bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydroxyapatite moldable formulation using natural rubber latex as binder
Authors: Sailaja G. S. , Ramesh P. , Varma H. K.
Published: December 2006

A simple but efficient processing method for shaping intricate bioceramic green bodies has been developed by using natural rubber latex as binder. Different shapes of hydroxyapatite Ca10(PO4)6(OH)2 (HAP) were molded from a composite formulation containing wet precipitated HAP, natural rubber latex (NRL), and a stabilizer. On controlled heat treatment followed by sintering, dense shapes of HAP contours were obtained. The thermal degradation profile of HAP–NRL composites shows that NRL degrades slowly without any abrupt exotherm. The results of energy dispersive X‐ray analysis together with inductively coupled plasma (ICP) analysis indicate that the inorganic residue of NRL does not contain any heavy element. The sintered density of the samples increased with increased HAP content in the formulation and percentage shrinkage reduced accordingly. On varying the HAP content in the formulation from 35 to 95 wt %, the compositions with 85, 90, 92, and 95 wt % HAP showed better flexural strength in the range 40–54 MPa and a flexural modulus value in the range 36–50 GPa. The fracture morphology, as observed by the scanning electron microscope confirms that with increased HAP content in the formulation the sample microstructure attains higher uniformity. The Vickers microhardness for the samples sintered at two different temperatures (1150 and 1250°C) showed that hardness increases with increase in the sintering temperature with a maximum for the highest HAP loaded formulation. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2006.
Evaluation of DBM/AM composite as a graft substitute for posterolateral lumbar fusion
Authors: Qiu Qing‐Qing , Shih Mei‐Shu , Stock Kimberly , Panzitta Teri , Murphy Patricia A. , Roesch Sana C. , Connor Jerome
Published: December 2006

Demineralized bone matrix (DBM) has been investigated as a bone graft substitute for spinal fusion with less morbidity. Various carriers have been added to DBM to enhance its handling characteristics. This study investigates the spinal fusion induced by a composite of DBM and acellular dermal matrix (AM) in comparison with autologous bone in an athymic rat spinal fusion model. Single‐level intertransverse process fusions were performed in 60 athymic nude rats grafted with 2 mL/kg of DBM/AM composite, AM alone, or autologous bone. Fusion was assessed at 6 weeks by radiography, manual palpation, and histology. At 6 weeks, 70% of the animals from the DBM/AM composite group exhibited complete spine fusion, whereas 35% from the autologous bone group and 20% from AM group showed bridging with some gaps. The DBM/AM composite induced a significantly higher fusion rate than both the autologous bone and AM groups (p << 0.001) in all measured parameters. The current study demonstrated that using DBM/AM composite can have more robust fusion than autologous bone at 6 weeks in an athymic rat spinal fusion model. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2006.
Role of indenter material and size in veneer failure of brittle layer structures
Authors: Bhowmick Sanjit , Meléndez‐Martínez Juan José , Hermann Ilja , Zhang Yu , Lawn Brian R.
Published: December 2006

The roles of indenter material and size in the failure of brittle veneer layers in all‐ceramic crown‐like structures are studied. Glass veneer layers 1 mm thick bonded to alumina layers 0.5 mm thick on polycarbonate bases (representative of porcelain/ceramic‐core/dentin) are subject to cyclic contact loading with spherical indenters in water (representative of occlusal biting environment). Two indenter materials—glass and tungsten carbide—and three indenter radii—1.6, 5.0, and 12.5 mm—are investigated in the tests. A video camera is used to follow the near‐contact initiation and subsequent downward propagation of cone cracks through the veneer layer to the core interface, at which point the specimen is considered to have failed. Both indenter material and indenter radius have some effect on the critical loads to initiate cracks within the local Hertzian contact field, but the influence of modulus is weaker. The critical loads to take the veneer to failure are relatively insensitive to either of these indenter variables, since the bulk of the cone crack propagation takes place in the contact far field. Clinical implications of the results are considered, including the issue of single‐cycle overload versus low‐load cyclic fatigue and changes in fracture mode with loading conditions. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2006.
Three new distal tephras in sediments spanning the Last Glacial–Interglacial Transition in Scotland
Authors: Pyne‐O'Donnell Sean D. F.
Published: December 2006

Three new microtephras are reported from a number of lake sites from the Inner Hebrides and Scottish mainland. One occurs stratigrapically in the middle of Greenland Interstadial 1 (GI‐1) and has been named the Penifiler Tephra. It is rhyolitic and possesses a geochemical signature that is very similar to that of the Borrobol Tephra, which also occurs in three of the sequences reported here, but which lies close to the lower boundary of GI‐1. The second occurs stratigraphically in the early Holocene below the Saksunarvatn Ash and is named the Ashik Tephra. This tephra is geochemically bimodal, with a rhyolitic component comparable to the An Druim Tephra that occurs later in the Holocene, and a basaltic component which is similar to the Saksunarvatn Ash. A third tephra occurs stratigraphically above the Saksunarvatn Ash and is provisionally named the Breakish Tephra. The consistent inter‐site correlation demonstrated for these new tephras at several sites enhances the regional tephrostratigraphic framework, and increases the potential for correlating palaeoenvironmental events during GI‐1 and the early Holocene. However, the occurrence of multiple tephras with similar geochemistry in close stratigraphic and temporal proximity has implications for the rigour with which tephrostratigraphic investigations must be performed. Copyright © 2006 John Wiley & Sons, Ltd.
Fodder production and soil health with conjunctive use of saline and good quality water in ustipsamments of a semi‐arid region
Authors: Yadav R. K. , Singh S. P. , Lal D. , Kumar A.
Published: December 2006

Food and fodder shortage in arid and semi‐arid regions force farmers to use marginal quality water for meeting the water requirement of crops which result in low quality, reduced production and an adverse impact on soil properties. A field study on loamy‐sand (Hyperthermic Typic Ustipsamments) saline soil was conducted during 1999–2001 at Central Institute for Research on Buffaloes, Hisar. This involved assessment of effects of conjunctive use of saline water, EC = 4·6–7·4 dSm−1, SAR = 14–22 ((mmol−1)½with good quality water on five fodder crop rotations: oat‐sorghum (Avena sativa‐–Sorghum bicolor), rye grass–sorghum (Loleum rigidum—Sorghum bicolor), Egyptian clover—sorghum (Trifoleum alexandrinum—Sorghum bicolor), Persian clover—sorghum (Trifoleum resupinatum—Sorghum bicolor) and Indian clover–sorghum (Melilotus indica—Sorghum bicolor) and certain soil properties associated with it. Leguminous winter fodder crops were more sensitive to poor quality water use. Reductions in fodder yield with use of saline water alone throughout season were 85, 68, 54, 42, 36 and 26 per cent in Indian clover, Egyptian clover, Persian clover, oat, rye grass and sorghum respectively as compared to good quality water. Leguminous fodder crops produced protein rich (12–14 per cent) and low fibre (18–20 per cent) fodder as compared to poor quality grassy fodder under good quality water irrigation but their quality deteriorated when saline water was used. These leguminous crops accumulated proportionately higher Na+(1·58 per cent) resulting in adverse impact on their growth as compared to grassy fodder crops. Higher soil salinity (12·2 dSm−1), SAR = 20 (mmol−1)½was recorded with saline water irrigation; and slight adverse impact was noticed on infiltration rate and contents of water dispersible clay. Alternate cyclic use of canal and saline water could be an option for fodder production under such conditions. Copyright © 2006 John Wiley & Sons, Ltd.
Participatory soil and water conservation planning using a financial analysis tool in the West Usambara highlands of Tanzania
Authors: Tenge A. J. , Okoba B. O. , Sterk G.
Published: December 2006

Despite decades of soil and water conservation (SWC) efforts in Tanzania, the adoption of the recommended SWC measures by farmers is minimal. In the past, SWC plans did not incorporate farmers' knowledge, and the economics of SWC was not given much attention at the planning stage. This research evaluated the applicability of two tools for participatory soil erosion mapping using farmers' indicators of soil erosion and financial analysis of SWC measures at the planning stage. The two tools were evaluated in Kwalei catchment in the West Usambara highlands, Tanzania. The participatory soil erosion‐mapping tool uses farmers' indicators of soil erosion to identify, classify and map soil erosion at the catchment level. The financial analysis tool involves farmers in a stepwise analysis of the costs and benefits of SWC measures before the implementation. The erosion‐mapping tool increased farmers' awareness on the severity of soil erosion problems, and they realised the need for SWC plans at both field and catchment scales. With the financial analysis tool farmers participated in the cost and benefits analysis and were able to select SWC options that were feasible under their socio‐economic situation. The two tools were able to demonstrate that farmers' participation in SWC planning increases the acceptance of SWC measures because they solve problems that are perceived by themselves. The financial analysis tool demonstrated how farmers could make selection of SWC measures that are feasible under their biophysical and economic condition if they are informed about the costs and benefits. Copyright © 2006 John Wiley & Sons, Ltd.
On the point spectrum of ℋ︁–2‐singular perturbations
Authors: Albeverio Sergio , Dudkin Mykola , Konstantinov Alexei , Koshmanenko Volodymyr
Published: December 2006

We prove that for any self‐adjoint operator A in a separable Hilbert space ℋ︁ and a given countable set Λ = {λ i }i ∈ℕ of real numbers, there exist ℋ︁–2‐singular perturbations Ã of A such that Λ ⊂ σ p (Ã). In particular, if Λ = {λ 1,…, λ n } is finite, then the operator Ã solving the eigenvalues problem, Ã ψ k = λ k ψ k , k = 1,…, n, is uniquely defined by a given set of orthonormal vectors {ψ k }n k =1 satisfying the condition span {ψ k }n k =1 ∩ dom (|A |1/2) = {0}. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cusps and codes
Authors: Barth Wolf P. , Rams Sławomir
Published: December 2006

We study a construction, which produces surfaces Y ⊂ ℙ3(ℂ) with cusps. For example we obtain surfaces of degree six with 18, 24 or 27 three‐divisible cusps. For sextics in a particular family of surfaces with up to 30 cusps the codes of these sets of cusps are determined explicitly. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Co‐rigidity of groups, von Neumann algebras and Kac algebras
Authors: Heo Jaeseong
Published: December 2006

In this paper, we consider a generalization of property T of Kazhdan for groups and property T of Connes for von Neumann algebras. We introduce another relative property T for groups corresponding to co‐rigidity for von Neumann algebras, which is different from relative property T of Margulis. We investigate the connection between a pair of von Neumann algebras and a pair of their commutants with respect to co‐rigidity. We define relative property T and co‐rigidity for a pair of Kac algebras as the generalizations of relative property T and co‐rigidity for groups. We show that the tensor product of two Kac algebras has property T if and only if two Kac algebras all have property T. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Branching rules for Hecke algebras of type Dn
Authors: Hu Jun
Published: December 2006

In this paper we study the branching problems for the Hecke algebra ℋ︁(D n ) of type D n . We explicitly describe the decompositions into irreducible modules of the socle of the restriction of each irreducible ℋ︁(D n )‐representation to ℋ︁(D n –1) by using the corresponding results for type B Hecke algebras. In particular, we show that any such restrictions are always multiplicity free. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A notion of Euler characteristic for fractals
Authors: Llorente Marta , Winter Steffen
Published: December 2006

A notion of (average) fractal Euler number for subsets of ℝd with infinite singular complexes is introduced by means of rescaled Euler numbers of infinitesimal ε ‐neighbourhoods. For certain classes of self‐similar sets we calculate the associated Euler exponent and the (average) fractal Euler number with the help of the Renewal theorem. Examples like the Sierpinski gasket or carpet are provided. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solutions to some nonlinear parabolic equations in pseudomeasure spaces
Authors: Miao Changxing , Yuan Baoquan
Published: December 2006

In this paper we study the Cauchy problem in pseudomeasure spaces for some nonlinear parabolic equations including nonlinear heat equations, nonlinear hyper‐dissipative equations, generalized nonlinear Hamilton–Jacobi equations, nonlinear hyper‐dissipative equations with convective term and the Ginzburg–Landau equation with third‐order nonlinear growth. We prove the existence, uniqueness and asymptotic stability of the global‐in‐time solutions for small initial data in some pseudomeasure spaces. As a result, the existence and uniqueness of selfsimilar solutions to the equations are obtained. Furthermore, with the self‐similar solutions of the equations, the long time behavior of solutions to the problem are also discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Integrable operators and canonical differential systems
Authors: Sakhnovich Lev
Published: December 2006

In this article we consider a class of integrable operators and investigate its connections with the following theories: the spectral theory of the non‐self‐adjoint operators, the Riemann‐Hilbert problem, the canonical differential systems, the random matrices theory and the limit values of the multiplicative integral. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical and Experimental Investigation of the Production of PMMA‐Based Bone Cement
Authors: Santos Jorge G. F. , Peixoto Luciana S. , Nele Márcio , Melo Príamo A. , Pinto José Carlos
Published: December 2006

Poly(methyl methacrylate) (PMMA)‐based polymers have been extensively used for manufacturing of artificial bone cements for treatment of osteoporosis. A typical bone cement recipe contains methyl methacrylate, which polymerizes in situ during cement application. An inherent problem of this reaction is the high amount of heat released during the cement preparation, which may lead to irreparable damage of living tissues. Optimization of PMMA‐based bone cement (PMMABC) recipes is thus an important step towards safe and reliable clinical usage of these materials. A theoretical and experimental investigation is performed here to unveil the influence of some preparation variables on the production of PMMABC and to allow for future optimization of the PMMABC recipe. It is shown that the degree of mixing of the components of the recipe plays a fundamental role on the development of the temperature profile. For this reason, the PMMABC obtained with the in‐situ blending of PMMA and barium sulfate during the suspension polymerization leads to much better homogeneity of the final test pieces and improved control of the temperature profile.
Modeling Methyl Methacrylate (MMA) Polymerization for Bone Cement Production
Authors: Lemos Lívia , Nele Marcio , Melo Príamo , Pinto José Carlos
Published: December 2006

Bone cements based on poly(methyl methacrylate) (PMMA) have been widely used in orthopedic surgeries for fixation of prostheses and filling of bone defects. Bone cements are produced through in situ and in vivo free radical bulk polymerizations, which are highly exothermic and are subject to strong gel and glass effects. As a consequence, high temperatures may be reached during application. Furthermore, residual monomer usually remains unreacted inside the body and may cause aseptic loosening and tissue damages.1 In a companion work in this volume, it was shown that usual free‐radical polymerization models might effectively describe the bone cement preparation2 and therefore be used for quantitative analysis of the bone cement synthesis. In this work, a theoretical investigation based on a multicell reactor model is performed to study the bone cement production and allow for future optimization of the preparation procedure. It is shown that the degree of solubility of the pre‐polymer powder in the liquid monomer is the most important variable during the bone cement preparation and that this variable should be manipulated for design and control of the operation in real applications.
High Temperature Semibatch Free Radical Copolymerization of Butyl Methacrylate and Styrene
Authors: Li Deheng , Hutchinson Robin A.
Published: December 2006

High temperature starved feed semibatch solution polymerization is used to produce acrylic resins for automotive coatings. These operating conditions promote secondary reactions that have a strong impact on polymerization rate and polymer molecular weight (MW). This study experimentally investigates high temperature semibatch copolymerization of butyl methacrylate and styrene, a system subject to the combined effect of depropagation and penultimate propagation kinetics. A mechanistic model including these complexities is constructed in Predic®. With the termination rate coefficient fit to the semibatch results and all other coefficients taken from independent experiments, the model provides good predictions of monomer conversion and MW. Various representations of copolymer termination kinetics from the literature are compared to the values fit from experiment.
Hydrodynamics in a Gas‐Solids Fluidized Bed Using X‐Ray Fluoroscopy and Pressure Fluctuation Measurements
Authors: Wu Bangyou , He Zhengxing , Kantzas Apostolos , Bellehumeur Céline T. , Kryuchkov Sergey
Published: December 2006

In this work, non‐intrusive techniques were used to characterize the hydrodynamics in a gas‐solids bubbling fluidized bed using polyethylene powder and glass beads of comparable mean diameter (dp = 360 µm) but different density. X‐ray fluoroscopy measurements and pressure fluctuations were performed on a pseudo 2‐dimensional gas‐solids fluidized bed. Bubble properties were captured from X‐ray fluoroscopy measurements. Similarities and differences of flow behavior of the two particle systems were revealed from comparison of bubble properties. Bubble properities normally varied similary with operating conditions for the two particle systems, while bubble sizes for the glass beads system are larger than those for the polyethylene system. Wavelet analysis of pressure fluctuations was applied to investigate the gas and solids phase flow behavior. Multi‐scale flow behavior was extracted from the standard deviation of the decomposed coefficient series. Flow behavior due to particles and bubbles of different sizes were captured at different decomposition levels of pressure fluctuations, which is difficult to know from analysis of the original signal. Results extracted from X‐ray fluoroscopy and pressure fluctuation measurements were consistent, suggesting that conventional pressure fluctuation measurements can be effectively used for investigation of the bubbling behavior.
Dynamic Monte Carlo Simulation of Graft Copolymers Made with ATRP and Metallocene Catalysts
Authors: Al‐Harthi Mamdouh , Soares João B.P. , Simon Leonardo C.
Published: December 2006

The synthesis of polyolefin graft copolymers made with coordination polymerization was studied by dynamic Monte Carlo simulation. Narrow molecular weight distribution macromonomers, containing terminal vinyl groups made with atom‐transfer radical polymerization (ATRP), were incorporated randomly into the polyolefin backbone. In addition to average molecular weights and polydispersity index, the model predicts the complete molecular weight distribution (MWD) and branching density of the graft copolymer. The effect of the concentration of macromonomers on the grafting efficiency was also studied.
Simultaneous Data Reconciliation and Parameter Estimation in Bulk Polypropylene Polymerizations in Real Time
Authors: Prata Diego Martinez , Lima Enrique Luis , Pinto José Carlos
Published: December 2006

This work presents the implementation of a methodology for dynamic data reconciliation and simultaneous estimation of quality and productivity parameters in real time, using data from an industrial bulk Ziegler‐Natta propylene polymerization process. A phenomenological model of the real process, based on mass and energy balances, was developed and implemented for interpretation of actual plant data. The resulting nonlinear dynamic optimization problem was solved using a sequential approach on a time window specifically tuned for the studied process. Despite the essentially isothermal operation conditions, obtained results show that inclusion of energy balance constraints allows for increase of information redundancy and, as a consequence, for computation of better parameter estimates than the ones obtained when the energy balance constraints are not considered (Prata et al., 2005). Examples indicate that the proposed technique can be used very effectively for monitoring of polymer quality and identification of process malfunctions in real time even when laboratory analyses are scarce.
Modeling the Vulcanization of Rubber Blends
Authors: Likozar Blaž , Krajnc Matjaž
Published: December 2006

Kinetics and heat transfer during vulcanization of various blends of polybutadiene (BR) and polyisoprene (NR) were studied simultaneously using mechanistic approach for description of reaction kinetics. Fourier transform infrared spectroscopy (FTIR) was used to study the kinetics of accelerator and retarder chemistry. Differential scanning calorimetry (DSC) and dynamic rheometry were applied in order to retrieve the data for heat transfer modeling during induction period and kinetic modeling throughout the process. Model reaction scheme was based on one of the best possible proposed individual reaction mechanisms. Molecular modeling was applied to differentiate between the reactions of chemically similar species. Physical and chemical model parameters were calculated from the experimental data. A minimum of average rubber heat transfer coefficient was found to be at equal BR and NR weight fractions in the blend while activation energies of crosslinking and reversion reactions increased linearly with increasing BR weight fraction.
Batch and Semicontinuous Styrene–Butadiene Emulsion Copolymerization Reactions
Authors: Filho Aluisio Pinelli , Araujo Odair , Giudici Reinaldo , Sayer Claudia
Published: December 2006

In this work an experimental and simulation study of batch and semicontinuous styrene/butadiene emulsion copolymerization process was developed. The mathematical model combines the classical emulsion copolymerization equations, with mass balances, partitioning of components among all liquid phases, micellar and homogenous nucleation mechanisms and mass transfer equations between liquid and gaseous phases. Simulation results show good agreement with experimental measurements of conversion, average particle diameter and pressure.
Initiation Efficiency Reduction in Semicontinuous Styrene and Butyl Acrylate Emulsion Copolymerization Reactions
Authors: Hirota Wilson H. , Giudici Reinaldo , Sayer Cláudia
Published: December 2006

The decrease of initiation efficiency (radical entry efficiency) during seeded emulsion copolymerizations of styrene and butyl acrylate with different residual monomer reduction strategies was evaluated. Experiments were carried out using 50 and 99wt.% of styrene in monomer feed stream. Simulations were performed with a detailed mathematical model of the process that takes into account the diffusion control of initiation, propagation and termination. Results showed that the radical entry into polymer particles is strongly influenced by the aqueous phase kinetics and by the monomer solubility in aqueous phase. Simulation results were compared to experimental results of residual monomer and showed that the residual monomer content can be reduced by a temperature increase at the end of the polymerization. However, an additional feeding of more initiator, even when combined with such an increase of temperature, did not lead to a smaller residual monomer content due, mainly, the kinetic of termination in aqueous phase and radical anchoring. A model that accounts for the reduction of initiator efficiency (free radical entry efficiency) was successfully used to explain the behavior of the experimental observations and was able to correctly predict the qualitative trends of the effectiveness of different residual monomer reduction strategies.
Dynamics of Foaming of Polystyrene Particles
Authors: Salejova Gabriela , Kosek Juraj
Published: December 2006

September 24, 2006

Summary: In this work, we address the industrially relevant problem of the foaming of expandable polystyrene (PS) impregnated by pentane as a traditional down‐stream processing in the suspension polymerization of styrene. Once the polystyrene foam is formed by means of a proper foaming agent, e.g., pentane or fluoro‐ or chloro‐hydrocarbons, the blowing agent diffuses out from the cellular structure. Environmental efforts call for the reduced consumption of blowing agents. The dynamics of foaming of polystyrene particles was recorded video‐microscopically in our laboratory as the sequence of images of expanding particle located in the small pressure cell placed under the microscope with sufficient depth of focus. The amount of pentane sorbed in PS was controlled by the length of the impregnation period and was determined independently by gravimetric measurements. Strong dependence of the structure of the produced foam and of the foaming dynamics on the amount of sorbed pentane, temperature and particle size is reported and explanations for some observed foaming phenomena are provided.
Bulk Polymerisation or Copolymerisation in a Novel Continuous Kneader Reactor
Authors: Fleury Pierre‐Alain
Published: December 2006

A new type of kneader reactor is proposed for the continuous radical (co‐) polymerisation without solvent, based on the proven design of mature (kneader‐) dryer technology. The reactor has been developed to satisfy all major aspects required for (co‐) polymerisation while maintaining the safety and reliability of the previous mechanical design. The new kneader reactor offers a perfect combination of surface renewal and evaporative cooling to control temperature to high conversion (85 to 95%), even for bulk systems that have a strong gel effect (Trommsdorff's effect) and high exothermicity. The reactor can be tested batch‐wise to optimise the recipe, as shown in this work for bulk free radical polymerisation of methyl methacrylate (MMA). A simulation program was correlated to the experimental batch data to determine the optimum concentrations of initiator and of chain transfer agent to target a given molecular weight of PMMA. Design of a continuous kneader reactor to optimise the conversion as a function of residence time, to eliminate foam formation, and to produce copolymers without composition drift, is also presented.
Continuous Reactor Concepts with Superimposed Secondary Flow – Polymerization Process Intensification
Authors: Pauer Werner , Moritz Hans‐Ulrich
Published: December 2006

Different unconventional continuous polymerization reactor concepts with superimposed secondary flow are presented. Exemplary polymerization reactions and the residence time distributions are discussed. In the case of the Taylor reactor polymerization process intensification is demonstrated by examples of emulsion and micro‐emulsion polymerization which actually results in an increase in space time yield of up to a factor of 50.
Cover Picture: Macromol. Symp. 243/2006
Authors: Salejova Gabriela , Kosek Juraj
Published: December 2006

Cover: PRE VI, held in Halifax, Canada in May 2006, is the 6th in a continuing series of conferences on emerging technologies and scientific advancements in the area of polymer reaction engineering. Key topics discussed included reaction engineered nanocomposites and nanoparticles, production of polymers with controlled architectures, online monitoring of polymerization systems, measurement and modeling of polyolefin particle growth and reactor hydrodynamics, and polymerization process intensification via novel reactor design. The selected contributions in this issue reflect the developing trend of applying reaction engineering principles and skills not only to improvement of polymerization processes, but also to the design and development of new materials. The picture on the cover is an image of an expanding polystyrene particle, taken from the contribution of Salejova and Kosek.
Non‐standard finite difference schemes for multi‐dimensional second‐order systems in non‐smooth mechanics
Authors: Dumont Yves , Lubuma Jean M.‐S.
Published: December 2006

This work is an extension of the paper (Proc. R. Soc. London 2005; 461A:1927–1950) to impact oscillators with more than one degree of freedom. Given the complex and even chaotic behaviour of these non‐smooth mechanical systems, it is essential to incorporate their qualitative physical properties, such as the impact law and the frequencies of the systems, into the envisaged numerical methods if the latter is to be reliable. Based on this strategy, we design several non‐standard finite difference schemes. Apart from their excellent error bounds and unconditional stability, the schemes are analysed for their efficiency to preserve some important physical properties of the systems including, among others, the conservation of energy between consecutive impact times, the periodicity of the motion and the boundedness of the solutions. Numerical simulations that support the theory are provided. Copyright © 2006 John Wiley & Sons, Ltd.
1‐Cyclohepta‐2,4,6‐trienyl‐selanes—a77Se NMR study: Indirect nuclear77Se13C spin–spin coupling constants and application of density functional theory (DFT) calculations
Authors: Wrackmeyer Bernd , Hernández Zureima García , Herberhold Max
Published: December 2006

1‐Cyclohepta‐2,4,6‐trienyl‐selanes Se(C7H7)2(2c), RSeC7H7with R = Bu,tBu, Ph, 4‐FC6H4(12a,b,c,d) were prepared by the reaction of the corresponding silanes, Si(SeMe3)2and RSeSiMe3, respectively, with tropylium bromide C7H7Br. In spite of the low stability of the selanes even in dilute solutions and at low temperature, they could be characterised by their1H,13C and77Se NMR parameters. Coupling constants1J(77Se,13C) were measured and calculated by DFT methods at the B3LYP/6‐311+G(d,p) level of theory. The comparison of experimental and calculated coupling constants1J(77Se,13C) included numerous selenium carbon compounds with largely different SeC bonds, revealing a satisfactory agreement. Both the spin–dipole (SD) and the paramagnetic spin‐orbital (PSO) terms contributed significantly to the spin–spin coupling interaction, in addition to the Fermi contact (FC) term. Copyright © 2006 John Wiley & Sons, Ltd.
The clinical aspects of newborn screening: Importance of newborn screening follow‐up
Authors: James Philip M. , Levy Harvey L.
Published: December 2006

The aim of newborn screening is to identify presymptomatic healthy infants that will develop significant metabolic or endocrine derangements if left undiagnosed and untreated. The goal of ultimately reducing or eliminating irreversible sequelae is reached by maximizing test sensitivity of the primary newborn screening that measures specific analytes by a number of methodologies. Differentiation of true from false negatives is accomplished by the test specificity. This review discusses disorders for which, in general, there are available therapies and that are detected by routine and expanded newborn screening. Recommendations are presented for evaluation by a primary care physician, with confirmation by a metabolic or endocrinology specialist. Disorders are organized in tabular format by class of pathway or analyte, with attention to typical clinical presentations, confirmatory biochemical and molecular tests, and therapies. There are numerous challenges in clinical follow‐up, including diagnosis and appropriate understanding of the consequences of the disorders. The data required to meet these challenges can be acquired only by large scale longitudinal comprehensive studies of outcome in children identified by newborn screening. Only with such data can newborn screening fully serve families. © 2006 Wiley‐Liss, Inc. MRDD Research Reviews 2006;12:246–254.
Pilot programs in newborn screening
Authors: Pass Kenneth , Green Nancy S. , Lorey Fred , Sherwin John , Comeau Anne Marie
Published: December 2006

The term “pilot study” has been used over the years to describe the evaluation of the many elements involved in deciding whether a proposed condition should be added to a newborn screening (NBS) panel, and until recently, was unilaterally used to describe the evaluation of the assay to be used before the condition was officially adopted by a state for its newborn screening panel. Since Guthrie's introduction of screening for PKU, each time a new condition was added to the panel, the screening assay itself was validated through a population‐based trial, in which the test was performed with de‐identified samples to avoid association between the test result and the infant. This is considered by the laboratory as the “pilot phase” of adding a new condition. To advance the science of NBS, especially to accommodate new technologies that may provide new types of information (genetic versus physiological) for each new condition, pilot programs are essential. Involvement of the clinical community serves to improve these evaluations and provides the needed clinical validation of decisions made as a result of it. This paper describes the historical context of pilot programs in population‐based NBS that utilize laboratory‐based markers as indicators of concern; specifically, three applications that demonstrate different approaches to the use of pilots in adding conditions to a NBS panel are described. © 2006 Wiley‐Liss, Inc. MRDD Research Reviews 2006;12:293–300.
Universal newborn screening and adverse medical outcomes: A historical note
Authors: Brosco Jeffrey P. , Seider Michael I. , Dunn Angela C.
Published: December 2006

Universal newborn screening programs for metabolic disorders are typically described as a triumph of medicine and public policy in the US over the last 50 years. Advances in science and technology, including the Human Genome Project, offer the opportunity to expand universal newborn screening programs to include many additional metabolic and genetic conditions. Although the benefits of such screening programs appear to outweigh their costs, some critics have claimed that historical examples of inadvertent harm ensuing from false‐positive screening results and subsequent inappropriate medical treatment should make us wary of expanding universal newborn screening. In this essay, we report the results of a review of the published literature to assess whether the extension of screening from at risk populations to all newborns led to substantial morbidity and mortality from misguided medical treatment. We provide a historical overview of universal newborn screening programs in the United States, and then focus on six early NBS programs: congenital hypothyroidism, phenylketonuria, congenital adrenal hyperplasia, galactosemia, sickle cell disease, and maple syrup urine disease. Our comprehensive search of published sources did not reveal a widespread problem of harm ensuing from medical treatment of children with false positive screening test results. © 2006 Wiley‐Liss, Inc. MRDD Research Reviews 2006;12:262–269.
The role of National Library of Medicine® web sites in newborn screening education
Authors: Fomous Cathy , Miller Naomi
Published: December 2006

Expanded newborn screening programs and subsequent detection of rare genetic disorders challenge parents and their medical providers to learn about the treatment and management of these disorders. Many people seek medical information on the Internet but may encounter requests for registration or fees, or find that resources are out of date, difficult to understand, or buried in advertisements. The U.S. National Library of Medicine (NLM), a component of the National Institutes of Health, provides web‐based resources that address the challenges of newborn screening education. These resources include MedlinePlus®, Genetics Home Reference™, ClinicalTrials.gov, and PubMed®. NLM websites are not commercial, do not require registration or fees, and provide varied levels of information for a continuum of audiences from low‐literacy consumers to health professionals. Using phenylketonuria as an example, this study describes the information that parents and their medical providers can find through NLM resources. NLM has embraced the digital age and provides the public with reliable, accurate, and up‐to‐date educational materials. © 2006 Wiley‐Liss, Inc. MRDD Research Reviews 2006;12:305–312.
Current status of newborn screening: Decision‐making about the conditions to include in screening programs
Authors: Watson Michael S.
Published: December 2006

Newborn screening is considered a highly successful public health program that has resulted in the reduction of mortality, mental retardation, and other serious disabilities in thousands of children since the introduction of screening for phenylketonuria (PKU) in the 1960s. Programs are based in state public health departments such that each state independently reaches decisions as to which conditions should be mandated for inclusion in programs, leading to considerable variability among the states as to what is being screened. New technologies and knowledge of the genetics of many conditions have greatly expanded the number of conditions with potential for inclusion in newborn screening. © 2006 Wiley‐Liss, Inc. MRDD Research Reviews 2006;12:230–235.
An extension of Hill's three‐component model to include different fibre types in finite element modelling of muscle
Authors: Stojanovic B. , Kojic M. , Rosic M. , Tsui C. P. , Tang C. Y.
Published: December 2006

Most of the proposed versions of the Hill's model use a sliding‐element theory, considering a single sarcomere. However, a muscle represents a collection of different fibre types with a large range in contractile properties among them. An extension of Hill's three‐component model is proposed here to take into account different fibre types. We present a model consisting of a number of sarcomeras of different types coupled in parallel with the connective tissue. Each sarcomere is modelled by one non‐linear elastic element connected in series with one non‐linear contractile element.

Using the finite element method, in an incremental‐iterative scheme of calculating equilibrium configurations of a muscle, the key step is the determination of stresses corresponding to strain increments. The stress calculation procedure for the extended Hill's model is reduced to the solution of a number of independent non‐linear equations with respect to the stretch increments of the serial elastic elements in each sarcomere.

Since the distribution of the specific fibre type is non‐uniform over the muscle volume, we have material heterogeneity which we modelled by using the so‐called ‘Generalized Isoparametric Element Formulation’ for functionally graded materials (FGMs).

The proposed computational scheme is built in our FE package PAK, so that muscles of complex three‐dimensional shapes can be modelled. In numerical examples, we illustrate the main characteristics of the developed numerical model and some possibilities of realistic modelling of muscle functioning. Copyright © 2006 John Wiley & Sons, Ltd.
Longitudinal evaluation of early and late anthracycline cardiotoxicity in children with AML
Authors: Creutzig Ursula , Diekamp Sylke , Zimmermann Martin , Reinhardt Dirk
Published: December 2006

Background

Anthracyclines are effective antineoplastic drugs in acute myelogenous leukemia (AML). However, their use is limited by cardiomyopathy, which occurs in children already at cumulative doses of 300 mg/m2 (given as daunorubicin equivalent).

Procedure

To evaluate anthracycline‐associated cardiomyopathy in pediatric AML‐patients, the incidence of early and late (>1 year after intensive AML chemotherapy) clinical and subclinical cardiotoxicity was analyzed out of a total of 1,207 patients <18 years treated between 1993 and 2003 in trials AML‐BFM93/98: 1,010 protocol patients with de novo AML, 121 with Down syndrome (DS)‐AML, and 76 with secondary AML. The cumulative dose of anthracyclines was generally risk‐adapted: 300–450 mg/m2 using 1–4‐hr infusions of anthracyclines with the assumed lowest cardiotoxic potential. Eight hundred eighty‐five patients (73%) were eligible for the analysis of early and 547 (45%) of late cardiotoxicity (1,399 follow‐up data).

Results

Thirty‐eight patients (4.3%), including 3 DS‐AML and 1 secondary AML, suffered from early cardiomyopathy. After 5 years, four patients showed temporarily or persistently a reduced shortening fraction, which led to death in one DS‐AML patient. Including these 4 patients, late cardiomyopathy was seen in 16 patients (cumulative incidence after 11 years: 5% ± 1%). Nine patients (2.5 ± 1%) showed clinical symptoms, five of them had persistent abnormal shortening fraction. Late subclinical cardiomyopathy occurred temporarily in seven patients. Late clinical cardiomyopathy mainly affected patients with a second anthracycline therapy (secondary malignancy) and those with early cardiotoxicity.

Conclusion

In spite of a highly intensive and effective treatment, the frequency of anthracycline‐associated cardiomyopathy was low in the AML‐BFM studies. Pediatr Blood Cancer 2007;48:651–662. © 2006 Wiley‐Liss, Inc.
MRI findings in Shwachman diamond syndrome
Authors: Ruggiero Antonio , Molinari Francesco , Coccia Paola , Attinà Giorgio , Maurizi Palma , Riccardi Riccardo , Bonomo Lorenzo
Published: December 2006

Shwachman Diamond Syndrome (SDS) is a rare congenital disorder characterized by pancreatic insufficiency, bone marrow dysfunction, and skeletal changes. Because of the heterogeneous clinical presentation and the limits of laboratory tests that assess pancreatic insufficiency, the diagnosis of SDS can be challenging. Pancreatic lipomatosis, a typical feature of this syndrome, is also difficult to assess by direct tissue sampling. In these circumstances, magnetic resonance imaging (MRI) provides a readily available, noninvasive tool to evaluate the pancreatic fat content. We report a case of a 12‐month‐old male in which abdominal MRI was used to confirm the clinical diagnosis of SDS. Pediatr Blood Cancer 2008;50:352–354. © 2006 Wiley‐Liss, Inc.
Current awareness: Pharmacoepidemiology and drug safety
Authors:   John Wiley & Sons, Ltd.
Published: December 2006

In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of pharmacoepidemiology and drug safety. Each bibliography is divided into 20 sections: 1 Books, Reviews & Symposia; 2 General; 3 Anti‐infective Agents; 4 Cardiovascular System Agents; 5 CNS Depressive Agents; 6 Non‐steroidal Anti‐inflammatory Agents; 7 CNS Agents; 8 Anti‐neoplastic Agents; 9 Haematological Agents; 10 Neuroregulator‐Blocking Agents; 11 Dermatological Agents; 12 Immunosuppressive Agents; 13 Autonomic Agents; 14 Respiratory System Agents; 15 Neuromuscular Agents; 16 Reproductive System Agents; 17 Gastrointestinal System Agents; 18 Anti‐inflammatory Agents ‐ Steroidal; 19 Teratogens/fetal exposure; 20 Others. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted.
Moisture absorption effects on the thermal and mechanical properties of wood flour/linseed oil resin composites
Authors: Mosiewicki Mirna A , Borrajo Julio , Aranguren Mirta I
Published: December 2006

The thermal and mechanical behavior of new natural polymeric composite materials after exposure to humid environments must be well known and understood in order to predict their performance in final applications. For this reason, composites made from unsaturated polyesters based on linseed oil and filled with wood flour were exposed to environments of different relative humidities and their final properties were measured. In general, the equilibrium moisture content increased as the wood flour percentage increased. Dynamic mechanical tests performed in temperature scan mode were carried out in order to monitor the changes resulting from moisture absorption on the main transition temperature of the matrix (Tα). The temperature of this transition decreased as the amount of absorbed water increased, but the effect was partially reversible by re‐drying the samples. The mechanical properties were also strongly affected by moisture. The flexural modulus and ultimate stress of the composites decreased after equilibration in humid environments. Copyright © 2006 Society of Chemical Industry
High‐pressure infrared absorption spectroscopy of poly(methyl methacrylate)
Authors: Emmons E. D. , Kraus R. G. , Duvvuri Srividya S. , Thompson J. S. , Covington A. M.
Published: December 2006

High‐pressure Fourier‐transform infrared absorption spectroscopy was used to study poly(methyl methacrylate) in a diamond anvil cell at pressures up to ≈8 GPa. The positions of the vibrational modes were measured as a function of pressure. The data were analyzed to determine mode Grüneisen parameters and bond anharmonicities. The vibrational modes were analyzed using models that include both volume independent and dependent Grüneisen parameters, and the different models were compared. The vibrational frequency shifts as a function of pressure were found to be consistent with those measured for similar types of bonds in other molecules. This data may find applications where polymers are subjected to large pressures, including shock compression experiments. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 358–367, 2007
Poly(propylene isophthalate), poly(propylene succinate), and their random copolymers: Synthesis and thermal properties
Authors: Soccio M. , Finelli L. , Lotti N. , Gazzano M. , Munari A.
Published: December 2006

Poly(propylene isophthalate) (PPI), poly(propylene succinate) (PPS), and poly(propylene isophthalate/succinate) (PPI‐PPS) random copolymers were synthesized and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by TGA and DSC. All the polymers showed a good thermal stability. At room temperature, they appeared as semicrystalline materials, except 20PPI‐PPS and 30PPI‐PPS: the main effect of copolymerization was a lowering in the amount of crystallinity and a decrease of Tm with respect to homopolymers. A crystalline phase of PPI and PPS was evidenced at high content of PI or PS units, respectively. Amorphous samples were obtained after melt quenching and an increment of Tg, with the increment of PI units, was observed. This behavior was explained as due to the presence of stiff phenylene groups. The Wood equation described well Tg‐composition data. Lastly, the presence of a rigid‐amorphous phase was evidenced in copolymers, differently from the two homopolymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 310–321, 2007.