bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methanol vinylation mechanism in the KOH/DMSO/CH3OH/C2H2 system
Authors: Vitkovskaya Nadezhda M. , Larionova Elena Yu. , Kobychev Vladimir B. , Kaempf Natalia V. , Trofimov Boris A. 
Published: June 2010

AbstractThe reaction mechanism of methanol vinylation with acetylene involving a nondissociated KOH molecule was studied using the MP2/6‐311++G**//HF/6‐31+G* approach with the DMSO molecule explicitly included into reaction system. The whole conversion cycle of methanol vinylation including active nucleophile generation, bonding of the latter to the acetylene moiety yielding an intermediate carbanion, final methyl vinyl ether formation, and potassium hydroxide regeneration could be realized in the coordination shell of nondissociated KOH. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Geometry and vibrational frequencies of the helical polypeptide complexes with ligand molecules
Authors: Makshakova Olga , Chachkov Denis , Ermakova Elena 
Published: June 2010

AbstractThe complexes of alpha helical polypeptides and individual molecules of water, acetonitrile, and 1,4‐dioxane have been investigated. We used 16‐mer of polyalanine (PA), polyglutamic acid (PGA) and poly‐γ‐benzyl‐L‐glutamate (PBG). Full geometry optimization was performed for polypeptides and their complexes with ligands, each structure has been characterized by the vibrational analysis and the interaction energy including the correction for zero point vibrational energy. Polyalanine creates by single complex with water molecule, acetonitrile, and dioxane. Polyglutamic acid forms five different complexes with water molecule, and three complexes with acetonitrile and two complexes with dioxane. Two complexes of poly‐γ‐benzyl‐L‐glutamate with each ligand were found. Carbonyl oxygen of PGA and PBG confirms its strong acceptor character by participation in formation of all obtained complexes with water and acetonitrile. The long side chains of PGA and PBG aid the formation of complexes with two hydrogen bonds where ligand molecule bridges two polar sites of polypeptide. Most of complexes of dioxane with polypeptides are produced due to weak hydrogen bonds of type CH···O. Strong shifts for the stretching vibrations of the interacting group of polypeptides and ligands under the complex formation are detected. Obtained frequencies are in a good agreement with known experimental data. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
New nonsteroidal anti‐inflammatory molecules with reduced photodegradation side effects and enhanced COX‐2 selectivity
Authors: Musa Klefah A. K. , Palwai Viraja R. , Eriksson Leif A. 
Published: June 2010

AbstractNonsteroidal anti‐inflammatory drugs (NSAIDs) are widely used as antipyretic, analgesic, and anti‐inflammatory agents. However, they are also associated with a range of side effects, from phototoxicity due to excited state induced decarboxylation to severe conditions in the gastrointestinal tract caused by inhibition of the COX‐1 isoform of the target cyclooxygenase enzyme. In the current work, new derivatives of the three NSAIDs ketoprofen, ibuprofen, and naproxen were designed. Their photochemistry was explored using hybrid‐density functional theory (B3LYP/6‐31G(d,p)) and time‐dependent (TD) DFT, showing that the compounds will have significantly reduced propensity to decarboxylate from the first excited triplet state. In addition, docking studies were carried out for these new molecules to explore their activity and selectivity toward the two isoforms of the COX enzyme. The results show that most compounds have increased activity toward the COX enzymes, and in general are more selective toward the COX‐2 target isoform. The results from this study suggest that the new modified molecules could be used in the future as NSAIDs with considerably reduced side effects. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Modeling solvatochromism of Nile red in water
Authors: Murugan Natarajan Arul , Rinkevicius Zilvinas , Ågren Hans 
Published: June 2010

AbstractSpurred by the pioneering modeling studies of Sylvio Canuto on absorption spectra and solvatochromic shifts of organic molecules in polar and nonpolar solvents, we report in this work a computational study for the common optical dye probe Nile red (NR) to elucidate the origin of its absorption shift between gas phase and aqueous solution. The Car‐Parrinello molecular dynamics (CPMD) technique is used for gas phase NR, whereas for NR in water solvent, a hybrid quantum mechanics‐molecular dynamics (CPMD‐QM/MM) approach has been utilized. For the configurations obtained from CPMD and CPMD‐QM/MM, the absorption spectrum has been calculated using the INDO/CIS method as implemented in the ZINDO program. Different solvation shells for NR in water have been defined based on solute‐all‐atoms and solvent center of mass radial distribution function (g(rX–O)rdf). The electronic excitation energies for these solvation shells were calculated in a systematic way to evaluate their individual contributions. In addition, calculations of absorption spectra were performed for NR (excluding solvent molecules) obtained from CPMD‐QM/MM calculations to isolate the contribution to the solvatochromic shift just due to solvent‐induced geometrical change. Interestingly, this geometrical change in NR itself contributes as much as 50 nm to the solvatochromic shift. The calculated λmax for gas phase is around 488 nm and is comparable to the values reported for NR in nonpolar solvents, whereas the inclusion of solvent molecules in the hydration shell yields a λmax of 565 nm which contributes to almost 77 nm of the solvatochromic shift. The inclusion of solvent molecules up to the fourth solvation shell in the g(rX–O) rdf yields λmax of 596 nm which is in good agreement with the experimentally reported value 593 nm. The change in λmax due to inclusion of the fourth solvation shell is only 1 nm, indicating that the spectrum has converged with respect to the solvent effect. Overall, this study suggests that the combined use of CPMD‐QM/MM and ZINDO can be successfully used to model and to interpret solvatochromic and thermochromic behavior of NR and other organic dye molecules. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Nonadiabatic effects in the irradiation of ethylene
Authors: Wang Zhi‐Ping , Dinh Phuong Mai , Reinhard Paul Gerhard , Suraud Eric , Zhang Feng Shou 
Published: June 2010

AbstractIn the framework of the time‐dependent local density approximation, applied to valence electrons, coupled nonadiabatically to molecular dynamics of ions, the irradiations of ethylene by laser and fast charged projectiles are studied. We find that the Coulomb fragmentation sensitively depends on the laser frequency and on the charge of the projectile. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Isomerization effects on chemical shifts and spin‐spin coupling constants of polyacetylene chains: A GIAO‐DFT study
Authors: Colherinhas G. , Fonseca T. L. , Georg H. C. , Castro M. A. 
Published: June 2010

AbstractUsing the gauge‐including atomic orbitals approach with B3LYP exchange‐correlation functional in combination with the 6‐311++G(2d,2p) basis set, we have calculated the 13C chemical shifts [Δσ] and 13C13C indirect spin‐spin coupling constants [J(C,C)] for the series of isolated planar polyacetylene chains C2nH2n+2, from n = 2 up to n = 11. For both cis and trans isomers, infinite polymer values can be estimated from converged chemical shifts in the central unit of each isomer. The theoretical model predicts the chemical shift difference between the cis and trans forms of 10.28 ppm, in very good concordance with experimental result. The 1J(CC) and 1J(CC) calculated values are more geometry‐dependent but they exhibit notable regularity typical for such systems as the size of chain is increased. Variations between 1J(CC) and 1J(CC) in the central unit of the C22H24 chain are estimated around 11 Hz, independent of isomeric form. It is found for both 1J(CC) and 1J(CC) that variations between the cis and trans forms are in the range of 3–4 Hz, indicating also a distinction of the isomeric form. In addition, our results show that the presence of a structural change on these conjugated backbones has marked influence on the chemical shifts. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Filtered stress autocorrelation functions of liquid water models
Authors: Medina J. S. , Prosmiti R. , Villarreal P. , Delgado‐Barrio G. , Alemán J. V. , González B. , Winter G. 
Published: June 2010

AbstractPressure autocorrelation functions of two models, SPC/E and SPC/Fw, of pure liquid water are presented. Periodic boundary condition simulations, in the microcanonical ensemble (NVE), of 256 molecules at room temperature are accomplished for both models. Green‐Kubo relations are used over the stress tensor time series to extract viscosity properties of the system. Filtering of noise and signal in the numerical data is considered. Three steps are discussed to reach relevant physical data pertaining to transport coefficients calculations: (1) removing noise via Savitzky‐Golay filters to smooth signals, (2) fitting data by combining Kohlrausch type functions, (3) separating low frequency from high frequency behavior. On the latter resides the essential difference between rigid and flexible models. Considerations about the stress tensor structure in flexible case, and the physical meaning each part holds, are explained and used to show similarities in low frequency (librational/translational and cluster) motions present in both models. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Determination of nandrolone metabolites in human urine: comparison between liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry
Authors: Buiarelli Francesca , Giannetti Luigi , Jasionowska Renata , Cruciani Claudia , Neri Bruno 
Published: June 2010

AbstractNandrolone (19‐nortestosterone) is an androgenic anabolic steroid illegally used as a growth‐promoting agent in animal breeding and as a performance enhancer in athletics. Therefore, its use was officially banned in 1974 by the Medical Commission of the International Olympic Committee (IOC). Following nandrolone administration, the main metabolites in humans are 19‐norandrosterone, 19‐norethiocolanolone and 19‐norepiandrosterone, and their presence in urine is the basis of detecting its abuse. The present work was undertaken to determine, in human urine, nandrolone metabolites (phase I and phase II) by developing and comparing multiresidue liquid chromatography/tandem mass spectrometry (LC/MS/MS) and gas chromatography/mass spectrometry (GC/MS) methods. A double extraction by solid‐phase extraction (SPE) was necessary for the complete elimination of the interfering compounds. The proposed methods were also tested on a real positive sample, and they allow us to determine the conjugated/free fractions ratio reducing the risk of false positive or misleading results and they should allow laboratories involved in doping control analysis to monitor the illegal use of steroids. The advantages of LC/MS/MS over GC/MS (which is the technique mainly used) include the elimination of the hydrolysis and derivatization steps: it is known that during enzymatic hydrolysis several steroids can be converted into related compounds and deconjugation is not always 100% effective. The validation parameters for the two methods were similar (limit of quantification (LOQ) <1 ng/mL and percentage coefficient of variance (CV%) <16.4), and both were able to confirm unambiguously all the analytes, thus confirming the validity of both techniques. Copyright © 2010 John Wiley & Sons, Ltd.
Semi‐online nanoflow liquid chromatography/matrix‐assisted laser desorption ionization mass spectrometry of synthetic polymers using an octadecylsilyl‐modified monolithic silica capillary column
Authors: Watanabe Takehiro , Nakanishi Keisuke , Ozawa Tomoyuki , Kawasaki Hideya , Ute Koichi , Arakawa Ryuichi 
Published: June 2010

AbstractWe have designed a semi‐online liquid chromatography/matrix‐assisted laser desorption/ionization mass spectrometry (LC/MALDI‐MS) system to introduce eluent from a octadecylsilyl (ODS) group modified monolithic silica capillary chromatographic column directly onto a sample plate for MALDI‐MS analysis. Our novel semi‐online system is useful for rapidly and sensitively examining the performance of a monolithic capillary column. An additional advantage is the small elution volume of a monolithic capillary column, which allows delicate eluents, such as 1,1,1,3,3,3,‐hexafluoroisopropyl alcohol (HFIP), to be used to achieve cost‐effective analysis. Using the semi‐online LC/MALDI‐MS system, chromatographic separation of polymers by the monolithic column with different eluents was studied. Separation of poly(methyl methacrylate) and Nylon 6/6 showed that the column functioned via size‐exclusion separation when tetrahydrofuran or HFIP eluent was used. On the other hand, the separation behavior of Nylon 11 indicated a reversed‐phase mode owing to the interaction of the polymer with the modified ODS group in the column. Using tetrahydrofuran/methanol (1:1, v/v) as the eluent, the LC/MALDI‐MS spectra of poly(lactic acid), which contains both linear and cyclic polymer structures, showed that the column could separate the hydrophobic cyclic polymer and elute it out relatively slowly. The monolithic column functions basically via size‐exclusion separation; the reversed‐phase separation by interaction with the ODS functions may have less influence on column separation. The semi‐online monolithic capillary LC/MALDI‐MS method we have developed should provide a means of effectively analyzing synthetic polymers. Copyright © 2010 John Wiley & Sons, Ltd.
Sensitive liquid chromatography/tandem mass spectrometry assay for absolute quantification of ITIH4‐derived putative biomarker peptides in clinical serum samples
Authors: van den Broek Irene , Sparidans Rolf W. , Schellens Jan H. M. , Beijnen Jos. H. 
Published: June 2010

AbstractTo explore the potential of peptide fragments derived from inter‐α‐trypsin inhibitor heavy chain‐4 (ITIH4) as serum markers for different cancer types, sensitive and specific analytical assays are required. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) would be suitable; however, a previously developed method for quantification of eight ITIH4 fragments (ITIH4‐21, ‐22, ‐25, ‐26, ‐27, ‐28, ‐29 and ‐30) was found to be insensitive for clinical use. A more sensitive LC/MS/MS assay has now been developed and validated, which was further optimized to facilitate analyses of large sets of clinical serum samples. Benefits compared to the previous method include reduction of sample volume (100 µL), omission of protein precipitation and evaporation and transferring solid‐phase extraction (SPE) to a 96‐well format. Chromatographic separation on an XBridge BEH300 C18 column, using a water/methanol gradient containing acetic acid, was coupled to triple quadrupole mass spectrometric detection, applying heated electrospray ionization. Method validation revealed deviations from nominal concentrations below 10.1% and intra‐ and inter‐assay precisions below 17.4 and 20.0%, respectively, at the lower limit of quantification (LLOQ) for all peptides. The reported changes resulted in more rapid and efficient analyses and reduced LLOQs for the six less abundant peptides (1.2; 1.0; 1.2; 2.0; 2.0 and 2.0 ng/mL vs. 2.1; 2.0; 2.5; 2.6; 2.2 and 2.4 ng/mL for ITIH4‐21, ‐22, ‐25, ‐27, ‐28 and ‐29, respectively). The method has shown its applicability by quantifying all peptides in appropriate concentration ranges in serum from healthy volunteers and application to clinical samples from breast cancer patients. Copyright © 2010 John Wiley & Sons, Ltd.
Extra virgin (EV) and ordinary (ON) olive oils: distinction and detection of adulteration (EV with ON) as determined by direct infusion electrospray ionization mass spectrometry and chemometric approaches
Authors: de O. Alves Júnia , Neto Waldomiro B. , Mitsutake Hery , Alves Paulo S. P. , Augusti Rodinei 
Published: June 2010

AbstractExtra virgin (EV), the finest and most expensive among all the olive oil grades, is often adulterated by the cheapest and lowest quality ordinary (ON) olive oil. A new methodology is described herein that provides a simple, rapid, and accurate way not only to detect such type of adulteration, but also to distinguish between these olive oil grades (EV and ON). This approach is based on the application of direct infusion electrospray ionization mass spectrometry in the positive ion mode, ESI(+)‐MS, followed by the treatment of the MS data via exploratory statistical approaches, PCA (principal component analysis) and HCA (hierarchical clustering analysis). Ten distinct brands of each EV and ON olive oil, acquired at local stores, were analyzed by ESI(+)‐MS and the results from HCA and PCA clearly indicated the formation of two distinct groups related to these two categories. For the adulteration study, one brand of each olive oil grade (EV and ON) was selected. The counterfeit samples (a total of 20) were then prepared by adding assorted proportions, from 1 to 20% w/w, with increments of 1% w/w, of the ON to the EV olive oil. The PCA and HCA methodologies, applied to the ESI(+)‐MS data from the counterfeit (20) and authentic (10) EV samples, were able to readily detect adulteration, even at levels as low as 1% w/w. Copyright © 2010 John Wiley & Sons, Ltd.
Vision‐based robotic person following under light variations and difficult walking maneuvers
Authors: Tarokh Mahmoud , Merloti Paulo 
Published: June 2010

AbstractThe paper addresses the problem of robotic person following indoors and outdoors with significant light variation such as moving from sunny areas into shade and difficult walking maneuvers such as jumping to the side or making sharp turns. These are achieved through certain image processing techniques and by real‐time control of camera parameters affecting the light exposure, i.e., camera gain and shutter speed. Several strategies are also formulated and integrated to quickly recognize and segment the person from the environment during difficult walking maneuvers. The centroid of a person's image, which is a critical quantity for person following, is determined using a new method based on aggregation of the detected regions and their color characteristics. In addition to the camera exposure control, the camera pan and tilt and the robot speed and steering are controlled using the characteristics of the detected person's image such as mass (area) and centroid. Although the emphasis of the paper is on person following, the same techniques can be adapted for following moving objects such as another robot or a car. The system has been implemented on a Segway robotic platform that has been equipped with a camera, an onboard computer, loudspeakers, game pad, etc. Extensive trials have been carried out both indoors and outdoors, and a video has been prepared that shows person following under a variety of conditions. © 2010 Wiley Periodicals, Inc.
Comparison of the interannual and interdecadal variability of heavy flood characteristics upstream and downstream from dams in inversed hydrologic regime: Case study of Matawin River (Québec, Canada)
Authors: Fortier Catherine , Assani Ali A. , Mesfioui Mhamed , Roy André G. 
Published: June 2010

AbstractErected in 1930, the Matawin Dam caused an inversion of the hydrologic regime of the Matawin River: snow‐melt water in spring (April to June) is stored in the reservoir and then released in winter (January to March) to feed the hydroelectric generating stations built downstream on the Saint‐Maurice River. Thus, heavy floods occur upstream from the dam in spring but downstream in winter. We compared the interannual and interdecadal variability of the heavy flood characteristics (magnitude, duration, frequency and variability) both upstream (spring floods) and downstream (winter floods) from the dam during the 1934–1994 period. This comparison revealed that the principal change observed downstream from the dam translates into a strong increase in the duration (in days) of heavy floods. The average duration of these floods quintupled. This change in duration occurred around the mid‐1960s and thus led to a significant decrease in the magnitude, frequency and variability of heavy floods. It also altered the relationship between the climate indices and these fundamental characteristics (magnitude, frequency and duration). Downstream from the dam, the magnitude and frequency are positively correlated to the Atlantic multidecadal oscillation (AMO), whereas upstream they are negatively correlated to the same index. However, the AMO index is negatively correlated to the duration downstream from the dam, whereas upstream this characteristic is no longer significantly correlated to any climatic index.Two factors have been invoked to explain this change observed downstream from the dam.

The cooling observed since the 1960s at the station located at the dam. However, this cooling was not observed on the scale of the entire watershed. This reduces its plausibility.
The increase in hydroelectric power production in the watershed after nationalization of hydroelectric power in 1962. This increase would be explained by the expansion of the market for hydroelectric power (national and international markets). Before nationalization, the hydroelectric power produced in the watershed was intended only for regional industries.
Copyright © 2010 John Wiley & Sons, Ltd.
Ökobilanzierung von Baustahl
Authors: Kreißig Johannes , Hauke Bernhard , Kuhnhenne Markus 
Published: June 2010

AbstractDie mit der überarbeiteten Bauproduktenverordnung neu hinzu kommende Basisforderung nach nachhaltiger Nutzung der natürlichen Ressourcen muss zukünftig bei der europäisch harmonisierten Vermarktung von Bauprodukten berücksichtigt werden. Bauwerke müssen entsprechend entworfen, errichtet und rückgebaut werden. Weiterhin ist zu gewährleisten, dass das Bauwerk, seine Baustoffe und Teile nach dem Rückbau recycelt werden können, das Bauwerk dauerhaft ist und für das Bauwerk umweltfreundliche Rohstoffe und Sekundärbaustoffe verwendet werden.In diesem normativen Kontext kommt der Ökobilanzierung von Baustoffen eine wachsende Bedeutung zu. Auch für die Nachhaltigkeitsbewertung von Gebäuden, z. B. nach dem DGNB Gütesiegel, sind qualifizierte Umweltdaten der verwendeten Baustoffe eine wichtige Eingangsgröße. Dieser Beitrag beschreibt die Ökobilanzierung von Baustoffen im Allgemeinen und von Baustahl im Speziellen.Eco‐balance of structural steel. With the upcoming Construction Product Requirements (CPR) the new basic requirement of sustainable utilization of natural resources must also be obeyed by the harmonized European market for construction products. Buildings must be designed, constructed and dismantled accordingly. Furthermore it must be assured that the buildings, the materials and members they are made of can be recycled, that the building is durable and that only environmentally sound raw materials and products are employed.Within this normative context eco‐balancing of construction materials has a growing importance. Also for the sustainability assessment of buildings, e. g. according to the DGNB label, qualified eco‐data of the employed construction materials are an important input. This paper describes the eco‐balancing of construction materials in general and of structural steel in particular.
Zuschrift zu: Ungermann, D., Kalameya, J., Brune, B.: Zur Tragfähigkeit von druck‐ und biegebeanspruchten C‐Profilen aus Stahl.
Authors: Hanf Manfred 
Published: June 2010

Abstract[Stahlbau 78 (2009), H. 11, S. 822–831 10.1002/stab.200910098]