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Sample records for intramolecular electronic communication

  1. Bridge- and Solvent-Mediated Intramolecular Electronic Communications in Ubiquinone-Based Biomolecular Wires

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Yuan; Ma, Wei; Zhou, Hao; Cao, Xiao-Ming; Long, Yi-Tao

    2015-05-01

    Intramolecular electronic communications of molecular wires play a crucial role for developing molecular devices. In the present work, we describe different degrees of intramolecular electronic communications in the redox processes of three ubiquinone-based biomolecular wires (Bis-CoQ0s) evaluated by electrochemistry and Density Functional Theory (DFT) methods in different solvents. We found that the bridges linkers have a significant effect on the electronic communications between the two peripheral ubiquinone moieties and solvents effects are limited and mostly depend on the nature of solvents. The DFT calculations for the first time indicate the intensity of the electronic communications during the redox processes rely on the molecular orbital elements VL for electron transfer (half of the energy splitting of the LUMO and LUMO+1), which is could be affected by the bridges linkers. The DFT calculations also demonstrates the effect of solvents on the latter two-electron transfer of Bis-CoQ0s is more significant than the former two electrons transfer as the observed electrochemical behaviors of three Bis-CoQ0s. In addition, the electrochemistry and theoretical calculations reveal the intramolecular electronic communications vary in the four-electron redox processes of three Bis-CoQ0s.

  2. Bridge- and Solvent-Mediated Intramolecular Electronic Communications in Ubiquinone-Based Biomolecular Wires

    PubMed Central

    Liu, Xiao-Yuan; Ma, Wei; Zhou, Hao; Cao, Xiao-Ming; Long, Yi-Tao

    2015-01-01

    Intramolecular electronic communications of molecular wires play a crucial role for developing molecular devices. In the present work, we describe different degrees of intramolecular electronic communications in the redox processes of three ubiquinone-based biomolecular wires (Bis-CoQ0s) evaluated by electrochemistry and Density Functional Theory (DFT) methods in different solvents. We found that the bridges linkers have a significant effect on the electronic communications between the two peripheral ubiquinone moieties and solvents effects are limited and mostly depend on the nature of solvents. The DFT calculations for the first time indicate the intensity of the electronic communications during the redox processes rely on the molecular orbital elements VL for electron transfer (half of the energy splitting of the LUMO and LUMO+1), which is could be affected by the bridges linkers. The DFT calculations also demonstrates the effect of solvents on the latter two-electron transfer of Bis-CoQ0s is more significant than the former two electrons transfer as the observed electrochemical behaviors of three Bis-CoQ0s. In addition, the electrochemistry and theoretical calculations reveal the intramolecular electronic communications vary in the four-electron redox processes of three Bis-CoQ0s. PMID:25996306

  3. Solvent gating of intramolecular electron transfer

    SciTech Connect

    Miller, R.M. ); Spears, K.G.; Gong, J.H.; Wach, M. )

    1994-02-03

    The rates for ionic photodissociation of malachite green leucocyanide to form cyanide ion and a malachite green carbonium ion were measured as a function of solvent and temperature. The observed rates in mixtures of polar and nonpolar solvents all had an activation energy of about 1 kcal/mol for a wide range of dielectric constants. This dissociative intramolecular electron transfer (DIET) is unusual because it is the first example where solvent configurational entropy changes are required to enable a large amplitude molecular distortion leading to a nonadiabatic electron transfer and ionic dissociation. This solvent gated intramolecular electron-transfer mechanism is supported by analysis of the preexponential and activation energy trends in dipolar aprotic solven mixtures and alcohol solvents. The large amplitude motion is not separately measurable due to the slow gating rates, but viscosity effects on both the preexponential and the activation energy are analyzed to demonstrate consistency with a barrierless diffusion model having a structural dependence on electron-transfer rate. The rate has an inverse dependence on viscosity raised to the 0.53 power. 36 refs., 6 figs., 4 tabs.

  4. Communications Electronics.

    ERIC Educational Resources Information Center

    Vorderstrasse, Ron; Siebert, Leo

    This module is the third in a series of electronics publications and serves as a supplement to "General Electronics Technician." It is designed to provide students with an overview of the broad field of communications. Included are those tasks above the basic skills level that allow students to progress to a higher level of competency in the…

  5. Intramolecular Long-Distance Electron Transfer in Organic Molecules

    NASA Astrophysics Data System (ADS)

    Closs, Gerhard L.; Miller, John R.

    1988-04-01

    Intramolecular long-distance electron transfer (ET) has been actively studied in recent years in order to test existing theories in a quantitative way and to provide the necessary constants for predicting ET rates from simple structural parameters. Theoretical predictions of an ``inverted region,'' where increasing the driving force of the reaction will decrease its rate, have begun to be experimentally confirmed. A predicted nonlinear dependence of ET rates on the polarity of the solvent has also been confirmed. This work has implications for the design of efficient photochemical charge-separation devices. Other studies have been directed toward determining the distance dependence of ET reactions. Model studies on different series of compounds give similar distance dependences. When different stereochemical structures are compared, it becomes apparent that geometrical factors must be taken into account. Finally, the mechanism of coupling between donor and acceptor in weakly interacting systems has become of major importance. The theoretical and experimental evidence favors a model in which coupling is provided by the interaction with the orbitals of the intervening molecular fragments, although more experimental evidence is needed. Studies on intramolecular ET in organic model compounds have established that current theories give an adequate description of the process. The separation of electronic from nuclear coordinates is only a convenient approximation applied to many models, but in long-distance ET it works remarkably well. It is particularly gratifying to see Marcus' ideas finally confirmed after three decades of skepticism. By obtaining the numbers for quantitative correlations between rates and distances, these experiments have shown that saturated hydrocarbon fragments can ``conduct'' electrons over tens of angstroms. A dramatic demonstration of this fact has recently been obtained by tunneling electron microscopy on Langmuir-Blodgett films, showing in a

  6. Solvent reorganizational red-edge effect in intramolecular electron transfer.

    PubMed Central

    Demchenko, A P; Sytnik, A I

    1991-01-01

    Polar solvents are characterized by statistical distributions of solute-solvent interaction energies that result in inhomogeneous broadening of the solute electronic spectra. This allows photoselection of the high interaction energy part of the distribution by excitation at the red (long-wavelength) edge of the absorption bands. We observe that intramolecular electron transfer in the bianthryl molecule from the locally excited (LE) to the charge-transfer (CT) state, which requires solvent relaxation and does not occur in vitrified polar solutions, is dramatically facilitated in low-temperature propylene glycol glass by the red-edge excitation. This allows one to obtain spectroscopically the pure CT form and observe its dependence upon the relaxational properties of the solvent. A qualitative potential model of this effect is presented. PMID:11607224

  7. Structural studies of photoinduced intramolecular electron transfer in cyclopentadienylnickelnitrosyl

    SciTech Connect

    Chen, L.X.; Bowman, M.K.; Wang, Zhiyu; Norris, J.R. |; Montano, P.A. |

    1994-03-01

    A structural study based on EXAFS, FTIR, and optical absorption spectroscopies has been conducted on a photogenerated, metastable state of cyclopentadienylnickelnitrosyl (CpNiNO) produced by a reversible photochemical reaction. The photogenerated, metastable state with distinctively different EXAFS, IR, and optical absorption spectra from those of the ground state molecules was created by irradiating the sample with the 365 nm line of a mercury lamp at 20K . At the same temperature, the reverse reaction was induced by irradiation with the 313 nm line from the mercury lamp. Based on the analysis of the EXAFS data, the photogenerated, metastable state of CpNiNO has undergone considerable nuclear rearrangements compared to its ground state. The nuclear movement is characterized by a 0.12{angstrom} elongation of Ni-N bond and by a bending of Ni-N-O. A shift of the N-O stretching frequency from 1824 to 1387 cm{sup {minus}1} was observed in the photoinduced reaction with 365 nm light, implying that a NO{sup {minus}} like species results from intramolecular electron transfer from Ni to NO. The changes in the absorption spectra for the same reaction showed reduced absorption of the 385 nm band and a newly generated broad band near IR region. Temperature dependence of the Debye-Waller factor of CpNiNO was in good agreement with the diatomic harmonic oscillator for the Ni-N bond, but deviated for the Ni-O and the Ni-C bonds. Based on the structures obtained from EXAFS, ZINDO calculations for both the ground state and the photogenerated, metastable state of CpNiNO reproduced the general features of the observed absorption spectra and qualitatively explained the wavelength dependence of the reaction. The calculated partial charges on each atom in the ground state and the photogenerated, metastable state of CpNiNO are consistent with intramolecular electron transfer upon photoexcitation by 365 nm light.

  8. Intramolecular electronic energy transfer in bichromophoric molecular macrocyclic systems

    NASA Astrophysics Data System (ADS)

    Speiser, Shammai

    1993-01-01

    The structures and spectral properties of several bichromophoric molecules, suitable for optical data processing, are presented. The bichromophoric molecules are composed of an aromatic ring connected by two methylene chains to an (alpha) -diketone moiety. Both the absorption and emission spectra of these compounds can be attributed to a superposition of the individual spectra of the separate chromophores. The critical transfer radia for electronic energy transfer from the aromatic (donor) chromophore to the (alpha) -diketone (acceptor) chromophore was calculated from the spectral overlap between the fluorescence spectrum of the aromatic ring with the absorption spectrum of the (alpha) -diketone chromophore. The results show that this series of molecules is well suited for a mechanistic study of short-range intramolecular electronic energy transfer (intra-EET). The temperature and the molecular structure dependence of the intra-EET efficiency in this series was measured and analyzed for both singlet-singlet and triplet-triplet routes. The results show that the transfer efficiency is strongly temperature and structure dependent, indicating that exchange interaction is responsible for intra-EET between close chromophores in a bichromophoric molecule. The relative contributions of interchromophoric distance and that of the relative orientation of the two chromophores to exchange interaction are discussed.

  9. Intramolecular Communication in Anionic Oxidized Phosphanes through a Chelated Proton.

    PubMed

    Popescu, A R; Rojo, I; Teixidor, F; Sillanpää, R; Viñas, C

    2015-06-01

    Oxidation of the 1,2-(PR2 )2 -1,2-closo-C2 B10 H10 (R=Ph, iPr) platform with hydrogen peroxide in acetone is a two-step procedure in which partial deboronation of the closo cluster and oxidation of the phosphorus atoms occur. Based on NMR spectroscopic and kinetic data, we demonstrate that the phosphorus atoms are oxidized in the first step, followed by cluster deboronation. DFT calculations and natural-bond orbital (NBO) analysis were used to obtain insight into the electronic structures of diphosphane ortho-carborane derivatives. PMID:25926362

  10. Approach to interfacial and intramolecular electron transfer of the diheme protein cytochrome c4 assembled on Au(111) surfaces.

    PubMed

    Chi, Qijin; Zhang, Jingdong; Arslan, Taner; Borg, Lotte; Pedersen, Gert W; Christensen, Hans E M; Nazmudtinov, Renat R; Ulstrup, Jens

    2010-04-29

    Intramolecular electron transfer (ET) between metal centers is a core feature of large protein complexes in photosynthesis, respiration, and redox enzyme catalysis. The number of microscopic redox potentials and ET rate constants is, however, prohibitive for experimental cooperative ET mapping, but two-center proteins are simple enough to offer complete communication networks. At the same time, multicenter redox proteins operate in membrane environments where conformational dynamics may lead to gated ET features different from conditions in homogeneous solution. The bacterial respiratory diheme protein Pseudomonas stutzeri cytochrome c(4) has been a target for intramolecular, interheme ET. We report here voltammetric and in situ scanning tunneling microscopy (STM) data for P. stutzeri cyt c(4) at single-crystal, atomically planar Au(111)-electrode surfaces modified by variable-length omega-mercapto-alkanoic carboxylic acids. As evidenced by in situ STM, the strongly dipolar protein is immobilized in a close to vertical orientation at this surface with the positively charged high-potential heme domain adjacent to the electrode. This orientation gives asymmetric voltammograms with two one-ET peaks in the cathodic direction and a single two-ET peak in the anodic direction. Intramolecular, interheme ET with high, 8,000-30,000 s(-1), rate constants is notably an essential part of this mechanism. The high rate constants are in striking contrast to ET reactions of P. stutzeri cyt c(4) with small reaction partners in homogeneous solution for which kinetic analysis clearly testifies to electrostatic cooperative effects but no intramolecular, interheme ET higher than 0.1-10 s(-1). This difference suggests a strong gating feature of the process. On the basis of the three-dimensional structure of P. stutzeri cyt c(4), gating is understandable due to the through-space, hydrogen-bonded electronic contact between the heme propionates which is highly sensitive to environmental

  11. TD-DFT study on electron transfer mobility and intramolecular hydrogen bond of substituted indigo derivatives

    NASA Astrophysics Data System (ADS)

    Ma, Chi; Li, Hui; Yang, Yonggang; Li, Donglin; Liu, Yufang

    2015-10-01

    The density functional theory (DFT) and time-dependent density functional theory (TDDFT) method were carried out to investigate the ground and excited states of indigo and its derivative molecules. The results demonstrate that the intramolecular hydrogen bond I is weakened and the intramolecular hydrogen bond II is strengthened upon photo-excitation to the S1 state. In the absorption spectra, the substitution at R4R4, of indigo causes a significant redshift. In addition, the halogen substitution obviously increases the electron transfer mobility of indigo. It is proved that the halogen substitution may be a new method to design high performance organic semiconductors.

  12. Mechanisms of Intramolecular Communication in a Hyperthermophilic Acylaminoacyl Peptidase: A Molecular Dynamics Investigation

    PubMed Central

    Papaleo, Elena; Renzetti, Giulia; Tiberti, Matteo

    2012-01-01

    Protein dynamics and the underlying networks of intramolecular interactions and communicating residues within the three-dimensional (3D) structure are known to influence protein function and stability, as well as to modulate conformational changes and allostery. Acylaminoacyl peptidase (AAP) subfamily of enzymes belongs to a unique class of serine proteases, the prolyl oligopeptidase (POP) family, which has not been thoroughly investigated yet. POPs have a characteristic multidomain three-dimensional architecture with the active site at the interface of the C-terminal catalytic domain and a β-propeller domain, whose N-terminal region acts as a bridge to the hydrolase domain. In the present contribution, protein dynamics signatures of a hyperthermophilic acylaminoacyl peptidase (AAP) of the prolyl oligopeptidase (POP) family, as well as of a deletion variant and alanine mutants (I12A, V13A, V16A, L19A, I20A) are reported. In particular, we aimed at identifying crucial residues for long range communications to the catalytic site or promoting the conformational changes to switch from closed to open ApAAP conformations. Our investigation shows that the N-terminal α1-helix mediates structural intramolecular communication to the catalytic site, concurring to the maintenance of a proper functional architecture of the catalytic triad. Main determinants of the effects induced by α1-helix are a subset of hydrophobic residues (V16, L19 and I20). Moreover, a subset of residues characterized by relevant interaction networks or coupled motions have been identified, which are likely to modulate the conformational properties at the interdomain interface. PMID:22558199

  13. Chemoselective Intramolecular Carbonyl Ylide Formation through Electronically Differentiated Malonate Diesters.

    PubMed

    Nakhla, Mina C; Lee, Che-Wah; Wood, John L

    2015-12-01

    A method for chemoselective carbonyl ylide formation utilizing the Rh(II) catalyzed decomposition of electronically differentiated diazo malonates is disclosed. Treatment of ethyl, trifluoro ethyl diazo malonate with a Rh(II) catalyst selectively forms a carbonyl ylide from the relatively electron rich ethyl ester. This carbonyl ylide can be trapped by various alkynes giving highly functionalized oxabicyclic compounds in a chemo-, regio-, and diastereoselective fashion. PMID:26584509

  14. Electronic communication. Part III.

    PubMed

    Bergren, M D

    1995-02-01

    This is the concluding article of a three-part series on electronic communication for school nurses. The October 1994 column described electronic communication and the hardware and software required. The December 1994 column examined e-mail, bulletin boards, databases, and file transfers. This column will list many health and nursing resources available on-line. Some of the resources are available only through the Internet. Others are accessible by more than one route: dial-in, telnet, gopher, or world wide web. A few of the services, such as MEDLINE, are only accessed with purchased accounts (Glowniak & Bushway, 1994). The electronic resources of interest to school nurses are so numerous it would be impossible to cite all of them in a column of this length. Selected resources for the school health provider will be listed in alphabetical order. PMID:7767047

  15. Auger electron spectroscopy as a tool for measuring intramolecular charges of adsorbed molecules

    NASA Astrophysics Data System (ADS)

    Magkoev, T. T.

    A way for the determination of the values of intramolecular charges of adsorbed molecules of some binary dielectrics, based on Auger electron spectroscopy (AES), is proposed. These values can be obtained from the coverage dependences of the ratios of intensities of anion KL 23L 23 and KL 1L 1 Auger transitions, which are sensitive to the amount of charge at the 2p-orbitals. As an example, MgO adsorbed on Mo(110) is presented.

  16. Auger electron spectroscopy as a tool for measuring intramolecular charges of adsorbed molecules

    NASA Astrophysics Data System (ADS)

    Magkoev, T. T.

    1993-10-01

    A way for the determination of the values of intramolecular charges of adsorbed molecules of some binary dielectrics, based on Auger electron spectroscopy (AES), is proposed. These values can be obtained from the coverage dependences of the ratios of intensities of anion KL 23L 23 and KL 1L 1 Auger transitions, which are sensitive to the amount of charge at the 2p-orbitals. As an example, MgO adsorbed on Mo(110) is presented.

  17. An intramolecular inverse electron demand Diels–Alder approach to annulated α-carbolines

    PubMed Central

    Ma, Zhiyuan; Ni, Feng; Woo, Grace H C; Lo, Sie-Mun; Roveto, Philip M; Schaus, Scott E

    2012-01-01

    Summary Intramolecular inverse electron demand cycloadditions of isatin-derived 1,2,4-triazines with acetylenic dienophiles tethered by amidations or transesterifications proceed in excellent yields to produce lactam- or lactone-fused α-carbolines. Beginning with various isatins and alkynyl dienophiles, a pilot-scale library of eighty-eight α-carbolines was prepared by using this robust methodology for biological evaluation. PMID:23015831

  18. Au25 Clusters as Electron-Transfer Catalysts Induced the Intramolecular Cascade Reaction of 2-nitrobenzonitrile

    PubMed Central

    Chong, Hanbao; Li, Peng; Wang, Shuxin; Fu, Fangyu; Xiang, Ji; Zhu, Manzhou; Li, Yadong

    2013-01-01

    Design of atomically precise metal nanocluster catalysts is of great importance in understanding the essence of the catalytic reactions at the atomic level. Here, for the first time, Au25z nanoslusters were employed as electron transfer catalysts to induce an intramolecular cascade reaction at ambient conditions and gave rise to high conversion (87%) and selectivity (96%). Electron spin-resonance spectra indeed confirmed the consecutive electron transfer process and the formation of N radical. UV-vis absorption spectra also verified Au25z was intact after the catalytic circle. Our research may open up wide opportunities for extensive organic reactions catalyzed by Au25z. PMID:24225495

  19. Design Principles of Electronic Couplings for Intramolecular Singlet Fission in Covalently-Linked Systems.

    PubMed

    Ito, Soichi; Nagami, Takanori; Nakano, Masayoshi

    2016-08-11

    We theoretically investigate the singlet fission in three types of covalently-linked systems, that is, ortho-, meta- and para-linked pentacene dimers, where these are shown to have significantly different singlet fission rates. Each molecule is composed of two chromophores (pentacenes), which are active sites for singlet fission, and covalent bridges linking them. We clarify the origin of the difference in the electronic couplings in these systems, which are found to well support a recent experimental observation. It is also found that the next-nearest-neighbor interaction is indispensable for intramolecular singlet fission in these systems. On the basis of these results, we present design principles for efficient intramolecular singlet fission in covalently-linked systems and demonstrate the performance by using several novel conjugated linkers. PMID:27448100

  20. Negative resists for electron-beam lithography utilizing acid-catalyzed intramolecular dehydration of phenylcarbinol

    NASA Astrophysics Data System (ADS)

    Migitaka, Sonoko; Uchino, Shou-ichi; Ueno, Takumi; Yamamoto, Jiro; Kojima, Kyoko; Hashimoto, Michiaki; Shiraishi, Hiroshi

    1996-06-01

    Acid-catalyzed intramolecular dehydration of phenylcarbinol is used to design highly sensitive negative resists for electron beam lithography. Of the phenylcarbinol resists evaluated in this study, the resist composed of 1,3-bis(alpha-hydroxyisopropyl)benzene (Diol-1), m/p-cresol novolak resin, and diphenyliodonium triflate (DIT) shows the best lithographic performance in terms of sensitivity and resolution. Fine 0.25-micrometer line-and-space patterns were formed by using the resist containing Diol-1 with a dose of 3.6 (mu) C/cm2 in conjunction with a 50 kV electron beam exposure system.

  1. Electronic Communication and Decision Making.

    ERIC Educational Resources Information Center

    Feldman, M. S.; Sarbaugh-Thompson, M.

    1996-01-01

    Electronic communication can either facilitate or sabotage decision-making contexts. This article formulates recommendations about when and how to use electronic communication to enhance decision making and describes various decision contexts. Solutions to communication problems such as groupthink, social deadlock, bureaucratic isolation from…

  2. Analytical model for rates of electron attachment and intramolecular electron transfer in electron transfer dissociation mass spectrometry.

    PubMed

    Simons, Jack

    2010-05-26

    A new physical model is put forth to allow the prediction of electron transfer rates and distances for (i) intramolecular transfer from an n > or = 3 Rydberg orbital on a positive site to a disulfide or amide bond site and (ii) intermolecular transfer from an anion donor to an n > or = 3 Rydberg orbital of a positively charged polypeptide. Although ab initio methods have proven capable of handling such electron transfer events when the Rydberg orbital has principal quantum number n = 3, they have proven to be incapable of handling Rydberg states having quantum number n > 3, so having a new tool capable of handling n > 3 Rydberg states is important. The model (i) focuses on each Rydberg orbital's large peak of high amplitude, (ii) approximates the electron density within this peak as constant within a radial shell characterized by a radius and thickness T both of which depend on the quantum number n, and (iii) assumes that strong coupling (either with an orbital of an anion donor or to a disulfide sigma* or a backbone amide pi* orbital) occurs when the valence orbital penetrates fully within the radial shell of the Rydberg orbital. These assumptions permit a derivation of the ratios of rates of electron transfer for n > 3 to those for n = 3. Combining these ratios with ab initio rates for n = 3 allows one to make rate predictions for inter- and intramolecular electron transfer involving Rydberg orbitals appropriate to the electron transfer dissociation process. One important prediction of this model is that the combination of large-penetration and Landau-Zener surface-crossing conditions places very severe limitations on which Rydberg levels can initially be populated in electron transfer dissociation. Another prediction is that a Rydberg orbital of a given principal quantum number n has a limited range of distances over which it can transfer an electron; sigma* or pi* orbitals either too far from or too close to a given Rydberg orbital cannot accept an electron

  3. Application of time-resolved resonance Raman spectroscopy to intramolecular electron transfer

    SciTech Connect

    Schoonover, J.R.; Strouse, G.F.; Chen, P.; Bates, D.; Meyer, T.J. )

    1993-06-09

    Time-resolved resonance Raman spectroscopy has been applied for the first time to the study of intramolecular electron transfer in a chromophore-quencher complex, based on a metal-to-ligand charge-transfer (MLCT) excited state. These measurements allow for (1) the identification of redox sites that are reached following excitation and (2) the inferring of structural information in short-lived intermediates. This technique is a more sensitive probe than transient absorption as shown by its application to the redox-separated complex shown below involving a pyridinium acceptor and a phenothiazine donor.

  4. Intramolecular allosteric communication in dopamine D2 receptor revealed by evolutionary amino acid covariation

    PubMed Central

    Sung, Yun-Min; Wilkins, Angela D.; Rodriguez, Gustavo J.; Wensel, Theodore G.; Lichtarge, Olivier

    2016-01-01

    The structural basis of allosteric signaling in G protein-coupled receptors (GPCRs) is important in guiding design of therapeutics and understanding phenotypic consequences of genetic variation. The Evolutionary Trace (ET) algorithm previously proved effective in redesigning receptors to mimic the ligand specificities of functionally distinct homologs. We now expand ET to consider mutual information, with validation in GPCR structure and dopamine D2 receptor (D2R) function. The new algorithm, called ET-MIp, identifies evolutionarily relevant patterns of amino acid covariations. The improved predictions of structural proximity and D2R mutagenesis demonstrate that ET-MIp predicts functional interactions between residue pairs, particularly potency and efficacy of activation by dopamine. Remarkably, although most of the residue pairs chosen for mutagenesis are neither in the binding pocket nor in contact with each other, many exhibited functional interactions, implying at-a-distance coupling. The functional interaction between the coupled pairs correlated best with the evolutionary coupling potential derived from dopamine receptor sequences rather than with broader sets of GPCR sequences. These data suggest that the allosteric communication responsible for dopamine responses is resolved by ET-MIp and best discerned within a short evolutionary distance. Most double mutants restored dopamine response to wild-type levels, also suggesting that tight regulation of the response to dopamine drove the coevolution and intramolecular communications between coupled residues. Our approach provides a general tool to identify evolutionary covariation patterns in small sets of close sequence homologs and to translate them into functional linkages between residues. PMID:26979958

  5. Intramolecular allosteric communication in dopamine D2 receptor revealed by evolutionary amino acid covariation.

    PubMed

    Sung, Yun-Min; Wilkins, Angela D; Rodriguez, Gustavo J; Wensel, Theodore G; Lichtarge, Olivier

    2016-03-29

    The structural basis of allosteric signaling in G protein-coupled receptors (GPCRs) is important in guiding design of therapeutics and understanding phenotypic consequences of genetic variation. The Evolutionary Trace (ET) algorithm previously proved effective in redesigning receptors to mimic the ligand specificities of functionally distinct homologs. We now expand ET to consider mutual information, with validation in GPCR structure and dopamine D2 receptor (D2R) function. The new algorithm, called ET-MIp, identifies evolutionarily relevant patterns of amino acid covariations. The improved predictions of structural proximity and D2R mutagenesis demonstrate that ET-MIp predicts functional interactions between residue pairs, particularly potency and efficacy of activation by dopamine. Remarkably, although most of the residue pairs chosen for mutagenesis are neither in the binding pocket nor in contact with each other, many exhibited functional interactions, implying at-a-distance coupling. The functional interaction between the coupled pairs correlated best with the evolutionary coupling potential derived from dopamine receptor sequences rather than with broader sets of GPCR sequences. These data suggest that the allosteric communication responsible for dopamine responses is resolved by ET-MIp and best discerned within a short evolutionary distance. Most double mutants restored dopamine response to wild-type levels, also suggesting that tight regulation of the response to dopamine drove the coevolution and intramolecular communications between coupled residues. Our approach provides a general tool to identify evolutionary covariation patterns in small sets of close sequence homologs and to translate them into functional linkages between residues. PMID:26979958

  6. Mapping the intramolecular contributions to the inelastic electron tunneling signal of a molecular junction

    NASA Astrophysics Data System (ADS)

    Foti, Giuseppe; Vázquez, Héctor

    2016-07-01

    We present a quantitative analysis of the intramolecular origin of the inelastic electron tunneling signal of a molecular junction. We use density-functional theory to study a representative conjugated molecule with a low degree of symmetry and calculate, for all modes, the different contributions that give rise to the vibrational spectrum. These local contributions involve products of scattering states with electron-phonon matrix elements and thus encode information on both the vibrational modes and the electronic structure. We separate these intra- and interatomic terms and draw a pattern of addition or cancellation of these partial contributions throughout the inelastic spectrum. This allows for a quantitative relation between the degree of symmetry of each vibrational mode, its inelastic signal, and the locality of selection rules.

  7. Kinetics of Intramolecular Electron Transfer in Cytochrome bo3 from Escherichia coli

    PubMed Central

    Ching, Erin; Gennis, Robert B.; Larsen, Randy W.

    2003-01-01

    We have examined the temperature dependence of the intramolecular electron transfer (ET) between heme b and heme o3 in CO-mixed valence cytochrome bo3 (Cbo) from Escherichia coli. Upon photolysis of CO-mixed valence Cbo rapid ET occurs between heme o3 and heme b with a rate constant of 2.2 × 105 s−1 at room temperature. The corresponding rate of CO recombination is found to be 86 s−1. From Eyring plots the activation energies for these two processes are found to be 3.4 kcal/mol and 6.7 kcal/mol for the ligand binding and ET reactions, respectively. Using variants of the Marcus equation the reorganization energy (λ), electronic coupling factor (HAB), and the ET distance were found to be 1.4 ± 0.2 eV, (2 ± 1) × 10−3 eV, and 9 ± 1 Å, respectively. These values are quite distinct from the analogous values previously obtained for bovine heart cytochrome c oxidase (CcO) (0.76 eV, 9.9 × 10−5 eV, 13.2 Å). The differences in mechanisms/pathways for heme b/heme o3 and heme a/heme a3 ET suggested by the Marcus parameters can be attributed to structural changes at the CuB site upon change in oxidation state as well as differences in electronic coupling pathways between Heme b and heme o3. PMID:12668481

  8. Spectroelectrochemical investigation of intramolecular and interfacial electron-transfer rates reveals differences between nitrite reductase at rest and during turnover.

    PubMed

    Krzemiński, Łukasz; Ndamba, Lionel; Canters, Gerard W; Aartsma, Thijs J; Evans, Stephen D; Jeuken, Lars J C

    2011-09-28

    A combined fluorescence and electrochemical method is described that is used to simultaneously monitor the type-1 copper oxidation state and the nitrite turnover rate of a nitrite reductase (NiR) from Alcaligenes faecalis S-6. The catalytic activity of NiR is measured electrochemically by exploiting a direct electron transfer to fluorescently labeled enzyme molecules immobilized on modified gold electrodes, whereas the redox state of the type-1 copper site is determined from fluorescence intensity changes caused by Förster resonance energy transfer (FRET) between a fluorophore attached to NiR and its type-1 copper site. The homotrimeric structure of the enzyme is reflected in heterogeneous interfacial electron-transfer kinetics with two monomers having a 25-fold slower kinetics than the third monomer. The intramolecular electron-transfer rate between the type-1 and type-2 copper site changes at high nitrite concentration (≥520 μM), resulting in an inhibition effect at low pH and a catalytic gain in enzyme activity at high pH. We propose that the intramolecular rate is significantly reduced in turnover conditions compared to the enzyme at rest, with an exception at low pH/nitrite conditions. This effect is attributed to slower reduction rate of type-2 copper center due to a rate-limiting protonation step of residues in the enzyme's active site, gating the intramolecular electron transfer. PMID:21863850

  9. Role of Intramolecular Vibrations in Long-Range Electron Transfer between Pheophytin and Ubiquinone in Bacterial Photosynthetic Reaction Centers

    PubMed Central

    Borrelli, Raffaele; Di Donato, Mariangela; Peluso, Andrea

    2005-01-01

    The dynamics of the elementary electron transfer step between pheophytin and primary ubiquinone in bacterial photosynthetic reaction centers is investigated by using a discrete state approach, including only the intramolecular normal modes of vibration of the two redox partners. The whole set of normal coordinates of the acceptor and donor groups have been employed in the computations of the Hamiltonian matrix, to reliably account both for shifts and mixing of the normal coordinates, and for changes in vibrational frequencies upon ET. It is shown that intramolecular modes provide not only a discrete set of states more strongly coupled to the initial state but also a quasicontinuum of weakly coupled states, which account for the spreading of the wave packet after ET. The computed transition probabilities are sufficiently high for asserting that electron transfer from bacteriopheophytin to the primary quinone can occur via tunneling solely promoted by intramolecular modes; the transition times, computed for different values of the electronic energy difference and coupling term, are of the same order of magnitude (102 ps) of the observed one. PMID:15894646

  10. Electronic Journals, the Internet, and Scholarly Communication.

    ERIC Educational Resources Information Center

    Kling, Rob; Callahan, Ewa

    2003-01-01

    Examines the role of the Internet in supporting scholarly communication via electronic journals. Topics include scholarly electronic communication; a typology of electronic journals; models of electronic documents and scholarly communication forums; publication speed; costs; pricing; access and searching; citations; interactivity; archiving and…

  11. Photoinduced intramolecular charge transfer in an electronically modified flavin derivative: roseoflavin.

    PubMed

    Karasulu, Bora; Thiel, Walter

    2015-01-22

    The photophysical properties of a push-pull flavin derivative, roseoflavin (RoF), are investigated in different surroundings at the molecular level, with focus on intramolecular charge transfer (ICT). Time-dependent density functional theory (TD-DFT, CAM-B3LYP functional) and DFT-based multireference configuration interaction (DFT/MRCI) are used to compute excited-state energies and one-electron properties of a truncated RoF model, roseolumiflavin (RoLF). Solvent effects are taken into account implicitly by the conductor-like polarizable continuum model and explicitly through a microsolvation scheme. In the gas phase, the calculations predict no crossing between the lowest locally excited (LE) and charge-transfer (CT) states upon twisting the dimethylamine donor group relative to the plane of the isoalloxazine acceptor moiety, whereas this crossing is found to be facile in solution (i.e., in water or benzene). Crossing of the LE and CT states facilitates ICT, which is the main cause of the fluorescence quenching and dual fluorescence character experimentally observed for roseoflavin in solution. The barrier for the ICT process is computed to be lower in water than in benzene, consistent with the enhanced ICT rates observed in more polar solvents. We present a detailed study of the molecular mechanism of the photoinduced ICT process in RoLF. For a typical donor-acceptor chromophore, three such mechanisms are discussed in the literature, which differ in the alignment of the donor and acceptor planes, namely, planar ICT (PICT), perpendicular-twisted ICT (TICT), and wagging ICT (WICT). Our theoretical results suggest that the TICT mechanism is favored in RoLF. PMID:25214319

  12. High-resolution electronic spectroscopy of the doorway states to intramolecular charge transfer.

    PubMed

    Fleisher, Adam J; Bird, Ryan G; Zaleski, Daniel P; Pate, Brooks H; Pratt, David W

    2013-04-25

    Reported here are several of the ground, first, and second excited state structures and dipole moments of three benchmark intramolecular charge transfer (ICT) systems; 4-(1H-pyrrol-1-yl)benzonitrile (PBN), 4,4'-dimethylaminobenzonitrile (DMABN), and 4-(1-pyrrolidinyl)benzonitrile (PYRBN), isolated in the gas phase and probed by rotationally resolved spectroscopy in a molecular beam. The related molecules 1-phenylpyrrole (PP) and 4-aminobenzonitrile (ABN) also are discussed. We find that the S1 electronic state is of B symmetry in all five molecules. In PBN, a second excited state (S2) of A symmetry is found only ~400 cm(-1) above the presumed origin of the S1 state. The change in dipole moment upon excitation to the A state is measured to be Δμ ≈ 3.0 D, significantly smaller than the value predicted by theory and also smaller than that observed for the "anomalous" ICT band of PBN in solution. The B state dipole moments of DMABN and PYRBN are large, ~10.6 D, slightly larger than those attributed to "normal" LE fluorescence in solution. In addition, we find the unsaturated donor molecules (PP, PBN) to be twisted in their ground states and to become more planar upon excitation, even in the A state, whereas the saturated donor molecules (ABN, DMABN, PYRBN), initially planar, either remain planar or become more twisted in their excited states. It thus appears that the model that is appropriate for describing ICT in these systems depends on the geometry of the ground state. PMID:22913563

  13. Intermolecular electron transfer from intramolecular excitation and coherent acoustic phonon generation in a hydrogen-bonded charge-transfer solid.

    PubMed

    Rury, Aaron S; Sorenson, Shayne; Dawlaty, Jahan M

    2016-03-14

    Organic materials that produce coherent lattice phonon excitations in response to external stimuli may provide next generation solutions in a wide range of applications. However, for these materials to lead to functional devices in technology, a full understanding of the possible driving forces of coherent lattice phonon generation must be attained. To facilitate the achievement of this goal, we have undertaken an optical spectroscopic study of an organic charge-transfer material formed from the ubiquitous reduction-oxidation pair hydroquinone and p-benzoquinone. Upon pumping this material, known as quinhydrone, on its intermolecular charge transfer resonance as well as an intramolecular resonance of p-benzoquinone, we find sub-cm(-1) oscillations whose dispersion with probe energy resembles that of a coherent acoustic phonon that we argue is coherently excited following changes in the electron density of quinhydrone. Using the dynamical information from these ultrafast pump-probe measurements, we find that the fastest process we can resolve does not change whether we pump quinhydrone at either energy. Electron-phonon coupling from both ultrafast coherent vibrational and steady-state resonance Raman spectroscopies allows us to determine that intramolecular electronic excitation of p-benzoquinone also drives the electron transfer process in quinhydrone. These results demonstrate the wide range of electronic excitations of the parent of molecules found in many functional organic materials that can drive coherent lattice phonon excitations useful for applications in electronics, photonics, and information technology. PMID:26979698

  14. Intermolecular electron transfer from intramolecular excitation and coherent acoustic phonon generation in a hydrogen-bonded charge-transfer solid

    NASA Astrophysics Data System (ADS)

    Rury, Aaron S.; Sorenson, Shayne; Dawlaty, Jahan M.

    2016-03-01

    Organic materials that produce coherent lattice phonon excitations in response to external stimuli may provide next generation solutions in a wide range of applications. However, for these materials to lead to functional devices in technology, a full understanding of the possible driving forces of coherent lattice phonon generation must be attained. To facilitate the achievement of this goal, we have undertaken an optical spectroscopic study of an organic charge-transfer material formed from the ubiquitous reduction-oxidation pair hydroquinone and p-benzoquinone. Upon pumping this material, known as quinhydrone, on its intermolecular charge transfer resonance as well as an intramolecular resonance of p-benzoquinone, we find sub-cm-1 oscillations whose dispersion with probe energy resembles that of a coherent acoustic phonon that we argue is coherently excited following changes in the electron density of quinhydrone. Using the dynamical information from these ultrafast pump-probe measurements, we find that the fastest process we can resolve does not change whether we pump quinhydrone at either energy. Electron-phonon coupling from both ultrafast coherent vibrational and steady-state resonance Raman spectroscopies allows us to determine that intramolecular electronic excitation of p-benzoquinone also drives the electron transfer process in quinhydrone. These results demonstrate the wide range of electronic excitations of the parent of molecules found in many functional organic materials that can drive coherent lattice phonon excitations useful for applications in electronics, photonics, and information technology.

  15. Vertex function for the coupling of an electron with intramolecular phonons: Exact results in the antiadiabatic limit

    NASA Astrophysics Data System (ADS)

    Takada, Yasutami; Higuchi, Takatoshi

    1995-11-01

    The Green's-function techniques, especially the one developed in the preceding paper [Takada, Phys. Rev. B 52, 12 708 (1995)], are employed to calculate the electron-phonon vertex part as well as the electronic self-energy exactly on both real- and imaginary-frequency axes in the electron-phonon Holstein model with the on-site Coulomb repulsion in the limit in which the intramolecular phonon energy ω0 is much larger than the electronic bandwidth. The rigorous vertex part is found to diverge at the frequencies at which an electron is locked by such local phonons with an infinitely strong effective coupling. Characteristic frequencies of this divergence, which are not equal to multiples of ω0, are calculated as a function of the electron-phonon bare coupling constant. Our results for the self-energy are checked successfully with the exact ones obtained by the Lang-Firsov canonical transformation.

  16. How Intrinsic Molecular Dynamics Control Intramolecular Communication in Signal Transducers and Activators of Transcription Factor STAT5

    PubMed Central

    Langenfeld, Florent; Guarracino, Yann; Arock, Michel; Trouvé, Alain; Tchertanov, Luba

    2015-01-01

    Signal Transducer and Activator of Transcription STAT5 is a key mediator of cell proliferation, differentiation and survival. While STAT5 activity is tightly regulated in normal cells, its constitutive activation directly contributes to oncogenesis and is associated with a broad range of hematological and solid tumor cancers. Therefore the development of compounds able to modulate pathogenic activation of this protein is a very challenging endeavor. A crucial step of drug design is the understanding of the protein conformational features and the definition of putative binding site(s) for such modulators. Currently, there is no structural data available for human STAT5 and our study is the first footprint towards the description of structure and dynamics of this protein. We investigated structural and dynamical features of the two STAT5 isoforms, STAT5a and STAT5b, taken into account their phosphorylation status. The study was based on the exploration of molecular dynamics simulations by different analytical methods. Despite the overall folding similarity of STAT5 proteins, the MD conformations display specific structural and dynamical features for each protein, indicating first, sequence-encoded structural properties and second, phosphorylation-induced effects which contribute to local and long-distance structural rearrangements interpreted as allosteric event. Further examination of the dynamical coupling between distant sites provides evidence for alternative profiles of the communication pathways inside and between the STAT5 domains. These results add a new insight to the understanding of the crucial role of intrinsic molecular dynamics in mediating intramolecular signaling in STAT5. Two pockets, localized in close proximity to the phosphotyrosine-binding site and adjacent to the channel for communication pathways across STAT5, may constitute valid targets to develop inhibitors able to modulate the function-related communication properties of this signaling

  17. Enaminones in a multicomponent synthesis of 4-aryldihydropyridines for potential applications in photoinduced intramolecular electron-transfer systems

    PubMed Central

    Ibrahim, Maher R; Elnagdi, Mohamed H; John, Elizabeth; Ibrahim, Yehia A

    2012-01-01

    Summary An efficient three component reaction with enaminones, primary amines and aldehydes resulted in easy access to 1,4-dihydropyridines with different substituents at the 1-, 3-, 4- and 5-positions. Microwaves improved the reaction yield, reducing also considerably the reaction time and the amount of solvent used. Chiral primary amines gave chiral 1-substituted-1,4-dihydropyridines. The 4-(1-naphthyl) and 4-(phenanthren-9-yl)dihydropyridine derivatives exhibited an interesting photoluminescence behavior, which suggests their potential application as suitable photoinduced intramolecular electron-transfer systems. PMID:22509215

  18. Intramolecular electron transfer reactions in meso-(4-nitrophenyl)-substituted subporphyrins.

    PubMed

    Copley, Graeme; Oh, Juwon; Yoshida, Kota; Shimizu, Daiki; Kim, Dongho; Osuka, Atsuhiro

    2016-01-25

    A2B-type meso-(4-nitrophenyl)-substituted subporphyrins have been synthesized and shown to undergo very fast photoinduced intramolecular charge separation (CS) and charge recombination (CR) between the subporphyrin core and the meso-4-nitrophenyl group in CH2Cl2 as probed by femtosecond time-resolved transient absorption spectroscopy. Red-shifted emissions were detected from charge-separated states as a rare case for porphyrinoids. PMID:26645430

  19. Control of intramolecular electron transfer by protonation: Dimers and polymers containing ruthenium II/III and 44' azopyridine

    NASA Astrophysics Data System (ADS)

    Launay, Jean-Pierre; Marvaud, Valérie

    1992-07-01

    The association of pentammine ruthenium(II) with the reducible ligand 44' azopyridine leads to a pH induced redox reaction in which ruthenium is oxidized to the III state, while 44' azopyridine is reduced to hydrazopyridine. In this process, the conjugated ligand is transformed in a nonconjugated one, with loss of its intramolecular electron transfer properties. In order to exploit this control of an intramolecular electron transfer by a protonation process, we have prepared ``shish-kebab'' polymers by first inserting ruthenium in tetrakis (3,5-diterbutyl 4-hydroxyphenyl) porphyrin under a CO atmosphere. The resulting Ru(CO)porphyrin complex is photochemically decarbonylated in the presence of bridging ligands (44×azopyridine or pyrazine). Polymers are thus obtained, which can be oxidized by iodine, giving rise to intervalence transitions between ruthenium(II) and (III) in the near-infrared. This provides a convenient way to monitor electron transfer along the polymer chain. In the case of 44' azopyridine, the pH induced redox reaction is again observed. Starting from a homovalent ruthenium(II) chain, this gives the possibility to switch ``ON'' or ``OFF'' the intervalence transition by a protonation/deprotonation reaction.

  20. Photoinduced intramolecular electron transfer in a bridged C{sub 60}. (Acceptor)-Aniline (donor) system. Photophysical properties of the first `active` fullerene diad

    SciTech Connect

    Williams, R.M.; Zwier, J.M.; Verhoeven, J.W.

    1995-04-12

    A covalently functionalized fullerene comprising an electron donating aniline group coupled to the fullerene unit by a saturated heterocyclic bridge is shown to undergo a photoinduced intramolecular electron transfer process that causes quenching of the fluorescence of the adduct and strong decrease triplet population in polar solvents. VIS-absorption, fluorescence and phosphorescence at 77 K, triplet-triplet absorption, time resolved fluorescence and redox potentials of the fullerene adduct are presented. Analysis of the solvent dependence of the energetics of the intramolecular electron transfer is given and is in good agreement with the experimental results. 17 refs., 6 figs., 3 tabs.

  1. Mechanism of the reduction of the native intermediate in the multicopper oxidases: insights into rapid intramolecular electron transfer in turnover.

    PubMed

    Heppner, David E; Kjaergaard, Christian H; Solomon, Edward I

    2014-12-24

    The multicopper oxidases (MCOs) are the family of enzymes that catalyze the 4-electron reduction of O2 to H2O coupled to the four 1-electron oxidations of substrate. In the catalytic cycle electrons are transferred intramolecularly over ∼13 Å from a Type 1 (T1) Cu site that accepts electrons from substrate to a trinuclear Cu cluster (TNC) where O2 is reduced to H2O at rapid rates consistent with turnover (560 s(-1)). The oxygen reduction mechanism for the MCOs is well-characterized, whereas the rereduction is less understood. Our initial study of Rhus vernicifera Laccase (Heppner et al. J. Am. Chem. Soc. 2013, 135, 12212) experimentally established that the native intermediate (NI), the species formed upon O-O bond cleavage, is reduced with an IET rate >700 s(-1) and is the catalytically relevant fully oxidized form of the enzyme, rather than the resting state. In this report, we present kinetic and spectroscopic results coupled to DFT calculations that evaluate the mechanism of the 3 e(-)/3 H(+) reduction of NI, where all three catalytically relevant intramolecular electron transfer (IET) steps are rapid and involve three different structural changes. These three rapid IET processes reflect the sophisticated mechanistic control of the TNC to enable rapid turnover. All three IET processes are fast due to the associated protonation of the bridging oxo and hydroxo ligands, generated by O-O cleavage, to form water products that are extruded from the TNC upon full reduction, thereby defining a unifying mechanism for oxygen reduction and rapid IET by the TNC in the catalytic cycle of the MCOs. PMID:25490729

  2. Intramolecular electron transfer in fullerene/ferrocene based donor-bridge-acceptor dyads

    SciTech Connect

    Guldi, D.M.; Maggini, M.; Scorrano, G.; Prato, M.

    1997-02-05

    A systematic steady-state fluorescence and time-resolved flash photolytic investigation of a series of covalently linked fullerene/ferrocene based donor-bridge-acceptor dyads is reported as a function of the nature of the spacer between the donor site (ferrocene) and acceptor site (fullerene) and the dielectric constant of the medium. The fluorescence of the investigated dyads 2, 3, 4, 5, and 6 in methylcyclohexane at 77 K were substantially quenched, relative to N-methylfulleropyrrolidine 1, indicating intramolecular quenching of the fullerene excited singlet state. Excitation of N-methylfulleropyrrolidine revealed the immediate formation of the excited singlet state, with {lambda}{sub max} around 886 nm. A rapid intersystem crossing ({tau}{sub 1/2} = 1.2 ps ) to the excited triplet state was observed with characteristic absorption around 705 nm. Picosecond resolved photolysis of dyads 2-6 in toluene showed light-induced formation of the excited singlet state which undergoes rapid intramolecular quenching. Nanosecond-resolved photolysis of dyads 3 and 4 in degassed benzonitrile revealed long-lived charge separated states with characteristic fullerene radical-anion bands at {lambda}{sub max} = 1055 nm. 30 refs., 5 figs., 3 tabs.

  3. Intramolecular energy- and electron-transfer reactions in polymetallic complexes. Annual report

    SciTech Connect

    Peterson, J.D.

    1991-12-01

    The complexes (tpy)Ru(II)(tpp)Co(III)(PPhEt{sub 2})H{sub 2}{sup 3+}, (NC){sub 3}Fe(II)(tpp)Co(III)(PPhEt{sub 2})H{sub 2} and (NC){sub 3}Fe(II)(tpp)Co(III)(PPh{sub 3})H{sub 2} (where tpp = 2,3,5,6-tetrakis(2{prime}-pyridyl)pyrazine), were prepared and their photochemistry studied. Reasons for the low quantum yields for H{sub 2} production are discussed briefly. A series of FeRuRh complexes is being prepared. Plans for the coming year on intramolecular energy transfer and charge separation are discussed.

  4. Quantum effect of intramolecular high-frequency vibrational modes on diffusion-controlled electron transfer rate: From the weak to the strong electronic coupling regions

    SciTech Connect

    Zhu, Wenjuan; Zhao, Yi

    2007-05-14

    The Sumi-Marcus theory is extended by introducing two approaches to investigate electron transfer reactions from weak-to-strong electronic coupling regime. One of these approaches is the quantum R-matrix theory, useful for dealing with the intramolecular vibrational motions in the whole electronic coupling domain. The other is the split operator approach that is employed to solve the reaction-diffusion equation. The approaches are then applied to electron transfer in the Marcus inverted regime to investigate the nuclear tunneling effect on the long time rate and the survival probabilities. The numerical results illustrate that the adiabatic suppression obtained from the R-matrix approach is much smaller than that from the Landau-Zener theory whereas it cannot be predicted by the perturbation theory. The jointed effects of the electronic coupling and solvent relaxation time on the rates are also explored.

  5. Photochemically induced intramolecular six-electron reductive elimination and oxidative addition of nitric oxide by the nitridoosmate(VIII) anion.

    PubMed

    Thornley, Wyatt A; Bitterwolf, Thomas E

    2015-02-01

    UV photolysis of the nitridoosmate(VIII) anion, OsO3 N(-) , in low-temperature frozen matrices results in nitrogen-oxygen bond formation to give the Os(II) nitrosyl complex OsO2 (NO)(-) . Photolysis of the Os(II) nitrosyl product with visible wavelengths results in reversion to the parent Os(VIII) complex. Formally a six-electron reductive elimination and oxidative addition, respectively, this represents the first reported example of such an intramolecular transformation. DFT modelling of this reaction proceeds through a step-wise mechanism taking place through a side-on nitroxyl Os(VI) intermediate, OsO2 (η(2) -NO)(-) . PMID:25537499

  6. Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses

    SciTech Connect

    Canton, Sophie E.; Kjær, Kasper S.; Vankó, György; van Driel, Tim B.; Adachi, Shin -ichi; Bordage, Amélie; Bressler, Christian; Chabera, Pavel; Christensen, Morten; Dohn, Asmus O.; Galler, Andreas; Gawelda, Wojciech; Gosztola, David; Haldrup, Kristoffer; Harlang, Tobias; Liu, Yizhu; Møller, Klaus B.; Németh, Zoltán; Nozawa, Shunsuke; Pápai, Mátyás; Sato, Tokushi; Sato, Takahiro; Suarez-Alcantara, Karina; Togashi, Tadashi; Tono, Kensuke; Uhlig, Jens; Vithanage, Dimali A.; Wärnmark, Kenneth; Yabashi, Makina; Zhang, Jianxin; Sundström, Villy; Nielsen, Martin M.

    2015-03-02

    Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donor–acceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances. Thus experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined.

  7. Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses

    DOE PAGESBeta

    Canton, Sophie E.; Kjær, Kasper S.; Vankó, György; van Driel, Tim B.; Adachi, Shin -ichi; Bordage, Amélie; Bressler, Christian; Chabera, Pavel; Christensen, Morten; Dohn, Asmus O.; et al

    2015-03-02

    Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donor–acceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances.more » Thus experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined.« less

  8. Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses

    PubMed Central

    Canton, Sophie E.; Kjær, Kasper S.; Vankó, György; van Driel, Tim B.; Adachi, Shin-ichi; Bordage, Amélie; Bressler, Christian; Chabera, Pavel; Christensen, Morten; Dohn, Asmus O.; Galler, Andreas; Gawelda, Wojciech; Gosztola, David; Haldrup, Kristoffer; Harlang, Tobias; Liu, Yizhu; Møller, Klaus B.; Németh, Zoltán; Nozawa, Shunsuke; Pápai, Mátyás; Sato, Tokushi; Sato, Takahiro; Suarez-Alcantara, Karina; Togashi, Tadashi; Tono, Kensuke; Uhlig, Jens; Vithanage, Dimali A.; Wärnmark, Kenneth; Yabashi, Makina; Zhang, Jianxin; Sundström, Villy; Nielsen, Martin M.

    2015-01-01

    Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donor–acceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances. Experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined. PMID:25727920

  9. Peripheral substitution as a tool for tuning electron-accepting properties of phthalocyanine analogs in intramolecular charge transfer.

    PubMed

    Cidlina, Antonin; Novakova, Veronika; Miletin, Miroslav; Zimcik, Petr

    2015-04-21

    The intramolecular charge transfer (ICT), which is a pathway for excited state relaxation, was studied on the newly synthesized zinc(ii) complexes of tetrapyrazinoporphyrazines bearing one fixed donor (i.e., a dialkylamino substituent). The rest of the peripheral substituents on the core was designed with respect to their different electronic effects (OBu, neopentyl, StBu, COOBu). The photophysical (singlet oxygen and fluorescence quantum yields) and electrochemical (reduction potentials) properties were determined and compared within the series and with compounds that did not contain a donor moiety. The ICT efficiency correlated well with both the electron-deficient character of the core and the Hammett substituent constants σp. The most efficient ICT was observed for the core with the most electron-accepting substituent (COOBu), and the lowest ICT efficiency was detected for the least electron-deficient core (substituted by OBu). Titration of DMSO solutions of target compounds with H2SO4 indicated that basicity of the azomethine bridges was largely influenced by the character of the peripheral substituents while the dialkylamino donor center remained nearly unaffected. Furthermore, protonation of the donor nitrogen caused partial restoration of the fluorescence quantum yield (increase up to 90 times) due to blocking of ICT. The results implied that the ICT efficiency was strongly dependent on the electron-accepting properties of the core whose properties can be readily affected by suitable selection of peripheral substituents. PMID:25782137

  10. The roles of polycarboxylates in Cr(VI)/sulfite reaction system: Involvement of reactive oxygen species and intramolecular electron transfer.

    PubMed

    Jiang, Bo; Wang, Xianli; Liu, Yukun; Wang, Zhaohui; Zheng, Jingtang; Wu, Mingbo

    2016-03-01

    In this study, the effects of polycarboxylates on both Cr(VI) reduction and S(IV) consumption in Cr(VI)/S(IV) system was investigated in acidic solution. Under aerobic condition, the productions of reactive oxygen species (ROS), i.e., SO4(-) and OH, have been confirmed in S(IV) reducing Cr(VI) process by using electron spin resonance and fluorescence spectrum techniques, leading to the excess consumption of S(IV). However, when polycarboxylates (oxalic, citric, malic and tartaric acid) were present in Cr(VI)/S(IV) system, the affinity of polycarboxylates to CrSO6(2-) can greatly promote the reduction of Cr(VI) via expanding the coordination of Cr(VI) species from tetrahedron to hexahedron. Besides, as alternatives to S(IV), these polycarboxylates can also act as electron donors for Cr(VI) reduction via intramolecular electron transfer reaction, which is dependent on the energies of the highest occupied molecular orbital of these polycarboxylates. Notably, the variant electron donating capacity of these polycarboxylates resulted in different yield of ROS and therefore the oxidation efficiencies of other pollutants, e.g., rhodamine B and As(III). Generally, this study does not only shed light on the mechanism of S(IV) reducing Cr(VI) process mediated by polycarboxylates, but also provides an escalated, cost-effective and green strategy for the remediation of Cr(VI) using sulfite as a reductant. PMID:26610099

  11. Carbon nanotube intramolecular junctions

    NASA Astrophysics Data System (ADS)

    Yao, Zhen; Postma, Henk W. Ch.; Balents, Leon; Dekker, Cees

    1999-11-01

    The ultimate device miniaturization would be to use individual molecules as functional devices. Single-wall carbon nanotubes (SWNTs) are promising candidates for achieving this: depending on their diameter and chirality, they are either one-dimensional metals or semiconductors. Single-electron transistors employing metallic nanotubes and field-effect transistors employing semiconducting nanotubes have been demonstrated. Intramolecular devices have also been proposed which should display a range of other device functions. For example, by introducing a pentagon and a heptagon into the hexagonal carbon lattice, two tube segments with different atomic and electronic structures can be seamlessly fused together to create intramolecular metal-metal, metal-semiconductor, or semiconductor-semiconductor junctions. Here we report electrical transport measurements on SWNTs with intramolecular junctions. We find that a metal-semiconductor junction behaves like a rectifying diode with nonlinear transport characteristics that are strongly asymmetric with respect to bias polarity. In the case of a metal-metal junction, the conductance appears to be strongly suppressed and it displays a power-law dependence on temperatures and applied voltage, consistent with tunnelling between the ends of two Luttinger liquids. Our results emphasize the need to consider screening and electron interactions when designing and modelling molecular devices. Realization of carbon-based molecular electronics will require future efforts in the controlled production of these intramolecular nanotube junctions.

  12. Guidelines for Acceptable Electronic Communication with Students

    ERIC Educational Resources Information Center

    Todoric, Mary E.

    2011-01-01

    Rarely does a day go by when one doesn't hear or read something relating to digital communication and school. Whether it's referencing cell phones, email, Facebook, texting, blogs, or Twitter, this constant barrage of messages in the media makes it clear that electronic communications are in the forefront of students' lives. They are also an…

  13. Electronic Subsystems For Laser Communication System

    NASA Technical Reports Server (NTRS)

    Long, Catherine; Maruschak, John; Patschke, Robert; Powers, Michael

    1992-01-01

    Electronic subsystems of free-space laser communication system carry digital signals at 650 Mb/s over long distances. Applicable to general optical communications involving transfer of great quantities of data, and transmission and reception of video images of high definition.

  14. Quantitative analysis of intramolecular exciplex and electron transfer in a double-linked zinc porphyrin-fullerene dyad.

    PubMed

    Al-Subi, Ali Hanoon; Niemi, Marja; Tkachenko, Nikolai V; Lemmetyinen, Helge

    2012-10-01

    Photoinduced charge transfer in a double-linked zinc porphyrin-fullerene dyad is studied. When the dyad is excited at the absorption band of the charge-transfer complex (780 nm), an intramolecular exciplex is formed, followed by the complete charge separated (CCS) state. By analyzing the results obtained from time-resolved transient absorption and emission decay measurements in a range of solvents with different polarities, we derived a dependence between the observable lifetimes and internal parameters controlling the reaction rate constants based on the semiquantum Marcus electron-transfer theory. The critical value of the solvent polarity was found to be ε(r) ≈ 6.5: in solvents with higher dielectric constants, the energy of the CCS state is lower than that of the exciplex and the relaxation takes place via the CCS state predominantly, whereas in solvents with lower polarities the energy of the CCS state is higher and the exciplex relaxes directly to the ground state. In solvents with moderate polarities the exciplex and the CCS state are in equilibrium and cannot be separated spectroscopically. The degree of the charge shift in the exciplex relative to that in the CCS state was estimated to be 0.55 ± 0.02. The electronic coupling matrix elements for the charge recombination process and for the direct relaxation of the exciplex to the ground state were found to be 0.012 ± 0.001 and 0.245 ± 0.022 eV, respectively. PMID:22958061

  15. Transition Metal Donor-Peptide-Acceptor Complexes: From Intramolecular Electron Transfer Reactions to the Study of Reactive Intermediates

    SciTech Connect

    Isied, Stephan S.

    2003-03-11

    The trans-polyproline (PII) oligomers (Figure 1) are unusually rigid peptide structures which have been extensively studied by our group for peptide mediated intramolecular electron transfer (ET) at long distances. We have previously studied ET across a series of metal ion donor (D) acceptor (A) oligoproline peptides with different distances, driving forces and reorganizational energies. The majority of these experiments involve generating the ET intermediate using pulse radiolysis methods, although more recently photochemical methods are also used. Results of these studies showed that ET across peptides can vary by more than twelve orders of magnitude. Using ruthenium bipyridine donors, ET reaction rate constants across several proline residues (n = 4 - 9) occurred in the millisecond (ms) to {micro}s timescale, thus limiting the proline peptide conformational motions to only minor changes (far smaller than the large changes that occur on the ms to sec timescale, such as trans to cis proline isomerization). The present report describes our large data base of experimental results for D-peptide-A complexes in terms of a model where the involvement of both superexchange and hopping (hole and electron) mechanisms account for the long range ET rate constants observed. Our data shows that the change from superexchange to hopping mechanisms occurs at different distances depending on the type of D and A and their interactions with the peptides. Our model is also consistent with generalized models for superexchange and hopping which have been put forward by a number of theoretical groups to account for long range ET phenomena.

  16. On the existence of intramolecular one-electron Be-Be bonds.

    PubMed

    Brea, Oriana; Mó, Otilia; Yáñez, Manuel; Alkorta, Ibon; Elguero, José

    2016-08-11

    Although the Be-Be bond is extremely weak in Be2 dimers, we have shown that rather stable Be-Be one-electron sigma bonds are formed upon electron attachment to 1,8-diBeX-naphthalene derivatives. Wavefunction analyses corroborate the formation of Be-Be covalent linkages in which the extra electron is accommodated between the Be atoms as reflected in the dramatic shortening of the Be-Be distance with respect to the corresponding neutral molecule. PMID:27398934

  17. Reaction electronic flux and its role in DNA intramolecular proton transfers.

    PubMed

    Durán, Rocío; Vöhringer-Martinez, Esteban; Toro-Labbé, Alejandro; Herrera, Bárbara

    2016-06-01

    Proton transfer reactions present a key step in many biological and chemical processes. Here, we focused on the electronic changes in the proton transfer reactions of the four DNA bases. In combination with the previous structural analysis the reaction electronic flux together with local descriptors as the Hirshfeld-I charges allow us to identify chemical events and rationalize the underlying reaction mechanism. Our results show that imine-enamine in adenine and citosyne, and keto-enol tautomerizations in thymine and guanine have different reaction mechanisms. The former involve net structural rearrangements driven by favoured electrostatic interactions between the proton and the acceptor atom whereas the keto-enol tautomerizations require electronic changes reflected in the reaction electronic flux and changes in the NBO bond orders which favour the proton transfer reaction. PMID:27256316

  18. Peroxidase activity stabilization of cytochrome P450(BM3) by rational analysis of intramolecular electron transfer.

    PubMed

    Vidal-Limón, Abraham; Águila, Sergio; Ayala, Marcela; Batista, Cesar V; Vazquez-Duhalt, Rafael

    2013-05-01

    Combined quantum mechanical and molecular mechanical (QM/MM) calculations were used to explore the electron pathway involved in the suicide inactivation of cytochrome P450BM3 from Bacillus megaterium. The suicide inactivation is a common phenomenon observed for heme peroxidases, in which the enzyme is inactivated as a result of self-oxidation mediated by highly oxidizing enzyme intermediates formed during the catalytic cycle. The selected model was a mutant comprising only the heme domain (CYPBM3 21B3) that had been previously evolved to efficiently catalyze hydroxylation reactions with hydrogen peroxide (H2O2) as electron acceptor. An extensive mapping of residues involved in electron transfer routes was obtained from density functional calculations on activated heme (i.e. Compound I) and selected amino acid residues. Identification of oxidizable residues (electron donors) was performed by selectively activating/deactivating different quantum regions. This method allowed a rational identification of key oxidizable targets in order to replace them for less oxidizable residues by site-directed mutagenesis. The residues W96 and F405 were consistently predicted by the QM/MM electron pathway to hold high spin density; single and double mutants of P450BM3 on these positions (W96A, F405L, W96A/F405L) resulted in a more stable variants in the presence of hydrogen peroxide, displaying a similar reaction rate than P450BM3 21B3. Furthermore, mass spectrometry confirmed these oxidation sites and corroborated the possible routes described by QM/MM electron transfer (ET) pathways. PMID:23425936

  19. Computational methods for intramolecular electron transfer in a ferrous-ferric iron complex.

    PubMed

    Zarzycki, Piotr; Kerisit, Sebastien; Rosso, Kevin

    2011-09-01

    The limitations of common theoretical and molecular computational approaches for predicting electron transfer quantities were assessed, using an archetypal bridged ferrous-ferric electron transfer system in aqueous solution. The basis set effect on the magnitude of the electronic coupling matrix element computed using the quasi-diabatic method was carefully examined, and it was found that the error related to a poor basis set could exceed the thermal energy at room temperature. A range of approaches to determining the external (solvent) reorganization energy were also investigated. Significant improvements from the Marcus continuum model can be obtained by including dipolar Born-Kirkwood-Onsager correction. In this regard, we also found that Klamt's Conductor-Like Screening Model (COSMO) yields estimations of the external reorganization energy similar to those obtained with explicit solvent molecular dynamics simulations if the fast-frequency modes are neglected, which makes it an attractive alternative to laborious umbrella sampling simulations. By using the COSMO model, we also confirm that a decrease in curvature of the potential energy surface is a manifestation of the dielectric saturation observed in the first solvation layer. The linearity of solvent response to the charge redistribution was assessed by analyzing the energy gap autocorrelation function as well as the solvent density and dipole moment fluctuations. Molecular dynamics was also used to evaluate the sign and magnitude of the solvent reorganization entropy and to determine its effect on the predicted electron transfer rate. Finally, we present a simple way of estimating the vibration frequency along the reaction coordinate, which also enables prediction of the mass-dependent isotopic signature of electron transfer reactions. PMID:21696749

  20. Computational methods for intramolecular electron transfer in a ferrous-ferric iron complex

    SciTech Connect

    Zarzycki, Piotr P.; Kerisit, Sebastien N.; Rosso, Kevin M.

    2011-07-29

    The limitations of common theoretical and molecular computational approaches for predicting electron transfer quantities were assessed, using an archetypal bridged ferrous-ferric electron transfer system in aqueous solution. The basis set effect on the magnitude of the electronic coupling matrix element computed using the quasi-diabatic method was carefully examined, and it was found that the error related to a poor basis set could exceed the thermal energy at room temperature. A range of approaches to determining the external (solvent) reorganization energy were also investigated. Significant improvements from the Marcus continuum model can be obtained by including dipolar Born-Kirkwood-Onsager correction. In this regard we also found that Klamt’s Conductor-Like Screening Model (COSMO) yields estimations of the external reorganization energy similar to those obtained with explicit solvent molecular dynamics simulations, if the fast-frequency modes are neglected, which makes it an attractive alternative to laborious umbrella sampling simulations. As expected, dielectric saturation observed in the first solvation shell decreases the curvature of the potential energy surface, but it nonetheless remains a quadratic function of the reaction coordinate. The linearity of solvent response to the charge redistribution was assessed by analyzing the energy gap autocorrelation function as well as the solvent density and dipole moment fluctuations. Molecular dynamics was also used to evaluate the sign and magnitude of the solvent reorganization entropy, to determine its effect on the predicted electron transfer rate. Finally, we present a simple way of estimating the vibration frequency along the reaction coordinate, which also enables prediction of the mass dependent isotopic signature of electron-transfer reactions.

  1. Hole- and electron-vibrational couplings in oligoacene crystals: intramolecular contributions.

    PubMed

    Coropceanu, V; Malagoli, M; da Silva Filho, D A; Gruhn, N E; Bill, T G; Brédas, J L

    2002-12-30

    The hole-vibrational coupling is reported for anthracene, tetracene, and pentacene on the basis of a joint experimental and theoretical study of ionization spectra using high-resolution gas-phase photoelectron spectroscopy and first-principles correlated quantum-mechanical calculations. The hole-vibrational coupling is found to be significantly smaller than the electron-vibrational coupling in the case of these oligomers; however, both quantities are predicted to converge to the same value when increasing the chain length. PMID:12513217

  2. A Binuclear 1,1'-Bis(boratabenzene) Complex: Unprecedented Intramolecular Metal-Metal Communication through a B-B Bond.

    PubMed

    Braunschweig, Holger; Demeshko, Serhiy; Ewing, William C; Krummenacher, Ivo; Macha, Bret B; Mattock, James D; Meyer, Franc; Mies, Jan; Schäfer, Marius; Vargas, Alfredo

    2016-06-27

    We report the synthesis of the first 1,1'-bis(boratabenzene) species by tetrabromodiborane(4)-induced ring-expansion reactions of cobaltocene. Six equivalents of cobaltocene are required as the species plays the dual role of reagent and reductant to yield [{(η(5) -C5 H5 )Co}2 {μ:η(6) ,η(6) -(BC5 H5 )2 }]. The formally dianionic bis(boratabenzene) moiety with a boron-boron single bond can be viewed as a symmetric dimer of the parent boratabenzene anion as well as the first example of a diboron analogue of biphenyl. The solution electrochemistry of the bimetallic complex shows four stepwise redox events, indicating significant intramolecular interaction between the cobalt ions across the 1,1'-bis(boratabenzene) unit. The magnetic properties, as investigated by variable-temperature SQUID magnetometry, reveal weak intramolecular antiferromagnetic interactions. Density functional theory calculations support the experimental results and add insight into the various electronic states of the complex. PMID:27240267

  3. An Electronic Patient Risk Communication Board

    PubMed Central

    Ohashi, Kumiko; Caligtan, Christine A.; Benoit, Angela N.; Breydo, Eugene M.; Carroll, Diane L.; Keohane, Carol A.; Bates, David W.; Dykes, John S.; Dykes, Patricia C.

    2012-01-01

    Communication failures have been identified as the root cause of the majority of medical malpractice claims and patient safety violations. We believe it is essential to share key patient risk information with healthcare team members at the patient’s bedside. In this study, we developed an electronic Patient Risk Communication Board (ePRCB) to assist in bridging the communication gap between all health care team members. The goal of the ePRCB is to effectively communicate the patient’s key risk factors, such as a fall risk or risk of aspiration, to the healthcare team and to reduce adverse events caused by communication failures. The ePRCB will transmit patient risk information and tailored interventions with easy-to-understand icons on an LCD screen at the point of care. A set of patient risk reminder icons was developed and validated by focus groups. We used the results of the evaluation to refine the icons for the ePRCB. PMID:24199109

  4. Teaching Electronic Health Record Communication Skills.

    PubMed

    Palumbo, Mary Val; Sandoval, Marie; Hart, Vicki; Drill, Clarissa

    2016-06-01

    This pilot study investigated nurse practitioner students' communication skills when utilizing the electronic health record during history taking. The nurse practitioner students (n = 16) were videotaped utilizing the electronic health record while taking health histories with standardized patients. The students were videotaped during two separate sessions during one semester. Two observers recorded the time spent (1) typing and talking, (2) typing only, and (3) looking at the computer without talking. Total history taking time, computer placement, and communication skills were also recorded. During the formative session, mean history taking time was 11.4 minutes, with 3.5 minutes engaged with the computer (30.6% of visit). During the evaluative session, mean history taking time was 12.4 minutes, with 2.95 minutes engaged with the computer (24% of visit). The percentage of time individuals spent changed over the two visits: typing and talking, -3.1% (P = .3); typing only, +12.8% (P = .038); and looking at the computer, -9.6% (P = .039). This study demonstrated that time spent engaged with the computer during a patient encounter does decrease with student practice and education. Therefore, students benefit from instruction on electronic health record-specific communication skills, and use of a simple mnemonic to reinforce this is suggested. PMID:27058674

  5. Intramolecular structure and dynamics of mequinol and guaiacol in the gas phase: Rotationally resolved electronic spectra of their S{sub 1} states

    SciTech Connect

    Ruiz-Santoyo, José Arturo; Rodríguez-Matus, Marcela; Álvarez-Valtierra, Leonardo E-mail: gmerino@mda.cinvestav.mx; Cabellos, José Luis; Merino, Gabriel E-mail: gmerino@mda.cinvestav.mx; Yi, John T.; Pratt, David W.; Schmitt, Michael

    2015-09-07

    The molecular structures of guaiacol (2-methoxyphenol) and mequinol (4-methoxyphenol) have been studied using high resolution electronic spectroscopy in a molecular beam and contrasted with ab initio computations. Mequinol exhibits two low frequency bands that have been assigned to electronic origins of two possible conformers of the molecule, trans and cis. Guaiacol also shows low frequency bands, but in this case, the bands have been assigned to the electronic origin and vibrational modes of a single conformer of the isolated molecule. A detailed study of these bands indicates that guaiacol has a vibrationally averaged planar structure in the ground state, but it is distorted along both in-plane and out-of-plane coordinates in the first electronically excited state. An intramolecular hydrogen bond involving the adjacent   –OH and   –OCH{sub 3} groups plays a major role in these dynamics.

  6. Replacing the Tin Can: Creating an Effective Electronic Communication Environment.

    ERIC Educational Resources Information Center

    Powers, Susan M.; Dutt-Doner, Karen M.

    Electronic communication tools may have more in common with the old communication game where tin cans were connected by a string than with traditional classroom communication. The charge is to find ways to make the communication more like, and possibly better, than effective classroom communication. Creating a firm foundation for successful…

  7. Excited-state intramolecular hydrogen transfer (ESIHT) of 1,8-dihydroxy-9,10-anthraquinone (DHAQ) characterized by ultrafast electronic and vibrational spectroscopy and computational modeling.

    PubMed

    Mohammed, Omar F; Xiao, Dequan; Batista, Victor S; Nibbering, Erik T J

    2014-05-01

    We combine ultrafast electronic and vibrational spectroscopy and computational modeling to investigate the photoinduced excited-state intramolecular hydrogen-transfer dynamics in 1,8-dihydroxy-9,10-anthraquinone (DHAQ) in tetrachloroethene, acetonitrile, dimethyl sulfoxide, and methanol. We analyze the electronic excited states of DHAQ with various possible hydrogen-bonding schemes and provide a general description of the electronic excited-state dynamics based on a systematic analysis of femtosecond UV/vis and UV/IR pump-probe spectroscopic data. Upon photoabsorption at 400 nm, the S2 electronic excited state is initially populated, followed by a rapid equilibration within 150 fs through population transfer to the S1 state where DHAQ exhibits ESIHT dynamics. In this equilibration process, the excited-state population is distributed between the 9,10-quinone (S2) and 1,10-quinone (S1) states while undergoing vibrational energy redistribution, vibrational cooling, and solvation dynamics on the 0.1-50 ps time scale. Transient UV/vis pump-probe data in methanol also suggest additional relaxation dynamics on the subnanosecond time scale, which we tentatively ascribe to hydrogen bond dynamics of DHAQ with the protic solvent, affecting the equilibrium population dynamics within the S2 and S1 electronic excited states. Ultimately, the two excited singlet states decay with a solvent-dependent time constant ranging from 139 to 210 ps. The concomitant electronic ground-state recovery is, however, only partial because a large fraction of the population relaxes to the first triplet state. From the similarity of the time scales involved, we conjecture that the solvent plays a crucial role in breaking the intramolecular hydrogen bond of DHAQ during the S2/S1 relaxation to either the ground or triplet state. PMID:24684387

  8. Kinetics of inter- and intramolecular electron transfer of Pseudomonas nautica cytochrome cd1 nitrite reductase: regulation of the NO-bound end product.

    PubMed

    Lopes, H; Besson, S; Moura, I; Moura, J J

    2001-01-01

    The intermolecular electron transfer kinetics between nitrite reductase (NiR, cytochrome cd1) isolated from Pseudomonas nautica and three cytochromes c isolated from the same strain, as well as the intramolecular electron transfer between NiR heme c and NiR heme d1, were investigated by cyclic voltammetry. All cytochromes (cytochrome c552, cytochrome c553 and cytochrome C553(548)) exhibited well-behaved electrochemistry. The individual diffusion coefficients and mid-point redox potentials were determined. Under the experimental conditions, only cytochrome c552 established a rapid electron transfer with NiR. At acidic pH, the intermolecular electron transfer (cytochrome c(552red)-->NiR heme cox) is a second-order reaction with a rate constant (k2) of 4.1+/-0.1x10(5) M(-1) s(-1) (pH=6.3 and 100 mM NaCl). Under these conditions, the intermolecular reaction represents the rate-limiting step. A minimum estimate of 33 s(-1) could be determined for the first-order rate constant (k1) of the intramolecular electron transfer reaction NiR heme c(red)-->NiR heme d1ox. The pH dependence of k2 values was investigated at pH values ranging from 5.8 to 8.0. When the pH is progressively shifted towards basic values, the rate constant of the intramolecular electron transfer reaction NiR heme c(red)-->NiR heme d1ox decreases gradually to a point where it becomes rate limiting. At pH 8.0 we determined a value of 1.4+/-0.7 s(-1), corresponding to a k2 value of 2.2+/-1.1x10(4) M(-1) s(-1) for the intermolecular step. The physiological relevance of these results is discussed with a particular emphasis on the proposed mechanism of "dead-end product" formation. PMID:11191223

  9. The whole of intramolecular H-bonding in the isolated DNA nucleoside thymidine. AIM electron density topological study

    NASA Astrophysics Data System (ADS)

    Yurenko, Yevgen P.; Zhurakivsky, Roman O.; Samijlenko, Svitlana P.; Ghomi, Mahmoud; Hovorun, Dmytro M.

    2007-10-01

    Based on comprehensive conformational analysis at the DFT B3LYP/6-31G(d,p) level of theory [Ye.P. Yurenko et al., J. Phys. Chem. B, 111 (2007) 9655] 13 types of intramolecular hydrogen bonds (171 in total number, from 1 to 3 H-bonds per conformer) were identified in the 92 allowed conformers of isolated thymidine, a DNA canonical nucleoside. Weak interactions CH⋯ O, OH⋯ HC and CH⋯ HC were analyzed by all the Koch and Popelier criteria of H-bonding. Quite satisfactory linear correlation was found between Grabowski complex measure of H-bond strength Δcom and Iogansen H-bond energy -Δ H for 17 OH⋯O hydrogen bonds.

  10. Thorium and uranium redox-active ligand complexes; reversible intramolecular electron transfer in U(dpp-BIAN)2/ U(dpp-BIAN)2(THE)

    SciTech Connect

    Schelter, Eric John; Wu, Ruilian; Scott, Brian L; Thompson, Joe D; Batista, Enrique R; Morris, David E; Kiplinger, Jaqueline L

    2008-01-01

    Actinide complexes of the redox-active ligand dpp-BIAN{sup 2-} (dpp-BIAN = bis(2,6-diisopropylphenyl)acenaphthylene), An(dpp-BIAN){sub 2}(THF){sub n} (An = Th, n = 1; An = U, n = 0, 1) have been prepared. Solid-state magnetic and single-crystal X-ray data for U(dpp-BIAN){sub 2}(THF){sub n} show when n = 0, the complex exists in an f{sup 2}-{pi}*{sup 4} configuration; whereas an intramolecular electron transfer occurs for n = 1, resulting in an f{sup 3}-{pi}*{sup 3} ground configuration. The magnetic data also indicate that interconversion between the two forms of the complex is possible, limited only by the ability of THF vapor to penetrate the solid on cooling of the sample. Spectroscopic data indicate the complex exists solely in the f{sup 2}-{pi}*{sup 4} form in solution, evidenced by the appearance of only small changes in the electronic absorption spectra of the U(dpp-BIAN){sub 2} complex on titration with THF and by measurement of the solution magnetic moment m d{sub 8}-tetrahydrofuran using Evans method. Electrochemistry of the complexes is reported, with small differences observed in wave potentials between metals and in the presence of THF. These data represent the first example of a well-defined, reversible intramolecular electron transfer in an f-element complex and the second example of oxidation state change through dative interaction with a metal ion.

  11. Fluorinated Dodecaphenylporphyrins: Synthetic and Electrochemical Studies Including the First Evidence of Intramolecular Electron Transfer Between an Fe(II) Porphyrin -Anion Radical and an Fe(I) Porphyrin

    SciTech Connect

    D'Souza, F.; Forsyth, T.P.; Fukuzumi, S.; Kadish, K.M.; Krattinger, B.; Lin, M.; Medforth, C.J.; Nakanishi, I.; Nurco, D.J.; Shelnutt, J.A.; Smith, K.M.; Van Caemelbecke, E.

    1998-10-19

    Dodecaphenylporphyrins with varying degrees of fluorination of the peripheral phenyl rings (FXDPPS) were synthesized as model compounds for studying electronic effects in nonplan~ porphyrins, and detailed electrochemical studies of the chloroiron(HI) complexes of these compounds were undertaken. The series of porphyrins, represented as FeDPPCl and as FeFXDPPCl where x = 4, 8 (two isomers), 12, 20,28 or 36, could be reversibly oxidized by two electrons in dichloromethane to give n-cation radicals and n-dications. All of the compounds investigated could also be reduced by three electrons in benzonitrile or pyridine. In benzonitrile, three reversible reductions were observed for the unfluorinated compound FeDPPC1, whereas the FeFXDPPCl complexes generally exhibited irreversible first and second reductions which were coupled to chemical reactions. The chemical reaction associated with the first reduction involved a loss of the chloride ion after generation of Fe FXDPPC1. The second chemical reaction involved a novel intramolecular electron transfer between the initially generated Fe(H) porphyrin n-anion radical and the final Fe(I) porphyrin reduction product. In pyridine, three reversible one electron reductions were observed with the second reduction affording stable Fe(II) porphyrin o - anion radicals for ail of the complexes investigated.

  12. Fast intramolecular electron transfer and dual fluorescence. Configurational change of the amino nitrogen (pyramidal{yields}planar)

    SciTech Connect

    Haar, Th. von der; Hebecker, A.; Il'Ichev, Yu.; Kuehnle, W.; Zachariasse, K. A.

    1996-04-01

    The fast excited state intramolecular charge transfer (ICT) and dual fluorescence observed with several 4-aminobenzonitriles is discussed. It is shown that the magnitude of the energy gap between the two lowest excited states determines the occurrence or absence of ICT. The photophysical behavior of a series of four 4-aminobenzonitriles in which the amino nitrogen atom is part of a four- to seven-membered heterocyclic ring, P4C to P7C, is studied by using time-resolved fluorescence measurements. The ICT rate constant strongly decreases with decreasing ring size. With P4C in diethyl ether ICT does not occur. This is attributed to the increase of the amino nitrogen inversion barrier with decreasing ring size. The change of the amino nitrogen from pyramidal to planar is considered to be an important reaction coordinate. The photophysics of the 4-aminobenzonitriles is different from that of other ICT systems such as donor/acceptor-substituted stilbenes and 9,9'-bianthryl, which are governed by the charge distribution and macroscopic Coulombic interaction in their CT states.

  13. Intramolecular charge transfer photoemission of a silicon-based copolymer containing carbazole and divinylbenzene chromophores. Electron transfer across silicon bridges.

    PubMed

    Bayda, Malgorzata; Ludwiczak, Monika; Hug, Gordon L; Majchrzak, Mariusz; Marciniec, Bogdan; Marciniak, Bronislaw

    2014-07-01

    A new copolymer consisting of N-isopropylcarbazole/dimethylsilylene bridge/divinylbenzene units was synthesized and characterized. Dual fluorescence was observed in this copolymer in polar solvents. The absence of the second band at the lower transition energy of the two emission maxima in nonpolar solvents and the quantitative correlation of the lower-energy emission band maxima with solvent polarity indicate that the lower-energy emission band arises from an intramolecular charge transfer (ICT) state. A series of model compounds was synthesized to investigate the source of the charge transfer. It was found that the Si-bridged dyad with a single N-isopropylcarbazole and a single divinylbenzene was the minimum structure necessary to observe dual luminescence. The lack of dual luminescence in low-temperature glasses indicates that the ICT requires a conformation change in the copolymer. Analogous behavior in the Si-bridged dyad suggests that the ICT in the copolymer is across the silicon bridge. Results from time-resolved luminescence measurements with picosecond and subnanosecond excitation were used to support the thesis that twisted charge-transfer states are the likely source of the observed dual luminescence. PMID:24901805

  14. The Impact of Electronic Communication Technology on Written Language

    ERIC Educational Resources Information Center

    Hamzah, Mohd. Sahandri Gani B.; Ghorbani, Mohd. Reza; Abdullah, Saifuddin Kumar B.

    2009-01-01

    Communication technology is changing things. Language is no exception. Some language researchers argue that language is deteriorating due to increased use in electronic communication. The present paper investigated 100 randomly selected electronic mails (e-mails) and 50 short messaging system (SMS) messages of a representative sample of…

  15. The Effects of Electronic Communication on American Sign Language

    ERIC Educational Resources Information Center

    Schneider, Erin; Kozak, L. Viola; Santiago, Roberto; Stephen, Anika

    2012-01-01

    Technological and language innovation often flow in concert with one another. Casual observation by researchers has shown that electronic communication memes, in the form of abbreviations, have found their way into spoken English. This study focuses on the current use of electronic modes of communication, such as cell smartphones, and e-mail, and…

  16. The effects of 5-7 defects on the mechanical characteristics of carbon nanotubes intramolecular junctions and their influences on electronic properties

    NASA Astrophysics Data System (ADS)

    Lee, Wen-Jay; Chang, Jee-Gong; Wang, Yeng-Tseng; Su, Wan-Sheng

    2012-02-01

    This study utilizes molecular dynamics simulations and first-principles techniques to investigate mechanical and electronic properties of the single-walled carbon nanotube (SWCNT) intramolecular junctions (IMJs). Results show that the mechanical behaviors are mainly affected by the diameter of thinner segment of two composed tubes, whereas are barely able to be influenced by the number of 5-7 defects in the interface region. With applied compression, the yielding stress and Young's modulus of the SWCNT IMJs are found to be strongly associated with the orientation of two contacted heptagon rings where their ordering values are vertical > tilted > parallel to the axial direction. Under applied tensile, a lowest value in the yielding stress and Young's modulus is found on the parallel status, but the other two reveal alternating relations. Moreover, the magnitude of the stress amplitude is proportional to the Young's modulus and yielding stress and the buckling location is shown to be dependence on different orientations of two contacted heptagon rings. Finally, our first-principles calculations indicated that the considered SWCNT (5,0)/(8,0) IMJs at a certain length with different distributions of 5-7 defects on the tube wall exhibit diverse electronic properties, such as the changes of the density of states and modulation of energy gap. With increasing length, the numbers of states near the Fermi level region increase significantly and the energy gap tends to shrink as well.

  17. 12 CFR 609.950 - Electronic communications.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) Communications with consumers. E-SIGN and Federal Reserve Board Regulations B, M, and Z (12 CFR parts 202, 213... Reserve Board Regulation B (12 CFR part 202) do not apply to your communications with parties other than consumers. (Federal Reserve Board Regulations M and Z (12 CFR parts 213 and 226) apply to consumers...

  18. 12 CFR 609.950 - Electronic communications.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) Communications with consumers. E-SIGN and Federal Reserve Board Regulations B, M, and Z (12 CFR parts 202, 213... Reserve Board Regulation B (12 CFR part 202) do not apply to your communications with parties other than consumers. (Federal Reserve Board Regulations M and Z (12 CFR parts 213 and 226) apply to consumers...

  19. 12 CFR 609.950 - Electronic communications.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) Communications with consumers. E-SIGN and Federal Reserve Board Regulations B, M, and Z (12 CFR parts 202, 213... Reserve Board Regulation B (12 CFR part 202) do not apply to your communications with parties other than consumers. (Federal Reserve Board Regulations M and Z (12 CFR parts 213 and 226) apply to consumers...

  20. 12 CFR 609.950 - Electronic communications.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) Communications with consumers. E-SIGN and Federal Reserve Board Regulations B, M, and Z (12 CFR parts 202, 213... Reserve Board Regulation B (12 CFR part 202) do not apply to your communications with parties other than consumers. (Federal Reserve Board Regulations M and Z (12 CFR parts 213 and 226) apply to consumers...

  1. 12 CFR 609.950 - Electronic communications.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...) Communications with consumers. E-SIGN and Federal Reserve Board Regulations B, M, and Z (12 CFR parts 202, 213... Reserve Board Regulation B (12 CFR part 202) do not apply to your communications with parties other than consumers. (Federal Reserve Board Regulations M and Z (12 CFR parts 213 and 226) apply to consumers...

  2. Technical Communicator: A New Model for the Electronic Resources Librarian?

    ERIC Educational Resources Information Center

    Hulseberg, Anna

    2016-01-01

    This article explores whether technical communicator is a useful model for electronic resources (ER) librarians. The fields of ER librarianship and technical communication (TC) originated and continue to develop in relation to evolving technologies. A review of the literature reveals four common themes for ER librarianship and TC. While the…

  3. 78 FR 1247 - Certain Electronic Devices, Including Wireless Communication Devices, Tablet Computers, Media...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-08

    ... COMMISSION Certain Electronic Devices, Including Wireless Communication Devices, Tablet Computers, Media... United States after importation of certain electronic devices, including wireless communication devices... importation of certain electronic devices, including wireless communication devices, tablet computers,...

  4. 78 FR 38361 - Certain Portable Electronic Communications Devices, Including Mobile Phones and Components...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-26

    ... COMMISSION Certain Portable Electronic Communications Devices, Including Mobile Phones and Components Thereof... States after importation of certain portable electronic ] communications devices, including mobile phones... importation of certain portable electronic communications devices, including mobile phones and...

  5. Secure electronic commerce communication system based on CA

    NASA Astrophysics Data System (ADS)

    Chen, Deyun; Zhang, Junfeng; Pei, Shujun

    2001-07-01

    In this paper, we introduce the situation of electronic commercial security, then we analyze the working process and security for SSL protocol. At last, we propose a secure electronic commerce communication system based on CA. The system provide secure services such as encryption, integer, peer authentication and non-repudiation for application layer communication software of browser clients' and web server. The system can implement automatic allocation and united management of key through setting up the CA in the network.

  6. Patient–physician communication regarding electronic cigarettes

    PubMed Central

    Steinberg, Michael B.; Giovenco, Daniel P.; Delnevo, Cristine D.

    2015-01-01

    Introduction Smokers are likely asking their physicians about the safety of e-cigarettes and their potential role as a cessation tool; however, the research literature on this communication is scant. A pilot study of physicians in the United States was conducted to investigate physician–patient communication regarding e-cigarettes. Methods A total of 158 physicians were recruited from a direct marketing e-mail list and completed a short, web-based survey between January and April 2014. The survey addressed demographics, physician specialty, patient–provider e-cigarette communication, and attitudes towards tobacco harm reduction. Results Nearly two-thirds (65%) of physicians reported being asked about e-cigarettes by their patients, and almost a third (30%) reported that they have recommended e-cigarettes as a smoking cessation tool. Male physicians were significantly more likely to endorse a harm reduction approach. Discussion Physician communication about e-cigarettes may shape patients' perceptions about the products. More research is needed to explore the type of information that physicians share with their patients regarding e-cigarettes and harm reduction. PMID:26844056

  7. Effects of mutating aromatic surface residues of the heme domain of human sulfite oxidase on its heme midpoint potential, intramolecular electron transfer, and steady-state kinetics.

    PubMed

    Davis, Amanda C; Cornelison, Matthew J; Meyers, Kimberly T; Rajapakshe, Asha; Berry, Robert E; Tollin, Gordon; Enemark, John H

    2013-03-01

    Human sulfite oxidase (hSO), an essential molybdoheme enzyme, catalyzes the oxidation of toxic sulfite to sulfate. The proposed catalytic cycle includes two, one-electron intramolecular electron transfers (IET) between the molybdenum (Mo) and the heme domains. Rapid IET rates are ascribed to conformational changes that bring the two domains into close proximity to one another. Previous studies of hSO have focused on the roles of conserved residues near the Mo active site and on the tether that links the two domains. Here four aromatic surface residues on the heme domain (phenylalanine 57 (F57), phenylalanine 79 (F79), tyrosine 83 (Y83), and histidine 90 (H90)) have been mutated, and their involvement in IET rates, the heme midpoint potential, and the catalytic activity of hSO have been investigated using laser flash photolysis, spectroelectrochemistry, and steady-state kinetics, respectively. The results indicate that the size and hydrophobicity of F57 play an important role in modulating the heme potential and that F57 also affects the IET rates. The data also suggest that important interactions of H90 with a heme propionate group destabilize the Fe(III) state of the heme. The positive charge on H90 at pH ≤ 7.0 may decrease the electrostatic interaction between the Mo and heme domains, thereby decreasing the IET rates of wt hSO at low pH. Lastly, mutations of F79 and Y83, which are located on the surface of the heme domain, but not in direct contact with the heme or the propionate groups, have little effect on either IET or the heme potential. PMID:22975842

  8. Ultrafast photodriven intramolecular electron transfer from an iridium-based water-oxidation catalyst to perylene diimide derivatives

    PubMed Central

    Vagnini, Michael T.; Smeigh, Amanda L.; Blakemore, James D.; Eaton, Samuel W.; Schley, Nathan D.; D’Souza, Francis; Crabtree, Robert H.; Brudvig, Gary W.; Co, Dick T.; Wasielewski, Michael R.

    2012-01-01

    Photodriving the activity of water-oxidation catalysts is a critical step toward generating fuel from sunlight. The design of a system with optimal energetics and kinetics requires a mechanistic understanding of the single-electron transfer events in catalyst activation. To this end, we report here the synthesis and photophysical characterization of two covalently bound chromophore-catalyst electron transfer dyads, in which the dyes are derivatives of the strong photooxidant perylene-3,4:9,10-bis(dicarboximide) (PDI) and the molecular catalyst is the Cp∗Ir(ppy)Cl metal complex, where ppy = 2-phenylpyridine. Photoexcitation of the PDI in each dyad results in reduction of the chromophore to PDI•- in less than 10 ps, a process that outcompetes any generation of 3∗PDI by spin-orbit-induced intersystem crossing. Biexponential charge recombination largely to the PDI-Ir(III) ground state is suggestive of multiple populations of the PDI•--Ir(IV) ion-pair, whose relative abundance varies with solvent polarity. Electrochemical studies of the dyads show strong irreversible oxidation current similar to that seen for model catalysts, indicating that the catalytic integrity of the metal complex is maintained upon attachment to the high molecular weight photosensitizer. PMID:22586073

  9. Length-dependence of intramolecular electron transfer in σ-bonded rigid molecular rods: an ab initio molecular orbital study

    NASA Astrophysics Data System (ADS)

    Pati, Ranjit; Karna, Shashi P.

    2002-01-01

    The dependence of electron transfer (ET) coupling element, VAB, on the length of rigid-rod-like systems consisting of bicyclo[1.1.1]pentane (BCP), cubane (CUB), and bicyclo[2.2.2]octane (BCO) monomers, has been investigated with the use of ab initio Hartree-Fock (HF) method employing Marcus-Hush two-state (TS) model. The value of VAB decreases exponentially with increase in the number of the cage units of the σ-bonded molecules. The calculated decay constant, β, shows good agreement with previously reported data. For molecular length⩾15 Å, the value of VAB becomes negligibly small, suggesting complete suppression of the through bond direct tunneling contribution to ET process.

  10. Intramolecular charge separation and recombination in non-polar environments via long-distance electron transfer through saturated hydrocarbon barriers

    NASA Astrophysics Data System (ADS)

    Warman, John M.; Smit, Kenneth J.; Jonker, Stephan A.; Verhoeven, Jan W.; Oevering, Henk; Kroon, Jan; Paddon-Row, Michael N.; Oliver, Anna M.

    1993-03-01

    Time-resolved microwave conductivity and fluorescence spectroscopy techniques have been used to monitor the kinetics of charge separation and recombination following photo-excitation of donor-spacer-acceptor (DSA) molecules in which the spacer is a rigid saturated hydrocarbon bridge of length varying from 4.6 to 13.5 Å. The solvents used were all completely non-polar saturated hydrocarbons with relative dielectric constants varying from 1.8 to 2.3. The lifetimes of the highly dipolar, charge-separated states formed increase initially with increasing length of the spacer but eventually decrease for distances longer than approximately 9 Å. At that point the lifetime becomes sensitive to the dielectric constant of the medium and the temperature which was varied between 175 and 375 K. At the transition distance delayed donor fluorescence is observed. The results are explained in terms of the decrease in the Coulomb energy with increasing distance which raises the energy level of the charge separated state and eventually brings it close to the energy level of the locally excited donor (LED) state. Under these conditions charge recombination occurs preferentially via the LED state by thermally activated back electron transfer. The enegetics underlying this change in recombination mechanism are discussed.

  11. Project ECHO: Electronic Communications from Halo Orbit

    NASA Technical Reports Server (NTRS)

    Borrelli, Jason; Cooley, Bryan; Debole, Marcy; Hrivnak, Lance; Nielsen, Kenneth; Sangmeister, Gary; Wolfe, Matthew

    1994-01-01

    The design of a communications relay to provide constant access between the Earth and the far side of the Moon is presented. Placement of the relay in a halo orbit about the L2 Earth-Moon Lagrange point allows the satellite to maintain constant simultaneous communication between Earth and scientific payloads on the far side of the Moon. The requirements of NASA's Discovery-class missions adopted and modified for this design are: total project cost should not exceed $150 million excluding launch costs, launch must be provided by Delta-class vehicle, and the satellite should maintain an operational lifetime of 10 to 15 years. The spacecraft will follow a transfer trajectory to the L2 point, after launch by a Delta II 7925 vehicle in 1999. Low-level thrust is used for injection into a stationkeeping-free halo orbit once the spacecraft reaches the L2 point. The shape of this halo orbit is highly elliptical with the maximum excursion from the L2 point being 35000 km. A spun section and despun section connected through a bearing and power transfer assembly (BAPTA) compose the structure of the spacecraft. Communications equipment is placed on the despun section to provide for a stationary dual parabolic offset-feed array antenna system. The dual system is necessary to provide communications coverage during portions of maximum excursion on the halo orbit. Transmissions to the NASA Deep Space Network 34 m antenna include six channels (color video, two voice, scientific data from lunar payloads, satellite housekeeping and telemetry and uplinked commands) using the S- and X-bands. Four radioisotope thermoelectric generators (RTG's) provide a total of 1360 W to power onboard systems and any two of the four Hughes 13 cm ion thrusters at once. Output of the ion thrusters is approximately 17.8 mN each with xenon as the propellant. Presence of torques generated by solar pressure on the antenna dish require the addition of a 'skirt' extending from the spun section of the satellite

  12. Project ECHO: Electronic Communications from Halo Orbit

    NASA Astrophysics Data System (ADS)

    Borrelli, Jason; Cooley, Bryan; Debole, Marcy; Hrivnak, Lance; Nielsen, Kenneth; Sangmeister, Gary; Wolfe, Matthew

    The design of a communications relay to provide constant access between the Earth and the far side of the Moon is presented. Placement of the relay in a halo orbit about the L2 Earth-Moon Lagrange point allows the satellite to maintain constant simultaneous communication between Earth and scientific payloads on the far side of the Moon. The requirements of NASA's Discovery-class missions adopted and modified for this design are: total project cost should not exceed $150 million excluding launch costs, launch must be provided by Delta-class vehicle, and the satellite should maintain an operational lifetime of 10 to 15 years. The spacecraft will follow a transfer trajectory to the L2 point, after launch by a Delta II 7925 vehicle in 1999. Low-level thrust is used for injection into a stationkeeping-free halo orbit once the spacecraft reaches the L2 point. The shape of this halo orbit is highly elliptical with the maximum excursion from the L2 point being 35000 km. A spun section and despun section connected through a bearing and power transfer assembly (BAPTA) compose the structure of the spacecraft. Communications equipment is placed on the despun section to provide for a stationary dual parabolic offset-feed array antenna system. The dual system is necessary to provide communications coverage during portions of maximum excursion on the halo orbit. Transmissions to the NASA Deep Space Network 34 m antenna include six channels (color video, two voice, scientific data from lunar payloads, satellite housekeeping and telemetry and uplinked commands) using the S- and X-bands. Four radioisotope thermoelectric generators (RTG's) provide a total of 1360 W to power onboard systems and any two of the four Hughes 13 cm ion thrusters at once. Output of the ion thrusters is approximately 17.8 mN each with xenon as the propellant. Presence of torques generated by solar pressure on the antenna dish require the addition of a 'skirt' extending from the spun section of the satellite

  13. Communication: Electron ionization of DNA bases

    NASA Astrophysics Data System (ADS)

    Rahman, M. A.; Krishnakumar, E.

    2016-04-01

    No reliable experimental data exist for the partial and total electron ionization cross sections for DNA bases, which are very crucial for modeling radiation damage in genetic material of living cell. We have measured a complete set of absolute partial electron ionization cross sections up to 500 eV for DNA bases for the first time by using the relative flow technique. These partial cross sections are summed to obtain total ion cross sections for all the four bases and are compared with the existing theoretical calculations and the only set of measured absolute cross sections. Our measurements clearly resolve the existing discrepancy between the theoretical and experimental results, thereby providing for the first time reliable numbers for partial and total ion cross sections for these molecules. The results on fragmentation analysis of adenine supports the theory of its formation in space.

  14. Communication: Electron ionization of DNA bases.

    PubMed

    Rahman, M A; Krishnakumar, E

    2016-04-28

    No reliable experimental data exist for the partial and total electron ionization cross sections for DNA bases, which are very crucial for modeling radiation damage in genetic material of living cell. We have measured a complete set of absolute partial electron ionization cross sections up to 500 eV for DNA bases for the first time by using the relative flow technique. These partial cross sections are summed to obtain total ion cross sections for all the four bases and are compared with the existing theoretical calculations and the only set of measured absolute cross sections. Our measurements clearly resolve the existing discrepancy between the theoretical and experimental results, thereby providing for the first time reliable numbers for partial and total ion cross sections for these molecules. The results on fragmentation analysis of adenine supports the theory of its formation in space. PMID:27131520

  15. Intramolecular and nonlinear dynamics

    SciTech Connect

    Davis, M.J.

    1993-12-01

    Research in this program focuses on three interconnected areas. The first involves the study of intramolecular dynamics, particularly of highly excited systems. The second area involves the use of nonlinear dynamics as a tool for the study of molecular dynamics and complex kinetics. The third area is the study of the classical/quantum correspondence for highly excited systems, particularly systems exhibiting classical chaos.

  16. The Elements of Electronic Communication. The Elements of Composition Series.

    ERIC Educational Resources Information Center

    Schultz, Heidi

    Based on the proposition that if people want their electronic messages to get the results they desire, they will need to adopt and practice effective communication strategies, this book introduces strategies that make e-mail messages, Web site text, and newsgroup postings effective. To this end, it teaches how word choice can affect meaning, how…

  17. Electronic Communication between the School and the Home

    ERIC Educational Resources Information Center

    Kosaretskii, S. G.; Chernyshova, D. V.

    2013-01-01

    Improving the involvement of families in the lives of school students in Russia can be achieved through the use of electronic communication, but only if teachers and parents are given the knowledge and motivation that are necessary to make greater use of the Internet.

  18. Expanding Horizons: Electronic Communication and Classroom Teaching in Sociology.

    ERIC Educational Resources Information Center

    Southard, P. A. Dee

    1997-01-01

    Electronic mail, the World Wide Web, and listservs can be used in exercises in undergraduate sociology courses. This article briefly describes "Seminar Sheet," an individual exercise in collecting Web-based information to be shared in the classroom; establishing instructor/student communication through e-mail assignments; and having students…

  19. Electronic Mail in Foreign Language Learning: Communication and Culture.

    ERIC Educational Resources Information Center

    Leh, Amy Sheng-Chieh

    National standards published in 1995 addressed the importance of foreign language education and identified five goal areas: communication, cultures, connections, comparisons, and communities. This study incorporated these five goals and examined the potential of electronic mail in foreign language learning. In addition, it looked at cultural…

  20. Electronics systems test laboratory testing of shuttle communications systems

    NASA Technical Reports Server (NTRS)

    Stoker, C. J.; Bromley, L. K.

    1985-01-01

    Shuttle communications and tracking systems space to space and space to ground compatibility and performance evaluations are conducted in the NASA Johnson Space Center Electronics Systems Test Laboratory (ESTL). This evaluation is accomplished through systems verification/certification tests using orbiter communications hardware in conjunction with other shuttle communications and tracking external elements to evaluate end to end system compatibility and to verify/certify that overall system performance meets program requirements before manned flight usage. In this role, the ESTL serves as a multielement major ground test facility. The ESTL capability and program concept are discussed. The system test philosophy for the complex communications channels is described in terms of the major phases. Results of space to space and space to ground systems tests are presented. Several examples of the ESTL's unique capabilities to locate and help resolve potential problems are discussed in detail.

  1. Radiation-Hardened Electronics for Advanced Communications Systems

    NASA Technical Reports Server (NTRS)

    Whitaker, Sterling

    2015-01-01

    Novel approach enables high-speed special-purpose processors Advanced reconfigurable and reprogrammable communication systems will require sub-130-nanometer electronics. Legacy single event upset (SEU) radiation-tolerant circuits are ineffective at speeds greater than 125 megahertz. In Phase I of this project, ICs, LLC, demonstrated new base-level logic circuits that provide SEU immunity for sub-130-nanometer high-speed circuits. In Phase II, the company developed an innovative self-restoring logic (SRL) circuit and a system approach that provides high-speed, SEU-tolerant solutions that are effective for sub-130-nanometer electronics scalable to at least 22-nanometer processes. The SRL system can be used in the design of NASA's next-generation special-purpose processors, especially reconfigurable communication processors.

  2. High Temperature Wireless Communication And Electronics For Harsh Environment Applications

    NASA Technical Reports Server (NTRS)

    Hunter, G. W.; Neudeck, P. G.; Beheim, G. M.; Ponchak, G. E.; Chen, L.-Y

    2007-01-01

    In order for future aerospace propulsion systems to meet the increasing requirements for decreased maintenance, improved capability, and increased safety, the inclusion of intelligence into the propulsion system design and operation becomes necessary. These propulsion systems will have to incorporate technology that will monitor propulsion component conditions, analyze the incoming data, and modify operating parameters to optimize propulsion system operations. This implies the development of sensors, actuators, and electronics, with associated packaging, that will be able to operate under the harsh environments present in an engine. However, given the harsh environments inherent in propulsion systems, the development of engine-compatible electronics and sensors is not straightforward. The ability of a sensor system to operate in a given environment often depends as much on the technologies supporting the sensor element as the element itself. If the supporting technology cannot handle the application, then no matter how good the sensor is itself, the sensor system will fail. An example is high temperature environments where supporting technologies are often not capable of operation in engine conditions. Further, for every sensor going into an engine environment, i.e., for every new piece of hardware that improves the in-situ intelligence of the components, communication wires almost always must follow. The communication wires may be within or between parts, or from the engine to the controller. As more hardware is added, more wires, weight, complexity, and potential for unreliability is also introduced. Thus, wireless communication combined with in-situ processing of data would significantly improve the ability to include sensors into high temperature systems and thus lead toward more intelligent engine systems. NASA Glenn Research Center (GRC) is presently leading the development of electronics, communication systems, and sensors capable of prolonged stable

  3. Electronic Learning: Perspectives on Maintaining an Educational Relationship through Electronic Communication.

    ERIC Educational Resources Information Center

    Keenan, Thomas P.

    Fifty gifted teenagers from across Canada, who were taught the Honeywell MULTICS "mail" and "forum" systems, were allowed free reign on an electronic communication system for several months. This paper reports on the students' use of the system, and on some of the interesting and unusual events which occurred during the course of the experiment.…

  4. Pressure dependence on the kinetics of photoinduced intramolecular charge separation in 9,9 prime -bianthryl monitored by picosecond transient absorption: Comparison with electron transfer in photosynthesis

    SciTech Connect

    Lueck, H.; Windsor, M.W. ); Rettig, W. )

    1990-05-31

    Transient absorption spectra of 9,9{prime}-bianthryl (BA) in the picosecond time range have been recorded in nonpolar cyclohexane (CH), in polar acetonitrile (ACN), and in the highly viscous solvent glycerol triacetate (GTA). High pressure (0.1-300 MPa) is employed to vary the solvent properties of GTA over an unusually wide range. To our knowledge, this is the first time that picosecond absorption spectra at high pressures have been reported. Transient spectra (25-ps resolution) in GTA can be resolved into an anthracene-like band corresponding to the locally excited state (LE) and a longer wavelength band corresponding to the twisted intramolecular charge transfer state (TICT). Comparisons are made between ET in BA/GTA and ET in the photosynthetic bacterial reaction center. They suggest that the microscopic structure of the protein in which the chromophores are embedded not only induces the asymmetric charge separation but also provides a polar solvent environment optimized for fast activationless ET and preformed to stabilize the charge-separated chromophores.

  5. Intramolecular Aminoboration of Unfunctionalized Olefins.

    PubMed

    Yang, Chun-Hua; Zhang, Yu-Shi; Fan, Wen-Wen; Liu, Gong-Qing; Li, Yue-Ming

    2015-10-19

    A direct and catalyst-free method for the intramolecular aminoboration of unfunctionalized olefins is reported. In the presence of BCl3 (1 equiv) as the sole boron source, intramolecular aminoboration of sulfonamide derivatives of 4-penten-1-amines, 5-hexen-1-amines, and 2-allylanilines proceeded readily without the use of any catalyst. The boronic acids obtained after hydrolysis could be converted into the corresponding pinacol borates in a straightforward manner by treatment with pinacol under anhydrous conditions. PMID:26331979

  6. Electronic communication improves access, but barriers to its widespread adoption remain.

    PubMed

    Bishop, Tara F; Press, Matthew J; Mendelsohn, Jayme L; Casalino, Lawrence P

    2013-08-01

    Because electronic communication is quick, convenient, and inexpensive for most patients, care that is truly patient centered should promote the use of such communication between patients and providers, even using it as a substitute for office visits when clinically appropriate. Despite the potential benefits of electronic communication, fewer than 7 percent of providers used it in 2008. To learn from the experiences of providers that have widely incorporated electronic communication into patient care, we interviewed leaders of twenty-one medical groups that use it extensively with patients. We also interviewed staff in six of those groups. Electronic communication was widely perceived to be a safe, effective, and efficient means of communication that improves patient satisfaction and saves patients time but that increases the volume of physician work unless office visits are reduced. Practice redesign and new payment methods are likely necessary for electronic communication to be more widely used in patient care. PMID:23918479

  7. 12 CFR 617.7005 - When may electronic communications be used in the borrower rights process?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... borrower rights process? Qualified lenders may use, with the parties' agreement, electronic commerce (E-commerce), including electronic communications for borrower rights disclosures. Part 609 of this chapter... 12 Banks and Banking 7 2012-01-01 2012-01-01 false When may electronic communications be used...

  8. Cooperative Electronic Mail: Effective Communication Technology for Introductory Chemistry

    NASA Astrophysics Data System (ADS)

    Pence, Laura E.

    1999-05-01

    One drawback to using cooperative learning in the classroom is that it takes up class time and reduces the amount of content that can be covered during a semester. Cooperative electronic mail is an excellent alternate method of using cooperative learning that shifts the medium of interaction to the computer and encourages students to learn to communicate effectively through technology. In this project, three types of exercises were assigned, one prior to each exam. These three assignments were (i) an open-ended question, (ii) a traditional cooperative activity done electronically, and (iii) an exercise to allow students to write exam questions for each other. The average participation rate in the exercises was 90% over four semesters, which indicated that the project was an effective incentive to get students to use email regularly. The evaluations of the project were also extremely positive. One surprising result of the assessment was that female students gave even more favorable responses than men, suggesting that this project was an excellent way to encourage women to use computer technology.

  9. Femtosecond laser studies of ultrafast intramolecular processes

    SciTech Connect

    Hayden, C.

    1993-12-01

    The goal of this research is to better understand the detailed mechanisms of chemical reactions by observing, directly in time, the dynamics of fundamental chemical processes. In this work femtosecond laser pulses are used to initiate chemical processes and follow the progress of these processes in time. The authors are currently studying ultrafast internal conversion and subsequent intramolecular relaxation in unsaturated hydrocarbons. In addition, the authors are developing nonlinear optical techniques to prepare and monitor the time evolution of specific vibrational motions in ground electronic state molecules.

  10. A Theory of Electronic Propinquity: Mediated Communication in Organizations.

    ERIC Educational Resources Information Center

    Korzenny, Felipe

    This paper proposes a theoretical approach to mediated communication in organizations. It is argued that the man/machine interface in mediated human communication is better dealt with when a comprehensive theoretical approach is used than when separate communication devices are tested as they appear in the market, such as video-teleconferencing.…

  11. Correlated ab initio investigations on the intermolecular and intramolecular potential energy surfaces in the ground electronic state of the O2-(X2Πg)-HF(X1Σ+) complex

    NASA Astrophysics Data System (ADS)

    Fawzy, Wafaa M.; Elsayed, Mahmoud; Zhang, Yuchen

    2013-01-01

    This work reports the first highly correlated ab initio study of the intermolecular and intramolecular potential energy surfaces in the ground electronic state of the O_2^ - (X{}^2Π _g) - HF(X{}^1Σ^+) complex. Accurate electronic structure calculations were performed using the coupled cluster method including single and double excitations with addition of the perturbative triples correction [CCSD(T)] with the Dunning's correlation consistent basis sets aug-cc-pVnZ, n = 2-5. Also, the explicitly correlated CCSD(T)-F12a level of theory was employed with the AVnZ basis as well as the Peterson and co-workers VnZ-F12 basis sets with n = 2 and 3. Results of all levels of calculations predicted two equivalent minimum energy structures of planar geometry and Cs symmetry along the A″ surface of the complex, whereas the A' surface is repulsive. Values of the geometrical parameters and the counterpoise corrected dissociation energies (Cp-De) that were calculated using the CCSD(T)-F12a/VnZ-F12 level of theory are in excellent agreement with those obtained from the CCSD(T)/aug-cc-pV5Z calculations. The minimum energy structure is characterized by a very short hydrogen bond of length of 1.328 Å, with elongation of the HF bond distance in the complex by 0.133 Å, and De value of 32.313 Kcal/mol. Mulliken atomic charges showed that 65% of the negative charge is localized on the hydrogen bonded end of the superoxide radical and the HF unit becomes considerably polarized in the complex. These results suggest that the hydrogen bond is an incipient ionic bond. Exploration of the potential energy surface confirmed the identified minimum and provided support for vibrationally induced intramolecular proton transfer within the complex. The T-shaped geometry that possesses C2v symmetry presents a saddle point on the top of the barrier to the in-plane bending of the hydrogen above and below the axis that connects centers of masses of the monomers. The height of this barrier is 7

  12. 12 CFR 12.102 - National bank use of electronic communications as customer notifications.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... as customer notifications. 12.102 Section 12.102 Banks and Banking COMPTROLLER OF THE CURRENCY... Interpretations § 12.102 National bank use of electronic communications as customer notifications. (a) In... 12.5 through electronic communications. Where a customer has a facsimile machine, a national bank...

  13. eCAF: A New Tool for the Conversational Analysis of Electronic Communication

    ERIC Educational Resources Information Center

    Duncan-Howell, Jennifer

    2009-01-01

    Electronic communication is characteristically concerned with "the message" (eM), those who send them (S), and those who receive and read them (R). This relationship could be simplified into the equation eM = S + R. When this simple equation is applied to electronic communication, several elements are added that make this straightforward act of…

  14. 78 FR 34132 - Certain Portable Electronic Communications Devices, Including Mobile Phones and Components...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-06

    ... COMMISSION Certain Portable Electronic Communications Devices, Including Mobile Phones and Components Thereof... published a notice (78 FR 12892, May 31, 2013) of receipt of complaint entitled Certain Portable Electronic Communications Devices, Including Mobile Phones and Components Thereof, DN 2958; the Commission...

  15. Using electronic communication safely in health care settings.

    PubMed

    Broussard, Brenda S; Broussard, Anne B

    2013-01-01

    Nurses are increasingly using mobile and other devices, such as cell phones, smartphones, tablets, bar-coding scanners, monitoring equipment and bedside computers, to communicate with members of the health care team and with patients. Communication accomplished with such devices includes direct verbal communication, text-messaging, emailing, obtaining patient care information and accessing medical records for order entry and for documenting nursing care. Problems that could occur with such communication methods include distraction, errors, de-personalized care, violation of confidentiality and transmission of nosocomial pathogens. Policies are needed to prevent inappropriate use of technological devices in patient care and to promote patient safety and quality care with their use. PMID:23399014

  16. Direct measurements of intramolecular electron transfer rates between cytochrome c and cytochrome c peroxidase: effects of exothermicity and primary sequence on rate

    SciTech Connect

    Cheung, E.; Taylor, K.; Kornblatt, J.A.; English, A.M.; McLendon, G.; Miller, J.R.

    1986-03-01

    Rapid mixing of ferrocytochrome c peroxidase (cyt c peroxidase(II)) and ferricytochrome c (cyt c(III)) results in the reduction of cyt c(III) by cyt c peroxidase(II). In 10 mM phosphate, pH 7.0, the rate of decay of cyt c peroxidase(II) and the rate of accumulation of cyt c(II) give equal first-order rate constants. Equivalent results are obtained by pulse radiolysis using isopropanol radical as the reducing agent. This rate is independent of the initial cyt c(III):cyt c peroxidase(II) ratios. These results are consistent with unimolecular electron transfer occurring within a cyt c(III)-cyt c peroxidase(II) complex. When cyt c is replaced by porphyrin cyt c (iron-free cyt c), a complex still forms with cyt c peroxidase. On radiolysis intracomplex electron transfer occurs from the porphyrin cyt c anion radical to cyt c peroxidase(III). This large rate increase suggest that the barrier for intracomplex electron transfer is large. Finally, the authors have briefly investigated how the cyt c peroxidase(II) ..-->.. cyt c(III) rate depends on the primary structure of cyt c(III). They find the reactivity order to be as follows: yeast > horse > tuna.

  17. Scholarship and Scholarly Communication in the Electronic Age.

    ERIC Educational Resources Information Center

    Chodorow, Stanley

    2000-01-01

    Discusses scholarly communication and economic factors that are affecting it. Highlights include a history of the scholarly community beginning with Francis Bacon; price increases that affected library budgets; relationships between faculty and universities; expansion of higher education; and use of the World Wide Web for scholarly communication.…

  18. Perceptions of Undergraduate Students and Faculty Regarding the Impact of Electronic Communication on the Written-Communication Skills of Undergraduate Students

    ERIC Educational Resources Information Center

    Houser, Laura Ann Camlet

    2012-01-01

    This narrative-qualitative study investigated the perceived impact that electronic communication has on the written-communication skills of undergraduate students. Open-ended survey questions queried the experiences of undergraduate students who use electronic communication, as well as the perceptions of faculty who teach undergraduate students.…

  19. Performance Analysis and Electronics Packaging of the Optical Communications Demonstrator

    NASA Technical Reports Server (NTRS)

    Jeganathan, M.; Monacos, S.

    1998-01-01

    The Optical Communications Demonstrator (OCD), under development at the Jet Propulsion Laboratory (JPL), is a laboratory-based lasercomm terminal designed to validate several key technologies, primarily precision beam pointing, high bandwidth tracking, and beacon acquisition.

  20. Intramolecular electron density redistribution upon hydrogen bond formation in the anion methyl orange at the water/1,2-dichloroethane interface probed by phase interference second harmonic generation

    PubMed

    Rinuy; Piron; Brevet; Blanchard-Desce; Girault

    2000-09-15

    Surface second harmonic generation (SSHG) studies of the azobenzene derivative p-dimethylaminoazobenzene sulfonate, often referred as Methyl Orange (MO), at the neat water/1,2-dichloroethane (DCE) interface is reported. The two forms of the anionic MO dye, which are usually observed in bulk solution, with one form being hydrogen bonded to a water molecule through the azo nitrogens (MO/H2O) and the other form not being hydrogen bonded (MO) have also been observed at the water/DCE interface. Their equilibrium constant has been compared with the corresponding bulk solution and found to be identical. The adsorption equilibrium of the two forms has been determined and the Gibbs energy of adsorption measured to be -30 kJmol(-1) for both forms. From a light polarisation analysis of the SH signal, the angle of orientation of the MO transition dipole moment was found to be 34 +/- 2 degrees for MO and 43 +/- 2 degrees for MO/H2O under the assumption of a Dirac delta function for the angle distribution, a difference explained by the different solvation properties of the two forms. Furthermore, the wavelength dependence analysis of these data revealed an interference pattern resulting from the electronic density redistribution within the hydrated anionic form occurring upon the formation of the hydrogen bond with a water molecule. This interference pattern was clearly evidenced with the use of another dye at the interface in order to define a phase reference to both forms of Methyl Orange. PMID:11039537

  1. Security infrastructure requirements for electronic health cards communication.

    PubMed

    Pharow, Peter; Blobel, Bernd

    2005-01-01

    Communication and co-operation processes in the healthcare and welfare domain require a security infrastructure based on services describing status and relation of communicating principals as well as corresponding keys and attributes. Additional services provide trustworthy information on dynamic issues of communication and co-operation such as time and location of processes, workflow relations, integrity of archives and record systems, and system behaviour. To provide this communication and co-operation in a shared care environment, smart cards are widely used. Serving as storage media and portable application systems, patient data cards enable patient-controlled exchange and use of personal health data bound to specific purposes such as prescription and disease management. Additionally, patient status data such as the emergency data set or immunization may be stored in, and communicated by, patient data cards. Another deployment field of smart cards is their token functionality within a security framework, supporting basic security services such as identification, authentication, integrity, confidentiality, or accountability using cryptographic algorithms. In that context, keys, certificates, and card holder's attributes might be stored in the card as well. As an example, the German activity of introducing patient health cards and health professional cards is presented. Specification and enrolment aspects are on-going processes. PMID:16160291

  2. Dual Site-Controlled and Lysosome-Targeted Intramolecular Charge Transfer-Photoinduced Electron Transfer-Fluorescence Resonance Energy Transfer Fluorescent Probe for Monitoring pH Changes in Living Cells.

    PubMed

    Dong, Baoli; Song, Xuezhen; Wang, Chao; Kong, Xiuqi; Tang, Yonghe; Lin, Weiying

    2016-04-01

    Acidic pH is a critical physiological factor for controlling the activities and functions of lysosome. Herein, we report a novel dual site-controlled and lysosome-targeted intramolecular charge transfer-photoinduced electron transfer-Fluorescence resonance energy transfer (ICT-PET-FRET) fluorescent probe (CN-pH), which was essentially the combination of a turn-on pH probe (CN-1) and a turn-off pH probe (CN-2) by a nonconjugated linker. Coumarin and naphthalimide fluorophores were selected as donor and acceptor to construct the FRET platform. Hydroxyl group and morpholine were simultaneously employed as the two pH sensing sites and controlled the fluorescence of coumarin and naphthalimide units by ICT and PET, respectively. The sensing mechanism of CN-pH to pH was essentially an integration of ICT, PET, and FRET processes. Meanwhile, the morpholine also can serve as a lysosome-targeted group. By combining the two data analysis approaches of the ratios of the two emission intensities (R) and the reverse ratio R' (R' = 1/R), the fluorescent ratio of CN-pH can show proportional relationship to pH values in a very broad range from pH 4.0 to 8.0 with high sensitivity. The probe has been successfully applied for the fluorescence imaging of the lysosomal pH values, as well as ratiometrically visualizing chloroquine-stimulated changes of intracellular pH in living cells. These features demonstrate that the probe can afford practical application in biological systems. PMID:26987045

  3. The Herald: An Electronic Aid to Communication for Severely Physically Handicapped.

    ERIC Educational Resources Information Center

    Wilkins, Robert L.; Means, Diane W.

    Examined are ways in which adaptive aids make communication available to nonverbal severely physically handicapped persons. Techniques for initial assessment are described, including evaluation of outward orientation, motor control and binary choice system. The Herald, an electronic communication board, is said to meet criteria of adaptability,…

  4. Complexes with Tunable Intramolecular Ferrocene to Ti(IV) Electronic Transitions: Models for Solid State Fe(II) to Ti(IV) Charge Transfer.

    PubMed

    Turlington, Michael D; Pienkos, Jared A; Carlton, Elizabeth S; Wroblewski, Karlee N; Myers, Alexis R; Trindle, Carl O; Altun, Zikri; Rack, Jeffrey J; Wagenknecht, Paul S

    2016-03-01

    Iron(II)-to-titanium(IV) metal-to-metal-charge transfer (MMCT) is important in the photosensitization of TiO2 by ferrocyanide, charge transfer in solid-state metal-oxide photocatalysts, and has been invoked to explain the blue color of sapphire, blue kyanite, and some lunar material. Herein, a series of complexes with alkynyl linkages between ferrocene (Fc) and Ti(IV) has been prepared and characterized by UV-vis spectroscopy and electrochemistry. Complexes with two ferrocene substituents include Cp2Ti(C2Fc)2, Cp*2Ti(C2Fc)2, and Cp2Ti(C4Fc)2. Complexes with a single ferrocene utilize a titanocene with a trimethylsilyl derivatized Cp ring, (TMS)Cp, and comprise the complexes (TMS)Cp2Ti(C2Fc)(C2R), where R = C6H5, p-C6H4CF3, and CF3. The complexes are compared to Cp2Ti(C2Ph)2, which lacks the second metal. Cyclic voltammetry for all complexes reveals a reversible Ti(IV/III) reduction wave and an Fe(II/III) oxidation that is irreversible for all complexes except (TMS)Cp2Ti(C2Fc)(C2CF3). All of the complexes with both Fc and Ti show an intense absorption (4000 M(-1)cm(-1) < ε < 8000 M(-1)cm(-1)) between 540 and 630 nm that is absent in complexes lacking a ferrocene donor. The energy of the absorption tracks with the difference between the Ti(IV/III) and Fe(III/II) reduction potentials, shifting to lower energy as the difference in potentials decreases. Reorganization energies, λ, have been determined using band shape analysis (2600 cm(-1) < λ < 5300 cm(-1)) and are in the range observed for other donor-acceptor complexes that have a ferrocene donor. Marcus-Hush-type analysis of the electrochemical and spectroscopic data are consistent with the assignment of the low-energy absorption as a MMCT band. TD-DFT analysis also supports this assignment. Solvatochromism is apparent for the MMCT band of all complexes, there being a bathochromic shift upon increasing polarizability of the solvent. The magnitude of the shift is dependent on both the electron density at Ti

  5. Use and Acceptance of Electronic Communication by Patients With Multiple Sclerosis: A Multicenter Questionnaire Study

    PubMed Central

    Schultheiss, Thorsten; Kempcke, Raimar; Thomas, Katja; Ziemssen, Tjalf

    2012-01-01

    Background The number of multiple sclerosis (MS) information websites, online communities, and Web-based health education programs has been increasing. However, MS patients’ willingness to use new ways of communication, such as websites, mobile phone application, short message service, or email with their physician, remains unknown. Objectives We designed a questionnaire to evaluate the a priori use of electronic communication methods by MS patients and to assess their acceptance of such tools for communication with their health care providers. Methods We received complete data from 586 MS patients aged between 17 and 73 years. Respondents were surveyed in outpatient clinics across Germany using a novel paper-and-pencil questionnaire. In addition to demographics, the survey items queried frequency of use of, familiarity with, and comfort with using computers, websites, email, and mobile phones. Results About 90% of all MS patients used a personal computer (534/586) and the Internet (527/586) at least once a week, 87.0% (510/586) communicated by email, and 85.6% (488/570) communicated by mobile phone. When asked about their comfort with using electronic communication methods for communication with health care providers, 20.5% (120/586) accepted communication by mobile Internet application or short message service via mobile phone, 41.0% (240/586) by websites, 54.3% (318/586) by email service, and 67.8% (397/586) by at least one type of electronic communication. The level of a priori use was the best predictor for the acceptance of electronic communication with health care providers. Patients who reported already searching online for health information (odds ratio 2.4, P < .001) and who had already communicated with a physician through a website (odds ratio 3.3, P = .03) reported higher acceptance for Web-based communication. Patients who already scheduled appointments with their mobile phones (odds ratio 2.1, P = .002) were more likely to accept the use of mobile

  6. Communication.

    ERIC Educational Resources Information Center

    Strauss, Andre

    The following essays on communication are presented: communication as a condition of survival, communication for special purposes, the means of transmission of communication, communication within social and economic structures, the teaching of communication through the press, the teaching of modern languages, communication as a point of departure,…

  7. Quantitative Intramolecular Singlet Fission in Bipentacenes.

    PubMed

    Sanders, Samuel N; Kumarasamy, Elango; Pun, Andrew B; Trinh, M Tuan; Choi, Bonnie; Xia, Jianlong; Taffet, Elliot J; Low, Jonathan Z; Miller, John R; Roy, Xavier; Zhu, X-Y; Steigerwald, Michael L; Sfeir, Matthew Y; Campos, Luis M

    2015-07-22

    Singlet fission (SF) has the potential to significantly enhance the photocurrent in single-junction solar cells and thus raise the power conversion efficiency from the Shockley-Queisser limit of 33% to 44%. Until now, quantitative SF yield at room temperature has been observed only in crystalline solids or aggregates of oligoacenes. Here, we employ transient absorption spectroscopy, ultrafast photoluminescence spectroscopy, and triplet photosensitization to demonstrate intramolecular singlet fission (iSF) with triplet yields approaching 200% per absorbed photon in a series of bipentacenes. Crucially, in dilute solution of these systems, SF does not depend on intermolecular interactions. Instead, SF is an intrinsic property of the molecules, with both the fission rate and resulting triplet lifetime determined by the degree of electronic coupling between covalently linked pentacene molecules. We found that the triplet pair lifetime can be as short as 0.5 ns but can be extended up to 270 ns. PMID:26102432

  8. Ab initio of the intramolecular dynamics trifluoronitromethane

    SciTech Connect

    Roehrig, M.A.; McCarthy, W.J.; Kukolich, S.G.; Adamowicz, L.

    1993-12-31

    Several experimental studies of trifluoronitromethane have indicated that this molecule undergoes a low energy motion corresponding to an internal rotation of the CF{sub 3} relative to the NO{sub 2} group. Values for the V{sub 6} barrier have been obtained by electron diffraction and microwave spectroscopy to be 3 kcal/mol and 74 cal/mol respectively. A theoretical study of this molecule investigating this and possible other low energy motions is currently underway. Results from this study should reveal new information on the low barrier dynamics and shed some light on this large discrepancy on the V{sub 6} barriers. Preliminary calculations seem to indicate that a simple V{sub 6} barrier does not adequately describe the intramolecular dynamics of this molecule.

  9. Electronic Pathways. Adult Learning and the New Communication Technologies.

    ERIC Educational Resources Information Center

    Field, Jane, Ed.

    This book, which is intended as a practical resource for individuals who are professionally concerned with adult learning, contains 21 papers and 3 checklists concerning the new communication and information technologies (IT) and adult learning. The following papers and checklists are included: "Introduction" (Jane Field); "The Use of Telematics…

  10. Electronic Play, Study, Communication, and Adolescent Achievement, 2003-2008

    ERIC Educational Resources Information Center

    Hofferth, Sandra L.; Moon, Ui Jeong

    2012-01-01

    Adolescents' time spent messaging, exploring websites, and studying on the computer increased between 2003 and 2008. Using data from the Panel Study of Income Dynamics Child Development Supplement, this study examines how such changes have influenced individual achievement and behavior from childhood to adolescence. Greater communications and…

  11. Communication: Time- and space-sliced velocity map electron imaging

    SciTech Connect

    Lee, Suk Kyoung; Lin, Yun Fei; Lingenfelter, Steven; Fan, Lin; Winney, Alexander H.; Li, Wen

    2014-12-14

    We develop a new method to achieve slice electron imaging using a conventional velocity map imaging apparatus with two additional components: a fast frame complementary metal-oxide semiconductor camera and a high-speed digitizer. The setup was previously shown to be capable of 3D detection and coincidence measurements of ions. Here, we show that when this method is applied to electron imaging, a time slice of 32 ps and a spatial slice of less than 1 mm thick can be achieved. Each slice directly extracts 3D velocity distributions of electrons and provides electron velocity distributions that are impossible or difficult to obtain with a standard 2D imaging electron detector.

  12. High temperature superconductor analog electronics for millimeter-wavelength communications

    NASA Technical Reports Server (NTRS)

    Romanofsky, R. R.; Bhasin, K. B.

    1991-01-01

    The performance of high temperature superconductor (HTS) passive microwave circuits up to X-band was encouraging when compared to their metallic counterparts. The extremely low surface resistance of HTS films up to about 10 GHz enables a reduction in loss by as much as 100 times compared to copper when both materials are kept at about 77 K. However, a superconductor's surface resistance varies in proportion to the frequency squared. Consequently, the potential benefit of HTS materials to millimeter-wave communications requires careful analysis. A simple ring resonator was used to evaluate microstrip losses at Ka-band. Additional promising components were investigated such as antennas and phase shifters. Prospects for HTS to favorable impact millimeter-wave communications systems are discussed.

  13. High reliability K-band electron tubes for satellite communication

    NASA Astrophysics Data System (ADS)

    Hirata, H.; Kawashima, F.

    1980-09-01

    Design methods and performance results for long life and high reliability satellite TWT and high power klystron with wide band tunability are presented. Emphasis is placed on problems observed during early operation. Tuning instability is solved by analyzing possible spurious modes at the tuner and by designing a structure to suppress spurious modes. A feedback mechanism is also discussed to handle instability in preset-tuning. Cathode design, electron beam focusing, and electron gun structure at a high frequency band are examined.

  14. Communication and Industrial Electronics. Trade and Industrial Education Trade Preparatory Training Guide.

    ERIC Educational Resources Information Center

    Nebraska State Dept. of Education, Lincoln. Div. of Vocational Education.

    One of a series of curriculum guides prepared for the electricity/electronics occupations cluster, this guide identifies the essentials of the communication and industrial electronics trade as recommended by the successful electrical servicemen. An instructional program based upon the implementation of the guide is expected to prepare a student to…

  15. 12 CFR 617.7005 - When may electronic communications be used in the borrower rights process?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... borrower rights process? Qualified lenders may use, with the parties' agreement, electronic commerce (E-commerce), including electronic communications for borrower rights disclosures. Part 609 of this chapter addresses when a qualified lender may use E-commerce. Consistent with these rules, a qualified lender...

  16. 12 CFR 617.7005 - When may electronic communications be used in the borrower rights process?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... borrower rights process? Qualified lenders may use, with the parties' agreement, electronic commerce (E-commerce), including electronic communications for borrower rights disclosures. Part 609 of this chapter addresses when a qualified lender may use E-commerce. Consistent with these rules, a qualified lender...

  17. Electronic Communication in Africa--the Promotion of Animal Health Information Dissemination.

    ERIC Educational Resources Information Center

    van der Westhuizen, Erica E.; Miller, E. Stan

    1995-01-01

    Discusses how the Veterinary Science Library at the University of Pretoria (South Africa) promotes electronic communication through various Internet and other network links. Provides a sample of online information sources available to veterinary teams and animal health workers, and a list of electronic addresses for South African libraries and…

  18. 12 CFR 617.7005 - When may electronic communications be used in the borrower rights process?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... borrower rights process? Qualified lenders may use, with the parties' agreement, electronic commerce (E-commerce), including electronic communications for borrower rights disclosures. Part 609 of this chapter addresses when a qualified lender may use E-commerce. Consistent with these rules, a qualified lender...

  19. The Design and Development of Electronic Documents for International Business Communication.

    ERIC Educational Resources Information Center

    Sondak, Eileen M.; Sondak, Norman E.

    This paper identifies three basic criteria for good business communications on an international level--clarity, effectiveness, and good will--and presents a model for effective information transfer via electronic media. It argues that electronic mail (e-mail) messages do not meet these criteria even though more and more domestic and international…

  20. 12 CFR 617.7005 - When may electronic communications be used in the borrower rights process?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... borrower rights process? Qualified lenders may use, with the parties' agreement, electronic commerce (E-commerce), including electronic communications for borrower rights disclosures. Part 609 of this chapter addresses when a qualified lender may use E-commerce. Consistent with these rules, a qualified lender...

  1. Mass Communication and Journalism Faculty and Their Electronic Communication with College Students: A Nationwide Examination

    ERIC Educational Resources Information Center

    Brunner, Brigitta R.; Yates, Bradford L.; Adams, Jennifer Wood

    2008-01-01

    Nearly 700 U.S. journalism and mass communication faculty reported their perceptions of student e-mail use via a Web-based survey. This nationwide study focused on content of e-mail received by faculty and made comparisons based on faculty gender. Nearly half of the respondents reported that they occasionally receive e-mails from students before a…

  2. Low Power/Low Noise Electronics Technologies for Wireless Communications

    NASA Astrophysics Data System (ADS)

    Itoh, Tatsuo

    2002-01-01

    We had previously written a Final Report for this award on August 1, 2001. At that time we provided ARO, as Appendix to Final Report, with three copies of the book 'RF Technologies for Low Power Wireless Communications'. Due to administrative reasons, we requested and were granted an extended contractual period to January 31, 2002. This period was used only to complete the last remaining technical activity that was carried out by the group of T. Itoh in the area of Active Integrated Antennas based on GaN transistor.

  3. Communication: Electron diffraction of ferrocene in superfluid helium droplets

    PubMed Central

    2016-01-01

    We report electron diffraction of ferrocene doped in superfluid helium droplets. By taking advantage of the velocity slip in our pulsed droplet beam using a pulsed electron gun, and by doping with a high concentration of ferrocene delivered via a pulsed valve, we can obtain high quality diffraction images from singly doped droplets. Under the optimal doping conditions, 80% of the droplets sampled in the electron beam are doped with just one ferrocene molecule. Extension of this size selection method to dopant clusters has also been demonstrated. However, incomplete separation of dopant clusters might require deconvolution and modeling of the doping process. This method can be used for studies of nucleation processes in superfluid helium droplets. PMID:27305988

  4. Communication: Electron diffraction of ferrocene in superfluid helium droplets.

    PubMed

    Zhang, Jie; He, Yunteng; Kong, Wei

    2016-06-14

    We report electron diffraction of ferrocene doped in superfluid helium droplets. By taking advantage of the velocity slip in our pulsed droplet beam using a pulsed electron gun, and by doping with a high concentration of ferrocene delivered via a pulsed valve, we can obtain high quality diffraction images from singly doped droplets. Under the optimal doping conditions, 80% of the droplets sampled in the electron beam are doped with just one ferrocene molecule. Extension of this size selection method to dopant clusters has also been demonstrated. However, incomplete separation of dopant clusters might require deconvolution and modeling of the doping process. This method can be used for studies of nucleation processes in superfluid helium droplets. PMID:27305988

  5. Communication: Electron diffraction of ferrocene in superfluid helium droplets

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; He, Yunteng; Kong, Wei

    2016-06-01

    We report electron diffraction of ferrocene doped in superfluid helium droplets. By taking advantage of the velocity slip in our pulsed droplet beam using a pulsed electron gun, and by doping with a high concentration of ferrocene delivered via a pulsed valve, we can obtain high quality diffraction images from singly doped droplets. Under the optimal doping conditions, 80% of the droplets sampled in the electron beam are doped with just one ferrocene molecule. Extension of this size selection method to dopant clusters has also been demonstrated. However, incomplete separation of dopant clusters might require deconvolution and modeling of the doping process. This method can be used for studies of nucleation processes in superfluid helium droplets.

  6. Quaternary pulse position modulation electronics for free-space laser communications

    NASA Technical Reports Server (NTRS)

    Budinger, J. M.; Kerslake, S. D.; Nagy, L. A.; Shalkhauser, M. J.; Soni, N. J.; Cauley, M. A.; Mohamed, J. H.; Stover, J. B.; Romanofsky, R. R.; Lizanich, P. J.

    1991-01-01

    The development of a high data-rate communications electronic subsystem for future application in free-space, direct-detection laser communications is described. The dual channel subsystem uses quaternary pulse position modulation (QPPM) and operates at a throughput of 650 megabits per second. Transmitting functions described include source data multiplexing, channel data multiplexing, and QPPM symbol encoding. Implementation of a prototype version in discrete gallium arsenide logic, radiofrequency components, and microstrip circuitry is presented.

  7. Quaternary pulse position modulation electronics for free-space laser communications

    NASA Technical Reports Server (NTRS)

    Budinger, J. M.; Kerslake, S. D.; Nagy, L. A.; Shalkhauser, M. J.; Soni, N. J.; Cauley, M. A.; Mohamed, J. H.; Stover, J. B.; Romanofsky, R. R.; Lizanich, P. J.

    1991-01-01

    The development of a high data-rate communications electronic subsystem for future application in free-space, direct-detection laser communications is described. The dual channel subsystem uses quaternary pulse position modulation (GPPM) and operates at a throughput of 650 megabits per second. Transmitting functions described include source data multiplexing, channel data multiplexing, and QPPM symbol encoding. Implementation of a prototype version in discrete gallium arsenide logic, radiofrequency components, and microstrip circuitry is presented.

  8. Debunking the Myth of the Nintendo Generation: How Doctoral Students Introduce New Electronic Communication Practices into University Research.

    ERIC Educational Resources Information Center

    Covi, Lisa M.

    2000-01-01

    Provides empirical evidence of how doctoral students and their faculty advisors use electronic communication technologies. Examines work patterns of doctoral students and data on recent introduction of new electronic communication practices, offering an alternative explanation to the Nintendo Generation Myth that claims electronic communication…

  9. Direction of CRT waste glass processing: Electronics recycling industry communication

    SciTech Connect

    Mueller, Julia R.; Boehm, Michael W.; Drummond, Charles

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Given a large flow rate of CRT glass {approx}10% of the panel glass stream will be leaded. Black-Right-Pointing-Pointer The supply of CRT waste glass exceeded demand in 2009. Black-Right-Pointing-Pointer Recyclers should use UV-light to detect lead oxide during the separation process. Black-Right-Pointing-Pointer Recycling market analysis techniques and results are given for CRT glass. Black-Right-Pointing-Pointer Academic initiatives and the necessary expansion of novel product markets are discussed. - Abstract: Cathode Ray Tube, CRT, waste glass recycling has plagued glass manufacturers, electronics recyclers and electronics waste policy makers for decades because the total supply of waste glass exceeds demand, and the formulations of CRT glass are ill suited for most reuse options. The solutions are to separate the undesirable components (e.g. lead oxide) in the waste and create demand for new products. Achieving this is no simple feat, however, as there are many obstacles: limited knowledge of waste glass composition; limited automation in the recycling process; transportation of recycled material; and a weak and underdeveloped market. Thus one of the main goals of this paper is to advise electronic glass recyclers on how to best manage a diverse supply of glass waste and successfully market to end users. Further, this paper offers future directions for academic and industry research. To develop the recommendations offered here, a combination of approaches were used: (1) a thorough study of historic trends in CRT glass chemistry; (2) bulk glass collection and analysis of cullet from a large-scale glass recycler; (3) conversations with industry members and a review of potential applications; and (4) evaluation of the economic viability of specific uses for recycled CRT glass. If academia and industry can solve these problems (for example by creating a database of composition organized by manufacturer and glass source

  10. E-Communications 101: Here Is Your Guide to Efficient Communication in an Electronic Age

    ERIC Educational Resources Information Center

    Solomon, Gwen

    2004-01-01

    More tasks than ever are heading online these days--from student projects and field trips to virtual schools and electronic professional development. The big idea is that technology saves time and effort, focuses people quickly and easily, and commands attention in a world of too many demands, distractions, and delivery systems. So what are the…

  11. Patients’ Perspective of the Design of Provider-Patients Electronic Communication Services

    PubMed Central

    Silhavy, Petr; Silhavy, Radek; Prokopova, Zdenka

    2014-01-01

    Information Delivery is one the most important tasks in healthcare practice. This article discusses patient’s tasks and perspectives, which are then used to design a new Effective Electronic Methodology. The system design methods applicable to electronic communication in the healthcare sector are also described. The architecture and the methodology for the healthcare service portal are set out in the proposed system design. PMID:24927038

  12. Hermetic electronic packaging of an implantable brain-machine-interface with transcutaneous optical data communication.

    PubMed

    Schuettler, Martin; Kohler, Fabian; Ordonez, Juan S; Stieglitz, Thomas

    2012-01-01

    Future brain-computer-interfaces (BCIs) for severely impaired patients are implanted to electrically contact the brain tissue. Avoiding percutaneous cables requires amplifier and telemetry electronics to be implanted too. We developed a hermetic package that protects the electronic circuitry of a BCI from body moisture while permitting infrared communication through the package wall made from alumina ceramic. The ceramic package is casted in medical grade silicone adhesive, for which we identified MED2-4013 as a promising candidate. PMID:23366777

  13. Advancing Partner Notification Through Electronic Communication Technology: A Review of Acceptability and Utilization Research.

    PubMed

    Pellowski, Jennifer; Mathews, Catherine; Kalichman, Moira O; Dewing, Sarah; Lurie, Mark N; Kalichman, Seth C

    2016-06-01

    A cornerstone of sexually transmitted infection (STI) prevention is the identification, tracing, and notification of sex partners of index patients. Although partner notification reduces disease burden and prevents new infections as well as reinfections, studies show that only a limited number of partners are ever notified. Electronic communication technologies, namely, the Internet, text messaging, and phone calls (i.e., e-notification), have the potential to expand partner services. We conducted a systematic review of studies that have investigated the acceptability and utility of e-notification. We identified 23 studies that met the following criteria: (a) 9 studies presented data on the acceptability of technology-based communications for contacting sex partner(s), and (b) 14 studies reported on the utilization of communication technologies for partner notification. Studies found high levels of interest in and acceptability of e-notification; however, there was little evidence for actual use of e-notification. Taken together, results suggest that electronic communications could have their greatest impact in notifying less committed partners who would otherwise be uninformed of their STI exposure. In addition, all studies to date have been conducted in resource-rich countries, although the low cost of e-notification may have its greatest impact in resource-constrained settings. Research is needed to determine the best practices for exploiting the opportunities afforded by electronic communications for expanding STI partner services. PMID:27144318

  14. Advancing Partner Notification Through Electronic Communication Technology: A Review of Acceptability and Utilization Research

    PubMed Central

    PELLOWSKI, JENNIFER; MATHEWS, CATHERINE; KALICHMAN, MOIRA O.; DEWING, SARAH; LURIE, MARK N.; KALICHMAN, SETH C.

    2016-01-01

    A cornerstone of sexually transmitted infection (STI) prevention is the identification, tracing, and notification of sex partners of index patients. Although partner notification reduces disease burden and prevents new infections as well as reinfections, studies show that only a limited number of partners are ever notified. Electronic communication technologies, namely, the Internet, text messaging, and phone calls (i.e., e-notification), have the potential to expand partner services. We conducted a systematic review of studies that have investigated the acceptability and utility of e-notification. We identified 23 studies that met the following criteria: (a) 9 studies presented data on the acceptability of technology-based communications for contacting sex partner(s), and (b) 14 studies reported on the utilization of communication technologies for partner notification. Studies found high levels of interest in and acceptability of e-notification; however, there was little evidence for actual use of e-notification. Taken together, results suggest that electronic communications could have their greatest impact in notifying less committed partners who would otherwise be uninformed of their STI exposure. In addition, all studies to date have been conducted in resource-rich countries, although the low cost of e-notification may have its greatest impact in resource-constrained settings. Research is needed to determine the best practices for exploiting the opportunities afforded by electronic communications for expanding STI partner services. PMID:27144318

  15. Improving Efficiency and Reducing Administrative Burden through Electronic Communication

    PubMed Central

    Cook, Katlyn E; Ludens, Gail M; Ghosh, Amit K; Mundell, William C; Fleming, Kevin C; Majka, Andrew J

    2013-01-01

    Background: The InBox messaging system is an internal, electronic program used at Mayo Clinic, Rochester, MN, to facilitate the sending, receiving, and answering of patient-specific messages and alerts. A standardized InBox was implemented in the Division of General Internal Medicine to decrease the time physicians, physician assistants, and nurse practitioners (clinicians) spend on administrative tasks and to increase efficiency. Methods: Clinicians completed surveys and a preintervention InBox pilot test to determine inefficiencies related to administrative burdens and defects (message entry errors). Results were analyzed using Pareto diagrams, value stream mapping, and root cause analysis to prioritize administrative-burden inefficiencies to develop a new, standardized InBox. Clinicians and allied health staff were the target of this intervention and received standardized InBox training followed by a postintervention pilot test for clinicians. Results: Sixteen of 28 individuals (57%) completed the preintervention survey. Twenty-eight clinicians participated in 2 separate 8-day pilot tests (before and after intervention) for the standardized InBox. The number of InBox defects was substantially reduced from 37 (Pilot 1) to 7 (Pilot 2). Frequent InBox defects decreased from 25% to 10%. More than half of clinicians believed the standardized InBox positively affected their work, and 100% of clinicians reported no negative affect on their work. Conclusions: This project demonstrated the successful implementation of the standardized InBox messaging system. Initial assessments show substantial reduction of InBox entry defects and administrative tasks completed by clinicians. The findings of this project suggest increased clinician and allied health staff efficiency, satisfaction, improved clinician work-life balance, and decreased clinician burden caused by administrative tasks. PMID:23596365

  16. Security of electronic mental health communication and record-keeping in the digital age.

    PubMed

    Elhai, Jon D; Frueh, B Christopher

    2016-02-01

    The mental health field has seen a trend in recent years of the increased use of information technology, including mobile phones, tablets, and laptop computers, to facilitate clinical treatment delivery to individual patients and for record keeping. However, little attention has been paid to ensuring that electronic communication with patients is private and secure. This is despite potentially deleterious consequences of a data breach, which are reported in the news media very frequently in modern times. In this article, we present typical security concerns associated with using technology in clinical services or research. We also discuss enhancing the privacy and security of electronic communication with clinical patients and research participants. We offer practical, easy-to-use software application solutions for clinicians and researchers to secure patient communication and records. We discuss such issues as using encrypted wireless networks, secure e-mail, encrypted messaging and videoconferencing, privacy on social networks, and others. PMID:26301860

  17. Electronically Recorded Music as a Communication Medium: A Structural Analysis with Selected Bibliography.

    ERIC Educational Resources Information Center

    Jorgensen, Earl; Mabry, Edward A.

    During the past decade, the influence of electronically recorded music and the message it transmits have caused media scholars to reexamine and modify the theories upon which the basic process of communication is dependent. While the five primary functions (source, transmitter, channel, receiver, and destination) remain unchanged, an additional…

  18. 77 FR 70464 - Certain Electronic Devices, Including Wireless Communication Devices, Portable Music and Data...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-26

    ... Telecommunications America, LLC of Richardson, Texas (collectively, ``Samsung''). 76 FR 45860 (Aug. 1, 2011). The... Presidential Memorandum of July 21, 2005, 70 FR 43251 (July 26, 2005). During this period, the subject articles... COMMISSION Certain Electronic Devices, Including Wireless Communication Devices, Portable Music and...

  19. 78 FR 16865 - Certain Electronic Devices, Including Wireless Communication Devices, Portable Music and Data...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-19

    ... America, LLC of Richardson, Texas (collectively, ``Samsung''). 76 FR 45860 (Aug. 1, 2011). The complaint... Commission, and on the issues of remedy, the public interest, and bonding. 77 FR 70464. The Commission... COMMISSION Certain Electronic Devices, Including Wireless Communication Devices, Portable Music and...

  20. The Relevancy of Graduate Curriculum to Human Resource Professionals' Electronic Communication.

    ERIC Educational Resources Information Center

    Hoell, Robert C.; Henry, Gordon O.

    2003-01-01

    Electronic communications of human resource professionals and the content of 23 university human resource management courses were categorized using the Human Resource Certification Institute's body of knowledge. Differences between proportion of topics discussed and topics covered in curricula suggest some topics are over- or undertaught.…

  1. Encouraging and Supporting Electronic Communication across the Curriculum (ECAC) through a University and K-12 Partnership.

    ERIC Educational Resources Information Center

    DeVoss, Danielle Nicole; Selfe, Dickie

    2002-01-01

    Presents an approach to remedying the technological turbulence that both k-12 and university faculty face. Describes the Electronic Communication Across the Curriculum Summer Workshop. Offers this workshop as a model approach for other workshop developers, for those interested in educational partnerships, and for those committed to professional…

  2. Confronting the Ubiquity of Electronic Communication and Social Media: Ethical and Legal Considerations for Psychoeducational Practice

    ERIC Educational Resources Information Center

    Demers, Joseph A.; Sullivan, Amanda L.

    2016-01-01

    Most U.S. children and adults use computers and the Internet on a daily basis. The pervasiveness of electronic communication in a variety of contexts, including home and school, raises ethical and legal concerns for school psychologists and those in related fields of practice, because of the risks to privacy and confidentiality, boundaries,…

  3. Electronic Communication and Its Influence on Parental Involvement in High School

    ERIC Educational Resources Information Center

    Watkins, Aaron

    2013-01-01

    This study investigated the effect of electronic communication has on parent's involvement with their high school child's education. The No Child Left Behind Act of 2001 (NCLB) specifically requires that schools find ways to increase parental involvement; this requirement stemmed from evidence that involvement tends to decline as the students…

  4. 78 FR 32689 - Certain Portable Electronic Communications Devices, Including Mobile Phones and Components...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-31

    ...Notice is hereby given that the U.S. International Trade Commission has received a complaint entitled Certain Portable Electronic Communications Devices, Including Mobile Phones and Components Thereof, DN 2958; the Commission is soliciting comments on any public interest issues raised by the complaint or complainant's filing under section 210.8(b) of the Commission's Rules of Practice and......

  5. Electronic versus Traditional Storybooks: Relative Influence on Preschool Children's Engagement and Communication

    ERIC Educational Resources Information Center

    Moody, Amelia K; Justice, Laura M; Cabell, Sonia Q

    2010-01-01

    The purpose of this study was to examine children's reading engagement and communicative initiations when they were read storybooks in varying media and reading manners, with a focus on understanding the way electronic storybooks (e-storybooks) may affect young children's shared reading experiences. The reading behaviors of 25 preschool-aged…

  6. Electronic Communications Technologies and the Transition to College: Links to Parent-Child Attachment and Adjustment

    ERIC Educational Resources Information Center

    Sarigiani, Pamela A.; Trumbell, Jill M.; Camarena, Phame M.

    2013-01-01

    Electronic communications technologies (ECTs) help college students and parents remain in contact. Because recent reports have emphasized a link between ECTs, helicopter parenting, and autonomy issues, this study focused on the significance of contact patterns for attachment and student adjustment. First-semester college students (199 female, 81…

  7. Integration of Electronic Communication in Higher Education: Contributions of Faculty Computer Self-Efficacy.

    ERIC Educational Resources Information Center

    Kagima, Leah Keino; Hausafus, Cheryl O.

    2000-01-01

    This study examined relationships between faculty computer self-efficacy and integration of electronic communication when teaching. Results showed computer self-efficacy scores differed on age, gender, college, integration, and computer experience. Recommends faculty development efforts to increase self-efficacy by providing hands-on experiences…

  8. Operational implications of propagation models used in communications evaluation in tactical electronic warfare planning

    NASA Astrophysics Data System (ADS)

    Murray, J. P.

    1982-08-01

    Propagation models are used to estimate both desired and unwelcome signals in communications systems used in tactical military operations. The variability associated with propagation influences, particularly in the highly mobile and uncertain locales of representative scenarios, introduces unusual factors in the evaluation of simulation results. Practical constraints on resources that can be devoted to communications and jamming effects during simulation require various approximations. The several applications for which propagation models are used are identified and several descriptive classifications within which models may be evaluated are discussed. A series of performance measures popularly used in communications and electronic warfare planning are reviewed and are used as the basis for describing the implications which arise from the use of each class of models. Implications with regard to communications and jamming range, reliability, and detection range are discussed.

  9. UV-radiation-induced electron emission by hormones. Hypothesis for specific communication mechanisms

    NASA Astrophysics Data System (ADS)

    Getoff, Nikola

    2009-11-01

    The highlights of recently observed electron emission from electronically excited sexual hormones (17β-estradiol, progesterone, testosterone) and the phytohormone genistein in polar media are briefly reviewed. The electron yield, Q(e aq-), dependence from substrate concentration, hormone structure, polarity of solvent, absorbed energy and temperature are discussed. The hormones reactivity with e aq- and efficiency in electron transfer ensure them the ability to communicate with other biological systems in an organism. A hypothesis is presented for the explanation of the mechanisms of the distinct recognition of signals transmitted by electrons, originating from different types of hormones to receiving centres. Biological consequences of the electron emission in respect to cancer are mentioned.

  10. Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy.

    PubMed

    Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng

    2015-12-01

    The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials. PMID:26646862

  11. Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy

    SciTech Connect

    Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng

    2015-12-07

    The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials.

  12. FAST TRACK COMMUNICATION: Attosecond correlation dynamics during electron tunnelling from molecules

    NASA Astrophysics Data System (ADS)

    Walters, Zachary B.; Smirnova, Olga

    2010-08-01

    In this communication, we present an analytical theory of strong-field ionization of molecules, which takes into account the rearrangement of multiple interacting electrons during the ionization process. We show that such rearrangement offers an alternative pathway to the ionization of orbitals more deeply bound than the highest occupied molecular orbital. This pathway is not subject to the full exponential suppression characteristic of direct tunnel ionization from the deeper orbitals. The departing electron produces an 'attosecond correlation pulse' which controls the rearrangement during the tunnelling process. The shape and duration of this pulse are determined by the electronic structure of the relevant states, molecular orientation and laser parameters.

  13. Surface-plasmon enhanced photodetection at communication band based on hot electrons

    NASA Astrophysics Data System (ADS)

    Wu, Kai; Zhan, Yaohui; Wu, Shaolong; Deng, Jiajia; Li, Xiaofeng

    2015-08-01

    Surface plasmons can squeeze light into a deep-subwavelength space and generate abundant hot electrons in the nearby metallic regions, enabling a new paradigm of photoconversion by the way of hot electron collection. Unlike the visible spectral range concerned in previous literatures, we focus on the communication band and design the infrared hot-electron photodetectors with plasmonic metal-insulator-metal configuration by using full-wave finite-element method. Titanium dioxide-silver Schottky interface is employed to boost the low-energy infrared photodetection. The photodetection sensitivity is strongly improved by enhancing the plasmonic excitation from a rationally engineered metallic grating, which enables a strong unidirectional photocurrent. With a five-step electrical simulation, the optimized device exhibits an unbiased responsivity of ˜0.1 mA/W and an ultra-narrow response band (FWHM = 4.66 meV), which promises to be a candidate as the compact photodetector operating in communication band.

  14. Communications

    NASA Technical Reports Server (NTRS)

    Stouffer, Donald D.

    1990-01-01

    Communication in its many forms is a critical component for an effective Space Grant Program. Good communication is needed within individual Space Grant College/Consortia, for example between consortium affiliates and the consortium program office. Effective communication between the several programs, NASA Headquarters, and NASA field centers also is required. Further, communication among the above program elements, industry, local and state government, and the public also are necessary for meeting program objectives.

  15. Intramolecular Hydrogen Bonding in Substituted Aminoalcohols.

    PubMed

    Lane, Joseph R; Schrøder, Sidsel D; Saunders, Graham C; Kjaergaard, Henrik G

    2016-08-18

    The qualifying features of a hydrogen bond can be contentious, particularly where the hydrogen bond is due to a constrained intramolecular interaction. Indeed there is disagreement within the literature whether it is even possible for an intramolecular hydrogen bond to form between functional groups on adjacent carbon atoms. This work considers the nature of the intramolecular interaction between the OH (donor) and NH2 (acceptor) groups of 2-aminoethanol, with varying substitution at the OH carbon. Gas-phase vibrational spectra of 1-amino-2-methyl-2-propanol (BMAE) and 1-amino-2,2-bis(trifluoromethyl)-2-ethanol (BFMAE) were recorded using Fourier transform infrared spectroscopy and compared to literature spectra of 2-aminoethanol (AE). Based on the experimental OH-stretching frequencies, the strength of the intramolecular hydrogen bond appears to increase from AE < BMAE ≪ BFMAE. Non-covalent interaction analysis shows evidence of an intramolecular hydrogen bond in all three molecules, with the order of the strength of interaction matching that of experiment. The experimental OH-stretching vibrational frequencies were found to correlate well with the calculated kinetic energy density, suggesting that this approach can be used to estimate the strength of an intramolecular hydrogen bond. PMID:27447952

  16. Intramolecular circuits connected to N electrodes using a scattering matrix approach

    NASA Astrophysics Data System (ADS)

    Ami, S.; Joachim, C.

    2002-04-01

    The scattering matrix technique is extended to describe the electronic transport characteristics of intramolecular circuits driven in a ballistic or a tunnel transport regime. The circuit is assumed to be connected by N electrodes. As a working example, the electronic properties of a T-node circuit are presented leading to the design of an OR logic gate working in a ballistic regime. In the tunnel regime, only the ``node'' Kirchhoff law of circuit remains valid at the nodes of an intramolecular tunnel circuit and the electronic characteristics of the branches composing the circuit are mutually independent. It results in a difficult design of a logic OR intramolecular gate of high performance and stability, pointing out the urge for new architectures to implement complex logic functions inside a single molecule.

  17. Integration and test of high-speed transmitter electronics for free-space laser communications

    NASA Technical Reports Server (NTRS)

    Soni, Nitin J.; Lizanich, Paul J.

    1994-01-01

    The NASA Lewis Research Center in Cleveland, Ohio, has developed the electronics for a free-space, direct-detection laser communications system demonstration. Under the High-Speed Laser Integrated Terminal Electronics (Hi-LITE) Project, NASA Lewis has built a prototype full-duplex, dual-channel electronics transmitter and receiver operating at 325 megabit S per second (Mbps) per channel and using quaternary pulse-position modulation (QPPM). This paper describes the integration and testing of the transmitter portion for future application in free-space, direct-detection laser communications. A companion paper reviews the receiver portion of the prototype electronics. Minor modifications to the transmitter were made since the initial report on the entire system, and this paper addresses them. The digital electronics are implemented in gallium arsenide integrated circuits mounted on prototype boards. The fabrication and implementation issues related to these high-speed devices are discussed. The transmitter's test results are documented, and its functionality is verified by exercising all modes of operation. Various testing issues pertaining to high-speed circuits are addressed. A description of the transmitter electronics packaging concludes the paper.

  18. Local intelligent electronic device (IED) rendering templates over limited bandwidth communication link to manage remote IED

    DOEpatents

    Bradetich, Ryan; Dearien, Jason A; Grussling, Barry Jakob; Remaley, Gavin

    2013-11-05

    The present disclosure provides systems and methods for remote device management. According to various embodiments, a local intelligent electronic device (IED) may be in communication with a remote IED via a limited bandwidth communication link, such as a serial link. The limited bandwidth communication link may not support traditional remote management interfaces. According to one embodiment, a local IED may present an operator with a management interface for a remote IED by rendering locally stored templates. The local IED may render the locally stored templates using sparse data obtained from the remote IED. According to various embodiments, the management interface may be a web client interface and/or an HTML interface. The bandwidth required to present a remote management interface may be significantly reduced by rendering locally stored templates rather than requesting an entire management interface from the remote IED. According to various embodiments, an IED may comprise an encryption transceiver.

  19. Reversible Tuning of Interfacial and Intramolecular Charge Transfer in Individual MnPc Molecules.

    PubMed

    Zhong, Jian-Qiang; Wang, Zhunzhun; Zhang, Jia Lin; Wright, Christopher A; Yuan, Kaidi; Gu, Chengding; Tadich, Anton; Qi, Dongchen; Li, He Xing; Lai, Min; Wu, Kai; Xu, Guo Qin; Hu, Wenping; Li, Zhenyu; Chen, Wei

    2015-12-01

    The reversible selective hydrogenation and dehydrogenation of individual manganese phthalocyanine (MnPc) molecules has been investigated using photoelectron spectroscopy (PES), low-temperature scanning tunneling microscopy (LT-STM), synchrotron-based near edge X-ray absorption fine structure (NEXAFS) measurements, and supported by density functional theory (DFT) calculations. It is shown conclusively that interfacial and intramolecular charge transfer arises during the hydrogenation process. The electronic energetics upon hydrogenation is identified, enabling a greater understanding of interfacial and intramolecular charge transportation in the field of single-molecule electronics. PMID:26528623

  20. Linguistic Input, Electronic Media, and Communication Outcomes of Toddlers with Hearing Loss

    PubMed Central

    Ambrose, Sophie E.; VanDam, Mark; Moeller, Mary Pat

    2013-01-01

    Objectives The objectives of this study were to examine the quantity of adult words, adult-child conversational turns, and electronic media in the auditory environments of toddlers who are hard of hearing (HH) and to examine whether these variables contributed to variability in children’s communication outcomes. Design Participants were 28 children with mild to severe hearing loss. Full-day recordings of children’s auditory environments were collected within 6 months of their 2nd birthdays by utilizing LENA (Language ENvironment Analysis) technology. The system analyzes full-day acoustic recordings, yielding estimates of the quantity of adult words, conversational turns, and electronic media exposure in the recordings. Children’s communication outcomes were assessed via the receptive and expressive scales of the Mullen Scales of Early Learning at 2 years of age and the Comprehensive Assessment of Spoken Language at 3 years of age. Results On average, the HH toddlers were exposed to approximately 1400 adult words per hour and participated in approximately 60 conversational turns per hour. An average of 8% of each recording was classified as electronic media. However, there was considerable within-group variability on all three measures. Frequency of conversational turns, but not adult words, was positively associated with children’s communication outcomes at 2 and 3 years of age. Amount of electronic media exposure was negatively associated with 2-year-old receptive language abilities; however, regression results indicate that the relationship was fully mediated by the quantity of conversational turns. Conclusions HH toddlers who were engaged in more conversational turns demonstrated stronger linguistic outcomes than HH toddlers who were engaged in fewer conversational turns. The frequency of these interactions was found to be decreased in households with high rates of electronic media exposure. Optimal language-learning environments for HH toddlers include

  1. Communication.

    ERIC Educational Resources Information Center

    Online-Offline, 1998

    1998-01-01

    This theme issue on communication includes annotated listings of Web sites, CD-ROM and computer software, videos, books, and professional resources that deal with various methods of communication. Sidebars discuss mythology, photojournalism, sharing ideas on the Web, and songs of protest. Suggestions for class activities are also included. (LRW)

  2. Communication

    NASA Technical Reports Server (NTRS)

    Griner, James

    2010-01-01

    NASA s communication work for the UAS Command and Control area will build upon work currently being conducted under NASA Recovery Act funds. Communication portions of UAS NextGen ConOps, Stateof- the-Art assessment, and Gap Analysis. Preliminary simulations for UAS CNPC link scalability assessment. Surrogate UAS aircraft upgrades. This work will also leverage FY10 in-guide funding for communication link model development. UAS are currently managed through exceptions and are operating using DoD frequencies for line-of-sight (LOS) and satellite-based communications links, low-power LOS links in amateur bands, or unlicensed Instrument/Scientific/Medical (ISM) frequencies. None of these frequency bands are designated for Safety and Regularity of Flight. No radio-frequency (RF) spectrum has been allocated by the International Telecommunications Union (ITU) specifically for UAS command and control links, for either LOS or Beyond LOS (BLOS) communication.

  3. Communicating Ebola through social media and electronic news media outlets: A cross-sectional study.

    PubMed

    Househ, Mowafa

    2016-09-01

    Social media and electronic news media activity are an important source of information for the general public. Yet, there is a dearth of research exploring the use of Twitter and electronic news outlets during significant worldly events such as the recent Ebola Virus scare. The purpose of this article is to investigate the use of Twitter and electronic news media outlets in communicating Ebola Virus information. A cross-sectional survey of Twitter data and Google News Trend data from 30 September till 29 October, 2014 was conducted. Between 30 September and 29 October, there were approximately 26 million tweets (25,925,152) that contained the word Ebola. The highest number of correlated activity for Twitter and electronic news outlets occurred on 16 October 2014. Other important peaks in Twitter data occurred on 1 October, 6 October, 8 October, and 12 October, 2014. The main influencers of the Twitter feeds were news media outlets. The study reveals a relationship between electronic news media publishing and Twitter activity around significant events such as Ebola. Healthcare organizations should take advantage of the relationship between electronic news media and trending events on social media sites such as Twitter and should work on developing social media campaigns in co-operation with leading electronic news media outlets (e.g. CNN, Yahoo, Reuters) that can have an influence on social media activity. PMID:25656678

  4. Understanding Electronic Medical Record Adoption in the United States: Communication and Sociocultural Perspectives

    PubMed Central

    Kreps, Gary L; Polit, Stan

    2013-01-01

    Background This paper adopts a communication and sociocultural perspective to analyze the factors behind the lag in electronic medical record (EMR) adoption in the United States. Much of the extant research on this topic has emphasized economic factors, particularly, lack of economic incentives, as the primary cause of the delay in EMR adoption. This prompted the Health Information Technology on Economic and Clinical Health Act that allow financial incentives through the Centers of Medicare and Medicaid Services for many health care organizations planning to adopt EMR. However, financial incentives alone have not solved the problem; many new innovations do not diffuse even when offered for free. Thus, this paper underlines the need to consider communication and sociocultural factors to develop a better understanding of the impediments of EMR adoption. Objective The objective of this paper was to develop a holistic understanding of EMR adoption by identifying and analyzing the impact of communication and sociocultural factors that operate at 3 levels: macro (environmental), meso (organizational), and micro (individual). Methods We use the systems approach to focus on the 3 levels (macro, meso, and micro) and developed propositions at each level drawing on the communication and sociocultural perspectives. Results Our analysis resulted in 10 propositions that connect communication and sociocultural aspects with EMR adoption. Conclusions This paper brings perspectives from the social sciences that have largely been missing in the extant literature of health information technology (HIT) adoption. In doing so, it implies how communication and sociocultural factors may complement (and in some instances, reinforce) the impact of economic factors on HIT adoption. PMID:23612390

  5. Development and Integration of a Course in Electronic Communications for a New Engineering Technology Program at Valencia Community College.

    ERIC Educational Resources Information Center

    Byers, William S.

    This volume is a report of the development of the first course in a two-semester sequence in Electronic Communications, for a new degree program in Electric Engineering Technology at Valencia Community College, Orlando, Florida. Evolution of the program is described with comments relating the philosophy and importance of a communications sequence.…

  6. The Relationship of Electronic Grade Book Access to Student Achievement, Student Attendance, and Parent-Teacher Communication

    ERIC Educational Resources Information Center

    Mathern, Mark S.

    2009-01-01

    Increasing access to online databases from home has raised the value of computer use for retrieving student achievement information. This study's purpose was to examine the relationship of family use of an electronic reporting mechanism in the home to student achievement, attendance, and home-school communication. Using communication as a parent…

  7. 25 CFR 547.15 - What are the minimum technical standards for electronic data communications between system...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... multiplex access (as in cell phone technology). (c) Methodologies shall be used that will ensure the... data communications between system components? 547.15 Section 547.15 Indians NATIONAL INDIAN GAMING... communications between system components? This section provides minimum standards for electronic...

  8. 25 CFR 547.15 - What are the minimum technical standards for electronic data communications between system...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... multiplex access (as in cell phone technology). (c) Methodologies shall be used that will ensure the... data communications between system components? 547.15 Section 547.15 Indians NATIONAL INDIAN GAMING... communications between system components? This section provides minimum standards for electronic...

  9. 25 CFR 547.15 - What are the minimum technical standards for electronic data communications between system...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... multiplex access (as in cell phone technology). (c) Methodologies shall be used that will ensure the... data communications between system components? 547.15 Section 547.15 Indians NATIONAL INDIAN GAMING... communications between system components? This section provides minimum standards for electronic...

  10. An IIR adaptive electronic equalizer for polarization multiplexed fiber optic communication systems

    NASA Astrophysics Data System (ADS)

    Zeng, Xiang-Ye; Liu, Jian-Fei; Zhao, Qi-Da

    2011-09-01

    An electronic digital equalizer for polarization multiplex coherent fiber optic communication systems is designed to compensate polarization mode dispersion (PMD) and residual chromatic dispersion (CD) of transmission channel. The proposed equalizer is realized with fraction spaced infinite impulse response (IIR) butterfly structure with 21 feedforward taps and 2 feedback taps. Compared with finite impulse response (FIR) structure, this structure can reduce implementation complexity of hardware under the same condition. To keep track of the random variation of channel characteristics, the filter weights are updated by least mean square (LMS) algorithm. The simulation results show that the proposed equalizer can compensate residual chromatic dispersion (CD) of 1600 ps/nm and differential group delay (DGD) of 90 ps simultaneously, and also can increase the PMD and residual CD tolerance of the whole communication system.

  11. Long-Range Ruthenium-Amine Electronic Communication through the para-Oligophenylene Wire

    PubMed Central

    Shen, Jun-Jian; Zhong, Yu-Wu

    2015-01-01

    The studies of long-range electronic communication are hampered by solubility and potential-splitting issues. A “hybridized redox-asymmetry” method using a combination of organic and inorganic redox species is proposed and exemplified to overcome these two issues. Complexes 1(PF6)–6(PF6) (from short to long in length) with the organic redox-active amine and inorganic cyclometalated ruthenium termini bridged by the para-oligophenylene wire have been prepared. Complex 6 has the longest Ru-amine geometrical distance of 27.85 Å. Complexes 3(PF6) and 4(PF6) show lamellar crystal packing on the basis of a head-to-tail anti-parallelly aligned dimeric structure. Two redox waves are observed for all complexes in the potential region between +0.2 and +0.9 V vs Ag/AgCl. The electrochemical potential splitting is 410, 220, 143, 112, 107, and 105 mV for 1(PF6) through 6(PF6), respectively. Ruthenium (+2) to aminium (N•+) charge transfer transitions have been identified for the odd-electron compounds 12+–62+ by spectroelectrochemical measurements. The electronic communication between amine and ruthenium decreases exponentially with a decay slope of −0.137 Å−1. DFT calculations have been performed to complement these experimental results. PMID:26344929

  12. Surface-plasmon enhanced photodetection at communication band based on hot electrons

    SciTech Connect

    Wu, Kai; Zhan, Yaohui E-mail: xfli@suda.edu.cn; Wu, Shaolong; Deng, Jiajia; Li, Xiaofeng E-mail: xfli@suda.edu.cn

    2015-08-14

    Surface plasmons can squeeze light into a deep-subwavelength space and generate abundant hot electrons in the nearby metallic regions, enabling a new paradigm of photoconversion by the way of hot electron collection. Unlike the visible spectral range concerned in previous literatures, we focus on the communication band and design the infrared hot-electron photodetectors with plasmonic metal-insulator-metal configuration by using full-wave finite-element method. Titanium dioxide-silver Schottky interface is employed to boost the low-energy infrared photodetection. The photodetection sensitivity is strongly improved by enhancing the plasmonic excitation from a rationally engineered metallic grating, which enables a strong unidirectional photocurrent. With a five-step electrical simulation, the optimized device exhibits an unbiased responsivity of ∼0.1 mA/W and an ultra-narrow response band (FWHM = 4.66 meV), which promises to be a candidate as the compact photodetector operating in communication band.

  13. Long-Range Ruthenium-Amine Electronic Communication through the para-Oligophenylene Wire

    NASA Astrophysics Data System (ADS)

    Shen, Jun-Jian; Zhong, Yu-Wu

    2015-09-01

    The studies of long-range electronic communication are hampered by solubility and potential-splitting issues. A “hybridized redox-asymmetry” method using a combination of organic and inorganic redox species is proposed and exemplified to overcome these two issues. Complexes 1(PF6)-6(PF6) (from short to long in length) with the organic redox-active amine and inorganic cyclometalated ruthenium termini bridged by the para-oligophenylene wire have been prepared. Complex 6 has the longest Ru-amine geometrical distance of 27.85 Å. Complexes 3(PF6) and 4(PF6) show lamellar crystal packing on the basis of a head-to-tail anti-parallelly aligned dimeric structure. Two redox waves are observed for all complexes in the potential region between +0.2 and +0.9 V vs Ag/AgCl. The electrochemical potential splitting is 410, 220, 143, 112, 107, and 105 mV for 1(PF6) through 6(PF6), respectively. Ruthenium (+2) to aminium (N•+) charge transfer transitions have been identified for the odd-electron compounds 12+-62+ by spectroelectrochemical measurements. The electronic communication between amine and ruthenium decreases exponentially with a decay slope of -0.137 Å-1. DFT calculations have been performed to complement these experimental results.

  14. Long-Range Ruthenium-Amine Electronic Communication through the para-Oligophenylene Wire.

    PubMed

    Shen, Jun-Jian; Zhong, Yu-Wu

    2015-01-01

    The studies of long-range electronic communication are hampered by solubility and potential-splitting issues. A "hybridized redox-asymmetry" method using a combination of organic and inorganic redox species is proposed and exemplified to overcome these two issues. Complexes 1(PF6)-6(PF6) (from short to long in length) with the organic redox-active amine and inorganic cyclometalated ruthenium termini bridged by the para-oligophenylene wire have been prepared. Complex 6 has the longest Ru-amine geometrical distance of 27.85 Å. Complexes 3(PF6) and 4(PF6) show lamellar crystal packing on the basis of a head-to-tail anti-parallelly aligned dimeric structure. Two redox waves are observed for all complexes in the potential region between +0.2 and +0.9 V vs Ag/AgCl. The electrochemical potential splitting is 410, 220, 143, 112, 107, and 105 mV for 1(PF6) through 6(PF6), respectively. Ruthenium (+2) to aminium (N(•+)) charge transfer transitions have been identified for the odd-electron compounds 1(2+)-6(2+) by spectroelectrochemical measurements. The electronic communication between amine and ruthenium decreases exponentially with a decay slope of -0.137 Å(-1). DFT calculations have been performed to complement these experimental results. PMID:26344929

  15. Intramolecular Dehydrogenative Coupling of 2,3-Diaryl Acrylic Compounds: Access to Substituted Phenanthrenes.

    PubMed

    Gupta, Vijay; Rao, V U Bhaskara; Das, Tamal; Vanka, Kumar; Singh, Ravi P

    2016-07-01

    A simple, facile, and environmentally benign intramolecular dehydrogenative coupling of various 1,2-diarylethylenes for the synthesis of phenanthrenes in excellent yield has been described. This new methodology uses ceric ammonium nitrate (CAN) as a promoter at room temperature and has been extended to intermolecular synthesis of biaryl compounds. The electron transfer from methoxyarene to cerium leads to cationic radical formation, which further proceeds to intramolecular coupling. Preliminary mechanistic investigation by EPR spectroscopy and density functional theory calculation suggested a similar view. PMID:27232691

  16. Organocatalyzed Intramolecular Carbonyl-Ene Reactions.

    PubMed

    Dahlmann, Heidi A; McKinney, Amanda J; Santos, Maria P; Davis, Lindsey O

    2016-01-01

    An organocatalyzed intramolecular carbonyl-ene reaction was developed to produce carbocyclic and heterocyclic 5- and 6-membered rings from a citronellal-derived trifluoroketone and a variety of aldehydes. A phosphoramide derivative was found to promote the cyclization of the trifluoroketone, whereas a less acidic phosphoric acid proved to be a superior catalyst for the aldehyde substrates. PMID:27258238

  17. Intramolecular alpha–Glucosaminidation: Synthesis of Mycothiol

    PubMed Central

    Ajayi, Kehinde; Thakur, Vinay V.; Lapo, Robert C.; Knapp, Spencer

    2010-01-01

    A protected cyclitol aglycon was tethered to an (N-arylsulfonyl)glucosamine donor by a methylene linker; the exclusively alpha-selective intramolecular glycosyation reaction was then initiated by electrophilic activation of the thioglycoside donor portion. Further transformations of the glycosylation product to give the M. tuberculosis detoxifier mycothiol and its oxidized congener, the disulfide mycothione, are detailed. PMID:20443569

  18. Intramolecular strain coordinates kinesin stepping behavior along microtubules

    PubMed Central

    Yildiz, Ahmet; Tomishige, Michio; Gennerich, Arne; Vale, Ronald D.

    2008-01-01

    SUMMARY Kinesin advances 8 nm along a microtubule per ATP hydrolyzed, but the mechanism responsible for coordinating the enzymatic cycles of kinesin’s two identical motor domains remains unresolved. Here, we have tested whether such coordination is mediated by intramolecular tension generated by the “neck linkers”, mechanical elements that span between the motor domains. When tension is reduced by extending the neck linkers with artificial peptides, the coupling between ATP hydrolysis and forward stepping is impaired and motor’s velocity decreases as a consequence. However, speed recovers to nearly normal levels when external tension is applied by an optical trap. Remarkably, external load also induces bidirectional stepping of an immotile kinesin that lacks its mechanical element (neck linker) and fuel (ATP). Our results indicate that the kinesin motor domain senses and responds to strain in a manner that facilitates its plus-end-directed stepping and communication between its two motor domains. PMID:18805095

  19. Communications

    NASA Technical Reports Server (NTRS)

    Hathorn, S.

    1985-01-01

    An overview of NASA's Thin Route satellite telecommunication project is presented. Thin Route employs applications technology satellites (ATS) in place of more costly commercial multi- transponder telecommunications satellites. This system allows remote and underdeveloped areas to communicate with the outside world for purposes of obtaining medical assistance among other things. The system represents a substantial cost saving over commercial systems.

  20. Communications

    ERIC Educational Resources Information Center

    Bailenson, Jeremy; Buzzanell, Patrice; Deetz, Stanley; Tewksbury, David; Thompson, Robert J.; Turow, Joseph; Bichelmeyer, Barbara; Bishop, M. J.; Gayeski, Diane

    2013-01-01

    Scholars representing the field of communications were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Jeremy Bailenson, Patrice Buzzanell, Stanley Deetz, David Tewksbury, Robert J. Thompson, and…

  1. Electronic communication based interventions for hazardous young drinkers: A systematic review.

    PubMed

    O'Rourke, L; Humphris, G; Baldacchino, A

    2016-09-01

    Previous reviews have specifically looked at computer-based or Internet-based approaches. However, there has been no systematic review focused upon electronic communication based interventions for hazardous young drinkers. Out of 3298 relevant citations, 13 papers consisting of 11 studies met the inclusion criteria. Effectiveness of intervention delivery was assessed using behavioural outcomes. Eight papers delivered interventions using the Web, three implemented text messaging, one used a mobile phone app and the remaining paper used a social networking site. The ability to provide personalized electronic feedback resulted in a reduction in alcohol consumption, frequency of binge drinking, and drinking in a non-risky way. However, intervention length did not appear to have an impact on overall effectiveness. Usage of text messaging and Social Network Sites (SNS) increased accessibility and ease of engaging in an intervention that is appealing and acceptable for young adults. PMID:27453570

  2. Intramolecular energy transfer in fullerene pyrazine dyads

    SciTech Connect

    Guldi, D.M.; Torres-Garcia, G.; Mattay, J.

    1998-11-26

    Excited-state properties of three different pyrazine derivatives 4--6 were probed by emission and transient absorption spectroscopy. They display emission maxima at 464 (4), 417 (5), and 515 nm (6) that are red-shifted with respect to their strong UV ground-state absorption and formed with overall quantum yields ({Phi}) of 0.156, 0.22, and 0.13, respectively. Once photoexcited, these triplet excited pyrazines undergo rapid intermolecular energy transfer to a monofunctionalized fullerene derivative (7) with bimolecular rate constants ranging from 3.64 {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1} (6) to 1.1 {times} 10{sup 10} M{sup {minus}1} s{sup {minus}1} (4). The product of these bimolecular energy-transfer reactions is in all cases the fullerene triplet excited state. Functionalization of pristine C{sub 60} with the investigated pyrazine derivatives promotes the UV-vis absorption characteristics and, in turn, improves the light-harvesting efficiency of the resulting dyads 1--3 relative to pristine C{sub 60}. Photoexcitation of the pyrazine moieties in dyads 1--3 leads to the formation of their singlet excited states. In contrast to the pyrazine models, photoexcitation of dyad 1--3 is followed by rapid intramolecular deactivation processes of the latter via energy transfer to the fullerene ground state with half-lives between 37 and 100 ps. In turn, energy transfer transforms the short-lived and moderately redox-active singlet excited states of pyrazine into the highly reactive fullerene triplet excited state. The latter is found to produce effectively singlet oxygen ({sup 1}O{sub 2}) with quenching rate constants for 1--3 of (1--1.5) {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1}. Similarly, reductive quenching of the triplet excited states in dyads 1--3 via electron transfer with diazabicyclooctane (DABCO) occurs with rate constants of 5.2--9.4 {times} 10{sup 7} M{sup {minus}1} s{sup {minus}1}.

  3. Electronics design of a multi-rate DPSK modem for free-space optical communications

    NASA Astrophysics Data System (ADS)

    Rao, H. G.; Browne, C. A.; Caplan, D. O.; Carney, J. J.; Chavez, M. L.; Fletcher, A. S.; Fitzgerald, J. J.; Kaminsky, R. D.; Lund, G.; Hamilton, S. A.; Magliocco, R. J.; Mikulina, O. V.; Murphy, R. J.; Seaver, M. M.; Scheinbart, M. S.; Spellmeyer, N. W.; Wang, J. P.

    2014-03-01

    We have designed and experimentally demonstrated a radiation-hardened modem suitable for NASA's Laser Communications Relay Demonstration. The modem supports free-space DPSK communication over a wide range of channel rates, from 72 Mb/s up to 2.88 Gb/s. The modem transmitter electronics generate a bursty DPSK waveform, such that only one optical modulator is required. The receiver clock recovery is capable of operating over all channel rates at average optical signal levels below -70 dBm. The modem incorporates a radiation-hardened Xilinx Virtex 5 FPGA and a radiation-hardened Aeroflex UT699 CPU. The design leverages unique capabilities of each device, such as the FPGA's multi-gigabit transceivers. The modem scrubs itself against radiation events, but does not require pervasive triple-mode redundant logic. The modem electronics include automatic stabilization functions for its optical components, and software to control its initialization and operation. The design allows the modem to be put into a low-power standby mode.

  4. Organic Chemistry Online: Building Collaborative Learning Communities through Electronic Communication Tools

    NASA Astrophysics Data System (ADS)

    Glaser, Rainer E.; Poole, Melissa J.

    1999-05-01

    How do we make the undergraduate "large lecture" class seem like a small learning community? How can we utilize the new computer-mediated communication tools on the Internet to enhance communication and engage students in active learning? In this article, we report on the use of group research projects in an undergraduate course in organic chemistry to build small learning communities. Students engaged in group research projects via online resources and developed reports that were published online. They also worked together in groups to review the online reports of their peers. This work was facilitated by use of electronic media, including the course Web site, email, and an electronic discussion list. The resulting projects far exceeded our expectations. Students reported that the process of collaborative group work was beneficial for studying as well as for project work. Future plans include refinement of the research project assignment, development of an automated Web tool for reporting and calculating peer review scores, and refinement of the course evaluation tools.

  5. The Impact of Electronic Health Records on Healthcare Professional's Beliefs and Attitudes toward Face to Face Communication

    ERIC Educational Resources Information Center

    Nickles, Kenneth Patrick

    2012-01-01

    The impact of electronic health records on healthcare professional's beliefs and attitudes toward face to face communication during patient and provider interactions was examined. Quantitative survey research assessed user attitudes towards an electronic health record system and revealed that healthcare professionals from a wide range of…

  6. Intramolecular interactions in the polar headgroup of sphingosine: serinol† †Electronic supplementary information (ESI) available: Ab initio parameters for serinol conformers within 1000 cm–1, measured transition frequencies, typical a-type transition for conformer aa1, interconversion barriers and possible tunnelling pathways. See DOI: 10.1039/c5cc09423b Click here for additional data file.

    PubMed Central

    Loru, Donatella; Peña, Isabel; Alonso, José L.

    2016-01-01

    The intramolecular interactions in the lipid sphingosine have been elucidated through the investigation of the amino alcohol serinol which mimics its polar headgroup. Intricate networks of intramolecular hydrogen bonds involving the hydroxyl groups and the amino group contribute to the stabilisation of five different conformations observed in the broadband rotational spectrum. PMID:26727395

  7. Intermediate State Dependence of Intramolecular Vibrations in Photoactive Yellow Protein

    NASA Astrophysics Data System (ADS)

    Deng, Yanting; Xu, Mengyang; Niessen, Katherine; Schmidt, Marius; Markelz, Andrea

    Photoactive proteins provide a testbed for the role of long-range collective motions in protein function. Long-range intramolecular vibrations of the protein scaffold may provide efficient energy relaxation, enhancement of chromophore vibrations that promote structural transitions and assistance in electron energy transfer. Photoactive yellow protein (PYP) is a cytoplasmic photocycling protein associated with the negative phototactic response to blue light in halohodospira halophile. We measure the intramolecular vibrations of PYP using crystal anisotropy terahertz microscopy (CATM) as a function of photoexcitation. Room temperature CATM measurements are performed in the dark and with continuous illumination at 488 nm, which is found to result in an approximately 20% steady photoexcited state (pB). We find a decrease in anisotropic absorption in frequency range 20-60 cm-1 with photoexcitation. This result may be due to an increase in sample disorder associated with the structural change in pB state. We compare the measured and calculated spectra using molecular dynamics and normal mode/quasiharmonic analysis to identify the nature of the motions giving rise to the resonant absorption bands.

  8. Provider-to-Provider Electronic Communication in the Era of Meaningful Use: A Review of the Evidence

    PubMed Central

    Walsh, Colin; Siegler, Eugenia L; Cheston, Erin; O'Donnell, Heather; Collins, Sarah; Stein, Daniel; Vawdrey, David K.; Stetson, Peter D.

    2014-01-01

    Background Electronic communication between providers occurs daily in clinical practice but has not been well studied. Purpose To assess the impact of provider-to-provider electronic communication tools on communication and healthcare outcomes through literature review. Data sources OVID Medline, Pubmed, Google Scholar, CINAHL, and Academic Search Premier. Study Selection Publication in English language peer-reviewed journals. Studies provided quantitative provider-to-provider communication data, provider satisfaction statistics, or EHR communication data. Data Extraction Literature review. Data Synthesis Two reviewers conducted the title review to determine eligible studies from initial search results. Three reviewers independently reviewed titles, abstracts, and full text (where appropriate) against inclusion and exclusion criteria. Limitations Small number of eligible studies; few described trial design (20%). Homogeneous provider-type (physicians). English-only studies. Conclusions Of twenty-five included studies, all focused on physicians; most were observational (68%). Most (60%) described electronic specialist referral tools. Although overall use has been measured, there were no studies of the effectiveness of intra-EHR messaging. Literature describing the effectiveness of provider-to-provider electronic communications is sparse and narrow in scope. Complex care, such as that envisioned for the Patient Centered Medical Home, necessitates further research. PMID:24101544

  9. Direct Observation of Cascade of Photoinduced Ultrafast Intramolecular Charge Transfer Dynamics in Diphenyl Acetylene Derivatives: Via Solvation and Intramolecular Relaxation.

    PubMed

    Karunakaran, Venugopal; Das, Suresh

    2016-07-21

    Interaction of light with electron donor-acceptor π-conjugated systems leading to intramolecular charge transfer (ICT) plays an essential role in transformation of light energy. Here the cascade of photoinduced ICT processes is directly observed by investigating the excited state relaxation dynamics of cyano and mono/di methoxy substituted diphenyl acetylene derivatives using femtosecond pump-probe spectroscopy and nanosecond laser flash photolysis. The femtosecond transient absorption spectra of the chromophores upon ultrafast excitation reveal the dynamics of intermediates involved in transition from initially populated Frank-Condon state to local excited state (LE). It also provides the dynamic details of the transition from the LE to the charge transfer state yielding the formation of the radical ions. Finally, the charge transfer state decays to the triplet state by geminate charge recombination. The latter dynamics are observed in the nanosecond transient absorption spectra. It is found that excited state relaxation pathways are controlled by different stages of solvation and intramolecular relaxation depending on the solvent polarity. The twisted ICT state is more stabilized (978 ps) in acetonitrile than cyclohexane where major components of transient absorption originate from the S1 state. PMID:27347705

  10. Aptamer switch probe based on intramolecular displacement.

    PubMed

    Tang, Zhiwen; Mallikaratchy, Prabodhika; Yang, Ronghua; Kim, Youngmi; Zhu, Zhi; Wang, Hui; Tan, Weihong

    2008-08-27

    A novel aptamer-based molecular probe design employing intramolecular signal transduction is demonstrated. The probe is composed of three elements: an aptamer, a short, partially cDNA sequence, and a PEG linker conjugating the aptamer with the short DNA strand. We have termed this aptamer probe an "aptamer switch probe", or ASP. The ASP design utilizes both a fluorophore and a quencher which are respectively modified at the two termini of the ASP. In the absence of the target molecule, the short DNA will hybridize with the aptamer, keeping the fluorophore and quencher in close proximity, thus switching off the fluorescence. However, when the ASP meets its target, the binding between the aptamer and the target molecule will disturb the intramolecular DNA hybridization, move the quencher away from the fluorophore, and, in effect, switch on the fluorescence. Both ATP and human alpha-thrombin aptamers were engineered to demonstrate this design, and both showed that fluorescence enhancement could be quantitatively mediated by the addition of various amounts of target molecules. Both of these ASPs presented excellent selectivity and prompt response toward their targets. With intrinsic advantages resulting from its intramolecular signal transduction architecture, the ASP design holds promising potential for future applications, such as biochip and in situ imaging, which require reusability, excellent stability, prompt response, and high sensitivity. PMID:18680291

  11. Communications.

    ERIC Educational Resources Information Center

    Steele, Colin; And Others

    1986-01-01

    Five brief articles examine new library technologies and physical problems; potential health hazards posed by frequent use of photocopiers; psychological deterrence of electronic security systems; quality control of cooperative cataloging in a library network; and the billing system designed and programed for a medical library. Two articles…

  12. Empirical models of the electron concentration of the ionosphere and their value for radio communications purposes

    SciTech Connect

    Dudeney, J.R.; Kressman, R.I.

    1986-06-01

    Criteria for the development of ionosphere electron concentration vertical profile empirical models for radio communications purposes are discussed and used to evaluate and compare four contemporary schemes. Schemes must be optimized with respect to quality of profile match, availability and simplicity of the external data required for profile specification, and numerical complexity, depending on the application. It is found that the Dudeney (1978) scheme provides the best general performance, while the Booker (1977) technique is optimized for precision radio wave studies where an observed profile is available. The CCIR (Bradley and Dudeney, 1973) scheme performance is found to be inferior to the previous two, and should be superceded except where mathematical simplicity is prioritized. The International Reference Ionosphere profile is seen to have significant disadvantages with respect to all three criteria. 17 references.

  13. Empirical models of the electron concentration of the ionosphere and their value for radio communications purposes

    NASA Astrophysics Data System (ADS)

    Dudeney, J. R.; Kressman, R. I.

    1986-06-01

    Criteria for the development of ionosphere electron concentration vertical profile empirical models for radio communications purposes are discussed and used to evaluate and compare four contemporary schemes. Schemes must be optimized with respect to quality of profile match, availability and simplicity of the external data required for profile specification, and numerical complexity, depending on the application. It is found that the Dudeney (1978) scheme provides the best general performance, while the Booker (1977) technique is optimized for precision radio wave studies where an observed profile is available. The CCIR (Bradley and Dudeney, 1973) scheme performance is found to be inferior to the previous two, and should be superceded except where mathematical simplicity is prioritized. The International Reference Ionosphere profile is seen to have significant disadvantages with respect to all three criteria.

  14. Social Media and Oncology: The Past, Present, and Future of Electronic Communication Between Physician and Patient.

    PubMed

    Lewis, Mark A; Dicker, Adam P

    2015-10-01

    The relationship between patient and physician is in flux with the advent of electronic media that are advancing and enhancing communication. We perform a retrospective, current, and forward-looking examination of the technologies by which information is exchanged within the healthcare community. The evolution from e-mail and listservs to blogs and the modern social networks is described, with emphasis on the advantages and pitfalls of each medium, especially in regard to maintaining the standards of privacy and professionalism to which doctors are held accountable. We support the use of contemporary platforms like Twitter and Facebook for physicians to establish themselves as trustworthy online sources of medical knowledge, and anticipate ongoing collaboration between researchers, patients, and their advocates in trial design and accrual. PMID:26433557

  15. Terahertz oscillators and receivers using electron devices for high-capacity wireless communication

    NASA Astrophysics Data System (ADS)

    Suzuki, Safumi; Asada, Masahiro

    2015-05-01

    Recent progress in room-temperature resonant-tunneling-diode (RTD) terahertz (THz) oscillators and high-electron-mobility- transistor (HEMT) THz receivers is reported in this paper. In this study, oscillations up to 1.86 THz were obtained using an optimized antenna and RTD. Using a two-element oscillator array, high output power of 0.6 mW at 620 GHz was obtained. THz communication up to 3 Gbps was demonstrated. A structure for high-speed direct modulation was fabricated, and the intensity modulation up to 30 GHz was achieved. A novel oscillator structure was proposed and fabricated for extraction of output power without using a Si lens. A short-gate InGaAs HEMT detector integrated with a broadband bow-tie antenna was fabricated, and a high current sensitivity of ~5 A/W was obtained at 280 GHz.

  16. Completeness and Timeliness of Electronic vs. Conventional Laboratory Reporting for Communicable Disease Surveillance—Oklahoma, 2011

    PubMed Central

    Williams, Jean; Lee, Anthony; Bradley, Kristy K.

    2014-01-01

    Objectives The Health Information Technology for Economic and Clinical Health (HITECH) Act encourages the meaningful use of certified electronic health record technology. A HITECH-compliant core component is nationwide electronic laboratory reporting (ELR) implementation for communicable disease surveillance. In Oklahoma, laboratories with ≥400 positive tests/year for reportable diseases must use ELR. Of 18 such laboratories, two have adopted ELR. We compared completeness and timeliness of ELR reports from these two laboratories with conventional reports from all other Oklahoma laboratories. Methods We retrospectively reviewed confirmed reportable disease cases for January 1–December 31, 2011, excluding tuberculosis, hepatitis, sexually transmitted infections, diseases without laboratory diagnoses, and immediately reportable diseases. Probable reportable tickborne disease cases were included. We compared ELR with conventional reporting (i.e., mail, fax, telephone, and Internet). We assessed data completeness based on eight demographic and two laboratory fields in each disease report and timeliness by percentage of cases reported in ≤1 business day. Results Overall, 1,867 reports met the inclusion criteria; 24% of these reports had been submitted by ELR. Data completeness was 90% for ELR and 95% for conventional reporting. Patient addresses accounted for 97% of the missing data fields for ELR reports. Timeliness was 91% for ELR and 87% for conventional reports. Conclusions Although early in the transition to ELR compliance in Oklahoma, ELR has already yielded improved timeliness for communicable disease surveillance. However, ELR did not yield more complete reports than conventional reporting. Requiring specific demographic data fields for ELR reports can improve the completeness of ELR. PMID:24791024

  17. Electronic Communications and Home Blood Pressure Monitoring (e-BP) study: Design, delivery, and evaluation framework

    PubMed Central

    Green, Beverly B.; Ralston, James D.; Fishman, Paul A.; Catz, Sheryl L.; Cook, Andrea; Carlson, Jim; Tyll, Lynda; Carrell, David; Thompson, Robert S.

    2009-01-01

    Background Randomized controlled trials have provided unequivocal evidence that treatment of hypertension decreases mortality and major disability from cardiovascular disease; however, blood pressure remains inadequately treated in most affected individuals. This large gap continues despite the facts that more than 90% of adults with hypertension have health insurance, and hypertension is the leading cause of visits to the doctor. New approaches are needed to improve hypertension care. Objectives The Electronic Communications and Home Blood Pressure Monitoring (e-BP) study is a three-arm randomized controlled trial designed to determine whether care based on the Chronic Care Model and delivered over the Internet improves hypertension care. The primary study outcomes are systolic, diastolic, and blood pressure control; secondary outcomes are medication adherence, patient self-efficacy, satisfaction and quality of life, and healthcare utilization and costs. Methods Hypertensive patients receiving care at Group Health medical centers are eligible if they have uncontrolled blood pressure on two screening visits and access to the Web and an e-mail address. Study participants are randomly assigned to three intervention groups: (a) usual care; (b) home blood pressure monitoring receipt and proficiency training on its use and the Group Health secure patient website (with secure e-mail access to their healthcare provider, access to a shared medical record, prescription refill and other services); or (c) this plus pharmacist care management (collaborative care management between the patient, the pharmacist, and the patient’s physician via a secure patient website and the electronic medical record). Conclusion We will determine whether a new model of patient-centered care that leverages Web communications, self-monitoring, and collaborative care management improves hypertension control. If this model proves successful and cost-effective, similar interventions could be used

  18. Intramolecular energy transfer reactions in polymetallic

    SciTech Connect

    Petersen, J.

    1990-11-01

    This report is concerned with intramolecular, energy-transfer reactions. The concept of preparing synthetically a complex molecular species, capable of absorbing a photon at one metal center (antenna fragment), transferring that energy to a second metal center (reactive fragment) via a bridging ligand was first reported by our group in 1979. It is now apparent that a major emphasis in inorganic chemistry in the future will involve these types of molecular ensembles. Complexes discussed include Rh, Ru, and Cu complexes. 23 refs., 14 tabs.

  19. Globalization, Information and Communication Technologies, and the Prospect of a "Global Village": Promises of Inclusion or Electronic Colonization?

    ERIC Educational Resources Information Center

    Zembylas, Michalinos; Vrasidas, Charalambos

    2005-01-01

    This paper discusses the reciprocal relationships among globalization, information and communication technologies (ICT), and the prospect of a "global village". The current metaphor of a "global village" (regardless of physical access to ICT) is problematic, and can be interpreted as a form of electronic colonization. However, through such…

  20. Scholarly but Relevant: A Comparison of Topic Frequency between "Journalism Quarterly,""Journal of Broadcasting & Electronic Media," and RTNDA "Communicator."

    ERIC Educational Resources Information Center

    Ozmun, David

    A study compared the topics addressed in a professional trade publication, the RTNDA (Radio and Television News Directors Association) "Communicator," with topics specifically addressing broadcast news in the scholarly journals "Journalism Quarterly" and "Journal of Broadcasting and Electronic Media." The purpose of the research was to help…

  1. Internal Stark effect mediates intramolecular excited-state proton transfer in 3-hydroxyflavone derivatives

    NASA Astrophysics Data System (ADS)

    Klymchenko, Andriy S.; Demchenko, Alexander P.

    2002-12-01

    Internal Stark effect in electronic spectra is the effect that is observed when the electronic bands shift udner the influence of promixal charges. In order to study the possible involvement of this effect in modulating the intramolecular proton transfer reactions in the excited state, we designed and studied several derivatives of 3-hydroxyflavone. They include the species containing neutral and positively charged substituents in 6 position of chromone ring. These compounds were studied in solvents of different polarities. In these experiments the shifts of both normal and tautomer flurosence bands are clearly observed in a manner predicted by Stark effect theory. In addition, a dramatic effect of suppression by introduced charge of intramolecular excited-state proton transfer was observed.

  2. Utilising tetraphenylethene as a dual activator for intramolecular charge transfer and aggregation induced emission.

    PubMed

    Zhang, Guo-Feng; Aldred, Matthew P; Gong, Wen-Liang; Li, Chong; Zhu, Ming-Qiang

    2012-08-11

    We report a simple design and synthesis of a donor-acceptor tetraphenylethene-naphthalimide (TPE-NI) dyad, in which TPE acts both as an electron-donor for intramolecular charge transfer (ICT) and activator for aggregation induced emission (AIE). Strong solvent-dependent photoluminescence covering almost the whole visible spectrum and AIE in its nanoparticle state compared to its solution state are demonstrated. PMID:22745935

  3. A near infrared colorimetric and fluorometric probe for organophosphorus nerve agent mimics by intramolecular amidation.

    PubMed

    Hu, Xiao-Xiao; Su, Yue-Ting; Ma, Yun-Wei; Zhan, Xin-Qi; Zheng, Hong; Jiang, Yun-Bao

    2015-10-21

    A near infrared probe for sensitive colorimetric and fluorimetric detection of nerve agent mimics, DCP and DCNP, was reported based on the activation of a carboxylic acid group by the mimics to conduct an intramolecular amidation reaction in the heptamethine chromophore, where its absorption or excitation maximum wavelength could be greatly red-shifted by attenuating the electron-donating ability of the amine group in the bridgehead site of heptamethine cyanine. PMID:26323249

  4. A Chiral Thiourea as a Template for Enantioselective Intramolecular [2 + 2] Photocycloaddition Reactions

    PubMed Central

    2016-01-01

    A chiral (1R,2R)-diaminocyclohexane-derived bisthiourea was found to exhibit a significant asymmetric induction in the intramolecular [2 + 2] photocycloaddition of 2,3-dihydropyridone-5-carboxylates. Under optimized conditions, the reaction was performed with visible light employing 10 mol % of thioxanthone as triplet sensitizer. Due to the different electronic properties of its carbonyl oxygen atoms, a directed binding of the substrate to the template is possible, which in turn enables an efficient enantioface differentiation. PMID:27258626

  5. Catalytic, Enantioselective, Intramolecular Carbosulfenylation of Olefins. Preparative and Stereochemical Aspects

    PubMed Central

    Denmark, Scott E.; Jaunet, Alex

    2014-01-01

    The first catalytic, enantioselective, intramolecular carbosulfenylation of isolated alkenes with aromatic nucleophiles is described. The combination of N-phenylsulfenylphthalimide, a chiral selenophosphoramide derived from BINAM, and ethanesulfonic acid as a co-catalytic Brønsted acid induced an efficient and selective cyclofunctionalization of various alkenes (aliphatic and aromatic) tethered to a 3,4-methylenedioxyphenyl ring. Under these conditions, 6-phenylthio-5,6,7,8-tetrahydronaphthalenes are formed diastereospecifically in good yields (50–92%) and high enantioselectivities (71:29 – 97:3 er). E-Alkenes reacted much more rapidly and with much higher selectivity than Z-alkenes, whereas electron rich alkenes reacted more rapidly but with comparable selectivity to electron-neutral alkenes and electron deficient alkenes. The Brønsted acid played a critical role in effecting reproducible enantioselectivity. A model for the origin of enantioselectivity and the dependence of rate and selectivity on alkene structure is proposed along with a rationale for the site selectivity in reactions with mono-activated arene nucleophiles. PMID:24328051

  6. Anomalous ligand effect in gold(I)-catalyzed intramolecular hydroamination of alkynes.

    PubMed

    Gaggioli, Carlo Alberto; Ciancaleoni, Gianluca; Biasiolo, Luca; Bistoni, Giovanni; Zuccaccia, Daniele; Belpassi, Leonardo; Belanzoni, Paola; Tarantelli, Francesco

    2015-04-01

    We analyzed the ligand electronic effect in a gold(I)-catalyzed intramolecular alkyne hydroamination, through a DFT and charge-displacement function (CDF) study. We found that, in the presence of π-electron conjugation between the alkyne and the nucleophilic functionality, electron poor ligands modify the coordination mode and the geometric parameters of the substrate in such a way that, contrary to expectations, the activation barrier of the nucleophilic attack increases. This remarkable effect is due to the competition between alkyne activation and nucleophile deactivation. The general relevance of these findings is highlighted. PMID:25738820

  7. High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

    SciTech Connect

    Niu, B.

    1992-09-01

    High resolution He I[alpha] photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a soft'' mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.

  8. High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

    SciTech Connect

    Niu, B.

    1992-09-01

    High resolution He I{alpha} photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the molecular cations. This study reveals much more vibrational structural detail in the first electronic excited state of H2CO cations. The first electronic excited state of H2CO cations may have nonplanar equilibrium geometry. Strong isotope effects on vibronic (vibrational) coupling are observed in the second electronic excited state of H2CO. Vibrational autocorrelation functions are calculated for all four observed electronic states of H2CO. The correlation function of the first electronic excited state of H2CO shows a slow decay rate on the femtosecond time scale. The ultrafast decay of the H2CO cations in the third electronic excited state implies that dissociation and intramolecular processes are the main decay pathways. The present spectra of the ground states of ketene cations have more fine structure than before. The AIEs of the first and fifth excited states are determined unambiguously more accurately. The doublet-like fine structures present in the lint excited state of ketene implies the excitation of a ``soft`` mode not observed before. The vibrational autocorrelation functions are calculated for 4 of the 6 observed electronic states. The dynamics of the ground states of the cations are characterized by a wave packet oscillating with small amplitude around the minimum on the upper PES. The decay dynamics of the first and the fifth excited states of ketene are characterized by ultra-fast intramolecular processes like predissociation.

  9. Simple intramolecular model potentials for water

    SciTech Connect

    Dang, L.X.; Pettitt, B.M.

    1987-06-04

    An effective intramolecular potential is presented for use in conjunction with existing three-site models of water. Two commonly used internal geometries were fit to the same form yielding slightly different parametrizations. By including a Urey-Bradley-like term in an otherwise standard molecular mechanics form it was found that the experimental transition frequencies of water monomer can be reproduced accurately. Good qualitative agreements for spectral shifts were subsequently found for the models in condensed-phase applications. Harmonic analysis of clusters indicates good qualitative agreement with experimental environmental shifts in frequencies at low temperatures for these models. This model should be useful for a wide variety of applications including simulations of biopolymers and ionic solutions.

  10. Are intramolecular frustrated Lewis pairs also intramolecular catalysts? A theoretical study on H2 activation.

    PubMed

    Zeonjuk, Lei Liu; St Petkov, Petko; Heine, Thomas; Röschenthaler, Gerd-Volker; Eicher, Johannes; Vankova, Nina

    2015-04-28

    We investigate computationally a series of intramolecular frustrated Lewis pairs (FLPs), with the general formula Mes2PCHRCH2B(C6F5)2, that are known from the literature to either activate molecular hydrogen (FLPs with R = H (1) or Me (4)), or remain inert (FLPs with R = Ph (2) or SiMe3 (3)). The prototypical system Mes2PCH2CH2B(C6F5)2 (1) has been described in the literature (Grimme et al., Angew. Chem., Int. Ed., 2010; Rokob et al., J. Am. Chem. Soc., 2013) as an intramolecular reactant that triggers the reaction with H2 in a bimolecular concerted fashion. In the current study, we show that the concept of intramolecular H2 activation by linked FLPs is not able to explain the inertness of the derivative compounds 2 and 3 towards H2. To cope with this, we propose an alternative intermolecular mechanism for the investigated reaction, assuming stacking of two open-chain FLP conformers, and formation of a dimeric reactant with two Lewis acid–base domains, that can split up to two hydrogen molecules. Using quantum-chemical methods, we compute the reaction profiles describing these alternative mechanisms, and compare the derived predictions with earlier reported experimental results. We show that only the concept of intermolecular H2 activation could explain both the activity of the FLPs having small substituents in the bridging molecular region, and the inertness of the FLPs with a bulkier substitution, in a consistent way. Importantly, the intermolecular H2 activation driven by intramolecular FLPs indicates the key role of steric factors and noncovalent interactions for the design of metal-free systems that can efficiently split H2, and possibly serve as metal-free hydrogenation catalysts. PMID:25812167

  11. THz Communications using Photonics and Electronic Devices: the Race to Data-Rate

    NASA Astrophysics Data System (ADS)

    Ducournau, Guillaume; Szriftgiser, Pascal; Pavanello, Fabio; Peytavit, Emilien; Zaknoune, Mohammed; Bacquet, Denis; Beck, Alexandre; Akalin, Tahsin; Lampin, Jean-François; Lampin, Jean-François

    2015-02-01

    With the mass development of mobile data transfers, wireless communications have recently entered a new area: the carrier frequency is now entering the THz region. After a brief overview of context and key features of THz communication, focus is given on photonic-based THz emitters based on quasi-optic UTC-PDs. A special design of wideband photomixer is presented and its applications for narrow bandwidth THz generation. Using this photomixer, communication links at 200, 400 and 600 GHz are presented.

  12. Intramolecular photo-physical processes and spectral-luminescence properties of a dye merocyanine 540 and its complexes with water

    NASA Astrophysics Data System (ADS)

    Bazyl', O. K.; Svetlichnyi, V. A.

    2015-12-01

    Merocyanine 540 (M540) is famous dye that used in electronics and medicine. An important feature of the dye is a significant intramolecular transfer of the electron density in the excited state. Experimentally was investigated the electronic absorption and fluorescence spectra in different solvents M540. Electronic structure, spectra and rate constants of photo-physical processes of an isolated molecule and its complexes with water molecules were calculated by INDO method with spectroscopic parameterization. Analysis of the results allowed establishing the effect of individual fragments and hydrogen bonds with water on the electronic charge transfer between the terminal units in the state S1. Examination of photo-physical processes of decomposition of the fluorescent state was showed that the intramolecular processes of decay of the S1 state are not the cause of the differences calculated and experimental fluorescence quantum yield. Consideration of trans-cis photoisomerization leads to the elimination of this non-compliance.

  13. Direct electrical communication between chemically modified enzymes and metal electrodes. 1. Electron transfer from glucose oxidase to metal electrodes via electron relays, bound covalently to the enzyme

    SciTech Connect

    Degani, Y.; Heller, A.

    1987-03-12

    Glucose-reduced glucose oxidase does not directly transfer electrons to conventional electrodes because the distance between its redox centers and the electrode surface exceeds, even on closest approach, the distance across which electrons are transferred at sufficient rates. Therefore, electrical communication between the redox centers of this enzyme and electrodes required either the presence, and diffusion to and from the enzyme's redox center, of O/sub 2/ and H/sub 2/O/sub 2/, or the presence of members of a redox couple, or the use of special electrodes like TTF/TCNQ. They show here that direct electrical communication between the redox center of a large enzyme molecule and a simple metal electrode can be established through chemical modification of the enzyme. When a sufficient number of electron-relaying centers are attached through covalent bonding to the protein of glucose oxidase, electrons are transferred from the enzyme's redox centers to relays that are closer to the periphery of the enzyme. Because some of the relays are located sufficiently close to the enzyme's surface, electrons are transferred at practical rates to the electrode. As a result, a glucose-concentration-dependent current flows in an electrochemical cell made with conventional electrodes when the electrolytic solution contains the relay-modified enzyme. Such a current does not flow when the solution contains the natural enzyme. Specifically, electrical communication is established between the FAD/FADH/sub 2/ centers of glucose oxidase and gold, platinum, or carbon electrodes through the covalent bonding of an average of 12 molecules of ferrocenecarboxylic acid per glucose oxidase molecule.

  14. E-Mail Bonding: Making the Most of Electronic Communication between Teacher and Student.

    ERIC Educational Resources Information Center

    Zolten, Jerry

    An instructor's idea of using required e-mail as a communication link with students in the basic public speaking course sprang from his work with Gerald M. Philips in the pioneering reticence program he developed at Penn State University in the 1970s and 1980s. The instructor's focus in teaching a basic communication course has always been more on…

  15. 76 FR 45860 - In the Matter of Certain Electronic Devices, Including Wireless Communication Devices, Portable...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-01

    ... Music and Data Processing Devices, and Tablet Computers; Notice of Institution of Investigation... communication devices, portable music and data processing devices, and tablet computers by reason of... communication devices, portable music and data processing devices, and tablet computers that infringe one...

  16. The Function of Electronic Communication Devices in Assisting Parental Involvement in Middle Schools

    ERIC Educational Resources Information Center

    Koch, Cotton S.

    2010-01-01

    The importance of home-to-school and school-to-home communication and parental involvement is well documented by researchers and acknowledged by practitioners. A number of earlier studies argue that there is a positive association between two-way communication, parental involvement, and student achievement at all levels of K-12 education. However,…

  17. Self-Care Communication during Medical Encounters: Implications for Future Electronic Medical Records

    PubMed Central

    Arar, Nedal H; Wang, Chen-Pin; Pugh, Jacqueline A

    2006-01-01

    Objective The growing importance of electronic medical records (EMRs) to healthcare systems is evident, yet the debate concerning their impact on patient-provider communication during encounters remains unresolved. For this study, we hypothesize that providers' use of the EMR will improve patientprovider communication concerning self-care during the medical encounter. Design Cross-sectional, observational study. Setting A primary-care outpatient clinic of the South Texas Veterans Health Care System in San Antonio, TX, USA. Methods A convenience sample of 50 patient/physician encounters was videotaped, transcribed verbatim, and analyzed to determine the time that the physician spent using the EMR and self-care topics discussed. Self-care topics included medication use, recognition of disease symptoms, diet, exercise, management of physical and emotional distress, self-monitoring activities, cigarette smoking, alcohol consumption, and family support/community resources. Two observers independently coded for the kind of self-care topics (kappa = 0.91) using the Atlas.ti software package. Results Encounters averaged 22.6 minutes (range: 5–47, SD = 8.9). We identified two encounter types based on EMR usage: low use (n = 13), with EMR use of two minutes or less, and moderate to high EMR use (n = 37), with EMR use of five minutes or more. Average time for encounters was 25 minutes for moderate to high EMR use encounters and 16 minutes for low EMR use encounters (t test, p < 0.001). Issues pertaining to facets of self-care management were discussed in every physician-patient interaction (100 percent). The most frequently discussed self-care topics were medication use (100 percent), physical distress (76 percent), and disease symptoms (76 percent). Self-monitoring activities, exercise, and diet were discussed in 62 percent, 60 percent, and 46 percent of the 50 encounters respectively. Emotional distress (26 percent), smoking (30 percent), family support

  18. Copper-catalyzed intramolecular cyclization of N-propargyl-adenine: synthesis of purine-fused tricyclics.

    PubMed

    Li, Ren-Long; Liang, Lei; Xie, Ming-Sheng; Qu, Gui-Rong; Niu, Hong-Ying; Guo, Hai-Ming

    2014-04-18

    A novel protocol to construct fluorescent purine-fused tricyclic products via intramolecular cyclization of N-propargyl-adenine has been developed. With CuBr as the catalyst, a series of purine-fused tricyclic products were obtained in good to excellent yields (19 examples, 75-89% yields). When R2 was a hydrogen atom in N-propargyl-adenines, the reactions only afforded the endocyclic double bond products. When R2 was an aryl group, the electron-donating groups favored the endocyclic double bond products, while the electron-withdrawing groups favored the exocyclic double bond products. PMID:24678722

  19. Electronic teaching files: seven-year experience using a commercial picture archiving and communication system.

    PubMed

    Siegel, E; Reiner, B

    2001-06-01

    With the advent of electronic imaging and the internet, the ability to create, search, access, and archive digital imaging teaching files has dramatically improved. Despite the fact that a picture archival and communication system (PACS) has the potential to greatly simplify the creation of, archival, and access to a department or multifacility teaching file, this potential has not yet been satisfactorily realized in our own and most other PACS installations. Several limitations of the teaching file tools within our PACS have become apparent over time. These have, at our facility, resulted in a substantially reduced role of the teaching file tools for conferences, daily teaching, and research purposes. With the PACS at our institution, academic folders can only be created by the systems engineer, which often serves as an impediment to the teaching process. Once these folders are created, multiple steps are required to identify the appropriate folders, and subsequently save images. Difficulties exist for those attempting to search for the teaching file images. Without pre-existing knowledge of the folder name and contents, it is difficult to query the system for specific images. This is due to the fact that there is currently no fully satisfactory mechanism for categorizing, indexing, and searching cases using the PACS. There is currently no easy mechanism to save teaching, research, or clinical files onto a CD or other removable media or to automatically strip demographic or other patient information from the images. PACS vendors should provide much more sophisticated tools to create and annotate teaching file images in an easy to use but standard format (possibly Radiological Society of North America's Medical Image Resource Center [MIRC] format) that could be exchanged with other sites and other vendors' PAC systems. The privilege to create teaching or conference files should be given to the individual radiologists, technologists, and other users, and an audit

  20. Self-contained miniature electronics transceiver provides voice communication in hazardous environment

    NASA Technical Reports Server (NTRS)

    Cribb, H. E.

    1970-01-01

    Two-way wireless voice communications system is automatic, provides freedom of movement, allows for complete awareness of the environment, and does not present any additional hazards such as activation of electromagnetic sensitive devices.

  1. David Meets Goliath on the Information Superhighway: Venezuela in the Context of the Electronic Communication Networks.

    ERIC Educational Resources Information Center

    Sanchez-Vegas, Saadia

    1995-01-01

    Discusses Venezuela's information and communications technology infrastructure and usage patterns; examines future networking plans; and addresses political and economic considerations linked to the information and technology problems in Venezuela and in Latin America in general. (LRW)

  2. Electronic mail communication between physicians and patients: a review of challenges and opportunities.

    PubMed

    Antoun, Jumana

    2016-04-01

    Although promising benefits hold for email communication between physicians and patients in terms of lowering the costs of health care while maintaining or improving the quality of disease management and health promotion, physician use of email with patients is still low and lags behind the willingness of patients to communicate with their physicians through email. There is also a discrepancy between physicians' willingness and actual practice of email communication. Several factors may explain these discrepancies. They include physicians differ in their experience and attitude towards information technology; some may not be convinced that patients appreciate, need and can communicate by email with their doctors; others are still waiting for robust evidence on service performance and efficiency in addition to patient satisfaction and outcome that support such practice; and many are reluctant to do so because of perceived barriers. This report is a review of the literature on the readiness for and adoption of physician-patient email communication, and how can challenges be or have been addressed. The need for Governmental support and directives for email communication to move forward is iterated, and opportunities for future research are pointed out. PMID:26711957

  3. Intramolecular hydrogen bonds in sulfur-containing aminophenols

    NASA Astrophysics Data System (ADS)

    Belkov, M. V.; Harbachova, A. N.; Ksendzova, G. A.; Polozov, G. I.; Skornyakov, I. V.; Sorokin, V. L.; Tolstorozhev, G. B.; Shadyro, O. I.

    2010-07-01

    IR Fourier spectroscopy methods have been adopted to study intramolecular interactions that occur in CCl4 solutions of antiviral derivatives of aminophenol. Analysis of the IR spectra showed that intramolecular bonds O-H···N, O-H···O=C, N-H···O=S=O, and O-H···O=S=O can occur in these compounds depending on the substituent on the amino group. Not only the presence of intramolecular O-H···N, O-H···O=S=O, and N- H···O=S=O hydrogen bonds in 2-amino-4,6-di-tert-butylphenol derivatives containing a sulfonamide fragment but also conformational equilibrium among these types of intramolecular interactions are essential for the manifestation of high efficiency in suppressing HIV-infection in cell culture.

  4. Synchronous intramolecular cycloadditions of the polyene macrolactam polyketide heronamide C.

    PubMed

    Booth, Thomas J; Alt, Silke; Capon, Robert J; Wilkinson, Barrie

    2016-05-11

    A growing number of natural products appear to arise from biosynthetic pathways that involve pericyclic reactions. We show here that for the heronamides this can occur via two spontaneous pathways involving alternative thermal or photochemical intramolecular cycloadditions. PMID:27091090

  5. Thermal selectivity of intermolecular versus intramolecular reactions on surfaces

    PubMed Central

    Cirera, Borja; Giménez-Agulló, Nelson; Björk, Jonas; Martínez-Peña, Francisco; Martin-Jimenez, Alberto; Rodriguez-Fernandez, Jonathan; Pizarro, Ana M.; Otero, Roberto; Gallego, José M.; Ballester, Pablo; Galan-Mascaros, José R.; Ecija, David

    2016-01-01

    On-surface synthesis is a promising strategy for engineering heteroatomic covalent nanoarchitectures with prospects in electronics, optoelectronics and photovoltaics. Here we report the thermal tunability of reaction pathways of a molecular precursor in order to select intramolecular versus intermolecular reactions, yielding monomeric or polymeric phthalocyanine derivatives, respectively. Deposition of tetra-aza-porphyrin species bearing ethyl termini on Au(111) held at room temperature results in a close-packed assembly. Upon annealing from room temperature to 275 °C, the molecular precursors undergo a series of covalent reactions via their ethyl termini, giving rise to phthalocyanine tapes. However, deposition of the tetra-aza-porphyrin derivatives on Au(111) held at 300 °C results in the formation and self-assembly of monomeric phthalocyanines. A systematic scanning tunnelling microscopy study of reaction intermediates, combined with density functional calculations, suggests a [2+2] cycloaddition as responsible for the initial linkage between molecular precursors, whereas the monomeric reaction is rationalized as an electrocyclic ring closure. PMID:26964764

  6. Thermal selectivity of intermolecular versus intramolecular reactions on surfaces

    NASA Astrophysics Data System (ADS)

    Cirera, Borja; Giménez-Agulló, Nelson; Björk, Jonas; Martínez-Peña, Francisco; Martin-Jimenez, Alberto; Rodriguez-Fernandez, Jonathan; Pizarro, Ana M.; Otero, Roberto; Gallego, José M.; Ballester, Pablo; Galan-Mascaros, José R.; Ecija, David

    2016-03-01

    On-surface synthesis is a promising strategy for engineering heteroatomic covalent nanoarchitectures with prospects in electronics, optoelectronics and photovoltaics. Here we report the thermal tunability of reaction pathways of a molecular precursor in order to select intramolecular versus intermolecular reactions, yielding monomeric or polymeric phthalocyanine derivatives, respectively. Deposition of tetra-aza-porphyrin species bearing ethyl termini on Au(111) held at room temperature results in a close-packed assembly. Upon annealing from room temperature to 275 °C, the molecular precursors undergo a series of covalent reactions via their ethyl termini, giving rise to phthalocyanine tapes. However, deposition of the tetra-aza-porphyrin derivatives on Au(111) held at 300 °C results in the formation and self-assembly of monomeric phthalocyanines. A systematic scanning tunnelling microscopy study of reaction intermediates, combined with density functional calculations, suggests a [2+2] cycloaddition as responsible for the initial linkage between molecular precursors, whereas the monomeric reaction is rationalized as an electrocyclic ring closure.

  7. Thermal selectivity of intermolecular versus intramolecular reactions on surfaces.

    PubMed

    Cirera, Borja; Giménez-Agulló, Nelson; Björk, Jonas; Martínez-Peña, Francisco; Martin-Jimenez, Alberto; Rodriguez-Fernandez, Jonathan; Pizarro, Ana M; Otero, Roberto; Gallego, José M; Ballester, Pablo; Galan-Mascaros, José R; Ecija, David

    2016-01-01

    On-surface synthesis is a promising strategy for engineering heteroatomic covalent nanoarchitectures with prospects in electronics, optoelectronics and photovoltaics. Here we report the thermal tunability of reaction pathways of a molecular precursor in order to select intramolecular versus intermolecular reactions, yielding monomeric or polymeric phthalocyanine derivatives, respectively. Deposition of tetra-aza-porphyrin species bearing ethyl termini on Au(111) held at room temperature results in a close-packed assembly. Upon annealing from room temperature to 275 °C, the molecular precursors undergo a series of covalent reactions via their ethyl termini, giving rise to phthalocyanine tapes. However, deposition of the tetra-aza-porphyrin derivatives on Au(111) held at 300 °C results in the formation and self-assembly of monomeric phthalocyanines. A systematic scanning tunnelling microscopy study of reaction intermediates, combined with density functional calculations, suggests a [2+2] cycloaddition as responsible for the initial linkage between molecular precursors, whereas the monomeric reaction is rationalized as an electrocyclic ring closure. PMID:26964764

  8. Exciton Correlations in Intramolecular Singlet Fission.

    PubMed

    Sanders, Samuel N; Kumarasamy, Elango; Pun, Andrew B; Appavoo, Kannatassen; Steigerwald, Michael L; Campos, Luis M; Sfeir, Matthew Y

    2016-06-15

    We have synthesized a series of asymmetric pentacene-tetracene heterodimers with a variable-length conjugated bridge that undergo fast and efficient intramolecular singlet fission (iSF). These compounds have distinct singlet and triplet energies, which allow us to study the spatial dynamics of excitons during the iSF process, including the significant role of exciton correlations in promoting triplet pair generation and recombination. We demonstrate that the primary photoexcitations in conjugated dimers are delocalized singlets that enable fast and efficient iSF. However, in these asymmetric dimers, the singlet becomes more localized on the lower energy unit as the length of the bridge is increased, slowing down iSF relative to analogous symmetric dimers. We resolve the recombination kinetics of the inequivalent triplets produced via iSF, and find that they primarily decay via concerted processes. By identifying different decay channels, including delayed fluorescence via triplet-triplet annihilation, we can separate transient species corresponding to both correlated triplet pairs and uncorrelated triplets. Recombination of the triplet pair proceeds rapidly despite our experimental and theoretical demonstration that individual triplets are highly localized and unable to be transported across the conjugated linker. In this class of compounds, the rate of formation and yield of uncorrelated triplets increases with bridge length. Overall, these constrained, asymmetric systems provide a unique platform to isolate and study transient species essential for singlet fission, which are otherwise difficult to observe in symmetric dimers or condensed phases. PMID:27183040

  9. Femtochemistry of Intramolecular Charge and Proton Transfer Reactions in Solution

    SciTech Connect

    Douhal, Abderrazzak; Sanz, Mikel; Carranza, Maria Angeles; Organero, Juan Angel; Tormo, Laura

    2005-03-17

    We report on the first observation of ultrafast intramolecular charge- and proton-transfer reactions in 4'-dimethylaminoflavonol (DAMF) in solution. Upon femtosecond excitation of a non-planar structure of DMAF in apolar medium, the intramolecular charge transfer (ICT) does not occur, and a slow (2 ps) proton motion takes place. However, in polar solvents, the ICT is very fast (100-200 fs) and the produced structure is stabilized that proton motion takes place in few or tens of ps.

  10. Regulation of interleukin-4 signaling by extracellular reduction of intramolecular disulfides

    SciTech Connect

    Curbo, Sophie; Gaudin, Raphael; Carlsten, Mattias; Malmberg, Karl-Johan; Troye-Blomberg, Marita; Ahlborg, Niklas; Karlsson, Anna; Johansson, Magnus; Lundberg, Mathias

    2009-12-25

    Interleukin-4 (IL-4) contains three structurally important intramolecular disulfides that are required for the bioactivity of the cytokine. We show that the cell surface of HeLa cells and endotoxin-activated monocytes can reduce IL-4 intramolecular disulfides in the extracellular space and inhibit binding of IL-4 to the IL-4R{alpha} receptor. IL-4 disulfides were in vitro reduced by thioredoxin 1 (Trx1) and protein disulfide isomerase (PDI). Reduction of IL-4 disulfides by the cell surface of HeLa cells was inhibited by auranofin, an inhibitor of thioredoxin reductase that is an electron donor to both Trx1 and PDI. Both Trx1 and PDI have been shown to be located at the cell surface and our data suggests that these enzymes are involved in catalyzing reduction of IL-4 disulfides. The pro-drug N-acetylcysteine (NAC) that promotes T-helper type 1 responses was also shown to mediate the reduction of IL-4 disulfides. Our data provides evidence for a novel redox dependent pathway for regulation of cytokine activity by extracellular reduction of intramolecular disulfides at the cell surface by members of the thioredoxin enzyme family.