bluuebunny/crossref_metadata_2025 huggingface dataset:
One‐step functionalization of an ethylene/propylene random copolymer with two different reactive groups
Authors: Passaglia Elisa , Corsi Leopoldo , Aglietto Mauro , Ciardelli Francesco , Michelotti Marco , Suffredini Giampiero
Published: November 2002

The efficiency of a macromolecular compatibilizer for reactive blending is strongly dependent on its potentiality of producing a grafted or block copolymer during processing. For the preparation of such a compatibilizer, the grafting of two different reactive groups onto the backbones of ethylene/propylene copolymer macromolecules was performed. The ethylene/propylene (70/30) copolymer was then processed in a Brabender mixer at 190°C in the presence of a mixture of maleic anhydride and diethylmaleate with either dicumyl peroxide or di‐tert‐butyl peroxide as an initiator. The experiments clearly showed that the two functionalities, 2‐diethyl succinate and 2‐succinic anhydride, could be grafted in one step. The effect of the feed composition demonstrated that the two monomers influenced the reciprocal reactivity and the resulting product. A detailed Fourier transform infrared analysis of the grafted macromolecules was performed, and the respective amounts of ester and anhydride derived groups were detected by deconvolution of the vibrational bands in the carbonyl spectral region. The validity of the process on an industrial scale was tested by the successful performance of the reaction in a twin‐screw extruder. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 14–23, 2003
Chemical modification of polydienic elastomers by organophosphorated reagents
Authors: Derouet Daniel , Brosse Jean‐Claude , Cauret Laurent , Morvan Frédérique , Mulder‐Houdayer Stéphanie
Published: November 2002

The synthesis of 1,4‐polyisoprenes bearing organophosphorated groups in the side positions of polydiene chains was considered with a chemical modification procedure. The grafting of phosphorated groups along polyisoprene chains was carried out via the reaction of the acid functionality (POH) of phosphate or phosphonate acid reagents with oxirane rings previously created on a 1,4‐polyisoprene backbone. The reagents considered were dibutylphosphate and 2‐chloroethylphosphonic acid. The purpose was to compare the action of these two reagents toward epoxidized units of 1,4‐epoxidized polyisoprenes in various media (solvent, bulk, and latex). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 47–60, 2003
CARD15 mutations in familial granulomatosis syndromes: A study of the original Blau syndrome kindred and other families with large‐vessel arteritis and cranial neuropathy
Authors: Wang Xiaoju , Kuivaniemi Helena , Bonavita Gina , Mutkus Lysette , Mau Ulrike , Blau Edward , Inohara Naohiro , Nunez Gabriel , Tromp Gerard , Williams Charlene J.
Published: November 2002

Objective

To analyze the CARD15 gene in families with heritable multi‐organ granulomatoses, including the original Blau syndrome kindred as well as other families with related granulomatous conditions.

Methods

Linkage mapping was performed in 10 families. Observed recombination events were used to exclude regions centromeric or telomeric to 16q12.1, and the Blau gene critical region was refined to <3 cM, corresponding to a physical distance of 3.5 megabasepairs. Based on its known biochemical function, CARD15 was analyzed as a positional candidate for the Blau syndrome susceptibility gene, by direct DNA sequencing.

Results

These studies resulted in the identification, in 5 of the families, of 2 sequence variants at position 334 of the gene product (R334W and R334Q). Affected family members from the original Blau syndrome kindred were heterozygous for the R334W missense mutation; mutations at the same position were also observed in several unrelated Blau syndrome families, some of whose phenotypes included large‐vessel arteritis and cranial neuropathy. The missense mutations segregated with the disease phenotype in the families, and were not seen in 208 control alleles.

Conclusion

These findings demonstrate that CARD15 is an important susceptibility gene for Blau syndrome and for other familial granulomatoses that display phenotypic traits beyond those of classic Blau syndrome.
Distribution of thyrotropin‐releasing hormone immunoreactivity in the brain of larval and adult sea lampreys, Petromyzon marinus L.
Authors: Del Carmen De Andrés María , Anadón Ramón , Manso María Jesús , González María José
Published: October 2002

This study investigated the distribution of thyrotropin‐releasing hormone‐immunoreactive (TRHir) neurons and fibers in the brain and retina of lampreys. Our results in the brains of large larvae and upstream‐migrating adults of the sea lamprey showed the presence of TRHir neurons mainly in the preoptic region and the hypothalamus. A few TRHir neurons were also found in the striatum. The number and staining intensity of TRHir neurons increased from larval stages to adulthood, and the distribution of TRHir populations was wider in adults. The TRHir fibers were more easily traced in adults. Some TRHir fibers entered the neurohypophysis, although most fibers coursed in the different regions of the brain, mostly in the basal region, from the forebrain to the hindbrain. The presence of TRHir stellate cells was observed in the adenohypophysis. In the retina of adult lampreys, but not in that of larvae, TRHir amacrine cells are present. J. Comp. Neurol. 453:323–335, 2002. © 2002 Wiley‐Liss, Inc.
77Se,19F 2D NMR correlation spectroscopy of fluoro(organylseleno)alkenes and ‐alkanes
Authors: Poleschner Helmut , Seppelt Konrad
Published: November 2002

77Se,19F{1H} shift correlated two‐dimensional NMR measurements on mixtures of organofluoroselenium compounds are presented for assignment of the 77Se and 19F resonances. The regioisomeric fluoro(phenylseleno)alkenes BuCFC(SePh)R and RCFC(SePh)Bu with R = Me, Et and nPr and the diastereomeric pair EtCHFCH(SeAr*)Et with a chiral aryl group Ar* and PhSeCHCF2 were investigated as model compounds. 77Se,19F correlation peaks resulting from J(Se,F) coupling constants from 41 down to 4 Hz were measured. Copyright © 2002 John Wiley & Sons, Ltd.
Performance of timber buildings under high wind loads
Authors: Rosowsky David V
Published: November 2002

Timber structures often represent the largest percentage of structures built in regions at greatest risk of hurricanes and other high wind events. In countries in which wood structures are common, they often comprise the majority of residential, light commercial, and other low‐rise structures. This paper addresses some of the important issues in the performance of wood buildings subject to high wind loads. Implications for design are addressed and recent and on‐going research is discussed. Developments in the codes and standards areas and future research directions also are discussed.
Entrainment vortices and interfacial intermittent
turbulent bulges in a plane turbulent wake
Authors: KOPP GREGORY A. , GIRALT FRANCESC , KEFFER JAMES F.
Published: October 2002

Hot-wire measurements were made simultaneously in two homogeneous ‘horizontal’
planes in the far-wake region of a cylinder. A technique developed using hot-wire
data to identify the spatial characteristics of the large-scale bulges at the interface
between the internal turbulent motions and the external irrotational flow was used to
unambiguously relate these outer intermittent bulges to the inner coherent structures.
It was found that a turbulent bulge is made up of a combination of a horseshoe
vortex (whose legs form one double-roller eddy) and the straining region present just
upstream of this structure. The approach also allowed the evaluation of the two most
prominent phenomenological models for the entrainment mechanism in the far-wake
region: the Kelvin–Helmholtz instability and Townsend's growth–decay cycle. It was
found that the decaying and re-forming of the bulges and entrainment structures is
not likely to occur. Rather, the evidence is that the large-scale bulges remain coherent
for long streamwise distances in equilibrium with the overall similarity of the flow.
Cambridge composition
Authors: Ray Nicholas
Published: October 2002

The nature of architectural design in the early twenty-first century
is considered through a comparison between the author's recent
design for a university hostel and earlier examples of the genre.

This project was designed by a Lecturer in
Architecture at Cambridge for one of its Colleges. It is
occupied by undergraduates, some of them
architecture students, and during its construction it
was used as a teaching case study. The design is
somewhat ‘didactic’ in nature, attempting to be
quite explicit in its thematic and formal procedures;
stylistically, it can be seen as an examination of the
possibilities inherent in a late modernist tradition.
For this reason, and because of its privileged site and
budget, it offers an opportunity for some reflections
on architectural composition at the beginning of the
twenty-first century, in relation to earlier traditions
of formal manipulation.
Sigurd Lewerentz: Church of St Peter, Klippan, 1963–66
Authors: Blundell Jones Peter
Published: November 2002

This modest building questions basic assumptions about processes
and finishes, about the nature of brickwork and the detailing of
window frames – and provides a powerful space for worship.
RhoA kinase and protein kinase C participate in regulation of rabbit stomach fundus smooth muscle contraction
Authors: Ratz Paul H , Meehl Joel T , Eddinger Thomas J
Published: November 2002

The degree to which the RhoA kinase (ROK) blockers, Y‐27632 (1 μM) and HA‐1077 (10 μM), and the PKC blocker, GF‐109203X (1 μM), reduced force produced by carbachol, a muscarinic receptor agonist, and phenylephrine, an α‐adrenoceptor agonist, was examined in rabbit stomach fundus smooth muscle.

When examining the effect on cumulative carbachol concentration‐response curves (CRCs), ROK and PKC blockers shifted the potency (EC50) to the right but did not reduce the maximum response.

In a single‐dose carbachol protocol using moderate (∼EC50) and maximum carbachol concentrations, Y‐27632 and HA‐1077 reduced peak force, but GF‐109203X had no effect. By contrast, all three agents inhibited the carbachol contractions of rabbit bladder (detrusor) smooth muscle.

Compared to carbachol, phenylephrine produced a weaker maximum response that was not inhibited by phentolamine, atropine nor capsaicin but was inhibited by Y‐27632, HA‐1077 and GF‐109203X.

In detrusor, classical down‐regulation occurred, but in fundus, up‐regulation of responsiveness occurred. This up‐regulation in fundus may have been a post‐receptor event, because a KCl‐induced contraction produced after a carbachol CRC was stronger than one produced before the carbachol stimulus.

In conclusion, these data suggest that ROK plays a critical role in the regulation of rabbit fundus smooth muscle contraction, which is distinct from chicken gizzard smooth muscle, where ROK is reported to exist but to not play a role in muscarinic receptor‐induced contraction. Additional unique findings are that PKC participates in phenylephrine‐ but not carbachol‐induced contraction in fundus, that carbachol does not activate identical subcellular signalling systems in fundus and detrusor, and that fundus, unlike detrusor, responds to carbachol stimulation with post‐receptor up‐regulation of contraction.

British Journal of Pharmacology (2002) 137, 983–992. doi:10.1038/sj.bjp.0704952
Functional consequences of perinatal exposure to3,4‐methylenedioxymethamphetamine in rat brain
Authors: Kelly Paul A T , Ritchie Isobel M , Quate Linda , McBean Douglas E , Olverman Henry J
Published: November 2002

In this study we have examined methylenedioxymethamphetamine (MDMA)‐induced toxicity in perinatal rat brain, related this to normal development of serotonin transporter sites (SERT), and determined whether early exposure to MDMA subsequently alters cerebral function in adults.

Perinatal development of SERT was visualized and quantified using [3H]‐paroxetine binding autoradiography in embryonic and neonatal rat brain from embryonic day 15 (E15) to postnatal day 30 (P30). Cerebral glucose utilization (lCMRglu) was measured by 2‐deoxyglucose autoradiography in adult rats.

[3H]‐Paroxetine binding was observed in forebrain from E18. From birth (P0), binding was organized into neocortical columns (75% higher at P10 than in adult) which declined toward adult levels between P20 and P25.

MDMA treatment (20 mg kg−1 s.c. twice daily for four days) commencing at developmental stages from E15 (treatment given to dams) to P20, had no effect upon [3H]‐paroxetine binding measured at P40. Treatments started on P25 or later resulted in significant decreases in [3H]‐paroxetine binding (46%). This was coincident with the development of adult patterns of binding in forebrain.

Despite the lack of MDMA‐induced neurotoxicity, rats treated in utero (E15) showed increased lCMRglu in locus coeruleus (+37%), and in areas receiving ascending noradrenergic innervation, such as anterior thalamus (+44%) and septal nucleus (+24%).

These studies confirm that the susceptibility of serotonergic terminals to the neurotoxic properties of MDMA is absent in the immediate perinatal period, but also suggests that in utero MDMA exposure produces significant long‐term effects on cerebral function by a mechanism as yet unknown.

British Journal of Pharmacology (2002) 137, 963–970. doi:10.1038/sj.bjp.0704961
Presentation of antagonist peptides to naive CD4+T cells abrogates spatial reorganization of class II MHC peptide complexes on the surface of dendritic cells
Authors: Chmielowski Bartosz , Pacholczyk Rafal , Kraj Piotr , Kisielow Pawel , Ignatowicz Leszek
Published: November 2002

By using dendritic cells (DCs) transduced with retroviruses encoding covalent Abβ/peptide fusion proteins tagged with fluorescent proteins, we followed the relocation of class II MHC molecules loaded with agonist or null peptides during the onset of activation of naive and effector CD4+T cells. Clusters of T cell receptor (TCR)/CD3 complex formed in parallel with clusters of agonist class II MHC/peptide complexes on the surface of DCs. However, activation of naive but not effector T cells was accompanied by expulsion of the null class II MHC/peptide complexes from the T cell–DC interface. These effects were perturbed in the presence of exogenously supplied antagonist peptide. These results suggest that interference with selective relocation of agonist and null MHC/peptide complexes in the immunological synapse contributes to the inhibitory effect of antagonist peptides on the response of naive CD4+T cells to agonist ligands.
Replicating hepatitis delta virus RNA is edited in the nucleus by the small form of ADAR1
Authors: Wong Swee Kee , Lazinski David W.
Published: November 2002

Hepatitis delta virus (HDV) uses a host-encoded RNA-editing activity to express its two essential proteins from the same coding sequence. Adenosine deaminase that acts on RNA (ADAR)1 and ADAR2 are enzymes that catalyze such reactions, and each, when overexpressed, are capable of editing HDV RNA
in vivo
. However, the enzyme responsible for editing HDV RNA during replication has not been determined. Mammalian cells express two forms of ADAR1, a large form (ADAR1-L) that mainly localizes to the cytoplasm and a small form (ADAR1-S) that resides in the nucleus. Recently, we found that the specific activity of ADAR1-L within cells is much higher than that of ADAR1-S but only when the substrate can be edited in the cytoplasm. Here we observed that although both ADAR1-S and ADAR1-L were expressed throughout HDV replication, no ADAR2 could be observed at any time. Using expression vectors that individually overexpress either form of ADAR1, we found that ADAR1-S could stimulate editing during replication more efficiently. We next reduced ADAR1 levels during HDV replication. After transfection of an ADAR1-L-specific small interfering RNA (siRNA), we observed a significant loss of that protein and its associated cytoplasmic editing activity while the level of ADAR1-S remained unchanged. Transfection of this siRNA, however, did not reduce editing during HDV replication. In contrast, transfection of an siRNA that targets both forms of ADAR1 greatly reduced the expression of both proteins and potently inhibited editing during replication. We conclude that ADAR1-S edits HDV RNA during replication and that editing occurs in the nucleus.
Time-lapse imaging of a dynamic phosphorylation-dependent protein–protein interaction in mammalian cells
Authors: Spotts James M. , Dolmetsch Ricardo E. , Greenberg Michael E.
Published: November 2002

The ability to make sensitive measurements of protein–protein interaction kinetics in single neurons is critical for understanding the molecular and cellular basis of neuronal function. We have developed a reporter technology based on the differential induction of
Escherichia coli
TEM-1 β-lactamase (Bla) enzymatic activity that can function as a sensor of the interaction state of two target proteins within single neurons
in vivo
. To modulate Bla enzymatic activity, we first split the enzyme into two separate, complementary protein fragments that we identified by using a functional screening approach based on circular permutation of the Bla enzyme. The split enzyme was then brought together by the phosphorylation-dependent association of the kinase inducible domain of the cAMP response element binding protein (CREB) and the KIX domain of the CREB binding protein. Using an intracellular substrate whose fluorescence spectrum changes after hydrolysis by Bla, we performed time-lapse ratiometric imaging measurements of Bla enzymatic induction after association of the CREB and CREB binding protein interaction domains. This approach permits direct imaging of protein–protein interactions in single cells with high signal discrimination.
Ammonia Pulses and Metabolic Oscillations Guide Yeast Colony Development
Authors: Palková Zdena , Devaux Frédéric , R̆ic̆icová Markéta , Mináriková Lucie , Le Crom Stéphane , Jacq Claude
Published: November 2002

On solid substrate, growing yeast colonies alternately acidify and alkalinize the medium. Using morphological, cytochemical, genetic, and DNA microarray approaches, we characterized six temporal steps in the “acid-to-alkali” colony transition. This transition is connected with the production of volatile ammonia acting as starvation signal between colonies. We present evidence that the three membrane proteins Ato1p, Ato2p, and Ato3p, members of the YaaH family, are involved in ammonia production in Saccharomyces cerevisiae colonies. The acid-to-alkali transition is connected with decrease of mitochondrial oxidative catabolism and by peroxisome activation, which in parallel with activation of biosynthetic pathways contribute to decrease the general stress level in colonies. These metabolic features characterize a novel survival strategy used by yeast under starvation conditions prevalent in nature.
THE COSMOLOGICAL DOUBT
Authors: TRIAY ROLAND
Published: November 2002

The present paper is a polemic which describes how Inflation came on the scene and suggests a possible alternative.
NONPLANAR CONTRIBUTION TO THE EFFECTIVE ACTION IN NONCOMMUTATIVE FLAT MANIFOLDS
Authors: BYTSENKO A. A. , CHAVES F. M. P. , GONÇALVES A. E.
Published: November 2002

The nonplanar contribution to the effective action for massless scalar and vector fields on D– dimensional manifold with p compact noncommutative extra dimensions is calculated. The zeta function may not be regular at the origin. Thus, the related heat kernel trace has a logarithmic term in the short t asymptotic expansion. Consequences of this fact are briefly discussed.
Genetic Mating Systems and Reproductive Natural Histories of Fishes: Lessons for Ecology and Evolution
Authors: Avise John C. , Jones Adam G. , Walker DeEtte , DeWoody J. Andrew ,   collaborators
Published: November 2002

▪ Abstract  Fish species have diverse breeding behaviors that make them valuable for testing theories on genetic mating systems and reproductive tactics. Here we review genetic appraisals of paternity and maternity in wild fish populations. Behavioral phenomena quantified by genetic markers in various species include patterns of multiple mating by both sexes; frequent cuckoldry by males and rare cuckoldry by females in nest-tending species; additional routes to surrogate parentage via nest piracy and egg-thievery; egg mimicry by nest-tending males; brood parasitism by helper males in cooperative breeders; clutch mixing in oral brooders; kinship in schooling fry of broadcast spawners; sperm storage by dams in female-pregnant species; and sex-role reversal, polyandry, and strong sexual selection on females in some male-pregnant species. Additional phenomena addressed by genetic parentage analyses in fishes include clustered mutations, filial cannibalism, and local population size. All results are discussed in the context of relevant behavioral and evolutionary theory.
CD14-Deficient Mice Are Protected Against Lipopolysaccharide-Induced Cardiac Inflammation and Left Ventricular Dysfunction
Authors: Knuefermann Pascal , Nemoto Shintaro , Misra Arunima , Nozaki Naoki , Defreitas Gilberto , Goyert Sanna M. , Carabello Blase A. , Mann Douglas L. , Vallejo Jesus G.
Published: November 2002

Background—

The molecular mechanisms responsible for sepsis-induced myocardial dysfunction remain undefined. CD14 mediates the inflammatory response to lipopolysaccharide (LPS) in various organs including the heart. In this study we investigated the role of CD14 in LPS-induced myocardial dysfunction in vivo.

Methods and Results—

Wild-type and CD14-deficient (CD14-D) mice were challenged with
Escherichia coli
LPS. Myocardial tumor necrosis factor, interleukin-1β (IL-1β), and NOS2 induction was measured before and 6 hours after LPS challenge. Echocardiographic parameters of left ventricular function were measured before and 6 hours after LPS administration. LPS challenge induced a significant increase in myocardial tumor necrosis factor and IL-1β mRNA and protein expression in wild-type mice. In contrast, mRNA and protein levels for TNF and IL-1β were significantly blunted in CD14-D mice. An increase in NOS2 protein was noted within 6 hours of LPS provocation only in the hearts of wild-type mice. This was associated with an increase in ventricular cGMP levels. Activation of nuclear factor-κB was observed within 30 minutes of LPS in the hearts of wild-type mice but not in CD14-D mice. In wild-type mice, LPS significantly decreased left ventricular fractional shortening, velocity of circumferential shortening, and dP/dt
max
. LPS-treated CD14-D mice maintained normal cardiac function.

Conclusions—

These results suggest that CD14 is important in mediating the proinflammatory response induced by LPS in the heart and that CD14 is necessary for the development of left ventricular dysfunction during LPS-induced shock in vivo.
Toughening of polypropylene with styrene/ethylene‐butylene/styrene tri‐block copolymer: Effects of reactive and nonreactive compatibilization
Authors: Bassani A. , Pessan L. A.
Published: October 2002

The effects of compatibilization on the toughening of polypropylene (PP) by melt blending with styrene/ethylene‐butylene/styrene tri‐block copolymer (SEBS) in a twin‐screw extruder were investigated. The compatibilizers used were SEBS functionalized with maleic anhydride (SEBS‐g‐MA), PP functionalized with acrylic acid (PP‐g‐AA), and bifunctional compound p‐phenylenediamine (PPD). The effects of the compatibilization were evaluated through the mechanical properties as well as through the determination of the phase morphology of the blends by scanning electron microscopy. Reactive compatibilized blends show up to a 30‐fold increase in impact strength compared with neat PP; likely the result of the reaction of the bifunctional compound (PPD) with the acid acrylic and maleic anhydride groups, this increase in strength rendered both morphological and mechanical stability to these blends. The addition of PPD to the blends significantly changed their phase morphologies, leading to larger average diameters of the dispersed particles, probably as a result of the morphological stabilization at the initial processing steps during extrusion, with the occurrence of chemical reactions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3466–3479, 2002
Synthesis and characterization of liquid crystalline polymers containing aromatic ester mesogen and a nonmesogenic ferrocene unit in the spacer
Authors: Kannan P. , Senthil S. , Vijayakumar R. , Marimuthu R.
Published: October 2002

A new series of liquid crystalline polymers containing aromatic triad ester mesogen and 1,1′‐disubstituted ferrocene as a nonmesogenic unit along with polymethylene spacer was synthesized. The polymer was synthesized by a room temperature polycondensation reaction between bis(4‐chloroformyl phenyloxy alkyl ferrocene dicarboxylate) and quinol. The alkyl groups have been varied by an even number of methylene groups with a range from two to ten groups. All the polymers were found to possess liquid crystalline properties. The identification of the mesophase is more transparent with an increase in the spacer. The thermal characteristics were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the thermal stability of the polymers was decreased with increasing spacer length. The Tg, Tm, and Ti of the polymers decreased with increasing methylene groups. The incorporation of the ferrocene moiety also has a considerable effect on the glass transition temperature. The char yield of the polymer decreases with an increasing methylene chain length. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3494–3501, 2002
Preparation of soluble copolyurethaneimide containing oxyethylene and oxypropylene units
Authors: Kim In‐Chul , Kim Jong‐Ho , Lee Kew‐Ho , Tak Tae‐Moon
Published: October 2002

Soluble copolyurethaneimides were synthesized by the isocyanate method in a solution of N‐methyl‐2‐pyrrolidone (NMP). The isocyanate‐terminated prepolyurethane prepared from low molecular weight poly(ethylene glycol) (PEG) or poly(propylene glycol) (PPG) and methylene diisocyanate was reacted with pyromellitic dianhydride at high temperature. The resulting copolyurethaneimides were soluble in polar solvents like N‐methyl‐2‐pyrrolidone and N,N'‐dimethylformamide. The film‐forming properties were investigated by changing the molecular weights of PEG and PPG. With PPG, the film‐forming property was enhanced. The inherent viscosity, solubility, thermal property, molecular weight distribution, and mechanical property were compared with the aromatic polyimide. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3502–3507, 2002
Preparation of polymer/silica nanoscale hybrids through sol‐gel method involving emulsion polymers. II. Poly(ethyl acrylate)/SiO2
Authors: Tong Xin , Tang Tao , Feng Zhiliu , Huang Baotong
Published: October 2002

Poly(ethyl acrylate) (PEA)/SiO2 hybrids with different compositions were prepared under different casting temperatures and pH values. Their morphology as investigated by transmission electron microscopy (TEM) shows that samples with different compositions have different morphologies. When the SiO2 content is lower, PEA is the continuous phase and SiO2 is the dispersed phase. At higher SiO2 content, the change in phase morphology takes place, nd PEA gradually dispersing in the form of latex particles in SiO2 matrix. Change in phase morphology depends mainly on the time the sol‐gel transition occurs. At suitable casting temperature and pH value, PEA/SiO2 in 95/5 and 50/50 hybrids with even dispersion was obtained. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3532–3536, 2002
Real‐time temperature and photon transmission measurements for monitoring phase separation during the formation of poly(N‐isopropylacrylamide) gels
Authors: Kara Selim , Okay Oguz , Pekcan Onder
Published: October 2002

Phase separation during the formation of poly(N‐isopropylacrylamide) (PNIPA) hydrogels was investigated using real‐time photon transmission and temperature measurements. The hydrogels were prepared by free‐radical crosslinking polymerization of N‐isopropylacrylamide (NIPA) in the presence of N,N′‐methylenebisacrylamide (BAAm) as a crosslinker in an aqueous solution. The onset reaction temperature T0 was varied between 20 and 28°C. Following an induction period, all the gelation experiments resulted in exothermic reaction profiles. A temperature increase of 6.5 ± 0.6°C was observed in the experiments. It was shown that the temperature increase during the formation and growth process of PNIPA gels is accompanied by a simultaneous decrease in the transmitted light intensities Itr. The decrease in Itr at temperatures below the lower critical solution temperature of PNIPA was explained by the concentration fluctuations due to the inhomogeneity in the gel network. At higher temperatures, it was shown that the gel system undergoes a phase transition via a spinodal decomposition process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3589–3595, 2002
Effect of plant gums on thermal polymerization of acrylonitrile
Authors: Jana S. C. , Maiti S. , Sengupta P. K. , Biswas S.
Published: October 2002

The effect of some plant gums on the polymerization of acrylonitrile (AN) using ceric ammonium nitrate (CAN) as an initiator in the presence of air (containing 21% oxygen) was studied. The induction period and percent conversion were determined. The induction period in the presence of gum was comparatively lower than that under a N2 atmosphere. The rate of polymerization has a 1.5‐power dependence on the monomer concentration and the rate is sufficiently high at moderate temperature. The rate also increased with an increasing initiator concentration and reaches a maximum value of 93% at 0.72 × 10−2 mol L−1 of CAN. The activation energy was found to be 6.4 kcal mol−1. Both the molecular weight and density of the polyacrylonitrile (PAN) prepared in the presence of gum were higher than those of PAN prepared in the absence of the gum. The PAN produced in the presence of the gum was thermostable than that prepared in its absence. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3596–3600, 2002
Analysis of physical properties of PET/CD‐PET polyblend hollow fiber and its kinetics of alkaline hydrolysis
Authors: Hsiao Kai‐Jen , Jen Zhi‐Feng , Lu Cheng‐Liang
Published: October 2002

Cationic dyeable poly(ethylene terephthalate) (CD‐PET) was formed by copolymerizing dimethylterephthalate (DMT),5‐sodium sulfonate dimethyl isophthalate (SIPM) with a molar ratio of 2% and ethylene glycol (EG). Blends of regular poly(ethylene terephthalate) (PET) and CD‐PET were spun into hollow fibers. The fibers were then treated with aqueous NaOH. This study investigated the physical properties of PET/CD‐PET polyblend hollow fibers and their kinetic behavior of alkaline hydrolysis using differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), the density gradient method, a gel permeation chromatograph (GPC), a rheometer, and regression analysis of the statistical method. For the alkaline hydrolysis kinetics equation of PET, CD‐PET, and PET/CD‐PET polyblend materials: − dW/dt = KCαAβ, β values of chip and POY/ FOY hollow fibers are equal to 1. Moreover, R2 of the kinetics equation of chip/POY/FOY for a from 1.09–1.35/1.08–1.32/1.06–1.29 were better than those of a = 1. Experimental results indicate that the rate constant of alkaline hydrolysis was CD‐PET hollow fiber > PET/CD‐PET polyblend hollow fibers > PET hollow fiber and FOY > POY > > Chip. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3601–3610, 2002
Characterization of an amorphous surface layer on blown polyolefin film
Authors: Chang A. C. , Chum S. P. , Hiltner A. , Baer E.
Published: October 2002

This study concerned an amorphous surface layer on blown polyethylene film with a composition different from that of the bulk. The surface layer was characterized by gentle probing with an atomic force microscope. The demonstration of an amorphous layer uniformly covering the surface of a blown Ziegler–Natta‐catalyzed polyethylene (znPE) film reproduced previous reports. Removing the surface layer by solvent washing confirmed the hypothesis that the layer consisted of lower molecular weight, higher branch content fractions. A blown film of znPE blended with up to 30 wt % impact‐modified high‐melt‐strength polypropylene (hmsPP) also exhibited an amorphous surface layer. In thin films, it was advantageous for the mobile, amorphous fractions of ethylene–propylene rubber (EPR) to locate at the surface rather than at the phase interface. The amorphous EPR tended to segregate into pools on the film surface, and this pointed to a substantial difference between the amorphous surface layers on the znPE and hmsPP/znPE blend films. Surface enrichment best described the compositional gradient that resulted from the concentration of lower molecular weight, higher branch content chains at the surface of the znPE film. Surface segregation was more appropriate for the emergence of EPR fractions as a separate phase on the surface of the hmsPP blend film. Films blown from a blend of a Ziegler–Natta‐catalyzed polyethylene and a metallocene‐catalyzed polyethylene (zn/mPE) and its blend with hmsPP reproduced the primary features of surface enrichment and surface segregation. Some differences between the znPE and zn/mPE films were attributed to the metallocene constituent of zn/mPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3625–3635, 2002
Block copolyesters of poly(pentamethylene 2,6‐naphthalenedicarboxylate) and poly(tetramethylene adipate)
Authors: Tsai Ruey‐Shi , You Jiang‐Wen , Lee Yu‐Der , Tsai Hong‐Bing
Published: October 2002

Hydroxy‐terminated poly(pentamethylene 2,6‐naphthalenedicarboxylate) oligomers were prepared by melt polycondensation of dimethyl 2,6‐naphthalenedicarboxylate with excess 1,5‐pentanediol followed by evacuating out some 1,5‐pentanediol. The molecular weight of the poly(pentamethylene 2,6‐naphthalenedicarboxylate) oligomers was controlled by the charge molar ratio of 1,5‐pentanediol to dimethyl 2,6‐naphthalenedicarboxylate and the amount of 1,5‐pentanediol removed under vacuum. The 1H‐NMR spectra of the poly(pentamethylene 2,6‐naphthalenedicarboxylate) oligomers indicate that the transesterification between dimethyl 2,6‐naphthalenedicarboxylate and 1,5‐pentanediol was almost complete. Block copolyesters with hard segments of poly(pentamethylene 2,6‐naphthalenedicarboxylate) and soft segments of poly(tetramethylene adipate) were prepared by coupling the poly(pentamethylene 2,6‐naphthalenedicarboxylate) oligomer and a poly(tetramethylene adipate) glycol with methylene‐4,4′‐diphenylene diisocyanate in solution. The block copolyesters were characterized by IR, 1H‐NMR, DSC, and X‐ray diffraction. The hard segments in the block copolyesters display an amorphous state. However, the thermal transitions of soft segments in the block copolyesters are strongly dependent on the composition. When the content of the hard segments increases, the glass transition temperature of the soft segments increases. Thus, the amorphous parts of the soft segments would be partially miscible with the hard segments. When the content of the hard segments is very low, the soft segments of the block copolyesters exhibit high crystallinity. But, as the content of the hard segments is about 30 wt % or more, the soft segments of the block copolyesters become amorphous. This is described as the effect of the presence of the hard segments which are partially miscible with the soft segments. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3652–3659, 2002
Effects of microstructures on the viscoelastic and rheological properties of metallocene‐catalyzed cyclo‐olefin copolymers: A preliminary study
Authors: Shih Hsi‐Hsin , Shiao Po‐Ling , Hsu Hsiu‐Chin , Liu Hsin‐Ju , Huang Chi‐Jou , Tsai Chin‐Chin
Published: October 2002

We characterized metallocene‐catalyzed cyclo‐olefin copolymers (mCOCs) with similar heat distortion temperatures but dramatic differences in melt‐flow indices to understand how the molecular conformation affected their rheological and viscoelastic properties. The mCOC conformations were identified with 13C‐NMR, whereas the viscoelastic and rheological properties were measured with cone‐and‐plate and high‐pressure capillary rheometers. Our preliminary results showed that the mCOC rheological and viscoelastic properties might depend strongly on the conformation rather than the norbornene content, molecular weight, and molecular weight distribution. mCOCs containing ‐NNN‐ locks (where N represents norbornene) exhibited stronger molecular entanglements than those having no ‐NNN‐ blocks, as reflected in lower crossover frequencies and higher crossover torque. Furthermore, the existence of larger rigid ‐NNN‐ blocks resulted in higher molten viscosities and flow activation energies. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3695–3701, 2002
Surface characteristics of water‐soluble cationic fluoro copolymers containing perfluoroalkyl, quaternized amino, and hydroxyl groups
Authors: Lee Chang‐Yong , Ha Jong‐Wook , Jun Park In , Lee Soo‐Bok
Published: October 2002

Various water‐soluble cationic fluoro copolymers in quaternized form with perfluoroalkyl, amino, and hydroxyl groups were prepared by varying the contents of perfluoroalkyl ethyl acrylate (FA), 2‐(dimethylamino) ethyl methacrylate (DAMA), and 2‐hydroxyethyl methacrylate (HEMA). The solvent polymerization was carried out in acetone, with the subsequent addition of acetic acid to form a quaternized polymer. Polyurethanes films were prepared by curing aqueous solutions containing water‐soluble cationic fluoro copolymers and a blocked isocyanate at 190°C. The surface characteristics of the water‐soluble cationic fluoro copolymers and the polyurethanes were investigated on the basis of FA and DAMA contents. The contact angles for both water and methylene iodide (MI) on the cationic fluoro copolymer and the polyurethane increase steadily as FA content increases, and decrease gradually with increasing DAMA content. The contact angles on the polyurethane are slightly higher than those on the cationic fluoro copolymer. The cationic fluoro copolymer and the polyurethane with FA content of 40 wt % and DAMA content of <30 wt % show extremely low surface free energies of 13–15 dynes/cm. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3702–3707, 2002
Synthesis and structure of polymethylsilsesquioxane–clay nanocomposite via in situ intercalative polymerization
Authors: Ma Jun , Shi Lianghe , Yang Mingshu , Li Baiyu , Liu Haiyun , Xu Jian
Published: October 2002

Polymethylsilsesquioxane (PMSQ)–montmorillonite (MMT) nanocomposites were prepared by in situ intercalative polymerization. The dispersion of the MMT layers within the matrix was verified by X‐ray diffraction and transmission electron microscopy, which revealed an intercalated morphology with layer spacing of 3.42 nm. The layer spacing was not increased after annealing at 150°C for 3 h. The reason for this result is explained in light of the molecular structure of PMSQ synthesized in and out of the nanoconfined environment. The coherent order of the silicate layer was decreased after the annealing, possibly because of the change in the PMSQ molecule during the annealing process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3708–3711, 2002
Study on foaming water‐swellable EPDM rubber
Authors: Sun Xiaohong , Zhang Guo , Shi Qiang , Tang Benchen , Wu Zhongwen
Published: October 2002

A foaming ethylene propylene diene terpolymer (EPDM) water‐swellable rubber (WSR) was prepared using the multicomponent mechanical blending technology. The morphology of unfilled and silica‐filled foaming EPDM WSR was studied from micrographs. The average cell size, maximum cell size, and cell density of the foaming WSR had a peak value with a 4‐phr foaming agent loading in both unfilled and silica‐filled WSR. The addition of silica made the average cell size and maximum cell size decrease and the cell uniform. With incorporation of silica, the tensile strength of the unfoaming WSR increased three times, while that of the foaming WSR increased about six times before immersing it into water. After water‐swelling, the mechanical properties of both the unfilled WSR and silica‐filled unfoaming WSR decreased, but that of the silica‐filled foaming WSR increased. The silica filler accelerated the water‐swelling rate and cut down the water‐swelling equilibrium time at the same time. The foaming WSR had a better volume water‐swelling ratio than that of the unfoaming WSR in both the unfilled and silica‐filled WSR. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3712–3717, 2002
Moisture absorption behavior of rubber‐modified epoxy resins
Authors: Lin King‐Fu , Yeh Ren‐Jie
Published: October 2002

The moisture absorption behavior of diglycidyl ether of bisphenol A/ethylene diamine resins incorporating a carboxy‐terminated butadiene–acrylonitrile rubber was investigated and associated with their morphology of phase separation. Although the diffusion coefficient of moisture was increased with the rubber content, its activation energy and free volume for moisture diffusion were barely changed until phase inversion occurred. After phase inversion, the free volume was significantly increased, and the activation energy decreased. In addition, the moisture absorption also reduced the β‐transition temperature of the resins and slightly increased the glass‐transition temperature before phase inversion. However, the reverse was found after phase inversion. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3718–3724, 2002
Networks of photocrosslinked poly(meth)acrylates in linear poly(vinyl chloride)
Authors: Kaczmarek Halina , Ołdak Dagmara , Szalla Aleksandra
Published: October 2002

Five different multifunctional acrylic monomers (trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and dipentaerythritol pentaacrylate) were photopolymerized alone or in a matrix of linear poly(vinyl chloride) (PVC) with 2,2‐dimethyl‐2‐hydroxyacetophenone as a photoinitiator. The course of photopolymerization was estimated with Fourier transform infrared spectroscopy. The amount of insoluble gel formed during photopolymerization was determined gravimetrically. The crosslinked polymerization of pure monomers was much faster than that in the presence of PVC. However, the efficiency of the reaction was higher when it was carried out in a PVC blend because of the higher mobility of the propagating macroradicals. The influence of the monomer structure and functionality on the polymerization course was examined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3725–3734, 2002
Evidence that thermodynamic stability of papaya glutamine cyclase is only marginal
Authors: Azarkan Mohamed , Amrani Amina , Zerhouni Samira , Oberg Keith A. , Ruysschaert Jean‐Marie , Wintjens René , Looze Yvan
Published: October 2002

Papaya glutamine cyclase (PQC), a glycoprotein with a molecular mass of 32,980 Da, is a minor constituent of the papaya latex protein fraction. In neutral aqueous solutions, PQC adopts an all‐β conformation and exhibits high resistance to both proteolysis and denaturation. Complete unfolding of PQC requires a combination of an acidic medium and chemical denaturant such as urea or guanidine hydrochloride. The unfolding process takes place through formation of an intermediate A state that accumulates in the absence of chemical denaturants and displays all the features of a molten globule state. The different conformational states—N (native), A (acid‐inactivated), and U (unfolded)—have been characterized by means of circular dichroism measurements, fluorescence spectroscopies, Stokes radii determinations, and 8‐anilino‐1‐naphtalenesulfonic acid (ANS) binding characteristics. The unfolding pathways of the enzyme was further studied to estimate thermodynamic parameters characterizing both transitions N ⇔ A and A ⇔ U. In its A state, PQC is catalytically inefficient and highly susceptible to proteolysis. Also, its thermodynamic stability is decreased by some 3–5 kcal/mol. Conversion of the native to the A state involves digging up of five amino functions together with protonation of four to five acidic groups with pKas, in the native state, around 2.7. It proceeds both cooperatively and reversibly although, in vitro, the refolding process is slow. Unfolding of the A state, on the other hand, occurs with a low degree of cooperativity. The intermediate A state thus seems to be only marginally more stable than the unfolded state. The role of suspected internal ion pairs in the stabilization of the native state of this enzyme is discussed. © 2002 Wiley Periodicals, Inc. Biopolymers 65: 325–335, 2002
The ribbon of hydrogen bonds and the pseudomolecule in the three‐dimensional structure of globular proteins. III. Bovine pancreatic ribonuclease A and bovine seminal ribonuclease
Authors: Peters David , Peters Jane
Published: October 2002

The model of the three‐dimensional structure of globular proteins, which is based on a ribbon of hydrogen bonds along the whole of the backbone, is now applied to the comparison between monomeric bovine pancreatic ribonuclease A and dimeric bovine seminal ribonuclease. Some waters are involved in the hydrogen bonding of the ribbon, and the protein molecule plus these waters forms a pseudomolecule. The conformations of the three backbones are essentially identical and the three ribbons of hydrogen bonds are conserved with greater than 90% accuracy. We suggest that the conservation of the backbone conformations of the two molecules is a consequence of the conservation of the ribbons of hydrogen bonds. There are 16 simple mutations between the two molecules, of which 15 involve only side‐chain groups with no more than one hydrogen bond to the backbone. Such mutations are not sufficient to change the ribbon of hydrogen bonds and hence there is no change in the backbone conformation. Generalizing this result, we suggest that the conservation of the ribbon is the reason why single point mutations rarely change the conformation of the backbone of the globular proteins. © 2002 Wiley Periodicals, Inc. Biopolymers 65: 347–353, 2002
Peptide conformational changes induced by tryptophan–phosphocholine interactions in a micelle
Authors: Neidigh Jonathan W. , Andersen Niels H.
Published: October 2002

Sodium dodecylsulfate (SDS) and dodecylphosphocholine (DPC) micelles are often used to mimic the membrane‐ or receptor‐bound states of peptides in NMR studies. From the present examination of a 26‐residue analog of exendin‐4 (TrEX4) by NMR and CD in water, aqueous 30% trifluoroethanol (TFE), and bound to both SDS and DPC micelles, it is clear that these two lipid micelles can yield very different peptide structures. The Trp‐cage fold (also observed in 30% TFE) is present when TrEX4 is bound to SDS micelles; however, tertiary structure is absent in the presence of DPC micelles. The loss of tertiary structure is attributed to an energetically favorable interaction (estimated as 2–3 kcal/mol) of the tryptophan side chain with the phosphocholine head groups. These dramatic structural differences suggest that care must be taken when using either SDS or DPC to mimic the membrane‐ or receptor‐bound states. © 2002 Wiley Periodicals, Inc. Biopolymers 65: 354–361, 2002