bluuebunny/crossref_metadata_2025 huggingface dataset:
The free volume in two untreated, pressure-densified, and CO2 gas exposed polymers from positron lifetime and pressure-volume-temperature experiments
Authors: Dlubek Günter , Pionteck Jürgen , Shaikh Muhamad Qasim , Häußler Liane , Thränert Stefan , Hassan E. M. , Krause-Rehberg Reinhard
Published: August 2014

Changes in the microstructure of the free volume and its temperature dependence in ethylene-norbornene copolymer and bisphenol-A polycarbonate due to densification under pressure and swelling with CO2 gas have been examined using positron annihilation lifetime spectroscopy (PALS) and pressurevolume- temperature (PVT) experiments. Employing the Simha-Somcynsky equation of state the specific hole free and occupied volumes were estimated. From the PALS spectra analyzed with the new routine LT9.0 the size distribution of subnanometre holes and its mean and mean dispersion were calculated. Above Tg, the dispersion mirrors the thermal fluctuations in the free volume. From comparison of PALS and PVT data the specific number of holes was estimated. It was found that the occupied volume has a constant and identical compressibility in the glassy and rubbery state. It shows no memory for the history of the glass and mirrors only the pressure and temperature during the measurement. The change in the total volume due to the pre-treatments of the polymers occurs exclusively in the hole free volume Vf and the relative change in Vf is one order of magnitude larger than in the total volume. PALS data show that the mean hole size and its dispersion in the glassy state is decreased due to densification and increased due to swelling. PVT data show that the volume changes are frozen in the polymer glasses and that, when heating the samples, the volume begins to recover at temperatures ca. 50 K in gas swollen and 20 K in densified polymers below Tg. The PALS data show a corresponding behaviour.
Solvency effect of the dispersion medium on the radical polymerization of styrene in non-aqueous dispersion media
Authors: Ahmad Hasan , Chaki Bijan Mohon , Rahman M. Mahbubor , Miah M.A. Jalil , Tauer Klaus
Published: August 2014

Radical dispersion polymerization of styrene in a non-aqueous media in the presence of a solvent for polystyrene was carried out to study the effect of the solvency of the continuous phase on the polymerization kinetics, the particle morphology, the size and the particle size distribution. Either ethylacetate or cyclohexanone was used as solvent in combination with ethanol as non-solvent. The polymerization kinetics is strongly influenced by the solvency of the continuous phase. The rate of polymerization is reduced in the ethanol-cyclohexanone mixture almost by a factor of two relative to the value obtained in the ethanol-ethylacetate system. On the contrary, variations in the initiator and stabilizer concentration have negligible effects on the polymerization kinetics.
Modelling leading to water entrapment point in thermally driven hydrogelation of methyl cellulose
Authors: Joshi Sunil C. , Lam Y.C. , Bin Chen
Published: August 2014

Development of descriptive models for thermally-driven gelation process for methyl cellulose (MC) solutions is presented in this paper. The available heat absorption profiles obtained using a micro-differential scanning calorimeter (μDSC) during the gelation of MC (SM4000) aqueous solutions with various concentrations were examined. Different mathematical models were considered for fitting the experimental data. Necessary constants for the proposed mathematical formulations were obtained based on the DSC measurements to achieve the most promising fit. Further, analysis based on the mathematical models was performed to describe influence of various parameters for the gelation process, including the total heat, the degree, and the state of gelation. The effect of variations in MC concentrations on these parameters was investigated and the possible mechanisms were highlighted. Proposition was made towards the existence of a water entrapment point on the degree of gelation plots of MC hydrogels and its significance was discussed.
Polypropylene based carbon nanotubes composites: structure and properties
Authors: Tabuani Daniela , Granelli Walter , Camino Giovanni , Claes Michael
Published: August 2014

In the field of polymer nanocomposite materials, carbon nanotubes have attracted lots of research interests in the recent past for their potentialities in improving a wide range of polymer properties. We present here a comprehensive study on polypropylene/carbon nanotube composites evaluating the morphology as well as the thermal behaviour of the prepared systems. Pristine as well as -COOH functionalised carbon nanotubes were taken into account and melt mixed at different weight fractions with PP; the crystallisation characteristics of the material were evaluated by means of DSC and XRD and the thermal behaviour was assessed through TGA analyses. The nanotubes appear to affect significantly the properties of the matrix in a way notably dependent on the functionalization and on the filler amount.
Encapsulation of silica nanoparticles by poly(methyl methacrylate-co-styrene) via emulsion polymerization using dimethylaminoethyl methacrylate
Authors: Barari Mohammad , Sharifi-Sanjani Naser
Published: August 2014

Encapsulation of silica nanoparticles was performed by emulsion copolymerization of methyl methacrylate (MMA) and styrene (St) using dimethylaminoethyl methacrylate (DM) as an auxiliary monomer. The emulsion polymerization was performed in the presence of silica nanoparticles as the seed to obtain encapsulated silica nanoparticles with polymer content and average particle sizes ranged from 35 wt. % to 85 wt. % and 114 to 272 nm respectively. Electrostatic attraction between anionic surface of silica beads and cationic amino groups of DM is the main driving force for the encapsulation of the silica nanoparticles. The influence of MMA, St and DM concentration on the coating of the silica nanoparticles was studied. It was demonstrated that DM has an important role in stabilizing the system. Transmission electron microscopy showed that coreshell structures with silica particles as core were coated with the polymer, of which the amount and morphology were influenced by the total monomer concentration and molar ratio of MMA to St. Zeta potential measurement confirmed the presence of DM on the surface of composite particles. Thermogravimetric analysis showed that the incorporation of silica in polymer matrix results in an enhancement of thermal stability in the encapsulated products. Differential scanning calorimetry studies indicated that the glass transition temperature of encapsulated particles can be either higher or lower than those of the pure terpolymer counterpart, depending on the DM content of the polymer shell. The products were also characterized by FT-IR spectroscopy.
Mechanical and thermal properties of PP/compatibilized PP/acid treated SWNTs nanocomposites: Effect of different acid treatment times
Authors: Ahangari Morteza Ghorbanzadeh , Fereidoon Abdolhosein , Saedodin Seyfolah
Published: August 2014

In the present work, the effect of different acid treatment times of singlewalled carbon nanotubes (SWNTs) on the mechanical and thermal properties of polypropylene (PP)/maleated polypropylene (PP-g-MA) nanocomposites was investigated. The acid treatment process was based on a mixture of concentrated sulphuric and nitric acids. The SWNTs were treated with the acid mixture for 1, 3, and 6 h. FTIR, Raman spectroscopy and TEM revealed the values of carboxylic groups, graphitization and morphology of acid treated SWNTs, respectively. The thermal and mechanical properties and the morphology of nanocomposites were investigated by tensile tests, DMTA, DSC, and SEM.
Surface modification of carbon nanofibers (CNFs) by plasma polymerization of methylmethacrylate and its effect on the properties of PMMA/CNF nanocomposites
Authors: Guadalupe Neira-Velázquez María , Ramos-de Valle Luis Francisco , Hernández-Hernández Ernesto , Zapata-González Ivan
Published: August 2014

Carbon nanofibers (CNFs) were modified via plasma polymerization using methyl methacrylate (MMA) as monomer and used as reinforcements for polymethyl methacrylate (PMMA). Conditions of the MMA plasma process in a specially designed reactor and plasma-polymerized methyl methacrylate (PPMMA) films were studied. The study involved varying the process time at a constant plasma power of 100 W and a constant MMA flow rate (0.15 cm3 per min). Nanocomposites of PPMMA-coated CNFs and PMMA were prepared with 0.5, 1.0, 2.0, 4.0 and 8.0 %wt of treated CNFs. The effect of the MMA plasma on the CNFs was analyzed. Dispersion of the modified CNFs was evaluated in several solvents. The results confirmed a change in hydrophobicity of the treated CNFs. The inclusion of treated CNFs exhibited substantial impact on the properties of the PMMA/CNF nanocomposites. The thermal and mechanical properties of the PMMA/CNF composites were examined. It was found that the thermal stability increased by about 8% and the Young´s modulus significantly enhanced by as much as 178% when compared to PMMA with no CNFs.
Polypropylene + Polystyrene Blends with a Compatibilizer. Part 2. Tribological and Mechanical Properties
Authors: Brostow Witold , Holjevac Grguric Tamara , Olea-Mejia Oscar , Pietkiewicz Dorota , Rek Vesna
Published: August 2014

Styrene-ethylene/butylene-styrene (SEBS) block copolymer was used as the compatibilizer for PP + PS blends. We have investigated effects of the presence of SEBS on tribological and mechanical properties; dynamic mechanical analysis (DMA) was also performed. Since the copolymer causes formation of smaller particles of the dispersed PS phase in PP matrix blends, there is improved energy transmission and dissipation resulting in higher impact strength. The SEBS additive is relatively soft and causes a decrease in stress at break but an increase in elongation at break in tensile testing. In most cases the friction of the compatibilized blends is higher although in PS-rich blends we find a decrease. Scratch testing shows a change in wear mechanisms when SEBS is added to PP/PS. In uncompatibilized blends we observe adhesive wear, with crazes formed in the middle of the wear track. A compatibilized blend shows more ductile behavior and ploughing wear.
Effects of solvents on post-irradiation grafting of styrene onto fluoropolymer films
Authors: Napoleão Geraldes Adriana , Augusto Zen Heloísa , Fernandes Parra Duclerc , Perez Ferreira Henrique , Benévolo Lugão Ademar
Published: August 2014

Due to the interest in the development of low cost membranes with similar capabilities to Nafion®, grafting of styrene on fluorinated polymers by simultaneous irradiation and pre-irradiation methods at high temperature (higher than 50 °C) followed by sulfonation has been a process studied broadly. However, there is very little information about grafting yield at room temperature after simultaneous irradiation. Previous works reported that the surface morphology of the styrene grafts has showed an uneven profile under the studied conditions. This work aims to evaluate the grafting of styrene onto these films after simultaneous irradiation (in post-irradiation condition), using different solvent in periods until 28 days at room temperature. Films of poly(tetrafluoroethylene) (PTFE) and poly(vinylidene fluoride) (PVDF) were immersed in styrene/toluene 1:4 or styrene/methanol 1:4 and then submitted to gamma radiation at 40 and 80 kGy doses. The degree of grafting (DOG) was determined gravimetrically and physical and chemical changes were evaluated by infrared spectroscopic analysis (FTIR), differential scanning calorimeter analysis (DSC), thermogravimetric analysis (TGA), and also by scanning electron microscopy (SEM). For PTFE films, the highest DOG was achieved using toluene as solvent while for PVDF films, the highest DOG was achieved with methanol. Surface images of the grafted films by SEM technique have presented a strong effect of the solvents on the films morphology. Finally, PVDF-g-PS in styrene/methanol film revealed higher DOG, although the surface showed small cavities and discontinuities. On the contrary, the surface of PTFE-g-PS in styrene/toluene presented homogeneous surface.
The state of clay dispersion in maleated polypropylene /organoclay nanocomposites via dielectric spectroscopy measurements
Authors: Wang Yeh , Huang Syh-W. , Guo Jiang-Y.
Published: August 2014

Dielectric spectroscopy is a powerful method that allows the study of dynamics of polymers in a wide frequency range. In this work, the state of clay dispersion was related to the dielectric properties of the polymer nanocomposites based on organoclay filled maleated polypropylene (PPgMA). Fully and partially exfoliated samples were prepared through powered sonication and melt blending, respectively. Though two mechanical relaxations were revealed from dynamical mechanical analysis (DMA), only a single high-temperature process resulting from interfacial polarization was observed in broadband dielectric measurements. Dielectric dispersion parameters that appear sensitive to clay loading and degree of exfoliation were identified. The nanomorphology was primarily reflected in the Maxwell-Wagner characteristic relaxation frequency value, fp, where samples with higher degree of exfoliation showed lower relaxation rate. The relaxation time constant, which is the reciprocal of 2πfp, can be correlated with mean distance of clay layer separation in the nanocomposites and therefore provides additional information on exfoliation of clay platelets. A clear evolution of the relaxation activation energy with the degree of clay dispersion was also observed. The experimental results indicated that sonicated samples with fully exfoliated clay platelets yielded the longer relaxation time and the higher activation energy compared to their partially exfoliated counterparts.
Colloidal and physicochemical characterization of proteincontaining poly(lactide-co-glycolide) (PLGA) microspheres before and after drying
Authors: Kalaji Nader , Sheibat-Othman Nida , Saadaoui Hassan , Elaissari Abdelhamid , Fessi Hatem
Published: August 2014

In the present work, the double emulsion (W/O/W) method was used to microencapsulate a protein model (Bovine Serum Albumin) in a biodegradable polymer poly(lactide-co-glycolide) (50:50) (PLGA). Colloidal and physicochemical characterization of PLGA based microspheres was investigated after their “crude” preparation and after drying and redispersion processes. Particle morphology and size were studied by scanning electron microscopy and by laser diffraction analysis. Electrokinetic study and colloidal stability were also studied as a function of pH and salinity of the medium. Atomic force microscopy (AFM) was used to study the surface properties. It was found that smooth microspheres were obtained after the drying process. The Atomic force microscopy results of microspheres stored for one month in water show softness and surface irregularity caused by the microspheres degradation. The colloidal stability of theses microspheres is mainly governed by repulsive electrostatic interaction due to the PLGA charge. The used amount of stabilizing agent poly(vinyl alcohol) (PVA) is low enough to ensure the sterical stabilization. Drying process has no effect on the surface properties and colloidal stability of the prepared microspheres.
Polymer concretes improved by fiber reinforcement and gamma irradiation
Authors: Martínez-Barrera Gonzalo , Martínez-Hernández Ana Laura , Velasco-Santos Carlos , Brostow Witold
Published: August 2014

The well-known key problem with concrete is that its compressive strength and the compression modulus are insufficient for a variety of applications. Our polymer concrete (PC) consists of an unsaturated polyester resin as the polymeric matrix, silica sand as the inorganic aggregate, plus atactic polypropylene (PP) fibers. A further property improvement can be achieved by gamma irradiation and we apply here two methods. The first method consists in irradiation of PP fibers first and then adding them to the PC. The second route consists in irradiation of PC after inclusion of PP fibers. Along both routes we have applied the radiation at dosages ranging from 5 to 150 kGy. In the second route irradiation of silica sand results in larger contact areas of surfaces with PP fibers and with the polyester resin-as seen in scanning electron microscopy. The second route provides compressive properties which is better by a factor of two or three (depending on the irradiation dose) than the first one.
Nanostructured hybrid materials obtained by UV curing and sol-gel processes involving alkoxysilane groups
Authors: Amerio Ezio , Malucelli Giulio , Sangermano Marco , Priola Aldo
Published: August 2014

Novel hybrid organic-inorganic coatings were obtained by photopolymerization and subsequent thermally induced condensation through solgel processes. Both radical (methacrylic) and cationic (epoxy) resins were considered as precursors of the organic phase; tetraethoxysilane (TEOS) was the precursor of the inorganic phase. The effect of the presence of a coupling agent was investigated. Real-time FT-IR analysis was used for evaluating the kinetics of photopolymerization. 29Si-NMR spectroscopy was used in order to evaluate the degree of condensation of alkoxysilane groups. The results showed the prevalence of Q3 e T2 structures indicating an incomplete condensation of the alkoxysilane groups. T1 and Q1 signals are not present, thus indicating that for each Si atom, two or more alkoxysilane groups take part to the condensation reaction. FE-SEM analyses evidenced a nanometric organization of the inorganic domains in the polymer matrix. The addition of the coupling agent was found to influence the morphology of the hybrid systems. DMTA and TGA analyses revealed an increase of the Tg values and of the thermal stability by increasing the coupling agent and TEOS content.
Competing effect of shear and β-nucleating agent on the crystallization of injection-molded iPP
Authors: Zheng Guoqiang , Hao Xiaoqiong , Wang Yaming , Liu Chuntai , Zhang Qinxing , Shen Changyu , Chen Jingbo , Peng Xiangfang
Published: August 2014

In this study, crystallization at different depth in the injection-molded iPP, filled with β-nucleating agent (β-NA), was investigated. According to WAXD result, one observes that the fraction of β-crystals unevenly distributes along the depth of the injection-molded parts. For iPP with lower content of β- NA, larger amount of β-crystals near the surface is shear induced; meanwhile, for the parts with higher content of β-NA, larger amount of β crystals away from the surface is β-NA induced. From the results, it could be suggested that the traditional role of nucleation agent, i.e., heterogeneous nucleation, under complex thermo-mechanical conditions during injection molding, might be suppressed.
Synthesis and property studies of oligomer obtained from the reaction of 4-vinylbenzocyclobutene and styrene with divinyl tetramethyl disiloxane-bisbenzocyclobutene
Authors: Xu Yewei , Zhu Fanghua , Xie Liqin , Yang Junxiao , Zhang Lin , Xie Rugang
Published: August 2014

Radical copolymerization of 4-vinylbenzocyclobutene (VBCB) with styrene (St) afforded the copolymer (4-vinylbenzocyclobutene-co-styrene) (VBCBSt). Reaction of VBCB-St and divinyl tetramethyl disiloxane-bisbenzocyclobutene (DVSBCB) gave the oligomer (VBCB-St-DVSBCB), which was subsequently subjected to the cure reaction. The structures of VBCB-St and oligomer (VBCB-St- DVSBCB) were characterized by FTIR and 1H NMR, which are in agreement with the proposed structures. Molecular weights of the synthesized polymers were estimated by gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) showed that VBCB-St exhibited glass transition temperature (Tg > 95 °C) however it is not the case for the oligomers (VBCB-St-DVSBCB). TG measurements indicated that the polymers had the good thermal stability with decomposition temperatures (TD > 370 °C). The polymer resin possessed good film planarization in the AFM images and the process of oligomer curing on a wafer without fusion and flow. These results indicated that the oligomer (VBCB-St- DVSBCB) is a promising film material with a relatively low cost.
Variable surface properties of PTFE foils
Authors: Švorčík Václav , Řezníčková Alena , Kolská Zdenka , Slepička Petr , Hnatowicz Vladimír
Published: August 2014

Surface properties of commercially available polytetrafluoroethylene (PTFE) foils of different thicknesses were examined using three different methods: AFM, study of a electrokinetical ζ-potential and measurement of a contact angle by goniometry. It was found that the front and back sides of the foils exhibit different surface morphology and roughness, different values of the ζ-potential and contact angle. The contact angle and the ζ-potential are decreasing functions of the foil thickness.
Synthesis and properties of poly(arylene imino) containing fluorenone group (PIKF)
Authors: Zhang Lin , Chang Guanjun , Xu Zhen , Miao Lubin , Xu Yi , Hu Hongju , Luo Xuan , Lin Runxiong
Published: August 2014

A series of novel poly(arylene imino) containing fluorenone group (PIKF) have been synthesized via palladium-catalyzed polycondensation. The thermal properties of PIKF are detected by thermal behavior (TG) and differential scanning calorimetry (DSC). UV-vis absorption spectra, photoluminescence are investigated. PIKF exhibit good thermal stability and high Tgs(>200 °C ). The optical properties of PIKF show that PIKF are interesting materials for further investigations to be presented as possible candidates for use as an electron transport layer (n-type) in multilayer LEDs.
The morphology and non-isothermal crystallization kinetics of PET/BaSO4 hybrid fibre
Authors: Gong Maoming , Zheng Guo , Xu Jinyun , Sun Yu
Published: August 2014

The addition of BaSO4 whose mass fraction was less than 0.052%, could improve the mechanical property and thermal stability of the fibre apparently. It was found that, the smoothness of the hybrid fibre was changed by BaSO4 appreciably, though allowable in actual production; The BaSO4 did not obviously affect the crystallization index ( a ) and the relative degree of crystallization. With the content of BaSO4 increasing, the crystallization rate firstly became smaller slightly and then restored to the original level at the primary crystallization stage, but the crystallization rate revealed a small fluctuation at the secondary crystallization stage. In addition, the Ozawa equation was fit for pure PET well, and the Mo equation was fit for pure and hybrid PET.
Flow induced crystallization of LDPE nanocomposites: A rheological and morphological characterization
Authors: Azzurri Fiorenza , Stagnaro Paola , Conzatti Lucia , Cavallo Dario , Repetto Luca , Scatto Marco , Andreotti Leonardo , Coiai Serena
Published: August 2014

The flow induced crystallization behaviour of a LDPE:PE-g-MA:D72T 90:9:1 nanocomposite has been investigated by in-situ Rheo-SALS technique and data have been compared with those obtained from a reference LDPE:PE-g-MA 90:9 sample. Rheo SALS results, confirming thermal analysis findings, indicate that under mild shear flow fields the organoclay exhibits a negligible nucleating effect. Both nucleation density and, as a consequence, crystallization rate, are not appreciably affected by the application of external flow field for both the examined systems, revealing that no evident synergic effects between the organoclay and the shear flow are present. On the other hand, Rheo SALS analysis indicates that the nanocomposite submitted to flow exhibits a higher level of crystal orientation. TEM morphological analyses support this observation suggesting that the orientation of the nanofiller along the flow direction templates the growth of oriented crystals.
Unconventional microstructure of maleic anhydride copolymers in condensed and dissolved states
Authors: Filimoshkin Anatoliy , Berezina Elena , Manzhay Vladimir , Kuchevskaya Alexandra , Ivanov Alexander
Published: August 2014

A novel type of protopropic tautomerism proceeds in macromolecules of binary copolymers of maleic anhydride (MA) with vinyl acetate (VA) and vinyl chloride (VC) giving rise to spontaneous formation of dynamic micro structural heterogeneity which consists of several tautomeric forms: succinic anhydride rings, VC and VA units along with unforeseen enol (en) and dienol (den) furan derivatives (33 mol%). The arising hydrogen bonds close the ring generating quasi-aromatic structures simultaneously. The en and den tautomers form charge-transfer complexes with O- and N- nucleophiles. Mechanism of MA radical copolymerization with VC including polyaddition of molecular monomer complexes both in the ground state and in their biradical resonance structures has been proposed. The investigations were carried out using infrared spectroscopy (IR-), electron, nuclear magnetic resonance spectroscopy (1Н and 13С NMR), differential thermo analysis, mathematical microstructure modelling etc.
Microwave-assisted Wurtz coupling of methylphenyldichlorosilane in solvent-free conditions
Authors: Sacarescu Gabriela , Simionescu Mihaela , Harabagiu Valeria , Sacarescu Liviu
Published: August 2014

This communication describes the synthesis of polymethylphenylsilane by the microwave-assisted coupling of methylphenyldichlorosilane using metallic sodium in solvent free conditions. The instant heating melts the sodium particles within the liquid methylphenyldichlorosilane and the polymerization reaction is achieved in minutes with total consumption of the monomer. The process is carried out in a high performance microwave reactor using the closed vessel operating facility which ensures control of the reaction parameters and highly reproducible results.
Effects of organoclay on morphology and mechanical properties in acrylonitrile-butadiene-styrene/polyamide 6/ organoclay ternary nanocomposites
Authors: Yan Wei , Qin Shuhao , Guo, Jianbing , He Min , Zhang Minmin , Yu Jie
Published: August 2014

In this article, polyamide 6(PA6)/organoclay masterbatch were prepared by melt mixing, and then acrylonitrile-butadiene-styrene(ABS)/polyamide 6(PA6)(70/30,w/w) nanocomposites were prepared by the melt mixing of PA6, ABS and organoclay. The effect of organoclay platelets on morphology and mechanical properties of ABS/PA6/organoclay ternary nanocomposites had been investigated by wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM), scanning electron microscopy (SEM) and mechanical properties testing. Morphology analysis revealed that organoclay platelets were selectively dispersed and exfoliated in PA6 phase, but some were located in interface of PA6 and ABS phase. The droplet size of PA6 dispersed phase were gradually reduced less than 4 phr organoclay, then the dispersed domain size became unchanged with the addition of various organoclay. It suggested the organoclay can compatibilize the ABS/PA6 blend nanocomposite. Moreover, the flexural strength and modulus increase with increasing organoclay content, but the tensile strength became maximal at 3 phr organoclay. The organoclay has no effect on impact strength of ABS/PA6 blend nanocomposite.
Synthesis and characterization of a novel wound dressing by PVP/ PAANa/chitosan with semi-interpenetrating polymer network structure
Authors: Wu Ying , Yang Qing , Gi Yali , Zhang Yueting
Published: August 2014

A novel hydrogel wound dressing with semi-interpenetrating polymer network structure (semi-IPN) was prepared by radical polymerization of acrylic acid with potassium persulfate (K2S2O8) as initiator and N, N'-methylenebisacrylamide (MBA) as cross-linking agent in the presence of chitosan (CTS) and polyvinyl pyrrolidone (PVP). Hydrogels were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM displayed semi- IPN hydrogels' creased surface with some scale-like wrinkles, thus improving the absorptive capability which has been considered as a most important characteristic of wound dressings. It was found that the content of cross-linking agent and the mass ratio of PVP and CTS had much influence on the mechanical properties of the hydrogel, varying from brittle plastics to elastomer due to the different degrees of cross linking. Since tensile strength is partly in inverse ratio to the hydrogel absorbent capability, the article offers an analysis of varying material proportion in order to obtain an optimum properties of the hydrogel wound dressing .
The variation of comonomers feeding profile to design the distribution of chains composition for the optimization of the mechanical properties in copolymer systems
Authors: Arnez-Prado Alvaro H. , González-Ortiz Luis J. , Aranda-García Francisco J. , Jasso-Gastinel Carlos F.
Published: August 2014

Semicontinuous seeded emulsion copolymerizations, using 5 different types of feeding profiles of comonomers (styrene/butyl acrylate, S/BA) were carried out, to vary in a gradual manner the composition of the copolymer chains formed throughout the reactions (gradient composition copolymer, GCC). For comparison, equivalent core-shell type polymeric materials were synthesized in two stages (TS). In all reactions, the S/BA global mass ratio was: 70/30. To estimate the weight composition distribution (WCD) of the copolymer chains, the cumulative styrene content in the polymer mass was followed throughout the reaction (1H-NMR). Average molecular weights were determined using SEC. The differences in mechanical performance were established, carrying out a mechanodynamic (DMA), and mechanostatic characterization (stress-strain at several temperatures and, Izod testing). The area under the loss modulus curve (LA) was correlated with Izod impact strength, showing the damping superiority of the GCCs over the T-S material. At all tested temperatures (between 25 and 70 °C), the GCC materials exhibited yielding and plastic deformation, while the T-S material presented brittle fracture in that temperature interval. The WCDs were used to elucidate the differences in mechanical behaviour among GCC materials. The feeding profile variation in combination with the WCD analysis represents a novel methodology to produce tailor made copolymers.
New Tone Reservation Technique for Peak to Average Power Ratio Reduction
Authors: Wilharm Joachim , Rohling Hermann
Published: August 2014

In Orthogonal Frequency Division Multiplexing (OFDM) the transmit signals have a highly fluctuating, non-constant envelope which is a technical challenge for the High Power Amplifier (HPA). Without any signal processing procedures the amplitude peaks of the transmit signal will be clipped by the HPA resulting in out-ofband radiation and in bit error rate (BER) performance degradation. The classical Tone Reservation (TR) technique calculates a correction signal in an iterative way to reduce the amplitude peaks. However this step leads to a high computational complexity. Therefore, in this paper an alternative TR technique is proposed. In this case a predefined signal pattern is shifted to any peak position inside the transmit signal and reduces thereby all amplitude peaks. This new procedure is able to outperform the classical TR technique and has a much lower computational complexity.
Thickness Optimization for Petroleum Coke in Microwave Dehydrating Based on the Analysis of Dynamic Absorption Efficiency
Authors: Shang Xiaobiao , Chen Junruo , Peng Jinhui , Chen Hua , Zhang Weifeng , Guo Shenghui , Chen Guo
Published: August 2014

An analytical approach is proposed to optimize the thickness of petroleum coke for achieving maximum microwave power absorption in microwave heating based on analysis of reflection loss (RL). The microwave RL of the petroleum coke layer was studied over the moisture content range of 1%–5% at 20 °C and the petroleum coke (10% moisture content) in the temperature range of 20 to 100 °C at 2.45 GHz. The results show that RL depends sensitively on the thickness of the petroleum coke and the absorption peak shifts towards a larger thickness as the moisture content of the petroleum coke increases. There exists a matching thickness corresponding to the maximum microwave absorption, the maximum absorbing peak decreases when the thickness of petroleum coke exceeds the matching thickness. We also show that the absorption peak is found to move towards a smaller thickness region with increasing petroleum coke temperature.
The Cyclic Carburization Process by Bi-velocity Method
Authors: Wierzba Bartek , Romanowska Jolanta , Kubiak Krzysztof , Sieniawski Jan
Published: August 2014

The paper presents numerical analysis of the cyclic external fluxes on diffusion process. It is shown, that the cycles characteristics strongly affects the concentration profiles and stress distribution in material. Calculations were performed using the bi-velocity method with the stress field factor. Moreover, the more general model describing the cyclic carburization process influenced by self stress was formulated. Numerical solutions were obtained assuming composition dependent diffusion coefficients. The results of simulation were compared with the experimental data. The model proposed in this paper may be applied to other diffusion controlled processes with the external flux of the diffusive component.
Reframing Race and Place
Authors: Geiger Andrea
Published: August 2014

This article looks at Japanese attitudes toward indigenous people in the North American West and their place on the land that Japanese immigrants hoped to settle and develop. Examples of popular conceptions and of Japanese diplomats’ efforts to position Japanese settlers in reference to other settlers and indigenous people are not intended as a comprehensive survey of Japanese immigrant attitudes but as a few examples indicating the important work remaining for scholars to bridge the gap between immigration and indigenous history. They invite further work on the interrelations between marginalized groups and a more complex understanding of racism and immigration.
Community and Measured Militancy
Authors: Barajas Frank P.
Published: August 2014

The Ventura County Community Service Organization (CSO) formed in 1958 to empower the Mexican-origin community. This article traces the strategies the organization employed to build community solidarity and political engagement. The CSO established a significant voice in local, state, and national issues.
Reasons (not) to Spend a Few Billions More on EHRs: How Human Factors Research Can Help
Authors: Aimé X. , Declerck G. ,   Section Editors for the IMIA Yearbook Section on Human Factors and Organizational Issues
Published: August 2014

Objectives: To select best medical informatics research works published in 2013 on electronic health record (EHR) adoption, design, and impact, from the perspective of human factors and organizational issues (HFOI).

Methods: We selected 2,764 papers by querying PubMed (Mesh and TIAB) as well as using a manual search. Papers were evaluated based on pre-defined exclusion and inclusion criteria from their title, keywords, and abstract to select 15 candidate best papers, finally reviewed by 4 external reviewers using a standard evaluation grid.

Results: Five papers were selected as best papers to illustrate how human factors approaches can improve EHR adoption and design. Among other contributions, these works: (i) make use of the observational and analysis methodologies of social and cognitive sciences to understand clinicians’ attitudes towards EHRs, EHR use patterns, and impact on care processes, workflows, information exchange, and coordination of care; (ii) take into account macro- (environmental) and meso- (organizational) level factors to analyze EHR adoption or lack thereof; (iii) highlight the need for qualitative studies to analyze the unexpected side effects of EHRs on cognitive and work processes as well as the persistent use of paper.

Conclusion: Selected papers tend to demonstrate that HFOI approaches and methodologies are essential to bridge the gap between EHR systems and end users, and to reduce regularly reported adoption failures and unexpected consequences.
Big Data and Smart Health Strategies: Findings from the Health Information Systems Perspective
Authors: Cuggia M. , Toubiana L. ,   Section Editors for the IMIA Yearbook Section on Health Information Systems
Published: August 2014

Objectives: To summarize excellent current research in the field of Health Information Systems.

Method: Creation of a synopsis of the articles selected for the 2014 edition of the IMIA Yearbook.

Results: Four papers from international peer reviewed journals were selected and are summarized.

Conclusions: Selected articles illustrate current research regarding the impact and the evaluation of health information technology and the latest developments in health information exchange.
Managing Free Text for Secondary Use of Health Data
Authors: Griffon N. , Charlet J. , Darmoni S. J. ,   Section Editors for the IMIA Yearbook Section on Knowledge Representation and Management
Published: August 2014

Objective: To summarize the best papers in the field of Knowledge Representation and Management (KRM).

Methods: A comprehensive review of medical informatics literature was performed to select some of the most interesting papers of KRM and natural language processing (NLP) published in 2013.

Results: Four articles were selected, one focuses on Electronic Health Record (EHR) interoperability for clinical pathway personalization based on structured data. The other three focus on NLP (corpus creation, de-identification, and co-reference resolution) and highlight the increase in NLP tools performances.

Conclusion: NLP tools are close to being seriously concurrent to humans in some annotation tasks. Their use could increase drastically the amount of data usable for meaningful use of EHR.
Restraint of the G2/M Transition by the SR/RRM Family mRNA Shuttling Binding Protein SNXAHRB1 in Aspergillus nidulans
Authors: James Steven W , Banta Travis , Barra James , Ciraku Lorela , Coile Clifford , Cuda Zach , Day Ryan , Dixit Cheshil , Eastlack Steven , Giang Anh , Goode James , Guice Alexis , Huff Yulon , Humbert Sara , Kelliher Christina , Kobie Julie , Kohlbrenner Emily , Mwambutsa Faustin , Orzechowski Amanda , Shingler Kristin , Spell Casey , Anglin Sarah Lea
Published: August 2014

Control of the eukaryotic G2/M transition by CDC2/CYCLINB is tightly regulated by protein–protein interactions, protein phosphorylations, and nuclear localization of CDC2/CYCLINB. We previously reported a screen, in Aspergillus nidulans, for extragenic suppressors of nimX2cdc2 that resulted in the identification of the cold-sensitive snxA1 mutation. We demonstrate here that snxA1 suppresses defects in regulators of the CDK1 mitotic induction pathway, including nimX2cdc2, nimE6cyclinB, and nimT23cdc25, but does not suppress G2-arresting nimA1/nimA5 mutations, the S-arresting nimE10cyclinB mutation, or three other G1/S phase mutations. snxA encodes the A. nidulans homolog of Saccharomyces cerevisiaeHrb1/Gbp2; nonessential shuttling messenger RNA (mRNA)-binding proteins belonging to the serine-arginine-rich (SR) and RNA recognition motif (RRM) protein family; and human heterogeneous ribonucleoprotein-M, a spliceosomal component involved in pre-mRNA processing and alternative splicing. snxAHrb1 is nonessential, its deletion phenocopies the snxA1 mutation, and its overexpression rescues snxA1 and ΔsnxA mutant phenotypes. snxA1 and a second allele isolated in this study, snxA2, are hypomorphic mutations that result from decreased transcript and protein levels, suggesting that snxA acts normally to restrain cell cycle progression. SNXAHRB1 is predominantly nuclear, but is not retained in the nucleus during the partially closed mitosis of A. nidulans. We show that the snxA1 mutation does not suppress nimX2 by altering NIMX2CDC2/NIMECYCLINB kinase activity and that snxA1 or ΔsnxA alter localization patterns of NIMECYCLINB at the restrictive temperatures for snxA1 and nimX2. Together, these findings suggest a novel and previously unreported role of an SR/RRM family protein in cell cycle regulation, specifically in control of the CDK1 mitotic induction pathway.
MINERAIS CONTAMINANTES DO CAULIM DA MINA IPIXUNA, NO ESTADO DO PARÁ: CARACTERÍSTICAS E INTERFERÊNCIAS NO BENEFICIAMENTO MINERAL
Authors: Sabedot Sydney , KAUTZMANN RUBENS MÜLLER , PETTER CARLOS OTÁVIO , SAMPAIO CARLOS HOFFMANN
Published: August 2014

A mina Ipixuna extrai caulim sedimentar e produz matéria-prima final para a indústria do papel. O minério varia devido a presença de minerais contaminantes. Whiteness, yellowness e composição química são parâmetros importantes no processamento mineral. Visualmente, minério com cor vermelha ou amarela é descartado, e com cor clara é aproveitado. Nesta pesquisa, as análises com espectrofotometria, estereomicroscopia e mineralogia com amostras de minério mostraram que a mineralogia contaminante é um indicador importante na tomada de decisão sobre o beneficiamento. Verificou-se que blocos com cor amarela e com alto teor de ferro, podem gerar produto final com qualidade para o papel, quando o principal mineral contaminante é a goethita, removida na separação magnética e branqueamento no químico.
IMPORTÂNCIA DA VELOCIDADE DE CORTE NA OTIMIZAÇÃO DA ETAPA DE POLIMENTO DE ROCHAS ORNAMENTAIS
Authors: Camargo Jefferson Luiz , Silveira Leonardo Lyrio , Dorigo Wana Gaburo , Artur Antônio Carlos
Published: August 2014

A etapa de polimento de rochas ornamentais ocorre em politrizes, as quais podem ser semi-automáticas ou automáticas. Em ambas as máquinas, a velocidade de rotação do satélite é invariável, e, por consequência, a velocidade de corte, que é a distância percorrida por um rebolo abrasivo em função do tempo, permanece constante. A possibilidade de se alterar a velocidade com que o rebolo abrasivo passa sobre a superfície da chapa de rocha pode permitir uma otimização desse processo. Para esta pesquisa foram definidas 24 situações operacionais distintas, nas quais variou-se a pressão de carregamento (1 e 2 kgf/cm2), velocidade de rotação de satélite (300, 400, 500 e 600 rpm) e a exposição do satélite sobre a rocha (1, 2 e 3). Para isso, foi instalado um inversor de frequência em uma politriz semi-automática que possibilitou a variação da velocidade de rotação de satélite para realização dos experimentos. Assim, foram realizados os testes de polimento, sendo cada rocha submetida a 10 sequências de rebolos abrasivos do tipo magnesiano, a saber: 24, 36, 60, 120, 220, 400, 600, 800, 1200 e lustro, totalizando 720 amostras. Os resultados mostraram que no sistema tribológico existente no polimento de rochas ornamentais a variável rocha atua como elemento ativo, influenciando no desgaste do rebolo abrasivo e exibindo brilho de acordo com as propriedades petrográficas.
AVALIAÇÃO DA UTILIZAÇÃO DA ENERGIA DE MICRO-ONDAS PARA PROCESSO DE REMOÇÃO DO TEOR DE FÓSFORO CONTIDO NO MINÉRIO DE FERRO
Authors: Silva Leonardo Martins da , Nascimento Marisa , Castro José Adlson de , De oliveira da mota Izabel
Published: August 2014

O elemento fósforo quando encontrado nos aços em teores acima de 0,04% torna-se nocivo à qualidade do aço. No processo tradicional de remoção elemento fósforo contido no gusa, baixos teores somente são obtidos com uso massivo de oxigênio e alto volume de escória, o que torna o processo altamente custoso economicamente e ambientalmente gerando grandes quantidades de resíduos que devem ser posteriormente tratados. Uma alternativa viável para minimizar os efeitos do fósforo nos processos de obtenção do aço é o pré-tratamento das frações do minério de alto fósforo logo no seu beneficiamento. O processo de lixiviação ácida é considerado o processo mais econômico para a reação de desfosforação do minério de ferro, todavia dependendo da forma com que o elemento fósforo esteja contido no minério de ferro o mesmo dependerá da adição de energia adicional para sua liberação. O presente trabalho objetiva-se estudar o efeito da energia de micro-ondas na redução do teor de fósforo contido no minério de ferro. Através do processo de difração de Raios-X utilizando o método de Rietveld foi possível demonstrar a composição mineralógica da amostra de minério de ferro e através do software Thermocalc® foi possível identificar a forma estrutural que se encontra o elemento fósforo no minério de ferro. Pelo método estatístico de delineamento composto central rotacional foi possível identificar as melhores condições de utilização da energia de micro-ondas para redução do teor do elemento fósforo e microscopia eletrônica de varredura (MEV) foi possível analisar a estrutura do minério após seu tratamento com energia de microondas.
ALTERNATIVE BINDERS TO BENTONITE FOR IRON ORE PELLETIZING: PART I: EFFECTS ON PHYSICAL AND MECHANICAL PROPERTIES
Authors: Sivrikaya Osman , Arol A. I.
Published: August 2014

The use of conventional bentonite binder is favorable in terms of mechanical and metallurgical pellet properties, however, because of its acid constituents bentonite is considered as impurity especially for iron ores with high acidic content. Therefore, alternative binders to bentonite have been tested. Organic binders are the most studied binders and they yield pellets with good wet strength; they fail in terms of preheated and fired pellet strengths. This study was conducted to investigate how insufficient pellet strengths can be improved when organic binders are used as binder. The addition of a low-melting temperature and slag bonding/strength increasing constituent (free in acidic contents) into pellet feed was proposed. Addition of boron compounds such as colemanite, tincal, borax pentahydrate, boric acid together with organic binders such as CMC, starch, dextrin and some organic based binders, into iron oxide pellet was tested. Wet and thermally treated pellet physical-mechanical qualities (balling - moisture content - size - shape - drop number - compressive strengths - porosity - dustiness) were determined. The results showed that good quality wet, dry, preheated and fired pellets can be produced with combined binders (an organic binder plus a boron compound) when compared with bentonite-bonded pellets. While organic binders provided sufficient wet and dry pellet strengths, the boron compounds provided the required preheated and fired pellet strengths at even lower firing temperature. Especially, the contribution of boron compound addition is most pronounced for hematite pellets which do not have strengthening mechanism through oxidation like magnetite pellets during firing. Therefore, addition of boron compound is beneficial to recover the low physical-mechanical qualities of pellets produced with organic binders through slag bonding mechanism. Furthermore, lowering the firing temperature thanks to low-melting boron compounds will be cost-effective for firing part of the pelletizing plants.
CONSIDERAÇÕES PRÁTICAS SOBRE CONTROLE AVANÇADO DE PROCESSO APLICADO A MOINHO DE BOLAS
Authors: Gedraite Rubens , Neiro Sérgio Mauro da Silva , Morais Aniel S. , Vieira Leonardo , Rodrigues Lucas Arthur
Published: August 2014

A aplicação de estratégia de controle avançado em moinhos de bolas tipicamente usados em usinas de beneficiamento de minério é um tema cuja importância vem crescendo sistematicamente. Tal fato é justificado pelo aumento de produção, melhoria da qualidade do produto final, economia de energia e menor desgaste do revestimento interno do moinho. O sistema de controle avançado apresentado neste trabalho contempla o emprego de controlador multivariável acoplado a sistema de controle regulatório, que permite ao moinho alcançar condições ótimas de operação de acordo com os critérios técnicos estabelecidos como premissa de projeto. A implantação do sistema de controle avançado foi realizada de forma simples e rápida, permitindo comunicação direta com o sistema de controle regulatório (SDCD/CLP). Os resultados obtidos permitem afirmar que houve significativa redução da variabilidade na granulometria do material após a moagem, redução do consumo de energia e aumento de produção.