bluuebunny/crossref_metadata_2025_split huggingface dataset:
Charge Distribution in 3′‐Deoxythymidine‐Fullerene: Mass Spectrometry, Laser Excitation, and Computational Studies
Authors: Greisch J.‐F. , Weinkauf R. , DePauw E. , Kryachko E. S. , Remacle F. 
Published: June 2008

AbstractElectrospray ionization of the donor–spacer–acceptor model system 3′‐imino[60]fulleryl‐3′‐deoxythymidine molecule (FdT) produces deprotonated negatively charged species (dFdT). In this paper, we investigate where the negative charge is localized and whether its location can be manipulated. The fragmentation of dFdT is studied experimentally by mass spectrometry using both collisional and photoactivation. Besides fragmentation, photoexcitation of anions stored in an ion trap leads to electron photodetachment. The competition between the two channels is studied as a function of the excitation wavelength. Starting from the neutral parents, two families of dFdT molecules are computationally identified. Deprotonation takes place on the 3′‐deoxythymidine (dT) subunit, either on the thymine at N3 or on the deoxyribose residue at O5′. Deprotonation in N3 leads to negatively charged molecules with an extended geometry and the excess charge largely localized on the dT The O5′‐deprotonation leads to lower‐energy folded conformers stabilized by an additional bond (C–O or C–H) with the nearby C60–N acceptor part, and the negative charge is mostly localized on the fullerene. The calculated electron detachment energies are higher for the extended N3dFdT conformers than for the O5′dFdT ones. Multiphoton photodetachment experiments at 1064 nm indicate the negative charge to be on the C60 unit. No indication for a photoinduced charge transfer was found. In MS beside the C60 anion a C60NH2– fragment is observed, which implies a double intramolecular H transfer. The computed energy of the corresponding dFdT, stabilized by two H–C60 bonds, is intermediate between N3 and O5′ deprotonated molecules.
Chemisorption of Nitrogen Monoxide on Size‐Selected Cobalt Cluster Ions
Authors: Hanmura Tetsu , Ichihashi Masahiko , Kondow Tamotsu 
Published: June 2008

AbstractCollisional reactions of NO with Con+ (n = 2–10) were studied by measuring the absolute cross sections for creating the product ions in a beam‐gas geometry at different collision energies and internal temperatures of Con+. The dominant reaction is chemisorption of NO on Con+ (formation of ConNO+ and Con–1NO+). As n increases, the chemisorption cross section starts to rise sharply at n = 4 and soon reaches the highest possible value, which is the Langevin cross section. The chemisorption cross section practically does not change with the internal temperature, while the branching fraction for the production of ConNO+ with respect to the sum of ConNO+ and Con–1NO+ decreases with the internal temperature in the size range of n = 6–10. A statistical model based on the RRK theory explains the dependences of the chemisorption cross section and the branching fraction on the size (n), the collision energy, and the internal temperature. The energies of the NO chemisorption derived from the dependences of the chemisorption cross section and the branching fraction on the collision energy and the internal temperature show that (1) the NO chemisorption is dissociative for n ≥ 4 and (2) more than one isomer is involved in the chemisorption of NO on Co9+.
Competition between Fission and Intra‐Cluster Fusion in Highly Excited Fullerene Clusters
Authors: Hansen Klavs , Kjellberg Mikael , Bulgakov Alexander V. , Campbell Eleanor E. B 
Published: June 2008

AbstractThe occurrence of intra‐cluster fusion of fullerene molecules inside van der Waals bound fullerene clusters can be observed following femtosecond laser excitation. We show that the fusion reaction competes with the fission of multiply charged clusters. Energetic barriers to the reaction of at least 85 eV have to be overcome, similar to the energetic barriers to molecular fusion observed in fullerene ion‐neutral fullerene collision experiments.
Quantum Entanglement and Electron Correlation in Molecular Systems
Authors: Wang Hefeng , Kais Sabre 
Published: June 2008

AbstractWe study the relation between quantum entanglement and electron correlation in quantum chemistry calculations. We prove that the Hartree–Fock (HF) wave function does not violate Bell's inequality, and thus is not entangled, whereas the configuration interaction (CI) wave function is entangled since it violates Bell's inequality. Entanglement is related to electron correlation and might be used as an alternative measure of the electron correlation in quantum chemistry calculations. As an example we show the calculations of entanglement for the H2 molecule and how it correlates with the traditional electron correlation, which is the difference between the exact and the HF energies.
Quantum Motion Effects in Atom Interferometry
Authors: Seidel Dirk , Muga J. Gonzalo 
Published: June 2008

AbstractWe study the Ramsey interference pattern of ultracold atoms crossing two electromagnetic fields, taking into account quantum motion effects. It is shown that quantum reflection and transmission at the fields lead to a modification of the standard fringes. The implications on present frequency standards are discussed. For weak coupling, the difference between the exact quantum result and the semiclassical result is small but results in a central peak shift that may become important for future accuracies of atomic clocks. In the strong coupling regime, a resonance structure with respect to the detuning is observed and the Ramsey setup acts as a matter‐wave Fabry‐Perot device. Our results question the advantage of using increasingly lower velocities in frequency standards because the peak shift and the resonance positions depend sensitively on very minor variations of the atomic velocity and are difficult to control.
Intracavity Laser Absorption Spectroscopy for flame diagnostics
Authors: Rahinov Igor , Goldman Anatoly , Cheskis Sergey 
Published: June 2008

AbstractIntracavity Laser Absorption Spectroscopy (ICLAS) is one of the most sensitive techniques in absorption spectroscopy. Application of this technique to combustion diagnostics offers many important advantages. Since ICLAS is an absorption‐based method, it is not limited by the quenching and predissociation effects that compromise the sensitivity of Laser Induced Fluorescence (LIF), one of the most sensitive and widespread techniques applied in combustion diagnostics. For that reason, radicals that are subject to strong collisional quenching or predissociation, such as 1CH2 and HCO, can be measured by ICLAS with sensitivity much greater than that of LIF. For the same reason, ICLAS also possesses better sensitivity for NH and HNO. The present paper overviews the ICLAS measurements performed during the last decade in our laboratory and also presents recent results: first‐time detection of the HSO radical in flames by ICLAS and application of Fiber Laser Intracavity Absorption Spectroscopy (FLICAS) based on Er‐doped fiber laser for in‐situ detection of ammonia and hydrogen cyanide in a low‐pressure methane/air flame doped with a small amount of ammonia. Avenues for future research are discussed.
Transparent triethylamine‐containing MALDI matrices
Authors: Rubakhin Stanislav S. , Sweedler Jonathan V. 
Published: June 2008

AbstractIn matrix‐assisted laser desorption/ionization (MALDI) mass spectrometric (MS) imaging of biological tissues, an organic matrix is deposited onto a sample and co‐crystallized with the peptides and proteins that are extracted from the tissue. Thus, analytes are incorporated into matrix crystals, making them accessible to the matrix‐assisted desorption/ionization process. However, crystal dimensions can limit the spatial resolution of these imaging experiments and hinder observation of small features in the tissue. The addition of differing amounts of triethylamine (TEA) to solutions of common MALDI matrices—α‐cyano‐4‐hydroxycinnamic acid (CHCA), 2,5‐dihydroxybenzoic acid, and sinapinic acid—results in the formation of liquid matrices that may alleviate these problems. Liquid matrices form optically transparent, viscous films that do not crystallize, even when kept open to air for several days at room temperature or placed in the vacuum of the mass spectrometer. These matrices allow peptides to be characterized using MALDI MS down to the femtomole level. Although signal intensity is reduced in liquid matrices as compared to standard crystalline matrices, a phenomenon especially evident for higher molecular mass analytes, peptides are still detected even when TEA comprises 2/3 (v/v) of the MALDI matrix mixture. Transparent matrices demonstrate excellent repeatability and sample stability. Post‐source decay sequencing of peptides with a CHCA/TEA matrix produces intense peptide fragment signals in the low molecular mass region, and rat pituitary blots yield high‐quality spectra using these mixtures. Overall, TEA‐based transparent MALDI matrices are promising for coupling MALDI MS and light microscopy.
Collisional energy transfer in polyatomic molecules in the gas phase
Authors: Bernshtein Victor , Oref Izhack 
Published: June 2008

AbstractThis paper is an attempt to present an overall view of energy transfer between excited polyatomic molecules and polyatomic and monatomic bath, based on results obtained by classical trajectory calculations. It is not a general review of the subject but a summary based on work done by us in the last few years. We report average energies transferred in a collision and collisional energy transfer probability density functions for various collision partners as a function of various system parameters: temperature, vibrational and rotational energies of the hot and cold molecule, and relative translational energies. Various mechanisms for energy transfer are proposed, their dependence on the system parameters is explored, and the relevance of empirical numerical models to computational results is discussed.
Long‐range hydrodynamic response of particulate liquids and liquid‐laden solids
Authors: Diamant Haim 
Published: June 2008

AbstractIn viscous particulate liquids, such as suspensions and polymer solutions, the large‐distance steady‐state flow due to a local disturbance is commonly described in terms of hydrodynamic screening—beyond a correlation length ξ the response drops from that of the pure solvent, characterized by its viscosity η0, to that of the macroscopic liquid with viscosity η > η0For cases where η >> η0we show, based on general conservation arguments, that this screening picture, while being asymptotically correct, should be refined in an essential way. The crossover between the microscopic and macroscopic behaviors occurs gradually over a wide range of distances, ξ <r< (η / η0)1/2ξ In liquid‐laden solids, such as colloidal glasses, gels, and liquid‐filled porous media, where η → ∞, this intermediate behavior takes over the entire large‐distance response. The intermediate flow field, arising from the effect of mass displacement rather than momentum diffusion, has several unique characteristics: (i) It has a dipolar shape with l/r3spatial decay, negative transverse components, and vanishing angular average. (ii) Its amplitude depends on the liquid properties through η0and ξ alone; thus, in cases where ξ is fixed by geometry (e.g., for particulate liquids tightly confined in solid matrices), the large‐distance response is independent of particle concentration. (iii) The intermediate field builds up non‐diffusively, with a distance‐independent relaxation rate, making it dominant at large distances before steady state has been reached. We demonstrate these general properties in three model systems.
Extreme multielectron ionization of elemental clusters in ultraintense laser fields
Authors: Heidenreich Andreas , Last Isidore , Jortner Joshua 
Published: June 2008

AbstractIn this paper we present computational and theoretical studies of extreme multielectron ionization in Xen clusters (n = 55‐2171, initial cluster radii R0 = 8.7‐31.0 Å) driven by ultraintense Gaussian infrared laser fields (peak intensity IM = 1015‐1020 W cm−2, temporal pulse length τ = 10‐100 fs, and frequency v = 0.35fs−1). The microscopic approach, which rests on three sequential‐parallel processes of inner ionization, nanoplasma formation, and outer ionization, properly describes the high ionization levels (with the formation of {Xeq+}n with q = 5‐36), the inner/outer cluster ionization mechanisms, and the nanoplasma response. The cluster size and laser intensity dependence of the inner ionization levels are determined by a complex superposition of laser‐induced barrier suppression ionization (BSI), with the contributions of the inner field BSI manifesting ignition enhancement and screening retardation effects, together with electron impact ionization. The positively charged nanoplasma produced by inner ionization reveals intensity‐dependent spatial inhomogeneity and spatial anisotropy, and can be either persistent (at lower intensities) or transient (at higher intensities). The nanoplasma is depleted by outer ionization that was semiquantitatively described by the cluster barrier suppression electrostatic model, which accounts for the cluster size, laser intensity, and pulse length dependence of the outer ionization yield.
Enhanced kinetics of solid-phase microextraction and biodegradation of polycyclic aromatic hydrocarbons in the presence of dissolved organic matter
Authors: Haftka Joris J.H , Parsons John R , Govers Harrie A.J , Ortega-Calvo José-Julio 
Published: June 2008

Abstract
The uptake kinetics of fluorene, phenanthrene, fluoranthene, pyrene, and benzo[e]pyrene by solid-phase microextraction fibers was studied in the presence of dissolved organic matter (DOM) obtained from sediment pore water and resulted in increased fiber absorption and desorption rate coefficients. Compared to the control without DOM, these rate coefficients were increased at a DOM concentration of 36.62 mg/L by a factor of 1.27 to 2.21 and 1.31 to 2.10 for fluorene and benzo[e]pyrene, respectively. The calculated values for the fiber absorption and desorption rate coefficients show that diffusion through an unstirred boundary layer (UBL) surrounding the fiber probably forms the rate-limiting step of the process. The mineralization of aqueous-phase phenanthrene and pyrene by a representative polycyclic aromatic hydrocarbon (PAH)-degrading bacterium (Mycobacterium gilvum VM552) also was found to be enhanced by DOM. The initial degradation rates of phenanthrene (9.03 μg/L) and pyrene (1.96 μg/L) were significantly higher compared to the control values and were enhanced by a factor of 1.32 and 1.26 at a DOM concentration of 43.14 and 42.15 mg/L, respectively. We suggest that such an enhancement results from the combination of faster uptake kinetics of the water-dissolved compounds in the UBL surrounding microbial cells and direct access of the bacteria to DOM-associated PAHs. These enhanced kinetic effects of DOM may have strong implications in sediment processes like desorption, nonequilibrium exposure, and biodegradation.
Conformance While Fracturing Tight Gas Formations
Authors: Dalrymple Dwyann , Eoff Larry , Everett Don 
Published: June 2008

Abstract
The industry is continuing to expand production from reservoirs that had previously been passed over because of less than desirable properties such as low porosity, permeability, high water saturations, and/or being in close proximity to water. Because of this, water production after a hydraulic fracturing operation is an even greater concern and can make stimulation of these intervals an uneconomical venture.
This paper discusses how water production has been significantly reduced using a new conformance-while-fracturing (CWF) method that incorporates a hydrophobically modified water-soluble polymer (HMWSP) to function as a relative permeability modifier (RPM) incorporated into the fracturing treatment design.
The purpose of the HMWSP is to reduce the effective permeability to the flow of water without significant changes to the flow of the hydrocarbon. A low gel loading borate crosslinking fluid is used to fracture stimulate the wells.
The increase in water production with the CWF method is typically less than 50% that of offset wells that had been fracture stimulated with conventional methods. Additionally, the total production of the wells stimulated using the CWF method usually resulted in lower water-gas ratios. This paper describes the properties of the HMWSP, general CWF job-design considerations, field applications, and post-fracturing result comparisons of the CWF method with offset wells.
A holistic approach and object-oriented framework for eco-hydraulic simulation in coastal engineering
Authors: Milbradt P. , Schonert T. 
Published: June 2008

The consideration of biological processes in hydro- and morphodynamic models is an important challenge for numerical simulation in coastal engineering. Eco-hydraulic aspects will play a major role in engineering tools and planning processes for the design of coastal works. Vegetation greatly affects the hydro- and morphodynamic models in coastal zones. Most hydrodynamic numerical models do not consider influences by ecological factors.
This paper focuses on the presentation of an object-oriented holistic framework for eco-hydraulic simulation. The numerical approximation is performed by a stabilized finite element method for hydro- and morphodynamic processes, to solve the related partial differential equations, and by a cell-oriented model for the simulation of ecological processes, which is based on a fuzzy rule system. The fundamental differences between these model paradigms require special transfer and coupling methods. Case studies on seagrass prediction in the North Sea around the island of Sylt show the main effects and influences on changed hydro- and morphodynamic processes and demonstrate the applicability of the coupled finite element fuzzy cell-based approach in eco-hydraulic modeling.
Near-infrared spectroscopy extended with indocyanine green dye dilution for cerebral blood flow measurement: Median values in healthy volunteers
Authors: Mudra R. , Muroi C. , Niederer P. , Keller E. 
Published: June 2008

AbstractThe cerebral blood flow (CBF) is an important vital parameter in neurointensive care. Currently, there is no non-invasive method for its measurement that can easily be applied at the bedside. A new tool to determine CBF is based on near-infrared spectroscopy (NIRS) applied together with indocyanine green (ICG) dye dilution. From a bilateral measurement on selected regions on the head of infrared (IR) absorption at various wavelengths during the dilution maneuver, the vascular perfusion characteristics of the two brain hemispheres can be determined in terms of mean transit time (mtt) of ICG, cerebral blood volume (CBV) and CBF.So far, on nine healthy volunteers, NIRS ICG dye dilution bihemispheric measurements were performed, which yielded to mtt given as median (range) of 9.3 s (5.1–16.3 s), CBV of 3.5 ml/100 g (1.7–4.1 ml/100 g), and CBF of 18.2 ml/(100 g×min) [11.1–48.6 ml/(100 g×min)]. Additionally, the blood flow index (BFI) was calculated with BFI= 13.8 mg/(100 g×s) [6.6–15.2 mg/(100 g×s)]. The Spearman rank correlation coefficient between CBF and BFI was RS = 0.76. However, as the Bland & Altman plot between CBFNIRS and the CBFBFI documents, the limits of agreement are rather wide (21.9±6.7). Under physiological conditions in healthy volunteers, no differences could be detected between the hemispheres.
Research on preliminary concept of ship intended for mining poly-metallic concretions from sea bed
Authors: Bortnowska Monika 
Published: June 2008

Research on preliminary concept of ship intended for mining poly-metallic concretions from sea bed
Necessity to design and build a ship for winning Fe-Mn concretions from sea bed, and put it into operation, results mainly from decreasing land resources of mineral rough materials and increasing prices of metals. Main dimensions and parameters of such mining ship were determined by elaborating its main design assumptions and making use of suitable data on drilling ships considered similar from the point of view of attributed functions and spatial arrangement. In this paper a design study on preliminary concept of dimensions and spatial arrangement of a ship for winning poly-metallic concretions from sea bed, is presented. The study has been aimed at elaboration of an appropriate mathematical model to be applied for optimization of ship's winning system.
Research on a control system based on stepping motor for ship's controllable pitch propellers
Authors: Dymarski Czesław 
Published: June 2008

Research on a control system based on stepping motor for ship's controllable pitch propellers
This paper presents description of a laboratory stand for testing servo-mechanisms of ship low-power CP propellers, as well as a remote control system for such propellers, based on electric stepping motor. Also, are presented results of the first series of tests of the control system, carried out on non-loaded CP propeller by applying stepped values of propeller pitch at two values of rotational speed of the stepping motor.
Linear Congruence Relation and Complete Residue Systems
Authors: Liang Xiquan , Yan Li , Zhao Junjie 
Published: June 2008

Linear Congruence Relation and Complete Residue Systems
In this paper, we defined the congruence relation and proved its fundamental properties on the base of some useful theorems. Then we proved the existence of solution and the number of incongruent solution to a linear congruence and the linear congruent equation class, in particular, we proved the Chinese Remainder Theorem. Finally, we defined the complete residue system and proved its fundamental properties.
Principles of Creation and Reconstruction of Dot-Matrix Holograms
Authors: Bulanovs A. , Gerbreders V. , Paškevičs V. 
Published: June 2008

Principles of Creation and Reconstruction of Dot-Matrix HologramsA method for calculation of dot-matrix holograms is presented, whose distinction from other methods is simplicity of the formulas for the parameters of each pixel element in a hologram. At the Innovation Spectroscopy Center of DU a device for recording dot-matrix holograms has been designed, with a program using the pro-posed method for their calculation. Holograms 50x50 mm in size well corresponding to the initial graphic design were obtained.
Cosmic Ray Nucleonic Intensity in Low-Amplitude Days During the Passage of High-Speed Solar Wind Streams
Authors: Agarwal Rekha , Mishra Rajesh , Tiwari Sharad 
Published: June 2008

Cosmic Ray Nucleonic Intensity in Low-Amplitude Days During the Passage of High-Speed Solar Wind StreamsOne of the most striking features of solar wind is its organization into high- and low- speed streams. It is now well established that the passage over the Earth of high-speed solar wind streams leads to geomagnetic disturbances. The high-speed plasma streams are thus a key element in the complex chain of events that link geomagnetic activity to the solar activity and are therefore of great interest to the solar terrestrial physics. Two types of high-speed solar wind streams - coronal-hole-associated (or corotating) and flare-generated - were studied based on magnetic field and solar wind plasma parameters. In the work, the dependence was obtained for cosmic ray (CR) depressions due to high-speed solar wind streams during low-amplitude days. The CR nucleonic intensity data were subjected to the superposed epoch analysis with respect to the start time of high-speed solar wind streams. It was found that streams of both types produce significant deviations in the CR intensity during low-amplitude anisotropic wave train events. At the onset of such streams the CR intensity reaches its minimum during low-amplitude events and then increases statistically.