bluuebunny/crossref_metadata_2025 huggingface dataset:
RAFT‐Based Synthesis and Characterization of ABC versus ACB Triblock Copolymers Containing tert‐Butyl Acrylate, Isoprene, and Styrene Blocks
Authors: Germack David S. , Wooley Karen L.
Published: October 2007

The syntheses of the ABC and ACB triblock copolymer topological isomers poly(tert‐butyl acrylate)‐block‐polyisoprene‐block‐polystyrene (ABC) and poly(tert‐butyl acrylate)‐block‐polystyrene‐block‐polyisoprene (ACB) using the RAFT‐controlled radical polymerization method are described. The triblock copolymers were isolated with molecular weights on the order of 20 000 Da and molecular weight distributions of 1.3–1.5. The polymers described herein demonstrated thermal decompositions at 200 °C, characteristic of tert‐butyl esters, and their structure and composition were confirmed by a combination of infrared, 1H, and 13C NMR spectroscopies.

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Single and Double Polymer Layer Arrangements of Acid Groups Containing Cellulose and Basic Groups Containing Polyethyleneimine on Steel
Authors: Plagge Andreas , Adler Hans‐Juergen , Jaehne Evelyn , Paliwoda Grazyna , Rohwerder Michael , Stratmann Martin , Eichhorn Klaus‐Jochen
Published: October 2007

This paper presents the first results of a project aimed at investigating the arrangement of polyelectrolyte layers on unalloyed steel. We studied the structure of double and single polymer layers consisting of cellulose phosphate (HP‐PP‐C) and polyethyleneimine (PEI). Layers were characterized by variable angle ellipsometry, AFM and XPS. In particular, XPS indicated the incorporation of iron ions into cellulose phosphate layers, but, in contrast, these ions could not be observed in PEI layers. Results indicated that the homogeneity and qualitative corrosion performance of double layers (HP‐PP‐C/PEI) on unalloyed steel depend on the deposition of cellulose phosphate at the interface with steel.

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Nitroxide‐Mediated Radical Polymerization in Microemulsion
Authors: Wakamatsu Junpei , Kawasaki Masahiro , Zetterlund Per B. , Okubo Masayoshi
Published: October 2007

Nitroxide‐mediated polymerizations of styrene in microemulsion have been carried out at 125 °C using the cationic surfactant tetradecyltrimethylammonium bromide and the nitroxides 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (TEMPO) and N‐tert‐butyl‐N‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)] nitroxide (SG1). TEMPO‐mediated polymerizations were extremely slow, with large particles (dn = 39–129 nm) and broad molecular weight distributions (MWDs). The origin of the broad MWDs was likely significant alkoxyamine decomposition and differing diffusion rates of monomer and low MW alkoxyamines (and nitroxide) between monomer‐swollen micelles and polymer particles. SG1‐mediated polymerizations proceeded at higher rates, resulting in nanoparticles (dn = 21–37 nm) and lower $\overline M _{\rm w} /\overline M _{\rm n}$ than for TEMPO.

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Information retrieval in medicine: The electronic medical record as a new domain
Authors: Smith Catherine Arnott
Published: November 2007

“The medical record is a material form of public memory,” Berg (1996) writes, “a structured distributing and collecting device, where all tasks concerning a patient's trajectory must begin and end…;” [Italics original; p. 510]. Structured distributing and collecting devices are the natural interest of information science. Unfortunately, of the 130 articles published about medicine in almost 36 years of JASIST, although 70 (54%) deal with information retrieval, communication and the work processes behind them, only 2 of these articles (1.5%) have focused on the medical record.

The body of existing information retrieval work most relevant to the medical record as a base for experiment is the work called “passage retrieval” defined as “the task of identifying and extracting fragments from large, or short but heterogeneous full text documents” (Melucci, 1998, p. 44).

This paper presents a document‐centered approach to the EHR as an information retrieval problem. It is clear that passage retrieval researchers working in the field of information science have seen similar values in document passages as have researchers in medical informatics. Without either literature acknowledging the other, workers in both camps have identified the same potential in document structure, labels, specificity and explicit hierarchies of knowledge for signaling relevance to the reader. The National Health Information Infrastructure Initiative (http://aspe.hhs.gov/sp/nhii/) identifies academics and researchers as natural stakeholders, like clinicians and caregivers, in enabling better healthcare through better information sharing (National Committee on Vital and Health Statistics, 2003). Information science has much to contribute to the health information technology arena and to electronic health records in particular: their development, their maintenance, and most importantly their improvement to serve the needs of diverse users.
On the integration schemes for Drucker–Prager's elastoplastic models based on exponential maps
Authors: Rezaiee‐Pajand M. , Nasirai Cyrus
Published: October 2007

Rate plasticity equations for the case of Drucker–Prager's model in small strain regime are considered. By defining an augmented stress vector, the formulations convert the original problem into a quasi‐linear differential equation system. Two new exponential mapping schemes for integrating model equations are proposed. In addition, two traditional schemes for solving the dynamical system in an explicit manner are discussed. The two semi‐implicit schemes developed pose higher accuracy and better convergency. Error contours are provided for all four methods to display the accuracy of each scheme. In order to compare the results, these contours for the classical one‐step backward Euler integration method are also displayed. Accuracy and efficiency along with the rate of convergency of the existing and the proposed methods are examined by numerical examples. Copyright © 2007 John Wiley & Sons, Ltd.
Computational fluid flow solution over endothelial cells inside the capillary vascular system
Authors: Arslan Nurullah , Erdogan Abdullah Said , Ashyralyev Allaberen
Published: November 2007

Computational blood flow analysis through glycocalyx located over the endothelial cells in human capillary vascular system is performed. Stable numerical schemes are developed for obtaining approximate solutions to the mixed problem to the partial differential equation with variable space operator to model the blood flow. Numerical techniques are developed by applying a procedure of the solution to the linear difference equation with matrix coefficients. The flow equations inside the core flow region and porous region are established. Discretization is done and the flow velocities in both regions are calculated. The effect of the flow over the glycocalyx is investigated. The wall shear stresses and the drag force over the glycocalyx are calculated. Copyright © 2007 John Wiley & Sons, Ltd.
Reactive compatibilization of nylon copolymer/EPDM blends: experimental aspects and their comparison with theory
Authors: Komalan Cibi , George K.E , Jacob Sinto , Thomas S.
Published: November 2007

In situ reactive compatibilization was first time applied to a low melting nylon (nylon 6 and 66 copolymer) and EPDM blend system. The effects of in situ compatibilization and concentration of compatibilizer on the morphology and mechanical properties of nylon/EPDM blends have been investigated. The influence of EPM‐g‐MA on the phase morphology was examined by the scanning electron microscopy (SEM) after preferential extraction of the minor phase. The SEM micrographs were quantitatively analyzed for domain size measurements. The compatibilizer concentrations used were 0, 1, 2.5, 5, and 10 wt%. The graft copolymer (nylon‐g‐EPM) formed at the interface showed relatively high emulsifying activity. A maximum phase size reduction was observed when 2.5 wt% of compatibilizer was added to the blend system. This was followed by a leveling‐off at higher loadings indicating interfacial saturation. The conformation of the compatibilizer at the interface was deduced based on the area occupied by the compatibilizer at the blend interface. The experimental compatibilization results were compared with theoretical predictions of Noolandi and Hong. It was concluded that the molecular state of compatibilizer at interface changes with concentration. The in situ compatibilized blends showed considerable improvement in mechanical properties. Measurement of tensile properties shows increased elongation as well as enhanced modulus and strength up on compatibilization. At higher concentrations of compatibilizer, a leveling‐off of the tensile properties was observed. A good correlation has been observed between the mechanical properties and morphological parameters. Copyright © 2007 John Wiley & Sons, Ltd.
In‐plane anisotropic permeability characterization of deformed woven fabrics by unidirectional injection. Part I: Experimental results
Authors: Demaría C. , Ruiz Edu , Trochu F.
Published: November 2007

Because of the increasing use of polymer composites in a wide variety of industrial applications, the manufacturing of complex composite parts has become an important research topic. When a part is manufactured by liquid composite molding (LCM), the reinforcement undergoes a certain amount of deformation after closure and sealing of the mold. In the case of bidirectional woven fabrics, this deformation may significantly affect the resin flow and mold filling because of changes in the values of permeability. Among other considerations that govern the accuracy of numerical simulations of mold filling, it is important to predict the changes of permeability as a function of the local shearing angle of the preform. The resin flow through a fibrous reinforcement is governed by Darcy's law, which states that the fluid flow rate is proportional to the pressure gradient. The shape of the flow front in a point‐wise injection through an anisotropic preform is an ellipse. Part I of this article describes a new methodology based on the ellipse equation to derive the in‐plane permeability tensor from unidirectional injection experiments in deformed woven fabrics. Part II presents a mathematical model that predicts the principal permeabilities and their orientation for sheared fabrics from the permeability characterization of unsheared fabrics. Unidirectional flow experiments were conducted for a nonstitched, balanced, woven fabric for different shearing angles and fiber volume fractions. This article presents experimental results for deformed and undeformed fabrics obtained by unidirectional flow measurements. A comparison of the proposed characterization methodology with radial flow experiments is also included. POLYM. COMPOS. 28:797–811, 2007. © 2007 Society of Plastics Engineers.
In‐plane anisotropic permeability characterization of deformed woven fabrics by unidirectional injection. Part II: Prediction model and numerical simulations
Authors: Demaría C. , Ruiz Edu , Trochu F.
Published: November 2007

The production of polymer composites by resin injection has strongly increased in the recent years for a wide variety of industrial applications. Manufacturing techniques are continuously optimized for higher and faster production cycles and high performance composites are needed to meet industrial requirements. Actually, the reduction of cost and cycle time is the main motivation for liquid composite molding (LCM) process simulation. In this context, the characterization of preform permeability is a key issue in numerical flow analysis. This investigation concerns the experimental study and development of a predictive model for deformed fabric permeability. Such deformations occur when a fabric is draped on a complex surface. A local shear appears. In Part I, an experimental procedure has been described to measure the permeability of deformed fabrics, and a new methodology presented to characterize the in‐plane permeability tensor. In order to implement experimental results in numerical simulation, a permeability model for deformed fabrics is required. Part II develops a predictive model of the principal permeabilities of deformed fabrics and of the orientation of the permeability tensor. Based on unsheared fabric measurements, the model takes into account the unit cell deformation during shear and the initial elliptic flow pattern orientation and anisotropy ratio of undeformed fabrics. Model predictions are corroborated with sheared fabric measurements. Finally, numerical simulations for an automotive body part are carried out to illustrate the effects of fabric shearing on the filling of the composite part. POLYM. COMPOS. 28:812–827, 2007. © 2007 Society of Plastics Engineers.
Viscoelastic response of nanocomposite poly(vinyl acetate)‐hydroxyapatite with varying particle shape—Dynamic strain softening and modulus recovery
Authors: Kalfus J. , Jancar J.
Published: November 2007

Dynamic‐strain softening known as the Payne effect was investigated in the case of poly(vinyl acetate)‐hydroxyapatite (PVAc‐HA) model nanocomposites in which the nanoparticles served as reversible physical cross‐links. HA nanofillers with different particle shape and with size ranging from 5 to 60 nm were used. Filler concentration in PVAc nanocomposites was limited to maximum of 5 vol%. Dynamic‐mechanical spectra were recorded as a function of structural variables, strain amplitude, and test temperature using the dynamic‐mechanical thermal spectroscopy (DMTS). Additionally, amplitude sweep tests were supplemented by the modulus recovery experiments to provide relaxation time data. Observed phenomena were interpreted using polymer physics approach. POLYM. COMPOS., 28:743–747, 2007. © 2007 Society of Plastics Engineers
Comparison of the curing kinetic behavior for two epoxy resin systems containing EPIKOTE 828–EPIKURE 3090 and DURATEK KLM 606A–DURATEK KLM 606B
Authors: Tüzün F. Nihal , Gürü Metin , Akyüz Yüksel
Published: November 2007

The aim of the study is to determine the optimum cure temperatures and kinetics for two different epoxy resin systems without using solvent. Two resin systems consist of EPIKOTE 828® epoxy resin–EPIKURE® 3090 polyamidoamine curing agent and DURATEK® KLM 606A epoxy resin–DURATEK® KLM 606B polyamide curing agent. The ratio of resin to curing agent was kept as 1:1 for both the systems. Curing temperatures of both the systems were determined and kinetic parameters were calculated with respect to the experimental results following nth‐order kinetics. Then, a series of isothermal temperatures was applied to the resin systems in order to assess the cure process in terms of conversion, time, and temperature by using differential scanning calorimeter (DSC). The test results of both systems show that the rate of degree of cure for EPIKOTE 828® epoxy resin–EPIKURE® 3090 polyamidoamine curing agent system is approximately 10 times higher than that of DURATEK® KLM 606A epoxy resin–DURATEK® KLM 606B polyamide curing agent system at 230°C. POLYM. COMPOS., 28:762–770, 2007. © 2007 Society of Plastics Engineers
Copolymerization of propylene with 1,3‐butadiene using isospecific zirconocene catalysts
Authors: Ishihara Takeshi , Ban Hoang The , Hagihara Hideaki , Shiono Takeshi
Published: October 2007

Poly(propylene‐ran‐1,3‐butadiene) was synthesized using isospecific zirconocene catalysts and converted to telechelic isotactic polypropylene by metathesis degradation with ethylene. The copolymers obtained with isospecific C2‐symmetric zirconocene catalysts activated with modified methylaluminoxane (MMAO) had 1,4‐inserted butadiene units (1,4‐BD) and 1,2‐inserted units (1,2‐BD) in the isotactic polypropylene chain. The selectivity of butadiene towards 1,4‐BD incorporation was high up to 95% using rac‐dimethylsilylbis(1‐indenyl)zirconium dichloride (Cat‐A)/MMAO. The molar ratio of propylene to butadiene in the feed regulated the number‐average molecular weight (Mn) and the butadiene contents of the polymer produced. Metathesis degradations of the copolymer with ethylene were conducted with a WCI6/SnMe4/propyl acetate catalyst system. The 1H NMR spectra before and after the degradation indicated that the polymers degraded by ethylene had vinyl groups at both chain ends in high selectivity. The analysis of the chain scission products clarified the chain end structures of the poly(propylene‐ran‐1,3‐butadiene). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5731–5740, 2007
Synthesis of core‐shell silver–polyaniline nanocomposites by gamma radiolysis method
Authors: Karim Mohammad Rezaul , Lim Kwon Taek , Lee Chul Jae , Bhuiyan Md Tauhidul Islam , Kim Hee Jin , Park Lee‐Soon , Lee Mu Sang
Published: October 2007

Core‐shell silver (Ag)–polyaniline (PAni) nanocomposites have been synthesized by the in‐situ gamma radiation‐induced chemical polymerization method. Aqueous solution of aniline, a free‐radical oxidant, and/or silver metal salt were irradiated by γ‐rays. Reduction of the silver salt in aqueous aniline leads to the formation of silver nanoparticles which in turn catalyze oxidation of aniline to polyaniline. The resultant Ag‐PAni nanocomposites were characterized by using different spectroscopy analyses like X‐ray photoelectron, UV–visible, and infrared spectroscopy. The optical absorption bands revealed that the bands at about 400 nm are due to the presence of nanosilver and the blue‐shifted peak at ∼ 555 nm is due to the presence of metallic silver within the PAni matrix. X‐ray diffraction pattern clearly indicates the broad amorphous polymer and the sharp metal peaks. Scanning electron microscopy and transmission electron microscopy of the nanocomposite showed a uniform size distribution with spherical and granular morphology. Thermogravimetric analysis revealed that the composites have a higher degradation temperature than polyaniline alone. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5741–5747, 2007
Synthesis and properties of polymethacrylate bearing cyclic carbonate through urethane linkage
Authors: Ochiai Bungo , Ootani Yuuko , Maruyama Tetsushi , Endo Takeshi
Published: October 2007

Polymethacrylates carrying cyclic carbonate through urethane linkage were prepared by radical (co)polymerizations of 2‐methacrylic acid 2‐(2‐oxo‐[1,3]dioxolan‐4‐ylmethoxycarbonylamino)ethyl ester (CUMA). Although brittleness of typical polymers bearing cyclic carbonate groups has been limited their practical applications, some copolymers from CUMA can be cast as films with good flexibility. The copolymers from CUMA and diethyleneglycol methyl ether methacrylate are miscible with lithium bis(trifluoromethanesulfone)imide. The coordination of the lithium cation to the carbonyl groups was confirmed by infrared spectrometry. © 2007 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 45: 5781–5789, 2007
Novel double hydrophilic block copolymers based on poly(p‐hydroxystyrene) derivatives and poly(ethylene oxide)
Authors: Mountrichas Grigoris , Pispas Stergios
Published: October 2007

The synthesis of three series of double hydrophilic block copolymers (DHBCs), consisting of poly(ethylene oxide) as the neutral water soluble block and a second polyelectrolyte block of variable chemistry, is described. The synthetic scheme involves the anionic polymerization of poly(p‐tert‐butoxystyrene‐b‐ethylene oxide) (PtBOS‐PEO) amphiphilic block copolymer precursors followed by the acidic hydrolysis of the hydrophobic poly(p‐tert‐butoxystyrene) (PtBOS) block to an annealed anionic polyelectrolyte poly(p‐hydroxystyrene) (PHOS) block. The PHOS block was subsequently transformed into a high charge density annealed cationic polyelectrolyte namely poly[3,5‐bis(dimethylaminomethylene) hydroxystyrene] (NPHOS), via aminomethylation. Finally, the NPHOS block was transformed into a quenched polyelectrolyte, namely quaternized poly[3,5‐bis(dimethylaminomethylene) hydroxystyrene] (QNPHOS) block by reaction with CH3I. The solution properties of the different series of the above block polyelectrolyte copolymers have been investigated using static, dynamic and electrophoretic light scattering, turbidimetry, and fluorescence spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5790–5799, 2007
Morphology of side chain liquid crystalline block copolymer thin films and effects of thermal annealing
Authors: Verploegen Eric , Boone Derrick , Hammond Paula T.
Published: October 2007

The self‐assembly behavior of siloxane based side chain liquid crystalline block copolymer thin films are investigated via grazing incidence small angle X‐ray scattering and atomic force microscopy. The as‐spun films displayed polystyrene cylinders perpendicular to the substrate and the cylinders reoriented parallel to the surface after thermal annealing. The morphology observed in the as‐spun films is resultant from the orientation of the smectic LC mesophase relative to the substrate. Annealing above both the polystyrene glass transition temperature and the smectic to isotropic transition temperature eliminates the influence of the LC phase, leading to a reorientation of the morphology that minimizes the interfacial energy of the system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3263–3266, 2007
Electrical Discharges in Mixtures of Light and Heavy Water
Authors: Mededovic Selma , Finney Wright C. , Locke Bruce R.
Published: October 2007

Pulsed electrical discharges in pure solutions and mixtures of light and heavy water are examined. The concentration of H2O2 formed by electrical discharge in 100% H2O was found to be 1.4 times smaller than that of D2O2 produced by electrical discharge in 100% D2O. This difference in peroxide formation was due to the high reactivity of OH radicals with other species in the plasma channel, thereby reducing OH recombination to form H2O2, while the lower reactivity of OD radicals with other species allowed more OD recombination reactions to form D2O2. A new method based on Raman spectroscopy was also developed to quantify H2O2, D2O2, and HDO2 in mixtures containing all three species.

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Molecular modeling of the second extracellular loop of G‐protein coupled receptors and its implication on structure‐based virtual screening
Authors: de Graaf Chris , Foata Nicolas , Engkvist Ola , Rognan Didier
Published: October 2007

The current study describes the validation of high‐throughput modeling procedures for the construction of the second extracellular loop (ecl2) of all nonolfactory human G Protein‐coupled receptors. Our modeling flowchart is based on the alignment of essential residues determining the particular ecl2 fold observed in the bovine rhodopsin (bRho) crystal structure. For a set of GPCR targets, the dopamine D2 receptor (DRD2), adenosine A3 receptor (AA3R), and the thromboxane A2 receptor (TA2R), the implications of including ecl2 atomic coordinates is evaluated in terms of structure‐based virtual screening accuracy: the suitability of the 3D models to distinguish between known antagonists and randomly chosen decoys using automated docking approaches. The virtual screening results of different models describing increasingly exhaustive receptor representations (seven helices only, seven helices and ecl2 loop, full model) have been compared. Explicit modeling of the ecl2 loop was found to be important in only one of three test cases whereas a loopless model was shown to be accurate enough in the two other receptors. An exhaustive comparison of ecl2 loops of 365 receptors to that of bRho suggests that explicit ecl2 loop modeling should be reserved to receptors where loop building can be guided by experimental restraints. Proteins 2008; 71:599–620. © 2007 Wiley‐Liss, Inc.
Cluster conservation as a novel tool for studying protein–protein interactions evolution
Authors: Rahat Ofer , Yitzhaky Assif , Schreiber Gideon
Published: October 2007

Protein–protein interactions networks has come to be a buzzword associated with nets containing edges that represent a pair of interacting proteins (e.g. hormone‐receptor, enzyme‐inhibitor, antigen‐antibody, and a subset of multichain biological machines). Yet, each such interaction composes its own unique network, in which vertices represent amino acid residues, and edges represent atomic contacts. Recent studies have shown that analyses of the data encapsulated in these detailed networks may impact predictions of structure–function correlation. Here, we study homologous families of protein–protein interfaces, which share the same fold but vary in sequence. In this context, we address what properties of the network are shared among relatives with different sequences (and hence different atomic interactions) and which are not. Herein, we develop the general mathematical framework needed to compare the modularity of homologous networks. We then apply this analysis to the structural data of a few interface families, including hemoglobin α–β, growth hormone‐receptor, and Serine protease‐inhibitor. Our results suggest that interface modularity is an evolutionarily conserved property. Hence, protein–protein interfaces can be clustered down to a few modules, with the boundaries being evolutionarily conserved along homologous complexes. This suggests that protein engineering of protein–protein binding sites may be simplified by varying each module, but retaining the overall modularity of the interface. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Component D of chicken hemoglobin and the hemoglobin of the embryonic Tammar wallaby (Macropus eugenii) self‐associate upon deoxygenation: Effect on oxygen binding
Authors: Rana Mitra S. , Knapp James E. , Holland Robert A. B. , Riggs Austen F.
Published: October 2007

Extensive measurements of oxygen binding by some vertebrate hemoglobins (Hbs) have suggested an unusually high degree of cooperativity with reported Hill coefficients, nH, greater than 4.0. We have reexamined this possibility of “super‐cooperativity” with chicken Hb components A (αA2β2) and D (αD2β2). Prior studies have shown that component D but not A self‐associates to dimers of tetramers upon deoxygenation. This self‐association is reflected in the oxygen equilibrium of Hb D which shows a maximal nH, greater than 4.0 at ∼4 mM heme concentration. In contrast, component A has maximal nH value below 3. The value of the maximal nH for Hb D increases linearly with the fraction of octamer present in the deoxy Hb. We anticipate that deoxygenation‐dependent self‐association will be shown to be a general property of Hb D from birds and reptiles. Neither oxygen equilibria nor sedimentation measurements show any evidence that components A and D interact to form a complex when deoxygenated. We have also reexamined the oxygen equilibria of Hbs of an embryonic marsupial, the wallaby. The equilibria in red cells have been reported to have Hill coefficients as high as 5–6. Although our oxygen equilibrium measurements of solutions of unfractionated wallaby Hb at a concentration of ∼1 mM show no nH values greater than ∼3.0, sedimentation velocity measurements provide clear evidence for deoxygenation‐dependent self‐association. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Susceptibility to thiamethoxam of Musca domestica from Danish livestock farms
Authors: Kristensen Michael , Jespersen Jørgen B
Published: October 2007

BACKGROUND: Neonicotinoid baits are currently replacing anticholinesterase baits for control of adult houseflies (Musca domestica L.). Introduction of new insecticides includes evaluation of their cross‐resistance potential, which was assessed for thiamethoxam in field populations from Denmark.

RESULTS: In feeding bioassay with a susceptible strain, thiamethoxam LC50 at 72 h was 1.7 µg thiamethoxam g−1 sugar, making it 19‐fold, 11‐fold and threefold more toxic to houseflies than azamethiphos, methomyl and spinosad respectively. The field populations were 6–76‐fold resistant to thiamethoxam. There was no correlation between the toxicities of thiamethoxam and spinosad, dimethoate, methomyl, bioresmethrin or azamethiphos. The toxicity in feeding bioassay at 72 h of imidacloprid in a susceptible strain was 32 µg imidacloprid g−1 sugar at LC50, making it 19‐fold less toxic to houseflies than thiamethoxam. There was a strong significant correlation between the toxicities of thiamethoxam and imidacloprid in field populations.

CONCLUSION: Neonicotinoid‐resistant houseflies were present at a detectable and noticeable level before thiamethoxam and imidacloprid were introduced for housefly control in Denmark. The toxicity of thiamethoxam is explained by other parameters than the toxicities of spinosad, dimethoate, methomyl, bioresmethrin or azamethiphos. The cross‐resistance between thiamethoxam and imidacloprid indicates a coincidence of mechanism of the toxicity and resistance in the field populations. Copyright © 2007 Society of Chemical Industry
Involvement of excited triplet state in the photodissociation of cyclobutane
Authors: Lei Yibo , Suo Bingbing , Li Anyang , Dou Yusheng , Wang Yubin , Wen Zhenyi
Published: October 2007

The potential energy curves (PECs) of the ground state and the low‐lying excited states for the photodissociation of cyclobutane have been calculated at the multi‐reference configuration interaction with singlet and doublet excitation (MRCISD) and the multi‐reference second order perturbation theory (MRPT2). Firstly, the PECs are constructed following a reaction path determined by semiclassical dynamics simulation, which suggests that the lowest triplet state of tetramethylene is involved in the photodissociation of cyclobutane. Then, the adiabatic PECs are calculated for the breaking processes of C1C3 and C2C4 bond respectively. The singlet‐triplet PECs' intersections have been found in the two breaking CC bond processes. During the breaking process of the second C2C4 bond, a local minimum has been found on the PEC of the lowest triplet state, which gives us some insight to reinterpret the experimental observed diradical intermediate as being trapped in its triplet state. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
How the System Dynamics Society came to be: a collective memoir
Authors: Andersen David , Morecroft John , Spencer Roberta , Forrester Jay , Karsky Michel , Paulré Bernard , Pugh Jack , Radzicki Michael , Randers Jørgen , Richardson George , Saeed Khalid , Wolstenholme Eric
Published: October 2007

In this paper several of the early workers in the field of system dynamics tell some of the history of the Society itself. Several slightly different versions of this story have been told over the past several years and we thought it would be interesting to involve a broader group in this kind of modified oral history project. The paper is based on a series of separate written recollections that have been posted in full on the web at http://www.systemdynamics.org/history/oral_history.htm. Copyright © 2007 John Wiley & Sons, Ltd.
The power of the bond between cause and effect: Jay Wright Forrester and the field of system dynamics
Authors: Lane David C.
Published: October 2007

This article presents a treatment of Jay Wright Forrester's life and achievements. The concentration is on the intellectual provenance, emergence and growth of system dynamics. Copyright © 2007 John Wiley & Sons, Ltd.
A brief and incomplete history of operational gaming in system dynamics
Authors: Meadows Dennis
Published: October 2007

I provide a personal reflection on the history of interactive gaming and “management flight simulators” in system dynamics, offering practical advice on the attributes of effective games and gaming. Copyright © 2007 John Wiley & Sons, Ltd.
Application of system dynamics to corporate strategy: an evolution of issues and frameworks
Authors: Weil Henry Birdseye
Published: October 2007

I discuss five projects that became important building blocks in the application of system dynamics to corporate strategy. The first captures the tension among conflicting performance objectives and their impact on company performance. The second represents an R&D organization as it responds to changing pressures and direction from management. The third explains the progressive “commoditization” of products and services. The fourth examines the dynamics of innovative industries. The final model focuses on the market impacts of social factors, e.g., trust, fashion, bandwagon effects and network effects. The progression began with classical industrial dynamics models focused on orders, production, and shipments. Each milestone marks greater behavioral richness and complexity. What do we know now that we did not know when the field was founded fifty years ago? The most important lessons concern the critical roles of organizational, social, and psychological factors in important business decisions, competition and the evolution of markets. Copyright © 2007 John Wiley & Sons, Ltd.
Nonlinear dynamic phenomena in the beer model
Authors: Mosekilde Erik , Laugesen Jakob L.
Published: October 2007

The production–distribution system or “beer game” is one of the most well‐known system dynamics models. Notorious for the complex dynamics it produces, the beer game has been used for nearly five decades to illustrate how structure generates behavior and to explore human decision making. Here we present a formal bifurcation analysis to analyse the complex dynamics produced by the model. Consistent with the rules of the game, the model constitutes a piecewise‐linear map with nonlinearities arising from non‐negativity constraints. The bifurcations that occur in piecewise‐linear systems are distinctly different from those observed in smooth systems. We show how the model displays abrupt Hopf and period‐doubling bifurcations, truncated bifurcation cascades, and various border‐collision bifurcations. The latter allow direct transitions from periodic to chaotic dynamics. Bifurcation phenomena in models that use piecewise‐linear functions to represent nonlinearities are likely to show similar qualitative differences from the bifurcations known from smooth systems. Copyright © 2007 John Wiley & Sons, Ltd.
Chronic illness in a complex health economy: the perils and promises of downstream and upstream reforms
Authors: Homer Jack , Hirsch Gary , Milstein Bobby
Published: October 2007

Chronic illness is the largest cause of death and source of health care costs in developed countries and a growing problem in developing countries. Here we build on past work in system dynamics and present a generic model of chronic illness, its treatment and prevention, applied to the U.S. population. The model explains the rising prevalence of illness and responses to it, including the treatment of complications and management activities designed to reduce complications. We show how progress in treatment and disease management has slowed since 1980 in the U.S., largely due to competition between health care payers and providers, resulting in price inflation and an unstable climate for health care investments. We demonstrate the impact of moving “upstream” by managing known risk factors to prevent illness onset, and moving even further upstream by addressing behaviors and living conditions linked to the initial development of these risk factors. Copyright © 2007 John Wiley & Sons, Ltd.
Exploring the next great frontier: system dynamics at fifty
Authors: Sterman John D.
Published: October 2007

This note introduces the special issue of the System Dynamics Review celebrating the 50th anniversary of the founding of the field. Copyright © 2007 John Wiley & Sons, Ltd.
System dynamics—a personal view of the first fifty years
Authors: Forrester Jay W.
Published: October 2007

I present a personal recollection of the history of system dynamics and observations about its present state. The article treats the history in two parts: first, my personal background and how all the threads came together to initiate the field of system dynamics; and second, the historical development of the cornerstone projects that shaped the field. These early works include industrial dynamics, urban dynamics, world dynamics, and the national economic model. The paper continues with an assessment of the present condition of the field. A companion paper (System Dynamics—The Next Fifty Years, also in this issue of System Dynamics Review), highlights challenges for the future. Copyright © 2007 Jay W. Forrester.
A meta‐analysis of national research: Effects of teaching strategies on student achievement in science in the United States
Authors: Schroeder Carolyn M. , Scott Timothy P. , Tolson Homer , Huang Tse‐Yang , Lee Yi‐Hsuan
Published: October 2007

This project consisted of a meta‐analysis of U.S. research published from 1980 to 2004 on the effect of specific science teaching strategies on student achievement. The six phases of the project included study acquisition, study coding, determination of intercoder objectivity, establishing criteria for inclusion of studies, computation of effect sizes for statistical analysis, and conducting the analyses. Studies were required to have been carried out in the United States, been experimental or quasi‐experimental, and must have included effect size or the statistics necessary to calculate effect size. Sixty‐one studies met the criteria for inclusion in the meta‐analysis. The following eight categories of teaching strategies were revealed during analysis of the studies (effect sizes in parentheses): Questioning Strategies (0.74); Manipulation Strategies (0.57); Enhanced Material Strategies (0.29); Assessment Strategies (0.51); Inquiry Strategies (0.65); Enhanced Context Strategies (1.48); Instructional Technology (IT) Strategies (0.48); and Collaborative Learning Strategies (0.95). All these effect sizes were judged to be significant. Regression analysis revealed that internal validity was influenced by Publication Type, Type of Study, and Test Type. External validity was not influenced by Publication Year, Grade Level, Test Content, or Treatment Categories. The major implication of this research is that we have generated empirical evidence supporting the effectiveness of alternative teaching strategies in science. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 1436–1460, 2007
Exploring the factors related to acceptance of evolutionary theory among Turkish preservice biology teachers: Toward a more informative conceptual ecology for biological evolution
Authors: Deniz Hasan , Donnelly Lisa A. , Yilmaz Irfan
Published: November 2007

In this study, using multiple regression analysis, we aimed to explore the factors related to acceptance of evolutionary theory among preservice Turkish biology teachers using conceptual ecology for biological evolution as a theoretical lens. We aimed to determine the extent to which we can account for the variance in acceptance of evolutionary theory by using understanding of evolutionary theory, epistemological beliefs, thinking dispositions, and parents' educational level as independent variables. Preservice biology teachers' thinking dispositions, their understanding of evolutionary theory, and their parents' educational level are positively correlated with acceptance of evolutionary theory. We did not find any significant positive correlation between epistemological beliefs and acceptance of evolution because of low reliability coefficients of subscales of the epistemological beliefs instrument. Together they explained 10.5% of the variance. These results suggest that studying the relationship between acceptance of evolutionary theory and other related factors in a multivariate context is more informative than examining the relationship between acceptance of evolutionary theory and other factors in isolation. Our findings indicate that studying a controversial issue such as acceptance of evolutionary theory in a multivariate fashion, using conceptual ecology as a theoretical lens to interpret the findings, is informative. Our results suggest the inclusion of thinking dispositions in conceptual ecology for biological evolution. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 45: 420–443, 2008
Reproductive and thyroid hormone profiles in captive Western fence lizards (Sceloporus occidentalis) after a period of brumation
Authors: Brasfield Sandra M. , Talent Larry G. , Janz David M.
Published: November 2007

Seasonal fluctuation in serum concentrations of sex steroid (testosterone [T] and 17β‐estradiol [E2]) and thyroid (triiodothyronine [T3] and thyroxine [T4]) hormones was determined in captive Western fence lizards (Sceloporus occidentalis). Samples were collected from male and female breeding pairs weekly for a 4‐month period after their emergence from artificial brumation. Circulating levels of E2 corresponded with the expected vitellogenic and ovulatory cycles in females, and surprisingly, E2 in males followed a similar pattern, indicating a possible role in breeding behavior. Serum T was elevated in male lizards for the first 6 weeks after emergence from brumation, possibly related to an increase in the onset of active spermatogenesis. Thyroid hormones showed little cyclical activity throughout the breeding period, with the exception of small increases of T3 at weeks 8 and 16, possibly implying an active role of this hormone with ovulation in females. Overall, these baseline hormone data are not only useful in developing this animal as a laboratory reptile model for assessment of endocrine‐mediated toxicity, but also of value for understanding herpetological endocrinology and for application in the conservation of threatened species. Zoo Biol 27:36–48, 2008. © 2007 Wiley‐Liss, Inc.
Antioxidant Activity of Raisin Extracts in Bulk Oil, Oil in Water Emulsion, and Sunflower Butter Model Systems
Authors: Zhao Bin , Hall Clifford A.
Published: October 2007

The antioxidant activities of the raisin extract (RE) in stripped corn oil, stripped corn oil emulsions, and sunflower butter stored at 60 °C for up to 15 days was evaluated. Peroxide values and hexanal content were measured on a half day, 2 or 3 day basis for the emulsion, sunflower butter, and bulk oil, respectively. The RE had the best antioxidant activity in the bulk oil system. Statistical contrasts indicated the oxidation of bulk corn oil treated with RE was significantly (p < 0.001 and p = 0.044) lower than bulk oil and bulk oil treated with tertiary‐butylhydroquinone (TBHQ), respectively. No differences (p = 0.15) in hexanal concentrations were observed in stored bulk oils treated with RE and TBHQ. However, both these materials inhibited hexanal formation better (p < 0.001) when compared to the control corn oil. In contrast, 200 μg/g TBHQ had better (p = 0.0004) antioxidant activity than 3,000 μg/g RE in the oil in water(o/w) emulsion. No significant differences (p = 0.1637) in hexanal formation were observed in the emulsions treated with RE and TBHQ. However, the data indicated that the RE treated emulsion did undergo more secondary oxidation than the emulsion treated with TBHQ beyond 110 h. The 3,000 μg/g RE had antioxidant activity in sunflower butter, but was less effective than the 200 μg/g TBHQ and a lower RE concentration (200 μg/g). The observations supported the hypothesis that RE has antioxidant activity in the multiple model systems.
Differential effect of sanguinarine, chelerythrine and chelidonine on DNA damage and cell viability in primary mouse spleen cells and mouse leukemic cells
Authors: Kaminskyy Vitaliy , Lin Kah‐Wai , Filyak Yevhen , Stoika Rostyslav
Published: October 2007

Sanguinarine, chelerythrine and chelidonine are isoquinoline alkaloids derived from the greater celandine. They possess a broad spectrum of pharmacological activities. It has been shown that their anti‐tumor activity is mediated via different mechanisms, which can be promising targets for anti‐cancer therapy. We focused our study on the differential effects of these alkaloids upon cell viability, DNA damage effect and nucleus integrity in mouse primary spleen cells and mouse lymphocytic leukemic cells, L1210. Sanguinarine and chelerythrine produce a dose‐dependent increase in DNA damage and cytotoxicity in both primary mouse spleen cells and L1210 cells. Chelidonine did not show a significant cytotoxicity or damage DNA in both cell types, but completely arrested growth of L1210 cells. Examination of nuclear morphology revealed more cells with apoptotic features upon treatment with chelerythrine and sanguinarine, but not chelidonine. In contrast to primary mouse spleen cells, L1210 cells showed slightly higher sensitivity to sanguinarine and chelerythrine treatment. This suggests that cytotoxic and DNA damaging effects of chelerythrine and sanguinarine are more selective against mouse leukemic cells and primary mouse spleen cells, whereas chelidonine blocks proliferation of L1210 cells. The action of chelidonine on normal and tumor cells requires further investigation.
A novel family of single VWC‐domain proteins in invertebrates
Authors: Sheldon T.J. , Miguel-Aliaga I. , Gould A.P. , Taylor W.R. , Conklin D.
Published: October 2007

Using a combination of sequence analysis tools, a novel family of 13 short Drosophila melanogaster proteins with similarity to a single von Willebrand factor C‐domain (SVC proteins) has been identified. SVCs are predicted to be secreted and a structural model for the family is proposed, using a known von Willebrand factor C‐domain (VWC) structure as template. All SVCs possess eight cysteines, consistent with the loss of one bonded pair from the 10‐cysteine canonical pattern of most VWC domains. Unlike most Drosophila genes, many SVCs are not expressed during development, and misexpression has no apparent effect on development or viability. SVCs appear to be restricted to arthropods. A role for SVCs in response to environmental challenges is proposed.
Role of AF6 protein in cell‐to‐cell spread of Herpes simplex virus 1
Authors: Keyser Johanna , Lorger Mihaela , Pavlovic Jovan , Radziwill Gerald , Moelling Karin
Published: October 2007

AF6 and its rat homologue afadin are multidomain proteins localized at cell junctions and involved in intercellular adhesion. AF6 interacts via its PDZ domain with nectin‐1 at epithelial adherens junctions. Nectin‐1 serves as a mediator of cell‐to‐cell spread for Herpes simplex virus 1 (HSV‐1). We analyzed the role of AF6 protein in the viral spread and nectin‐1 clustering at cell–cell contacts by knockdown of AF6 in epithelial cells. AF6 knockdown reduced efficiency of HSV‐1 spreading, however, the clustering of nectin‐1 at cell–cell contacts was not affected. Thus, AF6 protein is important for spreading of HSV‐1 in epithelial cells, independently of nectin clustering, possibly by stabilization of the E‐cadherin‐dependent cell adhesion.
CSF‐1 and TPA stimulate independent pathways leading to lysosomal degradation or regulated intramembrane proteolysis of the CSF‐1 receptor
Authors: Glenn Gary , van der Geer Peter
Published: October 2007

The CSF‐1 receptor is a protein‐tyrosine kinase that has been shown to undergo regulated intramembrane proteolysis, or RIPping. Here, we have compared receptor downregulation and RIPping in response to CSF‐1 and TPA. Our studies show that CSF‐1 is a relatively poor inducer of RIPping and that CSF‐1‐induced receptor downregulation is largely independent of RIPping. TPA is a strong inducer of RIPping and TPA‐induced receptor downregulation is mediated by RIPping. We further found that RIPping is dependent on TACE or a TACE‐like protease, that CSF‐1 and TPA use independent pathways to initiate RIPping, and that the intracellular domain is targeted for degradation through ubiquitination.