bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Product Introduction: Timing, Design, and Pricing
Authors: Klastorin Ted , Tsai Weiyu 
Published: November 2004

In this paper, we consider the case when two profit-maximizing firms enter a new market with a competing product that has a finite (and known) life cycle. Both firms make design decisions simultaneously without information about the other firm's decisions. The order of entry is a function of the two firms' product design levels and design capabilities. The first firm entering the market sets a monopoly price for its product and enjoys a monopoly situation until the second firm enters the market. When the second firm enters the market, both firms simultaneously set (or reset) their product prices knowing the design of both products at that time (and we assume those prices are fixed for the remainder of the product's life). We develop a game-theoretic model that represents the new product introduction process and show that a subgame-perfect Nash equilibrium occurs under certain conditions defined by the expected product life span, product cost, development time, and customer preferences. Our model shows that product differentiation always arises at equilibrium due to the joint effects of resource utilization, price competition, and product life cycle. A critical parameter for our model is a product-specific index B that we define; we show how it can be easily calculated from existing data. We then use a numerical example to illustrate managerial implications for a new product development process when the product life span is finite. We show that the strategy of time-based competition is the natural result of firms' improving development capability, reducing product cost, and increasing customer preference. In other words, it is not wise for profit-maximizing firms to arbitrarily shorten product life cycle for the sake of competition, because all firms are worse off. Our results also indicate that the first entrant into the market does not necessarily earn the greatest profit, and that a firm with low-cost advantage or fast design capability might not choose to come to market first to maximize its profit in the product life cycle.
Study of Jet‐Cooled Bis(η6‐Benzene)Chromium by Multiphoton Zero Kinetic Energy—Mass‐Analyzed Threshold Ionization Spectroscopy
Authors: Ketkov Sergey Yu. , Selzle Heinrich L. , Schlag Edward W. 
Published: November 2004

AbstractZero kinetic energy‐mass‐analyzed threshold ionization (ZEKE‐MATI) spectra of jet‐cooled (η6‐C6H6)2Cr have been obtained for the first time with use of the 3dz2 → R4px,y Rydberg transition as the initial step of the electronic excitation. The ionization potential of (η6‐C6H6)2Cr determined on the basis of the ZEKE‐MATI experiment is 44087 ± 3 cm−1 (5.4661 ± 0.0004 eV). The binding energy of the R4px,y electron is 17333 ± 3 cm−1. The frequencies of the symmetric metal‐ring stretching vibration and CH umbrella vibration in the gas‐phase ground‐state molecular cation (η6‐C6H6)2Cr+ are 262 ± 5 and 788 ± 4 cm−1, respectively.
Conical Intersections: Relaxation, Dephasing, and Dynamics in a Simple Model
Authors: Katz Gil , Kosloff Ronnie , Ratner Mark A. 
Published: November 2004

AbstractConical intersections occur on potential energy surfaces of many medium‐sized and larger molecules. Their investigation, which has been ongoing for more than six decades, shows that vibronic coupling and relaxation behaviors at conical intersections can become quite complex and show large quantum effects. We present calculations of dynamical behavior in very simple (two‐dimensional, degenerate, non‐displaced) conical intersection models. The focus is placed on the effects of bath interactions on conical behavior—that is, the extent to which electronic dephasing, nuclear relaxation, and electronic relaxation affect the initially excited wave packet evolving on conical intersection surface. The calculations are carried through using a density matrix picture, with a Lindblad semi‐group formalism to characterize relaxation. We observe large quantum effects that act particularly on true conical structures (anti‐symmetric with respect to the mixing coordinate), as opposed to comparable‐strength interactions without this symmetry. Significant changes in excited‐state population decay, and even larger and more striking changes in the (observable) bleach recovery signal, are found.
Ultrafast Charge Separation Due to Excited State Symmetry Breaking in Dimers of Push‐Pull Perylenes
Authors: Fuller Michael J. , Gusev Alexey V. , Wasielewski Michael R. 
Published: November 2004

AbstractPhotoexcitation of chromophoric dimers constrained to a symmetric π‐stacked geometry by their molecular structure usually produce excimers independent of solvent polarity, while dimers with edge‐to‐edge perpendicular π systems undergo excited‐state symmetry breaking in highly polar solvents leading to intradimer charge separation. We present direct evidence for symmetry breaking in the lowest excited singlet state of a symmetric cofacial dimer of 9‐(N‐pyrrolidinyl)‐1,6‐bis(3,5‐di‐tert‐butylphenoxy)perylene‐3,4‐dicarboximide (5PMI) in the low‐polarity solvent toluene to produce a radical ion pair quantitatively. This dimer, cof‐5PMI2, was synthesized by attaching two 5PMI chromophores via imide groups to a xanthene spacer. For comparison, a linear symmetric dimer, lin‐5PMI2, was prepared in which the 5PMI chromophores are linked end‐to‐end via a N‐N single bond between their imides. The edge‐to‐edge π systems of the 5PMI chromophores within lin‐5PMI2 are perpendicular to one another. Ground‐state absorption spectra of both 5PMI dimers show exciton coupling, which is consistent with the orientation of the 5PMI chromophores relative to one another. Ultrafast transient absorption spectroscopy following excitation of the dimers with 400‐nm, 80‐fs laser pulses shows that quantitative intradimer electron transfer occurs in cof‐5PMI2 in toluene with τ = 0.9 ps, followed by charge recombination to ground state with τ = 780 ps. Similar measurements on lin‐5PMI2 reveal that photoinduced electron transfer does not occur in toluene, but occurs in more polar solvents such as 2‐methyltetra‐hydrofuran, wherein τ = 4.5 ps for charge separation and τ = 660 ps for charge recombination. Excited‐state symmetry breaking in 5PMI dimers provides new routes to biomimetic charge separation and storage assemblies that can be more easily prepared and modified than those based on multiple tetrapyrrole macrocycles.
Electronic Circular Dichroism Spectroscopy of 1‐(R)‐Phenylethanol: The “Sector Rule” Revisited and an Exploration of Solvent Effects
Authors: Macleod Neil A. , Butz Patrick , Simons John P. , Grant Guy H. , Baker Christopher M. , Tranter George E. 
Published: November 2004

AbstractThe sensitivity of the electronic circular dichroism (ECD) of a chiral molecule to structural and environmental changes has been investigated using 1‐(R)‐phenylethanol (1‐PE) as the benchmark solute and cyclohexane and water as the trial solvents. Rotatory strengths associated with the π → π* (1Lb) electronic transition have been calculated ab initio for: (a) isolated 1‐PE, as a function of the dihedral angles within its chiral side chain and between the side chain and the aromatic ring: these confirm the validity of the empirical “sector rule” but with the signs reversed; (b) the singly and doubly hydrated clusters of 1‐PE, isolated in the gas phase; (c) 1‐PE and its singly and doubly hydrated clusters embedded in a polarizable dielectric continuum; and (d) 1‐PE in an aqueous solution interacting with the local hydration shell and with the polarizable dielectric continuum, using averaged solute structures computed from the fluctuating solute and solvent configurations generated via molecular dynamics simulations.The ab initio calculations (conducted with GAUSSIAN 98) employed configuration interaction singles (CIS) or time‐dependent density functional theory (TD‐DFT) procedures using basis sets of double‐ and triple‐zeta quality. The results have been related to experimental observations and discussed in terms of changes in the molecular geometry and solvent‐induced perturbations.
Isotope Effects in the High‐Overtone Spectrum of C‐H Stretches in HCN
Authors: Sage Martin L. 
Published: November 2004

AbstractThe same Morse potential predicts the vibrational overtone spectra for the various isotopomers of HCl. However, the C‐H stretching overtones of HCN require different Morse parameters for different isotopomers. This paper considers how the other vibrational coordinates change the frequency of the C‐H overtones. A simple model is used that considers the C‐H to be a Morse oscillator and the other motions to be harmonic oscillators. The change in bending frequency with overtone level and kinetic coupling between the two stretching motions accounts for the observed C‐H overtone spectrum. The simple Morse potential that accounts for a single isotopomer is only an effective potential.
Novel Synthesis of Ordered MCM‐41 Titanosilicates with Very High Titanium Content via Ultrasound Radiation
Authors: Tang Xianghai , Wen Xin , Huang Weiping , Liu Suwen , Wang Yanqin , Palchik Oleg , Koltypin Yuri , Pickup David M. , Van Eck Ernst R.H. , Gedanken Aharon 
Published: November 2004

AbstractA novel synthetic strategy has been developed for the fabrication of mesostructured titanosilicate with very high titanium content. By the combination of ultrasound radiation and a separate hydrolysis procedure, highly ordered MCM‐41 titanosilicates can be synthesized within 3 h from gels with Ti/Si ratios up to 1. The physicochemical properties of the materials were characterized by means of XRD, TEM, FT‐IR, UV‐Vis DRS, 29Si MAS NMR, and liquid nitrogen adsorption‐desorption measurements. The results suggested that during crystallization, sonication re‐dispersed and accelerated the condensation of inorganic species, and resulted in more condensed pore walls compared to those synthesized with the conventional methods. The presence of silica and ultrasound radiation remarkably suppressed the aggregation of titanium species, thus, at the medium titanium level, a relatively homogeneous dispersion of titanium within the MCM‐41 framework was attained.
Magnetic Nanocrystals Aligned on Mesoscopic Scale: Collective Properties and Their Use
Authors: Pileni Marie Paule , Ingert Dorothée , Lalatonne Yoann , Lisiecki Isabelle , Ngo Anh‐Tu , Motte Laurence , Petit Christophe , Russier Vincent 
Published: November 2004

AbstractMagnetic nanocrystals organized in chain‐like structures behave as nanowires with a shape anisotropy induced by the structuration of the sample. This is valid for various types of magnetic nanomaterials. Furthermore, the coating of nanocrystals plays a major role in the mesoscopic structure of the film. γ‐Fe2O3 nanocrystals are used as a mask to reproduce the mesoscopic structure on a silicon wafer.
Playing With a Pair of Ultracold Atoms and Lasers: Towards a Novel Ultracold Photochemistry?
Authors: Dulieu Olivier , Pillet Pierre 
Published: November 2004

AbstractThe use of photoassociation of cold atoms has permitted the first demonstration of ultracold molecules in the microKelvin range. In this article we report the mechanisms and the dynamics studied in the case of the cesium dimer. The first key point is the efficiency of photoassociation for long‐range molecules, which involves a R−3 long‐range potential (R = interatomic distance) due to the dipole‐dipole interaction in the electronically excited potentials. The second one is the existence of the Condon point at intermediate distance to “stabilize” the electronically excited molecules reached by photoassociation after spontaneous decay towards ground state. Several molecular configurations are analyzed such as the so‐called double‐well route or the internal coupling route. We show the possibility to extend these concepts to the case of heteronuclear systems.
An Experimental Charge Density Study of the N‐H+…O−Bonds in a Proton‐Transfer System in Comparison with Regular N‐H…O and O‐H…N Hydrogen Bonds
Authors: Ranganathan Anupama , Kulkarni G.U. , Rao C.N.R. 
Published: November 2004

AbstractAn experimental charge density study has been carried out on N‐H+…O−bonds in the proton‐transfer compound piperazinium oxalate as well as on the normal O‐H…N bonds in the thiodiglycolic acid‐4,4′‐bipyridine complex, based on X‐ray diffraction measurements at 130 K. The results are compared with those of the normal N‐H…O bonds in 5‐nitrouracil. In spite of the different crystal geometries, the N‐H+…O−and the N‐H…O bonds exhibit similar values of electron density and the associated curvatures at the hydrogen‐acceptor bond critical points (BCPs). Surprisingly, the polarization parameters of the two BCPs are comparable (˜20%). The pseudoatomic charge on the protonated N atom (in N‐H+…O−) is, however, much smaller (‐0.05e) in comparison to the unprotonated case (˜ ‐0.2e). The O‐H…N hydrogen bonds exhibit shorter H…N distances compared to the charged and the uncharged H…O bonds. Accordingly, the electron densities and the curvatures evaluated at the H…N critical points are also much higher.
Collisions Transfer Coherence
Authors: Bargheer Matias , Gühr Markus , Schwentner Nikolaus 
Published: November 2004

AbstractUltrafast photoexcitation of molecules prepares coherent superpositions of vibrational states, forming wave packets. We show direct experimental evidence that impulsive collisions of photo‐fragments with large energy loss generate new coherent superpositions of vibrational states, causing coherence among previously unoccupied states. We demonstrate the effect in the model system of I2 molecules in Kr solids. This coherence transfer—even in the presence of very strong dissipation—may be used for control strategies in condensed‐phase photoreactions.
Electron Transfer and Redox Metalloenzyme Catalysis at the Single‐Molecule Level
Authors: Hansen Allan G. , Zhang Jingdong , Christensen Hans E. M. , Welinder Anne C. , Wackerbarth Hainer , Ulstrup Jens 
Published: November 2004

AbstractVoltammetry based on single‐crystal, atomically‐planar metal electrodes is novel in bioelectrochemistry. Together with in situ scanning tunneling microscopy (STM) directly in aqueous buffer, single‐crystal voltammetry has disclosed new detail in molecular adsorption and interfacial electron transfer (ET). Image interpretation requires, however, theoretical support, as STM represents both electronic and topographic features. Molecules with accessible redox levels offer other insight into electron tunneling mechanisms, addressed in detail for ET metalloproteins. We present here in situ STM of the blue redox metalloenzyme copper nitrite reductase (Achromobacter xylosoxidans, Ax CuNiR) on Au(111) electrode surfaces modified by a self‐assembled cysteamine monolayer. Ax CuNiR displays strong nitrite reduction waves in this environment. Ax CuNiR/cysteamine/Au(111) surfaces were imaged at KNO2 concentrations where most of the enzyme is in the enzyme‐substrate bound state.Molecular resolution for both cysteamine/Au(111) and Ax CuNiR/cysteamine/Au(111) electrode surfaces was achieved. The enzyme coverage is about 1.5 × 10−13 mol cm−2, which is low compared with an ideal close‐packed monolayer. The adlayer behaves as an assembly of individual molecules, reflected in distributions of molecular appearance, although a number of molecules do show the triangular shape of the trimeric Ax CuNiR structure. The apparent average molecular height is about 11 Å. This suggests that details of electronic structures and larger assemblies are needed to disentangle enzyme mechanisms at the single‐molecule level.
Mathematical modeling of the porosity of suspension poly(vinyl chloride)
Authors: Márquez Esteban F. , Lagos Luis L. 
Published: November 2004

AbstractA mathematical model that describes the effect of conversion and polymerization temperature on the porosity of suspension poly(vinyl chloride) is proposed. The model considers that the packing of the primary particles that develop in the polymerizing drop begins at a conversion at which the particles become motionless. The model considers the morphology of the primary particles as a group of particles with a particular sphericity that form a network whose porosity decreases as conversion increases. Furthermore, the model considers the effect on porosity of the desorption of residual monomer and the difference in contraction and deformation between the pericellular membrane and the network of particles. The model contains three parameters that are estimated from data reported in the open literature. The agreement between experimental data and the theoretical predictions of the model are satisfactory. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3184–3194, 2004
Ornithine decarboxylase activity during the development of Anastrepha fraterculus (Diptera, Tephritidae)
Authors: Cardoso V.V. , Prestes P.R. , Casali E.A. , Moreira J.C.F. , Oliveira A.K. 
Published: November 2004

AbstractOrnithine decarboxylase (ODC) (EC 4.1.1.17) is very important for polyamine biosynthesis, which is required for main biological events. In the present study, ODC activity was measured in samples of Anastrepha fraterculus's egg, larva, pupa body and abdomen, adult body, ovaries, and fat body of young females, and in ovaries of mature flies. The kinetic parameters (Km app and Vmax) for ODC activity were determined for pupa, larva, and young ovary. ODC activity showed fluctuations during A. fraterculus's life development. In its earlier stages, prior to emergence, the egg has high ODC‐specific activity probably due to embryogenesis, which is characterized by a high rate of cell division. This enzyme activity is also significantly high in the ovary and fat body of young females possibly related to the increased oogenesis and vitellogenesis. The kinetic parameters (Km app and Vmax) had great variation. Our results using GTP showed that the great variation in kinetic parameters can be accounted for by post‐translational modifications. Arch. Insect Biochem. Physiol. 57:151–159, 2004. © 2004 Wiley‐Liss, Inc.
An Electronic Perspective on the Reduction of an NN Double Bond at a Conserved Dimolybdenum Core
Authors: Padden Metzker Julia K. , McGrady John E. 
Published: November 2004

AbstractDensity functional theory has been used to assess the role of the bimetallic core in supporting reductive cleavage of the NN double bond in [Cp2Mo2(μ‐SMe)3(μ‐η1:η1‐HNNPh)]+. The HOMO of the complex, the Mo–Mo δ orbital, plays a key role as a source of high‐energy electrons, available for transfer into the vacant orbitals of the NN unit. As a result, the metal centres cycle between the MoIII and MoIV oxidation states. The symmetry of the Mo–Mo δ “buffer” orbital has a profound influence on the reaction pathway, because significant overlap with the redox‐active orbital on the NN unit (π* or σ*) is required for efficient electron transfer. The orthogonality of the Mo–Mo δ and N–N σ* orbitals in the η1:η1 coordination mode ensures that electron transfer into the N–N σ bond is effectively blocked, and a rate‐limiting η1:η1→η1 rearrangement is a necessary precursor to cleavage of the bond.
Comparison of plasma‐sprayed hydroxyapatite coatings and zirconia‐reinforced hydroxyapatite composite coatings: In vivo study
Authors: Lee T. M. , Yang C. Y. , Chang E. , Tsai R. S. 
Published: November 2004

AbstractThe clinical use of plasma‐sprayed hydroxyapatite (HA) coatings on metal implants has been widely adopted because the HA coating can achieve the firmly and directly biological fixation with the surrounding bone tissue. However, the long‐term mechanical properties of HA coatings has been concern for the long‐term clinical application. Previous research showed that the concept of adding ZrO2 as second phase to HA significantly increased the bonding strength of plasma‐sprayed composite material. The present work aimed to explore the biological properties, including the histological responses and shear strength, between the plasma‐sprayed HA and HA/ZrO2 coating, using the transcortical implant model in the femora of canines. After 6 and 12 weeks of implantation, the HA coating revealed the direct bone‐to‐coating contact by the backscattered electron images (BEIs) of scanning electron microscope (SEM), but the osseointegration was not observed at the surface of HA/ZrO2 coating. For new bone healing index (NBHI) and apposition index (AI), the values for HA implants were significantly higher than that for HA/ZrO2 coatings throughout all implant periods. After push‐out test, the shear strength of HA‐coated implants were statistically higher than HA/ZrO2 coated implants at 6‐ and 12‐week implantation, and the failure mode of HA/ZrO2 coating was observed at the coating‐bone interface by SEM. The results indicate that the firm fixation between bone and HA/ZrO2 has not been achieved even after 12‐week implantation. Consequently, the addition of ZrO2 could improve the mechanical properties of coatings, while the biocompatibility was influenced by the different material characteristics of HA/ZrO2 coating compared to HA coatings. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 652–660, 2004
Human endothelial cell attachment and proliferation on a novel vascular graft prototype
Authors: Knetsch Menno L. W. , Aldenhoff Yvette B. J. , Schraven Martijn , Koole Leo H. 
Published: November 2004

AbstractA new vascular prosthesis prototype was assessed for its ability to support an endothelial cell layer in vitro. A coiled tubular structure, constructed from polymer‐coated metallic wires, with an internal diameter of 690 μm, was used. Addition of heparin to the surface coating of the coil strongly enhanced the blood compatibility of the device. A series of coils with five different coatings, increasing in hydrophilicity, was studied. Heparin was added to one series, another series did not contain this anticoagulant drug. Upon contact with blood, a vascular prosthesis will instantaneously adsorb plasma proteins on its surface, and these proteins will influence the behavior of cells binding to the device. When coils were treated with human plasma proteins, mimicking the in vivo situation, human microvascular endothelial cells grew well on all coils studied, irrespective of the hydrophilicity of the underlying coating or the addition of heparin. For control coils, only endothelial cell growth on the most hydrophobic surfaces, and a moderate enhancing effect for heparin, were observed. This novel vascular graft prototype seems well suited for the support of an endothelial cell layer, especially when plasma proteins are adsorbed to its surface, and shows promise for in vivo testing. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 615–624, 2004
Wheat digalactosyldiacylglycerol molecular species profiling using porous graphitic carbon stationary phase
Authors: Deschamps Frantz S. , Gaudin Karen , Baillet Arlette , Chaminade Pierre 
Published: November 2004

AbstractThe potential of porous graphitic carbon stationary phase (PGC) was assessed for the separation of molecular species of digalactosyldiacylglycerol (DGDG). Detection was by an evaporative light scattering detector (ELSD). A conventional optimization strategy allowed definition of a quaternary non‐aqueous mobile phase and separation of 9 wheat DGDG molecular species with isocratic elution: methanol/toluene/tetrahydrofuran/chloroform 64.3/21.5/13.7/0.5 v/v with 0.1% of triethylamine and a stoichiometric amount of formic acid. The molecular species were identified by LC/MS. The chromatographic behavior of DGDG on PGC was then compared to previous studies. The addition of a carbon double bond on the alkyl chain decreased the retention. This contribution was less important when the number of unsaturations increased in the alkyl chain. The consequence of this retention behavior with PGC was an elution order of molecular species which did not agree with the partition number as observed with C18 grafted stationary phases.