WorldWideScience

Sample records for direct semidirect mechanism

  1. Direct-semidirect (DSD) codes

    International Nuclear Information System (INIS)

    Cvelbar, F.

    1999-01-01

    Recent codes for direct-semidirect (DSD) model calculations in the form of answers to a detailed questionnaire are reviewed. These codes include those embodying the classical DSD approach covering only the transitions to the bound states (RAF, HIKARI, and those of the Bologna group), as well as the code CUPIDO++ that also treats transitions to unbound states. (author)

  2. Evolution of egoism on semi-directed and undirected Barabási-Albert networks

    Science.gov (United States)

    Lima, F. W. S.

    2015-05-01

    Through Monte Carlo simulations, we study the evolution of the four strategies: Ethnocentric, altruistic, egoistic and cosmopolitan in one community of individuals. Interactions and reproduction among computational agents are simulated on undirected and semi-directed Barabási-Albert (BA) networks. We study the Hammond-Axelrod (HA) model on undirected and semi-directed BA networks for the asexual reproduction case. With a small modification in the traditional HA model, our simulations showed that egoism wins, differently from other results found in the literature where ethnocentric strategy is common. Here, mechanisms such as reciprocity are absent.

  3. Semi-direct sums of Lie algebras and continuous integrable couplings

    International Nuclear Information System (INIS)

    Ma Wenxiu; Xu Xixiang; Zhang Yufeng

    2006-01-01

    A relation between semi-direct sums of Lie algebras and integrable couplings of continuous soliton equations is presented, and correspondingly, a feasible way to construct integrable couplings is furnished. A direct application to the AKNS spectral problem leads to a novel hierarchy of integrable couplings of the AKNS hierarchy of soliton equations. It is also indicated that the study of integrable couplings using semi-direct sums of Lie algebras is an important step towards complete classification of integrable systems

  4. A discrete variational identity on semi-direct sums of Lie algebras

    Energy Technology Data Exchange (ETDEWEB)

    M, Wenxiu [Department of Mathematics and Statistics, University of South Florida, Tampa, FL 33620-5700 (United States)

    2007-12-14

    The discrete variational identity under general bilinear forms on semi-direct sums of Lie algebras is established. The constant {gamma} involved in the variational identity is determined through the corresponding solution to the stationary discrete zero-curvature equation. An application of the resulting variational identity to a class of semi-direct sums of Lie algebras in the Volterra lattice case furnishes Hamiltonian structures for the associated integrable couplings of the Volterra lattice hierarchy.

  5. A discrete variational identity on semi-direct sums of Lie algebras

    International Nuclear Information System (INIS)

    M, Wenxiu

    2007-01-01

    The discrete variational identity under general bilinear forms on semi-direct sums of Lie algebras is established. The constant γ involved in the variational identity is determined through the corresponding solution to the stationary discrete zero-curvature equation. An application of the resulting variational identity to a class of semi-direct sums of Lie algebras in the Volterra lattice case furnishes Hamiltonian structures for the associated integrable couplings of the Volterra lattice hierarchy

  6. CO2 forcing induces semi-direct effects with consequences for climate feedback interpretations

    Science.gov (United States)

    Andrews, Timothy; Forster, Piers M.

    2008-02-01

    Climate forcing and feedbacks are diagnosed from seven slab-ocean GCMs for 2 × CO2 using a regression method. Results are compared to those using conventional methodologies to derive a semi-direct forcing due to tropospheric adjustment, analogous to the semi-direct effect of absorbing aerosols. All models show a cloud semi-direct effect, indicating a rapid cloud response to CO2; cloud typically decreases, enhancing the warming. Similarly there is evidence of semi-direct effects from water-vapour, lapse-rate, ice and snow. Previous estimates of climate feedbacks are unlikely to have taken these semi-direct effects into account and so misinterpret processes as feedbacks that depend only on the forcing, but not the global surface temperature. We show that the actual cloud feedback is smaller than what previous methods suggest and that a significant part of the cloud response and the large spread between previous model estimates of cloud feedback is due to the semi-direct forcing.

  7. Direct and semi-direct approaches to lepton mixing with a massless neutrino

    International Nuclear Information System (INIS)

    King, Stephen F.; Ludl, Patrick Otto

    2016-01-01

    We discuss the possibility of enforcing a massless Majorana neutrino in the direct and semi-direct approaches to lepton mixing, in which the PMNS matrix is partly predicted by subgroups of a discrete family symmetry, extending previous group searches up to order 1535. We find a phenomenologically viable scheme for the semi-direct approach based on Q(648) which contains Δ(27) and the quaternion group as subgroups. This leads to novel predictions for the first column of the PMNS matrix corresponding to a normal neutrino mass hierarchy with m_1=0, and sum rules for the mixing angles and phase which are characterised by the solar angle being on the low side θ_1_2∼31"∘ and the Dirac (oscillation) CP phase δ being either about ±45"∘ or ±π.

  8. Direct and semi-direct radiative forcing of smoke aerosols over clouds

    Directory of Open Access Journals (Sweden)

    E. M. Wilcox

    2012-01-01

    Full Text Available Observations from Earth observing satellites indicate that dark carbonaceous aerosols that absorb solar radiation are widespread in the tropics and subtropics. When these aerosols mix with clouds, there is generally a reduction of cloudiness owing to absorption of solar energy in the aerosol layer. Over the subtropical South Atlantic Ocean, where smoke from savannah burning in southern Africa resides above a persistent deck of marine stratocumulus clouds, radiative heating of the smoke layer leads to a thickening of the cloud layer. Here, satellite observations of the albedo of overcast scenes of 25 km2 size or larger are combined with additional satellite observations of clouds and aerosols to estimate the top-of-atmosphere direct radiative forcing attributable to presence of dark aerosol above bright cloud, and the negative semi-direct forcing attributable to the thickening of the cloud layer. The average positive direct radiative forcing by smoke over an overcast scene is 9.2±6.6 W m−2 for cases with an unambiguous signal of absorbing aerosol over cloud in passive ultraviolet remote sensing observations. However, cloud liquid water path is enhanced by 16.3±7.7 g m−2 across the range of values for sea surface temperature for cases of smoke over cloud. The negative radiative forcing associated with this semi-direct effect of smoke over clouds is estimated to be −5.9±3.5 W m−2. Therefore, the cooling associated with the semi-direct cloud thickening effect compensates for greater than 60 % of the direct radiative effect. Accounting for the frequency of occurrence of significant absorbing aerosol above overcast scenes leads to an estimate of the average direct forcing of 1.0±0.7 W m−2 contributed by these scenes averaged over the subtropical southeast Atlantic Ocean during austral winter. The regional average of the negative semi-direct forcing is −0.7±0.4 W m−2

  9. The Rating of Direct and Semi-Direct Oral Proficiency Interviews: Comparing Performance at Lower Proficiency Levels.

    Science.gov (United States)

    Kenyon, Dorry M.; Tschirner, Erwin

    2000-01-01

    Reports on a study comparing student performances and test reliabilities for the German Speaking Test, a semi-direct tape-mediated oral proficiency test (GST) developed by the Center for Applied Linguistics, and the American Council on the Teaching of Foreign Languages Oral Proficiency Interviews. (Author/VWL)

  10. Abstract structure of partial function $*$-algebras over semi-direct product of locally compact groups

    Directory of Open Access Journals (Sweden)

    Arash Ghaani Farashahi

    2015-12-01

    Full Text Available This article presents a unified approach to the abstract notions of partial convolution and involution in $L^p$-function spaces over semi-direct product of locally compact groups. Let $H$ and $K$ be locally compact groups and $tau:Hto Aut(K$ be a continuous homomorphism.  Let $G_tau=Hltimes_tau K$ be the semi-direct product of $H$ and $K$ with respect to $tau$. We define left and right $tau$-convolution on $L^1(G_tau$ and we show that, with respect to each of them, the function space $L^1(G_tau$ is a Banach algebra. We define $tau$-convolution as a linear combination of the left and right $tau$-convolution and we show that the $tau$-convolution is commutative if and only if $K$ is abelian. We prove that there is a $tau$-involution on $L^1(G_tau$ such that with respect to the $tau$-involution and $tau$-convolution, $L^1(G_tau$ is a non-associative Banach $*$-algebra. It is also shown that when $K$ is abelian, the $tau$-involution and $tau$-convolution make $L^1(G_tau$ into a Jordan Banach $*$-algebra. Finally, we also present the generalized notation of $tau$-convolution for other $L^p$-spaces with $p>1$.

  11. Quantum algorithms for the hidden subgroup problem on some semi-direct product groups by reduction to Abelian cases

    International Nuclear Information System (INIS)

    Chi, Dong Pyo; Kim, Jeong San; Lee, Soojoon

    2006-01-01

    We consider the hidden subgroup problem on the semi-direct product of cyclic groups Z N -bar Z p , where p is a prime that does not divide p j -1 for any of the prime factors p j of N, and show that the hidden subgroup problem can be reduced to other ones for which solutions are already known

  12. Black carbon semi-direct effects on cloud cover: review and synthesis

    Directory of Open Access Journals (Sweden)

    D. Koch

    2010-08-01

    Full Text Available Absorbing aerosols (AAs such as black carbon (BC or dust absorb incoming solar radiation, perturb the temperature structure of the atmosphere, and influence cloud cover. Previous studies have described conditions under which AAs either increase or decrease cloud cover. The effect depends on several factors, including the altitude of the AA relative to the cloud and the cloud type. We attempt to categorize the effects into several likely regimes. Cloud cover is decreased if the AAs are embedded in the cloud layer. AAs below cloud may enhance convection and cloud cover. AAs above cloud top stabilize the underlying layer and tend to enhance stratocumulus clouds but may reduce cumulus clouds. AAs can also promote cloud cover in convergent regions as they enhance deep convection and low level convergence as it draws in moisture from ocean to land regions. Most global model studies indicate a regional variation in the cloud response but generally increased cloud cover over oceans and some land regions, with net increased low-level and/or reduced upper level cloud cover. The result is a net negative semi-direct effect feedback from the cloud response to AAs. In some of these climate model studies, the cooling effect of BC due to cloud changes is strong enough to essentially cancel the warming direct effects.

  13. Saving time and energy with oversubscription and semi-direct Møller-Plesset second order perturbation methods.

    Science.gov (United States)

    Fought, Ellie L; Sundriyal, Vaibhav; Sosonkina, Masha; Windus, Theresa L

    2017-04-30

    In this work, the effect of oversubscription is evaluated, via calling 2n, 3n, or 4n processes for n physical cores, on semi-direct MP2 energy and gradient calculations and RI-MP2 energy calculations with the cc-pVTZ basis using NWChem. Results indicate that on both Intel and AMD platforms, oversubscription reduces total time to solution on average for semi-direct MP2 energy calculations by 25-45% and reduces total energy consumed by the CPU and DRAM on average by 10-15% on the Intel platform. Semi-direct gradient time to solution is shortened on average by 8-15% and energy consumption is decreased by 5-10%. Linear regression analysis shows a strong correlation between time to solution and total energy consumed. Oversubscribing during RI-MP2 calculations results in performance degradations of 30-50% at the 4n level. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  14. Direct and semi-direct effects of aerosol climatologies on long-term climate simulations over Europe

    Science.gov (United States)

    Schultze, Markus; Rockel, Burkhardt

    2017-08-01

    This study compares the direct and semi-direct aerosol effects of different annual cycles of tropospheric aerosol loads for Europe from 1950 to 2009 using the regional climate model COSMO-CLM, which is laterally forced by reanalysis data and run using prescribed, climatological aerosol optical properties. These properties differ with respect to the analysis strategy and the time window, and are then used for the same multi-decadal period. Five simulations with different aerosol loads and one control simulation without any tropospheric aerosols are integrated and compared. Two common limitations of our simulation strategy, to fully assess direct and semi-direct aerosol effects, are the applied observed sea surface temperatures and sea ice conditions, and the lack of short-term variations in the aerosol load. Nevertheless, the impact of different aerosol climatologies on common regional climate model simulations can be assessed. The results of all aerosol-including simulations show a distinct reduction in solar irradiance at the surface compared with that in the control simulation. This reduction is strongest in the summer season and is balanced primarily by a weakening of turbulent heat fluxes and to a lesser extent by a decrease in longwave emissions. Consequently, the seasonal mean surface cooling is modest. The temperature profile responses are characterized by a shallow near-surface cooling and a dominant warming up to the mid-troposphere caused by aerosol absorption. The resulting stabilization of stratification leads to reduced cloud cover and less precipitation. A decrease in cloud water and ice content over Central Europe in summer possibly reinforce aerosol absorption and thus strengthen the vertical warming. The resulting radiative forcings are positive. The robustness of the results was demonstrated by performing a simulation with very strong aerosol forcing, which lead to qualitatively similar results. A distinct added value over the default aerosol

  15. Wigner functions for a class of semi-direct product groups

    International Nuclear Information System (INIS)

    Krasowska, Anna E; Ali, S Twareque

    2003-01-01

    Following a general method proposed earlier, we construct here Wigner functions defined on coadjoint orbits of a class of semidirect product groups. The groups in question are such that their unitary duals consist purely of representations from the discrete series and each unitary irreducible representation is associated with a coadjoint orbit. The set of all coadjoint orbits (hence UIRs) is finite and their union is dense in the dual of the Lie algebra. The simple structure of the groups and the orbits enables us to compute the various quantities appearing in the definition of the Wigner function explicitly. A large number of examples, with potential use in image analysis, is worked out

  16. Direct and semi-direct aerosol radiative effect on the Mediterranean climate variability using a coupled regional climate system model

    Science.gov (United States)

    Nabat, Pierre; Somot, Samuel; Mallet, Marc; Sevault, Florence; Chiacchio, Marc; Wild, Martin

    2015-02-01

    A fully coupled regional climate system model (CNRM-RCSM4) has been used over the Mediterranean region to investigate the direct and semi-direct effects of aerosols, but also their role in the radiation-atmosphere-ocean interactions through multi-annual ensemble simulations (2003-2009) with and without aerosols and ocean-atmosphere coupling. Aerosols have been taken into account in CNRM-RCSM4 through realistic interannual monthly AOD climatologies. An evaluation of the model has been achieved, against various observations for meteorological parameters, and has shown the ability of CNRM-RCSM4 to reproduce the main patterns of the Mediterranean climate despite some biases in sea surface temperature (SST), radiation and cloud cover. The results concerning the aerosol radiative effects show a negative surface forcing on average because of the absorption and scattering of the incident radiation. The SW surface direct effect is on average -20.9 Wm-2 over the Mediterranean Sea, -14.7 Wm-2 over Europe and -19.7 Wm-2 over northern Africa. The LW surface direct effect is weaker as only dust aerosols contribute (+4.8 Wm-2 over northern Africa). This direct effect is partly counterbalanced by a positive semi-direct radiative effect over the Mediterranean Sea (+5.7 Wm-2 on average) and Europe (+5.0 Wm-2) due to changes in cloud cover and atmospheric circulation. The total aerosol effect is consequently negative at the surface and responsible for a decrease in land (on average -0.4 °C over Europe, and -0.5 °C over northern Africa) and sea surface temperature (on average -0.5 °C for the Mediterranean SST). In addition, the latent heat loss is shown to be weaker (-11.0 Wm-2) in the presence of aerosols, resulting in a decrease in specific humidity in the lower troposphere, and a reduction in cloud cover and precipitation. Simulations also indicate that dust aerosols warm the troposphere by absorbing solar radiation, and prevent radiation from reaching the surface, thus

  17. Three semi-direct sum Lie algebras and three discrete integrable couplings associated with the modified K dV lattice equation

    International Nuclear Information System (INIS)

    Yu Zhang; Zhang Yufeng

    2009-01-01

    Three semi-direct sum Lie algebras are constructed, which is an efficient and new way to obtain discrete integrable couplings. As its applications, three discrete integrable couplings associated with the modified K dV lattice equation are worked out. The approach can be used to produce other discrete integrable couplings of the discrete hierarchies of soliton equations.

  18. Analysis of the /sup 27/Al(p,. gamma. )/sup 28/Si reaction at subbarrier energies in terms of the direct-semidirect model

    Energy Technology Data Exchange (ETDEWEB)

    Kicinska-Habior, M; Decowski, P; Dabrowska, M; Grochulski, W; Jaracz, P; Matulewicz, T; Sikora, B; Toke, J; Somorjai, E

    1983-06-01

    Differential cross sections for ..gamma..-transitions to 12 states in /sup 28/Si following nonresonant proton capture in /sup 27/Al nuclei (Esub(p)=1.625 keV) were measured and analysed in terms of the direct-semidirect model. The experimental data ar reproduced only when the complex coupling constant with the GDR is enhanced for the f partial wave in the entrance channel.

  19. Direct and semi-direct impacts of absorbing biomass burning aerosol on the climate of southern Africa: a Geophysical Fluid Dynamics Laboratory GCM sensitivity study

    Directory of Open Access Journals (Sweden)

    C. A. Randles

    2010-10-01

    Full Text Available Tropospheric aerosols emitted from biomass burning reduce solar radiation at the surface and locally heat the atmosphere. Equilibrium simulations using an atmospheric general circulation model (GFDL AGCM indicate that strong atmospheric absorption from these particles can cool the surface and increase upward motion and low-level convergence over southern Africa during the dry season. These changes increase sea level pressure over land in the biomass burning region and spin-up the hydrologic cycle by increasing clouds, atmospheric water vapor, and, to a lesser extent, precipitation. Cloud increases serve to reinforce the surface radiative cooling tendency of the aerosol. Conversely, if the climate over southern Africa were hypothetically forced by high loadings of scattering aerosol, then the change in the low-level circulation and increased subsidence would serve to decrease clouds, precipitation, and atmospheric water vapor. Surface cooling associated with scattering-only aerosols is mitigated by warming from cloud decreases. The direct and semi-direct climate impacts of biomass burning aerosol over southern Africa are sensitive to the total amount of aerosol absorption and how clouds change in response to the aerosol-induced heating of the atmosphere.

  20. Novel Semi-Direct OH Reactivity (kOH) Measurements by Chemical Ionization Mass Spectrometry during a Chamber Instrument Comparison Campaign and Continuous Ambient Air Sampling at a Central European GAW Station

    Science.gov (United States)

    Muller, J.; Kubistin, D.; Elste, T.; Plass-Duelmer, C.; Claude, A.; Englert, J.; Holla, R.; Fuchs, H.; Hofzumahaus, A.; Holland, F.; Novelli, A.; Tillmann, R.; Wegener, R.; Rohrer, F.; Yu, Z.; Bohn, B.; Williams, J.; Pfannerstill, E.; Edtbauer, A.; Kluepfel, T.

    2016-12-01

    Total OH reactivity (kOH) has been recognized as a useful measure to gauge the potential atmospheric oxidation capacity and a few different in-situ measurement techniques have been developed over the last 15 years. Here results are presented from a novel semi-direct method developed by the German Weather Service (DWD) utilizing a chemical ionization mass spectrometer (CIMS). Recently in April 2016, the CIMS system participated in a half-blind kOH instrument comparison campaign at the Forschungszentrum Jülich (FZJ) SAPHIR chamber. Experiments provided controlled conditions with a range of different VOC mixtures and varying NOx levels, representing environments dominated by biogenic or urban emissions. Alongside CIMS, kOH was also measured by systems using the comparative reactivity method (CRM) and the pump-probe technique with OH detection. The intercomparison revealed a good performance of CIMS at lower OH reactivities (0-15 s-1), a range for which the instrumental set up was optimized. Limitations of the CIMS system consist of an upper limit for kOH detection and the need for applying a chemical correction function as a result of instrument-internal HOx recycling. Findings and instrument parameters obtained from the FZJ SAPHIR campaign and flow tube experiments are then applied to ambient air kOH measurements at the Meteorological Observatory Hohenpeissenberg (MOHp), Germany. The CIMS instrument is used there for long-term measurements of OH, H2SO4, ROx and kOH. Here, we show ambient air kOH measurements, interpreted in conjunction with volatile organic compounds (VOC) and inorganic trace gases also measured at the GAW station Hohenpeissenberg. These observations provide a unique dataset to investigate turnover rates and seasonal cycles of reactive trace gases, i.e. sources that make up total OH reactivity in this central European, rural setting.

  1. Strongly coupled semidirect mediation of supersymmetry breaking

    International Nuclear Information System (INIS)

    Ibe, M.; Izawa, K.-I.; Nakai, Y.

    2009-01-01

    Strongly coupled semidirect gauge mediation models of supersymmetry breaking through massive mediators with standard-model charges are investigated by means of composite degrees of freedom. Sizable mediation is realized to generate the standard-model gaugino masses for a small mediator mass without breaking the standard-model symmetries.

  2. Incretin secretion: direct mechanisms

    DEFF Research Database (Denmark)

    Balk-Møller, Emilie; Holst, Jens Juul; Kuhre, Rune Ehrenreich

    2014-01-01

    The incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are secreted from gastro-intestinal K- and L-cells, respectively, and play an important role in post-prandial blood glucose regulation. They do this by direct stimulation of the pancreatic β...... enzyme responsible for incretin degradation (dipeptidyl peptidase-4) is inhibited (drugs are already on the market) while the secretion of endogenous GLP-1 secretion is stimulated at the same time may prove particularly rewarding. In this section we review current knowledge on the mechanisms for direct...

  3. New directions in computational mechanics

    International Nuclear Information System (INIS)

    Hughes, T.J.R.

    1989-01-01

    A few areas of computation mechanics are identified in which considerable progress has occurred and continued extension and refinement are anticipated. In particular, some recent results are presented of calculations performed with general purpose large-scale nonlinear finite element programs. Recent progress in the development of finite element methods for fluids is described. Examples of adaptive refinement and ''SUPG'' type methods are presented. The ideas emanating from finite elements in fluids are now having some impact on solids and structures. Examples of new element technology for kinematically constrained media and space-time formulations in elastodynamics are presented. (orig.)

  4. Data systematics and semidirect decay probability of the giant dipole resonance

    International Nuclear Information System (INIS)

    Ishkhanov, B.S.; Kapitonov, I.M.; Tutyn', I.A.

    1998-01-01

    Information on probability of semidirect decay of giant dipole resonance of nuclei of sd- and fp-shells (A = 16-58) is elaborated on the base of the recent (γ, χγ ' ) experimental results. The shell effect in A-dependence of this probability is discovered

  5. A bistable mechanism for directional sensing

    International Nuclear Information System (INIS)

    Beta, C; Amselem, G; Bodenschatz, E

    2008-01-01

    We present a generic mechanism for directional sensing in eukaryotic cells that is based on bistable dynamics. As the key feature of this modeling approach, the velocity of trigger waves in the bistable sensing system changes its sign across cells that are exposed to an external chemoattractant gradient. This is achieved by combining a two-component activator/inhibitor system with a bistable switch that induces an identical symmetry breaking for arbitrary gradient input signals. A simple kinetic example is designed to illustrate the dynamics of a bistable directional sensing mechanism in numerical simulations

  6. The mechanism of directional coronary atherectomy

    NARCIS (Netherlands)

    V.A.W.M. Umans (Victor); E. Haine; J. Renkin; P.J. de Feyter (Pim); W. Wijns (William); P.W.J.C. Serruys (Patrick)

    1993-01-01

    textabstractAn attempt was made to assess the mechanism of directional coronary atherectomy using different methods of analysis. Quantitative coronary angiography was used as the gold standard to assess the immediate results of atherectomy, and a comparative quantitative analysis of atherectomy and

  7. Direct neutron capture and related mechanisms

    International Nuclear Information System (INIS)

    Lynn, J.E.; Raman, S.

    1990-01-01

    We consider the evidence for the role of direct and related mechanisms in neutron capture at low and medium energies. Firstly, we compare the experimental data on the thermal neutron cross sections for El transitions in light nuclei with careful estimates of direct capture. Over the full range of light nuclei with small cross sections direct capture is found to be the predominant mechanism, in some cases being remarkable accurate, but in a few showing evidence for collective effects. When resonance effects become substantial there is evidence for an important contribution from the closely related valence mechanism, but full agreement with the data in such cases appears to require the introduction of a more generalised valence model. The possibility of direct and valence mechanisms playing a role in M1 capture is studied, and it is concluded that in light nuclei at relatively low gamma ray energies, it does indeed play some role. In heavier nuclei it appears that the evidence, especially from the correlations between E1 and M1 transitions to the same final states, favours the hypothesis that the main transition strength is governed by the M1 giant resonance. 31 refs., 2 tabs

  8. New Directions in Mathematical Fluid Mechanics

    CERN Document Server

    Fursikov, Andrei V

    2010-01-01

    The scientific interests of Professor A.V. Kazhikhov were fundamentally devoted to Mathematical Fluid Mechanics, where he achieved outstanding results that had, and still have, a significant influence on this field. This volume, dedicated to the memory of A.V. Kazhikhov, presents the latest contributions from renowned world specialists in a number of new important directions of Mathematical Physics, mostly of Mathematical Fluid Mechanics, and, more generally, in the field of nonlinear partial differential equations. These results are mostly related to boundary value problems and to control problems for the Navier-Stokes equations, and for equations of heat convection. Other important topics include non-equilibrium processes, Poisson-Boltzmann equations, dynamics of elastic body, and related problems of function theory and nonlinear analysis.

  9. Double optomechanical transparency with direct mechanical interaction

    International Nuclear Information System (INIS)

    Li Ling-Chao; Shi Rao; Xu Jun; Hu Xiang-Ming

    2015-01-01

    We present a mechanism for double transparency in an optomechanical system. This mechanism is based on the coupling of a moving cavity mirror to a second mechanical oscillator. Due to the purely mechanical coupling and the radiation pressure, three pathways are established for excitations of the probe photons into the cavity photons. Destructive interference occurs at two different frequencies, leading to double transparency to the probe field. It is the coupling strength between the mechanical oscillators that determines the locations of the transparency windows. Moreover, the normal splitting appears for the generated Stokes field and the four-wave mixing process is inhibited on resonance. (paper)

  10. Directions for computational mechanics in automotive crashworthiness

    Science.gov (United States)

    Bennett, James A.; Khalil, T. B.

    1993-01-01

    The automotive industry has used computational methods for crashworthiness since the early 1970's. These methods have ranged from simple lumped parameter models to full finite element models. The emergence of the full finite element models in the mid 1980's has significantly altered the research direction. However, there remains a need for both simple, rapid modeling methods and complex detailed methods. Some directions for continuing research are discussed.

  11. RNA-directed DNA methylation: Mechanisms and functions

    KAUST Repository

    Mahfouz, Magdy M.

    2010-01-01

    Epigenetic RNA based gene silencing mechanisms play a major role in genome stability and control of gene expression. Transcriptional gene silencing via RNA-directed DNA methylation (RdDM) guides the epigenetic regulation of the genome in response

  12. The pick-up mechanism in composite particle emission processes

    International Nuclear Information System (INIS)

    Zhang Jingshang; Yan Shiwei; Wang Cuilan

    1992-01-01

    The pick-up mechanism has been included in the exciton model for the light composite particle emissions. Based on the cluster phase space integration method the formation probabilities of α,d,t, 3 He are obtained. The calculation results of (n,t) cross sections indicate that this theoretical method can reproduce the experimental data nicely. For triton emissions in pre-equilibrium reaction processes, the semi-direct reactions are the dominant terms which are just omitted in the previous model calculation

  13. Inclusions and mechanical behavior in the short transverse direction

    International Nuclear Information System (INIS)

    Aubert, H.; Bouleau, M.; Laniesse, J.; Lelong, C.; Pigoury, M.

    1977-01-01

    The variables liable to characterize the distribution of inclusions in plates, and the relationships between the mechanical properties and the fatigue behavior in, on the one hand, the short transverse direction, and, on the other hand, the inclusions are studied. A decoherence is shown between inclusions and matrix as the cause of the failure by lamellar tearing [fr

  14. Mechanisms and direction of allocation bias in randomised clinical trials

    DEFF Research Database (Denmark)

    Paludan-Müller, Asger; Teindl Laursen, David Ruben; Hróbjartsson, A.

    2016-01-01

    clinical trials. Methods: Two systematic reviews and a theoretical analysis. We conducted one systematic review of empirical studies of motives/methods for deciphering patient allocation sequences; and another review of methods publications commenting on allocation bias. We theoretically analysed...... the mechanisms of allocation bias and hypothesised which main factors predicts its direction. Results: Three empirical studies addressed motives/methods for deciphering allocation sequences. Main motives included ensuring best care for patients and ensuring best outcome for the trial. Main methods included...... various manipulations with randomisation envelopes. Out of 57 methods publications 11 (19 %) mentioned explicitly that allocation bias can go in either direction. We hypothesised that the direction of allocation bias is mainly decided by the interaction between the patient allocators’ motives...

  15. Toxicogenomics-based identification of mechanisms for direct immunotoxicity.

    Science.gov (United States)

    Shao, Jia; Katika, Madhumohan R; Schmeits, Peter C J; Hendriksen, Peter J M; van Loveren, Henk; Peijnenburg, Ad A C M; Volger, Oscar L

    2013-10-01

    Compounds with direct immunotoxic properties, including metals, mycotoxins, agricultural pesticides, and industrial chemicals, form potential human health risks due to exposure through food, drinking water, and the environment. Insights into the mechanisms of action are currently lacking for the majority of these direct immunotoxicants. Therefore, the present work aimed to gain insights into the molecular mechanisms underlying direct immunotoxicity. To this end, we assessed in vitro the effects of 31 test compounds on the transcriptome of the human Jurkat T-cell line. These compounds included direct immunotoxicants, immunosuppressive drugs with different mode of actions, and nonimmunotoxic control chemicals. Pathway analysis of the microarray data allowed us to identify canonical pathways and Gene Ontology processes that were transcriptionally regulated in common by immunotoxicants (1) with structural similarities, such as tributyltin chloride and tributyltin oxide that activated the retinoic acid/X receptor signaling pathway and (2) without structural similarities, such as As2O3, dibutyltin chloride, diazinon, MeHg, ochratoxin A (OTA), S9-treated OTA, S9-treated cyclophosphamide, and S9-treated benzo[a]pyrene, which activated unfolded protein response, and FTY720, lindane, and propanil, which activated the cholesterol biosynthesis pathway. In addition, processes uniquely affected by individual immunotoxicants were identified, such as the induction of Notch receptor signaling and the downregulation of acute-phase response genes by OTA. These findings were validated by quantitative real-time PCR analysis of genes involved in these processes. Our study indicated that diverse modes of action are involved in direct immunotoxicity and that a set of pathways or genes, rather than one single gene, can be used to screen compounds for direct immunotoxicity.

  16. The combinatorics computation for Casimir operators of the symplectic Lie algebra and the application for determining the center of the enveloping algebra of a semidirect product

    International Nuclear Information System (INIS)

    Le Van Hop.

    1989-12-01

    The combinatorics computation is used to describe the Casimir operators of the symplectic Lie Algebra. This result is applied for determining the Center of the enveloping Algebra of the semidirect Product of the Heisenberg Lie Algebra and the symplectic Lie Algebra. (author). 10 refs

  17. Semidirect product gauge group [SU(3)cxSU(2)L]xU(1)Y and quantization of hypercharge

    International Nuclear Information System (INIS)

    Hattori, Chuichiro; Matsunaga, Mamoru; Matsuoka, Takeo

    2011-01-01

    In the standard model the hypercharges of quarks and leptons are not determined by the gauge group SU(3) c xSU(2) L xU(1) Y alone. We show that, if we choose the semidirect product group [SU(3) c xSU(2) L ]xU(1) Y as its gauge group, the hyperchages are settled to be n/6 mod Z(n=0,1,3,4). In addition, the conditions for gauge-anomaly cancellation give strong constraints. As a result, the ratios of the hypercharges are uniquely determined and the gravitational anomaly is automatically canceled. The standard charge assignment to quarks and leptons can be properly reproduced. For exotic matter fields their hypercharges are also discussed.

  18. Directed networks' different link formation mechanisms causing degree distribution distinction

    Science.gov (United States)

    Behfar, Stefan Kambiz; Turkina, Ekaterina; Cohendet, Patrick; Burger-Helmchen, Thierry

    2016-11-01

    Within undirected networks, scientists have shown much interest in presenting power-law features. For instance, Barabási and Albert (1999) claimed that a common property of many large networks is that vertex connectivity follows scale-free power-law distribution, and in another study Barabási et al. (2002) showed power law evolution in the social network of scientific collaboration. At the same time, Jiang et al. (2011) discussed deviation from power-law distribution; others indicated that size effect (Bagrow et al., 2008), information filtering mechanism (Mossa et al., 2002), and birth and death process (Shi et al., 2005) could account for this deviation. Within directed networks, many authors have considered that outlinks follow a similar mechanism of creation as inlinks' (Faloutsos et al., 1999; Krapivsky et al., 2001; Tanimoto, 2009) with link creation rate being the linear function of node degree, resulting in a power-law shape for both indegree and outdegree distribution. Some other authors have made an assumption that directed networks, such as scientific collaboration or citation, behave as undirected, resulting in a power-law degree distribution accordingly (Barabási et al., 2002). At the same time, we claim (1) Outlinks feature different degree distributions than inlinks; where different link formation mechanisms cause the distribution distinctions, (2) in/outdegree distribution distinction holds for different levels of system decomposition; therefore this distribution distinction is a property of directed networks. First, we emphasize in/outlink formation mechanisms as causal factors for distinction between indegree and outdegree distributions (where this distinction has already been noticed in Barker et al. (2010) and Baxter et al. (2006)) within a sample network of OSS projects as well as Java software corpus as a network. Second, we analyze whether this distribution distinction holds for different levels of system decomposition: open

  19. Mechanical impedance of the human body in vertical direction.

    Science.gov (United States)

    Holmlund, P; Lundström, R; Lindberg, L

    2000-08-01

    The mechanical impedance of the human body in sitting posture and vertical direction was measured during different experimental conditions, such as vibration level (0.5-1.4 m/s2), frequency (2-100 Hz), body weight (57-92 kg), relaxed and erect upper body posture. The outcome shows that impedance increases with frequency up to a peak at about 5 Hz after which it decreases in a complex manner which includes two additional peaks. The frequency at which the first and second impedance peak occurs decreases with higher vibration level. Erect, compared with relaxed body posture resulted in higher impedance magnitudes and with peaks located at somewhat higher frequencies. Heavy persons show higher impedance magnitudes and peaks at lower frequencies.

  20. Fluid mechanics of directional solidification at reduced gravity

    Science.gov (United States)

    Chen, C. F.

    1992-01-01

    The primary objective of the proposed research is to provide additional groundbased support for the flight experiment 'Casting and Solidification Technology' (CAST). This experiment is to be performed in the International Microgravity Laboratory-1 (IML-1) scheduled to be flown on a space shuttle mission scheduled for 1992. In particular, we will provide data on the convective motion and freckle formation during directional solidification of NH4Cl from its aqueous solution at simulated parameter ranges equivalent to reducing the gravity from the sea-level value down to 0.1 g or lower. The secondary objectives of the proposed research are to examine the stability phenomena associated with the onset of freckles and the mechanisms for their subsequent growth and decline (to eventual demise of some) by state-of-the-art imaging techniques and to formulate mathematical models for the prediction of the observed phenomena.

  1. Mechanisms of Hepatitis C Viral Resistance to Direct Acting Antivirals.

    Science.gov (United States)

    Ahmed, Asma; Felmlee, Daniel J

    2015-12-18

    There has been a remarkable transformation in the treatment of chronic hepatitis C in recent years with the development of direct acting antiviral agents targeting virus encoded proteins important for viral replication including NS3/4A, NS5A and NS5B. These agents have shown high sustained viral response (SVR) rates of more than 90% in phase 2 and phase 3 clinical trials; however, this is slightly lower in real-life cohorts. Hepatitis C virus resistant variants are seen in most patients who do not achieve SVR due to selection and outgrowth of resistant hepatitis C virus variants within a given host. These resistance associated mutations depend on the class of direct-acting antiviral drugs used and also vary between hepatitis C virus genotypes and subtypes. The understanding of these mutations has a clear clinical implication in terms of choice and combination of drugs used. In this review, we describe mechanism of action of currently available drugs and summarize clinically relevant resistance data.

  2. Mechanisms of Hepatitis C Viral Resistance to Direct Acting Antivirals

    Directory of Open Access Journals (Sweden)

    Asma Ahmed

    2015-12-01

    Full Text Available There has been a remarkable transformation in the treatment of chronic hepatitis C in recent years with the development of direct acting antiviral agents targeting virus encoded proteins important for viral replication including NS3/4A, NS5A and NS5B. These agents have shown high sustained viral response (SVR rates of more than 90% in phase 2 and phase 3 clinical trials; however, this is slightly lower in real-life cohorts. Hepatitis C virus resistant variants are seen in most patients who do not achieve SVR due to selection and outgrowth of resistant hepatitis C virus variants within a given host. These resistance associated mutations depend on the class of direct-acting antiviral drugs used and also vary between hepatitis C virus genotypes and subtypes. The understanding of these mutations has a clear clinical implication in terms of choice and combination of drugs used. In this review, we describe mechanism of action of currently available drugs and summarize clinically relevant resistance data.

  3. Mechanisms and Effects of Transcranial Direct Current Stimulation

    Science.gov (United States)

    Giordano, James; Bikson, Marom; Kappenman, Emily S.; Clark, Vincent P.; Coslett, H. Branch; Hamblin, Michael R.; Hamilton, Roy; Jankord, Ryan; Kozumbo, Walter J.; McKinley, R. Andrew; Nitsche, Michael A.; Reilly, J. Patrick; Richardson, Jessica; Wurzman, Rachel

    2017-01-01

    The US Air Force Office of Scientific Research convened a meeting of researchers in the fields of neuroscience, psychology, engineering, and medicine to discuss most pressing issues facing ongoing research in the field of transcranial direct current stimulation (tDCS) and related techniques. In this study, we present opinions prepared by participants of the meeting, focusing on the most promising areas of research, immediate and future goals for the field, and the potential for hormesis theory to inform tDCS research. Scientific, medical, and ethical considerations support the ongoing testing of tDCS in healthy and clinical populations, provided best protocols are used to maximize safety. Notwithstanding the need for ongoing research, promising applications include enhancing vigilance/attention in healthy volunteers, which can accelerate training and support learning. Commonly, tDCS is used as an adjunct to training/rehabilitation tasks with the goal of leftward shift in the learning/treatment effect curves. Although trials are encouraging, elucidating the basic mechanisms of tDCS will accelerate validation and adoption. To this end, biomarkers (eg, clinical neuroimaging and findings from animal models) can support hypotheses linking neurobiological mechanisms and behavioral effects. Dosage can be optimized using computational models of current flow and understanding dose–response. Both biomarkers and dosimetry should guide individualized interventions with the goal of reducing variability. Insights from other applied energy domains, including ionizing radiation, transcranial magnetic stimulation, and low-level laser (light) therapy, can be prudently leveraged. PMID:28210202

  4. RNA-directed DNA methylation: Mechanisms and functions

    KAUST Repository

    Mahfouz, Magdy M.

    2010-07-01

    Epigenetic RNA based gene silencing mechanisms play a major role in genome stability and control of gene expression. Transcriptional gene silencing via RNA-directed DNA methylation (RdDM) guides the epigenetic regulation of the genome in response to disease states, growth, developmental and stress signals. RdDM machinery is composed of proteins that produce and modify 24-nt- long siRNAs, recruit the RdDM complex to genomic targets, methylate DNA and remodel chromatin. The final DNA methylation pattern is determined by either DNA methyltransferase alone or by the combined action of DNA methyltransferases and demethylases. The dynamic interaction between RdDM and demethylases may render the plant epigenome plastic to growth, developmental, and environmental cues. The epigenome plasticity may allow the plant genome to assume many epigenomes and to have the right epigenome at the right time in response to intracellular or extracellular stimuli. This review discusses recent advances in RdDM research and considers future perspectives.

  5. Cognitive Mechanisms Underlying Directional and Non-directional Spatial-Numerical Associations across the Lifespan

    Directory of Open Access Journals (Sweden)

    Manuel Ninaus

    2017-08-01

    Full Text Available There is accumulating evidence suggesting an association of numbers with physical space. However, the origin of such spatial-numerical associations (SNAs is still debated. In the present study we investigated the development of two SNAs in a cross-sectional study involving children, young and middle-aged adults as well as the elderly: (1 the SNARC (spatial-numerical association of response codes effect, reflecting a directional SNA; and (2 the numerical bisection bias in a line bisection task with numerical flankers. Results revealed a consistent SNARC effect in all age groups that continuously increased with age. In contrast, a numerical bisection bias was only observed for children and elderly participants, implying an U-shaped distribution of this bias across age groups. Additionally, individual SNARC effects and numerical bisection biases did not correlate significantly. We argue that the SNARC effect seems to be influenced by longer-lasting experiences of cultural constraints such as reading and writing direction and may thus reflect embodied representations. Contrarily, the numerical bisection bias may originate from insufficient inhibition of the semantic influence of irrelevant numerical flankers, which should be more pronounced in children and elderly people due to development and decline of cognitive control, respectively. As there is an ongoing debate on the origins of SNAs in general and the SNARC effect in particular, the present results are discussed in light of these differing accounts in an integrative approach. However, taken together, the present pattern of results suggests that different cognitive mechanisms underlie the SNARC effect and the numerical bisection bias.

  6. Bail in Mechanisms in the Bank Recovery and Resolution Directive

    NARCIS (Netherlands)

    Joosen, B.P.M.

    2014-01-01

    With the adoption of the Bank Recovery and Resolution Directive, Europe has completed one of the three important pillars of the Banking Union. This directive introduces the resolution tool of ‘bail in’ that aims at putting the burden of bank rescue operations with the private sector. Bail outs

  7. Mechanical Design of an Omni-Directional Sensor Mount

    National Research Council Canada - National Science Library

    Rosheim, Mark

    2002-01-01

    This effort has been directed to development and demonstration of a gimbal mount capable of 180 degree singularity- free pitch and yaw motion about a two-axis center, avoiding the common problem of gimbal lock...

  8. Design of Electrostatic Directional Dry Adhesives for Robotic Attachment Mechanisms

    Data.gov (United States)

    National Aeronautics and Space Administration — Attachment mechanisms that are effective over a wide range of material types and surface conditions can be used for a variety of applications including manipulator...

  9. Direct and indirect stabilisation mechanisms in multiple electron capture

    Energy Technology Data Exchange (ETDEWEB)

    Roncin, P. [Paris-11 Univ., 91 - Orsay (France). Lab. de Collisions Atomiques et Moleculaires; Barat, M. [Paris-11 Univ., 91 - Orsay (France). Lab. de Collisions Atomiques et Moleculaires; Gaboriaud, M.N. [Paris-11 Univ., 91 -Orsay (France). Lab. de Collisions Atomiques et Moleculaires; Szilagyi, Z.S. [Paris-11 Univ., 91 - Orsay (France). Lab. de Collisions Atomiques et Moleculaires; Kazansky, A.K. [Paris-11 Univ., 91 - Orsay (France). Lab. de Collisions Atomiques et Moleculaires

    1995-05-01

    During the last years both experimental and theoretical works have focused on the problem of the stabilisation of two excited electrons on the projectile. In this contribution we would like to give experimental examples of the two suggested mechanisms and their extension to multiple electron capture. Our data are discussed together with those obtained with other experimental techniques and with theoretical predictions. (orig./WL).

  10. Effort Flow Analysis: A Methodology for Directed Product Evolution Using Rigid Body and Compliant Mechanisms

    National Research Council Canada - National Science Library

    Greer, James

    2002-01-01

    This dissertation presents a systematic design methodology for directed product evolution that uses both rigid body and compliant mechanisms to facilitate component combination in the domain of mechanical products...

  11. Crystal Growth and Fluid Mechanics Problems in Directional Solidification

    Science.gov (United States)

    Tanveer, Saleh A.; Baker, Gregory R.; Foster, Michael R.

    2001-01-01

    Our work in directional solidification has been in the following areas: (1) Dynamics of dendrites including rigorous mathematical analysis of the resulting equations; (2) Examination of the near-structurally unstable features of the mathematically related Hele-Shaw dynamics; (3) Numerical studies of steady temperature distribution in a vertical Bridgman device; (4) Numerical study of transient effects in a vertical Bridgman device; (5) Asymptotic treatment of quasi-steady operation of a vertical Bridgman furnace for large Rayleigh numbers and small Biot number in 3D; and (6) Understanding of Mullins-Sererka transition in a Bridgman device with fluid dynamics is accounted for.

  12. Direct landfill disposal versus Mechanical Biological Treatment (MBT

    Directory of Open Access Journals (Sweden)

    Kulhawik Katarzyna

    2016-09-01

    Full Text Available After the implementation of a new waste management system, in which recycling is the most dominating process, landfill disposal still appears to be the most popular method of waste management in Poland, in which waste undergoes gradual decomposition and the influence of climate conditions, for example, air and atmospheric fallout, leads to the production of leachate and biogas emissions, which contribute to continual threats to the natural environment and humans. The above-mentioned threats can be limited by applying suitable techniques of waste treatment before its disposal. A technology that is oriented to these aims is a mechanical biological treatment (MBT before disposal.

  13. Direct numerical methods of mathematical modeling in mechanical structural design

    International Nuclear Information System (INIS)

    Sahili, Jihad; Verchery, Georges; Ghaddar, Ahmad; Zoaeter, Mohamed

    2002-01-01

    Full text.Structural design and numerical methods are generally interactive; requiring optimization procedures as the structure is analyzed. This analysis leads to define some mathematical terms, as the stiffness matrix, which are resulting from the modeling and then used in numerical techniques during the dimensioning procedure. These techniques and many others involve the calculation of the generalized inverse of the stiffness matrix, called also the 'compliance matrix'. The aim of this paper is to introduce first, some different existing mathematical procedures, used to calculate the compliance matrix from the stiffness matrix, then apply direct numerical methods to solve the obtained system with the lowest computational time, and to compare the obtained results. The results show a big difference of the computational time between the different procedures

  14. Statistical mechanics of directed models of polymers in the square lattice

    CERN Document Server

    Rensburg, J V

    2003-01-01

    Directed square lattice models of polymers and vesicles have received considerable attention in the recent mathematical and physical sciences literature. These are idealized geometric directed lattice models introduced to study phase behaviour in polymers, and include Dyck paths, partially directed paths, directed trees and directed vesicles models. Directed models are closely related to models studied in the combinatorics literature (and are often exactly solvable). They are also simplified versions of a number of statistical mechanics models, including the self-avoiding walk, lattice animals and lattice vesicles. The exchange of approaches and ideas between statistical mechanics and combinatorics have considerably advanced the description and understanding of directed lattice models, and this will be explored in this review. The combinatorial nature of directed lattice path models makes a study using generating function approaches most natural. In contrast, the statistical mechanics approach would introduce...

  15. Direct and semi-direct impacts of absorbing biomass burning aerosol on the climate of southern Africa: a Geophysical Fluid Dynamics Laboratory GCM sensitivity study

    OpenAIRE

    C. A. Randles; V. Ramaswamy

    2010-01-01

    Tropospheric aerosols emitted from biomass burning reduce solar radiation at the surface and locally heat the atmosphere. Equilibrium simulations using an atmospheric general circulation model (GFDL AGCM) indicate that strong atmospheric absorption from these particles can cool the surface and increase upward motion and low-level convergence over southern Africa during the dry season. These changes increase sea level pressure over land in the biomass burning region and spin-up the hydrologic ...

  16. An alternative method for the measurement of the mechanical impulse of a vertically directed blast

    CSIR Research Space (South Africa)

    Turner, GR

    2008-01-01

    Full Text Available An alternative method for the measurement of the total mechanical impulse of a vertically directed blast due to an explosive charge is presented. The method differs from apparatus that employ a vertically displaced mass (similar in principle...

  17. Pore direction in relation to anisotropy of mechanical strength in a cubic starch compact

    NARCIS (Netherlands)

    Wu, Yu San; van Vliet, Lucas J; Frijlink, Henderik W; Stokroos, Ietse; van der Voort Maarschalk, Kees

    The purpose of this research was to evaluate the relation between preferential direction of pores and mechanical strength of cubic starch compacts. The preferential pore direction was quantified in SEM images of cross sections of starch compacts using a previously described algorithm for

  18. A Direct Mechanism of Ultrafast Intramolecular Singlet Fission in Pentacene Dimers

    Science.gov (United States)

    2016-08-24

    Queisser limit of solar power conversion efficiency. In conventional materials, the mechanism of SF is an intermolecular process (xSF), which is mediated by...property for materials used in third-generation solar cells and photodetectors, among other optoelectronic devices.1−3 Unfortunately, techno- logical...mixing. Previous work investigating the mechanism of xSF unfavorably compared the direct coupling mechanism against superexchange mediated by high

  19. Revised Mechanism and Improved Efficiency of the QuikChange Site-Directed Mutagenesis Method.

    Science.gov (United States)

    Xia, Yongzhen; Xun, Luying

    2017-01-01

    Site-directed mutagenesis has been widely used for the substitution, addition or deletion of nucleotide residues in a defined DNA sequence. QuikChange™ site-directed mutagenesis and its related protocols have been widely used for this purpose because of convenience and efficiency. We have recently demonstrated that the mechanism of the QuikChange™ site-directed mutagenesis process is different from that being proposed. The new mechanism promotes the use of partially overlapping primers and commercial PCR enzymes for efficient PCR and mutagenesis.

  20. Direct methods of solution for problems in mechanics from invariance principles

    International Nuclear Information System (INIS)

    Rajan, M.

    1986-01-01

    Direct solutions to problems in mechanics are developed from variational statements derived from the principle of invariance of the action integral under a one-parameter family of infinitesimal transformations. Exact, direct solution procedures for linear systems are developed by a careful choice of the arbitrary functions used to generate the infinitesimal transformations. It is demonstrated that the well-known methods for the solution of differential equations can be directly adapted to the required variational statements. Examples in particle and continuum mechanics are presented

  1. Damping mechanisms of high-lying single-particle states in 91Nb

    International Nuclear Information System (INIS)

    Molen, H. K. T. van der; Berg, A. M. van den; Harakeh, M. N.; Hunyadi, M.; Kalantar-Nayestanaki, N.; Akimune, H.; Daito, I.; Fujimura, H.; Ihara, F.; Inomata, T.; Ishibashi, K.; Yoshida, H.; Yosoi, M.; Fujita, Y.; Fujiwara, M.; Jaenecke, J.; O'Donnell, T. W.; Laurent, H.; Lhenry, I.; Rodin, V. A.

    2007-01-01

    Decay by proton emission from high-lying states in 91 Nb, populated in the 90 Zr(α,t) reaction at E α =180 MeV, has been investigated. Decay to the ground state and semidirect decay to the low-lying (2 + ,5 - , and 3 - ) phonon states in 90 Zr were observed. It was found that these phonon states play an important role in the damping process of the single-particle states. An optical-model coupled-channel approach was used successfully to describe the direct and semidirect parts of the decay

  2. Mechanical instability destabilises the ankle joint directly in the ankle-sprain mechanism.

    Science.gov (United States)

    Gehring, Dominic; Faschian, Katrin; Lauber, Benedikt; Lohrer, Heinz; Nauck, Tanja; Gollhofer, Albert

    2014-03-01

    Despite massive research efforts, it remains unclear how mechanical ankle instability (MAI) and functional ankle instability (FAI) affect joint control in the situation of ankle sprain. Thus, the purpose of this study was to evaluate whether individuals with MAI have deficits in stabilising their ankle joint in a close-to-injury situation compared with those with FAI and healthy controls. Ankle-joint control was assessed by means of three-dimensional motion analysis and electromyography in participants with FAI and MAI (n=19), in participants with pure FAI (n=9) and in healthy controls (n=18). Close-to-injury situations were simulated during standing, walking and jumping by means of a custom-made tilt platform. Individuals with FAI and MAI displayed significantly greater maximum ankle inversion angles (+5°) and inversion velocities (+50°/s) in the walking and jumping conditions compared to those with pure FAI and controls. Furthermore, individuals in the FAI and MAI group showed a significantly decreased pre-activation of the peroneus longus muscle during jumping compared to those with FAI. No differences between groups were found for plantar flexion and internal rotation, or for muscle activities following tilting of the platform. The present study demonstrates that MAI is characterised by impairments of ankle-joint control in close-to-injury situations. This could make these individuals more prone to recurrent ankle sprains, and suggests the need for additional mechanical support such as braces or even surgery. In addition, the study highlights the fact that dynamic experimental test conditions in the acting participant are needed to further unravel the mystery of chronic ankle instability.

  3. Energy implications of mechanical and mechanical-biological treatment compared to direct waste-to-energy.

    Science.gov (United States)

    Cimpan, Ciprian; Wenzel, Henrik

    2013-07-01

    Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical-biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation). The systems achieved net primary energy savings in a range between 34 and 140 MJprimary/100 MJinput waste, in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3-9.5%, 1-18% and 1-8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat recovery, the biodrying MBS-based system achieved the highest savings, on the condition of SRF co-combustion. As a sensitivity scenario, alternative utilisation of SRF in cement kilns was modelled. It supported similar or higher net savings for all pre-treatment systems compared to mass combustion WtE, except when WtE CHP was possible in the first two background energy scenarios. Recovery of plastics for recycling before energy recovery increased net energy savings in most scenario variations, over those of full

  4. Evaluation of glass transition temperature and dynamic mechanical properties of autopolymerized hard direct denture reline resins.

    Science.gov (United States)

    Takase, Kazuma; Watanabe, Ikuya; Kurogi, Tadafumi; Murata, Hiroshi

    2015-01-01

    This study assessed methods for evaluation of glass transition temperature (Tg) of autopolymerized hard direct denture reline resins using dynamic mechanical analysis and differential scanning calorimetry in addition to the dynamic mechanical properties. The Tg values of 3 different reline resins were determined using a dynamic viscoelastometer and differential scanning calorimeter, and rheological parameters were also determined. Although all materials exhibited higher storage modulus and loss modulus values, and a lower loss tangent at 37˚C with a higher frequency, the frequency dependence was not large. Tg values obtained by dynamic mechanical analysis were higher than those by differential scanning calorimetry and higher frequency led to higher Tg, while more stable Tg values were also obtained by that method. These results suggest that dynamic mechanical analysis is more advantageous for characterization of autopolymerized hard direct denture reline resins than differential scanning calorimetry.

  5. Prickle isoforms control the direction of tissue polarity by microtubule independent and dependent mechanisms

    Directory of Open Access Journals (Sweden)

    Katherine A. Sharp

    2016-03-01

    Full Text Available Planar cell polarity signaling directs the polarization of cells within the plane of many epithelia. While these tissues exhibit asymmetric localization of a set of core module proteins, in Drosophila, more than one mechanism links the direction of core module polarization to the tissue axes. One signaling system establishes a polarity bias in the parallel, apical microtubules upon which vesicles containing core proteins traffic. Swapping expression of the differentially expressed Prickle isoforms, Prickle and Spiny-legs, reverses the direction of core module polarization. Studies in the proximal wing and the anterior abdomen indicated that this results from their differential control of microtubule polarity. Prickle and Spiny-legs also control the direction of polarization in the distal wing (D-wing and the posterior abdomen (P-abd. We report here that this occurs without affecting microtubule polarity in these tissues. The direction of polarity in the D-wing is therefore likely determined by a novel mechanism independent of microtubule polarity. In the P-abd, Prickle and Spiny-legs interpret at least two directional cues through a microtubule-polarity-independent mechanism.

  6. Statistical mechanics of directed models of polymers in the square lattice

    International Nuclear Information System (INIS)

    Rensburg, E J Janse van

    2003-01-01

    Directed square lattice models of polymers and vesicles have received considerable attention in the recent mathematical and physical sciences literature. These are idealized geometric directed lattice models introduced to study phase behaviour in polymers, and include Dyck paths, partially directed paths, directed trees and directed vesicles models. Directed models are closely related to models studied in the combinatorics literature (and are often exactly solvable). They are also simplified versions of a number of statistical mechanics models, including the self-avoiding walk, lattice animals and lattice vesicles. The exchange of approaches and ideas between statistical mechanics and combinatorics have considerably advanced the description and understanding of directed lattice models, and this will be explored in this review. The combinatorial nature of directed lattice path models makes a study using generating function approaches most natural. In contrast, the statistical mechanics approach would introduce partition functions and free energies, and then investigate these using the general framework of critical phenomena. Generating function and statistical mechanics approaches are closely related. For example, questions regarding the limiting free energy may be approached by considering the radius of convergence of a generating function, and the scaling properties of thermodynamic quantities are related to the asymptotic properties of the generating function. In this review the methods for obtaining generating functions and determining free energies in directed lattice path models of linear polymers is presented. These methods include decomposition methods leading to functional recursions, as well as the Temperley method (that is implemented by creating a combinatorial object, one slice at a time). A constant term formulation of the generating function will also be reviewed. The thermodynamic features and critical behaviour in models of directed paths may be

  7. Brain mechanisms associated with internally directed attention and self-generated thought.

    Science.gov (United States)

    Benedek, Mathias; Jauk, Emanuel; Beaty, Roger E; Fink, Andreas; Koschutnig, Karl; Neubauer, Aljoscha C

    2016-03-10

    Internal cognition like imagination and prospection require sustained internally directed attention and involve self-generated thought. This fMRI study aimed to disentangle the brain mechanisms associated with attention-specific and task-specific processes during internally directed cognition. The direction of attention was manipulated by either keeping a relevant stimulus visible throughout the task, or by masking it, so that the task had to be performed "in the mind's eye". The level of self-directed thought was additionally varied between a convergent and a divergent thinking task. Internally directed attention was associated with increased activation in the right anterior inferior parietal lobe (aIPL), bilateral lingual gyrus and the cuneus, as well as with extended deactivations of superior parietal and occipital regions representing parts of the dorsal attention network. The right aIPL further showed increased connectivity with occipital regions suggesting an active top-down mechanism for shielding ongoing internal processes from potentially distracting sensory stimulation in terms of perceptual decoupling. Activation of the default network was not related to internally directed attention per se, but rather to a higher level of self-generated thought. The findings hence shed further light on the roles of inferior and superior parietal cortex for internally directed cognition.

  8. Economic Evaluation of a Patient-Directed Music Intervention for ICU Patients Receiving Mechanical Ventilatory Support.

    Science.gov (United States)

    Chlan, Linda L; Heiderscheit, Annette; Skaar, Debra J; Neidecker, Marjorie V

    2018-05-04

    Music intervention has been shown to reduce anxiety and sedative exposure among mechanically ventilated patients. Whether music intervention reduces ICU costs is not known. The aim of this study was to examine ICU costs for patients receiving a patient-directed music intervention compared with patients who received usual ICU care. A cost-effectiveness analysis from the hospital perspective was conducted to determine if patient-directed music intervention was cost-effective in improving patient-reported anxiety. Cost savings were also evaluated. One-way and probabilistic sensitivity analyses determined the influence of input variation on the cost-effectiveness. Midwestern ICUs. Adult ICU patients from a parent clinical trial receiving mechanical ventilatory support. Patients receiving the experimental patient-directed music intervention received a MP3 player, noise-canceling headphones, and music tailored to individual preferences by a music therapist. The base case cost-effectiveness analysis estimated patient-directed music intervention reduced anxiety by 19 points on the Visual Analogue Scale-Anxiety with a reduction in cost of $2,322/patient compared with usual ICU care, resulting in patient-directed music dominance. The probabilistic cost-effectiveness analysis found that average patient-directed music intervention costs were $2,155 less than usual ICU care and projected that cost saving is achieved in 70% of 1,000 iterations. Based on break-even analyses, cost saving is achieved if the per-patient cost of patient-directed music intervention remains below $2,651, a value eight times the base case of $329. Patient-directed music intervention is cost-effective for reducing anxiety in mechanically ventilated ICU patients.

  9. Direct design of an energy landscape with bistable DNA origami mechanisms.

    Science.gov (United States)

    Zhou, Lifeng; Marras, Alexander E; Su, Hai-Jun; Castro, Carlos E

    2015-03-11

    Structural DNA nanotechnology provides a feasible technique for the design and fabrication of complex geometries even exhibiting controllable dynamic behavior. Recently we have demonstrated the possibility of implementing macroscopic engineering design approaches to construct DNA origami mechanisms (DOM) with programmable motion and tunable flexibility. Here, we implement the design of compliant DNA origami mechanisms to extend from prescribing motion to prescribing an energy landscape. Compliant mechanisms facilitate motion via deformation of components with tunable stiffness resulting in well-defined mechanical energy stored in the structure. We design, fabricate, and characterize a DNA origami nanostructure with an energy landscape defined by two stable states (local energy minima) separated by a designed energy barrier. This nanostructure is a four-bar bistable mechanism with two undeformed states. Traversing between those states requires deformation, and hence mechanical energy storage, in a compliant arm of the linkage. The energy barrier for switching between two states was obtained from the conformational distribution based on a Boltzmann probability function and closely follows a predictive mechanical model. Furthermore, we demonstrated the ability to actuate the mechanism into one stable state via additional DNA inputs and then release the actuation via DNA strand displacement. This controllable multistate system establishes a foundation for direct design of energy landscapes that regulate conformational dynamics similar to biomolecular complexes.

  10. Microstructure and mechanical behavior of direct metal laser sintered Inconel alloy 718

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Derek H. [Department of Mechanical Engineering, University of New Hampshire, Durham, NH 03824 (United States); Bicknell, Jonathan; Jorgensen, Luke [Turbocam Energy Solutions, Turbocam International, Dover, NH 03820 (United States); Patterson, Brian M.; Cordes, Nikolaus L. [Materials Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tsukrov, Igor [Department of Mechanical Engineering, University of New Hampshire, Durham, NH 03824 (United States); Knezevic, Marko, E-mail: marko.knezevic@unh.edu [Department of Mechanical Engineering, University of New Hampshire, Durham, NH 03824 (United States)

    2016-03-15

    In this paper, we investigate microstructure and quasi-static mechanical behavior of the direct metal laser sintered Inconel 718 superalloy as a function of build direction (BD). The printed material was further processed by annealing and double-aging, hot isostatic pressing (HIP), and machining. We characterize porosity fraction and distribution using micro X-ray computed tomography (μXCT), grain structure and crystallographic texture using electron backscattered diffraction (EBSD), and mechanical response in quasi-static tension and compression using standard mechanical testing at room temperature. Analysis of the μXCT imaging shows that majority of porosity develops in the outer layer of the printed material. However, porosity inside the material is also present. The EBSD measurements reveal formation of columnar grains, which favor < 001 > fiber texture components along the BD. These measurements also show evidence of coarse-grained microstructure present in the samples treated by HIP. Finally, analysis of grain boundaries reveal that HIP results in a large number of annealing twins compared to that in samples that underwent annealing and double-aging. The yield strength varies with the testing direction by approximately 7%, which is governed by a combination of grain morphology and crystallographic texture. In particular, we determine tension–compression asymmetry in the yield stress as well as anisotropy of the material flow during compression. We find that HIP lowers yield stress but improves ductility relative to the annealed and aged material. These results are discussed and critically compared with the data reported for wrought material in the same condition. - Highlights: • Microstructure and mechanical properties of DMLS Inconel 718 are studied in function of build direction. • Inhomogeneity of microstructure in the material in several conditions is quantified by μXCT and EBSD. • Anisotropy and asymmetry in the mechanical response are

  11. Microstructure and mechanical behavior of direct metal laser sintered Inconel alloy 718

    International Nuclear Information System (INIS)

    Smith, Derek H.; Bicknell, Jonathan; Jorgensen, Luke; Patterson, Brian M.; Cordes, Nikolaus L.; Tsukrov, Igor; Knezevic, Marko

    2016-01-01

    In this paper, we investigate microstructure and quasi-static mechanical behavior of the direct metal laser sintered Inconel 718 superalloy as a function of build direction (BD). The printed material was further processed by annealing and double-aging, hot isostatic pressing (HIP), and machining. We characterize porosity fraction and distribution using micro X-ray computed tomography (μXCT), grain structure and crystallographic texture using electron backscattered diffraction (EBSD), and mechanical response in quasi-static tension and compression using standard mechanical testing at room temperature. Analysis of the μXCT imaging shows that majority of porosity develops in the outer layer of the printed material. However, porosity inside the material is also present. The EBSD measurements reveal formation of columnar grains, which favor fiber texture components along the BD. These measurements also show evidence of coarse-grained microstructure present in the samples treated by HIP. Finally, analysis of grain boundaries reveal that HIP results in a large number of annealing twins compared to that in samples that underwent annealing and double-aging. The yield strength varies with the testing direction by approximately 7%, which is governed by a combination of grain morphology and crystallographic texture. In particular, we determine tension–compression asymmetry in the yield stress as well as anisotropy of the material flow during compression. We find that HIP lowers yield stress but improves ductility relative to the annealed and aged material. These results are discussed and critically compared with the data reported for wrought material in the same condition. - Highlights: • Microstructure and mechanical properties of DMLS Inconel 718 are studied in function of build direction. • Inhomogeneity of microstructure in the material in several conditions is quantified by μXCT and EBSD. • Anisotropy and asymmetry in the mechanical response are determined by

  12. Kinematics of Planetary Roller Screw Mechanism considering Helical Directions of Screw and Roller Threads

    Directory of Open Access Journals (Sweden)

    Shangjun Ma

    2015-01-01

    Full Text Available Based on the differential principle of thread transmission, an analytical model considering helical directions between screw and roller threads in planetary roller screw mechanism (PRSM is presented in this work. The model is critical for the design of PRSM with a smaller lead and a bigger pitch to realize a higher transmission accuracy. The kinematic principle of planetary transmission is employed to analyze the PRSM with different screw thread and roller thread directions. In order to investigate the differences with different screw thread and roller thread directions, the numerical model is developed by using the software Adams to validate the analytical solutions calculated by the presented model. The results indicate, when the helical direction of screw thread is identical with the direction of roller thread, that the lead of PRSM is unaffected regardless of whether sliding between screw and rollers occurs or not. Only when the direction of screw thread is reverse to the direction of roller thread, the design of PRSM with a smaller lead can be realized under a bigger pitch. The presented models and numerical simulation method can be used to research the transmission accuracy of PRSM.

  13. Predictive modeling capabilities from incident powder and laser to mechanical properties for laser directed energy deposition

    Science.gov (United States)

    Shin, Yung C.; Bailey, Neil; Katinas, Christopher; Tan, Wenda

    2018-01-01

    This paper presents an overview of vertically integrated comprehensive predictive modeling capabilities for directed energy deposition processes, which have been developed at Purdue University. The overall predictive models consist of vertically integrated several modules, including powder flow model, molten pool model, microstructure prediction model and residual stress model, which can be used for predicting mechanical properties of additively manufactured parts by directed energy deposition processes with blown powder as well as other additive manufacturing processes. Critical governing equations of each model and how various modules are connected are illustrated. Various illustrative results along with corresponding experimental validation results are presented to illustrate the capabilities and fidelity of the models. The good correlations with experimental results prove the integrated models can be used to design the metal additive manufacturing processes and predict the resultant microstructure and mechanical properties.

  14. Predictive modeling capabilities from incident powder and laser to mechanical properties for laser directed energy deposition

    Science.gov (United States)

    Shin, Yung C.; Bailey, Neil; Katinas, Christopher; Tan, Wenda

    2018-05-01

    This paper presents an overview of vertically integrated comprehensive predictive modeling capabilities for directed energy deposition processes, which have been developed at Purdue University. The overall predictive models consist of vertically integrated several modules, including powder flow model, molten pool model, microstructure prediction model and residual stress model, which can be used for predicting mechanical properties of additively manufactured parts by directed energy deposition processes with blown powder as well as other additive manufacturing processes. Critical governing equations of each model and how various modules are connected are illustrated. Various illustrative results along with corresponding experimental validation results are presented to illustrate the capabilities and fidelity of the models. The good correlations with experimental results prove the integrated models can be used to design the metal additive manufacturing processes and predict the resultant microstructure and mechanical properties.

  15. Syntrophic growth with direct interspecies electron transfer as the primary mechanism for energy exchange

    DEFF Research Database (Denmark)

    Shrestha, Pravin Malla; Rotaru, Amelia-Elena; Aklujkar, Muktak

    2013-01-01

    Direct interspecies electron transfer (DIET) through biological electrical connections is an alternative to interspecies H2 transfer as a mechanism for electron exchange in syntrophic cultures. However, it has not previously been determined whether electrons received via DIET yield energy...... dehydrogenase, the pilus-associated c-type cytochrome OmcS and pili consistent with electron transfer via DIET. These results suggest that electrons transferred via DIET can serve as the sole energy source to support anaerobic respiration....

  16. Microstructure of directionally solidified Ti-Fe eutectic alloy with low interstitial and high mechanical strength

    Science.gov (United States)

    Contieri, R. J.; Lopes, E. S. N.; Taquire de La Cruz, M.; Costa, A. M.; Afonso, C. R. M.; Caram, R.

    2011-10-01

    The performance of Ti alloys can be considerably enhanced by combining Ti and other elements, causing an eutectic transformation and thereby producing composites in situ from the liquid phase. This paper reports on the processing and characterization of a directionally solidified Ti-Fe eutectic alloy. Directional solidification at different growth rates was carried out in a setup that employs a water-cooled copper crucible combined with a voltaic electric arc moving through the sample. The results obtained show that a regular fiber-like eutectic structure was produced and the interphase spacing was found to be a function of the growth rate. Mechanical properties were measured using compression, microindentation and nanoindentation tests to determine the Vickers hardness, compressive strength and elastic modulus. Directionally solidified eutectic samples presented high values of compressive strength in the range of 1844-3000 MPa and ductility between 21.6 and 25.2%.

  17. Effect of excitation direction on cochlear macro-mechanics during bone conduction stimulation

    Science.gov (United States)

    Kamieniecki, Konrad; Tudruj, Sylwester; Piechna, Janusz; Borkowski, Paweł

    2018-05-01

    In many instances of hearing loss, audiological improvement can be made via direct excitation of a temporal bone (i.e., bone conduction). In order to design better and more efficient devices, the macro-mechanics of the bone conduction hearing pathway must be better understood. Based on previous empirical work, numerical models are useful. In this work, we present results of a time-domain Fluid Structure Interaction model that describes stimulation of the bone conduction pathway. The cochlea was modelled as uncoiled and consisted of an oval window, a round window, a basilar membrane and a helicotrema. In order to monitor pressure waves in the perilymph, the fluid was considered compressible. The excitation, in form of sinusoidal velocity, was applied to the cochlea bony walls. The system was excited in three perpendicular directions: along the basilar membrane, perpendicularly to the membrane and transversely to the membrane. The numerical simulation examined which stimulation direction maximally excited the basilar membrane, the pressure distributions for each excitation direction, and the associated mechanics.

  18. IN-DEPTH SEMI-DIRECTIVE INTERVIEW REGARDING THE METHODS, TECHNIQUES AND TOOLS USED BY BANKS TO ASSESS THE DEGREE OF CUSTOMERS’ SATISFACTION

    Directory of Open Access Journals (Sweden)

    BĂLTEANU CRISTINA

    2016-12-01

    Full Text Available The phenomenon of market globalization and also the periods of economic instability worldwide led to increased competition and hence to growing concerns of companies to continuously improve their products and services, the quality of which could be a real competitive advantage in attracting and retaining bigger segments of consumers. But to succeed in the market, the companies need to focus their efforts also to finding, knowing, understanding and meeting the needs, requirements and expectations of current and future consumers. Thus, it becomes essential that the flow of information be carried out in two ways: organization – customer, customer – organization, a particular importance being given to the frequency with which they get feedback from customers, this feedback determining the accuracy of the measures taken to improve those aspects appreciated by consumers as being nonconforming. Therefore, knowing the customer perception on the quality of offer has become vital, this being an important determinant of the degree of satisfaction which in turn can decisively influence the profitability of companies, regardless their field of activity. In this context, this paper, which is based on a qualitative marketing research, highlights the main categories of banking products and services used by Romanian consumers and their perceptions on banks and their offers. A particular attention was paid on the methods, techniques and tools used by banks to assess the satisfaction of their customers in order to improve their experience.

  19. Algebraic proofs for shallow water bi-Hamiltonian systems for three cocycle of the semi-direct product of Kac-Moody and Virasoro Lie algebras

    Czech Academy of Sciences Publication Activity Database

    Zuevsky, Alexander

    2018-01-01

    Roč. 16, č. 1 (2018), s. 1-8 ISSN 2391-5455 Institutional support: RVO:67985840 Keywords : Kac-Moody Lie algebras * cocycles Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.682, year: 2016 https://www.degruyter.com/view/j/math.2018.16.issue-1/math-2018-0002/math-2018-0002. xml

  20. Algebraic proofs for shallow water bi-Hamiltonian systems for three cocycle of the semi-direct product of Kac-Moody and Virasoro Lie algebras

    Czech Academy of Sciences Publication Activity Database

    Zuevsky, Alexander

    2018-01-01

    Roč. 16, č. 1 (2018), s. 1-8 ISSN 2391-5455 Institutional support: RVO:67985840 Keywords : Kac-Moody Lie algebras * cocycles Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.682, year: 2016 https://www.degruyter.com/view/j/math.2018.16.issue-1/math-2018-0002/math-2018-0002.xml

  1. Design options for cooperation mechanisms under the new European renewable energy directive

    International Nuclear Information System (INIS)

    Klessmann, Corinna; Lamers, Patrick; Ragwitz, Mario; Resch, Gustav

    2010-01-01

    In June 2009, a new EU directive on the promotion of renewable energy sources (RES) entered into effect. The directive 2009/28/EC, provides for three cooperation mechanisms that will allow member states to achieve their national RES target in cooperation with other member states: statistical transfer, joint projects, and joint support schemes. This article analyses the pros and cons of the three mechanisms and explores design options for their implementation through strategic and economic questions: How to counterbalance the major drawbacks of each mechanism? How to reflect a balance of costs and benefits between the involved member states? The analysis identifies a number of design options that respond to these questions, e.g. long term contracts to ensure sufficient flexibility for statistical transfers, a coordinated, standardised joint project approach to increase transparency in the European market, and a stepwise harmonisation of joint support schemes that is based on a cost-effective accounting approach. One conclusion is that the three cooperation mechanisms are closely interlinked. One can consider their relation to be a gradual transition from member state cooperation under fully closed national support systems in case of statistical transfers, to cooperation under fully open national support systems in a joint support scheme.

  2. Nucleation mechanism for the direct graphite-to-diamond phase transition

    Science.gov (United States)

    Khaliullin, Rustam Z.; Eshet, Hagai; Kühne, Thomas D.; Behler, Jörg; Parrinello, Michele

    2011-09-01

    Graphite and diamond have comparable free energies, yet forming diamond from graphite in the absence of a catalyst requires pressures that are significantly higher than those at equilibrium coexistence. At lower temperatures, the formation of the metastable hexagonal polymorph of diamond is favoured instead of the more stable cubic diamond. These phenomena cannot be explained by the concerted mechanism suggested in previous theoretical studies. Using an ab initio quality neural-network potential, we carried out a large-scale study of the graphite-to-diamond transition assuming that it occurs through nucleation. The nucleation mechanism accounts for the observed phenomenology and reveals its microscopic origins. We demonstrate that the large lattice distortions that accompany the formation of diamond nuclei inhibit the phase transition at low pressure, and direct it towards the hexagonal diamond phase at higher pressure. The proposed nucleation mechanism should improve our understanding of structural transformations in a wide range of carbon-based materials.

  3. EBSD characterization of the growth mechanism of SiC synthesized via direct microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jigang, E-mail: wangjigang@seu.edu.cn [Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Xizang Key Laboratory of Optical Information Processing and Visualization Technology, School of Information Engineering, Xizang Minzu University, Xianyang 712082 (China); Huang, Shan; Liu, Song; Qing, Zhou [Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

    2016-04-15

    Well-crystallized 3C-silicon carbide (SiC) grains/nanowires have been synthesized rapidly and conveniently via direct microwave heating, simply using silicon dioxide powders and artificial graphite as raw materials. The comprehensive characterizations have been employed to investigate the micro-structure of the obtained 3C-SiC products. Results indicated that, different from the classic screw dislocation growth mechanism, the 3C-SiC grains/nanowires synthesized via high-energy vacuum microwave irradiation were achieved through the two-dimension nucleation and laminar growth mechanism. Especially, the electron backscattered diffraction (EBSD) was employed to characterize the crystal planes of the as-grown SiC products. The calculated Euler angles suggested that the fastest-growing crystal planes (211) were overlapped gradually. Through the formation of the (421) transformation plane, (211) finally evolved to (220) which existed as the side face of SiC grains. The most stable crystal planes (111) became the regular hexagonal planes in the end, which could be explained by the Bravais rule. The characterization results of EBSD provided important experimental information for the evolution of crystal planes. - Graphical abstract: The formation of 3C-SiC prepared via direct microwave heating follows the mechanism of two-dimension nucleation and laminar growth. - Highlights: • 3C−SiC grains/nanowires were obtained via direct microwave heating. • 3C−SiC followed the mechanism of two-dimension nucleation and laminar growth. • In-situ EBSD analysis provided the experimental evidences of the growth.

  4. Skating mechanics of change-of-direction manoeuvres in ice hockey players.

    Science.gov (United States)

    Fortier, Antoine; Turcotte, René A; Pearsall, David J

    2014-11-01

    Ice hockey requires rapid transitions between skating trajectories to effectively navigate about the ice surface. Player performance relates in large part to effective change-of-direction manoeuvres, but little is known about how those skills are performed mechanically and the effect of equipment design on them. The purpose of this study was to observe the kinetics involved in those manoeuvres as well as to compare whether kinetic differences may result between two skate models of varying ankle mobility. Eight subjects with competitive ice hockey playing experience performed rapid lateral (90°) left and right change-of-direction manoeuvres. Kinetic data were collected using force strain gauge transducers on the blade holders of the skates. Significantly greater forces were applied by the outside skate (50-70% body weight, %BW) in comparison to the inside skate (12-24%BW, p Skate model and turn direction had no main effect, though significant mixed interactions between leg side (inside/outside) with skate model or turn direction (p skating change-of-direction tasks.

  5. Comparison of Rice Direct Seeding Methods (Mechanical and Manual with Transplanting Method

    Directory of Open Access Journals (Sweden)

    A Eyvani

    2014-04-01

    Full Text Available The main method of rice planting in Iran is transplanting. Due to poor mechanization of rice production, this method is laborious and costly. The other method is direct seeding in wet lands which is performed in the one third of rice cultivation area of the world. The most important problem in this method is high labor requirement of weed control. In order to compare the different rice planting methods (direct drilling, transplanting, and seed broadcasting a manually operated rice direct seeder (drum seeder was designed and fabricated. The research was conducted using a randomized complete block design with three treatments and three replications. Required draft force, field efficiency, effective field capacity, yield, and yield components were measured and the treatments were compared economically. Results showed that there were significant differences among the treatments from the view point of rice yield at the confidence level of 95% i.e. the transplanting method had the maximum yield. A higher rice yield was obtained from the direct seeder compared to the manual broadcasting method but, the difference between these two methods for crop yield was not significant even at the confidence level of the 95%. The coefficient of variation of seed distribution with direct seeding was more than 20%. The labor and time requirements per hectare reduced to 7 and 20 times, respectively when comparing the newly designed direct seeder with the transplanting method. The direct seeding method had the highest benefit to cost ratio in spite of its lower yield. Therefore, this method could be recommended in the rice growing regions.

  6. Intraplate Crustal Deformation Within the Northern Sinai Microplate: Evidence from Paleomagnetic Directions and Mechanical Modeling

    Science.gov (United States)

    Dembo, N.; Granot, R.; Hamiel, Y.

    2017-12-01

    The intraplate crustal deformation found in the northern part of the Sinai Microplate, located near the northern Dead Sea Fault plate boundary, is examined. Previous studies have suggested that distributed deformation in Lebanon is accommodated by regional uniform counterclockwise rigid block rotations. However, remanent magnetization directions observed near the Lebanese restraining bend are not entirely homogeneous suggesting that an unexplained and complex internal deformation pattern exists. In order to explain the variations in the amount of vertical-axis rotations we construct a mechanical model of the major active faults in the region that simulates the rotational deformation induced by motion along these faults. The rotational pattern calculated by the mechanical modeling predicts heterogeneous distribution of rotations around the faults. The combined rotation field that considers both the fault induced rotations and the already suggested regional block rotations stands in general agreement with the observed magnetization directions. Overall, the modeling results provide a more detailed and complete picture of the deformation pattern in this region and show that rotations induced by motion along the Dead Sea Fault act in parallel to rigid block rotations. Finally, the new modeling results unravel important insights as to the fashion in which crustal deformation is distributed within the northern part of the Sinai Microplate and propose an improved deformational mechanism that might be appropriate for other plate margins as well.

  7. A direct comparison of the defense mechanisms of nondepressed people and depressed psychiatric inpatients.

    Science.gov (United States)

    Margo, G M; Greenberg, R P; Fisher, S; Dewan, M

    1993-01-01

    This report presents a direct comparison of defensive styles (as measured by the Defense Mechanisms Inventory [DMI]) in a sample of depressed psychiatric inpatients and samples of nondepressed male and female normative groups. Consistent with the "depressive realism" literature, nondepressed men and women were more likely than their depressed counterparts to bias their perceptions in an overly cheerful, optimistic direction. Counternormative sex differences were also found. Depressed men were more likely to use internalizing defenses and depressed women were more likely to use externalizing defenses than their respective nondepressed comparison groups. Overall, as has been speculated, there was a relationship within depressed subjects between depression severity and the amount of negatively biased self-perception.

  8. FUZZY LOGIC BASED ADAPTATION MECHANISM FOR ADAPTIVE LUENBERGER OBSERVER SENSORLESS DIRECT TORQUE CONTROL OF INDUCTION MOTOR

    Directory of Open Access Journals (Sweden)

    A. BENNASSAR

    2016-01-01

    Full Text Available Many industrial applications require high performance speed sensorless operation and demand new control methods in order to obtain fast dynamic response and insensitive to external disturbances. The current research aims to present the performance of the sensorless direct torque control (DTC of an induction motor (IM using adaptive Luenberger observer (ALO with fuzzy logic controller (FLC for adaptation mechanism. The rotor speed is regulated by proportional integral (PI anti-windup controller. The proposed strategy is directed to reduce the ripple on the torque and the flux. Numerical simulation results show the good performance and effectiveness of the proposed sensorless control for different references of the speed even both low and high speeds.

  9. Nonlinear mechanics of thin-walled structures asymptotics, direct approach and numerical analysis

    CERN Document Server

    Vetyukov, Yury

    2014-01-01

    This book presents a hybrid approach to the mechanics of thin bodies. Classical theories of rods, plates and shells with constrained shear are based on asymptotic splitting of the equations and boundary conditions of three-dimensional elasticity. The asymptotic solutions become accurate as the thickness decreases, and the three-dimensional fields of stresses and displacements can be determined. The analysis includes practically important effects of electromechanical coupling and material inhomogeneity. The extension to the geometrically nonlinear range uses the direct approach based on the principle of virtual work. Vibrations and buckling of pre-stressed structures are studied with the help of linearized incremental formulations, and direct tensor calculus rounds out the list of analytical techniques used throughout the book. A novel theory of thin-walled rods of open profile is subsequently developed from the models of rods and shells, and traditionally applied equations are proven to be asymptotically exa...

  10. A dendrite-autonomous mechanism for direction selectivity in retinal starburst amacrine cells.

    Science.gov (United States)

    Hausselt, Susanne E; Euler, Thomas; Detwiler, Peter B; Denk, Winfried

    2007-07-01

    Detection of image motion direction begins in the retina, with starburst amacrine cells (SACs) playing a major role. SACs generate larger dendritic Ca(2+) signals when motion is from their somata towards their dendritic tips than for motion in the opposite direction. To study the mechanisms underlying the computation of direction selectivity (DS) in SAC dendrites, electrical responses to expanding and contracting circular wave visual stimuli were measured via somatic whole-cell recordings and quantified using Fourier analysis. Fundamental and, especially, harmonic frequency components were larger for expanding stimuli. This DS persists in the presence of GABA and glycine receptor antagonists, suggesting that inhibitory network interactions are not essential. The presence of harmonics indicates nonlinearity, which, as the relationship between harmonic amplitudes and holding potential indicates, is likely due to the activation of voltage-gated channels. [Ca(2+)] changes in SAC dendrites evoked by voltage steps and monitored by two-photon microscopy suggest that the distal dendrite is tonically depolarized relative to the soma, due in part to resting currents mediated by tonic glutamatergic synaptic input, and that high-voltage-activated Ca(2+) channels are active at rest. Supported by compartmental modeling, we conclude that dendritic DS in SACs can be computed by the dendrites themselves, relying on voltage-gated channels and a dendritic voltage gradient, which provides the spatial asymmetry necessary for direction discrimination.

  11. A dendrite-autonomous mechanism for direction selectivity in retinal starburst amacrine cells.

    Directory of Open Access Journals (Sweden)

    Susanne E Hausselt

    2007-07-01

    Full Text Available Detection of image motion direction begins in the retina, with starburst amacrine cells (SACs playing a major role. SACs generate larger dendritic Ca(2+ signals when motion is from their somata towards their dendritic tips than for motion in the opposite direction. To study the mechanisms underlying the computation of direction selectivity (DS in SAC dendrites, electrical responses to expanding and contracting circular wave visual stimuli were measured via somatic whole-cell recordings and quantified using Fourier analysis. Fundamental and, especially, harmonic frequency components were larger for expanding stimuli. This DS persists in the presence of GABA and glycine receptor antagonists, suggesting that inhibitory network interactions are not essential. The presence of harmonics indicates nonlinearity, which, as the relationship between harmonic amplitudes and holding potential indicates, is likely due to the activation of voltage-gated channels. [Ca(2+] changes in SAC dendrites evoked by voltage steps and monitored by two-photon microscopy suggest that the distal dendrite is tonically depolarized relative to the soma, due in part to resting currents mediated by tonic glutamatergic synaptic input, and that high-voltage-activated Ca(2+ channels are active at rest. Supported by compartmental modeling, we conclude that dendritic DS in SACs can be computed by the dendrites themselves, relying on voltage-gated channels and a dendritic voltage gradient, which provides the spatial asymmetry necessary for direction discrimination.

  12. Microstructure and mechanical properties of direct metal laser sintered TI-6AL-4V

    Directory of Open Access Journals (Sweden)

    Becker, Thorsten Hermann

    2015-05-01

    Full Text Available Direct metal laser sintering (DMLS is a selective laser melting (SLM manufacturing process that can produce near net shape parts from metallic powders. A range of materials are suitable for SLM; they include various metals such as titanium, steel, aluminium, and cobalt-chrome alloys. This paper forms part of a research drive that aims to evaluate the material performance of the SLM-manufactured metals. It presents DMLS-produced Ti-6Al-4V, a titanium alloy often used in biomedical and aerospace applications. This paper also studies the effect of several heat treatments on the microstructure and mechanical properties of Ti-6Al-4V processed by SLM. It reports the achievable mechanical properties of the alloy, including quasi-static, crack growth behaviour, density and porosity distribution, and post-processing using various heat-treatment conditions.

  13. Direct synthesis of BiCuChO-type oxychalcogenides by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Pele, Vincent; Barreteau, Celine [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France); Berardan, David, E-mail: david.berardan@u-psud.fr [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France); Zhao, Lidong; Dragoe, Nita [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France)

    2013-07-15

    We report on the direct synthesis of BiCuChO based materials by mechanical alloying (Ch=Se, Te). We show that contrary to the synthesis paths used in the previous reports dealing with this family of materials, which use costly annealings in closed silica tubes under controlled atmosphere, this new synthesis route enables the synthesis of pure phase materials at room temperature under air, with reasonable milling time. This synthesis procedure is easily scalable for large scale applications. - Highlights: • Phase pure BiCuSeO doped and undoped prepared by mechanical alloying. • Synthesis performed under air at room temperature. • Electrical properties similar to that of samples synthesized by a classical path.

  14. Microstructure and mechanical property of dual-directional-extruded Mg alloy AZ31

    International Nuclear Information System (INIS)

    Lu Liwei; Liu Tianmo; Jiang Shan; Pan Fushen; Liu Qing; Wang Zhongchang

    2010-01-01

    We report microstructure evolution and mechanical property of Mg alloy AZ31 processed by a new deformation technique, dual-directional extrusion (DDE). Using optical microscopy, scanning electron microscopy, and electron back scatter diffraction technique, we attribute the significant refinement of original coarse grains in the DDE-processed alloy to the occurrence of dynamic recrystallization. Moreover, we find that low temperature is crucial for yielding fine grain, which consequently results in high micro-hardness and yield stress, large fracture strain, and enhanced elongation. The improved mechanical properties are comparable or even superior to those of the alloy subjected to other deformation techniques, rendering the DDE a promising way for further tailoring properties of Mg-based alloys.

  15. A review of Green's function methods in computational fluid mechanics: Background, recent developments and future directions

    International Nuclear Information System (INIS)

    Dorning, J.

    1981-01-01

    The research and development over the past eight years on local Green's function methods for the high-accuracy, high-efficiency numerical solution of nuclear engineering problems is reviewed. The basic concepts and key ideas are presented by starting with an expository review of the original fully two-dimensional local Green's function methods developed for neutron diffusion and heat conduction, and continuing through the progressively more complicated and more efficient nodal Green's function methods for neutron diffusion, heat conduction and neutron transport to establish the background for the recent development of Green's function methods in computational fluid mechanics. Some of the impressive numerical results obtained via these classes of methods for nuclear engineering problems are briefly summarized. Finally, speculations are proffered on future directions in which the development of these types of methods in fluid mechanics and other areas might lead. (orig.) [de

  16. Mechanism of action of direct-acting antiviral agents in treatment of chronic hepatitis C

    Directory of Open Access Journals (Sweden)

    WEN Xiaoyu

    2016-09-01

    Full Text Available With the development and launch of direct-acting antiviral agents (DAAs in the world in recent years, therapeutic regimens for chronic hepatitis C are constantly evolving. DAAs will also be launched in China in the near future. DAAs mainly target at the non-structural proteins of HCV and can inhibit HCV RNA replication. This article introduces the targets, mechanism of action, and resistance characteristics of different DAAs, as well as their current research and development in China and the results of phase Ⅲ clinical studies, in order to provide a reference for combined therapeutic strategies with DAAs in the treatment for chronic hepatitis C.

  17. Direct Visualization of Mechanical Beats by Means of an Oscillating Smartphone

    Science.gov (United States)

    Giménez, Marcos H.; Salinas, Isabel; Monsoriu, Juan A.; Castro-Palacio, Juan C.

    2017-10-01

    The resonance phenomenon is widely known in physics courses. Qualitatively speaking, resonance takes place in a driven oscillating system whenever the frequency approaches the natural frequency, resulting in maximal oscillatory amplitude. Very closely related to resonance is the phenomenon of mechanical beating, which occurs when the driving and natural frequencies of the system are slightly different. The frequency of the beat is just the difference of the natural and driving frequencies. Beats are very familiar in acoustic systems. There are several works in this journal on visualizing the beats in acoustic systems. For instance, the microphone and the speaker of two mobile devices were used in previous work to analyze the acoustic beats produced by two signals of close frequencies. The formation of beats can also be visualized in mechanical systems, such as a mass-spring system or a double-driven string. Here, the mechanical beats in a smartphone-spring system are directly visualized in a simple way. The frequency of the beats is measured by means of the acceleration sensor of a smartphone, which hangs from a spring attached to a mechanical driver. This laboratory experiment is suitable for both high school and first-year university physics courses.

  18. ASSESSMENT OF POTENTIAL TSUNAMI GENERATION IN CHINA'S BOHAI SEA FROM DIRECT GEOTECTONIC AND COLLATERAL SOURCE MECHANISMS

    Directory of Open Access Journals (Sweden)

    G. Pararas Carayannis

    2009-01-01

    Full Text Available The Bohai Sea borders northeastern China's most populous and highest economic valuecoastal areas where several megacities are located. Critical infrastructure facilities exist or areunder construction, including a nuclear power plant and super port facilities. Large reserves of oilhave been discovered and a number of offshore oil platforms have been built. The extent ofdevelopment along coastal areas requires a better assessment of potential tsunami risks. Althoughtsunamis do not pose as much of a threat as earthquakes in this region, locally destructive tsunamishave been generated in the past and future events could have significant impacts on coastalpopulations and China's economy, particularly because most of the development has taken place inlow-lying regions, including river deltas. The present study examines the geotectonics of the Bohaibasin region, the impact of past historical events, and the potential for local tsunami generationfrom a variety of direct and collateral source mechanisms triggered by intra plate earthquakes.More specifically, the present study examines: amajor active faults bounding the Bohai Basin; bthe resulting crustal deformation patterns of tectonic structures that have resulted in catastrophicearthquakes in recent years; c the basin-wide extension - with local inversion - extending into theBohai Sea that generated tsunamigenic earthquakes in 1888 and 1969; and d deformational futureseismic events with the potential to generate local tsunamis directly or by collateral mechanisms offolding, en-echelon bookshelf failures, or from destabilization/dissociation of structuralaccumulations of gas hydrate deposits within the basin's thick sedimentary stratigraphic layers.

  19. Direct laser sintering of metal powders: Mechanism, kinetics and microstructural features

    International Nuclear Information System (INIS)

    Simchi, A.

    2006-01-01

    In the present work, the densification and microstructural evolution during direct laser sintering of metal powders were studied. Various ferrous powders including Fe, Fe-C, Fe-Cu, Fe-C-Cu-P, 316L stainless steel, and M2 high-speed steel were used. The empirical sintering rate data was related to the energy input of the laser beam according to the first order kinetics equation to establish a simple sintering model. The equation calculates the densification of metal powders during direct laser sintering process as a function of operating parameters including laser power, scan rate, layer thickness and scan line spacing. It was found that when melting/solidification approach is the mechanism of sintering, the densification of metals powders (D) can be expressed as an exponential function of laser specific energy input (ψ) as ln(1 - D) = -Kψ. The coefficient K is designated as 'densification coefficient'; a material dependent parameter that varies with chemical composition, powder particle size, and oxygen content of the powder material. The mechanism of particle bonding and microstructural features of the laser sintered powders are addressed

  20. Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization.

    Science.gov (United States)

    Zhang, H-S; Komvopoulos, K

    2008-07-01

    Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp3) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study.

  1. Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization

    International Nuclear Information System (INIS)

    Zhang, H.-S.; Komvopoulos, K.

    2008-01-01

    Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp 3 ) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study

  2. Direct mechanical data acquisition of dental impressions for the manufacturing of CAD/CAM restorations.

    Science.gov (United States)

    Quaas, Sebastian; Rudolph, Heike; Luthardt, Ralph G

    2007-12-01

    The basic prerequisite for the production of dental restorations by means of CAD/CAM technologies is the data acquisition (digitization). Currently, two methods are available, i.e. the extraoral digitization of master casts and the direct intraoral data acquisition. However, it seems to be beneficial to immediately digitize impressions directly at the dental office in order to combine the high precision of mechanical digitizing methods and to shorten the production process. The aim of this study was to investigate the measurement uncertainty (+/-2sigma) and the three-dimensional accuracy of the immediate tactile in-office digitization of dental impressions and of the mechanical digitizing of ceramic master dies using a high-precision touch-probe digitizer. The experimental set-up consisted of ceramic master dies representing tooth 13 and 36 as well as their identical virtual models (CAD models). Fifteen one-step putty-wash impressions were taken from each tooth. The impressions as well as the ceramic master dies were digitized applying a standardized procedure. The datasets were aligned to the corresponding CAD models; then, a computer-aided three-dimensional analysis was performed. The digitizing of the dental impressions showed a measurement uncertainty of 5.8, mean positive deviations between 27 and 28microm, and mean negative deviations between -21 and -31microm. The digitizing of the ceramic master dies showed a measurement uncertainty of 2.8, mean positive deviations between 7.7 and 9.1microm, and mean negative deviations between -8.5 and -8.8microm. Mechanical digitizers show a very low measurement uncertainty and a high precision. The immediate tactile in-office digitization of impressions cannot be recommended as adequate data acquisition method for CAD/CAM restorations. It is recommendable to digitize clinical sites extraorally, i.e. after taking an impression and fabricating a model cast thereof.

  3. Morphogenetic mechanisms of coelom formation in the direct-developing sea urchin Heliocidaris erythrogramma.

    Science.gov (United States)

    Smith, Margaret S; Collins, Steve; Raff, Rudolf A

    2009-01-01

    Indirect development via a feeding pluteus larva represents the ancestral mode of sea urchin development. However, some sea urchin species exhibit a derived form of development, called direct development, in which features of the feeding larva are replaced by accelerated development of the adult. A major difference between these two developmental modes is the timing of the formation of the left coelom and initiation of adult development. These processes occur much earlier in developmental and absolute time in direct developers and may be underlain by changes in morphogenetic processes. In this study, we explore whether differences in the cellular mechanisms responsible for the development of the left coelom and adult structures are associated with the change in the timing of their formation in the direct-developing sea urchin Heliocidaris erythrogramma. We present evidence that left coelom formation in H. erythrogramma, which differs in major aspects of coelom formation in indirect developers, is not a result of cell division. Further, we demonstrate that subsequent development of adult structures requires cell division.

  4. Neural mechanisms underlying transcranial direct current stimulation in aphasia: A feasibility study.

    Directory of Open Access Journals (Sweden)

    Lena eUlm

    2015-10-01

    Full Text Available Little is known about the neural mechanisms by which transcranial direct current stimulation (tDCS impacts on language processing in post-stroke aphasia. This was addressed in a proof-of-principle study that explored the effects of tDCS application in aphasia during simultaneous functional magnetic resonance imaging (fMRI. We employed a single subject, cross-over, sham-tDCS controlled design and the stimulation was administered to an individualized perilesional stimulation site that was identified by a baseline fMRI scan and a picture naming task. Peak activity during the baseline scan was located in the spared left inferior frontal gyrus (IFG and this area was stimulated during a subsequent cross-over phase. tDCS was successfully administered to the target region and anodal- vs. sham-tDCS resulted in selectively increased activity at the stimulation site. Our results thus demonstrate that it is feasible to precisely target an individualized stimulation site in aphasia patients during simultaneous fMRI which allows assessing the neural mechanisms underlying tDCS application. The functional imaging results of this case report highlight one possible mechanism that may have contributed to beneficial behavioural stimulation effects in previous clinical tDCS trials in aphasia. In the future, this approach will allow identifying distinct patterns of stimulation effects on neural processing in larger cohorts of patients. This may ultimately yield information about the variability of tDCS-effects on brain functions in aphasia.

  5. Mechanism and bias considerations for design of a bi-directional pneumatic artificial muscle actuator

    International Nuclear Information System (INIS)

    Vocke III, Robert D; Wereley, Norman M; Kothera, Curt S

    2014-01-01

    Pneumatic artificial muscles (PAMs), or McKibben actuators, have received considerable attention for robotic manipulators and in aerospace applications due to their similarity to natural muscles. Like natural muscles, PAMs are a purely contractile actuator, so that, in order to produce bi-directional or rotational motion, they must be arranged in an agonist/antagonist pair, which inherently limits the deflection of the system due to the high parasitic stiffness of the antagonistic PAM. This study presents two methods for increasing the performance of an antagonistic PAM system by decreasing the passive parasitic torque, rather than increasing the active torque. The first involves selection of the kinematic mechanism geometry, and the second involves the introduction of bias into the system, both in terms of PAM contraction and passive (antagonistic) PAM pressure. It was found with the proper selection of design parameters, including mechanism geometry, PAM geometry, and bias conditions, that an ideal actuator configuration can be chosen that maximizes deflection for a given arbitrary loading. When comparing a baseline design to an improved design for a simplified case, a nearly 50% increase in maximum deflection was predicted simply by optimizing mechanism geometry and bias contraction. These results were experimentally verified with quasi-static testing that showed a 300% increase in actuator deflection over the baseline design. (paper)

  6. Theoretical modeling of mechanical homeostasis of a mammalian cell under gravity-directed vector.

    Science.gov (United States)

    Zhou, Lüwen; Zhang, Chen; Zhang, Fan; Lü, Shouqin; Sun, Shujin; Lü, Dongyuan; Long, Mian

    2018-02-01

    Translocation of dense nucleus along gravity vector initiates mechanical remodeling of a eukaryotic cell. In our previous experiments, we quantified the impact of gravity vector on cell remodeling by placing an MC3T3-E1 cell onto upward (U)-, downward (D)-, or edge-on (E)- orientated substrate. Our experimental data demonstrate that orientation dependence of nucleus longitudinal translocation is positively correlated with cytoskeletal (CSK) remodeling of their expressions and structures and also is associated with rearrangement of focal adhesion complex (FAC). However, the underlying mechanism how CSK network and FACs are reorganized in a mammalian cell remains unclear. In this paper, we developed a theoretical biomechanical model to integrate the mechanosensing of nucleus translocation with CSK remodeling and FAC reorganization induced by a gravity vector. The cell was simplified as a nucleated tensegrity structure in the model. The cell and CSK filaments were considered to be symmetrical. All elements of CSK filaments and cytomembrane that support the nucleus were simplified as springs. FACs were simplified as an adhesion cluster of parallel bonds with shared force. Our model proposed that gravity vector-directed translocation of the cell nucleus is mechanically balanced by CSK remodeling and FAC reorganization induced by a gravitational force. Under gravity, dense nucleus tends to translocate and exert additional compressive or stretching force on the cytoskeleton. Finally, changes of the tension force acting on talin by microfilament alter the size of FACs. Results from our model are in qualitative agreement with those from experiments.

  7. Action mechanisms of transcranial direct current stimulation in Alzheimer´s disease and memory loss

    Directory of Open Access Journals (Sweden)

    Niels eHansen

    2012-05-01

    Full Text Available The pharmacological treatment of Alzheimer´s disease (AD is often limited and accompanied by drug side effects. Thus alternative therapeutic strategies such as non-invasive brain stimulation are needed. Few studies have demonstrated that transcranial direct current stimulation (tDCS, a method of neuromodulation with consecutive robust excitability changes within the stimulated cortex area, is beneficial in AD. There is also evidence that tDCS enhances memory function in cognitive rehabilitation in depressive patients, Parkinson´s disease and stroke. TDCS improves working and visual recognition memory in humans and object-recognition learning in the elderly. Neurobiological mechanisms of AD comprise changes in neuronal activity and the cerebral blood flow caused by altered microvasculature, synaptic dysregulation from ß-amyloid peptide accumulation, altered neuromodulation by degeneration of modulatory amine transmitter systems, altered brain oscillations, and changes in network connectivity. tDCS alters (i neuronal activity and (ii human cerebral blood flow, (iii has synaptic and non-synaptic after-effects (iv, can modify neurotransmitters polarity-dependently, (v and alter oscillatory brain activity and (vi functional connectivity patterns in the brain. It thus is reasonable to use tDCS as a therapeutic instrument in AD as it improves cognitive function in manner based on a disease mechanism. Moreover, it might prove valuable in other types of dementia. Future large-scale clinical and mechanism-oriented studies may enable to identify its therapeutic validity in other types of demential disorders.

  8. Action mechanisms of transcranial direct current stimulation in Alzheimer's disease and memory loss.

    Science.gov (United States)

    Hansen, Niels

    2012-01-01

    The pharmacological treatment of Alzheimer's disease (AD) is often limited and accompanied by drug side effects. Thus alternative therapeutic strategies such as non-invasive brain stimulation are needed. Few studies have demonstrated that transcranial direct current stimulation (tDCS), a method of neuromodulation with consecutive robust excitability changes within the stimulated cortex area, is beneficial in AD. There is also evidence that tDCS enhances memory function in cognitive rehabilitation in depressive patients, Parkinson's disease, and stroke. tDCS improves working and visual recognition memory in humans and object-recognition learning in the elderly. AD's neurobiological mechanisms comprise changes in neuronal activity and the cerebral blood flow (CBF) caused by altered microvasculature, synaptic dysregulation from ß-amyloid peptide accumulation, altered neuromodulation via degenerated modulatory amine transmitter systems, altered brain oscillations, and changes in network connectivity. tDCS alters (i) neuronal activity and (ii) human CBF, (iii) has synaptic and non-synaptic after-effects (iv), can modify neurotransmitters polarity-dependently, (v) and alter oscillatory brain activity and (vi) functional connectivity patterns in the brain. It thus is reasonable to use tDCS as a therapeutic instrument in AD as it improves cognitive function in manner based on a disease mechanism. Moreover, it could prove valuable in other types of dementia. Future large-scale clinical and mechanism-oriented studies may enable us to identify its therapeutic validity in other types of demential disorders.

  9. Mechanical characteristics of a tool steel layer deposited by using direct energy deposition

    Science.gov (United States)

    Baek, Gyeong Yun; Shin, Gwang Yong; Lee, Eun Mi; Shim, Do Sik; Lee, Ki Yong; Yoon, Hi-Seak; Kim, Myoung Ho

    2017-07-01

    This study focuses on the mechanical characteristics of layered tool steel deposited using direct energy deposition (DED) technology. In the DED technique, a laser beam bonds injected metal powder and a thin layer of substrate via melting. In this study, AISI D2 substrate was hardfaced with AISI H13 and M2 metal powders for mechanical testing. The mechanical and metallurgical characteristics of each specimen were investigated via microstructure observation and hardness, wear, and impact tests. The obtained characteristics were compared with those of heat-treated tool steel. The microstructures of the H13- and M2-deposited specimens show fine cellular-dendrite solidification structures due to melting and subsequent rapid cooling. Moreover, the cellular grains of the deposited M2 layer were smaller than those of the H13 structure. The hardness and wear resistance were most improved in the M2-deposited specimen, yet the H13-deposited specimen had higher fracture toughness than the M2-deposited specimen and heat-treated D2.

  10. Fatigue behavior and failure mechanisms of direct laser deposited Ti–6Al–4V

    Energy Technology Data Exchange (ETDEWEB)

    Sterling, Amanda J.; Torries, Brian [Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762 (United States); Shamsaei, Nima, E-mail: shamsaei@me.msstate.edu [Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762 (United States); Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, , Mississippi State, MS 39762 (United States); Thompson, Scott M. [Department of Mechanical Engineering, Mississippi State University, Box 9552, Mississippi State, MS 39762 (United States); Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, , Mississippi State, MS 39762 (United States); Seely, Denver W. [Center for Advanced Vehicular Systems (CAVS), Mississippi State University, Box 5405, , Mississippi State, MS 39762 (United States)

    2016-02-08

    In order for additive-manufactured parts to become more widely utilized and trusted in application, it is important to have their mechanical properties well-characterized and certified. The fatigue behavior and failure mechanisms of Ti–6Al–4V specimens fabricated using Laser Engineered Net Shaping (LENS), a Direct Laser Deposition (DLD) additive manufacturing (AM) process, are investigated in this study. A series of fully-reversed strain-controlled fatigue tests is conducted on Ti–6Al–4V specimens manufactured via LENS in their as-built and heat-treated conditions. Scanning Electron Microscopy (SEM) is used to examine the fracture surfaces of fatigue specimens to qualify the failure mechanism, crack initiation sites, and defects such as porosity. Due to the relatively high localized heating and cooling rates experienced during DLD, fabricated parts are observed to possess anisotropic microstructures, and thus, different mechanical properties than those of their traditionally-manufactured wrought counterparts. The fatigue lives of the investigated LENS specimens were found to be shorter than those of wrought specimens, and porosity was found to be the primary contributor to these shorter fatigue lives, with the exception of the heat-treated LENS samples. The presence of pores promotes more unpredictable fatigue behavior, as evidenced by data scatter. Pore shape, size, location, and number were found to impact the fatigue behavior of the as-built and annealed DLD parts. As porosity seems to be the main contributor to the fatigue behavior of DLD parts, it is important to optimize the manufacturing process and design parameters to minimize and control pore generation during the build.

  11. Direct testing of the biasing effect of manipulations of endolymphatic pressure on cochlear mechanical function

    Science.gov (United States)

    LePage, Eric; Avan, Paul

    2015-12-01

    The history of cochlear mechanical investigations has been carried out in two largely separate sets of endeavours; those interested in auditory processing in animal models and those interested in the origin of adverse vestibular symptoms in humans. In respect of the first, mechanical vibratory data is considered pathological and not representative of pristine behaviour if it departs from the reigning model of sharp tuning and high hearing sensitivity. Conversely, when the description of the pathological behaviour is the focus, fluid movements responsible for hearing loss and vestibular symptoms dominate. Yet both extensive sets of data possess a common factor now being reconsidered for its potential to shed light on the mechanisms in general. The common factor is a mechanical bias — the departure of cochlear epithelial membranes from their usual resting position. In both cases the bias modulates hearing sensitivity and distorts tuning characteristics. Indeed several early sets of guinea pig mechanical data were dismissed as "pathological" when in hindsight, the primary effect influencing the data was not loss of outer hair cell function per se, but a mechanical bias unknowingly introduced in process of making the measurement. Such biases in the displacement of the basilar membrane from its position are common, and may be caused by low-frequency sounds (topically including infrasound) or by variations in fluid volume in the chambers particularly applying the case of endolymphatic hydrops. Most biases are quantified in terms of visualisation of fluid volume change, electric potential changes and otoacoustic emissions. Notably many previous studies have also searched for raised pressures with negative results. Yet these repeated findings are contrary to the widespread notion that, at least when homeostasis is lost, it is a rise in endolymphatic pressure which is responsible for membrane rupture and Meniere's attacks. This current investigation in Mongolian gerbils

  12. Mechanical stimulation induces mTOR signaling via an ERK-independent mechanism: implications for a direct activation of mTOR by phosphatidic acid.

    Directory of Open Access Journals (Sweden)

    Jae Sung You

    Full Text Available Signaling by mTOR is a well-recognized component of the pathway through which mechanical signals regulate protein synthesis and muscle mass. However, the mechanisms involved in the mechanical regulation of mTOR signaling have not been defined. Nevertheless, recent studies suggest that a mechanically-induced increase in phosphatidic acid (PA may be involved. There is also evidence which suggests that mechanical stimuli, and PA, utilize ERK to induce mTOR signaling. Hence, we reasoned that a mechanically-induced increase in PA might promote mTOR signaling via an ERK-dependent mechanism. To test this, we subjected mouse skeletal muscles to mechanical stimulation in the presence or absence of a MEK/ERK inhibitor, and then measured several commonly used markers of mTOR signaling. Transgenic mice expressing a rapamycin-resistant mutant of mTOR were also used to confirm the validity of these markers. The results demonstrated that mechanically-induced increases in p70(s6k T389 and 4E-BP1 S64 phosphorylation, and unexpectedly, a loss in total 4E-BP1, were fully mTOR-dependent signaling events. Furthermore, we determined that mechanical stimulation induced these mTOR-dependent events, and protein synthesis, through an ERK-independent mechanism. Similar to mechanical stimulation, exogenous PA also induced mTOR-dependent signaling via an ERK-independent mechanism. Moreover, PA was able to directly activate mTOR signaling in vitro. Combined, these results demonstrate that mechanical stimulation induces mTOR signaling, and protein synthesis, via an ERK-independent mechanism that potentially involves a direct interaction of PA with mTOR. Furthermore, it appears that a decrease in total 4E-BP1 may be part of the mTOR-dependent mechanism through which mechanical stimuli activate protein synthesis.

  13. Metallurgical and Mechanical Evaluation of 4340 Steel Produced by Direct Metal Laser Sintering

    Science.gov (United States)

    Jelis, Elias; Clemente, Matthew; Kerwien, Stacey; Ravindra, Nuggehalli M.; Hespos, Michael R.

    2015-03-01

    Direct metal laser sintering (DMLS) was used to produce high-strength low-alloy 4340 steel specimens. Mechanical and metallurgical analyses were performed on the specimens to determine the samples with the highest strengths and the least porosity. The optimal process parameters were thus defined based on the corresponding experimental conditions. Additionally, the effects of fabricating specimens with both virgin and recycled powders were studied. Scanning electron microscopy and electron-dispersive spectroscopy were performed on both types of powders to determine the starting morphology and composition. The initial tensile results are promising, suggesting that DMLS can produce specimens equal in strength to wrought materials. However, there is evidence of cracking on several of the heat-treated tensile specimens that is unexplained. Several theories point to disturbances in the build chamber environment that went undetected while the specimens were being fabricated.

  14. Statistical mechanical characteristics of slip-ring induction motors when direct current braking

    Energy Technology Data Exchange (ETDEWEB)

    Kedzior, W; Muchorowski, J; Pienkowski, K

    1980-09-01

    This paper evaluates methods of braking high capacity belt conveyors used in brown coal surface mines in Poland. Complications associated with belt conveyor braking, particularly when a conveyor moves down a slope, are analyzed. A method of calculating mechanical characteristics of wound-rotor induction motors during direct current braking taking into account saturation of magnetic circuit is presented. Characteristics of the SZUr motor with 630 kW power, used in brown coal mining, are also given. Analyses show that motor operation can be efficiently braked in two ways: 1. by changing additional resistance in rotor circuit (e.g. using thyristor controller); 2. by changing intensity of electric current supplied to stator winding (e.g. using a rectifier). (3 refs.) (In Polish)

  15. Direct observation of TALE protein dynamics reveals a two-state search mechanism.

    Science.gov (United States)

    Cuculis, Luke; Abil, Zhanar; Zhao, Huimin; Schroeder, Charles M

    2015-06-01

    Transcription activator-like effector (TALE) proteins are a class of programmable DNA-binding proteins for which the fundamental mechanisms governing the search process are not fully understood. Here we use single-molecule techniques to directly observe TALE search dynamics along DNA templates. We find that TALE proteins are capable of rapid diffusion along DNA using a combination of sliding and hopping behaviour, which suggests that the TALE search process is governed in part by facilitated diffusion. We also observe that TALE proteins exhibit two distinct modes of action during the search process-a search state and a recognition state-facilitated by different subdomains in monomeric TALE proteins. Using TALE truncation mutants, we further demonstrate that the N-terminal region of TALEs is required for the initial non-specific binding and subsequent rapid search along DNA, whereas the central repeat domain is required for transitioning into the site-specific recognition state.

  16. MECHANICAL PROPERTIES OF THIN GDP SHELLS USED AS CRYOGENIC DIRECT DRIVE TARGETS AT OMEGA

    International Nuclear Information System (INIS)

    NIKROO, A.; CZECHOWICZ, D.; CHEN, K.C.; DICKEN, M.; MORRIS, C.; ANDREWS, R.; GREENWOOD, A.L; CASTILLO, E.

    2003-09-01

    OAK-B135 Thin glow discharge polymer (GDP) shells are currently used as the targets for cryogenic direct drive laser fusion experiments. These shells need to be filled with nearly 1000 atm of D 2 and cooled to cryogenic temperatures without failing due to buckling and bursting pressures they experience in this process. Therefore, the mechanical and permeation properties of these shells are of utmost importance in successful and rapid filling with D 2 . In this paper, they present an overview of buckle and burst pressures of several different types of GDP shells. These include those made using traditional GDP deposition parameters (standard GDP) using a high deposition pressure and using modified parameters (strong GDP) of low deposition pressure that leads to more robust shells

  17. Photoactuators for Direct Optical-to-Mechanical Energy Conversion: From Nanocomponent Assembly to Macroscopic Deformation.

    Science.gov (United States)

    Hu, Ying; Li, Zhe; Lan, Tian; Chen, Wei

    2016-12-01

    Photoactuators with integrated optical-to-mechanical energy conversion capacity have attracted growing research interest in the last few decades due to their unique features of remote control and their wide applications ranging from bionic robots, biomedical devices, and switches to motors. For the photoactuator design, the energy conversion route and structure assembly are two important parts, which directly affect the performance of the photoactuators. In particular, the architectural designs at the molecular, nano-, micro-, and macro- level, are found to play a significant role in accumulating molecular-scale strain/stress to macroscale strain/stress. Here, recent progress on photoactuators based on photochemical and photothermal effects is summarized, followed by a discussion of the important assembly strategies for the amplification of the photoresponsive components at nanoscale to macroscopic scale motions. The application advancement of current photoactuators is also presented. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Cooperation mechanisms of the EU renewable energy directive and flexible mechanisms of the Kyoto Protocol: comparison and lessons learnt. Working paper

    Energy Technology Data Exchange (ETDEWEB)

    Frieden, Dorian; Tuerk, Andreas; Steiner, Daniel

    2013-07-15

    This working paper discusses similarities and differences between the cooperation mechanisms of the EU renewable energy directive (RES directive) and the flexible mechanisms of the Kyoto Protocol. The cooperation mechanisms allow the (virtual) trade of renewable energy and were introduced with the RES directive to provide Member States (MS) with greater flexibility to achieve their national targets for renewable energy sources (RES). A similar kind of flexibility is known from the flexible mechanisms of the Kyoto Protocol which aim at the cost efficient achievement of emission reduction targets. Lessons learned from the Kyoto mechanisms may allow conclusions to be drawn on the design and implementation of the renewable energy cooperation mechanisms. This paper first gives an overview of the cooperation mechanisms regarding their potential, advantages and disadvantages, barriers and preconditions. This is followed by a brief explanation of and a systematic comparison with the flexible mechanisms of the Kyoto Protocol – Joint Implementation (JI); Clean Development Mechanism (CDM); and International Emissions Trading (IET). A gamut of factors influenced the success of the Kyoto mechanisms in general and in specific national contexts. Therefore, it is not possible to directly transfer past experiences with the Kyoto mechanisms to the capability of specific nations to make use of the renewable energy cooperation mechanisms. A comparison of specific features, such as the mechanism type (transfer, project-based, support scheme), price building and specific barriers can, however, help anticipate the possible dynamics and challenges of the cooperation mechanisms. Experiences with the Kyoto mechanisms show that predictions based on supply-demand analysis were valid only to a limited extent and that specific factors such as institutional capacity constraints or legal uncertainties delayed or prevented the use of the mechanisms in some cases. Similarly, for the cooperation

  19. Degradation Mechanism in a Direct Carbon Fuel Cell Operated with Demineralised Brown Coal

    International Nuclear Information System (INIS)

    Rady, Adam C.; Giddey, Sarbjit; Kulkarni, Aniruddha; Badwal, Sukhvinder P.S.; Bhattacharya, Sankar

    2014-01-01

    Graphical abstract: - Highlights: • Degradation mechanism studied for demineralised coal in a direct carbon fuel cell. • Diffusion limited processes dominate the electrode polarisation losses in pure N 2 . • Major fuel cell performance loss occurred due to loss of carbon/anode contacts. • The anode retained its phase structure with minor other phases formed in operation. - Abstract: The performance of a demineralised and devolatilised coal from the Morwell mine in the Latrobe Valley, Victoria, has been investigated in a direct carbon fuel cell (DCFC) operated at 850 °C. The focus of the investigation has been on understanding degradation issues as a function of time involving a sequence of electrochemical impedance spectroscopy and voltage-current characteristic. Diffusion limited processes dominate the electrode polarisation losses in pure N 2 atmosphere, however, these decrease substantially in the presence of CO 2 as the anode chamber purge gas, due to in situ generation of fuel species by the reaction of CO 2 with carbon. Post-mortem analysis of anode by SEM and XRD revealed only a minor degradation due to its reduction, particle agglomeration as well as the formation of small quantity of new phases. However, major fuel cell performance degradation (increase of ohmic resistive and electrode polarisation losses) occurred due to loss of carbon/anode contacts and a reduction in the electron-conducting pathways as the fuel was consumed. The investigations revealed that the demineralised coal char can be used as a viable fuel for DCFC, however, further developments on anode materials and fuel feed mechanism would be required to achieve long-term sustained performance

  20. Hot Press as a Sustainable Direct Recycling Technique of Aluminium: Mechanical Properties and Surface Integrity.

    Science.gov (United States)

    Yusuf, Nur Kamilah; Lajis, Mohd Amri; Ahmad, Azlan

    2017-08-03

    Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (T s = 430, 480, and 530 °C) and holding times (t s = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at T s = 530 °C and t s = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices.

  1. Mechanics of Student-Directed Multi-University Internet Video-Conferencing Course

    Science.gov (United States)

    Durant, A. J.; Mann, C. P.; Rose, W. I.; Stix, J.

    2007-12-01

    Connecting graduate students with experts in a given discipline is vital to their success but has often been challenging because of logistics, costs, and scheduling. Advances in Internet video-conferencing now allow multiple parties to meet simultaneously in a virtual classroom environment. Here we describe the mechanics of a recent student-directed graduate-level course that enabled students to directly engage in scientific discussion with experts. Conducted under the auspices of the Earth Hazards (EHaz) Consortium, the spring 2007 Volcano Instability course connected nine previously disparate groups over North America in a combined learning and cultural experience. Each week course participants (including the guest speaker, students and university professors) reviewed current journal articles and a speaker presentation, and used Marratech Internet video- conferencing software to meet online and discuss the material with an expert on the subject. Internet video-conferencing provides an inexpensive and innovative approach to teaching across international boundaries. The EHaz 2007 Volcano Instability course connected 14 experts with 64 students and professors. Many universities can participate through this approach, allowing an advanced graduate class that normally contains 4 - 8 students on one campus to become a class of 50 or more dispersed over many campuses. As evidenced by overwhelmingly positive course evaluations, the approach was stimulating and conducive to learning, and has great potential for application over many other disciplines. This dynamic interaction between students and experts will ultimately raise the standard of instruction and motivate students to self-guide their learning experience to levels of greater understanding.

  2. Microstructures and mechanical properties of directionally solidified Ni-25%Si full lamellar in situ composites

    International Nuclear Information System (INIS)

    Zhang, Binggang; Li, Xiaopeng; Wang, Ting; Liu, Zheng

    2016-01-01

    Directional solidification experiments have been performed on Ni-25 at% Si alloy using electron beam floating zone method. A fully regular eutectic microstructures consisting of Ni, γ-Ni 31 Si 12 and β 1 -Ni 3 Si have been obtained. The influences of the directional solidification rate on the microstructures and properties of the full lamellar structures have been studied. The results show that the relationship between the mean interphase spacing (λ) and withdrawal rate (v) meets λ=29.9v −0.65 . The hardness increases with the increasing of growth rate (v) and decreasing of the interlamellar spacing (λ) which meets the relationship of H V =445.2v 0.14 and H V =910λ −0.21 . The maximum compressive strength, 2576 MPa, for DS samples is obtained by 10 mm/h. The average fracture toughness value found for 5 mm/h, 7 mm/h, 10 mm/h is 28.3 MPa m 1/2 , 29.1 MPa m 1/2 and 35.9 MPa m 1/2 , respectively. The crack bridging and crack deflection/interface debonding are the main toughening mechanism of Ni-25 at% Si with full lamellar structures.

  3. MPP1 directly interacts with flotillins in erythrocyte membrane - Possible mechanism of raft domain formation.

    Science.gov (United States)

    Biernatowska, Agnieszka; Augoff, Katarzyna; Podkalicka, Joanna; Tabaczar, Sabina; Gajdzik-Nowak, Weronika; Czogalla, Aleksander; Sikorski, Aleksander F

    2017-11-01

    Flotillins are prominent, oligomeric protein components of erythrocyte (RBC) membrane raft domains and are considered to play an important structural role in lateral organization of the plasma membrane. In our previous work on erythroid membranes and giant plasma membrane vesicles (GPMVs) derived from them we have shown that formation of functional domains (resting state rafts) depends on the presence of membrane palmitoylated protein 1 (MPP1/p55), pointing to its new physiological role. Exploration of the molecular mechanism of MPP1 function in organizing membrane domains described here, through searching for its molecular partners in RBC membrane by using different methods, led to the identification of the raft-marker proteins, flotillin 1 and flotillin 2, as hitherto unreported direct MPP1 binding-partners in the RBC membrane. These proteins are found in high molecular-weight complexes in native RBC membrane and, significantly, their presence was shown to be separate from the well-known protein 4.1-dependent interactions of MPP1 with membrane proteins. Furthermore, FLIM analysis revealed that loss of the endogenous MPP1-flotillins interactions resulted in significant changes in RBC membrane-fluidity, emphasizing the physiological importance of such interactions in vivo. Therefore, our data establish a new perspective on the role of MPP1 in erythroid cells and suggests that direct MPP1-flotillins interactions could be the major driving-force behind the formation of raft domains in RBC. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  4. The Synthesis of Nanostructured WC-Based Hardmetals Using Mechanical Alloying and Their Direct Consolidation

    Directory of Open Access Journals (Sweden)

    N. Al-Aqeeli

    2014-01-01

    Full Text Available Tungsten carbide- (WC- based hardmetals or cemented carbides represent an important class of materials used in a wide range of industrial applications which primarily include cutting/drilling tools and wear resistant components. The introduction and processing of nanostructured WC-based cemented carbides and their subsequent consolidation to produce dense components have been the subject of several investigations. One of the attractive means of producing this class of materials is by mechanical alloying technique. However, one of the challenging issues in obtaining the right end-product is the possible loss of the nanocrystallite sizes due to the undesirable grain growth during powder sintering step. Many research groups have engaged in multiple projects aiming at exploring the right path of consolidating the nanostructured WC-based powders without substantially loosing the attained nanostructure. The present paper highlights some key issues related to powder synthesis and sintering of WC-based nanostructured materials using mechanical alloying. The path of directly consolidating the powders using nonconventional consolidation techniques will be addressed and some light will be shed on the advantageous use of such techniques. Cobalt-bonded hardmetals will be principally covered in this work along with an additional exposure of the use of other binders in the WC-based hardmetals.

  5. Epicardial fat and atrial fibrillation: current evidence, potential mechanisms, clinical implications, and future directions.

    Science.gov (United States)

    Wong, Christopher X; Ganesan, Anand N; Selvanayagam, Joseph B

    2017-05-01

    Obesity is increasingly recognized as a major modifiable determinant of atrial fibrillation (AF). Although body mass index and other clinical measures are useful indications of general adiposity, much recent interest has focused on epicardial fat, a distinct adipose tissue depot that can be readily assessed using non-invasive imaging techniques. A growing body of data from epidemiological and clinical studies has demonstrated that epicardial fat is consistently associated with the presence, severity, and recurrence of AF across a range of clinical settings. Evidence from basic science and translational studies has also suggested that arrhythmogenic mechanisms may involve adipocyte infiltration, pro-fibrotic, and pro-inflammatory paracrine effects, oxidative stress, and other pathways. Despite these advances, however, significant uncertainty exists and many questions remain unanswered. In this article, we review our present understanding of epicardial fat, including its classification and quantification, existing evidence implicating its role in AF, potential mechanisms, implications for clinicians, and future directions for research. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  6. Direct visualization of glutamate transporter elevator mechanism by high-speed AFM.

    Science.gov (United States)

    Ruan, Yi; Miyagi, Atsushi; Wang, Xiaoyu; Chami, Mohamed; Boudker, Olga; Scheuring, Simon

    2017-02-14

    Glutamate transporters are essential for recovery of the neurotransmitter glutamate from the synaptic cleft. Crystal structures in the outward- and inward-facing conformations of a glutamate transporter homolog from archaebacterium Pyrococcus horikoshii , sodium/aspartate symporter Glt Ph , suggested the molecular basis of the transporter cycle. However, dynamic studies of the transport mechanism have been sparse and indirect. Here we present high-speed atomic force microscopy (HS-AFM) observations of membrane-reconstituted Glt Ph at work. HS-AFM movies provide unprecedented real-space and real-time visualization of the transport dynamics. Our results show transport mediated by large amplitude 1.85-nm "elevator" movements of the transport domains consistent with previous crystallographic and spectroscopic studies. Elevator dynamics occur in the absence and presence of sodium ions and aspartate, but stall in sodium alone, providing a direct visualization of the ion and substrate symport mechanism. We show unambiguously that individual protomers within the trimeric transporter function fully independently.

  7. Mechanism of enhanced performance on a hybrid direct carbon fuel cell using sawdust biofuels

    Science.gov (United States)

    Li, Shuangbin; Jiang, Cairong; Liu, Juan; Tao, Haoliang; Meng, Xie; Connor, Paul; Hui, Jianing; Wang, Shaorong; Ma, Jianjun; Irvine, John T. S.

    2018-04-01

    Biomass is expected to play a significant role in power generation in the near future. With the uprising of carbon fuel cells, hybrid direct carbon fuel cells (HDCFCs) show its intrinsic and incomparable advantages in the generation of clean energy with higher efficiency. In this study, two types of biomass treated by physical sieve and pyrolysis from raw sawdust are investigated on an anode-supported HDCFC. The structure and thermal analysis indicate that raw sawdust has well-formed cellulose I phase with very low ash. Electrochemical performance behaviors for sieved and pyrolyzed sawdust combined with various weight ratios of carbonate are compared in N2 and CO2 purge gas. The results show that the power output of sieved sawdust with 789 mWcm-2 is superior to that of pyrolyzed sawdust in CO2 flowing, as well as in N2 flowing. The anode reaction mechanism for the discrepancy of two fuels is explained and the emphasis is also placed on the modified oxygen-reduction cycle mechanism of catalytic effects of Li2CO3 and K2CO3 salts in promoting cell performance.

  8. Comparative study of mechanical properties of direct core build-up materials

    Directory of Open Access Journals (Sweden)

    Girish Kumar

    2015-01-01

    Full Text Available Background and Objectives: The strength greatly influences the selection of core material because core must withstand forces due to mastication and para-function for many years. This study was conducted to evaluate certain mechanical properties of commonly used materials for direct core build-up, including visible light cured composite, polyacid modified composite, resin modified glass ionomer, high copper amalgam, and silver cermet cement. Materials and Methods: All the materials were manipulated according to the manufacturer′s recommendations and standard test specimens were prepared. A universal testing machine at different cross-head speed was used to determine all the four mechanical properties. Mean compressive strength, diametral tensile strength, flexural strength, and elastic modulus with standard deviations were calculated. Multiple comparisons of the materials were also done. Results: Considerable differences in compressive strength, diametral tensile strength, and flexural strength were observed. Visible light cured composite showed relatively high compressive strength, diametral tensile strength, and flexural strength compared with the other tested materials. Amalgam showed the highest value for elastic modulus. Silver cermet showed less value for all the properties except for elastic modulus. Conclusions: Strength is one of the most important criteria for selection of a core material. Stronger materials better resist deformation and fracture provide more equitable stress distribution, greater stability, and greater probability of clinical success.

  9. Direct hydride shift mechanism and stereoselectivity of P450nor confirmed by QM/MM calculations.

    Science.gov (United States)

    Krámos, Balázs; Menyhárd, Dóra K; Oláh, Julianna

    2012-01-19

    Nitric oxide reductase (P450(nor)) found in Fusarium oxysporum catalyzes the reduction of nitric oxide to N(2)O in a multistep process. The reducing agent, NADH, is bound in the distal pocket of the enzyme, and direct hydride transfer occurs from NADH to the nitric oxide bound heme enzyme, forming intermediate I. Here we studied the possibility of hydride transfer from NADH to both the nitrogen and oxygen of the heme-bound nitric oxide, using quantum chemical and combined quantum mechanics/molecular mechanics (QM/MM) calculations, on two different protein models, representing both possible stereochemistries, a syn- and an anti-NADH arrangement. All calculations clearly favor hydride transfer to the nitrogen of nitric oxide, and the QM-only barrier and kinetic isotope effects are good agreement with the experimental values of intermediate I formation. We obtained higher barriers in the QM/MM calculations for both pathways, but hydride transfer to the nitrogen of nitric oxide is still clearly favored. The barriers obtained for the syn, Pro-R conformation of NADH are lower and show significantly less variation than the barriers obtained in the case of anti conformation. The effect of basis set and wide range of functionals on the obtained results are also discussed.

  10. Direct comparison of coronary bare metal vs. drug-eluting stents: same platform, different mechanics?

    Science.gov (United States)

    Schmidt, Wolfram; Lanzer, Peter; Behrens, Peter; Brandt-Wunderlich, Christoph; Öner, Alper; Ince, Hüseyin; Schmitz, Klaus-Peter; Grabow, Niels

    2018-01-08

    Drug-eluting stents (DES) compared to bare metal stents (BMS) have shown superior clinical performance, but are considered less suitable in complex cases. Most studies do not distinguish between DES and BMS with respect to their mechanical performance. The objective was to obtain mechanical parameters for direct comparison of BMS and DES. In vitro bench tests evaluated crimped stent profiles, crossability in stenosis models, elastic recoil, bending stiffness (crimped and expanded), and scaffolding properties. The study included five pairs of BMS and DES each with the same stent platforms (all n = 5; PRO-Kinetic Energy, Orsiro: BIOTRONIK AG, Bülach, Switzerland; MULTI-LINK 8, XIENCE Xpedition: Abbott Vascular, Temecula, CA; REBEL Monorail, Promus PREMIER, Boston Scientific, Marlborough, MA; Integrity, Resolute Integrity, Medtronic, Minneapolis, MN; Kaname, Ultimaster: Terumo Corporation, Tokyo, Japan). Statistical analysis used pooled variance t tests for pairwise comparison of BMS with DES. Crimped profiles in BMS groups ranged from 0.97 ± 0.01 mm (PRO-Kinetic Energy) to 1.13 ± 0.01 mm (Kaname) and in DES groups from 1.02 ± 0.01 mm (Orsiro) to 1.13 ± 0.01 mm (Ultimaster). Crossability was best for low profile stent systems. Elastic recoil ranged from 4.07 ± 0.22% (Orsiro) to 5.87 ± 0.54% (REBEL Monorail) including both BMS and DES. The bending stiffness of crimped and expanded stents showed no systematic differences between BMS and DES neither did the scaffolding. Based on in vitro measurements BMS appear superior to DES in some aspects of mechanical performance, yet the differences are small and not class uniform. The data provide assistance in selecting the optimal system for treatment and assessment of new generations of bioresorbable scaffolds. not applicable.

  11. Pore structure and mechanical properties of directionally solidified porous aluminum alloys

    Directory of Open Access Journals (Sweden)

    Komissarchuk Olga

    2014-01-01

    Full Text Available Porous aluminum alloys produced by the metal-gas eutectic method or GASAR process need to be performed under a certain pressure of hydrogen, and to carry over melt to a tailor-made apparatus that ensures directional solidification. Hydrogen is driven out of the melt, and then the quasi-cylindrical pores normal to the solidification front are usually formed. In the research, the effects of processing parameters (saturation pressure, solidification pressure, temperature, and holding time on the pore structure and porosity of porous aluminum alloys were analyzed. The mechanical properties of Al-Mg alloys were studied by the compressive tests, and the advantages of the porous structure were indicated. By using the GASAR method, pure aluminum, Al-3wt.%Mg, Al-6wt.%Mg and Al-35wt.%Mg alloys with oriented pores have been successfully produced under processing conditions of varying gas pressure, and the relationship between the final pore structure and the solidification pressure, as well as the influences of Mg quantity on the pore size, porosity and mechanical properties of Al-Mg alloy were investigated. The results show that a higher pressure of solidification tends to yield smaller pores in aluminum and its alloys. In the case of Al-Mg alloys, it was proved that with the increasing of Mg amount, the mechanical properties of the alloys sharply deteriorate. However, since Al-3%Mg and Al-6wt.%Mg alloys are ductile metals, their porous samples have greater compressive strength than that of the dense samples due to the existence of pores. It gives the opportunity to use them in industry at the same conditions as dense alloys with savings in weight and material consumption.

  12. Structural and mechanical properties of diamond-like carbon films deposited by direct current magnetron sputtering

    International Nuclear Information System (INIS)

    Broitman, E.; Hellgren, N.; Czigany, Zs.; Twesten, R.D.; Luning, J.; Petrov, I.; Hultman, L.; Holloway, B.C.

    2003-01-01

    The microstructure, morphology, and mechanical properties of diamond-like carbon (DLC) films deposited by direct current magnetron sputtering were investigated for microelectromechanical systems applications. Film properties were found to vary markedly with the ion energy (E ion ) and ion-to-carbon flux ratio (J ion /J C ). Cross-sectional high-resolution transmission electron microscopy revealed an amorphous microstructure. However, the presence of nanometer-sized domains at E ion ∼85 eV was detected. Film stresses, σ, which were compressive in all cases, ranged from 0.5 to 3.5 GPa and depended on the flux ratio as well as ion energy. The hardness (H), Young's moduli (ε), and elastic recovery (R) increased with E ion to maximum values of H=27 GPa, ε=250 GPa, and R=68% at E ion =85 eV and J ion /J C =4.4. However, near edge x-ray absorption fine structure and electron energy-loss spectrum analysis showed that the sp 2 /sp 3 content of the films does not change with E ion or J ion /J C . The measured change in mechanical properties without a corresponding change in sp 2 /sp 3 ratio is not consistent with any previously published models. We suggest that, in the ranges 5 eV ≤E ion ≤85 eV and 1.1 ≤J ion /J C ≤6.8, the presence of defective graphite formed by subplanted C and Ar atoms has the dominant influence on the mechanical properties of DLC films

  13. Direct right ventricular puncture for hemodynamic evaluation of a mechanical tricuspid valve prosthesis: a new indication for an old procedure.

    Science.gov (United States)

    Gibson, M A; Carell, E S

    1997-11-01

    The advent of transvenous right heart catheterization has relegated direct transthoracic right ventricular puncture largely to the role of "interesting historical footnote." However, in the case of a right ventricle that is "protected" by a mechanical tricuspid valve prosthesis, direct right ventricular puncture represents a reasonable alternative for obtaining accurate hemodynamic information.

  14. Optimum ratio of main mechanized operations for direct-flow fertilizers introduction

    Directory of Open Access Journals (Sweden)

    V. P. Uvarov

    2016-01-01

    Full Text Available Use of transport and technological means is carried out according to the direct-flow scheme and includes stage-by-stage performance as the main standard-setting operations (fertilizers transportation, movement and their distribution across a field, and auxiliary (return from a field and loading of fertilizers. The method of comparison of main types of operations at fertilizers application is given. An estimation criterion is a ratio of cargo movements on a road and across a field, proportionality coefficient between movement of freight and a fertilizers distribution area across the field. These indicators depend on transportation distances and doses of fertilizers application, and also on technology factor that is freight moving frequency across the field. The last characteristic is taken as the optimized parameter. An extremum of this indicator was searched due to a classical method. Optimum values of estimated indicators with the accounting of a variation of a ratio of load capacity and operating width of technical means are received. Concrete combinations of transportation distances and doses of fertilizers application are specified. The authors defined conditions of effective use of tractor and perspective automobile transport and technological means. They recommended to use the automeans allowing to change operating width. Realization of the stated methodological approach will make it possible to select an optimum ratio of the mechanized operations at direct-flow fertilizers application, to exclude additional cargo movements across the field, to cut fuel consumption, to increase productivity. Productivity of transport and technological means increases by 2.0; 1.3 and 1.15 times respectively to length of furrow 3; 9 and 27 km at fertilizers application by a dose of 0.06 kg per sq.m.

  15. Biased Brownian motion mechanism for processivity and directionality of single-headed myosin-VI.

    Science.gov (United States)

    Iwaki, Mitsuhiro; Iwane, Atsuko Hikikoshi; Ikebe, Mitsuo; Yanagida, Toshio

    2008-01-01

    Conventional form to function as a vesicle transporter is not a 'single molecule' but a coordinated 'two molecules'. The coordinated two molecules make it complicated to reveal its mechanism. To overcome the difficulty, we adopted a single-headed myosin-VI as a model protein. Myosin-VI is an intracellular vesicle and organelle transporter that moves along actin filaments in a direction opposite to most other known myosin classes. The myosin-VI was expected to form a dimer to move processively along actin filaments with a hand-over-hand mechanism like other myosin organelle transporters. However, wild-type myosin-VI was demonstrated to be monomer and single-headed, casting doubt on its processivity. Using single molecule techniques, we show that green fluorescent protein (GFP)-fused single-headed myosin-VI does not move processively. However, when coupled to a 200 nm polystyrene bead (comparable to an intracellular vesicle in size) at a ratio of one head per bead, single-headed myosin-VI moves processively with large (40 nm) steps. Furthermore, we found that a single-headed myosin-VI-bead complex moved more processively in a high-viscous solution (40-fold higher than water) similar to cellular environment. Because diffusion of the bead is 60-fold slower than myosin-VI heads alone in water, we propose a model in which the bead acts as a diffusional anchor for the myosin-VI, enhancing the head's rebinding following detachment and supporting processive movement of the bead-monomer complex. This investigation will help us understand how molecular motors utilize Brownian motion in cells.

  16. A Lever Coupling Mechanism in Dual-Mass Micro-Gyroscopes for Improving the Shock Resistance along the Driving Direction

    Directory of Open Access Journals (Sweden)

    Yang Gao

    2017-04-01

    Full Text Available This paper presents the design and application of a lever coupling mechanism to improve the shock resistance of a dual-mass silicon micro-gyroscope with drive mode coupled along the driving direction without sacrificing the mechanical sensitivity. Firstly, the mechanical sensitivity and the shock response of the micro-gyroscope are theoretically analyzed. In the mechanical design, a novel lever coupling mechanism is proposed to change the modal order and to improve the frequency separation. The micro-gyroscope with the lever coupling mechanism optimizes the drive mode order, increasing the in-phase mode frequency to be much larger than the anti-phase one. Shock analysis results show that the micro-gyroscope structure with the designed lever coupling mechanism can notably reduce the magnitudes of the shock response and cut down the stress produced in the shock process compared with the traditional elastic coupled one. Simulations reveal that the shock resistance along the drive direction is greatly increased. Consequently, the lever coupling mechanism can change the gyroscope’s modal order and improve the frequency separation by structurally offering a higher stiffness difference ratio. The shock resistance along the driving direction is tremendously enhanced without loss of the mechanical sensitivity.

  17. MECHANICAL AND THERMO–MECHANICAL PROPERTIES OF BI-DIRECTIONAL AND SHORT CARBON FIBER REINFORCED EPOXY COMPOSITES

    Directory of Open Access Journals (Sweden)

    G. AGARWAL

    2014-10-01

    Full Text Available This paper based on bidirectional and short carbon fiber reinforced epoxy composites reports the effect of fiber loading on physical, mechanical and thermo-mechanical properties respectively. The five different fiber loading, i.e., 10wt. %, 20wt. %, 30wt. %, 40wt. % and 50wt. % were taken for evaluating the above said properties. The physical and mechanical properties, i.e., hardness, tensile strength, flexural strength, inter-laminar shear strength and impact strength are determined to represent the behaviour of composite structures with that of fiber loading. Thermo-mechanical properties of the material are measured with the help of Dynamic Mechanical Analyser to measure the damping capacity of the material that is used to reduce the vibrations. The effect of storage modulus, loss modulus and tan delta with temperature are determined. Finally, Cole–Cole analysis is performed on both bidirectional and short carbon fiber reinforced epoxy composites to distinguish the material properties of either homogeneous or heterogeneous materials. The results show that with the increase in fiber loading the mechanical properties of bidirectional carbon fiber reinforced epoxy composites increases as compared to short carbon fiber reinforced epoxy composites except in case of hardness, short carbon fiber reinforced composites shows better results. Similarly, as far as Loss modulus, storage modulus is concerned bidirectional carbon fiber shows better damping behaviour than short carbon fiber reinforced composites.

  18. Expanding the Enzyme Universe: Accessing Non-Natural Reactions by Mechanism-Guided Directed Evolution

    Science.gov (United States)

    Renata, Hans; Wang, Z. Jane

    2015-01-01

    High selectivities and exquisite control over reaction outcomes entice chemists to use biocatalysts in organic synthesis. However, many useful reactions are not accessible because they are not in nature’s known repertoire. We will use this review to outline an evolutionary approach to engineering enzymes to catalyze reactions not found in nature. We begin with examples of how nature has discovered new catalytic functions and how such evolutionary progressions have been recapitulated in the laboratory starting from extant enzymes. We then examine non-native enzyme activities that have been discovered and exploited for chemical synthesis, emphasizing reactions that do not have natural counterparts. The new functions have mechanistic parallels to the native reaction mechanisms that often manifest as catalytic promiscuity and the ability to convert from one function to the other with minimal mutation. We present examples of how non-natural activities have been improved by directed evolution, mimicking the process used by nature to create new catalysts. Examples of new enzyme functions include epoxide opening reactions with non-natural nucleophiles catalyzed by a laboratory-evolved halohydrin dehalogenase, cyclopropanation and other carbene transfer reactions catalyzed by cytochrome P450 variants, and non-natural modes of cyclization by a modified terpene synthase. Lastly, we describe discoveries of non-native catalytic functions that may provide future opportunities for expanding the enzyme universe. PMID:25649694

  19. SMAD7 directly converts human embryonic stem cells to telencephalic fate by a default mechanism

    Science.gov (United States)

    Ozair, Mohammad Zeeshan; Noggle, Scott; Warmflash, Aryeh; Krzyspiak, Joanna Ela; Brivanlou, Ali H.

    2013-01-01

    Human embryonic stem cells (hESCs) provide a valuable window into the dissection of the molecular circuitry underlying the early formation of the human forebrain. However, dissection of signaling events in forebrain development using current protocols is complicated by non-neural contamination and fluctuation of extrinsic influences. Here we show that SMAD7, a cell-intrinsic inhibitor of TGFβ signaling, is sufficient to directly convert pluripotent hESCs to an anterior neural fate. Time-course gene expression revealed down-regulation of MAPK components, and combining MEK1/2 inhibition with SMAD7-mediated TGFβ inhibition promoted telencephalic conversion. FGF-MEK and TGFβ-SMAD signaling maintain hESCs by promoting pluripotency genes and repressing neural genes. Our findings suggest that in the absence of these cues, pluripotent cells simply revert to a program of neural conversion. Hence the “primed” state of hESCs requires inhibition of the “default” state of neural fate acquisition. This has parallels in amphibians, suggesting an evolutionarily conserved mechanism. PMID:23034881

  20. Design and optimization of mechanically down-doped terahertz fiber directional couplers

    DEFF Research Database (Denmark)

    Bao, Hualong; Nielsen, Kristian; Rasmussen, Henrik K.

    2014-01-01

    We present a thorough practical design optimization of broadband low loss, terahertz (THz) photonic crystal fiber directional couplers in which the two cores are mechanically down-doped with a triangular array of air holes. A figure of merit taking both the 3-dB bandwidth and loss of the coupler...... into account, is used for optimization of the structure parameters, given by the diameter and pitch of the cladding (d and Λ) and of the core (dc and Λc) air-hole structure. The coupler with Λ = 498.7 μm, dc= 324.2 μm, Λc = 74.8 μm, and dc = 32.5 μm is found to have the best performance at a center frequency...... of 1THz, with a bandwidth of 0.25 THz and a total device loss of 9.2 dB. The robustness of the optimum coupler to structural changes is investigated. © 2014 Optical Society of America....

  1. Multiphase turbulence mechanisms identification from consistent analysis of direct numerical simulation data

    Directory of Open Access Journals (Sweden)

    Ben Magolan

    2017-09-01

    Full Text Available Direct Numerical Simulation (DNS serves as an irreplaceable tool to probe the complexities of multiphase flow and identify turbulent mechanisms that elude conventional experimental measurement techniques. The insights unlocked via its careful analysis can be used to guide the formulation and development of turbulence models used in multiphase computational fluid dynamics simulations of nuclear reactor applications. Here, we perform statistical analyses of DNS bubbly flow data generated by Bolotnov (Reτ = 400 and Lu–Tryggvason (Reτ = 150, examining single-point statistics of mean and turbulent liquid properties, turbulent kinetic energy budgets, and two-point correlations in space and time. Deformability of the bubble interface is shown to have a dramatic impact on the liquid turbulent stresses and energy budgets. A reduction in temporal and spatial correlations for the streamwise turbulent stress (uu is also observed at wall-normal distances of y+ = 15, y/δ = 0.5, and y/δ = 1.0. These observations motivate the need for adaptation of length and time scales for bubble-induced turbulence models and serve as guidelines for future analyses of DNS bubbly flow data.

  2. Micro-electro-mechanical systems (MEMS)-based micro-scale direct methanol fuel cell development

    International Nuclear Information System (INIS)

    Yao, S.-C.; Tang Xudong; Hsieh, C.-C.; Alyousef, Yousef; Vladimer, Michael; Fedder, Gary K.; Amon, Cristina H.

    2006-01-01

    This paper describes a high-power density, silicon-based micro-scale direct methanol fuel cell (DMFC), under development at Carnegie Mellon. Major issues in the DMFC design include the water management and energy-efficient micro fluidic sub-systems. The air flow and the methanol circulation are both at a natural draft, while a passive liquid-gas separator removes CO 2 from the methanol chamber. An effective approach for maximizing the DMFC energy density, pumping the excess water back to the anode, is illustrated. The proposed DMFC contains several unique features: a silicon wafer with arrays of etched holes selectively coated with a non-wetting agent for collecting water at the cathode; a silicon membrane micro pump for pumping the collected water back to the anode; and a passive liquid-gas separator for CO 2 removal. All of these silicon-based components are fabricated using micro-electro-mechanical systems (MEMS)-based processes on the same silicon wafer, so that interconnections are eliminated, and integration efforts as well as post-fabrication costs are both minimized. The resulting fuel cell has an overall size of one cubic inch, produces a net output of 10 mW, and has an energy density three to five times higher than that of current lithium-ion batteries

  3. The nesprin-cytoskeleton interface probed directly on single nuclei is a mechanically rich system.

    Science.gov (United States)

    Balikov, Daniel A; Brady, Sonia K; Ko, Ung Hyun; Shin, Jennifer H; de Pereda, Jose M; Sonnenberg, Arnoud; Sung, Hak-Joon; Lang, Matthew J

    2017-09-03

    The cytoskeleton provides structure and plays an important role in cellular function such as migration, resisting compression forces, and transport. The cytoskeleton also reacts to physical cues such as fluid shear stress or extracellular matrix remodeling by reorganizing filament associations, most commonly focal adhesions and cell-cell cadherin junctions. These mechanical stimuli can result in genome-level changes, and the physical connection of the cytoskeleton to the nucleus provides an optimal conduit for signal transduction by interfacing with nuclear envelope proteins, called nesprins, within the LINC (linker of the nucleus to the cytoskeleton) complex. Using single-molecule on single nuclei assays, we report that the interactions between the nucleus and the cytoskeleton, thought to be nesprin-cytoskeleton interactions, are highly sensitive to force magnitude and direction depending on whether cells are historically interfaced with the matrix or with cell aggregates. Application of ∼10-30 pN forces to these nesprin linkages yielded structural transitions, with a base transition size of 5-6 nm, which are speculated to be associated with partial unfoldings of the spectrin domains of the nesprins and/or structural changes of histones within the nucleus.

  4. Computational comparison of quantum-mechanical models for multistep direct reactions

    International Nuclear Information System (INIS)

    Koning, A.J.; Akkermans, J.M.

    1993-01-01

    We have carried out a computational comparison of all existing quantum-mechanical models for multistep direct (MSD) reactions. The various MSD models, including the so-called Feshbach-Kerman-Koonin, Tamura-Udagawa-Lenske and Nishioka-Yoshida-Weidenmueller models, have been implemented in a single computer system. All model calculations thus use the same set of parameters and the same numerical techniques; only one adjustable parameter is employed. The computational results have been compared with experimental energy spectra and angular distributions for several nuclear reactions, namely, 90 Zr(p,p') at 80 MeV, 209 Bi(p,p') at 62 MeV, and 93 Nb(n,n') at 25.7 MeV. In addition, the results have been compared with the Kalbach systematics and with semiclassical exciton model calculations. All quantum MSD models provide a good fit to the experimental data. In addition, they reproduce the systematics very well and are clearly better than semiclassical model calculations. We furthermore show that the calculated predictions do not differ very strongly between the various quantum MSD models, leading to the conclusion that the simplest MSD model (the Feshbach-Kerman-Koonin model) is adequate for the analysis of experimental data

  5. Anodal Transcranial Direct Current Stimulation Promotes Frontal Compensatory Mechanisms in Healthy Elderly Subjects.

    Science.gov (United States)

    Cespón, Jesús; Rodella, Claudia; Rossini, Paolo M; Miniussi, Carlo; Pellicciari, Maria C

    2017-01-01

    Recent studies have demonstrated that transcranial direct current stimulation (tDCS) is potentially useful to improve working memory. In the present study, young and elderly subjects performed a working memory task ( n -back task) during an electroencephalogram recording before and after receiving anodal, cathodal, and sham tDCS over the left dorsolateral prefrontal cortex (DLPFC). We investigated modulations of behavioral performance and electrophysiological correlates of working memory processes (frontal and parietal P300 event-related potentials). A strong tendency to modulated working memory performance was observed after the application of tDCS. In detail, young, but not elderly, subjects benefited from additional practice in the absence of real tDCS, as indicated by their more accurate responses after sham tDCS. The cathodal tDCS had no effect in any group of participants. Importantly, anodal tDCS improved accuracy in elderly. Moreover, increased accuracy after anodal tDCS was correlated with a larger frontal P300 amplitude. These findings suggest that, in elderly subjects, improved working memory after anodal tDCS applied over the left DLPFC may be related to the promotion of frontal compensatory mechanisms, which are related to attentional processes.

  6. Anodal Transcranial Direct Current Stimulation Promotes Frontal Compensatory Mechanisms in Healthy Elderly Subjects

    Directory of Open Access Journals (Sweden)

    Jesús Cespón

    2017-12-01

    Full Text Available Recent studies have demonstrated that transcranial direct current stimulation (tDCS is potentially useful to improve working memory. In the present study, young and elderly subjects performed a working memory task (n-back task during an electroencephalogram recording before and after receiving anodal, cathodal, and sham tDCS over the left dorsolateral prefrontal cortex (DLPFC. We investigated modulations of behavioral performance and electrophysiological correlates of working memory processes (frontal and parietal P300 event-related potentials. A strong tendency to modulated working memory performance was observed after the application of tDCS. In detail, young, but not elderly, subjects benefited from additional practice in the absence of real tDCS, as indicated by their more accurate responses after sham tDCS. The cathodal tDCS had no effect in any group of participants. Importantly, anodal tDCS improved accuracy in elderly. Moreover, increased accuracy after anodal tDCS was correlated with a larger frontal P300 amplitude. These findings suggest that, in elderly subjects, improved working memory after anodal tDCS applied over the left DLPFC may be related to the promotion of frontal compensatory mechanisms, which are related to attentional processes.

  7. Impact of a stay in the intensive care unit on the preparation of Advance Directives: Descriptive, exploratory, qualitative study.

    Science.gov (United States)

    Andreu, Pascal; Dargent, Auguste; Large, Audrey; Meunier-Beillard, Nicolas; Vinault, Sandrine; Leiva-Rojas, Uriel; Ecarnot, Fiona; Prin, Sébastien; Charles, Pierre-Emmanuel; Fournel, Isabelle; Rigaud, Jean-Philippe; Quenot, Jean-Pierre

    2018-04-01

    Our objective was to assess, through a qualitative, exploratory study, the thought processes of patients regarding the formulation of advance directives (AD) after a stay in the ICU. The study was conducted from May to July 2016 using telephone interviews performed by four senior ICU physicians. Inclusion criteria were: patients discharged from ICU to home>3 months earlier. Semi-directive interviews with patients focused on 5 main points surrounding AD. In total, among 159 eligible patients, data from 94 (59%) were available for analysis. Among all those interviewed, 83.5% had never heard of "advance directives". Only 2% had executed AD before ICU admission, and 7% expressed a desire to prepare AD further to their ICU stay. Among the barriers to preparation of AD, lack of information was the main reason cited for not executing AD. Patients noted the following in their AD: withdrawal of life-support in case of vegetative/minimally conscious state or when there is no longer any hope, in case of uncontrollable pain, and if impossible to wean from mechanical ventilation. The ideal time to engage patients in these discussions is most likely well before an acute health event occurs, although this warrants further investigation both before and after ICU admissions. Copyright © 2017 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.

  8. Goal-directed mechanisms that constrain retrieval predict subsequent memory for new "foil" information.

    Science.gov (United States)

    Vogelsang, David A; Bonnici, Heidi M; Bergström, Zara M; Ranganath, Charan; Simons, Jon S

    2016-08-01

    To remember a previous event, it is often helpful to use goal-directed control processes to constrain what comes to mind during retrieval. Behavioral studies have demonstrated that incidental learning of new "foil" words in a recognition test is superior if the participant is trying to remember studied items that were semantically encoded compared to items that were non-semantically encoded. Here, we applied subsequent memory analysis to fMRI data to understand the neural mechanisms underlying the "foil effect". Participants encoded information during deep semantic and shallow non-semantic tasks and were tested in a subsequent blocked memory task to examine how orienting retrieval towards different types of information influences the incidental encoding of new words presented as foils during the memory test phase. To assess memory for foils, participants performed a further surprise old/new recognition test involving foil words that were encountered during the previous memory test blocks as well as completely new words. Subsequent memory effects, distinguishing successful versus unsuccessful incidental encoding of foils, were observed in regions that included the left inferior frontal gyrus and posterior parietal cortex. The left inferior frontal gyrus exhibited disproportionately larger subsequent memory effects for semantic than non-semantic foils, and significant overlap in activity during semantic, but not non-semantic, initial encoding and foil encoding. The results suggest that orienting retrieval towards different types of foils involves re-implementing the neurocognitive processes that were involved during initial encoding. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Mechanical analysis of non-uniform bi-directional functionally graded intelligent micro-beams using modified couple stress theory

    Science.gov (United States)

    Bakhshi Khaniki, Hossein; Rajasekaran, Sundaramoorthy

    2018-05-01

    This study develops a comprehensive investigation on mechanical behavior of non-uniform bi-directional functionally graded beam sensors in the framework of modified couple stress theory. Material variation is modelled through both length and thickness directions using power-law, sigmoid and exponential functions. Moreover, beam is assumed with linear, exponential and parabolic cross-section variation through the length using power-law and sigmoid varying functions. Using these assumptions, a general model for microbeams is presented and formulated by employing Hamilton’s principle. Governing equations are solved using a mixed finite element method with Lagrangian interpolation technique, Gaussian quadrature method and Wilson’s Lagrangian multiplier method. It is shown that by using bi-directional functionally graded materials in nonuniform microbeams, mechanical behavior of such structures could be affected noticeably and scale parameter has a significant effect in changing the rigidity of nonuniform bi-directional functionally graded beams.

  10. Effect of fiber directionality on the static and dynamic mechanical properties of 3D SiCf/SiC composites

    International Nuclear Information System (INIS)

    Hou, Zhenhua; Luo, Ruiying; Yang, Wei; Xu, Huaizhe; Han, Tao

    2016-01-01

    The static and dynamic mechanical properties of three-dimensional (3D) 4-directional and 3D 5-directional braided SiC f /SiC composites fabricated by polymer infiltration and pyrolysis (PIP) were investigated using static and dynamic bending tests, as well as microstructural characterization. X-ray diffraction revealed that polycarbosilane was converted into a matrix of crystalline β-SiC after PIP cycling. Test results indicated that the density, flexural strength, elastic modulus, fracture toughness, and storage modulus of 3D 5-directional SiC f /SiC composites were superior to those of 3D 4-directional braided SiC f /SiC composites; the former also showed a smaller internal friction than the latter. Results from Weibull statistical analysis indicated that the scale parameter σ 0 (736.9 MPa) and Weibull modulus m (21.7) of the 3D 5-directional specimen were higher than those of 3D 4-directional braided SiC f /SiC composites (629.6 MPa, 14.7). Both 3D braided composites demonstrated good toughness and avoided catastrophic brittle fractures under loading because of the effective crack energy dissipating mechanisms of crack deflection, interface debonding, and fiber pull-out. The internal friction and storage modulus of the 3D braided composites were sensitive to temperature. The cross angle of fiber placement in the preform and the direction of the applied force, as well as the pre-crack propagation remarkably influenced the static mechanical properties and failure behavior of the 3D braided SiC f /SiC composites. The dynamic mechanical properties of the 3D braided composites, including internal friction and storage modulus, were also considerably affected by fiber directionality in their preforms.

  11. Energy implications of mechanical and mechanical–biological treatment compared to direct waste-to-energy

    Energy Technology Data Exchange (ETDEWEB)

    Cimpan, Ciprian, E-mail: cic@kbm.sdu.dk; Wenzel, Henrik

    2013-07-15

    Highlights: • Compared systems achieve primary energy savings between 34 and 140 MJ{sub primary}/100 MJ{sub input} {sub waste.} • Savings magnitude is foremost determined by chosen primary energy and materials production. • Energy consumption and process losses can be upset by increased technology efficiency. • Material recovery accounts for significant shares of primary energy savings. • Direct waste-to-energy is highly efficient if cogeneration (CHP) is possible. - Abstract: Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical–biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation). The systems achieved net primary energy savings in a range between 34 and 140 MJ{sub primary}/100 MJ{sub input} {sub waste}, in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3–9.5%, 1–18% and 1–8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat

  12. Energy implications of mechanical and mechanical–biological treatment compared to direct waste-to-energy

    International Nuclear Information System (INIS)

    Cimpan, Ciprian; Wenzel, Henrik

    2013-01-01

    Highlights: • Compared systems achieve primary energy savings between 34 and 140 MJ primary /100 MJ input waste. • Savings magnitude is foremost determined by chosen primary energy and materials production. • Energy consumption and process losses can be upset by increased technology efficiency. • Material recovery accounts for significant shares of primary energy savings. • Direct waste-to-energy is highly efficient if cogeneration (CHP) is possible. - Abstract: Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical–biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation). The systems achieved net primary energy savings in a range between 34 and 140 MJ primary /100 MJ input waste , in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3–9.5%, 1–18% and 1–8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat recovery, the biodrying MBS

  13. Thermo-mechanical characterization of epoxy nanocomposites with different carbon nanotube distributions obtained by solvent aided and direct mixing.

    Directory of Open Access Journals (Sweden)

    M. Zarrelli

    2012-07-01

    Full Text Available Two different routes, namely solvent aided dispersion and direct mixing, were employed to disperse Multi-Walled Carbon Nanotubes (MWNTs into a mono-component epoxy system used as matrix for advanced composites. In the first route, MWCNTs were diluted in three different solvents (acetone, sodium dodecyl sulfate and ethanol and then mixed with the matrix by tip sonication. In the second case, carbonaceous nanoparticles were added directly into the hosting system and dispersion was carried out by using three different techniques (mechanical stirring, magnetic agitation and tip sonication. The effects of the solvents and agitation energy were investigated by optical microscopy at micron level, in order assess the more efficient dispersion procedure for the considered epoxy system. It was demonstrated that parameters associated with direct mixing rather than solvent solubility govern MWCNT dispersion. Optical analysis of the nanocomposite morphology evidenced a very low density of MWCNTs micron sized aggregates in the case of direct mixed tip sonicated samples if compared to those obtained by solution aided dispersion. In addition, nanocomposites obtained by sonication showed the lowest density of MWCNTs micron sized aggregates, also when compared with mechanically and magnetically stirred system. Dynamic Mechanical Analysis (DMA and Thermo-Mechanical Analysis (TMA results confirm the final result that among the considered direct mixing techniques, the direct tip sonication represents the most efficient route for MWCNT dispersion. Moreover, the mixing temperature of the hosting matrix system represents a fundamental feature in enhancing the MWCNT de-bundling and dispersion. Small X-ray Scattering analysis revealed that a nanosized structure of nanotubes is formed in the case of the tip sonicated samples that is heuristically correlated with both the maximum enhancement of mechanical modulus and the maximum reduction of thermal expansion coefficients.

  14. Book review: ALMOG, J. Referential Mechanics: Direct Reference and the Foundations of Semantics (Oxford University Press, 2014

    Directory of Open Access Journals (Sweden)

    Filipe Martone

    Full Text Available Abstract: In this review I discuss Joseph Almog's book "Referential Mechanics". The book discusses direct reference as conceived by three of its founding fathers, Kripke, Kaplan and Donnellan, and introduces Almog's ambitious project of providing a referential semantics to all subject-phrases. I offer a brief overview of its four chapters and point out some of their virtues and shortcomings.

  15. Research on corrosion mechanism of suspension insulator steel foot of direct current system and measures for corrosion inhibition

    Science.gov (United States)

    Chen, He; Yang, Yueguang; Su, Guolei; Wang, Xiaoqing; Zhang, Hourong; Sun, Xiaoyu; Fan, Youping

    2017-09-01

    There are increasingly serious electrocorrosion phenomena on insulator hardware caused by direct current transmission due to the wide-range popularization of extra high voltage direct current transmission engineering in our country. Steel foot corrosion is the main corrosion for insulators on positive polarity side of transmission lines. On one hand, the corrosion leads to the tapering off of steel foot diameter, having a direct influence on mechanical property of insulators; on the other hand, in condition of corrosion on steel foot wrapped in porcelain ware, the volume of the corrosion product is at least 50% more than that of the original steel foot, leading to bursting of porcelain ware, threatening safe operation of transmission lines. Therefore, it is necessary to conduct research on the phenomenon and propose feasible measures for corrosion inhibition. Starting with the corrosion mechanism, this article proposes two measures for corrosion inhibition, and verifies the inhibition effect in laboratory conditions, providing reference for application in engineering.

  16. Tensor Arithmetic, Geometric and Mathematic Principles of Fluid Mechanics in Implementation of Direct Computational Experiments

    Directory of Open Access Journals (Sweden)

    Bogdanov Alexander

    2016-01-01

    Full Text Available The architecture of a digital computing system determines the technical foundation of a unified mathematical language for exact arithmetic-logical description of phenomena and laws of continuum mechanics for applications in fluid mechanics and theoretical physics. The deep parallelization of the computing processes results in functional programming at a new technological level, providing traceability of the computing processes with automatic application of multiscale hybrid circuits and adaptive mathematical models for the true reproduction of the fundamental laws of physics and continuum mechanics.

  17. Implementation of a Goal-Directed Mechanical Ventilation Order Set Driven by Respiratory Therapists Improves Compliance With Best Practices for Mechanical Ventilation.

    Science.gov (United States)

    Radosevich, Misty A; Wanta, Brendan T; Meyer, Todd J; Weber, Verlin W; Brown, Daniel R; Smischney, Nathan J; Diedrich, Daniel A

    2017-01-01

    Data regarding best practices for ventilator management strategies that improve outcomes in acute respiratory distress syndrome (ARDS) are readily available. However, little is known regarding processes to ensure compliance with these strategies. We developed a goal-directed mechanical ventilation order set that included physician-specified lung-protective ventilation and oxygenation goals to be implemented by respiratory therapists (RTs). We sought as a primary outcome to determine whether an RT-driven order set with predefined oxygenation and ventilation goals could be implemented and associated with improved adherence with best practice. We evaluated 1302 patients undergoing invasive mechanical ventilation (1693 separate episodes of invasive mechanical ventilation) prior to and after institution of a standardized, goal-directed mechanical ventilation order set using a controlled before-and-after study design. Patient-specific goals for oxygenation partial pressure of oxygen in arterial blood (Pao 2 ), ARDS Network [Net] positive end-expiratory pressure [PEEP]/fraction of inspired oxygen [Fio 2 ] table use) and ventilation (pH, partial pressure of carbon dioxide) were selected by prescribers and implemented by RTs. Compliance with the new mechanical ventilation order set was high: 88.2% compliance versus 3.8% before implementation of the order set ( P mechanical ventilation, intensive care unit (ICU) length of stay, and in-hospital or ICU mortality. A standardized best practice mechanical ventilation order set can be implemented by a multidisciplinary team and is associated with improved compliance to written orders and adherence to the ARDSNet PEEP/Fio 2 table.

  18. Determinations of directions of the mean stress field in Sichuan-Yunnan region from a number of focal mechanism solutions

    Science.gov (United States)

    Zhong, Ji-Mao; Cheng, Wan-Zheng

    2006-07-01

    Based on the spatial orientation and slip direction of the fault plane solutions, we present the expression of corresponding mechanical axis tensor in geographic coordinate system, and then put forward a method for calculating average mechanical axis tensor and its eigenvalues, which involves solving the corresponding eigenequation. The method for deducing mean stress field from T, B, and P axes parameters of a number of focal mechanism solutions has been verified by inverting data of mean stress fields in Fuyun region and in Tangshan region with fitting method of slip direction, and both results are consistent. To study regional average stress field, we need to choose a population of focal mechanism solutions of earthquakes in the massifs where there are significant tectonic structures. According to the focal mechanism solutions of 256 moderate-strong earthquakes occurred in 13 seismic zones of Sichuan-Yunnan region, the quantitative analysis results of stress tensor in each seismic zone have been given. The algorithm of such method is simple and convenient, which makes the method for analyzing tectonic stress field with large amount of focal mechanism solution data become quantified.

  19. Comorbidity between Type 2 Diabetes and Depression in the Adult Population: Directions of the Association and Its Possible Pathophysiological Mechanisms

    Directory of Open Access Journals (Sweden)

    Line Iden Berge

    2015-01-01

    Full Text Available Type 2 diabetes and depression are regarded as comorbid conditions, and three possible directions of the association between the diseases can underlie this observation of comorbidity. First, common etiology can increase a person’s risk of both diseases; second, persons with type 2 diabetes have increased prevalence or risk of future development of depression; or third, persons with depression have increased prevalence or risk of development of type 2 diabetes. This review gives an overview over possible pathophysiological mechanisms for each of the directions of the association between type 2 diabetes and depression and further discusses epigenetics as an additional, direction independent approach. We argue that unspecific pathophysiological mechanisms involved in the stress response might, at least to some extent, explain each of the directions of the association between type 2 diabetes and depression, while changes in brain structure and function among persons with diabetes and possible increased risk of development of type 2 diabetes after use of antidepressant agents could represent more disease specific mechanisms underlying the comorbidity.

  20. Hybrid direct carbon fuel cells and their reaction mechanisms - a review

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Kammer Hansen, Kent

    2014-01-01

    with carbon capture and storage (CCS) due to the high purity of CO2 emitted in the exhaust gas. Direct carbon (or coal) fuel cells (DCFCs) are directly fed with solid carbon to the anode chamber. The fuel cell converts the carbon at the anode and the oxygen at the cathode into electricity, heat and reaction......As coal is expected to continue to dominate power generation demands worldwide, it is advisable to pursue the development of more efficient coal power generation technologies. Fuel cells show a much higher fuel utilization efficiency, emit fewer pollutants (NOx, SOx), and are more easily combined...

  1. Elucidating Direct Photolysis Mechanisms of Different Dissociation Species of Norfloxacin in Water and Mg2+ Effects by Quantum Chemical Calculations.

    Science.gov (United States)

    Wang, Se; Wang, Zhuang

    2017-11-11

    The study of pollution due to combined antibiotics and metals is urgently needed. Photochemical processes are an important transformation pathway for antibiotics in the environment. The mechanisms underlying the effects of metal-ion complexation on the aquatic photochemical transformation of antibiotics in different dissociation forms are crucial problems in science, and beg solutions. Herein, we investigated the mechanisms of direct photolysis of norfloxacin (NOR) in different dissociation forms in water and metal ion Mg 2+ effects using quantum chemical calculations. Results show that different dissociation forms of NOR had different maximum electronic absorbance wavelengths (NOR 2+ direct photolysis pathways were de-ethylation (N7-C8 bond cleavage) and decarboxylation (C2-C5 bond cleavage). Furthermore, the presence of Mg 2+ changed the order of the wavelength at maximum electronic absorbance (NOR⁺-Mg 2+ direct photolysis of NOR⁰, NOR⁺, and NOR 2+ . The calculated TS results indicated that the presence of Mg 2+ increased E a for most direct photolysis pathways of NOR, while it decreased E a for some direct photolysis pathways such as the loss of the piperazine ring and the damage of the piperazine ring of NOR⁰ and the defluorination of NOR⁺.

  2. Finite element analysis of the effect of force directions on tooth movement in extraction space closure with miniscrew sliding mechanics.

    Science.gov (United States)

    Kojima, Yukio; Kawamura, Jun; Fukui, Hisao

    2012-10-01

    Miniscrews placed in bone have been used as orthodontic anchorage in extraction space closure with sliding mechanics. The movement patterns of the teeth depend on the force directions. To move the teeth in a desired pattern, the appropriate direction of force must be selected. The purpose of this article is to clarify the relationship between force directions and movement patterns. By using the finite element method, orthodontic movements were simulated based on the remodeling law of the alveolar bone. The power arm length and the miniscrew position were varied to change the force directions. When the power arm was lengthened, rotation of the entire maxillary dentition decreased. The posterior teeth were effective for preventing rotation of the anterior teeth through an archwire. In cases of a high position of a miniscrew, bodily tooth movement was almost achieved. The vertical component of the force produced intrusion or extrusion of the entire dentition. Within the limits of the method, the mechanical simulations demonstrated the effect of force direction on movement patterns. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  3. The direction of water transport on Mars: A possible pumping mechanism

    Science.gov (United States)

    James, P. B.

    1987-01-01

    It is suggested that an atmospheric pumping mechanism might be at work in which water is preferentially transported into the north by a mass outflow wind (due to sublimation from polar cap) that is stronger during southern spring than it is during northern spring. The mechanism is provided by the asymmetric seasonal temperature distribution produced by the eccentric martial orbit and by the associated seasonal asymmetry in the carbon dioxide cycle. The alternating condensation and sublimation of CO2 at the poles produces condensation winds which, in turn, contribute to the meridional transport of water vapor.

  4. Mechanisms for focusing mitotic spindle poles by minus end-directed motor proteins.

    Science.gov (United States)

    Goshima, Gohta; Nédélec, François; Vale, Ronald D

    2005-10-24

    During the formation of the metaphase spindle in animal somatic cells, kinetochore microtubule bundles (K fibers) are often disconnected from centrosomes, because they are released from centrosomes or directly generated from chromosomes. To create the tightly focused, diamond-shaped appearance of the bipolar spindle, K fibers need to be interconnected with centrosomal microtubules (C-MTs) by minus end-directed motor proteins. Here, we have characterized the roles of two minus end-directed motors, dynein and Ncd, in such processes in Drosophila S2 cells using RNA interference and high resolution microscopy. Even though these two motors have overlapping functions, we show that Ncd is primarily responsible for focusing K fibers, whereas dynein has a dominant function in transporting K fibers to the centrosomes. We also report a novel localization of Ncd to the growing tips of C-MTs, which we show is mediated by the plus end-tracking protein, EB1. Computer modeling of the K fiber focusing process suggests that the plus end localization of Ncd could facilitate the capture and transport of K fibers along C-MTs. From these results and simulations, we propose a model on how two minus end-directed motors cooperate to ensure spindle pole coalescence during mitosis.

  5. Oscillatory mechanisms of response conflict elicited by color and motion direction: : an individual differences approach

    NARCIS (Netherlands)

    Vissers, M.E.; Ridderinkhof, K.R.; Cohen, M.X.; Slagter, H.A.

    Goal-directed behavior requires control over automatic behavior, for example, when goal-irrelevant information from the environment captures an inappropriate response and conflicts with the correct, goal-relevant action. Neural oscillations in the theta band (∼6 Hz) measured at midfrontal electrodes

  6. Direct mechanics assessment of elastic symmetries and properties of trabecular bone architecture

    NARCIS (Netherlands)

    Rietbergen, van B.; Odgaard, A.; Kabel, J.; Huiskes, H.W.J.

    1996-01-01

    A method is presented to find orthotropic elastic symmetries and constants directly from the elastic coefficients in the overall stiffness matrix of trabecular bone test specimens. Contrary to earlier developed techniques, this method does not require pure orthotropic behavior or additional fabric

  7. Fibrous hyaluronic acid hydrogels that direct MSC chondrogenesis through mechanical and adhesive cues.

    Science.gov (United States)

    Kim, Iris L; Khetan, Sudhir; Baker, Brendon M; Chen, Christopher S; Burdick, Jason A

    2013-07-01

    Electrospinning has recently gained much interest due to its ability to form scaffolds that mimic the nanofibrous nature of the extracellular matrix, such as the size and depth-dependent alignment of collagen fibers within hyaline cartilage. While much progress has been made in developing bulk, isotropic hydrogels for tissue engineering and understanding how the microenvironment of such scaffolds affects cell response, these effects have not been extensively studied in a nanofibrous system. Here, we show that the mechanics (through intrafiber crosslink density) and adhesivity (through RGD density) of electrospun hyaluronic acid (HA) fibers significantly affect human mesenchymal stem cell (hMSC) interactions and gene expression. Specifically, hMSC spreading, proliferation, and focal adhesion formation were dependent on RGD density, but not on the range of fiber mechanics investigated. Moreover, traction-mediated fiber displacements generally increased with more adhesive fibers. The expression of chondrogenic markers, unlike trends in cell spreading and cytoskeletal organization, was influenced by both fiber mechanics and adhesivity, in which softer fibers and lower RGD densities generally enhanced chondrogenesis. This work not only reveals concurrent effects of mechanics and adhesivity in a fibrous context, but also highlights fibrous HA hydrogels as a promising scaffold for future cartilage repair strategies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Direct Visualization of Mechanical Beats by Means of an Oscillating Smartphone

    Science.gov (United States)

    Giménez, Marcos H.; Salinas, Isabel; Monsoriu, Juan A.; Castro-Palacio, Juan C.

    2017-01-01

    The resonance phenomenon is widely known in physics courses. Qualitatively speaking, resonance takes place in a driven oscillating system whenever the frequency approaches the natural frequency, resulting in maximal oscillatory amplitude. Very closely related to resonance is the phenomenon of mechanical beating, which occurs when the driving and…

  9. A Direct Derivation of the Equations of Motion for 3D-Flexible Mechanical Systems

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard; Pedersen, Mads Leergaard

    1998-01-01

    equations for flexible mechanical systems are derived using the principle of virtual work, which introduces inertia in a straightforward manner, because this principle treats inertia as a force. The flexible formulation is exemplified by the use of circular beam elements and some basic matrices are derived...

  10. Comparison of mechanisms for DNA strand break formation by the direct and indirect effect of radiation

    International Nuclear Information System (INIS)

    Schulte-Frohlinde, D.

    1986-01-01

    Irradiation of cells may lead to mutations, reproductive cell death and the disappearance of some or all cell activities. These effects, especially reproductive cell death, are believed to be the result of damage to DNA. Two kinds of formation of DNA damage are often distinguished, the so-called ''direct'' and the ''indirect'' effect of irradiation. The direct effect is due to ionization or electronic excitation of the DNA, and the indirect effect is caused by reactive species, in most cases free radicals, which are produced in the vicinity of the DNA. These radicals may be primary radicals produced by energy absorption in water, i.e., the solvated electron, the H-atom and the OH radical, or organic radicals produced from organic material other than DNA either by interaction with radiation or by reaction with the primary radicals generated from water. 36 refs., 2 figs., 2 tabs

  11. Carbon out-diffusion mechanism for direct graphene growth on a silicon surface

    International Nuclear Information System (INIS)

    Kim, Byung-Sung; Lee, Jong Woon; Jang, Yamujin; Choi, Soon Hyung; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Joo, Won-Jae; Hwang, Sungwoo; Whang, Dongmok

    2015-01-01

    Direct growth of graphene on silicon (Si) through chemical vapor deposition has predominantly focused on surface-mediated processes due to the low carbon (C) solubility in Si. However, a considerable quantity of C atoms was incorporated in Si and formed Si 1−x C x alloy with a reduced lattice dimension even in the initial stage of direct graphene growth. Subsequent high temperature annealing promoted active C out-diffusion, resulting in the formation of a graphitic layer on the Si surface. Furthermore, the significantly low thermal conductivity of the Si 1−x C x alloy shows that the incorporated C atoms affect the properties of a semiconductor adjacent to the graphene. These findings provide a key guideline for controlling desirable properties of graphene and designing hybrid semiconductor/graphene architectures for various applications

  12. Screw calciner mechanical direct denitration process for plutonium nitrate to oxide conversion

    International Nuclear Information System (INIS)

    Souply, K.R.; Sperry, W.E.

    1977-01-01

    This report describes a screw calciner direct-denitration process for converting plutonium nitrate to plutonium oxide. The information should be used when making comparisons of alternative plutonium nitrate-to-oxide conversion processes or as a basis for further detailed studies. The report contains process flow sheets with a material balance; a process description; and a discussion of the process including history, advantages and disadvantages, and additional research required

  13. Dual and Direction-Selective Mechanisms of Phosphate Transport by the Vesicular Glutamate Transporter

    Directory of Open Access Journals (Sweden)

    Julia Preobraschenski

    2018-04-01

    Full Text Available Summary: Vesicular glutamate transporters (VGLUTs fill synaptic vesicles with glutamate and are thus essential for glutamatergic neurotransmission. However, VGLUTs were originally discovered as members of a transporter subfamily specific for inorganic phosphate (Pi. It is still unclear how VGLUTs accommodate glutamate transport coupled to an electrochemical proton gradient ΔμH+ with inversely directed Pi transport coupled to the Na+ gradient and the membrane potential. Using both functional reconstitution and heterologous expression, we show that VGLUT transports glutamate and Pi using a single substrate binding site but different coupling to cation gradients. When facing the cytoplasm, both ions are transported into synaptic vesicles in a ΔμH+-dependent fashion, with glutamate preferred over Pi. When facing the extracellular space, Pi is transported in a Na+-coupled manner, with glutamate competing for binding but at lower affinity. We conclude that VGLUTs have dual functions in both vesicle transmitter loading and Pi homeostasis within glutamatergic neurons. : Preobraschenski et al. show that the vesicular glutamate transporter functions as a bi-directional phosphate transporter that is coupled with different cations in each direction and hence may play a key role in neuronal phosphate homeostasis. Keywords: VGLUT, SLC17 family, type I Na+-dependent inorganic phosphate transporter, ATPase, proteoliposomes, hybrid vesicles, anti-VGLUT1 nanobody

  14. Mechanisms of poliovirus inactivation by the direct and indirect effects of ionizing radiation

    International Nuclear Information System (INIS)

    Ward, R.L.

    1980-01-01

    This study was designed to measure the effects of ionizing radiation on poliovirus particles when given under conditions where either direct (in broth) or indirect (in water) effects were predominant. Under direct conditions, inactivation of poliovirus was found to be due primarily to RNA damage, although capsid damage could account for about one-third of the viral inactivation. RNA damage did not appear to be due to strand breakage and therefore was probably caused primarily by base damage or crosslink formation. Capsid damage under direct irradiation conditions did not result in significant alterations of either the sedimentation coefficients or the isoelectric points of the poliovirus particles or detectable modification of the sizes of the viral proteins. It did, however, cause loss of availability to bind to host cells. Under indirect conditions no more than 25% of viral inactivation appeared to be due to RNA damage. However, the sedimentation coefficients and isoelectric points of the viral particles were greatly altered, and their abilities to bind to cells were lost at about three-fourths the rate of loss of infectivity. Capsid damage in this case did result in changes in the sizes of capsid proteins. Therefore, the majority of the radiation inactivation under indirect conditions appeared to be due to protein damage

  15. Direct observation of toughening mechanisms in carbon nanotube ceramic matrix composites

    International Nuclear Information System (INIS)

    Xia, Z.; Riester, L.; Curtin, W.A.; Li, H.; Sheldon, B.W.; Liang, J.; Chang, B.; Xu, J.M.

    2004-01-01

    The excellent mechanical properties of carbon nanotubes (CNTS) are driving research into the creation of new strong, tough nanocomposite systems. Here, the first evidence of toughening mechanisms operating in carbon-nanotube-reinforced ceramic composites is presented. A highly ordered array of parallel multiwall CNTs in an alumina matrix was fabricated. Nanoindentation introduced controlled cracks and the damage was examined by scanning electron microscopy. These nanocomposites exhibit the three hallmarks of toughening found in micron-scale fiber composites: crack deflection at the CNT/matrix interface; crack bridging by CNTs; and CNT pullout on the fracture surfaces. Interface debonding and sliding can thus occur in materials with microstructures approaching the atomic scale. Furthermore, for certain geometries a new mechanism of nanotube collapse in 'shear bands' occurs, rather than crack formation, suggesting that these materials can have multiaxial damage tolerance. The quantitative indentation data and computational models are used to determine the multiwall CNT axial Young's modulus as 200-570 GPa, depending on the nanotube geometry and quality. Three-dimensional FEM analysis indicates that matrix residual stresses on the order of 300 MPa are sustained in these materials without spontaneous cracking, suggesting that residual stress can be used to engineer enhanced performance. These nanoscale ceramic composites thus have potential for toughening and damage tolerance at submicron scales, and so are excellent candidates for wear-resistant coatings

  16. Design and application of permanent magnet flux sources for mechanical testing of magnetoactive elastomers at variable field directions.

    Science.gov (United States)

    Hiptmair, F; Major, Z; Haßlacher, R; Hild, S

    2015-08-01

    Magnetoactive elastomers (MAEs) are a class of smart materials whose mechanical properties can be rapidly and reversibly changed by an external magnetic field. Due to this tunability, they are useable for actuators or in active vibration control applications. An extensive magnetomechanical characterization is necessary for MAE material development and requires experiments under cyclic loading in uniform but variable magnetic fields. MAE testing apparatus typically rely on fields of adjustable strength, but fixed (transverse) direction, often provided by electromagnets. In this work, two permanent magnet flux sources were developed as an add-on for a modular test stand, to allow for mechanical testing in uniform fields of variable direction. MAE specimens, based on a silicone matrix with isotropic and anisotropic carbonyl iron particle distributions, were subjected to dynamic mechanical analysis under different field and loading configurations. The magneto-induced increase of stiffness and energy dissipation was determined by the change of the hysteresis loop area and dynamic modulus values. A distinct influence of the composite microstructure and the loading state was observed. Due to the very soft and flexible matrix used for preparing the MAE samples, the material stiffness and damping behavior could be varied over a wide range via the applied field direction and intensity.

  17. Mechanisms governing the direct removal of wastes from the Waste Isolation Pilot Plant repository caused by exploratory drilling

    International Nuclear Information System (INIS)

    Berglund, J.W.

    1992-12-01

    Two processes are identified that can influence the quantity of wastes brought to the ground surface when a waste disposal room of the Waste Isolation Pilot Plant is inadvertently penetrated by an exploratory borehole. The first mechanism is due to the erosion of the borehole wall adjacent to the waste caused by the flowing drilling fluid (mud); a quantitative computational model based upon the flow characteristics of the drilling fluid (laminar or turbulent) and other drilling parameters is developed and example results shown. The second mechanism concerns the motion of the waste and borehole spall caused by the flow of waste-generated gas to the borehole. Some of the available literature concerning this process is discussed, and a number of elastic and elastic-plastic finite-difference and finite-element calculations are described that confirm the potential importance of this process in directly removing wastes from the repository to the ground surface. Based upon the amount of analysis performed to date, it is concluded that it is not unreasonable to expect that volumes of waste several times greater than that resulting from direct cutting of a gauge borehole could eventually reach the ground surface. No definitive quantitative model for waste removal as a result of the second mechanism is presented; it is concluded that decomposed waste constitutive data must be developed and additional experiments performed to assess further the full significance of this latter mechanism

  18. The direct heat measurement of mechanical energy storage metal-organic frameworks.

    Science.gov (United States)

    Rodriguez, Julien; Beurroies, Isabelle; Loiseau, Thierry; Denoyel, Renaud; Llewellyn, Philip L

    2015-04-07

    In any process, the heat exchanged is an essential property required in its development. Whilst the work related to structural transitions of some flexible metal-organic frameworks (MOFs) has been quantified and linked with potential applications such as molecular springs or shock absorbers, the heat related to such transitions has never been directly measured. This has now been carried out with MIL-53(Al) using specifically devised calorimetry experiments. We project the importance of these heats in devices such as molecular springs or dampers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Feedback control for distributed heat transfer mechanisms in direct-contact membrane distillation system

    KAUST Repository

    Eleiwi, Fadi; N'Doye, Ibrahima; Laleg-Kirati, Taous-Meriem

    2015-01-01

    In this paper, the problem of stabilization and production rate reference tracking for a Direct-Contact Membrane Distillation (DCMD) system is addressed. Sufficient conditions for the asymptotic and exponential stabilization for DCMD system are presented using the Gronwall-Bellman lemma and Linear Matrix Inequalities (LMIs) approaches, respectively. A nonlinear observer is then proposed to estimate the temperature distribution among the DCMD domain. This contributes to propose a reference production rate control design for the DCMD process via observer-based output control approach. Finally, numerical simulations are given to show the effectiveness of the proposed methods.

  20. Feedback control for distributed heat transfer mechanisms in direct-contact membrane distillation system

    KAUST Repository

    Eleiwi, Fadi

    2015-09-21

    In this paper, the problem of stabilization and production rate reference tracking for a Direct-Contact Membrane Distillation (DCMD) system is addressed. Sufficient conditions for the asymptotic and exponential stabilization for DCMD system are presented using the Gronwall-Bellman lemma and Linear Matrix Inequalities (LMIs) approaches, respectively. A nonlinear observer is then proposed to estimate the temperature distribution among the DCMD domain. This contributes to propose a reference production rate control design for the DCMD process via observer-based output control approach. Finally, numerical simulations are given to show the effectiveness of the proposed methods.

  1. Dynamic analysis of propulsion mechanism directly driven by wave energy for marine mobile buoy

    Science.gov (United States)

    Yu, Zhenjiang; Zheng, Zhongqiang; Yang, Xiaoguang; Chang, Zongyu

    2016-07-01

    Marine mobile buoy(MMB) have many potential applications in the maritime industry and ocean science. Great progress has been made, however the technology in this area is far from maturity in theory and faced with many difficulties in application. A dynamic model of the propulsion mechanism is very necessary for optimizing the parameters of the MMB, especially with consideration of hydrodynamic force. The principle of wave-driven propulsion mechanism is briefly introduced. To set a theory foundation for study on the MMB, a dynamic model of the propulsion mechanism of the MMB is obtained. The responses of the motion of the platform and the hydrofoil are obtained by using a numerical integration method to solve the ordinary differential equations. A simplified form of the motion equations is reached by omitting terms with high order small values. The relationship among the heave motion of the buoy, stiffness of the elastic components, and the forward speed can be obtained by using these simplified equations. The dynamic analysis show the following: The angle of displacement of foil is fairly small with the biggest value around 0.3 rad; The speed of mobile buoy and the angle of hydrofoil increased gradually with the increase of heave motion of buoy; The relationship among heaven motion, stiffness and attack angle is that heave motion leads to the angle change of foil whereas the item of speed or push function is determined by vertical velocity and angle, therefore, the heave motion and stiffness can affect the motion of buoy significantly if the size of hydrofoil is kept constant. The proposed model is provided to optimize the parameters of the MMB and a foundation is laid for improving the performance of the MMB.

  2. Quantification of mechanical ventricular dyssynchrony. Direct comparison of velocity-encoded and cine magnetic resonance imaging

    International Nuclear Information System (INIS)

    Muellerleile, K.; Baholli, L.; Groth, M.

    2011-01-01

    Purpose: The preoperative assessment of mechanical dyssynchrony can help to improve patient selection in candidates for cardiac resynchronization therapy (CRT). The present study compared the performance of velocity-encoded (VENC) MRI to cine-magnetic resonance imaging (MRI) for quantifying mechanical ventricular dyssynchrony. Materials and Methods: VENC-MRI and cine-MRI were performed in 20 patients with heart failure NYHA class III and reduced ejection fraction (median: 24 %, interquartile range: 18 - 28 %) before CRT device implantation. The interventricular mechanical delay (IVMD) was assessed by VENC-MRI as the temporal difference between the onset of aortic and pulmonary flow. Intraventricular dyssynchrony was quantified by cine-MRI, using the standard deviation of time to maximal wall thickening in sixteen left ventricular segments (SDt-16). The response to CRT was assessed in a six-month follow-up. Results: 14 patients (70 %) clinically responded to CRT. A similar accuracy was found to predict the response to CRT by measurements of the IVMD and SDt-16 (75 vs. 70 %; p = ns). The time needed for data analysis was significantly shorter for the IVMD at 1.69 min (interquartile range: 1.66 - 1.88 min) compared to 9.63 min (interquartile range: 8.92 - 11.63 min) for the SDt-16 (p < 0.0001). Conclusion: Measurements of the IVMD by VENC-MRI and the SDt-16 by cine-MRI provide a similar accuracy to identify clinical responders to CRT. However, data analysis of the IVMD is significantly less time-consuming compared to data analysis of the SDt-16. (orig.)

  3. Controlled drilling technology for HLW management. Directional drilling and mechanics/stress measurements in the borehole

    International Nuclear Information System (INIS)

    Kiho, Kenzo; Shin, Koichi; Okada, Tetsuji; Obuchi, Yasuyoshi; Sunaga, Takayuki; Hase, Kazunori

    2013-01-01

    Since 2000, Central Research Institute of Electric Power Industry (CRIEPI) has been conducting the project on controlled drilling and the logging/measurement technologies in its boreholes. Especially borehole pressure meter and bore hole stress measurement apparatus which can apply to the controlled drilling system was developed. The bore hole was drilled to the 1000 m long in order to intersect the Omagari fault located at Horonobe town in Hokkaido and its core recovery was 99.8% as of FY. 2011. Using borehole logging/measurement/survey, the geological, hydrological, geo-mechanical, geophysical and geochemical data were collected and the Omagari fault was characterized. (author)

  4. Distinct Mechanisms of Nuclease-Directed DNA-Structure-Induced Genetic Instability in Cancer Genomes.

    Science.gov (United States)

    Zhao, Junhua; Wang, Guliang; Del Mundo, Imee M; McKinney, Jennifer A; Lu, Xiuli; Bacolla, Albino; Boulware, Stephen B; Zhang, Changsheng; Zhang, Haihua; Ren, Pengyu; Freudenreich, Catherine H; Vasquez, Karen M

    2018-01-30

    Sequences with the capacity to adopt alternative DNA structures have been implicated in cancer etiology; however, the mechanisms are unclear. For example, H-DNA-forming sequences within oncogenes have been shown to stimulate genetic instability in mammals. Here, we report that H-DNA-forming sequences are enriched at translocation breakpoints in human cancer genomes, further implicating them in cancer etiology. H-DNA-induced mutations were suppressed in human cells deficient in the nucleotide excision repair nucleases, ERCC1-XPF and XPG, but were stimulated in cells deficient in FEN1, a replication-related endonuclease. Further, we found that these nucleases cleaved H-DNA conformations, and the interactions of modeled H-DNA with ERCC1-XPF, XPG, and FEN1 proteins were explored at the sub-molecular level. The results suggest mechanisms of genetic instability triggered by H-DNA through distinct structure-specific, cleavage-based replication-independent and replication-dependent pathways, providing critical evidence for a role of the DNA structure itself in the etiology of cancer and other human diseases. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  5. Effect of direct quenching on the microstructure and mechanical properties of the lean-chemistry HSLA-100 steel plates

    International Nuclear Information System (INIS)

    Dhua, S.K.; Sen, S.K.

    2011-01-01

    Highlights: → Direct-quenched and tempered (DQT) steels gives better mechanical properties. → Fine Cu and Nb (C, N) precipitates enhance matrix strengthening and tempering resistance. → Boron promotes hardenability, but low temperature Charpy impact toughness gets affected. → Mechanical properties equivalent to HSLA-100 steel is achieved by directly quenched leaner chemistry alloys. - Abstract: The influence of direct quenching on structure-property behavior of lean chemistry HSLA-100 steels was studied. Two laboratory heats, one containing Cu and Nb (C:0.052, Mn:0.99, Cu:1.08, Nb:0.043, Cr:0.57, Ni:1.76, Mo:0.55 pct) and the other containing Cu, Nb and B (C:0.04, Mn:1.02, Cu:1.06, Nb:0.036, Cr:0.87, Ni:1.32, Mo:0.41, B:0.002 percent) were hot-rolled into 25 and 12.5 mm thick plates by varying finish-rolling temperatures. The plates were heat-treated by conventional reheat quenching and tempering (RQT), as well as by direct quenching and tempering (DQT) techniques. In general, direct-quench and tempered plates of Nb-Cu heat exhibited good strength (yield strength ∼ 900 MPa) and low-temperature impact toughness (average: 74 J at -85 deg. C); the Charpy V-notch impact energies were marginally lower than conventional HSLA-100 steel. In Nb-Cu-B heat, impact toughness at low-temperature was inferior owing to boron segregation at grain boundaries. Transmission electron microscopy (TEM) and scanning auger microprobe (SAM) analysis confirmed existence of borocarbides at grain boundaries in this steel. In general, for both the steels, the mechanical properties of the direct-quench and tempered plates were found to be superior to reheat quench and tempered plates. A detailed transmission electron microscopy study revealed presence of fine Cu and Nb (C, N) precipitates in these steels. It was also observed that smaller martensite inter-lath spacing, finer grains and precipitates in direct-quench and tempered plates compared to the reheat quench and tempered plates

  6. Direct binding of ledipasvir to HCV NS5A: mechanism of resistance to an HCV antiviral agent.

    Directory of Open Access Journals (Sweden)

    Hyock Joo Kwon

    Full Text Available Ledipasvir, a direct acting antiviral agent (DAA targeting the Hepatitis C Virus NS5A protein, exhibits picomolar activity in replicon cells. While its mechanism of action is unclear, mutations that confer resistance to ledipasvir in HCV replicon cells are located in NS5A, suggesting that NS5A is the direct target of ledipasvir. To date co-precipitation and cross-linking experiments in replicon or NS5A transfected cells have not conclusively shown a direct, specific interaction between NS5A and ledipasvir. Using recombinant, full length NS5A, we show that ledipasvir binds directly, with high affinity and specificity, to NS5A. Ledipasvir binding to recombinant NS5A is saturable with a dissociation constant in the low nanomolar range. A mutant form of NS5A (Y93H that confers resistance to ledipasvir shows diminished binding to ledipasvir. The current study shows that ledipasvir inhibits NS5A through direct binding and that resistance to ledipasvir is the result of a reduction in binding affinity to NS5A mutants.

  7. Optimization of mechanical strength of titania fibers fabricated by direct drawing

    Science.gov (United States)

    Hanschmidt, Kelli; Tätte, Tanel; Hussainova, Irina; Part, Marko; Mändar, Hugo; Roosalu, Kaspar; Chasiotis, Ioannis

    2013-11-01

    Nanostructured polycrystalline titania (TiO2) microfibers were produced by direct drawing from visco-elastic alkoxide precursors. The fiber crystallinity and grain size were shown to depend on post-treatment calcination temperature. Tensile tests with individual fibers showed strong sensitivity of the elastic modulus and the tensile strength to microstructural details of the fibers. The elastic modulus of as-fabricated fibers increased about 10 times after calcination at 700 ∘C, while the strain at failure remained almost the same at ˜1.4 %. The highest tensile strength of more than 800 MPa was exhibited by nanoscale grained fibers with a bimodal grain size distribution consisting of rutile grains embedded into an anatase matrix. This structure is believed to have reduced the critical defect size, and thus increased the tensile strength. The resultant fibers showed properties that were appropriate for reinforcement of different matrixes.

  8. Expanding the enzyme universe: accessing non-natural reactions by mechanism-guided directed evolution.

    Science.gov (United States)

    Renata, Hans; Wang, Z Jane; Arnold, Frances H

    2015-03-09

    High selectivity and exquisite control over the outcome of reactions entice chemists to use biocatalysts in organic synthesis. However, many useful reactions are not accessible because they are not in nature's known repertoire. In this Review, we outline an evolutionary approach to engineering enzymes to catalyze reactions not found in nature. We begin with examples of how nature has discovered new catalytic functions and how such evolutionary progression has been recapitulated in the laboratory starting from extant enzymes. We then examine non-native enzyme activities that have been exploited for chemical synthesis, with an emphasis on reactions that do not have natural counterparts. Non-natural activities can be improved by directed evolution, thus mimicking the process used by nature to create new catalysts. Finally, we describe the discovery of non-native catalytic functions that may provide future opportunities for the expansion of the enzyme universe. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Direct path from microscopic mechanics to Debye shielding, Landau damping and wave-particle interaction

    International Nuclear Information System (INIS)

    Escande, D F; Elskens, Yves; Doveil, F

    2015-01-01

    The derivation of Debye shielding and Landau damping from the N-body description of plasmas is performed directly by using Newton’s second law for the N-body system. This is done in a few steps with elementary calculations using standard tools of calculus and no probabilistic setting. Unexpectedly, Debye shielding is encountered together with Landau damping. This approach is shown to be justified in the one-dimensional case when the number of particles in a Debye sphere becomes large. The theory is extended to accommodate a correct description of trapping and chaos due to Langmuir waves. On top of their well-known production of collisional transport, the repulsive deflections of electrons are shown to produce shielding, in such a way that each particle is shielded by all other ones, while keeping in uninterrupted motion. (paper)

  10. Malfunction of cardiac devices after radiotherapy without direct exposure to ionizing radiation: mechanisms and experimental data.

    Science.gov (United States)

    Zecchin, Massimo; Morea, Gaetano; Severgnini, Mara; Sergi, Elisabetta; Baratto Roldan, Anna; Bianco, Elisabetta; Magnani, Silvia; De Luca, Antonio; Zorzin Fantasia, Anna; Salvatore, Luca; Milan, Vittorino; Giannini, Gianrossano; Sinagra, Gianfranco

    2016-02-01

    Malfunctions of cardiac implantable electronical devices (CIED) have been described after high-energy radiation therapy even in the absence of direct exposure to ionizing radiation, due to diffusion of neutrons (n) causing soft errors in inner circuits. The purpose of the study was to analyse the effect of scattered radiation on different types and models of CIED and the possible sources of malfunctions. Fifty-nine explanted CIED were placed on an anthropomorphous phantom of tissue-equivalent material, and a high-energy photon (15 MV) radiotherapy course (total dose = 70 Gy) for prostate treatment was performed. All devices were interrogated before and after radiation. Radiation dose, the electromagnetic field, and neutron fluence at the CIED site were measured. Thirty-four pacemakers (PM) and 25 implantable cardioverter-defibrillators (ICD) were analysed. No malfunctions were detected before radiation. After radiation a software malfunction was evident in 13 (52%) ICD and 6 (18%) PM; no significant electromagnetic field or photon radiations were detected in the thoracic region. Neutron capture was demonstrated by the presence of the (198)Au((197)Au + n) or (192)Ir((191)Ir + n) isotope activation; it was significantly greater in ICD than in PM and non-significantly greater in damaged devices. A greater effect in St Jude PM (2/2 damaged), Boston (9/11), and St Jude ICD (3/6) and in older ICD models was observed; the year of production was not relevant in PM. High-energy radiation can cause different malfunctions on CIED, particularly ICD, even without direct exposure to ionizing radiation due to scattered radiation of neutrons produced by the linear accelerator. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  11. The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    Science.gov (United States)

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2014-11-01

    A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.

  12. Resistance Mechanisms in Hepatitis C Virus: implications for Direct-Acting Antiviral Use.

    Science.gov (United States)

    Bagaglio, Sabrina; Uberti-Foppa, Caterina; Morsica, Giulia

    2017-07-01

    Multiple direct-acting antiviral (DAA)-based regimens are currently approved that provide one or more interferon-free treatment options for hepatitis C virus (HCV) genotypes (G) 1-6. The choice of a DAA regimen, duration of therapy, and use of ribavirin depends on multiple viral and host factors, including HCV genotype, the detection of resistance-associated amino acid (aa) substitutions (RASs), prior treatment experience, and presence of cirrhosis. In regard to viral factors that may guide the treatment choice, the most important is the infecting genotype because a number of DAAs are genotype-designed. The potency and the genetic barrier may also impact the choice of treatment. One important and debated possible virologic factor that may negatively influence the response to DAAs is the presence of baseline RASs. Baseline resistance testing is currently not routinely considered or recommended for initiating HCV treatment, due to the overall high response rates (sustained virological response >90%) obtained. Exceptions are patients infected by HCV G1a when initiating treatment with simeprevir and elbasvir/grazoprevir or in those with cirrhosis prior to daclatasvir/sofosbuvir treatment because of natural polymorphisms demonstrated in sites of resistance. On the basis of these observations, first-line strategies should be optimized to overcome treatment failure due to HCV resistance.

  13. Mechanical Recanalization of Subacute Vessel Occlusion in Peripheral Arterial Disease with a Directional Atherectomy Catheter

    International Nuclear Information System (INIS)

    Massmann, Alexander; Katoh, Marcus; Shayesteh-Kheslat, Roushanak; Buecker, Arno

    2012-01-01

    Purpose: To retrospectively examine the technical feasibility and safety of directional atherectomy for treatment of subacute infrainguinal arterial vessel occlusions. Methods: Five patients (one woman, four men, age range 51–81 years) with peripheral arterial disease who experienced sudden worsening of their peripheral arterial disease–related symptoms during the last 2–6 weeks underwent digital subtraction angiography, which revealed vessel occlusion in native popliteal artery (n = 4) and in-stent occlusion of the superficial femoral artery (n = 1). Subsequently, all patients were treated by atherectomy with the SilverHawk (ev3 Endovascular, USA) device. Results: The mean diameter of treated vessels was 5.1 ± 1.0 mm. The length of the occlusion ranged 2–14 cm. The primary technical success rate was 100%. One patient experienced a reocclusion during hospitalization due to heparin-induced thrombocytopenia. There were no further periprocedural complications, in particular no peripheral embolizations, until hospital discharge or during the follow-up period of 1 year. Conclusion: The recanalization of infrainguinal arterial vessel occlusions by atherectomy with the SilverHawk device is technically feasible and safe. In our limited retrospective study, it was associated with a high technical success rate and a low procedure-related complication rate.

  14. Air Trapping Mechanism in Artificial Salvinia-Like Micro-Hairs Fabricated via Direct Laser Lithography

    Directory of Open Access Journals (Sweden)

    Omar Tricinci

    2017-12-01

    Full Text Available Salvinia leaves represent an extraordinary example of how nature found a strategy for the long term retainment of air, and thus oxygen, on a surface, the so-called ‘Salvinia effect’, thanks to the peculiar three-dimensional and hierarchical shape of the hairs covering the leaves. Here, starting from the natural model, we have microfabricated hairs inspired by those present on the Salvinia molesta leaves, by means of direct laser lithography. Artificial hairs, like their natural counterpart, are composed of a stalk and a crown-like head, and have been reproduced in the microscale since this ensures, if using a proper design, an air-retaining behavior even if the bulk structural material is hydrophilic. We have investigated the capability of air retainment inside the heads of the hairs that can last up to 100 h, demonstrating the stability of the phenomenon. For a given dimension of the head, the greater the number of filaments, the greater the amount of air that can be trapped inside the heads since the increase in the number of solid–air interfaces able to pin the liquid phase. For this reason, such type of pattern could be used for the fabrication of surfaces for controlled gas retainment and gas release in liquid phases. The range of applications would be quite large, including industrial, medical, and biological fields.

  15. Mechanism of adenylate kinase: Site-directed mutagenesis versus x-ray and NMR

    International Nuclear Information System (INIS)

    Tsai, Mingdaw; Yan, Honggao

    1991-01-01

    Controversy is an integral part of scientific research and is often a precursor to the truth. However, this lesson has been learned in a very hard way in the case of the structure-function relationship of adenylate kinase (AK), which catalyzes the interconversion between MgATP+AMP and MgADP+ADP. While this small kinase has been considered a model kinase and the enzyme-substrate interaction of AK was among the first investigated by X-ray crystallography and NMR the substrate binding sites deduced from the early studies by these two powerful techniques (termed the X-ray model and the NMR model, respectively) were dramatically different. Ironically, both models have had substantial impact on researchers in related fields. The problems have finally been dealt with since 1987 by the interplay between site-directed mutagenesis, X-ray, and NMR. The purpose of this review is not only to summarize the current knowledge in the structure-function relationship of adenylate kinase but also to accurately document and critically analyze historical developments in the hope that history will not be repeated

  16. Mechanical Recanalization of Subacute Vessel Occlusion in Peripheral Arterial Disease with a Directional Atherectomy Catheter

    Energy Technology Data Exchange (ETDEWEB)

    Massmann, Alexander, E-mail: Alexander.Massmann@uks.eu; Katoh, Marcus [Saarland University Hospital, Department of Diagnostic and Interventional Radiology (Germany); Shayesteh-Kheslat, Roushanak [Saarland University Hospital, Department of General Surgery, Visceral, Vascular, and Pediatric Surgery (Germany); Buecker, Arno [Saarland University Hospital, Department of Diagnostic and Interventional Radiology (Germany)

    2012-10-15

    Purpose: To retrospectively examine the technical feasibility and safety of directional atherectomy for treatment of subacute infrainguinal arterial vessel occlusions. Methods: Five patients (one woman, four men, age range 51-81 years) with peripheral arterial disease who experienced sudden worsening of their peripheral arterial disease-related symptoms during the last 2-6 weeks underwent digital subtraction angiography, which revealed vessel occlusion in native popliteal artery (n = 4) and in-stent occlusion of the superficial femoral artery (n = 1). Subsequently, all patients were treated by atherectomy with the SilverHawk (ev3 Endovascular, USA) device. Results: The mean diameter of treated vessels was 5.1 {+-} 1.0 mm. The length of the occlusion ranged 2-14 cm. The primary technical success rate was 100%. One patient experienced a reocclusion during hospitalization due to heparin-induced thrombocytopenia. There were no further periprocedural complications, in particular no peripheral embolizations, until hospital discharge or during the follow-up period of 1 year. Conclusion: The recanalization of infrainguinal arterial vessel occlusions by atherectomy with the SilverHawk device is technically feasible and safe. In our limited retrospective study, it was associated with a high technical success rate and a low procedure-related complication rate.

  17. Role of asphalt paver productivity in direction development of road mechanical engineering

    Directory of Open Access Journals (Sweden)

    Karpushko Marina

    2017-01-01

    Full Text Available Road construction machinery is one of the largest and stable sectors of national economy. With the help of road-building machinery, construction, maintenance and repair of highways are carried out. Modern system of road and building machines is a complex of high-performance machines and mechanisms, of large and small capacity and productivity. Expansion of paved roads network of both federal and local values, use of resource-saving technologies, increasing of pace and quality of work, ensuring of reliability and durability of highways have a major impact on the development of road construction machinery. The level of foreign road and construction machinery puts forward complex requirements for compliance with world safety and environmental standards, increasing equipment mobility, expanding areas of effective use and, finally, increasing its capacity and productivity. Article contains approach to the calculation of the operational productivity of asphalt pavers that takes into account technical characteristics and conditions of works production and contributes to the reliability of decisions on organization and management of road maintenance works on urban roads.

  18. Modelling the role of intrinsic electric fields in microtubules as an additional control mechanism of bi-directional intracellular transport.

    Science.gov (United States)

    Sataric, M V; Budinski-Petkovic, L; Loncarevic, I; Tuszynski, J A

    2008-01-01

    Active transport is essential for cellular function, while impaired transport has been linked to diseases such as neuronal degeneration. Much long distance transport in cells uses opposite polarity molecular motors of the kinesin and dynein families to move cargos along microtubules. It is clear that many types of cargo are moved by both sets of motors, and frequently in a reverse direction. The general question of how the direction of transport is regulated is still open. The mechanism of the cell's differential control of diverse cargos within the same cytoplasmic background is still unclear as is the answer to the question how endosomes and mitochondria move to different locations within the same cell. To answer these questions we postulate the existence of a local signaling mechanism used by the cell to specifically control different cargos. In particular, we propose an additional physical mechanism that works through the use of constant and alternating intrinsic (endogenous) electric fields as a means of controlling the speed and direction of microtubule-based transport. A specific model is proposed and analyzed in this paper. The model involves the rotational degrees of freedom of the C-termini of tubulin, their interactions and the coupling between elastic and dielectric degrees of freedom. Viscosity of the solution is also included and the resultant equation of motion is found as a nonlinear elliptic equation with dissipation. A particular analytical solution of this equation is obtained in the form of a kink whose properties are analyzed. It is concluded that this solution can be modulated by the presence of electric fields and hence may correspond to the observed behavior of motor protein transport along microtubules.

  19. Why direct effects of predation complicate the social brain hypothesis: And how incorporation of explicit proximate behavioral mechanisms might help.

    Science.gov (United States)

    van der Bijl, Wouter; Kolm, Niclas

    2016-06-01

    A growing number of studies have found that large brains may help animals survive by avoiding predation. These studies provide an alternative explanation for existing correlative evidence for one of the dominant hypotheses regarding the evolution of brain size in animals, the social brain hypothesis (SBH). The SBH proposes that social complexity is a major evolutionary driver of large brains. However, if predation both directly selects for large brains and higher levels of sociality, correlations between sociality and brain size may be spurious. We argue that tests of the SBH should take direct effects of predation into account, either by explicitly including them in comparative analyses or by pin-pointing the brain-behavior-fitness pathway through which the SBH operates. Existing data and theory on social behavior can then be used to identify precise candidate mechanisms and formulate new testable predictions. © 2016 WILEY Periodicals, Inc.

  20. Thermomechanical Modelling of Direct-Drive Friction Welding Applying a Thermal Pseudo Mechanical Model for the Generation of Heat

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Hattel, Jesper Henri

    2018-01-01

    In the present work a 2D a xisymmetric thermomechanical model of the direct-drive friction welding process is developed, taking the temperature dependent shear yield stress into account in the description of the heat generation, utilizing a recent thermal pseudo mechanical model originally...... developed for the friction stir welding (FSW) process. The model is implemented in ABAQUS/Explicit via a subroutine. The application in this case is joining of austenitic stainless steel rods with an outer diameter of 112 mm, used for manufacturing of exhaust gas valves for large two stroke marine engines....... The material properties in terms of the temperature dependent flowstress curves used both in the thermal and the mechanical constitutive description are extracted from compression tests performed between 20 °C and 1200 °C on a Gleeble 1500 thermomechanical simulator. Comparison between measured and simulated...

  1. Direct Pore Binding as a Mechanism for Isoflurane Inhibition of the Pentameric Ligand-gated Ion Channel ELIC.

    Science.gov (United States)

    Chen, Qiang; Kinde, Monica N; Arjunan, Palaniappa; Wells, Marta M; Cohen, Aina E; Xu, Yan; Tang, Pei

    2015-09-08

    Pentameric ligand-gated ion channels (pLGICs) are targets of general anesthetics, but molecular mechanisms underlying anesthetic action remain debatable. We found that ELIC, a pLGIC from Erwinia chrysanthemi, can be functionally inhibited by isoflurane and other anesthetics. Structures of ELIC co-crystallized with isoflurane in the absence or presence of an agonist revealed double isoflurane occupancies inside the pore near T237(6') and A244(13'). A pore-radius contraction near the extracellular entrance was observed upon isoflurane binding. Electrophysiology measurements with a single-point mutation at position 6' or 13' support the notion that binding at these sites renders isoflurane inhibition. Molecular dynamics simulations suggested that isoflurane binding was more stable in the resting than in a desensitized pore conformation. This study presents compelling evidence for a direct pore-binding mechanism of isoflurane inhibition, which has a general implication for inhibitory action of general anesthetics on pLGICs.

  2. Review on mechanism of directly fabricating wafer-scale graphene on dielectric substrates by chemical vapor deposition

    Science.gov (United States)

    Ning, Jing; Wang, Dong; Chai, Yang; Feng, Xin; Mu, Meishan; Guo, Lixin; Zhang, Jincheng; Hao, Yue

    2017-07-01

    To date, chemical vapor deposition on transition metal catalysts is a potential way to achieve low cost, high quality and uniform wafer-scale graphene. However, the removal and transfer process of the annoying catalytic metals underneath can bring large amounts of uncertain factors causing the performance deterioration of graphene, such as the pollution of surface polymeric residues, unmentioned doping and structural damages. Thus, to develop a technique of directly fabricating graphene on dielectric substrates is quite meaningful. In this review, we will present specific methods of catalyst- or transfer-free techniques for graphene growth and discuss the diversity of growth mechanisms.

  3. Study of nozzle deposit formation mechanism for direct injection gasoline engines; Chokufun gasoline engine yo nozzle no deposit seisei kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, M; Saito, A [Toyota Central Research and Development Labs., Inc., Aichi (Japan); Matsushita, S [Toyota Motor Corp., Aichi (Japan); Shibata, H [Nippon Soken, Inc., Tokyo (Japan); Niwa, Y [Denso Corp., Aichi (Japan)

    1997-10-01

    Nozzles in fuel injectors for direct injection gasoline engines are exposed to high temperature combustion gases and soot. In such a rigorous environment, it is a fear that fuel flow rate changes in injectors by deposit formation on nozzles. Fundamental factors of nozzle deposit formation were investigated through injector bench tests and engine dynamometer tests. Deposit formation processes were observed by SEM through engine dynamometer tests. The investigation results reveal nozzle deposit formation mechanism and how to suppress the deposit. 4 refs., 8 figs., 3 tabs.

  4. Direct observation and determination of the mechanisms governing mobility of asbestos in porous media

    Science.gov (United States)

    Seiphoori, A.; Ortiz, C. P.; Jerolmack, D. J.

    2017-12-01

    Transport of asbestos through soil by groundwater is typically considered to be negligible. There are indications, however, that under some conditions of pore-water/soil chemistry asbestos may become mobile, implying that buried contaminants could migrate from a disposal site and surface elsewhere. Shape, size and surface charge may influence the physical and chemical interactions of colloids with the soil matrix, and asbestos consists of elongated particles with different size and unique surface charge properties. Although chemical factors such as pH and ionic strength of pore water may affect the transport properties, the presence of dissolved organic carbon (DOC) has been identified to remarkably enhance the mobility of colloids including asbestos. To date, there is no explanation for how the presence of DOC may facilitate the mobilization of asbestos in soil - mainly because the soil medium has been treated as a black box without the possibility of observing particles within the matrix. Here, we investigated the mobility of chrysotile asbestos particles ( 10 um long) in porous media by developing a flow cell with an optically-transparent porous medium composed of granules of a refractive-index matched material. This enabled us to observe and track the particles within the water-saturated porous medium using in situ microscopy. The aqueous suspension of asbestos fibers was passed through this artificial soil, while the physical and chemical interaction of asbestos particles with the medium and their pore-scale distribution were analyzed. We studied the effects of changing solution chemistry (e.g., ionic strength, pH, and DOC content) on transport, attachment and aggregation of chrysotile particles. Experiments revealed a novel mechanism where the DOC-associated nanoparticles attach to chrysotile fibers by an electrostatic attraction, which facilitates their mobilization through the porous medium while modulating aggregation among fibers. Although pH and ionic

  5. Directed Self-Assembly of Star-Block Copolymers by Topographic Nanopatterns through Nucleation and Growth Mechanism.

    Science.gov (United States)

    Krishnan, Mohan Raj; Lu, Kai-Yuan; Chiu, Wen-Yu; Chen, I-Chen; Lin, Jheng-Wei; Lo, Ting-Ya; Georgopanos, Prokopios; Avgeropoulos, Apostolos; Lee, Ming-Chang; Ho, Rong-Ming

    2018-04-01

    Exploring the ordering mechanism and dynamics of self-assembled block copolymer (BCP) thin films under confined conditions are highly essential in the application of BCP lithography. In this study, it is aimed to examine the self-assembling mechanism and kinetics of silicon-containing 3-arm star-block copolymer composed of polystyrene (PS) and poly(dimethylsiloxane) blocks as nanostructured thin films with perpendicular cylinders and controlled lateral ordering by directed self-assembly using topographically patterned substrates. The ordering process of the star-block copolymer within fabricated topographic patterns with PS-functionalized sidewall can be carried out through the type of secondary (i.e., heterogeneous) nucleation for microphase separation initiated from the edge and/or corner of the topographic patterns, and directed to grow as well-ordered hexagonally packed perpendicular cylinders. The growth rate for the confined microphase separation is highly dependent upon the dimension and also the geometric texture of the preformed pattern. Fast self-assembly for ordering of BCP thin film can be achieved by lowering the confinement dimension and also increasing the concern number of the preformed pattern, providing a new strategy for the design of BCP lithography from the integration of top-down and bottom-up approaches. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. A review of micro-contact physics, materials, and failure mechanisms in direct-contact RF MEMS switches

    International Nuclear Information System (INIS)

    Basu, A; Adams, G G; McGruer, N E

    2016-01-01

    Direct contact, ohmic MEMS switches for RF applications have several advantages over other conventional switching devices. Advantages include lower insertion loss, higher isolation, and better switching figure-of-merit (cut-off frequency). The most important aspect of a direct-contact RF MEMS switch is the metal microcontact which can dictate the lifetime and reliability of the switch. Therefore, an understanding of contact reliability is essential for developing robust MEMS switches. This paper discusses and reviews the most important work done over the past couple of decades toward understanding ohmic micro-contacts. We initially discuss the contact mechanics and multi-physics models for studying Hertzian and multi-asperity contacts. We follow this with a discussion on models and experiments for studying adhesion. We then discuss experimental setups and the development of contact test stations by various groups for accelerated testing of microcontacts, as well as for analysis of contact reliability issues. Subsequently, we analyze a number of material transfer mechanisms in microcontacts under hot and cold switching conditions. We finally review the material properties that can help determine the selection of contact materials. A trade-off between contact resistance and high reliability is almost always necessary during selection of contact material; this paper discusses how the choice of materials can help address such trade-offs. (paper)

  7. Comparison of conventional reconstruction plate versus direct metal laser sintering plate: an in vitro mechanical characteristics study.

    Science.gov (United States)

    Xie, Pusheng; Ouyang, Hanbin; Deng, Yuping; Yang, Yang; Xu, Jing; Huang, Wenhua

    2017-09-02

    Additive manufacturing (AM) technology has helped to achieve several advances in the medical field, particularly as far as fabrication of implants is concerned. But the application of direct metal laser sintering (DMLS) bone plate is quite limited due to the indeterminate mechanical property. The purposes of this study were to characterize the biomechanical properties of the polished DMLS reconstruction plate and to compare these with the properties of commonly applied implants and to find whether the mechanical performance of DMLS plate meets the requirements for clinical application. In this study, we fabricated two groups of plates by DMLS and computer numerical control (CNC) techniques. After that, we polished all samples and investigated their roughness, components, hardness, static bending, and torsional performance. Moreover, cyclic bending tests and fractographic analysis were conducted. Statistical comparisons of the group by means of monotonic test data were made, and a qualitative comparison was performed to assess failures in fatigue. We found no differences in surface roughness or components after polishing, but the DMLS plate hardness is 7.42% (p direct application of these AM instruments in the operating room requires further validation including animal and clinical experiment.

  8. Direct writing and electro-mechanical characterization of Ag micro-patterns on polymer substrates for flexible electronics

    International Nuclear Information System (INIS)

    Torres Arango, Maria A.; Cokeley, Anna M.; Beard, Jared J.; Sierros, Konstantinos A.

    2015-01-01

    There is currently a great interest in developing flexible electrodes. Such components are used in most electronic devices from displays to solar cells to flexible sensors. To date most of them are fabricated using expensive vacuum techniques, and are based on transparent conducting oxides. These oxides are not entirely compatible with flexible substrates under the application of mechanical stresses, due to their brittle nature. Therefore, there is a need to explore novel low-cost, large-area fabrication methods to deposit alternative conducting materials with enhanced electro-mechanical performance. This work focuses on Ag patterns fabricated at low temperatures (below 150 °C) on flexible polyethylene naphthalate utilizing a robotic printing approach. Such lithography-free method minimizes material waste by printing exact amounts of inks on digitally predefined locations. Additionally, it allows a broad feature size range, from a few μm to a few mm, and a variety of ink viscosities for better pattern control. We investigate the synthesis and direct writing of Ag particle-based inks, patterned-on-flex as lines and grids in the μm scale. We report on a high-yield ink synthesis method (~ 61.6%) with controlled particle size. It is found that the electrical resistivity (1.75 ∗ 10"−"4 Ω cm) of the patterns is in the same range with similar particle-based conductive components. The correlation between annealing temperature, microstructural evolution, and electrical performance is established. Also, the optical transmittance of the patterns can be controlled to meet specific application requirements by regulating the substrate surface area covered. Finally, the mechanical behavior under both monotonic and cyclic conditions shows a superior performance compared to brittle counterparts and underlines the potential of such metallic micro-patterns to be utilized in a wide range of flexible electronic applications. It is believed that direct writing of Ag patterns on

  9. Direct writing and electro-mechanical characterization of Ag micro-patterns on polymer substrates for flexible electronics

    Energy Technology Data Exchange (ETDEWEB)

    Torres Arango, Maria A.; Cokeley, Anna M.; Beard, Jared J.; Sierros, Konstantinos A., E-mail: kostas.sierros@mail.wvu.edu

    2015-12-01

    There is currently a great interest in developing flexible electrodes. Such components are used in most electronic devices from displays to solar cells to flexible sensors. To date most of them are fabricated using expensive vacuum techniques, and are based on transparent conducting oxides. These oxides are not entirely compatible with flexible substrates under the application of mechanical stresses, due to their brittle nature. Therefore, there is a need to explore novel low-cost, large-area fabrication methods to deposit alternative conducting materials with enhanced electro-mechanical performance. This work focuses on Ag patterns fabricated at low temperatures (below 150 °C) on flexible polyethylene naphthalate utilizing a robotic printing approach. Such lithography-free method minimizes material waste by printing exact amounts of inks on digitally predefined locations. Additionally, it allows a broad feature size range, from a few μm to a few mm, and a variety of ink viscosities for better pattern control. We investigate the synthesis and direct writing of Ag particle-based inks, patterned-on-flex as lines and grids in the μm scale. We report on a high-yield ink synthesis method (~ 61.6%) with controlled particle size. It is found that the electrical resistivity (1.75 ∗ 10{sup −4} Ω cm) of the patterns is in the same range with similar particle-based conductive components. The correlation between annealing temperature, microstructural evolution, and electrical performance is established. Also, the optical transmittance of the patterns can be controlled to meet specific application requirements by regulating the substrate surface area covered. Finally, the mechanical behavior under both monotonic and cyclic conditions shows a superior performance compared to brittle counterparts and underlines the potential of such metallic micro-patterns to be utilized in a wide range of flexible electronic applications. It is believed that direct writing of Ag patterns

  10. Oncogenic Receptor Tyrosine Kinases Directly Phosphorylate Focal Adhesion Kinase (FAK) as a Resistance Mechanism to FAK-Kinase Inhibitors.

    Science.gov (United States)

    Marlowe, Timothy A; Lenzo, Felicia L; Figel, Sheila A; Grapes, Abigail T; Cance, William G

    2016-12-01

    Focal adhesion kinase (FAK) is a major drug target in cancer and current inhibitors targeted to the ATP-binding pocket of the kinase domain have entered clinical trials. However, preliminary results have shown limited single-agent efficacy in patients. Despite these unfavorable data, the molecular mechanisms that drive intrinsic and acquired resistance to FAK-kinase inhibitors are largely unknown. We have demonstrated that receptor tyrosine kinases (RTK) can directly bypass FAK-kinase inhibition in cancer cells through phosphorylation of FAK's critical tyrosine 397 (Y397). We also showed that HER2 forms a direct protein-protein interaction with the FAK-FERM-F1 lobe, promoting direct phosphorylation of Y397. In addition, FAK-kinase inhibition induced two forms of compensatory RTK reprogramming: (i) the rapid phosphorylation and activation of RTK signaling pathways in RTK High cells and (ii) the long-term acquisition of RTKs novel to the parental cell line in RTK Low cells. Finally, HER2 +: cancer cells displayed resistance to FAK-kinase inhibition in 3D growth assays using a HER2 isogenic system and HER2 + cancer cell lines. Our data indicate a novel drug resistance mechanism to FAK-kinase inhibitors whereby HER2 and other RTKs can rescue and maintain FAK activation (pY397) even in the presence of FAK-kinase inhibition. These data may have important ramifications for existing clinical trials of FAK inhibitors and suggest that individual tumor stratification by RTK expression would be important to predict patient response to FAK-kinase inhibitors. Mol Cancer Ther; 15(12); 3028-39. ©2016 AACR. ©2016 American Association for Cancer Research.

  11. WHAMM Directs the Arp2/3 Complex to the ER for Autophagosome Biogenesis through an Actin Comet Tail Mechanism.

    Science.gov (United States)

    Kast, David J; Zajac, Allison L; Holzbaur, Erika L F; Ostap, E Michael; Dominguez, Roberto

    2015-06-29

    Nucleation-promoting factors (NPFs) control the spatio-temporal activity of Arp2/3 complex in cells]. Thus, WASP and the WAVE complex direct the formation of branched actin networks at the leading edge during cell motility and endo/exocytosis, whereas the WASH complex is involved in endosomal transport. Less understood are WHAMM and JMY, two NPFs with similar domain architecture. JMY is found in the nucleus and the cytosol and is involved in transcriptional regulation, cell motility, and trans-Golgi transport. WHAMM was reported to bind microtubules and to be involved in ER to cis-Golgi transport. Here, we show that WHAMM directs the activity of Arp2/3 complex for autophagosome biogenesis through an actin-comet tail motility mechanism. Macroautophagy--the process by which cytosolic material is engulfed into autophagosomes for degradation and/or recycling--was recently shown to involve actin, but the mechanism is unknown. We found that WHAMM forms puncta that colocalize and comigrate with the autophagy markers LC3, DFCP1, and p62 through a WHAMM-dependent actin-comet tail mechanism. Under starvation, WHAMM and actin are observed at the interface between neighboring autophagosomes, whose number and size increase with WHAMM expression. Interfering with actin polymerization, inhibiting Arp2/3 complex, knocking down WHAMM, or blocking its interaction with Arp2/3 complex through mutagenesis all inhibit comet tail formation and reduce the size and number of autophagosomes. Finally, JMY shows similar localization to WHAMM and could be involved in similar processes. These results reveal a link between Arp2/3-complex-dependent actin assembly and autophagy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. A Direct Kinematics Problem Solution for the Three-degree-of-freedom Parallel Structure Manipulator Based on Crank Mechanism

    Directory of Open Access Journals (Sweden)

    V. N. Paschenko

    2015-01-01

    Full Text Available The paper describes a mechanism representing a kind of mechanisms of parallel kinematics with three degrees of freedom based on the crank mechanism. This mechanism consists of two platforms, namely: the lower fixed and the upper movable. The upper platform is connected to the lower one by six movable elements, three of which are rods attached to the bases by means of spherical joints, and another three have a crank structure.The paper shows an approach to the solution of a direct task of kinematics based on mathematical modeling. The inverse problem of kinematics is formulated as follows: at specified angles of rotation drive (the values of generalized coordinates to determine the position of the top mobile platform.To solve this problem has been used a mathematical model describing the proposed system. On the basis of the constructed model were made the necessary calculations that allowed us using the values of crank angles connected with the engines to determine the position of the platform in space. To solve the problem we used the method of virtual points to reduce the number of equations and unknowns, which determine the position of the upper platform in space, at a crucial system from eighteen to nine, thus simplifying the solution.To check the solution correctness was carried out numerical experiment. Each generalized coordinate took on values in the range from -30 ° to 30 °; for them a direct positional problem was solved, and its result was inserted, as initial data, in the previous solved and proven inverse problem on the position of the platform under study.The paper presents comparative results of measurements with the calculated values of the generalized coordinates and draws the appropriate conclusions, that this model is in good compliance with the results observed in practice. One of the distinctive features of the proposed approach is that rotation angles of engines are used as the generalized coordinates. This allowed us

  13. Microstructural and Mechanical Characterization of a Custom-Built Implant Manufactured in Titanium Alloy by Direct Metal Laser Sintering

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Larosa

    2014-08-01

    Full Text Available Custom-built implants manufacture has always presented difficulties which result in high cost and complex fabrication, mainly due to patients’ anatomical differences. The solution has been to produce prostheses with different sizes and use the one that best suits each patient. Additive manufacturing technology, incorporated into the medical field in the late 80's, has made it possible to obtain solid biomodels facilitating surgical procedures and reducing risks. Furthermore, this technology has been used to produce implants especially designed for a particular patient, with sizes, shapes, and mechanical properties optimized, for different areas of medicine such as craniomaxillofacial surgery. In this work, the microstructural and mechanical properties of Ti6Al4V samples produced by direct metal laser sintering (DMLS are studied. The microstructural and mechanical characterizations have been made by optical and scanning electron microscopy, X-ray diffraction, and microhardness and tensile tests. Samples produced by DMLS have a microstructure constituted by hexagonal α′ martensite with acicular morphology. An average microhardness of 370 HV was obtained and the tensile tests showed ultimate strength of 1172 MPa, yield strength of 957 MPa, and elongation at rupture of 11%.

  14. Physical mechanisms of SiNx layer structuring with ultrafast lasers by direct and confined laser ablation

    International Nuclear Information System (INIS)

    Rapp, S.; Heinrich, G.; Wollgarten, M.; Huber, H. P.; Schmidt, M.

    2015-01-01

    In the production process of silicon microelectronic devices and high efficiency silicon solar cells, local contact openings in thin dielectric layers are required. Instead of photolithography, these openings can be selectively structured with ultra-short laser pulses by confined laser ablation in a fast and efficient lift off production step. Thereby, the ultrafast laser pulse is transmitted by the dielectric layer and absorbed at the substrate surface leading to a selective layer removal in the nanosecond time domain. Thermal damage in the substrate due to absorption is an unwanted side effect. The aim of this work is to obtain a deeper understanding of the physical laser-material interaction with the goal of finding a damage-free ablation mechanism. For this, thin silicon nitride (SiN x ) layers on planar silicon (Si) wafers are processed with infrared fs-laser pulses. Two ablation types can be distinguished: The known confined ablation at fluences below 300 mJ/cm 2 and a combined partial confined and partial direct ablation at higher fluences. The partial direct ablation process is caused by nonlinear absorption in the SiN x layer in the center of the applied Gaussian shaped laser pulses. Pump-probe investigations of the central area show ultra-fast reflectivity changes typical for direct laser ablation. Transmission electron microscopy results demonstrate that the Si surface under the remaining SiN x island is not damaged by the laser ablation process. At optimized process parameters, the method of direct laser ablation could be a good candidate for damage-free selective structuring of dielectric layers on absorbing substrates

  15. [Effect of transpulmonary pressure-directed mechanical ventilation on respiration in severe acute pancreatitis patient with intraabdominal hypertension].

    Science.gov (United States)

    Wu, Xiaoyan; Zheng, Ruiqiang; Lin, Hua; Zhuang, Zhiqing; Zhang, Min; Yan, Peixia

    2015-10-20

    To assess the effect of mehanical ventilation (MV) guided by transpulmonary pressure (Ptp) on respiratory mechanics and gas exchange in severe acute pancreatitis patient with intraabdominal hypertension. Twelve severe acute pancreatitis patient with intraabdominal hypertension and acute respiratory distress syndrome(ARDS) underwent mechanical ventilation were involved from Jan to Dec 2013. PEEP levels were set to achieve a Ptp of 0 to 10 cm of water at end expiration. We also limited tidal volume to keep Ptp at less than 25 cm of water at end inspiration. Respiratory mechanics and gas-exchange were measured. Plat pressure (Pplat) increased and the compliance of chest wall (Ccw) decreased when intraabdominal pressure (IAP) increased. Pplat correlated with IAP positively (r2=0.741 9, P0.05). Compared with baseline, after guiding MV with Ptp, the Level of PEEP (14.6±4.2) cmH2O vs (8.3±2.0) cmH2O, and Ptp-e (1.5±0.5) cmH2O vs (-2.3±1.4) cmH2O increased (P0.05). Ptp-e correlated with PEEP (r2=0.549, P0.05). Compared with baseline, lung compliance (CL) (48.1±10.3) cmH2O vs (25.7±6.4) cmH2O and oxygenation index (PaO2/FiO2) (235±48) mmHg vs (160±35) mmHg improved obviously (P0.05). Transpulmonary pressure-directed mechanical ventilation in ARDS secondary to severe acute pancreatitis patient with intraabdominal hypertension could not only recruit the collapsed alveoli, improve lung compliance, increase oxygenation index and decrease dead space ventilation but also monitor lung stress to avoid alveoli overinflation, which might be lung protective.

  16. Investigation of chemical and electrochemical reactions mechanisms in a direct carbon fuel cell using olive wood charcoal as sustainable fuel

    Science.gov (United States)

    Elleuch, Amal; Halouani, Kamel; Li, Yongdan

    2015-05-01

    Direct carbon fuel cell (DCFC) is a high temperature fuel cell using solid carbon as fuel. The use of environmentally friendly carbon material constitutes a promising option for the DCFC future. In this context, this paper focuses on the use of biomass-derived charcoal renewable fuel. A practical investigation of Tunisian olive wood charcoal (OW-C) in planar DCFCs is conducted and good power density (105 mW cm-2) and higher current density (550 mA cm-2) are obtained at 700 °C. Analytical and predictive techniques are performed to explore the relationships between fuel properties and DCFC chemical and electrochemical mechanisms. High carbon content, carbon-oxygen groups and disordered structure, are the key parameters allowing the achieved good performance. Relatively complex chain reactions are predicted to explain the gas evolution within the anode. CO, H2 and CH4 participation in the anodic reaction is proved.

  17. The Reaction Mechanism of Claisen Rearrangement Obtained by Transition State Spectroscopy and Single Direct-Dynamics Trajectory

    Directory of Open Access Journals (Sweden)

    Takayoshi Kobayashi

    2013-02-01

    Full Text Available Chemical bond breaking and formation during chemical reactions can be observed using “transition state spectroscopy”. Comparing the measurement result of the transition state spectroscopy with the simulation result of single direct-dynamics trajectory, we have elucidated the reaction dynamics of Claisen rearrangement of allyl vinyl ether. Observed the reaction of the neat sample liquid, we have estimated the time constants of transformation from straight-chain structure to aromatic-like six-membered ring structure forming the C1-C6 bond. The result clarifies that the reaction proceeds via three steps taking longer time than expected from the gas phase calculation. This finding provides new hypothesis and discussions, helping the development of the field of reaction mechanism analysis.

  18. Bacterial foraging-optimized PID control of a two-wheeled machine with a two-directional handling mechanism.

    Science.gov (United States)

    Goher, K M; Fadlallah, S O

    2017-01-01

    This paper presents the performance of utilizing a bacterial foraging optimization algorithm on a PID control scheme for controlling a five DOF two-wheeled robotic machine with two-directional handling mechanism. The system under investigation provides solutions for industrial robotic applications that require a limited-space working environment. The system nonlinear mathematical model, derived using Lagrangian modeling approach, is simulated in MATLAB/Simulink ® environment. Bacterial foraging-optimized PID control with decoupled nature is designed and implemented. Various working scenarios with multiple initial conditions are used to test the robustness and the system performance. Simulation results revealed the effectiveness of the bacterial foraging-optimized PID control method in improving the system performance compared to the PID control scheme.

  19. Effects of Changing Hot Rolling Direction on Microstructure, Texture and Mechanical Properties of Cu-2.7Be Sheets

    Science.gov (United States)

    Zhu, Daibo; Liu, Chuming; Yu, Haijun; Han, Tan

    2018-03-01

    A hot rolling scheme (cross-rolling and unidirectional rolling) was adopted to process Cu-2.7Be sheets used as multiplier dynodes in photomultiplier. The effects of changing rolling direction on microstructure, texture and mechanical properties were studied by a combination of XRD, EBSD and TEM. It was found that higher copper-type texture and lower brass texture intensity were obtained in the ultimately cross-rolling (CR) sheet compared with the unidirectional rolling (UR) sheet.The EBSD results indicated that the grain orientation from mainly for UR sample turns to random for CR sample. Great enhancements in YS and UTS after unidirectional rolling were attributed to the massive and polygonal γ precipitates. The CR sample exhibited lower anisotropy, because of the increase of S and γ precipitates with spherical and tiny shape.

  20. Patient-directed music therapy reduces anxiety and sedation exposure in mechanically-ventilated patients: a research critique.

    Science.gov (United States)

    Gullick, Janice G; Kwan, Xiu Xian

    2015-05-01

    This research appraisal, guided by the CASP Randomised Controlled Trial Checklist, critiques a randomised, controlled trial of patient-directed music therapy compared to either noise-cancelling headphones or usual care. This study recruited 373 alert, mechanically-ventilated patients across five intensive care units in the United States. The Music Assessment Tool, administered by a music therapist, facilitated music selection by participants in the intervention group. Anxiety was measured using the VAS-A scale. Sedation exposure was measured by both sedation frequency and by sedation intensity using a daily sedation intensity score. Context for the data was supported by an environmental scan form recording unit activity and by written comments from nurses about the patient's responses to the protocol. Patient-directed music therapy allowed a significant reduction in sedation frequency compared to noise-cancelling headphones and usual care participants. Patient-directed music therapy led to significantly lower anxiety and sedation intensity compared to usual care, but not compared to noise-cancelling headphones. This is a robust study with clear aims and a detailed description of research methods and follow-up. While no participants were lost to follow-up, not all were included in the analysis: 37% did not have the minimum of two anxiety assessments for comparison and 23% were not included in sedation analysis. While some participants utilised the intervention or active control for many hours-per-day, half the music therapy participants listened for 12min or less per day and half of the noise-cancelling headphone participants did not appear to use them. While the results suggest that patient-directed music therapy and noise-cancelling headphones may be useful and cost-effective interventions that lead to an overall improvement in anxiety and sedation exposure, these may appeal to a subset of ICU patients. The self-directed use of music therapy and noise

  1. Comparing the similarity of responses received from studies in Amazon's Mechanical Turk to studies conducted online and with direct recruitment.

    Directory of Open Access Journals (Sweden)

    Christoph Bartneck

    Full Text Available Computer and internet based questionnaires have become a standard tool in Human-Computer Interaction research and other related fields, such as psychology and sociology. Amazon's Mechanical Turk (AMT service is a new method of recruiting participants and conducting certain types of experiments. This study compares whether participants recruited through AMT give different responses than participants recruited through an online forum or recruited directly on a university campus. Moreover, we compare whether a study conducted within AMT results in different responses compared to a study for which participants are recruited through AMT but which is conducted using an external online questionnaire service. The results of this study show that there is a statistical difference between results obtained from participants recruited through AMT compared to the results from the participant recruited on campus or through online forums. We do, however, argue that this difference is so small that it has no practical consequence. There was no significant difference between running the study within AMT compared to running it with an online questionnaire service. There was no significant difference between results obtained directly from within AMT compared to results obtained in the campus and online forum condition. This may suggest that AMT is a viable and economical option for recruiting participants and for conducting studies as setting up and running a study with AMT generally requires less effort and time compared to other frequently used methods. We discuss our findings as well as limitations of using AMT for empirical studies.

  2. Comparing the similarity of responses received from studies in Amazon's Mechanical Turk to studies conducted online and with direct recruitment.

    Science.gov (United States)

    Bartneck, Christoph; Duenser, Andreas; Moltchanova, Elena; Zawieska, Karolina

    2015-01-01

    Computer and internet based questionnaires have become a standard tool in Human-Computer Interaction research and other related fields, such as psychology and sociology. Amazon's Mechanical Turk (AMT) service is a new method of recruiting participants and conducting certain types of experiments. This study compares whether participants recruited through AMT give different responses than participants recruited through an online forum or recruited directly on a university campus. Moreover, we compare whether a study conducted within AMT results in different responses compared to a study for which participants are recruited through AMT but which is conducted using an external online questionnaire service. The results of this study show that there is a statistical difference between results obtained from participants recruited through AMT compared to the results from the participant recruited on campus or through online forums. We do, however, argue that this difference is so small that it has no practical consequence. There was no significant difference between running the study within AMT compared to running it with an online questionnaire service. There was no significant difference between results obtained directly from within AMT compared to results obtained in the campus and online forum condition. This may suggest that AMT is a viable and economical option for recruiting participants and for conducting studies as setting up and running a study with AMT generally requires less effort and time compared to other frequently used methods. We discuss our findings as well as limitations of using AMT for empirical studies.

  3. Effect of solidification parameters on mechanical properties of directionally solidified Al-Rich Al-Cu alloys

    Science.gov (United States)

    Çadırlı, Emin

    2013-05-01

    Al(100-x)-Cux alloys (x=3 wt%, 6 wt%, 15 wt%, 24 wt% and 33 wt%) were prepared using metals of 99.99% high purity in vacuum atmosphere. These alloys were directionally solidified under steady-state conditions by using a Bridgman-type directional solidification furnace. Solidification parameters (G, V and ), microstructure parameters (λ1, λ2 and λE) and mechanical properties (HV, σ) of the Al-Cu alloys were measured. Microstructure parameters were expressed as functions of solidification parameters by using a linear regression analysis. The dependency of HV, σ on the cooling rate, microstructure parameters and composition were determined. According to experimental results, the microhardness and ultimate tensile strength of the solidified samples was increased by increasing the cooling rate and Cu content, but decreased with increasing microstructure parameters. The microscopic fracture surfaces of the different samples were observed using scanning electron microscopy. Fractographic analysis of the tensile fracture surfaces showed that the type of fracture significantly changed from ductile to brittle depending on the composition.

  4. Mechanical, tribological and corrosion properties of CrBN films deposited by combined direct current and radio frequency magnetron sputtering

    International Nuclear Information System (INIS)

    Jahodova, Vera; Ding, Xing-zhao; Seng, Debbie H.L.; Gulbinski, W.; Louda, P.

    2013-01-01

    Cr–B–N films were deposited on stainless steel substrates by a combined direct current and radio frequency (RF) reactive unbalanced magnetron sputtering process using two elemental Cr and one compound BN targets. Boron content in the as-deposited films was qualitatively analyzed by time-of-flight secondary ion mass spectroscopy. Films' microstructure, mechanical and tribological properties were characterized by X-ray diffraction, nanoindentation and pin-on-disk tribometer experiments. Corrosion behavior of the Cr–B–N films was evaluated by electrochemical potentiodynamic polarization method in a 3 wt.% NaCl solution. All the films were crystallized into a NaCl-type cubic structure. At lower RF power applied on the BN target (≤ 600 W), films are relatively randomly oriented, and films' crystallinity increased with increasing RF power. With increasing RF power further (≥ 800 W), films became (200) preferentially oriented, and films' crystallinity decreased gradually. With incorporation of a small amount of boron atoms into the CrN films, hardness, wear- and corrosion-resistance were all improved evidently. The best wear and corrosion resistance was obtained for the film deposited with 600 W RF power applied on the BN target. - Highlights: • CrBN films deposited by direct current and radio frequency magnetron sputtering. • CrBN exhibited higher hardness, wear- and corrosion-resistance than pure CrN. • The best wear- and corrosion-resistant film was deposited with 600 W RF power

  5. Optimization of mechanical properties of Al-metal matrix composite produced by direct fusion of beverage cans

    International Nuclear Information System (INIS)

    Carrasco, C.; Inzunza, G.; Camurri, C.; Rodríguez, C.; Radovic, L.; Soldera, F.; Suarez, S.

    2014-01-01

    The collection of used beverage cans is limited in countries where they are not fabricated; their low value does not justify the extra charge of exporting them for further processing. To address this increasingly serious problem, here we optimize the properties of an aluminum metal matrix composite (Al-MMC) obtained through direct fusion of beverage cans by using the slag generated in the melting process as reinforcement. This method consists of a modified rheocasting process followed by thixoforming. Our main operational variable is the shear rate applied to a semi-solid bath, subsequent to which a suitable heat treatment (T8) is proposed to improve the mechanical properties. The microstructure, the phases obtained and their effect on composite mechanical properties are analyzed. The composite material produced has, under the best conditions, a yield stress of 175 MPa and a tensile strength of 273 MPa. These results demonstrate that the proposed process does indeed transform the used beverage cans into promising composite materials, e.g., for structural applications

  6. Comparisons of microstructures and texture and mechanical properties of magnesium alloy fabricated by compound extrusion and direct extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Hu, H.-J., E-mail: hhj@cqut.edu.cn [Chongqing University of Technology, Chongqing 400050 (China); PLA Chongqing Logistics Engineering College, 401311 (China); Ying, Y.-L. [Chongqing University of Technology, Chongqing 400050 (China); Ou, Z.-W. [PLA Chongqing Logistics Engineering College, 401311 (China); Wang, X.-Q. [The University of Alabama, Tuscaloosa, AL 35487 (United States)

    2017-05-17

    In this study, microstructure evolution, textures and mechanical properties of AZ61 magnesium alloy were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile tests. The samples were processed by a new compound extrusion (CE) which combines direct extrusion (DE) and two steps of equal channel anger extrusion (ECAE). The results show that CE process can refine the microstructure more effectively than the DE process. The CE-fabricated samples have a weaker texture (0002), and a more fine and homogeneous microstructures, which attributes to the additional two steps of ECAE in CE process. In CE process, twin dynamic recrystallization and rotational dynamic recrystallization occurred, which enhances the refinement of the grains and weakening of the texture. In addition, the samples fabricated by CE process display a higher tensile properties (yield strength, tensile strength and elongation) with an excellent balance of strength and tensile ductility. Based on this study, severe plastic deformation (SPD) techniques combining conventional DE and two steps ECAE into a single process are feasibility to improve the mechanical properties of AZ61 Mg alloy.

  7. Optimization of mechanical properties of Al-metal matrix composite produced by direct fusion of beverage cans

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco, C., E-mail: ccarrascoc@udec.cl [Department of Materials Engineering, University of Concepción, Edmundo Larenas 270, Concepción (Chile); Inzunza, G.; Camurri, C.; Rodríguez, C. [Department of Materials Engineering, University of Concepción, Edmundo Larenas 270, Concepción (Chile); Radovic, L. [Department of Chemical Engineering, University of Concepción, Edmundo Larenas 129, Concepción (Chile); Department of Energy and Geo-Environmental Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Soldera, F.; Suarez, S. [Department of Materials Science, Saarland University, Campus D3.3, 66123 Saarbrücken (Germany)

    2014-11-03

    The collection of used beverage cans is limited in countries where they are not fabricated; their low value does not justify the extra charge of exporting them for further processing. To address this increasingly serious problem, here we optimize the properties of an aluminum metal matrix composite (Al-MMC) obtained through direct fusion of beverage cans by using the slag generated in the melting process as reinforcement. This method consists of a modified rheocasting process followed by thixoforming. Our main operational variable is the shear rate applied to a semi-solid bath, subsequent to which a suitable heat treatment (T8) is proposed to improve the mechanical properties. The microstructure, the phases obtained and their effect on composite mechanical properties are analyzed. The composite material produced has, under the best conditions, a yield stress of 175 MPa and a tensile strength of 273 MPa. These results demonstrate that the proposed process does indeed transform the used beverage cans into promising composite materials, e.g., for structural applications.

  8. Photobiomodulation Mitigates Diabetes-Induced Retinopathy by Direct and Indirect Mechanisms: Evidence from Intervention Studies in Pigmented Mice.

    Science.gov (United States)

    Saliba, Alexandra; Du, Yunpeng; Liu, Haitao; Patel, Shyam; Roberts, Robin; Berkowitz, Bruce A; Kern, Timothy S

    2015-01-01

    Daily application of far-red light from the onset of diabetes mitigated diabetes-induced abnormalities in retinas of albino rats. Here, we test the hypothesis that photobiomodulation (PBM) is effective in diabetic, pigmented mice, even when delayed until weeks after onset of diabetes. Direct and indirect effects of PBM on the retina also were studied. Diabetes was induced in C57Bl/6J mice using streptozotocin. Some diabetics were exposed to PBM therapy (4 min/day; 670 nm) daily. In one study, mice were diabetic for 4 weeks before initiation of PBM for an additional 10 weeks. Retinal oxidative stress, inflammation, and retinal function were measured. In some mice, heads were covered with a lead shield during PBM to prevent direct illumination of the eye, or animals were treated with an inhibitor of heme oxygenase-1. In a second study, PBM was initiated immediately after onset of diabetes, and administered daily for 2 months. These mice were examined using manganese-enhanced MRI to assess effects of PBM on transretinal calcium channel function in vivo. PBM intervention improved diabetes-induced changes in superoxide generation, leukostasis, expression of ICAM-1, and visual performance. PBM acted in part remotely from the retina because the beneficial effects were achieved even with the head shielded from the light therapy, and because leukocyte-mediated cytotoxicity of retinal endothelial cells was less in diabetics treated with PBM. SnPP+PBM significantly reduced iNOS expression compared to PBM alone, but significantly exacerbated leukostasis. In study 2, PBM largely mitigated diabetes-induced retinal calcium channel dysfunction in all retinal layers. PBM induces retinal protection against abnormalities induced by diabetes in pigmented animals, and even as an intervention. Beneficial effects on the retina likely are mediated by both direct and indirect mechanisms. PBM is a novel non-pharmacologic treatment strategy to inhibit early changes of diabetic retinopathy.

  9. Photobiomodulation Mitigates Diabetes-Induced Retinopathy by Direct and Indirect Mechanisms: Evidence from Intervention Studies in Pigmented Mice.

    Directory of Open Access Journals (Sweden)

    Alexandra Saliba

    Full Text Available Daily application of far-red light from the onset of diabetes mitigated diabetes-induced abnormalities in retinas of albino rats. Here, we test the hypothesis that photobiomodulation (PBM is effective in diabetic, pigmented mice, even when delayed until weeks after onset of diabetes. Direct and indirect effects of PBM on the retina also were studied.Diabetes was induced in C57Bl/6J mice using streptozotocin. Some diabetics were exposed to PBM therapy (4 min/day; 670 nm daily. In one study, mice were diabetic for 4 weeks before initiation of PBM for an additional 10 weeks. Retinal oxidative stress, inflammation, and retinal function were measured. In some mice, heads were covered with a lead shield during PBM to prevent direct illumination of the eye, or animals were treated with an inhibitor of heme oxygenase-1. In a second study, PBM was initiated immediately after onset of diabetes, and administered daily for 2 months. These mice were examined using manganese-enhanced MRI to assess effects of PBM on transretinal calcium channel function in vivo.PBM intervention improved diabetes-induced changes in superoxide generation, leukostasis, expression of ICAM-1, and visual performance. PBM acted in part remotely from the retina because the beneficial effects were achieved even with the head shielded from the light therapy, and because leukocyte-mediated cytotoxicity of retinal endothelial cells was less in diabetics treated with PBM. SnPP+PBM significantly reduced iNOS expression compared to PBM alone, but significantly exacerbated leukostasis. In study 2, PBM largely mitigated diabetes-induced retinal calcium channel dysfunction in all retinal layers.PBM induces retinal protection against abnormalities induced by diabetes in pigmented animals, and even as an intervention. Beneficial effects on the retina likely are mediated by both direct and indirect mechanisms. PBM is a novel non-pharmacologic treatment strategy to inhibit early changes of diabetic

  10. Transjugular Intrahepatic Portosystemic Shunt, Mechanical Aspiration Thrombectomy, and Direct Thrombolysis in the Treatment of Acute Portal and Superior Mesenteric Vein Thrombosis

    International Nuclear Information System (INIS)

    Ferro, Carlo; Rossi, Umberto G.; Bovio, Giulio; Dahamane, M'Hamed; Centanaro, Monica

    2007-01-01

    A patient was admitted because of severe abdominal pain, anorexia, and intestinal bleeding. Contrast-enhanced multidetector computed tomography demonstrated acute portal and superior mesenteric vein thrombosis (PSMVT). The patient was treated percutaneously with transjugular intrahepatic portosystemic shunt (TIPS), mechanical aspiration thrombectomy, and direct thrombolysis, and 1 week after the procedure, complete patency of the portal and superior mesenteric veins was demonstrated. TIPS, mechanical aspiration thrombectomy, and direct thrombolysis together are promising endovascular techniques for the treatment of symptomatic acute PSMVT

  11. Characterisation of dispersion mechanisms in an urban catchment using a deterministic spatially distributed direct hydrograph travel time model

    Science.gov (United States)

    Rossel, F.; Gironas, J. A.

    2012-12-01

    The link between stream network structure and hydrologic response for natural basins has been extensively studied. It is well known that stream network organization and flow dynamics in the reaches combine to shape the hydrologic response of natural basins. Geomorphologic dispersion and hydrodynamic dispersion along with hillslope processes control to a large extent the overall variance of the hydrograph, particularly under the assumption of constant celerity throughout the basin. In addition, a third mechanism referred as to kinematic dispersion becomes relevant when considering spatial variations of celerity. On contrary, the link between the drainage network structure and overall urban terrain, and the hydrologic response in urban catchments has been much less studied. In particular, the characterization of the different dispersion mechanisms within urban areas remains to be better understood. In such areas artificial elements are expected to contribute to the total dispersion due to the variety of geometries and the spatial distribution of imperviousness. This work quantifies the different dispersion mechanisms in an urban catchment, focusing on their relevance and the spatial scales involved. For this purpose we use the Urban Morpho-climatic Instantaneous Unit Hydrograph model, a deterministic spatially distributed direct hydrograph travel time model, which computes travel times in hillslope, pipe, street and channel cells using formulations derived from kinematic wave theory. The model was applied to the Aubeniere catchment, located in Nantes, France. Unlike stochastic models, this deterministic model allows the quantification of dispersion mechanism at the local scale (i.e. the grid-cell). We found that kinematic dispersion is more relevant for small storm events, whereas geomorphologic dispersion becomes more significant for larger storms, as the mean celerity within the catchment increases. In addition, the total dispersion relates to the drainage area in

  12. Rehearsal of To-Be-Remembered Items Is Unnecessary to Perform Directed Forgetting within Working Memory: Support for an Active Control Mechanism

    Science.gov (United States)

    Festini, Sara B.; Reuter-Lorenz, Patricia A.

    2017-01-01

    Directed forgetting tasks instruct people to forget targeted memoranda. In the context of working memory, people attempt to forget representations that are currently held in mind. Here, we evaluated candidate mechanisms of directed forgetting within working memory, by (a) testing the influence of articulatory suppression, a rehearsal-reducing and…

  13. World Health Organization's Innovative Direct Disbursement Mechanism for Payment of Grassroots Immunization Personnel and Operations in Nigeria: 2004–2015

    Science.gov (United States)

    Yehualashet, Yared G.; Wadda, Alieu; Agblewonu, Koffi B.; Zhema, Theophilus; Ibrahim, Al-asi A.; Corr, Alhagie; Linkins, Jennifer; Mkanda, Pascal; Vaz, Rui G.; Nsubuga, Peter; Ashogbon, Daniel

    2016-01-01

    Background. Following the 1988 World Health Assembly resolution to eradicate polio, the government of Nigeria, with support from partners, has been implementing several rounds of supplementary immunization activities (SIAs) each year. In addition to the technical requirements, the success of the polio eradication initiative depends on timely provision of adequate financial resources. Disbursement of funds for SIAs and payment of allowances to numerous vaccination personnel at the grassroots level are enormous operational challenges in a country the size of Nigeria. Upon donors' request for a transparent and effective payment mechanism, the World Health Organization (WHO), in consultation with national counterparts, created the innovative direct disbursement mechanism (DDM) in 2004. The objective of the DDM was to timely deploy operational funds at the field level and directly pay vaccination personnel allowances at the grassroots level. Methods. A detailed operational guideline for funds disbursement was developed in close consultation with central and field stakeholders. Multiyear financial resource requirements and operational budgets for every campaign were produced by an interagency-coordinated finance subcommittee. The WHO engaged a bank and an accounting firm as DDM partners to support disbursement of and accounting for the SIA funds, respectively. The 37 WHO field offices were equipped with electronic financial systems to support the DDM process, and temporary payment sites were set up to facilitate payment to vaccination personnel at the grassroots level. Coordination meetings among DDM partners were held regularly to reconcile financial records and address operational challenges. Results. Between 2004 and 2014, DDM supported 99 polio and nonpolio vaccination campaigns, disbursing more than $370 million to about 16 million beneficiaries across 280 temporary payment sites. To mitigate security risks and reduce operational costs, the WHO and DDM

  14. World Health Organization's Innovative Direct Disbursement Mechanism for Payment of Grassroots Immunization Personnel and Operations in Nigeria: 2004-2015.

    Science.gov (United States)

    Yehualashet, Yared G; Wadda, Alieu; Agblewonu, Koffi B; Zhema, Theophilus; Ibrahim, Al-Asi A; Corr, Alhagie; Linkins, Jennifer; Mkanda, Pascal; Vaz, Rui G; Nsubuga, Peter; Ashogbon, Daniel

    2016-05-01

    Following the 1988 World Health Assembly resolution to eradicate polio, the government of Nigeria, with support from partners, has been implementing several rounds of supplementary immunization activities (SIAs) each year. In addition to the technical requirements, the success of the polio eradication initiative depends on timely provision of adequate financial resources. Disbursement of funds for SIAs and payment of allowances to numerous vaccination personnel at the grassroots level are enormous operational challenges in a country the size of Nigeria. Upon donors' request for a transparent and effective payment mechanism, the World Health Organization (WHO), in consultation with national counterparts, created the innovative direct disbursement mechanism (DDM) in 2004. The objective of the DDM was to timely deploy operational funds at the field level and directly pay vaccination personnel allowances at the grassroots level. A detailed operational guideline for funds disbursement was developed in close consultation with central and field stakeholders. Multiyear financial resource requirements and operational budgets for every campaign were produced by an interagency-coordinated finance subcommittee. The WHO engaged a bank and an accounting firm as DDM partners to support disbursement of and accounting for the SIA funds, respectively. The 37 WHO field offices were equipped with electronic financial systems to support the DDM process, and temporary payment sites were set up to facilitate payment to vaccination personnel at the grassroots level. Coordination meetings among DDM partners were held regularly to reconcile financial records and address operational challenges. Between 2004 and 2014, DDM supported 99 polio and nonpolio vaccination campaigns, disbursing more than $370 million to about 16 million beneficiaries across 280 temporary payment sites. To mitigate security risks and reduce operational costs, the WHO and DDM partners introduced mobile payment to

  15. Mechanisms of direct inhibition of the respiratory sulfate-reduction pathway by (per)chlorate and nitrate.

    Science.gov (United States)

    Carlson, Hans K; Kuehl, Jennifer V; Hazra, Amrita B; Justice, Nicholas B; Stoeva, Magdalena K; Sczesnak, Andrew; Mullan, Mark R; Iavarone, Anthony T; Engelbrektson, Anna; Price, Morgan N; Deutschbauer, Adam M; Arkin, Adam P; Coates, John D

    2015-06-01

    We investigated perchlorate (ClO(4)(-)) and chlorate (ClO(3)(-)) (collectively (per)chlorate) in comparison with nitrate as potential inhibitors of sulfide (H(2)S) production by mesophilic sulfate-reducing microorganisms (SRMs). We demonstrate the specificity and potency of (per)chlorate as direct SRM inhibitors in both pure cultures and undefined sulfidogenic communities. We demonstrate that (per)chlorate and nitrate are antagonistic inhibitors and resistance is cross-inducible implying that these compounds share at least one common mechanism of resistance. Using tagged-transposon pools we identified genes responsible for sensitivity and resistance in Desulfovibrio alaskensis G20. We found that mutants in Dde_2702 (Rex), a repressor of the central sulfate-reduction pathway were resistant to both (per)chlorate and nitrate. In general, Rex derepresses its regulon in response to increasing intracellular NADH:NAD(+) ratios. In cells in which respiratory sulfate reduction is inhibited, NADH:NAD(+) ratios should increase leading to derepression of the sulfate-reduction pathway. In support of this, in (per)chlorate or nitrate-stressed wild-type G20 we observed higher NADH:NAD(+) ratios, increased transcripts and increased peptide counts for genes in the core Rex regulon. We conclude that one mode of (per)chlorate and nitrate toxicity is as direct inhibitors of the central sulfate-reduction pathway. Our results demonstrate that (per)chlorate are more potent inhibitors than nitrate in both pure cultures and communities, implying that they represent an attractive alternative for controlling sulfidogenesis in industrial ecosystems. Of these, perchlorate offers better application logistics because of its inhibitory potency, solubility, relative chemical stability, low affinity for mineral cations and high mobility in environmental systems.

  16. Probing neural mechanisms underlying auditory stream segregation in humans by transcranial direct current stimulation (tDCS).

    Science.gov (United States)

    Deike, Susann; Deliano, Matthias; Brechmann, André

    2016-10-01

    One hypothesis concerning the neural underpinnings of auditory streaming states that frequency tuning of tonotopically organized neurons in primary auditory fields in combination with physiological forward suppression is necessary for the separation of representations of high-frequency A and low-frequency B tones. The extent of spatial overlap between the tonotopic activations of A and B tones is thought to underlie the perceptual organization of streaming sequences into one coherent or two separate streams. The present study attempts to interfere with these mechanisms by transcranial direct current stimulation (tDCS) and to probe behavioral outcomes reflecting the perception of ABAB streaming sequences. We hypothesized that tDCS by modulating cortical excitability causes a change in the separateness of the representations of A and B tones, which leads to a change in the proportions of one-stream and two-stream percepts. To test this, 22 subjects were presented with ambiguous ABAB sequences of three different frequency separations (∆F) and had to decide on their current percept after receiving sham, anodal, or cathodal tDCS over the left auditory cortex. We could confirm our hypothesis at the most ambiguous ∆F condition of 6 semitones. For anodal compared with sham and cathodal stimulation, we found a significant decrease in the proportion of two-stream perception and an increase in the proportion of one-stream perception. The results demonstrate the feasibility of using tDCS to probe mechanisms underlying auditory streaming through the use of various behavioral measures. Moreover, this approach allows one to probe the functions of auditory regions and their interactions with other processing stages. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. Interconnection of thermal parameters, microstructure and mechanical properties in directionally solidified Sn–Sb lead-free solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Marcelino; Costa, Thiago [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil); Rocha, Otávio [Federal Institute of Education, Science and Technology of Pará — IFPA, 66093-020 Belém, PA (Brazil); Spinelli, José E. [Department of Materials Engineering, Federal University of São Carlos — UFSCar, 13565-905 São Carlos, SP (Brazil); Cheung, Noé, E-mail: cheung@fem.unicamp.br [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil); Garcia, Amauri [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil)

    2015-08-15

    Considerable effort is being made to develop lead-free solders for assembling in environmental-conscious electronics, due to the inherent toxicity of Pb. The search for substitute alloys of Pb–Sn solders has increased in order to comply with different soldering purposes. The solder must not only meet the expected levels of electrical performance but may also have appropriate mechanical strength, with the absence of cracks in the solder joints. The Sn–Sb alloy system has a range of compositions that can be potentially included in the class of high temperature solders. This study aims to establish interrelations of solidification thermal parameters, microstructure and mechanical properties of Sn–Sb alloys (2 wt.%Sb and 5.5 wt.%Sb) samples, which were directionally solidified under cooling rates similar to those of reflow procedures in industrial practice. A complete high-cooling rate cellular growth is shown to be associated with the Sn–2.0 wt.%Sb alloy and a reverse dendrite-to-cell transition is observed for the Sn–5.5 wt.%Sb alloy. Strength and ductility of the Sn–2.0 wt.%Sb alloy are shown not to be affected by the cellular spacing. On the other hand, a considerable variation in these properties is associated with the cellular region of the Sn–5.5 wt.%Sb alloy casting. - Graphical abstract: Display Omitted - Highlights: • The microstructure of the Sn–2 wt.%Sb alloy is characterized by high-cooling rates cells. • Reverse dendrite > cell transition occurs for Sn–5.5 wt.%Sb alloy: cells prevail for cooling rates > 1.2 K/s. • Sn–5.5 wt.%Sb alloy: the dendritic region occurs for cooling rates < 0.9 K/s. • Sn–5.5 wt.%Sb alloy: tensile properties are improved with decreasing cellular spacing.

  18. Kinetics and Mechanisms of Thiol–Disulfide Exchange Covering Direct Substitution and Thiol Oxidation-Mediated Pathways

    Science.gov (United States)

    2013-01-01

    Abstract Significance: Disulfides are important building blocks in the secondary and tertiary structures of proteins, serving as inter- and intra-subunit cross links. Disulfides are also the major products of thiol oxidation, a process that has primary roles in defense mechanisms against oxidative stress and in redox regulation of cell signaling. Although disulfides are relatively stable, their reduction, isomerisation, and interconversion as well as their production reactions are catalyzed by delicate enzyme machineries, providing a dynamic system in biology. Redox homeostasis, a thermodynamic parameter that determines which reactions can occur in cellular compartments, is also balanced by the thiol–disulfide pool. However, it is the kinetic properties of the reactions that best represent cell dynamics, because the partitioning of the possible reactions depends on kinetic parameters. Critical Issues: This review is focused on the kinetics and mechanisms of thiol–disulfide substitution and redox reactions. It summarizes the challenges and advances that are associated with kinetic investigations in small molecular and enzymatic systems from a rigorous chemical perspective using biological examples. The most important parameters that influence reaction rates are discussed in detail. Recent Advances and Future Directions: Kinetic studies of proteins are more challenging than small molecules, and quite often investigators are forced to sacrifice the rigor of the experimental approach to obtain the important kinetic and mechanistic information. However, recent technological advances allow a more comprehensive analysis of enzymatic systems via using the systematic kinetics apparatus that was developed for small molecule reactions, which is expected to provide further insight into the cell's machinery. Antioxid. Redox Signal. 18, 1623–1641. PMID:23075118

  19. Effect of pore architecture and stacking direction on mechanical properties of solid freeform fabrication-based scaffold for bone tissue engineering.

    Science.gov (United States)

    Lee, Jung-Seob; Cha, Hwang Do; Shim, Jin-Hyung; Jung, Jin Woo; Kim, Jong Young; Cho, Dong-Woo

    2012-07-01

    Fabrication of a three-dimensional (3D) scaffold with increased mechanical strength may be an essential requirement for more advanced bone tissue engineering scaffolds. Various material- and chemical-based approaches have been explored to enhance the mechanical properties of engineered bone tissue scaffolds. In this study, the effects of pore architecture and stacking direction on the mechanical and cell proliferation properties of a scaffold were investigated. The 3D scaffold was prepared using solid freeform fabrication technology with a multihead deposition system. Various types of scaffolds with different pore architectures (lattice, stagger, and triangle types) and stacking directions (horizontal and vertical directions) were fabricated with a blend of polycaprolactone and poly lactic-co-glycolic acid. In compression tests, the triangle-type scaffold was the strongest among the experimental groups. Stacking direction affected the mechanical properties of scaffolds. An in vitro cell counting kit-8 assay showed no significant differences in optical density depending on the different pore architectures and stacking directions. In conclusion, mechanical properties of scaffolds can be enhanced by controlling pore architecture and stacking direction. Copyright © 2012 Wiley Periodicals, Inc.

  20. Direct measures of mechanical energy for knife mill size reduction of switchgrass, wheat straw, and corn stover.

    Science.gov (United States)

    Bitra, Venkata S P; Womac, Alvin R; Igathinathane, C; Miu, Petre I; Yang, Yuechuan T; Smith, David R; Chevanan, Nehru; Sokhansanj, Shahab

    2009-12-01

    Lengthy straw/stalk of biomass may not be directly fed into grinders such as hammer mills and disc refiners. Hence, biomass needs to be preprocessed using coarse grinders like a knife mill to allow for efficient feeding in refiner mills without bridging and choking. Size reduction mechanical energy was directly measured for switchgrass (Panicum virgatum L.), wheat straw (Triticum aestivum L.), and corn stover (Zea mays L.) in an instrumented knife mill. Direct power inputs were determined for different knife mill screen openings from 12.7 to 50.8 mm, rotor speeds between 250 and 500 rpm, and mass feed rates from 1 to 11 kg/min. Overall accuracy of power measurement was calculated to be +/-0.003 kW. Total specific energy (kWh/Mg) was defined as size reduction energy to operate mill with biomass. Effective specific energy was defined as the energy that can be assumed to reach the biomass. The difference is parasitic or no-load energy of mill. Total specific energy for switchgrass, wheat straw, and corn stover chopping increased with knife mill speed, whereas, effective specific energy decreased marginally for switchgrass and increased for wheat straw and corn stover. Total and effective specific energy decreased with an increase in screen size for all the crops studied. Total specific energy decreased with increase in mass feed rate, but effective specific energy increased for switchgrass and wheat straw, and decreased for corn stover at increased feed rate. For knife mill screen size of 25.4 mm and optimum speed of 250 rpm, optimum feed rates were 7.6, 5.8, and 4.5 kg/min for switchgrass, wheat straw, and corn stover, respectively, and the corresponding total specific energies were 7.57, 10.53, and 8.87 kWh/Mg and effective specific energies were 1.27, 1.50, and 0.24 kWh/Mg for switchgrass, wheat straw, and corn stover, respectively. Energy utilization ratios were calculated as 16.8%, 14.3%, and 2.8% for switchgrass, wheat straw, and corn stover, respectively. These

  1. Direct Renin Inhibition with Aliskiren Improves Ischemia-Induced Neovasculogenesis in Diabetic Animals via the SDF-1 Related Mechanism.

    Directory of Open Access Journals (Sweden)

    Ting-Ting Chang

    Full Text Available Aliskiren is a direct renin inhibitor which is suggested to modify proangiogenic cells in addition to lower blood pressure. Given that angiogenesis is impaired in the presence of diabetes mellitus, we would like to investigate whether and how aliskiren enhances endothelial progenitor cells (EPCs and improves ischemic-induced neovasculogenesis by an effect independent of blood pressure reduction in diabetic animals.Streptozotocin-induced diabetic mice were administered with either aliskiren (5 or 25 mg/kg/day using an osmotic pump or hydralazine (2 or 10 mg/kg/day given in drinking water for two weeks prior to a hind-limb ischemia surgery. Laser Doppler imaging and flow cytometry were used to evaluate the degree of neovasculogenesis and the circulating levels of EPCs, respectively.In streptozotocin-induced diabetic mice, aliskiren enhanced the recovery of limb perfusion and capillary density, increased the number of circulating Sca-1+/Flk-1+ EPC-like cells, and elevated the levels of the plasma vascular endothelial growth factor (VEGF and stromal cell-derived factor (SDF-1α in a dose-dependent manner, whereas there were no such effects in hydralazine-treated mice. Intraperitoneal administration of anti-SDF-1 neutralizing monoclonal antibodies abolished the effects of aliskiren.Independent of the reduction of blood pressure, aliskiren enhanced ischemia-induced neovasculogenesis in a dose-dependent manner via VEGF/SDF-1α related mechanisms in diabetic mice.

  2. Reliable and cost effective design of intermetallic Ni2Si nanowires and direct characterization of its mechanical properties.

    Science.gov (United States)

    Han, Seung Zeon; Kang, Joonhee; Kim, Sung-Dae; Choi, Si-Young; Kim, Hyung Giun; Lee, Jehyun; Kim, Kwangho; Lim, Sung Hwan; Han, Byungchan

    2015-10-12

    We report that a single crystal Ni2Si nanowire (NW) of intermetallic compound can be reliably designed using simple three-step processes: casting a ternary Cu-Ni-Si alloy, nucleate and growth of Ni2Si NWs as embedded in the alloy matrix via designing discontinuous precipitation (DP) of Ni2Si nanoparticles and thermal aging, and finally chemical etching to decouple the Ni2Si NWs from the alloy matrix. By direct application of uniaxial tensile tests to the Ni2Si NW we characterize its mechanical properties, which were rarely reported in previous literatures. Using integrated studies of first principles density functional theory (DFT) calculations, high-resolution transmission electron microscopy (HRTEM), and energy-dispersive X-ray spectroscopy (EDX) we accurately validate the experimental measurements. Our results indicate that our simple three-step method enables to design brittle Ni2Si NW with high tensile strength of 3.0 GPa and elastic modulus of 60.6 GPa. We propose that the systematic methodology pursued in this paper significantly contributes to opening innovative processes to design various kinds of low dimensional nanomaterials leading to advancement of frontiers in nanotechnology and related industry sectors.

  3. Analysis of the flexible support mechanisms in the Directive on the promotion of the use of energy from renewable sources. Final report 8th January 2010

    Energy Technology Data Exchange (ETDEWEB)

    Ruokonen, J.; Sinnemaa, M.A.; Magnusson, R.; Gautesen, K.; Seppaenen, S.; Opsal, O.

    2010-07-01

    The Nordic countries have a long history in co-operation and a common electricity market. The long-term objective of Nordic countries is to promote an efficient, competitive, secure and sustainable energy supply. The EU countries have set a binding target to increase the share of renewable energy to 20% by 2020. The European Parliament approved a legislative resolution on December 17th 2008 on the proposal for a Directive on the promotion of the use of energy from renewable source ('The Directive'). This Directive become part of the European Community legislation in 2009. The Directive sets national targets for renewable energy, but it also provides various flexibility mechanisms that enable co-operation between countries in reaching the national targets. It is however still not clear how these flexible mechanisms should be used, nor the consequences on the electricity market and renewable energy sources. The objective of this project is to evaluate the usefulness and consequences of utilising the Flexible Mechanisms described in the Articles 6-11 ('Flex-Mex') of the Directive in Nordic Countries. Moreover, the objective is to provide basis for conclusions and political recommendations on whether and how to cooperate and move forward in this area. In addition to basic principles of the flexible mechanisms, the project concentrates on analysing the arrangements needed between the Nordic Countries to utilise the flexible mechanisms and analysis of benefits and problems of using Mechanisms. The report is divided five sections. Chapter 2 introduced the RES directive and Flexible Mechanisms. In chapter 3, lesson learnt from other markets are used as starting point in drawing possible frameworks for Nordic countries. Chapter 4 summarizes presents outcome of various co-operation scenarios and their benefits. In Chapter 5 some selected topics are discussed from RES Flex-Mex point of view. Chapter 6 provides conclusions and recommendations. (Author)

  4. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  5. The Neuro-Mechanical Processes That Underlie Goal-Directed Medio-Lateral APA during Gait Initiation.

    Science.gov (United States)

    Honeine, Jean-Louis; Schieppati, Marco; Crisafulli, Oscar; Do, Manh-Cuong

    2016-01-01

    Gait initiation (GI) involves passing from bipedal to unipedal stance. It requires a rapid movement of the center of foot pressure (CoP) towards the future swing foot and of the center of mass (CoM) in the direction of the stance foot prior to the incoming step. This anticipatory postural adjustment (APA) allows disengaging the swing leg from the ground and establishing favorable conditions for stepping. This study aimed to describe the neuro-mechanical process that underlies the goal-directed medio-lateral (ML) APA. We hypothesized that controlled knee flexion of the stance leg contributes to the initial ML displacement of the CoP and to the calibration of the first step. Fourteen subjects initiated gait starting from three different initial stance widths of 15 cm (Small), 30 cm (Medium), and 45 cm (Large). Optoelectronic, force platform and electromyogram (EMG) measurements were performed. During APA, soleus activity diminished bilaterally, while tibialis anterior (TA) activity increased, more so in the stance leg than in the swing leg, and to a larger extent with increasing initial stance width. Knee flexion of the stance leg was observed during APA and correlated with the ML CoP displacement towards the swing leg. ML CoP and CoM displacements during APA increased with increasing stance width. The activity of stance-leg TA was correlated with the degree of knee flexion. Swing-leg tensor fasciae latae (TFL) was also active during APA. Across subjects, when stance-leg tibialis activity was low, TFL activity was large and vice versa. The modulation of the ML CoP position during APA allowed the gravity-driven torque to place the CoM just lateral to the stance foot during step execution. Accordingly, the gravity-driven torque, the ML CoM velocity during step execution, and the step width at foot contact (FC) were lower in the Small and greater in the Large condition. Consequently, the position of the stepping foot at FC remained close to the sagittal plane in all

  6. Dissecting the Catalytic Mechanism of Betaine-Homocysteine S-Methyltransferase Using Intrinsic Tryptophan Fluorescence and Site-Directed Mutagenesis

    Energy Technology Data Exchange (ETDEWEB)

    Castro, C.; Gratson, A.A.; Evans, J.C.; Jiracek, J.; Collinsova, M.; Ludwig, M.L.; Garrow, T.A. (ASCR); (UIUC); (Michigan)

    2010-03-05

    Betaine-homocysteine S-methyltransferase (BHMT) is a zinc-dependent enzyme that catalyzes the transfer of a methyl group from glycine betaine (Bet) to homocysteine (Hcy) to form dimethylglycine (DMG) and methionine (Met). Previous studies in other laboratories have indicated that catalysis proceeds through the formation of a ternary complex, with a transition state mimicked by the inhibitor S-({delta}-carboxybutyl)-l-homocysteine (CBHcy). Using changes in intrinsic tryptophan fluorescence to determine the affinity of human BHMT for substrates, products, or CBHcy, we now demonstrate that the enzyme-substrate complex reaches its transition state through an ordered bi-bi mechanism in which Hcy is the first substrate to bind and Met is the last product released. Hcy, Met, and CBHcy bind to the enzyme to form binary complexes with K{sub d} values of 7.9, 6.9, and 0.28 {micro}M, respectively. Binary complexes with Bet and DMG cannot be detected with fluorescence as a probe, but Bet and DMG bind tightly to BHMT-Hcy to form ternary complexes with K{sub d} values of 1.1 and 0.73 {micro}M, respectively. Mutation of each of the seven tryptophan residues in human BHMT provides evidence that the enzyme undergoes two distinct conformational changes that are reflected in the fluorescence of the enzyme. The first is induced when Hcy binds, and the second, when Bet binds. As predicted by the crystal structure of BHMT, the amino acids Trp44 and Tyr160 are involved in binding Bet, and Glu159 in binding Hcy. Replacing these residues by site-directed mutagenesis significantly reduces the catalytic efficiency (V{sub max}/K{sub m}) of the enzyme. Replacing Tyr77 with Phe abolishes enzyme activity.

  7. Physical activity and self-esteem: testing direct and indirect relationships associated with psychological and physical mechanisms.

    Science.gov (United States)

    Zamani Sani, Seyed Hojjat; Fathirezaie, Zahra; Brand, Serge; Pühse, Uwe; Holsboer-Trachsler, Edith; Gerber, Markus; Talepasand, Siavash

    2016-01-01

    In the present study, we investigated the relationship between physical activity (PA) and self-esteem (SE), while introducing body mass index (BMI), perceived physical fitness (PPF), and body image (BI) in adults (N =264, M =38.10 years). The findings indicated that PA was directly and indirectly associated with SE. BMI predicted SE neither directly nor indirectly, but was directly associated with PPF and both directly and indirectly with BI. Furthermore, PPF was directly related to BI and SE, and a direct association was found between BI and SE. The pattern of results suggests that among a sample of adults, PA is directly and indirectly associated with SE, PPF, and BI, but not with BMI. PA, PPF, and BI appear to play an important role in SE. Accordingly, regular PA should be promoted, in particular, among adults reporting lower SE.

  8. 3-D simulation of soot formation in a direct-injection diesel engine based on a comprehensive chemical mechanism and method of moments

    Science.gov (United States)

    Zhong, Bei-Jing; Dang, Shuai; Song, Ya-Na; Gong, Jing-Song

    2012-02-01

    Here, we propose both a comprehensive chemical mechanism and a reduced mechanism for a three-dimensional combustion simulation, describing the formation of polycyclic aromatic hydrocarbons (PAHs), in a direct-injection diesel engine. A soot model based on the reduced mechanism and a method of moments is also presented. The turbulent diffusion flame and PAH formation in the diesel engine were modelled using the reduced mechanism based on the detailed mechanism using a fixed wall temperature as a boundary condition. The spatial distribution of PAH concentrations and the characteristic parameters for soot formation in the engine cylinder were obtained by coupling a detailed chemical kinetic model with the three-dimensional computational fluid dynamic (CFD) model. Comparison of the simulated results with limited experimental data shows that the chemical mechanisms and soot model are realistic and correctly describe the basic physics of diesel combustion but require further development to improve their accuracy.

  9. Investigation of the direct runoff generation mechanism for the analysis of the SCS-CN method applicability to a partial area experimental watershed

    OpenAIRE

    Soulis, K. X.; Valiantzas, J. D.; Dercas, N.; Londra, P. A.

    2009-01-01

    The Soil Conservation Service Curve Number (SCS-CN) method is widely used for predicting direct runoff volume for a given rainfall event. The applicability of the SCS-CN method and the direct runoff generation mechanism were thoroughly analysed in a Mediterranean experimental watershed in Greece. The region is characterized by a Mediterranean semi-arid climate. A detailed land cover and soil survey using remote sensing and GIS techniques, showed that the watershed is dominated by coarse soils...

  10. Thermal and Mechanical Non-Equilibrium Effects on Turbulent Flows: Fundamental Studies of Energy Exchanges Through Direct Numerical Simulations, Molecular Simulations and Experiments

    Science.gov (United States)

    2016-02-26

    photochemical TNE generation, and chemistry of non- equilibrium phenomena. We have investigated a new concept to generate turbulence using photo-initiated...AFRL-AFOSR-VA-TR-2016-0104 Thermal and mechanical non- equilibrium effects on turbulent flows:fundamental studies of energy exchanges through direct...Performance 3. DATES COVERED (From - To) 15-09-2012 to 14-11-2015 4. TITLE AND SUBTITLE Thermal and mechanical non- equilibrium effects on turbulent

  11. Computational mechanics - Advances and trends; Proceedings of the Session - Future directions of Computational Mechanics of the ASME Winter Annual Meeting, Anaheim, CA, Dec. 7-12, 1986

    Science.gov (United States)

    Noor, Ahmed K. (Editor)

    1986-01-01

    The papers contained in this volume provide an overview of the advances made in a number of aspects of computational mechanics, identify some of the anticipated industry needs in this area, discuss the opportunities provided by new hardware and parallel algorithms, and outline some of the current government programs in computational mechanics. Papers are included on advances and trends in parallel algorithms, supercomputers for engineering analysis, material modeling in nonlinear finite-element analysis, the Navier-Stokes computer, and future finite-element software systems.

  12. The Commission's proposal for a Directive on Double Taxation Dispute Resolution Mechanisms:Overcoming the final hurdle of juridical double taxation within the European Union?

    OpenAIRE

    Cerioni, Luca

    2017-01-01

    This article examines the Commission’s proposal for a Directive on Double Taxation Dispute Resolution Mechanisms, by highlighting interpretative issues that its wording may arise and by discussing the conditions under which it could manage to lead to the elimination of (juridical) double taxation within the EU.

  13. Mechanically stable, hierarchically porous Cu3(btc)2 (HKUST-1) monoliths via direct conversion of copper(II) hydroxide-based monoliths.

    Science.gov (United States)

    Moitra, Nirmalya; Fukumoto, Shotaro; Reboul, Julien; Sumida, Kenji; Zhu, Yang; Nakanishi, Kazuki; Furukawa, Shuhei; Kitagawa, Susumu; Kanamori, Kazuyoshi

    2015-02-28

    The synthesis of highly crystalline macro-meso-microporous monolithic Cu3(btc)2 (HKUST-1; btc(3-) = benzene-1,3,5-tricarboxylate) is demonstrated by direct conversion of Cu(OH)2-based monoliths while preserving the characteristic macroporous structure. The high mechanical strength of the monoliths is promising for possible applications to continuous flow reactors.

  14. Physical activity and self-esteem: testing direct and indirect relationships associated with psychological and physical mechanisms

    Directory of Open Access Journals (Sweden)

    Zamani Sani SH

    2016-10-01

    Full Text Available Seyed Hojjat Zamani Sani,1 Zahra Fathirezaie,1 Serge Brand,2 Uwe Pühse,3 Edith Holsboer-Trachsler,2 Markus Gerber,3 Siavash Talepasand4 1Department of Motor Behavior, Faculty of Physical Education and Sport Science, University of Tabriz, Tabriz, Iran; 2Psychiatric Clinics of the University of Basel, Center for Affective, Stress and Sleep Disorders (ZASS, 3Department of Sport, Exercise and Health, Sport Science Section, University of Basel, Basel, Switzerland; 4Department of Psychology and Educational Sciences, Semnan University, Semnan, Iran Abstract: In the present study, we investigated the relationship between physical activity (PA and self-esteem (SE, while introducing body mass index (BMI, perceived physical fitness (PPF, and body image (BI in adults (N =264, M =38.10 years. The findings indicated that PA was directly and indirectly associated with SE. BMI predicted SE neither directly nor indirectly, but was directly associated with PPF and both directly and indirectly with BI. Furthermore, PPF was directly related to BI and SE, and a direct association was found between BI and SE. The pattern of results suggests that among a sample of adults, PA is directly and indirectly associated with SE, PPF, and BI, but not with BMI. PA, PPF, and BI appear to play an important role in SE. Accordingly, regular PA should be promoted, in particular, among adults reporting lower SE. Keywords: physical activity, self-esteem, physical fitness, body image, adults

  15. Modelling of Mechanical Behavior at High Strain Rate of Ti-6al-4v Manufactured By Means of Direct Metal Laser Sintering Technique

    Science.gov (United States)

    Iannitti, Gianluca; Bonora, Nicola; Gentile, Domenico; Ruggiero, Andrew; Testa, Gabriel; Gubbioni, Simone

    2017-06-01

    In this work, the mechanical behavior of Ti-6Al-4V obtained by additive manufacturing technique was investigated, also considering the build direction. Dog-bone shaped specimens and Taylor cylinders were machined from rods manufactured by means of the EOSSINT M2 80 machine, based on Direct Metal Laser Sintering technique. Tensile tests were performed at strain rate ranging from 5E-4 s-1 to 1000 s-1 using an Instron electromechanical machine for quasistatic tests and a Direct-Tension Split Hopkinson Bar for dynamic tests. The mechanical strength of the material was described by a Johnson-Cook model modified to account for stress saturation occurring at high strain. Taylor cylinder tests and their corresponding numerical simulations were carried out in order to validate the constitutive model under a complex deformation path, high strain rates, and high temperatures.

  16. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  17. Enantioselective Direct α-Amination of Aldehydes via a Photoredox Mechanism: A Strategy for Asymmetric Amine Fragment Coupling

    OpenAIRE

    Cecere, Giuseppe; Koenig, Christian M.; Alleva, Jennifer L.; MacMillan, David W. C.

    2013-01-01

    The direct, asymmetric α-amination of aldehydes has been accomplished via a combination of photoredox and organocatalysis. Photon-generated, nitrogen-centered radicals undergo enantioselective α-addition to catalytically formed chiral enamines to directly produce stable α-amino aldehyde adducts bearing synthetically useful amine substitution patterns. Incorporation of a photolabile group on the amine precursor obviates the need to employ a photoredox catalyst in this transformation. Important...

  18. Numerical study of turbulence-influence mechanism on arc characteristics in an air direct current circuit breaker

    Science.gov (United States)

    Wu, Mingliang; Yang, Fei; Rong, Mingzhe; Wu, Yi; Qi, Yang; Cui, Yufei; Liu, Zirui; Guo, Anxiang

    2016-04-01

    This paper focuses on the numerical investigation of arc characteristics in an air direct current circuit breaker (air DCCB). Using magneto-hydrodynamics (MHD) theory, 3D laminar model and turbulence model are constructed and calculated. The standard k-epsilon model is utilized to consider the turbulence effect in the arc chamber of the DCCB. Several important phenomena are found: the arc column in the turbulence-model case is more extensive, moves much more slowly than the counterpart in the laminar-model case, and shows stagnation at the entrance of the chamber, unlike in the laminar-model case. Moreover, the arc voltage in the turbulence-model case is much lower than in the laminar-model case. However, the results in the turbulence-model case show a much better agreement with the results of the breaking experiments under DC condition than in the laminar-model case, which is contradictory to the previous conclusions from the arc researches of both the low-voltage circuit breaker and the sulfur hexafluoride (SF6) nozzle. First, in the previous air-arc research of the low-voltage circuit breaker, it is assumed that the air plasma inside the chamber is in the state of laminar, and the laminar-model application gives quite satisfactory results compared with the experiments, while in this paper, the laminar-model application works badly. Second, the turbulence-model application in the arc research of the SF6-nozzle performs much better and gives higher arc voltage than the laminar-model application does, whereas in this paper, the turbulence-model application predicts lower arc voltage than the laminar-model application does. Based on the analysis of simulation results in detail, the mechanism of the above phenomena is revealed. The transport coefficients are strongly changed by turbulence, which will enhance the arc diffusion and make the arc volume much larger. Consequently, the arc appearance and the distribution of Lorentz force in the turbulence-model case

  19. Numerical study of turbulence-influence mechanism on arc characteristics in an air direct current circuit breaker

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Mingliang; Yang, Fei, E-mail: yfei2007@mail.xjtu.edu.cn; Rong, Mingzhe; Wu, Yi; Qi, Yang; Cui, Yufei [State Key Lab of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi' an Jiaotong University, Xi' an Shaanxi 710049 (China); Liu, Zirui [State Grid Shaanxi Electric Power Company, Xi' an, Shaanxi (China); Guo, Anxiang [Electric Power Research Institute of State Grid Shaanxi Electric Power Company, Xi' an, Shaanxi (China)

    2016-04-15

    This paper focuses on the numerical investigation of arc characteristics in an air direct current circuit breaker (air DCCB). Using magneto-hydrodynamics (MHD) theory, 3D laminar model and turbulence model are constructed and calculated. The standard k-epsilon model is utilized to consider the turbulence effect in the arc chamber of the DCCB. Several important phenomena are found: the arc column in the turbulence-model case is more extensive, moves much more slowly than the counterpart in the laminar-model case, and shows stagnation at the entrance of the chamber, unlike in the laminar-model case. Moreover, the arc voltage in the turbulence-model case is much lower than in the laminar-model case. However, the results in the turbulence-model case show a much better agreement with the results of the breaking experiments under DC condition than in the laminar-model case, which is contradictory to the previous conclusions from the arc researches of both the low-voltage circuit breaker and the sulfur hexafluoride (SF6) nozzle. First, in the previous air-arc research of the low-voltage circuit breaker, it is assumed that the air plasma inside the chamber is in the state of laminar, and the laminar-model application gives quite satisfactory results compared with the experiments, while in this paper, the laminar-model application works badly. Second, the turbulence-model application in the arc research of the SF6-nozzle performs much better and gives higher arc voltage than the laminar-model application does, whereas in this paper, the turbulence-model application predicts lower arc voltage than the laminar-model application does. Based on the analysis of simulation results in detail, the mechanism of the above phenomena is revealed. The transport coefficients are strongly changed by turbulence, which will enhance the arc diffusion and make the arc volume much larger. Consequently, the arc appearance and the distribution of Lorentz force in the turbulence-model case

  20. An on-line modelling study of the direct effect of atmospheric aerosols over Europe

    International Nuclear Information System (INIS)

    Palacios, L.; Baro, R.; Jimenez-Guerrero, P.

    2015-01-01

    Atmospheric aerosols affect human health, ecosystems, materials, visibility and Earth’s climate. Those effects are studied in this present work and depend mainly on the aerosol optical properties and how they influence the Earth’s radiation budget. Such properties can be divided on direct and semi-direct effect, produced by the scattering and absorption of radiation; and indirect effect, which influences the aerosols-cloud interactions. The aim of this work is to assess the direct effect through the study of the mean temperature; the radiation that reaches the Earth’s surface and at the top of the atmosphere; and the interaction of these meteorological variables with particulate matter (PM10). Results indicate decreases in temperature and radiation that reaches the Earth's surface, together with increases in the outgoing radiation at top of the atmosphere, and changes in the particulate matter, thus proving a colder climate due to the direct effect of atmospheric aerosols. (Author)

  1. An on-line modelling study of the direct effect of atmospheric aerosols over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, L.; Baro, R.; Jimenez-Guerrero, P.

    2015-07-01

    Atmospheric aerosols affect human health, ecosystems, materials, visibility and Earth’s climate. Those effects are studied in this present work and depend mainly on the aerosol optical properties and how they influence the Earth’s radiation budget. Such properties can be divided on direct and semi-direct effect, produced by the scattering and absorption of radiation; and indirect effect, which influences the aerosols-cloud interactions. The aim of this work is to assess the direct effect through the study of the mean temperature; the radiation that reaches the Earth’s surface and at the top of the atmosphere; and the interaction of these meteorological variables with particulate matter (PM10). Results indicate decreases in temperature and radiation that reaches the Earth's surface, together with increases in the outgoing radiation at top of the atmosphere, and changes in the particulate matter, thus proving a colder climate due to the direct effect of atmospheric aerosols. (Author)

  2. An on-line modelling study of the direct effect of atmospheric aerosols over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, L.; Baro, R.; Jimenez-Guerrero, P.

    2015-07-01

    Atmospheric aerosols affect human health, ecosystems, materials, visibility and Earths climate. Those effects are studied in this present work and depend mainly on the aerosol optical properties and how they influence the Earths radiation budget. Such properties can be divided on direct and semi-direct effect, produced by the scattering and absorption of radiation; and indirect effect, which influences the aerosols-cloud interactions. The aim of this work is to assess the direct effect through the study of the mean temperature; the radiation that reaches the Earths surface and at the top of the atmosphere; and the interaction of these meteorological variables with particulate matter (PM10). Results indicate decreases in temperature and radiation that reaches the Earth's surface, together with increases in the outgoing radiation at top of the atmosphere, and changes in the particulate matter, thus proving a colder climate due to the direct effect of atmospheric aerosols. (Author)

  3. Direct Democracy

    DEFF Research Database (Denmark)

    Beramendi, Virginia; Ellis, Andrew; Kaufman, Bruno

    While many books on direct democracy have a regional or national approach, or simply focus on one of the many mechanisms associated with direct democracy, this Handbook delves into a global comparison of direct democracy mechanisms, including referendums, citizens' initiatives, agenda initiatives...... learned. In addition, the uniquely comprehensive world survey outlines direct democracy provisions in 214 countries and territories and indicates which, if any, of these provisions are used by each country or territory at both the national and sub-national levels. Furthermore, the world survey includes...

  4. A Direct Test of the Differentiation Mechanism: REM, BCDMEM, and the Strength-Based Mirror Effect in Recognition Memory

    Science.gov (United States)

    Starns, Jeffrey J.; White, Corey N.; Ratcliff, Roger

    2010-01-01

    We explore competing explanations for the reduction in false alarm rate observed when studied items are strengthened. Some models, such as Retrieving Effectively from Memory (REM; Shiffrin & Steyvers, 1997), attribute the false alarm rate reduction to differentiation, a process in which strengthening memory traces at study directly reduces the…

  5. Quasi-fluid-mechanics-based quasi-Bayesian Cramer-Rao bounds for deformed towed-array direction finding

    Czech Academy of Sciences Publication Activity Database

    Tichavský, Petr; Wong, K. T.

    2004-01-01

    Roč. 52, č. 1 (2004), s. 36-47 ISSN 1053-587X R&D Projects: GA ČR GA102/01/0021 Institutional research plan: CEZ:AV0Z1075907 Keywords : array signal processing * direction-of-arrival estimation * marine telemetry Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.755, year: 2004

  6. Effects of build direction on the mechanical properties of 3D-printed complete coverage interim dental restorations

    NARCIS (Netherlands)

    Alharbi, N.; Osman, R.; Wismeijer, D.

    2016-01-01

    Statement of problem. The application of 3-dimensional printing technology is emerging in dentistry and is being increasingly used to fabricate dental restorations. To date, scientific evidence is lacking regarding the effect of different factors on the mechanical properties of the printed

  7. Degradation mechanism of Direct Pink 12B treated by iron-carbon micro-electrolysis and Fenton reaction.

    Science.gov (United States)

    Wang, Xiquan; Gong, Xiaokang; Zhang, Qiuxia; Du, Haijuan

    2013-12-01

    The Direct Pink 12B dye was treated by iron-carbon micro-electrolysis (ICME) and Fenton oxidation. The degradation pathway of Direct Pink 12B dye was inferred by ultraviolet visible (UV-Vis), infrared absorption spectrum (IR) and high performance liquid chromatography-mass spectrometry (HPLC-MS). The major reason of decolorization was that the conjugate structure was disrupted in the iron-carbon micro-electrolysis (ICME) process. However, the dye was not degraded completely because benzene rings and naphthalene rings were not broken. In the Fenton oxidation process, the azo bond groups surrounded by higher electron cloud density were first attacked by hydroxyl radicals to decolorize the dye molecule. Finally benzene rings and naphthalene rings were mineralized to H2O and CO2 under the oxidation of hydroxyl radicals. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  8. A new hypothesis on the simultaneous direct and indirect proton pump mechanisms in NADH-quinone oxidoreductase (complex I).

    Science.gov (United States)

    Ohnishi, Tomoko; Nakamaru-Ogiso, Eiko; Ohnishi, S Tsuyoshi

    2010-10-08

    Recently, Sazanov's group reported the X-ray structure of whole complex I [Nature, 465, 441 (2010)], which presented a strong clue for a "piston-like" structure as a key element in an "indirect" proton pump. We have studied the NuoL subunit which has a high sequence similarity to Na(+)/H(+) antiporters, as do the NuoM and N subunits. We constructed 27 site-directed NuoL mutants. Our data suggest that the H(+)/e(-) stoichiometry seems to have decreased from (4H(+)/2e(-)) in the wild-type to approximately (3H(+)/2e(-)) in NuoL mutants. We propose a revised hypothesis that each of the "direct" and the "indirect" proton pumps transports 2H(+) per 2e(-). Copyright © 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  9. Seeing the same thing differently: mechanisms that contribute to assessor differences in directly-observed performance assessments.

    Science.gov (United States)

    Yeates, Peter; O'Neill, Paul; Mann, Karen; Eva, Kevin

    2013-08-01

    Assessors' scores in performance assessments are known to be highly variable. Attempted improvements through training or rating format have achieved minimal gains. The mechanisms that contribute to variability in assessors' scoring remain unclear. This study investigated these mechanisms. We used a qualitative approach to study assessors' judgements whilst they observed common simulated videoed performances of junior doctors obtaining clinical histories. Assessors commented concurrently and retrospectively on performances, provided scores and follow-up interviews. Data were analysed using principles of grounded theory. We developed three themes that help to explain how variability arises: Differential Salience-assessors paid attention to (or valued) different aspects of the performances to different degrees; Criterion Uncertainty-assessors' criteria were differently constructed, uncertain, and were influenced by recent exemplars; Information Integration-assessors described the valence of their comments in their own unique narrative terms, usually forming global impressions. Our results (whilst not precluding the operation of established biases) describe mechanisms by which assessors' judgements become meaningfully-different or unique. Our results have theoretical relevance to understanding the formative educational messages that performance assessments provide. They give insight relevant to assessor training, assessors' ability to be observationally "objective" and to the educational value of narrative comments (in contrast to numerical ratings).

  10. Trojan-horse mechanism in the cellular uptake of silver nanoparticles verified by direct intra- and extracellular silver speciation analysis.

    Science.gov (United States)

    Hsiao, I-Lun; Hsieh, Yi-Kong; Wang, Chu-Fang; Chen, I-Chieh; Huang, Yuh-Jeen

    2015-03-17

    The so-called "Trojan-horse" mechanism, in which nanoparticles are internalized within cells and then release high levels of toxic ions, has been proposed as a behavior in the cellular uptake of Ag nanoparticles (AgNPs). While several reports claim to have proved this mechanism by measuring AgNPs and Ag ions (I) in cells, it cannot be fully proven without examining those two components in both intra- and extracellular media. In our study, we found that even though cells take up AgNPs similarly to (microglia (BV-2)) or more rapidly than (astrocyte (ALT)) Ag (I), the ratio of AgNPs to total Ag (AgNPs+Ag (I)) in both cells was lower than that in outside media. It could be explained that H2O2, a major intracellular reactive oxygen species (ROS), reacts with AgNPs to form more Ag (I). Moreover, the major speciation of Ag (I) in cells was Ag(cysteine) and Ag(cysteine)2, indicating the possible binding of monomer cysteine or vital thiol proteins/peptides to Ag ions. Evidence we found indicates that the Trojan-horse mechanism really exists.

  11. Understanding the mechanism of direct electrochemistry of mitochondria-modified electrodes from yeast, potato and bovine sources at carbon paper electrodes

    International Nuclear Information System (INIS)

    Giroud, Fabien; Nicolo, Tera A.; Koepke, Sara J.; Minteer, Shelley D.

    2013-01-01

    Although mitochondria have been used for bio-electrochemistry for over 5 years, little is known about their direct electrochemistry mechanism. This paper focuses on developing a better understanding of the electron transfer mechanism of mitochondria from three different organisms at carbon electrodes. Yeast, potato and bovine mitochondria have been successfully isolated and immobilized onto Toray paper electrodes via vapor deposited silica. Organelle-modified electrodes were first characterized using cyclic voltammetry. Similar electrochemical signals were obtained for all organisms. Direct electron transfer was observed when a metabolite of the Krebs cycle was present in the buffer solution. Control experiments based on the immobilization of two electron carriers contained in mitochondria, cytochrome c and a quinone (coenzyme Q 10 ), tend to show the electron transfer mechanism to the carbon material comes from the quinone pool of the organelles. As quinones are known to be pH-dependent, we further investigated the response of the electrochemical signal of the three isolated mitochondria and the two electron carriers separately. The half wave potentials obtained from the organelles appeared to be pH-dependent and their variations are comparable to coenzyme Q 10 rather than cytochrome c. Finally, extraction of both the cytochrome c and the quinone pool from intact mitochondria was performed to validate our hypothesis that direct electrochemistry of mitochondria happens via the quinone pool. Electrochemistry of immobilized quinone-depleted mitochondria validated the hypothesis that the mitochondria are communicating with the electrodes through the quinone pool

  12. Microstructures and mechanical properties of 3D 4-directional, C{sub f}/ZrC–SiC composites using ZrC precursor and polycarbosilane

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qinggang, E-mail: liqinggang66@gmail.com [School of Material Science and Engineering, University of Jinan, Jinan 250022 (China); Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, Jinan 250022 (China); Dong, Shaoming [Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Zhi; Shi, Guopu; Ma, Yan [School of Material Science and Engineering, University of Jinan, Jinan 250022 (China); Zhou, Haijun; Wang, Zhen; He, Ping [Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2013-11-01

    Highlights: • Three-dimensional 4-directional C{sub f}/ZrC–SiC composites fabricated by polymer infiltration and pyrolysis. • The microstructure and mechanical properties of the composites were studied. • High-temperature oxidation resistance and anti-ablation properties were evaluated. • Results show the composites have good mechanical and excellent ablative properties. -- Abstract: Three-dimensional 4-directional C{sub f}/ZrC–SiC composites were successfully fabricated by polymer infiltration and pyrolysis combined with ZrC precursor impregnation. The microstructure and mechanical properties of the composites were studied. The composite with PyC/SiC interphase had a bulk density of 2.14 g/cm{sup 3}, an open porosity of 10%, and a bending stress of 474 MPa, and exhibited a non-brittle failure behavior due to propagation and deflection of cracks, and fracture and pullout of fibers. Their high-temperature oxidation resistance and anti-ablation properties were evaluated using a muffle furnace and plasma wind tunnel test. Results show that the composites have good mechanical and excellent ablative properties.

  13. Degradation mechanism of alachlor during direct ozonation and O(3)/H(2)O(2) advanced oxidation process.

    Science.gov (United States)

    Qiang, Zhimin; Liu, Chao; Dong, Bingzhi; Zhang, Yalei

    2010-01-01

    The degradation of alachlor by direct ozonation and advanced oxidation process O(3)/H(2)O(2) was investigated in this study with focus on identification of degradation byproducts. The second-order reaction rate constant between ozone and alachlor was determined to be 2.5+/-0.1M(-1)s(-1) at pH 7.0 and 20 degrees C. Twelve and eight high-molecular-weight byproducts (with the benzene ring intact) from alachlor degradation were identified during direct ozonation and O(3)/H(2)O(2), respectively. The common degradation byproducts included N-(2,6-diethylphenyl)-methyleneamine, 8-ethyl-3,4-dihydro-quinoline, 8-ethyl-quinoline, 1-chloroacetyl-2-hydro-3-ketone-7-acetyl-indole, 2-chloro-2',6'-diacetyl-N-(methoxymethyl)acetanilide, 2-chloro-2'-acetyl-6'-ethyl-N-(methoxymethyl)-acetanilide, and two hydroxylated alachlor isomers. In direct ozonation, four more byproducts were also identified including 1-chloroacetyl-2,3-dihydro-7-ethyl-indole, 2-chloro-2',6'-ethyl-acetanilide, 2-chloro-2',6'-acetyl-acetanilide and 2-chloro-2'-ethyl-6'-acetyl-N-(methoxymethyl)-acetanilide. Degradation of alachlor by O(3) and O(3)/H(2)O(2) also led to the formation of low-molecular-weight byproducts including formic, acetic, propionic, monochloroacetic and oxalic acids as well as chloride ion (only detected in O(3)/H(2)O(2)). Nitrite and nitrate formation was negligible. Alachlor degradation occurred via oxidation of the arylethyl group, N-dealkylation, cyclization and cleavage of benzene ring. After O(3) or O(3)/H(2)O(2) treatment, the toxicity of alachlor solution examined by the Daphnia magna bioassay was slightly reduced. 2009 Elsevier Ltd. All rights reserved.

  14. Reliable and cost effective design of intermetallic Ni2Si nanowires and direct characterization of its mechanical properties

    OpenAIRE

    Seung Zeon Han; Joonhee Kang; Sung-Dae Kim; Si-Young Choi; Hyung Giun Kim; Jehyun Lee; Kwangho Kim; Sung Hwan Lim; Byungchan Han

    2015-01-01

    We report that a single crystal Ni2Si nanowire (NW) of intermetallic compound can be reliably designed using simple three-step processes: casting a ternary Cu-Ni-Si alloy, nucleate and growth of Ni2Si NWs as embedded in the alloy matrix via designing discontinuous precipitation (DP) of Ni2Si nanoparticles and thermal aging, and finally chemical etching to decouple the Ni2Si NWs from the alloy matrix. By direct application of uniaxial tensile tests to the Ni2Si NW we characterize its mechanica...

  15. Direct quantum mechanical calculation of the F + H{sub 2} {yields} HF + H thermal rate constant

    Energy Technology Data Exchange (ETDEWEB)

    Moix, Marc [Computer Simulation and Modeling (COSMO) Lab, Parc Cientific de Barcelona, Josep Samitier 5, 08028 Barcelona (Spain); Institut de Quimica Teorica i Computacional de la UB (IQTCUB), Universitat de Barcelona (Spain); Huarte-Larranaga, Fermin [Computer Simulation and Modeling (COSMO) Lab, Parc Cientific de Barcelona, Josep Samitier 5, 08028 Barcelona (Spain); Institut de Quimica Teorica i Computacional de la UB (IQTCUB), Universitat de Barcelona (Spain)], E-mail: fhuarte@pcb.ub.es

    2008-07-03

    Accurate full-dimensional quantum mechanical thermal rate constant values have been calculated for the F+H{sub 2}{yields}HF+H reaction on the Stark-Werner ab initio potential energy surface. These calculations are based on a flux correlation functions and employ a rigorous statistical sampling scheme to account for the overall rotation and the MCTDH scheme for the wave packet propagation. Our results shed some light on discrepancies on the thermal rate found for previous flux correlation based calculations with respect to accurate reactive scattering results. The resonance pattern of the all-J cumulative reaction probability is analyzed in terms of the partial wave contributions.

  16. Effects of almond consumption on the reduction of LDL-cholesterol: a discussion of potential mechanisms and future research directions.

    Science.gov (United States)

    Berryman, Claire E; Preston, Amy Griel; Karmally, Wahida; Deckelbaum, Richard J; Kris-Etherton, Penny M

    2011-04-01

    Diet plays a seminal role in the prevention and treatment of cardiovascular disease. Consumption of tree nuts has been shown to reduce low-density lipoprotein cholesterol (LDL-C), a primary target for coronary disease prevention, by 3-19%. Almonds have been found to have a consistent LDL-C-lowering effect in healthy individuals, and in individuals with high cholesterol and diabetes, in both controlled and free-living settings. Almonds are low in saturated fatty acids, rich in unsaturated fatty acids, and contain fiber, phytosterols, and plant protein. Other cardioprotective nutrients unique to almonds include α-tocopherol, arginine, magnesium, copper, manganese, calcium, and potassium. Mechanisms responsible for the LDL-C reduction observed with almond consumption are likely associated with the nutrients almonds provide. Biologically active by nature, these nutrients target primary mechanistic routes of LDL-C reduction, including decreased (re)absorption of cholesterol and bile acid, increased bile acid and cholesterol excretion, and increased LDL-C receptor activity. The nutrients present in almonds may regulate enzymes involved in de novo cholesterol synthesis and bile acid production. Research is needed to understand all mechanisms by which almonds reduce cardiovascular disease risk. © 2011 International Life Sciences Institute.

  17. Kinetics and mechanisms of thiol-disulfide exchange covering direct substitution and thiol oxidation-mediated pathways.

    Science.gov (United States)

    Nagy, Péter

    2013-05-01

    Disulfides are important building blocks in the secondary and tertiary structures of proteins, serving as inter- and intra-subunit cross links. Disulfides are also the major products of thiol oxidation, a process that has primary roles in defense mechanisms against oxidative stress and in redox regulation of cell signaling. Although disulfides are relatively stable, their reduction, isomerisation, and interconversion as well as their production reactions are catalyzed by delicate enzyme machineries, providing a dynamic system in biology. Redox homeostasis, a thermodynamic parameter that determines which reactions can occur in cellular compartments, is also balanced by the thiol-disulfide pool. However, it is the kinetic properties of the reactions that best represent cell dynamics, because the partitioning of the possible reactions depends on kinetic parameters. This review is focused on the kinetics and mechanisms of thiol-disulfide substitution and redox reactions. It summarizes the challenges and advances that are associated with kinetic investigations in small molecular and enzymatic systems from a rigorous chemical perspective using biological examples. The most important parameters that influence reaction rates are discussed in detail. Kinetic studies of proteins are more challenging than small molecules, and quite often investigators are forced to sacrifice the rigor of the experimental approach to obtain the important kinetic and mechanistic information. However, recent technological advances allow a more comprehensive analysis of enzymatic systems via using the systematic kinetics apparatus that was developed for small molecule reactions, which is expected to provide further insight into the cell's machinery.

  18. The Process of Nanostructuring of Metal (Iron Matrix in Composite Materials for Directional Control of the Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Elena Zemtsova

    2014-01-01

    Full Text Available We justified theoretical and experimental bases of synthesis of new class of highly nanostructured composite nanomaterials based on metal matrix with titanium carbide nanowires as dispersed phase. A new combined method for obtaining of metal iron-based composite materials comprising the powder metallurgy processes and the surface design of the dispersed phase is considered. The following stages of material synthesis are investigated: (1 preparation of porous metal matrix; (2 surface structuring of the porous metal matrix by TiC nanowires; (3 pressing and sintering to give solid metal composite nanostructured materials based on iron with TiC nanostructures with size 1–50 nm. This material can be represented as the material type “frame in the frame” that represents iron metal frame reinforcing the frame of different chemical compositions based on TiC. Study of material functional properties showed that the mechanical properties of composite materials based on iron with TiC dispersed phase despite the presence of residual porosity are comparable to the properties of the best grades of steel containing expensive dopants and obtained by molding. This will solve the problem of developing a new generation of nanostructured metal (iron-based materials with improved mechanical properties for the different areas of technology.

  19. Heat treatment of whole milk by the direct joule effect--experimental and numerical approaches to fouling mechanisms.

    Science.gov (United States)

    Fillaudeau, L; Winterton, P; Leuliet, J C; Tissier, J P; Maury, V; Semet, F; Debreyne, P; Berthou, M; Chopard, F

    2006-12-01

    The development of alternative technologies such as the direct Joule effect to pasteurize and sterilize food products is of great scientific and industrial interest. Our objective was 1) to gain insight into the ability to ensure ultra-high-temperature treatment of milk and 2) to investigate the links among thermal, hydraulic, and electrical phenomena in relation to fouling in a direct Joule effect heater. The ohmic heater [OH; E perpendicular to v (where E is the electrical field and v is the velocity); P (power) = 15 kW] was composed of 5 flat rectangular cells [e (space between the plate and electrode) = 15 mm, w (wall) = 76 mm, and L (length of the plate in plate heat exchanger or electrode) = 246 mm]--3 active cells to ensure heating and 2 (at the extremities) for electrical insulation and the recovery of leakage currents. In the first step, the thermal performance of the OH was investigated vs. the flow regimen [50 conductivity of fluids (0.1 thermal approach (thermal and electrical balance, modeling of the temperature profile of a fluid) and local analysis of the wall temperature of the electrode. An empirical correlation was established to estimate the temperature gradient, T(w)-T(b) (where T(w) is the wall temperature and T(b) is the product temperature) under clean conditions (without fouling) and was used to define operating conditions for pure-volume and direct-resistance heating. In the second step, the ability of OH to ensure the ultra-high-temperature treatment of whole milk was investigated and compared with a plate heat exchanger. Special care was taken to investigate the heat transfer phenomena occurring over a range of temperatures from 105 to 138 degrees C. This temperature range corresponds to the part of the process made critical by protein and mineral fouling. The objectives were 1) to demonstrate the ability of an OH to ensure heat treatment of milk, 2) to study the thermal and hydraulic performance with an increasing power and temperature

  20. Direct observation and mechanism for enhanced field emission sites in platinum ion implanted/post-annealed ultrananocrystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Kalpataru, E-mail: panda@afm.eei.eng.osaka-u.ac.jp, E-mail: phy.kalpa@gmail.com; Inami, Eiichi; Sugimoto, Yoshiaki [Graduate School of Engineering, Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871 (Japan); Sankaran, Kamatchi J.; Tai, Nyan Hwa [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Lin, I-Nan, E-mail: inanlin@mail.tku.edu.tw [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)

    2014-10-20

    Enhanced electron field emission (EFE) properties for ultrananocrystalline diamond (UNCD) films upon platinum (Pt) ion implantation and subsequent post-annealing processes is reported, viz., low turn-on field of 4.17 V/μm with high EFE current density of 5.08 mA/cm{sup 2} at an applied field of 7.0 V/μm. Current imaging tunneling spectroscopy (CITS) mode in scanning tunneling spectroscopy directly revealed the increased electron emission sites density for Pt ion implanted/post-annealed UNCD films than the pristine one. The high resolution CITS mapping and local current–voltage characteristic curves demonstrated that the electrons are dominantly emitted from the diamond grain boundaries and Pt nanoparticles.

  1. Direct observation and mechanism for enhanced field emission sites in platinum ion implanted/post-annealed ultrananocrystalline diamond films

    International Nuclear Information System (INIS)

    Panda, Kalpataru; Inami, Eiichi; Sugimoto, Yoshiaki; Sankaran, Kamatchi J.; Tai, Nyan Hwa; Lin, I-Nan

    2014-01-01

    Enhanced electron field emission (EFE) properties for ultrananocrystalline diamond (UNCD) films upon platinum (Pt) ion implantation and subsequent post-annealing processes is reported, viz., low turn-on field of 4.17 V/μm with high EFE current density of 5.08 mA/cm 2 at an applied field of 7.0 V/μm. Current imaging tunneling spectroscopy (CITS) mode in scanning tunneling spectroscopy directly revealed the increased electron emission sites density for Pt ion implanted/post-annealed UNCD films than the pristine one. The high resolution CITS mapping and local current–voltage characteristic curves demonstrated that the electrons are dominantly emitted from the diamond grain boundaries and Pt nanoparticles.

  2. Using verbal instructions to influence lifting mechanics - Does the directive "lift with your legs, not your back" attenuate spinal flexion?

    Science.gov (United States)

    Beach, Tyson A C; Stankovic, Tatjana; Carnegie, Danielle R; Micay, Rachel; Frost, David M

    2018-02-01

    "Use your legs" is commonly perceived as sound advice to prevent lifting-related low-back pain and injuries, but there is limited evidence that this directive attenuates the concomitant biomechanical risk factors. Body segment kinematic data were collected from 12 men and 12 women who performed a laboratory lifting/lowering task after being provided with different verbal instructions. The main finding was that instructing participants to lift "without rounding your lower back" had a greater effect on the amount of spine flexion they exhibited when lifting/lowering than instructing them to lift "with your legs instead of your back" and "bend your knees and hips". It was concluded that if using verbal instructions to discourage spine flexion when lifting, the instructions should be spine- rather than leg-focused. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Weaning mechanical ventilation after off-pump coronary artery bypass graft procedures directed by noninvasive gas measurements.

    Science.gov (United States)

    Chakravarthy, Murali; Narayan, Sandeep; Govindarajan, Raghav; Jawali, Vivek; Rajeev, Subramanyam

    2010-06-01

    Partial pressure of carbon dioxide and oxygen were transcutaneously measured in adults after off-pump coronary artery bypass (OPCAB) surgery. The clinical use of such measurements and interchangeability with arterial blood gas measurements for weaning patients from postoperative mechanical ventilation were assessed. This was a prospective observational study. Tertiary referral heart hospital. Postoperative OPCAB surgical patients. Transcutaneous oxygen and carbon dioxide measurements. In this prospective observational study, 32 consecutive adult patients in a tertiary care medical center underwent OPCAB surgery. Noninvasive measurement of respiratory gases was performed during the postoperative period and compared with arterial blood gases. The investigator was blinded to the reports of arterial blood gas studies and weaned patients using a "weaning protocol" based on transcutaneous gas measurement. The number of patients successfully weaned based on transcutaneous measurements and the number of times the weaning process was held up were noted. A total of 212 samples (pairs of arterial and transcutaneous values of oxygen and carbon dioxide) were obtained from 32 patients. Bland-Altman plots and mountain plots were used to analyze the interchangeability of the data. Twenty-five (79%) of the patients were weaned from the ventilator based on transcutaneous gas measurements alone. Transcutaneous carbon dioxide measurements were found to be interchangeable with arterial carbon dioxide during 96% of measurements, versus 79% for oxygen measurements. More than three fourths of the patients were weaned from mechanical ventilation and extubated based on transcutaneous gas values alone after OPCAB surgery. The noninvasive transcutaneous carbon dioxide measurement can be used as a surrogate for arterial carbon dioxide measurement to manage postoperative OPCAB patients. Copyright 2010 Elsevier Inc. All rights reserved.

  4. Cell Adhesion Minimization by a Novel Mesh Culture Method Mechanically Directs Trophoblast Differentiation and Self-Assembly Organization of Human Pluripotent Stem Cells.

    Science.gov (United States)

    Okeyo, Kennedy Omondi; Kurosawa, Osamu; Yamazaki, Satoshi; Oana, Hidehiro; Kotera, Hidetoshi; Nakauchi, Hiromitsu; Washizu, Masao

    2015-10-01

    Mechanical methods for inducing differentiation and directing lineage specification will be instrumental in the application of pluripotent stem cells. Here, we demonstrate that minimization of cell-substrate adhesion can initiate and direct the differentiation of human pluripotent stem cells (hiPSCs) into cyst-forming trophoblast lineage cells (TLCs) without stimulation with cytokines or small molecules. To precisely control cell-substrate adhesion area, we developed a novel culture method where cells are cultured on microstructured mesh sheets suspended in a culture medium such that cells on mesh are completely out of contact with the culture dish. We used microfabricated mesh sheets that consisted of open meshes (100∼200 μm in pitch) with narrow mesh strands (3-5 μm in width) to provide support for initial cell attachment and growth. We demonstrate that minimization of cell adhesion area achieved by this culture method can trigger a sequence of morphogenetic transformations that begin with individual hiPSCs attached on the mesh strands proliferating to form cell sheets by self-assembly organization and ultimately differentiating after 10-15 days of mesh culture to generate spherical cysts that secreted human chorionic gonadotropin (hCG) hormone and expressed caudal-related homeobox 2 factor (CDX2), a specific marker of trophoblast lineage. Thus, this study demonstrates a simple and direct mechanical approach to induce trophoblast differentiation and generate cysts for application in the study of early human embryogenesis and drug development and screening.

  5. Effect of Al substitution for Ga on the mechanical properties of directional solidified Fe-Ga alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yangyang; Li, Jiheng; Gao, Xuexu, E-mail: gaox@skl.ustb.edu.cn

    2017-02-01

    Alloys of Fe{sub 82}Ga{sub 18−x}Al{sub x} (x=0, 4.5, 6, 9, 12, 13.5) were prepared by directional solidification technique and exhibited a <001> preferred orientation along the axis of alloy rods. The saturation magnetostriction value of the Fe{sub 82}Ga{sub 13.5}Al{sub 4.5} alloy was 247 ppm under no pre-stress. The tensile properties of alloys of Fe{sub 82}Ga{sub 18−x}Al{sub x} at room temperature were investigated. The results showed that tensile ductility of binary Fe-Ga alloy was significantly improved with Al addition. The fracture elongation of the Fe{sub 82}Ga{sub 18} alloy was only 1.3%, while that of the Fe{sub 82}Ga{sub 9}Al{sub 9} alloy increased up to 16.5%. Addition of Al increased the strength of grain boundary and cleavage, resulting in the enhancement of tensile ductility of the Fe-Ga-Al alloys. Analysis of deformation microstructure showed that a great number of deformation twins formed in the Fe-Ga-Al alloys, which were thought to be the source of serrated yielding in the stress-strain curves. The effect of Al content in the Fe-Ga-Al alloys on tensile ductility was also studied by the analysis of deformation twins. It indicated that the joint effect of slip and twinning was beneficial to obtain the best ductility in the Fe{sub 82}Ga{sub 9}Al{sub 9} alloy. - Highlights: • Tensile ductility of directional solidified Fe-Ga alloys was significantly improved with Al addition. • The fracture elongation of binary Fe{sub 82}Ga{sub 18} alloy was only 1.3% at room temperature. • The fracture elongation of Fe{sub 82}Ga{sub 9}Al{sub 9} alloy was 16.5% at room temperature. • A great number of deformation twins formed in the Fe-Ga-Al alloys during tensile tests at room temperature.

  6. Triiodothyronine enhances accumulation of intracellular lipids in adipocytes through thyroid hormone receptor α via direct and indirect mechanisms.

    Science.gov (United States)

    Gambo, Yurina; Matsumura, Miki; Fujimori, Ko

    2016-08-15

    Triiodothyronine (T3) enhanced the expression of adipogenic and lipogenic genes with elevation of the intracellular lipids through thyroid hormone receptor (TR) α in mouse 3T3-L1 cells. However, the transcription of the SREBP-1c and HSL genes was decreased by T3. Such T3-mediated alterations were negated by TRα siRNA. Chromatin immunoprecipitation assay showed that the binding of TRα to the TR-responsive element (TRE) of the FAS promoter was elevated by T3. In contrast, the ability of TRα to bind to the TRE of the SREBP-1c promoter was decreased by T3. In addition, the binding of SREBP-1c to the SRE of the HSL promoter was lowered by T3. These results indicate that T3 increased the accumulation of intracellular lipids by enhancing the expression of the FAS gene through direct binding of TRα to the FAS promoter and simultaneously lowered the amount of lipolysis via reduced binding of T3-decreased SREBP-1c to the HSL promoter. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Chloroquine analogues in drug discovery: new directions of uses, mechanisms of actions and toxic manifestations from malaria to multifarious diseases.

    Science.gov (United States)

    Al-Bari, Md Abdul Alim

    2015-01-01

    Antimalarial drugs (e.g. chloroquine and its close structural analogues) were developed primarily to treat malaria; however, they are beneficial for many dermatological, immunological, rheumatological and severe infectious diseases, for which they are used mostly today. Chloroquine and hydroxychloroquine, two of the most fascinating drugs developed in the last 50 years, are increasingly recognized for their effectiveness in myriad non-malarial diseases. In advanced research, chloroquine and hydroxychloroquine have been shown to have various immunomodulatory and immunosuppressive effects, and currently have established roles in the management of rheumatic diseases, lupus erythematosus (different forms) and skin diseases, and in the treatment of different forms of cancer. Recently, chloroquine analogues have also been found to have metabolic, cardiovascular, antithrombotic and antineoplastic effects. This review is concerned with the lysosomotropic, anti-inflammatory and immunomodulatory mechanisms of chloroquine, hydroxychloroquine, quinacrine and related analogues, and the current evidence for both their beneficial effects and potential adverse manifestations in various diseases. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  8. TRADE LIBERALIZATION AND CONSUMER VULNERABILITY: A LEGAL FRAMEWORK ON LEGISLATIONS AND TESTING MECHANISM FOR ASEAN PRODUCT SAFETY DIRECTIVE

    Directory of Open Access Journals (Sweden)

    Syed Sagoff Alsagoff

    2017-01-01

    Full Text Available Since its inception in 1967 ASEAN has advanced in great leaps in the economic sector luring new member states into its pact. From a mere five member states (Malaysia, Indonesia, Thailand, Singapore and the Philippines ASEAN has today managed to entice five other neighbouring states (Brunei 1984, Vietnam 1995, Laos & Myanmar 1997, Cambodia 1999 into its pact transforming itself into union of ten member states with a consumer population expected to exceed 600 million people. In order to ensure sustainability amid global challenges, member states have engrossed ASEAN Charter in 2007 with a view of creating an ASEAN Economic Community by 2015 that is robust, competitive and sustainable. At this juncture, ASEAN has to realize that like any trade liberalization initiatives, goods moved readily and freely throughout the free-trade area that is facilitated by a lucrative non-barrier tariffs incentives. This vision of a single market which creates a frontier without borders can prove to be advantageous to member states only if they have the required vehicle that is able to overcome the drawback of its progression through harmonization and synchronization efforts that is effective and successful. Like everything else, every advantage has some disadvantages attached to it. This article will address important determining factors that are crucial in the development and scope of proposed ASEAN Product Safety Directive including reviewing relevant determining factors such as regional stability, consumer protection legislations and standard and testing agencies of which one without the other will be incomplete. The proposals suggested in this article will strengthen and unite ASEAN in overcoming unsafe product issues at ASEAN level.

  9. Transcranial direct current stimulation (tDCS) neuromodulatory effects on mechanical hyperalgesia and cortical BDNF levels in ovariectomized rats.

    Science.gov (United States)

    da Silva Moreira, Sônia Fátima; Medeiros, Liciane Fernandes; de Souza, Andressa; de Oliveira, Carla; Scarabelot, Vanessa Leal; Fregni, Felipe; Caumo, Wolnei; Torres, Iraci L S

    2016-01-15

    Epidemiological studies show that painful disorders are more prevalent in women than in men, and the transcranial direct current stimulation (tDCS) technique has been tested in chronic pain states. We explored the effect of tDCS on pain behavior and brain-derived neurotrophic factor (BDNF) levels in ovariectomized rats. Forty-five female Wistar adult rats were distributed into five groups: control (CT), ovariectomy + tDCS (OT), ovariectomy + sham tDCS (OS), sham ovariectomy + tDCS (ST), and sham ovariectomy+shamtDCS (SS). The rats were subjected to cathodal tDCS. The vaginal cytology and the estradiol levels confirmed the hormonal status. In addition, nociceptive behavior was evaluated using the tail-flick, von Frey, and hot-plate tests, as well as the BDNF levels in the serum, hypothalamus, hippocampus, spinal cord, and cerebral cortex. One-way analysis of variance (ANOVA) or two-way ANOVA was used for statistical analysis, followed by the Bonferroni, and P-value b 0.05 was considered significant. The ovariectomized animals presented a hypersensitivity response in the hot-plate (P b 0.01) and von Frey (P b 0.05) tests, as well as increased serum BDNF (P b 0.05) and decreased hypothalamic BDNF (P b 0.01) levels. The OT, OS, ST, and SS groups showed decreased hippocampal BDNF levels as compared with the control group (P b 0.001). The interaction between tDCS and ovariectomy on the cortical BDNF levels (P b 0.01) was observed. The ovariectomy induced nociceptive hypersensitivity and altered serum and hypothalamic BDNF levels. The cathodal tDCS partially reversed nociceptive hypersensitivity.

  10. Direct and indirect control of the initiation of meiotic recombination by DNA damage checkpoint mechanisms in budding yeast.

    Directory of Open Access Journals (Sweden)

    Bilge Argunhan

    Full Text Available Meiotic recombination plays an essential role in the proper segregation of chromosomes at meiosis I in many sexually reproducing organisms. Meiotic recombination is initiated by the scheduled formation of genome-wide DNA double-strand breaks (DSBs. The timing of DSB formation is strictly controlled because unscheduled DSB formation is detrimental to genome integrity. Here, we investigated the role of DNA damage checkpoint mechanisms in the control of meiotic DSB formation using budding yeast. By using recombination defective mutants in which meiotic DSBs are not repaired, the effect of DNA damage checkpoint mutations on DSB formation was evaluated. The Tel1 (ATM pathway mainly responds to unresected DSB ends, thus the sae2 mutant background in which DSB ends remain intact was employed. On the other hand, the Mec1 (ATR pathway is primarily used when DSB ends are resected, thus the rad51 dmc1 double mutant background was employed in which highly resected DSBs accumulate. In order to separate the effect caused by unscheduled cell cycle progression, which is often associated with DNA damage checkpoint defects, we also employed the ndt80 mutation which permanently arrests the meiotic cell cycle at prophase I. In the absence of Tel1, DSB formation was reduced in larger chromosomes (IV, VII, II and XI whereas no significant reduction was found in smaller chromosomes (III and VI. On the other hand, the absence of Rad17 (a critical component of the ATR pathway lead to an increase in DSB formation (chromosomes VII and II were tested. We propose that, within prophase I, the Tel1 pathway facilitates DSB formation, especially in bigger chromosomes, while the Mec1 pathway negatively regulates DSB formation. We also identified prophase I exit, which is under the control of the DNA damage checkpoint machinery, to be a critical event associated with down-regulating meiotic DSB formation.

  11. Towards an understanding of self-directed language as a mechanism of behavior change: A novel strategy for eliciting client language under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Benjamin O. Ladd

    2018-06-01

    Full Text Available Introduction: Change talk (CT and sustain talk (ST are thought to reflect underlying motivation and be important mechanisms of behavior change (MOBCs. However, greater specificity and experimental rigor is needed to establish CT and ST as MOBCs. Testing the effects of self-directed language under laboratory conditions is one promising avenue. The current study presents a replication and extension of research examining the feasibility for using simulation tasks to elicit self-directed language. Methods: First-year college students (N=92 responded to the Collegiate Simulated Intoxication Digital Elicitation, a validated task for assessing decision-making in college drinking. Verbal responses elicited via free-response and structured interview formats were coded based on established definitions of CT and ST, with minor modifications to reflect the non-treatment context. Associations between self-directed language and alcohol use at baseline and eight months were examined. Additionally, this study examined whether a contextually-based measure of decision-making, behavioral willingness, mediated relationships between self-directed language and alcohol outcome. Results: Healthy talk and unhealthy talk independently were associated with baseline alcohol use across both elicitation formats. Only healthy talk during the free-response elicitation was associated with alcohol use at follow up; both healthy talk and unhealthy talk during the interview elicitation were associated with 8-month alcohol use. Behavioral willingness significantly mediated the relationship between percent healthy talk and alcohol outcome. Conclusions: Findings support the utility of studying self-directed language under laboratory conditions and suggest that such methods may provide a fruitful strategy to further understand the role of self-directed language as a MOBC. Keywords: Change talk, College students, Alcohol, Simulation task

  12. Systems Biology Reveals Cigarette Smoke-Induced Concentration-Dependent Direct and Indirect Mechanisms That Promote Monocyte-Endothelial Cell Adhesion.

    Science.gov (United States)

    Poussin, Carine; Laurent, Alexandra; Peitsch, Manuel C; Hoeng, Julia; De Leon, Hector

    2015-10-01

    Cigarette smoke (CS) affects the adhesion of monocytes to endothelial cells, a critical step in atherogenesis. Using an in vitro adhesion assay together with innovative computational systems biology approaches to analyze omics data, our study aimed at investigating CS-induced mechanisms by which monocyte-endothelial cell adhesion is promoted. Primary human coronary artery endothelial cells (HCAECs) were treated for 4 h with (1) conditioned media of human monocytic Mono Mac-6 (MM6) cells preincubated with low or high concentrations of aqueous CS extract (sbPBS) from reference cigarette 3R4F for 2 h (indirect treatment, I), (2) unconditioned media similarly prepared without MM6 cells (direct treatment, D), or (3) freshly generated sbPBS (fresh direct treatment, FD). sbPBS promoted MM6 cells-HCAECs adhesion following I and FD, but not D. In I, the effect was mediated at a low concentration through activation of vascular inflammation processes promoted in HCAECs by a paracrine effect of the soluble mediators secreted by sbPBS-treated MM6 cells. Tumor necrosis factor α (TNFα), a major inducer, was actually shed by unstable CS compound-activated TNFα-converting enzyme. In FD, the effect was triggered at a high concentration that also induced some toxicity. This effect was mediated through an yet unknown mechanism associated with a stress damage response promoted in HCAECs by unstable CS compounds present in freshly generated sbPBS, which had decayed in D unconditioned media. Aqueous CS extract directly and indirectly promotes monocytic cell-endothelial cell adhesion in vitro via distinct concentration-dependent mechanisms. © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  13. The Breakdown Mechanisms In Electrical Discharges: The Role Of The Field Emission Effect In Direct Current Discharges In Micro gaps

    International Nuclear Information System (INIS)

    Radmilovic-Radjenovic, M.; Radjenovic, B.; Bojarov, A.; Klas, M.; Matejcik, S.

    2013-01-01

    This review represents an attempt to sum up the current state of the research in the field of breakdown phenomena in electrical discharges. The paper provides facts and theories concerning different classes of direct current, radio and microwave frequency discharges, in vacuum, in the gas and in liquids, without and in the presence of the magnetic fields. The emphasize was made on the field emission effects and on the fundamental aspects of the breakdown phenomena in micro discharges via discussions and analysis of the experimental, theoretical and simulation results. It was found that the Paschen's law is not applicable for the micron gap sizes, when deviations from the standard scaling law become evident and modified Paschen curve should be used. The explanation of the deviations from the Paschen law was attributed to the secondary electron emission enhanced by the strong field generated in micro gaps. The experiments were carried out in order to establish scaling law in micro gaps. The volt-ampere characteristics were also recorded and compared with the theoretical predictions based on the Fowler-Nordheim theory. The importance of the enhancement factor and the space charge on results was also considered. On the basis of the experimental breakdown voltage curves, the effective yields in micro gaps have been estimated for different gases which can be served as input data in modeling. The effective yields allow analytically produce modified Paschen curves that predicts the deviations from the Paschen law observed in the experiments. In addition, we present results of computer simulations using a Particle-in-cell/Monte Carlo Collisions (PIC/MCC) code with the secondary emission model in order to include the field emission enhanced secondary electron production in micro gaps. The agreement between simulation and experimental results suggest that computer simulations can be used to improve understanding of the plasma physics as an alternative to analytical

  14. What is the scope for the Dutch government to use the flexible mechanisms of the Renewables Directive cost-effectively? A preliminary assessment

    International Nuclear Information System (INIS)

    Jansen, J.C.; Uslu, A.; Lako, P.

    2010-03-01

    This report provides a preliminary assessment of the scope for cost-effective use by the Dutch government of each of four flexible mechanisms available to EU Member States to achieve their respective mandatory renewables target in year 2020. The flexible mechanisms, defined in the Renewables Directive 2009/28/CE, are: Statistical transfers between Member States; Joint projects between Member States; Joint projects between Member States and third countries; Joint support schemes. In theory, statistical transfers and joint support schemes are the flexible mechanisms with the most potential for cost-effective use. The Dutch government is advised to explore each of these options. In this report, it is argued that in practice well-designed joint support schemes are likely to turn out having most potential. To that effect, the report presents a concrete suggestion on the most promising short-term application. To successfully harness a substantial part of the joint support schemes potential warrants protracted efforts in the design phase: the devil is in the detail. Moreover, the joint projects between Member States mechanism may well turn out to provide some interesting opportunities. For collaboration between the Netherlands and a selection of (four) other Member States some technologies to focus upon are identified. Reasons are given why the flexible instrument joint projects between Member States and third countries is poised to have quite limited potential to cost-effectively contribute to the Dutch renewables target in year 2020.

  15. Populisme et démocratie semi-directe : la dénaturation des procédés référendaires en France et aux Etats-Unis

    Directory of Open Access Journals (Sweden)

    Christophe Premat

    2005-09-01

    Full Text Available Si le populisme se caractérise par l’incarnation d’un ensemble de frustrations à l’égard du système représentatif, il est primordial de s’interroger sur le lien entre une déception à l’égard des institutions et les instruments de démocratie semi-directe. En nous appuyant sur une comparaison entre la France et les Etats-Unis pour analyser d´une part comment le référendum et l’initiative populaire ont modifié la donne dans certains Etats américains et d’autre part comment en France les référendums nationaux ont connu la suspicion « plébiscitaire » à plusieurs reprises, nous souhaiterions comprendre si par nature la démocratie semi-directe n’est que le ressentiment engendré par la lenteur du travail de représentation ou si elle est le complément essentiel à la transformation du régime représentatif.Si la frustración contra el sistema representativo es expresada por el populismo, es crucial interrogarse por el acoplamiento entre una decepción relacionada con las instituciones y los instrumentos semidirectos de la democracia. Al comparar Francia con Estados Unidos con el objetivo de analizar por una parte, cómo las iniciativas populares y los referendums influenciaron la legislación de algunos estados americanos y por otra, cómo los referéndums nacionales en Francia fueron reducidos a plebiscitos, intentamos descifrar si la naturaleza de la democracia semidirecta es el resultado de un resentimiento contra la lentitud del trabajo representativo o si concluye la transformación del gobierno representativo.If the feelings of frustration against the representative system are expressed by populism, it is crucial to question the link between a disappointment vis-à-vis the institutions and the semi-direct democracy instruments. By comparing France and United States in order to analyze on the one hand how popular initiatives and referenda influenced the legislation of some American States and on the other

  16. A mechanical property and stress corrosion evaluation of VIM-ESR-VAR work strengthened and direct double aged Inconel 718 bar material

    Science.gov (United States)

    Montano, J. W.

    1986-01-01

    Presented are the mechanical properties and the stress corrosion resistance of triple melted vacuum induction melted (VIM), electro-slag remelted (ESR), and vacuum arc remelted (VAR), solution treated, work strengthened and direct double aged Inconel 718 alloy bars 4.00 in. (10.16) and 5.75 in. (14.60 cm) diameter. Tensile, charpy v-notched impact, and compact tension specimens were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 220 ksi (1516.85 MPa) and 200 ksi (1378.00 MPa) respectively, were realized at ambient temperature. Additional charpy impact and compact tension tests were performed at -100 F (-73 C). Longitudinal charpy impact strength equalled or exceeded 12.0 ft-lbs (16.3 Joules) at ambient and at -100 F(-73 C) while longitudinal compact (LC) tension fracture toughness strength remained above 79 ksi (86.80 MPa) at ambient and at -100 F(-73 C) temperatures. No failures occurred in the longitudinal or transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test indicated no mechanical property degradation.

  17. Effectiveness of hands-on tutoring and guided self-directed learning versus self-directed learning alone to educate critical care fellows on mechanical ventilation - a pilot project.

    Science.gov (United States)

    Ramar, Kannan; De Moraes, Alice Gallo; Selim, Bernardo; Holets, Steven; Oeckler, Richard

    2016-01-01

    Physicians require extensive training to achieve proficiency in mechanical ventilator (MV) management of the critically ill patients. Guided self-directed learning (GSDL) is usually the method used to learn. However, it is unclear if this is the most proficient approach to teaching mechanical ventilation to critical care fellows. We, therefore, investigated whether critical care fellows achieve higher scores on standardized testing and report higher satisfaction after participating in a hands-on tutorial combined with GSDL compared to self-directed learning alone. First-year Pulmonary and Critical Care Medicine (PCCM) fellows ( n =6) and Critical Care Internal Medicine (CCIM) ( n =8) fellows participated. Satisfaction was assessed using the Likert scale. MV knowledge assessment was performed by administering a standardized 25-question multiple choice pre- and posttest. For 2 weeks the CCIM fellows were exposed to GSDL, while the PCCM fellows received hands-on tutoring combined with GSDL. Ninety-three percentage (6 PCCM and 7 CCIM fellows, total of 13 fellows) completed all evaluations and were included in the final analysis. CCIM and PCCM fellows scored similarly in the pretest (64% vs. 52%, p =0.13). Following interventions, the posttest scores increased in both groups. However, no significant difference was observed based on the interventions (74% vs. 77%, p =0.39). The absolute improvement with the hands-on-tutoring and GSDL group was higher than GSDL alone (25% vs. 10%, p =0.07). Improved satisfaction scores were noted with hands-on tutoring. Hands-on tutoring combined with GSDL and GSDL alone were both associated with an improvement in posttest scores. Absolute improvement in test and satisfaction scores both trended higher in the hands-on tutorial group combined with GSDL group.

  18. Effectiveness of hands-on tutoring and guided self-directed learning versus self-directed learning alone to educate critical care fellows on mechanical ventilation – a pilot project

    Directory of Open Access Journals (Sweden)

    Kannan Ramar

    2016-09-01

    Full Text Available Background: Physicians require extensive training to achieve proficiency in mechanical ventilator (MV management of the critically ill patients. Guided self-directed learning (GSDL is usually the method used to learn. However, it is unclear if this is the most proficient approach to teaching mechanical ventilation to critical care fellows. We, therefore, investigated whether critical care fellows achieve higher scores on standardized testing and report higher satisfaction after participating in a hands-on tutorial combined with GSDL compared to self-directed learning alone. Methods: First-year Pulmonary and Critical Care Medicine (PCCM fellows (n=6 and Critical Care Internal Medicine (CCIM (n=8 fellows participated. Satisfaction was assessed using the Likert scale. MV knowledge assessment was performed by administering a standardized 25-question multiple choice pre- and posttest. For 2 weeks the CCIM fellows were exposed to GSDL, while the PCCM fellows received hands-on tutoring combined with GSDL. Results: Ninety-three percentage (6 PCCM and 7 CCIM fellows, total of 13 fellows completed all evaluations and were included in the final analysis. CCIM and PCCM fellows scored similarly in the pretest (64% vs. 52%, p=0.13. Following interventions, the posttest scores increased in both groups. However, no significant difference was observed based on the interventions (74% vs. 77%, p=0.39. The absolute improvement with the hands-on-tutoring and GSDL group was higher than GSDL alone (25% vs. 10%, p=0.07. Improved satisfaction scores were noted with hands-on tutoring. Conclusions: Hands-on tutoring combined with GSDL and GSDL alone were both associated with an improvement in posttest scores. Absolute improvement in test and satisfaction scores both trended higher in the hands-on tutorial group combined with GSDL group.

  19. Direct observation of solid-phase adsorbate concentration profile in powdered activated carbon particle to elucidate mechanism of high adsorption capacity on super-powdered activated carbon.

    Science.gov (United States)

    Ando, Naoya; Matsui, Yoshihiko; Matsushita, Taku; Ohno, Koichi

    2011-01-01

    Decreasing the particle size of powdered activated carbon (PAC) by pulverization increases its adsorption capacities for natural organic matter (NOM) and polystyrene sulfonate (PSS, which is used as a model adsorbate). A shell adsorption mechanism in which NOM and PSS molecules do not completely penetrate the adsorbent particle and instead preferentially adsorb near the outer surface of the particle has been proposed as an explanation for this adsorption capacity increase. In this report, we present direct evidence to support the shell adsorption mechanism. PAC particles containing adsorbed PSS were sectioned with a focused ion beam, and the solid-phase PSS concentration profiles of the particle cross-sections were directly observed by means of field emission-scanning electron microscopy/energy-dispersive X-ray spectrometry (FE-SEM/EDXS). X-ray emission from sulfur, an index of PSS concentration, was higher in the shell region than in the inner region of the particles. The X-ray emission profile observed by EDXS did not agree completely with the solid-phase PSS concentration profile predicted by shell adsorption model analysis of the PSS isotherm data, but the observed and predicted profiles were not inconsistent when the analytical errors were considered. These EDXS results provide the first direct evidence that PSS is adsorbed mainly in the vicinity of the external surface of the PAC particles, and thus the results support the proposition that the increase in NOM and PSS adsorption capacity with decreasing particle size is due to the increase in external surface area on which the molecules can be adsorbed. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Direct detection of male quality can facilitate the evolution of female choosiness and indicators of good genes: Evolution across a continuum of indicator mechanisms.

    Science.gov (United States)

    Dhole, Sumit; Stern, Caitlin A; Servedio, Maria R

    2018-04-01

    The evolution of mating displays as indicators of male quality has been the subject of extensive theoretical and empirical research for over four decades. Research has also addressed the evolution of female mate choice favoring such indicators. Yet, much debate still exists about whether displays can evolve through the indirect benefits of female mate choice. Here, we use a population genetic model to investigate how the extent to which females can directly detect male quality influences the evolution of female choosiness and male displays. We use a continuum framework that incorporates indicator mechanisms that are traditionally modeled separately. Counter to intuition, we find that intermediate levels of direct detection of male quality can facilitate, rather than impede, the evolution of female choosiness and male displays in broad regions of this continuum. We examine how this evolution is driven by selective forces on genetic quality and on the display, and find that direct detection of male quality results in stronger indirect selection favoring female choosiness. Our results imply that displays maybe more likely to evolve when female choosiness has already evolved to discriminate perceptible forms of male quality. They also highlight the importance of considering general female choosiness, as well as preference, in studies of "good genes." © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

  1. Wetting-layer formation mechanisms of surface-directed phase separation under different quench depths with off-critical compositions in polymer binary mixture

    Science.gov (United States)

    Yan, Li-Tang; Xie, Xu-Ming

    2007-02-01

    Focusing on the off-critical condition, the quench depth dependence of surface-directed phase separation in the polymer binary mixture is numerically investigated by combination of the Cahn-Hilliard-Cook theory and the Flory-Huggins-de Gennes theory. Two distinct situations, i.e., for the wetting, the minority component is preferred by the surface and the majority component is preferred by the surface, are discussed in detail. The simulated results show that the formation mechanism of the wetting layer is affected by both the quench depth and the off-critical extent. Moreover, a diagram, illustrating the formation mechanisms of the wetting layer with various quench depths and compositions, is obtained on the basis of the simulated results. It is found that, when the minority component is preferred by the surface, the growth of the wetting layer can exhibit pure diffusion limited growth law, logarithmic growth law, and Lifshitz-Slyozov growth law. However, when the majority component is preferred by the surface, the wetting layer always grows logarithmically, regardless of the quench depth and the off-critical extent. It is interesting that the surface-induced nucleation can be observed in this case. The simulated results demonstrate that the surface-induced nucleation only occurs below a certain value of the quench depth, and a detailed range about it is calculated and indicated. Furthermore, the formation mechanisms of the wetting layer are theoretically analyzed in depth by the chemical potential gradient.

  2. The competition of charge remote and charge directed fragmentation mechanisms in quaternary ammonium salt derivatized peptides--an isotopic exchange study.

    Science.gov (United States)

    Cydzik, Marzena; Rudowska, Magdalena; Stefanowicz, Piotr; Szewczuk, Zbigniew

    2011-12-01

    Derivatization of peptides as quaternary ammonium salts (QAS) is a promising method for sensitive detection by electrospray ionization tandem mass spectrometry (Cydzik et al. J. Pept. Sci. 2011, 17, 445-453). The peptides derivatized by QAS at their N-termini undergo fragmentation according to the two competing mechanisms - charge remote (ChR) and charge directed (ChD). The absence of mobile proton in the quaternary salt ion results in ChR dissociation of a peptide bond. However, Hofmann elimination of quaternary salt creates an ion with one mobile proton leading to the ChD fragmentation. The experiments on the quaternary ammonium salts with deuterated N-alkyl groups or amide NH bonds revealed that QAS derivatized peptides dissociate according to the mixed ChR-ChD mechanism. The isotopic labeling allows differentiation of fragments formed according to ChR and ChD mechanisms. © The Author(s) 2011. This article is published with open access at Springerlink.com

  3. A macro-directive mechanism that facilitates automatic updating and processing of the contents of Electronic Healthcare Records: an extension to the CEN architecture.

    Science.gov (United States)

    Deftereos, S; Lambrinoudakis, C; Gritzalis, S; Georgonikou, D; Andriopoulos, P; Aessopos, A

    2003-03-01

    Facilitating data entry, eliminating redundant effort and providing decision support are some of the factors upon which the successful uptake of Electronic Healthcare Record (EHCR) technology is dependent. The European Standardization Committee (CEN), on the other hand, has proposed a standard EHCR architecture, which allows patient record contents to be highly diverse, customized to individual user needs; this makes their processing a challenging task and poses a demand for specially designed mechanisms. We describe the requirements for a macro-directive mechanism, pertaining to CEN-compatible EHCR software that can automate updating and processing of patient records, thus enhancing the functionality of the software. We have implemented the above-mentioned mechanism in an EHCR application that has been customized for use in the care process of patients suffering from beta-Thalassemia. The application is being used during the last two years in the Thalassemia units of four Greek hospitals, as part of their every day practice. We report on the experience we have acquired so far.

  4. Direct Metal Laser Sintering of Ti6Al4V for Biomedical Applications: Microstructure, Corrosion Properties, and Mechanical Treatment of Implants

    Directory of Open Access Journals (Sweden)

    Janette Brezinová

    2016-07-01

    Full Text Available Ti6Al4V samples have been prepared by Direct Metal Laser Sintering (DMLS with varied laser power. Some of the samples were stress-relief annealed. The microstructure of materials was investigated using a light microscopy. Columnar grains of martensite dominate in as-made microstructure. Stress-relief annealing led to the white acicular phase growth in the structure with a fishbone arrangement on the boundary of some original martensitic needles. Mechanical properties of materials were characterized through hardness measurement in two directions relating to the sample building direction. It was found that the hardness of materials increased with a laser power and values varied from 370 to 415 HV 0.3/30. After stress-relief annealing, the structure of materials being homogenized, pattern spacing dissolved and the hardness in both directions became stabilized at values of 350–370 HV 0.3/30. The laser power affects the corrosion rate of the material. The lowest corrosion rate was recorded at the maximum laser power (190 W. Heat treatment does not affect the corrosion rate remarkably, however it leads to stabilization of corrosion potential of materials Ecorr. The surface of the samples was modified by an abrasive blasting using spherical (zirblast and sharp-edged (white corundum blasting abrasives and three levels of air pressure. The abrasive blasting of sintered materials led to a decrease of the surface roughness of materials with air pressure increasing. Blasting with zirblast led to a more significant decrease of roughness parameters compared with surfaces blasted with sharp-edged white aluminum. Different shapes of abrasives caused characteristic surface morphology.

  5. Site-directed mutagenesis of the Arabidopsis heterotrimeric G protein β subunit suggests divergent mechanisms of effector activation between plant and animal G proteins.

    Science.gov (United States)

    Chakravorty, David; Trusov, Yuri; Botella, José Ramón

    2012-03-01

    Heterotrimeric G proteins are integral components of signal transduction in humans and other mammals and have been therefore extensively studied. However, while they are known to mediate many processes, much less is currently known about the effector pathways and molecular mechanisms used by these proteins to regulate effectors in plants. We designed a complementation strategy to study G protein signaling in Arabidopsis thaliana, particularly the mechanism of action of AGB1, the sole identified β subunit. We used biochemical and effector regulation data from human G protein studies to identify four potentially important residues for site-directed mutagenesis (T65, M111, D250 and W361 of AGB1). Each residue was individually mutated and the resulting mutated protein introduced in the agb1-2 mutant background under the control of the native AGB1 promoter. Interestingly, even though these mutations have been shown to have profound effects on effector signaling in humans, all the mutated subunits were able to restore thirteen of the fifteen Gβ-deficient phenotypes characterized in this study. Only one mutated protein, T65A was unable to complement the hypersensitivity to mannitol during germination observed in agb1 mutants; while only D250A failed to restore lateral root numbers in the agb1 mutant to wild-type levels. Our results suggest that the mechanisms used in mammalian G protein signaling are not well conserved in plant G protein signaling, and that either the effectors used by plant G proteins, or the mechanisms used to activate them, are at least partially divergent from the well-studied mammalian G proteins.

  6. Direct reduction of N-acetoxy-PhIP by tea polyphenols: a possible mechanism for chemoprevention against PhIP-DNA adduct formation

    International Nuclear Information System (INIS)

    Lin Dongxin; Thompson, Patricia A.; Teitel, Candee; Chen Junshi; Kadlubar, Fred F.

    2003-01-01

    The chemopreventive effect of tea against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-DNA adduct formation and its mechanism were studied. Rats were exposed to freshly prepared aqueous extracts of green tea (3% (w/v)) as the sole source of drinking water for 10 days prior to administration with a single dose of PhIP (10 mg/kg body weight) by oral gavage. PhIP-DNA adducts in the liver, colon, heart, and lung were measured using the 32 P-postlabelling technique. Rats pre-treated with tea and given PhIP 20 h before sacrifice had significantly reduced levels of PhIP-DNA adducts as compared with controls given PhIP alone. The possible mechanism of protective effect of tea on PhIP-DNA adduct formation was then examined in vitro. It was found that an aqueous extract of green and black tea, mixtures of green and black tea polyphenols, as well as purified polyphenols could strongly inhibit the DNA binding of N-acetoxy-PhIP, a putative ultimate carcinogen of PhIP formed in vivo via metabolic activation. Among these, epigallocatechin gallate was exceptionally potent. HPLC analyses of these incubation mixtures containing N-acetoxy-PhIP and the tea polyphenols each revealed the production of the parent amine, PhIP, indicating the involvement of a redox mechanism. In view of the presence of relatively high levels of tea polyphenols in rat and human plasma after ingestion of tea, this study suggests that direct reduction of the ultimate carcinogen N-acetoxy-PhIP by tea polyphenols is likely to be involved in the mechanism of chemoprotection of tea against this carcinogen

  7. Directed polymers versus directed percolation

    Science.gov (United States)

    Halpin-Healy, Timothy

    1998-10-01

    Universality plays a central role within the rubric of modern statistical mechanics, wherein an insightful continuum formulation rises above irrelevant microscopic details, capturing essential scaling behaviors. Nevertheless, occasions do arise where the lattice or another discrete aspect can constitute a formidable legacy. Directed polymers in random media, along with its close sibling, directed percolation, provide an intriguing case in point. Indeed, the deep blood relation between these two models may have sabotaged past efforts to fully characterize the Kardar-Parisi-Zhang universality class, to which the directed polymer belongs.

  8. Insights into the deactivation mechanism of supported tungsten hydride on alumina (W-H/Al2O3) catalyst for the direct conversion of ethylene to propylene

    KAUST Repository

    Mazoyer, Etienne

    2014-04-01

    Tungsten hydride supported on alumina prepared by the surface organometallic chemistry method is an active precursor for the direct conversion of ethylene to propylene at low temperature and pressure. An extensive contact time study revealed that the dimerization of ethylene to 1-butene is the primary and also the rate limiting step. The catalytic cycle further involves isomerization of 1-butene to 2-butene, followed by cross-metathesis of ethylene and 2-butene to yield propylene with high selectivity. The deactivation mechanism of this reaction has been investigated. The used catalyst was extensively examined by DRIFTS, solid-state NMR, EPR, UV-Vis, TGA and DSC techniques. It was found that a large amount of carbonaceous species, which were due to side reaction like olefin polymerization took place with time on stream, significantly hindering the dimerization of ethylene to 1-butene and therefore the production of propylene. Crown Copyright © 2014 Published by Elsevier B.V. All rights reserved.

  9. Different (direct and indirect) mechanisms for the induction of DNA-protein crosslinks in human cells by far- and near-ultraviolet radiations (290 and 405 nm)

    International Nuclear Information System (INIS)

    Peak, M.J.; Peak, J.G.; Jones, C.A.

    1985-01-01

    Apparent DNA-protein crosslinking induced by monochromatic 290 and 405 nm radiations was measured in cultured human P3 teratocarcinoma cells with DNA alkaline elution techniques. The rates of the induction of crosslinks by 290 nm radiation were the same when the cells were irradiated either aerobically or anaerobically or when the cells were in an H 2 O or D 2 O aqueous environment. With 405 nm radiation, anaerobic irradiation reduced the induction of the crosslinks (dose modifying factor is about 0.2), and about twice as many crosslinks were observed when the cells were irradiated in an environment of D 2 O rather than H 2 O. The results are consistent with the hypothesis that far-UV radiation induces DNA-protein crosslinks by a direct mechanism, whereas near-UV radiation induces crosslinks via indirect photodynamic photosensitizations in which unidentified cellular endogenous photosensitizers and reactive species of oxygen are used. (author)

  10. Direct and indirect mechanisms for the induction of apparent DNA-protein crosslinks by far- and near-ultraviolet radiations in human cells in culture

    International Nuclear Information System (INIS)

    Peak, M.J.; Peak, J.G.; Jones, C.A.

    1985-01-01

    DNA from human epithelioid P/sub 3/ cells in culture was studied by alkaline elution techniques after the cells were irradiated by monochromatic 254, 290, 313, 334, 365, 405, 434, and 545 nm ultraviolet light. An action spectrum (aerobic irradiation) for the relative efficiency of induction of apparent DNA-protein covalent bonds (crosslinks) showed a maximum at about 254 nm, with a secondary peak of activity at 405 nm. No changes in the crosslink production by 290 nm radiation were observed when the cells were irradiated under anoxic conditions or in an environment of D/sub 2/O. Under anoxic conditions, the induction of crosslinks was reduced by 80% at 405 nm, and, in the presence of D/sub 2/O, it was doubled. These findings constitute evidence that far- and near-UV radiations induce crosslinks by direct (absorption of photons directly by DNA) and indirect (photosensitizations involving nonDNA cellular sensitizers and reactive species of oxygen) mechanisms respectively

  11. Comparative study of the microstructures and mechanical properties of direct laser fabricated and arc-melted Al{sub x}CoCrFeNi high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Jithin, E-mail: jithin@deakin.edu.au [Institute for Frontier Materials, Deakin University, Waurn Ponds 3216 (Australia); Jarvis, Tom; Wu, Xinhua [Monash Centre for Additive Manufacturing, Monash University, Clayton 3168 (Australia); Stanford, Nicole; Hodgson, Peter; Fabijanic, Daniel Mark [Institute for Frontier Materials, Deakin University, Waurn Ponds 3216 (Australia)

    2015-05-01

    High entropy alloys (HEA) are a relatively new metal alloy system that have promising potential in high temperature applications. These multi-component alloys are typically produced by arc-melting, requiring several remelts to achieve chemical homogeneity. Direct laser fabrication (DLF) is a rapid prototyping technique, which produces complex components from alloy powder by selectively melting micron-sized powder in successive layers. However, studies of the fabrication of complex alloys from simple elemental powder blends are sparse. In this study, DLF was employed to fabricate bulk samples of three alloys based on the Al{sub x}CoCrFeNi HEA system, where x was 0.3, 0.6 and 0.85 M fraction of Al. This produced FCC, FCC/BCC and BCC crystal structures, respectively. Corresponding alloys were also produced by arc-melting, and all microstructures were characterised and compared longitudinal and transverse to the build/solidification direction by x-ray diffraction, glow discharge optical emission spectroscopy and scanning electron microscopy (EDX and EBSD). Strong similarities were observed between the single phase FCC and BCC alloys produced by both techniques, however the FCC/BCC structures differed significantly. This has been attributed to a difference in the solidification rate and thermal gradient in the melt pool between the two different techniques. Room temperature compression testing showed very similar mechanical behaviour and properties for the two different processing routes. DLF was concluded to be a successful technique to manufacture bulk HEA's.

  12. A Ring Polymer Molecular Dynamics Approach to Study the Transition between Statistical and Direct Mechanisms in the H2 + H3+ → H3+ + H2 Reaction.

    Science.gov (United States)

    Suleimanov, Yury V; Aguado, Alfredo; Gómez-Carrasco, Susana; Roncero, Octavio

    2018-05-03

    Because of its fundamental importance in astrochemistry, the H 2 + H 3 + → H 3 + + H 2 reaction has been studied experimentally in a wide temperature range. Theoretical studies of the title reaction significantly lag primarily because of the challenges associated with the proper treatment of the zero-point energy (ZPE). As a result, all previous theoretical estimates for the ratio between a direct proton-hop and indirect exchange (via the H 5 + complex) channels deviate from the experiment, in particular, at lower temperatures where the quantum effects dominate. In this work, the ring polymer molecular dynamics (RPMD) method is applied to study this reaction, providing very good agreement with the experiment. RPMD is immune to the shortcomings associated with the ZPE leakage and is able to describe the transition from direct to indirect mechanisms below room temperature. We argue that RPMD represents a useful tool for further studies of numerous ZPE-sensitive chemical reactions that are of high interest in astrochemistry.

  13. Synthesis of kaolin supported nanoscale zero-valent iron and its degradation mechanism of Direct Fast Black G in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Xiaoying; Chen, Zhengxian [Fujian Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province (China); Zhou, Rongbing [Institute of Environ Sci and Engineering, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018 (China); Chen, Zuliang, E-mail: Zuliang.chen@unisa.edu.au [Fujian Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province (China); Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2015-01-15

    Graphical abstract: UV–visible spectra of DFBG solution using K-nZVI (1:1) nanoparticles. (a) Before reaction; (b) during reaction; (c) after reaction. - Highlights: • Kaolin-supported Fe{sup 0} nanoparticle (K-nZVI) was synthesized. • Degradation of Direct Fast Black by K-nZVI was studied. • K-nZVI was characterized by SEM, XRD, UV and FIIR. • Degradation mechanism of Direct Fast Black was proposed. - Abstract: Calcinated kaolin supported nanoscale zero-valent iron (K-nZVI) was synthesized and used for the removal of tetrad azo-group dye-Direct Fast Black G (DFBG) from aqueous solution. The results demonstrated that after reacting for 10 min with an initial concentration of DFBG 100 mg L{sup −1} (pH 9.49), 78.60% of DFBG was removed using K-nZVI, while only 41.39% and 12.56% of DFBG were removed using nZVI and kaolin, respectively. K-nZVI with a mass ratio of nZVI nanoparticles versus kaolin at 1:1 was found to have a high degree of reactivity. Furthermore, scanning electron microscopy (SEM) confirmed that nZVI was better dispersed when kaolin was present. XRD patterns indicated that iron oxides were formed after reaction. Fourier transforms infrared spectra (FTIR) and UV–visible demonstrated that the peak in the visible light region of DFBG was degraded and new bands were observed. Kinetics studies showed that the degradation of DFBG fitted well to the pseudo first-order model. The degradation of DFBG by K-nZVI was based on its adsorption onto kaolin and iron oxides, and subsequently reduction using nZVI was proposed. A significant outcome emerged in that 99.84% of DFBG in wastewater was removed using K-nZVI after reacting for 60 min.

  14. Direct binding of microRNA-21 pre-element with Regorafenib: An alternative mechanism for anti-colorectal cancer chemotherapy?

    Science.gov (United States)

    Chen, Xiaobing; Xie, Bojian; Cao, Liang; Zhu, Feng; Chen, Beibei; Lv, Huifang; Fan, Xingxing; Han, Lili; Bie, Liangyu; Cao, Xinguang; Shen, Xiaokun; Cao, Feilin

    2017-05-01

    The Regorafenib is a broad-spectrum kinase inhibitor that has been approved to treat colorectal cancer (CRC). However, evidences have shown that the agent is also implicated in drug interaction with microRNA-21 (miR-21), an oncogenic miRNA which plays a key role in resisting programmed cell death in CRC cells. Here, we supposed that, instead of kinase inhibition, Regorafenib can directly bind to and then stabilize miR-21 pre-element, thus preventing RNase Dicer-meditated cleavage of the pre-element to mature miR-21. In order to verify the notion, an in silico-in vitro integrated investigation of the direct intermolecular interaction between Regorafenib and miR-21 pre-element was performed by using active pocket identification, RNA-ligand docking, molecular dynamics (MD) simulation, binding energetic analysis, and fluorescence-based assay. It was revealed that the Regorafenib can bind at the major groove-like stem region of miR-21 pre-element through three geometrically satisfactory hydrogen bonds (H-bonds) as well as a number of hydrophobic forces and π-π stacking, conferring strong specificity and high stability to the RNA-ligand complex system (K d =0.73μM). Separate inversion mutation of two base pairs (G6C, C12G) and (A13U, U4A) that are involved in the H-bonding can considerably impair the affinity of Regorafenib to miR-21 pre-element, with K d increase to 27 and 96μM, respectively. All these supported that Regorafenib can directly bind to miR-21 pre-element at molecular level and the binding mode can be properly modeled by using the proposed integrated strategy. This study would provide a potential, alternative mechanism for anti-colorectal cancer chemotherapy with Regorafenib. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Synthesis of kaolin supported nanoscale zero-valent iron and its degradation mechanism of Direct Fast Black G in aqueous solution

    International Nuclear Information System (INIS)

    Jin, Xiaoying; Chen, Zhengxian; Zhou, Rongbing; Chen, Zuliang

    2015-01-01

    Graphical abstract: UV–visible spectra of DFBG solution using K-nZVI (1:1) nanoparticles. (a) Before reaction; (b) during reaction; (c) after reaction. - Highlights: • Kaolin-supported Fe 0 nanoparticle (K-nZVI) was synthesized. • Degradation of Direct Fast Black by K-nZVI was studied. • K-nZVI was characterized by SEM, XRD, UV and FIIR. • Degradation mechanism of Direct Fast Black was proposed. - Abstract: Calcinated kaolin supported nanoscale zero-valent iron (K-nZVI) was synthesized and used for the removal of tetrad azo-group dye-Direct Fast Black G (DFBG) from aqueous solution. The results demonstrated that after reacting for 10 min with an initial concentration of DFBG 100 mg L −1 (pH 9.49), 78.60% of DFBG was removed using K-nZVI, while only 41.39% and 12.56% of DFBG were removed using nZVI and kaolin, respectively. K-nZVI with a mass ratio of nZVI nanoparticles versus kaolin at 1:1 was found to have a high degree of reactivity. Furthermore, scanning electron microscopy (SEM) confirmed that nZVI was better dispersed when kaolin was present. XRD patterns indicated that iron oxides were formed after reaction. Fourier transforms infrared spectra (FTIR) and UV–visible demonstrated that the peak in the visible light region of DFBG was degraded and new bands were observed. Kinetics studies showed that the degradation of DFBG fitted well to the pseudo first-order model. The degradation of DFBG by K-nZVI was based on its adsorption onto kaolin and iron oxides, and subsequently reduction using nZVI was proposed. A significant outcome emerged in that 99.84% of DFBG in wastewater was removed using K-nZVI after reacting for 60 min

  16. Effect of intercritical deformation on microstructure and mechanical properties of a low-silicon aluminum-added hot-rolled directly quenched and partitioned steel

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Xiao-Dong, E-mail: tan.x@mpie.de [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Xu, Yun-Bo, E-mail: yunbo_xu@126.com [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Ponge, Dirk [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Yang, Xiao-Long; Hu, Zhi-Ping; Peng, Fei [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Ju, Xiao-Wei [CERI LONG PRODUCT CO., LTD., Beijing 100176 (China); Wu, Di [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Raabe, Dierk [Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf (Germany)

    2016-02-22

    Here, we applied hot-rolling in conjunction with direct quenching and partitioning (HDQ&P) processes with different rolling schedules to a low-C low-Si Al-added steel. Ferrite was introduced into the steel by intercritical rolling and air cooling after hot-rolling. The effect of intercritcal deformation on the microstructure evolution and mechanical properties was investigated. The promotion of austenite stabilization and the optimization of the TRIP effect due to a moderate degree of intercritical deformation were systematically explored. The results show that the addition of 1.46 wt% of Al can effectively promote ferrite formation. An intercritical deformation above 800 °C can result in a pronounced bimodal grain size distribution of ferrite and some elongated ferrite grains containing sub-grains. The residual strain states of both austenite and ferrite and the occurrence of bainite transformation jointly increase the retained austenite fraction due to its mechanical stabilization and the enhanced carbon partitioning into austenite from its surrounding phases. An intercritical deformation below 800 °C can profoundly increase the ferrite fraction and promote the recrystallization of deformed ferrite. The formation of this large fraction of ferrite enhances the carbon enrichment in the untransformed austenite and retards the bainite transformation during the partitioning process and finally enhances martensite transformation and decreases the retained austenite fraction. The efficient TRIP effect of retained austenite and the possible strain partitioning of bainite jointly improve the work hardening and formability of the steel and lead to the excellent mechanical properties with relatively high tensile strength (905 MPa), low yield ratio (0.60) and high total elongation (25.2%).

  17. Axisymmetric alternating direction explicit scheme for efficient coupled simulation of hydro-mechanical interaction in geotechnical engineering—Application to circular footing and deep tunnel in saturated ground

    Directory of Open Access Journals (Sweden)

    Simon Heru Prassetyo

    2018-04-01

    Full Text Available Explicit solution techniques have been widely used in geotechnical engineering for simulating the coupled hydro-mechanical (H-M interaction of fluid flow and deformation induced by structures built above and under saturated ground, i.e. circular footing and deep tunnel. However, the technique is only conditionally stable and requires small time steps, portending its inefficiency for simulating large-scale H-M problems. To improve its efficiency, the unconditionally stable alternating direction explicit (ADE scheme could be used to solve the flow problem. The standard ADE scheme, however, is only moderately accurate and is restricted to uniform grids and plane strain flow conditions. This paper aims to remove these drawbacks by developing a novel high-order ADE scheme capable of solving flow problems in non-uniform grids and under axisymmetric conditions. The new scheme is derived by performing a fourth-order finite difference (FD approximation to the spatial derivatives of the axisymmetric fluid–diffusion equation in a non-uniform grid configuration. The implicit Crank-Nicolson technique is then applied to the resulting approximation, and the subsequent equation is split into two alternating direction sweeps, giving rise to a new axisymmetric ADE scheme. The pore pressure solutions from the new scheme are then sequentially coupled with an existing geomechanical simulator in the computer code fast Lagrangian analysis of continua (FLAC. This coupling procedure is called the sequentially-explicit coupling technique based on the fourth-order axisymmetric ADE scheme or SEA-4-AXI. Application of SEA-4-AXI for solving axisymmetric consolidation of a circular footing and of advancing tunnel in deep saturated ground shows that SEA-4-AXI reduces computer runtime up to 42%–50% that of FLAC's basic scheme without numerical instability. In addition, it produces high numerical accuracy of the H-M solutions with average percentage difference of only 0.5%

  18. Different Molecular Mechanisms Mediate Direct or Glia-Dependent Prion Protein Fragment 90-231 Neurotoxic Effects in Cerebellar Granule Neurons.

    Science.gov (United States)

    Thellung, Stefano; Gatta, Elena; Pellistri, Francesca; Villa, Valentina; Corsaro, Alessandro; Nizzari, Mario; Robello, Mauro; Florio, Tullio

    2017-10-01

    Glia over-stimulation associates with amyloid deposition contributing to the progression of central nervous system neurodegenerative disorders. Here we analyze the molecular mechanisms mediating microglia-dependent neurotoxicity induced by prion protein (PrP)90-231, an amyloidogenic polypeptide corresponding to the protease-resistant portion of the pathological prion protein scrapie (PrP Sc ). PrP90-231 neurotoxicity is enhanced by the presence of microglia within neuronal culture, and associated to a rapid neuronal [Ca ++ ] i increase. Indeed, while in "pure" cerebellar granule neuron cultures, PrP90-231 causes a delayed intracellular Ca ++ entry mediated by the activation of NMDA receptors; when neuron and glia are co-cultured, a transient increase of [Ca ++ ] i occurs within seconds after treatment in both granule neurons and glial cells, then followed by a delayed and sustained [Ca ++ ] i raise, associated with the induction of the expression of inducible nitric oxide synthase and phagocytic NADPH oxidase. [Ca ++ ] i fast increase in neurons is dependent on the activation of multiple pathways since it is not only inhibited by the blockade of voltage-gated channel activity and NMDA receptors but also prevented by the inhibition of nitric oxide and PGE 2 release from glial cells. Thus, Ca ++ homeostasis alteration, directly induced by PrP90-231 in cerebellar granule cells, requires the activation of NMDA receptors, but is greatly enhanced by soluble molecules released by activated glia. In glia-enriched cerebellar granule cultures, the activation of inducible nitric oxide (iNOS) and NADPH oxidase represents the main mechanism of toxicity since their pharmacological inhibition prevented PrP90-231 neurotoxicity, whereas NMDA blockade by D(-)-2-amino-5-phosphonopentanoic acid is ineffective; conversely, in pure cerebellar granule cultures, NMDA blockade but not iNOS inhibition strongly reduced PrP90-231 neurotoxicity. These data indicate that amyloidogenic peptides

  19. Investigation of the direct runoff generation mechanism for the analysis of the SCS-CN method applicability to a partial area experimental watershed

    Science.gov (United States)

    Soulis, K. X.; Valiantzas, J. D.; Dercas, N.; Londra, P. A.

    2009-05-01

    The Soil Conservation Service Curve Number (SCS-CN) method is widely used for predicting direct runoff volume for a given rainfall event. The applicability of the SCS-CN method and the direct runoff generation mechanism were thoroughly analysed in a Mediterranean experimental watershed in Greece. The region is characterized by a Mediterranean semi-arid climate. A detailed land cover and soil survey using remote sensing and GIS techniques, showed that the watershed is dominated by coarse soils with high hydraulic conductivities, whereas a smaller part is covered with medium textured soils and impervious surfaces. The analysis indicated that the SCS-CN method fails to predict runoff for the storm events studied, and that there is a strong correlation between the CN values obtained from measured runoff and the rainfall depth. The hypothesis that this correlation could be attributed to the existence of an impermeable part in a very permeable watershed was examined in depth, by developing a numerical simulation water flow model for predicting surface runoff generated from each of the three soil types of the watershed. Numerical runs were performed using the HYDRUS-1D code. The results support the validity of this hypothesis for most of the events examined where the linear runoff formula provides better results than the SCS-CN method. The runoff coefficient of this formula can be taken equal to the percentage of the impervious area. However, the linear formula should be applied with caution in case of extreme events with very high rainfall intensities. In this case, the medium textured soils may significantly contribute to the total runoff and the linear formula may significantly underestimate the runoff produced.

  20. Investigation of the direct runoff generation mechanism for the analysis of the SCS-CN method applicability to a partial area experimental watershed

    Directory of Open Access Journals (Sweden)

    K. X. Soulis

    2009-05-01

    Full Text Available The Soil Conservation Service Curve Number (SCS-CN method is widely used for predicting direct runoff volume for a given rainfall event. The applicability of the SCS-CN method and the direct runoff generation mechanism were thoroughly analysed in a Mediterranean experimental watershed in Greece. The region is characterized by a Mediterranean semi-arid climate. A detailed land cover and soil survey using remote sensing and GIS techniques, showed that the watershed is dominated by coarse soils with high hydraulic conductivities, whereas a smaller part is covered with medium textured soils and impervious surfaces. The analysis indicated that the SCS-CN method fails to predict runoff for the storm events studied, and that there is a strong correlation between the CN values obtained from measured runoff and the rainfall depth. The hypothesis that this correlation could be attributed to the existence of an impermeable part in a very permeable watershed was examined in depth, by developing a numerical simulation water flow model for predicting surface runoff generated from each of the three soil types of the watershed. Numerical runs were performed using the HYDRUS-1D code. The results support the validity of this hypothesis for most of the events examined where the linear runoff formula provides better results than the SCS-CN method. The runoff coefficient of this formula can be taken equal to the percentage of the impervious area. However, the linear formula should be applied with caution in case of extreme events with very high rainfall intensities. In this case, the medium textured soils may significantly contribute to the total runoff and the linear formula may significantly underestimate the runoff produced.

  1. Chemical proteomics approach reveals the direct targets and the heme-dependent activation mechanism of artemisinin in Plasmodium falciparum using an activity-based artemisinin probe

    Directory of Open Access Journals (Sweden)

    Jigang Wang

    2016-04-01

    Full Text Available Artemisinin and its analogues are currently the most effective anti-malarial drugs. The activation of artemisinin requires the cleavage of the endoperoxide bridge in the presence of iron sources. Once activated, artemisinins attack macromolecules through alkylation and propagate a series of damages, leading to parasite death. Even though several parasite proteins have been reported as artemisinin targets, the exact mechanism of action (MOA of artemisinin is still controversial and its high potency and specificity against the malaria parasite could not be fully accounted for. Recently, we have developed an unbiased chemical proteomics approach to directly probe the MOA of artemisinin in P. falciparum. We synthesized an activity-based artemisinin probe with an alkyne tag, which can be coupled with biotin through click chemistry. This enabled selective purification and identification of 124 protein targets of artemisinin. Many of these targets are critical for the parasite survival. In vitro assays confirmed the specific artemisinin binding and inhibition of selected targets. We thus postulated that artemisinin kills the parasite through disrupting its biochemical landscape. In addition, we showed that artemisinin activation requires heme, rather than free ferrous iron, by monitoring the extent of protein binding using a fluorescent dye coupled with the alkyne-tagged artemisinin. The extremely high level of heme released from the hemoglobin digestion by the parasite makes artemisinin exceptionally potent against late-stage parasites (trophozoite and schizont stages compared to parasites at early ring stage, which have low level of heme, possibly derived from endogenous synthesis. Such a unique activation mechanism also confers artemisinin with extremely high specificity against the parasites, while the healthy red blood cells are unaffected. Our results provide a sound explanation of the MOA of artemisinin and its specificity against malaria

  2. Crystallinity, etchability, electrical and mechanical properties of Ga doped amorphous indium tin oxide thin films deposited by direct current magnetron sputtering

    International Nuclear Information System (INIS)

    Lee, Hyun-Jun; Song, Pung-Keun

    2014-01-01

    Indium tin oxide (ITO) and Ga-doped ITO (ITO:Ga) films were deposited on glass and polyimide (PI) substrates by direct current (DC) magnetron sputtering using different ITO:Ga targets (doped-Ga: 0, 0.1 and 2.9 wt.%). The films were deposited with a thickness of 50 nm and then post-annealed at various temperatures (room temperature-250 °C) in a vacuum chamber for 30 min. The amorphous ITO:Ga (0.1 wt.% Ga) films post-annealed at 220 °C exhibited relatively low resistivity (4.622x10 −4 Ω cm), indicating that the crystallinity of the ITO:Ga films decreased with increasing Ga content. In addition, the amorphous ITO:Ga films showed a better surface morphology, etchability and mechanical properties than the ITO films. - Highlights: • The Ga doped indium tin oxide (ITO) films crystallized at higher temperatures than the ITO films. • The amorphisation of ITO films increases with increasing Ga content. • Similar resistivity was observed between crystalline ITO and amorphous Ga doped ITO films. • Etching property of ITO film was improved with increasing Ga content

  3. Mechanism and comparison of needle-type non-thermal direct and indirect atmospheric pressure plasma jets on the degradation of dyes

    Science.gov (United States)

    Attri, Pankaj; Yusupov, Maksudbek; Park, Ji Hoon; Lingamdinne, Lakshmi Prasanna; Koduru, Janardhan Reddy; Shiratani, Masaharu; Choi, Eun Ha; Bogaerts, Annemie

    2016-10-01

    Purified water supply for human use, agriculture and industry is the major global priority nowadays. The advanced oxidation process based on atmospheric pressure non-thermal plasma (NTP) has been used for purification of wastewater, although the underlying mechanisms of degradation of organic pollutants are still unknown. In this study we employ two needle-type atmospheric pressure non-thermal plasma jets, i.e., indirect (ID-APPJ) and direct (D-APPJ) jets operating at Ar feed gas, for the treatment of methylene blue, methyl orange and congo red dyes, for two different times (i.e., 20 min and 30 min). Specifically, we study the decolorization/degradation of all three dyes using the above mentioned plasma sources, by means of UV-Vis spectroscopy, HPLC and a density meter. We also employ mass spectroscopy to verify whether only decolorization or also degradation takes place after treatment of the dyes by the NTP jets. Additionally, we analyze the interaction of OH radicals with all three dyes using reactive molecular dynamics simulations, based on the density functional-tight binding method. This investigation represents the first report on the degradation of these three different dyes by two types of NTP setups, analyzed by various methods, and based on both experimental and computational studies.

  4. Deconstructing therapeutic mechanisms in cancer support groups: do we express more emotion when we tell stories or talk directly to each other?

    Science.gov (United States)

    Tamagawa, Rie; Li, Yong; Gravity, Theo; Piemme, Karen Altree; DiMiceli, Sue; Collie, Kate; Giese-Davis, Janine

    2015-02-01

    Studies indicate that story-telling and emotional expression may be important therapeutic mechanisms. This study examined how they work together over 1 year of supportive-expressive group therapy (SET). Participants were 41 women randomized to SET. We coded emotional expression and story types (story vs. non-story) at the initial session, 4, 8, and 12 months. Women engaged in more storytelling in their initial than later sessions. In later sessions, women expressed significantly more emotion, specifically compassion and high-arousal positive affect. Direct communication (non-story) allowed more positive but also more defensive expression as women supported and challenged each other. Greater hostility in non-story and greater constrained anger during story were associated with increasing depression. Greater high-arousal positive affect in non-story and greater primary negative affect in story were associated with increasing social network size. These results inform clinicians about cues they might use to improve the effectiveness of cancer support groups.

  5. Discovery of potent 1H-imidazo[4,5-b]pyridine-based c-Met kinase inhibitors via mechanism-directed structural optimization.

    Science.gov (United States)

    An, Xiao-De; Liu, Hongyan; Xu, Zhong-Liang; Jin, Yi; Peng, Xia; Yao, Ying-Ming; Geng, Meiyu; Long, Ya-Qiu

    2015-02-01

    Starting from our previously identified novel c-Met kinase inhibitors bearing 1H-imidazo[4,5-h][1,6]naphthyridin-2(3H)-one scaffold, a global structural exploration was conducted to furnish an optimal binding motif for further development, directed by the enzyme inhibitory mechanism. First round SAR study picked two imidazonaphthyridinone frameworks with 1,8- and 3,5-disubstitution pattern as class I and class II c-Met kinase inhibitors, respectively. Further structural optimization on type II inhibitors by truncation of the imidazonaphthyridinone core and incorporation of an N-phenyl cyclopropane-1,1-dicarboxamide pharmacophore led to the discovery of novel imidazopyridine-based c-Met kinase inhibitors, displaying nanomolar enzyme inhibitory activity and improved Met kinase selectivity. More significantly, the new chemotype c-Met kinase inhibitors effectively inhibited Met phosphorylation and its downstream signaling as well as the proliferation of Met-dependent EBC-1 human lung cancer cells at submicromolar concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Numerical simulation of physicochemical interactions between oxygen atom and phosphatidylcholine due to direct irradiation of atmospheric pressure nonequilibrium plasma to biological membrane with quantum mechanical molecular dynamics

    Science.gov (United States)

    Uchida, Satoshi; Yoshida, Taketo; Tochikubo, Fumiyoshi

    2017-10-01

    Plasma medicine is one of the most attractive applications using atmospheric pressure nonequilibrium plasma. With respect to direct contact of the discharge plasma with a biological membrane, reactive oxygen species play an important role in induction of medical effects. However, complicated interactions between the plasma radicals and membrane have not been understood well. In the present work, we simulated elemental processes at the first stage of physicochemical interactions between oxygen atom and phosphatidylcholine using the quantum mechanical molecular dynamics code in a general software AMBER. The change in the above processes was classified according to the incident energy of oxygen atom. At an energy of 1 eV, the abstraction of a hydrogen atom and recombination to phosphatidylcholine were simultaneously occurred in chemical attachment of incident oxygen atom. The exothermal energy of the reaction was about 80% of estimated one based on the bond energies of ethane. An oxygen atom over 10 eV separated phosphatidylcholine partially. The behaviour became increasingly similar to physical sputtering. The reaction probability of oxygen atom was remarkably high in comparison with that of hydrogen peroxide. These results suggest that we can uniformly estimate various physicochemical dynamics of reactive oxygen species against membrane lipids.

  7. To Study Capping or Lamination Tendency of Tablets Through Evaluation of Powder Rheological Properties and Tablet Mechanical Properties of Directly Compressible Blends.

    Science.gov (United States)

    Dudhat, Siddhi M; Kettler, Charles N; Dave, Rutesh H

    2017-05-01

    Air entrapment efficiency of the powders is one of the main factors leading to occurrence of capping or lamination tendency of tablets manufactured from the directly compressible powder blends. The purpose of the current research was to study this underlying cause leading to occurrence of capping or lamination of tablets through evaluation of powder rheological properties. Powder blends were prepared by addition of 0% w/w to 100% w/w of individual active pharmaceutical ingredient (API) [two model API: acetaminophen (APAP) and ibuprofen (IBU)] with microcrystalline cellulose without and with 0.5% w/w Magnesium Stearate as lubricant. Powder rheological properties were analyzed using FT4 Powder Rheometer for dynamic, bulk, and shear properties. Tablet mechanical properties of the respective blends were studied by determining the ability of the material to form tablet of specific strength under applied compaction pressure through tabletability profile. The results showed that powder rheometer distinguished the powder blends based on their ability to relieve entrapped air along with the distinctive flow characteristics. Powder blend prepared with increasing addition of APAP displayed low powder permeability as compared to IBU blends with better powder permeability, compressibility and flow characteristics. Also, lubrication of the APAP blends did not ease their ability to relieve air. Tabletability profiles revealed the potential occurrence of capping or lamination in tablets prepared from the powder blends with high APAP content. This study can help scientist to understand tableting performance at the early-developmental stages and can avoid occurrence capping and lamination of tablets.

  8. Mechanical behavior of bulk direct composite versus block composite and lithium disilicate indirect Class II restorations by CAD-FEM modeling.

    Science.gov (United States)

    Ausiello, Pietro; Ciaramella, Stefano; Fabianelli, Andrea; Gloria, Antonio; Martorelli, Massimo; Lanzotti, Antonio; Watts, David C

    2017-06-01

    To study the influence of resin based and lithium disilicate materials on the stress and strain distributions in adhesive class II mesio-occlusal-distal (MOD) restorations using numerical finite element analysis (FEA). To investigate the materials combinations in the restored teeth during mastication and their ability to relieve stresses. One 3D model of a sound lower molar and three 3D class II MOD cavity models with 95° cavity-margin-angle shapes were modelled. Different material combinations were simulated: model A, with a 10μm thick resin bonding layer and a resin composite bulk filling material; model B, with a 70μm resin cement with an indirect CAD-CAM resin composite inlay; model C, with a 70μm thick resin cement with an indirect lithium disilicate machinable inlay. To simulate polymerization shrinkage effects in the adhesive layers and bulk fill composite, the thermal expansion approach was used. Shell elements were employed for representing the adhesive layers. 3D solid CTETRA elements with four grid points were employed for modelling the food bolus and tooth. Slide-type contact elements were used between the tooth surface and food. A vertical occlusal load of 600 N was applied, and nodal displacements on the bottom cutting surfaces were constrained in all directions. All the materials were assumed to be isotropic and elastic and a static linear analysis was performed. Displacements were different in models A, B and C. Polymerization shrinkage hardly affected model A and mastication only partially affected mechanical behavior. Shrinkage stress peaks were mainly located marginally along the enamel-restoration interface at occlusal and mesio-distal sites. However, at the internal dentinal walls, stress distributions were critical with the highest maximum stresses concentrated in the proximal boxes. In models B and C, shrinkage stress was only produced by the 70μm thick resin layer, but the magnitudes depended on the Young's modulus (E) of the inlay

  9. Mechanisms of strand break formation in DNA due to the direct effect of ionizing radiation: the dependency of free base release on the length of alternating CG oligodeoxynucleotides.

    Science.gov (United States)

    Sharma, Kiran K; Razskazovskiy, Yuriy; Purkayastha, Shubhadeep; Bernhard, William A

    2009-06-11

    The question of how NA base sequence influences the yield of DNA strand breaks produced by the direct effect of ionizing radiation was investigated in a series of oligodeoxynucleotides of the form (d(CG)(n))(2) and (d(GC)(n))(2). The yields of free base release from X-irradiated DNA films containing 2.5 waters/nucleotide were measured by HPLC as a function of oligomer length. For (d(CG)(n))(2), the ratio of the Gua yield to Cyt yield, R, was relatively constant at 2.4-2.5 for n = 2-4 and it decreased to 1.2 as n increased from 5 to 10. When Gua was moved to the 5' end, for example going from d(CG)(5) to d(GC)(5), R dropped from 1.9 +/- 0.1 to 1.1 +/- 0.1. These effects are poorly described if the chemistry at the oligomer ends is assumed to be independent of the remainder of the oligomer. A mathematical model incorporating charge transfer through the base stack was derived to explain these effects. In addition, EPR was used to measure the yield of trapped-deoxyribose radicals at 4 K following X-irradiation at 4 K. The yield of free base release was substantially greater, by 50-100 nmol/J, than the yield of trapped-deoxyribose radicals. Therefore, a large fraction of free base release stems from a nonradical intermediate. For this intermediate, a deoxyribose carbocation formed by two one-electron oxidations is proposed. This reaction pathway requires that the hole (electron loss site) transfers through the base stack and, upon encountering a deoxyribose hole, oxidizes that site to form a deoxyribose carbocation. This reaction mechanism provides a consistent way of explaining both the absence of trapped radical intermediates and the unusual dependence of free base release on oligomer length.

  10. A direct thrombin inhibitor suppresses protein C activation and factor Va degradation in human plasma: Possible mechanisms of paradoxical enhancement of thrombin generation.

    Science.gov (United States)

    Kamisato, Chikako; Furugohri, Taketoshi; Morishima, Yoshiyuki

    2016-05-01

    We have demonstrated that antithrombin (AT)-independent thrombin inhibitors paradoxically increase thrombin generation (TG) in human plasma in a thrombomodulin (TM)- and protein C (PC)-dependent manner. We determined the effects of AT-independent thrombin inhibitors on the negative-feedback system, activation of PC and production and degradation of factor Va (FVa), as possible mechanisms underlying the paradoxical enhancement of TG. TG in human plasma containing 10nM TM was assayed by means of the calibrated automated thrombography. As an index of PC activation, plasma concentration of activated PC-PC inhibitor complex (aPC-PCI) was measured. The amounts of FVa heavy chain and its degradation product (FVa(307-506)) were examined by western blotting. AT-independent thrombin inhibitors, melagatran and dabigatran (both at 25-600nM) and 3-30μg/ml active site-blocked thrombin (IIai), increased peak levels of TG. Melagatran, dabigatran and IIai significantly decreased plasma concentration of aPC-PCI complex at 25nM or more, 75nM or more, and 10 and 30μg/ml, respectively. Melagatran (300nM) significantly increased FVa and decreased FVa(307-506). In contrast, a direct factor Xa inhibitor edoxaban preferentially inhibited thrombin generation (≥25nM), and higher concentrations were required to inhibit PC activation (≥150nM) and FVa degradation (300nM). The present study suggests that the inhibitions of protein C activation and subsequent degradation of FVa and increase in FVa by antithrombin-independent thrombin inhibitors may contribute to the paradoxical TG enhancement, and edoxaban may inhibit PC activation and FVa degradation as a result of TG suppression. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Hydrogen Permeation, and Mechanical and Tribological Behavior, of CrNx Coatings Deposited at Various Bias Voltages on IN718 by Direct Current Reactive Sputtering

    Directory of Open Access Journals (Sweden)

    Egor B. Kashkarov

    2018-02-01

    Full Text Available In the current work, the microstructure, hydrogen permeability, and properties of chromium nitride (CrNx thin films deposited on the Inconel 718 superalloy using direct current reactive sputtering are investigated. The influence of the substrate bias voltage on the crystal structure, mechanical, and tribological properties before and after hydrogen exposure was studied. It was found that increasing the substrate bias voltage leads to densification of the coating. X-ray diffraction (XRD results reveal a change from mixed fcc-CrN + hcp-Cr2N to the approximately stoichiometric hcp-Cr2N phase with increasing substrate bias confirmed by wavelength-dispersive X-ray spectroscopy (WDS. The texture coefficients of (113, (110, and (111 planes vary significantly with increasing substrate bias voltage. The hydrogen permeability was measured by gas-phase hydrogenation. The CrN coating deposited at 60 V with mixed c-CrN and (113 textured hcp-Cr2N phases exhibits the lowest hydrogen absorption at 873 K. It is suggested that the crystal orientation is only one parameter influencing the permeation resistance of the CrNx coating together with the film structure, the presence of mixing phases, and the packing density of the structure. After hydrogenation, the hardness increased for all coatings, which could be related to the formation of a Cr2O3 oxide film on the surface, as well as the defect formation after hydrogen loading. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient by up to 40%. The lowest value of 0.25 ± 0.02 was reached for the CrNx coating deposited at 60 V after hydrogenation.

  12. GSK-3 directly regulates phospho-4EBP1 in renal cell carcinoma cell-line: an intrinsic subcellular mechanism for resistance to mTORC1 inhibition

    International Nuclear Information System (INIS)

    Ito, Hiromi; Ichiyanagi, Osamu; Naito, Sei; Bilim, Vladimir N.; Tomita, Yoshihiko; Kato, Tomoyuki; Nagaoka, Akira; Tsuchiya, Norihiko

    2016-01-01

    additivity at lower concentrations, but antagonism at higher concentrations. GSK-3β could directly phosphorylate 4EBP1 and activate the mTORC1 downstream signaling cascades to enhance protein biosynthesis and cell proliferation in RCC cell lines independent of rapamycin sensitivity. The direct GSK-3β/4EBP1 pathway might be an important subcellular mechanism as an inherent equipment for RCC cells to acquire clinical chemoresistance to mTORC1 inhibitors. The online version of this article (doi:10.1186/s12885-016-2418-7) contains supplementary material, which is available to authorized users

  13. Evolution of direct mechanisms with incident energy from the Coulomb-barrier to relativistic energies. - Two-center effects in nucleon transfer between nuclei. - Signatures of nucleon promotion in heavy ion reactions at barrier energies

    International Nuclear Information System (INIS)

    Oertzen, W. von; Voit, H.; Imanishi, B.

    1988-10-01

    This report contains a review article considering the evolution of direct mechanisms with incident energy in heavy ion reactions and two theoretical articles concerning two-center effects in transfer reactions between heavy ions and the nucleon promotion in heavy ion reactions. See hints under the relevant topics. (HSI)

  14. Novel model of direct and indirect cost-benefit analysis of mechanical embolectomy over IV tPA for large vessel occlusions: a real-world dollar analysis based on improvements in mRS.

    Science.gov (United States)

    Mangla, Sundeep; O'Connell, Keara; Kumari, Divya; Shahrzad, Maryam

    2016-01-20

    Ischemic strokes result in significant healthcare expenditures (direct costs) and loss of quality-adjusted life years (QALYs) (indirect costs). Interventional therapy has demonstrated improved functional outcomes in patients with large vessel occlusions (LVOs), which are likely to reduce the economic burden of strokes. To develop a novel real-world dollar model to assess the direct and indirect cost-benefit of mechanical embolectomy compared with medical treatment with intravenous tissue plasminogen activator (IV tPA) based on shifts in modified Rankin scores (mRS). A cost model was developed including multiple parameters to account for both direct and indirect stroke costs. These were adjusted based upon functional outcome (mRS). The model compared IV tPA with mechanical embolectomy to assess the costs and benefits of both therapies. Direct stroke-related costs included hospitalization, inpatient and outpatient rehabilitation, home care, skilled nursing facilities, and long-term care facility costs. Indirect costs included years of life expectancy lost and lost QALYs. Values for the model cost parameters were derived from numerous resources and functional outcomes were derived from the MR CLEAN study as a reflective sample of LVOs. Direct and indirect costs and benefits for the two treatments were assessed using Microsoft Excel 2013. This cost-benefit model found a cost-benefit of mechanical embolectomy over IV tPA of $163 624.27 per patient and the cost benefit for 50 000 patients on an annual basis is $8 181 213 653.77. If applied widely within the USA, mechanical embolectomy will significantly reduce the direct and indirect financial burden of stroke ($8 billion/50 000 patients). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  15. Insights into the deactivation mechanism of supported tungsten hydride on alumina (W-H/Al2O3) catalyst for the direct conversion of ethylene to propylene

    KAUST Repository

    Mazoyer, Etienne; Szeto, Kaï Chung; Merle, Nicolas; Thivolle-Cazat, Jean; Boyron, Olivier; Basset, Jean-Marie; Nicholas, Christopher P.; Taoufik, Mostafa

    2014-01-01

    Tungsten hydride supported on alumina prepared by the surface organometallic chemistry method is an active precursor for the direct conversion of ethylene to propylene at low temperature and pressure. An extensive contact time study revealed

  16. Effects of patient-directed music intervention on anxiety and sedative exposure in critically ill patients receiving mechanical ventilatory support: a randomized clinical trial.

    Science.gov (United States)

    Chlan, Linda L; Weinert, Craig R; Heiderscheit, Annie; Tracy, Mary Fran; Skaar, Debra J; Guttormson, Jill L; Savik, Kay

    2013-06-12

    Alternatives to sedative medications, such as music, may alleviate the anxiety associated with ventilatory support. To test whether listening to self-initiated patient-directed music (PDM) can reduce anxiety and sedative exposure during ventilatory support in critically ill patients. Randomized clinical trial that enrolled 373 patients from 12 intensive care units (ICUs) at 5 hospitals in the Minneapolis-St Paul, Minnesota, area receiving acute mechanical ventilatory support for respiratory failure between September 2006 and March 2011. Of the patients included in the study, 86% were white, 52% were female, and the mean (SD) age was 59 (14) years. The patients had a mean (SD) Acute Physiology, Age and Chronic Health Evaluation III score of 63 (21.6) and a mean (SD) of 5.7 (6.4) study days. Self-initiated PDM (n = 126) with preferred selections tailored by a music therapist whenever desired while receiving ventilatory support, self-initiated use of noise-canceling headphones (NCH; n = 122), or usual care (n = 125). Daily assessments of anxiety (on 100-mm visual analog scale) and 2 aggregate measures of sedative exposure (intensity and frequency). Patients in the PDM group listened to music for a mean (SD) of 79.8 (126) (median [range], 12 [0-796]) minutes/day. Patients in the NCH group wore the noise-abating headphones for a mean (SD) of 34.0 (89.6) (median [range], 0 [0-916]) minutes/day. The mixed-models analysis showed that at any time point, patients in the PDM group had an anxiety score that was 19.5 points lower (95% CI, -32.2 to -6.8) than patients in the usual care group (P = .003). By the fifth study day, anxiety was reduced by 36.5% in PDM patients. The treatment × time interaction showed that PDM significantly reduced both measures of sedative exposure. Compared with usual care, the PDM group had reduced sedation intensity by -0.18 (95% CI, -0.36 to -0.004) points/day (P = .05) and had reduced frequency by -0.21 (95% CI, -0.37 to -0.05) points/day (P

  17. On the direction of a crack initiated from an orthotropic bi-material notch composed of materials with non-uniform fracture mechanics properties

    Czech Academy of Sciences Publication Activity Database

    Profant, T.; Klusák, Jan; Ševeček, O.; Kotoul, M.

    525-526, č. 1 (2013), s. 545-548 ISSN 1013-9826. [Fracture and Damage Mechanics /11./. Xi'an, 18.09.2012-21.09.2012] R&D Projects: GA ČR GA101/09/1821; GA ČR GAP108/10/2049 Institutional support: RVO:68081723 Keywords : Orthotropic bi-material notch * generalized stress intensity factor * complex potentials Subject RIV: JL - Materials Fatigue, Friction Mechanics

  18. Interfacial microstructure and mechanical property of Ti6Al4V/A6061 dissimilar joint by direct laser brazing without filler metal and groove

    International Nuclear Information System (INIS)

    Song, Zhihua; Nakata, Kazuhiro; Wu, Aiping; Liao, Jinsun

    2013-01-01

    Laser brazing of Ti6Al4V and A6061-T6 alloys with 2 mm thickness was conducted by focusing laser beam on aluminum alloy side, and the effect of laser offset distance on microstructure and mechanical properties of the dissimilar butt joint was investigated. Laser offset has a great influence on the thickness of interfacial intermetallic compound (IMC) layer and the mechanical property of joint. The thickness of interfacial IMC layer is less than 500 nm, and the average tensile strength of the joint reaches 64% of aluminum base material strength, when suitable welding conditions are used. The interfacial IMC is TiAl 3 . The formation of interfacial IMC layer and its effect on mechanical property of the joint are discussed in the present study.

  19. A Simple Catalytic Mechanism for the Direct Coupling of α-Carbonyls with Functionalized Amines: A One-Step Synthesis of Plavix

    OpenAIRE

    Evans, Ryan W.; Zbieg, Jason R.; Zhu, Shaolin; Li, Wei; MacMillan, David W. C.

    2013-01-01

    The direct α-amination of ketones, esters, and aldehydes has been accomplished via copper catalysis. In the presence of catalytic copper(II) bromide, a diverse range of carbonyl and amine substrates undergo fragment coupling to produce synthetically useful α-amino substituted motifs. The transformation is proposed to proceed via a catalytically generated α-bromo carbonyl species; nucleophilic displacement of the bromide by the amine then delivers the α-amino carbonyl adduct while the catalyst...

  20. Oxidation kinetics and mechanisms of four-direction carbon/carbon composites and their components in carbon dioxide at high temperature

    International Nuclear Information System (INIS)

    Qin, Fei; Peng, Li-na; He, Guo-qiang; Li, Jiang

    2013-01-01

    Highlights: •Four-direction C/C composite was fabricated using carbon fibres and coal tar pitches. •Large-sized bulk matrix was prepared using same process as matrix of C/C composites. •A and E a of C/C, bulk matrix and fibres in CO 2 were determined, respectively. •Pressure exponent n was 0.62 in C/C–CO 2 . -- Abstract: Thermogravimetric analysis and scanning electron microscopy were used to study the oxidation kinetics of four-direction carbon/carbon composites and their components (fibres and matrix) in a CO 2 atmosphere at high temperature. The ablation processes were restricted to reaction-limited oxidation. The mass loss rate was estimated for the four-direction carbon/carbon composites and their components within the temperature of range of 600–1400 °C. The pressure exponent for the reaction of carbon/carbon composites and CO 2 was 0.62, and the pre-exponential factor and activation energy for the reactions of CO 2 and the carbon/carbon composites, carbon fibres and matrix were determined, respectively

  1. Precursor directed synthesis - ``molecular'' mechanisms in the Soft Chemistry approaches and their use for template-free synthesis of metal, metal oxide and metal chalcogenide nanoparticles and nanostructures

    Science.gov (United States)

    Seisenbaeva, Gulaim A.; Kessler, Vadim G.

    2014-05-01

    This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials.This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials. To Professor David Avnir on his 65th birthday.

  2. Pyroelectric response mechanism of barium strontium titanate ceramics in dielectric bolometer mode: The underlying essence of the enhancing effect of direct current bias field

    International Nuclear Information System (INIS)

    Mao, Chaoliang; Cao, Sheng; Yan, Shiguang; Yao, Chunhua; Cao, Fei; Wang, Genshui; Dong, Xianlin; Hu, Xu; Yang, Chunli

    2013-01-01

    Pyroelectric response mechanism of Ba 0.70 Sr 0.30 TiO 3 ceramics under dielectric bolometer (DB) mode was investigated by dielectric and pyroelectric properties measurement. The variations of total, intrinsic, and induced pyroelectric coefficients (p tot , p int , p ind ) with temperatures and bias fields were analyzed. p int plays the dominant role to p tot through most of the temperature range and p ind will be slightly higher than p int above T 0 . The essence of the enhancing effect of DC bias field on pyroelectric coefficient can be attributed to the high value of p int . This mechanism is useful for the pyroelectric materials (DB mode) applications.

  3. Mechanical and tribological properties of polymer-derived Si/C/N sub-millimetre thick miniaturized components fabricated by direct casting

    OpenAIRE

    Bakumov Vadym; Blugan Gurdial; Roos Sigfried; Graule Thomas J.; Fakhfouri Vahid; Grossenbacher Jonas; Gullo Maurizio Rosario; Kiefer Thomas C.; Brugger Juergen; Parlinska Magdalena; Kuebler Jakob

    2012-01-01

    The utilization of silicon based polymers as a source of amorphous non oxide ceramics obtained upon pyrolytic treatment of them is increasingly gaining attention in research and is currently expanding into the field of commercial products. This work is focused on the near net shaped fabrication mechanical and tribological properties of a polymer derived Si/C/N system. Small sub millimetre thick ceramic test discs and bars were fabricated by casting of polysilazane and/or polycarbosilane precu...

  4. The CDM Superfamily Protein MBC Directs Myoblast Fusion through a Mechanism That Requires Phosphatidylinositol 3,4,5-Triphosphate Binding but Is Independent of Direct Interaction with DCrk▿§

    Science.gov (United States)

    Balagopalan, Lakshmi; Chen, Mei-Hui; Geisbrecht, Erika R.; Abmayr, Susan M.

    2006-01-01

    myoblast city (mbc), a member of the CDM superfamily, is essential in the Drosophila melanogaster embryo for fusion of myoblasts into multinucleate fibers. Using germ line clones in which both maternal and zygotic contributions were eliminated and rescue of the zygotic loss-of-function phenotype, we established that mbc is required in the fusion-competent subset of myoblasts. Along with its close orthologs Dock180 and CED-5, MBC has an SH3 domain at its N terminus, conserved internal domains termed DHR1 and DHR2 (or “Docker”), and C-terminal proline-rich domains that associate with the adapter protein DCrk. The importance of these domains has been evaluated by the ability of MBC mutations and deletions to rescue the mbc loss-of-function muscle phenotype. We demonstrate that the SH3 and Docker domains are essential. Moreover, ethyl methanesulfonate-induced mutations that change amino acids within the MBC Docker domain to residues that are conserved in other CDM family members nevertheless eliminate MBC function in the embryo, which suggests that these sites may mediate interactions specific to Drosophila MBC. A functional requirement for the conserved DHR1 domain, which binds to phosphatidylinositol 3,4,5-triphosphate, implicates phosphoinositide signaling in myoblast fusion. Finally, the proline-rich C-terminal sites mediate strong interactions with DCrk, as expected. These sites are not required for MBC to rescue the muscle loss-of-function phenotype, however, which suggests that MBC's role in myoblast fusion can be carried out independently of direct DCrk binding. PMID:17030600

  5. Effect of Mas-related gene (Mrg) receptors on hyperalgesia in rats with CFA-induced inflammation via direct and indirect mechanisms.

    Science.gov (United States)

    Jiang, Jianping; Wang, Dongmei; Zhou, Xiaolong; Huo, Yuping; Chen, Tingjun; Hu, Fenjuan; Quirion, Rémi; Hong, Yanguo

    2013-11-01

    Mas oncogene-related gene (Mrg) receptors are exclusively distributed in small-sized neurons in trigeminal and dorsal root ganglia (DRG). We investigated the effects of MrgC receptor activation on inflammatory hyperalgesia and its mechanisms. A selective MrgC receptor agonist, bovine adrenal medulla peptide 8-22 (BAM8-22) or melanocyte-stimulating hormone (MSH) or the μ-opioid receptor (MOR) antagonist CTAP was administered intrathecally (i.t.) in rats injected with complete Freund's adjuvant (CFA) in one hindpaw. Thermal and mechanical nociceptive responses were assessed. Neurochemicals were measured by immunocytochemistry, Western blot, ELISA and RT-PCR. CFA injection increased mRNA for MrgC receptors in lumbar DRG. BAM8-22 or MSH, given i.t., generated instant short and delayed long-lasting attenuations of CFA-induced thermal hyperalgesia, but not mechanical allodynia. These effects were associated with decreased up-regulation of neuronal NOS (nNOS), CGRP and c-Fos expression in the spinal dorsal horn and/or DRG. However, i.t. administration of CTAP blocked the induction by BAM8-22 of delayed anti-hyperalgesia and inhibition of nNOS and CGRP expression in DRG. BAM8-22 also increased mRNA for MORs and pro-opiomelanocortin, along with β-endorphin content in the lumbar spinal cord and/or DRG. MrgC receptors and nNOS were co-localized in DRG neurons. Activation of MrgC receptors suppressed up-regulation of pronociceptive mediators and consequently inhibited inflammatory pain, because of the activation of up-regulated MrgC receptors and subsequent endogenous activity at MORs. The uniquely distributed MrgC receptors could be a novel target for relieving inflammatory pain. © 2013 The British Pharmacological Society.

  6. The regulatory mechanism of fruit ripening revealed by analyses of direct targets of the tomato MADS-box transcription factor RIPENING INHIBITOR

    Science.gov (United States)

    Fujisawa, Masaki; Ito, Yasuhiro

    2013-01-01

    The developmental process of ripening is unique to fleshy fruits and a key factor in fruit quality. The tomato (Solanum lycopersicum) MADS-box transcription factor RIPENING INHIBITOR (RIN), one of the earliest-acting ripening regulators, is required for broad aspects of ripening, including ethylene-dependent and -independent pathways. However, our knowledge of direct RIN target genes has been limited, considering the broad effects of RIN on ripening. In a recent work published in The Plant Cell, we identified 241 direct RIN target genes by chromatin immunoprecipitation coupled with DNA microarray (ChIP-chip) and transcriptome analysis. Functional classification of the targets revealed that RIN participates in the regulation of many biological processes including well-known ripening processes such as climacteric ethylene production and lycopene accumulation. In addition, we found that ethylene is required for the full expression of RIN and several RIN-targeting transcription factor genes at the ripening stage. Here, based on our recently published findings and additional data, we discuss the ripening processes regulated by RIN and the interplay between RIN and ethylene. PMID:23518588

  7. Microstructure and mechanical properties of Al–1Mn and Al–10Si alloy circular clad ingot prepared by direct chill casting

    International Nuclear Information System (INIS)

    Fu, Ying; Jie, Jinchuan; Wu, Li; Park, Joonpyo; Sun, Jianbo; Kim, Jongho; Li, Tingju

    2013-01-01

    An innovative direct chill casting process to prepare Al–10 wt%Si and Al–1 wt%Mn alloy circular clad ingots has been developed in the present study. The experimental casting parameters were determined by theoretical analysis, numerical simulation and experimental processes. The interface of clad ingots was investigated by methods of metallographic examination, electron probe microanalysis (EPMA) and transmission electron microscopy (TEM). The results showed that excellent metallurgical bonding of two different aluminum alloys could be achieved by direct chill casting. The Al–1Mn alloy which was poured into the mold earlier served as the substrate for heterogeneous nucleation of Al–10Si alloy. Because of diffusion of Si and Mn elements, a diffusion layer with a thickness of about 40 μm on average between the Al–10Si and Al–1Mn alloys could be obtained. The tensile strength of the clad ingot was 106.8 MPa and the fractured position was located in the Al–1Mn alloy side, indicating the strength of the interfacial region is higher than that of Al–1Mn alloy.

  8. Mechanism of Diphtheria Toxin Catalytic Domain Delivery to the Eukaryotic Cell Cytosol and the Cellular Factors that Directly Participate in the Process

    Science.gov (United States)

    Murphy, John R.

    2011-01-01

    Research on diphtheria and anthrax toxins over the past three decades has culminated in a detailed understanding of their structure function relationships (e.g., catalytic (C), transmembrane (T), and receptor binding (R) domains), as well as the identification of their eukaryotic cell surface receptor, an understanding of the molecular events leading to the receptor-mediated internalization of the toxin into an endosomal compartment, and the pH triggered conformational changes required for pore formation in the vesicle membrane. Recently, a major research effort has been focused on the development of a detailed understanding of the molecular interactions between each of these toxins and eukaryotic cell factors that play an essential role in the efficient translocation of their respective catalytic domains through the trans-endosomal vesicle membrane pore and delivery into the cell cytosol. In this review, I shall focus on recent findings that have led to a more detailed understanding of the mechanism by which the diphtheria toxin catalytic domain is delivered to the eukaryotic cell cytosol. While much work remains, it is becoming increasingly clear that the entry process is facilitated by specific interactions with a number of cellular factors in an ordered sequential fashion. In addition, since diphtheria, anthrax lethal factor and anthrax edema factor all carry multiple coatomer I complex binding motifs and COPI complex has been shown to play an essential role in entry process, it is likely that the initial steps in catalytic domain entry of these divergent toxins follow a common mechanism. PMID:22069710

  9. Mechanical characterization of the mouse diaphragm with optical coherence elastography reveals fibrosis-related change of direction-dependent muscle tissue stiffness

    Science.gov (United States)

    Wang, Shang; Loehr, James A.; Larina, Irina V.; Rodney, George G.; Larin, Kirill V.

    2016-03-01

    The diaphragm, composed of skeletal muscle, plays an important role in respiration through its dynamic contraction. Genetic and molecular studies of the biomechanics of mouse diaphragm can provide great insights into an improved understanding and potential treatment of the disorders that lead to diaphragm dysfunction (i.e. muscular dystrophy). However, due to the small tissue size, mechanical assessment of mouse diaphragm tissue under its proper physiological conditions has been challenging. Here, we present the application of noncontact optical coherence elastography (OCE) for quantitative elastic characterization of ex vivo mouse diaphragm. Phase-sensitive optical coherence tomography was combined with a focused air-puff system to capture and measure the elastic wave propagation from tissue surface. Experiments were performed on wildtype and dystrophic mouse diaphragm tissues containing different levels of fibrosis. The OCE measurements of elastic wave propagation were conducted along both the longitudinal and transverse axis of the muscle fibers. Cross-correlation of the temporal displacement profiles from different spatial locations was utilized to obtain the propagation time delay, which was used to calculate the wave group velocity and to further quantify the tissue Young's modulus. Prior to and after OCE assessment, peak tetanic force was measured to monitor viability of the tissue during the elasticity measurements. Our experimental results indicate a positive correlation between fibrosis level and tissue stiffness, suggesting this elastic-wave-based OCE method could be a useful tool to monitor mechanical properties of skeletal muscle under physiological and pathological conditions.

  10. STUDY ON WORKING MECHANISM OF DIRECTIONAL EFFICIENTVERTICAL AXIS WIND TURBINE%定向高效垂直轴风力机工作机理研究

    Institute of Scientific and Technical Information of China (English)

    文恒; 塔娜; 刘金涛; 郝中保

    2016-01-01

    垂直轴风力机风能利用率低的原因,是其在顺风一侧获得的能量,在逆风一侧又被消耗掉一部分.本定向高效垂直轴风力机的叶片在叶轮转动过程中也自转,通过调整叶片的迎风角度,在逆风一侧同样也能获得能量.使得定向高效垂直轴风力机的风能利用率提高到50%以上.通过定向机构,可确保叶片在风向改变时始终保持设计工况.定向高效垂直轴风力机风洞模型试验中,在风速5m/s时,无负荷时转速为300r/min.加负荷后,启动风速为5.2m/s,转速为90r/min.%The reason for the low wind energy utilization of vertical axis wind turbine is that the energy gained at the downwind side is partly consumed at the upwind side.The blade of the directional efficient vertical axis wind turbine rotates with the rotation of impeller.The energy can also be gained at the upwind side by adjusting the blade windward angle,and the utilization of wind energy is improved more than 50%.Through directional structure,the blade can keep design conditions when the wind changes.In the wind tunnel test for directional efficient vertical axis wind turbine,no-load rotate speed is 300 r/min when wind speed is 5m/s.With-load rotate speed is 90 r/rain when wind speed is 5.2m/s.

  11. Design and fabrication of light weight current collectors for direct methanol fuel cells using the micro-electro mechanical system technique

    Science.gov (United States)

    Sung, Min-Feng; Kuan, Yean-Der; Chen, Bing-Xian; Lee, Shi-Min

    The direct methanol fuel cell (DMFC) is suitable for portable applications. Therefore, a light weight and small size is desirable. The main objective of this paper is to design and fabricate a light weight current collector for DMFC usage. The light weight current collector mainly consists of a substrate with two thin film metal layers. The substrate of the current collector is an FR4 epoxy plate. The thin film metal layers are accomplished by the thermo coater technique to coat metal powders onto the substrate surfaces. The developed light weight current collectors are further assembled to a single cell DMFC test fixture to measure the cell performance. The results show that the proposed current collectors could even be applied to DMFCs because they are light, thin and low cost and have potential for mass production.

  12. Preintervention lesion remodelling affects operative mechanisms of balloon optimised directional coronary atherectomy procedures: a volumetric study with three dimensional intravascular ultrasound

    Science.gov (United States)

    von Birgelen, C; Mintz, G; de Vrey, E A; Serruys, P; Kimura, T; Nobuyoshi, M; Popma, J; Leon, M; Erbel, R; de Feyter, P J

    2000-01-01

    AIMS—To classify atherosclerotic coronary lesions on the basis of adequate or inadequate compensatory vascular enlargement, and to examine changes in lumen, plaque, and vessel volumes during balloon optimised directional coronary atherectomy procedures in relation to the state of adaptive remodelling before the intervention.
DESIGN—29 lesion segments in 29 patients were examined with intravascular ultrasound before and after successful balloon optimised directional coronary atherectomy procedures, and a validated volumetric intravascular ultrasound analysis was performed off-line to assess the atherosclerotic lesion remodelling and changes in plaque and vessel volumes that occurred during the intervention. Based on the intravascular ultrasound data, lesions were classified according to whether there was inadequate (group I) or adequate (group II) compensatory enlargement.
RESULTS—There was no significant difference in patient and lesion characteristics between groups I and II (n = 10 and 19), including lesion length and details of the intervention. Quantitative coronary angiographic data were similar for both groups. However, plaque and vessel volumes were significantly smaller in group I than in II. In group I, 9 (4)% (mean (SD)) of the plaque volume was ablated, while in group II 16 (11)% was ablated (p = 0.01). This difference was reflected in a lower lumen volume gain in group I than in group II (46 (18) mm3 v 80 (49) mm3 (p atherectomy procedures. Plaque ablation was found to be particularly low in lesions with inadequate compensatory vascular enlargement.


Keywords: intravascular ultrasound; ultrasonics; remodelling; coronary artery disease; atherectomy PMID:10648496

  13. Purification and site-directed mutagenesis of linoleate 9S-dioxygenase-allene oxide synthase of Fusarium oxysporum confirms the oxygenation mechanism.

    Science.gov (United States)

    Chen, Yang; Jernerén, Fredrik; Oliw, Ernst H

    2017-07-01

    Plants and fungi form jasmonic acid from α-linolenic acid. The first two steps of biosynthesis in plants occur by sequential transformation by 13S-lipoxygenase and allene oxide synthase (AOS). The biosynthesis in fungi may follow this classical scheme, but the only fungal AOS discovered so far are cytochromes P450 (CYP) fused to 8- and 9-dioxygenases (DOX). In the present report, we purified recombinant 9S-DOX-AOS of Fusarium oxysporum from cell lysate by cobalt affinity chromatography to near homogeneity and studied key residues by site-directed mutagenesis. Sequence homology with 8R-DOX-linoleate diol synthases (8R-DOX-LDS) suggested that Tyr414 catalyzes hydrogen abstraction and that Cys1051 forms the heme thiolate ligand. Site-directed mutagenesis (Tyr414Phe; Cys1051Ser) led to loss of 9S-DOX and 9S-AOS activities, respectively, but other important residues in the CYP parts of 5,8- and 7,8-LDS or 9R-AOS were not conserved. The UV-visible spectrum of 9S-DOX-AOS showed a Soret band at 409 nm, which shifted to 413 nm in the Cys1051Ser mutant. The 9S-AOS of the Tyr414Phe mutant transformed 9S-hydroperoxides of α-linolenic and linoleic acids to allene oxides/α-ketols, but it did not transform 13-hydroperoxides. We conclude that 9S- and 8R-DOX catalyze hydrogen abstraction at C-11 and C-8, respectively, by homologous Tyr residues. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Effects of Microalloying on the Microstructures and Mechanical Properties of Directionally Solidified Ni-33(at.%)Al-31Cr-3Mo Eutectic Alloys Investigated

    Science.gov (United States)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2002-01-01

    Despite nickel aluminide (NiAl) alloys' attractive combination of oxidation and thermophysical properties, their development as replacements for superalloy airfoils in gas turbine engines has been largely limited by difficulties in developing alloys with an optimum combination of elevated-temperature creep resistance and room-temperature fracture toughness. Alternatively, research has focused on developing directionally solidified NiAl-based in situ eutectic composites composed of NiAl and (Cr,Mo) phases in order to obtain a desirable combination of properties a systematic investigation was undertaken at the NASA Glenn Research Center to examine the effects of small additions of 11 alloying elements (Co, Cu, Fe, Hf, Mn, Nb, Re, Si, Ta, Ti, and Zr) in amounts varying from 0.25 to 1.0 at.% on the elevated-temperature strength and room-temperature fracture toughness of directionally solidified Ni-33Al-31Cr-3Mo eutectic alloy. The alloys were grown at 12.7 mm/hr, where the unalloyed eutectic base alloy exhibited a planar eutectic microstructure. The different microstructures that formed because of these fifth-element additions are included in the table. The additions of these elements even in small amounts resulted in the formation of cellular microstructures, and in some cases, dendrites and third phases were observed. Most of these elemental additions did not improve either the elevated-temperature strength or the room-temperature fracture toughness over that of the base alloy. However, small improvements in the compression strength were observed between 1200 and 1400 K when 0.5 at.% Hf and 0.25 at.% Ti were added to the base alloy. The results of this study suggest that the microalloying of Ni-33Al-31Cr-3Mo will not significantly improve either its elevatedtemperature strength or its room-temperature fracture toughness. Thus, any improvements in these properties must be acquired by changing the processing conditions.

  15. An analysis methodology of degradation by corrosion mechanisms and preventive actions of the negative effects in the NPP circuits with direct impact in the long-term development

    International Nuclear Information System (INIS)

    Dinu, A.

    2010-01-01

    The corrosion mechanisms, implied in the degradation processes of several alloys, preoccupied the scientific world, producers and users of metallic materials, as well. Due to permanent presence of a potential danger, a great importance was given to corrosion evaluation and prevention in power domain, also including the nuclear power. The main activities have as aim the development of techniques and methods of investigation of structural materials corrosion. Also, there were developed methods of chemical investigation of the environment as well as data bases that allow the simulation of several corrosion types, characteristic of different materials systems and/or media. This made possible the prediction of safe operation life of several structural components. In this context, the paper presents the most important results of project with acronym 'PERFORMCOR' developed in the framework of PNCDI II, 'Capacities' Programme, Modulus I, with the aim of ensuring a R and D infrastructure upgrade of 'LADICON' laboratory of INR - Pitesti. (author)

  16. Study of the mechanism of acetonitrile stacking and its application for directly combining liquid-phase microextraction with micellar electrokinetic chromatography.

    Science.gov (United States)

    Sun, Jingru; Feng, Jing; Shi, Ludi; Liu, Laping; He, Hui; Fan, Yingying; Hu, Shibin; Liu, Shuhui

    2016-08-26

    Acetonitrile stacking is an online concentration method that is distinctive due to its inclusion of a high proportion of organic solvent in sample matrices. We previously designed a universal methodology for the combination of liquid-phase microextraction (LPME) and capillary electrophoresis (CE) using acetonitrile stacking and micellar electrokinetic chromatography (MEKC) mode, thereby achieving large-volume injection of the diluted LPME extractant and the online concentration. In this report, the methodology was extended to the analysis of highly substituted hydrophobic chlorophenols in wines using diethyl carbonate as the extractant. Additionally, the mechanism of acetonitrile stacking was studied. The results indicated that the combination of LPME and MEKC exhibited good analytical performance: with ∼40-fold concentration by LPME, a 20-cm (33% of the total length) sample plug injection of an eight-fold dilution of diethyl carbonate with the organic solvent-saline solution produced enrichments higher by a factor of 260-791. Limits of qualification ranged from 5.5 to 16.0ng/mL. Acceptable reproducibilities of lower than 1.8% for migration time and 8.6% for peak areas were obtained. A dual stacking mechanism of acetonitrile stacking was revealed, involving transient isotachophoresis plus pH-junction stacking. The latter was associated with a pH shift induced by the presence of acetonitrile. The pseudo-stationary phase (Brij-35) played an important role in reducing the CE running time by weakening the isotachophoretic migration of the analyte ions following Cl(-) ions. The combination of acetonitrile stacking and nonionic micelle-based MEKC appears to be a perfect match for introducing water-immiscible LPME extractants into an aqueous CE system and can thus significantly expand the application of LPME-CE in green analytical chemistry. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Mechanical analyses on the digital behaviour of the Tokay gecko (Gekko gecko) based on a multi-level directional adhesion model.

    Science.gov (United States)

    Wu, Xuan; Wang, Xiaojie; Mei, Tao; Sun, Shaoming

    2015-07-08

    This paper proposes a multi-level hierarchical model for the Tokay gecko ( Gekko gecko ) adhesive system and analyses the digital behaviour of the G. gecko under macro/meso-level scale. The model describes the structures of G. gecko 's adhesive system from the nano-level spatulae to the sub-millimetre-level lamella. The G. gecko 's seta is modelled using inextensible fibril based on Euler's elastica theorem. Considering the side contact of the spatular pads of the seta on the flat and rigid substrate, the directional adhesion behaviour of the seta has been investigated. The lamella-induced attachment and detachment have been modelled to simulate the active digital hyperextension (DH) and the digital gripping (DG) phenomena. The results suggest that a tiny angular displacement within 0.25° of the lamellar proximal end is necessary in which a fast transition from attachment to detachment or vice versa is induced. The active DH helps release the torque to induce setal non-sliding detachment, while the DG helps apply torque to make the setal adhesion stable. The lamella plays a key role in saving energy during detachment to adapt to its habitat and provides another adhesive function which differs from the friction-dependent setal adhesion system controlled by the dynamic of G. gecko 's body.

  18. Specimen alignment in an axial tensile test of thin films using direct imaging and its influence on the mechanical properties of BeCu

    International Nuclear Information System (INIS)

    Kang, Dong-Joong; Park, Jun-Hyub; Shin, Myung-Soo; Ha, Jong-Eun; Lee, Hak-Joo

    2010-01-01

    This paper proposes a new system for verification of the alignment of loading fixtures and test specimens during tensile testing of thin film with a micrometer size through direct imaging. The novel and reliable image recognition system to evaluate the misalignment between the load train and the specimen axes during tensile test of thin film was developed using digital image processing technology with CCD. The decision of whether alignment of the tensile specimen is acceptable or not is based on a probabilistic analysis through the edge feature extraction of digital imaging. In order to verify the performance of the proposed system and investigate the effect of the misalignment of the specimen on tensile properties, the tensile tests were performed as displacement control in air and at room temperature for metal thin film, the beryllium copper (BeCu) alloys. In the case of the metal thin films, bending stresses caused by misalignment are insignificant because the films are easily bent during tensile tests to eliminate the bending stresses. And it was observed that little effects and scatters on tensile properties occur by stress gradient caused by twisting at in-plane misalignment, and the effects and scatters on tensile properties are insignificant at out-of-plane misalignment, in the case of the BeCu thin film.

  19. Mechanism of adenylate kinase. Demonstration of a functional relationship between aspartate 93 and Mg2+ by site-directed mutagenesis and proton, phosphorus-31, and magnesium-25 NMR

    International Nuclear Information System (INIS)

    Yan, Honggao; Tsai, Mingdaw

    1991-01-01

    Earlier magnetic resonance studies suggested no direct interaction between Mg 2+ ions and adenylate kinase (AK) in the AK·MgATP (adenosine 5'-triphosphate) complex. However, recent NMR studies concluded that the carboxylate of aspartate 119 accepts a hydrogen bond from a water ligand of the bound Mg 2+ ion in the muscle AK · MgATP complex. On the other hand, in the 2.6-angstrom crystal structure of the yeast AK·MgAP 5 A [P 1 , P 5 -bis(5'-adenosyl)pentaphosphate] complex, the Mg 2+ ion is in proximity to aspartate 93. Substitution of Asp-93 with alanine resulted in no change in dissociation constants, 4-fold increases in K m , and a 650-fold decrease in k cat . Notable changes have been observed in the chemical shifts of the aromatic protons of histidine 36 and a few other aromatic residues. However, the results of detailed analyses of the free enzymes and the AK·MgAP 5 A complexes by one- and two-dimensional NMR suggested that the changes are due to localized perturbations. Thus it is concluded that Asp-93 stabilizes the transition state by ca. 3.9 kcal/mol. Other results raised the question of whether Mg 2+ could bind to D93A·nucleotide complexes, which was then probed by 25 MgNMR. The results suggest that Mg 2+ does bind to the D93A·AP 5 A complex, but possibly only weakly

  20. Artesunate Exerts a Direct Effect on Endothelial Cell Activation and NF-κB Translocation in a Mechanism Independent of Plasmodium Killing

    Directory of Open Access Journals (Sweden)

    Mariana C. Souza

    2012-01-01

    Full Text Available Artemisinin and its derivates are an important class of antimalarial drug and are described to possess immunomodulatory activities. Few studies have addressed the effect of artesunate in the murine malaria model or its effect on host immune response during malaria infection. Herein, we study the effect of artesunate treatment and describe an auxiliary mechanism of artesunate in modulating the inflammatory response during experimental malaria infection in mice. Treatment with artesunate did not reduce significantly the parasitemia within 12 h, however, reduced BBB breakdown and TNF-α mRNA expression in the brain tissue of artesunate-treated mice. Conversely, mefloquine treatment was not able to alter clinical features. Notably, artesunate pretreatment failed to modulate the expression of LFA-1 in splenocytes stimulated with parasitized red blood cells (pRBCs in vitro; however, it abrogated the expression of ICAM-1 in pRBC-stimulated endothelial cells. Accordingly, a cytoadherence in vitro assay demonstrated that pRBCs did not adhere to artesunate-treated vascular endothelial cells. In addition, NF-κB nuclear translocation in endothelial cells stimulated with pRBCs was impaired by artesunate treatment. Our results suggest that artesunate is able to exert a protective effect against the P. berghei-induced inflammatory response by inhibiting NF-κB nuclear translocation and the subsequent expression of ICAM-1.

  1. Direct electron-impact mechanism of excitation of mercury monobromide in a double-pulse dielectric-barrier-discharge HgBr lamp

    Science.gov (United States)

    Datsyuk, V. V.; Izmailov, I. A.; Naumov, V. V.; Kochelap, V. A.

    2016-08-01

    In a nonequlibrium plasma of a gas-discharge HgBr lamp, the terminal electronic state of the HgBr(B-X) radiative transition with a peak wavelength of 502 nm remains populated for a relatively long time and is repeatedly excited to the B state in collisions with plasma electrons. This transfer of the HgBr molecules from the ground state X to the excited state B is the main mechanism of formation of the light-emitting molecules especially when the lamp is excited by double current pulses. According to our simulations, due to the electron-induced transitions between HgBr(X) and HgBr(B), the output characteristics of the DBD lamp operating in a double-pulse regime are better than those of the lamp operating in a single-pulse regime. In the considered case, the peak power is calculated to increase by a factor of about 2 and the lamp efficiency increases by about 50%.

  2. The structure and mechanical properties of parts elaborated by direct laser deposition 316L stainless steel powder obtained in various ways

    Science.gov (United States)

    Loginova, I. S.; Solonin, A. N.; Prosviryakov, A. S.; Adisa, S. B.; Khalil, A. M.; Bykovskiy, D. P.; Petrovskiy, V. N.

    2017-12-01

    In this work the morphology, the size and the chemical composition of the powders of steel 316L received by the two methods was studied: fusion dispersion by a gas stream and reduction of metal chlorides with the subsequent plasma atomization of the received powder particles. The powder particles received by the first method have a spherical shape (aspect ratio 1,0-1,2) with an average size of 77 μm and are characterized by the absence of internal porosity. Particles of the powder received by the second method also have a spherical shape and faultless structure, however, their chemical composition may vary in different particles. The average size of particles is 32 μm. Though the obtained powders had different properties, the experimental samples received by DLD technology demonstrated by equally high durability (Ultimate strength is 623±5 and of 623±18 MPa respectively) and plasticity (38 and 41% respectively). It is established that mechanical properties of DLD samples increase for 7-10% after treatment of the surface.

  3. Melt flow and mechanical properties of silica/perfluoropolymer nanocomposites Fabricated by direct melt-compounding without surface modification on nano-silica.

    Science.gov (United States)

    Tanahashi, Mitsuru; Watanabe, Yusuke; Lee, Jeong-Chang; Takeda, Kunihiko; Fujisawa, Toshiharu

    2009-01-01

    The authors have previously developed a novel method for the fabrication of silica/perfluoropolymer nanocomposites, wherein nano-sized silica particles without surface modification were dispersed uniformly through breakdown of loosely packed agglomerates of silica nanoparticles with low fracture strength in a polymer melt during direct melt-compounding. The method consists of two stages; the first stage involves preparation of the loose silica agglomerate, and the second stage involves melt-compounding of a completely hydrophobic perfluoropolymer, PFA (poly(tetrafluoroethylene-co-perfluoropropylvinylether)), with the loose silica agglomerates. By using this simple method without any lipophilic treatment of the silica surfaces, silica nanoparticles with a primary diameter of 190 nm could be dispersed uniformly into the PFA matrix. The main purpose of the present study is to evaluate the melt flow and tensile properties of silica/PFA nanocomposites fabricated by the above method. In order to elucidate the effects of the size of the dispersed silica in the PFA matrix on the properties of the composites, silica/PFA composite samples exhibiting the dispersion of larger-sized silica particle-clusters were fabricated as negative controls of the silica dispersion state. The results obtained under the present experimental conditions showed that the size of the dispersed silica in the PFA matrix exerts a strong influence on the ultimate tensile properties, such as tensile strength and elongation at break, and the melt flow rate (MFR) of the composite materials. The MFR of the silica/PFA nanocomposite became higher than that of the pure PFA without silica addition, although the MFR of the PFA composites containing larger silica particle-clusters became much lower than that of the pure PFA. Furthermore, uniform dispersion of isolated silica nanoparticles was found to improve not only the Young's modulus but also the ultimate tensile properties of the composite.

  4. Left-right symmetry breaking in mice by left-right dynein may occur via a biased chromatid segregation mechanism, without directly involving the Nodal gene

    Energy Technology Data Exchange (ETDEWEB)

    Sauer, Stephan; Klar, Amar J. S., E-mail: sauers@mail.nih.gov, E-mail: klara@mail.nih.gov [Gene Regulation and Chromosome Biology Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD (United States)

    2012-11-16

    Ever since cloning the classic iv (inversedviscerum) mutation identified the “left-right dynein” (lrd) gene in mice, most research on body laterality determination has focused on its function in motile cilia at the node embryonic organizer. This model is attractive, as it links chirality of cilia architecture to asymmetry development. However, lrd is also expressed in blastocysts and embryonic stem cells, where it was shown to bias the segregation of recombined sister chromatids away from each other in mitosis. These data suggested that lrd is part of a cellular mechanism that recognizes and selectively segregates sister chromatids based on their replication history: old “Watson” versus old “Crick” strands. We previously proposed that the mouse left-right axis is established via an asymmetric cell division prior to/or during gastrulation. In this model, left-right dynein selectively segregates epigenetically differentiated sister chromatids harboring a hypothetical “left-right axis development 1” (“lra1”) gene during the left-right axis establishing cell division. Here, asymmetry development would be ultimately governed by the chirality of the cytoskeleton and the DNA molecule. Our model predicts that randomization of chromatid segregation in lrd mutants should produce embryos with 25% situs solitus, 25% situs inversus, and 50% embryonic death due to heterotaxia and isomerism. Here we confirmed this prediction by using two distinct lrd mutant alleles. Other than lrd, thus far Nodal gene is the most upstream function implicated in visceral organs laterality determination. We next tested whether the Nodal gene constitutes the lra1 gene hypothesized in the model by testing mutant’s effect on 50% embryonic lethality observed in lrd mutants. Since Nodal mutation did not suppress lethality, we conclude that Nodal is not equivalent to the lra1 gene. In summary, we describe the origin of 50% lethality in lrd mutant mice not yet explained by any other

  5. Left-right symmetry breaking in mice by left-right dynein may occur via a biased chromatid segregation mechanism, without directly involving the Nodal gene

    Directory of Open Access Journals (Sweden)

    Stephan eSauer

    2012-11-01

    Full Text Available Ever since cloning the classic iv mutation identified the ‘left-right dynein’ (lrd gene in mice, most research on body laterality determination has focused on its function in motile cilia at the node embryonic organizer. This model is attractive, as it links chirality of cilia architecture to asymmetry development. However, lrd is also expressed in blastocysts and embryonic stem cells, where it was shown to bias the segregation of recombined sister chromatids away from each other in mitosis. These data suggested that lrd is part of a cellular mechanism that recognizes and selectively segregates sister chromatids based on their replication history: old ‘Watson’ vs. old ‘Crick’ strands. We previously proposed that the mouse left-right axis is established via an asymmetric cell division prior to/or during gastrulation. In this model, left-right dynein selectively segregates epigenetically differentiated sister chromatids harboring a hypothetical ‘left-right axis development 1’ (‘lra1’ gene during the left-right axis establishing cell division. Here, asymmetry development would be ultimately governed by the chirality of the cytoskeleton and the DNA molecule. Our model predicts that randomization of chromatid segregation in lrd mutants should produce embryos with 25% situs solitus, 25% situs inversus, and 50% embryonic death due to heterotaxia and isomerism. Here we confirmed this prediction by using two distinct lrd mutant alleles. Other than lrd, thus far Nodal gene is the most upstream function implicated in visceral organs laterality determination. We next tested whether the Nodal gene constitutes the lra1 gene hypothesized in the model by testing mutant’s effect on 50% embryonic lethality observed in lrd mutants. Since Nodal mutation did not suppress lethality, we conclude that Nodal is not equivalent to the lra1 gene. In summary, we describe the origin of 50% lethality in lrd mutant mice not yet explained by any other

  6. Left-right symmetry breaking in mice by left-right dynein may occur via a biased chromatid segregation mechanism, without directly involving the Nodal gene

    International Nuclear Information System (INIS)

    Sauer, Stephan; Klar, Amar J. S.

    2012-01-01

    Ever since cloning the classic iv (inversedviscerum) mutation identified the “left-right dynein” (lrd) gene in mice, most research on body laterality determination has focused on its function in motile cilia at the node embryonic organizer. This model is attractive, as it links chirality of cilia architecture to asymmetry development. However, lrd is also expressed in blastocysts and embryonic stem cells, where it was shown to bias the segregation of recombined sister chromatids away from each other in mitosis. These data suggested that lrd is part of a cellular mechanism that recognizes and selectively segregates sister chromatids based on their replication history: old “Watson” versus old “Crick” strands. We previously proposed that the mouse left-right axis is established via an asymmetric cell division prior to/or during gastrulation. In this model, left-right dynein selectively segregates epigenetically differentiated sister chromatids harboring a hypothetical “left-right axis development 1” (“lra1”) gene during the left-right axis establishing cell division. Here, asymmetry development would be ultimately governed by the chirality of the cytoskeleton and the DNA molecule. Our model predicts that randomization of chromatid segregation in lrd mutants should produce embryos with 25% situs solitus, 25% situs inversus, and 50% embryonic death due to heterotaxia and isomerism. Here we confirmed this prediction by using two distinct lrd mutant alleles. Other than lrd, thus far Nodal gene is the most upstream function implicated in visceral organs laterality determination. We next tested whether the Nodal gene constitutes the lra1 gene hypothesized in the model by testing mutant’s effect on 50% embryonic lethality observed in lrd mutants. Since Nodal mutation did not suppress lethality, we conclude that Nodal is not equivalent to the lra1 gene. In summary, we describe the origin of 50% lethality in lrd mutant mice not yet explained by any other

  7. Mathematical modeling of the crack growth in linear elastic isotropic materials by conventional fracture mechanics approaches and by molecular dynamics method: crack propagation direction angle under mixed mode loading

    Science.gov (United States)

    Stepanova, Larisa; Bronnikov, Sergej

    2018-03-01

    The crack growth directional angles in the isotropic linear elastic plane with the central crack under mixed-mode loading conditions for the full range of the mixity parameter are found. Two fracture criteria of traditional linear fracture mechanics (maximum tangential stress and minimum strain energy density criteria) are used. Atomistic simulations of the central crack growth process in an infinite plane medium under mixed-mode loading using Large-scale Molecular Massively Parallel Simulator (LAMMPS), a classical molecular dynamics code, are performed. The inter-atomic potential used in this investigation is Embedded Atom Method (EAM) potential. The plane specimens with initial central crack were subjected to Mixed-Mode loadings. The simulation cell contains 400000 atoms. The crack propagation direction angles under different values of the mixity parameter in a wide range of values from pure tensile loading to pure shear loading in a wide diapason of temperatures (from 0.1 К to 800 К) are obtained and analyzed. It is shown that the crack propagation direction angles obtained by molecular dynamics method coincide with the crack propagation direction angles given by the multi-parameter fracture criteria based on the strain energy density and the multi-parameter description of the crack-tip fields.

  8. Study of signal transduction mechanism of angiotensin 2 receptor by means of site-directed mutagenesis; Bui totsuzen hen'iho wo mochiita anjiotenshin 2 reseputa no joho dentatsu kiko no kaimei

    Energy Technology Data Exchange (ETDEWEB)

    Yamano, Yoshiaki [Tottori University, Tottori (Japan). Faculty of Agriculture

    1998-12-16

    The renin-angiotensin system (RAS) plays an important role in the regulation of blood pressure. In order to clarify the signaling mechanism mediated by angiotensin 2 receptor, Gq-protein binding amino acid residues of this receptor were clarified by site-directed mutagenesis study. Amino acid residues in the carboxyl tail region were changed by alanines, individually. These mutated receptors were expressed stably in CHO cells, and GTP effect and second messenger molecules were determined, and three residues (Y 312, F313 and L 314) in this region were determined to be concerned for the binding of Gq protein. The other signaling systems, Gi, MAP kinase, JAK-STAT mediated, were reported to be concerned for this receptor. Novel drags for high blood pressure therapy would be explored by clarifying these signaling mechanisms. (author)

  9. The mechanism of Acetobacter xylinum cellulose biosynthesis: direction of chain elongation and the role of lipid pyrophosphate intermediates in the cell membrane

    International Nuclear Information System (INIS)

    Han, N.S.; Robyt, J.F.

    1998-01-01

    The biosynthesis of Acetobacter xylinum ATCC 10821 cellulose has been studied with resting cells and a membrane preparation using 14 C-pulse and chase reactions, with d-glucose and UDPGlc, respectively. Cellulose was biosynthesized from UDPGlc, and it was found to be tightly associated with both the cells and the membrane. The cellulose chains could be released from the cells and the membrane preparation by treating at pH 2, 100 C for 20 min. The cellulose chains that were released from the pulse and pulse-chase reactions were purified and separated from any low molecular weight substances by gel chromatography on Bio-Gel P4. They were then reduced with sodium borohydride and hydrolyzed with 4 M trifluoroacetic acid at 121 C for 2 h. Labeled products from the acid hydrolyzates were separated by paper chromatography and found to be d-glucose and d-glucitol. The amount of radioactivity in the products was determined by liquid scintillation counting. It was found that the pulsed products from the resting cells gave a ratio of d-[ 14 C]glucitol to d-[ 14 C]glucose of 1:11, and after chasing, the ratio decreased to 1:36. The pulsed products from the membrane gave a ratio of d-[ 14 C]glucitol to d-[ 14 C]glucose of 1:12, and after chasing for 5 min the ratio decreased to 1:43, and after 10 min, the ratio decreased to 1:66. These results show that the labeled d-glucitol obtained from the reducing end of the cellulose chain is chased into the interior of the cellulose chain during synthesis, showing that the cellulose chain is elongated from the reducing end. An insertion mechanism for the synthesis of cellulose from UDPGlc is proposed that involves lipid pyrophosphate glycosyl intermediates and three membrane enzymes: lipid phosphate:UDPGlc phosphotransferase, cellulose synthase, and lipid pyrophosphate phosphohydrolase. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  10. Fabrication and photocatalytic activity enhanced mechanism of direct Z-scheme g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Bicheng [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Department of Science and Environmental Studies The Hong Kong Institute of Education, Tai Po, N.T., Hong Kong (China); Xia, Pengfei; Li, Yao [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Ho, Wingkei, E-mail: keithho@ied.edu.hk [Department of Science and Environmental Studies The Hong Kong Institute of Education, Tai Po, N.T., Hong Kong (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2017-01-01

    Highlights: • g-C{sub 3}N{sub 4} acted as a support for the in situ growth of β-Ag{sub 2}WO{sub 4}. • g-C{sub 3}N{sub 4} nanosheets inhibited the phase transformation of β-Ag{sub 2}WO{sub 4} to α-Ag{sub 2}WO{sub 4}. • g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} exhibited a superior photocatalytic activity. • A direct Z-scheme photocatalytic mechanism could explain activity enhancement. - Abstract: Herein, a direct Z-scheme graphitic carbon nitride (g-C{sub 3}N{sub 4})/silver tungstate (Ag{sub 2}WO{sub 4}) photocatalyst was prepared by a facile in situ precipitation method using g-C{sub 3}N{sub 4} as a support and silver nitrate as a precursor. X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and elemental mapping demonstrated that β-Ag{sub 2}WO{sub 4} nanoparticles were evenly distributed on the surface of g-C{sub 3}N{sub 4} nanosheets, which acted as a support for the nucleation and growth of β-Ag{sub 2}WO{sub 4} and inhibited the phase transformation of metastable β-Ag{sub 2}WO{sub 4} to stable α-Ag{sub 2}WO{sub 4}. Photocatalytic experiments indicated that the g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} nanocomposite photocatalyst displayed a better photocatalytic activity than pure g-C{sub 3}N{sub 4} and Ag{sub 2}WO{sub 4} toward the degradation of methyl orange. The enhanced photocatalytic performance of g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} could be well explained by a direct Z-scheme photocatalytic mechanism. This mechanism was related to the efficient space separation of photogenerated electron–hole pairs and the great oxidation and reduction capabilities of the g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4} system. This work provided new insights into the design and fabrication of g-C{sub 3}N{sub 4}-based direct Z-scheme photocatalysts.

  11. N-methyl-d-aspartate receptors, learning and memory: chronic intraventricular infusion of the NMDA receptor antagonist d-AP5 interacts directly with the neural mechanisms of spatial learning.

    Science.gov (United States)

    Morris, R G M; Steele, R J; Bell, J E; Martin, S J

    2013-03-01

    Three experiments were conducted to contrast the hypothesis that hippocampal N-methyl-d-aspartate (NMDA) receptors participate directly in the mechanisms of hippocampus-dependent learning with an alternative view that apparent impairments of learning induced by NMDA receptor antagonists arise because of drug-induced neuropathological and/or sensorimotor disturbances. In experiment 1, rats given a chronic i.c.v. infusion of d-AP5 (30 mm) at 0.5 μL/h were selectively impaired, relative to aCSF-infused animals, in place but not cued navigation learning when they were trained during the 14-day drug infusion period, but were unimpaired on both tasks if trained 11 days after the minipumps were exhausted. d-AP5 caused sensorimotor disturbances in the spatial task, but these gradually worsened as the animals failed to learn. Histological assessment of potential neuropathological changes revealed no abnormalities in d-AP5-treated rats whether killed during or after chronic drug infusion. In experiment 2, a deficit in spatial learning was also apparent in d-AP5-treated rats trained on a spatial reference memory task involving two identical but visible platforms, a task chosen and shown to minimise sensorimotor disturbances. HPLC was used to identify the presence of d-AP5 in selected brain areas. In Experiment 3, rats treated with d-AP5 showed a delay-dependent deficit in spatial memory in the delayed matching-to-place protocol for the water maze. These data are discussed with respect to the learning mechanism and sensorimotor accounts of the impact of NMDA receptor antagonists on brain function. We argue that NMDA receptor mechanisms participate directly in spatial learning. © 2013 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  12. Some future directions in computational failure mechanics

    NARCIS (Netherlands)

    Borst, de R.; Carmeliet, J.; Pamin, J.; Sluys, L.J.; Kusters, G.M.A.; Hendriks, M.A.N.

    1994-01-01

    Continuum approaches are reviewed which can properly model localised deformations that act as a precursor to final fracture in quasi-brittle materials. Next, one such higher-order damaging continuum model is combined with a stochastic approach to describe the heterogeneity in quasi-brittle

  13. Cellular Mechanisms of Transcranial Direct Current Stimulation

    Science.gov (United States)

    2016-07-14

    fEPSP responses are significantly (P < 0.05, *) facilitated with +8 V/m fields ( left ) and reduced with -8 V/m ( right ) in three pathways. In each...cortex results in a sustained modulation of synaptic efficacy. A) Schematic of anodal ( left ) and cathodal ( right ) DCS with current flow along the...current stimulation (tDCS) delivered 1day vs . 1week after cerebral ischemia in rats. Brain Res. Zimerman M, Nitsch M, Giraux P, Gerloff C, Cohen LG

  14. Cellular Mechanisms of Transcranial Direct Current Stimulation

    Science.gov (United States)

    2016-07-14

    potentials. The voltage gradient between parallel Ag/AgCl wires is superimposed on a schematic of a sagittal slice of the rat primary motor cortex . From... motor cortex were prepared from male young adult Wistar rats aged 3 to 6 weeks old, which were deeply anesthetized with ketamine (7.4 mg/kg) and xylazine...glass micropipette filled with 0.25 M NaCl, resistance 1-8 MΩ) was placed in either layer II/III or layer V of the rat primary motor cortex (Fig. 11A

  15. Directed line liquids

    International Nuclear Information System (INIS)

    Kamien, R.D.

    1992-01-01

    This thesis is devoted to the study of ensembles of dense directed lines. These lines are principally to be thought of as polymers, though they also have the morphology of flux lines in high temperature superconductors, strings of colloidal spheres in electrorheological fluids and the world lines of quantum mechanical bosons. The authors discuss how directed polymer melts, string-like formations in electrorheological and ferro-fluids, flux lines in high temperature superconductors and the world lines of quantum mechanical bosons all share similar descriptions. They study a continuous transition in all of these systems, and then study the critical mixing properties of binary mixtures of directed polymers through the renormalization group. They predict the exponents for a directed polymer blend consolute point and a novel two-phase superfluid liquid-gas critical point

  16. Directing 101.

    Science.gov (United States)

    Pintoff, Ernest

    Providing an introduction to anyone considering directing as a field of study or career, this book takes a broad look at the process of directing and encourages students and professionals alike to look outside of the movie industry for inspiration. Chapters in the book discuss selecting and acquiring material; budgeting and financing; casting and…

  17. Spinodal Theory: A Common Rupturing Mechanism in Spinodal Dewetting and Surface Directed Phase Separation (Some Technological Aspects: Spatial Correlations and the Significance of Dipole-Quadrupole Interaction in Spinodal Dewetting)

    International Nuclear Information System (INIS)

    Singh, S.P.; Singh, S.P.

    2011-01-01

    The emerging structures in spinodal dewetting of thin nano films and spinodal decomposition of binary mixtures are found to be similar with certain differences attributed to the nonlinearities inherent in the wetting forces. This paper deals with the technological aspects of the spinodal processes by giving a brief account of the theory and to correlate the two phenomena termed as spinodal dewetting of thin nano films and surface-directed phase separation. The MC simulation micrographs at early stage of spinodal dewetting of a (linear) polymer film confined between two hard walls (using FENE potential between the beads on same chain and Morse potential between inter and intra chain beads) show similarities with surface-directed phase separation (using metropolis algorithm) in creation of holes. The spinodal dewetting is also criticized on the basis of global minimization of free energy emerging from dipole-quadrupole interactions. A novel molecular scale-driving mechanism coming from asymmetric interface formation in spinodal processes is also proposed. It can be believed that the modeling done with the films under confinement of two walls works as a classical mathematical Ansatz to the dipole-quadrupole interaction coming from quantum origins and giving rise to lateral interactions in the process reflecting a colossal behavior in thin nano films though weak in nature

  18. Spinodal Theory: A Common Rupturing Mechanism in Spinodal Dewetting and Surface Directed Phase Separation (Some Technological Aspects: Spatial Correlations and the Significance of Dipole-Quadrupole Interaction in Spinodal Dewetting

    Directory of Open Access Journals (Sweden)

    Satya Pal Singh

    2011-01-01

    Full Text Available The emerging structures in spinodal dewetting of thin nano films and spinodal decomposition of binary mixtures are found to be similar with certain differences attributed to the nonlinearities inherent in the wetting forces. This paper deals with the technological aspects of the spinodal processes by giving a brief account of the theory and to correlate the two phenomena termed as spinodal dewetting of thin nanofilms and surface-directed phase separation. The MC simulation micrographs at early stage of spinodal dewetting of a (linear polymer film confined between two hard walls (using FENE potential between the beads on same chain and Morse potential between inter and intra chain beads show similarities with surface-directed phase separation (using metropolis algorithm in creation of holes. The spinodal dewetting is also criticized on the basis of global minimization of free energy emerging from dipole-quadrupole interactions. A novel molecular scale-driving mechanism coming from asymmetric interface formation in spinodal processes is also proposed. It can be believed that the modeling done with the films under confinement of two walls works as a classical mathematical ansatz to the dipole-quadrupole interaction coming from quantum origins and giving rise to lateral interactions in the process reflecting a colossal behavior in thin nano films though weak in nature.

  19. Regulation of T cell activation by HIV-1 accessory proteins: Vpr acts via distinct mechanisms to cooperate with Nef in NFAT-directed gene expression and to promote transactivation by CREB

    International Nuclear Information System (INIS)

    Lahti, Anna L.; Manninen, Aki; Saksela, Kalle

    2003-01-01

    Nef and Vpr are lentiviral accessory proteins that have been implicated in regulation of cellular gene expression. We noticed that Vpr can potentiate Nef-induced activation of nuclear factor of activated T cells (NFAT)-dependent transcription. Unlike Nef, which stimulated calcium signaling to activate NFAT, Vpr functioned farther downstream. Similar to the positive effects of Vpr on most of the transcriptional test systems that we used, potentiation of NFAT-directed gene expression was relatively modest in magnitude (two- to threefold) and depended on the cell cycle-arresting capacity of Vpr. By contrast, we found that Vpr could cause more than fivefold upregulation of cyclic AMP response element (CRE)-directed transcription via a mechanism that did not require Vpr-induced G2/M arrest. This effect, however, was only evident under suboptimal conditions known to lead to serine phosphorylation of the CRE binding factor (CREB) but not to CREB-dependent gene expression. This suggested that Vpr may act by stabilizing interactions with CREB and its transcriptional cofactor CREB binding protein (CBP). Indeed, this effect could be blocked by cotransfection of the adenoviral CBP inhibitor E1A. These results provide additional evidence for cell cycle-independent regulation of gene expression by Vpr and implicate CREB as a potentially important target for Vpr action in HIV-infected host cells

  20. Directing Creativity

    DEFF Research Database (Denmark)

    Darsø, Lotte; Ibbotson, Piers

    2008-01-01

    In this article we argue that leaders facing complex challenges can learn from the arts, specifically that leaders can learn by examining how theatre directors direct creativity through creative constraints. We suggest that perceiving creativity as a boundary phenomenon is helpful for directing it....... Like leaders, who are caught in paradoxical situations where they have to manage production and logistics simultaneously with making space for creativity and innovation, theatre directors need to find the delicate balance between on one hand renewal of perceptions, acting and interaction...... and on the other hand getting ready for the opening night. We conclude that the art of directing creativity is linked to developing competencies of conscious presence, attention and vigilance, whereas the craft of directing creativity concerns communication, framing and choice....

  1. Influence of Electron Molecule Resonant Vibrational Collisions over the Symmetric Mode and Direct Excitation-Dissociation Cross Sections of CO2 on the Electron Energy Distribution Function and Dissociation Mechanisms in Cold Pure CO2 Plasmas.

    Science.gov (United States)

    Pietanza, L D; Colonna, G; Laporta, V; Celiberto, R; D'Ammando, G; Laricchiuta, A; Capitelli, M

    2016-05-05

    A new set of electron-vibrational (e-V) processes linking the first 10 vibrational levels of the symmetric mode of CO2 is derived by using a decoupled vibrational model and inserted in the Boltzmann equation for the electron energy distribution function (eedf). The new eedf and dissociation rates are in satisfactory agreement with the corresponding ones obtained by using the e-V cross sections reported in the database of Hake and Phelps (H-P). Large differences are, on the contrary, found when the experimental dissociation cross sections of Cosby and Helm are inserted in the Boltzman equation. Comparison of the corresponding rates with those obtained by using the low-energy threshold energy, reported in the H-P database, shows differences up to orders of magnitude, which decrease with the increasing of the reduced electric field. In all cases, we show the importance of superelastic vibrational collisions in affecting eedf and dissociation rates either in the direct electron impact mechanism or in the pure vibrational mechanism.

  2. Direct Heat

    Energy Technology Data Exchange (ETDEWEB)

    Lienau, P J

    1990-01-01

    Potential resources and applications of earth heat in the form of geothermal energy are large. United States direct uses amount to 2,100 MWt thermal and worldwide 8,850 MWt above a reference temperature of 35 degrees Celsius. Space and district heating are the major direct uses of geothermal energy. Equipment employed in direct use projects is of standard manufacture and includes downhole and circulation pumps, transmission and distribution pipelines, heat exchangers and convectors, heat pumps and chillers. Direct uses of earth heat discussed are space and district heating, greenhouse heating and fish farming, process and industrial applications. The economic feasibility of direct use projects is governed by site specific factors such as location of user and resource, resource quality, system load factor and load density, as well as financing. Examples are presented of district heating in Klamath Falls, and Elko. Further developments of direct uses of geothermal energy will depend on matching user needs to the resource, and improving load factors and load density.

  3. Analytical mechanics

    CERN Document Server

    Helrich, Carl S

    2017-01-01

    This advanced undergraduate textbook begins with the Lagrangian formulation of Analytical Mechanics and then passes directly to the Hamiltonian formulation and the canonical equations, with constraints incorporated through Lagrange multipliers. Hamilton's Principle and the canonical equations remain the basis of the remainder of the text. Topics considered for applications include small oscillations, motion in electric and magnetic fields, and rigid body dynamics. The Hamilton-Jacobi approach is developed with special attention to the canonical transformation in order to provide a smooth and logical transition into the study of complex and chaotic systems. Finally the text has a careful treatment of relativistic mechanics and the requirement of Lorentz invariance. The text is enriched with an outline of the history of mechanics, which particularly outlines the importance of the work of Euler, Lagrange, Hamilton and Jacobi. Numerous exercises with solutions support the exceptionally clear and concise treatment...

  4. Direct marketing

    Directory of Open Access Journals (Sweden)

    Čičić Muris

    2002-01-01

    Full Text Available Direct Marketing (DM is usually treated as unworthy activity, with actions at the edge of legality and activities minded cheating. Despite obvious problems regarding ethics and privacy threat, DM with its size, importance and role in a concept of integrated marketing communication deserves respect and sufficient analysis and review

  5. Mechanical Material Engineering

    International Nuclear Information System (INIS)

    Kim, Mun Il

    1993-01-01

    This book introduced mechanical material with introduction, basic problems about metal ingredient of machine of metal and alloy, property of metal material mechanical metal material such as categorization of metal material and high tensile structure steel, mechanic design and steel material with three important points on using of steel materials, selection and directions machine structural steel, selection and directions of steel for tool, selection and instruction of special steel like stainless steel and spring steel, nonferrous metal materials and plastic.

  6. The direction of time

    CERN Document Server

    Reichenbach, Hans

    1999-01-01

    Ever a source of philosophical conjecture and debate, the concept of time represents the beating heart of physics. This final work by the distinguished physicist Hans Reichenbach represents the culmination and integration of a lifetime's philosophical contributions and inquiries into the analysis of time. The result is an outstanding overview of such qualitative, or topological, attributes of time as order and direction.Beginning with a discussion of the emotive significance of time, Reichenbach turns to an examination of the time order of mechanics, the time direction of thermodynamics and m

  7. Direct Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Austern, N. [University of Pittsburgh, Pittsburgh, PA (United States)

    1963-01-15

    In order to give a unified presentation of one point of view, these lectures are devoted only to a detailed development of the standard theories of direct reactions, starting from basic principles. Discussion is given of the present status of the theories, of the techniques used for practical calculation, and of possible future developments. The direct interaction (DI) aspects of a reaction are those which involve only a few of the many degrees of freedom of a nucleus. In fact the minimum number of degrees of freedom which must be involved in a reaction are those required to describe the initial and final channels, and DI studies typically consider these degrees of freedom and no others. Because of this simplicity DI theories may be worked out in painstaking detail. DI processes concern only part of the wave function for a problem. The other part involves complicated excitations of many degrees of freedom, and gives the compound nucleus (CN) effects. While it is extremely interesting to learn how to separate DI and CN effects in an orderly manner, if they are both present in a reaction, no suitable method has yet been found. Instead, current work stresses the kinds of reactions and the kinds of final states in which DI effects dominate and in which CN effects may almost be forgotten. The DI cross-sections which are studied are often extremely large, comparable to elastic scattering cross-sections. (author)

  8. Quality comparison of direct digital panoramic radiography and computed radiography panoramic

    Directory of Open Access Journals (Sweden)

    Dariush Goodarzipour

    2013-09-01

    Full Text Available BACKGROUND AND AIM: Digital panoramic X-ray images can be captured using photostimulable phosphors or solid-state detectors (i.e. charge-coupled devices and Flat-Panels. The first category is defined as computed radiography (CR or semi-direct radiography. The second technology that uses solid-state detectors is known as direct digital radiography (DDR. Both of these technologies have their own advantages and disadvantages. One of the most important fields in comparison of these systems is their resultant image quality. The purpose of this study was to compare the subjective image quality of DDR and CR digital panoramic system, and to assess the overall density and contrast of their images. METHODS: 200 patients were randomly allocated to two digital systems: Promax [central control digital (CCD] and XC [photostimulable phosphor plates (PSP]. Image quality was evaluated in six regions on a 3-point scale by three oral and maxillofacial radiologists independently. In addition, observers assessed overall density and contrast of each image on a 3-point scale. RESULTS: Using chi-square test, no statistically significant differences were found (P >0.05 in subjective image quality of anatomic structures between the two radiographic systems. But DDR system outperformed CR system in overall density and contrast of the image. P values for both overall density and contrast of the images was less than 0.001. CONCLUSIONS: The subjective image quality of CR and DDR panoramic systems in specified anatomic regions were found statistically comparable in this study. In overall density and contrast of the radiographs, DDR system proved better than CR system.

  9. Future direction of direct writing

    Science.gov (United States)

    Kim, Nam-Soo; Han, Kenneth N.

    2010-11-01

    Direct write technology using special inks consisting of finely dispersed metal nanoparticles in liquid is receiving an undivided attention in recent years for its wide range of applicability in modern electronic industry. The application of this technology covers radio frequency identification-tag (RFID-tag), flexible-electronics, organic light emitting diodes (OLED) display, e-paper, antenna, bumpers used in flip-chip, underfilling, frit, miniresistance applications and biological uses, artificial dental applications and many more. In this paper, the authors have reviewed various direct write technologies on the market and discussed their advantages and shortfalls. Emphasis has given on microdispensing deposition write (MDDW), maskless mesoscale materials deposition (M3D), and ink-jet technologies. All of these technologies allow printing various patterns without employing a mask or a resist with an enhanced speed with the aid of computer. MDDW and M3D are capable of drawing patterns in three-dimension and MDDW, in particular, is capable of writing nanoinks with high viscosity. However, it is still far away for direct write to be fully implemented in the commercial arena. One of the hurdles to overcome is in manufacturing conductive inks which are chemically and physically stable, capable of drawing patterns with acceptable conductivity, and also capable of drawing patterns with acceptable adhesiveness with the substrates. The authors have briefly discussed problems involved in manufacturing nanometal inks to be used in various writing devices. There are numerous factors to be considered in manufacturing such inks. They are reducing agents, concentrations, oxidation, compact ability allowing good conductivity, and stability in suspension.

  10. Destruction of microcystins (cyanotoxins) by UV-254 nm-based direct photolysis and advanced oxidation processes (AOPs): influence of variable amino acids on the degradation kinetics and reaction mechanisms.

    Science.gov (United States)

    He, Xuexiang; de la Cruz, Armah A; Hiskia, Anastasia; Kaloudis, Triantafyllos; O'Shea, Kevin; Dionysiou, Dionysios D

    2015-05-01

    Hepatotoxic microcystins (MCs) are the most frequently detected group of cyanobacterial toxins. This study investigated the degradation of common MC variants in water, MC-LR, MC-RR, MC-YR and MC-LA, by UV-254 nm-based processes, UV only, UV/H2O2, UV/S2O8(2-) and UV/HSO5(-). Limited direct photolysis of MCs was observed, while the addition of an oxidant significantly improved the degradation efficiency with an order of UV/S2O8(2-) > UV/HSO5(-) > UV/H2O2 at the same initial molar concentration of the oxidant. The removal of MC-LR by UV/H2O2 appeared to be faster than another cyanotoxin, cylindrospermopsin, at either the same initial molar concentration or the same initial organic carbon concentration of the toxin. It suggested a faster reaction of MC-LR with hydroxyl radical, which was further supported by the determined second-order rate constant of MCs with hydroxyl radical. Both isomerization and photohydration byproducts were observed in UV only process for all four MCs; while in UV/H2O2, hydroxylation and diene-Adda double bond cleavage byproducts were detected. The presence of a tyrosine in the structure of MC-YR significantly promoted the formation of monohydroxylation byproduct m/z 1061; while the presence of a second arginine in MC-RR led to the elimination of a guanidine group and the absence of double bond cleavage byproducts. It was therefore demonstrated in this study that the variable amino acids in the structure of MCs influenced not only the degradation kinetics but also the preferable reaction mechanisms. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Mechanics without mechanisms

    Science.gov (United States)

    Eisenthal, Joshua

    2018-05-01

    At the time of Heinrich Hertz's premature death in 1894, he was regarded as one of the leading scientists of his generation. However, the posthumous publication of his treatise in the foundations of physics, Principles of Mechanics, presents a curious historical situation. Although Hertz's book was widely praised and admired, it was also met with a general sense of dissatisfaction. Almost all of Hertz's contemporaries criticized Principles for the lack of any plausible way to construct a mechanism from the "hidden masses" that are particularly characteristic of Hertz's framework. This issue seemed especially glaring given the expectation that Hertz's work might lead to a model of the underlying workings of the ether. In this paper I seek an explanation for why Hertz seemed so unperturbed by the difficulties of constructing such a mechanism. In arriving at this explanation, I explore how the development of Hertz's image-theory of representation framed the project of Principles. The image-theory brings with it an austere view of the "essential content" of mechanics, only requiring a kind of structural isomorphism between symbolic representations and target phenomena. I argue that bringing this into view makes clear why Hertz felt no need to work out the kinds of mechanisms that many of his readers looked for. Furthermore, I argue that a crucial role of Hertz's hypothesis of hidden masses has been widely overlooked. Far from acting as a proposal for the underlying structure of the ether, I show that Hertz's hypothesis ruled out knowledge of such underlying structure.

  12. Soil Mechanics

    DEFF Research Database (Denmark)

    Gottlieb, Sara Wisbech Jacobsen; Hededal, Ole; Foged, Niels Nielsen

    by stress and strain and their behaviour is convergent. Numerical models exist that simulate clay behaviour over time, the majority derived from Perzyna (1966). An empirical expression for the ‘index of viscosity’ was derived by Leinenkugel (1976). This suggests the change of strain rate is proportional......It is widely accepted that there is a connection between the undrained shear strength and the strain rate. Thixotropy and creep behaviour are connected to the mechanical properties of clay. Thixotropy is the ability of clay to recover its shear strength over time when the shear stress is released...... of equilibrium in viscosity over time at a given stress level for a thixotropic fluid. In rheology, this type of material is known as a non-Newtonian thixotropic fluid. A Newtonian fluid has no yield stress, resembling a strictly elastic material; whereas a non-Newtonian fluid cannot be expressed by a direct...

  13. Fracture Mechanics

    International Nuclear Information System (INIS)

    Jang, Dong Il; Jeong, Gyeong Seop; Han, Min Gu

    1992-08-01

    This book introduces basic theory and analytical solution of fracture mechanics, linear fracture mechanics, non-linear fracture mechanics, dynamic fracture mechanics, environmental fracture and fatigue fracture, application on design fracture mechanics, application on analysis of structural safety, engineering approach method on fracture mechanics, stochastic fracture mechanics, numerical analysis code and fracture toughness test and fracture toughness data. It gives descriptions of fracture mechanics to theory and analysis from application of engineering.

  14. Advances in applied mechanics

    CERN Document Server

    Wu, Theodore Y; Wu, Theodore Y

    2000-01-01

    This highly acclaimed series provides survey articles on the present state and future direction of research in important branches of applied solid and fluid mechanics. Mechanics is defined as a branch of physics that focuses on motion and on the reaction of physical systems to internal and external forces.

  15. Temperature profiles from mechanical bathythermograph (MBT) casts from the USS DIRECT in the North Atlantic Ocean in support of the Fleet Observations of Oceanographic Data (FLOOD) project from 1969-11-07 to 1969-11-25 (NODC Accession 6901053)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MBT data were collected from the USS DIRECT in support of the Fleet Observations of Oceanographic Data (FLOOD) project. Data were collected by US Navy; Ships of...

  16. Coherent states associated to the Jacobi group

    International Nuclear Information System (INIS)

    Berceanu, S.

    2007-01-01

    .The coherent states (CS) offer a useful connection between classical and quantum mechanics. In several previous works we have constructed CS attached to the Jacobi group. It is well known that the Jacobi group appears in Quantum Mechanics, Geometric Quantization, Optics. The mathematicians have given the name 'Jacobi group' to the semidirect product of the Heisenberg-Weyl group and the symplectic group. The same group is known to physicists under other names, as the Schroedinger group. Also the name 'Weyl-symplectic' group is used for the same semi-direct product of the Heisenberg-Weyl group and the symplectic group. In this paper we review and discuss some properties of the coherent states associated to the Jacobi group. (author)

  17. Simulation of bulk aerosol direct radiative effects and its climatic feedbacks in South Africa using RegCM4

    Science.gov (United States)

    Tesfaye, M.; Botai, J.; Sivakumar, V.; Mengistu Tsidu, G.; Rautenbach, C. J. deW.; Moja, Shadung J.

    2016-05-01

    In this study, 12 year runs of the Regional Climate Model (RegCM4) have been used to analyze the bulk aerosol radiative effects and its climatic feedbacks in South Africa. Due to the geographical locations where the aerosol potential source regions are situated and the regional dynamics, the South African aerosol spatial-distribution has a unique feature. Across the west and southwest areas, desert dust particles are dominant. However, sulfate and carbonaceous aerosols are primarily distributed over the east and northern regions of the country. Analysis of the Radiative Effects (RE) shows that in South Africa the bulk aerosols play a role in reducing the net radiation absorbed by the surface via enhancing the net radiative heating in the atmosphere. Hence, across all seasons, the bulk aerosol-radiation-climate interaction induced statistically significant positive feedback on the net atmospheric heating rate. Over the western and central parts of South Africa, the overall radiative feedbacks of bulk aerosol predominantly induces statistically significant Cloud Cover (CC) enhancements. Whereas, over the east and southeast coastal areas, it induces minimum reductions in CC. The CC enhancement and RE of aerosols jointly induce radiative cooling at the surface which in turn results in the reduction of Surface Temperature (ST: up to -1 K) and Surface Sensible Heat Flux (SSHF: up to -24 W/m2). The ST and SSHF decreases cause a weakening of the convectively driven turbulences and surface buoyancy fluxes which lead to the reduction of the boundary layer height, surface pressure enhancement and dynamical changes. Throughout the year, the maximum values of direct and semi-direct effects of bulk aerosol were found in areas of South Africa which are dominated by desert dust particles. This signals the need for a strategic regional plan on how to reduce the dust production and monitoring of the dust dispersion as well as it initiate the need of further research on different

  18. Puzzling Mechanisms

    Science.gov (United States)

    van Deventer, M. Oskar

    2009-01-01

    The basis of a good mechanical puzzle is often a puzzling mechanism. This article will introduce some new puzzling mechanisms, like two knots that engage like gears, a chain whose links can be interchanged, and flat gears that do not come apart. It illustrates how puzzling mechanisms can be transformed into real mechanical puzzles, e.g., by…

  19. University Research Program in Robotics - "Technologies for Micro-Electrical-Mechanical Systems in directed Stockpile Work (DSW) Radiation and Campaigns", Final Technical Annual Report, Project Period 9/1/06 - 8/31/07

    Energy Technology Data Exchange (ETDEWEB)

    James S. Tulenko; Carl D. Crane

    2007-12-13

    The University Research Program in Robotics (URPR) is an integrated group of universities performing fundamental research that addresses broad-based robotics and automation needs of the NNSA Directed Stockpile Work (DSW) and Campaigns. The URPR mission is to provide improved capabilities in robotics science and engineering to meet the future needs of all weapon systems and other associated NNSA/DOE activities.

  20. Directive and Non-Directive Movement in Child Therapy.

    Science.gov (United States)

    Krason, Katarzyna; Szafraniec, Grazyna

    1999-01-01

    Presents a new authorship method of child therapy based on visualization through motion. Maintains that this method stimulates motor development and musical receptiveness, and promotes personality development. Suggests that improvised movement to music facilitates the projection mechanism and that directed movement starts the channeling phase.…

  1. Potential theory for directed networks.

    Directory of Open Access Journals (Sweden)

    Qian-Ming Zhang

    Full Text Available Uncovering factors underlying the network formation is a long-standing challenge for data mining and network analysis. In particular, the microscopic organizing principles of directed networks are less understood than those of undirected networks. This article proposes a hypothesis named potential theory, which assumes that every directed link corresponds to a decrease of a unit potential and subgraphs with definable potential values for all nodes are preferred. Combining the potential theory with the clustering and homophily mechanisms, it is deduced that the Bi-fan structure consisting of 4 nodes and 4 directed links is the most favored local structure in directed networks. Our hypothesis receives strongly positive supports from extensive experiments on 15 directed networks drawn from disparate fields, as indicated by the most accurate and robust performance of Bi-fan predictor within the link prediction framework. In summary, our main contribution is twofold: (i We propose a new mechanism for the local organization of directed networks; (ii We design the corresponding link prediction algorithm, which can not only testify our hypothesis, but also find out direct applications in missing link prediction and friendship recommendation.

  2. Potential Theory for Directed Networks

    Science.gov (United States)

    Zhang, Qian-Ming; Lü, Linyuan; Wang, Wen-Qiang; Zhou, Tao

    2013-01-01

    Uncovering factors underlying the network formation is a long-standing challenge for data mining and network analysis. In particular, the microscopic organizing principles of directed networks are less understood than those of undirected networks. This article proposes a hypothesis named potential theory, which assumes that every directed link corresponds to a decrease of a unit potential and subgraphs with definable potential values for all nodes are preferred. Combining the potential theory with the clustering and homophily mechanisms, it is deduced that the Bi-fan structure consisting of 4 nodes and 4 directed links is the most favored local structure in directed networks. Our hypothesis receives strongly positive supports from extensive experiments on 15 directed networks drawn from disparate fields, as indicated by the most accurate and robust performance of Bi-fan predictor within the link prediction framework. In summary, our main contribution is twofold: (i) We propose a new mechanism for the local organization of directed networks; (ii) We design the corresponding link prediction algorithm, which can not only testify our hypothesis, but also find out direct applications in missing link prediction and friendship recommendation. PMID:23408979

  3. Direct catastrophic injury in sports.

    Science.gov (United States)

    Boden, Barry P

    2005-11-01

    Catastrophic sports injuries are rare but tragic events. Direct (traumatic) catastrophic injury results from participating in the skills of a sport, such as a collision in football. Football is associated with the greatest number of direct catastrophic injuries for all major team sports in the United States. Pole vaulting, gymnastics, ice hockey, and football have the highest incidence of direct catastrophic injuries for sports in which males participate. In most sports, the rate of catastrophic injury is higher at the collegiate than at the high school level. Cheerleading is associated with the highest number of direct catastrophic injuries for all sports in which females participate. Indirect (nontraumatic) injury is caused by systemic failure as a result of exertion while participating in a sport. Cardiovascular conditions, heat illness, exertional hyponatremia, and dehydration can cause indirect catastrophic injury. Understanding the common mechanisms of injury and prevention strategies for direct catastrophic injuries is critical in caring for athletes.

  4. Precursor directed synthesis--"molecular" mechanisms in the Soft Chemistry approaches and their use for template-free synthesis of metal, metal oxide and metal chalcogenide nanoparticles and nanostructures.

    Science.gov (United States)

    Seisenbaeva, Gulaim A; Kessler, Vadim G

    2014-06-21

    This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials.

  5. Particle-based methods for multiscale modeling of blood flow in the circulation and in devices: challenges and future directions. Sixth International Bio-Fluid Mechanics Symposium and Workshop March 28-30, 2008 Pasadena, California.

    Science.gov (United States)

    Yamaguchi, Takami; Ishikawa, Takuji; Imai, Y; Matsuki, N; Xenos, Mikhail; Deng, Yuefan; Bluestein, Danny

    2010-03-01

    A major computational challenge for a multiscale modeling is the coupling of disparate length and timescales between molecular mechanics and macroscopic transport, spanning the spatial and temporal scales characterizing the complex processes taking place in flow-induced blood clotting. Flow and pressure effects on a cell-like platelet can be well represented by a continuum mechanics model down to the order of the micrometer level. However, the molecular effects of adhesion/aggregation bonds are on the order of nanometer. A successful multiscale model of platelet response to flow stresses in devices and the ensuing clotting responses should be able to characterize the clotting reactions and their interactions with the flow. This paper attempts to describe a few of the computational methods that were developed in recent years and became available to researchers in the field. They differ from traditional approaches that dominate the field by expanding on prevailing continuum-based approaches, or by completely departing from them, yielding an expanding toolkit that may facilitate further elucidation of the underlying mechanisms of blood flow and the cellular response to it. We offer a paradigm shift by adopting a multidisciplinary approach with fluid dynamics simulations coupled to biophysical and biochemical transport.

  6. Quantum mechanics

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    The book is on quantum mechanics. The emphasis is on the basic concepts and the methodology. The chapters include: Breakdown of classical concepts; Quantum mechanical concepts; Basic postulates of quantum mechanics; solution of problems in quantum mechanics; Simple harmonic oscillator; and Angular Momentum

  7. Continuum mechanics

    CERN Document Server

    Spencer, A J M

    2004-01-01

    The mechanics of fluids and the mechanics of solids represent the two major areas of physics and applied mathematics that meet in continuum mechanics, a field that forms the foundation of civil and mechanical engineering. This unified approach to the teaching of fluid and solid mechanics focuses on the general mechanical principles that apply to all materials. Students who have familiarized themselves with the basic principles can go on to specialize in any of the different branches of continuum mechanics. This text opens with introductory chapters on matrix algebra, vectors and Cartesian ten

  8. Nanoparticles and direct immunosuppression

    Science.gov (United States)

    Ngobili, Terrika A

    2016-01-01

    Targeting the immune system with nanomaterials is an intensely active area of research. Specifically, the capability to induce immunosuppression is a promising complement for drug delivery and regenerative medicine therapies. Many novel strategies for immunosuppression rely on nanoparticles as delivery vehicles for small-molecule immunosuppressive compounds. As a consequence, efforts in understanding the mechanisms in which nanoparticles directly interact with the immune system have been overshadowed. The immunological activity of nanoparticles is dependent on the physiochemical properties of the nanoparticles and its subsequent cellular internalization. As the underlying factors for these reactions are elucidated, more nanoparticles may be engineered and evaluated for inducing immunosuppression and complementing immunosuppressive drugs. This review will briefly summarize the state-of-the-art and developments in understanding how nanoparticles induce immunosuppressive responses, compare the inherent properties of nanomaterials which induce these immunological reactions, and comment on the potential for using nanomaterials to modulate and control the immune system. PMID:27229901

  9. Direct thermal dyes

    Science.gov (United States)

    Ehlinger, Edward

    1990-07-01

    Direct thermal dyes are members of a class of compounds referred to in the imaging industry as color formers or leuco dyes. The oldest members of that class have simple triarylmethane structures, and have been employed for years in various dyeing applications. More complex triarylmethane compounds, such as phthalides and fluorans, are now used in various imaging systems to produce color. Color is derived from all of these compounds via the same mechanism, on a molecular level. That is, an event of activation produces a highly resonating cationic system whose interaction with incident light produces reflected light of a specific color. The activation event in the case of a direct thermal system is the creation of a melt on the paper involving dye and an acidic developer. The three major performance parameters in a thermal system are background color, image density, and image stability. The three major dye physical parameters affecting thermal performance are chemical constituency, purity, and particle size. Those dyes having the best combination of characteristics which can also be manufactured economically dominate the marketplace. Manufacturing high performance dyes for the thermal market involves multi-step, convergent reaction sequences performed on large scale. Intermediates must be manufactured at the right time, and at the right quality to be useful.

  10. The Mechanisms of Pharmacological Preconditioning of the Brain and the Comparative Efficacy of the Drugs — Direct- and Indirect-Acting Glycogen Synthase Kinase-3β Inhibitors: Experimental Study

    Directory of Open Access Journals (Sweden)

    V. V. Likhvantsev

    2012-01-01

    Full Text Available Objective: to investigate the activity of sevoflurane, dalargin, and lithium chloride in protecting the rat brain from total ischemia/reperfusion and to define whether the GSK=3^ deposphorylation contributes to the mechanism of pharmacological preconditioning. Materials and methods. Experiments were carried out on 80 male albino rats in which temporary circulatory arrest (CA was simulated by ligating the cardiovascular fascicle for 10 and 20 minutes. The animals were revived by mechanical ventilation external cardiac massage, and the intratracheal injection of adrenaline (epinephrine, Moscow Endocrinology Plant at a dose of 0.1 mg/kg. Animals were divided into 9 groups and sevorane (sevoflurane, Abbott Laboratories, dalargin (Microgen Research-and-Production Association, or lithium chloride (Sigma Chemical Co. were separately given with and without CA. Brain tissue homogenate specimens were obtained from euthanized animals. The concentration of total glycogen synthase kinase-3^ (GSK-3^ was colorimetrically determined using a Hitachi-557 spectrophotometer (Hitachi Ltd., Japan. The content of phosphorylated GSK-3/3 (pGSK-3^ in brain homogenate was estimated by Western blotting. Results. The total level of GSK-3^ in each group was similar (80—90 relative units and remained unchanged throughout each experiment. Twenty-minute ischemia maximally activated GSK-30 through dephosphorylation. Ten-minute ischemia elevated pGSK-3^ levels by more than 5 times as compared to the baseline value revealing the «training» effect. The quantity of pGSK-3^ was unchanged in the ischemia/perfusion group during sevoflurane insufflation and was decreased by 27% during dalargin administration. Conclusion. The experimental model of total ischemia provided evidence that the test drugs had a pharmacological preconditioning effect on brain neurons. According to their increasing effect, the drugs were arranged in the following order: dalargin < sevoflurane < lithium

  11. Mechanical Ventilation

    Science.gov (United States)

    ... ventilation is a life support treatment. A mechanical ventilator is a machine that helps people breathe when ... to breathe enough on their own. The mechanical ventilator is also called a ventilator , respirator, or breathing ...

  12. Mechanical design

    CERN Document Server

    Risitano, Antonino

    2011-01-01

    METHODOLOGICAL STATEMENT OF ENGINEERING DESIGNApproaches to product design and developmentMechanical design and environmental requirementsPROPERTIES OF ENGINEERING MATERIALSMaterials for mechanical designCharacterization of metalsStress conditionsFatigue of materialsOptimum material selection in mechanical designDESIGN OF MECHANICAL COMPONENTS AND SYSTEMSFailure theoriesHertz theoryLubrificationShafts and bearingsSplines and keysSpringsFlexible machine elementsSpur gearsPress and shrink fitsPressure tubesCouplingsClutchesBrakes

  13. Quantum Mechanics/Molecular Mechanics Modeling of Drug Metabolism

    DEFF Research Database (Denmark)

    Lonsdale, Richard; Fort, Rachel M; Rydberg, Patrik

    2016-01-01

    )-mexiletine in CYP1A2 with hybrid quantum mechanics/molecular mechanics (QM/MM) methods, providing a more detailed and realistic model. Multiple reaction barriers have been calculated at the QM(B3LYP-D)/MM(CHARMM27) level for the direct N-oxidation and H-abstraction/rebound mechanisms. Our calculated barriers......The mechanism of cytochrome P450(CYP)-catalyzed hydroxylation of primary amines is currently unclear and is relevant to drug metabolism; previous small model calculations have suggested two possible mechanisms: direct N-oxidation and H-abstraction/rebound. We have modeled the N-hydroxylation of (R...... indicate that the direct N-oxidation mechanism is preferred and proceeds via the doublet spin state of Compound I. Molecular dynamics simulations indicate that the presence of an ordered water molecule in the active site assists in the binding of mexiletine in the active site...

  14. NLC Mechanical

    Science.gov (United States)

    text only Mechanical Systems.gif (14697 bytes) NLC Home Page NLC Technical SLAC Permanent Magnets Organization Overview The Mechanical Systems Group Organization is shown on the NLC Project Group Organization Chart (Next Linear Collider Technical Web Page). The Mechanical Systems Group operates on a matrixed

  15. Mechanical Kinesiology.

    Science.gov (United States)

    Barham, Jerry N.

    Mechanical kinesiology is defined as a study of the mechanical factors affecting human movement, i.e., applying the physical laws of mechanics to the study of human motor behavior. This textbook on the subject is divided into thirty lessons. Each lesson is organized into three parts: a part on the text proper; a part entitled "study…

  16. Mechanisms Design

    DEFF Research Database (Denmark)

    Restrepo-Giraldo, John Dairo

    2006-01-01

    Most products and machines involve some kind of controlled movement. From window casements to DVD players, from harbor cranes to the shears to prune your garden, all these machines require mechanisms to move. This course intends to provide the analytical and conceptual tools to design such mechan......Most products and machines involve some kind of controlled movement. From window casements to DVD players, from harbor cranes to the shears to prune your garden, all these machines require mechanisms to move. This course intends to provide the analytical and conceptual tools to design...... using criteria such as size, performance parameters, operation environment, etc. Content: Understanding Mechanisms Design (2 weeks) Definitions, mechanisms representations, kinematic diagrams, the four bar linkage, mobility, applications of mechanisms, types of mechanisms, special mechanisms, the design......: equations for various mechanisms. At the end of this module you will be able to analyze existing mechanisms and to describe their movement. Designing mechanisms (7 weeks) Type synthesis and dimensional synthesis, function generation, path generation, three precision points in multi-loop mechanisms...

  17. Discrete mechanics

    CERN Document Server

    Caltagirone, Jean-Paul

    2014-01-01

    This book presents the fundamental principles of mechanics to re-establish the equations of Discrete Mechanics. It introduces physics and thermodynamics associated to the physical modeling.  The development and the complementarity of sciences lead to review today the old concepts that were the basis for the development of continuum mechanics. The differential geometry is used to review the conservation laws of mechanics. For instance, this formalism requires a different location of vector and scalar quantities in space. The equations of Discrete Mechanics form a system of equations where the H

  18. Discrete mechanics

    International Nuclear Information System (INIS)

    Lee, T.D.

    1985-01-01

    This paper reviews the role of time throughout all phases of mechanics: classical mechanics, non-relativistic quantum mechanics, and relativistic quantum theory. As an example of the relativistic quantum field theory, the case of a massless scalar field interacting with an arbitrary external current is discussed. The comparison between the new discrete theory and the usual continuum formalism is presented. An example is given of a two-dimensional random lattice and its duel. The author notes that there is no evidence that the discrete mechanics is more appropriate than the usual continuum mechanics

  19. Why quantum mechanics?

    International Nuclear Information System (INIS)

    Landsberg, P.T.

    1988-01-01

    It is suggested that an oversight occurred in classical mechanics when time-derivatives of observables were treated on the same footing as the undifferentiated observables. Removal of this oversight points in the direction of quantum mechanics. Additional light is thrown on uncertainty relations and on quantum mechanics, as a possible form of a subtle statistical mechanics, by the formulation of a classical uncertainty relation for a very simple model. The existence of universal motion, i.e., of zero-point energy, is lastly made plausible in terms of a gravitational constant which is time-dependent. By these three considerations an attempt is made to link classical and quantum mechanics together more firmly, thus giving a better understanding of the latter

  20. Memory Mechanisms in Grasping

    Science.gov (United States)

    Hesse, Constanze; Franz, Volker H.

    2009-01-01

    The availability of visual information influences the execution of goal-directed movements. This is very prominent in memory conditions, where a delay is introduced between stimulus presentation and execution of the movement. The corresponding effects could be due to a decay of the visual information or to different processing mechanisms used for…

  1. Catalytic mechanisms of direct pyrrole synthesis via dehydrogenative coupling mediated by PNP-Ir or PNN-Ru pincer complexes: Crucial role of proton-transfer shuttles in the PNP-Ir system

    KAUST Repository

    Qu, Shuanglin

    2014-04-02

    Kempe et al. and Milstein et al. have recently advanced the dehydrogenative coupling methodology to synthesize pyrroles from secondary alcohols (e.g., 3) and β-amino alcohols (e.g., 4), using PNP-Ir (1) and PNN-Ru (2) pincer complexes, respectively. We herein present a DFT study to characterize the catalytic mechanism of these reactions. After precatalyst activation to give active 1A/2A, the transformation proceeds via four stages: 1A/2A-catalyzed alcohol (3) dehydrogenation to give ketone (11), base-facilitated C-N coupling of 11 and 4 to form an imine-alcohol intermediate (18), base-promoted cyclization of 18, and catalyst regeneration via H2 release from 1R/2R. For alcohol dehydrogenations, the bifunctional double hydrogen-transfer pathway is more favorable than that via β-hydride elimination. Generally, proton-transfer (H-transfer) shuttles facilitate various H-transfer processes in both systems. Notwithstanding, H-transfer shuttles play a much more crucial role in the PNP-Ir system than in the PNN-Ru system. Without H-transfer shuttles, the key barriers up to 45.9 kcal/mol in PNP-Ir system are too high to be accessible, while the corresponding barriers (<32.0 kcal/mol) in PNN-Ru system are not unreachable. Another significant difference between the two systems is that the addition of alcohol to 1A giving an alkoxo complex is endergonic by 8.1 kcal/mol, whereas the addition to 2A is exergonic by 8.9 kcal/mol. The thermodynamic difference could be the main reason for PNP-Ir system requiring lower catalyst loading than the PNN-Ru system. We discuss how the differences are resulted in terms of electronic and geometric structures of the catalysts and how to use the features in catalyst development. © 2014 American Chemical Society.

  2. Sensitivity of mesoscale modeling of smoke direct radiative effect to the emission inventory: a case study in northern sub-Saharan African region

    International Nuclear Information System (INIS)

    Zhang, Feng; Wang, Jun; Yang, Zhifeng; Ge, Cui; Ichoku, Charles; Hyer, Edward J; Da Silva, Arlindo; Su, Shenjian; Zhang, Xiaoyang; Kondragunta, Shobha; Kaiser, Johannes W; Wiedinmyer, Christine

    2014-01-01

    An ensemble approach is used to examine the sensitivity of smoke loading and smoke direct radiative effect in the atmosphere to uncertainties in smoke emission estimates. Seven different fire emission inventories are applied independently to WRF-Chem model (v3.5) with the same model configuration (excluding dust and other emission sources) over the northern sub-Saharan African (NSSA) biomass-burning region. Results for November and February 2010 are analyzed, respectively representing the start and end of the biomass burning season in the study region. For February 2010, estimates of total smoke emission vary by a factor of 12, but only differences by factors of 7 or less are found in the simulated regional (15°W–42°E, 13°S–17°N) and monthly averages of column PM 2.5 loading, surface PM 2.5 concentration, aerosol optical depth (AOD), smoke radiative forcing at the top-of-atmosphere and at the surface, and air temperature at 2 m and at 700 hPa. The smaller differences in these simulated variables may reflect the atmospheric diffusion and deposition effects to dampen the large difference in smoke emissions that are highly concentrated in areas much smaller than the regional domain of the study. Indeed, at the local scale, large differences (up to a factor of 33) persist in simulated smoke-related variables and radiative effects including semi-direct effect. Similar results are also found for November 2010, despite differences in meteorology and fire activity. Hence, biomass burning emission uncertainties have a large influence on the reliability of model simulations of atmospheric aerosol loading, transport, and radiative impacts, and this influence is largest at local and hourly-to-daily scales. Accurate quantification of smoke effects on regional climate and air quality requires further reduction of emission uncertainties, particularly for regions of high fire concentrations such as NSSA. (paper)

  3. Mechanical drawing

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Ho Seon; Lee, Geun Hui

    2004-04-15

    This book deals with how to read and draw the mechanical drawing, which includes the basic of drawing like purpose, kinds, and criterion, projection, special projection drawing, omission of the figure, section, and types of section, dimensioning method, writing way of allowable limit size, tolerance of regular size, parts list and assembling drawing, fitting, mechanical elements like screw, key, pin, rivet, spring, bearing, pipe, valve, welding, geometric tolerance and mechanical materials.

  4. Classical mechanics

    CERN Document Server

    Benacquista, Matthew J

    2018-01-01

    This textbook provides an introduction to classical mechanics at a level intermediate between the typical undergraduate and advanced graduate level. This text describes the background and tools for use in the fields of modern physics, such as quantum mechanics, astrophysics, particle physics, and relativity. Students who have had basic undergraduate classical mechanics or who have a good understanding of the mathematical methods of physics will benefit from this book.

  5. Mechanical science

    CERN Document Server

    Bolton, W C

    2013-01-01

    This book gives comprehensive coverage of mechanical science for HNC/HND students taking mechanical engineering courses, including all topics likely to be covered in both years of such courses, as well as for first year undergraduate courses in mechanical engineering. It features 500 problems with answers and 200 worked examples. The third edition includes a new section on power transmission and an appendix on mathematics to help students with the basic notation of calculus and solution of differential equations.

  6. Continuum Mechanics

    CERN Document Server

    Romano, Antonio

    2010-01-01

    This book offers a broad overview of the potential of continuum mechanics to describe a wide range of macroscopic phenomena in real-world problems. Building on the fundamentals presented in the authors' previous book, Continuum Mechanics using Mathematica(R), this new work explores interesting models of continuum mechanics, with an emphasis on exploring the flexibility of their applications in a wide variety of fields.Specific topics, which have been chosen to show the power of continuum mechanics to characterize the experimental behavior of real phenomena, include: * various aspects of nonlin

  7. Poly(dl)lactic acid/polyglycolic acid/iron and poly(dl)lactic acid/polyglycolic acid/samarium cobalt composites for use as a delivery mechanism for magnetically directed chondrogenesis

    Science.gov (United States)

    Oppermann, Dean Alan

    Magnetically directed chondrogenesis (MDC) is a fundamental approach to articular cartilage repair. In MDC a magnet is implanted into the subchondral trabecular bone underlying a cartilage defect and used to attract chondrocytes, magnetically tagged with Fe nanoparticles, to the defect site. Pilot studies by Halpern, Crimp and Grande, using solid neodymium (Nd) magnets, indicated optimistic results by producing a hyaline-like articular cartilage after 8 weeks implantation. Since solid Nd magnets introduce long-term biocompatibility issues, the focus of this dissertation was to develop P(dl)A/PGA/Fe and P(dl)A/PGA/SmCo 5 implants for use in MDC. The effect of implant porosity, implant composition and magnetic material (Fe or SmCo5) on the initial and degraded magnetic properties were evaluated. The biocompatibility of P(dl)A/PGA/Fe implants were investigated by implantation into New Zealand white rabbits for 8 weeks. The effect of hydrogen peroxide (H2O2) and ethylene oxide (EO) sterilization techniques on the molecular weight and chemical structure of P(dl)A/PGA polymers were evaluated using gel permeation chromatography and Fourier transform infrared spectroscopy. The effect of implant morphology, size and number on the von Mises stress in the trabecular bone surrounding the implant was evaluated using a finite element model. In general, SmCo5 implants resulted in higher magnetic fields initially and after 8 weeks of degradation than comparable Fe implants. Increases in magnetic field strength were achieved by increasing the volume fraction of magnetic material and by increasing the PGA concentration. The magnetic field strength degradation rate decreased with increases in volume fraction of magnetic material and increases in PLA concentration. Implantation studies indicated that 50/50 P(dl)A/PGA were more bioactive than 75/25 P(dl)A/PGA with an increased cellular response that is specific to bone growth. The compressive strength and elastic modulus of porous

  8. Manejos de cobertura, mecanismos sulcadores e velocidades de operação sobre a semeadura direta da cultura do milho Covering management, furrowing mechanisms and working speed over direct seeding of corn cultivation

    Directory of Open Access Journals (Sweden)

    Emerson Trogello

    2013-03-01

    Full Text Available A palhada de cobertura residual representa o grande diferencial do sistema de semeadura direta, propiciando melhorias nas condições biológicas, químicas e físicas do solo, em contrapartida esta matéria seca residual pode implicar em dificuldades no processo de semeadura, necessitando por vezes de um manejo deste resíduo. O presente trabalho teve por objetivo avaliar o desenvolvimento e produtividade da cultura do milho submetido a diferentes métodos de manejo de palhada, mecanismos sulcadores e velocidades de operação. Utilizou-se o delineamento em blocos ao acaso com parcelas subsubdivididas, composto por 16 tratamentos e quatro repetições, totalizando 64 unidades experimentais. Os tratamentos foram compostos pela combinação entre quatro manejos de palhada (palha gradeada, rolada, triturada e dessecada, dois mecanismos sulcadores (disco duplo e haste sulcadora e duas velocidades de semeadura (4,5 e 7,0 km h-1. Avaliou-se a profundidade de deposição de sementes, área de solo mobilizada, uniformidade de distribuição de sementes, estande inicial de plantas, número de fileiras por espiga, número de grãos por fileira, massa de mil grãos e produtividade da cultura. Os dados obtidos foram submetidos às análises de variância e havendo diferenças significativas, as médias foram comparadas pelo teste de Tukey, a 5% de significância. A velocidade de operação de 7,0 km h-1 apresentou valores de espaçamentos falhos e duplos mais elevados. Os tratamentos empregados não influenciaram os componentes de rendimento da cultura, bem como não se observou diferenças significativas para a produtividade média da cultura de milho.The stubble covering left over represents the biggest difference of the direct seeding cultivation, providing improvement on biological, chemical and physical soil conditions. Nevertheless, the dry matter remaining may difficult the seeding process, demanding additional management of covering. The aim of

  9. Manejos de cobertura, mecanismos sulcadores e velocidades de operação sobre a semeadura direta da cultura do milho Covering management, furrowing mechanisms and working speed over direct seeding of corn cultivation

    Directory of Open Access Journals (Sweden)

    Emerson Trogello

    2013-01-01

    Full Text Available A palhada de cobertura residual representa o grande diferencial do sistema de semeadura direta, propiciando melhorias nas condições biológicas, químicas e físicas do solo, em contrapartida esta matéria seca residual pode implicar em dificuldades no processo de semeadura, necessitando por vezes de um manejo deste resíduo. O presente trabalho teve por objetivo avaliar o desenvolvimento e produtividade da cultura do milho submetido a diferentes métodos de manejo de palhada, mecanismos sulcadores e velocidades de operação. Utilizou-se o delineamento em blocos ao acaso com parcelas subsubdivididas, composto por 16 tratamentos e quatro repetições, totalizando 64 unidades experimentais. Os tratamentos foram compostos pela combinação entre quatro manejos de palhada (palha gradeada, rolada, triturada e dessecada, dois mecanismos sulcadores (disco duplo e haste sulcadora e duas velocidades de semeadura (4,5 e 7,0 km h-1. Avaliou-se a profundidade de deposição de sementes, área de solo mobilizada, uniformidade de distribuição de sementes, estande inicial de plantas, número de fileiras por espiga, número de grãos por fileira, massa de mil grãos e produtividade da cultura. Os dados obtidos foram submetidos às análises de variância e havendo diferenças significativas, as médias foram comparadas pelo teste de Tukey, a 5% de significância. A velocidade de operação de 7,0 km h-1 apresentou valores de espaçamentos falhos e duplos mais elevados. Os tratamentos empregados não influenciaram os componentes de rendimento da cultura, bem como não se observou diferenças significativas para a produtividade média da cultura de milho.The stubble covering left over represents the biggest difference of the direct seeding cultivation, providing improvement on biological, chemical and physical soil conditions. Nevertheless, the dry matter remaining may difficult the seeding process, demanding additional management of covering. The aim of

  10. Semidirect differentiation as a histopathological prognostic parameter in renal cell carcinoma

    International Nuclear Information System (INIS)

    Bartos, V.; Zacharova, O.; Pokorny, D.; Mraz, R.; Mikulas, J.; Laurinc, P.

    2012-01-01

    Renal cell carcinoma (RCC) is currently one of the most frequent urological malignancies. One of the important histological findings, which reflect biological behaviour of RCC and also provide significant prognostic data are sarcomatoid changes of tumor. In our paper we evaluated the incidence of sarcomatoid changes in renal cell carcinomas and their relationship with other clinico-pathological parameters. A study group consisted of 159 cancers from 157 patients (95 men, 62 women) in the age rage from 18 to 82 years. Out of all cases we found 18 carcinomas (11.3%) having varying degrees of sarcomatoid changes. These tumors were obtained from 18 subjects (11 men, 7 women) between 45 and 82 years of age (mean age 69.1 years). Among them, there were 13 conventional clear cell RCCs, 1 papillary RCC, 2 unclassified RCCs and 2 carcinomas, that entirely consisted of sarcomatoid tissue, were classified as sarcomatoid RCCs. Histologically, sarcomatoid component predominantly composed of spindle cells population with varying degrees of anaplasia and sometimes exhibited rhabdoid features. Six cases corresponded to the pathological stage limited to the kidney (pT1 and pT2) and ten cases were diagnosed in pathological stage with extrarenal propagation (pT3 and pT4). Four patients had metastases in the regional lymph nodes. Almost all cancers showed necrosis. Since sarcomatoid changes in RCC are usually associated with negative prognostic parameters and much less favourable prognosis of disease, if present, pathologist must describe them in a biopsy report. From a clinical point of view, these patients require more careful follow-up, as the literature data indicate the majority of them have metastases at the time of diagnosis. (author)

  11. Supplementary income. Direct selling in Germany

    International Nuclear Information System (INIS)

    Roesner, Sven

    2014-01-01

    This document treats, first, of the evolution of the German support mechanisms to renewable energy sources. Then, it presents the legal framework of direct electricity selling (goal, evolution, facilities in concern and eligibility criteria). Next, the operation of direct selling since August 2014 in Germany is presented (producers eligibility, over- and under-production, reference values, income, tariffs). Finally, the perspectives and conditions of direct selling success are summarized in the conclusion

  12. Automotive Mechanics.

    Science.gov (United States)

    Linder, Ralph C.; And Others

    This curriculum guide, which was validated by vocational teachers and mechanics in the field, describes the competencies needed by entry-level automotive mechanics. This guide lists 15 competencies; for each competency, various tasks with their performance objective, student learning experiences, suggested instructional techniques, instructional…

  13. Quantum mechanics

    CERN Document Server

    Rae, Alastair I M

    2016-01-01

    A Thorough Update of One of the Most Highly Regarded Textbooks on Quantum Mechanics Continuing to offer an exceptionally clear, up-to-date treatment of the subject, Quantum Mechanics, Sixth Edition explains the concepts of quantum mechanics for undergraduate students in physics and related disciplines and provides the foundation necessary for other specialized courses. This sixth edition builds on its highly praised predecessors to make the text even more accessible to a wider audience. It is now divided into five parts that separately cover broad topics suitable for any general course on quantum mechanics. New to the Sixth Edition * Three chapters that review prerequisite physics and mathematics, laying out the notation, formalism, and physical basis necessary for the rest of the book * Short descriptions of numerous applications relevant to the physics discussed, giving students a brief look at what quantum mechanics has made possible industrially and scientifically * Additional end-of-chapter problems with...

  14. Respiratory mechanics

    CERN Document Server

    Wilson, Theodore A

    2016-01-01

    This book thoroughly covers each subfield of respiratory mechanics: pulmonary mechanics, the respiratory pump, and flow. It presents the current understanding of the field and serves as a guide to the scientific literature from the golden age of respiratory mechanics, 1960 - 2010. Specific topics covered include the contributions of surface tension and tissue forces to lung recoil, the gravitational deformation of the lung, and the interdependence forces that act on pulmonary airways and blood vessels. The geometry and kinematics of the ribs is also covered in detail, as well as the respiratory action of the external and internal intercostal muscles, the mechanics of the diaphragm, and the quantitative compartmental models of the chest wall is also described. Additionally, flow in the airways is covered thoroughly, including the wave-speed and viscous expiratory flow-limiting mechanisms; convection, diffusion and the stationary front; and the distribution of ventilation. This is an ideal book for respiratory ...

  15. College mechanics

    CERN Document Server

    Şengül, Caner

    2016-01-01

    College Mechanics QueBank has been designed to be different, enthusiastic, interesting and helpful to you. Therefore, it is not just a test bank about mechanics but also it is like a compass in order to find your way in mechanics Each chapter in this book is put in an order to follow a hierarchy of the mechanics topics; from vectors to simple harmonic motion. Throughout the book there are many multiple choice and long answer questions for you to solve. They have been created for YGS, LYS, SAT, IB or other standardized exams in the world because mechanics has no boundaries and so Physics has no country. Learn the main principle of each chapter and explore the daily life applications. Then you can start to solve the questions by planning a problem solving method carefully. Finally, enjoy solving the questions and discover the meachanics of the universe once more.

  16. Fracture Mechanics

    CERN Document Server

    Zehnder, Alan T

    2012-01-01

    Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering.  He teaches applied mechanics and his research t...

  17. Quantum mechanics

    CERN Document Server

    Powell, John L

    2015-01-01

    Suitable for advanced undergraduates, this thorough text focuses on the role of symmetry operations and the essentially algebraic structure of quantum-mechanical theory. Based on courses in quantum mechanics taught by the authors, the treatment provides numerous problems that require applications of theory and serve to supplement the textual material.Starting with a historical introduction to the origins of quantum theory, the book advances to discussions of the foundations of wave mechanics, wave packets and the uncertainty principle, and an examination of the Schrödinger equation that includ

  18. Quantum mechanics

    International Nuclear Information System (INIS)

    Rae, A.I.M.

    1981-01-01

    This book, based on a thirty lecture course given to students at the beginning of their second year, covers the quantum mechanics required by physics undergraduates. Early chapters deal with wave mechanics, including a discussion of the energy states of the hydrogen atom. These are followed by a more formal development of the theory, leading to a discussion of some advanced applications and an introduction to the conceptual problems associated with quantum measurement theory. Emphasis is placed on the fundamentals of quantum mechanics. Problems are included at the end of each chapter. (U.K.)

  19. Indexing mechanisms

    International Nuclear Information System (INIS)

    Wood, A.G.; Parker, G.E.; Berry, R.

    1976-01-01

    It is stated that the indexing mechanism described can be used in a nuclear reactor fuel element inspection rig. It comprises a tubular body adapted to house a canister containing a number of fuel elements located longtitudinally, and has two chucks spaced apart for displacing the fuel elements longitudinally in a stepwise manner, together with a plunger mechanism for displacing them successively into the chucks. A measuring unit is located between the chucks for measuring the diameter of the fuel elements at intervals about their circumferences, and a secondary indexing mechanism is provided for rotating the measuring unit in a stepwise manner. (U.K.)

  20. Robot Mechanisms

    CERN Document Server

    Lenarcic, Jadran; Stanišić, Michael M

    2013-01-01

    This book provides a comprehensive introduction to the area of robot mechanisms, primarily considering industrial manipulators and humanoid arms. The book is intended for both teaching and self-study. Emphasis is given to the fundamentals of kinematic analysis and the design of robot mechanisms. The coverage of topics is untypical. The focus is on robot kinematics. The book creates a balance between theoretical and practical aspects in the development and application of robot mechanisms, and includes the latest achievements and trends in robot science and technology.

  1. Fracture mechanics

    CERN Document Server

    Perez, Nestor

    2017-01-01

    The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing. Explains computational and engineering approaches for solving crack-related problems using straightforward mathematics that facilitate comprehension of the physical meaning of crack growth processes; Expands computational understandin...

  2. Analytical mechanics

    CERN Document Server

    Lemos, Nivaldo A

    2018-01-01

    Analytical mechanics is the foundation of many areas of theoretical physics including quantum theory and statistical mechanics, and has wide-ranging applications in engineering and celestial mechanics. This introduction to the basic principles and methods of analytical mechanics covers Lagrangian and Hamiltonian dynamics, rigid bodies, small oscillations, canonical transformations and Hamilton–Jacobi theory. This fully up-to-date textbook includes detailed mathematical appendices and addresses a number of advanced topics, some of them of a geometric or topological character. These include Bertrand's theorem, proof that action is least, spontaneous symmetry breakdown, constrained Hamiltonian systems, non-integrability criteria, KAM theory, classical field theory, Lyapunov functions, geometric phases and Poisson manifolds. Providing worked examples, end-of-chapter problems, and discussion of ongoing research in the field, it is suitable for advanced undergraduate students and graduate students studying analyt...

  3. Engineering mechanics

    CERN Document Server

    Gross, Dietmar; Schröder, Jörg; Wall, Wolfgang A; Rajapakse, Nimal

    Statics is the first volume of a three-volume textbook on Engineering Mechanics. The authors, using a time-honoured straightforward and flexible approach, present the basic concepts and principles of mechanics in the clearest and simplest form possible to advanced undergraduate engineering students of various disciplines and different educational backgrounds. An important objective of this book is to develop problem solving skills in a systematic manner. Another aim of this volume is to provide engineering students as well as practising engineers with a solid foundation to help them bridge the gap between undergraduate studies on the one hand and advanced courses on mechanics and/or practical engineering problems on the other. The book contains numerous examples, along with their complete solutions. Emphasis is placed upon student participation in problem solving. The contents of the book correspond to the topics normally covered in courses on basic engineering mechanics at universities and colleges. Now in i...

  4. Introduction to continuum mechanics

    CERN Document Server

    Lai, W Michael; Rubin, David

    1996-01-01

    Introduction to Continuum Mechanics is a recently updated and revised text which is perfect for either introductory courses in an undergraduate engineering curriculum or for a beginning graduate course.Continuum Mechanics studies the response of materials to different loading conditions. The concept of tensors is introduced through the idea of linear transformation in a self-contained chapter, and the interrelation of direct notation, indicial notation, and matrix operations is clearly presented. A wide range of idealized materials are considered through simple static and dynamic problems, a

  5. Probabilistic approach to mechanisms

    CERN Document Server

    Sandler, BZ

    1984-01-01

    This book discusses the application of probabilistics to the investigation of mechanical systems. The book shows, for example, how random function theory can be applied directly to the investigation of random processes in the deflection of cam profiles, pitch or gear teeth, pressure in pipes, etc. The author also deals with some other technical applications of probabilistic theory, including, amongst others, those relating to pneumatic and hydraulic mechanisms and roller bearings. Many of the aspects are illustrated by examples of applications of the techniques under discussion.

  6. Direct selling particularities

    OpenAIRE

    Greifová, Daniela

    2009-01-01

    Bachelor thesis is focused on the parcularities of direct selling, self regulation of this industry, multi-level marketing which is the most used sales method in the field of direct selling. The part of the thesis is dedicated to the issue of customer psychology that is very important for achieving success in direct selling. Main goals are to provide readers with the general view of direct selling and analysis of growing possibilities of the industry in the future.

  7. Supersymmetric mechanics

    International Nuclear Information System (INIS)

    Stelle, Kellogg S

    2007-01-01

    With the development of the electronic archives in high-energy physics, there has been increasing questioning of the role of traditional publishing styles, particularly in the production of conference books. One aspect of traditional publishing that still receives wide appreciation, however, is in the production of well-focussed pedagogical material. The present two-volume edition, 'Supersymmetric Mechanics-Vol 1', edited by S Bellucci and 'Supersymmetric Mechanics-Vol 2', edited by S Bellucci, S Ferrara and A Marrani, is a good example of the kind of well-digested presentation that should still find its way into university libraries. This two-volume set presents the material of a set of pedagogical lectures presented at the INFN National Laboratory in Frascati over a two-year period on the subject of supersymmetric mechanics. The articles include the results of discussions with the attending students after the lectures. Overall, this makes for a useful compilation of material on a subject that underlies much of the current effort in supersymmetric approaches to cosmology and the unification programme. The first volume comprises articles on 'A journey through garden algebras' by S Bellucci, S J Gates Jr and E Orazi on linear supermultiplet realizations in supersymmetric mechanics,'Supersymmetric mechanics in superspace' by S Bellucci and S Krivonos, 'Noncommutative mechanics, Landau levels, twistors and Yang-Mills amplitudes' by V P Nair, 'Elements of (super) Hamiltonian formalism' by A Nersessian and 'Matrix mechanics' by C Sochichiu. The second volume consists entirely of a masterful presentation on 'The attractor mechanism and space time singularities' by S Ferrara. This presents a comprehensive and detailed overview of the structure of supersymmetric black hole solutions in supergravity, critical point structure in the scalar field moduli space and the thermodynamic consequences. This second volume alone makes the set a worthwhile addition to the research

  8. Soil Mechanics

    OpenAIRE

    Verruijt, A.

    2010-01-01

    This book is the text for the introductory course of Soil Mechanics in the Department of Civil Engineering of the Delft University of Technology, as I have given from 1980 until my retirement in 2002. It contains an introduction into the major principles and methods of soil mechanics, such as the analysis of stresses, deformations, and stability. The most important methods of determining soil parameters, in the laboratory and in situ, are also described. Some basic principles of applied mecha...

  9. Leaching mechanisms

    International Nuclear Information System (INIS)

    Dougherty, D.R.; Colombo, P.

    1984-01-01

    Sufficient data are lacking to provide a basis for adequately assessing the long term leaching behavior of solidified low level radioactive waste forms in their disposal environment. Although the release of radioactivity from a waste form to an aqueous environment is recognized to be due to one or more mechanisms such as diffusion, dissolution, corrosion or ion exchange, the leaching mechanisms and the factors which control the leaching behavior of waste forms are not fully understood. This study will determine the prevailing mechanisms for a variety of selected LLW solidification agents which are being considered for use by defense and commercial generators and which will cover the broadest possible number of mechanisms. The investigation will proceed by the postulation of mathematical models representative of the prevailing mechanism(s) and the use of statistically designed experiments to test the actual leaching behavior of laborattory samples against the postulated representations. Maximum use of existing leach data in the literature will be made by incorporating literature results into a computerized data base along with the experimental results generated in this task

  10. Directed Energy Weapons

    Science.gov (United States)

    2007-12-01

    future business . In defense systems, the key to future business is the existence of funded programs. Military commanders understand the lethality and...directed energp capabilities that can provide visibiliy into the likey futur business case for sustaining directed energy industry capabilities...the USD (I) staff to be afocalpointfor advocating improvement in all dimensions of directed energy intelligence. - The Director, Defense Inteligence

  11. Direct reciprocity in structured populations.

    Science.gov (United States)

    van Veelen, Matthijs; García, Julián; Rand, David G; Nowak, Martin A

    2012-06-19

    Reciprocity and repeated games have been at the center of attention when studying the evolution of human cooperation. Direct reciprocity is considered to be a powerful mechanism for the evolution of cooperation, and it is generally assumed that it can lead to high levels of cooperation. Here we explore an open-ended, infinite strategy space, where every strategy that can be encoded by a finite state automaton is a possible mutant. Surprisingly, we find that direct reciprocity alone does not lead to high levels of cooperation. Instead we observe perpetual oscillations between cooperation and defection, with defection being substantially more frequent than cooperation. The reason for this is that "indirect invasions" remove equilibrium strategies: every strategy has neutral mutants, which in turn can be invaded by other strategies. However, reciprocity is not the only way to promote cooperation. Another mechanism for the evolution of cooperation, which has received as much attention, is assortment because of population structure. Here we develop a theory that allows us to study the synergistic interaction between direct reciprocity and assortment. This framework is particularly well suited for understanding human interactions, which are typically repeated and occur in relatively fluid but not unstructured populations. We show that if repeated games are combined with only a small amount of assortment, then natural selection favors the behavior typically observed among humans: high levels of cooperation implemented using conditional strategies.

  12. Theory of Mind: Mechanisms, Methods, and New Directions

    Directory of Open Access Journals (Sweden)

    Lindsey Jacquelyn Byom

    2013-08-01

    Full Text Available Theory of Mind (ToM has received significant research attention. Traditional ToM research has provided important understanding of how humans reason about mental states by utilizing shared world knowledge, social cues, and the interpretation of actions, however many current behavioral paradigms are limited to static, third-person protocols. Emerging experimental approaches such as cognitive simulation and simulated social interaction offer opportunities to investigate ToM in interactive, first-person and second-person scenarios while affording greater experimental control. The advantages and limitations of traditional and emerging ToM methodologies are discussed with the intent of advancing the understanding of ToM in socially mediated situations.

  13. Direct ultimate disposal of spent fuel elements. Mechanical equipment tests

    International Nuclear Information System (INIS)

    Filbert, W.; Schrimpf, C.

    1990-02-01

    Simulation of the shaft transport of waste forms is described. Proceeding from a concept of a shaft hoist with a payload of 85 t, the applicability of the state of the art of essential components, such as hoisting machine, cage and hoisting cables, to such payloads is described. For these components a test stand has been planned which meets safety-related regulations. (DG) [de

  14. Benefits, Mechanisms, and New Directions for Teaching Gratitude to Children

    Science.gov (United States)

    Layous, Kristin; Lyubomirsky, Sonja

    2014-01-01

    The present commentary considers the theoretical and applied implications of Froh, Bono, and colleagues' benefit-appraisals intervention to promote gratitude among youth. First, we discuss the developmental competencies that children need to master before they can benefit from this intervention. The target curriculum was successful among 8- to…

  15. Quantum mechanics

    CERN Document Server

    Fitzpatrick, Richard

    2015-01-01

    Quantum mechanics was developed during the first few decades of the twentieth century via a series of inspired guesses made by various physicists, including Planck, Einstein, Bohr, Schroedinger, Heisenberg, Pauli, and Dirac. All these scientists were trying to construct a self-consistent theory of microscopic dynamics that was compatible with experimental observations. The purpose of this book is to present quantum mechanics in a clear, concise, and systematic fashion, starting from the fundamental postulates, and developing the theory in as logical manner as possible. Topics covered in the book include the fundamental postulates of quantum mechanics, angular momentum, time-dependent and time-dependent perturbation theory, scattering theory, identical particles, and relativistic electron theory.

  16. Quantum mechanics

    CERN Document Server

    Ghosh, P K

    2014-01-01

    Quantum mechanics, designed for advanced undergraduate and graduate students of physics, mathematics and chemistry, provides a concise yet self-contained introduction to the formal framework of quantum mechanics, its application to physical problems and the interpretation of the theory. Starting with a review of some of the necessary mathematics, the basic concepts are carefully developed in the text. After building a general formalism, detailed treatment of the standard material - the harmonic oscillator, the hydrogen atom, angular momentum theory, symmetry transformations, approximation methods, identical particle and many-particle systems, and scattering theory - is presented. The concluding chapter discusses the interpretation of quantum mechanics. Some of the important topics discussed in the book are the rigged Hilbert space, deformation quantization, path integrals, coherent states, geometric phases, decoherene, etc. This book is characterized by clarity and coherence of presentation.

  17. Wave Mechanics or Wave Statistical Mechanics

    International Nuclear Information System (INIS)

    Qian Shangwu; Xu Laizi

    2007-01-01

    By comparison between equations of motion of geometrical optics and that of classical statistical mechanics, this paper finds that there should be an analogy between geometrical optics and classical statistical mechanics instead of geometrical mechanics and classical mechanics. Furthermore, by comparison between the classical limit of quantum mechanics and classical statistical mechanics, it finds that classical limit of quantum mechanics is classical statistical mechanics not classical mechanics, hence it demonstrates that quantum mechanics is a natural generalization of classical statistical mechanics instead of classical mechanics. Thence quantum mechanics in its true appearance is a wave statistical mechanics instead of a wave mechanics.

  18. Mechanical seals

    CERN Document Server

    Mayer, E

    1977-01-01

    Mechanical Seals, Third Edition is a source of practical information on the design and use of mechanical seals. Topics range from design fundamentals and test rigs to leakage, wear, friction and power, reliability, and special designs. This text is comprised of nine chapters; the first of which gives a general overview of seals, including various types of seals and their applications. Attention then turns to the fundamentals of seal design, with emphasis on six requirements that must be considered: sealing effectiveness, length of life, reliability, power consumption, space requirements, and c

  19. Statistical mechanics

    CERN Document Server

    Davidson, Norman

    2003-01-01

    Clear and readable, this fine text assists students in achieving a grasp of the techniques and limitations of statistical mechanics. The treatment follows a logical progression from elementary to advanced theories, with careful attention to detail and mathematical development, and is sufficiently rigorous for introductory or intermediate graduate courses.Beginning with a study of the statistical mechanics of ideal gases and other systems of non-interacting particles, the text develops the theory in detail and applies it to the study of chemical equilibrium and the calculation of the thermody

  20. A perspective on direct conversion

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, W. B.

    1963-10-15

    As flowing energy, electricity is sought for its versatility. Its generation from some other flow or release of energy without mechanical power, or even sometimes heat, as intermediary is called direct conversion. The objective is high electrical output for minimum total cost and not always high conversion efficiency. The wide range of techniques embracing cryogenics and hot plasma derives from the special requirements of source, environment and application. Sources include solar and other radiation, nuclear fission and fusion, chemical energy and heat. Environments and applications range from space vehicles to submarines and from giant power networks to isolated buoys and pocket devices. (author)

  1. A perspective on direct conversion

    International Nuclear Information System (INIS)

    Lewis, W.B.

    1963-10-01

    As flowing energy, electricity is sought for its versatility. Its generation from some other flow or release of energy without mechanical power, or even sometimes heat, as intermediary is called direct conversion. The objective is high electrical output for minimum total cost and not always high conversion efficiency. The wide range of techniques embracing cryogenics and hot plasma derives from the special requirements of source, environment and application. Sources include solar and other radiation, nuclear fission and fusion, chemical energy and heat. Environments and applications range from space vehicles to submarines and from giant power networks to isolated buoys and pocket devices. (author)

  2. Mechanical integrity of canisters

    International Nuclear Information System (INIS)

    Nilsson, Fred

    1992-12-01

    This document constitutes the final report from 'SKBs reference group for mechanical integrity of canisters for spent nuclear fuel'. A complete list of all reports initiated by the reference group can be found in the summary report in this document. The main task of the reference group has been to advice SKB regarding the choice (ranking of alternatives) of canister type for different types of storage. The choice should be based on requirements of impermeability for a given time period and identification of possible limiting mechanisms. The main conclusions from the work were: From mechanical point of view, low phosphorous oxygen free copper (Cu-OFP) is a preferred canisters material. It exhibits satisfactory ductility both during tensile and creep testing. The residual stresses in the canisters are of such a magnitude that the estimated time to creep rupture with the data obtained for the Cu-OFP material is essentially infinite. Based on the present knowledge of stress corrosion cracking of copper there appears to be a small risk for such to occur in the projected environment. This risk need some further study. Rock shear movements of the size of 10 cm should pose no direct threat to the integrity of the canisters. Considering mechanical integrity, the composite copper/steel canister is an advantageous alternative. The recommendations for further research included continued studies of the creep properties of copper and of stress corrosion cracking. However, the studies should focus more directly on the design and fabrication aspect of the canister

  3. Fluid mechanics

    International Nuclear Information System (INIS)

    Granger, R.A.

    1985-01-01

    This text offers the most comprehensive approach available to fluid mechanics. The author takes great care to insure a physical understanding of concepts grounded in applied mathematics. The presentation of theory is followed by engineering applications, helping students develop problem-solving skills from the perspective of a professional engineer. Extensive use of detailed examples reinforces the understanding of theoretical concepts

  4. Fluid Mechanics.

    Science.gov (United States)

    Drazin, Philip

    1987-01-01

    Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)

  5. Directed Energy Anechoic Chamber

    Data.gov (United States)

    Federal Laboratory Consortium — The Directed Energy Anechoic Chamber comprises a power anechoic chamber and one transverse electromagnetic cell for characterizing radiofrequency (RF) responses of...

  6. Records Management Directive

    Data.gov (United States)

    Office of Personnel Management — The Office of Personnel Management (OPM) Records Management Directive provides guidelines for the management of OPM records, and identifies the records management...

  7. Quantum-Limited Directional Amplifiers with Optomechanics

    Science.gov (United States)

    Malz, Daniel; Tóth, László D.; Bernier, Nathan R.; Feofanov, Alexey K.; Kippenberg, Tobias J.; Nunnenkamp, Andreas

    2018-01-01

    Directional amplifiers are an important resource in quantum-information processing, as they protect sensitive quantum systems from excess noise. Here, we propose an implementation of phase-preserving and phase-sensitive directional amplifiers for microwave signals in an electromechanical setup comprising two microwave cavities and two mechanical resonators. We show that both can reach their respective quantum limits on added noise. In the reverse direction, they emit thermal noise stemming from the mechanical resonators; we discuss how this noise can be suppressed, a crucial aspect for technological applications. The isolation bandwidth in both is of the order of the mechanical linewidth divided by the amplitude gain. We derive the bandwidth and gain-bandwidth product for both and find that the phase-sensitive amplifier has an unlimited gain-bandwidth product. Our study represents an important step toward flexible, on-chip integrated nonreciprocal amplifiers of microwave signals.

  8. Direct Conversion of Energy.

    Science.gov (United States)

    Corliss, William R.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics…

  9. Decisions Concerning Directional Dependence

    Science.gov (United States)

    von Eye, Alexander; DeShon, Richard P.

    2012-01-01

    In this rejoinder, von Eye and DeShon discuss the decision strategies proposed in their original article ("Directional Dependence in Developmental Research," this issue), as well as the ones proposed by the authors of the commentary (Pornprasertmanit and Little, "Determining Directional Dependency in Causal Associations," this issue). In addition,…

  10. Breakdown of interdependent directed networks.

    Science.gov (United States)

    Liu, Xueming; Stanley, H Eugene; Gao, Jianxi

    2016-02-02

    Increasing evidence shows that real-world systems interact with one another via dependency connectivities. Failing connectivities are the mechanism behind the breakdown of interacting complex systems, e.g., blackouts caused by the interdependence of power grids and communication networks. Previous research analyzing the robustness of interdependent networks has been limited to undirected networks. However, most real-world networks are directed, their in-degrees and out-degrees may be correlated, and they are often coupled to one another as interdependent directed networks. To understand the breakdown and robustness of interdependent directed networks, we develop a theoretical framework based on generating functions and percolation theory. We find that for interdependent Erdős-Rényi networks the directionality within each network increases their vulnerability and exhibits hybrid phase transitions. We also find that the percolation behavior of interdependent directed scale-free networks with and without degree correlations is so complex that two criteria are needed to quantify and compare their robustness: the percolation threshold and the integrated size of the giant component during an entire attack process. Interestingly, we find that the in-degree and out-degree correlations in each network layer increase the robustness of interdependent degree heterogeneous networks that most real networks are, but decrease the robustness of interdependent networks with homogeneous degree distribution and with strong coupling strengths. Moreover, by applying our theoretical analysis to real interdependent international trade networks, we find that the robustness of these real-world systems increases with the in-degree and out-degree correlations, confirming our theoretical analysis.

  11. Mechanical engineering

    International Nuclear Information System (INIS)

    1988-01-01

    The Mechanical Engineering Division provides the other NAC divisions with design and construction services. Items of special mechanical significance are discussed here. The projects which received major design attention during the past year were: a coupling capacitor for SPC2; a bending magnet and solenoid for ECR ion source; a scanner for outer orbits of the SSC; a scattering chamber for an experimental beamline; a beam swinger; a rotary target magazine for isotope production; a robot arm for isotope production; an isotope transport system and a target cooling system for isotope production. The major projects that were under construction are: a magnetic spectrometer; a second injector cyclotron (SPC2) and extensions to the high-energy beamlines. 4 figs

  12. Statistical mechanics

    CERN Document Server

    Schwabl, Franz

    2006-01-01

    The completely revised new edition of the classical book on Statistical Mechanics covers the basic concepts of equilibrium and non-equilibrium statistical physics. In addition to a deductive approach to equilibrium statistics and thermodynamics based on a single hypothesis - the form of the microcanonical density matrix - this book treats the most important elements of non-equilibrium phenomena. Intermediate calculations are presented in complete detail. Problems at the end of each chapter help students to consolidate their understanding of the material. Beyond the fundamentals, this text demonstrates the breadth of the field and its great variety of applications. Modern areas such as renormalization group theory, percolation, stochastic equations of motion and their applications to critical dynamics, kinetic theories, as well as fundamental considerations of irreversibility, are discussed. The text will be useful for advanced students of physics and other natural sciences; a basic knowledge of quantum mechan...

  13. Fracture mechanics

    International Nuclear Information System (INIS)

    Miannay, D.P.

    1995-01-01

    This book entitle ''Fracture Mechanics'', the first one of the monograph ''Materiologie'' is geared to design engineers, material engineers, non destructive inspectors and safety experts. This book covers fracture mechanics in isotropic homogeneous continuum. Only the monotonic static loading is considered. This book intended to be a reference with the current state of the art gives the fundamental of the issues under concern and avoids the developments too complicated or not yet mastered for not making reading cumbersome. The subject matter is organized as going from an easy to a more complicated level and thus follows the chronological evolution in the field. Similarly the microscopic scale is considered before the macroscopic scale, the physical understanding of phenomena linked to the experimental observation of the material preceded the understanding of the macroscopic behaviour of structures. In this latter field the relatively recent contribution of finite element computations with some analogy with the experimental observation is determining. However more sensitive analysis is not skipped

  14. Statistical mechanics

    CERN Document Server

    Jana, Madhusudan

    2015-01-01

    Statistical mechanics is self sufficient, written in a lucid manner, keeping in mind the exam system of the universities. Need of study this subject and its relation to Thermodynamics is discussed in detail. Starting from Liouville theorem gradually, the Statistical Mechanics is developed thoroughly. All three types of Statistical distribution functions are derived separately with their periphery of applications and limitations. Non-interacting ideal Bose gas and Fermi gas are discussed thoroughly. Properties of Liquid He-II and the corresponding models have been depicted. White dwarfs and condensed matter physics, transport phenomenon - thermal and electrical conductivity, Hall effect, Magneto resistance, viscosity, diffusion, etc. are discussed. Basic understanding of Ising model is given to explain the phase transition. The book ends with a detailed coverage to the method of ensembles (namely Microcanonical, canonical and grand canonical) and their applications. Various numerical and conceptual problems ar...

  15. Mechanical engineering

    CERN Document Server

    Darbyshire, Alan

    2010-01-01

    Alan Darbyshire's best-selling text book provides five-star high quality content to a potential audience of 13,000 engineering students. It explains the most popular specialist units of the Mechanical Engineering, Manufacturing Engineering and Operations & Maintenance Engineering pathways of the new 2010 BTEC National Engineering syllabus. This challenging textbook also features contributions from specialist lecturers, ensuring that no stone is left unturned.

  16. Impact Mechanics

    Science.gov (United States)

    Stronge, W. J.

    2004-03-01

    Impact mechanics is concerned with the reaction forces that develop during a collision and the dynamic response of structures to these reaction forces. The subject has a wide range of engineering applications, from designing sports equipment to improving the crashworthiness of automobiles. This book develops several different methodologies for analysing collisions between structures. These range from rigid body theory for structures that are stiff and compact, to vibration and wave analyses for flexible structures. The emphasis is on low-speed impact where damage is local to the small region of contact between the colliding bodies. The analytical methods presented give results that are more robust or less sensitive to initial conditions than have been achieved hitherto. As a text, Impact Mechanics builds upon foundation courses in dynamics and strength of materials. It includes numerous industrially relevant examples and end-of-chapter homework problems drawn from industry and sports. Practising engineers will also find the methods presented in this book useful in calculating the response of a mechanical system to impact.

  17. Directionality of dog vocalizations

    Science.gov (United States)

    Frommolt, Karl-Heinz; Gebler, Alban

    2004-07-01

    The directionality patterns of sound emission in domestic dogs were measured in an anechoic environment using a microphone array. Mainly long-distance signals from four dogs were investigated. The radiation pattern of the signals differed clearly from an omnidirectional one with average differences in sound-pressure level between the frontal and rear position of 3-7 dB depending from the individual. Frequency dependence of directionality was shown for the range from 250 to 3200 Hz. The results indicate that when studying acoustic communication in mammals, more attention should be paid to the directionality pattern of sound emission.

  18. Quantum mechanics

    International Nuclear Information System (INIS)

    Basdevant, J.L.; Dalibard, J.; Joffre, M.

    2008-01-01

    All physics is quantum from elementary particles to stars and to the big-bang via semi-conductors and chemistry. This theory is very subtle and we are not able to explain it without the help of mathematic tools. This book presents the principles of quantum mechanics and describes its mathematical formalism (wave function, Schroedinger equation, quantum operators, spin, Hamiltonians, collisions,..). We find numerous applications in the fields of new technologies (maser, quantum computer, cryptography,..) and in astrophysics. A series of about 90 exercises with their answers is included. This book is based on a physics course at a graduate level. (A.C.)

  19. Fluid mechanics

    International Nuclear Information System (INIS)

    Paraschivoiu, I.; Prud'homme, M.; Robillard, L.; Vasseur, P.

    2003-01-01

    This book constitutes at the same time theoretical and practical base relating to the phenomena associated with fluid mechanics. The concept of continuum is at the base of the approach developed in this work. The general advance proceeds of simple balances of forces as into hydrostatic to more complex situations or inertias, the internal stresses and the constraints of Reynolds are taken into account. This advance is not only theoretical but contains many applications in the form of solved problems, each chapter ending in a series of suggested problems. The major part of the applications relates to the incompressible flows

  20. Reaction mechanisms

    International Nuclear Information System (INIS)

    Nguyen Trong Anh

    1988-01-01

    The 1988 progress report of the Reaction Mechanisms laboratory (Polytechnic School, France), is presented. The research topics are: the valence bond methods, the radical chemistry, the modelling of the transition states by applying geometric constraints, the long range interactions (ion - molecule) in gaseous phase, the reaction sites in gaseous phase and the mass spectroscopy applications. The points of convergence between the investigations of the mass spectroscopy and the theoretical chemistry teams, as well as the purposes guiding the research programs, are discussed. The published papers, the conferences, the congress communications and the thesis, are also reported [fr

  1. Quantum mechanics

    CERN Document Server

    Rae, Alastair I M

    2007-01-01

    PREFACESINTRODUCTION The Photoelectric Effect The Compton Effect Line Spectra and Atomic Structure De Broglie Waves Wave-Particle Duality The Rest of This Book THE ONE-DIMENSIONAL SCHRÖDINGER EQUATIONS The Time-Dependent Schrödinger Equation The Time-Independent Schrödinger Equation Boundary ConditionsThe Infinite Square Well The Finite Square Well Quantum Mechanical Tunneling The Harmonic Oscillator THE THREE-DIMENSIONAL SCHRÖDINGER EQUATIONS The Wave Equations Separation in Cartesian Coordinates Separation in Spherical Polar Coordinates The Hydrogenic Atom THE BASIC POSTULATES OF QUANTUM MEC

  2. Quantum mechanics

    CERN Document Server

    Mandl, Franz

    1992-01-01

    The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition F. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw The Physics of Stars Second Edition A. C. Phillips Computing for Scient

  3. FAA Directives System

    Science.gov (United States)

    1992-08-26

    Consistent with the Federal Aviation Administration's mission to foster a safe, : secure, and efficient aviation system is the need for an effective and efficient : process for communitcating policy and procedures. The FAA Directives System : provide...

  4. Assessing directionality in context

    African Journals Online (AJOL)

    Kate H

    In support of first-language interpreting as the exclusive interpreting direction, ... some light on the possible interaction between two independent variables, .... the “local context” refers to the setting, genre, participants, and aims of the event.

  5. The ''energy tax'' directive

    International Nuclear Information System (INIS)

    Anon.

    2003-01-01

    As Austria dropped its reservation, U.E. Economics and Finance Ministers gave, on 20 March at Brussels, their political agreement to the proposed Directive on a Community framework for the taxation of energy products. (author)

  6. Fluid mechanics fundamentals and applications

    CERN Document Server

    Cengel, Yunus

    2013-01-01

    Cengel and Cimbala's Fluid Mechanics Fundamentals and Applications, communicates directly with tomorrow's engineers in a simple yet precise manner. The text covers the basic principles and equations of fluid mechanics in the context of numerous and diverse real-world engineering examples. The text helps students develop an intuitive understanding of fluid mechanics by emphasizing the physics, using figures, numerous photographs and visual aids to reinforce the physics. The highly visual approach enhances the learning of Fluid mechanics by students. This text distinguishes itself from others by the way the material is presented - in a progressive order from simple to more difficult, building each chapter upon foundations laid down in previous chapters. In this way, even the traditionally challenging aspects of fluid mechanics can be learned effectively. McGraw-Hill is also proud to offer ConnectPlus powered by Maple with the third edition of Cengel/Cimbabla, Fluid Mechanics. This innovative and powerful new sy...

  7. Frontal transcranial direct current stimulation (tDCS) abolishes list-method directed forgetting.

    Science.gov (United States)

    Silas, Jonathan; Brandt, Karen R

    2016-03-11

    It is a point of controversy as to whether directed forgetting effects are a result of active inhibition or a change of context initiated by the instruction to forget. In this study we test the causal role of active inhibition in directed forgetting. By applying cathodal transcranial direct current stimulation (tDCS) over the right prefrontal cortex we suppressed cortical activity commonly associated with inhibitory control. Participants who underwent real brain stimulation before completing the directed forgetting paradigm showed no directed forgetting effects. Conversely, those who underwent sham brain stimulation demonstrated classical directed forgetting effects. We argue that these findings suggest that inhibition is the primary mechanism that results in directed forgetting costs and benefits. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Directed GF-spaces

    Directory of Open Access Journals (Sweden)

    F.G. Arenas

    2001-10-01

    Full Text Available In this paper we introduce the concept of directed fractal structure, which is a generalization of the concept of fractal structure (introduced by the authors. We study the relation with transitive quasiuniformities and inverse limits of posets. We define the concept of GF-compactification and apply it to prove that the Stone-Cech compactification can be obtained as the GF-compactification of the directed fractal structure associated to the Pervin quasi-uniformity.

  9. Formulation and Evaluation of Ascorbic acid Tablets by Direct ...

    African Journals Online (AJOL)

    Formulation and Evaluation of Ascorbic acid Tablets by Direct Compression using Microcrystalline Starch as a Direct Compression Excipient. ... Abstract. PURPOSE: To evaluate the tableting properties of microcrystalline starch (MCS) used as a direct ... RESULTS: Mechanical properties of tablets formulated with MCS were

  10. Describing the direct and indirect radiative effects of atmospheric aerosols over Europe by using coupled meteorology-chemistry simulations: a contribution from the AQMEII-Phase II exercise

    Science.gov (United States)

    Jimenez-Guerrero, Pedro; Balzarini, Alessandra; Baró, Rocío; Curci, Gabriele; Forkel, Renate; Hirtl, Marcus; Honzak, Luka; Langer, Matthias; Pérez, Juan L.; Pirovano, Guido; San José, Roberto; Tuccella, Paolo; Werhahn, Johannes; Zabkar, Rahela

    2014-05-01

    The study of the response of the aerosol levels in the atmosphere to a changing climate and how this affects the radiative budget of the Earth (direct, semi-direct and indirect effects) is an essential topic to build confidence on climate science, since these feedbacks involve the largest uncertainties nowadays. Air quality-climate interactions (AQCI) are, therefore, a key, but uncertain contributor to the anthropogenic forcing that remains poorly understood. To build confidence in the AQCI studies, regional-scale integrated meteorology-atmospheric chemistry models (i.e., models with on-line chemistry) that include detailed treatment of aerosol life cycle and aerosol impacts on radiation (direct effects) and clouds (indirect effects) are in demand. In this context, the main objective of this contribution is the study and definition of the uncertainties in the climate-chemistry-aerosol-cloud-radiation system associated to the direct radiative forcing and the indirect effect caused by aerosols over Europe, using an ensemble of fully-coupled meteorology-chemistry model simulations with the WRF-Chem model run under the umbrella of AQMEII-Phase 2 international initiative. Simulations were performed for Europe for the entire year 2010. According to the common simulation strategy, the year was simulated as a sequence of 2-day time slices. For better comparability, the seven groups applied the same grid spacing of 23 km and shared common processing of initial and boundary conditions as well as anthropogenic and fire emissions. With exception of a simulation with different cloud microphysics, identical physics options were chosen while the chemistry options were varied. Two model set-ups will be considered here: one sub-ensemble of simulations not taking into account any aerosol feedbacks (the baseline case) and another sub-ensemble of simulations which differs from the former by the inclusion of aerosol-radiation feedback. The existing differences for meteorological

  11. Continuum mechanics for engineers

    CERN Document Server

    Mase, G Thomas; Mase, George E

    2009-01-01

    Continuum TheoryContinuum MechanicsStarting OverNotationEssential MathematicsScalars, Vectors and Cartesian TensorsTensor Algebra in Symbolic Notation - Summation ConventionIndicial NotationMatrices and DeterminantsTransformations of Cartesian TensorsPrincipal Values and Principal DirectionsTensor Fields, Tensor CalculusIntegral Theorems of Gauss and StokesStress PrinciplesBody and Surface Forces, Mass DensityCauchy Stress PrincipleThe Stress TensorForce and Moment Equilibrium; Stress Tensor SymmetryStress Transformation LawsPrincipal Stresses; Principal Stress DirectionsMaximum and Minimum Stress ValuesMohr's Circles For Stress Plane StressDeviator and Spherical Stress StatesOctahedral Shear StressKinematics of Deformation and MotionParticles, Configurations, Deformations and MotionMaterial and Spatial CoordinatesLangrangian and Eulerian DescriptionsThe Displacement FieldThe Material DerivativeDeformation Gradients, Finite Strain TensorsInfinitesimal Deformation TheoryCompatibility EquationsStretch RatiosRot...

  12. Boosters and barriers for direct cardiac reprogramming.

    Science.gov (United States)

    Talkhabi, Mahmood; Zonooz, Elmira Rezaei; Baharvand, Hossein

    2017-06-01

    Heart disease is currently the most significant cause of morbidity and mortality worldwide, which accounts for approximately 33% of all deaths. Recently, a promising and alchemy-like strategy has been developed called direct cardiac reprogramming, which directly converts somatic cells such as fibroblasts to cardiac lineage cells such as cardiomyocytes (CMs), termed induced CMs or iCMs. The first in vitro cardiac reprogramming study, mediated by cardiac transcription factors (TFs)-Gata4, Tbx5 and Mef2C-, was not enough efficient to produce an adequate number of fully reprogrammed, functional iCMs. As a result, numerous combinations of cardiac TFs exist for direct cardiac reprogramming of mouse and human fibroblasts. However, the efficiency of direct cardiac reprogramming remains low. Recently, a number of cellular and molecular mechanisms have been identified to increase the efficiency of direct cardiac reprogramming and the quality of iCMs. For example, microgrooved substrate, cardiogenic growth factors [VEGF, FGF, BMP4 and Activin A], and an appropriate stoichiometry of TFs boost the direct cardiac reprogramming. On the other hand, serum, TGFβ signaling, activators of epithelial to mesenchymal transition, and some epigenetic factors (Bmi1 and Ezh2) are barriers for direct cardiac reprogramming. Manipulating these mechanisms by the application of boosters and removing barriers can increase the efficiency of direct cardiac reprogramming and possibly make iCMs reliable for cell-based therapy or other potential applications. In this review, we summarize the latest trends in cardiac TF- or miRNA-based direct cardiac reprogramming and comprehensively discuses all molecular and cellular boosters and barriers affecting direct cardiac reprogramming. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Understand quantum mechanics

    International Nuclear Information System (INIS)

    Omnes, R.

    2000-01-01

    The author presents the interpretation of quantum mechanics in a simple and direct way. This book may be considered as a complement of specialized books whose aim is to present the mathematical developments of quantum mechanics. As early as the beginning of quantum theory, Bohr, Heisenberg and Pauli proposed the basis of what is today called the interpretation of Copenhagen. This interpretation is still valid but 2 important discoveries have led to renew some aspects of the interpretation of Copenhagen. The first one was the discovery of the decoherence phenomenon which is responsible for the absence of quantum interferences in the macroscopic world. The second discovery was the achievement of the complete derivation of classical physics from quantum physics, it means that the classical determinism fits in the framework of quantum probabilism. A short summary ends each chapter. (A.C.)

  14. Mechanical shock absorber

    International Nuclear Information System (INIS)

    Vrillon, Bernard.

    1973-01-01

    The mechanical shock absorber described is made of a constant thickness plate pierced with circular holes regularly distributed in such a manner that for all the directions along which the strain is applied during the shock, the same section of the substance forming the plate is achieved. The shock absorber is made in a metal standing up to extensive deformation before breaking, selected from a group comprising mild steels and austenitic stainless steels. This apparatus is used for handling pots of fast neutron reactor fuel elements [fr

  15. Introduction to continuum mechanics

    CERN Document Server

    Rubin, David; Lai, W Michael

    1994-01-01

    Continuum mechanics studies the response of materials to different loading conditions. The concept of tensors is introduced through the idea of linear transformation in a self-contained chapter, and the interrelation of direct notation, indicial notation and matrix operations is clearly presented. A wide range of idealized materials are considered through simple static and dynamic problems, and the book contains an abundance of illustrative examples and problems, many with solutions. Through the addition of more advanced material (solution of classical elasticity problems, constitutive e

  16. Fracture mechanics safety approaches

    International Nuclear Information System (INIS)

    Roos, E.; Schuler, X.; Eisele, U.

    2004-01-01

    Component integrity assessments require the knowledge of reliable fracture toughness parameters characterising the initiation of the failure process in the whole relevant temperature range. From a large number of fracture mechanics tests a statistically based procedure was derived allowing to quantify the initiation of fracture toughness as a function of temperature as a closed function as well as the temperature dependence of the cleavage instability parameters. Alternatively to the direct experimental determination one also can use a correlation between fracture toughness and notch impact energy. (orig.)

  17. Axiomation of quantum mechanics

    International Nuclear Information System (INIS)

    Kotecky, R.

    1975-01-01

    Deeper understanding of the basic structure of the formalism of the modern quantum theory (as has been established during its 50 years' stormy development) has been brought about by its axiomatization - by founding the formalism merely on experimentally directly accountable postulates without referring to historical development, without any a priori nonessential or empirically nonexplicable assumptions. A summary is given of the common formalism of quantum mechanics and its most significant axiomatizations. The assumptions are discussed under which respective axiomatically described abstract structures may be modelled by means of the common formalisn of quantum theory (established on the theory of Hilbert spaces). (author)

  18. Quantum mechanics

    International Nuclear Information System (INIS)

    Ghatak, A.K.; Lokanathan, S.

    1975-01-01

    This textbook on quantum mechanics is intended for students at the graduate and post-graduate level. A balanced account of theory and applications is presented. Emphasis is laid on making results plausible and methods to be followed in solving problems. The various chapters in the book are devoted to the following: (1) Wave particle duality and uncertainty principle (2) Wave packets and time-dependent Schroedinger equation (3) Simple solutions of Schroedinger equation (4) Vector spaces and linear operators : Dirac notation (5) Angular momentum and spin (6) Addition of angular momenta (7) Time independent perturbation theory (8) The variational method (9) The WKB approximation (10) Elementary theory of scattering (11) Time-dependent perturbation theory (12) Motion in a magnetic field (13) Interaction of radiation with matter and (14) Relativistic theory. (A.K.)

  19. Acoustic Mechanical Feedthroughs

    Science.gov (United States)

    Sherrit, Stewart; Walkemeyer, Phillip; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea

    2013-01-01

    Electromagnetic motors can have problems when operating in extreme environments. In addition, if one needs to do mechanical work outside a structure, electrical feedthroughs are required to transport the electric power to drive the motor. In this paper, we present designs for driving rotary and linear motors by pumping stress waves across a structure or barrier. We accomplish this by designing a piezoelectric actuator on one side of the structure and a resonance structure that is matched to the piezoelectric resonance of the actuator on the other side. Typically, piezoelectric motors can be designed with high torques and lower speeds without the need for gears. One can also use other actuation materials such as electrostrictive, or magnetostrictive materials in a benign environment and transmit the power in acoustic form as a stress wave and actuate mechanisms that are external to the benign environment. This technology removes the need to perforate a structure and allows work to be done directly on the other side of a structure without the use of electrical feedthroughs, which can weaken the structure, pipe, or vessel. Acoustic energy is pumped as a stress wave at a set frequency or range of frequencies to produce rotary or linear motion in a structure. This method of transferring useful mechanical work across solid barriers by pumping acoustic energy through a resonant structure features the ability to transfer work (rotary or linear motion) across pressure or thermal barriers, or in a sterile environment, without generating contaminants. Reflectors in the wall of barriers can be designed to enhance the efficiency of the energy/power transmission. The method features the ability to produce a bi-directional driving mechanism using higher-mode resonances. There are a variety of applications where the presence of a motor is complicated by thermal or chemical environments that would be hostile to the motor components and reduce life and, in some instances, not be

  20. Mechanisms in ancient Chinese books with illustrations

    CERN Document Server

    Hsiao, Kuo-Hung

    2014-01-01

    This book presents a unique approach for studying mechanisms and machines with drawings that were depicted unclearly in ancient Chinese books. The historical, cultural and technical backgrounds of the mechanisms are explained, and various mechanisms described and illustrated in ancient books are introduced. By utilizing the idea for the conceptual design of modern mechanisms, all feasible designs of ancient mechanisms with uncertain members and joints that meet the technical standards of the subjects’ time periods are synthesized systematically. Ancient Chinese crossbows (the original crossbow and repeating crossbows), textile mechanisms (silk-reeling mechanism, spinning mechanisms, and looms), and many other artisan's tool mechanisms are used as illustrated examples.  Such an approach provides a logical method for the reconstruction designs of ancient mechanisms with uncertain structures. It also provides an innovative direction for researchers to further identify the original structures of mechanisms...