bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Efficient Disproportionation of Dihydrogen Peroxide: Synthesis, Structure, and Catalase Activity of Manganese Complexes of the Salicylimidate Ligand
Authors: Godbole Meenal D. , Kloskowski Michael , Hage Ronald , Rompel Annette , Mills Allison M. , Spek Anthony L. , Bouwman Elisabeth
Published: November 2004

Two complexes, [Mn2(etsalim)4(Hetsalim)2](ClO4)2 (1), and [Mn(mesalim)2(OAc)(MeOH)]·MeOH (2), in which Hmesalim and Hetsalim are methyl and ethyl salicylimidate, respectively, have been synthesized, fully characterized by X‐ray analyses, magnetic susceptibility, UV/Vis and IR spectroscopy, and their catalase activity has been studied. Complex 1 is dinuclear and shows an Mn−Mn distance of 3.37 Å while complex 2 is mononuclear. Both complexes catalyze the disproportionation of hydrogen peroxide into water and dioxygen; they show very high catalase activity exhibiting saturation kinetics in the presence of NaOH. The rate and turnover number of the catalyzed reaction increase dramatically when a few equivalents of base (NaOH) are added to the reaction mixture. The turnover numbers for hydrogen peroxide disproportionation increase from approximately 200 to more than 1500 per manganese ion in less than 2 min for both complexes after addition of a few equivalents of NaOH. Kinetic studies of the catalyzed reaction performed on the dinuclear complex 1 in the presence of 5 equiv. of NaOH, gives kcat = 807 s−1 (± 16) and KM = 0.091 M (± 0.003). The effective catalytic efficiency is kcat/KM = 8900 M−1s−1. The kinetic parameters of the mononuclear complex 2 in the presence of 5 equiv. of NaOH, are kcat = 190 s−1 (± 4) and KM = 0.022 M (± 0.001). The effective catalytic efficiency is kcat/KM = 8600 M−1s−1. The catalase activity of the mononuclear complex, [Mn(mesalim)2Cl] (3) has also been studied, and it shows turnover numbers that are comparable to those of complex 2. ESI‐MS analyses in deuterated solvents have been used to understand the nature of the active species formed on addition of 5 equiv. of NaOH. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Studies of the Nature of the Catalytic Species in the α‐Olefin Polymerisation Processes Generated by the Reaction of Diamido(cyclopentadienyl)titanium Complexes with Aluminium Reagents as Cocatalysts
Authors: Tabernero Vanessa , Cuenca Tomás
Published: November 2004

The reaction of the diamido(chloro)cyclopentadienyltitanium compounds TiCpRx[1,2‐C6H4(NR′)2]Cl [CpRx = η5‐C5H5, η5‐C5(CH3)5, η5‐C5H4(SiMe3); R′ = CH2tBu, Pr] with the Grignard reagent MgClR (R = Me, CH2Ph) affords the monomethyl and monobenzyl derivatives TiCpRx[1,2‐C6H4(NR′)2]R. Upon addition of methylaluminoxane (MAO), the chloro‐ and alkyltitanium complexes show low activity towards the polymerisation of ethylene and styrene. However, no methylation was observed during the treatment of trimethylaluminium with the chloro compounds TiCpRx[1,2‐C6H4(NR′)2]Cl. Instead, these reactions give the dinuclear aluminium complexes Al2[1,2‐C6H4(NR′)2]Me4 (R′ = CH2tBu, Pr) through transmetallation of the diamido ligand, suggesting a deactivation process of the catalysts in the olefin polymerisation reactions. In an additional effort to model the catalytic species, stoichiometric reactions between the methyl derivatives TiCpRx[1,2‐C6H4(NR′)2]Me and solid methylaluminoxane (MAO) were studied by NMR spectroscopy. Monitoring of these reactions revealed the formation of zwitterionic species depending on the nature of the solvent. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Prevalence of Hepatic Steatosis in An Urban Population in the United States: Impact of Ethnicity
Authors: Browning Jeffrey D. , Szczepaniak Lidia S. , Dobbins Robert , Nuremberg Pamela , Horton Jay D. , Cohen Jonathan C. , Grundy Scott M. , Hobbs Helen H.
Published: November 2004

Despite the increasing prevalence of nonalcoholic fatty liver disease (NAFLD), its pathogenesis and clinical significance remain poorly defined. In this study, we examined and compared the distribution of hepatic triglyceride content (HTGC) in 2,287 subjects from a multiethnic, population–based sample (32.1% white, 48.3% black, and 17.5% Hispanic) using proton magnetic resonance spectroscopy. HTGC varied over a wide range (0.0%–41.7%; median, 3.6%) in the population. Almost one third of the population had hepatic steatosis, and most subjects with hepatic steatosis had normal levels of serum alanine aminotransferase (79%). The frequency of hepatic steatosis varied significantly with ethnicity (45% in Hispanics; 33% in whites; 24% in blacks) and sex (42% in white men; 24% in white women). The higher prevalence of hepatic steatosis in Hispanics was due to the higher prevalence of obesity and insulin resistance in this ethnic group. However, the lower frequency of hepatic steatosis in blacks was not explained by ethnic differences in body mass index, insulin resistance, ethanol ingestion, or medication use. The prevalence of hepatic steatosis was greater in men than women among whites, but not in blacks or Hispanics. The ethnic differences in the frequency of hepatic steatosis in this study mirror those observed previously for NAFLD–related cirrhosis (Hispanics > whites > blacks).

In conclusion

, the significant ethnic and sex differences in the prevalence of hepatic steatosis documented in this study may have a profound impact on susceptibility to steatosis–related liver disease. (Hepatology 2004;40:1387-1395.)
Randomized Trial of Leuprorelin and Flutamide in Male Patients With Hepatocellular Carcinoma Treated With Tamoxifen
Authors: Trinchet Jean–Claude
Published: November 2004

The growth of hepatocellular carcinoma (HCC) is thought to be dependent on androgens, as androgen receptors are present in most of these tumors. The aim of this multicenter trial was to assess the effect of antiandrogens in patients who have advanced HCC. Male patients with advanced HCC were randomized into 2 groups treated with (1) leuprorelin (3.75 mg/mo subcutaneously), flutamide (750 mg/d orally), and tamoxifen (30 mg/d orally) or (2) tamoxifen alone (30 mg/d orally) administered until death. Survival was the main end point (log–rank test). The required sample size was 375 patients (alpha, 5%; beta, 10%; 1–year survival, 45% in treated group and 30% in controls). Between February 1994 and January 1998, 376 male patients (mean age, 66 years; treated group, n = 192; control group, n = 184) were included. No baseline imbalance was found between the groups. At the reference date (January 1, 2003), 183 deaths (95.3%) were observed in the treated group and 177 deaths (96.2%) were observed in controls. Thirteen patients were lost to follow–up. Median survival time was estimated to be 135.5 days (95% CI, 112–189) and 176 days (95% CI, 141–227) in treated and control groups, respectively (

P

= .21). Crude and adjusted relative risks of death in the treated group were estimated at 1.14 (95% CI, 0.93–1.40) and 1.08 (95% CI, 0.87–1.33;

P

= .48) respectively. Premature interruption of treatment was more frequent in the treated group (n = 45) than in controls (n = 22;

P

= .0045), mainly because of digestive side effects.

In conclusion

, no benefit in survival was found with antiandrogenic treatment in male patients with advanced HCC. (Hepatology 2004;40:1361-1369.)
On the Scope of a Prins‐Type Cyclization of Oxonium Ions
Authors: Fráter Georg , Müller Urs , Kraft Philip
Published: November 2004

The Prins cyclization of an aldehyde 1 with a homoallylic alcohol 2, affording tetrahydro‐2H‐pyrans 4 via the oxonium ion 3 as central intermediate, was conceptually transferred to (alk‐3‐enyloxy)acrylates 6, which form a related oxonium ion 7 upon treatment with acids (Scheme 1). The scope and utility of this modification of the Prins‐type cyclization of oxonium ions is discussed exemplarily by means of the syntheses of ten tetrahydro‐2H‐pyran and tetrahydrofuran derivatives, featuring diverse substitution patterns as well as different degrees of molecular complexity. These target structures include (±)‐ethyl (2RS)‐2‐[(2RS,4SR,6RS)‐ and (2SR,4RS,6SR)‐2‐tetahydro‐4‐hydroxy‐6‐methylpyran‐2‐yl]propanoate (23), (±)‐ethyl [(2RS, 3RS)‐tetrahydro‐3‐isopropenylfuran‐2‐yl]acetate (32), (±)‐ethyl (2Z)‐3‐(tetrahydro‐2,2‐dimethylfuran‐3‐yl)acrylate (37), (±)‐(3aRS,6RS, 7aRS)‐octahydro‐7a‐methylbenzofuran‐6‐yl formate (42), (±)‐ethyl (2RS,3RS,4aRS,8SR,8aRS)‐hexahydro‐2,5,5,8‐tetramethyl‐7‐oxo‐2H,5H‐pyrano[4,3‐b]pyran‐3‐carboxylate (48), and (±)‐ethyl (2RS,3RS,6SR)‐tetrahydro‐6‐(2‐methoxy‐2‐oxoethyl)‐3‐methyl‐2H‐pyran‐2‐carboxylate (53) (see Schemes 3 and 5–8). Besides the stereochemistry and mechanistic details of this versatile oxonium‐ion cyclization, the synthesis of suitable starting materials is also described.
Fluorous‐Silica‐Supported Perfluoro‐Tagged Palladium Complexes Catalyze Suzuki Couplings in Water
Authors: Tzschucke Carl Christoph , Bannwarth Willi
Published: November 2004

Different Pd‐complexes (see 2a–d and 3) with and without perfluoroalkyl tags were deposited on fluorous reversed‐phase silica 1 and unmodified silica gel. These supported complexes were successfully used as precatalysts for the Suzuki reaction in H2O. H2O‐Soluble aryl bromides were easily converted to the corresponding biphenyls. Although none of the complexes is H2O‐soluble, the active catalyst is most likely homogeneously dissolved. Nevertheless, the Pd‐leaching into the product was low.
Menverins A–D, New Highly Oxygenated Guaiane Lactones from Hainan Gorgonian Menella verrucosa (Brundin)
Authors: Zhang Wen , Guo Yue‐Wei , Mollo Ernesto , Cimino Guido
Published: November 2004

Four new highly oxygenated guaiane lactones, menverins A–D (1–4), were isolated from the gorgonian Menella verrucosa (Brundin) from the South China Sea. Their structures and relative configurations were elucidated on the basis of spectroscopic data. All compounds contain a conjugated α‐methyl‐substituted α, β‐unsaturated γ‐lactone moiety, a C(8)C(9) conjugated with the γ‐lactone moiety, and an exocyclic methylene group at C(4) (trivial numbering).
A New Iterative Approach for the Synthesis of Oligo(phenyleneethynediyl) Derivatives and Its Application for the Preparation of FullereneOligo(phenyleneethynediyl) Conjugates as Active Photovoltaic Materials
Authors: Nierengarten Jean‐François , Gu Tao , Hadziioannou Georges , Tsamouras Dimitris , Krasnikov Victor
Published: November 2004

Disymmetrically substituted oligo(phenyleneethynediyl) (OPE) derivatives were prepared from 2,5‐bis(octyloxy)‐4‐[(triisopropylsilyl)ethynyl]benzaldehyde (5) by an iterative approach using the following reaction sequence: i) Corey–Fuchs dibromoolefination, ii) treatment with an excess of lithium diisopropylamide, and iii) a metal‐catalyzed cross‐coupling reaction of the resulting terminal alkyne with 2,5‐diiodo‐1,4‐bis(octyloxy)benzene (3) (Schemes 2 and 3). Reaction of the OPE dimer 8 and trimer 13 thus obtained with N‐methylglycine and C60 in refluxing toluene gave the corresponding C60OPE conjugates 16 and 17, respectively (Scheme 4). On the other hand, treatment of the protected terminal alkynes 8 and 13 with Bu4N followed by reaction of the resulting 9 and 14 with 4‐iodo‐N,N‐dibutylaniline under Sonogashira conditions yielded 10 and 15, respectively (Schemes 2 and 3). Subsequent treatment with N‐methylglycine and C60 in refluxing toluene furnished the C60OPE derivatives 18 and 19 (Scheme 4). Compound 9 was also subjected to a Pd‐catalyzed cross‐coupling reaction with 3 to give the centrosymmetrical OPE pentamer 20 (Scheme 5). Subsequent reduction followed by reaction of the resulting diol 21 with acid 22 under esterification conditions led to bis‐malonate 23. Oxidative coupling of terminal alkyne 14 with the Hay catalyst gave bis‐aldehyde 24 (Scheme 6). Treatment with diisobutylaluminium hydride followed by dicylcohexylcarbodiimide‐mediated esterification with acid 22 gave bis‐malonate 26. Finally, treatment of bis‐malonates 23 and 26 with C60, I2, and 1,8‐diazabicylco[5.4.0]undec‐7‐ene (DBU) in toluene afforded the bis[cyclopropafullerenes] 27 and 28, respectively (Scheme 7). The C60 derivatives 16–19, 27, and 28 were tested as active materials in photovoltaic devices. Each C60OPE conjugate was sandwiched between poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate)‐covered indium tin oxide and aluminium electrodes. Interestingly, the performances of the devices prepared from the N,N‐dialkylaniline‐terminated derivatives 18 and 19 are significantly improved when compared to those obtained with 16, 17, 27, and 28, thus showing that the efficiency of the devices can be significantly improved by increasing the donor ability of the OPE moiety.
Errors in pathology and laboratory medicine: Consequences and prevention
Authors: Hollensead Sandra C. , Lockwood William B. , Elin Ronald J.
Published: November 2004

Reducing errors and improving quality are an integral part of Pathology and Laboratory Medicine. The rate of errors is reviewed for the pre‐analytical, analytical, and post‐analytical phases for a specimen. The quality systems in place in pathology today are identified and compared with benchmarks for quality. The types and frequency of errors and quality systems are reviewed for surgical pathology, cytopathology, clinical chemistry, hematology, microbiology, molecular biology, and transfusion medicine. Seven recommendations are made to reduce errors in future for Pathology and Laboratory Medicine. J. Surg. Oncol. 2004;88:161–181. © 2004 Wiley‐Liss, Inc.
Adjuvant hepatic arterial infusion after curative resection of colorectal liver metastases using removable intra‐arterial catheters with shape‐memory alloy
Authors: Tono Takeshi , Kanoh Toshiyuki , Ohnishi Tadashi , Matsushita Masaki , Nakano Yoshiaki , Kimura Yutaka , Iwazawa Takashi , Yano Hiroshi , Okamura Jun , Monden Takushi
Published: November 2004

Background and Objectives

Although there are some reports that adjuvant hepatic arterial infusion (HAI) chemotherapy reduces the hepatic recurrence following curative resection of colorectal liver metastases, problems of indwelling catheters after chemotherapy cessation remains unsolved. The usefulness of adjuvant HAI was investigated using a removable port‐catheter system.

Methods

Spiral catheters™ were attempted to be placed in 17 patients who underwent curative hepatectomy. The catheter contains a special shape‐memory alloy at its tip, which allows stable fixation to the vascular wall without coiling so the catheter can be removed if necessary. 5‐fluorouracil (5‐FU) in total dose of 12 g was intra‐arterially administered.

Results

W spiral catheters™ were successfully placed in the hepatic artery by percutaneous approach in 82% of the patients. All patients underwent scheduled chemotherapy without serious adverse events. Reservoir‐catheter system was removed easily and uneventfully after discontinuation of the chemotherapy. 3D‐CT angiography revealed that the hepatic artery was well preserved with short‐term chemotherapy. Postoperative hepatic recurrence was observed only in 18% of the patients with the median follow‐up time of 19.9 months.

Conclusions

Prophylactic 5‐FU HAI using W spiral catheter™ and subsequent catheter extirpation is a promising strategy following curative resection of colorectal liver metastases. J. Surg. Oncol. 2004;88:248–255. © 2004 Wiley‐Liss, Inc.
Cover Picture: Macromol. Chem. Phys. 17/2004
Authors: Vennes Melanie , Zentel Rudolf
Published: November 2004

Cover: The picture shows optical and polarizing microscope images of textures (top) and colloidal particles (middle and bottom) of nematic and smectic liquid‐crystalline acrylate polymers. The schematic drawing shows two possible orientations of the mesogens within these colloids.

Further details can be found in the Full Paper by M. Vennes and R. Zentel* on page 2303.
Cover Picture: Macromol. Mater. Eng. 11/2004
Authors: Chiovetta Mario G. , Estenoz Diana A.
Published: November 2004

Cover: A cube‐cell mathematical model predicts the behavior of catalyst/product particles in a CSTR for ethylene polymerization under typical commercial conditions. Representation of the changing morphologies for some typical supports in high‐activity metallocenes is performed, with density and porosity evolutions calculated. For the parameters employed, to increase the catalyst activity not necessarily should produce a proportional increase in polymer yields.

Further details can be found in the Full Paper by M. G. Chiovetta* and D. A. Estenoz on page 1012.
Finite Element Analysis of Eigendynamics of Rolling Tires
Authors: Brinkmeier Maik , Nackenhorst Udo
Published: November 2004

The eigenvalue analysis of rolling tires is one part of the simulation of tire rolling noise radiation for the reduction of traffic noise. In this paper the general strategies of numerical eigenvalue analysis for nonsymmetric matrices are shown. The special effects observed on rotating bodies are discussed in details. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On loss of stability of slow motions in stiff oscillatory systems
Authors: Gusenkova Alla , Steindl Alois , Troger Hans
Published: November 2004

In stiff oscillatory systems often a reduction of the order of the system is possible by splitting the motion into an essential motion on a nearby slow manifold and neglecting the fast motion. However, if the system is conservative the question of stability of the slow motion is a delicate problem. For various spring pendulum systems we, first, perform numerical simulations showing that if the stiffness of the springs is gradually reduced the slow motion looses stability. For a single spring pendulum we give an explanation of this loss of stability. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Damping Of Pedestrian‐Induced Bridge Vibrations By Tuned Liquid Column Dampers
Authors: Reiterer Michael , Hochrainer Markus
Published: November 2004

The excessive lateral vibrations of Londons Millenium Bridge and the Toda Park Bridge in Japan due to a large number of crossing pedestrians have raised an unexpected problem in footbridge constructions. Secondary tuned structures, like the conventional tuned mass damper (TMD) or the tuned liquid damper (TLD) were installed to the bridge in order to suppress these vibrations. In the present investigation it is proposed to apply the more efficient and more economic tuned liquid column damper (TLCD), which relies on the motion of a liquid mass in a sealed tube to counteract the external motion, while a built‐in orifice plate induces turbulent damping forces that dissipate kinetic energy. For optimal tuning of TLCDs the natural frequency and equivalent linear damping coefficient have to be chosen suitable, likewise to the conventional TMDs, as given in Den Hartog [1]. The advantages of TLCDs are: simple tuning of natural frequency and damping, low cost of design and maintenance and a simple construction. A mathematical model of a three degree‐of‐freedom (DOF) bridge coupled with an optimal tuned TLCD is derived and analyzed numerically. Furthermore, a small scale experimental model set‐up has been constructed in the laboratory of the TU‐Insitute. The experimental results are in good agreement with the theoretical predictions and indicate that TLCDs are effective damping devices for the undesired pedestrian induced footbridge vibrations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Motion analysis of digitally controlled machines
Authors: Baksa István , Stéphán Gábor
Published: November 2004

The non‐linear dynamics of digital position control is investigated in the presence of Coulomb friction and round‐off errors. Periodic, transient chaotic, chaotic motions are found even in linear stable cases. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and Control of a Hydraulic Actuated Large Scale Manipulator
Authors: Stadlmayr Richard , Schlacher Kurt
Published: November 2004

This contribution deals with the modelling and control of an elastic manipulator. The arm is actuated by a hydraulic ram due to the significant weight. The overall goal is to achieve good tracking of the tip, as well as to reject disturbances, which act on the flexible arm. The controller design is based on two approaches. A flatness‐based feedforward control takes care of the tracking behaviour, and a passivity‐based feedback law stabilizes the trajectories and suppresses the elastic vibrations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Design of a nonlinear observer using automatic differentiation
Authors: Winkler Jan , Lindert Sven‐Olaf , Röbenack Klaus , Rudolph Joachim
Published: November 2004

Observer design for a class of observable nonlinear systems is considered. By a coordinate transformation and linearization around a desired trajectory the problem is reduced to the design for a linear time varying system. Calculation of the observer gain, depending on the desired trajectory, requires several derivatives. These are calculated using automatic differentiation by a combination of forward and reverse mode. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anwendung eines O(N) Algorithmus auf elastische Mehrkörperketten
Authors: Ferrara Paolo , Bremer Hartmut
Published: November 2004

Handhabungs und Fertigungsroboter sind, dam aktuellen Stand der Technik entsprechend, starr gebaut um den hohen Ansprüchen an Genauigkeit und Geschwindigkeit zu genügen. Neuartige Serviceroboter für Haushalts‐ oder Rehabilitationsaufgaben könnten hingegen in Leichtbauweise, elastisch konstruiert werden. Ein häufig angewandtes Regelungskonzept, das einer Vorsteuerung (Inversdynamik) plus Regelung der kleinen restlichen Abweichungen, erfordert ein vollständig beobachtetes System um Modellungenauigkeiten und Störungen bestmöglich zu kompensieren. Sowohl Zustands‐ als auch Störbeobachter werden dabei durch ein realitätsnahes Modell stark vereinfacht, wenn dieses Modell in Echtzeit gelöst und simuliert wird. Jede Abweichung der Realität vom idealen Modell wäre dann als Störgröße interpretierbar. Die Methodik für die Aufstellung solcher, schnell lösbarer, Bewegungsgleichungen (Ordnung N) wurde in [1] beschrieben und wird in dieser Arbeit als Implementierung in Matlab‐Simulink vorgestellt. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Micro‐Sphere Model for Rubber Viscoelasticity: A Micromechanically Based Network Model for Polymers.
Authors: Göktepe Serdar , Miehe Christian
Published: November 2004

The micromechanically based non‐affine elastic network model incorporating topological constraints has been recently proposed in Miehe et al. [3]. In the current contribution we advance the micro‐sphere elastic full network model so that it accounts for the rate dependent viscous effects. The viscoelastic network model is constructed by additively dividing the total network response into elastic and viscous parts. The equilibrium response of the material is described by the model proposed in Miehe et al. [3]. The time‐dependent overstress response is based on the two basic mechanisms: the retraction of the unconstrained dangling chains by diffusive reptile motion and the release of constraint effects due to the surrounding chains. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal Analysis of Free‐Corner Effects in Cross‐Ply Plates by a Higher‐Order Theory Approach
Authors: Longeru Markus , Mittelstedt Christian , Becker Wilfried
Published: November 2004

Stresses in the vicinity of free edges and corners of composite laminates exhibit a distinct localized three‐dimensional behaviour [1] and thus represent an important technical situation. Since numerical analyses of stress concentration phenomena in layered structures are computationally expensive, the present contribution is devoted to a simple closed‐form higher‐order theory approach for the calculation of displacements, strains and stresses in the vicinity of a rectangular corner of symmetric cross‐ply laminates under uniform thermal load ΔT. An appropriate representation for the displacement field in the form of a single‐layer theory with unknown inplane components and appropriately assumed functions through the plate thickness yields closed‐form expressions for the strains and stresses throughout the whole laminate. Equilibrium and boundary conditions are fulfilled in an integral sense. The present approach is easily applied, is of a completely closed‐form analytic nature and requires only little computational effort. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A SimpleModel for Anisotropic Damage with Applications to Soft Tissues
Authors: Balzani Daniel , Schröder Jörg , Gross Dietmar
Published: November 2004

Arteries are reinforced by helically arranged collagen fibers and posses orthotropic elastic properties. In this paper a polyconvex anisotropic energy is used in order to guarantee the existence of minimizers for the purely elastic boundary value problem. Anisotropic discontinuous damage effects, which are induced by decreasing stiffness of particular fibers, are observed in a certain range of overexpansion. A simple thermodynamical consistent anisotropic damage model is constructed, basing on the assumption that damage mainly takes place in the fiber directions as a result of breakage of collagen cross‐links.Finally a cycled overexpansion of a test material from an artery is analyzed in order to show the main characteristics of the proposed model. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Entwicklung eines 4‐Knoten‐Elements zur Berechnung von Nanostrukturen
Authors: Nasdala Lutz , Ernst Gerald , Rothert Heinrich
Published: November 2004

Zur Berechnung von Nanostrukturen wie z.B. Kohlenstoff‐Nanoröhren stehen eine Reihe von Kraftfeld‐Ansätzen (force fields) zur Verfügung, die sich aus molekulardynamischen Untersuchungen bzw. quantenmechanischen “ab initio” Berechnungen herleiten lassen. Sie liefern die potentielle Energie einer Struktur in Abhängigkeit von der Art und Anzahl der chemischen und physikalischen Bindungen. Die verschiedenen Energieformen lassen sich grundsätzlich mit nichtlinearen Normalkraft‐, Biegemomenten‐ und Torsionsmomentenfedern vergleichen, so dass der Einsatz von Finite Elemente Programmen nahe liegt. Aufgrund der Interaktion mehrerer Atome und der Tatsache, dass Atome keine Rotationsfreiheitsgrade im mechanischen Sinne besitzen, ist die Anwendung von Standard‐Elementen wie Stab‐, Balken‐ oder Schalenelementen problematisch. Beispielsweise führt die Verdrehung von Balkenelementen zu unerwünschten Zwängungen in angrenzenden Molekülgruppen. Aus diesem Grund wird eine neues 4‐Knoten‐Element entwickelt, das ausschließlich Verschiebungen als Freiheitsgrade benutzt und somit in der Lage ist, die verschiedenen Energieformen exakt abzubilden. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐Mechanical Modelling of the Constitutive Behaviour of NiTi Shape Memory Alloys
Authors: Zhang Wenge , Hackl Klaus , Hoppe Ulrich
Published: November 2004

The superelasticity and shape memory effect in NiTi alloys are examined on the basis of micromechanics within the energy minimization framework. We describe the behaviour of polycrystalline shape‐memory alloys via orientation‐distribution of the various martensite‐variants (domains) present in the material. Stress‐strain curves are presented and special attention is payed to the volume fraction of martensite for specific NiTi alloys (Nitinol) specimen under uniaxial tension. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved prenatal detection of a fetal point mutation for achondroplasia by the use of size‐fractionated circulatory DNA in maternal plasma—case report
Authors: Li Y. , Holzgreve W. , Page‐Christiaens G. C. M. L. , Gille J. J. P. , Hahn S.
Published: November 2004

Introduction

The efficacious analysis of fetal loci involving point mutations from circulatory fetal DNA in maternal plasma is hindered by the preponderance of maternal DNA. It has recently been shown that the size difference between fetal and maternal DNA species can be used for the selective enrichment of circulatory fetal DNA in maternal plasma. We have now tested this approach for the detection of a fetal point mutation in the fibroblast growth factor receptor 3 (FGFR3) gene that causes achondroplasia.

Methods

Circulatory DNA was extracted from maternal plasma and size‐fractionated by agarose gel electrophoresis. The fraction with a size less than 300 bp was examined by a touchdown PCR assay specific for the FGFR3 gene, and the mutation was identified by SfcI restriction analysis.

Result

Our analysis indicated that although the fetal mutation was discernible in the analysis of total plasma DNA, the result using size‐fractionated DNA was much more evident.

Conclusion

The enrichment of circulatory fetal DNA in maternal plasma by size‐fractionation facilitates the detection of subtle feto‐maternal genetic differences, such as those involving point mutations. This approach can easily be extended for the non‐invasive prenatal determination of other fetal loci. (190) Copyright © 2004 John Wiley & Sons, Ltd.
Cost‐effectiveness of prenatal screening for thalassaemia in Hong Kong
Authors: Leung K. Y. , Lee C. P. , Tang M. H. Y. , Lau E. T. , Ng L. K. L. , Lee Y. P. , Chan H. Y. , Ma E. S. K. , Chan Vivian
Published: November 2004

Objectives

To determine the cost effectiveness of a universal prenatal screening program for α‐ and β‐thalassaemia.

Methods

We retrospectively reviewed our program from 1998 to 2002, and calculated the direct and indirect costs of various components.

Results

18 936 women were screened at our prenatal clinic and 153 couples were subsequently referred to our Prenatal Diagnostic Centre for counselling and further investigations. In addition, there were 238 tertiary referrals and 157 self‐referrals. After investigations, 84 fetuses were at risk of β‐thalassaemia major/β‐E thalassaemia, 19 of them were affected and 18 were aborted. The total expenditure on our program (HK$10.0 million) would be less than the postnatal service costs (HK$40.4 million) for 18β‐thalassaemia major fetuses if they were born. Of 361 women at risk of carrying a homozygous α0‐thalassaemia fetus, 311 (86.2%) opted for the indirect approach (using serial ultrasound examinations to exclude Hb Bart's disease), and 76 (24.5%) subsequently underwent an invasive test for a definitive diagnosis. The sensitivity and false positive rate of this indirect approach was 100.0% and 2.9% respectively.

Conclusion

It is cost effective to run a universal prenatal screening program in an area where both β‐thalassaemia and α‐thalassaemia are prevalent. The indirect approach can effectively avoid an invasive test in unaffected pregnancies. Copyright © 2004 John Wiley & Sons, Ltd.
Prenatal diagnosis of deletion of chromosome 6p presenting with hydrops fetalis
Authors: Suwanrath‐Kengpol Chitkasaem , Limprasert Pornprot , Mitarnun Winyou
Published: November 2004

Objective

To report the first known case of 6p deletion presenting in utero with hydrops fetalis and multiple anomalies in the second trimester of pregnancy.

Methods

A thirty‐year‐old woman (gravida 3 para 1 abortion 1) was referred to our hospital at 18 weeks of gestation because of suspicion of fetal anomaly on routine ultrasound examination. A detailed anomaly scan revealed a single viable fetus with marked skin edema, marked ascites, pleural effusion, hydronephrosis of left kidney, absence of right kidney, cardiac anomaly and oligohydramnios. The fetal face was not visible due to the fetal position. Fetal karyotyping revealed 46,XX,del(6)(p21.3). The couple opted to terminate the pregnancy.

Results

A hydropic female fetus was aborted and the autopsy revealed hydrops fetalis with bilateral cleft lips, hydronephrosis of left kidney, absence of right kidney, spleen, and thymus gland, truncus arteriosus, and single umbilical artery. Cord blood and tissue culture confirmed that the fetus had deletion of chromosome 6p.

Conclusion

Deletion of short arm of chromosome 6 can result in hydrops fetalis in early pregnancy. Copyright © 2004 John Wiley & Sons, Ltd.
Termination of pregnancy: attitudes and behavior of women in a traditional society
Authors: Shoham‐Vardi I. , Weiner N. , Weitzman D. , Levcovich A.
Published: November 2004

Objectives

The Bedouin Arabs, a Muslim traditional ethnic minority in Israel, are faced with difficult choices when offered prenatal diagnosis as part of the universally provided prenatal care in Israel. This paper is to examine attitudes towards and practice of pregnancy termination, following an unfavorable prenatal diagnosis.

Methods

Semistructured interviews with 83 women were conducted to study attitudes. Data from the Soroka Medical Center, where all births in the area take place, were used to assess the rate of terminations of pregnancies following a diagnosis of a chromosomal anomaly.

Results

While divided on the question of termination, many women believed that a second medical opinion is needed, preferably from an Arab physician. The reasons for termination are both child‐ and mother‐related. Opposing termination is based on both the suspicion that the diagnosis might be wrong and on religious reasons. Between 1995 and 1999, 686 Bedouin women had undergone amniocentesis (2.4% of all pregnancies). Six of 11 pregnancies with the diagnosis of a trisomy were terminated (54.5%). All cases in which a trisomy was terminated were trisomy 21.

Conclusions

Culturally acceptable prenatal diagnostic services for Muslim populations should be based on early testing, and should involve Muslim physicians and religious authorities. Copyright © 2004 John Wiley & Sons, Ltd.
Morphology and mechanical properties of injection molded poly(ethylene terephthalate)
Authors: Viana Júlio C. , Alves Natália M. , Mano João F.
Published: November 2004

This work reports on the relationships between processing, the morphology and the mechanical properties of an injection molded poly(ethylene terephthalate), PET. Specimens were injection molded with different mold temperatures of 30°C, 50°C, 80°C, 100°C, 120°C, 150°C, while maintaining constant the other operative processing parameters. The thermomechanical environment imposed during processing was estimated by computer simulations of the mold‐filling phase, which allow the calculation of two thermomechanical indices indicative of morphological development (degree of crystallinity and level of molecular orientation). The morphology of the moldings was characterized by differential scanning calorimetry (DSC) and by hot recoverable strain tests. The mechanical behavior was assessed in tensile testing at 5 mm/min and 23°C. A strong thermal and mechanical coupling is evidenced in the injection molding process, significantly influencing morphology development. An increase in the mold temperature induces a decrease of the level of molecular orientation (decrement in the hot recoverable strain) and an increment in the initial crystallinity of the moldings (decrement in the enthalpy of cold crystallization), also reflected in the variations of the computed thermomechanical indices. The initial modulus is mainly dependent upon the level of molecular orientation. The yield stress is influenced by both the degree of crystallinity and the level of molecular orientation of the moldings, but more significantly by the former. The strain at break was not satisfactorily linked directly to the initial morphological state because of the expected morphology changes occurring during deformation. Polym. Eng. Sci. 44:2174–2184, 2004. © 2004 Society of Plastics Engineers.
Isothermal and nonisothermal crystallization kinetics of syndiotactic polystyrene/clay nanocomposites
Authors: Wu Tzong‐Ming , Hsu Sung‐Fu , Chien Cheng‐Fung , Wu Jeng‐Yue
Published: November 2004

Differential scanning calorimeter (DSC) and X‐ray diffraction methods were used to investigate the isothermal and nonisothermal crystallization behavior and crystalline structure of syndiotactic polystyrene (sPS)/clay nanocomposites. The sPS/clay nanocomposites were prepared by mixing the sPS polymer solution with the organically modified montmorillonite. DSC isothermal results revealed that introducing 5 wt% of clay into the sPS structure causes strongly heterogeneous nucleation, inducing a change of the crystal growth process from mixed three‐dimensional and two‐dimensional crystal growth to two‐dimensional spherulitic growth. The activation energy of sPS drastically decreases with the presence of 0.5 wt% clay and then increases with increasing clay content. The result indicates that the addition of clay into sPS induces the heterogeneous nucleation (a lower ΔE) at lower clay content and then reduces the transportation ability of polymer chains during crystallization processes at higher clay content (a higher ΔE). We studied the non‐isothermal melt‐crystallization kinetics and melting behavior of sPS/clay nanocomposites at various cooling rates. The correlation among crystallization kinetics, melting behavior and crystalline structure of sPS/clay nanocomposites is discussed. Polym. Eng. Sci. 44:2288–2297, 2004. © 2004 Society of Plastics Engineers.
Temperature control of injection molding. Part I: Modeling and identification
Authors: Diduch Chris , Dubay Rickey , Li Wan Gui
Published: November 2004

This paper develops a mathematical model for the dynamics of a plastic injection molding machine (IMM) that may be used for the design of a temperature‐control system. The research in this paper is novel in comparison to others since the derived models explicitly include the effects of zone interaction and backpressure, and do not lump these into an arbitrary disturbance signal. A series of experiments were conducted on a 150‐tonne IMM to identify the parameters of the proposed model using measurements of zone temperatures, percentage heater input, backpressure and screw speed. The identified model was validated using a series of blind tests that compared the model output with the measured barrel temperatures of the IMM. Polym. Eng. Sci. 44:2308–2317, 2004. © 2004 Society of Plastics Engineers.
The effect of molding conditions on mechanical and morphological properties at the interface of film insert injection molded polypropylene‐film/polypropylene matrix
Authors: Leong Y. W. , Yamaguchi S. , Mizoguchi M. , Hamada H. , Ishiaku U. S. , Tsujii T.
Published: November 2004

An extensive study on the peel strength between a polypropylene (PP) film and PP substrate fabricated using film insert injection molding technique was carried out through a 180° peel test. Injection molding conditions such as barrel temperature, injection speed and holding pressure were varied to gauge their effects on the mechanical and morphological properties. Morphological observations were made at the film‐substrate interfacial regions by means of transmission electron microscopy (TEM). The injection molded products, with the films still attached, were subjected to bending and impact tests to determine if there is any relationship between film‐substrate adhesion and bulk properties. Observation of the load‐displacement curves during the peel test revealed three unique and interesting curves, corresponding to different peeling and film fracture mechanisms. Increases in injection speed, barrel temperature and holding pressure lead to increased bonding between the film and substrate surfaces. The enhancement of bonding between these two polymer surfaces could be attributed to polymer‐polymer interdiffusion. Substantiating evidence from TEM, which shows the fading of the interface as the bond strengthens, further boosts the accuracy of this assumption. The hope that the films could contribute to enhancing bulk properties has been diminished since the bending properties appeared to be similar with or without the film attached. Polym. Eng. Sci. 44:2327–2334, 2004. © 2004 Society of Plastics Engineers.
Automatic mass spectrometry method development for drug discovery: application in metabolic stability assays
Authors: Chovan Linda E. , Black‐Schaefer Candace , Dandliker Peter J. , Lau Yau Yi
Published: November 2004

High‐throughput metabolic screening has been requested routinely to keep pace with high‐throughput organic synthesis. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) with a fast gradient has become the method of choice for the task due to its sensitivity and selectivity. We have developed an automated system that consists of a robotic system for in vitro incubation and a commercially available software package for automatic MS/MS method development. A short, generic LC gradient and MS conditions that are applicable to most compounds have been developed to minimize the method development time and data analysis. This system has been used to support a number of in vitro screening assays in early drug discovery phase including microsomal stability and protein binding. Copyright © 2004 John Wiley & Sons, Ltd.
Kommentare zur DIN EN14015
Authors: Bußhaus Ludger
Published: November 2004

Zur neuen europäischen Anwendungsnorm für Flachbodentanks DIN EN 14015 wird kein offizieller Kommentar vom CEN/TC 265 herausgegeben. Deshalb sollen die nachstehenden Kommentare den Anwender auf kritische Punkte hinweisen, die eigentlich alle in einem Nationalen Vorwort hätten aufgeführt werden sollen.
Bax‐induced cell death in Candida albicans
Authors: De Smet Kris , Eberhardt Ines , Reekmans Rieka , Contreras Roland
Published: November 2004

Bax is a pro‐apoptotic member of the Bcl‐2 family of proteins involved in the regulation of genetically programmed cell death in mammalian cells. It has been shown that heterologous expression of Bax in several yeast species, such as Saccharomyces cerevisiae, Schizosaccharomyces pombe and Pichia pastoris, also induces cell death. In this study we investigated the effects of Bax expression in the pathogenic yeast Candida albicans. Cell death inducing expression of Bax required a synthetic BAX gene that was codon‐optimized for expression in Candida albicans. Expression of this BAX gene resulted in growth inhibition and cell death. By fusing Bax with the yeast enhanced green fluorescent protein of Aequoria victoria, the cell death‐inducing effect of Bax was increased due to reduced proteolytic degradation of Bax. Using this fusion protein we showed that, upon expression in C. albicans, Bax co‐localizes with the mitochondria. Furthermore, we showed for the first time that expression of Bax in yeast causes the mitochondria, which are normally distributed throughout the cell, to cluster in the perinuclear region. Copyright © 2004 John Wiley & Sons, Ltd.
Alcohol‐mediated haemolysis in yeast
Authors: Shuster Amir , Osherov Nir , Rosenberg Mel
Published: November 2004

Although yeast are generally non‐haemolytic, we have found that addition of alcohol vapour confers haemolytic properties on many strains of yeast and other fungi. We have called this phenomenon ‘microbial alcohol‐conferred haemolysis’ (MACH). MACH is species‐ and strain‐specific: whereas all six Candida tropicalis strains tested were haemolytic in the presence of ethanol, none among 10 C. glabrata strains tested exhibited this phenomenon. Among 27 C. albicans strains and 11 Saccharomyces cerevisiae strains tested, ethanol‐mediated haemolysis was observed in 11 and 4 strains, respectively. Haemolysis is also dependent on the alcohol moiety: n‐butanol and n‐pentanol could also confer haemolysis, whereas methanol and 2‐propanol did not. Haemolysis was found to be dependent on initial oxidation of the alcohol. Reduced haemolysis was observed in specific alcohol dehydrogenase mutants of both Aspergillus nidulans and S. cerevisiae. MACH was not observed during anaerobic growth, and was reduced in the presence of pararosaniline, an aldehyde scavenger. Results suggest that initial oxidation of the alcohol to the corresponding aldehyde is an essential step in the observed phenomenon. Copyright © 2004 John Wiley & Sons, Ltd.
Expression and secretion of a prokaryotic protein streptokinase without glycosylation and degradation in Schizosaccharomyces pombe
Authors: Kumar Raj , Singh Jagmohan
Published: November 2004

Streptokinase (SK) is an important thrombolytic protein that is secreted by pathogenic strains of Streptococcus. Expression of streptokinase has been so far attempted in Pichia pastoris, Escherichia coli and Bacillus subtilis and shown to yield protein that was either highly glycosylated or degraded. Since the fission yeast, Schizosaccharomyces pombe, shares several molecular characteristics with higher eukaryotes, we decided to express the streptokinase gene in this yeast. A chimeric gene comprising the signal sequence of the Plus pheromone of Sz. pombe fused in‐frame with the mature streptokinase from Streptococcus sp. was constructed and inserted into the expression vector containing the thiamine‐regulated promoter. We obtained a high level of expression of streptokinase comparable to that in E. coli and P. pastoris, with 50–100% processing of the signal sequence and secretion of the mature streptokinase into the periplasmic fraction. The mature enzyme co‐migrates with the authentic mature SK in SDS gels, lacks any major modification and is functional. Importantly, a higher level of expression under stationary phase conditions and improved extractability of the mature and undegraded streptokinase was achieved in a novel mutant of Sz. pombe defective for a potent extracellular protease activity. We suggest that the unique vector/strain system developed here could be advantageous for large‐scale production of prokaryotic proteins without significant modification or degradation in Sz. pombe. Copyright © 2004 John Wiley & Sons, Ltd.
YAP4 gene expression is induced in response to several forms of stress in Saccharomyces cerevisiae
Authors: Nevitt Tracy , Pereira Jorge , Rodrigues‐Pousada Claudina
Published: November 2004

Exposure of Saccharomyces cerevisiae to several environmental insults, including conditions of oxidative, heavy metal, metalloid and heat stress, induces the expression of the YAP4 gene, previously shown to play a role in the response to hyperosmotic stress. Expression analyses in several mutant strains under pro‐oxidant conditions have determined that YAP4 is regulated by the transactivators Yap1p and Msn2p. Mutation of either the Yap1p‐response element (YRE), located at − 517 bp from the ATG, or the most proximal stress response element (STRE) at −430 bp, is shown to strongly compromise YAP4 gene expression under these conditions. Furthermore, these two mutations in combination lead to a severe depletion of detectable mRNA levels, indicating interplay between the transcription factors Yap1p and Msn2p in the regulation of YAP4 transcription. Transcriptional activation of this gene reflects a concomitant increase in Yap4p protein levels that appear phosphorylated upon stress and negatively regulated by protein kinase A. Yap4p amino acid residues Ser89, Ser196 and Thr241 are shown to be required for protein phosphorylation and/or protein stability. Copyright © 2004 John Wiley & Sons, Ltd.
The risks and benefits of participating in trauma‐focused research studies
Authors: Newman Elana , Kaloupek Danny G.
Published: November 2004

Concern about minimizing harm and maximizing benefit has been particularly acute with regard to the scientific study of individuals exposed to potentially traumatic events such as terrorist attack or disaster. This review outlines conceptual and practical issues and summarizes available evidence regarding potential risks and benefits of participation in trauma‐related research. Current, limited evidence suggests that most individuals make favorable cost–benefit appraisals regarding their participation. Although a subset of participants report strong negative emotions or unanticipated distress, the majority of these do not regret or negatively evaluate the overall experience. Continuing efforts are needed to identify individuals at risk for unfavorable reactions to research participation. A systematic empirical approach to evaluating participant experience in all human research is recommended.