bluuebunny/crossref_metadata_2025 huggingface dataset:
High-pressure spectroscopic probe of hydrophobic hydration of the methyl groups in dimethyl sulfoxide
Authors: Chang Hai-Chou , Jiang Jyh-Chiang , Feng Chun-Min , Yang Yu-Chuan , Su Chih-Chia , Chang Pei-Jung , Lin Sheng Hsien
Published: January 2003

The hydrophobic hydration of dimethylsulfoxide (DMSO)/D2O was explored using a combination of the high-pressure method and ab initio calculations. The frequencies of the C–H stretching vibration of DMSO increase as the mole fraction of D2O increases, while no appreciable changes in spectral shapes are observed upon dilution. Interestingly, the infrared spectra of DMSO/D2O observed under high-pressure exhibits dramatic changes, while the new spectral features locating at ∼2942 and ∼3033 cm−1 appear. The spectral changes were attributed to the combined effect of C–H–O hydrogen bonding between C–H in DMSO and oxygen atom in D2O, a phase change, pressure increase, etc. Ab initio calculation results, forecasting the frequency shift of the C–H stretching vibration as C–H–O is interacting via hydrogen bonding, are discussed. The reorganization of the hydrogen-bond network or geometry may be responsible for spectral changes as the pressure was elevated.
On the physical mechanisms of two-way coupling in particle-laden isotropic turbulence
Authors: Ferrante A. , Elghobashi S.
Published: January 2003

The objective of the present study is to analyze our recent direct numerical simulation (DNS) results to explain in some detail the main physical mechanisms responsible for the modification of isotropic turbulence by dispersed solid particles. The details of these two-way coupling mechanisms have not been explained in earlier publications. The present study, in comparison to the previous DNS studies, has been performed with higher resolution (Reλ=75) and considerably larger number (80 million) of particles, in addition to accounting for the effects of gravity. We study the modulation of turbulence by the dispersed particles while fixing both their volume fraction, φv=10−3, and mass fraction, φm=1, for three different particles classified by the ratio of their response time to the Kolmogorov time scale: microparticles, τp/τk≪1, critical particles, τp/τk≈1, large particles, τp/τk>1. Furthermore, we show that in zero gravity, dispersed particles with τp/τk=0.25 (denoted here as “ghost particles”) modify the spectra of the turbulence kinetic energy and its dissipation rate in such a way that keeps the decay rate of the turbulence energy nearly identical to that of particle-free turbulence, and thus the two-way coupling effects of these ghost particles would not be detected by examining only the temporal behavior of the turbulence energy of the carrier flow either numerically or experimentally. In finite gravity, these ghost particles accumulate, via the mechanism of preferential sweeping resulting in the stretching of the vortical structures in the gravitational direction, and the creation of local gradients of the drag force which increase the magnitudes of the horizontal components of vorticity. Consequently, the turbulence becomes anisotropic with a reduced decay rate of turbulence kinetic energy as compared to the particle-free case.
Dean vortices-induced enhancement of mass transfer through an interface separating two immiscible liquids
Authors: Gelfgat A. Yu. , Yarin A. L. , Bar-Yoseph P. Z.
Published: January 2003

Two-fluid Dean vortex flow in a coiled pipe with vanishing torsion, and its effect on the mass transfer through the liquid–liquid interface of two immiscible fluids are studied numerically. The liquids are stratified by gravity, with the denser one occupying the lower part of the pipe. The Navier–Stokes equations in both fluid layers are solved numerically by the finite volume method. The results reveal a detailed structure of the transverse flow (the Dean vortices) in coiled pipes with the dimensionless curvature 0.1. Both cocurrent and countercurrent axial flows in the fluid layers are considered. Using the flow fields predicted, the mass transfer equation is solved. It is shown that the mass transfer of a passive scalar (say, a protein with the Schmidt number of the order of 103) through the interface can be significantly enhanced by the Dean vortices, so that the mass transfer rate can be increased by three to four times. This makes the Dean vortex flow an effective tool for mass transfer enhancement at the liquid–liquid interface. It is shown that the Dean flow provides a stronger mixing than the Taylor–Couette flow. It is also shown that there exists an optimal axial flow rate in terms of this enhancement. The optimal flow corresponds to the value of the Dean number of about 180. In the countercurrent flow case the Dean vortices can split, which has a negative effect on the mass transfer enhancement. Both the cocurrent and countercurrent axial flows yield a similar enhancement effect on the interfacial mass transfer rate. The problem is related to the search for novel bioseparator devices.
Rotational spectrum, dynamics, and bond energy of the floppy dimethylether⋯neon van der Waals complex
Authors: Maris Assimo , Caminati Walther
Published: January 2003

The equilibrium conformation, dynamics, and dissociation energy of the weakly bonded dimethylether⋯Ne complex have been deduced from its pulsed jet millimeter wave spectrum. Each rotational transition is split into two component lines. The corresponding vibrational splitting has been determined to be ΔE=807.2(9) MHz. The inversion barrier between the two equivalent minima with Ne above or below the COC plane has been calculated from this datum to be 16 cm−1. The dissociation energy of the complex is estimated, from the centrifugal distortion constant DJ, to be ca. 1.0 kJ/mol.
Numerical simulations of the Lagrangian averaged Navier–Stokes equations for homogeneous isotropic turbulence
Authors: Mohseni Kamran , Kosović Branko , Shkoller Steve , Marsden Jerrold E.
Published: January 2003

Capabilities for turbulence calculations of the Lagrangian averaged Navier–Stokes (LANS-α) equations are investigated in decaying and statistically stationary three-dimensional homogeneous and isotropic turbulence. Results of the LANS-α computations are analyzed by comparison with direct numerical simulation (DNS) data and large eddy simulations. Two different decaying turbulence cases at moderate and high Reynolds numbers are studied. In statistically stationary turbulence two different forcing techniques are implemented to model the energetics of the energy-containing scales. The resolved flows are examined by comparison of the energy spectra of the LANS-α with the DNS computations. The energy transfer and the capability of the LANS-α equations in representing the backscatter of energy is analyzed by comparison with the DNS data. Furthermore, the correlation between the vorticity and the eigenvectors of the rate of the resolved strain tensor is studied. We find that the LANS-α equations capture the gross features of the flow, while the wave activity below the scale α is filtered by a nonlinear redistribution of energy.
Statistical analysis of coherent vortices near a free surface in a fully developed turbulence
Authors: Nagaosa Ryuichi , Handler Robert A.
Published: January 2003

The dynamics of coherent vortices, their interactions with an unsheared gas–liquid interface, i.e., free surface, and their contribution to turbulent heat transfer has been investigated in a fully developed turbulence using the results from a direct numerical simulation. Fully resolved free surface turbulence simulations were performed at Reynolds numbers of 150 and 300 based on the wall shear velocity and water depth. Passive heat transfer at a Prandtl number of 1 is enforced by imposing a constant temperature difference between the bottom no-slip boundary and free surface. Instantaneous turbulent flow realizations are stored and used to establish a database from which the statistical properties of the flow can be established. The three-dimensional two-point correlations between the total heat flux at the free surface and the subsurface hydrodynamics are evaluated to determine the spatial extent of the coherent vortices which contribute to the enhancement of heat transport at the free surface. A conditional averaging technique is also used to explore the structure of the typical coherent vortices which promote heat transfer at the interface. The two-point correlation technique reveals ring-like coherent vortices in the subsurface region, which are comprised of a vortex pair and spanwise vortices. The conditional averaging strategy is also applied to an intense ejection (second quadrant) event to examine dynamics of coherent vortices and their development. The results of the statistical analysis near the second quadrant event reveals a hairpin-like vortex, known as a bursting eddy, which is generated in the near-wall region and advects toward the free surface. The eddy then changes its shape to a ring-like structure as it approaches very near to the free surface. Backward tracking of the ring-like vortex shows that its origin is clearly a near-wall hairpin-like bursting vortex associated with the ejection of low-speed fluid in the direction normal to the wall. The interaction of the ring-like vortex with the free surface produces a splat event, which involves fluid impingement onto the free surface from the turbulent bulk, an event which intensifies the local temperature gradient at the free surface. It is also found that turbulent shear layers, which can be identified as regions of intense spanwise vorticity, impact onto the free surface, accompanying the interaction of the ring-like vortex with the free surface.
On the hydrodynamic stability of channel flow with cross flow
Authors: Fransson Jens H. M. , Alfredsson P. Henrik
Published: January 2003

We study plane channel flow, with a homogeneous cross flow through porous walls, mainly with respect to the stability to two-dimensional wave disturbances. Since the stability of a shear flow depends both on the velocity distribution and the Reynolds number we partly investigated this flow under the conditions that the flow Reynolds number was constant. The flow exhibits some interesting and unexpected stability characteristics. The effect of the cross flow was for certain parameter regions stabilizing and for others destabilizing. The latter result is in contrast to previous studies.
Polarization dynamics and retention loss in fatigued PbZr0.4Ti0.6O3 ferroelectric capacitors
Authors: Kang B. S. , Yoon Jong-Gul , Noh T. W. , Song T. K. , Seo S. , Lee Y. K. , Lee J. K.
Published: January 2003

Short-time retention loss behaviors were investigated for fatigued Pt/PbZr0.4Ti0.6O3/Pt capacitors. In the short-time regime of t<1 s, fatigued capacitors showed a significant loss in retained polarization, which could be well described by a power-law function. This behavior was interpreted in terms of a superposition of polarization relaxations with a relaxation time distribution. The effects of the pulse voltage on the relaxation time distribution suggested that the retention loss should be activated by a depolarization field. As the fatigue stress was applied, the retention loss became worse. This effect can be explained in terms of the increase of the depolarization field, possibly due to the growth of an interfacial passive layer.
Enhanced low temperature electrical activation of B in Si
Authors: Kalyanaraman Ramki , Venezia V. C. , Pelaz L. , Haynes T. E. , Gossmann H.-J. L. , Rafferty C. S.
Published: January 2003

The electrical activation of B in n-type epitaxial-Si(100) has been enhanced in the temperature range of 400–800 °C. This enhanced activation was measured for 40 keV, 2×1014 cm−2 dose of B implanted into a vacancy-rich Si region. The vacancy-rich region consists of excess vacancies (Vex) generated by a 2 MeV Si implant in the dose range of 3×1015–10×1015 cm−2. The B activation in vacancy-rich Si is found to be a factor of ∼2.4 larger with up to ∼80% of the B activated as compared to similar B implant and activation anneals carried out in the bulk Si. The dependence of B activation on Vex concentration shows that the active B concentration increases with the Vex concentration. From this dependence it was estimated that at least three vacancies are required to activate an additional B atom. This process is distinctly different from the low temperature activation that occurs during solid-phase epitaxial recrystallization of B-doped amorphous Si as no amorphous Si is produced during any step. This low temperature processing will be advantageous in situations where the epitaxial recrystallization of a doped amorphous Si layer is not possible, for instance in the fabrication of fully depleted Si-on-insulator devices.
Combinatorial near-edge x-ray absorption fine structure: Simultaneous determination of molecular orientation and bond concentration on chemically heterogeneous surfaces
Authors: Genzer Jan , Fischer Daniel A. , Efimenko Kirill
Published: January 2003

We show that simultaneous molecular orientation and bond chemistry of planar chemically heterogeneous surfaces can be obtained by combining near-edge x-ray absorption fine structure (NEXAFS) spectroscopy and rastering the incident x-ray beam on the specimen. This rastering produces serially two-dimensional NEXAFS images in space and energy, revealing information about the chemistry (including bond concentration) and orientation of the surface-bound molecules with submillimeter planar spatial resolution and submonolayer molecular sensitivity. We illustrate the power of the combinatorial NEXAFS method by simultaneously probing the concentration and molecular orientation of semifluorinated (SF) molecules in double-SF molecular gradients on flat silica substrates.
Size-dependent Raman study of InP quantum dots
Authors: Seong M. J. , Mićić Olga I. , Nozik A. J. , Mascarenhas A. , Cheong Hyeonsik M.
Published: January 2003

Raman spectrum of a quantum dot (QD) is characterized by transverse (TO) and longitudinal (LO) optical modes as well as surface optical modes, occurring between the TO and LO modes. We have studied in detail the size-dependence of the Raman spectrum of InP QD of diameter larger than 35 Å. The LO phonon frequency decreases while the TO phonon frequency increases with decreasing QD size. The linewidth of the LO phonon broadens and the broadening becomes increasingly asymmetrical towards the low frequency side as the QD size decreases. By analyzing the Raman intensity ratio of the LO phonon to its overtone, we find that the electron-phonon coupling decreases with decreasing QD size.
Far-infrared absorption spectra and properties of SnO2 nanorods
Authors: Liu Yingkai , Dong Yi , Wang Guanghou
Published: January 2003

Gray-colored materials synthesized by calcining the precursor powders, which were produced in a microemulsion, are identified to be rutile structured SnO2 nanorods 20–45 nm in diameter and several micrometers in length by x-ray diffraction, transmission with electron microscopy, and high-resolution transmission microscopy. Conspicuous far-infrared (FIR) absorption spectrum platform peaks with widths of up to 61.6 and 119 cm−1 are observed, and are explained as the overlap of the surface modes of cylindrical and spheroid particles. Good agreement is achieved between FIR platform peaks and calculated results.
Dual accumulation and depletion behaviors of the arsenic precipitation in low-temperature-grown Be delta-doped GaAs
Authors: Huang J. H. , Hsieh L. Z. , Guo X. J. , Su Y. O.
Published: January 2003

The precipitation of arsenic in annealed Be delta-doped GaAs grown by low-temperature molecular-beam epitaxy has been studied using transmission electron microscopy. It was found that the planes doped with [Be]=1.0×1014 cm−2 always accumulate As precipitates, while the planes doped with [Be]=1×1013 cm−2 tend to deplete As precipitates. In contrast, the planes doped with [Be]=3 and 2×1013 cm−2 exhibit a weak accumulation property when annealed at 700 °C, but a depletion property when annealed 800 °C. The existence of twins and/or precipitates around the [Be]=1.0×1014 cm−2 doped planes found in the as-grown sample suggests a strain-induced mechanism to account for the As precipitates accumulation on these planes.
Crystalline boron nanowires
Authors: Wang Y. Q. , Duan X. F.
Published: January 2003

Crystalline boron nanowires were produced through post-annealing amorphous boron nanowires synthesized by rf magnetron sputtering. High-resolution transmission electron microscopy was used to characterize the microstructure of the crystalline boron nanowires. Selected-area electron diffraction studies showed that the crystalline boron nanowires belong to a rhombohedral structure (β-boron), with lattice parameters of a=10.95 Å and c=23.82 Å. Electron energy-loss spectroscopy was used to characterize the chemical composition of the boron nanowires.
Proposal for all-electrical measurement of T1 in semiconductors
Authors: Žutić Igor , Fabian Jaroslav , Sarma S. Das
Published: January 2003

In an inhomogeneously-doped magnetic semiconductor, spin relaxation time T1 can be determined by all-electrical measurements. Nonequilibrium spin injected in a magnetic p–n junction gives rise to the spin-voltaic effect, in which the nonequilibrium spin-induced charge current is very sensitive to T1 and can flow even at no applied bias. It is proposed that T1 can be determined by measuring the I–V characteristics in such a geometry. In a magnetic p–n junction, for which the results can be calculated analytically, it is also possible to extract the g-factor and the degree of injected-carrier spin polarization.
Time-resolved photoelectron imaging of the photodissociation of I2−
Authors: Davis Alison V. , Wester Roland , Bragg Arthur E. , Neumark Daniel M.
Published: January 2003

Time-resolved photoelectron imaging is presented as a new method for the study of anion dynamics. Time-dependent photoelectron energy spectra and angular distributions are extracted from images taken during the dissociation of I2− at 793 nm, and used to follow in detail the dissociation dynamics from 0–1 ps.
Lasing characteristics of InGaAs/InGaAsP multiple-quantum-well optical thyristor operating at 1.561 μm
Authors: Kim Doo Gun , Lee Hee Hyun , Choi Woon Kyung , Choi Young Wan , Lee Seok , Woo Deok Ha , Byun Young Tae , Kim Jae Hun , Kim Sun Ho , Nakano Yoshiaki
Published: January 2003

We present a demonstration of a waveguide-type depleted optical thyristor laser diode with InGaAs/InGaAsP multiple-quantum-well structure. The measured switching voltage and current are 4.63 V and 10 μA, respectively. The holding voltage and current are, respectively, 0.59 V and 20 μA. The lasing threshold currents at 25 °C and 10 °C are 111 mA and 72.5 mA, respectively. The lasing wavelength is centered at 1.561 μm at a bias current equal to 1.41 times threshold.
Imaging properties of a metamaterial superlens
Authors: Fang Nicholas , Zhang Xiang
Published: January 2003

The subwavelength imaging quality of a metamaterial superlens is studied numerically in the wave vector domain. Examples of image compression and magnification are given and resolution limits are discussed. A minimal resolution of λ/6 is obtained using a 36 nm silver film at 364 nm wavelength. Simulation also reveals that the power flux is no longer a good measure to determine the focal plane of superlens due to the elevated field strength at exit side of the metamaterial slab.
Damage coefficient in high-temperature particle- and γ-irradiated silicon p–i–n diodes
Authors: Ohyama H. , Takakura K. , Hayama K. , Kuboyama Satoshi , Deguchi Yasushi , Matsuda Sumio , Simoen E. , Claeys C.
Published: January 2003

The impact of high-temperature neutron, electron, and γ-irradiations on the dark current of silicon p–i–n junctions is described in terms of a damage coefficient KI. It is shown that this KI is thermally activated and reduces for increasing irradiation temperature. The same activation energy is retrieved when studying the isochronal annealing behavior of a set of room-temperature irradiated diodes. This leads to a simple method to predict the high-temperature KI from only room-temperature irradiations combined with a thermal annealing study.
Nanosized iron clusters investigated with in situ transmission electron microscopy
Authors: Vystavel T. , Palasantzas G. , Koch S. A. , De Hosson J. Th. M.
Published: January 2003

Transmission electron microscopy is employed for investigating the structural stability of nanosized iron clusters as deposited and after in situ annealing treatments under high vacuum conditions. The thin iron oxide shell that is formed around the iron clusters (upon air exposure) is of the order of 2 nm surrounding a 5 nm core of body-centered-cubic (bcc) iron. The oxide shell breaks down upon annealing at relatively low temperatures (∼500 °C) leading to pure iron particles having a bcc crystal structure. Annealing of clusters, which are in contact, leads to their fusion and formation of larger clusters preserving their crystallographic structure and being free of any oxide shell. On the other hand, isolated clusters appear rather immobile (upon annealing). The truncated rhombic dodecahedron was found as the most probable shape of the clusters which differs from former theoretical predictions based on calculations of stable structural forms.
Time-resolved electroluminescence of AlGaN-based light-emitting diodes with emission at 285 nm
Authors: Shatalov M. , Chitnis A. , Mandavilli V. , Pachipulusu R. , Zhang J. P. , Adivarahan V. , Wu S. , Simin G. , Khan M. Asif , Tamulaitis G. , Sereika A. , Yilmaz I. , Shur M. S. , Gaska R.
Published: January 2003

We present a study on the time evolution of the electroluminescence (EL) spectra of AlGaN-based deep ultraviolet light-emitting diodes (LEDs) under pulsed current pumping. The EL spectra peaks at 285 nm and 330 nm are found to result from recombination involving band-to-band and free carriers to deep acceptor level transitions. The 330 nm long-wavelength transitions to deep acceptor levels in the p-AlGaN layer as well as the nonradiative processes significantly influence the LED internal quantum efficiency.
High efficiency organic light-emitting devices with Al/NaF cathode
Authors: Lee J. , Park Y. , Kim D. Y. , Chu H. Y. , Lee H. , Do L.-M.
Published: January 2003

An organic light-emitting device (OLED) with an Al/NaF (1.5 nm) cathode exhibited a highly enhanced performance comparable to the one with the best Al/LiF cathode. This suggests that NaF can be an alternative to commonly used LiF interlayer for improved OLED performance. Photoelectron spectroscopy studies revealed that the intensity of the gap states and the amount of the valence band shift at Al/NaF/Alq3 interface surpassed those of Al/LiF/Alq3 interface, suggesting that the observed performance improvement is directly related with these features.
Relationship between interfacial nitrogen concentration and activation energies of fixed-charge trapping and interface state generation under bias-temperature stress condition
Authors: Tan Shyue Seng , Chen T. P. , Ang C. H. , Chan L.
Published: January 2003

The influence of nitrogen concentration at a nitrided oxide/silicon interface on the activation energies of both near-interface fixed-charge trapping and interface state generation caused by negative bias temperature instability stress has been studied quantitatively. It is observed that the charge trapping and the interface state generation have about the same activation energy for a given interfacial nitrogen concentration. In addition, their activation energies are found to follow the same dependence on the nitrogen concentration. The results suggest that the charge trapping and the interface state generation have the same origin. A discussion on the mechanism of the nitrogen effect on the charge trapping and interface state generation is presented.
Rate-dependent indentation hardness of a power-law creep solder alloy
Authors: Ma Xin , Yoshida Fusahito
Published: January 2003

Berkovich depth-sensing indentation tests with different loading rates have been performed on a creep material, Sn–3.5Ag–0.75Cu solder alloy. The resulting indentation load-depth curves are rate dependent and have varying creep penetration depths during the same hold time. Creep indentation hardness H, defined from the concept of “work of indentation,” varies with the volume strain occurring during the creep hold time, which is a measure of creep strain rate ε̇cr. Thus, rate sensitivity m of the indented material can be determined from the ln H vs ln ε̇cr curve. The derived value of m is consistent with the results from conventional uniaxial tensile and compression experiments of bulk solder alloy.
Self-organized growth of single crystals of nanopores
Authors: Langa S. , Tiginyanu I. M. , Carstensen J. , Christophersen M. , Föll H.
Published: January 2003

Self-organized single crystalline two-dimensional hexagonal arrays of pores in InP semiconductor compound are reported. We show that the self-arrangement of pores can be obtained on n-type substrates with (100) and (111) orientations. The long-range order in pore distribution evidenced in (100)InP samples proves to be favored by the so-called nucleation layer exhibiting branching pores oriented along 〈111〉 directions. The combination of long-range order with self-induced diameter oscillations is shown to be promising for nonlithographic growth of three-dimensional pore crystals.
Tuning efficiency and linewidth of electrostatically actuated multiple air-gap filters
Authors: Römer F. , Prott C. , Irmer S. , Daleiden J. , Tarraf A. , Hillmer H. , Strassner M.
Published: January 2003

We investigated the tuning efficiency of electrostatically actuated multiple air-gap filters fabricated in InP for dense wavelength division multiplex applications by comparing measured tuning curves with the results of optical and mechanical simulations. These filters exhibit a record tuning range of 127 nm at 7.3 V tuning voltage. The filters were measured in reflection using standard single mode fiber. The subsequent analysis is based on a one-dimensional electromechanical and optical model providing a reasonable estimation for the pull-in voltage. Optical simulations show that the filter linewidth does not affect the tuning efficiency.
Molecular dynamics simulations of microwave heating of water
Authors: English Niall J. , MacElroy J. M. D.
Published: January 2003

Nonequilibrium molecular dynamics simulations of water in an intense external microwave field have been performed using a rigid/polarizable and a flexible/nonpolarizable potential model, from ambient conditions to supercriticality. The heating profiles were compared to that predicted from a macroscopic energy balance, and the polarizable model was found to be superior in this regard.
Evaluation of cytochrome P4502C9 metabolic activity with tolbutamide in CYP2C9*1 heterozygotes
Authors: Lee Craig R. , Pieper John A. , Hinderliter Alan L. , Blaisdell Joyce A. , Goldstein Joyce A.
Published: January 2003

Objectives

Multiple single‐nucleotide polymorphisms in the gene encoding cytochrome P450 (CYP) 2C9 have been identified, but the functional significance of the various putative defective genotypes in humans merits further study.

Methods

Using tolbutamide as a probe of CYP2C9 activity, we evaluated CYP2C9 phenotype in 15 healthy individuals expressing the CYP2C9*1/*1, *1/*2, and *1/*3 genotypes (n = 5 per group). CYP2C9 genotype was determined by polymerase chain reaction‐restriction fragment length polymorphism methods. Subjects received 500 mg of tolbutamide, with plasma and urine collected over a 24‐hour period. Plasma tolbutamide and urinary tolbutamide, 4′‐hydroxytolbutamide, and carboxytolbutamide concentrations were determined by an HPLC method.

Results

Tolbutamide area under the plasma concentration‐time curve from time zero to infinity [AUC(0‐∞)] significantly increased by 1.5‐fold and 1.9‐fold, respectively, in subjects expressing the CYP2C9*1/*2 and *1/*3 genotypes compared with *1/*1 subjects. Statistically significant reductions in tolbutamide oral clearance (29% and 48%) and formation clearance (38% and 56%) were detected in the *1/*2 and *1/*3 individuals, respectively, compared with *1/*1 subjects. The increases in AUC(0‐∞) and decreases in oral clearance observed in the *1/*3 individuals were also significantly greater than those expressing the *1/*2 genotype (P < .05). The amount of urinary 4′‐hydroxytolbutamide and carboxytolbutamide excreted in the 0‐ to 12‐hour and 6‐ to 12‐hour collection intervals was significantly less in *1/*2 and *1/*3 individuals compared with *1/*1 subjects. With tolbutamide used as a CYP2C9 probe, CYP2C9 genotype was the major determinant of CYP2C9 phenotype (r2 = 0.77)

Conclusions

CYP2C9 activity was significantly reduced in *1 heterozygotes compared with *1 homozygotes, and metabolism was more severely impaired in *1/*3 individuals compared with those expressing *1/*2.

Clinical Pharmacology & Therapeutics (2002) 72, 562–571; doi: 10.1067/mcp.2002.127913
Nimodipine: Drug pharmacokinetics and plasma adenosine levels in patients affected by cerebral ischemia
Authors: Blardi Patrizia , Urso Renato , de Lalla Arianna , Volpi Luciana , Perri Tullio Di , Auteri Alberto
Published: January 2003

Background and Objective

Nimodipine is a dihydropyridine calcium channel blocker used in the treatment of ischemic damage in subarachnoid hemorrhage. Recent investigations have shown that it is able to inhibit adenosine transport in human red blood cells and parietal cortex neurons. In this study we investigated the pharmacokinetics of nimodipine and the effect on plasma adenosine levels in patients affected by cerebral ischemia.

Methods

Twelve patients with cerebral ischemia (9 men and 3 women; mean age, 68.8 ± 11.2 years; mean weight, 67.9 ± 9.3 kg) were admitted to the study. They received nimodipine intravenously (a bolus of 0.03 mg/kg) and orally (single doses of 30, 60, and 90 mg) during different sessions. Blood samples for adenosine and nimodipine were collected at fixed intervals up to 480 minutes. Adenosine and nimodipine plasma levels were detected by HPLC methods.

Results

Both the intravenous and oral administrations induced a statistically significant increase in plasma adenosine levels (P < .001), which appeared to be related to the dose and route of drug administration. In particular, a 67.8% increase was observed after intravenous administration, and increases of 28.9%, 43.6%, and 60.2% were observed after 30 mg, 60 mg, and 90 mg of nimodipine, respectively. The pharmacokinetic parameters of nimodipine after intravenous administration were as follows: peak concentration (Cmax), 319.6 ± 38.9 ng/mL at the first sampling time; area under the curve (AUC), 239 ± 25 ng · h/mL; and terminal half‐life, 3.12 ± 0.97 hours. After oral administration, the drug kinetics was linear in the administered dose range and the pharmacokinetic parameters were as follows: Cmax(30 mg), 46.1 ± 5.8 ng/mL; Cmax(60 mg), 81.7 ± 14.6 ng/mL; Cmax(90 mg), 131.6 ± 16.3 ng/mL; AUC(30 mg), 119 ± 25 ng · h/mL; AUC(60 mg), 256 ± 48 ng · h/mL; and AUC(90 mg), 389 ± 54 ng · h/mL. The half‐life was similar to the values observed after intravenous administration, whereas the bioavailability ranged between 2% and 5.9%.

Conclusions

Our data indicate that the administration of nimodipine induces an increase in plasma adenosine levels, and we hypothesize that the drug activity could be associated, at least partially, with adenosine mediation.

Clinical Pharmacology & Therapeutics (2002) 72, 556–561; doi: 10.1067/mcp.2002.128127
Pharmacokinetics and pharmacodynamics of darbepoetin alfa and epoetin in patients undergoing dialysis*
Authors: Allon Michael , Kleinman Kenneth , Walczyk Michael , Kaupke Charles , Messer‐Mann Louise , Olson Kurt , Heatherington Anne C. , Maroni Bradley J.
Published: January 2003

Objective

The aim of this multicenter, randomized, open‐label study was to compare the pharmacokinetic and pharmacodynamic profiles of darbepoetin alfa, a new erythropoiesis‐stimulating protein, and recombinant human erythropoietin (epoetin) after repeated intravenous dosing in patients with chronic kidney disease receiving hemodialysis.

Methods

Forty‐seven patients were randomized to receive darbepoetin alfa administered once weekly (n = 17) or 3 times weekly (n = 15) or epoetin administered 3 times weekly (n = 15) for up to 52 weeks. Pharmacokinetic profiles were measured during weeks 1 and 12 and at hemoglobin steady state (defined as a hemoglobin concentration within the target range for 4 consecutive weeks after week 12 with no change in study drug dose) or between weeks 36 and 40, whichever occurred first.

Results

At each of the 3 time points evaluated, the terminal half‐life of darbepoetin alfa was 2 to 3 times longer and the clearance approximately 4 times slower than those of epoetin. At week 12, the terminal half‐life was 23.4 hours with darbepoetin alfa once weekly, 18.3 hours with darbepoetin alfa 3 times weekly, and 8.0 hours with epoetin 3 times weekly. The pharmacokinetics of darbepoetin alfa was not dependent on dose or time. Mean hemoglobin values at steady state were all approximately 11 g/dL, within the target range of 9.0 to 13.0 g/dL. Safety analyses revealed no differences between darbepoetin alfa and epoetin.

Conclusions

The pharmacokinetic and pharmacodynamic profiles and safety data for darbepoetin alfa demonstrate that it can be administered less frequently than epoetin in patients with chronic kidney disease receiving hemodialysis, thus simplifying anemia management.

Clinical Pharmacology & Therapeutics (2002) 72, 546–555; doi: 10.1067/mcp.2002.128374
Disposition of nasal, intravenous, and oral methadone in healthy volunteers
Authors: Dale Ola , Hoffer Christine , Sheffels Pamela , Kharasch Evan D.
Published: January 2003

Objective

Nasal administration of many opioids demonstrates rapid uptake and fast onset of action. Nasal administration may be an alternative to intravenous and oral administration of methadone and was therefore studied in human volunteers.

Methods

The study was approved by the Institutional Review Board of the University of Washington, Seattle. Eight healthy volunteers (6 men and 2 women) aged 19 to 33 years were enrolled after informed written consent was obtained. Subjects received 10 mg methadone hydrochloride nasally, orally, or intravenously on 3 separate occasions in a crossover design. Nasal methadone (50 mg/mL in aqueous solution) was given as a 100‐μL spray in each nostril (Pfeiffer BiDose sprayer). Blood samples for liquid chromatography‐mass spectrometry analyses of methadone and the metabolite 2‐ethyl‐1,5‐dimethyl‐3,3‐diphenylpyrrolinium were drawn for up to 96 hours. The methadone effect was measured by noninvasive infrared pupilometry coincident with blood sampling.

Results

Nasal uptake of methadone was rapid, with maximum plasma concentrations occurring within 7 minutes. The maximum effects of intravenous, nasal, and oral methadone, on the basis of dark‐adapted pupil diameter, were reached in about 15 minutes, 30 minutes, and 2 hours, respectively. The respective durations were 24, 10, and 8 hours. Both nasal and oral bioavailabilities were 0.85. Subjects reported that nasal methadone caused a burning sensation.

Conclusions

Nasal administration of methadone results in rapid absorption and onset of effect and high bioavailability, which was greater than that reported for other nasal opioids, with a similar duration of effect. Nasal administration may be an alternative route of methadone administration; however, improved formulations are desirable to reduce nasal irritation.

Clinical Pharmacology & Therapeutics (2002) 72, 536–545; doi: 10.1067/mcp.2002.128386
Sex‐related differences in the clearance of cytochrome P450 3A4 substrates may be caused by P‐glycoprotein
Authors: Cummins Carolyn L. , Wu Chi‐Yuan , Benet Leslie Z.
Published: January 2003

Clinical Pharmacology & Therapeutics (2002) 72, 474–489; doi: 10.1067/mcp.2002.128388
Pharmacokinetics of C1‐inhibitor protein in patients with acute myocardial infarction
Authors: Diris Jart H. C. , Hermens Wim Th. , Hemker Pieter W. , Lagrand Wim K. , Hack C. Erik , van Dieijen‐Visser Marja P.
Published: January 2003

Objectives

C1‐inhibitor protein (C1‐INH) purified from pooled human plasma is used for the treatment of patients with hereditary angioedema. Recently, the beneficial effects of high‐dose C1‐INH treatment on myocardial ischemia or reperfusion injury have been reported in various animal models and in humans. We investigated the pharmacokinetic behavior of C1‐INH in patients with acute myocardial infarction to calculate the amount of C1‐INH required for optimal efficacy.

Methods

Twenty‐two patients received an intravenous loading dose, followed by 48 hours of continuous infusion of C1‐INH. Changes in the endogenous production of C1‐INH were evaluated in 16 control patients with acute myocardial infarction. A 2‐compartment model was used to estimate the fractional catabolic rate constant (FCR), transcapillary escape rate constant (TER), and extravascular return rate constant (ERR) of C1‐INH. Software designed to analyze and fit measured data to unknown parameters in a system of differential equations was used to fit the experimental data against the 3‐parameter model.

Results

With fixed TER and ERR values (0.014 h−1 and 0.018 h−1, respectively), 20 of the 22 cases yielded well‐determined FCR values, and simultaneous fitting resulted in a median FCR of 0.011 h−1 (95% confidence interval, 0.010 to 0.012 h−1) versus 0.025 h−1 as reported in healthy control patients. Simultaneous estimation of TER, ERR, and FCR demonstrated weakly defined TER and ERR values, whereas the median FCR value remained unchanged. The use of a 2‐compartment model resulted in a significantly better fit compared with the 1‐compartment model. Physiologic explanations are offered for discrepancies in the literature.

Conclusions

Dose calculation of C1‐INH in patients treated with massive doses of C1‐INH requires turnover parameters that differ from those found in healthy subjects, possibly because of suppression of continuous C1‐INH consumption by target proteases.

Clinical Pharmacology & Therapeutics (2002) 72, 498–504; doi: 10.1067/mcp.2002.129320
Gender and welfare state change1
Authors: Lewis Jane
Published: January 2003

This paper suggests first, that in the recent literature on welfare states, while family change has received considerable attention, the issue of gender equality has not. Second, it examines the nature of welfare state change, in particular the recasting of the work/welfare relationship, focusing on the UK in comparative perspective. Building on Peter Hall's (1993) framework, the paper argues that the policy developments associated with the new work/welfare relationship represent very different levels of change in different countries. Nevertheless, from a gender perspective, it is argued that the changes amount to a modification of the masculinist model of work and welfare and its generalization to women. This has profound (and sometimes ambiguous) implications for women's role as unpaid carers. Finally, the paper suggests that a gender-centred model of welfare state change highlights the need to develop policies that value and redistribute care work, and in particular that address the issue of time.
Early exit from the labour force between exclusion and privilege: Unemployment as a transition from employment to retirement in West Germany
Authors: Knuth Matthias , Kalina Thorsten
Published: January 2003

Over the past twenty-five years, unemployment has been growing continuously in West Germany. In this study one of the reasons for growing unemployment is analysed: unemployment of older people in their transition from employment to retirement. First, the different possibilities of transitions into retirement are explained within the framework of social security regulations. Taking this legal framework as a starting point, early retirement passages are then modelled with the IAB unemployment sub-sample. It will be shown that - due to the long duration of these unemployment episodes - early retirement contributed considerably to the rise of total unemployment. Early retirement patterns will be broken down by economic sub-sectors and establishment size. It turns out that this kind of unemployment originates primarily from large establishments in manufacturing and extractive industries. Multivariate analysis presented at the end of the paper also includes personal characteristics such as gender or skills and income levels. In the light of these findings, the ‘push’ and ‘pull’ hypothesis common in explaining early exit are discussed. Drawing on the statistical findings as well as on the institutional analysis, it is argued that both kinds of factors are at work.
Quasi-exceptional sets and equivariant coherent sheaves on the nilpotent cone
Authors: Bezrukavnikov Roman
Published: January 2003

A certain

t
t

-structure on the derived category of equivariant coherent sheaves on the nil-cone of a simple complex algebraic group is introduced by the author in the paper Perverse coherent sheaves (the so-called perverse

t
t

-structure corresponding to the middle perversity). In the present note we show that the same

t
t

-structure can be obtained from a natural quasi-exceptional set generating this derived category. As a consequence we obtain a bijection between the sets of dominant weights and pairs consisting of a nilpotent orbit, and an irreducible representation of the centralizer of this element, conjectured by Lusztig and Vogan (and obtained by other means by the author in the paper On tensor categories attached to cells in affine Weyl groups, to be published).
The ELectronic Society for Social Scientists: from journals as documents to journals as knowledge exchanges
Authors: La Manna Manfredi , Young Jean
Published: January 2003

The ELectronic Society for Social Scientists (ELSSS) envisages a new concept of scholarly and scientific journal: conceived and managed by academics themselves; aimed at providing direct competition to high‐priced commercial publications; based on a business model whereby subscription revenues cover the non‐trivial cost of peer‐review; designed to maximise research productivity; intended as a platform for scientific and scholarly debate. The ELSSS model conceives the peer‐reviewed published article not at the final stage of the scholarly communication chain, but as an intermediate step, to be followed by Web‐based interaction among self‐selected networks of interested researchers. The paper suggests that the very concepts of “lending” and “document” need redefining in the case of the forthcoming generation academic‐led journals.
Improving access: is there any hope?
Authors: Friend Frederick J.
Published: January 2003

World‐wide calls for improvements in access to journal literature are being answered by a plethora of projects and services. Consortial purchasing, national licences and “big deals” dominate changes in collection development. Moves to set up affordable easy‐to‐use electronic document delivery services offer an alternative model based on single‐article purchase. More radical barrier‐free access models are moving the economic emphasis away from purchasing to input‐payments. Are all these projects and services making a difference or will access to journal literature be no better in years to come than it is now? It is arguable that only those initiatives which are developing new models through collaboration between the stakeholders will succeed in making a major breakthrough in access.
Interlending and document supply: a review of recent literature – XLIII
Authors: McGrath Mike
Published: January 2003

The Budapest Open Access Initiative has sparked a new round of papers and news items on open access initiatives. Their growth approaches critical mass and all players, including paid for document delivery agents, need to look to their laurels. Copyright remains an old perennial, but more so at present with the implementation date for the new EU directive approaching. Heads must come out of the sand at last if libraries are to apply the new rules efficiently. Other issues that are prominent in the literature this quarter will come as no surprise to readers – electronic journals and site licensing, resource sharing and full text retrospective conversion. At last there is more and better systematic attention being paid to the end user and ILDS will reflect and develop this welcome move.
Synthesis and characterization of Cu (II) complexes with some thiazole dye derivatives and its application in corrosion inhibition
Authors: El‐Mossalomy E.H. , Ibrahim A.A.
Published: January 2003

Cu(II) complexes with some hydroxy azo compounds derived from thiazole and benzothiazole have been synthesized. The structures of the complexes are inferred from data of elemental analysis, electronic, IR and H1 NMR spectra. It is found that the Cu(II) coordinated to ligands through the nitrogen atom of azo group and hetero ring. This coordination lead to lower the energy of CT transition of ligands. The effect of molecular structure of the ligands and nature of the metal ion on complex formation are also examined. The free energy and stability constant of complexes formed in solution have been determined spectrophotometrically. Thiazole azo dyes were found to behave as an inhibitor with respect to the corrosion of copper in acidic solutions.
Improvement of white pine wood properties by impregnation with mixtures of methyl methacrylate and phthalimide monomers, subsequent in situ copolymerization
Authors: Mahmoud A.A. , Eissa A.M.F. , Omar M.S. , El‐Sawy A.A. , Shaaban A.F.
Published: January 2003

White pine wood was impregnated with a mixture of methyl methacrylate (MMA) and N‐methacryloyloxyphthalimide and by other three mixtures prepared by mixing MMA and N‐methacryloyloxytetrabromo‐phthalimide. Water uptake of treated wood was found to be 54 per cent after water‐soaking test of 168 h and maximum antiswell efficiency was found to be 48 per cent for treated wood samples with non‐brominated comonomer mixture.
Modelling the adaptation process in interactive business relationships
Authors: Canning Louise , Hanmer‐Lloyd Stuart
Published: January 2003

Places adaptation within the context of firm behaviour in supplier‐customer relationships before going on to review previous adaptation studies. Gives the rationale and outline of the chosen case‐study based research strategy before findings are presented in which the nature of the adaptation process and progression of this process are considered. Concludes by discussing the significance of the findings in terms of understanding of the adaptation process and future research as well as implications for managing this process.
A Quantitative Analysis on Virtual Reality-Based Computer Aided Design System Interfaces
Authors: Chu Chi-Cheng , Mo Jianzhong , Gadh Rajit
Published: January 2003

In this paper, a series of interface tests on interaction approach for the generation of geometric shape designs via multi-sensory user interface of a Virtual Reality (VR) based System is presented. The goal of these interface tests is to identify an effective user interface for VR based Computer-Aided Design (CAD) system. The intuitiveness of the VR based interaction approach arises from the use of natural hand movements/gestures, and voice commands that emulate the way in which human beings discuss geometric shapes in reality. In order to evaluate the proposed interaction approach, a prototypical VR-CAD system is implemented. A series of interface tests were performed on the prototypical systems to determine the relative efficiency of a set of potential interaction approach with respect to specific fundamental design tasks. The interface test and its results are presented in this paper.