bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic and thermodynamic considerations in the synthesis of a new three‐arm poly(ε‐caprolactone)
Authors: Balakrishnan Sunder , Krishnan Mohan , Dubois Philippe , Narayan Ramani
Published: August 2004

A new high‐molecular‐weight three‐arm poly(ε‐caprolactone) (PCL) polymer was synthesized in bulk (in the absence of any solvent) by using aluminum tri‐sec butoxide as a tri‐functional initiator. The ring‐opening polymerization of ε‐caprolactone occurs via a coordination‐insertion mechanism that links three growing polyester chains to the Al central atom via metal alkoxide bonds. The global kinetics of the bulk polymerization was determined, and a kinetic model based on monomer‐polymer equilibrium was developed to predict the fractional extent of monomer conversion. Monomer conversions in excess of 95% to form high‐molecular‐weight PCL were achieved. Polym. Eng. Sci. 44:1491–1497, 2004. © 2004 Society of Plastics Engineers.
The effect of surface energy of boron nitride on polymer processability
Authors: Rathod Nimish , Hatzikiriakos Savvas G.
Published: August 2004

Flow instabilities manifest themselves as distortions on the extrudate surface (melt fracture). They are usually observed at high production rates in many polymer processing operations. Certain fluoropolymers/fluoroelastomers have long been used as processing aids for surface melt fracture elimination. Recent developments have shown that a small amount of boron nitride (BN) powder may successfully eliminate surface melt fracture and also delay the onset of gross melt fracture to higher rates. It has also been reported that a combination of BN and fluoropolymer/fluoroelastomer enhances the effectiveness of the polymer processing even further. The main objective of the present work was to measure the surface properties of a number BN powders, mainly surface energy, in order to gain a better understanding of its performance as a processing aid. Based on this study, it can be concluded that surface energy plays an important role in deciding the possible interactions between the processing aid, polymer melt and the extruding surface. It is observed that the lubricious nature of BN along with an optimum balance of its polar (non‐dispersive) and non‐polar (dispersive) components of surface energy renders BN a successful processing aid in eliminating both sharkskin and gross melt fracture phenomena. Polym. Eng. Sci. 44:1543–1550, 2004. © 2004 Society of Plastics Engineers.
Relationship between cell morphology and impact strength of microcellular foamed high‐density polyethylene/polypropylene blends
Authors: Rachtanapun Pornchai , Selke Susan E. M. , Matuana Laurent M.
Published: August 2004

Polymer blends, such as those resulting from recycling postconsumer plastics, often have poor mechanical properties. Microcellular foams have been shown to have the potential to improve properties, and permit higher‐value uses of mixed polymer streams. In this study, the effects of microcellular batch processing conditions (foaming time and temperature) and HDPE/PP blend compositions on the cell morphology (the average cell size and cell‐population density) and impact strength were studied. Optical microscopy was used to investigate the miscibility and crystalline morphology of the HDPE/PP blends. Pure HDPE and PP did not foam well at any processing conditions. Blending facilitated the formation of microcellular structures in polyolefins because of the poorly bonded interfaces of immiscible HDPE/PP blends, which favored cell nucleation. The experimental results indicated that well‐developed microcellular structures are produced in HDPE/PP blends at ratios of 50:50 and 30:70. The cell morphology had a strong relationship with the impact strength of foamed samples. Improvement in impact strength was associated with well‐developed microcellular morphology. Polym. Eng. Sci. 44:1551–1560, 2004. © 2004 Society of Plastics Engineers.
Deformation and morphology development of poly(ethylene terephthalate)/polyethylene and polycarbonate/polyethylene blends with high interfacial contact during elongation
Authors: Li Zhong‐Ming , Fu Xiao‐Rong , Yang Shuying , Yang Ming‐Bo , Yang Wei , Huang Rui
Published: August 2004

Immiscible blends of poly(ethylene terephthalate) (PET)/polyethylene (PE) and polycarbonate (PC)/PE were examined to study the influence of the high interfacial contact (pseudo‐adhesion) on the mechanical properties and the morphology developed during elongation. The high interfacial contact resulted from the contraction difference of the two polymers during cooling from the processing temperature to room temperature. As a result of the pseudo‐adhesion, the tensile strength and modulus of the PET/PE and PC/PE blends increased steadily with the increase of PET and PC concentration. In PC/PE blends, numerous PC microfibers were formed in‐situ, while in PET/PE blends, slippage took place between the PET particles and the matrix. Moreover, the macroscopic morphology development of both blends upon elongation was quite different. For PET/PE blend, necking was initiated at one point close to the non‐gate end of the specimen, and then propagated uniformly from this point. For the PC/PE blend, necking‐initating sites and propagation were irregular, and consequently the whole tested zone was deformed. The recoil of partially elongated specimens indicated that the recoverability of the PC/PE blend is higher than that of the PET/PE blend. Polym. Eng. Sci. 44:1561–1570, 2004. © 2004 Society of Plastics Engineers.
Capacitive transducer for in‐mold monitoring of injection molding
Authors: Chen Xi , Chen Guohua , Gao Furong
Published: August 2004

A capacitive transducer is developed for online monitoring of the in‐mold material status for injection molding, particularly for measurements of melt‐front position and flow‐rate. This paper will show, in addition to fulfilling its design purposes, that such a sensor can also be effectively used for the detection of the start and end of mold filling, the time of gate freezing, and over‐packing. Polym. Eng. Sci. 44:1571–1578, 2004. © 2004 Society of Plastics Engineers.
Recycled poly(ethylene terephthalate) chain extension by a reactive extrusion process
Authors: Awaja Firas , Daver Fugen , Kosior Edward
Published: August 2004

A commercial‐scale reactive extrusion processing system for recycled poly(ethylene terephthalate) (PET) flakes with an added chain extender, pyromellitic dianhydride (PMDA), was investigated. The PMDA concentration was varied with the intention of reaching a higher recycled PET intrinsic viscosity ([η]). The effect of changing the extruder residence time on the system's stability and the recycled PET [η] was also investigated. Reactive extruded PET with a PMDA concentration up to 0.3 wt% was found to have a higher [η] and lower carboxyl content than recycled PET processed in a normal extrusion system. A shift in [η] of about 0.18 dl/g was obtained with a 0.3 wt% PMDA concentration. A PMDA concentration above 0.3 wt% produced chemical, thermal and hydrodynamic instability in the system, causing crosslinking reactions and gel formation. The reactive extrusion system was stable at low residence time (45 s) and moderate (0.15 wt%) PMDA concentration; however, using 0.2 wt% PMDA produced higher reactive extruded recycled PET [η] with lower carboxyl content than other PMDA concentration levels examined. Residence times higher than 45 s produced higher reactive extruded recycled PET [η]. Reactive extruded recycled PET was also tested for mechanical properties. Polym. Eng. Sci. 44:1579–1587, 2004. © 2004 Society of Plastics Engineers.
Biodegradable polymers with variable architectures via ring‐expansion polymerization
Authors: Kricheldorf Hans R.
Published: August 2004

Kinetically controlled ring‐expansion polymerizations (REPs) are defined syntheses generating cyclic oligomers and polymers without linear intermediates and without equilibration reactions. This review reports syntheses of cyclic metal alkoxides and their use as initiators for REPs of lactones, cyclic diesters, and cyclocarbonates. In addition to homopolyesters, telechelic oligoesters or polyesters, random copolyesters, and A–B–A triblock copolymers can be prepared by these REPs. The in situ combination of REPs with condensation (mostly acylation) reactions allows a broad variation of end groups. The in situ combination of REPs with polycondensation enables various chain‐extension reactions, including the syntheses of multiblock copolymers. With spirocyclic initiators, four‐armed stars with functional end groups may be prepared. The in situ combination of REPs with condensation reactions of trifunctional or multifunctional reagents makes a broad variety of networks accessible. The average segment lengths may be controlled via the monomer/initiator ratios of the REP. All materials produced via the aforementioned REP processes are biodegradable and nontoxic, and this allows for biomedical and pharmaceutical applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4723–4742, 2004
Charge transfer interactions in polyesters with a donor‐(σ‐bridge)‐acceptor moiety in the repeating unit
Authors: Oosterbaan Wibren D. , Kaats‐Richters Veronica E. M. , Jenneskens Leonardus W. , Van Walree Cornelis A.
Published: August 2004

Two high molecular weight linear polyesters were investigated to gain insight in how the photophysics of electron donor‐(σ‐spacer)‐electron acceptor (DσA) compounds are affected by incorporation into a polymer. They were prepared by condensation of either adipoyl or sebacoyl chloride with a diol that was functionalized with an N,N‐dialkylaniline donor, a cyclohexyl type σ‐spacer, and a 1,1‐dicyanovinyl acceptor. The solubility, which is very low, and the thermal properties of the polyesters are dictated by physical crosslinking as a consequence of interchain donor‐acceptor interactions. Charge transfer (CT) absorption and emission are observed, which involve CT between DσA moieties of different chains rather than CT processes within a single DσA unit. As a result, the photophysics of the DσA units in the polyesters differs strongly from that of similar DσA compounds in solution. Upon swelling the polymers with THF, the CT fluorescence disappears partly. Analogous polymers containing only an N,N‐dialkylaniline donor display dual fluorescence; one band reflects local emission, while the other is attributed to excimer emission. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4775–4784, 2004
Poly[2,7‐(9,9‐dihexylfluorene)‐alt‐pyridine] with donor‐acceptor architectures: A new series of blue‐light‐emitting alternating copolymers
Authors: Liu Shou‐Ping , Chan Hardy S. O. , Ng Siu‐Choon
Published: August 2004

A novel series of well‐defined alternating poly[2,7‐(9,9‐dihexylfluorenyl)‐alt‐pyridinyl] (PDHFP) with donor‐acceptor repeat units were synthesized using palladium (0)‐catalyzed Suzuki cross‐coupling reactions in good to high yields. In this series of alternating polymers, 2, 7‐(9,9‐dihexylfluorenyl) was used as the light emitting unit, and the electron deficient pyridinyl unit was employed to provide improved electron transportation. These polymers were characterized by 1H‐NMR and 13C‐NMR, gel permeation chromatography (GPC), thermal analyses, and UV‐vis and fluorescence spectroscopy. The glass transition temperature of copolymers in nitrogen ranged from 110 to 148 °C, and the copolymers showed high thermal stabilities with high decomposition temperatures in the range of 350 to 390 °C in air. The difference in linkage position of pyridinyl unit in the polymer backbone has significant effects on the electronic and optical properties of polymers in solution and in film phases. Meta‐linkage (3,5‐ and 2,6‐linkage) of pyridinyl units in the polymer backbone is more favorable to polymer for pure blue emission and prevention of aggregation of polymer chain than para‐linkage (2,5‐linkage) of the pyridinyl units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4792–4801, 2004
Conformational changes and phase transformation mechanisms in PVDF solution‐cast films
Authors: Salimi A. , Yousefi A. A.
Published: August 2004

The supramolecular crystal structure in poly(vinylidene fluoride) (PVDF) solution‐cast films is studied through changing crystallization conditions in two solvents of different structures and polarities. The crystalline‐state chain conformations of isothermally solution‐crystallized PVDF in N, N‐dimethylacetamide (DMAc), and cyclohexanone are studied through the specific FTIR absorption bands of α, β, and γ phase crystals. There are no changes in the FTIR spectra of cyclohexanone solution‐crystallized films in the temperature range of 50–120 °C. In the case of DMAc solution‐crystallized films, low temperature crystallization mainly results in formation of trans states (β and γ phases), whereas at higher temperatures gauche states become more populated (α phase). This is due to the variations in solvent polarity and ability to induce a specific conformation in PVDF chains, through the changes in chain coil dimensions. This indicates that in spite of cyclohexanone solutions, the intermolecular interactions between PVDF and DMAc are temperature‐sensitive and more important in stabilizing conformations of PVDF in crystalline phase than temperature dependence of PVDF chain end‐to‐end distance . The high‐resolution 19F NMR spectroscopy also showed little displacement in PVDF characteristic chemical shifts probably due to changes in PVDF chain conformation resulting from temperature variations. Upon uniaxial stretching of the prepared films under certain conditions, contribution of trans state becomes more prominent, especially for the originally higher α phase‐containing films. Due to formation of some kink bands during film stretching and phase transformation, α phase absorption bands are still present in infrared spectra. Besides, uniaxial stretching greatly enhances piezoelectric properties of the films, maybe due to formation of oriented β phase crystals, which are of more uniform distribution of dipole moments. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3487–3495, 2004
Control of self‐organized low‐dimensional morphology in poly(styrene‐b‐4vinylpyridine)/polystyrene blend thin films
Authors: Zhao Junchai , Jiang Shichun , Ji Xiangling , An Lijia , Jiang Bingzheng
Published: August 2004

The surface morphologies of poly(styrene‐b‐4vinylpyridine) (PS‐b‐P4VP) diblock copolymer and homopolystyrene (hPS) binary blend thin films were investigated by atomic force microscopy as a function of total volume fraction of PS (ϕPS) in the mixture. It was found that when hPS was added into symmetric PS‐b‐P4VP diblock copolymers, the surface morphology of this diblock copolymer was changed to a certain degree. With ϕPS increasing at first, hPS was solubilized into the corresponding domains of block copolymer and formed cylinders. Moreover, the more solubilized the hPS, the more cylinders exist. However, when the limit was reached, excessive hPS tended to separate from the domains independently instead of solubilizing into the corresponding domains any longer, that is, a macrophase separation occurred. A model describing transitions of these morphologies with an increase in ϕPS is proposed. The effect of composition on the phase morphology of blend films when graphite is used as a substrate is also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3496–3504, 2004
The ‘Business’ of Quality Assurance
Authors: Grunbaum Len
Published: August 2004

This article will address how a quality assurance function (QA) can and should be a value to the business. QA represents a Management control; it is, or should be, the business instrument by which management is advised as to the status of regulatory compliance. And regulatory compliance is a business issue – make no mistake about it. But QA does not always discharge its responsibilities or perform its activities in a manner that truly serves the business purposes. The article examines some of the common scenarios in the industry, which are ‘sin‐dromes’ because they can result in increased business expenses and reduced profitability, and thus they are business ‘sins’. Copyright © 2004 John Wiley & Sons, Ltd.
Standard operating procedures for clinical research personnel ‐ Part 21
Authors: Bohaychuk Wendy , C.D. Graham Ball
Published: August 2004

This is the 21st in a series of articles containing proposals for wording and content of standard operating procedures (SOPs) for clinical research activities conducted by sponsors and Contract Research Organisations (CROs). The procedures include those required by the International Conference on Harmonisation (ICH), the Food and Drug Administration (FDA), many other guidelines and regulations, and ‘best practice’ observed by the authors. The model forms require modification for actual use. In this article, SOPs are presented for management of safety events: recording and reporting serious adverse events (SOP 603); and reporting safety information externally (SOP 604). (The full text of all 101 SOPs is available from the authors.) Copyright © 2004 John Wiley & Sons, Ltd.
cGMP violations may be the basis for QUI TAM lawsuits in the United States
Authors: Nolan Kenneth J.
Published: August 2004

Pharmaceutical manufacturers continue to battle with the Food and Drug Administration (FDA) over compliance with current Good Manufacturing Practice regulations (cGMP), which outline the requirements that drug manufacturers must follow for the manufacture, processing, packing, and holding of a drug. Pharmaceutical manufacturers have already been the target of successful Federal False Claims Act (FCA) prosecutions, mostly due to pricing and kickback issues raised in qui tam lawsuits. Qui tam lawsuits are brought under the FCA by private citizens who sue on behalf of the United States (US). In exchange for their efforts, the US law provides that the private citizen is entitled, generally, to 15 to 30 % of the recovery generated by the qui tam lawsuit.

Kenneth J. Nolan, a top qui tam attorney says that in the last several years, total payouts by manufacturers to settle qui tam lawsuits have amounted to over USD 2.0 billion. Copyright © 2004 John Wiley & Sons, Ltd.
Data quality of the clinical trial process – costly regulatory compliance at the expense of scientific proficiency
Authors: Lörstad Mats
Published: August 2004

The reasons for the belief in the need for perfection of clinical data are carefully nursed myths. The logical shortcomings in Good Clinical Practice are nothing but embarrassing to its scientifically trained promoters. Modern quality management methods, which increasingly degrade the importance of inspections, are described and their application in clinical research recommended. The documentation of procedures to attain acceptable quality levels of trial data is suggested to be standardized into a Quality Declaration. Copyright © 2004 John Wiley & Sons, Ltd.
Efficient evaluation of the molecular auxiliary function Bn by downward recursion
Authors: Harris Frank E.
Published: August 2004

It is known that the molecular auxiliary function Bn(q) can be generated stably by downward recurrence for the range n > |q|, but doing so requires a starting value of BN, where N is the largest n value needed. The question of the choice of upward vs. downward recursion is revisited. Then, it is shown that by writing BN(q) in terms of incomplete gamma functions and introducing an asymptotic expansion for the latter the necessary starting values can be obtained far more rapidly than heretofore for a significant range of |q| and N. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Relative energies, stereoelectronic interactions, and conformational interconversion in silacycloalkanes
Authors: Freeman Fillmore , Fang Christine , Shainyan Bagrat A.
Published: August 2004

Stereoelectronic hyperconjugative interactions, geometrical parameters, and relative energies of conformations and isomers of silacycloalkanes have been calculated at the B3LYP/6‐311+G(d,p) level of theory. The chair conformer of silacyclohexane was calculated to be 3.89, 4.82, and 5.18 kcal/mol more stable than the respective 1,4‐twist conformer, 2,5‐twist conformer, and 2,5‐boat transition state. Intrinsic reaction path (IRC) calculations connected the half‐chair transition state to the chair and 2,5‐twist conformers of silacyclohexane. The energy difference (ΔE) between the chair conformer and the half‐chair transition state that connects the chair conformer and 2,5‐twist conformer of silacyclohexane is 5.47 kcal/mol. The chair conformer of equatorial 1‐methyl‐1‐silacyclohexane is 0.45 kcal/mol more stable than the chair conformer of axial 1‐methyl‐1‐silacyclohexane. Axial 1‐methyl‐1‐silacyclohexane is 3.53 and 4.67 kcal/mol more than its 1,4‐twist and 2,5‐twist conformers, and equatorial 1‐methyl‐1‐silacyclohexane is 3.97 and 4.82 kcal/mol more stable than its 1,4‐twist and 2,5‐twist conformers. 1‐Silabicyclo[2.2.1]heptane is 4.58 and 10.8 kcal/mol, respectively more stable than 2‐silabicyclo[2.2.1]heptane and 7‐silabicyclo[2.2.1]heptane. The influences of selectively replacing a CH2group in a cycloalkane with a SiH2group on the geometrical parameters, conformational properties, ring strain, and stereoelectronic hyperconjugative interactions are discussed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Analysis of stock management gaming experiments and alternative ordering formulations
Authors: Barlas Yaman , Özevin Mehmet Günhan
Published: August 2004

This paper investigates two different yet related research questions about stock management in feedback environments. The first purpose is to analyse the effects of selected experimental factors on the performances of subjects (players) in a stock management simulation game. In light of these results, our second objective is to evaluate the adequacy of standard decision rules typically used in dynamic stock management models and to seek improvement formulations. To carry out the research, the generic stock management problem is chosen as the interactive gaming platform. In the first part, gaming experiments are designed to test the effects of three factors on decision‐making behaviour: different patterns of customer demand, minimum possible order decision (‘review’) interval and, finally, the type of receiving delay. ANOVA results of these three‐factor, two‐level experiments show which factors have significant effects on 10 different measures of behaviour (such as max–min range of orders, inventory amplitudes, periods of oscillations and backlog durations). In the second phase of research, the performances of subjects are compared against some selected ordering heuristics (formulations). First, the patterns of ordering behaviour of subjects are classified into three basic types. Comparing these three pattern types with simulation results using different decision rules, we observe that the common linear ‘anchoring and adjustment rule’ can represent the smooth and gradually damping type of behaviour, but cannot generate the non‐linear and/or discrete ordering dynamics. Thus, several alternative non‐linear rules are formulated and tested against subjects' behaviour patterns. Some standard discrete inventory control rules (such as (s, S)) common in the inventory management literature are also formulated and tested. These non‐linear and/or discrete rules, compared with the linear stock adjustment rule, are found to be more representative of the subjects' ordering behaviour in many cases, in the sense that these rules can generate non‐linear and/or discrete ordering behaviours. Another major finding is the fact that the well‐documented oscillatory dynamic behaviour of the inventory is a quite general result, not just an artifact of the linear anchor and adjust rule. When the supply line is ignored or underestimated, large inventory oscillations result also with the non‐linear rules, as well as the standard inventory management rules. Furthermore, depending on parameter values, non‐linear ordering rules are more prone to yield unstable oscillations—even if the supply line is taken into account. Further methodological and experimental research questions are suggested. Copyright © 2004 John Wiley & Sons, Ltd.
Consumers' bounded rationality: the case of competitive energy markets
Authors: Dyner Isaac , Franco Carlos Jaime
Published: August 2004

The recent liberalization of the energy industry provides a challenge for understanding the decision‐making processes of the agents involved in their markets. In this new environment, it is of particular interest to investigate consumers' decisions with respect to energy efficiency for a range of purposes that include the assessment of government policy and traders' strategy intents. The neo‐classic methodologies reported in the literature generally make strong, and not evident, assumptions with respect to the decision‐making processes of end‐users, including: complete information, full rationality and lack of risk perception. In this paper, the concept of bounded rationality is incorporated, seeking alternative grounds to the traditional approaches. Against this background, we examine different sets of assumptions based on the concept ofrationally bounded energy useand propose policies that may reduce some of the apparent market failures. However, both these claims, as well as the proposed system dynamics models that intend to account for bounded rationality, need to be clearly justified. Here, we do this by indicating, explicitly and implicitly, how bounded rationality operates and what policies and strategies might be appropriate to remove some of the consumers' barriers when confronting decisions. The system dynamics models presented in this paper incorporate consumers' behaviour and alternative policies to assess their likely impact on society. Examples related to the penetration of fuels and lighting appliances are provided, to illustrate the approach. Copyright © 2004 John Wiley & Sons, Ltd.
A content and process view on bounded rationality in system dynamics
Authors: Größler Andreas
Published: August 2004

The paper reviews references to bounded rationality within the system dynamics literature. It is argued that so far the relation between bounded rationality and system dynamics has primarily been discussed from a ‘content’ perspective, that is, that boundedly rational decision making needs to be incorporated in the detail of system dynamics models because of the methodology's aspiration to represent real, not ideal decision making. In this paper this content view is extended by a new ‘process’ perspective. This perspective concerns effects observed at the level of whole models. For example, during modelling the developer of a system dynamics model is prone to be influenced by the limitations of rationality, which might lead to erroneous models. In the same way, users conducting simulation experiments with models are prone to carry out these simulations in an unsystematic way and might draw wrong conclusions from the simulation outcomes. The paper then outlines the connections between the established content view and the new process view on bounded rationality in system dynamics. These connections lie in the knowledge elicitation phase of modelling and in the changes of real systems on the basis of insights gained in modelling and simulation. The paper closes with a brief statement of the research that the author is conducting with a view to exploring further these ideas. Copyright © 2004 John Wiley & Sons, Ltd.
Exploring influencing factors on rationality: a literature review of dynamic decision‐making studies in system dynamics
Authors: Rouwette Etiënne A. J. A. , Größler Andreas , Vennix Jac A. M.
Published: August 2004

Simulators and experiments studying dynamic decision making offer a way of finding out about factors enforcing and inhibiting human rationality. This literature review of 51 studies from the system dynamics field helps to identify various factors that influence decision making. The factors are classified into model, simulator and player characteristics. In the paper the effect of these variables on gaming performance is reviewed and synthesized. Model characteristics such as presence of delay and increase of feedback strength seem to lower performance, while changes in exogenous conditions lead to mixed results. With regard to simulator characteristics, the decision interval does not seem to influence performance. Model transparency has a positive relation to performance, similar to decision information (in conjunction with player characteristics). Lastly, with regard to player characteristics, there is some evidence that a long‐term goal increases performance. Although problem‐solving style and mental model characteristics impact performance, no relation between general personality types and performance is found. Also, there are no consistent differences between individuals and pairs with regard to performance. The paper closes with brief comments on future research directions. Copyright © 2004 John Wiley & Sons, Ltd.
Methodologies in conflict: achieving synergies between system dynamics and organizational cybernetics
Authors: Schwaninger Markus
Published: August 2004

Coping with complexity is at the heart of the systems approach. Several methodologies can be discerned which have proved to possess extraordinary power in dealing with complex issues. System dynamics is a general‐purpose methodology for modelling and simulation employed in order to deal with dynamic complexity. Cybernetics has brought forth structural models to enable organizations to deal with the complexity of their environments. The main proposition of this paper is that these two methodological strands show potential synergies. A proposal for leveraging the complementarities of system dynamics and organizational cybernetics is made. The paper also argues that it is necessary to conflate qualitative and quantitative modelling and design approaches, as well as to improve the quality of models and strategies by strengthening the processes of validation. At a higher level of abstraction, the author postulates that, for the sake of relevance, this methodological synthesis is to build upon both the positivist and interpretivist traditions. On this basis, a framework called integrative systems methodology is proposed to help actors at different levels to achieve the requisite variety. Copyright © 2004 John Wiley & Sons, Ltd.
Cis‐trans Isomerism in Copper(II) Complexes with N‐acyl Thiourea Ligands
Authors: Hernández Wilfredo , Spodine Evgenia , Vega Andres , Richter Rainer , Griebel Jan , Kirmse Reinhard , Schröder Uwe , Beyer Lothar
Published: August 2004

The N‐acyl thiourea complexes bis[N,N‐diethyl‐N′‐(p‐nitrobenzoyl)‐thioureato]copper(II) (1a,1b) and bis(N,N‐diphenyl‐N′‐benzoylthioureato)copper(II) (2a,2b) crystallize in each case in two modifications. X‐ray structural analysis shows that 1a and 1b are cis‐trans isomers. This is very unusual for N‐acyl thioureato complexes because with exception of one platinum(II) complex up to now only cis complexes have been found. In contrast X‐ray structural analysis of both forms 2a and 2b of the other complex shows no cis‐trans pair. Both modifications are cis complexes. In solution both isomers of the copper(II) complexes are observable by EPR spectroscopy.
Triphenylphosphinimino‐triphenylstiboniumchlorid, [Ph3PNSbPh3Cl], und seine Reaktion mit FeCl3
Authors: Neumüller Bernhard , Dehnicke Kurt
Published: August 2004

[Ph3PNSbPh3Cl] (1) was prepared by oxidative addition of ClNPPh3 to triphenylstibine in dichloromethane solution. The compound is characterized by IR spectroscopy and by an X‐ray structure determination. 1 crystallizes in the monoclinic space group P21/c with four formula units per unit cell. Lattice dimensions at 193 K: a = 925.3(1), b = 1777.2(1), c = 1825.5(1) pm, β = 94.07(1)°, R1 = 0.0228. 1 forms monomeric molecules with tetrahedrally coordinated phosphorus and trigonal‐bipyramidally coordinated antimony atom, the atoms N and Cl being in axial positions. The bond lengths PN and SbN are 155.0(2) and 198.4(2) pm, respectively, the PNSb angle is 138.6(1)°. 1 reacts with iron trichloride to give the known phosphoraneiminato complex [FeCl2(NPPh3)]2.
Die Kristallstruktur von (Ph4P)2[Be4Cl4(μ‐N3)6]
Authors: Neumüller Bernhard , Dehnicke Kurt
Published: August 2004

Suitable single crystals for X‐ray analysis of the recently published azido beryllate (Ph4P)2[Be4Cl4(μ‐N3)6] (1) [1] were obtained by a modified synthetic route, and the crystal structure of 1 was determined. The compound crystallizes isotypically with the corresponding bromo derivative [1] in the space group C2/c with 12 formula units per unit cell. Lattice dimensions at 193 K: a = 4125.5(1), b = 2001.7(1), c = 2050.4(1) pm, β = 101.05 (1)°, R1 = 0.0359. The structure contains adamantanlike dianions [Be4Cl4(μ‐N3)6]2− with a Be4N6 core forming by the bridging function of the α‐nitrogen atoms of the azido groups.
Natriumkomplexe mit Salicylideniminen: Synthesen, Strukturen, CO2‐Aufnahme und Carboxylierung von 2‐Fluorpropiophenon bzw. Estronmethylether
Authors: Fischer Reinald , Görls Helmar , Walther Dirk
Published: August 2004

Chirale Salicylidenphenethylamine (R)‐HA, oder (S)‐HA, 2‐Salicylidenfurfurylimin HB und 2‐Salicylidenaminoethanol HC reagieren mit Natriumhydrid oder Natrium‐hexamethyldisilylamid zu den Natriumkomplexen [Na(R)‐A]4 · 0,5 Et2O, [Na(S)‐A]4 · 0,5 Et2O (1), [NaB]4 · 0,5 Ph‐Me (2) und [(dme)NaC]4 (3). In Gegenwart von 18‐Krone‐6 lässt sich auch der Komplex [Na(18‐Krone‐6)(thf)2]2[Na2(C)]4 · THF (4) isolieren. Kristallstrukturanalysen weisen für 1 und 2 aus, dass Heterocubanstrukturen mit einem Na4O4‐Grundgerüst ausgebildet werden. Außerdem ist das Iminstickstoffatom an Na gebunden, das in 1 die Koordinationszahl vier hat. Durch zusätzliche Koordination des Furfurylsauerstoffatoms erreicht Na in 2 die Koordinationszahl 5. Im ebenfalls tetrameren 3 werden zwei Na2O2‐Einheiten über zwei Imino‐ethanolbrücken Na(1)‐N(=CH‐Phenolat)‐CH2CH2‐OH‐Na(2A) miteinander verbunden. Die Kristallstrukturanalyse zeigt, dass 4 eine ionische Verbindung ist, die aus zwei [(thf)2Na(18‐Krone‐6)]+‐Kationen und dem dinuklearen Dianion [Na2(C)4]2− besteht. 1 und 2 sind Carboxylierungsreagenzien, die CO2 auf 2‐Fluorpropiophenon übertragen. 1 ist aktiver als 2, während 3 und 4 inaktiv sind.
[CoIICuI2(Im)4];∞: A Layered Bimetallic Imidazolate Polymer, the First Hybridized Cobalt(II) Imidazolate
Authors: Tian Yun‐Qi , Xu Hai‐Jun , Li Yi‐Zhi , You Xiao‐Zeng
Published: August 2004

A 2D grid‐shaped bimetallic imidazolate polymer [CoIICuI2(Im)4];∞ (1) was solvothermally synthesized and characterized with single crystal X‐ray analysis: tetragonal space group P$\bar 4$21/c (No.114), a = b = 10.9513(15) Å, c = 6.3063(13) Å, V = 756.3(2) Å3. This is the first cobalt(II) imidazolate polymer hybridized with other transition metals.
3D Coordination Polymer Incorporating Discrete Molecular Octahedra
Authors: Komarchuk Vasiliy V. , Ponomarova Vira V. , Krautscheid Harald , Domasevitch Konstantin V.
Published: August 2004

Copper(II) oxalate coordination polymer [{Cu4(C2O4)4(L)4}3 · {Cu3(C2O4)3(L)6}2 · 3L · 25H2O]n (L = 3,3′,5,5′‐tetramethyl‐4,4′‐bipyrazole) reveals a structure that is related to the Pt3O4 net topology. The 3D linkage is sustained with copper‐oxalate squares and copper‐bipyrazole triangles sharing vertices. The framework supports giant icosahedral cages and entraps discrete molecular octahedra formed by two molecular complexes Cu3(C2O4)3(L)6 associated by means of NH‐‐‐N hydrogen bonding. The coexistence of the discrete and 3D portions formed by the same components suggests self‐templation as a key feature of the system. Simpler copper oxalate compounds [Cu(C2O4)(L)2(H2O)] · CH3OH · 3.75H2O and [Cu2(C2O4)2(L)5] · L · 11H2O are concomitant products of the reaction mixture and they exist in the form of molecular mono‐ and binuclear complexes.
X‐Ray Investigations of the intrinsic Carbon‐Incorporation during the MOVPE Growth of AlxGa1‐xAs
Authors: Gottschalch Volker , Leibiger G. , Spemann D.
Published: August 2004

We have investigated the intrinsic C‐incorporation during the metalorganic vapour‐phase epitaxy of GaAs, (Al,Ga)As, and AlAs. The carbon from the methyl radicals of trimethylgallium and trimethylaluminium has been used as intrinsic carbon source and the necessary growth conditions (low growth temperatures and low V/III‐ratios) have been determined. Under these conditions we observed a reduction of the Al‐incorporation in (Al,Ga)As resulting from a change of surface kinetics at low temperatures. We have used the tensile tetragonal lattice distortion due to the C‐incorporation for determination of the carbon concentration. This has been done by investigating the symmetric (004) reflection peaks of GaAs and the strained epitaxial layer by high resolution x‐ray diffraction. The resulting carbon concentrations showed a good agreement with the hole concentrations determined by Hall measurements and spectroscopic ellipsometry.
Synthesis and Structures of Yb4Rh7Ge6 and Yb4Ir7Ge6
Authors: Heying Birgit , Katoh Kenichi , Niide Yuzuru , Ochiai Akira , Pöttgen Rainer
Published: August 2004

Larger single crystals of Yb4Rh7Ge6 and Yb4Ir7Ge6 were prepared from arc‐melted precursor alloys Rh7Ge6 and Ir7Ge6 and elemental ytterbium via the Bridgman method using tungsten crucibles. Yb4Rh7Ge6 and Yb4Ir7Ge6 were investigated by X‐ray diffraction on powders and single crystals. Both germanides crystallize with the cubic U4Re7Si6 type structure, space group Im3m. Structure refinement from X‐ray single crystal diffractometer data yielded a = 825.3(1) pm, wR2 = 0.0292, 106 F2 values, 10 variable parameters for Yb4Rh7Ge6 and a = 826.6(2) pm, wR2 = 0.0486, 150 F2 values, 10 variable parameters for Yb4Ir7Ge6. The structures contain two crystallographically independent transition metal (T) atoms with octahedral (T1) and tetrahedral (T2) germanium coordination. The octahedra and tetrahedra are condensed via common corners and edges forming complex three‐dimensional [T7Ge6] networks in which the trivalent ytterbium atoms fill voids of coordination number 14.
(n‐Bu4N)2[Au(mnt)2]: Synthese, Struktur‐ und EPR‐Untersuchungen eines stabilen, mononuklearen AuII‐Komplexes
Authors: Kirmse R. , Kampf M. , Olk R.‐M. , Hildebrand M. , Krautscheid H.
Published: August 2004

Die Reaktion von [AuIII(mnt)2]− mit (n‐Bu4N)[BH4] in Aceton führt zur Bildung des bisher zweiten stabilen mononuklearen AuII‐Komplexes [AuII(mnt)2]2− dessen Struktur erstmals aufgeklärt werden konnte. (n‐Bu4N)2[AuII(mnt)2] kristallisiert triklin, P$\bar 1$ (a = 904,24(5), b = 989,55(5), c = 1627,35(10) pm, α = 92,040(7), β = 94,937(7), γ = 107,220(6)°, Z = 1) mit zwei Acetonmolekülen pro Elementarzelle. Das Anion ist planar. EPR‐Untersuchungen an Einkristallen von (n‐Bu4N)2[AuII(mnt)2] gestatten Aussagen zur Anisotropie des g‐Tensors und über die Linienbreitenanalyse Aussagen zu magnetischen Austauschwechselwirkungen.
The New Polar Intermetallic Compound NaBaBi
Authors: Hirt Holger , Deiseroth Hans‐Jörg
Published: August 2004

Small lamellar air sensitive crystals of NaBaBi with a blue metallic lustre were obtained by direct reaction of the elements. The new polar intermetallic compound, which can formally be described as Na+Ba2+Bi3− crystallizes isotypic to Fe2P with lattice constants a = 859.1(1) pm, c = 509.1(1) pm (Z = 3, P $\bar 6$2m). NaBaBi is a small gap semiconductor similar to pnictides of the type A3B (A: alkali metal, B: Sb) and thus is a potential candidate for photoelectric applications.
μ‐Oxo‐bis[(cyclopentadienyl)(η1‐η1‐1,1,2,3,4,4‐hexafluorbut‐2‐en‐1,4‐diyl)mangan(IV)] – Ein höher valenter Organometall‐Mangan‐Komplex
Authors: Lentz Dieter , Akkerman Floris , Kickbusch Rainer , Patzschke Mona
Published: August 2004

Photochemical substitution of two carbonyl ligands of tricarbonyl(η5‐cyclopentadienyl)manganese by the butadienes, hexafluorobuta‐1,3‐diene (1a), 1,1,2,4,4‐pentafluorobuta‐1,3‐diene (1b), 1,1,4,4‐tetrafluorobuta‐1,3‐diene (1c), 1,1,2‐trifluorobuta‐1,3‐ diene (1d) und 1,1‐difluorobuta‐1,3‐diene (1e) yields the correspond‐ ing half sandwich complexes carbonyl (η4‐butadiene) (η5‐cyclopentadienyl)manganese (2a‐e), respectively. According to the IR spectrum of 2a‐e, the π acceptor strength increases with the number of fluorine atoms within the ligands 1a‐e. 2a reacts with oxygen at ambient temperature forming μ‐oxo‐bis[(cyclopentadienyl)(η1‐η1‐1,1,2,3,4,4‐hexafluorobut‐2‐en‐1,4‐diyl)manganese(IV)] (3). The structures of 2a, 2c and 3 were elucidated by X‐ray crystallography demonstrating the difference in coordination of the butadiene ligands.
Stanna‐closo‐dodecaborate: A New Ligand in Coordination Chemistry
Authors: Wesemann Lars
Published: August 2004

Most of the divalent compounds of tin have a lone pair and hence can act as donors. In tin‐transition metal chemistry neutral molecules as well as anions have been studied as ligands. This research report summarizes recent research on coordination compounds with a closo‐heteroborate cage compound stanna‐closo‐dodecaborate [SnB11H11]2−. The syntheses of the first coordination compounds and studies on the ligand abilities of this tin borate are discussed in this article.
The replication band of Euplotes is enriched with phosphoproteins
Authors: Olins Donald E. , Cacheiro Lucia H. , Herrmann Adria L.
Published: August 2004

Summary— Employing several antibodies to phosphorylated protein epitopes, we demonstrate by immunostaining that the macronuclear replication band (RB) of the ciliated protozoan Euplotes eurystomus contains a high concentration of phosphoproteins. Enrichment is principally within the rear zone of the RB, the region of DNA synthesis and chromatin assembly. By immunoblot analysis, the various antibodies reacted with a diversity of macronuclear phosphoproteins, one of which was phosphorylated histone Hl. This diversity of phosphoproteins was also supported by examination of the macronuclear matrix generated by high NaCl extraction. Available evidence clearly indicates that the ultrastructural wave of chromatin modulation accompanying DNA replication is spatially correlated with a wave of localized nuclear protein phosphorylation.
Analysis of centromere structure in the fly Megaselia scalaris (Phoridae, Diptera) using CREST sera, anti‐histone antibodies, and a repetitive DNA probe
Authors: Wolf Klaus Werner , Mitchell Arthur , Nicol Linda , Jeppesen Peter
Published: August 2004

We have used CREST anti‐centromere sera, rabbit anti‐histone antibodies, and repetitive DNA analysis to study centromere structure in the fly Megaselia scalaris (Phoridae). In a panel of eight CREST sera, four were positive in immunofluorescence experiments for prekinetochores, ie centromeres in interphase nuclei. The access of the antibodies to CREST antigens may be compromised in the condensed state, since centromeres of prometaphase and metaphase chromosomes remained unstained. When Western blots of embryonic nuclei were probed with these four CREST sera, three of them showed a 17 kDa band. Human CENP‐A, likewise recognized by the CREST sera, is a 17 kDa protein. The remaining sera were negative for centromeres although some detected centrosomes and non‐histone chromosomal proteins not confined to the centromeres. The use of antibodies generated against histone H4 acetylated at four different sites of the N‐terminal domain revealed that heterochromatic regions of M scalaris mitotic chromosomes, ie pericentric and NOR‐associated segments, are hyperacetylated. This is at variance with a variety of other systems, where transcriptionally active chromatin is hyperacetylated. Finally, a repetitive 165 base pair fragment was isolated from genomic DNA of the fly and sequenced. An oligonucleotide from this sequence mapped to the centromere region of interphase nuclei and the pericentric regions of condensed chromosomes.
Tissular distribution of heteroplasmy and ultrastructural studies of mitochondria from a Drosophila subobscura mitochondrial deletion mutant
Authors: Lecher Pierre , Béziat Florence , Alziari Serge
Published: August 2004

A mutant strain of Drosophila subobscura possesses two mitochondrial genome types: a minority population (20%) identical to the wild strain mtDNA (15.9 kb), and a largely predominant population (80%) of shorter genomes (10.9 kb), presenting a deletion of more than 30% of its coding region. Study of tissular distribution of heteroplasmy shows it to be identical — about 80% — in the head (nervous tissue) and thorax (muscles). On the other hand, a lower percentage (64%) is observed in the ovaries. The strain is apparently unaffected despite this massive loss of genes, coding for four tRNA and for complex I and III subunits. Contrary to observations of similar situations in man, the mutant strain shows no accumulation or structurally abnormal mitochondria. Furthermore, cytochemical studies fail to detect mitochondria devoid of cytochrome oxidase activity (COX−). Finally, mitoribosome populations are identical in mitochondria from both strains. These results suggest that, in the mutant strain, there are no mitochondria containing deleted genomes only: heteroplasmy would thus be intramitochondrial.
The platinum‐carbon replication of a homogenous population of gold particles makes log‐normal distributions of shadow widths and lengths
Authors: Péranzi Gabriel , Bayle Denis , Telford John N. , Thomas‐Soumarmon Annick
Published: August 2004

Gold particles were prepared, dried on grids and shadowed at 45° with a 1.2 nm platinum‐carbon (Pt‐C) film using the shadowing conditions previously described for the freeze‐fracture of gastric parietal cell membranes. The particle diameters and the particle shadow widths and lengths were measured using an image analysis system. Statistical analysis of 2000 diameters, shadow widths and shadow lengths indicated that a homogenous population of particles had a normal frequency distribution of diameters (mean diameter 14.5 ± 1.5 nm) and that the Pt‐C shadowing transformed that normal curve into a log‐normal frequency distribution of shadow widths. The frequency distribution of shadow lengths was log‐normal too. We conclude that a statistical partition of experimental frequency distributions of particle shadow widths and lengths of natural membranes to determine the number and parameters of individual components should involve log‐normal subdistributions rather than normal ones.
A SEM analysis of DMSO treated hydra polyps
Authors: Bolzer Andreas , Melzer Roland R. , Bosch Thomas C.G
Published: August 2004

Summary— Scanning electron microscopy revealed that exposure of hydra polyps to DMSO at concentrations used for permeabilizing tissue results in striking changes in epithelial cell morphology. Epithelial cells from treated polyps rounded up in shape and formed numerous large blebs at the cell surface. Along the borders of epithelial cells numerous small projections became detectable. The DMSO‐induced changes at the cell surface corresponded to drastic changes in the intracellular organization. No evidence could be found for DMSO induced opening of cell junctions and/or opening of the interstitial space. The results demonstrate that DMSO affects the morphology and intracellular organization of hydra epithelial cells. Thus, caution is necessary in interpreting cell behavior in DMSO treated tissue.
The nucleolus and transcription of ribosomal genes
Authors: Raška Ivan , Koberna Karel , Malínský Jan , Fidlerová Helena , Mašata Martin
Published: August 2004

Abstract Ribosome biogenesis is a highly dynamic, steady‐state nucleolar process that involves synthesis and maturation of rRNA, its transient interactions with non‐ribosomal proteins and RNPs and assembly with ribosomal proteins. In the few years of the 21st century, an exciting progress in the molecular understanding of rRNA and ribosome biogenesis has taken place. In this review, we discuss the recent results on the regulation of rRNA synthesis in relation to the functional organization of the nucleolus, and put an emphasis on the situation encountered in mammalian somatic cells.