‐oriented anisotropy measures, such as CL and CP, and orientational coherence measures, such as LI, can provide useful information in differentiating these two tumor models and also differentiating tumor from peritumoral regions. Copyright © 2007 John Wiley & Sons, Ltd.
Fast degradable poly(L‐lactide‐co‐ε‐caprolactone) microspheres for tissue engineering: Synthesis, characterization, and degradation behavior
Authors: Garkhal Kalpna , Verma Shalini , Jonnalagadda S. , Kumar Neeraj 
Published: May 2007

AbstractPolymeric scaffolds play a crucial role in engineering process of new tissues and effect the cell growth and viability. PLCL copolymers are found to be very useful during cell growth due to their elastic behavior and mechanical strength. Thus, low molecular weight PLCL copolymers of various ratios viz. PLCL(90/10), PLCL(75/25), PLCL(50/50) and PCL were synthesized by ring opening polymerization using stannous octoate as a catalyst. Synthesized polymers were characterized by GPC, 1H‐NMR, FTIR and XRD. The thermal properties of the copolymers were studied using TGA and DSC. Microspheres of about 100 μm diameter were prepared for different copolymers and their in vitro degradation behaviors were studied up to 108 days. It was observed that degradation of PLA content in polymer backbone occurs faster than PCL component which is also indicated by corresponding change in ratios of PLA/PCL, as determined by 1H‐NMR. SEM images of microspheres depicted the surface morphology during degradation and suggested the faster degradation for PLCL (50:50). Copolymers of different thermal, mechanical properties and different degradation behaviors can be prepared by adjusting the composition of copolymers. Various synthesized polymers from this work have been tested in our laboratory as polymeric scaffold for soft tissue engineering. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2755–2764, 2007
Nonisothermal crystallization behavior of poly(butylene adipate‐co‐terephthalate)/clay nano‐biocomposites
Authors: Chivrac Frédéric , Pollet Eric , Avérous Luc 
Published: May 2007

AbstractThe study of the nonisothermal crystallization behavior of layered silicates micro‐ and nano‐biocomposites based on poly(butylene adipate‐co‐terephthalate) (PBAT), a biodegradable copolyester, has been carried out with different theoretical models. They were applied and developed with the aim to describe and better understand the influence of the layered silicates dispersion on crystallization. The nucleation efficiency of the layered silicates has been demonstrated with the use of the “Modified Avrami model,” thanks to the higher crystallization rate parameter, Zc, and of the lower crystallization half‐time, t1/2, compared to the neat matrix. The crystallization activation energies, Ea, calculated from “Kissinger's model” have shown that layered silicates have a negative effect on the crystallite growth process. Thus, these analyses have shown that layered silicates have a double effect on the crystallization process. These two opposites' phenomena depend on the dispersion quality and are more pronounced for the intercalated nano‐biocomposites. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1503–1510, 2007
Immiscibility, upper critical solution temperature, and miscibility in blends of poly(vinyl ether)s with polyacrylics: Effects of pendant groups
Authors: Woo E. M. , Juang Yau‐Tsung 
Published: May 2007

AbstractVarious phase behavior of blends of poly(vinyl ether)s with homologous acrylic polymers (polymethacrylates or polyacrylates) were examined using differential scanning calorimetry, optical microscopy (OM), and Fourier‐transformed infrared spectroscopy. Effects of varying the pendant groups of either of constituent polymers on the phase behavior of the blends were analyzed. A series of interestingly different phase behavior in the blends has been revealed in that as the pendant group in the acrylic polymer series gets longer, polymethacrylate/poly(vinyl methyl ether) (PVME) blends exhibit immiscibility, upper critical solution temperature (UCST), and miscibility, respectively. This study found that the true phase behavior of poly(propyl methacrylate)/PVME [and poly(isopropyl methacrylate)/PVME)] blend systems, though immiscible at ambient, actually displayed a rare UCST upon heating to higher temperatures. Similarly, as the methyl pendant group in PVE is lengthened to ethyl (i.e., PVME replaced by PVEE), phase behavior of its blends with series of polymethacrylates or polyacrylates changes correspondingly. Analyses and quantitative comparisons on four series of blends of PVE/acrylic polymer were performed to thoroughly understand the effects of pendant groups in either polyethers (PVE's) or acrylic polymers on the phase behavior of the blends of these two constituents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1521–1534, 2007
Synthesis and characteristics of a novel silicon‐containing flame retardant and its application in poly[2,2‐propane‐(bisphenol)carbonate]/acrylonitrile butadiene styrene
Authors: Zhong Hanfang , Wei Ping , Jiang Pingkai , Wu Dan , Wang Genlin 
Published: May 2007

AbstractNovel halogen‐free compounds [9,10‐dihydro‐9‐oxa‐10‐phosphaphanthrene‐10‐oxide/vinyl methyl dimethoxysilane/N‐β‐(aminoethyl)‐γ‐aminopropyl methyl dimethoxysilane (DOPO–VMDMS–NMDMS)] that simultaneously contain phosphorus, nitrogen, and silicon have been synthesized through the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphanthrene‐10‐oxide (DOPO), vinyl methyl dimethoxysilane (VMDMS), and N‐β‐(aminoethyl)‐γ‐aminopropyl methyl dimethoxysilane (NMDMS). The chemical structure and properties of DOPO–VMDMS–NMDMS have been investigated with Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, phosphorous nuclear magnetic resonance, and thermogravimetric analysis (TGA). These synthesized flame retardants have been blended with a poly[2,2‐propane‐(bisphenol) carbonate]/acrylonitrile butadiene styrene (PC/ABS) alloy. The flame‐retardant properties of these mixture samples have been estimated with the limiting oxygen index (LOI), and the thermal stability has been characterized with TGA. The LOI value of PC/ABS/DOPO–VMDMS–NMDMS is enhanced up to 27.2 vol % from 21.2 vol %, and the char yield is also improved slightly (from 12 to 17%) with 2.8 wt % phosphorus, 3.0 wt % silicon, and 0.5 wt % nitrogen (at a 30 wt % loading of DOPO–VMDMS–NMDMS). The results show that there is a synergistic effect of the elements phosphorus, silicon, and nitrogen on the flame retardance. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1542–1551, 2007
Effect of cosolvent on solid phase transitions of α‐ to β‐form crystal of syndiotactic polystyrene occurred in supercritical Co2 containing solvent
Authors: Liao Xia , He Jiasong , Zhang Jun , Ma Weiming 
Published: May 2007

AbstractThe solid phase transition mechanism of α‐ to β‐form crystal upon specific treating with supercritical CO2 + cosolvent on original pure α and mixed (α+β) form syndiotactic polystyrene (sPS) was investigated, using wide angle X‐ray diffraction and differential scanning calorimetry measurements as a function of temperature, pressure, and cosolvent content. As in the supercritical CO2, sPS in supercritical CO2 + cosolvent underwent solid phase transitions from α‐ to β‐form, and higher temperature or higher pressure favored this transformation. Due to the higher dipole moment of acetone, small amounts of acetone used as cosolvent with CO2 made the transition of α‐ to β‐form occur at lower temperature and pressure than in supercritical CO2, and made the α‐form crystal completely transform to β‐form in the original mixed (α+β) form, whereas ethanol did not. The original β‐form crystal in the original mixed (α+β) form sample acted as the nucleus of new β‐form crystal in the presence of cosolvent as it did in supercritical CO2, when compared with the original pure α‐form sample. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1625–1636, 2007
The regional distribution of mountain permafrost in Iceland
Authors: Etzelmüller Bernd , Farbrot Herman , Guðmundsson Águst , Humlum Ole , Tveito Ole Einar , Björnsson Helgi 
Published: May 2007

AbstractA regional map of permafrost distribution in Iceland was developed based on meteorological data. The regional model was calibrated with ground surface temperature data and tested using ground temperature data from four shallow boreholes and a rock glacier inventory. The results indicate widespread mountain permafrost at elevations above 800–900 m a.s.l. in northern and eastern Iceland. According to the regional map, the mountain permafrost zone covers c. 8000 km2 which is about 8% of the country's land area. Copyright © 2007 John Wiley & Sons, Ltd.
Probing the transverse magneto‐optical Kerr effect at the nanoscale
Authors: Alvarez‐Prado L.‐M. , Souche Y. , Carminati R. 
Published: May 2007

AbstractThis article presents a theoretical formalism for a magneto‐optical scanning near‐field microscope (MO‐SNOM) in the transverse magneto‐optical Kerr effect configuration. Polarized light emitted by a nanosource is scattered by the magnetic object towards the detector. The nanosource is modelled as a circular aperture in an infinitely thin, perfectly conducting screen following the Bethe–Bouwkamp model. The theorem of reciprocity is used for calculating the detected signal in a constant‐height scanning mode for a Co thin film pattern. Two magnetic distributions are investigated: the single domain and the Bloch wall. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gaussian quantum dots of type II in in‐plane electric field
Authors: Krasnyj J. , Tytus M. , Donderowicz W. , Jacak W. , Chuchmala A. 
Published: May 2007

AbstractThe growing interest is recently focusing on QDs of type II, which contrary to type I QDs attract electrons and repulse holes (or conversely). In such QDs an electron–hole pair (X exciton) can still be traped due to electron–hole Coulomb attraction, resulting in significantly more complex structure of excitonic states. We consider an X exciton in QD of type II defined by electrostatic focusing in a narrow quantum well, in the presence of additional external in‐plane electric field. The dependence of PL spectrum on dot size and in‐plane electric field is analysed within the Hartree approach for model planar Gaussian confinement. The exciton ground state and its energy red‐shift are found as a function of electric field and dot size. Corresponding rearrangement of PL spectrum is described. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescent silicon nanostructures synthesized by laser ablation
Authors: Riabinina D. , Durand C. , Rosei F. , Chaker M. 
Published: May 2007

AbstractThis paper describes the properties of silicon nanostructures synthesized by laser ablation. This is an extremely flexible technique allowing the fabrication of different kinds of nanostructures including porous films and Si nanocrystals embedded in Si oxide. Quantum confinement effects in nanostructures of indirect bandgap semiconductors have attracted great interest due to their new optical properties. This improvement of the efficiency of silicon in emitting light is a first step towards the integration of silicon in optoelectronics. Many groups are working on developing fabrication methods of Si nanocrystals and on the optimization of their luminescence properties. In particular, we describe in detail the mechanisms that govern nucleation and growth of these photoluminescent nanostructures. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rapid separation and identification of phenolic and diterpenoid constituents from Radix Salvia miltiorrhizae by high‐performance liquid chromatography diode‐array detection, electrospray ionization time‐of‐flight mass spectrometry and electrospray ionization quadrupole ion trap mass spectrometry
Authors: Zhu Zhenyu , Zhang Hai , Zhao Liang , Dong Xin , Li Xiang , Chai Yifeng , Zhang Guoqing 
Published: May 2007

AbstractHigh‐performance liquid chromatography‐diode array detection (HPLC‐DAD), electrospray ionization time‐of‐flight mass spectrometry (HPLC‐ESI‐TOF‐MS) and electrospray ionization quadrupole ion trap mass spectrometry (HPLC‐ESI‐MSn) were used for the isolation, identification and structural analysis of water‐soluble phenolic and nonpolar diterpenoid constituents in Dan‐shen (Radix Salvia miltiorrhizae) which was prepared by sonication in 70% methanol. Mass spectra were obtained by ESI‐TOF‐MS and electrospray ionization quadrupole ion trap mass spectrometry (ESI‐QIT‐MS). A formula database of known constituents in Dan‐shen was established and most constituents were rapidly identified by HPLC‐DAD/ESI‐TOF‐MS by matching their accurate molecular masses with the formulae of the compounds in the database. Compounds with the same molecular formula could not be differentiated by TOF‐MS; however, QIT‐MS could differentiate those compounds and elucidate their structures based on their characteristic fragmentation. HPLC‐DAD, HPLC/ESI‐TOF‐MS and HPLC/ESI‐MSn provided complementary information for the identification of the constituents in Dan‐shen. Forty constituents were identified in 30 min based on their positive and negative ion ESI mass spectra and liquid chromatographic information. Thus the method described is useful for the rapid analysis of multiple constituents in Dan‐shen. Copyright © 2007 John Wiley & Sons, Ltd.
Identification and quantitation of pyrethroid pesticide residues in vegetables by solid‐phase extraction and liquid chromatography/electrospray ionization ion trap mass spectrometry
Authors: Chen Tianwen , Chen Guonan 
Published: May 2007

AbstractA quantitative method consisting of solid‐phase extraction (SPE) followed by liquid chromatography/electrospray ionization ion trap mass spectrometry (LC/ESI‐ITMS) analysis was developed for the identification and quantitation of ten pyrethroid pesticides commonly used in vegetables. The best HPLC separation was achieved using a gradient program of methanol/water mixture. For the vegetable samples, an SPE procedure to clean up the matrices was carried out prior to LC/MS analysis. Under the optimum conditions, the limits of quantification of the pyrethroid pesticides (tetramethrin, allethrin, fenpropathrin, lambda‐cyhalothrin, cypermethrin, deltamethrin, fenvalerate, bioresmethrin, permethrin and bifenthrin) ranged from 0.03 to 0.1 mg kg−1 with relative standard deviations <20%, and the mean recoveries ranged from 69.5 to 102.5%. The proposed method has been successfully applied to the determination of pyrethroids in six vegetables with satisfactory results. Copyright © 2007 John Wiley & Sons, Ltd.