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Good Homogeneity (good + homogeneity)
Selected AbstractsExternal validation of a risk group defined by recursive partitioning analysis in patients with head and neck carcinoma treated with surgery and postoperative radiotherapyHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 9 2007Xavier León MD Abstract Background: Several clinical trials have proved that concurrent chemoradiotherapy is more efficacious than radiotherapy alone among high-risk patients with head and neck squamous cell carcinoma (HNSCC) who undergo surgery. A risk-group classification defined according to a recursive partitioning analysis (RPA) for these patients has been recently proposed. The objective of the present study was to carry out an external validation of this RPA-derived classification system. Methods: A retrospective study of 442 HNSCC patients treated with surgery and postoperative radiotherapy was conducted. The external validity of the RPA-derived classification system was assessed, and its ability to stage patients and to predict locoregional control of the disease was compared with the TNM system. Results: The RPA-derived classification system succeeded in obtaining a monotonic prognosis gradient in locoregional control of the disease with increasing stage, and achieved greater differences in survival between stages than the TNM and pTNM classifications. Besides, the RPA method had a better homogeneity of the categories included in each stage, and in the heterogeneity between stages. Conclusions: The RPA-derived classification system allowed for the clear definition of prognostic groups in surgically treated HNSCC patients, improving the prognostic capacity of the TNM and pTNM classifications. The RPA-derived classification system is a useful tool in the definition of patients who, given a poor prognosis, should be considered candidates to adjuvant chemoradiotherapy. © 2007 Wiley Periodicals, Inc. Head Neck, 2007 [source] Cation Ordering and Dielectric Characteristics in Barium Zinc NiobateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2007Chun-Te Lee Barium zinc niobate (Ba(Zn1/3Nb2/3)O3) (BZN) complex perovskite has been reported to have special microwave dielectric properties with close relation of its ordered structure. This study investigated the effect of calcination on the evolution of ordered structure and on quality factor with Raman spectroscopy, X-ray diffractometry, and transmission electron microscopy. The results revealed that single calcination at a lower temperature inhibited the growth of the ordered domain during sintering. In contrast, the 1:2-ordered domain in double-calcined BZN powder grew significantly with a higher sintering temperature and a longer soaking time. It is attributed that double calcination caused a higher degree of 1:2 ordering and better homogeneity. At the same time, the quality factor of the sintered ceramic body was highly promoted when using double-calcined powder. A close relation of the quality factor with the size of ordered domain, the degree of 1:2 ordering, and the relative density of BZN ceramics was presented. [source] Characteristics of polystyrene/polyethylene/clay nanocomposites prepared by ultrasound-assisted mixing processPOLYMER ENGINEERING & SCIENCE, Issue 7 2004J. G. Ryu In this study, polymer-clay nanocomposites of various concentrations were prepared by ultrasonically assisted polymerization and melt-mixing processes. A sonication process using power ultrasonic waves was employed to enhance nano-scale dispersion during melt-mixing of polymer blends and organically modified clay. We expected enhanced breakup of layered silicate bundles and further reduction in the size of the dispersed phase, with better homogeneity compared to the different immiscible blend pairs. X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) were used to characterize the structures of the nanocomposites. The rheological behaviors of the obtained nanocomposites were measured with parallel plate rheometry. It was found that the ultrasound-assisted process successfully generated exfoliated nanocomposites and promoted in-situ compatibilization of the matrix comprising an immiscible pair of polymers in a blend. The resulting nanocomposite exhibited superior thermal stability and elastic modulus compared to the base polymer. Polym. Eng. Sci. 44:1198,1204, 2004. © 2004 Society of Plastics Engineers. [source] Preparation of a Synthetic Titanite Glass Calibration Material for In Situ Microanalysis by Direct Fusion in Graphite Electrodes: A Preliminary Characterisation by EPMA and LA-ICP-MSGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2005Magne Ødegård matériaux de calibration; microanalyse; fusion directe; électrodes de graphite; verre de titanite This paper describes a technique for the preparation of a titanite (CaTiSiO5) glass calibration material for use in in situ microanalysis of major, minor, and trace elements in geological materials. The starting composition was a titanite matrix doped with minor and trace elements at , 200 ,g g -1. The elements Sc, Y, REEs, Th and U were added in the form of nitrates in solution, and the elements V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Hf and W were added as solid oxides. The synthetic titanite glass was produced by direct fusion by resistance heating in graphite electrodes at 1600-1700 °C, and quenched in air. Backscattered electron images indicate good homogeneity, with no signs of separate phases or vesicles, and analysis of the major elements Ca, Ti and Si by electron microprobe showed relative standard deviations between 0.5 and 0.7%, based on six independent measurements. Deviations from nominal concentrations for Ca, Si and Ti were measured to -1.2, -3.3 and -0.8%, respectively. The homogeneity of the trace elements in the glass was assessed by LA-ICP-MS analyses, using NIST SRM 610, 612 and 616 as external calibrators, and Ca as the internal standard element. Determinations were made both with a quadrupole mass spectrometer and a sector field instrument, and both raster and spot modes of analysis were used. For the majority of doped elements, precision was better than 10%, and relative deviations from nominal values were, with few exceptions, between 5 and 10%. Cet article décrit une technique de préparation d'un verre de composition CaTiSiO5 (titanite) pour l'utiliser comme matériau de calibration lors de microanalyses in situ des éléments majeurs, mineurs et en trace dans des matériaux géologiques. La composition de départ a une matrice de titanite, dopée avec des éléments mineurs et en trace à une concentration de , 200 ,g g-1. Les éléments Sc, Y, REE, Th et U ont été ajoutés sous forme de nitrates en solution et les éléments V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Hf et W sous forme d'oxydes solides. Le verre synthétique de titanite a été produit par fusion directe avec un chauffage par des résistances dans des électrodes de graphite à 1600-1700 °C suivi d'un refroidissement rapide à l'air. Les images obtenues par électrons rétrodiffusés montrent que le verre présente une bonne homogénéité, sans aucun signe de phases individualisées ou de vésicules, et l'analyse des éléments majeurs Ca, Ti et Si par microsonde électronique a des déviations standard relatives (RSD) entre 0.5 et 0.7% provenant de six mesures indépendantes. Les déviations par rapport aux concentrations calculées, pour Ca, Si et Ti, sont de -1.2, -3.3 et -0.8% respectivement. L'homogénéité de répartition des éléments en trace dans le verre a été vérifiée par des analyses LA-ICP-MS, en utilisant les matériaux de référence NIST SRM 610, 612 et 616 pour la calibration externe et Ca comme élément standard interne. Les déterminations ont été faites avec un spectromètre de masse de type quadrupôle et un autre de type secteur magnétique, par des analyses à la fois en mode balayage et en mode ponctuel. Pour la majorité des éléments dopés, la précision est meilleure que 10% et les déviations standard relatives par rapport aux valeurs calculées sont, à quelques exceptions près, entre 5 et 10%. [source] Preparation and Certification of High-Grade Gold Ore Reference Materials (GAu 19-22)GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2001Tiexin Gu materiau de référence certifié; gisement d 'or,GAu 19-22,IGGE,valeurs certifiées Two types of gold deposit with both good homogeneity and a high-grade of gold were selected to prepare four gold ore reference materials (GAu-19,GAu-20,GAu-21 and GAu-22) by the Institute of Geophysical and Geochemical Exploration (IGGE),China. Seven laboratories participated in the certification programme. Volumetric methods for GAu19-21 and atomic absorption spectrometry for GAu-22 were used for the homogeneity testing,the coefficient of variation being found to be less than 3%. After sample digestion and preconcentration,the samples were analysed by flame atomic absorption spectrometry (AAS),colorimetry,neutron activation analysis (NAA)and volumetric analysis. The certified values for the gold concentration in GAu19-22 are 18.3 ,g g -1, 32.3 ,g g -1, 53.0 ,g g -1 and 5.72 ,g g -1,respectively. Deux types de gisements d'or, présentant à la foisune bonne homogénéité et une teneur élevée en or, ont été sélectionnés par l'Institut d 'Exploration Géophysique et Géochimique de Chine (IGGE)afin de préparer quatre matériaux de référence pour l'or (GAu-19,GAu-20,GAu-21 et Gau-22). Sept laboratoires ont participé au programme de certification. Des méthodes volumétriques (GAu-19-21)et de spectrométrie par absorption atomique (GAu 22)ont été utilisées pour tester l'homogénéité de ces échantillons;les coefficients de variation se sont révélés inférieurs à 3%.Après la mise en solution et la préconcentration des échantillons,ceux-ci ont eté analysés par spectrométrie d 'absorption atomique (AAS), colorimétrie,activation neutronique (NAA)et analyse volumétrique.Les valeurs certifiées pour la concentration en or de GAu19-22 sont respectivement de 18.3 ,g.g -1,32.3 ,g g -1, 53.0 ,g g -1 et 5.72 ,g g -1. [source] Long-Range-Ordered, Molecular-Induced Nanofaceting,ADVANCED MATERIALS, Issue 21 2006M. Fanetti Ordered molecular nanostructured films (see figure) are obtained by exploiting the molecular-induced substrate faceting transition, following a very simple protocol. The obtained nanostructures show univocal alignment and quite good homogeneity, and the pattern periodicity can be controlled in the process. The stepped structure of the vicinal metallic substrate has a key role in the film production mechanism. [source] Preparation and properties of polyhedral oligosilsequioxane tethered aromatic polyamide nanocomposites through Michael addition between maleimide-containing polyamides and an amino-functionalized polyhedral oligosilsequioxaneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2006Ying-Ling Liu Abstract Polyhedral oligosilsequioxane (POSS) tethered aromatic polyamide nanocomposites with various POSS fractions were prepared through Michael addition between maleimide-containing polyamides and amino-functionalized POSS. The chemical structures of the polyamide,POSS nanocomposites were characterized with Fourier transform infrared and 1H NMR. The polyamide,POSS nanocomposites exhibited good homogeneity in scanning electron microscopy and transmission electron microscopy observations. POSS modification increased the storage modulus and Young's modulus of the polyamides, slightly decreased their glass-transition temperatures from 312 to 305 °C, and significantly lowered their dielectric constants from 4.45 to 3.35. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4632,4643, 2006 [source] Preparation and properties of high performance epoxy,silsesquioxane hybrid resins prepared using a maleimide,alkoxysilane compound as a modifierJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2005Ying-Ling Liu Abstract An alkoxysilane compound possessing maleimide moiety (MSM) was prepared from N-(4-hydroxyphenyl)maleimide and 3-glycidoxypropyltrimethoxysilane and was used as a modifier of epoxy resins. In situ curing epoxy resins with MSM resulted in epoxy resins with good homogeneity. Just 5,10 wt % of MSM is sufficient to yield high glass transition temperature (165 °C), good thermal stability above 360 °C, and high flame retardancy (LOI = 30) to bisphenol-A-based epoxy resins. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5787,5798, 2005 [source] Effect of High-Energy Vibromilling on Interfacial Interaction and Mechanical Properties of PVC/Nano-CaCO3 CompositesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 9 2005Manhong Tian Abstract Summary: The effects of interfacial interaction between nano-CaCO3 and PVC on mechanical properties and morphology of PVC/nano-CaCO3 composites were studied. Nano-CaCO3 was treated with vibromilling in the presence of PVC and coupling agents. The mechanical properties of PVC/treated nano-CaCO3 are remarkably improved. Transmission electron microscopy results revealed that vibromilled nano-CaCO3 particles are well dispersed in PVC matrix with good homogeneity and well adhered to PVC matrix. Molau test indicated that chemical reaction between newly formed surface of nano-CaCO3 and PVC or coupling agent took place. Theoretical calculation results show that the interfacial interaction between PVC and nano-CaCO3 are substantially improved through vibromilling treatment of nano-CaCO3 in the presence of PVC and coupling agent. Molau test results of the samples in THF. [source] Anisotropic FMR-linewidth of triple-domain Fe layers on hexagonal GaN(0001)PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006M. Buchmeier Abstract We present a ferromagnetic resonance (FMR) study of Fe films with thicknesses between 5 and 70 nm prepared by electron-beam evaporation on top of hexagonal GaN(0001). X-ray diffraction (XRD) and low-energy electron diffraction (LEED) suggest the growth in crystallographic Fe(110) domains with three different orientations. The magnetic properties have been investigated by in-plane angle-dependent FMR at frequencies between 4.5 to 24 GHz. All samples show a hexagonal in-plane anisotropy with the easy axes oriented parallel to the Fe [001] directions. The anisotropy field strength of about 8 mT reveals a bulk-like thickness dependence. Therefore, we can exclude the following origins of anisotropy: (i) interface effects because of the bulk-like thickness dependence and (ii) averaged first order cubic or uniaxial anisotropies arising from the three grain orientations because of the relative strengths. We qualitatively explain the sixfold anisotropy by spin relaxation inside the grains. The FMR linewidth versus frequency curves are linear with almost no zero-frequency offset indicating a good homogeneity of the magnetic properties over the sample area. However, the effective damping parameter , shows pronounced anisotropy and thickness dependence, with enhanced damping along the hard axes and for thicker layers. We suggest that the additional damping can be explained by two-magnon scattering at defects which are due to the triple domain structure. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] In-situ IR synchrotron mapping ellipsometry on stimuli-responsive PAA-b-PS/PEG mixed polymer brushesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010Dennis Aulich Abstract A binary polymer brush consisting of weak polyelectrolytes was investigated with infrared synchrotron mapping ellipsometry in-situ under the influence of different aqueous solutions. Thickness of the brush layer in dry state was ,15 nm. The brush, consisting of poly(ethylene glycol) and poly(acrylic acid)-b-poly(styrene) in a 50/50 composition was switched between two different states by changing the pH of the solution. An IR mapping ellipsometer at the IRIS beamline located at the BESSY II synchrotron facility in Berlin, Germany, was used for high lateral resolution in-situ measurements. The results show strong chemical changes in the brush layer due to COOH , COO, conversion of the PAA's carboxylic groups. Measurements with spot sizes of ,1 mm on different positions on the samples proved good homogeneity of the brush layer and the qualification of this method for investigation of ultrathin organic films in aqueous solutions in-situ with IR ellipsometry. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||