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Sample records for bunsatsu bimolecular mechanism

  1. Report on result 1998. Research and development on fusion area. Part 3 (biomolecular mechanism and design); 1998 nendo seika hokokusho. Yugo ryoiki kenkyu kaihatsu daisan bunsatsu (bimolecular mechanism and design)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    An organism is a molecular mechanical system consisting of nucleic acid, peptide and protein having a self-forming and a self-repairing function. For the purpose of creating cells, tissues and molecular mechanism alternating these biological functions, their basic technology was developed. Concretely, studies were made on three-dimensional cellular structural module engineering and biomolecular mechanism and design. Studies on biological soft tissue resulted in success by giving atmospheric glow discharge treatment to the inner surface of a tubular PVC. An artificial vitreous body was created using PVA hydrogels. In addition, liver cells were successfully cultured for the first time in the world. Studies on biological hard tissue revealed that osteopontin plays a role of a trigger for the initial differentiation of the osteoblast cell. Further, a basic experiment was carried out on the initial response of the cartilage cell. In the research on the molecular mechanism, examination was made on the mechanism of a double-head molecular motor. Examination was also made on the adjustment of the hydrogenase LB film as an electricity/hydrogen energy conversion element and on the biomolecular mechanism and design. (NEDO)

  2. The mechanism of the NHC catalyzed aza-Morita-Baylis-Hillman reaction: insights into a new substrate-catalyzed bimolecular pathway.

    Science.gov (United States)

    Verma, Pritha; Verma, Pragya; Sunoj, Raghavan B

    2014-04-14

    The first mechanistic study on the NHC-catalyzed aza-MBH reaction between cyclopentenone and N-mesylbenzaldimine using density functional theory reveals that a bimolecular mechanism, involving two molecules of benzaldimine in the proton transfer, is energetically more preferred over the conventional direct proton transfer.

  3. The influence of the "cage effect" on the mechanism of reversible bimolecular multistage chemical reactions in solutions.

    Science.gov (United States)

    Doktorov, Alexander B

    2015-08-21

    Manifestations of the "cage effect" at the encounters of reactants are theoretically treated by the example of multistage reactions in liquid solutions including bimolecular exchange reactions as elementary stages. It is shown that consistent consideration of quasi-stationary kinetics of multistage reactions (possible only in the framework of the encounter theory) for reactions proceeding near reactants contact can be made on the basis of the concepts of a "cage complex." Though mathematically such a consideration is more complicated, it is more clear from the standpoint of chemical notions. It is established that the presence of the "cage effect" leads to some important effects not inherent in reactions in gases or those in solutions proceeding in the kinetic regime, such as the appearance of new transition channels of reactant transformation that cannot be caused by elementary event of chemical conversion for the given mechanism of reaction. This results in that, for example, rate constant values of multistage reaction defined by standard kinetic equations of formal chemical kinetics from experimentally measured kinetics can differ essentially from real values of these constants.

  4. Rotational effects in complex-forming bimolecular substitution reactions: A quantum-mechanical approach

    Science.gov (United States)

    Hennig, Carsten; Schmatz, Stefan

    2009-12-01

    The quantum dynamics of the complex-forming SN2 reaction Cl-+CH3Br→ClCH3+Br- is studied with emphasis on rotational effects. The pseudotriatomic system Cl-Me-Br is treated with a corresponding three-dimensional (3D) potential energy surface as a function of the two scattering coordinates and the enclosed angle where the geometry of the methyl group Me is optimized at each point. The 3D space is divided into three different parts, the interaction region, an intermediate region, and the asymptotic region. In line with simple classical-mechanical arguments and previous classical trajectory calculations, initial rotational motion of CH3Br seemingly decreases the reaction probability. However, the dynamical inclusion of the rotational degree of freedom and the presence of the many rovibrational product states overall lead to a large increase in reactivity compared to our previous collinear study on this reaction. If the reactant is rotationally excited, the higher vibrational product states are depleted in favor of lower-lying levels. Starting the reaction with rotationless reactants may end up in significant rotational excitation in the product molecules (translation-to-rotation energy transfer). On the other hand, initial rotational energy in rotationally highly excited reactants is to a large amount converted into translational and vibrational energy. The average amount of rotational energy in the products shows a twofold vibrational excitation-independent saturation (i.e., memorylessness), with respect to both initial rotational excitation and translational energy. Since only about one-half of all reactant states end in rotationless products, the reaction probability should be increased by a factor of 2; the actually larger reactivity points to other dynamical effects that play an important role in the reaction.

  5. The influence of the "cage" effect on the mechanism of reversible bimolecular multistage chemical reactions proceeding from different sites in solutions.

    Science.gov (United States)

    Doktorov, Alexander B

    2016-08-28

    Manifestations of the "cage" effect at the encounters of reactants have been theoretically treated on the example of multistage reactions (including bimolecular exchange reactions as elementary stages) proceeding from different active sites in liquid solutions. It is shown that for reactions occurring near the contact of reactants, consistent consideration of quasi-stationary kinetics of such multistage reactions (possible in the framework of the encounter theory only) can be made on the basis of chemical concepts of the "cage complex," just as in the case of one-site model described in the literature. Exactly as in the one-site model, the presence of the "cage" effect gives rise to new channels of reactant transformation that cannot result from elementary event of chemical conversion for the given reaction mechanism. Besides, the multisite model demonstrates new (as compared to one-site model) features of multistage reaction course.

  6. Bimolecular recombination in organic photovoltaics.

    Science.gov (United States)

    Lakhwani, Girish; Rao, Akshay; Friend, Richard H

    2014-01-01

    The recombination of electrons and holes is a major loss mechanism in photovoltaic devices that controls their performance. We review scientific literature on bimolecular recombination (BR) in bulk heterojunction organic photovoltaic devices to bring forward existing ideas on the origin and nature of BR and highlight both experimental and theoretical work done to quantify its extent. For these systems, Langevin theory fails to explain BR, and recombination dynamics turns out to be dependent on mobility, temperature, electric field, charge carrier concentration, and trapped charges. Relationships among the photocurrent, open-circuit voltage, fill factor, and morphology are discussed. Finally, we highlight the recent emergence of a molecular-level picture of recombination, taking into account the spin and delocalization of charges. Together with the macroscopic picture of recombination, these new insights allow for a comprehensive understanding of BR and provide design principles for future materials and devices.

  7. Studies on the Mechanism for the Bimolecular Metathesis Reaction CH3+HCl(←→)CH4+Cl

    Institute of Scientific and Technical Information of China (English)

    ZHOU,Zheng-Yu (周正宇); ZHOU,Zheng-Yu; CHEN,Guang(陈光); CHEN,Guang; ZHOU,Xin-Ming(周欣明); ZHOU,Xin-Ming; FU,Hui(傅惠); FU,Hui

    2001-01-01

    The geometry optimization of the transition state, the precursor complex and the successor complex was performed at the 6-311G* basis set level. From the analysis of the vibrational frequency of the precursor complex, transition state, successor complex and the isolated state, the reaction mechanism was derived which was complicated with the boni-rupture electron transfer theory. The atom H in molecule HCl attacks the atom C, forming a transition state via the precursor complex and the electron-transfer happens in precursor complex.Ami the active energy, electronic coupling matrix element,the reorganization energy, and the reaction rate are obtained.

  8. Phosphorelay of non-orthodox two component systems functions through a bi-molecular mechanism in vivo

    DEFF Research Database (Denmark)

    Jovanovic, Goran; Sheng, Xia; Ale, Angelique;

    2015-01-01

    the functional relevance of the dimerization of a non-orthodox or hybrid histidine kinase along which the phosphorelay takes place has been a subject of debate. We use a combination of molecular and genetic approaches, coupled to mathematical and statistical modelling, to demonstrate that the different possible...... intra- and inter-molecular mechanisms of phosphotransfer are formally non-identifiable in Escherichia coli expressing the ArcB non-orthodox histidine kinase used in anoxic redox control. In order to resolve this issue we further analyse the mathematical model in order to identify discriminatory...... in the histidine kinase. This is the first detailed mechanistic analysis of the molecular processes involved in non-orthodox two-component signalling and our results suggest strongly that dimerization facilitates more discriminatory proof-reading of external signals, via these allosteric reactions, prior to them...

  9. Stereoselective bimolecular phenoxyl radical coupling by an auxiliary (dirigent) protein without an active center

    Energy Technology Data Exchange (ETDEWEB)

    Davin, L.B.; Wang, Huai-Bin; Crowell, A.L. [Washington State Univ., Pullman, WA (United States)] [and others

    1997-01-17

    The regio- and stereospecificity of bimolecular phenoxy radical coupling reactions, of especial importance in lignin and lignan biosynthesis, are clearly controlled in some manner in vivo; yet in vitro coupling by oxidases, such as laccases, only produce racemic products. In other words, laccases, peroxidases, and comparable oxidases are unable to control regio- or stereospecificity by themselves and thus some other agent must exist. A 78-kilodalton protein has been isolated that, in the presence of an oxidase or one electron oxidant, effects stereoselective bimolecular phenoxy radical coupling in vitro. Itself lacking a catalytically active (oxidative) center, its mechanism of action is presumed to involve capture of E-coniferyl alcohol-derived free-radical intermediates, with consequent stereoselective coupling to give (+)-pinoresinol. 25 refs., 6 figs., 3 tabs.

  10. Photoinduced Bimolecular Electron Transfer from Cyano Anions in Ionic Liquids.

    Science.gov (United States)

    Wu, Boning; Liang, Min; Maroncelli, Mark; Castner, Edward W

    2015-11-19

    Ionic liquids with electron-donating anions are used to investigate rates and mechanisms of photoinduced bimolecular electron transfer to the photoexcited acceptor 9,10-dicyanoanthracene (9,10-DCNA). The set of five cyano anion ILs studied comprises the 1-ethyl-3-methylimidazolium cation paired with each of these five anions: selenocyanate, thiocyanate, dicyanamide, tricyanomethanide, and tetracyanoborate. Measurements with these anions dilute in acetonitrile and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide show that the selenocyanate and tricyanomethanide anions are strong quenchers of the 9,10-DCNA fluorescence, thiocyanate is a moderately strong quencher, dicyanamide is a weak quencher, and no quenching is observed for tetracyanoborate. Quenching rates are obtained from both time-resolved fluorescence transients and time-integrated spectra. Application of a Smoluchowski diffusion-and-reaction model showed that the complex kinetics observed can be fit using only two adjustable parameters, D and V0, where D is the relative diffusion coefficient between donor and acceptor and V0 is the value of the electronic coupling at donor-acceptor contact.

  11. Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

    Energy Technology Data Exchange (ETDEWEB)

    Bradforth, S.E.

    1992-11-01

    The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound {yields} bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN{sup {minus}}, NCO{sup {minus}} and NCS{sup {minus}}. Transition state photoelectron spectra are presented for the following systems Br + HI, Cl + HI, F + HI, F + CH{sub 3}0H,F + C{sub 2}H{sub 5}OH,F + OH and F + H{sub 2}. A time dependent framework for the simulation and interpretation of the bound {yields} free transition state photoelectron spectra is subsequently developed and applied to the hydrogen transfer reactions Br + HI, F + OH {yields} O({sup 3}P, {sup 1}D) + HF and F + H{sub 2}. The theoretical approach for the simulations is a fully quantum-mechanical wave packet propagation on a collinear model reaction potential surface. The connection between the wavepacket time evolution and the photoelectron spectrum is given by the time autocorrelation function. For the benchmark F + H{sub 2} system, comparisons with three-dimensional quantum calculations are made.

  12. Analysis of Brownian Dynamics Simulations of Reversible Bimolecular Reactions

    KAUST Repository

    Lipková, Jana

    2011-01-01

    A class of Brownian dynamics algorithms for stochastic reaction-diffusion models which include reversible bimolecular reactions is presented and analyzed. The method is a generalization of the λ-bcȳ model for irreversible bimolecular reactions which was introduced in [R. Erban and S. J. Chapman, Phys. Biol., 6(2009), 046001]. The formulae relating the experimentally measurable quantities (reaction rate constants and diffusion constants) with the algorithm parameters are derived. The probability of geminate recombination is also investigated. © 2011 Society for Industrial and Applied Mathematics.

  13. Universal model for exoergic bimolecular reactions and inelastic processes

    CERN Document Server

    Gao, Bo

    2010-01-01

    From a rigorous multichannel quantum-defect formulation of bimolecular processes, we derive a fully quantal and analytic model for the total rate of exoergic bimolecular reactions and/or inelastic processes that is applicable over a wide range of temperatures including the ultracold regime. The theory establishes a connection between the ultracold chemistry and the regular chemistry by showing that the same theory that gives the quantum threshold behavior agrees with the classical Gorin model at higher temperatures. In between, it predicts that the rates for identical bosonic molecules and distinguishable molecules would first decrease with temperature outside of the Wigner threshold region, before rising after a minimum is reached.

  14. On the possibility of negative activation energies in bimolecular reactions

    Science.gov (United States)

    Jaffe, R. L.

    1978-01-01

    The temperature dependence of the rate constants for model reacting systems was studied to understand some recent experimental measurements which imply the existence of negative activation energies. A collision theory model and classical trajectory calculations are used to demonstrate that the reaction probability can vary inversely with collision energy for bimolecular reactions occurring on attractive potential energy surfaces. However, this is not a sufficient condition to ensure that the rate constant has a negative temperature dependence. On the basis of these calculations, it seems unlikely that a true bimolecular reaction between neutral molecules will have a negative activation energy.

  15. RPMDrate: Bimolecular chemical reaction rates from ring polymer molecular dynamics

    KAUST Repository

    Suleimanov, Yu.V.

    2013-03-01

    We present RPMDrate, a computer program for the calculation of gas phase bimolecular reaction rate coefficients using the ring polymer molecular dynamics (RPMD) method. The RPMD rate coefficient is calculated using the Bennett-Chandler method as a product of a static (centroid density quantum transition state theory (QTST) rate) and a dynamic (ring polymer transmission coefficient) factor. The computational procedure is general and can be used to treat bimolecular polyatomic reactions of any complexity in their full dimensionality. The program has been tested for the H+H2, H+CH 4, OH+CH4 and H+C2H6 reactions. © 2012 Elsevier B.V. All rights reserved.

  16. Analysis of JP-10 Combustion Mechanism Based on Bimolecular Reaction Collision Model%气体介质中 JP-10液滴蒸发数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    袁嵩; 于亮; 赵汝岩

    2016-01-01

    为了进一步了解 JP-10燃料在航空发动机燃烧室中的蒸发燃烧机理,基于 SRK 状态方程,运用数学建模的方法,对 JP-10液滴蒸发过程进行了数值模拟并分析了环境因素对液滴蒸发表面温度变化及液滴生存时间变化的影响。研究表明,气体介质与液滴间的相对速度和环境压力及温度对 JP-10液滴蒸发湿球温度、升温过程及生存时间影响明显。%In order to further understand the evaporation and combustion mechanism of the JP-10 droplet in the engine combustion chamber,based on the SRK state equation,and by means of mathematical modeling,we simulated the evaporation process of the JP-10 droplet and analyzed the influences of environmental factors on the droplet surface temperature and life time.The results show that the influences of ambient pressure and temperature and relative velocity between gas and droplet on the JP-10 evaporation wet-bulb temperature,heating process and survival time are obvious.

  17. Tethered bimolecular lipid membranes - A novel model membrane platform

    Energy Technology Data Exchange (ETDEWEB)

    Knoll, Wolfgang; Koeper, Ingo; Naumann, Renate; Sinner, Eva-Kathrin [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)

    2008-10-01

    This contribution summarizes some of our efforts in designing, synthesizing, assembling, and characterizing functional tethered bimolecular lipid membranes (tBLMs) as a novel platform for biophysical studies of and with artificial membranes or for sensor development employing, e.g., membrane integral receptor proteins. Chemical coupling schemes based on thiol groups for Au substrates or silanes used in the case of oxide surfaces allow for the covalent and, hence, chemically and mechanically robust attachment of anchor lipids to the solid support, stabilizing the proximal layer of a tethered membrane on the transducer surface. Surface plasmon optics, the quartz crystal microbalance, fluorescence- and IR spectroscopies, and electrochemical techniques are used to characterize the build-up of these complex supramolecular interfacial architectures. We demonstrate, in particular, that bilayers with a specific electrical resistance of better than 10 M{omega} cm{sup 2} can be achieved routinely with this approach. The functionalization of the lipid membranes by the incorporation of peptides is demonstrated for the carrier valinomycin which shows in our tBLMs the expected discrimination by four orders of magnitude between the translocation of K{sup +}- and Na{sup +}-ions across the hydrophobic barrier. For the synthetic channel-forming peptide M2 the high electrical resistance of the bilayer with the correspondingly low background current allows for the recording of even single channel current fluctuations. From the many membrane proteins that we reconstituted so far we describe results obtained with the redox-protein cytochrome c oxidase. Here, we also use a genetically modified mutant with a His-tag at either the C- or the N-terminus for the oriented attachment of the protein via the NTA/Ni{sup 2+} approach. With this strategy, we not only can control the density of the immobilized functional units, we introduce a completely new and alternative concept for the

  18. Bimolecular recombination reactions: K-adiabatic and K-active forms of the bimolecular master equations and analytic solutions

    Science.gov (United States)

    Ghaderi, Nima

    2016-03-01

    Expressions for a K-adiabatic master equation for a bimolecular recombination rate constant krec are derived for a bimolecular reaction forming a complex with a single well or complexes with multiple well, where K is the component of the total angular momentum along the axis of least moment of inertia of the recombination product. The K-active master equation is also considered. The exact analytic solutions, i.e., the K-adiabatic and K-active steady-state population distribution function of reactive complexes, g(EJK) and g(EJ), respectively, are derived for the K-adiabatic and K-active master equation cases using properties of inhomogeneous integral equations (Fredholm type). The solutions accommodate arbitrary intermolecular energy transfer models, e.g., the single exponential, double exponential, Gaussian, step-ladder, and near-singularity models. At the high pressure limit, the krec for both the K-adiabatic and K-active master equations reduce, respectively, to the K-adiabatic and K-active bimolecular Rice-Ramsperger-Kassel-Marcus theory (high pressure limit expressions). Ozone and its formation from O + O2 are known to exhibit an adiabatic K. The ratio of the K-adiabatic to the K-active recombination rate constants for ozone formation at the high pressure limit is calculated to be ˜0.9 at 300 K. Results on the temperature and pressure dependence of the recombination rate constants and populations of O3 will be presented elsewhere.

  19. Bimolecular recombination reactions: K-adiabatic and K-active forms of the bimolecular master equations and analytic solutions.

    Science.gov (United States)

    Ghaderi, Nima

    2016-03-28

    Expressions for a K-adiabatic master equation for a bimolecular recombination rate constant krec are derived for a bimolecular reaction forming a complex with a single well or complexes with multiple well, where K is the component of the total angular momentum along the axis of least moment of inertia of the recombination product. The K-active master equation is also considered. The exact analytic solutions, i.e., the K-adiabatic and K-active steady-state population distribution function of reactive complexes, g(EJK) and g(EJ), respectively, are derived for the K-adiabatic and K-active master equation cases using properties of inhomogeneous integral equations (Fredholm type). The solutions accommodate arbitrary intermolecular energy transfer models, e.g., the single exponential, double exponential, Gaussian, step-ladder, and near-singularity models. At the high pressure limit, the krec for both the K-adiabatic and K-active master equations reduce, respectively, to the K-adiabatic and K-active bimolecular Rice-Ramsperger-Kassel-Marcus theory (high pressure limit expressions). Ozone and its formation from O + O2 are known to exhibit an adiabatic K. The ratio of the K-adiabatic to the K-active recombination rate constants for ozone formation at the high pressure limit is calculated to be ∼0.9 at 300 K. Results on the temperature and pressure dependence of the recombination rate constants and populations of O3 will be presented elsewhere.

  20. Understanding bimolecular machines: Theoretical and experimental approaches

    Science.gov (United States)

    Goler, Adam Scott

    This dissertation concerns the study of two classes of molecular machines from a physical perspective: enzymes and membrane proteins. Though the functions of these classes of proteins are different, they each represent important test-beds from which new understanding can be developed by the application of different techniques. HIV1 Reverse Transcriptase is an enzyme that performs multiple functions, including reverse transcription of RNA into an RNA/DNA duplex, RNA degradation by the RNaseH domain, and synthesis of dsDNA. These functions allow for the incorporation of the retroviral genes into the host genome. Its catalytic cycle requires repeated large-scale conformational changes fundamental to its mechanism. Motivated by experimental work, these motions were studied theoretically by the application of normal mode analysis. It was observed that the lowest order modes correlate with largest amplitude (low-frequency) motion, which are most likely to be catalytically relevant. Comparisons between normal modes obtained via an elastic network model to those calculated from the essential dynamics of a series of all-atom molecular dynamics simulations show the self-consistency between these calculations. That similar conformational motions are seen between independent theoretical methods reinforces the importance of large-scale subdomain motion for the biochemical action of DNA polymerases in general. Moreover, it was observed that the major subunits of HIV1 Reverse Transcriptase interact quasi-harmonically. The 5HT3A Serotonin receptor and P2X1 receptor, by contrast, are trans-membrane proteins that function as ligand gated ion channels. Such proteins feature a central pore, which allows for the transit of ions necessary for cellular function across a membrane. The pore is opened by the ligation of binding sites on the extracellular portion of different protein subunits. In an attempt to resolve the individual subunits of these membrane proteins beyond the diffraction

  1. Resonance Reaction in Diffusion-Influenced Bimolecular Reactions

    CERN Document Server

    Kolb, Jakob J; Dzubiella, Joachim

    2016-01-01

    We investigate the influence of a stochastically fluctuating step-barrier potential on bimolecular reaction rates by exact analytical theory and stochastic simulations. We demonstrate that the system exhibits a new resonant reaction behavior with rate enhancement if an appropriately defined fluctuation decay length is of the order of the system size. Importantly, we find that in the proximity of resonance the standard reciprocal additivity law for diffusion and surface reaction rates is violated due to the dynamical coupling of multiple kinetic processes. Together, these findings may have important repercussions on the correct interpretation of various kinetic reaction problems in complex systems, as, e.g., in biomolecular association or catalysis.

  2. Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

    Energy Technology Data Exchange (ETDEWEB)

    Bradforth, S.E.

    1992-11-01

    The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound [yields] bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN[sup [minus

  3. Force-activated reactivity switch in a bimolecular chemical reaction at the single molecule level

    Science.gov (United States)

    Szoszkiewicz, Robert; Garcia-Manyes, Sergi; Liang, Jian; Kuo, Tzu-Ling; Fernandez, Julio M.

    2010-03-01

    Mechanical force can deform the reacting molecules along a well-defined direction of the reaction coordinate. However, the effect of mechanical force on the free-energy surface that governs a chemical reaction is still largely unknown. The combination of protein engineering with single-molecule AFM force-clamp spectroscopy allows us to study the influence of mechanical force on the rate at which a protein disulfide bond is reduced by some reducing agents in a bimolecular substitution reaction (so-called SN2). We found that cleavage of a protein disulfide bond by hydroxide anions exhibits an abrupt reactivity ``switch'' at 500 pN, after which the accelerating effect of force on the rate of an SN2 chemical reaction greatly diminishes. We propose that an abrupt force-induced conformational change of the protein disulfide bond shifts its ground state, drastically changing its reactivity in SN2 chemical reactions. Our experiments directly demonstrate the action of a force-activated switch in the chemical reactivity of a single molecule. References: Sergi Garcia-Manyes, Jian Liang, Robert Szoszkiewicz, Tzu-Ling Kuo and Julio M. Fernandez, Nature Chemistry, 1, 236-242, 2009.

  4. Perspective: Vibrational-induced steric effects in bimolecular reactions

    Science.gov (United States)

    Liu, Kopin

    2015-02-01

    The concept of preferred collision geometry in a bimolecular reaction is at the heart of reaction dynamics. Exemplified by a series of crossed molecular beam studies on the reactions of a C-H stretch-excited CHD3(v1 = 1) with F, Cl, and O(3P) atoms, two types of steric control of chemical reactivity will be highlighted. A passive control is governed in a reaction with strong anisotropic entry valley that can significantly steer the incoming trajectories. This disorientation effect is illustrated by the F and O(3P) + CHD3(v1 = 1) reactions. In the former case, the long-range anisotropic interaction acts like an optical "negative" lens by deflecting the trajectories away from the favored transition-state geometry, and thus inhibiting the bond rupture of the stretch-excited CHD3. On the contrary, the interaction between O(3P) and CHD3(v1 = 1) behaves as a "positive" lens by funneling the large impact-parameter collisions into the cone of acceptance, and thereby enhances the reactivity. As for reactions with relatively weak anisotropic interactions in the entry valley, an active control can be performed by exploiting the polarization property of the infrared excitation laser to polarize the reactants in space, as demonstrated in the reaction of Cl with a pre-aligned CHD3(v1 = 1) reactant. A simpler case, the end-on versus side-on collisions, will be elucidated for demonstrating a means to disentangle the impact-parameter averaging. A few general remarks about some closely related issues, such as mode-, bond-selectivity, and Polanyi's rules, are made.

  5. Simulation study of the losses and influences of geminate and bimolecular recombination on the performances of bulk heterojunction organic solar cells

    Institute of Scientific and Technical Information of China (English)

    朱键卓; 祁令辉; 杜会静; 柴莺春

    2015-01-01

    We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fraction of electrons (holes) in the device are collected by anode (cathode). The direction of the corresponding current is opposite to the direction of photocurrent. And the current density increases with the bias increasing but decreases as bimolecular recombination (BR) or geminate recombination (GR) intensity increases. The maximum power, short circuit current, and fill factor display a stronger dependence on GR than on BR. While the influences of GR and BR on open circuit voltage are about the same. Our studies shed a new light on the loss mechanism and may provide a new way of improving the efficiency of bulk heterojunction organic solar cells.

  6. Charge-carrier relaxation dynamics in highly ordered poly( p -phenylene vinylene): Effects of carrier bimolecular recombination and trapping

    Science.gov (United States)

    Soci, Cesare; Moses, Daniel; Xu, Qing-Hua; Heeger, Alan J.

    2005-12-01

    We have studied the charge-carrier relaxation dynamics in highly ordered poly( p -phenylene vinylene) over a broad time range using fast (t>100ps) transient photoconductivity measurements. The carrier density was also monitored (t>100fs) by means of photoinduced absorption probed at the infrared active vibrational modes. We find that promptly upon charge-carrier photogeneration, the initial polaron dynamics is governed by bimolecular recombination, while later in the subnanosecond time regime carrier trapping gives rise to an exponential decay of the photocurrent. The more sensitive transient photocurrent measurements indicate that in the low excitation regime, when the density of photocarriers is comparable to that of the trapping states (˜1016cm-3) , carrier hopping between traps along with transport via extended states determines the carrier relaxation, a mechanism that is manifested by a long-lived photocurrent “tail.” This photocurrent tail is reduced by lowering the temperature and/or by increasing the excitation density. Based on these data, we develop a comprehensive kinetic model that takes into account the bipolar charge transport, the free-carrier bimolecular recombination, the carrier trapping, and the carrier recombination involving free and trapped carriers.

  7. Real-time observation of intersystem crossing induced by charge recombination during bimolecular electron transfer reactions

    KAUST Repository

    Alsam, Amani Abdu

    2016-09-21

    Real-time probing of intersystem crossing (ISC) and triplet-state formation after photoinduced electron transfer (ET) is a particularly challenging task that can be achieved by time-resolved spectroscopy with broadband capability. Here, we examine the mechanism of charge separation (CS), charge recombination (CR) and ISC of bimolecular photoinduced electron transfer (PET) between poly[(9,9-di(3,3′-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and dicyanobenzene (DCB) using time-resolved spectroscopy. PET from PFN to DCB is confirmed by monitoring the transient absorption (TA) and infrared spectroscopic signatures for the radical ion pair (DCB─•-PFN+•). In addition, our time-resolved results clearly demonstrate that CS takes place within picoseconds followed by CR within nanoseconds. The ns-TA data exhibit the clear spectroscopic signature of PFN triplet-triplet absorption, induced by the CR of the radical ion pairs (DCB─•-PFN+•). As a result, the triplet state of PFN (3PFN*) forms and subsequently, the ground singlet state is replenished within microseconds. © 2016

  8. Uncertainty for calculating transport on Titan: a probabilistic description of bimolecular diffusion parameters

    CERN Document Server

    Plessis, Sylvain; Mandt, Kathy; Greathouse, Thomas; Luspay-Kuti, Adrienn

    2015-01-01

    Bimolecular diffusion coefficients are important parameters used by atmospheric models to calculate altitude profiles of minor constituents in an atmosphere. Unfortunately, laboratory measurements of these coefficients were never conducted at temperature conditions relevant to the atmosphere of Titan. Here we conduct a detailed uncertainty analysis of the bimolecular diffusion coefficient parameters as applied to Titan's upper atmosphere to provide a better understanding of the impact of uncertainty for this parameter on models. Because temperature and pressure conditions are much lower than the laboratory conditions in which bimolecular diffusion parameters were measured, we apply a Bayesian framework, a problem-agnostic framework, to determine parameter estimates and associated uncertainties. We solve the Bayesian calibration problem using the open-source QUESO library which also performs a propagation of uncertainties in the calibrated parameters to temperature and pressure conditions observed in Titan's u...

  9. Pseudo-bimolecular [2+2] cycloaddition studied by time-resolved photoelectron spectroscopy

    DEFF Research Database (Denmark)

    Brogaard, Rasmus Y; Boguslavskiy, Andrey E; Schalk, Oliver

    2011-01-01

    The first study of pseudo-bimolecular cycloaddition reaction dynamics in the gas phase is presented. We used femtosecond time-resolved photoelectron spectroscopy (TRPES) to study the [2+2] photocycloaddition in the model system pseudo-gem-divinyl[2.2]paracyclophane. From X-ray crystal diffraction...

  10. Transcending the slow bimolecular recombination in lead-halide perovskites for electroluminescence

    Science.gov (United States)

    Xing, Guichuan; Wu, Bo; Wu, Xiangyang; Li, Mingjie; Du, Bin; Wei, Qi; Guo, Jia; Yeow, Edwin K. L.; Sum, Tze Chien; Huang, Wei

    2017-01-01

    The slow bimolecular recombination that drives three-dimensional lead-halide perovskites' outstanding photovoltaic performance is conversely a fundamental limitation for electroluminescence. Under electroluminescence working conditions with typical charge densities lower than 1015 cm−3, defect-states trapping in three-dimensional perovskites competes effectively with the bimolecular radiative recombination. Herein, we overcome this limitation using van-der-Waals-coupled Ruddlesden-Popper perovskite multi-quantum-wells. Injected charge carriers are rapidly localized from adjacent thin few layer (n≤4) multi-quantum-wells to the thick (n≥5) multi-quantum-wells with extremely high efficiency (over 85%) through quantum coupling. Light emission originates from excitonic recombination in the thick multi-quantum-wells at much higher decay rate and efficiency than bimolecular recombination in three-dimensional perovskites. These multi-quantum-wells retain the simple solution processability and high charge carrier mobility of two-dimensional lead-halide perovskites. Importantly, these Ruddlesden-Popper perovskites offer new functionalities unavailable in single phase constituents, permitting the transcendence of the slow bimolecular recombination bottleneck in lead-halide perovskites for efficient electroluminescence. PMID:28239146

  11. Transcending the slow bimolecular recombination in lead-halide perovskites for electroluminescence.

    Science.gov (United States)

    Xing, Guichuan; Wu, Bo; Wu, Xiangyang; Li, Mingjie; Du, Bin; Wei, Qi; Guo, Jia; Yeow, Edwin K L; Sum, Tze Chien; Huang, Wei

    2017-02-27

    The slow bimolecular recombination that drives three-dimensional lead-halide perovskites' outstanding photovoltaic performance is conversely a fundamental limitation for electroluminescence. Under electroluminescence working conditions with typical charge densities lower than 10(15) cm(-3), defect-states trapping in three-dimensional perovskites competes effectively with the bimolecular radiative recombination. Herein, we overcome this limitation using van-der-Waals-coupled Ruddlesden-Popper perovskite multi-quantum-wells. Injected charge carriers are rapidly localized from adjacent thin few layer (n≤4) multi-quantum-wells to the thick (n≥5) multi-quantum-wells with extremely high efficiency (over 85%) through quantum coupling. Light emission originates from excitonic recombination in the thick multi-quantum-wells at much higher decay rate and efficiency than bimolecular recombination in three-dimensional perovskites. These multi-quantum-wells retain the simple solution processability and high charge carrier mobility of two-dimensional lead-halide perovskites. Importantly, these Ruddlesden-Popper perovskites offer new functionalities unavailable in single phase constituents, permitting the transcendence of the slow bimolecular recombination bottleneck in lead-halide perovskites for efficient electroluminescence.

  12. Protein-protein interactions visualized by bimolecular fluorescence complementation in tobacco protoplasts and leaves.

    Science.gov (United States)

    Schweiger, Regina; Schwenkert, Serena

    2014-03-09

    Many proteins interact transiently with other proteins or are integrated into multi-protein complexes to perform their biological function. Bimolecular fluorescence complementation (BiFC) is an in vivo method to monitor such interactions in plant cells. In the presented protocol the investigated candidate proteins are fused to complementary halves of fluorescent proteins and the respective constructs are introduced into plant cells via agrobacterium-mediated transformation. Subsequently, the proteins are transiently expressed in tobacco leaves and the restored fluorescent signals can be detected with a confocal laser scanning microscope in the intact cells. This allows not only visualization of the interaction itself, but also the subcellular localization of the protein complexes can be determined. For this purpose, marker genes containing a fluorescent tag can be coexpressed along with the BiFC constructs, thus visualizing cellular structures such as the endoplasmic reticulum, mitochondria, the Golgi apparatus or the plasma membrane. The fluorescent signal can be monitored either directly in epidermal leaf cells or in single protoplasts, which can be easily isolated from the transformed tobacco leaves. BiFC is ideally suited to study protein-protein interactions in their natural surroundings within the living cell. However, it has to be considered that the expression has to be driven by strong promoters and that the interaction partners are modified due to fusion of the relatively large fluorescence tags, which might interfere with the interaction mechanism. Nevertheless, BiFC is an excellent complementary approach to other commonly applied methods investigating protein-protein interactions, such as coimmunoprecipitation, in vitro pull-down assays or yeast-two-hybrid experiments.

  13. Kinetics of carbon monoxide binding to phenobarbital-induced cytochrome P-450 from rat liver microsomes: a simple bimolecular process.

    Science.gov (United States)

    Oertle, M; Richter, C; Winterhalter, K H; Di Iorio, E E

    1985-01-01

    The kinetics of carbon monoxide binding to phenobarbital-induced cytochrome P-450 (P-450PB) and to its enzymatically inactive form P-420PB have been investigated by both stopped-flow and flash-photolysis spectrophotometry. When the simultaneous presence of both forms of the enzyme is taken into account, the binding of CO to these two proteins can be described in terms of two bimolecular processes with rate constants of 4.5 X 10(6) M-1.S-1 and 4.7 X 10(5) M-1.S-1 for P-450PB and 1.7 X 10(7) M-1.S-1 and 1.5 X 10(6) M-1.S-1 for P-420PB. From kinetic studies of the binding of CO to P-450PB under different experimental conditions, investigations of the homogeneity of our P-450PB preparations, and comparative kinetic investigations of P-450s from different sources, we conclude that CO binding to reduced P-450PB is a simple bimolecular process and that the observed biphasic traces are due to heterogeneity of the proteins. This conclusion is in contrast with previous reports of complex reaction mechanisms for the binding of CO to P-450PB. Optical spectroscopy studies indicate the existence of an equilibrium between P-450PB and P-420PB, at least for the reduced carbonyl derivatives of the enzymes. The interconversion is strongly influenced by the aggregation state of the protein. Large differences between the CO binding properties of P-450PB and those of P-420PB are found. These are discussed in terms of possible effects of the proximal ligation state of the iron on heme reactivity. PMID:3860832

  14. Use of X-ray diffraction, molecular simulations, and spectroscopy to determine the molecular packing in a polymer-fullerene bimolecular crystal

    KAUST Repository

    Miller, Nichole Cates

    2012-09-05

    The molecular packing in a polymer: fullerene bimolecular crystal is determined using X-ray diffraction (XRD), molecular mechanics (MM) and molecular dynamics (MD) simulations, 2D solid-state NMR spectroscopy, and IR absorption spectroscopy. The conformation of the electron-donating polymer is significantly disrupted by the incorporation of the electron-accepting fullerene molecules, which introduce twists and bends along the polymer backbone and 1D electron-conducting fullerene channels. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Use of X-ray diffraction, molecular simulations, and spectroscopy to determine the molecular packing in a polymer-fullerene bimolecular crystal

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Nichole Cates; Gysel, Roman; Sweetnam, Sean; McGehee, Michael D. [Department of Materials Science and Engineering, Stanford University, Stanford, CA (United States); Cho, Eunkyung [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Junk, Matthias J.N.; Chmelka, Bradley F. [Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA (United States); Risko, Chad; Kim, Dongwook; Bredas, Jean-Luc [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA (United States); Miller, Chad E. [Department of Materials Science and Engineering, Stanford University, Stanford, CA (United States); Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA (United States); Richter, Lee J.; Kline, R. Joseph [National Institute of Standards and Technology, Gaithersburg, MD (United States); Heeney, Martin; McCulloch, Iain [Department of Chemistry, Imperial College London (United Kingdom); Amassian, Aram [King Abdullah University of Science and Technology (KAUST), Physical Sciences and Engineering Division, Thuwal (Saudi Arabia); Acevedo-Feliz, Daniel; Knox, Christopher [King Abdullah University of Science and Technology (KAUST), Visualization Core Laboratory, Thuwal (Saudi Arabia); Hansen, Michael Ryan; Dudenko, Dmytro [Max Planck Institute for Polymer Research, Mainz (Germany); Toney, Michael F. [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA (United States)

    2012-11-27

    The molecular packing in a polymer: fullerene bimolecular crystal is determined using X-ray diffraction (XRD), molecular mechanics (MM) and molecular dynamics (MD) simulations, 2D solid-state NMR spectroscopy, and IR absorption spectroscopy. The conformation of the electron-donating polymer is significantly disrupted by the incorporation of the electron-accepting fullerene molecules, which introduce twists and bends along the polymer backbone and 1D electron-conducting fullerene channels. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Nanosecond pump and probe observation of bimolecular exciton effects in rubrene single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Kebra A.; Richman, Brittany R.; Biaggio, Ivan [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

    2015-06-01

    Transient grating pump and probe experiments are used to investigate excitonic processes on the nanosecond time scale in rubrene single crystals. We find that bimolecular interactions cause a photoinduced excited state density on the order of 0.5 × 10{sup 20 }cm{sup −3}—corresponding to an average distance of ∼3 nm between individual states—to decrease by a factor of 2 after 2 ns, following a typical power-law decay. We assign the observed power-law decays to high-density interactions between excited states. Because of the high efficiency singlet exciton fission observed in rubrene, these bimolecular interactions are likely those between triplet excitons or between coherent quantum superpositions of a singlet and a pair of triplet-excitons.

  17. Biofunctional hybrid materials: bimolecular organosilane monolayers on FeCr alloys

    Science.gov (United States)

    Vuori, Leena; Leppiniemi, Jenni; Hannula, Markku; Lahtonen, Kimmo; Hirsimäki, Mika; Nõmmiste, Ergo; Costelle, Leila; Hytönen, Vesa P.; Valden, Mika

    2014-10-01

    Hybrid organic-inorganic interfaces are the key to functionalization of stainless steel (SS). We present a solution-based deposition method for fabricating uniform bimolecular organosilane monolayers on SS and show that their properties and functionalities can be further developed through site-specific biotinylation. We correlate molecular properties of the interface with its reactivity via surface sensitive synchrotron radiation mediated high-resolution photoelectron spectroscopy (HR-PES) and chemical derivatization (CD), and we demonstrate specific bonding of streptavidin proteins to the hybrid interface. The method facilitates efficient growth of uniform bimolecular organosilane monolayers on SS under ambient conditions without the need to prime the SS surface with vacuum-deposited inorganic buffer layers. The obtained insights into molecular bonding, orientation, and behaviour of surface-confined organofunctional silanes on SS enable a new generic approach to functionalization of SS surfaces with versatile nanomolecular organosilane layers.

  18. Vectorially oriented monolayers of the cytochrome c/cytochrome oxidase bimolecular complex.

    OpenAIRE

    Edwards, A M; Blasie, J. K.; Bean, J. C.

    1998-01-01

    Vectorially oriented monolayers of yeast cytochrome c and its bimolecular complex with bovine heart cytochrome c oxidase have been formed by self-assembly from solution. Both quartz and Ge/Si multilayer substrates were chemical vapor deposited with an amine-terminated alkylsiloxane monolayer that was then reacted with a hetero-bifunctional cross-linking reagent, and the resulting maleimide endgroup surface then provided for covalent interactions with the naturally occurring single surface cys...

  19. Bimolecular crystals with an intercalated structure improve poly(p-phenylenevinylene)-based organic photovoltaic cells.

    Science.gov (United States)

    Lim, Kyung-Geun; Park, Jun-Mo; Mangold, Hannah; Laquai, Frédéric; Choi, Tae-Lim; Lee, Tae-Woo

    2015-01-01

    The exciton dissociation, recombination, and charge transport of bulk heterojunction organic photovoltaic cells (OPVs) is influenced strongly by the nanomorphology of the blend, such as the grain size and the molecular packing. Although it is well known that polymers based on amorphous poly(p-phenylenevinylene) (PPV) have a fundamental limit to their efficiency because of low carrier mobility, which leads to increased recombination and unbalanced charge extraction, herein, we demonstrate that the issue can be overcome by forming bimolecular crystals of an amorphous PPV-based polymer:phenyl-C61 -butyric acid methyl ester (PCBM) intercalated structure. We used amorphous poly(2,5-dioctyloxy-p-phenylene vinylene-alt-2',5'-thienylene vinylene) (PPVTV), which has a simple chemical structure. A reasonably high power conversion efficiency (∼3.5 %) was obtained, although the material has an intrinsically amorphous structure and a relatively large band gap (2.0 eV). We demonstrate a correlation between a well-ordered bimolecular crystal of PPVTV:PCBM and an improved hole mobility of a PPVTV:PCBM film compared to a pristine PPVTV film by using 2 D grazing incidence XRD and space-charge-limited current measurements. Furthermore, we show that the bimolecular crystal structure in high-performance OPVs is related to an optimum molecular packing, which is influenced by the PPVTV:PCBM blending ratio, side-chain length, and molecular weight of the PPVTV polymer. Improved charge transport in PPVTV:PCBM bimolecular crystals leads to a fast sweep out of charges and thus suppression of nongeminate recombination under the operating conditions.

  20. Ultrafast Photoinduced Electron Transfer in Bimolecular Donor-Acceptor Systems

    KAUST Repository

    Alsulami, Qana A.

    2016-11-30

    The efficiency of photoconversion systems, such as organic photovoltaic (OPV) cells, is largely controlled by a series of fundamental photophysical processes occurring at the interface before carrier collection. A profound understanding of ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) is the key determinant to improving the overall performances of photovoltaic devices. The discussion in this dissertation primarily focuses on the relevant parameters that are involved in photon absorption, exciton separation, carrier transport, carrier recombination and carrier collection in organic photovoltaic devices. A combination of steady-state and femtosecond broadband transient spectroscopies was used to investigate the photoinduced charge carrier dynamics in various donor-acceptor systems. Furthermore, this study was extended to investigate some important factors that influence charge transfer in donor-acceptor systems, such as the morphology, energy band alignment, electronic properties and chemical structure. Interestingly, clear correlations among the steady-state measurements, time-resolved spectroscopy results, grain alignment of the electron transporting layer (ETL), carrier mobility, and device performance are found. In this thesis, we explored the significant impacts of ultrafast charge separation and charge recombination at donor/acceptor (D/A) interfaces on the performance of a conjugated polymer PTB7-Th device with three fullerene acceptors: PC71BM, PC61BM and IC60BA. Time-resolved laser spectroscopy and high-resolution electron microscopy can illustrate the basis for fabricating solar cell devices with improved performances. In addition, we studied the effects of the incorporation of heavy metals into π-conjugated chromophores on electron transfer by monitoring the triplet state lifetime of the oligomer using transient absorption spectroscopy, as understanding the mechanisms controlling intersystem crossing and

  1. Simulation study of the losses and influences of geminate and bimolecular recombination on the performances of bulk heterojunction organic solar cells

    Science.gov (United States)

    Zhu, Jian-Zhuo; Qi, Ling-Hui; Du, Hui-Jing; Chai, Ying-Chun

    2015-10-01

    We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fraction of electrons (holes) in the device are collected by anode (cathode). The direction of the corresponding current is opposite to the direction of photocurrent. And the current density increases with the bias increasing but decreases as bimolecular recombination (BR) or geminate recombination (GR) intensity increases. The maximum power, short circuit current, and fill factor display a stronger dependence on GR than on BR. While the influences of GR and BR on open circuit voltage are about the same. Our studies shed a new light on the loss mechanism and may provide a new way of improving the efficiency of bulk heterojunction organic solar cells. Project supported by the Natural Science Foundation of Hebei Province, China (Grant No. A2012203016), the Science Fund from the Education Department of Hebei Province, China (Grant Nos. QN20131103 and Z2009114), the Doctor Foundation of Yanshan University, China (Grant No. B580), and the Young Teachers' Research Project of Yanshan University, China (Grant No. 13LGB028).

  2. Bimolecular Complementation to Visualize Filovirus VP40-Host Complexes in Live Mammalian Cells: Toward the Identification of Budding Inhibitors

    Directory of Open Access Journals (Sweden)

    Yuliang Liu

    2011-01-01

    Full Text Available Virus-host interactions play key roles in promoting efficient egress of many RNA viruses, including Ebola virus (EBOV or “e” and Marburg virus (MARV or “m”. Late- (L- domains conserved in viral matrix proteins recruit specific host proteins, such as Tsg101 and Nedd4, to facilitate the budding process. These interactions serve as attractive targets for the development of broad-spectrum budding inhibitors. A major gap still exists in our understanding of the mechanism of filovirus budding due to the difficulty in detecting virus-host complexes and mapping their trafficking patterns in the natural environment of the cell. To address this gap, we used a bimolecular complementation (BiMC approach to detect, localize, and follow the trafficking patterns of eVP40-Tsg101 complexes in live mammalian cells. In addition, we used the BiMC approach along with a VLP budding assay to test small molecule inhibitors identified by in silico screening for their ability to block eVP40 PTAP-mediated interactions with Tsg101 and subsequent budding of eVP40 VLPs. We demonstrated the potential broad spectrum activity of a lead candidate inhibitor by demonstrating its ability to block PTAP-dependent binding of HIV-1 Gag to Tsg101 and subsequent egress of HIV-1 Gag VLPs.

  3. Bimolecular reactions of activated species: An analysis of problematic HC(O)C(O) chemistry

    Science.gov (United States)

    Shannon, Robin J.; Robertson, Struan H.; Blitz, Mark A.; Seakins, Paul W.

    2016-09-01

    Experimental studies have demonstrated the importance of non-thermal bimolecular association chemistry. Recently a fully reversible method for incorporating any number of such non-thermal reactions into a single master equation has been developed (Green and Robertson, 2014) [10]. Using this methodology experimental results for the system: (1) (CHO)2 + OH → HC(O)C(O) + H2O, (2) HC(O)C(O) → HCO + CO, (3) HC(O)C(O) + O2 → OH + CO + CO2, are modeled, reproducing the temperature and pressure dependence of the OH yield. An issue remains as to how to model energy partition into HC(O)C(O).

  4. Theoretical Study of Electron Transfer in Bimolecular System of NH3 and H2O

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Mulliken, NPA, MK and CHelpG population analyses have been accomplished at the level of MP2/6-31G(d,p) for the title system. The variations of four kinds of charges on NH3 with intermolecular distance infer that electron transfers from NH3 to H2O. MK and CHelpG population analyses indicate more electron transfer than Mulliken and NPA ones. The atomic charges resulted from MK and CHelpG schemes infer that electron transfers from N in NH3 to H in H2O, which confirms that this bimolecular complex possesses linear structure as H3N…HOH.

  5. Transition state structure of arginine kinase: implications for catalysis of bimolecular reactions.

    Science.gov (United States)

    Zhou, G; Somasundaram, T; Blanc, E; Parthasarathy, G; Ellington, W R; Chapman, M S

    1998-07-21

    Arginine kinase belongs to the family of enzymes, including creatine kinase, that catalyze the buffering of ATP in cells with fluctuating energy requirements and that has been a paradigm for classical enzymological studies. The 1.86-A resolution structure of its transition-state analog complex, reported here, reveals its active site and offers direct evidence for the importance of precise substrate alignment in the catalysis of bimolecular reactions, in contrast to the unimolecular reactions studied previously. In the transition-state analog complex studied here, a nitrate mimics the planar gamma-phosphoryl during associative in-line transfer between ATP and arginine. The active site is unperturbed, and the reactants are not constrained covalently as in a bisubstrate complex, so it is possible to measure how precisely they are pre-aligned by the enzyme. Alignment is exquisite. Entropic effects may contribute to catalysis, but the lone-pair orbitals are also aligned close enough to their optimal trajectories for orbital steering to be a factor during nucleophilic attack. The structure suggests that polarization, strain toward the transition state, and acid-base catalysis also contribute, but, in contrast to unimolecular enzyme reactions, their role appears to be secondary to substrate alignment in this bimolecular reaction.

  6. Data preprocessing for parameter estimation. An application to a reactive bimolecular transport model

    CERN Document Server

    Cuch, Daniel A; Hasi, Claudio D El

    2015-01-01

    In this work we are concerned with the inverse problem of the estimation of modeling parameters for a reactive bimolecular transport based on experimental data that is non-uniformly distributed along the interval where the process takes place. We proposed a methodology that can help to determine the intervals where most of the data should be taken in order to obtain a good estimation of the parameters. For the purpose of reducing the cost of laboratory experiments, we propose to simulate data where is needed and it is not available, a PreProcesing Data Fitting (PPDF).We applied this strategy on the estimation of parameters for an advection-diffusion-reaction problem in a porous media. Each step is explained in detail and simulation results are shown and compared with previous ones.

  7. Benchmark Study on the Smallest Bimolecular Nucleophilic Substitution Reaction: H−+CH4 →CH4+H−

    Directory of Open Access Journals (Sweden)

    Marcel Swart

    2013-07-01

    Full Text Available We report here a benchmark study on the bimolecular nucleophilic substitution (SN2 reaction between hydride and methane, for which we have obtained reference energies at the coupled cluster toward full configuration-interaction limit (CC-cf/CBS. Several wavefunction (HF, MP2, coupled cluster and density functional methods are compared for their reliability regarding these reference data.

  8. Vibrational transitions in hydrogen bonded bimolecular complexes - A local mode perturbation theory approach to transition frequencies and intensities

    Science.gov (United States)

    Mackeprang, Kasper; Kjaergaard, Henrik G.

    2017-04-01

    The local mode perturbation theory (LMPT) model was developed to improve the description of hydrogen bonded XH-stretching transitions, where X is typically O or N. We present a modified version of the LMPT model to extend its application from hydrated bimolecular complexes to hydrogen bonded bimolecular complexes with donors such as alcohols, amines and acids. We have applied the modified model to a series of complexes of different hydrogen bond type and complex energy. We found that the differences between local mode (LM) and LMPT calculated fundamental XH-stretching transition wavenumbers and oscillator strengths were correlated with the strength of the hydrogen bond. Overall, we have found that the LMPT model in most cases predicts transition wavenumbers within 20 cm-1 of the experimental values.

  9. Bimolecular fluorescence complementation as a tool to study interactions of regulatory proteins in plant protoplasts.

    Science.gov (United States)

    Pattanaik, Sitakanta; Werkman, Joshua R; Yuan, Ling

    2011-01-01

    Protein-protein interactions are an important aspect of the gene regulation process. The expression of a gene in response to certain stimuli, within a specific cell type or at a particular developmental stage, involves a complex network of interactions between different regulatory proteins and the cis-regulatory elements present in the promoter of the gene. A number of methods have been developed to study protein-protein interactions in vitro and in vivo in plant cells, one of which is bimolecular fluorescence complementation (BiFC). BiFC is a relatively simple technique based upon the reconstitution of a fluorescent protein. The interacting protein complex can be visualized directly in a living plant cell when two non-fluorescent fragments, of an otherwise fluorescent protein, are fused to proteins found within that complex. Interaction of tagged proteins brings the two non-fluorescent fragments into close proximity and reconstitutes the fluorescent protein. In addition, the subcellular location of an interacting protein complex in the cell can be simultaneously determined. Using this approach, we have successfully demonstrated a protein-protein interaction between a R2R3 MYB and a basic helix-loop-helix MYC transcription factor related to flavonoid biosynthetic pathway in tobacco protoplasts.

  10. On the Temperature Dependence of the Rate Constant of the Bimolecular Reaction of two Hydrated Electrons

    Directory of Open Access Journals (Sweden)

    S.L. Butarbutar

    2013-08-01

    Full Text Available It has been a longstanding issue in the radiation chemistry of water that, even though H2 is a molecular product, its “escape” yield g(H2 increases with increasing temperature. A main source of H2 is the bimolecular reaction of two hydrated electrons (eaq. The temperature dependence of the rate constant of this reaction (k1, measured under alkaline conditions, reveals that the rate constant drops abruptly above ~150°C. Recently, it has been suggested that this temperature dependence should be regarded as being independent of pH and used in high-temperature modeling of near-neutral water radiolysis. However, when this drop in the eaq self-reaction rate constant is included in low (isolated spurs and high (cylindrical tracks linear energy transfer (LET modeling calculations, g(H2 shows a marked downward discontinuity at ~150°C which is not observed experimentally. The consequences of the presence of this discontinuity in g(H2 for both low and high LET radiation are briefly discussed in this communication. It is concluded that the applicability of the sudden drop in k1 observed at ~150°C in alkaline water to near-neutral water is questionable and that further measurements of the rate constant in pure water are highly desirable.

  11. An improved bimolecular fluorescence complementation tool based on superfolder green fluorescent protein

    Institute of Scientific and Technical Information of China (English)

    Jun Zhou; Jian Lin; Cuihong Zhou; Xiaoyan Deng; Bin Xia

    2011-01-01

    Bimolecular fluorescence complementation (BiFC) has been widely used in the analysis of protein-protein interactions (PPIs) in recent years. There are many notable advantages of BiFC such as convenience and direct visualization of PPI in cells. However, BiFC has one common limitation: the separated non-fluorescent fragments can be spontaneously self-assembled into an intact protein,which leads to false-positive results. In this study, a pair of complementary fragments (sfGFPN and sfGFPC) was constructed by splitting superfolder GFP (sfGFP) between the 214 and 215 amino acid residue, and sfGFPC was mutated by site-directed gene mutagenesis to decrease the signal of negative control. Our results showed that mutations in sfGFPC (sfGFPC(m12)) can effectively decrease the signal of negative control. Thus, we provide an improved BiFC tool for the analysis of PPI. Further,since the self-assembly problem is a common shortcoming for application of BiFC, our research provides a feasible strategy for other BiFC candidate proteins with the same problem.

  12. Visualization of protein interactions in living Drosophila embryos by the bimolecular fluorescence complementation assay

    Directory of Open Access Journals (Sweden)

    Merabet Samir

    2011-01-01

    Full Text Available Abstract Background Protein interactions control the regulatory networks underlying developmental processes. The understanding of developmental complexity will, therefore, require the characterization of protein interactions within their proper environment. The bimolecular fluorescence complementation (BiFC technology offers this possibility as it enables the direct visualization of protein interactions in living cells. However, its potential has rarely been applied in embryos of animal model organisms and was only performed under transient protein expression levels. Results Using a Hox protein partnership as a test case, we investigated the suitability of BiFC for the study of protein interactions in the living Drosophila embryo. Importantly, all BiFC parameters were established with constructs that were stably expressed under the control of endogenous promoters. Under these physiological conditions, we showed that BiFC is specific and sensitive enough to analyse dynamic protein interactions. We next used BiFC in a candidate interaction screen, which led to the identification of several Hox protein partners. Conclusion Our results establish the general suitability of BiFC for revealing and studying protein interactions in their physiological context during the rapid course of Drosophila embryonic development.

  13. [Hypothesis and application of bimolecular marking methods in Chinese materia medica].

    Science.gov (United States)

    Huang, Lu-qi; Qian, Dan; Deng, Chao

    2015-01-01

    Based on the current shortage of genuine/false authentication and quality evaluation in the molecular identification, and the weak functional gene research in the establishment of two-dimensional molecular markering methods for Chinese materia medica, the authors proposed a new method, the bimolecular marking methods (BIMM) for Chinese materia medica, combining DNA marker and metabolomics marker, that could simultaneously research the species and quality differences at the molecular level at the present stage. The authors introduced the concept, principle, methods, and technical process of BIMM, and summarized the technical advantages in this paper. Meanwhile, the application of BIMM in the identification of multiple sources of Chinese materia medica, years-identification, different locations, elite germplasm research, discovery of new drugs resources, protection of new varieties was also discussed. As a supplement of two-dimensional molecular markering method for Chinese materia medica, BIMM would not only expand connotation of identification of Chinese materia medica but also provide another effective way for quality evaluating.

  14. Bimolecular Excited-State Electron Transfer with Surprisingly Long-Lived Radical Ions

    KAUST Repository

    Alsam, Amani Abdu

    2015-09-02

    We explored the excited-state interactions of bimolecular, non-covalent systems consisting of cationic poly[(9,9-di(3,3’-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and 1,4-dicyanobenzene (DCB) using steady-state and time-resolved techniques, including femto- and nanosecond transient absorption and femtosecond infrared spectroscopies with broadband capabilities. The experimental results demonstrated that photo-induced electron transfer from PFN to DCB occurs on the picosecond time scale, leading to the formation of PFN+• and DCB-• radical ions. Interestingly, real-time observations of the vibrational marker modes on the acceptor side provided direct evidence and insight into the electron transfer process indirectly inferred from UV-Vis experiments. The band narrowing on the picosecond time scale observed on the antisymmetric C-N stretching vibration of the DCB radical anion provides clear experimental evidence that a substantial part of the excess energy is channeled into vibrational modes of the electron transfer product and that the geminate ion pairs dissociate. More importantly, our nanosecond time-resolved data indicate that the charge-separated state is very long lived ( 30 ns) due to the dissociation of the contact radical ion pair into free ions. Finally, the fast electron transfer and slow charge recombination anticipate the current donor−acceptor system with potential applications in organic solar cells.

  15. Visualization of molecular interactions using bimolecular fluorescence complementation analysis: characteristics of protein fragment complementation.

    Science.gov (United States)

    Kerppola, Tom K

    2009-10-01

    Investigations of the molecular processes that sustain life must include studies of these processes in their normal cellular environment. The bimolecular fluorescence complementation (BiFC) assay provides an approach for the visualization of protein interactions and modifications in living cells. This assay is based on the facilitated association of complementary fragments of a fluorescent protein that are fused to interaction partners. Complex formation by the interaction partners tethers the fluorescent protein fragments in proximity to each other, which can facilitate their association. The BiFC assay enables sensitive visualization of protein complexes with high spatial resolution. The temporal resolution of BiFC analysis is limited by the time required for fluorophore formation, as well as the stabilization of complexes by association of the fluorescent protein fragments. Many modifications and enhancements to the BiFC assay have been developed. The multicolor BiFC assay enables simultaneous visualization of multiple protein complexes in the same cell, and can be used to investigate competition among mutually exclusive interaction partners for complex formation in cells. The ubiquitin-mediated fluorescence complementation (UbFC) assay enables visualization of covalent ubiquitin family peptide conjugation to substrate proteins in cells. The BiFC assay can also be used to visualize protein binding to specific chromatin domains, as well as other molecular scaffolds in cells. BiFC analysis therefore provides a powerful approach for the visualization of a variety of processes that affect molecular proximity in living cells. The visualization of macromolecular interactions and modifications is of great importance owing to the central roles of proteins, nucleic acids and other macromolecular complexes in the regulation of cellular functions. This tutorial review describes the BiFC assay, and discusses the advantages and disadvantages of this experimental approach

  16. New GATEWAY vectors for High Throughput Analyses of Protein-Protein Interactions by Bimolecular Fluorescence Complementation

    Institute of Scientific and Technical Information of China (English)

    Christian Gehl; Rainer Waadt; J(o)rg Kudla; Ralf-R. Mendel; Robert Hansch

    2009-01-01

    Complex protein interaction networks constitute plant metabolic and signaling systems. Bimolecular fluores-cence complementation (BiFC) is a suitable technique to investigate the formation of protein complexes and the locali-zation of protein-protein interactions in planta. However, the generation of large plasmid collections to facilitate the exploration of complex interaction networks is often limited by the need for conventional cloning techniques. Here, we report the implementation of a GATEWAY vector system enabling large-scale combination and investigation of can-didate proteins in BiFC studies. We describe a set of 12 GATEWAY-compatible BiFC vectors that efficiently permit the com-bination of candidate protein pairs with every possible N-or C-terminal sub-fragment of S(CFP)3A or Venus, respectively, and enable the performance of multicolor BiFC (mcBiFC). We used proteins of the plant molybdenum metabolism, in that more than 20 potentially interacting proteins are assumed to form the cellular molybdenum network, as a case study to establish the functionality of the new vectors. Using these vectors, we report the formation of the molybdopterin synthase complex by interaction of Arabidopsis proteins Cnx6 and Cnx7 detected by BiFC as well as the simultaneous formation of Cn×6/Cn×6 and Cn×6/Cn×7 complexes revealed by mcBiFC. Consequently, these GATEWAY-based BiFC vector systems should significantly facilitate the large-scale investigation of complex regulatory networks in plant cells.

  17. Detection of protein-protein interactions in plants using bimolecular fluorescence complementation.

    Science.gov (United States)

    Bracha-Drori, Keren; Shichrur, Keren; Katz, Aviva; Oliva, Moran; Angelovici, Ruthie; Yalovsky, Shaul; Ohad, Nir

    2004-11-01

    Protein function is often mediated via formation of stable or transient complexes. Here we report the determination of protein-protein interactions in plants using bimolecular fluorescence complementation (BiFC). The yellow fluorescent protein (YFP) was split into two non-overlapping N-terminal (YN) and C-terminal (YC) fragments. Each fragment was cloned in-frame to a gene of interest, enabling expression of fusion proteins. To demonstrate the feasibility of BiFC in plants, two pairs of interacting proteins were utilized: (i) the alpha and beta subunits of the Arabidopsis protein farnesyltransferase (PFT), and (ii) the polycomb proteins, FERTILIZATION-INDEPENDENT ENDOSPERM (FIE) and MEDEA (MEA). Members of each protein pair were transiently co-expressed in leaf epidermal cells of Nicotiana benthamiana or Arabidopsis. Reconstitution of a fluorescing YFP chromophore occurred only when the inquest proteins interacted. No fluorescence was detected following co-expression of free non-fused YN and YC or non-interacting protein pairs. Yellow fluorescence was detected in the cytoplasm of cells that expressed PFT alpha and beta subunits, or in nuclei and cytoplasm of cells that expressed FIE and MEA. In vivo measurements of fluorescence spectra emitted from reconstituted YFPs were identical to that of a non-split YFP, confirming reconstitution of the chromophore. Expression of the inquest proteins was verified by immunoblot analysis using monoclonal antibodies directed against tags within the hybrid proteins. In addition, protein interactions were confirmed by immunoprecipitations. These results demonstrate that plant BiFC is a simple, reliable and relatively fast method for determining protein-protein interactions in plants.

  18. Experimental evidence of the relevance of orientational correlations in photoinduced bimolecular reactions in solution.

    Science.gov (United States)

    Angulo, Gonzalo; Cuetos, Alejandro; Rosspeintner, Arnulf; Vauthey, Eric

    2013-09-12

    A major problem in the extraction of the reaction probability in bimolecular processes is the disentanglement from the influence of molecular diffusion. One of the strategies to overcome it makes use of reactive solvents in which the reactants do not need to diffuse to encounter each other. However, most of our quantitative understanding of chemical reactions in solution between free partners is based on the assumption that they can be approximated by spheres because rotation averages their mutual orientations. This condition may not be fulfilled when the reaction takes place on time scales faster than that of molecular reorientation. In this work, the fluorescence quenching of two very similar polyaromatic hydrocarbons with different electric dipole moments is measured. The concentration of a liquid electron-donating quencher is varied from very dilute solutions to pure quencher solutions. In both cases, the thermodynamics of the reactions are very similar and, according to the Marcus expression, the kinetics are expected to proceed at similar rates. However, one of them is 10 times faster in the pure quencher solution. This difference starts at relatively low quencher concentrations. An explanation based on the fluorophore-solvent dipole-dipole interaction and the consequent orientational solvent structure is provided. The orientational correlation between fluorophore and quencher is calculated by means of computer simulations. Important differences depending on the fluorophore dipole moment are found. The kinetics can be explained quantitatively with a reaction-diffusion model that incorporates the effects of the presence of the dipole moment and the rotational diffusion, only in the highest quencher concentration case, but not in dilute solutions, most likely due to fundamental limitations of the kinetic theory.

  19. Modeling Bimolecular Reactions and Transport in Porous Media Via Particle Tracking

    Energy Technology Data Exchange (ETDEWEB)

    Dong Ding; David Benson; Amir Paster; Diogo Bolster

    2012-01-01

    We use a particle-tracking method to simulate several one-dimensional bimolecular reactive transport experiments. In this numerical method, the reactants are represented by particles: advection and dispersion dominate the flow, and molecular diffusion dictates, in large part, the reactions. The particle/particle reactions are determined by a combination of two probabilities dictated by the physics of transport and energetics of reaction. The first is that reactant particles occupy the same volume over a short time interval. The second is the conditional probability that two collocated particles favorably transform into a reaction. The first probability is a direct physical representation of the degree of mixing in an advancing displacement front, and as such lacks empirical parameters except for the user-defined number of particles. This number can be determined analytically from concentration autocovariance, if this type of data is available. The simulations compare favorably to two physical experiments. In one, the concentration of product, 1,2-naphthoquinoe-4-aminobenzene (NQAB) from reaction between 1,2-naphthoquinone-4-sulfonic acid (NQS) and aniline (AN), was measured at the outflow of a column filled with glass beads at different times. In the other, the concentration distribution of reactants (CuSO_4 and EDTA^{4-}) and products (CuEDTA^{4-}) were quantified by snapshots of transmitted light through a column packed with cryloite sand. The thermodynamic rate coefficient in the latter experiment was 10^7 times greater than the former experiment, making it essentially instantaneous. When compared to the solution of the advection-dispersion-reaction equation (ADRE) with the well-mixed reaction coefficient, the experiments and the particle-tracking simulations showed on the order of 20% to 40% less overall product, which is attributed to poor mixing. The poor mixing also leads to higher product concentrations on the edges of the mixing zones, which the particle

  20. Visualization and quantification of APP intracellular domain-mediated nuclear signaling by bimolecular fluorescence complementation.

    Directory of Open Access Journals (Sweden)

    Florian Riese

    Full Text Available BACKGROUND: The amyloid precursor protein (APP intracellular domain (AICD is released from full-length APP upon sequential cleavage by either α- or β-secretase followed by γ-secretase. Together with the adaptor protein Fe65 and the histone acetyltransferase Tip60, AICD forms nuclear multiprotein complexes (AFT complexes that function in transcriptional regulation. OBJECTIVE: To develop a medium-throughput machine-based assay for visualization and quantification of AFT complex formation in cultured cells. METHODS: We used cotransfection of bimolecular fluorescence complementation (BiFC fusion constructs of APP and Tip60 for analysis of subcellular localization by confocal microscopy and quantification by flow cytometry (FC. RESULTS: Our novel BiFC-constructs show a nuclear localization of AFT complexes that is identical to conventional fluorescence-tagged constructs. Production of the BiFC signal is dependent on the adaptor protein Fe65 resulting in fluorescence complementation only after Fe65-mediated nuclear translocation of AICD and interaction with Tip60. We applied the AFT-BiFC system to show that the Swedish APP familial Alzheimer's disease mutation increases AFT complex formation, consistent with the notion that AICD mediated nuclear signaling mainly occurs following APP processing through the amyloidogenic β-secretase pathway. Next, we studied the impact of posttranslational modifications of AICD on AFT complex formation. Mutation of tyrosine 682 in the YENPTY motif of AICD to phenylalanine prevents phosphorylation resulting in increased nuclear AFT-BiFC signals. This is consistent with the negative impact of tyrosine phosphorylation on Fe65 binding to AICD. Finally, we studied the effect of oxidative stress. Our data shows that oxidative stress, at a level that also causes cell death, leads to a reduction in AFT-BiFC signals. CONCLUSION: We established a new method for visualization and FC quantification of the interaction between

  1. Gas phase studies of the Pesci decarboxylation reaction: synthesis, structure, and unimolecular and bimolecular reactivity of organometallic ions.

    Science.gov (United States)

    O'Hair, Richard A J; Rijs, Nicole J

    2015-02-17

    promoting the formation of the organometallic ion. Where isomeric organometallic ions are generated and normal MS approaches cannot distinguish them, we describe approaches to elucidate the decarboxylation mechanism via determination of their structure. These "unmasked" organometallic ions, [RM(L)n](x), can also be structurally interrogated spectroscopically or via CID. We have thus compared the gas-phase structures and decomposition of several highly reactive and synthetically important organometallic ions for the first time. Perhaps the most significant aspect of this work is the study of bimolecular reactions, which provides experimental information on mechanistically obscure bond-formation and cross-coupling steps and the intrinsic reactivity of ions. We have sought to understand transformations of substrates including acid-base and hydrolysis reactions, along with reactions resulting in C-C bond formation. Our studies also allow a direct comparison of the performance of different metal catalysts in the individual elementary steps associated with protodecarboxylation and decarboxylative alkylation cycles. Electronic structure (DFT and ab initio) and dynamics (RRKM) calculations provide further mechanistic insights into these reactions. The broad implications of this research are that new reactions can be discovered and that the performance of metal catalysts can be evaluated in terms of each of their elementary steps. This has been particularly useful for the study of metal-mediated decarboxylation reactions.

  2. LET dependence of the response of EBT2 films in proton dosimetry modeled as a bimolecular chemical reaction

    Science.gov (United States)

    Perles, L. A.; Mirkovic, D.; Anand, A.; Titt, U.; Mohan, R.

    2013-12-01

    The dose response for films exposed to clinical x-ray beams is not linear and a calibration curve based on absorbed dose can be used to account for this effect. However for proton dosimetry the dose response of films exhibits an additional dependence because of the variation of the linear energy transfer (LET) as the protons penetrate matter. In the present study, we hypothesized that the dose response for EBT2 films can be mathematically described as a bimolecular chemical reaction. Furthermore, we have shown that the LET effect can be incorporated in the dose-response curve. A set of EBT2 films was exposed to pristine 161.6 MeV proton beams. The films were exposed to doses ranging from 0.93 to 14.82 Gy at a depth of 2 cm in water. The procedure was repeated with one film exposed to a lower energy beam (85.6 MeV). We also computed the LET and dose to water in the sensitive layer of the films with a validated Monte Carlo system, taking into account the film construction (polyester, adhesive and sensitive layers). The bimolecular model was able to accurately fit the experimental data with a correlation factor of 0.9998, and the LET correction factor was determined and incorporated into the dose-response function. We also concluded that the film orientation is important when determining the LET correction factor because of the asymmetric construction of the film.

  3. Why the apparent order of bimolecular recombination in blend organic solar cells can be larger than two: A topological consideration

    Science.gov (United States)

    Nenashev, A. V.; Wiemer, M.; Dvurechenskii, A. V.; Gebhard, F.; Koch, M.; Baranovskii, S. D.

    2016-07-01

    The apparent order δ of non-geminate recombination higher than δ = 2 has been evidenced in numerous experiments on organic bulk heterojunction (BHJ) structures intensively studied for photovoltaic applications. This feature is claimed puzzling, since the rate of the bimolecular recombination in organic BHJ systems is proportional to the product of the concentrations of recombining electrons and holes and therefore the reaction order δ = 2 is expected. In organic BHJ structures, electrons and holes are confined to two different material phases: electrons to the acceptor material (usually a fullerene derivative) while holes to the donor phase (usually a polymer). The non-geminate recombination of charge carriers can therefore happen only at the interfaces between the two phases. Considering a simple geometrical model of the BHJ system, we show that the apparent order of recombination can deviate from δ = 2 due solely to the topological structure of the system.

  4. Unusual charge transport and reduced bimolecular recombination in PDTSiTzTz:PC71BM bulk heterojunction blend

    Science.gov (United States)

    Slobodyan, O. V.; Danielson, E. L.; Moench, S. J.; Dinser, J. A.; Gutierrez, M.; Vanden Bout, D. A.; Holliday, B. J.; Dodabalapur, A.

    2015-06-01

    Solar cells with bulk heterojunction active layers containing donor-acceptor copolymer PDTSiTzTz exhibit persistent high fill factors with thicknesses up to 400 nm. Transport and recombination in a blend of PDTSiTzTz and fullerene derivative PC71BM is studied using lateral organic photovoltaic structures. This material system is characterized by carrier-concentration-dependent charge carrier mobilities, a strongly reduced bimolecular recombination factor, and a negative Poole-Frenkel coefficient. The analysis provides an explanation for the relatively thickness-independent fill factor behaviour seen in solar cells using the copolymer PDTSiTzTz. Cumulative insights from this copolymer can be employed for future organic photovoltaic material development, study of existing high performance bulk heterojunciton blends, and improved solar cell design.

  5. Molecular beam studies of unimolecular and bimolecular chemical reaction dynamics using VUV synchrotron radiation as a product probe

    Energy Technology Data Exchange (ETDEWEB)

    Blank, David Andrew [Univ. of California, Berkeley, CA (United States)

    1997-08-01

    This dissertation describes the use of a new molecular beam apparatus designed to use tunable VUV synchrotron radiation for photoionization of the products from scattering experiments. The apparatus was built at the recently constructed Advanced Light Source at Lawrence Berkeley National Laboratory, a third generation 1-2 GeV synchrotron radiation source. The new apparatus is applied to investigations of the dynamics of unimolecular reactions, photodissociation experiments, and bimolecular reactions, crossed molecular beam experiments. The first chapter describes the new apparatus and the VUV radiation used for photoionization. This is followed by a number of examples of the many advantages provided by using VUV photoionization in comparison with the traditional technique of electron bombardment ionization. At the end of the chapter there is a discussion of the data analysis employed in these scattering experiments. The remaining four chapters are complete investigations of the dynamics of four chemical systems using the new apparatus and provide numerous additional examples of the advantages provided by VUV photoionizaiton of the products. Chapters 2-4 are photofragment translational spectroscopy studies of the photodissociation dynamics of dimethyl sulfoxide, acrylonitrile, and vinyl chloride following absorption at 193 mn. All of these systems have multiple dissociation channels and provide good examples of the ability of the new apparatus to unravel the complex UV photodissociation dynamics that can arise in small polyatomic molecules.

  6. Comparative assessment of continuum-scale models of bimolecular reactive transport in porous media under pre-asymptotic conditions

    Science.gov (United States)

    Porta, G. M.; Ceriotti, G.; Thovert, J.-F.

    2016-02-01

    We compare the ability of various continuum-scale models to reproduce the key features of a transport setting associated with a bimolecular reaction taking place in the fluid phase and numerically simulated at the pore-scale level in a disordered porous medium. We start by considering a continuum-scale formulation which results from formal upscaling of this reactive transport process by means of volume averaging. The resulting (upscaled) continuum-scale system of equations includes nonlocal integro-differential terms and the effective parameters embedded in the model are quantified directly through computed pore-scale fluid velocity and pore space geometry attributes. The results obtained through this predictive model formulation are then compared against those provided by available effective continuum models which require calibration through parameter estimation. Our analysis considers two models recently proposed in the literature which are designed to embed incomplete mixing arising from the presence of fast reactions under advection-dominated transport conditions. We show that best estimates of the parameters of these two models heavily depend on the type of data employed for model calibration. Our upscaled nonlocal formulation enables us to reproduce most of the critical features observed through pore-scale simulation without any model calibration. As such, our results clearly show that embedding into a continuum-scale model the information content associated with pore-scale geometrical features and fluid velocity yields improved interpretation of typically available continuum-scale transport observations.

  7. Origin of the high open circuit voltage in planar heterojunction perovskite solar cells: Role of the reduced bimolecular recombination

    Science.gov (United States)

    Yang, Wenchao; Yao, Yao; Wu, Chang-Qin

    2015-03-01

    The high open circuit voltage is an attractive feature for the currently popular organic-inorganic hybrid perovskite solar cells. In this paper, by employing the macroscopic device model simulation, we investigate its origin for the planar heterojunction perovskite solar cells. Based on the calculated current density-voltage characteristics, it is revealed that compared to the excitonic solar cells, the fast thermal-activated exciton dissociation in the bulk due to the small exciton binding energy may improve the short circuit current and the fill factor, but its beneficial role on the open circuit voltage is marginal. The most significant contribution for the open circuit voltage comes from the reduced bimolecular recombination. In the perovskites, with the recombination prefactor many orders of magnitude smaller than that based on the Langevin's theory, the internal charge density level is significantly enhanced and the density gradient is removed, leading to the high quasi-Fermi level splitting and thus the small open circuit voltage loss. For the nonradiative recombination pathway due to the deep trap states, it may induce significant loss of open circuit voltage as the trap density is high, while for the moderately low density its effect on the open circuit voltage is small and negligible.

  8. In situ dimerization of multiple wild type and mutant zinc transporters in live cells using bimolecular fluorescence complementation.

    Science.gov (United States)

    Lasry, Inbal; Golan, Yarden; Berman, Bluma; Amram, Noy; Glaser, Fabian; Assaraf, Yehuda G

    2014-03-14

    Zinc transporters (ZnTs) facilitate zinc efflux and zinc compartmentalization, thereby playing a key role in multiple physiological processes and pathological disorders, presumed to be modulated by transporter dimerization. We recently proposed that ZnT2 homodimerization is the underlying basis for the dominant negative effect of a novel heterozygous G87R mutation identified in women producing zinc-deficient milk. To provide direct visual evidence for the in situ dimerization and function of multiple normal and mutant ZnTs, we applied here the bimolecular fluorescence complementation (BiFC) technique, which enables direct visualization of specific protein-protein interactions. BiFC is based upon reconstitution of an intact fluorescent protein including YFP when its two complementary, non-fluorescent N- and C-terminal fragments (termed YN and YC) are brought together by a pair of specifically interacting proteins. Homodimerization of ZnT1, -2, -3, -4, and -7 was revealed by high subcellular fluorescence observed upon co-transfection of non-fluorescent ZnT-YC and ZnT-YN; this homodimer fluorescence localized in the characteristic compartments of each ZnT. The validity of the BiFC assay in ZnT dimerization was further corroborated when high fluorescence was obtained upon co-transfection of ZnT5-YC and ZnT6-YN, which are known to form heterodimers. We further show that BiFC recapitulated the pathogenic role that ZnT mutations play in transient neonatal zinc deficiency. Zinquin, a fluorescent zinc probe applied along with BiFC, revealed the in situ functionality of ZnT dimers. Hence, the current BiFC-Zinquin technique provides the first in situ evidence for the dimerization and function of wild type and mutant ZnTs in live cells.

  9. Vectors for multi-color bimolecular fluorescence complementation to investigate protein-protein interactions in living plant cells

    Directory of Open Access Journals (Sweden)

    Kuang Lin-Yun

    2008-10-01

    Full Text Available Abstract Background The investigation of protein-protein interactions is important for characterizing protein function. Bimolecular fluorescence complementation (BiFC has recently gained interest as a relatively easy and inexpensive method to visualize protein-protein interactions in living cells. BiFC uses "split YFP" tags on proteins to detect interactions: If the tagged proteins interact, they may bring the two split fluorophore components together such that they can fold and reconstitute fluorescence. The sites of interaction can be monitored using epifluorescence or confocal microscopy. However, "conventional" BiFC can investigate interactions only between two proteins at a time. There are instances when one may wish to offer a particular "bait" protein to several "prey" proteins simultaneously. Preferential interaction of the bait protein with one of the prey proteins, or different sites of interaction between the bait protein and multiple prey proteins, may thus be observed. Results We have constructed a series of gene expression vectors, based upon the pSAT series of vectors, to facilitate the practice of multi-color BiFC. The bait protein is tagged with the C-terminal portion of CFP (cCFP, and prey proteins are tagged with the N-terminal portions of either Venus (nVenus or Cerulean (nCerulean. Interaction of cCFP-tagged proteins with nVenus-tagged proteins generates yellow fluorescence, whereas interaction of cCFP-tagged proteins with nCerulean-tagged proteins generates blue fluorescence. Additional expression of mCherry indicates transfected cells and sub-cellular structures. Using this system, we have determined in both tobacco BY-2 protoplasts and in onion epidermal cells that Agrobacterium VirE2 protein interacts with the Arabidopsis nuclear transport adapter protein importin α-1 in the cytoplasm, whereas interaction of VirE2 with a different importin α isoform, importin α-4, occurs predominantly in the nucleus. Conclusion Multi

  10. High temperature shock tube and theoretical studies on the thermal decomposition of dimethyl carbonate and its bimolecular reactions with H and D-atoms.

    Science.gov (United States)

    Peukert, S L; Sivaramakrishnan, R; Michael, J V

    2013-05-09

    The shock tube technique was used to study the high temperature thermal decomposition of dimethyl carbonate, CH3OC(O)OCH3 (DMC). The formation of H-atoms was measured behind reflected shock waves by using atomic resonance absorption spectrometry (ARAS). The experiments span a T-range of 1053-1157 K at pressures ∼0.5 atm. The H-atom profiles were simulated using a detailed chemical kinetic mechanism for DMC thermal decomposition. Simulations indicate that the formation of H-atoms is sensitive to the rate constants for the energetically lowest-lying bond fission channel, CH3OC(O)OCH3 → CH3 + CH3OC(O)O [A], where H-atoms form instantaneously at high temperatures from the sequence of radical β-scissions, CH3OC(O)O → CH3O + CO2 → H + CH2O + CO2. A master equation analysis was performed using CCSD(T)/cc-pv∞z//M06-2X/cc-pvtz energetics and molecular properties for all thermal decomposition processes in DMC. The theoretical predictions were found to be in good agreement with the present experimentally derived rate constants for the bond fission channel (A). The theoretically derived rate constants for this important bond-fission process in DMC can be represented by a modified Arrhenius expression at 0.5 atm over the T-range 1000-2000 K as, kA(T) = 6.85 × 10(98)T (-24.239) exp(-65250 K/T) s(-1). The H-atom temporal profiles at long times show only minor sensitivity to the abstraction reaction, H + CH3OC(O)OCH3 → H2 + CH3OC(O)OCH2 [B]. However, H + DMC is an important fuel destruction reaction at high temperatures. Consequently, measurements of D-atom profiles using D-ARAS allowed unambiguous rate constant measurements for the deuterated analog of reaction B, D + CH3OC(O)OCH3 → HD + CH3OC(O)OCH2 [C]. Reaction C is a surrogate for H + DMC since the theoretically predicted kinetic isotope effect at high temperatures (1000 - 2000K) is close to unity, kC ≈ 1.2 kB. TST calculations employing CCSD(T)/cc-pv∞z//M06-2X/cc-pvtz energetics and molecular properties

  11. Live cell imaging of interactions between replicase and capsid protein of Brome mosaic virus using Bimolecular Fluorescence Complementation: Implications for replication and genome packaging

    Energy Technology Data Exchange (ETDEWEB)

    Chaturvedi, Sonali; Rao, A.L.N., E-mail: arao@ucr.edu

    2014-09-15

    In Brome mosaic virus, it was hypothesized that a physical interaction between viral replicase and capsid protein (CP) is obligatory to confer genome packaging specificity. Here we tested this hypothesis by employing Bimolecular Fluorescent Complementation (BiFC) as a tool for evaluating protein–protein interactions in living cells. The efficacy of BiFC was validated by a known interaction between replicase protein 1a (p1a) and protein 2a (p2a) at the endoplasmic reticulum (ER) site of viral replication. Additionally, co-expression in planta of a bona fide pair of interacting protein partners of p1a and p2a had resulted in the assembly of a functional replicase. Subsequent BiFC assays in conjunction with mCherry labeled ER as a fluorescent cellular marker revealed that CP physically interacts with p2a, but not p1a, and this CP:p2a interaction occurs at the cytoplasmic phase of the ER. The significance of the CP:p2a interaction in BMV replication and genome packaging is discussed. - Highlights: • YFP fusion proteins of BMV p1a and p2a are biologically active. • Self-interaction was observed for p1a, p2a and CP. • CP interacts with p2a but not p1a. • Majority of reconstituted YFP resulting from bona fide fusion protein partners localized on ER.

  12. 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

  13. Theoretical Analysis on the Kinetic Isotope Effects of Bimolecular Nucleophilic Substitution (SN2 Reactions and Their Temperature Dependence

    Directory of Open Access Journals (Sweden)

    Wan-Chen Tsai

    2013-04-01

    Full Text Available Factors affecting the kinetic isotope effects (KIEs of the gas-phase SN2 reactions and their temperature dependence have been analyzed using the ion-molecule collision theory and the transition state theory (TST. The quantum-mechanical tunneling effects were also considered using the canonical variational theory with small curvature tunneling (CVT/SCT. We have benchmarked a few ab initio and density functional theory (DFT methods for their performance in predicting the deuterium KIEs against eleven experimental values. The results showed that the MP2/aug-cc-pVDZ method gave the most accurate prediction overall. The slight inverse deuterium KIEs usually observed for the gas-phase SN2 reactions at room temperature were due to the balance of the normal rotational contribution and the significant inverse vibrational contribution. Since the vibrational contribution is a sensitive function of temperature while the rotation contribution is temperature independent, the KIEs are thus also temperature dependent. For SN2 reactions with appreciable barrier heights, the tunneling effects were predicted to contribute significantly both to the rate constants and to the carbon-13, and carbon-14 KIEs, which suggested important carbon atom tunneling at and below room temperature.

  14. 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...

  15. Title: Elucidation of Environmental Fate of Artificial Sweeteners (Aspartame, Acesulfame K and Saccharin) by Determining Bimolecular Rate Constants with Hydroxyl Radical at Various pH and Temperature Conditions and Possible Reaction By-Products

    Science.gov (United States)

    Teraji, T.; Arakaki, T.; Suzuka, T.

    2012-12-01

    Use of artificial sweeteners in beverages and food has been rapidly increasing because of their non-calorie nature. In Japan, aspartame, acesulfame K and sucralose are among the most widely used artificial sweeteners. Because the artificial sweeteners are not metabolized in human bodies, they are directly excreted into the environment without chemical transformations. We initiated a study to better understand the fate of artificial sweeteners in the marine environment. The hydroxyl radical (OH), the most potent reactive oxygen species, reacts with various compounds and determines the environmental oxidation capacity and the life-time of many compounds. The steady-state OH concentration and the reaction rate constants between the compound and OH are used to estimate the life-time of the compound. In this study, we determine the bimolecular rate constants between aspartame, acefulfame K and saccharin and OH at various pH and temperature conditions using a competition kinetics technique. We use hydrogen peroxide as a photochemical source of OH. Bimolecular rate constant we obtained so far for aspartame was (2.6±1.2)×109 M-1 s-1 at pH = 3.0 and (4.9±2.3)×109 M-1 s-1 at pH = 5.5. Little effect was seen by changing the temperatures between 15 and 40 oC. Activation energy (Ea) was calculated to be -1.0 kJ mol-1 at pH = 3.0, +8.5 kJ mol-1 at pH = 5.5, which could be regarded as zero. We will report bimolecular rate constants at different pHs and temperatures for acesulfame K and saccharin, as well. Possible reaction by-products for aspartame will be also reported. We will further discuss the fate of aspartame in the coastal environment.

  16. Prevalence of Bimolecular Routes in the Activation of Diatomic Molecules with Strong Chemical Bonds (O2, NO, CO, N2) on Catalytic Surfaces.

    Science.gov (United States)

    Hibbitts, David; Iglesia, Enrique

    2015-05-19

    sites that are scarce on such surfaces. N-O bonds cleave instead via H*-assistance to form *HNOH* intermediates, with barriers much lower than for direct NO* dissociation. CO hydrogenation on Co and Ru occurs on crowded surfaces saturated with CO*; rates increase with increasing Co and Ru cluster size, indicating that low-index surfaces on large clusters can activate CO*. Direct CO*dissociation, however, occurs with high activation barriers on low-index Co and Ru surfaces, and even on defect sites (step-edge, corner sites) at high CO* coverages. CO* dissociation proceeds instead with H*-assistance to form *HCOH* species that cleave C-O bonds with lower barriers than direct CO* dissociation, irrespective of surface coordination. H2O increases CO activation rates by assisting H-additions to form *HCOH*, as in the case of peroxide formation in Au-catalyzed oxidations. N2 dissociation steps in NH3 synthesis on Ru and Fe are thought to also require defect sites; yet, barriers on Ru(0001) indicate that H*-assisted N2 activation - unlike O2, CO, and NO - is not significantly more facile than direct N2 dissociation, suggesting that defects and low-index planes may both contribute to NH3 synthesis rates. The activation of strong chemical bonds often occurs via bimolecular reactions. These steps weaken such bonds before cleavage on crowded low-index surfaces, thus avoiding the ubiquitous kinetic hurdles of direct dissociations without requiring defect sites.

  17. Thermal stabilities and decomposition mechanism of amino- and hydroxyl-functionalized ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhimin; Zhang, Yuwei [Department of Chemistry, Renmin University of China, Beijing 100872 (China); Zhou, Xiao-qin [College of Chemistry, Qufu Normal University, Shandong, Qufu 273165 (China); Cao, Yuanyuan [Department of Chemistry, Renmin University of China, Beijing 100872 (China); Mu, Tiancheng, E-mail: tcmu@chem.ruc.edu.cn [Department of Chemistry, Renmin University of China, Beijing 100872 (China)

    2014-02-01

    Highlights: • The long term thermal stabilities of [C{sub 2}NH{sub 2}MIM][Br] and [C{sub 3}OHMIM][Cl] are overestimated. • The thermal decomposition mechanisms of [C{sub 2}NH{sub 2}MIM][Br] and [C{sub 3}OHMIM][Cl] are complicated. • Bimolecular nucleophilic substitution (SN2) is the main reaction mechanism. - Abstract: Thermal stabilities and thermal decomposition mechanisms of amino-functionalized ionic liquid (IL) 1-aminoethyl-3-methylimidazolium bromide ([C{sub 2}NH{sub 2}MIM][Br]) and hydroxyl-functionalized IL 1-hydropropyl-3-methylimidazolium chloride ([C{sub 3}OHMIM][Cl]) were investigated by thermogravimetric analysis (TGA), TG–mass spectroscopy (TG–MS), density functional theory (DFT), and nuclear magnetic resonance (NMR) spectrum. Results show that the [C{sub 2}NH{sub 2}MIM][Br] and [C{sub 3}OHMIM][Cl] are stable up to 200 °C and 220 °C, respectively. Also, DFT calculation indicates that the thermal decomposition mechanisms of [C{sub 2}NH{sub 2}MIM][Br] and [C{sub 3}OHMIM][Cl] are complicated, while bimolecular nucleophilic substitution (SN2) is the main reaction mechanism. TG–MS and NMR spectra further prove the mechanisms.

  18. New Gateway-compatible vectors for a high-throughput protein-protein interaction analysis by a bimolecular fluorescence complementation (BiFC) assay in plants and their application to a plant clathrin structure analysis.

    Science.gov (United States)

    Nishimura, Kohji; Ishikawa, Syouta; Matsunami, Erika; Yamauchi, Junji; Homma, Keiichi; Faulkner, Christine; Oparka, Karl; Jisaka, Mitsuo; Nagaya, Tsutomu; Yokota, Kazushige; Nakagawa, Tsuyoshi

    2015-01-01

    Protein-protein interactions (PPI) play key roles in various biological processes. The bimolecular fluorescence complementation (BiFC) assay is an excellent tool for routine PPI analyses in living cells. We developed new Gateway vectors for a high-throughput BiFC analysis of plants, adopting a monomeric Venus split just after the tenth β-strand, and analyzed the interaction between Arabidopsis thaliana coated vesicle coatmers, the clathrin heavy chain (CHC), and the clathrin light chain (CLC). In competitive BiFC tests, CLC interacted with CHC through a coiled-coil motif in the middle section of CLC. R1340, R1448, and K1512 in CHC and W94 in CLC are potentially key amino acids underlying the inter-chain interaction, consistent with analyses based on homology modeling. Our Gateway BiFC system, the V10-BiFC system, provides a useful tool for a PPI analysis in living plant cells. The CLC-CHC interaction identified may facilitate clathrin triskelion assembly needed for cage formation.

  19. Theoretical Study on the Reaction Mechanism of F2+2HBr=2HF+Br2

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The gas phase reaction mechanism of F2 + 2HBr = 2HF + Br2 has been investigated by (U)MP2 at 6-311G** level, and a series of four-center and three-center transition states have been obtained. The reaction mechanism was achieved by comparing the activation energy of seven reaction paths, i.e. the dissociation energy of F2 is less than the activation energy of the bimolecular elementary reaction F2 + HBr → HF + BrF. Thus it is theoretically proved that the title reaction occurs more easily inthe free radical reaction with three medium steps.

  20. A multilayered representation, quantum mechanical and molecular mechanics study of the CH3 F + OH(-) reaction in water.

    Science.gov (United States)

    Chen, Jie; Xu, Yulong; Wang, Dunyou

    2014-03-05

    The bimolecular nucleophilic substitution (SN 2) reaction of CH3 F + OH(-) in aqueous solution was investigated using a combined quantum mechanical and molecular mechanics approach. Reactant complex, transition state, and product complex along the reaction pathway were analyzed in water. The potentials of mean force were calculated using a multilayered representation with the DFT and CCSD(T) level of theory for the reactive region. The obtained free energy activation barrier for this reaction at the CCSD(T)/MM representation is 18.3 kcal/mol which agrees well with the experimental value at ∼21.6 kcal/mol. Both the solvation effect and solute polarization effect play key roles on raising the activation barrier height in aqueous solution, with the former raising the barrier height by 3.1 kcal/mol, the latter 1.5 kcal/mol.

  1. Bimolecular reaction of CH{sub 3} + CO in solid p-H{sub 2}: Infrared absorption of acetyl radical (CH{sub 3}CO) and CH{sub 3}-CO complex

    Energy Technology Data Exchange (ETDEWEB)

    Das, Prasanta [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Lee, Yuan-Pern, E-mail: yplee@mail.nctu.edu.tw [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China)

    2014-06-28

    complex was observed instead. This rapid quenching poses a limitation in production of free radicals via bimolecular reactions in p-H{sub 2}.

  2. Theoretical and Experimental Studies on the Reaction Mechanism of Cl2+I2=2ICl

    Institute of Scientific and Technical Information of China (English)

    YANG Guo-Ying; YUAN Li-Xia; SUN De-Sheng; WANG Zun-Yao; JIANG Tao

    2006-01-01

    The gas phase reaction mechanism of Cl2 + I2 = 2ICI has been theoretically investigated by DFT method at the B3LYP/3-21G* level. Transition states of three reaction channels were consequently given. The results indicate that in the title reaction the least activation energy of bi-molecular reaction was smaller than the dissociation energies of I2 and Cl2, and thus the reaction mechanism was the course of molecule-molecule interaction at low reaction rate. If other factors such as illumination were taken into account, I2 could dissociate into I atoms and then react with Cl2,or Cl2 dissociates into Cl atoms and reacts with I2. These were photochemical reactions with high reaction speed. The theoretical results were further validated with absorbance measurement at 516 nm.

  3. Investigation on the mechanism and applications of the reaction Cl2+2HBr=2HCl+Br2

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The mechanism of reaction Cl2+2HBr=2HCl+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-cen- tred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, re-spectively) of two bimolecular elementary reactions Cl2+HBr→HCl+BrCl and BrCl+HBr→HCl+Br2 is smaller than the dissociation energy of Cl2, HBr and BrCl, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engi-neering process of recycling Br2 from HBr. Gaseous Cl2 directly reacts with HBr gas, which pro-duces gaseous mixtures containing Br2, and liquid Br2 and HCl are obtained by cooling the mixtures and further separated by absorption with CCl4. The recovery percentage of Br2 is more than 96%, and the Cl2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.

  4. Investigation on the mechanism and applications of the reaction Cl2+2HBr=2HCl+Br2

    Institute of Scientific and Technical Information of China (English)

    肖鹤鸣; 王遵尧; 肖继军; 陈兆旭

    2001-01-01

    The mechanism of reaction CI2+2HBr=2HCI+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-centred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, respectively) of two bimolecular elementary reactions CI2+HBr→HCI+BrCI and BrCI+HBr→HCI+Br2 is smaller than the dissociation energy of CI2, HBr and BrCI, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engineering process of recycling Br2 from HBr. Gaseous CI2 directly reacts with HBr gas, which produces gaseous mixtures containing Br2, and liquid Br2 and HCI are obtained by cooling the mixtures and further separated by absorption with CCI4. The recovery percentage of Br2 is more than 96%, and the CI2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.

  5. N-β-羟乙基乙二胺在铜催化剂上的反应机理%REACTION MECHANISM OF N-β-HYDROXYETHYLETHYLENEDIAMINE ON COPPER CONTAINING CATALYST

    Institute of Scientific and Technical Information of China (English)

    孟祎; 许正双; 陈立功; 王多禄; 冯亚青

    2001-01-01

    The mechanism of the reaction of N-β-dydroxyethylethylenediamine(HEDA) on copper under catalysis for the synthesis of piperazine was studied.The structures of reaction mixtures were identified by GC-MS.The preliminary study demonstrats that the above reaction is an intermolecular catalytic amination of alcohol and was proved to proceed through dehydrogenation and hydrogenation.Under the reaction conditions HEDA may undertake the bimolecular disproportionation reaction.Furthermore,the similar nucleophilic substitution reactions between starting material and products,between products and products,possibly occur to give the corresponding byproducts.

  6. New methods for quantum mechanical reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, W.H. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States)

    1996-12-01

    Quantum mechanical methods are developed to describe the dynamics of bimolecular chemical reactions. We focus on developing approaches for directly calculating the desired quantity of interest. Methods for the calculation of single matrix elements of the scattering matrix (S-matrix) and initial state-selected reaction probabilities are presented. This is accomplished by the use of absorbing boundary conditions (ABC) to obtain a localized (L{sup 2}) representation of the outgoing wave scattering Green`s function. This approach enables the efficient calculation of only a single column of the S-matrix with a proportionate savings in effort over the calculation of the entire S-matrix. Applying this method to the calculation of the initial (or final) state-selected reaction probability, a more averaged quantity, requires even less effort than the state-to-state S-matrix elements. It is shown how the same representation of the Green`s function can be effectively applied to the calculation of negative ion photodetachment intensities. Photodetachment spectroscopy of the anion ABC{sup -} can be a very useful method for obtaining detailed information about the neutral ABC potential energy surface, particularly if the ABC{sup -} geometry is similar to the transition state of the neutral ABC. Total and arrangement-selected photodetachment spectra are calculated for the H{sub 3}O{sup -} system, providing information about the potential energy surface for the OH + H{sub 2} reaction when compared with experimental results. Finally, we present methods for the direct calculation of the thermal rate constant from the flux-position and flux-flux correlation functions. The spirit of transition state theory is invoked by concentrating on the short time dynamics in the area around the transition state that determine reactivity. These methods are made efficient by evaluating the required quantum mechanical trace in the basis of eigenstates of the Boltzmannized flux operator.

  7. Mechanism of alternating copolymerization of methyl methacrylate with styrene in the presence of diethylaluminum chloride

    Energy Technology Data Exchange (ETDEWEB)

    Zubov, V.P.; Lachinov, M.B.; Ignatova, E.V.; Georgiev, G.S.; Golubev, V.B.; Kabanov, V.A.

    1982-03-01

    A kinetic study of the propagation mechanism of the alternating copolymerization of styrene (St) with methyl methacrylate (MMA) in the presence of a complexing agent (diethylaluminum chloride, DEAC) in bulk and in tetrachloroethylene solutions at a molar ratio DEAC/MMA = 0.5 has been carried out. It has been shown that the copolymerization is a chain radical process characterized by a short active-center lifetime, bimolecular termination, and high rate of chain transfer to the complexed MMA. A kinetic scheme has been proposed for the propagation mechanism of alternating copolymerization in the presence of a complexing agent not requiring independent measurements of the equilibrium constant of complexation. It has been found that spontaneous and uv-initiated copolymerizations in the system have different mechanisms of initiation and a common mechanism of propagation. The propagation proceeds by addition of single monomers as well as donor-acceptor complexes of the comonomers to the propagation radicals, with the first mechanism being predominant. Inclusion of the monomers in the complex leads to an increase of the St reactivity and to a decrease of the MMA reactivity in propagation to the corresponding macroradicals in comparison with the reactivity of the free monomers. A number of kinetic and statistical parameters of the propagation reaction have been calculated.

  8. A new, double-inversion mechanism of the F(-) + CH3Cl SN2 reaction in aqueous solution.

    Science.gov (United States)

    Liu, Peng; Wang, Dunyou; Xu, Yulong

    2016-11-23

    Atomic-level, bimolecular nucleophilic substitution reaction mechanisms have been studied mostly in the gas phase, but the gas-phase results cannot be expected to reliably describe condensed-phase chemistry. As a novel, double-inversion mechanism has just been found for the F(-) + CH3Cl SN2 reaction in the gas phase [Nat. Commun., 2015, 6, 5972], here, using multi-level quantum mechanics methods combined with the molecular mechanics method, we discovered a new, double-inversion mechanism for this reaction in aqueous solution. However, the structures of the stationary points along the reaction path show significant differences from those in the gas phase due to the strong influence of solvent and solute interactions, especially due to the hydrogen bonds formed between the solute and the solvent. More importantly, the relationship between the two double-inversion transition states is not clear in the gas phase, but, here we revealed a novel intermediate complex serving as a "connecting link" between the two transition states of the abstraction-induced inversion and the Walden-inversion mechanisms. A detailed reaction path was constructed to show the atomic-level evolution of this novel double reaction mechanism in aqueous solution. The potentials of mean force were calculated and the obtained Walden-inversion barrier height agrees well with the available experimental value.

  9. 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…

  10. 苯甲酸铜固化环氧树脂的机理研究%Study on Curing Mechanism of Lead Benzoxy for Epoxy Resin

    Institute of Scientific and Technical Information of China (English)

    陈兴娟

    2001-01-01

    采用苯甲酸铅做固化剂,通过对环氧树脂固化物的红外光谱及DSC曲线分析,认为苯甲酸铅是一种催化型固化剂。它与环氧树脂混合后首先形成过渡状态,然后按双分子亲核取代(SN2)机理进行开环反应。%Using lead benzoxy as curing agent,cured epoxy resin was analyzed by means of IR spectrum and DSC curves.Lead benzoxy was considered to be catalytic curing agent.After it was mixed with epoxy resin,transition state was formed first.Then they got on with opening ring reactions according to bimolecular nucleophilic substitution mechanism(SN2).

  11. Elucidation of Environmental Fate of Artificial Sweetener, Aspartame by Determining Bimolecular Rate Constants with Hydroxyl Radical at Various pH and Temperature Conditions and Reaction By-Products Presentation type:Poster Section:Ocean Sciences Session:General Contribution Authors:Takashi Teraji (1) Takemitsu Arakaki (2) AGU# 10173629 (1) Graduate School of Engineering and Science, University of the Ryukyus, 1 Senbaru Nishihara-cho, Okinawa, 903-0123, Japan (a4269bj@yahoo.co.jp), (2) Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, 1 Senbaru Nishihara-cho, Okinawa, 903-0123, Japan (arakakit@sci.u-ryukyu.ac.jp)

    Science.gov (United States)

    Teraji, T.; Arakaki, T.

    2011-12-01

    Use of artificial sweeteners in drinks and food has been rapidly increasing because of their non-calorie nature. In Japan, aspartame, acesulfame K and sucralose are among the most widely used artificial sweeteners. Because the artificial sweeteners are not metabolized in human bodies, they are directly excreted into the environment without chemical transformations. We initiated a study to better understand the fate of artificial sweeteners in the marine environment. In particular, we focused on the fate of aspartame by determining its bimolecular rate constants with hydroxyl radicals at various pH and temperature conditions and reaction by-products. The hydroxyl radical (OH), the most potent reactive oxygen species, reacts with various compounds and determines the environmental oxidation capacity and the life-time of many compounds. The steady-state OH concentration and the reaction rate constants between the compound and OH are used to estimate the life-time of the compound. In this study, we determine the bimolecular rate constants between aspartame and OH at various pH and temperature conditions using a competition kinetics technique. We use hydrogen peroxide as a photochemical source of OH. Bimolecular rate constant we obtained so far was (2.6±1.2)×109 M-1 s-1 at pH = 3.0. Little effect was seen by changing the temperatures between 15 and 40 °C. Activation energy (Ea) was calculated to be -1.0 kJ mol-1 at pH = 3.0, which could be regarded as zero. We will report reaction rate constants at different pHs and reaction by-products which will be analyzed by GC-MS. We will further discuss the fate of aspartame in the coastal environment.

  12. 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

  13. Mechanism of charge recombination in organic-inorganic hybrid perovskite solar cells

    Science.gov (United States)

    Yang, Wenchao; Yao, Yao; Wu, Chang-Qin; organic Group Team

    2015-03-01

    In the recent popular organic-inorganic hybrid perovskite solar cells, the slowness of the charge recombination processes is found to be a key factor for contributing to their high efficiencies and open circuit voltages, but the underlying mechanism remains unclear. In this work we study the recombination mechanism in perovskite solar cells and its roles on determining the device performance. Based on macroscopic device model simulations, the recombination resistances (Rrec) under different applied voltages are calculated to characterize the recombination mechanism, and the current density-voltage (J - V) curves are simulated to describe the device performance under at the same time. Through comparison with the impedance spectroscopy (IS) extracted Rrec data, it is found that bimolecular recombination (BR) is the dominant recombination process in the whole applied voltage regime and can determine the open circuit voltage, while the trap-assisted SRH monomolecular recombination (MR) is only important if the trap density is high or the BR rate is significantly reduced. The different electron injection barriers at the contact can induce different patterns for the Rrec- V characteristics. Under the cases of increased band gap or decreased BR rate, the Rrec's are enhanced which leads to high open circuit voltages. We are grateful to the support from the state key laboratory of surface physics, Fudan University.

  14. Bimolecular Recombination Kinetics of an Exciton-Trion Gas

    Science.gov (United States)

    2015-07-01

    The second and third reactions are catalytic agents for the loss of excitons. This implies that the constants R and S will appear only in the exciton...change the electron density. 3 Note that Reaction 3 in Table 2 is catalytic as defined above, because it changes the electron and e−trion...from the PL laser, which is fixed. Table 2 Reactions that change νe Reaction Rate Constant 1. νe + νh → ϕ A 2. νe + τh → Ex P 3

  15. A multilayered-representation quantum mechanical/molecular mechanics study of the SN2 reaction of CH3Br + OH- in aqueous solution

    Science.gov (United States)

    Xu, Yulong; Wang, Tingting; Wang, Dunyou

    2012-11-01

    The bimolecular nucleophilic substitution (SN2) reaction of CH3Br and OH- in aqueous solution was investigated using a multilayered-representation quantum mechanical and molecular mechanics methodology. Reactant complex, transition state, and product complex are identified and characterized in aqueous solution. The potentials of mean force are computed under both the density function theory and coupled-cluster single double (triple) (CCSD(T)) levels of theory for the reaction region. The results show that the aqueous environment has a significant impact on the reaction process. The solvation effect and the polarization effect combined raise the activation barrier height by ˜16.2 kcal/mol and the solvation effect is the dominant contribution to the potential of mean force. The CCSD(T)/MM representation presents a free energy activation barrier height of 22.8 kcal/mol and the rate constant at 298 K of 3.7 × 10-25 cm3 molecule-1 s-1 which agree very well with the experiment values at 23.0 kcal/mol and 2.6 × 10-25 cm3 molecule-1 s-1, respectively.

  16. A four-step mechanism for the formation of supported-nanoparticle heterogenous catalysts in contact with solution: the conversion of Ir(1,5-COD)Cl/γ-Al2O3 to Ir(0)(∼170)/γ-Al2O3.

    Science.gov (United States)

    Kent, Patrick D; Mondloch, Joseph E; Finke, Richard G

    2014-02-05

    Product stoichiometry, particle-size defocusing, and kinetic evidence are reported consistent with and supportive of a four-step mechanism of supported transition-metal nanoparticle formation in contact with solution: slow continuous nucleation, A → B (rate constant k1), autocatalytic surface growth, A + B → 2B (rate constant k2), bimolecular agglomeration, B + B → C (rate constant k3), and secondary autocatalytic surface growth, A + C → 1.5C (rate constant k4), where A is nominally the Ir(1,5-COD)Cl/γ-Al2O3 precursor, B the growing Ir(0) particles, and C the larger, catalytically active nanoparticles. The significance of this work is at least 4-fold: first, this is the first documentation of a four-step mechanism for supported-nanoparticle formation in contact with solution. Second, the proposed four-step mechanism, which was obtained following the disproof of 18 alternative mechanisms, is a new four-step mechanism in which the new fourth step is A + C → 1.5C in the presence of the solid, γ-Al2O3 support. Third, the four-step mechanism provides rare, precise chemical and kinetic precedent for metal particle nucleation, growth, and now agglomeration (B + B → C) and secondary surface autocatalytic growth (A + C → 1.5C) involved in supported-nanoparticle heterogeneous catalyst formation in contact with solution. Fourth, one now has firm, disproof-based chemical-mechanism precedent for two specific, balanced pseudoelementary kinetic steps and their precise chemical descriptors of bimolecular particle agglomeration, B + B → C, and autocatalytic agglomeration, B + C → 1.5C, involved in, for example, nanoparticle catalyst sintering.

  17. Pulmonary mechanics during mechanical ventilation.

    Science.gov (United States)

    Henderson, William R; Sheel, A William

    2012-03-15

    The use of mechanical ventilation has become widespread in the management of hypoxic respiratory failure. Investigations of pulmonary mechanics in this clinical scenario have demonstrated that there are significant differences in compliance, resistance and gas flow when compared with normal subjects. This paper will review the mechanisms by which pulmonary mechanics are assessed in mechanically ventilated patients and will review how the data can be used for investigative research purposes as well as to inform rational ventilator management.

  18. 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

  19. 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…

  20. 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

  1. Revealing a double-inversion mechanism for the F⁻+CH₃Cl SN2 reaction.

    Science.gov (United States)

    Szabó, István; Czakó, Gábor

    2015-01-19

    Stereo-specific reaction mechanisms play a fundamental role in chemistry. The back-side attack inversion and front-side attack retention pathways of the bimolecular nucleophilic substitution (SN2) reactions are the textbook examples for stereo-specific chemical processes. Here, we report an accurate global analytic potential energy surface (PES) for the F(-)+CH₃Cl SN2 reaction, which describes both the back-side and front-side attack substitution pathways as well as the proton-abstraction channel. Moreover, reaction dynamics simulations on this surface reveal a novel double-inversion mechanism, in which an abstraction-induced inversion via a FH···CH₂Cl(-) transition state is followed by a second inversion via the usual [F···CH₃···Cl](-) saddle point, thereby opening a lower energy reaction path for retention than the front-side attack. Quasi-classical trajectory computations for the F(-)+CH₃Cl(ν1=0, 1) reactions show that the front-side attack is a fast direct, whereas the double inversion is a slow indirect process.

  2. A mechanism regulating the onset of Sox2 expression in the embryonic neural plate.

    Directory of Open Access Journals (Sweden)

    Costis Papanayotou

    2008-01-01

    Full Text Available In vertebrate embryos, the earliest definitive marker for the neural plate, which will give rise to the entire central nervous system, is the transcription factor Sox2. Although some of the extracellular signals that regulate neural plate fate have been identified, we know very little about the mechanisms controlling Sox2 expression and thus neural plate identity. Here, we use electroporation for gain- and loss-of-function in the chick embryo, in combination with bimolecular fluorescence complementation, two-hybrid screens, chromatin immunoprecipitation, and reporter assays to study protein interactions that regulate expression of N2, the earliest enhancer of Sox2 to be activated and which directs expression to the largest part of the neural plate. We show that interactions between three coiled-coil domain proteins (ERNI, Geminin, and BERT, the heterochromatin proteins HP1alpha and HP1gamma acting as repressors, and the chromatin-remodeling enzyme Brm acting as activator control the N2 enhancer. We propose that this mechanism regulates the timing of Sox2 expression as part of the process of establishing neural plate identity.

  3. 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.

  4. Geometric mechanics

    CERN Document Server

    Muniz Oliva, Waldyr

    2002-01-01

    Geometric Mechanics here means mechanics on a pseudo-riemannian manifold and the main goal is the study of some mechanical models and concepts, with emphasis on the intrinsic and geometric aspects arising in classical problems. The first seven chapters are written in the spirit of Newtonian Mechanics while the last two ones as well as two of the four appendices describe the foundations and some aspects of Special and General Relativity. All the material has a coordinate free presentation but, for the sake of motivation, many examples and exercises are included in order to exhibit the desirable flavor of physical applications.

  5. 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.

  6. 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 ...

  7. 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...

  8. 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...

  9. Kinetic analysis of the multistep aggregation mechanism of monoclonal antibodies.

    Science.gov (United States)

    Nicoud, Lucrèce; Arosio, Paolo; Sozo, Margaux; Yates, Andrew; Norrant, Edith; Morbidelli, Massimo

    2014-09-11

    We investigate by kinetic analysis the aggregation mechanism of two monoclonal antibodies belonging to the IgG1 and IgG2 subclass under thermal stress. For each IgG, we apply a combination of size exclusion chromatography and light scattering techniques to resolve the time evolution of the monomer, dimer, and trimer concentrations, as well as the average molecular weight and the average hydrodynamic radius of the aggregate distribution. By combining the detailed experimental characterization with a theoretical kinetic model based on population balance equations, we extract relevant information on the contribution of the individual elementary steps on the global aggregation process. The analysis shows that the two molecules follow different aggregation pathways under the same operating conditions. In particular, while the monomer depletion of the IgG1 is found to be rate-limited by monomeric conformational changes, bimolecular collision is identified as the rate-limiting step in the IgG2 aggregation process. The measurement of the microscopic rate constants by kinetic analysis allows the quantification of the protein-protein interaction potentials expressed in terms of the Fuchs stability ratio (W). It is found that the antibody solutions exhibit large W values, which are several orders of magnitude larger than the values computed in the frame of the DLVO theory. This indicates that, besides net electrostatic repulsion, additional effects delay the aggregation kinetics of the antibody solutions with respect to diffusion-limited conditions. These effects likely include the limited efficiency of the collision events due to the presence of a limited number of specific aggregation-prone patches on the heterogeneous protein surface, and the contribution of additional repulsive non-DLVO forces to the protein-protein interaction potential, such as hydration forces.

  10. Mechanism of Formation of Copper(II) Chloro Complexes Revealed by Transient Absorption Spectroscopy and DFT/TDDFT Calculations.

    Science.gov (United States)

    Mereshchenko, Andrey S; Olshin, Pavel K; Karabaeva, Kanykey E; Panov, Maxim S; Wilson, R Marshall; Kochemirovsky, Vladimir A; Skripkin, Mikhail Yu; Tveryanovich, Yury S; Tarnovsky, Alexander N

    2015-07-16

    Copper(II) complexes are extremely labile with typical ligand exchange rate constants on the order of 10(6)-10(9) M(-1) s(-1). As a result, it is often difficult to identify the actual formation mechanism of these complexes. In this work, using UV-vis transient absorption when probing in a broad time range (20 ps to 8 μs) in conjunction with DFT/TDDFT calculations, we studied the dynamics and underlying reaction mechanisms of the formation of extremely labile copper(II) CuCl4(2-) chloro complexes from copper(II) CuCl3(-) trichloro complexes and chloride ions. These two species, produced via photochemical dissociation of CuCl4(2-) upon 420 nm excitation into the ligand-to-metal-charge-transfer electronic state, are found to recombine into parent complexes with bimolecular rate constants of (9.0 ± 0.1) × 10(7) and (5.3 ± 0.4) × 10(8) M(-1) s(-1) in acetonitrile and dichloromethane, respectively. In dichloromethane, recombination occurs via a simple one-step addition. In acetonitrile, where [CuCl3](-) reacts with the solvent to form a [CuCl3CH3CN](-) complex in less than 20 ps, recombination takes place via ligand exchange described by the associative interchange mechanism that involves a [CuCl4CH3CN](2-) intermediate. In both solvents, the recombination reaction is potential energy controlled.

  11. 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...... such mechanisms. This is a horizontal subject, which means you will be asked to make use of your knowledge in different disciplines, specially statics and dynamics, but also material selection, general product development, etc. At the end of this course you will be able to: • Generate alternative configurations...... for mechanisms that follow a particular trajectory, that need to occupy certain positions or that perform special functions using synthesis tools. • Analyze a mechanism from its kinematic characteristics (speed, velocity and acceleration) • Evaluate the best solution from different mechanisms configurations...

  12. Gauge mechanics

    CERN Document Server

    Mangiarotti, L

    1998-01-01

    This book presents in a unified way modern geometric methods in analytical mechanics based on the application of fibre bundles, jet manifold formalism and the related concept of connection. Non-relativistic mechanics is seen as a particular field theory over a one-dimensional base. In fact, the concept of connection is the major link throughout the book. In the gauge scheme of mechanics, connections appear as reference frames, dynamic equations, and in Lagrangian and Hamiltonian formalisms. Inertial forces, energy conservation laws and other phenomena related to reference frames are analyzed;

  13. Fluid mechanics

    CERN Document Server

    Kundu, Pijush K; Dowling, David R

    2011-01-01

    Fluid mechanics, the study of how fluids behave and interact under various forces and in various applied situations-whether in the liquid or gaseous state or both-is introduced and comprehensively covered in this widely adopted text. Revised and updated by Dr. David Dowling, Fluid Mechanics, 5e is suitable for both a first or second course in fluid mechanics at the graduate or advanced undergraduate level. Along with more than 100 new figures, the text has been reorganized and consolidated to provide a better flow and more cohesion of topics.Changes made to the

  14. 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

  15. 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.

  16. 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...

  17. 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...

  18. The structure of a thermostable mutant of pro-papain reveals its activation mechanism.

    Science.gov (United States)

    Roy, Sumana; Choudhury, Debi; Aich, Pulakesh; Dattagupta, Jiban K; Biswas, Sampa

    2012-12-01

    Papain is the archetype of a broad class of cysteine proteases (clan C1A) that contain a pro-peptide in the zymogen form which is required for correct folding and spatio-temporal regulation of proteolytic activity in the initial stages after expression. This study reports the X-ray structure of the zymogen of a thermostable mutant of papain at 2.6 Å resolution. The overall structure, in particular that of the mature part of the protease, is similar to those of other members of the family. The structure provides an explanation for the molecular basis of the maintenance of latency of the proteolytic activity of the zymogen by its pro-segment at neutral pH. The structural analysis, together with biochemical and biophysical studies, demonstrated that the pro-segment of the zymogen undergoes a rearrangement in the form of a structural loosening at acidic pH which triggers the proteolytic activation cascade. This study further explains the bimolecular stepwise autocatalytic activation mechanism by limited proteolysis of the zymogen of papain at the molecular level. The possible factors responsible for the higher thermal stability of the papain mutant have also been analyzed.

  19. Theoretical study of the oxidation mechanisms of naphthalene initiated by hydroxyl radicals: the H abstraction pathway.

    Science.gov (United States)

    Shiroudi, Abolfazl; Deleuze, Michael S

    2014-05-22

    Reaction mechanisms for the initial stages of naphthalene oxidation at high temperatures (T ≥ 600 K) have been studied theoretically using density functional theory along with various exchange-correlation functionals, as well as the benchmark CBS-QB3 quantum chemical approach. These stages correspond to the removal of hydrogen atoms by hydroxyl radical and the formation thereby of 1- and 2-naphthyl radicals. Bimolecular kinetic rate constants were estimated by means of transition state theory. The excellent agreement with the available experimental kinetic rate constants demonstrates that a two-step reaction scheme prevails. Comparison with results obtained with density functional theory in conjunction with various exchange-correlation functionals also shows that DFT remains unsuited for quantitative insights into kinetic rate constants. Analysis of the computed structures, bond orders, and free energy profiles demonstrates that the reaction steps involved in the removal of hydrogen atoms by OH radicals satisfy Hammond's principle. Computations of branching ratios also show that these reactions do not exhibit a particularly pronounced site-selectivity.

  20. Theoretical study on the reaction mechanism of CN radical with ketene

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The bimolecular single collision reaction potential energy surface of CN radical with ketene (CH2CO) was investigated by means of B3LYP and QCISD(T) methods. The calculated results indicate that there are three possible channels in the reaction. The first is an attack reaction by the carbon atom of CN at the carbon atom of the methylene of CH2CO to form the intermediate NCCH2CO followed by a rupture reaction of the C-C bond combined with -CO group to the products CH2CN+CO. The second is a direct addition reaction between CN and CH2CO to form the intermediate CH2C(O)CN followed by its isomerization into NCCH2CO via a CN-shift reaction, and subsequently, NCCH2CO dissociates into CH2CN+CO through a CO-loss reaction. The last is a direct hydrogen abstraction reaction of CH2CO by CN radical. Because of the existence of a 15.44 kJ/mol reaction barrier and higher energy of reaction products, the path can be ruled out as an important channel in the reaction kinetics. The present theoretical computation results, which give an available suggestion on the reaction mechanism, are in good agreement with previous experimental studies.

  1. Quantum Mechanics

    Science.gov (United States)

    Mandl, F.

    1992-07-01

    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 Scientists R. J. Barlow and A. R. Barnett Quantum Mechanics aims to teach those parts of the subject which every physicist should know. The object is to display the inherent structure of quantum mechanics, concentrating on general principles and on methods of wide applicability without taking them to their full generality. This book will equip students to follow quantum-mechanical arguments in books and scientific papers, and to cope with simple cases. To bring the subject to life, the theory is applied to the all-important field of atomic physics. No prior knowledge of quantum mechanics is assumed. However, it would help most readers to have met some elementary wave mechanics before. Primarily written for students, it should also be of interest to experimental research workers who require a good grasp of quantum mechanics without the full formalism needed by the professional theorist. Quantum Mechanics features: A flow diagram allowing topics to be studied in different orders or omitted altogether. Optional "starred" and highlighted sections containing more advanced and specialized material for the more ambitious reader. Sets of problems at the end of each chapter to help student understanding. Hints and solutions to the problems are given at the end of the book.

  2. Precision mechanics

    CERN Document Server

    Kittell, David

    1989-01-01

    David Kittell, the father of the discipline, Precision Mechanics, shares the foundation of this science with you in his highly practical and fun to read book, Precision Mechanics. Based on his highly acclaimed course by the same name, first taught at the Perkin-Elmer Technical institute in Norwalk, Connecticut, and later as a short course offered in such places as Bell Labs, SPIE, IEEE, NASA, and several national labs, you will find this book relevant and immediately useful.

  3. Fiscal 1997 report of the development of high efficiency waste power generation technology. No.2 volume. Pilot plant verification test; Kokoritsu haikibutsu hatsuden gijutsu kaihatsu (pilot plant jissho shiken). 1997 nendo hokokusho (daini bunsatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    As to a high efficiency waste power generation system using general waste as fuel, the details of the following were described: design/construction management and operational study of pilot plant, design/manufacture/construction of pilot plant, and study of an optimal total system. Concerning the construction management and operational study, the paper described the application for governmental/official inspection procedures and taking inspection, process management of pilot plant, site patrol, safety management, management of trial run of pilot plant, drawing-up of a verification test plan and test run, etc. Relating to the design/manufacture/construction of pilot plant, an outline of the pilot plant was described. The paper also stated points to be considered in design of furnace structure and boiler structure, points to be considered of the verification test, etc. As to the study of an optimal total system, the following were described: survey of waste gasification/slagging power generation technology, basic study on RDF production process, survey of trends of waste power generation technology in the U.S., etc. 52 refs., 149 figs., 121 tabs.

  4. Hybrid Quantum Mechanical and Molecular Mechanics Study of the SN2 Reaction of CCl4 + OH- in Aqueous Solution: The Potential of Mean Force, Reaction Energetics, and Rate Constants

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ting; Yin, Hongyun; Wang, Dunyou; Valiev, Marat

    2012-02-16

    The bimolecular nucleophilic substitution reaction of CCl{sub 4} and OH{sup -} in aqueous solution was investigated on the basis of a combined quantum mechanical and molecular mechanics method. A multilayered representation approach is employed to achieve high accuracy results at the CCSD(T) level of theory. The potential of mean force calculations at the DFT level and CCSD(T) level of theory yield reaction barrier heights of 22.7 and 27.9 kcal/mol, respectively. Both the solvation effects and the solvent-induced polarization effect have significant contributions to the reaction energetics, for example, the solvation effect raises the saddle point by 10.6 kcal/mol. The calculated rate constant coefficient is 8.6 x 10{sup -28} cm{sup 3} molecule{sup -1} s{sup -1} at the standard state condition, which is about 17 orders magnitude smaller than that in the gas phase. Among the four chloromethanes (CH{sub 3}Cl, CH{sub 2}Cl{sub 2}, CHCl{sub 3}, and CCl{sub 4}), CCl{sub 4} has the lowest free energy activation barrier for the reaction with OH{sup -1} in aqueous solution, confirming the trend that substitution of Cl by H in chloromethanes diminishes the reactivity.

  5. Wave Mechanics or Wave Statistical Mechanics

    Institute of Scientific and Technical Information of China (English)

    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.

  6. 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.

  7. 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.

  8. 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...

  9. Computational mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Raboin, P J

    1998-01-01

    The Computational Mechanics thrust area is a vital and growing facet of the Mechanical Engineering Department at Lawrence Livermore National Laboratory (LLNL). This work supports the development of computational analysis tools in the areas of structural mechanics and heat transfer. Over 75 analysts depend on thrust area-supported software running on a variety of computing platforms to meet the demands of LLNL programs. Interactions with the Department of Defense (DOD) High Performance Computing and Modernization Program and the Defense Special Weapons Agency are of special importance as they support our ParaDyn project in its development of new parallel capabilities for DYNA3D. Working with DOD customers has been invaluable to driving this technology in directions mutually beneficial to the Department of Energy. Other projects associated with the Computational Mechanics thrust area include work with the Partnership for a New Generation Vehicle (PNGV) for ''Springback Predictability'' and with the Federal Aviation Administration (FAA) for the ''Development of Methodologies for Evaluating Containment and Mitigation of Uncontained Engine Debris.'' In this report for FY-97, there are five articles detailing three code development activities and two projects that synthesized new code capabilities with new analytic research in damage/failure and biomechanics. The article this year are: (1) Energy- and Momentum-Conserving Rigid-Body Contact for NIKE3D and DYNA3D; (2) Computational Modeling of Prosthetics: A New Approach to Implant Design; (3) Characterization of Laser-Induced Mechanical Failure Damage of Optical Components; (4) Parallel Algorithm Research for Solid Mechanics Applications Using Finite Element Analysis; and (5) An Accurate One-Step Elasto-Plasticity Algorithm for Shell Elements in DYNA3D.

  10. Mechanical instability

    CERN Document Server

    Krysinski, Tomasz

    2013-01-01

    This book presents a study of the stability of mechanical systems, i.e. their free response when they are removed from their position of equilibrium after a temporary disturbance. After reviewing the main analytical methods of the dynamical stability of systems, it highlights the fundamental difference in nature between the phenomena of forced resonance vibration of mechanical systems subjected to an imposed excitation and instabilities that characterize their free response. It specifically develops instabilities arising from the rotor-structure coupling, instability of control systems, the se

  11. 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

  12. 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

  13. Classical Mechanics

    OpenAIRE

    Gallavotti, Giovanni

    2012-01-01

    This is the English version of a friendly graduate course on Classical Mechanics, containing about 80% of the material I covered during the January-June 1999 semester at IFUG in the Mexican city of Leon. For the Spanish version, see physics/9906066

  14. 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)

  15. 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...

  16. 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...

  17. 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.

  18. Mechanical graphene

    Science.gov (United States)

    Socolar, Joshua E. S.; Lubensky, Tom C.; Kane, Charles L.

    2017-02-01

    We present a model of a mechanical system with a vibrational mode spectrum identical to the spectrum of electronic excitations in a tight-binding model of graphene. The model consists of point masses connected by elastic couplings, called ‘tri-bonds’, that implement certain three-body interactions, which can be tuned by varying parameters that correspond to the relative hopping amplitudes on the different bond directions in graphene. In the mechanical model, this is accomplished by varying the location of a pivot point that determines the allowed rigid rotations of a single tri-bond. The infinite system constitutes a Maxwell lattice, with the number of degrees of freedom equal to the number of constraints imposed by the tri-bonds. We construct the equilibrium and compatibility matrices and analyze the model’s phase diagram, which includes spectra with Weyl points for some placements of the pivot and topologically polarized phases for others. We then discuss the edge modes and associated states of self stress for strips cut from the periodic lattice. Finally, we suggest a physical realization of the tri-bond, which allows access to parameter regimes not available to experiments on (strained) graphene and may be used to create other two-dimensional mechanical metamaterials with different spectral features.

  19. 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

  20. 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

  1. Quantum mechanics

    CERN Document Server

    Zagoskin, Alexandre

    2015-01-01

    Written by Dr Alexandre Zagoskin, who is a Reader at Loughborough University, Quantum Mechanics: A Complete Introduction is designed to give you everything you need to succeed, all in one place. It covers the key areas that students are expected to be confident in, outlining the basics in clear jargon-free English, and then providing added-value features like summaries of key ideas, and even lists of questions you might be asked in your exam. The book uses a structure that is designed to make quantum physics as accessible as possible - by starting with its similarities to Newtonian physics, ra

  2. Superoxide reductase from Desulfoarculus baarsii: reaction mechanism and role of glutamate 47 and lysine 48 in catalysis

    CERN Document Server

    Lombard, M; Touati, D; Fontecave, M; Nivière, V

    2015-01-01

    Superoxide reductase (SOR) is a small metalloenzyme that catalyzes reduction of O(2)(*)(-) to H(2)O(2) and thus provides an antioxidant mechanism against superoxide radicals. Its active site contains an unusual mononuclear ferrous center, which is very efficient during electron transfer to O(2)(*)(-) [Lombard, M., Fontecave, M., Touati, D., and Nivi{\\`e}re, V. (2000) J. Biol. Chem. 275, 115-121]. The reaction of the enzyme from Desulfoarculus baarsii with superoxide was studied by pulse radiolysis methods. The first step is an extremely fast bimolecular reaction of superoxide reductase with superoxide, with a rate constant of (1.1 +/- 0.3) x 10(9) M(-1) s(-1). A first intermediate is formed which is converted to a second one at a much slower rate constant of 500 +/- 50 s(-1). Decay of the second intermediate occurs with a rate constant of 25 +/- 5 s(-1). These intermediates are suggested to be iron-superoxide and iron-peroxide species. Furthermore, the role of glutamate 47 and lysine 48, which are the closest...

  3. On the reaction mechanism of the complete intermolecular O2 transfer between mononuclear nickel and manganese complexes with macrocyclic ligands.

    Science.gov (United States)

    Zapata-Rivera, Jhon; Caballol, Rosa; Calzado, Carmen J; Liakos, Dimitrios G; Neese, Frank

    2014-10-01

    The recently described intermolecular O2 transfer between the side-on Ni-O2 complex [(12-TMC)Ni-O2](+) and the manganese complex [(14-TMC)Mn](2+), where 12-TMC and 14-TMC are 12- and 14-membered macrocyclic ligands, 12-TMC=1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane and 14-TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, is studied by means of DFT methods. B3LYP calculations including long-range corrections and solvent effects are performed to elucidate the mechanism. The potential energy surfaces (PESs) compatible with different electronic states of the reactants have been analyzed. The calculations confirm a two-step reaction, with a first rate-determining bimolecular step and predict the exothermic character of the global process. The relative stability of the products and the reverse barrier are in line with the fact that no reverse reaction is experimentally observed. An intermediate with a μ-η(1):η(1)-O2 coordination and two transition states are identified on the triplet PES, slightly below the corresponding stationary points of the quintet PES, suggesting an intersystem crossing before the first transition state. The calculated activation parameters and the relative energies of the two transition sates and the products are in very good agreement with the experimental data. The calculations suggest that a superoxide anion is transferred during the reaction.

  4. Dynamic Reaction Mechanisms of ClO(-) with CH3Cl: Comparison Between Direct Dynamics Trajectory Simulations and Experiment.

    Science.gov (United States)

    Yu, Feng

    2016-03-24

    We have investigated the dynamic reaction mechanisms of *ClO¯ with CH3Cl (the asterisk is utilized to label a different Cl atom). Ab initio molecular dynamics simulations at the MP2/6-31+G(d,p) level of theory have been employed to compute the dynamic trajectories. On the basis of our simulations, the dynamic reaction pathways for the bimolecular nucleophilic substitution (SN2) reaction channel and SN2-induced elimination reaction channel are clearly illustrated. For the SN2 reaction channel, some trajectories directly dissociate to the final products of CH3O*Cl and Cl¯, whereas the others involve the dynamic Cl¯···CH3O*Cl intermediate complex. As to the SN2-induced elimination reaction channel, the trajectories lead to the final products of CH2O, HCl, and *Cl¯ through the dynamic Cl¯···CH3O*Cl intermediate complex. More significantly, the product branching ratios of Cl¯ and *Cl¯ predicted by our simulations are basically consistent with previous experimental results (Villano et al. J. Am. Chem. Soc. 2009, 131, 8227-8233).

  5. Pre-steady-state Kinetics Reveal the Substrate Specificity and Mechanism of Halide Oxidation of Truncated Human Peroxidasin 1*

    Science.gov (United States)

    Paumann-Page, Martina; Katz, Romy-Sophie; Bellei, Marzia; Schwartz, Irene; Edenhofer, Eva; Sevcnikar, Benjamin; Soudi, Monika

    2017-01-01

    Human peroxidasin 1 is a homotrimeric multidomain peroxidase that is secreted to the extracellular matrix. The heme enzyme was shown to release hypobromous acid that mediates the formation of specific covalent sulfilimine bonds to reinforce collagen IV in basement membranes. Maturation by proteolytic cleavage is known to activate the enzyme. Here, we present the first multimixing stopped-flow study on a fully functional truncated variant of human peroxidasin 1 comprising four immunoglobulin-like domains and the catalytically active peroxidase domain. The kinetic data unravel the so far unknown substrate specificity and mechanism of halide oxidation of human peroxidasin 1. The heme enzyme is shown to follow the halogenation cycle that is induced by the rapid H2O2-mediated oxidation of the ferric enzyme to the redox intermediate compound I. We demonstrate that chloride cannot act as a two-electron donor of compound I, whereas thiocyanate, iodide, and bromide efficiently restore the ferric resting state. We present all relevant apparent bimolecular rate constants, the spectral signatures of the redox intermediates, and the standard reduction potential of the Fe(III)/Fe(II) couple, and we demonstrate that the prosthetic heme group is post-translationally modified and cross-linked with the protein. These structural features provide the basis of human peroxidasin 1 to act as an effective generator of hypobromous acid, which mediates the formation of covalent cross-links in collagen IV. PMID:28154175

  6. Soliton mechanics

    Science.gov (United States)

    Gunasekaran, Sharmila; Hussain, Uzair; Kunduri, Hari K.

    2016-12-01

    The domain of outer communication of five-dimensional asymptotically flat stationary spacetimes may possess nontrivial 2-cycles (bubbles). Spacetimes containing such 2-cycles can have nonzero energy, angular momenta, and charge even in the absence of horizons. A mass variation formula has been established for spacetimes containing bubbles and possibly a black hole horizon. This "first law of black hole and soliton mechanics" contains new intensive and extensive quantities associated with each 2-cycle. We consider examples of such spacetimes for which we explicitly calculate these quantities and show how regularity is essential for the formulas relating them to hold. We also derive new explicit expressions for the angular momenta and charge for spacetimes containing solitons purely in terms of fluxes supporting the bubbles.

  7. Soliton mechanics

    CERN Document Server

    Gunasekaran, Sharmila; Kunduri, Hari K

    2016-01-01

    The domain of outer communication of five-dimensional asymptotically flat stationary spacetimes may possess non-trivial 2-cycles (bubbles). Spacetimes containing such 2-cycles can have non-zero energy, angular momenta, and charge even in the absence of horizons. A mass variation formula has been established for spacetimes containing bubbles and possibly a black hole horizon. This `first law of black hole and soliton mechanics' contains new intensive and extensive quantities associated to each 2-cycle. We consider examples of such spacetimes for which we explicitly calculate these quantities and show how regularity is essential for the formulae relating them to hold. We also derive new explicit expressions for the angular momenta and charge for spacetimes containing solitons purely in terms of fluxes supporting the bubbles.

  8. Fracture mechanics

    Science.gov (United States)

    Shannon, John L., Jr.

    1986-01-01

    The application of fracture mechanics to the design of ceramic structures will require the precise measurement of crack growth and fracture resistance of these materials over their entire range of anticipated service temperatures and standardized test methods for making such measurements. The development of a standard test for measuring the plane strain fracture toughness is sought. Stress intensity factor coefficients were determined for three varieties of chevron-notch specimens, and fracture toughness measurements were made on silicon nitrides, silicon carbides, and aluminum oxides to assess the performance of each specimen variety. It was determined that silicon nitride and silicon carbides have flat crack growth resistance curves, but aluminum oxide does not. Additionally, batch-to-batch differences were noticed for the aluminum oxide. Experiments are continuing to explain the rising crack growth resistance and batch-to-batch variations for the aluminum oxide.

  9. Treatment of statin compounds by advanced oxidation processes: Kinetic considerations and destruction mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Razavi, Behnaz, E-mail: brazavi@uci.ed [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175 (United States); Song Weihua, E-mail: wsong@uci.ed [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175 (United States); Santoke, Hanoz, E-mail: hsantoke@uci.ed [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175 (United States); Cooper, William J., E-mail: wcooper@uci.ed [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175 (United States)

    2011-03-15

    This study examined the use of advanced oxidation/reduction processes (AO/RPs) for the destruction of cholesterol lowering statin pharmaceuticals. AO/RPs which utilize the oxidizing hydroxyl radical ({sup {center_dot}O}H) and reducing aqueous electron (e{sup -}{sub aq}), to degrade chemical contaminants are alternatives to traditional water treatment methods, and are alternatives as water reuse becomes more generally implemented. Four major statin pharmaceuticals, fluvastatin, lovastatin, pravastatin and simvastatin, were studied, and the absolute bimolecular reaction rate constants with {sup {center_dot}O}H determined, (6.96{+-}0.16)x10{sup 9}, (2.92{+-}0.06)x10{sup 9}, (4.16{+-}0.13)x10{sup 9}, and (3.13{+-}0.15)x10{sup 9} M{sup -1} s{sup -1}, and for e{sup -}{sub aq} (2.31{+-}0.06)x10{sup 9}, (0.45{+-}0.01)x10{sup 9}, (1.26{+-}0.01)x10{sup 9}, and (0.69{+-}0.02)x10{sup 9} M{sup -1} s{sup -1}, respectively. To provide additional information on the radicals formed upon oxidation, transient spectra were measured and the overall reaction efficiency determined. Radical-based destruction mechanisms for destruction of the statins are proposed based on the LC-MS determination of the stable reaction by-products formed using {sup 137}Cs {gamma}-irradiation of statin solutions. Knowing the reaction rates, reaction efficiencies and destruction mechanisms of these compounds is essential for the consideration of the use of advanced oxidation/reduction processes for the destruction of statins in aqueous systems.

  10. Treatment of statin compounds by advanced oxidation processes: Kinetic considerations and destruction mechanisms

    Science.gov (United States)

    Razavi, Behnaz; Song, Weihua; Santoke, Hanoz; Cooper, William J.

    2011-03-01

    This study examined the use of advanced oxidation/reduction processes (AO/RPs) for the destruction of cholesterol lowering statin pharmaceuticals. AO/RPs which utilize the oxidizing hydroxyl radical ( rad OH) and reducing aqueous electron (e -aq), to degrade chemical contaminants are alternatives to traditional water treatment methods, and are alternatives as water reuse becomes more generally implemented. Four major statin pharmaceuticals, fluvastatin, lovastatin, pravastatin and simvastatin, were studied, and the absolute bimolecular reaction rate constants with rad OH determined, (6.96±0.16)×10 9, (2.92±0.06)×10 9, (4.16±0.13)×10 9, and (3.13±0.15)×10 9 M -1 s -1, and for e -aq (2.31±0.06)×10 9, (0.45±0.01)×10 9, (1.26±0.01)×10 9, and (0.69±0.02)×10 9 M -1 s -1, respectively. To provide additional information on the radicals formed upon oxidation, transient spectra were measured and the overall reaction efficiency determined. Radical-based destruction mechanisms for destruction of the statins are proposed based on the LC-MS determination of the stable reaction by-products formed using 137Cs γ-irradiation of statin solutions. Knowing the reaction rates, reaction efficiencies and destruction mechanisms of these compounds is essential for the consideration of the use of advanced oxidation/reduction processes for the destruction of statins in aqueous systems.

  11. INDEXING MECHANISM

    Science.gov (United States)

    Kock, L.J.

    1959-09-22

    A device is presented for loading and unloading fuel elements containing material fissionable by neutrons of thermal energy. The device comprises a combination of mechanical features Including a base, a lever pivotally attached to the base, an Indexing plate on the base parallel to the plane of lever rotation and having a plurality of apertures, the apertures being disposed In rows, each aperture having a keyway, an Index pin movably disposed to the plane of lever rotation and having a plurality of apertures, the apertures being disposed in rows, each aperture having a keyway, an index pin movably disposed on the lever normal to the plane rotation, a key on the pin, a sleeve on the lever spaced from and parallel to the index pin, a pair of pulleys and a cable disposed between them, an open collar rotatably attached to the sleeve and linked to one of the pulleys, a pin extending from the collar, and a bearing movably mounted in the sleeve and having at least two longitudinal grooves in the outside surface.

  12. Umbilical mechanism

    Science.gov (United States)

    Barron, Daniel R. (Inventor); Jasulaitis, Vytas (Inventor); Morrill, Brion F. (Inventor)

    1995-01-01

    Apparatus is described for automatically mating a pair of connectors and protecting them prior to mating, which minimizes weight and uses relatively simple and reliable mechanisms. Lower and upper connectors (24, 26) are held in lower and upper parts (14, 16) of a housing, with the upper connector mounted on a carrier (32) that is motor driven to move down and mate the connectors. A pair of movable members (36, 38) serve as shields, as coarse alignment aids, and as force transmitters. The movable members are pivotally mounted at the bottom of the upper housing, and as the carrier moves down it pivots the members out of the way. The movable members have socket elements (116) that closely receive pin elements (120) on the lower housing part, to coarsely align the connectors and to react mating and unmating forces between the housings. The carrier has a pair of plate portions (60, 62) with slots (64), and the movable members have cam followers engaged with the slot walls, to move the members with precision. The carrier plate-like portions engage follower members (82) that pivot open lower shield parts (44, 46) covering the lower connector, which is mounted on four stacks of Belleville washers (142).

  13. Charge-transfer mechanism for electrophilic aromatic nitration and nitrosation via the convergence of (ab initio) molecular-orbital and Marcus-Hush theories with experiments.

    Science.gov (United States)

    Gwaltney, Steven R; Rosokha, Sergiy V; Head-Gordon, Martin; Kochi, Jay K

    2003-03-19

    The highly disparate rates of aromatic nitrosation and nitration, despite the very similar (electrophilic) properties of the active species: NO(+) and NO(2)(+) in Chart 1, are quantitatively reconciled. First, the thorough mappings of the potential-energy surfaces by high level (ab initio) molecular-orbital methodologies involving extensive coupled-cluster CCSD(T)/6-31G optimizations establish the intervention of two reactive intermediates in nitration (Figure 8) but only one in nitrosation (Figure 7). Second, the same distinctive topologies involving double and single potential-energy minima (Figures 6 and 5) also emerge from the semiquantitative application of the Marcus-Hush theory to the transient spectral data. Such a striking convergence from quite different theoretical approaches indicates that the molecular-orbital and Marcus-Hush (potential-energy) surfaces are conceptually interchangeable. In the resultant charge-transfer mechanism, the bimolecular interactions of arene donors with both NO(+) and NO(2)(+) spontaneously lead (barrierless) to pi-complexes in which electron transfer is concurrent with complexation. Such a pi-complex in nitration is rapidly converted to the sigma-complex, whereas this Wheland adduct in nitrosation merely represents a high energy (transition-state) structure. Marcus-Hush analysis thus demonstrates how the strongly differentiated (arene) reactivities toward NO(+) and NO(2)(+) can actually be exploited in the quantitative development of a single coherent (electron-transfer) mechanism for both aromatic nitrosation and nitration.

  14. Mechanical Design

    Energy Technology Data Exchange (ETDEWEB)

    Shook, Richard; /Marquette U. /SLAC

    2010-08-25

    The particle beam of the SXR (soft x-ray) beam line in the LCLS (Linac Coherent Light Source) has a high intensity in order to penetrate through samples at the atomic level. However, the intensity is so high that many experiments fail because of severe damage. To correct this issue, attenuators are put into the beam line to reduce this intensity to a level suitable for experimentation. Attenuation is defined as 'the gradual loss in intensity of any flux through a medium' by [1]. It is found that Beryllium and Boron Carbide can survive the intensity of the beam. At very thin films, both of these materials work very well as filters for reducing the beam intensity. Using a total of 12 filters, the first 9 being made of Beryllium and the rest made of Boron Carbide, the beam's energy range of photons can be attenuated between 800 eV and 9000 eV. The design of the filters allows attenuation for different beam intensities so that experiments can obtain different intensities from the beam if desired. The step of attenuation varies, but is relative to the thickness of the filter as a power function of 2. A relationship for this is f(n) = x{sub 0}2{sup n} where n is the step of attenuation desired and x{sub 0} is the initial thickness of the material. To allow for this desired variation, a mechanism must be designed within the test chamber. This is visualized using a 3D computer aided design modeling tool known as Solid Edge.

  15. Mechanism of mechanical activation for sulfide ores

    Institute of Scientific and Technical Information of China (English)

    HU Hui-ping; CHEN Qi-yuan; YIN Zhou-lan; HE Yue-hui; HUANG Bai-yun

    2007-01-01

    Structural changes for mechanically activated pyrite, sphalerite, galena and molybdenite with or without the exposure to ambient air, were systematically investigated using X-ray diffraction analysis(XRD), particle size analysis, gravimetrical method, X-ray photo-electron spectroscopy(XPS) and scanning electron microscopy(SEM), respectively. Based on the above structural changes for mechanically activated sulfide ores and related reports by other researchers, several qualitative rules of the mechanisms and the effects of mechanical activation for sulfide ores are obtained. For brittle sulfide ores with thermal instability, and incomplete cleavage plane or extremely incomplete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with thermal instability, and complete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed, and lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with excellent thermal stability, and complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For sulfide ores with high toughness, good thermal stability and very excellent complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation, but the lattice deformation ratio is very small. The effects of mechanical activation are worst.

  16. New insights into the molecular mechanisms of thrombosis from high resolution surface enhanced Raman microscopy

    Science.gov (United States)

    Keyes, Tia E.; Leane, Deirdre; Forster, Robert J.; Moran, Niamh; Kenny, Dermot

    2005-06-01

    Occlusion of a blood vessel due to thrombosis can reduce or completely stop blood supply to different tissues or organs with the clinical consequences of myocardial infarction or stroke. Platelets are the cellular component which initiate thrombus formation, they activate in response to a variety of signals, such as interactions with a damaged blood vessel. αIIbβ3 is a membrane bound integrin protein responsible for regulating adhesion of the activated platelet to damaged blood vessels. It exists in both activated and non-activated states displaying high and low affinity respectively for ligands such as fibrinogen. αIIbβ3 determines the "stickiness" of the blood platelet and is therefore, a logical target for therapeutic measures to control thrombus formation. During the past decade considerable progress has been made to identify the role of the αIIbβ3 complex in platelet-mediated thrombus formation and the structure of αIIbβ3 has been extrapolated from the crystal structure of related integrins. However, despite these advances, the bimolecular mechanisms underlying the activation of αIIbβ3 remain poorly understood. In this contribution, we describe methodologies of deriving surface enhanced Raman spectroscopy of αIIbβ3 on nanostructured metal surfaces, fabricated by a number of methods. We compare activation of αIIbβ3 by SERS using a range of known activation conditions including Mn(II), EDTA and dithiotheritol (DTT). By studying the behaviour of the disulfide and CS marker vibrations in the spectral region 400 to 800 cm-1 using SERS we confirm that activation results in significant conformational change in the protein, and most interestingly, that the response is not the same for every agonist. This mechanistic difference has implications for the biochemical study of this protein (and indeed for understanding the role of this integrin in response to different agonists).

  17. Conservation of structure and mechanism in primary and secondary transporters exemplified by SiaP, a sialic acid binding virulence factor from Haemophilus influenzae.

    Science.gov (United States)

    Müller, Axel; Severi, Emmanuele; Mulligan, Christopher; Watts, Andrew G; Kelly, David J; Wilson, Keith S; Wilkinson, Anthony J; Thomas, Gavin H

    2006-08-04

    Extracytoplasmic solute receptors (ESRs) are important components of solute uptake systems in bacteria, having been studied extensively as parts of ATP binding cassette transporters. Herein we report the first crystal structure of an ESR protein from a functionally characterized electrochemical ion gradient dependent secondary transporter. This protein, SiaP, forms part of a tripartite ATP-independent periplasmic transporter specific for sialic acid in Haemophilus influenzae. Surprisingly, the structure reveals an overall topology similar to ATP binding cassette ESR proteins, which is not apparent from the sequence, demonstrating that primary and secondary transporters can share a common structural component. The structure of SiaP in the presence of the sialic acid analogue 2,3-didehydro-2-deoxy-N-acetylneuraminic acid reveals the ligand bound in a deep cavity with its carboxylate group forming a salt bridge with a highly conserved Arg residue. Sialic acid binding, which obeys simple bimolecular association kinetics as determined by stopped-flow fluorescence spectroscopy, is accompanied by domain closure about a hinge region and the kinking of an alpha-helix hinge component. The structure provides insight into the evolution, mechanism, and substrate specificity of ESR-dependent secondary transporters that are widespread in prokaryotes.

  18. Mechanism of charge recombination in meso-structured organic-inorganic hybrid perovskite solar cells: A macroscopic perspective

    Science.gov (United States)

    Yang, Wenchao; Yao, Yao; Wu, Chang-Qin

    2015-04-01

    In the currently popular organic-inorganic hybrid perovskite solar cells, the slowness of the charge recombination processes is found to be a key factor for contributing to their high efficiencies and high open circuit voltages, but the underlying recombination mechanism remains unclear. In this work, we investigate the bimolecular recombination (BR) and the trap-assisted monomolecular recombination (MR) in meso-structured perovskite solar cells under steady state working condition, and try to reveal their roles on determining the device performance. Some interfacial effects such as the injection barriers at the selective contacts are examined as well. Based on the macroscopic device modeling, the recombination resistance-voltage (Rrec-V) and the current density-voltage (J-V) curves are calculated to characterize the recombination mechanism and describe the device performance, respectively. Through comparison with the impedance spectroscopy extracted Rrec data, it is found that under the typical BR reduction factor and deep trap densities observed in experiments, the MR dominates the charge recombination in the low voltage regime, while the BR dominates in the high voltage regime. The short circuit current and the fill factor could be reduced by the significant MR but the open circuit voltage is generally determined by the BR. The different electron injection barriers at the contact can change the BR rate and induce different patterns for the Rrec-V characteristics. For the perovskites of increased band gaps, the Rrec's are significantly enhanced, corresponding to the high open circuit voltages. Finally, it is revealed that the reduced effective charge mobility due to the transport in electron and hole transporting material makes the Rrec decrease slowly with the increasing voltage, which leads to increased open circuit voltage.

  19. Mechanism of charge recombination in meso-structured organic-inorganic hybrid perovskite solar cells: A macroscopic perspective

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wenchao; Yao, Yao, E-mail: yaoyao@fudan.edu.cn; Wu, Chang-Qin, E-mail: cqw@fudan.edu.cn [State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China)

    2015-04-21

    In the currently popular organic-inorganic hybrid perovskite solar cells, the slowness of the charge recombination processes is found to be a key factor for contributing to their high efficiencies and high open circuit voltages, but the underlying recombination mechanism remains unclear. In this work, we investigate the bimolecular recombination (BR) and the trap-assisted monomolecular recombination (MR) in meso-structured perovskite solar cells under steady state working condition, and try to reveal their roles on determining the device performance. Some interfacial effects such as the injection barriers at the selective contacts are examined as well. Based on the macroscopic device modeling, the recombination resistance-voltage (R{sub rec}−V) and the current density-voltage (J–V) curves are calculated to characterize the recombination mechanism and describe the device performance, respectively. Through comparison with the impedance spectroscopy extracted R{sub rec} data, it is found that under the typical BR reduction factor and deep trap densities observed in experiments, the MR dominates the charge recombination in the low voltage regime, while the BR dominates in the high voltage regime. The short circuit current and the fill factor could be reduced by the significant MR but the open circuit voltage is generally determined by the BR. The different electron injection barriers at the contact can change the BR rate and induce different patterns for the R{sub rec}–V characteristics. For the perovskites of increased band gaps, the R{sub rec}'s are significantly enhanced, corresponding to the high open circuit voltages. Finally, it is revealed that the reduced effective charge mobility due to the transport in electron and hole transporting material makes the R{sub rec} decrease slowly with the increasing voltage, which leads to increased open circuit voltage.

  20. The Mechanics of Mechanical Watches and Clocks

    CERN Document Server

    Du, Ruxu

    2013-01-01

    "The Mechanics of Mechanical Watches and Clocks" presents historical views and mathematical models of mechanical watches and clocks. Although now over six hundred years old, mechanical watches and clocks are still popular luxury items that fascinate many people around the world. However few have examined the theory of how they work as presented in this book. The illustrations and computer animations are unique and have never been published before. It will be of significant interest to researchers in mechanical engineering, watchmakers and clockmakers, as well as people who have an engineering background and are interested in mechanical watches and clocks. It will also inspire people in other fields of science and technology, such as mechanical engineering and electronics engineering, to advance their designs. Professor Ruxu Du works at the Chinese University of Hong Kong, China. Assistant Professor Longhan Xie works at the South China University of Technology, China.

  1. Mechanical engineering education

    CERN Document Server

    Davim, J Paulo

    2012-01-01

    Mechanical Engineering is defined nowadays as a discipline "which involves the application of principles of physics, design, manufacturing and maintenance of mechanical systems". Recently, mechanical engineering has also focused on some cutting-edge subjects such as nanomechanics and nanotechnology, mechatronics and robotics, computational mechanics, biomechanics, alternative energies, as well as aspects related to sustainable mechanical engineering.This book covers mechanical engineering higher education with a particular emphasis on quality assurance and the improvement of academic

  2. Mechanical engineer's handbook

    CERN Document Server

    Marghitu, Dan B

    2001-01-01

    The Mechanical Engineer's Handbook was developed and written specifically to fill a need for mechanical engineers and mechanical engineering students throughout the world. With over 1000 pages, 550 illustrations, and 26 tables the Mechanical Engineer's Handbook is very comprehensive, yet affordable, compact, and durable. The Handbook covers all major areas of mechanical engineering with succinct coverage of the definitions, formulas, examples, theory, proofs, and explanations of all principle subject areas. The Handbook is an essential, practical companion for all mechanic

  3. Tokamak engineering mechanics

    CERN Document Server

    Song, Yuntao; Du, Shijun

    2013-01-01

    Tokamak Engineering Mechanics offers concise and thorough coverage of engineering mechanics theory and application for tokamaks, and the material is reinforced by numerous examples. Chapter topics include general principles, static mechanics, dynamic mechanics, thermal fluid mechanics and multiphysics structural mechanics of tokamak structure analysis. The theoretical principle of the design and the methods of the analysis for various components and load conditions are presented, while the latest engineering technologies are also introduced. The book will provide readers involved in the study

  4. Advances in Applied Mechanics

    OpenAIRE

    2014-01-01

    Advances in Applied Mechanics draws together recent significant advances in various topics in applied mechanics. Published since 1948, Advances in Applied Mechanics aims to provide authoritative review articles on topics in the mechanical sciences, primarily of interest to scientists and engineers working in the various branches of mechanics, but also of interest to the many who use the results of investigations in mechanics in various application areas, such as aerospace, chemical, civil, en...

  5. Mechanics of machinery

    CERN Document Server

    Mostafa, Mahmoud A

    2012-01-01

    MechanismsDefinitions Degrees of Freedom of Planar Mechanisms Four-Revolute-Pairs Chains Single-Slider Chain Double-Slider Mechanisms Mechanisms with Higher Pairs Compound Mechanisms Special Mechanisms Analytical Position Analysis of Mechanisms Velocities and AccelerationsAbsolute Plane Motion of a Particle Relative Motion Applications to Common Links Analysis of Mechanisms: Graphical Method Method of Instantaneous Centers for Determining the VelocitiesAnalytical Analysis CamsIntroduction Types of Cams Modes of Input/Output Motion Follower Configurations Classes of Cams Spur GearsIntroduction

  6. Analytical mechanics for relativity and quantum mechanics

    CERN Document Server

    Johns, Oliver Davis

    2011-01-01

    Analytical Mechanics for Relativity and Quantum Mechanics is an innovative and mathematically sound treatment of the foundations of analytical mechanics and the relation of classical mechanics to relativity and quantum theory. It is intended for use at the introductory graduate level. A distinguishing feature of the book is its integration of special relativity into teaching of classical mechanics. After a thorough review of the traditional theory, Part II of the book introduces extended Lagrangian and Hamiltonian methods that treat time as a transformable coordinate rather than the fixed parameter of Newtonian physics. Advanced topics such as covariant Langrangians and Hamiltonians, canonical transformations, and Hamilton-Jacobi methods are simplified by the use of this extended theory. And the definition of canonical transformation no longer excludes the Lorenz transformation of special relativity. This is also a book for those who study analytical mechanics to prepare for a critical exploration of quantum...

  7. Kinetic modeling of mechanisms of industrially important organic reactions in gas and liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Vahteristo, K.

    2010-07-01

    -trans and skeletal isomerization. Minor side reaction were dimerization and fragmentation. Monomolecular and bimolecular reaction mechanisms for skeletal isomerization explained experimental results almost equally well. Pseudohomogeneous kinetic parameters of reactions 1 and 2 were estimated by usual least squares fitting. Concerning reactions 3 and 4 kinetic parameters were estimated by the leastsquares method, but also the possible cross-correlation and identifiability of parameters were determined using Markov chain Monte Carlo (MCMC) method. Finally using MCMC method, the estimation of model parameters and predictions were performed according to the Bayesian paradigm. According to the fitting results suggested reaction mechanisms explained experimental results rather well. When the possible cross-correlation and identifiability of parameters (Reactions 3 and 4) were determined using MCMC method, the parameters identified well, and no pathological cross-correlation could be seen between any parameter pair. (orig.)

  8. Robust Design of Sounds in Mechanical Mechanisms

    DEFF Research Database (Denmark)

    Boegedal Jensen, Annemette; Munch, Natasja; Howard, Thomas J.;

    2015-01-01

    Current practices for creating a desired sound by a mechanical mechanism are irrelative design-build-test processes. It seems that very little guidance is available relating design to the sound output. The focus of this study was to identify, which parameters that affect the sound output of a click...... mechanism consisting of a toothed rack and a click arm. First several geometries of the teeth and the click arm’s head were investigated to identify the most robust and repeatable design. It was found that a flat surface in the valleys between the teeth is very beneficial in relation to repeatability...... mechanisms....

  9. Current Solid Mechanics Research

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2016-01-01

    About thirty years ago James Lighthill wrote an essay on “What is Mechanics?” With that he also included some examples of the applications of mechanics. While his emphasis was on fluid mechanics, his own research area, he also included examples from research activities in solid mechanics....

  10. Defense Mechanisms: A Bibliography.

    Science.gov (United States)

    Pedrini, D. T.; Pedrini, Bonnie C.

    This bibliography includes studies of defense mechanisms, in general, and studies of multiple mechanisms. Defense mechanisms, briefly and simply defined, are the unconscious ego defendants against unpleasure, threat, or anxiety. Sigmund Freud deserves the clinical credit for studying many mechanisms and introducing them in professional literature.…

  11. Chain propagation and termination mechanisms for polymerization of conjugated polar alkenes by [Al]-based frustrated Lewis pairs

    KAUST Repository

    He, Jianghua

    2014-11-25

    A combined experimental and theoretical study on mechanistic aspects of polymerization of conjugated polar alkenes by frustrated Lewis pairs (FLPs) based on N-heterocyclic carbene (NHC) and Al(C6F5)3 pairs is reported. This study consists of three key parts: structural characterization of active propagating intermediates, propagation kinetics, and chain-termination pathways. Zwitterionic intermediates that simulate the active propagating species in such polymerization have been generated or isolated from the FLP activation of monomers such as 2-vinylpyridine and 2-isopropenyl-2-oxazoline-one of which, IMes+-CH2C(Me)=(C3H2NO)Al(C6F5)3 - (2), has been structurally characterized. Kinetics performed on the polymerization of 2-vinylpyridine by ItBu/Al(C6F5)3 revealed that the polymerization follows a zero-order dependence on monomer concentration and a first-order dependence on initiator (ItBu) and activator [Al(C6F5)3] concentrations, indicating a bimolecular, activated monomer propagation mechanism. The Lewis pair polymerization of conjugate polar alkenes such as methacrylates is accompanied by competing chain-termination side reactions; between the two possible chain-termination pathways, the one that proceeds via intramolecular backbiting cyclization involving nucleophilic attack of the activated ester group of the growing polymer chain by the O-ester enolate active chain end to generate a six-membered lactone (δ-valerolactone)-terminated polymer chain is kinetically favored, but thermodynamically disfavored, over the pathway leading to the -ketoester-terminated chain, as revealed by computational studies.

  12. Kinetics and Mechanism of Bioactivation via S-Oxygenation of Anti-Tubercular Agent Ethionamide by Peracetic Acid.

    Science.gov (United States)

    Chipiso, Kudzanai; Logan, Isabelle E; Eskew, Matthew W; Omondi, Benard; Simoyi, Reuben H

    2016-10-11

    The kinetics and mechanism of the oxidation of the important antitubercular agent, ethionamide, ETA (2-ethylthioisonicotinamide), by peracetic acid (PAA) have been studied. It is effectively a biphasic reaction with an initial rapid first phase of the reaction which is over in about 5 s and a second slower phase of the reaction which can run up to an hour. The first phase involves the addition of a single oxygen atom to ethionamide to form the S-oxide. The second phase involves further oxidation of the S-oxide to desulfurization of ETA to give 2-ethylisonicotinamide. In contrast to the stability of most organosulfur compounds, the S-oxide of ETA is relatively stable and can be isolated. In conditions of excess ETA, the stoichiometry of the reaction was strictly 1:1: CH3CO3H + Et(C5H4)C(═S)NH2 → CH3CO2H + Et(C5H4)C(═NH)SOH. In this oxidation, it was apparent that only the sulfur center was the reactive site. Though ETA was ultimately desulfurized, only the S-oxide was stable. Electrospray ionization (ESI) spectral analysis did not detect any substantial formation of the sulfinic and sulfonic acids. This suggests that cleavage of the carbon-sulfur bond occurs at the sulfenic acid stage, resulting in the formation of an unstable sulfur species that can react further to form more stable sulfur species. In this oxidation, no sulfate formation was observed. ESI spectral analysis data showed a final sulfur species in the form of a dimeric sulfur monoxide species, H3S2O2. We derived a bimolecular rate constant for the formation of the S-oxide of (3.08 ± 0.72) × 10(2) M(-1) s(-1). Oxidation of the S-oxide further to give 2-ethylisonicotinamide gave zero order kinetics.

  13. Handbook of compliant mechanisms

    CERN Document Server

    Howell, Larry L; Olsen, Brian M

    2013-01-01

    A fully illustrated reference book giving an easy-to-understand introduction to compliant mechanisms A broad compilation of compliant mechanisms to give inspiration and guidance to those interested in using compliant mechanisms in their designs, the Handbook of Compliant Mechanisms includes graphics and descriptions of many compliant mechanisms. It comprises an extensive categorization of devices that can be used to help readers identify compliant mechanisms related to their application. It also provides chapters on the basic background in compliant mechanisms, the categories o

  14. Investigation of opening switch mechanisms based on chemically reactive plasmas

    Science.gov (United States)

    Lapatovich, W. P.; Piejak, R. B.; Proud, J. M.

    1985-11-01

    An investigation of discharge-induced chemical reactions resulting in high-density product vapors containing strongly attaching gases has been conducted to evaluate the feasibility and potential of such reactions in rapid opening plasma switches. This new concept of employing such reactions to limit and/or interrupt large currents on a microsecond time scale was studied in two element (electrodeless and electroded) devices and in three element (electroded) devices. Bimolecular and unimolecular reactions were considered. The plasma reaction between AlCl sub 3 and SiO sub 2 was studied. The electrical properties of one of the reaction products (SiCl sub 4) is reported.

  15. Mechanics and Physics of Precise Vacuum Mechanisms

    CERN Document Server

    Deulin, E. A; Panfilov, Yu V; Nevshupa, R. A

    2010-01-01

    In this book the Russian expertise in the field of the design of precise vacuum mechanics is summarized. A wide range of physical applications of mechanism design in electronic, optical-electronic, chemical, and aerospace industries is presented in a comprehensible way. Topics treated include the method of microparticles flow regulation and its determination in vacuum equipment and mechanisms of electronics; precise mechanisms of nanoscale precision based on magnetic and electric rheology; precise harmonic rotary and not-coaxial nut-screw linear motion vacuum feedthroughs with technical parameters considered the best in the world; elastically deformed vacuum motion feedthroughs without friction couples usage; the computer system of vacuum mechanisms failure predicting. This English edition incorporates a number of features which should improve its usefulness as a textbook without changing the basic organization or the general philosophy of presentation of the subject matter of the original Russian work. Exper...

  16. Exciton transport, charge extraction, and loss mechanisms in organic photovoltaics

    Science.gov (United States)

    Scully, Shawn Ryan

    Organic photovoltaics have attracted significant interest over the last decade due to their promise as clean low-cost alternatives to large-scale electric power generation such as coal-fired power, natural gas, and nuclear power. Many believe power conversion efficiency targets of 10-15% must be reached before commercialization is possible. Consequently, understanding the loss mechanisms which currently limit efficiencies to 4-5% is crucial to identify paths to reach higher efficiencies. In this work, we investigate the dominant loss mechanisms in some of the leading organic photovoltaic architectures. In the first class of architectures, which include planar heterojunctions and bulk heterojunctions with large domains, efficiencies are primarily limited by the distance photogenerated excitations (excitons) can be transported (termed the exciton diffusion length) to a heterojunction where the excitons may dissociate. We will discuss how to properly measure the exciton diffusion length focusing on the effects of optical interference and of energy transfer when using fullerenes as quenching layers and show how this explains the variety of diffusion lengths reported for the same material. After understanding that disorder and defects limit exciton diffusion lengths, we suggest some approaches to overcome this. We then extensively investigate the use of long-range resonant energy transfer to increase exciton harvesting. Using simulations and experiments as support, we discuss how energy transfer can be engineered into architectures to increase the distance excitons can be harvested. In an experimental model system, DOW Red/PTPTB, we will show how the distance excitons are harvested can be increased by almost an order of magnitude up to 27 nm from a heterojunction and give design rules and extensions of this concept for future architectures. After understanding exciton harvesting limitations we will look at other losses that are present in planar heterojunctions. One of

  17. Structure–Activity Correlations for TON, FER, and MOR in the Hydroisomerization of n-Butane

    NARCIS (Netherlands)

    Pieterse, Johannis A.Z.; Seshan, K.; Lercher, Johannes A.

    2000-01-01

    n-Butane hydroconversion was studied over (Pt-loaded) molecular sieves with TON, FER, and MOR morphology. The conversion occurs via a complex interplay of mono- and bimolecular bifunctional acid mechanism and monofunctional platinum-catalyzed hydrogenolysis. Hydroisomerization occurs bimolecularly a

  18. 507 mechanical movements mechanisms and devices

    CERN Document Server

    Brown, Henry T

    2005-01-01

    Epicyclic trains, oblique rollers, trip hammers, and lazy-tongs are among the ingenious mechanisms defined and illustrated in this intriguing collection. Spanning the first century of the Industrial Revolution, this 1868 compilation features simplified, concise illustrations of the mechanisms used in hydraulics, steam engines, pneumatics, presses, horologes, and scores of other machines.The movements of each of the 507 mechanisms are depicted in drawings on the left-hand page, and the facing page presents a brief description of the item's use and operation. Ranging from simple to intricately c

  19. Mechanical engineers' handbook, materials and engineering mechanics

    CERN Document Server

    Kutz, Myer

    2015-01-01

    Full coverage of materials and mechanical design inengineering Mechanical Engineers' Handbook, Fourth Edition provides aquick guide to specialized areas you may encounter in your work,giving you access to the basics of each and pointing you towardtrusted resources for further reading, if needed. The accessibleinformation inside offers discussions, examples, and analyses ofthe topics covered. This first volume covers materials and mechanical design, givingyou accessible and in-depth access to the most common topics you'llencounter in the discipline: carbon and alloy steels, stainlesssteels, a

  20. Mechanics rules cell biology

    Directory of Open Access Journals (Sweden)

    Wang James HC

    2010-07-01

    Full Text Available Abstract Cells in the musculoskeletal system are subjected to various mechanical forces in vivo. Years of research have shown that these mechanical forces, including tension and compression, greatly influence various cellular functions such as gene expression, cell proliferation and differentiation, and secretion of matrix proteins. Cells also use mechanotransduction mechanisms to convert mechanical signals into a cascade of cellular and molecular events. This mini-review provides an overview of cell mechanobiology to highlight the notion that mechanics, mainly in the form of mechanical forces, dictates cell behaviors in terms of both cellular mechanobiological responses and mechanotransduction.

  1. Verifiably Truthful Mechanisms

    DEFF Research Database (Denmark)

    Branzei, Simina; Procaccia, Ariel D.

    2015-01-01

    It is typically expected that if a mechanism is truthful, then the agents would, indeed, truthfully report their private information. But why would an agent believe that the mechanism is truthful? We wish to design truthful mechanisms, whose truthfulness can be verified efficiently (in...... the computational sense). Our approach involves three steps: (i) specifying the structure of mechanisms, (ii) constructing a verification algorithm, and (iii) measuring the quality of verifiably truthful mechanisms. We demonstrate this approach using a case study: approximate mechanism design without money...

  2. Mechanics of Failure Mechanisms in Structures

    CERN Document Server

    Carlson, R L; Craig, J I

    2012-01-01

    This book focuses on the mechanisms and underlying mechanics of failure in various classes of materials such as metallic, ceramic, polymeric, composite and bio-material.  Topics include tensile and compressive fracture, crack initiation and growth, fatigue and creep rupture in metallic materials, matrix cracking and delamination and environmental degradation in polymeric composites, failure of bio-materials such as prosthetic heart valves and prosthetic hip joints, failure of ceramics and ceramic matrix composites, failure of metallic matrix composites, static and dynamic buckling failure, dynamic excitations and creep buckling failure in structural systems. Chapters are devoted to failure mechanisms that are characteristic of each of the materials.  The work also provides the basic elements of fracture mechanics and studies in detail several niche topics such as the effects of toughness gradients, variable amplitude loading effects in fatigue, small fatigue cracks, and creep induced brittleness. Furthe...

  3. Mechanically induced gel formation

    NARCIS (Netherlands)

    van Herpt, Jochem T.; Stuart, Marc C. A.; Browne, Wesley R.; Feringa, Ben L.

    2013-01-01

    Mechanical triggering of gelation of an organic solution by a carbazole-based bisurea organogelator is described. Both the duration of the mechanical stimulation and the gelator concentration control the gelation process and the characteristics of the gel obtained.

  4. Welfare Undominated Groves Mechanisms

    CERN Document Server

    Apt, Krzysztof R; Guo, Mingyu; Markakis, Evangelos

    2008-01-01

    A common objective in mechanism design is to choose the outcome (for example, allocation of resources) that maximizes the sum of the agents' valuations, without introducing incentives for agents to misreport their preferences. The class of Groves mechanisms achieves this; however, these mechanisms require the agents to make payments, thereby reducing the agents' total welfare. In this paper we introduce a measure for comparing two mechanisms with respect to the final welfare they generate. This measure induces a partial order on mechanisms and we study the question of finding minimal elements with respect to this partial order. In particular, we say a non-deficit Groves mechanism is welfare undominated if there exists no other non-deficit Groves mechanism that always has a smaller or equal sum of payments. We focus on two domains: (i) auctions with multiple identical units and unit-demand bidders, and (ii) mechanisms for public project problems. In the first domain we analytically characterize all welfare und...

  5. Vibrating Wingstroke Mechanism Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposed work will develop a new method and mechanism for generating wing stroke motion of any shape and orientation. The mechanism will provide power, lift and...

  6. Mechanical restraint in psychiatry

    DEFF Research Database (Denmark)

    Bak, Jesper; Zoffmann, Vibeke; Sestoft, Dorte Maria;

    2014-01-01

    PURPOSE: To examine how potential mechanical restraint preventive factors in hospitals are associated with the frequency of mechanical restraint episodes. DESIGN AND METHODS: This study employed a retrospective association design, and linear regression was used to assess the associations. FINDING...

  7. Methods of celestial mechanics

    CERN Document Server

    Brouwer, Dirk

    2013-01-01

    Methods of Celestial Mechanics provides a comprehensive background of celestial mechanics for practical applications. Celestial mechanics is the branch of astronomy that is devoted to the motions of celestial bodies. This book is composed of 17 chapters, and begins with the concept of elliptic motion and its expansion. The subsequent chapters are devoted to other aspects of celestial mechanics, including gravity, numerical integration of orbit, stellar aberration, lunar theory, and celestial coordinates. Considerable chapters explore the principles and application of various mathematical metho

  8. Burst Mechanisms in Hydrodynamics

    CERN Document Server

    Knobloch, E

    1999-01-01

    Different mechanisms believed to be responsible for the generation of bursts in hydrodynamical systems are reviewed and a new mechanism capable of generating regular or irregular bursts of large dynamic range near threshold is described. The new mechanism is present in the interaction between oscillatory modes of odd and even parity in systems of large but finite aspect ratio, and provides an explanation for the bursting behavior observed in binary fluid convection. Additional applications of the new mechanism are proposed.

  9. Programmable mechanical metamaterials.

    Science.gov (United States)

    Florijn, Bastiaan; Coulais, Corentin; van Hecke, Martin

    2014-10-24

    We create mechanical metamaterials whose response to uniaxial compression can be programmed by lateral confinement, allowing monotonic, nonmonotonic, and hysteretic behavior. These functionalities arise from a broken rotational symmetry which causes highly nonlinear coupling of deformations along the two primary axes of these metamaterials. We introduce a soft mechanism model which captures the programmable mechanics, and outline a general design strategy for confined mechanical metamaterials. Finally, we show how inhomogeneous confinement can be explored to create multistability and giant hysteresis.

  10. Solar array deployment mechanism

    Science.gov (United States)

    Calassa, Mark C.; Kackley, Russell

    1995-05-01

    This paper describes a Solar Array Deployment Mechanism (SADM) used to deploy a rigid solar array panel on a commercial spacecraft. The application required a deployment mechanism design that was not only lightweight, but also could be produced and installed at the lowest possible cost. This paper covers design, test, and analysis of a mechanism that meets these requirements.

  11. Theme: Urban Mechanization.

    Science.gov (United States)

    Miller, Glen; And Others, Eds.

    1991-01-01

    Six theme articles discuss agricultural mechanics and its image problem, its importance, and its relevance to urban mechanization. They stress the need for agricultural mechanics and science in the urban environment for preparation for a variety of careers including landscape technology, environmental technology, energy systems management, and…

  12. Introduction to quantum mechanics

    OpenAIRE

    Villaseñor, Eduardo J. S.

    2008-01-01

    The purpose of this contribution is to give a very brief introduction to Quantum Mechanics for an audience of mathematicians. I will follow Segal's approach to Quantum Mechanics paying special attention to algebraic issues. The usual representation of Quantum Mechanics on Hilbert spaces is also discussed.

  13. Defining Game Mechanics

    DEFF Research Database (Denmark)

    Sicart (Vila), Miguel Angel

    2008-01-01

    This article defins game mechanics in relation to rules and challenges. Game mechanics are methods invoked by agents for interacting with the game world. I apply this definition to a comparative analysis of the games Rez, Every Extend Extra and Shadow of the Colossus that will show the relevance...... of a formal definition of game mechanics. Udgivelsesdato: Dec 2008...

  14. Respiratory mechanics in mechanically ventilated patients.

    Science.gov (United States)

    Hess, Dean R

    2014-11-01

    Respiratory mechanics refers to the expression of lung function through measures of pressure and flow. From these measurements, a variety of derived indices can be determined, such as volume, compliance, resistance, and work of breathing. Plateau pressure is a measure of end-inspiratory distending pressure. It has become increasingly appreciated that end-inspiratory transpulmonary pressure (stress) might be a better indicator of the potential for lung injury than plateau pressure alone. This has resulted in a resurgence of interest in the use of esophageal manometry in mechanically ventilated patients. End-expiratory transpulmonary pressure might also be useful to guide the setting of PEEP to counterbalance the collapsing effects of the chest wall. The shape of the pressure-time curve might also be useful to guide the setting of PEEP (stress index). This has focused interest in the roles of stress and strain to assess the potential for lung injury during mechanical ventilation. This paper covers both basic and advanced respiratory mechanics during mechanical ventilation.

  15. Sectoral Market Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    This paper first reviews proposals for the design of sectoral and related market mechanisms currently debated, both in the UNFCCC negotiations, and in different domestic legislative contexts. Secondly, it addresses the possible principles and technical requirements that Parties may wish to consider as the foundations for further elaboration of the mechanisms. The third issue explored herein is domestic implementation of sectoral market mechanisms by host countries, incentives to move to new market mechanisms, as well as how the transition between current and future mechanisms could be managed.

  16. Mechanical Systems, Classical Models

    CERN Document Server

    Teodorescu, Petre P

    2009-01-01

    This third volume completes the Work Mechanical Systems, Classical Models. The first two volumes dealt with particle dynamics and with discrete and continuous mechanical systems. The present volume studies analytical mechanics. Topics like Lagrangian and Hamiltonian mechanics, the Hamilton-Jacobi method, and a study of systems with separate variables are thoroughly discussed. Also included are variational principles and canonical transformations, integral invariants and exterior differential calculus, and particular attention is given to non-holonomic mechanical systems. The author explains in detail all important aspects of the science of mechanics, regarded as a natural science, and shows how they are useful in understanding important natural phenomena and solving problems of interest in applied and engineering sciences. Professor Teodorescu has spent more than fifty years as a Professor of Mechanics at the University of Bucharest and this book relies on the extensive literature on the subject as well as th...

  17. Mechanisms, Transmissions and Applications

    CERN Document Server

    Corves, Burkhard

    2012-01-01

    The first Workshop on Mechanisms, Transmissions and Applications -- MeTrApp-2011 was organized by the Mechatronics Department at the Mechanical Engineering Faculty, “Politehnica” University of Timisoara, Romania, under the patronage of the IFToMM Technical Committees Linkages and Mechanical Controls and Micromachines. The workshop brought together researchers and students who work in disciplines associated with mechanisms science and offered a great opportunity for scientists from all over the world to present their achievements, exchange innovative ideas and create solid international links, setting the trend for future developments in this important and creative field. The topics treated in this volume are mechanisms and machine design, mechanical transmissions, mechatronic and biomechanic applications, computational and experimental methods, history of mechanism and machine science and teaching methods.

  18. Mechanical Systems, Classical Models

    CERN Document Server

    Teodorescu, Petre P

    2007-01-01

    All phenomena in nature are characterized by motion; this is an essential property of matter, having infinitely many aspects. Motion can be mechanical, physical, chemical or biological, leading to various sciences of nature, mechanics being one of them. Mechanics deals with the objective laws of mechanical motion of bodies, the simplest form of motion. In the study of a science of nature mathematics plays an important role. Mechanics is the first science of nature which was expressed in terms of mathematics by considering various mathematical models, associated to phenomena of the surrounding nature. Thus, its development was influenced by the use of a strong mathematical tool; on the other hand, we must observe that mechanics also influenced the introduction and the development of many mathematical notions. In this respect, the guideline of the present book is precisely the mathematical model of mechanics. A special accent is put on the solving methodology as well as on the mathematical tools used; vectors, ...

  19. The Antikythera mechanism and the mechanical universe

    Science.gov (United States)

    Edmunds, M. G.

    2014-10-01

    How did our view of the Universe develop? By the mid-eighteenth century, a world view had developed of a system constrained by physical laws. These laws, if not entirely understood, showed regularity and could be handled mathematically to provide both explanation and prediction of celestial phenomena. Most of us have at least some hazy idea of the fundamental shift that came through the work of Copernicus, Kepler, Galileo and Newton. The idea of a 'Mechanical Universe' running rather like a clock tends to be associated with these sixteenth- and seventeenth-century pioneers. It remains a useful - and perhaps comforting - analogy. Yet, recent investigations based around the Antikythera Mechanism, an artefact from ancient Greece, reinforce a view that the 'Mechanical' conception has been around for a much longer time - indeed certainly as far back as the third century BC. The extent of mechanical design expertise existing around 100 BC as witnessed by the Antikythera Mechanism comes as a great surprise to most people. It is certainly a very ingenious device, often referred to as 'The World's First Computer' although it is really a sophisticated mechanical astronomical calculator with its functions pre-determined rather than programmable. In this review, the structure and functions of the Antikythera Mechanism are described. The astronomy, cosmology and technology inherent in the machine fit surprisingly well into the context of its contemporary Classical world. A strong claim will be made for the influence of such mechanisms on the development of astronomical and philosophical views, based on literary reference. There is evidence that the technology persisted until its spectacular and rather sudden re-appearance in Western Europe around 1300 AD. From then on it is not hard to chart a path through the astronomical clocks of the sixteenth century to Kepler's aim (expressed in a 1605 letter) to 'show that the heavenly machine is not a kind of divine, live being, but a

  20. Complications of mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Drašković Biljana

    2011-01-01

    Full Text Available Mechanical ventilation of the lungs, as an important therapeutic measure, cannot be avoided in critically ill patients. However, when machines take over some of vital functions there is always a risk of complications and accidents. Complications associated with mechanical ventilation can be divided into: 1 airway-associated complications; 2 complications in the response of patients to mechanical ventilation; and 3 complications related to the patient’s response to the device for mechanical ventilation. Complications of artificial airway may be related to intubation and extubation or the endotracheal tube. Complications of mechanical ventilation, which arise because of the patient’s response to mechanical ventilation, may primarily cause significant side effects to the lungs. During the last two decades it was concluded that mechanical ventilation can worsen or cause acute lung injury. Mechanical ventilation may increase the alveolar/capillary permeability by overdistension of the lungs (volutrauma, it can exacerbate lung damage due to the recruitment/derecruitment of collapsed alveoli (atelectrauma and may cause subtle damages due to the activation of inflammatory processes (biotrauma. Complications caused by mechanical ventilation, beside those involving the lungs, can also have significant effects on other organs and organic systems, and can be a significant factor contributing to the increase of morbidity and mortality in critically ill of mechanically ventilated patients. Complications are fortunately rare and do not occur in every patient, but due to their seriousness and severity they require extensive knowledge, experience and responsibility by health-care workers.

  1. Auto Mechanics: Auto Mechanic Service Specialist (Lubrication).

    Science.gov (United States)

    Hoover, Virgil

    The unit of individualized learning activities is designed to provide training in the job skill, lubrication, for the prospective auto mechanic service specialist. The materials in the unit are divided into two sections. The developmental, or preliminary phase, for use by the instructor, includes brief descriptions of the job and of the student…

  2. Entropy in bimolecular simulations: A comprehensive review of atomic fluctuations-based methods.

    Science.gov (United States)

    Kassem, Summer; Ahmed, Marawan; El-Sheikh, Salah; Barakat, Khaled H

    2015-11-01

    Entropy of binding constitutes a major, and in many cases a detrimental, component of the binding affinity in biomolecular interactions. While the enthalpic part of the binding free energy is easier to calculate, estimating the entropy of binding is further more complicated. A precise evaluation of entropy requires a comprehensive exploration of the complete phase space of the interacting entities. As this task is extremely hard to accomplish in the context of conventional molecular simulations, calculating entropy has involved many approximations. Most of these golden standard methods focused on developing a reliable estimation of the conformational part of the entropy. Here, we review these methods with a particular emphasis on the different techniques that extract entropy from atomic fluctuations. The theoretical formalisms behind each method is explained highlighting its strengths as well as its limitations, followed by a description of a number of case studies for each method. We hope that this brief, yet comprehensive, review provides a useful tool to understand these methods and realize the practical issues that may arise in such calculations.

  3. Heterologous aggregates promote de novo prion appearance via more than one mechanism.

    Directory of Open Access Journals (Sweden)

    Fatih Arslan

    2015-01-01

    Full Text Available Prions are self-perpetuating conformational variants of particular proteins. In yeast, prions cause heritable phenotypic traits. Most known yeast prions contain a glutamine (Q/asparagine (N-rich region in their prion domains. [PSI+], the prion form of Sup35, appears de novo at dramatically enhanced rates following transient overproduction of Sup35 in the presence of [PIN+], the prion form of Rnq1. Here, we establish the temporal de novo appearance of Sup35 aggregates during such overexpression in relation to other cellular proteins. Fluorescently-labeled Sup35 initially forms one or a few dots when overexpressed in [PIN+] cells. One of the dots is perivacuolar, colocalizes with the aggregated Rnq1 dot and grows into peripheral rings/lines, some of which also colocalize with Rnq1. Sup35 dots that are not near the vacuole do not always colocalize with Rnq1 and disappear by the time rings start to grow. Bimolecular fluorescence complementation failed to detect any interaction between Sup35-VN and Rnq1-VC in [PSI+][PIN+] cells. In contrast, all Sup35 aggregates, whether newly induced or in established [PSI+], completely colocalize with the molecular chaperones Hsp104, Sis1, Ssa1 and eukaryotic release factor Sup45. In the absence of [PIN+], overexpressed aggregating proteins such as the Q/N-rich Pin4C or the non-Q/N-rich Mod5 can also promote the de novo appearance of [PSI+]. Similar to Rnq1, overexpressed Pin4C transiently colocalizes with newly appearing Sup35 aggregates. However, no interaction was detected between Mod5 and Sup35 during [PSI+] induction in the absence of [PIN+]. While the colocalization of Sup35 and aggregates of Rnq1 or Pin4C are consistent with the model that the heterologous aggregates cross-seed the de novo appearance of [PSI+], the lack of interaction between Mod5 and Sup35 leaves open the possibility of other mechanisms. We also show that Hsp104 is required in the de novo appearance of [PSI+] aggregates in a [PIN

  4. Nonholonomic mechanics and control

    CERN Document Server

    Murray, RM

    2015-01-01

    This book explores some of the connections between control theory and geometric mechanics; that is, control theory is linked with a geometric view of classical mechanics in both its Lagrangian and Hamiltonian formulations and in particular with the theory of mechanical systems subject to motion constraints. The synthesis of the topic is appropriate as there is a particularly rich connection between mechanics and nonlinear control theory. The book provides a unified treatment of nonlinear control theory and constrained mechanical systems and illustrates the elegant mathematics behind many simple, interesting, and useful mechanical examples. It is intended for graduate students who wish to learn this subject and researchers in the area who want to enhance their techniques. The book contains sections focusing on physical examples and elementary terms, as well as theoretical sections that use sophisticated analysis and geometry. The first four chapters offer preliminaries and background information, while the...

  5. Cell mechanics: a dialogue

    Science.gov (United States)

    Tao, Jiaxiang; Li, Yizeng; Vig, Dhruv K.; Sun, Sean X.

    2017-03-01

    Under the microscope, eukaryotic animal cells can adopt a variety of different shapes and sizes. These cells also move and deform, and the physical mechanisms driving these movements and shape changes are important in fundamental cell biology, tissue mechanics, as well as disease biology. This article reviews some of the basic mechanical concepts in cells, emphasizing continuum mechanics description of cytoskeletal networks and hydrodynamic flows across the cell membrane. We discuss how cells can generate movement and shape changes by controlling mass fluxes at the cell boundary. These mass fluxes can come from polymerization/depolymerization of actin cytoskeleton, as well as osmotic and hydraulic pressure-driven flow of water across the cell membrane. By combining hydraulic pressure control with force balance conditions at the cell surface, we discuss a quantitative mechanism of cell shape and volume control. The broad consequences of this model on cell mechanosensation and tissue mechanics are outlined.

  6. Quantum mechanics in chemistry

    CERN Document Server

    Schatz, George C

    2002-01-01

    Intended for graduate and advanced undergraduate students, this text explores quantum mechanical techniques from the viewpoint of chemistry and materials science. Dynamics, symmetry, and formalism are emphasized. An initial review of basic concepts from introductory quantum mechanics is followed by chapters examining symmetry, rotations, and angular momentum addition. Chapter 4 introduces the basic formalism of time-dependent quantum mechanics, emphasizing time-dependent perturbation theory and Fermi's golden rule. Chapter 5 sees this formalism applied to the interaction of radiation and matt

  7. Equilibrium statistical mechanics

    CERN Document Server

    Jackson, E Atlee

    2000-01-01

    Ideal as an elementary introduction to equilibrium statistical mechanics, this volume covers both classical and quantum methodology for open and closed systems. Introductory chapters familiarize readers with probability and microscopic models of systems, while additional chapters describe the general derivation of the fundamental statistical mechanics relationships. The final chapter contains 16 sections, each dealing with a different application, ordered according to complexity, from classical through degenerate quantum statistical mechanics. Key features include an elementary introduction t

  8. On Noncommutative Classical Mechanics

    CERN Document Server

    Djemai, A E F

    2003-01-01

    In this work, I investigate the noncommutative Poisson algebra of classical observables corresponding to a proposed general Noncommutative Quantum Mechanics, \\cite{1}. I treat some classical systems with various potentials and some Physical interpretations are given concerning the presence of noncommutativity at large scales (Celeste Mechanics) directly tied to the one present at small scales (Quantum Mechanics) and its possible relation with UV/IR mixing.

  9. Mechanics and uncertainty

    CERN Document Server

    Lemaire, Maurice

    2014-01-01

    Science is a quest for certainty, but lack of certainty is the driving force behind all of its endeavors. This book, specifically, examines the uncertainty of technological and industrial science. Uncertainty and Mechanics studies the concepts of mechanical design in an uncertain setting and explains engineering techniques for inventing cost-effective products. Though it references practical applications, this is a book about ideas and potential advances in mechanical science.

  10. Lectures on statistical mechanics

    CERN Document Server

    Bowler, M G

    1982-01-01

    Anyone dissatisfied with the almost ritual dullness of many 'standard' texts in statistical mechanics will be grateful for the lucid explanation and generally reassuring tone. Aimed at securing firm foundations for equilibrium statistical mechanics, topics of great subtlety are presented transparently and enthusiastically. Very little mathematical preparation is required beyond elementary calculus and prerequisites in physics are limited to some elementary classical thermodynamics. Suitable as a basis for a first course in statistical mechanics, the book is an ideal supplement to more convent

  11. Mechanical and Aerospace Engineering

    OpenAIRE

    Millsaps, Knox T.; Gordis, J. H.; Brophy, C. M.; Stephens, Sandra

    2008-01-01

    This brochure explains the Mechanical and Aerospace Engineering program at the Naval Postgraduate School. Sections include: Advancing your career, student research, degree programs, special programs, research and distance learning programs. The Mechanical and Aerospace Engineering (MAE) Department, the founding department of the Naval Postgraduate School in 1909, offers a wide range of graduate degree programs including M.S. and Ph.D., in either Mechanical or Astronautical En...

  12. Equilibrium statistical mechanics

    CERN Document Server

    Mayer, J E

    1968-01-01

    The International Encyclopedia of Physical Chemistry and Chemical Physics, Volume 1: Equilibrium Statistical Mechanics covers the fundamental principles and the development of theoretical aspects of equilibrium statistical mechanics. Statistical mechanical is the study of the connection between the macroscopic behavior of bulk matter and the microscopic properties of its constituent atoms and molecules. This book contains eight chapters, and begins with a presentation of the master equation used for the calculation of the fundamental thermodynamic functions. The succeeding chapters highlight t

  13. Testing Nonassociative Quantum Mechanics.

    Science.gov (United States)

    Bojowald, Martin; Brahma, Suddhasattwa; Büyükçam, Umut

    2015-11-27

    The familiar concepts of state vectors and operators in quantum mechanics rely on associative products of observables. However, these notions do not apply to some exotic systems such as magnetic monopoles, which have long been known to lead to nonassociative algebras. Their quantum physics has remained obscure. This Letter presents the first derivation of potentially testable physical results in nonassociative quantum mechanics, based on effective potentials. They imply new effects which cannot be mimicked in usual quantum mechanics with standard magnetic fields.

  14. Mechanically reinforced glass beams

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes

    2007-01-01

    to breakage without any warning or ductility, which can be catastrophic if no precautions are taken. One aspect of this issue is treated here by looking at the possibility of mechanically reinforcing glass beams in order to obtain ductile failure for such a structural component. A mechanically reinforced...... the mechanical behavior of the beam is explained. Finally, some design criterions for reinforced glass beams are discussed....

  15. Fuzzy clustering of mechanisms

    Indian Academy of Sciences (India)

    Amitabha Ghosh; Dilip Kumar Pratihar; M V V Amarnath; Guenter Dittrich; Jorg Mueller

    2012-10-01

    During the course of development of Mechanical Engineering, a large number of mechanisms (that is, linkages to perform various types of tasks) have been conceived and developed. Quite a few atlases and catalogues were prepared by the designers of machines and mechanical systems. However, often it is felt that a clustering technique for handling the list of large number of mechanisms can be very useful,if it is developed based on a scientific principle. In this paper, it has been shown that the concept of fuzzy sets can be conveniently used for this purpose, if an adequate number of properly chosen attributes (also called characteristics) are identified. Using two clustering techniques, the mechanisms have been classified in the present work and in future, it may be extended to develop an expert system, which can automate type synthesis phase of mechanical design. To the best of the authors’ knowledge, this type of clustering of mechanisms has not been attempted before. Thus, this is the first attempt to cluster the mechanisms based on some quantitative measures. It may help the engineers to carry out type synthesis of the mechanisms.

  16. Mechanisms for space applications

    Science.gov (United States)

    Meftah, M.; Irbah, A.; Le Letty, R.; Barré, M.; Pasquarella, S.; Bokaie, M.; Bataille, A.; Poiet, G.

    2012-06-01

    All space instruments contain mechanisms or moving mechanical assemblies that must move (sliding, rolling, rotating, or spinning) and their successful operation is usually mission-critical. Generally, mechanisms are not redundant and therefore represent potential single point failure modes. Several space missions have suffered anomalies or failures due to problems in applying space mechanisms technology. Mechanisms require a specific qualification through a dedicated test campaign. This paper covers the design, development, testing, production, and in-flight experience of the PICARD/SODISM mechanisms. PICARD is a space mission dedicated to the study of the Sun. The PICARD Satellite was successfully launched, on June 15, 2010 on a DNEPR launcher from Dombarovskiy Cosmodrome, near Yasny (Russia). SODISM (SOlar Diameter Imager and Surface Mapper) is a 11 cm Ritchey-Chretien imaging telescope, taking solar images at five wavelengths. SODISM uses several mechanisms (a system to unlock the door at the entrance of the instrument, a system to open/closed the door using a stepper motor, two filters wheels using a stepper motor, and a mechanical shutter). For the fine pointing, SODISM uses three piezoelectric devices acting on the primary mirror of the telescope. The success of the mission depends on the robustness of the mechanisms used and their life.

  17. Carboxylation of sodium 2-naphthoxide. Reinvestigation of the mechanism by means of a hybrid meta density functional theory method

    Directory of Open Access Journals (Sweden)

    Đurović Igor B.

    2015-01-01

    Full Text Available Aromatic hydroxy acids, the compounds of large industrial importance, can be prepared in the Kolbe-Schmitt reaction, i.e. a carboxylation reaction of alkali metal phenoxides (MOPh and naphthoxides (MONaph. On the basis of the experimental results two contradictory reaction mechanisms have been proposed: the one of direct carboxylation, and the other involving initial formation of the MOPh-CO2 or MONaph-CO2 complex. Previous theoretical investigations of the carboxylation reaction of sodium 2-naphthoxide, performed by means of the B3LYP method, confirmed the initial formation of the NaONaph-CO2 complex, and showed that the carbon of the CO2 moiety performs an electrophilic attack at C1 of the ring, leading to the formation of sodium 2-hydroxy-1-naphthoate (E1. Surprisingly, transition states for possible electrophilic attacks at C3 and C6 were not revealed, and the formation of other two products (E3 and E6 was explained by a number of consecutive rearrangements. In addition, this mechanism includes a reaction step with rather high activation energy. Since more sophisticated functionals are today available, the aim of this work is to reinvestigate the mechanism of the Kolbe-Schmitt reaction of NaONaph in all three positions (1, 3, and 6. Our investigations with the M062X method demonstrated that CO2 and NaONaph can spontaneously build two complexes: B (the one previously reported and C. While B cannot be further transformed to yield the reaction products, the CO2 moiety in C takes perfect position for electrophilic attacks at all three sites of the ring. These attacks are realized via the transition states TS1, which lead to the formation of the new C-C bonds, and corresponding intermediates D. In the next, bimolecular reaction step two D intermediates exchange the protons adjacent to the CO2 groups. These intermolecular reaction steps require significantly lower activation energies in comparison to the intramolecular proton shift from C to O

  18. Problems in quantum mechanics

    CERN Document Server

    Goldman, Iosif Ilich; Geilikman, B T

    2006-01-01

    This challenging book contains a comprehensive collection of problems in nonrelativistic quantum mechanics of varying degrees of difficulty. It features answers and completely worked-out solutions to each problem. Geared toward advanced undergraduates and graduate students, it provides an ideal adjunct to any textbook in quantum mechanics.

  19. Goryachkin's agricultural mechanics

    Science.gov (United States)

    Chinenova, Vera

    2016-03-01

    The paper contributes to the development of applied mechanics by establishing a new discipline, namely, agricultural mechanics by academician Vasilii Prohorovich Goryachkin (1868-1935) who was an apprentice of Nikolay Yegorovich Zhukovsky and a graduate of the Moscow University (current known as Moscow State University) and the Imperial Higher Technical School.

  20. Shooting mechanisms in nature

    NARCIS (Netherlands)

    Sakes, Aimée; Wiel, van der Marleen; Henselmans, Paul W.J.; Leeuwen, van Johan L.; Dodou, Dimitra; Breedveld, Paul

    2016-01-01

    Background In nature, shooting mechanisms are used for a variety of purposes, including prey capture, defense, and reproduction. This review offers insight into the working principles of shooting mechanisms in fungi, plants, and animals in the light of the specific functional demands that these m

  1. Mechanical ventilation in children.

    Science.gov (United States)

    Kendirli, Tanil; Kavaz, Asli; Yalaki, Zahide; Oztürk Hişmi, Burcu; Derelli, Emel; Ince, Erdal

    2006-01-01

    Mechanical ventilation can be lifesaving, but > 50% of complications in conditions that require intensive care are related to ventilatory support, particularly if it is prolonged. We retrospectively evaluated the medical records of patients who had mechanical ventilation in the Pediatric Intensive Care Unit (PICU) during a follow-up period between January 2002-May 2005. Medical records of 407 patients were reviewed. Ninety-one patients (22.3%) were treated with mechanical ventilation. Ages of all patients were between 1-180 (median: 8) months. The mechanical ventilation time was 18.8 +/- 14.1 days. Indication of mechanical ventilation could be divided into four groups as respiratory failure (64.8%), cardiovascular failure (19.7%), central nervous system disease (9.8%) and safety airway (5.4%). Tracheostomy was performed in four patients. The complication ratio of mechanically ventilated children was 42.8%, and diversity of complications was as follows: 26.3% atelectasia, 17.5% ventilator-associated pneumonia, 13.1% pneumothorax, 5.4% bleeding, 4.3% tracheal edema, and 2.1% chronic lung disease. The mortality rate of mechanically ventilated patients was 58.3%, but the overall mortality rate in the PICU was 12.2%. In conclusion, there are few published epidemiological data on the follow-up results and mortality in infants and children who are mechanically ventilated.

  2. Mecanica Clasica (Classical Mechanics)

    OpenAIRE

    Rosu, H. C.

    1999-01-01

    First Internet graduate course on Classical Mechanics in Spanish (Castellano). This is about 80% of the material I covered during the January-June 1999 semester at IFUG in the Mexican city of Leon. English and Romanian versions are in (slow) progress and hopefully will be arXived. For a similar course on Quantum Mechanics, see physics/9808031

  3. Mecanica Clasica (Classical Mechanics)

    CERN Document Server

    Rosu, H C

    1999-01-01

    First Internet undergraduate course on Classical Mechanics in Spanish (Castellano). This is about 80% of the material I covered during the January-June 1999 semester at IFUG in the Mexican city of Leon. English and Romanian versions are in (slow) progress and hopefully will be arXived. For a similar course on Quantum Mechanics, see physics/9808031

  4. Infection and inflammatory mechanisms

    NARCIS (Netherlands)

    Van Dyke, Thomas E.; van Winkelhoff, Arie Jan

    2013-01-01

    This introductory article examines the potential mechanisms that may play a role in the associations between periodontitis and the systemic conditions being considered in the EFP/AAP Workshop in Segovia, Spain. Three basic mechanisms have been postulated to play a role in these interactions; metasta

  5. Membrane quantum mechanics

    Directory of Open Access Journals (Sweden)

    Tadashi Okazaki

    2015-01-01

    Full Text Available We consider the multiple M2-branes wrapped on a compact Riemann surface and study the arising quantum mechanics by taking the limit where the size of the Riemann surface goes to zero. The IR quantum mechanical models resulting from the BLG-model and the ABJM-model compactified on a torus are N=16 and N=12 superconformal gauged quantum mechanics. After integrating out the auxiliary gauge fields we find OSp(16|2 and SU(1,1|6 quantum mechanics from the reduced systems. The curved Riemann surface is taken as a holomorphic curve in a Calabi–Yau space to preserve supersymmetry and we present a prescription of the topological twisting. We find the N=8 superconformal gauged quantum mechanics that may describe the motion of two wrapped M2-branes in a K3 surface.

  6. Quantum mechanics for pedestrians

    CERN Document Server

    Pade, Jochen

    2014-01-01

    This book provides an introduction into the fundamentals of non-relativistic quantum mechanics. In Part 1, the essential principles are developed. Applications and extensions of the formalism can be found in Part 2. The book includes not only material that is presented in traditional textbooks on quantum mechanics, but also discusses in detail current issues such as interaction-free quantum measurements, neutrino oscillations, various topics in the field of quantum information as well as fundamental problems and epistemological questions, such as the measurement problem, entanglement, Bell's inequality, decoherence, and the realism debate. A chapter on current interpretations of quantum mechanics concludes the book. To develop quickly and clearly the main principles of quantum mechanics and its mathematical formulation, there is a systematic change between wave mechanics and algebraic representation in the first chapters. The required mathematical tools are introduced step by step. Moreover, the appendix coll...

  7. Mechanics an intensive course

    CERN Document Server

    Chaichian, Masud; Tureanu, Anca

    2012-01-01

    Mechanics is one of the oldest and at the same time newest disciplines, in the sense that there are methods and principles developed first in mechanics but now widely used in almost all branches of physics: electrodynamics, quantum mechanics, classical and quantum field theory, special and general theory of relativity, etc. More than that, there are some formalisms like Lagrangian and Hamiltonian approaches, which represent the key stone for the development of the above-mentioned disciplines. During the last 20-25 years, classical mechanics has undergone an important revival associated with the progress in non-linear dynamics, applications of Noether’s theorem and the extension of variational principles in various interdisciplinary sciences (for instance, magnetofluid dynamics). Thus, there ought to exist a book concerned with the applied analytical formalism, first developed in the frame of theoretical mechanics, which has proved to be one of the most efficient tools of investigation in the entire arena of...

  8. Quantum mechanics for mathematicians

    CERN Document Server

    Takhtajan, Leon A

    2008-01-01

    This book provides a comprehensive treatment of quantum mechanics from a mathematics perspective and is accessible to mathematicians starting with second-year graduate students. It addition to traditional topics, like classical mechanics, mathematical foundations of quantum mechanics, quantization, and the Schrodinger equation, this book gives a mathematical treatment of systems of identical particles with spin, and it introduces the reader to functional methods in quantum mechanics. This includes the Feynman path integral approach to quantum mechanics, integration in functional spaces, the relation between Feynman and Wiener integrals, Gaussian integration and regularized determinants of differential operators, fermion systems and integration over anticommuting (Grassmann) variables, supersymmetry and localization in loop spaces, and supersymmetric derivation of the Atiyah-Singer formula for the index of the Dirac operator. Prior to this book, mathematicians could find these topics only in physics textbooks ...

  9. Advanced Visual Quantum Mechanics

    CERN Document Server

    Thaller, Bernd

    2005-01-01

    Advanced Visual Quantum Mechanics is a systematic effort to investigate and to teach quantum mechanics with the aid of computer-generated animations. It is a self-contained textbook that combines selected topics from atomic physics (spherical symmetry, the hydrogen atom, and particles with spin) with an introduction to quantum information theory (qubits, EPR paradox, teleportation, quantum computers). It explores relativistic quantum mechanics and the strange behavior of Dirac equation solutions. A series of appendices covers important topics from perturbation and scattering theory. The book places an emphasis on ideas and concepts, with a fair to moderate amount of mathematical rigor. Though this book stands alone, it can also be paired with Thaller Visual Quantum Mechanics to form a comprehensive course in quantum mechanics. The software for the first book earned the European Academic Software Award 2000 for outstanding innovation in its field.

  10. Engineering quantum mechanics

    CERN Document Server

    Ahn, Doyeol

    2011-01-01

    A clear introduction to quantum mechanics concepts Quantum mechanics has become an essential tool for modern engineering, particularly due to the recent developments in quantum computing as well as the rapid progress in optoelectronic devices. Engineering Quantum Mechanics explains the fundamentals of this exciting field, providing broad coverage of both traditional areas such as semiconductor and laser physics as well as relatively new yet fast-growing areas such as quantum computation and quantum information technology. The book begins with basic quantum mechanics, reviewing measurements and probability, Dirac formulation, the uncertainty principle, harmonic oscillator, angular momentum eigenstates, and perturbation theory. Then, quantum statistical mechanics is explored, from second quantization and density operators to coherent and squeezed states, coherent interactions between atoms and fields, and the Jaynes-Cummings model. From there, the book moves into elementary and modern applications, discussing s...

  11. Testing the Palma-Clary Reduced Dimensionality Model Using Classical Mechanics on the CH4 + H → CH3 + H2 Reaction.

    Science.gov (United States)

    Vikár, Anna; Nagy, Tibor; Lendvay, György

    2016-07-14

    Application of exact quantum scattering methods in theoretical reaction dynamics of bimolecular reactions is limited by the complexity of the equations of nuclear motion to be solved. Simplification is often achieved by reducing the number of degrees of freedom to be explicitly handled by freezing the less important spectator modes. The reaction cross sections obtained in reduced-dimensionality (RD) quantum scattering methods can be used in the calculation of rate coefficients, but their physical meaning is limited. The accurate test of the performance of a reduced-dimensionality method would be a comparison of the RD cross sections with those obtained in accurate full-dimensional (FD) calculations, which is not feasible because of the lack of complete full-dimensional results. However, classical mechanics allows one to perform reaction dynamics calculations using both the RD and the FD model. In this paper, an RD versus FD comparison is made for the 8-dimensional Palma-Clary model on the example of four isotopologs of the CH4 + H → CH3 + H2 reaction, which has 12 internal dimensions. In the Palma-Clary model, the only restriction is that the methyl group is confined to maintain C3v symmetry. Both RD and FD opacity and excitation functions as well as differential cross sections were calculated using the quasiclassical trajectory method. The initial reactant separation has been handled according to our one-period averaging method [ Nagy et al. J. Chem. Phys. 2016, 144, 014104 ]. The RD and FD excitation functions were found to be close to each other for some isotopologs, but in general, the RD reactivity parameters are lower than the FD reactivity parameters beyond statistical error, and for one of the isotopologs, the deviation is significant. This indicates that the goodness of RD cross sections cannot be taken for granted.

  12. The orbital mechanics of flight mechanics

    Science.gov (United States)

    Dunning, R. S.

    1973-01-01

    A reference handbook on modern dynamic orbit theory is presented. Starting from the most basic inverse-square law, the law of gravity for a sphere is developed, and the motion of point masses under the influence of a sphere is considered. The reentry theory and the orbital theory are discussed along with the relative motion between two bodies in orbit about the same planet. Relative-motion equations, rectangular coordinates, and the mechanics of simple rigid bodies under the influence of a gravity gradient field are also discussed.

  13. Mechanics, Waves and Thermodynamics

    Science.gov (United States)

    Ranjan Jain, Sudhir

    2016-05-01

    Figures; Preface; Acknowledgement; 1. Energy, mass, momentum; 2. Kinematics, Newton's laws of motion; 3. Circular motion; 4. The principle of least action; 5. Work and energy; 6. Mechanics of a system of particles; 7. Friction; 8. Impulse and collisions; 9. Central forces; 10. Dimensional analysis; 11. Oscillations; 12. Waves; 13. Sound of music; 14. Fluid mechanics; 15. Water waves; 16. The kinetic theory of gases; 17. Concepts and laws of thermodynamics; 18. Some applications of thermodynamics; 19. Basic ideas of statistical mechanics; Bibliography; Index.

  14. Is quantum mechanics exact?

    Energy Technology Data Exchange (ETDEWEB)

    Kapustin, Anton [California Institute of Technology, Pasadena, California 91125 (United States)

    2013-06-15

    We formulate physically motivated axioms for a physical theory which for systems with a finite number of degrees of freedom uniquely lead to quantum mechanics as the only nontrivial consistent theory. Complex numbers and the existence of the Planck constant common to all systems arise naturally in this approach. The axioms are divided into two groups covering kinematics and basic measurement theory, respectively. We show that even if the second group of axioms is dropped, there are no deformations of quantum mechanics which preserve the kinematic axioms. Thus, any theory going beyond quantum mechanics must represent a radical departure from the usual a priori assumptions about the laws of nature.

  15. Mechanism of Gravity Impulse

    Institute of Scientific and Technical Information of China (English)

    WU Ning

    2006-01-01

    It is well known that energy-momentum is the source of gravitational field. For a long time, it is generally believed that only stars with huge masses can generate strong gravitational field. Based on the unified theory of gravitational interactions and electromagnetic interactions, a new mechanism of the generation of gravitational field is studied. According to this mechanism, in some special conditions, electromagnetic energy can be directly converted into gravitational energy, and strong gravitational field can be generated without massive stars. Gravity impulse found in experiments is generated by this mechanism.

  16. Analytical elements of mechanics

    CERN Document Server

    Kane, Thomas R

    2013-01-01

    Analytical Elements of Mechanics, Volume 1, is the first of two volumes intended for use in courses in classical mechanics. The books aim to provide students and teachers with a text consistent in content and format with the author's ideas regarding the subject matter and teaching of mechanics, and to disseminate these ideas. The book opens with a detailed exposition of vector algebra, and no prior knowledge of this subject is required. This is followed by a chapter on the topic of mass centers, which is presented as a logical extension of concepts introduced in connection with centroids. A

  17. Notes on continuum mechanics

    CERN Document Server

    Chaves, Eduardo W V

    2013-01-01

    This publication is aimed at students, teachers, and researchers of Continuum Mechanics and focused extensively on stating and developing Initial Boundary Value equations used to solve physical problems. With respect to notation, the tensorial, indicial and Voigt notations have been used indiscriminately.   The book is divided into twelve chapters with the following topics: Tensors, Continuum Kinematics, Stress, The Objectivity of Tensors, The Fundamental Equations of Continuum Mechanics, An Introduction to Constitutive Equations, Linear Elasticity, Hyperelasticity, Plasticity (small and large deformations), Thermoelasticity (small and large deformations), Damage Mechanics (small and large deformations), and An Introduction to Fluids. Moreover, the text is supplemented with over 280 figures, over 100 solved problems, and 130 references.

  18. Applications in solid mechanics

    DEFF Research Database (Denmark)

    Ølgaard, Kristian Breum; Wells, Garth N.

    2012-01-01

    Problems in solid mechanics constitute perhaps the largest field of application of finite element methods. The vast majority of solid mechanics problems involve the standard momentum balance equation, posed in a Lagrangian setting, with different models distinguished by the choice of nonlinear...... or linearized kinematics, and the constitutive model for determining the stress. For some common models, the constitutive relationships are rather complex. This chapter addresses a number of canonical solid mechanics models in the context of automated modeling, and focuses on some pertinent issues that arise...

  19. Mechanics of Generalized Continua

    CERN Document Server

    Maugin, Gerard A

    2010-01-01

    In their 1909 publication "Theorie des corps deformables", Eugene and Francois Cosserat made a historic contribution to materials science by establishing the fundamental principles of the mechanics of generalized continua. The chapters collected in this volume showcase the many areas of continuum mechanics that grew out of the foundational work of the Cosserat brothers. The included contributions provide a detailed survey of the most recent theoretical developments in the field of generalized continuum mechanics. The diverse topics covered include: the properties of Cosserat media, m

  20. Rotary mechanical latch

    Science.gov (United States)

    Spletzer, Barry L.; Martinez, Michael A.; Marron, Lisa C.

    2012-11-13

    A rotary mechanical latch for positive latching and unlatching of a rotary device with a latchable rotating assembly having a latching gear that can be driven to latched and unlatched states by a drive mechanism such as an electric motor. A cam arm affixed to the latching gear interfaces with leading and trailing latch cams affixed to a flange within the drive mechanism. The interaction of the cam arm with leading and trailing latch cams prevents rotation of the rotating assembly by external forces such as those due to vibration or tampering.

  1. Mechanisms of hypoxemia

    Science.gov (United States)

    Sarkar, Malay; Niranjan, N; Banyal, PK

    2017-01-01

    Oxygen is an essential element for life and without oxygen humans can survive for few minutes only. There should be a balance between oxygen demand and delivery in order to maintain homeostasis within the body. The two main organ systems responsible for oxygen delivery in the body and maintaining homeostasis are respiratory and cardiovascular system. Abnormal function of any of these two would lead to the development of hypoxemia and its detrimental consequences. There are various mechanisms of hypoxemia but ventilation/perfusion mismatch is the most common underlying mechanism of hypoxemia. The present review will focus on definition, various causes, mechanisms, and approach of hypoxemia in human. PMID:28144061

  2. Lectures on quantum mechanics

    CERN Document Server

    Dirac, Paul A M

    2001-01-01

    The author of this concise, brilliant series of lectures on mathematical methods in quantum mechanics was one of the shining intellects in the field, winning a Nobel prize in 1933 for his pioneering work in the quantum mechanics of the atom. Beyond that, he developed the transformation theory of quantum mechanics (which made it possible to calculate the statistical distribution of certain variables), was one of the major authors of the quantum theory of radiation, codiscovered the Fermi-Dirac statistics, and predicted the existence of the positron.The four lectures in this book were delivered

  3. Mechanical engineers data handbook

    CERN Document Server

    Carvill, James

    1994-01-01

    This text provides the student and professional mechanical engineer with a reference text of an essentially practical nature. It is uncluttered by text, and extensive use of illustrations and tables provide quick and clear access to information. It alsoincludes examples of detailed calculations on many of the applications of technology used by mechanical and production engineers, draughtsmen and engineering designers.Although mainly intended for those studying and practising mechanical engineering, a glance at the contents will show that it is also useful to those in related br

  4. Fluid and particle mechanics

    CERN Document Server

    Michell, S J

    2013-01-01

    Fluid and Particle Mechanics provides information pertinent to hydraulics or fluid mechanics. This book discusses the properties and behavior of liquids and gases in motion and at rest. Organized into nine chapters, this book begins with an overview of the science of fluid mechanics that is subdivided accordingly into two main branches, namely, fluid statics and fluid dynamics. This text then examines the flowmeter devices used for the measurement of flow of liquids and gases. Other chapters consider the principle of resistance in open channel flow, which is based on improper application of th

  5. Facing quantum mechanical reality.

    Science.gov (United States)

    Rohrlich, F

    1983-09-23

    Two recent precision experiments provide conclusive evidence against any local hidden variables theory and in favor of standard quantum mechanics. Therefore the epistemology and the ontology of quantum mechanics must now be taken more seriously than ever before. The consequences of the standard interpretation of quantum mechanics are summarized in nontechnical language. The implications of the finiteness of Planck's constant (h > 0) for the quantum world are as strange as the implications of the finiteness of the speed of light (c < infinity for space and time in relativity theory. Both lead to realities beyond our common experience that cannot be rejected.

  6. Mechanics classical and quantum

    CERN Document Server

    Taylor, T T

    2015-01-01

    Mechanics: Classical and Quantum explains the principles of quantum mechanics via the medium of analytical mechanics. The book describes Schrodinger's formulation, the Hamilton-Jacobi equation, and the Lagrangian formulation. The author discusses the Harmonic Oscillator, the generalized coordinates, velocities, as well as the application of the Lagrangian formulation to systems that are partially or entirely electromagnetic in character under certain conditions. The book examines waves on a string under tension, the isothermal cavity radiation, and the Rayleigh-Jeans result pertaining to the e

  7. Mechanical design engineering handbook

    CERN Document Server

    Childs, Peter R N

    2013-01-01

    Mechanical Design Engineering Handbook is a straight-talking and forward-thinking reference covering the design, specification, selection, use and integration of machine elements fundamental to a wide range of engineering applications. Develop or refresh your mechanical design skills in the areas of bearings, shafts, gears, seals, belts and chains, clutches and brakes, springs, fasteners, pneumatics and hydraulics, amongst other core mechanical elements, and dip in for principles, data and calculations as needed to inform and evaluate your on-the-job decisions. Covering the full spectrum

  8. The Mechanisms of Involuntary Attention

    Science.gov (United States)

    Prinzmetal, William; Ha, Ruby; Khani, Aniss

    2010-01-01

    We tested 3 mechanisms of involuntary attention: (1) a perceptual enhancement mechanism, (2) a response-decision mechanism, and (3) a serial-search mechanism. Experiment 1 used a response deadline technique to compare the perceptual enhancement and the decision mechanisms and found evidence consistent with the decision mechanism. Experiment 2 used…

  9. ELECTROMAGNETIC RELEASE MECHANISM

    Science.gov (United States)

    Michelson, C.

    1960-09-13

    An electromagnetic release mechanism is offered that may be used, for example, for supporting a safety rod for a nuclear reactor. The release mechanism is designed to have a large excess holding force and a rapid, uniform, and dependable release. The fast release is accomplished by providing the electromagnet with slotttd polts separated by an insulating potting resin, and by constructing the poles with a ferro-nickel alloy. The combination of these two features materially reduces the eddy current power density whenever the magnetic field changes during a release operation. In addition to these features, the design of the armature is such as to provide ready entrance of fluid into any void that might tend to form during release of the armature. This also improves the release time for the mechanism. The large holding force for the mechanism is accomplished by providing a small, selected, uniform air gap between the inner pole piece and the armature.

  10. Mechanical plasticity of cells

    Science.gov (United States)

    Bonakdar, Navid; Gerum, Richard; Kuhn, Michael; Spörrer, Marina; Lippert, Anna; Schneider, Werner; Aifantis, Katerina E.; Fabry, Ben

    2016-10-01

    Under mechanical loading, most living cells show a viscoelastic deformation that follows a power law in time. After removal of the mechanical load, the cell shape recovers only incompletely to its original undeformed configuration. Here, we show that incomplete shape recovery is due to an additive plastic deformation that displays the same power-law dynamics as the fully reversible viscoelastic deformation response. Moreover, the plastic deformation is a constant fraction of the total cell deformation and originates from bond ruptures within the cytoskeleton. A simple extension of the prevailing viscoelastic power-law response theory with a plastic element correctly predicts the cell behaviour under cyclic loading. Our findings show that plastic energy dissipation during cell deformation is tightly linked to elastic cytoskeletal stresses, which suggests the existence of an adaptive mechanism that protects the cell against mechanical damage.

  11. Boosted Statistical Mechanics

    CERN Document Server

    Testa, Massimo

    2015-01-01

    Based on the fundamental principles of Relativistic Quantum Mechanics, we give a rigorous, but completely elementary, proof of the relation between fundamental observables of a statistical system when measured relatively to two inertial reference frames, connected by a Lorentz transformation.

  12. Playing at Statistical Mechanics

    Science.gov (United States)

    Clark, Paul M.; And Others

    1974-01-01

    Discussed are the applications of counting techniques of a sorting game to distributions and concepts in statistical mechanics. Included are the following distributions: Fermi-Dirac, Bose-Einstein, and most probable. (RH)

  13. Mechanical Testing Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s Mechanical Testing Laboratory in Albany, OR, helps researchers investigate materials that can withstand the heat and pressure commonly found in fossil energy...

  14. Molecular Mechanisms of Preeclampsia

    OpenAIRE

    N. Vitoratos; D. Hassiakos; Iavazzo, C.

    2012-01-01

    Preeclampsia is one of the leading causes of maternal morbidity/mortality. The pathogenesis of preeclampsia is still under investigation. The aim of this paper is to present the molecular mechanisms implicating in the pathway leading to preeclampsia.

  15. Mechanical Enterogenesis - A Review

    Directory of Open Access Journals (Sweden)

    Rebecca Stark

    2012-01-01

    Full Text Available Mechanical enterogenesis is a novel method of lengthening pre-existing intestine with distractive force. The application of mechanical force on small intestine aims to induce cellular proliferation and ultimately increase bowel length. This has been investigated primarily for the treatment of short bowel syndrome (SBS. Research has been ongoing for well over a decade in this arena and a multitude of advances have been made, both in the understanding of the biology behind force induced cellular proliferation and in the basic mechanics of force delivery systems. Important experimental models have been developed for studying this phenomenon and the collaboration of engineers and medical researchers has lead to the design of several devices that successfully lengthen small intestine. This has catapulted the field forward and there may soon be a device suitable for medical use in humans. This review analyses the past, present and future of mechanical enterogenesis.

  16. Computational Continuum Mechanics

    CERN Document Server

    Shabana, Ahmed A

    2011-01-01

    This text presents the theory of continuum mechanics using computational methods. Ideal for students and researchers, the second edition features a new chapter on computational geometry and finite element analysis.

  17. Applied mechanics of solids

    CERN Document Server

    Bower, Allan F

    2009-01-01

    Modern computer simulations make stress analysis easy. As they continue to replace classical mathematical methods of analysis, these software programs require users to have a solid understanding of the fundamental principles on which they are based. Develop Intuitive Ability to Identify and Avoid Physically Meaningless Predictions Applied Mechanics of Solids is a powerful tool for understanding how to take advantage of these revolutionary computer advances in the field of solid mechanics. Beginning with a description of the physical and mathematical laws that govern deformation in solids, the text presents modern constitutive equations, as well as analytical and computational methods of stress analysis and fracture mechanics. It also addresses the nonlinear theory of deformable rods, membranes, plates, and shells, and solutions to important boundary and initial value problems in solid mechanics. The author uses the step-by-step manner of a blackboard lecture to explain problem solving methods, often providing...

  18. Statistical mechanics of superconductivity

    CERN Document Server

    Kita, Takafumi

    2015-01-01

    This book provides a theoretical, step-by-step comprehensive explanation of superconductivity for undergraduate and graduate students who have completed elementary courses on thermodynamics and quantum mechanics. To this end, it adopts the unique approach of starting with the statistical mechanics of quantum ideal gases and successively adding and clarifying elements and techniques indispensible for understanding it. They include the spin-statistics theorem, second quantization, density matrices, the Bloch–De Dominicis theorem, the variational principle in statistical mechanics, attractive interaction, and bound states. Ample examples of their usage are also provided in terms of topics from advanced statistical mechanics such as two-particle correlations of quantum ideal gases, derivation of the Hartree–Fock equations, and Landau’s Fermi-liquid theory, among others. With these preliminaries, the fundamental mean-field equations of superconductivity are derived with maximum mathematical clarity based on ...

  19. Quantum mechanics symmetries

    CERN Document Server

    Greiner, Walter

    1989-01-01

    "Quantum Dynamics" is a major survey of quantum theory based on Walter Greiner's long-running and highly successful courses at the University of Frankfurt. The key to understanding in quantum theory is to reinforce lecture attendance and textual study by working through plenty of representative and detailed examples. Firm belief in this principle led Greiner to develop his unique course and to transform it into a remarkable and comprehensive text. The text features a large number of examples and exercises involving many of the most advanced topics in quantum theory. These examples give practical and precise demonstrations of how to use the often subtle mathematics behind quantum theory. The text is divided into five volumes: Quantum Mechanics I - An Introduction, Quantum Mechanics II - Symmetries, Relativistic Quantum Mechanics, Quantum Electrodynamics, Gauge Theory of Weak Interactions. These five volumes take the reader from the fundamental postulates of quantum mechanics up to the latest research in partic...

  20. Mechanics and thermodynamics

    CERN Document Server

    Demtröder, Wolfgang

    2017-01-01

    This introduction to classical mechanics and thermodynamics provides an accessible and clear treatment of the fundamentals. Starting with particle mechanics and an early introduction to special relativity this textbooks enables the reader to understand the basics in mechanics. The text is written from the experimental physics point of view, giving numerous real life examples and applications of classical mechanics in technology. This highly motivating presentation deepens the knowledge in a very accessible way. The second part of the text gives a concise introduction to rotational motion, an expansion to rigid bodies, fluids and gases. Finally, an extensive chapter on thermodynamics and a short introduction to nonlinear dynamics with some instructive examples intensify the knowledge of more advanced topics. Numerous problems with detailed solutions are perfect for self study.

  1. Mechanical properties of viruses.

    Science.gov (United States)

    de Pablo, Pedro J; Mateu, Mauricio G

    2013-01-01

    Structural biology techniques have greatly contributed to unveil the relationships between structure, properties and functions of viruses. In recent years, classic structural approaches are being complemented by single-molecule techniques such as atomic force microscopy and optical tweezers to study physical properties and functions of viral particles that are not accessible to classic structural techniques. Among these features are mechanical properties such as stiffness, intrinsic elasticity, tensile strength and material fatigue. The field of virus mechanics is contributing to materials science by investigating some physical parameters of "soft" biological matter and biological nano-objects. Virus mechanics studies are also starting to unveil the biological implications of physical properties of viruses. Growing evidence indicate that viruses are subjected to internal and external forces, and that they may have adapted to withstand and even use those forces. This chapter describes what is known on the mechanical properties of virus particles, their structural determinants, and possible biological implications, of which several examples are provided.

  2. Classical mechanics without determinism

    OpenAIRE

    Nikolic, H.

    2005-01-01

    Classical statistical particle mechanics in the configuration space can be represented by a nonlinear Schrodinger equation. Even without assuming the existence of deterministic particle trajectories, the resulting quantum-like statistical interpretation is sufficient to predict all measurable results of classical mechanics. In the classical case, the wave function that satisfies a linear equation is positive, which is the main source of the fundamental difference between classical and quantum...

  3. Discrete Quantum Mechanics

    OpenAIRE

    Odake, Satoru; Sasaki, Ryu

    2011-01-01

    A comprehensive review of the discrete quantum mechanics with the pure imaginary shifts and the real shifts is presented in parallel with the corresponding results in the ordinary quantum mechanics. The main subjects to be covered are the factorised Hamiltonians, the general structure of the solution spaces of the Schroedinger equation (Crum's theorem and its modification), the shape invariance, the exact solvability in the Schroedinger picture as well as in the Heisenberg picture, the creati...

  4. Problems in quantum mechanics

    CERN Document Server

    Gol'dman, I I

    2010-01-01

    A comprehensive collection of problems of varying degrees of difficulty in nonrelativistic quantum mechanics, with answers and completely worked-out solutions. Among the topics: one-dimensional motion, transmission through a potential barrier, commutation relations, angular momentum and spin, and motion of a particle in a magnetic field. An ideal adjunct to any textbook in quantum mechanics, useful in courses in atomic and nuclear physics, mathematical methods in physics, quantum statistics and applied differential equations. 1961 edition.

  5. Advanced Mechanics of Piezoelectricity

    CERN Document Server

    Qin, Qing-Hua

    2013-01-01

    "Advanced Mechanics of Piezoelectricity" presents a comprehensive treatment of piezoelectric materials using linear electroelastic theory, symplectic models, and Hamiltonian systems. It summarizes the current state of practice and presents the most recent research findings in piezoelectricity. It is intended for researchers and graduate students in the fields of applied mechanics, material science and engineering, computational engineering, and aerospace engineering. Dr. Qinghua Qin is a professor at the School of Engineering, Australian National University, Australia.

  6. MECHANISMS IN ENDOCRINOLOGY

    DEFF Research Database (Denmark)

    Allin, Kristine H.; Nielsen, Trine; Pedersen, Oluf.

    2015-01-01

    Perturbations of the composition and function of the gut microbiota have been associated with metabolic disorders including obesity, insulin resistance and type 2 diabetes. Studies on mice have demonstrated several underlying mechanisms including host signalling through bacterial lipopolysacchari......Perturbations of the composition and function of the gut microbiota have been associated with metabolic disorders including obesity, insulin resistance and type 2 diabetes. Studies on mice have demonstrated several underlying mechanisms including host signalling through bacterial...

  7. Bubble-sweeping mechanisms

    Institute of Scientific and Technical Information of China (English)

    WANG; Hao; (王; 昊); PENG; Xiaofeng; (彭晓峰); WANG; Buxuan; (王补宣); LEE; Duzhong; (李笃中)

    2003-01-01

    A series of subcooled boiling experiments was conducted on very small platinum wires having diameters of 0.1 and 0.025 mm. Vapor bubbles were visually observed to sweep back and forth along the wires in the experiments. The dynamic characteristics of bubble-sweeping phenomenon are described, and the induced bubble interaction and nonlinear growth are investigated to understand the boiling heat transfer mechanisms. An unsymmetrical temperature model is proposed to explain the physical mechanism.

  8. Mechanical Service; Service Mechanique

    Energy Technology Data Exchange (ETDEWEB)

    Alliaume, T.; Benoit, A.; Bonin, H.; Ducimetiere, D.; Essertaize, D.; Gelin, G.; Guillot, G.; Lemoine, C.; Mabo, J.C.; Mounier, F.; Tissot, S.; Verdier, G. [Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)

    1998-12-31

    The service studies the mechanical part of the experiment or detectors used by the physics groups in collaboration with the physicists, engineers and the technicians of the experiment assistance group as well as with other technical groups. The mechanical service was implied in the following projects: CMS, VIRGO (the IGISOL ion guide chamber), PIAFE, NA50 (reaction chamber, metallic cluster source), ORION, SICANE, EDELWEISS II 2 figs.

  9. Mechanisms for chromosome segregation.

    Science.gov (United States)

    Bouet, Jean-Yves; Stouf, Mathieu; Lebailly, Elise; Cornet, François

    2014-12-01

    Bacteria face the problem of segregating their gigantic chromosomes without a segregation period restricted in time and space, as Eukaryotes do. Segregation thus involves multiple activities, general or specific of a chromosome region and differentially controlled. Recent advances show that these various mechanisms conform to a “pair and release” rule, which appears as a general rule in DNA segregation. We describe the latest advances in segregation of bacterial chromosomes with emphasis on the different pair and release mechanisms.

  10. Elementary Nonrelativistic Quantum Mechanics

    CERN Document Server

    Rosu, H C

    2000-01-01

    This is a graduate course on elementary quantum mechanics written for the benefit of undergraduate and graduate students. It is the English version of physics/0003106, which I did at the suggestion of several students from different countries. The topics included refer to the postulates of quantum mechanics, one-dimensional barriers and wells, angular momentum and spin, WKB method, harmonic oscillator, hydrogen atom, quantum scattering, and partial waves

  11. Mechanical Engineering for Electronics.

    OpenAIRE

    Was, Loïc

    2012-01-01

    Schlumberger drilling tools are exposed to very hard loading conditions (shocks, vibrations, thermal cycling) while performing a job. As these tools are full of electronics, issues can quickly come from electronics failure. Mechanisms of failure occurring in electronics are very complex but can be predicted in some cases. The first part of the thesis describes in which context mechanical engineering applied to electronics is used in Schlumberger. The different kinds of failure which will be i...

  12. Phase Field Fracture Mechanics.

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Brett Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    For this assignment, a newer technique of fracture mechanics using a phase field approach, will be examined and compared with experimental data for a bend test and a tension test. The software being used is Sierra Solid Mechanics, an implicit/explicit finite element code developed at Sandia National Labs in Albuquerque, New Mexico. The bend test experimental data was also obtained at Sandia Labs while the tension test data was found in a report online from Purdue University.

  13. Holography and Quantum Mechanics

    CERN Document Server

    Wang, X J

    2002-01-01

    It is illustrated that quantum mechanics can be interpreted as holographic projection of higher dimension classical gravity. In this explanation every quantum path in D-dimension is dual to a classical path of (D+1)-dimension gravity under definite holographic projection. I consider 2-dimension non-relativitic free particle and harmonic oscillator as two examples, and find their gravity dual. I conjecture that every quantum mechanics system has their dual gravity description.

  14. Mechanics of underwater noise

    CERN Document Server

    Ross, Donald

    1976-01-01

    Mechanics of Underwater Noise elucidates the basic mechanisms by which noise is generated, transmitted by structures and radiated into the sea. Organized into 10 chapters, this book begins with a description of noise, decibels and levels, significance of spectra, and passive sonar equation. Subsequent chapters discuss sound waves in liquids; acoustic radiation fundamentals; wind-generated ocean ambient noise; vibration isolation and structural damping; and radiation by plate flexural vibrations. Other chapters address cavitation, propeller cavitation noise, radiation by fluctuating-force (dipo

  15. Painful neuropathy: Mechanisms.

    Science.gov (United States)

    Lee-Kubli, Corinne A; Calcutt, Nigel A

    2014-01-01

    Painful neuropathy, like the other complications of diabetes, is a growing healthcare concern. Unfortunately, current treatments are of variable efficacy and do not target underlying pathogenic mechanisms, in part because these mechanisms are not well defined. Rat and mouse models of type 1 diabetes are frequently used to study diabetic neuropathy, with rats in particular being consistently reported to show allodynia and hyperalgesia. Models of type 2 diabetes are being used with increasing frequency, but the current literature on the progression of indices of neuropathic pain is variable and relatively few therapeutics have yet been developed in these models. While evidence for spontaneous pain in rodent models is sparse, measures of evoked mechanical, thermal and chemical pain can provide insight into the pathogenesis of the condition. The stocking and glove distribution of pain tantalizingly suggests that the generator site of neuropathic pain is found within the peripheral nervous system. However, emerging evidence demonstrates that amplification in the spinal cord, via spinal disinhibition and neuroinflammation, and also in the brain, via enhanced thalamic activity or decreased cortical inhibition, likely contribute to the pathogenesis of painful diabetic neuropathy. Several potential therapeutic strategies have emerged from preclinical studies, including prophylactic treatments that intervene against underlying mechanisms of disease, treatments that prevent gains of nociceptive function, treatments that suppress enhancements of nociceptive function, and treatments that impede normal nociceptive mechanisms. Ongoing challenges include unraveling the complexity of underlying pathogenic mechanisms, addressing the potential disconnect between the perceived location of pain and the actual pain generator and amplifier sites, and finding ways to identify which mechanisms operate in specific patients to allow rational and individualized choice of targeted therapies.

  16. Advanced mechanics of solids

    CERN Document Server

    Bruhns, Otto T

    2003-01-01

    Mechanics, and in particular, the mechanics of solids, forms the basis of all engi­ neering sciences. It provides the essential foundations for understanding the action of forces on bodies, and the effects of these forces on the straining of the body on the one hand, and on the deformation and motion of the body on the other. Thus, it provides the solutions of many problems with which the would-be engineer is going to be confronted with on a daily basis. In addition, in engineering studies, mechanics has a more vital importance, which many students appreciate only much later. Because of its clear, and analyt­ ical setup, it aids the student to a great extent in acquiring the necessary degree of abstraction ability, and logical thinking, skills without which no engineer in the practice today would succeed. Many graduates have confirmed to me that learning mechanics is generally per­ ceived as difficult. On the other hand, they always also declared that the preoccu­ pation with mechanics made an essential c...

  17. Theory of Parallel Mechanisms

    CERN Document Server

    Huang, Zhen; Ding, Huafeng

    2013-01-01

    This book contains mechanism analysis and synthesis. In mechanism analysis, a mobility methodology is first systematically presented. This methodology, based on the author's screw theory, proposed in 1997, of which the generality and validity was only proved recently,  is a very complex issue, researched by various scientists over the last 150 years. The principle of kinematic influence coefficient and its latest developments are described. This principle is suitable for kinematic analysis of various 6-DOF and lower-mobility parallel manipulators. The singularities are classified by a new point of view, and progress in position-singularity and orientation-singularity is stated. In addition, the concept of over-determinate input is proposed and a new method of force analysis based on screw theory is presented. In mechanism synthesis, the synthesis for spatial parallel mechanisms is discussed, and the synthesis method of difficult 4-DOF and 5-DOF symmetric mechanisms, which was first put forward by the a...

  18. Mechanism of charity activity

    Directory of Open Access Journals (Sweden)

    Roman B. Golovkin

    2015-12-01

    Full Text Available Objective to establish the essential properties of the mechanism of charitable activities and to formulate the concept of quotmechanism of charitable activityquot. Methods the objective of the study is achieved using the complex of methods which are based on the interaction of dialectical and metaphysical analysis the epistemological properties of which allowed to reveal various aspects of the charitable activities mechanism functioning taking into account the principles of comprehensiveness complexity specificity and objectivity of the research. Results the rules are stated of using the term quotmechanismquot to characterize actions of state and law the essence of the charity mechanism is defined the definition of quotthe mechanism of charitable activity quot is formulated. Scientific novelty for the first time at theoretical level in legal science the definition of quotthe mechanism of charitable activityquot is formulated and its essential properties are set. Practical significance the research will contribute to improving the legal regulation in the field of philanthropy as well as to improving the efficiency and quality of charitable activity in the Russian Federation. nbsp

  19. Resonant scanning mechanism

    Science.gov (United States)

    Wallace, John; Newman, Mike; Gutierrez, Homero; Hoffman, Charlie; Quakenbush, Tim; Waldeck, Dan; Leone, Christopher; Ostaszewski, Miro

    2014-10-01

    Ball Aerospace & Technologies Corp. developed a Resonant Scanning Mechanism (RSM) capable of combining a 250- Hz resonant scan about one axis with a two-hertz triangular scan about the orthogonal axis. The RSM enables a rapid, high-density scan over a significant field of regard (FOR) while minimizing size, weight, and power requirements. The azimuth scan axis is bearing mounted allowing for 30° of mechanical travel, while the resonant elevation axis is flexure and spring mounted with five degrees of mechanical travel. Pointing-knowledge error during quiescent static pointing at room temperature across the full range is better than 100 μrad RMS per axis. The compact design of the RSM, roughly the size of a soda can, makes it an ideal mechanism for use on low-altitude aircraft and unmanned aerial vehicles. Unique aspects of the opto-mechanical design include i) resonant springs which allow for a high-frequency scan axis with low power consumption; and ii) an independent lower-frequency scan axis allowing for a wide FOR. The pointing control system operates each axis independently and employs i) a position loop for the azimuth axis; and ii) a unique combination of parallel frequency and amplitude control loops for the elevation axis. All control and pointing algorithms are hosted on a 200-MHz microcontroller with 516 KB of RAM on a compact 3"×4" digital controller, also of Ball design.

  20. Conventional mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Tobias Joseph

    2010-01-01

    Full Text Available The provision of mechanical ventilation for the support of infants and children with respiratory failure or insufficiency is one of the most common techniques that are performed in the Pediatric Intensive Care Unit (PICU. Despite its widespread application in the PICUs of the 21st century, before the 1930s, respiratory failure was uniformly fatal due to the lack of equipment and techniques for airway management and ventilatory support. The operating rooms of the 1950s and 1960s provided the arena for the development of the manual skills and the refinement of the equipment needed for airway management, which subsequently led to the more widespread use of endotracheal intubation thereby ushering in the era of positive pressure ventilation. Although there seems to be an ever increasing complexity in the techniques of mechanical ventilation, its successful use in the PICU should be guided by the basic principles of gas exchange and the physiology of respiratory function. With an understanding of these key concepts and the use of basic concepts of mechanical ventilation, this technique can be successfully applied in both the PICU and the operating room. This article reviews the basic physiology of gas exchange, principles of pulmonary physiology, and the concepts of mechanical ventilation to provide an overview of the knowledge required for the provision of conventional mechanical ventilation in various clinical arenas.

  1. Epigenetics: Biology's Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Richard A Jorgensen

    2011-04-01

    Full Text Available The perspective presented here is that modern genetics is at a similar stage of development as were early formulations of quantum mechanics theory in the 1920's and that in 2010 we are at the dawn of a new revolution in genetics that promises to enrich and deepen our understanding of the gene and the genome. The interrelationships and interdependence of two views of the gene - the molecular biological view and the epigenetic view - are explored, and it is argued that the classical molecular biological view is incomplete without incorporation of the epigenetic perspective and that in a sense the molecular biological view has been evolving to include the epigenetic view. Intriguingly, this evolution of the molecular view toward the broader and more inclusive epigenetic view of the gene has an intriguing, if not precise, parallel in the evolution of concepts of atomic physics from Newtonian mechanics to quantum mechanics that are interesting to consider.

  2. Epigenetics: Biology's Quantum Mechanics.

    Science.gov (United States)

    Jorgensen, Richard A

    2011-01-01

    The perspective presented here is that modern genetics is at a similar stage of development as were early formulations of quantum mechanics theory in the 1920s and that in 2010 we are at the dawn of a new revolution in genetics that promises to enrich and deepen our understanding of the gene and the genome. The interrelationships and interdependence of two views of the gene - the molecular biological view and the epigenetic view - are explored, and it is argued that the classical molecular biological view is incomplete without incorporation of the epigenetic perspective and that in a sense the molecular biological view has been evolving to include the epigenetic view. Intriguingly, this evolution of the molecular view toward the broader and more inclusive epigenetic view of the gene has an intriguing, if not precise, parallel in the evolution of concepts of atomic physics from Newtonian mechanics to quantum mechanics that are interesting to consider.

  3. Integrating function and mechanism.

    Science.gov (United States)

    McNamara, John M; Houston, Alasdair I

    2009-12-01

    Behavioural ecology often makes the assumption that animals can respond flexibly by adopting the optimal behaviour for each circumstance. However, as ethologists have long known, behaviour is determined by mechanisms that are not optimal in every circumstance. As we discuss here, we believe that it is necessary to integrate these separate traditions by considering the evolution of mechanisms, an approach referred to as 'Evo-mecho'. This integration is timely because there is a growing awareness of the importance of environmental complexity in shaping behaviour; there are established and effective computational procedures for simulating evolution and there is rapidly increasing knowledge of the neuronal basis of decision-making. Although behavioural ecologists have built complex models of optimal behaviour in simple environments, we argue that they need to focus on simple mechanisms that perform well in complex environments.

  4. Crude oil burning mechanisms

    DEFF Research Database (Denmark)

    van Gelderen, Laurens; Malmquist, L.M.V.; Jomaas, Grunde

    2015-01-01

    In order to improve predictions for the burning efficiency and the residue composition of in-situ burning of crude oil, the burning mechanism of crude oil was studied in relation to the composition of its hydrocarbon mixture, before, during and after the burning. The surface temperature, flame...... to the predictions of four conceptual models that describe the burning mechanism of multicomponent fuels. Based on the comparisons, hydrocarbon liquids were found to be best described by the Equilibrium Flash Vaporization model, showing a constant gas composition and gasification rate. The multicomponent fuels...... followed the diffusion-limited gasification model, showing a change in the hydrocarbon composition of the fuel and its evaporating gases, as well as a decreasing gasification rate, as the burning progressed. This burning mechanism implies that the residue composition and burning efficiency mainly depend...

  5. MECHANISMS IN ENDOCRINOLOGY

    DEFF Research Database (Denmark)

    Sonne, David P; Hansen, Morten; Knop, Filip K

    2014-01-01

    Bile acid sequestrants have been used for decades for the treatment of hypercholesterolaemia. Sequestering of bile acids in the intestinal lumen interrupts enterohepatic recirculation of bile acids, which initiate feedback mechanisms on the conversion of cholesterol into bile acids in the liver......, thereby lowering cholesterol concentrations in the circulation. In the early 1990s, it was observed that bile acid sequestrants improved glycaemic control in patients with type 2 diabetes. Subsequently, several studies confirmed the finding and recently - despite elusive mechanisms of action - bile acid...... of bile acid sequestrants in the treatment of type 2 diabetes, the possible mechanism of action and the role of bile acid-induced secretion of GLP1 via activation of TGR5....

  6. Fundamentals of quantum mechanics

    CERN Document Server

    House, J E

    2017-01-01

    Fundamentals of Quantum Mechanics, Third Edition is a clear and detailed introduction to quantum mechanics and its applications in chemistry and physics. All required math is clearly explained, including intermediate steps in derivations, and concise review of the math is included in the text at appropriate points. Most of the elementary quantum mechanical models-including particles in boxes, rigid rotor, harmonic oscillator, barrier penetration, hydrogen atom-are clearly and completely presented. Applications of these models to selected “real world” topics are also included. This new edition includes many new topics such as band theory and heat capacity of solids, spectroscopy of molecules and complexes (including applications to ligand field theory), and small molecules of astrophysical interest.

  7. The graviton Higgs mechanism

    CERN Document Server

    Arraut, Ivan

    2015-01-01

    The Higgs mechanism at the graviton level formulated as a Vainshtein mechanism in time domains implies that the extra-degrees of freedom become relevant depending on the direction of time (frame of reference) with respect to the preferred time direction (preferred frame) defined by the St\\"uckelberg function $T_0(r,t)$ which contains the information of the extra-degrees of freedom of the theory. In this manuscript, I make the general definition of the Higgs mechanism by analyzing the gauge symmetries of the action and the general form of the vacuum solutions for the graviton field. In general, the symmetry generators depending explicitly on the St\\"uckelberg fields are broken at the vacuum level. These broken generators, define the number of Nambu-Goldstone bosons which will be eating up by the dynamical metric in order to become massive.

  8. Stochastic Neutrino Mixing Mechanism

    CERN Document Server

    Guzzo, M M; Peres, O L G; Zavanin, E M

    2013-01-01

    We propose a mechanism which provides an explanation of the Gallium and antineutrino reactor anomalies. Differently from original Pontecorvo's hypothesis, this mechanism is based on the phenomenological assumption in which the admixture of neutrino mass eigenstates in the moments of neutrino creation and detection can assume different configurations around the admixture parametrized by the usual values of the mixing angles $\\theta_{12}$, $\\theta_{23}$ and $\\theta_{13}$. For simplicity, we assume a Gaussian distribution for the mixing angles in such a way that the average value of this distribution is given by the usual values of the mixing angles and the width of the Gaussian is denoted by $\\alpha$. We show that the proposed mechanism provides a possible explanation for very short-baseline neutrino disappearance, necessary to accommodate Gallium and antineutrino reactor anomalies, which is not allowed in usual neutrino oscillations based on Pontecorvo's original hypotheses. We also can describe high-energy os...

  9. The graviton Higgs mechanism

    Science.gov (United States)

    Arraut, Ivan

    2015-09-01

    The Higgs mechanism at the graviton level formulated as a Vainshtein mechanism in time domains implies that the extra-degrees of freedom become relevant depending on the direction of time (frame of reference) with respect to the preferred time direction (preferred frame) defined by the Stückelberg function T_0(r,t) which contains the information of the extra-degrees of freedom of the theory. In this manuscript, I make the general definition of the Higgs mechanism by analyzing the gauge symmetries of the action and the general form of the vacuum solutions for the graviton field. In general, the symmetry generators depending explicitly on the Stückelberg fields are broken at the vacuum level. These broken generators, define the number of Nambu-Goldstone bosons which will be eating up by the dynamical metric in order to become massive.

  10. Molecular mechanisms of meditation.

    Science.gov (United States)

    Jindal, Vishal; Gupta, Sorab; Das, Ritwik

    2013-12-01

    Meditation is a complex process involving change in cognition, memory, and social and emotional control, and causes improvement in various cardiovascular, neurological, autoimmune, and renal pathologies. Meditation also become widely used in medical and psychological treatment therapies for stress-related physical and mental disorders. But still, biological mechanisms in terms of effect on brain and body are poorly understood. This paper explains the basic changes due to meditation in cerebral cortex, prefrontal area, cingulate gyrus, neurotransmitters, white matter, autonomic nervous system, limbic system, cytokines, endorphins, hormones, etc. The following is a review of the current literature regarding the various neurophysiological mechanisms, neuro-endocrine mechanisms, neurochemical substrates, etc. that underlies the complex processes of meditation.

  11. Mechanical Biological Treatment

    DEFF Research Database (Denmark)

    Bilitewski, B-; Oros, Christiane; Christensen, Thomas Højlund

    2011-01-01

    or residual waste (after some recyclables removed at the source). The concept was originally to reduce the amount of waste going to landfill, but MBT technologies are today also seen as plants recovering fuel as well as material fractions. As the name suggests the technology combines mechanical treatment......The basic processes and technologies of composting and anaerobic digestion, as described in the previous chapters, are usually used for specific or source-separated organic waste flows. However, in the 1990s mechanical biological waste treatment technologies (MBT) were developed for unsorted...... technologies (screens, sieves, magnets, etc.) with biological technologies (composting, anaerobic digestion). Two main technologies are available: Mechanical biological pretreatment (MBP), which first removes an RDF fraction and then biologically treats the remaining waste before most of it is landfilled...

  12. Fracture Mechanics of Concrete

    DEFF Research Database (Denmark)

    Ulfkjær, Jens Peder

    Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high-strength......Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high......-strength concrete. Chapter 2 A description of the factors which influence the strength and cracking of concrete and high strength concrete is made. Then basic linear fracture mechanics is outlined followed by a description and evaluation of the models used to describe concrete fracture in tension. The chapter ends...

  13. Mechanical engineer's reference book

    CERN Document Server

    Parrish, A

    1973-01-01

    Mechanical Engineer's Reference Book: 11th Edition presents a comprehensive examination of the use of Systéme International d' Unités (SI) metrication. It discusses the effectiveness of such a system when used in the field of engineering. It addresses the basic concepts involved in thermodynamics and heat transfer. Some of the topics covered in the book are the metallurgy of iron and steel; screw threads and fasteners; hole basis and shaft basis fits; an introduction to geometrical tolerancing; mechanical working of steel; high strength alloy steels; advantages of making components as castings

  14. Problems in quantum mechanics

    CERN Document Server

    Kogan, VI; Gersch, Harold

    2011-01-01

    Written by a pair of distinguished Soviet mathematicians, this compilation presents 160 lucidly expressed problems in nonrelativistic quantum mechanics plus completely worked-out solutions. Some were drawn from the authors' courses at the Moscow Institute of Engineering, but most were prepared especially for this book. A high-level supplement rather than a primary text, it constitutes a masterful complement to advanced undergraduate and graduate texts and courses in quantum mechanics.The mathematics employed in the proofs of the problems-asymptotic expansions of functions, Green's functions, u

  15. Fundamentals of continuum mechanics

    CERN Document Server

    Rudnicki, John W

    2014-01-01

    A concise introductory course text on continuum mechanics Fundamentals of Continuum Mechanics focuses on the fundamentals of the subject and provides the background for formulation of numerical methods for large deformations and a wide range of material behaviours. It aims to provide the foundations for further study, not just of these subjects, but also the formulations for much more complex material behaviour and their implementation computationally.  This book is divided into 5 parts, covering mathematical preliminaries, stress, motion and deformation, balance of mass, momentum and energ

  16. Classical mechanics with Maxima

    CERN Document Server

    Timberlake, Todd Keene

    2016-01-01

    This book guides undergraduate students in the use of Maxima—a computer algebra system—in solving problems in classical mechanics. It functions well as a supplement to a typical classical mechanics textbook. When it comes to problems that are too difficult to solve by hand, computer algebra systems that can perform symbolic mathematical manipulations are a valuable tool. Maxima is particularly attractive in that it is open-source, multiple-platform software that students can download and install free of charge. Lessons learned and capabilities developed using Maxima are easily transferred to other, proprietary software.

  17. Synthesis of Mechanisms

    DEFF Research Database (Denmark)

    Hansen, John Michael

    1999-01-01

    These notes describe an automated procedure for analysis and synthesis of mechanisms. The analysis method is based on the body coordinate formulation, and the synthesis is based on applying optimization methods, used to minimize the difference between an actual and a desired behaviour......These notes describe an automated procedure for analysis and synthesis of mechanisms. The analysis method is based on the body coordinate formulation, and the synthesis is based on applying optimization methods, used to minimize the difference between an actual and a desired behaviour...

  18. Elementary quantum mechanics

    CERN Document Server

    Saxon, David S

    2012-01-01

    Based on lectures for an undergraduate UCLA course in quantum mechanics, this volume focuses on the formulas of quantum mechanics rather than applications. Widely used in both upper-level undergraduate and graduate courses, it offers a broad self-contained survey rather than in-depth treatments.Topics include the dual nature of matter and radiation, state functions and their interpretation, linear momentum, the motion of a free particle, Schrödinger's equation, approximation methods, angular momentum, and many other subjects. In the interests of keeping the mathematics as simple as possible, m

  19. 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

  20. Mechanism of artificial heart

    CERN Document Server

    Yamane, Takashi

    2016-01-01

    This book first describes medical devices in relation to regenerative medicine before turning to a more specific topic: artificial heart technologies. Not only the pump mechanisms but also the bearing, motor mechanisms, and materials are described, including expert information. Design methods are described to enhance hemocompatibility: main concerns are reduction of blood cell damage and protein break, as well as prevention of blood clotting. Regulatory science from R&D to clinical trials is also discussed to verify the safety and efficacy of the devices.

  1. Relativistic wave mechanics

    CERN Document Server

    Corinaldesi, Ernesto

    1963-01-01

    Geared toward advanced undergraduate and graduate students of physics, this text provides readers with a background in relativistic wave mechanics and prepares them for the study of field theory. The treatment originated as a series of lectures from a course on advanced quantum mechanics that has been further amplified by student contributions.An introductory section related to particles and wave functions precedes the three-part treatment. An examination of particles of spin zero follows, addressing wave equation, Lagrangian formalism, physical quantities as mean values, translation and rotat

  2. Mechanics of fluid flow

    CERN Document Server

    Basniev, Kaplan S; Chilingar, George V 0

    2012-01-01

    The mechanics of fluid flow is a fundamental engineering discipline explaining both natural phenomena and human-induced processes, and a thorough understanding of it is central to the operations of the oil and gas industry.  This book, written by some of the world's best-known and respected petroleum engineers, covers the concepts, theories, and applications of the mechanics of fluid flow for the veteran engineer working in the field and the student, alike.  It is a must-have for any engineer working in the oil and gas industry.

  3. Computational statistical mechanics

    CERN Document Server

    Hoover, WG

    1991-01-01

    Computational Statistical Mechanics describes the use of fast computers to simulate the equilibrium and nonequilibrium properties of gases, liquids, and solids at, and away from equilibrium. The underlying theory is developed from basic principles and illustrated by applying it to the simplest possible examples. Thermodynamics, based on the ideal gas thermometer, is related to Gibb's statistical mechanics through the use of Nosé-Hoover heat reservoirs. These reservoirs use integral feedback to control temperature. The same approach is carried through to the simulation and anal

  4. Problems in classical mechanics

    CERN Document Server

    Katkar, L N

    2014-01-01

    Problems in classical mechanics presents a lucid treatment of the formulations of Lagrangian, Hamiltonian, and the Principles of Calculus of Variations etc. important for the study of modern physics. The study of classical mechanics prepares students to apply the principles and the mathematical tools to solve real life problems. The book also incorporates and discusses in detail topics such as Central Force Motion, Rigid Body Motion and Canonical Transformations. KEY FEATURES: Around 200 solved examples with complete mathematical theory Around 70 examples given as an exercise to test and develop students understanding The physical interpretation of the Hamiltonian is highlighted

  5. Dynamically assisted Schwinger mechanism.

    Science.gov (United States)

    Schützhold, Ralf; Gies, Holger; Dunne, Gerald

    2008-09-26

    We study electron-positron pair creation from the Dirac vacuum induced by a strong and slowly varying electric field (Schwinger effect) which is superimposed by a weak and rapidly changing electromagnetic field (dynamical pair creation). In the subcritical regime where both mechanisms separately are strongly suppressed, their combined impact yields a pair creation rate which is dramatically enhanced. Intuitively speaking, the strong electric field lowers the threshold for dynamical particle creation--or, alternatively, the fast electromagnetic field generates additional seeds for the Schwinger mechanism. These findings could be relevant for planned ultrahigh intensity lasers.

  6. 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.

  7. Elementary Quantum Mechanics

    CERN Document Server

    Rosu, H C

    2000-01-01

    This is the first graduate course on elementary quantum mechanics in Internet written in Romanian for the benefit of Romanian speaking students (Romania and Moldova). It is a translation (with corrections) of the Spanish version of the course (physics/9808031, English translation is under consideration), which I did at the request of students of physics in Bucharest. The topics included refer to the postulates of quantum mechanics, one-dimensional barriers and wells, angular momentum and spin, WKB method, harmonic oscillator, hydrogen atom, quantum scattering, and partial waves

  8. Vortex mechanism in hydrocyclones

    Institute of Scientific and Technical Information of China (English)

    徐继润; 刘正宁; 邢军; 李新跃; 黄慧; 徐海燕; 罗茜

    2001-01-01

    On the basis of analyzing the vortex characteristics, a new mechanism of the vortex formation in hydrocyclones is developed. The main concept of the mechanism is that the vortex flow in a hydrocyclone is resulted from the overlapping of container rotation and hole leakage. The model is then used to explain the compound distribution of free vortex and forced vortex, predict the similarity of tangential velocity at different input pressures, and make count of the principle of small hydrocyclone with lower cut-size than large one. Meanwhile a new possible approach to a large hydro-cyclone with lower cut-size by minimizing or eliminating the air core is discussed briefly.

  9. Mechanics of soft materials

    CERN Document Server

    Volokh, Konstantin

    2016-01-01

    This book provides a concise introduction to soft matter modelling. It offers an up-to-date review of continuum mechanical description of soft and biological materials from the basics to the latest scientific materials. It includes multi-physics descriptions, such as chemo-, thermo-, electro- mechanical coupling. It derives from a graduate course at Technion that has been established in recent years. It presents original explanations for some standard materials and features elaborated examples on all topics throughout the text. PowerPoint lecture notes can be provided to instructors. .

  10. Mechanical Parking System Logistics

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    As the number of motor vehicles increases rapidly in many populated countries, t he shortage of parking space has become a difficult problem to all cities around the world. The contradiction between the shortage of parking space and the incr easing number of motor vehicles is still growing in the recent years. The utiliz ation of various kinds of mechanical parking facilities is an effective solution to this problem. How to organize a reasonable logistics system in a mechanical parking lot so that as man...

  11. Experimental unsaturated soil mechanics

    CERN Document Server

    Delage, Pierre

    2008-01-01

    In this general report, experimental systems and procedures of investigating the hydro-mechanical behaviour of unsaturated soils are presented. The water retention properties of unsaturated soils are commented and linked to various physical parameters and properties of the soils. Techniques of controlling suction are described together with their adaptation in various laboratory testing devices. Some typical features of the mechanical behaviour of unsaturated soils are presented within an elasto-plastic framework. An attempt to describe the numerous and significant recent advances in the investigation of the behaviour of unsaturated soils, including the contributions to this Conference, is proposed.

  12. Quantum mechanics selected topics

    CERN Document Server

    Perelomov, Askold Mikhailovich

    1998-01-01

    It can serve as a good supplement to any quantum mechanics textbook, filling the gap between standard textbooks and higher-level books on the one hand and journal articles on the other. This book provides a detailed treatment of the scattering theory, multidimensional quasi-classical approximation, non-stationary problems for oscillators and the theory of unstable particles. It will be useful for postgraduate students and researchers who wish to find new, interesting information hidden in the depths of non-relativistic quantum mechanics.

  13. Mechanisms of restenosis.

    OpenAIRE

    Casscells, W; Engler, D; Willerson, J. T.

    1994-01-01

    Restenosis after percutaneous transluminal coronary angioplasty remains a problem, which suggests that we still do not fully understand its mechanisms. We review here the current understanding of the cell biology of restenosis, including clinical correlation (risk factors), randomized clinical trials, human histology, animal models, and in vitro studies.

  14. Mechanical Measurements Laboratory

    CERN Multimedia

    Maximilien Brice

    2007-01-01

    The CERN mechanical measurements team check the sensors on one of the ATLAS inner detector end-caps using high precision measurement equipment. Remote checks like this must be made on these sensitive detector components before they can be transported to make sure that all systems are working correctly.

  15. Statistical mechanics of pluripotency.

    Science.gov (United States)

    MacArthur, Ben D; Lemischka, Ihor R

    2013-08-01

    Recent reports using single-cell profiling have indicated a remarkably dynamic view of pluripotent stem cell identity. Here, we argue that the pluripotent state is not well defined at the single-cell level but rather is a statistical property of stem cell populations, amenable to analysis using the tools of statistical mechanics and information theory.

  16. Residential Mechanical Precooling

    Energy Technology Data Exchange (ETDEWEB)

    German, a. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Hoeschele, M. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)

    2014-12-01

    This research conducted by the Alliance for Residential Building Innovation team evaluated mechanical air conditioner pre-cooling strategies in homes throughout the United States. EnergyPlus modeling evaluated two homes with different performance characteristics in seven climates. Results are applicable to new construction homes and most existing homes built in the last 10 years, as well as fairly efficient retrofitted homes.

  17. Air-Conditioning Mechanic.

    Science.gov (United States)

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by air conditioning mechanics. Addressed in the four chapters, or lessons, of the manual are the following topics: principles of air conditioning, refrigeration components as…

  18. Basic Retention Mechanisms

    DEFF Research Database (Denmark)

    Jensen, Bror Skytte; Jensen, H.

    1986-01-01

    . The data for kaolinite were similarly interpreted as adsorption of hydroxylated complexes of the polyvalent cations, a mechanism which has previously been suggested for the adsorption of heavy metals onto muds, sludges and organic debris. In the case of kaolinite, indications of additional reactions like...

  19. Abstractions for Mechanical Systems

    DEFF Research Database (Denmark)

    Sloth, Christoffer; Wisniewski, Rafael

    2012-01-01

    mechanical system. The tangential manifolds are generated using constants of motion, which can be derived from Noether's theorem. The transversal manifolds are subsequently generated on a reduced space, given by the Routhian, via action-angle coordinates. The method fully applies for integrable systems. We...

  20. Structured Mechanical Collage.

    Science.gov (United States)

    Huang, Zhe; Wang, Jiang; Fu, Hongbo; Lau, Rynson W H

    2014-07-01

    We present a method to build 3D structured mechanical collages consisting of numerous elements from the database given artist-designed proxy models. The construction is guided by some graphic design principles, namely unity, variety and contrast. Our results are visually more pleasing than previous works as confirmed by a user study.

  1. Fault-Mechanism Simulator

    Science.gov (United States)

    Guyton, J. W.

    1972-01-01

    An inexpensive, simple mechanical model of a fault can be produced to simulate the effects leading to an earthquake. This model has been used successfully with students from elementary to college levels and can be demonstrated to classes as large as thirty students. (DF)

  2. Horticultural Mechanics Competencies

    Science.gov (United States)

    Shipley, W. Edward

    1974-01-01

    Ornamental horticulture teachers and managers of ornamental horticulture businesses were surveyed to determine which agricultural mechanics knowledges and skills are needed for entry-level employment in nursery, greenhouse, turf, and landscape management, which are common to the four areas, and the appropriate grade level at which they should be…

  3. Principles of Mechanical Excavation

    Energy Technology Data Exchange (ETDEWEB)

    Lislerud, A. [Tamrock Corp., Tampere (Finland)

    1997-12-01

    Mechanical excavation of rock today includes several methods such as tunnel boring, raiseboring, roadheading and various continuous mining systems. Of these raiseboring is one potential technique for excavating shafts in the repository for spent nuclear fuel and dry blind boring is promising technique for excavation of deposition holes, as demonstrated in the Research Tunnel at Olkiluoto. In addition, there is potential for use of other mechanical excavation techniques in different parts of the repository. One of the main objectives of this study was to analyze the factors which affect the feasibility of mechanical rock excavation in hard rock conditions and to enhance the understanding of factors which affect rock cutting so as to provide an improved basis for excavator performance prediction modeling. The study included the following four main topics: (a) phenomenological model based on similarity analysis for roller disk cutting, (b) rock mass properties which affect rock cuttability and tool life, (c) principles for linear and field cutting tests and performance prediction modeling and (d) cutter head lacing design procedures and principles. As a conclusion of this study, a test rig was constructed, field tests were planned and started up. The results of the study can be used to improve the performance prediction models used to assess the feasibility of different mechanical excavation techniques at various repository investigation sites. (orig.). 21 refs.

  4. 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…

  5. Mechanical cleaning of graphene

    NARCIS (Netherlands)

    Goossens, A.M.; Calado, V.E.; Barreiro, A.; Watanabe, K.; Taniguchi, T.; Vandersypen, L.M.K.

    2012-01-01

    Contamination of graphene due to residues from nanofabrication often introduces background doping and reduces electron mobility. For samples of high electronic quality, post-lithography cleaning treatments are therefore needed. We report that mechanical cleaning based on contact mode atomic force mi

  6. Fuzziness in Quantum Mechanics

    CERN Document Server

    Granik, A

    1996-01-01

    It is shown that quantum mechanics can be regarded as what one might call a "fuzzy" mechanics whose underlying logic is the fuzzy one, in contradistinction to the classical "crisp" logic. Therefore classical mechanics can be viewed as a crisp limit of a "fuzzy" quantum mechanics. Based on these considerations it is possible to arrive at the Schroedinger equation directly from the Hamilton-Jacobi equation. The link between these equations is based on the fact that a unique ("crisp") trajectory of a classical particle emerges out of a continuum of possible paths collapsing to a single trajectory according to the principle of least action. This can be interpreted as a consequence of an assumption that a quantum "particle" "resides" in every path of the continuum of paths which collapse to a single(unique) trajectory of an observed classical motion. A wave function then is treated as a function describing a deterministic entity having a fuzzy character. As a consequence of such an interpretation, the complimentar...

  7. Mechanisms of multidrug transporters

    NARCIS (Netherlands)

    Bolhuis, H; van Veen, H.W.; Poolman, B.; Driessen, A.J.M.; Konings, W.N

    1997-01-01

    Drug resistance, mediated by various mechanisms, plays a crucial role in the failure of the drug-based treatment of various infectious diseases. As a result, these infectious diseases re-emerge rapidly and cause many victims every year. Another serious threat is imposed by the development of multidr

  8. Flight Mechanics Symposium 1997

    Science.gov (United States)

    Walls, Donna M. (Editor)

    1997-01-01

    This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium. This symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude determination error analysis; attitude dynamics; and orbit decay and maneuver strategy. Government, industry, and the academic community participated in the preparation and presentation of these papers.

  9. Industrial Mechanical Maintenance.

    Science.gov (United States)

    Hendrix, Laborn J.

    This manual was developed to assist teachers in Oklahoma in preparing students for industrial mechanical maintenance. The materials in this teacher's guide are organized in 14 units of instruction covering the following four areas: receiving and setting equipment; equipment hookup and operation; equipment layout, anchoring, and setup; and…

  10. Mechanically Invisible Polymer Coatings

    DEFF Research Database (Denmark)

    2014-01-01

    phase comprises particles, said particles comprising a filler material and an encapsulating coating of a second polymeric material, wherein the backbones of the first and second polymeric materials are the same. The composition may be used in electroactive polymers (EAPs) in order to obtain mechanically...... invisible polymer coatings....

  11. Nonlinear tsunami generation mechanism

    Directory of Open Access Journals (Sweden)

    M. A. Nosov

    2001-01-01

    Full Text Available The nonlinear mechanism of long gravitational surface water wave generation by high-frequency bottom oscillations in a water layer of constant depth is investigated analytically. The connection between the surface wave amplitude and the parameters of bottom oscillations and source length is investigated.

  12. Classical Mechanics Laboratory

    Science.gov (United States)

    Brosing, Juliet W.

    2006-12-01

    At Pacific University we have included a lab with our upper division Classical Mechanics class. We do a combination of physical labs (air resistance, harmonic motion, amusement park physics), Maple labs (software), and projects. Presentation of some of the labs, results and challenges with this course will be included.

  13. Quantum Chaos and Statistical Mechanics

    OpenAIRE

    Srednicki, Mark

    1994-01-01

    We briefly review the well known connection between classical chaos and classical statistical mechanics, and the recently discovered connection between quantum chaos and quantum statistical mechanics.

  14. Mechanism for salt scaling

    Science.gov (United States)

    Valenza, John J., II

    Salt scaling is superficial damage caused by freezing a saline solution on the surface of a cementitious body. The damage consists of the removal of small chips or flakes of binder. The discovery of this phenomenon in the early 1950's prompted hundreds of experimental studies, which clearly elucidated the characteristics of this damage. In particular it was shown that a pessimum salt concentration exists, where a moderate salt concentration (˜3%) results in the most damage. Despite the numerous studies, the mechanism responsible for salt scaling has not been identified. In this work it is shown that salt scaling is a result of the large thermal expansion mismatch between ice and the cementitious body, and that the mechanism responsible for damage is analogous to glue-spalling. When ice forms on a cementitious body a bi-material composite is formed. The thermal expansion coefficient of the ice is ˜5 times that of the underlying body, so when the temperature of the composite is lowered below the melting point, the ice goes into tension. Once this stress exceeds the strength of the ice, cracks initiate in the ice and propagate into the surface of the cementitious body, removing a flake of material. The glue-spall mechanism accounts for all of the characteristics of salt scaling. In particular, a theoretical analysis is presented which shows that the pessimum concentration is a consequence of the effect of brine pockets on the mechanical properties of ice, and that the damage morphology is accounted for by fracture mechanics. Finally, empirical evidence is presented that proves that the glue-small mechanism is the primary cause of salt scaling. The primary experimental tool used in this study is a novel warping experiment, where a pool of liquid is formed on top of a thin (˜3 mm) plate of cement paste. Stresses in the plate, including thermal expansion mismatch, result in warping of the plate, which is easily detected. This technique revealed the existence of

  15. Quantum Mechanics As A Limiting Case of Classical Mechanics

    OpenAIRE

    Ghose, Partha

    2000-01-01

    In spite of its popularity, it has not been possible to vindicate the conventional wisdom that classical mechanics is a limiting case of quantum mechanics. The purpose of the present paper is to offer an alternative point of view in which quantum mechanics emerges as a limiting case of classical mechanics in which the classical system is decoupled from its environment.

  16. Pragmatic Mechanism of Homonym

    Institute of Scientific and Technical Information of China (English)

    马群英; 王亚辉

    2014-01-01

    Words, derivation of symbols, are a part played in human affairs by language of all kinds, and especially of their influ⁃ence on thought. According to The Triangle of Reference, words/symbols are endowed with references, some of which are one-on-one connected, and some of which are one-on-multiple colligated, modulated by social convention. Phenomena of using homonym are ubiquitous while the system of using it is still opaque. The multiple meaning of homonym is considered to have a pragmatic mechanism in which the implementing process of utterer and the construing pattern of hearer are regulated and formu⁃lated. This paper is tentatively cogitating polysemy in a system of pragmatic utility and tabling a pragmatic mechanism of hom⁃onym for better understanding and academic contribution of it.

  17. Responding to Mechanical Antigravity

    Science.gov (United States)

    Millis, Marc G.; Thomas, Nicholas E.

    2006-01-01

    Based on the experiences of the NASA Breakthrough Propulsion Physics Project, suggestions are offered for constructively responding to proposals that purport breakthrough propulsion using mechanical devices. Because of the relatively large number of unsolicited submissions received (about 1 per workday) and because many of these involve similar concepts, this report is offered to help the would-be submitters make genuine progress as well as to help reviewers respond to such submissions. Devices that use oscillating masses or gyroscope falsely appear to create net thrust through differential friction or by misinterpreting torques as linear forces. To cover both the possibility of an errant claim and a genuine discovery, reviews should require that submitters meet minimal thresholds of proof before engaging in further correspondence; such as achieving sustained deflection of a level-platform pendulum in the case of mechanical thrusters.

  18. Immunosuppressive mechanisms in glioblastoma.

    Science.gov (United States)

    Nduom, Edjah K; Weller, Michael; Heimberger, Amy B

    2015-11-01

    Despite maximal surgical and medical therapy, the treatment of glioblastoma remains a seriously vexing problem, with median survival well under 2 years and few long-term survivors. Targeted therapy has yet to produce significant advances in treatment of these lesions in spite of advanced molecular characterization of glioblastoma and glioblastoma cancer stem cells. Recently, immunotherapy has emerged as a promising mode for some of the hardest to treat tumors, including metastatic melanoma. Although immunotherapy has been evaluated in glioblastoma in the past with limited success, better understanding of the failures of these therapies could lead to more successful treatments in the future. Furthermore, there is a persistent challenge for the use of immune therapy to treat glioblastoma secondary to the existence of redundant mechanisms of tumor-mediated immune suppression. Here we will address these mechanisms of immunosuppression in glioblastoma and therapeutic approaches.

  19. Hierarchical auxetic mechanical metamaterials.

    Science.gov (United States)

    Gatt, Ruben; Mizzi, Luke; Azzopardi, Joseph I; Azzopardi, Keith M; Attard, Daphne; Casha, Aaron; Briffa, Joseph; Grima, Joseph N

    2015-02-11

    Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.

  20. Mechanics of Wood Machining

    CERN Document Server

    Csanády, Etele

    2013-01-01

    Wood is one of the most valuable materials for mankind, and since our earliest days wood materials have been widely used. Today we have modern woodworking machine and tools; however, the raw wood materials available are continuously declining. Therefore we are forced to use this precious material more economically, reducing waste wherever possible. This new textbook on the “Mechanics of Wood Machining” combines the quantitative, mathematical analysis of the mechanisms of wood processing with practical recommendations and solutions. Bringing together materials from many sources, the book contains new theoretical and experimental approaches and offers a clear and systematic overview of the theory of wood cutting, thermal loading in wood-cutting tools, dynamic behaviour of tool and work piece, optimum choice of operational parameters and energy consumption, the wear process of the tools, and the general regularities of wood surface roughness. Diagrams are provided for the quick estimation of various process ...

  1. Origami based Mechanical Metamaterials

    Science.gov (United States)

    Lv, Cheng; Krishnaraju, Deepakshyam; Konjevod, Goran; Yu, Hongyu; Jiang, Hanqing

    2014-01-01

    We describe mechanical metamaterials created by folding flat sheets in the tradition of origami, the art of paper folding, and study them in terms of their basic geometric and stiffness properties, as well as load bearing capability. A periodic Miura-ori pattern and a non-periodic Ron Resch pattern were studied. Unexceptional coexistence of positive and negative Poisson's ratio was reported for Miura-ori pattern, which are consistent with the interesting shear behavior and infinity bulk modulus of the same pattern. Unusually strong load bearing capability of the Ron Resch pattern was found and attributed to the unique way of folding. This work paves the way to the study of intriguing properties of origami structures as mechanical metamaterials. PMID:25099402

  2. Photovoltaic array loss mechanisms

    Science.gov (United States)

    Gonzalez, Charles

    1986-10-01

    Loss mechanisms which come into play when solar cell modules are mounted in arrays are identified. Losses can occur either from a reduction in the array electrical performance or with nonoptimal extraction of power from the array. Electrical performance degradation is caused by electrical mismatch, transmission losses from cell surface soiling and steep angle of reflectance, and electrical losses from field wiring resistance and the voltage drop across blocking diodes. The second type of loss, concerned with the operating points of the array, can involve nonoptimal load impedance and limiting the operating envelope of the array to specific ranges of voltage and current. Each of the loss mechanisms are discussed and average energy losses expected from soiling, steep reflectance angles and circuit losses are calculated.

  3. Modelling Cochlear Mechanics

    Directory of Open Access Journals (Sweden)

    Guangjian Ni

    2014-01-01

    Full Text Available The cochlea plays a crucial role in mammal hearing. The basic function of the cochlea is to map sounds of different frequencies onto corresponding characteristic positions on the basilar membrane (BM. Sounds enter the fluid-filled cochlea and cause deflection of the BM due to pressure differences between the cochlear fluid chambers. These deflections travel along the cochlea, increasing in amplitude, until a frequency-dependent characteristic position and then decay away rapidly. The hair cells can detect these deflections and encode them as neural signals. Modelling the mechanics of the cochlea is of help in interpreting experimental observations and also can provide predictions of the results of experiments that cannot currently be performed due to technical limitations. This paper focuses on reviewing the numerical modelling of the mechanical and electrical processes in the cochlea, which include fluid coupling, micromechanics, the cochlear amplifier, nonlinearity, and electrical coupling.

  4. Mechanisms of intergranular fracture

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, D. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering

    1999-08-01

    The authors present a study of the atomistic mechanisms of crack propagation along grain boundaries in metals and alloys. The failure behavior showing cleavage crack growth and/or crack-tip dislocation emission is demonstrated using atomistic simulations for an embedded-atom model. The simulations follow the quasi-equilibrium growth of a crack as the stress intensity applied increases. Dislocations emitted from crack tips normally blunt the crack and inhibit cleavage, inducing ductile behavior. When the emitted dislocations stay near the crack tip (sessile dislocations), they do blunt the crack but brittle cleavage can occur after the emission of a sufficient number of dislocations. The fracture process occurs as a combination of dislocation emission/micro-cleavage portions that are controlled by the local atomistic structure of the grain boundary. The grain boundary is shown to be a region where dislocation emission is easier, a mechanism that competes with the lower cohesive strength of the boundary region.

  5. NUT SCREW MECHANISMS

    Science.gov (United States)

    Glass, J.A.F.

    1958-07-01

    A reactor control mechanism is described wherein the control is achieved by the partial or total withdrawal of the fissile material which is in the form of a fuel rod. The fuel rod is designed to be raised and lowered from the reactor core area by means of two concentric ball nut and screw assemblies that may telescope one within the other. These screw mechanisms are connected through a magnetic clutch to a speed reduction gear and an accurately controllable prime motive source. With the clutch energized, the fuel rod may be moved into the reactor core area, and fine adjustments may be made through the reduction gearing. However, in the event of a power failure or an emergency signal, the magnetic clutch will become deenergized, and the fuel rod will drop out of the core area by the force of gravity, thus shutting down the operation of the reactor.

  6. Relativistic quantum mechanics

    CERN Document Server

    Wachter, Armin

    2010-01-01

    Which problems do arise within relativistic enhancements of the Schrödinger theory, especially if one adheres to the usual one-particle interpretation, and to what extent can these problems be overcome? And what is the physical necessity of quantum field theories? In many books, answers to these fundamental questions are given highly insufficiently by treating the relativistic quantum mechanical one-particle concept very superficially and instead introducing field quantization as soon as possible. By contrast, this monograph emphasizes relativistic quantum mechanics in the narrow sense: it extensively discusses relativistic one-particle concepts and reveals their problems and limitations, therefore motivating the necessity of quantized fields in a physically comprehensible way. The first chapters contain a detailed presentation and comparison of the Klein-Gordon and Dirac theory, always in view of the non-relativistic theory. In the third chapter, we consider relativistic scattering processes and develop the...

  7. Determinism beneath Quantum Mechanics

    CERN Document Server

    Hooft, G

    2002-01-01

    Contrary to common belief, it is not difficult to construct deterministic models where stochastic behavior is correctly described by quantum mechanical amplitudes, in precise accordance with the Copenhagen-Bohr-Bohm doctrine. What is difficult however is to obtain a Hamiltonian that is bounded from below, and whose ground state is a vacuum that exhibits complicated vacuum fluctuations, as in the real world. Beneath Quantum Mechanics, there may be a deterministic theory with (local) information loss. This may lead to a sufficiently complex vacuum state, and to an apparent non-locality in the relation between the deterministic ("ontological") states and the quantum states, of the kind needed to explain away the Bell inequalities. Theories of this kind would not only be appealing from a philosophical point of view, but may also be essential for understanding causality at Planckian distance scales.

  8. Imaging the Antikythera Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Malzbender, Thomas

    2012-02-10

    In 1900, a party of sponge divers chanced on the wreck of a Roman merchant vessel between Crete and mainland Greece. It was found to contain numerous ancient Greek treasures, among them a mysterious lump of clay that split open to reveal ‘mathematical gears’ as it dried out. This object is now known as the Antikythera Mechanism, one of the most enlightening artifacts in terms of revealing the advanced nature of ancient Greek science and technology. In 2005 we travelled to the National Archeological Museum in Athens to apply our Reflectance Imaging methods to the mechanism in the hopes of revealing ancient writing on the device. We were successful, and along with the results of Microfocus CT imaging, epigraphers were able to decipher 3000 characters.

  9. Time in quantum mechanics

    CERN Document Server

    Mayato, R; Egusquiza, I

    2002-01-01

    The treatment of time in quantum mechanics is still an important and challenging open question in the foundation of the theory. This book describes the problems, and the attempts and achievements in defining, formalizing and measuring different time quantities in quantum theory, such as the parametric (clock) time, tunneling times, decay times, dwell times, delay times, arrival times or jump times. This multiauthored book, written as an introductory guide for the non-initiated as well as a useful source of information for the expert, covers many of the open questions. A brief historical overview is to be found in the introduction. It is followed by 12 chapters devoted to conceptual and theoretical investigations as well as experimental issues in quantum-mechanical time measurements. This unique monograph should attract physicists as well as philosophers of science working in the foundations of quantum physics.

  10. Ventilation and respiratory mechanics.

    Science.gov (United States)

    Sheel, Andrew William; Romer, Lee M

    2012-04-01

    During dynamic exercise, the healthy pulmonary system faces several major challenges, including decreases in mixed venous oxygen content and increases in mixed venous carbon dioxide. As such, the ventilatory demand is increased, while the rising cardiac output means that blood will have considerably less time in the pulmonary capillaries to accomplish gas exchange. Blood gas homeostasis must be accomplished by precise regulation of alveolar ventilation via medullary neural networks and sensory reflex mechanisms. It is equally important that cardiovascular and pulmonary system responses to exercise be precisely matched to the increase in metabolic requirements, and that the substantial gas transport needs of both respiratory and locomotor muscles be considered. Our article addresses each of these topics with emphasis on the healthy, young adult exercising in normoxia. We review recent evidence concerning how exercise hyperpnea influences sympathetic vasoconstrictor outflow and the effect this might have on the ability to perform muscular work. We also review sex-based differences in lung mechanics.

  11. Hierarchical Auxetic Mechanical Metamaterials

    Science.gov (United States)

    Gatt, Ruben; Mizzi, Luke; Azzopardi, Joseph I.; Azzopardi, Keith M.; Attard, Daphne; Casha, Aaron; Briffa, Joseph; Grima, Joseph N.

    2015-02-01

    Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.

  12. Mechanisms of mercury bioremediation.

    Science.gov (United States)

    Essa, A M M; Macaskie, L E; Brown, N L

    2002-08-01

    Mercury is one of the most toxic heavy metals, and has significant industrial and agricultural uses. These uses have led to severe localized mercury pollution. Mercury volatilization after its reduction to the metallic form by mercury-resistant bacteria has been reported as a mechanism for mercury bioremediation [Brunke, Deckwer, Frischmuth, Horn, Lunsdorf, Rhode, Rohricht, Timmis and Weppen (1993) FEMS Microbiol. Rev. 11, 145-152; von Canstein, Timmis, Deckwer and Wagner-Dobler (1999) Appl. Environ. Microbiol. 65, 5279-5284]. The reduction/volatilization system requires to be studied further, in order to eliminate the escape of the metallic mercury into the environment. Recently we have demonstrated three different mechanisms for mercury detoxification in one organism, Klebsiella pneumoniae M426, which may increase the capture efficiency of mercury.

  13. New quantum mechanical model

    Institute of Scientific and Technical Information of China (English)

    吴宁; 阮图南

    1996-01-01

    A quantum mechanical model with one bosonic degree of freedom is discussed in detail. Conventionally, when a quantum mechanical model is constructed, one must know the corresponding classical model. And by applying the correspondence between the classical Poisson brackets and the canonical commutator, the canonical quantization condition can be obtained. In the quantum model, study of the corresponding classical model is needed first. In this model, the Lagrangian is an operator gauge invariant. After localization, in order to keep gauge invariance, the operator gauge potential must be introduced. The Eular-Lagrange equation of motion of the dynamical argument gives the usual operator equation of motion. And the operator gauge potential just gjves a constraint. This constraint is just the usual canonical quantization condition.

  14. Mechanics of collective unfolding

    CERN Document Server

    Caruel, M; Truskinovsky, L

    2015-01-01

    Mechanically induced unfolding of passive crosslinkers is a fundamental biological phenomenon encountered across the scales from individual macro-molecules to cytoskeletal actin networks. In this paper we study a conceptual model of athermal load-induced unfolding and use a minimalistic setting allowing one to emphasize the role of long-range interactions while maintaining full analytical transparency. Our model can be viewed as a description of a parallel bundle of N bistable units confined between two shared rigid backbones that are loaded through a series spring. We show that the ground states in this model correspond to synchronized, single phase configurations where all individual units are either folded or unfolded. We then study the fine structure of the wiggly energy landscape along the reaction coordinate linking the two coherent states and describing the optimal mechanism of cooperative unfolding. Quite remarkably, our study shows the fundamental difference in the size and structure of the folding-u...

  15. Crude oil burning mechanisms

    DEFF Research Database (Denmark)

    van Gelderen, Laurens; Malmquist, Linus Mattias Valdemar; Jomaas, Grunde

    2015-01-01

    In order to improve predictions for the burning efficiency and the residue composition of in-situ burning of crude oil, the burning mechanism of crude oil was studied in relation to the composition of its hydrocarbon mixture, before, during and after the burning. The surface temperature, flame...... height, mass loss rate and residues of three hydrocarbon liquids (n-octane, dodecane and hexadecane), two crude oils (DUC and REBCO) and one hydrocarbon liquid mixture of the aforementioned hydrocarbon liquids were studied using the Crude Oil Flammability Apparatus. The experimental results were compared...... to the predictions of four conceptual models that describe the burning mechanism of multicomponent fuels. Based on the comparisons, hydrocarbon liquids were found to be best described by the Equilibrium Flash Vaporization model, showing a constant gas composition and gasification rate. The multicomponent fuels...

  16. Computation in Classical Mechanics

    CERN Document Server

    Timberlake, Todd

    2007-01-01

    There is a growing consensus that physics majors need to learn computational skills, but many departments are still devoid of computation in their physics curriculum. Some departments may lack the resources or commitment to create a dedicated course or program in computational physics. One way around this difficulty is to include computation in a standard upper-level physics course. An intermediate classical mechanics course is particularly well suited for including computation. We discuss the ways we have used computation in our classical mechanics courses, focusing on how computational work can improve students' understanding of physics as well as their computational skills. We present examples of computational problems that serve these two purposes. In addition, we provide information about resources for instructors who would like to include computation in their courses.

  17. MECHANISMS OF BACTERIAL POLYHOSTALITY

    Directory of Open Access Journals (Sweden)

    Markova Yu.A.

    2007-12-01

    Full Text Available In the review data about factors of pathogenicity of the bacteria, capable to amaze both animals, and a plant are collected. Such properties of microorganisms as adhesion, secretion of some enzymes, mobility, a phenomenon of cooperative sensitivity - play an essential role at defeat of different organisms. They are used for many universal offensive strategy overcoming protection of an organism, irrespective of its evolutionary origin. Studying of these mechanisms, will allow to provide new approaches to monitoring illnesses.

  18. Mechanisms in Impact Fragmentation

    OpenAIRE

    Wittel, Falk K.; Carmona, Humberto A.; Kun, Ferenc; Herrmann, Hans J.

    2015-01-01

    The brittle fragmentation of spheres is studied numerically by a 3D Discrete Element Model. Large scale computer simulations are performed with models that consist of agglomerates of many spherical particles, interconnected by beam-truss elements. We focus on a detailed description of the fragmentation process and study several fragmentation mechanisms involved. The evolution of meridional cracks is studied in detail. These cracks are found to initiate in the inside of the specimen with quasi...

  19. DARPA's Big Mechanism program.

    Science.gov (United States)

    Cohen, Paul R

    2015-07-16

    Reductionist science produces causal models of small fragments of complicated systems. Causal models of entire systems can be hard to construct because what is known of them is distributed across a vast amount of literature. The Big Mechanism program aims to have machines read the literature and assemble the causal fragments found in individual papers into huge causal models, automatically. The current domain of the program is cell signalling associated with Ras-driven cancers.

  20. Riskfactors and underlying mechanisms

    OpenAIRE

    2015-01-01

    Childhood interpersonal traumatizations increase the risk for revictimizations as well as for psychological disorders like the posttraumatic stress disorder (PTSD). Different variables and mechanisms underlying revictimization are discussed in current literature. However, empiri-cal data on revictimization is poor and inconsistant. Guilt and shame following traumatic events are considered as risk factors for the development and persistence of PTSD. PTSD is frequently associated with trauma-re...

  1. Effectively calculable quantum mechanics

    OpenAIRE

    Bolotin, Arkady

    2015-01-01

    According to mathematical constructivism, a mathematical object can exist only if there is a way to compute (or "construct") it; so, what is non-computable is non-constructive. In the example of the quantum model, whose Fock states are associated with Fibonacci numbers, this paper shows that the mathematical formalism of quantum mechanics is non-constructive since it permits an undecidable (or effectively impossible) subset of Hilbert space. On the other hand, as it is argued in the paper, if...

  2. DARPA's Big Mechanism program

    Science.gov (United States)

    Cohen, Paul R.

    2015-07-01

    Reductionist science produces causal models of small fragments of complicated systems. Causal models of entire systems can be hard to construct because what is known of them is distributed across a vast amount of literature. The Big Mechanism program aims to have machines read the literature and assemble the causal fragments found in individual papers into huge causal models, automatically. The current domain of the program is cell signalling associated with Ras-driven cancers.

  3. [Multiple mechanisms of depression].

    Science.gov (United States)

    Liu, Chun-Lin; Ruan, Ke-Feng; Gao, Jun-Wei; Wu, Fei; Zhang, Ji-Quan

    2013-08-01

    Depression is a grievous mental disease with an increasing high morbidity year by year and a serious social harm. The pathogenesises of depression is complicated and involves with multi-mechanisms and multi-organs. Recent studies demondtrate that in the nerval system and endocrine system there are many types of neurotransmitters and hormones, as well as their receptors, involved in depression. This paper reviews the research progress of depression in recent years.

  4. Mechanisms of Coronal Heating

    Indian Academy of Sciences (India)

    S. R. Verma

    2006-06-01

    The Sun is a mysterious star. The high temperature of the chromosphere and corona present one of the most puzzling problems of solar physics. Observations show that the solar coronal heating problem is highly complex with many different facts. It is likely that different heating mechanisms are at work in solar corona. Recent observations show that Magnetic Carpet is a potential candidate for solar coronal heating.

  5. Mechanisms of Phosphine Toxicity

    OpenAIRE

    Nisa S. Nath; Ishita Bhattacharya; Andrew G. Tuck; Schlipalius, David I.; Paul R. Ebert

    2011-01-01

    Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH3), the chemistry of phosphorus is central to its toxicity...

  6. Probability in quantum mechanics

    Directory of Open Access Journals (Sweden)

    J. G. Gilson

    1982-01-01

    Full Text Available By using a fluid theory which is an alternative to quantum theory but from which the latter can be deduced exactly, the long-standing problem of how quantum mechanics is related to stochastic processes is studied. It can be seen how the Schrödinger probability density has a relationship to time spent on small sections of an orbit, just as the probability density has in some classical contexts.

  7. 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

  8. Symmetry and quantum mechanics

    CERN Document Server

    Corry, Scott

    2016-01-01

    This book offers an introduction to quantum mechanics for professionals, students, and others in the field of mathematics who have a minimal background in physics with an understanding of linear algebra and group theory. It covers such topics as Lie groups, algebras and their representations, and analysis (Hilbert space, distributions, the spectral Theorem, and the Stone-Von Neumann Theorem). The book emphasizes the role of symmetry and is useful to physicists as it provides a mathematical introduction to the topic.

  9. 1999 Flight Mechanics Symposium

    Science.gov (United States)

    Lynch, John P. (Editor)

    1999-01-01

    This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on May 18-20, 1999. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude determination error analysis; attitude dynamics; and orbit decay and maneuver strategy. Government, industry, and the academic community participated in the preparation and presentation of these papers.

  10. What Kind of Mechanism

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ Yang: In recent years, under the new international security environment, multilateralism has gradually played greater roles in various international and regional topics, especially in the settlement of regional security issues. Theoretically, regional multi-lateral security cooperation can increase the cost of destroying the status quo or invasion while increasing mutual confidence, alleviating feeling of security threat, decreasing or eliminating security predicament. This is caused by the limitations of the mechanism and the consideration of cost.

  11. Statistical mechanics and fractals

    CERN Document Server

    Dobrushin, Roland Lvovich

    1993-01-01

    This book is composed of two texts, by R.L. Dobrushin and S. Kusuoka, each representing the content of a course of lectures given by the authors. They are pitched at graduate student level and are thus very accessible introductions to their respective subjects for students and non specialists. CONTENTS: R.L. Dobrushin: On the Way to the Mathematical Foundations of Statistical Mechanics.- S. Kusuoka: Diffusion Processes on Nested Fractals.

  12. Mechanics in medicine

    OpenAIRE

    Bao, Gang; Bazilevs, Yuri; Chung, Jae-Hyun; Decuzzi,Paolo; Espinosa, Horacio D.; Ferrari, Mauro; Gao, Huajian; Hossain, Shaolie S.; Hughes, Thomas J. R.; Kamm, Roger Dale; Liu, Wing Kam; Marsden, Alison; Schrefler, Bernhard

    2014-01-01

    Over decades, the theoretical and applied mechanics community has developed sophisticated approaches for analysing the behaviour of complex engineering systems. Most of these approaches have targeted systems in the transportation, materials, defence and energy industries. Applying and further developing engineering approaches for understanding, predicting and modulating the response of complicated biomedical processes not only holds great promise in meeting societal needs, but also poses seri...

  13. Design on hopping locomotion mechanism

    Institute of Scientific and Technical Information of China (English)

    LU Yong-kui; WU Yue-hua; YANG Jie; Hisayuki AOYAMA

    2005-01-01

    A new type of locomotion mechanism is introduced in this paper. With vibrating motors used in controling the movement of the hopping locomotion mechanism, the simple hopping locomotion mechanism had two motors, when the current went through the vertical motor, the vertical motor would vibrate to cause the mechanism to go forward, and when the current went through the horizontal motor, the mechanism will go around itself. A spring was added to the mechanism to change the natural frequency of the mechanism, when the frequency of the motor was equal to the natural frequency of the mechanism, the mechanism would hop resonantly. With the resonant hopping, the load of the mechanism was greatly enlarged, and some sensors could be added to the mechanism. Optical sensors were used to detect the infrared source, the current that went through the sensors related to the distance between the infrared light. Three optical sensors was put on the left, right and the front the mechanism, when the mechanism detect the special infrared source, it would turn itself to the light, and go forward to the light. The experiments of the mechanism shown that the mechanism could work well on different surfaces freely, and the resonant hopping locomotion mechanism with infrared sensors could move to the special light by automatic regulation. Experimental results and theoretical studies demonstrate that the innovative design for hopping locomotion mechanism is superior.

  14. Time Asymmetric Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Arno R. Bohm

    2011-09-01

    Full Text Available The meaning of time asymmetry in quantum physics is discussed. On the basis of a mathematical theorem, the Stone-von Neumann theorem, the solutions of the dynamical equations, the Schrödinger equation (1 for states or the Heisenberg equation (6a for observables are given by a unitary group. Dirac kets require the concept of a RHS (rigged Hilbert space of Schwartz functions; for this kind of RHS a mathematical theorem also leads to time symmetric group evolution. Scattering theory suggests to distinguish mathematically between states (defined by a preparation apparatus and observables (defined by a registration apparatus (detector. If one requires that scattering resonances of width Γ and exponentially decaying states of lifetime τ=h/Γ should be the same physical entities (for which there is sufficient evidence one is led to a pair of RHS's of Hardy functions and connected with it, to a semigroup time evolution t_0≤t<∞, with the puzzling result that there is a quantum mechanical beginning of time, just like the big bang time for the universe, when it was a quantum system. The decay of quasi-stable particles is used to illustrate this quantum mechanical time asymmetry. From the analysis of these processes, we show that the properties of rigged Hilbert spaces of Hardy functions are suitable for a formulation of time asymmetry in quantum mechanics.

  15. Mechanical Properties of Materials

    CERN Document Server

    Pelleg, Joshua

    2013-01-01

    The subject of mechanical behavior has been in the front line of basic studies in engineering curricula for many years.  This textbook was written for engineering students with the aim of presenting, in a relatively simple manner, the basic concepts of mechanical behavior in solid materials. A second aim of the book is to guide students in their laboratory experiments by helping them to understand their observations in parallel with the lectures of their various courses; therefore the first chapter of the book is devoted to mechanical testing. Another aim of the book is to provide practicing engineers with basic help to bridge the gap of time that has passed from their graduation up to their actual involvement in engineering work. The book also serves as the basis for more advanced studies and seminars when pursuing courses on a graduate level. The content of this textbook and the topics discussed correspond to courses that are usually taught in universities and colleges all over the world, but with a differ...

  16. Copenhagen quantum mechanics

    Science.gov (United States)

    Hollowood, Timothy J.

    2016-07-01

    In our quantum mechanics courses, measurement is usually taught in passing, as an ad-hoc procedure involving the ugly collapse of the wave function. No wonder we search for more satisfying alternatives to the Copenhagen interpretation. But this overlooks the fact that the approach fits very well with modern measurement theory with its notions of the conditioned state and quantum trajectory. In addition, what we know of as the Copenhagen interpretation is a later 1950s development and some of the earlier pioneers like Bohr did not talk of wave function collapse. In fact, if one takes these earlier ideas and mixes them with later insights of decoherence, a much more satisfying version of Copenhagen quantum mechanics emerges, one for which the collapse of the wave function is seen to be a harmless book keeping device. Along the way, we explain why chaotic systems lead to wave functions that spread out quickly on macroscopic scales implying that Schrödinger cat states are the norm rather than curiosities generated in physicists' laboratories. We then describe how the conditioned state of a quantum system depends crucially on how the system is monitored illustrating this with the example of a decaying atom monitored with a time of arrival photon detector, leading to Bohr's quantum jumps. On the other hand, other kinds of detection lead to much smoother behaviour, providing yet another example of complementarity. Finally we explain how classical behaviour emerges, including classical mechanics but also thermodynamics.

  17. Graduate Quantum Mechanics Reform

    CERN Document Server

    Carr, L D

    2008-01-01

    We address four main areas in which graduate quantum mechanics education in the U.S. can be improved: course content; textbook; teaching methods; and assessment tools. We report on a three year longitudinal study at the Colorado School of Mines using innovations in all four of these areas. In particular, we have modified the content of the course to reflect progress in the field in the last 50 years, use modern textbooks that include such content, incorporate a variety of teaching techniques based on physics education research, and used a variety of assessment tools to study the effectiveness of these reforms. We present a new assessment tool, the Graduate Quantum Mechanics Conceptual Survey, and further testing of a previously developed assessment tool, the Quantum Mechanics Conceptual Survey (QMCS). We find that graduate students respond well to research-based techniques that have previously been tested mainly in introductory courses, and that they learn a great deal of the new content introduced in each ve...

  18. Mechanical Design of Spacecraft

    Science.gov (United States)

    1962-01-01

    In the spring of 1962, engineers from the Engineering Mechanics Division of the Jet Propulsion Laboratory gave a series of lectures on spacecraft design at the Engineering Design seminars conducted at the California Institute of Technology. Several of these lectures were subsequently given at Stanford University as part of the Space Technology seminar series sponsored by the Department of Aeronautics and Astronautics. Presented here are notes taken from these lectures. The lectures were conceived with the intent of providing the audience with a glimpse of the activities of a few mechanical engineers who are involved in designing, building, and testing spacecraft. Engineering courses generally consist of heavily idealized problems in order to allow the more efficient teaching of mathematical technique. Students, therefore, receive a somewhat limited exposure to actual engineering problems, which are typified by more unknowns than equations. For this reason it was considered valuable to demonstrate some of the problems faced by spacecraft designers, the processes used to arrive at solutions, and the interactions between the engineer and the remainder of the organization in which he is constrained to operate. These lecture notes are not so much a compilation of sophisticated techniques of analysis as they are a collection of examples of spacecraft hardware and associated problems. They will be of interest not so much to the experienced spacecraft designer as to those who wonder what part the mechanical engineer plays in an effort such as the exploration of space.

  19. The physio-mechanical

    Science.gov (United States)

    Atuanya, C. U.; Edokpia, R. O.; Aigbodion, V. S.

    This work presents a systematic approach to evaluate the physio-mechanical properties of bean pod ash particles (BPAp) reinforced recycled polyethylene (RLDPE) polymer based composites. The bean pod ash particles of 75 μm with a weight percentage of 0, 5, 10, 15, 20, 25, 30 (wt%) and recycled polyethylene (RLDPE) were prepared. The surface morphology, physical and the mechanical properties of the composites were examined. The results showed that the fair distribution of the bean pod ash particles in the microstructure of the polymer composites is the major factor responsible for the improvement in the mechanical properties. The bean pod ash particles added to the RLDPE polymer increased the percentage of water absorption and improved its rigidity, modulus and hardness values of the composites. The tensile and flexural strengths increased to a maximum of 20.1 and 39.0 N/mm2 at 20 wt% BPAp respectively. Based on the results obtained in this study, it is recommended that the composites can be used in the production of indoor and outdoor applications.

  20. Nonlinear cochlear mechanics.

    Science.gov (United States)

    Zweig, George

    2016-05-01

    An earlier paper characterizing the linear mechanical response of the organ of Corti [J. Acoust. Soc. Am. 138, 1102-1121 (2015)] is extended to the nonlinear domain. Assuming the existence of nonlinear oscillators nonlocally coupled through the pressure they help create, the oscillator equations are derived and examined when the stimuli are modulated tones and clicks. The nonlinearities are constrained by the requirements of oscillator stability and the invariance of zero crossings in the click response to changes in click amplitude. The nonlinear oscillator equations for tones are solved in terms of the fluid pressure that drives them, and its time derivative, presumably a proxy for forces created by outer hair cells. The pressure equation is reduced to quadrature, the integrand depending on the oscillators' responses. The resulting nonlocally coupled nonlinear equations for the pressure, and oscillator amplitudes and phases, are solved numerically in terms of the fluid pressure at the stapes. Methods for determining the nonlinear damping directly from measurements are described. Once the oscillators have been characterized from their tone and click responses, the mechanical response of the cochlea to natural sounds may be computed numerically. Signal processing inspired by cochlear mechanics opens up a new area of nonlocal nonlinear time-frequency analysis.

  1. Relativistic viscoelastic fluid mechanics.

    Science.gov (United States)

    Fukuma, Masafumi; Sakatani, Yuho

    2011-08-01

    A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

  2. Mechanical stop mechanism for overcoming MEMS fabrication tolerances

    Science.gov (United States)

    Hussein, Hussein; Bourbon, Gilles; Le Moal, Patrice; Haddab, Yassine; Lutz, Philippe

    2017-01-01

    A mechanical stop mechanism is developed in order to compensate MEMS fabrication tolerances in discrete positioning. The mechanical stop mechanism is designed to be implemented on SOI wafers using a common DRIE etching process. The various fabrication tolerances obtained due to the etching process are presented and discussed in the paper. The principle and design of the mechanism are then presented. Finally, experiments on microfabricated positioning prototypes show accurate steps unaffected by the fabrication tolerances.

  3. Mechanical stratigraphy and normal faulting

    Science.gov (United States)

    Ferrill, David A.; Morris, Alan P.; McGinnis, Ronald N.; Smart, Kevin J.; Wigginton, Sarah S.; Hill, Nicola J.

    2017-01-01

    Mechanical stratigraphy encompasses the mechanical properties, thicknesses, and interface properties of rock units. Although mechanical stratigraphy often relates directly to lithostratigraphy, lithologic description alone does not adequately describe mechanical behavior. Analyses of normal faults with displacements of millimeters to 10's of kilometers in mechanically layered rocks reveal that mechanical stratigraphy influences nucleation, failure mode, fault geometry, displacement gradient, displacement distribution, fault core and damage zone characteristics, and fault zone deformation processes. The relationship between normal faulting and mechanical stratigraphy can be used either to predict structural style using knowledge of mechanical stratigraphy, or conversely to interpret mechanical stratigraphy based on characterization of the structural style. This review paper explores a range of mechanical stratigraphic controls on normal faulting illustrated by natural and modeled examples.

  4. On Foundations of Newtonian Mechanics

    CERN Document Server

    Cheremensky, Al

    2010-01-01

    Being based on V. Konoplev's axiomatic approach to continuum mechanics, the paper broadens its frontiers in order to bring together continuum mechanics with classical mechanics in a new theory of mechanical systems. There are derived motion equations of `abstract' mechanical systems specified for mass-points, multibody systems and continua: Newton-Euler equations, Lagrange equations of II kind and Navier-Stokes ones. Quasi-linear constitutive equations are introduced in conformity with V. Konoplev's definition of stress and strain (rate) matrices.

  5. Craniofacial Pain: Brainstem Mechanisms

    Directory of Open Access Journals (Sweden)

    Barry J Sessle

    1996-01-01

    Full Text Available This article reviews recent research advances in animals that have identified critical neural elements in the brainstem receiving and transmitting craniofacial nociceptive inputs, as well as some of the mechanisms involved in the modulation and plasticity of nociceptive transmission. Nociceptive neurones in the trigeminal (V brainstem sensory nuclear complex can be classified as nociceptive-specific (NS or wide dynamic range (WDR. Some of these neurones respond exclusively to sensory inputs evoked by stimulation of facial skin or oral mucosa and have features suggesting that they are critical neural elements involved in the ability to localize an acute superficial pain and sense its intensity and duration. Many of the V brainstem nociceptive neurones, however, receive convergent inputs from afferents supplying deep craniofacial tissues (eg, dural vessel, muscle and skin or mucosa. These neurones are likely involved in deep pain, including headache, because few nociceptive neurones receive inputs exclusively from afferents supplying these tissues. These extensive convergent input patterns also appear to be important factors in pain spread and referral, and in central mechanisms underlying neuroplastic changes in V neuronal properties that may occur with injury and inflammation. For example, application of the small fibre excitant and inflammatory irritant mustard oil into the temporomandibular joint, masseter or tongue musculature induces a prolonged but reversible enhancement of responses to cutaneous and deep afferent inputs of most WDR and NS neurones. These effects may be accompanied by increased electromyographic activity reflexly induced in the masticatory muscles by mustard oil, and involve endogenous N-methyl-D-aspartate and opioid neurochemical mechanisms. Such peripherally induced modulation of brainstem nociceptive neuronal properties reflects the functional plasticity of the central V system, and may be involved in the development of

  6. Statistical mechanics of learning

    CERN Document Server

    Engel, Andreas

    2001-01-01

    The effort to build machines that are able to learn and undertake tasks such as datamining, image processing and pattern recognition has led to the development of artificial neural networks in which learning from examples may be described and understood. The contribution to this subject made over the past decade by researchers applying the techniques of statistical mechanics is the subject of this book. The authors provide a coherent account of various important concepts and techniques that are currently only found scattered in papers, supplement this with background material in mathematics and physics, and include many examples and exercises.

  7. Controlled mechanized trepan.

    Science.gov (United States)

    Kam, J; Goldratt, E M; Barishak, Y R; Stein, R

    1978-04-01

    A mechanized trepan is described whose cutting action is halted automatically when the trepan's cutting edge reaches the last 0.03 mm. tissue layer of the cornea. The automatic half of both the motor which advances the trepan as well as the second motor which rotates the trepan is triggered by the sudden change in electrical resistance between the trepan and the patient's internal body fluid, at the final stage of penetration. This automatic feature eliminates the danger of inadvertant damage to the inner structures of the eye.

  8. Analysis driven mechanical redesign

    Energy Technology Data Exchange (ETDEWEB)

    Ames, A.L.; Robison, R.H.

    1997-08-01

    This paper documents an effort to use a constrained nonlinear optimization package (OptdesX) to drive a feature-based mechanical design system (Pro/Engineer) in an optimization loop. Optimizations performed in this manner can maximally respect the design intent built into the model, and eliminate the need to propagate optimization results back to design, a flaw of most current optimization systems. A prototype system was built to demonstrate the capability; use of the prototype uncovered a variety of issues that should be addressed to productionize this kind of capability.

  9. 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

  10. Fracture mechanics safety approaches

    Energy Technology Data Exchange (ETDEWEB)

    Roos, E.; Schuler, X.; Eisele, U. [Materials Testing Inst. (MPA), Univ. of Stuttgart (Germany)

    2004-07-01

    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.)

  11. Mechanics of elastic composites

    CERN Document Server

    Cristescu, Nicolaie Dan; Soós, Eugen

    2003-01-01

    This is a comprehensive, reader-friendly treatment of the theory behind modern elastic composite materials. The treatment includes recently developed results and methods drawn from research papers published in Eastern Europe that until now were unavailable in many western countries. Among the book''s many notable features is the inclusion of more than 400 problems, many of which are solved at the end of the book. Mechanics of Elastic Composites is an outstanding textbook for graduate-level course work and a valuable reference for engineers and researchers. Developed over many years by leading

  12. Mechanics of materials model

    Science.gov (United States)

    Meister, Jeffrey P.

    1987-01-01

    The Mechanics of Materials Model (MOMM) is a three-dimensional inelastic structural analysis code for use as an early design stage tool for hot section components. MOMM is a stiffness method finite element code that uses a network of beams to characterize component behavior. The MOMM contains three material models to account for inelastic material behavior. These include the simplified material model, which assumes a bilinear stress-strain response; the state-of-the-art model, which utilizes the classical elastic-plastic-creep strain decomposition; and Walker's viscoplastic model, which accounts for the interaction between creep and plasticity that occurs under cyclic loading conditions.

  13. Mechanical engineering principles

    CERN Document Server

    Bird, John

    2014-01-01

    A student-friendly introduction to core engineering topicsThis book introduces mechanical principles and technology through examples and applications, enabling students to develop a sound understanding of both engineering principles and their use in practice. These theoretical concepts are supported by 400 fully worked problems, 700 further problems with answers, and 300 multiple-choice questions, all of which add up to give the reader a firm grounding on each topic.The new edition is up to date with the latest BTEC National specifications and can also be used on undergraduate courses in mecha

  14. Quantum mechanical Carnot engine

    CERN Document Server

    Bender, C M; Meister, B K

    2000-01-01

    A cyclic thermodynamic heat engine runs most efficiently if it is reversible. Carnot constructed such a reversible heat engine by combining adiabatic and isothermal processes for a system containing an ideal gas. Here, we present an example of a cyclic engine based on a single quantum-mechanical particle confined to a potential well. The efficiency of this engine is shown to equal the Carnot efficiency because quantum dynamics is reversible. The quantum heat engine has a cycle consisting of adiabatic and isothermal quantum processes that are close analogues of the corresponding classical processes.

  15. Mechanics of tissue compaction.

    Science.gov (United States)

    Turlier, Hervé; Maître, Jean-Léon

    2015-12-01

    During embryonic development, tissues deform by a succession and combination of morphogenetic processes. Tissue compaction is the morphogenetic process by which a tissue adopts a tighter structure. Recent studies characterized the respective roles of cells' adhesive and contractile properties in tissue compaction. In this review, we formalize the mechanical and molecular principles of tissue compaction and we analyze through the prism of this framework several morphogenetic events: the compaction of the early mouse embryo, the formation of the fly retina, the segmentation of somites and the separation of germ layers during gastrulation.

  16. 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...

  17. Molecular mechanisms in gliomagenesis

    DEFF Research Database (Denmark)

    Hulleman, Esther; Helin, Kristian

    2005-01-01

    brain development, such as the differentiation of neural stem cells (NSCs) into astrocytes, might contribute to GBM formation. These pathways include growth factor-induced signal transduction routes and processes that control cell cycle progression, such as the p16-CDK4-RB and the ARF-MDM2-p53 pathways....... The expression of several of the components of these signaling cascades has been found altered in GBM, and recent data indicate that combinations of mutations in these pathways may contribute to GBM formation, although the exact mechanisms are still to be uncovered. Use of novel techniques including large...

  18. 2001 Flight Mechanics Symposium

    Science.gov (United States)

    Lynch, John P. (Editor)

    2001-01-01

    This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on June 19-21, 2001. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to attitude/orbit determination, prediction and control; attitude simulation; attitude sensor calibration; theoretical foundation of attitude computation; dynamics model improvements; autonomous navigation; constellation design and formation flying; estimation theory and computational techniques; Earth environment mission analysis and design; and, spacecraft re-entry mission design and operations.

  19. Exactly Solvable Quantum Mechanics

    CERN Document Server

    Sasaki, Ryu

    2014-01-01

    A comprehensive review of exactly solvable quantum mechanics is presented with the emphasis of the recently discovered multi-indexed orthogonal polynomials. The main subjects to be discussed are the factorised Hamiltonians, the general structure of the solution spaces of the Schroedinger equation (Crum's theorem and its modifications), the shape invariance, the exact solvability in the Schroedinger picture as well as in the Heisenberg picture, the creation/annihilation operators and the dynamical symmetry algebras, coherent states, various deformation schemes (multiple Darboux transformations) and the infinite families of multi-indexed orthogonal polynomials, the exceptional orthogonal polynomials, and deformed exactly solvable scattering problems.

  20. Mechanism of nanofiber crimp

    Directory of Open Access Journals (Sweden)

    Chen Rou-Xi

    2013-01-01

    Full Text Available Fabrication of crimped fibers has been caught much attention recently due to remarkable improvement surface-to-volume ratio. The precise mechanism of the fiber crimp is, however, rare and preliminary. This paper finds that pulsation of fibers is the key factor for fiber crimp, and its configuration (wave formation corresponds to its nature frequency after solidification. Crimping performance can be improved by temperature control of the uncrimped fibers. In the paper, polylactide/ dimethylfomamide solution is fabricated into crimped nanofibers by the bubble electrospinning, an approximate period- amplitude relationship of the wave formation is obtained.

  1. Mechanics of artificial microcapsules

    Energy Technology Data Exchange (ETDEWEB)

    Fery, A; Dubreuil, F; Moehwald, H [Max-Planck Institute of Colloids and Interfaces, D 14424 Potsdam (Germany)

    2004-02-01

    In recent years, an increasing number of microcapsule systems have been realized and have found applications in various fields of research and technology. Amongst others, polyelectrolyte multilayer capsules (PMCs) offer a great variety of materials and superior control over the wall thicknesses. We present here a review on the different techniques that are available for characterizing the mechanical properties of PMCs. We compare results that were obtained using these techniques on the same system, namely PMCs made from polyallylamine and polystyrenesulfonate multilayers and discuss perspectives of the field.

  2. Nanoantenna using mechanical resonance

    KAUST Repository

    Chang Hwa Lee,

    2010-11-01

    Nanoantenna using mechanical resonance vibration is made from an indium tin oxide (ITO) coated vertically aligned nanorod array. Only this structure works as a radio with demodulator without any electrical circuit using field emission phenomenon. A top-down fabrication method of an ITO coated nanorod array is proposed using a modified UV lithography. The received radio frequency and the resonance frequency of nanoantenna can be controlled by the fabrication condition through the height of a nanorod array. The modulated signals are received successfully with the transmission carrier wave frequency (248MHz) and the proposed nanoantenna is expected to be used in communication system for ultra small scale sensor. ©2010 IEEE.

  3. Submicroscopic Deterministic Quantum Mechanics

    CERN Document Server

    Krasnoholovets, V

    2002-01-01

    So-called hidden variables introduced in quantum mechanics by de Broglie and Bohm have changed their initial enigmatic meanings and acquired quite reasonable outlines of real and measurable characteristics. The start viewpoint was the following: All the phenomena, which we observe in the quantum world, should reflect structural properties of the real space. Thus the scale 10^{-28} cm at which three fundamental interactions (electromagnetic, weak, and strong) intersect has been treated as the size of a building block of the space. The appearance of a massive particle is associated with a local deformation of the cellular space, i.e. deformation of a cell. The mechanics of a moving particle that has been constructed is deterministic by its nature and shows that the particle interacts with cells of the space creating elementary excitations called "inertons". The further study has disclosed that inertons are a substructure of the matter waves which are described by the orthodox wave \\psi-function formalism. The c...

  4. Mechanical engineering in hospitals.

    Science.gov (United States)

    Wallington, J W

    1980-10-01

    The design of a modern hospital owes more to engineering than the layman may realize. In this context, many engineers are in the position of laymen, being unfamiliar with the multitude of services that lies behind the impressive facade of a modern hospital. In recent years medicine and surgery themselves have taken on many of the characteristics of a technology. This has required a matching development of the services both mechanical and electrical that are required in modern health care buildings. In medical terms, if the architectural features provide the 'skin' of the hospital, the mechanical and electrical engineering services provide the nerves and sinews. If we take as an example the recently completed Freeman Hospital, Newcastle upon Tyne, (Fig. 1), which cost 10 million pounds at current cost, the service network was responsible for about half the total cost. About 400 miles (643 km) of electrical wiring and more than 40 mile (64.5 km) of copper and steel piping were used to service 3000 separate rooms. This compares with percentages of between 18 and 25 per cent for other large buildings such as office blocks, hotels and sports complexes.

  5. Particle acceleration mechanisms

    CERN Document Server

    Petrosyan, V

    2008-01-01

    We review the possible mechanisms for production of non-thermal electrons which are responsible for non-thermal radiation in clusters of galaxies. Our primary focus is on non-thermal Bremsstrahlung and inverse Compton scattering, that produce hard X-ray emission. We briefly review acceleration mechanisms and point out that in most astrophysical situations, and in particular for the intracluster medium, shocks, turbulence and plasma waves play a crucial role. We consider two scenarios for production of non-thermal radiation. The first is hard X-ray emission due to non-thermal Bremsstrahlung by nonrelativistic particles. Non-thermal tails are produced by accelerating electrons from the background plasma with an initial Maxwellian distribution. However, these tails are accompanied by significant heating and they are present for a short time of <10^6 yr, which is also the time that the tail will be thermalised. Such non-thermal tails, even if possible, can only explain the hard X-ray but not the radio emission...

  6. Lectures on Quantum Mechanics

    CERN Document Server

    Basdevant, Jean-Louis

    2007-01-01

    Beautifully illustrated and engagingly written, Lectures on Quantum Mechanics presents theoretical physics with a breathtaking array of examples and anecdotes. Basdevant's style is clear and stimulating, in the manner of a brisk classroom lecture that students can follow with ease and enjoyment. Here is a sample of the book's style, from the opening of Chapter 1: "If one were to ask a passer-by to quote a great formula of physics, chances are that the answer would be 'E = mc2'. Nevertheless, the formula 'E=hV' which was written in the same year 1905 by the same Albert Einstein, and which started quantum theory, concerns their daily life considerably more. In fact, of the three watershed years for physics toward the beginning of the 20th century - 1905: the Special Relativity of Einstein, Lorentz and Poincaré; 1915: the General Relativity of Einstein, with its extraordinary reflections on gravitation, space and time; and 1925: the full development of Quantum Mechanics - it is surely the last which has the mos...

  7. Thymoquinone: Novel gastroprotective mechanisms.

    Science.gov (United States)

    Magdy, Mahmoud-Awny; Hanan, El-Abhar; Nabila, El-Maraghy

    2012-12-15

    Ample of evidence proved the gastroprotective effect of thymoquinone (TQ), the main constituent of Nigella sativa oil; however, the full mechanistic cassette on the gastric ulcer etiopathogenesis is not fully elucidated. The aim of the present work is to unveil some of the possible mechanisms. Animals were injected with vehicle, TQ (10 & 20mg/kg), omeprazole (10 & 20mg/kg) or their combination (10mg/kg). Thirty minutes later, pyloric ligation was carried out and followed consequently with ischemia for another 30min, abided by reperfusion for 120min. The ischemia/reperfusion insult increased the gastric acid secretion, acid output, and pepsin, as well as the gastric mucosal content/activity of lipid peroxide, proton pump and myeloperoxidase, along with ulcer index. However, content/activity of gastric mucin, reduced glutathione, total nitric oxide, and superoxide dismutase were decreased. TQ, especially the high dose level, corrected the altered parameters in a comparable manner to that of the reference drug used, omeprazole. In addition, when the low doses were combined they add to each other to reach the effect of the high dose of either drug. These results showed that apart from its known antioxidant properties, TQ has novel gastroprotective mechanisms via inhibiting proton pump, acid secretion and neutrophil infiltration, while enhancing mucin secretion, and nitric oxide production.

  8. Peripheral Auditory Mechanisms

    CERN Document Server

    Hall, J; Hubbard, A; Neely, S; Tubis, A

    1986-01-01

    How weIl can we model experimental observations of the peripheral auditory system'? What theoretical predictions can we make that might be tested'? It was with these questions in mind that we organized the 1985 Mechanics of Hearing Workshop, to bring together auditory researchers to compare models with experimental observations. Tbe workshop forum was inspired by the very successful 1983 Mechanics of Hearing Workshop in Delft [1]. Boston University was chosen as the site of our meeting because of the Boston area's role as a center for hearing research in this country. We made a special effort at this meeting to attract students from around the world, because without students this field will not progress. Financial support for the workshop was provided in part by grant BNS- 8412878 from the National Science Foundation. Modeling is a traditional strategy in science and plays an important role in the scientific method. Models are the bridge between theory and experiment. Tbey test the assumptions made in experim...

  9. Elastomeric shutter mechanism

    Science.gov (United States)

    Curtis, Clifford M.

    1995-05-01

    An elastomeric shutter mechanism for opening and closing a passageway in the wall of a vessel, such as a submarine hull is presented. A single, unitary, retractable shutter member made of an elastomeric material is partially attached to the wall around a portion of a passageway. The single, unitary, retractable shutter member is moveable from a closed position when the unattached portion of the shutter member is abutting the wall around the passageway to an open position when the unattached portion of the shutter member is retracted away from the wall around the passageway. Cables are attached to the inside surface of the shutter member for retracting the shutter member and opening the passageway. Mechanical stops are positioned inside of the vessel for abutting the shutter member when retracted to the open position by the cables. On an underwater vessel such as a submarine, the shutter member is sealed in the closed position by a pressure differential between the inside surface and the outside surface of the shutter member or latched in place in the closed position. Split ribs are included on the inside surface of the shutter member to resist the expansion of the shutter member when maintained in the closed position by the pressure differential.

  10. Mechanical Properties of Cells

    Science.gov (United States)

    Bradley, Robert; Becerril, Joseph; Jeevarajan, Anthony

    2007-01-01

    Many physiologic and pathologic processes alter the biomechanical properties of the tissue they affect, and these changes may be manifest at the single cell level. The normal and abnormal mechanical properties of a given cell type can be established with the aid of an atomic force microscope (AFM), nonetheless, consistency in the area of the tip has been a mayor limitation of using the AFM for quantitative measurements of mechanical properties. This project attempts to overcome this limitation by using materials with a known elastic modulus, which resembles the one of the cell, to create force-deformation curves to calculate the area of indentation by means of Hooke s Law (sigma = E(epsilon)), which states that stress (sigma) is proportional to the strain (epsilon) where the constant of proportionality, E, is called the Young s modulus, also referred as the elastic modulus. Hook s Law can be rearranged to find the area of indentation (Area= Force/ E(epsilon)), where the indentation force is defined by the means of the added mass spring calibration method.

  11. Elements of Statistical Mechanics

    Science.gov (United States)

    Sachs, Ivo; Sen, Siddhartha; Sexton, James

    2006-05-01

    This textbook provides a concise introduction to the key concepts and tools of modern statistical mechanics. It also covers advanced topics such as non-relativistic quantum field theory and numerical methods. After introducing classical analytical techniques, such as cluster expansion and Landau theory, the authors present important numerical methods with applications to magnetic systems, Lennard-Jones fluids and biophysics. Quantum statistical mechanics is discussed in detail and applied to Bose-Einstein condensation and topics in astrophysics and cosmology. In order to describe emergent phenomena in interacting quantum systems, canonical non-relativistic quantum field theory is introduced and then reformulated in terms of Feynman integrals. Combining the authors' many years' experience of teaching courses in this area, this textbook is ideal for advanced undergraduate and graduate students in physics, chemistry and mathematics. Analytical and numerical techniques in one text, including sample codes and solved problems on the web at www.cambridge.org/0521841984 Covers a wide range of applications including magnetic systems, turbulence astrophysics, and biology Contains a concise introduction to Markov processes and molecular dynamics

  12. Reflections on FAC mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Lister, Derek H. [New Brunswick Univ., Fredericton, NB (Canada). Dept. of Chemical Engineering; Uchida, Shunsuke [Institute of Applied Energy, Tokyo (Japan)

    2010-10-15

    Flow-accelerated corrosion of carbon steel in steam-raising systems is obviously dominated by fluid-dynamic parameters such as turbulence and by water chemistry that promotes dissolution of the normally protective magnetite film; the mechanism is often formulated simply as the product of the mass transfer coefficient and the undersaturation in dissolved iron. Additives to the coolant, such as dissolved oxygen or ammonia, and elements in the steel, such as chromium, are then considered to inhibit flow-accelerated corrosion (FAC) by making the magnetite less soluble. This approach can be useful for predicting locations susceptible to FAC and for supporting proposals for palliative treatments, for example. It is rarely an accurate predictor of FAC rate, however, which may be attributable to its being applied in situations where surface reactions play a part. These issues are discussed in the light of recent research results and it is suggested that mechanisms introducing elements of mixed control may often be more appropriate. (orig.)

  13. Quantum mechanics of materials

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M.L.; Heine, V.; Phillips, J.C.

    1982-06-01

    In the past 25 years, new quantum-mechanical methods have been developed for predicting the configuration of the valence electrons in an atom or an aggregate of many atoms, within the range of energy excitations in which the atoms form interatomic bonds. A theory specifying the configuration of the valence electrons has much to say about the bulk properties of matter that depends on the nature of the interatomic bonds. The new method regards the core electrons and the atomic nucleus as if they constituted a single particle without internal structure. The method is called the pseudopotential theory. A general quantum-mechanical prediction of the properties of a substance in terms of the additive properties of separate chemical bonds is not yet feasible for molecules. However, there is one realm where prediction is now practical: crystalline solids. The regularity of the lattice into which the atoms are organized in a crystal makes it possible to calculate the properties of a macroscopic solid. In other words, many properties of an elemental solid such as lead or a simple binary solid such as gallium arsenide can not be deduced from energy considerations alone. (SC)

  14. Copenhagen Quantum Mechanics

    CERN Document Server

    Hollowood, Timothy J

    2015-01-01

    In our quantum mechanics courses, measurement is usually taught in passing, as an ad-hoc procedure involving the ugly collapse of the wave function. No wonder we search for more satisfying alternatives to the Copenhagen interpretation. But this overlooks the fact that the approach fits very well with modern measurement theory with its notions of the conditioned state and quantum trajectory. In addition, what we know of as the Copenhagen interpretation is a later 1950's development and some of the earlier pioneers like Bohr did not talk of wave function collapse. In fact, if one takes these earlier ideas and mixes them with later insights of decoherence, a much more satisfying version of Copenhagen quantum mechanics emerges, one for which the collapse of the wave function is seen to be a harmless book keeping device. Along the way, we explain why chaotic systems lead to wave functions that spread out quickly on macroscopic scales implying that Schrodinger cat states are the norm rather than curiosities generat...

  15. Clonus: definition, mechanism, treatment

    Directory of Open Access Journals (Sweden)

    Ismail Boyraz

    2015-02-01

    Full Text Available Clonus is involuntary and rhythmic muscle contractions caused by a permanent lesion in descending motor neurons. Clonus may be found at the ankle, patella, triceps surae, wrist, jaw, biceps brachii. In general, clonus may occur in any muscle with a frequency of 5-8 Hz and the average period of oscillations of the ankle clonus is approximately 160–200 ms. Plantar flexion (PF comprises 45% of the period, dorsifleksion (DF comprises 55% of the period. The first beat is always longer, with the time shortening in continuing beats and becoming stable in the 4th or 5th period. The exact mechanism of clonus remains unclear. Two different hypotheses have been asserted regarding the development of clonus. The most widely accepted explanation is that hyperactive stretch reflexes in clonus are caused by self-excitation. Another alternative explanation for clonus is central generator activity that arises as a consequence of appropriate peripheral events and produces rhythmic stimulation of the lower motor neurons. The durations of clonus burst were found longer than the durations of Soleus medium-latency reflex (MLR. There is a similarity in their nature, although the speed and cause of the stretch of triceps surae differ in the MLR and the clonus, and there is a sufficient period of time for group II afferents and for other spinal mechanisms to be involved in the clonus, together with Ia afferents. Clonus can be treated by using baclofen, applying cold, botox or phenol injections.

  16. [Antimicrobial mechanisms of action].

    Science.gov (United States)

    Calvo, Jorge; Martínez-Martínez, Luis

    2009-01-01

    A large number of families and groups of antimicrobial agents are of clinical interest. The mechanisms by which compounds with antibacterial activity inhibit growth or cause bacterial death are varied and depend on the affected targets. The bacterial cell wall-a unique structure in most bacteria that is absent in eukaryotic cells-can be affected in several ways: at different stages of synthesis (fosfomycin, cycloserine) or transport (bacitracin, mureidomycins) of its metabolic precursors, or by a direct action on its structural organization (beta-lactams, glycopeptides). The main drugs affecting the cytoplasmic membrane are polymyxins and daptomycin. Protein synthesis can be blocked by a large variety of compounds that affect any of the phases of this process, including activation (mupirocin), initiation (oxazolidinones, aminoglycosides), binding of the tRNA amino acid complex to ribosomes (tetracyclines, glycylcyclines) and elongation (amphenicols, lincosamides, macrolides, ketolides, streptogramins, fusidic acid). The metabolism of nucleic acids can be altered at the DNA-dependent RNA polymerase or in the process of DNA coiling (quinolones); some compounds affect DNA directly (nitroimidazoles, nitrofurans). Trimethoprim and sulfamides (often used in combination) are examples of antimicrobial agents that block bacterial metabolic pathways. Some compounds are unable to inhibit or kill bacteria in themselves, but can block bacterial mechanisms of resistance, enhancing the activity of other antimicrobials administered in combination. Among this group of agents, only certain beta-lactamase inhibitors are currently in clinical use.

  17. Nucleation Mechanism for Bainite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the experimental results that solute-depleted zone was observed in Cu-28Zn-4Al (mass fraction) at 523 K,△G is calculated as a positive according to the thermodynamic criteria for the spinodal decomposition of a ternarysystems. So, the solute-depleted zone cannot be formed by spinodal decomposition. Dislocation density requiredby the formation of solute-depleted zone is estimated greater than 7.89×109 cm-2 according to the segregationof solute atoms around dislocations, which is not consistent with the practical situation for the alloy at 523 K.Associated with the internal friction experimental fact that internal friction peaks appear within the incubation forbainitic transformation in Cu-Zn-Al alloy, the equilibrium temperature, T0, is evaluated as 433 K for solute-depletedCu-25Zn-3.4Al, which is lower than the experimental temperature 523 K. Thus, nucleation by shear mechanism isimpossible in this circumstance. Therefore, it is concluded that , like bainite in steels and Ag-Cd, bainite in Cu-Zn-Alalloys nucleates by diffusional mechanism, just implied by the experimental existence of solute-depleted zone.

  18. Principles of rock mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Turchaninov, I.A.; Iofis, M.A.; Kasparyan, E.V.

    1979-01-01

    This book presents the principles of rock mechanics in a systematic way, reflecting both the historic development and the contemporary status of theoretical and experimental techniques used for the determination of the properties and stress state of rock masses, calculation of elements of systems for exploitation of useful mineral deposits and the design of mine openings. The subject of rock mechanics is discussed and methods and basic approaches are analyzed. The most widely used methods for determining the properties of rock in specimens and in situ are described. Problems of determining the stress strain state of the rock around mine openings by both experimental and analytic methods are discussed. The primary results of the study of the stress state of rock around main, development and production openings are presented. Problems of the movement of rock due to extraction of minerals are analyzed in detail, as are the conditions and causes of the development of rock bursts and sudden release of rock and gas in both surface and underground mines. Procedures for preventing or localizing rock bursts or sudden outbursts are described. (313 refs.)

  19. [Inflammasome: activation mechanisms].

    Science.gov (United States)

    Suárez, Raibel; Buelvas, Neudo

    2015-03-01

    Inflammation is a rapid biologic response of the immune system in vascular tissues, directed to eliminate stimuli capable of causing damage and begin the process of repair. The macromolecular complexes known as "inflammasomes" are formed by a receptor, either NOD (NLR) or ALR, the receptor absent in melanoma 2 (AIM2). In addition, the inflammasome is formed by the speck-like protein associated to apoptosis (ASC) and procaspase-1, that may be activated by variations in the ionic and intracellular and extracellular ATP concentrations; and the loss of stabilization of the fagolisosomme by internalization of insoluble crystals and redox mechanisms. As a result, there is activation of the molecular platform and the processing of inflammatory prointerleukins to their active forms. There are two modalities of activation of the inflammasome: canonical and non-canonical, both capable of generating effector responses. Recent data associate NLRP 3, IL-1β and IL-18 in the pathogenesis of a variety of diseases, including atherosclerosis, type II diabetes, hyperhomocysteinemia, gout, malaria and hypertension. The inflammasome cascade is emerging as a new chemotherapeutic target in these diseases. In this review we shall discuss the mechanisms of activation and regulation of the inflammasome that stimulate, modulate and resolve inflammation.

  20. Biochemical mechanisms underlying atherogenesis

    Directory of Open Access Journals (Sweden)

    Dr.P.V.L.N. Srinivasa Rao

    2012-02-01

    Full Text Available Atherosclerosis remains one of the major causes of death and premature disability in developed countries. Though atherosclerosis was formerly considered a bland lipid storage disease, substantial advances in basic and experimental sciences have illuminated the role of endothelium, inflammation and immune mechanisms in its pathogenesis. Current concept of atherosclerosis is that of a dynamic and progressive disease arising from in- jury to endothelium, also known as endothelial dysfunction and an inflammatory response to that injury. The lesions of atherosclerosis occur principally in large and medium sized arteries. Atherosclerosis affects various regions of the circulation preferentially and can lead to ischemia of heart, brain or extremities resulting in in- farction.This produces distinct clinical manifestations depending on the vessel involved. Several predisposing factors to cardiovascular diseases such as diabetes mellitus, hypertension, obesity, infections act as triggers to the devel- opment of atherosclerosis by causing endothelial dysfunction and/or promoting inflammatory response. The evolution of pathogenetic mechanisms has passed through various directions such as oxidative stress, inflam- mation and immune responses. It is now known that all these are not acting independently but are interrelated and getting unified in the current concept of atherogenesis. The following discussion aims at providing an in- sight into these developments which can help in a better comprehension of the disease and management of its clinical complications

  1. 1st National Mechanics Congress

    CERN Document Server

    Nieuwstadt, F

    1990-01-01

    The Department of Applied Mechanics of the Royal Institution of Engineers in the Netherlands (Koninklijk Instituut van Ingenieurs) organised on April 2-4, 1990 the first National Applied Mechanics Congress about the theme: "Integration of Theory and Applications in Applied Mechanics" The idea behind this initiative was to bring together the Applied Mechanics communities in The Netherlands and Belgium and to create an environment in which new developments in the field could be discussed and in which connections to other disciplines could be established. Among an extensive list of possible subjects the following were selected as congress topics: - non-linear material behaviour, - chaos, - mechatronics, - liquid-solid interactions, - mathematics and applied mechanics, - integration of Applied Mechanics and other disciplines. Applied Mechanics comprises both solid mechanics and fluid mechanics. These can be subdivided further into: rheology, plasticity, theory of plates and shells, theory of elasticity, multibody...

  2. Mechanical and geometric advantages in compliant mechanism optimization

    Institute of Scientific and Technical Information of China (English)

    Michael Yu WANG

    2009-01-01

    This paper presents a focused examination of the mechanical and geometric advantages in compliant mechanisms and their ramifications in the design formula-tions of compliant mechanisms posed as a topology optimization problem. With a linear elastic structuralanalysis, we quantify mechanical (and geometric) advan-tage in terms of the stiffness elements of the mechanism's structure. We then analyze the common formulations of compliant mechanism optimization and the role of the external springs added in the formulations. It is shown that the common formulations using mechanical (or geometric) advantage would directly emulate at best a rigid-body linkage to the true optimum design. As a result, the topology optimization generates point flexures in the resulting optimal mechanisms. A case study is investigated to demonstrate the resulting trends in the current formula-tions.

  3. Fresh look at electron-transfer mechanisms via the donor/acceptor bindings in the critical encounter complex.

    Science.gov (United States)

    Rosokha, Sergiy V; Kochi, Jay K

    2008-05-01

    . First, Q or = 1, the overwhelming dominance of the resonance stabilization (H(DA)) predicts the odd-electron mobility between the donor and acceptor to occur without an activation barrier such that bimolecular electron transfer is coincident with their diffusional encounter. In between lies a potentially infinite set of states, 0 now classical Marcus outer-sphere mechanism. Next, the "inner-sphere" mechanism derives from moderate (localized) donor/acceptor bindings and includes the mechanistic concept of the bridged-activated complex introduced by Taube for a wide variety of ligand-based redox dyads. Finally, the "interior" mechanism is also another subclass of the Taube (inner-sphere) classification, and it lies at the other extreme of very fast electron-transfer rate processes (heretofore unrecognized), arising from the spontaneous annihilation of the donor/acceptor dyad to the delocalized (electron-transfer) complex as it descends barrierlessly into the chemical "black hole" that is rate-limited solely by diffusion.

  4. Hydro-mechanical processes

    Energy Technology Data Exchange (ETDEWEB)

    Laouafa, F.; Kazmierczak, J.B. [Institut National de l' Environnement Industriel et des Risques (INERIS), Parc Technologique ALATA, 60 - Verneuil en Halatte (France); Armand, G. [Agence Nationale pour la Gestion des Dechets Radioactifs, Lab. de Souterrain de Meuse/Haute-Marne, 55 - Bure (France); Vaunat, J. [Catalonia UPC- Technical Univ., Barcelona (Spain); Jobmann, M.; Polster, M. [DBETEC- DBE Technology GmbH, Peine (Germany); Su, K.; Lebon, P.; Plas, F.; Armand, G.; Abou-Chakra Guery, A.; Cormery, F.; Shao, J.F.; Kondo, D. [ANDRA - Agence Nationale pour la Gestion des Dechets Radioactifs, 92 - Chatenay Malabry (France); Souley, M. [Institut National de l' Environnement Industriel et des Risques (INERIS), 54 - Nancy (France); Coll, C.; Charlier, R.; Collin, F.; Gerard, P. [Liege Univ., Dept. ArGEnCo (Belgium); Xiang Ling, Li [ESV EURIDICE, SCK.CEN, Belgian Nuclear Research Centre, Mol (Belgium); Collin, F. [Liege Univ., Charge de Recherches FNRS (Belgium); Pellet, F.L.; Fabre, G. [University Joseph Fourier, Laboratory 3S-R, 38 - Grenoble (France); Garcia-Sineriz, J.L.; Rey, M. [AITEMIN - Asociacion para la Investigacion y Desarrollo Industrial de los Recursos Naturales, Madrid (Spain); Mayor, J.C. [ENRESA - Empresa Nacional des Residuos Radioactivos, Madrid (Spain); Castellanos, E.; Romero, E.; Lloret, A.; Gens, A. [Catalunya Univ. Politecnica, UPC (Spain); Villar, M.V. [CIEMAT - Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain); Chambon, R. [Laboratoire 3S, UJF-INPG-CNRS, 38 - Grenoble (France); Czaikowski, O.; Lux, K.H. [Clausthal Univ. of Technology, Professorship for Waste Disposal and Geomechanics, Clausthal-Zellerfeld (Germany); Van Geet, M.; Bastiaens, W.; Volckaert, G.; Weetjens, E.; Sillen, X. [SCK-CEN, Waste and Disposal dept., Mol (Belgium); ONDRAF/NIRAS, Brussel (Belgium); Imbert, Ch. [CEA Saclay, Dept. de Physico-Chimie (DPC/SCCME/LECBA), 91 - Gif sur Yvette (France)] [and others

    2007-07-01

    This session gathers 13 articles dealing with: three-dimensional and time stepping modelling of the whole Meuse/Haute-Marne ANDRA URL (F. Laouafa, J.B. Kazmierczak, G. Armand, J. Vaunat, M. Jobmann, M. Polster); a constitutive model for a deep argillaceous rock using Hoek-Brown criteria (K. Su, C. Chavant, M. Souley); the long term behaviour of the Boom clay: influence of viscosity on the pore pressure distribution (C. Coll, R. Charlier, X.L. Li, F. Collin); the microstructural changes induced by viscoplastic deformations in argillaceous rocks (F.L. Pellet, G. Fabre, K. Su, P. Lebon); the engineered barrier experiment at Mont Terri rock laboratory (J.L. Garcia-Sineriz, M. Rey, J.C. Mayor); the chemical influence on the Hydro-Mechanical behaviour of high-density FEBEX bentonite (E. Castellanos, M.V. Villar, E. Romero, A. Lloret, A. Gens); the influence of water exchanges on the gallery convergence (P. Gerard, R. Charlier, R. Chambon, F. Collin); a new method for ageing resistant storage of argillaceous rock samples to achieve reproducible experimental results even after long intermediate storage times (O. Czaikowski, K.H. Lux); the installation and evaluation of a large-scale in-situ shaft seal experiment in Boom clay the RESEAL project M. Van Geet, W. Bastiaens, G. Volckaert, E. Weetjens, X. Sillen, A. Gens, M.V. Villar, Ch. Imbert, M. Filippi, F. Plas); the hydro-Mechanical response of the Callovo-Oxfordian mud-stone around a deep vertical drift (J. Vaunat, B. Garitte, A. Gens, K. Su, G. Armand); the sensitivity of total stress to changes in externally applied water pressure in KBS-3 buffer bentonite (J.F. Harrington, D.J. Birchall, P. Sellin); the comparison of the poro-elastic behavior of Meuse/Haute Marne and Tournemire argillites: effect of loading and saturation states (E. Bemer, A. Noiret, F. Homand, A. Rejeb); and the multi-scale modelling of the argillites mechanical behaviour (A. Abou-Chakra Guery, F. Cormery, K. Su, J.F. Shao, D. Kondo)

  5. Mechanics of Sheeting Joints

    Science.gov (United States)

    Martel, S. J.

    2015-12-01

    Physical breakdown of rock across a broad scale spectrum involves fracturing. In many areas large fractures develop near the topographic surface, with sheeting joints being among the most impressive. Sheeting joints share many geometric, textural, and kinematic features with other joints (opening-mode fractures) but differ in that they are (a) discernibly curved, (b) open near the topographic surface, and (c) form subparallel to the topographic surface. Where sheeting joints are geologically young, the surface-parallel compressive stresses are typically several MPa or greater. Sheeting joints are best developed beneath domes, ridges, and saddles; they also are reported, albeit rarely, beneath valleys or bowls. A mechanism that accounts for all these associations has been sought for more than a century: neither erosion of overburden nor high lateral compressive stresses alone suffices. Sheeting joints are not accounted for by Mohr-Coulomb shear failure criteria. Principles of linear elastic fracture mechanics, together with the mechanical effect of a curved topographic surface, do provide a basis for understanding sheeting joint growth and the pattern sheeting joints form. Compressive stresses parallel to a singly or doubly convex topographic surface induce a tensile stress perpendicular to the surface at shallow depths; in some cases this alone could overcome the weight of overburden to open sheeting joints. If regional horizontal compressive stresses, augmented by thermal stresses, are an order of magnitude or so greater than a characteristic vertical stress that scales with topographic amplitude, then topographic stress perturbations can cause sheeting joints to open near the top of a ridge. This topographic effect can be augmented by pressure within sheeting joints arising from water, ice, or salt. Water pressure could be particularly important in helping drive sheeting joints downslope beneath valleys. Once sheeting joints have formed, the rock sheets between

  6. Principles of discrete time mechanics

    CERN Document Server

    Jaroszkiewicz, George

    2014-01-01

    Could time be discrete on some unimaginably small scale? Exploring the idea in depth, this unique introduction to discrete time mechanics systematically builds the theory up from scratch, beginning with the historical, physical and mathematical background to the chronon hypothesis. Covering classical and quantum discrete time mechanics, this book presents all the tools needed to formulate and develop applications of discrete time mechanics in a number of areas, including spreadsheet mechanics, classical and quantum register mechanics, and classical and quantum mechanics and field theories. A consistent emphasis on contextuality and the observer-system relationship is maintained throughout.

  7. Martensitic nucleation mechanism

    Institute of Scientific and Technical Information of China (English)

    陈奇志; 桑灿; 吴杏芳; 柯俊

    1997-01-01

    A sort of special dislocation configuration was deformation-induced in an Fe-Ni-V-C alloy by in-situ elongation tests of TEM. The cooling in-situ observations, as well as the SADPs from the region of the special dislocation configurations, proved that they are martensitic nuclei. In martensitic transformation, a nucleus changed into a small martensitic sub-plate, and a group of parallel sub-plates that formed from a group of parallel nuclei made up a big martensitic plate Martensitic transformation involved opposite shear between adjacent martensitic nuclei. By using the reduced-cell method, the crystallographic structure of observed martensitic nuclei was indexed as a face-centered orthogonal (FCO) lattice, which was explained by the nucleation mechanism proposed by the present authors. The crystallographic analysis confirmed that the defect faulting involved in martensitic nucleation took place among three close pakked planes, instead of between two adjacent planes as an ordinary stacking fault.

  8. Quantum mechanics with applications

    CERN Document Server

    Beard, David B

    2014-01-01

    This introductory text emphasizes Feynman's development of path integrals and its application to wave theory for particles. Suitable for undergraduate and graduate students of physics, the well-written, clear, and rigorous text was written by two of the nation's leading authorities on quantum physics. A solid foundation in quantum mechanics and atomic physics is assumed. Early chapters provide background in the mathematical treatment and particular properties of ordinary wave motion that also apply to particle motion. The close relation of quantum theory to physical optics is stressed. Subsequent sections emphasize the physical consequences of a wave theory of material properties, and they offer extensive applications in atomic physics, nuclear physics, solid state physics, and diatomic molecules. Four helpful Appendixes supplement the text.

  9. Molecular Mechanisms of Parturition

    Directory of Open Access Journals (Sweden)

    F. Ferré

    1997-01-01

    Full Text Available The initial signal for triggering human parturition might be fetal but of trophoblastic origin. Concomitantly, this placental signal would have as its target not only the uterus but also the fetus by activating its hypothalamo-pituitary-adrenocortical axis. The latter would represent a second fetal signal which, at the fetomaternal interface, would amplify and define in time the mechanisms responsible for the onset of labor, implying changes in the myometrial and cervical extracellular matrix associated with the accession of the contractile phenotype for myometrial cells. At each phase of these processes in the utero-feto-placental system, the nature of these signals remains to be identified. Is there a single substance, or rather, and more likely, a combination of several?

  10. Submunition Dispensing Mechanisms .

    Directory of Open Access Journals (Sweden)

    S.L. Kholi

    1997-10-01

    Full Text Available The effectiveness of a weapon system is enhanced manifold when it is incorporated with submunitions instead of being a unitary one. A large unitary warhead produces effects that are too concentrated and localised for many target types, resulting in a very high probability of either causing no damage or an over-kill. The submunition warhead incorporating a single-stage ejection process has the drawbacks of lesser area coverage and non-uniform distribution of submunitions. To overcome the above drawbacks, dispensing mechanisms with multistage ejection of submunitions are being employed worldwide by the warhead designers. Extensive work has been carried out by the authors to achieve wide area coverage by using multistage ejection instead of single-stage ejection.

  11. Mechanics of moving materials

    CERN Document Server

    Banichuk, Nikolay; Neittaanmäki, Pekka; Saksa, Tytti; Tuovinen, Tero

    2014-01-01

    This book deals with theoretical aspects of modelling the mechanical behaviour of manufacturing, processing, transportation or other systems in which the processed or supporting material is travelling through the system. Examples of such applications include paper making, transmission cables, band saws, printing presses, manufacturing of plastic films and sheets, and extrusion of aluminium foil, textiles and other materials.   The work focuses on out-of-plane dynamics and stability analysis for isotropic and orthotropic travelling elastic and viscoelastic materials, with and without fluid-structure interaction, using analytical and semi-analytical approaches.  Also topics such as fracturing and fatigue are discussed in the context of moving materials. The last part of the book deals with optimization problems involving physical constraints arising from the stability and fatigue analyses, including uncertainties in the parameters.   The book is intended for researchers and specialists in the field, providin...

  12. New Modal Quantum Mechanics

    CERN Document Server

    Hollowood, Timothy J

    2013-01-01

    We describe an interpretation of quantum mechanics based on reduced density matrices of sub-systems from which the standard Copenhagen interpretation emerges as an effective description for macro-systems. The interpretation is a modal one, but does not suffer from the range of problems that plague other modal interpretations. The key feature is that quantum states carry an additional property assignment in the form of one the eigenvectors of the reduced density matrix which evolves evolves according to a stochastic process driven by the unmodified Schrodinger equation, but it is usually hidden from the emergent classical description due to the ergodic nature of its dynamics. However, during a quantum measurement, ergodicity is broken by decoherence and definite outcomes occur with probabilities that agree with the Born rule.

  13. Mechanisms of postoperative pain

    Institute of Scientific and Technical Information of China (English)

    YUE Yun

    2007-01-01

    @@ The practice of modern anaesthesiology has extended into perioperative medicine. Due to their expertise in analgesic drug pharmacology and peripheral nerve blocking, anaesthesiologists have pioneered in the management of acute postoperative pain. Effective postoperative analgesia reduces the incidence of postoperative chronic pain, improves the functioning of organs following surgery and shortens the hospital stay.1,2 Although a variety of analgesic techniques and preventative approaches are at the disposal of modem aneasthesiologists, including patient controlled epidural analgesia (PCEA), patient controlled intravenous analgesia, multimodal analgesia and pre-empty analgesia.Despite this array of strategies, these predominantly opioid based techniques are still limited by side-effects such as vomiting, nausea, itching and urinary retention.To optimize further the management of acute postoperative pain, basic mechanisms of postoperative pain must be explored and new treatments must continue to be developed.

  14. Quo Vadis Quantum Mechanics?

    CERN Document Server

    Dolev, S; Kolenda, N

    2005-01-01

    For more than a century, quantum mechanics has served as a very powerful theory that has expanded physics and technology far beyond their classical limits, yet it has also produced some of the most difficult paradoxes known to the human mind. This book represents the combined efforts of sixteen of today's most eminent theoretical physicists to lay out future directions for quantum physics. The authors include Yakir Aharonov, Anton Zeilinger; the Nobel laureates Anthony Leggett and Geradus 't Hooft; Basil Hiley, Lee Smolin and Henry Stapp. Following a foreword by Roger Penrose, the individual chapters address questions such as quantum non-locality, the measurement problem, quantum insights into relativity, cosmology and thermodynamics, and the possible bearing of quantum phenomena on biology and consciousness.

  15. Mechanisms of Phosphine Toxicity

    Directory of Open Access Journals (Sweden)

    Nisa S. Nath

    2011-01-01

    Full Text Available Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH3, the chemistry of phosphorus is central to its toxicity. The elements above and below phosphorus in the periodic table are nitrogen (N and arsenic (As, which also produce toxic hydrides, namely, NH3 and AsH3. The three hydrides cause related symptoms and similar changes to cellular and organismal physiology, including disruption of the sympathetic nervous system, suppressed energy metabolism and toxic changes to the redox state of the cell. We propose that these three effects are interdependent contributors to phosphine toxicity.

  16. Glaucoma Genes and Mechanisms.

    Science.gov (United States)

    Wiggs, Janey L

    2015-01-01

    Genetic studies have yielded important genes contributing to both early-onset and adult-onset forms of glaucoma. The proteins encoded by the current collection of glaucoma genes participate in a broad range of cellular processes and biological systems. Approximately half the glaucoma-related genes function in the extracellular matrix, however proteins involved in cytokine signaling, lipid metabolism, membrane biology, regulation of cell division, autophagy, and ocular development also contribute to the disease pathogenesis. While the function of these proteins in health and disease are not completely understood, recent studies are providing insight into underlying disease mechanisms, a critical step toward the development of gene-based therapies. In this review, genes known to cause early-onset glaucoma or contribute to adult-onset glaucoma are organized according to the cell processes or biological systems that are impacted by the function of the disease-related protein product.

  17. Mechanisms of neuregulin action.

    Science.gov (United States)

    Talmage, David A

    2008-01-01

    Neuregulin 1 (Nrg1) and ErbB receptor tyrosine kinase signalling is essential for the formation and proper functioning of multiple organ systems and inappropriate Nrgl/ErbB signalling severely compromises health, contributing to such diverse pathologies as cancer and neuropsychiatric disorders. Numerous genetic modelling studies in mice demonstrate that Nrg1 signalling is important in the development of normal neuronal connectivity. Recent studies have identified novel signalling mechanisms and revealed unexpected roles of Nrg1 isoforms in both the developing and adult nervous system. Of particular interest to this discussion are findings linking deficits in Nrg1-ErbB4 signalling to perturbations of synaptic transmission, myelination, and the survival of particular sets of neurons and glia.

  18. The mechanism of translation

    Science.gov (United States)

    Frank, Joachim

    2017-01-01

    Translation of the genetic code on the ribosome into protein is a process of extraordinary complexity, and understanding its mechanism has remained one of the major challenges even though x-ray structures have been available since 2000. In the past two decades, single-particle cryo-electron microscopy has contributed a major share of information on structure, binding modes, and conformational changes of the ribosome during its work cycle, but the contributions of this technique in the translation field have recently skyrocketed after the introduction of a new recording medium capable of detecting individual electrons. As many examples in the recent literature over the past three years show, the impact of this development on the advancement of knowledge in this field has been transformative and promises to be lasting.

  19. Mechanical origin of aftershocks.

    Science.gov (United States)

    Lippiello, E; Giacco, F; Marzocchi, W; Godano, C; de Arcangelis, L

    2015-10-26

    Aftershocks are the most striking evidence of earthquake interactions and the physical mechanisms at the origin of their occurrence are still intensively debated. Novel insights stem from recent results on the influence of the faulting style on the aftershock organisation in magnitude and time. Our study shows that the size of the aftershock zone depends on the fault geometry. We find that positive correlations among parameters controlling aftershock occurrence in time, energy and space are a stable feature of seismicity independently of magnitude range and geographic areas. We explain the ensemble of experimental findings by means of a description of the Earth Crust as an heterogeneous elastic medium coupled with a Maxwell viscoelastic asthenosphere. Our results show that heterogeneous stress distribution in an elastic layer combined with a coupling to a viscous flow are sufficient ingredients to describe the physics of aftershock triggering.

  20. Respiratory fluid mechanics.

    Science.gov (United States)

    Grotberg, James B

    2011-02-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from "capillary-elastic instabilities," as well as nonlinear stabilization from oscillatory core flow which we call the "oscillating butter knife;" liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg-Borgas-Gaver shock.

  1. Mechanisms of phosphine toxicity.

    Science.gov (United States)

    Nath, Nisa S; Bhattacharya, Ishita; Tuck, Andrew G; Schlipalius, David I; Ebert, Paul R

    2011-01-01

    Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH(3)), the chemistry of phosphorus is central to its toxicity. The elements above and below phosphorus in the periodic table are nitrogen (N) and arsenic (As), which also produce toxic hydrides, namely, NH(3) and AsH(3). The three hydrides cause related symptoms and similar changes to cellular and organismal physiology, including disruption of the sympathetic nervous system, suppressed energy metabolism and toxic changes to the redox state of the cell. We propose that these three effects are interdependent contributors to phosphine toxicity.

  2. Mechanisms of Phosphine Toxicity

    Science.gov (United States)

    Nath, Nisa S.; Bhattacharya, Ishita; Tuck, Andrew G.; Schlipalius, David I.; Ebert, Paul R.

    2011-01-01

    Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH3), the chemistry of phosphorus is central to its toxicity. The elements above and below phosphorus in the periodic table are nitrogen (N) and arsenic (As), which also produce toxic hydrides, namely, NH3 and AsH3. The three hydrides cause related symptoms and similar changes to cellular and organismal physiology, including disruption of the sympathetic nervous system, suppressed energy metabolism and toxic changes to the redox state of the cell. We propose that these three effects are interdependent contributors to phosphine toxicity. PMID:21776261

  3. [Conditioning mechanisms and psychoneuroimmunology].

    Science.gov (United States)

    Stockhorst, Ursula; Klosterhalfen, Sibylle

    2005-01-01

    This chapter deals with the role of conditioning principles in psychoneuroimmunology (PNI). We will first describe the paradigms of classical and instrumental conditioning and classify immune parameters that are subject to conditioning (chapter 1). So far, PNI research mainly uses classical (or Pavlovian) conditioning. We will summarize some of the paradigmatic studies, mainly animal studies (chapter 2) and also describe studies that support the clinical relevance of classical conditioning, i. e., in the pharmacological treatment of autoimmune diseases, transplantation and tumor chemotherapy (chapter 3). A study of our group on anticipatory immunomodulation in pediatric cancer patients is reported. Mechanisms mediating conditioned immunomodulation are summarized (chapter 4). We also describe studies that analyze the impact of instrumental conditioning contingencies on immune functioning (chapter 5). Finally, research perspectives are summarized (chapter 6).

  4. Teaching Continuum Mechanics in a Mechanical Engineering Program

    Science.gov (United States)

    Liu, Yucheng

    2011-01-01

    This paper introduces a graduate course, continuum mechanics, which is designed for and taught to graduate students in a Mechanical Engineering (ME) program. The significance of continuum mechanics in engineering education is demonstrated and the course structure is described. Methods used in teaching this course such as topics, class…

  5. PT quantum mechanics.

    Science.gov (United States)

    Bender, Carl M; DeKieviet, Maarten; Klevansky, S P

    2013-04-28

    PT-symmetric quantum mechanics (PTQM) has become a hot area of research and investigation. Since its beginnings in 1998, there have been over 1000 published papers and more than 15 international conferences entirely devoted to this research topic. Originally, PTQM was studied at a highly mathematical level and the techniques of complex variables, asymptotics, differential equations and perturbation theory were used to understand the subtleties associated with the analytic continuation of eigenvalue problems. However, as experiments on PT-symmetric physical systems have been performed, a simple and beautiful physical picture has emerged, and a PT-symmetric system can be understood as one that has a balanced loss and gain. Furthermore, the PT phase transition can now be understood intuitively without resorting to sophisticated mathematics. Research on PTQM is following two different paths: at a fundamental level, physicists are attempting to understand the underlying mathematical structure of these theories with the long-range objective of applying the techniques of PTQM to understanding some of the outstanding problems in physics today, such as the nature of the Higgs particle, the properties of dark matter, the matter-antimatter asymmetry in the universe, neutrino oscillations and the cosmological constant; at an applied level, new kinds of PT-synthetic materials are being developed, and the PT phase transition is being observed in many physical contexts, such as lasers, optical wave guides, microwave cavities, superconducting wires and electronic circuits. The purpose of this Theme Issue is to acquaint the reader with the latest developments in PTQM. The articles in this volume are written in the style of mini-reviews and address diverse areas of the emerging and exciting new area of PT-symmetric quantum mechanics.

  6. High mechanical advantage design of six-bar Stephenson mechanism for servo mechanical presses

    Directory of Open Access Journals (Sweden)

    Jianguo Hu

    2016-06-01

    Full Text Available This article proposed a two-phase design scheme of Stephenson six-bar working mechanisms for servo mechanical presses with high mechanical advantage. In the qualitative design phase, first, a Stephenson six-bar mechanism with a slide was derived from Stephenson six-bar kinematic chains. Second, based on the instant center analysis method, the relationship between mechanical advantage and some special instant centers was founded, and accordingly a primary mechanism configuration with high mechanical advantage was designed qualitatively. Then, a parameterized prototype model was established, and the influences of design parameters toward slide kinematical characteristics were analyzed. In the quantitative design phase, a multi-objective optimization model, aiming at high mechanical advantage and dwelling characteristics, was built, and a case design was done to find optimal dimensions. Finally, simulations based on the software ADAMS were conducted to compare the transmission characteristics of the optimized working mechanism with that of slide-crank mechanism and symmetrical toggle mechanism, and an experimental press was made to validate the design scheme. The simulation and experiment results show that, compared with general working mechanisms, the Stephenson six-bar working mechanism has higher mechanical advantage and better dwelling characteristics, reducing capacities and costs of servo motors effectively.

  7. Mechanical Property of Foamed Metal

    Institute of Scientific and Technical Information of China (English)

    LIU Pei-sheng; SANG Hai-bo

    2004-01-01

    A comprehensive study on the mechanical behavior of foamed metals was demonstrated. The relationship among their mechanical properties, preparation method, porosity and the structure was briefly studied as well.

  8. TREND MECHANISMS IN CONTEMPORARY FASHION

    DEFF Research Database (Denmark)

    Mackinney-Valentin, Maria

    2013-01-01

    Explores a spatial approach to trend mechanisms that is argued to be more contemporary than the traditional temporal appraoch.......Explores a spatial approach to trend mechanisms that is argued to be more contemporary than the traditional temporal appraoch....

  9. Statistical mechanics of nonequilibrium liquids

    CERN Document Server

    Evans, Denis J; Craig, D P; McWeeny, R

    1990-01-01

    Statistical Mechanics of Nonequilibrium Liquids deals with theoretical rheology. The book discusses nonlinear response of systems and outlines the statistical mechanical theory. In discussing the framework of nonequilibrium statistical mechanics, the book explains the derivation of a nonequilibrium analogue of the Gibbsian basis for equilibrium statistical mechanics. The book reviews the linear irreversible thermodynamics, the Liouville equation, and the Irving-Kirkwood procedure. The text then explains the Green-Kubo relations used in linear transport coefficients, the linear response theory,

  10. MECHANISM TO DRAW MACLAURIN TRISECTRIX

    Directory of Open Access Journals (Sweden)

    Mirela CHERCIU

    2013-05-01

    Full Text Available It is used a geometrical method for generating Maclaurin trisectrix and based on it , thesynthesis of a mechanism that can draw it, is made. The structure of the found mechanism is R-RTRTtype, having two driving elements with correlated movements. This mechanism is analysedand the desired curve is obtained just for certain dimensions of the mechanism. The mechanism’smovement is studied based on some diagrams and different outputs are obtained for certain initialdimensions of the mechanism’s.

  11. Mechanisms of Herbicide-resistance

    Institute of Scientific and Technical Information of China (English)

    MA Hong; CHEN Yibing; TAO Bo

    2006-01-01

    This paper discussed mechanisms of herbicide-resistance. There are at least four mechanisms identified by which weeds become resistant to a herbicide. The two most common mechanisms are those involving metabolic reactions and changes in the deoxyribonucleic acid sequence (mutations) that alter the structure and features of the target proteins. The other two mechanisms involve either an alteration in the penetration or translocation of the herbicides to the target site or the depolarization of membrane within the weed.

  12. Von Bekesy and cochlear mechanics

    NARCIS (Netherlands)

    Olson, Elizabeth S.; Duifhuis, Hendrikus; Steele, Charles R.

    2012-01-01

    Georg Bekesy laid the foundation for cochlear mechanics, foremost by demonstrating the traveling wave that is the substrate for mammalian cochlear mechanical processing. He made mechanical measurements and physical models in order to understand that fundamental cochlear response. In this tribute to

  13. Mechanisms and Reduction in Psychiatry

    DEFF Research Database (Denmark)

    Andersen, Lise Marie

    2016-01-01

    The view that psychiatry should be elucidating the mechanisms behind mental phenomena is gaining momentum. This view, coupled with an intuition that such mechanisms must, by nature, be biological, has inspired the field to look to cognitive neuroscience for classification of mental illnesses. One...... of causation and mechanism to bridge the gab between mechanistic explanations and multilevel models of mental disorders....

  14. Gradient systems and mechanical systems

    Institute of Scientific and Technical Information of China (English)

    Fengxiang Mei; Huibin Wu

    2016-01-01

    All types of gradient systems and their properties are discussed. Two problems connected with gradient sys-tems and mechanical systems are studied. One is the direct problem of transforming a mechanical system into a gradi-ent system, and the other is the inverse problem, which is transforming a gradient system into a mechanical system.

  15. Mechanisms of antidepressant resistance

    Directory of Open Access Journals (Sweden)

    Wissam eEl Hage

    2013-11-01

    Full Text Available Depression is one of the most frequent and severe mental disorder. Since the discovery of antidepressant properties of the imipramine and then after of other tricyclic compounds, several classes of psychotropic drugs have shown be effective in treating major depressive disorder. However, there is a wide range of variability in response to antidepressants that might lead to non response or partial response or in increased rate of relapse or recurrence. The mechanisms of response to antidepressant therapy are poorly understood, and few biomarkers are available than can predict response to pharmacotherapy. Here, we will first review markers that can be used to predict response to pharmacotherapy, such as markers of drug metabolism or blood-brain barrier function, the activity of specific brain areas or neurotransmitter systems, hormonal dysregulations or plasticity, and related molecular targets. We will describe both clinical and preclinical studies and describe factors that might affect the expression of these markers, including environmental or genetic factors and comorbidities. This information will permit us to suggest practical recommendations and innovative treatment strategies to improve therapeutic outcomes.

  16. Epigenetic mechanisms in epilepsy.

    Science.gov (United States)

    Kobow, Katja; Blümcke, Ingmar

    2014-01-01

    In humans, genomic DNA is organized in 23 chromosome pairs coding for roughly 25,000 genes. Not all of them are active at all times. During development, a broad range of different cell types needs to be generated in a highly ordered and reproducible manner, requiring selective gene expression programs. Epigenetics can be regarded as the information management system that is able to index or bookmark distinct regions in our genome to regulate the readout of DNA. It further comprises the molecular memory of any given cell, allowing it to store information of previously experienced external (e.g., environmental) or internal (e.g., developmental) stimuli, to learn from this experience and to respond. The underlying epigenetic mechanisms can be synergistic, antagonistic, or mutually exclusive and their large variety combined with the variability and interdependence is thought to provide the molecular basis for any phenotypic variation in physiological and pathological conditions. Thus, widespread reconfiguration of the epigenome is not only a key feature of neurodevelopment, brain maturation, and adult brain function but also disease.

  17. Respiratory Fluid Mechanics

    Science.gov (United States)

    Grotberg, James

    2005-11-01

    This brief overview of our groups activities includes liquid plug propagation in single and bifurcating tubes, a subject which pertains to surfactant delivery, liquid ventilation, pulmonary edema, and drowning. As the plug propagates, a variety of flow patterns may emerge depending on the parameters. It splits unevenly at airway bifurcations and can rupture, which reopens the airway to gas flow. Both propagation and rupture may damage the underlying airway wall cells. Another topic is surfactant dynamics and flow in a model of an oscillating alveolus. The analysis shows a nontrivial cycle-averaged surfactant concentration gradient along the interface that generates steady streaming. The steady streaming patterns particularly depend on the ratio of inspiration to expiration time periods and the sorption parameter. Vortices, single and multiple, may be achieved, as well as a saddle point configuration. Potential applications are pulmonary drug administration, cell-cell signaling pathways, and gene therapy. Finally, capillary instabilities which cause airway closure, and strategies for stabilization, will be presented. This involves the core-annular flow of a liquid-lined tube, where the core (air) is forced to oscillate axially. The stabilization mechanism is similar to that of a reversing butter knife, where the core shear wipes the growing liquid bulge, from the Rayleigh instability, back on to the tube wall during the main tidal volume stroke, but allows it to grow back as the stroke and shear turn around.

  18. Statistical Mechanics of Zooplankton.

    Science.gov (United States)

    Hinow, Peter; Nihongi, Ai; Strickler, J Rudi

    2015-01-01

    Statistical mechanics provides the link between microscopic properties of many-particle systems and macroscopic properties such as pressure and temperature. Observations of similar "microscopic" quantities exist for the motion of zooplankton, as well as many species of other social animals. Herein, we propose to take average squared velocities as the definition of the "ecological temperature" of a population under different conditions on nutrients, light, oxygen and others. We test the usefulness of this definition on observations of the crustacean zooplankton Daphnia pulicaria. In one set of experiments, D. pulicaria is infested with the pathogen Vibrio cholerae, the causative agent of cholera. We find that infested D. pulicaria under light exposure have a significantly greater ecological temperature, which puts them at a greater risk of detection by visual predators. In a second set of experiments, we observe D. pulicaria in cold and warm water, and in darkness and under light exposure. Overall, our ecological temperature is a good discriminator of the crustacean's swimming behavior.

  19. Mechanics of universal horizons

    CERN Document Server

    Berglund, Per; Mattingly, David

    2012-01-01

    Modified gravity models such as Ho\\v{r}ava-Lifshitz gravity or Einstein-{\\ae}ther theory violate local Lorentz invariance and therefore destroy the notion of a universal light cone. Despite this, in the infrared limit both models above possess static, spherically symmetric solutions with "universal horizons" - hypersurfaces that are causal boundaries between an interior region and asymptotic spatial infinity. In other words, there still exist black hole solutions. We construct a Smarr formula (the relationship between the total energy of the spacetime and the area of the horizon) for such a horizon in Einstein-{\\ae}ther theory. We further show that a slightly modified first law of black hole mechanics still holds with the relevant area now a cross-section of the universal horizon. We construct new analytic solutions for certain Einstein-{\\ae}ther Lagrangians and illustrate how our results work in these exact cases. Our results suggest that holography may be extended to these theories despite the very differen...

  20. Topics in statistical mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Elser, V.

    1984-05-01

    This thesis deals with four independent topics in statistical mechanics: (1) the dimer problem is solved exactly for a hexagonal lattice with general boundary using a known generating function from the theory of partitions. It is shown that the leading term in the entropy depends on the shape of the boundary; (2) continuum models of percolation and self-avoiding walks are introduced with the property that their series expansions are sums over linear graphs with intrinsic combinatorial weights and explicit dimension dependence; (3) a constrained SOS model is used to describe the edge of a simple cubic crystal. Low and high temperature results are derived as well as the detailed behavior near the crystal facet; (4) the microscopic model of the lambda-transition involving atomic permutation cycles is reexamined. In particular, a new derivation of the two-component field theory model of the critical behavior is presented. Results for a lattice model originally proposed by Kikuchi are extended with a high temperature series expansion and Monte Carlo simulation. 30 references.

  1. Warp Field Mechanics 101

    Science.gov (United States)

    White, Harold

    2011-01-01

    This paper will begin with a short review of the Alcubierre warp drive metric and describes how the phenomenon might work based on the original paper. The canonical form of the metric was developed and published in [6] which provided key insight into the field potential and boost for the field which remedied a critical paradox in the original Alcubierre concept of operations. A modified concept of operations based on the canonical form of the metric that remedies the paradox is presented and discussed. The idea of a warp drive in higher dimensional space-time (manifold) will then be briefly considered by comparing the null-like geodesics of the Alcubierre metric to the Chung-Freese metric to illustrate the mathematical role of hyperspace coordinates. The net effect of using a warp drive technology coupled with conventional propulsion systems on an exploration mission will be discussed using the nomenclature of early mission planning. Finally, an overview of the warp field interferometer test bed being implemented in the Advanced Propulsion Physics Laboratory: Eagleworks (APPL:E) at the Johnson Space Center will be detailed. While warp field mechanics has not had a Chicago Pile moment, the tools necessary to detect a modest instance of the phenomenon are near at hand.

  2. Statistical Mechanics of Money

    Science.gov (United States)

    Dragulescu, Adrian; Yakovenko, Victor

    2000-03-01

    We study a network of agents exchanging money between themselves. We find that the stationary probability distribution of money M is the Gibbs distribution exp(-M/T), where T is an effective ``temperature'' equal to the average amount of money per agent. This is in agreement with the general laws of statistical mechanics, because money is conserved during each transaction and the number of agents is held constant. We have verified the emergence of the Gibbs distribution in computer simulations of various trading rules and models. When the time-reversal symmetry of the trading rules is explicitly broken, deviations from the Gibbs distribution may occur, as follows from the Boltzmann-equation approach to the problem. Money distribution characterizes the purchasing power of a system. A seller would maximize his/her income by setting the price of a product equal to the temperature T of the system. Buying products from a system of temperature T1 and selling it to a system of temperature T2 would generate profit T_2-T_1>0, as in a thermal machine.

  3. Mechanisms of antidepressant resistance

    Science.gov (United States)

    El-Hage, Wissam; Leman, Samuel; Camus, Vincent; Belzung, Catherine

    2013-01-01

    Depression is one of the most frequent and severe mental disorder. Since the discovery of antidepressant (AD) properties of the imipramine and then after of other tricyclic compounds, several classes of psychotropic drugs have shown be effective in treating major depressive disorder (MDD). However, there is a wide range of variability in response to ADs that might lead to non response or partial response or in increased rate of relapse or recurrence. The mechanisms of response to AD therapy are poorly understood, and few biomarkers are available than can predict response to pharmacotherapy. Here, we will first review markers that can be used to predict response to pharmacotherapy, such as markers of drug metabolism or blood-brain barrier (BBB) function, the activity of specific brain areas or neurotransmitter systems, hormonal dysregulations or plasticity, and related molecular targets. We will describe both clinical and preclinical studies and describe factors that might affect the expression of these markers, including environmental or genetic factors and comorbidities. This information will permit us to suggest practical recommendations and innovative treatment strategies to improve therapeutic outcomes. PMID:24319431

  4. Genetic mechanisms of parenting.

    Science.gov (United States)

    Mileva-Seitz, Viara R; Bakermans-Kranenburg, Marian J; van IJzendoorn, Marinus H

    2016-01-01

    This article is part of a Special Issue "Parental Care". The complexities of parenting behavior in humans have been studied for decades. Only recently did we begin to probe the genetic and epigenetic mechanisms underlying these complexities. Much of the research in this field continues to be informed by animal studies, where genetic manipulations and invasive tools allow to peek into and directly observe the brain during the expression of maternal behavior. In humans, studies of adult twins who are parents can suggest dimensions of parenting that might be more amenable to a genetic influence. Candidate gene studies can test specific genes in association with parental behavior based on prior knowledge of those genes' function. Gene-by-environment interactions of a specific kind indicating differential susceptibility to the environment might explain why some parents are more resilient and others are more vulnerable to stressful life events. Epigenetic studies can provide the bridge often necessary to explain why some individuals behave differently from others despite common genetic influences. There is a much-needed expansion in parenting research to include not only mothers as the focus-as has been the case almost exclusively to date-but also fathers, grandparents, and other caregivers.

  5. Mechanisms of RNA catalysis.

    Science.gov (United States)

    Lilley, David M J

    2011-10-27

    Ribozymes are RNA molecules that act as chemical catalysts. In contemporary cells, most known ribozymes carry out phosphoryl transfer reactions. The nucleolytic ribozymes comprise a class of five structurally-distinct species that bring about site-specific cleavage by nucleophilic attack of the 2'-O on the adjacent 3'-P to form a cyclic 2',3'-phosphate. In general, they will also catalyse the reverse reaction. As a class, all these ribozymes appear to use general acid-base catalysis to accelerate these reactions by about a million-fold. In the Varkud satellite ribozyme, we have shown that the cleavage reaction is catalysed by guanine and adenine nucleobases acting as general base and acid, respectively. The hairpin ribozyme most probably uses a closely similar mechanism. Guanine nucleobases appear to be a common choice of general base, but the general acid is more variable. By contrast, the larger ribozymes such as the self-splicing introns and RNase P act as metalloenzymes.

  6. Quantum mechanics of leptogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Mendizabal Cofre, Sebastian

    2010-08-15

    Leptogenesis is an attractive mechanism that simultaneously explains the matterantimatter asymmetry of the universe as well as the small masses of the standard model neutrinos. This is performed by naturally extending the standard model with the insertion of right handed neutrinos. Leptogenesis is usually studied via the semi-classical Boltzmann equations. However, these equations suffer from basic conceptual problems and they lack to include many quantum phenomena, such as memory effects and coherence oscillations. In order to fully describe leptogenesis, a full quantum treatment is required. In this work we show how to address leptogenesis systematically in a purely quantum way. We start by studying scalar and fermionic excitations in a plasma by solving the Kadanoff-Baym equations of motion for Green's functions, with significant emphasis on the initial and boundary conditions of the solutions. We compute analytically the asymmetry generated from the departure of equilibrium of a particle in a thermal bath. The comparison with the semi-classical Boltzmann approach is also analysed, leading to a qualitative difference between both methods. The non-locality of the Kadanoff-Baym equations shows how off-shell effects can have a huge impact on the generated asymmetry, effects that cannot be studied with the Boltzmann equations. The insertion of standard model interactions like the decay widths for the particles of the bath is also discussed. We explain how with a trivial insertion of these widths we regain locality on the processes, i.e. we regain the Boltzmann equations. (orig.)

  7. Epigenetic mechanisms in leukemia.

    Science.gov (United States)

    Zaidi, Sayyed K; Trombly, Daniel J; Dowdy, Christopher R; Lian, Jane B; Stein, Janet L; van Wijnen, Andre J; Stein, Gary S

    2012-09-01

    Focal organization of regulatory machinery within the interphase nucleus is linked to biological responsiveness and perturbed in cancer. Lineage determinant Runx proteins organize and assemble multi-protein complexes at sites of transcription within the nucleus and regulate both RNA polymerase II- and I-mediated gene expression. In addition, Runx proteins epigenetically control lineage determining transcriptional programs including: 1) architectural organization of macromolecular complexes in interphase, 2) regulation of gene expression through bookmarking during mitosis, and 3) microRNA-mediated translational control in the interphase nucleus. These mechanisms are compromised with the onset and progression of cancer. For example, the oncogenic AML1-ETO protein, which results from a chromosomal translocation between chromosomes 8 and 21, is expressed in nearly 25% of all acute myelogenous leukemias, disrupts Runx1 subnuclear localization during interphase and compromises transcriptional regulation. Epigenetically, the leukemic protein redirects the Runx1 DNA binding domain to leukemia-specific nuclear microenvironments, modifies regulatory protein accessibility to Runx1 target genes by imprinting repressive chromatin marks, and deregulates the microRNA (miR) profile of diseased myeloid cells. Consequently, the entire Runx1-dependent transcriptional program of myeloid cells is deregulated leading to onset and progression of acute myeloid leukemia and maintenance of leukemic phenotype. We discuss the potential of modified epigenetic landscape of leukemic cells as a viable therapeutic target.

  8. Mechanism of gypsum hydration

    Directory of Open Access Journals (Sweden)

    Pacheco, G.

    1991-06-01

    Full Text Available There is an hypothesis that the mechanism o f gypsum hydration and dehydration is performed through two simultaneous phenomena. In this study we try to clear up this phenomenon using chlorides as accelerators or a mixture of ethanol-methanol as retarders to carry out the gypsum setting. Natural Mexican gypsum samples and a hemihydrate prepared in the laboratory are used. The following analytical techniques are used: MO, DRX, DTA, TG and DTG. In agreement with the obtained results, it can be concluded: that colloid formation depends on the action of accelerators or retarders and the crystals are a consequence of the quantity of hemihydrate formed.

    En el mecanismo de hidratación y deshidratación del yeso existe la hipótesis de que éste se efectúa por dos fenómenos simultáneos. Este estudio intenta esclarecer estos fenómenos, empleando: cloruros como aceleradores o mezcla etanol-metanol como retardadores para efectuar el fraguado del yeso. Se emplean muestras de yeso de origen natural mexicano y hemihydrate preparado en laboratorio; se utilizan técnicas analíticas: MO, DRX, DTA, TG y DTG. De acuerdo a los resultados obtenidos se puede deducir: que la formación del coloide depende de la acción de los agentes aceleradores o retardadores y que los cristales son consecuencia de la cantidad de hemihidrato formado.

  9. Mechanisms of cardiac pain.

    Science.gov (United States)

    Foreman, Robert D; Garrett, Kennon M; Blair, Robert W

    2015-04-01

    Angina pectoris is cardiac pain that typically is manifested as referred pain to the chest and upper left arm. Atypical pain to describe localization of the perception, generally experienced more by women, is referred to the back, neck, and/or jaw. This article summarizes the neurophysiological and pharmacological mechanisms for referred cardiac pain. Spinal cardiac afferent fibers mediate typical anginal pain via pathways from the spinal cord to the thalamus and ultimately cerebral cortex. Spinal neurotransmission involves substance P, glutamate, and transient receptor potential vanilloid-1 (TRPV1) receptors; release of neurokinins such as nuclear factor kappa b (NF-kb) in the spinal cord can modulate neurotransmission. Vagal cardiac afferent fibers likely mediate atypical anginal pain and contribute to cardiac ischemia without accompanying pain via relays through the nucleus of the solitary tract and the C1-C2 spinal segments. The psychological state of an individual can modulate cardiac nociception via pathways involving the amygdala. Descending pathways originating from nucleus raphe magnus and the pons also can modulate cardiac nociception. Sensory input from other visceral organs can mimic cardiac pain due to convergence of this input with cardiac input onto spinothalamic tract neurons. Reduction of converging nociceptive input from the gallbladder and gastrointestinal tract can diminish cardiac pain. Much work remains to be performed to discern the interactions among complex neural pathways that ultimately produce or do not produce the sensations associated with cardiac pain.

  10. On the ENSO Mechanisms

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The El Nino-Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Paci fic Ocean-atmosphere interactions. The oscillatory nature of ENSO requires both positive and negative ocean-atmosphere feedbacks. The positive feedback is dated back to Bjerknes' hypothesis in the 1960s, and different negative feedbacks have been proposed since the 1980s associated with the delayed oscillator, the western Pacific oscillator, the recharge-discharge oscillator, and the advective-reflective oscillator. The de layed oscillator assumes that wave reflection at the western boundary provides a negative feedback for the coupled system to oscillate. The western Pacific oscillator emphasizes equatorial wind in the western Pacific that provides a negative feedback for the coupled system. The recharge-discharge oscillator argues that discharge and recharge of equatorial heat content cause the coupled system to oscillate. The advective-re flective oscillator emphasizes the importance of zonal advection associated with wave reflection at both the western and eastern boundaries. All of these physics are summarized in a unified ENSO oscillator. The de layed oscillator, the western Pacific oscillator, the recharge-discharge oscillator, and the advective-reflec tive oscillator can be extracted as special cases of the unified oscillator. As suggested by this unified oscillator, all of the previous ENSO oscillator mechanisms may be operating in nature.

  11. Statistical Mechanics of Zooplankton.

    Directory of Open Access Journals (Sweden)

    Peter Hinow

    Full Text Available Statistical mechanics provides the link between microscopic properties of many-particle systems and macroscopic properties such as pressure and temperature. Observations of similar "microscopic" quantities exist for the motion of zooplankton, as well as many species of other social animals. Herein, we propose to take average squared velocities as the definition of the "ecological temperature" of a population under different conditions on nutrients, light, oxygen and others. We test the usefulness of this definition on observations of the crustacean zooplankton Daphnia pulicaria. In one set of experiments, D. pulicaria is infested with the pathogen Vibrio cholerae, the causative agent of cholera. We find that infested D. pulicaria under light exposure have a significantly greater ecological temperature, which puts them at a greater risk of detection by visual predators. In a second set of experiments, we observe D. pulicaria in cold and warm water, and in darkness and under light exposure. Overall, our ecological temperature is a good discriminator of the crustacean's swimming behavior.

  12. Mechanical properties of ceramics

    CERN Document Server

    Pelleg, Joshua

    2014-01-01

    This book discusses the mechanical properties of ceramics and aims to provide both a solid background for undergraduate students, as well as serving as a text to bring practicing engineers up to date with the latest developments in this topic so they can use and apply these to their actual engineering work.  Generally, ceramics are made by moistening a mixture of clays, casting it into desired shapes and then firing it to a high temperature, a process known as 'vitrification'. The relatively late development of metallurgy was contingent on the availability of ceramics and the know-how to mold them into the appropriate forms. Because of the characteristics of ceramics, they offer great advantages over metals in specific applications in which hardness, wear resistance and chemical stability at high temperatures are essential. Clearly, modern ceramics manufacturing has come a long way from the early clay-processing fabrication method, and the last two decades have seen the development of sophisticated technique...

  13. Locking mechanism for orthopedic braces

    Science.gov (United States)

    Chao, J. I.; Epps, C. H., Jr.

    1981-01-01

    An orthopedic brace locking mechanism is described which under standing or walking conditions cannot be unlocked, however under sitting conditions the mechanism can be simply unlocked so as to permit bending of the patient's knee. Other features of the device include: (1) the mechanism is rendered operable, and inoperable, dependent upon the relative inclination of the brace with respect to the ground; (2) the mechanism is automatically locked under standing or walking conditions and is manually unlocked under sitting conditions; and (3) the mechanism is light in weight and is relatively small in size.

  14. DYNAMIC MODELING OF METAMORPHIC MECHANISM

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The concept of metamorphic mechanism is put forward according to the change of configurations from one state to another. Different configurations of metamorphic mechanism are described through the method of Huston lower body arrays. Kinematics analyses for metamorphic mechanism with generalized topological structure, including the velocity, angular velocity, acceleration and angular acceleration, are given. Dynamic equations for an arbitrary configuration, including close-loop constraints, are formed by using Kane's equations. For an arbitrary metamorphic mechanism, the transformation matrix of generalized speeds between configuration (*)and(*)+1 is obtained for the first time. Furthermore, configuration-complete dynamic modeling of metamorphic mechanism including all configurations is completely established.

  15. Molecular Electrical Doping of Organic Semiconductors: Fundamental Mechanisms and Emerging Dopant Design Rules.

    Science.gov (United States)

    Salzmann, Ingo; Heimel, Georg; Oehzelt, Martin; Winkler, Stefanie; Koch, Norbert

    2016-03-15

    Today's information society depends on our ability to controllably dope inorganic semiconductors, such as silicon, thereby tuning their electrical properties to application-specific demands. For optoelectronic devices, organic semiconductors, that is, conjugated polymers and molecules, have emerged as superior alternative owing to the ease of tuning their optical gap through chemical variability and their potential for low-cost, large-area processing on flexible substrates. There, the potential of molecular electrical doping for improving the performance of, for example, organic light-emitting devices or organic solar cells has only recently been established. The doping efficiency, however, remains conspicuously low, highlighting the fact that the underlying mechanisms of molecular doping in organic semiconductors are only little understood compared with their inorganic counterparts. Here, we review the broad range of phenomena observed upon molecularly doping organic semiconductors and identify two distinctly different scenarios: the pairwise formation of both organic semiconductor and dopant ions on one hand and the emergence of ground state charge transfer complexes between organic semiconductor and dopant through supramolecular hybridization of their respective frontier molecular orbitals on the other hand. Evidence for the occurrence of these two scenarios is subsequently discussed on the basis of the characteristic and strikingly different signatures of the individual species involved in the respective doping processes in a variety of spectroscopic techniques. The critical importance of a statistical view of doping, rather than a bimolecular picture, is then highlighted by employing numerical simulations, which reveal one of the main differences between inorganic and organic semiconductors to be their respective density of electronic states and the doping induced changes thereof. Engineering the density of states of doped organic semiconductors, the Fermi

  16. Theoretical physics 2 analytical mechanics

    CERN Document Server

    Nolting, Wolfgang

    2016-01-01

    This textbook offers a clear and comprehensive introduction to analytical mechanics, one of the core components of undergraduate physics courses.It follows on naturally from the previous volumes in this series, thus expanding the knowledge in classical mechanics. The book starts with a thorough introduction into Lagrangian mechanics, detailing the d’Alembert principle, Hamilton’s principle and conservation laws. It continues with an in-depth explanation of Hamiltonian mechanics, illustrated by canonical and Legendre transformation, the generalization to quantum mechanics through Poisson brackets and all relevant variational principles. Finally, the Hamilton-Jacobi theory and the transition to wave mechanics are presented in detail. Ideally suited to undergraduate students with some grounding in classical mechanics, the book is enhanced throughout with learning features such as boxed inserts and chapter summaries, with key mathematical derivations highlighted to aid understanding. The text is supported by ...

  17. Statistical earthquake focal mechanism forecasts

    CERN Document Server

    Kagan, Yan Y

    2013-01-01

    Forecasts of the focal mechanisms of future earthquakes are important for seismic hazard estimates and Coulomb stress and other models of earthquake occurrence. Here we report on a high-resolution global forecast of earthquake rate density as a function of location, magnitude, and focal mechanism. In previous publications we reported forecasts of 0.5 degree spatial resolution, covering the latitude range magnitude, and focal mechanism. In previous publications we reported forecasts of 0.5 degree spatial resolution, covering the latitude range from -75 to +75 degrees, based on the Global Central Moment Tensor earthquake catalog. In the new forecasts we've improved the spatial resolution to 0.1 degree and the latitude range from pole to pole. Our focal mechanism estimates require distance-weighted combinations of observed focal mechanisms within 1000 km of each grid point. Simultaneously we calculate an average rotation angle between the forecasted mechanism and all the surrounding mechanisms, using the method ...

  18. The Mechanism of Dishabituation

    Directory of Open Access Journals (Sweden)

    Genevieve Z. Steiner

    2014-02-01

    Full Text Available The dual-process theory of habituation attributes dishabituation, an increase in responding to a habituated stimulus after an interpolated deviant, to sensitisation, a change in arousal. Our previous investigations into elicitation and habituation of the electrodermal Orienting Reflex (OR showed that dishabituation is independent of sensitisation for indifferent stimuli, arguing against dual-process theory’s explanation. However, this could not be tested for significant stimuli in that study, because sensitisation was confounded with incomplete resolution of the preceding OR. This study aimed to clarify the mechanism of dishabituation for significant stimuli by extending the stimulus onset asynchrony (SOA beyond the time required for the phasic response to resolve. Participants completed an auditory dishabituation task with a random SOA of 13-15 s while their electrodermal activity was recorded. The stimulus sequence was 10 standards, 1 deviant, 2-4 standards; counterbalanced innocuous tones. Two counterbalanced conditions were used: silently count all stimuli (significant and no task (indifferent. Skin conductance responses (SCRs and pre-stimulus skin conductance levels (SCLs both decremented over trials 1-10. In both conditions, SCRs showed response recovery and dishabituation, indicating habituation, and post-deviant SCL sensitisation was apparent. Across all trials, phasic ORs were dependent on the pre-stimulus SCL (arousal level; this did not differ with condition. Importantly, dishabituation was independent of sensitisation for both conditions. Findings indicate that sensitisation, the change in state, is a process separate from phasic response resolution, and that arousal consistently predicts OR magnitude, including the dishabituation response. This argues against dual-process theory’s explanation, and instead suggests that dishabituation is a disruption of the habituation process, with magnitude determined by the current arousal

  19. Superspreading mechanisms: An overview

    Science.gov (United States)

    Nikolov, A.; Wasan, D.

    2011-08-01

    An aqueous solution of trisiloxane-ethoxylate surfactants (superspreaders) has fascinating surface properties that promote rapid spreading over hydrophobic substrates and efficiently reduce the surface tension at the air/solution interface to 21-22 mN/m. Superspreaders have a variety of commercial and industrial applications, and can be used as adjuvants, surface modifiers for fabrics, cleaners and much more. Since their discovery in the 1960s, and despite their significant technological applications, the phenomenon that drives superspreading is still not well understood and is under continuous discussion. The goal of the presented review is to discuss and analyze the data presented in the literature and then to elucidate the concepts and mechanisms to explain what drives the fast rate of spreading. Two concepts are presented (and then excluded) for elucidating the understanding of the fast spreading rate over hydrophobic surfaces: the first concept concludes that the spreading is driven by the contact angle dynamics due to the reduction in the surface tension and/or interfacial tension of the solution/substrate leading to a decreased contact angle during spreading and the value of the spreading coefficient S ≥ 0, while the second concept attempts to show that the spreading is driven by the Marangoni flow over a stretching surface of a spreading drop or at the precursor film. However, neither the spreading coefficient, S ≥ 0, nor the Marangoni flow satisfactorily explains why the rate of spreading vs. the degree of surface wettability has a maximum. This review will help readers gain insight on superspreading and stimulate researchers to explore the superspreading phenomenon for novel applications.

  20. Quantum Mechanics/Molecular Mechanics Modeling of Drug Metabolism

    DEFF Research Database (Denmark)

    Lonsdale, Richard; Fort, Rachel M; Rydberg, Patrik;

    2016-01-01

    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......)-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...... 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...

  1. Mechanical ventilation and respiratory mechanics during equine anesthesia.

    Science.gov (United States)

    Moens, Yves

    2013-04-01

    The mechanical ventilation of horses during anesthesia remains a crucial option for optimal anesthetic management, if the possible negative cardiovascular side effects are managed, because this species is prone to hypercapnia and hypoxemia. The combined use of capnography and pitot-based spirometry provide complementary information on ventilation and respiratory mechanics, respectively. This facilitates management of mechanical ventilation in conditions of changing respiratory system compliance (ie, laparoscopy) and when investigating new ventilatory strategies including alveolar recruitment maneuvers and optimization of positive expiratory pressure.

  2. Assessment of mechanical ventilation parameters on respiratory mechanics.

    Science.gov (United States)

    Pidaparti, Ramana M; Koombua, Kittisak; Ward, Kevin R

    2012-01-01

    Better understanding of airway mechanics is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems in intensive-care medicine, as well as pulmonary medicine. Mechanical ventilation depends on several parameters, all of which affect the patient outcome. As there are no systematic numerical investigations of the role of mechanical ventilation parameters on airway mechanics, the objective of this study was to investigate the role of mechanical ventilation parameters on airway mechanics using coupled fluid-solid computational analysis. For the airway geometry of 3 to 5 generations considered, the simulation results showed that airflow velocity increased with increasing airflow rate. Airway pressure increased with increasing airflow rate, tidal volume and positive end-expiratory pressure (PEEP). Airway displacement and airway strains increased with increasing airflow rate, tidal volume and PEEP form mechanical ventilation. Among various waveforms considered, sine waveform provided the highest airflow velocity and airway pressure while descending waveform provided the lowest airway pressure, airway displacement and airway strains. These results combined with optimization suggest that it is possible to obtain a set of mechanical ventilation strategies to avoid lung injuries in patients.

  3. 6th International Conference on Mechanism Science

    CERN Document Server

    Flores, Paulo

    2017-01-01

    This book collects the most recent advances in mechanism science and machine theory with application to engineering. It contains selected peer-reviewed papers of the sixth International Conference on Mechanism Science, held in Nantes, France, 20-23 September 2016, covering topics on mechanism design and synthesis, mechanics of robots, mechanism analysis, parallel manipulators, tensegrity mechanisms, cable mechanisms, control issues in mechanical systems, history of mechanisms, mechanisms for biomechanics and surgery and industrial and nonindustrial applications.

  4. Mechanism of deactivation of triplet-excited riboflavin by ascorbate, carotenoids, and tocopherols in homogeneous and heterogeneous aqueous food model systems.

    Science.gov (United States)

    Cardoso, Daniel R; Olsen, Karsten; Skibsted, Leif H

    2007-07-25

    Tocopherols (alpha, beta, gamma, and delta) and Trolox were found to deactivate triplet-excited riboflavin in homogeneous aqueous solution (7:3 v/v tert-butanol/water) with second-order reaction rates close to diffusion control [k2 between 4.8 x 10(8) (delta-tocopherol) and 6.2 x 10(8) L mol(-1) s(-1) (Trolox) at 24.0 +/- 0.2 degrees C] as determined by laser flash photolysis transient absorption spectroscopy. In aqueous buffer (pH 6.4) the rate constant for Trolox was 2.6 x 10(9) L mol(-1) s1 and comparable to the rate constant found for ascorbate (2.0 x 10(9) L mol(-1) s(-1)). The deactivation rate constant was found to be inferior in heterogeneous systems as shown for alpha-tocopherol and Trolox in aqueous Tween-20 emulsion (approximately by a factor of 4 compared to 7:3 v/v tert-butanol/water). Neither beta-carotene (7:3 v/v tert-butanol/water and Tween-20 emulsion), lycopene (7:3 v/v tert-butanol/water), nor crocin (aqueous buffer at pH 6.4, 7:3 v/v tert-butanol/water, and Tween-20 emulsion) showed any quenching on the triplet excited state of riboflavin. Therefore, all carotenoids seem to reduce the formation of triplet-excited riboflavin through an inner-filter effect. Activation parameters were based on the temperature dependence of the triplet-excited deactivation between 15 and 35 degrees C, and the isokinetic behavior, which was found to include purine derivatives previously studied, confirms a common deactivation mechanism with a bimolecular diffusion-controlled encounter with electron (or hydrogen atom) transfer as rate-determining step. DeltaH for deactivation by ascorbic acid, Trolox, and homologue tocopherols (ranging from 18 kJ mol(-1) for Trolox in Tween-20 emulsion to 184 kJ mol(-1) for ascorbic acid in aqueous buffer at pH 6.4) showed a linear dependence on DeltaS (ranging from -19 J mol(-1) K(-1) for Trolox in aqueous buffer at pH 6.4 to +550 J mol(-1) K(-1) for ascorbic acid in aqueous buffer pH 6.4). Among photooxidation products from the

  5. Activation of B-H, Si-H, and C-F bonds with Tp'Rh(PMe3) complexes: kinetics, mechanism, and selectivity.

    Science.gov (United States)

    Procacci, Barbara; Jiao, Yunzhe; Evans, Meagan E; Jones, William D; Perutz, Robin N; Whitwood, Adrian C

    2015-01-28

    The photochemical reactions of Tp'Rh(PMe3)H2 (1) and thermal reactions of Tp'Rh(PMe3)(CH3)H (1a, Tp' = tris(3,5-dimethylpyrazolyl)borate) with substrates containing B-H, Si-H, C-F, and C-H bonds are reported. Complexes 1 and 1a are known activators of C-H bonds, including those of alkanes. Kinetic studies of reactions with HBpin and PhSiH3 show that photodissociation of H2 from 1 occurs prior to substrate attack, whereas thermal reaction of 1a proceeds by bimolecular reaction with the substrate. Complete intramolecular selectivity for B-H over C-H activation of HBpin (pin = pinacolate) leading to Tp'Rh(PMe3)(Bpin)H is observed. Similarly, the reaction with Et2SiH2 shows a strong preference for Si-H over C-H activation, generating Tp'Rh(PMe3)(SiEt2H)H. The Rh(Bpin)H and Rh(SiEt2H)H products were stable to heating in benzene in accord with DFT calculations that showed that reaction with benzene is endoergic. The intramolecular competition with PhSiH3 yields a ∼1:4 mixture of Tp'Rh(PMe3)(C6H4SiH3)H and Tp'Rh(PMe3)(SiPhH2)H, respectively. Reaction with pentafluoropyridine generates Tp'Rh(PMe3)(C5NF4)F, while reaction with 2,3,5,6-tetrafluoropyridine yields a mixture of C-H and C-F activated products. Hexafluorobenzene proves unreactive. Crystal structures are reported for B-H, Si-H, and C-F activated products, but in the latter case a bifluoride complex Tp'Rh(PMe3)(C5NF4)(FHF) was crystallized. Intermolecular competition reactions were studied by photoreaction of 1 in C6F6 with benzene and another substrate (HBpin, PhSiH3, or pentafluoropyridine) employing in situ laser photolysis in the NMR probe, resulting in a wide-ranging map of kinetic selectivities. The mechanisms of intramolecular and intermolecular selection are analyzed.

  6. Mathematical modelling in solid mechanics

    CERN Document Server

    Sofonea, Mircea; Steigmann, David

    2017-01-01

    This book presents new research results in multidisciplinary fields of mathematical and numerical modelling in mechanics. The chapters treat the topics: mathematical modelling in solid, fluid and contact mechanics nonconvex variational analysis with emphasis to nonlinear solid and structural mechanics numerical modelling of problems with non-smooth constitutive laws, approximation of variational and hemivariational inequalities, numerical analysis of discrete schemes, numerical methods and the corresponding algorithms, applications to mechanical engineering numerical aspects of non-smooth mechanics, with emphasis on developing accurate and reliable computational tools mechanics of fibre-reinforced materials behaviour of elasto-plastic materials accounting for the microstructural defects definition of structural defects based on the differential geometry concepts or on the atomistic basis interaction between phase transformation and dislocations at nano-scale energetic arguments bifurcation and post-buckling a...

  7. 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...

  8. Nanoscale deformation mechanisms in bone.

    Science.gov (United States)

    Gupta, Himadri S; Wagermaier, Wolfgang; Zickler, Gerald A; Raz-Ben Aroush, D; Funari, Sérgio S; Roschger, Paul; Wagner, H Daniel; Fratzl, Peter

    2005-10-01

    Deformation mechanisms in bone matrix at the nanoscale control its exceptional mechanical properties, but the detailed nature of these processes is as yet unknown. In situ tensile testing with synchrotron X-ray scattering allowed us to study directly and quantitatively the deformation mechanisms at the nanometer level. We find that bone deformation is not homogeneous but distributed between a tensile deformation of the fibrils and a shearing in the interfibrillar matrix between them.

  9. Quantum Mechanics in the Infrared

    CERN Document Server

    Radicevic, Djordje

    2016-01-01

    This paper presents an algebraic formulation of the renormalization group flow in quantum mechanics on flat target spaces. For any interacting quantum mechanical theory, the fixed point of this flow is a theory of classical probability, not a different effective quantum mechanics. Each energy eigenstate of the UV Hamiltonian flows to a probability distribution whose entropy is a natural diagnostic of quantum ergodicity of the original state. These conclusions are supported by various examples worked out in detail.

  10. Mechanical ventilation in neurosurgical patients

    Directory of Open Access Journals (Sweden)

    Keshav Goyal

    2013-01-01

    Full Text Available Mechanical ventilation significantly affects cerebral oxygenation and cerebral blood flow through changes in arterial carbon dioxide levels. Neurosurgical patients might require mechanical ventilation for correction and maintenance of changes in the pulmonary system that occur either due to neurosurgical pathology or following surgery during the acute phase. This review discusses the basics of mechanical ventilation relevant to the neurosurgeon in the day-to-day management of neurosurgical patient requiring artificial support of the respiration.

  11. Gamification of Quantum Mechanics Teaching

    CERN Document Server

    Bjælde, Ole Eggers; Sherson, Jacob

    2015-01-01

    In this small scale study we demonstrate how a gamified teaching setup can be used effectively to support student learning in a quantum mechanics course. The quantum mechanics games were research games, which were played during lectures and the learning was measured with a pretest/posttest method with promising results. The study works as a pilot study to guide the planning of quantum mechanics courses in the future at Aarhus University in Denmark.

  12. Mathematical foundations of quantum mechanics

    CERN Document Server

    Mackey, George W

    2004-01-01

    Designed for students familiar with abstract mathematical concepts but possessing little knowledge of physics, this text focuses on generality and careful formulation rather than problem-solving. Its author, a member of the distinguished National Academy of Science, based this graduate-level text on the course he taught at Harvard University.Opening chapters on classical mechanics examine the laws of particle mechanics; generalized coordinates and differentiable manifolds; oscillations, waves, and Hilbert space; and statistical mechanics. A survey of quantum mechanics covers the old quantum

  13. Mechanical design of DNA nanostructures.

    Science.gov (United States)

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

    2015-04-14

    Structural DNA nanotechnology is a rapidly emerging field that has demonstrated great potential for applications such as single molecule sensing, drug delivery, and templating molecular components. As the applications of DNA nanotechnology expand, a consideration of their mechanical behavior is becoming essential to understand how these structures will respond to physical interactions. This review considers three major avenues of recent progress in this area: (1) measuring and designing mechanical properties of DNA nanostructures, (2) designing complex nanostructures based on imposed mechanical stresses, and (3) designing and controlling structurally dynamic nanostructures. This work has laid the foundation for mechanically active nanomachines that can generate, transmit, and respond to physical cues in molecular systems.

  14. Mechanics lectures on theoretical physics

    CERN Document Server

    Sommerfeld, Arnold Johannes Wilhelm

    1952-01-01

    Mechanics: Lectures on Theoretical Physics, Volume I covers a general course on theoretical physics. The book discusses the mechanics of a particle; the mechanics of systems; the principle of virtual work; and d'alembert's principle. The text also describes oscillation problems; the kinematics, statics, and dynamics of a rigid body; the theory of relative motion; and the integral variational principles of mechanics. Lagrange's equations for generalized coordinates and the theory of Hamilton are also considered. Physicists, mathematicians, and students taking Physics courses will find the book

  15. Statistical mechanics in a nutshell

    CERN Document Server

    Peliti, Luca

    2011-01-01

    Statistical mechanics is one of the most exciting areas of physics today, and it also has applications to subjects as diverse as economics, social behavior, algorithmic theory, and evolutionary biology. Statistical Mechanics in a Nutshell offers the most concise, self-contained introduction to this rapidly developing field. Requiring only a background in elementary calculus and elementary mechanics, this book starts with the basics, introduces the most important developments in classical statistical mechanics over the last thirty years, and guides readers to the very threshold of today

  16. Mechanisms of HSP72 release

    Indian Academy of Sciences (India)

    Alexzander Asea

    2007-04-01

    Currently two mechanisms are recognized by which heat shock proteins (HSP) are released from cells; a passive release mechanism, including necrotic cell death, severe blunt trauma, surgery and following infection with lytic viruses, and an active release mechanism which involves the non classical protein release pathway. HSPs are released both as free HSP and within exosomes. This review covers recent findings on the mechanism by which stress induces the release of HSP72 into the circulation and the biological significance of circulating HSP72 to host defense against disease.

  17. Quantum Mechanics for Electrical Engineers

    CERN Document Server

    Sullivan, Dennis M

    2011-01-01

    The main topic of this book is quantum mechanics, as the title indicates.  It specifically targets those topics within quantum mechanics that are needed to understand modern semiconductor theory.   It begins with the motivation for quantum mechanics and why classical physics fails when dealing with very small particles and small dimensions.  Two key features make this book different from others on quantum mechanics, even those usually intended for engineers:   First, after a brief introduction, much of the development is through Fourier theory, a topic that is at

  18. Activities report in fluid mechanics

    Science.gov (United States)

    1986-10-01

    The research conducted at the Lille Institute of Fluid Mechanics (IMFL) concerns four areas: flight mechanics, structural mechanics, aerodynamics and applied fluid mechanics. Within these four areas, these topics are discussed: characterization of the unsteady pressures on an airfoil in turbulence; adaptation of the Kalman-Rauch filtering-smoothing method to instrumented free spin tests; vulnerability of aircraft fuel tanks; water surface impact; influence of an oscillating spoiler on the surrounding aerodynamic field; gunfiring similarity theory and rules; flow around a cylinder at low Reynolds number by holographic velocimetry and laser Doppler velocimetry; compressible turbulent flow computation; and the wake of wind turbine towers are discussed.

  19. Cell mechanics: integrating cell responses to mechanical stimuli.

    Science.gov (United States)

    Janmey, Paul A; McCulloch, Christopher A

    2007-01-01

    Forces are increasingly recognized as major regulators of cell structure and function, and the mechanical properties of cells are essential to the mechanisms by which cells sense forces, transmit them to the cell interior or to other cells, and transduce them into chemical signals that impact a spectrum of cellular responses. Comparison of the mechanical properties of intact cells with those of the purified cytoskeletal biopolymers that are thought to dominate their elasticity reveal the extent to which the studies of purified systems can account for the mechanical properties of the much more heterogeneous and complex cell. This review summarizes selected aspects of current work on cell mechanics with an emphasis on the structures that are activated in cell-cell contacts, that regulate ion flow across the plasma membrane, and that may sense fluid flow that produces low levels of shear stress.

  20. Mechanical Behaviour of Materials Volume II Fracture Mechanics and Damage

    CERN Document Server

    François, Dominique; Zaoui, André

    2013-01-01

    Designing new structural materials, extending lifetimes and guarding against fracture in service are among the preoccupations of engineers, and to deal with these they need to have command of the mechanics of material behaviour. This ought to reflect in the training of students. In this respect, the first volume of this work deals with elastic, elastoplastic, elastoviscoplastic and viscoelastic behaviours; this second volume continues with fracture mechanics and damage, and with contact mechanics, friction and wear. As in Volume I, the treatment links the active mechanisms on the microscopic scale and the laws of macroscopic behaviour. Chapter I is an introduction to the various damage phenomena. Chapter II gives the essential of fracture mechanics. Chapter III is devoted to brittle fracture, chapter IV to ductile fracture and chapter V to the brittle-ductile transition. Chapter VI is a survey of fatigue damage. Chapter VII is devoted to hydogen embrittlement and to environment assisted cracking, chapter VIII...