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Amorphous Structure (amorphous + structure)
Selected AbstractsPoly(methylmethacrylate) and Topas capillary electrophoresis microchip performance with electrochemical detectionELECTROPHORESIS, Issue 16 2005Mario Castaño-Álvarez Abstract A capillary electrophoresis (CE) microchip made of a new and promising polymeric material: Topas (thermoplastic olefin polymer of amorphous structure), a cyclic olefin copolymer with high chemical resistance, has been tested for the first time with analytical purposes, employing an electrochemical detection. A simple end-channel platinum amperometric detector has been designed, checked, and optimized in a poly-(methylmethacrylate) (PMMA) CE microchip. The end-channel design is based on a platinum wire manually aligned at the exit of the separation channel. This is a simple and durable detection in which the working electrode is not pretreated. H2O2 was employed as model analyte to study the performance of the PMMA microchip and the detector. Factors influencing migration and detection processes were examined and optimized. Separation of H2O2 and L -ascorbic acid (AsA) was developed in order to evaluate the efficiency of microchips using different buffer systems. This detection has been checked for the first time with a microchip made of Topas, obtaining a good linear relationship for mixtures of H2O2 and AsA in different buffers. [source] Characterizations of Magnetron Sputtered CrSiN/ZrN Multilayer Coatings,from Structure to Tribological Behaviors,ADVANCED ENGINEERING MATERIALS, Issue 8 2009Zhiguo Zhang In this study, CrSiN/ZrN multilayer coatings were prepared by a reactive magnetron sputtering system. The evolution of their microstructure, mechanical, and tribological properties as a function of the multilayer modulation period was studied. The results showed that the multilayers had a good modulation structure. CrSiN and ZrN individual layer in the multilayers were "amorphous-like" and amorphous structure, respectively. [source] Flexible models with evolving structureINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 4 2004Plamen P. Angelov A type of flexible model in the form of a neural network (NN) with evolving structure is discussed in this study. We refer to models with amorphous structure as flexible models. There is a close link between different types of flexible models: fuzzy models, fuzzy NN, and general regression models. All of them are proven universal approximators and some of them [Takagi-Sugeno fuzzy model with singleton outputs and radial-basis function] are interchangeable. The evolving NN (eNN) considered here makes use of the recently introduced on-line approach to identification of Takagi-Sugeno fuzzy models with evolving structure (eTS). Both TS and eNN differ from the other model schemes by their gradually evolving structure as opposed to the fixed structure models, in which only parameters are subject to optimization or adaptation. The learning algorithm is incremental and combines unsupervised on-line recursive clustering and supervised recursive on-line output parameter estimation. eNN has potential in modeling, control (if combined with the indirect learning mechanism), fault detection and diagnostics etc. Its computational efficiency is based on the noniterative and recursive procedure, which combines the Kalman filter with proper initializations and on-line unsupervised clustering. The eNN has been tested with data from a real air-conditioning installation. Applications to real-time adaptive nonlinear control, fault detection and diagnostics, performance analysis, time-series forecasting, knowledge extraction and accumulation, are possible directions of their use in future research. © 2004 Wiley Periodicals, Inc. [source] Microstructure of ball milled and compacted Co,Ni,Al alloys from the , rangeJOURNAL OF MICROSCOPY, Issue 2 2009W. MAZIARZ Summary Two powder alloys from the , phase region of compositions Co28.5Ni36.5Al35 and Co35Ni30Al35 were ball milled for 80 h in a high energy ball mill. The formation of amorphous structure was observed after 40 h of milling and further milling did not change their structure. The analytical and high-resolution transmission electron microscopy (TEM, HREM) examination of powder structure showed that nanoparticles of L10 phase of size of about 5 nm were present within the amorphous matrix. The vacuum hot pressing of the milled powders under pressure of 400 MPa at 700°C for 12 min resulted in the formation of compacts with density of about 70% of the theoretical one. The additional heat treatment at 1300°C for 6 h followed by water quenching, led to significant improvement of density and induced the martensitic transformation manifested by a broad heat effect. The characteristic temperatures of the transformation were determined using DSC measurements, which revealed only small differences within the examined alloys compositions. TEM structure studies of heat-treated alloys allowed to identify the structure of an ordered , (B2) phase and L10 martrensite. [source] Field-effect transistors based on PPV derivatives as a semiconducting layerJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2009Woo-Hyung Lee Abstract A series of modified thiophene groups containing PPV-based semiconducting materials, poly[(2,5-bis(octyloxy)-1,4-phenylenevinylene)-alt-(2,2,bithienylenevinylene)] (PPBT), poly[(2,5-bis(octyloxy)-1,4-phenylenevinylene)-alt-(5,5-thiostilylenevinylene)] (PPTVT), have been synthesized through a Horner coupling reaction. From the FTIR and 1H NMR spectroscopy, the configuration of the vinylene groups in the polymers was all trans (E) geometry. The weight-average molecular weights (Mw) of PPBT and PPTVT were found to be 11,700 and 11,800, with polydispersity indices of 2.51 and 2.53, respectively. PPBT and PPTVT thin films exhibit UV,visible absorption maxima at 538 and 558 nm, respectively, and the strong absorption shoulder peaks at 578 and 602 nm, respectively. Solution processed field-effect transistors (FET) fabricated using all the polymers showed p -type OTFT characteristics. The field-effect mobility of the PPTVT was obtained up to 2.3 × 10,3 cm2 V,1 s,1, an on/off ratio of 1.0 × 105 with ambient air stability. Studies of the atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis of the polymer thin films revealed that all the polymers were amorphous structure. The greater planarity and rigidity of PPTVT compared to PPBT results in elongation of conjugation length and better ,,, stacking of polymer chains in amorphous region, which leads to improved FET performance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 111,120, 2009 [source] Low-Temperature Atomic Layer-Deposited TiO2 Films with Low PhotoactivityJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2009Xinhua Liang Atomic layer deposition (ALD) has been successfully utilized for the conformal and uniform deposition of ultrathin titanium dioxide (TiO2) films on high-density polyethylene (HDPE) particles. The deposition was carried out by alternating reactions of titanium tetraisopropoxide and H2O2 (50 wt% in H2O) at 77°C in a fluidized bed reactor. X-ray photoelectron spectroscopy confirmed the deposition of TiO2 and scanning transmission electron microscopy showed the conformal TiO2 films deposited on polymer particle surfaces. The TiO2 ALD process yielded a growth rate of 0.15 nm/cycle at 77°C. The results of inductively coupled plasma atomic emission spectroscopy suggested that there was a nucleation period, which showed the reaction mechanism of TiO2 ALD on HDPE particles without chemical functional groups. TiO2 ALD films deposited at such a low temperature had an amorphous structure and showed a much weaker photoactivity intensity than common pigment-grade anatase TiO2 particles. [source] Characterization for water vapour barrier and heat sealability properties of heat-treated paperboard/polylactide structurePACKAGING TECHNOLOGY AND SCIENCE, Issue 8 2009Kimmo Lahtinen Abstract The moisture barrier and heat sealability properties of polylactide (PLA) extrusion-coated paperboard were investigated. The first part of the study focused on the influences of coating weight and surroundings temperature and relative humidity on the water vapour transmission rate (WVTR) of the structure. The outcome arising from this part was a simple and practical equation that allows calculating the WVTR as a function of PLA coating weight under specific thermo-hygrometric conditions. The second part of the study investigated the effect of heat treatments between 100 and 150°C on the WVTR and heat sealability of a 20,g/m2 PLA-coated paperboard. According to the results, the lowest WVTR values achieved were about 2.5 times lower than the WVTR of the untreated structure. Presumably, the PLA coating experienced two types of reordering mechanisms: crystalline growth and packing of the amorphous structure. The greatest barrier improvement was achieved when both of these mechanisms were accumulated effectively. This was observed from the samples after a 40,min treatment at 130°C. Ultimately, the crystalline growth was experienced by PLA at 100,130°C temperatures. The packing of the amorphous section, which was also accumulated at higher temperatures, was suggested to be the decisive factor influencing WVTR. According to the heat sealing results, the heat treatments causing crystalline growth resulted in considerably increased sealing temperatures and reduced applicability of the material in high-speed packaging applications. The treatments at 140,150°C caused only a slight increase in the sealing temperature and maintained the sealing performance of PLA. Copyright © 2009 John Wiley & Sons, Ltd. [source] The conversion of an organometallic compound into an intercalated thin-layer amorphous structureAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2009M. R. Othman Abstract A thin alumina-hydrotalcite (Al-HT) film was fabricated from the synthesized boehmite and HT sol samples. The sols were a Newtonian fluid within 12 h of the sol synthesis and pseudo-plastic flow thereon. Co-precipitated HT demonstrated poorly crystallized periclase and spinel structures and apparent doublet peak of hydrotalcite at 2, = 39,44°, indicative of a disordered structure. The heated Al-HT sample demonstrated highly amorphous structure with single hydrotalcite peak but barely observed ,-alumina and ,-boehmite phases. The exfoliation of the spinel, gibbsite and periclase in the Al-HT was caused by the intercalation of boehmite into the HT layers that impeded the formation of the oxides phases. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis, characterization, and acoustic properties of new soluble polyurethanes based on 2,2,-[1,4-phenylenebis(nitrilomethylylidene)diphenol and 2,2,-[4,4,-methylene-di-2-methylphenylene-1,1,-bis(nitrilomethylylidene)]diphenol,JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007A. V. Raghu Abstract Eight novel polyurethanes based on 2,2,-[1,4-phenylenebis(nitrilomethylylidene)]diphenol and 2,2,-[4,4,-methylene-di-2-methylphenylene-1,1,-bis(nitrilomethylylidene)]diphenol acting as hard segments with two aromatic and two aliphatic diisocyanates (4,4,-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) were prepared and characterized with Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, 1H-NMR and 13C-NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis. All the polyurethanes contained domains of semicrystalline and amorphous structures, as indicated by X-ray diffraction. The acoustic properties and solubility parameters were calculated with the group contribution method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Synthesis and properties of phenothiazylene vinylene-based polymers: New organic semiconductors for field-effect transistors and solar cellsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2010Seon-Kyoung Son Abstract A series of new phenothiazylene vinylene-based semiconducting polymers, poly[3,7-(4,-dodecyloxyphenyl)phenothiazylene vinylene] (P1), poly[3,7-(4,-dodecyloxyphenyl)phenothiazylene vinylene- alt -1,4-phenylene vinylene] (P2), and poly[3,7-(4,-dodecyloxyphenyl)phenothiazylene vinylene- alt -2,5-thienylene vinylene] (P3), have been synthesized via a Horner-Emmons reaction. FTIR and 1H NMR spectroscopies confirmed that the configurations of the vinylene groups in the polymers were all - trans (E). The weight-averaged molecular weights (Mw) of P1, P2, and P3 were found to be 27,000, 22,000, and 29,000, with polydispersity indices of 1.91, 2.05, and 2.25, respectively. The thermograms for P1, P2, and P3 each contained only a broad glass transition, at 129, 167, and 155 °C, respectively, without the observation of melting features. UV,visible absorption spectra of the polymers showed two strong absorption bands in the ranges 315,370 nm and 450,500 nm, which arose from absorptions of the phenothiazine segments and the conjugated main chains. Solution-processed field-effect transistors fabricated from these polymers showed p -type organic thin-film transistor characteristics. The field-effect mobilities of P1, P2, and P3 were measured to be 1.0 × 10,4, 3.6 × 10,5, and 1.0 × 10,3 cm2 V,1 s,1, respectively, and the on/off ratios were in the order of 102 for P1 and P2, and 103 for P3. Atomic force microscopy and X-ray diffraction analysis of thin films of the polymers show that they have amorphous structures. A photovoltaic device in which a P3/PC71BM (1/5) blend film was used as the active layer exhibited an open-circuit voltage (VOC) of 0.42 V, a short circuit current (JSC) of 5.17 mA cm,2, a fill factor of 0.35, and a power conversion efficiency of 0.76% under AM 1.5 G (100 mW cm,2) illumination. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 635,646, 2010 [source] Synthesis, characterization, and molecular modeling studies of novel polyurethanes based on 2,2,-[ethane-1,2-diylbis(nitrilomethylylidene)]diphenol and 2,2,-[hexane-1,6-diylbis(nitrilomethylylidene)] diphenol hard segments,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2006A. V. Raghu Abstract Novel polyurethanes (PUs) based on 2,2,-[ethane-1,2-diylbis(nitrilomethylylidene)]diphenol and 2,2,-[hexane-1,6-diylbis(nitrilomethylylidene)]diphenol as hard segments containing four aromatic diisocyanates (4,4,-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) have been prepared. Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, 1H NMR and 13C NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis have been used to determine the structural characterization and thermal properties of the segmented PUs. All the PUs contain domains of both semicrystalline and amorphous structures, as indicated by X-ray diffraction. The acoustic properties have been calculated with the group contribution method. Molecular dynamics simulations have been performed on all the PUs to estimate the cohesive energy density and solubility parameter values, which compare well with the values calculated with the group contribution method. Furthermore, the simulation protocols have been applied to the PUs to produce X-ray diffraction plots to determine the phase morphology of the PUs. The surface properties of the PUs have been estimated from the simulation protocols. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6032,6046, 2006 [source] Sulfonated poly(phenylene oxide) membranes as promising materials for new proton exchange membranesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2006Shifang Yang Abstract Poly(phenylene oxide) (PPO) was sulfonated to different ion exchange capacities (IECs) using chlorosulfonic acid as the sulfonating agent. Tough, ductile films were successfully cast from sulfonated PPO (SPPO) solutions in N -methyl-2-pyrrolidone or N,N -dimethylformamide. The obtained membranes had good thermal stability revealed by thermogravimetric analysis (TGA). Compared with an unsulfonated PPO membrane, the hydrophilicity and water uptake of the SPPO membranes were enhanced, as shown by reduced contact angles with water. The tensile test indicated that the SPPO membranes with IEC ranging from 0.77 to 2.63,meq/g were tough and strong at ambient conditions and still maintained adequate mechanical strength after immersion in water at room temperature for 24,hr. The results of wide-angle X-ray diffraction (WAXD) showed amorphous structures for PPO and SPPO while the peak intensity decreased after sulfonation. The proton conductivity of these SPPO membranes was measured as 1.16,×,10,2,S/cm at ambient temperature, which is comparable to that of Nafion 112 at similar conditions and in the range needed for high-performance fuel cell proton exchange membranes. Copyright © 2006 John Wiley & Sons, Ltd. [source] Ultrasound-guided, high-energy extracorporeal shock-wave treatment of symptomatic calcareous tendinopathy of the shoulderANZ JOURNAL OF SURGERY, Issue 7 2002Christian Jakobeit Background:, The objective of the present study was to test the effectiveness of ultrasound-guided high-energy extracorporeal shock-wave treatment in symptomatic chronic calcareous tendinopathy of the shoulder rotator cuff, and to assess the morphology of the hydroxyapatite deposits before and after this treatment. Methods:, The study involved 80 patients who suffered from calcification of the rotator cuff. These patients were treated with an instrument with electromagnetic induction of shock-waves (Doli-Lithotripter, Dornier, Munich, Germany) under continuous ultrasound location of the treatment focus. The treatments were carried out in one to five sessions at an interval of 4,6 weeks. Each patient received a total of 1800 shock waves in each therapy. The flow density of the energy in the therapy focus was 0.08,0.42 mJ/mm2. Results:, Sixty-eight patients (85%) attained complete freedom from symptoms or only had minimal residual symptoms when stressing their shoulder joint. The calcification suffered by 57 (71.2%) patients was completely resorbed after treatment and partially resorbed in 16 patients (20%). Complete resorption of the calcareous deposits led to freedom from symptoms. In all patients with amorphous calcareous deposits, there was complete resorption of the calcification. Mixed calcareous foci were eliminated in 64.7,77% of the cases, depending on the extent of amorphous structures. Complete resorption was achieved in 44.4% of patients where homogeneous calcareous deposits were >1 cm in size. Conclusion:, Shock-wave treatment in periarthritis of the shoulder is a new and very effective method for symptomatic calcareous tendinopathy. Extracorporeal shock-wave treatment has good prospects of success in any type of calcification. As a non-invasive technique with a high success rate, shock-wave treatment is an alternative to surgical operations in patients who remain symptomatic after exhaustive conservative treatment. [source] | |||||||||||||