bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of recent scaling free methods to predict phenol and phenoxyl radical vibrational properties—Guidelines for more complex models of lignin or protein moieties
Authors: Barsberg Søren 
Published: March 2009

AbstractPhenol and phenoxyl radical are simple models of neutral or oxidized states of important moieties in biomacromolecules such as lignin or proteins. The evaluation of methods to predict their vibrational properties provides a guideline for predictions based on more complex and adequate model compounds. Fundamental frequencies of phenol and phenoxyl radical are predicted from harmonic frequencies νh obtained from B3LYP calculations, and anharmonic corrections Δνanh from HF, MP2 or B3LYP calculations. The complete basis set limit is estimated for νh and IR intensities. Basis set qualities are evaluated for these properties and for Raman activities. Δνanh values compare well between methods, except that MP2 is for the basis sets used unreliable for out‐of‐plane modes. Correlation effects increase Δνanh(HF) values by an average factor ∼1.1, but the correlated values do not improve predicted fundamental frequencies. The B3LYP functional is inadequate for the phenoxyl radical. Errors of approximately 5–6 cm−1 were obtained for the phenol in‐plane low‐frequency modes. For out‐of‐plane modes basis set dependencies are critical to a degree not previously recognized. The predictions appear mainly limited by the method(s) used to calculate νh and Δνanh, and the basis set dependency of Δνanh. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
The δ point interaction two‐center system
Authors: Hogreve H. 
Published: March 2009

AbstractMotivated by the behavior of molecules in strong magnetic fields, we study the quantum system consisting of a particle (electron) interacting with two fixed (nuclear) centers by δ‐type point interactions. Spectral properties and resonances of this model as a function of the internuclear separation are investigated qualitatively and quantitatively. We prove analyticity, monotonicity, and other features, compare them with corresponding attributes of related Coulomb systems, and point out the consequences for molecules. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
The reaction of N2O5 with H3O+: A first‐principles direct molecular dynamics study of acid‐catalyzed reactive uptake of N2O5
Authors: Ishikawa Sascha T. , Nakajima Takahito 
Published: March 2009

AbstractDirect molecular dynamics simulations of N2O5 + H3O+ collision were conducted; (1) to assess the importance of acid‐catalyzed N2O5 decomposition paths expected to play a significant role in the chemistry of stratospheric ozone depletion and (2) for their potential to identify unexpected decomposition paths. A single H3O+‐catalyzed N2O5 decomposition path was observed. Products formed are H2O, NO, HNO3, and complexes of the decomposition products, (H2O)(NO), (H2O)(HNO3), and (HNO3)(NO). All decompositions were barrierless, including complex formations of the products. Reaction exothermicities, which were characterized with a QCISD(T)/6‐311++G(d,p)//MP2/6‐311++G(d,p) model, ranged from 5.9 to 32.0 kcal/mol. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Sequence dependent proton‐transfer reaction in stacked GC pair I: The possibility of proton‐transfer reactions
Authors: Matsui Toru , Sato Takeshi , Shigeta Yasuteru 
Published: March 2009

AbstractWe explored the possibilities of proton‐transfer reactions between guanines (G) and cytosines (C) in stacking two GC pairs by means of density functional methods. There are two combinations of sequences, GC/GC (5′‐dGpG‐3′) and CG/GC (5′‐dCpG‐3′). We found that the simultaneous single proton transfer (SPT) in two base pairs, two independent double proton transfer (DPT), and continuous double SPT reactions strongly depend on the sequence of the DNA, because the SPT reaction occurs in specific sequences including CG/GC and the latter DPTs occur in those including GC/GC. The properties of the DPT products, such as effective charges, are almost the same as the original GC/GC, whereas the effective charges on G and C in the simultaneous SPT product become negative and positive in comparison with those in the original GC/GC. Coulomb attraction caused by the charge separation mainly contributes to the stability of the SPT product. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Accelerating convergence in iterative solution for large‐scale complete active space self‐consistent‐field calculations
Authors: Yanai Takeshi , Kurashige Yuki , Ghosh Debashree , Chan Garnet Kin‐Lic 
Published: March 2009

AbstractAn algorithm that accelerates the convergence of the iterative optimization of the complete active space self‐consistent field (CASSCF) wavefunction so as to find a optimum solution in fewer macroiterations is described. The algorithm is oriented to large‐scale CASSCF problems that are to be solved with a combination of density matrix renormalization group (DMRG) method for the configuration interaction (CI) process. The algorithm is based on the alternating (or two‐step) CASSCF optimization in which the CI and molecular orbital (MO) parameters are optimized separately. Convergence ratio is improved by finding further optimized MOs from a linear extrapolation of the MO sets of the iteration history. The acceleration results in fewer diagonalizations in a total CASSCF calculation to save a considerable computational cost. The convergence performance is examined in a couple of realistic applications on SiC3 and poly(phenyl)carbenes. For poly(phenyl)carbenes, the large‐size CASSCF calculations with CAS(30e,30o) that entails full π valence space as well as sp2 orbital space of carbenes are performed by using the practical implementation of DMRG‐CASSCF in conjunction with the acceleration technique. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Theoretical study of acetonitrile‐exchange reactions on hexasolvated divalent cations in the first transition series elements
Authors: Wasada Hiroaki , Wasada‐Tsutsui Yuko , Hashimoto Tomohiro , Funahashi Shigenobu 
Published: March 2009

AbstractPenta‐, hexa‐, and heptaacetonitrile complexes of divalent cations of the first transition series are studied by ab initio molecular orbital calculations. The factors that determine the structural stability and the reaction mechanism of solvent‐exchange reactions are discussed. All the penta‐ and hexaacetonitrile species are at local minima, whereas the geometrical stability of the heptacoordinated species depends on the 3d electron configurations. The structural stability of heptaacetonitrile species is intermediate between those of hydrogen cyanide complexes and hydrates. Acetonitrile exchange reactions have more dissociative character than hydrogen cyanide exchange reactions because the inductive effect of the methyl group in CH3CN destabilizes the heptacoordinated structures. The successive binding energies show that associative mechanisms are favorable for acetonitrile exchange with earlier members of the first transition series, whereas dissociative mechanisms become favorable for later members. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Accurate torsional potentials for monohalo and fluorohalo keto‐enolate compounds
Authors: Vongachariya Arthit , Tantiwattanakul Sutheera , Parasuk Vudhichai 
Published: March 2009

AbstractAccurate torsional potentials upon two rotatable carbon–carbon bonds for monohalo and fluorohalo keto‐enolate compounds were constructed using CCSD(T)/CBS level of theory. Stable conformers of monohalo and fluorohalo keto‐enolates can be determined from the steric repulsion between moieties around these carbon–carbon bonds. The repulsion between fluorine and halogen atoms is the strongest and stronger than that between oxygen and halogen, followed by that between oxygen and oxygen. The maximum of the torsional potentials corresponds to the conformation where both or one of the two rotatable bonds align perpendicular to the molecular plane, suggesting the strong double bond character between these two carbon–carbon bonds. Thus, the π‐bond conjugation and steric repulsion control the torsional potentials of monohalo and fluorohalo keto‐enolate compounds. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
The NHN+ hydrogen bridge between 4,5‐dihydro‐1H‐imidazole and various amines
Authors: Lankau Timm , Yu Chin‐Hui 
Published: March 2009

AbstractThe B3LYP/D95+(p,p) analysis of the NHN+ bridge between 4,5‐dihydro‐1H‐imidazole and 23 amines covering a proton affinity range from 213 to 257 kcal/mol reveals a continues transition between different types of hydrogen bonding, Van der Waals bond, standard hydrogen bond, double well hydrogen bond, and low barrier hydrogen bond. The mismatch in the proton affinities ΔPA of 9 kcal/mol for an intrinsic low barrier hydrogen bond (LBHB) shows that the chemical environments of the bridge head nitrogen atoms differ significantly and that heteromolecular NHN+ bridges have properties similar to heteronuclear OHN+ LBHBs. The analysis further showed that the properties of NHN+ LBHBs are similar to those observed in other hydrogen bonds and that the reliable classification of hydrogen bonds requires the careful analysis of all available data. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Fast liquid chromatography/multiple‐stage mass spectrometry of coccidiostats
Authors: Martínez‐Villalba Anna , Moyano Encarnación , Galceran Maria T. 
Published: March 2009

AbstractDrugs that are used as medicines and also as growth promoters in veterinary care are considered as emerging environmental contaminants and in recent years concern about their potential risk to ecosystems and human health has risen. In this paper we used a method based on liquid chromatography/electrospray tandem mass spectrometry to analyze eight coccidiostatic compounds: diclazuril, dinitrocarbanilide (the main metabolite of nicarbazin), robenidine, lasalocid, monensin, salinomycin, maduramicin and nasarin. Multiple‐stage mass spectrometry (MSn) based on the precursor ions [M+Na]+ (polyether ionophores), [M+H]+ (robenidine) and [M–H]− (diclazuril and dinitrocarbanilide) was used to study the fragmentation of these compounds. MSn data and genealogical relationships were used to propose a tentative assignment of the different fragment ions. Loss of water, decarboxylations, ketone β‐cleavages and rearrangement of cyclic ethers and amide groups were some of the fragmentations observed for these compounds. Liquid chromatography with a sub‐2 µm particle size column was coupled to tandem mass spectrometry (LC/MS/MS) allowing the separation of these compounds in less than 7 min. Method detection limits ranging from 11 to 71 ng L−1 and run‐to‐run values in terms of relative standard deviation (RSD) (up to 12%) were obtained. Copyright © 2009 John Wiley & Sons, Ltd.
In situ chemical oxidation of residual LNAPL and dissolved‐phase fuel hydrocarbons and chlorinated alkenes in groundwater using activated persulfate
Authors: Siegal Joan , Rees Assaf A. , Eggers Karl W. , Hobbs Rebecca L. 
Published: March 2009

AbstractA treatablity study (TS) was conducted to evaluate the efficacy of in situ chemical oxidation (ISCO) using activated persulfate, alone and in combination with air sparging (AS), for treating a source area contaminated with residual light nonaqueous‐phase liquid (LNAPL), dissolved‐phase fuel hydrocarbons (HCs), and dissolved‐phase chlorinated alkenes at Edwards Air Force Base (AFB), California. The TS was implemented in two phases. Phase I included injecting a solution of sodium persulfate and sodium hydroxide (NaOH) into groundwater via an existing well where residual LNAPL and dissolved‐phase contaminants were present. Because the results of Phase I indicated a limited distribution of the activated persulfate, Phase II was performed to assess whether AS could enhance the distribution of the sodium persulfate. Each phase was followed by groundwater monitoring and sampling at the injection well and at three monitoring wells, located 20 to 44 feet from the injection well. Results from Phases I and II of the TS indicated that (1) alkaline‐activated persulfate was effective in promoting the dissolution of LNAPL and the degradation of dissolved‐phase contaminants, but only at the injection well; (2) the addition of AS was effective in enhancing the radius of persulfate distribution from less than 20 feet to greater than 44 feet, and (3) persulfate alone (i.e., not in an activated state) was effective in reducing the concentrations of dissolved‐phase fuel HC and chlorinated alkenes. © 2009 Wiley Periodicals, Inc.
Successful unsaturated zone treatment of PCE with sodium permanganate
Authors: Hesemann John R. , Hildebrandt Martha 
Published: March 2009

AbstractIn situ chemical oxidation (ISCO) with permanganate has been widely used for soil and groundwater treatment in the saturated zone. Due to the challenges associated with achieving effective distribution and retention in the unsaturated zone, there is a great interest in developing alternative injection technologies that increase the success of vadose‐zone treatment.The subject site is an active dry cleaner located in Topeka, Kansas. A relatively small area of residual contamination adjacent to the active facility building has been identified as the source of a large sitewide groundwater contamination plume with off‐site receptors. The Kansas Department of Health and Environment (KDHE) currently manages site remedial efforts and chose to pilot‐test ISCO with permanganate for the reduction of perchloroethene (PCE) soil concentrations within the source area. KDHE subsequently contracted Burns & McDonnell to design and implement an ISCO pilot test.A treatability study was performed by Carus Corporation to determine permanganate‐soil‐oxidant‐demand (PSOD) and the required oxidant dosing for the site. The pilot‐test design included an ISCO injection approach that consisted of injecting aqueous sodium permanganate using direct‐push technology with a sealed borehole.During the pilot test, approximately 12,500 pounds of sodium permanganate were injected at a concentration of approximately 3 percent (by weight) using the methods described above. Confirmation soil sampling conducted after the injection event indicated PCE reductions ranging from approximately 79 to more than 99 percent. A follow‐up treatment, consisting of the injection of an additional 6,200 pounds of sodium permanganate, was implemented to address residual soil impacts remaining in the soil source zone. Confirmation soil sampling conducted after the treatment indicated a PCE reduction of greater than 90 percent at the most heavily impacted sample location and additional reductions in four of the six samples collected. © 2009 Wiley Periodicals, Inc.
Managing environmental problems during transitions: The department of energy as a case study
Authors: Burger Joanna , Gochfeld Michael , Powers Charles W. , Kosson David , Greenberg Michael , Toffler Barbara Ley 
Published: March 2009

AbstractMany federal, state, and private agencies deal with long‐term environmental problems within a transition framework where political administrations, funds, regulators, regulatory requirements, environmental conditions, and tribal and stakeholder concerns change. In this article, we examine the types of transitions, as well as important stabilities, that agencies face, the interactions with stakeholders that are vulnerable to disruption or failure, and some of the problems that develop as a result of these conditions, using the U.S. Department of Energy (US DOE's) Office of Environmental Management (EM) as a case study. Transitions, or instabilities, include changes in administrations at the federal, state, and local level; public perceptions and concerns; political climate; available funds; environmental conditions (e.g., global climate change, global contaminant transport, local and regional contamination); international and national business conditions; and site conditions (physical, chemical, biological). Governmental agencies operate under several different kinds of uncertainties, including scientific, fiscal‐year economic, technological, and societal. Not all information can be known, and the outcomes from scientific issues or technologies cannot always be predicted. The authors believe that transitions from one set of conditions to another can be more effectively integrated with the long‐term stability of environmental laws and regulations, and with the stability of the treaty rights and concerns of tribal nations, as well as the shorter‐term stability of career personnel and established programs. A sense of stability for government agencies allowing maintenance of ongoing environmental management programs can also be achieved through processes and programs, such as establishing long‐term contracts (for remediation or restoration work), schedule and scope documents, future land‐use documents, National Environmental Research Parks (which obligate lands to study and conservation), and other programs that set the direction of work and activities for many years. Further, two other factors are essential for success within any agency facing transitions: (1) expectations should be both forward‐looking and realistic, and (2) there must be flexibility in both programs and processes. The authors conclude that several features are essential to addressing some of the problems created by transitions, including information, integration, iteration, interaction, and inclusion. © 2009 Wiley Periodicals, Inc.
Use of Fenton's Reagent as a Disinfectant
Authors: Selvakumar Ariamalar , Tuccillo Mary Ellen , Muthukrishnan Swarna , Ray Asim B. 
Published: March 2009

AbstractSeveral compositions of Fenton's Reagent and hydrogen peroxide alone were used to disinfect combined sewage samples from a wastewater treatment facility. The presettled samples contained suspended solids (SS) and dissolved organic carbon (DOC) at concentrations of 28 and 290 mg/L, respectively. Disinfection with Fenton's Reagent was carried out at a pH between 5.90 and 6.0 and at a temperature of 25°C. All disinfected samples contained residual oxidants. Under all reaction conditions studied, complete inactivation of E. coli was achieved within one minute of the addition of Fenton's Reagent. Disinfection with hydrogen peroxide alone under similar conditions is incomplete even under much longer contact times. © 2009 Wiley Periodicals, Inc.
Transmission line maintenance robots capable of crossing obstacles: State‐of‐the‐art review and challenges ahead
Authors: Toussaint Kristopher , Pouliot Nicolas , Montambault Serge 
Published: March 2009

AbstractPower line inspection and maintenance already benefit from developments in mobile robotics. This paper presents a comprehensive review of the state of the art. It focuses on mobile robots designed to cross obstacles found on a typical transmission line while using the conductor as support for traveling. Promising areas of research and development as well as challenges that remain to be solved are discussed with a view to developing fully autonomous technologies. Maintenance tasks, including inspection and repairs, are identified as high‐value applications in transmission live‐line work. Conclusions are drawn from experience, and the future of mobile robotics applied to transmission line maintenance is discussed. © 2009 Wiley Periodicals, Inc.
Changes in biomass and structure after a fire in Spartina densiflora Brong marshes on the floodplain of the Paraná River, Argentina
Authors: Vicari Ricardo , Fischer Sylvia , Madanes Nora , Bonaventura Stella M. 
Published: March 2009

AbstractWe examined the responses of a Spartina densiflora (Poaceae) marsh to an accidental summer fire taking place in the Otamendi Natural Reserve (Argentina). Green, standing dead, reproductive and litter fractions of S. densiflora, as well as forbs biomass were determined before and after burning using randomly selected quadrates. Fire reduced most of the aboveground biomass of the green, standing dead and litter fractions of S. densiflora. Green biomass attained higher values before the fire as compared to those from the first year after burning during the spring, while the second year spring attained intermediate values. The standing dead material represented the main fraction of S. densiflora biomass in the pre‐fire period, and after burning, this fraction reappeared in autumn, 4 months after the fire. The litter showed zero values throughout the first 16 months after the fire, and reappeared at end of the second winter. The flower biomass was exclusively recorded on late summer and showed relatively low values. Seedling recruitment of S. densiflora was not observed throughout the study period. Forbs biomass showed large fluctuations both before and after fire and highest forbs biomass values were observed during the spring before fire, and at end of summer 1 year after the fire. Although the results of the present study showed a tendency towards the original structure, most of the biomass fractions did not reach values similar to those before the fire after 2 years of post‐fire growing, suggesting that a longer recovering time is expected. Copyright © 2009 John Wiley & Sons, Ltd.
Entrepreneur behaviors, opportunity recognition, and the origins of innovative ventures
Authors: Dyer Jeffrey H. , Gregersen Hal B , Christensen Clayton 
Published: March 2009

AbstractThis study traces the origins of innovative strategies by examining the attributes of ‘innovative entrepreneurs.’ In an inductive grounded theory study of innovative entrepreneurs, we develop a theory that innovative entrepreneurs differ from executives on four behavioral patterns through which they acquire information: (1) questioning; (2) observing; (3) experimenting; and (4) idea networking. We develop operational measures of each of these behaviors and find significant differences between innovative entrepreneurs and executives in a large sample survey of 72 successful and unsuccessful innovative entrepreneurs and 310 executives. Drawing on network theory, we develop a theory of entrepreneurial opportunity recognition that explains why these behaviors increase the probability of generating an idea for an innovative venture. We contend that one's ability to generate novel ideas for innovative new businesses is a function of one's behaviors that trigger cognitive processes to produce novel business ideas. We also posit that innovative entrepreneurs are less susceptible to the status quo bias and engage in these information‐seeking behaviors with a motivation to change the status quo. Copyright © 2009 Strategic Management Society.
Opportunities as attributions: Categorizing strategic issues from an attributional perspective
Authors: Gartner William B. , Shaver Kelly G. , Liao Jianwen (Jon) 
Published: March 2009

AbstractThis study explores the label ‘opportunity’ in the strategic issue literature as a point of departure for offering an attributional framework for categorizing opportunities entrepreneurs offer as they undertake efforts to start businesses. The strategic issue literature broadly labels opportunities as being positive and controllable and involving potential gain. We demonstrate that this is similar to an attribution theory approach. In preparing this article, the authors analyzed open‐ended questions from the Panel Study of Entrepreneurial Dynamics (PSED). Entrepreneurs were more likely to offer attributions about their opportunities that can be categorized as dependent on their abilities (internal and stable attributions) and efforts (internal and variable attributions). Copyright © 2009 Strategic Management Society.