bluuebunny/crossref_metadata_2025 huggingface dataset:
Low barrier kinetics: Dependence on observables and free energy surface
Authors: Ma Hairong , Gruebele Martin
Published: November 2005

Dynamics on free energy surfaces with high activation barriers are usually treated by few‐state kinetics models, yielding characteristic rate coefficients and amplitudes depending on the connectivity of the states. When the barriers are low (<3kT), the assumption of instantaneous equilibration of the transition state, and hence, the few‐state kinetics treatment, break down. Langevin dynamics is used here to explore the characteristic trends that occur in such cases, as a function of barrier height, number of barriers, dimensionality of the free energy surface, and switching functions that describe how spectroscopic probes vary from reactant to product. The result is a systematic phenomenological description of low barrier kinetics and dynamics. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 125–134, 2006
Numerical instabilities in the computation of pseudopotential matrix elements
Authors: Wüllen Christoph van
Published: November 2005

Steep high angular momentum Gaussian basis functions in the vicinity of a nucleus whose inner electrons are replaced by an effective core potential may lead to numerical instabilities when calculating matrix elements of the core potential. Numerical roundoff errors may be amplified to an extent that spoils any result obtained in such a calculation. Effective core potential matrix elements for a model problem are computed with high numerical accuracy using the standard algorithm used in quantum chemical codes and compared to results of the MOLPRO program. Thus, it is demonstrated how the relative and absolute errors depend an basis function angular momenta, basis function exponents and the distance between the off‐center basis function and the center carrying the effective core potential. Then, the problem is analyzed and closed expressions are derived for the expected numerical error in the limit of large basis function exponents. It is briefly discussed how other algorithms would behave in the critical case, and they are found to have problems as well. The numerical stability could be increased a little bit if the type 1 matrix elements were computed without making use of a partial wave expansion. © 2005 Wiley Periodicals, Inc., J Comput Chem 27: 135–141 2006
Utilisation of C2–C4 gaseous hydrocarbons and isoprene by microorganisms
Authors: Shennan Jean L
Published: November 2005

Microorganisms able to grow on low molecular weight aliphatic hydrocarbon gases, i.e. the n‐alkanes, ethane, propane and butane, and the terminal alkenes, ethylene, propylene and butylene, are not uncommon but mainly belong to certain taxonomic groups. These microbes are described in this review together with the pathways by which the hydrocarbons are assimilated. Microbial oxidation of the volatile alkadiene, isoprene, is also discussed. Avenues for possible commercial exploitation of these metabolic activities are also reviewed. Short‐chain n‐alkane‐utilising organisms have been investigated as tools in petroleum exploration and for production of single cell protein. More recently microbes grown on gaseous hydrocarbons other than methane have been evaluated for use in biotechnological production of epoxides, synthesis of chiral epoxyalkanes and as catalysts in bioremediation systems. Copyright © 2005 Society of Chemical Industry
Removal of TEX vapours from air in a peat biofilter: influence of inlet concentration and inlet load
Authors: Gabaldón Carmen , Martínez‐Soria Vicente , Martín Miguel , Marzal Paula , Penya‐roja Josep‐Manuel , Alvarez‐Hornos F. Javier
Published: November 2005

This paper presents the results of the study of the removal of toluene, ethylbenzene, and o‐xylene (TEX) by biofiltration using a commercial peat as filter‐bed material. Runs with a single organic compound in air, and with the mixture of TEX in air, were carried out for at least 55 days in laboratory‐scale reactors inoculated with a conditioned culture. The influence of organic compound inlet load and of gas flow rate on the biofilter's performance was studied, including relatively high values of pollutant inlet concentration (up to 4.3 gC m−3 for ethylbenzene, 3.2 gC m−3 for toluene, and 2.7 gC m−3 for o‐xylene). Results obtained show maximum elimination capacities of 65 gC m−3 h−1 for o‐xylene, 90 gC m−3 h−1 for toluene, and 100 gC m−3 h−1 for ethylbenzene, and high removal efficiency (>90%) even for moderately elevated concentrations: 3.0, 2.5 and 1.8 gC m−3 for ethylbenzene, toluene and o‐xylene, respectively. The behaviour of the TEX mixture was in good agreement with the results obtained for the runs in which only one organic compound was present. Ethylbenzene and toluene are degraded easier than o‐xylene, and inhibitory effects due to the presence of multiple substrates were not observed. Copyright © 2005 Society of Chemical Industry
Optimisation study of large‐scale enzymatic synthesis of oleyl oleate, a liquid wax ester, by response surface methodology
Authors: Mat Radzi Salina , Basri Mahiran , Salleh Abu Bakar , Ariff Arbakariya , Mohammad Rosfarizan , Abdul Rahman Mohammad Basyaruddin , Raja Abdul Rahman Raja Noor Zaliha
Published: November 2005

An optimisation study of the large‐scale enzymatic synthesis of a liquid wax ester from oleic acid and oleyl alcohol using Novozym 435 was carried out. Investigations were performed in batch mode with a stirred tank reactor (STR) with one multi‐bladed impeller. Response surface methodology (RSM) based on a five‐level, three‐variable central composite rotatable design (CCRD) was used to evaluate the interactive effects of various parameters. The parameters are amount of enzyme (A) (90–120 g), impeller speed (B) (100–400 rpm) and temperature (C) (40–60 °C). The optimum conditions derived via RSM at a fixed reaction time of 1 h were successfully optimised as A = 104 g, B = 388.0 rpm and C = 49.7 °C. The actual experimental yield was 96.7% under the optimum conditions, which compared well with the maximum predicted value of 97.6%. Copyright © 2005 Society of Chemical Industry
PDT‐induced death of sensory neurons and glial cells in the isolated crayfish stretch receptor after proteolytic treatment
Authors: Lobanov A.V. , Uzdensky A.B.
Published: November 2005

To study the involvement of neuroglial interactions in photodynamic damage of crayfish stretch receptor, which consists of only two neurons surrounded by satellite glial cells (SGCs), we attempted to proteolytically uncouple neurons and glia and then compare the responses of these cells to photosensitization when intercellular communications were intact or impaired. After incubation of isolated stretch receptors with pronase or collagenase they were photosensitized with Photosens, a mixture of sulfonated alumophthalocyanines AlPcSn (n = 2, 3, and 4; mean n = 3.1). In the next 6 hr the preparations were double fluorochromed with propidium iodide and Hoechst‐33342 to visualize necrotic and apoptotic cells. Proteolytic treatment shortened bioelectric neuron response and precipitated its functional inactivation; however, it did not significantly impair neuron morphology and did not induce its necrosis either in the darkness or under photosensitization. Photodynamic treatment induced necrosis of neurons and SGC and apoptosis of glial cells. Pronase but not collagenase increased percent of necrotic and apoptotic SGCs in the darkness and thus reduced the number of glial cells around the neuron; however, both pronase and collagenase prevented photodynamically induced apoptosis of glial cells. The involvement of neuron‐to‐glia signaling interactions in this phenomenon is suggested. © 2005 Wiley‐Liss, Inc.
Nerve growth factor increases connexin43 phosphorylation and gap junctional intercellular communication
Authors: Cushing Paul , Bhalla Ruchi , Johnson Andrew M. , Rushlow Walter J. , Meakin Susan O. , Belliveau Daniel J.
Published: November 2005

The function of gap junctions is regulated by the phosphorylation state of their connexin subunits. Numerous growth factors are known to regulate connexin phosphorylation; however, the effect of nerve growth factor on gap junction function is not understood. The phosphorylation of connexin subunits is a key event during many aspects of the lifecycle of a connexin, including open/close states, assembly/trafficking, and degradation, and thus affects the functionality of the channel. PC12 cells infected with connexin43 (Cx43) retrovirus were used as a neuronal model to characterize the signal transduction pathways activated by nerve growth factor (NGF) that potentially affect the functional state of Cx43. Immunoblot analysis demonstrated that Cx43 and the mitogen‐activated protein kinase (MAPK), ERK‐1/2, were phosphorylated in response to TrkA activation via NGF and that phosphorylation could be prevented by treatment with the MEK‐1/2 inhibitor U0126. The effects of NGF on gap junction intercellular communication were examined by monitoring fluorescence recovery after photobleaching PC12‐Cx43 cells preloaded with calcein. Fluorescence recovery in the photobleached area increased after NGF treatment and decreased when pretreated with the MEK‐1/2 inhibitor U0126. These data are the first to show a direct signaling link between neurotrophins and the phosphorylation of connexin proteins through the MAPK pathway resulting in increased gap junctional intercellular communication. Neurotrophic regulation of connexin activity provides a novel mechanism of regulating intercellular communication between neurons during nervous system development and repair. © 2005 Wiley‐Liss, Inc.
Apotransferrin and the cytoskeleton of oligodendroglial cells
Authors: Ortiz Esteban H. , Pasquini Laura A. , Soto Eduardo F. , Pasquini Juana M.
Published: November 2005

Apotransferrin (aTf), has been shown to accelerate the differentiation of oligodendroglial cells (OLGcs) in primary cultures and to increase the expression of different components of the myelin cytoskeleton (CSK). We examined the incorporation and distribution of human aTf (aTfh) exogenously added to OLGcs cultures and its effects on the CSK of the OLGcs. When OLGcs treated with aTfh were extracted with a CSK‐stabilizing buffer containing detergent, aTfh was found in the soluble fraction. In vitro experiments showed that purified tubulin was not altered by the addition of aTfh. In OLGc primary cultures treated with aTfh, this glycoprotein showed a punctate distribution pattern along the OLGc processes. Treatment of the cultures with colchicine, cytochalasin, or taxol induced a displacement of the immunoreactivity of aTfh toward the OLGc soma. Analysis of the effects of aTfh on the cell distribution of tyrosinated and detyrosinated tubulin and STOP (stable tubule only polypeptide), showed that aTfh added to OLGc cultures promoted changes suggesting a stabilizing effect on the microtubules (MT) at the tip of the processes. Kinesin and dynein were found to colocalize with the aTfh, indicating that these motors participate in the transport of the added glycoprotein. Moreover, after treatment with aTfh, clathrin immunoreactivity was displaced from the OLGc body toward the cell processes. These results indicate that although aTfh added to OLGcs does not interact directly with CSK components, it seems to be transported in clathrin coated vesicles from the cell body to the tips of the OLGc processes where it promotes their stabilization. This mechanism may be of importance in the increased formation of the myelin membrane induced by aTf. © 2005 Wiley‐Liss, Inc.
Nitric oxide enhances collagen synthesis in cultured human tendon cells
Authors: Xia Wei , Szomor Zoltan , Wang Yao , Murrell George A.C.
Published: November 2005

Collagen deposition is an important process that occurs during wound healing. We and others have shown that nitric oxide (NO) is important in tendon healing. The mechanisms whereby healing is enhanced are, however, undetermined. The aim of this study was to investigate whether NO could enhance collagen synthesis in cultured human tendon cells via exogenous NO and via an adenovirus containing the gene for inducible nitric oxide synthase (Ad‐iNOS).

Tendon cells from the torn edge of the tendons of patients undergoing rotator cuff repair surgery were cultured following collagenase digestion, and stimulated with exogenous NO (SNAP), transfected with Ad‐iNOS, and treated with the NOS inhibitor, L‐NMMA. Total protein and collagen synthesis were evaluated by 3H‐proline and collagenase sensitive 3H‐proline incorporation in human tendon cells. High doses of exogenous NO (SNAP) inhibited collagen synthesis. Lower doses enhanced total protein and collagen synthesis of the tendon cells. Ad‐iNOS successfully transfected active iNOS into human tendon cells in vitro and also enhanced total protein and collagen synthesis of the tendon cells. The NOS inhibitor, L‐NMMA, inhibited the effects of iNOS on the cells.

Our studies show for first time that nitric oxide can enhance collagen synthesis in human tendon cells in vitro. These results may explain, in part, at least, the beneficial effects of NO donors in animal models and during the treatment of tendonopathies in human clinical trials. © 2005 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res
A critical view of the desertification debate in southeastern Spain
Authors: Martínez‐Fernández J. , Esteve M. A.
Published: November 2005

In Spain, desertification has been—and is still—mainly associated with soil erosion, particularly in natural and semi‐natural systems. Such association cannot be supported either from the scientific or the socio‐economic point of view. Most average values of erosion rates in Spain have been overestimated, especially in the case of natural systems. High rates of soil erosion in natural systems are usually restricted to spatially limited areas like badlands, most of them generated through active natural geomorphologic processes. The main erosion problems are not found in natural environments but in agricultural systems, especially in marginal agricultural areas on steep slopes and with bad agricultural practices and also in intensively irrigated lands, especially greenhouses. The association of arid zones with the ancient destruction of vegetation is rooted in simplistic ideas considering areas with scarce vegetation, little biomass or limited height to be generated by negative human interventions. However, in arid and semiarid systems this is not always true. The simplistic ideas linking scarce vegetation with desertification is also deeply negative for the conservation of the outstanding biodiversity of arid systems, most of them included in the European Habitat Directive. The main desertification problem in Spain is generated by unsustainable water management. The current expansion of irrigated lands outside the areas suited for agriculture is increasing the intensity of aquifer exploitation, already causing serious problems of salinization, the loss of springs and wetlands and associated biodiversity and the exhaustion of non‐renewable groundwater resources. Copyright © 2005 John Wiley & Sons, Ltd.
Soil quality evaluation and monitoring based on land evaluation
Authors: Rosa D. de la
Published: November 2005

Soil quality evaluation is the process of predicting the capacity of a soil to function. Due to the many possible soil functions, simple measuring of an individual soil parameter is not sufficient. These soil‐quality parameters or indicators are grouped in physical, chemical and biological components. Land evaluation, which tries to predict land behaviour for each particular use, is not the same as soil‐quality assessment, basically because the biological parameters of the soil are not considered by land evaluation. However, the process of evaluating soil is not new, and agro‐ecological land evaluation has much to offer in this sense. A state‐of‐the‐art review of soil quality evaluation and monitoring is presented in this paper, focusing on the possibilities of applying the accumulated knowledge from past studies of land evaluation. An agro‐ecological approach is suggested to facilitate the monumental task of relating the nearly infinite list of soil quality indicators to the numerous soil functions, such as an application of MicroLEIS DSS to soil quality. Copyright © 2005 John Wiley & Sons, Ltd.
Rheology Study of Wafer Level Underfill
Authors: Sun Yangyang , Zhang Zhuqing , Wong Ching Ping
Published: November 2005

Summary: As a special epoxy resin material used in the electronics packaging, wafer level underfill (WLU) is studied using a chemorheology approach to provide a fundamental understanding of its reaction dependent rheology behaviors. In this work, the relationship between the molecular weight ($\overline M _{\rm w}$) and the viscosity of the epoxy resins at fixed temperatures has been established. Subsequently an Arrhenius‐Erying equation was used to fit the relationship between viscosity and temperature for given molecular weight epoxies. By combining the two relationships, the viscosity could be modeled as a function of temperature and molecular weight. To obtain the viscosity change of the WLU during the reflow process, the molecular weight change of the underfill was calculated from the degree of curing through the kinetics modeling. A semi‐empirical model was developed to predict the viscosity of the underfill as a function of time and temperature during the curing process. Modeled predictions were compared with experimental data under isothermal and ramping temperatures during curing experiments. The model showed good agreement with the experiments in the early stage of curing reaction. The critical viscosity of the underfill for solder wetting was obtained by wetting experiments, which can be used as the criteria to determine the flowability of the wafer level underfill.

Data fitting of the viscosity model at isothermal condition.

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Data fitting of the viscosity model at isothermal condition.
Layered Silicate‐Induced Enhancement of Fracture Toughness of Epoxy Molding Compounds over a Wide Temperature Range
Authors: Tark Han Joong , Cho Kilwon
Published: November 2005

Summary: The fracture toughness of EMC was dramatically increased over a wide temperature range by the addition of a very low volume fraction of layered silicates to EMC filled with micro‐silica particles. Layered silicate‐EMC nanocomposites containing intercalated and the exfoliated silicates were fabricated by using o‐cresol and biphenyl type epoxy resins, respectively. It was found that exfoliated silicates were more effective than intercalated silicates at toughening EMC at temperatures above Tg of the epoxy resin. Enhanced fracture toughness of EMC over a wide temperature range, from ambient to 230 °C has been attributed to the presence of layered silicates, which induces macroscopic crack deflection and severe plastic deformation in front of the crack tip.

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Superoxide anion radical generation in the NaOH/H2O2/Fe(III) system: a spin trapping ESR study
Authors: Zhou Nie , Qiu Tian , Yang‐ping Liu , Yang Liu
Published: November 2005

Formation of free radical intermediates in a NaOH/H2O2/Fe(III) system has been studied by ESR spectroscopy in the presence of the spin trap 5,5‐dimethy‐1‐pyrroline N‐oxide (DMPO). DMPO/O− and DMPO/•OH signals were simultaneously detected in this system, but only the DMPO/•OH signal could be observed in the absence of Fe(III). Effects of pH values and Fe(III) concentrations on the ESR signal intensities were investigated in detail. Formation of DMPO/O− adduct was inhibited by the addition of superoxide dismutase (SOD), catalase or nitro blue tetrazolium (NBT), and by chelating the Fe(III) with some chelators, including ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and desferrioxamine (DFO). Deoxygenation from the NaOH/H2O2/Fe(III) mixture had a slight effect on the formation of DMPO/O−. DMPO/O− signal was also detected from the NaOH/H2O2/Fe(II) mixture, but it can be totally suppressed under anaerobic conditions. Considering the hydrolysis of Fe(III) into polymerization iron species with oxide phases in the alkaline medium, Fe2O3 was directly suspended into a mixture of NaOH/H2O2 for comparison. Fortunately, the presence of Fe2O3 suspension was found to be of benefit to the production of DMPO/O−. Influence of aging time of hydrolytic iron species on the superoxide anion radical generation was also studied. These results suggest that the generation of O− from the NaOH/H2O2/Fe(III) system was probably caused by the heterogeneous surface catalysis initiated by hydrolytic iron species. Copyright © 2005 John Wiley & Sons, Ltd.
Sensitivities of flow and transport parameters in fractured porous media using automatic differentiation
Authors: Vogel T. , Bachmann D. , Hauschild A. , Bücker H. M. , Köngeter J.
Published: November 2005

The hydraulic complexity of hardrock aquifers with, for example, fast fluid flow in fractures, storage effects in the rock matrix, high contrasts in permeability, and a high spatial variability of structures requires a high standard of experimental and numerical techniques. This paper focuses on the interpretation of tracer tests. The sensitivity of tracer breakthrough curves with respect to flow and transport parameters is analysed for different model types in order to identify the relevant flow and transport processes. This leads to a better understanding of the system behaviour and facilitates the interpretation of experimental results. The technique of automatic differentiation is used to evaluate the sensitivities. The main advantage of this technique is that the sensitivities are calculated without truncation error. Copyright © 2005 John Wiley & Sons, Ltd.
Robust adaptive remeshing strategy for large deformation, transient impact simulations
Authors: Erhart Tobias , Wall Wolfgang A. , Ramm Ekkehard
Published: November 2005

In this paper, an adaptive approach, with remeshing as essential ingredient, towards robust and efficient simulation techniques for fast transient, highly non‐linear processes including contact is discussed. The necessity for remeshing stems from two sources: the capability to deal with large deformations that might even require topological changes of the mesh and the desire for an error driven distribution of computational resources. The overall computational approach is sketched, the adaptive remeshing strategy is presented and the crucial aspect, the choice of suitable error indicator(s), is discussed in more detail. Several numerical examples demonstrate the performance of the approach. Copyright © 2005 John Wiley & Sons, Ltd.
A methodology for the formulation of error estimators for time integration in linear solid and structural dynamics
Authors: Romero I. , Lacoma Luis M.
Published: November 2005

In this article, we present a novel methodology for the formulation of a posteriori error estimators applicable to time‐stepping algorithms of the type commonly employed in solid and structural mechanics. The estimators constructed with the presented methodology are accurate and can be implemented very efficiently. More importantly, they provide reliable error estimations even in non‐smooth problems where many standard estimators fail to capture the order of magnitude of the error. The proposed methodology is applied, as an illustrative example, to construct an error estimator for the Newmark method. Numerical examples of its performance and comparison with existing error estimators are presented. These examples verify the good accuracy and robustness predicted by the analysis. Copyright © 2005 John Wiley & Sons, Ltd.
Efficient iteration schemes for anisotropic hyperelasto‐plasticity
Authors: Ekh M. , Menzel A.
Published: November 2005

Numerical issues arising when integrating hyperelasto‐plastic constitutive equations with elastic anisotropy, stemming from anisotropic damage, and plastic anisotropy as represented by kinematic hardening are discussed. In particular, solution algorithms for the corresponding non‐linear system of equations due to implicit integration algorithms are addressed. It is shown that algorithms like staggered iteration and quasi‐Newton techniques are superior to a pure Newton technique when the cpu time is compared. However, the drawback of the staggered and the quasi‐Newton technique is that rather small time steps must be taken to ensure convergence, which can be of importance when applying complex constitutive models in a finite element programme. Copyright © 2005 John Wiley & Sons, Ltd.
Skeletal reduction of boundary value problems
Authors: Suresh Krishnan
Published: November 2005

Boundary value problems posed over thin solids are amenable to a dimensional reduction in that one or more spatial variables may be eliminated from the governing equation, resulting in significant computational gains with minimal loss in accuracy. Extant dimensional reduction techniques rely on representing the solid as a hypothetical mid‐surface plus a possibly varying thickness. Such techniques are however hard to automate since the mid‐surface is often ill‐defined and ambiguous.

We propose here a skeletal representation based dimensional reduction of boundary value problems. The proposed technique has the computational advantages of mid‐surface reduction, but can be easily automated. A systematic methodology is presented for reducing boundary value problems to lower‐dimensional problems over the skeleton of a solid. The theoretical properties of the proposed method are derived, and supported by representative numerical experiments. Copyright © 2005 John Wiley & Sons, Ltd.
On the synthesis of time‐varying LQG weights and noises along optimal control and state trajectories
Authors: Van Willigenburg L. G. , De Koning W. L.
Published: November 2005

A general approach to control non‐linear uncertain systems is to apply a pre‐computed nominal optimal control, and use a pre‐computed LQG compensator to generate control corrections from the on‐line measured data. If the non‐linear model, on which the optimal control and LQG compensator design is based, is of sufficient quality, and when the LQG compensator is designed appropriately, the closed‐loop control system is approximately optimal. This paper contributes to the selection and computation of the time‐varying LQG weighting and noise matrices, which determine the LQG compensator design. It is argued that the noise matrices may be taken time‐invariant and diagonal. Three very important considerations concerning the selection of the time‐varying LQG weighting matrices are turned into a concrete computational scheme. Thereby, the selection of the time‐varying LQG weighting matrices is reduced to selecting three scalar design parameters, each one weighting one consideration. Although the three considerations seem straightforward they may oppose one another. Furthermore, they usually result in time‐varying weighting matrices that are indefinite, rather than positive (semi) definite as required for the LQG design. The computational scheme presented in this paper addresses and resolves both problems. By two numerical examples the benefits of our optimal closed‐loop control system design are demonstrated and evaluated using Monte Carlo simulation. Copyright © 2005 John Wiley & Sons, Ltd.
Automatic Geometry Based FE Model Generation for Optimization and Robust Design for Passive Safety of Passenger Vehicles
Authors: Hilmann Joergen , Paas Michel , Schindler Volker
Published: November 2005

In this paper the optimization of large scale vehicle structures is addressed. A process strategy based on Latin Hypercube sampling, genetic algorithm optimization, and sensitivity analysis is discussed. This process was implemented on a dedicated Linux Cluster, utilizing various free and commercially available software tools, including SFE Concept, Perl, Matlab, and Radioss. The viability of the method is demonstrated for a large scale vehicle model in an offset deformable barrier crash test at 64 kph impact velocity. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Projected Gradient Flows for BV/Level Set Relaxation
Authors: Burger Martin , Hintermüller Michael
Published: November 2005

This paper introduces a new level set method based on projected gradient flows for problems that can be solved by a recently introduced relaxation approach. For the class of problems the relaxation is exact, it can be shown that the solution of the flow converges to a solution of the relaxed problem for large time, and the level sets of the limit are solutions of the original problem. We introduce a simple computational scheme based on explicit time discretization and apply the method to imaging examples. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel Solution Methods for Porous Media Models in Biomechanics
Authors: Wieners C. , Ehlers W. , Ammann M. , Karajan N. , Markert B.
Published: November 2005

We present a biomechanical application of our parallel finite element model for coupled problems in solid mechanics. This programming framework provides a very lean and flexible interface, which allows to realize time‐dependent nonlinear simulations. In this context, a special variant of a stabilized local Gauß‐Seidel preconditioner is introduced, which can be successfully employed to large scale computations. Finally, the efficiency of the implemented algorithm is shown by a numerical example considering the axial compression of a L4‐L5 motion segment of the spine. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gradient evaluation in DAE optimal control problems by sensitivity equations and adjoint equations
Authors: Gerdts Matthias
Published: November 2005

The problem of calculating gradients for discretized optimal control problems is addressed. These gradients are needed by a sequential quadratic programming (SQP) method, which is used to solve the discretized optimal control problem. Two approaches for gradient calculation are discussed and compared numerically. The first approach uses sensitivity equations, the second uses adjoint equations. It turns out that it depends on the problem dimensions which approach is more preferable compared to the other. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards Matrix‐Free AD‐Based Preconditioning of KKT Systems in PDE‐Constrained Optimization
Authors: Griesse Roland , Walther Andrea
Published: November 2005

The presented approach aims at solving an equality constrained, finite‐dimensional optimization problem, where the constraints arise from the discretization of some partial differential equation (PDE) on a given space grid. For this purpose, a stationary point of the Lagrangian is computed using Newton's method, which requires the repeated solution of KKT systems. The proposed algorithm focuses on two topics: Firstly, Algorithmic Differentiation (AD) will be used to evaluate the necessary computations of gradients, Jacobian‐vector products, and Hessian‐vector products, so that only the objective f (y , u ) and the PDE constraint e (y , u ) = 0 have to be specified by the user. Secondly, we solve the KKT system iteratively using the QMR algorithm, with preconditioning provided by a multigrid approach. We wish to explore whether the Jacobian‐vector products provided by AD are sufficient to construct suitable multigrid preconditioners. Our approach is then embedded into a globalized optimization routine. Numerical results for optimization problems involving a nonlinear reaction‐diffusion model will be given. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rearrangement of chromosomal region 8q11–13 in lipomatous tumours: correlation with lipoblastoma morphology
Authors: Brandal Petter , Bjerkehagen Bodil , Heim Sverre
Published: November 2005

Cytogenetics is of considerable value when diagnosing lipomatous tumours, as different tumour types have different more or less specific chromosomal abnormalities. One such entity is lipoblastoma, which is a benign lipomatous tumour that often exhibits rearrangements of chromosome bands 8q11–13, and the gene PLAG1 has been implicated as the target of these chromosomal changes. All lipomatous tumours karyotyped at the Norwegian Radium Hospital were reviewed, looking for rearrangements of 8q11–13. Five tumours exhibiting chromosomal abnormalities affecting this region were found. Only one of them was morphologically diagnosed as a lipoblastoma, two being classified as lipomas, one as a hibernoma, and one as a well‐differentiated liposarcoma. The two tumours successfully analysed with bacterial artificial chromosomes (BACs) covering the gene PLAG1 showed involvement of this gene in the rearrangement. The findings raise the question as to what extent the diagnosis lipoblastoma should be based on histopathological or cytogenetic/molecular data or a combination thereof. When karyotypic information from this series was combined with available literature data, it was found that the sensitivity of 8q11–13 rearrangements for diagnosing lipoblastomas when found in a lipomatous tumour was 77% and that the corresponding specificity was 98%. The validity of these calculations of the diagnostic information provided by the cytogenetic findings is, of course, totally dependent on the morphological diagnosis made in each case. Regardless of what the precise phenotypic diagnosis was, it is suggested that lipomatous tumours with 8q11–13 rearrangement constitute a distinct pathogenetic entity. When selective therapies tailor‐made against the specific pathogenetic rearrangement become available, it will become mandatory to pay more attention to the genetic constitution of the tumour cells than to their phenotypic appearance. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Fatal pneumonitis in children with metastatic rhabdomyosarcoma following whole lung radiotherapy and sequential epirubicin
Authors: Prestwich R.J. , Picton S.V. , Glaser A. , Taylor R.E.
Published: November 2005

Interstitial pneumonitis is a recognized complication following whole lung radiotherapy. We report two cases in which fatal pneumonitis appeared to be precipitated by the administration of epirubicin‐containing combination chemotherapy within 7 weeks of completion of whole lung radiotherapy. These cases highlight a potentially fatal interaction between radiotherapy and modern chemotherapy regimens. Pediatr Blood Cancer 2007;48:586–590. © 2005 Wiley‐Liss, Inc.
Sinus histiocytosis with massive lymphadenopathy (Rosai–Dorfman disease) treated with 2‐chlorodeoxyadenosine
Authors: Tasso M. , Esquembre C. , Blanco E. , Moscardó C. , Niveiro M. , Payá A.
Published: November 2005

Sinus histiocytosis with massive lymphadenopathy (SHML) or Rosai–Dorfman disease (RDD) is a rare but well‐defined histiocytic proliferative disorder of unknown etiology that usually presents with cervical lymphadenopathy, fever, leukocytosis, and hypergammaglobulinemia in an otherwise healthy child. Although many patients undergo spontaneous remission, a subset of patients with systemic disease has a more serious course. For those patients with a poor outcome, steroids and chemotherapeutic agents such as etoposide or 6‐mercaptopurine plus low dose methotrexate have been used. We present a child with a massive cervical lymphadenopathy treated with 2‐chlorodeoxyadenosine (2‐CdA, cladribine) after other approaches failed. Pediatr Blood Cancer 2006; 47:612–615. © 2005 Wiley‐Liss, Inc.
Continuous or repeated prolonged cisplatin infusions in children: A prospective study on ototoxicity, platinum concentrations, and standard serum parameters
Authors: Lanvers‐Kaminsky C. , Krefeld B. , Dinnesen A.G. , Deuster D. , Seifert E. , Würthwein G. , Jaehde U. , Pieck A.C. , Boos J.
Published: November 2005

Background

To overcome the ototoxicity of cisplatin, single bolus infusions were replaced by repeated prolonged infusions of lower doses or by continuous infusions at still lower infusion rates. However, considering ototoxicity little is, in fact, known about the tolerance of repeated prolonged or continuous infusion in children.

Procedure

Auditory function was monitored along with plasma concentrations of free and total platinum (Pt), and with standard serum parameters (sodium, potassium, calcium, magnesium, phosphate, chloride, and creatinine) in 24 children receiving cisplatin by continuous infusion for the treatment of neuroblastoma and osteosarcoma or by repeated 1 or 6 hr infusions for the treatment of germ cell tumors.

Results

Hearing deteriorated in 10/15 osteosarcoma patients, 2/3 neuroblastoma patients, and 1/6 patients with germ cell tumors. Ototoxicity occurred after cumulative doses between 120 and 360 mg/m2 cisplatin. In osteosarcoma patients, ototoxicity was associated with a comparatively higher mean plasma concentration of free Pt. However, Pt plasma concentrations did not discriminate between patients with or without ototoxicity. In patients experiencing ototoxicity serum creatinine increased by 45% compared to pre‐treatment levels (mean). Serum creatinine increased by 26% in patients without ototoxicity (P < 0.05, Mann–Whitney Rank sum test). Despite standardized hydration, discrete but significant changes of potassium, sodium, magnesium, and phosphate were observed during and/or after cisplatin infusion, which, however, did not discriminate between patients with and without ototoxicity.

Conclusions

While continuous cisplatin infusions are less nephrotoxic than repeated prolonged infusions, we observed considerable ototoxicity in patients treated with continuous cisplatin infusions, which necessitates further evaluations on the tolerance of continuous cisplatin infusions in children. Pediatr Blood Cancer © 2005 Wiley‐Liss, Inc.
Response to vinorelbine and low‐dose cyclophosphamide chemotherapy in two patients with desmoplastic small round cell tumor
Authors: Ferrari Andrea , Grosso Federica , Stacchiotti Silvia , Meazza Cristina , Zaffignani Elena , Marchianò Alfonso , Casanova Michela
Published: November 2005

We report two cases of abdominal desmoplastic small round cell tumor (DSRCT) that showed a clinical response to the vinorelbine/low‐dose cyclophosphamide combination that has been claimed to be effective for rhabdomyosarcoma. This observation may prompt further investigation into the activity of such a regimen in DSRCT patients with recurrent or refractory disease, with a view to a possible future role as maintenance therapy in controlling minimal residual disease in patients who achieve complete remission with intensive induction multimodality therapy. Pediatr Blood Cancer 2007;49:864–866. © 2005 Wiley‐Liss, Inc.
Diagnosis of Burkitt lymphoma in pediatric patients by thoracentesis
Authors: McLean Thomas W. , Farber Rebecca S. , Lewis Zachary T. , Wofford Marcia M. , Pettenati Mark J. , Pranikoff Thomas , Chauvenet Allen R.
Published: November 2005

The diagnosis of Burkitt lymphoma by thoracentesis has been rarely reported in the literature, particularly in children. From 1995 to 2004, we diagnosed six pediatric patients with mature B‐cell neoplasms using thoracentesis as the initial diagnostic procedure. The cytology, immunophenotyping, and cytogenetic results of the pleural fluid cells were consistent with mature B‐cell malignancies. We conclude that thoracentesis for the diagnosis of Burkitt lymphoma in children is safe, fast, and accurate. It should be strongly considered as an initial diagnostic procedure for pediatric patients with pleural effusions who are suspected of having B‐cell malignancies. Pediatr Blood Cancer 2007;49:90–92. © 2005 Wiley‐Liss, Inc.
Minimal residual disease (MRD) measurement as a tool to compare the efficacy of chemotherapeutic drug regimens using Escherichia Coli‐asparaginase or Erwinia‐asparaginase in childhood acute lymphoblastic leukemia (ALL)
Authors: Kwok Cecilia Sze , Kham Shirley Kow , Ariffin Hany , Lin Hai Peng , Quah Thuan Chong , Yeoh Allen Eng
Published: November 2005

Background

L‐asparaginase is a crucial drug in childhood acute lymphoblastic leukemia (ALL) induction therapy, but much debate remains regarding the optimal formulation and dosage. As minimal residual disease (MRD) can accurately measure extremely low levels of lymphoblasts, it is a sensitive reflection of leukemia cell kill. We utilized MRD to compare the efficacy of Erwinia‐asparaginase (Erwinia‐asp) and E. coli‐asparaginase (E. coli‐asp) during induction therapy for childhood ALL.

Procedure

Of 116 precursor‐B ALL patients, 22 were treated with Erwinia‐asp, 90 with E. coli‐asp, and 4 were switched from E. coli‐asp to Erwinia‐asp. MRD levels at the end of induction were analyzed for 90 patients (Erwinia‐asp = 16; E. coli‐asp = 74). Patients were stratified into MRD ≥10−2, between 10−2–10−4 and ≤10−4. Toxicity information during induction was available for 110 patients.

Results

MRD was the only significant prognosticator compared to conventional criteria. Patients treated with Erwinia‐asp were 6.7 times more likely to have MRD levels ≥10−2 (P = 0.031), reflecting slower lymphoblast clearance. While non‐asparaginase related toxicities were similar in both groups, more E. coli‐asp patients experienced severe asparaginase‐related toxicity.

Conclusion

E. coli‐asp is superior to Erwinia‐asp in childhood ALL induction. Although E. coli‐asp is more toxic, this is balanced by better response to therapy. Early response to treatment as measured by MRD is a direct reflection of leukemic cell kill and is a significant prognosticator of eventual outcome, making it a good surrogate marker to evaluate the efficacy of induction drugs in childhood ALL. Pediatr Blood Cancer 2006;47:299–304. © 2005 Wiley‐Liss, Inc.
Autologous transplantation of CD133 selected hematopoietic progenitor cells for treatment of relapsed acute lymphoblastic leukemia
Authors: Barfield R.C. , Hale G.A. , Burnette K. , Behm F.G. , Knapp K. , Eldridge P. , Handgretinger R.
Published: November 2005

A 21‐year‐old white male with relapsed acute lymphoblastic leukemia (ALL) developed an invasive Zygomycosis infection 3 weeks after beginning re‐induction chemotherapy. Because of the high risk of fatal recurrence of the fungal infection, neither long‐term maintenance chemotherapy nor allogeneic hematopoietic stem cell transplant (HSCT) was considered appropriate. Because his ALL blasts expressed CD34 but lacked CD133, he received a CD133 selected autologous graft following high‐dose consolidation chemotherapy. The patient survives in remission 19 months after HSCT. Pediatr Blood Cancer 2007;48:349–353. © 2005 Wiley‐Liss, Inc.
Crystallization and melting behavior of multi‐walled carbon nanotube‐reinforced nylon‐6 composites
Authors: Phang In Yee , Ma Jianhua , Shen Lu , Liu Tianxi , Zhang Wei‐De
Published: November 2005

The crystallization and melting behavior of neat nylon‐6 (PA6) and multi‐walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt‐compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs composites instead of a single exotherm (TCC, 1) for the neat matrix. The formation of the higher‐temperature exotherm TCC, 2 is closely related to the addition of MWNTs. X‐ray diffraction (XRD) results indicate that only the α‐phase crystalline structure is formed upon incorporating MWNTs into PA6 matrix, independently of the cooling rate and annealing conditions. These observations are significantly different from those for PA6 matrix, where the increase in cooling rate or decrease in annealing temperature results in the crystal transformation from α‐phase to γ‐phase. The crystallization behavior of PA6/MWNTs composites is also significantly different from those reported in PA6/nanoclay systems, probably due to the difference in nanofiller geometry between one‐dimensional MWNTs and two‐dimensional nanoclay platelets. The nucleation sites provided by carbon nanotubes seem to be favorable to the formation of thermodynamically stable α‐phase crystals of PA6. The dominant α‐phase crystals in PA6/MWNTs composites may play an important role in the remarkable enhancement of mechanical properties. Copyright © 2005 Society of Chemical Industry
Synthesis of unimolecular reversed micelle consisting of a poly(L‐lactide) shell and hyperbranched D‐mannan core
Authors: Satoh Toshifumi , Tamaki Masaki , Kitajyo Yoshikazu , Maeda Takahiro , Ishihara Hiroyuki , Imai Tomoko , Kaga Harumi , Kakuchi Toyoji
Published: November 2005

A novel biodegradable unimolecular reversed micelle consisting of a poly(L‐lactide) (PLA) shell and a hyperbranched D‐mannan (HBM) core, that is, a chestnut‐shaped polymer (PLA–HBM), was synthesized by the polymerization of L‐lactide on HBM with 4‐(dimethylamino)pyridine (DMAP) as the catalyst. The obtained polymers were soluble in dimethyl sulfoxide, tetrahydrofuran, and chloroform but insoluble in H2O. The molecular weights of the PLA chain on PLA–HBM tended to increase with increasing polymerization time. The number of PLA chains on PLA–HBM could be controlled by the ratio of DMAP to the sugar unit in HBM. The obtained copolymer, PLA–HBM, acted as a unimolecular reversed micelle with an encapsulation ability toward the hydrophilic molecule. In addition, the entrapped hydrophilic molecules were slowly released from the core of PLA–HBM, and the release rate was accelerated by the breaking of the PLA chains of the shell when proteinase K as a hydrolase of PLA was used. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 406–413, 2006
Synthesis and interfacial behaviors of amphiphilic poly(oxypropylene) amidoacids
Authors: Wei Kuan‐Liang , Hung Fei‐Yu , Lin Jiang‐Jen
Published: November 2005

A series of hydrophobic poly(oxypropylene) (POP)‐backboned and hydrophilic poly(oxyethylene)‐backboned amidoacids and imidoacids were prepared through the reaction of poly(oxyalkylene) diamines and trimellitic anhydride (TMA) under mild conditions. The synthesized copolymers were characterized with nuclear magnetic resonance and Fourier transform infrared. Their ability to lower the water surface tension and toluene/water interfacial tension was measured and correlated with the hydrophobic/hydrophilic balance with multiple sodium carboxylate functionalities. The specific POP2000/TMA copolymers, consisting of a 2000 g/mol POP segment and multiple amidoacid functionalities, enabled the demonstration of a strong surfactant tendency and a critical micelle concentration at 0.1 wt %. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 646–652, 2006
Syntheses and gas transport properties of polyarylates based on isophthalic and terephthalic acids and mixtures of bisphenol A and 1, 1 bi‐2‐naphthol
Authors: Villegas‐Coss I. , Ruiz‐Treviño F. A. , Hernández‐López S.
Published: November 2005

Polyarylates based on isophthalic (IA) and terephthalic (TA) acids and an equimolar mixture of the diols Bisphenol A (BPA) and 1,1 bi‐2‐naphthol (BN) were synthesized to produce BPA‐BN/IA and BPA‐BN/TA polymers and to measure their gas permeability coefficients, P(i), at several pressures and 35 °C, to the gases O2, N2, CH4, and CO2. For the BPA‐BN/IA membranes, at a 2 atm up‐stream pressure, the P(O2) and P(CO2) are 0.93 and 4.0 Barrers with O2/N2 and CO2/CH4 ideal separation factors of 6.7 and 27. For the BPA‐BN/TA, at a 2 atm up‐stream pressure, the P(O2) and P(CO2) are 2.0 and 9.9 Barrers with O2/N2 and CO2/CH4 ideal separation factors of 5.6 and 21. Comparing the selectivity–permeability balance of properties shown by the BPA/TA membranes with that shown by the copolymer BPA‐BN/TA, the balance moves in the direction of higher selectivity and lower permeability because of the incorporation of BN, which is a more rigid monomer than BPA. However, when the balance of properties for the pair O2/N2 shown by BPA‐BN/TA is compared with the one shown by other membranes such as those based on mixtures of diols and diacids, that is the bisphenol A‐naphthalene/I‐T polymers reported in the literature, the balance moves up and to the right of the typical selectivity–permeability trade‐off observed in the BPA‐polyarylate family. Thus, simultaneous incorporations of flexible and rigid monomers in both the diols and the diacids lead to more productive and more selective membranes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 256–263, 2006