WorldWideScience

Sample records for nonpolar fluorous media

  1. Synthesis of RDX by nitrolysis of hexamethylenetetramine in fluorous media.

    Science.gov (United States)

    Yi, Wen-Bin; Cai, Chun

    2008-02-11

    Perfluorooctanesulfonic acid (CF(3)(CF(2))(7)SO(3)H, PfOS) catalyses the highly efficient nitrolysis of hexamethylenetetramine in fluorous media, affording high yield of explosive RDX. The reaction can be carried out at room temperature in the absence of acetic anhydride and produces smaller amounts of waste acid and nitrate than in traditional process. The fluorous phase containing catalyst could be easily and efficiently recovered for reuse by simple phase separation.

  2. Critical concentration of ion-pairs formation in nonpolar media.

    Science.gov (United States)

    Dukhin, Andrei

    2014-07-01

    It is known that nonpolar liquids can be ionized by adding surfactants, either ionic or nonionic. Surfactant molecules serve as solvating agents, building inverse micelles around ions, and preventing their association back into neutral molecules. According to the Bjerrum-Onsager-Fuoss theory, these inverse micelle ions should form "ion pairs." This, in turn, leads to nonlinear dependence of the conductivity on the concentration. Surprisingly, ionic surfactants exhibit linear conductivity dependence, which implies that these inverse micelle ions do not form ion pairs. Theory predicts the existence of two ionic strength ranges, which are separated by a certain critical ion concentration. Ionic strength above the critical one is proportional to the square root of the ion concentration, whereas it becomes linear below the critical concentration. Critical ion concentration lies within the range of 10(-11) -10(-7) mol/L when ion size ranges from 1 to 3 nm. Critical ion concentration is related, but not equal, to a certain surfactant concentration (critical concentration of ion-pairs formation (CIPC)) because only a fraction of the surfactant molecules is incorporated into the micelles ions. The linear conductivity dependence for ionic surfactants indicates that the corresponding CIPC is above the range of studied concentrations, perhaps, due to rather large ion size. The same linearity is a sign that charged inverse micelles structure and fraction are concentration independent due to strong charge-dipole interaction in the charge micelle core. This also proves that CIPC is independent of critical concentration of micelle formation. Nonionic surfactants, on the other hand, exhibit nonlinear conductivity dependence apparently due to smaller ion sizes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Relative effectiveness of pretreatments on performance of Rhizomucor miehei lipase in nonpolar reaction media.

    Science.gov (United States)

    Garcia, Rafael A; Riley, Mark R

    2005-02-01

    Enzymes can be used in nonpolar reaction media to modify water-insoluble substrates. A variety of pretreatments, applied to the enzyme prior to introduction to the nonpolar media, can improve enzyme activity. However, the various pretreatments have not been studied using directly comparable conditions, nor have they been applied simultaneously to test for interactive effects. This work evaluates pretreatment of lipase with various classes of additives. The pretreated lipase is used to catalyze esterification between citronellol and acetic acid in a medium of n-hexane. The effectiveness of a particular pretreatment is presented in terms of relative performance (RP), which is equal to the number of times faster the pretreated lipase catalyzes the reaction relative to untreated lipase. The individual and interactive effects of the pretreatment factors were studied and compared. Buffer salts had a much stronger performance-enhancing effect than nonbuffer salts; pretreatment with 90% (w/w) sodium phosphate yielded lipase with an RP of approx 64. A strong interaction was found between the treatments with sodium phosphate and pH adjustment. These treatments may mitigate the inhibitory effect of acetic acid. Activating effects of phase interfaces and active-site protectants are shown to be complementary to other treatments, demonstrating that they likely act by distinct mechanisms.

  4. Application of classical thermodynamics to the conductivity in non-polar media

    Science.gov (United States)

    Gourdin-Bertin, S.; Chassagne, C.

    2016-06-01

    Electrical conductivity in non-polar media is a subject which recently regained interest. If most of experiments and theoretical developments were done more than 50 years ago, new experiments and theories have been recently published. As the electrical conductivity describes, at low field, the equilibrium state of a system, it is natural to apply theories based on equilibrium thermodynamics. In this article, well-established classical thermodynamics and solvations models are applied to recently published data. This enables to get a new insight in intriguing phenomena, such as the linear dependence of the conductivity on the concentration of ionic surfactant and the evaluation of conductivity for the mixture of two miscible fluids, such as alcohol and alcane, which have very different conductivities.

  5. Covalent and non-covalent functionalization and solubilization of double-walled carbon nanotubes in nonpolar and aqueous media

    Indian Academy of Sciences (India)

    L S Panchakarla; A Govindaraj

    2008-11-01

    Double-walled carbon nanotubes (DWNTs) have been functionalized by both covalent and non-covalent means. Covalent functionalization has been carried out by attaching an aliphatic amide function to DWNTs which enable solubilization in non-polar solvents. Solubilization in non-polar solvents has also been accomplished by non-covalent functionalization by using 1-pyrenebutanoicacid succinimidyl ester (PYBS). Non-covalent functionalization of DWNTs has been carried out by using polyethylene glycol (PEG) and polyoxyethylene(40)nonylphenyl ether (IGPAL), both of which enable solubilization in aqueous media. These functionalized DWNTs have been characterized by transmission electron microscopy, IR and Raman spectroscopy.

  6. Predicting Partitioning and Diffusion Properties of Nonpolar Chemicals in Biotic Media and Passive Sampler Phases by GC × GC.

    Science.gov (United States)

    Nabi, Deedar; Arey, J Samuel

    2017-02-14

    The chemical parameters needed to explain and predict bioavailability, biodynamics, and baseline toxicity are not readily available for most nonpolar chemicals detected in the environment. Here, we demonstrate that comprehensive two-dimensional gas chromatography (GC × GC) retention times can be used to predict 26 relevant properties for nonpolar chemicals, specifically: partition coefficients for diverse biotic media and passive sampler phases; aquatic baseline toxicity; and relevant diffusion coefficients. The considered biotic and passive sampler phases include membrane and storage lipids, serum and muscle proteins, carbohydrates, algae, mussels, polydimethylsiloxane, polyethylene, polyoxymethylene, polyacrylate, polyurethane, and semipermeable membrane devices. GC × GC-based chemical property predictions are validated with a compilation of 1038 experimental property data collected from the literature. As an example application, we overlay a map of baseline toxicity to fathead minnows onto the separated analyte signal of a polychlorinated alkanes (chlorinated paraffins) technical mixture that contains 7820 congeners. In a second application, GC × GC-estimated properties are used to parametrize multiphase partitioning models for mammalian tissues and organs. In a third example, we estimate chemical depuration kinetics for mussels. Finally, we illustrate an approach to screen the GC × GC chromatogram for nonpolar chemicals of potentially high concern, defined based on their GC × GC-estimated biopartitioning properties, diffusion properties, and baseline toxicity.

  7. Molecular and ionic hydrogen bond formation in fluorous solvents.

    Science.gov (United States)

    O'Neal, Kristi L; Weber, Stephen G

    2009-01-08

    There are only a few studies of noncovalent association in fluorous solvents and even fewer that are quantitative. A full understanding, particularly of stoichiometry and binding strength of noncovalent interactions in fluorous solvents could be very useful in improved molecular-receptor-based extractions, advancements in sensor technologies, crystal engineering, and supramolecular chemistry. This work investigates hydrogen bonding between heterocyclic bases and a perfluoropolyether with a terminal carboxylic acid group (Krytox 157FSH (1)), chiefly in FC-72 (a mixture of perfluorohexanes). In particular, we were interested in whether or not proton transfer occurs, and if so, under what conditions in H-bonded complexes. Continuous variations experiments show that in FC-72 weaker bases (pyrazine, pyrimidine, and quinazoline) form 1:1 complexes with 1, whereas stronger bases (quinoline, pyridine, and isoquinoline) form 1:3 complexes. Ultraviolet and infrared spectral signatures reveal that the 1:1 complexes are molecular (B.HA) whereas the 1:3 complexes are ionic (BH+.A-HAHA). Infrared spectra of 1:3 ionic complexes are discussed in detail. Literature and experimental data on complexes between N-heterocyclic bases and carboxylic acids in a range of solvents are compiled to compare solvent effects on proton transfer. Polar solvents support ionic hydrogen bonds at a 1:1 mol ratio. In nonpolar organic solvents, ionic hydrogen bonds are only observed in complexes with 1:2 (base/acid) stoichiometries. In fluorous solvents, a larger excess of acid, 1:3, is necessary to facilitate proton transfer in hydrogen bonds between carboxylic acids and the bases studied.

  8. Molecular Dynamics Simulations on Parallel Computers: a Study of Polar Versus Nonpolar Media Effects in Small Molecule Solvation.

    Science.gov (United States)

    Debolt, Stephen Edward

    Solvent effects were studied and described via molecular dynamics (MD) and free energy perturbation (FEP) simulations using the molecular mechanics program AMBER. The following specific topics were explored:. Polar solvents cause a blue shift of the rm nto pi^* transition band of simple alkyl carbonyl compounds. The ground- versus excited-state solvation effects responsible for the observed solvatochromism are described in terms of the molecular level details of solute-solvent interactions in several modeled solvents spanning the range from polar to nonpolar, including water, methanol, and carbon tetrachloride. The structure and dynamics of octanol media were studied to explore the question: "why is octanol/water media such a good biophase analog?". The formation of linear and cyclic polymers of hydrogen-bonded solvent molecules, micelle-like clusters, and the effects of saturating waters are described. Two small drug-sized molecules, benzene and phenol, were solvated in water-saturated octanol. The solute-solvent structure and dynamics were analysed. The difference in their partitioning free energies was calculated. MD and FEP calculations were adapted for parallel computation, increasing their "speed" or the time span accessible by a simulation. The non-cyclic polyether ionophore salinomycin was studied in methanol solvent via parallel FEP. The path of binding and release for a potassium ion was investigated by calculating the potential of mean force along the "exit vector".

  9. Fluorous Compounds and their Role in Separation Chemistry

    Science.gov (United States)

    Ubeda, Maria Angeles; Dembinski, Roman

    2006-01-01

    The main focus of fluorous chemistry targets resource and time-consuming separation, in order to improve the material economy and thus represents potentially environmentally friendly technology. Fluorous chemistry offers the advantage of easy separation based on different affirmatives of organics and fluorous molecules, where the process called…

  10. Fluorous Mixture Synthesis of Asymmetric Dendrimers

    Science.gov (United States)

    Jiang, Zhong-Xing; Yu, Yihua Bruce

    2010-01-01

    A divergent fluorous mixture synthesis (FMS) of asymmetric fluorinated dendrimers has been developed. Four generations of fluorinated dendrimers with the same fluorinated moiety were prepared with high efficiency, yield and purity. Comparison of the physicochemical properties of these dendrimers provided valuable information for their application and future optimization. This strategy has not only provided a practical method for the synthesis and purification of dendrimers, but also established the possibility of utilizing the same fluorinated moiety for FMS. PMID:20170088

  11. A Highly Fluorous Room-Temperature Ionic Liquid Exhibiting Fluorous Biphasic Behaviour and Its Use in Catalyst Recycling

    NARCIS (Netherlands)

    Koten, G. van; Broeke, J. van den; Winter, F.; Deelman, B.J.

    2002-01-01

    A novel fluorous room-temperature ionic liquid, 1-butyl-3-methyl-imidazolium tetrakis[p-{dimethyl(1H,1H,2H,2H-perfluorooctyl)silyl}phenyl]borate (1), was used as a solvent for the homogeneous hydrosilylation of 1-octene catalyzed by a fluorous version of Wilkinson's catalyst. The catalyst was recycl

  12. Molecular mechanism of carbon nanotube to activate Subtilisin Carlsberg in polar and non-polar organic media

    Science.gov (United States)

    Zhang, Liyun; Li, Yuzhi; Yuan, Yuan; Jiang, Yuanyuan; Guo, Yanzhi; Li, Menglong; Pu, Xuemei

    2016-11-01

    In the work, we mainly used molecular dynamics (MD) simulation and protein structure network (PSN) to study subtilisin Carlsberg (SC) immobilized onto carbon nanotube (CNT) in water, acetonitrile and heptane solvents, in order to explore activation mechanism of enzymes in non-aqueous media. The result indicates that the affinity of SC with CNT follows the decreasing order of water > acetonitrile > heptane. The overall structure of SC and the catalytic triad display strong robustness to the change of environments, responsible for the activity retaining. However, the distances between two β-strands of substrate-binding pocket are significantly expanded by the immobilization in the increasing order of water media. PSN analysis further reveals that the immobilization enhances structural communication paths to the substrate-binding pocket, leading to its larger change than the free-enzymes. Interestingly, the increase in the number of the pathways upon immobilization is not dependent on the absorbed extent but the desorbed one, indicating significant role of shifting process of experimental operations in influencing the functional region. In addition, some conserved and important hot-residues in the paths are identified, providing molecular information for functional modification.

  13. Perfluorinated quaternary ammonium salts of polyoxometalate anions: Fluorous biphasic oxidation catalysis with and without fluorous solvents

    Energy Technology Data Exchange (ETDEWEB)

    Maayan, Galia; Fish, Richard H.; Neumann, Ronny

    2003-05-28

    Perfluorinated quaternary ammonium cations, [CF{sub 3}(CF{sub 2}){sub 7}(CH{sub 2}){sub 3}]{sub 3}CH{sub 3}N{sup +} (RFN{sup +}), were synthesized and used as counter cations for the [WZnM{sub 2}(H{sub 2}O){sub 2}(ZnW{sub 9}O{sub 34}){sub 2}]{sup 12-} (M = Mn(II), Zn(II)), polyoxometalate. The (RFN{sup +}){sub 12}[WZnM{sub 2}(H{sub 2}O){sub 2}(ZnW9O{sub 34}){sub 2}] compounds were fluorous biphasic catalysts for alcohol and alkenol oxidation, and alkene epoxidation with aqueous hydrogen peroxide. Reaction protocols with or without a fluorous solvent were tested. The catalytic activity and selectivity was affected both by the hydrophobicity of the solvent and the substrate.

  14. Fluorous ionic liquids as solvents for the liquid-liquid extraction of metal ions by macrocyclic polyethers.

    Science.gov (United States)

    Heitzman, Holly; Young, Blake A; Rausch, David J; Rickert, Paul; Stepinski, Dominique C; Dietz, Mark L

    2006-04-15

    The predominant mode of strontium ion transfer from aqueous nitrate media into a series of 1-fluoroalkyl-3-methylimidazolium bis[(trifluoromethylsulfonyl)]imides containing dicyclohexano-18-crown-6 (DCH18C6) is shown to shift from cation exchange to strontium nitrato-crown ether complex partitioning as the length of the fluoroalkyl substituent is increased. Fluoroalkyl substituents are shown to be only slightly more effective than their non-fluorous analogs at inducing this shift. At the same time, the fluorinated ionic liquids (ILs) yield strontium distribution ratios as much as an order of magnitude lower than the corresponding 1-alkyl-3-methylimidazolium (C(n)mim(+)) salts. Fluorous ILs thus appear to offer no compelling advantages over C(n)mim(+) ionic liquids as extraction solvents.

  15. Compositions, methods, and systems comprising fluorous-soluble polymers

    Science.gov (United States)

    Swager, Timothy M.; Lim, Jeewoo; Takeda, Yohei

    2015-10-13

    The present invention generally relates to compositions, methods, and systems comprising polymers that are fluorous-soluble and/or organize at interfaces between a fluorous phase and a non-fluorous phase. In some embodiments, emulsions or films are provided comprising a polymer. The polymers, emulsions, and films can be used in many applications, including for determining, treating, and/or imaging a condition and/or disease in a subject. The polymer may also be incorporated into various optoelectronic device such as photovoltaic cells, organic light-emitting diodes, organic field effect transistors, or the like. In some embodiments, the polymers comprise pi-conjugated backbones, and in some cases, are highly emissive.

  16. Properties of PTFE tape as a semipermeable membrane in fluorous reactions

    Directory of Open Access Journals (Sweden)

    Brendon A. Parsons

    2015-06-01

    Full Text Available In a PTFE tape phase-vanishing reaction (PV-PTFE, a delivery tube sealed with PTFE tape is inserted into a vessel which contains the substrate. The reagent diffuses across the PTFE tape barrier into the reaction vessel. PTFE co-polymer films have been found to exhibit selective permeability towards organic compounds, which was affected by the presence of solvents. In this study, we attempted to establish general trends of permeability of PTFE tape to different compounds and to better describe the process of solvent transport in PV-PTFE bromination reactions. Though PTFE tape has been reported as impermeable to some compounds, such as dimethyl phthalate, solvent adsorption to the tape altered its permeability and allowed diffusion through channels of solvent within the PTFE tape. In this case, the solvent-filled pores of the PTFE tape are chemically more akin to the adsorbed solvent rather than to the PTFE fluorous structure. The solvent uptake effect, which was frequently observed in the course of PV-PTFE reactions, can be related to the surface tension of the solvent and the polarity of the solvent relative to the reagent. The lack of pores in bulk PTFE prevents solvents from altering its permeability and, therefore, bulk PTFE is impermeable to most solvents and reagents. However, bromine, which is soluble in liquid fluorous media, diffused through the bulk PTFE. A better understanding of the PTFE phase barrier will make it possible to further optimize the PV-PTFE reaction design.

  17. Dynamic Surface Tensions of Fluorous Surfactant Solutions

    Institute of Scientific and Technical Information of China (English)

    高艳安; 侯万国; 王仲妮; 李干佐; 韩布兴; 张高勇; 吕锋锋

    2005-01-01

    Dynamic surface properties of aqueous solutions of cationic fluorous surfactant CF3CF2CF20(CF(CF3)CF2O)2CF(CF3)CONH(CHE)3N+(C2H5)2CH3I- (abbrev. FC-4 ) were reported. The critical micelle concentration (cmc)(3.6×10-5 mol/L) and equilibdum surface tensions γeq were measured by Krtlss K12 tension apparatus. Dynamic surface tension γ(t) was measured in the range of 15 ms to 200 s using the MBP tensiometer. The surface excess Γ,as a function of concentration, was obtained from equilibrium tensiometry using the Gibbs equation. Data from these experiments were combined to analyze the γ(t) decays according to the asymptotic Ward and Tordai equation.The results show that at the initial adsorption stage, the dynamic surface tension data were all consistent with this diffusion-controlled mechanism, and at the end of the adsorption process, there were some evidences for an adsorption barrier, suggesting a mixed diffusion-controlled adsorption mechanism. Using measured quantities, the barrier strength was estimated as between 25 and 35 kJ/mol at 25℃. The surface pressure plays an important role in contributing to the barrier.

  18. Development of Fluorous Lewis Acid-Catalyzed Reactions

    Directory of Open Access Journals (Sweden)

    Joji Nishikido

    2006-08-01

    Full Text Available Organic synthetic methodology in the 21st century aims to conform to the principles of green sustainable chemistry (GSC and we may expect that in the future, the realization of GSC will be an important objective for chemical industries. An important aim of synthetic organic chemistry is to implement waste-free and environmentally-benign industrial processes using Lewis acids as versatile as aluminum choride. A key technological objective of our work in this area has been to achieve a “catalyst recycling system that utilizes the high activity and structural features of fluorous Lewis acid catalysts”. Thus, we have developed a series of novel fluorous Lewis acid catalysts, namely the ytterbium(III, scandium(III, tin(IV or hafnium(IV bis(perfluoroalkanesulfonylamides or tris(perfluoro- alkanesulfonylmethides. Our catalysts are recyclable and effective for acylations of alcohols and aromatics, Baeyer-Villiger reactions, direct esterifications and transesterifications in a fluorous biphasic system (FBS, in supercritical carbon dioxide and on fluorous silica gel supports.

  19. Fluorous polymeric membranes for ionophore-based ion-selective potentiometry: how inert is Teflon AF?

    Science.gov (United States)

    Lai, Chun-Ze; Koseoglu, Secil S; Lugert, Elizabeth C; Boswell, Paul G; Rábai, József; Lodge, Timothy P; Bühlmann, Philippe

    2009-02-04

    Fluorous media are the least polar and polarizable condensed phases known. Their use as membrane materials considerably increases the selectivity and robustness of ion-selective electrodes (ISEs). In this research, a fluorous amorphous perfluoropolymer was used for the first time as a matrix for an ISE membrane. Electrodes for pH measurements with membranes composed of poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole]-co-poly(tetrafluoroethylene) (87% dioxole monomer content; known as Teflon AF2400) as polymer matrix, a linear perfluorooligoether as plasticizer, sodium tetrakis[3,5-bis(perfluorohexyl)phenyl]borate providing for ionic sites, and bis[(perfluorooctyl)propyl]-2,2,2-trifluoroethylamine as H+ ionophore were investigated. All electrodes had excellent potentiometric selectivities, showed Nernstian responses to H+ over a wide pH range, exhibited enhanced mechanical stability, and maintained their selectivity over at least 4 weeks. For membranes of low ionophore concentration, the polymer affected the sensor selectivity noticeably at polymer concentrations exceeding 15%. Also, the membrane resistance increased quite strongly at high polymer concentrations, which cannot be explained by the Mackie-Meares obstruction model. The selectivities and resistances depend on the polymer concentration because of a functional group associated with Teflon AF2400, with a concentration of one functional group per 854 monomer units of the polymer. In the fluorous environment of these membranes, this functional group binds to Na+, K+, Ca2+, and the unprotonated ionophore with binding constants of 10(3.5), 10(1.8), 10(6.8), and 10(4.4) M(-1), respectively. Potentiometric and spectroscopic evidence indicates that these functional groups are COOH groups formed by the hydrolysis of carboxylic acid fluoride (COF) groups originally present in Teflon AF2400. The use of higher ionophore concentrations removes the undesirable effect of these COOH groups almost completely

  20. Synthesis of deep-cavity fluorous calix[4]arenes as molecular recognition scaffolds

    Directory of Open Access Journals (Sweden)

    2008-10-01

    Full Text Available Several lower-rim perfluoroalkylated (fluorous calix[4]arenes have been synthesized by O-alkylation of the parent calix[4]arene. The compounds are formed in the cone conformation. They are soluble in several fluorous solvents and show promise for use in sensing, selective extractions and other applications.

  1. Enantioselective α-Chlorination of Aldehydes with Recyclable Fluorous (S)-Pyrrolidine-Thiourea Bifunctional Organocatalyst.

    Science.gov (United States)

    Wang, Liang; Cai, Chun; Curran, Dennis P; Zhang, Wei

    2010-01-01

    A novel fluorous (S)-pyrrolidine-thiourea bifunctional organocatalyst is prepared. The catalyst shows good activity and enantioselectivity for direct α-chlorination of aldehydes using N-chlorosuccinimide (NCS) as the chlorine source. It can be recovered from the reaction mixture by fluorous solid-phase extraction with excellent purity for direct reuse.

  2. Iridium(I) complexes with anionic N-heterocyclic carbene ligands as catalysts for the hydrogenation of alkenes in nonpolar media.

    Science.gov (United States)

    Kolychev, Eugene L; Kronig, Sabrina; Brandhorst, Kai; Freytag, Matthias; Jones, Peter G; Tamm, Matthias

    2013-08-21

    A series of lithium complexes of anionic N-heterocyclic carbenes that contain a weakly coordinating borate moiety (WCA-NHC) was prepared in one step from free N-heterocyclic carbenes by deprotonation with n-butyl lithium followed by borane addition. The reaction of the resulting lithium-carbene adducts with [M(COD)Cl]2 (M = Rh, Ir; COD = 1,5-cyclooctadiene) afforded zwitterionic rhodium(I) and iridium(I) complexes of the type [(WCA-NHC)M(COD)], in which the metal atoms exhibit an intramolecular interaction with the N-aryl groups of the carbene ligands. For M = Rh, the neutral complex [(WCA-NHC)Rh(CO)2] and the ate complex (NEt4)[(WCA-NHC)Rh(CO)2Cl] were prepared, with the latter allowing an assessment of the donor ability of the ligand by IR spectroscopy. The zwitterionic iridium-COD complexes were tested as catalysts for the homogeneous hydrogenation of alkenes, which can be performed in the presence of nonpolar solvents or in the neat alkene substrate. Thereby, the most active complex showed excellent stability and activity in hydrogenation of alkenes at low catalyst loadings (down to 10 ppm).

  3. Simultaneous preparation of four truncated analogues of discodermolide by fluorous mixture synthesis.

    Science.gov (United States)

    Curran, Dennis P; Furukawa, Takashi

    2002-06-27

    [structure: see text] Four truncated analogues of the natural product discodermolide were synthesized in a single synthetic sequence. Precursors bearing four different groups at C22, each with a unique fluorous p-methoxybenzyl substituent on the C17 hydroxy group, were mixed and taken through an nine-step sequence. Demixing by fluorous chromatography followed by deprotection and purification provided the individual analogues in 3-7% overall yields and with a savings of 24 synthetic steps. Fluorous mixture synthesis is recommended as a new technique to make multiple natural product analogues in a single multistep synthesis.

  4. More Fluorous Surface Modifier Makes it Less Oleophobic: Fluorinated-Siloxane Copolymer/PDMS Coatings

    OpenAIRE

    Zhang, Wei; Zheng, Ying; Orsini, Lorenzo; Morelli, Andrea; Galli, Giancarlo; Chiellini, Emo; Carpenter, Everett E.; Wynne, Kenneth J.

    2010-01-01

    A copolyacrylate with semifluorinated and polydimethylsiloxane side chains (D5-3) was used as a surface modifier for a condensation cured PDMS coating. The decyl fluorous group is represented by “D”; “5” is a 5 kDa silicone, and “3” the mole ratio of fluorous to silicone side chain. Wetting behavior was assessed by dynamic contact angle (DCA) analysis using isopropanol, which differentiates silicone and fluorous wetting behavior. Interestingly, a maximum in surface oleophobicity was found at ...

  5. P-Fluorous Phosphines as Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal Catalysts: Synthesis of Rh(I, Ir(I, Pt(II, and Au(I Complexes Bearing P-Fluorous Phosphine Ligands

    Directory of Open Access Journals (Sweden)

    Shin-ichi Kawaguchi

    2017-01-01

    Full Text Available P-Fluorous phosphine (R2PRf, in which the perfluoroalkyl group is directly bonded to the phosphorus atom, is a promising ligand because it has a hybrid functionality, i.e., electron-poor and fluorous ligands. However, examples of P-fluorous phosphine–metal complexes are still rare, most probably because the P-fluorous group is believed to decrease the coordination ability of the phosphines dramatically. In contrast, however, we have succeeded in synthesizing a series of P-fluorous phosphine–coordinated metal complexes such as rhodium, iridium, platinum, and gold. Furthermore, the electronic properties of R2PnC10F21 are investigated by X-ray analysis of PtCl2(Ph2PnC10F212 and the infrared CO stretching frequency of RhCl(CO(R2PnC10F212. IrCl(CO(Ph2PnC10F212- and AuCl(R2PnC10F21-catalyzed reactions are also demonstrated.

  6. Fluorous-assisted metal chelate affinity extraction technique for analysis of protein kinase activity.

    Science.gov (United States)

    Hayama, Tadashi; Kiyokawa, Ena; Yoshida, Hideyuki; Imakyure, Osamu; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2016-08-15

    We have developed a fluorous affinity-based extraction method for measurement of protein kinase activity. In this method, a fluorescent peptide substrate was phosphorylated by a protein kinase, and the obtained phosphopeptide was selectively captured with Fe(III)-immobilized perfluoroalkyliminodiacetic acid reagent via a metal chelate affinity technique. Next, the captured phosphopeptide was selectively extracted into a fluorous solvent mixture, tetradecafluorohexane and 1H,1H,2H,2H-tridecafluoro-1-n-octanol (3:1, v/v), using the specificity of fluorous affinity (fluorophilicity). In contrast, the remained substrate peptide in the aqueous (non-fluorous) phase was easily measured fluorimetrically. Finally, the enzyme activity could be assayed by measuring the decrease in fluorescence. The feasibility of this method was demonstrated by applying the method for measurement of the activity of cAMP-dependent protein kinase (PKA) using its substrate peptide (kemptide) pre-labeled with carboxytetramethylrhodamine (TAMRA).

  7. Thieme Chemistry Journal Awardees - Where are They Now? Catalytic Transport with an Amine Carrier in a Fluorous Triphasic Reaction.

    Science.gov (United States)

    Montanari, Vittorio; Yu, Marvin S; Curran, Dennis P

    2009-03-01

    Several aromatic aldehydes are transported by a fluorous amine from one organic phase through a fluorous phase to another organic phase. The derived imines react with phenylhydrazine to immobilize the transported product as a hydrazone and release the amine for reuse. In this way, catalytic transport is accomplished for the first time.

  8. Fluorous microgel star polymers: selective recognition and separation of polyfluorinated surfactants and compounds in water.

    Science.gov (United States)

    Koda, Yuta; Terashima, Takaya; Sawamoto, Mitsuo

    2014-11-01

    Immiscible with either hydrophobic or hydrophilic solvents, polyfluorinated compounds (PFCs) are generally "fluorous", some of which have widely been employed as surfactants and water/oil repellents. Given the prevailing concern about the environmental pollution and the biocontamination by PFCs, their efficient removal and recycle from industrial wastewater and products are critically required. This paper demonstrates that fluorous-core star polymers consisting of a polyfluorinated microgel core and hydrophilic PEG-functionalized arms efficiently and selectively capture PFCs in water into the cores by fluorous interaction. For example, with over 10 000 fluorine atoms in the core and approximately 100 hydrophilic arms, the fluorous stars remove perfluorooctanoic acid (PFOA) and related PFCs in water from 10 ppm to as low as a parts per billion (ppb) level, or an over 98% removal. Dually functionalized microgel-core star polymers with perfluorinated alkanes and additional amino (or ammonium) groups cooperatively recognize PFOA or its ammonium salt and, in addition, release the guests upon external stimuli. The "smart" performance shows that the fluorous-core star polymers are promising PFC separation, recovery, and recycle materials for water purification toward sustainable society.

  9. Thermomolecular Orientation of Nonpolar Fluids

    NARCIS (Netherlands)

    Römer, F.; Bresme, F.; Muscatello, J.; Bedeaux, D.; Rubi, J.M.

    2012-01-01

    We investigate the response of molecular fluids to temperature gradients. Using nonequilibrium molecular dynamics computer simulations we show that nonpolar diatomic fluids adopt a preferred orientation as a response to a temperature gradient. We find that the magnitude of this thermomolecular orien

  10. Polymers modified with double-tailed fluorous compounds for efficient DNA and siRNA delivery.

    Science.gov (United States)

    He, Bingwei; Wang, Yitong; Shao, Naimin; Chang, Hong; Cheng, Yiyun

    2015-08-01

    Cationic polymers are widely used as gene carriers, however, these polymers are usually associated with low transfection efficacy and non-negligible toxicity. Fluorination on polymers significantly improves their performances in gene delivery, but a high density of fluorous chains must be conjugated on a single polymer. Here we present a new strategy to construct fluorinated polymers with minimal fluorous chains for efficient DNA and siRNA delivery. A double-tailed fluorous compound 2-chloro-4,6-bis[(perfluorohexyl)propyloxy]-1,3,5-triazine (CBT) was conjugated on dendrimers of different generations and low molecular weight polyethylenimine via a facile synthesis. The yielding products with average numbers of 1-2 conjugated CBT moieties showed much improved EGFP and luciferase transfection efficacy compared to unmodified polymers. In addition, these polymers show high siRNA delivery efficacy on different cell lines. Among the synthesized polymers, generation 1 (G1) dendrimer modified with an average number of 1.9 CBT moieties (G1-CBT1.9) shows the highest efficacy when delivering both DNA and siRNA and its efficacy approaches that of Lipofectamine 2000. G1-CBT1.9 also shows efficient gene silencing in vivo. All of the CBT-modified polymers exhibit minimal toxicity on the cells at their optimal transfection conditions. This study provides a new strategy to design efficient fluorous polymers for DNA and siRNA delivery.

  11. Synthesis and application of a new fluorous-tagged ammonia equivalent

    DEFF Research Database (Denmark)

    Nielsen, Simon Dalsgaard; Smith, Garrick; Begtrup, Mikael

    2010-01-01

    A novel fluorous-tagged ammonia equivalent has been developed. It is based on a nitrogen-oxygen bond, which can be cleaved in a traceless manner by a molybdenum complex or samarium diiodide. The application in the synthesis of ureas, amides, sulfonamides, and carbamates is described. The scope...

  12. Fluorous Mixture Synthesis of Four Stereoisomers of the C21-C40 Fragment of Tetrafibricin.

    Science.gov (United States)

    Zhang, Kai; Curran, Dennis P

    2010-03-01

    Four stereoisomers of the C21-C40 fragment are synthesized in a single exercise with the aid of fluorous tagging to encode configurations at C37 and C33. After demixing and detagging, the isomers were found to have substantially identical (1)H NMR spectra. However, there were some small but reliable differences in their (13)C NMR spectra.

  13. Thermomolecular orientation of nonpolar fluids.

    Science.gov (United States)

    Römer, Frank; Bresme, Fernando; Muscatello, Jordan; Bedeaux, Dick; Rubí, J Miguel

    2012-03-09

    We investigate the response of molecular fluids to temperature gradients. Using nonequilibrium molecular dynamics computer simulations we show that nonpolar diatomic fluids adopt a preferred orientation as a response to a temperature gradient. We find that the magnitude of this thermomolecular orientation effect is proportional to the strength of the temperature gradient and the degree of molecular anisotropy, as defined by the different size or mass of the molecular atomic sites. We show that the preferred orientation of the molecules follows the same trends observed in the Soret effect of binary mixtures. We argue this is a general effect that should be observed in a wide range of length scales.

  14. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hung-Yu; Sheng, Yu-Jane, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan (China); Tu, Sheng-Hung [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan (China); Tsao, Heng-Kwong, E-mail: yjsheng@ntu.edu.tw, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical and Materials Engineering and Department of Physics, National Central University, Jhongli 320, Taiwan (China)

    2014-08-07

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n{sup ′}) motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n{sup ′}-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  15. Colloidosomes formed by nonpolar/polar/nonpolar nanoball amphiphiles.

    Science.gov (United States)

    Chang, Hung-Yu; Tu, Sheng-Hung; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-08-01

    Fullerene-based amphiphiles are able to form bilayer vesicles in aqueous solution. In this study, the self-assembly behavior of polymer-tethered nanoballs (NBs) with nonpolar/polar/nonpolar (n-p-n') motif in a selective solvent is investigated by dissipative particle dynamics. A model NB bears two hydrophobic polymeric arms (n'-part) tethered on an extremely hydrophobic NB (n-part) with hydrophilic patch (p-part) patterned on its surface. Dependent on the hydrophobicity and length of tethered arms, three types of aggregates are exhibited, including NB vesicle, core-shell micelle, and segmented-worm. NB vesicles are developed for a wide range of hydrophobic arm lengths. The presence of tethered arms perturbs the bilayer structure formed by NBs. The structural properties including the order parameter, membrane thickness, and area density of the inner leaflet decrease with increasing the arm length. These results indicate that for NBs with longer arms, the extent of interdigitation in the membrane rises so that the overcrowded arms in the inner corona are relaxed. The transport and mechanical properties are evaluated as well. As the arm length grows, the permeability increases significantly because the steric bulk of tethered arms loosens the packing of NBs. By contrast, the membrane tension decreases owing to the reduction of NB/solvent contacts by the polymer corona. Although fusion can reduce membrane tension, NB vesicles show strong resistance to fusion. Moreover, the size-dependent behavior observed in small liposomes is not significant for NB vesicles due to isotropic geometry of NB. Our simulation results are consistent with the experimental findings.

  16. A Research Module for the Organic Chemistry Laboratory: Multistep Synthesis of a Fluorous Dye Molecule.

    Science.gov (United States)

    Slade, Michael C; Raker, Jeffrey R; Kobilka, Brandon; Pohl, Nicola L B

    2014-01-14

    A multi-session research-like module has been developed for use in the undergraduate organic teaching laboratory curriculum. Students are tasked with planning and executing the synthesis of a novel fluorous dye molecule and using it to explore a fluorous affinity chromatography separation technique, which is the first implementation of this technique in a teaching laboratory. Key elements of the project include gradually introducing students to the use of the chemical literature to facilitate their searching, as well as deliberate constraints designed to force them to think critically about reaction design and optimization in organic chemistry. The project also introduces students to some advanced laboratory practices such as Schlenk techniques, degassing of reaction mixtures, affinity chromatography, and microwave-assisted chemistry. This provides students a teaching laboratory experience that closely mirrors authentic synthetic organic chemistry practice in laboratories throughout the world.

  17. A Research Module for the Organic Chemistry Laboratory: Multistep Synthesis of a Fluorous Dye Molecule

    Science.gov (United States)

    2014-01-01

    A multi-session research-like module has been developed for use in the undergraduate organic teaching laboratory curriculum. Students are tasked with planning and executing the synthesis of a novel fluorous dye molecule and using it to explore a fluorous affinity chromatography separation technique, which is the first implementation of this technique in a teaching laboratory. Key elements of the project include gradually introducing students to the use of the chemical literature to facilitate their searching, as well as deliberate constraints designed to force them to think critically about reaction design and optimization in organic chemistry. The project also introduces students to some advanced laboratory practices such as Schlenk techniques, degassing of reaction mixtures, affinity chromatography, and microwave-assisted chemistry. This provides students a teaching laboratory experience that closely mirrors authentic synthetic organic chemistry practice in laboratories throughout the world. PMID:24501431

  18. Hollow Nanospheres with Fluorous Interiors for Transport of Molecular Oxygen in Water

    KAUST Repository

    Vu, Khanh B.

    2016-08-11

    A dispersion system for saturated fluorocarbon (SFC) liquids based on permeable hollow nanospheres with fluorous interiors is described. The nanospheres are well dispersible in water and are capable of immediate uptake of SFCs. The nanosphere shells are gas-permeable and feature reactive functional groups for easy modification of the exterior. These features make the SFC-filled nanospheres promising vehicles for respiratory oxygen storage and transport. Uptake of molecular oxygen into nanosphere-stabilized SFC dispersions is demonstrated.

  19. More Fluorous Surface Modifier Makes it Less Oleophobic: Fluorinated-Siloxane Copolymer/PDMS Coatings

    Science.gov (United States)

    Zhang, Wei; Zheng, Ying; Orsini, Lorenzo; Morelli, Andrea; Galli, Giancarlo; Chiellini, Emo; Carpenter, Everett E.; Wynne, Kenneth J.

    2010-01-01

    A copolyacrylate with semifluorinated and polydimethylsiloxane side chains (D5-3) was used as a surface modifier for a condensation cured PDMS coating. The decyl fluorous group is represented by “D”; “5” is a 5 kDa silicone, and “3” the mole ratio of fluorous to silicone side chain. Wetting behavior was assessed by dynamic contact angle (DCA) analysis using isopropanol, which differentiates silicone and fluorous wetting behavior. Interestingly, a maximum in surface oleophobicity was found at low D5-3 concentration (0.4 wt%). Higher concentrations result in decreased oleophobicity reflected in decreased contact angles. To understand this unexpected observation, dynamic light scattering (DLS) studies were initiated on a model system consisting of hydroxyl-terminated PDMS (18 kDa) containing varying amounts of D5-3. DLS revealed D5-3 aggregation as a function of temperature and concentration. A model is proposed by which D5-3 surface concentration is depleted via phase separation favoring D5-3 aggregation at concentrations >0.4 wt%, that is, the CMC. This model suggests increasing aggregate / micelle concentrations at increased D5-3 concentration. Bulk morphologies studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) support this model by showing increased aggregate concentrations with increased D5-3 >0.4 wt%. PMID:20000339

  20. More fluorous surface modifier makes it less oleophobic: fluorinated siloxane copolymer/PDMS coatings.

    Science.gov (United States)

    Zhang, Wei; Zheng, Ying; Orsini, Lorenzo; Morelli, Andrea; Galli, Giancarlo; Chiellini, Emo; Carpenter, Everett E; Wynne, Kenneth J

    2010-04-20

    A copolyacrylate with semifluorinated and polydimethylsiloxane side chains (D5-3) was used as a surface modifier for a condensation-cured PDMS coating. The decyl fluorous group is represented by "D"; "5" is a 5 kDa silicone, and "3" is the mole ratio of fluorous to silicone side chains. Wetting behavior was assessed by dynamic contact angle (DCA) analysis using isopropanol, which differentiates silicone and fluorous wetting behavior. Interestingly, a maximum in surface oleophobicity was found at low D5-3 concentration (0.4 wt %). Higher concentrations result in decreased oleophobicity, as reflected in decreased contact angles. To understand this unexpected observation, dynamic light scattering (DLS) studies were initiated on a model system consisting of hydroxyl-terminated PDMS (18 kDa) containing varying amounts of D5-3. DLS revealed D5-3 aggregation to be a function of temperature and concentration. A model is proposed by which D5-3 surface concentration is depleted via phase separation favoring D5-3 aggregation at concentrations >0.4 wt %, that is, the cmc. This model suggests increasing aggregate/micelle concentrations at increased D5-3 concentration. Bulk morphologies studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) support this model by showing increased aggregate concentrations with increased D5-3 > 0.4 wt %.

  1. Fluorocarbon compatibilized gold-silica nanocomposites for recyclable regioselective hydroamination of alkynes in a fluorous biphasic system

    Science.gov (United States)

    Merican, Zulkifli; Vu, Bao Khanh; Solovyeva, Vera A.; Rodionov, Valentin O.; Khe, Cheng Seong; Rajalingam, Sokkalingam; Vasant, Pandian

    2016-11-01

    The synthesis and characterization of the mesoporous silica-supported gold (Au@mSiO2) nanoparticles compatibilized with the outer shelled superhydrophobic fluorous (F) "tails" was described. The concept of fluorous biphasic separation was applied in the recycling of the synthesized fluorous material during hydroamination reactions of various alkynes. In the presence of perfluoromethylcyclohexane and heptane as a biphasic liquid system, the F-Au@mSiO2 was found to be a highly active catalyst for hydroamination of various alkynes with anilines, and a near quantitative yield for an imine product and produced a relatively minimal formation of a corresponding hydrolyzed ketone by-product. If perfluoromethylcyclohexane and heptane was used as a biphasic solvent, hydroamination at a lower reaction temperature can also be realized leading to an improved recyclability and conversion.

  2. Direct tandem mass spectrometric analysis of amino acids in plasma using fluorous derivatization and monolithic solid-phase purification.

    Science.gov (United States)

    Tamashima, Erina; Hayama, Tadashi; Yoshida, Hideyuki; Imakyure, Osamu; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2015-11-10

    In this study, we developed a novel direct tandem mass spectrometric method for rapid and accurate analysis of amino acids utilizing a fluorous derivatization and purification technique. Amino acids were perfluoroalkylated with 2H,2H,3H,3H-perfluoroundecan-1-al in the presence of 2-picoline borane via reductive amination. The derivatives were purified by perfluoroalkyl-modified silica-based monolithic solid-phase extraction (monolithic F-SPE), and directly analyzed by tandem mass spectrometry using electrospray ionization without liquid chromatographic separation. The perfluoroalkyl derivatives could be sufficiently distinguished from non-fluorous compounds, i.e. the biological matrix, due to their fluorous interaction. Thus, rapid and accurate determination of amino acids was accomplished. The method was validated with human plasma samples and applied to the analysis of amino acids in the plasma of mice with maple syrup urine disease or phenylketonuria.

  3. Fluorous Mixture Synthesis of Four Stereoisomers of the C21–C40 Fragment of Tetrafibricin

    Science.gov (United States)

    Zhang, Kai

    2010-01-01

    Four stereoisomers of the C21–C40 fragment are synthesized in a single exercise with the aid of fluorous tagging to encode configurations at C37 and C33. After demixing and detagging, the isomers were found to have substantially identical 1H NMR spectra. However, there were some small but reliable differences in their 13C NMR spectra. PMID:20686632

  4. Birefringent non-polarizing thin film design

    Institute of Scientific and Technical Information of China (English)

    QI Hongji; HONG Ruijin; HE Hongbo; SHAO Jianda; FAN Zhengxiu

    2005-01-01

    In this paper, 2×2 characteristic matrices of uniaxially anisotropic thin film for extraordinary and ordinary wave are deduced at oblique incidence. Furthermore, the reflectance and transmittance of thin films are calculated separately for two polarizations, which provide a new concept for designing non-polarizing thin films at oblique incidence. Besides, using the multilayer birefringent thin films, non-polarizing designs, such as beam splitter thin film at single wavelength, edge filter and antireflection thin film over visible spectral region are obtained at oblique incidence.

  5. Development of fluorous lipid-based nanobubbles for efficiently containing perfluoropropane.

    Science.gov (United States)

    Oda, Yusuke; Suzuki, Ryo; Mori, Tatsuya; Takahashi, Hideyo; Natsugari, Hideaki; Omata, Daiki; Unga, Johan; Uruga, Hitoshi; Sugii, Mutsumi; Kawakami, Shigeru; Higuchi, Yuriko; Yamashita, Fumiyoshi; Hashida, Mitsuru; Maruyama, Kazuo

    2015-06-20

    Nano-/microbubbles are expected not only to function as ultrasound contrast agents but also as ultrasound-triggered enhancers in gene and drug delivery. Notably, nanobubbles have the ability to pass through tumor vasculature and achieve passive tumor targeting. Thus, nanobubbles would be an attractive tool for use as ultrasound-mediated cancer theranostics. However, the amounts of gas carried by nanobubbles are generally lower than those carried by microbubbles because nanobubbles have inherently smaller volumes. In order to reduce the injection volume and to increase echogenicity, it is important to develop nanobubbles with higher gas content. In this study, we prepared 5 kinds of fluoro-lipids and used these reagents as surfactants to generate "Bubble liposomes", that is, liposomes that encapsulate nanobubbles such that the lipids serve as stabilizers between the fluorous gas and water phases. Bubble liposome containing 1-stearoyl-2-(18,18-difluoro)stearoyl-sn-glycero-3-phosphocholine carried 2-fold higher amounts of C3F8 compared to unmodified Bubble liposome. The modified Bubble liposome also exhibited increased echogenicity by ultrasonography. These results demonstrated that the inclusion of fluoro-lipid is a promising tool for generating nanobubbles with increased efficiency of fluorous gas carrier.

  6. Synthesis of a series of maltotriose phosphates with an evaluation of the utility of a fluorous phosphate protecting group.

    Science.gov (United States)

    Liu, Lin; Pohl, Nicola L B

    2013-03-22

    A series of methyl maltotrioside phosphates were synthesized for application in the determination of the actual molecular substrate of the Lafora enzyme involved in Lafora disease. Several different synthetic routes were applied for the successful synthesis of six methyl maltotrioside phosphate regioisomers. The utility of a new fluorous phosphate protecting group was also evaluated, but its utility was found to be limited in this particular late stage introduction.

  7. Controlling Nonspecific Protein Adsorption in a Plug-Based Microfluidic System by Controlling Interfacial Chemistry Using Fluorous-Phase Surfactants

    OpenAIRE

    Roach, L. Spencer; Song, Helen; Ismagilov, Rustem F.

    2005-01-01

    Control of surface chemistry and protein adsorption is important for using microfluidic devices for biochemical analysis and high-throughput screening assays. This paper describes the control of protein adsorption at the liquid-liquid interface in a plug-based microfluidic system. The microfluidic system uses multiphase flows of immiscible fluorous and aqueous fluids to form plugs, which are aqueous droplets that are completely surrounded by fluorocarbon oil and do not come into direct contac...

  8. Modification of fluorous substrates with oligo(ethylene glycol) via "click" chemistry for long-term resistance of cell adhesion.

    Science.gov (United States)

    Contreras-Caceres, Rafael; Santos, Catherine M; Li, Siheng; Kumar, Amit; Zhu, Zhiling; Kolar, Satya S; Casado-Rodriguez, Miguel A; Huang, Yongkai; McDermott, Alison; Lopez-Romero, Juan Manuel; Cai, Chengzhi

    2015-11-15

    In this work perfluorinated substrates fabricated from SiO2 glass slides are modified with oligo(ethylene glycol) (OEG) units for long-term resistance of cell adhesion purposes, based on fluorous interactions and click chemistry. Specifically, fluorous substrates, prepared by treatment of glass slides with 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane (FAS17), were coated with ethynyl-OEG-C8F17, followed by covalent attachment of an azido-OEG via copper-catalyzed azide-alkyne cycloaddition (CuAAC) "click" reaction. We demonstrate that the resultant surface avoid fibrinogen adsorption and resisted cell adhesion for over 14days. X-ray photoemission spectroscopy (XPS) analysis and contact angle goniometry measurements confirm the presence of the OEG molecules on the fluorous substrates. Bright field optical images show total absence of 3T3 fibroblast cells on the OEG modified fluorinated substrate for 1 and 5days, and a remarkably decrease of cell adhesion at 14days.

  9. Fluorous Analogue of Chloramine-T: Preparation, X-ray Structure Determination, and Use as an Oxidant for Radioiodination and s-Tetrazine Synthesis.

    Science.gov (United States)

    Dzandzi, James P K; Beckford Vera, Denis R; Genady, Afaf R; Albu, Silvia A; Eltringham-Smith, Louise J; Capretta, Alfredo; Sheffield, William P; Valliant, John F

    2015-07-17

    A fluorous oxidant that can be used to introduce radioiodine into small molecules and proteins and generate iodinated tetrazines for bioorthogonal chemistry has been developed. The oxidant was prepared in 87% overall yield by combining a fluorous amine with tosyl chloride, followed by chlorination using aqueous sodium hypochlorite. A crystal structure of the oxidant, which is a fluorous analogue of chloramine-T, was obtained. The compound was shown to be stable for 7 days in EtOH and for longer than three months as a solid. The oxidant was effective at promoting the labeling of arylstannanes using [(125)I]NaI, where products were isolated in high specific activity in yields ranging from 46% to 86%. Similarly, iodinated biologically active proteins (e.g., thrombin) were successfully produced, as well as a radioiodinated tetrazine, through a concomitant oxidation-halodemetalation reaction. Because of its fluorous nature, unreacted oxidant and associated reaction byproducts can be removed quantitatively from reaction mixtures by passing solutions through fluorous solid phase extraction cartridges. This feature enables rapid and facile purification, which is critical when working with radionuclides and is similarly beneficial for general synthetic applications.

  10. Synthesis and properties of chemiluminescent acridinium ester labels with fluorous tags.

    Science.gov (United States)

    Natrajan, Anand; Wen, David; Sharpe, David

    2014-06-21

    Acridinium dimethylphenyl esters are highly sensitive chemiluminescent labels that are used in clinical diagnostics. Light emission from these labels is triggered with alkaline peroxide in the presence of the cationic surfactant cetyltrimethylammonium chloride (CTAC). CTAC compresses emission times of these labels to ester chemiluminescence (light yield) is quite sensitive to the polarity of the micellar interface. In the current study, we report the synthesis of new acridinium ester labels with fluorous tags of varying fluorine content and their chemiluminescence in the presence of cationic micelles of CTAC, anionic micelles of sodium perfluorooctanoate (SPFO) as well as mixed micelles of CTAC and SPFO. These studies indicate that in the presence of the mixed micelle system of CTAC and SPFO and at low mole fractions of SPFO, polarity of the mixed micelle interface is lower than that of CTAC leading to a greater enhancement of chemiluminescence for both fluorinated acridinium esters as well as a structurally analogous but non-fluorinated acridinium ester. Chemiluminescence stability of the fluorinated acridinium esters was either comparable to or better than the stability of the non-fluorinated acridinium ester. Non-specific binding to paramagnetic microparticles was higher for fluorinated acridinium esters requiring a surfactant wash to reduce their non-specific binding to the same extent as that observed for the non-fluorinated acridinium ester.

  11. Synthesis of diverse dihydropyrimidine-related scaffolds by fluorous benzaldehyde-based Biginelli reaction and post-condensation modifications

    Directory of Open Access Journals (Sweden)

    Bruno Piqani

    2011-09-01

    Full Text Available Dihydropyrimidinones and dihydropyrimidinethiones generated from the Biginelli reactions of perfluorooctanesulfonyl-attached benzaldehydes are used as common intermediates for post-condensation modifications such as cycloaddition, Liebeskind–Srogl reaction and Suzuki coupling to form biaryl-substituted dihydropyrimidinone, dihydropyrimidine, and thiazolopyrimidine compounds. The high efficiency of the diversity-oriented synthesis is achieved by conducting a multicomponent reaction for improved atom economy, under microwave heating for fast reaction, and with fluorous solid-phase extractions (F-SPE for ease of purification.

  12. EDITORIAL: Non-polar and semipolar nitride semiconductors Non-polar and semipolar nitride semiconductors

    Science.gov (United States)

    Han, Jung; Kneissl, Michael

    2012-02-01

    Throughout the history of group-III-nitride materials and devices, scientific breakthroughs and technological advances have gone hand-in-hand. In the late 1980s and early 1990s, the discovery of the nucleation of smooth (0001) GaN films on c-plane sapphire and the activation of p-dopants in GaN led very quickly to the realization of high-brightness blue and green LEDs, followed by the first demonstration of GaN-based violet laser diodes in the mid 1990s. Today, blue InGaN LEDs boast record external quantum efficiencies exceeding 80% and the emission wavelength of the InGaN-based laser diode has been pushed into the green spectral range. Although these tremenduous advances have already spurred multi-billion dollar industries, there are still a number of scientific questions and technological issues that are unanswered. One key challenge is related to the polar nature of the III-nitride wurtzite crystal. Until a decade ago all research activities had almost exclusively concentrated on (0001)-oriented polar GaN layers and heterostructures. Although the device characteristics seem excellent, the strong polarization fields at GaN heterointerfaces can lead to a significant deterioration of the device performance. Triggered by the first demonstration non-polar GaN quantum wells grown on LiAlO2 by Waltereit and colleagues in 2000, impressive advances in the area of non-polar and semipolar nitride semiconductors and devices have been achieved. Today, a large variety of heterostructures free of polarization fields and exhibiting exceptional electronic and optical properties have been demonstrated, and the fundamental understanding of polar, semipolar and non-polar nitrides has made significant leaps forward. The contributions in this Semiconductor Science and Technology special issue on non-polar and semipolar nitride semiconductors provide an impressive and up-to-date cross-section of all areas of research and device physics in this field. The articles cover a wide range of

  13. Towards Extending Solar Cell Lifetimes: Addition of a Fluorous Cation to Triple Cation-Based Perovskite Films.

    Science.gov (United States)

    Salado, Manuel; Fernández, M Asunción; Holgado, Juan P; Kazim, Samrana; Nazeeruddin, Mohammad Khaja; Dyson, Paul J; Ahmad, Shahzada

    2017-07-25

    Organohalide perovskites have emerged as highly promising replacements for thin-film solar cells. However, their poor stability under ambient conditions remains problematic, hindering commercial exploitation. The addition of a fluorous-functionalized imidazolium cation during the preparation of a highly stable cesium-based mixed perovskite material Cs0.05 (MA0.15 FA0.85 )0.95 Pb(I0.85 Br0.15 )3 (MA=methylammonium; FA=formamidinium) has been shown to influence its stability. The resulting materials, which vary according to the amount of the fluorous-functionalized imidazolium cation present during fabrication, display a prolonged tolerance to atmospheric humidity (>100 days) along with power conversion efficiencies exceeding 16 %. This work provides a general route that can be implemented in a variety of perovskites and highlights a promising way to increase perovskite solar cell stability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A hybrid fluorous monolithic capillary column with integrated nanoelectrospray ionization emitter for determination of perfluoroalkyl acids by nano-liquid chromatography-nanoelectrospray ionization-mass spectrometry/mass spectrometry.

    Science.gov (United States)

    Zhang, Haiyang; Ou, Junjie; Wei, Yinmao; Wang, Hongwei; Liu, Zhongshan; Zou, Hanfa

    2016-04-01

    A hybrid fluorous monolithic column was simply prepared via photo-initiated free radical polymerization of an acrylopropyl polyhedral oligomeric silsesquioxane (acryl-POSS) and a perfluorous monomer (2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate) in UV-transparent fused-silica capillaries within 5min. The physical characterization of hybrid fluorous monolith, including scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, mercury intrusion porosimetry (MIP) and nitrogen adsorption/desorption measurement was performed. Chromatographic performance was also evaluated by capillary liquid chromatography (cLC). Due to the fluorous-fluorous interaction between fluorous monolith and analytes, fluorobenzenes could well be separated, and the column efficiencies reached 86,600-92,500plates/m at the velocity of 0.87mm/s for alkylbenzenes and 51,900-76,000plates/m at the velocity of 1.10mm/s for fluorobenzenes. Meanwhile, an approach to integrate nanoelectrospray ionization (ESI) emitter with hybrid fluorous monolithic column was developed for quantitative determination of perfluoroalkyl acids by nanoHPLC-ESI-MS/MS. The integration design could minimize extracolumn volume, thus excluding undesirable peak broadening and improving separation performance.

  15. Fluorinated carbon tag derivatization combined with fluorous solid-phase extraction: a new method for the highly sensitive and selective mass spectrometric analysis of glycans.

    Science.gov (United States)

    Li, Lulu; Jiao, Jing; Cai, Yan; Zhang, Ying; Lu, Haojie

    2015-01-01

    The sensitive and specific detection of glycans via mass spectrometry (MS) remains a significant challenge due to their low abundance in complex biological mixtures, inherent lack of hydrophobicity, and suppression by other, more abundant biological molecules (proteins/peptides) or contaminants. A new strategy for the sensitive and selective MS analysis of glycans based on fluorous chemistry is reported. Glycan reducing ends were derivatized with a hydrophobic fluorinated carbon tag, increasing glycan ionization efficiency during MS by more than an order of magnitude. More importantly, the fluorinated carbon tag enabled efficient fluorous solid-phase extraction (FSPE) to specifically enrich the glycans from contaminated solutions and protein mixtures. Finally, we successfully analyzed the N-glycome in human serum using this new method.

  16. Long-Wavelength Phonon Scattering in Nonpolar Semiconductors

    DEFF Research Database (Denmark)

    Lawætz, Peter

    1969-01-01

    The long-wavelength acoustic- and optical-phonon scattering of carriers in nonpolar semiconductors is considered from a general point of view. The deformation-potential approximation is defined and it is shown that long-range electrostatic forces give a nontrivial correction to the scattering. Fo...

  17. The role of solvent cohesion in nonpolar solvation

    NARCIS (Netherlands)

    Otto, Sijbren

    2013-01-01

    Understanding hydrophobic interactions requires a molecular-level picture of how water molecules adjust to the introduction of a nonpolar solute. New insights into the latter process are derived from the observation that the Gibbs energies of solvation of the noble gases and linear alkanes by a wide

  18. Lipophilic polyelectrolyte gels as super-absorbent polymers for nonpolar organic solvents.

    Science.gov (United States)

    Ono, Toshikazu; Sugimoto, Takahiro; Shinkai, Seiji; Sada, Kazuki

    2007-06-01

    Polyelectrolyte gels that are known as super-absorbent polymers swell and absorb water up to several hundred times their dried weights and have become ubiquitous and indispensable materials in many applications. Their superior swelling abilities originate from the electrostatic repulsion between the charges on the polymer chains and the osmotic imbalance between the interior and exterior of the gels. However, no super-absorbent polymers for volatile organic compounds (VOCs), and especially for nonpolar organic solvents (epsilonpolymer networks. This expands the potential of polyelectrolytes that have been used only in aqueous solutions or highly polar solvents, and provides soft materials that swell in a variety of media. These materials could find applications as protective barriers for VOCs spilled in the environment and as absorbents for waste oil.

  19. Fluctuation capture in non-polar gases and liquids

    CERN Document Server

    Cocks, D G

    2016-01-01

    We present a new model to identify natural fluctuations in fluids, allowing us to describe localization phenomena in the transport of electrons, positrons and positronium through non-polar fluids. The theory contains no free parameters and allows for the calculation of capture cross sections $\\sigma_{cap}(\\epsilon)$ of light-particles in any non-polar fluid, required for non-equilibrium transport simulations. We postulate that localization occurs through large shallow traps before stable bound states are formed. Our results allow us to explain most of the experimental observations of changes in mobility and annihilation rates in the noble gases and liquids as well as make predictions for future experiments. Quantities which are currently inaccessible to experiment, such as positron mobilities, can be obtained from our theory. Unlike other theoretical approaches to localization, the outputs of our theory can be applied in non-equilibrium transport simulations and an extension to the determination of waiting ti...

  20. Nanoencapsulation of Fullerenes in Organic Structures with Nonpolar Cavities

    Science.gov (United States)

    Murthy, C. N.

    2005-01-01

    The formation of supramolecular structures, assemblies, and arrays held together by weak intermolecular interactions and non-covalent binding mimicking natural processes has been used in applications being anticipated in nanotechnology, biotechnology and the emerging field of nanomedicine. Encapsulation of C60 fullerene by cyclic molecules like cyclodextrins and calixarenes has potential for a number of applications. Similarly, biomolecules like lysozyme also have been shown to encapsulate C60 fullerene. This poster article reports the recent trends and the results obtained in the nanoencapsulation of fullerenes by biomolecules containing nonpolar cavities. Lysozyme was chosen as the model biomolecule and it was observed that there is no covalent bond formed between the bimolecule and the C60 fullerene. This was confirmed from fluorescence energy transfer studies. UV Vis studies further supported this observation that it is possible to selectively remove the C60 fullerene from the nonpolar cavity. This behavior has potential in biomedical applications

  1. Nanoencapsulation of Fullerenes in Organic Structures with Nonpolar Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, C. N. [M.S. University of Baroda, Applied Chemistry Department, Faculty of Technology and Engineering (India)

    2005-01-15

    The formation of supramolecular structures, assemblies, and arrays held together by weak intermolecular interactions and non-covalent binding mimicking natural processes has been used in applications being anticipated in nanotechnology, biotechnology and the emerging field of nanomedicine. Encapsulation of C{sub 60} fullerene by cyclic molecules like cyclodextrins and calixarenes has potential for a number of applications. Similarly, biomolecules like lysozyme also have been shown to encapsulate C{sub 60} fullerene. This poster article reports the recent trends and the results obtained in the nanoencapsulation of fullerenes by biomolecules containing nonpolar cavities. Lysozyme was chosen as the model biomolecule and it was observed that there is no covalent bond formed between the bimolecule and the C{sub 60} fullerene. This was confirmed from fluorescence energy transfer studies. UV-Vis studies further supported this observation that it is possible to selectively remove the C{sub 60} fullerene from the nonpolar cavity. This behavior has potential in biomedical applications

  2. Thermodiffusion in binary and ternary nonpolar hydrocarbon + alcohol mixtures

    Science.gov (United States)

    Eslamian, Morteza; Saghir, M. Ziad

    2012-12-01

    Thermodiffusion in complex mixtures, such as associating, molten metal, and polymer mixtures is difficult to model usually owing to the occurrence of a sign change in the thermodiffusion coefficient when the mixture concentration and temperature change. A mixture comprised of a nonpolar hydrocarbon and an alcohol is a complex and highly non-ideal mixture. In this paper an existing binary non-equilibrium thermodynamics model (Eslamian and Saghir, Physical Review E 80, 061201, 2009) developed for aqueous mixtures of alcohols is examined against the experimental data of binary nonpolar hydrocarbon and alcohol mixtures. For ternary mixtures, non-equilibrium thermodynamic expressions developed by the authors for aqueous mixtures of alcohols (Eslamian and Saghir, Canadian Journal of Chemical Engineering, DOI 10.1002/cjce.20581) is used to predict thermodiffusion coefficients of ternary nonpolar hydrocarbon and alcohol mixtures. The rationale behind the sign change is elucidated and attributed to an anomalous change in the molecular structure and therefore viscosity of such mixtures. Model predictions of thermodiffusion coefficients of binary mixtures predict a sign change consistent with the experimental data although the model is still too primitive to capture all structural complexities. For instance, in the methanol-benzene mixture where the model predictions are poorest, the viscosity data show that when concentration varies, the mixture's molecular structure experiences a severe change twice, the first major change leading to a maximum in the thermodiffusion coefficient, whereas the second change causes a sign change.

  3. Solvent density mode instability in non-polar solutions

    Indian Academy of Sciences (India)

    Susmita Kar; Ranjit Biswas; J Chakrabarti

    2008-08-01

    We analyse the origin of the multiple long time scales associated with the long time decay observed in non-polar solvation dynamics by linear stability analysis of solvent density modes where the effects of compressibility and solvent structure are systematically incorporated. The coupling of the solute–solvent interactions at both ground and excited states of the solute with the compressibility and solvent structure is found to have important effects on the time scales. The present theory suggests that the relatively longer time constant is controlled by the solvent compressibility, while the solvent structure at the nearest-neighbour length scale dominates the shorter time constant.

  4. Photonic Crystal Polarizing and Non-Polarizing Beam Splitters

    Institute of Scientific and Technical Information of China (English)

    GUAN Chun-Ying; SHI Jin-Hui; YUAN Li-Bo

    2008-01-01

    A polarizing beam splitter(PBS)and a non-polarizing beam splitter(NPBS)based on a photonic crystal(PC)directional coupler are demonstrated.The photonic crystal directional coupler consists of a hexagonal lattice of dielectric pillars in air and has a complete photonic band gap.The photonic band structure and the band gap map are calculated using the plane wave expansion(PWE)method.The splitting properties of the splitter are investigated numerically using the finite difference time domain(FDTD)method.

  5. Highly selective detection of silver in the low ppt range with ion-selective electrodes based on ionophore-doped fluorous membranes.

    Science.gov (United States)

    Lai, Chun-Ze; Fierke, Melissa A; Corrêa da Costa, Rosenildo; Gladysz, John A; Stein, Andreas; Bühlmann, Philippe

    2010-09-15

    Ionophore-doped sensing membranes exhibit greater selectivities and wider measuring ranges if their membrane matrixes are noncoordinating and solvate interfering ions poorly. This is particularly true for fluorous phases, which are the least polar and polarizable condensed phases known. In this work, fluorous membrane matrixes were used to prepare silver ion-selective electrodes (ISEs). Sensing membranes composed of perfluoroperhydrophenanthrene, sodium tetrakis[3,5-bis(perfluorohexyl) phenyl]borate, and one of four fluorophilic Ag(+)-selective ionophores with one or two thioether groups were investigated. All electrodes exhibited Nernstian responses to Ag(+) in a wide range of concentrations. Their selectivities for Ag(+) over interfering ions were found to depend on host preorganization and the length of the -(CH(2))(n)- spacers separating the coordinating thioether group from the strongly electron withdrawing perfluoroalkyl groups. ISEs based on the most selective of the four ionophores, that is, 1,3-bis(perfluorodecylethylthiomethyl)benzene, provided much higher selectivities for Ag(+) over many alkaline and heavy metal ions than most Ag(+) ISEs reported in the literature (e.g., log K(Ag,J)(pot) for K(+), -11.6; Pb(2+), -10.2; Cu(2+), -13.0; Cd(2+), -13.2). Moreover, the use of this ionophore with a linear perfluorooligoether as membrane matrix and solid contacts consisting of three-dimensionally ordered macroporous (3DOM) carbon resulted in a detection limit for Ag(+) of 4.1 ppt (3.8 × 10(-1)1 M).

  6. Electrophoretic Retardation of Colloidal Particles in Nonpolar Liquids

    Directory of Open Access Journals (Sweden)

    Filip Strubbe

    2013-04-01

    Full Text Available We have measured the electrophoretic mobility of single, optically trapped colloidal particles, while gradually depleting the co-ions and counterions in the liquid around the particle by applying a dc voltage. This is achieved in a nonpolar liquid, where charged reverse micelles act as co-ions and counterions. By increasing the dc voltage, the mobility first increases when the concentrations of co-ions and counterions near the particle start to decrease. At sufficiently high dc voltage (around 2 V, the mobility reaches a saturation value when the co-ions and counterions are fully separated. The increase in mobility is larger when the equilibrium ionic strength is higher. The dependence of the experimental data on the equilibrium ionic strength and on the applied voltage is in good agreement with the standard theory of electrophoretic retardation, assuming that the bare particle charge remains constant. This method is useful for studying the electrophoretic retardation effect and charging mechanisms for nonpolar colloids, and it sheds light on previously unexplained particle acceleration in electronic ink devices.

  7. Observation of water dangling OH bonds around dissolved nonpolar groups.

    Science.gov (United States)

    Perera, P N; Fega, K R; Lawrence, C; Sundstrom, E J; Tomlinson-Phillips, J; Ben-Amotz, Dor

    2009-07-28

    We report the experimental observation of water dangling OH bonds in the hydration shells around dissolved nonpolar (hydrocarbon) groups. The results are obtained by combining vibrational (Raman) spectroscopy and multivariate curve resolution (MCR), to reveal a high-frequency OH stretch peak arising from the hydration shell around nonpolar (hydrocarbon) solute groups. The frequency and width of the observed peak is similar to that of dangling OH bonds previously detected at macroscopic air-water and oil-water interfaces. The area of the observed peak is used to quantify the number of water dangling bonds around hydrocarbon chains of different length. Molecular dynamics simulation of the vibrational spectra of water molecules in the hydration shell around neopentane and benzene reveals high-frequency OH features that closely resemble the experimentally observed dangling OH vibrational bands around neopentyl alcohol and benzyl alcohol. The red-shift of approximately 50 cm(-1) induced by aromatic solutes is similar to that previously observed upon formation of a pi-H bond (in low-temperature benzene-water clusters).

  8. Ion Sensor Based on Fluorous Liquid Phase Sensing Membrane with High Selectivity%基于高选择性氟液相传感膜的离子传感器

    Institute of Scientific and Technical Information of China (English)

    黄美荣; 丁永波; 施凤英; 李新贵

    2012-01-01

    本文基于国外最新研究工作,系统总结了电位型传感器中的一种新型传感膜——氟液相传感膜。对构成氟液相传感膜的所有组分:氟溶剂、溶解在氟溶剂中的亲氟离子交换剂和亲氟离子载体以及对氟溶剂起支撑作用的惰性微孔支撑膜等进行了全面归纳,重点讨论了这4种因素对传感器性能的影响。指出目前使用的亲氟离子交换剂分子和亲氟离子载体分子均含有2—8根链长为6—10的全氟碳链。氟液相传感膜具有优于传统PVC膜的检测下限,其中通过三维有序大孔碳以固体接触方式构建的氟液相传感膜电位传感器对Ag+的探测下限可达3.8×10-11mol/L。氟液相传感膜还具有十分出色的选择性,无任何离子载体的空白氟液相传感膜的选择系数对数值log Kpi,oJt的跨越宽度达16—18,比无载体的PVC膜宽8个数量级。这类全新的氟液相传感膜构建的电位型离子传感器将以其独特的优势在环境监测、食品卫生,尤其是在医疗诊断、生物物质检测中展示出不可替代的作用。%New fluorous liquid sensing membranes for the fabrication of potentiometric sensors are systematically summarized. Fluorous solvents, fluorophilic ion-exchangers and fluorophilic ionophores doped in the fluorous solvents, as well as inert fluorous porous supports, are reviewed thoroughly. The influence of the four factors on the performance of potentiometric sensors is concentrated. It is pointed out that both the fluorophilic ion- exchangers and ionophores used so far contain 2--8 perfluoroalkyl chains which are composed of 6--10 carbon atoms in each chain. Such a fluorous liquid phase sensing membrane possesses a superior lower detection limit compared with conventional poly(vinyl chloride)(PVC) membranes. For Ag( I ) potentiometric sensor based on the fluorous liquid membrane with solid contact through three-dimensionally ordered macroporous (3DOM) carbon, the lower

  9. Coherent Control of Vibrational State Population in a Nonpolar Molecule

    CERN Document Server

    Picón, A; Jaron-Becker, A; Becker, A; 10.1103/PhysRevA.83.023412

    2011-01-01

    A coherent control scheme for the population distribution in the vibrational states of nonpolar molecules is proposed. Our theoretical analysis and results of numerical simulations for the interaction of the hydrogen molecular ion in its electronic ground state with an infrared laser pulse reveal a selective two-photon transition between the vibrational states via a coupling with the first excited dissociative state. We demonstrate that for a given temporal intensity profile the population transfer between vibrational states, or a superposition of vibrational states, can be made complete for a single chirped pulse or a train of chirped pulses, which accounts for the accumulated phase difference due to the AC Stark effect. Effects of a spatial intensity (or, focal) averaging are discussed.

  10. Polarity inversion in polar-nonpolar-polar heterostructures.

    Science.gov (United States)

    Cho, S; Youn, S J; Kim, Y; DiVenere, A; Wong, G K; Freeman, A J; Ketterson, J B

    2001-09-17

    We have observed an epilayer-thickness-dependent polarity inversion for the growth of CdTe on Sb(Bi)/CdTe(111)B. For films with Sb(Bi) thicknesses of less than 40 A (15 A), the CdTe layer shows a B (Te-terminated) face, but it switches to an A (Cd-terminated) face for thicker layers. On the other hand, a CdTe layer grown on Bi(Sb)/CdTe(111)A always shows the A face regardless of Sb or Bi layer thicknesses. In order to address the observations we have performed ab initio calculations, which suggest that the polarity of a polar material on a nonpolar one results from the binding energy difference between the two possible surface configurations.

  11. Remarks on energetic conditions for positronium formation in non-polar solids. Coupled Dipole Method application

    CERN Document Server

    Pietrow, Marek

    2015-01-01

    A numerical program calculating an energy of a positron or (and) an electron near the free volume in solid n-alkanes has been build. The theory of interaction of e+ or (and) e- with this non-polar media based on polarizability has been introduced. The energy of the e+ -- e- pair in the bulk was compared to that calculated when the pair forms a positronium (Ps) inside the free volume. The calculations are based on the Coupled Dipole Method and the dipole-dipole interaction energy for induced dipoles is taken into account. Furthermore, a correction of a local permittivity for the e+ -- e- interaction is calculated taking into account the non-isotropic medium between them. The method is a step toward more accurate calculations of energetic conditions during the Ps formation in matter. The possibility of emission of the excess energy of the Ps formation as electromagnetic radiation is discussed. It is argued that if this radiation is observed, it can be used as a new spectroscopic tool providing information about...

  12. A "shortcut" Mosher ester method to assign configurations of stereocenters in nearly symmetric environments. Fluorous mixture synthesis and structure assignment of petrocortyne A.

    Science.gov (United States)

    Curran, Dennis P; Sui, Bin

    2009-04-22

    A "shortcut" of the advanced Mosher rule for use in assigning stereocenters in molecules with elements of local symmetry is proposed. A single Mosher ester is made, and the chemical shifts of pairs of resonances related by local symmetry are subtracted from each other (rather than from analogous resonances in the isomeric Mosher ester) to provide the configuration. Fluorous mixture synthesis is used to make a stereoisomer library of the four isomers of petrocortyne A. These samples and the derived Mosher esters are used to assign the (3S,14S) configuration to petrocortyne A and to validate both the standard and shortcut Mosher methods for use in the petrocortyne family of dialkynyl carbinols.

  13. Fluorous Biphase System of C9F18 and Its Use in Esterification%全氟壬烯氟两相体系及其在酯化反应中的应用

    Institute of Scientific and Technical Information of China (English)

    史鸿鑫; 项菊萍; 武宏科

    2007-01-01

    Some apolar organic solvents is miscible with perfluorous nonene to form fluorous biphase systems.Perfluorous nonene could be used as a green solvent in equimolar esterification of carboxylic acids with alcohols without removal of water or ester formed. Perfluorous nonene made the esterification equilibrium to move right and the yields of esterification to enhance in different degrees as compared with that in the absence of perfiuorous nonene. After esterification perfluorous nonene is easy to be recovered and recycled.

  14. Current Development in the Heterogenization of Homogeneous Catalysis——Fluorous Biphase System%均相催化多相化新进展——氟两相体系

    Institute of Scientific and Technical Information of China (English)

    鲁福身; 晁建平; 杨春育

    2001-01-01

    The FBS (fluorous biphase system) makes homogeneous catalysis and heterogeneous separation possible and easy to separate the catalysts dissolved in PFC (perfluorocarbons). Current developments in the chemistry of FBS and fluorous syntheses, including fluorous soluble ligands, catalysts and reagents are summarized. Numerous applications of FBS in hydroformylation, hydroboration and other organic reactions are also discussed.%氟两相体系实现了均相催化多相化,可以方便地分离溶解在PFC中的催化剂。本文综述了氟两相体系及氟合成领域,包括氟溶配体、催化剂和反应物等方面的最新进展。对氟两相体系在烯烃的氢甲酰化反应、硼氢化反应以及其它有机反应中的广泛应用作了讨论。

  15. Density and Phase State of a Confined Nonpolar Fluid

    Science.gov (United States)

    Kienle, Daniel F.; Kuhl, Tonya L.

    2016-07-01

    Measurements of the mean refractive index of a spherelike nonpolar fluid, octamethytetracylclosiloxane (OMCTS), confined between mica sheets, demonstrate direct and conclusive experimental evidence of the absence of a first-order liquid-to-solid phase transition in the fluid when confined, which has been suggested to occur from previous experimental and simulation results. The results also show that the density remains constant throughout confinement, and that the fluid is incompressible. This, along with the observation of very large increases (many orders of magnitude) in viscosity during confinement from the literature, demonstrate that the molecular motion is limited by the confining wall and not the molecular packing. In addition, the recently developed refractive index profile correction method, which enables the structural perturbation inherent at a solid-liquid interface and that of a liquid in confinement to be determined independently, was used to show that there was no measurable excess or depleted mass of OMCTS near the mica surface in bulk films or confined films of only two molecular layers.

  16. Design of non-polarizing thin film edge filters

    Institute of Scientific and Technical Information of China (English)

    GU Pei-fu; ZHENG Zhen-rong

    2006-01-01

    The separation between s- and p-polarization components invariably affects thin film edge filters used for tilted incidence and is a difficult problem for many applications, especially for optical communication. This paper presents a novel design method to obtain edge filters with non-polarization at incidence angle of 45°. The polarization separation at 50% transmittance for a long-wave-pass filter and a short-wave-pass filter is 0.3 nm and 0.1 nm respectively. The design method is based on a broadband Fabry-Perot thin-film interference filter in which the higher or lower interference band at both sides of the main transmittance peak can be used for initial design of long-wave-pass filter or short-wave-pass filter and then can be refined to reduce the transmittance ripples. The spacer 2H2L2H or 2L2H2L of the filter is usually taken. Moreover, the method for expanding the bandwidth of rejection and transmission is explained. The bandwidth of 200 nm for both rejection region and transmission band is obtained at wavelength 1550 nm. In this way, the long-wave-pass and short-wave-pass edge filters with zero separation between two polarization components can easily be fabricated.

  17. Metabolic Activation of Nonpolar Sediment Extracts Results in enhanced Thyroid Hormone Disrupting Potency

    NARCIS (Netherlands)

    Montano, M.; Weiss, J.; Hoffmann, L.; Gutleb, A.C.; Murk, A.J.

    2013-01-01

    Traditional sediment risk assessment predominantly considers the hazard derived from legacy contaminants that are present in nonpolar sediment extracts, such as polychlorinated biphenyls (PCBs), dioxins, furans (PCDD/Fs), and polyaromatic hydrocarbons (PAHs). Although in vivo experiments with these

  18. Adsorption of polar, nonpolar, and substituted aromatics to colloidal graphene oxide nanoparticles

    NARCIS (Netherlands)

    Wang, Fang; Haftka, Joris J H; Sinnige, Theo L.; Hermens, Joop L M; Chen, Wei

    2014-01-01

    We conducted batch adsorption experiments to understand the adsorptive properties of colloidal graphene oxide nanoparticles (GONPs) for a range of environmentally relevant aromatics and substituted aromatics, including model nonpolar compounds (pyrene, phenanthrene, naphthalene, and 1,3-dichlorobenz

  19. Acousto-optic modulation and deflection of terahertz electromagnetic radiation in nonpolar liquids

    Science.gov (United States)

    Nikitin, P. A.; Voloshinov, V. B.; Gerasimov, V. V.; Knyazev, B. A.

    2017-07-01

    The results of a series of experiments on controlled deflection of electromagnetic radiation of a free-electron laser upon diffraction by an acoustic wave in nonpolar liquids are presented. Acoustic and optical properties of liquids that are transparent in the terahertz range are discussed. It is demonstrated that nonpolar liquids may turn out to be a more efficient acousto-optic interaction medium than dielectric crystals or semiconductors.

  20. The influence of non-polar lipids on tear film dynamics

    KAUST Repository

    Bruna, M.

    2014-04-04

    © 2014 Cambridge University Press. In this paper we examine the effect that physiological non-polar lipids, residing on the surface of an aqueous tear film, have on the film evolution. In our model we track the evolution of the thickness of the non-polar lipid layer, the thickness of the aqueous layer and the concentration of polar lipids which reside at the interface between the two. We also utilise a force balance in the non-polar lipid layer in order to determine its velocity. We show how to obtain previous models in the literature from our model by making particular choices of the parameters. We see the formation of boundary layers in some of these submodels, across which the concentration of polar lipid and the non-polar lipid velocity and film thickness vary. We solve our model numerically for physically realistic parameter values, and we find that the evolution of the aqueous layer and the polar lipid layer are similar to that described by previous authors. However, there are interesting dynamics for the non-polar lipid layer. The effects of altering the key parameters are highlighted and discussed. In particular, we see that the Marangoni number plays a key role in determining how far over the eye the non-polar lipid spreads.

  1. Mechanism of Nonpolar Model Substances to Inhibit Primary Gushing Induced by Hydrophobin HFBI.

    Science.gov (United States)

    Shokribousjein, Zahra; Riveros Galan, David; Losada-Pérez, Patricia; Wagner, Patrick; Lammertyn, Jeroen; Arghir, Iulia; Golreihan, Asefeh; Verachtert, Hubert; Aydın, Ahmet Alper; De Maeyer, Marc; Titze, Jean; Ilberg, Vladimír; Derdelinckx, Guy

    2015-05-13

    In this work, the interactions of a well-studied hydrophobin with different types of nonpolar model substances and their impact on primary gushing is evaluated. The nature, length, and degree of saturation of nonpolar molecules are key parameters defining the gushing ability or inhibition. When mixed with hydrophobins, the nonpolar molecule-hydrophobin assembly acts as a less gushing or no gushing system. This effect can be explained in the framework of a competition effect between non-polar systems and CO2 to interact with the hydrophobic patch of the hydrophobin. Interactions of these molecules with hydrophobins are promoted as a result of the similar size of the nonpolar molecules with the hydrophobic patch of the protein, at the expense of the formation of nanobubbles with CO2. In order to prove the presence of interactions and to unravel the mechanisms behind them, a complete set of experimental techniques was used. Surface sensitive techniques clearly show the presence of the interactions, whose nature is not covalent nor hydrogen bonding according to infrared spectroscopy results. Interactions were also reflected by particle size analysis in which mixtures of particles displayed larger size than their pure component counterparts. Upon mixing with nonpolar molecules, the gushing ability of the protein is significantly disrupted.

  2. Deviations from sorption linearity on soils of polar and nonpolar organic compounds at low relative concentrations

    Science.gov (United States)

    Chiou, C.T.; Kile, D.E.

    1998-01-01

    A series of single-solute and binary-solute sorption data have been obtained on representative samples of polar compounds (substituted ureas and phenolic compounds) and of nonpolar compounds (e.g., EDB and TCE) on a peat soil and a mineral (Woodburn) soil; the data extend to low relative solute concentrations (C(e)/S(w)). At relatively low C(e)/S(w), both the nonpolar and the polar solutes exhibit nonlinear sorption. The sorption nonlinearity approaches apparent saturation at about C(e)/S(w) = 0.010-0.015 for the nonpolar solutes and at about C(e)/S(w) = 0.10-0.13 for the polar solutes; above these C(e)/S(w) regions, the isotherms are practically linear. The nonlinear sorption capacities are greater for polar solutes than for nonpolar solutes and the peat soil shows a greater effect than the Woodburn soil. The small nonlinear sorption capacity for a nonpolar solute is suppressed indiscriminately by either a nonpolar or a polar cosolute at relatively low C(e)/S(w) of the cosolute. By contrast, the abilities of different cosolutes to suppress the nonlinear capacity of a nominal polar solute differ drastically. For polar solutes, a nonpolar cosolute exhibits a limited suppression even at high cosolute C(e)/S(w); effective suppression occurs when the cosolute is relatively polar and at various C(e)/S(w). These differences suggest that more than a single mechanism is required to account for the nonlinear sorption of both nonpolar and polar compounds at low C(e)/S(w). Mechanistic processes consistent with these observations and with soil surface areas are discussed along with other suggested models. Some important consequences of the nonlinear competitive sorption to the behavior of contaminants in natural systems are discussed.A number of conceptual models was postulated to account for the nonlinear solute sorption on soils of significant soil organic matter. A series of single-solute and binary-route sorption data was obtained representing samples of polar compounds of

  3. Methods for recovering a solvent from a fluid volume and methods of removing at least one compound from a nonpolar solvent

    Energy Technology Data Exchange (ETDEWEB)

    Ginosar, Daniel M.; Wendt, Daniel S.; Petkovic, Lucia M.

    2014-06-10

    A method of removing a nonpolar solvent from a fluid volume that includes at least one nonpolar compound, such as a fat, an oil or a triglyceride, is provided. The method comprises contacting a fluid volume with an expanding gas to expand the nonpolar solvent and form a gas-expanded solvent. The gas-expanded solvent may have a substantially reduced density in comparison to the at least one nonpolar compound and/or a substantially reduced capacity to solubilize the nonpolar compound, causing the nonpolar compounds to separate from the gas-expanded nonpolar solvent into a separate liquid phase. The liquid phase including the at least one nonpolar compound may be separated from the gas-expanded solvent using conventional techniques. After separation of the liquid phase, at least one of the temperature and pressure may be reduced to separate the nonpolar solvent from the expanding gas such that the nonpolar solvent may be recovered and reused.

  4. Treatment of tunnel wash waters - experiments with organic sorbent materials. Part I: Removal of polycyclic aromatic hydrocarbons and nonpolar oil

    Institute of Scientific and Technical Information of China (English)

    PARUCH AdamM; ROSETH Roger

    2008-01-01

    Tunnel wash waters characterize all waters that run off after washing procedures of tunnels are performed. These waters represent a wide spectrum of organic and inorganic pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and toxic metals. Removal of such contaminants from water runoff was investigated using laboratory tests after washing procedure was performed on two road tunnels in eastern Norway (Hanekleiv and Bragernes). Due to diverse character of both, treatment media and treated wash waters, the whole investigation was divided into two separate laboratory experiments. The treatment efficiencies were established based on the levels of concentrations and reductions of the measured contaminants in the effluents released from the tested media. In the first part of the article, the contents of nonpolar oil (NPO), 16 individual PAHs, and total PAHs (∑PAH16) are described. This part revealed that the combination of two organic sorbent materials provided the highest treatment efficiency for wash waters released from the road tunnel and from electrostatic filters. The greatest reduction levels reached 97.6% for NPO, 97.2% for benzo[a]pyrene, and 96.5% for the total PAHs. In the second part of the article, the concentrations and the removal rates of toxic metals are reported

  5. Simulation of Nonpolar p-GaN/i-N/n-GaN Solar Cells

    Directory of Open Access Journals (Sweden)

    Ming-Jer Jeng

    2012-01-01

    Full Text Available It is well known that nitride-based devices suffer the polarization effects. A promising way to overcome the polarization effects is growth in a direction perpendicular to the c-axis (nonpolar direction. Nonpolar devices do not suffer polarization charge, and then they have a chance to achieve the high solar efficiency. The understanding of the solar performance of non-polar InGaN-based solar cells will be interesting. For a pin non-polar solar cell with GaN p- and n-cladding layers, the conduction band offset (or barrier height, between an intrinsic layer and n-GaN layer is an important issue correlating to the efficiency and fill factor. The efficiency and fill factor will be seriously degraded due to sufficiently high barrier height. To reduce a high barrier height, some graded layers with an energy bandgap between the energy bandgap of n-GaN and InxGa1−xN intrinsic layer can be inserted to the interface of n-GaN and InxGa1-xN layers. From simulation, it indicates that the insertion of graded layer is an effective method to lower energy barrier when there exists a high energy band offset in non-polar nitride devices.

  6. Large organized surface domains self-assembled from nonpolar amphiphiles.

    Science.gov (United States)

    Krafft, Marie Pierre

    2012-04-17

    unambiguously demonstrated the presence of surface micelles in monolayers of diblocks prior to LB transfer for atomic force microscopy imaging. We characterized an almost perfect two-dimensional crystal, with 12 assignable diffraction peaks, which established that self-assembly and regular nanopatterning were not caused by transfer or induced by the solid support. These experiments also provide the first direct identification of surface micelles on water, and the first identification of such large-size domains using GISAXS. Revisiting Langmuir film compression behavior after we realized that it actually was a compression of nanometric objects led to further unanticipated observations. These films could be compressed far beyond the documented film "collapse", eventually leading to the buildup of two superimposed, less-organized bilayers of diblocks on top of the initially formed monolayer of hemimicelles. Remarkably, the latter withstood the final, irreversible collapse of the composite films. "Gemini" tetrablocks, di(FnHm), with two Fn-chains and two Hm-chains, provided two superposed layers of discrete micelles, apparently the first example of thin films made of stacked discrete self-assembled nanoobjects. Decoration of solid surfaces with domains of predetermined size of these small "nonpolar" molecules is straightforward. Initial examples of applications include deposition of metal dots and catalytic oxidation of CO, and nanopatterning of SiO(2) films.

  7. Passive Sampling in Regulatory Chemical Monitoring of Nonpolar Organic Compounds in the Aquatic Environment

    DEFF Research Database (Denmark)

    Booij, Kees; Robinson, Craig D; Burgess, Robert M;

    2016-01-01

    We reviewed compliance monitoring requirements in the European Union, the United States, and the Oslo-Paris Convention for the protection of the marine environment of the North-East Atlantic, and evaluated if these are met by passive sampling methods for nonpolar compounds. The strengths and shor...... is the best available technology for chemical monitoring of nonpolar organic compounds. Key issues to be addressed by scientists and environmental managers are outlined.......We reviewed compliance monitoring requirements in the European Union, the United States, and the Oslo-Paris Convention for the protection of the marine environment of the North-East Atlantic, and evaluated if these are met by passive sampling methods for nonpolar compounds. The strengths...... and shortcomings of passive sampling are assessed for water, sediments, and biota. Passive water sampling is a suitable technique for measuring concentrations of freely dissolved compounds. This method yields results that are incompatible with the EU's quality standard definition in terms of total concentrations...

  8. Investigation of the Phase Equilibria and Interfacial Properties for Non-polar Fluids

    Institute of Scientific and Technical Information of China (English)

    付东; 赵毅

    2005-01-01

    A self-consistent density-functional theory (DFT) was applied to investigate the phase behavior and interfacial properties of non-polar fluids. For the bulk phases, the theory was reduced to the statistical associating fluid theory(SAFF) that provides accurate descriptions of vapor-liquid phase diagrams below the critical region. The phase diagrams in the critical region were corrected by the renormalization group theory (RGT). The density profile in the surface was obtained by minimizing the grand potential. With the same set of molecular parameters, both the phase equilibria and the interfacial properties of non-polar fluids were investigated satisfactorily.

  9. 含氟介质中乌洛托品硝解制RDX研究%Preparation of RDX by Nitrolysis of Hexamethylenetetramine in Fluorous Media

    Institute of Scientific and Technical Information of China (English)

    易文斌; 蔡春

    2008-01-01

    以全氟辛基磺酸(C8F17SO3H,PfOS)和全氟萘烷(C10F18,顺式与反式的混合物)分别为催化剂和氟溶剂,用硝酸硝解乌洛托品制备黑索今(RDX).过程比传统方法产生更少的废酸和硝酸盐.考察了硝酸、催化剂和硝酸铵用量,反应温度,反应时间,以及氟-水两相相比对反应的影响.研究表明,当硝酸和硝酸铵摩尔用量分别为底物的10倍和0.5倍时,用摩尔分数为10%的PfOS作催化剂,乌洛托品在20 ℃下反应6 h后得到RDX,得率为129.4%(以1 mol乌洛托品生成1 mol RDX计算).含有催化剂的氟相通过简单的相分离,就可回收利用,氟相重复使用5次,其催化活性减少不大.

  10. Passive sampling in regulatory chemical monitoring of nonpolar organic compounds in the aquatic environment

    NARCIS (Netherlands)

    Booij, K.; Robinson, C.D.; Burgess, R.M.; Mayer, P.; Roberts, C.A.; Ahrens, L.; Allan, I.J.; Brant, J.; Jones, L.; Kraus, U.R.; Larsen, M.M.; Lepom, P.; Petersen, J.; Pröfrock, D.; Roose, P.; Schäfer, S.; Smedes, F.; Tixier, C.; Vorkamp, K.; Whitehouse, P.

    2016-01-01

    We reviewed compliance monitoring requirements in the EuropeanUnion, the United States, and the Oslo-Paris Convention for the protection of themarine environment of the North-East Atlantic, and evaluated if these are met bypassive sampling methods for nonpolar compounds. The strengths andshortcoming

  11. Determinatin of the Dipole Moment of Polar Compounds in Nonpolar Solvents.

    Science.gov (United States)

    Janini, George M.; Katrib, Ali H.

    1983-01-01

    Proposes a simple experiment based on the procedure of Guggenheim and Smith for the determinatin of the dipole moments of two isomeric compounds in nonpolar solvents. Provides background information, laboratory procedures, sample data, results of least squares analysis and discussion of results. (JM)

  12. Surface chemistry and electronic structure of nonpolar and polar GaN films

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Monu; Krishna, T.C. Shibin; Aggarwal, Neha; Gupta, Govind, E-mail: govind@nplindia.org

    2015-08-01

    Highlights: • Surface chemistry and electronic structure of polar and nonpolar GaN is reported. • Influence of polarization on electron affinity of p & np GaN films is investigated. • Correlation between surface morphology and polarity has been deduced. - Abstract: Photoemission and microscopic analysis of nonpolar (a-GaN/r-Sapphire) and polar (c-GaN/c-Sapphire) epitaxial gallium nitride (GaN) films grown via RF-Molecular Beam Epitaxy is reported. The effect of polarization on surface properties like surface states, electronic structure, chemical bonding and morphology has been investigated and correlated. It was observed that polarization lead to shifts in core level (CL) as well as valence band (VB) spectra. Angle dependent X-ray Photoelectron Spectroscopic analysis revealed higher surface oxide in polar GaN film compared to nonpolar GaN film. On varying the take off angle (TOA) from 0° to 60°, the Ga−O/Ga−N ratio varied from 0.11–0.23 for nonpolar and 0.17–0.36 for polar GaN film. The nonpolar film exhibited N-face polarity while Ga-face polarity was perceived in polar GaN film due to the inherent polarization effect. Polarization charge compensated surface states were observed on the polar GaN film and resulted in downward band bending. Ultraviolet photoelectron spectroscopic measurements revealed electron affinity and ionization energy of 3.4 ± 0.1 eV and 6.8 ± 0.1 eV for nonpolar GaN film and 3.8 ± 0.1 eV and 7.2 ± 0.1 eV for polar GaN film respectively. Field Emission Scanning Electron Microscopy measurements divulged smooth morphology with pits on polar GaN film. The nonpolar film on the other hand showed pyramidal structures having facets all over the surface.

  13. Insulin adsorption on crystalline SiO2: Comparison between polar and nonpolar surfaces using accelerated molecular-dynamics simulations

    Science.gov (United States)

    Nejad, Marjan A.; Mücksch, Christian; Urbassek, Herbert M.

    2017-02-01

    Adsorption of insulin on polar and nonpolar surfaces of crystalline SiO2 (cristobalite and α -quartz) is studied using molecular dynamics simulation. Acceleration techniques are used in order to sample adsorption phase space efficiently and to identify realistic adsorption conformations. We find major differences between the polar and nonpolar surfaces. Electrostatic interactions govern the adsorption on polar surfaces and can be described by the alignment of the protein dipole with the surface dipole; hence spreading of the protein on the surface is irrelevant. On nonpolar surfaces, on the other hand, van-der-Waals interaction dominates, inducing surface spreading of the protein.

  14. Quantum theory of interfacial tension quantitatively predicts spontaneous charging of nonpolar aqueous interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Fernández, Ariel, E-mail: ariel@afinnovation.com [Argentine Institute of Mathematics (I. A. M.), National Research Council (CONICET), Buenos Aires 1083 (Argentina); Collegium Basilea – Institute for Advanced Study, Basel CH4053 (Switzerland)

    2015-10-16

    The spontaneous negative charging of aqueous nonpolar interfaces has eluded quantitative first-principle prediction, possibly because it steadfastly challenges the classical Debye dielectric picture. In this work we show that quantitative prediction requires a substantive revision of Debye's linear dielectric ansatz to incorporate an anomalous polarization component yielding electrostatic energy stored as interfacial tension and detailed enough to account for the differences in electronic structure between water and its ionized states. The minimization of this interfacial tension is due to a quantum effect resulting in the reduction in hydrogen-bond frustration that takes place upon hydroxide ion adsorption. The quantitative predictions are validated vis-à-vis measurements of the free energy change associated with hydroxide adsorption obtained using sum-frequency vibrational spectroscopy. - Highlights: • Spontaneous charging of aqueous nonpolar interfaces challenges Debye dielectrics. • A quantum non-Debye theory of interfacial tension is developed. • The minimization of the interfacial tension promotes hydroxide ion adsorption.

  15. A Simple Method for Estimation of Dielectric Constants and Polarizabilities of Nonpolar and Slightly Polar Hydrocarbons

    Science.gov (United States)

    Panuganti, Sai R.; Wang, Fei; Chapman, Walter G.; Vargas, Francisco M.

    2016-07-01

    Many of the liquids that are used as electrical insulators are nonpolar or slightly polar petroleum-derived hydrocarbons, such as the ones used for cable and/or transformer oils. In this work, semi-empirical expressions with no adjustable parameters for the dielectric constant and the polarizability of nonpolar and slightly polar hydrocarbons and their mixtures are proposed and validated. The expressions that were derived using the Vargas-Chapman One-Third rule require the mass density and the molecular weight of the substance of interest. The equations were successfully tested for various hydrocarbons and polymers with dipole moments eliminate the need of extensive experimental data and require less input parameters compared to existing correlations.

  16. Influence of oxygen in architecting large scale nonpolar GaN nanowires

    CERN Document Server

    Patsha, Avinash; Pandian, Ramanathaswamy; Dhara, S

    2015-01-01

    Manipulation of surface architecture of semiconducting nanowires with a control in surface polarity is one of the important objectives for nanowire based electronic and optoelectronic devices for commercialization. We report the growth of exceptionally high structural and optical quality nonpolar GaN nanowires with controlled and uniform surface morphology and size distribution, for large scale production. The role of O contamination (~1-10^5 ppm) in the surface architecture of these nanowires is investigated with the possible mechanism involved. Nonpolar GaN nanowires grown in O rich condition show the inhomogeneous surface morphologies and sizes (50 - 150 nm) while nanowires are having precise sizes of 40(5) nm and uniform surface morphology, for the samples grown in O reduced condition. Relative O contents are estimated using electron energy loss spectroscopy studies. Size-selective growth of uniform nanowires is also demonstrated, in the O reduced condition, using different catalyst sizes. Photoluminescen...

  17. Vertical nonpolar growth templates for light emitting diodes formed with GaN nanosheets

    Science.gov (United States)

    Yeh, Ting-Wei; Lin, Yen-Ting; Ahn, Byungmin; Stewart, Lawrence S.; Daniel Dapkus, P.; Nutt, Steven R.

    2012-01-01

    We demonstrate that nonpolar m-plane surfaces can be generated on uniform GaN nanosheet arrays grown vertically from the (0001)-GaN bulk material. InGaN/GaN multiple quantum wells (MQWs) grown on the facets of these nanosheets are demonstrated by cross-sectional transmission electron microscopy. Owing to the high aspect ratio of the GaN nanosheet structure, the MQWs predominantly grow on nonpolar GaN planes. The results suggest that GaN nanosheets provide a conduction path for device fabrication and also a growth template to reduce the piezoelectric field inside the active region of InGaN-based light emitting diodes.

  18. Electrokinetics of Polar Liquids in Contact with Non-Polar Surfaces

    CERN Document Server

    Lin, Chih-Hsiu; Chaudhury, Manoj K

    2014-01-01

    Zeta potentials of several polar protic (water, ethylene glycol, formamide) as well as polar aprotic (dimethyl sulfoxide) liquids were measured in contact with three non-polar surfaces using closed-cell electro-osmosis. The test surfaces were chemisorbed monolayers of alkyl siloxanes, fluoroalkyl siloxanes and polydimethylsiloxanes (PDMS) grafted on glass slides. All these liquids exhibited substantial electrokinetics in contact with the non-polar surfaces with these observations: the electrokinetic effect on the fluorocarbon-coated surface is the strongest; and on a PDMS grafted surface, the effect is the weakest. Even though these hygroscopic liquids contain small amounts of water, the current models of charging based on the adsorption of hydroxide ions at the interface or the dissociation of preexisting functionalities (e.g., silanol groups) appear to be insufficient to account for the various facets of the experimental observations. The results illustrate how ubiquitous the phenomenon of electro-kinetics ...

  19. Stable and efficient colour enrichment powders of nonpolar nanocrystals in LiCl

    Science.gov (United States)

    Erdem, Talha; Soran-Erdem, Zeliha; Sharma, Vijay Kumar; Kelestemur, Yusuf; Adam, Marcus; Gaponik, Nikolai; Demir, Hilmi Volkan

    2015-10-01

    In this work, we propose and develop the inorganic salt encapsulation of semiconductor nanocrystal (NC) dispersion in a nonpolar phase to make a highly stable and highly efficient colour converting powder for colour enrichment in light-emitting diode backlighting. Here the wrapping of the as-synthesized green-emitting CdSe/CdZnSeS/ZnS nanocrystals into a salt matrix without ligand exchange is uniquely enabled by using a LiCl ionic host dissolved in tetrahydrofuran (THF), which simultaneously disperses these nonpolar nanocrystals. We studied the emission stability of the solid films prepared using NCs with and without LiCl encapsulation on blue LEDs driven at high current levels. The encapsulated NC powder in epoxy preserved 95.5% of the initial emission intensity and stabilized at this level while the emission intensity of NCs without salt encapsulation continuously decreased to 34.7% of its initial value after 96 h of operation. In addition, we investigated the effect of ionic salt encapsulation on the quantum efficiency of nonpolar NCs and found the quantum efficiency of the NCs-in-LiCl to be 75.1% while that of the NCs in dispersion was 73.0% and that in a film without LiCl encapsulation was 67.9%. We believe that such ionic salt encapsulated powders of nonpolar NCs presented here will find ubiquitous use for colour enrichment in display backlighting.In this work, we propose and develop the inorganic salt encapsulation of semiconductor nanocrystal (NC) dispersion in a nonpolar phase to make a highly stable and highly efficient colour converting powder for colour enrichment in light-emitting diode backlighting. Here the wrapping of the as-synthesized green-emitting CdSe/CdZnSeS/ZnS nanocrystals into a salt matrix without ligand exchange is uniquely enabled by using a LiCl ionic host dissolved in tetrahydrofuran (THF), which simultaneously disperses these nonpolar nanocrystals. We studied the emission stability of the solid films prepared using NCs with and

  20. Broadband non-polarizing terahertz beam splitters with variable split ratio

    KAUST Repository

    Wei, Minggui

    2017-08-15

    Seeking effective terahertz functional devices has always aroused extensive attention. Of particular interest is the terahertz beam splitter. Here, we have proposed, designed, manufactured, and tested a broadband non-polarizing terahertz beam splitter with a variable split ratio based on an all-dielectric metasurface. The metasurface was created by patterning a dielectric surface of the N-step phase gradient and etching to a few hundred micrometers. The conversion efficiency as high as 81% under the normal incidence at 0.7 THz was achieved. Meanwhile, such a splitter works well over a broad frequency range. The split ratio of the proposed design can be continuously tuned by simply shifting the metasurface, and the angle of emergences can also be easily adjusted by choosing the step of phase gradients. The proposed design is non-polarizing, and its performance is kept under different polarizations.

  1. Non-polar Solvent Microwave-Assisted Extraction of Volatile Constituents from Dried Zingiber Officinale Rosc.

    Institute of Scientific and Technical Information of China (English)

    YU Yong; WANG Zi-Ming; WANG Yu-Tang; LI Tie-Chun; CHENG Jian-Hua; LIU Zhong-Ying; ZHANG Han-Qi

    2007-01-01

    A new method, non-polar solvent microwave-assisted extraction (NPSMAE), was applied to the extraction of essential oil from Zingiber officinale Rosc. in closed-vessel system. By adding microwave absorption mediumcarbonyl iron powders (CIP) into extraction system, the essential oil was extracted by the non-polar solvent (ether)which can be heated by CIP. The constituents of essential oil obtained by NPSMAE were comparable with those obtained by hydrodistillation (HD) by GC-MS analysis, which indicates that NPSMAE is a feasible way to extract essential oil from dried plant materials. The NPSMAE took much less extraction time (5 min) than HD (180 min),and its extraction efficiency was much higher than that of conventional polar solvent microwave-assisted extraction (PSMAE) and mixed solvent microwave-assisted extraction (MSMAE). It can be a good alternative for the extraction of volatile constituents from dried plant samples.

  2. Isolating the non-polar contributions to the intermolecular potential for water-alkane interactions.

    Science.gov (United States)

    Ballal, Deepti; Venkataraman, Pradeep; Fouad, Wael A; Cox, Kenneth R; Chapman, Walter G

    2014-08-14

    Intermolecular potential models for water and alkanes describe pure component properties fairly well, but fail to reproduce properties of water-alkane mixtures. Understanding interactions between water and non-polar molecules like alkanes is important not only for the hydrocarbon industry but has implications to biological processes as well. Although non-polar solutes in water have been widely studied, much less work has focused on water in non-polar solvents. In this study we calculate the solubility of water in different alkanes (methane to dodecane) at ambient conditions where the water content in alkanes is very low so that the non-polar water-alkane interactions determine solubility. Only the alkane-rich phase is simulated since the fugacity of water in the water rich phase is calculated from an accurate equation of state. Using the SPC/E model for water and TraPPE model for alkanes along with Lorentz-Berthelot mixing rules for the cross parameters produces a water solubility that is an order of magnitude lower than the experimental value. It is found that an effective water Lennard-Jones energy ε(W)/k = 220 K is required to match the experimental water solubility in TraPPE alkanes. This number is much higher than used in most simulation water models (SPC/E-ε(W)/k = 78.2 K). It is surprising that the interaction energy obtained here is also higher than the water-alkane interaction energy predicted by studies on solubility of alkanes in water. The reason for this high water-alkane interaction energy is not completely understood. Some factors that might contribute to the large interaction energy, such as polarizability of alkanes, octupole moment of methane, and clustering of water at low concentrations in alkanes, are examined. It is found that, though important, these factors do not completely explain the anomalously strong attraction between alkanes and water observed experimentally.

  3. A comparative DFT study of the structural and electronic properties of nonpolar GaN surfaces

    Energy Technology Data Exchange (ETDEWEB)

    González-Hernández, Rafael, E-mail: rhernandezj@uninorte.edu.co [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); González-García, Alvaro [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); Barragán-Yani, Daniel [Fachgebiet Material modellierung, Institut für Materialwissenschaft, Technische Universität Darmstadt, Jovanka-Bontschits-Straße 2, 64287 Darmstadt (Germany); López-Pérez, William [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia)

    2014-09-30

    Highlights: • A comparative analysis of the geometry and the electronic characteristics of nonpolar GaN surfaces was carried out. • Surface energies are too low for LDA, but lower still for GGA and MGGA functionals, except for PBEsol. • PBEsol exhibits good lattice parameters and surface energies. • Surface intra-gap states reduce the band gap of the nonpolar GaN surfaces. • Slight changes in the dispersion of surface states were observed for the LDA, GGA, and MGGA functionals. - Abstract: A comparative analysis of the geometry and the electronic characteristics of nonpolar GaN surfaces was carried out using density-functional theory (DFT) with different approximations for the exchange-correlation energy (LDA, PBE, PBEsol, RPBE, TPSS, revTPSS, and HSE). The obtained data show that the GaN(101{sup ¯}0) (m-plane) is more energetically stable than the GaN(112{sup ¯}0) (a-plane) surface. However, these surfaces have similar surface relaxation geometry, with a Ga-N surface bond-length contraction of around 6–7% and a Ga-N surface rotational angle in the range of 6–9°. Our results show that the use of different exchange-correlation functionals does not significantly change the surface energy and surface geometry. In addition, we found the presence of surface intra-gap states that reduce the band gap of the nonpolar GaN surface with respect to the bulk value, in agreement with recent photoelectron and surface optical spectroscopy experiments.

  4. Contact angles and wettability of ionic liquids on polar and non-polar surfaces.

    Science.gov (United States)

    Pereira, Matheus M; Kurnia, Kiki A; Sousa, Filipa L; Silva, Nuno J O; Lopes-da-Silva, José A; Coutinho, João A P; Freire, Mara G

    2015-12-21

    Many applications involving ionic liquids (ILs) require the knowledge of their interfacial behaviour, such as wettability and adhesion. In this context, herein, two approaches were combined aiming at understanding the impact of the IL chemical structures on their wettability on both polar and non-polar surfaces, namely: (i) the experimental determination of the contact angles of a broad range of ILs (covering a wide number of anions of variable polarity, cations, and cation alkyl side chain lengths) on polar and non-polar solid substrates (glass, Al-plate, and poly-(tetrafluoroethylene) (PTFE)); and (ii) the correlation of the experimental contact angles with the cation-anion pair interaction energies generated by the Conductor-like Screening Model for Real Solvents (COSMO-RS). The combined results reveal that the hydrogen-bond basicity of ILs, and thus the IL anion, plays a major role through their wettability on both polar and non-polar surfaces. The increase of the IL hydrogen-bond accepting ability leads to an improved wettability of more polar surfaces (lower contact angles) while the opposite trend is observed on non-polar surfaces. The cation nature and alkyl side chain lengths have however a smaller impact on the wetting ability of ILs. Linear correlations were found between the experimental contact angles and the cation-anion hydrogen-bonding and cation ring energies, estimated using COSMO-RS, suggesting that these features primarily control the wetting ability of ILs. Furthermore, two-descriptor correlations are proposed here to predict the contact angles of a wide variety of ILs on glass, Al-plate, and PTFE surfaces. A new extended list is provided for the contact angles of ILs on three surfaces, which can be used as a priori information to choose appropriate ILs before a given application.

  5. Contact angles and wettability of ionic liquids on polar and non-polar surfaces†

    Science.gov (United States)

    Sousa, Filipa L.; Silva, Nuno J. O.; Lopes-da-Silva, José A.; Coutinho, João A. P.; Freire, Mara G.

    2016-01-01

    Many applications involving ionic liquids (ILs) require the knowledge of their interfacial behaviour, such as wettability and adhesion. In this context, herein, two approaches were combined aiming at understanding the impact of the IL chemical structures on their wettability on both polar and non-polar surfaces, namely: (i) the experimental determination of the contact angles of a broad range of ILs (covering a wide number of anions of variable polarity, cations, and cation alkyl side chain lengths) on polar and non-polar solid substrates (glass, Al-plate, and poly-(tetrafluoroethylene) (PTFE)); and (ii) the correlation of the experimental contact angles with the cation–anion pair interaction energies generated by the Conductor-like Screening Model for Real Solvents (COSMO-RS). The combined results reveal that the hydrogen-bond basicity of ILs, and thus the IL anion, plays a major role through their wettability on both polar and non-polar surfaces. The increase of the IL hydrogen-bond accepting ability leads to an improved wettability of more polar surfaces (lower contact angles) while the opposite trend is observed on non-polar surfaces. The cation nature and alkyl side chain lengths have however a smaller impact on the wetting ability of ILs. Linear correlations were found between the experimental contact angles and the cation–anion hydrogen-bonding and cation ring energies, estimated using COSMO-RS, suggesting that these features primarily control the wetting ability of ILs. Furthermore, two-descriptor correlations are proposed here to predict the contact angles of a wide variety of ILs on glass, Al-plate, and PTFE surfaces. A new extended list is provided for the contact angles of ILs on three surfaces, which can be used as a priori information to choose appropriate ILs before a given application. PMID:26554705

  6. Modeling diffusion coefficients in binary mixtures of polar and non-polar compounds

    DEFF Research Database (Denmark)

    Medvedev, Oleg; Shapiro, Alexander

    2005-01-01

    The theory of transport coefficients in liquids, developed previously, is tested on a description of the diffusion coefficients in binary polar/non-polar mixtures, by applying advanced thermodynamic models. Comparison to a large set of experimental data shows good performance of the model. Only...... components and to only one parameter for mixtures consisting of non-polar components. A possibility of complete prediction of the parameters is discussed....

  7. Hydrophobic monolayered nanoflakes of tungsten oxide: coupled exfoliation and fracture in a nonpolar organic medium.

    Science.gov (United States)

    Honda, Masashi; Oaki, Yuya; Imai, Hiroaki

    2015-06-21

    Coupled exfoliation and fracture induced formation of hydrophobic monolayered nanoflakes in a nonpolar organic medium. The hydrophobic monolayered nanoflakes 5-20 nm in lateral size consisted of a tungstate layer with surface modification by stearylammonium ions (C18H37NH3)0.397 H0.603Cs3W11O35·xH2O (x < 0.625).

  8. Electric Charge Accumulation in Polar and Non-Polar Polymers under Electron Beam Irradiation

    Science.gov (United States)

    Nagasawa, Kenichiro; Honjoh, Masato; Takada, Tatsuo; Miyake, Hiroaki; Tanaka, Yasuhiro

    The electric charge accumulation under an electron beam irradiation (40 keV and 60 keV) was measured by using the pressure wave propagation (PWP) method in the dielectric insulation materials, such as polar polymeric films (polycarbonate (PC), polyethylene-naphthalate (PEN), polyimide (PI), and polyethylene-terephthalate (PET)) and non-polar polymeric films (polystyrene (PS), polypropylene (PP), polyethylene (PE) and polytetrafluoroethylene (PTFE)). The PE and PTFE (non-polar polymers) showed the properties of large amount of electric charge accumulation over 50 C/m3 and long saturation time over 80 minutes. The PP and PS (non-polar polymer) showed the properties of middle amount of charge accumulation about 20 C/m3 and middle saturation time about 1 to 20 minutes. The PC, PEN, PI and PET (polar polymers) showed the properties of small amount of charge accumulation about 5 to 20 C/m3 and within short saturation time about 1.0 minutes. This paper summarizes the relationship between the properties of charge accumulation and chemical structural formula, and compares between the electro static potential distribution with negative charged polymer and its chemical structural formula.

  9. Enhanced UV detection by non-polar epitaxial GaN films

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Shruti; Chandan, Greeshma; Mohan, Lokesh; Krupanidhi, S. B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore (India); Roul, Basanta [Materials Research Centre, Indian Institute of Science, Bangalore (India); Central Research Laboratory, Bharat Electronics, Bangalore (India); Shetty, Arjun [Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore (India)

    2015-12-15

    Nonpolar a-GaN (11-20) epilayers were grown on r-plane (1-102) sapphire substrates using plasma assisted molecular beam epitaxy. High resolution x-ray diffractometer confirmed the orientation of the grown film. Effect of the Ga/N ratio on the morphology and strain of a-GaN epilayers was compared and the best condition was obtained for the nitrogen flow of 1 sccm. Atomic force microscopy was used to analyze the surface morphology while the strain in the film was quantitatively measured using Raman spectroscopy and qualitatively analyzed by reciprocal space mapping technique. UV photo response of a-GaN film was measured after fabricating a metal-semiconductor-metal structure over the film with gold metal. The external quantum efficiency of the photodetectors fabricated in the (0002) polar and (11-20) nonpolar growth directions were compared in terms of responsivity and nonpolar GaN showed the best sensitivity at the cost of comparatively slow response time.

  10. Chemical etching behaviors of semipolar (11̄22) and nonpolar (11̄20) gallium nitride films.

    Science.gov (United States)

    Jung, Younghun; Baik, Kwang Hyeon; Mastro, Michael A; Hite, Jennifer K; Eddy, Charles R; Kim, Jihyun

    2014-08-14

    Wet chemical etching using hot KOH and H3PO4 solutions was performed on semipolar (11̄22) and nonpolar (11̄20) GaN films grown on sapphire substrates. An alternating KOH/H3PO4/KOH etch process was developed to control the orientation of the facets on the thin-film surface. The initial etch step in KOH produced c- and m-plane facets on the surface of both semipolar (11̄22) and nonpolar (11̄20) GaN thin-films. A second etch step in H3PO4 solution additionally exposed a (̄1̄12̄2) plane, which is chemically stable in H3PO4 solution. By repeating the chemical etch with KOH solution, the m-plane facets as seen in the original KOH etch step were recovered. The etching methods developed in our work can be used to control the surface morphologies of nonpolar and semipolar GaN-based optoelectronic devices such as light-emitting diodes and solar cells.

  11. Enhanced sensing of nonpolar volatile organic compounds by silicon nanowire field effect transistors.

    Science.gov (United States)

    Paska, Yair; Stelzner, Thomas; Christiansen, Silke; Haick, Hossam

    2011-07-26

    Silicon nanowire field effect transistors (Si NW FETs) are emerging as powerful sensors for direct detection of biological and chemical species. However, the low sensitivity of the Si NW FET sensors toward nonpolar volatile organic compounds (VOCs) is problematic for many applications. In this study, we show that modifying Si NW FETs with a silane monolayer having a low fraction of Si-O-Si bonds between the adjacent molecules greatly enhances the sensitivity toward nonpolar VOCs. This can be explained in terms of an indirect sensor-VOC interaction, whereby the nonpolar VOC molecules induce conformational changes in the organic monolayer, affecting (i) the dielectric constant and/or effective dipole moment of the organic monolayer and/or (ii) the density of charged surface states at the SiO(2)/monolayer interface. In contrast, polar VOCs are sensed directly via VOC-induced changes in the Si NW charge carriers, most probably due to electrostatic interaction between the Si NW and polar VOCs. A semiempirical model for the VOC-induced conductivity changes in the Si NW FETs is presented and discussed.

  12. Measurement and Modeling of Carbon Dioxide Solubility in Polar and Nonpolar Solvent

    Directory of Open Access Journals (Sweden)

    Hojatollah Ahmadi

    2012-08-01

    Full Text Available The solubility of gases is an important issue in the industries. Carbon Dioxide Through gas transmission line exists as sour gas therefore it is eliminated by solvent in industry. Carbone Dioxide is nonpolar molecule that has lower solubility in liquid solvent. In this study the solubility of carbon dioxide in some polar and nonpolar solvents (include Acetone, Acetic Acid, Benzene, Carbon Tetra Chloride, Chlorobenzene, Chloroform, Cyclo-hexane, Di-Methyl Formamid, Ethanol, Ethyl acetate, Methanol, NButanol, N-Heptane, N-Hexane at atmospheric pressure and temperatures range from 5-35ºC was determined. A laboratory unit was made for this experience and the solubility of CO2 was reported. The solubility of carbon dioxide in these solvent was low due to unreactivity and nonpolarity nature of these material. The solubility of CO2 in Ethyl Acetate and Methanol was highest and lowest respectively. This investigation showed that the solvent with carbonyl group have higher activity than other.

  13. High-pressure single-crystal X-ray diffraction study on Super Fluorous Phase B up to 7.4 GPa

    Science.gov (United States)

    Kuribayashi, T.; Kojitani, H.; Nagase, T.; Akaogi, M.; Mao, H.; Hemley, R.; Kudoh, Y.

    2008-12-01

    Super hydrous phase B (SUP-B), Mg10Si3O14(OH)4, is known as one of dense hydrous magnesium silicate minerals (DHMS). Also, super fluorous phase B (sup-B-F), Mg10Si3O14F4, was firstly synthesized by Hazen et al. (1997). In the crystal structure of SUP-B-F, F replaces OH in sup-B structure. Therefore, differences of behavior between SUP-B-F and SUP-B under high-pressure conditions directory reflect the effect of hydrogen bonding. In this study, to clarify the behavior of SUP-B-F under high-pressure condition, SUP-B-F was synthesized at 21 GPa and 1400°C conditions using the Kawai type multi anvil apparatus installed in Gakushu-in University. Using a synthesized single-crystal (0.04 × 0.04 × 0.03 mm3), high-pressure single-crystal X-ray diffraction measurements were conducted up to 7.4 GPa with synchrotron radiation. Lattice constants were determined at several pressure points up to 7.4 GPa. The isothermal bulk modulus of SUP-B-F, calculated from the Birch-Murnaghan Equation of State, was 154(2) GPa with a pressure derivative K'=4 (assuming). This value is significantly larger than that of super hydrous phase B (142.8(5) GPa with K"f=5.7 by Crichton et al., 1999). The X-ray reflection intensity data set was collected at 5.0 GPa using the four-circle diffractometer installed at the beam line BL-10A in Photon Factory, Japan. 198 reflections were used for structure refinement (the number of measured reflections is 786). After Lorentz- polarization correction and background reduction were applied for all intensity data, the crystallographic equivalent reflections (Orthorhombic, Pnnm) were averaged. Structure refinement results were R=5.0% and wR2=13.1%, respectively.

  14. Evaluation of various techniques for separation of non-polar modifier concentrates from petroleum waxy by-products

    Directory of Open Access Journals (Sweden)

    Fathi S. Soliman

    2014-09-01

    Full Text Available Two petroleum waxy by-products (light and middle slack wax crudes were evaluated for separation of non-polar modifiers by using different techniques. The results showed that, the light slack wax is selected as a suitable wax for separation of n-alkanes with even number of carbon atoms ranging from C20 to C26 for their high n-paraffin contents and can be used as non-polar structural modifiers. Different separation techniques; multistage fractional crystallization and liquid–solid chromatography; followed by the urea adduction technique have been used to separate non-polar modifier concentrates from the light slack wax crude. The light slack wax, its saturate components, the hard wax fractions isolated from light slack wax by the multistage fractional crystallization technique and their adducts were analyzed by GC to characterize and compare the produced components. The resulting data reveal that, the adducts of light slack wax and its saturate components; can be used as non-polar modifier concentrates of low carbon atoms (C20 + C22. From an economic point of view, the light slack wax adduct is selected as a non-polar modifier concentrate whereas, the separation step can be neglected to save energy. Meanwhile, the adduct of the hard wax isolated at 30 °C can be used as the preferable non-polar modifier concentrate of the high carbon number atoms (C24 + C26.

  15. Nonpolar and semipolar InGaN/GaN multiple-quantum-well solar cells with improved carrier collection efficiency

    Science.gov (United States)

    Huang, Xuanqi; Fu, Houqiang; Chen, Hong; Zhang, Xiaodong; Lu, Zhijian; Montes, Jossue; Iza, Michael; DenBaars, Steven P.; Nakamura, Shuji; Zhao, Yuji

    2017-04-01

    We demonstrate the nonpolar and semipolar InGaN/GaN multiple-quantum-well (MQW) solar cells grown on the nonpolar m-plane and semipolar ( 20 2 ¯ 1 ) plane bulk GaN substrates. The optical properties and photovoltaic performance of the nonpolar and semipolar InGaN solar cells were systematically studied, and the results were compared to the conventional polar c-plane devices. The absorption spectra, current density-voltage (J-V) characteristics, external quantum efficiency (EQE), and internal quantum efficiency (IQE) were measured for nonpolar m-plane, semipolar ( 20 2 ¯ 1 ) plane, and polar c-plane InGaN/GaN MQW solar cells. Nonpolar m-plane InGaN/GaN MQW solar cells showed the best performance across all devices, with a high open-circuit voltage of 2.32 V, a low bandgap-voltage offset of 0.59 V, and the highest EQE and IQE. In contrast, the polar c-plane device showed the lowest EQE despite the highest absorption spectra. This huge difference is attributed to the better carrier transport and collection on nonpolar m-plane devices due to the reduced polarization effects, which were further confirmed by bias-dependent EQE measurements and energy band diagram simulations. This study demonstrates the high potential of nonpolar and semipolar InGaN solar cells and can serve as guidance for the future design and fabrication of high efficiency III-nitride solar cells.

  16. In Vitro Anticancer Activity of a Nonpolar Fraction from Gynostemma pentaphyllum (Thunb.) Makino

    Science.gov (United States)

    Li, Yantao; Huang, Jiajun; Lin, Wanjun; Yuan, Zhongwen; Feng, Senling; Xie, Ying; Ma, Wenzhe

    2016-01-01

    Gynostemma pentaphyllum (Thunb.) Makino (GpM) has been widely used in traditional Chinese medicine (TCM) for the treatment of various diseases including cancer. Most previous studies have focused primarily on polar fractions of GpM for anticancer activities. In this study, a nonpolar fraction EA1.3A from GpM showed potent growth inhibitory activities against four cancer cell lines with IC50 ranging from 31.62 μg/mL to 38.02 μg/mL. Furthermore, EA1.3A also inhibited the growth of breast cancer cell MDA-MB-453 time-dependently, as well as its colony formation ability. EA1.3A induced apoptosis on MDA-MB-453 cells both dose-dependently and time-dependently as analyzed by flow cytometry and verified by western blotting analysis of apoptosis marker cleaved nuclear poly(ADP-ribose) polymerase (cPARP). Additionally, EA1.3A induced cell cycle arrest in G0/G1 phase. Chemical components analysis of EA1.3A by GC-MS revealed that this nonpolar fraction from GpM contains 10 compounds including four alkaloids, three organic esters, two terpenes, and one catechol substance, and all these compounds have not been reported in GpM. In summary, the nonpolar fraction EA1.3A from GpM inhibited cancer cell growth through induction of apoptosis and regulation of cell cycle progression. Our study shed light on new chemical bases for the anticancer activities of GpM and feasibilities to develop new anticancer agents from this widely used medicinal plant. PMID:27034692

  17. In Vitro Anticancer Activity of a Nonpolar Fraction from Gynostemma pentaphyllum (Thunb. Makino

    Directory of Open Access Journals (Sweden)

    Yantao Li

    2016-01-01

    Full Text Available Gynostemma pentaphyllum (Thunb. Makino (GpM has been widely used in traditional Chinese medicine (TCM for the treatment of various diseases including cancer. Most previous studies have focused primarily on polar fractions of GpM for anticancer activities. In this study, a nonpolar fraction EA1.3A from GpM showed potent growth inhibitory activities against four cancer cell lines with IC50 ranging from 31.62 μg/mL to 38.02 μg/mL. Furthermore, EA1.3A also inhibited the growth of breast cancer cell MDA-MB-453 time-dependently, as well as its colony formation ability. EA1.3A induced apoptosis on MDA-MB-453 cells both dose-dependently and time-dependently as analyzed by flow cytometry and verified by western blotting analysis of apoptosis marker cleaved nuclear poly(ADP-ribose polymerase (cPARP. Additionally, EA1.3A induced cell cycle arrest in G0/G1 phase. Chemical components analysis of EA1.3A by GC-MS revealed that this nonpolar fraction from GpM contains 10 compounds including four alkaloids, three organic esters, two terpenes, and one catechol substance, and all these compounds have not been reported in GpM. In summary, the nonpolar fraction EA1.3A from GpM inhibited cancer cell growth through induction of apoptosis and regulation of cell cycle progression. Our study shed light on new chemical bases for the anticancer activities of GpM and feasibilities to develop new anticancer agents from this widely used medicinal plant.

  18. Study on Surface Properties for Non-polar Fluids with Density Functional Theory

    Institute of Scientific and Technical Information of China (English)

    吴畏; 陆九芳; 付东; 刘金晨; 李以圭

    2004-01-01

    The density functional theory, simplified by the local density approximation and mean-field approximation, is applied to study the surface properties of pure non-polar fluids. A reasonable long rang correction is adopted to avoid the truncation of the potential. The perturbation theory is applied to establish the equation for the phase equilibrium, in which the hard-core chain fluid is as the reference fluid and the Yukawa potential is used as the perturbation term. Three parameters, elk, d and ms, are regressed from the vapor-liquid equilibria, and the surface properties, including density profile, surface tension and local surface tension profile are predicted with these parameters.

  19. A semiempirical model for estimating the hydration free energy of neutral nonpolar compounds

    Science.gov (United States)

    Ratkova, E. L.

    2012-10-01

    An improved semiempirical model for determining the hydration free energy of neutral nonpolar compounds is presented. The model is based on a combination of the RISM approach of the integral equation theory and empirical correlations. It is demonstrated that the developed model has high predictive ability for alkanes, alkenes, and dienes (present only in the test set of compounds). It is concluded that this semiempirical model can be applied in estimating the hydration free energy of more complicated structures based on saturated and nonsaturated aliphatic hydrocarbons.

  20. Storage lipids of yeasts: a survey of nonpolar lipid metabolism in Saccharomyces cerevisiae, Pichia pastoris, and Yarrowia lipolytica.

    Science.gov (United States)

    Koch, Barbara; Schmidt, Claudia; Daum, Günther

    2014-09-01

    Biosynthesis and storage of nonpolar lipids, such as triacylglycerols (TG) and steryl esters (SE), have gained much interest during the last decades because defects in these processes are related to severe human diseases. The baker's yeast Saccharomyces cerevisiae has become a valuable tool to study eukaryotic lipid metabolism because this single-cell microorganism harbors many enzymes and pathways with counterparts in mammalian cells. In this article, we will review aspects of TG and SE metabolism and turnover in the yeast that have been known for a long time and combine them with new perceptions of nonpolar lipid research. We will provide a detailed insight into the mechanisms of nonpolar lipid synthesis, storage, mobilization, and degradation in the yeast S. cerevisiae. The central role of lipid droplets (LD) in these processes will be addressed with emphasis on the prevailing view that this compartment is more than only a depot for TG and SE. Dynamic and interactive aspects of LD with other organelles will be discussed. Results obtained with S. cerevisiae will be complemented by recent investigations of nonpolar lipid research with Yarrowia lipolytica and Pichia pastoris. Altogether, this review article provides a comprehensive view of nonpolar lipid research in yeast.

  1. Media education.

    Science.gov (United States)

    Strasburger, Victor C

    2010-11-01

    The American Academy of Pediatrics recognizes that exposure to mass media (eg, television, movies, video and computer games, the Internet, music lyrics and videos, newspapers, magazines, books, advertising) presents health risks for children and adolescents but can provide benefits as well. Media education has the potential to reduce the harmful effects of media and accentuate the positive effects. By understanding and supporting media education, pediatricians can play an important role in reducing harmful effects of media on children and adolescents.

  2. Determination of vapor pressures for nonpolar and semipolar organic compounds from gas chromatographic retention data

    Science.gov (United States)

    Hinckley, D.A.; Bidleman, T.F.; Foreman, W.T.; Tuschall, J.R.

    1990-01-01

    Vapor pressures for nonpolar and moderately polar organochlorine, pyrethroid, and organophosphate insecticides, phthalate esters, and organophosphate flame retardants were determined by capillary gas chromatography (GC). Organochlorines and polycyclic aromatic hydrocarbons with known liquid-phase vapor pressures (P??L) (standard compounds) were chromatographed along with two reference compounds n-C20 (elcosane) and p,p???-DDT on a 1.0-m-long poly(dimethylsiloxane) bonded-phase (BP-1) column to determine their vapor pressures by GC (P??GC). A plot of log P??L vs log P??GC for standard compounds was made to establish a correlation between measured and literature values, and this correlation was then used to compute P??L of test compounds from their measured P??GC. P??L of seven major components of technical chlordane, endosulfan and its metabolites, ??-hexachlorocyclohexane, mirex, and two components of technical toxaphene were determined by GC. This method provides vapor pressures within a factor of 2 of average literature values for nonpolar compounds, similar to reported interlaboratory precisions of vapor pressure determinations. GC tends to overestimate vapor pressures of moderately polar compounds. ?? 1990 American Chemical Society.

  3. A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces.

    Science.gov (United States)

    Yu, Liping; Zunger, Alex

    2014-10-13

    The discovery of conductivity and magnetism at the polar-nonpolar interfaces of insulating nonmagnetic oxides such as LaAlO3 and SrTiO3 has raised prospects for attaining interfacial functionalities absent in the component materials. Yet, the microscopic origin of such emergent phenomena remains unclear, posing obstacles to design of improved functionalities. Here we present first principles calculations of electronic and defect properties of LaAlO3/SrTiO3 interfaces and reveal a unifying mechanism for the origins of both conductivity and magnetism. We demonstrate that the polar discontinuity across the interface triggers thermodynamically the spontaneous formation of certain defects that in turn cancel the polar field induced by the polar discontinuity. The ionization of the spontaneously formed surface oxygen vacancy defects leads to interface conductivity, whereas the unionized Ti-on-Al antisite defects lead to interface magnetism. The proposed mechanism suggests practical design principles for inducing and controlling both conductivity and magnetism at general polar-nonpolar interfaces.

  4. Nonpolar III-nitride vertical-cavity surface-emitting lasers incorporating an ion implanted aperture

    KAUST Repository

    Leonard, J. T.

    2015-07-06

    © 2015 AIP Publishing LLC. We report on our recent progress in improving the performance of nonpolar III-nitride vertical-cavity surface-emitting lasers (VCSELs) by using an Al ion implanted aperture and employing a multi-layer electron-beam evaporated ITO intracavity contact. The use of an ion implanted aperture improves the lateral confinement over SiNx apertures by enabling a planar ITO design, while the multi-layer ITO contact minimizes scattering losses due to its epitaxially smooth morphology. The reported VCSEL has 10 QWs, with a 3nm quantum well width, 1nm barriers, a 5nm electron-blocking layer, and a 6.95- λ total cavity thickness. These advances yield a single longitudinal mode 406nm nonpolar VCSEL with a low threshold current density (∼16kA/cm2), a peak output power of ∼12μW, and a 100% polarization ratio. The lasing in the current aperture is observed to be spatially non-uniform, which is likely a result of filamentation caused by non-uniform current spreading, lateral optical confinement, contact resistance, and absorption loss.

  5. Nonpolar III-nitride vertical-cavity surface-emitting lasers incorporating an ion implanted aperture

    Science.gov (United States)

    Leonard, J. T.; Cohen, D. A.; Yonkee, B. P.; Farrell, R. M.; Margalith, T.; Lee, S.; DenBaars, S. P.; Speck, J. S.; Nakamura, S.

    2015-07-01

    We report on our recent progress in improving the performance of nonpolar III-nitride vertical-cavity surface-emitting lasers (VCSELs) by using an Al ion implanted aperture and employing a multi-layer electron-beam evaporated ITO intracavity contact. The use of an ion implanted aperture improves the lateral confinement over SiNx apertures by enabling a planar ITO design, while the multi-layer ITO contact minimizes scattering losses due to its epitaxially smooth morphology. The reported VCSEL has 10 QWs, with a 3 nm quantum well width, 1 nm barriers, a 5 nm electron-blocking layer, and a 6.95- λ total cavity thickness. These advances yield a single longitudinal mode 406 nm nonpolar VCSEL with a low threshold current density (˜16 kA/cm2), a peak output power of ˜12 μW, and a 100% polarization ratio. The lasing in the current aperture is observed to be spatially non-uniform, which is likely a result of filamentation caused by non-uniform current spreading, lateral optical confinement, contact resistance, and absorption loss.

  6. Characterizations of nonlinear optical properties on GaN crystals in polar, nonpolar, and semipolar orientations

    Science.gov (United States)

    Chen, Hong; Huang, Xuanqi; Fu, Houqiang; Lu, Zhijian; Zhang, Xiaodong; Montes, Jossue A.; Zhao, Yuji

    2017-05-01

    We report the basic nonlinear optical properties, namely, two-photon absorption coefficient ( β ), three-photon absorption coefficient ( γ ), and Kerr nonlinear refractive index ( n kerr), of GaN crystals in polar c-plane, nonpolar m-plane, and semipolar ( 20 21 ¯ ) plane orientations. A typical Z-scan technique was used for the measurement with a femtosecond Ti:S laser from wavelengths of 724 nm to 840 nm. For the two-photon absorption coefficient ( β ), similar values were obtained for polar, nonpolar, and semipolar samples, which are characterized to be ˜0.90 cm/GW at 724 nm and ˜0.65 cm/GW at 730 nm for all the three samples. For the Kerr nonlinear refractive index ( n kerr), self-focusing features were observed in this work, which is different from previous reports where self-defocusing features were observed on GaN in the visible and near-UV spectral regions. At 724 nm, n kerr was measured to be ˜2.5 0 × 10 - 14 cm 2 / W for all three samples. Three-photon absorption coefficients ( γ ) were also determined, which were found to be consistent with previous reports. This study provides valuable information on the basic nonlinear optical properties of III-nitride semiconductors, which are vital for a wide range of applications such as integrated photonics and quantum photonics.

  7. Non-Polar Natural Products from Bromelia laciniosa, Neoglaziovia variegata and Encholirium spectabile (Bromeliaceae

    Directory of Open Access Journals (Sweden)

    Ole Johan Juvik

    2017-09-01

    Full Text Available Extensive regional droughts are already a major problem on all inhabited continents and severe regional droughts are expected to become an increasing and extended problem in the future. Consequently, extended use of available drought resistant food plants should be encouraged. Bromelia laciniosa, Neoglaziovia variegata and Encholirium spectabile are excellent candidates in that respect because they are established drought resistant edible plants from the semi-arid Caatinga region. From a food safety perspective, increased utilization of these plants would necessitate detailed knowledge about their chemical constituents. However, their chemical compositions have previously not been determined. For the first time, the non-polar constituents of B. laciniosa, N. variegata and E. spectabile have been identified. This is the first thorough report on natural products from N. variegata, E. spectabile, and B. laciniosa. Altogether, 20 non-polar natural products were characterized. The identifications were based on hyphenated gas chromatography-high resolution mass spectrometry (GC-HRMS and supported by 1D and 2D Nuclear Magnetic Resonance (NMR plant metabolomics.

  8. Dermoscopic features of basal cell carcinomas: differences in appearance under non-polarized and polarized light.

    Science.gov (United States)

    Liebman, Tracey N; Jaimes-Lopez, Natalia; Balagula, Yevgeniy; Rabinovitz, Harold S; Wang, Steven Q; Dusza, Stephen W; Marghoob, Ashfaq A

    2012-03-01

    Basal cell carcinomas (BCCs) can be diagnosed using different dermoscopic modalities. To evaluate dermoscopic features of BCCs using nonpolarized and polarized dermoscopy to highlight similarities and differences between dermoscopic modalities. Retrospective study of 149 BCCs under nonpolarized dermoscopy (NPD), polarized contact dermoscopy (PCD), and polarized noncontact dermoscopy (PNCD). Images were evaluated for a range of dermoscopic colors, structures, and vessels. Features were compared according to histopathologic subtype. The most common dermoscopic structures in BCCs across all modalities included globules (50.3-51.0%), dots (49.7-50.3%), white structureless areas (63.1-74.5%), structureless gray-brown areas (24.2-24.8%), and ulcerations (28.2%). The most frequently observed vasculature included arborizing vessels (18.8-38.3%), short fine telangiectasias (SFTs) (73.8-82.6%), and vascular blush (41.6-83.2%). Structures with higher levels of agreement across modalities included pigmented structures and ulcerations. Lower levels of agreement existed between contact and noncontact modalities for certain vascular features. White shiny structures, which include shiny white lines (chrysalis and crystalline structures) (0-69.1%), shiny white areas (0-25.5%), and rosettes (0-11.4%), exhibited no agreement between NPD and polarized modalities. This study highlights differences in dermoscopic features of BCCs under three dermoscopic modalities. Shiny white lines (chrysalis and crystalline structures) and shiny white areas may be used as additional criteria to diagnose BCCs. © 2011 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

  9. High indium non-polar InGaN clusters with infrared sensitivity grown by PAMBE

    Directory of Open Access Journals (Sweden)

    Shruti Mukundan

    2015-03-01

    Full Text Available Studies on the optical properties of InGaN alloy of relatively higher indium content are of potential interest to understand the effect of indium content on the optical band gap of epitaxial InGaN. We report the growth of self assembled non-polar high indium clusters of In0.55Ga0.45N over non-polar (11-20 a-plane In0.17Ga0.83N epilayer grown on a-plane (11-20GaN/(1-102 r-plane sapphire substrate using plasma assisted molecular beam epitaxy (PAMBE. Such structures are potential candidates for high brightness LEDs emitting in longer wavelengths. The high resolution X-ray diffraction studies revealed the formation of two distinct compositions of InxGa1−xN alloys, which were further confirmed by photoluminescence studies. A possible mechanism for the formation of such structure was postulated which was supported with the results obtained by energy dispersive X-ray analysis. The structure hence grown when investigated for photo-detecting properties, showed sensitivity to both infrared and ultraviolet radiations due to the different composition of InGaN region.

  10. Morphological, structural and electrical investigations on non-polar a-plane ZnO epilayers

    Science.gov (United States)

    Lautenschlaeger, Stefan; Eisermann, Sebastian; Hofmann, Michael N.; Roemer, Udo; Pinnisch, Melanie; Laufer, Andreas; Meyer, Bruno K.; von Wenckstern, Holger; Lajn, Alexander; Schmidt, Florian; Grundmann, Marius; Blaesing, Juergen; Krost, Alois

    2010-07-01

    We report on the growth of non-polar a-plane ZnO by CVD on r-plane-sapphire-wafers, a-plane GaN-templates and a-plane ZnO single-crystal substrates. Only the homoepitaxial growth approach leads to a Frank-van-der-Merwe growth mode, as shown by atomic force microscopy. The X-ray-diffraction spectra of the homoepitaxial thin films mirror the excellent crystalline quality of the ZnO substrate. The morphological and the structural quality of the homoepitaxial films is comparable to the best results for the growth on c-plane ZnO-substrates. The impurity incorporation, especially of group III elements, seems to be reduced when growing on the non-polar a-plane surface compared to the c-plane films as demonstrated by secondary ion mass spectrometry (SIMS). Optical properties have been investigated using low temperature photoluminescence measurements. We employed capacitance-voltage measurements ( C- V) to measure the background carrier density and its profile from substrate/film interface throughout the film to the surface. In thermal admittance spectroscopy (TAS) specific traps could be distinguished, and their thermal activation energies and capture cross sections could be determined.

  11. High indium non-polar InGaN clusters with infrared sensitivity grown by PAMBE

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Shruti; Mohan, Lokesh; Chandan, Greeshma; Krupanidhi, S. B., E-mail: sbk@mrc.iisc.ernet.in; Shinde, Satish; Nanda, K. K. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Roul, Basanta [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India); Maiti, R.; Ray, S. K. [Department of Physics, Indian Institute of Technology, Kharagpur (India)

    2015-03-15

    Studies on the optical properties of InGaN alloy of relatively higher indium content are of potential interest to understand the effect of indium content on the optical band gap of epitaxial InGaN. We report the growth of self assembled non-polar high indium clusters of In{sub 0.55}Ga{sub 0.45}N over non-polar (11-20) a-plane In{sub 0.17}Ga{sub 0.83}N epilayer grown on a-plane (11-20)GaN/(1-102) r-plane sapphire substrate using plasma assisted molecular beam epitaxy (PAMBE). Such structures are potential candidates for high brightness LEDs emitting in longer wavelengths. The high resolution X-ray diffraction studies revealed the formation of two distinct compositions of In{sub x}Ga{sub 1−x}N alloys, which were further confirmed by photoluminescence studies. A possible mechanism for the formation of such structure was postulated which was supported with the results obtained by energy dispersive X-ray analysis. The structure hence grown when investigated for photo-detecting properties, showed sensitivity to both infrared and ultraviolet radiations due to the different composition of InGaN region.

  12. Media Pedagogy: Media Education, Media Socialisation and Educational Media

    Directory of Open Access Journals (Sweden)

    Lars Qvortrup

    2007-07-01

    Full Text Available The aim of this paper is to examine the relationship between education and media. These two concepts can be combined in three ways: one can think of media education, i.e. education in the subject of mass media. One can think of media socialisation, i.e. education within the context of a media society in which pupils and students are experienced media users. Finally, one can think of educational media, i.e. media used for educational purposes.After having specified these three subject areas, the paper focuses on the third subject: Media used for educational purposes. According to the paper teaching can be defined as a specialised form of communication, and the basic point of the paper is that all communication is mediated. One cannot talk about such a thing as “non-mediated” communication. Also talking or touching implies media: Language or body language.Consequently, the introduction of new, digital media for teaching does not imply to make teaching more artificial or non-authentic. The introduction of new, digital media for teaching implies that other and older educational media are re-mediated.

  13. Media Komunitas dan Media Literacy

    Directory of Open Access Journals (Sweden)

    Pawito .

    2013-12-01

    Full Text Available Abstract:This essay deals with community media in relation to media literacy. After a short discussion on a number of community media characters is made the essay goes further with somewhat detail theoretical presumptions of the roles of media community with respect primarily to the development as Amartya Sen mentioned about. The author suggests that community media may play some significant roles in the development including (a disseminating information (from varieties of perspective, (b facilitating public discussion, (c helping to reach solutions of problems, (d encouraging participations, and (e encouraging the development of media literacy. Regarding the last point the author remarks that media community may have a dual-roles i.e facilitating community’s member in media participation and facilitating community’s member in media education.

  14. Media violence.

    Science.gov (United States)

    Strasburger, V C

    1999-01-01

    For decades, media violence has been viewed as largely a Western problem. New studies indicate that Indian children have increasing access to the media and that media violence will subject them to the same problems as Western children: imitation, desensitization, fear, and inappropriate attitudes about violence and aggression. Solutions exist but will have to be implemented within the next decade to protect Indian children and adolescents from the harmful effects of media violence.

  15. Role of the electronegativity for the interface properties of non-polar heterostructures

    KAUST Repository

    Nazir, Safdar

    2012-04-01

    Density functional theory is used to investigate the interfaces in the non-polar ATiO 3/SrTiO 3 (A=Pb, Ca, Ba) heterostructures. All TiO 2-terminated interfaces show an insulating behavior. By reduction of the O content in the AO, SrO, and TiO 2 layers, metallic interface states develop, due to the occupation of the Ti 3d orbitals. For PbTiO 3/SrTiO 3, the Pb 6p states cross the Fermi energy. O vacancy formation energies depend strictly on the electronegativity and the effective volume of the A ion, while the main characteristics of the interface electronic states are maintained. © Europhysics Letters Association, 2012.

  16. Homoepitaxial HVPE-GaN growth on non-polar and semi-polar seeds

    Science.gov (United States)

    Amilusik, M.; Sochacki, T.; Lucznik, B.; Fijalkowski, M.; Smalc-Koziorowska, J.; Weyher, J. L.; Teisseyre, H.; Sadovyi, B.; Bockowski, M.; Grzegory, I.

    2014-10-01

    In this work homoepitaxial HVPE-GaN growth on non-polar and semi-polar GaN seeds was described. Two crystallization processes, in the same experimental conditions but using different carrier gases: N2 and H2, were performed. An influence of growth directions and growth conditions on the growth rate and properties (morphology, structural quality and oxygen and silicon contaminations) of obtained crystals were investigated and discussed. It was shown that the growth rate strongly depends on the growth direction and the carrier gas. It was demonstrated that for the semi-polar [20-21] direction it was possible to obtain high quality and highly conductive (without intentional doping) gallium nitride layers.

  17. ADSORPTION OF LATERALLY INTERACTING 1-NAPHTHOL/1-NAPHTHYL AMINE MIXTURES ON NONPOLAR SURFACES FROM AQUEOUS SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    Wei-ming Zhang; Jin-long Chen; Qun Chen; Ming-yang He; Bing-cai Pan; Quan-xing Zhang

    2006-01-01

    The binary adsorption behavior of 1-naphthol/1-naphthylamine mixtures in water on nonpolar adsorbent Amberlite XAD4 was investigated at 293 K, 303 K and 313 K, respectively. The experimental uptakes of 1-naphthol and 1-naphthylamine in all binary-component systems of different molar ratios were obviously higher than the corresponding uptakes predicted by the extended Langmuir model, assuming no interaction between the adsorbed molecules of the two components. This phenomenon was attributed to the cooperative adsorption effect arising from the hydrogen bonding interaction between 1-naphthol and 1-naphthylamine molecules. A modified extended Langmuir model was proposed to describe the binary adsorption behavior by means of introducing a fitting parameter related with the cooperative adsorption effect of the adsorbates.

  18. Variability of non-polar secondary metabolites in the red alga Portieria.

    Science.gov (United States)

    Payo, Dioli Ann; Colo, Joannamel; Calumpong, Hilconida; de Clerck, Olivier

    2011-01-01

    Possible sources of variation in non-polar secondary metabolites of Portieria hornemannii, sampled from two distinct regions in the Philippines (Batanes and Visayas), resulting from different life-history stages, presence of cryptic species, and/or spatiotemporal factors, were investigated. PCA analyses demonstrated secondary metabolite variation between, as well as within, five cryptic Batanes species. Intraspecific variation was even more pronounced in the three cryptic Visayas species, which included samples from six sites. Neither species groupings, nor spatial or temporal based patterns, were observed in the PCA analysis, however, intraspecific variation in secondary metabolites was detected between life-history stages. Male gametophytes (102 metabolites detected) were strongly discriminated from the two other stages, whilst female gametophyte (202 metabolites detected) and tetrasporophyte (106 metabolites detected) samples were partially discriminated. These results suggest that life-history driven variations, and possibly other microscale factors, may influence the variation within Portieria species.

  19. Variability of Non-Polar Secondary Metabolites in the Red Alga Portieria

    Directory of Open Access Journals (Sweden)

    Olivier de Clerck

    2011-11-01

    Full Text Available Possible sources of variation in non-polar secondary metabolites of Portieria hornemannii, sampled from two distinct regions in the Philippines (Batanes and Visayas, resulting from different life-history stages, presence of cryptic species, and/or spatiotemporal factors, were investigated. PCA analyses demonstrated secondary metabolite variation between, as well as within, five cryptic Batanes species. Intraspecific variation was even more pronounced in the three cryptic Visayas species, which included samples from six sites. Neither species groupings, nor spatial or temporal based patterns, were observed in the PCA analysis, however, intraspecific variation in secondary metabolites was detected between life-history stages. Male gametophytes (102 metabolites detected were strongly discriminated from the two other stages, whilst female gametophyte (202 metabolites detected and tetrasporophyte (106 metabolites detected samples were partially discriminated. These results suggest that life-history driven variations, and possibly other microscale factors, may influence the variation within Portieria species.

  20. On the rotational energy distributions of reactive, non-polar species in the interstellar medium

    CERN Document Server

    Glinski, Robert J; Downum, Clark R

    2013-01-01

    A basic model for the formation of non-equilibrium rotational energy distributions is described for reactive, homo-polar diatomic molecules and ions in the interstellar medium. Kinetic models were constructed to calculate the rotational populations of C2+ under the conditions it would experience in the diffuse interstellar medium. As the non-polar ion reacts with molecular hydrogen, but not atomic hydrogen, the thermalization of a hot nascent rotational population will be arrested by chemical reaction when the H2 density begins to be significant. Populations that deviate strongly from the local thermodynamic equilibrium are predicted for C2+ in environments where it may be detectable. Consequences of this are discussed and a new optical spectrum is calculated.

  1. Dynamics of electric field induced particle alignment in nonpolar polymer matrix

    Science.gov (United States)

    Tai, Xiangyang; Wu, Guozhang; Yui, Hiroshi; Asai, Shigeo; Sumita, Masao

    2003-11-01

    The dynamics of electric field induced particle alignment in nonpolar polymer matrix to build one-dimensional conductive materials was investigated. The influence of electric field on particle alignment was real-time traced by dynamic percolation measurement using carbon black (CB) filled polyethylene as a model system. The activation energy of the continuous CB path formation was calculated and found to be unchanged with CB alignment. The critical percolation concentration at thermodynamic equilibrium state φc* was deduced to characterize the anisotropism of network structure, by which the thermodynamic prerequisite electric field E* for the transition from three-dimensional isotropic network to one-dimensional chain could be easily found out.

  2. Chronic toxicity and body residues of the nonpolar narcotic 1,2,3,4-tetrachrlorobenzene in Chironomus riparius

    NARCIS (Netherlands)

    Leslie, H.A.; Kraak, M.H.S.; Hermens, J.L.

    2004-01-01

    The use of internal concentrations as a dose parameter for baseline toxicity requires an understanding of the relationship between accumulation level and toxic effects, not only for acute but also for chronic exposure. In this study of chronic toxicity of the nonpolar narcotic 1,2,3,4-tetrachloroben

  3. Chronic toxicity and body residues of the nonpolar narcotic 1,2,3,4-tetrachrlorobenzene in Chironomus riparius

    NARCIS (Netherlands)

    Leslie, H.A.; Kraak, M.H.S.; Hermens, J.L.

    2004-01-01

    The use of internal concentrations as a dose parameter for baseline toxicity requires an understanding of the relationship between accumulation level and toxic effects, not only for acute but also for chronic exposure. In this study of chronic toxicity of the nonpolar narcotic

  4. Evaluation of Extraction Protocols for Simultaneous Polar and Non-Polar Yeast Metabolite Analysis Using Multivariate Projection Methods

    Directory of Open Access Journals (Sweden)

    Nicolas P. Tambellini

    2013-07-01

    Full Text Available Metabolomic and lipidomic approaches aim to measure metabolites or lipids in the cell. Metabolite extraction is a key step in obtaining useful and reliable data for successful metabolite studies. Significant efforts have been made to identify the optimal extraction protocol for various platforms and biological systems, for both polar and non-polar metabolites. Here we report an approach utilizing chemoinformatics for systematic comparison of protocols to extract both from a single sample of the model yeast organism Saccharomyces cerevisiae. Three chloroform/methanol/water partitioning based extraction protocols found in literature were evaluated for their effectiveness at reproducibly extracting both polar and non-polar metabolites. Fatty acid methyl esters and methoxyamine/trimethylsilyl derivatized aqueous compounds were analyzed by gas chromatography mass spectrometry to evaluate non-polar or polar metabolite analysis. The comparative breadth and amount of recovered metabolites was evaluated using multivariate projection methods. This approach identified an optimal protocol consisting of 64 identified polar metabolites from 105 ion hits and 12 fatty acids recovered, and will potentially attenuate the error and variation associated with combining metabolite profiles from different samples for untargeted analysis with both polar and non-polar analytes. It also confirmed the value of using multivariate projection methods to compare established extraction protocols.

  5. Effect of the alkyl chain length on the rotational dynamics of nonpolar and dipolar solutes in a series of N-alkyl-N-methylmorpholinium ionic liquids.

    Science.gov (United States)

    Khara, Dinesh Chandra; Kumar, Jaini Praveen; Mondal, Navendu; Samanta, Anunay

    2013-05-01

    Rotational dynamics of two dipolar solutes, 4-aminophthalimide (AP) and 6-propionyl-2-dimethylaminonaphthalene (PRODAN), and a nonpolar solute, anthracene, have been studied in N-alkyl-N-methylmorpholinium (alkyl = ethyl, butyl, hexyl, and octyl) bis(trifluoromethansulfonyl)imide (Tf2N) ionic liquids as a function of temperature and excitation wavelength to probe the microheterogeneous nature of these ionic liquids, which are recently reported to be more structured than the imidazolium ionic liquids (Khara and Samanta, J. Phys. Chem. B2012, 116, 13430-13438). Analysis of the measured rotational time constants of the solutes in terms of the Stokes-Einstein-Debye (SED) hydrodynamic theory reveals that with increase in the alkyl chain length attached to the cationic component of the ionic liquids, AP shows stick to superstick behavior, PRODAN rotation lies between stick and slip boundary conditions, whereas anthracene exhibits slip to sub slip behavior. The contrasting rotational dynamics of these probe molecules is a reflection of their location in distinct environments of the ionic liquids thus demonstrating the heterogeneity of these ionic liquids. The microheterogeneity of these media, in particular, those with the long alkyl chain, is further evidence from the excitation wavelength dependence study of the rotational diffusion of the dipolar probe molecules.

  6. Media Technology

    Directory of Open Access Journals (Sweden)

    Zhou Gang

    2016-01-01

    Full Text Available Modern colleges are faced with the dual pressures of university reform and international competition, how to overcome difficulties, to play the role of modern English teaching in colleges and colleges to enhance the core competitiveness of colleges, colleges and colleges modern English teaching problems to be solved. Based on the current situation of modern colleges in the premise of the Modern media platform fully demonstrated the characteristics and viability of the Modern media English teaching, the necessity of modern English teaching of college Modern media. Discusses the Modern media targeting English teaching and important role is in the English teaching to guide the development of modern colleges modern media.

  7. Non-polar lipids accumulate during storage of transfusion products and do not contribute to the onset of transfusion-related acute lung injury.

    Science.gov (United States)

    Peters, A L; Vervaart, M A T; van Bruggen, R; de Korte, D; Nieuwland, R; Kulik, W; Vlaar, A P J

    2017-01-01

    The accumulation of non-polar lipids arachidonic acid, 5-hydroxyeicosatetraenoic acid (HETE), 12-HETE and 15-HETE during storage of transfusion products may play a role in the onset of transfusion-related acute lung injury (TRALI), a syndrome of respiratory distress after transfusion. We investigated non-polar lipid accumulation in red blood cells (RBCs) stored for 42 days, plasma stored for 7 days at either 4 or 20°C and platelet (PLT) transfusion products stored for 7 days. Furthermore, we investigated whether transfusion of RBCs with increased levels of non-polar lipids induces TRALI in a 'two-hit' human volunteer model. All products were produced following Dutch Blood Bank protocols and are according to European standards. Non-polar lipids were measured with high-performance liquid chromotography followed by mass spectrometry. All non-polar lipids increased in RBCs after 21 days of storage compared to baseline. The non-polar lipid concentration in plasma increased significantly, and the increase was even more pronounced in products stored at 20°C. In platelets, baseline levels of 5-HETE and 15-HETE were higher than in RBCs or plasma. However, the non-polar lipids did not change significantly during storage of PLT products. Infusion of RBCs with increased levels of non-polar lipids did not induce TRALI in LPS-primed human volunteers. We conclude that non-polar lipids accumulate in RBC and plasma transfusion products and that accumulation is temperature dependent. Accumulation of non-polar lipids does not appear to explain the onset of TRALI (Dutch Trial Register - NTR4455). © 2016 International Society of Blood Transfusion.

  8. Automatic parametrization of non-polar implicit solvent models for the blind prediction of solvation free energies

    Science.gov (United States)

    Wang, Bao; Zhao, Zhixiong; Wei, Guo-Wei

    2016-09-01

    In this work, a systematic protocol is proposed to automatically parametrize the non-polar part of implicit solvent models with polar and non-polar components. The proposed protocol utilizes either the classical Poisson model or the Kohn-Sham density functional theory based polarizable Poisson model for modeling polar solvation free energies. Four sets of radius parameters are combined with four sets of charge force fields to arrive at a total of 16 different parametrizations for the polar component. For the non-polar component, either the standard model of surface area, molecular volume, and van der Waals interactions or a model with atomic surface areas and molecular volume is employed. To automatically parametrize a non-polar model, we develop scoring and ranking algorithms to classify solute molecules. The their non-polar parametrization is obtained based on the assumption that similar molecules have similar parametrizations. A large database with 668 experimental data is collected and employed to validate the proposed protocol. The lowest leave-one-out root mean square (RMS) error for the database is 1.33 kcal/mol. Additionally, five subsets of the database, i.e., SAMPL0-SAMPL4, are employed to further demonstrate that the proposed protocol. The optimal RMS errors are 0.93, 2.82, 1.90, 0.78, and 1.03 kcal/mol, respectively, for SAMPL0, SAMPL1, SAMPL2, SAMPL3, and SAMPL4 test sets. The corresponding RMS errors for the polarizable Poisson model with the Amber Bondi radii are 0.93, 2.89, 1.90, 1.16, and 1.07 kcal/mol, respectively.

  9. Media Flow

    DEFF Research Database (Denmark)

    Kabel, Lars

    2016-01-01

    News and other kinds of journalistic stories, 16-17 hours a day, all year round, on all platforms, also the moderated social media. The key research thesis behind this article is that the continuous and speedy stream of news stories and media content now is becoming the centre of the production...... processes and the value creation in converged multimedia newsrooms. The article identify new methods and discuss editorial challenges in handling media flow....

  10. Mass Media

    Institute of Scientific and Technical Information of China (English)

    叶全荣

    2006-01-01

    @@ Every day,we are all influenced by the mass media.Although some critics of the media claim that these means of communication are used mainly to control our thinking and get us to buy products that we don't need,the media also contribute to keeping people informed.In other words,while dangers do exist,the benefits of the media far outweigh(超过)the disadvantages.Most of the messages brought to viewers,listeners,and readers are designed either to inform or to entertain,and neither of these goals can be considered dangerous or harmful.

  11. Heme and non-heme iron transporters in non-polarized and polarized cells

    Directory of Open Access Journals (Sweden)

    Yasui Yumiko

    2010-06-01

    Full Text Available Abstract Background Heme and non-heme iron from diet, and recycled iron from hemoglobin are important products of the synthesis of iron-containing molecules. In excess, iron is potentially toxic because it can produce reactive oxygen species through the Fenton reaction. Humans can absorb, transport, store, and recycle iron without an excretory system to remove excess iron. Two candidate heme transporters and two iron transporters have been reported thus far. Heme incorporated into cells is degraded by heme oxygenases (HOs, and the iron product is reutilized by the body. To specify the processes of heme uptake and degradation, and the reutilization of iron, we determined the subcellular localizations of these transporters and HOs. Results In this study, we analyzed the subcellular localizations of 2 isoenzymes of HOs, 4 isoforms of divalent metal transporter 1 (DMT1, and 2 candidate heme transporters--heme carrier protein 1 (HCP1 and heme responsive gene-1 (HRG-1--in non-polarized and polarized cells. In non-polarized cells, HCP1, HRG-1, and DMT1A-I are located in the plasma membrane. In polarized cells, they show distinct localizations: HCP1 and DMT1A-I are located in the apical membrane, whereas HRG-1 is located in the basolateral membrane and lysosome. 16Leu at DMT1A-I N-terminal cytosolic domain was found to be crucial for plasma membrane localization. HOs are located in smooth endoplasmic reticulum and colocalize with NADPH-cytochrome P450 reductase. Conclusions HCP1 and DMT1A-I are localized to the apical membrane, and HRG-1 to the basolateral membrane and lysosome. These findings suggest that HCP1 and DMT1A-I have functions in the uptake of dietary heme and non-heme iron. HRG-1 can transport endocytosed heme from the lysosome into the cytosol. These localization studies support a model in which cytosolic heme can be degraded by HOs, and the resulting iron is exported into tissue fluids via the iron transporter ferroportin 1, which is

  12. Nonpolarized signaling reveals two distinct modes of 3D cell migration.

    Science.gov (United States)

    Petrie, Ryan J; Gavara, Núria; Chadwick, Richard S; Yamada, Kenneth M

    2012-04-30

    We search in this paper for context-specific modes of three-dimensional (3D) cell migration using imaging for phosphatidylinositol (3,4,5)-trisphosphate (PIP3) and active Rac1 and Cdc42 in primary fibroblasts migrating within different 3D environments. In 3D collagen, PIP3 and active Rac1 and Cdc42 were targeted to the leading edge, consistent with lamellipodia-based migration. In contrast, elongated cells migrating inside dermal explants and the cell-derived matrix (CDM) formed blunt, cylindrical protrusions, termed lobopodia, and Rac1, Cdc42, and PIP3 signaling was nonpolarized. Reducing RhoA, Rho-associated protein kinase (ROCK), or myosin II activity switched the cells to lamellipodia-based 3D migration. These modes of 3D migration were regulated by matrix physical properties. Specifically, experimentally modifying the elasticity of the CDM or collagen gels established that nonlinear elasticity supported lamellipodia-based migration, whereas linear elasticity switched cells to lobopodia-based migration. Thus, the relative polarization of intracellular signaling identifies two distinct modes of 3D cell migration governed intrinsically by RhoA, ROCK, and myosin II and extrinsically by the elastic behavior of the 3D extracellular matrix.

  13. Optical Kerr Effect Spectroscopy of a Nonpolar Solute in Dicationic versus Monocationic Ionic Liquids

    Science.gov (United States)

    Gurung, Eshan; Xue, Lianjie; Tamas, George; Quitevis, Edward

    2014-03-01

    A comparison of the intermolecular dynamics of small nonpolar solute molecules in monocationic and dicationic ionic liquids (ILs) was performed using optical heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES). The optical Kerr effect (OKE) spectrum of CS2 in 1-methyl-3-propylimidazolium bis(trifluoromethane-sulfonyl)amide [C3mim][NTf2] and 1,6-bis(3-methylimidazolium-1-yl) hexane bis(trifluoromethane-sulfonyl)amide [C6(mim)2][NTf2]2 was investigated as a function of concentration at 295 K. An additivity model with components from the subpicosecond dynamics of IL and CS2 was used to interpret the OKE spectra of the mixtures. The spectrum of CS2 in the two ILs is lower in frequency and narrower than that of neat CS2. The spectrum of CS2 in the dicationic IL is higher in frequency than in the monocationic IL. This result shows that CS2 molecule experiences a stiffer potential in dicationic ILs as compared to monocationic ILs. Higher stiffness in C6(mim)2][NTf2]2 might be due to a more ordered arrangement and lower mobility of the alkyl chains linking the imidazolium rings. This work was supported by NSF Grant CHE-1153077.

  14. Effects of polar and nonpolar groups on the solubility of organic compounds in soil organic matter

    Science.gov (United States)

    Chiou, C.T.; Kile, D.E.

    1994-01-01

    Vapor sorption capacities on a high-organic-content peat, a model for soil organic matter (SOM), were determined at room temperature for the following liquids: n-hexane, 1,4-dioxane, nitroethane, acetone, acetonitrile, 1-propanol, ethanol, and methanol. The linear organic vapor sorption is in keeping with the dominance of vapor partition in peat SOM. These data and similar results of carbon tetrachloride (CT), trichloroethylene (TCE), benzene, ethylene glycol monoethyl ether (EGME), and water on the same peat from earlier studies are used to evaluate the effect of polarity on the vapor partition in SOM. The extrapolated liquid solubility from the vapor isotherm increases sharply from 3-6 wt % for low-polarity liquids (hexane, CT, and benzene) to 62 wt % for polar methanol and correlates positively with the liquid's component solubility parameters for polar interaction (??P) and hydrogen bonding (??h). The same polarity effect may be expected to influence the relative solubilities of a variety of contaminants in SOM and, therefore, the relative deviations between the SOM-water partition coefficients (Kom) and corresponding octanol-water partition coefficients (Kow) for different classes of compounds. The large solubility disparity in SOM between polar and nonpolar solutes suggests that the accurate prediction of Kom from Kow or Sw (solute water solubility) would be limited to compounds of similar polarity.

  15. Improving oil recovery in the CO2 flooding process by utilizing nonpolar chemical modifiers☆

    Institute of Scientific and Technical Information of China (English)

    Yong Yang; Xiangliang Li; Ping Guo; Yayun Zhuo; Yong Sha

    2016-01-01

    By means of experiments of CO2 miscibility with crude oil, four nonpolar chemicals were evaluated in order to enhance the miscibility of CO2 with crude oil. Through pre-slug injection and joint injection of toluene in CO2, crude oil displacement experiments in the slim-tube were conducted to investigate effects of the toluene-enhanced CO2 flooding under simulated subterranean reservoir conditions. Experimental results showed that toluene can enhance extraction of oil into CO2 and dissolution of CO2 into oil with the increment of 251%and 64%respectively. Addition of toluene can obviously improve the oil recovery in either pre-slug injection or joint injection, and the crude oil recovery increased with the increase of the toluene concentration. The oil recov-ery can increase by 22.5%in pre-slug injection with the high toluene concentration. Pre-slug injection was recom-mended because it can consume less toluene than joint injection. This work could be useful to development and application of the CO2 flooding in the oil recovery as wel as CO2 emission reduction.

  16. Roles of urea and TMAO on the interaction between extended non-polar peptides

    Science.gov (United States)

    Su, Zhaoqian; Dias, Cristiano

    Urea and trimethylamine n-oxide (TMAO) are small molecules known to destabilize and stabilize, respectively, the structure of proteins when added to aqueous solution. To unravel the molecular mechanisms of these cosolvents on protein structure we perform explicit all-atom molecular dynamics simulations of extended poly-alanine and polyleucine dimers. We use an umbrella sampling protocol to compute the potential of mean force (PMF) of dimers at different concentrations of urea and TMAO. We find that the large non-polar side chain of leucine is affected by urea whereas backbone atoms and alanine's side chain are not. Urea is found to occupy positions between leucine's side chains that are not accessible to water. This accounts for extra Lennard-Jones bonds between urea and side chains that favors the unfolded state. These bonds compete with urea-solvent interactions that favor the folded state. The sum of these two energetic terms provide the enthalpic driving force for unfolding. We show here that this enthalpy correlate with the potential of mean force of poly-leucine dimers. Moreover, the framework developed here is general and may be used to provide insights into effects of other small molecules on protein interactions. The effect of the TMAO will be in the presentation. Department of Physics, University Heights, Newark, New Jersey, 07102-1982.

  17. Competitive and cooperative adsorption behaviors of phenol and aniline onto nonpolar macroreticular adsorbents

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-ming; CHEN Jin-long; PAN Bing-cai; ZHANG Quan-xing

    2005-01-01

    The adsorption behaviors of phenol and aniline on nonpolar macroreticular adsorbents( NDA100 and Amberlite XAD4) were investigated in single or binary batch system at 293K and 313K respectively in this study. The results indicated that the adsorption isotherms of phenol and aniline on both adsorbents in both systems fitted well Langmuir equation, which indicated a favourable and exothermic process. At the lower equilibrium concentrations, the individual amount adsorbed of phenol or aniline or macroreticular adsorbents in single-component systems was higher than those in binary-component systems because of the competition between phenol and aniline towards the adsorption sites. It is noteworthy, on the contrast, that at higher concentrations, the total uptake amounts of phenol and aniline in binary-component systems were obviously larger than that in single-component systems, and a large excess was noted on the adsorbent surface at saturation, which is presumably due to the cooperative effect primarily arisen from the hydrogen bonding or weak acidbase interaction between phenol and aniline.

  18. A silicone column for GC analysis of polar and nonpolar chemicals

    Science.gov (United States)

    Shen, T. C.

    1991-10-01

    The investigation of the Saturnian System is being proposed jointly by NASA and the European Space Agency (ESA). The mission is scheduled for a launch in 1996. The mission provides an opportunity for close observation and exploration of Saturn's atmosphere, the complex Saturnian System of satellites and rings, Titan (Saturn's planet-sized moon), and Saturn's magnetosphere. The mission gives special attention to Titan which is blanketed by a thick, opaque atmosphere. An atmospheric probe will be deposited into the Titan Atmosphere for in situ measurement during a slow, three hour descent to the surface. The results from this analysis may provide the information which is important to the research of chemical evolution, and the origin of life. An analytical system was developed as a part of the Titan Aerosol Gas Experiment (TAGEX), a proposed experiment for the Cassini Mission. This system will use two highly sensitive detectors, the Metastable Ionization Detector (MID) and the Ion Mobility Spectrometer (IMS). Unfortunately, when commercial columns are utilized with these highly sensitive detectors, volatile components continuously bleed from the column and interfere with the detector. In addition, light columns must be able to separate polar and nonpolar organic chemicals within 10-15 minutes under isothermal conditions for the Titan Mission. Therefore, a highly crosslinked silicone polymeric packed column was developed which is able to efficiently separate amines, alcohols, and hydrocarbons with retention times less that 15 minutes at 100 C isothermal condition.

  19. Self-consistent theory of nanodomain formation on nonpolar surfaces of ferroelectrics

    Science.gov (United States)

    Morozovska, Anna N.; Ievlev, Anton V.; Obukhovskii, Vyacheslav V.; Fomichov, Yevhen; Varenyk, Oleksandr V.; Shur, Vladimir Ya.; Kalinin, Sergei V.; Eliseev, Eugene A.

    2016-04-01

    We propose a self-consistent theoretical approach capable of describing the features of the anisotropic nanodomain formation induced by a strongly inhomogeneous electric field of a charged scanning probe microscopy tip on nonpolar cuts of ferroelectrics. We obtained that a threshold field, previously regarded as an isotropic parameter, is an anisotropic function that is specified from the polar properties and lattice pinning anisotropy of a given ferroelectric in a self-consistent way. The proposed method for the calculation of the anisotropic threshold field is not material specific, thus the field should be anisotropic in all ferroelectrics with the spontaneous polarization anisotropy along the main crystallographic directions. The most evident examples are uniaxial ferroelectrics, layered ferroelectric perovskites, and low-symmetry incommensurate ferroelectrics. Obtained results quantitatively describe the differences at several times in the nanodomain length experimentally observed on X and Y cuts of LiNb O3 and can give insight into the anisotropic dynamics of nanoscale polarization reversal in strongly inhomogeneous electric fields.

  20. Adsorption of polar, nonpolar, and substituted aromatics to colloidal graphene oxide nanoparticles.

    Science.gov (United States)

    Wang, Fang; Haftka, Joris J-H; Sinnige, Theo L; Hermens, Joop L M; Chen, Wei

    2014-03-01

    We conducted batch adsorption experiments to understand the adsorptive properties of colloidal graphene oxide nanoparticles (GONPs) for a range of environmentally relevant aromatics and substituted aromatics, including model nonpolar compounds (pyrene, phenanthrene, naphthalene, and 1,3-dichlorobenzene) and model polar compounds (1-naphthol, 1-naphthylamine, 2,4-dichlorophenol, and 2,4-dinitrotoluene). GONPs exhibited strong adsorption affinities for all the test compounds, with distribution coefficients on the order of 10(3)-10(6) L/kg. Adsorption to GONPs is much more linear than to carbon nanotubes (CNTs) and C60, likely because GO nanoflakes are essentially individually dispersed (rendering adsorption sites of similar adsorption energy) whereas CNT/C60 are prone to bundling/aggregation. For a given compound GONPs and CNTs often exhibit different adsorption affinities, which is attributable to the differences in both the morphology and surface chemistry between the two nanomaterials. Particularly, the high surface O-content of GONPs enables strong H-bonding and Lewis acid-base interactions with hydroxyl- and amino-substituted aromatics.

  1. Molecular Dynamics Simulation of Behaviours of Non-Polar Droplets Merging and Interactions with Hydrophobic Surfaces

    Institute of Scientific and Technical Information of China (English)

    Y.Y.Yan; C.Y.Ji

    2008-01-01

    This paper presents a molecular dynamics simulation of the behaviours of non-polar droplets merging and also the fluid molecules interacting with a hydrophobic surface. Such behaviours and transport phenomena are popular in general micro-channel flow boiling and two-phase flow. The droplets are assumed to be composed of Lennards-Jones type molecules. Periodic boundary conditions are applied in three coordinate directions ofa 3-D system, where there exist two liquid droplets and their vapour. The two droplets merge when they come within the prescribed small distance. The merging of two droplets apart from each other at different initial distances is tested and the possible larger (or critical) non-dimensional distance, in which droplets merging can occur, is discussed. The evolution of the merging process is simulated numerically by employing the Molecular Dynamics (MD) method. For interactions with hydrophobic solid wail, a system with fluid confined between two walls is used to study the wetting phenomena of fluid and solid wail. The results are compared with those of hydrophilic wall to show the unique characteristics of hydrophobic interactions by microscopic methods.

  2. Composition of the non-polar extracts and antimicrobial activity of Chorisia insignis HBK. leaves

    Directory of Open Access Journals (Sweden)

    Salma Ahmed Mahmoud El Sawi

    2014-12-01

    Full Text Available Objective: To investigate the chemical constituents of the petroleum ether extract and the ether fraction of the 70% ethanol extract of Chorisia insignis HBK. leaves, as well as screen its antimicrobial activity. Methods: Different chromatographic methods were applied to investigate the non-polar extracts and the diffusion assay method was applied to study the antimicrobial activity. Results: A total of 50 compounds from the unsaponifiable matter and 20 fatty acid methyl esters were identified from the petroleum ether extract by GC/MS analysis. n-Hentriacontane, n-tritriacontane, stigmastanol, 3-methoxy-5, 6-dihydrostigmasterol, 7,8-dihydroergosterol, 4-methylcholesterol, cholestanol, multiflorenol, cholest-5-en-3-one, cholest-6-one, 5,6- dihydroergosterol, stigmasterol, dihydroalbigenin and 11-methyl-Δ5,7,9,15,17,23-triacont-hex-ene were isolated from the petroleum ether extract. Methyl heptacosanoate and quinic acid ester of rhamnose were isolated from the ether fraction of the 70% ethanol extract. Antimicrobial activity of the total alcohol extract and the successive fractions showed that the ether and the ethyl acetate fractions have potent antibacterial activity against Bacillus subtilis and Bacillus cereus. Conclusions: The ether and the ethyl acetate fractions could be used in pharmaceutical formulations as antibacterial agents against Bacillus subtilis and Bacillus cereus, and further clinical trials should be performed in order to support the above investigations.

  3. Piezoelectricity and rotostriction through polar and non-polar coupled instabilities in bismuth-based piezoceramics

    Science.gov (United States)

    Acosta, Matias; Schmitt, Ljubomira A.; Cazorla, Claudio; Studer, Andrew; Zintler, Alexander; Glaum, Julia; Kleebe, Hans-Joachim; Donner, Wolfgang; Hoffman, Mark; Rödel, Jürgen; Hinterstein, Manuel

    2016-07-01

    Coupling of order parameters provides a means to tune functionality in advanced materials including multiferroics, superconductors, and ionic conductors. We demonstrate that the response of a frustrated ferroelectric state leads to coupling between order parameters under electric field depending on grain orientation. The strain of grains oriented along a specific crystallographic direction, , is caused by converse piezoelectricity originating from a ferrodistortive tetragonal phase. For hhh> oriented grains, the strain results from converse piezoelectricity and rotostriction, as indicated by an antiferrodistortive instability that promotes octahedral tilting in a rhombohedral phase. Both strain mechanisms combined lead to a colossal local strain of (2.4 ± 0.1) % and indicate coupling between oxygen octahedral tilting and polarization, here termed “rotopolarization”. These findings were confirmed with electromechanical experiments, in situ neutron diffraction, and in situ transmission electron microscopy in 0.75Bi1/2Na1/2TiO3-0.25SrTiO3. This work demonstrates that polar and non-polar instabilities can cooperate to provide colossal functional responses.

  4. Analysis of current transport properties in nonpolar a-plane ZnO-based Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hogyoung [Seoul National University of Science and Technology, Seoul (Korea, Republic of); Kim, Haeri; Kim, Dongwook [Ewha Womans University, Seoul (Korea, Republic of)

    2014-09-15

    Using current-voltage (I - V) measurements, we investigated the temperature-dependent transport properties in Ag/nonpolar a-plane ZnO Schottky diodes. The bias-dependent ideality factors were altered by the different temperatures and showed a hump at lower temperatures. The series resistance of the diode depended on the temperatures, which was related to the number of free carriers contributing to the series resistance. For high forward bias, the slope m obtained from the lnI - lnV curves decreased with increasing temperature, assuring the space-charge-limited-current (SCLC) model controlled by an exponential distribution of traps. The reverse-biased current transport was associated with the Schottky effect, with a thermally-assisted tunneling for lower voltages and the Poole-Frenkel effect for higher voltages. The density of localized states (N{sub t}) was obtained by applying the theory of SCLC transport, which yielded a N{sub t} value of 8.32 x 10{sup 11} eV{sup -1}cm{sup -3}.

  5. Media Flow

    DEFF Research Database (Denmark)

    Kabel, Lars

    2016-01-01

    News and other kinds of journalistic stories, 16-17 hours a day, all year round, on all platforms, also the moderated social media. The key research thesis behind this article is that the continuous and speedy stream of news stories and media content now is becoming the centre of the production...

  6. Mixed Media

    Science.gov (United States)

    Peterson, Erin

    2010-01-01

    While institutions do not often have a hook as compelling as an eagerly awaited movie, great content is critical for media relations success--and coupling it with the right distribution channel can ensure the story finds the right audience. Even better, retooling it for several media platforms can extend the life and reach of a story. The changes…

  7. Media places

    DEFF Research Database (Denmark)

    Linde, Per; Messeter, Jörn

    for the Media places project, give some brief insights into the themes of setting up temporary digital streams of media and mobile games. Considering the work-in-progress character of the research and the smaller format of text, no real in-depth analysis will be carried out. The goal is rather to position...

  8. Mixed Media

    Science.gov (United States)

    Peterson, Erin

    2010-01-01

    While institutions do not often have a hook as compelling as an eagerly awaited movie, great content is critical for media relations success--and coupling it with the right distribution channel can ensure the story finds the right audience. Even better, retooling it for several media platforms can extend the life and reach of a story. The changes…

  9. Media darling

    CERN Multimedia

    Chalmers, Matthew

    2008-01-01

    He is the media-friendly face of particle physics, appearing on countless TV and radio shows in the run-up to the opening of CERN's Large Hadron Collider. Matthew Chalmers discovers how Brian Cox finds the time to be both a physicist and a media personality. (2 pages)

  10. Transport of Polycyclic Aromatic Hydrocarbons in Unsaturated Porous Media

    Science.gov (United States)

    Chahal, Maninder; Flury, Markus

    2016-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are complex organic molecules containing 2 or more fused benzene rings. Being hydrophobic and non-polar, PAHs tend to partition to the organic matter in the soil from bulk aqueous phase. Though transport of these contaminants has been well studied in saturated environment, interactive mechanisms of these fluorescent compounds in unsaturated (identified by presence of air-water interface) porous media is still not well understood. We studied is the transport of fluoranthene in unsaturated porous media as facilitated by moving air-water interfaces. Confocal microscopy was used to visualize the interactions of fluoranthene particles in a glass channel packed with quartz glass beads. The packed glass channel was used to mimic a porous media and effects of an advancing and receding capillary fringe on the detachment of fluoranthene.

  11. Electroluminescence from nonpolar n-ZnO/p-AlGaN heterojunction light-emitting diode on r-sapphire

    Science.gov (United States)

    Chen, Jingwen; Zhang, Jun; Dai, Jiangnan; Wu, Feng; Wang, Shuai; Chen, Cheng; Long, Hanling; Liang, Renli; Zhao, Chong; Chen, Changqing; Tang, Zhiwu; Cheng, Hailing; He, Yunbin; Li, Mingkai

    2017-03-01

    Nonpolar a-plane n-ZnO/p-AlGaN heterojunction light-emitting diodes (LEDs) have been prepared on r-sapphire substrate using metal organic chemical vapor deposition and a pulsed laser deposition method. The dominant electroluminescence emission at 390 nm from the interband transition in n-ZnO layer under a forward bias was observed. Interestingly, electroluminescence with emission at 385 nm based on an avalanche mechanism was also achieved under reverse bias. The mechanisms of both the electroluminescence and I–V characteristics are discussed in detail by considering the avalanche effect. It is demonstrated that the crystalline quality of n-ZnO, not the p-AlGaN, is what affects the performance of the nonpolar ZnO based avalanche LED.

  12. Homoepitaxial nonpolar (10-10) ZnO/ZnMgO monolithic microcavities: Towards reduced photonic disorder

    Energy Technology Data Exchange (ETDEWEB)

    Zuniga-Perez, J., E-mail: jzp@crhea.cnrs.fr; Kappei, L.; Deparis, C.; Chenot, S.; Leroux, M. [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France); Reveret, F.; Jamadi, O.; Leymarie, J. [Clermont Université, Institut Pascal (IP), BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6602, IP, F-63171 Aubière (France); Grundmann, M. [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France); Institut für Experimentelle Physik II, Fakultät für Physik und Geowissenschaften, Universität Leipzig, Linnestr. 5, 04103 Leipzig (Germany); Prado, E. de [CRHEA-CNRS, Rue Bernard Gregory, 06560 Valbonne (France); Departamento de Física Aplicada y Electromagnetismo, Universitat de Valencia, c/Dr Moliner 50, Burjassot, Valencia 46100 (Spain)

    2016-06-20

    Nonpolar ZnO/ZnMgO-based optical microcavities have been grown on (10-10) m-plane ZnO substrates by plasma-assisted molecular beam epitaxy. Reflectivity measurements indicate an exponential increase of the cavity quality factor with the number of layers in the distributed Bragg reflectors. Most importantly, microreflectivity spectra recorded with a spot size in the order of 2 μm show a negligible photonic disorder (well below 1 meV), leading to local quality factors equivalent to those obtained by macroreflectivity. The anisotropic character of the nonpolar heterostructures manifests itself both in the surface features, elongated parallel to the in-plane c direction, and in the optical spectra, with two cavity modes being observed at different energies for orthogonal polarizations.

  13. An analytical method of predicting Lee-Kesler-Ploecker binary interaction coefficients: Part 1, For non-polar hydrocarbon mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Sand, J.R.

    1994-12-31

    An analytical method is proposed for finding numerical values of binary interaction coefficients for non-polar hydrocarbon mixtures when the Lee-Kesler (LK) equation of state is applied. The method is based on solving simultaneous equations, which are Ploecker`s mixing rules for pseudocritical parameters of a mixture, and the Lee-Kesler equation for the saturation line. For a hydrocarbon mixture, the method allows prediction of {kappa}{sub ij} interaction coefficients (ICs) which are close to values obtained by processing experimental p-v-t data on the saturation line and subsequent averaging. For mixtures of hydrocarbon molecules containing from 2 to 9 carbon atoms, the divergence between calculated and experimentally based ICs is no more than {plus_minus}0.4%. The possibility of extending application of this method to other non-polar substances is discussed.

  14. The atomic structure of polar and non-polar InGaN quantum wells and the green gap problem.

    Science.gov (United States)

    Humphreys, C J; Griffiths, J T; Tang, F; Oehler, F; Findlay, S D; Zheng, C; Etheridge, J; Martin, T L; Bagot, P A J; Moody, M P; Sutherland, D; Dawson, P; Schulz, S; Zhang, S; Fu, W Y; Zhu, T; Kappers, M J; Oliver, R A

    2017-02-03

    We have used high resolution transmission electron microscopy (HRTEM), aberration-corrected quantitative scanning transmission electron microscopy (Q-STEM), atom probe tomography (APT) and X-ray diffraction (XRD) to study the atomic structure of (0001) polar and (11-20) non-polar InGaN quantum wells (QWs). This paper provides an overview of the results. Polar (0001) InGaN in QWs is a random alloy, with In replacing Ga randomly. The InGaN QWs have atomic height interface steps, resulting in QW width fluctuations. The electrons are localised at the top QW interface by the built-in electric field and the well-width fluctuations, with a localisation energy of typically 20meV. The holes are localised near the bottom QW interface, by indium fluctuations in the random alloy, with a localisation energy of typically 60meV. On the other hand, the non-polar (11-20) InGaN QWs contain nanometre-scale indium-rich clusters which we suggest localise the carriers and produce longer wavelength (lower energy) emission than from random alloy non-polar InGaN QWs of the same average composition. The reason for the indium-rich clusters in non-polar (11-20) InGaN QWs is not yet clear, but may be connected to the lower QW growth temperature for the (11-20) InGaN QWs compared to the (0001) polar InGaN QWs.

  15. Tailoring of polar and nonpolar ZnO planes on MgO (001) substrates through molecular beam epitaxy.

    Science.gov (United States)

    Zhou, Hua; Wang, Hui-Qiong; Liao, Xia-Xia; Zhang, Yufeng; Zheng, Jin-Cheng; Wang, Jia-Ou; Muhemmed, Emin; Qian, Hai-Jie; Ibrahim, Kurash; Chen, Xiaohang; Zhan, Huahan; Kang, Junyong

    2012-03-09

    Polar and nonpolar ZnO thin films were deposited on MgO (001) substrates under different deposition parameters using oxygen plasma-assisted molecular beam epitaxy (MBE). The orientations of ZnO thin films were investigated by in situ reflection high-energy electron diffraction and ex situ X-ray diffraction (XRD). The film roughness measured by atomic force microscopy evolved as a function of substrate temperature and was correlated with the grain sizes determined by XRD. Synchrotron-based X-ray absorption spectroscopy (XAS) was performed to study the conduction band structures of the ZnO films. The fine structures of the XAS spectra, which were consistent with the results of density functional theory calculation, indicated that the polar and nonpolar ZnO films had different electronic structures. Our work suggests that it is possible to vary ZnO film structures from polar to nonpolar using the MBE growth technique and hence tailoring the electronic structures of the ZnO films.PACS: 81; 81.05.Dz; 81.15.Hi.

  16. The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

    Science.gov (United States)

    Dawson, P.; Schulz, S.; Oliver, R. A.; Kappers, M. J.; Humphreys, C. J.

    2016-05-01

    In this paper, we compare and contrast the experimental data and the theoretical predictions of the low temperature optical properties of polar and nonpolar InGaN/GaN quantum well structures. In both types of structure, the optical properties at low temperatures are governed by the effects of carrier localisation. In polar structures, the effect of the in-built electric field leads to electrons being mainly localised at well width fluctuations, whereas holes are localised at regions within the quantum wells, where the random In distribution leads to local minima in potential energy. This leads to a system of independently localised electrons and holes. In nonpolar quantum wells, the nature of the hole localisation is essentially the same as the polar case but the electrons are now coulombically bound to the holes forming localised excitons. These localisation mechanisms are compatible with the large photoluminescence linewidths of the polar and nonpolar quantum wells as well as the different time scales and form of the radiative recombination decay curves.

  17. Interactions of methanol, ethanol, and 1-propanol with polar and nonpolar species in water at cryogenic temperatures.

    Science.gov (United States)

    Souda, Ryutaro

    2017-01-18

    Methanol is known as a strong inhibitor of hydrate formation, but clathrate hydrates of ethanol and 1-propanol can be formed in the presence of help gases. To elucidate the hydrophilic and hydrophobic effects of alcohols, their interactions with simple solute species are investigated in glassy, liquid, and crystalline water using temperature-programmed desorption and time-of-flight secondary ion mass spectrometry. Nonpolar solute species embedded underneath amorphous solid water films are released during crystallization, but they tend to withstand water crystallization under the coexistence of methanol additives. The CO2 additives are released after crystallization along with methanol desorption. These results suggest strongly that nonpolar species that are hydrated (i.e., caged) associatively with methanol can withstand water crystallization. In contrast, ethanol and 1-propanol additives weakly affect the dehydration of nonpolar species during water crystallization, suggesting that the former tend to be caged separately from the latter. The hydrophilic vs. hydrophobic behavior of alcohols, which differs according to the aliphatic group length, also manifests itself in the different abilities of surface segregation of alcohols and their effects on the water crystallization kinetics.

  18. Media violence.

    Science.gov (United States)

    Cantor, J

    2000-08-01

    Research on the effects of media violence is not well understood by the general public. Despite this fact, there is an overwhelming consensus in the scientific literature about the unhealthy effects of media violence. Meta-analyses show that media-violence viewing consistently is associated with higher levels of antisocial behavior, ranging from the trivial (imitative violence directed against toys) to the serious (criminal violence), with many consequential outcomes in between (acceptance of violence as a solution to problems, increased feelings of hostility, and the apparent delivery of painful stimulation to another person). Desensitization is another well-documented effect of viewing violence, which is observable in reduced arousal and emotional disturbance while witnessing violence, the reduced tendency to intervene in a fight, and less sympathy for the victims of violence. Although there is evidence that youth who are already violent are more likely to seek out violent entertainment, there is strong evidence that the relationship between violence viewing and antisocial behavior is bidirectional. There is growing evidence that media violence also engenders intense fear in children which often lasts days, months, and even years. The media's potential role in solutions to these problems is only beginning to be explored, in investigations examining the uses and effects of movie ratings, television ratings, and the V-chip, and the effects of media literacy programs and public education efforts. Future research should explore important individual differences in responses to media violence and effective ways to intervene in the negative effects.

  19. Comparative Study of the Characteristics of the Basal Plane Stacking Faults of Nonpolar a-Plane and Semipolar (11(2)2) GaN

    Institute of Scientific and Technical Information of China (English)

    XU Sheng-Rui; HAO Yue; LIN Zhi-Yu; XUE Xiao-Yong; LIU Zi-Yang; MA Jun-Cai; JIANG Teng; MAO Wei; WANG Dang-Hui; ZHANG Jin-Cheng

    2012-01-01

    Nonpolar (11-20) and semipolar (11222) GaN are grown on r-plane and m-plane sapphire by MOCVD to investigate the characteristics of basal plane stacking faults (BSFs). Transmission electron microscopy reveals that the density of BSFs for the semipolar (11-22) and nonpolar a-plane GaN template is 3×105cm-1 and 8×10 cm'1, respectively. The semipolar (11-22) GaN shows an arrowhead-like structure, and the nonpolar a-plane GaN has a much smoother morphology with a streak along the c-axis. Both nonpolar (11-20) and semipolar (11-22) GaN have very strong BSF luminescence due to the optically active character of the BSFs.%Nonpolar (11(2)0) and semipolar (11(2)2) GaN are grown on r-plane and m-plane sapphire by MOCVD to investigate the characteristics of basal plane stacking faults (BSFs).Transmission electron microscopy reveals that the density of BSFs for the semipolar (11(2)2) and nonpolar a-plane GaN template is 3x105 cm-1 and 8×105 cm-1,respectively.The semipolar (11(2)2) GaN shows an arrowhead-like structure,and the nonpolar a-plane GaN has a much smoother morphology with a streak along the c-axis.Both nonpolar (11(2)0) and semipolar (11(2)2) GaN have very strong BSF luminescence due to the optically active character of the BSFs.

  20. Recent Advances in Nonpolar and Semipolar InGaN Light-Emitting Diodes (LEDs).

    Science.gov (United States)

    Jang, Jongjin; Woo, Seohwi; Min, Daehong; Nam, Okhyun

    2015-03-01

    The III-nitrides have attracted much attention because of their applicability in optoelectronic devices, whose emission wavelengths range from green to ultraviolet light due to their wide band gap. However, conventional c-plane GaN-based devices are influenced significantly by spontaneous and piezoelectric polarization effects, which could pose a limitation for increased luminous efficiency as a result of the quantum confined stark effect. Since the early 2000s, many groups have tried to solve these problems by examining the growth of GaN on non- or semipolar surface planes. High power non- and semipolar LEDs can be realized by the growth of a thick active layer. In addition, it is expected that it is possible to grow nonpolar InGaN LEDs with high quality p-GaN layers due to lower hole activation energy, and also long-wavelength semipolar InGaN LEDs because of the capacity for high indium incorporation in the quantum wells (QWs). However, non- and semipolar structures grown on sapphire substrate usually contain a high density of basal stacking faults and threading dislocations. For this reason, the growth of non- and semipolar GaN-based LEDs on a sapphire substrate has been attempted through the introduction of defect reduction techniques such as epitaxial lateral overgrowth, patterned sapphire substrate and re-growth techniques on a porous GaN layer, etc. Also, some researchers have grown high quality non- and semipolar GaN-based LEDs using non- and semipolar freestanding GaN substrates. In this review paper, we introduce and discuss recent progress in the development of non- and semipolar GaN-based LEDs and freestanding GaN substrates.

  1. Schottky contact formation on polar and non-polar AlN

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Pramod; Bryan, Isaac; Bryan, Zachary; Tweedie, James; Kirste, Ronny; Collazo, Ramon; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States)

    2014-11-21

    The interfaces of m- and c-plane AlN with metals of different work functions and electro-negativities were characterized and the Schottky barrier heights were measured. The Schottky barrier height was determined by measuring the valence band maximum (VBM) with respect to the Fermi level at the surface (interface) before (after) metallization. VBM determination included accurate modeling and curve fitting of density of states at the valence band edge with the XPS data. The experimental behavior of the barrier heights could not be explained by the Schottky-Mott model and was modeled using InterFace-Induced Gap States (IFIGS). A slope parameter (S{sub X}) was used to incorporate the density of surface states and is a measure of Fermi level pinning. The experimental barriers followed theoretical predictions with a barrier height at the surface Fermi level (Charge neutrality level (CNL)) of ∼2.1 eV (∼2.7 eV) on m-plane (c-plane) and S{sub X} ∼ 0.36 eV/Miedema unit. Slope parameter much lower than 0.86 implied a surface/interface states dominated behavior with significant Fermi level pinning and the measured barrier heights were close to the CNL. Titanium and zirconium provided the lowest barriers (1.6 eV) with gold providing the highest (2.3 eV) among the metals analyzed on m-plane. It was consistently found that barrier heights decreased from metal polar to non-polar surfaces, in general, due to an increasing CNL. The data indicated that charged IFIGS compensate spontaneous polarization charge. These barrier height and slope parameter measurements provided essential information for designing Schottky diodes and other contact-based devices on AlN.

  2. Foaming properties of monoglycerol fatty acid esters in nonpolar oil systems.

    Science.gov (United States)

    Shrestha, Lok Kumar; Aramaki, Kenji; Kato, Hiroyuki; Takase, Yoshihiko; Kunieda, Hironobu

    2006-09-26

    Foaming properties of monoglycerol fatty acid esters that have different alkyl chain lengths were studied in different nonpolar oils, namely liquid paraffin (LP 70), squalane, and squalene. The effect of the hydrocarbon chain length of the surfactant, the concentration, the nature of the oil, and the temperature on the nonaqueous foam stability was mainly studied. Five weight percent of glycerol alpha-monododecanoate (monolaurin) formed highly stable foams in squalane at 25 degrees C, and the foams were stable for more than 14 h. Foam stability of the monolaurin/LP 70 and the monolaurin/squalene systems are almost similar, and the foams were stable for more than 12 h. Foam stability was decreased as the hydrocarbon chain length of the monoglyceride decreased. In the glycerol alpha-monodecanoate (monocaprin)-oil systems, the foams were stable only for 3-4 h, depending on the nature of the oil. However, the foams formed in the glycerol alpha-monooctanoate (monocaprylin)-oil systems coarsened very quickly, leading to the progressive destruction of foam films, and all of the foams collapsed within a few minutes. Foam stability decreased when the oil was changed from squalane to squalene, in both monocaprin and monolaurin systems. It was observed that, in the dilute regions, these monoglycerides form fine solid dispersions in the aforementioned oils at 25 degrees C. At higher temperatures, the solid melts to isotropic single-liquid or two-liquid phases and the foams formed collapsed within 5 min. Judging from the wide-angle X-ray scattering (WAXS) and the foaming test, it is concluded that the stable foams are mainly caused by the dispersion of the surfactant solids (beta-crystal) and foam stability is largely influenced by the shape and size of the dispersed solid particles.

  3. Nitrobenzene anti-parallel dimer formation in non-polar solvents

    Directory of Open Access Journals (Sweden)

    Toshiyuki Shikata

    2014-06-01

    Full Text Available We investigated the dielectric and depolarized Rayleigh scattering behaviors of nitrobenzene (NO2-Bz, which is a benzene mono-substituted with a planar molecular frame bearing the large electric dipole moment 4.0 D, in non-polar solvents solutions, such as tetrachloromethane and benzene, at up to 3 THz for the dielectric measurements and 8 THz for the scattering experiments at 20 °C. The dielectric relaxation strength of the system was substantially smaller than the proportionality to the concentration in a concentrated regime and showed a Kirkwood correlation factor markedly lower than unity; gK ∼ 0.65. This observation revealed that NO2-Bz has a tendency to form dimers, (NO2-Bz2, in anti-parallel configurations for the dipole moment with increasing concentration of the two solvents. Both the dielectric and scattering data exhibited fast and slow Debye-type relaxation modes with the characteristic time constants ∼7 and ∼50 ps in a concentrated regime (∼15 and ∼30 ps in a dilute regime, respectively. The fast mode was simply attributed to the rotational motion of the (monomeric NO2-Bz. However, the magnitude of the slow mode was proportional to the square of the concentration in the dilute regime; thus, the mode was assigned to the anti-parallel dimer, (NO2-Bz2, dissociation process, and the slow relaxation time was attributed to the anti-parallel dimer lifetime. The concentration dependencies of both the dielectric and scattering data show that the NO2-Bz molecular processes are controlled through a chemical equilibrium between monomers and anti-parallel dimers, 2NO2-Bz ↔ (NO2-Bz2, due to a strong dipole-dipole interaction between nitro groups.

  4. From Augmentation Media to Meme Media.

    Science.gov (United States)

    Tanaka, Yuzuru

    Computers as meta media are now evolving from augmentation media vehicles to meme media vehicles. While an augmentation media system provides a seamlessly integrated environment of various tools and documents, meme media system provides further functions to edit and distribute tools and documents. Documents and tools on meme media can easily…

  5. Community Media: Muting the Democratic Media Discourse?

    NARCIS (Netherlands)

    Carpentier, N.; Lie, R.; Servaes, J.

    2003-01-01

    Focuses on the concept of community media. Components that construct the identity of community media; Multi-theoretical approaches for analysis of community media; Definition of community media based on the concept of alternative media; Link between community media and civil society; Problems faced

  6. OTITIS MEDIA

    African Journals Online (AJOL)

    to managers of Essential Medicines programmes. ... media (AOM) in children as an example of such a condition, in order Lo explore these challenges more closely. ... pain, fever or deafness) and the ... at 15 and 30 minutes after each morning.

  7. Media violence.

    Science.gov (United States)

    Willis, E; Strasburger, V C

    1998-04-01

    American media are the most violent in the world, and American society is now paying a high price in terms of real life violence. Research has confirmed that mass media violence contributes to aggressive behavior, fear, and desensitization of violence. Television, movies, music videos, computer/video games are pervasive media and represent important influences on children and adolescents. Portraying rewards and punishments and showing the consequences of violence are probably the two most essential contextual factors for viewers as they interpret the meaning of what they are viewing on television. Public health efforts have emphasized public education, media literacy campaign for children and parents, and an increased use of technology to prevent access to certain harmful medial materials.

  8. Media democracy

    NARCIS (Netherlands)

    Pels, D.

    2008-01-01

    The present article compendiously presents the interlinked and abruptly developing processes of media democracy and political matters’ personalization. The writer expressly opts for these processes which can radically rejuvenate communication and trust among citizens and politicians and therefore

  9. Media Bias

    OpenAIRE

    Sendhil Mullainathan; Andrei Shleifer

    2002-01-01

    There are two different types of media bias. One bias, which we refer to as ideology, reflects a news outlet's desire to affect reader opinions in a particular direction. The second bias, which we refer to as spin, reflects the outlet's attempt to simply create a memorable story. We examine competition among media outlets in the presence of these biases. Whereas competition can eliminate the effect of ideological bias, it actually exaggerates the incentive to spin stories.

  10. Social Media

    OpenAIRE

    2013-01-01

    Anlässlich der 10. Wissenschaftlichen Tagung „Soziale Medien“ am 27. und 28. Juni 2013 im Statistischen Bundesamt in Wiesbaden und in Fortsetzung des 2010 erschienenen Recherche Spezial Web 2.0 – Alle machen mit! werden in dieser Ausgabe in sechs Kapiteln Nachweise zu Veröffentlichungen und Forschungsprojekte der letzten drei Jahre zusammengestellt, die sich mit der Rolle von Social Media in verschiedenen Nutzungskontexten befassen. Social-Media-Dienste sind mittlerweile fester Bestandtei...

  11. Social media management and media environment

    OpenAIRE

    Šiđanin Iva

    2012-01-01

    The paper deals with the system of services that social media management can offer to a variety of users. As social media systems are emerging, social media management can strengthen teams in social media and help to manage numerous social channels and distribution of social information from one place. Social media management is a system of procedures that are used to manage the flow of information in the environment of social media. This involves connecting with social media like Facebook, T...

  12. Kinetic and fluid descriptions of charged particle swarms in gases and nonpolar fluids: Theory and applications

    Science.gov (United States)

    Dujko, Sasa

    2016-09-01

    In this work we review the progress achieved over the last few decades in the fundamental kinetic theory of charged particle swarms with the focus on numerical techniques for the solution of Boltzmann's equation for electrons, as well as on the development of fluid models. We present a time-dependent multi term solution of Boltzmann's equation valid for electrons and positrons in varying configurations of electric and magnetic fields. The capacity of a theory and associated computer code will be illustrated by considering the heating mechanisms for electrons in radio-frequency electric and magnetic fields in a collision-dominated regime under conditions when electron transport is greatly affected by non-conservative collisions. The kinetic theory for solving the Boltzmann equation will be followed by a fluid equation description of charged particle swarms in both the hydrodynamic and non-hydrodynamic regimes, highlighting (i) the utility of momentum transfer theory for evaluating collisional terms in the balance equations and (ii) closure assumptions and approximations. The applications of this theory are split into three sections. First, we will present our 1.5D model of Resistive Plate Chambers (RPCs) which are used for timing and triggering purposes in many high energy physics experiments. The model is employed to study the avalanche to streamer transition in RPCs under the influence of space charge effects and photoionization. Second, we will discuss our high-order fluid model for streamer discharges. Particular emphases will be placed on the correct implementation of transport data in streamer models as well as on the evaluation of the mean-energy-dependent collision rates for electrons required as an input in the high-order fluid model. In the last segment of this work, we will present our model to study the avalanche to streamer transition in non-polar fluids. Using a Monte Carlo simulation technique we have calculated transport coefficients for electrons in

  13. White light-emitting diodes based on nonpolar and semipolar gallium nitride orientations

    Science.gov (United States)

    Demille, Natalie Fellows

    Gallium nitride has become one of the key components when fabricating white light-emitting diodes. Its use as the blue source in conjunction with a wavelength converter such as the yellow emitting phosphor YAG:Ce 3+ is a technology that is commercially available and usable for solid state lighting applications. Currently available white phosphor-based LEDs (pcLEDs) use the basal plane of wurtzite GaN as their source. Although research over the past couple decades has developed this technology into devices with good photometric performance and high reliability, the introduction of nonbasal plane wurtzite GaN orientations have benefits over basal plane GaN that can be incorporated into the white LED. The focus of this research deals with exploring white illumination on nonpolar and semipolar planes of GaN. Light extraction techniques will be described that allowed for high output powers and efficiencies on the c-plane as well as the (1100), (10 11), and (1122) planes of GaN. With higher performing devices, white pcLEDs were fabricated on c-plane, m-plane, and the (1011) semipolar plane. The novelty in the present research is producing white LEDs with nonbasal plane diodes which exhibit optical polarization anisotropy. This feature, absent on the basal plane, allows for tuning photometric quantities both electrically and optically. This is demonstrated on pcLEDs as well as dichromatic LEDs comprised solely of InGaN diodes. As a consequence of these measurements, an apparent optical polarization was seen to be occurring in the luminescence of the YAG:Ce3+ when the system absorbed linearly polarized light. Polarized emission in YAG:Ce3+ was explored by obtaining single crystals of YAG:Ce3+ with different planar orientations. The experiments led to the conclusion that crystal orientation plays no part in the optical polarization. It is suggested that the cause is a result of electric dipole transitions given by various selection rules between the Ce 3+ ion's 4f and 5d

  14. Media Training

    CERN Document Server

    CERN. Geneva

    2009-01-01

    With the LHC starting up soon, the world's media are again turning their attention to CERN. We're all likely to be called upon to explain what is happening at CERN to media, friends and neighbours. The seminar will be given by BBC television news journalists Liz Pike and Nadia Marchant, and will deal with the kind of questions we're likely to be confronted with through the restart period. The training is open for everybody. Make sure you arrive early enough to get a seat - there are only 200 seats in the Globe. The session will also be webcast: http://webcast.cern.ch/

  15. The flotation of Roşia Poieni copper ore in column machine, with non-polar oils addition

    Directory of Open Access Journals (Sweden)

    Ciocani V.

    2005-11-01

    Full Text Available The most important natural resource of copper in Romania is the ore deposit of Roşia Poieni. At present, the utilization of Roşia Poieni poorphyry copper ore is possible by extraction in quarry of the mass ore and mineral processing into a technological flux with modest results for the value of metal recovery in concentrate 70-72 % and an average contents of 16,5 % Cu. Our researches were directed to studies regarding test and utilisation of special procedure of flotation – addition of the non-polar oil – applied to advanced grinding ore with column type machines.

  16. Free ion yields for nonpolar liquids exposed to 1.6-3.5 keV X-rays

    CERN Document Server

    Holroyd, R A

    1998-01-01

    The yields of free ions formed following absorption of 1.6-3.5 keV X-rays were determined for several nonpolar liquids using a conductivity technique. The yields are much less for X-rays than for gamma rays; this effect is largest for branched hydrocarbons. A minimum in yield is observed around 2 keV. The dependence of G sub f sub i sup o on X-ray energy is in good agreement with computer simulations. For tetramethylsilane a sharp dip in ion yield is observed at the Si ls -> sigma sup * resonance, indicating that the free electron yield is even less at this energy.

  17. Streaming Media

    Science.gov (United States)

    Pulley, John

    2009-01-01

    At a time when the evolutionary pace of new media resembles the real-time mutation of certain microorganisms, the age-old question of how best to connect with constituents can seem impossibly complex--even for an elite institution plugged into the motherboard of Silicon Valley. Identifying the most effective vehicle for reaching a particular…

  18. Otitis media

    NARCIS (Netherlands)

    Rovers, MM; Schilder, AGM; Zielhuis, GA; Rosenfeld, RM

    2004-01-01

    Otitis media (OM) continues to be one of the most common childhood infections and is a major cause of morbidity in children. The pathogenesis of OM is multifactorial, involving the adaptive and native immune system, Eustachian-tube dysfunction, viral and bacterial load, and genetic and environmental

  19. Streaming Media

    Science.gov (United States)

    Pulley, John

    2009-01-01

    At a time when the evolutionary pace of new media resembles the real-time mutation of certain microorganisms, the age-old question of how best to connect with constituents can seem impossibly complex--even for an elite institution plugged into the motherboard of Silicon Valley. Identifying the most effective vehicle for reaching a particular…

  20. [Chronic otitis mediaChronic Otitis Media].

    Science.gov (United States)

    Kohles, N; Schulz, T; Eßer, D

    2015-11-01

    There are 2 different kinds of chronic otitis media: Otitis media chronica mesotympanalis and otitis media chronica epitympanalis (cholesteatoma). The incidence of chronic otitis media as reported in literature differs in a wide range. The incidence rates vary between 0.45 and 46%. Both, otitis media chronica mesotympanalis and cholesteatoma, lead to eardrum perforation due to lengthy and recurring inflammations. Furthermore, chronic otitis media is characterized by frequently recurring otorrhea and conductive hearing loss. Georg Thieme Verlag KG Stuttgart · New York.

  1. Vacuum-UV spectroscopy of interstellar ice analogs. II. Absorption cross-sections of nonpolar ice molecules

    CERN Document Server

    Cruz-Diaz, G A; Chen, Y -J; Yih, T -S

    2014-01-01

    Dust grains in cold circumstellar regions and dark-cloud interiors at 10-20 K are covered by ice mantles. A nonthermal desorption mechanism is invoked to explain the presence of gas-phase molecules in these environments, such as the photodesorption induced by irradiation of ice due to secondary ultraviolet photons. To quantify the effects of ice photoprocessing, an estimate of the photon absorption in ice mantles is required. In a recent work, we reported the vacuum-ultraviolet (VUV) absorption cross sections of nonpolar molecules in the solid phase. The aim was to estimate the VUV-absorption cross sections of nonpolar molecular ice components, including CH4, CO2, N2, and O2. The column densities of the ice samples deposited at 8 K were measured in situ by infrared spectroscopy in transmittance. VUV spectra of the ice samples were collected in the 120-160 nm (10.33-7.74 eV) range using a commercial microwave-discharged hydrogen flow lamp. We found that, as expected, solid N2 has the lowest VUV-absorption cros...

  2. Radiative recombination mechanisms in polar and non-polar InGaN/GaN quantum well LED structures

    Science.gov (United States)

    Badcock, T. J.; Ali, M.; Zhu, T.; Pristovsek, M.; Oliver, R. A.; Shields, A. J.

    2016-10-01

    We study the photoluminescence internal quantum efficiency (IQE) and recombination dynamics in a pair of polar and non-polar InGaN/GaN quantum well (QW) light-emitting diode (LED) structures as a function of excess carrier density and temperature. In the polar LED at 293 K, the variation of radiative and non-radiative lifetimes is well described by a modified ABC type model which accounts for the background carrier concentration in the QWs due to unintentional doping. As the temperature is reduced, the sensitivity of the radiative lifetime to excess carrier density becomes progressively weaker. We attribute this behaviour to the reduced mobility of the localised electrons and holes at low temperatures, resulting in a more monomolecular like radiative process. Thus we propose that in polar QWs, the degree of carrier localisation determines the sensitivity of the radiative lifetime to the excess carrier density. In the non-polar LED, the radiative lifetime is independent of excitation density at room temperature, consistent with a wholly excitonic recombination mechanism. These findings have significance for the interpretation of LED efficiency data within the context of the ABC recombination model.

  3. Effects of growth temperature on nonpolar a-plane InN grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Rajpalke, Mohana K.; Bhat, Thirumaleshwara N.; Krupanidhi, S.B. [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Roul, Basanta [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore-560013 (India); Kumar, Mahesh [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Centre of Excellence in Information and Communication Technology, Indian Institute of Technology, Jodhpur-342011 (India); Sinha, Neeraj [Office of Principal Scientific Advisor, Government of India, New Delhi 110011 (India); Department of Materials Science, Gulbarga University, Gulbarga 585 106 (India); Jali, V.M. [Department of Physics, Gulbarga University, Gulbarga 585 106 (India)

    2014-04-15

    Nonpolar a-plane InN films were grown on r-plane sapphire substrate by plasma assisted molecular beam epitaxy with GaN underlayer. Effect of growth temperature on structural, morphological, and optical properties has been studied. The growth of nonpolar a-plane (1 1 -2 0) orientation was confirmed by high resolution X-ray diffraction study. The film grown at 500 C shows better crystallinity with the rocking curve FWHM 0.67 and 0.85 along [0 0 0 1] and [1 -1 0 0] directions, respectively. Scanning electron micrograph shows formation of Indium droplets at higher growth temperature. Room tem-perature absorption spectra show growth temperature dependent band gap variation from 0.74-0.81 eV, consistent with the expected Burstein-Moss effect. The rectifying behaviour of the I-V curve indicates the existence of Schottky barrier at the InN and GaN interface. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Chemically assisted ion beam etching of laser diode facets on nonpolar and semipolar orientations of GaN

    Science.gov (United States)

    Kuritzky, L. Y.; Becerra, D. L.; Saud Abbas, A.; Nedy, J.; Nakamura, S.; DenBaars, S. P.; Cohen, D. A.

    2016-07-01

    We demonstrate a vertical (beam etching (CAIBE) in Cl2 chemistry that is suitable for forming laser diode (LD) facets on nonpolar and semipolar oriented III-nitride devices. The etch profiles were achieved with photoresist masks and optimized CAIBE chamber conditions including the platen tilt angle and Cl2 flow rate. Co-loaded studies showed similar etch rates of ˜60 nm min-1 for (20\\bar{2}\\bar{1}),(20\\bar{2}1), and m-plane orientations. The etched surfaces of LD facets on these orientations are chemically dissimilar (Ga-rich versus N-rich), but were visually indistinguishable, thus confirming the negligible orientation dependence of the etch. Continuous-wave blue LDs were fabricated on the semipolar (20\\bar{2}\\bar{1}) plane to compare CAIBE and reactive ion etch (RIE) facet processes. The CAIBE process resulted in LDs with lower threshold current densities due to reduced parasitic mirror loss compared with the RIE process. The LER, degree of verticality, and model of the 1D vertical laser mode were used to calculate a maximum uncoated facet reflection of 17% (94% of the nominal) for the CAIBE facet. The results demonstrate the suitability of CAIBE for forming high quality facets for high performance nonpolar and semipolar III-N LDs.

  5. Effects of n-alkanes on compositions of cellular non-polar lipids in Aspergillus sp. isolated from soils

    Energy Technology Data Exchange (ETDEWEB)

    Miyazima, M.; Iida, M.; Iizuka, H.

    1985-01-01

    A strain of hydrocarbon-using filamentous fungi, Aspergillus sp. No. 250-2, was grown on n-alkanes (C/sub 11/ to C/sub 16/) and glucose as the sole carbon and energy sources, and the distribution of cellular non-polar lipids was determined. The non-polar lipids were examined by thin-layer chromatography; they were sterols, sterol esters, diglycerides, triglycerides, and free fatty acids, and the major lipids were free fatty acids and triglycerides on all substrates. Free fatty acids were mainly even-chain saturated acids on all substrates. When grown on n-C/sub 11/ to 15, the unsaturated fatty acids were mainly incorporated into triglyceride, but there were saturated fatty acids with n-C/sub 16/ and glucose. The proportion of C/sub 16/.0 acid was increased markedly in n-C/sub 16/-grown cells, but C18:0 acid was increased in glucose-grown cells. Compositions of odd-chain fatty acids were slightly increased in both free fatty acids and triglycerides from n-C/sub 15/-grown cells. It is suggested that n-alkanes as substrates influenced the incorporation of fatty acids into triglyceride.

  6. Mechanism and energetics of O and O2 adsorption on polar and non-polar ZnO surfaces

    Science.gov (United States)

    Gorai, Prashun; Seebauer, Edmund G.; Ertekin, Elif

    2016-05-01

    Polar surfaces of semiconducting metal oxides can exhibit structures and chemical reactivities that are distinct from their non-polar surfaces. Using first-principles calculations, we examine O adatom and O2 molecule adsorption on 8 different known ZnO reconstructions including Zn-terminated (Zn-ZnO) and O-terminated (O-ZnO) polar surfaces, and non-polar surfaces. We find that adsorption tendencies are largely governed by the thermodynamic environment, but exhibit variations due to the different surface chemistries of various reconstructions. The Zn-ZnO surface reconstructions which appear under O-rich and H-poor environments are found to be most amenable to O and O2 adsorption. We attribute this to the fact that on Zn-ZnO, the O-rich environments that promote O adsorption also simultaneously favor reconstructions that involve adsorbed O species. On these Zn-ZnO surfaces, O2 dissociatively adsorbs to form O adatoms. By contrast, on O-ZnO surfaces, the O-rich conditions required for O or O2 adsorption tend to promote reconstructions involving adsorbed H species, making further O species adsorption more difficult. These insights about O2 adsorption on ZnO surfaces suggest possible design rules to understand the adsorption properties of semiconductor polar surfaces.

  7. Conversion of polar and non-polar algae oil lipids to fatty acid methyl esters with solid acid catalysts--A model compound study.

    Science.gov (United States)

    Asikainen, Martta; Munter, Tony; Linnekoski, Juha

    2015-09-01

    Bio-based fuels are becoming more and more important due to the depleting fossil resources. The production of biodiesel from algae oil is challenging compared to terrestrial vegetable oils, as algae oil consists of polar fatty acids, such as phospholipids and glycolipids, as well as non-polar triglycerides and free fatty acids common in vegetable oils. It is shown that a single sulphonated solid acid catalyst can perform the esterification and transesterification reactions of both polar and non-polar lipids. In mild reaction conditions (60-70 °C) Nafion NR50 catalyst produces methyl palmitate (FAME) from the palmitic acid derivatives of di-, and tri-glyceride, free fatty acid, and phospholipid with over 80% yields, with the glycolipid derivative giving nearly 40% yields of FAME. These results demonstrate how the polar and non-polar lipid derivatives of algal oil can be utilised as feedstocks for biodiesel production with a single catalyst in one reaction step.

  8. Structural stability of scandium on nonpolar GaN (112{sup ¯}0) and (101{sup ¯}0) surfaces: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    González-Hernández, Rafael, E-mail: rhernandezj@uninorte.edu.co [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); Martínez, Gustavo; López-Perez, William [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla (Colombia); Rodriguez, Jairo Arbey [Grupo de Estudio de Materiales, Departamento de Física, Universidad Nacional de Colombia, Bogotá (Colombia)

    2014-01-01

    First-principles calculations based on density-functional theory have been implemented to study the scandium (Sc) adsorption and incorporation on nonpolar GaN (112{sup ¯}0) and (101{sup ¯}0) surfaces. It is found that Sc adatom prefers to reside at bridge positions, between the hollow and top sites, on both GaN nonpolar surfaces. In addition, calculating the relative surface energy of several Sc configurations, we constructed a phase diagram showing the energetically most stable surfaces as a function of the Ga chemical potentials. Based on these results, we have found that incorporation of Sc adatoms in the Ga-substitutional site is energetically more favorable compared with the adsorption on the top layers. This effect leads to the formation of ScN interlayers on nonpolar GaN (112{sup ¯}0) and (101{sup ¯}0) surfaces, which reduces the dislocation densities between GaN and ScN.

  9. Stable nonpolar solvent droplet generation using a poly(dimethylsiloxane) microfluidic channel coated with poly-p-xylylene for a nanoparticle growth.

    Science.gov (United States)

    Lim, Heejin; Moon, SangJun

    2015-08-01

    Applications of microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS) have been limited to water-based analysis rather than nonpolar solvent based chemistry due to a PDMS swelling problem that occurs by the absorption of the solvents. The absorption and swelling causes PDMS channel deformation in shape, and changes the cross sectional area making it difficult to control the flow rate and concentrations of solution in PDMS microfluidic channels. We propose that poly-p-xylylene polymers (parylenes) are chemical vapors deposited on the surfaces of PDMS channels that alleviate the effect of solvents on the absorption and swelling. The parylene coated surface sustains 3 h with a small volumetric change (less than 22 % of PDMS swelling ratio). By generating an air-nonpolar solvent interface based on droplets in PDMS channel, we confirmed poly-p-xylylene coated PDMS microfluidic channels have the potential to be applicable to nanocrystal growth using nonpolar solvents.

  10. Media Education Initiatives by Media Organizations: The Uses of Media Literacy in Hong Kong Media

    Science.gov (United States)

    Chu, Donna; Lee, Alice Y. L.

    2014-01-01

    As more media organizations have engaged in media education, this paper investigates the goals and practices of these activities. This article coins media education initiatives by media organizations with the term "media-organization media literac"y (MOML). Four MOML projects in Hong Kong were selected for examination. Built on critical…

  11. Media matters.

    Science.gov (United States)

    Martinez, L M

    1995-01-01

    The impact of the mass media on woman's status was addressed at two 1995 conferences: the Fourth World Conference on Women, held in Beijing, China, and the Congress of the World Association for Christian Communication, held in Puebla, Mexico. The globalization process facilitated by the mass media has served to increase the power of patriarchy, with no advantages to the cause of women's rights. Coverage of popular movements has been suppressed out of deference to male-controlled governments. Coverage of the Beijing Conference highlighted celebrities and personal stories, to the exclusion of the economic and political issues under debate. Television has commodified women, reinforcing their oppression. On the other hand, the alternative media, which tend to be decentralized, democratic, low-cost, and low in technology, are presenting women as subjects rather than objects and deconstructing gender stereotypes. Of concern, however, is the tendency of computer technology to widen the gap between social classes and developed and developing countries. Women must use information networks to disseminate information on women's rights and strengthen the links between women throughout the world.

  12. Effects of Si-doping on structural, electrical, and optical properties of polar and non-polar AlGaN epi-layers

    Science.gov (United States)

    Yang, Hongquan; Zhang, Xiong; Wang, Shuchang; Wang, Yi; Luan, Huakai; Dai, Qian; Wu, Zili; Zhao, Jianguo; Cui, Yiping

    2016-08-01

    The polar (0001)-oriented c-plane and non-polar (11 2 bar 0) -oriented a-plane wurtzite AlGaN epi-layers were successfully grown on polar (0001)-oriented c-plane and semi-polar (1 1 bar 02) -oriented r-plane sapphire substrates, respectively with various Si-doping levels in a low pressure metal organic chemical vapor deposition (MOCVD) system. The morphological, structural, electrical, and optical properties of the polar and non-polar AlGaN epi-layers were studied with scanning electron microscopy (SEM), X-ray diffraction (XRD), Hall effect, and Raman spectroscopy. The characterization results show that Si dopants incorporated into the polar and non-polar AlGaN films induced a relaxation of compressive residual strain and a generation of biaxial tensile strain on the surface in consequence of the dislocation climbing. In particular, it was found that the Si-induced compressive strain relaxation in the non-polar AlGaN samples can be promoted by the structural anisotropy as compared with the polar counterparts. The gradually increased relaxation of compressive residual strain in both polar and non-polar AlGaN samples with increasing Si-doping level was attributed to the Si-induced enhancement in the opportunity for the dislocations to interact and annihilate. This implies that the crystal quality for both polar and non-polar AlGaN epi-layers can be remarkably improved by Si-doping.

  13. An Analytic Equation of State Based on SAFT-CP for Binary Non-Polar Alkane Mixtures Across the Critical Point

    Institute of Scientific and Technical Information of China (English)

    周文来; 密建国; 贺刚; 于燕梅; 陈健

    2003-01-01

    The description using an analytic equation of state of thermodynamic properties near the critical points of fluids and their mixtures remains a challenging problem in the area of chemical engineering. Based on the statistical associating fluid theory across the critical point (SAFT-CP), an analytic equation of state is established in this work for non-polar mixtures. With two binary parameters, this equation of state can be used to calculate not only vapor-liquid equilibria but also critical properties of binary non-polar alkane mixtures with acceptable deviations.

  14. Use of polar and nonpolar fractions as additional information sources for studying thermoxidized virgin olive oils by FTIR

    Directory of Open Access Journals (Sweden)

    Tena, N.

    2014-09-01

    Full Text Available Fourier transform infrared (FTIR spectroscopy has been proposed to study the degradation of virgin olive oils (VOO in samples undergoing thermoxidation. The polar and nonpolar fractions of oxidized oils have been analyzed by FTIR to provide further information on the minor spectral changes taking place during thermoxidation. This information assists in the interpretation of the spectra of the samples. For this purpose polar and nonpolar fractions of 47 VOO samples thermoxidized (190 °C in a fryer were analyzed by FTIR. The time-course change of the band area assigned to single cis double bonds was explained by their correlation with the decrease in oleic acid (adjusted-R2=0.93. The bands assigned to the hydroxyl groups and the first overtone of ester groups was better studied in the spectra collected for the polar and nonpolar fractions, respectively. The bands assigned to peroxide, epoxy, tertiary alcohols and fatty acids were clearly observed in the spectra of the polar fraction while they are not noticeable in the spectra of the oils.La espectroscopía de infrarrojos por transformada de Fourier (FTIR se ha propuesto para estudiar la degradación de los aceites de oliva vírgenes (AOV sujetas a termoxidación. Las fracciones polares y no polares de aceites oxidados se analizaron mediante FTIR para obtener más información sobre los cambios espectrales menores que tienen lugar durante la termoxidación. Esa información ayuda en la interpretación de los espectros de las muestras puras. Con este objetivo, fracciones polares y no polares de 47 AOV termoxidados (190 °C en una freidora se analizaron mediante FTIR. La banda asignada a dobles enlaces cis se explica por su correlación con la disminución de ácido oleico (R2-ajustado=0,93. Las bandas asignadas a los grupos hidroxilos y del primer sobretono de los grupos éster se estudió mejor en los espectros recogidos para la fracción polar y no polar, respectivamente. Grupos asignados a per

  15. Microstructure of non-polar GaN on LiGaO2 grown by plasma-assisted MBE.

    Science.gov (United States)

    Shih, Cheng-Hung; Huang, Teng-Hsing; Schuber, Ralf; Chen, Yen-Liang; Chang, Liuwen; Lo, Ikai; Chou, Mitch Mc; Schaadt, Daniel M

    2011-06-15

    We have investigated the structure of non-polar GaN, both on the M - and A-plane, grown on LiGaO2 by plasma-assisted molecular beam epitaxy. The epitaxial relationship and the microstructure of the GaN films are investigated by transmission electron microscopy (TEM). The already reported epi-taxial relationship and for M -plane GaN is confirmed. The main defects are threading dislocations and stacking faults in both samples. For the M -plane sample, the density of threading dislocations is around 1 × 1011 cm-2 and the stacking fault density amounts to approximately 2 × 105 cm-1. In the A-plane sample, a threading dislocation density in the same order was found, while the stacking fault density is much lower than in the M -plane sample.

  16. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    Science.gov (United States)

    Smirnov, A. M.; Young, E. C.; Bougrov, V. E.; Speck, J. S.; Romanov, A. E.

    2016-01-01

    We calculate the critical thickness for misfit dislocation (MD) formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs). It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ˜70° for Al0.13Ga0.87N/GaN ( h 0 h ¯ 1 ) semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1-xN/GaN heterostructures.

  17. Efficient Extraction of Astaxanthin from Phaffia rhodozyma with Polar and Non-polar Solvents after Acid Washing

    Institute of Scientific and Technical Information of China (English)

    YIN Chunhua; YANG Shuzhen; LIU Xiaolu; YAN Hai

    2013-01-01

    method of extracting astaxanthin from Phaffia rhodozyma with various solvents after acid washing was investigated.The extraction efficiency was distinctly increased after acid washing of P.rhodozyma cells.When the concentration of HCl was 0.4 mol·L-,the highest extraction efficiency of astaxanthin was achieved which was about three times higher than the control.Acetone or benzene as single polar or non-polar solvent was the most effective solvent in our research.With a combination of isopropanol and n-hexane (volume ratio of 2 ∶ 1),the maximal extraction efficiency was achieved,approximately 60% higher than that obtained with a single solvent.The liquid-solid ratio and the extracting time were also optimized.Under the optimum extraction conditions,the extraction yield of astaxanthin exceeded 98%.

  18. Simultaneous analysis method for polar and non-polar ginsenosides in red ginseng by reversed-phase HPLC-PAD.

    Science.gov (United States)

    Lee, Sa-Im; Kwon, Ha-Jeong; Lee, Yong-Moon; Lee, Je-Hyun; Hong, Seon-Pyo

    2012-02-23

    The paper describes the development of a simultaneous determination method for polar and non-polar ginsenosides in red ginseng with a reversed-phase high-performance liquid chromatography-pulsed amperometric detection method. This method could be applied directly without any pretreatment steps and enabled the performance of highly sensitive analysis within 1h. The detection (S/N=3) and quantification (S/N=10) limits for the ginsenosides ranged 0.02-0.10 ng and 0.1-0.3 ng, respectively. The linear regression coefficients ranged 0.9975-0.9998. Intra- and inter-day precisions were <9.91%. The mean recoveries ranged 98.08-103.06%. The total amount of ginsenosides in the hairy root of red ginseng was higher than that in the main root.

  19. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    KAUST Repository

    Smirnov, A. M.

    2016-01-20

    We calculate the critical thickness for misfit dislocation (MD) formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs). It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ∼70° for Al0.13Ga0.87N/GaN (h0h̄ 1) semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1−xN/GaN heterostructures.

  20. High-resolution field desorption/ionization fourier transform ion cyclotron resonance mass analysis of nonpolar molecules.

    Science.gov (United States)

    Schaub, Tanner M; Hendrickson, Christopher L; Qian, Kuangnan; Quinn, John P; Marshall, Alan G

    2003-05-01

    We report the first field desorption ionization broadband high-resolution (m/Deltam(50%) approximately 65 000) mass spectra. We have interfaced a field ionization/field desorption source to a home-built 9.4-T FT-ICR mass spectrometer. The instrumental configuration employs convenient sample introduction (in-source liquid injection) and external ion accumulation. We demonstrate the utility of this configuration by generating high-resolution positive-ion mass spectra of C(60) and a midboiling crude oil distillate. The latter contains species not accessible by common soft-ionization methods, for example, low-voltage electron ionization, electrospray ionization, and matrix-assisted laser desorption/ionization. The present work demonstrates significant advantages of FI/FD FT-ICR MS for analysis of nonpolar molecules in complex mixtures.

  1. Interaction of Polar and Nonpolar Organic Pollutants with Soil Organic Matter: Sorption Experiments and Molecular Dynamics Simulation

    CERN Document Server

    Ahmed, Ashour A; Aziz, Saadullah G; Hilal, Rifaat H; Elroby, Shaaban A; Al-Youbi, Abdulrahman O; Leinweber, Peter; Kühn, Oliver

    2014-01-01

    The fate of organic pollutants in the environment is influenced by several factors including the type and strength of their interactions with soil components especially SOM. However, a molecular level answer to the question How organic pollutants interact with SOM? is lacking. In order to explore mechanisms of this interaction, we have developed a new SOM model followed by carrying out molecular dynamics (MD) simulations in parallel with sorption experiments. The new SOM model comprises free SOM functional groups (carboxylic acid and naphthalene) as well as SOM cavities (with two different sizes), representing the soil voids, containing the same SOM functional groups. To examine the effect of the hydrophobicity on the interaction, the organic pollutants hexachlorobenzene (HCB, non-polar) and sulfanilamide (SAA, polar) were considered. The experimental and the theoretical outcomes explored four major points regarding sorption of SAA and HCB on soil. 1. The interaction depends on the SOM chemical composition mo...

  2. Critical thickness for the formation of misfit dislocations originating from prismatic slip in semipolar and nonpolar III-nitride heterostructures

    Directory of Open Access Journals (Sweden)

    A. M. Smirnov

    2016-01-01

    Full Text Available We calculate the critical thickness for misfit dislocation (MD formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs. It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ∼70° for Al0.13Ga0.87N/GaN ( h 0 h ̄ 1 semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1−xN/GaN heterostructures.

  3. Effects of organic solvents and substrate binding on trypsin in acetonitrile and hexane media.

    Science.gov (United States)

    Meng, Yanyan; Yuan, Yuan; Zhu, Yanyan; Guo, Yanzhi; Li, Menglong; Wang, Zhimeng; Pu, Xuemei; Jiang, Lin

    2013-09-01

    In this work, we used molecular dynamic (MD) simulation to study trypsin with and without a six-amino-acid peptide bound in three different solvents (water, acetonitrile and hexane) in order to provide molecular information for well understanding the structure and function of enzymes in non-aqueous media. The results show that the enzyme is more compact and less native-like in hexane than in the other two polar solvents. The substrate could stabilize the native protein structure in the two polar media, but not in the non-polar hexane. There are no significant differences in the conformation of the S1 pocket upon the substrate binding in water and acetonitrile media while a reverse behavior is observed in hexane media, implying a possible induced fit binding mechanism in the non-polar media. The substrate binding enhances the stability of catalytic H-bond network since it could expel the solvent molecules from the active site. The enzyme and the substrate appear to be more appropriate to the reactive conformation in the organic solvents compared with aqueous solution. There is much greater substrate binding strength in hexane media than the water and acetonitrile ones since the polar solvent significantly weakens electrostatic interactions, which are observed to be the main driving force to the binding. In addition, some residues of the S1 pocket could remain favorable contribution to the binding despite the solvent change, but with differences in the contribution extent, the number and the type of residues between the three media.

  4. Modeling the structure and absorption spectra of stilbazolium merocyanine in polar and nonpolar solvents using hybrid QM/MM techniques.

    Science.gov (United States)

    Murugan, N Arul; Kongsted, Jacob; Rinkevicius, Zilvinas; Aidas, Kestutis; Ågren, Hans

    2010-10-28

    We have performed Car-Parrinello mixed quantum mechanics/molecular mechanics (CP-QM/MM) calculations for stilbazolium merocyanine (SM) in polar and nonpolar solvents in order to explore the role of solute molecular geometry, solvation shell structure, and different interaction mechanisms on the absorption spectra and its dependence on solvent polarity. On the basis of the average bond length values and group charge distributions, we find that the SM molecule remains in a neutral quinonoid form in chloroform (a nonpolar solvent) while it transforms to a charge-separated benzenoid form in water (a polar solvent). Based on a quantum mechanical/molecular mechanical response technique, with different MM descriptions for the water environment, absorption spectra were obtained as averages over configurations derived from the CP-QM/MM simulations. We show that for SM in water the solute polarization plays a major role in predictions of the λ(max) and solvatochromic shift and that once this effect is included the contributions from solvent polarization and intermolecular charge transfer become less important. For SM in chloroform and water solvents, we have also performed absorption spectra calculations using a polarizable continuum model in order to address its relative performance compared to the QM/MM response technique. In the case of SM in water, our study supports the notion that, in order to predict accurate absorption spectra and solvatochromic shifts, it is important to use a discrete description of the solvent when it, as in water, is involved in site-specific interaction with the solute molecule. The technique is thus shown to outperform the more conventional polarizable continuum model in predicting the solvatochromic shift.

  5. Vacuum-UV spectroscopy of interstellar ice analogs. II. Absorption cross-sections of nonpolar ice molecules

    Science.gov (United States)

    Cruz-Diaz, G. A.; Muñoz Caro, G. M.; Chen, Y.-J.; Yih, T.-S.

    2014-02-01

    Context. Dust grains in cold circumstellar regions and dark-cloud interiors at 10-20 K are covered by ice mantles. A nonthermal desorption mechanism is invoked to explain the presence of gas-phase molecules in these environments, such as the photodesorption induced by irradiation of ice due to secondary ultraviolet photons. To quantify the effects of ice photoprocessing, an estimate of the photon absorption in ice mantles is required. In a recent work, we reported the vacuum-ultraviolet (VUV) absorption cross sections of nonpolar molecules in the solid phase. Aims: The aim was to estimate the VUV-absorption cross sections of nonpolar molecular ice components, including CH4, CO2, N2, and O2. Methods: The column densities of the ice samples deposited at 8 K were measured in situ by infrared spectroscopy in transmittance. VUV spectra of the ice samples were collected in the 120-160 nm (10.33-7.74 eV) range using a commercial microwave-discharged hydrogen flow lamp. Results: We found that, as expected, solid N2 has the lowest VUV-absorption cross section, which about three orders of magnitude lower than that of other species such as O2, which is also homonuclear. Methane (CH4) ice presents a high absorption near Ly-α (121.6 nm) and does not absorb below 148 nm. Estimating the ice absorption cross sections is essential for models of ice photoprocessing and allows estimating the ice photodesorption rates as the number of photodesorbed molecules per absorbed photon in the ice. Data can be found at http://ghosst.osug.fr/

  6. Indium incorporation in semipolar (20 2 ̅ 1) and nonpolar (10 1 ̅ 0) InGaN grown by plasma assisted molecular beam epitaxy

    Science.gov (United States)

    Sawicka, M.; Feduniewicz-Żmuda, A.; Kryśko, M.; Turski, H.; Muziol, G.; Siekacz, M.; Wolny, P.; Skierbiszewski, C.

    2017-02-01

    Semipolar (20 2 ̅ 1) , nonpolar m-plane (10 1 ̅ 0) and polar c-plane (0001) GaN and InGaN layers were grown by plasma-assisted molecular beam epitaxy. The surface of semipolar and nonpolar GaN grown under Ga-rich conditions is very smooth. The indium incorporation efficiency in InGaN layers grown under In-rich growth conditions is studied on three surface orientations (i) as a function of temperature from 570 to 650 °C and (ii) for varied active nitrogen flux from 0.41 to 2.03 μm/h. The In content follows the relation (10 1 ̅ 0) experiments. Indium composition in InGaN layers can be increased (i) by the decrease of the growth temperature and (ii) increase of the applied nitrogen flux for all studied surface orientations. Additionally, surface morphology of semipolar, nonpolar and c-polar InGaN layers grown at 650, 640 and 620 °C is compared. No increase in surface roughness for semipolar and nonpolar InGaN was observed in contrast to c-plane counterparts.

  7. Non-polar In x Ga1-x N/GaN quantum dots: impact of dot size and shape anisotropies on excitonic and biexcitonic properties

    Science.gov (United States)

    Kanta Patra, Saroj; Schulz, Stefan

    2017-01-01

    In this work, we present a theoretical analysis of the built-in potential, the excitonic and biexcitonic properties of non-polar InGaN/GaN quantum dots by means of self-consistent Hartree calculations using \\mathbf{k}\\centerdot \\mathbf{p} theory. Special attention is paid to the impact of dot size and shape anisotropies on the results. Our calculations reveal that even though non-polar InGaN/GaN quantum dots exhibit strongly reduced built-in fields when compared to c-plane dots, the excitonic and biexcitonic properties are significantly affected by these residual fields. Furthermore, changes in the built-in field when the geometrical dot features are modified, result in an unusual variation of the exciton binding energy. All these findings highlight that the dot geometry significantly affects electronic and optical properties of non-polar InGaN/GaN systems. This is further supported by comparing our theoretical data with experimental literature results. Here, we analyze also trends in exciton and biexciton binding energies and discuss the potential use of non-polar InGaN/GaN dots for entangled photon emission via the time reordering scheme.

  8. Defensive Armor of Potato Tubers: Nonpolar Metabolite Profiling, Antioxidant Assessment, and Solid-State NMR Compositional Analysis of Suberin-Enriched Wound-Healing Tissues.

    Science.gov (United States)

    Dastmalchi, Keyvan; Kallash, Linda; Wang, Isabel; Phan, Van C; Huang, Wenlin; Serra, Olga; Stark, Ruth E

    2015-08-05

    The cultivation, storage, and distribution of potato tubers are compromised by mechanical damage and suboptimal healing. To investigate wound-healing progress in cultivars with contrasting russeting patterns, metabolite profiles reported previously for polar tissue extracts were complemented by GC/MS measurements for nonpolar extracts and quantitative (13)C NMR of interfacial solid suspensions. Potential marker compounds that distinguish cultivar type and wound-healing time point included fatty acids, fatty alcohols, alkanes, glyceryl esters, α,ω-fatty diacids, and hydroxyfatty acids. The abundant long-chain fatty acids in nonpolar extracts and solids from the smooth-skinned Yukon Gold cultivar suggested extensive suberin biopolymer formation; this hypothesis was supported by high proportions of arenes, alkenes, and carbonyl groups in the solid and among the polar markers. The absence of many potential marker classes in nonpolar Atlantic extracts and interfacial solids suggested a limited extent of suberization. Modest scavenging activities of all nonpolar extracts indicate that the majority of antioxidants produced in response to wounding are polar.

  9. Geographic Media Literacy

    Science.gov (United States)

    Lukinbeal, Chris

    2014-01-01

    While the use of media permeates geographic research and pedagogic practice, the underlying literacies that link geography and media remain uncharted. This article argues that geographic media literacy incorporates visual literacy, information technology literacy, information literacy, and media literacy. Geographic media literacy is the ability…

  10. Measuring News Media Literacy

    Science.gov (United States)

    Maksl, Adam; Ashley, Seth; Craft, Stephanie

    2015-01-01

    News media literacy refers to the knowledge and motivations needed to identify and engage with journalism. This study measured levels of news media literacy among 500 teenagers using a new scale measure based on Potter's model of media literacy and adapted to news media specifically. The adapted model posits that news media literate individuals…

  11. Influence of Nonpolar Substances on the Extraction Efficiency of Six Alkaloids in Zoagumhwan Investigated by Ultra Performance Liquid Chromatography and Photodiode Array Detection

    Directory of Open Access Journals (Sweden)

    Shijing Liu

    2012-11-01

    Full Text Available A reverse phase ultra performance liquid chromatography and photodiode array (UPLC-PDA detection method was established for the determination of six alkaloids in Zoagumhwan (ZGW, and further for investigating the influence of nonpolar substances on the extraction efficiency of these alkaloids. The method was based on a BEH C18 (50 mm × 2.1 mm, 1.7 μm column and mobile phase of aqueous phosphoric acid and acetonitrile including 0.05% buffer solution under gradient elution. ZGW samples of ZGW I, II, III and IV were obtained and prepared by pre-processing the crude materials of Coptidis rhizoma and Evodiae fructus using four technologies, namely direct water decoction, removal of nonpolar substances in Evodiae fructus by supercritical fluid extraction (SFE, removal of nonpolar substances in ZGW by SFE and removal of nonpolar substances in ZGW by steam distillation. The developed and validated UPLC-PDA method was precise, accurate and sensitive enough based on the facts that the six alkaloids showed good regression (r > 0.9998, the limit of detections and quantifications for six alkaloids were less than 28.8 and 94.5 ng/mL, respectively, and the recovery was in the range of 98.56%–103.24%. The sequence of the total contents of six alkaloids in these samples was ZGW II > ZGW IV > ZGW III > ZGW I. ZGW II, in which nonpolar substances, including essential oils, were firstly removed from Evodiae fructus by SFE, had the highest content of the total alkaloids, indicating that extraction efficiency of the total alkaloids could be remarkably increased after Evodiae fructus being extracted by SFE.

  12. Media Literacy in Times of Media Divides

    Directory of Open Access Journals (Sweden)

    Kaja Žuran

    2013-12-01

    Full Text Available We live in a post-modern society, an information society, a society based around knowledge and participation, and above all in a media society. In a media culture where media holds a dominant position, we cannot overlook the emerging idea of a ‘media divide’ within the frame of media education, media literate individuals and the expansion of the traditional concept of media literacy. Firstly, we are in an era of technological revolution, and it is time to consider the meaning and function of media and how we experience it in our everyday life. Secondly, as a society we are subject to intense media invasion and we all need to learn how to use it to our benefit and apply a critical and autonomous perspective towards selecting media content. Otherwise the media divide between the media literate and illiterate will widen; but is there even a chance to overcome the supposed divide between those who are formally media educated and those who are not?

  13. Social media metrics

    OpenAIRE

    Balvín, Radek

    2013-01-01

    With growing amount of data produced by users on social media the need of extraction of relevant data for marketing, research and other uses grows as well. The bachelor thesis named "Social media metrics" presents the issues of monitoring, measurement and metrics of social media. In the research part it also maps and captures the present Czech practice in measurement and monitoring of social media. I also rate the use of social media monitoring tools and usual methods of social media measurem...

  14. Social media management and media environment

    Directory of Open Access Journals (Sweden)

    Šiđanin Iva

    2012-01-01

    Full Text Available The paper deals with the system of services that social media management can offer to a variety of users. As social media systems are emerging, social media management can strengthen teams in social media and help to manage numerous social channels and distribution of social information from one place. Social media management is a system of procedures that are used to manage the flow of information in the environment of social media. This involves connecting with social media like Facebook, Twitter, LinkedIn, Plaxo, Ecademy, YouTube and many others, then the aggregation and management of social data. Social media management services are analysed through various fields, such as managing multiple social media profiles, mail scheduling and filtering, reporting and analytics. Social media management enables managing personal business through social media, which contributes to a significant reduction in expenditures. The paper also discusses the importance of social media management in marketing activities and various forms of social promotion, which allow companies to easily reach their customers.

  15. Advertising on social media

    Directory of Open Access Journals (Sweden)

    Sumit Goyal

    2013-05-01

    Full Text Available This communication reports the latest trends of advertising on social media. Social media advertising means to gain traffic or attention of online users through social media sites. Today, when a user thinks about buying something, he first comes to the internet, searches for that product, compares its price with other competing brands and takes a decision, which one to buy. In this write-up, author has discussed many aspects concerning advertising through social media, viz., what is social media? What is the impact of social media on mainstream media, why to advertise on social media? and what should be the strategy for advertising on social media. The author is of the view that in the year 2013, $4 billion will be spent on social media advertising across the globe and social media industry will generate over 1,00,000 new jobs all around the world.

  16. Otitis media with effusion

    Science.gov (United States)

    OME; Secretory otitis media; Serous otitis media; Silent otitis media; Silent ear infection; Glue ear ... Kerschner JE, Preciado D. Otitis media. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: ...

  17. Why Media Matter

    Science.gov (United States)

    Locatis, Craig

    2007-01-01

    Whether media affect learning has been debated for decades. The discussion of media's effectiveness has raised questions about the usefulness of comparison studies, not only in assessing applications of technology but in other areas as well. Arguments that media do not affect learning are re-examined and issues concerning media effects on expert…

  18. Media Violence and Children.

    Science.gov (United States)

    Groebel, Jo

    1998-01-01

    Presents the results of the UNESCO global study on media violence and children which was conducted between 1996 and 1997. Highlights include the role of the media, media heroes as role models, media violence and aggression, differences by gender, rural versus urban environments, the pervasiveness of television, and recommendations. (Author/LRW)

  19. Can Nonpolar Polyisobutylenes be Measured by Electrospray Ionization Mass Spectrometry? Anion-Attachment Proved to be an Appropriate Method

    Science.gov (United States)

    Nagy, Lajos; Nagy, Tibor; Deák, György; Kuki, Ákos; Purgel, Mihály; Narmandakh, Mijid; Iván, Béla; Zsuga, Miklós; Kéki, Sándor

    2016-03-01

    Polyisobutylenes (PIBs) with different end-groups including chlorine, exo-olefin, hydroxyl, and methyl prepared from aliphatic and aromatic initiators were studied by electrospray ionization mass spectrometry (ESI-MS). Independently of the end-groups, presence or absence of aromatic initiator moiety, these PIB derivatives were capable of forming adduct ions with NO3 - and Cl- ions, thus allowing the direct characterization of these compounds in the negative ion mode of ESI-MS. To obtain [PIB + NO3]- and [PIB + Cl]- adduct ions with appreciable intensities, addition of polar solvents such as acetone, 2-propanol, or ethanol to the dichloromethane solution of PIBs was necessary. Furthermore, increasing both the polarity (by increasing the acetone content) and the ion-source temperature give rise to enhanced intensities for both [PIB + NO3]- and [PIB + Cl]- ions. Energy-dependent collision induced dissociation studies (CID) revealed that increasing the collision voltages resulted in the shift of the apparent molecular masses to higher ones. CID studies also showed that dissociation of the [PIB + Cl]- ions requires higher collision energy than that of [PIB + NO3]-. In addition, Density Functional Theory calculations were performed to gain insights into the nature of the interactions between the highly non-polar PIB chains and anions NO3 - and Cl- as well as to determine the zero-point corrected electronic energies for the formation of [PIB + NO3]- and [PIB + Cl]- adduct ions.

  20. Atomistic simulation studies on the dynamics and thermodynamics of nonpolar molecules within the zeolite imidazolate framework-8.

    Science.gov (United States)

    Pantatosaki, Evangelia; Pazzona, Federico G; Megariotis, Gregory; Papadopoulos, George K

    2010-02-25

    Statistical-mechanics-based simulation studies at the atomistic level of argon (Ar), methane (CH(4)), and hydrogen (H(2)) sorbed in the zeolite imidazolate framework-8 (ZIF-8) are reported. ZIF-8 is a product of a special kind of chemical process, recently termed as reticular synthesis, which has generated a class of materials of critical importance as molecular binders. In this work, we explore the mechanisms that govern the sorption thermodynamics and kinetics of nonpolar sorbates possessing different sizes and strength of interactions with the metal-organic framework to understand the outstanding properties of this novel class of sorbents, as revealed by experiments published elsewhere. For this purpose, we have developed an in-house modeling procedure involving calculations of sorption isotherms, partial internal energies, various probability density functions, and molecular dynamics for the simulation of the sorbed phase over a wide range of occupancies and temperatures within a digitally reconstructed unit cell of ZIF-8. The results showed that sorbates perceive a marked energetic inhomogeneity within the atomic framework of the metal-organic material under study, resulting in free energy barriers that give rise to inflections in the sorption isotherms and guide the dynamics of guest molecules.

  1. Non-polar Extraction Effect Analysis of Mimusops elengi (L. bark to Larvae of Aedes aegypti (L.

    Directory of Open Access Journals (Sweden)

    Mutiara Widawati

    2012-11-01

    Full Text Available Tanjung or Mimusops elengi is one of a tree that has many therapeutic effects and has been widely studied as an alternative drug like anti-inflammatory agent, diarrhea, and asthma. This study tested the larvicidal ability of Tanjung bark extract for larvae of Aedes aegypti. The solvent that will be used for Mimusops elengi stem extraction in this research is semi-polar and non-polar solvent, which is ethyl acetate and hexane. The method used in this research was reflux extraction and proceed further with fractionation that has been analyzed by thin layer chromatography. The larvicidal activity of Mimusops elengi extract was tested using a bioassay method that has been established by WHO to determine LC50 and LC9O which can be processed further in order to compare the ejjicacy ofsolvent used. The LC50 value of the extract 1,2 and 3, were each 59.36 ppm, 82.53 ppm, and 110.42 ppm. The experimental results showed that hexane has the most powerful larvicidal ability compared to other extracts.

  2. Relaxation phenomena of polar non-polar liquid mixtures under low and high frequency electric field

    Indian Academy of Sciences (India)

    K Dutta; S K Sit; S Acharyya

    2003-10-01

    Simultaneous calculation of the dipole moment and the relaxation time of a certain number of non-spherical rigid aliphatic polar liquid molecules () in non-polar solvents () under 9.8 GHz electric field is possible from real $'$ and imaginary $''$ parts of the complex relative permittivity $^{*}_{}$. The low frequency and infinite frequency permittivities 0 and ∞ measured by Purohit et al [1,2] and Srivastava and Srivastava [3] at 25, 35 and 30°C respectively are used to obtain static . The ratio of the individual slopes of imaginary and real $'$ parts of high frequency (hf) complex conductivity $^{*}_{}$ with weight fractions at → 0 and the slopes of $''_{}-'_{}$ curves for different s [4] are employed to obtain s. The former method is better in comparison to the existing one as it eliminates polar–polar interaction. The hf s in Coulomb metre (C m) when compared with static and reported s indicate that ss favour the monomer formations which combine to form dimers in the hf electric field. The comparison among s shows that a part of the molecule is rotating under X-band electric field [5]. The theoretical theos from available bond angles and bond moments of the substituent polar groups attached to the parent molecules differ from the measured s and s to establish the possible existence of mesomeric, inductive and electromeric effects in polar liquid molecules.

  3. Temperature dependence of the positronium yields in polar and nonpolar pure liquids; an experimental test of a phenomenological model

    Energy Technology Data Exchange (ETDEWEB)

    Levay, B

    2004-08-02

    A phenomenological model describing the temperature dependence of the positronium yields (I{sub Ps}, %) was tested in pure liquids of different polarity. The investigated solvents were: m-xylene (m-Xy) and iso-octane (i-C8) as aromatic and aliphatic nonpolar hydrocarbons, methanol (MeOH), water and dimethyl formamide as polar solvents with and without OH group. Arrhenius type linear relationship predicted by the model for the lnQ vs 1/T function, where Q=(100/I{sub Ps}-1), was found to be valid in all cases. The slopes of the lines correspond to the activation energy differences ({delta}E{sup *}=E{sub rec}-E{sub Ps}) between the two main competing reaction pathways in the positron spur, i.e., solvent recombination (e{sup -} + M{sup +}) and positronium formation (e{sup -} + e{sup +}). The slopes were positive, i.e., {delta}E{sup *}<0 and E{sub rec}

  4. Short-wavelength, mid- and far-infrared intersubband absorption in nonpolar GaN/Al(Ga)N heterostructures

    Science.gov (United States)

    Lim, Caroline B.; Beeler, Mark; Ajay, Akhil; Lähnemann, Jonas; Bellet-Amalric, Edith; Bougerol, Catherine; Schörmann, Jörg; Eickhoff, Martin; Monroy, Eva

    2016-05-01

    This paper assesses nonpolar m-oriented GaN:Si/Al(Ga)N heterostructures grown on free-standing GaN for intersubband optoelectronics in the short-wavelength, mid- and far-infrared ranges. Characterization results are compared with reference c-plane samples and interpreted by correlation with self-consistent Schrödinger-Poisson calculations. In the near- and mid-infrared regions, we demonstrate m-GaN/Al(Ga)N multi-quantum-wells exhibiting room-temperature intersubband absorption tunable in the range of 1.5-5.8 µm (827-214 meV), the long wavelength limit being set by the second order of the Reststrahlen band in the GaN substrates. Extending the study to the far-infrared region, low-temperature intersubband transitions in the 1.5-9 THz range (6.3-37.4 meV) are observed in larger m-plane GaN/AlGaN multi-quantum-wells, covering most of the 7-10 THz band forbidden to GaAs-based technologies.

  5. Dielectric behaviour of some amides and formamides dissolved in nonpolar solvents under static electric field

    Indian Academy of Sciences (India)

    S Sahoo; S K Sit

    2011-08-01

    Structural and associational aspects of polar amides () like formamide, acetamide, Nmethyl acetamide (NMA), N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMA) and acetanilide dissolved in the nonpolar solvent () benzene or 1,4-dioxan have been estimated from the measured static relative permittivity 0 and high-frequency permittivity ∞ at different weight fractions s of polar solute at 35°C under static electric field using Debye model of polar liquid molecule. The static dipole moments s are compared with s reported from conductivity method and theoretical theos to get exact cal $\\cdot$ theos of the molecules are predicted from the available bond angles and bond moments where difference in electron affinity exists between two adjacent atoms of a polar group due to inductive, mesomeric and electromeric effects in them. Solute–solute molecular association for NMA in benzene and solute–solvent association for other amides are ascertained to arrive at their conformational structures.

  6. Photo-Stimulated Electron Detrapping and the Two-State Model for Electron Transport in Nonpolar Liquids

    CERN Document Server

    Shkrob, I A

    2004-01-01

    In common nonpolar liquids, such as saturated hydrocarbons, a dynamic equilibrium between trapped (localized) and quasifree (extended) states has been postulated for the excess electron (the two-state model). Using time-resolved dc conductivity, the effect of 1064 nm laser photoexcitation of trapped electrons on the charge transport has been observed in liquid n-hexane and methylcyclohexane. The light promotes the electron from the trap into the conduction band of the liquid, instantaneously increasing the conductivity by orders of magnitude. From the analysis of the two-pulse, two-color photoconductivity data, the residence time of the electrons in traps has been estimated as ca. 8.4 ps for n-hexane and ca. 13 ps for methylcyclohexane (at 295 K). The rate of detrapping decreases at lower temperature with an activation energy of ca. 200 meV (280-320 K); the lifetime-mobility product for quasifree electrons scales linearly with the temperature. We suggest that the properties of trapped electrons in hydrocarbon...

  7. Incremental Tuning Up of Fluorous Phenazine Acceptors.

    Science.gov (United States)

    Castro, Karlee P; Clikeman, Tyler T; DeWeerd, Nicholas J; Bukovsky, Eric V; Rippy, Kerry C; Kuvychko, Igor V; Hou, Gao-Lei; Chen, Yu-Sheng; Wang, Xue-Bin; Strauss, Steven H; Boltalina, Olga V

    2016-03-14

    In a simple, one-step direct trifluoromethylation of phenazine with CF3 I we prepared and characterized nine (poly)trifluoromethyl derivatives with up to six CF3 groups. The electrochemical reduction potentials and gas-phase electron affinities show a direct, strict linear relation to the number of CF3 groups, with phenazine(CF3)6 reaching a record-high electron affinity of 3.24 eV among perfluoroalkylated polyaromatics.

  8. Observation of mid-infrared intersubband absorption in non-polar m-plane AlGaN/GaN multiple quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Kotani, Teruhisa, E-mail: kotani.teruhisa@sharp.co.jp [Institute for Nano Quantum Information Electronics, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Life and Environment Laboratories, Sharp Corporation, 2613-1 Ichinomoto-cho, Tenri, Nara 632-8567 (Japan); Arita, Munetaka [Institute for Nano Quantum Information Electronics, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Arakawa, Yasuhiko [Institute for Nano Quantum Information Electronics, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2014-12-29

    Mid-infrared (4.20–4.84 μm) intersubband absorption in non-polar m-plane Al{sub 0.5}Ga{sub 0.5}N/GaN multiple-quantum wells is observed at room temperature. 10 period Al{sub 0.5}Ga{sub 0.5}N/GaN multiple-quantum wells were grown on free-standing m-plane GaN substrates by metalorganic chemical vapor deposition (MOCVD), and the high-quality structural and optical properties are revealed by x-ray diffraction and photoluminescence studies. Through this we have demonstrated that MOCVD grown non-polar m-plane AlGaN/GaN quantum wells are a promising material for mid-infrared intersubband devices.

  9. Understanding social media logic

    OpenAIRE

    José van Dijck; Thomas Poell

    2013-01-01

    Over the past decade, social media platforms have penetrated deeply into the mech­anics of everyday life, affecting people's informal interactions, as well as institutional structures and professional routines. Far from being neutral platforms for everyone, social media have changed the conditions and rules of social interaction. In this article, we examine the intricate dynamic between social media platforms, mass media, users, and social institutions by calling attention to social media lo...

  10. Social media influencer marketing

    OpenAIRE

    Isosuo, Heli

    2016-01-01

    The marketing field is changing simultaneously with the digital world. Social media is getting more and more important to marketers, and there is a need to stand out in the social media noise. Social media influencer marketing could be a good alternative to other types of marketing. A need from the consignor and the interest of the author were the motivations for conducting the study. Sääskilahti Consulting has a social media influencer network Somevaikuttajat, which is offering social media ...

  11. Use of liquid hydrocarbon and amide transfer data to estimate contributions to thermodynamic functions of protein folding from the removal of nonpolar and polar surface from water.

    Science.gov (United States)

    Spolar, R S; Livingstone, J R; Record, M T

    1992-04-28

    This extension of the liquid hydrocarbon model seeks to quantify the thermodynamic contributions to protein stability from the removal of nonpolar and polar surface from water. Thermodynamic data for the transfer of hydrocarbons and organic amides from water to the pure liquid phase are analyzed to obtain contributions to the thermodynamics of folding from the reduction in water-accessible surface area. Although the removal of nonpolar surface makes the dominant contribution to the standard heat capacity change of folding (delta C0fold), here we show that inclusion of the contribution from removal of polar surface allows a quantitative prediction of delta C0fold within the uncertainty of the calorimetrically determined value. Moreover, analysis of the contribution of polar surface area to the enthalpy of transfer of liquid amides provides a means of estimating the contributions from changes in nonpolar and polar surface area as well as other factors to the enthalpy of folding (delta H0fold). In addition to estimates of delta H0fold, this extension of the liquid hydrocarbon model provides a thermodynamic explanation for the observation [Privalov, P. L., & Khechinashvili, N. N. (1974) J. Mol. Biol. 86, 665-684] that the specific enthalpy of folding (cal g-1) of a number of globular proteins converges to a common value at approximately 383 K. Because amounts of nonpolar and polar surface area buried by these proteins upon folding are found to be linear functions of molar mass, estimates of both delta C0fold and delta H0fold may be obtained given only the molar mass of the protein of interest.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Characterization of nonpolar lipids and steroids by using laser-induced acoustic desorption/chemical ionization, atmospheric pressure chemical ionization, and electrospray ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Z; Daiya, S; Kenttämaa, Hilkka I

    Laser-induced acoustic desorption (LIAD) combined with ClMn(H{sub 2}O){sup +} chemical ionization (CI) was tested for the analysis of nonpolar lipids and selected steroids in a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR). The nonpolar lipids studied, cholesterol, 5α-cholestane, cholesta-3,5-diene, squalene, and β-carotene, were found to solely form the desired water replacement product (adduct-H{sub 2}O) upon reaction with the ClMn(H{sub 2}O){sup +} ions. The steroids, androsterone, dehydroepiandrosterone (DHEA), estrone, estradiol, and estriol, also form abundant adduct-H{sub 2}O ions, but less abundant adduct-2H{sub 2}O ions were also observed. Neither (+)APCI nor (+)ESI can ionize the saturated hydrocarbon lipid, cholestane. APCI successfully ionizes the unsaturated hydrocarbon lipids to form exclusively the intact protonated analytes. However, it causes extensive fragmentation for cholesterol and the steroids. The worst case is cholesterol that does not produce any stable protonated molecules. On the other hand, ESI cannot ionize any of the hydrocarbon analytes, saturated or unsaturated. However, ESI can be used to protonate the oxygen-containing analytes with substantially less fragmentation than for APCI in all cases except for cholesterol and estrone. In conclusion, LIAD/ClMn(H{sub 2}O){sup +} chemical ionization is superior over APCI and ESI for the mass spectrometric characterization of underivatized nonpolar lipids and steroids.

  13. Media Pluralism and Diversity

    DEFF Research Database (Denmark)

    challenges for media pluralism policies in the light of a fast changing media environment. The book is unique in that it confronts insights from all parts of the world and from a broad range of disciplines including law, economics, media studies, and sociology.......In the western world, a diverse and pluralistic media landscape is deemed essential for democracy. But how universal is media pluralism as a concept underpinning media policies? To what extent do normative approaches, regulatory dimensions and monitoring systems differ throughout the world......? Adopting a truly global, theoretical and multidisciplinary perspective, Media Pluralism and Diversity advances our understanding of media pluralism across the globe. It compares metrics developed in different parts of the world to assess levels of, or threats to, media pluralism. It identifies common...

  14. Unpacking New Media Literacy

    Directory of Open Access Journals (Sweden)

    Der-Thanq “victor” Chen

    2011-04-01

    Full Text Available The 21st century has marked an unprecedented advancement of new media. New media has become so pervasive that it has penetrated into every aspect of our society. New media literacy plays an essential role for any citizen to participate fully in the 21st century society. Researchers have documented that literacy has evolved historically from classic literacy (reading-writing-understanding to audiovisual literacy to digital literacy or information literacy and recently to new media literacy. A review of literature on media literacy reveals that there is a lack of thorough analysis of unique characteristics of new media and its impacts upon the notion of new media literacy. The purpose of the study is to unpack new media literacy and propose a framework for a systematic investigation of new media literacy.

  15. Mass Media: The Invisible Environment.

    Science.gov (United States)

    Glessing, Robert J.; White, William P.

    This anthology for students of media consists of essays and articles grouped under four topics: media forms, media content, media environments, and "the last word." Media forms deals with the nature of these kinds of media: electronic, print, film, music, and comics, graffiti, and clothing. Media content contains articles on the news, advertising,…

  16. Social Media Reputation

    DEFF Research Database (Denmark)

    Etter, Michael Andreas; Ravasi, Davide; Colleoni, Elanor

    motivational drivers and contextual conditions associated with the formation of narratives in traditional news media and social media influence their content, diffusion, and impact significantly. Our analysis suggests that current theories of media reputation may provide an incomplete representation......Social media enable millions of users to create and disseminate narratives about organizations that increase their public exposure and shape public perceptions. In this paper, we draw on the sociology of news production and research on computer-mediated communication to discuss how different...... of the phenomenon, and highlight theoretically relevant differences and interrelationships between reputational dynamics involving news media and social media....

  17. Nonpolar III-nitride vertical-cavity surface-emitting laser with a photoelectrochemically etched air-gap aperture

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, J. T., E-mail: jtleona01@gmail.com; Yonkee, B. P.; Cohen, D. A.; Megalini, L.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Lee, S. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); DenBaars, S. P.; Nakamura, S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

    2016-01-18

    We demonstrate a III-nitride nonpolar vertical-cavity surface-emitting laser (VCSEL) with a photoelectrochemically (PEC) etched aperture. The PEC lateral undercut etch is used to selectively remove the multi-quantum well (MQW) region outside the aperture area, defined by an opaque metal mask. This PEC aperture (PECA) creates an air-gap in the passive area of the device, allowing one to achieve efficient electrical confinement within the aperture, while simultaneously achieving a large index contrast between core of the device (the MQW within the aperture) and the lateral cladding of the device (the air-gap formed by the PEC etch), leading to strong lateral confinement. Scanning electron microscopy and focused ion-beam analysis is used to investigate the precision of the PEC etch technique in defining the aperture. The fabricated single mode PECA VCSEL shows a threshold current density of ∼22 kA/cm{sup 2} (25 mA), with a peak output power of ∼180 μW, at an emission wavelength of 417 nm. The near-field emission profile shows a clearly defined single linearly polarized (LP) mode profile (LP{sub 12,1}), which is in contrast to the filamentary lasing that is often observed in III-nitride VCSELs. 2D mode profile simulations, carried out using COMSOL, give insight into the different mode profiles that one would expect to be displayed in such a device. The experimentally observed single mode operation is proposed to be predominantly a result of poor current spreading in the device. This non-uniform current spreading results in a higher injected current at the periphery of the aperture, which favors LP modes with high intensities near the edge of the aperture.

  18. Nonpolar III-nitride vertical-cavity surface-emitting laser with a photoelectrochemically etched air-gap aperture

    Science.gov (United States)

    Leonard, J. T.; Yonkee, B. P.; Cohen, D. A.; Megalini, L.; Lee, S.; Speck, J. S.; DenBaars, S. P.; Nakamura, S.

    2016-01-01

    We demonstrate a III-nitride nonpolar vertical-cavity surface-emitting laser (VCSEL) with a photoelectrochemically (PEC) etched aperture. The PEC lateral undercut etch is used to selectively remove the multi-quantum well (MQW) region outside the aperture area, defined by an opaque metal mask. This PEC aperture (PECA) creates an air-gap in the passive area of the device, allowing one to achieve efficient electrical confinement within the aperture, while simultaneously achieving a large index contrast between core of the device (the MQW within the aperture) and the lateral cladding of the device (the air-gap formed by the PEC etch), leading to strong lateral confinement. Scanning electron microscopy and focused ion-beam analysis is used to investigate the precision of the PEC etch technique in defining the aperture. The fabricated single mode PECA VCSEL shows a threshold current density of ˜22 kA/cm2 (25 mA), with a peak output power of ˜180 μW, at an emission wavelength of 417 nm. The near-field emission profile shows a clearly defined single linearly polarized (LP) mode profile (LP12,1), which is in contrast to the filamentary lasing that is often observed in III-nitride VCSELs. 2D mode profile simulations, carried out using COMSOL, give insight into the different mode profiles that one would expect to be displayed in such a device. The experimentally observed single mode operation is proposed to be predominantly a result of poor current spreading in the device. This non-uniform current spreading results in a higher injected current at the periphery of the aperture, which favors LP modes with high intensities near the edge of the aperture.

  19. Comparison of nonpolar III-nitride vertical-cavity surface-emitting lasers with tunnel junction and ITO intracavity contacts

    Science.gov (United States)

    Leonard, J. T.; Young, E. C.; Yonkee, B. P.; Cohen, D. A.; Shen, C.; Margalith, T.; Ng, T. K.; DenBaars, S. P.; Ooi, B. S.; Speck, J. S.; Nakamura, S.

    2016-02-01

    We report on the lasing of III-nitride nonpolar, violet, vertical-cavity surface-emitting lasers (VCSELs) with IIInitride tunnel-junction (TJ) intracavity contacts and ion implanted apertures (IIAs). The TJ VCSELs are compared to similar VCSELs with tin-doped indium oxide (ITO) intracavity contacts. Prior to analyzing device results, we consider the relative advantages of III-nitride TJs for blue and green emitting VCSELs. The TJs are shown to be most advantageous for violet and UV VCSELs, operating near or above the absorption edge for ITO, as they significantly reduce the total internal loss in the cavity. However, for longer wavelength III-nitride VCSELs, TJs primarily offer the advantage of improved cavity design flexibility, allowing one to make the p-side thicker using a thick n-type III-nitride TJ intracavity contact. This offers improved lateral current spreading and lower loss, compare to using ITO and p-GaN, respectively. These aspects are particularly important for achieving high-power CW VCSELs, making TJs the ideal intracavity contact for any III-nitride VCSEL. A brief overview of III-nitride TJ growth methods is also given, highlighting the molecular-beam epitaxy (MBE) technique used here. Following this overview, we compare 12 μm aperture diameter, violet emitting, TJ and ITO VCSEL experimental results, which demonstrate the significant improvement in differential efficiency and peak power resulting from the reduced loss in the TJ design. Specifically, the TJ VCSEL shows a peak power of ~550 μW with a threshold current density of ~3.5 kA/cm2, while the ITO VCSELs show peak powers of ~80 μW and threshold current densities of ~7 kA/cm2.

  20. Non-polar organic compounds in marine aerosols over the northern South China Sea: Influence of continental outflow.

    Science.gov (United States)

    Zhao, Yan; Zhang, Yingyi; Fu, Pingqing; Ho, Steven Sai Hang; Ho, Kin Fai; Liu, Fobang; Zou, Shichun; Wang, Shan; Lai, Senchao

    2016-06-01

    Filter samples of total suspended particle (TSP) collected during a cruise campaign over the northern South China Sea (SCS) from September to October 2013 were analyzed for non-polar organic compounds (NPOCs) as well as organic carbon (OC), elemental carbon (EC) and water-soluble ions. A total of 115 NPOCs species in groups of n-alkanes, polycyclic aromatic hydrocarbons (PAHs), iso-/antiso-alkanes, hopanes, steranes, methylalkanes, branched alkanes, cycloalkanes, alkenes and phthalates were detected. The characteristics of NPOCs in marine TSP samples were investigated to understand the sources from the Asian continent and other regions. The concentrations of total NPOCs ranged from 19.8 to 288.2 ng/m(3) with an average of 87.9 ng/m(3), which accounted for 0.8-1.7% (average 1.0%) of organic matter (OM). n-Alkanes was the predominant group, accounting for 43.1-79.5%, followed by PAHs (5.5-44.4%) and hopanes (1.6-11.4%). We found that primary combustion (biomass burning/fossil fuel combustion) was the dominant source for the majority of NPOCs (89.1%). Biomass burning in southern/southeastern China via long-range transport was proposed to be a major contributor of NPOCs in marine aerosols over the northern SCS, suggested by the significant correlations between nss-K(+) and NPOCs groups as well as the analysis of air mass back-trajectory and fire spots. For the samples with strong continental influence, the strong enhancement in concentrations of n-alkanes, PAHs, hopanes and steranes were attributed to fossil fuel (coal/petroleum) combustion. In addition, terrestrial plants waxes were another contributor to NPOCs.

  1. Comparison of nonpolar III-nitride vertical-cavity surface-emitting lasers with tunnel junction and ITO intracavity contacts

    KAUST Repository

    Leonard, J. T.

    2016-03-01

    We report on the lasing of III-nitride nonpolar, violet, vertical-cavity surface-emitting lasers (VCSELs) with III-nitride tunnel-junction (TJ) intracavity contacts and ion implanted apertures (IIAs). The TJ VCSELs are compared to similar VCSELs with tin-doped indium oxide (ITO) intracavity contacts. Prior to analyzing device results, we consider the relative advantages of III-nitride TJs for blue and green emitting VCSELs. The TJs are shown to be most advantageous for violet and UV VCSELs, operating near or above the absorption edge for ITO, as they significantly reduce the total internal loss in the cavity. However, for longer wavelength III-nitride VCSELs, TJs primarily offer the advantage of improved cavity design flexibility, allowing one to make the p-side thicker using a thick n-type III-nitride TJ intracavity contact. This offers improved lateral current spreading and lower loss, compare to using ITO and p-GaN, respectively. These aspects are particularly important for achieving high-power CW VCSELs, making TJs the ideal intracavity contact for any III-nitride VCSEL. A brief overview of III-nitride TJ growth methods is also given, highlighting the molecular-beam epitaxy (MBE) technique used here. Following this overview, we compare 12 mu m aperture diameter, violet emitting, TJ and ITO VCSEL experimental results, which demonstrate the significant improvement in differential efficiency and peak power resulting from the reduced loss in the TJ design. Specifically, the TJ VCSEL shows a peak power of similar to 550 mu W with a threshold current density of similar to 3.5 kA/cm(2), while the ITO VCSELs show peak powers of similar to 80 mu W and threshold current densities of similar to 7 kA/cm

  2. Turkish Media Elites

    Directory of Open Access Journals (Sweden)

    D. Ali Arslan

    2008-07-01

    Full Text Available The media is one of the most important institutions in society. It is a reality that media play very substantial role in the production and social distribution of knowledge. In addition to that, mass media provides the greatest communication opportunities to the people. Also, contemporary media provides very distinctive weapons to obtain power, wealth and prestige in the society. If media owners and elites are so powerful, the identification of media elites is of great importance. Hence, this study aims to analyse contemporary Turkish media: A full picture of Turkish media elites in terms of important social, political and demographic indicators will be given in this paper. The managers, editors, influential columnists and reporters of major Turkish media elites are defined as Turkish media elites. Firstly, the paper will focuse on the demographic peculiarities of Turkish media elites. Secondly, the educational background and family structure of Turkish media elites will be examined. Then, social origins and other social characteristics of Contemporary Turkish media elites will be investigated.

  3. AMAMM - All Media Are Mixed Media

    DEFF Research Database (Denmark)

    All Media Are Mixed Media Alle medier er blandingsmedier. Alle kunstarter er kompositte. Alle sanser er sammensatte. Alle medialiteter er miksede og mangfoldige. Alle er AMAMM. Denne påstand står centralt i ord-, billed- og medie-teoretikeren W.J.T. Mitchells forfatterskab. I hosstående bog tager...

  4. Using Social Media to Teach Social Media

    Science.gov (United States)

    Rheingold, Howard

    2008-01-01

    By showing students how to use Web-based channels to inform publics, advocate positions, contest claims, and organize action around issues they care about, participatory media education can influence civic behavior positively throughout their lives. Participatory media literacy is necessarily a hands-on enterprise, requiring active use of digital…

  5. Automating the Media Center.

    Science.gov (United States)

    Holloway, Mary A.

    1988-01-01

    Discusses the need to develop more efficient information retrieval skills by the use of new technology. Lists four stages used in automating the media center. Describes North Carolina's pilot programs. Proposes benefits and looks at the media center's future. (MVL)

  6. Sociale media als leermiddel

    NARCIS (Netherlands)

    Rubens, Wilfred

    2012-01-01

    Rubens, W. (2012, 5 juni). Sociale media als leermiddel. Presentatie over het gebruik van sociale media binnen het onderwijs, verzorgd tijdens een ouderraadbijeenkomst van de Katholieke Scholengemeenschap Etten-Leur, Etten-Leur, Nederland.

  7. MODERN MEDIA EDUCATION MODELS

    Directory of Open Access Journals (Sweden)

    Alexander Fedorov

    2011-03-01

    Full Text Available The author supposed that media education models can be divided into the following groups:- educational-information models (the study of the theory, history, language of media culture, etc., based on the cultural, aesthetic, semiotic, socio-cultural theories of media education;- educational-ethical models (the study of moral, religions, philosophical problems relying on the ethic, religious, ideological, ecological, protectionist theories of media education;- pragmatic models (practical media technology training, based on the uses and gratifications and ‘practical’ theories of media education;- aesthetical models (aimed above all at the development of the artistic taste and enriching the skills of analysis of the best media culture examples. Relies on the aesthetical (art and cultural studies theory; - socio-cultural models (socio-cultural development of a creative personality as to the perception, imagination, visual memory, interpretation analysis, autonomic critical thinking, relying on the cultural studies, semiotic, ethic models of media education.

  8. Media and Crime

    DEFF Research Database (Denmark)

    Agger, Gunhild; Waade, Anne Marit

    2011-01-01

    Recent developments in the relationship between media and crime are analyzed, taking both fiction and journalism in account......Recent developments in the relationship between media and crime are analyzed, taking both fiction and journalism in account...

  9. The social media revolution.

    Science.gov (United States)

    Dubose, Cheryl

    2011-01-01

    The growing popularity and use of social media tools such as Facebook, YouTube, Twitter, blogging, and wikis have led to a social media revolution. Given this widespread influence, it is important for educators, administrators, and technologists to understand the risks of using social media in the classroom and workplace. To investigate popular social media sites and their effect on radiologic technology education and business practices. A comprehensive search of literature was performed to examine social media and its applications in education, health care, and business. Social media use is on the rise, affecting all aspects of mainstream society. Leaders in the radiologic sciences should be familiar with social media and cognizant of its risks. Future studies regarding social media use in the radiologic sciences are necessary to determine its effect on the radiologic science community. ©2011 by the American Society of Radiologic Technologists.

  10. Media and Body Image

    Science.gov (United States)

    ... Media Programs for Girls www.womensmediacenter.com/pages/media-programs-for-girls Glossary Anorexia Nervosa: An eating disorder in which distorted body image leads a person to diet excessively. Body Mass Index (BMI): A number calculated from height and ...

  11. Trends in Media Use

    National Research Council Canada - National Science Library

    Donald F. Roberts; Ulla G. Foehr

    2008-01-01

    .... Donald Roberts and Ulla Foehr examine how both media use and media exposure vary with demographic factors such as age, race and ethnicity, and household socioeconomic status, and with psychosocial...

  12. Trends in media use.

    Science.gov (United States)

    Roberts, Donald F; Foehr, Ulla G

    2008-01-01

    American youth are awash in media. They have television sets in their bedrooms, personal computers in their family rooms, and digital music players and cell phones in their backpacks. They spend more time with media than any single activity other than sleeping, with the average American eight- to eighteen-year-old reporting more than six hours of daily media use. The growing phenomenon of "media multitasking"--using several media concurrently--multiplies that figure to eight and a half hours of media exposure daily. Donald Roberts and Ulla Foehr examine how both media use and media exposure vary with demographic factors such as age, race and ethnicity, and household socioeconomic status, and with psychosocial variables such as academic performance and personal adjustment. They note that media exposure begins early, increases until children begin school, drops off briefly, then climbs again to peak at almost eight hours daily among eleven- and twelve-year-olds. Television and video exposure is particularly high among African American youth. Media exposure is negatively related to indicators of socioeconomic status, but that relationship may be diminishing. Media exposure is positively related to risk-taking behaviors and is negatively related to personal adjustment and school performance. Roberts and Foehr also review evidence pointing to the existence of a digital divide--variations in access to personal computers and allied technologies by socioeconomic status and by race and ethnicity. The authors also examine how the recent emergence of digital media such as personal computers, video game consoles, and portable music players, as well as the media multitasking phenomenon they facilitate, has increased young people's exposure to media messages while leaving media use time largely unchanged. Newer media, they point out, are not displacing older media but are being used in concert with them. The authors note which young people are more or less likely to use several

  13. Children and the Media

    OpenAIRE

    Dennis, Everette E.; Pease, Edward C.

    1996-01-01

    Throughout history the media has primarily been produced by adults, for adults, about adults. Increasingly, children have become a matter of high priority in the modern media society, and as they have, they have also become the subject of much concern. From debates in Congress about the detrimental effects of movies, comic books, and video games over the last century to efforts to court children as media consumers, there is a clear recognition that the media are not now and probably ne...

  14. Managing social media conversations

    OpenAIRE

    2015-01-01

    The purpose of this thesis was to explore how companies can manage (monitor and control) social media conversations. Regardless of the companies’ presence in social media networks, they or their industry are constantly being discussed in social media. Therefore organisations should be present in social media, monitor and participate in conversations, in order to turn them into their benefit. There are software and services available to help in monitoring. Variety of tools and statistic de...

  15. The social media image

    OpenAIRE

    2014-01-01

    How do the organization and presentation of large-scale social media images recondition the process by which visual knowledge, value, and meaning are made in contemporary conditions? Analyzing fundamental elements in the changing syntax of existing visual software ontology—the ways current social media platforms and aggregators organize and categorize social media images—this article relates how visual materials created within social media platforms manifest distinct modes of knowledge produc...

  16. Advertising on social media

    OpenAIRE

    Sumit Goyal

    2013-01-01

    This communication reports the latest trends of advertising on social media. Social media advertising means to gain traffic or attention of online users through social media sites. Today, when a user thinks about buying something, he first comes to the internet, searches for that product, compares its price with other competing brands and takes a decision, which one to buy. In this write-up, author has discussed many aspects concerning advertising through social media, viz., what is social me...

  17. Managing Media Workers

    NARCIS (Netherlands)

    Deuze, M.; Lowe, G.F.; Brown, C.

    2015-01-01

    People are more involved with media than ever but news about media as an industry is less than optimistic. The number of people across the creative industries who are losing jobs illustrates all too well. Media managers seem at a loss in developing survival strategies, and specifically in organizing

  18. Managing Media Workers

    NARCIS (Netherlands)

    M. Deuze

    2015-01-01

    People are more involved with media than ever but news about media as an industry is less than optimistic. The number of people across the creative industries who are losing jobs illustrates all too well. Media managers seem at a loss in developing survival strategies, and specifically in organizing

  19. Mapping digital media: Netherlands

    NARCIS (Netherlands)

    de Waal, M.; Leurdijk, A.; Nordeman, L.; Poell, T.

    2012-01-01

    The Mapping Digital Media project examines the global opportunities and risks created by the transition from traditional to digital media. Covering 60 countries, the project examines how these changes affect the core democratic service that any media system should provide: news about political,

  20. New Media, New Citizens?

    DEFF Research Database (Denmark)

    Ohme, Jakob

    2017-01-01

    The use of news media is regarded as a driver for citizens’ engagement with society and their political participation. But as news media use increasingly shifts to digital platforms, it is crucial to understand the interplay between a changing media environment and recent patterns of political pa...

  1. Youth Media and Agency

    Science.gov (United States)

    Hauge, Chelsey

    2014-01-01

    This article addresses how capacity is conceived of and understood in youth media/civic education programming, and how beliefs about agency, development, relationality and youth manifests in the discourses, programmes, and practices of organizations operating youth media programmes. Through attention to a youth media and development programme in…

  2. Media, Minds, and Masses.

    Science.gov (United States)

    Baggot, James; Vino, Faith

    This booklet describes the language arts course "Media, Minds, and Masses," written for the Dade County, Fla., public schools. Topics for the course include the workings of contemporary radio, television, newspapers, magazines, and movies; the present status and power of media; the history and development of media; and the influences of…

  3. Youth media lifestyles

    NARCIS (Netherlands)

    van Kruistum, Claudia; Leseman, Paul Pm; de Haan, Mariëtte

    2014-01-01

    In this article, the concept of "media lifestyles" is adopted in order to develop a comprehensive approach toward youth engagement in communication media. We explore how 503 Dutch eighth grade students with full access to new technology combine a broad range of media by focusing on their engagement

  4. Modern Media Education Models

    Science.gov (United States)

    Fedorov, Alexander

    2011-01-01

    The author supposed that media education models can be divided into the following groups: (1) educational-information models (the study of the theory, history, language of media culture, etc.), based on the cultural, aesthetic, semiotic, socio-cultural theories of media education; (2) educational-ethical models (the study of moral, religions,…

  5. Children's Media Policy

    Science.gov (United States)

    Jordan, Amy B.

    2008-01-01

    Amy Jordan addresses the need to balance the media industry's potentially important contributions to the healthy development of America's children against the consequences of excessive and age-inappropriate media exposure. Much of the philosophical tension regarding how much say the government should have about media content and delivery stems…

  6. News Media Industry

    Science.gov (United States)

    2007-01-01

    absence of a democratic media law and the lasting power monopoly of the state owned media on the other hand (Myagmar, 2000). First, legal basis of...implementation. The censorship authority was abolished already in 1989, but it was not until the 1998 media law that censorship was prohibited

  7. Teenagers Media Habits.

    Science.gov (United States)

    Campbell, Laurence R.

    This study attempted to determine what media most effectively communicated to teenagers, how the media habits of Florida teenagers compared with those in other states, and how the media habits of journalism students compared with those not in journalism. A total of 430 students from Florida high schools and 457 from high schools in other states…

  8. Mapping digital media: Netherlands

    NARCIS (Netherlands)

    de Waal, M.; Leurdijk, A.; Nordeman, L.; Poell, T.

    2012-01-01

    The Mapping Digital Media project examines the global opportunities and risks created by the transition from traditional to digital media. Covering 60 countries, the project examines how these changes affect the core democratic service that any media system should provide: news about political, econ

  9. ELECTRONS IN NONPOLAR LIQUIDS.

    Energy Technology Data Exchange (ETDEWEB)

    HOLROYD,R.A.

    2002-10-22

    Excess electrons can be introduced into liquids by absorption of high energy radiation, by photoionization, or by photoinjection from metal surfaces. The electron's chemical and physical properties can then be measured, but this requires that the electrons remain free. That is, the liquid must be sufficiently free of electron attaching impurities for these studies. The drift mobility as well as other transport properties of the electron are discussed here as well as electron reactions, free-ion yields and energy levels, Ionization processes typically produce electrons with excess kinetic energy. In liquids during thermalization, where this excess energy is lost to bath molecules, the electrons travel some distance from their geminate positive ions. In general the electrons at this point are still within the coulombic field of their geminate ions and a large fraction of the electrons recombine. However, some electrons escape recombination and the yield that escapes to become free electrons and ions is termed G{sub fi}. Reported values of G{sub fi} for molecular liquids range from 0.05 to 1.1 per 100 eV of energy absorbed. The reasons for this 20-fold range of yields are discussed here.

  10. Prosocial effects of media.

    Science.gov (United States)

    Hogan, Marjorie J

    2012-06-01

    Parents, teachers, health care providers, and other caring adults worry about the harmful influence of media messages and images on children and teens and wonder how to recognize and encourage positive and healthy use of media. For decades, experts have commented on the power of media. Media depictions can lead to negative attitudes and behavior in some young viewers. This article discusses whether prosocial, tolerant, and cooperative attitudes and behavior can be learned and imitated by children and adolescents and whether media can nurture or stimulate creativity or actively promote health and well-being in young consumers.

  11. Oriented Fiber Filter Media

    Directory of Open Access Journals (Sweden)

    R. Bharadwaj

    2008-06-01

    Full Text Available Coalescing filters are widely used throughout industry and improved performance will reduce droplet emissions and operating costs. Experimental observations show orientation of micro fibers in filter media effect the permeability and the separation efficiency of the filter media. In this work two methods are used to align the fibers to alter the filter structure. The results show that axially aligned fiber media improve quality factor on the order of 20% and cutting media on an angle from a thick layered media can improve performance by about 40%. The results also show the improved performance is not monotonically correlated to the average fiber angle of the medium.

  12. Asian Media Productions

    DEFF Research Database (Denmark)

    This work consists of 12 essays on different aspects of Asian media by Japanese, European, and American scholars, many of whom have themselves been involved in the production of media forms. Working in the fields of anthropology, media and cultural studies, and on the basis of hands-on research, ......, they have written a book on the social practices and cultural attitudes of people producing, reading, watching and listening to different kinds of media in Japan, China, Taiwan, Indonesia, Vietnam, Singapore and India.......This work consists of 12 essays on different aspects of Asian media by Japanese, European, and American scholars, many of whom have themselves been involved in the production of media forms. Working in the fields of anthropology, media and cultural studies, and on the basis of hands-on research...

  13. Comprehension of digital media

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju Hwan

    2008-11-15

    This book is divided four parts. The first part describes media and mark on sign and media, what is the sign?, interpretation of sign and semiotics. The second part is for production sign theory and origin of digital revolution such as the problem of origin of digital revolution, homogeneity of producing goods and sign : triple triangle model for production sign theory, triple triangle model for producing goods, triple triangle model of producing sign and triple triangle model of art works. The third parts deals with development of the media and meaning of digital revolution with four changes : invention of letter, appearance of printed media and establishment modernity, appearance electronic media and mess media and appearance of digital media. The last part mentions ontology of world wide web.

  14. The Media Mixer

    DEFF Research Database (Denmark)

    Vestergaard, Vitus; Mortensen, Christian Hviid

    2011-01-01

    throughout the Internet, most notably on web 2.0 sites like YouTube. The Media Museum has embraced the remix paradigm with the development of an interactive media experience centre called the Media Mixer. Here the museum users can produce, deconstruct, reconstruct and finally publish and share digital media......We explore how remixing and content sharing can be used as a means for user participation in a digital museum age. Remix culture is seen as a culture that allows and encourages the production of derivative works; works that are based on already existing works. This cultural practice thrives...... content. The media content is created by the user in the museum's physical environment, but it can be mixed with material from web archives. It is the intention that the users learn about media through participatory and creative processes with media where the borders between producing, playing...

  15. Understanding Social Media Logic

    Directory of Open Access Journals (Sweden)

    José van Dijck

    2013-08-01

    Full Text Available Over the past decade, social media platforms have penetrated deeply into the mech­anics of everyday life, affecting people's informal interactions, as well as institutional structures and professional routines. Far from being neutral platforms for everyone, social media have changed the conditions and rules of social interaction. In this article, we examine the intricate dynamic between social media platforms, mass media, users, and social institutions by calling attention to social media logic—the norms, strategies, mechanisms, and economies—underpin­ning its dynamics. This logic will be considered in light of what has been identified as mass me­dia logic, which has helped spread the media's powerful discourse outside its institutional boundaries. Theorizing social media logic, we identify four grounding principles—programmabil­ity, popularity, connectivity, and datafication—and argue that these principles become increas­ingly entangled with mass media logic. The logic of social media, rooted in these grounding principles and strategies, is gradually invading all areas of public life. Besides print news and broadcasting, it also affects law and order, social activism, politics, and so forth. Therefore, its sustaining logic and widespread dissemination deserve to be scrutinized in detail in order to better understand its impact in various domains. Concentrating on the tactics and strategies at work in social media logic, we reassess the constellation of power relationships in which social practices unfold, raising questions such as: How does social media logic modify or enhance ex­isting mass media logic? And how is this new media logic exported beyond the boundaries of (social or mass media proper? The underlying principles, tactics, and strategies may be relat­ively simple to identify, but it is much harder to map the complex connections between plat­forms that distribute this logic: users that employ them, technologies that

  16. Soft ionization of saturated hydrocarbons, alcohols and nonpolar compounds by negative-ion direct analysis in real-time mass spectrometry.

    Science.gov (United States)

    Cody, Robert B; Dane, A John

    2013-03-01

    Large polarizable n-alkanes (approximately C18 and larger), alcohols, and other nonpolar compounds can be detected as negative ions when sample solutions are injected directly into the sampling orifice of the atmospheric pressure interface of the time-of-flight mass spectrometer with the direct analysis in real time (DART) ion source operating in negative-ion mode. The mass spectra are dominated by peaks corresponding to [M + O2]‾(•). No fragmentation is observed, making this a very soft ionization technique for samples that are otherwise difficult to analyze by DART. Detection limits for cholesterol were determined to be in the low nanogram range.

  17. Soft Ionization of Saturated Hydrocarbons, Alcohols and Nonpolar Compounds by Negative-Ion Direct Analysis in Real-Time Mass Spectrometry

    Science.gov (United States)

    Cody, Robert B.; Dane, A. John

    2013-03-01

    Large polarizable n-alkanes (approximately C18 and larger), alcohols, and other nonpolar compounds can be detected as negative ions when sample solutions are injected directly into the sampling orifice of the atmospheric pressure interface of the time-of-flight mass spectrometer with the direct analysis in real time (DART) ion source operating in negative-ion mode. The mass spectra are dominated by peaks corresponding to [M + O2]‾•. No fragmentation is observed, making this a very soft ionization technique for samples that are otherwise difficult to analyze by DART. Detection limits for cholesterol were determined to be in the low nanogram range.

  18. Media relations after the introduction of social media

    OpenAIRE

    Mesila, Helin

    2010-01-01

    In the light of the popularity of social media on one hand, and the contradictive relationships between journalists and public relations practitioners on the other hand, the thesis studies media relations after the introduction of social media. The study focuses on media relations in Estonian public relations scenery. The research answers to the questions: - What are media relations today? - What are the functions of social media and media relations in organizational communication? ...

  19. The Media Mixer

    DEFF Research Database (Denmark)

    Vestergaard, Vitus; Mortensen, Christian Hviid

    In recent years many museums have experimented with different approaches to involving users through digital media. We explore how remixing and content sharing can be used as a means for user participation. Remix culture is seen as a culture that allows and encourages the production of derivative...... the museum users can produce, deconstruct, reconstruct and finally publish and share digital media content. The media content is created by the user in the museums physical environment, but it can be mixed with material from local or global archives. In that way the gap between the analogue and the digital...... works; works that are based on already existing works. This cultural practice thrives throughout the Internet, most notably on web2.0 sites like YouTube. The Media Museum has embraced the remix paradigm with the development of an interactive media experience centre called the Media Mixer. Here...

  20. Organizational Communication and Media

    DEFF Research Database (Denmark)

    Tække, Jesper

    of Niklas Luhmann (Tække & Paulsen 2008, Tække 2008a) with analysis of how organizations communicate in and about media. Using systems theory and form theory, it puts forward a theoretical framework and a strategy for analysing organisational communication in and about media. The medium aspect is inspired......  The paper reflects an interest in the relation between organizational communication and media. It tries to answer the question, how we can observe the relationship between organizational communication and media. It is a work-in-progress which tries to combine organizational studies inspired...... is a possible framework to draw the two disciplines together in, because it is a theory about the relation between the social and the media it is based on. First the paper sum up the Luhmann inspired theory about organizations, fleshing out how organizations are thought to communicate in and about media and how...

  1. Pervasive media violence.

    Science.gov (United States)

    Schooler, C; Flora, J A

    1996-01-01

    In this review, we focus our discussion on studies examining effects on children and young adults. We believe that the current epidemic of youth violence in the United States justifies a focus on this vulnerable segment of society. We consider media effects on individual children's behaviors, such as imitating aggressive acts. In addition, we examine how the media influence young people's perceptions of norms regarding interpersonal relationships. Next, we assess mass media effects on societal beliefs, or what children and adolescents think the "real world" is like. We suggest these media influences are cumulative and mutually reinforcing, and discuss the implications of repeated exposure to prominent and prevalent violent media messages. Finally, we catalog multiple intervention possibilities ranging from education to regulation. From a public health perspective, therefore, we evaluate the effects that pervasive media messages depicting violence have on young people and present multiple strategies to promote more healthful outcomes.

  2. The Media Mixer

    DEFF Research Database (Denmark)

    Vestergaard, Vitus; Mortensen, Christian Hviid

    In recent years many museums have experimented with different approaches to involving users through digital media. We explore how remixing and content sharing can be used as a means for user participation. Remix culture is seen as a culture that allows and encourages the production of derivative...... the museum users can produce, deconstruct, reconstruct and finally publish and share digital media content. The media content is created by the user in the museums physical environment, but it can be mixed with material from local or global archives. In that way the gap between the analogue and the digital...... works; works that are based on already existing works. This cultural practice thrives throughout the Internet, most notably on web2.0 sites like YouTube. The Media Museum has embraced the remix paradigm with the development of an interactive media experience centre called the Media Mixer. Here...

  3. Social media visibility

    DEFF Research Database (Denmark)

    Uldam, Julie

    2017-01-01

    of activists remains under-researched. This article examines BP’s surveillance of activists who criticise the company’s corporate social responsibility (CSR) programme as ‘greenwashing’. In this way, it goes beyond corporations’ uses of big data and instead explores how they monitor and discuss strategies......As activists move from alternative media platforms to commercial social media platforms, they face increasing challenges in protecting their online security and privacy. While government surveillance of activists is well-documented in scholarly research and the media, corporate surveillance...... for responding to the activities of individual activists in social media. It shows that while social media afford an unprecedented level of visibility for activists, it comes with the risk of being monitored by corporations. Theoretically, it draws on conceptions of visibility in social sciences and media...

  4. Marketing w social media

    OpenAIRE

    Dorenda-Zaborowicz, Marta

    2012-01-01

    The precise definition of social media marketing is hard to establish, but it can be said that it is the methodical use of new technologies and social networks to achieve specific goals for a company. In simple terms social marketing means advertising a company through many different media, like viral videos and blogs, to achieve its maximum exposure. Nevertheless, social media marketing may also refer to advertising certain social issues, such as NGOs’ or civic actions’ promotion. Precyzy...

  5. What is Media Innovation?

    OpenAIRE

    2014-01-01

    In order to understand and explain current developments in the media landscape, using the lens of innovation and innovation theory adds value to media research. This chapter gives a theoretical introduction to the concept of innovation. It argues that media innovations may be related to product innovation, process innovation, position innovation, paradigmatic innovation and social innovation, and that innovation may involve different degrees of novelty. The chapter also highlights key influen...

  6. Social Media: Human Life

    Directory of Open Access Journals (Sweden)

    Nick Couldry

    2015-04-01

    Full Text Available This article explores the idea that research into media communications and information has recently undergone a normative turn as more and more writers reflect on the ever deeper embedding of our lives in media, and the possible costs that this entails. Possible ways forward for deepening and addressing this normative turn are explored, based on the particular contribution to media and communications research of social theory.

  7. Mode Coupling between the Nonpolar K3 and Polar Γ2-Phonons as the Ferroelectricity Origin of Multiferroic h-LuMnO3

    Science.gov (United States)

    Song, Seungwoo; Heo, Seungyang; Jang, Hyun Myung

    2014-03-01

    LuMnO3 is expected to show the highest stability towards the hexagonal phase among 15 different lanthanide-based manganites. Currently, the most puzzling problem associated with the hexagonal LuMnO3 (h-LMO) is the observed large temperature-gap between the structural phase transition to the polar P63cm phase at ~ 1290 K and the emergence of the spontaneous polarization at a substantially reduced temperature, ~ 750 K. This anomalous temperature-gap has also been observed in h-YMnO3. To resolve this puzzling issue, we have carried out density-functional theory calculations and found that the structural phase transition to the polar P63 cm phase from the nonpolar P63/mmc phase is mediated by the freezing-in of the zone-boundary K3 phonon in h-LMO. However, the spontaneous ferroelectric polarization does not appear until the amplitude of K3 phonon becomes a certain critical value above which the coupling of the polar Γ2-mode with the nonpolar K3 mode is practically turned on. This mode-coupling-induced polarization, thus, elucidates the above puzzle.

  8. Growth of non-polar (11-20 InGaN quantum dots by metal organic vapour phase epitaxy using a two temperature method

    Directory of Open Access Journals (Sweden)

    J. T. Griffiths

    2014-12-01

    Full Text Available Non-polar (11-20 InGaN quantum dots (QDs were grown by metal organic vapour phase epitaxy. An InGaN epilayer was grown and subjected to a temperature ramp in a nitrogen and ammonia environment before the growth of the GaN capping layer. Uncapped structures with and without the temperature ramp were grown for reference and imaged by atomic force microscopy. Micro-photoluminescence studies reveal the presence of resolution limited peaks with a linewidth of less than ∼500 μeV at 4.2 K. This linewidth is significantly narrower than that of non-polar InGaN quantum dots grown by alternate methods and may be indicative of reduced spectral diffusion. Time resolved photoluminescence studies reveal a mono-exponential exciton decay with a lifetime of 533 ps at 2.70 eV. The excitonic lifetime is more than an order of magnitude shorter than that for previously studied polar quantum dots and suggests the suppression of the internal electric field. Cathodoluminescence studies show the spatial distribution of the quantum dots and resolution limited spectral peaks at 18 K.

  9. Fatty acid profiles of polar and non-polar lipids of Pleurotus ostreatus and P. cornucopiae var. 'citrino-pileatus' grown at different temperatures.

    Science.gov (United States)

    Pedneault, Karine; Angers, Paul; Avis, Tyler J; Gosselin, André; Tweddell, Russell J

    2007-10-01

    The application of fatty acid (FA) composition data has now extended to studies of physiology, chemotaxonomy, and intrageneric differentiation, as well as to studies of human nutrition. Environmental factors such as nutritional components, oxygen, and temperature are known to affect lipid content and composition in living organisms, including fungi. In the present study, the polar and non-polar lipid content of Pleurotus ostreatus and P. cornucopiae var. citrino-pileatus fruiting bodies produced at temperatures ranging from 12-27 degrees C and from 17-27 degrees C, respectively, were analysed to evaluate the effect of temperature on lipid composition in these mushrooms. Results showed that lowering the growth temperature below 17 degrees C generally provided an expected increase in FA unsaturation in polar and non-polar lipids of P. ostreatus. Although raising the temperature above 17 degrees C did not show any clear-cut tendency in FA unsaturation, it did reveal that growth temperature had a differential effect on the FA profiles in fruiting bodies of P. ostreatus and P. cornucopiae. This study suggests that care should be taken when using FA content and unsaturation data for physiological, chemotaxonomic, and intrageneric differentiation studies, and that it may be possible to manipulate lipid unsaturation in Pleurotus spp. through modified growth temperatures.

  10. Characterization of electron-beam recorded microdomain patterns on the nonpolar surface of LiNbO{sub 3} crystal by nondestructive methods

    Energy Technology Data Exchange (ETDEWEB)

    Kokhanchik, L. S. [Institute of Microelectronics Technology and High Purity Materials of the Russian Academy of Sciences, 142432 Chernogolovka, Moscow District (Russian Federation); Gainutdinov, R. V.; Volk, T. R., E-mail: volk@ns.crys.ras.ru [Institute of Crystallography of the Russian Academy of Sciences, 119333 Moscow (Russian Federation); Mishina, E. D.; Lavrov, S. D. [Moscow State Institute of Radio Engineering, Electronics and Automation, 119454 Moscow (Russian Federation)

    2014-10-06

    We report on characterization of the electron-beam fabricated planar domain gratings on the nonpolar (Y-) surface of LiNbO{sub 3} crystals performed with the use of AFM and confocal second harmonic generation (SHG) microscopy. The dependence of domain formation on the irradiation conditions was investigated. The relation of domain thicknesses to the electron penetration depth is experimentally proved. In particular, the possibility of controlling the thickness of planar domains by varying acceleration electron-beam voltages is demonstrated. The observed specificity of SHG is analyzed in the framework of the Kleinman-Boyd theory [G. D. Boyd and D. A. Kleinman, J. Appl. Phys. 39, 3597 (1968)] and Uesu approach [Kaneshiro et al., J. Appl. Phys. 104, 054112 (2008); Kaneshiro et al., J. Opt. Soc. Am. B 27, 888 (2010)] extended in our case to reflection geometry. The calculations performed predict the dependence of SHG conversion efficiency η on the domain thickness, which is in a qualitative agreement with the experiment. It is shown that planar domains on top of the nonpolar surface always enhance the value of η as compared with the bare surface.

  11. Characterization of electron-beam recorded microdomain patterns on the nonpolar surface of LiNbO3 crystal by nondestructive methods

    Science.gov (United States)

    Kokhanchik, L. S.; Gainutdinov, R. V.; Mishina, E. D.; Lavrov, S. D.; Volk, T. R.

    2014-10-01

    We report on characterization of the electron-beam fabricated planar domain gratings on the nonpolar (Y-) surface of LiNbO3 crystals performed with the use of AFM and confocal second harmonic generation (SHG) microscopy. The dependence of domain formation on the irradiation conditions was investigated. The relation of domain thicknesses to the electron penetration depth is experimentally proved. In particular, the possibility of controlling the thickness of planar domains by varying acceleration electron-beam voltages is demonstrated. The observed specificity of SHG is analyzed in the framework of the Kleinman-Boyd theory [G. D. Boyd and D. A. Kleinman, J. Appl. Phys. 39, 3597 (1968)] and Uesu approach [Kaneshiro et al., J. Appl. Phys. 104, 054112 (2008); Kaneshiro et al., J. Opt. Soc. Am. B 27, 888 (2010)] extended in our case to reflection geometry. The calculations performed predict the dependence of SHG conversion efficiency η on the domain thickness, which is in a qualitative agreement with the experiment. It is shown that planar domains on top of the nonpolar surface always enhance the value of η as compared with the bare surface.

  12. THE INFLUENCE OF POLAR AND NON-POLAR EMOLLIENTS ON THE STRUCTURE AND SKIN MOISTURIZING POTENTIAL OF THE EMULSIONS STABILIZED BY MIXED EMULSIFIER

    Directory of Open Access Journals (Sweden)

    Dragana Stojiljković

    2016-06-01

    Full Text Available The appropriate moisture content in the stratum corneum, as a superficial layer of the epidermis, provides softness and flexibility of the skin in different environmental conditions, and maintaining of skin humidity is very important in dermatology and dermocosmetology. In this paper, we investigated the skin moisturizing potential after a single application and structure of the emulsion of o/w type, stabilized by mixed emulsifier glycerylmonostearate self-emulsifying (GMSse, which contained polar emollients (PEG-7 glicerylcocoate and myristyl myristate and non-polar emollient (liquid paraffin, in a concentration of 10% (emulsions E1-E3, respectively. The emulsion structure was investigated by polarization microscopy, and the presence of different anisotropic structure was observed. The moisturizing potential after a single application and skin pH were investigated by skin bioengineering. Emulsions with polar emollients (E1 and E2 showed a statistically significant increase in skin moisture content after 30 minutes; 300 min after applications it did not exist; emulsion with a non-polar emollient (E3 showed significant moisturizing potential after 30 min and after 300 min probably as a consequence of occlusion. Nature and polarity of emollients affected the structure and properties of emulsions stabilized by anisotropic structures, and also the moisturizing level and pH of the skin immediately after their application.

  13. Current mapping of nonpolar a-plane and polar c-plane GaN films by conductive atomic force microscopy

    Science.gov (United States)

    Xu, Shengrui; Jiang, Teng; Lin, Zhiyu; Zhao, Ying; Yang, Linan; Zhang, Jincheng; Li, Peixian; Hao, Yue

    2016-10-01

    Nonpolar (11-20) a-plane GaN and polar (0001) c-plane GaN films have been grown by metal organic chemical vapor deposition on r-plane (1-102) and c-plane (0001) sapphire substrates, respectively. Conductive atomic force microscopy (C-AFM) has been used to investigate the local conductivity of the films. C-AFM shows enhanced current conduction within the etch pits of c-plane GaN and triangular pits of a-plane GaN. The results indicate that the off-axis planes are more electrically active than c-plane and a-plane. Surprisingly, the C-AFM values in triangular pit of the a-plane GaN are much smaller than that in etch pits of the c-plane GaN. The dislocations type related current leakage mechanism is revealed for polar c-plane and nonpolar a-plane GaN films.

  14. Atmospheric pressure chemical ionization studies of non-polar isomeric hydrocarbons using ion mobility spectrometry and mass spectrometry with different ionization techniques

    Science.gov (United States)

    Borsdorf, H.; Nazarov, E. G.; Eiceman, G. A.

    2002-01-01

    The ionization pathways were determined for sets of isomeric non-polar hydrocarbons (structural isomers, cis/trans isomers) using ion mobility spectrometry and mass spectrometry with different techniques of atmospheric pressure chemical ionization to assess the influence of structural features on ion formation. Depending on the structural features, different ions were observed using mass spectrometry. Unsaturated hydrocarbons formed mostly [M - 1]+ and [(M - 1)2H]+ ions while mainly [M - 3]+ and [(M - 3)H2O]+ ions were found for saturated cis/trans isomers using photoionization and 63Ni ionization. These ionization methods and corona discharge ionization were used for ion mobility measurements of these compounds. Different ions were detected for compounds with different structural features. 63Ni ionization and photoionization provide comparable ions for every set of isomers. The product ions formed can be clearly attributed to the structures identified. However, differences in relative abundance of product ions were found. Although corona discharge ionization permits the most sensitive detection of non-polar hydrocarbons, the spectra detected are complex and differ from those obtained with 63Ni ionization and photoionization. c. 2002 American Society for Mass Spectrometry.

  15. The digital media handbook

    CERN Document Server

    Dewdney, Andrew

    2013-01-01

    The new edition of The Digital Media Handbook presents an essential guide to the historical and theoretical development of digital media, emphasising cultural continuity alongside technological change, and highlighting the emergence of new forms of communication in contemporary networked culture.Andrew Dewdney and Peter Ride present detailed critical commentary and descriptive historical accounts, as well as a series of interviews from a range of digital media practitioners, including producers, developers, curators and artists.The Digital Media Handbook highlights key concerns of today's prac

  16. Antennas in inhomogeneous media

    CERN Document Server

    Galejs, Janis; Fock, V A; Wait, J R

    2013-01-01

    Antennas in Inhomogeneous Media details the methods of analyzing antennas in such inhomogeneous media. The title covers the complex geometrical configurations along with its variational formulations. The coverage of the text includes various conditions the antennas are subjected to, such as antennas in the interface between two media; antennas in compressible isotropic plasma; and linear antennas in a magnetoionic medium. The selection also covers insulated loops in lossy media; slot antennas with a stratified dielectric or isotropic plasma layers; and cavity-backed slot antennas. The book wil

  17. Overview: new media.

    Science.gov (United States)

    O'Keeffe, Gwenn Schurgin

    2012-06-01

    Pediatricians care for children's growth and development from the time they are born until they become adults. In addition, pediatricians must be vigilant for external influences. Technology influences children of all ages. Seventy-five percent of teenagers own cell phones, with 25% using them for social media. Technology can lead to an increase in skills and social benefits but there is also the potential for harm such as sexting, cyberbullying, privacy issues, and Internet addiction, all of which can affect health. Pediatricians must become well versed in the new media to provide media-oriented anticipatory guidance and advice on media-related issues.

  18. Media multitasking in adolescence.

    Science.gov (United States)

    Cain, Matthew S; Leonard, Julia A; Gabrieli, John D E; Finn, Amy S

    2016-12-01

    Media use has been on the rise in adolescents overall, and in particular, the amount of media multitasking-multiple media consumed simultaneously, such as having a text message conversation while watching TV-has been increasing. In adults, heavy media multitasking has been linked with poorer performance on a number of laboratory measures of cognition, but no relationship has yet been established between media-multitasking behavior and real-world outcomes. Examining individual differences across a group of adolescents, we found that more frequent media multitasking in daily life was associated with poorer performance on statewide standardized achievement tests of math and English in the classroom, poorer performance on behavioral measures of executive function (working memory capacity) in the laboratory, and traits of greater impulsivity and lesser growth mindset. Greater media multitasking had a relatively circumscribed set of associations, and was not related to behavioral measures of cognitive processing speed, implicit learning, or manual dexterity, or to traits of grit and conscientiousness. Thus, individual differences in adolescent media multitasking were related to specific differences in executive function and in performance on real-world academic achievement measures: More media multitasking was associated with poorer executive function ability, worse academic achievement, and a reduced growth mindset.

  19. Sosiaalinen media ja markkinointi

    OpenAIRE

    Salmela, Mikko

    2014-01-01

    Opinnäytetyön toimeksiantajana oli mainostoimisto Media M1. Media M1 on Jyväskyläläinen mainostoimisto, jossa suunnitellaan ja toteutetaan markkinointia printti- ja digimedioihin. Opinnäytetyön aiheeksi valittiin sosiaalinen media ja sen hyödyntäminen markkinoinnissa. Nykyaikana yhä useampi yritys on alkanut siirtyä markkinoimaan myös sosiaalisessa mediassa. Tämän takia Media M1 halusi saada ajankohtaisen selvityksen palveluiden tilanteesta. Opinnäytetyössä selvitettiin sosiaalisen median...

  20. Media Monopoly in Brazil.

    Science.gov (United States)

    Amaral, Roberto; Guimaraes, Cesar

    1994-01-01

    Documents the process of broadcasting media development in Brazil, the failure of new technologies to produce democratization, and the barriers to democratization erected by monopolization and "metastasis." (SR)

  1. Experimental and theoretical study of polarized photoluminescence caused by anisotropic strain relaxation in nonpolar a-plane textured ZnO grown by a low-pressure chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Chih-Ming [Department of Electronic Engineering, Ming Chuan University, Taoyuan 333, Taiwan (China); Huang, Yu-En; Feng, Shih-Wei, E-mail: swfeng@nuk.edu.tw [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Kou, Kuang-Yang [Department of Traffic Science, Central Police University, Taoyuan 333, Taiwan (China); Chen, Chien-Hsun [Green Energy and Environment Research Labs, Industrial Technology Research Institute, Hsinchu 310, Taiwan (China); Tu, Li-Wei [Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China)

    2015-07-13

    Anisotropic strain relaxation and the resulting degree of polarization of photoluminescence (PL) in nonpolar a-plane textured ZnO are experimentally and theoretically studied. A thicker nonpolar a-plane textured ZnO film enhances the anisotropic in-plane strain relaxation, resulting in a larger degree of polarization of PL and better sample quality. Anisotropic in-plane strains, sample quality, and degree of polarization of PL in nonpolar a-plane ZnO are consequences of the degree of anisotropic in-plane strain relaxation. By the k·p perturbation approach, simulation results of the variation of the degree of polarization for the electronic transition upon anisotropic in-plane strain relaxation agree with experimental results.

  2. Some Media Relations Success Stories.

    Science.gov (United States)

    Sperbeck, John M.

    1997-01-01

    A panel of 29 extension faculty/staff members who work well with the media were interviewed to identify ways to improve their media relations. Reasons for working with the media, ways to develop relationships with media representatives, and suggestions for creating a more favorable climate for media relations in universities were noted. (JOW)

  3. Reconceptualizing (new media literacy

    Directory of Open Access Journals (Sweden)

    Petra Aczel

    2014-02-01

    Full Text Available This paper aims to introduce a theoretical-critical approach which shall revisit elements and cast light upon subsets of (new media literacy. It endeavours to draw community, spatial, procedural and aural literacy (auralacy into consideration, relating them to the complex of media literacy, striving to provide invigorating insights into its conceptual foundations and integrated perspectives for its pedagogy.

  4. Teaching Media Literacy

    Science.gov (United States)

    David, Jane L.

    2009-01-01

    Media literacy is making a comeback, spurred by students' access to unlimited information on the Internet. Can schools provide the skills students need to become media literate in a digital world? Researchers find that reading for understanding online requires the same skills as offline reading, including using prior knowledge and making…

  5. Loneliness and Media Gratifications.

    Science.gov (United States)

    Canary, Daniel J.; Spitzberg, Brian H.

    1993-01-01

    Assesses the nature of the relationship between experienced loneliness and media gratifications. Finds that chronically lonely college students rely less on media for escape than do others and that they reported the least motivation for watching their favorite soap opera. (SR)

  6. Building Social Media Connections

    Science.gov (United States)

    Ferriter, William N.; Ramsden, Jason T.; Sheninger, Eric C.

    2012-01-01

    Incorporating social media tools into your professional practices does not have to be intimidating as long as you are willing to tackle five action steps. It is far easier to articulate the strengths--and to imagine the possibilities--of social media spaces as tools for communication and professional development when you are actively using those…

  7. Corporate Media Governance

    NARCIS (Netherlands)

    Kempen, Petrus Cornelis

    2011-01-01

    The media can make or break a reputation. This being said, it seems to be essential for companies, governments and institutions to pay specific attention to corporate media management in their daily operations. However, this thesis shows that they often neglect to pay adequate attention to corporate

  8. Social Media and Teaching

    DEFF Research Database (Denmark)

    Tække, Jesper; Paulsen, Michael

    New research in the Danish upper secondary schools shows that social media like Facebook is the number one attention diverts from the interaction about educational subjects in the classroom. At the same time international research shows that there is a great potential in using social media in the...

  9. Eosinofiele otitis media

    NARCIS (Netherlands)

    de Jong, Monique A M; Smithuis, L O M J Otto; Stokroos, Robert J

    2014-01-01

    BACKGROUND: Eosinophilic otitis media (EOM) is a rare middle ear disease that may closely resemble therapy-resistant otitis media with effusion (OME). The diagnosis is made if eosinophil-rich fluid is present with two or more of the following minor criteria: (a) history of nasal polyps or, (b) bronc

  10. Corporate Media Governance

    NARCIS (Netherlands)

    Kempen, Petrus Cornelis

    2011-01-01

    The media can make or break a reputation. This being said, it seems to be essential for companies, governments and institutions to pay specific attention to corporate media management in their daily operations. However, this thesis shows that they often neglect to pay adequate attention to corporate

  11. Social Media. Research Brief

    Science.gov (United States)

    Williamson, Ronald

    2010-01-01

    The growing use of social media by students and adults is impacting schools. A recent Pew study found that 73% of teens use social-networking sites to connect with others. Social media includes blogs, wikis, and podcasts as well as sites such as MySpace, Facebook, and Linkedin. While such sites promote connection with others, their use has created…

  12. Understanding social media logic

    NARCIS (Netherlands)

    van Dijck, J.; Poell, T.

    2013-01-01

    Over the past decade, social media platforms have penetrated deeply into the mech­anics of everyday life, affecting people's informal interactions, as well as institutional structures and professional routines. Far from being neutral platforms for everyone, social media have changed the conditions a

  13. Media Specialists Evaluation System.

    Science.gov (United States)

    Reese, Carol; Marsen, Louise

    Intended to provide a comprehensive system for the evaluation of a media specialist's total job performance, this three-part evaluation form is based on the St. Louis Community College's Faculty Evaluation System: Instructional Resources Faculty, August 1981. Designed for peer evaluation of media specialists, the first form includes a rating scale…

  14. Building Social Media Connections

    Science.gov (United States)

    Ferriter, William N.; Ramsden, Jason T.; Sheninger, Eric C.

    2012-01-01

    Incorporating social media tools into your professional practices does not have to be intimidating as long as you are willing to tackle five action steps. It is far easier to articulate the strengths--and to imagine the possibilities--of social media spaces as tools for communication and professional development when you are actively using those…

  15. Advertising Pressures on Media.

    Science.gov (United States)

    Hammitt, Harry

    The majority of the media in the United States is funded through revenues derived from the sale of advertising space. The problem that arises from this situation is fundamentally an economic one: if advertisers are paying the bills for the media, how much control over content should they have? This report offers a review of instances in which…

  16. Understanding social media logic

    NARCIS (Netherlands)

    van Dijck, J.; Poell, T.

    2013-01-01

    Over the past decade, social media platforms have penetrated deeply into the mech­anics of everyday life, affecting people's informal interactions, as well as institutional structures and professional routines. Far from being neutral platforms for everyone, social media have changed the conditions

  17. Digital Media and Learning

    Science.gov (United States)

    John D. and Catherine T. MacArthur Foundation, 2012

    2012-01-01

    MacArthur launched the digital media and learning initiative in 2006 to explore how digital media are changing the way young people learn, socialize, communicate, and play. Since 2006, the Foundation has awarded grants totaling more than $100 million for research, development of innovative new technologies, new learning environments for youth,…

  18. Japanese Media in English.

    Science.gov (United States)

    Tanaka, Sachiko Oda

    1995-01-01

    Describes the use of English in the media in Japan, focusing on the role and history of English-language newspapers, radio, and television programs, as well as the proliferation of English-language films shown in Japanese cinemas. Discusses the implications of English in the Japanese media. (20 references) (MDM)

  19. Media Sociography on Weblogs

    DEFF Research Database (Denmark)

    Tække, Jesper

    to the media it is based on. Theoretically seen it is inspired of two theoretical paradigms the Sociological Systems Theory of Niklas Luhmann and the Media Theory (also called the Toronto school). Empirically the paper primary draws on the literature about weblogs, which could be framed as CMC......Weblogs are not only one of the newest technical media for communication, but also one of the most difficult to understand. Are weblogs a kind of mass medium, a personal medium like an online diary, or a medium that gives space for communities to grow? Or are weblogs a medium that enable all...... these possibilities depended on the actual use? This paper throws some light on what weblogs are by using the methodology of Media Sociography (Tække 2003, 2004a, 2004b and 2004c). Media Sociography is a strategy for analysing mediated social systems or in other words a strategy for describing the social in relation...

  20. Subsidizing Media Innovation

    DEFF Research Database (Denmark)

    Kammer, Aske; Hobel, Emil

    2016-01-01

    and economically sustainable activity, the institutionalization of financial support for media innovation constitute one way for policy makers to bring (parts of) the journalistic environment up-to-date with the digital age, thereby improving the conditions for an informed citizenry in the future (Kammer...... analytical approaches (inspired by the methodology of "qualitative media analysis", cf. Altheide & Schneider, 2013), the paper analyzes to what extent the administration reflects a support of the welfare framework the subsidy scheme exists within. It asks (1) which types of news-media innovation gets......When the Danish Parliament revised the media-subsidy framework in 2013/2014, one of the new initiatives was the introduction of a pool of funding earmarked to establishing and developing new news media – the so-called “innovation fund”. So, as the news industry struggles to keep journalism a viable...

  1. Media Appropriation and Explicitation

    Directory of Open Access Journals (Sweden)

    Tomas Laurenzo

    2016-12-01

    Full Text Available This paper presents a novel characterization of new media art together with an exploration of some key aspects of its practice: I propose that new media art’s defining characteristics are media appropriation and explicitation. With media appropriation I refer to the dialectal inscription into the art practice of the knowledge that allows for some particular technological production. I also propose that new media art’s language is constructed in part via the explicitation of certain aspects of more ‘traditional’ art, and that this explicitation allows for a construction of a new vocabulary. Examples of this are the explicitation of randomness, interaction, programming, or of the role that tools and instruments play, among others.

  2. Social Media Policies

    DEFF Research Database (Denmark)

    Stohl, Cynthia; Etter, Michael; Banghart, Scott

    2017-01-01

    Three global developments situate the context of this investigation: the increasing use of social media by organizations and their employees, the burgeoning presence of social media policies, and the heightened focus on corporate social responsibility (CSR). In this study the intersection...... of these trends is examined through a content analysis of 112 publicly available social media policies from the largest corporations in the world. The extent to which social media policies facilitate and/or constrain the communicative sensibilities and values associated with contemporary notions of CSR...... negotiation and participation in the social responsibilities of corporations. Moreover, policies generally enact organizational communication practices that are contrary to international CSR guidelines (e.g., the UN Global Compact and other international agreements). Findings suggest that social media...

  3. Social Media in Organizations

    DEFF Research Database (Denmark)

    Razmerita, Liana; Kirchner, Kathrin; Nabeth, Thierry

    2014-01-01

    By using social media, many companies try to exploit new forms of interaction, collaboration, and knowledge sharing through leveraging the social, collaborative dimension of social software. The traditional collective knowledge management model based on a top-down approach is now opening up new...... avenues for a bottom-up approach incorporating a more personal knowledge management dimension, which could be synergized into collective knowledge using the social-collaborative dimension of social media. This article addresses the following questions: (1) How can social media support the management...... of personal and collective knowledge using a synergetic approach? (2) Do the personal and collective dimensions compete with each other or can they reinforce each other in a more effective manner using social media? Our findings indicate that social media supports both the personal and collective dimensions...

  4. Social Media Reputation

    DEFF Research Database (Denmark)

    Etter, Michael; Colleoni, Elanor; Ravasi, Davide

    directly to corporate performance and actions. Secondly, prominent reputation measurements couple stakeholders´ believes to reputation drivers through the use of predefined scales and items. We argue that with the rise of social media a company´s reputation has increasingly become autonomous from corporate...... actions, which demands a greater decoupling of stakeholders´ perceptions from corporate signals or actions in corporate reputation research. We develop the concept of social media reputation as the overall evaluation of a company presented in social media and present a new approach of measuring reputation...... based on social media data that accounts for the autonomy of stakeholder´s perception of a firm. We compare and contrast this novel social media reputation measure (SMRM) with traditional reputation measurements and find that SMRM is a valuable measurement to capture the autonomy of the stakeholders...

  5. Creative Digital Media Practices

    DEFF Research Database (Denmark)

    Frølunde, Lisbeth

    The presentation reviews the interplay of dialogic (Bakhtin, 1981) and multimodal theories on media production practices, with attention to visual communication (Kress and van Leeuwen, 2001, 2006). This theoretical approach aids in reflecting on digital media practices as novel (new) sign systems...... on collaboration (Benkler, 2006). The shift toward visual modes and digital media practices pose many pedagogical challenges for academics. I want to raise questions on how to teach “dialogically” with and through creative, digital media practices based on my plans for a course in Fall, 2011, where students...... develop a collaborative digital storytelling showcase for their own digital stories about Roskilde University. This course is intended to bring up reflections on the wider phenomenon of contemporary media practices, such as: YouTube, DIY (do-it-yourself) filmmaking or homemade, garage cinema (Jenkins...

  6. Social Justice and Media. Media Corner.

    Science.gov (United States)

    Braun, Joseph A., III, Ed.

    1994-01-01

    Contends that the end of slavery, women's suffrage, and the civil rights movement were watershed events of social justice in U.S. history. Provides reviews of two media-based sets of instructional materials that can help students understand the struggle by disenfranchised groups to become full participants in society. (CFR)

  7. Social media modeling and computing

    CERN Document Server

    Hoi, Steven CH; Boll, Susanne; Xu, Dong; Jin, Rong; King, Irwin

    2011-01-01

    Presents contributions from an international selection of preeminent experts in the field Discusses topics on social-media content analysis, and examines social-media system design and analysis Describes emerging applications of social media

  8. Bullying and social media affordances

    OpenAIRE

    Brailas, Alexios

    2016-01-01

    What constitutes a good and sustainabledigital living?Social media literacyCan we talk about social media intelligence?Can we talk about digital intelligence?How bullying is complicated by special social media affordances?

  9. Double relaxation phenomena of associated binary polar liquid mixture in non-polar solvent under high frequency electric field

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, S. [Department of Electronics and Instrumentation Engg (India)], E-mail: swapansit@yahoo.co.in; Sit, S.K. [Department of Physics, Dr. Meghnad Saha Institute of Technology, Debhog, Haldia, Purba Medinipore, West Bengal 721657 (India)

    2009-06-25

    Double relaxation times {tau}{sub 2} and {tau}{sub 1} due to whole molecular rotation and the flexible parts of the binary polar liquid mixture (jk) 3-bromoaniline and 1-propanol dissolved in non-polar solvent (i) benzene were estimated in terms of measured real {chi}{sup '}{sub ijk}, imaginary {chi}{sup ''}{sub ijk} parts of complex high frequency orientational susceptibility {chi}{sub ijk}{sup *} and {chi}{sub 0ijk} which is real at 20, 30, 40 and 47 deg. C experimental temperatures for 0.0, 0.25, 0.50,0.75 and 1.00 mole fractions x{sub j}'s of 1-propanol under 9.1 GHz electric field. The slopes {omega}({tau}{sub 2} + {tau}{sub 1}) and intercepts {omega}{sup 2}{tau}{sub 2}{tau}{sub 1} of the analytical straight line equations used to estimate {tau}{sub 2} and {tau}{sub 1} were derived from Bergmann's equation [U. Saha, S.K. Sit, R.C. Basak, S. Acharyya, J. Phys. D: Appl. Phys. 27 (1994) 596] based on two Debye type dispersion model of binary polar mixture. The systems 3-bromoaniline in C{sub 6}H{sub 6} and 1-propanol in C{sub 6}H{sub 6} show {tau}{sub 2} and {tau}{sub 1} only at 47 deg. C temperature like 3-bromoaniline + 1-propanol in C{sub 6}H{sub 6} at 20 and 47 deg. C temperatures for 0.25 and 0.50 mole fractions x{sub j}'s of 1-propanol. The binary polar mixture for x{sub j} = 0.75 of 1-propanol is an exception exhibiting double relaxation times at all the experimental temperatures. The relative contributions c{sub 1} and c{sub 2} due to {tau}{sub 1} and {tau}{sub 2} for eight non-rigid systems were calculated from Froehlich's equation as well as graphical plots of {chi}{sup '}{sub ijk}/{chi}{sub 0ijk}-w{sub jk} and {chi}{sup ''}{sub ijk}/{chi}{sub 0ijk}-w{sub jk} curve at w{sub jk}{yields}0. c{sub 1} and c{sub 2} are positive for Froehlich's method whereas most of the c{sub 2}'s are negative for graphical method. The dipole moments {mu}{sub 2} and {mu}{sub 1} for all the systems are calculated from

  10. MediaTracker system

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval, D. M. (Dana M.); Strittmatter, R. B. (Richard B.); Abeyta, J. D. (Joline D.); Brown, J. (John); Marks, T. (Thomas), Jr.; Martinez, B. J. (Benny J.); Jones, D. B. (Dana Benelli); Hsue, W.

    2004-01-01

    The initial objectives of this effort were to provide a hardware and software platform that can address the requirements for the accountability of classified removable electronic media and vault access logging. The Media Tracker system software assists classified media custodian in managing vault access logging and Media Tracking to prevent the inadvertent violation of rules or policies for the access to a restricted area and the movement and use of tracked items. The MediaTracker system includes the software tools to track and account for high consequence security assets and high value items. The overall benefits include: (1) real-time access to the disposition of all Classified Removable Electronic Media (CREM), (2) streamlined security procedures and requirements, (3) removal of ambiguity and managerial inconsistencies, (4) prevention of incidents that can and should be prevented, (5) alignment with the DOE's initiative to achieve improvements in security and facility operations through technology deployment, and (6) enhanced individual responsibility by providing a consistent method of dealing with daily responsibilities. In response to initiatives to enhance the control of classified removable electronic media (CREM), the Media Tracker software suite was developed, piloted and implemented at the Los Alamos National Laboratory beginning in July 2000. The Media Tracker software suite assists in the accountability and tracking of CREM and other high-value assets. One component of the MediaTracker software suite provides a Laboratory-approved media tracking system. Using commercial touch screen and bar code technology, the MediaTracker (MT) component of the MediaTracker software suite provides an efficient and effective means to meet current Laboratory requirements and provides new-engineered controls to help assure compliance with those requirements. It also establishes a computer infrastructure at vault entrances for vault access logging, and can

  11. Social Media Marketing in Russia

    OpenAIRE

    Olgskaya, Kristina

    2017-01-01

    Social media marketing involves the use of social media for connecting with prospective consumers. The study focuses on explaining such notions like social media marketing (SMM), types of SMM, differences between social media and traditional marketing, social media marketing plan, development ways of strategic social media marketing plan and why strategy may fail. This thesis also presents research in Russian social network – Vkontakte, where promotion of Mechanical Engineering programme ...

  12. CLASSICAL MEDIA RELATIONS AND NEW MEDIA RELATIONS IN SPORT

    Directory of Open Access Journals (Sweden)

    Alexandru Lucian MIHAI

    2014-06-01

    Full Text Available Media relations in sport mean maintenance of networks and positive relationships with people in the media to obtain positive media exposure for a sport product (informal and formal information sessions with media representatives. Because of the pervasive influence the media has on marketing success, sport marketers must make concerted efforts to create a positive relationship between their sport event and the media. They may accomplish this by providing the media with press releases, having news conferences, having media-day events (in which the media are invited to interact with the players, coaches, and administrators, providing media guides for the respective sport events and so on. Each of these activities promotes active involvement from the media, which will subsequently contribute to relationship building with the community.

  13. CLASSICAL MEDIA RELATIONS AND NEW MEDIA RELATIONS IN SPORT

    Directory of Open Access Journals (Sweden)

    Alexandru Lucian MIHAI

    2014-06-01

    Full Text Available Media relations in sport mean maintenance of networks and positive relationships with people in the media to obtain positive media exposure for a sport product (informal and formal information sessions with media representatives. Because of the pervasive influence the media has on marketing success, sport marketers must make concerted efforts to create a positive relationship between their sport event and the media. They may accomplish this by providing the media with press releases, having news conferences, having media-day events (in which the media are invited to interact with the players, coaches, and administrators, providing media guides for the respective sport events and so on. Each of these activities promotes active involvement from the media, which will subsequently contribute to relationship building with the community.

  14. Turkish Press in Social Media

    OpenAIRE

    AYTEN, Adem

    2013-01-01

    Social media, is one of the most researched facts today by the commications fellows. To get in use by Web 2.0 social media becomes common due to the rise of using mobile technologies. Instead of competing with traditional media and being an alternative media, social media is a new media that traditional media can transfer its content to it and can benefit its advantages. Indeed,the traditional media carried its content to the websites to access of their readers/listeners/watchers to compete ...

  15. Media Literacy in Montenegro

    Directory of Open Access Journals (Sweden)

    Jelena Perovic

    2015-12-01

    Full Text Available Few countries in the world have introduced media education into their curriculums. Montenegro became one of them in 2009, when “media literacy” was introduced as an optional subject for 16 and 17 year old students of Gymnasium high schools. This article presents the findings of the first and only research conducted so far on media education in Montenegro. It is a national case study which examines the potential of media education to change the school culture and accelerate education system reform towards embracing the new digital education paradigm in the future. The focus is on the results of research conducted through in-depth interviews with media literacy teachers all over the country. Despite the many challenges, all teachers identify the potential of media education to strengthen some of the key competences of the students and to improve their motivation and academic performance. They also identify potential to change positively school culture by transforming teachers into “cultural mediators” (Morcellini, 2007 and by supporting the formation of a “participative culture” (Jenkins & Kelley, 2013 in schools. This research recommends focusing education reform on spreading the media education pedagogy to the entire curriculum in order to embrace the new digital education paradigm in the future.

  16. Social Media and Bullshit

    Directory of Open Access Journals (Sweden)

    Rasmus Kleis Nielsen

    2015-04-01

    Full Text Available To understand the role of social media in society, we have to understand how social media are understood. We need to analyze how different actors and organizations see and think about technology, the forms of knowledge that people draw on as they make sense of, develop, and use social media. Central among these is bullshit. This short essay discusses bullshit as defined by the philosopher Harry Frankfurt as statements made with little or no concern for their truth-value or justification and argues that social media are accompanied by unusually large amounts of bullshit for two reasons. First, they confront us with epistemological problems and are hard to understand. Second, there is a large demand for knowledge about what they mean, a powerful political economy that generates a lot of statements about social media, including substantial amounts of bullshit. Given the rapid development of social media and their growing importance, this is unlikely to change in the near future. Bullshit is here to stay, and we need to take it seriously intellectually and analytically to understand social media.

  17. Nonpolar m-plane GaN/AlGaN heterostructures with intersubband transitions in the 5-10 THz band.

    Science.gov (United States)

    Lim, C B; Ajay, A; Bougerol, C; Haas, B; Schörmann, J; Beeler, M; Lähnemann, J; Eickhoff, M; Monroy, E

    2015-10-30

    This paper assesses intersubband (ISB) transitions in the 1-10 THz frequency range in nonpolar m-plane GaN/AlGaN multi-quantum-wells deposited on free-standing semi-insulating GaN substrates. The quantum wells (QWs) were designed to contain two confined electronic levels, decoupled from the neighboring wells. Structural analysis reveals flat and regular QWs in the two perpendicular in-plane directions, with high-angle annular dark-field scanning transmission electron microscopy images showing inhomogeneities of the Al composition in the barriers along the growth axis. We do not observe extended structural defects (stacking faults or dislocations) introduced by the epitaxial process. Low-temperature ISB absorption from 1.5 to 9 THz (6.3-37.4 meV) is demonstrated, covering most of the 7-10 THz band forbidden to GaAs-based technologies.

  18. Band-edge optical transitions in a nonpolar-plane GaN substrate: exciton-phonon coupling and temperature effects

    Science.gov (United States)

    Wang, M. Z.; Xu, S. J.

    2016-09-01

    We present a detailed investigation of the band-edge optical transitions involving the interacting exciton-phonon system, especially first-order longitudinal optical (LO) phonon-assisted luminescence of bound and free excitons in m- and c-plane GaN substrates in a low temperature range from 4 K to 40 K. The main luminescence features of all of the three kinds of excitons can be well described by the theoretical models that take exciton-LO-phonon coupling into account. The effective Bohr radii of the excitons play a key role in determining the Huang-Rhys factor characterizing the exciton-LO-phonon coupling strength in GaN. An interesting oscillatory structure is found to appear in the low-temperature luminescence spectra of the nonpolar-plane GaN substrate, which needs to be clarified by further investigations.

  19. Morphology and composition controlled growth of polar c-axis and nonpolar m-axis well-aligned ternary III-nitride nanotube arrays

    Science.gov (United States)

    Li, Huijie; Zhao, Guijuan; Kong, Susu; Han, Dongyue; Wei, Hongyuan; Wang, Lianshan; Chen, Zhen; Yang, Shaoyan

    2015-10-01

    Control over the nanostructure morphology and growth orientation is in high demand for fundamental research and technological applications. Herein we report a general strategy to fabricate polar c-axis and nonpolar m-axis well-aligned III-nitride ternary nanotube arrays with controllable morphologies and compositions. By depositing AlN on the InN nanorod array templates and thermally removing the InN templates, InAlN nanotubes can be obtained. Polar c-axis and nonpolar m-axis nanotubes were formed on the c- and r-plane sapphire substrates, respectively. The nanotubes are single crystalline and highly ordered on the substrates, as revealed by X-ray diffraction, electron microscopy, and selected area electron microscopy characterization. It was found that the In droplets on top of the InN nanorods play a critical role in controlling the morphology of the nanotubes. By keeping or removing the In droplets, the obtained nanotubes exhibited both ends open or only one end open. And by varying the AlN deposition temperature, the In composition in the nanotubes can be changed from 0 to 0.29. The nanotube synthesis method is simple and can be applied to the formation of other III-nitride ternary (InGaN, and AlGaN) or quaternary (InAlGaN) alloy nanotube arrays.Control over the nanostructure morphology and growth orientation is in high demand for fundamental research and technological applications. Herein we report a general strategy to fabricate polar c-axis and nonpolar m-axis well-aligned III-nitride ternary nanotube arrays with controllable morphologies and compositions. By depositing AlN on the InN nanorod array templates and thermally removing the InN templates, InAlN nanotubes can be obtained. Polar c-axis and nonpolar m-axis nanotubes were formed on the c- and r-plane sapphire substrates, respectively. The nanotubes are single crystalline and highly ordered on the substrates, as revealed by X-ray diffraction, electron microscopy, and selected area electron microscopy

  20. Growth of polar and non-polar nitride semiconductor quasi-substrates by hydride vapor phase epitaxy for the development of optoelectronic devices by molecular beam epitaxy

    Science.gov (United States)

    Moldawer, Adam Lyle

    The family of nitride semiconductors has had a profound influence on the development of optoelectronics for a large variety of applications. However, as of yet there are no native substrates commercially available that are grown by liquid phase methods as with Si and GaAs. As a result, the majority of electronic and optoelectronic devices are grown heteroepitaxially on sapphire and SiC. This PhD research addresses both the development of polar and non-polar GaN and AIN templates by Hydride Vapor Phase Epitaxy (HVPE) on sapphire and SiC substrates, as well as the growth and characterization of optoelectronic devices on these templates by molecular beam epitaxy (MBE). Polar and non-polar GaN templates have been grown in a vertical HVPE reactor on the C- and R-planes of sapphire respectively. The growth conditions have been optimized to allow the formation for thick (50um) GaN templates without cracks. These templates were characterized structurally by studying their surface morphologies by SEM and AFM, and their structure through XRD and TEM. The polar C-plane GaN templates were found to be atomically smooth. However, the surface morphology of the non-polar GaN films grown on the R-plane of sapphire were found to have a facetted surface morphology, with the facets intersecting at 120° angles. This surface morphology reflects an equilibrium growth, since the A-plane of GaN grows faster than the M-planes of GaN due to the lower atomic density of the plane. For the development of deep-UV optoelectronics, it is required to grow AIGaN quantum wells on AIN templates. However, since AIN is a high melting point material, such templates have to be grown at higher temperatures, close to half the melting point of the material (1500 °C). As these temperatures cannot be easily obtained by traditional furnace heating, an HVPE reactor has been designed to heat the substrate inductively to these temperatures. This apparatus has been used to grow high-quality, transparent AIN films

  1. Doping dependent blue shift and linewidth broadening of intersubband absorption in non-polar m-plane AlGaN/GaN multiple quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Kotani, Teruhisa, E-mail: tkotani@iis.u-tokyo.ac.jp [Institute for Nano Quantum Information Electronics, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Advanced Technology Research Laboratories, Sharp Corporation, 2613-1 Ichinomoto-cho, Tenri, Nara 632-8567 (Japan); Arita, Munetaka [Institute for Nano Quantum Information Electronics, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Arakawa, Yasuhiko [Institute for Nano Quantum Information Electronics, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2015-09-14

    Blue shift and broadening of the absorption spectra of mid-infrared intersubband transition in non-polar m-plane AlGaN/GaN 10 quantum wells were observed with increasing doping density. As the doping density was increased from 6.6 × 10{sup 11} to 6.0 × 10{sup 12 }cm{sup −2} per a quantum well, the intersubband absorption peak energy shifted from 274.0 meV to 302.9 meV, and the full width at half maximum increased from 56.4 meV to 112.4 meV. Theoretical calculations reveal that the blue shift is due to many body effects, and the intersubband linewidth in doped AlGaN/GaN QW is mainly determined by scattering due to interface roughness, LO phonons, and ionized impurities.

  2. Social Media and Bullshit

    OpenAIRE

    Rasmus Kleis Nielsen

    2015-01-01

    To understand the role of social media in society, we have to understand how social media are understood. We need to analyze how different actors and organizations see and think about technology, the forms of knowledge that people draw on as they make sense of, develop, and use social media. Central among these is bullshit. This short essay discusses bullshit as defined by the philosopher Harry Frankfurt as statements made with little or no concern for their truth-value or justification and a...

  3. Media and ICT

    DEFF Research Database (Denmark)

    to the question of how the presence of media and ICT in and outside schools both change and qualify educational practice as well as how the cooperation between media, cultures, aesthetics and social relations affect and support new demands on education. The book represents different academic perspectives......Media and information and communication technologies (ICTs) have in the past decades been placed firmly on the educational agenda, and will continue to maintain this position, not least as catalysts for educational change. This issue is reflected in the anthology as it aims to respond...

  4. Open Media Science

    DEFF Research Database (Denmark)

    Møller Moltke Martiny, Kristian; Pedersen, David Budtz; Hansted, Allan Alfred Birkegaard

    2016-01-01

    In this article, we present three challenges to the emerging Open Science (OS) movement: the challenge of communication, collaboration and cultivation of scientific research. We argue that to address these challenges OS needs to include other forms of data than what can be captured in a text...... and extend into a fully-fledged Open Media movement engaging with new media and non-traditional formats of science communication. We discuss two cases where experiments with open media have driven new collaborations between scientists and documentarists. We use the cases to illustrate different advantages...

  5. Open Media Science

    DEFF Research Database (Denmark)

    Møller Moltke Martiny, Kristian; Pedersen, David Budtz; Hansted, Allan Alfred Birkegaard

    2016-01-01

    In this article, we present three challenges to the emerging Open Science (OS) movement: the challenge of communication, collaboration and cultivation of scientific research. We argue that to address these challenges OS needs to include other forms of data than what can be captured in a text...... and extend into a fully-fledged Open Media movement engaging with new media and non-traditional formats of science communication. We discuss two cases where experiments with open media have driven new collaborations between scientists and documentarists. We use the cases to illustrate different advantages...

  6. Ethics and social media.

    Science.gov (United States)

    Milton, Constance L

    2014-10-01

    Nurses' use of social media has increased significantly with growing numbers of media-sharing opportunities, platforms, and emerging forms of electronic applications. With the proliferation, opportunities and limitations surface regarding the responsibilities and accountability that nurses have in choosing technology applications with an embedded philosophical ethos that is consistent with the discipline's societal mandate of serving humankind in ways that honor human dignity. This article begins a discussion addressing possible disciplinary obligations and responsibilities for the implementation of social media platforms and possible implications for its future use in the discipline of nursing.

  7. Social Media and Bullshit

    OpenAIRE

    2015-01-01

    To understand the role of social media in society, we have to understand how social media are understood. We need to analyze how different actors and organizations see and think about technology, the forms of knowledge that people draw on as they make sense of, develop, and use social media. Central among these is bullshit. This short essay discusses bullshit as defined by the philosopher Harry Frankfurt as statements made with little or no concern for their truth-value or justification and a...

  8. Media violence and youth.

    Science.gov (United States)

    Beresin, E V

    1999-06-01

    This column reviews the literature on violence in the media and its effects on youth. The author summarizes the findings of naturalistic, longitudinal, and population-based studies conducted over the last 30 years. The literature provides compelling evidence that exposure of media violence to children plays a major role in the etiology of aggressive behavior. Psychiatrists can facilitate primary prevention of violence in our society by discussing the problem of media violence with parents, medical students, residents, and allied health and school professionals.

  9. An absorbing microwave micro-solid-phase extraction device used in non-polar solvent microwave-assisted extraction for the determination of organophosphorus pesticides

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ziming, E-mail: wangziming@jlu.edu.cn [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Zhao Xin; Xu Xu; Wu Lijie; Su Rui; Zhao Yajing; Jiang Chengfei; Zhang Hanqi [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Ma Qiang [Chinese Academy of Inspection and Quarantine, Beijing 100123 (China); Lu Chunmei [College of Technology Center, Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun 130062 (China); Dong Deming [College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

    2013-01-14

    Highlights: Black-Right-Pointing-Pointer An absorbing microwave {mu}-SPE device packed with activated carbon was used. Black-Right-Pointing-Pointer Absorbing microwave {mu}-SPE device was made and used to enrich the analytes. Black-Right-Pointing-Pointer Absorbing microwave {mu}-SPE device was made and used to heat samples directly. Black-Right-Pointing-Pointer MAE-{mu}-SPE was applied to the extraction of OPPs with non-polar solvent only. - Abstract: A single-step extraction-cleanup method, including microwave-assisted extraction (MAE) and micro-solid-phase extraction ({mu}-SPE), was developed for the extraction of ten organophosphorus pesticides in vegetable and fruit samples. Without adding any polar solvent, only one kind of non-polar solvent (hexane) was used as extraction solvent in the whole extraction step. Absorbing microwave {mu}-SPE device, was prepared by packing activated carbon with microporous polypropylene membrane envelope, and used as not only the sorbent in {mu}-SPE, but also the microwave absorption medium. Some experimental parameters effecting on extraction efficiency was investigated and optimized. 1.0 g of sample, 8 mL of hexane and three absorbing microwave {mu}-SPE devices were added in the microwave extraction vessel, the extraction was carried out under 400 W irradiation power at 60 Degree-Sign C for 10 min. The extracts obtained by MAE-{mu}-SPE were directly analyzed by GC-MS without any clean-up process. The recoveries were in the range of 93.5-104.6%, and the relative standard deviations were lower than 8.7%.

  10. Mediatization Theory and Digital Media

    DEFF Research Database (Denmark)

    Finnemann, Niels Ole

    2011-01-01

    In the 20th century, the term "media logic" was introduced to denote the influence of independent mass media on political systems and other institutions. In recent years the idea has been reworked and labelled "mediatization" to widen the framework by including new media and new areas of applicat......In the 20th century, the term "media logic" was introduced to denote the influence of independent mass media on political systems and other institutions. In recent years the idea has been reworked and labelled "mediatization" to widen the framework by including new media and new areas...... new trajectories made possible by these media, which have led into a new media matrix built around the internet and mobile devices. It will be argued that the new media matrix cannot be understood from a point of view defined by the framework of 20th century mass media because digital media open new...

  11. Media and Security Team

    Data.gov (United States)

    Federal Laboratory Consortium — The Media And Security Team led by Prof. Min Wu was established in Fall 2001 at University of Maryland, College Park. A number of research and education activities...

  12. Research in Learning Media

    NARCIS (Netherlands)

    Westera, Wim

    2009-01-01

    Westera, W. (2009). Research in Learning Media, CELSTEC lab. Presentation on behalf of a delegation of Teleac/NOT and the scientific board of the Veringa chair. February, 13, 2009, Heerlen, The Netherlands: Open University of the Netherlands.

  13. Mixed-Media Owls

    Science.gov (United States)

    Schultz, Kathy

    2010-01-01

    The fun of creating collages is there are unlimited possibilities for the different kinds of materials one can use. In this article, the author describes how her eighth-grade students created an owl using mixed media.

  14. Creative Digital Media Practices

    DEFF Research Database (Denmark)

    Frølunde, Lisbeth

    on collaboration (Benkler, 2006). The shift toward visual modes and digital media practices pose many pedagogical challenges for academics. I want to raise questions on how to teach “dialogically” with and through creative, digital media practices based on my plans for a course in Fall, 2011, where students......The presentation reviews the interplay of dialogic (Bakhtin, 1981) and multimodal theories on media production practices, with attention to visual communication (Kress and van Leeuwen, 2001, 2006). This theoretical approach aids in reflecting on digital media practices as novel (new) sign systems...... and personal levels. The discussion includes pedagogical issues in regards to the upcoming university course, such as: how to encourage dialogic reflection between students as authors and viewers of digital stories, and how to support their application and integration of visual and dialogic communication...

  15. Subsidizing Media Innovation

    DEFF Research Database (Denmark)

    Kammer, Aske; Hobel, Emil

    ). Qualitative Media Analysis (2nd Ed.). Los Angeles: Sage. Esping-Andersen, G. (1990). The Three Worlds of Welfare Capitalism. Cambridge: Polity Press. Kammer, A. (forthcoming/2016). Market Structure and Innovation Policies in Denmark. In H. v. Kranenburg (Ed.), Innovation Policies in the European News......When the Danish Parliament revised the media-subsidy framework in 2013/2014, one of the new initiatives was the introduction of a pool of funding earmarked to establishing and developing new news media – the so-called “innovation fund”. So, as the news industry struggles to keep journalism a viable...... and economically sustainable activity, the institutionalization of financial support for media innovation constitute one way for policy makers to bring (parts of) the journalistic environment up-to-date with the digital age, thereby improving the conditions for an informed citizenry in the future (Kammer...

  16. Consolidating Social Media Strategies

    DEFF Research Database (Denmark)

    Gyimóthy, Szilvia; Munar, Ana Maria; Larson, Mia

    2014-01-01

    This study revisits and integrates the insights of recent studies on emergent social media strategies deployed by destination and event management organisations. In a comparative analysis Munar (2012) identified four generic approaches pursued by national tourism boards in the Nordic region, while...... Gyimóthy & Larson (2014) portrayed three digital value co-creation strategies deployed by festival social media. Both frameworks provided novel analytical typologies which identified a series of categories (mimetic, analytic, immersion, advertising and insourcing, crowdsourcing and community consolidation......). This paper discusses the complementary nature of these conceptual proposals and advances an integrated conceptual framework of social media strategies. Based on the empirical findings of a case study that revisits evolving digital and social media strategies of European DMOs this paper maps the dynamics...

  17. Stochastic porous media equations

    CERN Document Server

    Barbu, Viorel; Röckner, Michael

    2016-01-01

    Focusing on stochastic porous media equations, this book places an emphasis on existence theorems, asymptotic behavior and ergodic properties of the associated transition semigroup. Stochastic perturbations of the porous media equation have reviously been considered by physicists, but rigorous mathematical existence results have only recently been found. The porous media equation models a number of different physical phenomena, including the flow of an ideal gas and the diffusion of a compressible fluid through porous media, and also thermal propagation in plasma and plasma radiation. Another important application is to a model of the standard self-organized criticality process, called the "sand-pile model" or the "Bak-Tang-Wiesenfeld model". The book will be of interest to PhD students and researchers in mathematics, physics and biology.

  18. Streaming media bible

    National Research Council Canada - National Science Library

    Mack, Steve

    2002-01-01

    This book "tells you everything you need to know to produce professional-quality streaming media for the Internet, from an overview of the available systems and tools to high-end techniques for top quality results...

  19. TECHNETIUM SORPTION MEDIA REVIEW

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN JB; KELLY SE; ROBBINS RA; ADAMS RD; THORSON MA; HAASS CC

    2011-08-25

    This report presents information and references to aid in the selection of 99Tc sorption media for feasibility studies regarding the removal of 99Tc from Hanford's low activity waste. The report contains literature search material for sorption media (including ion exchange media) for the most tested media to date, including SuperLig 639, Reillex HPQ, TAM (Kruion), Purolite A520E and A530E, and Dowex 1X8. The U.S. Department of Energy (DOE), Office of River Protection (ORP) is responsible for management and completion of the River Protection Project (RPP) mission, which comprises both the Hanford Site tank farms and the Waste Treatment and Immobilization Plant (WTP). The RPP mission is to store, retrieve and treat Hanford's tank waste; store and dispose of treated wastes; and close the tank farm waste management areas and treatment facilities in a safe, environmentally compliant, cost-effective and energy-effective manner.

  20. Functionally Graded Media

    OpenAIRE

    Campos, Cédric M.; Epstein, Marcelo; De León, Manuel

    2007-01-01

    The notions of uniformity and homogeneity of elastic materials are reviewed in terms of Lie groupoids and frame bundles. This framework is also extended to consider the case Functionally Graded Media, which allows us to obtain some homogeneity conditions.

  1. Media studies for scientists

    CERN Multimedia

    2002-01-01

    "Science, with its inherent uncertainties, can be hard to put across to the public. But blaming 'sloppy' journalism is too easy. If researchers are to make their points effectively, they should learn more about how the media work" (1 page).

  2. Spotlight on the media

    CERN Document Server

    2007-01-01

    Do you want to know more about how the media works, how to deal with journalists? How to maximise opportunity and minimise threat? Then please join us on 22 November. This session will cover how to work effectively with the media, including print, radio and TV. You’ll get an insight into how journalists and news rooms operate. You’ll learn to recognise both soft balls and traps - and develop the techniques for dealing with them. The challenges of explaining CERN to any media outlet will be dealt with too. This interactive presentation, given by Jessica Pryce-Jones, Managing Director of the consultancy firm iOpener Ltd, and Nisha Pillai, news anchor for BBC World, will be illustrated with various case studies. How to deal with the media: maximising opportunity and minimising threat Thursday 22 November, from 4.30 pm, Main Auditorium, Bldg. 500 Coffee break before the event at 4.00 pm

  3. Consolidating Social Media Strategies

    DEFF Research Database (Denmark)

    Gyimóthy, Szilvia; Munar, Ana Maria; Larson, Mia

    2014-01-01

    This study revisits and integrates the insights of recent studies on emergent social media strategies deployed by destination and event management organisations. In a comparative analysis Munar (2012) identified four generic approaches pursued by national tourism boards in the Nordic region, while...... Gyimóthy & Larson (2014) portrayed three digital value co-creation strategies deployed by festival social media. Both frameworks provided novel analytical typologies which identified a series of categories (mimetic, analytic, immersion, advertising and insourcing, crowdsourcing and community consolidation......). This paper discusses the complementary nature of these conceptual proposals and advances an integrated conceptual framework of social media strategies. Based on the empirical findings of a case study that revisits evolving digital and social media strategies of European DMOs this paper maps the dynamics...

  4. Media and Multiplicity

    DEFF Research Database (Denmark)

    Blaagaard, Bolette

    2010-01-01

    In the past few years continental Europe has experienced a resurgence of right-wing party politics, nationalism and xenophobia. In this nationalist revival the media and advanced communications technologies have played a significant role, as evidenced by the debates following cases...... explores the tensions within the relation between journalistic practice and the construction of the idea of the nation and the multiplicity of media and cultures which inhabit the spheres of journalism and nation....

  5. On commercial media bias

    OpenAIRE

    Germano, Fabrizio

    2008-01-01

    Within the spokes model of Chen and Riordan (2007) that allows for non-localized competition among arbitrary numbers of media outlets, we quantify the effect of concentration of ownership on quality and bias of media content. A main result shows that too few commercial outlets, or better, too few separate owners of commercial outlets can lead to substantial bias in equilibrium. Increasing the number of outlets (commercial and non-commercial) tends to bring down this bias; but the strongest ef...

  6. Digital Media Ethics

    DEFF Research Database (Denmark)

    Ess, Charles

    Provides a philosophical-ethical "toolkit" for analyzing central ethical issues evoked by our use of new media, including privacy, copyright, violent and sexual content online, and cross-cultural communication online.......Provides a philosophical-ethical "toolkit" for analyzing central ethical issues evoked by our use of new media, including privacy, copyright, violent and sexual content online, and cross-cultural communication online....

  7. Drupal 7 media

    CERN Document Server

    Tal, Liran

    2013-01-01

    This is a practical, hands-on guide packed with examples that will help you build rich Drupal 7 media web applications.If you are a Drupal site builder and you wish to spice up your web applications with rich media content, then this book is for you. A basic understanding of HTML, JavaScript, and basic PHP module development in Drupal would be helpful, but is not necessary.

  8. Optimal Internet Media Selection

    OpenAIRE

    Peter J. Danaher; Janghyuk Lee; Laoucine Kerbache

    2010-01-01

    In this study we develop a method that optimally selects online media vehicles and determines the number of advertising impressions that should be purchased and then served from each chosen website. As a starting point, we apply Danaher's [Danaher, P. J. 2007. Modeling page views across multiple websites with an application to Internet reach and frequency prediction. (3) 422–437] multivariate negative binomial distribution (MNBD) for predicting online media exposure distributions. The MNBD is...

  9. Digital Media Ethics

    DEFF Research Database (Denmark)

    Ess, Charles

    Provides a philosophical-ethical "toolkit" for analyzing central ethical issues evoked by our use of new media, including privacy, copyright, violent and sexual content online, and cross-cultural communication online.......Provides a philosophical-ethical "toolkit" for analyzing central ethical issues evoked by our use of new media, including privacy, copyright, violent and sexual content online, and cross-cultural communication online....

  10. Investigating media stories

    Science.gov (United States)

    Lowe, Stuart

    2008-08-01

    Perceived lapses of fact or emphasis in popular science coverage in the media can irritate active researchers: concern for establishing facts and details of scientific arguments can override appreciation of the value of a good popular story in the press. A programme to educate early-career astronomers about the different goals and priorities of the wider media is equipping research stars of the future to get their messages across.

  11. Social Media Cocreation Strategies

    DEFF Research Database (Denmark)

    Gyimóthy, Szilvia; Larson, Mia

    2015-01-01

    This paper explores how social media becomes a part of integrated marketing communications of festival organizations. The purpose of this paper is to conceptualize the co-creation of festival experiences online by comparing managerial strategies and communicative patterns of three large....... Based on the empirical findings, we propose an analytical framework to improve our understanding of the management of social media communications, offering three distinct value co-creation strategies in a festival context....

  12. Otitis media: conceptos actuales

    Directory of Open Access Journals (Sweden)

    Hernán Sierra Fernández

    2004-09-01

    Full Text Available La otitis media aguda es uno de los motivos más frecuentes de consulta en la edad pediátrica. Los gérmenes que con mayor frecuencia se aíslan en el oído medio de estos pacientes son el Streptococcus pneumoniae, el Haemophilus influenzae, la Moraxella catarrhalis y el Streptococcus pyogenes. El patrón de resistencia antibiótica de estas bacterias varía dependiendo de la región geográfica. y es la base fundamental para establecer recomendaciones terapéuticas. El análisis en Costa Rica. de la microbiología de la otitis media aguda, otitis media recurrente y otitis media catalogada como falla terapéutica, sugiere que la amoxicilina en una dosis de 50 mg/Kg/día por 10 días, debe ser considerada el antibiótico de primera línea en los casos de otitis media aguda. En los pacientes con otitis media recurrente, falla antimicrobiana o cuando se sospeche la presencia de un Streptococcus pneumoniae resistente a la penicilina, se debe considerar el uso de amoxicilina en dosis más elevadas, amoxicilina con ácido clavulánico, macrólidos o ceftrlaxona.

  13. Media, risk and science

    CERN Document Server

    Allan, Stuart

    2002-01-01

    How is science represented by the media? Who defines what counts as a risk, threat or hazard, and why? In what ways do media images of science shape public perceptions? What can cultural and media studies tell us about current scientific controversies? "Media, Risk and Science" is an exciting exploration into an array of important issues, providing a much needed framework for understanding key debates on how the media represent science and risk. In a highly effective way, Stuart Allan weaves together insights from multiple strands of research across diverse disciplines. Among the themes he examines are: the role of science in science fiction, such as "Star Trek"; the problem of 'pseudo-science' in "The X-Files"; and how science is displayed in science museums. Science journalism receives particular attention, with the processes by which science is made 'newsworthy' unravelled for careful scrutiny. The book also includes individual chapters devoted to how the media portray environmental risks, HIV-AIDS, food s...

  14. Self-media

    DEFF Research Database (Denmark)

    Fausing, Bent

    2015-01-01

    The self and identity are not only topics related to the selfies. They are connected to the development of media since the renaissance, the self-media. This is the thesis of the following. The subject, the self, is most clearly exposed in the face, and face and identity becomes important in the m......The self and identity are not only topics related to the selfies. They are connected to the development of media since the renaissance, the self-media. This is the thesis of the following. The subject, the self, is most clearly exposed in the face, and face and identity becomes important...... in the media since the renaissance. The selfies is just the newest development is this tradition, which began with the invention of the mirror, the book (printing), and the small painting. They all put the subject as both maker and receiver in the center. It was the beginning of the modern subject....... The development continued throughout the coming centuries. The selfies is the newest creation to discover, explore, visualize and find the self of the subject. The following will thus emphasis the self, the face, where the self is most noticeably expressed and seen, and the self-media, where the individual can...

  15. The social media image

    Directory of Open Access Journals (Sweden)

    Nadav Hochman

    2014-08-01

    Full Text Available How do the organization and presentation of large-scale social media images recondition the process by which visual knowledge, value, and meaning are made in contemporary conditions? Analyzing fundamental elements in the changing syntax of existing visual software ontology—the ways current social media platforms and aggregators organize and categorize social media images—this article relates how visual materials created within social media platforms manifest distinct modes of knowledge production and acquisition. First, I analyze the structure of social media images within data streams as opposed to previous information organization in a structured database. While the database has no pre-defined notions of time and thus challenges traditional linear forms, the data stream re-emphasizes the linearity of a particular data sequence and activates a set of new relations to contemporary temporalities. Next, I show how these visual arrangements and temporal principles are manifested and discussed in three artworks: “Untitled” (Perfect Lovers by Felix Gonzalez-Torres (1991, The Clock by Christian Marclay (2011, and Last Clock by Jussi Ängeslevä and Ross Cooper (2002. By emphasizing the technical and poetic ways in which social media situate the present as a “thick” historical unit that embodies multiple and synchronous temporalities, this article illuminates some of the conditions, challenges, and tensions between former visual structures and current ones, and unfolds the cultural significations of contemporary big visual data.

  16. Mixed-Media File Systems

    NARCIS (Netherlands)

    Bosch, Hendrikus Gerardus Petrus

    1999-01-01

    This thesis addresses the problem of implementing mixed-media storage systems. In this work a mixed-media file system is defined to be a system that stores both conventional (best-effort) file data and real-time continuous-media data. Continuous-media data is usually bulky, and servers storing and r

  17. Media Education: An Indian Perspective.

    Science.gov (United States)

    Kumar, Keval Joe

    This paper provides both a preliminary analysis of a survey on media education in India, and reviews of the research on media education in the western world, the limited media education research already done in India, and the more extensive research that has been done on the sociology of Indian youth and the media. The purpose of the survey was to…

  18. Media in the Future Tense.

    Science.gov (United States)

    Wiseman, Molly J.

    The purpose of this paper is to provide teachers with a rationale for teaching the mass media. It also contains a discussion of different methods to be used in teaching the media. The influence of the media on contemporary society is examined and the importance of the mass media in the educational process is stressed. In addition, the paper…

  19. Advertising media selection and planning

    NARCIS (Netherlands)

    Moorman, M.; Neijens, P.C.; Smit, E.G.; Belch, M.A.; Belch, G.E.

    2010-01-01

    Reach, frequency, and timing are key concepts in selecting TV, radio, newspapers, magazines, out-of-home, direct mail, Internet, and other media for advertising campaigns. We discuss these concepts and their role in media selection and media planning processes. We also describe media and audience fa

  20. Rotational Diffusion of Nonpolar and Ionic Solutes in 1-Alkyl-3-methylimidazolium Tetrafluoroborate-LiBF4 Mixtures: Does the Electrolyte Induce the Structure-Making or Structure-Breaking Effect?

    Science.gov (United States)

    Prabhu, Sugosh R; Dutt, G B

    2015-12-03

    Rotational diffusion of three structurally similar solutes, 9-phenylanthracene (9-PA), fluorescein (FL), and rhodamine 110 (R110), has been investigated in 1-butyl-3-methylimidazolium tetrafluoroborate-lithium tetrafluoroborate ([BMIM][BF4]-LiBF4) mixtures to understand the influence of the added electrolyte on the mobility of nonpolar, anionic, and cationic solute molecules. It has been observed that the reorientation times of the nonpolar solute 9-PA become progressively shorter with an increase in the concentration of LiBF4 at a given viscosity (η) and temperature (T). In the case of ionic solutes also, a decrease in the reorientation times has been observed upon the addition of the electrolyte compared to those obtained in the neat ionic liquid at a given η/T. However, this decrease is found to be independent of [LiBF4]. 9-PA being a nonpolar solute is located in the nonpolar domains of the ionic liquid. An enhancement in [LiBF4] leads to an increase in the sizes of the nonpolar domains resulting in the faster rotation of the solute. Anionic solute FL and cationic solute R110, which are located in the ionic region experience specific interactions with the cation and anion of the ionic liquid, respectively. In the presence of electrolyte, however, the strengths of these specific interactions diminish as the ions of the ionic liquid are not readily accessible to the solute molecules due to the organized structure, which results in faster rotation. These observations suggest that addition of LiBF4 induces a structure-making effect in the ionic liquid.

  1. The Romanian Media - An Overview

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available The Romanian Media Sector from the last 17 years can be described as a dinamic one. In the current study, which is also a part of national report of the Grundtvig 2 project "The Influence of Media in Adult Education Development" 06-G2-94-TM-RO-C, we divided the media sector into: printed media, audio-visual media, media based on web and new media. Within this article, I tried to present a short history, state of the art, as well as the tendencies on short term, for each of them.

  2. Otitis media: conceptos actuales

    Directory of Open Access Journals (Sweden)

    Hernán Sierra Fernández

    2004-09-01

    Full Text Available La otitis media aguda es uno de los motivos más frecuentes de consulta en la edad pediátrica. Los gérmenes que con mayor frecuencia se aíslan en el oído medio de estos pacientes son el Streptococcus pneumoniae, el Haemophilus influenzae, la Moraxella catarrhalis y el Streptococcus pyogenes. El patrón de resistencia antibiótica de estas bacterias varía dependiendo de la región geográfica. y es la base fundamental para establecer recomendaciones terapéuticas. El análisis en Costa Rica. de la microbiología de la otitis media aguda, otitis media recurrente y otitis media catalogada como falla terapéutica, sugiere que la amoxicilina en una dosis de 50 mg/Kg/día por 10 días, debe ser considerada el antibiótico de primera línea en los casos de otitis media aguda. En los pacientes con otitis media recurrente, falla antimicrobiana o cuando se sospeche la presencia de un Streptococcus pneumoniae resistente a la penicilina, se debe considerar el uso de amoxicilina en dosis más elevadas, amoxicilina con ácido clavulánico, macrólidos o ceftrlaxona.Otitis media is one of the most common causes of consultation among the pediatric population. The pathogens most frequently isolated from middle ear fluid are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. Antimicrobial resistance patterns vary by region and their knowledge is considered important in order to achieve proper antimicrobial selection. In Costa Rica the microbiology of patients with acute, recurrent and tteattnent failure otitis media has been recently analyzed. The results of these studies indicate that amoxicillin at 50 mg/kg/day for 10 days should be considered first line of therapy for patients with acute otitis media. In patients with recurrent otitis media, therapeutic failures or in patients at risk of having a penicillin non-susceptible Streptococcus pneumoniae, one of the second line agents should be considered.

  3. Mediatization Theory and Digital Media

    DEFF Research Database (Denmark)

    Finnemann, Niels Ole

    2011-01-01

    of application.  In Section Two the paper discusses different conceptualizations. It is argued that even if they bring new insights, they cannot be unified into one concept, and that they also lack a consistent definition of digital media. Section three provides a definition of digital media in order to identify...... new trajectories made possible by these media, which have led into a new media matrix built around the internet and mobile devices. It will be argued that the new media matrix cannot be understood from a point of view defined by the framework of 20th century mass media because digital media open new......In the 20th century, the term "media logic" was introduced to denote the influence of independent mass media on political systems and other institutions. In recent years the idea has been reworked and labelled "mediatization" to widen the framework by including new media and new areas...

  4. Towards water compatible MIPs for sensing in aqueous media.

    Science.gov (United States)

    Horemans, F; Weustenraed, A; Spivak, D; Cleij, T J

    2012-06-01

    When synthesizing molecularly imprinted polymers (MIPs), a few fundamental principles should be kept in mind. There is a strong correlation between porogen polarity, MIP microenvironment polarity and the imprinting effect itself. The combination of these parameters eventually determines the overall binding behavior of a MIP in a given solvent. In addition, it is shown that MIP binding is strongly influenced by the polarity of the rebinding solvent. Because the use of MIPs in biomedical environments is of considerable interest, it is important that these MIPs perform well in aqueous media. In this article, various approaches are explored towards a water compatible MIP for the target molecule l-nicotine. To this end, the imprinting effect together with the MIP matrix polarity is fine-tuned during MIP synthesis. The binding behavior of the resulting MIPs is evaluated by performing batch rebinding experiments that makes it possible to select the most suitable MIP/non-imprinted polymer couple for future application in aqueous environments. One method to achieve improved compatibility with water is referred to as porogen tuning, in which porogens of varying polarities are used. It is demonstrated that, especially when multiple porogens are mixed, this approach can lead to superior performance in aqueous environments. Another method involves the incorporation of polar or non-polar comonomers in the MIP matrix. It is shown that by carefully selecting these monomers, it is also possible to obtain MIPs, which can selectively bind their target in water.

  5. Government Control of the Media

    OpenAIRE

    Scott Gehlbach; Konstantin Sonin

    2008-01-01

    We present a formal model of government control of the media to illuminate variation in media freedom across countries and over time, with particular application to less democratic states. The extent of media freedom depends critically on two variables: the mobilizing character of the government and the size of the advertising market. Media bias is greater and state ownership of the media more likely when the need for mobilization is large; however, the distinction between state and private m...

  6. Integrating social media in education

    OpenAIRE

    Vanwynsberghe, Hadewijch; Verdegem, Pieter

    2013-01-01

    In their article "Integrating Social Media in Education" Hadewijch Vanwynsberghe and Pieter Verdegem propose a framework in order to integrate social media literacy in an educational setting. In today's networked society students are new media users and hence the relevance in curricula to include social media literacy. Vanwynsberghe and Verdegem propose a multidimensional conceptual framework of social media literacy that includes the practical, cognitive, and affective competencies needed to...

  7. Doing social media analytics

    Directory of Open Access Journals (Sweden)

    Phillip Brooker

    2016-07-01

    Full Text Available In the few years since the advent of ‘Big Data’ research, social media analytics has begun to accumulate studies drawing on social media as a resource and tool for research work. Yet, there has been relatively little attention paid to the development of methodologies for handling this kind of data. The few works that exist in this area often reflect upon the implications of ‘grand’ social science methodological concepts for new social media research (i.e. they focus on general issues such as sampling, data validity, ethics, etc.. By contrast, we advance an abductively oriented methodological suite designed to explore the construction of phenomena played out through social media. To do this, we use a software tool – Chorus – to illustrate a visual analytic approach to data. Informed by visual analytic principles, we posit a two-by-two methodological model of social media analytics, combining two data collection strategies with two analytic modes. We go on to demonstrate each of these four approaches ‘in action’, to help clarify how and why they might be used to address various research questions.

  8. Contemplative Media Studies

    Directory of Open Access Journals (Sweden)

    Kevin Healey

    2015-08-01

    Full Text Available The psychological and socio-economic implications of digital technologies call for scholarship that engages questions about the nature of human consciousness, the construction of the self and the ethics of technical development. In this article, I outline a framework for an approach called contemplative media studies. This approach incorporates several different scholarly threads, namely: via critical political-economic media scholarship, a focus on achieving social and economic justice through policy initiatives and structural reform; via media and religious scholarship, an interest in the religious dimensions of digital culture and the role of media in shaping religious identity; and via contemplative studies, an appreciation of the applicability of contemplative principles to research methods and theory. This framework allows us to examine the spiritual ideology that drives the construction of commercial digital platforms and to ask whether alternative platforms might better catalyze human development. Anchored in a critical commitment to socio-economic justice, contemplative media studies is aimed at articulating an ethically-responsive and economically-sustainable architecture of human flourishing.

  9. From hybrid-media system to hybrid-media politicians

    DEFF Research Database (Denmark)

    Eberholst, Mads Kæmsgaard; Ørsten, Mark; Burkal, Rasmus

    2017-01-01

    An increasingly complex hybrid system of social- and traditional-news media surrounds Nordic election campaigns as politically experienced incumbents favour traditional news media, and younger, lesser-known candidates’ social media. Despite little evidence for hybrid-media politicians, politicians......’ media use is changing rapidly; 15%–16% of Danish candidates used Twitter in 2011 but 68% in 2015. In this large-sample content analysis, party leaders have high traditional-news-media and low Twitter presence, and younger candidates visa-versa, but some politicians have high presence in both. Hybrid...

  10. Internet and Cross Media Productions

    DEFF Research Database (Denmark)

    Petersen, Anja Bechmann

    2006-01-01

    Convergence is one of the hot topics in Internet studies. Recently, however, media organizations have turned their focus to cross media communication. Media organizations are interested in optimizing communication across platforms such as TV, radio, websites, mobile telephones and newspapers....... The aim of this article is to examine the roles of the Internet when emphasis is put on cross media rather than convergence. This article proposes not one unidirectional convergent tendency but manifold roles of the Internet in cross media communication. Inside the media organizations, however......, the Internet continues to play a minor role when compared to older media. The content of the cross media concepts and organizations' history are crucial elements in deciding the priority and use of platforms. Methodologically, the article approaches cross media and the roles of the Internet on a micro...

  11. Internet and Cross Media Productions

    DEFF Research Database (Denmark)

    Petersen, Anja Bechmann

    2006-01-01

    . The aim of this article is to examine the roles of the Internet when emphasis is put on cross media rather than convergence. This article proposes not one unidirectional convergent tendency but manifold roles of the Internet in cross media communication. Inside the media organizations, however......, the Internet continues to play a minor role when compared to older media. The content of the cross media concepts and organizations' history are crucial elements in deciding the priority and use of platforms. Methodologically, the article approaches cross media and the roles of the Internet on a micro......Convergence is one of the hot topics in Internet studies. Recently, however, media organizations have turned their focus to cross media communication. Media organizations are interested in optimizing communication across platforms such as TV, radio, websites, mobile telephones and newspapers...

  12. Media for Reflection

    DEFF Research Database (Denmark)

    Knudsen, Morten

    2016-01-01

    This article develops the concept media for reflection in the interest of conceptualizing the interpretative frames that enable and limit reflection in management and leadership education. The concept ‘media for reflection’ allows us to conceptualize the social and cultural mediation of reflection...... without reducing reflection to an effect of the social structures and cultural norms in which it is embedded. Based on the developed theoretical framework, this article analyses how a renaissance ‘mirror for princes’ and contemporary research-based management education mediate reflection. The content...... of the mediations is analysed as well as the societal and organizational background. Furthermore, the means by which the two media enable and limit reflection in different ways is compared. Finally, the article discusses possible implications of the analysis in terms of management and leadership education....

  13. Social Media Reputation

    DEFF Research Database (Denmark)

    Etter, Michael; Colleoni, Elanor; Ravasi, Davide

    In two ways corporate reputation research has strongly tied corporate actions to stakeholder’s perception of a company and therewith downplayed the autonomy of stakeholder´s evaluation of a firm. First, the most prominent theories used in corporate reputation research tie stakeholder perception...... actions, which demands a greater decoupling of stakeholders´ perceptions from corporate signals or actions in corporate reputation research. We develop the concept of social media reputation as the overall evaluation of a company presented in social media and present a new approach of measuring reputation...... directly to corporate performance and actions. Secondly, prominent reputation measurements couple stakeholders´ believes to reputation drivers through the use of predefined scales and items. We argue that with the rise of social media a company´s reputation has increasingly become autonomous from corporate...

  14. Media and Sexuality

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Carvalho

    2010-03-01

    Full Text Available One of the distinctive marks of current capitalism is the presence of mass media constituting the psyche in different aspects. Today, we observe the multiplication of many contents with erotic appeal in the media and the effects of this process are still to be known, particularly in the matter of sexuality. Concretely, what we have is that the practices and the effective conceptions of sexuality are suffering an accelerated transformation that involves the abandonment of the traditional practices. In this context, we can ask about the sense that is attributed to sexuality experiences and evaluate the impact of the different "manners of being" which are referred to sexuality and systematically diffused by the media. Therefore, we can explore the implications of this new scenery for different social realities: the family institution, the affectionate and loving relationships, the school and professional everyday life, as well as the formulation of public politics in this field.

  15. Media and metamedia management

    CERN Document Server

    Araújo, Xosé; Fernández, Valentín; García, Xosé

    2017-01-01

    Media and Metamedia Management has contributions from seven prestigious experts, who offer their expertise and the view from their vantage point on communication, journalism, advertising, audiovisual, and corporate, political, and digital communication, paying special attention to the role of new technologies, the Internet and social networks, also from an ethics and legal dimension. A total of 118 authors belonging to 31 universities from Spain, Portugal, England and Ecuador have contributed to this book edited, coordinated and introduced by professors Francisco Campos-Freire and Xosé López-García, from the University of Santiago de Compostela, José Rúas-Araújo, from the University of Vigo, and Valentín A. Martínez-Fernández, from the University of A Coruña. Readers may also enjoy 66 articles, grouped into diverse chapters, on Journalism and cyberjournalism, audiovisual sector and media economy, corporate and institutional communication, and new media and metamedia.

  16. SELF-MEDIA

    DEFF Research Database (Denmark)

    Fausing, Bent

    2014-01-01

    The self and identity are not only issues connected to the selfies. They are connected to the development of media since the renaissance; this is the thesis of the following key-note. The subject, the self, is most clearly exposed in the face, and face and identity becomes important in the media...... since the renaissance. The selfies is just the newest development is this tradition, which began with the invention of the mirror, the book (printing), and the miniature painting. They all put the subject as both maker and receiver in the center. This was the birth of the modern subject. The development...... continued throughout the coming centuries. The selfies is the latest invention to discover, explore, visualize and find the self of the subject. The following will therefore naturally focus on the self, the face where the self is most clearly expressed and seen, and the self-media, where the subject can...

  17. Media Challenging Status Quo

    DEFF Research Database (Denmark)

    Sandvik, Kjetil

    Digital media and especially so-called ‘social media’ have on the one hand been ascribed the power to change societies and empower democratic movements following the thoughts of e.g. Rheingold (2004), recently fueled by the democratic uprising in Arabic countries such as Egypt, Tunisia, Iran...... and Libya creating headlines like “the Facebook revolution”. On the other hand, several scholars argue that it is naive to believe that social media in themselves create change: they may at the best facilitate already existing social and political movements (Downing 2008, Christakis & Fowler 2010...... and communication research is currently engaging in a longer and deeper process of examining and assessing the cultural consequences of networked communication. One present challenge is to understand digital media and networked communication at the intersection of established and countercultural, utopian...

  18. Media and ICT

    DEFF Research Database (Denmark)

    Media and information and communication technologies (ICTs) have in the past decades been placed firmly on the educational agenda, and will continue to maintain this position, not least as catalysts for educational change. This issue is reflected in the anthology as it aims to respond....... The multi- and transdisciplinary perspective is reflected in the learning theories of the articles, which are based on constructivist, situated and systems theories that in various ways relate to shared knowledge, workplace learning, collaborative learning and virtual learning communities....... to the question of how the presence of media and ICT in and outside schools both change and qualify educational practice as well as how the cooperation between media, cultures, aesthetics and social relations affect and support new demands on education. The book represents different academic perspectives...

  19. Open Media Training Session

    CERN Document Server

    CERN. Geneva; Marchant, Nadia

    2010-01-01

    Have you ever wondered how the media work and why some topics make it into the news and other don't? Would you like to know how to (and how not to) give an interview to a journalist? With the LHC preparing for first collisions at high energies, the world's media are again turning their attention to CERN. We're all likely to be called upon to explain what is happening at CERN to media, friends and neighbours. The seminar will be given by BBC television news journalists Liz Pike and Nadia Marchant, and will deal with the kind of questions we're likely to be confronted with through the restart period. Follow the webcast: http://webcast.cern.ch/

  20. Modern Media Phenomenon

    Directory of Open Access Journals (Sweden)

    Erika Prijatelj

    2011-09-01

    Full Text Available Contemporary media culture is de fi ned by the logic of the victorious spectacle expanding to all areas of life. Post-modern capitalism has turned everyday life and culture into entertainment with the help of the spectacular. In fact, such entertainment results in a fake sense of happiness, pop mainstream, the swallowing up alternatives and therefore the creation of a passive consumer society. The media today have a unique power of overwhelming a person with information. They enable a modern person to know much, but understand little. This discussion has cast some light on very popular reality shows, the body and sports. It concludes with a re fl ection on modern media, which leave a person of this age with a patchwork identity.

  1. Corporeal-Locomotive Media

    DEFF Research Database (Denmark)

    Nørgård, Rikke Toft

    activities and experiences across the abovementioned gameworlds. As a consequence, the article points towards the centrality of expressive first-person corporeality and locomotion in digital games – a circumstance that sets the practice and experience of digital games apart from media practices...... and experiences such as reading or listening to a story and watching a movie or theatre play and other traditional or new media forms. These circumstances make the article question whether digital games can be understood as (new) media form at all and, thus, it points towards a possible new vocabulary...... and structure’ of a couple of specific interactions, expressions and experiences that in the study have proven to be characteristic of being a gameplayer in gameplay in digital games – regardless of whether you are a child playing Temple Run 2 or Frut Ninja on the iPhone, a tween playing Battlefield 3 on your...

  2. Death in media

    Directory of Open Access Journals (Sweden)

    Pavićević Aleksandra

    2010-01-01

    Full Text Available This paper discusses the role of media in a construction of public image speech and presentation of death. The main research questions could be posed as follows: does the media discourse confirm a thesis about modern society as the one which intensely avoids encounter with Death, or does it defy it? Frequent images or hints of death in visual media in films informative and entertainment programs-suggest certain changes related to this issue in the past few decades. This analysis focuses on printed media hence the paper assesses numerous issues of the daily journal Politika from 1963, 1972, 1973, 1979, 1985, 1991, 1995, 1999, 2007 and 2008, as well as some other daily journals after 2000. The analysis confirms a strong connection between the current political systems and ideology and speech about death. In addition, it reveals a political usage of this event but also speaks up about cultural and historical models, underlying all other constructions. During the 1960's and 1970's, the presentations, including the speech about death relied on the traditional understandings about inevitability of death and dying, and alternatively on atheistic beliefs related to the progress and wellbeing of the society. In this particular discourse, death was present to a limited degree, serving primarily to glorify socialist order. The end of the 1970's witnessed an increase in the glorification of the death, correlated with the decrease of the dominant political ideology. On the other hand, the 1990's brought about more presence of the national and religious symbolism and glorification of the dead as heroes. After 2000, mercantilism is evident throughout the media. All of the media broadcast drastic images of death and dead, thus providing an answer to the posed question at the beginning of this paper about the relationship of the modern society towards death but nevertheless, this still leaves out many implicit consequences and possible meanings.

  3. A HIGH SENSITIVE MICROWAVE MEASURING DEVICE OF THE MOISTURE CONTENT IN THE NON-POLAR DIELECTRIC LIQUIDS BASED ON AN INHOMOGENEOUS STEP COAXIAL RESONATOR

    Directory of Open Access Journals (Sweden)

    V. V. Rudakov

    2016-11-01

    Full Text Available Purpose. Objective is to create a moisture meter for non-polar liquid dielectrics with low volumetric moisture content of more than 10‑3 %. Methodology. Moisture measuring is based on dielcometric method. It is implemented as a resonant method of determining a capacitance measuring transducer. Measuring transducer capacitive type has a working and parasitic capacitance. It was suggested the definition of moisture on four of resonance frequencies: when the measuring transducer is turned off, one by one filled with air, «dry» and investigated liquid, to determine the parasitic capacitance of the measuring generator, and the parasitic capacitance of the measuring transducer and humidity. Measurement frequency was increased up to microwave range to increase the sensitivity. Measuring transducer with distributed parameters representing a step heterogeneous coaxial resonator is used by. This measuring transducer has a zero stray capacitance, because the potential electrode has a galvanic connection with an external coaxial electrode. Inductive ties loop is used to neglect parasitic capacitance of the measuring generator, and to increase the quality factor of the system. Measuring moisture is reduced to measuring the two frequencies of resonance frequency and «dry» and investigated liquid. Resonant characteristics transducer in a step inhomogeneous coaxial resonator have been investigated to determine the quality factor of filled with air and transformer oil, and experiments to measure the moisture content in transformer oil have been conducted. Results. Measuring transducer of distributed type is developed and researched – it is step inhomogeneous coaxial resonator. It has a smaller geometric length and larger scatter of the first and second resonant frequencies. Expression is obtained for determination of moisture on the basis of two resonant frequencies. The formula of the two frequencies to determine the moisture is correct. Resonant

  4. HTML5 Media

    CERN Document Server

    Powers, Shelley

    2011-01-01

    If you're a web developer or designer familiar with CSS and JavaScript, this tightly focused introduction shows you how to add HTML5 media elements to your web pages, and how to provide custom controls for letting web visitors interact with the content. You'll also learn how to provide subtitles and captions, using file formats that work in browsers now. This book includes code samples and downloadable examples to help you take full advantage of audio and video in your web pages. Ensure your audio or video works in all browsers that support HTML5 media elementsLearn about widely supported me

  5. Strategy and New Media

    DEFF Research Database (Denmark)

    Plesner, Ursula; Gulbrandsen, Ib Tunby

    2015-01-01

    Despite current attention to the materiality of organizations and the performative role of tools, devices, artefacts and objects in processes of strategy-making, the impact of new media has not been thoroughly conceptualized in the strategy literature. We argue that new media challenge core...... assumptions in strategy about control, boundaries and choice. To understand their constitutive effects and the implications for strategy-making, it is necessary to develop a research agenda oriented towards understanding technological affordances – but not only in local practices. Due to vital characteristics...

  6. Smartphones as locative media

    CERN Document Server

    Frith, Jordan

    2015-01-01

    Smartphone adoption has surpassed 50% of the population in more than 15 countries, and there are now more than one million mobile applications people can download to their phones. Many of these applications take advantage of smartphones as locative media, which is what allows smartphones to be located in physical space. Applications that take advantage of people's location are called location-based services, and they are the focus of this book. Smartphones as locative media raise important questions about how we understand the complicated relationship between the Internet and physical space

  7. Multisided Media Markets

    DEFF Research Database (Denmark)

    Lindstädt, Nadine

    Media markets recently have been identified as multisided markets. The application of the theory of multisided markets provides a better understanding of such markets. It enriched the hitherto economic approach and led to new insights and perspectives especially for the antitrust authorities when...... evaluating competition constraints and mergers. This paper reviews the theory of multisided markets and subsequently applies it to media markets. Finally the paper draws attention to the new perspectives and insights the theory provides but also brings open research questions to light....

  8. Biorelevant dissolution media

    DEFF Research Database (Denmark)

    Ilardia-Arana, David; Kristensen, Henning G; Müllertz, Anette

    2006-01-01

    Biorelevant dissolution media containing bile salt and lecithin at concentrations appropriate for fed and fasted state are useful when testing oral solid formulations of poorly water-soluble drugs. Dilution of amphiphile solutions affects the aggregation state of the amphiphiles because bile salt....... Dilution of the two- and four component media caused enlargement of the mixed micelles and formation of vesicles. The solubility of estradiol in the buffer solution was increased with addition of the amphiphiles. A good correlation (R(2) = 0.987) was found between estradiol solubility and mass...

  9. Multisided Media Markets

    DEFF Research Database (Denmark)

    Lindstädt, Nadine

    Media markets recently have been identified as multisided markets. The application of the theory of multisided markets provides a better understanding of such markets. It enriched the hitherto economic approach and led to new insights and perspectives especially for the antitrust authorities when...... evaluating competition constraints and mergers. This paper reviews the theory of multisided markets and subsequently applies it to media markets. Finally the paper draws attention to the new perspectives and insights the theory provides but also brings open research questions to light....

  10. Acute otitis media.

    Science.gov (United States)

    Dickson, Gretchen

    2014-03-01

    One in 4 children will have at least 1 episode of acute otitis media (AOM) by age 10 years. AOM results from infection of fluid that has become trapped in the middle ear. The bacteria that most often cause AOM are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Differentiating AOM from otitis media with effusion (OME) is a critical skill for physicians, as accurate diagnosis will guide appropriate treatment of these conditions. Although fluid is present in the middle ear in both conditions, the fluid is not infected in OME as is seen in AOM patients.

  11. Mobile Media Photography

    DEFF Research Database (Denmark)

    Svabo, Connie; Shanks, Michael

    2013-01-01

    Mobile media photography marks a shift in orientation from the image towards photography as a mode of engagement. This leads is to explore the processes of experience and documentation that mobile media help to constitute. We unfold two aspects of the process of photography: photography as temporal......, archaeological engagement, and photography as spatial, geographical engagement. Finally, as a closing perspective we point out that vernacular photography may be read as an intersection between a personal means of expression and corporate financial interest....

  12. Social Media and Marketing

    OpenAIRE

    Jaffrey, Jarrar

    2011-01-01

    During different time era’s different methods of communications has developed and changed the everyday life. Social media has become the way of communication in the 21st-century, enabling us to express our thoughts, ideas and feelings in a complete new way. This way of communication have also had a huge impact on corporations, where they have realized that without a proper plan and social media strategy they have no chance to stand out in the rapidly changing digital space. To ensure a succes...

  13. Hypertextuality and Social Media

    DEFF Research Database (Denmark)

    Albu, Oana Brindusa; Etter, Michael

    2016-01-01

    Texts and conversations are central to the constitution of organizations. Through the use of social media technologies, organizational members and nonorganizational members alike have the capacity to author organizational texts that co-constitute an organization as an entity with a specific...... identity in a situational space and time. The implications of this ability are underexplored. This study focused on how two organizations used the social media technology Twitter to interact with their constituents. The article adopts communication-centered and sociomateriality perspectives to illustrate...

  14. TAXATION OF SOCIAL MEDIA ADVERTISEMENTS

    Directory of Open Access Journals (Sweden)

    F. Rifat ORTAÇ

    2016-01-01

    Full Text Available Today, the use of Internet and in particular social media as advertising tools brings the question of how the advertisement in social media should be taxed. This is not only seen as a problem in our country, but in the international platform as well. In the first part of the study, the definition of social media is given; in the second part, Social Media Brand Communities and Fun Pages are discussed; in the third part, a comparison of Social Media Con- tents and Public Goods, Global Public Goods and Club Goods is made; in the fourth part that Conclusion and Suggestions how social media is taxed is discussed.

  15. Media Philosophy— A Reasonable Programme?

    OpenAIRE

    Schmidt, Siegfried J

    2008-01-01

    It is beyond any doubt that media have an enormous impact on our media-culture societies. Media in?uence our perception and our knowledge, our memory as well as our emotions. They create public spheres and public opinions and give rise to media realities. Media shape our socialisation and our communality. They transform economy, politics, science, religion and law. “What we know about our society, even about our world we are living in, we know via the mass media.” (Luhmann 1996:9; my translat...

  16. Defending Whose Democracy?\\ud Media Freedom and Media Power

    OpenAIRE

    Fenton, Natalie

    2014-01-01

    Rarely has the relationship between media and democracy been so centre-stage. Whether regarding regulatory reform brought about by phone hacking in the UK, concentration of media ownership in Italy, Hungary, Australia to mention but a few; or in relation to social media and the internet as a supposed means to increased access to information and citizen production and circulation of non-mainstream content leading to greater so called media freedom. The debate on whether or not and in what form...

  17. More Media, More People—On Social & Multimodal Media Intelligence

    OpenAIRE

    Degerstedt, Lars; Pelle, Snickars

    2017-01-01

    The purpose of this article is to address some challenges facing media intelligence in general, and competitive intelligence in particular within an altered information landscape. To understand this new situation, the notion of social and multimodal media intelligence are introduced. With cases taken primarily from the Swedish media intelligence sector, we argue that data driven media intelligence today needs to pay increasing attention to new forms of (A.) crowd-oriented and (B.) multimedia-...

  18. Islam and Media Representations

    Directory of Open Access Journals (Sweden)

    Mohamed Bensalah

    2006-04-01

    Full Text Available For the author of this article, the media’s treatment of Islam has raised numerous polymorphous questions and debates. Reactivated by the great scares of current events, the issue, though an ancient one, calls many things into question. By way of introduction, the author tries to analyse the complex processes of elaboration and perception of the representations that have prevailed during the past century. In referring to the semantic decoding of the abundant colonial literature and iconography, the author strives to translate the extreme xenophobic tensions and the identity crystallisations associated with the current media orchestration of Islam, both in theWest and the East. He then evokes the excesses of the media that are found at the origin of many amalgams wisely maintained between Islam, Islamism and Islamic terrorism, underscoring their duplicity and their willingness to put themselves, consciously, in service to deceivers and directors of awareness, who are very active at the heart of the politico-media sphere. After levelling a severe accusation against the harmful drifts of the media, especially in times of crisis and war, the author concludes by asserting that these tools of communication, once they are freed of their masks and invective apparatuses, can be re-appropriated by new words and bya true communication between peoples and cultures.

  19. Media, Place, and Multiculturalism.

    Science.gov (United States)

    Meyrowitz, Joshua; Maguire, John

    1993-01-01

    Explores the role of television in American culture. America may be more diverse than ever in race, ethnicity, and religion, but, because of mass media, there is less diversity in experience, perspectives, and expectation. Subcultures that once manifested existence locally now look to television for verification of their existence. (SLD)

  20. Corruption in the Media.

    NARCIS (Netherlands)

    Spence, E.H.

    2009-01-01

    Using a general model of corruption that explains and accounts for corruption across different corporate and professional activities, the paper will examine how certain practices in the media, especially in areas where journalism, advertising and public relations regularly intersect and converge,

  1. The Indian Media Scenario.

    Science.gov (United States)

    Eapen, K. E.

    As background information for a discussion of India's communication system and its potential for social change, this paper briefly describes the country's physical characteristics, some of its cultural heritage and demographics, and the development of its education and railways. After a discussion of the folk media (traditional changes) of…

  2. Photochemistry in Organized Media.

    Science.gov (United States)

    Fendler, Janos H.

    1983-01-01

    Describes common artificially produced organized media such as colloids, surfactants, and polymers and their usefulness in studying complex biochemical processes. Discusses selected recent photophysical and photochemical exploitations of these systems, including artificial photosynthesis, in situ generation of colloidal gold and platinum,…

  3. Femicide in media

    Directory of Open Access Journals (Sweden)

    Mršević Zorica

    2014-01-01

    Full Text Available Media in Serbia explain femicide usually as caused by poverty and alcoholism. This style is gender blind and socially stereotyped because of neglected gender aspects of male violence against women. Particular problem is lack of problematizing obvious social “permission” of male violence. Femicide is regularly presented as an incident, allegedly impossible for anticipation rather than tragic epilogue of long lasting male violence against women which as such exists as a part of traditional gender social relations and roles. Media overlook that alcohol and poverty may only contribute to intensification of already existing, widely accepted domination of men and subordination of women. Media reports as a rule didn’t enter deeper into problems of institutional and social context in which is perpetrated long lasting violence as prefacing femicide. Media also never criticize the social behavior of neighbors, relatives and all others informed on the domestic violence, but rather avoid „mixing“into privacy matters. Thus violence escalates without barriers, eventually developed in femicide, murder a woman, victim of this, decades long lasting violence.

  4. Digital media ethics

    DEFF Research Database (Denmark)

    Ess, Charles

    Designed as both a teaching text and reader for students and faculty across diverse disciplines, the book provides an "ethical toolkit" - an introduction to prevailing ethical frameworks - and shows their application to both general issues and specific case-studies in digital media (privacy...

  5. Waves in inhomogeneous media

    NARCIS (Netherlands)

    Gerritsen, S.

    2007-01-01

    In this thesis we study wave propagation in inhomogeneous media. Examples of the classical (massless) waves we consider are acoustic waves (sound) and electromagnetic waves (light, for example). Interaction with inhomogeneities embedded in a reference medium alter the propagation direction, velocity

  6. Media for Multicultural Education.

    Science.gov (United States)

    Maestro-Scherer, Jane B.; And Others

    1979-01-01

    A cross-cultural course sequence at Iowa State University which offers a Third World cultural experience and introduces students to Third World views about such crucial world problems as population pressures, food supplies, and energy resources has a continuing need for media resources, e.g., films and slides. (CMV)

  7. Motivation for media training

    Directory of Open Access Journals (Sweden)

    Anita Mikulič

    2008-12-01

    Full Text Available Readers have been reading more than only texts in books, magazines, newspapers, but also texts in films and TV screens, mobile phones and similar. Moreover, at present we’ve been surrounded by images, which we have yet to learn to read, judge critically and use as a form of articulation. This article, thus, presents useful suggestions for media training.

  8. Expanding Media Reach

    Centers for Disease Control (CDC) Podcasts

    2007-11-01

    In this podcast, two nurses serving a Chinese American community show how they have used local ethnic media to communicate health messages.  Created: 11/1/2007 by National Diabetes Education Program (NDEP), a joint program of the Centers for Disease Control and Prevention and the National Institutes of Health.   Date Released: 11/11/2007.

  9. Mass Media and Society.

    Science.gov (United States)

    Wells, Alan

    Designed to serve as a basic text for general liberal arts courses in mass communication, this book presents essays, largely from recent magazine articles, written from the layman (although there are a few more overtly scholarly articles). It begins with an examination of the media industries in the United States, treating them as complex…

  10. The Media Works.

    Science.gov (United States)

    Valdes, Joan; Crow, Jeanne

    This student text and activity book provides information on and suggests ways to examine seven of the mass media: movies, television, advertising, magazines, comics, radio, and newspapers. Much of the learning takes place by actual examination of actual products to learn characteristics common to them. The first section investigates the process of…

  11. Cyberbullying via Social Media

    Science.gov (United States)

    Whittaker, Elizabeth; Kowalski, Robin M.

    2015-01-01

    Recent years have witnessed a surge of research on cyberbullying. In this article, three studies examined prevalence rates of cyberbullying among college-age students, venues through which cyberbullying occurs, with a particular focus on social media, and perceptions of cyberbullying as a function of features of the target (e.g., peer, celebrity,…

  12. Corruption in the Media

    NARCIS (Netherlands)

    Spence, Edward H.

    2009-01-01

    Using a general model of corruption that explains and accounts for corruption across different corporate and professional activities, the paper will examine how certain practices in the media, especially in areas where journalism, advertising and public relations regularly intersect and converge, ca

  13. Cyberbullying via Social Media

    Science.gov (United States)

    Whittaker, Elizabeth; Kowalski, Robin M.

    2015-01-01

    Recent years have witnessed a surge of research on cyberbullying. In this article, three studies examined prevalence rates of cyberbullying among college-age students, venues through which cyberbullying occurs, with a particular focus on social media, and perceptions of cyberbullying as a function of features of the target (e.g., peer, celebrity,…

  14. In medias res

    DEFF Research Database (Denmark)

    Foote, Jonathan

    2017-01-01

    nor does he begin the Trojan War ab ovo (with the egg) but always he hurries to the action and snatches the listener in medias res (into the middle of things)      Horace, Ars Poetica 145–147 Good epic poets do not commence their tale from the beginning—ab ovo (with the egg)—as Horace states...

  15. Ethics and media

    Directory of Open Access Journals (Sweden)

    Freddy Álvarez

    2008-06-01

    Full Text Available Preguntarse por la ética y los Mass Media,no es fácil. Es una interpelación impregnada de complejidad por la pluralidad de los Media, unida a la dificultad para entender un fenómeno relativamente actual. Además, para lograr acercarnos a una repuesta seria y profunda es importante replantear la ética de otro modo. Los Media, en tanto que tecnologías, como todas las ciencias, debido a la influencia del cartesianismo, han estado fuera de toda relación ética. Quienes los manejan, todavía creen que por pretender a la objetividad y a la neutralidad ya están en la ética. Veamos un poco las derivas en las que ingresan los Media a causa de su disyunción con la ética y los grandes olvidos en los que ha caído, sobre todo en lo que se refiere a la ética y a la verdad.

  16. Big Data, Small Media

    Directory of Open Access Journals (Sweden)

    Grant Bollmer

    2014-08-01

    Andrew Dubber Radio in the Digital Age Polity, Cambridge, 2013   Charles Ess Digital Media Ethics, Second Edition Polity, Cambridge, 2014   Graeme Kirkpatrick Computer Games and the Social Imaginary Polity, Cambridge, 2013   Dhiraj Murthy Twitter: Social Communication in the Twitter Age Polity, Cambrige, 2013   Jill Walker Rettberg Blogging, Second Edition Polity, Cambridge, 2014

  17. Library Media Services Handbook.

    Science.gov (United States)

    Winnipeg School Div. Number 1, Manitoba (Canada).

    This 1991 edition of the handbook for Winnipeg School Division Number 1 school library media programs presents detailed program guidelines, objectives, philosophies, and goals in five major sections: (1) Library Policy and Practices (statement of the division's educational philosophy and goals, philosophy and goals of the division's library…

  18. European media law

    NARCIS (Netherlands)

    Castendyk, O.; Dommering, E.; Scheuer, A.

    2008-01-01

    European Union legislation concerning electronic communications media is firmly established as an essential part of the law in the field in Europe. From relevant provisions of the European Convention of Human Rights and the EC Treaty to numerous directives, the most recent being the Audiovisual Medi

  19. Waves in inhomogeneous media

    NARCIS (Netherlands)

    Gerritsen, S.

    2007-01-01

    In this thesis we study wave propagation in inhomogeneous media. Examples of the classical (massless) waves we consider are acoustic waves (sound) and electromagnetic waves (light, for example). Interaction with inhomogeneities embedded in a reference medium alter the propagation direction, velocity

  20. Media for Enterobacteriaceae

    NARCIS (Netherlands)

    Mossel, D.A.A.

    1985-01-01

    The ‘rag-bag character of ‘coli-aerogenes’ bacteria used originally as markers for process failure has prompted their substitution by the taxonomically accurately delineated group of Enterobacteriaceae. Media previously used for the detection or enumeration of the coli-aerogenes group can be adapted

  1. Media challenging capitalism

    DEFF Research Database (Denmark)

    Sandvik, Kjetil

    Digital media and especially so-called ‘social media’ have on the one hand been ascribed the power to change societies and empower democratic movements following the thoughts of e.g. Rheingold (2004), recently fueled by the democratic uprising in Arabic countries such as Egypt, Tunisia, Iran and ...

  2. Media challenging capitalism

    DEFF Research Database (Denmark)

    Sandvik, Kjetil

    Digital media and especially so-called ‘social media’ have on the one hand been ascribed the power to change societies and empower democratic movements following the thoughts of e.g. Rheingold (2004), recently fueled by the democratic uprising in Arabic countries such as Egypt, Tunisia, Iran and ...

  3. Division Level Social Media

    Science.gov (United States)

    2015-06-12

    also enabled news to travel faster than it has in the past. An example would be the same person living in Dubai watching the documentary or news...completely free for divisional units. Unlike a personal social media page, which is updated and checked at a person’s leisure or a spare moment during the

  4. Media, geschiedenis en representatie

    NARCIS (Netherlands)

    Vree, Frank van

    1998-01-01

    textabstractA short introduction to the concept 'representation'. In the broadest sense, 'representation' can be defined as a presentation loaded with meaning. As an analytical concept, 'representation' can be extraordinarily fruitful in the practice of media history. Films, photos, television

  5. News Media Industry

    Science.gov (United States)

    2006-01-01

    transform the way Americans receive news and information. But Saul Hansell of the New York Times believes none of this is a surprise to the media elites...References Anderson, B. (2004). “News Flash: Journalism, Infotainment and the Bottom-Line Business of Broadcast News.” Jossey- Bass , pp

  6. Media Now: A Historical Review of a Media Literacy Curriculum

    Science.gov (United States)

    Friesem, Yonty; Quaglia, Diane; Crane, Ed

    2014-01-01

    The Elizabeth Thoman Archive at the Harrington School of Communication and Media, University of Rhode Island, has the last complete kit of one of the milestones in the early chronology of media literacy, the 1972 Media Now curriculum. This curriculum was the first of its kind, using self-contained lesson modules that were part of a larger series…

  7. Cathodoluminescence study of Mg activation in non-polar and semi-polar faces of undoped/Mg-doped GaN core-shell nanorods

    Science.gov (United States)

    Hortelano, V.; Martínez, O.; Cuscó, R.; Artús, L.; Jiménez, J.

    2016-03-01

    Spectrally and spatially resolved cathodoluminescence (CL) measurements were carried out at 80 K on undoped/Mg-doped GaN core-shell nanorods grown by selective area growth metalorganic vapor phase epitaxy in order to investigate locally the optical activity of the Mg dopants. A study of the luminescence emission distribution over the different regions of the nanorods is presented. We have investigated the CL fingerprints of the Mg incorporation into the non-polar lateral prismatic facets and the semi-polar facets of the pyramidal tips. The amount of Mg incorporation/activation was varied by using several Mg/Ga flow ratios and post-growth annealing treatment. For lower Mg/Ga flow ratios, the annealed nanorods clearly display a donor-acceptor pair band emission peaking at 3.26-3.27 eV and up to 4 LO phonon replicas, which can be considered as a reliable indicator of effective p-type Mg doping in the nanorod shell. For higher Mg/Ga flow ratios, a substantial enhancement of the yellow luminescence emission as well as several emission subbands are observed, which suggests an increase of disorder and the presence of defects as a consequence of the excess Mg doping.

  8. B3LYP periodic study of the physicochemical properties of the nonpolar (010) Mg-pure and fe-containing olivine surfaces.

    Science.gov (United States)

    Navarro-Ruiz, Javier; Ugliengo, Piero; Rimola, Albert; Sodupe, Mariona

    2014-08-07

    B3LYP periodic simulations have been carried out to study some physicochemical properties of the bulk structures and the corresponding nonpolar (010) surfaces of Mg-pure and Fe-containing olivine systems; i.e., Mg2SiO4 (Fo) and Mg1.5Fe0.5SiO4 (Fo75). A detailed structural analysis of the (010) Fo and Fo75 surface models shows the presence of coordinatively unsaturated metal cations (Mg(2+) and Fe(2+), respectively) with shorter metal-O distances compared to the bulk ones. Energetic analysis devoted to the Fe(2+) electronic spin configuration and to the ion position in the surfaces reveals that Fe(2+) in its quintet state and placed at the outermost positions of the slab constitutes the most stable Fe-containing surface, which is related to the higher stability of high spin states when Fe(2+) is coordinatively unsaturated. Comparison of the simulated IR and the corresponding reflectance spectra indicates that Fe(2+) substitution induces an overall bathochromic shift of the spectra due to the larger mass of Fe compared to Mg cation. In contrast, the IR spectra of the surfaces are shifted to upper values and exhibit more bands compared to the corresponding bulk systems due to the shorter metal-O distances given in the coordinatively unsaturated metals and to symmetry reduction which brings nonequivalent motions between the outermost and the internal modes, respectively.

  9. Groove-type channel enhancement-mode AlGaN/GaN MIS HEMT with combined polar and nonpolar AlGaN/GaN heterostructures

    Science.gov (United States)

    Duan, Xiao-Ling; Zhang, Jin-Cheng; Xiao, Ming; Zhao, Yi; Ning, Jing; Hao, Yue

    2016-08-01

    A novel groove-type channel enhancement-mode AlGaN/GaN MIS high electron mobility transistor (GTCE-HEMT) with a combined polar and nonpolar AlGaN/GaN heterostucture is presented. The device simulation shows a threshold voltage of 1.24 V, peak transconductance of 182 mS/mm, and subthreshold slope of 85 mV/dec, which are obtained by adjusting the device parameters. Interestingly, it is possible to control the threshold voltage accurately without precisely controlling the etching depth in fabrication by adopting this structure. Besides, the breakdown voltage (V B) is significantly increased by 78% in comparison with the value of the conventional MIS-HEMT. Moreover, the fabrication process of the novel device is entirely compatible with that of the conventional depletion-mode (D-mode) polar AlGaN/GaN HEMT. It presents a promising way to realize the switch application and the E/D-mode logic circuits. Project supported by the National Science and Technology Major Project, China (Grant No. 2013ZX02308-002) and the National Natural Science Foundation of China (Grant Nos. 11435010, 61474086, and 61404099).

  10. Structural and optical investigation of nonpolar a-plane GaN grown by metal-organic chemical vapour deposition on r-plane sapphire by neutron irradiation

    Institute of Scientific and Technical Information of China (English)

    Xu Sheng-Rui; Zhang Jin-Feng; Gu Wen-Ping; Hao Yue; Zhang Jin-Cheng; Zhou Xiao-Wei; Lin Zhi-Yu; Mao Wei

    2012-01-01

    Nonpolar (11(2)0) a-plane GaN films are grown by metal-organic chemical vapour deposition (MOCVD) on r-plane (1(1)02) sapphire.The samples are irradiated with neutrons under a dose of 1 × 1015 cm-2.The surface morphology,the crystal defects and the optical properties of the samples before and after irradiation are analysed using atomic force microscopy (AFM),high resolution X-ray diffraction (HRXRD) and photoluminescence (PL).The AFM result shows deteriorated sample surface after the irradiation.Careful fitting of the XRD rocking curve is carried out to obtain the Lorentzian weight fraction.Broadening due to Lorentzian type is more obvious in the as-grown sample compared with that of the irradiated sample,indicating that more point defects appear in the irradiated sample.The variations of line width and intensity of the PL band edge emission peak are consistent with the XRD results.The activation energy decreases from 82.5 meV to 29.9 meV after irradiation by neutron.

  11. Identifying important structural features of ionic liquid stationary phases for the selective separation of nonpolar analytes by comprehensive two-dimensional gas chromatography.

    Science.gov (United States)

    Zhang, Cheng; Ingram, Isaiah C; Hantao, Leandro W; Anderson, Jared L

    2015-03-20

    A series of dicationic ionic liquid (IL)-based stationary phases were evaluated as secondary columns in comprehensive two-dimensional gas chromatography (GC×GC) for the separation of aliphatic hydrocarbons from kerosene. In order to understand the role that structural features of ILs play on the selectivity of nonpolar analytes, the solvation parameter model was used to probe the solvation properties of the IL-based stationary phases. It was observed that room temperature ILs containing long free alkyl side chain substituents and long linker chains between the two cations possess less cohesive forces and exhibited the highest resolution of aliphatic hydrocarbons. The anion component of the IL did not contribute significantly to the overall separation, as similar selectivities toward aliphatic hydrocarbons were observed when examining ILs with identical cations and different anions. In an attempt to further examine the separation capabilities of the IL-based GC stationary phases, columns of the best performing stationary phases were prepared with higher film thickness and resulted in enhanced selectivity of aliphatic hydrocarbons.

  12. The solution properties of mefenamic acid and a closely related analogue are indistinguishable in polar solvents but significantly different in nonpolar environments.

    Science.gov (United States)

    Lee, Eun Hee; Byrn, Stephen R; Pinal, Rodolfo

    2012-12-01

    This study investigates the cosolute effects of mefenamic acid (XA) and flufenamic acid (FA). These compounds serve as model of a drug discovery lead compound and a structural analogue. The activity coefficients of XA and FA in different solvents were obtained from solubility measurements at 25°C. The effect of varying concentrations of FA on the solubility of XA in four different solvents, including toluene, cyclohexane, ethanol, and an ethanol-water mixture (80:20, v/v), was investigated. The magnitude of change in the activity coefficient of XA in the presence of FA in different solvents was used to elucidate the thermodynamic effect of FA on the solubility of XA. Nuclear magnetic resonance and Fourier-transform infrared spectroscopy were used to obtain molecular level information about the interactions of the compounds in solution. The presence of FA increases XA solubility in toluene and in cyclohexane as much as seven-fold. Conversely, in ethanol and the ethanol-water mixture, similar levels of FA have essentially no effect on the solubility of XA. The solution properties investigated show that despite the close structural similarity between XA and FA, the two compounds are strongly distinguishable in nonpolar solvents. Conversely, the solution properties of the same two solutes are indistinguishable in polar solvents. A solubilization model based on solute-cosolute interactions is presented.

  13. Uptake calibration of polymer-based passive samplers for monitoring priority and emerging organic non-polar pollutants in WWTP effluents.

    Science.gov (United States)

    Posada-Ureta, Oscar; Olivares, Maitane; Zatón, Leire; Delgado, Alejandra; Prieto, Ailette; Vallejo, Asier; Paschke, Albrecht; Etxebarria, Nestor

    2016-05-01

    The uptake calibration of more than 12 non-polar organic contaminants by 3 polymeric materials is shown: bare polydimetilsiloxane (PDMS, stir-bars), polyethersulfone tubes and membranes (PES) and polyoxymethylene membranes (POM), both in their free form and membrane-enclosed sorptive coating (MESCO). The calibration process was carried out exposing the samplers to a continuous flow of contaminated water at 100 ng mL(-1) for up to 28 days, and, consequently, the sampling rates (Rs, mL day(-1)) of several organic microcontaminants were provided for the first time. In situ Rs values were also determined disposing the samplers in the effluent of a wastewater treatment plant. Finally, these passive samplers were applied to monitor the effluents of two wastewater treatment plants. This application lead to the confirmation of the presence of galaxolide, tonalide and 4-tert-octylphenol at high ng mL(-1) levels, as well as the identification of compounds like some phthalates and alkylphenols at levels below the detection limits for active sampling methods.

  14. Nonpolar resistive memory switching with all four possible resistive switching modes in amorphous LaHoO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Yogesh; Pavunny, Shojan P.; Katiyar, Ram S., E-mail: rkatiyar@hpcf.upr.edu [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00936-8377 (United States); Fachini, Esteban [General Studies College, University of Puerto Rico, San Juan, Puerto Rico 00931 (United States); Scott, James F. [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB0 3HE (United Kingdom)

    2015-09-07

    We studied the resistive memory switching in pulsed laser deposited amorphous LaHoO{sub 3} (a-LHO) thin films for non-volatile resistive random access memory applications. Nonpolar resistive switching (RS) was achieved in Pt/a-LHO/Pt memory cells with all four possible RS modes (i.e., positive unipolar, positive bipolar, negative unipolar, and negative bipolar) having high R{sub ON}/R{sub OFF} ratios (in the range of ∼10{sup 4}–10{sup 5}) and non-overlapping switching voltages (set voltage, V{sub ON} ∼ ±3.6–4.2 V and reset voltage, V{sub OFF} ∼ ±1.3–1.6 V) with a small variation of about ±5–8%. Temperature dependent current-voltage (I–V) characteristics indicated the metallic conduction in low resistance states (LRS). We believe that the formation (set) and rupture (reset) of mixed conducting filaments formed out of oxygen vacancies and metallic Ho atoms could be responsible for the change in the resistance states of the memory cell. Detailed analysis of I–V characteristics further corroborated the formation of conductive nanofilaments based on metal-like (Ohmic) conduction in LRS. Simmons-Schottky emission was found to be the dominant charge transport mechanism in the high resistance state.

  15. Giant tunneling electroresistance induced by ferroelectrically switchable two-dimensional electron gas at nonpolar BaTiO3/SrTiO3 interface

    Science.gov (United States)

    Wu, Qingyun; Shen, Lei; Yang, Ming; Zhou, Jun; Chen, Jingsheng; Feng, Yuan Ping

    2016-10-01

    Using first-principles calculations, we investigate the tunneling electroresistance (TER) of ferroelectric tunnel junctions [Pt /BaTiO3(BTO)/SrTiO3(STO )/Pt ]. It is found that the TER of Pt/BTO/STO/Pt junctions can be greatly increased with increasing thickness of STO layers. The underlying physics of this giant TER is the switchable two-dimensional electron gas (2DEG) at a nonpolar BTO/STO interface induced by the ferroelectric polarization. Our calculations show that when the ferroelectric polarization is pointing from BTO to STO, a 2DEG forms at the interface and acts as bridge for electrons to tunnel through the junctions. Nevertheless, there is no 2DEG at the interface under the opposite direction of the ferroelectric polarization, which results in a large tunnel resistance. More importantly, this ferroelectrically switchable 2DEG leads to a low resistance area product for Pt/BTO/STO/Pt junctions, which offers good compatibility with other components in an integrated circuit and is highly desired for industrial applications.

  16. Molecular dynamics analysis of the friction between a water-methanol liquid mixture and a non-polar solid crystal surface

    Science.gov (United States)

    Nakaoka, Satoshi; Yamaguchi, Yasutaka; Omori, Takeshi; Joly, Laurent

    2017-05-01

    We performed molecular dynamics analysis of the momentum transfer at the solid-liquid interface for a water-methanol liquid mixture between parallel non-polar solid walls in order to understand the strong decrease of the friction coefficient (FC) induced by the methanol adsorption at the surface observed in our previous work [S. Nakaoka et al., Phys. Rev. E 92, 022402 (2015)]. In particular, we extracted the individual contributions of water and methanol molecules to the total FC and found that the molecular FC for methanol was larger than that for water. We further showed that the reduction of the total solid-liquid FC upon the increase of the methanol molar fraction in the first adsorption layer occurred as a result of a decrease in the molecular number density as well as a decrease in the molecular FCs of both molecules. Analysis of the molecular orientation revealed that the decrease of the molecular FC of methanol resulted from changes of the contact feature onto the solid surface. Specifically, methanol molecules near the solid surface had their C-O bond parallel to the surface with both CH3 and O sites contacting the solid at low methanol molar fraction, while they had their C-O bond outward from the surface with only the CH3 site contacting the solid at higher methanol molar fraction. The mechanisms discussed in this work could be used to search for alternative water additives to further reduce the solid-liquid friction.

  17. Characterization of nonpolar a-plane InGaN/GaN multiple quantum well using double nanopillar SiO2 mask

    Science.gov (United States)

    Son, Ji-Su; Honda, Yoshio; Yamaguchi, Masahito; Amano, Hiroshi

    2014-01-01

    The characteristics of nonpolar a-plane (11\\bar{2}0) GaN (a-GaN) grown using single and double nanopillar SiO2 masks were investigated. The two nanopillar SiO2 masks were directly fabricated on an r-plane sapphire substrate and a-GaN by the epitaxial lateral overgrowth (ELOG) technique. Through the use of the single and double nanopillar SiO2 masks, the crystalline quality and optical properties of a-GaN were markedly improved because of the nanoscale ELOG effect and a number of voids in the single and double nanopillar SiO2 mask areas in comparison with the planar sample. The submicron pit densities of the planar, single, and double nanopillar mask samples were ˜2 × 109, ˜7 × 108, and ˜4 × 108 cm-2, respectively. The internal quantum efficiency (IQE) values at room temperature of three-period InGaN/GaN multiple quantum wells (MQWs) grown using the planar, single, and double nanopillar masks were 45, 60, and 68% at a carrier concentration of 1.0 × 1018 cm-3, respectively.

  18. Media life of the young

    DEFF Research Database (Denmark)

    Westlund, Oscar; Bjur, Jakob

    2014-01-01

    This is a thorough investigation into contemporary young people and their media life. The article conceptualizes a typology of media life, drawing on a theoretical body involving the sociology of generations, life course research, media life and individualization. This empirically derived typology...... makes a strong instrument for an understanding of the media life of the young, furnishing insights into how they have constructed their use of media. The investigation is based on a robust national survey with Swedes born 1994–2001, conducted in 2010, and focusing on four media: television, gaming......, the Internet and mobile devices. Two of the findings are particularly surprising. Firstly, the results reveal that the young generally lead heterogeneous media lives, varying with age and sex. Secondly, although some young people literarily live their life in media, there are also de facto young who live...

  19. Children and the Mass Media

    Science.gov (United States)

    Winston, Shirley

    1970-01-01

    Resume of testimony given at hearings at the White House Conference on Children, September, 1970. Topics considered were the influence of the mass media on children and ways to improve media products. (NH)

  20. Media independence and dividend policy

    DEFF Research Database (Denmark)

    Farooq, Omar; Dandoune, Salma

    2012-01-01

    independence and dividend policies in emerging markets. Using a dataset from twenty three emerging markets, we show a significantly negative relationship between dividend policies (payout ratio and decision to pay dividend) and media independence. We argue that independent media reduces information asymmetries...... for stock market participants. Consequently, stock market participants in emerging markets with more independent media do not demand as high and as much dividends as their counterparts in emerging markets with less independent media. We also show that press independence is more important in defining......Can media pressurize managers to disgorge excess cash to shareholders? Do firms in countries with more independent media follow different dividend policies than firms with less independent media? This paper seeks to answer these questions and aims to document the relationship between media...

  1. DISKURSUS ISLAM DALAM KONSTRUKSI MEDIA

    Directory of Open Access Journals (Sweden)

    Muhammad Fahmi

    2015-12-01

    Full Text Available This paper aims to examine how the secular media in Surakarta represent Islam in the case of Charlie Hebdo. Therefore, this study used discourse analysis of Theo van Leeuwen focusing on how the subject or actor of the show in the media. This study concluded that the media represent Islam not only with “Western ideology” through idioms such as radical Islamist militants and terrorists, but also with "Islamic ideology". It is done through the construction of Islam as a religion of moderation and delegitimize Charlie Hebdo as magazine satyr abusing freedom. Various strategies are used ranging from strategy passivation to interdetermination. In this case, there are two poles of attraction in both media, namely the Western and Islamic ideology. If both media are quoting from Western sources, the Western ideology dominates the media narrative. Conversely, when both media used Islamic sources, the influence of Islamic ideology dominates the narrative of both media.

  2. Media independence and dividend policy

    DEFF Research Database (Denmark)

    Farooq, Omar; Dandoune, Salma

    2012-01-01

    for stock market participants. Consequently, stock market participants in emerging markets with more independent media do not demand as high and as much dividends as their counterparts in emerging markets with less independent media. We also show that press independence is more important in defining...... independence and dividend policies in emerging markets. Using a dataset from twenty three emerging markets, we show a significantly negative relationship between dividend policies (payout ratio and decision to pay dividend) and media independence. We argue that independent media reduces information asymmetries......Can media pressurize managers to disgorge excess cash to shareholders? Do firms in countries with more independent media follow different dividend policies than firms with less independent media? This paper seeks to answer these questions and aims to document the relationship between media...

  3. Editorial: Pedagogical Media Ecologies

    Directory of Open Access Journals (Sweden)

    Dorothee M. Meister

    2014-07-01

    Full Text Available From educational gaming through portable e-readers to cell phones, media are interpenetrating educational spaces and activities. Accordingly, understanding media in environmental or ecological terms has become increasingly important for education internationally. In North America, for example, the centenary of McLuhan’s birth has focused attention on approaches to media – whether oral, textual, electronic or digital– as a kind of environment in which education takes place. In parts of Europe, the so-called mediatic turn – following on the linguistic and iconic turns – has similarly emphasized the role of media as a condition for the possibility of educational activities and programs. With a few exceptions1 the papers in this special issue were first presented at the conference «Educational Media Ecologies: International Perspectives» which took place at the University of Paderborn, Germany, on March 27–28, 2012.2 The event was an interdisciplinary and transatlantic endeavor to bring together a wide range of perspectives on various issues relevant to educational media ecologies,3 and on related debates on mediation, medialization, mediatization, and mediality.4 The purpose of this volume, like the conference, is to foster and deepen international dialogue in the area of educational media. Areas of research and scholarship relevant to this dialogue include educational media, media literacy, educational philosophy, and media and cultural studies. The contributions, described below, put conceptual issues as well as social practices and applications at the center of the debate. Klaus Rummler opens the issue by clarifying the concept of ecology itself. Referencing a range of work over the past 50 years, Rummler describes how ecological models have been cast in sociological, semiotic, cultural, mediatic and other terms, and he explains the implications of these various perspectives for the study of educational contexts. Rummler also

  4. Competition and Commercial Media Bias

    OpenAIRE

    A. Blasco; F. Sobbrio

    2011-01-01

    This paper reviews the empirical evidence on commercial media bias (i.e., advertisers influence over media accuracy) and then introduces a simple model to summarize the main elements of the theoretical literature. The analysis provides three main policy insights for media regulators: i) Media regulators should target their monitoring efforts towards news contents upon which advertisers are likely to share similar preferences; ii) In advertising industries characterized by high correlation in ...

  5. The Weaponization of Social Media

    Science.gov (United States)

    2016-06-10

    media efforts will be compared to similar Western business and civic social media centric marketing efforts from both a technical and theoretical...THE WEAPONIZATION OF SOCIAL MEDIA A thesis presented to the Faculty of the U.S. Army Command and General Staff College in...The Weaponization of Social Media 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Jack B. Irby III, MAJ 5d

  6. Data Mining in Social Media

    Science.gov (United States)

    Barbier, Geoffrey; Liu, Huan

    The rise of online social media is providing a wealth of social network data. Data mining techniques provide researchers and practitioners the tools needed to analyze large, complex, and frequently changing social media data. This chapter introduces the basics of data mining, reviews social media, discusses how to mine social media data, and highlights some illustrative examples with an emphasis on social networking sites and blogs.

  7. Social Media in Classroom Teaching

    OpenAIRE

    Cavicchiolo, Elisa; Pelka, Bastian

    2013-01-01

    The use of social media for learning in schools is becoming more and more widespread and reflected in European context. But existing studies and learning material repositories predominantly consider social media as a new technology They are regarded as a technology enabling users to easily get in contact with other people. This paper puts social media in another context – they are regarded as a “social” innovation rather than a technological one. We see the innovative core of social media in ...

  8. The Economics of Internet Media

    OpenAIRE

    Peitz, Martin; Reisinger, Markus

    2014-01-01

    We survey the economics literature on media as it applies to the Internet. The Internet is an important driver behind media convergence and connects information and communication technologies. While new Internet media share some properties with traditional media, several novel features have appeared: On the content side, aggregation by third parties that have no editorial policy and user-generated content have become increasingly important. On the advertiser side, fine-tuned tailoring and tar...

  9. Going Public on Social Media

    Directory of Open Access Journals (Sweden)

    Greg Elmer

    2015-04-01

    Full Text Available This brief essay questions the disconnect between the financial goals of social media properties and the concerns of privacy advocates and other new media critics. It is argued that critics of social media often fail to recognize the financial imperative of social media companies, one that requires users to divulge and publicize ever more granular aspects of their daily lives, thoughts, and feelings.

  10. Documentary Media and Religious Communities

    Directory of Open Access Journals (Sweden)

    Marie-Therese Mäder

    2015-11-01

    Full Text Available The article considers four spaces where media processes involve religious communities and agents: the spaces of production, of representation, of media communication, and of distribution network and institutional framework for circulation. These three spaces systematise the research question posed to the specific source. Furthermore the concept documentary media as viewed from a semio-pragmatic perspective is introduced. Discussion of the commercial series I’m a Mormon shows how different modes define documentary media according to the three spaces.

  11. Nonpolar a-plane light-emitting diode with an in-situ SiNx interlayer on r-plane sapphire grown by metal-organic chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Fang Hao; Long Hao; Sang Li-Wen; Qi Sheng-Li; Xiong Chang; Yu Tong-Jun; Yang Zhi-Jian; Zhang Guo-Yi

    2011-01-01

    We report on the growth and fabrication of nonpolar a-plane light emitting diodes with an in-situ SiNx interlayer grown between the undoped a-plane GaN buffer and Si-doped GaN layer. X-ray diffraction shows that the crystalline quality of the GaN buffer layer is greatly improved with the introduction of the SiNx interlayer. The electrical properties are also improved. For example, electron mobility and sheet resistance are reduced from high resistance to 31.6 cm2/(V·s) and 460 Ω/□ respectively. Owing to the significant effect of the SiNx interlayer, a-plane LEDs are realized. Electroluminescence of a nonpolar a-plane light-emitting diode with a wavelength of 488nm is demonstrated.The emission peak remains constant when the injection current increases to over 20 mA.

  12. New Media, Legacy Media and Misperceptions Regarding Sourcing

    Directory of Open Access Journals (Sweden)

    Stan Diel

    2017-07-01

    Full Text Available Resource dependence theory and related theories of management suggest online-only news media may displace legacy news media, but until that happens the two systems are likely to be dependent on the same resource: news. This quantitative content analysis finds that the systems exist as parallel but distinctly separate entities. Websites associated with legacy news media such as newspapers publish mostly hard news or news analysis in the form of original work. New, online-only news media publish mostly unoriginal features, but the origins of much of the content published by onlineonly media are unclear.

  13. [Media for 21st century--towards human communication media].

    Science.gov (United States)

    Harashima, H

    2000-05-01

    Today, with the approach of the 21st century, attention is focused on multi-media communications combining computer, visual and audio technologies. This article discusses the communication media target and the technological problems constituting the nucleus of multi-media. The communication media is becoming an environment from which no one can escape. Since the media has such a great power, what is needed now is not to predict the future technologies, but to estimate the future world and take to responsibility for future environments.

  14. Media Competition and Electoral Politics

    NARCIS (Netherlands)

    Piolatto, A.; Schuett, F.

    2013-01-01

    Abstract: We build a framework linking competition in the media market to political participation, media slant, and selection of politicians. Media outlets report on the ability of candidates running for office and compete for audience through their choice of slant. Citizens derive utility from foll

  15. Transmedia Play: Literacy across Media

    Science.gov (United States)

    Alper, Meryl; Herr-Stephenson, Rebecca

    2013-01-01

    Transmedia play is a new way to understand how children develop critical media literacy and new media literacies through their interactions with contemporary media that links stories and structures across platforms. This essay highlights five characteristics of transmedia play that make it particularly useful for learning:…

  16. Media Violence and Young People.

    Science.gov (United States)

    Oaks, Harold R.

    1995-01-01

    Discusses the possibility of a connection between violence in the media and actual adolescent behavior. Explores the nature of the connection, why it exists, and possible courses of action to correct the problem. States that 3,000 studies have explored the link between media violence and adolescent behavior. Concludes that the media should show…

  17. Media Violence and Young People.

    Science.gov (United States)

    Oaks, Harold R.

    1995-01-01

    Discusses the possibility of a connection between violence in the media and actual adolescent behavior. Explores the nature of the connection, why it exists, and possible courses of action to correct the problem. States that 3,000 studies have explored the link between media violence and adolescent behavior. Concludes that the media should show…

  18. Social media and activist communication

    NARCIS (Netherlands)

    Poell, T.; van Dijck, J.; Atton, C.

    2015-01-01

    While the rise of social media has made activists much less dependent on television and mainstream newspapers, this certainly does not mean that activists have more control over the media environments in which they operate. Media power has neither been transferred to the public, nor to activists for

  19. Media Literacy. Technical Assistance Packet.

    Science.gov (United States)

    Join Together, Boston, MA.

    The media play an increasingly strong role in transmitting values; behaviors; social norms; attitudes; and knowledge to youth and adults. Media literacy involves the ability to ask questions about what is watched, heard, or read. It involves learning what to look for, what to ask, and how to question these many influences. Media literacy also…

  20. Characterizing Government Social Media Research

    DEFF Research Database (Denmark)

    Medaglia, Rony; Zheng, Lei

    2016-01-01

    As research on government social media continues to grow in quantity and scope, this area calls for mapping and systematization, in order to stimulate better-informed studies in the future. This paper draws on a comprehensive review of government social media literature in the e...... a four-point research agenda for future government social media research....