bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the adsorption of surfactants on the poly(styrene) latex particles by small‐angle X‐ray scattering
Authors: Seelenmeyer S. , Ballauff M. 
Published: March 2011

AbstractWe present the study of the adsorption of a non‐ionic surfactant onto latex particles by small‐angle X‐ray scattering (SAXS). The analysis of the process of adsorption by SAXS is discussed in detail. It is demonstrated that SAXS allows to monitor the gradual built‐up of the surface layer with increasing amount of added surfactant. SAXS also allows to obtain the radial volume fraction of the hydrophilic tails of the surfactant. Possible limitations of this analysis are discussed.
Investigation of swelling and diffusion in polymers by NMR imaging
Authors: Knörgen Manfred , Heuert Uwe , Schneider Horst , Kuckling Dirk , Richter Sven , Arndt Karl‐Friedrich 
Published: March 2011

AbstractThe kinetics of diffusion in polymers ranges from simple Fickian diffusion to higher order diffusion, such as Case II diffusion1‐2). The conventional method for determining the characteristics of solvents into polymer matrices is by measuring the mass uptake of the polymer as the solvent penetrates the matrix. However, since such measurements perform observations at a macroscopic level, little information has been obtained relating to the nature of the solvent in the polymer matrix and the mechanisms of the processes that control the diffusion. Nuclear magnetic resonance (NMR) imaging (‘MRI’) has been used to observe the penetration of solvents into solid systems in realtime. The method provides a one‐ or more‐dimensional image of the density and the mobility of the solvent in a material or of the network changes of the material itself due to the softening influence of the solvent. The first (imaging of the solvent) can be used for a quantitative measurement of the diffusion whereas the observation of the network gives information about the changing of the network (mobility, de‐crystallization…) during the swelling process. For example the diffusion of organic solvents in some polymeric materials (natural rubber, water gels (PNIPAAm), and nematic diblock‐copolymers) are investigated.
Neutral and charged polymer brushes at solid surfaces
Authors: Biesalski Markus , Johannsmann Diethelm , Rühe Jürge N. 
Published: March 2011

AbstractNeutral and charged polymer brushes covalently attached to planar solid surfaces were generated by using self‐assembled monolayers of an azo initiator and radical chain polymerization in situ. The brushes were characterized by FTIR‐spectroscopy, optical waveguide‐spectroscopy and Ellipsometry. Especially the film thicknesses of surface bound polyelectrolyte (PEL) monolayers were measured by optical waveguide spectroscopy (OWS) as a function of the humidity of the environment. The PEL brushes show strong increases in thickness as well as strong decrease of the refractive index of the surface attached layer due to water incorporation caused by the exposure to the humid environment. Additionally the behavior of neutral as well as charged brushes in contact with solvent was investigated by using multiple‐angular‐scans of ellipsometry in a total internal reflectance setup. The scaling behavior of the brush height as a function of the graft density of the attached polymer molecules was investigated for the neutral brush as well as for the PEL brush system.
NMR and vibrational spectroscopic study of the order and mobility in polycarbonate and polycarbonate — poly(ethylene oxide) blends
Authors: Dybal Jiří , Brus Jiří , Schmidt Pavel 
Published: March 2011

AbstractTime dependence of the gel formation in toluene solutions of polycarbonate (PC) was investigated by two‐dimensional Fourier‐transform infrared (2D FT‐IR) correlation spectroscopy. The 2D correlation approach reveals that there are at least three bands in the C=O stretching region. The intensity increase of the band at 1771 cm−1 occurs later compared with the onset of the intensity changes of the bands at 1778 and 1765 cm−1 corresponding to amorphous and crystalline‐like domains, respectively. The band at 1771 cm−1 is assigned to the chain conformations occurring in the partial‐order regions accompanying crystalline‐like domains. Splitting of the signals of aromatic carbons in the solid‐state 13C CP/MAS NMR spectra of semicrystalline PC and PC‐PEO blends indicates restricted mobility resulting from the fixed ordering due to partial crystallinity of PC itself and from blending of PC with PEO. The decreasing mobility of PC with the increasing content of highly mobile PEO in the blends was proved by the dipolar dephasing rates obtained in the 1H‐1H CRAMPS (combined rotation and multi‐pulse spectroscopy) NMR experiments.
Comparative analysis of structure and temperature behaviour of two copolyamides ‐ regular KEVLAR and statistical ARMOS
Authors: Levchenko Andrei A. , Antipov Evgueni M. , Plate' Nikolaj A. , Stamm Manfred 
Published: March 2011

AbstractIn the present investigation X‐ray diffraction techniques, DSC and dynamic mechanical relaxation (DMR) methods have been employed to compare the structure and thermal behaviour of Kevlar (“DuPont”, USA) and Armos (Russia) fibers. Our recent studies have indicated that the non‐crystalline phase of copolyesters always contains LC smectic structure in addition to some part of the nematic LC mesophase. It turned out that the copolyamides also possess this interesting feature. Moreover, on heating of a semicrystalline copolyester always the second order phase transition from the crystalline state to condis mesophase has been observed, whereas in the case of copolyamides such a transition has the «virtual» character. As was established by other authors both polymers under study reveal the moisture content. The changes in wide angle X‐ray scattering of copolyamides under heat treatment were interpreted in terms of desorption of bound water and structural rearrangement in the plane perpendicular to the chain axis involving of the hydrogen bonding between neighboring macromolecules.
Mechanical behavior of polymer microlayers
Authors: Kerns Julia , Hsieh Alex , Hiltner Anne , Baer Eric 
Published: March 2011

AbstractThe mechanical behavior of polycarbonate (PC) coextruded as microlayers with a brittle polymer, either poly(styrene‐co‐acrylonitrile) (SAN) or poly(methyl methacrylate) (PMMA), was examined. Adhesion between layers was measured with the T‐peel method. The much higher interfacial toughness of PC/PMMA microlayers compared to PC/SAN was attributed to partial miscibility. Comparison of the microdeformation behavior of 32‐layer PC/SAN and PC/PMMA microlayers revealed that very good adhesion between PC and PMMA constrained yielding of the PC. This was seen in the tensile stress‐strain curves as a broader stress drop at the yield point and a lower fracture strain. Decreasing the layer thickness by increasing the number of layers enhanced the ductility of both PC/SAN and PC/PMMA microlayers. A PC/PMMA microlayer with 4096 layers and a composition of 80% PC achieved the ballistic performance of polycarbonate.
Study of the structural changes in urea‐formaldehyde condensates during synthesis
Authors: Siimer Kadri , Pehk Tõnis , Christjanson Peep 
Published: March 2011

AbstractChemical constitution of urea‐formaldehyde resins in synthesis and in storage was determined using 13C NMR spectroscopy. Methylolation, methylene and dimethylene ether bond‐forming reactions were discussed. The changes in the content of structural elements with secondary and tertiary amino groups of urea at various stages were followed. The resin synthesis technology was used, which considers the requirement in low free formaldehyde content, connected with somewhat smaller storage stability of resins.
The effect of prepolymer composition of amino‐hardened liquid crystalline epoxy resins on physical properties of cured thermoset
Authors: Carfagna Cosimo , Amendola Eugenio , Giamberini Marta , D'Amore Alberto , Priola Aldo , Malucelli Giulio 
Published: March 2011

AbstractDiglycidyl terminated 4,4'‐oxydiphenyl cured with an aromatic diamine exhibits liquid crystalline properties, even if the amount of hardener is used in defect with respect to the stoichiometric amount. Physical properties of the resin, hardened with different quantities of amine are presented and discussed. In particular the high values of fracture toughness of this class of thermoset has been explained on the basis of the biphasic nature of the crosslinked resin. The differences in mechanical properties are analyzed taking into account the different crosslink densities.
Characterization of poly(methylphenylsilane) prepared by plasma polymerization
Authors: Cech Vladimir , Horvath Pavel , Jancar Josef , Schauer Frantisek , Nespurek Stanislav 
Published: March 2011

AbstractPoly(methylphenylsilane) plasma polymer layers of the thickness ranging from 10−2 to 100 μm intended to engineer interphases in glass fibre reinforced polymer composites and light‐emitting displays were prepared by r.f. glow discharge technique. The films synthesized from a mixture of dichloro(methyl)phenylsilane vapor and gaseous hydrogen were deposited on flat glass and silicon substrates and glass fibres as well. Deposition conditions were optimized to obtain required thickness, mechanical and electrical properties of interphases. Prepared layers were amorphous, relatively rigid and transparent at room temperature with excellent adhesion to substrates. The surface of plasma polymer is rough with isolated (silicon substrate) and conglomerate (glass substrate) grains. FTIR and XPS spectra revealed a great amount of atomic oxygen bound to silicon atoms and enabled to determine the atomic concentrations. The structure model is proposed assuming a carbosiloxane network with not‐crosslinked methyl and phenyl groups.
Processing, properties and morphology of polypropylene‐epdm blends
Authors: López‐Manchado Miguel A. , Biagiotti Jerico , Arroyo Miguel , Kenny José M. 
Published: March 2011

AbstractBlends of polypropylene and an elastomer (ethylene propylene diene terpolymer, EPDM) are systematically investigated to determine the effect of the rubber on the polymer properties. Five compositions on the complete range of blend compositions are analyzed. The study reported here is a first of a series which main objective is to analyze in a systematic way the influence of the different factors that determine the effectiveness of EPDM as an impact modifier for PP. In this first part of the study, the processing behavior of the PP‐EPDM blends are analyzed and the mechanical properties of the processed blends (tensile, flexural and impact resistance) are examined. Halpin‐Tsai and porosity models successfully represent the mechanical behavior of the blends. The model results allow a physical interpretation of the role of the dispersed phase in terms of the aspect ratio and of the stress concentration factors associated to the dispersed particles. Moreover, the mechanical properties are correlated with the morphology of the blends studied by scanning electron microscopy, where two phases are clearly observed in the complete range of compositions. The results show that PP‐EPDM blends with at low rubber content present a good processability, without significant deterioration with respect to neat PP and with a considerable improvement of the room and low temperature performance.
Qualitative and quantitative skeletal muscle ultrasound in late‐onset acid maltase deficiency
Authors: Zaidman Craig M. , Malkus Elizabeth C. , Siener Catherine , Florence Julaine , Pestronk Alan , Al‐Lozi Muhammad 
Published: March 2011

AbstractIntroduction: Acid maltase deficiency (AMD, or Pompe disease) is an inherited myopathic disorder of glycogen degradation. Diagnosis is often delayed. Muscle ultrasound could improve diagnosis. Methods: We compared skeletal muscle ultrasound images from adults with AMD (n = 10) to other myopathies (n = 81) and, in AMD, compared qualitative (Heckmatt) and quantitative (backscatter) ultrasound measurements with strength and function. Results: Qualitative ultrasound was abnormal in at least one muscle in all AMD subjects. Ultrasound patterns specific for AMD were: normal triceps brachii despite abnormalities in elbow flexors (89% vs. 17%, P < 0.0001); focal abnormalities affecting deep more than superficial biceps brachii (40% vs. 4%, P = 0.002); and more severe involvement of vastus intermedius than rectus femoris (40 vs. 11%, P = 0.03). In AMD, both qualitative (Heckmatt) and quantitative (backscatter) ultrasound measures increased with decreasing strength and function. Conclusions: Muscle ultrasound identifies the presence and specific patterns of AMD pathology, measures disease severity, and can help in the diagnosis of AMD. Muscle Nerve 44: 418–423, 2011
Genomic evidence of pre‐invasive clonal expansion, dispersal and progression in bronchial dysplasia
Authors: McCaughan Frank , Pipinikas Christodoulos P , Janes Sam M , George P Jeremy , Rabbitts Pamela H , Dear Paul H 
Published: March 2011

AbstractThe term ‘field cancerization’ is used to describe an epithelial surface that has a propensity to develop cancerous lesions, and in the case of the aerodigestive tract this is often as a result of chronic exposure to carcinogens in cigarette smoke 1, 2. The clinical endpoint is the development of multiple tumours, either simultaneously or sequentially in the same epithelial surface. The mechanisms underlying this process remain unclear; one possible explanation is that the epithelium is colonized by a clonal population of cells that are at increased risk of progression to cancer. We now address this possibility in a short case series, using individual genomic events as molecular biomarkers of clonality. In squamous lung cancer the most common genomic aberration is 3q amplification. We use a digital PCR technique to assess the clonal relationships between multiple biopsies in a longitudinal bronchoscopic study, using amplicon boundaries as markers of clonality. We demonstrate that clonality can readily be defined by these analyses and confirm that field cancerization occurs at a pre‐invasive stage and that pre‐invasive lesions and subsequent cancers are clonally related. We show that while the amplicon boundaries can be shared between different biopsies, the degree of 3q amplification and the internal structure of the 3q amplicon varies from lesion to lesion. Finally, in this small cohort, the degree of 3q amplification corresponds to clinical progression. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Increased production of sonic hedgehog by ballooned hepatocytes
Authors: Rangwala Fatima , Guy Cynthia D , Lu Jiuyi , Suzuki Ayako , Burchette James L , Abdelmalek Manal F , Chen Wei , Diehl Anna Mae 
Published: March 2011

AbstractBallooned hepatocytes distinguish non‐alcoholic steatohepatitis (NASH) from steatosis. Such cells contain dilated endoplasmic reticulum and ubiquitin aggregates, characteristics of endoplasmic reticulum stress. Hepatocyte ballooning increases the risk for fibrosis in NASH, suggesting that ballooned hepatocytes release pro‐fibrogenic factors. Hedgehog ligands function as pro‐fibrogenic factors in liver diseases, but mechanisms for hedgehog ligand production remain poorly understood. We evaluated the hypothesis that endoplasmic reticulum stress induces hepatocyte production of hedgehog ligands that provide paracrine pro‐fibrogenic signals to neighbouring cells. In livers from NASH patients, keratin 8/18 and ubiquitin staining demonstrated enlarged, keratin 8/18‐negative/ubiquitin‐positive hepatocytes (ballooned hepatocytes) that were positive for Sonic hedgehog. In order to model endoplasmic reticulum stress in vitro, primary mouse hepatocytes were treated with tunicamycin. Compared to vehicle, tunicamycin significantly increased Sonic hedgehog and Indian hedgehog expression. Furthermore, conditioned medium from tunicamycin‐treated hepatocytes increased Gli‐luciferase reporter activity 14‐fold more than conditioned medium from vehicle‐treated hepatocytes. Cyclopamine (hedgehog signalling inhibitor) abrogated the effect of conditioned medium from tunicamycin‐treated hepatocytes, verifying that soluble hepatocyte‐derived factors activate hedgehog signalling. Ballooned hepatocytes in NASH patients did not express the hedgehog target gene, Gli2, α‐smooth muscle actin or vimentin, but were surrounded by Gli2‐positive stromal cells expressing these myofibroblast markers. Trichrome staining demonstrated the accumulation of ballooned hepatocytes in areas of matrix deposition, and numbers of Sonic hedgehog‐positive hepatocytes correlated with the degree of ballooning and fibrosis stage. Hepatocytes undergoing endoplasmic reticiulum stress generate hedgehog ligands which act as paracrine pro‐fibrogenic factors for hedgehog‐responsive stromal cells. These results help to explain why fibrosis stage correlates with hepatocyte ballooning in NASH. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Usefulness of the hematopoietic cell transplantation‐specific comorbidity index (HCT‐CI) in predicting outcomes for adolescents and young adults with hematologic malignancies undergoing allogeneic stem cell transplant
Authors: Wood William , Deal Allison , Whitley Julia , Sharf Andrew , Serody Jonathan , Gabriel Donald , Shea Thomas 
Published: March 2011

AbstractBackgroundThe HCT‐CI helps to predict non‐relapse mortality (NRM) and overall survival (OS) in allogeneic hematopoietic cell transplantation (HCT) recipients. The usefulness of this index in a younger, adolescent and young adult (AYA) population is unclear.ProcedureWe tested the validity of the HCT‐CI as a predictor of mortality in a retrospective cohort of 56 AYA recipients between the ages of 16 and 39, using chart abstraction followed by univariable and multivariate analysis.ResultsOnly pulmonary dysfunction (46%), hepatic dysfunction (27%), infection (20%), and psychiatric disturbance (11%) had frequencies greater than 5% in this population. HCT‐CI scores of 0–2 were present in 54%, and scores of >3 in 46%. The cumulative incidence of NRM at 2 years was 32%, with an OS of 46%; the NRM and OS for patients with an HCT‐CI of 0–2 were 24% and 62%, whereas the NRM and OS for patients with an HCT‐CI >3 were 38% and 28%. Patients with pulmonary dysfunction prior to transplant had a 29% OS at 2 years, compared to a 61% OS among patients without (P = 0.001). There was no statistically significant difference for patients and a worse NRM (P = 0.08). In multivariable analysis, both an HCT‐CI score of >3 and any pulmonary dysfunction remained associated with OS (P = 0.01, P = 0.03), but neither with NRM.ConclusionsThe HCT‐CI appears useful in predicting OS in AYAs, though higher scores may reflect prior treatment, with pulmonary dysfunction particularly prevalent. Prospective studies to further validate and explain these findings are warranted. Pediatr Blood Cancer 2011; 57: 499–505. © 2011 Wiley‐Liss, Inc.
Properties of microinjection molding of polymer multiwalled carbon nanotube conducting composites
Authors: Abbasi Samaneh , Derdouri Abdessalem , Carreau Pierre J. 
Published: March 2011

AbstractThe effects of processing conditions on the microstructure and properties of polypropylene/multiwalled carbon nanotube (PP/MWCNT) and polycarbonate/multiwalled carbon nanotube (PC/MWCNT) composites were studied. Samples of various MWCNT loadings were prepared by diluting commercial masterbatches. Different processing conditions were then used to systematically change the degree of nanotube alignment, from random to highly aligned. The crystallinity of the PP/MWCNT nanocomposites was found to go through a maximum as a function of nanotube content while the overall rate of crystallization increased. For the highly sheared microinjected PP/MWCNT samples well oriented crystals were formed. Electrical conductivity of the nanocomposites was improved by the presence of the crystalline structure; however, the high degree of nanotube alignment in the microparts resulted in a significant increase in the electrical percolation threshold. The PP nanocomposites exhibited mechanical properties significantly enhanced by nanotube loading; this effect was small in the case of the PC nanocomposites. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
On the measurement of fracture toughness of soft biogel
Authors: Kwon H.J. , Rogalsky Allan D. , Kim Dong‐Woo 
Published: March 2011

AbstractIn this study, the rate dependent energy dissipation process and the fracture toughness of physical gels were investigated using agarose as a sample material. Both the J‐integral and Essential work of Fracture (EWF) methods were examined. To assess the quasi‐static fracture toughness of gels, linear regression was performed on critical J (Jc) values at different loading rates resulting in a quasi‐static Jc value of 6.5 J/m2. This is close to the quasi‐static EWF value of 5.3 J/m2 obtained by performing EWF tests at a quasi‐static loading rate (crosshead speed of less than 2 mm/min). Nearly constant crack propagation rates at low loading rates, regardless of crack length, suggest viscoplastic chain pull‐out is the fracture mechanism. At high loading rates failure was highly brittle, which is attributed to sufficient elastic energy accumulation to precipitate failure by chain scission. We conclude that in physical gels quasi‐static fracture toughness can be evaluated by both the J‐integral and EWF methods provided the effects of loading rate are investigated and accounted for. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Crystallization studies on a clay nanocomposite prepared from a degradable poly(ester amide) constituted by glycolic acid and 6‐aminohexanoic acid
Authors: Morales‐Gámez Laura , Franco Lourdes , Casas María Teresa , Puiggalí Jordi 
Published: March 2011

AbstractAn intercalated nanocomposite was prepared from an organomodified clay (Cloisite 25A) and a new biodegradable poly(ester amide) characterized by an alternating arrangement of glycolic acid and 6‐aminohexanoic acid units by the melt‐mixing technique. The influence of the final silicate layer morphology on hot and cold crystallization behavior was investigated by optical microscopy, differential scanning calorimetry, and synchrotron radiation. Primary nucleation increased significantly with the incorporation of nanoparticles, in contrast with the decrease previously observed when exfoliated structures were obtained. The secondary nucleation constant was higher for the nanocomposite sample, indicating that the growth mechanism was hampered by the presence of clay particles. However, the increase in primary nucleation had a greater effect, resulting in a faster overall crystallization rate for the nanocomposite. The addition of clay particles slightly reduced the degree of crystallinity attained after the hot and cold crystallization processes and favored a lamellar insertion mechanism. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers