bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Properties of Functional Hybrid Organic–Inorganic Nanocomposites
Authors: Sanchez C. , Lebeau B. , Chaput F. , Boilot J.‐P.
Published: December 2003

Functional hybrids are nanocomposite materials lying at the interface of organic and inorganic realms, whose high versatility offers a wide range of possibilities to elaborate tailor‐made materials in terms of chemical and physical properties. Because they present several advantages for designing materials for optical applications (versatile and relatively facile chemistry, easy shaping and patterning, materials having good mechanical integrity and excellent optical quality), numerous silica or/and siloxane based hybrid organic–inorganic materials have been developed in the past few years. The most striking examples of functional hybrids exhibiting emission properties (solid‐state dye lasers, rare‐earth doped hybrids, electroluminescent devices), absorption properties (photochromic), nonlinear optical (NLO) properties (second‐order NLO properties, photochemical hole burning (PHB), photorefractivity), and sensing are summarized in this review.
Direct Patterning of Protein‐ and Cell‐Resistant Polymeric Monolayers and Microstructures
Authors: Khademhosseini A. , Jon S. , Suh K.Y. , Tran T.‐N.T. , Eng G. , Yeh J. , Seong J. , Langer R.
Published: December 2003

A simple technique is introduced to pattern proteins and cells with precise control over the feature topography (see Figure, white bar indicates 20 μm). The technique uses a combination of a molding process and a novel poly(ethylene glycol) copolymer to form topographical features ranging from polymeric monolayers to microstructures via simple modifications to the fabrication process.
Hydrogen‐Bond‐Directed Orientation in Nonlinear Optical Thin Films
Authors: Rashid A.N. , Erny C. , Gunter P.
Published: December 2003

A simple and effective method for the self‐assembling of thin films with directional ordering perpendicular to the substrate surface (see Figure) is reported. These films are grown on amorphous glass substrates and show second‐order nonlinear optical effects of the order of 5 pm V–1. The ordering in these films can be maintained over large thicknesses (∼800 nm), and they are homogeneous over the area of the thin film.
Low‐Temperature Electrodeposition of Room‐Temperature Ultraviolet‐Light‐Emitting Zinc Oxide
Authors: Izaki M. , Watase S. , Takahashi H.
Published: December 2003

A high‐quality (0001)‐oriented ZnO layer that emits ultraviolet light at room‐temperature has been prepared by electrodeposition on a (111) Au/(100) Si substrate. The ZnO layer emits ultraviolet light at a photon energy of around 3.3 eV due to the recombination of bound excitons and visible light at 2.34–2.8 eV at room temperature. The preparation temperature for this electrodeposition technique is several hundreds of degrees less than for other known techniques.
Synthesis of Aragonite Nanofilament Networks by Mesoscale Self‐Assembly and Transformation in Reverse Microemulsions
Authors: Li M. , Lebeau B. , Mann S.
Published: December 2003

Remarkable doughnut‐shaped micrometer‐sized aragonite particles with mesoporous sponge‐like interiors (see Figure) are spontaneously assembled in water‐in‐oil microemulsions. The structures consist of an interlinked network of complex nanofilaments that arise from the surfactant‐mediated mesoscale transformation and crystallization of amorphous CaCO3 hybrid nanoparticles.
Light‐Absorption Phenomena in Novel Low‐Reflectance Cathodes for Organic Light‐Emitting Devices Utilizing Metal–Organic Mixtures
Authors: Grandin H.M. , Aziz H. , Gardner S. , Jennings C. , Paine A.J. , Norton P.R. , Popovic Z.D.
Published: December 2003

Low‐optical‐reflectance cathodes (< 2 %, ∼ 45× lower than standard metal cathodes) utilizing a metal–organic mixed layer (MOML) have recently been developed and shown to dramatically enhance display contrast for organic light‐emitting devices. MOML characterization reveals an organic matrix with embedded metal nanoparticles (see Figure), whose surface plasmon resonance is responsible for the layer's light‐absorption properties.
Population Growth of Zooplankton (Rotifers and Cladocerans) Fed Chlorella vulgaris and Scenedesmus acutus in Different Proportions
Authors: Flores‐Burgos J. , Sarma S. S. S. , Nandini S.
Published: December 2003

In the present work we tested the effect of Chlorella vulgaris and Scenedesmus acutus in different proportions on the population growth of Brachionus calyciflorus, Brachionus patulus, Ceriodaphnia dubia, and Moina macrocopa. In general, both rotifer species grew well on either type of algae. Regardless of algal mixture, B. calyciflorus had a shorter initial phase, while B. patulus needed more than a week to begin the exponential phase of growth. Both the rotifer species showed consistently better population growth with Chlorella than on Scenedesmus, or the mixture. At any given algal combination, B. patulus had higher peak values than B. calyciflorus. The rate of population increase (r) for both the rotifers varied from 0.18 to 0.48 d—1 depending on the algal type and combination. Regardless of algal type and combination, B. calyciflorus had a much higher value of r than B. patulus. Both C. dubia and M. macrocopa grew on the algal types, whether offered separately or in mixture. Regardless of the treatment type, C. dubia needed a longer period (about 2 weeks) than M. macrocopa to reach peak abundances. Thus, our study did not support the view that Scenedesmus is consistently superior to Chlorella as a basic diet to the tested species of zooplankton.
Adsorptive Separation of 1, 2‐Dichloroethane from Model Wastewater by Natural Clinoptilolite
Authors: Pilchowski Kurt , Chmielewská Eva
Published: December 2003

The adsorptive separation of 1, 2‐dichloroethane from model wastewater by different Slovak natural and octadecylammonium‐modified clinoptilolites has been studied. It was found that the 1, 2‐dichloroethane will be adsorbed by natural as well as by surfactant‐modified clinoptilolites; all clinoptilolites have a similar adsorption loading. There was also no remarkable difference between the natural and surfactant‐modified clinoptilolites in respect to the adsorption kinetics.
Denitrification and Pesticide Elimination in Drinking Water Treatment with the Biodegradable Polymer Poly(ϵ‐caprolactone) (PCL)
Authors: Boley Angela , Mergaert Joris , Muller Claude , Lebrenz Henning , Cnockaert Margo C. , Müller Wolf‐Rüdiger , Swings Jean
Published: December 2003

A combination of denitrification and pesticide sorption with the biodegradable polymer poly(ϵ‐caprolactone) (PCL) was examined. The function of PCL is to act as carbon source and carrier for the bacteria and simultaneously as sorbent for the pesticide endosulfan.

In a short‐term examination (1 month) the addition of the pesticide endosulfan to a continuous‐flow fixed‐bed reactor resulted in an inhibition of biomass production without reduction of the denitrification performance. However in a long‐term semi‐batch reactor test (6 months) biomass production and partly denitrification rates were affected.

No significant differences in microbial composition between the reactors were observed. Regardless of the type of reactor or presence of endosulfan, Acidovorax facilis was the main constituent.
Anomalous Gadolinium, Cerium, and Yttrium Contents in the Adige and Isarco River Waters and in the Water of Their Tributaries (Provinces Trento and Bolzano/Bozen, NE Italy)
Authors: Möller Peter , Morteani Giulio , Dulski Peter
Published: December 2003

Rare earth patterns of surface and groundwaters near big cities often show anthropogenic Gd (Gdant) anomalies in addition to geogenic Ce and Y anomalies. The Gdant anomaly is caused by very stable organic complexes, one of which is gadopentetic acid, Gd‐DTPA. Derivatives of this and similar compounds are used as contrast agents in magnetic resonance imaging (MRI) of the human blood system. The organic Gd complexes are stable enough to pass nearly unaffected through sewage treatment plants and are, thereafter, discharged into surface water systems. Water of the rapidly flowing Isarco/Eisack and Adige/Etsch rivers (Provinces of Trento and Bolzano/Bozen, NE Italy) and their tributaries show remarkable variations in anthropogenic Gd contents (Gdant). Low Gdant values are found on Monday and Tuesday, whereas high values are observed during the remaining weekdays. Reliable Gdant balances are calculated for the river system at the confluence of the Adige and its tributaries. At two places local decrease of Gdant indicates exfiltration of groundwater. It is demonstrated that Gdant can be used as a reliably conservative tracer to study the water budget in rapidly flowing alpine river systems. The studied different river waters show considerable negative Ce and positive Y anomalies. Negative Ce anomalies are caused by scavenging of Ce(III) by FeO(OH) precipitates and subsequent oxidation to CeO2. Y anomalies are attributed to less sorption of Y than REE onto particulate matter. Thus, Y moves faster than REE. Both, Ce and Y anomalies, are of geogenic origin.
Pendred syndrome and DFNB4‐mutation screening of SLC26A4 by denaturing high‐performance liquid chromatography and the identification of eleven novel mutations
Authors: Prasad Sai , Kölln Karen A. , Cucci Robert A. , Trembath Richard C. , Camp Guy Van , Smith Richard J.H.
Published: December 2003

Mutations in SLC26A4 cause Pendred syndrome, an autosomal‐recessive disorder characterized by sensorineural deafness and goiter, and DFNB4, a type of autosomal recessive nonsyndromic deafness in which, by definition, affected persons do not have thyromegaly. The clinical diagnosis of these two conditions is difficult, making mutation screening of SLC26A4 a valuable test. Although screening can be accomplished in a variety of ways, all techniques are not equally accurate, timely or cost effective. We found single‐strand conformational polymorphism analysis (SSCP) to be 63% effective in detecting mutations a panel of different SLC26A4 allele variants when compared to data from direct sequencing. Because direct sequencing can be time consuming and expensive, especially for a gene with 21 exons, we studied DHPLC as an alternative screening method. We found DHPLC as accurate and reliable as direct sequencing but to be more rapid and cost effective. In addition, we report 11 novel disease‐causing allele variants of SLC26A4. © 2003 Wiley‐Liss, Inc.
Brittle cornea syndrome and its delineation from the kyphoscoliotic type of Ehlers–Danlos syndrome (EDS VI): Report on 23 patients and review of the literature
Authors: Al‐Hussain Hailah , Zeisberger Steffen M. , Huber Peter R. , Giunta Cecilia , Steinmann Beat
Published: December 2003

The brittle cornea syndrome (BCS) is a generalized connective tissue disorder characterized by corneal rupture following only minor trauma, keratoconus or keratoglobus, blue sclerae, hyperelasticity of the skin without excessive fragility, and hypermobility of the joints. It is inherited as an autosomal recessive trait but the underlying genetic defect remains undetermined. We present 23 patients (11 male) from 13 nuclear families followed at the King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia, aged 3–28 years at last follow‐up. A total of 28 events of corneal rupture were noted in 17 patients (eight male), among whom nine had had bilateral ruptures, and eight had had unilateral ruptures (four of the right cornea), while two had experienced re‐rupture 2 and 4 years, respectively, after surgery; six patients (aged 3–21 years) had had no ruptures. We describe the natural history of our cases and discuss them together with those others reported in the literature. Because of similarities between the BCS and the kyphoscoliotic type of the Ehlers–Danlos syndrome (EDS VI), both disorders tend to have been confounded. Here, we show that all of our BCS patients tested in this regard had biochemical findings reflective of normal activity of lysyl hydroxylase, characteristically deficient in EDS VI, such as normal urinary total pyridinoline ratios and/or normal electrophoretic migration of collagen chains produced by dermal fibroblasts. The BCS is, therefore, an entity distinct from the kyphoscoliotic type of EDS, which has a much poorer prognosis. © 2003 Wiley‐Liss, Inc.
Molecular cytogenetic characterization of a recombinant chromosome rec(22)dup(22q)inv(22)(p13q12.2)
Authors: Tonk Vijay S. , Jesurun C.A. , Morgan David L. , Lockhart Lillian H. , Velagaleti Gopalrao V.N.
Published: December 2003

Pericentric inversions occur at a frequency of 0.12–0.7% in humans. However, pericentric inversions of chromosome 22 appear to be common, especially in patients originating from the Guadalajara region of Mexico. Here, we report a seventh case of a pericentric inversion of chromosome 22, the resulting recombinant chromosome, and describe the phenotypic features associated with such a recombinant chromosome. It is interesting that five of the seven patients with inv(22) come from Mexico, and four of the five patients from the Guadalajara region. © 2003 Wiley‐Liss, Inc.
Prenatal diagnosis of fetal trisomy 6 mosaicism and phenotype of the affected newborn
Authors: Wegner Rolf‐Dieter , Entezami Michael , Knoll Ute , Horn Denise , Sohl Susanne , Becker Rolf
Published: December 2003

The first case of a fetal trisomy 6 mosaicism proven at 25 weeks of gestation by analysis of fetal urine cells is described. Chromosomal analysis was indicated by an ultrasonographically diagnosed heart defect at 21 weeks of gestation. The chromosomal aberration was detected in amniotic fluid cells while fetal blood cells showed a normal chromosome set. At term a boy with normal growth parameter was born. In addition to the expected heart defect, malformations of hands and feet were present. © 2003 Wiley‐Liss, Inc.
Desbuquois dysplasia, a reevaluation with abnormal and “normal” hands: Radiographic manifestations
Authors: Faivre Laurence , Cormier‐Daire Valérie , Eliott Alison M. , Field Fiona , Munnich Arnold , Maroteaux Pierre , Merrer Martine Le , Lachman Ralph
Published: December 2003

Radiological features of 35 patients with the diagnosis of Desbuquois dysplasia were analyzed. The diagnosis of Desbuquois dysplasia was based on the association of specific facial alterations, markedly short stature of prenatal onset, joint laxity, ‘Swedish key’ appearance of the proximal femur, and advanced carpal and tarsal bone age. Patients were divided into two groups, depending on whether or not typical hands with an extra ossification center distal to the second metacarpal and/or a delta phalanx of the thumb were present (group 1, 46%) or absent (group 2, 54%). In this study, beside the ‘Swedish key’ appearance of the proximal femur and advanced carpal and tarsal ossification, we were able to define three additional major radiographic criteria for the diagnosis of Desbuquois dysplasia, including flat acetabular roof, elevated greater trochanter, and proximal fibular overgrowth. Other manifestations included wide metaphyses, flat epiphyses, coxa valga, coronal and saggital clefts of the vertebrae, wide anterior rib portions, medial deviation of the foot, and enlarged first metatarsal. We conclude that characteristic hand abnormalities are not mandatory for the diagnosis of Desbuquois dysplasia. © 2003 Wiley‐Liss, Inc.
Long‐term outcome in desbuquois dysplasia: A follow‐up in four adult patients
Authors: Faivre Laurence , Cormier‐Daire Valérie , Young Ian , Bracq Henri , Finidori Georges , Padovani Jean Paul , Odent Sylvie , Lachman Ralph , Munnich Arnold , Maroteaux Pierre , Merrer Martine Le
Published: December 2003

Desbuquois dysplasia is a rare chondrodysplasia characterized by short stature, joint laxity, and specific radiographic findings. We report the natural history of four patients (three boys and one girl) with Desbuquois dysplasia ages 16–22 years. The mean height in adulthood was 114 cm (−8.5 SD) with progressive deceleration of the growth curve from birth (−4 SD) to adulthood. Obesity was noted consistently and facial abnormalities were still present but less obvious than in childhood. Three of four patients had mental retardation of varying degree. Hyperlaxity was persistent but limited motion of various joints was also noted. Orthopedic complications included coxa vara or valga (3/4), scoliosis (3/4), marked lordosis (3/4), and ambulatory difficulties (3/4). Surgical treatment was necessary for all four patients, involving large joints, spine and hands. Other complications included acute open‐angle glaucoma secondary to a congenital malformation of the angle in one case. In addition to consistent radiological findings, elevated greater trochanter, generalized osteoporosis especially of the spine, scoliosis and/or lordosis, wide metaphyses, flat epiphyses, and coxa vara or valga were part of the natural history of the disorder. Our study emphasizes the care of older patients with Desbuquois dysplasia. © 2003 Wiley‐Liss, Inc.
Magnetic resonance imaging shows delayed ischemic striatal neurodegeneration
Authors: Fujioka Masayuki , Taoka Toshiaki , Matsuo Yoshiyuki , Mishima Kenichi , Ogoshi Kumiko , Kondo Yoichi , Tsuda Masakazu , Fujiwara Michihiro , Asano Takao , Sakaki Toshisuke , Miyasaki Akihiro , Park Darren , Siesjö Bo K.
Published: December 2003

Brief focal ischemia leading to temporary neurological deficits induces delayed hyperintensity on T1‐weighted magnetic resonance imaging (MRI) in the striatum of humans and rats. The T1 hyperintensity may stem from biochemical alterations including manganese (Mn) accumulation after ischemia. To clarify the significance of this MRI modification, we investigated the changes in the dorsolateral striatum of rats from 4 hours through 16 weeks after a 15‐minute period of middle cerebral artery occlusion (MCAO), for MRI changes, Mn concentration, neuronal number, reactivities of astrocytes and microglia/macrophages, mitochondrial Mn‐superoxide dismutase (Mn‐SOD), glutamine synthetase (GS), and amyloid precursor protein. The cognitive and behavioral studies were performed in patients and rats and compared with striatal T1 hyperintensity to show whether alteration in brain function correlated with MRI and histological changes. The T1‐weighted MRI signal intensity of the dorsolateral striatum increased from 5 days to 4 weeks after 15‐minute MCAO, and subsequently decreased until 16 weeks. The Mn concentration of the dorsolateral striatum increased after ischemia in concert with induction of Mn‐SOD and GS in reactive astrocytes. The neuronal survival ratio in the dorsolateral striatum decreased significantly from 4 hours through 16 weeks, accompanied by extracellular amyloid precursor protein accumulation and chronic glial/inflammatory responses. The patients and rats with neuroradiological striatal degeneration had late‐onset cognitive and/or behavioral declines after brief focal ischemia. This study suggests that (1) the hyperintensity on T1‐weighted MRI after mild ischemia may involve tissue Mn accumulation accompanied by Mn‐SOD and GS induction in reactive astrocytes, (2) the MRI changes correspond to striatal neurodegeneration with a chronic inflammatory response and signs of oxidative stress, and (3) the subjects with these MRI changes are at risk for showing a late impairment of brain function even though the transient ischemia is followed by total neurological recovery. Ann Neurol 2003;54:732–747
The expanding mutational spectrum of MERRF substitution G8361A in the mitochondrial tRNALys gene
Authors: Rossmanith Walter , Raffelsberger Thomas , Roka Julia , Kornek Barbara , Feucht Martha , Bittner Reginald E.
Published: December 2003

In a case of childhood‐onset myoclonus epilepsy with “ragged‐red fibers” (MERRF), a hitherto unreported mutation within the mitochondrial tRNALys gene was identified as the cause of the disease. Substitution G8361A was maternally inherited, heteroplasmic in all tissues tested, and correlated with mitochondrial dysfunction in individual muscle fibers. The growing number of MERRF‐associated mutations within the tRNALys gene affirms the specific role of this mitochondrial tRNA in the pathogenesis of the disease.
Chlamydia pneumoniae and the risk for exacerbation in multiple sclerosis patients
Authors: Buljevac Dragan , Verkooyen Roel P. , Jacobs Bart C. , Hop Wim , van der Zwaan Liesbeth A. , van Doorn Pieter A. , Hintzen Rogier Q.
Published: December 2003

In this prospective study of 73 relapsing remitting multiple sclerosis patients followed up for a mean of 1.7 years, the relation was tested between serologically defined Chlamydia pneumoniae (CP) infection periods and exacerbation rate. Episodes of serologically defined CP infections were observed in a subgroup, and these episodes were associated with increased risk for exacerbation. CP polymerase chain reaction was positive in most of the CP seropositive patients. No correlation was found between the anti–CP antibody increase and titers of control antibodies.
Insertion of mutant proteolipid protein results in missorting of myelin proteins
Authors: Vaurs‐Barriere Catherine , Wong Kondi , Weibel Thais D. , Abu‐Asab Mones , Weiss Michael D. , Kaneski Christine R. , Mixon Tong‐Hui , Bonavita Simona , Creveaux Isabelle , Heiss John D. , Tsokos Maria , Goldin Ehud , Quarles Richard H. , Boespflug‐Tanguy Odile , Schiffmann Raphael
Published: December 2003

Two brothers with a leukodystrophy, progressive spastic diplegia, and peripheral neuropathy were found to have proteinaceous aggregates in the peripheral nerve myelin sheath. The patients' mother had only subclinical peripheral neuropathy, but the maternal grandmother had adult‐onset leukodystrophy. Sequencing of the proteolipid protein (PLP) gene showed a point mutation IVS4 + 1 G→A within the donor splice site of intron 4. We identified one transcript with a deletion of exon 4 (Δex4, 169bp) encoding for PLP and DM20 proteins and lacking two transmembrane domains, and a second transcript with exon 4 + 10bp encoding three transmembrane domains. Immunohistochemistry showed abnormal aggregation in the myelin sheath of MBP and P0. Myelin‐associated glycoprotein was present in the Schmidt–Lanterman clefts but significantly reduced in the periaxonal region. Using immunogold electron microscopy, we demonstrated the presence of mutated PLP/DM20 and the absence of the intact protein in the patient peripheral myelin sheath. We conclude that insertion of mutant PLP/DM20 with resulting aberrant distribution of other myelin proteins in peripheral nerve may constitute an important mechanism of dysmyelination in disorders associated with PLP mutations. Ann Neurol 2003;54:769–780
Ribonuclear inclusions in skeletal muscle in myotonic dystrophy types 1 and 2
Authors: Mankodi Ami , Teng‐Umnuay Patana , Krym Matt , Henderson Don , Swanson Maurice , Thornton Charles A.
Published: December 2003

Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are caused by genomic expansions of CTG or CCTG repeats. When transcribed, these mutations give rise to repeat expansion RNAs that form nuclear inclusions and compromise the function of myonuclei. Here, we have used in situ hybridization and immunofluorescence to compare DM1 and DM2 and search for proteins that associate with the RNA nuclear (ribonuclear) inclusions. Although muscle disease is generally more severe in DM1, the ribonuclear inclusions were 8‐ to 13‐fold more intense in DM2, implying greater amounts of repeat expansion RNA. Expression of repeat expansion RNA in myoblasts has been implicated in the pathogenesis of congenital DM1. However, we found that repeat expansion RNA is also expressed in myoblasts in DM2, a disorder that has not been associated with a congenital phenotype. Of 10 putative CUG binding proteins tested for colocalization with mutant RNA, only proteins in the muscleblind family were recruited into ribonuclear inclusions. Previous studies have shown activation of the protein kinase, PKR, by expanded CUG repeats in vitro. However, breeding experiments utilizing PKR knockout mice indicate that this kinase is not required for disease pathogenesis in a transgenic mouse model of DM1. We conclude that ribonuclear inclusions are a key feature of the muscle pathology in DM and that sequestration of muscleblind proteins may have a direct role in the disease process. Ann Neurol 2003;54:760–768
Myofibrillar myopathy caused by novel dominant negative αB‐crystallin mutations
Authors: Selcen Duygu , Engel Andrew G.
Published: December 2003

We here report the second and third mutations in αB‐crystallin causing myofibrillar myopathy. Two patients had adult‐onset muscle weakness. Patient 1 had cervical, limb girdle, and respiratory muscle weakness and died of respiratory failure. Patient 2 had proximal and distal leg muscle weakness. Both had myopathic electromyogram with abnormal electrical irritability and muscle biopsy findings of myofibrillar myopathy and mild denervation. Myofibrillar disintegration begins at the Z‐disk and results in abnormal local expression of desmin, αB‐crystallin, dystrophin, neural cell adhesion molecule (NCAM), and CDC2 kinase. Seven to 8% of nuclei display early apoptotic changes. Both patients carry a truncating mutation in the C‐terminal region of αB‐crystallin (464delCT in Patient 1 and Q151X in Patient 2) which is crucial for the solubilization and chaperone functions of the molecule. cDNA analysis shows the same mutations and no alternatively spliced transcripts. Immunoblots of muscle demonstrate increased expression of wild‐type and reduced expression of the mutant protein. Immunoblots under nondenaturing conditions show that the mutant protein forms lower than normal molecular weight multimeric complexes with wild type. We conclude that (1) despite its reduced expression, the mutant protein exerts a dominant negative effect; (2) mutations in αB‐crystallin are an infrequent cause of myofibrillar myopathy; (3) αB‐crystallin–related myopathies display phenotypic heterogeneity. Ann Neurol 2003;54:804–810
Domänen und Rafts in Lipidmembranen
Authors: Binder Wolfgang H. , Barragan Veronique , Menger Fredric M.
Published: December 2003

“It takes a membrane to make sense out of disorder in biology. You have to be able to catch energy and hold it, storing precisely the needed amount and releasing it in measured shares.” Die herausragende Rolle von Domänen und “Rafts” für das von Lewis Thomas in The Lives of Cells so treffend beschriebene Verhalten von Lipidmembranen ist Gegenstand dieses Aufsatzes. Erläutert wird der experimentelle Nachweis, der Aufbau und die Bildung von Domänen sowie die Eigenschaften von Rafts – einer speziellen Form von Domäne – und ihr möglicher Einfluss auf menschliche Krankheiten. Lipide, Polymere und Proteine können zu solchen Mikro‐ und Nanostrukturierungen innerhalb einer Membran beitragen, wodurch ein neuer Typ struktureller Ordnung in Doppelschichtmembranen entsteht. Ein Verständnis für diese unterschiedlichen Arten von Ordnungen innerhalb selbstorganisierter Systeme zu vermitteln, ist vorrangiges Ziel dieses Aufsatzes.
Titelbild: Breaking Down Barriers: The Liaison Between Sigmatropic Shifts, Electrocyclic Reactions, and Three‐Center Cations (Angew. Chem. 47/2003)
Authors: Hoffmann Roald , Tantillo Dean J.
Published: December 2003

Die Prinzipien der Orbitalsymmetrie‐Kontrolle wurden vor fast 40 Jahren von Woodward und Hoffmann entdeckt. Jetzt warten R. Hoffmann und D. J. Tantillo mit überraschenden neuen Erkenntnissen auf: Die Übergangszustände (nicht die Reaktanten oder Produkte) von elektrocyclischen Reaktionen und sigmatropen Verschiebungen zeigen eine erstaunliche Übereinstimmung – sie unterscheiden sich nur in einem einzigen Proton! Die Autoren erklären in ihrer Zuschrift auf S. 6057 ff. die Ergebnisse mit dem Konzept der Übergangszustands‐Protonenaffinität.
Nonequilibrium particle morphology development in seeded emulsion polymerization. III. Effect of initiator end groups
Authors: Stubbs Jeffrey M. , Sundberg Donald C.
Published: December 2003

In previous work (L. Karlsson et al., Journal of Applied Polymer Science, 2002, 2003, Vol. 90, pp. 905–915; J. M. Stubbs et al., Colloids and Surfaces A: Physiochemical and Engineering Aspects, 1999, Vol. 153, pp. 255–270) we have explained the development of composite particle morphologies produced by seeded emulsion polymerization in terms of the ability of second stage polymer radicals to diffuse into, or “penetrate,” the seed particles. This has been quantified (Stubbs et al., ibid) by calculating so‐called “fractional penetration” values for the second‐stage radicals. In this article the effect of the second‐stage initiator type, specifically nonionic vs ionic initiators, on particle morphology is investigated. The question to be answered is whether charged (ionic) end groups (from the initiator) on second stage polymer chains “anchor” to the particle surface, making it more likely to form core–shell morphologies. This is investigated by using a poly(methyl acrylate‐co‐methyl methacrylate) [P(MA‐co‐MMA)] seed latex and polymerizing styrene in the second stage in a semibatch manner using various feed rates of styrene. At each feed rate one reaction was conducted using potassium persulfate as the initiator, which produces charged end groups, and another using VA‐086 initiator, which produces uncharged end groups. The morphologies of the resulting particles were then observed by transmission electron microscopy. It is shown that under some conditions ionic initiators do make it more likely to obtain core‐shell morphologies, but that this effect is not dominant under most conditions. The resulting morphologies agree quite well with the predictions of the fractional penetration calculations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1538–1551, 2004
Influence of plasticizer type and storage conditions on properties of poly(methyl vinyl ether‐co‐maleic anhydride) bioadhesive films
Authors: McCarron Paul A. , Woolfson A. David , Donnelly Ryan F. , Andrews Gavin P. , Zawislak Agnieszka , Price John H.
Published: December 2003

Poly(methyl vinyl ether‐co‐maleic anhydride) formed films from aqueous formulations with characteristics that are ideal as a basis for producing a drug‐containing bioadhesive delivery system when plasticized with a monohydroxyl functionalized plasticizer. Hence, films containing a novel plasticizer, tripropylene glycol methyl ether (TPME), maintained their adhesive strength and tensile properties when packaged in aluminized foil for extended periods of time. Films plasticized with commonly used polyhydric alcohols, such as the glycerol in this study, underwent an esterification reaction that led to polymer crosslinking, as shown in NMR studies. These revealed the presence of peaks in the ester/carbonyl region, suggesting that glyceride residue formation had been initiated. Given the polyfunctional nature of glycerol, progressive esterification would result in a polyester network and an accompanying profound alteration in the physical characteristics. Indeed, films became brittle over time with a loss of both the aqueous solubility and bioadhesion to porcine skin. In addition, a swelling index was measurable after 7 days, a property not seen with those films containing TPME. This change in bioadhesive strength and pliability was independent of the packaging conditions, rendering the films that contain glycerol as unsuitable as a basis for topical bioadhesive delivery of drug substances. Consequently, films containing TPME have potential as an alternative formulation strategy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1576–1589, 2004
Performance of neural networks for predicting yarn properties using principal component analysis
Authors: Chattopadhyay R. , Guha Anirban , Jayadeva
Published: December 2003

In recent years, neural networks have been used as a tool for modeling an industrial process. An improvement in their performance may be expected either by divining more efficient training algorithms or by intelligently manipulating the data set. The second method is examined. The problem chosen is one of predicting the properties of cotton yarn from the fiber properties. When the input data are known to correlate with each other, principal component analysis can be used to improve the performance of neural networks. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1746–1751, 2004
Studies of electrical and mechanical properties of poly(vinyl chloride) mixed with electrically conductive additives
Authors: Saad A. L. G. , Aziz H. A. , Dimitry O. I. H.
Published: December 2003

Different samples of poly(vinyl chloride) (PVC) compositions were formulated from PVC, a polar plasticizer such as dioctylphthalate (DOP), and variable proportions of electrically conductive additives such as fast extrusion furnace (FEF) carbon black (CB), poly(vinylpyridine) (PVP), or polyacrylonitrile (PAN). Epoxidized soybean oil was added as a heat stabilizer. Samples of the PVC–CB system were also prepared by dispersing different concentrations of CB into the PVC matrix. The electrical studies showed that the addition of CB to the PVC–DOP system produces a plasticized PVC with high electrical conductivity whereas the compounding of PVC with CB produces a sample with much higher electrical conductivity. The effect of the structure of PVP and PAN on the electrical and mechanical properties of the PVC–DOP system was also studied to obtain a semiconductive plasticized PVC with good mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1590–1598, 2004
Poly(N‐vinylcarbazole)–clay nanocomposite materials prepared by photoinitiated polymerization with triarylsulfonium salt initiator
Authors: Yu Yuan‐Hsiang , Lin Ching‐Yi , Yeh Jui‐Ming
Published: December 2003

A series of polymer–clay nanocomposite (PCN) materials that consist of poly(N‐vinylcarbazole) (PNVC) and layered montmorillonite (MMT) clay are prepared by effectively dispersing the inorganic nanolayers of MMT in an organic PNVC matrix via in situ photoinitiated polymerization with triarylsulfonium salt as the initiator. Organic NVC monomers are first intercalated into the interlayer regions of the organophilic clay hosts, followed by one‐step UV‐radiation polymerization. The as‐synthesized PCN materials are typically characterized by Fourier transform IR spectroscopy, wide‐angle X‐ray diffraction, and transmission electron microscopy. The molecular weights of PNVCs extracted from the PCN materials and the bulk PNVC are determined by gel permeation chromatography analysis with tetrahydrofuran as the eluant. The morphological image of the synthesized materials is observed by an optical polarizing microscope. The effects of the material composition on the optical properties and thermal stability of PNVCs and a series of PCN materials (solution and fine powder) are also studied by UV–visible absorption spectra measurements, thermogravimetric analysis, and differential scanning calorimetry, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1904–1912, 2004
Self crosslinkable blends of polychloroprene and phosphorylated cashew nut shell liquid prepolymer
Authors: Menon A. R. R. , Visconte L. L. Y.
Published: December 2003

The self crosslinking behavior of polychloroprene rubber (CR) containing phosphorylated cashew nut shell liquid (PCNSL) prepolymer was studied. The cure characteristics and kinetics of crosslinking of blends of CR and PCNSL were determined using an oscillating disk rheometer. The extent of crosslinking was determined from chemical crosslink density index obtained by equilibrium swelling method in a solvent. Evidence for heat induced self crosslinking was obtained from FTIR spectroscopy. It was found that 5 to 10 phr of PCNSL accelerates the heat induced self crosslinking behavior of CR. The effect of conventional curatives and fillers on the cure characteristics and mechanical properties of CR was also studied and compared. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1619–1625, 2004
Uptake of Pb(II) and Cd(II) by a new phenolformaldehyde polymer resin derived by the insertion of sulfur ligands in the form of xanthate
Authors: Reddy A. Ravikumar , Reddy K. Hussain
Published: December 2003

A new phenolformaldehyde polymer resin containing potential soft‐type donor atoms (sulfur atoms) was synthesized by the reaction of sodium salt of 2,4‐dihydroxyacetophenone formaldehyde resin with carbon disulfide. The resin was characterized by elemental analysis, IR, and 1H‐NMR spectral studies. Because of its insolubility in aqueous media, the resin was successfully used in the removal of Pb(II) and Cd(II). Parameters such as the effect of pH, the effect of time, competitive studies, the effect of initial metal‐ion concentration, and the recyclability of the polymer resin were studied. The amount of metal removed by the resin was determined with atomic absorption spectrophotometry. The retention properties were strongly dependent on pH. The elution of metal ions was investigated in acid media. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1932–1936, 2004
Morphology, crystallization and melting properties of isotactic polypropylene blended with lignin
Authors: Canetti Maurizio , De Chirico Aurelio , Audisio Guido
Published: December 2003

The influence of lignin (L) on the thermal properties and kinetics of crystallization of isotactic polypropylene (PP) is reported in this article. PP blends containing 5 and 15 wt % of L were prepared by mixing the components in a screw mixer. An increase of the thermal degradation temperature of the blends was observed as a function of L content. The crystallization and thermal behavior of the pure PP and of the PP/L blends were analyzed by differential scanning calorimetry (DSC). Isothermal crystallization kinetics were described by means of the Avrami equation, which suggests a three‐dimensional growth of crystalline units, developed by heterogeneous nucleation. The isothermal growth rate of PP spherulites was studied using a polarizing optical microscope. The enhancement of PP crystallization rate for the PP/L blends was observed and ascribed to the nucleating action of lignin particles. Non‐isothermal crystallization kinetics were applied, according to the results elaborated by Ziabicki and the method modified by Jeziorny. The kinetic crystallizability of the PP is not influenced by the L present in the blend. In the presence of L, PP can simultaneously crystallize in both the α and β crystalline forms, and the ratio between the α and β forms was determined by X‐ray diffraction analysis. Two melting peaks relative to the two crystalline form of PP were observed for the PP/L blends, for all isothermal crystallization temperatures investigated by means of DSC. The equilibrium melting temperature for α‐form of pure PP was obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1435–1442, 2004
Experimental and theoretical studies of polymer/solvent viscosity mixtures
Authors: Modarress Hamid , Mohsen‐Nia Mohsen , Mahdavi Mahmood Akhavan
Published: December 2003

Viscosity of the binary mixtures of polymers/solvent: (polystyrene/toluene), (polymethylmethacrylate/acetone), (polystyrene/benzene), (polystyrene/cyclohexane), and (polymethylmethacrylate/chloroform) were measured at different temperatures by a Haake viscometer. The samples of polymer/solvents mixtures used in the viscometry measurements were in low concentration of polymer (maximum concentration 0.25 g/cm3). The measured viscosities were used to evaluate the parameters of the modified Eyring's viscosity equation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1724–1729, 2004
Kinetics of the in situ polymerization and in situ compatibilization of poly(propylene) and polyamide 6 blends
Authors: Hu Guo‐Hua , Cartier Hervé , Feng Lian‐Fang , Li Bo‐Geng
Published: December 2003

In previous articles, we reported on a novel reactive extrusion process to obtain a compatibilized blend of polymer A and polymer B. It consisted in polymerizing the monomer of polymer A in the presence of polymer B. A fraction of the latter contained initiating sites from which the polymerization of monomer A took place. As such, both polymer A and a graft copolymer of polymer A and polymer B were formed in the process. That process was called in situ polymerization and in situ compatibilization of polymer blends. Its feasibility was illustrated for in situ polymerized and in situ compatibilized poly(propylene) and polyamide 6 (PP/PA6) blends. The latter were prepared by activated anionic polymerization of ϵ‐caprolactam (CL) in the presence of PP in a batch mixer and a twin‐screw extruder, respectively. A fraction of the PP contained isocyanate groups from which PA6 grafts were formed. Sodium caprolactam (NaCL) was used as the catalyst and a diisocyanate compound was used as the activator. In this study, we report on the effects of various parameters on the kinetics of the anionic polymerization of CL in the presence of PP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1498–1504, 2004
Dielectric strength of the blends of virgin and recycled HDPE
Authors: Cruz S. A. , Zanin M.
Published: December 2003

This work evaluated the incorporation of recycled high‐density polyethylene (HPDE) in the virgin polymer by measuring its dielectric strength. Post‐consumer containers of HDPE were collected and passed through the basic processes of plastics recovery: washing, grinding, and drying. Formulations were elaborated containing 0, 25, 50, 75, and 100% of recycled material incorporated to the virgin resin by extrusion and injection processes, stabilized with 0.2% Irganox B215. Samples of these materials were submitted to dielectric breakdown analysis by using an electrode‐type sphere—plane and ramp of positive electric tension. The data were treated and analyzed by using the statistical distribution of Weibull, and the Maximum Likelihood method. The degree of crystallinity was measured by X‐ray diffraction. Atomic absorption spectrophotometry was employed to identify metallic residues present in the samples. The results showed that there is a 17% decrease in the values of the dielectric strength when we compare the virgin HDPE with the 100% recycled. Therefore, formulations containing up to 50% of recycled material may be taken into consideration in the development of products in electric insulating systems.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91:1730–1735, 2004
Study of microwave irradiation polymerization mechanism in the presence of carriers
Authors: Lu Jianmei , Ji Shun‐Jun , Wu Jianfei , Guo Feng , Zhou Hui , Zhu Xiulin
Published: December 2003

Microwave irradiation polymerization was studied in the presence of a carrier. The influence of different carriers, such as Al2O3, SiO2, and MgO on the microwave irradiation polymerization mechanism of acrylamide and 2‐ethylhexyl acrylate was studied by adopting polymerization inhibitors such as an anionic inhibitor, cationic inhibitor, and radical inhibitor hydroquinone. When the system contains the carriers Al2O3 and SiO2, the polymerization mechanism occurs according to a radical mechanism, but when the system contains MgO, the polymerization mechanism occurs according to not only a radical mechanism but also an anionic polymerization mechanism with superficial grafting occurring. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1519–1524, 2004
Compatibilized blends of PVC/PA12 and PVC/PP containing poly(lauryl lactam‐block‐caprolactone)
Authors: Kim Byong Jun , White James L.
Published: December 2003

Specially designed block copolymers have played a role as compatibilizing agents in the system of immiscible polymer blends. We applied lauryl lactam (LA)–caprolactone (CL) block copolymer [P(LA‐b‐CL)] as a compatibilizing agent for immiscible poly(vinyl chloride) (PVC) blends with various polymers. These blends possess high thermal performance and toughness. We investigated the effect of P(LA‐b‐CL) as a compatibilizing agent for immiscible PVC blends with poly(ω‐lauryl lactam) [polyamide 12 (PA12)]. We also described the invention of a new compatibilizing agent system involving P(LA‐b‐CL) for PVC/polypropylene (PP) blends. The mechanical and thermal properties of (1) PVC/PA12 blend compatibilized with P(LA‐b‐CL) and (2) PVC/PP blend compatibilized with P(LA‐b‐CL)/PA12/maleic anhydride–modified PP were both enhanced. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1983‐1992, 2004
Bonding of vulcanized rubber to polyester cord using RFL adhesives modified with chlororesorcinolic resin
Authors: Hamed G. R. , Ruksakulpiwat C.
Published: December 2003

A typical resorcinol/formaldehyde/latex (RFL) adhesive and two modified versions were used to bond a tire body stock (NR/SBR/BR blend) to polyethylene terephthalate (PET) cord. Modifications contained a commercial chlorophenol/resorcinol condensate or a lab‐prepared chlororesorcinol/resorcinol condensate (CRA). Standard H‐test specimens were prepared by embedding adhesive‐coated, heat‐treated cords into the rubber and then vulcanizing. The effect of heat treatment time and overcure on pull‐out adhesion was studied. Overcure conditions were used to simulate long service. Pull‐out forces increased with longer heat treatment and decreased with overcure. The CRA‐modified adhesive gave the highest pull‐out forces after overcure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91:1993–1996, 2004
An analysis of the changes in the structure and tensile properties of polytetrafluoroethylene films under vacuum ultraviolet irradiation
Authors: Peng Guirong , Geng Hongbin , Lü Zushun , Yang Dezhuang , He Shiyu
Published: December 2003

The effect of 5–200 nm of vacuum ultraviolet (VUV) irradiation on the structure and tensile properties of polytetrafluoroethylene (PTFE) films was investigated. The change in structure before and after VUV irradiation was evaluated with differential scanning calorimetry (DSC) and electron spin resonance (ESR) analysis. DSC analysis results showed that the melting point, melting enthalpy, and crystallization enthalpy increased and the maximum crystallization temperature decreased a little with increasing VUV dose. It was deduced from the DSC data that the molecular weight of the PTFE films decreased and the destruction of the crystal structure took place under VUV irradiation. The ESR results showed that the radicals formed under VUV irradiation were chain‐end radicals and peroxy radicals, which may have been formed due to the scission of carbon‐to‐carbon bonds. The tensile fracture strength and elongation decreased with increasing VUV irradiation dose. Under the same irradiation dose, the tensile properties were more sensitive to the lower VUV intensity. The decrease in the molecular weight and the destruction of crystal structure might have been the major reasons for the deterioration of the tensile properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1494–1497, 2004
Synthesis, characterization, and partial hydrolysis of polyisoprene‐co‐poly(tert‐butyl methacrylate) and electrorheological properties of its suspensions
Authors: Yavuz Mustafa , Ibrahim Ünal Halil
Published: December 2003

The synthesis, characterization, partial hydrolysis, and salt formation of polyisoprene‐co‐poly(tert‐butyl methacrylate) and the electrorheological properties of its suspensions were investigated. The copolymer was characterized by gel permeation chromatography, viscosity measurements, 1H‐NMR, Fourier transform infrared spectroscopy, particle size measurements, and elemental analysis. The poly(tert‐butyl methacrylate) units of the copolymer were partially hydrolyzed by p‐toluene sulfonic acid monohydrate and then converted into a lithium salt. The conductivity of this copolymeric salt was measured to be 1.4 × 10−9 S cm−1. Suspensions of the copolymeric salt were prepared in four insulating oils (silicone oil, mineral oil, trioctyl trimellitate, and dioctyl phatalate) in a series of concentrations (5–33%, m/m). The gravitational stabilities of these suspensions were determined at 20 and 80°C. The flow times of the suspensions were measured under no electric field (electric field strength = 0) and under an applied electric field (electric field strength ≠ 0), and the electrorheological activity was observed. Furthermore, the effects of the solid particle concentration, the shear rate, the electric field strength, a high temperature, and the addition of promoters on the electrorheological activities of the suspensions were investigated, and the excess shear stresses were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1822–1833, 2004