bluuebunny/crossref_metadata_2025 huggingface dataset:
Block Copolymers via ROMP – Awakening the Sleeping Beauty
Authors: Riegler Silvia , Slugovc Christian , Trimmel Gregor , Stelzer Franz
Published: November 2004

This paper on recent developments in block copolymerisation using ring‐opening metathesis polymerisation summarizes about 60 publications and discusses current trends.
Properties of Star‐Branched Polymer Chains Near a Surface
Authors: Sikorski Andrzej , Romiszowski Piotr
Published: November 2004

We considered two model systems of star‐branched polymers near an impenetrable surface. The model chains were constructed on a simple cubic lattice. Each star polymer consisted of f = 3 arms of equal length and the total number of segments was up to 799. The excluded volume effect was included into these models only and therefore the system was studied at good solvent conditions. In the first model system polymer chain was terminally attached with one arm to the surface. The grafted arm could slide along the surface. In the second system the star‐branched chain was adsorbed on the surface and the strength of adsorption was were varied. The simulations were performed using the dynamic Monte Carlo method with local changes of chain conformations. The internal and local structures of a polymer layer were determined. The lateral diffusion and internal mobility of star‐branched chains were studied as a function of strength of adsorption and the chain length. The lateral diffusion and internal mobility of star‐branched chains were studied as a function of strength of adsorption and the chain length. It was shown that the behavior of grafted and weakly adsorbed chains was similar to that of a free three‐dimensional polymer, while the strongly adsorbed chains behave as a two‐dimensional system.
Computer Simulations of Grafted Amphiphilic Polymer Chains
Authors: Sikorski Andrzej , Romiszowski Piotr
Published: November 2004

We designed a simple model of a polymer layer formed by many chains. Each chain was built on a flexible [310] lattice. All chains were terminally attached to an impenetrable surface and the lateral motion of the entire chain was enabled. The force field used consisted of the contact potential regarding attractive interaction as well as the excluded volume effect. between polymer segments with short‐range repulsion. It was assumed that the chains were built of hydrophilic and hydrophobic segments. The Monte Carlo simulations of this model were carried out using the Metropolis algorithm. The influence of both the grafting density and the temperature on static properties of the system were studied and discussed. The size, shape and structure of the polymer film formed near the surface were determined. The low temperature structures formed by the brush were described.
Electrospinning P(LLA‐CL) Nanofiber: A Tubular Scaffold Fabrication with Circumferential Alignment
Authors: Mo Xiumei , Weber Hans‐Joachim
Published: November 2004

In this paper a synthetic Poly(L‐lactic‐co‐ϵ‐caprolactone) [P(LLA‐CL)] (75:25) copolymer has been fabricated into a nanofibrous structure by electrospinning. The polymer crystal structure has been investigated by DSC and x‐ray diffraction method. During electrospinning at room temperature, a crystallization of LLA sequence in the P(LLA‐CL) copolymer could not form, while a relatively regular arrangement of CL sequence was observed. In order to obtain a tubular scaffold, a rotating mandrel was designed to collect the fiber, so that the tubular scaffold can be retrieved from the mandrel with an inner diameter same as that of the outer diameter of the mandrel. An auxiliary electrode with a sharp edge and a negative charge was set under the mandrel to guide the fiber deposition on the mandrel. When the sharp edge bar was vertical to the rotating axle of the mandrel and just beneath the spinning nozzle, nanofibers with circumferential alignment were obtained. With this method it is possible to obtain a tubular scaffold with suitable fiber alignment for blood vessel tissue engineering.
Surface wave scattering by a rectangular impedance cylinder located on a reactive plane
Authors: Tayyar İsmail Hakkı , Aksoy Serkan , Alkumru Ali
Published: November 2004

The electromagnetic scattering of the surface wave by a rectangular impedance cylinder located on an infinite reactive plane is considered for the case that the impedances of the horizontal and vertical sides of the cylinder can have different values. Firstly, the diffraction problem is reduced into a modified Wiener–Hopf equation of the third kind and then solved approximately. The solution contains branch‐cut integrals and two infinite sets of constants satisfying two infinite systems of linear algebraic equations. The approximate analytical or numerical evaluations of corresponding integrals and numerical solution of the linear algebraic equation systems are obtained for various values of parameters such as the surface reactance of the plane, the vertical and horizontal wall impedances, the width and the height of the cylinder. Copyright © 2004 John Wiley & Sons, Ltd.
Reduction of residual dipolar interaction in cartilage by spin‐lock technique
Authors: Akella Sarma V.S. , Regatte Ravinder R. , Wheaton Andrew J. , Borthakur Arijitt , Reddy Ravinder
Published: November 2004

The influence of radiofrequency (RF) spin‐lock pulse on the laminar appearance of articular cartilage in MR images was investigated. Spin‐lock MRI experiments were performed on bovine cartilage plugs on a 4.7 Tesla small‐bore MRI scanner, and on human knee cartilage in vivo on a 1.5 Tesla clinical scanner. When the normal to the surface of cartilage was parallel to B0, a typical laminar appearence was exhibited in T2‐weighted images of cartilage plugs, but was absent in T1ρ‐weighted images of the same plugs. At the “magic angle” orientation (when the normal to the surface of cartilage was 54.7° with respect to B0), neither the T2 nor the T1ρ images demonstrated laminae. At the same time, T1ρ values were greater than T2 at both orientations throughout the cartilage. T1ρ dispersion (i.e., the dependence of the relaxation rate on the spin‐lock frequency ω1) was observed, which reached a steady‐state value of close to 2 kHz in both parallel and magic‐angle orientations. These results suggest that residual dipolar interaction from motionally‐restricted water and relaxation processes, such as chemical exchange, contribute to T1ρ dispersion in cartilage. Further, one can reduce the laminar appearance in human articular cartilage by applying spin‐lock RF pulses, which may lead to a more accurate diagnosis of degenerative changes in cartilage. Magn Reson Med 52:1103–1109, 2004. © 2004 Wiley‐Liss, Inc.
RF‐induced temperature elevation along metallic wires in clinical magnetic resonance imaging: Influence of diameter and length
Authors: Armenean Cristina , Perrin Emmanuel , Armenean Mircea , Beuf Olivier , Pilleul Frank , Saint‐Jalmes Hervé
Published: November 2004

With the development of interventional MRI, heating of biological tissues along the metallic wires in the MRI scanner has become an important issue. To assess thermal response to RF exposure during MRI, we studied the temperature elevation near nonmagnetic metallic wires. All tests were performed on a 1.5 T clinical scanner. Four experiments were conducted to investigate the effects of the wire diameter, the excitation flip angle, the temperature distribution along the wire, and the wire length. Electromagnetic simulations of the experimental setup were made with the use of commercial method of moments (MoM) software and numerical simulations of Hallén's equations. Comparisons between measured and calculated values of the electric field are presented. This study demonstrates that 1) temperature decreases with the diameter of the wire,2)temperature increases quadratically with the excitation flip angle, 3) heating occurs not only at the tip but also along the wire, and 4) the heating peaks are not obtained for the classical resonant length multiple of λ/4 (where λ is the RF field wavelength). In addition, significant and rapid heating increases were observed in the close vicinity of the wire. Magn Reson Med 52:1200–1206, 2004. © 2004 Wiley‐Liss, Inc.
Calibration of echo‐planar 2D‐selective RF excitation pulses
Authors: Oelhafen Markus , Pruessmann Klaas P. , Kozerke Sebastian , Boesiger Peter
Published: November 2004

Echo‐planar radiofrequency (RF) pulses (EPP) are increasingly being used for 2D‐selective excitation in MRI. Pulse schemes of this kind are susceptible to eddy‐current effects, timing imperfections, and anisotropy of the gradient system. As a consequence, practical EPP implementations have been restricted to robust fly‐back strategies that use only every other leg of the echo‐planar trajectory for RF transmission. The present work is dedicated to enabling forward‐backward EPP with RF transmission during each k‐space segment, hence doubling the pulses' time efficiency. This is accomplished by comprehensive pulse calibration based on preparatory measurements of the system imperfections, including potential gradient anisotropy. The effectiveness of the method is demonstrated in vitro and in vivo. By doubling the speed of k‐space coverage, the proposed method enhances the potential of EPP for numerous applications. For example, motion‐sensitive techniques benefit from shorter feasible echo times (TEs) and improved excitation profiles resulting from reduced in‐pulse motion. In sequences with fast repetition, shorter EPP help reduce the overall scan duration. Alternatively, the higher time efficiency of forward‐backward EPP can enhance their spatial selectivity. Magn Reson Med 52:1136–1145, 2004. © 2004 Wiley‐Liss, Inc.
Point spread function mapping with parallel imaging techniques and high acceleration factors: Fast, robust, and flexible method for echo‐planar imaging distortion correction
Authors: Zaitsev M. , Hennig J. , Speck O.
Published: November 2004

Echo‐planar imaging (EPI) is an ultrafast magnetic resonance (MR) imaging technique prone to geometric distortions. Various correction techniques have been developed to remedy these distortions. Here improvements of the point spread function (PSF) mapping approach are presented, which enable reliable and fully automated distortion correction of echo‐planar images at high field strengths. The novel method is fully compatible with EPI acquisitions using parallel imaging. The applicability of parallel imaging to further accelerate PSF acquisition is shown. The possibility of collecting PSF data sets with total acceleration factors higher than the number of coil elements is demonstrated. Additionally, a new approach to visualize and interpret distortions in the context of various imaging and reconstruction methods based on the PSF is proposed. The reliable performance of the PSF mapping technique is demonstrated on phantom and volunteer scans at field strengths of up to 4 T. Magn Reson Med 52:1156–1166, 2004. © 2004 Wiley‐Liss, Inc.
Human myeloperoxidase: A potential target for molecular MR imaging in atherosclerosis
Authors: Chen John W. , Pham Wellington , Weissleder Ralph , Bogdanov Alexei
Published: November 2004

Plaque rupture in atherosclerotic disease is the major cause of morbidity and correlates well with myeloperoxidase (MPO) secretion by activated neutrophils and macrophages in humans. We hypothesized that paramagnetic electron donor compounds that rapidly oxidize and polymerize in the presence of MPO could be designed to enable imaging of local MPO activity levels in arterial segments at risk. Several potential substrates for MPO were synthesized and tested. One lead compound consisting of a covalent conjugate of GdDOTA and serotonin (3‐(2‐aminoethyl)‐5‐hydroxyindole) was efficiently polymerized in the presence of human neutrophil MPO resulting in a 70–100% increase in proton relaxivity. As a result, we were able to demonstrate MPO activity in enzyme solutions and in a model tissue‐like system. These studies suggest that activatable paramagnetic MR imaging agents can be used to directly image MPO activity. Magn Reson Med 52:1021–1028, 2004. © 2004 Wiley‐Liss, Inc.
New modeling and experimental framework to characterize hindered and restricted water diffusion in brain white matter
Authors: Assaf Yaniv , Freidlin Raisa Z. , Rohde Gustavo K. , Basser Peter J.
Published: November 2004

To characterize anisotropic water diffusion in brain white matter, a theoretical framework is proposed that combines hindered and restricted models of water diffusion (CHARMED) and an experimental methodology that embodies features of diffusion tensor andq‐space MRI. This model contains a hindered extra‐axonal compartment, whose diffusion properties are characterized by an effective diffusion tensor, and an intra‐axonal compartment, whose diffusion properties are characterized by a restricted model of diffusion within cylinders. The hindered model primarily explains the Gaussian signal attenuation observed at lowbvalues; the restricted non‐Gaussian model does so at highb. Both high and lowbdata obtained along different directions are required to estimate various microstructural parameters of the composite model, such as the nerve fiber orientation(s), theT2‐weighted extra‐ and intra‐axonal volume fractions, and principal diffusivities. The proposed model provides a description of restricted diffusion in 3D given by a 3D probability distribution (average propagator), which is obtained by 3D Fourier transformation of the estimated signal attenuation profile. The new model is tested using synthetic phantoms and validated on excised spinal cord tissue. This framework shows promise in determining the orientations of two or more fiber compartments more precisely and accurately than with diffusion tensor imaging. Magn Reson Med 52:965–978, 2004. Published 2004 Wiley‐Liss, Inc.
Automatic spatial and temporal temperature control for MR‐guided focused ultrasound using fast 3D MR thermometry and multispiral trajectory of the focal point
Authors: Mougenot Charles , Salomir Rares , Palussière Jean , Grenier Nicolas , Moonen Chrit T.W.
Published: November 2004

Of the different modalities to induce local hyperthermia, focused ultrasound is the only noninvasive technology available at the moment. In addition to the 3D localization of the target region, it has been shown that MRI can provide real‐time thermometry and allows online, automatic control of temperature evolution of the focal point. Treatment of a large tissue volume (as compared to the focal spot size, i.e., the ultrasound wavelength) can be achieved rapidly by moving the focal point along an inside‐out spiral trajectory. It has been shown previously that under linear conditions of energy deposition versus temperature, the spatial profile of the temperature within a large area can be controlled. In this study, a proportional, integral, and derivative (PID) spatial‐and‐temporal controller is described for the control of the temperature evolution within the target region under more variable conditions. The aim was to reach a predefined temperature profile after a few successive trajectories. Heat conduction in tissue is exploited to obtain a uniform temperature increase in a volume using discrete sonications without any waiting time. Input data sets consisted of 3D temperature maps provided online by a MR scanner. For each new trajectory, the controller recalculates the number of sonications per surface unit (spatial density of points describing the trajectory) and the applied power. Its performance was tested ex vivo and in vivo. Diameters of the target region ranged from 9 mm to 19 mm. Targeted temperature increase ranged from +8°C to +18°C. Spatiotemporal temperature control showed good stability and fast convergence, for both circular and elliptic ROIs. Magn Reson Med 52:1005–1015, 2004. © 2004 Wiley‐Liss, Inc.
Intravoxel distribution of DWI decay rates reveals C6 glioma invasion in rat brain
Authors: Bennett Kevin M. , Hyde James S. , Rand Scott D. , Bennett Raoqiong , Krouwer Hendrikus G. J. , Rebro Kelly J. , Schmainda Kathleen M.
Published: November 2004

The hypothesis was tested that the intravoxel distribution of water diffusion rates, as measured with a stretched‐exponential model of diffusion‐weighted imaging (DWI), is a marker of brain tumor invasion. Eight rats underwent intracerebral inoculation of C6 glioma cells. In three rats, cells were labeled with a fluorescent dye for microscopy. One rat was inoculated with a saline solution, and five more rats were imaged without inoculation as controls. Five healthy uninoculated rats were also imaged. DWI was performed 14–15 days after inoculation, with diffusion‐weighting factor b = 500 to 6500 sec/mm2, and the resulting signal attenuation was fitted with the stretched‐exponential model. The heterogeneity index values were significantly lower (P < 0.05) in the peritumor ROI than in normal gray matter and significantly higher than in normal white matter. The distributed diffusion coefficient values were significantly lower than in normal white matter or normal gray matter. Fluorescence microscopy confirmed the presence of tumors in the peritumor region that could be histologically distinguished from the main tumor mass. There was no change in proton density or T2‐weighted images in the peritumor region, making vasogenic edema unlikely as a source of contrast. It is therefore thought that the heterogeneity parameter α is a marker of brain tumor invasion. Magn Reson Med 52:994–1004, 2004. © 2004 Wiley‐Liss, Inc.
A robust policy for serial agile production systems
Authors: Iravani S.M.R. , Buzacott J.A. , Posner M.J.M.
Published: November 2004

One of the major problems in modeling production systems is how to treat the job arrival process. Restrictive assumptions such as Markovian arrivals do not represent real world systems, especially if the arrival process is generated by job departures from upstream workstations. Under these circumstances, cost‐effective policies that are robust with respect to the nature of the arrival process become of interest. In this paper, we focus on minimizing the expected total holding and setup costs in a two‐stage produce‐to‐order production system operated by a cross‐trained worker. We will show that if setup times are insignificant in comparison with processing times, then near‐optimal policies can be generated with very robust performances with respect to the arrival process. We also present conditions under which these near‐optimal policies can be obtained by using only the arrival and service rates. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005.
Single spin‐echo proton transverse relaxometry of iron‐loaded liver
Authors: St Pierre Timothy G. , Clark Paul R. , Chua‐anusorn Wanida
Published: November 2004

A single‐spin‐echo methodology is described for the measurement and imaging of proton transverse relaxation rates (R2) in iron‐loaded and normal human liver tissue in vivo. The methodology brings together previously reported techniques dealing with (i) the changes in gain between each spin‐echo acquisition, (ii) signal level offset due to background noise, (iii) estimation of signal intensities in decay curves at time zero to enable reliable extraction of relaxation times from tissues with very short T2 values, (iv) bi‐exponential modelling of decay curves with a small number of data points, and (v) reduction of respiratory motion artefacts. The accuracy of the technique is tested on aqueous manganese chloride solutions yielding a relaxivity of 74.1 ± 0.3 s−1 (mM)−1, consistent with previous reports. The precision of the in vivo measurement of mean liver R2 values is tested through duplicate measurements on 10 human subjects with mean liver R2 values ranging from 26 to 220 s−1. The random uncertainty on the measurement of mean liver R2 was found to be 7.7%. Copyright © 2004 John Wiley & Sons, Ltd.
First‐pass and equilibrium‐MRA of the aortoiliac region with a superparamagnetic iron oxide blood pool MR contrast agent (SH U 555 C): results of a human pilot study
Authors: Tombach Bernd , Reimer Peter , Bremer Christoph , Allkemper Thomas , Engelhardt Matthias , Mahler Marianne , Ebert Wolfgang , Heindel Walter
Published: November 2004

The purpose of this study was to study different doses for first‐pass and equilibrium phase MRA of aortoiliac vessels with a superparamagnetic iron oxide (SPIO) intravascular MR contrast agent (SH U 555 C) after single i.v. bolus injection. Sixteen healthy volunteers were prospectively enrolled into this single‐blind, placebo‐controlled clinical trial. SHU 555 C was injected as an i.v. bolus at stepwise increased dose levels of 5, 10, 20 and 40 μmol Fe/kg bodyweight (b.w.) corresponding to injection volumes of 0.01, 0.02, 0.04 and 0.08 ml/kg b.w. Serial high‐resolution three‐dimensional MRA of the aortoiliac vessels was acquired during first‐pass and equilibrium, at 6 min intervals up to 42 min after contrast application using a breath‐hold three‐dimensional FLASH sequence on a 1.5 T scanner. Intravascular enhancement was calculated within the abdominal aorta and the inferior vena cava and a statistical analysis for significant differences in vessel enhancement was performed during the bolus and equilibrium phases. The visibility of vessels was ranked and effects of potential artifacts on image quality were graded for each time point and dose group. SH U 555 C showed a dose‐dependent intravascular enhancement during the observation period (42 min). The highest dose of 40 μmol Fe/kg b.w. revealed the highest image quality during first‐pass and equilibrium phases. The intravascular enhancement in the aorta increased dose‐dependently from 5 to 40 μmol kg b.w. during first‐pass and equilibrium phases (p < 0.05). Intravascular signal inhomogeneities were observed at lower doses and decreased with increasing doses. First‐pass MRA was diagnostic at doses of 10, 20 and 40 μmol Fe/kg b.w. For equilibrium MRA, a dose of 40 μmol Fe/kg b.w. was considered to be diagnostic. SH U 555 C proved to be a contrast agent with a high T1‐effect suitable for both first‐pass MRA comparable to gadolinium‐enhanced MRA and high resolution equilibrium MRA up to 42 min post‐injection (p.i.). Copyright © 2004 John Wiley & Sons, Ltd.
High‐field magnetic resonance imaging of brain iron: birth of a biomarker?
Authors: Schenck John F. , Zimmerman Earl A.
Published: November 2004

The brain has an unusually high concentration of iron, which is distributed in an unusual pattern unlike that in any other organ. The physiological role of this iron and the reasons for this pattern of distribution are not yet understood. There is increasing evidence that several neurodegenerative diseases are associated with altered brain iron metabolism. Understanding these dysmetabolic conditions may provide important information for their diagnosis and treatment. For many years the iron distribution in the human brain could be studied effectively only under postmortem conditions. This situation was changed dramatically by the finding thatT2‐weighted MR imaging at high field strength (initially 1.5 T) appears to demonstrate the pattern of iron distribution in normal brains and that this imaging technique can detect changes in brain iron concentrations associated with disease states. Up to the present time this imaging capability has been utilized in many research applications but it has not yet been widely applied in the routine diagnosis and management of neurodegenerative disorders. However, recent advances in the basic science of brain iron metabolism, the clinical understanding of neurodegenerative diseases and in MRI technology, particularly in the availability of clinical scanners operating at the higher field strength of 3 T, suggest that iron‐dependent MR imaging may soon provide biomarkers capable of characterizing the presence and progression of important neurological disorders. Such biomarkers may be of crucial assistance in the development and utilization of effective new therapies for Alzheimer's and Parkinson's diseases, multiple sclerosis and other iron‐related CNS disorders which are difficult to diagnose and treat. Copyright © 2004 John Wiley & Sons, Ltd.
On the Convergence of Adaptive Finite Element Methods
Authors: Carstensen Carsten
Published: November 2004

State of the art simulations in computational mechanics aim reliability and efficiency via adaptive finite element methods (AFEMs) with a posteriori error control. The a priori convergence of finite element methods is justified by the density property of the sequence of finite element spaces which essentially assumes a quasi‐uniform mesh‐refining. The advantage is guaranteed convergence for a large class of data and solutions; the disadvantage is a global mesh refinement everywhere accompanied by large computational costs.

AFEMs automatically refine exclusively wherever the refinement indication suggests to do so and so violate the density property on purpose. Then, the a priori convergence of AFEMs is not guaranteed automatically and, in fact, crucially depends on algorithmic details. The advantage of AFEMs is a more effective mesh accompanied by smaller computational costs in many practical examples; the disadvantage is that the desirable error reduction property isnot alwaysguaranteed a priori. Efficient error estimators can justify a numerical approximation a posteriori and so achieve reliability. But it isnotclear from the start that the adaptive mesh‐refinement will generate an accurate solution at all.

This paper discusses particular versions of an AFEMs and their analyses for error reduction, energy reduction, and convergence results for linear and nonlinear problems. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Condition number of the stiffness matrix arising in POD Galerkin schemes for dynamical systems
Authors: Volkwein Stefan
Published: November 2004

Proper orthogonal decomposition (POD) provides a method for deriving low order models of non‐linear dynamical systems, where a so‐called POD basis is computed by a singular value decomposition and these basis functions are used in a Galerkin ansatz for the non‐linear dynamics. In this paper we prove estimates for the condition number of the stiffness matrices arising in the POD Galerkin discretization. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Curing behavior and toughening performance of epoxy resins containing hyperbranched polyester
Authors: Xu Gang , Shi Wenfang , Gong Ming , Yu Fei , Feng Jianping
Published: November 2004

The effects of the hyperbranched polyester with hydroxyl end groups (HBPE‐OH) on the curing behavior and toughening performance of a commercial epoxy resin (diglycidyl ether of bisphenol A, DGEBA) were presented. The addition of HBPE‐OH into DGEBA strongly increased its curing rate and conversion of epoxide group due to the catalytic effect of hydroxyl groups in HBPE‐OH and the low viscosity of the blend at curing temperature. The improvements on impact strength and critical stress intensity factor (or fracture toughness, K1c) were observed with adding HBPE‐OH. The impact strength was 8.04 kJ m−1 when HBPE‐OH reached 15 wt% and the K1c value was approximately two times the value of pure epoxy resin when HBPE‐OH content was 20 wt%. The morphology of the blends was also investigated, which indicated that HBPE‐OH particles, as a second phase in the epoxy matrix, combined with each other as the concentration of HBPE‐OH increased. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation and enhanced properties of poly(propylene)/ silica‐grafted‐hyperbranched polyester nanocomposites
Authors: Xu Nai , Zhou Wei , Shi Wenfang
Published: November 2004

A series of poly(propylene) silica‐grafted‐hyperbranched polyester nanocomposites by grafting the modified hyperbranched polyester (Boltorn™ H20), possessing theoretically 50% end carboxylic groups and 50% end hydroxyl groups, which endcapped with octadecyl isocyanate (C19), onto the surface of SiO2 particles (30 nm) through 3‐glycidoxy‐propyltrimethoxysilane (GPTS) was prepared. The effect of silica‐grafted‐modified Boltorn™ H20 on the mechanical properties of polypropylene (PP) was investigated by tensile and impact tests. The morphological structure of impact fracture surface and thermal behavior of the composites were determined by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The melt viscosity of composites was investigated by melt flow index (MFI). The obtained results showed that: (1) the modified Boltorn™ H20 was successfully grafted onto the SiO2 surface confirmed by FT‐IR and X‐ray photoelectron spectroscopy (XPS) analysis; (2) the incorporation of silica‐grafted‐modified Boltorn™ H20 (3–5 wt% SiO2) greatly enhanced the notched impact strength as well the tensile strength of the composites; (3) the incorporation of silica‐grafted‐modified Boltorn™ H20 had no influence on the melting temperature and crystallinity of PP phase; (4) the MFI of PP composites increased when the silica‐grafted‐modified Boltorn™ H20 particles were added compared with PP/SiO2 or PP/SiO2‐GPTS composites. Copyright © 2004 John Wiley & Sons, Ltd.
Effects of alkali post‐treatment on the particle morphology of soap‐free poly(methyl methacrylate‐ethyl acrylate‐acrylic acid) latices
Authors: Kang Kai , Kan Chengyou , Du Yi , Liu Deshan
Published: November 2004

Poly(methyl methacrylate‐ethyl acrylate‐acrylic acid) P(MMA‐EA‐AA) latices with narrow particle size distribution and “clean” particle surface were first synthesized by batch soap‐free emulsion polymerization, and the latex particles with anomalous morphology were obtained by alkali post‐treatment. Effects of treatment temperature and time, initial pH value, as well as 2‐butanone amount, on the morphology of latex particles were investigated. Results showed that anomalous structure of the dried latex particles could be easily identified using transmission electron microscopy (TEM) observation under the conditions of temperature >60°C, initial pH > 10.5 and 4.0–7.0 ml of 2‐butanone used. The higher the pH value is, the earlier the anomalous structure will occur. The volume expansion (ΔV) of the particle increased with the increase in treatment temperature and 2‐butanone amount. However, with the increase of initial pH value and treatment time,ΔVincreased first and then decreased, and different maximum ofΔVvalues were observed based on different conditions. Copyright © 2004 John Wiley & Sons, Ltd.
Lignocellulosic composite
Authors: El‐Meligy Magda G. , El‐Zawawy Waleed K. , Ibrahim Maha M.
Published: November 2004

Banana pseudostem fiber which is a lignocellulosic material, relatively inexpensive, and abundantly available was assessed in terms of its fiber‐matrix adhesion and dispersion in composites. Different types of adhesives were used. The mechanical and water absorption properties were investigated. Overall, for the produced composites, the incorporation of sawdust‐urea‐formaldehyde resin into prehydrolyzed banana fiber resulted in the best mechanical properties. Good adhesion‐fiber interaction is believed to be responsible for the good ultimate performance. The superior reinforcing characteristics of sawdust resin were shown by scanning electron microscopy (SEM), which revealed better fiber‐matrix adhesion. Water absorption tests revealed that the presence of the adhesives affected the amount of water absorbed. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation of hydrogel from green polymer
Authors: El‐Zawawy Waleed K.
Published: November 2004

A new method was used for the production of hydrogels from green polymer with a higher swelling ratio. These hydrogels were synthesized first by graft copolymerization between acrylamide (AM) and poly(vinyl alcohol) (PVA) with alkaline or kraft lignin (AM‐PVA‐g‐lignin) and then by mixing with acrylamide monomer. The kraft and alkaline lignins were isolated from pulping liquor and characterized using UV and FT‐IR spectroscopy, and the formed hydrogels were characterized using FT‐IR spectroscopy and scanning electron microscopy (SEM). Compared with kraft lignin hydrogel, the alkaline lignin hydrogel had very high swelling ratios and slower water uptake and deswelling rates attributed to its compatible network structure. The hydrogels formed were used also to study the influence of sodium chloride on the absorption capacity at room temperature and swelling ratios at different temperatures. Copyright © 2004 John Wiley & Sons, Ltd.
Astrocyte intermediate filaments in CNS pathologies and regeneration
Authors: Pekny Milos , Pekna Marcela
Published: November 2004

Astroglial cells are the most abundant cells in the mammalian central nervous system (CNS), yet our knowledge about their function in health and disease has been limited. This review focuses on the recent work addressing the function of intermediate filaments in astroglial cells under severe mechanical or osmotic stress, in hypoxia, and in brain and spinal cord injury. Recent data show that when astrocyte intermediate filaments are genetically ablated in mice, reactive gliosis is attenuated and the course of several CNS pathologies is altered, while the signs of CNS regeneration become more prominent. GFAP is the principal astrocyte intermediate filament protein and dominant mutations in the GFAP gene have been shown to lead to Alexander disease, a fatal neurodegenerative condition in humans. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Cilia‐related diseases
Authors: Afzelius BA
Published: November 2004

There are at least eight categories of cilia in the human body and malfunctioning of any one or several of them will have different consequences for the patient. A genetic error of the respiratory cilia (9 + 2) is the cause of the airways disease named immotile‐cilia syndrome (or PCD), whereas defective ependymal cilia (9 + 2) carries an increased risk of hydrocephalus. When the so‐called nodal cilia (9 + 0) of the early embryo are malfunctioning, there is a random determination of asymmetry of the heart and visceral organs (‘a 50% risk of situs inversus’). Some genes are responsible for the synthesis, transport, and assembly of the cilia, and mutations in these genes may lead to progressive degeneration of ciliary structures, such as the connecting cilium (9 + 0) of the photoreceptor cells—this is the cause of retinitis pigmentosa. Ciliary malfunctions due to genetic errors tend to be systemic and life‐long, whereas acquired diseases are local and may be temporary only. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Ifosfamide, carboplatin, and etoposide (ICE) reinduction chemotherapy in a large cohort of children and adolescents with recurrent/refractory sarcoma: The Children's Cancer Group (CCG) experience
Authors: Van Winkle Patrick , Angiolillo Anne , Krailo Mark , Cheung Ying‐Kuen , Anderson Barry , Davenport Virginia , Reaman Gregory , Cairo Mitchell S.
Published: November 2004

Background

The prognosis for children with recurrent/refractory sarcomas is poor. We determined the overall response rate (ORR) and overall survival (OS) of children with recurrent/refractory sarcomas who were given ifosfamide, carboplatin, and etoposide (ICE) in three Children's Cancer Group (CCG) phase I/II trials.

Procedure

Children with recurrent/refractory sarcoma were treated with ifosfamide (1,800 mg/m2/day on day 0–4), carboplatin (400 mg/m2/day on day 0–1), etoposide (100 mg/m2/day on day 0–4) and either rhG‐CSF (10 μg/kg/day vs. 5 μg/kg/day, CCG‐0894, 71 patients), PIXY321 (500–1,000 μg/m2/day, CCG‐0924, 14 patients), or rhG‐CSF (5 μg/kg/day) and IL‐6 (2.5–5 μg/kg/day, CCG‐0931, 12 patients).

Results

Ninety‐seven patients were evaluable for tumor response, 56 male and 41 female, median age 14.1 years (range 2.8–22.5 years). Tumor types were osteosarcoma (OTS) (n = 34), rhabdomyosarcoma (n = 27), Ewing sarcoma (EWS) (n = 21), soft tissue sarcoma‐not otherwise specified (n = 5), undifferentiated sarcoma (n = 6), fibrosarcoma (n = 2), peripheral primitive neuroectodermal tumor (n = 1), and extraosseous Ewing (n = 1). The ORR was 51% (27% complete response [CR]). OS at 1 and 2 years was 49% and 28%, respectively. Patients with CR or partial response (PR) had significantly increased 1‐ and 2‐year OS, 71% and 41%, respectively, (P < 0.001). Rhabdomyosarcoma patients with embryonal histology had significant improvement in 1‐ and 2‐year OS: 82% and 46%, respectively, compared with other histologies, (P < 0.005).

Conclusions

The ORR to ICE reinduction chemotherapy in children with recurrent/refractory sarcoma was 51%. OS of 1 and 2 years appeared significantly improved in patients who had CR or PR following ICE reinduction therapy or who had rhabdomyosarcoma with embryonal histology. © 2004 Wiley‐Liss, Inc.
Imatinib mesylate: An attractive alternative in young children with large, surgically challenging dermatofibrosarcoma protuberans
Authors: Price Victoria E. , Fletcher Jonathan A. , Zielenska Maria , Cole William , Viero Sandra , Manson David E. , Stuart Mary , Pappo Alberto S.
Published: November 2004

To document the clinical activity of imatinib mesyalte in a child with a dermatofibrosarcoma protuberans (DFSP). An 18‐month‐old girl presented with a large extremity DFSP. As surgical resection would have caused unacceptable functional defects, imatinib mesylate was administered to induce tumor reduction and or stabilization. After 23 weeks of therapy, magnetic resonance imaging (MRI) of the tumor showed a reduction in the subcutaneous thickness in the transverse plane. The drug was tolerated well without any adverse reactions. Imatinib mesylate offers a non‐surgical alternative for the treatment of large DFSP in children. © 2004 Wiley‐Liss, Inc.
Grantee relations: How can foundations and grantees be partners for sustained social change?
Authors: Walden Gwen I.
Published: November 2004

Changes in the nonprofit environment are forcing foundations and their grantees to reexamine their traditional relationships and pushing them to reach beyond well‐worn parameters to create new types of partnerships.
What foundations need to know and why
Authors: Culwell Alexa Cortes , Berkowitz Gale , Christen Ann M.
Published: November 2004

Foundations that develop specialized and sophisticated knowledge for developing, tracking, and sharing their program work are better positioned to fulfill their missions and steward resources in the service of genuine social change.
How a common language and consistent financial reporting practices could enhance the sector
Authors: Montgomery‐Talley La June , Richardson William C.
Published: November 2004

Every sector needs an effective mechanism for reporting to the public and to appropriate authorities that allows for clear understanding and oversight. The development of a common language and performance standards for private foundations is critical to improve transparency and accountability.
Biomoleküle in Bewegung: Proteindynamik
Authors: Parak Fritz G.
Published: November 2004

Viele Proteinmoleküle sind kleine Maschinen. Im Stillstand ist ihr Aufbau wohlbekannt. Doch wie sie arbeiten, ist meistens unklar. Die Grundlagen dieser Proteindynamik werden am Beispiel des Sauerstoffspeicher‐Proteins Myoglobin physikalisch untersucht. Dabei ist die Mößbauer‐Spektroskopie am Hämeisen besonders hilfreich. Während sich das Myoglobin bei sehr tiefen Temperaturen in einem festkörperähnlichen “Standby‐Modus” befindet, werden oberhalb einer charakteristischen Temperatur im Molekül proteinspezifische Bewegungsmoden aktiviert. Sie lassen sich als langsame, diffusionsartige Fluktuationen von Molekülsegmenten um die mittlere Struktur beschreiben. Diese Moden öffnen Kanäle in das Proteininnere, durch die Sauerstoffmoleküle zur Hämgruppe gelangen können. So ermöglichen sie Strukturänderungen, die für die biologische Funktion entscheidend sind.
A proteomic analysis of thioacetamide‐induced hepatotoxicity and cirrhosis in rat livers
Authors: Low Teck Yew , Leow Chon Kar , Salto‐Tellez Manuel , Chung Maxey C. M.
Published: November 2004

Thioacetamide (TAA) administration is an established technique for generating rat models of liver fibrosis and cirrhosis. Oxidative stress is believed to be involved as TAA‐induced liver fibrosis is initiated by thioacetamide S‐oxide, which is derived from the biotransformation of TAA by the microsomal flavine‐adenine dinucleotide (FAD)‐containing monooxygense (FMO) and cytochrome P450 systems. A two‐dimensional gel electrophoresis‐mass spectrometry approach was applied to analyze the protein profiles of livers of rats administered with sublethal doses of TAA for 3, 6 and 10 weeks respectively. With this approach, 59 protein spots whose expression levels changed significantly upon TAA administration were identified, including three novel proteins. These proteins were then sorted according to their common biochemical properties and functions, so that pathways involved in the pathogenesis of rat liver fibrosis due to TAA‐induced toxicity could be elucidated. As a result, it was found that TAA‐administration down‐regulated the enzymes of the primary metabolic pathways such as fatty acid β‐oxidation, branched chain amino acids and methionine breakdown. This phenomenon is suggestive of the depletion of succinyl‐CoA which affects heme and iron metabolism. Up‐regulated proteins, on the other hand, are related to oxidative stress and lipid peroxidation. Finally, these proteomics data and the data obtained from the scientific literature were integrated into an “overview model” for TAA‐induced liver cirrhosis. This model could now serve as a useful resource for researchers working in the same area.
Identification of protein‐protein interactions using in vivo cross‐linking and mass spectrometry
Authors: Vasilescu Julian , Guo Xuecui , Kast Juergen
Published: November 2004

The purification of protein complexes can be accomplished by different types of affinity chromatography. In a typical immunoaffinity experiment, protein complexes are captured from a cell lysate by an immobilized antibody that recognizes an epitope on one of the known components of the complex. After extensive washing to remove unspecifically bound proteins, the complexes are eluted and analyzed by mass spectrometry (MS). Transient complexes, which are characterized by high dissociation constants, are typically lost by this approach. In the present study, we describe a novel method for identifying transient protein‐protein interactions using in vivo cross‐linking and MS‐based protein identification. Live cells are treated with formaldehyde, which rapidly permeates the cell membrane and generates protein‐protein cross‐links. Proteins cross‐linked to a Myc‐tagged protein of interest are copurified by immunoaffinity chromatography and subjected to a procedure which dissociates the cross‐linked complexes. After separation by SDS‐PAGE, proteins are identified by tandem mass spectrometry. Application of this method enabled the identification of numerous proteins that copurified with a constitutively active form of M‐Ras (M‐RasQ71L). Among these, we identified the RasGAP‐related protein IQGAP1 to be a novel interaction partner of M‐RasQ71L. This method is applicable to many proteins and will aid in the study of protein‐protein interactions.
Establishment of a near‐standard two‐dimensional human urine proteomic map
Authors: Oh Jisun , Pyo Jae‐Hoon , Jo Eun‐Hyun , Hwang Sun‐Il , Kang Sun‐Chul , Jung Jae‐Hwan , Park Eui‐Kyun , Kim Shin‐Yoon , Choi Je‐Yong , Lim Jinkyu
Published: November 2004

A proteomic map for human urine on two‐dimensional (2‐D) gels has been developed. Initial studies demonstrated that the urine proteins prepared by conventional methods showed interference and poor reproducibility in 2‐D electrophoresis (2‐DE). To address this issue, urine samples were dialyzed to remove any interfering molecules. The dialysis of urine proteins and the concentration by lyophilization without fractionation significantly improved the reproducibility and resolution and likely represents the total urine proteins on a 2‐D gel. In addition, removing albumin from urine using Affi‐Gel Blue helped to identify the low‐abundant proteins. Using the developed method, we prepared proteins from urine collected from healthy females and males. The large inter‐ and intra‐subject variation in protein profiles on 2‐D gels made it difficult to establish a normal human urine proteomic 2‐D map. To resolve this problem, urinary proteins were prepared from the pooled urine collected from 20 healthy females and males, respectively. The established male and female urine proteomes separated on 2‐D gels were almost identical except for some potential sex‐dependent protein spots. We have annotated 113 different proteins on the 2‐D gel by peptide mass fingerprinting (PMF). We propose that the established total urine proteome can be used for 2‐DE analysis, liquid chromatography‐tandem mass spectrometry (LC‐MS/MS), and identification of novel disease‐specific biomarkers.
Psychrophilicity of Bacillus psychrosaccharolyticus: A proteomic study
Authors: Seo Jong Bok , Kim Hye Sook , Jung Gyoo Yeol , Nam Myung Hee , Chung Joo Hee , Kim Jin Young , Yoo Jong Shin , Kim Chan Wha , Kwon Ohoak
Published: November 2004

Psychrophilicity of Gram‐positive bacterium, Bacillus psychrosaccharolyticus was investigated in a proteomic approach. One hundred and thirty‐one protein spots were analyzed by electrospray ionization‐quadrupole‐time of flight‐tandem mass spectrometry and identified using an unpublished translated contig database as well as a nonredundant Gram‐positive bacteria protein database from NCBI because of the lack of a genome sequence of this organism. Results focused on proteomic behavior of cold‐response show that global up‐regulation of metabolic functions and protective mechanism by stress responses might play a major role in psychrophilicity of B. psychrosaccharolyticus.
Theoretical study of the thermal isomerization of isoxazole and 5‐methylisoxazole
Authors: Davico Gustavo E.
Published: November 2004

High‐level ab initio and semi‐empirical computations were carried out to investigate the mechanisms of thermal isomerization of isoxazole (1a) and 5‐methylisoxazole (2a). The calculations were made over the whole isomerization potential energy surface at the MP2/cc‐pVDZ and QCISD(T)/aug‐cc‐pVDZ//MP2/cc‐pVDZ levels. The predicted rate‐limiting transition states were refined further at the QCISD(T)/aug‐cc‐pVDZ//QCISD/cc‐pVDZ level. Ab initio results are in excellent agreement with available experimental results. Furthermore, they allow us to propose a detailed reaction mechanism and to exclude reaction paths proposed earlier. We also report the results from semi‐empirical computations. The MNDO method predicts reasonable values for the heat of formation of the reactants but it fails for other isomers and overestimates the activation energies for most reaction steps. The AM1 method yields improved values for the activation energies, at the expense of less reliable heats of formation for the minima in the potential energy surface. In general, both methods produce results that are good when the simplicity of the model is considered; however, there is no simple way to determine in advance when the results are meaningful. Thermochemical and kinetic parameters obtained by the different theoretical methods are discussed and compared with experimental values. Copyright © 2004 John Wiley & Sons, Ltd.
Hydrogen‐bonding‐aided synthesis of novel ladderlike organobridged polysiloxane containing side‐chain naphthyl groups
Authors: Sun Jin , Tang Huadong , Jiang Jinqiang , Zhou Xiaoshu , Xie Ping , Zhang Rongben , Fu Peng‐Fei
Published: November 2004

With a hydrogen‐bonding template, a novel soluble aryl amide‐bridged ladderlike polysiloxane, containing naphthyl as the side‐chain group, has been successfully synthesized via a stepwise coupling polymerization. It is proposed that the monomer, N,N′‐di(3‐naphthyldiethoxylsilyl‐propyl)‐[4,4′‐oxybis(benzyl amide)], prepared by Grignard and hydrosilylation reactions, undergoes self‐assembly first via amido hydrogen bonding and then via hydrolysis, followed by condensation under controlled reaction conditions to yield a high molecular weight, soluble, dark yellow polymer. The analytical results (Fourier transform infrared, 1H NMR, 29Si NMR, X‐ray diffraction, differential scanning calorimetry, and vapor pressure osmometry) show that the polymer possesses an ordered ladderlike architecture. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 636–644, 2003