bluuebunny/crossref_metadata_2025 huggingface dataset:
Rate‐independent behavior of ferromagnets
Authors: Kružík Martin
Published: November 2004

We review properties of a model allowing for rate‐independent evolution ofbulk ferromagnets. The model is based on Brown's micromagnetic theory specialized to a large‐body limit by DeSimone [2] which is enriched by a rate‐independent dissipative mechanism. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Portal hypertension develops in a subset of children with standard risk acute lymphoblastic leukemia treated with oral 6‐thioguanine during maintenance therapy
Authors: Broxson Emmett H. , Dole Mukund , Wong Raymond , Laya Bernard F. , Stork Linda
Published: November 2004

Background

6‐Thioguanine (TG) was recently studied to determine whether TG in maintenance therapy achieves better event free survival than 6‐mercaptopurine (MP) for standard risk acute lymphoblastic leukemia (ALL) on the clinical trial, CCG‐1952 (5/1996–1/2000). Veno‐occlusive disease was previously recognized as a complication of TG on CCG‐1952. We report a newly recognized pediatric complication of TG: splenomegaly and portal hypertension (PH) developing during maintenance or after completion of therapy.

Procedure

Twelve patients (3–10 years) had been randomized to receive a targeted dose of 50 mg/m2/day of TG during maintenance phases. Actual TG dose ranged from 25 to 77 mg/m2/day (median 34 mg/m2/day).

Results

The initial patient, a boy who had marked thrombocytopenia and intermittent splenomegaly during maintenance therapy, was evaluated for persistent pancytopenia and progressive splenomegaly 3 months after completion of therapy. Dilated splenic vein and collaterals consistent with PH were documented by MRI/MRA. Esophagogastroduodenoscopy found esophageal varices. Liver biopsy showed periportal fibrosis and marked dilatation of veins and venules. Of the other 12 patients, 9 patients studied had abnormal MRI/MRAs with evidence of varices in 4. Eight patients had splenomegaly on physical examination. Liver biopsies in a girl after 3.3 courses of TG and a boy after 4.6 courses of TG showed periportal fibrosis and dilatation of venules and sinusoids and minimal focal fatty changes. Subsequent MRI/MRAs have been stable or improved.

Conclusions

The evaluations of these 12 patients suggest that treatment with TG causes injury to the liver leading to PH and that thrombocytopenia and splenomegaly are clinical hallmarks of this toxicity. © 2004 Wiley‐Liss, Inc.
Prenatal diagnosis by rapid aneuploidy detection and karyotyping: a prospective study of the role of ultrasound in 1589 second‐trimester amniocenteses
Authors: Leung Wing Cheong , Waters Jonathan J. , Chitty Lyn
Published: November 2004

Background

Reliable methods are available for rapid aneuploidy detection (RAD) for the prenatal diagnosis of trisomies 21, 18 and 13. This study examines the potential advantages and limitations of using RAD as a replacement rather than as an adjunct to traditional karyotyping.

Methods

One thousand five hundred and eighty‐nine consecutive pregnancies referred for cytogenetic assessment were offered RAD (FISH or QF‐PCR) as an adjunct to traditional karyotyping. The results of these two processes were compared, and the effects of three policies for cytogenetic evaluation were determined: RAD alone, a combination of RAD for all and traditional karyotyping for cases with ultrasound anomalies or a policy of RAD and traditional karyotyping in all cases.

Results

RAD was uninformative because of maternal‐cell contamination in 37 (2.3%) cases compared to 4 (0.3%) cases of culture failure in traditional karyotyping. RAD and traditional karyotyping results were concordant in 1526 of 1548 (98.6%) cases. All non‐mosaic cases of trisomies 21, 18 and 13 and cases of triploidy were correctly identified by RAD, and there were no false‐positive diagnoses. The gold standard of a traditional karyotype in each case would have detected all chromosomal abnormalities. A policy of RAD alone would have identified 60 of 73 (82%) clinically important chromosomal abnormalities. The addition of a full karyotype for cases with evidence of ultrasound abnormalities would have improved detection to 95%.

Conclusion

A policy offering RAD to all patients, but restricting traditional karyotyping to cases with ultrasound anomalies, would reduce the number of traditional karyotypes requested by 70%, but maintain a 95% detection rate for all clinically important chromosomal abnormalities. Further studies are required to determine whether similar results could be obtained in district general hospital units and to determine whether this approach would be acceptable to health professionals and patients. Copyright © 2004 John Wiley & Sons, Ltd.
Prenatal ultrasound detection of bilateral focal polymicrogyria
Authors: Delle Urban Linei Augusta Brolini , Righini Andrea , Rustico Mariangela , Triulzi Fabio , Nicolini Umberto
Published: November 2004

Objectives

Prenatal diagnosis by ultrasound of fetal polymicrogyria has been reported only once.

Methods

We describe an additional case of polymicrogyria in a fetus from a monozygotic twin pair, probably the consequence of twin‐to‐twin transfusion syndrome.

Results

On ultrasound, there were bilateral cortical hyperechogenic spots, and prenatal magnetic resonance imaging demonstrated the typical features of bilateral focal polymicrogyria.

Conclusion

Polymicrogyria can be considered in the differential diagnosis of hyperechogenic brain lesions on fetal ultrasound. We also confirm the risk of brain damage in monochorionic twins pregnancies and the likely hypoxic–ischemic etiology of polymicrogyria. Copyright © 2004 John Wiley & Sons, Ltd.
Demonstration of cranial sutures and fontanelles at 15 to 16 weeks of gestation: a comparison between two‐dimensional and three‐dimensional ultrasonography
Authors: Ginath S. , Debby A. , Malinger G.
Published: November 2004

Objective

The purpose of this study was to evaluate the feasibility of obtaining good quality three‐dimensional ultrasound pictures of the cranial sutures and fontanelles and to compare between two‐dimensional and three‐dimensional ultrasound in identifying the normal appearance of cranial sutures and fontanelles by the transvaginal approach at 15 to 16 weeks of gestation.

Methods

Fifty fetuses were prospectively evaluated by two‐dimensional and three‐dimensional transvaginal sonography between 15 and 16 weeks of gestation. The sagittal, coronal, lambdoidal, and metopic sutures, as well as anterior and posterior fontanelles, were inspected.

Results

Three‐dimensional ultrasound enabled visualization of all sutures in 37 (74%) fetuses compared to 28 (56%) fetuses examined by two‐dimensional ultrasonography (p = NS). The visualization of the sagittal suture was significantly superior by three‐dimensional ultrasonography compared to two‐dimensional ultrasonography (50 (100%) vs 35 (70%), p < 0.001). No significant difference between the two modalities was found in visualization of the fontanelles.

Conclusion

Sutures and fontanelles are usually satisfactorily demonstrated by two‐dimensional and three‐dimensional ultrasound at 15 to 16 weeks of gestation. The sagittal suture is difficult to visualize using two‐dimensional ultrasound, and three‐dimensional ultrasound appears to be the best method for its demonstration. Copyright © 2004 John Wiley & Sons, Ltd.
A rare case of de novo distal 19q trisomy prenatally diagnosed
Authors: Rombout Sonia , Sartenaer Daniel , Parmentier Benoît , Dugauquier Christian , Gillerot Yves
Published: November 2004

We present a case of de novo trisomy of distal 19q diagnosed prenatally by cytogenetics and FISH analysis. The autopsy performed after termination of the pregnancy showed major internal and external malformations that are associated with this chromosome abnormality. Copyright © 2004 John Wiley & Sons, Ltd.
SHORT COMMUNICATION: ACCELERATED PUBLICATION: Multicrystalline silicon solar cells exceeding 20% efficiency
Authors: Schultz O. , Glunz S. W. , Willeke G. P.
Published: November 2004

This paper presents the first conversion efficiency above 20% for a multicrystalline silicon solar cell. The application of wet oxidation for rear surface passivation significantly reduces the process temperature and therefore prevents the degradation of minority‐carrier lifetime. The excellent optical properties of the dielectrically passivated rear surface in combination with a plasma textured front surface result in a superior light trapping and allow the use of substrates below 100 μm thickness. A simplified process scheme with laser‐fired rear contacts leads to conversion efficiencies of 20·3% for multicrystalline and 21·2% for monocrystalline silicon solar cells on small device areas (1 cm2). Copyright © 2004 John Wiley & Sons, Ltd.
Utilization of a new biotinylation reagent in the development of a nondiscriminatory investigative approach for the study of cell surface proteins
Authors: Gauthier Daniel J. , Gibbs Bernard F. , Rabah Nadia , Lazure Claude
Published: November 2004

In order to circumvent the various problems encountered during the study of membrane‐bound proteins, we designed and synthesized a novel membrane‐impermeable biotinylation reagent incorporating chemical properties compatible with this goal. We then developed a nondiscriminatory analytical procedure for such studies which overcomes possible selectivity, contamination and solubility problems. The necessary steps (labeling, limited in situ proteolysis, affinity purification) are all conducted in mild or near native conditions. This versatile method could provide an accurate picture of the cell surface proteome.
Quantitative protein profiling using antibody arrays
Authors: Barry Richard , Soloviev Mikhail
Published: November 2004

Traditional approaches to microarrays rely on direct binding assays where the extent of hybrid‐isation and the signal detected are a measure of the analyte concentration in the experimental sample. This approach, directly imported from the nucleic acid field, may fail if applied to antibody‐antigen interactions due to the shortage of characterised antibodies, the significant heterogeneity of antibody affinities, their dependence on the extent of protein modification during labelling and the inherent antibody cross‐reactivity. These problems can potentially limit the multiplexing capabilities of protein affinity assays and in many cases rule out quantitative protein profiling using antibody microarrays. A number of approaches aimed at achieving quantitative protein profiling in a multiplex format have been reported recently. Of those reported, the three most promising routes include signal amplification, multicolour detection and competitive displacement approaches to multiplex affinity assays. One in particular, competitive displacement, also overcomes the problems associated with quantitation of affinity interactions and provides the most generic approach to highly parallel affinity assays, including antibody arrays.
Proteome analysis of human substantia nigra in Parkinson's disease
Authors: Basso Manuela , Giraudo Sabrina , Corpillo Davide , Bergamasco Bruno , Lopiano Leonardo , Fasano Mauro
Published: November 2004

Protein expression has been compared in human substantia nigra specimens from Parkinson's disease (PD) patients and from controls, and 44 proteins expressed in this midbrain region were identified by peptide mass fingerprinting. Among them, nine showed changes in their abundance. L and M neurofilament chains are less abundant in PD specimens, whereas peroxiredoxin II, mitochondrial complex III, ATP synthase D chain, complexin I, profilin, L‐type calcium channel δ‐subunit, and fatty‐acid binding protein are significantly more present in PD samples than in controls. Besides the consolidated view of oxidative stress involvement in PD pathogenesis, suggested by overexpression of mitochondrial and reactive oxygen species (ROS)‐scavenging proteins, these results indicate a possible potentiation mechanism of afferent signals to substantia nigra following degeneration of dopaminergic neurons.
Challenges in mass spectrometry‐based proteomics
Authors: Reinders Joerg , Lewandrowski Urs , Moebius Jan , Wagner Yvonne , Sickmann Albert
Published: November 2004

During the last decade, protein analysis and proteomics have been established as new tools for understanding various biological problems. As the identification of proteins after classical separation techniques, such as two‐dimensional gel electrophoresis, have become standard methods, new challenges arise in the field of proteomics. The development of “functional proteomics” combines functional characterization, like regulation, localization and modification, with the identification of proteins for deeper insight into cellular functions. Therefore, different mass spectrometric techniques for the analysis of post‐translational modifications, such as phosphorylation and glycosylation, have been established as well as isolation and separation methods for the analysis of highly complex samples, e.g. protein complexes or cell organelles. Furthermore, quantification of protein levels within cells is becoming a focus of interest as mass spectrometric methods for relative or even absolute quantification have currently not been available.

Protein or genome databases have been an essential part of protein identification up to now. Thus, de novo sequencing offers new possibilities in protein analytical studies of organisms not yet completely sequenced.

The intention of this review is to provide a short overview about the current capabilities of protein analysis when addressing various biological problems.
Increases in leukocyte cluster of differentiation antigen expression during cardiopulmonary bypass in patients undergoing heart transplantation (vol. 4, Issue 7, pp. 1918‐1926)
Authors: Lal Sean , Lui Rodney , Nguyen Lisa , Macdonald Peter , Denyer Gareth , dos Remedios Cristobal
Published: November 2004

See original http://dx.doi.org/10.1002/pmic.200300756
Block copolymers of acrylic acid and butyl acrylate prepared by reversible addition–fragmentation chain transfer polymerization: Synthesis, characterization, and use in emulsion polymerization
Authors: Gaillard Nicolas , Guyot Alain , Claverie Jerome
Published: November 2004

Amphiphilic block copolymers of poly(acrylic acid‐b‐butyl acrylate) were prepared by reversible addition–fragmentation chain transfer polymerization in a one‐pot reaction. These copolymers were characterized by NMR, static and dynamic light scattering, tensiometry, and size exclusion chromatography. The aggregation characteristics of the copolymers corresponded to those theoretically predicted for a star micelle. In a butyl acrylate and methyl methacrylate emulsion polymerization, low amounts of these copolymers could stabilize latices with solid contents up to 50%. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 684–698, 2003
Real‐time Fourier transform infrared study of free‐radical UV‐induced polymerization of hybrid sol–gel. I. Effect of silicate backbone on photopolymerization kinetics
Authors: Soppera O. , Croutxé‐Barghorn C.
Published: November 2004

Free‐radical photocurable hybrid sol–gel materials have gained special interest. They are becoming more and more widely used for applications in coatings, optics, sensors, catalysis, and so forth. The photochemical step is a fundamental step in the elaboration of this kind of hybrid sol–gel. However, little is known about the specifics of the photochemistry in this material. The relation between the organic and the inorganic part is investigated. Hydrolysis and condensation reactions were characterized by 29Si NMR. A precise description of the material before irradiation is of paramount importance to understand photoinduced phenomena. Real‐time Fourier transform infrared spectroscopy was used to examine the photopolymerization of hybrid sol–gel under UV irradiation. UV photopolymerization occurred efficiently in hybrid sol–gel although inhibition of free‐radical polymerization by molecular oxygen was pronounced. Important structural modifications during irradiation were also measured. They concern both inorganic and organic parts of the hybrid material. The condensation state of the silicate network was of crucial importance. The presence of the silicate backbone did not limit the final conversion ratio. On the contrary, photopolymerization occurred more efficiently for systems with a higher degree of condensation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 716–724, 2003
Synthesis and thermal behavior of phenylethynyl‐terminated linear and hyperbranched polyphenylquinoxalines
Authors: Baek Jong‐Beom , Harris Frank W.
Published: November 2004

A phenylquinoxaline (PQ) AB monomer mixture was treated with monofunctional and difunctional end‐capping agents and with and without a coupling agent to afford phenylethynyl‐terminated linear PQ oligomers. The resulting PQ oligomers were soluble in common organic solvents and had intrinsic viscosities (IVs) of 0.21–0.30 dL/g. The glass‐transition temperature (Tg) of the diphenylethynyl‐end‐capped PQ oligomer on both sides increased the most, from 215 °C (before curing) to 251 °C (after curing). The PQ AB2 monomer, which acted as both a coupling agent and a monomer for the hyperbranched polymer, was treated with an AB monomer and end‐capping agents to afford phenylethynyl‐terminated hyperbranched polyphenylquinoxalines (PPQs). They were also soluble in common organic solvents, had IVs of 1.00–1.65 dL/g and Tg's of 251–253 °C, and underwent exothermic cure with maxima around 412–442 °C. The Tg's of the cured hyperbranched PPQs ranged from 258 to 261 °C, depending on the number of phenylethynyl groups on the surface. After further curing, they displayed a Tg of 316 °C in one sample and turned into a fully crosslinked network. The dynamic melt viscosities of a linear oligomer (IV = 0.21 dL/g), a hyperbranched sample (IV = 1.00 dL/g), and a linear reference PPQ (IV = 1.29 dL/g) were compared with respect to the processing temperature. The PQ oligomer and hyperbranched PPQ had low melt viscosities. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6318–6330, 2004
Thianthrene as an activating group for the synthesis of poly(aryl ether thianthrene)s by nucleophilic aromatic substitution
Authors: Edson Joseph B. , Knauss Daniel M.
Published: November 2004

A method for the preparation of poly(aryl ether thianthrene)s has been developed in which the aryl ether linkage is generated in the polymer‐forming reaction. The thianthrene heterocycle is sufficiently electron‐withdrawing to allow fluoro displacement with phenoxides by nucleophilic aromatic substitution. The monomer for this reaction, 2,7‐difluorothianthrene, can be synthesized in a moderate yield by a simple reaction sequence. Semiempirical calculations at the PM3 level suggest that 2,7‐difluorothianthrene is sufficiently activated, whereas NMR spectroscopy (1H and 13C) indicates that the monomer is only slightly activated or (19F) not sufficiently activated for nucleophilic aromatic substitution. Model reactions with p‐cresol have demonstrated that the fluorine atoms on 2,7‐difluorothianthrene are readily displaced by phenoxides in high yields, and the process has been deemed suitable for polymer‐forming reactions. High‐molecular‐weight polymers have been produced from bisphenol A, bisphenol AF, and 4,4′‐biphenol. The polymers have been characterized with gel permeation chromatography, NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The glass‐transition temperatures for the polymers of different compositions and molecular weights range from 138 to 181 °C, and all the polymers have shown high thermooxidative stability, with 5% weight loss values in an air environment approaching 500 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6353–6363, 2004
Controlled polymerization of N‐isopropylacrylamide with an activated methacrylic ester
Authors: Savariar Elamprakash N. , Thayumanavan S.
Published: November 2004

A copolymer of N‐isopropylacrylamide with the N‐hydroxysuccinimide ester of methacrylic acid has found use in a variety of applications. Here we report our efforts to gain control over the molecular weight distribution of this copolymer with controlled radical polymerization methods, such as atom transfer radical polymerization, reversible addition–fragmentation transfer (RAFT), and nitroxide‐mediated polymerization. We have found that RAFT is capable of affording these copolymers with a polydispersity index of 1.1–1.2. Our results for all three polymerizations are reported. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6340–6345, 2004
Brominated poly(isobutylene‐co‐para‐methylstyrene) (BIMS)‐clay nanocomposites: Synthesis and characterization
Authors: Maiti Madhuchhanda , Sadhu Susmita , Bhowmick Anil K.
Published: November 2004

In this work, preparation and properties of different nanoclays modified by organic amines (octadecyl amine, a primary amine, and hexadecyltrimethylammonium bromide, a tertiary amine) and brominated polyisobutylene‐co‐paramethylstyrene (BIMS)‐clay nanocomposites are reported. The clays and the rubber nanocomposites have been characterized with the help of Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X‐ray diffraction (XRD). The X‐ray diffraction peaks observed in the range of 3 °–10 ° for the modified clays disappear in the rubber nanocomposites. TEM photographs show predominantly exfoliation of the clays in the range of 12 ± 4 nm in the BIMS. In the FTIR spectra of the nanocomposites, there are common peaks of virgin rubber as well as those of the clays. Excellent improvement in mechanical properties like tensile strength, elongation at break, and modulus is observed on incorporation of the nanoclays in the BIMS. Structure‐property correlation in the above nanocomposites is attempted. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4489–4502, 2004
Poly(methyl silsesquioxane)/amphiphilic block copolymer hybrids and their porous derivatives: Poly(styrene‐block‐acrylic acid) and poly(styrene‐block‐3‐trimethoxysilylpropyl methacrylate)
Authors: Chang Yung , Chen Ching‐Yi , Chen Wen‐Chang
Published: November 2004

Porous poly(methyl silsesquioxane) (PMSSQ) films were prepared from PMSSQ/amphiphilic block copolymer (ABC) hybrids, and this was followed by spin coating and multistep baking. The ABCs were poly(styrene‐block‐acrylic acid) (PS‐b‐PAA) and poly(styrene‐block‐3‐trimethoxysilylpropyl methacrylate) (PS‐b‐PMSMA), which were synthesized by living polymerization. The chemical bonding between the ABCs and PMSSQ resulted in significant differences in the morphologies and properties of the hybrids and their porous derivatives. Both intramolecular and intermolecular hydrogen bonding existed in the PMSSQ/PS‐b‐PAA hybrid and led to macrophase separation. Through the modification of the chemical structure from the poly(acrylic acid) segment to PMSMA, covalent bonding between PMSSQ and PMSMA occurred and prevented the macrophase separation and initial pyrolysis of the ABC. Modulated differential scanning calorimetry results also suggested a significant difference in the miscibility of the two hybrid systems. The chemical bonding resulted in higher retardation of the symmetry‐to‐nonsymmetry SiOSi structural transformation for PMSSQ/PS‐b‐PMSMA than for PMSSQ/PS‐b‐PAA according to Fourier transform infrared studies. The pore size of the nanoporous thin film from the PMSSQ/PS‐b‐PMSMA hybrid was estimated by transmission electron microscopy to be less than 15 nm. The refractive index and dielectric constant of the prepared porous films decreased from 1.354 to 1.226 and from 2.603 to 1.843 as the PS‐b‐PMSMA loading increased from 0 to 50 wt %, respectively. This study suggests that chemical bonding in hybrid materials plays a significant role in the preparation of low‐dielectric‐constant nanoporous films. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4466–4477, 2004
Evaluating relief valve reliability when extending the test and maintenance interval
Authors: Urbanik Stanley A.
Published: November 2004

Presently, more and more programs appear that provide processes for evaluating and extending the time between major process shutdowns and maintenance. RBI (risk‐based inspections) and Six Sigma processes are two examples of methods currently in use to help drive shutdown extension programs. The relief valves on these processes often go along with the shutdown extension programs without a thorough understanding of the impact on relief valve reliability. Using an analysis for a “stand‐by system,” the change in PFD (probability of failure on demand) of the relief system as a function of change in test interval is shown. Human error is another factor that compromises relief valve reliability. Some arguments are offered that suggest reduced inspections increase reliability because there are fewer opportunities for human error. This study addresses the human error question and shows that the human error contribution is constant while the relief valve is in service. Finally, the increase in PFD when increasing the test interval is discussed in terms of the potential increase in risk. The increased risk as a percentage change should be communicated and understood by those deciding to extend shutdown intervals. © 2004 American Institute of Chemical Engineers Process Saf Prog 23: 191–196, 2004
Protection Survivability Importance in Systems with Multilevel Protection
Authors: Levitin Gregory
Published: November 2004

This paper considers systems that can have different states corresponding to different combinations of available elements constituting the system. Each state can be characterized by a performance rate, which is the quantitative measure of a system's ability to perform its task. Both the impact of external factors (attack) and internal causes (failures) affect system survivability, which is determined as the probability of meeting a given demand. In order to increase the system's survivability a multilevel protection is applied to its subsystems. This means that a subsystem and its inner level of protection are in turn protected by the protection of an outer level. This double‐protected subsystem has its outer protection and so forth. In such systems, the protected subsystems can be destroyed only if all of the levels of their protection are destroyed. Each level of protection can be destroyed only if all of the outer levels of protection are destroyed. In such systems, different protections play different roles in providing for the system's survivability. The evaluation of the relative influence of the protections' survivability on the survivability of the entire system provides useful information about the importance of these protections. The protection survivability importance index is introduced in order to evaluate this influence and an algorithm for evaluating the index is presented. The relevancy of protection is also considered. Illustrative examples are presented. Copyright © 2004 John Wiley & Sons, Ltd.
Calculation of some Reliability Measures for Redundancy Systems with Different Types of Failures
Authors: Rosenhaus M. B. , Zarudny V. I.
Published: November 2004

The methods developed to determine some reliability measures such as mean operating time to failure, the reliability and availability functions of duplicated systems with n types of failures are discussed. These methods enable the reliability measures to be obtained directly from the state graph without solving a system of algebraic or differential equations. Copyright © 2004 John Wiley & Sons, Ltd.
Reliability Model for Polyimide–Metal Interconnect Shorts in GaAs ASICs
Authors: Strifas N. , Yalamanchili P. , Christou A.
Published: November 2004

A physical reliability model has been developed to calculate the time to failure of polyimide–metal multilevel interconnected GaAs components due to the shorts between interconnect metallizations through a polyimide interlayer. The failure mechanism for the shorts between neighboring metals through the polyimide is described as a stress‐assisted diffusion process along a polyimide microcrack due to the combination of process defect and high thermal stress concentration. The finite element method has been used to determine the temperature increase during operation and the resulting thermal stress due to the difference in coefficients of thermal expansion (CTEs) of the materials used in the multilevel metallization GaAs module of devices. Numerical methods have been used to solve the partial differential diffusion equations with stress gradients in order to obtain the time to failure of the devices. The time to failure for the shorts between metal level 4 and metal 2 at 123 °C operating temperature was calculated to be 20 h for the conditions analyzed. The activation energy for the failure of the shorts between two level metals was calculated to be 0.48 eV. Copyright © 2004 John Wiley & Sons, Ltd.
A Petri Net Approach to Remote Diagnosis for Failures of Cardiac Pacemakers
Authors: Yang S. K.
Published: November 2004

This paper describes the application of Petri nets to remote diagnosis for failures of cardiac pacemakers. The operations, structures and basic control methods of the different types of cardiac pacemakers are first described. A combined synchronous pacemaker is modeled into a Petri net in this study. Twelve checkpoints are added into the modeled Petri net so as to construct a Petri net for failure diagnosis. A remote mode for failure diagnosis of implanted pacemakers is also designed by the Petri net approach. A low‐power transmitter transmits a checking‐code with 12 digits from the implanted pacemaker to the outside of the patient's body manually or automatically. By observing the markings of the checking code, the working status and the health condition of the pacemaker are clear at a glance. Applications of the Petri net method for failure diagnosis and control optimization are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
A Convenient Solid Phase Synthesis of Disubstituted Guanidines
Authors: Sandanayake Saman , Perera Senake , Ede Nicholas J.
Published: November 2004

TMI‐isocyanate SynPhaseTM lanterns have been used in the convenient synthesis of a disubstituted guanidine library. Support‐bound isocyanate was reacted with primary amines and the resulting urea derivatives were dehydrated to yield the corresponding support‐bound carbodiimides. The carbodiimides were reacted with primary, secondary or anilinic amines to form the corresponding guanidines. Convenient traceless cleavage of the products from the solid phase with 25% TFA/DCM gave the corresponding guanidines in good yield and good to excellent purity.
High Capacity Poly(ethylene glycol) Based Amino Polymers for Peptide and Organic Synthesis
Authors: Roice Michael , Johannsen Ib , Meldal Morten
Published: November 2004

A beaded, chemically stable, high capacity amino resin for solid phase synthesis under polar and non‐polar conditions is described. By exhaustive reduction of amide carbonyl groups in PEG cross linked poly(ethylene glycol)‐poly(acrylamide) copolymer (PEGA) a significant increase in functional amino groups is obtained. Furthermore, a resin containing 90% PEG which is free of amide carbonyl groups is produced. The polymer was characterized by IR spectroscopy and the macroscopic properties of the beads were analyzed by microscopy. Excellent swelling properties in various solvents ranging from water to DCM were demonstrated. The chemical stability of the polymer in various reagents and solvents was investigated and changes in resin properties monitored by IR spectroscopy. The mechanical stability of the resin was analyzed by measurement of compressive strain. The unique three dimensional structure of the swelled polyethylene glycol network facilitate fast and unhindered diffusion of reagents and the support is excellent for synthesis of peptides or peptide mimetics, which can be produced in high yield/reaction volume. The efficacy of the new resin in solid phase synthesis was demonstrated by synthesizing an α‐MSH peptide fragment. A cyclic peptide mimetic was also synthesized on the new resin by the Cu (1) catalyzed intra molecular cyclo addition of alkyne and azide to form a triazole acting as a disulphide mimetic entity in very high yield and purity.
QSAR Analysis of 2,3‐Diaryl Benzopyrans/Pyrans as Selective COX‐2 Inhibitors Based on Semiempirical AM1 Calculations
Authors: Prasanna Sivaprakasam , Manivannan Elangovan , Chaturvedi Subash Chandra
Published: November 2004

Quantitative structure‐activity relationship (QSAR) analysis was performed on a combined series of 2,3 diaryl benzopyrans and pyrans for their cyclooxygenase‐2 (COX‐2) inhibition. QSAR investigations based on semiempirical, Austin Model‐1 (AM1) calculations reveal that electronic and hydophobic interactions are primarily responsible for COX‐2 enzyme‐ligand interaction. The derived QSAR model aided by residual analysis demonstrated that the COX‐2 inhibitory activity is highly correlated with the electronic descriptors, lowest unoccupied molecular orbital (ELUMO), Dipole‐Z and hydrophobicity of the molecules. The conclusion can be drawn that more hydrophobic, electron‐withdrawing substituents at 3rd aromatic ring of the lead structure improves activity. The lesser the Z component the ligand has, the more correct its orientation towards the COX‐2 binding site. The derived QSAR model shows good internal (exemplified through leave one out‐q2=0.786) and external (r$\rm{ {_{pred}^{2}}}$=0.5737) predictive ability for a test set and can be used in designing better selective COX‐2 inhibitors among these congeners in future.
Prediction of Carbonic Anhydrase Activation by Tri‐/Tetrasubstituted‐pyridinium‐azole Compounds: A Computational Approach Using Novel Topochemical Descriptor
Authors: Bajaj Sanjay , Sambi S. S. , Madan A. K.
Published: November 2004

See original QSAR Comb. Sci. 2004, 23, 506–514
Slater's nonlocal exchange potential and beyond
Authors: Howard I. A. , March N. H.
Published: November 2004

The local density approximation (LDA) to the exchange potential Vx(r), namely the ρ1/3 electron gas form, was already transcended in Slater's 1951 paper. Here, using Dirac's 1930 form for the exchange energy density ϵx(r), the Slater (Sl) nonlocal exchange potential V(r) is defined by 2ϵx(r)/ρ(r). In spherical atomic ions, say the Be or Ne‐like series, this form V(r) already has the correct behavior in both r → 0 and r → ∞ limits when known properties of the exchange energy density ϵx(r) and the ground‐state electron density ρ(r) are invoked. As examples, some emphasis will first be given to the use of the so‐called 1/Z expansion in such spherical atomic ions, for which analytic results can be obtained for both ϵx(r) and ρ(r) as the atomic number Z becomes large. The usefulness of the 1/Z expansion is directly demonstrated for the U atomic ion with 18 electrons by comparison with the optimized effective potential prediction. A rather general integral equation for the exchange potential is then proposed. Finally, without appeal to large Z, two‐level systems are considered, with specific reference to the Be atom and to the LiH molecule. In all cases treated, the Slater potential V(r) is a valuable starting point, even though it needs appreciable quantitative corrections reflecting directly atomic shell structure. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
UV laser ablation of GdCa4O(BO3)3 (GdCOB) investigated by Fourier transform ion cyclotron resonance mass spectrometry
Authors: Chéty‐Gimondo Rachel , Aubriet Frédéric , Millon Eric , Muller J.‐F.
Published: November 2004

The ions generated by laser ablation (LA) of calcium and gadolinium oxoborate GdCa4O(BO3)3 (GdCOB) were investigated by Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS), a powerful tool for the characterization of ionic species produced by laser interaction with solid material. In order to better understand the matter transfer and the mechanism of thin film growth by pulsed‐laser deposition (PLD), cationic and anionic clusters generated by UV laser ablation of GdCOB bulk material were studied. Laser ablation of GdCOB leads to the formation of various cluster ions which result from association of CaO, BO and B2O3 building blocks (BB) with different charge carriers (CC): H+, BO+, GdO+ in positive ion mode, and BO, OK−, OH−, Cl−, WO in negative ion mode. LA‐FTICRMS investigations allow us to assign a valence state to each metallic atom included in each BB. A +II chemical state may be associated with calcium and +II and +III ones to boron. UV laser ablation of GdCOB therefore induces reduction processes of boron species in the gas phase. The oxygen reactive atmosphere used during PLD experiments allows the growth of stoichiometric thin films by fixation of oxygen on the ablated species. Copyright © 2004 John Wiley & Sons, Ltd.
Migratory patterns and return to the catch site of adult brown trout (Salmo trutta L.) in a regulated river
Authors: Arnekleiv Jo Vegar , Rønning Lars
Published: November 2004

The spawning migration and local homing of adult brown trout was analysed using radio telemetry in a regulated river in central Norway. Twenty‐eight large (37–64 cm) brown trout (Salmo trutta L.) were tracked before, during and after spawning in the River Nea, a watercourse with several obstructions, including an outlet tunnel from a power station and a regulated stretch (26 km) with 45 weirs.

Two major patterns of spawning migration were found: (1) about half (n = 16; 57%) of the trout moved very little and remained in the deeper pools of the river from June until November; (2) about half (n = 12; 43%) of the trout migrated relatively long distances (12.5–28 km) up the river prior to the spawning period where they stayed in the outlets of small tributaries, or in rapids on the main river during the spawning period. We assume that these trout belong to a population of lake‐run migratory trout using the River Nea for spawning.

There was no significant difference in body length of migratory and stationary brown trout and no significant difference in total distance moved by migratory males (30.5 km, n = 6) and females (20.5 km, n = 6, p > 0.05). Among migratory trout, we found no correlation between body length and migrated distance. Of the 12 migratory trout, nine undertook fast upward migration in periods of high water flow (> 100 m3/s). They passed the outlet tunnel from the power station and negotiated two to 35 weirs before reaching their main reproduction areas. Three trout crossed several weirs when the discharge was low (10–40 m3/s). When there was low discharge, fish remained at the outlet tunnel for up to four weeks and showed a high level of activity. Postspawning downstream migration started between 25 September and 25 October. Most migratory trout (n = 9) wintered in pools on the lower part of the river or in weir basins; only two trout descended to the lake (Selbusjøen) in late autumn. Copyright © 2004 John Wiley & Sons, Ltd.
Case‐sibling gene‐association studies for diseases with variable age at onset
Authors: Kraft Peter , Thomas Duncan C.
Published: November 2004

Studies which compare cases to disease‐free siblings are useful for assessing association between a genetic locus and a phenotypic trait, as they eliminate the possibility of confounding by population stratification. Many analytic methods for such family‐based studies are based on a binary disease model. However, complex diseases have variable age at onset. Consequently, binary‐outcome methods can be inefficient or biased. We review methods for analysing censored age‐at‐onset data from family studies, including stratified Cox regression and genotype‐decomposition regression, an unstratified procedure which regresses age‐at‐onset on between‐ and within‐family genotype components. We also introduce a retrospective likelihood for censored age‐at‐onset data, which requires an external estimate of the baseline hazard. Stratified Cox regression does not use controls who have not attained the age of their case sibling(s), potentially leading to a loss of efficiency. Both genotype‐decomposition regression and the retrospective likelihood use these younger controls. We assess the performance of these methods via simulation studies. Stratified Cox regression and the retrospective likelihood have appropriate type I error rates in almost all situations studied; genotype‐decomposition regression is often anti‐conservative. Away from the null, confidence intervals for the relative risk derived from stratified Cox regression are anti‐conservative when the disease is rare and case‐rich families are sampled. The retrospective likelihood is more efficient than stratified Cox regression and its confidence intervals have correct coverage when the disease is rare or the estimate of the baseline hazard is reasonably accurate. These results suggest that when estimating genotype relative risks is the principal analytic goal, stratified Cox regression is appropriate as long as the disease is common; when the disease is rare, the retrospective likelihood may be more appropriate. Copyright © 2004 John Wiley & Sons, Ltd.
Ordered multiple‐class ROC analysis with continuous measurements
Authors: Nakas Christos T. , Yiannoutsos Constantin T.
Published: November 2004

Receiver operating characteristic (ROC) curves have been useful in two‐group classification problems. In three‐ and multiple‐class diagnostic problems, an ROC surface or hyper‐surface can be constructed. The volume under these surfaces can be used for inference using bootstrap techniques or U‐statistics theory. In this article, ROC surfaces and hyper‐surfaces are defined and their behaviour and utility in multi‐group classification problems is investigated. The formulation of the problem is equivalent to what has previously been proposed in the general multi‐category classification problem but the definition of ROC surfaces here is less complex and addresses directly the narrower problem of ordered categories in the three‐class and, by extension, the multi‐class problem applied to continuous and ordinal data. Non‐parametric manipulation of both continuous and discrete test data and comparison between two diagnostic tests applied to the same subjects are considered. A three‐group classification example in the context of HIV neurological disease is presented and the results are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
The interpoint distance distribution as a descriptor of point patterns, with an application to spatial disease clustering
Authors: Bonetti Marco , Pagano Marcello
Published: November 2004

The topic of this paper is the distribution of the distance between two points distributed independently in space. We illustrate the use of this interpoint distance distribution to describe the characteristics of a set of points within some fixed region. The properties of its sample version, and thus the inference about this function, are discussed both in the discrete and in the continuous setting. We illustrate its use in the detection of spatial clustering by application to a well‐known leukaemia data set, and report on the results of a simulation experiment designed to study the power characteristics of the methods within that study region and in an artificial homogenous setting. Copyright © 2004 John Wiley & Sons, Ltd.
Chronic disease prevention: public health potential and research needs
Authors: Prentice Ross L.
Published: November 2004

This paper, arising out of an event to honour the statistical and scientific contributions of Professor Peter Armitage, is concerned with research strategies and needs for chronic disease prevention. A few highlights from recent intervention trials for the prevention of cancer, cardiovascular disease, fractures and diabetes is provided, along with a discussion of some settings where intervention trial results seem discrepant with a body of preceding observational data. This background is used to identify research strategies and infrastructure needs for moving this vitally important research area forward, for both chemoprevention and lifestyle modification interventions. Copyright © 2004 John Wiley & Sons, Ltd.
The Effects of Plasticizers Containing Amide Groups on the Properties of Thermoplastic Starch
Authors: Ma Xiaofei , Yu Jiugao
Published: November 2004

Several amide groups‐containing plasticizers for thermoplastic starch (TPS), such as formamide, acetamide, and urea, were studied in this paper with glycerol as reference. The hydrogen bond interaction between starch and plasticizers in TPS was tested by Fourier transform infrared (FT‐IR) spectroscopy. Both the oxygen of the C‐O‐H group and the oxygen of the C‐O‐C group in starch could form hydrogen bonds with these plasticizers. The order of the hydrogen bond‐forming abilities is as follows: urea > formamide > acetamide > polyols. The retrogradation of formamide‐plasticized TPS (FPTPS), acetamide‐plasticized TPS (APTPS) and urea‐plasticized TPS (UPTPS) was investigated at three levels of relative humidity (RH=0, 50 and 100%) using X‐ray diffractometry. Urea and formamide could effectively improve the resistance of TPS towards retrogradation. The studied mechanical properties demonstrated that FPTPS had a good breaking strain but poor breaking stress, while UPTPS had opposite characteristics. The properties of TPS mainly relied on the hydrogen bond‐forming abilities between plasticizers and the starch matrix. On the other hand, the water resistance of TPS mainly depended on the plasticizer. The higher the water absorption of the plasticizer was, the better was the water resistance of the TPS.
Ligand–ligand redox interaction through some metal‐cluster units
Authors: Sasaki Yoichi , Abe Masaaki
Published: November 2004

The ligand–ligand redox interaction separated by di‐, tri‐, and hexanuclear cluster units is discussed in terms of the splitting of the redox waves (ΔE(L)) and the comproportionation constants (Kcom(L)) of the ligand‐based mixed valence state. Although two redox‐active monodentate ligands in the mononuclear ruthenium(II) complexes (either cis or trans configurations) do not show appreciable splitting in their reduction waves, interestingly those separated by giant triruthenium and hexarhenium cluster units clearly show splitting. The molecular orbital considerations in the literature suggest that these units possess some π‐type molecular orbitals composed of metal dπ and possibly ligand pπ orbitals. Absence of the redox interactions in oxo‐bridged diruthenium(II) and oxo‐centered trirhodium(III) complexes where such π molecular orbitals (including an antibonding one) are fully occupied, indicates the importance of empty π* orbitals for the ligand redox communication. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 4: 279–290; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20021