bluuebunny/crossref_metadata_2025 huggingface dataset:
Superparamagnetic iron oxide MION as a contrast agent for sodium MRI in myocardial infarction
Authors: Constantinides Chris D. , Rogers J. , Herzka D.A. , Boada F.E. , Bolar D. , Kraitchman D. , Gillen J. , Bottomley P.A.
Published: August 2002

An intravascular iron‐based contrast agent was used as a sodium (23Na) MRI T2 relaxant in an effort to suppress the blood signal from the ventricular cavities in normal and infarcted canine myocardium in vivo. 23Na MRI signal decreases in blood were attributed to decreases in the fast (T2f) and slow (T2s) transverse relaxation components, which were quantified as a function of dose and MRI echo time (TE). In vivo 23Na MRI signal decreases up to 65% were noted in ventricular blood when imaging under dose and TE conditions of 10 mg/kg body weight and 5 ms, respectively. Contrast injection followed by subsequent 23Na MRI in canine myocardial infarction led to a clear delineation of the location of the injured tissue, as identified by postmortem triphenyltetrazolium chloride staining, and to an improvement in the contrast‐to‐noise ratio between the blood in the ventricular chamber and the infarcted tissue that was as high as 3.3‐fold in the postcontrast images in comparison to the precontrast images. Magn Reson Med 46:1164–1168, 2001. © 2001 Wiley‐Liss, Inc.
Receptors for NGF and GDNF are highly expressed in human peripheral nerve neuroma
Authors: Harpf Christoph , Dabernig Jörg , Humpel Christian
Published: August 2002

Immunhistochemistry of 10 traumatic human peripheral nerve neuromas and 5 normal digital nerves revealed a high immunoreactivity for the nerve growth factor (NGF) receptors p75 and trkA and the glial cell line–derived neurotrophic factor (GDNF) receptor GFRα‐1. Semiquantitative image analysis showed a significantly increased trkA immunoreactivity in the neuroma group. The presence of the receptors may provide a way to influence therapy of peripheral nerve neuroma by administration of neurotrophins or other substances with binding sites similar to those of a neurotrophic factor. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Temporal effects of inactivty on myosin heavy chain gene expression in rat slow muscle
Authors: Huey Kimberly A. , Roy Roland R. , Baldwin Kenneth M. , Edgerton V. Reggie
Published: August 2002

Myosin heavy chain (MHC) mRNA and protein profiles in adult rat soleus and adductor longus were determined after 4, 8, 15, 30, 60, and 90 days of spinal cord isolation (SI). SI results in complete neuromuscular inactivity while leaving the motoneuron–muscle fiber connections intact. From 15 to 90 days, type I MHC mRNA was significantly decreased, whereas type I MHC protein did not significantly decrease until 30 and 60 days in the soleus and adductor longus, respectively. However, in both muscles, slow MHC downregulation was offset by significant upregulation of the faster MHC isoforms, primarily IIx. From 60 to 90 days, type I MHC was almost completely replaced with faster isoforms at the mRNA and protein levels. Thus, chronic inactivity and unloading of slow rat hindlimb muscles shifted the MHC profile from predominately type I to type IIx MHC mRNA and protein. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 517–526, 2001
Modulation of H reflex of pretibial and soleus muscles during mastication in humans
Authors: Takahashi Toshiyuki , Ueno Toshiaki , Taniguchi Hisashi , Ohyama Takashi , Nakamura Yoshio
Published: August 2002

A previous study in our laboratory demonstrated that the soleus H reflex was facilitated during mastication in humans. In the present study, we investigated whether there was any modulation of the magnitude of the pretibial H reflex during mastication in five healthy adult volunteers. The pretibial H reflex was significantly facilitated during mastication, and there was no significant difference in the facilitation between jaw‐closing and jaw‐opening phases; that is, the gain of the H reflex was modulated tonically but not in a phase‐dependent manner during mastication. Furthermore, in the same subjects, we confirmed that the soleus H reflex was facilitated during mastication. Based on our findings, we conclude that the H reflexes in both the pretibial and soleus muscles undergo a nonreciprocal facilitation during mastication. It is suggested that mastication contributes to stabilization of postural stance in humans. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1142–1148, 2001
Inventory control under substitutable demand: A stochastic game application
Authors: Avsar Zeynep Müge , Baykal‐Gürsoy Melike
Published: August 2002

Substitutable product inventory problem is analyzed using the concepts of stochastic game theory. It is assumed that there are two substitutable products that are sold by different retailers and the demand for each product is random. Game theoretic nature of this problem is the result of substitution between products. Since retailers compete for the substitutable demand, ordering decision of each retailer depends on the ordering decision of the other retailer. Under the discounted payoff criterion, this problem is formulated as a two‐person nonzero‐sum stochastic game. In the case of linear ordering cost, it is shown that there exists a Nash equilibrium characterized by a pair of stationary base stock strategies for the infinite horizon problem. This is the unique Nash equilibrium within the class of stationary base stock strategies. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 359–375, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10018
Peripheral somatosensory fMRI in mouse at 11.7 T
Authors: Ahrens Eric T. , Dubowitz David J.
Published: August 2002

The feasibility of performing extremely‐high resolution somatosensory fMRI in anesthetized mice using BOLD contrast at 11.7 T was investigated. A somatosensory stimulus was applied to the hindlimb of an α‐chlorolose anesthetized mouse resulting in robust (p < 4 × 10−3) BOLD changes in somatosensory cortex and large veins. Percentage modulation of the MR signal in cortex exceeded 7%. Experiments that artificially modulated the inspired oxygen tension were also conducted; the results revealed large, heterogeneous, BOLD contrast changes in the mouse brain. In addition, T1, T2, and T2* values in gray matter at 11.7 T were evaluated. Discussion of the sensitivity limitations of BOLD fMRI in the tiny mouse central nervous system is presented. These methods show promise for the assessment of neurological function in mouse models of CNS injury and disease. Copyright © 2001 John Wiley & Sons, Ltd.
Blended kernel approximation in the ℋ︁‐matrix techniques
Authors: Hackbusch W. , Khoromskij B. N.
Published: August 2002

Several types of ℋ︁‐matrices were shown to provide a data‐sparse approximation of non‐local (integral) operators in FEM and BEM applications. The general construction is applied to the operators with asymptotically smooth kernel function provided that the Galerkin ansatz space has a hierarchical structure.

The new class of ℋ︁‐matrices is based on the so‐called blended FE and polynomial approximations of the kernel function and leads to matrix blocks with a tensor‐product of block‐Toeplitz (block‐circulant) and rank‐k matrices. This requires the translation (rotation) invariance of the kernel combined with the corresponding tensor‐product grids. The approach allows for the fast evaluation of volume/boundary integral operators with possibly non‐smooth kernels defined on canonical domains/manifolds in the FEM/BEM applications. (Here and in the following, we call domains canonical if they are obtained by translation or rotation of one of their parts, e.g. parallelepiped, cylinder, sphere, etc.) In particular, we provide the error and complexity analysis for blended expansions to the Helmholtz kernel. Copyright © 2002 John Wiley & Sons, Ltd.
Finite element analysis for optimal design of foundations due to dynamic loading
Authors: Valliappan S. , Hakam A.
Published: August 2002

This paper discusses the optimal design of foundations subjected to dynamic loading, using the finite element method to determine the responses of the system. A three‐dimensional finite element programme for dynamic analysis in time domain has been developed using Newmark's integration scheme for the discretization in time domain. In order to consider the infinite extent of the foundation domain, unified boundary condition has been adopted. Only linear material behaviour is included at present. The design variables are the dimensions of the foundation while the constraints are amplitudes, acceleration, velocities and frequencies of the system. The results of the numerical examples show that the foundations subjected to dynamic loading can be designed both economically and effectively using the proposed method. Copyright © 2001 John Wiley & Sons, Ltd.
Constitutive relation errors for F.E. analysis considering (visco‐) plasticity and damage
Authors: Ladevèze Pierre
Published: August 2002

A posteriori error estimators based on constitutive relation residuals are developed to measure the quality of finite element computations of structures which exhibit plastic/viscoplastic behaviour with softening. All the classical error sources involved in the computation over the studied time interval are taken into account: the space discretization (the mesh), the time discretization and the iterative technique used to solve the non‐linear discrete problem. Copyright © 2001 John Wiley & Sons, Ltd.
Fourth‐order approximation for the three space dimensional certain mildly quasi‐linear hyperbolic equation
Authors: Mohanty R. K. , Arora Urvashi , Jain M. K.
Published: August 2002

In 1995, Mohanty et al. [1] proposed a fourth‐order finite difference scheme for the numerical solution of a three space dimensional singular hyperbolic equation and discussed an operator splitting method for a linear equation having first‐order space derivative terms. In this article, we extend our strategy for the difference solution of a three space dimensional quasi‐linear hyperbolic equation. Fourth‐order approximation at the first‐time level for a more general case is also proposed. Linear stability analysis and an operator splitting technique for a linear hyperbolic equation having a first‐order time derivative term are discussed. Numerical results are given to illustrate the accuracy of the proposed methods. © 2001 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 17: 277–289, 2001
The role of nonprofit associations in combating social exclusion in France
Authors: Warin Philippe
Published: August 2002

Associations are increasingly participating in matters concerning social policies in France. The fight against the problems of social exclusion and the development of a social urgency field offer many opportunities for partnerships between the associative/nonprofit and public actors. Associations are invited to implement policies, with or sometimes instead of government administrations. At the same time, many strong associative networks intervene directly as experts supporting the ministerial cabinets that coordinate policy formulation. From this point of view, individual and contractual relations play an important role. Today, all the main social reforms in France are, in large part, founded on analyses and ideas provided by associative actors. Beyond the reinforcement of associations, and despite the fact they are simultaneously partners and interest groups, different associative leaders are working with some administrative and political actors to develop a new foundation for joint action between the government and nonprofit sectors. Under the guise of recent laws which normalize the position of the associations, this coalition is seeking to transform the national public accountancy in order to acknowledge the activities and riches produced by the nonprofit sector. Copyright © 2002 John Wiley & Sons, Ltd.
Fractal dimension of trabecular bone: comparison of three histomorphometric computed techniques for measuring the architectural two‐dimensional complexity
Authors: Chappard Daniel , Legrand Erick , Haettich Bénédicte , Chalès Gérard , Auvinet Bernard , Eschard Jean‐Paul , Hamelin Jean‐Pierre , Baslé Michel‐Félix , Audran Maurice
Published: August 2002

Trabecular bone has been reported as having two‐dimensional (2‐D) fractal characteristics at the histological level, a finding correlated with biomechanical properties. However, several fractal dimensions (D) are known and computational ways to obtain them vary considerably. This study compared three algorithms on the same series of bone biopsies, to obtain the Kolmogorov, Minkowski–Bouligand, and mass‐radius fractal dimensions. The relationships with histomorphometric descriptors of the 2‐D trabecular architecture were investigated. Bone biopsies were obtained from 148 osteoporotic male patients. Bone volume (BV/TV), trabecular characteristics (Tb.N, Tb.Sp, Tb.Th), strut analysis, star volumes (marrow spaces and trabeculae), inter‐connectivity index, and Euler–Poincaré number were computed. The box‐counting method was used to obtain the Kolmogorov dimension (Dk), the dilatation method for the Minkowski–Bouligand dimension (DMB), and the sandbox for the mass‐radius dimension (DMR) and lacunarity (L). Logarithmic relationships were observed between BV/TV and the fractal dimensions. The best correlation was obtained with DMR and the lowest with DMB. Lacunarity was correlated with descriptors of the marrow cavities (ICI, star volume, Tb.Sp). Linear relationships were observed among the three fractal techniques which appeared highly correlated. A cluster analysis of all histomorphometric parameters provided a tree with three groups of descriptors: for trabeculae (Tb.Th, strut); for marrow cavities (Euler, ICI, Tb.Sp, star volume, L); and for the complexity of the network (Tb.N and the three D's). A sole fractal dimension cannot be used instead of the classic 2‐D descriptors of architecture; D rather reflects the complexity of branching trabeculae. Computation time is also an important determinant when choosing one of these methods. Copyright © 2001 John Wiley & Sons, Ltd.
Myomectomy during the first trimester associated with fetal limb anomalies and hydrocephalus in a twin pregnancy
Authors: Danzer E. , Holzgreve W. , Batukan C. , Miny P. , Tercanli S. , Hoesli I.
Published: August 2002

Objectives

To present the complications of a twin pregnancy after first trimester myomectomy and to discuss the possible etiologic relationship.

Case report

A 44‐year‐old primigravida with a dichorionic‐diamniotic twin pregnancy underwent myomectomy in another hospital at 12 weeks' gestational age. At 28 weeks the patient was referred to our unit because of ventriculomegaly and limb anomalies in the second twin. The patient underwent a Caesarean section at 37 weeks of gestation delivering twin A, a healthy female weighing 3235 g and twin B, a female weighing 2810 g with hydrocephalus and limb anomalies (clubfeet and hypoplasia of the nails and terminal phalanges). The placenta from twin A was normal, but in the placenta of twin B haemorrhage, thrombosis and infarction were noted.

Conclusions

Despite several reports of myomectomy in pregnancy without any problems for mother and fetus, the authors believe that myomectomy – especially in the first trimester – may be associated with the type of problems observed in the present case. The pathophysiological relationship between placental trauma and haemodynamic alterations as a possible cause of the malformations in twin B is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Raised maternal serum placenta growth factor concentration during the second trimester is associated with Down syndrome
Authors: Su Y. N. , Hsu J. J. , Lee C. N. , Cheng W. F. , Kung C. C. S. , Hsieh F. J.
Published: August 2002

Objectives

To compare early second‐trimester maternal serum placenta growth factor concentrations in Down syndrome pregnancies and those in normal pregnancies.

Methods

A case–control study was performed to evaluate the maternal serum placenta growth factor concentrations in 36 Down syndrome and 320 normal pregnancies with matched gestational age during the second trimester. For the detection of serum concentrations of placenta growth factor, a quantitative sandwich enzyme immunoassay technique (R & D Systems Inc., Minneapolis, Minnesota, USA) was performed.

Results

Using a multiple linear regression model, maternal serum placenta growth factor level was associated with gestational age (p<0.001) and the existence of Down syndrome pregnancy (p<0.001). After converting maternal serum placenta growth factor concentrations of each analyte to multiples of the appropriate gestational median (MoM), placenta growth factor MoM (p<0.001) was revealed to be an independent variable for Down syndrome pregnancies after adjusting for the effects of maternal age (p<0.001), free β‐hCG (p<0.001) and AFP (p=0.014) by multivariate logistic regression analysis.

Conclusions

Maternal serum placenta growth factor concentration was elevated in Down syndrome pregnancies during the early second trimester. Placenta growth factor might be a novel marker for maternal serum Down syndrome screening. Copyright © 2002 John Wiley & Sons, Ltd.
In utero therapy for lower urinary tract obstruction
Authors: Agarwal Sanjiv K. , Fisk Nicholas M.
Published: August 2002

Lower urinary tract obstruction has a significant impact on neonatal and child health. Pulmonary hyperplasia and renal impairment could be direct or indirect consequences of this condition leading to significant morbidity and mortality. Evaluation of fetuses with suspected lower urinary tract obstruction is performed not only to confirm the diagnosis but also to assess renal prognosis. Ultrasound examination and urinary analysis aid in the evaluation of these fetuses. The decision to perform fetal intervention in these cases is a difficult one. Vesico‒amniotic fetal shunting, open fetal surgery and more recently endoscopic fetal surgery for this condition are available as possible modalities of fetal intervention. Case selection for fetal intervention is extremely important in order to both avoid unnecessary intervention in those unlikely to survive, and also to avoid procedure related complications in fetuses likely to do well without intervention.

Vesico‒amniotic shunting has the advantage of bypassing the obstruction, however it is often associated with complications. Open fetal surgery is not usually recommended because of the complications and high fetal loss rate. Endoscopic surgery to visualise and treat the cause of lower urinary tract obstruction has been tried. Fetal endoscopic surgery is in its infancy and endoscopic procedures are limited to a few groups.

This current review addresses evaluation, case selection and therapeutic options for lower urinary tract obstruction in utero. It also discusses the limited data against which the efficacy of the various options can be assessed. The current state of fetal intervention is detailed in the present review. Copyright © 2001 John Wiley & Sons, Ltd.
Maternal serum leptin concentration during the second trimester of pregnancy: association with fetal chromosomal abnormalities
Authors: Rizos Demetrios , Hassiakos Demetrios , Grigori‐Kostaraki Panagiota , Sarandakou Angeliki , Botsis Demetrios , Salamalekis Emmanuel
Published: August 2002

Recent studies suggest that leptin, the product of the obese gene, is produced by the placenta during pregnancy. The present study addressed the question whether second trimester maternal serum leptin could be altered by fetal Down syndrome or Edwards syndrome. Maternal serum leptin concentrations were measured in 18 pregnancies complicated with Down syndrome, six pregnancies complicated with Edwards syndrome and 183 uncomplicated pregnancies during the second trimester of pregnancy. The present results demonstrate that leptin concentrations in uncomplicated pregnancies slightly decrease from the 16th week of pregnancy, reaching a minimum of 18.8 ng/ml around the 20th week, and then rapidly increase to 28.2 ng/ml by the 24th week. Leptin correlation with maternal body weight decreases from r=0.695 at 16–17 week of gestation to r=0.544 at >22 weeks of gestation. There was no significant difference between the mean MoMs of Down syndrome‐ (0.926) or Edwards syndrome‐ (0.960) affected pregnancies and normal pregnancies (1.002). A weak correlation (r=0.18, p<0.02) was observed between corrected leptin MoMs and human chorionic gonadotrophin (hCG) MoMs in normal pregnancies. It is assumed that around the 20th week of pregnancy placental leptin production is activated or at least is accelerated and it is added to the amount of leptin produced by maternal adipose tissue. Fetal Down syndrome or Edwards syndrome does not seem to alter maternal leptin concentration and therefore leptin cannot be used as a marker for these chromosomal abnormalities in the early second trimester of pregnancy. Copyright © 2002 John Wiley & Sons, Ltd.
Associations between a hydrophobically modified, degradable, poly(malic acid) and a β‐cyclodextrin polymer in solution
Authors: Moine Laurence , Amiel Catherine , Brown Wyn , Guerin Philippe
Published: August 2002

A new associating system has been elaborated from mixing a degradable polymer, poly(β‐malic acid‐co‐β‐ethyladamantyl malate), and a β‐cyclodextrin polymer in aqueous solution. Viscosity and dynamic light scattering measurements have been made on solutions of the single copolyester and of mixtures of both polymers. Studies on copolyesters with different percentages of hydrophobic groups (0–7.5%) show that a small proportion of the chains (less than 5% in weight) are aggregated in large structures (100 nm) which dominate the scattering intensity. The mixtures exhibit slow diffusive relaxation modes which correlate with a large viscosity enhancement at low concentration. These effects, which depend sensitively on pH, are attributed to the presence of polydisperse complexes of copolyester and β‐cyclodextrin polymer. The influence of pH, ionic strength, medium composition, and concentration were examined on the mixture of copolymers. It was found that the association properties are controlled by the net charge on the amphiphilic copolyester.

© 2001 Society of Chemical Industry
Oxidative copolymerization of indene with p‐tert‐butylstyrene: Synthesis, characterization, thermal analysis, and reactivity ratios
Authors: De Priyadarsi , Sathyanarayana D. N.
Published: August 2002

Copolyperoxides of indene and p‐tert‐butylstyrene of different compositions were synthesized by free‐radical‐initiated oxidative copolymerization. The compositions of the copolyperoxides, obtained from 1H and 13C NMR spectra, were used to calculate the reactivity ratios of the monomers. The reactivity ratios indicated a larger proportion of indene units in random placement in the copolyperoxides. Thermal‐degradation studies by differential scanning calorimetry and electron‐impact mass spectrometry supported alternating peroxide units in the copolymer backbone. The activation energy for thermal degradation suggested that the degradation was dependent on the dissociation of the peroxide (OO) bonds in the backbone of the copolyperoxide chain. The flexibility of the copolyperoxides was examined in terms of the glass‐transition temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 9–18, 2002
Reactivity ratios for the terpolymerization of methyl methacrylate, vinyl acetate, and molecular oxygen
Authors: De Priyadarsi , Sathyanarayana D. N.
Published: August 2002

The copolymerization of methyl methacrylate (MMA) and vinyl acetate (VAc) under high oxygen pressure was investigated. Copolyperoxides of various compositions were synthesized by the free‐radical‐initiated oxidative copolymerization of MMA and VAc monomers. The copolyperoxide compositions obtained from 1H and 13C NMR spectra were used for determining the reactivity ratios of the monomers. The reactivity ratios indicated a larger proportion of MMA units statistically placed in the copolyperoxides. A theoretical analysis based on semiempirical AM1 calculations was performed to support the reactivity ratios. NMR studies showed irregularities in the copolyperoxide chain due to the cleavage reactions of the propagating peroxide radical. Thermal analyses of the copolyperoxides by differential scanning calorimetry gave evidence for the presence of alternating peroxide units in the copolyperoxide chain. The activation energies of thermal degradation suggested that degradation was controlled by the dissociation of the peroxide (OO) bond in the backbone of the copolyperoxide chain. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 564–572, 2002; DOI 10.1002/pola.10115
Reactive blending of functional polysiloxanes with poly(butylene terephthalate): Clarification of reaction mechanisms and kinetics from a model compound study
Authors: Fustin C. A. , Sclavons M. , Verhelst V. , Vermylen V. , Bebelman S. , Merlin P. , Bailly C.
Published: August 2002

We clarify the reaction mechanisms and kinetics in melt‐reacted blends consisting of functional polysiloxanes and poly(butylene terephthalate) (PBT) with a model compound study. As models for polysiloxanes, we have selected two monodisperse ω‐functionalized siloxane oligomers with SiH and Sivinyl moieties. To mimic PBT, we have chosen low molecular weight compounds representative for in‐chain and end‐functional groups of the polymer; ester, carboxylic acid, alcohol, and vinyl. Uncatalyzed and platinum‐catalyzed reactions have been performed in sealed vials. Reaction products have been characterized by gradient polymer elution chromatography, Fourier transform infrared spectroscopy, and size exclusion chromatography. PBT functional groups reactive toward functional siloxane oligomers at high temperatures in the presence and absence of a catalyst have been identified, and an estimate of relative reaction kinetics has been provided. We suggest reaction mechanisms compatible with our results and with literature data. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1952–1961, 2002
Absolute absorption measurements of polymer films for optical waveguide applications by photothermal deflection spectroscopy
Authors: Wu Liu‐Ming , Knoesen André
Published: August 2002

A self‐contained experimental technique is proposed for measuring the absolute optical absorption spectra, thermal diffusivity, and thermal conductivity of polymer thin films. The technique is based on photothermal deflection spectroscopy and provides sensitivity that is high enough to quantify the very small optical absorption losses in polymer films used for optical waveguide applications. The capabilities of the technique are demonstrated with measurements performed on thin films of poly(methyl methacrylate) and a fluorinated polymer (CYTOP). An error analysis is presented, and the factors are discussed that influence the accuracy of the technique. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2717–2726, 2001
Indentation of poly(methyl methacrylate) under high‐pressure gases
Authors: Flichy N. M. B. , Kazarian S. G. , Lawrence C. J. , Briscoe B. J.
Published: August 2002

The variation of the indentation hardness of a high molecular weight poly(methyl methacrylate) (PMMA) subjected to CO2 and Ar at high pressure was measured in situ. The samples were subjected to gas exposure for 3 h at 40 °C before a conical indenter of an included angle at 105 °, with a fixed load of 0.237 kg, was applied for a loading time of 60 s. The data show that both CO2 and Ar reduce the hardness of PMMA to a comparable extent at low pressures. The hardness of PMMA subjected to Ar indicates a minimum at about 4 MPa and then increases. CO2 produced a monotone decreasing trend in hardness in the pressure range studied, and the glass‐transition temperature (Tg) was achieved at about 6.0 MPa. The change in hardness is attributed to plasticization of the polymer matrix that is more extensive for CO2. The relationship between the change in hardness for this PMMA subjected to high‐pressure CO2, the corresponding change in the Tg, and the associated swelling of the polymer is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 3020–3028, 2001
Influence of the β‐crystalline phase on the mechanical properties of unfilled and calcium carbonate‐filled polypropylene: Ductile cracking and impact behavior
Authors: Labour T. , Vigier G. , Séguéla R. , Gauthier C. , Orange G. , Bomal Y.
Published: August 2002

The β‐crystalline form of isotactic poly(propylene) (PP) has been long recognized to have a greater mechanical absorption capacity than the α‐crystalline form. This is of major importance for improving impact properties and crack resistance of injection‐molding parts. Unfilled PP samples together with calcium carbonate‐filled PP samples having various β/α‐phase ratios, with nearly constant morphological parameters, have been investigated from the standpoint of ductile crack propagation and impact behavior. The presence of the β‐crystalline phase turned out to improve both properties. The β spherulites are notably more prone to craze initiation than α spherulites that display a propensity for cracking. Subsequent crack propagation appears to be faster in the latter ones. The plastic zone ahead from the crack tip broadens, and the specific plastic energy increases with increasing β‐phase content. The lower elastic limit of the β phase is likely to promote the early crazing. However, the suspected higher density of tie molecules in β spherulites provides more numerous and stiffer microfibrils. The impact strength of PP is also improved by the presence of β crystals as a result of greater energy‐absorption capabilities. However, filled samples turned out insensitive to the β phase. A discussion is made about the origins of the β‐phase‐induced improvement of the mechanical properties. The possible role of the β → α transition is also explained. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 31–42, 2002
Mesoscopic modeling of the polymerization, morphology, and crystallization of stereoblock and stereoregular polypropylenes
Authors: Madkour Tarek M. , Mark James E.
Published: August 2002

Thermoplastic elastomers require domains that act as physical crosslinks, and these can be either glassy regions or crystallites. For crystallites in a polymer such as polypropylene (PP), the challenge is to develop polymerizations that form the long stereoregular chain sequences required to produce crystallites large enough to act as stable temporary crosslinks but not so many of them that the material becomes a significantly crystalline thermoplastic rather than an elastomer. For PP, the requirement is for long isotactic sequences within predominantly elastomeric atactic chains, and catalysts required to achieve such an unusual stereoblock structure are now available. This provided encouragement for the simulations described herein that illustrate some relationships between polymerization mechanisms and distributions of isotactic sequences (particularly those long enough to crystallize). A Windle‐type Monte Carlo algorithm was then applied to arrays of the representative PP chains in searches for matches of crystallizable sequences. This approach provided estimates of degrees of crystallinity, melting points, interfacial free energies, standard free energies of fusion, and Young's moduli at small extensions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 840–853, 2002
Diffusion of oxygen and carbon dioxide in thermally crystallized syndiotactic polystyrene
Authors: Hodge K. , Prodpran T. , Shenogina N. B. , Nazarenko S.
Published: August 2002

The diffusion, solubility, and permeability behavior of oxygen and carbon dioxide were studied in amorphous and semicrystalline syndiotactic polystyrene (s‐PS). The crystallinity was induced in s‐PS by crystallization from the melt and cold crystallization. Crystalline s‐PS exhibited very different gas permeation behavior depending on the crystallization conditions. The behavior was attributed to the formation of different isomorphic crystalline forms in the solid‐state structure of this polymer. The β crystalline form was virtually impermeable for the transport of oxygen and carbon dioxide. In contrast, the α crystalline form was highly permeable for the transport of oxygen and carbon dioxide. High gas permeability of the α crystals was attributed to the loose crystalline structure of this crystalline form containing nanochannels oriented parallel to the polymer chain direction. A model describing the diffusion and permeability of gas molecules in the composite permeation medium, consisting of the amorphous matrix and the dispersed crystalline phase with nanochannels, was proposed. Cold crystallization of s‐PS led to the formation of a complex ordered phase and resulted in complex permeation behavior. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2519–2538, 2001
Bronchiolitis obliterans organizing pneumonia (BOOP) in a child with mild‐to‐moderate asthma: Evidence of mast cell and eosinophil recruitment in lung specimens
Authors: Barbato Angelo , Panizzolo Cristina , D'Amore Emanuele S.G. , La Rosa Mario , Saetta Marina
Published: August 2002

Bronchiolitis obliterans with organizing pneumonia (BOOP) is rarely described in children and little is known about its pathogenesis. This paper reports on an 11‐year‐old patient suffering from mild‐to‐moderate asthma. He presented with a retrocardiac density at chest computed tomography scan that was slow to resolve and failed to respond to antibiotic therapy. Open lung biopsy revealed a histological picture with buds of granulation tissue in respiratory bronchioles and alveolar ducts, with organized extensions into the alveoli. The use of monoclonal antibodies on biopsy specimens demonstrated the presence of an inflammatory process affecting not only the thickened alveolar walls, but also the remaining lung parenchyma, the pulmonary arteries, and the bronchioles. The inflammatory infiltrate consisted mainly of mast cells and eosinophils. The clinical condition improved with steroid therapy. To the best of the authors' knowledge, this is the first report of BOOP in an asthmatic child with recruitment of mast cells and eosinophils documented by using monoclonal antibodies. Pediatr Pulmonol. 2001; 31:394–397. © 2001 Wiley‐Liss, Inc.
Polymorphic repeats in the androgen receptor gene in high‐risk sibships
Authors: Miller Elizabeth A. , Stanford Janet L. , Hsu Li , Noonan Elizabeth , Ostrander Elaine A.
Published: August 2002

Background

Genetic susceptibility may explain some familial clusters of prostate cancer. The polymorphic androgen receptor (AR) gene, which mediates androgen activity in the prostate, is a candidate gene that may influence predisposition to the disease.

Methods

We analyzed the polymorphic (CAG)n and (GGN)n repeats within the AR gene in men from 51 high‐risk prostate cancer sibships, which included at least one affected and one unaffected man (n = 210). We compared repeat lengths of men with prostate cancer (n = 140) to their brothers (n = 70) without disease, stratified by median age at diagnosis of affected men within each sibship. Conditional logistic regression was used to compute odds ratios (OR) and 95% confidence intervals to evaluate associations between prostate cancer and repeat length.

Results

The OR for prostate cancer associated with short (CAG)n repeats (<22) compared to longer repeats (≥22) was 1.13 (95% CI 0.5–2.4) overall, but was higher in sibships with a median age of <66 years at diagnosis (OR = 1.72, 95% CI 0.5–6.0). The (GGN)n array also was not associated with prostate cancer in general. However, in older men (≥66 years), there was a modest elevation in risk (OR = 1.56, 95% CI 0.6–4.1) among those with short repeats (GGN of ≤16). Men with both a short (CAG)n (<22) and a short (GGN)n (≤16) array were not at higher risk (OR = 1.06) compared to men with two long repeats [(CAG)n ≥22 and (GGN)n >16)].

Conclusions

These results suggest that the (CAG)n and (GGN)n repeats in the AR gene do not play a major role in familial prostate cancer. Prostate 48:200–205, 2001. © 2001 Wiley‐Liss, Inc.
Coupling of ligand binding and dimerization of helix‐loop‐helix peptides: Spectroscopic and sedimentation analyses of calbindin D9k EF‐hands
Authors: Julenius Karin , Robblee James , Thulin Eva , Finn Bryan E. , Fairman Robert , Linse Sara
Published: August 2002

Isolated Ca2+‐binding EF‐hand peptides have a tendency to dimerize. This study is an attempt to account for the coupled equilibria of Ca2+‐binding and peptide association for two EF‐hands with strikingly different loop sequence and net charge. We have studied each of the two separate EF‐hand fragments from calbindin D9k. A series of Ca2+‐titrations at different peptide concentrations were monitored by CD and fluorescence spectroscopy. All data were fitted simultaneously to both a complete model of all possible equilibrium intermediates and a reduced model not including dimerization in the absence of Ca2+. Analytical ultracentrifugation shows that the peptides may occur as monomers or dimers depending on the solution conditions. Our results show strikingly different behavior for the two EF‐hands. The fragment containing the N‐terminal EF‐hand shows a strong tendency to dimerize in the Ca2+‐bound state. The average Ca2+‐affinity is 3.5 orders of magnitude lower than for the intact protein. We observe a large apparent cooperativity of Ca2+ binding for the overall process from Ca2+‐free monomer to fully loaded dimer, showing that a Ca2+‐free EF‐hand folds upon dimerization to a Ca2+‐bound EF‐hand, thereby presenting a preformed binding site to the second Ca2+‐ion. The C‐terminal EF‐hand shows a much smaller tendency to dimerize, which may be related to its larger net negative charge. In spite of the differences in dimerization behavior, the Ca2+ affinities of both EF‐hand fragments are similar and in the range lgK = 4.6–5.3. Proteins 2002;47:323–333. © 2002 Wiley‐Liss, Inc.
Application of coupled liquid chromatography–mass spectrometry in photolysis studies of the herbicide triflusulfuron‐methyl
Authors: Chafik Nourrddine , Mansour Mohammed , Elamrani Btissam , Schramm Karl‐Werner , Kettrup Antonius , Elamrani M Khalid
Published: August 2002

The photochemical fate of the herbicide triflusulfuron‐methyl in aqueous solution under UV light (λ > 290 nm) was investigated. Nine photoproducts were detected and tentatively identified by LC/MS and LC/MS/MS analysis. The main routes of degradation involve the cleavage and/or contraction of the sulfonylurea bridge with the elimination of sulfur dioxide, which increases the acidity of the reaction medium. On the basis of the results obtained a photodegradation pathway is proposed.

© 2001 Society of Chemical Industry
Laboratory studies to assess the risk of development of resistance to zoxamide
Authors: Young David H , Spiewak Sandra L , Slawecki Richard A
Published: August 2002

Laboratory studies were conducted to evaluate the risk of developing field resistance to zoxamide, a new Oomycete fungicide which acts on microtubules. Zoxamide, metalaxyl and dimethomorph were compared with respect to the ease with which fungicide‐resistant mutants could be isolated and their level of resistance. Attempts to generate mutants of Phytophthora capsici and P infestans with resistance to zoxamide by mycelial adaptation on fungicide‐amended medium were unsuccessful. Similarly, changes in sensitivity to zoxamide were small (resistance factors ≤2.2) in mutants of P capsici isolated by chemical mutagenesis of zoospore cysts. In parallel experiments with metalaxyl, highly resistant mutants were obtained using both adaptation (P capsici or P infestans) and chemical mutagenesis (P capsici). For dimethomorph, chemical mutagenesis (P capsici) yielded moderately resistant mutants (maximum resistance factor = 20.9), and adaptation (P capsici or P infestans) did not induce resistance. It is proposed that failure to isolate mutants resistant to zoxamide results from the diploid nature of Oomycete fungi and the likelihood that target‐site mutations would produce a recessive phenotype. Our studies suggest that the risk of a highly resistant pathogen population developing rapidly in the field is much lower for zoxamide than for metalaxyl. However, as with any site‐specific fungicide, appropriate precautions against resistance development should be taken.

© 2001 Society of Chemical Industry
Intersections in steel shell structures
Authors: Teng J G
Published: August 2002

Cylinders, cones, spheres and tori are some of the common basic shell elements. Steel shell structures such as silos, tanks, pressure vessels, offshore platforms, chimneys and tubular towers generally consist of two or more of these basic shell elements. Axisymmetric intersections featuring meridional slope mismatches between the connected elements are common features in steel shell structures. High bending and circumferential membrane stresses are developed in these intersections, and their buckling and collapse strengths are a key design consideration. This paper presents a summary of recent research on the stress, stability and strength of axisymmetric steel shell intersections. Particular attention is paid to intersections formed from cylindrical and conical segments as these are more common and have been more extensively researched. A simple approximate method for extrapolating the knowledge gained on these intersections to those containing curved shell segments is also suggested.
Modulatory influence of Andrographis paniculata on mouse hepatic and extrahepatic carcinogen metabolizing enzymes and antioxidant status
Authors: Singh Rana P. , Banerjee S. , Rao A. Ramesha
Published: August 2002

The effects of two doses (50 and 100 mg/kg body wt/day for 14 days) of an 80% hydroalcohol extract of Andrographis paniculata and butylated hydroxyanisole (BHA) were examined on drug metabolizing enzymes, antioxidant enzymes, glutathione content, lactate dehydrogenase (LDH) and lipid peroxidation in the liver of Swiss albino mice (6–8 weeks old). The effect of the extract and BHA were also examined on lung, kidney and forestomach for the activities of glutathione S‐transferase (GST), DT‐diaphorase (DTD), superoxide dismutase (SOD) and catalase. A significant increase in the levels of acid soluble sulphydryl (‐SH) content, cytochrome P450, cytochrome P450 reductase, cytochrome b5 reductase, GST, DTD and SOD were observed at both dose levels of extract treatment while catalase, glutathione peroxidase and glutathione reductase (GR) showed significant increases only at the higher dose in the liver. Both Andrographis treated groups showed a significant decrease in activity of LDH and malondialdehyde (MDA) formation. BHA treated mice showed a significant increase in the levels of cytochrome b5, GST, DTD, ‐SH content, GR and catalase in liver; while LDH and MDA levels were reduced significantly compared with their control values. In the lung, SOD, catalase and DTD, in the kidney catalase, DTD and GST, and in the forestomach SOD and DTD showed a significant increase at both dose levels of treatment. In BHA treated mice GST, DTD and catalase were significantly induced in the lung and along with these enzymes SOD was also induced in the kidney. In the case of the forestomach of BHA treated mice GST, DTD and SOD were enhanced significantly. These findings indicate the chemopreventive potential of Andrographis paniculata against chemotoxicity including carcinogenicity. Copyright © 2001 John Wiley & Sons, Ltd.
Adaptogenic activity of a novel, withanolide‐free aqueous fraction from the roots of Withania somnifera Dun.
Authors: Singh B. , Saxena A. K. , Chandan B. K. , Gupta D. K. , Bhutani K. K. , Anand K. K.
Published: August 2002

The practitioners of the traditional Indian system of medicine regard Withania somnifera Dun. as the ‘Indian ginseng’. A new withanolide‐free aqueous fraction was isolated from the roots of this plant and was evaluated for putative antistress activity against a battery of tests such as hypoxia time, antifatigue effect, swimming performance time, swimming induced gastric ulceration and hypothermia, immobilization induced gastric ulceration, autoanalgesia and biochemical changes in the adrenal glands. This bioactive fraction exhibited significant antistress activity in a dose‐related manner in all the parameters studied. The extract of Withania somnifera root (a commercial preparation available locally) was used to compare the results. A preliminary acute toxicity study in mice showed a good margin of safety. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluation of plastic packages for guava refrigerated preservation
Authors: Jacomino Angelo Pedro , Kluge Ricardo Alfredo , Sarantópoulos Claire Isabel Grígoli de Luca , Sigrist José Maria Monteiro
Published: August 2002

Guavas cv. ‘Kumagai’ were packed in several plastic materials and stored at 10°C and 85–90% relative humidity (RH) for 7, 14, 21 and 28 days (+3 days at 25°C). The plastic materials studied were: multilayer co‐extruded polyolephine film with selective permeability (PSP), low‐density polyethylene film (LDPE), LDPE film with mineral incorporation (LDPEm) and heat‐shrinkable polyolephine film (SHR). Guavas not packed were taken as control samples. The physicochemical characteristics of the fruits, O2 and CO2 transmission rates of the packaging materials and gas composition at the package headspace were evaluated. The LDPE film, 69 µm in thickness, with the lowest permeability to both O2 and CO2, led to anaerobiosis and high CO2 concentration inside the packages and promoted physiological disturbances and changes in fruit flavour. The SHR film, 15 µm in thickness, was the most permeable to CO2 and had quite high O2 transmission, which modified the inner atmosphere of the packages slightly. The fruits packed in this film showed a poorer quality than the controls, possibly due to the heat produced during the shrinking of the film. The LDPEm film, 24 µm in thickness, was almost as permeable to CO2 but had reduced O2 transmission, promoting an atmosphere of equilibrium of 3% O2 and 4.5% CO2. Fruits packed in this film kept their skin colour and pulp firmness, suitable for consumption up to 14 days. The PSP film, 35 µm in thickness, had the greatest O2 transmission but just over half of the CO2 transmission of LDPEm, promoting an atmosphere of equilibrium of 0.5% O2 and 4.5% CO2 inside the packages. Fruits packed in such packages kept their physicochemical characteristics up to 21 days. Copyright © 2001 John Wiley & Sons, Ltd.
Note on the theory of bifurcation of chemical reactions
Authors: Palmeiro Raul , Frutos Luis Manuel , Castaño Obis
Published: August 2002

In the present communication two existing definitions of valley ridge inflection, (VRI), point, one attributed to Valtazanos and Ruedenberg and the other one to Basilevsky are discussed. From our study we conclude that both definitions are not equivalent, and we demonstrate in which cases it occurs. However, they are used without any distinction in the bibliography. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Bound states of oscillators in infinite and finite domains: A semiclassical study
Authors: Mukhopadhyay S. , Bhattacharyya K.
Published: August 2002

By involving the uncertainty product along with a semiclassical requirement for observables, a simple variational scheme is employed to extract major features of bound states of systems in (−∞,∞) and the same of systems confined in (−L,L). Special attention is paid to perturbative studies on the asymptotic behavior of energies for oscillators in infinite domains and dependence of energy spectra of oscillators in finite domains on various system parameters. A corrected form of the virial theorem is obtained in the latter case. The governing equations for quantum isothermal and adiabatic processes, derived recently, are also shown to be modified for general confined oscillator systems and closed‐form expressions are found. These results are useful in dealing with the quantum Carnot cycles. Advantages of the present route over other semiclassical strategies are stressed. Pilot calculations demonstrate nicely the efficacy of the endeavor under various situations. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001