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Sample records for atrp macroinitiator approach

  1. Fluorinated bio-acceptable polymers via an ATRP macroinitiator approach

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie; Haddletion, D.M.; Hvilsted, Søren

    2007-01-01

    Polymers derived from bio-acceptable poly(methyl methacrylate) (PMMA), poly(2-methoxyethyl acrylate) (PMEA), and poly(oligo(ethylene glycol) methyl ether methacrylate) (PPEGMA) have been prepared via atom transfer radical polymerization (ATRP) utilizing an initiator prepared from a fluoroalkoxy......-methanimine with the methacrylates MMA and PEGMA and 1,1,4,7,10,10-hexamethyltriethylene tetramine (HMTETA) with MEA. In all cases the use of the fluorinated initiator results in a lower apparent rate of propagation (k(p)(aPP)) as compared with the more conventional and nonfluorinated initiator, ethyl 2-bromoisobutyrate...

  2. Synthesis by ATRP of triblock copolymers with densely grafted styrenic end blocks from a polyisobutylene macroinitiator

    DEFF Research Database (Denmark)

    Truelsen, Jens Høg; Kops, Jørgen; Pedersen, Walther Batsberg

    2000-01-01

    A macroinitiator was prepared from a triblock copolymer of polyisobutylene (PIB) with end blocks of poly(p-methylstyrene) (P(p-MeS)) by bromination to obtain initiating bromomethyl groups for atom transfer radical polymerization (ATRP). Controlled polymerization of styrene and p-acetoxystyrene yi......A macroinitiator was prepared from a triblock copolymer of polyisobutylene (PIB) with end blocks of poly(p-methylstyrene) (P(p-MeS)) by bromination to obtain initiating bromomethyl groups for atom transfer radical polymerization (ATRP). Controlled polymerization of styrene and p...

  3. Synthesis of α-Bromine- Terminated Polystyrene Macroinitiator and Its Initiation of MMA Polymerization by ATRP

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the present paper the synthesis of block copolymers via the transformation from living anionic polymerization (LAP) to atom transfer radical polymerization (ATRP) was described. Α-Bromine-terminated polystyrenes(PStBr) in the LAP step was prepared by using n-BuLi as initiator, tetrahydrofuran (THF) as the activator, α-methylstyrene (α-MeSt) as the capping group and liquid bromine (Br2) as the bromating agent. The effects of reaction conditions such as the amounts of α-MeSt, THF, and Br2 as well as molecular weight of polystyrene on the bromating efficiency (BE) and coupling extent (CE) were examined. The present results show that the yield of PStBr obtained was more than 93.8% and the coupling reaction was substantially absent. PStBr was further used as the macroinitiator in the polymerization of methyl-methacrylate(MMA) in the presence of copper(Ⅰ) halogen and 2,2-bipyridine(bpy) complexes. It was found that the molecular weight of the resulted PSt-b-PMMA increased linearly with the increase of the conversion of MMA and the polydispersity was 1.2-1.6. The structures of PStBr and P(St-b-MMA) were characterized by 1H NMR spectra.

  4. Preparation of well-defined polystyrene/silica hybrid nanoparticles by ATRP

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Immobilization of the atom transfer radical polymerization(ATRP)macroinitiators at the silica nanoparticle surfaces was achieved through surface modification with excess toluene-2,4-diisocynate(TDI),after which the residual isocyanate groups were converted into ATRP macroinitiators.Structurally well-defined polystyrene chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined,densely grafted outer polystyrene by ATRP,which was initiated by the as-synthesized silica-based macroinitiator.FTIR,NMR and gel permeation chromatography(GPC)were used to characterize the polystyrene/silica hybrid particles.

  5. Preparation of well-defined polystyrene/silica hybrid nanoparticles by ATRP

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Immobilization of the atom transfer radical polymerization (ATRP) macroinitiators at the silica nanoparticle surfaces was achieved through surface modification with excess toluene-2,4-diisocynate (TDI), after which the residual isocyanate groups were converted into ATRP macroinitiators. Structurally well-defined polystyrene chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined, densely grafted outer polystyrene by ATRP, which was initiated by the as-synthesized silica-based macroinitiator. FTIR, NMR and gel permeation chro-matography (GPC) were used to characterize the polystyrene/silica hybrid particles.

  6. Kinetic Studies of Atom Transfer Radical Polymerisations of Styrene and Chloromethylstyrene with Poly(3-hexyl thiophene Macroinitiator

    Directory of Open Access Journals (Sweden)

    Nattawoot Rattanathamwat

    2015-01-01

    Full Text Available Poly(3-hexyl thiophene-b-poly(styrene-co-chloromethylstyrene copolymers, to be used as a prepolymer for preparing donor-acceptor block copolymers for organic solar cells, have been synthesised by reacting P3HT macroinitiators with styrene and chloromethylstyrene via three types of atom transfer radical polymerisation (ATRP systems, which are (1 a normal ATRP, (2 activators generated by electron transfer (AGET, and (3 a simultaneous reverse and normal initiation (SR&NI. The kinetics of these ATRP systems were studied as a function of monomers to the macroinitiator molar ratio. It was found that all of the three types of ATRP systems led to first order kinetics with respect to monomers. The highest rate constant (k of 3.4 × 10−3 s−1 was obtained from the SR&NI ATRP system. The molecular weights of the product determined by the GPC were lower than were the theoretical values. The result was discussed in light of the chain transfer reaction to the poly(chloromethylstyrene repeating units. Morphology of the synthesized block copolymers, examined by an atomic force microscopy (AFM, were also compared and discussed.

  7. Synthesis of novel glycopolymer brushes via a combination of RAFT-mediated polymerisation and ATRP

    Directory of Open Access Journals (Sweden)

    Eric T.A. van den Dungen

    2011-03-01

    Full Text Available Glycopolymers (synthetic sugar-containing polymers have become increasingly attractive to polymer chemists because of their role as biomimetic analogues and their potential for commercial applications. Glycopolymers of different structures confer high hydrophilicity and water solubility and can therefore be used for specialised applications, such as artificial materials for a number of biological, pharmaceutical and biomedical uses. The synthesis and characterisation of a series of novel glycopolymer brushes, namely poly(2-(2-bromoisobutyryloxy ethyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside (P(BIEM-g-P(6-O-MMAGIc, poly(2-(2-bromoisobutyryloxy ethyl methacrylate-co-methyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside P(BIEM-co-MMA-g-P(6-O-MMAGIc, poly(2-(2-bromoisobutyryloxy ethyl methacrylate-b-methyl methacrylate-g-poly(methyl 6-O-methacryloyl-α-D-glucoside P(BIEM-b-MMA-g-P(6-O-MMAGIc and poly(4-vinylbenzyl chloride-alt-maleic anhydride-g-poly(methyl 6-O-methacryloyl-α-D-glucoside (P(Sd-alt-MAnh-g-P(6-O-MMAGIc are described in this paper. Reversible addition-fragmentation chain transfer (RAFT-mediated polymerisation was used to synthesise four well-defined atom transfer radical polymerisation (ATRP macroinitiators (the backbone of the glycopolymer brushes. These ATRP macroinitiators were subsequently used in the ‘grafting from’ approach (in which side chains are grown from the backbone to prepare high molar mass and low polydispersity index glycopolymer brushes with different grafting densities along the backbone. The number average molar mass of the glycopolymer brushes was determined using size exclusion chromatography with a multi-angle laser light

  8. Synthesis and characterization of a novel water-soluble cationic diblock copolymer with star conformation by ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuzhao [Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 (Canada); School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Xiao, Miaomiao [Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 (Canada); Zheng, Anna [School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Xiao, Huining, E-mail: hxiao@unb.ca [Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3 (Canada)

    2014-10-01

    A water-soluble cationic diblock copolymer, CD-PAM-b-PMeDMA, was synthesized through atom transfer radical polymerization (ATRP) from a β-cyclodextrin (CD) macroinitiator with 10-active sites (10Br-β-CD). In order to reduce the cytotoxicity of the CD-PAM-b-PMeDMA, biocompatible polyacrylamide (PAM) was first introduced onto the surface of β-CD as a scaffold structure by ATRP using the 10Br-β-CD as a macroinitiator. The reaction conditions of AM were explored and optimized. The ATRP of [2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (MeDMA) was also performed to synthesize the second cationic block using the resulting CD-PAM as a macroinitiator. The resulting diblock copolymer shows an increased hydrodynamic radius in aqueous solution with a pretty low concentration compared with β-CD. In addition, it appears a near-uniform coniform after being deposited on mica ascribed to the presence of an asymmetric 10-arm structure. - Highlights: • A 10-arm diblock polymer was prepared by ATRP for the potential use as a non-viral gene delivery. • PAM was first synthesized in a controlled manner considering its biocompatibility. • The hydrodynamic radius of the copolymer in aqueous solution increase to 130 nm from 7.5 nm of CD. • The copolymer appears coniform after deposited on mica surface due to the charge attraction.

  9. SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)

    Institute of Scientific and Technical Information of China (English)

    Bing Liu; Feng Liu; Ning Luo; Sheng-kang Ying; Qing Liu

    2000-01-01

    Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in the polymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared by the integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum, respectively. A new way to design block copolymers (the combination of LAP and ATRP) was developed.

  10. Surface Initiated Polymerizations via e-ATRP in Pure Water

    NARCIS (Netherlands)

    Hosseiny, Seyed Schwan; van Rijn, Patrick

    2013-01-01

    Here we describe the combined process of surface modification with electrochemical atom transfer radical polymerization (e-ATRP) initiated from the surface of a modified gold-electrode in a pure aqueous solution without any additional supporting electrolyte. This approach allows for a very controlle

  11. Cationic quaternization of cellulose with methacryloyloxy ethyl trimethyl ammonium chloride via ATRP method

    Energy Technology Data Exchange (ETDEWEB)

    Supeno [Cenderawasih University, Jayapura, Papua, Indonesia and School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Daik, Rusli, E-mail: rusli@ukm.edu.my [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); El-Sheikh, Said M. [Nano-Structured Materials Division, Advanced Materials Department, Central Metallurgical Research and Development Institute, Cairo (Egypt)

    2014-09-03

    The synthesis of a cationic cellulose copolymer from cellulose macro-initiator (MCC-BiB) and quaternary compound monomer (METMA) via atom transfer radical polymerization (ATRP) was studied. By using dimethylformamide (DMF), the optimum condition for successful synthesis was at the mole ratio of MCC-BIB:Catalyst:METMA = 1:1:26. The highest copolymer recovery was 93.2 % for 6 h and at 40°C. The copolymer was insoluble in weak polar solvents such as THF and DMF but soluble in methanol and water. The chemistry of cellulose copolymer was confirmed by the FTIR and TGA in which the METMA monomer was used as a reference. The absence of CC bond in the CiB-g-METMA spectrum indicated that graft copolymerization occurred.

  12. Block and Hetero Ethyl Cellulose Graft Copolymers Synthe- sized via Sequent and One-pot ATRP and "Click" Reactions%Block and Hetero Ethyl Cellulose Graft Copolymers Synthe- sized via Sequent and One-pot ATRP and "Click" Reactions

    Institute of Scientific and Technical Information of China (English)

    李琴梅; 康宏亮; 刘瑞刚; 黄勇

    2012-01-01

    Ethyl cellulose graft copolymers with block and hetero side chains, ethyl cellulose graft [polystyrene-b-poly- (ethylene glycol)] [EC-g-(PS-b-PEG)] and ethyl cellulose graft polystyrene and polyethylene glycol [EC-g-(PS-PEG )] were synthesized by atomic transfer radical polymerization (ATRP) and alkyne-azide "click" reactions and "one-pot" ATRP and "click" reactions, respectively. For the synthesis of EC-g-(PS-b-PEG), the macroinitiator for ATRP was first synthesized via the esterification of hydroxyl groups of EC with 2-bromoisobutyryl bromide to re- sult ethyl cellulose 2-bromoisobutyryl ester (EC-Br). The degree of substitution of bromide groups, which deter- mined the graft density, can be tailored by varying the feeding ratios of the hydroxyl groups to 2-bromoisobutyryl bromide. Then ATRP was carried out for preparing EC-g-PS-Br with well-defined length of PS chains. The EC-g-PS-Br copolymers were then converted to EC-g-PS-N3 and then reacted with end alkyne-functionalized PEG via click to result in EC-g-(PS-b-PEG). The EC-g-(PS-PEG) copolymers were synthesized by converting bromide groups of EC-Br to azide groups (EC-Br-N3) and then by one-pot ATRP and "click" reactions. The resultant graft copolymers were characterized by FTIR and IH NMR. The results indicate the success of the synthetic procedure of the cellulose grail copolymers with block and hetero side chains.

  13. Surface Initiated Polymerizations via e-ATRP in Pure Water

    Directory of Open Access Journals (Sweden)

    Seyed Schwan Hosseiny

    2013-10-01

    Full Text Available Here we describe the combined process of surface modification with electrochemical atom transfer radical polymerization (e-ATRP initiated from the surface of a modified gold-electrode in a pure aqueous solution without any additional supporting electrolyte. This approach allows for a very controlled growth of the polymer chains leading towards a steady increase in film thickness. Electrochemical quartz crystal microbalance displayed a highly regular increase in surface confined mass only after the addition of the pre-copper catalyst which is reduced in situ and transformed into the catalyst. Even after isolation and washing of the modified electrode surface, reinitiation was achieved with retention of the controlled electrochemical ATRP reaction. This reinitiation after isolation proves the livingness of the polymerization. This approach has interesting potential for smart thin film materials and offers also the possibility of post-modification via additional electrochemical induced reactions.

  14. Synthesis of PMMA-b-PU-b-PMMA tri-block copolymers through ARGET ATRP in the presence of air

    Directory of Open Access Journals (Sweden)

    P. Krol

    2013-03-01

    Full Text Available ARGET (activators regenerated by electron transfer ATRP (atom transfer radical polymerization has been successfully performed (in flasks fitted with rubber septa without the need for use of Schlenk line in the presence of limited amount of air and with a very small (370 ppm amount of copper catalyst together with an appropriate reducing agent Cu(0. Novelty of this work is that the poly(methyl methacrylate-block-polyurethane-block-poly(methyl methacrylate triblock copolymers were synthesized for the first time through ARGET ATRP, by using tertiary bromine-terminated polyurethane as a macroinitiator (MBP-PU-MBP, CuBr2 or CuCl2 as a catalyst and N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA or 2,2'-bipyridine (Bpy as a complexing agent. As the polymerization time increases, both the monomer conversion and ln([M]0/[M] increased and the molecular weight of copolymer increases linearly with increasing conversion. Theoretical number-average molecular weight (Mn, th of the tri-block copolymers was found to be comparable with number-average molecular weight determined by GPC analyses (Mn, GPC. These results indicate that the formation of the tri-block copolymers was through atom transfer radical polymerization mechanism. 1H and 13C NMR spectral methods were employed to confirm chemical structures of synthesized macroinitiator and tri-block copolymers. Mole percentage of PMMA in the tri-block copolymers was calculated using 1H NMR spectroscopy and was found to be comparable with the GPC results. Additionally, the studies of surface properties (confocal microscopy and SFE of tri-block copolymer coatings confirmed the presence of MMA segments.

  15. Synthesis of Graft Copolymer of Natural Rubber by ATRP Ⅲ.Preparation of NR-g-PMMA%采用ATRP合成天然橡胶接枝共聚物——Ⅲ.NR-g-PMMA的制备

    Institute of Scientific and Technical Information of China (English)

    赵伟; 廖建和; 廖禄生; 杨耀华; 黄仙红; 陈永平

    2012-01-01

    An atom transfer radical polymerization(ATRP) macroinitiator, bromo-(natural rubber) [NR-Br(l) ], was synthesized by the reaction of natural rubber (NR) with N-bromosuccinimide. A novel graft copolymer, (natural rubber)-g-poly( methyl methacrylate) [NR-g-PMMA(2) ] , was prepared from methyl methacrylate (MMA) using 1 as a macroinitiator and CuBr/PMDTA as the catalyst by ATRP. The structures were characterized by !H NMR and IR. The results of preliminary study of graft copolymerization dynamics showed that the reaction of NR with NBS at high temperature easily occurred addition and cyclization, 1 prepared at room temperature exhibited higher initiating activity, and the graft copolymerization accorded with first-order kinetic reaction because the molecular weight of 2 increaseed as MMA monomer conversion increases.%N-溴代丁二酰亚胺与天然橡胶(NR)反应合成了大分子引发剂——溴代天然橡胶[NR-Br(1)].通过原子转移自由基聚合(ATRP),以CuBr/PMDTA为催化体系,1引发甲基丙烯酸甲酯(MMA)接枝共聚制得新型天然橡胶-g-聚甲基丙烯酸甲酯[NR-g-PMMA(2)],其结构经1H NMR和IR表征.初步聚合反应动力学研究结果表明,NBS与NR在高温下反应容易伴随双键加成和环化反应,于室温反应所得1具有较高的引发活性;接枝聚合符合一级动力学反应,即2的分子量随MMA单体转化率的提高而增加.

  16. How are radicals (re)generated in photochemical ATRP?

    Science.gov (United States)

    Ribelli, Thomas G; Konkolewicz, Dominik; Bernhard, Stefan; Matyjaszewski, Krzysztof

    2014-09-24

    The polymerization mechanism of photochemically mediated Cu-based atom-transfer radical polymerization (ATRP) was investigated using both experimental and kinetic modeling techniques. There are several distinct pathways that can lead to photochemical (re)generation of Cu(I) activator species or formation of radicals. These (re)generation pathways include direct photochemical reduction of the Cu(II) complexes by excess free amine moieties and unimolecular reduction of the Cu(II) complex, similar to activators regenerated by electron-transfer (ARGET) ATRP processes. Another pathway is photochemical radical generation either directly from the alkyl halide, ligand, or via interaction of ligand with either monomer or with alkyl halides. These photochemical radical generation processes are similar to initiators for continuous activator regeneration (ICAR) ATRP processes. A series of model experiments, ATRP reactions, and kinetic simulations were performed to evaluate the contribution of these reactions to the photochemical ATRP process. The results of these studies indicate that the dominant radical (re)generation reaction is the photochemical reduction of Cu(II) complexes by free amines moieties (from amine containing ligands). The unimolecular reduction of the Cu(II) deactivator complex is not significant, however, there is some contribution from ICAR ATRP reactions involving the interaction of alkyl halides and ligand, ligand with monomer, and the photochemical cleavage of the alkyl halide. Therefore, the mechanism of photochemically mediated ATRP is consistent with a photochemical ARGET ATRP reaction dominating the radical (re)generation.

  17. Synthesis of multi-functional nanocapsules via interfacial AGET ATRP in miniemulsion for tumor micro-environment responsive drug delivery.

    Science.gov (United States)

    Tian, Kun; Zeng, Jin; Zhao, Xubo; Liu, Lei; Jia, Xu; Liu, Peng

    2015-10-01

    Novel multi-functional polymeric hollow nanocapsules (PHN) based on the crosslinked poly(tert-butyl acrylate) (PtBA) shells were synthesized in a miniemulsion interfacial polymerization via activator generated electron transfer atom transfer radical polymerization (AGET ATRP) technique with N,N'-bis(acryloyl) cystamine (BACy) as cross-linking agent, CuBr₂ as catalyst, ascorbic acid (VC) as reducing agent and hexadecane as inert solvent. In the AGET ATRP, a folate-conjugated block copolymer, folate-poly(ethylene glycol)-b-poly(tert-butyl acrylate) (FA-PEG-tBA-Br), was used as macroinitiator/stabilizer, and the specific amphiphilic nature of the copolymer led the extending inward of polymer chains. The DLS analysis directly showed the PHN with an average diameter of 150 nm was obtained. After the PtBA shells were transformed into poly(acrylic acid) (PAA) by hydrolysis, doxorubicin (DOX), as a model drug, was loaded efficiently into the hydrolyzed polymeric hollow nanocapsules (HPHN), then the in vitro release of drug was carried out in phosphate buffer solution (PBS, pH 7.4 or 5.0, with or without DTT or GSH of different concentrations). It showed that the existence of folate group significantly improved pH stimuli-responsive and DOX-loading capacity of the polymeric nanocapsules. An acidic pH (5.0) and presence of GSH would accelerate the DOX release behavior. Thus, these multi-functional polymeric nanocapsules have excellent available properties in the field of targeted and controlled drug delivery for cancer therapy.

  18. Dendritic Macroinitiator for the Ring-Opening Polymerization of γ-Benzyl L-Glutamate N-Carboxyanhydride

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By using OH-terminated polyarylether dendrimer and N-Fmoc-glycine as raw materials, the dendritic polyarylether 2-aminoacetate (G3-NH2) was synthesized via two step reactions. G3-NH2 as a macroinitiator for the ring-opening polymerization of γ-benzyl L-glutamate N-carboxyanhydride was investigated. It is found that the resulting copolymers possessed relatively high molecular weight and narrow molecular weight distribution (1.12< Mw/Mn<1.28).

  19. Rational tailoring of substrate and inhibitor affinity via ATRP polymer-based protein engineering.

    Science.gov (United States)

    Murata, Hironobu; Cummings, Chad S; Koepsel, Richard R; Russell, Alan J

    2014-07-14

    Atom transfer radical polymerization (ATRP)-based protein engineering of chymotrypsin with a cationic polymer was used to tune the substrate specificity and inhibitor binding. Poly(quaternary ammonium) was grown from the surface of the enzyme using ATRP after covalent attachment of a protein reactive, water-soluble ATRP-initiator. This "grafting from" conjugation approach generated a high density of cationic ammonium ions around the biocatalytic core. Modification increased the surface area of the protein over 40-fold, and the density of modification on the protein surface was approximately one chain per 4 nm(2). After modification, bioactivity was increased at low pH relative to the activity of the native enzyme. In addition, the affinity of the enzyme for a peptide substrate was increased over a wide pH range. The massively cationic chymotrypsin, which included up to 2000 additional positive charges per molecule of enzyme, was also more stable at extremes of temperature and pH. Most interestingly, we were able to rationally control the binding of two oppositely charged polypeptide protease inhibitors, aprotinin and the Bowman-Birk trypsin-chymotrypsin inhibitor from Glycine max, to the cationic derivative of chymotrypsin. This study expands upon our efforts to use polymer-based protein engineering to predictably engineer enzyme properties without the need for molecular biology.

  20. Utilizing ATRP to Design Self-Regenerating Polymer Gels

    Science.gov (United States)

    Yong, Xin; Averick, Saadyah; Kuksenok, Olga; Matyjaszewski, Krzysztof; Balazs, Anna

    2014-03-01

    Using newly developed computational approaches, we design a gel system capable of re-growth after a substantial section of the material was cut away. Atom transfer radical polymerization (ATRP) is utilized to form gels with preserved ``living'' chain ends and residual unreacted cross-linking groups. When this ``living'' gel is cut, these active species are exposed to a solution containing monomer, crosslinker, initiator and catalyst. A ``repairing'' polymerization occurs from both the new initiators introduced in the outer solution and the reactive chain ends present at the cut site. This new polymerization results in a covalent linkage between the initial living gel and the new gel prepared in the outer solution, and the connection is promoted by the presence of residual cross-linking groups. By measuring the diffusion of the outer solution into the cut gel and characterizing the width and strength of the interface between the initial and new gels, we identify the optimum parameters that yield a strong interface between the gel layers. Our simulations results are in good agreement with our experimental studies. This strategy not only regenerates ``injured'' gels, but also offers a novel means to engineer multi-layered composite gels.

  1. Functional lignocellulosic materials prepared by ATRP from a wood scaffold

    Science.gov (United States)

    Cabane, Etienne; Keplinger, Tobias; Künniger, Tina; Merk, Vivian; Burgert, Ingo

    2016-01-01

    Wood, a natural and abundant source of organic polymers, has been used as a scaffold to develop novel wood-polymer hybrid materials. Through a two-step surface-initiated Atom Transfer Radical Polymerization (ATRP), the porous wood structure can be effectively modified with polymer chains of various nature. In the present study, polystyrene and poly(N-isopropylacrylamide) were used. As shown with various characterization techniques including confocal Raman microscopy, FTIR, and SEM/EDX, the native wood ultrastructure and features are retained and the polymer chains can be introduced deep within the wood, i.e. inside the wood cell walls. The physical properties of the new materials have been studied, and results indicate that the insertion of polymer chains inside the wood cell wall alters the intrinsic properties of wood to yield a hybrid composite material with new functionalities. This approach to the functionalization of wood could lead to the fabrication of a new class of interesting functional materials and promote innovative utilizations of the renewable resource wood. PMID:27506369

  2. Polymers and block copolymers of fluorostyrenes by ATRP

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Borkar, Sachin; Abildgaard, Lillian;

    2002-01-01

    Fully or partly fluorinated polymers have many desirable and intriguing properties. In the framework of a larger program on design and control of new functional block copolymers we recently employed the Atom Transfer Radical Polymerization (ATRP) protocol on 2,3,4,5,6-pentafluorostyrene (FS). We...... materials based on 2,3,5,6-tetrafiuoro-4-methoxy-styrene (TFMS). TFMS homopolymers as well as diblock copolymers with FS are produced by ATRP. Both types of novel polymers were subsequently demethylated and different side chains introduced on the resulting hydroxy sites....

  3. Stabilization of Proteins by Polymer Conjugation via ATRP

    Science.gov (United States)

    2008-08-31

    organophosphate hydrolase Organophosphorous hydrolase (OPH) that was sheathed in poly(2-ethylhexyl methacrylate-co-MPEG-methacrylate) was soluble in...applied to organophosphorous hydrolase. The enzyme was sheathed in copolymer matrix and dissolved in dichloromethane solution of poly(methyl methacrylate...lysozyme, asparaginase, organophosphorous hydrolase etc., by ATRP and by conventional pegylation. In vitro mouse and human serum stability study was

  4. Synthesis of 1-chloro-1-phenylethyl-telechelic polyisobutylene, a new potential macroinitiator by living cationic polymerization

    DEFF Research Database (Denmark)

    Ivan, Bela; Chen, Xianyi; Kops, Jørgen

    1998-01-01

    1-Chloro-1-phenylethyl-telechelic polyisobutylene (PIB) was synthesized by living carbocationic polymerization (LCCP). LCCP of isobutylene was induced by a difunctional initiator in conjunction with TiCl4 as coinitiator in the presence of N,N-dimethylacetamide in CH2Cl2/hexane (40:60 v/v) solvent...... mixture at -78 degrees C. After complete isobutylene conversion a small amount of styrene was added leading to a rapid crossover reaction and thus to the attachment of short outer polystyrene (PSt) blocks to the PIB segment. Quenching the living polymerization of styrene yielded 1-chloro-1-phenylethyl...... terminal groups. The resulting telechelic polymer (Cl-PSt-PIB-PSt-Cl) is a potential new macroinitiator for atom transfer radical polymerization of a variety of vinyl monomers....

  5. Hemocompatible surface of electrospun nanofibrous scaffolds by ATRP modification

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Wenjie [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Key Laboratory of Systems Bioengineering of Ministry of Education, Tianjin University, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Wang, Heyun [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832002 (China); Yang, Dazhi [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); An, Bo [Department of Orthopedics, Affiliated Hospital of Logistics University of Chinese People' s Armed Police Force, Tianjin 300162 (China); Zhang, Wencheng [Department of Physiology and Pathophysiology, Logistics University of Chinese People' s Armed Police Force, Tianjin 300162 (China); Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-10-15

    The electrospun scaffolds are potential application in vascular tissue engineering since they can mimic the nano-sized dimension of natural extracellular matrix (ECM). We prepared a fibrous scaffold from polycarbonateurethane (PCU) by electrospinning technology. In order to improve the hydrophilicity and hemocompatibility of the fibrous scaffold, poly(ethylene glycol) methacrylate (PEGMA) was grafted onto the fiber surface by surface-initiated atom transfer radical polymerization (SI-ATRP) method. Although SI-ATRP has been developed and used for surface modification for many years, there are only few studies about the modification of electrospun fiber by this method. The modified fibrous scaffolds were characterized by SEM, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The scaffold morphology showed no significant difference when PEGMA was grafted onto the scaffold surface. Based on the water contact angle measurement, the surface hydrophilicity of the scaffold surface was improved significantly after grafting hydrophilic PEGMA (P = 0.0012). The modified surface showed effective resistance for platelet adhesion compared with the unmodified surface. Activated partial thromboplastin time (APTT) of the PCU-g-PEGMA scaffold was much longer than that of the unmodified PCU scaffold. The cyto-compatibility of electrospun nanofibrous scaffolds was tested by human umbilical vein endothelial cells (HUVECs). The images of 7-day cultured cells on the scaffold surface were observed by SEM. The modified scaffolds showed high tendency to induce cell adhesion. Moreover, the cells reached out pseudopodia along the fibrous direction and formed a continuous monolayer. Hemolysis test showed that the grafted chains of PEGMA reduced blood coagulation. These results indicated that the modified electrospun nanofibrous scaffolds were potential application as artificial blood vessels. Highlights: • Electrospun nanofibrous scaffolds were successfully

  6. Functionalization of PEDOT by Click Chemistry and ATRP

    DEFF Research Database (Denmark)

    Hoffmann, Christian; Daugaard, Anders Egede

    Poly(3,4‐ethylenedioxythiophene) (PEDOT) is a conductive polymer which has received increasing attention and many developments have been investigated. PEDOT has been applied in many different areas such as biosensors or polymer solar cells. This work presents a modification of PEDOT films through...... Click Chemistry with alkynes followed by activator regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP) to develop PEDOT films with anti‐fouling properties through application of a model system based on a crosslinked surface of polystyrene PS‐N3....

  7. Synthesis of Reactive Polymers for Acrolein Capture Using AGET ATRP.

    Science.gov (United States)

    Beringer, Laura T; Li, Shaohua; Gilmore, Gary; Lister, John; Averick, Saadyah

    2015-10-05

    Acrolein is a toxic metabolite of the anticancer agent cyclophosphamide (CP). Current strategies to mitigate acrolein toxicity are insufficient, and in this brief article, we report the synthesis of well-defined low molecular weight block copolymers using activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) capable of reacting with the cytotoxic small molecule acrolein. Acrolein reactivity was introduced into the block copolymers via incorporation of either (a) aminooxy or (b) sulfhydryl groups. The cytoprotective effect of the polymers was compared to sodium 2-sulfanylethanesulfonate (mesna) the current gold standard for protection from CP urotoxicity, and we found that the polymers bearing sulfhydryl moieties demonstrated superior cytoprotective activity.

  8. Synthesis of polyacrylonitrile using AGET-ATRP in emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jing; Chen, Hou, E-mail: lduchenhou@hotmail.com; Liu, Delong; Ji, Naiyi; Zong, Guangxi

    2013-01-01

    The technique of activators generated by electron transfer for atom transfer radical polymerization (AGET-ATRP) of acrylonitrile (AN) has been first attempted in emulsion using the procedure of 'one-pot', 'two-step' with polyethylene glycol monooleyl ether (Brij 35) as surfactant, cupric chloride (CuCl{sub 2}) as catalyst, hexamethylenetetramine (HMTA) as ligand, carbon tetrachloride (CCl{sub 4}) as initiator and ascorbic acid (VC) as reducing agent. The polymerization proceeds in controlled/living manner as indicated by first-order kinetics of the polymerization rate with respect to the monomer concentration, linear increase of the molecular weight of polyacrylonitrile (PAN) with monomer conversion and narrow polydispersity. Monomer conversion increases initially with the increase of ligand HMTA and then decreases. The ratio of [AN1] to [AN2] at 1:3 not only gives better control on the molecular weight and the molecular weight distribution, but also provides a more rapid polymerization rate. The rate of polymerization shows a trend of increase along with CCl{sub 4} content. The apparent activation energy of the polymerization is calculated to be 46.6 kJ/mol. Chain extension of PAN with AN was also carried out and the chain extended PAN with 20520 molecular weight and 1.36 polydispersity was successfully obtained. - Graphical abstract: Kinetic plot for AGET ATRP of AN in emulsion AGET-ATRP of AN has first investigated in emulsion with HMTA as ligand, CCl{sub 4} as initiator and VC as reducing agent. The polymerizations have been successfully conducted in a controlled manner in the presence of air as evidenced by a linear first-order kinetic plot and linear increase of molecular weight with monomer conversion. Highlights: Black-Right-Pointing-Pointer AGET-ATRP of AN is first investigated in emulsion. Black-Right-Pointing-Pointer HMTA is used as ligand. Black-Right-Pointing-Pointer Chain extension of PAN with AN verifies the living nature of the

  9. Hemocompatible surface of electrospun nanofibrous scaffolds by ATRP modification.

    Science.gov (United States)

    Yuan, Wenjie; Feng, Yakai; Wang, Heyun; Yang, Dazhi; An, Bo; Zhang, Wencheng; Khan, Musammir; Guo, Jintang

    2013-10-01

    The electrospun scaffolds are potential application in vascular tissue engineering since they can mimic the nano-sized dimension of natural extracellular matrix (ECM). We prepared a fibrous scaffold from polycarbonateurethane (PCU) by electrospinning technology. In order to improve the hydrophilicity and hemocompatibility of the fibrous scaffold, poly(ethylene glycol) methacrylate (PEGMA) was grafted onto the fiber surface by surface-initiated atom transfer radical polymerization (SI-ATRP) method. Although SI-ATRP has been developed and used for surface modification for many years, there are only few studies about the modification of electrospun fiber by this method. The modified fibrous scaffolds were characterized by SEM, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The scaffold morphology showed no significant difference when PEGMA was grafted onto the scaffold surface. Based on the water contact angle measurement, the surface hydrophilicity of the scaffold surface was improved significantly after grafting hydrophilic PEGMA (P=0.0012). The modified surface showed effective resistance for platelet adhesion compared with the unmodified surface. Activated partial thromboplastin time (APTT) of the PCU-g-PEGMA scaffold was much longer than that of the unmodified PCU scaffold. The cyto-compatibility of electrospun nanofibrous scaffolds was tested by human umbilical vein endothelial cells (HUVECs). The images of 7-day cultured cells on the scaffold surface were observed by SEM. The modified scaffolds showed high tendency to induce cell adhesion. Moreover, the cells reached out pseudopodia along the fibrous direction and formed a continuous monolayer. Hemolysis test showed that the grafted chains of PEGMA reduced blood coagulation. These results indicated that the modified electrospun nanofibrous scaffolds were potential application as artificial blood vessels.

  10. Synthesis of polyacrylonitrile using AGET-ATRP in emulsion.

    Science.gov (United States)

    Ma, Jing; Chen, Hou; Liu, Delong; Ji, Naiyi; Zong, Guangxi

    2013-01-01

    The technique of activators generated by electron transfer for atom transfer radical polymerization (AGET-ATRP) of acrylonitrile (AN) has been first attempted in emulsion using the procedure of "one-pot", "two-step" with polyethylene glycol monooleyl ether (Brij 35) as surfactant, cupric chloride (CuCl2) as catalyst, hexamethylenetetramine (HMTA) as ligand, carbon tetrachloride (CCl4) as initiator and ascorbic acid (VC) as reducing agent. The polymerization proceeds in controlled/living manner as indicated by first-order kinetics of the polymerization rate with respect to the monomer concentration, linear increase of the molecular weight of polyacrylonitrile (PAN) with monomer conversion and narrow polydispersity. Monomer conversion increases initially with the increase of ligand HMTA and then decreases. The ratio of [AN1] to [AN2] at 1:3 not only gives better control on the molecular weight and the molecular weight distribution, but also provides a more rapid polymerization rate. The rate of polymerization shows a trend of increase along with CCl4 content. The apparent activation energy of the polymerization is calculated to be 46.6 kJ/mol. Chain extension of PAN with AN was also carried out and the chain extended PAN with 20520 molecular weight and 1.36 polydispersity was successfully obtained.

  11. Stable Poly(methacrylic acid Brush Decorated Silica Nano-Particles by ARGET ATRP for Bioconjugation

    Directory of Open Access Journals (Sweden)

    Marcello Iacono

    2015-08-01

    Full Text Available The synthesis of polymer brush decorated silica nano-particles is demonstrated by activator regeneration by electron transfer atom transfer radical polymerization (ARGET ATRP grafting of poly(tert-butyl methacrylate. ATRP initiator decorated silica nano-particles were obtained using a novel trimethylsiloxane derivatised ATRP initiator obtained by click chemistry. Comparison of de-grafted polymers with polymer obtained from a sacrificial initiator demonstrated good agreement up to 55% monomer conversion. Subsequent mild deprotection of the tert-butyl ester groups using phosphoric acid yielded highly colloidal and pH stable hydrophilic nano-particles comprising approximately 50% methacrylic acid groups. The successful bio-conjugation was achieved by immobilization of Horseradish Peroxidase to the polymer brush decorated nano-particles and the enzyme activity demonstrated in a conversion of o-phenylene diamine dihydrochloride assay.

  12. SYNTHESIS AND CHARACTERIZATION OF STRUCTURALLY WELL-DEFINED POLYMER-INORGANIC HYBRID NANOPARTICLES VIA ATRP

    Institute of Scientific and Technical Information of China (English)

    Jie Bai; Jie-bin Pang; Kun-yuan Qiu; Yen Wei

    2002-01-01

    Atom transfer radical polymerization (ATRP) using cuprous chloride/2,2'-bipyridine (bipy) was applied to graft polymerization of styrene on the surface of silica nanoparticles to synthesize polymer-inorganic hybrid nanoparticles. 2-(4-Chloromethylphenyl) ethyltriethoxysilane (CTES) was immobilized on the surface of silica nanoparticles through condensation reaction of the silanol groups on silica with triethoxysilane group of CTES. Then ATRP of St was initiated by this surface-modified silica nanoparticles bearing benzyl chloride groups, and formed PSt graft chains on the surface of silica nanoparticles. The thickness of the graft chains increased with reaction time. End group analysis confirmed the occurrence of ATRP. Thermal analysis indicated that thermal stabilization of these resulting hybrid nanoparticles also increases with polymerization conversion. The results above show that this "grafting from" reaction could be used for the preparation of polymer-inorganic hybrid nanoparticles with controlled structure of the polymer's end groups.

  13. Functional brush-decorated poly(globalide) films by ARGET-ATRP for bioconjugation.

    Science.gov (United States)

    Ates, Zeliha; Audouin, Fabrice; Harrington, Amy; O'Connor, Brendan; Heise, Andreas

    2014-11-01

    Formation of hydroxyl functionalized poly(macrolactone) films was achieved by a combination of enzymatic ring opening polymerization of globalide and thiol-ene coupling reactions. Reaction with α-bromoisobutyryl bromide yielded ATRP initiator functional films. Efficient activator regeneration by electron transfer (ARGET) ATRP was employed for the polymerization of tert-butyl acrylate (tBA) and NIPAM from the initiator decorated surfaces. Deprotection of the tert-butyl ester decorated polymer films yielded carboxylic acid groups for convenient attachment of biomolecule. The successful conjugation of green fluorescent protein (eGFP) and active enzyme chitobiase (Chb) on densely poly(acrylic acid)-functionalized polyester films is demonstrated.

  14. Cellulose-based graft copolymers prepared by simplified electrochemically mediated ATRP

    Directory of Open Access Journals (Sweden)

    P. Chmielarz

    2017-02-01

    Full Text Available Brush-shaped block copolymer with a dual hydrophilic poly(acrylic acid-block-poly(oligo(ethylene glycol acrylate (PAA-b-POEGA arms was synthesized for the first time via a simplified electrochemically mediated ATRP (seATRP under both constant potential electrolysis and constant current electrolysis conditions, utilizing only 30 ppm of catalyst complex. The polymerization conditions were optimized to provide fast reactions while employing low catalyst concentrations and preparation of cellulose-based brush-like copolymers with narrow molecular weight distributions. The results from proton nuclear magnetic resonance (1H NMR spectral studies support the formation of cellulose-based graft (copolymers. It is expected that these new polymer brushes may find application as pH- and thermo-sensitive drug delivery systems.

  15. The Synthesis and Characterisation of Novel Amide Initiators for the ATRP of OEGMA

    OpenAIRE

    Kliene, Aaron

    2015-01-01

    Whilst atom transfer radical polymerisation (ATRP) has been shown to be a robust and versatile technique for the creation of a wide range of polymers from many different initiators, there is relatively little previous research into the usage of initiators containing amide functionality. Low initiator efficiencies, often resulting in higher than predicted molecular weight parameters, and slow polymerisations with variable rates of reaction are generally reported when amide initiators have prev...

  16. ATRP-based synthesis and characterization of light-responsive coatings for transdermal delivery systems

    Science.gov (United States)

    Pauly, Anja C.; Schöller, Katrin; Baumann, Lukas; Rossi, René M.; Dustmann, Kathrin; Ziener, Ulrich; de Courten, Damien; Wolf, Martin; Boesel, Luciano F.; Scherer, Lukas J.

    2015-06-01

    The grafting of poly(hydroxyethylmethacrylate) on polymeric porous membranes via atom transfer radical polymerization (ATRP) and subsequent modification with a photo-responsive spiropyran derivative is described. This method leads to photo-responsive membranes with desirable properties such as light-controlled permeability changes, exceptional photo-stability and repeatability of the photo-responsive switching. Conventional track etched polyester membranes were first treated with plasma polymer coating introducing anchoring groups, which allowed the attachment of ATRP-initiator molecules on the membrane surface. Surface initiated ARGET-ATRP of hydroxyethylmethacrylate (where ARGET stands for activator regenerated by electron transfer) leads to a membrane covered with a polymer layer, whereas the controlled polymerization procedure allows good control over the thickness of the polymer layer in respect to the polymerization conditions. Therefore, the final permeability of the membranes could be tailored by choice of pore diameter of the initial membranes, applied monomer concentration or polymerization time. Moreover a remarkable switch in permeability (more than 1000%) upon irradiation with UV-light could be achieved. These properties enable possible applications in the field of transdermal drug delivery, filtration, or sensing.

  17. Automated ARGET ATRP Accelerates Catalyst Optimization for the Synthesis of Thiol-Functionalized Polymers.

    Science.gov (United States)

    Siegwart, Daniel J; Leiendecker, Matthias; Langer, Robert; Anderson, Daniel G

    2012-02-14

    Conventional synthesis of polymers by ATRP is relatively low throughput, involving iterative optimization of conditions in an inert atmosphere. Automated, high-throughput controlled radical polymerization was developed to accelerate catalyst optimization and production of disulfide-functionalized polymers without the need of an inert gas. Using ARGET ATRP, polymerization conditions were rapidly identified for eight different monomers, including the first ARGET ATRP of 2-(diethylamino)ethyl methacrylate and di(ethylene glycol) methyl ether methacrylate. In addition, butyl acrylate, oligo(ethylene glycol) methacrylate 300 and 475, 2-(dimethylamino)ethyl methacrylate, styrene, and methyl methacrylate were polymerized using bis(2-hydroxyethyl) disulfide bis(2-bromo-2-methylpropionate) as the initiator, tris(2-pyridylmethyl)amine as the ligand, and tin(II) 2-ethylhexanoate as the reducing agent. The catalyst and reducing agent concentration was optimized specifically for each monomer, and then a library of polymers was synthesized systematically using the optimized conditions. The disulfide-functionalized chains could be cleaved to two thiol-terminated chains upon exposure to dithiothreitol, which may have utility for the synthesis of polymer bioconjugates. Finally, we demonstrated that these new conditions translated perfectly to conventional batch polymerization. We believe the methods developed here may prove generally useful to accelerate the systematic optimization of a variety of chemical reactions and polymerizations.

  18. Surface tailoring for selective endothelialization and platelet inhibition via a combination of SI-ATRP and click chemistry using Cys-Ala-Gly-peptide.

    Science.gov (United States)

    Khan, Musammir; Yang, Jing; Shi, Changcan; Lv, Juan; Feng, Yakai; Zhang, Wencheng

    2015-07-01

    Surface tailoring is an attractive approach to enhancing selective endothelialization, which is a prerequisite for current vascular prosthesis applications. Here, we modified polycarbonate urethane (PCU) surface with both poly(ethylene glycol) and Cys-Ala-Gly-peptide (CAG) for the purpose of creating a hydrophilic surface with targeting adhesion of endothelial cells (ECs). In the first step, PCU-film surface was grafted with poly(ethylene glycol) methacrylate (PEGMA) to covalently tether hydrophilic polymer brushes via surface initiated atom transfer radical polymerization (SI-ATRP), followed by grafting of an active monomer pentafluorophenyl methacrylate (PFMA) by a second ATRP. The postpolymerization modification of the terminal reactive groups with allyl amine molecules created pendant allyl groups, which were subsequently functionalized with cysteine terminated CAG-peptide via photo-initiated thiol-ene click chemistry. The functionalized surfaces were characterized by water contact angle and XPS analysis. The growth and proliferation of human ECs or human umbilical arterial smooth muscle cells on the functionalized surfaces were investigated for 1, 3 and 7 day/s. The results indicated that these peptide functionalized surfaces exhibited enhanced EC adhesion, growth and proliferation. Furthermore, they suppressed platelet adhesion in contact with platelet-rich plasma for 2h. Therefore, these surfaces with EC targeting ligand could be an effective anti-thrombogenic platform for vascular tissue engineering application.

  19. Controlled release of cortisone drugs from block copolymers synthetized by ATRP

    Science.gov (United States)

    Valenti, G.; La Carta, S.; Mazzotti, G.; Rapisarda, M.; Perna, S.; Di Gesù, R.; Giorgini, L.; Carbone, D.; Recca, G.; Rizzarelli, P.

    2016-05-01

    Diseases affecting posterior eye segment, like macular edema, infection and neovascularization, may cause visual impairment. Traditional treatments, such as steroidal-drugs intravitreal injections, involve chronic course of therapy usually over a period of years. Moreover, they can require frequent administrations of drug in order to have an adequately disease control. This dramatically reduce patient's compliance. Efforts have been made to develop implantable devices that offer an alternative therapeutic approach to bypass many challenges of conventional type of therapy. Implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their slow release in the specific site. Polymeric materials can play an essential role in modulating drug delivery and their use in such field has become indispensable. During last decades, acrylic polymers have obtained growing interest. Biocompatibility and chemical properties make them extremely versatile, allowing their use in many field such as biomedical. In particular, block methacrylate copolymer with a balance of hydrophilic and hydrophobic properties can be suitable for prolonged DDS in biomedical devices. In this work, we focused on the realization of a system for controlled and long term release of betamethasone 17,21-dipropionate (BDP), a cortisone drug, from methacrylic block copolymers, to be tested in the treatment of the posterior eye's diseases. Different series of methyl methacrylate/hydroxyethyl methacrylate (MMA/HEMA) block and random copolymers, with different monomer compositions (10-60% HEMA), were synthetized by Atom Transfer Radical Polymerization (ATRP) to find the best hydrophilic/hydrophobic ratio, able to ensure optimal kinetic release. Copolymer samples were characterized by NMR spectroscopy (1H-NMR, 13C-NMR, CosY), SEC, TGA and DSC. Monitoring of drug release from films loaded with BDP was carried out by HPLC analysis. Evaluation of different kinetic

  20. Strategies towards Novel Carbon Fiber Precursors: the Research Results on the Synthesis of PAN Copolymers via AGET ATRP and on Lignin as a Precursor

    Directory of Open Access Journals (Sweden)

    Spyridon Soulis

    2015-11-01

    Full Text Available The aim of this work is the presentation of two different approximations for improving the production of carbon fibers through the introduction of alternative precursors. The first approach concerns the development of novel polyacrylonitrile block copolymers through activators’ generated by electron transfer-atom transfer radical polymerization (AGET-ATRP reaction mechanism in microemulsion; the novel polymers are envisaged to contain a structure that will be more efficiently oxidatively stabilized and/or carbonized, with the ultimate target of CFs with improved properties. The second approximation aims at the introduction of lignin as efficient CFs precursor; this approach aims at reducing the cost of the process and increasing the production yield. Pyrolysis together with oxidative stabilization of lignin were investigated, as well as the effects on structure and thermal behavior of blending with thermoplastics. Thus far, both these methodologies exhibited significant potential and will be further developed towards full scale industrial application.

  1. Star polymers by ATRP of styrene and acrylates employing multifunctional initiators

    DEFF Research Database (Denmark)

    Jankova, Katja Atanassova; Bednarek, Melania; Hvilsted, Søren

    2005-01-01

    scission of the ester linkages and the second step corresponds to the normal PS degradation. Star poly(methyl acrylates) with various cores are likewise prepared in a controlled manner by ATRP of methyl acrylate in bulk and in solution at 6080 degrees C with the 1,1,4,7,7-pentamethyldiethylene triamine...... ligand. Under these conditions, higher conversions were possible still maintaining low PDI signaling controlled star growth. Multiarm stars of poly(n-butyl acrylate) and poly(n-hexyl acrylate) with controlled characteristics have also been prepared....

  2. Immobilization of α-amylase onto poly(glycidyl methacrylate) grafted electrospun fibers by ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Oktay, Burcu; Demir, Serap; Kayaman-Apohan, Nilhan, E-mail: napohan@marmara.edu.tr

    2015-05-01

    In this study, novel α-amylase immobilized poly(vinyl alcohol) (PVA) nanofibers were prepared. The PVA nanofiber surfaces were functionalized with 2-bromoisobutyryl bromide (BiBBr) and followed by surface initiated atom transfer radical polymerization (SI-ATRP) of glycidyl methacrylate (GMA). The morphology of the poly(glycidyl methacrylate) (PGMA) grafted PVA nanofibers was characterized by scanning electron microscopy (SEM). Also PGMA brushes were confirmed by X-ray photo electron microscopy (XPS). α-Amylase was immobilized in a one step process onto the PGMA grafted PVA nanofiber. The characteristic properties of the immobilized and free enzymes were examined. The thermal stability of the enzyme was improved and showed maximum activity at 37 °C by immobilization. pH values of the maximum activity of the free and immobilized enzymes were also found at 6.0 and 6.5, respectively. Free enzyme lost its activity completely within 15 days. The immobilized enzyme lost only 23.8% of its activity within 30 days. - Highlights: • Electrospun photocrosslinkable PVA nanofiber was prepared. • PGMA brushes were conducted on PVA nanofiber via SI-ATRP. • The immobilized enzyme showed maximum activity at pH 6.0 and at 37 °C. • Functionalized nanofibers may be used as promising supports for enzyme immobilization.

  3. Biocleavable graphene oxide based-nanohybrids synthesized via ATRP for gene/drug delivery

    Science.gov (United States)

    Yang, Xinchao; Zhao, Nana; Xu, Fu-Jian

    2014-05-01

    Graphene oxide (GO) has been proven to be promising in many biomedical fields due to its biocompatibility, unique conjugated structure, easily tunable surface functionalization and facile synthesis. In this work, a flexible two-step method was first developed to introduce the atom transfer radical polymerization (ATRP) initiation sites containing disulfide bonds onto GO surfaces. Surface-initiated ATRP of (2-dimethyl amino)ethyl methacrylate (DMAEMA) was then employed to tailor the GO surfaces in a well-controlled manner, producing a series of organic-inorganic hybrids (termed as SS-GPDs) for highly efficient gene delivery. Under reducible conditions, the PDMAEMA side chains can be readily cleavable from the GO backbones, benefiting the resultant gene delivery process. Moreover, due to the conjugated structure of the graphene basal plane, SS-GPD can attach and absorb aromatic, water insoluble drugs, such as 10-hydroxycamptothecin (CPT), producing SS-GPD-CPT. The MTT assay and the simultaneous double-staining procedure revealed that SS-GPD-CPT possessed a high potency of killing cancer cells in vitro. With a high aqueous solubility and coulombic interaction with cell membrane, SS-GPDs may have great potential in gene/drug delivery fields.

  4. Copolyacrylates with phenylalanine and anthracene entities prepared by ATRP and microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Buruiana, E.C., E-mail: emilbur@icmpp.r [Romanian Academy, Petru Poni Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41A, 700487 Iasi (Romania); Murariu, Mioara; Buruiana, Tinca [Romanian Academy, Petru Poni Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41A, 700487 Iasi (Romania)

    2010-10-15

    In this study, two amino acid copolymers containing anthracene incorporated either on the one end, poly(N-acryloyl-L-phenylalanine-co-methyl methacrylate)-1 or as pendant groups, poly-(N-acryloyl-L-phenylalanine-co-methyl methacrylate)-2 were prepared directly from N-acryloyl-L-phenylalanine (APhe) and methyl methacrylate (MMA) through atom transfer radical polymerization (ATRP) and microwave-assisted synthesis. In the first case, 9-(chloromethyl)anthracene was used as an ATRP-initiator to obtain a copolymer that contains amino acid sequences and anthracene end-capped units (0.03 molar fraction). Rapid synthesis of copolymer under microwave irradiation (250 W) in the presence of 1,1'-azobis(cyclohexanecarbonitrile) used as an initiator was followed of a functionalization of the formed copolymer with an anthracene derivative yielding copolyacrylate with pendant anthracene (0.02 molar fraction). The structure of the copolymers was verified by {sup 1}H NMR, UV-Vis and FTIR spectroscopy, gel permeation chromatography (GPC), and fluorescence spectroscopy. The fluorescence quenching process of anthracene which exists in copolymers by FeCl{sub 3}, cobalt acetate, nitrobenzene, maleic anhydride, diethylaniline and nitromethane in DMF solutions shows that this involves an electron transfer between the excited state anthracene and the present transitional metal cations, more efficiently being FeCl{sub 3} for poly-(APhe-co-MMA)-1 and cobalt acetate for the latter copolymer.

  5. Photoresponsive Azopolyester–PMMA Block Copolymers Obtained by Combination of ATRP, Polycondensation, and “Click” Chemistry

    DEFF Research Database (Denmark)

    Berges, Cristina; Javakhishvili, Irakli; Hvilsted, Søren

    2012-01-01

    Novel azobenzene‐containing block copolymers (BCs) with a polyester block bearing azobenzene moieties in the side chain and a poly (methyl methacrylate) (PMMA) block have been synthesized by the combination of atom transfer radical polymerization (ATRP), polycondensation, and “click” chemistry. T...

  6. Versatile procedure for site-specific grafting of polymer brushes on patchy particles via atom transfer radical polymerization (ATRP)

    NARCIS (Netherlands)

    Van Ravensteijn, Bas G P; Kegel, Willem K.

    2016-01-01

    We report the preparation of chemically anisotropic colloidal dumbbells of which one lobe is functionalized with chemical handles in the form of chlorine groups. The chlorines are easily converted to azides and subsequently to active initiators for Atom Transfer Radical Polymerization (ATRP) by Clic

  7. A Facile Strategy for Catalyst Separation and Recycling Suitable for ATRP of Hydrophilic Monomers Using a Macroligand.

    Science.gov (United States)

    Jiang, Xiaowu; Wu, Jian; Zhang, Lifen; Cheng, Zhenping; Zhu, Xiulin

    2016-01-01

    How to simply and efficiently separate and recycle catalyst has still been a constraint for the wide application of atom transfer radical polymerization (ATRP), especially for the polymerization systems with hydrophilic monomers because the polar functional groups may coordinate with transition metal salts, resulting in abundant catalyst residual in the resultant water-soluble polymers. In order to overcome this problem, a latent-biphasic system is developed, which can be successfully used for ATRP catalyst separation and recycling in situ for various kinds of hydrophilic monomers for the first time, such as poly(ethylene glycol) monomethyl ether methacrylate (PEGMA), 2-hydroxyethyl methacrylate (HEMA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), N,N-dimethyl acrylamide (DMA), and N-isopropylacrylamide (NIPAM). Herein, random copolymer of octadecyl acrylate (OA), MA-Ln (2-(bis(pyridin-2-ylmethyl)amino)ethyl acrylate), and POA-ran-P(MA-Ln) is designed as the macroligand, and heptane/ethanol is selected as the biphasic solvent. Copper(II) bromide (CuBr2 ) is employed as the catalyst, PEG-bound 2-bromo-2-methylpropanoate (PEG350 -Br) as the water-soluble ATRP initiator and 2,2'-azobis(isobutyronitrile) (AIBN) as the azo-initiator to establish an ICAR (initiators for continuous activator regeneration) ATRP system. Importantly, well-defined water-soluble polymers are obtained even though the recyclable catalyst is used for sixth times.

  8. Iron-Mediated Homogeneous ICAR ATRP of Methyl Methacrylate under ppm Level Organometallic Catalyst Iron(III Acetylacetonate

    Directory of Open Access Journals (Sweden)

    Jian Wu

    2016-01-01

    Full Text Available Atom Transfer Radical Polymerization (ATRP is an important polymerization process in polymer synthesis. However, a typical ATRP system has some drawbacks. For example, it needs a large amount of transition metal catalyst, and it is difficult or expensive to remove the metal catalyst residue in products. In order to reduce the amount of catalyst and considering good biocompatibility and low toxicity of the iron catalyst, in this work, we developed a homogeneous polymerization system of initiators for continuous activator regeneration ATRP (ICAR ATRP with just a ppm level of iron catalyst. Herein, we used oil-soluble iron (III acetylacetonate (Fe(acac3 as the organometallic catalyst, 1,1′-azobis (cyclohexanecarbonitrile (ACHN with longer half-life period as the thermal initiator, ethyl 2-bromophenylacetate (EBPA as the initiator, triphenylphosphine (PPh3 as the ligand, toluene as the solvent and methyl methacrylate (MMA as the model monomer. The factors related with the polymerization system, such as concentration of Fe(acac3 and ACHN and polymerization kinetics, were investigated in detail at 90 °C. It was found that a polymer with an acceptable molecular weight distribution (Mw/Mn = 1.43 at 45.9% of monomer conversion could be obtained even with 1 ppm of Fe(acac3, making it needless to remove the residual metal in the resultant polymers, which makes such an ICAR ATRP process much more industrially attractive. The “living” features of this polymerization system were further confirmed by chain-extension experiment.

  9. Pentafluorostyrene: A valuable and flexible material design tool when mastered by ATRP

    DEFF Research Database (Denmark)

    Hvilsted, Søren

    been exploited by the nucleophilic substitution methodology to create numerous other monomers. Two very recent applications have exploited short alkyne initiated poly(pentafluorostyrene)s. The first example is development of polyelectrolyte materials comparable to the industrial fuel cells standard......Pentafluorostyrene is an intriguing monomer and has turned out to be an indispensable tool in the architecture of various functional materials. The ATRP merits with pentafluorostyrene was revealed a decade ago and since then especially the lability of the para-fluorine of pentafluorostyrene has...... Nafion®. Our solution to this polyelectrolyte challenge is the combination of a thermally and chemically very stable backbone PSU (Mn ∼40,000 Da), which is also an excellent film forming material, with poly(pentafluorostyrene) grafts that additionally ensures high thermal stability as a very promising...

  10. Self-assembled Block Copolymers with Various Architectures Designed by ATRP

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja

    /L do to hydrophobic association of the PS blocks in the corona. Effect of the hydrophobe length and polymer topology has been additionally investigated (6). iv. Hydrophilic nanoporous polymers with various morphologies and pore size (7) have been mastered by novel synthetic strategies using two...... of the macromolecular building blocks they self assemble in attractive morphologies and exhibit interesting rheology. The designed at the Danish Polymer Centre by ATRP self-assembling block copolymers will be demonstrated by several examples: i. Diblock copolymers of PMMA with side chain liquid crystalline (LC...... methodologies, which will be discussed. In contact with water, they showed spontaneous water uptake (8). References (1). Hansen, N.M.L.; Jankova, K.; Hvilsted, S. European Polymer Journal 43(2), pp 255-293 (2007); Bednarek, M.; Jankova, K.; Hvilsted, S. J. Polym. Sci., Part A: Polym. Chem. 45, pp 333-340 (2007...

  11. Optimizing conditions of preparation of thermoresponsive SiO{sub 2}-POEGMA particles via AGET-ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Du, Zhiping, E-mail: duzhiping@sxu.edu.cn [Institute of Resources and Environment Engineering, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006 (China); China Research Institute of Daily Chemical Industry, No.34 Wenyuan Road, Taiyuan 030001 (China); Sun, Xiaofeng; Tai, Xiumei; Wang, Guoyong; Liu, Xiaoying [China Research Institute of Daily Chemical Industry, No.34 Wenyuan Road, Taiyuan 030001 (China)

    2015-02-28

    Graphical abstract: - Highlights: • Thermosensitive SiO{sub 2} nanoparticles were prepared with POEGMA via AGET-ATRP. • Reaction conditions were optimized. • Thermosensitive properties of SiO{sub 2}-POEGMA particles were pronounced. - Abstract: Thermosensitive poly(ethylene glycol) methyl ether methacrylate (POEGMA) was grafted on SiO{sub 2} nanoparticles using activators generated by electron transfer atom transfer radical polymerization (AGET-ATRP) technique. The effects of the amount of ligand, catalyst, ascorbic acid and monomer, as well as the reaction temperature and time were systematically investigated and optimized to get a high grafting density. The structure of the hybrid materials was characterized by Fourier transform infrared (FTIR) spectroscopy, and the morphology was characterized by transmission electron microscopy (TEM) observations. Thermosensitive properties of SiO{sub 2}-POEGMA particles were investigated at different grafting densities by turbidity measurements.

  12. Grafting of carboxybetaine brush onto cellulose membranes via surface-initiated ARGET-ATRP for improving blood compatibility.

    Science.gov (United States)

    Wang, Miao; Yuan, Jiang; Huang, Xiaobo; Cai, Xianmei; Li, Li; Shen, Jian

    2013-03-01

    Grafting-from has proven to be a very effective way to create high grafting densities and well-controlled polymer chains on different kinds of surfaces. In this work, we aim to graft zwitterionic brush from cellulose membrane (CM) via ARGET-ATRP (Activator Regenerated by Electron Transfer ATRP) method indirectly for blood compatibility improvement. Characterization of the CM substrates before and after modification was carried out by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle measurements, X-ray photoelectron spectroscopy analysis, and atomic force microscopy, respectively. The results demonstrated zwitterionic brushes were successfully grafted on the CM surfaces, and the content of the grafted layer increased gradually with the polymerization time. The platelet adhesion, hemolytic test and plasma protein adsorption results indicated the cellulose membrane had significantly excellent blood compatibility featured on lower platelet adhesion and protein adsorption without causing hemolysis. The functionalized cellulose substrate could have a great potential usage for biomedical applications.

  13. Controlled in situ formation of polyacrylamide hydrogel on PET surface via SI-ARGET-ATRP for wound dressings

    Energy Technology Data Exchange (ETDEWEB)

    Nazari Pour, Sedigheh [Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Ghugare, Shivkumar V. [Department of Textile Science, Faculty of Human Ecology, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Wiens, Richard; Gough, Kathleen [Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Liu, Song, E-mail: Song.Liu@umanitoba.ca [Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Department of Textile Science, Faculty of Human Ecology, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Department of Biosystems Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada)

    2015-09-15

    Graphical abstract: - Highlights: • We grow poly(acrylamide) (PAM) hydrgol from a polymer surface in a controlled way. • Divinyl crosslinker doesn't compromise the control chain growth feature of ARGET-ATRP. • ATR-FTIR-FPA images (spatial resolution 220 nm) reveal a uniform grafting of PAM. • PAM grafted wound dressing can be dual functional: low-adherent and antibacterial. - Abstract: Well-defined polyacrylamide (PAM) hydrogel was synthesized on the surface of poly(ethylene terephthalate) (PET) film via surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET-ATRP). Following the deposition of an ATRP initiator (2-bromoisobutyrylbromide) on PET film, PAM hydrogel was grafted from the functionalized PET surface via ARGET-ATRP. XPS and FTIR-ATR confirmed that PAM hydrogel was successfully grafted on the PET surface. Results from AFM, SEM, and FTIR-FPA microscopic investigations showed that PAM hydrogel uniformly covers the surface of PET film. The grafting yield increases linearly with increasing reaction time, indicating that the growth of PAM hydrogel on the surface of PET is well controlled. In a cell adhesion assay, PAM hydrogel grafted PET films (PAM hydrogel-g-PET) showed low adhesion to keratinocyte cells. To impart PAM hydrogel-g-PET with antibacterial function, AgNPs were self-assembled along the amide side chains of PAM hydrogel. AgNPs loaded-PAM hydrogel-g-PET shows 99% reduction in the number of multidrug-resistant Pseudomonas aeruginosa within 3 h contact.

  14. Functionalization of graphene and grafting of temperature-responsive surfaces from graphene by ATRP 'on water'

    Energy Technology Data Exchange (ETDEWEB)

    Ren Lulu; Huang Shu; Zhang Chao; Wang Ruiyu [Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science (China); Tjiu, Weng Weei [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR) (Singapore); Liu Tianxi, E-mail: txliu@fudan.edu.cn [Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science (China)

    2012-06-15

    Water-dispersible graphene with temperature-responsive surfaces has successfully been synthesized by grafting poly(N-isopropylacrylamide) (PNIPAM) from graphene via surface-initiated atom transfer radical polymerization (ATRP). First, graphene surfaces are functionalized with aminophenol groups by diazonium reaction on water. Subsequently, bromoisobutyrate groups are covalently attached to the phenol-functionalized graphene (G-OH) surface by esterification of 2-bromoisobutyrate with the hydroxyl groups, forming bromoisobutyrate-functionalized graphene (G-Br). Finally, PNIPAM is then grafted from G-Br via ATRP. Data from Raman spectroscopy, {sup 1}H NMR, and transmission electron microscopy (TEM) confirm that PNIPAM chains grow from graphene by ATRP. Thermogravimetric analysis shows that the amount of PNIPAM grown from the graphene increases with the increase of monomer ratios. TEM images also show that functionalized polymer structures (PNIPAM cluster or agglutination) on graphene sheets can be well tuned by controlled polymerization. The obtained graphene-PNIPAM (G-PNIPAM) composite has PNIPAM surface which is highly sensitive to the temperature change. This temperature-responsive and water-dispersible G-PNIPAM composite may find potential applications in environmental devices as well as controlled release drug delivery.

  15. Induction heating for surface triggering styrene polymerization on titanium modified with ATRP initiator.

    Science.gov (United States)

    Barthélémy, Bastien; Devillers, Sébastien; Minet, Isabelle; Delhalle, Joseph; Mekhalif, Zineb

    2011-02-15

    Titanium and its alloys present high interests for technological applications due to their high corrosion resistance, mechanical properties and biocompatibility. In combination with these remarkable characteristics, some Ti applications require specific surface properties that can be imparted with suitable surface functionalizations of the TiO(2) oxide layer. The present work aims to study the surface-initiated ATR polymerization of styrene on titanium substrates, using grafted 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid as initiator and to compare the impact of two different heating ways on the efficiency of this polymerization: induction vs. conventional heating. The ability of the initiator to bind titanium substrates and act as an initiator for ATRP of styrene is investigated: both heating conditions led to the polymerization of styrene on modified titanium substrates. However, induction heating appeared to be much more efficient than conventional heating, leading to the formation of a thicker, much denser polystyrene layer than conventional heating after only 1h of polymerization.

  16. A method to modify PVDF microfiltration membrane via ATRP with low-temperature plasma pretreatment

    Science.gov (United States)

    Han, Yu; Song, Shuijun; Lu, Yin; Zhu, Dongfa

    2016-08-01

    The hydrophilic modification of a polyvinylidene fluoride (PVDF) microfiltration membrane via pretreatment with argon plasma and direct surface-initiated atom transfer radical polymerization (ATRP) was studied. Both modified and unmodified PVDF membranes were characterized by Fourier transform infrared spectroscopy (FTIR), water contact angle, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and pore size distribution measurements. FTIR and XPS spectra confirmed that sulfobetaine methacrylate (SBMA) had been grafted onto the membrane surface. The initial contact angle decreased from 87.0° to 29.8° and a water drop penetrated into the modified membrane completely in 8 s. The pore size distribution of the modified membrane exhibited a smaller mean value than that of the original membrane. The antifouling properties of the modified PVDF membrane were evaluated by a filtration test using bovine serum albumin (BSA) solution. The results showed that the initial flux of the modified membrane increased from 2140.1 L/m2 h to 2812.7 L/m2 h and the equilibrium flux of BSA solution increased from 31 L/m2 h to 53 L/m2 h.

  17. Anti-fouling surfaces by combined molecular self-assembly and surface-initiated ATRP for micropatterning active proteins.

    Science.gov (United States)

    Xiu, K M; Cai, Q; Li, J S; Yang, X P; Yang, W T; Xu, F J

    2012-02-01

    A simple method by combined molecular self assembly and surface-initiated atom transfer radical polymerization (SI-ATRP) was proposed to prepare a biologically inert surface for micropatterning active proteins. The MPEG microdomains having a short terminal poly(ethylene glycol) (PEG) unit were prepared by self assembly of 2-(methyoxy(polyethylenoxy) propyl)trimethoxy silane (MPEG-silane). The remaining local regions or poly(poly(ethylene glycol)methyl ether methacrylate-co-glycidyl methacrylate) (P(PEGMEMA-co-GMA)) microdomains were produced via SI-ATRP of PEGMEMA and GMA comonomers. The epoxy groups of the P(PEGMEMA-co-GMA) microdomains were used directly for covalent coupling of an active protein (human immunoglobulin or IgG) via the ring-opening reaction to produce the IgG-coupled microdomains. The IgG-coupled microdomains interact only and specifically with target anti-IgG, while the other antifouling microregions from self-assembled monolayers with short terminal PEG units effectively prevent specific and non-specific protein fouling. When extended to other active biomolecules, microarrays for specific and non-specific analyte interactions with a high signal-to-noise ratio could be readily tailored.

  18. Zwitterionic polymer functionalization of polysulfone membrane with improved antifouling property and blood compatibility by combination of ATRP and click chemistry.

    Science.gov (United States)

    Xiang, Tao; Lu, Ting; Xie, Yi; Zhao, Wei-Feng; Sun, Shu-Dong; Zhao, Chang-Sheng

    2016-08-01

    The chemical compositions are very important for designing blood-contacting membranes with good antifouling property and blood compatibility. In this study, we propose a method combining ATRP and click chemistry to introduce zwitterionic polymer of poly(sulfobetaine methacrylate) (PSBMA), negatively charged polymers of poly(sodium methacrylate) (PNaMAA) and/or poly(sodium p-styrene sulfonate) (PNaSS), to improve the antifouling property and blood compatibility of polysulfone (PSf) membranes. Attenuated total reflectance-Fourier transform infrared spectra, X-ray photoelectron spectroscopy and water contact angle results confirmed the successful grafting of the functional polymers. The antifouling property and blood compatibility of the modified membranes were systematically investigated. The zwitterionic polymer (PSBMA) grafted membranes showed good resistance to protein adsorption and bacterial adhesion; the negatively charged polymer (PNaSS or PNaMAA) grafted membranes showed improved blood compatibility, especially the anticoagulant property. Moreover, the PSBMA/PNaMAA modified membrane showed both antifouling property and anticoagulant property, and exhibited a synergistic effect in inhibiting blood coagulation. The functionalization of membrane surfaces by a combination of ATRP and click chemistry is demonstrated as an effective route to improve the antifouling property and blood compatibility of membranes in blood-contact.

  19. An Undergraduate Chemistry Laboratory: Synthesis of Well-Defined Polymers by Low-Catalyst-Concentration ATRP and Postpolymerization Modification to Fluorescent Materials

    Science.gov (United States)

    Tsarevsky, Nicolay V.; Woodruf, Shannon R.; Wisian-Neilson, Patty J.

    2016-01-01

    A two-session experiment is designed to introduce undergraduate students to concepts in catalysis, transition metal complexes, polymer synthesis, and postpolymerization modifications. In the first session, students synthesize poly(glycidyl methacrylate) via low-catalyst-concentration atom transfer radical polymerization (ATRP). The…

  20. Polystyrene-Poly(sodium methacrylate) Amphiphilic Block Copolymers by ATRP : Effect of Structure, pH, and Ionic Strength on Rheology of Aqueous Solutions

    NARCIS (Netherlands)

    Raffa, Patrizio; Brandenburg, Piter; Wever, Diego A. Z.; Broekhuis, Antonius A.; Picchioni, Francesco

    2013-01-01

    Three well-defined polystyrene-poly(sodium methacrylate) amphiphilic block copolymers characterized by different molecular architecture (diblock, triblock, and four-arm star) have been synthesized by ATRP. The rheology of their water solutions has been evaluated by measuring dynamic moduli and shear

  1. MICRON CORE-SHELL PARTICLES PREPARED BY GRAFTING POLYMERIZATION OF METHYL METHACRYLATE FROM NARROW DISPERSE SURFACE OF CHLOROMETHYLATED POLYDIVINYLBENZENE VIA ATRP

    Institute of Scientific and Technical Information of China (English)

    Yu-zeng Zhao; Xin-lin Yang; Wen-qiang Huang

    2005-01-01

    Grafting of poly(methyl methacrylate) from narrow disperse polymer particles by surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) particles were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as the stabilizer. Chloromethylated PDVB was used as initiating core sites for subsequent ATRP of methyl methacrylate with CuBr/bpy as catalyst system. It was found that poly(methyl methacrylate) was grafted not only from the particle surfaces but also from within a thin shell layer, leading to particles size increases from 2.38-3.00 μm with a core-shell structure particles. The grafted core-shell particles were characterized with FTIR, SEM, DSC.

  2. Synthesis of Comb HPEG/PMA and HPEG/PAA via ATRP%ATRP法合成梳形结构的HPEG/PMA和HPEG/PAA

    Institute of Scientific and Technical Information of China (English)

    赵莉; 任殿福; 田卫星; 王宏; 陈仲; 韩兆让

    2014-01-01

    Comb methyl allyl polyethenoxy ether-polymethyl acrylate (HPEG/PMA)was synthesized with atom transfer radical polymerization (ATRP).FT-IR and 1 H NMR were used to identify the structure of HPEG/PMA.The results show that we successfully synthesized comb-like HPEG/PMA.Gel permeation chromatography (GPC)was used to characterize the molecular weight and molecular weight distribution.The molecular weight was 7.7×103 and molecular weight distribution was 1 .1 1 .It indicates that the synthesis of HPEG/PAA with ATRP has good controllability.The HPEG/PMA was hydrolyzed with NaOH V(ethanol)∶V(H2 O)=1 solution to get HPEG/PAA.%采用原子转移自由基聚合(ATRP )法聚合甲基烯丙基聚氧乙烯醚(HPEG)和丙烯酸甲酯(PMA),生成低分子量梳形结构的低聚物 HPEG/PMA.经Fourier红外光谱(FT-IR)和核磁共振氢谱(1 H NMR)对其结构特征基团进行分析,确认合成了目标产物.对 HPEG/PMA进行凝胶渗透色谱(GPC)测试,结果表明,ATRP 法制备的梳形 HPEG/PMA分子量为7.7×103,分布系数为1.11,具有优异的可控性.梳形HPEG/PMA经V(乙醇)∶V(水)=1的NaOH溶液水解,得到梳形结构甲基烯丙基聚氧乙烯醚和丙烯酸(HPEG/PAA)低聚物.

  3. Polymer Molecular Architecture As a Tool for Controlling the Rheological Properties of Aqueous Polyacrylamide Solutions for Enhanced Oil Recovery

    NARCIS (Netherlands)

    Wever, Diego A. Z.; Polgar, Lorenzo M.; Stuart, Marc C. A.; Picchioni, Francesco; Broekhuis, Antonius A.

    2013-01-01

    The controlled synthesis of high molecular weight branched polyacrylamide (PAM) has been accomplished by using atomic transfer radical polymerization (ATRP) of acrylamide (AM) in water at room temperature. Halogen-functionalized aliphatic polyketones acted as macroinitiators in the polymerization. T

  4. SYNTHESIS AND CHARACTERIZATION OF FOUR-ARMED BLOCK POLY(STYRENE-b-p-NITRO PHENYL METHACRYLATE) PREPARED BY THE ATRP METHOD

    Institute of Scientific and Technical Information of China (English)

    Cai-yuan Pan; Lei Tao; Ye Liu

    2002-01-01

    A novel tetrafunctional initiator, C[CH2O(CH2)3OOCCH(Br)CH3]4 (1), was synthesized through the reaction oftetraol with α-bromopropionyl chloride, and then was used as initiator of atom transfer radical polymerization (ATRP) in thepreparation of 4-armed polystyrene (PSt) with narrow polydispersity. The structure, molecular weight and molecular weightdistribution (MWD) of each arm were studied by 1H-NMR and GPC data of hydrolyzed products of the 4-armed PSt. TheATRP of St using 1/CuBr/bpy as initiator system is of "living" character based on the following evidence: narrow MWD,constant concentration of chain radical during the polymerization, control of molecular weight by the molar ratio of monomerconsumed to 1. The 4-armed poly(St-b-p-nitrophenyl methacrylate) [poly(St-b-NPMA)] was prepared by the ATRP ofNPMA using 4-armed PSt with terminal bromine as the initiator, and characterized by FT-IR, 1H-NMR spectra and GPCcurves. The micelles with PSt as core, and PNPMA as shell were formed by dropping DMSO into a solution of 4-armedpoly(St-b-NPMA) in DMF, as proved by laser light scatter (LLS) method.

  5. Surface Immobilization of pH-Responsive Polymer Brushes on Mesoporous Silica Nanoparticles by Enzyme Mimetic Catalytic ATRP for Controlled Cargo Release

    Directory of Open Access Journals (Sweden)

    Hang Zhou

    2016-08-01

    Full Text Available Peroxidase mimetic catalytic atom transfer radical polymerization (ATRP was first used to install tertiary amine-functionalized polymer brushes on the surface of mesoporous silica nanoparticles (MSNs in a facile and highly efficient manner. Poly(N,N-dimethylaminoethyl methacrylate (PDMAEMA brushes-grafted MSNs were fabricated by biocompatible deuterohemin-β-Ala-His-Thr-Val-Glu-Lys (DhHP-6-catalyzed surface-initiated ATRP (SI-ATRP. The resulting organic–inorganic hybrid nanocarriers were fully characterized by Fourier transform-infrared spectroscopy (FT-IR, thermogravimetric analysis (TGA, X-ray photoelectron spectroscopy (XPS, powder X-ray diffraction (XRD, SEM, TEM, Elemental analysis, Zeta-potential, and N2 adsorption–desorption isotherms, which demonstrated the successful coating of pH-responsive polymers on the MSN surface. Rhodamine 6G (Rh6G dyes were further loaded within the mesopores of this nanocarrier, and the release of Rh6G out of MSNs in a controlled fashion was achieved upon lowing the solution pH. The electrostatic repulsion of positively-charged tertiary ammonium of PDMAEMAs in acidic environments induced the stretching out of polymer brushes on MSN surfaces, thus opening the gates to allow cargo diffusion out of the mesopores of MSNs.

  6. Blood compatibility comparison for polysulfone membranes modified by grafting block and random zwitterionic copolymers via surface-initiated ATRP.

    Science.gov (United States)

    Xiang, Tao; Zhang, Li-Sha; Wang, Rui; Xia, Yi; Su, Bai-Hai; Zhao, Chang-Sheng

    2014-10-15

    For blood-contacting materials, good blood compatibility, especially good anticoagulant property is of great importance. Zwitterionic polymers have been proved to be resistant to nonspecific protein adsorption and platelet adhesion; however, their anticoagulant property is always inadequate. In this study, two kinds of zwitterionic copolymers (sulfobetaine methacrylate and sodium p-styrene sulfonate random copolymer and block copolymer) with sulfonic groups were covalently grafted from polysulfone (PSf) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) to improve blood compatibility. Field emission scanning electron microscopy (FE-SEM), attenuated total reflectance-Fourier transform infrared spectra (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and static water contact angle (WCA) were applied to characterize the morphologies, chemical compositions and hydrophilicity of the modified membranes. All the zwitterionic copolymer modified membranes showed improved blood compatibility, especially the anticoagulant property was obviously enhanced compared to the pristine PSf and simple zwitterionic polymer modified membranes. We also found that the random copolymer modified membranes showed better resistance to platelet adhesion than the block copolymer modified membranes. The zwitterionic copolymer modified membranes with integrated antifouling property and blood compatibility provided wide choice for specific applications such as hemodialysis, hemofiltration, and plasma separation.

  7. Fabrication and evaluation of temperature responsive molecularly imprinted sorbents based on surface of yeast via surface-initiated AGET ATRP

    Science.gov (United States)

    Pan, Jianming; Hang, Hui; Li, Xiuxiu; Zhu, Wenjing; Meng, Minjia; Dai, Xiaohui; Dai, Jiangdong; Yan, Yongsheng

    2013-12-01

    Temperature responsive molecularly imprinted polymers (T-MIPs) were prepared based on the surface of yeast by electron transfer atom transfer radical polymerization (AGET ATRP). The as-prepared T-MIPs were charcterized by FT-IR, SEM, TGA and elemental analysis, which indicated that T-MIPs exhibited thermal stability and composed of temperature responsive imprinted layer. Then T-MIPs were evaluated as sorbents to selectively recognise and release cefalexin (CFX) molecules. The results suggested binding properties of T-MIPs were related to the testing temperature. The maximum adsorption capacity of T-MIPs at 303 K was 59.4 mg g-1, and the maximum release proportion for T-MIPs at 293 K in water for 24 h was 71.08%. The selective recognition experiments demonstrated high affinity and selectivity of T-MIPs towards CFX over competitive compounds, and the specific recognition of binding sites may be based on the distinct size, structure and functional group to the template molecules.

  8. Synthesis and molecular structure of 2-bromo-N-(4-(7-(diethylamino)-coumarin-3-yl)phenyl)propanamide: New coumarin-based fluorescent ATRP initiator

    Science.gov (United States)

    Kulai, Ihor; Mallet-Ladeira, Sonia

    2016-01-01

    The 2-bromo-N-(4-(7-(diethylamino)-coumarin-3-yl)phenyl)propanamide was synthesized and analyzed by NMR and FT-IR spectroscopies, high resolution mass-spectrometry and single crystal X-ray diffraction. The crystal structure belongs to the monoclinic system, P21/c space group with a = 14.9120(7) Å, b = 11.3177(5) Å, c = 12.0106(5) Å, α = 90°, β = 94.758(2)°, γ = 90° and V = 2020.04(16) Å3. Furthermore, it was shown to be an efficient fluorescent ATRP initiator in polymerizations of acrylates.

  9. Synthesis of well-defined functional PE graft copolymers via ATRP process

    Institute of Scientific and Technical Information of China (English)

    CAO Chengang; DONG Jinyong; HU Youliang

    2005-01-01

    @@ Polyethylene (PE) is one of the most important polymeric materials. It has excellent physical mechanical properties and thus a widespread range of applications. However, due to the lack of polar functional groups on its polymer chain, PE usually suffers from poor adhesion to and incompatibility with other polymers or materials, which has significantly limited many of its end uses. To resolve this problem, one of the established approaches is to introduce a second functional polymeric component as side chains to synthesize PE graft copolymers that not only provide a large quantity of functional groups to impart polarity to PE but also preserve the original desired PE properties, such as crystallinity, melting point, and hydrophobicity[1].

  10. Immobilization of poly(acrylamide) brushes onto poly(caprolactone) surface by combining ATRP and “click” chemistry: Synthesis, characterization and evaluation of protein adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yuhao; Bian, Xinxiu; He, Liu; Cai, Mengtan; Xie, Xiaoxiong [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Luo, Xianglin, E-mail: luoxl@scu.edu.cn [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); State Key Laboratory of Polymer Material and Engineering, Sichuan University, Chengdu 610065 (China)

    2015-02-28

    Highlights: • Poly(caprolacone) (PCL) film surface was chemically modified by a novel method through combining ATRP and “click” chemistry. • Poly(acrylamide) (PAAm) of tailored chain length were synthesized and “clicked” onto PCL surface. • The modified PCL surface showed reduced BSA and Fg adsorption, and the protein resist ability in terms of chain length through its impact on grafting reaction and modified surface was investigated. - Abstract: Developments of poly(caprolactone) in blood-contacting applications are often restricted due to its intrinsic hydrophobicity. One common way to improve its hemocompatibility is to attach hydrophilic polymers. Here we developed a non-destructive method to graft hydrophilic poly(acrylamide) (PAAm) onto poly(caprolactone) (PCL) surface. In this strategy, azido-ended PCL with low molecular weights was synthesized and blended with PCL to create a surface with “clickable” property. Alkyne-ended poly(acrylamide)s with controlled chain lengths were then synthesized by atom transfer radical polymerization (ATRP), and finally were immobilized onto PCL surface by “click” reaction. The occurrence of immobilization was verified qualitatively by water contact angle measurement and quantitatively by X-ray photoelectron spectroscopy (XPS). The PAAm grafted surface exhibited fouling resistant properties, as demonstrated by reduced bovine serum albumin (BSA) and fibrinogen (Fg) adhesion.

  11. Amphiphilic star block copolymers as gene carrier Part I: Synthesis via ATRP using calix[4]resorcinarene-based initiators and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Anna; Xue, Yan; Wei, Dafu [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Guan, Yong, E-mail: yguan@ecust.edu.cn [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Xiao, Huining [Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 (Canada)

    2013-01-01

    In this work, a cationic star polymer [poly(2-dimethylamino)ethyl methacrylate (PDMAEMA)] was prepared via atom transfer radical polymerization (ATRP), using brominated calix[4]resorcinarene as an initiator. Hydrophobic moieties, methyl methacrylate (MMA) and butyl acrylate (BA), were further incorporated via 'one-pot' method. Well-defined eight-armed star block copolymers bearing hydrophilic blocks inside and hydrophobic blocks outside were synthesized. The molecular weight, particle size, electrophoretic mobility and apparent charge density were determined by gel permeation chromatography (GPC), dynamic light scattering (DLS), phase analysis light scattering (PALS) and colloidal titration, respectively. The zeta potentials and apparent charge densities of the products exhibited the characteristics of polyelectrolyte. The incorporation of hydrophobic moieties generated electrostatic screening effect. The as-synthesized amphiphilic star copolymer is promising as a thermo-sensitive gene carrier for gene therapy. Highlights: Black-Right-Pointing-Pointer Amphiphilic cationic star block copolymers with well-controlled structures were prepared via ATRP. Black-Right-Pointing-Pointer The molecular structures and properties of the initiator and copolymers were systematically characterized. Black-Right-Pointing-Pointer The products exhibited the positive charged character, and hydrophobic moieties generated electrostatic screening effect.

  12. Immobilization of poly(acrylamide) brushes onto poly(caprolactone) surface by combining ATRP and "click" chemistry: Synthesis, characterization and evaluation of protein adhesion

    Science.gov (United States)

    Ma, Yuhao; Bian, Xinxiu; He, Liu; Cai, Mengtan; Xie, Xiaoxiong; Luo, Xianglin

    2015-02-01

    Developments of poly(caprolactone) in blood-contacting applications are often restricted due to its intrinsic hydrophobicity. One common way to improve its hemocompatibility is to attach hydrophilic polymers. Here we developed a non-destructive method to graft hydrophilic poly(acrylamide) (PAAm) onto poly(caprolactone) (PCL) surface. In this strategy, azido-ended PCL with low molecular weights was synthesized and blended with PCL to create a surface with "clickable" property. Alkyne-ended poly(acrylamide)s with controlled chain lengths were then synthesized by atom transfer radical polymerization (ATRP), and finally were immobilized onto PCL surface by "click" reaction. The occurrence of immobilization was verified qualitatively by water contact angle measurement and quantitatively by X-ray photoelectron spectroscopy (XPS). The PAAm grafted surface exhibited fouling resistant properties, as demonstrated by reduced bovine serum albumin (BSA) and fibrinogen (Fg) adhesion.

  13. The effect of hydrophilic and hydrophobic block length on the rheology of amphiphilic diblock Polystyrene-b-Poly(sodium methacrylate) copolymers prepared by ATRP.

    Science.gov (United States)

    Raffa, Patrizio; Stuart, Marc C A; Broekhuis, Antonius A; Picchioni, Francesco

    2014-08-15

    Following our previous investigation on the effect of molecular architecture on the rheology of Polystyrene-b-Poly(sodium methacrylate) copolymers (PS-b-PMAA), we consider here diblock PS-b-PMAA copolymers characterized by a different length of either the hydrophilic or the hydrophobic block. Various copolymers characterized by different PS or PMAA block length have been prepared by ATRP (kinetics is also discussed) and studied from the point of view of their rheological behaviour in water. To the best of our knowledge, this is the first systematic investigation concerning the effect of block length on the rheology of diblock polyelectrolytes. We found that the hydrophobic block length has small influence on the rheology. Surprisingly, the polymers with shortest PMAA blocks yield the strongest gels at high concentration. A simple model based on the classical theories of self-assembly and percolation of amphiphilic polymers has been here developed in order to explain the observed data.

  14. Immobilization of poly(MPC) brushes onto titanium surface by combining dopamine self-polymerization and ATRP: Preparation, characterization and evaluation of hemocompatibility in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Wenyong; Yang, Ping; Li, Jingan; Li, Shiqi; Li, Peichuang; Zhao, Yuancong, E-mail: Zhaoyc7320@163.com; Huang, Nan

    2015-09-15

    Graphical abstract: The functional surface containing rich amino and hydroxyl groups was obtained by simple and easily dopamine self-polymerization. Poly (MPC) brushes were successfully immobilized on titanium surface by combining acylation reaction and ATRP. This chemical and biomimetic modified titanium surface effectively inhibits platelet adhesion and activation. - Highlights: • Polydopamine coating provides amino and hydroxyl groups for second reactivity. • Poly(MPC) brushes covalently immobilized on coating by surface initiated ATRP. • In vitro hemocompatibility of biomimetic modified Ti was better than unmodified. - Abstract: Poly(2-methacryloyloxyethyl phosphorylcholine(MPC)) has been studied in many biomedical fields because of good biocompatibility, such as hemocompatibility, inhibiting protein adhesion, antifouling, and so on. To achieve good hemocompatibility of titanium (Ti) surface, bio-inspired poly(MPC) brushes were grafted from Ti substrate covalently. In this work, the surface of Ti was first coated with polydopamine, and got a surface bearing −NH{sub 2} and −OH groups which could be bridged with poly(MPC) via atom transfer radical polymerization. Water contact angle decreased to 51.3° when titanium grafted with poly(MPC) brushes. The data of Infrared Spectroscopy and X-ray photoelectron spectroscopy (XPS) indicated that poly(MPC) was successfully grafted onto the surface of titanium. Platelet-rich plasma (PRP) adhesion test and lactate dehydrogenase (LDH) assay showed that the number of platelets adhered on the surface of modified-titanium was much less than that of unmodified titanium and platelets did not aggregate and distort. Thus, the simple and chemical method of immobilization of poly(MPC) brushes has potential application for improving hemocompatibility for cardiovascular stent and some other biomaterials.

  15. 离子液体中采用AGET ATRP法制备MCC-g-PGMA%Synthesis of MCC-g-PGMA by AGET ATRP in ionic liquids

    Institute of Scientific and Technical Information of China (English)

    袁淼; 唐二军; 杜凯迪; 刘洪; 周剑; 刘少杰; 赵地顺

    2015-01-01

    在氯化1-烯丙基-3-甲基咪唑([AMIM]Cl)离子液体中,采用AGET ATRP技术,以VC为还原剂、CuBr2/乙二胺为催化体系,成功制备了微晶纤维素接枝聚甲基丙烯酸缩水甘油酯(MCC-g-PGMA)分子.研究表明:[AMIM]Cl对微晶纤维素有较好的溶解性,最佳反应条件为GMA/乙二胺/CuBr2/VC摩尔比为100:4:1:1,反应温度25℃,反应时间4 h,接枝效率可达54.56%,分子量分布较窄为1.48.通过FT-IR、TEM和SEM测试表明:成功合成了MCC-g-PGMA接枝共聚物分子,PGMA接枝微晶纤维素后表面形态变得粗糙,接枝共聚物在丙酮溶液中可自组装成150~200 nm的球形结构,在药物载体领域具有良好的应用潜能.%The MCC-g-PGMA was synthesized by AGET ATRP in ionic liquid [AMIM]Cl. Vitamin C was used as the reducing agent and CuBr2/ethanediamine was the catalytic system. The experiment proved that microcrystalline cellulose can well dissolve in [AMIM]Cl. Optimum mole ratio of GMA/ethanediamine/ CuBr2/VC were attained at 100:4:1:1. The temperature and reaction time were 25℃ and 4 h. The grafting efficiency was as high as 54.56% and the distribution of molecular weight of MCC-g-PGMA was 1.48. FT-IR proved that the MCC-g-PGMA graft copolymer was successfully synthesized by AGET ATRP in [AMIM]Cl. SEM showed the surface of MCC was changed and became coarse after PGMA grafted to MCC. It has a perfect application potential in the field of drug carrier.

  16. Surface functionalization of graphene oxide with poly(2-hydroxyethyl methacrylate)- graft-poly(ɛ-caprolactone) and its electrospun nanofibers with gelatin

    Science.gov (United States)

    Massoumi, Bakhshali; Ghandomi, Fereshteh; Abbasian, Mojtaba; Eskandani, Morteza; Jaymand, Mehdi

    2016-12-01

    This article describes covalent functionalization of graphene oxide (GO) with poly(2-hydroxyethyl methacrylate)- graft-poly(ɛ-caprolactone) [P(HEMA- g-CL)] via `living' polymerization techniques and preparation of its electrospun nanofibers with gelatin. For this purpose, the GO was synthesized by oxidizing pristine graphite powder and then acetyl chloride was incorporated into the GO to afford an atom transfer radical polymerization (ATRP) macroinitiator (GO-Cl). The synthesized macroinitiator was employed for HEMA polymerization via ATRP technique to produce GO- g-PHEMA. Afterward, CL was graft copolymerized from the hydroxyl groups of the PHEMA via ring-opening polymerization approach to afford GO- g-[P(HEMA- g-CL)] nanocomposite. The solutions of the GO- g-[P(HEMA- g-CL)] and gelatin were electrospun to fabricate uniform, conductive, and biocompatible nanofibers. The morphology, in vitro degradability, biocompatibility, hydrophilicity, and conductivity of the GO- g-[P(HEMA- g-CL)]/gelatin electrospun nanofibers were investigated. It is expected that the prepared nanofibers find application as a scaffolding biomaterial for regenerative medicine, mainly due to their biocompatibility, degradability, and electrical conductivity.

  17. Remarkable pH-responsive polypropylene microfiltration membrane through surface entrapment of poly(2-(diethylamino) ethyl methacrylate)-containing macromolecules by ATRP method.

    Science.gov (United States)

    Jiang, Ping; Li, Duxin; Liu, Yuejun; Zhang, Xiuju; Lai, Dengwang

    2013-03-01

    Polypropylene (PP) microfiltration membrane were functionalized with an adsorption/surface entrapment process, using block copolymers with poly(n-butyl acrylate) (PBA) as anchor block being capable to tether the pH-responsive block poly(2-(diethylamino) ethyl methacrylate) (PDEA) to the surface, Homopolymer and Block copolymer synthesis was investigated by atom transfer radical polymerization (ATRP) using PMDETA, CuBr and ethyl acetate. These polymers were characterized by 1H NMR and GPC. Copolymer of PDEA with polybutylacrylate (PBA) was selected as best suitable modifier. Models related to the underlying deswelling/entrapment process which leads to fixation of the modifier were considered. Surface properties were analyzed by ATR-FTIR spectroscopy and water contact angle measurements, which confirmed the presence of modifier and a strong improvement of surface and pore wettability. The structure of membranes was evaluated using Polarized Optical Microscopy. Furthermore the pH-sensitive properties of modified PP membranes were verified by pH-dependence of water permeability which due to protonation/deprotonation and volume phase transition of PDEA around the pH 6-6.9.

  18. AS1411 aptamer and folic acid functionalized pH-responsive ATRP fabricated pPEGMA-PCL-pPEGMA polymeric nanoparticles for targeted drug delivery in cancer therapy.

    Science.gov (United States)

    Lale, Shantanu V; R G, Aswathy; Aravind, Athulya; Kumar, D Sakthi; Koul, Veena

    2014-05-12

    Nonspecificity and cardiotoxicity are the primary limitations of current doxorubicin chemotherapy. To minimize side effects and to enhance bioavailability of doxorubicin to cancer cells, a dual-targeted pH-sensitive biocompatible polymeric nanosystem was designed and developed. An ATRP-based biodegradable triblock copolymer, poly(poly(ethylene glycol) methacrylate)-poly(caprolactone)-poly(poly(ethylene glycol) methacrylate) (pPEGMA-PCL-pPEGMA), conjugated with doxorubicin via an acid-labile hydrazone bond was synthesized and characterized. Dual targeting was achieved by attaching folic acid and the AS1411 aptamer through EDC-NHS coupling. Nanoparticles of the functionalized triblock copolymer were prepared using the nanoprecipitation method, resulting in an average particle size of ∼140 nm. The biocompatibility of the nanoparticles was evaluated using MTT cytotoxicity assays, blood compatibility studies, and protein adsorption studies. In vitro drug release studies showed a higher cumulative doxorubicin release at pH 5.0 (∼70%) compared to pH 7.4 (∼25%) owing to the presence of the acid-sensitive hydrazone linkage. Dual targeting with folate and the AS1411 aptamer increased the cancer-targeting efficiency of the nanoparticles, resulting in enhanced cellular uptake (10- and 100-fold increase in uptake compared to single-targeted NPs and non-targeted NPs, respectively) and a higher payload of doxorubicin in epithelial cancer cell lines (MCF-7 and PANC-1), with subsequent higher apoptosis, whereas a normal (noncancerous) cell line (L929) was spared from the adverse effects of doxorubicin. The results indicate that the dual-targeted pH-sensitive biocompatible polymeric nanosystem can act as a potential drug delivery vehicle against various epithelial cancers such as those of the breast, ovary, pancreas, lung, and others.

  19. Synthesis of block copolymers derived from N-trityl-(S)-serine and pyrene end-labeled poly(methyl methacrylate) or poly(N-isopropylacrylamide) via ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Buruiana, Emil C., E-mail: emilbur@icmpp.ro [Petru Poni Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley 700487, Iasi (Romania); Podasca, Viorica; Buruiana, Tinca [Petru Poni Institute of Macromolecular Chemistry, 41A Gr. Ghica Voda Alley 700487, Iasi (Romania)

    2012-10-15

    A new monomer bearing N-trityl-L-serine methyl ester in structure, methacryloyloxyethyl carbamoyloxy-N-trityl methyl serine (MTS), was prepared to be further polymerized by atom transfer radical polymerization (ATRP) with pyrene-endcapped poly(methyl methacrylate) (Py-PMMA-Br) or poly(N-isopropylacrylamide) (Py-PNIPA-Br). The resulting block copolymers, poly(methyl methacrylate-block-methacryloyloxyethyl carbamoyloxy-N-trityl methyl serine) (Py-PMMA-b-PMTS) and poly(N-isopropylacrylamide-block-methacryloyloxyethyl carbamoyloxy-N-trityl methyl serine (Py-PNIPA-b-PMTS) were characterized by {sup 1}H ({sup 13}C) NMR, ultraviolet, FTIR and fluorescence spectroscopy, thermal analysis, differential scanning calorimetry (DSC), atomic force microscopy (AFM), scanning electron microscopy (SEM), and gel permeation chromatography (GPC) measurements. The chemical composition in Py-PMMA-b-PMTS was estimated from the {sup 1}H NMR analysis that indicated a ratio of the repeating units of 46:19 (MMA:MTS). For the Py-PNIPA-b-PMTS the composition rate in the copolymer was 61:25 (NIPA:MTS). Quenching of the pyrene species with N,N-diethylaniline, nitrobenzene, nitrophenol, potassium iodide, p-nitrotoluene and tetracyanoquinodimethane (TCNQ) in DMF solution excited at 348 nm was evidenced, more efficiently being nitrophenol and TCNQ. In this case, the monomer emission at 388-409 nm underwent a significant decrease caused of an electron transfer from the electron-reach photoexcited pyrene molecule to the electron-deficient quenchers. - Highlights: Black-Right-Pointing-Pointer Diblock copolymers combine the fluorescence of pyrene-PMMA (PNIPA) with the characteristics of PMTS. Black-Right-Pointing-Pointer Such copolymers could be used for nitroderivatives detecting. Black-Right-Pointing-Pointer UV/vis and fluorescence measurements give a good correlation for LCST of Py-PNIPA-Br.

  20. EFFECT OF MOLECULAR WEIGHT OF MACRO-INITIATOR ON ELECTRO-OPTICAL PROPERTIES OF POLYMER DISPERSED LIQUID CRYSTAL BASED ON GRAFT POLYMERS%大分子引发剂分子量对接枝聚合物基体的PDLC电光性能的影响

    Institute of Scientific and Technical Information of China (English)

    张玉良; 秦爱林; 汪映寒

    2012-01-01

    以可逆加成-断裂链转移(RAFT)、引发转移终止(iniferter)活性自由基聚合相结合的方法,用一步法制备了不同分子量的大分子引发剂RAFT-PS-co-PCMSI(MI),并通过紫外光聚合诱导相分离法制备了以接枝聚合物为基体的聚合物分散液晶(PDLC)膜.研究了不同分子量的MI对PDLC的微观形貌,关闭状态透光率,阈值电压,饱和电压以及记忆效应等方面的影响.研究表明,降低PDLC中MI的分子量,会使得液晶微滴粒径增大,阈值电压(Vth)、饱和电压(V(ast))减小,记忆效应、关闭状态透光率升高.%Polymer dispersed liquid crystal ( PDLC) films were prepared by photopolymerization induced phase separation (PIPS) with living macro-initiator (MI) of different molecular weights,synthesized by RAFT and iniferter polymerization. The effect of molecular weight of Mis on electro-optical properties of PDLC based on graft polymers was investigated. The effects of molecular weight of Mis on morphologies, transmittance, switching voltage and memory effect of PDLC films were studied in detail. It was found that the decrease in the molecular weight of Mis in the films led to the formation of larger liquid crystal droplets. The threshold voltage decreased from 15. 9 V to 4. 2 V and the off-state transmittance showed an increase tendency,which could be contributed to the increase of liquid crystal droplet diameter. In addition, the saturation voltage also decreased from 36. 5 V to 16. 4 V while the memory effect increased because of the decreased interface anchoring strength induced by the lower molecular weight of polymer matrix and weaker entanglement that polymer flexible main chain exerted on liquid crystal molecules. Therefore, the decrease decrease of molecular weight of Mis successfully improved the electro-optical properties of PDLC films based on graft polymers.

  1. Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)- co -chlorinated Poly(vinyl chloride) (PVC- co -CPVC) Fiber

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Suree; Yue, Yanfeng; Kuo, Li-Jung; Mehio, Nada; Li, Meijun; Gill, Gary; Tsouris, Costas; Mayes, Richard T.; Saito, Tomonori; Dai, Sheng

    2016-04-20

    The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly- (vinyl chloride)-co-chlorinated poly(vinyl chloride) (PVC-co-CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert-butyl acrylate (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-binding ligands (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in natural seawater tests (2.42-3.24 g/kg in 42 days of seawater exposure and 5.22 g/kg in 49 days of seawater exposure, versus 1.66 g/kg in 42 days of seawater exposure and 1.71 g/kg in 49 days of seawater exposure for JAEA). Adsorption of other metal ions from seawater and their corresponding kinetics were also studied. The grafting of alternative monomers for the recovery of uranium from seawater is now under development by this versatile technique of ATRP.

  2. Synthesis and characterization of a novel acryl amide-based yttrium imprinted sorbent via the ATRP approach for the preparation of medical-grade {sup 90}Y

    Energy Technology Data Exchange (ETDEWEB)

    Abedi, Mahvash [Nuclear Schience and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of); Shahid Beheshti Univ., Tehran (Iran, Islamic Republic of). Dept. of Chemistry; Shirvani-Arani, Simindokht; Bahrami-Samani, Ali [Nuclear Schience and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of); Nabid, Mohammad Reza [Shahid Beheshti Univ., Tehran (Iran, Islamic Republic of). Dept. of Chemistry

    2016-05-01

    Because of its favorable radionuclidic properties (pure beta emitter, E{sub βmax} = 2.28 MeV, T{sub 1/2} = 64.1 h), the preparation of carrier free {sup 90}Y is of a great importance in radiopharmacy. Herein, we report the synthesis, characterization, and application of a novel yttrium sorbent prepared on the basis of the ion-imprinting concept. The ion-imprinted polymer (IIP) was prepared by atom transfer radical copolymerization of acryl amide (AAm, functional monomer) and N,N'-methylenebisacrylamide (MBAAm) crosslinking agent in the presence of a complex of yttrium ions (template ions) with a homemade chelator, i.e., 2,2-bis(2-bromo-2-methylpropanoate)propane-1,3-disuccinate (also as initiator). For elimination of yttrium ions, which act as the template, the prepared particles were treated with 50% v:v HCl: H{sub 2}O to produce yttrium-imprinted polymeric sorbent. To control the imprinting effect, corresponding non-imprinted particles (NIP) were prepared in a similar manner except that yttrium ions were not used. The synthesized chemicals for the preparation of the chelator-initiator compound and the product itself were assessed in every step using {sup 1}H-NMR analysis. NIP and YIP were subjected to X-ray diffraction (XRD), infra-red spectroscopy (IR) and BET surface area analysis for characterization studies. Sorption/desorption studies were conducted, and the effects of potentially interfering ions, such as Sr{sup 2+} (α = 119.69) and Zr{sup 4+} (α = 73.01) in presence of radio-yttrium, were investigated (particle size: 50-100 μm, resultant recovery of > 99% within 60 min and a capacity of 33.33 mg Y(III) per gram of sorbent). The results showed that amounts of radio-yttrium as low as 250 μg could be extracted effectively with high radionuclidic and radiochemical purity from macro-gram amounts of strontium.

  3. Double-bond-containing polyallene-based triblock copolymers via phenoxyallene and (meth)acrylate

    Science.gov (United States)

    Ding, Aishun; Lu, Guolin; Guo, Hao; Huang, Xiaoyu

    2017-03-01

    A series of ABA triblock copolymers, consisting of double-bond-containing poly(phenoxyallene) (PPOA), poly(methyl methacrylate) (PMMA), or poly(butyl acrylate) (PBA) segments, were synthesized by sequential free radical polymerization and atom transfer radical polymerization (ATRP). A new bifunctional initiator bearing azo and halogen-containing ATRP initiating groups was first prepared followed by initiating conventional free radical homopolymerization of phenoxyallene with cumulated double bond to give a PPOA-based macroinitiator with ATRP initiating groups at both ends. Next, PMMA-b-PPOA-b-PMMA and PBA-b-PPOA-b-PBA triblock copolymers were synthesized by ATRP of methyl methacrylate and n-butyl acrylate initiated by the PPOA-based macroinitiator through the site transformation strategy. These double-bond-containing triblock copolymers are stable under UV irradiation and free radical circumstances.

  4. Preparation of photoresponse azobenzene polymer by ATRP%原子转移自由基聚合法制备偶氮苯聚合物

    Institute of Scientific and Technical Information of China (English)

    刘长玲; 王怀宇; 宋岩

    2016-01-01

    偶氮苯类聚合物具有光响应性,在信息储存、光电子、分子开关等领域得到了很好的应用。采用原子转移自由基聚合法,以三羟甲基丙烷为核制备引发剂,以偶氮苯为单体合成三臂聚偶氮苯星形聚合物。通过红外光谱仪、核磁共振氢谱仪对聚合物的结构进行表征,结果表明已成功地合成出目标产物。通过GPC(凝胶渗透色谱仪)对其相对分子质量及其分布进行测试,表明合成出的聚合物符合“活性-可控”聚合特征。利用紫外-可见分光光度计测定聚偶氮苯的紫外吸收,结果表明具有光照射下的构型反转。%Azobenzene polymers have photoresponsive property and get very good application in fields of information storage, photonics, molecular switch etc. The azobenzene star polymer with three- arm was pre⁃pared by atom transfer radical polymerization (ATRP), using the trimethyolpropane as the initiator of nuclear preparation, and azobenzene as the monomer. The structure of polymers were characterized by the infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance spectrometer (1H- NMR), which showed that the target product was successful y synthesized. The molecular weight and the molecular weight distribution of the polymer was measured by gel permeation chromatograph (GPC), and the results showed that the synthe⁃sized polymer agreed with the "reactive- control able" characteristics. The result of UV spectrophotometer ab⁃sorption of polyazobenzene showed the configuration inversion under light radiation.

  5. Controlled synthesis of cellulose grafting PDEAEMA brushes by ATRP in ionic liquid [AMIM]Cl%[AMIM]Cl离子液体中纤维素接枝PDEAEMA分子刷的均相可控聚合

    Institute of Scientific and Technical Information of China (English)

    杜凯迪; 唐二军; 袁淼; 刘少杰; 赵地顺

    2015-01-01

    The microcrystalline cellulose-g-poly[2-(diethylamino)ethyl methacrylate] (MCC-g-PDEAEMA) polymer brushes were synthesized under control by atom transfer radical polymerization (ATRP) in the ionic liquid 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). Ethyl alcohol was used as the cosolvent to form a homogeneous system and solve the problem that the functional monomerN,N-diethylamino-2-ethyl methacrylate (DEAEMA) hardly dissolved in [AMIM]Cl. The synthetic mechanism of heterogeneous system and homogeneous system in [AMIM]Cl was analyzed. The experiments showed that the byproduct PDEAEMA in the homogeneous system was reduced and the grafting efficiency of the polymer brushes was improved. Meanwhile, the molecular weight distribution was narrow and ATRP was easily controlled. Optimum reaction conditions in the homogeneous system were attained at CuBr/PMDETA/DEAEMA/ethyl alcohol molar ratio of 1:15:150:300. The grafting efficiency could reach to 78.1%. MCC-g-PDEAEMA was characterized through FTIR spectroscopy,1H NMR spectroscopy and GPC. The results proved that the PDEAEMA side chains were covalently bonded to the MCC backbone and the molecular weight distribution of the polymer brushes were even.%在氯化1-烯丙基-3-甲基咪唑([AMIM]Cl)离子液体中,采用原子转移自由基(ATRP)法接枝改性微晶纤维素,合成了微晶纤维素-g-甲基丙烯酸二乙氨基乙酯(MCC-g-PDEAEMA)聚合物分子刷。通过加入助溶剂形成均相反应体系,解决了功能性单体甲基丙烯酸二乙氨基乙酯(DEAEMA)在[AMIM]Cl离子液体中的溶解问题。分别研究了离子液体中均相与非均相的反应机理,结果表明:在均相体系中,生成的反应副产物PDEAEMA较少,聚合物分子刷的接枝效率较高,分子量分布窄,ATRP 反应可控性好。实验确定了均相体系最佳反应条件:CuBr/PMDETA/ DEAEMA/乙醇的摩尔比为1:15:150:300, MCC-g-PDEAEMA的接枝效率可达78.1%。通过

  6. Preparation and characterization of poly(glycidyl methacrylate)-grafted magnetic nanoparticles: Effects of the precursor concentration on polyol synthesis of Fe3O4 and [PMDETA]0/[CuBr2]0 ratios on SI-AGET ATRP

    Science.gov (United States)

    Jiang, Liping; Zhou, Xuyang; Wei, Guyun; Lu, Xiaoduo; Wei, Weiping; Qiu, Jianhua

    2015-12-01

    Polymer brushes based on poly(glycidyl methacrylate) (PGMA) have been successfully grafted from the surface of silica coated iron oxide (Fe3O4@SiO2) nanoparticles via surface-initiated activators generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The size of the nanoparticles could be adjusted from 7.3 to 9.6 nm by varying the precursor concentration of iron(III) acetylacetonate. The Fe3O4 nanoparticles possessed a highly crystalline structure, and the saturation magnetization of the as-prepared magnetite was strongly related to the particle size. Furthermore, the grafted PGMA content on the magnetic nanoparticles could be controlled by varying the ligand to transition metal ratio in a N,N,N‧,N″,N″-pentamethyldiethylenetriamine (PMDETA)/CuBr2 catalyst system. The maximum grafted content was 23.1% at a ratio of [PMDETA]0/[CuBr2]0 = 2:1.

  7. “活”的α-甲基苯乙烯共聚物:聚合反应新化学和材料工程新技术%A Novel Macroinitiator Based on the Copolymer of α-Methylstyrene Synthesis and Its Application in Preparing Block and Graft Polymers

    Institute of Scientific and Technical Information of China (English)

    马育红; 张冰; 赵长稳; 刘莲英; 蒋姗; 梁淑君; 杨万泰

    2013-01-01

    Due to the steric hindrance effects in combination with stability of the tertiary benzylic a-methylstyryl radical, there is a dynamic equilibrium between the monomer a-methylstyrene (AMS) and its polymer (PAMS) when the temperature is greater than 61 ℃ (the ceiling polymerization temperature). Based on this unique feature, a novel strategy to prepare co-polymers of AMS having liable bonds as potential macromolecular free radical initiators for synthesizing block and graft copolymers has been successfully developed in our laboratory. By conventional free radical polymerization, a series of AMS copolymers, including copolymers with (meth)acrylate, acrylic acid, styrene and maleic anhydride were synthesized. Typically, with the increasing of AMS fraction in monomer feed, the rate of copolymerization was significantly retarded and the molecular weight of the copolymers was reduced. However, the copolymer yield could be as high as 90% (w) with the increased addition of initiator, up to 4% (w), and the molar fraction of AMS structural unit in AMS copolymers could be up to 25% (mol%). It has been demonstrated that the copolymers containing AMS structural units are efficient free radical initiators when the temperature is greater than 80 ℃ (much better higher than 90 ℃). These copolymers could be exploited as macroinitiator in preparing block copolymers and core-shell polymer particles by bulk, solution and emulsion polymerization processes. In addition, the experimental results demonstrated that the molecular weight of copolymer products prepared with AMS copolymers as macromolecular initiators increased steadily with the monomer conversion. Though the polymerization initiated by AMS copolymers was not a well-controlled living system yet, it showed some characteristics of living polymerization. The ESR spectrum presented direct evidence of the generation of carbon centered radicals in the products of copolymer of AMS with glycidyl methacrylate (PAG) heated with j

  8. Well-Defined Triblock Copolymer Containing Perfluoro- cyclobutyl Aryl Ether and Poly(acrylic acid) Segments

    Institute of Scientific and Technical Information of China (English)

    陆国林; 张森; 李永军; 黄晓宇

    2011-01-01

    A novel well-defined triblock copolymer containing perfluorocyclobutyl group was prepared by the combination of mechanism transformation strategy, thermal cycloaddition [2π+2π] polymerization and atom transfer radical polymerization (ATRP). Firstly, a macroinitiator with two ATRP initiating end groups was synthesized by thermal polymerization of 4,4'-bis-(trifluorovinyloxy)biphenyl (BTFVBP) and sequential end-capping with a difunctional compound containing trifluorovinyl and ATRP initiation group. Secondly, this macroinitiator initiated ATRP of t-butyl acrylate to synthesize PtBA-b-PBTFVBP-b-PtBA triblock copolymer. This copolymer was hydrolyzed to afford PAA-b-PBTFVBP-b-PAA amphiphilic triblock copolymer. This kind of fluorine-containing well-defined structure should benefit the study of self-assembly behaviors.

  9. 棉织物基于ATRP接枝HEMA进行抗皱整理的研究%Research on anti-wrinkle treatment for cotton fabrics by using ATRP grafted by HEMA

    Institute of Scientific and Technical Information of China (English)

    程浩南

    2015-01-01

    研究棉织物基于原子转移自由基聚合反应(ATRP)接枝甲基丙烯酸羟乙酯(HEMA)进行抗皱整理的可行性.以棉织物为实验材料,经2-溴异丁酰溴修饰后使其表面具有引发基团,在催化作用下引发ATRP反应接枝HEMA进行抗皱整理,然后测试其抗皱性能的变化,并利用相关测试手段对经过整理后的棉纤维结构变化进行测试分析.结果表明:棉织物基于ATRP接枝HEMA进行抗皱整理后,其抗皱性能得到了显著提高,也验证了该抗皱方法的可行性.同时从红外ATR吸收光谱、扫描电镜图像和X-射线衍射谱可以看出,HEMA被成功接枝到纤维表面,生成的聚合物在棉纤维表面分布相对均匀,且纤维接枝前后的大分子结构基本没有发生变化.

  10. Research on durability of cotton fabrics using anti-wrinkle treatment with ATRP grafted by HEMA%棉织物基于ATRP接枝HEMA进行抗皱整理耐久性的研究

    Institute of Scientific and Technical Information of China (English)

    程浩南

    2015-01-01

    为研究基于原子转移自由基聚合(ATRP)接枝甲基丙烯酸羟乙酯(HEMA)进行的棉织物抗皱整理效果,以棉织物为试验材料,引发ATRP反应接枝HEMA进行抗皱整理后,对经不同次数(5、10、15和20次)水洗和采用不同洗涤剂(洗衣皂、洗衣粉和洗衣液)手洗15次后的棉织物,分别测试其折痕回复角,分析可知:棉织物的折痕回复角随水洗次数增加而逐渐减小,但减小幅度较小,说明该抗皱整理效果具有良好的耐水洗性;采用洗涤剂手洗15次后棉织物的折痕回复角都稍有减小,且15次洗涤剂洗涤与15次水洗效果类似,说明棉织物基于ATRP接枝HEMA进行抗皱整理对洗涤剂洗涤具有较好的耐久性,且具有较好的广谱耐久性.

  11. Grafting PBA onto Surfaces of Nano-Silica via ATRP Reaction & Modification of PVC%ATRP法在纳米SiO2表面接枝PBA及其对PVC的改性

    Institute of Scientific and Technical Information of China (English)

    唐龙祥; 刘榛; 刘春华; 王平华

    2010-01-01

    采用原子转移自由基聚合法(ATRP)在纳米二氧化硅(SiO2)粒子表面接枝聚丙烯酸丁酯(PBA),并以此对聚氯乙烯(PVC)进行改性.红外光谱(FT-IR)、透射电镜(TEM)、扫描电镜(SEM)及力学性能等测试结果表明,所制备的SiO2-g-PBA纳米复合粒子在PVC中分散均匀,使PVC/SO2-g-PBA复合材料的缺口冲击强度及拉伸强度均明显高于PvC及PVC/SiO2复合材料.当SiO2-PBA队纳米复合粒子的质量分数为5%时,PVC/SO2-g-PBA复合材料的冲击强度达到9.5 kJ/m2,较纯PVC提高了280%,同时拉伸强度也有一定的提高,达到了65.3MPa.

  12. Cationization of Inulin via Atom Transfer Radical Polymerization for Gene Delivery%原子转移自由基聚合(ATRP)阳离子化菊粉作为非病毒基因载体的研究

    Institute of Scientific and Technical Information of China (English)

    王静云; 付雪; 包永明

    2014-01-01

    利用原子转移自由基聚合(ATRP)将聚甲基丙烯酸N,N-二甲氨基乙酯[P(DMAEMA)]偶联到菊粉多糖(Inulin)上,合成了新型基因载体PDI N.利用核磁共振仪、动态光散射分析仪、透射电子显微镜和凝胶电泳对PDIN及其与质粒pDNA的复合物进行了表征.凝胶阻滞实验结果表明,PDIN可以通过静电相互作用稳定结合pDNA.噻唑蓝(MTT)细胞毒性测试、溶血实验、绿色荧光蛋白表达质粒(pGFP)及β半乳糖苷酶表达质粒(pβgal)转染实验结果表明,PDIN对MCF-7,Hela,COS7和HepG2细胞的毒性较小;其溶血率低,具有良好的血液相容性;载体PDIN能有效将pGFP和pβgal带入COS7细胞并表达,在N/P为1时转染效率最高,其β半乳糖苷酶的酶活为(3.36±0.74) U/mg蛋白,比Lipo2000转染效率[(4.33 ±0.77) U/mg蛋白]略低.因此,所合成的载体PDIN是一种有潜在应用价值的非病毒基因载体.

  13. SYNTHESIS OF POLY(METHYL METHACRYLATE)-graft-POLYSTYRENE BY ATOM TRANSFER RADICAL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Sheng-min Gong; Qun-sheng Li; Yan Shi; Zhi-feng Fu; Shu-ke Jiao; Wan-tai Yang

    2003-01-01

    The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atom complex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. The obtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate), and its structure was characterized by 1HNMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-grafi-polystyrene. The molecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by 1H-NMR and GPC.

  14. Synthesis of hyperbranched copolymers by combining enzymatic ring-opening polymerization and A TRP from a novel bifunctional initiator

    Institute of Scientific and Technical Information of China (English)

    Al Peng; CHEN Liang; HU Dehua; CHEN Yanhua; LI Dongshuang; ZHANG Bao; SHA Ke; WANG Jingyuan

    2006-01-01

    The hyperbranched aliphatic polyester P(ε-CL) was synthesized by means of Novozyme435-catalyzed ring-opening polymerization (ROP) of BHB (2, 2-bis(hydroxymethyl) butyric acid). The chains ended with hydroxyl of P(ε-CL) were modified by the esterification of α-bromopropionyl bromide to obtain hyperbranched difunctional macroinitiator, which was used in the ATRP of St. CuCI/HMTETA was used as the catalyst system in the reaction of ATRP to acquire the hyperbranched copolymers polystyrene-blockpoly(2,2-bis(hydroxymethyl) butyric acid). The copolymer was confirmed by NMR and GPC.

  15. Synthesis of Graft Copolymers Based on Poly(2‐Methoxyethyl Acrylate) and Investigation of the Associated Water Structure

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Tanaka, Masaru; Ogura, Keiko;

    2012-01-01

    Graft copolymers composed of poly(2‐methoxyethyl acrylate) are prepared employing controlled radical polymerization techniques. Linear backbones bearing atom transfer radical polymerization (ATRP) initiating sites are obtained by reversible addition–fragmentation chain transfer copolymerization...... of 2‐methoxyethyl acrylate (MEA) and 2‐(bromoisobutyryloxy)ethyl methacrylate (BriBuEMA) as well as 2‐hydroxyethyl methacrylate and BriBuEMA in a controlled manner . MEA is then grafted from the linear macroinitiators by Cu (I)‐mediated ATRP. Fairly high molecular weights (>120 000 Da) and low...

  16. Synthesis and Characterization Multi-Block Copolymer PGMA-PBMA-PDMS-PBMA-PGMA by ATRP%多嵌段共聚物PGMA-PBMA-PDMS-PBMA-PGMA的ATRP合成与表征

    Institute of Scientific and Technical Information of China (English)

    周元林; 潘昱; 李迎军; 何方方; 张严金; 罗世凯; 雷卫华

    2012-01-01

    采用聚二甲基硅氧烷大分子(Bf—PDMS-Br)为引发剂,CuCl为催化剂,2,2’-联吡啶(bpy)为配体,甲基丙烯酸丁酯(BMA)和甲基丙烯酸缩水甘油酯(GMA)为单体,通过原子转移自由基聚合(ATRP)法,合成含有反应性环氧基的多嵌段共聚物PGMA-PBMA-PDMS-PBMA—PGMA。利用凝胶渗透色谱(GPC)、红外光谱(IR)、核磁共振(0H—NMR)、原子力显微镜(AFM)和热重分析(TG)方法对其分子量、分子结构、相形态及热稳定性进行研究。研究表明,多嵌段共聚物分子量可控,多分散性低(PDI=1.14~1.40);在微观相上形成有序纳米结构,粒径大小100nm~2μm;多嵌段聚合物低分解温度为270℃。高分解温度为480℃,具有良好的热稳定性;由于引入反应性基团环氧基,大大扩大了其应用范围。%In this paper, multi-block copolymer PGMA-PBMA-PDMS-PBMA-PGMA containing reactivity epoxy group was prepared by atom transfer radical polymerization (ATRP) method. The copolymer is synthesized by using polydimethylsiloxane molecules (Br-PDMS-Br) ended with functional groups as an initiator, cuprous chloride (CuC1) as a catalyst, 2,2'- bipyridine (bpy) as a ligand, rnethacrylate butyl ester (BMA) and glycidyl methacrylate (GMA) as monomers. Its molecular weight, molecular structure, morphology and thermal stability were identified by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), (hydrogen) nuclear magnetic resonance (1H-NMR), atomic force microscopy (AFM) and thermal gravimetric analysis (TG). The results show that molecular weight of the multi-block copolymer can be well controlled, polydispersity of the polymer is as low as 1.14 to 1.40. Microphase ordered nanostrueture is formed of which the particle size is 100 nm--2μm. Compatibility of the components and thermal stability of the multipolymer are great. Low decomposition temperature is 270

  17. Comparative study of the catalytic activity of the complexes Cp{sup *}RuCl(PAr{sub 3}){sub 2} [Ar = -C{sub 6H}5 and 4-CF{sub 3}-C{sub 6}H{sub 4}] in the ATRP of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Hernandez, Alejandro M.; Rosales-Velazquez, Claudia P.; Torres-Lubian, Jose R., E-mail: rtorres@ciqa.mx [Departamento de Sintesis de Polimeros, Centro de Investigacion en Quimica Aplicada, Coah. (Mexico); Saldivar-Guerra, Enrique [Departamento de Procesos de Polimerizacion, Centro de Investigacion en Quimica Aplicada, Coah. (Mexico)

    2011-09-15

    Styrene polymerization by ATRP was conducted independently using the complexes Cp{sup *}RuCl(PPh{sub 3}){sub 2}, and Cp{sup *}RuCl[P(4-CF{sub 3}-C{sub 6}H{sub 4}){sub 3}]{sub 2} as catalysts, in order to evaluate the influence of the electronic properties of the phosphine ligands on the rate and control of the polymerization. The kinetic data for polymerizations carried out with Cp{sup *}RuCl(PPh{sub 3}){sub 2}, show that molecular weights increase linearly with conversion with an average initiation efficiency of 0.77. The molecular weights obtained in the kinetic study with Cp{sup *}RuCl[P(4-CF{sub 3}-C{sub 6}H{sub 4}){sub 3}]{sub 2} also increase with conversion but show a marked deviation below the theoretical molecular weights. This behavior was explained by the gradual, irreversible, oxidation of catalyst Cp{sup *}RuCl[P(4-CF{sub 3}-C{sub 6}H{sub 4}){sub 3}]{sub 2} as confirmed by {sup 31}P-NMR spectroscopy. Catalyst Cp{sup *}RuCl(PPh{sub 3}){sub 2} promotes the polymerization with a rate of polymerization higher than that obtained using Cp{sup *}RuCl[P(4-CF{sub 3}-C{sub 6}H{sub 4}){sub 3}]{sub 2}; this is consistent with the better electron donating properties of PPh{sub 3} versus P(4-CF{sub 3}-C{sub 6}H{sub 4}){sub 3}. Preliminary studies of styrene polymerization by ATRP in supercritical CO{sub 2}, shows that only catalyst Cp{sup *}RuCl[P(4-CF{sub 3}-C{sub 6}H{sub 4}){sub 3}]{sub 2}, with fluorinated ligands, was active. (author)

  18. A NOVEL PHOTO-INITIATING SYSTEM FOR ATOM TRANSFER RADICAL POLYMERIZATION OF STYRENE

    Institute of Scientific and Technical Information of China (English)

    Shu-hui Qin; Dong-qi Qin; Kun-yuan Qiu

    2001-01-01

    A novel photo-induced initiating system, 2,2-dimethoxy-2-phenylacetophenone (DMPA)/ferric tri(N,N-diethyldithiocarbamate) [Fe(DC)3], was developed and used for the atom transfer radical polymerization (ATRP) of styrene in toluene. The polymerization proceeds with DMPA as photo-initiator, Fe(DC)3 as catalyst and DC as a reversible transfer group, while the halogen and ligands are free. Well-defined PSt was prepared and the polymerization mechanism revealed by end group analysis belongs to a reverse ATRP. Block copolymer was prepared by using thus obtained PSt as macroinitiator and Fe(DC)2 as catalyst under UV light irradiation via a conventional ATRP process.``

  19. ARGET ATRP合成大分子偶联剂PMMA-b-PTMSPMA及其对玻璃表面的接枝%Synthesis of Macromolecular Coupling Agent PMMA-b-PTMSPMA by ARGET ATRP and Its Application in Modification of the Glass Surface

    Institute of Scientific and Technical Information of China (English)

    孙婷婷; 任强; 李坚

    2013-01-01

    以电子转移再生催化剂的原子转移自由基聚合(ARGET ATRP)成功合成了大分子硅烷偶联剂即聚甲基丙烯酸甲酯-b-3-甲基丙烯酰氧基丙基三甲氧基硅烷(PMMA-b-PTMSPMA).利用所制得的大分子偶联剂对玻璃表面进行了接枝改性,对改性后的玻璃表面形态及疏水性能进行了研究.结果表明,以CuBr2/PMDETA络合物为催化体系,溴化铜(CuBr2)用量为n(CuBr2)/n(单体)=5×10-4时,PMMA段以辛酸亚锡(Sn(EH)2)为还原剂,PTMSPMA段以铜(Cu)为还原剂,用ARGET ATRP两步法成功制备了嵌段共聚物PMMA-b-PTMSPMA.采用“接枝到(graft onto)”方法,在温和的条件下,在玻璃表面接枝上了大分子偶联剂.玻璃表面的接触角可从30°提高到65°,提高了玻璃表面的疏水性.%Macromolecular silane coupling agent,poly (methyl methacrylate-b-3-methacrylic acyloxy propyl trimethoxysilane) (PMMA-b-PTMSPMA) was successfully synthesized by electron transfer for atom transfer radical polymerization(ARGET ATRP).The structure and properties of block copolymer were characterized by 1H-NMR,GPC and TGA.The morphology and hydrophobic property of grafted glass were investigated.The results show that the block copolymer PMMA-b-PTMSPMA with designed molecular weight of 15000 was successfully synthesized by ARGET ATRP,using CuBr2/PMDETA complex as catalyst system (the catalyst content n (CuBr2) is 5 × 10-4 of n (monomer)).In synthesizing PMMA segment,Sn(EH)2 was used as the reducing agent and in preparing PTMSPMA segment copper was used as the reducing agent.Under mild conditions,the macromolecular coupling agent was grafted onto the surface of glass by the "graft onto" technique.The contact angle of the glass increases from 30° to 70° after the block copolymer grafted onto the glass surface,resulting in the improvement of hydrophobicity of glass surface.The AFM images show that the surface of glass is covered with the different size of aggregates of the block copolymer.

  20. Solution-Stable Colloidal Gold Nanoparticles via Surfactant-Free, Hyperbranched Polyglycerol-b-polystyrene Unimolecular Templates.

    Science.gov (United States)

    Iocozzia, James; Lin, Zhiqun

    2016-07-19

    Hyperbranched polyglycerol-block-polystyrene copolymers, denoted HPG-b-PS, are synthesized and employed as a new and effective unimolecular template for synthesizing colloidal gold (Au) nanoparticles. The coordination of noble metal precursors with polyether within the inner HPG core and subsequent in situ reduction enables the formation of well-dispersed and stable PS-capped Au nanoparticles. The inner HPG core is produced via ring opening multibranching polymerization (ROMBP) and subsequently converted into atom transfer radical polymerization (ATRP) macroinitiators for the controlled growth of polystyrene (PS) arms possessing low polydispersity (PDI < 1.31). An initial investigation into the templating parameters of HPG-b-PS was undertaken by producing templates with different arm numbers (98 and 117) and different PS chain lengths (i.e., molecular weight = 3500-13400 g/mol). It was found that the PS chain length and solvent conditions affect the quality of the resulting PS-capped colloidal Au nanoparticles. This work demonstrates, for the first time, a simple, lower-cost approach for templating nonpolar solvent-soluble PS-capped Au nanoparticles on the order of 10-30 nm in diameter.

  1. Synthesis of Well-Defined Polyethylene-Based 3-Miktoarm Star Copolymers and Terpolymers

    KAUST Repository

    Zhang, Zhen

    2016-03-25

    Novel polyethylene (PE)-based 3-miktoarm star copolymers A2B, (AB)2B and terpolymers (AC)2(BC) [A: PE; B, C: polystyrene (PS) or poly(methyl methacrylate) (PMMA)] were synthesized by combining boron chemistry, polyhomologation, and atom transfer radical polymerization (ATRP). 1,4-Pentadiene-3-yl 2-bromo-2-methylpropanoate was first synthesized followed by hydroboration with thexylborane to afford B-thexylboracyclanes, a multi-heterofunctional initiator with two initiating sites for polyhomologation and one for ATRP. After polyhomologation of dimethylsulfoxonium methylide the α,ω-dihydroxyl polyethylene (PE-OH)2-Br produced served as macroinitiator for the ATRP of styrene to afford (PE-OH)2-(PS-Br). Both (PE-OH)2-Br and (PE-OH)2-(PS-Br) were transformed to two new trifunctional macroinitiators (PE-Br)2-Br and (PE-Br)2-(PS-Br) through esterification reactions and used for the synthesis of (AB)2B and (AC)2(BC) 3-miktoarm star co/terpolymers. All intermediates and final products were characterized by 1H NMR, high temperature gel permeation chromatography (HT-GPC), and differential scanning calorimetry (DSC). The synthetic method is a general one and can be used for the synthesis of complex PE-based architectures by combination with other living/living-controlled polymerization techniques. © 2016 American Chemical Society.

  2. Polyacrylamide Resin Preparation Based on SI-ATRP and Adsorption Property Research of the Resin to 2,4-dichlorophenoxyacetic Acid%基于SI-ATRP技术制备聚丙烯酰胺树脂及研究其对2,4-二氯苯氧乙酸的吸附性能

    Institute of Scientific and Technical Information of China (English)

    田莉莉; 郭燕; 赵艳敏

    2014-01-01

    本试验以氯甲基化交联聚苯乙烯树脂(CMCPS)为载体和大分子引发剂,溴化亚铜/2,2'-联吡啶为催化剂体系,采用了表面引发原子转移自由基聚合技术(SI-ATRP),使丙烯酰胺接枝到CMCPS树脂表面,制得了新型的聚丙烯酰胺树脂(PAM-CMCPS),并且用元素分析和扫描电镜对其进行了表征。考察了该树脂对2,4-二氯苯氧乙酸的吸附性能、动力学和热力学参数。试验结果表明:该树脂对2,4-二氯苯氧乙酸的吸附量随溶液初始浓度和温度的升高而增加,当初始浓度为8 mmol/L时吸附效果最佳,树脂的静态饱和吸附容量为111.01 mg/g, Langmuir和Freundlich方程都能呈现良好的拟合度。热力学平衡方程计算得ΔG0,表明该吸附过程是一个自发、吸热、熵增加的过程。%Polyacrylamide resin was synthesized via surface- initiated atom transfer radical polymerization (SI-ATRP) method. Acrylic amide (AM) was grafted onto the surface of the chloromethyl polystyrene resin by SI-ATRP in the CuBr/2,2'-bipyridine (Bpy) system as catalyst. The compositions of polyacrylamide resin have been determined by means of elementary analysis, and the surface morphology of resin has been observed by scanning electron microscopy (SEM). And the adsorption properties, parameters of kinetics and the thermodynamics of the resin have been evaluated in details, respectively. As the results, Adsorption capacity of 2,4-dichlorophenoxyacetic acid (2,4-D) increases with the increasing of initial concentrations of solution and temperature, and its highest adsorption capacity was obtained with solution concentration of 8 mmol/L, and the static saturation adsorption capacity of resin was 111.01 mg/g. Adsorption isotherm at room temperature has been determined and modeled with Langmuir and Freundlich equations. The thermodynamic equilibrium functions have been calculated to be△G0, hence, the adsorption is spontaneous, endothermic

  3. Optically active micelles from self-assembly of MPEG-b-PMALM copolymer in water

    Institute of Scientific and Technical Information of China (English)

    Fa Bao Zhao; Zhi Lei Liu; Jian Ping Sun; Liang Feng; Ji Wen Hu

    2009-01-01

    Reported here is fabrication of optically active micelles with broad range of morphologies in water,such as spheres,cylinders,and vesicles,from self-assembly of poly(ethylene glycol)monomethyl ether-b-poly-(methacryloyl-L-leacine methyl ester)(MPEG-b-PMALM)copolymer,which was prepared via atom transfer radical polymerization(ATRP)from vinyl monomer bearing chiral amino acid moieties,N-methacryloyl L-leucine methyl ester(MALM),using bromine(Br)end-capped poly(ethylene golycol)monomethylether(MPEG-Br)as macroinitiator in the presence of CuBr/Me6TREN as catalytic system.

  4. Design and Development of Novel Hierarchically Ordered Block Copolymer-Magnetoelectric Particle Nanocomposites

    Science.gov (United States)

    2012-06-08

    dendrimers have been used as templates to prepare zerovalent metal NPs encapsulated within the dendrimer. 17 However, the synthesis of dendrimers... encapsulation of its precursors (e.g., FeCl2·4H2O:FeCl3·6H2O:ammonium hydroxide = 1:1:1 by mole for Fe3O4) within the innermost P4VP regime, followed...radical polymerization (ATRP), in which β- cyclodextrin (β-CD)-based star-like 21-Br--CD with 21 initiating sites was used as macroinitiator 16

  5. Fast and Convenient Synthesis of Amine-Terminated Polylactide as a Macroinitiator for ω-Benzyloxycarbonyl-L-Lysine-N-Carboxyanhydrides

    Directory of Open Access Journals (Sweden)

    Mingjie Ju

    2011-01-01

    Full Text Available Amine-terminated poly (L-lactide (NH2-PLLA with various chain lengths were successfully synthesized by sequential tert-butyl-N-(3-hydroxypropyl carbamate initiated bulk ring-opening polymerization (ROP of L-lactide (L-LA in the presence of Stannous(II 2-ethylhexanoate (Sn(Oct2 and deprotection of the N-tert-butoxycarbonyl (Boc group at the end of the polymer chain. The polymers obtained were characterized by FT-IR, 1H NMR, and GPC method. NH2-PLLA thus prepared was used to initiate the polymerization of ω-benzyloxycarbonyl-L-lysine-N-carboxyanhydride (Lys (Z-NCA, and the result confirmed the high nucleophilicity of the terminal amine group. This method was not only suitable for the preparation of low molecular weight NH2-PLLA, but also quite efficient in the synthesis of high molecular weight samples.

  6. Synthesis and Phase Behavior of Poly(N-isopropylacrylamide-b- Poly(L-Lysine Hydrochloride and Poly(N-Isopropylacrylamide- co-Acrylamide-b-Poly(L-Lysine Hydrochloride

    Directory of Open Access Journals (Sweden)

    Milica Spasojević

    2014-07-01

    Full Text Available The synthesis of poly(N-isopropylacrylamide-b-poly(L-lysine and poly(N- isopropylacrylamide-co-acrylamide-b-poly(L-lysine copolymers was accomplished by combining atom transfer radical polymerization (ATRP and ring opening polymerization (ROP. For this purpose, a di-functional initiator with protected amino group was successfully synthetized. The ATRP of N-isopropylacrylamide yielded narrowly dispersed polymers with consistent high yields (~80%. Lower yields (~50% were observed when narrowly dispersed random copolymers of N-isopropylacrylamide and acrylamide where synthesized. Amino-terminated poly(N-isopropylacrylamide and poly(N-isopropylacrylamide- co-acrylamide were successfully used as macroinitiators for ROP of N6-carbobenzoxy-L- lysine N-carboxyanhydride. The thermal behavior of the homopolymers and copolymers in aqueous solutions was studied by turbidimetry, dynamic light scattering (DLS and proton nuclear magnetic resonance spectroscopy (1H-NMR.

  7. Synthesis of PAA-g-PDEAEMA Dihydrophilic Graft Copolymer and Its Solution Behavior%PAA-g-PDEAEMA全亲水接枝共聚物的合成及其溶液行为

    Institute of Scientific and Technical Information of China (English)

    陆国林; 金维则; 黄晓宇

    2016-01-01

    A new acrylate monomer containing atom transfer radical polymerization (ATRP) initiation group, tert-butyl 2-((2-chloropropanoyloxy)methyl)acrylate (tBCPMA), was first prepared by Baylis-Hillman and esterification reaction. tBCPMA was homopolymerized by reversible addition-fragmentation chain transfer (RAFT) in a controlled way to obtain well-defined macroinitia-tor (PtBCPMA) with ATRP initiation group (—COCHClCH3) on each repeated unti. The PtBCPMA macroinitiator initiated ATRP of DEAEMA to synthesize PtBA-g-PDEAEMA, which was selectively hydrolyzed to obtain PAA-g-PDEAEMA dihydrophilic copolymer. Lastly, the effect of pH values on their critical micelle concentration (cmc) and micellar morphologies were investigated.%通过 Baylis-Hillman 和酯化两步反应得到一种含原子转移自由基聚合(ATRP)引发基团的含氯三官能团单体tBCPMA,通过该单体可逆加成-断裂链转移(RAFT)均聚可得到每个重复单元含有ATRP引发基团(—COCHClCH3)的大分子引发剂PtBCPMA。PtBCPMA引发单体DEAEMA的ATRP聚合得到接枝共聚物PtBA-g-PDEAEMA,选择性水解PtBA-g-PDEAEMA得到全亲水接枝共聚物PAA-g-PDEAEMA。最后研究了pH值的变化对它们的临界胶束浓度和胶束形貌的影响。

  8. Simulating Controlled Radical Polymerizations with mcPolymer—A Monte Carlo Approach

    Directory of Open Access Journals (Sweden)

    Georg Drache

    2012-07-01

    Full Text Available Utilizing model calculations may lead to a better understanding of the complex kinetics of the controlled radical polymerization. We developed a universal simulation tool (mcPolymer, which is based on the widely used Monte Carlo simulation technique. This article focuses on the software architecture of the program, including its data management and optimization approaches. We were able to simulate polymer chains as individual objects, allowing us to gain more detailed microstructural information of the polymeric products. For all given examples of controlled radical polymerization (nitroxide mediated radical polymerization (NMRP homo- and copolymerization, atom transfer radical polymerization (ATRP, reversible addition fragmentation chain transfer polymerization (RAFT, we present detailed performance analyses demonstrating the influence of the system size, concentrations of reactants, and the peculiarities of data. Different possibilities were exemplarily illustrated for finding an adequate balance between precision, memory consumption, and computation time of the simulation. Due to its flexible software architecture, the application of mcPolymer is not limited to the controlled radical polymerization, but can be adjusted in a straightforward manner to further polymerization models.

  9. Capability approach

    DEFF Research Database (Denmark)

    Jensen, Niels Rosendal; Kjeldsen, Christian Christrup

    Lærebogen er den første samlede danske præsentation af den af Amartya Sen og Martha Nussbaum udviklede Capability Approach. Bogen indeholder en præsentation og diskussion af Sen og Nussbaums teoretiske platform. I bogen indgår eksempler fra såvel uddannelse/uddannelsespolitik, pædagogik og omsorg....

  10. Pedagogical approaches

    DEFF Research Database (Denmark)

    Lund Larsen, Lea

    in formal settings, but in most teaching settings, the teachers act alone and develop their pedagogical approaches/- teaching strategies with no synchronous sparring from a colleague. Adult learners have particular needs and characteristics that their teachers must be able to address (cf. Knowles...

  11. Synthesis of thermoresponsive polystyrene-based comb-type grafted poly(N-isopropylacrylamide)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Narrowly distributed polystyrene-g-p(N-isopropylacrylamide) (PSt-g-PNIPAM) was prepared by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using the brominated polystyrene as macroinitiator and CuCl combined with hexamethyltriethylenetetramine as catalyst. Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy confirmed the structure of PSt-g-PNIPAM. The gel permeation chromatography (GPC) showed that the graft copolymer had a single distribution peak with molecular weight, Mn (g/mol) of 19815 g/mol (using polystyrene as the standard). Differential scanning calorimetry (DSC) revealed that due to both effects of hydrophobic isopropyl groups and hydrogen bonds in the amide group, the glass transition temperature (Tg) of PSt-g-PNIPAM enhanced 16.0℃ compared to the Tg of the polystyrene.

  12. Novel fluorescent amphiphilic block copolymers: photophysics behavior and interactions with DNA

    Directory of Open Access Journals (Sweden)

    2007-06-01

    Full Text Available In this study, novel amphiphilic fluorescent copolymers poly(N-vinylpyrrolidone-b-poly(N-methacryloyl-N'-(α-naphthylthiourea (PVP-b-PNT were synthesized via ATRP with poly(N-vinylpyrrolidone-Cl as macroinitiator and N-methacryloyl-N'-α-naphthylthiourea (NT as hydrophobic segment. PVP-b-PNT copolymers were characterized by 1H NMR, GPC-MALLS and fluorescence measurements. The aggregation behavior of PVP-b-PNT in water was investigated by transmission electron microscope (TEM and dynamic light scattering (DLS measurement. The photophysics behavior of PVP-b-PNT showed that block copolymer formed strong excimer. The interaction of DNA with the block copolymer made the excimer of block copolymer quench. The cytotoxicity result of PVP-b-PNT in cell culture in vitro indicated that this copolymer PVP-b-PNT had good biocompatibility.

  13. Photo-cross-linkable thermoresponsive star polymers designed for control of cell-surface interactions.

    Science.gov (United States)

    Park, Sangwoo; Cho, Hong Yul; Yoon, Jeong Ae; Kwak, Yungwan; Srinivasan, Abiraman; Hollinger, Jeffrey O; Paik, Hyun-jong; Matyjaszewski, Krzysztof

    2010-10-11

    Star polymers with thermoresponsive arms, consisting of 2-(2-methoxyethoxy)ethyl methacrylate (MEO₂MA) and oligo(ethylene glycol) methacrylate with ~4 ethylene oxide units (OEOMA₃₀₀, M(n) = 300), were synthesized via atom transfer radical polymerization (ATRP). 25% of the arms contained benzophenone chain-end functionality at the star periphery. A mixture of linear poly(MEO₂MA-co-OEOMA₃₀₀)-Br macroinitiators without and with benzophenone end-group macroinitiators were (MI and Bzp-MI, respectively) cross-linked with ethylene glycol dimethacrylate to form star polymers. Formation of star polymers was monitored by GPC, and the presence of benzophenone functionality in the stars was confirmed by ¹H NMR. The UV-vis spectroscopy revealed that the star polymers exhibit the low critical solution temperature (LCST) at 27 °C, slightly lower than LCST of either MI or Bzp-MI. Commercially available tissue culture grade polystyrene surface was modified by depositing a thin film of functionalized stars and UV cross-linking (λ = 365 nm). The star polymers covalently attached onto surfaces allowed a control of cell shrinkage and attachment in response to temperature changes.

  14. Nitroxide mediated and atom transfer radical graft polymerization of atactic polymers onto syndiotactic polystyrene

    Directory of Open Access Journals (Sweden)

    M. Abbasian

    2012-06-01

    Full Text Available 'Living' radical graft polymerization was employed to prepare graft copolymers with nitroxide-mediated arylated syndiotactic polystyrene as the backbone and polystyrene (PS, poly(p-methylstyrene (PMS and poly(methylmethacrylate (PMMA as branches. A two-stage process has been developed to synthesize the macroinitiator. First, syndiotactic polystyrene (sPS was modified by the Friedel-Crafts reaction to introduce chlorine; second, the chlorine groups were converted to nitroxide mediated groups by coupling with 1-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO-OH. The resulting macroinitiator (sPS-TEMPO for 'living' free radical polymerization was then heated in the presence of styrene and p-methylstyrene to form graft and block copolymers. We used the obtained copolymer and N-bromosuccinimide as brominating agent to achieve polymers with bromine groups. This brominated copolymer was used as a macroinitiator for polymerizing methyl methacrylate in the presence of the CuBr/bpy catalyst system. The formation of the graft and block copolymers was confirmed by DSC, ¹H NMR and FTIR spectroscopy. This approach using macroinitiators is an effective method for the preparation of new materials.

  15. Nitroxide mediated and atom transfer radical graft polymerization of atactic polymers onto syndiotactic polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Abbasian, M. [Department of Basic Science, Payame Noor University, Tehran (Iran, Islamic Republic of); Shoja, S. Esmaeily [Lab. of Materials, Faculty of Engineering, Islamic Azad University, Bonab (Iran, Islamic Republic of)

    2012-04-15

    'Living' radical graft polymerization was employed to prepare graft copolymers with nitroxide mediated arylated syndiotactic polystyrene as the backbone and polystyrene (PS), poly(p-methylstyrene) (PMS) and poly(methylmethacrylate) (PMMA) as branches. A two-stage process has been developed to synthesize the macroinitiator. First, syndiotactic polystyrene (sPS) was modified by the Friedel-Crafts reaction to introduce chlorine; second, the chlorine groups were converted to nitroxide mediated groups by coupling with 1-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO-OH). The resulting macroinitiator (sPSTEMPO) for 'living' free radical polymerization was then heated in the presence of styrene and pmethylstyrene to form graft and block copolymers. We used the obtained copolymer and N-bromosuccinimide as brominating agent to achieve polymers with bromine groups. This brominated copolymer was used as a macroinitiator for polymerizing methyl methacrylate in the presence of the CuBr/bpy catalyst system. The formation of the graft and block copolymers was confirmed by DSC, {sup 1}H NMR and FTIR spectroscopy. This approach using macroinitiators is an effective method for the preparation of new materials. (author)

  16. Functionalization of magnetic nanoparticles with dendritic-linear-brush-like triblock copolymers and their drug release properties.

    Science.gov (United States)

    He, Xiaohua; Wu, Xiaomeng; Cai, Xin; Lin, Shaoliang; Xie, Meiran; Zhu, Xinyuan; Yan, Deyue

    2012-08-14

    Novel water-soluble dendritic-linear-brush-like triblock copolymer polyamidoamine-b-poly(2-(dimethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate) (PAMAM-b-PDMAEMA-b-PPEGMA)-grafted superparamagnetic iron oxide nanoparticles (SPIONs) were successfully prepared via a two-step copper-mediated atom transfer radical polymerization (ATRP) method. The macroinitiators were immobilized on the surface of Fe(3)O(4) nanoparticles via effective ligand exchange of oleic acid with the propargyl focal point PAMAM-typed dendron (generation 2.0, denoted as propargyl-D(2.0)) containing four carboxyl acid end groups, following a click reaction with 2'-azidoethyl-2-bromoisobutylate (AEBIB). PDMAEMA and PPEGMA were grown gradually from nanoparticle surfaces using the "grafting from" approach, which rendered the SPIONs soluble in water and reversed aggregation. To the best of our knowledge, this is the first report that describes the functionalization of magnetic nanoparticles with dendritic-linear-brush-like triblock copolymers. The modified nanoparticles were systematically studied via TEM, FT-IR, DLS, XRD, NMR, TGA, and magnetization measurements. DLS measurement confirmed that the obtained dendritic-linear-brush-like triblock copolymer-grafted SPIONs had a uniform hydrodynamic particle size of average diameter less than 30 nm. The dendritic-linear-brush-like triblock copolymer-grafted SPIONs possessed excellent biocompatibility by methyl tetrazolium (MTT) assays against NIH3T3 cells and hemolysis assays with rabbit erythrocytes. Furthermore, an anticancer drug, doxorubicin (Dox), was used as a model drug and loaded into the dendritic-linear-brush-like triblock copolymer-grafted SPIONs, and subsequently, the drug releases were performed in phosphoric acid buffer solution pH = 4.7, 7.4, or 11.0 at 37 °C. The results verify that the dendritic-linear-brush-like triblock copolymer-grafted SPIONs possess pH-responsive drug release behavior. The Dox dose

  17. FORMATION OF FLOWER-LIKE AGGREGATES FROM SELF-ASSEMBLING OF MICELLES WITH PEO SHELLS AND CROSS-LINKED POLYACRYLAMIDE CORES

    Institute of Scientific and Technical Information of China (English)

    Chuan-qun Huang; Chun-yan Hong; Cai-yuan Pan

    2008-01-01

    Amphiphilic block copolymers, poly(ethylene oxide)-b-poly(N-acryloxysuccinimide) (PEO-b-PNAS) with various molecular weights have been successfully synthesized by atom transfer radical polymerization (ATRP) of NAS using functionalized PEO (PEO-Br) as ATRP macroinitiator. The self-assembling of the block copolymers in water, which is a good solvent for PEO and a non-solvent for PNAS, yielded spherical core-shell micelles with PNAS as core and PEO as shell. The cross-linked reaction of oxysuccinimide in PNAS chains with ethylenediamine occurred in the core of micelles,and the core cross-linked micelles were formed. The flower-like and dendritic aggregates were formed by self-assembling of the core cross-linked micelles on the glass slides or silicon wafers. Longer PNAS block in the block copolymers and higher evaporation temperature formed bigger spherical particles. The optical microscope was used to follow the formation and growth of the flower-like aggregates from the colloidal solution and the main driving forces for the self-assembling are solution fluid and interactions between PEO chains.

  18. Synthesis and ATRP of novel fluorinated aromatic monomer with pendant sulfonate group

    DEFF Research Database (Denmark)

    Dimitrov, Ivaylo; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    Novel, fluorinated monomer with pendant sulfonate group was synthesized utilizing a two-step derivatization of 2,3,4,5,6-pentafluorostyrene (FS). The first step was a nucleophilic substitution of the fluorine atom in para position by hydroxyl group followed by sulfopropylation. The monomer was po...

  19. Modification of Jute Fibers with Polystyrene via Atom Transfer Radical Polymerization

    DEFF Research Database (Denmark)

    Plackett, David; Jankova, Katja Atanassova; Egsgaard, Helge;

    2005-01-01

    Atom transfer radical polymerization (ATRP) was investigated as a method of covalently bonding polystyrene to jute (Corchorus capsularis) and as a possible approach to fiber composites with enhanced properties. Jute fibers were modified with a brominated initiator and subsequently ATRP modified...... to attach polystyrene and then examined using SEM, DSC, TGA, FTIR, XPS, elemental analysis, and Py-GC-MS. These techniques confirmed that polystyrene had been covalently bound to the fibers and consequently ATRP-modified jute fiber mats were used to prepare hot-pressed polystyrene composites. Composite...... applications, we conclude that further optimization of the ATRP method is required, possibly targeting higher and more uniform loading of polystyrene on the fibers....

  20. Surface-Initiated Atom Transfer Radical Polymerization and Electrografting Technique as a Means For Attaining Tailor-Made Polymer Coatings

    DEFF Research Database (Denmark)

    Chernyy, Sergey

    2012-01-01

    Atom transfer radical polymerization initiated from a surface of various substrates (SI-ATRP) has become a progressively popular technique for obtaining thin polymer films with predetermined properties. The present work addresses the main features of SI-ATRP with respect to the controllability......, rates of polymerization, suitable monomers, reaction mixture compositions etc. An alternative potential-driven polymerization approach is discussed, although to a smaller extent. Chapter 1 provides an overview of controlled/living polymerization techniques with an accent made on ATRP. Different...... strategies for initiator grafting, physicochemical properties of polymer brushes and basic principles of quartz crystal microbalance technique (QCM) are discussed. In Chapter 2 various ATRP conditions are probed. The effects of solvent polarity, monomer concentration, initiator surface density, ligand nature...

  1. Complementary Health Approaches

    Science.gov (United States)

    ... on some complementary approaches, such as acupuncture and yoga, but there have been fewer studies on other approaches, so much less is known about them. The National Institutes of Health (NIH) is sponsoring research to learn more about ...

  2. Evaluating six soft approaches

    Directory of Open Access Journals (Sweden)

    Lene Sørensen

    2008-09-01

    Full Text Available The paper introduces and evaluates six soft approaches used in strategy development and planning. We take a planner’s perspective on discussing the concepts of strategy development and planning. This means that we see strategy development and planning as learning processes based on Ackoff’s interactive planning principles to be supported by soft approaches in carrying out the principles in action. These six soft approaches are suitable for supporting various steps of the strategy development and planning process. These are the SWOT analysis, the Future Workshop, the Scenario methodology, Strategic Option Development and Analysis, Strategic Choice Approach and Soft Systems Methodology. Evaluations of each methodology are carried out using a conceptual framework in which the organisation, the result, the process and the technology of the specific approach are taken into consideration. Using such a conceptual framework for evaluations of soft approaches increases the understanding of them, their transparency, and their usability in practice.

  3. The sustainable livelihoods approach

    DEFF Research Database (Denmark)

    Oelofse, Myles; Jensen, Henning Høgh

    2008-01-01

    food chain has on producers and their families, an analysis was conducted of the use of the Sustainable Livelihoods Approach (SLA). The SLA provides a holistic and integrative approach which researchers can use as the overriding frame for their research. The application of the approach is recommended...... as it enables us to maintain important elements of the sustainability vision, yet emphasises that a number of assets influence farmers' livelihoods and it maintains the focus on salience, legitimacy, and credibility in the research....

  4. Intradural anterior transpetrosal approach.

    Science.gov (United States)

    Ichimura, Shinya; Hori, Satoshi; Hecht, Nils; Czabanka, Marcus; Vajkoczy, Peter

    2016-10-01

    The standard anterior transpetrosal approach (ATPA) for petroclival lesions is fundamentally an epidural approach and has been practiced for many decades quite successfully. However, this approach has some disadvantages, such as epidural venous bleeding around foramen ovale. We describe here our experience with a modified technique for anterior petrosectomy via an intradural approach that overcomes these disadvantages. Five patients with petroclival lesions underwent surgery via the intradural ATPA. The intraoperative hallmarks are detailed, and surgical results are reported. Total removal of the lesions was achieved in two patients with petroclival meningioma and two patients with pontine cavernoma, whereas subtotal removal was achieved in one patient with petroclival meningioma without significant morbidity. No patient experienced cerebrospinal fluid leakage. The intradural approach is allowed to tailor the extent of anterior petrosectomy to the individually required exposure, and the surgical procedure appeared to be more straightforward than via the epidural route. Caveats encountered with the approach were the temporal basal veins that could be spared as well as identification of the petrous apex due to the lack of familial epidural landmarks. The risk of injury to the temporal bridging veins is higher in this approach than in the epidural approach. Intradural approach is recommended in patients with a large epidural venous route, such as sphenobasal and sphenopetrosal vein. Navigation via bone-window computed tomography is useful to identify the petrous apex.

  5. Evaluating six soft approaches

    DEFF Research Database (Denmark)

    Sørensen, Lene Tolstrup; Vidal, Rene Victor Valqui

    2008-01-01

    's interactive planning principles to be supported by soft approaches in carrying out the principles in action. These six soft approaches are suitable forsupporting various steps of the strategy development and planning process. These are the SWOT analysis, the Future Workshop, the Scenario methodology......, Strategic Option Development and Analysis, Strategic Choice Approach and Soft Systems Methodology. Evaluations of each methodology are carried out using a conceptual framework in which the organisation, the result, the process and the technology of the specific approach are taken into consideration. Using...

  6. Evaluating Six Soft Approaches

    DEFF Research Database (Denmark)

    Sørensen, Lene Tolstrup; Valqui Vidal, René Victor

    2008-01-01

    's interactive planning principles to be supported by soft approaches in carrying out the principles in action. These six soft approaches are suitable forsupporting various steps of the strategy development and planning process. These are the SWOT analysis, the Future Workshop, the Scenario methodology......, Strategic Option Development and Analysis, Strategic Choice Approach and Soft Systems Methodology. Evaluations of each methodology are carried out using a conceptual framework in which the organisation, the result, the process and the technology of the specific approach are taken into consideration. Using...

  7. A Comparison on the Audiolingual Approach and the Communicative Approach

    Institute of Scientific and Technical Information of China (English)

    代海娜

    2015-01-01

    Audiolingual approach and communicative approach are two important approaches in language teaching.In this paper,some differences and both advantages and diadvantages will be discussed.Thus,to conduct the important usage of approachs in language teaching.

  8. The TLC Approach.

    Science.gov (United States)

    Welker, William A.

    2002-01-01

    Notes how the author has developed the Teaching and Learning Cues (TLC) approach, an offspring of textbook organizational patterns instruction that stresses the significance of certain words and phrases in reading. Concludes that with the TLC approach, students learn to appreciate the important role cue words and phrases play in understanding…

  9. Stuttering-Psycholinguistic Approach

    Science.gov (United States)

    Hategan, Carolina Bodea; Anca, Maria; Prihoi, Lacramioara

    2012-01-01

    This research promotes psycholinguistic paradigm, it focusing in delimitating several specific particularities in stuttering pathology. Structural approach, on language sides proves both the recurrent aspects found within specialized national and international literature and the psycholinguistic approaches dependence on the features of the…

  10. Approaches to understand culture

    DEFF Research Database (Denmark)

    Rasmussen, Lauge Baungaard; Rauner, Felix

    1996-01-01

    Different approaches to understand the concept ofculture are presented and evaluated. The author'sconcept of culture is defined. Different aspectsof the concept are discussed.......Different approaches to understand the concept ofculture are presented and evaluated. The author'sconcept of culture is defined. Different aspectsof the concept are discussed....

  11. Articulating Design Approaches?

    DEFF Research Database (Denmark)

    Kensing, Finn; Bødker, Keld; Simonsen, Jesper

    We are working on an approach for designing CSCW systems since we advocate the importance of generalizing from own work practice as designers and from studies of designers working under industrial conditions. We use the term approach as something in between commodified methods and isolated techni...

  12. Modular Approach for Ethics

    Science.gov (United States)

    Wyne, Mudasser F.

    2010-01-01

    It is hard to define a single set of ethics that will cover an entire computer users community. In this paper, the issue is addressed in reference to code of ethics implemented by various professionals, institutes and organizations. The paper presents a higher level model using hierarchical approach. The code developed using this approach could be…

  13. Life Span Developmental Approach

    Directory of Open Access Journals (Sweden)

    Ali Eryilmaz

    2011-03-01

    Full Text Available The Life Span Developmental Approach examines development of individuals which occurs from birth to death. Life span developmental approach is a multi-disciplinary approach related with disciplines like psychology, psychiatry, sociology, anthropology and geriatrics that indicates the fact that development is not completed in adulthood, it continues during the life course. Development is a complex process that consists of dying and death. This approach carefully investigates the development of individuals with respect to developmental stages. This developmental approach suggests that scientific disciplines should not explain developmental facts only with age changes. Along with aging, cognitive, biological, and socioemotional development throughout life should also be considered to provide a reasonable and acceptable context, guideposts, and reasonable expectations for the person. There are three important subjects whom life span developmental approach deals with. These are nature vs nurture, continuity vs discontinuity, and change vs stability. Researchers using life span developmental approach gather and produce knowledge on these three most important domains of individual development with their unique scientific methodology.

  14. Introducing Systems Approaches

    Science.gov (United States)

    Reynolds, Martin; Holwell, Sue

    Systems Approaches to Managing Change brings together five systems approaches to managing complex issues, each having a proven track record of over 25 years. The five approaches are: System Dynamics (SD) developed originally in the late 1950s by Jay Forrester Viable Systems Model (VSM) developed originally in the late 1960s by Stafford Beer Strategic Options Development and Analysis (SODA: with cognitive mapping) developed originally in the 1970s by Colin Eden Soft Systems Methodology (SSM) developed originally in the 1970s by Peter Checkland Critical Systems Heuristics (CSH) developed originally in the late 1970s by Werner Ulrich

  15. Otoplasty: A graduated approach.

    Science.gov (United States)

    Foda, H M

    1999-01-01

    Numerous otoplastic techniques have been described for the correction of protruding ears. Technique selection in otoplasty should be done only after careful analysis of the abnormal anatomy responsible for the protruding ear deformity. A graduated surgical approach is presented which is designed to address all contributing factors to the presenting auricular deformity. The approach starts with the more conservative cartilage-sparing suturing techniques, then proceeds to incorporate other more aggressive cartilage weakening maneuvers. Applying this approach resulted in better long-term results with less postoperative lateralization than that encountered on using the cartilage-sparing techniques alone.

  16. Hormonal approach in Hirsutism

    OpenAIRE

    Abdullah, Nusratuddin

    2015-01-01

    Hinsutism is a clinical sign that primarily indicate androgen excess and open caused hy relatively benign junctional conditions. Hirsutism requires a careful and systematic clinical evaluation coztoleal with a rational approach to treatment. Initiate therapy only in patients who give informed consent after a complete explanation of the potential benejits and risks of a particular treatment and alternative approaches. The goals ofthe correct management of hirsutism are to ame...

  17. The electronic approach VSCF

    Science.gov (United States)

    Hladky, Mark

    The advantages of the high-power electronic approach to variable speed constant frequency (VSCF) systems are examined. It is shown, in particular, how the inherent flexibility of the VSCF approach allows it to be configured for different applications, contributing to the evolution towards the more electric aircraft. The discussion covers criteria for selection, aircraft electric power system architectures, power level, performance, reliability, and maintainability. The future trends of the VSCF converter technology are also briefly discussed.

  18. Sustainable fashion: New approaches

    OpenAIRE

    Niinimäki, Kirsi

    2013-01-01

    This publication is intended to be used as a source of inspiration for designers and companies, and all stakeholders whose interest lies in the area of sustainable fashion. While the strategies for sustainability are complex and approaches are many, this publication presents only a few ways to approach sustainable fashion. I hope the publication offers inspiration on how to make positive change in current practices and how to effect new mindsets, creating transformative fashion. Theoretica...

  19. Theoretical Approaches to Coping

    Directory of Open Access Journals (Sweden)

    Sofia Zyga

    2013-01-01

    Full Text Available Introduction: Dealing with stress requires conscious effort, it cannot be perceived as equal to individual's spontaneous reactions. The intentional management of stress must not be confused withdefense mechanisms. Coping differs from adjustment in that the latter is more general, has a broader meaning and includes diverse ways of facing a difficulty.Aim: An exploration of the definition of the term "coping", the function of the coping process as well as its differentiation from other similar meanings through a literature review.Methodology: Three theoretical approaches of coping are introduced; the psychoanalytic approach; approaching by characteristics; and the Lazarus and Folkman interactive model.Results: The strategic methods of the coping approaches are described and the article ends with a review of the approaches including the functioning of the stress-coping process , the classificationtypes of coping strategies in stress-inducing situations and with a criticism of coping approaches.Conclusions: The comparison of coping in different situations is difficult, if not impossible. The coping process is a slow process, so an individual may select one method of coping under one set ofcircumstances and a different strategy at some other time. Such selection of strategies takes place as the situation changes.

  20. Personal Approaches to Career Planning.

    Science.gov (United States)

    DeMont, Billie; DeMont, Roger

    1983-01-01

    Identifies four approaches to career planning based on situational leadership theory: the network approach, self-help approach, engineering approach, and mentor approach. Guidelines for the selection of a planning method based on the nature of the work environment and personal preference are discussed. (JAC)

  1. Approaching a Postcolonial Arctic

    DEFF Research Database (Denmark)

    Jensen, Lars

    2016-01-01

    This article explores different postcolonially configured approaches to the Arctic. It begins by considering the Arctic as a region, an entity, and how the customary political science informed approaches are delimited by their focus on understanding the Arctic as a region at the service...... of the contemporary neoliberal order. It moves on to explore how different parts of the Arctic are inscribed in a number of sub-Arctic nation-state binds, focusing mainly on Canada and Denmark. The article argues that the postcolonial can be understood as a prism or a methodology that asks pivotal questions to all...... approaches to the Arctic. Yet the postcolonial itself is characterised by limitations, not least in this context its lack of interest in the Arctic, and its bias towards conventional forms of representation in art. The article points to the need to develop a more integrated critique of colonial and neo...

  2. Approaches to Methadone Treatment

    DEFF Research Database (Denmark)

    Järvinen, Margaretha

    2008-01-01

    The paper analyses methadone treatment in Copenhagen – as it is described by methadone users and staff at different outpatient centres. The starting point is a theoretical model distinguishing between two different approaches to methadone treatment: ‘palliative’ and ‘curative’. Included...... in the model are three dimensions (1) treatment goals at the methadone centres (abstinence vs. stabilisation) (2) treatment focus (focus on addiction vs. focus on the consequences of addiction) and (3) conceptualisation of methadone (methadone as similar to or different from heroin). The paper shows...... that there is a discrepancy between the attitudes of the staff and those of the users. While the staff favour an almost clear-cut palliative approach to methadone treatment, defining curative goals as both unrealistic and as belonging to the past, the users prefer an approach that does not exclude the goal of abstinence...

  3. Life History Approach

    DEFF Research Database (Denmark)

    Olesen, Henning Salling

    2015-01-01

    as in everyday life. Life histories represent lived lives past, present and anticipated future. As such they are interpretations of individuals’ experiences of the way in which societal dynamics take place in the individual body and mind, either by the individual him/herself or by another biographer. The Life...... History approach was developing from interpreting autobiographical and later certain other forms of language interactive material as moments of life history, i.e. it is basically a hermeneutic approach. Talking about a psycho-societal approach indicates the ambition of attacking the dichotomy...... of the social and the psychic, both in the interpretation procedure and in some main theoretical understandings of language, body and mind. My article will present the reflections on the use of life history based methodology in learning and education research as a kind of learning story of research work....

  4. Technical approach document

    Energy Technology Data Exchange (ETDEWEB)

    1989-12-01

    The Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978, Public Law 95-604 (PL95-604), grants the Secretary of Energy the authority and responsibility to perform such actions as are necessary to minimize radiation health hazards and other environmental hazards caused by inactive uranium mill sites. This Technical Approach Document (TAD) describes the general technical approaches and design criteria adopted by the US Department of Energy (DOE) in order to implement remedial action plans (RAPS) and final designs that comply with EPA standards. It does not address the technical approaches necessary for aquifer restoration at processing sites; a guidance document, currently in preparation, will describe aquifer restoration concerns and technical protocols. This document is a second revision to the original document issued in May 1986; the revision has been made in response to changes to the groundwater standards of 40 CFR 192, Subparts A--C, proposed by EPA as draft standards. New sections were added to define the design approaches and designs necessary to comply with the groundwater standards. These new sections are in addition to changes made throughout the document to reflect current procedures, especially in cover design, water resources protection, and alternate site selection; only minor revisions were made to some of the sections. Sections 3.0 is a new section defining the approach taken in the design of disposal cells; Section 4.0 has been revised to include design of vegetated covers; Section 8.0 discusses design approaches necessary for compliance with the groundwater standards; and Section 9.0 is a new section dealing with nonradiological hazardous constituents. 203 refs., 18 figs., 26 tabs.

  5. Radiolab - three different approaches

    DEFF Research Database (Denmark)

    Lønstrup, Ansa

    2012-01-01

    different scholarly approaches to sound studies. The object was selected by Torben Sangild, who was familiar with the chosen context: the signature of the US radio programme and podcast Radiolab. The two other participants did not know the context and chose to analyse the sound object without further...... object with a global audience, taken from one of the most popular podcasts worldwide, accessible on the internet. Finally, it is a piece of functional sound design, rather than a work of art, which raises the question of context more clearly. The result is three rather different approaches: 1) a process...

  6. Financial Management: An Organic Approach

    Science.gov (United States)

    Laux, Judy

    2013-01-01

    Although textbooks present corporate finance using a topical approach, good financial management requires an organic approach that integrates the various assignments financial managers confront every day. Breaking the tasks into meaningful subcategories, the current article offers one approach.

  7. Marxian Approaches to Education.

    Science.gov (United States)

    Carnoy, Martin

    Traditional Marxist approaches to the state relegate superstructural institutions like the school to a minor role in the process of social change. More recent theories like those of Gramsci, Althusser, and Poulantzas raise the state and the class struggle in the state apparatuses to a much more prominent position: superstructure, including the…

  8. Islamic approach in counseling.

    Science.gov (United States)

    Hanin Hamjah, Salasiah; Mat Akhir, Noor Shakirah

    2014-02-01

    A religious approach is one of the matters emphasized in counseling today. Many researchers find that there is a need to apply the religious element in counseling because religion is important in a client's life. The purpose of this research is to identify aspects of the Islamic approach applied in counseling clients by counselors at Pusat Kaunseling Majlis Agama Islam Negeri Sembilan (PKMAINS). In addition, this research also analyses the Islamic approach applied in counseling at PKMAINS with reference to al-Quran and al-Sunnah. This is a qualitative research in the form of case study at PKMAINS. The main method used in this research is interview. The research instrument used is interview protocol. The respondents in this study include 9 counselors who serve in one of the counseling centers in Malaysia. This study also uses questionnaire as an additional instrument, distributed to 36 clients who receive counseling service at the center. The findings of the study show that the Islamic approach applied in counseling at PKMAINS may be categorized into three main aspects: aqidah (faith), ibadah (worship/ultimate devotion and love for God) and akhlaq (moral conduct). Findings also show that the counseling in these aspects is in line with Islamic teachings as contained in al-Quran and al-Sunnah.

  9. Implementation of Communicative Approach

    Science.gov (United States)

    Jabeen, Shazi Shah

    2014-01-01

    In the contemporary age of high professional requirements such as excellent communicative skills, the need for successful learning of communicative skills of English language suggests communicative ability to be the goal of language teaching. In other words, to teach English language using communicative approach becomes essential. Studies to…

  10. Orion Emergency Mask Approach

    Science.gov (United States)

    Tuan, George C.; Graf, John C.

    2009-01-01

    Emergency mask approach on Orion poses a challenge to the traditional Shuttle or Station approaches. Currently, in the case of a fire or toxic spill event, the crew utilizes open loop oxygen masks that provide the crew with oxygen to breath, but also dumps the exhaled oxygen into the cabin. For Orion, with a small cabin volume, the extra oxygen will exceed the flammability limit within a short period of time, unless a nitrogen purge is also provided. Another approach to a fire or toxic spill event is the use of a filtering emergency masks. These masks utilize some form of chemical beds to scrub the air clean of toxic providing the crew safe breathing air for a period without elevating the oxygen level in the cabin. Using the masks and a form of smoke-eater filter, it may be possible to clean the cabin completely or to a level for safe transition to a space suit to perform a cabin purge. Issues with filters in the past have been the reaction time, breakthroughs, and high breathing resistance. Development in a new form of chemical filters has shown promise to make the filtering approach feasible.

  11. Adopting a Pluricentric Approach

    Science.gov (United States)

    van Kerckvoorde, Colette

    2012-01-01

    This article argues for a "D-A-CH" approach, which stands for Germany (D), Austria (A), and Switzerland (CH), in language classes from the introductory level on. I begin by tracing the emergence and development of distinct Standard Swiss and Austrian German varieties. I then discuss marketing efforts for Swiss and Austrian German, and…

  12. Evaluating six soft approaches

    DEFF Research Database (Denmark)

    Sørensen, Lene; Vidal, Rene Victor Valqui

    2006-01-01

    The paper introduces and evaluates six soft approaches used in strategy development and planning. We take a planner’s perspective on discussing the concepts of strategy development and planning. This means that we see strategy development and planning as learning processes based on Ackoff’s inter...

  13. The Capability Approach

    NARCIS (Netherlands)

    I.A.M. Robeyns (Ingrid)

    2011-01-01

    textabstract In its most general description, the capability approach is a flexible and multi-purpose normative framework, rather than a precise theory of well-being, freedom or justice. At its core are two normative claims: first, the claim that the freedom to achieve well-being is of primary mora

  14. Approaches to acceptable risk

    Energy Technology Data Exchange (ETDEWEB)

    Whipple, C.

    1997-04-30

    Several alternative approaches to address the question {open_quotes}How safe is safe enough?{close_quotes} are reviewed and an attempt is made to apply the reasoning behind these approaches to the issue of acceptability of radiation exposures received in space. The approaches to the issue of the acceptability of technological risk described here are primarily analytical, and are drawn from examples in the management of environmental health risks. These include risk-based approaches, in which specific quantitative risk targets determine the acceptability of an activity, and cost-benefit and decision analysis, which generally focus on the estimation and evaluation of risks, benefits and costs, in a framework that balances these factors against each other. These analytical methods tend by their quantitative nature to emphasize the magnitude of risks, costs and alternatives, and to downplay other factors, especially those that are not easily expressed in quantitative terms, that affect acceptance or rejection of risk. Such other factors include the issues of risk perceptions and how and by whom risk decisions are made.

  15. Domain Approach: An Alternative Approach in Moral Education

    Science.gov (United States)

    Vengadasalam, Chander; Mamat, Wan Hasmah Wan; Mail, Fauziah; Sudramanian, Munimah

    2014-01-01

    This paper discusses the use of the domain approach in moral education in an upper secondary school in Malaysia. Moral Education needs a creative and an innovative approach. Therefore, a few forms of approaches are used in the teaching-learning of Moral Education. This research describes the use of domain approach which comprises the moral domain…

  16. Rail transport systems approach

    CERN Document Server

    2017-01-01

    This book shows how the systems approach is employed by scientists in various countries to solve specific problems concerning railway transport. In particular, the book describes the experiences of scientists from Romania, Germany, the Czech Republic, the UK, Russia, Ukraine, Lithuania and Poland. For many of these countries there is a problem with the historical differences between the railways. In particular, there are railways with different rail gauges, with different signaling and communication systems, with different energy supplies and, finally, with different political systems, which are reflected in the different approaches to the management of railway economies. The book’s content is divided into two main parts, the first of which provides a systematic analysis of individual means of providing and maintaining rail transport. In turn, the second part addresses infrastructure and management development, with particular attention to security issues. Though primarily written for professionals involved...

  17. A Personal Approach

    Directory of Open Access Journals (Sweden)

    Kellyn Weir

    2015-12-01

    Full Text Available This study explored the process of taking a personal approach to my son’s problems with computer games. As a psychology student, I should have been in a good position to explore the paradoxical emotions and this situation of conflict. Yet I was also aware that relating closely to the people we are studying has long been a taboo even in qualitative research. I nevertheless adopted a collaborative methodology in which I balanced a dual role of parent and researcher. Taking a personal approach, allowing intimate, reciprocal negotiation, I was not only able to put this taboo to the rare empirical test but also achieved an insight that would otherwise have not been available to me. By engaging in dialogue and encouraging the ability to object, a first-person plural (We, position was achieved in which an understanding of this situation developed and has transferred to our everyday lives.

  18. Sociocultural approach to textbook

    Directory of Open Access Journals (Sweden)

    Pešić Jelena M.

    2005-01-01

    Full Text Available The aim of this paper is to present an overview of textbook research at the Institute of psychology, intended to postulate socio-cultural approach to textbook. Shifting the textbook from classical pedagogical-psychological context into the broader and more inspiring cultural context, has led to the conceptualization of textbook as a cultural-supportive system of individual development. We consider firstly, the theoretical background of this conception, founded in Vygotskian idea of cultural mediation of development and then, its operationalization through the concept of cultural-supportive tools. The transfer from theory to practice is presented through the most important practical implications, such as defining the genre specificities of textbook and principles of educational design of textbooks. As a distinctive issue, we also consider the way this approach to textbook (theoretical articulation, analytical concepts, and practical implications contributes to development of socio-cultural paradigm in psychology.

  19. Thermodynamics an engineering approach

    CERN Document Server

    Cengel, Yunus A

    2014-01-01

    Thermodynamics, An Engineering Approach, eighth edition, covers the basic principles of thermodynamics while presenting a wealth of real-world engineering examples so students get a feel for how thermodynamics is applied in engineering practice. This text helps students develop an intuitive understanding by emphasizing the physics and physical arguments. Cengel and Boles explore the various facets of thermodynamics through careful explanations of concepts and use of numerous practical examples and figures, having students develop necessary skills to bridge the gap between knowledge and the confidence to properly apply their knowledge. McGraw-Hill is proud to offer Connect with the eighth edition of Cengel/Boles, Thermodynamics, An Engineering Approach. This innovative and powerful new system helps your students learn more efficiently and gives you the ability to assign homework problems simply and easily. Problems are graded automatically, and the results are recorded immediately. Track individual stude...

  20. Breakfast: a multidisciplinary approach

    OpenAIRE

    Affinita, Antonio; Catalani, Loredana; Cecchetto, Giovanna; De Lorenzo, Gianfranco; Dilillo, Dario; Donegani, Giorgio; Fransos, Lucia; Lucidi, Fabio; Mameli, Chiara; Manna, Elisa; Marconi, Paolo; Mele, Giuseppe; Minestroni, Laura; Montanari, Massimo; Morcellini, Mario

    2013-01-01

    Background The role of breakfast as an essential part of an healthy diet has been only recently promoted even if breakfast practices were known since the Middle Age. The growing scientific evidences on this topic are extremely sector-based nevertheless breakfast could be regarded from different point of views and from different expertises. This approach, that take into account history, sociology, anthropology, medicine, psychology and pedagogy, is useful to better understand the value of this...

  1. The Knowledge Governance Approach

    DEFF Research Database (Denmark)

    Foss, Nicolai

    2005-01-01

    An attempt is made to characterize a `knowledge governance approach' as a distinctive, emerging field that cuts across the fields of knowledge management, organisation studies, strategy and human resource management. Knowledge governance is taken up with how the deployment of administrative...... apparatus influences knowledge processes, such as sharing, retaining and creating knowledge. It insists on clear behavioural foundations, adopts an economizing perspective and examines efficient alignment between knowledge transactions with diverse characteristics and governance structures and mechanisms...

  2. The Branding Management Approaches

    Institute of Scientific and Technical Information of China (English)

    YAKOUBI; Mohamed Lamine

    2014-01-01

    [Abstract]We wil try to present,through the display of the various branding concepts and theories, the different branding management approaches.This wil present the different visions of the discipline depending on the author to try and demonstrate their differences,at first, and their complementarities at last to help the different branding management practitioners (brand managers,marketing managers,advertisers,media-planners……) apprehend the right brand positioning strategy to engage.

  3. Towards a Tectonic Approach

    DEFF Research Database (Denmark)

    Hvejsel, Marie Frier; Kirkegaard, Poul Henning; Mortensen, Sophie Bondgaard

    2015-01-01

    Given the increasing environmental and legislative demands to reduce energy consumption, not only new constructions but also the existing urban fabric is about to change radically in the coming decades. Existing buildings cannot simply be restored but must undergo a transformation to comply with ...... the building envelope as an aesthetic ‘gesture’, this paper discusses the architectural challenges related to energy renovation in a Danish context and tectonic design method as an approach to these challenges in everyday practice....

  4. APPROACHES FOR SUSTAINABLE MANUFACTURING

    Institute of Scientific and Technical Information of China (English)

    G(U)NTHER Seliger; SEBASTIAN Kernbaum; MARCO Zettl

    2007-01-01

    Sustainable development is a holistic approach harmonizing ecological, economical and socio-political needs with respect to the superior objective of enhancing human living standards. Thereby the availability of natural resources and the conservation of the ecosystems have to be considered that future generations have the possibility to meet their own needs. A long-term economical development demands the transition from a source-sink economy to a cycle economy as a result of limited resources, limited environmental capacities to absorb waste and emissions as well as increasing needs of a growing population. A reference model for sustainability in manufacturing is presented and used to illustrate sustainable approaches with respect to management, technology, process and product. Adaptation of products and components is a vital element for supporting efficient reuse of products and components. Consequently adaptation contributes to the ambitious goals of sustainability. Technological enablers for adaptation as modularity, information and communication technology are exemplarily introduced. Moreover, approaches for disseminating knowledge in sustainability are given.

  5. Multivariate Bioclimatic Ecosystem Change Approaches

    Science.gov (United States)

    2015-02-06

    conclude that an analogous patch did not exist. It must exist somewhere, but some of the other MVA techniques were restricted by the mathematical ...found that the Primarily Analogous Multivariate approach developed during this research clearly distinguished itself from the other five approaches in...Principally Analogous Multivariate (PAM) approach ............................................... 29 4.6.1 Introduction to the PAM approach

  6. A pH-and temperature-sensitive macrocyclic graft copolymer composed of PEO ring and multi-poly(2-(dimethylamino) ethyl methacrylate) lateral chains

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel method for the synthesis of macrocyclic graft copolymers was developed through combination of anionic ring-opening polymerization (AROP) and atom transfer radical polymerization (ATRP).A linear α,ω-dihydroxyl poly(ethylene oxide) with pendant acetal protected hydroxyl groups (l-poly(EO-co-EEGE)) was prepared first by the anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE).Then l-poly(EO-co-EEGE) was cyclized.The crude cyclized product containing the linear byproduct was hydrolyzed and purified by being treated with α-CD.The pure cyclic copolymer [c-poly(EO-co-Gly)] was esterified by reaction with 2-bromoisobutyryl bromide,and then used as ATRP macroinitiators to initiate polymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA),and a series of pH-and temperature-sensitive macrocyclic graft copolymers composed of a hydrophilic PEO as the ring and PDMAEMA as side chains (c-PEO-g-PDMAEMA) were obtained.The behavior of pH-and temperature-sensitive macrocyclic copolymers was studied in aqueous solution by fluorescence and dynamic light scattering (DLS).The critical micellization pH values of macrocyclic graft copolymers and their corresponding linear graft copolymers (l-PEO-g-PDMAEMA) were measured.Under the same conditions,the cyclic graft copolymer with the shorter side chains gave the higher critical micellization pH value.The c-PEO-g-PDMAEMA showed the lower critical micellization pH value than the corresponding l-PEO-g-PDMAEMA.The average hydrodynamic diameters (Dh) of the micelles were measured by DLS with the variation of the aqueous solution pH value and temperature.

  7. [Approaches to radial shaft].

    Science.gov (United States)

    Bartoníček, J; Naňka, O; Tuček, M

    2015-10-01

    In the clinical practice, radial shaft may be exposed via two approaches, namely the posterolateral Thompson and volar (anterior) Henry approaches. A feared complication of both of them is the injury to the deep branch of the radial nerve. No consensus has been reached, yet, as to which of the two approaches is more beneficial for the proximal half of radius. According to our anatomical studies and clinical experience, Thompson approach is safe only in fractures of the middle and distal thirds of the radial shaft, but highly risky in fractures of its proximal third. Henry approach may be used in any fracture of the radial shaft and provides a safe exposure of the entire lateral and anterior surfaces of the radius.The Henry approach has three phases. In the first phase, incision is made along the line connecting the biceps brachii tendon and the styloid process of radius. Care must be taken not to damage the lateral cutaneous nerve of forearm.In the second phase, fascia is incised and the brachioradialis identified by the typical transition from the muscle belly to tendon and the shape of the tendon. On the lateral side, the brachioradialis lines the space with the radial artery and veins and the superficial branch of the radial nerve running at its bottom. On the medial side, the space is defined by the pronator teres in the proximal part and the flexor carpi radialis in the distal part. The superficial branch of the radial nerve is retracted together with the brachioradialis laterally, and the radial artery medially.In the third phase, the attachment of the pronator teres is identified by its typical tendon in the middle of convexity of the lateral surface of the radial shaft. The proximal half of the radius must be exposed very carefully in order not to damage the deep branch of the radial nerve. Dissection starts at the insertion of the pronator teres and proceeds proximally along its lateral border in interval between this muscle and insertion of the supinator

  8. Peritonitis: laparoscopic approach

    Directory of Open Access Journals (Sweden)

    Agresta Ferdinando

    2006-03-01

    Full Text Available Abstract Background Laparoscopy has became as the preferred surgical approach to a number of different diseases because it allows a correct diagnosis and treatment at the same time. In abdominal emergencies, both components of treatment – exploration to identify the causative pathology and performance of an appropriate operation – can often be accomplished via laparoscopy. There is still a debate of peritonitis as a contraindication to this kind of approach. Aim of the present work is to illustrate retrospectively the results of a case-control experience of laparoscopic vs. open surgery for abdominal peritonitis emergencies carried out at our institution. Methods From January 1992 and January 2002 a total of 935 patients (mean age 42.3 ± 17.2 years underwent emergent and/or urgent surgery. Among them, 602 (64.3% were operated on laparoscopically (of whom 112 -18.7% – with peritonitis, according to the presence of a surgical team trained in laparoscopy. Patients with a history of malignancy, more than two previous major abdominal surgeries or massive bowel distension were not treated Laparoscopically. Peritonitis was not considered contraindication to Laparoscopy. Results The conversion rate was 23.2% in patients with peritonitis and was mainly due to the presence of dense intra-abdominal adhesions. Major complications ranged as high as 5.3% with a postoperative mortality of 1.7%. A definitive diagnosis was accomplished in 85.7% (96 pat. of cases, and 90.6% (87 of these patients were treated successfully by Laparoscopy. Conclusion Even if limited by its retrospective feature, the present experience let us to consider the Laparoscopic approach to abdominal peritonitis emergencies a safe and effective as conventional surgery, with a higher diagnostic yield and allows for lesser trauma and a more rapid postoperative recovery. Such features make Laparoscopy a challenging alternative to open surgery in the management algorithm for abdominal

  9. Mitochondrial diseases: therapeutic approaches.

    Science.gov (United States)

    DiMauro, Salvatore; Mancuso, Michelangelo

    2007-06-01

    Therapy of mitochondrial encephalomyopathies (defined restrictively as defects of the mitochondrial respiratory chain) is woefully inadequate, despite great progress in our understanding of the molecular bases of these disorders. In this review, we consider sequentially several different therapeutic approaches. Palliative therapy is dictated by good medical practice and includes anticonvulsant medication, control of endocrine dysfunction, and surgical procedures. Removal of noxious metabolites is centered on combating lactic acidosis, but extends to other metabolites. Attempts to bypass blocks in the respiratory chain by administration of electron acceptors have not been successful, but this may be amenable to genetic engineering. Administration of metabolites and cofactors is the mainstay of real-life therapy and is especially important in disorders due to primary deficiencies of specific compounds, such as carnitine or coenzyme Q10. There is increasing interest in the administration of reactive oxygen species scavengers both in primary mitochondrial diseases and in neurodegenerative diseases directly or indirectly related to mitochondrial dysfunction. Aerobic exercise and physical therapy prevent or correct deconditioning and improve exercise tolerance in patients with mitochondrial myopathies due to mitochondrial DNA (mtDNA) mutations. Gene therapy is a challenge because of polyplasmy and heteroplasmy, but interesting experimental approaches are being pursued and include, for example, decreasing the ratio of mutant to wild-type mitochondrial genomes (gene shifting), converting mutated mtDNA genes into normal nuclear DNA genes (allotopic expression), importing cognate genes from other species, or correcting mtDNA mutations with specific restriction endonucleases. Germline therapy raises ethical problems but is being considered for prevention of maternal transmission of mtDNA mutations. Preventive therapy through genetic counseling and prenatal diagnosis is

  10. Experimental approaches and applications

    CERN Document Server

    Crasemann, Bernd

    1975-01-01

    Atomic Inner-Shell Processes, Volume II: Experimental Approaches and Applications focuses on the physics of atomic inner shells, with emphasis on experimental aspects including the use of radioactive atoms for studies of atomic transition probabilities. Surveys of modern techniques of electron and photon spectrometry are also presented, and selected practical applications of inner-shell processes are outlined. Comprised of six chapters, this volume begins with an overview of the general principles underlying the experimental techniques that make use of radioactive isotopes for inner-sh

  11. The collaboratory approach

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, A.M.

    1997-04-01

    A {open_quotes}collaboratory{close_quotes} has been defined as a center without walls, in which researchers can perform their work without regard to geographical location. To an increasing degree, engineering design and development is also taking the form of far-flung collaborations among divisions of a plant, subcontractors, university consultants and customers. It has long been recognized that quality engineering education presents the student with an environment that duplicates as much as possible that which the graduate will encounter in industry. To that end, it is important that engineering schools begin to introduce the collaboratory approach in its preparation, and even use it in delivery of subject matter to students.

  12. [Regenerative approach for COPD].

    Science.gov (United States)

    Kubo, Hiroshi

    2011-10-01

    No treatment to cure of chronic obstructive pulmonary disease (COPD) is available. Regenerative medicine is one of promising areas for this intractable disease. Several reagents and growth factors are known to promote lung regeneration in small animal models. However, regenerative medicines for human lungs are not achieved yet. Recent advances in stem cell biology and tissue engineering have expanded our understanding of lung endogenous stem cells, and this new knowledge provides us with new ideas for future regenerative therapy for lung diseases. Although lungs are the most challenging organ for regenerative medicine, our cumulative knowledge of lung regeneration and of endogenous progenitor cells makes clear the possibilities for regenerative approach to COPD.

  13. Approaching Service Innovation Patterns

    Directory of Open Access Journals (Sweden)

    Andrea NAGY

    2013-06-01

    Full Text Available The present paper aims at analyzing the types of innovation in the field of services. First, the concept of innovation is defined and second, field literature is reviewed from the perspective of service innovation. The main types of innovation are identified based on several attempts at defining innovation, the most notable being Schumpeter’s. Thus, it is possible to approach concepts such as product and process innovation, incremental and radical innovation. Another aim has been to regard service innovation as a standout type of innovation.

  14. URBAN POLITICS: KEY APPROACHES

    Directory of Open Access Journals (Sweden)

    Ledyaeva Ol'ga Mikhaylovna

    2012-10-01

    Full Text Available Several approaches that underlie urban politics are discussed in the paper. They include neo-liberalism, political economy discourse, elitist/pluralist debates, and postmodernism. The neoliberal approach focuses on the limited role of the state and individual responsibility. The legal framework protects both the rights and responsibilities of individuals and regulates the operation of the market. It is the market that fosters individual choices and provides goods and services by virtue of the processes which are flexible, efficient and transparent. The political economy approaches (regulation theory, public choice theory, neo-Marxism explain urban politics via the analysis of national and international economic processes and changes in contemporary capitalism. Changes in national and international economies determine what solutions are possible. The discourse has been influenced by the debate on globalization of capital and labour markets. Modern elitism and neopluralism are represented by theories of "growth machines" and "urban regimes". The former focuses on bargaining alliances between political and business leaders in order to manage the urban system and to promote its growth. The latter develops neopluralist explanations of power within local communities with an emphasis on the fragmented nature of the government where local authorities lack comprehensive governing powers. Postmodernism views the city as the site of the crisis of late capitalism which leads to segregation of neighbourhoods onto prosperous areas and ghettoes. In contrast to the modern city, the postmodern city is not defined by its industrial base; rather, it is determined by its consumerist environment of malls and museums, characterized by revivalist architecture. At the same time, the suburban shopping mall and a motorway network make nonsense of the idea of the city as a unique and well-defined space. These and other approaches encompass a wide spectrum of possibilities

  15. Papilledema. An updated approach.

    Directory of Open Access Journals (Sweden)

    Yaney González Yglesias

    2009-07-01

    Full Text Available The term papilledema refers to the edema that appears in the optic papilla after intracranial hypertension. Some of its most frequent causes are intracranial lesions, hydrocephaly, thrombosis venous sinus and meningitis. The increase of intracranial tension is related with the results of the eye´s fundus examination, which are classified differently: incipient, established, chronic, and atrophic, depending on its severity or development. It is indispensable to carry out imaging tests before performing lumbar puncture. This article is an approach to the diagnosis and treatment of this gnoseological entity.

  16. [Cystic pyeloureteritis. Our approach].

    Science.gov (United States)

    Castillo Jimeno, J M; González de Garibay, A S; Ruiz Rubio, J L; Sebastián Borruel, J L

    1992-05-01

    We report a case of massive cystic pyeloureteritis that had been diagnosed by ureterorenoscopy in a patient with recurrent urinary infection and episodes of nephritic colic. The reports published in the literature indicate there is no specific treatment for this disease whose etiology is unknown. Its pathogenesis has not been well-established and it is difficult to distinguish from other urothelial filling defects. Although it has also been reported that it may progress to malignancy, we believe that the therapeutic approach should be conservative.

  17. Revitalizing the setting approach

    DEFF Research Database (Denmark)

    Bloch, Paul; Toft, Ulla; Reinbach, Helene Christine

    2014-01-01

    -based. Based on a presentation of ¿Health and Local Community¿, a supersetting initiative addressing the prevention of lifestyle diseases in a Danish municipality, the paper discusses the potentials and challenges of supporting local community interventions using the supersetting approach......BackgroundThe concept of health promotion rests on aspirations aiming at enabling people to increase control over and improve their health. Health promotion action is facilitated in settings such as schools, homes and work places. As a contribution to the promotion of healthy lifestyles, we have...

  18. Diagnostic approaches for cholangiocarcinoma

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cholangiocarcinomas arise from the epithelial cells of the bile ducts and are associated with poor prognosis. Despite new diagnostic approaches, the definite diagnosis of this malignancy continues to be challenging. Cholangiocarcinomas often grow longitudinally along the bile duct rather than in a radial direction. Thus, large tumor masses are frequently absent and imaging techniques, including ultrasound, CT, and MRI have only limited sensitivity. Tissue collection during endoscopic (ERCP) and/or percutaneous transhepatic (PTC) procedures are usually used to confirm a definitive diagnosis of cholangiocarcinoma. However, forceps biopsy and brush cytology provide positive results for malignancy in about only 50% of patients. Percutaneous and peroral cholangioscopy using fiber-optic techniques were therefore developed for direct visualization of the biliary tree, yielding additional information about endoscopic appearance and tumor extension, as well as a guided biopsy acquistion. Finally, endoscopic ultrasonography (EUS) complements endoscopic and percutaneous approaches and may provide a tissue diagnosis of tumors in the biliary region through fine- needle aspiration. In the future, new techniques allowing for early detection, including molecular markers, should be developed to improve the diagnostic sensitivity in this increasing tumor entity.

  19. Interstage Flammability Analysis Approach

    Science.gov (United States)

    Little, Jeffrey K.; Eppard, William M.

    2011-01-01

    The Interstage of the Ares I launch platform houses several key components which are on standby during First Stage operation: the Reaction Control System (ReCS), the Upper Stage (US) Thrust Vector Control (TVC) and the J-2X with the Main Propulsion System (MPS) propellant feed system. Therefore potentially dangerous leaks of propellants could develop. The Interstage leaks analysis addresses the concerns of localized mixing of hydrogen and oxygen gases to produce deflagration zones in the Interstage of the Ares I launch vehicle during First Stage operation. This report details the approach taken to accomplish the analysis. Specified leakage profiles and actual flammability results are not presented due to proprietary and security restrictions. The interior volume formed by the Interstage walls, bounding interfaces with the Upper and First Stages, and surrounding the J2-X engine was modeled using Loci-CHEM to assess the potential for flammable gas mixtures to develop during First Stage operations. The transient analysis included a derived flammability indicator based on mixture ratios to maintain achievable simulation times. Validation of results was based on a comparison to Interstage pressure profiles outlined in prior NASA studies. The approach proved useful in the bounding of flammability risk in supporting program hazard reviews.

  20. Approaches for Stereo Matching

    Directory of Open Access Journals (Sweden)

    Takouhi Ozanian

    1995-04-01

    Full Text Available This review focuses on the last decade's development of the computational stereopsis for recovering three-dimensional information. The main components of the stereo analysis are exposed: image acquisition and camera modeling, feature selection, feature matching and disparity interpretation. A brief survey is given of the well known feature selection approaches and the estimation parameters for this selection are mentioned. The difficulties in identifying correspondent locations in the two images are explained. Methods as to how effectively to constrain the search for correct solution of the correspondence problem are discussed, as are strategies for the whole matching process. Reasons for the occurrence of matching errors are considered. Some recently proposed approaches, employing new ideas in the modeling of stereo matching in terms of energy minimization, are described. Acknowledging the importance of computation time for real-time applications, special attention is paid to parallelism as a way to achieve the required level of performance. The development of trinocular stereo analysis as an alternative to the conventional binocular one, is described. Finally a classification based on the test images for verification of the stereo matching algorithms, is supplied.

  1. Modular Approach to Spintronics.

    Science.gov (United States)

    Camsari, Kerem Yunus; Ganguly, Samiran; Datta, Supriyo

    2015-06-11

    There has been enormous progress in the last two decades, effectively combining spintronics and magnetics into a powerful force that is shaping the field of memory devices. New materials and phenomena continue to be discovered at an impressive rate, providing an ever-increasing set of building blocks that could be exploited in designing transistor-like functional devices of the future. The objective of this paper is to provide a quantitative foundation for this building block approach, so that new discoveries can be integrated into functional device concepts, quickly analyzed and critically evaluated. Through careful benchmarking against available theory and experiment we establish a set of elemental modules representing diverse materials and phenomena. These elemental modules can be integrated seamlessly to model composite devices involving both spintronic and nanomagnetic phenomena. We envision the library of modules to evolve both by incorporating new modules and by improving existing modules as the field progresses. The primary contribution of this paper is to establish the ground rules or protocols for a modular approach that can build a lasting bridge between materials scientists and circuit designers in the field of spintronics and nanomagnetics.

  2. SYNTHESIS OF NEW TREN-BASED LIGANDS AND THE ACTIVITY OF RESULTING COPPER COMPLEXES IN ATRP. (R829580)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  3. Advanced intelligence and mechanism approach

    Institute of Scientific and Technical Information of China (English)

    ZHONG Yixin

    2007-01-01

    Advanced intelligence will feature the intelligence research in next 50 years.An understanding of the concept of advanced intelligence as well as its importance will be provided first,and detailed analysis on an approach,the mechanism approach.suitable to the advanced intelligence research will then be flolowed.And the mutual relationship among mechanism approach,traditional approaches existed in artificial intelligence research,and the cognitive informatics will be discussed.It is interesting to discover that mechanism approach is a good one to the Advanced Intelligence research and a tmified form of the existed approaches to artificial intelligence.

  4. The Point Approach and the Phrase Approach to Vocabulary Learning

    Institute of Scientific and Technical Information of China (English)

    刘梦媛

    2013-01-01

      As is known to all, vocabulary acquisition plays an essential role in English learning. However, it was supposed very dif⁃ficult to many Chinese learners. For the reason that so many kinds of approaches exists in the real life, English learners are always do not know which one is suitable and more effective. To solve this problem, the paper will analyze two approaches (point approach and phrase approach) for you.

  5. Integration a functional approach

    CERN Document Server

    Bichteler, Klaus

    1998-01-01

    This book covers Lebesgue integration and its generalizations from Daniell's point of view, modified by the use of seminorms. Integrating functions rather than measuring sets is posited as the main purpose of measure theory. From this point of view Lebesgue's integral can be had as a rather straightforward, even simplistic, extension of Riemann's integral; and its aims, definitions, and procedures can be motivated at an elementary level. The notion of measurability, for example, is suggested by Littlewood's observations rather than being conveyed authoritatively through definitions of (sigma)-algebras and good-cut-conditions, the latter of which are hard to justify and thus appear mysterious, even nettlesome, to the beginner. The approach taken provides the additional benefit of cutting the labor in half. The use of seminorms, ubiquitous in modern analysis, speeds things up even further. The book is intended for the reader who has some experience with proofs, a beginning graduate student for example. It might...

  6. Editorial: Approaching 125.

    Science.gov (United States)

    Goodman, Sherryl

    2012-02-01

    With this issue, beginning Volume 121, the editorial team shifts from the strong leadership of David Watson to a team under my direction. Approaching 125 years of publication, the Journal of Abnormal Psychology has earned its place as the preeminent outlet for research in psychopathology. With gratitude to the newly assembled team of associate editors (AEs), consulting editors, and ad hoc reviewers, I look forward to guiding the journal through this next term. Nine well-respected scholars have agreed to serve as AEs: Timothy Brown, Laurie Chassin, Jeff Epstein, Jutta Joormann, Pamela Keel, Kate Keenan, Scott Lilienfeld, Angus MacDonald, and Michael Young. The new team is dedicated to working tirelessly to maintain and enhance the journal's esteemed tradition of excellence. Given the well-established strengths of the journal, I will not suggest any fundamental changes.

  7. Towards a Dual Approach

    DEFF Research Database (Denmark)

    Holli, Anne Maria; Harder, Mette Marie Stæhr

    2016-01-01

    countries acknowledged as forerunners in gender equality, which also have ‘fairly strong’ parliamentary standing committees. The results show that both committees on gender equality can be regarded as ‘feminist’ in character and both interact with relevant civil society organisations. Their impact......Drawing on insights from state feminism and legislative studies on parliamentary committees, this article develops a dual approach for the comparative analysis of committees on gender equality. Empirically, it compares the standing committees on gender equality in Denmark and Finland, two Nordic...... as measured by legislative outputs and oversight differs, however, in line with differing committee system characteristics: the Finnish committee has more impact on legislative outputs while the Danish committee has more impact on overseeing government....

  8. Material Modelling - Composite Approach

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1997-01-01

    , and internal stresses caused by drying shrinkage with experimental results reported in the literature on the mechanical behavior of mature concretes. It is then concluded that the model presented applied in general with respect to age at loading.From a stress analysis point of view the most important finding......This report is part of a research project on "Control of Early Age Cracking" - which, in turn, is part of the major research programme, "High Performance Concrete - The Contractor's Technology (HETEK)", coordinated by the Danish Road Directorate, Copenhagen, Denmark, 1997.A composite......-rheological model of concrete is presented by which consistent predictions of creep, relaxation, and internal stresses can be made from known concrete composition, age at loading, and climatic conditions. No other existing "creep prediction method" offers these possibilities in one approach.The model...

  9. Therapeutic approaches for shankopathies.

    Science.gov (United States)

    Wang, Xiaoming; Bey, Alexandra L; Chung, Leeyup; Krystal, Andrew D; Jiang, Yong-Hui

    2014-02-01

    Despite recent advances in understanding the molecular mechanisms of autism spectrum disorders (ASD), the current treatments for these disorders are mostly focused on behavioral and educational approaches. The considerable clinical and molecular heterogeneity of ASD present a significant challenge to the development of an effective treatment targeting underlying molecular defects. Deficiency of SHANK family genes causing ASD represent an exciting opportunity for developing molecular therapies because of strong genetic evidence for SHANK as causative genes in ASD and the availability of a panel of Shank mutant mouse models. In this article, we review the literature suggesting the potential for developing therapies based on molecular characteristics and discuss several exciting themes that are emerging from studying Shank mutant mice at the molecular level and in terms of synaptic function.

  10. [Orthopedic approach to asymmetry].

    Science.gov (United States)

    Bardinet, Etienne; Duhart, Anne-Marie

    2002-06-01

    Asymmetry being a clinical manifestation of various pathologies, the orthopedic attitude greatly varies from one practitioner to another. Thanks to a better knowledge of the etiopathogenesis, the orthopedic approach in some particular cases reveals very effective, either alone or together with other therapeutics. In mandibular laterodeviations most often consecutive to a maxillary contraction, the best treatment is to expand maxilla which will allow a mandibular centric repositioning. This therapy is often achieved early to limit the asymmetric expression of growth and normalize the dental eruption. In unilateral condylar hypoplasias of variable extension, from a simple defect in condylar growth to a hemifacial microsomia, the therapeutic attitude has mostly evolved. A surgical orthodontic protocol can integrate an increasingly significant orthopedic phase in the course of time. Some authors show that a surgical case may be treated originally only with the help of orthopedics. The devices used are of activator or hyperpropulsor type. In unilateral condylar hyperplasias, orthopedic therapy must be considered with reservations.

  11. Microscopic approach to polaritons

    DEFF Research Database (Denmark)

    Skettrup, Torben

    1981-01-01

    contrary to experimental experience. In order to remove this absurdity the semiclassical approach must be abandoned and the electromagnetic field quantized. A simple microscopic polariton model is then derived. From this the wave function for the interacting exciton-photon complex is obtained...... zero while the polarization field per polariton is essentially the excitonic dipole moment per unit volume. From the wave function of the polariton it is seen that in a very broad spectral range around the resonance the polariton is essentially an exciton that travels through the crystal with the speed...... of light of the crystal. The introduction of damping smears out the excitonic spectra. The wave function of the polariton, however, turns out to be very independent of damping up to large damping values. Finally, this simplified microscopic polariton model is compared with the exact solutions obtained...

  12. Bioengineering a conceptual approach

    CERN Document Server

    Pavlovic, Mirjana

    2015-01-01

    This book explores critical principles and new concepts in bioengineering, integrating the biological, physical and chemical laws and principles that provide a foundation for the field. Both biological and engineering perspectives are included, with key topics such as the physical-chemical properties of cells, tissues and organs; principles of molecules; composition and interplay in physiological scenarios; and the complex physiological functions of heart, neuronal cells, muscle cells and tissues. Chapters evaluate the emerging fields of nanotechnology, drug delivery concepts, biomaterials, and regenerative therapy. The leading individuals and events are introduced along with their critical research. Bioengineering: A Conceptual Approach is a valuable resource for professionals or researchers interested in understanding the central elements of bioengineering. Advanced-level students in biomedical engineering and computer science will also find this book valuable as a secondary textbook or reference.

  13. Slurry pipeline design approach

    Energy Technology Data Exchange (ETDEWEB)

    Betinol, Roy; Navarro R, Luis [Brass Chile S.A., Santiago (Chile)

    2009-12-19

    Compared to other engineering technologies, the design of a commercial long distance Slurry Pipeline design is a relatively new engineering concept which gained more recognition in the mid 1960 's. Slurry pipeline was first introduced to reduce cost in transporting coal to power generating units. Since then this technology has caught-up worldwide to transport other minerals such as limestone, copper, zinc and iron. In South America, the use of pipeline is commonly practiced in the transport of Copper (Chile, Peru and Argentina), Iron (Chile and Brazil), Zinc (Peru) and Bauxite (Brazil). As more mining operations expand and new mine facilities are opened, the design of the long distance slurry pipeline will continuously present a commercially viable option. The intent of this paper is to present the design process and discuss any new techniques and approach used today to ensure a better, safer and economical slurry pipeline. (author)

  14. Management practice: phenomenological approach

    Directory of Open Access Journals (Sweden)

    Myriam Siqueira da Cunha

    2005-01-01

    Full Text Available This work has the aim of understanding the lived experiences by managers in relation to organizational changes in an enterprise in the food area, located in the State of Rio Grande do Sul, Brazil. The role of managers has been constantly evaluated and their capacity of continuous learning and also the ability of transforming the learning in good organizational results is reacquired every instant. In this work, my intention is to show, using an interpretative analysis, real and practical situations, from lived experiences. The methodological way followed was the hermeneutic phenomenological approach, trying to give a global and a contextual treatment to the theme. The results achieved offer subsides for a new look over the management practice and point out the importance of the study of what is lived, as an inspiration source for the strategic decisions in the enterprises.

  15. Approaching attometer laser vibrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rembe, Christian; Kadner, Lisa; Giesen, Moritz [Research and Development, Polytec GmbH, Polytec Platz 1-7, 76337 Waldbronn (Germany)

    2014-05-27

    The heterodyne two-beam interferometer has been proven to be the optimal solution for laser-Doppler vibrometry regarding accuracy and signal robustness. The theoretical resolution limit for a two-beam interferometer of laser class 3R (up to 5 mW visible measurement-light) is in the regime of a few femtometer per square-root Hertz and well suited to study vibrations in microstructures. However, some new applications of RF-MEM resonators, nanostructures, and surface-nano-defect detection require resolutions beyond that limit. The resolution depends only on the noise and the sensor sensitivity to specimen displacements. The noise is already defined in nowadays systems by the quantum nature of light for a properly designed optical sensor and more light would lead to an inacceptable influence like heating of a very tiny structure. Thus, noise can only be improved by squeezed-light techniques which require a negligible loss of measurement light which is impossible for almost all technical measurement tasks. Thus, improving the sensitivity is the only possible path which could make attometer laser vibrometry possible. Decreasing the measurement wavelength would increase the sensitivity but would also increase the photon shot noise. In this paper, we discuss an approach to increase the sensitivity by assembling an additional mirror between interferometer and specimen to form an optical cavity. A detailed theoretical analysis of this setup is presented and we derive the resolution limit, discuss the main contributions to the uncertainty budget, and show a first experiment proving the sensitivity amplification of our approach.

  16. SOME REFLECTIONS ON STRUCTURAL APPROACH

    Institute of Scientific and Technical Information of China (English)

    GuiQingyang

    1997-01-01

    The present paper is intended to expound the advantages and disadvantages of the trathtional Structural Approach in the Chinese context and discuss the necessity and feasibility of implementing the Communicative Approach and the Self--service Approach,both of which evaluate highly the position of subjective activity in learning and bring the obligation of professional development back to learners themselves,KEY WORD approach structural communicative self service critique adaptadopt

  17. A Narrative Approach to Research

    Science.gov (United States)

    Bell, Anne

    2003-01-01

    In this paper I present a narrative approach to environmental education research. This approach evolved through a dynamic interplay between research questions, theory, experience, conversation, and reflection. I situate the approach with respect to narrative inquiry and clarify the key conceptual metaphors underpinning my study, including…

  18. Approach focused on people

    Directory of Open Access Journals (Sweden)

    Roa Ruben

    2010-11-01

    Full Text Available Family and community medicine assumes a new epistemological landmark that also provides the use of instruments and tools related to it. This care model permits carrying out a visit where all categories which the health-disease process is expressed are present. Family Medicine intends to combine both visions and, for such, it gifts elements to incorporate disease as an essential part of our patient's approach systematic being the main focus the approach by problems, which is nothing but that which concerns the individual, his family or the physician, or all of them, and at times there will be nuisances while at other times, there will be diseases, and mil in other instances, all of them will co-exist. It is known that the impact of a health problem on an individual affects not only himself, but also his surroundings. In turn, the environment around this individual can act as the origin or perpetuator of the crisis, or else serve to help in solving the conflict. Distinct tools serve the purpose of knowing the context in which health crisis is developed, such as: genogram, individual and family vital cycle. Every time two people communicate, the agreement or disagreement generate possible variables. In the physician-patient relationship, this is no exception. Values, beliefs, feelings, and information of each individual different and physicians not necessarily in agreement in several issues during a visit. The objective is the need to achieve a minimum of agreements so that this visit has therapeutic effectiveness, thus being if/rpm -taw to find a common territory. Relations in general involve power; care, feelings, trust and goals. The objective in this type of relationship must be obviously shared ly both and cannot be any other than that of achieving, the highest level of health to our patient. So, our specialty, considered of low complexity, becomes a highly cognitive complexity, special and there is no doubt that it is a lot easier to handle

  19. APPROACH TO ORGANIC ACIDEMIA

    Directory of Open Access Journals (Sweden)

    Gholamreza ZAMANI

    2012-03-01

    Full Text Available Organic acidemias, also known as organic acidurias, are a group of disorders characterized by increased excretion of organic acids in urine. They result primarily from deficiencies of specific enzymes in the breakdown pathways of amino acids or from enzyme deficiencies in beta oxidation of fatty acids or carbohydrate metabolism. Organic acids also are found in the urine of some patients with mitochondrial disease.Most organic acidemias become clinically apparent during the newborn period or early infancy. After an initial period of well-being, affected children develop a life-threatening episode of metabolic acidosis characterized by an increased anion gap. This presenting episode may be mistaken for sepsis, and if unrecognized, is associated with significant mortality.Children with an organic acidemia are susceptible to metabolic decompensation during episodes of increased catabolism, such as intercurrent illness, trauma, or surgery. Parents and clinicians must be well informed about the initial signs of decompensation and trained in applying an emergency regimen . Surgeons and anesthesiologists should be aware of potential complications and their prevention during anesthesia and surgery.Diagnosis has been facilitated through the use of gas chromatograph-mass spectrometry (GC-MS and tandem mass spectrometry .Prenatal diagnosis is available for most disorders by detection of diagnostic compounds in amniotic fluid; by analysis of enzyme activities in amniocytes or chorionic villi; by molecular analysis; or by a combination of the three . Diagnosis also may be made through newborn screening by tandem mass spectrometry .Laboratory findings are an essential part of the diagnostic approach to organic acidemias. In most organic acidemias, metabolism of glucose, ketone bodies, and ammonia is deranged primarily or secondarily, in addition to derangement of the acid-base balance. Hypoglycemia, lactic and/or ketoacidosis, and hyperammonemia of varying

  20. DMFC Performance of Polymer Electrolyte Membranes Prepared from a Graft-Copolymer Consisting of a Polysulfone Main Chain and Styrene Sulfonic Acid Side Chains

    Directory of Open Access Journals (Sweden)

    Nobutaka Endo

    2016-08-01

    Full Text Available Polymer electrolyte membranes (PEMs for direct methanol fuel cell (DMFC applications were prepared from a graft-copolymer (PSF-g-PSSA consisting of a polysulfone (PSF main chain and poly(styrene sulfonic acid (PSSA side chains with various average distances between side chains (Lav and side chain lengths (Lsc. The polymers were synthesized by grafting ethyl p-styrenesulfonate (EtSS on macro-initiators of chloromethylated polysulfone with different contents of chloromethyl (CM groups, and by changing EtSS content in the copolymers by using atom transfer radical polymerization (ATRP. The DMFC performance tests using membrane electrode assemblis (MEAs with the three types of the PEMs revealed that: a PSF-g-PSSA PEM (SF-6 prepared from a graft copolymer with short average distances between side chains (Lav and medium Lsc had higher DMFC performance than PEMs with long Lav and long Lsc or with short Lav and short Lsc. SF-6 had about two times higher PDmax (68.4 mW/cm2 than Nafion® 112 at 30 wt % of methanol concentration. Furthermore, it had 58.2 mW/cm2 of PDmax at 50 wt % of methanol concentration because of it has the highest proton selectivity during DMFC operation of all the PSF-g-PSSA PEMs and Nafion® 112.

  1. New poly(dimethylsiloxane)/poly(perfluorooctylethyl acrylate) block copolymers: structure and order across multiple length scales in thin films

    KAUST Repository

    Martinelli, Elisa

    2011-01-01

    Three sets of a new class of low surface tension block copolymers were synthesized consisting of a poly(dimethylsiloxane) (PDMS) block and a poly(perfluorooctylethyl acrylate) (AF8) block. The polymers were prepared using a bromo-terminated PDMS macroinitiator, to which was attached an AF8 block grown using atom transfer radical polymerization (ATRP) in such a designed way that the molecular weight and composition of the two polymer blocks were regularly varied. The interplay of both the phase separated microstructure and the mesomorphic character of the fluorinated domains with their effect on surface structure was evaluated using a suite of analytical tools. Surfaces of spin-coated and thermally annealed films were assessed using a combination of X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) studies. Both atomic force microscopy (AFM) measurements and grazing incidence small angle X-ray scattering (GISAXS) studies were carried out to evaluate the microstructure of the thin films. Even in block copolymers in which the PDMS block was the majority component, a significant presence of the lower surface energy AF8 block was detected at the film surface. Moreover, the perfluorooctyl helices of the AF8 repeat units were highly oriented at the surface in an ordered, tilted smectic structure, which was compared with those of the bulk powder samples using wide-angle X-ray powder diffraction (WAXD) studies. © 2011 The Royal Society of Chemistry.

  2. Drug release property of a pH-responsive double-hydrophilic hyperbranched graft copolymer

    Institute of Scientific and Technical Information of China (English)

    SUN XiaoYi; ZHOU YongFeng; YAN DeYue

    2009-01-01

    In this paper, we report the synthesis and self-assembly of double-hydrophilie hyperbranched graft copolymers of HPG-g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG-g-PDMAEMA graft copolymers through atom transfer radical polymerization (ATRP) of DMAEMA monomers. The molecular structures were studied by 1H NMR arid GPC. The pyrene-based fluorescent probe method, 1H NMR and DLS were used to study the self-assembly behavior of HPG-g-PDMAEMA. The drug loading and pH-responsive release properties of HPG-g-PDMAEMA were also investigated by using coumarin 102 as a model drug. The results show that the HPG-g-PDMAEMA micelles can continuously release and re-encapsulate coumarin 102 as the pH continuously changes from 11.5 to 2.5; however, this process is not totally reversible.

  3. Drug release property of a pH-responsive double-hydrophilic hyperbranched graft copolymer

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, we report the synthesis and self-assembly of double-hydrophilic hyperbranched graft copolymers of HPG-g-PDMAEMA, which consist of a hyperbranched polyglycerol (HPG) core and several grafted poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) arms. HPG was synthesized by cationic polymerization. Then HPG-Br macroinitiator was obtained by esterification of HPG with 2-bromoisobutyryl bromide, which was subsequently used in the preparation of HPG-g-PDMAEMA graft copolymers through atom transfer radical polymerization (ATRP) of DMAEMA monomers. The molecular structures were studied by 1H NMR and GPC. The pyrene-based fluorescent probe method, 1H NMR and DLS were used to study the self-assembly behavior of HPG-g-PDMAEMA. The drug loading and pH-responsive release properties of HPG-g-PDMAEMA were also investigated by using coumarin 102 as a model drug. The results show that the HPG-g-PDMAEMA micelles can continuously release and re-encapsulate coumarin 102 as the pH continuously changes from 11.5 to 2.5; however, this process is not totally reversible.

  4. Supramolecular self-assembly and controllable drug release of thermosensitive hyperbranched multiarm copolymers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel temperature-responsive hyperbranched multiarm copolymer with a hydrophobic hyperbranched poly(3-ethyl-3-(hydroxymethyl)oxetane)(HBPO) core and thermosensitive poly(N-isopropylacrylamide)(PNIPAM) arms was synthesized via the atom transfer radical polymerization(ATRP) of NIPAM monomers from a hyperbranched HBPO macroinitiator.It was found that HBPO-star-PNIPAM self-assembled into multimolecular micelles(around 60 nm) in water at room temperature according to pyrene probe fluorescence spectrometry,1H NMR,TEM,and DLS measurements.The micelle solution showed a reversible thermosensitive phase transition at a lower critical solution temperature(LCST)(around 32°C) observed by variable temperature optical absorbance measurements.Variable temperature NMR and DLS analyses demonstrated that the LCST transition originated from the secondary aggregation of the micelles driven by increasing hydrophobic interaction due to the dehydration of PNIPAM shells upon heating.The drug loading and release properties of HBPO-star-PNIPAM micelles were also investigated using prednisone acetate as a model drug.The micelles showed a much improved drug encapsulation efficiency and temperature-dependent sustainable release behavior due to the special micellar structure.The micelles exhibited no apparent cytotoxicity against human HeLa cells.

  5. Synthesis and aqueous solution properties of novel sugar methacrylate-based homopolymers and block copolymers.

    Science.gov (United States)

    Narain, Ravin; Armes, Steven P

    2003-01-01

    We report the facile preparation of a range of novel, well-defined cyclic sugar methacrylate-based polymers without recourse to protecting group chemistry. 2-Gluconamidoethyl methacrylate (GAMA) and 2-lactobionamidoethyl methacrylate (LAMA) were prepared directly by reacting 2-aminoethyl methacrylate with D-gluconolactone and lactobionolactone, respectively. Homopolymerization of GAMA and LAMA by atom transfer radical polymerization (ATRP) gave reasonably low polydispersities as judged by aqueous gel permeation chromatography. A wide range of sugar-based block copolymers were prepared using near-monodisperse macroinitiators based on poly(ethylene oxide) [PEO], poly(propylene oxide) [PPO], or poly(e-caprolactone) [PCL] and/or by sequential monomer addition of other methacrylic monomers such as 2-(diethylamino)ethyl methacrylate [DEA], 2-(diisopropylaminoethyl methacrylate [DPA], or glycerol monomethacrylate [GMA]. The reversible micellar self-assembly of selected sugar-based block copolymers [PEO23-GAMA50-DEA100, PEO23-LAMA30-DEA50, PPO33-GAMA50, and PPO33-LAMA50] was studied in aqueous solution as a function of pH and temperature using dynamic light scattering, transmission electron microscopy, surface tensiometry, and 1H NMR spectroscopy.

  6. Text Steganographic Approaches: A Comparison

    Directory of Open Access Journals (Sweden)

    Monika Agarwal

    2013-02-01

    Full Text Available This paper presents three novel approaches of text steganography. The first approach uses the theme ofmissing letter puzzle where each character of message is hidden by missing one or more letters in a wordof cover. The average Jaro score was found to be 0.95 indicating closer similarity between cover andstego file. The second approach hides a message in a wordlist where ASCII value of embedded characterdetermines length and starting letter of a word. The third approach conceals a message, withoutdegrading cover, by using start and end letter of words of the cover. For enhancing the security of secretmessage, the message is scrambled using one-time pad scheme before being concealed and cipher text isthen concealed in cover. We also present an empirical comparison of the proposed approaches with someof the popular text steganographic approaches and show that our approaches outperform the existingapproaches.

  7. Approaches to refractory epilepsy

    Directory of Open Access Journals (Sweden)

    Jerome Engel

    2014-01-01

    Full Text Available Epilepsy is one of the most common serious neurological conditions, and 30 to 40% of people with epilepsy have seizures that are not controlled by medication. Patients are considered to have refractory epilepsy if disabling seizures continue despite appropriate trials of two antiseizure drugs, either alone or in combination. At this point, patients should be referred to multidisciplinary epilepsy centers that perform specialized diagnostic testing to first determine whether they are, in fact, pharmacoresistant, and then, if so, offer alternative treatments. Apparent pharmacoresistance can result from a variety of situations, including noncompliance, seizures that are not epileptic, misdiagnosis of the seizure type or epilepsy syndrome, inappropriate use of medication, and lifestyle issues. For patients who are pharmacoresistant, surgical treatment offers the best opportunity for complete freedom from seizures. Surgically remediable epilepsy syndromes have been identified, but patients with more complicated epilepsy can also benefit from surgical treatment and require more specialized evaluation, including intracranial EEG monitoring. For patients who are not surgical candidates, or who are unwilling to consider surgery, a variety of other alternative treatments can be considered, including peripheral or central neurostimulation, ketogenic diet, and complementary and alternative approaches. When such alternative treatments are not appropriate or effective, quality of life can still be greatly improved by the psychological and social support services offered by multidisciplinary epilepsy centers. A major obstacle remains the fact that only a small proportion of patients with refractory epilepsy are referred for expert evaluation and treatment.

  8. Halitosis: the multidisciplinary approach.

    Science.gov (United States)

    Bollen, Curd M L; Beikler, Thomas

    2012-06-01

    Halitosis, bad breath or oral malodour are all synonyms for the same pathology. Halitosis has a large social and economic impact. For the majority of patients suffering from bad breath, it causes embarrassment and affects their social communication and life. Moreover,halitosis can be indicative of underlying diseases. Only a limited number of scientific publications were presented in this field until 1995. Ever since, a large amount of research is published, often with lack of evidence. In general, intraoral conditions, like insufficient dental hygiene, periodontitis or tongue coating are considered to be the most important cause (85%) for halitosis. Therefore, dentists and periodontologists are the first-line professionals to be confronted with this problem. They should be well aware of the origin, the detection and especially of the treatment of this pathology. In addition, ear-nose-throat-associated (10%) or gastrointestinal/endocrinological (5%) disorders may contribute to the problem. In the case of halitophobia, psychiatrical or psychological problems may be present. Bad breath needs a multidisciplinary team approach: dentists, periodontologists, specialists in family medicine, ear-nose-throat surgeons, internal medicine and psychiatry need to be updated in this field, which still is surrounded by a large taboo.Multidisciplinary bad breath clinics offer the best environment to examine and treat this pathology that affects around 25% of the whole population. This article describes the origin, detection and treatment of halitosis, regarded from the different etiological origins.

  9. APPROACHES TO PUBLIC INTEGRITY

    Directory of Open Access Journals (Sweden)

    Simona-Roxana ULMAN

    2015-08-01

    Full Text Available Both concepts, integrity and public integrity, are always asked qualities in the social and economic environment, but they are never well defined. In this context, finding precise definitions and offering an ample explanation of the concepts are desired and useful for both economic theoretical and practical levels and become the aim of the present paper. Without a good understanding of a concept, no one is capable to attain it. In this context, it is impossible to ask for a public sector of integrity if both public actors and the citizens do not know what it really means. Therefore, the public actors first have to understand what integrity really supposes, and, then, to be capable to respect its principles. Taking into consideration the effects of public integrity or, on its opposite, of the divergence from it, especially represented by the phenomenon of corruption, on the economy at the macro, but also, on the micro level, public integrity in itself becomes a real economic problem that is aimed to be extensively analyzed through our interdisciplinary approach.

  10. The Community Reinforcement Approach.

    Science.gov (United States)

    Meyers, Robert J; Smith, Jane Ellen; Lash, Denise N

    2003-01-01

    This chapter reviews two behavioral substance abuse treatments: The Community Reinforcement Approach (CRA) and Community Reinforcement and Family Training (CRAFT). Both of these programs were built on the concept that an individual's recovery is greatly affected by his or her unique environment. This environment, or reinforcing "community," is composed of family, friends, work/school, social activities, and perhaps spiritual affiliations. CRA, the first of these two programs to be developed, was created specifically for the problem drinker (Hunt & Azrin, 1973). The goal of CRA is to rearrange multiple aspects of an individual's "community" so that a clean and sober lifestyle is more rewarding than one that is dominated by alcohol and drugs. Subsequently, CRAFT was developed for the many individuals with substance abuse problems who are vehemently opposed to treatment (Institute of Medicine, 1990). CRAFT works through concerned family members and friends of these treatment refusers in an effort to get them to seek therapy (Sisson & Azrin, 1986). Descriptions and the empirical support for CRA and CRAFT follow.

  11. Design, Synthesis and Characterization of Polyethylene-Based Macromolecular Architectures by Combining Polyhomologation with Powerful Linking Chemistry

    KAUST Repository

    Alkayal, Nazeeha

    2016-09-05

    -based graft terpolymers were synthesized via the “grafting onto” strategy by combining nitroxide-mediated radical polymerization (NMP), polyhomologation and copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC). Three steps were involved in this approach: (a) synthesis of alkyne-terminated polyethylene-b-poly(ε-caprolactone) (PE-b-PCL-alkyne) block copolymers (branches) by esterification of PE-b-PCL-OH with 4-pentynoic acid; the PE-b-PCL-OH was obtained by polyhomologation of dimethylsulfoxonium methylide to afford PE-OH, followed by ring opening polymerization of ε-caprolactone using PE-OH as a macroinitiator (b) synthesis of random copolymers of styrene (St) and 4-chloromethylstyrene (4-CMS) with various CMS contents, by nitroxide-mediated radical copolymerization (NMP), and conversion of chloride to azide groups by reaction with sodium azide (NaN3) (backbone) and (c) “click” linking reaction to afford the PE-based graft terpolymers. This method opens up new routes for the creation of polyethylene-based graft terpolymers by a combination of polyhomologation, NMP and CuAAC. The third project deals with the synthesis of polyethylene-based tadpole copolymer (c-PE)-b-PSt. Cyclic polymers represent a class of understudied polymer architecture mainly due to the synthetic challenges. Within this dissertation, a new method was reported for the synthesis of cyclic polymers in exceptionally high purity and yield. The main approaches to synthesize macrocycles are based on the end-to-end ring-closure (coupling) of homo difunctional linear precursors under high dilution. Our process relies on the preparation of well-defined linear α, ω-dihydroxy polyethylene and a bromide group at the middle of the chain through polyhomologation of ylide using functionalized initiator, followed by ATRP of styrene monomer. The two hydroxyl groups were transformed into alkyne groups, via esterification reaction, followed by Glaser reaction between terminal alkynes to afford the tadpole

  12. Radiolab - three different approaches

    Directory of Open Access Journals (Sweden)

    Ola Stockfelt

    2012-04-01

    Full Text Available The three papers in this ‘suite’ have a special background and context. At the 2010 conference SoundActs in Aarhus the three panellists were each given the task to provide a paper with an analysis of the same sound object, thus exhibiting and contrasting different scholarly approaches to sound studies. The object was selected by Torben Sangild, who was familiar with the chosen context: the signature of the US radio programme and podcast Radiolab. The two other participants did not know the context and chose to analyse the sound object without further contextual investigation. This object was chosen for several reasons. First of all, it is brief (less than 17 seconds, which meant that it was possible to make a detailed analysis; at the same time, though, it is relatively complex, which means that it can accommodate three different analyses. It is a sound object with a global audience, taken from one of the most popular podcasts worldwide, accessible on the internet. Finally, it is a piece of functional sound design, rather than a work of art, which raises the question of context more clearly. The result is three rather different approaches: 1 a process analysis, observing analytical listening strategies towards the constructed object, 2 a vocal analysis, regarding the sound object as a polyphony of voices, and 3 a contextual analysis, framing the sound object as a radio signature. Ola Stockfelt analyses the sound object as something that is constructed via his own repeated listening process – as a scholarly-analytical analysis of the subjective act of creating meaning. He draws on presumptions and prejudices, demonstrating the impossibility of a purely structural listening. The analysis relates these hermeneutical reflections to formal musicological observations of harmony, timbre, space and rhythm in some detail. Ansa Lønstrup’s paper analyses the sound object as a polyphony of voices. Her analysis is inspired by two phenomenologists

  13. Constructional Approach as Compared with Projectionist Approach to Argument Structure

    Institute of Scientific and Technical Information of China (English)

    戴好运

    2016-01-01

    Projectionist accounts of argument structure give verb's semantic representation a central role in sentence interpretation, it is held that the argument structure and alternations related with a verb are always the product of its semantic representation. However, a circularity problem arises. To solve this problem, Goldberg (1995)'s constructional approach proposed that argument structure patterns are linguistic units in their own right. This paper attempts to make a comparison between projectionist approach and constructional approach to argument structure and discuss constructional approach's advantage in reducing verb senses and avoiding circularity.

  14. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  15. 以纤维素为模板制备多孔SiO2棒%Synthesis of Mesoporous Silica Nanorod by Using the Cellulose as Template

    Institute of Scientific and Technical Information of China (English)

    张奎; 刘春华; 王平华; 范保林; 屈龙

    2011-01-01

    以2-溴丁酰溴与羟乙基纤维素的酯化产物为原子转移自由基(ATRP)聚合的天分子引发剂,在60℃引发甲基丙烯酸-N,N-二甲氨基乙酯(DMAEMA)聚合,再将PDMAEMA接枝到纤维素上.以此作为模板,在其水溶液中搅拌加入前驱体正硅酸乙酯(TEOS),水解产生二氧化硅凝胶并吸附在模板上,形成二氧化硅棒,通过红外光谱(FT-IR),热重分析(TGA)和透射电镜(TEM)对产物的结构、组成进行了表征.研究了pH值、TEOS用量、水解时间对二氧化硅棒形态的影响.实验结果表明,在pH=4,TEOS浓度为10mg/mL时,水解24 h~36 h,可以获得较好的棒状结构.%Cellulose was acylated with 2-bromobutyrylbromide at ambient temperature in ionic liquid (RTIL), 1allyi-3-methylimidazolium chloride, giving polyfunctional macroinitiators for atom transfer radical polymerization (ATRP). Copolymers were obtained via ATRP of N, N-dimethylamino-2-ethyl methacrylate (DMAEMA) with CuBr/pentamethyldiethylenetriamine (PMDETA) as catalyst and N, N-dimethylformamide (DMF) as solvent at 60 ℃. The resultant Cellulose-graft-poly (N, N-dimethylamino-2-ethyl methacrylate) (cellulose-g-PDMAEMA) was dissolved in distilled water under stirring. Mesoporous silica nanotubes were synthesized under mild conditions by applying conventional sol gel routes using tetraethyl orthosilicate (TEOS) as the precursors. The results were confirmed via FT-IR, TGA and TEM. The effect of the pH value, the concentration of TEOS and polycondensation time on the morphology of silicarod was studied. The results show that the desirable morphology of silicarod can be obtained from polycondensation of TEOS in aqueous solution with concentration of 10 mg/mL at pH= 4 for 24 h~36 h.

  16. Defining biocultural approaches to conservation.

    Science.gov (United States)

    Gavin, Michael C; McCarter, Joe; Mead, Aroha; Berkes, Fikret; Stepp, John Richard; Peterson, Debora; Tang, Ruifei

    2015-03-01

    We contend that biocultural approaches to conservation can achieve effective and just conservation outcomes while addressing erosion of both cultural and biological diversity. Here, we propose a set of guidelines for the adoption of biocultural approaches to conservation. First, we draw lessons from work on biocultural diversity and heritage, social-ecological systems theory, integrated conservation and development, co-management, and community-based conservation to define biocultural approaches to conservation. Second, we describe eight principles that characterize such approaches. Third, we discuss reasons for adopting biocultural approaches and challenges. If used well, biocultural approaches to conservation can be a powerful tool for reducing the global loss of both biological and cultural diversity.

  17. Ablative Approaches for Pulmonary Metastases.

    Science.gov (United States)

    Boyer, Matthew J; Ricardi, Umberto; Ball, David; Salama, Joseph K

    2016-02-01

    Pulmonary metastases are common in patients with cancer for which surgery is considered a standard approach in appropriately selected patients. A number of patients are not candidates for surgery due to a medical comorbidities or the extent of surgery required. For these patients, noninvasive or minimally invasive approaches to ablate pulmonary metastases are potential treatment strategies. This article summarizes the rationale and outcomes for non-surgical treatment approaches, including radiotherapy, radiofrequency and microwave ablation, for pulmonary metastases.

  18. Amplitude dependent closest tune approach

    CERN Document Server

    Tomas Garcia, Rogelio; Franchi, Andrea; Maclean, Ewen Hamish; CERN. Geneva. ATS Department

    2016-01-01

    Recent observations in the LHC point to the existence of an amplitude dependent closest tune approach. However this dynamical behavior and its underlying mechanism remain unknown. This effect is highly relevant for the LHC as an unexpectedly closest tune approach varying with amplitude modifies the frequency content of the beam and, hence, the Landau damping. Furthermore the single particle stability would also be affected by this effect as it would modify how particles with varying amplitudes approach and cross resonances. We present analytic derivations that lead to a mechanism generating an amplitude dependent closest tune approach.

  19. Managerial Approach to Public Administration

    Directory of Open Access Journals (Sweden)

    Cristina Maria MORA

    2008-10-01

    Full Text Available The paper discusses the issue of themanagerial approach to public administration,starting from the distinction identified by someauthors between management and administration.The paper has a twofold structure: in the firstsections it provides a theoretical conceptualframework for approaching the issue of themanagerial approach to public administration;in the following sections, the authors discuss themanagerial approach with regard to the Romanianadministrative sector. In the conclusion section,the paper tries to offer an answer to the questionwhere do we stand as a country with regard tothe implementation of the managerial approachin public administration. While some progress hasbeen made, there are nonetheless steps that stillneed to be taken..

  20. New Approaches to Final Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Neuffer, David [Fermilab

    2014-11-10

    A high-energy muon collider scenario require a “final cooling” system that reduces transverse emittances by a factor of ~10 while allowing longitudinal emittance increase. The baseline approach has low-energy transverse cooling within high-field solenoids, with strong longitudinal heating. This approach and its recent simulation are discussed. Alternative approaches which more explicitly include emittance exchange are also presented. Round-to-flat beam transform, transverse slicing, and longitudinal bunch coalescence are possible components of the alternative approach. A more explicit understanding of solenoidal cooling beam dynamics is introduced.

  1. Recent approaches to immune networks

    NARCIS (Netherlands)

    Boer, R.J. de; Neumann, A.U.; Perelson, A.S.; Segel, L.A.; Weisbuch, G.W.

    1993-01-01

    Jerne (1974) proposed that the immune system has important network characteristics that are similar in many respects to neural networks. This paper outlines some recent approaches taken by the authors and their colleagues toward the analysis of immune networks. Other approaches have been omitted owi

  2. ADOPT COMMUNICATIVE APPROACHES IN CET

    Institute of Scientific and Technical Information of China (English)

    LinSitan

    2004-01-01

    How to make CET tailored to the requirements of thesociety is a topic of great significance. This paper is meant toexplore the advantages of adopting communicative approaches inCET( College English Teaching ) by comparing communicativeapproaches with traditional ones and presenting our practice ofemploying communicative approaches as well as the result.

  3. Geometry: A Flow Proof Approach.

    Science.gov (United States)

    McMurray, Robert

    The inspiration for this text was provided by an exposure to the flow proof approach to a proof format as opposed to the conventional two-column approach. Historical background is included, to provide a frame of reference to give the student an appreciation of the subject. The basic constructions are introduced early and briefly, to aid the…

  4. [Endoscopic approaches to the orbit].

    Science.gov (United States)

    Cebula, H; Lahlou, A; De Battista, J C; Debry, C; Froelich, S

    2010-01-01

    During the last decade, the use of endoscopic endonasal approaches to the pituitary has increased considerably. The endoscopic endonasal and transantral approaches offer a minimally invasive alternative to the classic transcranial or transconjunctival approaches to the medial aspect of the orbit. The medial wall of the orbit, the orbital apex, and the optic canal can be exposed through a middle meatal antrostomy, an anterior and posterior ethmoidectomy, and a sphenoidotomy. The inferomedial wall of the orbit can be also perfectly visualized through a sublabial antrostomy or an inferior meatal antrostomy. Several reports have described the use of an endoscopic approach for the resection or the biopsy of lesions located on the medial extraconal aspect of the orbit and orbital apex. However, the resection of intraconal lesions is still limited by inadequate instrumentation. Other indications for the endoscopic approach to the orbit are the decompression of the orbit for Graves' ophthalmopathy and traumatic optic neuropathy. However, the optimal management of traumatic optic neuropathy remains very controversial. Endoscopic endonasal decompression of the optic nerve in case of tumor compression could be a more valid indication in combination with radiation therapy. Finally, the endoscopic transantral treatment of blowout fracture of the floor of the orbit is an interesting option that avoids the eyelid or conjunctive incision of traditional approaches. The collaboration between the neurosurgeon and the ENT surgeon is mandatory and reduces the morbidity of the approach. Progress in instrumentation and optical devices will certainly make this approach promising for intraconal tumor of the orbit.

  5. A Critique of Interactional Approach

    Institute of Scientific and Technical Information of China (English)

    Bao Fang

    2011-01-01

    Interactional approach is a very important theory in second language acquisition, including the input hypothesis and interaction hypothesis. This article first presents an exposition of these two hypotheses, and continues with a critical evaluation of them. Finally, the article concludes with the pedagogical implications of the approach.

  6. Mitochondrial biogenesis: pharmacological approaches.

    Science.gov (United States)

    Valero, Teresa

    2014-01-01

    Organelle biogenesis is concomitant to organelle inheritance during cell division. It is necessary that organelles double their size and divide to give rise to two identical daughter cells. Mitochondrial biogenesis occurs by growth and division of pre-existing organelles and is temporally coordinated with cell cycle events [1]. However, mitochondrial biogenesis is not only produced in association with cell division. It can be produced in response to an oxidative stimulus, to an increase in the energy requirements of the cells, to exercise training, to electrical stimulation, to hormones, during development, in certain mitochondrial diseases, etc. [2]. Mitochondrial biogenesis is therefore defined as the process via which cells increase their individual mitochondrial mass [3]. Recent discoveries have raised attention to mitochondrial biogenesis as a potential target to treat diseases which up to date do not have an efficient cure. Mitochondria, as the major ROS producer and the major antioxidant producer exert a crucial role within the cell mediating processes such as apoptosis, detoxification, Ca2+ buffering, etc. This pivotal role makes mitochondria a potential target to treat a great variety of diseases. Mitochondrial biogenesis can be pharmacologically manipulated. This issue tries to cover a number of approaches to treat several diseases through triggering mitochondrial biogenesis. It contains recent discoveries in this novel field, focusing on advanced mitochondrial therapies to chronic and degenerative diseases, mitochondrial diseases, lifespan extension, mitohormesis, intracellular signaling, new pharmacological targets and natural therapies. It contributes to the field by covering and gathering the scarcely reported pharmacological approaches in the novel and promising field of mitochondrial biogenesis. There are several diseases that have a mitochondrial origin such as chronic progressive external ophthalmoplegia (CPEO) and the Kearns- Sayre syndrome (KSS

  7. SYNTHESIS AND CHARACTERIZATION OF STAR-SHAPED POLY ( ε-CAPROLACTONE ) -b-POLY ( 2-HYDROXYETHYL METHACRYLATE) BLOCK COPOLYMER%星型两亲性聚己内酯-b-聚甲基丙烯酸(2-羟乙酯)嵌段共聚物的合成和表征

    Institute of Scientific and Technical Information of China (English)

    王蓓蕾; 涂松; 邱永兵; 陈元维; 罗祥林

    2011-01-01

    通过开环聚合(ROP)和原子转移自由基聚合(ATRP)制备了一类新型的两亲性嵌段共聚物——六臂星形聚(ε-已内酯)-b-聚甲基丙烯酸(2-羟乙酯)(6sPCL-b-PHEMA).6sPCL-b-PHEMA通过三步反应合成:(1)双季戊四醇开环聚合ε-己内酯的合成6sPCL;(2)以2-溴异丁基酰溴封端星形聚合物制备大分子引发剂6sPCL-Br;(3)采用溴化亚铜[Cu(I) Br]和2,2'-联吡啶(Bpy)催化甲基丙烯酸(2-羟乙酯)(HEMA)单体聚合合成具有不同亲疏水链段比的6sPCL-b-PHEMA.通过核磁氢谱(1H-NMR)和红外光谱(FT-IR)对共聚物的化学结构进行表征,确认合成了目标产物.利用示差扫描量热仪(DSC)对其热性能并利用接触角测量仪对材料的膜的亲水性进行了研究,结果表明,PCL与HEMA进行共聚以后,可以降低PCL的结晶性并提高聚合物的亲水性,随着HEMA在共聚物中含量的增加,这种趋势更加明显.%The six-arm star-shaped amphiphilic block copolymers poly ( ε-caprolactone ) -b-poly ( 2-hydroxyethyl methacrylate ) ( 6sPCL-b-PHEMA ) were prepared by a combination of ring-opening polymerization ( ROP) and atom transfer radical polymerization ( ATRP). The synthesis procedure was composed of three step reactions;First,6sPCL homopolymers were prepared via ring-opening polymerization of ^-caprolactone by using dipentaerythritol with 6 hydroxyl functional groups as an initiator; Second,6sPCL was functionalized to get macroinitiator 6sPCL-Br for ATRP; Third, atom transfer radical polymerization of 2-hydroxyethyl methacrylate (HEMA) from the macroinitiator 6sPCL-Br was conducted by using copper ( I ) bromide ( Cu(I)Br) and 2,2'-bipyredine (Bpy) as catalyze system to synthesize the star block copolymer 6sPCL-6-PHEMA. Molecular structure of 6sPCL-6-PHEMA was confirmed by1 H nuclear magnetic resonance (1H-NMR) and Fourier transform infrared ( FTIR) spectroscopy. Thermal behavior and hydrophilicity of obtained 6sPCL-6-PHEMA were measured by DSC and water contact

  8. Integrating Communicative Approaches with Traditional Approaches in ELT

    Institute of Scientific and Technical Information of China (English)

    陈超

    2013-01-01

    Traditional y, English teaching in China is dominated by a teacher-centered, grammar-translation and audio-lingual method and an emphasis on rote learning. In an attempt to find out what are the most appropriate teaching methods for Chinese students in schools, the paper presents that the best method is to integrate communicative approaches to the teaching of English with traditional Chinese methods. It shows that integrating communicative approaches with the traditional approaches can real y help the students develop their communicative competence.

  9. Surgical Approaches to Breast Augmentation: The Transaxillary Approach.

    Science.gov (United States)

    Strock, Louis L

    2015-10-01

    The transaxillary approach to breast augmentation has the advantage of allowing breast implants to be placed with no incisions on the breasts. There has been a general perception of a lack of technical control compared with the inframammary approach. This article presents the transaxillary approach from the perspective of the technical control gained with the aid of an endoscope, which allows precise creation of the tissue pocket with optimal visualization. The aspects of technique that allow optimal technical control are discussed, in addition to postoperative processes that aid in stabilizing the device position and allow consistent and predictable outcomes.

  10. Lexical Approach to English Teaching

    Institute of Scientific and Technical Information of China (English)

    刘朝彦

    2001-01-01

    @@ 0. Introduction Advances in computer analysis of the English language have shown that lexical patterns are widespread in language use. Some researchers call them "lexical phrases" (Nattinger and DeCarrico,1992) or "lexical chunks" (Lewis, 1993); others use the term "multi-word chunks" or just "chunks"of language. Whatever the terms are, they are characteristic of language use and language acquisition and present advantages for language teaching and learning. The lexical approach to English teaching has received interest in recent years as an alternative to grammar-based approaches. The lexical approach concentrates on developing learners' skills in understanding and using words and word combinations.

  11. Approaches to Scandinavian Crime Fiction

    DEFF Research Database (Denmark)

    Agger, Gunhild

    2010-01-01

    The working paper discusses some of the major approaches to Scandinavian crime fiction in the light of the dominant features of crime culture, e.g. the broad exposure of crime fiction via different platforms and media. In this connection, the concept of mediatization is considered as well...... as the approach of genre typology and the concept of evil – seemingly disparate concepts and approaches, but all related to the complex processes in the borderlands between crime fiction and society. Using examples from Scandinavian crime fiction, I discuss whether the growing proximity to international genres......, ways of production and standards increasingly removes Scandinavian crime fiction from its original attractions or not....

  12. THE APPROACHING TRAIN DETECTION ALGORITHM

    Directory of Open Access Journals (Sweden)

    S. V. Bibikov

    2015-09-01

    Full Text Available The paper deals with detection algorithm for rail vibroacoustic waves caused by approaching train on the background of increased noise. The urgency of algorithm development for train detection in view of increased rail noise, when railway lines are close to roads or road intersections is justified. The algorithm is based on the method of weak signals detection in a noisy environment. The information statistics ultimate expression is adjusted. We present the results of algorithm research and testing of the train approach alarm device that implements the proposed algorithm. The algorithm is prepared for upgrading the train approach alarm device “Signalizator-P".

  13. Vanpooling: the three major approaches

    Energy Technology Data Exchange (ETDEWEB)

    Sears, P.M.

    1979-08-01

    The manual provides technical assistance to existing or prospective vanpool sponsors. It is designed to help them promote vanpooling in its three major approaches: employer sponsored, third party sponsored, and driver owned and operated. The first chapter is an overview of vanpooling and a second chapter, on vanpool marketing, is addressed to ridesharing coordinators and others whose responsibilities include the promotion of vanpooling. Some fact sheets on the three approaches provide convenient summaries of the needs and opportunities of each approach and suggest solutions to practical problems likely to be encountered in starting new vanpool programs.

  14. A Biosemiotic Approach to Health

    DEFF Research Database (Denmark)

    Hoffmeyer, Jesper

    2010-01-01

    approaches are invaluable. The aim is to find a common platform that serves in treating human persons as undivided wholes. Since semiosis (viz. the meaningful interpretation of cues, signals, events or states) is vital to communication at both levels, the resulting sign-process is a viable choice......By replacing the traditional chemical approach to the understanding of body function by a sign-theoretic or semiotic approach, biosemiotics enters a no-man’s-land between biological and social domains of human life. The aim is not to subsume the social under the biological or vice versa; both...

  15. Theoretical approaches to elections defining

    Directory of Open Access Journals (Sweden)

    Natalya V. Lebedeva

    2011-01-01

    Full Text Available Theoretical approaches to elections defining develop the nature, essence and content of elections, help to determine their place and a role as one of the major national law institutions in democratic system.

  16. Approaches to Teaching Organizational Communication.

    Science.gov (United States)

    Applebaum, Ronald L.

    1998-01-01

    Discusses fundamental problems in selecting an approach to organizational communications; the purpose of an organizational communication course; the structure and content of organizational communication coursework; and teaching strategies used in the basic course in organizational communication. (RS)

  17. An Approach to Interface Synthesis

    DEFF Research Database (Denmark)

    Madsen, Jan; Hald, Bjarne

    1995-01-01

    may contain the re-use of existing modules). The interface synthesis approach describes the basic transformations needed to transform the server interface description into an interface description on the client side of the communication medium. The synthesis approach is illustrated through a point......Presents a novel interface synthesis approach based on a one-sided interface description. Whereas most other approaches consider interface synthesis as optimizing a channel to existing client/server modules, we consider the interface synthesis as part of the client/server module synthesis (which......-to-point communication, but is applicable to synthesis of a multiple client/server environment. The interface description is based on a formalization of communication events....

  18. Classical approach in quantum physics

    CERN Document Server

    Solov'ev, Evgeni A

    2010-01-01

    The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom recently discovered with the help of Poincar$\\acute{\\mathrm{e}}$ section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treating as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semicla...

  19. Radiological Approach to Forefoot Pain

    Directory of Open Access Journals (Sweden)

    Sai Chung Ho

    2015-06-01

    Full Text Available Forefoot pain is a common clinical complaint in orthopaedic practice. In this article, we discuss the anatomy of the forefoot, clinical and radiological approaches to forefoot pain, and common painful forefoot disorders and their associated radiological features.

  20. Team Approach to Pain Relief

    Science.gov (United States)

    ... Navigation Bar Home Current Issue Past Issues The Team Approach to Pain Relief Past Issues / Fall 2007 ... Roberts is seen here with some of the team members, (left to right) Dr. Berger, Jacques Bolle, ...

  1. Necrotizing fasciitis: an alternative approach

    OpenAIRE

    Percival, R.; Hargreaves, A. W.

    1982-01-01

    Three cases of necrotizing fasciitis are presented. The initial management of necrotizing fasciitis remains undisputed. However, following a limited success with a conventional treatment policy, a more radical approach with immediate skin grafting following debridement is suggested.

  2. Abstract Cauchy problems three approaches

    CERN Document Server

    Melnikova, Irina V

    2001-01-01

    Although the theory of well-posed Cauchy problems is reasonably understood, ill-posed problems-involved in a numerous mathematical models in physics, engineering, and finance- can be approached in a variety of ways. Historically, there have been three major strategies for dealing with such problems: semigroup, abstract distribution, and regularization methods. Semigroup and distribution methods restore well-posedness, in a modern weak sense. Regularization methods provide approximate solutions to ill-posed problems. Although these approaches were extensively developed over the last decades by many researchers, nowhere could one find a comprehensive treatment of all three approaches.Abstract Cauchy Problems: Three Approaches provides an innovative, self-contained account of these methods and, furthermore, demonstrates and studies some of the profound connections between them. The authors discuss the application of different methods not only to the Cauchy problem that is not well-posed in the classical sense, b...

  3. A Mathematical Approach to Hybridization

    Science.gov (United States)

    Matthews, P. S. C.; Thompson, J. J.

    1975-01-01

    Presents an approach to hybridization which exploits the similarities between the algebra of wave functions and vectors. This method will account satisfactorily for the number of orbitals formed when applied to hybrids involving the s and p orbitals. (GS)

  4. Potential alternative approaches to xenotransplantation.

    Science.gov (United States)

    Mou, Lisha; Chen, Fengjiao; Dai, Yifan; Cai, Zhiming; Cooper, David K C

    2015-11-01

    There is an increasing worldwide shortage of organs and cells for transplantation in patients with end-stage organ failure or cellular dysfunction. This shortage could be resolved by the transplantation of organs or cells from pigs into humans. What competing approaches might provide support for the patient with end-stage organ or cell failure? Four main approaches are receiving increasing attention - (i) implantable mechanical devices, although these are currently limited almost entirely to devices aimed at supporting or replacing the heart, (ii) stem cell technology, at present directed mainly to replace absent or failing cells, but which is also fundamental to progress in (iii) tissue engineering and regenerative medicine, in which the ultimate aim is to replace an entire organ. A final novel potential approach is (iv) blastocyst complementation. These potential alternative approaches are briefly reviewed, and comments added on their current status and whether they are now (or will soon become) realistic alternative therapies to xenotransplantation.

  5. Simplified Approach to Inspection Planning

    DEFF Research Database (Denmark)

    Bloch, Allan; Sørensen, John Dalsgaard; Faber, M. H.

    2000-01-01

    A simplified and practically applicable approach for risk based inspection planning of fatigue sensitive structural details is presented. The basic idea behind the approach is that the fatigue sensitive details are categorized according to their stress intensity factors and their design fatigue l...... of steel structures. The validity of the proposed approach is illustrated through a study regarding inspection planning of offshore structures....... life to service life ratio, i.e. the fatigue design factor (FDF) and SN curve. When the reserve strength ratio (RSR) and the corresponding probability of total structural failure given fatigue failure of the considered detail is known it is possible to make a generic description of fatigue sensitive...... structural details and thereby develop pre-made inspection plans in tables which depend on relative cost of inspections, repairs and failures. Due to the simplicity of the format of the developed inspection plans the proposed approach has a high potential in code making for the design and maintenance...

  6. Nonlinear Approaches in Engineering Applications

    CERN Document Server

    Jazar, Reza

    2012-01-01

    Nonlinear Approaches in Engineering Applications focuses on nonlinear phenomena that are common in the engineering field. The nonlinear approaches described in this book provide a sound theoretical base and practical tools to design and analyze engineering systems with high efficiency and accuracy and with less energy and downtime. Presented here are nonlinear approaches in areas such as dynamic systems, optimal control and approaches in nonlinear dynamics and acoustics. Coverage encompasses a wide range of applications and fields including mathematical modeling and nonlinear behavior as applied to microresonators, nanotechnologies, nonlinear behavior in soil erosion,nonlinear population dynamics, and optimization in reducing vibration and noise as well as vibration in triple-walled carbon nanotubes. This book also: Provides a complete introduction to nonlinear behavior of systems and the advantages of nonlinearity as a tool for solving engineering problems Includes applications and examples drawn from the el...

  7. Approaches for assessing sustainable remediation

    DEFF Research Database (Denmark)

    Søndergaard, Gitte Lemming; Binning, Philip John; Bjerg, Poul Løgstrup

    Sustainable remediation seeks to reduce direct contaminant point source impacts on the environment, while minimizing the indirect cost of remediation to the environment, society and economy. This paper presents an overview of available approaches for assessing the sustainability of alternative...... remediation strategies for a contaminated site. Most approaches use multi-criteria assessment methods (MCA) to structure a decision support process. Different combinations of environmental, social and economic criteria are employed, and are assessed either in qualitative or quantitative forms with various...... tools such as life cycle assessment and cost benefit analysis. Stakeholder involvement, which is a key component of sustainable remediation, is conducted in various ways. Some approaches involve stakeholders directly in the evaluation or weighting of criteria, whereas other approaches only indirectly...

  8. The Database State Machine Approach

    OpenAIRE

    1999-01-01

    Database replication protocols have historically been built on top of distributed database systems, and have consequently been designed and implemented using distributed transactional mechanisms, such as atomic commitment. We present the Database State Machine approach, a new way to deal with database replication in a cluster of servers. This approach relies on a powerful atomic broadcast primitive to propagate transactions between database servers, and alleviates the need for atomic comm...

  9. Deformation analysis: The Fredericton approach

    OpenAIRE

    Vrečko, Anja; Ambrožič, Tomaž

    2013-01-01

    In this article, the Fredericton approach to deformation analysis is presented. It is possible to use several deformation models to determine the differences between the geodetic observations or between the coordinates of points in geodetic network in more epochs. The most appropriate deformation model has been chosen based on statistical testing and available information about dynamics at the area of interest. First, a theoretical background of the approach ...

  10. Bounding approaches to system identification

    CERN Document Server

    Norton, John; Piet-Lahanier, Hélène; Walter, Éric

    1996-01-01

    In response to the growing interest in bounding error approaches, the editors of this volume offer the first collection of papers to describe advances in techniques and applications of bounding of the parameters, or state variables, of uncertain dynamical systems. Contributors explore the application of the bounding approach as an alternative to the probabilistic analysis of such systems, relating its importance to robust control-system design.

  11. Anteromedial Approach to the Orbit

    OpenAIRE

    DEDA, Haluk; Ugur, Hasan Çaglar; Yorulmaz, Irfan; Kucuk, Babur

    2001-01-01

    This study evaluated the surgical results of the anteromedial approach for treatment of orbital lesions in 16 patients. Pre- and postoperatively, all patients underwent a complete physical examination focusing on the head and neck area including a thorough ophthalmologic evaluation, computerized tomography, and magnetic resonance imaging. The surgical approach was limited to a medial orbitotomy in five patients; the remaining 11 patients underwent a medial orbitotomy combined with an external...

  12. Approaches toward learning in physiotherapy

    Directory of Open Access Journals (Sweden)

    L. Keiller

    2013-01-01

    Full Text Available The aim of this study was to investigate the approaches toward learning of undergraduate Physiotherapy students in a PBl module to enhance facilitation of learning at the Stellenbosch University, Division of Physiotherapy in South Africa. This quantitative, descriptive study utilized the revised Two-factor Study Process Questionnaire (r-SPQ-2f to evaluate the study cohorts’ approaches toward learning in the module. results of the data instruments were analysed statistically and discussed in a descriptive manner. There were a statistically significant greater number of students who adopted a deep approach toward learning at the commencement of the academic year. Students showed a trend toward an increase in their intrinsic interest in the learning material as the module progressed. Students in the Applied Physiotherapy module (ATP started to shift their focus from a surface learning approach to a deep learning approach. further research is needed to determine the long-term changes in approach toward learning and the possible determinants of these changes. This can be done in conjunction with the implementation of quality assurance mechanisms for learning material and earlier preparation of students for the change in the learning environment.

  13. Approach

    Directory of Open Access Journals (Sweden)

    Guido Pinto Aguirre

    2008-01-01

    Full Text Available El propósito de este documento es investigar y re-estimar los efectos de los patrones de lactancia, salud y estado nutricional de la mujer y consumo de energía sobre la duración del retorno de la fertilidad de postparto (es decir, retorno de la menstruación de postparto utilizando toda la información relevante en el estudio longitudinal del Instituto de Nutrición de Centroamérica y Panamá y un procedimiento de estimación más adecuado (modelos de riesgo. Los datos utilizados provienen del Estudio Longitudinal llevado a cabo en Guatemala entre 1967 y 1979. En este artículo se utiliza un modelo de riesgo con varios estados que reconoce diferentes caminos y estados en el proceso del retorno de la fertilidad de postparto. El modelo descansa en la existencia de cinco estados (lactancia total, lactancia parcial, destete, mortalidad infantil y menstruación. También incluye de manera explícita nutrición maternal y consumo de energía de la mujer como elementos estratégicos del modelo. El estudio encontró que los efectos de los patrones de lactancia, nutrición de la madre y patrones de trabajo de la mujer (consumo de energía sobre la fertilidad en las áreas rurales de Guatemala son fuertes y significativos. La contribución de este artículo es mostrar que la aplicación de los modelos de riesgo con múltiples estados proporciona estimados que son consistentes con hipótesis que relacionan patrones de lactancia, estado nutricional maternal y estresores maternales externos a procesos que aceleran (desaceleran el retorno de ciclos menstruales normales.

  14. approach

    Directory of Open Access Journals (Sweden)

    D. J. Rodabaugh

    1978-01-01

    Full Text Available In this paper, the results of the first detailed and systematic study of the family of fifth order implicit linear multistep methods requiring function evaluations at four backpoints are given. Also described is a practical and efficient nonlinear optimization procedure which made it possible to locate in a precise manner the methods of this type which possess optimal ranges of relative stability in the sense-that the corresponding relative stability regions contain maximal disks centered at the origin.

  15. Bayesian Approach for Inconsistent Information.

    Science.gov (United States)

    Stein, M; Beer, M; Kreinovich, V

    2013-10-01

    In engineering situations, we usually have a large amount of prior knowledge that needs to be taken into account when processing data. Traditionally, the Bayesian approach is used to process data in the presence of prior knowledge. Sometimes, when we apply the traditional Bayesian techniques to engineering data, we get inconsistencies between the data and prior knowledge. These inconsistencies are usually caused by the fact that in the traditional approach, we assume that we know the exact sample values, that the prior distribution is exactly known, etc. In reality, the data is imprecise due to measurement errors, the prior knowledge is only approximately known, etc. So, a natural way to deal with the seemingly inconsistent information is to take this imprecision into account in the Bayesian approach - e.g., by using fuzzy techniques. In this paper, we describe several possible scenarios for fuzzifying the Bayesian approach. Particular attention is paid to the interaction between the estimated imprecise parameters. In this paper, to implement the corresponding fuzzy versions of the Bayesian formulas, we use straightforward computations of the related expression - which makes our computations reasonably time-consuming. Computations in the traditional (non-fuzzy) Bayesian approach are much faster - because they use algorithmically efficient reformulations of the Bayesian formulas. We expect that similar reformulations of the fuzzy Bayesian formulas will also drastically decrease the computation time and thus, enhance the practical use of the proposed methods.

  16. Solid mechanics a variational approach

    CERN Document Server

    Dym, Clive L

    2013-01-01

    Solid Mechanics: A Variational Approach, Augmented Edition presents a lucid and thoroughly developed approach to solid mechanics for students engaged in the study of elastic structures not seen in other texts currently on the market. This work offers a clear and carefully prepared exposition of variational techniques as they are applied to solid mechanics. Unlike other books in this field, Dym and Shames treat all the necessary theory needed for the study of solid mechanics and include extensive applications. Of particular note is the variational approach used in developing consistent structural theories and in obtaining exact and approximate solutions for many problems.  Based on both semester and year-long courses taught to undergraduate seniors and graduate students, this text is geared for programs in aeronautical, civil, and mechanical engineering, and in engineering science. The authors’ objective is two-fold: first, to introduce the student to the theory of structures (one- and two-dimensional) as ...

  17. Understanding SARS with Wolfram Approach

    Institute of Scientific and Technical Information of China (English)

    Da-WeiLI; Yu-XiPAN; YunDUAN; Zhen-DeHUNG; Ming-QingXU; LinHE

    2004-01-01

    Stepping acquired immunodeficiency syndrome (AIDS), severe acute respiratory syndrome (SARS) as another type of disease has been threatening mankind since late last year. Many scientists worldwide are making great efforts to study the etiology of this disease with different approaches. 13 species of SARS virus have been sequenced. However, most people still largely rely on the traditional methods with some disadvantages. In this work, we used Wolfram approach to study the relationship among SARS viruses and between SARS viruses and other types of viruses, the effect of variations on the whole genome and the advantages in the analysis of SARS based on this novel approach. As a result, the similarities between SARS viruses and other coronaviruses are not really higher than those between SARS viruses and non-coronaviruses.

  18. Variational Approach to Molecular Kinetics.

    Science.gov (United States)

    Nüske, Feliks; Keller, Bettina G; Pérez-Hernández, Guillermo; Mey, Antonia S J S; Noé, Frank

    2014-04-08

    The eigenvalues and eigenvectors of the molecular dynamics propagator (or transfer operator) contain the essential information about the molecular thermodynamics and kinetics. This includes the stationary distribution, the metastable states, and state-to-state transition rates. Here, we present a variational approach for computing these dominant eigenvalues and eigenvectors. This approach is analogous to the variational approach used for computing stationary states in quantum mechanics. A corresponding method of linear variation is formulated. It is shown that the matrices needed for the linear variation method are correlation matrices that can be estimated from simple MD simulations for a given basis set. The method proposed here is thus to first define a basis set able to capture the relevant conformational transitions, then compute the respective correlation matrices, and then to compute their dominant eigenvalues and eigenvectors, thus obtaining the key ingredients of the slow kinetics.

  19. A general approach to bosonization

    Indian Academy of Sciences (India)

    Girish S Setulur; V Meera

    2007-10-01

    We summarize recent developments in the field of higher dimensional bosonization made by Setlur and collaborators and propose a general formula for the field operator in terms of currents and densities in one dimension using a new ingredient known as a `singular complex number'. Using this formalism, we compute the Green function of the homogeneous electron gas in one spatial dimension with short-range interaction leading to the Luttinger liquid and also with long-range interactions that lead to a Wigner crystal whose momentum distribution computed recently exhibits essential singularities. We generalize the formalism to finite temperature by combining with the author's hydrodynamic approach. The one-particle Green function of this system with essential singularities cannot be easily computed using the traditional approach to bosonization which involves the introduction of momentum cutoffs, hence the more general approach of the present formalism is proposed as a suitable alternative.

  20. City evacuations an interdisciplinary approach

    CERN Document Server

    Binner, Jane; Branicki, Layla; Galla, Tobias; Jones, Nick; King, James; Kolokitha, Magdalini; Smyrnakis, Michalis

    2015-01-01

    Evacuating a city is a complex problem that involves issues of governance, preparedness education, warning, information sharing, population dynamics, resilience and recovery. As natural and anthropogenic threats to cities grow, it is an increasingly pressing problem for policy makers and practitioners.   The book is the result of a unique interdisciplinary collaboration between researchers in the physical and social sciences to consider how an interdisciplinary approach can help plan for large scale evacuations.  It draws on perspectives from physics, mathematics, organisation theory, economics, sociology and education.  Importantly it goes beyond disciplinary boundaries and considers how interdisciplinary methods are necessary to approach a complex problem involving human actors and increasingly complex communications and transportation infrastructures.   Using real world case studies and modelling the book considers new approaches to evacuation dynamics.  It addresses questions of complexity, not only ...

  1. Toward predicate approaches to modality

    CERN Document Server

    Stern, Johannes

    2016-01-01

    In this volume, the author investigates and argues for, a particular answer to the question: What is the right way to logically analyze modalities from natural language within formal languages? The answer is: by formalizing modal expressions in terms of predicates. But, as in the case of truth, the most intuitive modal principles lead to paradox once the modal notions are conceived as predicates. The book discusses the philosophical interpretation of these modal paradoxes and argues that any satisfactory approach to modality will have to face the paradoxes independently of the grammatical category of the modal notion. By systematizing modal principles with respect to their joint consistency and inconsistency, Stern provides an overview of the options and limitations of the predicate approach to modality that may serve as a useful starting point for future work on predicate approaches to modality. Stern also develops a general strategy for constructing philosophically attractive theories of modal notions conce...

  2. The narrative approach in Bioethics

    Directory of Open Access Journals (Sweden)

    Mario Picozzi

    2015-04-01

    Full Text Available Nowadays, the narrative approach in Bioethics is more and more considered and used. In our paper we would like to explain why – when we need to take a decision – it is essential and crucial that the patient tells his own history; we also indicate the main consequences that this approach has with reference to the choices at the bed of the patient. Selected Papers of the Congress “Narrative Based Medicine and Communication in Clinical Practice” · Cagliari, Italy · April 14th, 2014 Guest Editors: Massimiliano Zonza, Vassilios Fanos, Gian Paolo Donzelli

  3. Elementary calculus an infinitesimal approach

    CERN Document Server

    Keisler, H Jerome

    2012-01-01

    This first-year calculus book is centered around the use of infinitesimals, an approach largely neglected until recently for reasons of mathematical rigor. It exposes students to the intuition that originally led to the calculus, simplifying their grasp of the central concepts of derivatives and integrals. The author also teaches the traditional approach, giving students the benefits of both methods.Chapters 1 through 4 employ infinitesimals to quickly develop the basic concepts of derivatives, continuity, and integrals. Chapter 5 introduces the traditional limit concept, using approximation p

  4. Systems biology approach to bioremediation

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Romy; Wu, Cindy H.; Hazen, Terry C.

    2012-06-01

    Bioremediation has historically been approached as a ‘black box’ in terms of our fundamental understanding. Thus it succeeds and fails, seldom without a complete understanding of why. Systems biology is an integrated research approach to study complex biological systems, by investigating interactions and networks at the molecular, cellular, community, and ecosystem level. The knowledge of these interactions within individual components is fundamental to understanding the dynamics of the ecosystem under investigation. Finally, understanding and modeling functional microbial community structure and stress responses in environments at all levels have tremendous implications for our fundamental understanding of hydrobiogeochemical processes and the potential for making bioremediation breakthroughs and illuminating the ‘black box’.

  5. A practical approach to TQI.

    Science.gov (United States)

    Perras, S T; Mattern, M

    1994-04-01

    Total quality improvement (TQI) is a refreshing new approach to leadership that can be applied to a dialysis setting. The team approach to prospective data analysis is used for problem solution and reevaluation. Adapting theory to daily practical application can be successfully done using time, energy, and full senior management commitment. Staff education and involvement are essential to successful program implementation. Evaluation tools are easily adapted to analyze common dialysis problems. The initial time invested in education and data collection can be great but results in a streamlined process.

  6. International Approaches to Clinical Costing

    DEFF Research Database (Denmark)

    Chapman, Christopher; Kern, Anja; Laguecir, Aziza

    This report has been commissioned by both HFMA and Monitor and the work has been led by Imperial College Business School’s Health Management Group. The report compares current approaches to costing, primarily across Europe. The findings reveal wide-ranging practices and uses for costing data......, and provide opportunities for all healthsystems to learn and potentially improve their own approaches. The HFMA hopes to build on this initial baselining exercise to understand more about how key issues are being tackled in some of the health systems that have made the most progress with costing....

  7. Real analysis a constructive approach

    CERN Document Server

    Bridger, Mark

    2012-01-01

    A unique approach to analysis that lets you apply mathematics across a range of subjects This innovative text sets forth a thoroughly rigorous modern account of the theoretical underpinnings of calculus: continuity, differentiability, and convergence. Using a constructive approach, every proof of every result is direct and ultimately computationally verifiable. In particular, existence is never established by showing that the assumption of non-existence leads to a contradiction. The ultimate consequence of this method is that it makes sense-not just to math majors but also to students from a

  8. A Psycho-Societal Approach

    DEFF Research Database (Denmark)

    Mellon, Karsten

    This is a project about Danish vocational bachelor students admitted on the basis of an Individual Competency Assessment (VPL/IKV) in light of a Psycho-Societal Approach. The core idea of this paper is to present a PhD project which aims to contribute findings regarding students enrolled in a Dan......This is a project about Danish vocational bachelor students admitted on the basis of an Individual Competency Assessment (VPL/IKV) in light of a Psycho-Societal Approach. The core idea of this paper is to present a PhD project which aims to contribute findings regarding students enrolled...

  9. Indecisiveness: A Dynamic, Integrative Approach.

    Science.gov (United States)

    Johnson, Douglas Paul

    1990-01-01

    Responds to case of Sondra presented in Career Development Quarterly (September 1990). Suggests that her inability to decide on a career may be rooted in long-term personality style, poor ego strength, noisome family dynamics, and/or developmental delay. Recommends an integrative approach incorporating both personal and career counseling. (PVV)

  10. Writing Approaches of Graduate Students

    Science.gov (United States)

    Lavelle, Ellen; Bushrow, Kathy

    2007-01-01

    The writing approach framework provides a comprehensive perspective on college-level academic writing based on the relationship of writers' beliefs and strategies to the quality of written outcomes. However, despite increased demands for more and better writing at the graduate level, little is known about graduate-level writing processes or about…

  11. Model based feature fusion approach

    NARCIS (Netherlands)

    Schwering, P.B.W.

    2001-01-01

    In recent years different sensor data fusion approaches have been analyzed and evaluated in the field of mine detection. In various studies comparisons have been made between different techniques. Although claims can be made for advantages for using certain techniques, until now there has been no si

  12. Multiaxial diagnosis: An integral approach

    OpenAIRE

    Adalberto Campo Arias

    2003-01-01

    All patients must be diagnosed with an integral, multiaxial or bio-psycho-social model. This approach makes possible understanding biological,personality, social, and cultural factor or background of ill people. Multiaxial perspective gives diagnosis more accurate and reliable. Moreover, it makes clinical practice more warm and humane.

  13. Eight Approaches to Language Teaching.

    Science.gov (United States)

    Doggett, Gina

    Important features of eight second language teaching methods--grammar-translation, direct, audiolingual, the Silent Way, Suggestopedia, community language learning, Total Physical Response, and the communicative approach--are summarized . A chart outlines characteristics of these aspects of the methods: goals, teacher and student roles, the…

  14. Early Writing: A Developmental Approach.

    Science.gov (United States)

    Goetz, Elizabeth; And Others

    This document consists of four papers on the acquisition of writing skills by young children. The first paper provides a historical and developmental perspective on early writing. Children's development of manual dexterity is briefly overviewed and aspects of the educational approaches of Pestalozzi, Montessori, Chomsky, Rogers and Ashton-Warner…

  15. Institutional Planning: A Systems Approach.

    Science.gov (United States)

    Adamson, Willie D.

    This four-chapter report explores the possible contributions of a systems approach to institutional planning. After introductory comments, Chapter I reviews the management theory of Henry Fayol, which emphasizes management tasks, such as planning, organizing, commanding, coordinating, and controlling, which are "universal" regardless of the level…

  16. Force approach to radiation reaction

    Energy Technology Data Exchange (ETDEWEB)

    López, Gustavo V., E-mail: gulopez@udgserv.cencar.udg.mx

    2016-02-15

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  17. Force approach to radiation reaction

    Science.gov (United States)

    López, Gustavo V.

    2016-02-01

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  18. Using Natural Approach Teaching Techniques.

    Science.gov (United States)

    Whitman, Charles

    1986-01-01

    Describes a beginning foreign language class applying the principles of Stephen Krashen's "Natural Approach" and James Asher's "Total Physical Response" method. Initially students carry out the instructor's commands in the form of actions rather than being required to speak. In later stages role play and simple discussions are…

  19. Bilingual Approaches to Language Learning

    Institute of Scientific and Technical Information of China (English)

    MaryMcgroarty; NorthernArizonaUniversity

    2003-01-01

    “Billingual Approaches to Language Learning” describes the various bilingual models found at different levels(elementary,secondary,post-secondary,and adult education),identifying key instructional features and emphasizing the drive for quality instruction.The paper makes reference to consideration of the political contexts as well as pedagogical factors affecting the choices and outcomes related to bilingual instruction.

  20. The Labelling Approach to Deviance.

    Science.gov (United States)

    Rains, Prudence M.; Kitsuse, John L.; Duster, Troy; Freidson, Eliot

    2003-01-01

    This reprint of one chapter from the 1975 text, "Issues in the Classification of Children" by Nicholas Hobbs and others, addresses the theoretical, methodological, and empirical issues involved in the "labeling" approach to the sociology of deviance. It examines the social process of classification, the use of classification in social agencies,…

  1. Approach to the bleeding newborn

    OpenAIRE

    1998-01-01

    Bleeding in the newborn can lead to serious cardiovascular and neurological effects. Routine administration of vitamin K has reduced the incidence of hemorrhagic disease of the newborn, but abnormal bleeding can occur in babies from many causes. A practical approach to the diagnosis and treatment of bleeding in the newborn is described in this article.

  2. Teaching Ethics: A Direct Approach.

    Science.gov (United States)

    Penn, William Y., Jr.

    1990-01-01

    Compares five designs of an undergraduate ethics course at Saint Edward's University (Texas) in a 5-year study involving 318 students. Reveals the effectiveness of directly targeting and teaching in tandem the elements of moral reasoning. Bases study on Lawrence Kohlberg's moral development theory. Argues that this approach best develops moral…

  3. Theoretical Approaches to Political Communication.

    Science.gov (United States)

    Chesebro, James W.

    Political communication appears to be emerging as a theoretical and methodological academic area of research within both speech-communication and political science. Five complimentary approaches to political science (Machiavellian, iconic, ritualistic, confirmational, and dramatistic) may be viewed as a series of variations which emphasize the…

  4. Comparative Psychology: An Epigenetic Approach.

    Science.gov (United States)

    Greenberg, Gary

    1987-01-01

    A comparative psychology course oriented around the themes of phylogeny and ontogeny is described. The course emphasizes the evolution and development of behavioral processes and includes a discussion of the concept of integrative levels and Schneirla's approach/withdrawal theory. The course evaluates genetic determinism and stresses the principle…

  5. Early Intervention Approaches. Chapter 9.

    Science.gov (United States)

    1996

    This collection of papers presented at a 1996 conference on children's mental health focuses on early intervention approaches. Papers have the following titles and authors: (1) "Child Maltreatment and Prenatal Exposure to Alcohol and Other Drugs: Some Preliminary Findings" (Patrick A. Curtis and Mary Wood Schneider); (2) "Evaluation…

  6. A Complexity Approach for Steganalysis

    CERN Document Server

    Bahi, Jacques M; Heam, Pierre-Cyrille

    2011-01-01

    In this proposal for the Journ\\`ees Codes et St\\'eganographie 2012, we define a new rigorous approach for steganalysis based on the complexity theory. It is similar to the definitions of security that can be found for hash functions, PRNG, and so on. We propose here a notion of \\emph{secure hiding} and we give a first secure hiding scheme.

  7. Classical approach in atomic physics

    Science.gov (United States)

    Solov'ev, E. A.

    2011-12-01

    The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of a hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom discovered with the help of Poincaré section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treated as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormgroup symmetry, criterion of accuracy and so on are reviewed as well.

  8. Approaching Bose-Einstein Condensation

    Science.gov (United States)

    Ferrari, Loris

    2011-01-01

    Bose-Einstein condensation (BEC) is discussed at the level of an advanced course of statistical thermodynamics, clarifying some formal and physical aspects that are usually not covered by the standard pedagogical literature. The non-conventional approach adopted starts by showing that the continuum limit, in certain cases, cancels out the crucial…

  9. Geometrical approach to fluid models

    NARCIS (Netherlands)

    Kuvshinov, B. N.; Schep, T. J.

    1997-01-01

    Differential geometry based upon the Cartan calculus of differential forms is applied to investigate invariant properties of equations that describe the motion of continuous media. The main feature of this approach is that physical quantities are treated as geometrical objects. The geometrical notio

  10. Cleft Palate; A Multidiscipline Approach.

    Science.gov (United States)

    Stark, Richard B., Ed.

    Nineteen articles present a multidisciplinary approach to the management of facial clefts. The following subjects are discussed: the history of cleft lip and cleft palate surgery; cogenital defects; classification; the operation of a cleft palate clinic; physical examination of newborns with cleft lip and/or palate; nursing care; anesthesia;…

  11. APPROACH TO SMALL FAMILY NORM

    Directory of Open Access Journals (Sweden)

    Nonibala

    2014-09-01

    Full Text Available The Idea of approach to maintain small family norm in the family and so to the society is the hope for almost all of the couples as the saying -"Small family is a happy family". And every couple always thinks and plan for a safer and better future.

  12. APPROACH TO SMALL FAMILY NORM

    OpenAIRE

    Nonibala

    2014-01-01

    The Idea of approach to maintain small family norm in the family and so to the society is the hope for almost all of the couples as the saying -"Small family is a happy family". And every couple always thinks and plan for a safer and better future.

  13. Classical approach in atomic physics

    Energy Technology Data Exchange (ETDEWEB)

    Solov' ev, E.A. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

    2011-12-15

    The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of a hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom discovered with the help of Poincare section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treated as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormalization group symmetry, criterion of accuracy and so on are reviewed as well. (author)

  14. Dental approach to craniofacial syndromes

    DEFF Research Database (Denmark)

    Kjær, Inger

    2012-01-01

    is essential for insight into craniofacial syndromes. The dentition, thus, becomes central in diagnostics and evaluation of the pathogenesis. Developmental fields can explore and advance the concept of dental approaches to craniofacial syndromes. Discussion. As deviations in teeth persist and do not reorganize...

  15. Three Approaches to Evaluation Research.

    Science.gov (United States)

    Rafter, David O.

    1984-01-01

    Three common evaluation models are the scientific, interactive, and hybrid. A study of evaluation projects mandated by the Wisconsin legislature revealed that the hybrid model was most effective in achieving policy planning and policy control utilization, the interactive approach provided aid to individual utilization, and the scientific approach…

  16. Multidisciplinary Approaches in Evolutionary Linguistics

    Science.gov (United States)

    Gong, Tao; Shuai, Lan; Wu, Yicheng

    2013-01-01

    Studying language evolution has become resurgent in modern scientific research. In this revival field, approaches from a number of disciplines other than linguistics, including (paleo)anthropology and archaeology, animal behaviors, genetics, neuroscience, computer simulation, and psychological experimentation, have been adopted, and a wide scope…

  17. A Freudian Approach to Education.

    Science.gov (United States)

    Gartner, Sandra L.

    This document offers the point of view that Bruno Bettelheim's writings, based on Sigmund Freud's approach to education, suggest the most practical applications for achieving positive results within the classroom. The overall result of a student being taught all through school by the Freudian method would be an extremely positive one. Such a…

  18. A Psychoanalytic Approach to Fieldwork

    Science.gov (United States)

    Ramvi, Ellen

    2012-01-01

    This article focuses on what both psychoanalysis and anthropology have in common: the emphasis on the researcher's own experience. An ethnographic fieldwork will be used to illustrate how a psychoanalytical approach unfolds the material when studying conditions for learning from experience among teachers in two Norwegian junior high schools, and…

  19. Behavioral approach to list decoding

    NARCIS (Netherlands)

    Polderman, Jan Willem; Kuijper, Margreta

    2002-01-01

    List decoding may be translated into a bivariate interpolation problem. The interpolation problem is to find a bivariate polynomial of minimal weighted degree that interpolates a given set of pairs taken from a finite field. We present a behavioral approach to this interpolation problem. With the da

  20. Approaching Environmental Issues in Architecture

    DEFF Research Database (Denmark)

    Petersen, Mads Dines; Knudstrup, Mary-Ann

    2013-01-01

    The research presented here takes its point of departure in the design process with a specific focus on how it is approached when designing energy efficient architecture. This is done through a case-study of a design process in a Danish architectural office. This study shows the importance of hav...

  1. Laparoscopic approach to retrorectal cyst

    Institute of Scientific and Technical Information of China (English)

    Petra Gunkova; Lubomir Martinek; Jan Dostalik; Igor Gunka; Petr Vavra; Miloslav Mazur

    2008-01-01

    Retrorectal cysts are rare benign lesions in the presacral space which are frequently diagnosed in middle-aged females. We report here our experience with two symptomatic female patients who were diagnosed as having a retrorectal cyst and managed using a laparoscopic approach. The two patients were misdiagnosed as having an ovarian cystic lesion after abdominal ultrasonography. Computer tomograghy (CT) scan was mandatory to establish the diagnosis. The trocar port site was the same in both patients. An additional left oophorectomy was done for a coexisting ovarian cystic lesion in one patient in the same setting. There was no postoperative morbidity or mortality and the two patients were discharged on the 5th and 6th post operative days, respectively. Our cases show that laparoscopic management of retrorectal cysts is a safe approach. It reduces surgical trauma and offers an excellent tool for perfect visualization of the deep structures in the presacral space.

  2. NEW APPROACHES TO EXPORT COMPETITIVENESS

    Directory of Open Access Journals (Sweden)

    Alina Petronela NEGREA

    2015-04-01

    Full Text Available The economic literature and the political discourse typically look at international competitiveness mainly by the means of export market shares. However, globalisation, production fragmentation and the growing importance of global value chains (GVCs increasingly challenge traditional approaches of export competitiveness and call for a more accurate and disaggregated level of analysis. Due to the growing fragmentation of production, a country exports now include a significant amount of imports of intermediate goods which are part of the export value. In this case, a simple analysis of the evolution of exports can distort the international competitive position of a country. The article suggests a new approach based on the value-added content of international trade measured by means of global value chain analysis.

  3. Bayesian approach to rough set

    CERN Document Server

    Marwala, Tshilidzi

    2007-01-01

    This paper proposes an approach to training rough set models using Bayesian framework trained using Markov Chain Monte Carlo (MCMC) method. The prior probabilities are constructed from the prior knowledge that good rough set models have fewer rules. Markov Chain Monte Carlo sampling is conducted through sampling in the rough set granule space and Metropolis algorithm is used as an acceptance criteria. The proposed method is tested to estimate the risk of HIV given demographic data. The results obtained shows that the proposed approach is able to achieve an average accuracy of 58% with the accuracy varying up to 66%. In addition the Bayesian rough set give the probabilities of the estimated HIV status as well as the linguistic rules describing how the demographic parameters drive the risk of HIV.

  4. New Approaches to Reliability Assessment

    DEFF Research Database (Denmark)

    Ma, Ke; Wang, Huai; Blaabjerg, Frede

    2016-01-01

    of energy. New approaches for reliability assessment are being taken in the design phase of power electronics systems based on the physics-of-failure in components. In this approach, many new methods, such as multidisciplinary simulation tools, strength testing of components, translation of mission profiles......Power electronics are facing continuous pressure to be cheaper and smaller, have a higher power density, and, in some cases, also operate at higher temperatures. At the same time, power electronics products are expected to have reduced failures because it is essential for reducing the cost......, and statistical analysis, are involved to enable better prediction and design of reliability for products. This article gives an overview of the new design flow in the reliability engineering of power electronics from the system-level point of view and discusses some of the emerging needs for the technology...

  5. Ecosystemic approaches to land degradation

    Energy Technology Data Exchange (ETDEWEB)

    Puigdefabregas, J.; Barrio, G. del; Hill, J.

    2009-07-01

    Land degradation is recognized as the main outcome of desertification. However available procedures for its assessment are still unsatisfactory because are often too costly for surveying large areas and rely on specific components of the degradation process without being able to integrate them in a unique process. One of the objectives of De Survey project is designing and implementing operational procedures for desertification surveillance, including land degradation. A strategic report was compiled and reproduced here for selecting the most appropriate approaches to the project conditions. The report focuses on using attributes of ecosystem maturity as a natural way to integrate the different drivers of land degradation in simple indices. The review surveys different families of attributes concerned with water and energy fluxes through the ecosystem, its capacity to sustain biomass and net primary productivity, and its capacity to structure the space. Finally, some conclusions are presented about the choice criteria of the different approaches in the framne of operational applications. (Author) 20 refs.

  6. Nanorobotics current approaches and techniques

    CERN Document Server

    Ferreira, Antoine

    2013-01-01

    Nanorobot devices now perform a wide variety of tasks at the nanoscale in a wide variety of fields including but not limited to fields such as manufacturing, medicine, supply chain, biology, and outer space. Nanorobotics: Current Approaches and Techniques is a comprehensive overview of this interdisciplinary field with a wide ranging discussion that includes nano-manipulation and industrial nanorobotics, nanorobotics in biology and medicine, nanorobotic sensing, navigation and swarm behavior, and protein and DNA-based nanorobotics. Also included is the latest on topics such as bio-nano-actuators and propulsion and navigation of nanorobotic systems using magnetic fields. Nanorobotics: Current Approaches and Techniques is an ideal book for scientists, researchers, and engineers actively involved in applied and robotic research and development.

  7. Communicative Approach and Educational Success

    Institute of Scientific and Technical Information of China (English)

    Wang Jianfang

    2001-01-01

    The quality and benefit of college English teaching is, to some extent, decided by what methodological approach it employs. The current teaching syllabus adopts the communicative approach, which is well established as the dominant theoretical model in college English teaching. This paper tries to discuss these characteristics and explain why the model, procedure and links of college English teaching in the classroom are so vital to improve the language and communicative abilities of students. The teaching methods cannot and should not be fixed. It is restricted by the English levels and learning strategies of students,and by the academic quality and teaching ideas of teachers. A good teacher is such and flexibly to help his students attain the goal that syllabus demands.

  8. Computational approaches for systems metabolomics.

    Science.gov (United States)

    Krumsiek, Jan; Bartel, Jörg; Theis, Fabian J

    2016-06-01

    Systems genetics is defined as the simultaneous assessment and analysis of multi-omics datasets. In the past few years, metabolomics has been established as a robust tool describing an important functional layer in this approach. The metabolome of a biological system represents an integrated state of genetic and environmental factors and has been referred to as a 'link between genotype and phenotype'. In this review, we summarize recent progresses in statistical analysis methods for metabolomics data in combination with other omics layers. We put a special focus on complex, multivariate statistical approaches as well as pathway-based and network-based analysis methods. Moreover, we outline current challenges and pitfalls of metabolomics-focused multi-omics analyses and discuss future steps for the field.

  9. THE PROCESS APPROACH TO WRITING

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    IntroductionIn China.the method for teaching writing for science students is always regarded as most difficult.Howto teach writing and to comment on or mark students’writing are frequently discussed topics.In thispaper.I will report on what I have done in my writing class.Process ApproachThe‘process approach’to writing is not a new approach:it has been around since the early 1970s.It isalso called a‘multiple drafts process’and consists of generating ideas(pre-writing/input):writing a firstdraft with an emphasis on content(to‘discover’meaning/author’s ideas):writing second and third(andpossibly more)drafts to revise ideas and ways to communicate of these ideas.

  10. An approach to risk assessment

    DEFF Research Database (Denmark)

    Simonsen, L.; Lund, S. P.; Hass, Ulla

    1998-01-01

    indicate that numerous persons are exposed in the working as well as in the general environment to several chemicals, for which almost no data on the effect on subtle neurophysiological functions are available. Development of an approach to risk assessment dealing with this problem is a major challenge...... in the nineties. Different approaches to risk assessment are discussed, the quality of the databases available for hazard assessment are evaluated, and the needs for further research are identified. (C) 1996 Intox Press, Inc.......A strategy for delineating risk factors from use of neurotoxic chemicals was applied to the Danish working environment. An analysis using this strategy disclosed the need for internationally adopted criteria for neurotoxicity, and consequently a working group was established by the Nordic Council...

  11. Direct Approach to Quantum Tunneling

    Science.gov (United States)

    Andreassen, Anders; Farhi, David; Frost, William; Schwartz, Matthew D.

    2016-12-01

    The decay rates of quasistable states in quantum field theories are usually calculated using instanton methods. Standard derivations of these methods rely in a crucial way upon deformations and analytic continuations of the physical potential and on the saddle-point approximation. While the resulting procedure can be checked against other semiclassical approaches in some one-dimensional cases, it is challenging to trace the role of the relevant physical scales, and any intuitive handle on the precision of the approximations involved is at best obscure. In this Letter, we use a physical definition of the tunneling probability to derive a formula for the decay rate in both quantum mechanics and quantum field theory directly from the Minkowski path integral, without reference to unphysical deformations of the potential. There are numerous benefits to this approach, from nonperturbative applications to precision calculations and aesthetic simplicity.

  12. 'Academic literacies approaches to genre'?

    Directory of Open Access Journals (Sweden)

    Brian Street

    Full Text Available I provide an overview of approaches to writing referred to as 'academic literacies' building on broader traditions, such as New Literacy Studies, and I draw out the relevance of such traditions for the ways in which lecturers provide support to their students with regard to the writing requirements of the University. I offer three case studies of the application of academic literacies approaches to programmes concerned with supporting student writing, in the UK and the USA. I briefly conclude by asking how far these accounts and this work can be seen to bring together many of the themes raised at SIGET conferences - including academic literacies and its relation to genre theories - and express the hope that it opens up trajectories for future research and collaboration of the kind they were founded to develop.

  13. Hydraulic Modeling of Lock Approaches

    Science.gov (United States)

    2016-08-01

    cation was that the guidewall design changed from a solid wall to one on pilings in which water was allowed to flow through and/or under the wall ...develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the...magnitudes and directions at lock approaches for open river conditions. The meshes were developed using the Surface- water Modeling System. The two

  14. Review og pattern matching approaches

    DEFF Research Database (Denmark)

    Manfaat, D.; Duffy, Alex; Lee, B. S.

    1996-01-01

    This paper presents a review of pattern matching techniques. The application areas for pattern matching are extensive, ranging from CAD systems to chemical analysis and from manufacturing to image processing. Published techniques and methods are classified and assessed within the context of three...... key issues: pattern classes, similiarity types and mathing methods. It has been shown that the techniques and approaches are as diverse and varied as the applications....

  15. Practical approaches in accident analysis

    Science.gov (United States)

    Stock, M.

    An accident analysis technique based on successive application of structural response, explosion dynamics, gas cloud formation, and plant operation failure mode models is proposed. The method takes into account the nonideal explosion characteristic of a deflagration in the unconfined cloud. The resulting pressure wave differs significantly from a shock wave and the response of structures like lamp posts and walls can differ correspondingly. This gives a more realistic insight into explosion courses than a simple TNT-equivalent approach.

  16. [Diagnostic approach to infectious endocarditis].

    Science.gov (United States)

    Parize, Perrine; Mainardi, Jean-Luc

    2012-04-01

    Major advances in imaging and microbiological procedures have changed the diagnostic approach of infective endocarditis. New imaging tools have improved the search of local complications, systemic embolism and diagnosis of infection of cardiac devices. Moreover, microbiological diagnosis has been transformed by molecular techniques as long as these procedures have highlighted microorganisms thus far neglected by classical techniques. Despite these advances, endocarditis remained a clinical diagnosis which still depends on a high index of clinical suspicion.

  17. Ermakov approach for minisuperspace oscillators

    OpenAIRE

    Rosu, H. C.; Socorro, J.

    1999-01-01

    The WDW equation of arbitrary Hartle-Hawking factor ordering for several minisuperspace universe models, such as the pure gravity FRW and Taub ones, is mapped onto the dynamics of corresponding classical oscillators. The latter ones are studied by the classical Ermakov invariant method, which is a natural aproach in this context. For the more realistic case of a minimally coupled massive scalar field, one can study, within the same type of approach, the corresponding squeezing features as a p...

  18. Sociocultural epidemiology: an essential approach.

    Directory of Open Access Journals (Sweden)

    Paul Hersch-Martínez

    2013-09-01

    Full Text Available The necessity of an inclusive epidemiological approach, capable to attend the diverse dimensions involved in health damage as a reflective phenomenon of society is analyzed. The range of perspectives involved requires an inclusive methodological scope and applicative channels, in order to deal with sanitary realities systematically related to culture and social organization. Some constitutive elements of sociocultural epidemiology are underlined, shaping an operative proposal that can enhance the relationship between disciplines and sectors regarding specific outstanding public health problems.

  19. Study of Chunks Input Approach

    Institute of Scientific and Technical Information of China (English)

    马静

    2003-01-01

    This paper is to describe and investigate Chunks (Lexical Phrases ) Input Approach in vocabulary learning strategies by means of achievement tests,questionnaire surveys and interviews. The study is to reveal how different learners combine different vocabulary learning strategies in their learning process. With the data collected, the author of this paper discusses and summarizes learners' individual differences in selecting vocabulary learning strategies with the hope of giving new insights into English teaching and learning.

  20. A Viable Systems Engineering Approach

    Science.gov (United States)

    2010-04-01

    methodology was not meeting the needs of the sponsors • The Agile approach Scrum was selected as the only viable solution for managing project...Self-organized teams Slide 11 Source: Agile Alliance (http://www.agilealliance.org/) Scrum Applied to Systems Engineering • Scrum is a framework for...ceremonies • A Scrum project is a series of iterations or Sprints where every 2-4 weeks produces fully developed requirements, functional analyses, and

  1. Algebraic Approach to Baryon Structure

    CERN Document Server

    Leviatan, A

    1996-01-01

    We present an algebraic approach to the internal structure of baryons in terms of three constituents. We investigate a collective model in which the nucleon is regarded as a rotating and vibrating oblate top with a prescribed distribution of charges and magnetization. We contrast the collective and single-particle descriptions of baryons and compare the predictions of the model with existing data on masses, electromagnetic elastic and transition form factors and strong decays widths.

  2. Tasting Beijing ,Approaching Olympic Games

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Sponsored by Beijing Tour Administration, co-organized by Singapore Conference and Exhibition Administration Service Co., Ltd. and Beijing Relation Exhibition Co., Ltd., "2007 Beijing International Tour Expo" was held in Beijing in June. Commissioner Du Jiang gave a presentation with the opening ceremmony, and pointed out that with the theme of "Tasting Beijing, Approaching Olympic Games", the expo was a platform of promoting the communication and cooperation between the Chinese and foreign tourism industries.

  3. APPROACHES ON THE COMPETITIVE INTELLIGENCE

    OpenAIRE

    Ioan PETRIŞOR; Natalia Ana STRĂIN (SILAŞ)

    2013-01-01

    Within this study, we approached the concept of "competitive intelligence" (CI), which we consider a key element for the success of a business, especially in the current period, characterized by numerous economic and financial turbulence. According to Society of Competitive Intelligence (SCIP), competitive intelligence is defined as a method of ethical and moral collection, analysis and dissemination of information regarding the competitive environment, opportunities, vulnerabilities, and int...

  4. NEW APPROACHES TO EXPORT COMPETITIVENESS

    OpenAIRE

    Alina Petronela NEGREA

    2015-01-01

    The economic literature and the political discourse typically look at international competitiveness mainly by the means of export market shares. However, globalisation, production fragmentation and the growing importance of global value chains (GVCs) increasingly challenge traditional approaches of export competitiveness and call for a more accurate and disaggregated level of analysis. Due to the growing fragmentation of production, a country exports now include a significant amount of import...

  5. New endoscopic approaches in IBD

    Institute of Scientific and Technical Information of China (English)

    Helmut Neumann; Markus F Neurath; Jonas Mudter

    2011-01-01

    Recent advances in endoscopic imaging techniques have revolutionized the diagnostic approach of patients with inflammatory bowel disease(IBD).New,emerging endoscopic imaging techniques visualized a plethora of new mucosal details even at the cellular and subcellular level.This review offers an overview about new endoscopic techniques,including chromoendoscopy,magnification endoscopy,spectroscopy,confocal laser endomicroscopy and endocytoscopy in the face of IBD.

  6. An efficient iris segmentation approach

    Science.gov (United States)

    Gomai, Abdu; El-Zaart, A.; Mathkour, H.

    2011-10-01

    Iris recognition system became a reliable system for authentication and verification tasks. It consists of five stages: image acquisition, iris segmentation, iris normalization, feature encoding, and feature matching. Iris segmentation stage is one of the most important stages. It plays an essential role to locate the iris efficiently and accurately. In this paper, we present a new approach for iris segmentation using image processing technique. This approach is composed of four main parts. (1) Eliminating reflections of light on the eye image based on inverting the color of the grayscale image, filling holes in the intensity image, and inverting the color of the intensity image to get the original grayscale image without any reflections. (2) Pupil boundary detection based on dividing an eye image to nine sub-images and finding the minimum value of the mean intensity for each sub-image to get a suitable threshold value of pupil. (3) Enhancing the contrast of outer iris boundary using exponential operator to have sharp variation. (4) Outer iris boundary localization based on applying a gray threshold and morphological operations on the rectangular part of an eye image including the pupil and the outer boundaries of iris to find the small radius of outer iris boundary from the center of pupil. The proposed approach has been tested on CASIA v1.0 iris image database and other collected iris image database. The experimental results show that the approach is able to detect pupil and outer iris boundary with high accuracy results approximately 100% and reduce time consuming.

  7. Alternative systematic approaches to training

    Energy Technology Data Exchange (ETDEWEB)

    1995-01-01

    This handbook is approved for use by all DOE Components and contractors. The handbook was prepared primarily for DOE nuclear facilities, but the information can be effectively used by any other type of facility. DOE nuclear, DOE non-nuclear, commercial nuclear reactor, fuel fabrication, chemical processing, or other types of facilities may also apply the principles of this approach and find it useful and applicable to local needs. The handbook provides DOE and contractor operating organizations with concepts and guidance regarding the use of alternative techniques to implement a systematic approach to training (SAT). The techniques described in this handbook are endorsed by DOE and use of the guidance in this handbook is appropriate for establishment of technical training programs at DOE nuclear facilities. The use of guidance on selection and implementation of appropriate training approaches after consideration of job complexity, the consequences of error based on risk/hazard potential, and available training media should result in effective and efficient training programs. The information presented in this handbook can be used to grade the level of effort and formality used in developing training programs.

  8. Proteomic approaches to bacterial differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Norbeck, Angela D.; Callister, Stephen J.; Monroe, Matthew E.; Jaitly, Navdeep; Elias, Dwayne A.; Lipton, Mary S.; Smith, Richard D.

    2006-12-01

    While genomic approaches have been applied for the detection and identification of individual bacteria within microbial communities, analogous proteomics approaches have been effectively precluded due to their inherent complexity. An in silico assessment of peptides that could potentially be present in the proteomes of artificial simple and complex communities was performed to evaluate the effect of proteome complexity on species detection. A mass spectrometry-based proteomics approach was employed to experimentally detect and validate the predicted tryptic peptides initially identified as distinctive within the simple community. An assessment of peptide distinctiveness and the potential for mapping to a particular bacterium within a community was made throughout each step of the study. A second in silico assessment of peptide distinctiveness for a complex community of 25 microorganisms was conducted to investigate the levels of instrumental performance that would be required to experimentally detect these peptides, as well as how performance varied with complexity (e.g., the number of different microorganisms). The experimental data for a simple community showed that it is feasible to predict, observe, and to quantify distinctive peptides from one organism in the presence of at least a 100-fold greater abundance of another, thus yielding putative markers for identifying a bacterium of interest. This work represents a first step towards quantitative proteomic characterization of complex microbial communities and the possible development of community wide markers of perturbations to such communities.

  9. Proteomic approaches to bacterial differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Norbeck, Angela D.; Callister, Stephen J.; Monroe, Matthew E.; Jaitly, Navdeep; Elias, Dwayne A.; Lipton, Mary S.; Smith, Richard D.

    2006-01-02

    While genomic approaches have been applied to the detection and identification of individual bacteria within microbial communities, analogous proteomics approaches have been effectively precluded due to the inherent complexity. An in silico assessment of peptides derived from artificial simple and complex communities was performed to evaluate the effect of proteome complexity on species detection. Detection and validation of predicted peptides initially identified as distinctive within the simple community was experimentally performed using a mass spectrometry-based proteomics approach. An assessment of peptide distinctiveness and the potential for mapping to a particular bacterium within a community was made throughout each step of the study. A second assessment performed in silico of peptide distinctiveness for a complex community of 25 microorganisms was also conducted. The experimental data for a simple community, and the in silico data for a complex community revealed that it is feasible to predict, observe, and quantify distinctive peptides from one organism in the presence of at least a 100-fold greater abundance of another, thus yielding putative markers for the identification of a bacterium of interest. This work represents a first step towards quantitative proteomic characterization of complex microbial communities.

  10. New approaches in GMO detection.

    Science.gov (United States)

    Querci, Maddalena; Van den Bulcke, Marc; Zel, Jana; Van den Eede, Guy; Broll, Hermann

    2010-03-01

    The steady rate of development and diffusion of genetically modified plants and their increasing diversification of characteristics, genes and genetic control elements poses a challenge in analysis of genetically modified organisms (GMOs). It is expected that in the near future the picture will be even more complex. Traditional approaches, mostly based on the sequential detection of one target at a time, or on a limited multiplexing, allowing only a few targets to be analysed at once, no longer meet the testing requirements. Along with new analytical technologies, new approaches for the detection of GMOs authorized for commercial purposes in various countries have been developed that rely on (1) a smart and accurate strategy for target selection, (2) the use of high-throughput systems or platforms for the detection of multiple targets and (3) algorithms that allow the conversion of analytical results into an indication of the presence of individual GMOs potentially present in an unknown sample. This paper reviews the latest progress made in GMO analysis, taking examples from the most recently developed strategies and tools, and addresses some of the critical aspects related to these approaches.

  11. An abstract approach to music.

    Energy Technology Data Exchange (ETDEWEB)

    Kaper, H. G.; Tipei, S.

    1999-04-19

    In this article we have outlined a formal framework for an abstract approach to music and music composition. The model is formulated in terms of objects that have attributes, obey relationships, and are subject to certain well-defined operations. The motivation for this approach uses traditional terms and concepts of music theory, but the approach itself is formal and uses the language of mathematics. The universal object is an audio wave; partials, sounds, and compositions are special objects, which are placed in a hierarchical order based on time scales. The objects have both static and dynamic attributes. When we realize a composition, we assign values to each of its attributes: a (scalar) value to a static attribute, an envelope and a size to a dynamic attribute. A composition is then a trajectory in the space of aural events, and the complex audio wave is its formal representation. Sounds are fibers in the space of aural events, from which the composer weaves the trajectory of a composition. Each sound object in turn is made up of partials, which are the elementary building blocks of any music composition. The partials evolve on the fastest time scale in the hierarchy of partials, sounds, and compositions. The ideas outlined in this article are being implemented in a digital instrument for additive sound synthesis and in software for music composition. A demonstration of some preliminary results has been submitted by the authors for presentation at the conference.

  12. Nonpharmaceutical approaches to pain management.

    Science.gov (United States)

    Corti, Lisa

    2014-03-01

    A nonpharmaceutical approach to managing pain is one that does not employ a medication. The use of such approaches, in conjunction with pharmaceuticals as part of multimodal methods to managing pain, is becoming more popular as evidence is emerging to support their use. Cold therapy, for one, is used to reduce the inflammation and tissue damage seen in acute injuries and can be very effective at reducing acute pain. Incorporating the use of superficial heat therapy when treating pain associated with chronic musculoskeletal conditions is often employed as heat increases blood flow, oxygen delivery, and tissue extensibility. Acupuncture is gaining acceptance in veterinary medicine. Research is confirming that release of endogenous endorphins and enkephalins from the application of needles at specific points around the body can effectively control acute and chronic pain. The use of 2 newer therapies-extracorporeal shockwave therapy and platelet-rich plasma-represent an attempt to eliminate the causes of pain at the tissue level by promoting tissue healing and regeneration. Reviewed in this article, these therapies are intended to be used in conjunction with pharmaceuticals as part of a multimodal approach to pain management.

  13. Computer Algebra, Instrumentation and the Anthropological Approach

    Science.gov (United States)

    Monaghan, John

    2007-01-01

    This article considers research and scholarship on the use of computer algebra in mathematics education following the instrumentation and the anthropological approaches. It outlines what these approaches are, positions them with regard to other approaches, examines tensions between the two approaches and makes suggestions for how work in this…

  14. Fuzzy multiple linear regression: A computational approach

    Science.gov (United States)

    Juang, C. H.; Huang, X. H.; Fleming, J. W.

    1992-01-01

    This paper presents a new computational approach for performing fuzzy regression. In contrast to Bardossy's approach, the new approach, while dealing with fuzzy variables, closely follows the conventional regression technique. In this approach, treatment of fuzzy input is more 'computational' than 'symbolic.' The following sections first outline the formulation of the new approach, then deal with the implementation and computational scheme, and this is followed by examples to illustrate the new procedure.

  15. THE ECLECTIC APPROACH AND ITS USE

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    Introduction The field of ELT is constantly changing, so how shall we deal with the various approaches to ELT in China? To answer this question, I shall firstly define the eclectic approach, then look at reasons for using this approach. Finally, I shall focus on its practical use in senior middle school English teaching. What is the Eclectic Approach? The eclectic approach is a technique which applies varying teaching methods to specific situations.

  16. Commercial dissemination approaches for solar home systems

    Energy Technology Data Exchange (ETDEWEB)

    Terrado, E.

    1997-12-01

    The author discusses the issue of providing solar home systems to primarily rural areas from the perspective of how to commercialize the process. He considers two different approaches, one an open market approach and the other an exclusive market approach. He describes examples of the exclusive market approach which are in process in Argentina and Brazil. Coming from a banking background, the business aspects are discussed in detail. He points out the strengths and weaknesses of both approaches toward developing such systems.

  17. Local approach to quantum entanglement

    Science.gov (United States)

    Ho-Chih, Lin

    Quantum entanglement is the key property that makes quantum information theory different from its classical counterpart and is also a valuable physical resource with massive potential for technological applications. However, our understanding of entanglement is still far from com plete despite intense research activities. Like other physical resources, the first step towards exploiting them fully is to know how to quantify. There are many reasons to focus on the en tanglement of continuous-variable states since the underlying degrees of freedom of physical systems carrying quantum information are frequently continuous, rather than discrete. Much of the effort has been concentrated on Gaussian states, because these are common as the ground or thermal states of optical modes. Within this framework, many interesting topics have been stud ied and some significant progress made. Nevertheless, non-Gaussian states are also extremely important this is especially so in condensed-phase systems, where harmonic behaviour in any degree of freedom is likely to be only an approximation. So far, there is little knowledge about the quantification of entanglement in non-Gaussian states. This thesis aims to contribute to the active field of research in quantum entanglement by introducing a new approach to the analysis of entanglement, especially in continuous-variable states, and shows that it leads to the first systematic quantification of the (local) entanglement in arbitrary bipartite non-Gaussian states. By applying this local approach, many new insights can be gained. Notably, local entanglements of systems with smooth wavefunctions are fully characterised by the derived simple expressions, provided the wavefunction is known. The local (logarithmic) negativity of any two-mode mixed states can be directly computed from the closed-form formulae given. For multi-mode mixed states, this approach provides a scheme that permits much simpler numerical computation for quantifying

  18. Computational approaches for drug discovery.

    Science.gov (United States)

    Hung, Che-Lun; Chen, Chi-Chun

    2014-09-01

    Cellular proteins are the mediators of multiple organism functions being involved in physiological mechanisms and disease. By discovering lead compounds that affect the function of target proteins, the target diseases or physiological mechanisms can be modulated. Based on knowledge of the ligand-receptor interaction, the chemical structures of leads can be modified to improve efficacy, selectivity and reduce side effects. One rational drug design technology, which enables drug discovery based on knowledge of target structures, functional properties and mechanisms, is computer-aided drug design (CADD). The application of CADD can be cost-effective using experiments to compare predicted and actual drug activity, the results from which can used iteratively to improve compound properties. The two major CADD-based approaches are structure-based drug design, where protein structures are required, and ligand-based drug design, where ligand and ligand activities can be used to design compounds interacting with the protein structure. Approaches in structure-based drug design include docking, de novo design, fragment-based drug discovery and structure-based pharmacophore modeling. Approaches in ligand-based drug design include quantitative structure-affinity relationship and pharmacophore modeling based on ligand properties. Based on whether the structure of the receptor and its interaction with the ligand are known, different design strategies can be seed. After lead compounds are generated, the rule of five can be used to assess whether these have drug-like properties. Several quality validation methods, such as cost function analysis, Fisher's cross-validation analysis and goodness of hit test, can be used to estimate the metrics of different drug design strategies. To further improve CADD performance, multi-computers and graphics processing units may be applied to reduce costs.

  19. Approach to Mars Field Geology

    Science.gov (United States)

    Muehlberger, William; Rice, James W.; Parker, Timothy; Lipps, Jere H.; Hoffman, Paul; Burchfiel, Clark; Brasier, Martin

    1998-01-01

    The goals of field study on Mars are nothing less than to understand the processes and history of the planet at whatever level of detail is necessary. A manned mission gives us an unprecedented opportunity to use the immense power of the human mind to comprehend Mars in extraordinary detail. To take advantage of this opportunity, it is important to examine how we should approach the field study of Mars. In this effort, we are guided by over 200 years of field exploration experience on Earth as well as six manned missions exploring the Moon.

  20. Specialist approaches to managing lipoedema.

    Science.gov (United States)

    Fetzer, Amy

    2016-04-01

    While there is no proven cure for lipoedema, early detection is key as specialist treatments, complemented by self-management techniques, can improve symptoms and prevent progression. There is no universal approach as the correct treatment or treatments will depend on each patient's particular circumstances; however, when chosen early and appropriately, interventions can provide huge benefits. The most common treatments in the management of lipoedema include compression, manual lymphatic drainage (MLD), tumescent liposuction, intermittent pneumatic compression therapy (IPC), kinesio taping, deep oscillation therapy, and cognitive behavioural therapy (CBT).

  1. A Logical Approach to Entanglement

    Science.gov (United States)

    Das, Abhishek

    2016-10-01

    In this paper we innovate a logical approach to develop an intuition regarding the phenomenon of quantum entanglement. In the vein of the logic introduced we substantiate that particles that were entangled in the past will be entangled in perpetuity and thereby abide a rule that restricts them to act otherwise. We also introduce a game and by virtue of the concept of Nash equilibrium we have been able to show that entangled particles will mutually correspond to an experiment that is performed on any one of the particle.

  2. Fundamental approach to discrete mathematics

    CERN Document Server

    Acharjya, DP

    2009-01-01

    About the Book: The book `Fundamental Approach to Discrete Mathematics` is a required part of pursuing a computer science degree at most universities. It provides in-depth knowledge to the subject for beginners and stimulates further interest in the topic. The salient features of this book include: Strong coverage of key topics involving recurrence relation, combinatorics, Boolean algebra, graph theory and fuzzy set theory. Algorithms and examples integrated throughout the book to bring clarity to the fundamental concepts. Each concept and definition is followed by thoughtful examples.

  3. Understanding and Approaching Muslim Visibilities

    DEFF Research Database (Denmark)

    Schmidt, Garbi

    2011-01-01

    of the effects of multiculturalism in larger national debates, a situation affecting research engagement with the community. In the last part of my article I describe my dialogical approaches for engaging with the community, thus situating the article within wider discussions of research self....... Another path, which I pursue here, is to situate the activism of Muslims in the historical fabric of the neighbourhood(s) in which they live, in this case the Copenhagen neighbourhood of Nrrebro. Given that Muslims and others use Nrrebro as they do, this neighbourhood has become a prominent example...

  4. Cognitive reasoning a formal approach

    CERN Document Server

    Anshakov, Oleg M

    2010-01-01

    Dealing with uncertainty, moving from ignorance to knowledge, is the focus of cognitive processes. Understanding these processes and modelling, designing, and building artificial cognitive systems have long been challenging research problems. This book describes the theory and methodology of a new, scientifically well-founded general approach, and its realization in the form of intelligent systems applicable in disciplines ranging from social sciences, such as cognitive science and sociology, through natural sciences, such as life sciences and chemistry, to applied sciences, such as medicine,

  5. Operational gaming an international approach

    CERN Document Server

    Ståhl, Ingolf

    1983-01-01

    Operational Gaming: An International Approach focuses on various research on this method of systems analysis. The text points out the value of this method in decision making, planning, and in the implementation of policies. The book presents a survey that highlights the connection of experimental gaming, game theory, and operational gaming. The value of gaming as a balancing method in assessing multifaceted computer models, most notably about their assumptions on human behavior, is noted. The book also offers an overview of gaming in other countries, such as Bulgaria, Soviet Union, and Japan,

  6. Ermakov approach for minisuperspace oscillators

    CERN Document Server

    Rosu, H C

    1999-01-01

    The WDW equation of arbitrary Hartle-Hawking factor ordering for several minisuperspace universe models, such as the pure gravity FRW and Taub ones, is mapped onto the dynamics of corresponding classical oscillators. The latter ones are studied by the classical Ermakov invariant method, which is a natural aproach in this context. For the more realistic case of a minimally coupled massive scalar field, one can study, within the same type of approach, the corresponding squeezing features as a possible means of describing cosmological evolution. Finally, we comment on the analogy with the accelerator physics

  7. Experimental design a chemometric approach

    CERN Document Server

    Deming, SN

    1987-01-01

    Now available in a paperback edition is a book which has been described as ``...an exceptionally lucid, easy-to-read presentation... would be an excellent addition to the collection of every analytical chemist. I recommend it with great enthusiasm.'' (Analytical Chemistry). Unlike most current textbooks, it approaches experimental design from the point of view of the experimenter, rather than that of the statistician. As the reviewer in `Analytical Chemistry' went on to say: ``Deming and Morgan should be given high praise for bringing the principles of experimental design to the level of the p

  8. Computer Networks A Systems Approach

    CERN Document Server

    Peterson, Larry L

    2011-01-01

    This best-selling and classic book teaches you the key principles of computer networks with examples drawn from the real world of network and protocol design. Using the Internet as the primary example, the authors explain various protocols and networking technologies. Their systems-oriented approach encourages you to think about how individual network components fit into a larger, complex system of interactions. Whatever your perspective, whether it be that of an application developer, network administrator, or a designer of network equipment or protocols, you will come away with a "big pictur

  9. Atomic Approaches to Defect Thermochemistry

    Science.gov (United States)

    1992-04-30

    ATOMIC APPROACHES TO DEFECT THERMOCHEMISTRY (AFOSR-89-0309) for period 1 April 1989 to 31 March 1992 Submitted by Professor James A. Van Vechten and...could be very much less. Thus, the GaAs lattice is indeed found to be stiff. Positron annihilation experiments (17) also teach us that GaAs samples...to be less for Si than for Ge. Experience with chemical trends of bond strengths, as well as the empirical literature, teach us that the H bond

  10. Computational approaches to energy materials

    CERN Document Server

    Catlow, Richard; Walsh, Aron

    2013-01-01

    The development of materials for clean and efficient energy generation and storage is one of the most rapidly developing, multi-disciplinary areas of contemporary science, driven primarily by concerns over global warming, diminishing fossil-fuel reserves, the need for energy security, and increasing consumer demand for portable electronics. Computational methods are now an integral and indispensable part of the materials characterisation and development process.   Computational Approaches to Energy Materials presents a detailed survey of current computational techniques for the

  11. Formalistic approaches to A & P

    Institute of Scientific and Technical Information of China (English)

    赵倩

    2014-01-01

    A&P is a famous short story. Its simple words, the unique point of view and skillful writing technique are expressed successfully. Besides, the first-person narrator is also a good point. From Sammy’s eyes, readers can learn the character’s characteristics. Another point is the usage of symbol, the name of the store, A&P, it shows that people’s life is rich, but their spirit is barren. This article tries to analyze it by formalistic approaches.

  12. Real Analysis A Historical Approach

    CERN Document Server

    Stahl, Saul

    2011-01-01

    A provocative look at the tools and history of real analysis This new edition of Real Analysis: A Historical Approach continues to serve as an interesting read for students of analysis. Combining historical coverage with a superb introductory treatment, this book helps readers easily make the transition from concrete to abstract ideas. The book begins with an exciting sampling of classic and famous problems first posed by some of the greatest mathematicians of all time. Archimedes, Fermat, Newton, and Euler are each summoned in turn, illuminating the utility of infinite, power, and trigonome

  13. Location theory a unified approach

    CERN Document Server

    Nickel, Stefan

    2006-01-01

    Although modern location theory is now more than 90 years old, the focus of researchers in this area has been mainly problem oriented. However, a common theory, which keeps the essential characteristics of classical location models, is still missing.This monograph addresses this issue. A flexible location problem called the Ordered Median Problem (OMP) is introduced. For all three main subareas of location theory (continuous, network and discrete location) structural properties of the OMP are presented and solution approaches provided. Numerous illustrations and examples help the reader to bec

  14. Fission approach to cluster radioactivity

    Indian Academy of Sciences (India)

    D N Poenaru; R A Gherghescu

    2015-09-01

    Fission theory is used to explain decay. Also, the analytical superasymmetric fission (ASAF) model is successfully employed to make a systematic search and to predict, with other models, cluster radioactivity. The macroscopic–microscopic method is illustrated for the superheavy nucleus 286Fl. Then a few results of the theoretical approach of decay (ASAF, UNIV and semFIS models), cluster decay (ASAF and UNIV) and spontaneous fission dynamics are described with Werner–Wheeler and cranking inertia. UNIV denotes universal curve and semFIS the fission-based semiempirical formula.

  15. Orthodontic-periodontics interdisciplinary approach.

    Science.gov (United States)

    Vinod, K; Reddy, Y Giridhar; Reddy, Vinay P; Nandan, Hemant; Sharma, Meenakshi

    2012-01-01

    In this present era, when a significant number of patients seeking orthodontic treatment are adults, importance of multidisciplinary treatment approach cannot be overemphasized. Higher susceptibility of plaque accumulation in patients undergoing orthodontic treatment makes involvement of periodontist almost unavoidable. Also, orthodontic treatment frequently results in undesirable periodontal changes which require immediate attention. More recently, orthodontics has been used as an adjunct to periodontics to increase connective tissue support and alveolar bone height. The purpose of this article is to review the adverse effects of orthodontic treatment on the periodontal tissues and to discuss the mutually beneficial relationship shared between the two specialties.

  16. Nanothermodynamics: a subdivision potential approach

    Directory of Open Access Journals (Sweden)

    R. Moussavi

    2005-12-01

    Full Text Available  Classical thermodynamic laws and relations have been developed for macroscopic systems that satisfy the thermodynamic limit. These relations are challenged as the system size decreases to the scale of nano-systems, in which thermodynamic properties are overshadowed by system size, and the usual classical concepts of extensivity and intensivity are no longer valid. The challenges to the classical thermodynamics in relation to small systems are demonstrated, and via the approach introduced by Hill, the concept of sub-division potential is clarified in details. The fundamental thermodynamic relations are obtained using a rational-based method.

  17. The calculus a genetic approach

    CERN Document Server

    Toeplitz, Otto

    2007-01-01

    When first published posthumously in 1963, this book presented a radically different approach to the teaching of calculus.  In sharp contrast to the methods of his time, Otto Toeplitz did not teach calculus as a static system of techniques and facts to be memorized. Instead, he drew on his knowledge of the history of mathematics and presented calculus as an organic evolution of ideas beginning with the discoveries of Greek scholars, such as Archimedes, Pythagoras, and Euclid, and developing through the centuries in the work of Kepler, Galileo, Fermat, Newton, and Leibniz. Through this unique a

  18. 'Lean' approach gives greater efficiency.

    Science.gov (United States)

    Call, Roger

    2014-02-01

    Adapting the 'Lean' methodologies used for many years by many manufacturers on the production line - such as in the automotive industry - and deploying them in healthcare 'spaces' can, Roger Call, an architect at Herman Miller Healthcare in the US, argues, 'easily remedy many of the inefficiencies' found within a healthcare facility. In an article that first appeared in the September 2013 issue of The Australian Hospital Engineer, he explains how 'Lean' approaches such as the 'Toyota production system', and 'Six Sigma', can be harnessed to good effect in the healthcare sphere.

  19. Educational approaches for discouraging plagiarism.

    Science.gov (United States)

    Fischer, Beth A; Zigmond, Michael J

    2011-01-01

    Suggested approaches to reduce the occurrence of plagiarism in academia, particularly among trainees. These include (1) educating individuals as to the definition of plagiarism and its consequences through written guidelines, active discussions, and practice in identifying proper and improper citation practices; (2) distributing checklists that break the writing task into more manageable steps, (3) requiring the submission of an outline and then a first draft prior to the deadline for a paper; (4) making assignments relevant to individual interests; and (5) providing trainees with access to software programs that detect plagiarism.

  20. A new approach to magic

    Directory of Open Access Journals (Sweden)

    Čvorović Jelena

    2006-01-01

    Full Text Available This paper uses the example of traditional practices of magic to suggest ways to incorporate cultural behaviors within the evolutionary paradigm. The first suggestion is to restrict hypotheses to only identifiable variables. This means avoiding the temptation of following the nonevolutionary social sciences in the practice of basing explanations on unverifiable guesses about what beliefs (or memes in evolutionary jargon may or may not inhabit people's brains. In contrast with previous explanations that magical practices result from beliefs and memes whose primarily purpose is to reduce anxiety, we propose that magic is a form of communication that promotes cooperation and often avoids anti-social behavior. This effect of increased cooperation could explain why traditional forms of magic have probably existed and had significant positive consequences for the participants. To be effective as a means of communication, magical rituals must specify both the content of the message and the receiver of the message. Although the content of the communicative message differs with different types of magic, all magical acts serve a purpose to influence the behavior of the party involved and that is the most significant identifiable effect of such behavior. An advantage of this approach over many previous explanations of magic is that because it focuses on identifiable phenomena, the definitions and explanations used in this approach can be falsified.

  1. Approach/avoidance in dreams.

    Science.gov (United States)

    Malcolm-Smith, Susan; Koopowitz, Sheri; Pantelis, Eleni; Solms, Mark

    2012-03-01

    The influential threat simulation theory (TST) asserts that dreaming yields adaptive advantage by providing a virtual environment in which threat-avoidance may be safely rehearsed. We have previously found the incidence of biologically threatening dreams to be around 20%, with successful threat avoidance occurring in approximately one-fifth of such dreams. TST asserts that threat avoidance is over-represented relative to other possible dream contents. To begin assessing this issue, we contrasted the incidence of 'avoidance' dreams with that of their opposite: 'approach' dreams. Because TST states that the threat-avoidance function is only fully activated in ecologically valid (biologically threatening) contexts, we also performed this contrast for populations living in both high- and low-threat environments. We find that 'approach' dreams are significantly more prevalent across both contexts. We suggest these results are more consistent with the view that dreaming is generated by reward-seeking systems than by fear-conditioning systems, although reward-seeking is clearly not the only factor determining the content of dreams.

  2. Systematic approach to thermal leptogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Frossard, T.; Kartavtsev, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Garny, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Hohenegger, A. [Ecole Polytechnique Federale de Lausanne, LPPC, BSP (Switzerland); Mitrouskas, D. [Muenchen Univ. (Germany)

    2012-11-15

    In this work we study thermal leptogenesis using non-equilibrium quantum field theory. Starting from fundamental equations for correlators of the quantum fields we describe the steps necessary to obtain quantum kinetic equations for quasiparticles. These can easily be compared to conventional results and overcome conceptional problems inherent in the canonical approach. Beyond CP-violating decays we include also those scattering processes which are tightly related to the decays in a consistent approximation of fourth order in the Yukawa couplings. It is demonstrated explicitly how the S-matrix elements for the scattering processes in the conventional approach are related to two- and three-loop contributions to the effective action. We derive effective decay and scattering amplitudes taking medium corrections and thermal masses into account. In this context we also investigate CP-violating Higgs decay within the same formalism. From the kinetic equations we derive rate equations for the lepton asymmetry improved in that they include quantum-statistical effects and medium corrections to the quasiparticle properties.

  3. Interdisciplinary Approach in Engineering Education

    Directory of Open Access Journals (Sweden)

    Anda Zeidmane

    2011-04-01

    Full Text Available The analysis of the scientific literature available on the types of general competences and their classification caused the authors to conclude that it is necessary to implement interdisciplinary approach in engineering education to develop competences necessary for engineers to make them competitive in the labour market. The attention should be paid to a professional foreign language, computer literacy and educational psychology recommendations. To improve professional foreign language skills, CLIL (Content and Language Integrated Learning method should be integrated in the study process of engineering education. In order to develop information literacy competence, it is important to create a single e-study environment. The academic staff, developing study subjects for engineering programmes, should focus on the study content and study methods. As regards the content, the compromise should be sought between fundamental acquisition of the knowledge of the subject matter, the know-how of the application of this knowledge as well as the use of brand new software in the calculations. The paper presents the examples of the application of the interdisciplinary approach in the universities, where the authors of the paper are affiliated: the LUA (Latvia University of Agriculture and the RTU (Riga Technical University, respectively.

  4. Cardiac imaging. A multimodality approach

    Energy Technology Data Exchange (ETDEWEB)

    Thelen, Manfred [Johannes Gutenberg University Hospital, Mainz (Germany); Erbel, Raimund [University Hospital Essen (Germany). Dept. of Cardiology; Kreitner, Karl-Friedrich [Johannes Gutenberg University Hospital, Mainz (Germany). Clinic and Polyclinic for Diagnostic and Interventional Radiology; Barkhausen, Joerg (eds.) [University Hospital Schleswig-Holstein, Luebeck (Germany). Dept. of Radiology and Nuclear Medicine

    2009-07-01

    An excellent atlas on modern diagnostic imaging of the heart Written by an interdisciplinary team of experts, Cardiac Imaging: A Multimodality Approach features an in-depth introduction to all current imaging modalities for the diagnostic assessment of the heart as well as a clinical overview of cardiac diseases and main indications for cardiac imaging. With a particular emphasis on CT and MRI, the first part of the atlas also covers conventional radiography, echocardiography, angiography and nuclear medicine imaging. Leading specialists demonstrate the latest advances in the field, and compare the strengths and weaknesses of each modality. The book's second part features clinical chapters on heart defects, endocarditis, coronary heart disease, cardiomyopathies, myocarditis, cardiac tumors, pericardial diseases, pulmonary vascular diseases, and diseases of the thoracic aorta. The authors address anatomy, pathophysiology, and clinical features, and evaluate the various diagnostic options. Key features: - Highly regarded experts in cardiology and radiology off er image-based teaching of the latest techniques - Readers learn how to decide which modality to use for which indication - Visually highlighted tables and essential points allow for easy navigation through the text - More than 600 outstanding images show up-to-date technology and current imaging protocols Cardiac Imaging: A Multimodality Approach is a must-have desk reference for cardiologists and radiologists in practice, as well as a study guide for residents in both fields. It will also appeal to cardiac surgeons, general practitioners, and medical physicists with a special interest in imaging of the heart. (orig.)

  5. Molecular Approaches to Studying Denitrification

    Science.gov (United States)

    Voytek, M. A.

    2001-05-01

    Denitrification is carried out by a diverse array of microbes, mainly as an alternative mode of respiration that allows the organisms to respire using oxidized N compounds instead of oxygen. A common approach in biogeochemistry to the study of the regulation of denitrification is to assess activity by mass balance of substrates and products or direct rate measurements and has intrinsically assumed resource regulation of denitrification. Reported rates can vary significantly even among ecosystems characterized by similar environmental conditions, thus indicating that direct control by abiotic factors often is not sufficient to predict denitrification rates accurately in natural environments. Alternatively, a microbiological approach would proceed with the identification of the organisms responsible and an evaluation of the effect of environmental factors on the biochemical pathways involved. Traditional studies have relied on culturing techniques, such as most probable number enrichments, and have failed to assess the role of the predominately uncultivable members of the microbial community. A combination of biogeochemical measurements and the assessment of the microbial community is necessary and becoming increasingly possible with the development and application of molecular techniques. In order to understand how the composition and physiological behavior of the microbial community affects denitrification rates, we use a suite of molecular techniques developed for phylogenetic and metabolic characterization of denitrifying communities. Molecular tools available for quantifying denitrifying bacteria and assessing their diversity and activity are summarized. Their application is illustrated with examples from marine and freshwater environments. Emerging techniques and their application to ground water studies will be discussed.

  6. Theoretical approaches to superionic conductivity

    Indian Academy of Sciences (India)

    C S Sunandana; P Senthil Kumar

    2004-02-01

    Recent theoretical approaches to the understanding of superionic conductivity in polycrystalline, glassy and polymeric materials are briefly reviewed. Phase transitions to the superionic conducting state in the AgI family are apparently triggered by cluster formation and strong mobile ion interaction within the clusters. Anomalous conductivity and related physical properties are explained in the cluster induced distortion model. Ionic composites such as AgX : Al2O3 ( = Cl, Br and I) involve conducting and non-conducting phases and the all-important interface between the two whose space charge enhances the conductivity and also trigger phase transitions to exotic polymorphic phases, for which the mechanisms are yet to be explored. Ion hopping dynamics controls the conductivity of superionic glasses. Mode coupling and jump relaxation theories account for the non-Debye relaxation observed in a.c. conductivity of these glasses. The theory of conductivity in polymer electrolytes-still in its infancy-involves their complex structure and glass transition behaviour. Preparative and thermal history, composition and crystallinity control ionic conductivity. New approaches to the synthesis of optimal polymer electrolytes such as rubbery electrolytes, crystalline polymers and nanocomposites must be considered before achieving a comprehensive theoretical understanding.

  7. Phonetic Ambiguity Approaches, Touchstones, Pitfalls and New Approaches

    CERN Document Server

    Juola, P

    1996-01-01

    Phonetic ambiguity and confusibility are bugbears for any form of bottom-up or data-driven approach to language processing. The question of when an input is ``close enough'' to a target word pervades the entire problem spaces of speech recognition, synthesis, language acquisition, speech compression, and language representation, but the variety of representations that have been applied are demonstrably inadequate to at least some aspects of the problem. This paper reviews this inadequacy by examining several touchstone models in phonetic ambiguity and relating them to the problems they were designed to solve. An good solution would be, among other things, efficient, accurate, precise, and universally applicable to representation of words, ideally usable as a ``phonetic distance'' metric for direct measurement of the ``distance'' between word or utterance pairs. None of the proposed models can provide a complete solution to the problem; in general, there is no algorithmic theory of phonetic distance. It is unc...

  8. Bruxism and Current Treatment Approaches

    Directory of Open Access Journals (Sweden)

    Selin Eren

    2016-06-01

    Full Text Available Among the mastication system disorders bruxism is a parafunctional behavior that comes from psychophysiological origin. Epidemiologic studies have reported great variability of bruxism prevalence. The factors that could cause bruxism is highly controversial. There are different opinions on this issue. The etiologic factors of bruxism include stress, malnutrition, allergic and endocrinologic diseases, central nervous system disorders, genetic factors, medicines, malocclusion, and wrong dental treatment. The aim of treatment of bruxism is to prevent damage that may occur on teeth and in the temporomandibular joint and to eliminate pain. Dental treatment, physical therapy, pharmacological treatment and behavioral and cognitive therapy can be considered for this purpose of treatment. This review summarizes the etiologic factors, epidemiology, diagnosis, and current treatment approaches of patient with bruxism. [Archives Medical Review Journal 2016; 25(2.000: 241-258

  9. A tauberian approach to RH

    CERN Document Server

    Cloitre, Benoit

    2011-01-01

    The aim of this paper is twofold. Firstly we present our main discovery arising from experiments which is the tauberian concept of functions of good variation (FGV). Secondly we propose to use these FGV for proving RH is true via some conjectures. More precisely we give an implicit definition of FGV and we provide several smooth and nontrivial exemples from experiments. Then using a conjectured family of FGV involving functions approaching the floor function we derive RH is true. We make also a tauberian conjecture allowing us to prove RH is true for L-functions (the generalized RH) and automorphic L-functions (the grand RH) and we discuss the linear independance conjecture. The method is inspired by the Ingham summation process and the experimental support is provided using pari-gp.

  10. Analytic Approach to Perturbative QCD

    CERN Document Server

    Magradze, B

    2000-01-01

    The two-loop invariant (running) coupling of QCD is written in terms of the Lambert W function. The analyticity structure of the coupling in the complex Q^2-plane is established. The corresponding analytic coupling is reconstructed via a dispersion relation. We also consider some other approximations to the QCD beta-function, when the corresponding couplings are solved in terms of the Lambert function. The Landau gauge gluon propagator has been considered in the renormalization group invariant analytic approach (IAA). It is shown that there is a nonperturbative ambiguity in determination of the anomalous dimension function of the gluon field. Several analytic solutions for the propagator at the one-loop order are constructed. Properties of the obtained analytical solutions are discussed.

  11. Diffraction operators in paraxial approach

    Science.gov (United States)

    Lasso, William; Navas, Marianela; Añez, Liz; Urdaneta, Romer; Díaz, Leonardo; Torres, César O.

    2014-07-01

    Nowadays, research in the field of science education points to the creation of alternative ways of teaching contents encouraging the development of more elaborate reasoning, where a high degree of abstraction and generalization of scientific knowledge prevails. On that subject, this research shows a didactic alternative proposal for the construction of Fresnel and Fraunhoffer diffraction concepts applying the Fourier transform technique in the study of electromagnetic waves propagation in free space. Curvature transparency and Fourier sphere operators in paraxial approximation are used in order to make the usual laborious mathematical approach easier. The main result shows that the composition of optic metaxial operators results in the discovery of a simpler way out of the standard electromagnetic wave propagation in free space between a transmitter and a receptor separated from a given distance. This allows to state that the didactic proposal shown encourages the construction of Fresnel and Fraunhoffer diffraction concepts in a more effective and easier way than the traditional teaching.

  12. A Diagnostic Approach to Hemochromatosis

    Directory of Open Access Journals (Sweden)

    Anthony S Tavill

    2006-01-01

    Full Text Available In the present clinical review, a diagnostic approach to hemochromatosis is discussed from the perspective of two clinicians with extensive experience in this area. The introduction of genetic testing and large-scale population screening studies have broadened our understanding of the clinical expression of disease and the utility of biochemical iron tests for the detection of disease and for the assessment of disease severity. Liver biopsy has become more of a prognostic test than a diagnostic test. The authors offer a stepwise, diagnostic algorithm based on current evidence-based data, that they regard as most cost-effective. An early diagnosis can lead to phlebotomy therapy to prevent the development of cirrhosis.

  13. Gaze disorders: A clinical approach

    Directory of Open Access Journals (Sweden)

    Pulikottil Wilson Vinny

    2016-01-01

    Full Text Available A single clear binocular vision is made possible by the nature through the oculomotor system along with inputs from the cortical areas as well their descending pathways to the brainstem. Six systems of supranuclear control mechanisms play a crucial role in this regard. These are the saccadic system, the smooth pursuit system, the vestibular system, the optokinetic system, the fixation system, and the vergence system. In gaze disorders, lesions at different levels of the brain spare some of the eye movement systems while affecting others. The resulting pattern of eye movements helps clinicians to localize lesions accurately in the central nervous system. Common lesions causing gaze palsies include cerebral infarcts, demyelinating lesions, multiple sclerosis, tumors, Wernicke's encephalopathy, metabolic disorders, and neurodegenerative disorders such as progressive supranuclear palsy. Evaluation of the different gaze disorders is a bane of most budding neurologists and neurosurgeons. However, a simple and systematic clinical approach to this problem can make their early diagnosis rather easy.

  14. Raman spectroscopy an intensity approach

    CERN Document Server

    Guozhen, Wu

    2017-01-01

    This book summarizes the highlights of our work on the bond polarizability approach to the intensity analysis. The topics covered include surface enhanced Raman scattering, Raman excited virtual states and Raman optical activity (ROA). The first chapter briefly introduces the Raman effect in a succinct but clear way. Chapter 2 deals with the normal mode analysis. This is a basic tool for our work. Chapter 3 introduces our proposed algorithm for the Raman intensity analysis. Chapter 4 heavily introduces the physical picture of Raman virtual states. Chapter 5 offers details so that the readers can have a comprehensive idea of Raman virtual states. Chapter 6 demonstrates how this bond polarizability algorithm is extended to ROA intensity analysis. Chapters 7 and 8 offer details on ROA, showing many findings on ROA mechanism that were not known or neglected before. Chapter 9 introduces our proposed classical treatment on ROA which, as combined with the results from the bond polarizability analysis, leads to a com...

  15. Carious dentine removal: current approach

    Directory of Open Access Journals (Sweden)

    Germana Coeli de Farias Sales

    2008-01-01

    Full Text Available Dentistry is renewed day after day through the results of qualified researches. The approach as regards carious dentin removal is goingthrough questioning and innovation. The scope of this study was to perform a literature review in the sense of elucidating questions pertaining to the problem of whether or not it is necessary to completely remove carious dentin, and the possibility of performing restoration in a single session, in addition to a discussion about which type of material should be applied in this type of substrate. After analyzing the referenced articles, it was concluded that the stepwise treatment controls caries progression; there is a trend in the literature to partially remove the carious dentin in deep lesions and perform definitive restoration; Calcium hydroxide cement is a classical liner in these situations, while glass ionomer cement and resinous materials are other possibilities of materials that can be in close contact with the remaining dentin.

  16. Mindful approach to University education

    Science.gov (United States)

    Broggi, Fiorenza; Bomba, Monica; Rimondini, Michela; Mutti, Maura; Pasta, Sara; Ricci, Chiara; Tagliabue, Luca; Valsecchi, Silvia; Monaco, Elide; Neri, Francesca; Oggiano, Silvia; Nacinovich, Renata

    2016-01-01

    A mindful approach to education and training could improve students’ reflective capacities and have positive effects on clinical practice because it facilitates a helping relationship. The main aims of this study were to investigate whether participation in a mindful-based University training was associated with increases in mindfulness skills as measured by the 5-Facet M Questionnaire, and to present the Italian validation of the questionnaire. Sixty-seven students from the course Neuro and Psychomotor Therapy were enrolled. They filled in the self-administered 5-Facet M Questionnaire before and 1 month after a mindfulness-based training, focused on role-playing and followed by a feedback group discussion. The Italian version of the 5-Facet M Questionnaire had good psychometric properties. The pre- and post-training analysis showed a significant increase in the subscale ‘Observing’. Findings suggest that role-playing and feedback group sessions are valid tools to improve students’ mindfulness skills. PMID:27729823

  17. AN INTERACTIVE APPROACH TO READING

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    Introduction The Sino-British Friendship Scholarship Scheme (SBFSS) is co-sponsored by the Chinese and British governments and Sir Yue-gang Pao in Hong Kong to send Chinese scholars to study in Britain. Each year a large number of candidates are selected by the State Education Commission and dispatched to three intensive language training centres attached to Beijing Languages Institute, Shanghai Foreign Studies University and Chengdu University of Science and Technology for pre-departure ELT training. At the end of the training period, the trainees are required to take the International English Language Testing System (IELTS) test administered by the British side. Here at CUST, we focus on an interactive approach to training, particularly for reading.

  18. Queueing networks a fundamental approach

    CERN Document Server

    Dijk, Nico

    2011-01-01

    This handbook aims to highlight fundamental, methodological and computational aspects of networks of queues to provide insights and to unify results that can be applied in a more general manner.  The handbook is organized into five parts: Part 1 considers exact analytical results such as of product form type. Topics include characterization of product forms by physical balance concepts and simple traffic flow equations, classes of service and queue disciplines that allow a product form, a unified description of product forms for discrete time queueing networks, insights for insensitivity, and aggregation and decomposition results that allow subnetworks to be aggregated into single nodes to reduce computational burden. Part 2 looks at monotonicity and comparison results such as for computational simplification by either of two approaches: stochastic monotonicity and ordering results based on the ordering of the proces generators, and comparison results and explicit error bounds based on an underlying Markov r...

  19. Automated Approaches to RFI Flagging

    Science.gov (United States)

    Garimella, Karthik; Momjian, Emmanuel

    2017-01-01

    It is known that Radio Frequency Interference (RFI) is a major issue in centimeter wavelength radio astronomy. Radio astronomy software packages include tools to excise RFI; both manual and automated utilizing the visibilities (the uv data). Here we present results on an automated RFI flagging approach that utilizes a uv-grid, which is the intermediate product when converting uv data points to an image. It is a well known fact that any signal that appears widespread in a given domain (e.g., image domain) is compact in the Fourier domain (uv-grid domain), i.e., RFI sources that appear as large scale structures (e.g., stripes) in images can be located and flagged using the uv-grid data set. We developed several automated uv-grid based flagging algorithms to detect and excise RFI. These algorithms will be discussed, and results of applying them to measurement sets will be presented.

  20. Steganography and Steganalysis: Different Approaches

    CERN Document Server

    Das, Soumyendu; Bandyopadhyay, Bijoy; Sanyal, Sugata

    2011-01-01

    Steganography is the technique of hiding confidential information within any media. Steganography is often confused with cryptography because the two are similar in the way that they both are used to protect confidential information. The difference between the two is in the appearance in the processed output; the output of steganography operation is not apparently visible but in cryptography the output is scrambled so that it can draw attention. Steganlysis is process to detect of presence of steganography. In this article we have tried to elucidate the different approaches towards implementation of steganography using 'multimedia' file (text, static image, audio and video) and Network IP datagram as cover. Also some methods of steganalysis will be discussed.

  1. Semiclassical approaches to nuclear dynamics

    CERN Document Server

    Magner, A G; Bartel, J

    2016-01-01

    The extended Gutzwiller trajectory approach is presented for the semiclassical description of nuclear collective dynamics, in line with the main topics of the fruitful activity of V.G. Solovjov. Within the Fermi-liquid droplet model, the leptodermous effective surface approximation was applied to calculations of energies, sum rules and transition densities for the neutron-proton asymmetry of the isovector giant-dipole resonance and found to be in good agreement with the experimental data. By using the Strutinsky shell correction method, the semiclassical collective transport coefficients such as nuclear inertia, friction, stiffness, and moments of inertia can be derived beyond the quantum perturbation approximation of the response function theory and the cranking model.The averaged particle-number dependence of the low-lying collective vibrational states are described in good agreement with basic experimental data, mainly due to an enhancement of the collective inertia as compared to its irrotational flow val...

  2. A Hamiltonian approach to Thermodynamics

    CERN Document Server

    Baldiotti, M C; Molina, C

    2016-01-01

    In the present work we develop a strictly Hamiltonian approach to Thermodynamics. A thermodynamic description based on symplectic geometry is introduced, where all thermodynamic processes can be described within the framework of Analytic Mechanics. Our proposal is constructed ontop of a usual symplectic manifold, where phase space is even dimensional and one has well-defined Poisson brackets. The main idea is the introduction of an extended phase space where thermodynamic equations of state are realized as constraints. We are then able to apply the canonical transformation toolkit to thermodynamic problems. Throughout this development, Dirac's theory of constrained systems is extensively used. To illustrate the formalism, we consider paradigmatic examples, namely, the ideal, van der Waals and Clausius gases.

  3. Statistical Physics Approaches to Seismicity

    CERN Document Server

    Sornette, D

    2008-01-01

    This entry in the Encyclopedia of Complexity and Systems Science, Springer present a summary of some of the concepts and calculational tools that have been developed in attempts to apply statistical physics approaches to seismology. We summarize the leading theoretical physical models of the space-time organization of earthquakes. We present a general discussion and several examples of the new metrics proposed by statistical physicists, underlining their strengths and weaknesses. The entry concludes by briefly outlining future directions. The presentation is organized as follows. I Glossary II Definition and Importance of the Subject III Introduction IV Concepts and Calculational Tools IV.1 Renormalization, Scaling and the Role of Small Earthquakes in Models of Triggered Seismicity IV.2 Universality IV.3 Intermittent Periodicity and Chaos IV.4 Turbulence IV.5 Self-Organized Criticality V Competing mechanisms and models V.1 Roots of complexity in seismicity: dynamics or heterogeneity? V.2 Critical earthquakes ...

  4. Ontology Partitioning: Clustering Based Approach

    Directory of Open Access Journals (Sweden)

    Soraya Setti Ahmed

    2015-05-01

    Full Text Available The semantic web goal is to share and integrate data across different domains and organizations. The knowledge representations of semantic data are made possible by ontology. As the usage of semantic web increases, construction of the semantic web ontologies is also increased. Moreover, due to the monolithic nature of the ontology various semantic web operations like query answering, data sharing, data matching, data reuse and data integration become more complicated as the size of ontology increases. Partitioning the ontology is the key solution to handle this scalability issue. In this work, we propose a revision and an enhancement of K-means clustering algorithm based on a new semantic similarity measure for partitioning given ontology into high quality modules. The results show that our approach produces meaningful clusters than the traditional algorithm of K-means.

  5. A programming approach to computability

    CERN Document Server

    Kfoury, A J; Arbib, Michael A

    1982-01-01

    Computability theory is at the heart of theoretical computer science. Yet, ironically, many of its basic results were discovered by mathematical logicians prior to the development of the first stored-program computer. As a result, many texts on computability theory strike today's computer science students as far removed from their concerns. To remedy this, we base our approach to computability on the language of while-programs, a lean subset of PASCAL, and postpone consideration of such classic models as Turing machines, string-rewriting systems, and p. -recursive functions till the final chapter. Moreover, we balance the presentation of un solvability results such as the unsolvability of the Halting Problem with a presentation of the positive results of modern programming methodology, including the use of proof rules, and the denotational semantics of programs. Computer science seeks to provide a scientific basis for the study of information processing, the solution of problems by algorithms, and the design ...

  6. Entropy: The Markov Ordering Approach

    Directory of Open Access Journals (Sweden)

    Alexander N. Gorban

    2010-05-01

    Full Text Available The focus of this article is on entropy and Markov processes. We study the properties of functionals which are invariant with respect to monotonic transformations and analyze two invariant “additivity” properties: (i existence of a monotonic transformation which makes the functional additive with respect to the joining of independent systems and (ii existence of a monotonic transformation which makes the functional additive with respect to the partitioning of the space of states. All Lyapunov functionals for Markov chains which have properties (i and (ii are derived. We describe the most general ordering of the distribution space, with respect to which all continuous-time Markov processes are monotonic (the Markov order. The solution differs significantly from the ordering given by the inequality of entropy growth. For inference, this approach results in a convex compact set of conditionally “most random” distributions.

  7. Two Approaches to Entrepreneurship Education

    DEFF Research Database (Denmark)

    Moberg, Kåre

    2014-01-01

    and focuses on fostering non-cognitive entrepreneurial skills. Furthermore, the role of supportive teaching styles and action-based teaching methods in entrepreneurship education at this level of education is investigated. The analysis is based on data from two surveys including 801 randomly selected Danish......The objective of this paper is to analyse the influence of two different approaches to entrepreneurship education at the lower secondary level of education. The influence of education for entrepreneurship and education through entrepreneurship on pupils' level of school engagement...... for entrepreneurship, which focuses on content and cognitive entrepreneurial skills, has a positive influence on pupils' entrepreneurial intentions but a negative influence on their level of school engagement. The opposite is true for education through entrepreneurship, which has a more pedagogical orientation...

  8. Computational approach to Riemann surfaces

    CERN Document Server

    Klein, Christian

    2011-01-01

    This volume offers a well-structured overview of existent computational approaches to Riemann surfaces and those currently in development. The authors of the contributions represent the groups providing publically available numerical codes in this field. Thus this volume illustrates which software tools are available and how they can be used in practice. In addition examples for solutions to partial differential equations and in surface theory are presented. The intended audience of this book is twofold. It can be used as a textbook for a graduate course in numerics of Riemann surfaces, in which case the standard undergraduate background, i.e., calculus and linear algebra, is required. In particular, no knowledge of the theory of Riemann surfaces is expected; the necessary background in this theory is contained in the Introduction chapter. At the same time, this book is also intended for specialists in geometry and mathematical physics applying the theory of Riemann surfaces in their research. It is the first...

  9. Autobot Evolution: A Futuristic approach

    Directory of Open Access Journals (Sweden)

    N.Hariharan#

    2011-06-01

    Full Text Available SCABOR is an approach for the 3-D lane detection and autonomous driving. Its main attribute is to diagnose the metrology of roads. It has a wide significance in determining the basic structure, the presence of humps and dips and gives a clear and cache information of the way .Our view on this paper is to apply SCABOR along with the application of the GLOBAL POSITIONING SYSTEM in autonomous driving system for safe and fast driving. Here the SCABOR technology’s currentapplication is outlined and its use has been extended to traffic system. We have suggested a unique method for flexible driving. We also suggest ways in which SCABOR technology can be enhanced forfuture applications. Among the significant advantages, these techniques perform well even in high risk zones and congested areas with up to 100% accuracy where many other techniques fail.

  10. Approaching Environmental Issues in Architecture

    DEFF Research Database (Denmark)

    Petersen, Mads Dines; Knudstrup, Mary-Ann

    2013-01-01

    The research presented here takes its point of departure in the design process with a specific focus on how it is approached when designing energy efficient architecture. This is done through a case-study of a design process in a Danish architectural office. This study shows the importance...... of having a clear strategy about how to work with optimizing the energy efficiency in the building from the first stages of the design process. It is not just a task that can be addressed by the engineers when a concept has been developed and approved by the client. It requires architects and engineers...... to address it from the beginning and work actively with it, but it also requires the client to state it clearly in the brief. From this study, it is evident that the work with energy efficiency requires us to focus on the formal framework for the design process. It must allow and support a multi...

  11. Approaches to translational plant science

    DEFF Research Database (Denmark)

    Dresbøll, Dorte Bodin; Christensen, Brian; Thorup-Kristensen, Kristian

    2015-01-01

    Translational science deals with the dilemma between basic research and the practical application of scientific results. In translational plant science, focus is on the relationship between agricultural crop production and basic science in various research fields, but primarily in the basic plant...... science. Scientific and technological developments have allowed great progress in our understanding of plant genetics and molecular physiology, with potentials for improving agricultural production. However, this development has led to a separation of the laboratory-based research from the crop production...... is lessened. In our opinion, implementation of translational plant science is a necessity in order to solve the agricultural challenges of producing food and materials in the future. We suggest an approach to translational plant science forcing scientists to think beyond their own area and to consider higher...

  12. Pharmacotherapy of Schizophrenia: Ploypharmacy Approaches

    Directory of Open Access Journals (Sweden)

    Fatemeh Rahiminejad

    2010-07-01

    Full Text Available "nSchizophrenia is a debilitating illness, rating as one of the leading causes of lost years of quality of life. The illness imposes a disproportionate burden on patients and their families, healthcare systems and society. Pharmacological management is the cornerstone of treatment of schizophrenia, and antipsychotics, both first generation of antipsychotics and second generation of antipsychotics, are efficacious in reducing levels of psychopathology in acute episodes of schizophrenia. Clearly a need for innovative treatment strategies in schizophrenia that will ensure increased effectiveness against negative symptoms and cognitive dysfunction dysfunction. Therefore, in majority of cases polypharmacy is one of the effective approaches. This review focused on polypharmacy in the treatment of schizophrenia and in particular negative symptoms.

  13. Emerging approaches in predictive toxicology.

    Science.gov (United States)

    Zhang, Luoping; McHale, Cliona M; Greene, Nigel; Snyder, Ronald D; Rich, Ivan N; Aardema, Marilyn J; Roy, Shambhu; Pfuhler, Stefan; Venkatactahalam, Sundaresan

    2014-12-01

    Predictive toxicology plays an important role in the assessment of toxicity of chemicals and the drug development process. While there are several well-established in vitro and in vivo assays that are suitable for predictive toxicology, recent advances in high-throughput analytical technologies and model systems are expected to have a major impact on the field of predictive toxicology. This commentary provides an overview of the state of the current science and a brief discussion on future perspectives for the field of predictive toxicology for human toxicity. Computational models for predictive toxicology, needs for further refinement and obstacles to expand computational models to include additional classes of chemical compounds are highlighted. Functional and comparative genomics approaches in predictive toxicology are discussed with an emphasis on successful utilization of recently developed model systems for high-throughput analysis. The advantages of three-dimensional model systems and stem cells and their use in predictive toxicology testing are also described.

  14. Topological approach of Jungian psychology.

    Science.gov (United States)

    Viret, Jacques

    2010-09-01

    In this work, we compare two global approaches which are usually considered as completely unconnected one with the other. The former is Thom's topology and the latter is Jung's psychology. More precisely, it seemed to us interesting to adapt some morphologies of Thom's catastrophe theory to some Jung's notions. Thus, we showed that the swallowtail, which is one of these morphologies, was able to describe geometrically the structural organisation of the psyche according to Jung, with its collective unconscious, personal unconscious and conscious. Moreover, we have correlated this morphology with Jung's evolutive processes like individualization and individuation. These comparisons incited us to think that some morphologies of Thom's catastrophe theory are the geometrical dealing of Jung's archetypes.

  15. Managerial Leadership - A Theoretical Approach

    Directory of Open Access Journals (Sweden)

    Felicia Cornelia MACARIE

    2007-06-01

    Full Text Available The paper endeavors to offer an overview of the major theories on leadership and the way in which it influences the management of contemporary organizations. Numerous scholars highlight that there are numerous overlaps between the concepts of management and leadership. This is the reason why the first section of the paper focuses on providing an extensive overview of the literature regarding the meaning of the two aforementioned concepts. The second section addresses more in depth the concept of leadership and managerial leadership and focuses on the ideal profile of the leader. The last section of the paper critically discusses various types of leadership and more specifically modern approaches to the concept and practices of leadership.

  16. How I approach trabeculectomy surgery

    Directory of Open Access Journals (Sweden)

    Ian Murdoch

    2006-09-01

    Full Text Available The purpose of this article is to describe an approach to the most commonly performed surgical treatment for open-angle glaucoma, trabeculectomy. It is important to recognise that the concept of trabeculectomy surgery can be difficult for patients to comprehend in the first place. Their disease is frequently ‘thrust upon them’ by doctors; in other words, they are frequently asymptomatic in the eye that the ophthalmologist is most concerned about. The therapy, at best, can only hope to maintain vision. Vision may well deteriorate as a result of the therapy. These concepts are vital in the consideration of any surgical intervention. Preventive therapy is always more difficult to introduce. This also means the surgeon is all the more challenged to produce the safest possible result. A well-rested surgeon and a calm surgical environment is the start, along with a confident surgical technique.

  17. Validation of Modeling Flow Approaching Navigation Locks

    Science.gov (United States)

    2013-08-01

    instrumentation, direction vernier . ........................................................................ 8  Figure 11. Plan A lock approach, upstream approach...13-9 8 Figure 9. Tools and instrumentation, bracket attached to rail. Figure 10. Tools and instrumentation, direction vernier . Numerical model

  18. An Electronic Approach to Materials Design

    Institute of Scientific and Technical Information of China (English)

    Masahiko MORINAGA; Yoshinori MURATA; Hiroshi YUKAWA

    2003-01-01

    A molecular orbital approach to materials design has recently made great progress. This approach is based on the electronic structure calculations by the DV-Xα cluster method. In this paper recent progress in this approachis reviewed. In particular

  19. The inaction approach to gauge theories

    CERN Document Server

    Pivovarov, Grigorii

    2012-01-01

    The inaction approach introduced previously for phi^4 is generalized to gauge theories. It combines the advantages of the effective field theory and causal approaches to quantum fields. Also, it suggests ways to generalizing gauge theories.

  20. A Brief Overview of Communicative Approach

    Institute of Scientific and Technical Information of China (English)

    任永东

    2013-01-01

    Communicative Approach has become a popular teaching strategy.This essay mainly reviews and introduces the development and the features of Communicative Approach in order to apply this teaching methodology in English teaching for students’better learning results.

  1. A New Approach for Calculating Vacuum Susceptibility

    Institute of Scientific and Technical Information of China (English)

    宗红石; 平加伦; 顾建中

    2004-01-01

    Based on the Dyson-Schwinger approach, we propose a new method for calculating vacuum susceptibilities. As an example, the vector vacuum susceptibility is calculated. A comparison with the results of the previous approaches is presented.

  2. Symbolic Tensor Calculus -- Functional and Dynamic Approach

    CERN Document Server

    Woszczyna, A; Czaja, W; Golda, Z A

    2016-01-01

    In this paper, we briefly discuss the dynamic and functional approach to computer symbolic tensor analysis. The ccgrg package for Wolfram Language/Mathematica is used to illustrate this approach. Some examples of applications are attached.

  3. My Approaches to Promote Teaching Efficiency

    Institute of Scientific and Technical Information of China (English)

    李娟维

    2014-01-01

    Promoting teaching efficiency is a matter of the utmost concern of all teachers. This paper focuses on the different approaches that the author adopts in her teaching. These approaches include creating learning situations,using humor in teaching.

  4. Spinal trauma. An imaging approach

    Energy Technology Data Exchange (ETDEWEB)

    Cassar-Pullicino, V.N. [The Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, Shropshire (United Kingdom). Dept. of Radiology; Imhof, H. [University and General Hospital Vienna (Austria). Dept. of Radiodiagnostics

    2006-07-01

    The diagnosis of trauma to the spine - where the slightest oversight may have catastrophic results - requires a thorough grasp of the spectrum of resultant pathology as well as the imaging modalities used in making an accurate diagnosis. In Spinal Trauma, the internationally renowned team of experts provides a comprehensive, cutting-edge exposition of the current vital role of imaging in the diagnosis and treatment of injuries to the axial skeleton. Beginning with a valuable clinical perspective of spinal trauma, the book offers the reader a unique overview of the biomechanics underlying the pathology of cervical trauma. Acute trauma topics include: - Optimization of imaging modalities - Malalignment - signs and significance - Vertebral fractures - detection and implications - Classification of thoraco-lumbar fractures - rationale and relevance - Neurovascular injury. Distilling decades of clinical and teaching expertise, the contributors further discuss the current role of imaging in special focus topics, which include: - The pediatric spine - Sports injuries - The rigid spine - Trauma in the elderly - Vertebral collapse, benign and malignant - Spinal trauma therapy - Vertebral fractures and osteoporosis - Neuropathic spine. All throughout the book, the focus is on understanding the injury, and its implications and complications, through 'an imaging approach'. Lavishly illustrated with hundreds of superb MR images and CT scans, and clear full-color drawings, the authors conclude with a look into the future, defining clinical trends and research directions. Spinal Trauma - with its broad scope, practical imaging approach, and current focus - is designed to enhance confidence and accuracy, making it essential reading for clinicians and radiologists at all levels. (orig.)

  5. Computational Approaches to Vestibular Research

    Science.gov (United States)

    Ross, Muriel D.; Wade, Charles E. (Technical Monitor)

    1994-01-01

    The Biocomputation Center at NASA Ames Research Center is dedicated to a union between computational, experimental and theoretical approaches to the study of neuroscience and of life sciences in general. The current emphasis is on computer reconstruction and visualization of vestibular macular architecture in three-dimensions (3-D), and on mathematical modeling and computer simulation of neural activity in the functioning system. Our methods are being used to interpret the influence of spaceflight on mammalian vestibular maculas in a model system, that of the adult Sprague-Dawley rat. More than twenty 3-D reconstructions of type I and type II hair cells and their afferents have been completed by digitization of contours traced from serial sections photographed in a transmission electron microscope. This labor-intensive method has now been replace d by a semiautomated method developed in the Biocomputation Center in which conventional photography is eliminated. All viewing, storage and manipulation of original data is done using Silicon Graphics workstations. Recent improvements to the software include a new mesh generation method for connecting contours. This method will permit the investigator to describe any surface, regardless of complexity, including highly branched structures such as are routinely found in neurons. This same mesh can be used for 3-D, finite volume simulation of synapse activation and voltage spread on neuronal surfaces visualized via the reconstruction process. These simulations help the investigator interpret the relationship between neuroarchitecture and physiology, and are of assistance in determining which experiments will best test theoretical interpretations. Data are also used to develop abstract, 3-D models that dynamically display neuronal activity ongoing in the system. Finally, the same data can be used to visualize the neural tissue in a virtual environment. Our exhibit will depict capabilities of our computational approaches and

  6. Comprehensive approach to sarcopenia treatment.

    Science.gov (United States)

    Wakabayashi, Hidetaka; Sakuma, Kunihiro

    2014-05-01

    Sarcopenia is characterized by progressive and generalized loss of skeletal muscle mass and strength with a risk of adverse outcomes such as physical disability, poor quality of life, and death. Primary sarcopenia is considered to be age-related when no other cause is evident, other than ageing itself. Secondary sarcopenia should be considered when one or more other causes are evident, such as activity-, disease-, or nutrition-related sarcopenia. In this narrative review that focused on human studies, we summarize the pharmaceutical therapies (testosterone, dehydroepiandrosterone, estrogen, growth hormone, ghrelin, vitamin D, angiotensin converting enzyme inhibitor, and eicosapentaenoic acid) and nonpharmaceutical therapies (resistance training, protein and amino acid supplementation, and non-smoking) for counteracting primary sarcopenia. Testosterone and growth hormone improve muscle mass and muscle strength, but have several side effects. Although there are some intriguing pharmaceutical therapies to combat sarcopenia, resistance training combined with supplements containing amino acids are the most effective for preventing and treating age-related muscle wasting and weakness. The etiology of sarcopenia in the elderly is multi-factorial. Patients with disuse syndrome and deconditioning often complicate the diagnosis, of not only activity-related sarcopenia, but also age-, disease-, and nutrition-related sarcopenia. In these cases a comprehensive approach to sarcopenia treatment should include pharmaceutical therapies for age-related sarcopenia and comorbid chronic diseases, resistance training, early ambulation, nutrition management, protein and amino acid supplementation, and non-smoking. The effect of pharmaceutical therapies for sarcopenia can be enhanced by this comprehensive approach. Future research on pharmaceutical therapies for counteracting sarcopenia should consider non-pharmaceutical therapies and also the causes of sarcopenia.

  7. A systematic approach to an organization's sustainability.

    Science.gov (United States)

    Schalock, Robert L; Verdugo, Miguel; Lee, Tim

    2016-06-01

    This article integrates the concepts of sustainability and quality improvement into a systematic approach to an organization's sustainability. The article: (a) presents a literature-based model that incorporates the factors that drive an organization's sustainability; (b) describes how sustainability is operationalized through a systematic approach to quality improvement; (c) discusses the advantages of a systematic approach to sustainability; and (d) shares with the reader literature and experientially-based lessons learned about the approach.

  8. A systems approach to traditional oriental medicine

    DEFF Research Database (Denmark)

    Kim, Hyun Uk; Ryu, Jae Yong; Lee, Jong Ok;

    2015-01-01

    Analyzing structural similarities between compounds derived from traditional oriental medicine and human metabolites is a systems-based approach that can help identify mechanisms of action and suggest approaches to reduce toxicity.......Analyzing structural similarities between compounds derived from traditional oriental medicine and human metabolites is a systems-based approach that can help identify mechanisms of action and suggest approaches to reduce toxicity....

  9. Exploring Academics' Approaches to Managing Team Assessment

    Science.gov (United States)

    Augar, Naomi; Woodley, Carolyn J.; Whitefield, Despina; Winchester, Maxwell

    2016-01-01

    Purpose: The purpose of this paper is to develop an understanding of academics' approaches to managing team assessment at an Australian University with a view to informing policy development and assessment design. Design/methodology/approach: The research was conducted using a single exploratory case study approach focussing on the team assessment…

  10. A Nonviolent Approach to Social Justice Education

    Science.gov (United States)

    Wang, Hongyu

    2013-01-01

    This article advocates a nonviolent approach to social justice education. First, social justice education literature is reviewed, and two contrasting and influential approaches--critical theory and poststructural theory--are the focus of critical analysis. A nonviolent approach is proposed as an alternative. Second, the notion of social justice is…

  11. About Radiation Reaction with Force Approach

    CERN Document Server

    Velazquez, Gustavo Lopez

    2015-01-01

    The difficulty of usual approach to radiation reaction is pointed out , and a possible approach based on the force acting to the charged particle which produces the acceleration itself, is presented. This approach brings about an expression such that acceleration is zero whenever the external force is zero.

  12. Nonlinear approaches in engineering applications 2

    CERN Document Server

    Jazar, Reza N

    2013-01-01

    Provides updated principles and applications of the nonlinear approaches in solving engineering and physics problems Demonstrates how nonlinear approaches may open avenues to better, safer, cheaper systems with less energy consumption Has a strong emphasis on the application, physical meaning, and methodologies of nonlinear approaches in different engineering and science problems

  13. Materiality in a Practice-Based Approach

    Science.gov (United States)

    Svabo, Connie

    2009-01-01

    Purpose: The paper aims to provide an overview of the vocabulary for materiality which is used by practice-based approaches to organizational knowing. Design/methodology/approach: The overview is theoretically generated and is based on the anthology Knowing in Organizations: A Practice-based Approach edited by Nicolini, Gherardi and Yanow. The…

  14. Pilot Task Demand Load During RNAV Approaches

    NARCIS (Netherlands)

    Heiligers, M.M.

    2011-01-01

    The question that started this research was: “Why is approach A more difficult to fly for a pilot than approach B?”. To find an answer to this question, pilots flew a large variety of Area Navigation (RNAV) approaches during several flight simulator and real flight experiments. The results of these

  15. An Approach for Improved Planning in Colleges.

    Science.gov (United States)

    Schroeder, Roger G.

    Planning and management systems for colleges should be tailor-made to fit each particular college. The approach suggested here is flexible so that it can be adapted to individual circumstances in a variety of colleges. What is being suggested is an approach to planning rather than a technique. The approach results in two types of output documents:…

  16. Statistical sampling approaches for soil monitoring

    NARCIS (Netherlands)

    Brus, D.J.

    2014-01-01

    This paper describes three statistical sampling approaches for regional soil monitoring, a design-based, a model-based and a hybrid approach. In the model-based approach a space-time model is exploited to predict global statistical parameters of interest such as the space-time mean. In the hybrid ap

  17. Anterior approach v. posterior approach - ultrasound-guided shoulder arthrogram injection

    Directory of Open Access Journals (Sweden)

    Merle Neethling-du Toit

    2008-11-01

    Full Text Available Anterior approach ultrasound guided arthrogram injections are a quick reliable way of injecting contrast prior to MRI scan. We did a retrospective study on patients, previously injected and scanned at our clinic, to compare the more manifested posterior approach with the anterior approach. The success rate for successful intra-articular injections for the anterior approach far outweighs the posterior approach. Also the anterior approach is more tolerable for patients as the injections are much quicker and seemingly less painful. In our knowledge it is thus far better to perform anterior approach shoulder arthrogram injections than posterior approach injections

  18. Form-based Approaches vs. Task-Based Approaches

    Directory of Open Access Journals (Sweden)

    Zahra Talebi

    2015-07-01

    Full Text Available This study aimed at investigating whether task-based approaches bear any superiority to that of more traditional ones evident in presentation-practice- and production phase .to fulfill the purpose of the study, the participants within the age range of 11-19, took part in the study. Following a pretest, treatment, and a posttest, the obtained data was analyzed using analysis of covariance (ANCOVA to examine the effects of the variables. The results of the analysis showed that participants in the PPP group did significantly better in the grammar recognition of the posttest than that of the task group. However, their counterparts in the task group gained better scores in the writing section of the test .this research study provided evidence in support of task proponents' claim in the merit of task-based activity in raising learners' implicit knowledge claiming to play the primary role in spontaneous speech.Keywords: Task-based language teaching, PPP model, focus on form, focus on meaning

  19. Apprehending ganglioside diversity: a comprehensive methodological approach[S

    Science.gov (United States)

    Masson, Elodie A. Y.; Sibille, Estelle; Martine, Lucy; Chaux-Picquet, Fanny; Bretillon, Lionel; Berdeaux, Olivier

    2015-01-01

    Gangliosides (GGs) make a wide family of glycosphingolipids ubiquitously expressed in mammalian tissues and particularly abundant in the brain and nervous system. They exhibit a huge diversity due to structural variations in both their oligosaccharidic chain and ceramide moiety, which represent a real analytical challenge. Since their discovery in the 1940s, methods have persistently improved until the emergence of LC/MS, which offers a high level of specificity and sensitivity and is suitable with high-throughput profiling studies. We describe here a comprehensive approach relying on various techniques and aiming at fully characterizing GGs in biological samples. First, total GG content was determined by a biochemical assay. Second, GG class composition was assessed by high-performance thin-layer chromatography followed by colorimetric revelation. Then, ceramide types of GG classes were identified, and their relative quantification was performed thanks to the development of a powerful and reliable LC/MS method. Finally, ceramides were structurally characterized, and minor and less common GG classes were identified using high-resolution MS. These methods were applied to the rat retina to provide an exhaustive description of its GG composition, giving the base for a better understanding of the precise roles of GGs in this tissue. PMID:26142958

  20. A Novel Approach for Solving Semidefinite Programs

    Directory of Open Access Journals (Sweden)

    Hong-Wei Jiao

    2014-01-01

    Full Text Available A novel linearizing alternating direction augmented Lagrangian approach is proposed for effectively solving semidefinite programs (SDP. For every iteration, by fixing the other variables, the proposed approach alternatively optimizes the dual variables and the dual slack variables; then the primal variables, that is, Lagrange multipliers, are updated. In addition, the proposed approach renews all the variables in closed forms without solving any system of linear equations. Global convergence of the proposed approach is proved under mild conditions, and two numerical problems are given to demonstrate the effectiveness of the presented approach.

  1. Study of wafer pre-aligning approaches

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Wafer pre-aligning system is an important component in IC manufacturing industry. A wafer prealigning platform with a CCD sensor is presented in this paper. The centering and notch detecting approaches are extended based on this platform. Least square circle fitting approach is adopted to calculate the center and radius of the wafer, and a formula for calculating the fitting error is derived. An approach called edge variation rate is also proposed to detect the range of wafer notch, and the fiducial is calculated by curve fitting approach. These approaches can improve the accuracy effectively as indicated by experiments.

  2. Some approaches to polaron theory

    Science.gov (United States)

    Bogolubov, N. N.; Bogolubov, N. N.

    1985-11-01

    Here, in our approximation of polaron theory, we examine the importance of introducing the T product, which turn out to be a very convenient theoretical approach for the calculation of thermodynamical averages. We focus attention on the investigation of the so-called linear polaron Hamiltonian and present in detail the calculation of the correlation function, spectral function, and Green function for such a linear system. It is shown that the linear polaron Hamiltonian provides an exactly solvable model of our system, and the result obtained with this approach holds true for an arbitrary coupling constant which describes the strength of interaction between the electron and the lattice vibrations. Then, with the help of a variational technique, we show the possibility of reducing the real polaron Hamiltonian to a socalled trial or approximate linear model Hamiltonian. We also consider the exact calculation of free energy with a special technique that reduces calculations with the help of the T product, which, in our opinion, works much better and is easier than other analogous considerations, for example, the path-integral or Feynman-integral method.(1,2) Here we furthermore recall our own work,(4) where it was shown that the results of Refs. 7 and 8 concerning the impedance calculation in the polaron model may be obtained directly without the use of the path-integral method. The study of the polaron system's thermodynamics is carried out by us in the framework of the functional method. A calculation of the free energy and the momentum distribution function is proposed. Note also that the polaron systems with strong coupling(9) proved to be useful in different quantum field models in connection with the construction of dynamical models of composite particles. A rigorous solution of the special strong-coupling polaron problem, describing the interaction of a nonrelativistic particle with a quantum field, was given by Bogolubov.(3) The works of Tavkhelidze, Fedyanin

  3. Molecular approaches in experimental neuroimaging

    Energy Technology Data Exchange (ETDEWEB)

    Tavitian, B. [CEA Saclay, 91 - Gif sur Yvette (France)

    2009-07-01

    We quantified and compared six parameters (resolution, depth, sensitivity, portability, quantification and cost) of four molecular imaging techniques (MRI, optics, ultrasound and TEP), with the three types of electromagnetic radiation used in vivo (Frequencies (10{sup 6} to 10{sup 22} Hz), Photonic Energy (10{sup -4} to 10{sup 9} eV) and Wavelengths (10{sup -2} to 10{sup -15} m)). This form of molecular imaging demands the most sensitive technique available (Pl. 26-2 to 26-4). Four examples of experimental in vivo approaches on small animals are shown: molecular passage through the blood-brain barrier (endothelial cells, astrocytes and occludin, pharmacokinetics, studied with PET) (Pl. 2-5 to 2-11); imaging of receptors and ligands, especially peripheral benzodiazepine receptors (PBR) by PET and MRI in the rat (Pl. 2-12 to Pl. 2-15); neuro-pathology of neuro-degenerative and inflammatory diseases and stroke by PET and MRI in the rat (Pl. 2-16 to 2-17); and the study of responses to stimulation explored with in vivo imaging of calcium signals and their variations by photonic analysis, as on the scale of mitochondrial calcium (Pl.2-18 to Pl.2-22). (author)

  4. Algorithmic approach to quantum physics

    CERN Document Server

    Ozhigov, Y

    2004-01-01

    Algorithmic approach is based on the assumption that any quantum evolution of many particle system can be simulated on a classical computer with the polynomial time and memory cost. Algorithms play the central role here but not the analysis, and a simulation gives a "film" which visualizes many particle quantum dynamics and is demonstrated to a user of the model. Restrictions following from the algorithm theory are considered on a level of fundamental physical laws. Born rule for the calculation of quantum probability as well as the decoherence is derived from the existence of a nonzero minimal value of amplitude module - a grain of amplitude. The limitation on the classical computational resources gives the unified description of quantum dynamics that is not divided to the unitary dynamics and measurements and does not depend on the existence of observer. It is proposed the description of states based on the nesting of particles in each other that permits to account the effects of all levels in the same mode...

  5. New Approaches to Social Economy

    Directory of Open Access Journals (Sweden)

    Daniela VÎRJAN

    2012-06-01

    Full Text Available Social economy is a relatively new phenomenon, having started just a few decades ago, and due to this reason it has yet to reach great scale. Due to the phenomenon of global crisis propagation, the economies of all countries have been affected and have gone into an economical cycle recession phase, some economical agents hitting the climax of the crisis, practically shutting down their activities. Starting from this, some social problems started to accentuate: the number of unemployed people has risen, the poverty rate went up, the marginalization and social exclusion rates went up, the aging of the population has increased, the discrepancy between the rich and poor has widened and so on, and in this context social economy has gained a greater importance not only at an European level but also at an international level. As such, social economy may become one of the innovative and creative solutions which can contribute to a more human approach to economical problems, combining freedom of market with social responsibility to the benefit of the whole community.

  6. [Current Approaches in Cancer Immunotherapy].

    Science.gov (United States)

    Otáhal, P; Trněný, M

    2015-01-01

    Methods of cancer immunotherapy have finally entered clinical medicine after years of preclinical research. Currently, there are several methods, which have proven to be very effective even in cases of incurable cancer. Antitumor monoclonal antibodies are among major therapeutic anti-cancer drugs and have been successfully used for many ears. Novel group of antibodies are immunomodulatory antibodies which can break tumor -specific immune tolerance and induce regression of tumors by nonspecific activation of immune system. Bispecific antibodies represent a novel class of anticancer agents which can induce expansion of T cells in vivo, blinatumomab is an example of such agents and is currently available for the treatment of acute B -cell leukemia. Cellular immunotherapy is also very effective, especially the use of Chimeric receptor modified T-cells for the therapy of B- cell lymphoproliferative diseases. Although it is a very complicated and expensive method, it is highly effective approach which can induce remission even in previously hopeless conditions. The goal of this article is to explain the basic principles of cancer immunotherapy and summarize the newest findings in this field.

  7. Approaches to Modeling of Recrystallization

    Directory of Open Access Journals (Sweden)

    Håkan Hallberg

    2011-10-01

    Full Text Available Control of the material microstructure in terms of the grain size is a key component in tailoring material properties of metals and alloys and in creating functionally graded materials. To exert this control, reliable and efficient modeling and simulation of the recrystallization process whereby the grain size evolves is vital. The present contribution is a review paper, summarizing the current status of various approaches to modeling grain refinement due to recrystallization. The underlying mechanisms of recrystallization are briefly recollected and different simulation methods are discussed. Analytical and empirical models, continuum mechanical models and discrete methods as well as phase field, vertex and level set models of recrystallization will be considered. Such numerical methods have been reviewed previously, but with the present focus on recrystallization modeling and with a rapidly increasing amount of related publications, an updated review is called for. Advantages and disadvantages of the different methods are discussed in terms of applicability, underlying assumptions, physical relevance, implementation issues and computational efficiency.

  8. New approaches to treating pain.

    Science.gov (United States)

    Wolkerstorfer, Andrea; Handler, Norbert; Buschmann, Helmut

    2016-02-15

    Pain is the most common reason for patients seeking medical care resulting in an estimated world market for analgesics of more than USD 50 billion. Pain is a highly complex, heterogeneous and dynamic process characterized by specific patterns of phenotypic sensory neuronal change. Current treatment options for pain include opioids and non-opioid analgesics, acetaminophen and non-steroidal anti-inflammatory drugs and other drug classes such as antidepressants and anticonvulsants and a combination thereof. Novel approaches are focusing on the optimization of side-effect profiles of opioid based analgesics, the improvement of selectivity for specific opioid receptors, or by addressing molecular gateways implicated in pain. Promising candidates in development target various types of voltage-gated ion channels and receptors for capsaicin and analogs. Currently, after decades of pain research it has to be stated that the assessment, prevention and treatment of pain in industrialized countries as well as in low-income and middle-income countries are neither adequate nor equitable. Further research is needed so that specifically chronic pain control can be improved and individualized.

  9. Mindful approach to University education

    Directory of Open Access Journals (Sweden)

    Broggi F

    2016-09-01

    Full Text Available Fiorenza Broggi,1 Monica Bomba,1 Michela Rimondini,2 Maura Mutti,1 Sara Pasta,1 Chiara Ricci,1 Luca Tagliabue,1 Silvia Valsecchi,1 Elide Monaco,1 Francesca Neri,1 Silvia Oggiano,2 Renata Nacinovich,1 1Department of Child and Adolescent Psychiatry, San Gerardo Hospital, University of Milano–Bicocca, Monza, 2Department of Clinical Psychology, University of Verona, Italy Abstract: A mindful approach to education and training could improve students’ reflective capacities and have positive effects on clinical practice because it facilitates a helping relationship. The main aims of this study were to investigate whether participation in a mindful-based University training was associated with increases in mindfulness skills as measured by the 5-Facet M Questionnaire, and to present the Italian validation of the questionnaire. Sixty-seven students from the course Neuro and Psychomotor Therapy were enrolled. They filled in the self-administered 5-Facet M Questionnaire before and 1 month after a mindfulness-based training, focused on role-playing and followed by a feedback group discussion. The Italian version of the 5-Facet M Questionnaire had good psychometric properties. The pre- and post-training analysis showed a significant increase in the subscale ‘Observing’. Findings suggest that role-playing and feedback group sessions are valid tools to improve students’ mindfulness skills. Keywords: mindfulness, role play, self-awareness, communication skills, insight, reflective capacities, feedback

  10. Hyperprolactinemia: pathophysiology and therapeutic approach.

    Science.gov (United States)

    Capozzi, Anna; Scambia, Giovanni; Pontecorvi, Alfredo; Lello, Stefano

    2015-07-01

    Prolactin (PRL) is a hormone, mainly secreted by lactotroph cells of the anterior pituitary gland. Recent studies have shown it may also be produced by many extrapituitary cells. Its well-recognized PRL plays an important role in lactation during pregnancy, but it is involved in other biological functions such as angiogenesis, immunoregulation and osmoregulation. Hyperprolactinemia is a typical condition producing reproductive dysfunction in both sexes, resulting in hypogonadism, infertility and galactorrhea. It may be also asymptomatic. Lactotroph adenomas (prolactinoma) is one of the most common cause of PRL excess, representing approximately 40% of all pituitary tumors. Several other conditions should be excluded before a clear diagnosis of hyperprolactinemia is made. Hyperprolactinemia may be secondary to pharmacological or pathological interruption of hypothalamic-pituitary dopaminergic pathways or idiopathic. Stress, renal failure or hypothyroidism are other frequent conditions to exclude in patients with hyperprolactinemia. We will review biochemical characteristics and physiological functions of that hormone. Clinical and pharmacological approach to hyperprolactinemia will also be discussed.

  11. Deficient Approaches to Human Neuroimaging

    Directory of Open Access Journals (Sweden)

    Johannes eStelzer

    2014-07-01

    Full Text Available Functional magnetic resonance imaging (fMRI is the workhorse of imaging-based human cognitive neuroscience. The use of fMRI is ever-increasing; within the last 4 years more fMRI studies have been published than in the previous 17 years. This large body of research has mainly focused on the functional localization of condition- or stimulus-dependent changes in the blood-oxygenation-level dependent (BOLD signal.In recent years, however, many aspects of the commonly practiced analysis frameworks and methodologies have been critically reassessed. Here we summarize these critiques, providing an overview of the major conceptual and practical deficiencies in widely used brain-mapping approaches, and exemplify some of these issues by the use of imaging data and simulations. In particular, we discuss the inherent pitfalls and shortcomings of methodologies for statistical parametric mapping. Our critique emphasizes recent reports of excessively high numbers of both false positive and false negative findings in fMRI brain mapping. We outline our view regarding the broader scientific implications of these methodological considerations and briefly discuss possible solutions.

  12. Angioedema: Diagnosis and treatment approaches

    Directory of Open Access Journals (Sweden)

    Ali Tahsin Güneş

    2013-03-01

    Full Text Available Angioedema (AE is defined as sudden, localized and transient swelling of the skin and/or mucous membranes. This swelling condition is a result of interstitial edema from vasoactive mediators increasing the permeability of postcapillary venules of the subcutaneous and submucosal tissues. When localized to the skin, it presents as asymmetric, nonpitting, nondependent, and occasionally painful edema. However, mucosal attacks, such as laryngeal edema and bowel involvement can produce severe discomfort and life-threatening symptoms. There are several forms including those involving dysfunction or depletion of the C1-inhibitor gene (classical hereditary AE types and acquired AE, allergic AE, drug-induced AE (nonsteroidal anti-inflammatory drug-induced AE, angiotensin converting enzyme inhibitor-induced AE, idiopathic and a recently described form, HAE type 3. These various forms of AE have overlapping symptoms, but some unique clinical and historical features as well as presence of accompanying urticaria can aid in the differential diagnosis. The key to successful management is to rule out conditions that masquerade as AE, detection and avoidance of triggers, early recognition of attacks, and aggressive airway management when warranted. In this article, common and rare forms as well as clinical symptoms, differential diagnosis, and treatment approaches for AE are reviewed.

  13. The Wonder Approach to learning.

    Science.gov (United States)

    L'Ecuyer, Catherine

    2014-01-01

    Wonder, innate in the child, is an inner desire to learn that awaits reality in order to be awakened. Wonder is at the origin of reality-based consciousness, thus of learning. The scope of wonder, which occurs at a metaphysical level, is greater than that of curiosity. Unfortunate misinterpretations of neuroscience have led to false brain-based ideas in the field of education, all of these based on the scientifically wrong assumption that children's learning depends on an enriched environment. These beliefs have re-enforced the Behaviorist Approach to education and to parenting and have contributed to deadening our children's sense of wonder. We suggest wonder as the center of all motivation and action in the child. Wonder is what makes life genuinely personal. Beauty is what triggers wonder. Wonder attunes to beauty through sensitivity and is unfolded by secure attachment. When wonder, beauty, sensitivity and secure attachment are present, learning is meaningful. On the contrary, when there is no volitional dimension involved (no wonder), no end or meaning (no beauty) and no trusting predisposition (secure attachment), the rigid and limiting mechanical process of so-called learning through mere repetition become a deadening and alienating routine. This could be described as training, not as learning, because it does not contemplate the human being as a whole.

  14. Stepwise approach for view synthesis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents some techniques for synthesizing novel view for a virtual viewpoint from two given views captured at different viewpoints to achieve both high quality and high efficiency. The whole process consists of three passes. The first pass recovers depth map. We formulate it as pixel labelling and propose a bisection approach to solve it. It is accomplished in log2n (n is the number of depth levels) steps, each of which involves a single graph cut computation. The second pass detects occluded pixels and reasons about their depth. It fits a foreground depth curve and a background depth curve using depth of nearby foreground and background pixels, and then distinguishes foreground and background pixels by minimizing a global energy, which involves only one graph cut computation. The third pass finds for each pixel in the novel view the corresponding pixels in the input views and computes its color. The whole process involves only a small number of graph cut computations, therefore it is efficient.And, visual artifacts in the synthesized view can be removed successfully by correcting depth of the occluded pixels. Experimental results demonstrate that both high quality and high efficiency are achieved by the proposed techniques.

  15. NASA's Approach to Software Assurance

    Science.gov (United States)

    Wetherholt, Martha

    2015-01-01

    NASA defines software assurance as: the planned and systematic set of activities that ensure conformance of software life cycle processes and products to requirements, standards, and procedures via quality, safety, reliability, and independent verification and validation. NASA's implementation of this approach to the quality, safety, reliability, security and verification and validation of software is brought together in one discipline, software assurance. Organizationally, NASA has software assurance at each NASA center, a Software Assurance Manager at NASA Headquarters, a Software Assurance Technical Fellow (currently the same person as the SA Manager), and an Independent Verification and Validation Organization with its own facility. An umbrella risk mitigation strategy for safety and mission success assurance of NASA's software, software assurance covers a wide area and is better structured to address the dynamic changes in how software is developed, used, and managed, as well as it's increasingly complex functionality. Being flexible, risk based, and prepared for challenges in software at NASA is essential, especially as much of our software is unique for each mission.

  16. Understanding Progress: A Heterodox Approach

    Directory of Open Access Journals (Sweden)

    Blanca Lemus

    2013-01-01

    Full Text Available This paper examines the possibility of understanding and measuring well-being as a result of “progress” on the basis of today’s dominant epistemological framework. Market criteria distort social values by allowing purchasing power to define priorities, likening luxury goods to basic needs; in the process they reinforce patterns of discrimination against disadvantaged social groups and women, introducing fatal distortions into the analysis. Similarly, because there are no appropriate mechanisms to price natural resources adequately, the market overlooks the consequences of the abuse of natural resources, degrading the quality of life, individually and collectively, or—in the framework of Latin American indigenous groups—foreclosing the possibility of “living well”. We critique the common vision of the official development discourse that places its faith on technological innovations to resolve these problems. The analysis points to the need for new models of social and environmental governance to promote progress, approaches like those suggested in the paper that are inconsistent with public policies currently in place. At present, the social groups forging institutions to assure their own well-being and ecological balance are involved in local processes, often in opposition to the proposals of the political leaders in their countries.

  17. Therapeutic approach to epileptic encephalopathies.

    Science.gov (United States)

    Vigevano, Federico; Arzimanoglou, Alexis; Plouin, Perrine; Specchio, Nicola

    2013-11-01

    Epileptic encephalopathies (EEs) are electroclinical entities with a peculiar course of disease; seizures and electroencephalographic (EEG) epileptiform abnormalities, ictal and interictal, contribute to progressive disturbance of cerebral functions. Frequently EEs are drug resistant, and consequences may be catastrophic. The main goal of treatment is to stop the peculiar course of epilepsy, operating on three parameters: seizure control, reduction of EEG abnormalities, and developmental outcome. For a correct therapeutic approach it is mandatory to have an as accurate as possible syndromic and etiologic diagnosis. Given the poor efficacy of conventional antiepileptic drugs (AEDs), the use of specific drugs for EEs, such as adrenocorticotropic hormone (ACTH) and corticosteroids or stiripentol is suggested. In some cases the choice of treatment is strictly related to the etiology: vigabatrin in tuberous sclerosis, ketogenic diet in glucose transporter type 1 (GLUT-1) deficiency, and pyridoxine in pyridoxine deficiency. Some AEDs combinations, such as sodium valproate with lamotrigine, have also provided interesting results, for example, in Lennox-Gastaut syndrome, although controlled studies are lacking. Finally, early surgery can be an option in children with focal structural abnormalities responsible for EEs preferably before irreversible damage on developmental outcome. Multispecialist support is recommended in EE. Management should be global from the onset, integrating not only seizure control but also all issues related to comorbidities, particularly neuropsychological and psychiatric.

  18. Comprehensive approach to diabetic nephropathy

    Directory of Open Access Journals (Sweden)

    Bancha Satirapoj

    2014-09-01

    Full Text Available Diabetic nephropathy (DN is a leading cause of mortality and morbidity in patients with diabetes. This complication reflects a complex pathophysiology, whereby various genetic and environmental factors determine susceptibility and progression to end-stage renal disease. DN should be considered in patients with type 1 diabetes for at least 10 years who have microalbuminuria and diabetic retinopathy, as well as in patients with type 1 or type 2 diabetes with macroalbuminuria in whom other causes for proteinuria are absent. DN may also present as a falling estimated glomerular filtration rate with albuminuria as a minor presenting feature, especially in patients taking renin–angiotensin–aldosterone system inhibitors (RAASi. The pathological characteristic features of disease are three major lesions: diffuse mesangial expansion, diffuse thickened glomerular basement membrane, and hyalinosis of arterioles. Functionally, however, the pathophysiology is reflected in dysfunction of the mesangium, the glomerular capillary wall, the tubulointerstitium, and the vasculature. For all diabetic patients, a comprehensive approach to management including glycemic and hypertensive control with RAASi combined with lipid control, dietary salt restriction, lowering of protein intake, increased physical activity, weight reduction, and smoking cessation can reduce the rate of progression of nephropathy and minimize the risk for cardiovascular events. This review focuses on the latest published data dealing with the mechanisms, diagnosis, and current treatment of DN.

  19. Reverse Genetic Approaches in Zebrafish

    Institute of Scientific and Technical Information of China (English)

    Peng Huang; Zuoyan Zhu; Shuo Lin; Bo Zhang

    2012-01-01

    Zebrafish (Danio rerio) is a well-established vertebrate animal model.A comprehensive collection of reverse genetics tools has been developed for studying gene function in this useful organism.Morpholino is the most widely used reagent to knock down target gene expression post-transcriptionally.For a long time,targeted genome modification has been heavily relied on large-scale traditional forward genetic screens,such as ENU (N-ethyl-N-nitrosourea) mutagenesis derived TILLING (Targeting Induced Local Lesions IN Genomes)strategy and pseudo-typed retrovirus mediated insertional mutagenesis.Recently,engineered endonucleases,including ZFNs (zinc finger nucleases) and TALENs (transcription activator-like effector nucleases),provide new and efficient strategies to directly generate sitespecific indel mutations by inducing double strand breaks in target genes.Here we summarize the major reverse genetic approaches for loss-of-function studies used and emerging in zebrafish,including strategies based on genome-wide mutagenesis and methods for sitespecific gene targeting.Future directions and expectations will also be discussed.

  20. The wonder approach to learning

    Directory of Open Access Journals (Sweden)

    Catherine eL'Ecuyer

    2014-10-01

    Full Text Available Wonder, innate in the child, is an inner desire to learn that awaits reality in order to be awakened. Wonder is at the origin of reality-based consciousness, thus of learning. The scope of wonder, which occurs at a metaphysical level, is greater than that of curiosity. Unfortunate misinterpretations of neuroscience have led to false brain-based ideas in the field of education, all of these based on the scientifically wrong assumption that children’s learning depends on an enriched environment. These beliefs have re-enforced the Behaviorist Approach to education and to parenting and have contributed to deadening our children’s sense of wonder. We suggest wonder as the center of all motivation and action in the child. Wonder is what makes life genuinely personal. Beauty is what triggers wonder. Wonder attunes to beauty through sensitivity and is unfolded by attachment. When wonder, beauty, sensitivity and secure attachment are present, learning is meaningful.On the contrary, when there is no volitional dimension involved (no wonder, no end or meaning (no beauty and no trusting predisposition (secure attachment, the rigid and limiting mechanical process of so-called learning through mere repetition become a deadening and alienating routine. This could be described as training, not as learning, because it does not contemplate the human being as a whole.

  1. Current clinical approach to achalasia

    Institute of Scientific and Technical Information of China (English)

    Alexander J Eckardt; Volker F Eckardt

    2009-01-01

    Idiopathic achalasia is a rare primary motility disorder of the esophagus.The classical features are incomplete relaxation of a frequently hypertensive lower esophageal sphincter (LES) and a lack of peristalsis in the tubular esophagus.These motor abnormalities lead to dysphagia,stasis,regurgitation,weight loss,or secondary respiratory complications.Although major strides have been made in understanding the pathogenesis of this rare disorder,including a probable autoimmune mediated destruction of inhibitory neurons in response to an unknown insult in genetically susceptible individuals,a definite trigger has not been identified.The diagnosis of achalasia is suggested by clinical features and confirmed by further diagnostic tests,such as esophagogastroduodenoscopy (EGD),manometry or barium swallow.These studies are not only used to exclude pseudoachalasia,but also might help to categorize the disease by severity or clinical subtype.Recent advances in diagnostic methods,including high resolution manometry (HRM),might allow prediction of treatment responses.The primary treatments for achieving long-term symptom relief are surgery and endoscopic methods.Although limited high-quality data exist,it appears that laparoscopic Heller myotomy with partial fundoplication is superior to endoscopic methods in achieving long-term relief of symptoms in the majority of patients.However,the current clinical approach to achalasia will depend not only on patients' characteristics and clinical subtypes of the disease,but also on local expertise and patient preferences.

  2. Our 2014 approach to mucormycosis.

    Science.gov (United States)

    Tacke, Daniela; Koehler, Philipp; Markiefka, Birgid; Cornely, Oliver A

    2014-09-01

    Mucormycosis, previously termed as zygomycosis, is caused by fungi belonging to the order Mucorales and is a very severe disease in immunocompromised patients with an often unfavourable outcome. Given the high morbidity and mortality of mucormycosis, establishing a timely diagnosis followed by immediate treatment is of major importance. As randomised clinical trials are lacking, we present our current diagnostic and treatment pathways for mucormycosis in the immunocompromised host. Due to the difficulty to distinguish mucormycosis from other filamentous fungi, mucormycosis always has to be considered as differential diagnosis in predisposed patients. Diagnostic procedures comprise imaging, microscopy, culture and histopathology and need to be rigorously used. In patients with a high suspicion of mucormycosis, e.g. reversed halo sign on computed tomography scanning, our approach combines liposomal amphotericin B (LAmB) with surgical debridement. In light of the rapid deterioration and poor prognosis of these patients, we prefer a daily dose of LAmB of at least 5 mg kg(-1) despite nephrotoxicity. In patients with stable disease we switch to posaconazole 200 mg four times per day. In case of progression antifungal combination is an option.

  3. Batch Scheduling a Fresh Approach

    Science.gov (United States)

    Cardo, Nicholas P.; Woodrow, Thomas (Technical Monitor)

    1994-01-01

    The Network Queueing System (NQS) was designed to schedule jobs based on limits within queues. As systems obtain more memory, the number of queues increased to take advantage of the added memory resource. The problem now becomes too many queues. Having a large number of queues provides users with the capability to gain an unfair advantage over other users by tailoring their job to fit in an empty queue. Additionally, the large number of queues becomes confusing to the user community. The High Speed Processors group at the Numerical Aerodynamics Simulation (NAS) Facility at NASA Ames Research Center developed a new approach to batch job scheduling. This new method reduces the number of queues required by eliminating the need for queues based on resource limits. The scheduler examines each request for necessary resources before initiating the job. Also additional user limits at the complex level were added to provide a fairness to all users. Additional tools which include user job reordering are under development to work with the new scheduler. This paper discusses the objectives, design and implementation results of this new scheduler

  4. Innovative approach towards understanding optics

    Science.gov (United States)

    Garg, Amit; Bharadwaj, Sadashiv Raj; Kumar, Raj; Shudhanshu, Avinash Kumar; Verma, Deepak Kumar

    2016-01-01

    Over the last few years, there has been a decline in the students’ interest towards Science and Optics. Use of technology in the form of various types of sensors and data acquisition systems has come as a saviour. Till date, manual routine tools and techniques are used to perform various experimental procedures in most of the science/optics laboratories in our country. The manual tools are cumbersome whereas the automated ones are costly. It does not enthuse young researchers towards the science laboratories. There is a need to develop applications which can be easily integrated, tailored at school and undergraduate level laboratories and are economical at the same time. Equipments with advanced technologies are available but they are uneconomical and have complicated working principle with a black box approach. The present work describes development of portable tools and applications which are user-friendly. This is being implemented using open-source physical computing platform based on a simple low cost microcontroller board and a development environment for writing software. The present paper reports the development of an automated spectrometer, an instrument used in almost all optics experiments at undergraduate level, and students’ response to this innovation. These tools will inspire young researchers towards science and facilitate development of advance low cost equipments making life easier for Indian as well as developing nations.

  5. Diagnostic approach to peripheral neuropathy

    Directory of Open Access Journals (Sweden)

    Misra Usha

    2008-01-01

    Full Text Available Peripheral neuropathy refers to disorders of the peripheral nervous system. They have numerous causes and diverse presentations; hence, a systematic and logical approach is needed for cost-effective diagnosis, especially of treatable neuropathies. A detailed history of symptoms, family and occupational history should be obtained. General and systemic examinations provide valuable clues. Neurological examinations investigating sensory, motor and autonomic signs help to define the topography and nature of neuropathy. Large fiber neuropathy manifests with the loss of joint position and vibration sense and sensory ataxia, whereas small fiber neuropathy manifests with the impairment of pain, temperature and autonomic functions. Electrodiagnostic (EDx tests include sensory, motor nerve conduction, F response, H reflex and needle electromyography (EMG. EDx helps in documenting the extent of sensory motor deficits, categorizing demyelinating (prolonged terminal latency, slowing of nerve conduction velocity, dispersion and conduction block and axonal (marginal slowing of nerve conduction and small compound muscle or sensory action potential and dennervation on EMG. Uniform demyelinating features are suggestive of hereditary demyelination, whereas difference between nerves and segments of the same nerve favor acquired demyelination. Finally, neuropathy is classified into mononeuropathy commonly due to entrapment or trauma; mononeuropathy multiplex commonly due to leprosy and vasculitis; and polyneuropathy due to systemic, metabolic or toxic etiology. Laboratory investigations are carried out as indicated and specialized tests such as biochemical, immunological, genetic studies, cerebrospinal fluid (CSF examination and nerve biopsy are carried out in selected patients. Approximately 20% patients with neuropathy remain undiagnosed but the prognosis is not bad in them.

  6. Standard Approaches to the Acetabulum Part 1: Kocher-Langenbeck Approach.

    Science.gov (United States)

    Gänsslen, A; Grechenig, S; Nerlich, M; Müller, M

    2016-01-01

    Historically, standard approaches for surgical treatment of displaced acetabular fractures were the KocherLangenbeck approach, the ilioinguinal approach and the extended iliofemoral approach (12). Presently, several modifications of these approaches are accepted alternatives, especially anterior modifications based on the intrapelvic approach described by Hirvensalo (8). Single access approaches allowing visualization of one acetabular column are the posterior Kocher-Langenbeck approach and the anterior ilioinguinal approach (12) and the use of a single approach is favoured (9, 24). For more complex situations, in the 80s and 90s extended approaches (extended iliofemoral approach according to Letournel (12), its modification to Reinert (19) (Baltimore approach), and the Triradiate approach according to Mears (14)) were introduced. These approaches are presently rarely choosen due to the extensive soft tissue dissection and higher complication rates (28). Alternatively, the combination of an anterior and posterior standard approach was recommended (7, 21, 22) having the disadvantage of longer operating time and blood loss and showed no superior results compared to a single approach. The meta-analysis by Giannoudis et al. stated that 48,7% of patients were treated using the Kocher-Langenbeck approach, followed by 21,9% ilioinguinal approaches and 12,4% extended approaches (6). More recent data from the years 2005-2007, showed that anterior approaches are now predominantly used according to a higher number of acetabular fractures with anterior column involvement. Overall, more than 40% of all patients with acetabular fractures are still approached via the Kocher-Langenbeck approach (18). Therefore, the Kocher-Langenbeck approach is still a "working horse" in approaching displaced acetabular fractures. The Kocher-Langenbeck approach consists of two parts. In 1874 von Langenbeck described a longitudinal incision starting from above the greater sciatic notch to the

  7. Preparation and self-assembly behavior of polystyrene-block-poly (dimethylaminoethyl methacrylate amphiphilic block copolymer using atom transfer radical polymerization

    Directory of Open Access Journals (Sweden)

    2008-03-01

    Full Text Available Asymmetric and semi-symmetric amphiphilic diblock copolymers polystyrene-block-poly (dimethylaminoethyl methacrylate (PS-b-PDMAEMA with the same PS block length of 62 repeat units and quite short (3 repeat units or equivalent (47 repeat units length of PDMAEMA have been prepared simply by varying the ratio of the bromine-terminated macroinitiator polystyrene (PS-Br to DMAEMA using atom transfer radical polymerization (ATRP. The chemical structures and compositions of the PS-b-PDMAEMA block copolymers are studied by nuclear magnetic resonance (NMR spectroscopy, gel permeation chromatography (GPC, and elementary analysis (EA. The self-assembly behaviors of copolymers in N,N-dimethyl formamide (DMF with different pH and dioxane/water binary solvent mixture by direct dissolution method (DD, are studied by transmission electron microscopy (TEM, electron diffracting analysis (EDA, and energy-dispersive analysis of X-rays (EDAX techniques. Transmission electron microscopy results suggest that asymmetric block copolymer PS62-b-PDMAEMA3 (the numbers in the form of footnotes represent repeated units of each monomer in the copolymer can form spherical core-shell micelles, large compound reverse micelles (LCRMs, hexagonal/rhombic phases, reverse hexagonal/rhombic phases, vesicles, reverse vesicles and necklace-like reverse micelles, controlled by common or selective solvent and pH, while most of the aggregates of semi-symmetric PS62-b-PDMAEMA47 are simply spherical, such as spherical core-shell micelles and reverse spherical core-shell micelles, besides hexagonal/rhombic phases. All above structures are controlled by three components of the free energy of aggregation: core-chain stretching, interfacial energy and intercoronal chain interaction.

  8. The effect of hydrophilic and hydrophobic block length on the rheology of amphiphilic diblock Polystyrene-b-Poly(sodium methacrylate) copolymers prepared by ATRP

    NARCIS (Netherlands)

    Raffa, Patrizio; Stuart, Marc C.A.; Broekhuis, Antonius A.; Picchioni, Francesco

    2014-01-01

    Following our previous investigation on the effect of molecular architecture on the rheology of Polystyrene-b-Poly(sodium methacrylate) copolymers (PS-b-PMAA), we consider here diblock PS-b-PMAA copolymers characterized by a different length of either the hydrophilic or the hydrophobic block. Variou

  9. ATR-p53 restricts homologous recombination in response to replicative stress but does not limit DNA interstrand crosslink repair in lung cancer cells.

    Directory of Open Access Journals (Sweden)

    Bianca M Sirbu

    Full Text Available Homologous recombination (HR is required for the restart of collapsed DNA replication forks and error-free repair of DNA double-strand breaks (DSB. However, unscheduled or hyperactive HR may lead to genomic instability and promote cancer development. The cellular factors that restrict HR processes in mammalian cells are only beginning to be elucidated. The tumor suppressor p53 has been implicated in the suppression of HR though it has remained unclear why p53, as the guardian of the genome, would impair an error-free repair process. Here, we show for the first time that p53 downregulates foci formation of the RAD51 recombinase in response to replicative stress in H1299 lung cancer cells in a manner that is independent of its role as a transcription factor. We find that this downregulation of HR is not only completely dependent on the binding site of p53 with replication protein A but also the ATR/ATM serine 15 phosphorylation site. Genetic analysis suggests that ATR but not ATM kinase modulates p53's function in HR. The suppression of HR by p53 can be bypassed under experimental conditions that cause DSB either directly or indirectly, in line with p53's role as a guardian of the genome. As a result, transactivation-inactive p53 does not compromise the resistance of H1299 cells to the interstrand crosslinking agent mitomycin C. Altogether, our data support a model in which p53 plays an anti-recombinogenic role in the ATR-dependent mammalian replication checkpoint but does not impair a cell's ability to use HR for the removal of DSB induced by cytotoxic agents.

  10. Approaches to adolescent pregnancy prevention.

    Science.gov (United States)

    Haffner, D; Casey, S

    1986-09-01

    The US has one of the highest teenage pregnancy rates in the industrialized world, over 1,000,000 a year. This can add to social problems including poverty, unemployment, family breakup, juvenile crime, school dropouts, and child abuse. In several studies various approaches have been developed and it is concluded that teens must not only be given the knowledge to avoid teen pregnancies, but the motivation to do so. Sex education is an important part of pregnancy prevention, but few programs go beyond the facts of reproduction and less than 14% of them are 40 hours long. Studies have shown mixed results as to the effect of education on teen pregnancy. There are many programs that have been developed by different communities, including computer programs and youth service agencies. Religious groups also play an important part in sex education and they have some distinct advantages in affecting teens' sexual values and activities. Education programs for teen's parents appear to be very important since studies show when sexuality is discussed at home, the teens begin activity later and use birth control more. Clinics have had difficulty recruiting and retaining teen patients and devote special attention to establishing a rapport with them. The school-based clinic is becoming increasingly popular and can provide birth control counseling, contraceptives, family planning clinic referral, examinations, pregnancy testing, and prenatal care. There success is due to confidentiality, convenience, and comprehensive service. However, since nearly all efforts on teen pregnancy prevention are directed at girls, 1/2 of those involved in teen pregnancies--males--are not participating in programs. This must change for longterm success of these programs and also the involvement of the community and media.

  11. Study strategies and approaches to learning

    DEFF Research Database (Denmark)

    Christensen, Hans Peter

    Process Questionnaire to identify their approach to learning. It was hypothesised that the students’ learning approach would depend more on the quality of the study work than on the quantity; that an active and reflective study strategy was required to obtain deep conceptual understanding. The result...... showed a weak correlation between the student’s main learning approach as defined by the ratio of the deep approach score to the surface approach score and the student’s study intensity as identified by the ratio of non-scheduled independent activities to scheduled teacher-controlled activities....... There was however a much stronger linear correlation (significant at the 0.01 level) between the deep-surface ratio and the total study load. The same result was observed when measuring other students’ study strategy and learning approach for a single course. The empirical basis is still too limited to draw...

  12. An intelligent approach to nanotechnology

    Science.gov (United States)

    Demming, Anna

    2013-11-01

    Control counts for little without a guiding principle. Whether manipulating atoms with a scanning probe or controlling carrier concentration in thin film deposition, intelligent intervention is required to steer the process from aimless precision towards a finely optimized design. In this issue G M Sacha and P Varona describe how artificial intelligence approaches can help towards modelling and simulating nanosystems, increasing our grasp of the nuances of these systems and how to optimize them for specific applications [1]. More than a labour-saving technique their review also suggests how genetic algorithms and artificial neural networks can supersede existing capabilities to tackle some of the challenges in moving a range of nanotechnologies forward. Research has made giant strides in determining not just what system parameters enhance performance but how. Nanoparticle synthesis is a typical example, where the field has shifted from simple synthesis and observation to unearthing insights as to dominating factors that can be identified and enlisted to control the morphological and chemical properties of synthesized products. One example is the neat study on reaction media viscosity for silver nanocrystal synthesis, where Park, Im and Park in Korea demonstrated a level of size control that had previously proved hard to achieve [2]. Silver nanoparticles have many potential applications including catalysis [3], sensing [4] and surface enhanced Raman scattering [5]. In their study, Park and colleagues obtain size-controlled 30 nm silver nanocrystals in a viscosity controlled medium of 1,5-pentanediol and demonstrate their use as sacrificial cores for the fabrication of a low-refractive filler. Another nanomaterial that has barely seen an ebb in research activity over the past two decades is ZnO, with a legion of reports detailing how to produce ZnO in different nanoscale forms from rods [6], belts [7] and flowers [8] to highly ordered arrays of vertically aligned

  13. Biotechnology Approaches to Life Detection

    Science.gov (United States)

    Steele, Andrew; McKay, David; Schweitzer, Mary

    2001-01-01

    The direct detection of organic biomarkers for living or fossil microbes on Mars by an in situ instrument is a worthy goal for future lander missions. Several new and innovative biotechnology approaches are being explored. Firstly we have proposed an instrument based on immunological reactions to specific antibodies to cause activation of fluorescent stains. Antibodies are raised or acquired to a variety of general and specific substances that might be in Mars soil. These antibodies are then combined with various fluorescent stains and applied to micron sized numbered spots on a small (2-3 cm) test plate where they become firmly attached after freeze drying. Using technology that has been developed for gene mining in DNA technology up to 10,000 tests per square inch can now be applied to a test plate. On Mars or the planet/moon of interest, a sample of soil from a trench or drill core is extracted with water and/or an organic solvent and ultrasonication and then applied to the test plate. Any substance, which has an antibody on the test plate, will react with its antibody and activate its fluorescent stain. At the moment a small UV light source will illuminate the test plate, which is observed with a small CCD camera, although other detection systems will be applied. The numbered spots that fluoresce indicate the presence of the tested-for substance, and the intensity indicates relative amounts. Furthermore with up to a thousand test plates available false positives and several variations of antibody can also be screened for. The entire instrument can be quite small and light, on the order of 10 cm in each dimension. A possible choice for light source may be small UV lasers at several wavelengths. Some of the wells or spots can contain simply standard fluorescent stains used to detect live cells, dead cells, DNA, etc. The stains in these spots may be directly activated, with no antibodies being necessary. The proposed system will look for three classes of

  14. A nonmainstream approach against cancer.

    Science.gov (United States)

    Fais, Stefano

    2016-12-01

    The discovery of antibiotics as specific and effective drugs against infectious agents has generated the belief that the famous Paul Erlich theory on magic bullet should be applied to cancer as well. However, after around 60 years of failures in finding a magic bullet against cancer, a question appears mandatory: does the magic bullet against cancer really exist? In trying to understand more on the issue, we propose three discoveries are coming from a nonmainstream approach against cancer. Tumor is acidic, and tumor acidity impairs drugs entering within tumor cells and isolates tumors from the rest of the body. Proton pumps are key in allowing tumor cells to live in the acidic microenvironment. A class of antiacidic drugs, proton pump inhibitors (PPIs), were shown to have a potent anti-tumor effect, through inhibition of proton pumps in tumor cells. PPIs are indeed prodrugs needing acidity to be activated into the active molecule. So they use protonation by H+ as an activating mechanism, while the vast majority of drugs are totally neutralized by protonation. An anti-tumor therapy based on PPI showed to be effective both in vitro and in vivo. Differently from normal cells, cancer cells meet their energy needs in great part by fermentation, and it appears conceivable that hypoxia and low nutrient transform tumor cells into fermenting anaerobes. This suggests that cancer cells are more similar to unicellular organisms, aimed at surviving in a continuous fighting, rather than cooperating, with other cells, as it occurs in the normal homeostasis of our body. We have shown that cancer cells take their fuel by "cannibalizing" other cells, either dead or alive, especially when starved and in acidic condition. This finding led to the discovery of a new oncogene TM9SF4 that human malignant cell shares with amoebas. The evidence is accumulating that almost all the cells release extracellular vehicles (EVs), from micro- to nanosize, which shuttle a variety of molecules. Tumor

  15. Physical approach to complex systems

    Science.gov (United States)

    Kwapień, Jarosław; Drożdż, Stanisław

    2012-06-01

    Typically, complex systems are natural or social systems which consist of a large number of nonlinearly interacting elements. These systems are open, they interchange information or mass with environment and constantly modify their internal structure and patterns of activity in the process of self-organization. As a result, they are flexible and easily adapt to variable external conditions. However, the most striking property of such systems is the existence of emergent phenomena which cannot be simply derived or predicted solely from the knowledge of the systems’ structure and the interactions among their individual elements. This property points to the holistic approaches which require giving parallel descriptions of the same system on different levels of its organization. There is strong evidence-consolidated also in the present review-that different, even apparently disparate complex systems can have astonishingly similar characteristics both in their structure and in their behaviour. One can thus expect the existence of some common, universal laws that govern their properties. Physics methodology proves helpful in addressing many of the related issues. In this review, we advocate some of the computational methods which in our opinion are especially fruitful in extracting information on selected-but at the same time most representative-complex systems like human brain, financial markets and natural language, from the time series representing the observables associated with these systems. The properties we focus on comprise the collective effects and their coexistence with noise, long-range interactions, the interplay between determinism and flexibility in evolution, scale invariance, criticality, multifractality and hierarchical structure. The methods described either originate from “hard” physics-like the random matrix theory-and then were transmitted to other fields of science via the field of complex systems research, or they originated elsewhere but

  16. Exploring Innovation – A Language Approach

    DEFF Research Database (Denmark)

    Mabogunje, Ade; Hansen, Poul H. Kyvsgård; Berg, Pekka

    2013-01-01

    ” Innovation Management is a complex task that requires improved methods to support the exploration of multiple innovation dimensions. We suggest firms to adopt a language inspired approach in order to improve existing methods. The language approach is supported by a graphical innovation profile...... that maps the innovation features and choices. The paper demonstrates the applications and perspectives of this approach with reference to a qualitative case study.”...

  17. Investment Portfolio Evaluation by the Fuzzy Approach

    Directory of Open Access Journals (Sweden)

    Lambovska Maya

    2011-09-01

    Full Text Available This paper presents a new fuzzy approach for the evaluation of investment portfolio, where the approach is viewed by the authors as a sub-phase of the management process of these portfolios. The approach defines the mutual and delayed effects among the significant variables of the investment portfolio. The evaluation of the effects is described as fuzzy trapezoidal numbers and they are aggregated by mathematical operations with incidence matrices and fuzzy functions “experton”.

  18. Fragment-based approaches to enzyme inhibition

    OpenAIRE

    Ciulli, Alessio; Abell, Chris

    2007-01-01

    Fragment-based approaches have provided a new paradigm for small-molecule drug discovery. The methodology is complementary to high-throughput screening approaches, starting from fragments of low molecular complexity and high ligand efficiency, and building up to more potent inhibitors. The approach, which depends heavily on a number of biophysical techniques, is now being taken up by more groups in both industry and academia. This article describes key aspects of the process and highlights re...

  19. Collective Flows in a Transport Approach

    OpenAIRE

    Plumari, S.; Baran, V.; Di Toro, M.; Greco, V.

    2010-01-01

    We introduce a transport approach at fixed shear viscosity to entropy ratio $\\etas$ to study the generation of collective flows in ultra-relativistic heavy-ion collisions. Transport theory supplies a covariant approach valid also at large $\\etas$ and at intermediate transverse momentum $p_T$, where deviations from equilibrium is no longer negligible. Such an approach shows that at RHIC energies a temperature dependent $\\etas$ enhances significantly the $v_4/v_2^2$ respect to the case of const...

  20. Dynamical System Approaches to Combinatorial Optimization

    DEFF Research Database (Denmark)

    Starke, Jens

    2013-01-01

    Several dynamical system approaches to combinatorial optimization problems are described and compared. These include dynamical systems derived from penalty methods; the approach of Hopfield and Tank; self-organizing maps, that is, Kohonen networks; coupled selection equations; and hybrid methods...... of large times as an asymptotically stable point of the dynamics. The obtained solutions are often not globally optimal but good approximations of it. Dynamical system and neural network approaches are appropriate methods for distributed and parallel processing. Because of the parallelization...

  1. A Geometric Approach to Noncommutative Principal Bundles

    CERN Document Server

    Wagner, Stefan

    2011-01-01

    From a geometrical point of view it is, so far, not sufficiently well understood what should be a "noncommutative principal bundle". Still, there is a well-developed abstract algebraic approach using the theory of Hopf algebras. An important handicap of this approach is the ignorance of topological and geometrical aspects. The aim of this thesis is to develop a geometrically oriented approach to the noncommutative geometry of principal bundles based on dynamical systems and the representation theory of the corresponding transformation group.

  2. Critical Approaches to Security in Europe

    OpenAIRE

    Malksoo, Maria; C.A.S.E. Collective

    2006-01-01

    In the last decade, critical approaches have substantially reshaped the\\ud theoretical landscape of security studies in Europe. Yet, despite an\\ud impressive body of literature, there remains fundamental disagreement\\ud as to what counts as critical in this context. Scholars are still\\ud arguing in terms of ‘schools’, while there has been an increasing and\\ud sustained cross-fertilization among critical approaches. Finally, the\\ud boundaries between critical and traditional approaches to secu...

  3. A NEW APPROACH TO VIRTUAL EDUCATION

    Directory of Open Access Journals (Sweden)

    Vladimir V. Kureychik

    2014-01-01

    Full Text Available The article discusses several approaches to training, namely the virtual. Concrete examples of virtual learning systems were described, we disclosed their features, advantages and disadvantages. A new suggested approach integrates the features of existing systems, and opens new horizons and opportunities to obtain certain skills and abilities. Introduction of a new approach to the educational process will improve the quality and effectiveness of learning. 

  4. DIGITAL INTERACTIVE STORYTELLING APPROACHES: A SYSTEMATIC REVIEW

    Directory of Open Access Journals (Sweden)

    Islam Sharaha1

    2016-08-01

    Full Text Available Interactive Digital Storytelling (IDS is concerned with the creation of a new media art form that allows real-time interaction with a developing narratives. IDS is important learning, training, testing and entertainment tool. This paper makes a systematic review that compares several approaches used in (IDs in terms of user interaction type, degree of interaction importance, classification of approaches types, and comparing approaches in terms of some performance factors.

  5. The probabilistic approach to human reasoning.

    Science.gov (United States)

    Oaksford, M; Chater, N

    2001-08-01

    A recent development in the cognitive science of reasoning has been the emergence of a probabilistic approach to the behaviour observed on ostensibly logical tasks. According to this approach the errors and biases documented on these tasks occur because people import their everyday uncertain reasoning strategies into the laboratory. Consequently participants' apparently irrational behaviour is the result of comparing it with an inappropriate logical standard. In this article, we contrast the probabilistic approach with other approaches to explaining rationality, and then show how it has been applied to three main areas of logical reasoning: conditional inference, Wason's selection task and syllogistic reasoning.

  6. A Mixed Approach Of Automated ECG Analysis

    Science.gov (United States)

    De, A. K.; Das, J.; Majumder, D. Dutta

    1982-11-01

    ECG is one of the non-invasive and risk-free technique for collecting data about the functional state of the heart. However, all these data-processing techniques can be classified into two basically different approaches -- the first and second generation ECG computer program. Not the opposition, but simbiosis of these two approaches will lead to systems with the highest accuracy. In our paper we are going to describe a mixed approach which will show higher accuracy with lesser amount of computational work. Key Words : Primary features, Patients' parameter matrix, Screening, Logical comparison technique, Multivariate statistical analysis, Mixed approach.

  7. SOME ASPECTS OF AGILE APPROACH IN PRAXIS

    Directory of Open Access Journals (Sweden)

    Jaroslava Kniežová

    2015-09-01

    Full Text Available In modern times, competitiveness in the market depends on having a good information system. The companies developing and supplying information systems are in competition too, and having an effective system of delivery is critical for obtaining lucrative offers. Therefore, the software development companies continuously try to improve their development process to supply the product in a short time and with high quality. The agile approach potentially shortens this time and is very often used. This approach has almost replaced the traditional process. More and more companies implement agile approach in these times to be competitive in the software development market and hasten product delivering.The traditional and agile approaches differ in certain perspectives. Hence, the question arises as to whether the agile approach is the best for the software development company in every case. This article contains a comparison of these two approaches, as well as a case study relating to the agile approach in a real software development company, which had previously used the traditional approach. The article also describes situation where replacing the traditional approach with agile would improve results.

  8. Concurrency-based approaches to parallel programming

    Science.gov (United States)

    Kale, L.V.; Chrisochoides, N.; Kohl, J.; Yelick, K.

    1995-01-01

    The inevitable transition to parallel programming can be facilitated by appropriate tools, including languages and libraries. After describing the needs of applications developers, this paper presents three specific approaches aimed at development of efficient and reusable parallel software for irregular and dynamic-structured problems. A salient feature of all three approaches in their exploitation of concurrency within a processor. Benefits of individual approaches such as these can be leveraged by an interoperability environment which permits modules written using different approaches to co-exist in single applications.

  9. Bioequivalence approach for whole effluent toxicity testing

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, R.; Wang, Q.; Fulk, F.; Deng, C.; Denton, D.

    2000-01-01

    Increased use of whole effluent toxicity (WET) tests in the regulatory arena has brought increased concern over the statistical analysis of WET test data and the determination of toxicity. One concern is the issue of statistical power. A number of WET tests may pass the current hypothesis test approach because they lack statistical power to detect relevant toxic effects because of large within-test variability. Additionally, a number of WET tests may fail the current approach because they possess excessive statistical power, as a result of small within-test variability, and detect small differences that may not be biologically relevant. The strengths and limitations of both the traditional hypothesis test approach and the bioequivalence approach for use in the National Pollutant Discharge Elimination System program were evaluated. Data from 5,213 single-concentration, short-term chronic WET tests with Ceriodaphnia dubia provided the database for analysis. Comparison of results between the current approach and the bioequivalence approach indicates that the current approach to WET testing is generally sound but that adopting the proposed bioequivalence approach resolves concerns of statistical power. Specifically, within this data set, applying the bioequivalence approach resulted in failure for tests with relatively large test variability and a pass for tests with relatively small within-test variability.

  10. An approximate analytical approach to resampling averages

    DEFF Research Database (Denmark)

    Malzahn, Dorthe; Opper, M.

    2004-01-01

    Using a novel reformulation, we develop a framework to compute approximate resampling data averages analytically. The method avoids multiple retraining of statistical models on the samples. Our approach uses a combination of the replica "trick" of statistical physics and the TAP approach for appr......Using a novel reformulation, we develop a framework to compute approximate resampling data averages analytically. The method avoids multiple retraining of statistical models on the samples. Our approach uses a combination of the replica "trick" of statistical physics and the TAP approach...

  11. Constrained neural approaches to quadratic assignment problems.

    Science.gov (United States)

    Ishii, S; Sato, M

    1998-08-01

    In this paper, we discuss analog neural approaches to the quadratic assignment problem (QAP). These approaches employ a hard constraints scheme to restrict the domain space, and are able to obtain much improved solutions over conventional neural approaches. Since only a few strong heuristics for QAP have been known to date, our approaches are good alternatives, capable of obtaining fairly good solutions in a short period of time. Some of them can also be applied to large-scale problems, say of size N>/=300.

  12. Global energy modeling - A biophysical approach

    Energy Technology Data Exchange (ETDEWEB)

    Dale, Michael

    2010-09-15

    This paper contrasts the standard economic approach to energy modelling with energy models using a biophysical approach. Neither of these approaches includes changing energy-returns-on-investment (EROI) due to declining resource quality or the capital intensive nature of renewable energy sources. Both of these factors will become increasingly important in the future. An extension to the biophysical approach is outlined which encompasses a dynamic EROI function that explicitly incorporates technological learning. The model is used to explore several scenarios of long-term future energy supply especially concerning the global transition to renewable energy sources in the quest for a sustainable energy system.

  13. Complementary and Alternative Approaches to Health

    Science.gov (United States)

    ... Fight Stress / Stress and Your Brain / Can Prolonged Stress Affect Whether Breast Cancer Returns? / Complementary and Alternative Approaches to Health Winter 2008 Issue: Volume 3 Number 1 Page ...

  14. Diabatic constrained relativistic mean field approach

    CERN Document Server

    L"u, H F; Meng, J

    2005-01-01

    A diabatic (configuration-fixed) constrained approach to calculate the potential energy surface (PES) of the nucleus is developed in the relativistic mean field model. The potential energy surfaces of $^{208}$Pb obtained from both adiabatic and diabatic constrained approaches are investigated and compared. The diabatic constrained approach enables one to decompose the segmented PES obtained in usual adiabatic approaches into separate parts uniquely characterized by different configurations, to define the single particle orbits at very deformed region by their quantum numbers, and to obtain several well defined deformed excited states which can hardly be expected from the adiabatic PES's.

  15. A Machine Learning Approach to Automated Negotiation

    Institute of Scientific and Technical Information of China (English)

    Zhang Huaxiang(张化祥); Zhang Liang; Huang Shangteng; Ma Fanyuan

    2004-01-01

    Automated negotiation between two competitive agents is analyzed, and a multi-issue negotiation model based on machine learning, time belief, offer belief and state-action pair expected Q value is developed. Unlike the widely used approaches such as game theory approach, heuristic approach and argumentation approach, This paper uses a machine learning method to compute agents' average Q values in each negotiation stage. The delayed reward is used to generate agents' offer and counteroffer of every issue. The effect of time and discount rate on negotiation outcome is analyzed. Theory analysis and experimental data show this negotiation model is practical.

  16. Probabilistic approach to earthquake prediction.

    Directory of Open Access Journals (Sweden)

    G. D'Addezio

    2002-06-01

    Full Text Available The evaluation of any earthquake forecast hypothesis requires the application of rigorous statistical methods. It implies a univocal definition of the model characterising the concerned anomaly or precursor, so as it can be objectively recognised in any circumstance and by any observer.A valid forecast hypothesis is expected to maximise successes and minimise false alarms. The probability gain associated to a precursor is also a popular way to estimate the quality of the predictions based on such precursor. Some scientists make use of a statistical approach based on the computation of the likelihood of an observed realisation of seismic events, and on the comparison of the likelihood obtained under different hypotheses. This method can be extended to algorithms that allow the computation of the density distribution of the conditional probability of earthquake occurrence in space, time and magnitude. Whatever method is chosen for building up a new hypothesis, the final assessment of its validity should be carried out by a test on a new and independent set of observations. The implementation of this test could, however, be problematic for seismicity characterised by long-term recurrence intervals. Even using the historical record, that may span time windows extremely variable between a few centuries to a few millennia, we have a low probability to catch more than one or two events on the same fault. Extending the record of earthquakes of the past back in time up to several millennia, paleoseismology represents a great opportunity to study how earthquakes recur through time and thus provide innovative contributions to time-dependent seismic hazard assessment. Sets of paleoseimologically dated earthquakes have been established for some faults in the Mediterranean area: the Irpinia fault in Southern Italy, the Fucino fault in Central Italy, the El Asnam fault in Algeria and the Skinos fault in Central Greece. By using the age of the

  17. Collapse of a Bose gas: Kinetic approach

    Indian Academy of Sciences (India)

    Shyamal Biswas

    2012-08-01

    We have analytically explored the temperature dependence of critical number of particales for the collapse of a harmonically trapped attractively interacting Bose gas below the condensation point by introducing a kinetic approach within the Hartee-Fock approximation. The temperature dependence obtained by this easy approach is consistant with that obtained from the scaling theory.

  18. Research on the Theory of Communicative Approach

    Institute of Scientific and Technical Information of China (English)

    Wang Changxue

    2014-01-01

    As speaking and listening are the two basic and essential skills in English learning,the communicative approach which focus on the learners’communicative competence take a very significant status. This paper aims to review and analyze the communicative approach and promote it to apply in the English teaching class.

  19. Amartya Sen's Capability Approach and Education

    Science.gov (United States)

    Walker, Melanie

    2005-01-01

    The human capabilities approach developed by the economist Amartya Sen links development, quality of life and freedom. This article explores the key ideas in the capability approach of: capability, functioning, agency, human diversity and public participation in generating valued capabilities. It then considers how these ideas relate specifically…

  20. An Ethnographic Descriptive Approach to Video Microanalysis

    DEFF Research Database (Denmark)

    Holck, Ulla

    2007-01-01

    In the ethnographically informed approach to observational research one studies everyday settings, and seeks to understand actions and meanings in their social context (Silverman 1993; Wolcott 1990). This approach is a strong tool for investigating interactions of a more or less implicit character...

  1. Interpreting Native American Literature: An Archetypal Approach.

    Science.gov (United States)

    Sevillano, Mando

    1986-01-01

    Compares two approaches to discussing Indian literature and religion. Demonstrates Jungian archetypal approach as transcultural method of analyzing Indian literature. Relates and analyzes Hopi traditional story. Emphasizes accessibility of Native American literature to the non-Indian while supporting multicultural plurality of interpretations.…

  2. Neuroevolutional Approach to Cerebral Palsy and Speech.

    Science.gov (United States)

    Mysak, Edward D.

    Intended for cerebral palsy specialists, the book emphasizes the contribution that a neuroevolutional approach to therapy can make to habilitation goals of the child with cerebral palsy and applies the basic principles of the Bobath approach to therapy. The first section discusses cerebral palsy as a reflection of disturbed neuro-ontogenisis and…

  3. Reflections on Narrative Approaches to Moral Development.

    Science.gov (United States)

    Lourenco, Orlando

    1996-01-01

    Compares narrative approaches to Kohlberg's theory of moral development along five dimensions: values relevance, legitimacy, universality, rationality, and commensurability. Argues that, contrary to Kohlberg's theory, narrative approaches may lead to contradiction in epistemology, nihilism in moral choices, and opportunism in relationships.…

  4. Discursive Study of Religion : Approaches, Definitions, Implications

    NARCIS (Netherlands)

    von Stuckrad, Kocku

    2013-01-01

    The article explores recent approaches to historical analysis of discourse that have been developed in disciplines such as the sociology of knowledge and historical epistemology. These approaches have only sporadically been taken seriously in the academic study of religion, although they have a grea

  5. The Social Shaping Approach to Technology Foresight

    DEFF Research Database (Denmark)

    Jørgensen, Michael Søgaard; Jørgensen, Ulrik; Clausen, Christian

    2009-01-01

    The social shaping of technology (SST) approach has been developed as a response and extension to the ideas of techno-economic rationality and linear conceptions of technology development and its consequences. The SST approach seems especially promising in areas of technology where visions are ma...

  6. A Complemental Approach to Instructional Development.

    Science.gov (United States)

    Hassan, M. H.

    In its relatively short history, instructional development has been greatly influenced by operant conditioning theory and methodology. This approach has been described by some as simplistic, inhuman, and inflexible. The humanistic approach, on the other hand, focuses on affective, emotional, and intellectual learning experiences. But it seems to…

  7. Analysis of radial basis function interpolation approach

    Institute of Scientific and Technical Information of China (English)

    Zou You-Long; Hu Fa-Long; Zhou Can-Can; Li Chao-Liu; Dunn Keh-Jim

    2013-01-01

    The radial basis function (RBF) interpolation approach proposed by Freedman is used to solve inverse problems encountered in well-logging and other petrophysical issues. The approach is to predict petrophysical properties in the laboratory on the basis of physical rock datasets, which include the formation factor, viscosity, permeability, and molecular composition. However, this approach does not consider the effect of spatial distribution of the calibration data on the interpolation result. This study proposes a new RBF interpolation approach based on the Freedman's RBF interpolation approach, by which the unit basis functions are uniformly populated in the space domain. The inverse results of the two approaches are comparatively analyzed by using our datasets. We determine that although the interpolation effects of the two approaches are equivalent, the new approach is more flexible and beneficial for reducing the number of basis functions when the database is large, resulting in simplification of the interpolation function expression. However, the predicted results of the central data are not sufficiently satisfied when the data clusters are far apart.

  8. Apply the Communicative Approach in Listening Class

    Institute of Scientific and Technical Information of China (English)

    Wang; changxue; Su; na

    2014-01-01

    Speaking and listening are the two obstacles in the process of our learning and they are also the most important abilities that we should possess. Communicative approach aims to the ability of learners’ communicative competence, thus apply the communicative approach in listening class is an effective way in English teaching procedure.

  9. Apply the Communicative Approach in Listening Class

    Institute of Scientific and Technical Information of China (English)

    Wang changxue; Su na

    2014-01-01

    Speaking and listening are the two obstacles in the process of our learning and they are also the most important abilities that we should possess. Communicative approach aims to the ability of learners’communicative competence, thus apply the communicative approach in listening class is an effective way in English teaching procedure.

  10. "1984": A Confessional Reading and Teaching Approach.

    Science.gov (United States)

    Tanenbaum, Miles

    1989-01-01

    Describes an approach to teaching George Orwell's "1984," emphasizing the main characters' struggles through the themes of innocence and experience, conformity and rebellion, love and hate, discovery and creation, and death. Notes that this reader-response approach forces students into the process of self-examination. (MM)

  11. Dialogic approaches to the study of subjectivity

    DEFF Research Database (Denmark)

    Otrel-Cass, Kathrin

    2013-01-01

    Book review: Sullivan, P. (2012). Qualitative Data Analysis: Using a dialogic approach. Los Angeles: SAGE Publications Ltd. ISBN 978-1-84920-609-9......Book review: Sullivan, P. (2012). Qualitative Data Analysis: Using a dialogic approach. Los Angeles: SAGE Publications Ltd. ISBN 978-1-84920-609-9...

  12. Competence: Conceptual Approach and Practice in France

    Science.gov (United States)

    Le Deist, Francoise

    2009-01-01

    Purpose: The purpose of this article is to analyse the conceptual approaches to competence and practice in competence management in France. Design/methodology/approach: Extensive literature review, discussion with academic experts in the French competence network of AGRH and interviews concerning developments following the 2003 national agreement…

  13. A Psycho-Reeducative Approach to History.

    Science.gov (United States)

    Girouard, Pierre

    Discussed is the application of a psycho-reeducative approach to the teaching of history in a boarding school for bright elementary grade boys. Topics discussed include the historic process and the process of adaptation, historic activity in a reeducative context, the historic evolution of this approach (1961-1972), the integration of concepts to…

  14. Reconsidering Graduate Employability: The "Graduate Identity" Approach.

    Science.gov (United States)

    Holmes, Len

    2001-01-01

    Elaborates a cogent alternative to the skills agenda as an approach to graduate employability--the graduate identity approach. Using a conceptual and theoretical examination of the key notion of performance, presents the twin concepts of practices and identity as significant for understanding human behavior. Offers suggestions for curriculum…

  15. An Experiential Approach to Cultural Intelligence Education

    Science.gov (United States)

    MacNab, Brent R.

    2012-01-01

    Cultural intelligence (CQ) represents a promising advancement in the area of cross-cultural training and management. Experiential approaches for CQ development have been proposed as highly effective; however, there is a lack of CQ-specific approaches in the management literature. This work overviews the concept of cultural intelligence and its…

  16. On Cognitive Approach to Process Writing

    Institute of Scientific and Technical Information of China (English)

    刘胤辛

    2014-01-01

    Based on its theoretical foundation of psychology, linguistics and pedagogy, cognitive approach aims to develop the practical and comprehensive ability of employing foreign language. Viewed as a complex process, writing can be regarded as a cognitive activity which focuses on the process of writing rather than its final product. This paper intends to discuss the effects of cognitive approach on English writing.

  17. A Professional Approach to PR Writing.

    Science.gov (United States)

    Nager, Norman R.

    After reviewing some of the problems involved in a traditional approach to teaching, this paper introduces a teaching system based on a patterned approach to the public relations writing process. The system format which is presented involves an analysis of persuasive communication components, programmed questioning of traditional premises, and…

  18. Teaching Mathematical Induction: An Alternative Approach.

    Science.gov (United States)

    Allen, Lucas G.

    2001-01-01

    Describes experience using a new approach to teaching induction that was developed by the Mathematical Methods in High School Project. The basic idea behind the new approach is to use induction to prove that two formulas, one in recursive form and the other in a closed or explicit form, will always agree for whole numbers. (KHR)

  19. Basic Employability Skills: A Triangular Design Approach

    Science.gov (United States)

    Rosenberg, Stuart; Heimler, Ronald; Morote, Elsa-Sofia

    2012-01-01

    Purpose: This paper seeks to examine the basic employability skills needed for job performance, the reception of these skills in college, and the need for additional training in these skills after graduation. Design/methodology/approach: The research was based on a triangular design approach, in which the attitudes of three distinct groups--recent…

  20. Information Processing Approaches to Cognitive Development

    Science.gov (United States)

    1989-08-04

    This chapter reviews the history and current status of information- processing approaches to cognitive development . Because the approach is so...a detailed analysis of self-modifying production systems and their potential for formulating theories of cognitive development . Keywords: Information processing; Cognitive development ; Self modification; Production system.