bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isothermal and nonisothermal crystallization kinetics of poly(ε‐caprolactone)/multi‐walled carbon nanotube composites
Authors: Wu Tzong‐Ming , Chen Erh‐Chiang 
Published: July 2006

AbstractDifferential scanning calorimeter (DSC) and polarized optical microscopy (POM) have been used to investigate the isothermal and nonisothermal crystallization behavior of poly(ε‐caprolactone) (PCL)/multi‐walled carbon nanotube (MWNT) composites. PCL/MWNT composites have been prepared by mixing the PCL polymer with carboxylic groups containing multi‐walled carbon nanotubes (c‐MWNTs) in tetrahydrofuran solution. Raman spectrum of c‐MWNT indicated the possible presence of carboxylic acid groups at both ends and on the sidewalls of the MWNTs. The TEM micrograph showed that the c‐MWNT is well separated and uniformly dispersed in the PCL matrix. DSC isothermal results showed that the introduction of c‐MWNT into the PCL initiates strongly heterogeneous nucleation, which induced a change of the crystal growth process. The activation energy of PCL significantly decreases by adding 0.25 wt% c‐MWNT into PCL/c‐MWNT composites and then increases as c‐MWNT content increases. The result demonstrates that the addition of c‐MWNT into PCL induces the heterogeneous nucleation at lower c‐MWNT content and then inhibits the polymer chain transportation ability during crystallization at higher c‐MWNT content. In this study, we have also studied the nonisothermal crystallization kinetics and melting behavior of PCL/c‐MWNT composites at various cooling rates. The correlation among isothermal and nonisothermal crystallization kinetics and melting behavior of PCL/c‐MWNT composites can be also discussed. POLYM. ENG. SCI., 46:1309–1317, 2006. © 2006 Society of Plastics Engineers
Facile syntheses of surface‐functionalized micelles and shell cross‐linked nanoparticles
Authors: O'Reilly Rachel K. , Joralemon Maisie J. , Hawker Craig J. , Wooley Karen L. 
Published: July 2006

AbstractBlock copolymer micelles and shell cross‐linked nanoparticles (SCKs) presenting Click‐reactive functional groups on their surfaces were prepared using two separate synthetic strategies, each employing functionalized initiators for the controlled radical polymerization of acrylate and styrenic monomers to afford amphiphilic block copolymers bearing an alkynyl or azido group at the α‐terminus. The first route for the synthesis of the azide‐functionalized nanostructures was achieved via sequential nitroxide‐mediated radical polymerization (NMP) of tert‐butyl acrylate and styrene, originating from a benzylic chloride‐functionalized initiator, followed by deprotection of the acrylic acids, supramolecular assembly of the block copolymer in water and conversion of the benzylic chloride to a benzylic azide. In contrast, the second strategy utilized an alkynyl‐functionalized reversible addition fragmentation transfer (RAFT) agent directly for the RAFT‐based sequential polymerization of tetrahydropyran acrylate and styrene, followed by selective cleavage of the tetrahydropyran esters to give the α‐alkynyl‐functionalized block copolymers. These Click‐functionalized polymers, with the functionality located at the hydrophilic polymer termini, were then self‐assembled using a mixed‐micelle methodology to afford surface‐functionalized “Clickable” micelles in aqueous solutions. The optimum degree of incorporation of the Click‐functionalized polymers was investigated and determined to be ca. 25%, which allowed for the synthesis of well‐defined surface‐functionalized nanoparticles after cross‐linking selectively throughout the shell layer using established amidation chemistry. Functionalization of the chain ends was shown to be an efficient process under standard Click conditions and the resulting functional groups revealed a more “solution‐like” environment when compared to the functional group randomly inserted into the hydrophilic shell layer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5203–5217, 2006
Erosion of multilayered films fabricated from degradable polyamines: Characterization and evidence in support of a mechanism that involves polymer hydrolysis
Authors: Zhang Jingtao , Fredin Nathaniel J. , Lynn David M. 
Published: July 2006

AbstractMultilayered polyelectrolyte assemblies fabricated using hydrolytically degradable polyamines (1–3) erode gradually when incubated in physiologically relevant media. This investigation sought to characterize physically and chemically the erosion of films fabricated from these polymers and sodium poly(styrene sulfonate) (SPS) and to investigate specifically the potential role of polymer hydrolysis in governing film erosion. The characterization of erosion using reflective infrared spectroscopy revealed changes in the carbonyl region of the spectrum that were consistent with the generation of polymer hydrolysis products. To evaluate the role of the esters in these materials more directly, we also synthesized a structural analogue of polymer 2 containing amide functionality rather than ester functionality. Assemblies fabricated from this amide‐containing polymer did not erode significantly or release SPS into solution when incubated in phosphate‐buffered saline (PBS). Finally, we characterized the erosion of assemblies fabricated from polymer 1 in PBS buffer prepared with D2O rather than H2O. These assemblies eroded significantly more slowly in deuterated media than in buffer prepared with H2O. These results, when combined, provide support for the view that polymer hydrolysis plays an important role in governing the erosion of assemblies fabricated from these degradable polymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5161–5173, 2006
Irreversibility line and critical current studies in κ‐(BEDT‐TTF)2Cu[N(CN)2]Br organic superconductor: effect of the structural transformation near 80 K
Authors: Tirbiyine A. , Senoussi S. , Taoufik A. , Ramzi A. , Haouam A. , Labrag A. 
Published: July 2006

AbstractWe report systematic magnetic measurements on organic superconductor κ‐(BEDT‐TTF)2Cu[N(CN)2]‐Br. The irreversibility line Hirr(T) and the critical current density Jc were studied. Our results show the strong dependence of Hirr(T) and Jc on the cooling rate. The Hirr(T) data follow power dependence H ∝ (1 – T /T c)m where m depends on the sample cooling. The structural transformation which occurs at the vicinity of 80 K influences very strongly the physics of vortex lattice and the associated magnetic behavior. This has a pronounced effect on the critical current density and the superconducting transition temperature Tc. Rapid cooling through 80 K will freeze the high temperature magnetic phase to low temperatures and the presence of local magnetic moments suppresses the superconducting Tc. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and magnetic characterization of GdSr2RuCu2O8 films deposited by d.c. sputtering
Authors: Guarino A. , Fittipaldi R. , Nigro A. , Gombos M. , Vecchione A. , Ciancio R. , Pace S. , Cimberle M. R. , Tropeano M. , Zola D. , Polichetti M. 
Published: July 2006

AbstractGdSr2RuCu2O8 oriented films have been deposited on SrTiO3 (100) substrate by d.c. sputtering. Films deposited in pure oxygen atmosphere have shown c‐axis oriented GdSr2RuCu2O8 phase after an appropriate ex‐situ thermal treatment in oxygen atmosphere. X‐ray diffraction, scanning electron microscopy and energy dispersive spectrometry have been used to check the crystal structure, the morphology and the composition of the samples. The investigations have been performed before and after the oxygen annealing pointing out an increased structural order.The samples have been characterized magnetically in the range from 1.9 to 400 K. A selected sample has exhibited a possible ferromagnetic transition with a Curie temperature of about 150 K. All the samples measured by transport measurements show a semiconducting behaviour down to 4.2 K. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystallographic and magnetic properties of a new rare‐earth iron nitride Nd2–xSmxFe17Ny (y ∼ 3)
Authors: Ben Kraiem M. S. , Cheikhrouhou A. 
Published: July 2006

AbstractThe effect of nitrogen insertion on the structural and magnetic properties of Nd2–xSmxFe17 metallic alloys has been investigated. X‐ray powder diffraction characterizations show that all the nitrides are single phase and crystallize in the Th2Zn17‐type structure. The lattice parameters of the Nd2–xSmxFe17Ny compounds decrease with samarium content. Magnetization studies show that all the samples are ferromagnetic at room temperature. Nitrogen insertion leads to an increase of the Curie temperature Tc. Tc is found to increase from 370 K for NdSmFe17 to 760 K for NdSmFe17N2.8. It leads also to an increase of the saturation magnetization Ms. $ { {{\rm M}_{\rm s}({\rm y}) - {\rm M}_{\rm s}(0)} \over {{\rm M}_{\rm s}(0)} } $ decreases with increasing samarium content from 58% for x = 0 to 45% for x = 2. X‐ray diffraction characterizations on magnetically aligned powder samples of Nd2–xSmxFe17Ny reveal a change in the easy magnetization direction from planar for x = 0 to c axis for x = 2. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Praseodymium deficiency effects on the physical properties of Pr1.2–x□xSr1.8Mn2O7 bilayer manganese oxides
Authors: Triki M. , Zouari S. , Cheikhrouhou A. , Strobel P. 
Published: July 2006

AbstractThe praseodymium deficiency effects on the structural, magnetic and electrical properties of the lacunar bilayers manganese oxides Pr1.2–x□xSr1.8Mn2O7 (0 ≤ x ≤ 0.15) were studied. Rietveld refinements of the X‐ray diffraction patterns show that all our samples are single phase and crystallize in the tetragonal structure with I4/mmm space group. All our samples exhibit a paramagnetic‐ferromagnetic transition on cooling. The praseodymium deficiency leads to a decrease of the Curie temperature. Resistivity measurements as a function of temperature show that only the parent sample Pr1.2Sr1.8Mn2O7 exhibits a semiconducting‐metallic transition with decreasing temperature. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charge distribution consequences of the magnetic order in TbB6
Authors: Galéra R. M. , Amara M. , Aviani I. , Givord F. , Zontone F. , Kunii S. 
Published: July 2006

AbstractThe antiferromagnetic state of TbB6 has been investigated by way of magnetostriction and X‐ray scattering measurements on a single crystal. The magnetostriction data reveal a well defined tetragonal symmetry lowering and a weak volume increase below TN . The X‐ray scattering investigation shows charge satellites, related to the 〈${1 \over 2}$00〉 and 〈${1 \over 2}$${1 \over 2}$0〉 wave vectors stars. The 〈${1 \over 2}$00〉 satellites are characteristic of exchange displacement waves, similar to those observed in GdB6, whereas the 〈${1 \over 2}$${1 \over 2}$0〉 ones could result as well from 4f multipolar scattering. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the magnetic properties and hyperfine fields in Fe‐containing alloys: A theoretical study
Authors: Samara Q. , Al‐Sharif A. I. , Mahmood S. H. 
Published: July 2006

AbstractIn this work, WIEN2k package has been used to calculate the structural and magnetic characteristics, and the hyperfine fields in a series of 1:1 ordered iron binary alloys and intermetallics FeT (T = Ti, V, Cr, Mn, Co, Ni). This is done by solving Kohn‐Sham equations using the Full‐Potential Linearized Augmented Plane Wave (FP‐LAPW) method. In the calculations, the Local Spin Density Approximation (LSDA) and the Generalized Gradient Approximation (GGA) were used for comparison. The results were compared with other theoretical and experimental measurements. Based on our results, GGA is found to be better than the LSDA in evaluating the hyperfine fields. Also the hyperfine fields in the ordered phases were found to be smaller than the hyperfine fields in the disordered phases of the studied systems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dipolar interaction, surface anisotropy and alloying effect on magnetic properties of the superlattice Ni1–xFex/Cu
Authors: Fahmi A. , Elharfaoui M. , Qachaou A. 
Published: July 2006

AbstractThe magnetic properties of superlattices Ni1–xFex/Cu are studied within the spin wave theory framework for 0 ≤ x ≤ 0.2 and x = 1. The excitation spectra and the magnetization are calculated using a Green's function method. The results show that for each wave vector value, there are N coupled planar modes for a superlattice with N planes. A competition between the effects of long‐range dipolar interaction and surface anisotropy is shown. The exchange and magnetic stability are reinforced when x increases. A comparison between the calculated and the measured magnetization under magnetic applied field gives a satisfactory estimation of the exchange integral values. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
U‐PVC gelation level assessment, part 1: Comparison of different techniques
Authors: Fillot Louise‐Anne , Hajji Philippe , Gauthier Catherine , Masenelli‐Varlot Karine 
Published: July 2006

AbstractSeveral different gelation assessment methods such as differential scanning calorimetry, capillary rheometry, solvent absorption, wide angle x‐ray scattering, transmission electron microscopy, and atomic force microscopy were applied to a typical PVC window profile formulation subjected to various thermomechanical histories. Shear applied during the process could be decomposed into two components: (i) a thermal component corresponding to the self‐heating that was generated and (ii) a “mechanical” component associated with a “pure” shearing action deprived of any thermal aspect. Shear sensitivity of the above‐mentioned gelation assessment techniques was evaluated by considering both aspects. Gelation levels established by differential scanning calorimetry and capillary rheometry were especially compared, thus allowing a comparison of the two physical aspects evidenced by each technique, i.e., crystallite melting and macromolecular network development. It appeared that as soon as the PVC particulate structure had been fragmented into micronic entities (primary particles) the gelation process was governed mainly by the thermal aspect, i.e., crystallite melting. J. VINYL. ADDIT. TECHNOL. 12:98–107, 2006. © 2006 Society of Plastics Engineers.
Degradation mechanism and mechanical properties of PVC in PVC‐PE melt blends: Effects of molecular architecture, content, and MFI of PE
Authors: Thongpin C. , Santavitee O. , Sombatsompop N. 
Published: July 2006

AbstractThermal degradation mechanism and mechanical properties of poly(vinyl chloride) (PVC) in PVC–polyethylene (PE) mixtures with varying types, contents, and melt flow indexes of the PE were studied. The degradation behavior was investigated in terms of decomposition temperature and glass transition temperature, polyene index, and morphology of the PVC in the mix. The results suggested that adding small amounts of PE (5 phr) in PVC‐PE mixtures could thermally stabilize the PVC, as noted by an increase in its decomposition temperature. At higher PE loading, the PVC encountered more degradation as a result of a consumption of the heat stabilizer by PE radicals and the dehydrochlorination reaction. A radical transfer reaction was proposed to explain the degradation mechanism of the PVC in the PVC‐PE melt, specifically a progressive increase of the glass transition temperature of the PVC in the mix as a result of increasing PE content. The PVC‐PE blend using HDPE with high MFI exhibited more pronounced thermal and structural changes of PVC. The mechanical properties of the PVC‐PE blend were very much dependent on the PE content, but slightly affected by the type and MFI value of the PE. The dispersion level of the PE in the PVC phase was found to play an important role in affecting the mechanical properties of the PVC‐PE mixtures. J. VINYL. ADDIT. TECHNOL. 12:115–123, 2006. © 2006 Society of Plastics Engineers
The Congenital Intrahepatic Arterioportal Fistula Syndrome
Authors: Norton Seamus P. , Jacobson Kevan , Moroz Stanley P. , Culham Gordon , Ng Vicky , Turner Justine , John Philip 
Published: July 2006

ABSTRACTCongenital intrahepatic arterioportal fistula is a rare but treatable cause of portal hypertension for which early recognition may lead to successful radiological management. We report an infant presenting with severe failure to thrive, melena and splenomegaly due to a congenital intrahepatic arterioportal fistula, successfully ablated after multiple trials of superselective transarterial embolization. Comprehensive review of congenital cases provides an understanding of the key clinical features defining this syndrome. A classification system is proposed, upon which treatment decisions may be based.
Functional Fecal Soiling Without Constipation, Organic Cause or Neuropsychiatric Disorders?
Authors: Pakarinen Mikko P. , Koivusalo Antti , Rintala Risto J. 
Published: July 2006

ABSTRACTBackground:The aetiology of fecal incontinence in children has traditionally been attributed to idiopathic constipation, structural defects or neuropsychiatric disorders. We describe a new subgroup of otherwise healthy children who have fecal soiling without any underlying cause for the incontinence.Methods:The hospital records of children with fecal incontinence were screened to detect patients without any history, signs or symptoms of constipation or an organic, neurological or psychiatric cause for the incontinence. Anorectal manometry findings were compared with those of age‐matched children with idiopathic constipation and soiling.Results:Eight boys and 5 girls were identified. The median age at diagnosis was 7.9 years. Soiling had lasted median of 4.1 years, occurred at least every other day in 9, at least once a week in 2 and occasionally in 2 and required change of underwear or use of protective pads. Abdominal x‐ray and barium enema showed normal findings. Sacral x‐ray and/or MRI of the spinal cord showed normal bony spine and spinal cord. Five children had coexisting night and/or daytime wetting. Impaired rectal sensation was the only identifiable abnormality that was detected. The median volume required for the first sensation was 45 mL (range, 15‐100 mL; normal, <15 mL). Anorectal manometry alone was unable to differentiate patients with functional fecal soiling from those with idiopathic constipation associated soiling. The median follow‐up time after the diagnosis was 9.1 months. Treatment of fecal soiling consisted of education, dietary modification or stimulatory laxatives to establish regular toileting routines. Treatment improved fecal continence in 6 out of 8 cases with follow‐up longer than 6 months.Conclusions:There is a small subgroup of children with fecal soiling who are otherwise healthy without constipation or any other underlying cause for the incontinence. These children seem to have isolated impairment of rectal sensation. In most, the prognosis is good with conservative treatment.
The Role of Pro‐Inflammatory Cytokines in Inflammatory Bowel Disease Growth Retardation
Authors: Wong S.C. , MacRae V.E. , McGrogan P. , Ahmed S.F. 
Published: July 2006

ABSTRACTChildhood inflammatory bowel disease (IBD) especially those with Crohn disease is commonly complicated by faltering growth and pubertal delay. Pro‐inflammatory cytokines are often elevated in IBD and may affect linear growth and puberty either systemically or at the level of the growth plate. Further study of the underlying mechanisms of the deleterious effects of cytokines on the growth plate may improve management of faltering growth in childhood IBD. Well‐controlled clinical studies of the respective effect of nutritional support, immunomodulatory therapy, biological agents and growth and puberty promoting agents on managing faltering growth also require further attention.
Rhamnose and Rhamnitol in Dual Sugar Permeability Tests
Authors: Malagon Ignacio , Onkenhout Willem , Klok Margreet , van der Poel Petrus F.H. , Bovill James G. , Hazekamp Mark G. 
Published: July 2006

ABSTRACTRhamnose is one of the sugars regularly used to conduct the dual sugar permeability test. For more than 30 years, it has been assumed that rhamnose is an inert sugar not metabolized by the human body and only fermented by some colonic bacteria into rhamnulose. While conducting an investigation on gut permeability in children undergoing cardiac surgery, increased concentrations of rhamnitol were found in the urine samples. The present report suggests that rhamnose is not an inert sugar and it is partially metabolized into rhamnitol by the human body.
Serum Leptin and Cytokines in Whole Blood in Relation to Clinical and Nutritional Status in Cystic Fibrosis
Authors: Schmitt‐Grohé Sabina , Hippe Valerie , Igel Michael , von Bergmann Klaus , Posselt Hans G. , Krahl Andreas , Smaczny Christina , Wagner Thomas O.F. , Nikolaizik Wilfried , Lentze Michael J. , Zielen Stefan 
Published: July 2006

ABSTRACTObjectives:Leptin plays an important role in the energy balance and may be affected by hormonal and metabolic derangement associated with chronic disease. The aim of this study was to assess the correlation between leptin, proinflammatory cytokines and nutritional status with regard to clinical status in homozygous delta F 508 cystic fibrosis patients.Methods:Patients with mild (Shwachman score 71‐100 points, group A) disease were compared with those with moderate disease (Shwachman score 41‐55 points, group B) and age‐matched controls (group C, n = 22). Leptin was assessed by enzyme‐linked immunosorbent assay and cytokines (interleukin‐8, tumor necrosis factor α) before and after stimulation with 5 ng lipopolysaccharide by a chemiluminescent immunometric assay.Results:Twenty‐two patients were recruited for each group (median A/B/C forced expiratory volume in 1 second 80%/59%/‐; median age 12/13.5/12.5 years). Leptin (median 3.25/2.65/3.3 pg/mL; P = 0.083) and body mass index were lower (group A/B/C 18.55/16.75/20.5 kg/m2; P = 0.023), but dietary intake was significantly higher (group A/B/C 50.5/68/43 kcal/kg body weight; P = 0.026) in moderate disease. Cytokines before stimulation with lipopolysaccharide were highest in moderate disease, but there was no significant difference after stimulation (interleukin‐8 median A/B/C before‐15/25.1/8.0 pg/mL, P < 0.005; after‐570.5/573.5/415.5 pg/mL, not significant; tumor necrosis factor α median A/B/C 43/56/30 pg/mL, P < 0.0001; 580/427/720.5 pg/mL, not significant.).Conclusions:There is a physiological regulation of leptin even in more advanced states of disease with significantly lower body mass index than controls. However, our data do not support the idea of elevated cytokine levels inducing anorexia in homozygous delta F 508 cystic fibrosis patients.