bluuebunny/crossref_metadata_2025 huggingface dataset:
A Direct and Accurate Adaptive Semi-Lagrangian Scheme for the Vlasov-Poisson Equation
Authors: Pinto Martin
Published: October 2007

A Direct and Accurate Adaptive Semi-Lagrangian Scheme for the Vlasov-Poisson Equation

This article aims at giving a simplified presentation of a new adaptive semi-Lagrangian scheme for solving the (1 + 1)-dimensional Vlasov-Poisson system, which was developed in 2005 with Michel Mehrenberger and first described in (Campos Pinto and Mehrenberger, 2007). The main steps of the analysis are also given, which yield the first error estimate for an adaptive scheme in the context of the Vlasov equation. This article focuses on a key feature of our method, which is a new algorithm to transport multiscale meshes along a smooth flow, in a way that can be saidoptimalin the sense that it satisfies both accuracy and complexity estimates which are likely to lead to optimal convergence rates for the whole numerical scheme. From the regularity analysis of the numerical solution and how it gets transported by the numerical flow, it is shown that the accuracy of our scheme is monitored by a prescribed tolerance parameter ε which represents the local interpolation error at each time step. As a consequence, the numerical solutions are proved to converge inL∞towards the exact ones as ε and δttend to zero, and in addition to the numerical tests presented in (Campos Pinto and Mehrenberger, 2007), some complexity bounds are established which are likely to prove the optimality of the meshes.
Numerical Approximation of Self-Consistent Vlasov Models for Low-Frequency Electromagnetic Phenomena
Authors: Besse Nicolas , Mauser Norbert , Sonnendrücker Eric
Published: October 2007

Numerical Approximation of Self-Consistent Vlasov Models for Low-Frequency Electromagnetic Phenomena

We present a new numerical method to solve the Vlasov-Darwin and Vlasov-Poisswell systems which are approximations of the Vlasov-Maxwell equation in the asymptotic limit of the infinite speed of light. These systems model low-frequency electromagnetic phenomena in plasmas, and thus "light waves" are somewhat supressed, which in turn allows the numerical discretization to dispense with the Courant-Friedrichs-Lewy condition on the time step. We construct a numerical scheme based on semi-Lagrangian methods and time splitting techniques. We develop a four-dimensional phase space algorithm for the distribution function while the electromagnetic field is solved on a two-dimensional Cartesian grid. Finally, we present two nontrivial test cases: (a) the wave Landau damping and (b) the electromagnetic beam-plasma instability. For these cases our numerical scheme works very well and is in agreement with analytic kinetic theory.
Arbitrary High-Order Finite Element Schemes and High-Order Mass Lumping
Authors: Jund Sébastien , Salmon Stéphanie
Published: October 2007

Arbitrary High-Order Finite Element Schemes and High-Order Mass Lumping

Computers are becoming sufficiently powerful to permit to numerically solve problems such as the wave equation with high-order methods. In this article we will consider Lagrange finite elements of orderkand show how it is possible to automatically generate the mass and stiffness matrices of any order with the help of symbolic computation software. We compare two high-order time discretizations: an explicit one using a Taylor expansion in time (a Cauchy-Kowalewski procedure) and an implicit Runge-Kutta scheme. We also construct in a systematic way a high-order quadrature which is optimal in terms of the number of points, which enables the use of mass lumping, up toP5elements. We compare computational time and effort for several codes which are of high order in time and space and study their respective properties.
On the Numerical Approximation of First-Order Hamilton-Jacobi Equations
Authors: Abgrall Rémi , Perrier Vincent
Published: October 2007

On the Numerical Approximation of First-Order Hamilton-Jacobi Equations

Some methods for the numerical approximation of time-dependent and steady first-order Hamilton-Jacobi equations are reviewed. Most of the discussion focuses on conformal triangular-type meshes, but we show how to extend this to the most general meshes. We review some first-order monotone schemes and also high-order ones specially dedicated to steady problems.
System Planning for Quality Transit Projects
Authors: Laube Melissa M. , Lyons William M. , Allan Darin
Published: October 2007

Years of experience have provided substantial evidence of persistent planning problems that are common to many proposals for major transit investments. These problems frequently are rooted in the system-level planning performed at the scale of the metropolitan area or region. This area is the scale at which different transportation services and modes form an interrelated system for moving people and goods between origins and destinations where the household, employment, and commerce activities occur. System planning provides the big-picture context for foundational planning elements, such as developing a coherent vision for the region's future and translating that vision into concrete goals and objectives, which provide the basis for identifying transportation needs and problems. The usage of potential new transportation infrastructure and major services should be forecasted at the regional level to capture essential travel behavior characteristics. Five system planning activities are particularly necessary to provide the necessary groundwork underpinning successful projects: regional needs identification and prioritization, land use planning coordinated at the level of the metropolitan area, technical analysis and forecasting, early consideration of environmental issues, and financial planning and fiscal constraint. The components of these activities that are most critical to developing successful large-scale transportation projects are discussed, along with associated strategies for improving the linkage between system-level planning and the development of individual projects.
Bursting the Bubble
Authors: Canepa Brian
Published: October 2007

Transit-oriented developments (TODs) in the United States have been modeled almost exclusively with a half-mile radius as a reliable limit for pedestrian walkability from and to a light rail station. New research has emerged to challenge this standard, with data indicating that transit users may be apt to walk greater distances than previously estimated. Variables such as housing density, employment density, and urban design all significantly affect walking patterns. Those factors are analyzed as expanders or contractors of the TOD radius, and the implications that a fluctuating boundary might have on the future of urban growth are considered.
Are Smart Cards the Smart Way to Go?
Authors: Iseki Hiroyuki , Yoh Allison C. , Taylor Brian D.
Published: October 2007

Smart card technologies offer public transit agencies unprecedented opportunity to price services flexibly by time, distance, and mode and in conjunction with neighboring transit operators. They also can simplify boarding, streamline accounting, and provide better passenger data. Some transit systems have moved quickly to adopt smart card fare media, others are moving more cautiously, and still others eschew smart cards—at least for now. Why such differences? U.S. transit agencies were surveyed to gauge current levels of interest in smart card technologies as next-generation fare media; examine knowledge and perceptions of costs, benefits, and risks of smart card adoption; and determine the status of system implementation, the degree of planning toward implementation, and the levels of participation in interagency collaboration to realize interoperability. Factors common to agencies that have and have not adopted smart card technology also were examined. Results indicate that the consideration and adoption of smart card technologies and interoperable systems vary by funding availability and partnerships with other operators in joint projects for intelligent transportation systems. Perceptions of benefits, costs, and risks of such technologies also vary by status of smart card system planning and implementation. Managers often are uncertain about the costs in general and the benefits in particular of such a move, especially regarding interoperable systems. History predicts the future: technologically sophisticated operators tend to embrace smart cards, whereas those working collaboratively with other transit agencies are most likely to adopt interoperable systems.
City CarShare
Authors: Cervero Robert , Golub Aaron , Nee Brendan
Published: October 2007

Four years after the introduction of City CarShare in the San Francisco, Bay area in California, 29% of carshare members had gotten rid of one or more cars, and 4.8% of members’ trips and 5.4% of their vehicle miles traveled were in carshare vehicles. Matched-pair comparisons with a statistical control group suggest that, over time, members have reduced total vehicular travel. However, most declines occurred during the first 1 to 2 years of the program; 3 to 4 years after City CarShare's inauguration, earlier declines had leveled off. Because many carshare vehicles are small and fuel-efficient but can carry several people, the trend in per capita gasoline consumption also is downward. Mindful of the cumulative costs of driving, carshare members appear to have become more judicious and selective when deciding whether to drive, take public transit, walk, bike, or even forgo a trip. Coupled with reduced personal car ownership, these factors have given rise to a resourceful form of automobility in the San Francisco Bay area.
Growth in Worldwide Carsharing
Authors: Shaheen Susan A. , Cohen Adam P.
Published: October 2007

Carsharing (or short-term auto use) provides a flexible alternative that meets diverse transportation needs across the globe while reducing the negative impacts of private vehicle ownership. Although carsharing appeared in Europe between the 1940s and 1980s, the concept did not become popularized until the early 1990s. For nearly 20 years, worldwide participation in carsharing has been growing. Today, carsharing operates in approximately 600 cities around the world, in 18 nations and on 4 continents. Approximately 348,000 individuals share nearly 11,700 vehicles as part of organized carsharing services (>60% in Europe). Malaysia is operating a carsharing pilot, with a planned launch in 2007. Another eight countries are exploring carsharing. Thirty-three carsharing expert surveys were identified on an international basis. Cost savings, convenient locations, and guaranteed parking were identified as the most common motivations for carsharing use worldwide. An international comparison of carsharing operations, including similarities and differences, is provided. Continued growth is forecast, particularly among new and emerging market segments, such as businesses and universities. Growth-oriented operators will continue to account for the largest number of members and fleets deployed worldwide. In addition, high energy costs; limited and expensive parking; ongoing diffusion of operational knowledge, benefits, and supportive technologies; and increased demand for personal vehicle access in developing nations will affect carsharing's growth and expansion.
Another Look at FTA-Approved Sampling Plans for Fixed-Route Bus Services
Authors: Chu Xuehao
Published: October 2007

The Federal Transit Administration has approved six sampling plans that transit agencies can use to estimate the consumption of fixed-route bus services for reporting to the National Transit Database. These sampling plans follow a simple framework and are assumed to be universally applicable. Some background information is presented, and then these sampling plans (including the related statistical theory, the development of the sampling plans based on this theory, and the estimation procedure) are reviewed. More important, a set of allowable variations in passenger miles is defined for each sampling plan, and it is demonstrated that these sampling plans are not universally applicable. Improved sampling options are proposed within the simple framework of the original sampling plans.
Stripping Analysis
Authors: Wang Joseph
Published: October 2007

The sections in this article are

Introduction

Anodic Stripping Voltammetry

Principles

Interferences

Stripping Potentiometry

Adsorptive Stripping Voltammetry

Practical Considerations

Electrodes

Cells and Instrumentation

Representative Examples
Inorganic Nanoparticles with Fullerene‐like Structure and Nanotubes; Some Electrochemical and Photoelectrochemical Aspects
Authors: Tenne Reshef
Published: October 2007

The sections in this article are

Introduction

Classification of the Different Mechanisms for the Folding of Inorganic Compounds, which Yield Close‐cage Structures and Nanotubes

Synthesis of Inorganic Nanotubes and Fullerene‐like Nanoparticles

Thermodynamic, Structural, and Topological Considerations

Physical Properties

Band Structure Calculations

Optical Studies in the
UV
and Visible

R
aman Spectroscopy

Mechanical Properties

Electrochemistry and Photoelectrochemistry Using
IF
‐Materials and Inorganic Nanotubes

Electrodeposition of
IF
‐
MS
2
(M = W,Mo)Nanoparticles and their Photoelectrochemical Properties

Electrochemical Studies with
V
2
O
5
and Metallic Nanotubes

Applications

Conclusion

Acknowledgment
Fullerenes
Authors: Echegoyen Lourdes E. , Ángeles Herranz M. , Echegoyen Luis
Published: October 2007

The sections in this article are

Introduction

Electrochemistry of
C
60
and
C
70

Reduction of
C
60

Reduction of
C
70

Oxidation of
C
60
and
C
70

Electrochemistry of the Higher Fullerenes,
C
76
,
C
78
,
C
82
, and
C
84

Reduction and Oxidation of
C
76

Reduction and Oxidation of
C
78

Reduction and Oxidation of
C
82

Reduction and Oxidation of
C
84

Electrochemistry of
C
60
Derivatives

Singly Bonded Functionalized Derivatives of
C
60

Hydrofullerenes

Alkylfullerenes

Fluorofullerenes

Other Singly Bonded Derivatives

Cycloaddition Products

C
60
Electron‐acceptor Cycloadducts

C
60
‐Electron Donor Cycloadducts

Cyclopropanated Derivatives of
C
60

C
‐bridged Cyclopropanated Derivatives: Methanofullerenes and Fulleroids

Other Cyclopropanated Derivatives of
C
60

C
60
‐dimers

Electrochemistry of
C
70
Derivatives

Electrochemistry of
C
76
,
C
78
, and
C
84
Derivatives

Electrosynthesis

Electrosynthesis of
C
60
and
C
70
Derivatives

Electrochemically Induced Retro‐cyclopropanation Reactions
Green Light for the Future
Authors: Wylie L. , Grieve K.
Published: October 2007

Materials science is a key research area for the development of technologies needed to address the energy and environmental challenges facing our society. Since it began, Advanced Functional Materials has been publishing key papers in materials for energy production and storage. Here, two of the editors highlight areas of special prominence and discuss the way the journal is improving its services.
Cover Picture: High Definition Digital Fabrication of Active Organic Devices by Molecular Jet Printing (Adv. Funct. Mater. 15/2007)
Authors: Chen J. , Leblanc V. , Kang S. H. , Benning P. J. , Schut D. , Baldo M. A. , Schmidt M. A. , Bulović V.
Published: October 2007

A new method for direct patterning of organic optoelectronic/electronic devices using a reconfigurable and scalable printing method is reported by Vladimir Bulovic and co‐workers on p. 2722. The printing technique is applied to the fabrication of high‐resolution printed organic light emitting devices (OLEDs) and organic field effect transistors (OFETs). Remarkably, the final print‐deposited films are evaporated onto the substrate (rather than solvent printed), giving high‐quality, solvent‐free, molecularly flat structures that match the performance of comparable high‐performance unpatterned films.

We introduce a high resolution molecular jet (MoJet) printing technique for vacuum deposition of evaporated thin films and apply it to fabrication of 30 μm pixelated (800 ppi) molecular organic light emitting devices (OLEDs) based on aluminum tris(8‐hydroxyquinoline) (Alq3) and fabrication of narrow channel (15 μm) organic field effect transistors (OFETs) with pentacene channel and silver contacts. Patterned printing of both organic and metal films is demonstrated, with the operating properties of MoJet‐printed OLEDs and OFETs shown to be comparable to the performance of devices fabricated by conventional evaporative deposition through a metal stencil. We show that the MoJet printing technique is reconfigurable for digital fabrication of arbitrary patterns with multiple material sets and high print accuracy (of better than 5 μm), and scalable to fabrication on large area substrates. Analogous to the concept of “drop‐on‐demand” in Inkjet printing technology, MoJet printing is a “flux‐on‐demand” process and we show it capable of fabricating multi‐layer stacked film structures, as needed for engineered organic devices.
Inside Front Cover: One‐Pot Synthesis and Hierarchical Assembly of Hollow Cu2O Microspheres with Nanocrystals‐Composed Porous Multishell and Their Gas‐Sensing Properties (Adv. Funct. Mater. 15/2007)
Authors: Zhang H. , Zhu Q. , Zhang Y. , Wang Y. , Zhao L. , Yu B.
Published: October 2007

On p. 2766, Qinshan Zhu and co‐workers report on multishell hollow Cu2O microspheres that are synthesized by a facile and one‐pot solvothermal route. A two‐step organization process, in which hollow microspheres of Cu2(OH)3NO3 are formed first followed by reduction to Cu2O by glutamic acid, leads to the special multishell and hollow microstructures. Interestingly, a Cu2O gas sensor fabricated with the multishell microspheres shows a much higher sensitivity to ethanol than solid Cu2O microspheres.

Hierarchical assembly of hollow microstructures is of great scientific and practical value and remains a great challenge. This paper presents a facile and one‐pot synthesis of Cu2O microspheres with multilayered and porous shells, which were organized by nanocrystals. The time‐dependent experiments revealed a two‐step organization process, in which hollow microspheres of Cu2(OH)3NO3 were formed first due to the Ostwald ripening and then reduced by glutamic acid, the resultant Cu2O nanocrystals were deposited on the hollow intermediate microspheres and organized into finally multishell structures. The special microstructures actually recorded the evolution process of materials morphologies and microstructures in space and time scales, implying an intermediate‐templating route, which is important for understanding and fabricating complex architectures. The Cu2O microspheres obtained were used to fabricate a gas sensor, which showed much higher sensitivity than solid Cu2O microspheres.
Unprecedented Effects of Additives and Ligand‐to‐Metal Ratio on the Enantiofacial Selection of Copper‐Catalyzed Alkynylation of α‐Imino Ester with Arylacetylenes
Authors: Shao Zhihui , Wang Jun , Ding Kai , Chan Albert S. C.
Published: October 2007

The first catalytic asymmetric addition of arylacetylenes to α‐imino esters was carried out using chiral copper(I) complexes as catalysts under mild reaction conditions, providing the corresponding alkynylation products in good yields with 67–74 % ee values. Profound effects of the ligand‐to‐metal ratio and additives on the stereofacial selection were observed. Both enantiomers of a given product can be obtained with almost identical enantiomeric excess using the same chiral ligand by adjusting the ligand‐to‐metal ratio.
Abnormal T‐cell reactivities in childhood inflammatory demyelinating disease and type 1 diabetes
Authors: Banwell Brenda , Bar‐Or Amit , Cheung Roy , Kennedy Julia , Krupp Lauren B. , Becker Dorothy J. , Dosch Hans‐Michael
Published: October 2007

Objectives

Pediatric‐onset multiple sclerosis offers a unique window into early targets and mechanisms of immune dysregulation. It is unknown whether heightened T‐cell reactivities documented in adult patients, to both target‐organ and environmental antigens, emerge in parallel or develop as early or late events. Our objectives were to determine the presence, pattern, and specificity of abnormal T‐cell reactivities to such antigens in the earliest stages of the multiple sclerosis process.

Methods

Peripheral T‐cell proliferative responses to self‐, dietary, and control antigens were blindly evaluated in a large cohort of well‐characterized children (n = 172) with central nervous system (CNS) inflammatory demyelination (n = 63), recent‐onset type 1 (insulin‐dependent) diabetes mellitus (T1D; n = 41), nonautoimmune neurological conditions (n = 39), and healthy children (n = 29).

Results

Children with inflammatory demyelination, CNS injury, and T1D exhibited heightened T‐cell reactivities to self‐antigens, and these responses were not strictly limited to the disease target organs. Children with autoimmune disease and CNS injury also exhibited abnormal T‐cell responses against multiple cow‐milk proteins. Responses to specific milk epitopes distinguished T1D from inflammatory demyelination and other neurological diseases.

Interpretation

Abnormal T‐cell reactivities to self‐ and environmental antigens manifest in the earliest clinical stages of inflammatory demyelination and T1D. The pattern of heightened T‐cell reactivities implicates both shared and distinct mechanisms of immune dysregulation in the different autoimmune diseases. Abnormal T‐cell responses in children with tissue injury challenge the prevailing view that CNS autoreactive cells inherently mediate the disease in early multiple sclerosis. Ann Neurol 2007
Application of palladacycle catalyst in the synthesis of mono‐arylpyridyl bromides
Authors: Zhang Jinli , Wu Yangjie , Zhu ZhiWu , Ren Gerui , Mak Thomas C. W. , Song Maoping
Published: October 2007

The mono‐arylpyridyl bromides are very useful key intermediates that can be further functionalized to generate bioactive compounds. It is possible to obtain mono‐arylation products of 3,5‐dibromopyridine with high preferentiality and high yields by air‐ and moisture‐stable palladacycle (catalyst II) catalyzed Suzuki reaction of 3,5‐dibromopyridine with a series of arylboronic acids—ester under the conditions of K2CO3–toluene–methanol (4:1, v/v), reflux (75 °C), 5.6 equiv. of 3,5‐dibromopyridine with the ratio (mono:bis) ranging from of 99:1 to 90:10. This new method could also be used to easily achieve pyridylpyridyl bond formation to afford 3‐bromo‐5‐pyridylpyridine (3j). Copyright © 2007 John Wiley & Sons, Ltd.
An easy way to achieve three‐dimensional metal–organic coordination polymers: synthesis and crystal structure of dizinc diisophthalate bis‐dimethylsulfoxide monohydrate: [Zn2(ip)4(DMSO)2(H2O)·3 DMSO]n
Authors: Zevaco Thomas A. , Männle Daniel , Walter Olaf , Dinjus Eckhard
Published: October 2007

An easy way of producing three‐dimensional metal–organic coordination polymers involving zinc(II) benzene‐dicarboxylates is reported. The reaction of zinc oxide with benzene dicarboxylic acids in water yielded the expected hydrated zinc dicarboxylates. These zinc compounds were then suspended in dimethylsulfoxide and heated to above 100 °C for a couple of hours; the solutions were allowed after filtration to cool down to eventually deliver crystalline compounds displaying complex zeotype structures. The crystal structure of the title compound, [Zn2(ip)4(DMSO)2(H2O)·3 DMSO]n (ipH2 = isophthalic acid = 1,3‐benzenedicarboxylic acid, DMSO = dimethylsulfoxide), is reported for the first time and shows a three‐dimensional network where octahedrally and tetrahedrally coordinated zinc atoms (present in a 1:1 ratio) are linked by bridging isophthalate ligands. The complex coordination network exhibits a remarkable channel structure along the z‐axis. The related zinc terephthalate–DMSO complex was similarly prepared and the crystal structure determination revealed an already documented zeotypic structure: [{Zn4(OH)2(tp)3(DMSO)4} 2H2O]n (tpH2 = terephthalic acid = 1,4‐benzenedicarboxylic acid). Weak interactions as well as hydrogen bonds involving water molecules and carboxy groups play a major role in the formation of these complex three‐dimensional networks. In comparison, the zinc 1,2‐benzene‐dicarboxylate–DMSO complex could not be isolated, even under more drastic conditions. The higher symmetry of the coordination network found in the zinc terephthalate–DMSO complexes was incidentally corroborated by 13C CP/MAS spectroscopy. Copyright © 2007 John Wiley & Sons, Ltd.
Hydraulic characteristics of aerobic granules using size exclusion chromatography
Authors: Adav Sunil S. , Chang Cheng‐Hsuan , Lee Duu‐Jong
Published: October 2007

Elution of poly(ethylene glycol) of molecular weight 200–20,000 Da from a size exclusion chromatography column packed with phenol‐fed aerobic granules of three different nominal sizes (types I–III) has been investigated. The pore sizes of the three types of granules were evaluated based on the mean hydraulic times of the elution curves that decreased directly proportional to the increased logarithm of the molecular mass of a standard tracer and increased as granule size decreased. The corresponding exclusion limits for types I–III granules were 139,000, 123,000, and 54,500 Da, respectively. A one‐dimensional convection–dispersion model described the effective dispersion coefficients of the tracers through the granule column. The intra‐granular permeabilities and convective and diffusional transit times through the granule interior were evaluated by a dual porosity model. For small molecules of molecular mass <5,000 Da, intra‐granular convection dominated transport mechanisms at fast moving velocity. For comparatively larger molecules, diffusion barrier existed to limit nutrient supply to the granules. The size exclusion test provided intra granular transport characteristics using detailed analysis on the elution data. Biotechnol. Bioeng. 2008;99: 791–799. © 2007 Wiley Periodicals, Inc.
Genomic and proteomic exploration of CHO and hybridoma cells under sodium butyrate treatment
Authors: Yee Joon Chong , de Leon Gatti Marcela , Philp Robin J. , Yap Miranda , Hu Wei‐Shou
Published: October 2007

Sodium butyrate has been known to increase the specific productivity of recombinant proteins in mammalian cells. In quest of physiological mechanisms leading to the increased productivity, DNA microarray and two dimensional gel electrophoresis (2DE) were used to assess the response of Chinese hamster ovary (CHO) and a mouse hybridoma cell (MAK) to butyrate treatment at the transcriptome and proteome level. The expression of the orthologous genes represented on both CHO cDNA and mouse Affymetrix microarray, as well as genes in the same ontological class were compared. Only a relatively small number of orthologs changed their expression consistently between the two cell lines, however, at a functional class level many genes involved in cell cycle and apoptosis were affected in both cell lines. Furthermore, a large number of genes involved in protein processing, secretion and redox activity were upregulated in both CHO and MAK cells. More genes showed a consistent trend of change at both transcript and protein levels than those which showed opposite trend in MAK cells. Overall the results suggested that the changes arising in the protein processing machinery may be responsible for the increased productivity upon butyrate treatment in both CHO and MAK cells. Biotechnol. Bioeng. 2008;99: 1186–1204. © 2007 Wiley Periodicals, Inc.
Modeling of a foamed emulsion bioreactor: I. Model development and experimental validation
Authors: Kan Eunsung , Deshusses Marc A.
Published: October 2007

Recently, a new type of bioreactor for air pollution control referred to as the foamed emulsion bioreactor (FEBR) has been developed. The process relies on the emulsion of an organic phase with a suspension of an actively growing culture of pollutant‐degrading microorganisms, made into a foam with the air undergoing treatment. In the current paper, a diffusion and reaction model of the FEBR is presented and discussed. The model considers the fate of the volatile pollutant in the emulsion that constitutes the liquid films of the FEBR. Oxygen limitation as well as substrate inhibition were included in the biokinetic relationships. The removal of toluene vapors served for the validation of the model. All the model parameters were determined by independent experiments or taken from the literature. The model predictions were found to be in good agreement with the experimental data and the model provided useful insights on the phenomena occurring in the FEBR. Model parametric sensitivity studies and further discussion of the factors that limit the performance of the FEBR are presented in Part 2 of this paper. Biotechnol. Bioeng. 2008;99: 1096–1106. © 2007 Wiley Periodicals, Inc.
Characterization of spatial growth and distribution of chondrocyte cells embedded in collagen gels through a stereoscopic cell imaging system
Authors: Kino‐oka Masahiro , Maeda Yoshikatsu , Sato Yasuaki , Khoshfetrat Ali Baradar , Yamamoto Takeyuki , Sugawara Katsura , Taya Masahito
Published: October 2007

The stereoscopic image analysis of fluorescence‐labeled chondrocyte cells for cytoplasm and nucleus was performed for the quantitative determination of spatial cell distribution as well as cell aggregate size in the collagen‐embedded culture. The three‐dimensional histomorphometric data indicated that the cells in the gels formed aggregates by cell division, and the size of aggregates increased with elapsed culture time. In the culture seeded at 2.0 × 106 cells/cm3, the cells showed a semilunar shape that is a typical chondrocytic morphology, and formed the dense cell aggregates producing collagen type II. From the quantitative analysis of aggregate size, in addition, it was found that the cell division caused the aggregate growth with an increase of cell number in respective aggregates at 7 days, and some of aggregates made coalescence at 14 days. In the gel surface region, further coalescence of aggregates accompanied with cell division produced larger cell clusters, creating cell layers on the gel surface at the end of culture (21 days). In the culture seeded at 2.0 × 105 cells/cm3, the different manner of aggregation was observed. At 14 days, the loose clusters of spindle‐shaped cells emerged in the deeper region of gels, suggesting that the cell migration and gathering occurred in the gels. This loose‐clustered aggregates did not produce collagen type II. Our results suggest that the seeding density is a factor to cause different mechanisms of cell distribution accompanied with the formation of aggregates as well as collagen type II. Biotechnol. Bioeng. 2008;99: 1230–1240. © 2007 Wiley Periodicals, Inc.
Impact of tumor‐specific targeting and dosing schedule on tumor growth inhibition after intravenous administration of siRNA‐containing nanoparticles
Authors: Bartlett Derek W. , Davis Mark E.
Published: October 2007

This study addresses issues of relevance for siRNA nanoparticle delivery by investigating the functional impact of tumor‐specific targeting and dosing schedule. The investigations are performed using an experimental system involving a syngeneic mouse cancer model and a theoretical system based on our previously described mathematical model of siRNA delivery and function. A/J mice bearing subcutaneous Neuro2A tumors ∼100 mm3 in size were treated by intravenous injection with siRNA‐containing nanoparticles formed with cyclodextrin‐containing polycations (CDP). Three consecutive daily doses of transferrin (Tf)‐targeted nanoparticles carrying 2.5 mg/kg of two different siRNA sequences targeting ribonucleotide reductase subunit M2 (RRM2) slowed tumor growth, whereas non‐targeted nanoparticles were significantly less effective when given at the same dose. Furthermore, administration of the three doses on consecutive days or every 3 days did not lead to statistically significant differences in tumor growth delay. Mathematical model calculations of siRNA‐mediated target protein knockdown and tumor growth inhibition are used to elucidate possible mechanisms to explain the observed effects and to provide guidelines for designing more effective siRNA‐based treatment regimens regardless of delivery methodology and tumor type. Biotechnol. Bioeng. 2008; 99; 975–985. © 2007 Wiley Periodicals, Inc.
Growth and cometabolic reduction kinetics of a uranium‐ and sulfate‐reducing Desulfovibrio/Clostridia mixed culture: Temperature effects
Authors: Boonchayaanant Benjaporn , Kitanidis Peter K. , Criddle Craig S.
Published: October 2007

Bioremediation of contaminated soils and aquifers is subject to spatial and temporal temperature changes that can alter the kinetics of key microbial processes. This study quantifies temperature effects on the kinetics of an ethanol‐fed sulfate‐reducing mixed culture derived from a uranium‐contaminated aquifer subject to seasonal temperature fluctuations. The mixed culture contains Desulfovibrio sp. and a Clostridia‐like organism. Rates of growth, ethanol utilization, decay, and uranium reduction decreased with decreasing temperature. No significant uranium reduction was observed at 10°C. While both Monod saturation kinetics and pseudo second‐order kinetics adequately described the rates of growth and utilization of electron donor (ethanol), model parameters for the pseudo second‐order expression had smaller uncertainties. Uranium reduction kinetics were best described by pseudo second‐order kinetics modified to include a term for inactivation/death of cells. Biotechnol. Bioeng. 2008;99: 1107–1119. © 2007 Wiley Periodicals, Inc.
The impact of manual processing on the expansion and directed differentiation of embryonic stem cells
Authors: Veraitch Farlan S. , Scott Rosario , Wong Ju‐Wei , Lye Gary J. , Mason Chris
Published: October 2007

Embryonic stem cells (ESC) have the developmental potential to form every adult cell type, even after prolonged culture. Reproducibly culturing pluripotent populations and directing differentiation has proven technically challenging yet will underpin the provision of stem cells for both screening and therapeutic applications. This study investigated whether the variations inherent in manual handling procedures cause inconsistent proliferation and phenotypic variability. Two mouse ESC green fluorescent protein (GFP) reporter cells lines, Oct4‐GiP and 46C, were used to assess Oct4 expression during expansion and Sox1 expression during directed neuroectoderm differentiation. High inoculation cell densities (ICD) had a negative impact on Oct4‐GFP expression. Similarly, increasing ICD caused a drop in Sox1‐GFP expression in differentiating cultures. The expansion process had an optimum ICD of 31,800 cells cm−2 whilst the highest yield of Sox1‐GFP positive cells were found at an ICD of 16,400 cells cm−2. These results implicate variable cell density as a major cause of interindividual variability. Passaging exposes cells to dynamic and repeated changes in their micro‐environment. This was associated with a rapid drop in temperature and rise in pH. Extended exposure of 1, 2 and 3 h to ambient conditions resulted in the inhibition of ESC proliferation and Oct4‐GFP expression. Dissociation subjects cells to fluid flow and centrifugal forces. Repeated exposure to fluid flow in capillaries prior to cultivation reduced the proliferative capacity of undifferentiated ESCs and caused a significant drop in differentiated neuroectoderm yield. Excessive centrifugal forces up to 1,000g caused shifts in phenotype and proliferation during expansion and differentiation. These studies highlight the need for automated cultivation systems which reproducibly control cell density, fluid flow, centrifugal forces, pH and temperature for the dissociation and inoculation of ESC processes. Biotechnol. Bioeng. 2008;99: 1216–1229. © 2007 Wiley Periodicals, Inc.
Fenestrated endovascular repair for juxtarenal aortic aneurysm
Authors: Scurr J R H , Brennan J A , Gilling-Smith G L , Harris P L , Vallabhaneni S R , McWilliams R G
Published: October 2007

Background

The outcome of fenestrated endovascular aneurysm repair (F-EVAR) was evaluated.

Methods

Between February 2003 and December 2006, 45 patients (median age 73 (range 53–85) years) underwent primary (41) or secondary (four) F-EVAR for an abdominal aortic aneurysm with infrarenal neck anatomy unsuitable for a standard stent-graft. Median aneurysm diameter was 68 (range 55–100) mm and median infrarenal aortic neck length was 6 (range 0–13) mm. Customized fenestrated Zenith® stent-grafts were employed in all procedures, incorporating fenestrations to preserve flow into renal (80), superior mesenteric (35) and coeliac (two) arteries. Eighty-two target vessels were stented (61 bare metal, 21 covered).

Results

All aneurysms were isolated successfully, with preservation of the target vessels. One accessory renal artery was lost. One patient died after 5 days from myocardial infarction, and another at 3 months from multiorgan failure secondary to atheroembolism. At median follow-up of 24 (range 1–48) months, all aneurysms were stable or shrinking, with no late ruptures or graft-related endoleaks. Six patients required a secondary intervention. The primary vessel patency rate was 96·6 per cent. There were four late deaths, unrelated to the aneurysm.

Conclusion

F-EVAR enabled successful treatment of juxtarenal aortic aneurysm with a low complication rate.
Assessment of a patient consultation questionnaire-based scoring system for stratification of outpatient risk of colorectal cancer
Authors: Rai S , Ballal M , Thomas W M , Miller A S , Jameson J S , Steward W P
Published: October 2007

Background

The UK government's fast-track 2-week wait (2WW) rule and colorectal cancer guidelines aimed to detect patients at high risk of having colorectal cancer, but the yield has been poor. A patient consultation questionnaire (PCQ)-based scoring system may be an effective tool for prioritizing colorectal referrals. The aim of this study was to validate the system in a large and ethnically diverse population and to compare it with 2WW referrals.

Methods

Over a 1-year period, all colorectal referrals (2WW and traditional letters) at nine hospitals in Leicestershire were sent a PCQ to complete and return. A weighted numerical score (WNS), which reflects the patient's risk of having colorectal cancer, was calculated and compared with the hospital diagnosis.

Results

Of a total of 1422 PCQs returned, 83 patients were diagnosed with colorectal cancer. The 2WW referrals constituted 35·7 per cent of all referrals. The mean WNS of patients with colorectal cancer was significantly higher than that of the other patients (mean 76·3 versus 48·9 respectively; P < 0·001). For similar cancer detection rates (or sensitivity), the specificity of a WNS cut-off of 70 was significantly better than that of the 2WW system (82·7 versus 66·1 per cent; P < 0·001).

Conclusion

The PCQ-based WNS system improves specificity for detecting colorectal cancer, particularly when the WNS exceeds 70.
Rescue inverse crush: A way of get out of trouble
Authors: Furuichi Shinichi , Airoldi Flavio , Colombo Antonio
Published: October 2007

This report describes a technique for bailout stenting in treating coronary bifurcation lesion when the side branch (SB) is compromised after stent implantation in the main branch (MB) and there are difficulties to negotiate the guidewire from the MB into the true lumen of a dissection of the SB. © 2007 Wiley‐Liss, Inc.
The impact of chronically diseased coronary arteries and stenting on the corrected TIMI frame count in elective coronary angiography and percutaneous coronary intervention procedures
Authors: Vijayalakshmi Kunadian , Kunadian Babu , Whittaker Victoria J. , Williams David , Wright Robert A. , Sutton Andrew GC , Hall James A. , de Belder Mark A.
Published: October 2007

The impact of chronic coronary obstructions on resting blood flow in stable cardiac patients and the response to percutaneous coronary intervention (PCI) using the TIMI frame count method has not been well documented. We studied the impact of coronary artery stenosis severity on the corrected TIMI frame count (cTFC) in chronically stenosed coronary arteries. We prospectively and quantitatively determined the impact of stenting on the cTFC during elective PCI. Methods: In substudy 1, analysis was performed to obtain the mean cTFC for arteries with <50% stenosis (Group A), 51–75% stenosis (Group B), 76–85% stenosis (Group C1), 86–95% stenosis (Group C2) and 96–99% stenosis (Group C3). In substudy 2, the cTFC and quantitative coronary angiography were performed pre‐ and post‐PCI. Results: In substudy 1, the cTFC increased exponentially beyond a diameter stenosis of 75% (P < 0.01). However there was no significant difference in the cTFC for coronary arteries with <75% stenosis. In substudy 2, the overall pre‐ and poststenting cTFC was 17.1 ± 11.7 and 7.8 ± 2.7 (P < 0.01) and the TFC index [calculated by dividing the mean cTFC for the relevant artery by the mean cTFC for the corresponding coronary artery in a previously derived control group in our laboratory] was 1.6 ± 1 and 0.7 ± 0.2 (P = < 0.01), respectively. Conclusion: We have demonstrated that there was a significant increase in the cTFC when the coronary artery stenosis was more than 75% reflecting significant flow abnormalities at this degree of stenosis in chronically diseased coronary arteries. Following stenting there is a significant improvement in the cTFC, which is better than the cTFC for arteries with normal flow, suggesting early hyperaemia. © 2007 Wiley‐Liss, Inc.
Patients' skin dose during percutaneous coronary intervention for chronic total occlusion
Authors: Suzuki Shigeru , Furui Shigeru , Isshiki Takaaki , Kozuma Ken , Koyama Yutaka , Yamamoto Hiroyuki , Ochiai Masahiko , Asakura Yasushi , Ikari Yuji
Published: October 2007

Objectives:

The purpose of this research is to assess the patient's entrance skin dose (ESD) during percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) in six institutions.

Background:

Only a few reports are available on the patients' exposure during the procedures.

Methods:

This study was approved by all of the six institutional review boards, and all patients gave informed consent. This study included consecutive 72 patients who underwent PCI procedures for CTO in the six institutions. They wore jackets that had 100 radiosensitive indicators adhered to the back during the PCI procedures. The patients' ESDs were calculated from the color difference of the indicators. The total fluoroscopic time, total number of cine frames, and maximal ESD were compared among institutions. To check for effects on the skin, clinical follow‐up was performed at 1–2 days, 2 weeks, and 3 months after the PCI procedure.

Results:

The total fluoroscopic time was 45.0 ± 24.5 min (range: 10.3–113.0 min) and the total number of cine frames was 4,558 ± 3,440 (range: 855–22,950). The maximum ESD for each patient was 3.2 ± 2.1 Gy (range: 0.5–10.2 Gy, median: 2.7 Gy). The average maximum ESDs were significantly different among institutions (P = 0.0006), and they were 1.6–5.3 Gy. Radiation skin injuries were observed in 2 patients.

Conclusions:

The maximum ESDs during PCI for CTO exceed the thresholds for radiation skin injuries in many cases, although there are differences in the average maximum ESDs among institutions. © 2008 Wiley‐Liss, Inc.
Stenting for superior vena cava obstruction in pediatric heart transplant recipients
Authors: Sachdeva Ritu , Seib Paul M. , Burns Samuel A. , Fontenot Eudice E. , Frazier Elizabeth A.
Published: October 2007

Background:

Superior vena cava (SVC) obstruction can be a complication in heart transplant recipients. We reviewed our experience with relief of SVC obstruction using endovascular stents in pediatric heart transplant recipients.

Methods:

Study cohort included pediatric heart transplant recipients, followed at our institution, who required endovascular stent placement for SVC obstruction. Data retrieved retrospectively included cardiac diagnosis, age, and weight at transplant, surgical technique of transplant (bicaval vs. biatrial anastomosis), previous cardiovascular surgeries, presenting symptoms, date of SVC stent placement, and need for reintervention.

Results:

From March 1990 to June 2006, 5.1% (7/138) pediatric heart transplant recipients who were followed at our institution had SVC obstruction requiring stent placement. Median age and weight at transplant was 9 months and 8.7 kg, respectively. Four patients previously had a cavopulmonary anastomosis. Transplant surgery involved bicaval anastomosis in 6 and biatrial in 1. Of the 7 patients included in the study, 2 were asymptomatic, 2 were symptomatic (1 with chylothorax, 1 with headache), and 3 were identified at the time of transplant surgery. Median time from transplant surgery to SVC stent placement was 2 months (0–14 months). Three patients required reintervention as redilation of SVC stent (n = 1) or additional SVC stent (n = 2). In one patient the stent migrated to the pulmonary artery but was retrieved.

Conclusion:

SVC obstruction can be an important complication following heart transplantation, especially in infants with previous cavopulmonary anastomosis, undergoing heart transplant using bicaval technique. SVC obstruction can be safely and effectively treated using endovascular stents. © 2007 Wiley‐Liss, Inc.
Enantioselective Nickel‐Catalyzed Cross‐Coupling Reactions of Trialkynylindium Reagents with Racemic Secondary Benzyl Bromides
Authors: Caeiro Jorge , Pérez Sestelo José , Sarandeses Luis A.
Published: October 2007

The first enantioselective sp–sp3 cross‐coupling reaction between alkynyl organometals and racemic benzyl bromides is reported. The coupling is performed at room temperature by using NiBr2⋅diglyme and (S)‐(iPr)‐Pybox as the catalytic system and trialkynylindium reagents as nucleophiles. The reaction is stereoconvergent, both enantiomers of the racemic benzyl bromide are converted into one enantiomer of the product, and stereospecific. The reaction takes place efficiently in good yields and with high atom economy, as the triorganoindium reagents transfer the three organic groups attached to indium (only 40 mol % of R3In is used).
Highly Enantioselective Approach to Geminal Bisphosphonates by Organocatalyzed Michael‐Type Addition of β‐Ketoesters
Authors: Capuzzi Marinella , Perdicchia Dario , Jørgensen Karl Anker
Published: October 2007

A valuable organocatalyzed protocol has been developed for the asymmetric synthesis of bisphosphonate derivatives, a class of pharmaceutically important molecules. Cheap and commercially available dihydroquinine effectively catalyzed conjugate additions of cyclic β‐ketoesters to ethylidenebisphosphonate esters, leading to optically active geminal bisphosphonates, bearing an all‐carbon substituted quaternary stereocenter, in high yields and enantioselectivities of up to 99 % ee. Further elaborations of Michael adducts to the corresponding bisphosphonic acids or vinyl phosphonates have also been successfully performed, with conservation of optical purity.