bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the aqueous two-phase copolymerization of cationic polyacrylamide
Authors: Wu Yu-min , Liu Yue-tao , Xu Jun , Zhang Na-na
Published: August 2014

Aqueous two-phase copolymerization of acrylamide (AM) and dimethylaminoethyl methacrylate methyl chloride (DMMC) was carried out in polyethylene glycol 20000 (PEG 20000) aqueous solution and with 2,2'-azobis(2- amidinopropane) dihydrochloride (V-50) as the initiator. The effects of the temperature, the PEG 20000 concentration, the DMMC/AM molar ratio and the V- 50 concentration on the initial monomer copolymerization rate (Rp), the total monomers conversion and the molecular weight of copolymers were systematically investigated. The initial copolymerization rate increased with an increase of temperature and V-50 content, contrary to the concentration of the PEG 20000 and DMMC. The molecular weight of the copolymers decreased with increasing the reaction parameters above mentioned. The apparent copolymerization activation energy of the system was calculated to be 65.7 kJ·mol-1 according to Arrhenius equation. The optimal PEG 20000 content of the system was 15%~25% (based on the raw materials). The relationship between the initial copolymerization rate (Rp) and the initiator concentration was discussed, and the kinetics equation was Rp~ [I]0.94.
Weld line behaviour of exfoliated and toughened polypropylene layered silica nanocomposites
Authors: Şen Sinan , Ersoy Osman G. , Nugay Turgut , Nugay Nihan
Published: August 2014

Exfoliated and toughened polypropylene nanocomposites prepared by an introduction of a rubber in the form of compatibilizer toughener: ethylene propylene diene based rubber grafted with maleic anhydride (EPDM-g-MAH) were studied in terms of weld line properties and morphology. Effects of addition of rubber and nanolayer on weld line strength under tensile loading condition of polypropylene matrix were investigated. Data showed that in the absence of either EPDM or nanolayers, a sharp decrease in weld line strength cannot be avoided whereas in the presence of each in optimum ratio, the drastic increase in both toughness and weld line strength values can be easily reached. The beneficial effect is believed to come from the selective placing of nanolayers around the rubber droplets and making them smaller in size which contributes to diffused weld line regions with high mechanical strength.
Novel D-glucose and D-mannose based oligomers: synthesis and characterization
Authors: Pană Ana-Maria , Rusnac Lucian-Mircea , Bandur Geza , Silion Mihaela , Deleanu Călin , Bălan Mihaela
Published: August 2014

This paper presents the synthesis and characterization of two oligomers based on monosaccharides (D-glucose and D-mannose). The oligomers were obtained by the polycondensation of two diacids derived from monosaccharides (3- O-benzyl-5,6-(bis(maleyloxy))-1,2-O-isopropylideneglucofuranose and 1-O-benzyl- 5,6-(bis(maleyloxy))-2,3-O-isopropylidenemannofuranose, respectively), with propane-1,3-diol in the presence of p-toluenesulfonic acid. The oligomers were characterized using FTIR and NMR spectroscopy, HPLC-MS and DSC. The copolymerization of the oligomers with 2-hydroxy-propyl acrylate was studied by DSC to evaluate the possibility of obtaining cross-linked copolymers.
Polystyrene latex particles obtained by emulsifier-free emulsion polymerization and their interaction with bentonite
Authors: Bujanca Ioneta Codrina , Corobea Mihai Cosmin , Miculescu Florin , Dimonie Mihai
Published: August 2014

Polystyrene latex particles were prepared by using an emulsifier-free emulsion polymerization with two ionic initiators: potassium persulfate (KPS) and 2,2’-azobis(2-amidinopropane)dihydrochloride (AIBA). The purpose of this study was to obtain polystyrene latex with a good stability in time, a high surface charge density and a small particle size (between 100 and 1000 nm). We used two distinctive molar concentrations for both initiators: 5.5 mM and 55 mM based on aqueous phase. The analysis showed that in the case of KPS initiator the latexes stability was better. With AIBA as initiator smaller latex particles can be achieved. A high surface charge density was measured for large initiator concentration. We achieved satisfying results with both initiators, the optimal condition of polymerization depending on the subsequent utilization of the latex. The SEM images showed that latexes containing bentonite and latexes with no clay have similar size.
Magnetorheological behaviour of magnetic carrageenan gels against shear and compression strains
Authors: Negami Keisuke , Mitsumata Tetsu
Published: August 2014

Magnetic field effect on the elasticity was investigated for magnetic carrageenan gel when a shear and compressional deformation was applied to the gel. The magnetic carrageenan gel consists of carrageenan of a polysaccharide, and carbonyl iron particles. The dynamic viscoelastic measurement with shear strain revealed that the storage shear modulus of the gel increased from 1.0×104 to 2.3×106 Pa by applying a magnetic field of 320 mT. On the other hand, the compression measurement showed that the Young’s modulus increased from 6.2×104 to 5.9×105 Pa. The relative changes in the modulus with respect to the original modulus were 230 for shear strain and 9.5 for compressional strain, respectively. This strongly indicates that the magnetic field effect on viscoelasticity strongly depends on the geometry of directions of magnetic field and strain. The effect of vibration suppression of the present gel tuned by magnetic field is also presented.
Controlled RAFT synthesis of polystyrene-b-poly(acrylic acid)-b-polystyrene block copolymers and their self-assembly in an ionic liquid [BMIM][PF6]
Authors: Zheng Linping , Chai Yun , Liu Yang , Zhang Puyu
Published: August 2014

The block copolymer of polystyrene-block-polyacrylate-blockpolystyrene (PSt-PAA-PSt) has been synthesized by reversible addition fragmentation chain-transfer (RAFT) polymerization using S,S′-Bis(α,α′-dimethyl-α′′-acetic acid)-trithiocarbonate (BDATC) as chain transfer agent. Three copolymers form micelles in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). The nanostructures of the PSt-PAA-PSt micelles formed in ionic liquid were observed by transmission electron microscopy (TEM). The self-assembled morphologies of the micelles are strongly dependent on the length of PAA block chains when the chain length of PS is fixed. The affinity of PAA chains for water and [BMIM][PF6] reverses with increasing temperature. Research results show that the copolymer with low polydispersity can be obtained by controlling polymerization, and the flexibility of amphiphilic block copolymers for controlling nanostructure in an ionic liquid presents potential applications in many arenas.
A Raman study of nylon 6 annealed under high pressure
Authors: Xu Weijie , Cao Dahu , Yu Qiang
Published: August 2014

Using a cubic-anvil high pressure apparatus, nylon 6 samples were annealed under 400 MPa to 1.5 GPa. The structure changes of nylon 6 are studied by the methods of wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and Raman spectra. Compared with sample prepared at ambient pressure, high pressure treatment makes the hydrogen-bonded sheets pack more closely and thus enhanced CH2 vibration out of the hydrogen-bonded sheets. After high pressure treatment, it is observed that all changes of C-C related vibration modes in nylon 6 are similar with ones in nylon series when the CH2 sequence number increased, from which it is deduced that high pressure treatment reduces the effects of amide group on the chain conformation of nylon 6.
Study on electrical property relaxations of 10 MeV electron beam irradiated HDPE
Authors: Ziaie Farhood , Borhani M. , Majdabadi A. , Kazemi Z.
Published: August 2014

Cross linking of the HDPE was performed with high energy electron beam. EPR spectroscopy was used to study the life time of unpaired electron in the irradiated samples. Dielectric constant and dielectric strength almost remained unchanged but, volume resistively and dissipation factor increased and decreased respectively, after irradiation. The results shows that the dissipation factor is going to be recovered slowly with the storing time at room temperature. It is believed that variation of some electrical properties during time after irradiation are due to the effects of free radical and charge trapping remained in the bulk of material.
Dielectric and thermal properties of thermoplastic elastomer gels in the presence of nanographite
Authors: Paglicawan Marissa A. , Kim Jin Kuk
Published: August 2014

In this work, the effect of different nanographite such as expandable graphite (EG) and exfoliated graphite nanoplatelets (xGnP) on the electrical and thermal properties of nanocomposite thermoplastic elastomer gels prepared from a poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) imbibed with an EBcompatible paraffin oil was investigated. The electrical properties have been studied as a function of variation of nanoparticles in the frequency range of 52 to 107 Hz. For all the nanoparticles studied, the dielectric constant increases as the volume content of the nanoparticles in the TPE gels increases. The increase in dielectric constant was fairly smooth with no clear dielectric singularity in the concentration range studied. However, the percolation threshold in the dielectric spectra was clearly seen. The incorporation of a small quantity of nanographite improved the thermal stability of the swollen midblock of TPEGS, since the particles dispersed in this region, thereby increasing the distinct region of oil degradation temperature but no improvement on SEBS matrix. The results showed that size, shape and agglomeration of the particles with high amount of oil in SEBS system played a role in the dielectric properties and thermal stability.
Synthesis and characterization of functional six-membered ring carbonates for the preparation of orthogonal couplers
Authors: Anders Thorsten , Keul Helmut , Möller Martin
Published: August 2014

On the basis of commercially available trimethylolpropane (TMP) three six-membered ring carbonates were prepared, substituted with reactive side groups: a chloroformate (2a), an imidazolyl carbamate (2b) and a phenyl carbonate (2c). Their synthesis and characterizations are described and compared to known ring carbonates with reactive side groups. Starting from 2a-c orthogonal couplers 3a and 3b were synthesized for conversion under mild reaction conditions. In a model reaction 2-azidoethyl 2-N-acetylamino-2-deoxy- -D-glucopyranose and tertbutyl- N-(3-aminopropyl) carbamate were linked with coupler 3a via a 1,3-dipolar cycloaddition and a nucleophilic ring-opening reaction. This coupling principle can be used for the preparation of multifunctional polymers or surface coatings at ambient conditions.
The role of clay-montmorillonite on thermal characteristics and morphology of electrospun PAN nanofibrous mats
Authors: Zahed Shami , Naser Sharifi-Sanjani
Published: August 2014

Polymer organic-inorganic hybrid nanofibers constitute a new class of materials in which the polymeric nanofibers are reinforced by uniformly dispersed inorganic particles having at least one dimension in nanometer-scale. In the present study, nanofibrous mats of neat and nanocomposite polyacrylonitrile (PAN) were fabricated by electrospinning process. Electrospun PAN and PAN/Na-MMT fibrous mats with the respective mean fiber diameter of about 220 and 160 nm were prepared. The influence of the clay-montmorillonite on the morphology and diameter of nanofibers was investigated by means of scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The microscope techniques results suggested that the PAN/Na-MMT composite nanofibers showed the lower mean fiber diameter than the neat PAN nanofibers. Besides, the difference in nanoclay-content has a slight effect on the distribution of fibers diameter. Thermogravimetric analysis (TGA) results suggested that the introduction of clay-nanomaterials improve the decomposition onset and residual weight percentage of mats at about 31°C and 13 %, respectively. The results of X-ray diffraction (XRD) confirmed that the clay-montmorillonite layers were exfoliated in the polymer matrix. The exfoliation of clay layers was further supported by transition electron microscope (TEM) observations.
Interaction of carbon monoxide with PEDOT-PSS/zeolite composite: effect of Si/Al ratio of ZSM-5 zeolite
Authors: Chanthaanont Pojjawan , Sirivat Anuvat
Published: August 2014

Composites with poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid), PEDOT-PSS, as the matrix containing ZSM-5 zeolites of various Si/Al ratios in the range of 23-280 at 20% (v/v) were fabricated to investigate the effect of Si/Al ratios on electrical conductivity sensitivity responses towards carbon monoxide (CO). The electrical conductivity responses of PEDOTPSS/ ZSM-5 composites were altered due to the available adsorption sites for CO molecules. The electrical conductivity sensitivity to CO increases with decreasing Si/Al ratios. The composites produce irreversible responses when replacing CO with nitrogen. The addition of ZSM-5 zeolites to the pristine PEDOT-PSS improves the electrical conductivity sensitivity of the composites by enhancing the interaction between PEDOT-PSS and CO gas. The composite of ZSM-5 zeolites with a Si/Al ratio equal to 23 gives the highest electrical conductivity sensitivity toward CO.
Synthesis and characterization of amphiphilic graft copolymers with hydrophobic poly(α-methylstyrene) backbone and hydrophilic poly(n-vinylpyrrolidone) side chains
Authors: Sebba Fatima Zohra , Kada Seghier Ould , Benaicha Mohamed , Nemiche Nerjesse
Published: August 2014

In this study, 2-oxopropylmethacrylate-terminated poly(N-vinyl-2- pyrrolidone) is produced by cationic polymerization using HClO4 as an initiator. Termination (end capping) step is accomplished using 2- hydroxypropylmethacrylate (2HPMA) and the polymer product has different chain lengths of molecular weight averages ranging from 672 to 3049 g/mol. The study also synthesised amphipathic graft copolymers having hydrophobic poly(α- methylstyrene) as a backbone chain and hydrophilic poly(N-vinyl-2-pyrrolidone) (PVP) as side chains of various lengths. The copolymer synthesis was accomplished by free radical copolymerization of ω-oxopropylmethacrylate PVP in the presence of α-methyl styrene initiated with benzoyl peroxide. Measurements of the dynamic viscosity of the polymer solution (20% weight of macromonomers in ethanol) show that the viscosity is proportional to the average molecular weights M̅n . However, a reverse behaviour of the viscosity variation with regard to M̅n is observed for graft copolymer samples. The viscosity variation with respect to the graft copolymer mass must be due to steric effects, which are strongly pronounced in grafted copolymer chains. Appearance of the number of side chains attached to poly(α-methylstyrene) backbone reveals that the grafting reaction has occurred with good efficiency.
Rheological properties of pectin, poly(vinyl alcohol) and their blends in aqueous solutions
Authors: Lewandowska Katarzyna , Dąbrowska Aldona , Kaczmarek Halina
Published: August 2014

The new blends composed of natural polysaccharide - pectin and synthetic water soluble polymer - poly(vinyl alcohol) (PVA) are attractive materials due to their biocompatibility, non-toxicity and biodegradability. In this work the rheological properties of aqueous solutions of pectin (PEC), poly(vinyl alcohol) and their mixtures at various weight ratios (70/30, 50/50, 30/70) have been investigated. Flow measurements were carried out using a rotary viscometer with concentric cylinder at different temperatures (20-70 ºC) and shear rates (24- 1234 s-1). The flow parameters and energy of activation have been calculated from the flow curves and Arrhenius plots, respectively. It was found that studied polymer solutions exhibited non-Newtonian behavior, moreover, the flow properties were dependent on the blend composition. The result show that practically there was no thixotropy in studied system but some interactions between PVA and pectin in water occurred.
Comparative study on the effects of galbanic acid, galbanic ferric salt and tetrabromo galbanic acid on photo-oxidative degradation of linear low density (LLDPE) films
Authors: Shahmir Marjan , Asempour Homa
Published: August 2014

Galbanic acid (GA) is known as an effective photo-sensitizing agent in polyethylene. This paper reports the comparative studies on photo-oxidative degradation of LLDPE films in the presence of varying amounts of galbanic ferric salt (Fe-GA), tetrabromo galbanic acid (Br-GA), GA at the optimum concentration of 0.2% (w/w) and the pure polymer film, exposed to Ultra-Vitalux sun lamp. The degradation rate was monitored through the changes in mechanical properties (retained elongation at break and retained tensile strength) and also carbonyl index. The results obtained revealed that Fe-GA efficiency in enhancing oxidation rate of polymer upon UV exposure is remarkably much more than of GA. In contrast, Br-GA is responsible for initiating photo-oxidation of the polymer and has negligible effects on the rate of degradation. Based on the results obtained, it was proposed that the photo-activity of GA in the polymer arises from the C=C bond present in the side group attached to aromatic lacton rings of additive molecule, probably through its reaction with singlet oxygen and subsequent generation of hydroperoxide. This mechanism in combination with catalytic effect of iron (III) accounted for the higher effect of Fe-GA in accelerating photo-oxidation rate of the polymer
Poly(imide-amides) oligomers based on germarylene units containing amino acid moieties: synthesis, characterization and thermal analysis
Authors: Tagle Luis H. , Terraza Claudio A. , Yazigi Nicolás , López Luciano , Ortiz Pablo A. , Leiva Angel
Published: August 2014

Four oligomeric poly(imido-amides) (PIAs) were obtained from dicarboxylic acids, derived from two dianhydrides containing a Ge atom and the amino acids glycine or L-alanine, which reacted with the diamine bis(4- aminophenyl)-diphenylgermane, in order to obtain the PIAs containing two Ge atoms in the main chain. PIAs which contain Me/Me or Ph/Ph on the Ge atom of the dicarboxylic acids moiety, were characterized by IR and 1H and 13C NMR, and elemental analysis. The yields were over 60% with the exception of PIA-II, and the low inh values are indicative of low molecular weight species. Tg and the thermal stability were evaluated by DSC and thermogravimetry respectively. When Lalanine was included in the dicarboxylic acid, it was possible to see lower values of Tg with respect to those with glycine, due to the higher flexibility of the methyl side groups. When phenyl groups are bonded to the Ge atom of the dicarboxylic acid, also there is a decrease of the Tg in front of those with methyl groups, due to that the increase of the volume of the side groups affects negatively the free rotation of the polymeric chain. The TDT values were obtained by dynamic thermogravimetry, and show that these PIAs are not thermally stables materials, because the 10% of weight loss is lower than 400 ºC, with the exception of PIA-IV, in which the value is 403 ºC. The low thermal stability can be due to that the dicarboxylic acids are of aliphatic nature. On the other hand, there was not a clear tendency about the influence of the nature of the amino acid and the groups, methyl or phenyl, bonded to the Ge atom in the dicarboxylic acids.
Physical and mechanical properties of rigid polyurethane foams modified with polystyrene beads
Authors: Malewska Elżbieta , Sabanowska Anna , Polaczek Jerzy , Prociak Aleksander
Published: August 2014

This study presents a method of obtaining porous materials based on the rigid polyurethane foam (RPURF) as the matrix and containing thermoplastic polystyrene beads (EPS) as the fillers. In RPURF-EPS composites, the compact EPS were expanded after heating above a glass transition temperature of the EPS and gas vapouring incorporated inside the EPS, by using heat of exothermic reaction of polyol with isocyanate. The thermal conductivity, compressive strength, core density and cell structure of the new materials were investigated
Powder X-ray diffraction and thermal decomposition correlation studies of nano-crystalline styrene-maleic anhydride graft copolymer-ZnO composites
Authors: Kaur Inderjeet , Singh Bikram , Bhatt Parveen , Bhatt Sarvjeet S.
Published: August 2014

Nano-crystalline (nc) polymer-ZnO composite material has been successfully synthesized by treating styrene-maleic anhydride (SMA) and its graft copolymers with acrylic acid, (AAc), and acrylamide, (AAm), synthesized by chemical method with different wt% ratios of nZnO (40 nm), prepared indigenously in our laboratory, to yield polymer-ZnO nano-composite material. Characterization of SMA, grafted SMA, nc-SMA-ZnO, nc-grafted SMA-ZnO composites was carried out by X-ray diffraction and thermo-gravimetric analysis. Both the studies show an interesting correlation between X-ray and thermal data. XRD pattern of SMA copolymer shows it to be amorphous, while SMA-g-poly(AAc) and SMA-gpoly( AAm) graft copolymers show crystalline orthorhombic structure having (102) orientation with particle size of nano dimensions (44 and 40 nm respectively). Addition of nZnO to nc-SMA-g-poly(AAc) and nc-SMA-g-poly(AAm) shows appreciation in the crystalline behavior with increased intensity of the peaks in the XRD patterns. Thermo-gravimetric analysis (TGA) of SMA shows single stage decomposition with regular loss of weight while nc-SMA-g-poly(AAc) and nc-SMAg- poly(AAm) graft copolymers respectively show an abrupt weight loss up to 25% and 45% at 121.370C and thereafter proceeds with regular decomposition. However, the corresponding composite of SMA with nZnO (10 wt%) shows an abrupt weight loss of 50% similar to grafted SMA while the ZnO embedded composites of AAc and AAm grafted SMA lose 95% of the weight abruptly at the same temperature i.e.121.37 °C. The increased abrupt loss in nZnO- SMA and nZnO-nc-SMA grafted composite is correlated to the increased crystallinity upon addition of nZnO particles to the polymer system. Because of the spontaneous thermal decomposition and release of large amount of heat energy, the newly synthesized nano-composite polymer material can find use as high energy material
Synthesis and solution properties of a meta-linked anionic poly(phenylene ethynylene) conjugated polyelectrolyte
Authors: Liu Kuan , Li Yang , Yang Mujie
Published: August 2014

A meta-linked anionic conjugated polyelectrolyte m-PPYPE-SO3Na was synthesized and characterized by UV-vis, FT-IR, and photoluminescence spectroscopy. It is brown solid readily soluble in water and methanol. The UV-vis absorption spectra of the polymer show strong absorption bands, which correspond to the π-π* transition of π-conjugated segments. Fluorescence spectra in different solvents show that this kind of polymer has solvent-dependency. It was found that the existence of polymer-type surfactant significantly increased the intensity of fluorescence of the polymer. The fluorescence of the polymer in water solution could be effectively quenched by methyl viologen. Linear fit of the quenching plots affords Stern-Volmer constants (Ksv) of 5.65×105M-1 for intrinsic fluorescence emission of the polymer m-PPYPE-SO3Na and this revealed its good fluorescence sensitivity.
Polymers containing phtalimidoalkyl groups in the side chains. effect of the alkyl groups in monolayers at the airwater interface
Authors: Gargallo Ligia , Leiva Angel , González Alvaro , Alegría Luz , Sandoval Claudia , Radic Deodato
Published: August 2014

Surface activity of poly(methacrylate)s containing phthalimidoalkyl groups was studied. Surface pressure-area isotherms ( -A) at the air-water interface were determined. These polymers form stable and condensed monolayers. The monolayers are more condensed and the limiting surface area A0 values decrease when the number of the methylene groups in the lateral chains increases. Surface pressure variation at the semidilute region of the monolayers was expressed in terms of the scaling laws as power function of the surface concentration. The static elasticity εo and the exponent of the excluded volume υ were determined. The hydrophobicity degree of polymers was estimated from the determination of the total surface free energy values by wettability measurements. Molecular dynamic simulation (MDS) was performed in order to explain the experimental behavior of polymers at the air-water interface.
Significantly enhanced dielectric response in composite of P(VDF-TrFE) and modified multi-walled carbon-nanotubes
Authors: Wang Jingwen , Wei Nan , Wang Fang , Wu Congcong , Li Shuqin
Published: August 2014

To develop a high dielectric constant composite of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] and multi-walled carbon-nanotubes (MWCNTs) with desirable homogeneity, MWCNTs were treated with a nitro-sulfuric acid by ultrasonication. Improvement of the dispersibility of chemically modified MWCNTs (a-MWCNTs) in polymer matrix, in comparison with that of unmodified MWCNTs in P(VDF-TrFE), was confirmed by field emission scanning electron microscopy (FESEM)-observed morphologies. Electric behavior of the composites with different volume fraction of dispersed carbon nanotubes phase can be described mainly by percolation theory. The percolation threshold (fc) of composites with a-MWCNTs (fc=0.0308) is larger than that of composites with MWCNTs (fc=0.0216) due to better dispersion of a-MWCNTs in polymer matrix and the reduction of aspect ratio of a-MWCNTs occurred in the modification procedure. The composite with 2.98 vol% (a volume fraction close to the percolation threshold) of a-MWCNTs has a dielectric constant of 592 at 100Hz and room temperature. The composite remains very flexible with an elastic modulus close to that of the parent copolymer.
Aqueous AGET ATRP of sodium 2-acrylamido-2-methyl-N-propane sulfonate yielding strong anionic comb polyelectrolytes
Authors: Tolstov Alexander , Gromadzki Daniel , Netopilík Miloš , Makuška Ričardas
Published: August 2014

Anionic comb polyelectrolytes containing 2-acrylamido-2-methyl-Npropane sulfonate groups both in the mainchain and in the grafts were prepared by activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). The synthetic route included AGET ATRP copolymerization of 2- acrylamido-2-methyl-N-propanesulfonic acid (AMPS) and 2-hydroxyethyl acrylate (HEA) followed by modification of HEA units in the copolymers by 2- bromoisobutyryl bromide yielding macroinitiators which served for “grafting from” AGET ATRP of AMPS. Composition of the final and intermediate products was determined by 1H-NMR spectroscopy, and molecular weight and polydispersity of the resulting polyelectrolytes were estimated by size exclusion chromatography (SEC). Anionic comb polyelectrolytes with relatively low density of the grafts (5 - 7 grafting sites per 100 monomeric units of the mainchain) and relatively short side chains (9 or 25 AMPS units) were synthesized and characterized.
The synthesis and characterization of the polyurethanes with antimicrobial properties
Authors: Borcan Florin , Bolcu Constantin , Filimon Nicoleta , Bandur Geza
Published: August 2014

In this experimental research, thin polyurethane films containing reactive functional groups (hydroxyl and amino groups) were synthesized. The raw materials used in the synthesis are: a hydroxyl component (Elastoflex W5516/115) and an isocyanate component (semiprepolimer type) based on 4,4'- diphenylmethane-diisocyanate (MDI) or toluene-2,4-diisocyanate (TDI). Two different antibiotics were adsorbed on these films: amikacin and ceftazidime which formed physical bonds with the polyurethane matrix. The films were characterized by SEM, DMA and a culture of Escherichia coli and a counting room was used in order to determine the antimicrobial efficiency.
Tobacco use among adolescents in Riyadh Saudi Arabia
Authors: Al-Makadma AbdulKarim S. , Moynihan Melissa , Dobson Sarah , Saewyc Elizabeth
Published: August 2014

Background: Initiation of smoking behavior during adolescence is associated with negative health outcomes. Understanding initiation of smoking behavior in adolescents in relation to other behavioral, health, and environmental factors is essential for effective behavioral modification.

Objective: The aim of this study was to describe tobacco use behaviors among adolescents in Riyadh, Saudi Arabia, and related demographic and social factors.

Subjects: A total of 1430 students aged 14–19 from high schools across the city of Riyadh participated in the study.

Methods: A comprehensive adolescent health survey was administered to students in high school classrooms across Riyadh. Data were analyzed primarily via contingency tables with χ2-tests.

Results: One in five students reported having ever smoked cigarettes, with a significantly higher proportion of boys than girls reporting tobacco use. Students who smoked had significantly lower school connectedness compared with those who never smoked. Tobacco use by family members was common, and students with at least one family member who smoked were significantly more likely to use tobacco themselves.

Conclusion: Improving school connectedness among students by fostering supportive and safe school environments could be a potential strategy for reducing adolescent smoking. Reducing smoking in the general population and educating families about being better role models for youth are also critical.
Growth impairment and growth hormone-IGF-1 axis in infantile anorexia nervosa
Authors: Ghione Silvia , Maestro Sandra , Dati Eleonora , Silvestri Virginia , Baroncelli Giampiero I. , Bertelloni Silvano
Published: August 2014

Infantile anorexia nervosa (AN) is a specific eating disorder of prepubertal children. Poor data are available on growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis in this disorder.

We report on a boy (4.5 years) with progressive growth impairment. At psychiatric assessment (DC: 0-3 R, AXIS I), he fulfilled all required criteria for diagnosis of infantile AN. Endocrine evaluation suggested impaired peripheral response to GH (high GH and low IGF-1 levels), likely related to energy deficiency.

Auxological evaluation was shown as raw data and SDS using Italian reference values. GH secretion was assessed by arginine provocative test; IGFI generation test was done administering recombinant GH (0.05 mg/kg/day for four days). Psychiatric assessment was performed according to the DC:0-3R protocol.

Impaired GH-IGF-1 axis may be involved in growth delay of children with infantile AN. A strict collaboration between endocrine pediatricians and child psychiatrists is advisable in the assessment of poor growing children without recognizable organic causes, showing normal/high GH levels and low IGF-1 values.
Texttheorie und textlinguistische Annotation von Korpora: Bemerkungen zur Rhetorical Structure Theory
Authors: Fritz Gerd
Published: August 2014

The present article contributes to the discussion of methods of corpus studies in the field of text and discourse analysis. Starting with a brief overview of bottom-up and top-down methods of corpus analysis, the article focuses on a critical examination of Rhetorical Structure Theory (RST), a framework for describing natural text that has been widely used for the annotation of texts, especially in the field of computational linguistics. This critical assessment, which is based on an action-theoretic theory of text organization, is, at the same time, used as a means of discussing some quality criteria for textual analysis. After a brief introduction to basic tenets of RST, the article discusses various features of this framework that appear problematic from a theoretical point of view and that tend to cause difficulties for practical analysis. The problems connected to these features include problems of granularity associated with the “classic” set of “rhetorical relations” as well as problems connected to the adjacency and nuclearity conditions. Furthermore it is shown that RST lacks adequate instruments for the description of the topic structure of texts and aspects of linearity and the dynamics of texts, e.g. the discontinuity of functional and thematic elements. The final section of the paper summarizes the results of this critical analysis, briefly reflecting on conceptions of multi-level annotation and suggesting some further steps in the corpus-based analysis of textual organization.
PI3P phosphatase activity is required for autophagosome maturation and autolysosome formation
Authors: Wu Yanwei , Cheng Shiya , Zhao Hongyu , Zou Wei , Yoshina Sawako , Mitani Shohei , Zhang Hong , Wang Xiaochen
Published: August 2014

Autophagosome formation is promoted by the PI3 kinase complex and negatively regulated by myotubularin phosphatases, indicating that regulation of local phosphatidylinositol 3‐phosphate (PtdIns3P) levels is important for this early phase of autophagy. Here, we show that the Caenorhabditis elegans myotubularin phosphatase MTM‐3 catalyzes PtdIns3P turnover late in autophagy. MTM‐3 acts downstream of the ATG‐2/EPG‐6 complex and upstream of EPG‐5 to promote autophagosome maturation into autolysosomes. MTM‐3 is recruited to autophagosomes by PtdIns3P, and loss of MTM‐3 causes increased autophagic association of ATG‐18 in a PtdIns3P‐dependent manner. Our data reveal critical roles of PtdIns3P turnover in autophagosome maturation and/or autolysosome formation.
A Review and Framework for Categorizing Current Research and Development in Health Related Geographical Information Systems (GIS) Studies
Authors: Nøhr C. , Sørensen E. M. , Gudes O. , Geraghty E. M. , Shaw N. T. , Bivona-Tellez C. , Lyseen A. K. ,   the IMIA Health GIS Working Group
Published: August 2014

Objectives: The application of GIS in health science has increased over the last decade and new innovative application areas have emerged. This study reviews the literature and builds a framework to provide a conceptual overview of the domain, and to promote strategic planning for further research of GIS in health.

Method: The framework is based on literature from the library databases Scopus and Web of Science. The articles were identified based on keywords and initially selected for further study based on titles and abstracts. A grounded theory-inspired method was applied to categorize the selected articles in main focus areas. Subsequent frequency analysis was performed on the identified articles in areas of infectious and non-infectious diseases and continent of origin.

Results: A total of 865 articles were included. Four conceptual domains within GIS in health sciences comprise the framework: spatial analysis of disease, spatial analysis of health service planning, public health, health technologies and tools. Frequency analysis by disease status and location show that malaria and schistosomiasis are the most commonly analyzed infectious diseases where cancer and asthma are the most frequently analyzed non-infectious diseases. Across categories, articles from North America predominate, and in the category of spatial analysis of diseases an equal number of studies concern Asia.

Conclusion: Spatial analysis of diseases and health service planning are well-established research areas. The development of future technologies and new application areas for GIS and data-gathering technologies such as GPS, smartphones, remote sensing etc. will be nudging the research in GIS and health.
Big Data, Smart Homes and Ambient Assisted Living
Authors: Wass S. , Vimarlund V.
Published: August 2014

Objectives: To discuss how current research in the area of smart homes and ambient assisted living will be influenced by the use of big data.

Methods: A scoping review of literature published in scientific journals and conference proceedings was performed, focusing on smart homes, ambient assisted living and big data over the years 2011-2014.

Results: The health and social care market has lagged behind other markets when it comes to the introduction of innovative IT solutions and the market faces a number of challenges as the use of big data will increase. First, there is a need for a sustainable and trustful information chain where the needed information can be transferred from all producers to all consumers in a structured way. Second, there is a need for big data strategies and policies to manage the new situation where information is handled and transferred independently of the place of the expertise. Finally, there is a possibility to develop new and innovative business models for a market that supports cloud computing, social media, crowdsourcing etc.

Conclusions: The interdisciplinary area of big data, smart homes and ambient assisted living is no longer only of interest for IT developers, it is also of interest for decision makers as customers make more informed choices among today’s services. In the future it will be of importance to make information usable for managers and improve decision making, tailor smart home services based on big data, develop new business models, increase competition and identify policies to ensure privacy, security and liability.
Big Data in Healthcare – Defining the Digital Persona through User Contexts from the Micro to the Macro
Authors: Monkman H. , Petersen C. , Weber J. , Borycki E. M. , Adams S. , Collins S. , Kuziemsky C. E.
Published: August 2014

Objectives: While big data offers enormous potential for improving healthcare delivery, many of the existing claims concerning big data in healthcare are based on anecdotal reports and theoretical vision papers, rather than scientific evidence based on empirical research. Historically, the implementation of health information technology has resulted in unintended consequences at the individual, organizational and social levels, but these unintended consequences of collecting data have remained unaddressed in the literature on big data. The objective of this paper is to provide insights into big data from the perspective of people, social and organizational considerations.

Method: We draw upon the concept of persona to define the digital persona as the intersection of data, tasks and context for different user groups. We then describe how the digital persona can serve as a framework to understanding sociotechnical considerations of big data implementation. We then discuss the digital persona in the context of micro, meso and macro user groups across the 3 Vs of big data.

Results: We provide insights into the potential benefits and challenges of applying big data approaches to healthcare as well as how to position these approaches to achieve health system objectives such as patient safety or patient-engaged care delivery. We also provide a framework for defining the digital persona at a micro, meso and macro level to help understand the user contexts of big data solutions.

Conclusion: While big data provides great potential for improving healthcare delivery, it is essential that we consider the individual, social and organizational contexts of data use when implementing big data solutions.
Prediction of the overflow of sediment from trailer dredgers
Authors: Spearman Jeremy
Published: August 2014

This paper describes a model of the sediment transport processes inside the hopper of a trailer suction hopper dredger. The model is part of the TASS system – a software program that enables the user to predict the spatial development and concentration of turbidity plumes arising from dredging activities by trailer suction hopper dredgers. TASS has been developed because of a recognised need by the dredging industry to improve the quality of predictions of the effects of dredging in environmental impact assessments. This paper describes the hopper process model and the validation of overflow predictions against validation measurements off the Dutch, German and Australian coasts. The model is shown to perform well in quantitative comparisons with data for dredging silt and sand in the Netherlands and Germany. A more qualitative comparison in Australia (owing to uncertainty in the nature of the soil being dredged) also indicates the hopper process model predicts the correct range of sediment discharge.
Quasi-online flood forecasting downstream of dams based on rainfall thresholds
Authors: Saghafian Bahram , Golian Saeed , Khodadadi Hossein
Published: August 2014

Dams are built to supply water to users and often to protect people and properties against floods in downstream areas. Efficiency of dams for flood control is improved substantially if a flood forecasting system is implemented. Rainfall threshold (RT) depths correspond to the occurrence of critical discharge at given cross-sections for given rainfall durations and initial soil moisture conditions of the upstream watershed. Here, we present an RT-based approach for offline flood forecasting downstream of dams. The proposed methodology incorporates rainfall-runoff and reservoir routing models while the spatial distribution of rainfall is probabilistically modeled based on a Monte Carlo approach. The RT curves are derived as a function of initial water elevation in the reservoir. The algorithm is implemented for a flood-prone area downstream of a dam in southwestern Iran. The results showed a clear rise in the RT values compared to the no-dam case, which is mainly due to the reservoir routing effect. The rate of rise in the RT values decreased with higher initial water elevation in the reservoir. The proposed method also provides the operator with the flexibility of adopting one of the various RT curves subject to different probabilities based on risk tolerance.
Evaluation of the climate generator model CLIGEN for rainfall data simulation in Bautzen catchment area, Germany
Authors: Al-Mukhtar Mustafa , Dunger Volkmar , Merkel Broder
Published: August 2014

The objectives of this study were to: (i) evaluate the CLImate GENerator model (CLIGEN v.5.22564) to reproduce daily, monthly and yearly precipitation values across Bautzen catchment area, as well as storm patterns including maximum monthly 30 min intensity and average monthly storm duration at two stations, (ii) cross-validate CLIGEN's spatial and temporal prediction ability. Daily rainfall data were collected from three stations (Kubschütz, Sohland and Spittwitz) for the period 1991–2010, in addition to breakpoint rainfall data from Kubschütz for the period 2004–2010 and Sohland for the period 2005–2010. The daily data from the three stations were interpolated to the entire catchment area. These interpolated observed data were used to validate the results from CLIGEN twice, once when the model was run with input parameters calculated from the interpolated data, and once when the model was run with input parameters calculated from each station independently. The model was cross-validated with respect to time at each station independently. For that purpose, the period 1991–2010 was subdivided into two intervals for each station; the first one was used to calibrate the model and the second one to validate it and vice versa. Results showed that CLIGEN can be sufficiently used to simulate rainfall and storm pattern parameters.
Similarity-based error prediction approach for real-time inflow forecasting
Authors: Akbari Mahmood , Afshar Abbas
Published: August 2014

Regardless of extensive researches on hydrologic forecasting models, the issue of updating the outputs from forecasting models has remained a main challenge. Most of the existing output updating methods are mainly based on the presence of persistence in the errors. This paper presents an alternative approach to updating the outputs from forecasting models in order to produce more accurate forecast results. The approach uses the concept of the similarity in errors for error prediction. The K nearest neighbor (KNN) algorithm is employed as a similarity-based error prediction model and improvements are made by new data, and two other forms of the KNN are developed in this study. The KNN models are applied for the error prediction of flow forecasting models in two catchments and the updated flows are compared to those of persistence-based methods such as autoregressive (AR) and artificial neural network (ANN) models. The results show that the similarity-based error prediction models can be recognized as an efficient alternative for real-time inflow forecasting, especially where the persistence in the error series of flow forecasting model is relatively low.
Performance of a permeable reactive barrier for in situ removal of ammonium in groundwater
Authors: Hou Guohua , Liu Fei , Liu Mingzhu , Kong Xiangke , Li Shengpin , Chen Liang , Colberg Patricia J. S. , Jin Song , Chen Honghan
Published: August 2014

Nitrogen as ammonium (NH4+-N) is one of the most common nitrogen contaminants in groundwater; this is particularly true in the industrial and agricultural regions of northern China, where rapid population growth and economic development have stressed public water supplies and reduced groundwater quality. In this study, we report the performance of a zeolite permeable reactive barrier (PRB) designed to remove ammonium from contaminated river water that infiltrates to a groundwater aquifer that serves as a drinking water supply for the city of Shenyang. Groundwater monitoring data obtained over 5 months of operation indicate that ammonium concentrations in the groundwater decreased from 2–10 mg/L to <0.5 mg/L after the PRB was installed in the vicinity. Data suggest that ammonium removal was mainly due to sorption and ion exchange, with NH4+ exchanged with Na+ and K+ in the zeolite. After more than 1 year of continuous operation, there is no evidence of microbial ammonium oxidation. To our knowledge, this was the first field-scale demonstration of a PRB in China.
Energy efficiency in water distribution systems – a path to an ideal network: AGS experience
Authors: Feliciano J. , Almeida R. , Santos A. , Ganhão A. , Covas D. , Alegre H.
Published: August 2014

Infrastructure asset management (IAM) gave a step forward in Portuguese water utilities due to recent legal obligations in developing IAM plans. An effort was made by AGS (Administração e Gestão de Sistemas de Salubridade, S.A.), private operator in 17 water utilities, to achieve a higher level of managing data. Data management was an important hurdle to be overcome in order to accurately assess performance indicators. An appropriate bridge to be made is the link between IAM methodological processes and current operational management; this link is crucial when alternative solutions are defined in the planning stage and decisions need to be made. In the past, through continuously hydraulic modelling collaborative projects, AGS achieved sufficient maturity in several processes, such as (a) update network maps, (b) link geographical information system with other information systems, and (c) profiling consumption demand. Nowadays, concerns related with energy savings are gaining importance; concepts as energy efficiency, reducing carbon footprint and gas emissions should be followed. This paper describes an approach to energy assessment in a real water distribution system, where performance indicators associated with energy efficiency were computed for three different operational alternatives. Results considering a balance between cost and performance dimensions were assessed.