bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Technique for Preparing a Filled Type of Polymeric Gradient Material
Authors: Zhu Yong‐Bin , Ning Nan‐ying , Sun Yang , Zhang Qin , Fu Qiang
Published: November 2006

Summary: So‐called functionally gradient materials have received increased attention as a new type of composite whose microelements, including composition and structure, change spatially to optimize the gradient properties for a specific application. In this study, a new technique for continuously preparing a filled type of PGM was investigated through co‐extrusion/gradient distribution/2‐dimensional mixing with conventional polymeric material processing facilities. The processing line from co‐extrusion, gradient distribution to 2‐dimensional mixing was fulfilled by two extruders, a gradient distribution unit and 2‐dimensional mixing units. The gradient distribution unit and 2‐dimensional mixing units were designed separately in our group. As an example, a PE/GB PGM was prepared by using this new technique. The gradient variation of composition along the sample thickness direction was studied by TG and SEM. The TG results indicated that a gradient variation of the content of GB was formed along the thickness of the sample. The direct gradient distribution of GB came from SEM observation, which showed an increased stacking density of GB along the sample thickness. Experimental results indicated that the processing method with co‐extrusion/gradient distribution/2‐dimensional mixing can serve as a new way to produce a filled type of PGM and is worthy of further investigation.

The prepared polyethylene/glass bead PGM; the graph illustrates the glass bead concentration gradient across the sample thickness.

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The prepared polyethylene/glass bead PGM; the graph illustrates the glass bead concentration gradient across the sample thickness.
An Analysis on Enhancement of Fatigue Durability of Polyurethane by Incorporating Organoclay Nanofillers
Authors: Jin Jie , Chen Lei , Song Mo , Yao Kejian
Published: November 2006

Summary: One of the important applications of PUEs is as damping materials such as the spring aids used in cars, which need to have excellent cyclic fatigue durability. Our results show that the fatigue durability of PUE can be significantly improved by incorporating organoclay. The best result was obtained for 3 wt.‐% organoclay, and the fatigue durability of the PUE‐organoclay nanocomposites was increased on an average to about ten times that of pure PUE. The addition of organoclay resulted in a reduction in the size of hard‐segment domains. The organoclay nanoplatelets show reversible deformation behaviour during a fatigue test confirmed by WAXD and computer simulation. These could benefit in stopping crack propagation, releasing concentrated stress and giving rise to fatigue resistance.

Schematic diagram of d‐spacing on nanoscale change during stretching.

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Schematic diagram of d‐spacing on nanoscale change during stretching.
Intercalation of Diphenyl Sulfide into Nanogalleries and Preparation of Poly(p‐phenylenesulfide)‐Based Nanocomposites
Authors: Saito Tomotaka , Okamoto Masami , Hiroi Ryoichi , Yamamoto Minoru , Shiroi Takashi
Published: November 2006

Summary: For the reference system of PPS‐based nanocomposites, we investigated the intercalation behavior of DFS molecules into nano galleries based on OMLFs consisting of different types of intercalants and nanofillers with different surface charge densities. The smaller initial interlayer opening led to the larger interlayer expansion, regardless of the miscibility between the intercalant and DFS. We examined the preparation of PPS‐based nanocomposites with and/or without shear processing at 300 °C. The finer dispersion of OMLFs in the nanocomposite was observed when using OMLF having small initial interlayer opening. The delamination of the stacked nanofillers was governed by the initial interlayer opening, whereas the uniform dispersion of the nanofillers was affected by the shear.

Plot of initial interlayer opening versus Δ opening for various OMLFs intercalated with DFS.

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Plot of initial interlayer opening versus Δ opening for various OMLFs intercalated with DFS.
Back Cover: Macromol. Mater. Eng. 11/2006
Authors: Saito Tomotaka , Okamoto Masami , Hiroi Ryoichi , Yamamoto Minoru , Shiroi Takashi
Published: November 2006

Back Cover: Despite the immiscibility between octadecylammonium (ODA) and diphenyl sulfide (DFS), the layer expansion in montmorillonite‐ODA takes place after mixing with DFS, indicating the DFS intercalation into nano‐galleries. Further details can be found in the article by T. Saito, M. Okamoto,* R. Hiroi, M. Yamamoto, and T. Shiroi on page 1367.
Nanofibrous Sugar Sticks Electrospun from Glycopolymers for Protein Separation via Molecular Recognition
Authors: Yang Qian , Wu Jian , Li Jun‐Jie , Hu Meng‐Xin , Xu Zhi‐Kang
Published: November 2006

Summary: Nanofibrous sugar sticks with linear PANCGAMA and cyclic PANCAG glucose pendants were fabricated by electrospinning from acrylonitrile‐based glycopolymers. Field emission scanning electron microscope was used to characterize the morphologies of the nanofibers. Utilizing the specific carbohydrate‐protein interaction, these two kinds of nanofiber mats were applied to separate the protein mixtures. Con A and BSA were used as model proteins. The Con A/BSA mixture solution was isolated successfully by selective adsorption of Con A to the cyclic glucose pendants on the PANCAG nanofibrous sugar sticks. However, PANCGAMA nanofibers showed almost no selectivity for these two proteins due to the poor specificity between linear glucose pendants and Con A.

Typical SEM images of nanofibers fabricated from PANCAG1.

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Typical SEM images of nanofibers fabricated from PANCAG1.
Synthesis and Characterization of Novel Glycerol‐Derived Polycarbonates with Pendant Hydroxyl Groups
Authors: Mei Hujie , Zhong Zhenlin , Long Feifu , Zhuo Renxi
Published: November 2006

Summary: A novel type of glycerol‐derived, water‐soluble polycarbonate with pendant, primary hydroxyl groups was prepared from 2‐(2‐benzyloxyethoxy)trimethylene carbonate (BETC). Ring‐opening polymerization of BETC and 2,2‐dimethyltrimethylene carbonate (DTC) gave narrow distribution of homopolymers or random copolymers with high molecular weights. The protecting benzyl groups were removed by catalyzed hydrogenation at atmosphere H2 pressure to give hydroxyl polycarbonates without observable changes on the polymer backbone and molecular weight distribution. The hydrophilicity of the copolymers increases with the increase in the hydrophilic glycerol‐derived carbonate content.

Synthesis of the glycerol‐derived polycarbonate.

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Synthesis of the glycerol‐derived polycarbonate.
New Approach to the Synthesis of Polyacrylamide in Miniemulsified Systems
Authors: Blagodatskikh Inesa , Tikhonov Vladimir , Ivanova Elena , Landfester Katharina , Khokhlov Alexei
Published: November 2006

Summary: A new approach to the preparation of water soluble polymer in inverse miniemulsions is proposed. A redox initiation system consisting of ceric ions and carbohydrate‐based surfactant Span 60 as a reducing agent is successfully used for the polymerization of AAm. This initiation system provides chain nucleation and growth near interfacial boundaries. As a result, stable uniform latex with particle radius of about 50–70 nm is obtained. The prepared PAAm has a rather high $\overline M _{\rm w}$ of up to about 2 × 106 Da.

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Autopsy‐proven Huntington's disease with 29 trinucleotide repeats
Authors: Kenney Christopher , Powell Suzanne , Jankovic Joseph
Published: November 2006

Huntington's disease (HD) is a neurodegenerative disorder associated with expansion of CAG trinucleotide repeats in the huntingtin gene. A minimum of 36 CAG repeats is usually reported in patients with clinical features of HD; 30 to 35 repeats represent an intermediate range. Here we report a 65‐year‐old male with autopsy‐proven HD and 29 CAG repeats. © 2006 Movement Disorder Society
Movement Disorder Society‐sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS‐UPDRS): Process, format, and clinimetric testing plan
Authors: Goetz Christopher G. , Fahn Stanley , Martinez‐Martin Pablo , Poewe Werner , Sampaio Cristina , Stebbins Glenn T. , Stern Matthew B. , Tilley Barbara C. , Dodel Richard , Dubois Bruno , Holloway Robert , Jankovic Joseph , Kulisevsky Jaime , Lang Anthony E. , Lees Andrew , Leurgans Sue , LeWitt Peter A. , Nyenhuis David , Olanow C. Warren , Rascol Olivier , Schrag Anette , Teresi Jeanne A. , Van Hilten Jacobus J. , LaPelle Nancy
Published: November 2006

This article presents the revision process, major innovations, and clinimetric testing program for the Movement Disorder Society (MDS)–sponsored revision of the Unified Parkinson's Disease Rating Scale (UPDRS), known as the MDS‐UPDRS. The UPDRS is the most widely used scale for the clinical study of Parkinson's disease (PD). The MDS previously organized a critique of the UPDRS, which cited many strengths, but recommended revision of the scale to accommodate new advances and to resolve problematic areas. An MDS‐UPDRS committee prepared the revision using the recommendations of the published critique of the scale. Subcommittees developed new material that was reviewed by the entire committee. A 1‐day face‐to‐face committee meeting was organized to resolve areas of debate and to arrive at a working draft ready for clinimetric testing. The MDS‐UPDRS retains the UPDRS structure of four parts with a total summed score, but the parts have been modified to provide a section that integrates nonmotor elements of PD: I, Nonmotor Experiences of Daily Living; II, Motor Experiences of Daily Living; III, Motor Examination; and IV, Motor Complications. All items have five response options with uniform anchors of 0 = normal, 1 = slight, 2 = mild, 3 = moderate, and 4 = severe. Several questions in Part I and all of Part II are written as a patient/caregiver questionnaire, so that the total rater time should remain approximately 30 minutes. Detailed instructions for testing and data acquisition accompany the MDS‐UPDRS in order to increase uniform usage. Multiple language editions are planned. A three‐part clinimetric program will provide testing of reliability, validity, and responsiveness to interventions. Although the MDS‐UPDRS will not be published until it has successfully passed clinimetric testing, explanation of the process, key changes, and clinimetric programs allow clinicians and researchers to understand and participate in the revision process. © 2006 Movement Disorder Society
Dilation‐free graphs in the l1 metric
Authors: Cáceres J. , Grima C.I. , Márquez A. , Moreno‐González A.
Published: November 2006

The dilation‐free graph of a planar point set S is a graph that spans S in such a way that the distance between two points in the graph is no longer than their planar distance. Metrically speaking, those graphs are equivalent to complete graphs; however they have far fewer edges when considering the Manhattan distance (we give here an upper bound on the number of saved edges). This article provides several theoretical, algorithmic, and complexity features of dilation‐free graphs in the l1‐metric, giving several construction algorithms and proving some of their properties. Moreover, special attention is paid to the planar case due to its applications in the design of printed circuit boards. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 49(2), 168–174 2007
Comparison of linear and classical velocity update rules in particle swarm optimization: notes on scale and frame invariance
Authors: Wilke Daniel N. , Kok Schalk , Groenwold Albert A.
Published: November 2006

In this paper we investigate whether the particle swarm optimization (PSO) algorithm is invariant of the scale and frame (i.e. translation and rotation) in which an objective function is posed. To do so, we study the linear and classical velocity update rules. We will show that thelinearvelocity update rule is scale and frameinvariant, but that theclassicalvelocity update rule lacksrotational invariance.

It is known that the linear velocity update rule lacks diversity, resulting in particle trajectories that collapse to line searches. In contrast, the classical velocity update rule maintains diverse (space filling) particle trajectories.

To illustrate that diversity and invariance are not necessarily exclusive, we propose a new velocity update rule. This update rule, which is just one example of many possible formulations, is rotationally invariant and at the same time directionally diverse. This is achieved through consistent perturbation of the search directions.

We quantify the (in)variance and performance of the three different implementations using a popular test set. The test problems are evaluated in both unrotated and arbitrarily rotated reference frames. Copyright © 2006 John Wiley & Sons, Ltd.
A Frobenius solution to the scaled boundary finite element equations in frequency domain for bounded media
Authors: Yang Z. J. , Deeks A. J. , Hao H.
Published: November 2006

The scaled boundary finite element method (FEM) is a recently developed semi‐analytical numerical approach combining advantages of the FEM and the boundary element method. Although for elastostatics, the governing homogeneous differential equations in the radial co‐ordinate can be solved analytically without much effort, an analytical solution to the non‐homogeneous differential equations in frequency domain for elastodynamics has so far only been obtained by a rather tedious series‐expansion procedure. This paper develops a much simpler procedure to obtain such an analytical solution by increasing the number of power series in the solution until the required accuracy is achieved. The procedure is applied to an extensive study of the steady‐state frequency response of a square plate subjected to harmonic excitation. Comparison of the results with those obtained using ABAQUS shows that the new method is as accurate as a detailed finite element model in calculating steady‐state responses for a wide range of frequencies using only a fraction of the degrees of freedom required in the latter. Copyright © 2006 John Wiley & Sons, Ltd.
On convergence of certain finite volume difference discretizations for 1D poroelasticity interface problems
Authors: Ewing Richard E. , Iliev Oleg P. , Lazarov Raytcho D. , Naumovich Anna
Published: November 2006

In the article two finite difference schemes for the 1D poroelasticity equations (Biot model) with discontinuous coefficients are derived, analyzed, and numerically tested. A recent discretization [Gaspar et al., Appl Numer Math 44 (2003), 487–506] of these equations with constant coefficients on a staggered grid is used as a basis. Special attention is given to the interfaces and as a result a scheme with harmonic averaging of the coefficients is derived. Convergence rate of O(h3/2) in a discrete H1‐norm for both the pressure and the displacement is established in the case of an arbitrary position of the interface. Further, rate of O(h2) is proven for the case when the interface coincides with a grid node. Following an approach applied to second‐order elliptic equations in [Ewing et al., SIAM J Sci Comp 23(4) (2001), 1334–1350] we derive a modified and more accurate discretization that gives second‐order convergence of the fluid velocity and the stress of the solid. Finally, numerical experiments of model problems that confirm the theoretical considerations are presented. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2007
Unified approach for open‐loop optimal control
Authors: Imura Y. , Naidu D. S.
Published: November 2006

We develop a unified approach for the necessary conditions for optimization ofopen‐loopcontrol systems, starting from the basic principles of calculus of variations. The unified approach results are simultaneously applicable to both shift (q)‐operator‐based, discrete‐time systems and the derivative (d/dt)‐operator‐based, continuous‐time systems. It is shown that the optimal condition results that are now obtained separately for continuous‐time and discrete‐time systems can be easily obtained from the unified approach. An illustrative example is given. Copyright © 2006 John Wiley & Sons, Ltd.
Selective binding of nanoparticles on surfaces and into polymeric matrices via directed hydrogen bonding interactions
Authors: Binder Wolfgang H. , Zirbs Ronald , Kienberger Ferry , Hinterdorfer Peter
Published: November 2006

The attachment of nanoparticles (NPs) onto planar surfaces and into specific phases of block copolymers is an important prerequisite for exerting their function on/in matrices for application in the field of nanotechnology. Besides non‐directional binding modes (i.e. interfacial ordering effects) most known methods rely on intermolecular ordering forces to mediate binding of NPs onto surfaces. The approach towards NP‐binding onto surfaces relies on directed, multiple hydrogen bonding systems. In this study the modular generation of surfaces and bulk‐phases with hydrogen bonding receptors and the stable binding of the NPs onto the derivatized surfaces by atomic force microscopy (AFM) are reported. To this respect surfaces presenting Hamilton‐type receptors (displaying association constants > 3 × 104 M−1) using Sharpless‐1,3‐dipolar cycloaddition reactions are prepared in high efficiency. Nanoparticle binding is studied with Au‐NPs surface modified with barbituric acid‐receptors. Binding of the particles to a surface presenting 100 mol% of receptor shows a highly dense packed layer of Au‐NPs on the surface as seen by AFM measurements. The density of the receptors is the important factor in controlling a selective binding process, achieving > 100 fold binding selectivity. The present approach opens an efficient and general mode to direct nanoparticle assembly onto nanoscaled surfaces. Copyright © 2006 John Wiley & Sons, Ltd.
Rapid response of a poly(acrylamide) hydrogel having a semi‐interpenetrating polymer network structure
Authors: Miyata Takashi , Asami Noriko , Okawa Kaori , Uragami Tadashi
Published: November 2006

Responsiveness of a poly(acrylamide) (PAAm) hydrogel having a semi‐interpenetrating polymer network (semi‐IPN) structure was compared with that of a PAAm normal‐type hydrogel in acetone/water mixtures. The PAAm semi‐IPN hydrogel shrank much more rapidly by changes in the acetone concentration than the PAAm normal‐type hydrogel though there was no difference in their equilibrium swelling ratio between them. This suggests that the introduction of a semi‐IPN structure into a hydrogel enhances its responsiveness very easily. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and properties of new phosphorus‐containing poly(ester‐imide)s
Authors: Vlad‐Bubulac Tachita , Hamciuc Corneliu , Petreus Oana , Bruma Maria
Published: November 2006

New phosphorous‐containing poly(ester‐imide)s have been prepared by polycondensation in solution at high temperature of a p‐hydroxyphenol containing phosphorus, namely 2‐(6‐oxid‐6H‐dibenz<1,2>oxaphosphorin‐6‐yl)‐1,4‐benzenediol, with various aromatic diacide chlorides containing preformed imide rings. The polymers were easily soluble in polar organic solvents, such as N‐methylpyrrolidone, N,N‐dimethylformamide, tetrahydrofuran and chloroform. They showed high thermal stability, the decomposition temperature being above 360°C and the glass transition in the temperature range 142–223°C. One of these polymers exhibited thermotropic liquid crystalline behavior. Solutions of the phosphorous‐containing poly(ester‐imide)s in N,N‐dimethylformamide showed fluorescence having a maximum emission wavelength in the range 376–378 nm. Due to the presence of phosphorus the polymers gave high char yield in thermogravimetric analysis. Copyright © 2006 John Wiley & Sons, Ltd.
Semi‐continuous emulsion copolymerization of vinyl acetate and butyl acrylate using a new protective colloid. Part 2. Effects of monomer ratio and initiator
Authors: Sarac Ayfer , Berber Hale , Yildirim Hüseyin
Published: November 2006

Poly(vinyl acetate‐co‐butyl acrylate) latexes with N‐methylol acrylamide were prepared by semi‐continuous emulsion polymerization. The influence of the different initiators and various monomer ratios was studied to relate its physicochemical and colloidal properties. The changes in the copolymer latexes with the use of ammonium persulfate and potassium persulfate initiators were investigated by monitoring viscosity, molecular weights, molecular weight distribution and particle size. It was found that almost all physicochemical and colloidal properties of the latexes followed the same trends for both initiators. Potassium persulfate gave slightly higher results for number‐ and weight‐average molecular weights than ammonium persulfate. Copyright © 2006 John Wiley & Sons, Ltd.
Structural and performance variation of activated carbon‐polymer films
Authors: Ballinas‐Casarrubias L. , Terrazas‐Bandala L. P. , Ibarra‐Gómez R. , Mendoza‐Duarte M. E. , Manjarrez‐Nevárez L. , González‐Sánchez G.
Published: November 2006

Activated carbon particles were obtained by a solvatation method and added as fillers in cellulose triacetate as polymeric matrix. Various composite films were prepared by solvent casting at different controlled temperature and relative humidity (35–55° C, 10–70% RH) conditions, for three different filler loadings (0, 1 and 3%). Scanning electron microscopy (SEM) images revealed that for slow solvent evaporation rates (low temperature and high RH) a non‐agglomerated composite film is achieved. This condition observed in SEM was correlated to the film with the best mechanical properties found by stress‐strain and creep tests. Water flux and mechanical resistance is also higher for the membrane obtained at the best synthesis conditions found (M1) (35°C, 70% RH). Contact angle measurements indicated that there is differentiation among membranes of different carbon loading respect to M1, associated to surface homogeneity. Atomic force microscopy (AFM) images showed structural variation among membranes (M1 and its counterpart without carbon) in the nanoscale. Contrast phase AFM analysis exposed homogeneous dispersion of activated carbon particles on membrane M1. Major adhesion between entangled polymer network and activated carbon is postulated as the main factor for the composite polymer proper structural performance. Copyright © 2006 John Wiley & Sons, Ltd.
Identification of responders and reactive domains to rivastigmine in Alzheimer's disease
Authors: Frankfort S. V. , Appels B. A. , de Boer A. , Tulner L. R. , van Campen J. P. C. M. , Koks C. H. W. , Beijnen J. H. , Schmand B. A.
Published: November 2006

Purpose

Presently, it is unclear which patients suffering from Alzheimer's Disease (AD) respond to rivastigmine and if rivastigmine acts on specific cognitive domains. The aims of this study are thus to investigate treatment effects of rivastigmine on specific cognitive domains and to find possible responsive subpopulations to rivastigmine cognitive effects.

Methods

Mini Mental State Examination (MMSE) and Cambridge Cognitive Examination (CAMCOG) were administered at baseline and after 6 months in 83 rivastigmine users and 96 historical controls, representing natural decline. Treatment effects on different subsections of the CAMCOG and in different subpopulations were investigated by linear regression analyses.

Results

Rivastigmine showed effectiveness on total CAMCOG (p < 0.001), CAMCOG non‐memory subsection (p < 0.001) and subscales of language (p = 0.002), attention/calculation (p = 0.043), abstract thinking (p < 0.001) and perception (p = 0.031). In patients with baseline MMSE ≤19 rivastigmine showed significant and favourable effects compared to historical controls on total CAMCOG (p < 0.001) and both non‐memory (p < 0.001) and memory subsections (p = 0.002).

Conclusion

Rivastigmine showed primarily effectiveness on the non‐memory section of the CAMCOG and patients with a baseline MMSE ≤ 19 appeared to show greater responses to rivastigmine compared to patients with baseline MMSE ≥ 20. Copyright © 2006 John Wiley & Sons, Ltd.
Brownian dynamics simulation of polyelectrolyte dilute solutions under shear flow
Authors: Pamies R. , Cifre J.G. Hernández , De La Torre J. García
Published: November 2006

The behavior of dilute solutions of linear polyelectrolyte molecules both at equilibrium and under shear flow is modeled by using the Brownian dynamics simulation technique. The mathematical polymer model consists of a bead‐and‐spring chain with charged beads that interact through a screened Debye–Hückel potential as well as through FENE spring forces. In addition hydrodynamic interaction is included in the simulations. We also illustrate how to parameterize a real polyelectrolyte chain, using as an example the often studied sodium polystyrene sulfonate. This gives us an estimate of the values of the model parameters to be used in the simulations. The dependence of conformational and hydrodynamic properties on salt concentration (parameterized through the Debye length) and on electrostatic strength (related to the degree of ionization) is studied. It is found that the model describes many of the features of polyelectrolyte dilute solutions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1–9, 2007
What to do when ‘there is nothing more to do’? A study within a salutogenic framework of family members' experience of palliative home care staff
Authors: Milberg A. , Strang P.
Published: November 2006

The aim of this study was to develop a theoretical framework of family members' experience of palliative home care staff based on a secondary analysis of four previous studies. A salutogenic framework was used, i.e. with the origin of health in focus. Data had been collected (semi‐structured tape‐recorded interviews and postal questionnaires with open‐ended questions) from 469 family members of mainly cancer patients referred to advanced palliative home care. Walker and Avant's strategies for theory construction were used. The secondary analysis generated three theoretical blocks: (1) general components of staff input (including five generalized resistance resources (GRRs): competence, support, spectrum of services, continuity, and accessibility); (2) specific interactions with staff (including two GRRs: being in the centre and sharing caring); (3) emotional and existential consequences of staff support (including six health‐disease continuums: security‐insecurity, hope–hopelessness, congruent inner reality‐chaos, togetherness‐isolation, self‐transcendence‐feelings of insufficiency and retained everyday life‐disrupted everyday life). It seems important that all three aspects of family members' experience of palliative care staff are to be considered in evaluations of palliative care, in goal‐setting and in teaching role models. The study is specific to the Swedish model of palliative home care and replication of the work in other countries is recommended. Copyright © 2006 John Wiley & Sons, Ltd.
Disease severity, mental health, and quality of life of children and adolescents with asthma
Authors: Goldbeck Lutz , Koffmane Katja , Lecheler Josef , Thiessen Kai , Fegert Jörg M.
Published: November 2006

Asthma has been found related to a higher risk of psychological problems. Inconsistent results have been reported with respect to the quality of life of children with asthma. So there may be a complex relationship between asthma severity, quality of life, and psychological factors. The aim of this study was to examine the impact of asthma severity and emotional/behavioral problems on the quality of life of children and adolescents and on their need for support.Eighty‐one children and adolescents (7–18 years old, 62 boys, 19 girls) with asthma participating in different intervention and rehabilitation programs completed the Ulm Inventory for Children, an instrument for assessing health‐related quality of life. Psychological problems were rated using the Child Behavior Checklist (CBCL). Caregivers judged the patients' need for support due to asthma and due to psychosocial problems. Asthma severity was rated according to the GINA classification.The participants showed elevated caregiver‐reported emotional and behavioral symptoms compared with the normative sample (mean CBCL total score T = 63). Quality of life and the need for social support were significantly correlated with psychological symptoms. Asthma severity was neither correlated with quality of life nor with emotional/behavioral symptoms, but it was associated with the need for support due to asthma.Therefore, in our study, comorbid emotional and behavioral symptoms rather than disease severity predicted quality of life of children and adolescents with asthma. Treatment should be adjusted to the special needs of children with asthma and comorbid mental health problems. Pediatr Pulmonol. 2007; 42:15–22. © 2006 Wiley‐Liss, Inc.
Learning about protein hydrogen bonding by minimizing contrastive divergence
Authors: Podtelezhnikov Alexei A. , Ghahramani Zoubin , Wild David L.
Published: November 2006

Defining the strength and geometry of hydrogen bonds in protein structures has been a challenging task since early days of structural biology. In this article, we apply a novel statistical machine learning technique, known as contrastive divergence, to efficiently estimate both the hydrogen bond strength and the geometric characteristics of strong interpeptide backbone hydrogen bonds, from a dataset of structures representing a variety of different protein folds. Despite the simplifying assumptions of the interatomic energy terms used, we determine the strength of these hydrogen bonds to be between 1.1 and 1.5 kcal/mol, in good agreement with earlier experimental estimates. The geometry of these strong backbone hydrogen bonds features an almost linear arrangement of all four atoms involved in hydrogen bond formation. We estimate that about a quarter of all hydrogen bond donors and acceptors participate in these strong interpeptide hydrogen bonds. Proteins 2007. © 2006 Wiley‐Liss, Inc.
Enhanced degradation of atrazine under field conditions correlates with a loss of weed control in the glasshouse
Authors: Krutz L Jason , Zablotowicz Robert M , Reddy Krishna N , Koger III Clifford H , Weaver Mark A
Published: November 2006

Enhanced degradation of atrazine has been reported in the literature, indicating the potential for reduced residual weed control with this herbicide. Experiments were conducted to determine the field dissipation of atrazine in three cropping systems: continuous Zea mays L. (CC) receiving atrazine applications each year, Gossypium hirsutum L.–Z. mays rotation (CCR) receiving applications of atrazine once every 2 years and a no atrazine history soil (NAH). Subsequent laboratory and greenhouse experiments were conducted with soil collected from these cropping systems to determine atrazine degradation, mineralization and residual weed control. Field dissipation of atrazine followed first‐order kinetics, and calculated half‐life values for atrazine combined over 2003 and 2005 increased in the order of CC (9 d) = CCR (10 d) < NAH (17 d). Greenhouse studies confirmed that the persistence of atrazine was approximately twofold greater in NAH soil than in CC or CCR soil. Biometer flask mineralization studies suggested that enhanced degradation of atrazine was due to rapid catabolism of the s‐triazine ring. Glasshouse efficacy studies revealed a loss of residual weed control in CC and CCR soil compared with NAH soil. These data indicate that, under typical Mississippi Delta field conditions and agronomic practices, the persistence of atrazine may be reduced by at least 50% if the herbicide is applied more than once every 24 months. Glasshouse studies suggest that under these conditions a loss of residual weed control is possible. Published in 2006 by John Wiley & Sons, Ltd
ESR study of La1–xPbxMnO3 (0.1 ≤ x ≤ 0.5) perovskites
Authors: Phan T. L. , Min S. G. , Phan M. H. , Ha N. D. , Chau N. , Yu S. C.
Published: November 2006

Electron spin resonance (ESR) spectra of La1–x Pbx MnO3 (0.1 ≤ x ≤ 0.5) compounds were recorded at different temperatures. Asymmetrical and distored resonance signals due to ferromagnetic correlations at temperatures T < Tmin became Lorentzian at T > Tmin, where Tmin is the temperature corresponding to the narrowest ESR linewidth. The ESR linewidth with respect to temperature, ΔH (T), for the samples was fitted to the one‐phonon process, ΔH (T) = A + BT. We found that B decreased from 5.45 Oe/K for x = 0.1 to 4.61 Oe/K for x = 0.5, indicating the decrease of lattice distortions with the Pb addition. The tem‐ perature dependence of the ESR intensity, I (T), for the samples was described well to an expression of I (T) = I0 exp (Ea/kBT). In the high‐temperature region, 1/I (T) obeyed the Curie–Weiss law. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Natural products as alternative treatments for metabolic bone disorders and for maintenance of bone health
Authors: Putnam Sophie E. , Scutt Andy M. , Bicknell Katrina , Priestley Caroline M. , Williamson Elizabeth M.
Published: November 2006

Bone metabolism involves a complex balance between the deposition of matrix and mineralization and resorption. There is now good evidence that dietary components and herbal products can influence these processes, particularly by inhibiting bone resorption, thus having beneficial effects on the skeleton. For example, it has been reported that a number of common vegetables, including onion, garlic and parsley, can inhibit bone resorption in ovariectomized rats. Essential oils derived from sage, rosemary, thyme and other herbs inhibit osteoclast activity in vitro and in vitro and leading to an increase in bone mineral density. Soya, a rich source of isoflavones, has shown promising results and epidemiological evidence to support a use in maintaining bone health, and various traditional herbal formulae in Chinese and Ayurvedic medicine also have demonstrable effects in pharmacological models of osteoporosis. Recently, cannabinoids have been described as having positive effects on osteoblast differentiation, and the presence of cannabinoid receptors in bone tissue indicates a more complex role in bone metabolism than previously thought. The first part of this review briefly discusses normal bone metabolism and disorders caused by its disruption, with particular reference to osteoporosis and current pharmacological treatments. The effects of natural products on bone and connective tissue are then discussed, to include items of diet, herbal extracts and food supplements, with evidence for their efficacy outlined. Copyright © 2006 John Wiley & Sons, Ltd.
Similarity Metrics and Descriptor Spaces – Which Combinations to Choose?
Authors: Glen Robert C. , Adams Samuel E.
Published: November 2006

Molecular similarity is widely used in virtual screening. There are a very large number of possible combinations of molecular descriptors and analysis methods that can be combined to pre‐select compounds. The objectives strongly influence the methods chosen, in particular whether the desired outcome is to design a diverse library for initial screening; to follow up with additional similar hits (to perhaps help in establishing SAR) or to discover novel scaffolds (lead hopping) with the objective of obtaining novel patentable series (perhaps with different pharmacokinetics). Some of the factors that influence these decisions are discussed along with applications that compare and contrast methods and their performance in different situations.
Time‐Series QSAR Analysis of Human Plasma Protein Binding Data
Authors: Rodgers Sarah L. , Davis Andrew M. , van de Waterbeemd Han
Published: November 2006

Quantitative Structure–Activity Relationship (QSAR) models are built using a wide variety of methods and descriptors in order to produce the optimal model for a given property or activity. Once built, models tend to be static or very rarely updated, yet chemistry progresses with time. Any QSAR model is limited by the data used to create it, which in turn is dependent on the data available at the time of building. This study investigates the time dependence of the predictive ability of QSAR models. This is achieved by examining the performance of a human plasma protein binding model over time. A number of QSAR models were built using Partial Least‐Squares (PLS) and tested using data collected from experiments conducted at specific time points over a two‐year period. The ability of these updated models to make predictions was compared with that of a model built with data from the beginning of the time period. In general, the updated models are stable over time and predictions vary only to a small degree from one model to the next. However, for both current and future test data, the updated models are overall more effective at making predictions than the static model. This highlights the benefits of using more current data for making predictions and thus the need for autoupdating QSAR models.
Ab initio study on the reaction mechanism of ozone with bromine atom
Authors: Bing Dan , Zhao Yongfang , Hao Fengyou , Li Xinying , Liu Fengli , Zhang Guohua , Zhang Pingxia
Published: November 2006

Ab initio calculations of the potential energy surface (PES) for the Br+O3 reaction have been performed using the MP2, CCSD(T), and QCISD(T) methods with 6‐31G(d), 6‐311G(d), and 6‐311+G(3df). The reaction begins with a transition state (TS) when the Br atom attacks a terminal oxygen of ozone, producing an intermediate, the bromine trioxide (M), which immediately dissociates to BrO+O2. The geometry optimizations of the reactants, products, and intermediate and transition states are carried out at the MP2/6‐31G(d) level. The reaction potential barrier is 3.09 kcal/mol at the CCSD(T)/6‐311+G(3df)//MP2 level, which shows that the bromine atom trends intensively to react with the ozone. The comparison of the Br+O3 reaction with the F+O3 and Cl+O3 reactions indicates that the reactions of ozone with the halogen atoms have the similar reaction mechanism. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Conformational analysis for some nonclassical antagonists of histamine H3 receptor
Authors: Borota Ana , Mracec Maria , Rad Ramona , Ostopovici Liliana , Mracec Mircea
Published: November 2006

A conformational search in vacuum for a series of 1,3‐substituted pyrrolidine derivatives has been performed using the AMBER, AM1, PM3, and MNDO methods. Conformational analysis of the pyrrolidine ligands suggests that these compounds could have many conformers that populate the low‐energy minima on the potential energy surface (PES). The conformational space occupied by the ligands is large and, in vacuum, the rotation barriers of different flexible bonds have energies between 0.5 and thousands of kcal/mol. By optimization, most conformers have energy barriers of 0–5 kcal/mol; thus, they could interconvert easily to obtain better interactions in the receptor active site. Optimized conformers having energy barriers of >5 kcal/mol display bad geometries with very large bond lengths and deformed rings. Shapes and heights of rotation barriers obtained through COSMO–AM1 single‐point calculations in water are similar to those obtained from single‐point calculations in vacuum. However, in water the energy barriers are lower, allowing most conformers to convert in other low‐energy conformers. The best conformers in vacuum and in water are different: the gas phase best conformer has a helical shape, while the best conformer in water has an extended shape. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Minimum proton affinity for efficient ionization with atmospheric pressure desorption/ionization on silicon mass spectrometry
Authors: Östman Pekka , Pakarinen Jaana M. H. , Vainiotalo Pirjo , Franssila Sami , Kostiainen Risto , Kotiaho Tapio
Published: November 2006

We performed a systematic study using a set of compounds with different proton affinities (PAs) on the ionization in atmospheric pressure desorption/ionization on silicon mass spectrometry (AP‐DIOS‐MS). The compounds studied included various aromatic molecules of different sizes. The PAs of these compounds were calculated using ab initio and hybrid density functional theory calculations at the B3LYP/6‐31G(d) level of theory. We observed that only compounds with relatively high PAs above a threshold value of 920–950 kJ/mol were efficiently ionized as protonated molecules under AP‐DIOS conditions and produced very clean mass spectra. Copyright © 2006 John Wiley & Sons, Ltd.
A model for assembly program maintenance
Authors: Chen S. , Heisler K. G. , Tsai W. T. , Chen X. , Leung E.
Published: November 2006

This paper presents a model for understanding assembly programs for software maintenance. It is based on the theory that explicit representation of various structural and functional elements of code and multiple relationships among them will aid program understanding and thus software maintenance. We present a parsing technique to extract all the required elements from assembly code to populate the model. The model is a reverse engineering technique. We use the term reverse engineering in its broad sense to include specification as well as design recovery. Most features of this model have been implemented in a tool named “RETA” for Reverse Engineering Tool for Assembly programs.

The model is useful for software maintenance activities such as program understanding, ripple effect analysis, and program re‐documentation. The ripple effect of a contemplated change is the parts of code that depend on the variable or a piece of code to be changed. Once the change is made, those parts need to be re‐examined for possible modification. The model generates a functional menu for a given application. The menu describes the functionality of each routine. It is a hierarchical presentation of major program routines, the sub‐routines supporting each major routine and so on. A routine at any level of detail consists of one or more paths through the code. Paths are presented as control flow sequences between code blocks. Code blocks, and hence functionalities, use and modify data.

The maintainer locates the routine to be modified at the lowest level of detail within the functional menu. This automatically slices out the set of paths, and hence the set of code blocks, that have a role in the functionality to be changed. The code blocks in the slice determine the data that are used and modified within the routine to be changed. Path analysis and associated data‐used and data‐modified information are used to determine which code blocks are to be changed and which data roles are to be modified. The same set of relations are applied in reverse to identify the ripple effect.
Modelling and maintenance software systems at the teleological level
Authors: Karakostas V.
Published: November 2006

Software maintenance is necessitated to a large extent by changing user requirements. However, the relationship between the user requirements and the implemented software system is not made explicit in current development approaches, making the mapping of changing requirements to corresponding maintenance activities difficult. The teleological approach advocates the construction of a model which links the components of a software system to the concepts of the application domain which they implement, i.e to user requirements. Subsequently, the teleological model is used for simulating the actual maintenance activities, as they are triggered by the changing requirements, and for identifying their nature and estimating their cost.
Producing better maintainable JSD specifications by grouping common aspects
Authors: Borgers M. , Munro M.
Published: November 2006

The Jackson methodology for systems development is seen as a formal methodology. Although it is formal, the analyst has a freedom to specify models of problems in alternative ways without giving any indication which one is the better. Proposals to extend the methodology with the concepts ‘(near) static entity’ and ‘static roles’ give the analyst even more freedom than before. From the maintenance point of view this can lead to problems of understandability of the models. Also some enhancements cannot be done without completely redesigning entities. In this paper we propose to separate the existence aspect of an entity in one process. A second proposal is to model relationships (i.e. aspects comon to two or more entities) between entities explicitly using entity‐relationship notation. In this way, more maintainable specifications will be obtained.
Enhancements through design transformations: A retroactive case study
Authors: Rotenstreich Shmuel
Published: November 2006

A formal approach to software design in the form of transformations is shown to be useful for the redesign of existing systems. A design transformation maps a given design into an alternative design. Transformations are based on a model that consists of program blocks and the input and output data of these blocks. The result of a transformation may be a rearrangement of the blocks, splitting of blocks or a combination of existing blocks. Typically, software design concepts are applicable to designs that stem from specifications, they are less capable when applied to existing systems. A transformational scheme is inherently iterative. The redesign of existing systems is, therefore, the application of transformations starting from an iteration that happens to be the existing system. A real‐life example, in which a function in a distributed system was first designed and then redesigned, both intuitively, is the basis of the case study. We show that the redesign process that was undertaken in order to enhance a function can be achieved with the design transformations proposed. Through the example, we demonstrate that the transformational scheme is not difficult to apply, precise, and capable of reusing program components not affected by the redesign.
Insights into testing and regression testing global variables
Authors: Leung Hareton K. N. , White Lee
Published: November 2006

Despite the existence of global variables in many software systems, testing global variables has traditionally been overlooked by the testing community. This state of the practice leads to the release of some software systems with untested properties. In this paper, we present some insights into the problem of testing and regression testing global variables. A basis set of testing problems for parameters will be identified and the testing problem of global variables will be mapped onto a combination of these basis cases. It will be shown that global variables can be treated as parameters and can be tested accordingly. Testing strategies and regression testing strategies for unit, integration, and system testing global variables are described.