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Sample records for aguda irreversible debido

  1. Irreversibility with quantum trajectories.

    PubMed

    Wisniacki, D A; Borondo, F; Benito, R M

    2005-10-01

    Irreversibility is an important issue for many quantum processes. Loschmidt echoes, originally introduced as a way to gauge sensitivity to perturbations in quantum mechanics, have turned out to be a useful tool for its investigation. Following the philosophy supporting this idea, and using quantum trajectories as defined in the causal interpretation of quantum mechanics due to Bohm, we introduce in this paper a more informative alternative measure for irreversibility. The method is applied to the Bunimovich stadium billiard, a paradigmatic example of chaotic system, that constitutes an excellent model for mesoscopic devices.

  2. Irreversible quantum baker map.

    PubMed

    Łoziński, Artur; Pakoński, Prot; Zyczkowski, Karol

    2002-12-01

    We propose a generalization of the model of classical baker map on the torus, in which the images of two parts of the phase space do overlap. This transformation is irreversible and cannot be quantized by means of a unitary Floquet operator. A corresponding quantum system is constructed as a completely positive map acting in the space of density matrices. We investigate spectral properties of this superoperator and their link with the increase of the entropy of initially pure states.

  3. Irreversible magnetic switch

    SciTech Connect

    Karnowsky, M.M.; Yost, F.G.

    1991-12-31

    This invention is comprised of an irreversible magnetic switch containing a ferromagnetic amorphous metal having a predetermined crystallization temperature in its inductor magnetic path. With the incorporation of such material, the magnetic properties after cooling from a high temperature excursion above its crystallization temperature are only a fraction of the original value. The difference is used to provide a safety feature in the magnetic switch.

  4. Irreversible Simulated Tempering

    NASA Astrophysics Data System (ADS)

    Sakai, Yuji; Hukushima, Koji

    2016-10-01

    An extended ensemble Monte Carlo algorithm is proposed by introducing a violation of the detailed balance condition to the update scheme of the inverse temperature in simulated tempering. Our method, irreversible simulated tempering, is constructed based on the framework of the skew detailed balance condition. By applying this method to the ferromagnetic Ising model in two dimensions on a square lattice as a benchmark, the dynamical behavior of the inverse temperature and an autocorrelation function of the magnetization are studied numerically. It is found that the relaxation dynamics of the inverse temperature changes qualitatively from diffusive to ballistic by violating the detailed balance condition. Consequently, the autocorrelation time of magnetization is several times smaller than that for the conventional algorithm satisfying the detailed balance condition.

  5. Intrinsically irreversible heat engine

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1984-01-01

    A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. the second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat.

  6. Intrinsically irreversible heat engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1984-12-25

    A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. The second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat. 11 figs.

  7. Intrinsically irreversible heat engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1984-01-01

    A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. The second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat.

  8. Information symmetries in irreversible processes

    NASA Astrophysics Data System (ADS)

    Ellison, Christopher J.; Mahoney, John R.; James, Ryan G.; Crutchfield, James P.; Reichardt, Jörg

    2011-09-01

    We study dynamical reversibility in stationary stochastic processes from an information-theoretic perspective. Extending earlier work on the reversibility of Markov chains, we focus on finitary processes with arbitrarily long conditional correlations. In particular, we examine stationary processes represented or generated by edge-emitting, finite-state hidden Markov models. Surprisingly, we find pervasive temporal asymmetries in the statistics of such stationary processes. As a consequence, the computational resources necessary to generate a process in the forward and reverse temporal directions are generally not the same. In fact, an exhaustive survey indicates that most stationary processes are irreversible. We study the ensuing relations between model topology in different representations, the process's statistical properties, and its reversibility in detail. A process's temporal asymmetry is efficiently captured using two canonical unifilar representations of the generating model, the forward-time and reverse-time ɛ-machines. We analyze example irreversible processes whose ɛ-machine representations change size under time reversal, including one which has a finite number of recurrent causal states in one direction, but an infinite number in the opposite. From the forward-time and reverse-time ɛ-machines, we are able to construct a symmetrized, but nonunifilar, generator of a process—the bidirectional machine. Using the bidirectional machine, we show how to directly calculate a process's fundamental information properties, many of which are otherwise only poorly approximated via process samples. The tools we introduce and the insights we offer provide a better understanding of the many facets of reversibility and irreversibility in stochastic processes.

  9. Niche Applications of Irreversible Electroporation.

    PubMed

    Bhatia, Shivank S; Arya, Rahul; Narayanan, Govindarajan

    2015-09-01

    Irreversible electroporation (IRE) induces cell death by exposing it to high-voltage, low-energy DC current pulses. The mechanism of cell death and healing is a departure from the other existing technologies such as radiofrequency ablation, microwave ablation, and cryoablation. These thermal ablative technologies have several applications in oncology but have limitations that have also been established. IRE has shown promise to overcome some of these limitations and has enabled the use of an ablative technology in treating lesions close to the bile ducts and vasculature and in organs such as the pancreas. This review highlights some of the niche applications of IRE and the data so far.

  10. Irreversible gettering of thionyl chloride

    SciTech Connect

    LeRoy Whinnery; Steve Goods; George Buffleben; Tim Sheppodd

    1999-11-01

    The authors have successfully demonstrated the irreversible gettering of SOCl{sub 2} by ZnO/ASZMTEDA carbon over a modest temperature range. While thionyl chloride decomposition was slow below {minus}20 C, lower temperatures are expected to be less of a problem than at higher temperatures. The approximately 30 cc of thionyl chloride in a typical D-cell would require 50 g of ZnO and 107 g of ASZMTEDA carbon. Fortunately, since it is unlikely to happen at all, it is common practice to assume only one cell will fail (leak) in a given battery pack. So, one charge of getter can protect the whole battery pack. In summary, ZnO/ASZMTEDA carbon fulfills all of the requirements of an ideal getter including: irreversible binding or reaction with SOCl{sub 2}, high volumetric uptake capacity, high efficiency, non-volatile, air stable, insensitive to poisoning, non-toxic, cheap, non-corrosive, and the gettering product is not a liquid or oil that could block further flow or accessibility. Future work in this area includes incorporation of the ZnO and carbon into a structural open-celled porous monolith, as well as, gettering for other types of batteries (e.g., Li/MnO{sub 2}).

  11. Lyapunov decay in quantum irreversibility.

    PubMed

    García-Mata, Ignacio; Roncaglia, Augusto J; Wisniacki, Diego A

    2016-06-13

    The Loschmidt echo--also known as fidelity--is a very useful tool to study irreversibility in quantum mechanics due to perturbations or imperfections. Many different regimes, as a function of time and strength of the perturbation, have been identified. For chaotic systems, there is a range of perturbation strengths where the decay of the Loschmidt echo is perturbation independent, and given by the classical Lyapunov exponent. But observation of the Lyapunov decay depends strongly on the type of initial state upon which an average is carried out. This dependence can be removed by averaging the fidelity over the Haar measure, and the Lyapunov regime is recovered, as has been shown for quantum maps. In this work, we introduce an analogous quantity for systems with infinite dimensional Hilbert space, in particular the quantum stadium billiard, and we show clearly the universality of the Lyapunov regime. PMID:27140966

  12. [Circulatory survival of irreversible comas].

    PubMed

    Cartier, F; Chevet, D; Garré, M; Launois, B; Thomas, R; Le Pollès, R

    1975-01-18

    On the basis of a series of 53 cases of irreversible coma maintained in circulatory survival with the aim of removing the kidneys, the authors discuss the mode of treatment, with particular reference to the intravenous fluids used and the use of medications influencing the circulation. Fluid and electrolytes given must be adjusted hourly to ensure the exact replacement of urinary losses. Isoprotenerol is the only medication usually necessary. In the event of circulatory insufficiency, which is difficult to foresee and hence prevent, immediate volume expansion in a short a time as possible and isoprotenerol most frequently correct the situation (14 out of 17 cases). Thus effective circulation may be maintained until the kidneys are removed (48 out of 53 cases). 92 p.cent of the grafted kidneys functioned from the first day onwards. PMID:1093120

  13. Variational principles of irreversible processes

    NASA Astrophysics Data System (ADS)

    Ichiyanagi, Masakazu

    1994-07-01

    This article reviews developments of variational principles in the study of irreversible processes during the past three decades or so. The variational principles we consider here are related to entropy production. The purpose of this article is to explicate that we can formulate a variational principle which relates the transport coefficients to microscopic dynamics of fluctuations. The quantum variational principle restricts the nonequilibrium density matrix to a class conforming to the requirement demanded by the second law of thermodynamics. These are various kinds of variational principles according to different stages of a macroscopic system. The three stages are known, which are dynamical, kinetic, and thermodynamical stages. The relationships among these variational principles are discussed from the point of view of the contraction of information about irrelevant components. Nakano's variational principle has close similarity to the Lippmann-Schwinger theory of scattering, in which some incoming and outgoing disturbances have to be considered in a pair. It is also shown that the variational principle of Onsager's type can be reformulated in the form of Hamilton's principle if a generalization of Hamilton's principle proposed by Djukic and Vujanovic is used. A variational principle in the diagrammatic method is also reviewed, which utilizes the generalized Ward-Takahashi relations.

  14. Irritation of ocular tissue by irreversible hydrocolloids.

    PubMed

    Moergeli, J R; Fraleigh, E M; Ostrowski, J S; Pelleu, G B

    1985-08-01

    Two ophthalmic and two dental irreversible hydrocolloid materials were tested on rabbit conjunctivae to determine histologically their potential to irritate these tissues. Each of the four impression materials elicited nearly the same amount of inflammatory response. The differences between the response of the controls and the response to Ophthalmic Mold-Eye, Jelset Special Formula, and Kerr Alignate Type II were significant. These results indicate that certain dental irreversible hydrocolloids may be used for ocular prostheses but that they should be used with caution because of the inflammation caused by irreversible hydrocolloids.

  15. Irreversible thermodynamics of Poisson processes with reaction.

    PubMed

    Méndez, V; Fort, J

    1999-11-01

    A kinetic model is derived to study the successive movements of particles, described by a Poisson process, as well as their generation. The irreversible thermodynamics of this system is also studied from the kinetic model. This makes it possible to evaluate the differences between thermodynamical quantities computed exactly and up to second-order. Such differences determine the range of validity of the second-order approximation to extended irreversible thermodynamics.

  16. Irreversible thermodynamics of Poisson processes with reaction

    NASA Astrophysics Data System (ADS)

    Méndez, Vicenç; Fort, Joaquim

    1999-11-01

    A kinetic model is derived to study the successive movements of particles, described by a Poisson process, as well as their generation. The irreversible thermodynamics of this system is also studied from the kinetic model. This makes it possible to evaluate the differences between thermodynamical quantities computed exactly and up to second-order. Such differences determine the range of validity of the second-order approximation to extended irreversible thermodynamics.

  17. Heat devices in nonlinear irreversible thermodynamics

    NASA Astrophysics Data System (ADS)

    Izumida, Y.; Okuda, K.; Roco, J. M. M.; Hernández, A. Calvo

    2015-05-01

    We present results obtained by using nonlinear irreversible models for heat devices. In particular, we focus on the global performance characteristics, the maximum efficiency and the efficiency at maximum power regimes for heat engines, and the maximum coefficient of performance (COP) and the COP at maximum cooling power regimes for refrigerators. We analyze the key role played by the interplay between irreversibilities coming from heat leaks and internal dissipations. We also discuss the relationship between these results and those obtained by different models.

  18. Enfermedad diarreica aguda por Escherichia coli patógenas en Colombia

    PubMed Central

    Gómez-Duarte, Oscar G.

    2014-01-01

    Resumen Las cepas de E. coli patógenas intestinales son causas importantes de la enfermedad diarreica aguda (EDA) en niños menores de 5 años en América Latina, África y Asia y están asociadas a alta mortalidad en niños en las comunidades más pobres de África y el Sudeste Asiático. Estudios sobre el papel de las E. coli patógenas intestinales en la EDA infantil en Colombia y otros países de América Latina son limitados debido a la carencia de ensayos para detección de estos patógenos en los laboratorios clínicos de centros de salud. Estudios recientes han reportado la detección de E. coli patógenas intestinales en Colombia, siendo la E. coli enterotoxigénica la cepa más frecuentemente asociada a diarrea en niños menores de 5 años. Otros patógenos detectados en estos pacientes incluyen las E. coli enteroagregativa, enteropatógena, productora de toxina Shiga, y de adherencia difusa. Con base en estudios que reportan la presencia de E. coli productora de toxina Shiga y E. coli enteroagregativa en carnes y vegetales en supermercados, se cree que productos alimentarios contaminados contribuyen a la transmisión de estos patógenos y a la infección del huésped susceptible. Más estudios son necesarios para evaluar los mecanismos de transmisión, el impacto en la epidemiologia de la EDA, y las pautas de manejo y prevención de estos patógenos que afectan la población pediátrica en Colombia. PMID:25491457

  19. [Irreversible image compression in radiology. Current status].

    PubMed

    Pinto dos Santos, D; Jungmann, F; Friese, C; Düber, C; Mildenberger, P

    2013-03-01

    Due to increasing amounts of data in radiology methods for image compression appear both economically and technically interesting. Irreversible image compression allows markedly higher reduction of data volume in comparison with reversible compression algorithms but is, however, accompanied by a certain amount of mathematical and visual loss of information. Various national and international radiological societies have published recommendations for the use of irreversible image compression. The degree of acceptable compression varies across modalities and regions of interest.The DICOM standard supports JPEG, which achieves compression through tiling, DCT/DWT and quantization. Although mathematical loss due to rounding up errors and reduction of high frequency information occurs this results in relatively low visual degradation.It is still unclear where to implement irreversible compression in the radiological workflow as only few studies analyzed the impact of irreversible compression on specialized image postprocessing. As long as this is within the limits recommended by the German Radiological Society irreversible image compression could be implemented directly at the imaging modality as it would comply with § 28 of the roentgen act (RöV). PMID:23456043

  20. N-Alkoxyheterocycles As Irreversible Photooxidants†

    PubMed Central

    Wosinska, Zofia M.; Stump, Faye L.; Ranjan, Rajeev; Lorance, Edward D.; Finley, GeNita N.; Patel, Priya P.; Khawaja, Muzamil A.; Odom, Katie L.; Kramer, Wolfgang H.; Gould, Ian R.

    2015-01-01

    Irreversible photooxidation based on N–O bond fragmentation is demonstrated for N-methoxyheterocycles in both the singlet and triplet excited state manifolds. The energetic requirements for bond fragmentation are studied in detail. Bond fragmentation in the excited singlet manifold is possible for ππ* singlet states with energies significantly larger than the N–O bond dissociation energy of ca 55 kcal mol−1. For the nπ* triplet states, N–O bond fragmentation does not occur in the excited state for orbital overlap and energetic reasons. Irreversible photooxidation occurs in the singlet states by bond fragmentation followed by electron transfer. Irreversible photooxidation occurs in the triplet states via bimolecular electron transfer to the donor followed by bond fragmentation. Using these two sensitization schemes, donors can be irreversibly oxidized with oxidation potentials ranging from ca 1.6–2.2 V vs SCE. The corresponding N-ethylheterocycles are characterized as conventional reversible photooxidants in their triplet states. The utility of these sensitizers is demonstrated by irreversibly generating the guanosine radical cation in buffered aqueous solution. PMID:24354634

  1. Emergent irreversibility and entanglement spectrum statistics.

    PubMed

    Chamon, Claudio; Hamma, Alioscia; Mucciolo, Eduardo R

    2014-06-20

    We study the problem of irreversibility when the dynamical evolution of a many-body system is described by a stochastic quantum circuit. Such evolution is more general than a Hamiltonian one, and since energy levels are not well defined, the well-established connection between the statistical fluctuations of the energy spectrum and irreversibility cannot be made. We show that the entanglement spectrum provides a more general connection. Irreversibility is marked by a failure of a disentangling algorithm and is preceded by the appearance of Wigner-Dyson statistical fluctuations in the entanglement spectrum. This analysis can be done at the wave-function level and offers an alternative route to study quantum chaos and quantum integrability.

  2. Entropy production in irreversible processes with friction.

    PubMed

    Bizarro, João P S

    2008-08-01

    Established expressions for entropy production in irreversible processes are generalized to include friction explicitly, as a source of irreversibility in the interaction between a system and its surroundings. The net amount of heat delivered to the system does not come now only from the reservoir, but may have an additional component coming from the work done against friction forces and dissipated as heat. To avoid ambiguities in interpreting the different contributions to entropy increase, the latter is also written in terms of the heat directly exchanged between the system and surroundings and of the fraction of frictional work that is lost in the system. PMID:18850816

  3. Efficiency of Rectification: Reversible vs. Irreversible Regimes

    NASA Astrophysics Data System (ADS)

    Sokolov, I. M.

    2002-11-01

    Both man-made locomotive devices and molecular motors use gears to transform a reciprocating motion into a directed one. One of the most common gears is a rectifier, a mechanically irreversible appliance. The maximal energetic efficiency of an isothermic gear is bounded by unity, as a consequence of the Second Law. However, approaching this ideal efficiency does not imply approaching reversibility. We discuss what properties of a rectifier mostly influence the transduction efficiency and show that an appliance which locks under backward force is just the one which can approach the ideal efficiency either in the reversible or in the irreversible regime.

  4. Time and Irreversibility in AN Accelerating Universe

    NASA Astrophysics Data System (ADS)

    Romero, Gustavo E.; Pérez, Daniela

    It is a remarkable fact that all processes occurring in the observable universe are irreversible, whereas the equations through which the fundamental laws of physics are formulated are invariant under time reversal. The emergence of irreversibility from the fundamental laws has been a topic of consideration by physicists, astronomers and philosophers since Boltzmann's formulation of his famous "H" theorem. In this paper, we shall discuss some aspects of this problem and its connection with the dynamics of spacetime, within the framework of modern cosmology. We conclude that the existence of cosmological horizons allows a coupling of the global state of the universe with the local events determined through electromagnetic processes.

  5. Pilot Decision-Making in Irreversible Emergencies

    ERIC Educational Resources Information Center

    Winter, Scott R.

    2013-01-01

    The purpose of this study was to determine if a reflexive learning treatment utilizing select case studies could enhance the decision-making of pilots who encounter an irreversible emergency. Participants, who consisted of members of the subject university's professional pilot program, were divided into either a control or experimental group and…

  6. Absorption media for irreversibly gettering thionyl chloride

    DOEpatents

    Buffleben, George; Goods, Steven H.; Shepodd, Timothy; Wheeler, David R.; Whinnery, Jr., LeRoy

    2002-01-01

    Thionyl chloride is a hazardous and reactive chemical used as the liquid cathode in commercial primary batteries. Contrary to previous thinking, ASZM-TEDA.RTM. carbon (Calgon Corporation) reversibly absorbs thionyl chloride. Thus, several candidate materials were examined as irreversible getters for thionyl chloride. The capacity, rate and effect of temperature were also explored. A wide variety of likely materials were investigated through screening experiments focusing on the degree of heat generated by the reaction as well as the material absorption capacity and irreversibility, in order to help narrow the group of possible getter choices. More thorough, quantitative measurements were performed on promising materials. The best performing getter was a mixture of ZnO and ASZM-TEDA.RTM. carbon. In this example, the ZnO reacts with thionyl chloride to form ZnCl.sub.2 and SO.sub.2. The SO.sub.2 is then irreversibly gettered by ASZM-TEDA.RTM. carbon. This combination of ZnO and carbon has a high capacity, is irreversible and functions effectively above -20.degree. C.

  7. Markov Chain Monte Carlo and Irreversibility

    NASA Astrophysics Data System (ADS)

    Ottobre, Michela

    2016-06-01

    Markov Chain Monte Carlo (MCMC) methods are statistical methods designed to sample from a given measure π by constructing a Markov chain that has π as invariant measure and that converges to π. Most MCMC algorithms make use of chains that satisfy the detailed balance condition with respect to π; such chains are therefore reversible. On the other hand, recent work [18, 21, 28, 29] has stressed several advantages of using irreversible processes for sampling. Roughly speaking, irreversible diffusions converge to equilibrium faster (and lead to smaller asymptotic variance as well). In this paper we discuss some of the recent progress in the study of nonreversible MCMC methods. In particular: i) we explain some of the difficulties that arise in the analysis of nonreversible processes and we discuss some analytical methods to approach the study of continuous-time irreversible diffusions; ii) most of the rigorous results on irreversible diffusions are available for continuous-time processes; however, for computational purposes one needs to discretize such dynamics. It is well known that the resulting discretized chain will not, in general, retain all the good properties of the process that it is obtained from. In particular, if we want to preserve the invariance of the target measure, the chain might no longer be reversible. Therefore iii) we conclude by presenting an MCMC algorithm, the SOL-HMC algorithm [23], which results from a nonreversible discretization of a nonreversible dynamics.

  8. A new microscopic level of irreversibility

    SciTech Connect

    Prigogine, I.

    1987-01-01

    In this paper, the non-exponential decay is analyzed with the help of simple computer experiments performed by T. Petrosky, simulating classical radiation damping. The non-exponential decay is studied and shown to depend on the preparation of the system. However, whatever the initial preparation, the system reaches the decay predicted by classical radiation theory after a short time we call the Zeno's time. The similitude of Petrosky's results with computer experiments for the approach to equilibrium in many-body systems is emphasized. However, while there one deals with times which are multiple of the relaxation time, the irreversibility manifest in radiation theory occurs always over a much shorter time scale, the Zeno's time. In atomic systems, this would be a time order of 10/sup /minus/18/ seconds. These results are of great interest for the understanding of the microscopic mechanism of radiation. Let us consider a charged oscillator. In a first stage, this oscillator has to produce the field oscillators to which it may transfer energy through the usual resonance mechanism. Radiation appears therefore as a kind of non linear autocatalytic process, involving a self-organization mechanism. The behavior during the Zeno period can be explained easily in terms of subdynamics as introduced by the Brussel's group. We see that there is no transition from reversibility to irreversibility. Irreversible processes start at the very moment at which the system is prepared. It is important to stress that an unstable particle is itself the result of irreversible processes. As a result, an unstable particle (or an excited atomic state) can no more be described in terms of wave functions, as irreversible processes are not included in Schroedinger's equation. 14 refs., 3 figs.

  9. Multiscale multifractal time irreversibility analysis of stock markets

    NASA Astrophysics Data System (ADS)

    Jiang, Chenguang; Shang, Pengjian; Shi, Wenbin

    2016-11-01

    Time irreversibility is one of the most important properties of nonstationary time series. Complex time series often demonstrate even multiscale time irreversibility, such that not only the original but also coarse-grained time series are asymmetric over a wide range of scales. We study the multiscale time irreversibility of time series. In this paper, we develop a method called multiscale multifractal time irreversibility analysis (MMRA), which allows us to extend the description of time irreversibility to include the dependence on the segment size and statistical moments. We test the effectiveness of MMRA in detecting multifractality and time irreversibility of time series generated from delayed Henon map and binomial multifractal model. Then we employ our method to the time irreversibility analysis of stock markets in different regions. We find that the emerging market has higher multifractality degree and time irreversibility compared with developed markets. In this sense, the MMRA method may provide new angles in assessing the evolution stage of stock markets.

  10. Irreversible enzyme inhibition kinetics and drug-drug interactions.

    PubMed

    Mohutsky, Michael; Hall, Stephen D

    2014-01-01

    This chapter describes the types of irreversible inhibition of drug-metabolizing enzymes and the methods commonly employed to quantify the irreversible inhibition and subsequently predict the extent and time course of clinically important drug-drug interactions.

  11. Irreversible thermal denaturation of Torpedo californica acetylcholinesterase.

    PubMed Central

    Kreimer, D. I.; Shnyrov, V. L.; Villar, E.; Silman, I.; Weiner, L.

    1995-01-01

    Thermal denaturation of Torpedo californica acetylcholinesterase, a disulfide-linked homodimer with 537 amino acids in each subunit, was studied by differential scanning calorimetry. It displays a single calorimetric peak that is completely irreversible, the shape and temperature maximum depending on the scan rate. Thus, thermal denaturation of acetylcholinesterase is an irreversible process, under kinetic control, which is described well by the two-state kinetic scheme N-->D, with activation energy 131 +/- 8 kcal/mol. Analysis of the kinetics of denaturation in the thermal transition temperature range, by monitoring loss of enzymic activity, yields activation energy of 121 +/- 20 kcal/mol, similar to the value obtained by differential scanning calorimetry. Thermally denatured acetylcholinesterase displays spectroscopic characteristics typical of a molten globule state, similar to those of partially unfolded enzyme obtained by modification with thiol-specific reagents. Evidence is presented that the partially unfolded states produced by the two different treatments are thermodynamically favored relative to the native state. PMID:8563632

  12. Intracranial nonthermal irreversible electroporation: in vivo analysis.

    PubMed

    Garcia, Paulo A; Rossmeisl, John H; Neal, Robert E; Ellis, Thomas L; Olson, John D; Henao-Guerrero, Natalia; Robertson, John; Davalos, Rafael V

    2010-07-01

    Nonthermal irreversible electroporation (NTIRE) is a new minimally invasive technique to treat cancer. It is unique because of its nonthermal mechanism of tumor ablation. Intracranial NTIRE procedures involve placing electrodes into the targeted area of the brain and delivering a series of short but intense electric pulses. The electric pulses induce irreversible structural changes in cell membranes, leading to cell death. We correlated NTIRE lesion volumes in normal brain tissue with electric field distributions from comprehensive numerical models. The electrical conductivity of brain tissue was extrapolated from the measured in vivo data and the numerical models. Using this, we present results on the electric field threshold necessary to induce NTIRE lesions (495-510 V/cm) in canine brain tissue using 90 50-mus pulses at 4 Hz. Furthermore, this preliminary study provides some of the necessary numerical tools for using NTIRE as a brain cancer treatment. We also computed the electrical conductivity of brain tissue from the in vivo data (0.12-0.30 S/m) and provide guidelines for treatment planning and execution. Knowledge of the dynamic electrical conductivity of the tissue and electric field that correlates to lesion volume is crucial to ensure predictable complete NTIRE treatment while minimizing damage to surrounding healthy tissue. PMID:20668843

  13. On phylogenetic tests of irreversible evolution.

    PubMed

    Goldberg, Emma E; Igić, Boris

    2008-11-01

    "Dollo's law" states that, following loss, a complex trait cannot reevolve in an identical manner. Although the law has previously fallen into disrepute, it has only recently been challenged with statistical phylogenetic methods. We employ simulation studies of an irreversible binary character to show that rejections of Dollo's law based on likelihood-ratio tests of transition rate constraints or on reconstructions of ancestral states are frequently incorrect. We identify two major causes of errors: incorrect assignment of root state frequencies, and neglect of the effect of the character state on rates of speciation and extinction. Our findings do not necessarily overturn the conclusions of phylogenetic studies claiming reversals, but we demonstrate devastating flaws in the methods that are the foundation of all such studies. Furthermore, we show that false rejections of Dollo's law can be reduced by the use of appropriate existing models and model selection procedures. More powerful tests of irreversibility require data beyond phylogenies and character states of extant taxa, and we highlight empirical work that incorporates additional information.

  14. Probabilistic Gompertz model of irreversible growth.

    PubMed

    Bardos, D C

    2005-05-01

    Characterizing organism growth within populations requires the application of well-studied individual size-at-age models, such as the deterministic Gompertz model, to populations of individuals whose characteristics, corresponding to model parameters, may be highly variable. A natural approach is to assign probability distributions to one or more model parameters. In some contexts, size-at-age data may be absent due to difficulties in ageing individuals, but size-increment data may instead be available (e.g., from tag-recapture experiments). A preliminary transformation to a size-increment model is then required. Gompertz models developed along the above lines have recently been applied to strongly heterogeneous abalone tag-recapture data. Although useful in modelling the early growth stages, these models yield size-increment distributions that allow negative growth, which is inappropriate in the case of mollusc shells and other accumulated biological structures (e.g., vertebrae) where growth is irreversible. Here we develop probabilistic Gompertz models where this difficulty is resolved by conditioning parameter distributions on size, allowing application to irreversible growth data. In the case of abalone growth, introduction of a growth-limiting biological length scale is then shown to yield realistic length-increment distributions.

  15. Irreversible heavy chain transfer to chondroitin.

    PubMed

    Lauer, Mark E; Hascall, Vincent C; Green, Dixy E; DeAngelis, Paul L; Calabro, Anthony

    2014-10-17

    We have recently demonstrated that the transfer of heavy chains (HCs) from inter-α-inhibitor, via the enzyme TSG-6 (tumor necrosis factor-stimulated gene 6), to hyaluronan (HA) oligosaccharides is an irreversible event in which subsequent swapping of HCs between HA molecules does not occur. We now describe our results of HC transfer experiments to chondroitin sulfate A, chemically desulfated chondroitin, chemoenzymatically synthesized chondroitin, unsulfated heparosan, heparan sulfate, and alginate. Of these potential HC acceptors, only chemically desulfated chondroitin and chemoenzymatically synthesized chondroitin were HC acceptors. The kinetics of HC transfer to chondroitin was similar to HA. At earlier time points, HCs were more widely distributed among the different sizes of chondroitin chains. As time progressed, the HCs migrated to lower molecular weight chains of chondroitin. Our interpretation is that TSG-6 swaps the HCs from the larger, reversible sites on chondroitin chains, which function as HC acceptors, onto smaller chondroitin chains, which function as irreversible HC acceptors. HCs transferred to smaller chondroitin chains were unable to be swapped off the smaller chondroitin chains and transferred to HA. HCs transferred to high molecular weight HA were unable to be swapped onto chondroitin. We also present data that although chondroitin was a HC acceptor, HA was the preferred acceptor when chondroitin and HA were in the same reaction mixture.

  16. Magnetic Irreversibility in VO2/Ni Bilayers

    NASA Astrophysics Data System (ADS)

    de La Venta, Jose; Lauzier, Josh; Sutton, Logan

    The temperature dependence of the coercivity and magnetization of VO2/Ni bilayers was studied. VO2 exhibits a well-known Structural Phase Transition (SPT) at 330-340 K, from a low temperature monoclinic (M) to a high temperature rutile (R) structure. The SPT of VO2 induces an inverse magnetoelastic effect that strongly modifies the coercivity and magnetization of the Ni films. In addition, the growth conditions allow tuning of the magnetic properties. Ni films deposited on top of VO2 (M) show an irreversible change in the coercivity after the first cycle through the high temperature phase, with a corresponding change in the surface morphology of VO2. On the other hand, the Ni films grown on top of VO2 (R) do not show this irreversibility. These results indicate that properties of magnetic films are strongly affected by the strain induced by materials that undergo SPT and that it is possible to control the magnetic properties by tuning the growth conditions.

  17. Irreversible sediment formation in green tea infusions.

    PubMed

    Xu, Yong-Quan; Chen, Gen-Sheng; Wang, Qiu-Shuang; Yuan, Hai-Bo; Feng, Chun-Hong; Yin, Jun-Feng

    2012-03-01

    The formation of irreversible tea sediment (IRS) and its chemical components in green tea infusions were investigated. The results showed that the amounts of IRS in the green tea infusions from various tea cultivars ranged from 0.10 to 1.47 mg/mL. The amount of IRS was influenced remarkably by the chemical components in the green tea infusion. Principal component analysis and regression analysis indicated that gallated catechins, Mn, Ca, caffeine, Na, and (-)-gallocatechin gallate (GCG) were the principal components. IRS (mg/mL) = -4.226 + 0.275 gallated catechins + 79.551 Na + 7.321 Mn + 21.055 Ca + 0.513 caffeine - 0.129 GCG (R2 = 0.697). The contents of the main chemical components in the reversible tea sediment (RTS) and IRS were markedly different, especially the minerals. Large amount of minerals participated in the formation of irreversible green tea sediment. The amount of IRS increased with the extraction temperature. PMID:22329921

  18. Irreversible electroporation: state of the art

    PubMed Central

    Wagstaff, Peter GK; Buijs, Mara; van den Bos, Willemien; de Bruin, Daniel M; Zondervan, Patricia J; de la Rosette, Jean JMCH; Laguna Pes, M Pilar

    2016-01-01

    The field of focal ablative therapy for the treatment of cancer is characterized by abundance of thermal ablative techniques that provide a minimally invasive treatment option in selected tumors. However, the unselective destruction inflicted by thermal ablation modalities can result in damage to vital structures in the vicinity of the tumor. Furthermore, the efficacy of thermal ablation intensity can be impaired due to thermal sink caused by large blood vessels in the proximity of the tumor. Irreversible electroporation (IRE) is a novel ablation modality based on the principle of electroporation or electropermeabilization, in which electric pulses are used to create nanoscale defects in the cell membrane. In theory, IRE has the potential of overcoming the aforementioned limitations of thermal ablation techniques. This review provides a description of the principle of IRE, combined with an overview of in vivo research performed to date in the liver, pancreas, kidney, and prostate. PMID:27217767

  19. Exergetic sustainability evaluation of irreversible Carnot refrigerator

    NASA Astrophysics Data System (ADS)

    Açıkkalp, Emin

    2015-10-01

    Purpose of this paper is to assess irreversible refrigeration cycle by using exergetic sustainability index. In literature, there is no application of exergetic sustainability index for the refrigerators and, indeed, this index has not been derived for refrigerators. In this study, exergetic sustainability indicator is presented for the refrigeration cycle and its relationships with other thermodynamics parameters including COP, exergy efficiency, cooling load, exergy destruction, ecological function and work input are investigated. Calculations are conducted for endoreversible and reversible cycles and then results obtained from the ecological function are compared. It is found that exergy efficiency, exergetic sustainable index reduce 47.595% and 59.689% and rising at the COP is 99.888% is obtained for endoreversible cycle. Similarly, exergy efficiency and exergetic sustainability index reduce 90.163% and 93.711% and rising of the COP is equal to 99.362%.

  20. Irreversible electroporation: state of the art.

    PubMed

    Wagstaff, Peter Gk; Buijs, Mara; van den Bos, Willemien; de Bruin, Daniel M; Zondervan, Patricia J; de la Rosette, Jean Jmch; Laguna Pes, M Pilar

    2016-01-01

    The field of focal ablative therapy for the treatment of cancer is characterized by abundance of thermal ablative techniques that provide a minimally invasive treatment option in selected tumors. However, the unselective destruction inflicted by thermal ablation modalities can result in damage to vital structures in the vicinity of the tumor. Furthermore, the efficacy of thermal ablation intensity can be impaired due to thermal sink caused by large blood vessels in the proximity of the tumor. Irreversible electroporation (IRE) is a novel ablation modality based on the principle of electroporation or electropermeabilization, in which electric pulses are used to create nanoscale defects in the cell membrane. In theory, IRE has the potential of overcoming the aforementioned limitations of thermal ablation techniques. This review provides a description of the principle of IRE, combined with an overview of in vivo research performed to date in the liver, pancreas, kidney, and prostate.

  1. Performance of an irreversible quantum Carnot engine with spin 12.

    PubMed

    Wu, Feng; Chen, Lingen; Wu, Shuang; Sun, Fengrui; Wu, Chih

    2006-06-01

    The purpose of this paper is to investigate the effect of quantum properties of the working medium on the performance of an irreversible Carnot cycle with spin 12. The optimal relationship between the dimensionless power output P* versus the efficiency eta for the irreversible quantum Carnot engine with heat leakage and other irreversible losses is derived. Especially, the performances of the engine at low temperature limit and at high temperature limit are discussed.

  2. Guinea pig ductus arteriosus. II - Irreversible closure after birth.

    NASA Technical Reports Server (NTRS)

    Fay, F. S.; Cooke, P. H.

    1972-01-01

    To investigate the mechanism underlying irreversibility of ductal closure after birth, studies were undertaken to determine the exact time course for the onset of irreversible closure of the guinea pig ductus arteriosus. Parallel studies of the reactivity of ductal smooth muscle to oxygen and studies of the postpartum cellular changes within the vessel were also carried out.

  3. Conservation-dissipation formalism of irreversible thermodynamics

    NASA Astrophysics Data System (ADS)

    Zhu, Yi; Hong, Liu; Yang, Zaibao; Yong, Wen-An

    2015-06-01

    We propose a conservation-dissipation formalism (CDF) for coarse-grained descriptions of irreversible processes. This formalism is based on a stability criterion for non-equilibrium thermodynamics. The criterion ensures that non-equilibrium states tend to equilibrium in long time. As a systematic methodology, CDF provides a feasible procedure in choosing non-equilibrium state variables and determining their evolution equations. The equations derived in CDF have a unified elegant form. They are globally hyperbolic, allow a convenient definition of weak solutions, and are amenable to existing numerics. More importantly, CDF is a genuinely nonlinear formalism and works for systems far away from equilibrium. With this formalism, we formulate novel thermodynamics theories for heat conduction in rigid bodies and non-isothermal compressible Maxwell fluid flows as two typical examples. In these examples, the non-equilibrium variables are exactly the conjugate variables of the heat fluxes or stress tensors. The new theory generalizes Cattaneo's law or Maxwell's law in a regularized and nonlinear fashion.

  4. Simulations of kinetically irreversible protein aggregate structure.

    PubMed Central

    Patro, S Y; Przybycien, T M

    1994-01-01

    We have simulated the structure of kinetically irreversible protein aggregates in two-dimensional space using a lattice-based Monte-Carlo routine. Our model specifically accounts for the intermolecular interactions between hydrophobic and hydrophilic protein surfaces and a polar solvent. The simulations provide information about the aggregate density, the types of inter-monomer contacts and solvent content within the aggregates, the type and extent of solvent exposed perimeter, and the short- and long-range order all as a function of (i) the extent of monomer hydrophobic surface area and its distribution on the model protein surface and (ii) the magnitude of the hydrophobic-hydrophobic contact energy. An increase in the extent of monomer hydrophobic surface area resulted in increased aggregate densities with concomitant decreased system free energies. These effects are accompanied by increases in the number of hydrophobic-hydrophobic contacts and decreases in the solvent-exposed hydrophobic surface area of the aggregates. Grouping monomer hydrophobic surfaces in a single contiguous stretch resulted in lower aggregate densities and lower short range order. More favorable hydrophobic-hydrophobic contact energies produced structures with higher densities but the number of unfavorable protein-protein contacts was also observed to increase; greater configurational entropy produced the opposite effect. Properties predicted by our model are in good qualitative agreement with available experimental observations. Images FIGURE 6 FIGURE 13 PMID:8061184

  5. Order and disorder in irreversible decay processes.

    PubMed

    Nichols, Jonathan W; Flynn, Shane W; Green, Jason R

    2015-02-14

    Dynamical disorder motivates fluctuating rate coefficients in phenomenological, mass-action rate equations. The reaction order in these rate equations is the fixed exponent controlling the dependence of the rate on the number of species. Here, we clarify the relationship between these notions of (dis)order in irreversible decay, n A → B, n = 1, 2, 3, …, by extending a theoretical measure of fluctuations in the rate coefficient. The measure, Jn-Ln (2)≥0, is the magnitude of the inequality between Jn, the time-integrated square of the rate coefficient multiplied by the time interval of interest, and Ln (2), the square of the time-integrated rate coefficient. Applying the inequality to empirical models for non-exponential relaxation, we demonstrate that it quantifies the cumulative deviation in a rate coefficient from a constant, and so the degree of dynamical disorder. The equality is a bound satisfied by traditional kinetics where a single rate constant is sufficient. For these models, we show how increasing the reaction order can increase or decrease dynamical disorder and how, in either case, the inequality Jn-Ln (2)≥0 can indicate the ability to deduce the reaction order in dynamically disordered kinetics.

  6. Irreversible Electroporation for Colorectal Liver Metastases.

    PubMed

    Scheffer, Hester J; Melenhorst, Marleen C A M; Echenique, Ana M; Nielsen, Karin; van Tilborg, Aukje A J M; van den Bos, Willemien; Vroomen, Laurien G P H; van den Tol, Petrousjka M P; Meijerink, Martijn R

    2015-09-01

    Image-guided tumor ablation techniques have significantly broadened the treatment possibilities for primary and secondary hepatic malignancies. A new ablation technique, irreversible electroporation (IRE), was recently added to the treatment armamentarium. As opposed to thermal ablation, cell death with IRE is primarily induced using electrical energy: electrical pulses disrupt the cellular membrane integrity, resulting in cell death while sparing the extracellular matrix of sensitive structures such as the bile ducts, blood vessels, and bowel wall. The preservation of these structures makes IRE attractive for colorectal liver metastases (CRLM) that are unsuitable for resection and thermal ablation owing to their anatomical location. This review discusses different technical and practical issues of IRE for CRLM: the indications, patient preparations, procedural steps, and different "tricks of the trade" used to improve safety and efficacy of IRE. Imaging characteristics and early efficacy results are presented. Much is still unknown about the exact mechanism of cell death and about factors playing a crucial role in the extent of cell death. At this time, IRE for CRLM should only be reserved for small tumors that are truly unsuitable for resection or thermal ablation because of abutment of the portal triad or the venous pedicles.

  7. Irreversibility in a simple reversible model

    SciTech Connect

    Kumicak, Juraj

    2005-01-01

    This paper studies a parametrized family of familiar generalized Baker maps, viewed as simple models of time-reversible evolution. Mapping the unit square onto itself, the maps are partly contracting and partly expanding, but they preserve the global measure of the definition domain. They possess periodic orbits of any period, and all maps of the set have attractors with well defined structure. The explicit construction of the attractors is described and their structure is studied in detail. There is a precise sense in which one can speak about the absolute age of a state, regardless of whether the latter is applied to a single point, a set of points, or a distribution function. One can then view the whole trajectory as a set of past, present, and future states. This viewpoint is then applied to show that it is impossible to define a priori states with very large 'negative age'. Such states can be defined only a posteriori. This gives precise sense to irreversibility - or the 'arrow of time' - in these time-reversible maps, and is suggested as an explanation of the second law of thermodynamics also for some realistic physical systems.

  8. Irreversible Electroporation in a Swine Lung Model

    SciTech Connect

    Dupuy, Damian E.; Aswad, Bassam; Ng, Thomas

    2011-04-15

    Purpose: This study was designed to evaluate the safety and tissue effects of IRE in a swine lung model. Methods: This study was approved by the institutional animal care committee. Nine anesthetized domestic swine underwent 15 percutaneous irreversible electroporation (IRE) lesion creations (6 with bipolar and 3 with 3-4 monopolar electrodes) under fluoroscopic guidance and with pancuronium neuromuscular blockade and EKG gating. IRE electrodes were placed into the central and middle third of the right mid and lower lobes in all animals. Postprocedure PA and lateral chest radiographs were obtained to evaluate for pneumothorax. Three animals were sacrificed at 2 weeks and six at 4 weeks. Animals underwent high-resolution CT scanning and PA and lateral radiographs 1 h before sacrifice. The treated lungs were removed en bloc, perfused with formalin, and sectioned. Gross pathologic and microscopic changes after standard hematoxylin and eosin staining were analyzed within the areas of IRE lesion creation. Results: No significant adverse events were identified. CT showed focal areas of spiculated high density ranging in greatest diameter from 1.1-2.2 cm. On gross inspection of the sectioned lung, focal areas of tan discoloration and increased density were palpated in the areas of IRE. Histological analysis revealed focal areas of diffuse alveolar damage with fibrosis and inflammatory infiltration that respected the boundaries of the interlobular septae. No pathological difference could be discerned between the 2- and 4-week time points. The bronchioles and blood vessels within the areas of IRE were intact and did not show signs of tissue injury. Conclusion: IRE creates focal areas of diffuse alveolar damage without creating damage to the bronchioles or blood vessels. Short-term safety in a swine model appears to be satisfactory.

  9. An update on irreversible electroporation of liver tumours.

    PubMed

    Yeung, Enoch S L; Chung, Max W Y; Wong, Keedon; Wong, Clement Y K; So, Enoch C T; Chan, Albert C Y

    2014-08-01

    OBJECTIVE. To investigate the clinical efficacy and safety of irreversible electroporation for ablation of liver tumour in humans. DATA SOURCES. The PubMed and MEDLINE databases were systematically searched. STUDY SELECTION. Clinical research published in English in the last 10 years until October 2013 that address clinical issues related to irreversible electroporation of human liver tumours were selected. "Liver tumor", "local ablative therapy", and "irreversible electroporation" were used as the search terms. DATA EXTRACTION AND SYNTHESIS. The data extracted for this review was analysed by the authors, with a focus on the clinical efficacy and the safety of irreversible electroporation. The complete response rates look promising, ranging from 72% to 100%, except in one study in a subgroup of liver tumours in which the complete response rate was only 50% that was likely due to the inclusion of larger-size tumours. In one study, the local recurrence rate at 12 months was approximately 40%. As for the safety of irreversible electroporation, there were only a few reported complications (cardiac arrhythmia, pneumothorax, and electrolyte disturbance) that were mostly transient and not serious. There was no reported mortality related to the use of irreversible electroporation. CONCLUSION. Irreversible electroporation is a potentially effective liver tumour ablative therapy that gives rise to only mild and transient side-effects. Further studies with better patient selection criteria and longer follow-up are needed to clarify its role as a first-line liver tumour treatment modality.

  10. Pilot study of irreversible electroporation for intracranial surgery.

    PubMed

    Garcia, Paulo A; Rossmeisl, John H; Robertson, John; Ellis, Thomas L; Davalos, Rafael V

    2009-01-01

    Irreversible electroporation (IRE) is a new minimally invasive technique to treat cancer using intense but short electric pulses. This technique is unique because of its non-thermal mechanism of tissue ablation. Furthermore it can be predicted with numerical models and can be confirmed with ultrasound and MRI. We present some preliminary results on the safety of using irreversible electroporation for canine brain surgery. We also present the electric field (460 V/cm - 560 V/cm) necessary for focal ablation of canine brain tissue and provide some guidelines for treatment planning and execution. This preliminary study is the first step towards using irreversible electroporation as a brain cancer treatment. PMID:19964170

  11. Microscopic reversibility and macroscopic irreversibility: A lattice gas model

    NASA Astrophysics Data System (ADS)

    Pérez-Cárdenas, Fernando C.; Resca, Lorenzo; Pegg, Ian L.

    2016-09-01

    We present coarse-grained descriptions and computations of the time evolution of a lattice gas system of indistinguishable particles, whose microscopic laws of motion are exactly reversible, in order to investigate how or what kind of macroscopically irreversible behavior may eventually arise. With increasing coarse-graining and number of particles, relative fluctuations of entropy rapidly decrease and apparently irreversible behavior unfolds. Although that behavior becomes typical in those limits and within a certain range, it is never absolutely irreversible for any individual system with specific initial conditions. Irreversible behavior may arise in various ways. We illustrate one possibility by replacing detailed integer occupation numbers at lattice sites with particle probability densities that evolve diffusively.

  12. Dissipation and irreversibility for models of mechanochemical machines

    NASA Astrophysics Data System (ADS)

    Brown, Aidan; Sivak, David

    For biological systems to maintain order and achieve directed progress, they must overcome fluctuations so that reactions and processes proceed forwards more than they go in reverse. It is well known that some free energy dissipation is required to achieve irreversible forward progress, but the quantitative relationship between irreversibility and free energy dissipation is not well understood. Previous studies focused on either abstract calculations or detailed simulations that are difficult to generalize. We present results for mechanochemical models of molecular machines, exploring a range of model characteristics and behaviours. Our results describe how irreversibility and dissipation trade off in various situations, and how this trade-off can depend on details of the model. The irreversibility-dissipation trade-off points towards general principles of microscopic machine operation or process design. Our analysis identifies system parameters which can be controlled to bring performance to the Pareto frontier.

  13. Irreversibility of financial time series: A graph-theoretical approach

    NASA Astrophysics Data System (ADS)

    Flanagan, Ryan; Lacasa, Lucas

    2016-04-01

    The relation between time series irreversibility and entropy production has been recently investigated in thermodynamic systems operating away from equilibrium. In this work we explore this concept in the context of financial time series. We make use of visibility algorithms to quantify, in graph-theoretical terms, time irreversibility of 35 financial indices evolving over the period 1998-2012. We show that this metric is complementary to standard measures based on volatility and exploit it to both classify periods of financial stress and to rank companies accordingly. We then validate this approach by finding that a projection in principal components space of financial years, based on time irreversibility features, clusters together periods of financial stress from stable periods. Relations between irreversibility, efficiency and predictability are briefly discussed.

  14. Extended irreversible thermodynamics and the quality of temperature and pressure

    NASA Astrophysics Data System (ADS)

    Bhalekar, Anil A.

    1999-08-01

    It is reiterated that without a Gibbs-Duhem equation no thermodynamic description ofirreversible and reversible processes exists. It is shown with the help of Gibbs-Duhem equation of extended irreversible thermodynamics that the physical contents of intensive quantities, the temperature and the pressure, do not change in going from reversible to irreversible processes. This confirms well with the earlier demonstrations of Eu and Garcia-Colin.

  15. Anisotropic shift of the irreversibility line by neutron irradiation

    SciTech Connect

    Sauerzopf, F.M.; Wiesinger, H.P.; Weber, H.W. ); Crabtree, G.W.; Frischherz, M.C.; Kirk, M.A. )

    1991-09-01

    The irreversibility line of high-{Tc} superconductors is shifted considerably by irradiating the material with fast neutrons. The anisotropic and non-monotonous shift is qualitatively explained by a simple model based on an interaction between three pinning mechanisms, the intrinsic pinning by the ab-planes, the weak pinning by the pre-irradiation defect structure, and strong pinning by neutron induced defect cascades. A correlation between the cascade density and the position of the irreversibility line is observed.

  16. Irreversible pulpitis and achieving profound anesthesia: Complexities and managements

    PubMed Central

    Modaresi, Jalil; Davoudi, Amin; Badrian, Hamid; Sabzian, Roya

    2016-01-01

    Dental pain management is one of the most critical aspects of modern dentistry. Irreversible pulpitis and further root canal therapy might cause an untolerated pain to the patients. The improvements in anesthetic agents and techniques were one of the advantages of studying nerve biology and stimulation. This article tried to overview of the nerve activities in inflammatory environments or induced pain. Furthermore, the proper advises, and supplementary techniques were reviewed for better pain management of irreversible pulpitis. PMID:26957681

  17. Attribution of irreversible loss to anthropogenic climate change

    NASA Astrophysics Data System (ADS)

    Huggel, Christian; Bresch, David; Hansen, Gerrit; James, Rachel; Mechler, Reinhard; Stone, Dáithí; Wallimann-Helmer, Ivo

    2016-04-01

    The Paris Agreement (2015) under the UNFCCC has anchored loss and damage in a separate article which specifies that understanding and support should be enhanced in areas addressing loss and damage such as early warning, preparedness, insurance and resilience. Irreversible loss is a special category under loss and damage but there is still missing clarity over what irreversible loss actually includes. Many negative impacts of climate change may be handled or mitigated by existing risk management, reduction and absorption approaches. Irreversible loss, however, is thought to be insufficiently addressed by risk management. Therefore, countries potentially or actually affected by irreversible loss are calling for other measures such as compensation, which however is highly contested in international climate policy. In Paris (2015) a decision was adopted that loss and damage as defined in the respective article of the agreement does not involve compensation and liability. Nevertheless, it is likely that some sort of mechanism will eventually need to come into play for irreversible loss due to anthropogenic climate change, which might involve compensation, other forms of non-monetary reparation, or transformation. Furthermore, climate litigation has increasingly been attempted to address negative effects of climate change. In this context, attribution is important to understand the drivers of change, what counts as irreversible loss due to climate change, and, possibly, who or what is responsible. Here we approach this issue by applying a detection and attribution perspective on irreversible loss. We first analyze detected climate change impacts as assessed in the IPCC Fifth Assessment Report. We distinguish between irreversible loss in physical, biological and human systems, and accordingly identify the following candidates of irreversible loss in these systems: loss of glaciers and ice sheets, loss of subsurface ice (permafrost) and related loss of lake systems; loss

  18. Partially-irreversible sorption of formaldehyde in five polymers

    NASA Astrophysics Data System (ADS)

    Ye, Wei; Cox, Steven S.; Zhao, Xiaomin; Frazier, Charles E.; Little, John C.

    2014-12-01

    Due to its environmental ubiquity and concern over its potential toxicity, the mass-transfer characteristics of formaldehyde are of critical importance to indoor air quality research. Previous studies have suggested that formaldehyde mass transfer in polymer is partially irreversible. In this study, mechanisms that could cause the observed irreversibility were investigated. Polycarbonate and four other polymeric matrices were selected and subjected to formaldehyde sorption/desorption cycles. Mass transfer of formaldehyde was partially irreversible in all cases, and three potential mechanisms were evaluated. First, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis was used to investigate possible formaldehyde polymerization on polymer surfaces. ATR-FTIR showed no detectable paraformaldehyde or formaldehyde on the film surfaces that had been exposed to formaldehyde and air. ATR-FTIR did detect aliphatic acids suggesting oxidation had occurred on film surfaces as a result of exposure to formaldehyde. However, additional study suggested that air is not the primary cause for irreversibility. Second, statistical physics theory was tested as a possible explanation. According to this theory, reversible and irreversible sorption could be taking place simultaneously. The irreversible fraction should be constant during sorption and the fraction could be determined by performing a complete sorption/desorption test. The sorption/desorption data was consistent with this theory. Third, chemisorption was considered as another possible cause for irreversibility. Extraction/fluorimetry testing of post-sorption and post-desorption polymer films showed measurable quantities of formaldehyde suggesting that some of the chemisorbed formaldehyde was reversible at the higher extraction temperature. Further quantitative study on chemical reaction products is needed.

  19. Irreversible climate change due to carbon dioxide emissions.

    PubMed

    Solomon, Susan; Plattner, Gian-Kasper; Knutti, Reto; Friedlingstein, Pierre

    2009-02-10

    The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450-600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the "dust bowl" era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4-1.0 m if 21st century CO(2) concentrations exceed 600 ppmv and 0.6-1.9 m for peak CO(2) concentrations exceeding approximately 1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer.

  20. Irreversible climate change due to carbon dioxide emissions.

    PubMed

    Solomon, Susan; Plattner, Gian-Kasper; Knutti, Reto; Friedlingstein, Pierre

    2009-02-10

    The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450-600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the "dust bowl" era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4-1.0 m if 21st century CO(2) concentrations exceed 600 ppmv and 0.6-1.9 m for peak CO(2) concentrations exceeding approximately 1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer. PMID:19179281

  1. Spectral line intensity irreversibility in circulatory plasma magnetization processes

    SciTech Connect

    Qu, Z. Q.; Dun, G. T.

    2012-01-23

    Spectral line intensity variation is found to be irreversible in circulatory plasma magnetization process by experiments described in this paper, i.e., the curves illustrating spectral line photon fluxes irradiated from a light source immerged in a magnetic field by increasing the magnetic induction cannot be reproduced by decreasing the magnetic induction within the errors. There are two plasma magnetization patterns found. One shows that the intensities are greater at the same magnetic inductions during the magnetic induction decreasing process after the increasing, and the other gives the opposite effect. This reveals that the magneto-induced excitation and de-excitation process is irreversible like ferromagnetic magnetization. But the two irreversible processes are very different in many aspects stated in the text.

  2. Irreversible aggregation of flexible chainlike walkers without adherence.

    PubMed

    Mashiko, Takashi

    2008-07-01

    The flexible chainlike walker (FCW) model is proposed as a minimal model of a deformable moving object and as an extension of the regular random-walk model. The many-body system of FCWs is studied by numerical simulations on a square lattice. It is shown that FCWs aggregate spontaneously and irreversibly where no adherence is assumed, in contrast to the established aggregation models, where adherence is indispensable for their occurrence and irreversibility. This type of aggregation is enabled by and demonstrates the significance of the deformability of moving objects.

  3. Entanglement irreversibility from quantum discord and quantum deficit.

    PubMed

    Cornelio, Marcio F; de Oliveira, Marcos C; Fanchini, Felipe F

    2011-07-01

    We relate the problem of irreversibility of entanglement with the recently defined measures of quantum correlation--quantum discord and one-way quantum deficit. We show that the entanglement of formation is always strictly larger than the coherent information and the entanglement cost is also larger in most cases. We prove irreversibility of entanglement under local operations and classical communication for a family of entangled states. This family is a generalization of the maximally correlated states for which we also give an analytic expression for the distillable entanglement, the relative entropy of entanglement, the distillable secret key, and the quantum discord.

  4. First Law of Thermodynamics; Irreversible and Reversible Processes

    NASA Astrophysics Data System (ADS)

    Craig, Norman C.; Gislason, Eric A.

    2002-02-01

    The experimental basis for the first law of thermodynamics and related operational definitions are reviewed. An alternative, adiabatic-work formulation of the first law is evaluated. New mathematical expressions for irreversible work in isothermal and adiabatic expansions and compressions of an ideal gas are presented. The work for these irreversible processes is compared graphically with the reversible limit. For the adiabatic case some numerical explorations are also done. An operational definition for reversible processes in purely first-law terms is presented and applied.

  5. A new method for making casts from irreversible hydrocolloid impressions.

    PubMed

    Steas, A

    1991-03-01

    This method of making casts from alginate (irreversible hydrocolloid) edentulous impressions is a departure from the usual procedures. It consists of recognizing the weaknesses of the materials being used and handling them to the best advantage to minimize deleterious effects. A proper dental stone mixed with an accelerator is painted over the entire anatomic surface of the impression. A base is added only after the first application of stone sets. This method protects against volume change of the irreversible hydrocolloid impression material and distortion of the unsupported portions of the impression.

  6. The Irreversible Process of University "Democratization": The Danish Case.

    ERIC Educational Resources Information Center

    Pedersen, Mogens N.

    1988-01-01

    The Danish experience with university democratization suggests that the process is irreversible and that its progress is determined by how the initial change was begun two decades ago. It is also proposed that government attempts to intervene and revoke traditional institutional autonomy threaten to invalidate the progress made. (Author/MSE)

  7. When an Adiabatic Irreversible Expansion or Compression Becomes Reversible

    ERIC Educational Resources Information Center

    Anacleto, Joaquim; Ferreira, J. M.; Soares, A. A.

    2009-01-01

    This paper aims to contribute to a better understanding of the concepts of a "reversible process" and "entropy". For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure P[subscript i] to a final pressure P[subscript f], by being placed in…

  8. Pressure-Volume Integral Expressions for Work in Irreversible Processes

    ERIC Educational Resources Information Center

    Gislason, Eric A.; Craig, Norman C.

    2007-01-01

    Different formulations of thermodynamic work "w" as a pressure-volume integral are examined for a piston moving against a gas in an irreversible process. Proper expressions are obtained using the instantaneous pressure of the gas on the piston as the integrand and also using certain external pressures as the integrand. There are two common yet…

  9. BNNT-mediated irreversible electroporatio: its potential on cancer cells

    SciTech Connect

    Vittoria Raffa, Cristina Riggio, Michael W. Smith, Kevin C. Jordan, Wei Cao, Alfred Cuschieri

    2012-10-01

    Tissue ablation, i.e., the destruction of undesirable tissues, has become an important minimally invasive technique alternative to resection surgery for the treatment of tumours. Several methods for tissue ablation are based on thermal techniques using cold, e.g. cryosurgery [1] or heat, e.g. radiofrequency [2] or high-intensity focused ultrasound [3] or nanoparticle-mediated irradiation [4]. Alternatively, irreversible electroporation (IRE) has been proposed as non thermal technique for minimally invasive tissue ablation based on the use of electrical pulses. When the electric field is applied to a cell, a change in transmembrane potential is induced, which can cause biochemical and physiological changes of the cell. When the threshold value of the transmembrane potential is exceeded, the cell membrane becomes permeable, thus allowing entrance of molecules that otherwise cannot cross the membrane [5]. A further increase in the electric field intensity may cause irreversible membrane permeabilization and cell death. These pulses create irreversible defects (pores) in the cell membrane lipid bilayer, causing cell death through loss of cell homeostasis [6]. This is desirable in tumour ablation in order to produce large cell death, without the use of cytostatic drugs. A study of Davalos, Mir and Rubinsky showed that IRE can ablate substantial volumes of tissue without inducing a thermal effect and therefore serve as an independent and new tissue ablation modality; this opened the way to the use of IRE in surgery [7]. Their finding was subsequently confirmed in studies on cells [8], small animal models [9] and in large animal models in the liver [10] and the heart [11]. The most important finding in these papers is that irreversible electroporation produces precisely delineated ablation zones with cell scale resolution between ablated and non-ablated areas, without zones in which the extent of damage changes gradually as during thermal ablation. Furthermore, it is

  10. Aftereffect in rocks caused by preexisting irreversible deformations

    SciTech Connect

    Stavrogin, A.N.; Shirkes, O.A.

    1987-05-01

    In this paper, rock specimens cut as cores of a diameter of 30 mm, 80 mm in length, were subjected to irreversible deformation in a high hydrostatic pressure chamber according to Karman's procedure. The types of rocks investigated were white Koelga marble, non-burst-hazardous (NBH) sandstone from Donets Basin, limestone from Estonslanets deposit and brown coal from Shurab coal deposit. Marble specimens were subjected to the most extensive studies. The aftereffect curves are shown for each type of rock studied. Aftereffect deformations of rocks are basically creep flows occurring under the effect of residual stresses introduced into the rock material on the course of its irreversible deformation by a high hydrostatic pressure, according to the authors. The physical nature of the residual stresses in the rocks and the mechanism of their creation are examined at the level of structural elements (grains or crystals).

  11. Flux pinning characteristics and irreversibility line in high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Matsushita, T.; Ihara, N.; Kiuchi, M.

    1995-01-01

    The flux pinning properties in high temperature superconductors are strongly influenced by thermally activated flux motion. The scaling relation of the pinning force density and the irreversibility line in various high temperature superconductors are numerically analyzed in terms of the flux creep model. The effect of two factors, i.e., the flux pinning strength and the dimensionality of the material, on these properties are investigated. It is speculated that the irreversibility line in Bi-2212 superconductors is one order of magnitude smaller than that in Y-123, even if the flux pinning strength in Bi-2212 is improved up to the level of Y-123. It is concluded that these two factors are equally important in determination of the flux pinning characteristics at high temperatures.

  12. Flux pinning characteristics and irreversibility line in high temperature superconductors

    SciTech Connect

    Matsushita, T.; Ihara, N.; Kiuchi, M.

    1995-04-01

    The flux pinning properties in high temperature superconductors are strongly influenced by thermally activated flux motion. The scaling relation of the pinning force density and the irreversibility line in various high temperature superconductors are numerically analyzed in terms of the flux creep model. The effect of two factors, i.e., the flux pinning strength and the dimensionality of the material, on these properties are investigated. It is speculated that the irreversibility line in Bi-2212 superconductors is one order of magnitude smaller than that in Y-123, even if the flux pinning strength in Bi-2212 is improved up to the level of Y-123. It is concluded that these two factors are equally important in determination of the flux pinning characteristics at high temperatures.

  13. Prostaglandin E2 to diagnose between reversible and irreversible pulpitis.

    PubMed

    Petrini, M; Ferrante, M; Ciavarelli, L; Brunetti, L; Vacca, M; Spoto, G

    2012-01-01

    The aim of this work is to verify a correlation between the grade of inflammation and the concentration of PGE2 in human dental pulp. A total of 25 human dental pulps were examined by histological analysis and radioimmunologic dosage of PGE2. The pulps used in this experiment were from healthy and symptomatic teeth; the first ones were collected from teeth destined to be extracted for orthodontic reasons. An increase was observed of PGE2 in reversible pulpitis compared with healthy pulps and with the irreversible pulpitis and the clear decrease of these when NSAIDs are taken. This study demonstrates that PGE2 level is correlated to histological analysis thus allowing to distinguish symptomatic teeth in reversible and irreversible pulpitis. PMID:22507328

  14. Irreversible adsorption of phenolic compounds by activated carbons

    SciTech Connect

    Grant, T.M.; King, C.J.

    1988-12-01

    Studies were undertaken to determine the reasons why phenolic sorbates can be difficult to remove and recover from activated carbons. The chemical properties of the sorbate and the adsorbent surface, and the influences of changes in the adsorption and desorption conditions were investigated. Comparison of isotherms established after different contact times or at different temperatures indicated that phenolic compounds react on carbon surfaces. The reaction rate is a strong function of temperature. Regeneration of carbons by leaching with acetone recovered at least as much phenol as did regeneration with other solvents or with displacers. The physiochemical properties of adsorbents influences irreversible uptakes. Sorbates differed markedly in their tendencies to undergo irreversible adsorption. 64 refs., 47 figs., 32 tabs.

  15. Peroxidatic degradation of azide by catalase and irreversible enzyme inactivation.

    PubMed

    Lardinois, O M; Rouxhet, P G

    1996-12-01

    A study of the azide reaction with bovine liver catalase in presence of hydrogen peroxide has been performed, using conventional UV-visible spectrometry and activity measurements. Compound III and NO-ferrocatalase were the predominant forms of the enzyme observed in air and under nitrogen, respectively. A reaction scheme for peroxidatic degradation of azide by catalase is proposed. Accordingly, accumulation of Compound III is the main factor responsible for the reversible inhibition of 'catalatic' activity by azide, while formation of a complex between native catalase and azide has a negligible effect. Catalase is irreversibly inactivated by prolonged exposure to high levels of H2O2 and azide. The latter involves cleavage of the prosthetic group with liberation of the heme iron. Both in air and under nitrogen, generation of azidyl radicals seems to play a minor role in the irreversible inactivation process. PMID:8980644

  16. A Comparison of Reversible Versus Irreversible Protein Glutathionylation

    PubMed Central

    Townsend, Danyelle M.; Lushchak, Volodymyr I.; Cooper, Arthur J.L.

    2015-01-01

    Glutathionylation is generally a reversible posttranslational modification that occurs to cysteine residues that have been exposed to reactive oxygen species (P-SSG). This cyclical process can regulate various clusters of proteins, including those involved in critical cellular signaling functions. However, certain conditions can favor the formation of dehydroamino acids, such as 2,3-didehydroalanine (2,3-dehydroalanine, DHA) and 2,3-didehydrobutyrine (2,3-dehydrobutyrine), which can act as Michael acceptors. In turn, these can form Michael adducts with glutathione (GSH), resulting in the formation of a stable thioether conjugate, an irreversible process referred to as nonreducible glutathionylation. This is predicted to be prevalent in nature, particularly in more slowly turning over proteins. Such nonreducible glutathionylation can be distinguished from the more facile cycling signaling processes and is predicted to be of gerontological, toxicological, pharmacological, and oncological relevance. Here, we compare reversible and irreversible glutathionylation. PMID:24974182

  17. Thermoeconomic analysis of an irreversible Stirling heat pump cycle

    NASA Astrophysics Data System (ADS)

    Lucia, U.; Gervino, G.

    2006-03-01

    In this paper an analysis of the Stirling cycle in thermoeconomic terms is developed using the entropy generation. In the thermoeconomic optimization of an irreversible Stirling heat pump cycle the F function has been introduced to evaluate the optimum for the higher and lower sources temperature ratio in the cycle: this ratio represents the value which optimizes the cycle itself. The variation of the function F is proportional to the variation of the entropy generation, the maxima and minima of F has been evaluated in a previous paper without giving the physical foundation of the method. We investigate the groundwork of this approach: to study the upper and lower limits of F function allows to determine the cycle stability and the optimization conditions. The optimization consists in the best COP at the least cost. The principle of maximum variation for the entropy generation becomes the analytic foundation of the optimization method in the thermoeconomic analysis for an irreversible Stirling heat pump cycle.

  18. Variability of Irreversible Poleward Transport in the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Olsen, Mark; Douglass, Anne; Newman, Paul; Nash, Eric; Witte, Jacquelyn; Ziemke, Jerry

    2011-01-01

    The ascent and descent of the Brewer-Dobson circulation plays a large role in determining the distributions of many constituents in the extratropical lower stratosphere. However, relatively fast, quasi-horizontal transport out of the tropics and polar regions also significantly contribute to determining these distributions. The tropical tape recorder signal assures that there must be outflow from the tropics into the extratropical lower stratosphere. The phase of the quasi-biennial oscillation (QBO) and state of the polar vortex are known to modulate the transport from the tropical and polar regions, respectively. In this study we examine multiple years of ozone distributions in the extratropical lower stratosphere observed by the Aura Microwave Limb Sounder (MLS) and the Aura High Resolution Dynamic Limb Sounder (HIRDLS). The distributions are compared with analyses of irreversible, meridional isentropic transport. We show that there is considerable year-to-year seasonal variability in the amount of irreversible transport from the tropics, which is related to both the phase of the QBO and the state of the polar vortex. The reversibility of the transport is consistent with the number of observed breaking waves. The variability of the atmospheric index of refraction in the lower stratosphere is shown to be significantly correlated with the wave breaking and amount of irreversible transport. Finally, we will show that the seasonal extratropical stratosphere to troposphere transport of ozone can be substantially modulated by the amount of irreversible meridional transport in the lower stratosphere and we investigate how observable these differences are in data of tropospheric ozone.

  19. Irreversibility and chaos: role of lubrication interactions in sheared suspensions.

    PubMed

    Metzger, Bloen; Pham, Phong; Butler, Jason E

    2013-05-01

    We investigate non-Brownian particles suspended in a periodic shear-flow using simulations. Following Metzger and Butler [Phys. Rev. E 82, 051406 (2010)], we show that the chaotic dynamics arising from lubrication interactions are too weak to generate an observable particle dispersion. The irreversibility observed in periodic flow is dominated by contact interactions. Nonetheless, we show that lubrication interactions must be included in the calculation to obtain results that agree with experiments.

  20. Thermodynamical estimation of the limit potentialities of irreversible binary distillation

    NASA Astrophysics Data System (ADS)

    Tsirlin, A. M.; Grigorevsky, I. N.

    2010-10-01

    The limit capacity of binary distillation is considered for conventional heat supply to the column bottom and heat removal from the refluxer and for heat supply and removal distributed over the column height. The form of operating line, appropriating to the minimum of irreversible loss for adjusted productivity and limited transfer coefficients, was found. The expression for possible capacity limit of the distillation column was obtained, depending on flow composition and heat and mass transfer coefficients.

  1. Irreversibility and complex network behavior of stream flow fluctuations

    NASA Astrophysics Data System (ADS)

    Serinaldi, Francesco; Kilsby, Chris G.

    2016-05-01

    Exploiting the duality between time series and networks, directed horizontal visibility graphs (DHVGs) are used to perform an unprecedented analysis of the dynamics of stream flow fluctuations with focus on time irreversibility and long range dependence. The analysis relies on a large quality-controlled data set consisting of 699 daily time series recorded in the continental United States (CONUS) that are not affected by human activity and primarily reflects meteorological conditions. DHVGs allow a clear visualization and quantification of time irreversibility of flow dynamics, which can be interpreted as a signature of nonlinearity, and long range dependence resulting from the interaction of atmospheric, surface and underground processes acting at multiple spatio-temporal scales. Irreversibility is explored by mapping the time series into ingoing, outgoing, and undirected graphs and comparing the corresponding degree distributions. Using surrogate data preserving up to the second order linear temporal dependence properties of the observed series, DHVGs highlight the additional complexity introduced by nonlinearity into flow fluctuation dynamics. We show that the degree distributions do not decay exponentially as expected, but tend to follow a subexponential behavior, even though sampling uncertainty does not allow a clear distinction between apparent or true power law decay. These results confirm that the complexity of stream flow dynamics goes beyond a linear representation involving for instance the combination of linear processes with short and long range dependence, and requires modeling strategies accounting for temporal asymmetry and nonlinearity.

  2. Anesthetic Efficacy in Irreversible Pulpitis: A Randomized Clinical Trial.

    PubMed

    Allegretti, Carlos E; Sampaio, Roberta M; Horliana, Anna C R T; Armonia, Paschoal L; Rocha, Rodney G; Tortamano, Isabel Peixoto

    2016-01-01

    Inferior alveolar nerve block has a high failure rate in the treatment of mandibular posterior teeth with irreversible pulpitis. The aim of this study was to compare the anesthetic efficacy of 4% articaine, 2% lidocaine and 2% mepivacaine, all in combination with 1:100,000 epinephrine, in patients with irreversible pulpitis of permanent mandibular molars during a pulpectomy procedure. Sixty-six volunteers from the Emergency Center of the School of Dentistry, University of São Paulo, randomly received 3.6 mL of local anesthetic as a conventional inferior alveolar nerve block (IANB). The subjective signal of lip numbness, pulpal anesthesia and absence of pain during the pulpectomy procedure were evaluated respectively, by questioning the patient, stimulation using an electric pulp tester and a verbal analogue scale. All patients reported the subjective signal of lip numbness. Regarding pulpal anesthesia success as measured with the pulp tester, the success rate was respectively 68.2% for mepivacaine, 63.6% for articaine and 63.6% for lidocaine. Regarding patients who reported no pain or mild pain during the pulpectomy, the success rate was, respectively 72.7% for mepivacaine, 63.6% for articaine and 54.5% for lidocaine. These differences were not statistically significant. Neither of the solutions resulted in 100% anesthetic success in patients with irreversible pulpitis of mandibular molars.

  3. Irreversible steps in the ferritin synthesis induction pathway.

    PubMed

    Goessling, L S; Mascotti, D P; Bhattacharyya-Pakrasi, M; Gang, H; Thach, R E

    1994-02-11

    The ability of cells to re-repress ferritin synthesis after removal of an inducing agent (iron or heme) was investigated. Re-repression was found to be a slow process, requiring approximately 4 (after iron removal) to 10 h (after heme removal) for completion. Desferrioxamine mesylate (Desferal) had only a slight effect on the rate of re-repression, whereas cycloheximide was strongly inhibitory, indicating that new protein synthesis is required for re-repression. Re-repression occurred at a slow but significant rate in the presence of both Desferal and cycloheximide. These results indicate that, in the absence of an iron chelator, the induction of ferritin synthesis is essentially irreversible. The kinetics of the previously reported covalent modification of IRE-binding protein (IRE-BP) were then examined, to see whether this phenomenon might account (at least in part) for the irreversibility of induction. It was found that the heme- or iron-dependent disappearance of 98-kDa IRE-BP occurred rapidly (within 1 h), and was equally rapidly reversed upon removal of heme after a 1-h exposure. By contrast, after a 4-h exposure to heme, little 98-kDa IRE-BP could be regenerated after heme removal. These results suggest that the slow, irreversible covalent modification of IRE-BP correlates closely over time with the induction of ferritin synthesis. The covalent modification of IRE-BP depends on cell growth rate, and is most readily detected in rapidly growing cells.

  4. Developing irreversible inhibitors of the protein kinase cysteinome

    PubMed Central

    Liu, Qingsong; Sabnis, Yogesh; Zhao, Zheng; Zhang, Tinghu; Buhrlage, Sara J.; Jones, Lyn H.; Gray, Nathanael S.

    2013-01-01

    Protein kinases are a large family of approximately 530 highly conserved enzymes that transfer a γ-phosphate group from ATP to a variety of amino acid residues such as tyrosine, serine and threonine which serves as a ubiquitous mechanism for cellular signal transduction. The clinical success of a number of kinase-directed drugs and the frequent observation of disease causing mutations in protein kinases suggest that a large number of kinases may represent therapeutically relevant targets. To-date the majority of clinical and preclinical kinase inhibitors are ATP-competitive, non-covalent inhibitors that achieve selectivity through recognition of unique features of particular protein kinases. Recently there has been renewed interest in the development of irreversible inhibitors that form covalent bonds with cysteine or other nucleophilic residues in the ATP-binding pocket. Irreversible kinase inhibitors have a number of potential advantages including prolonged pharmacodynamics, suitability for rational design, high potency and ability to validate pharmacological specificity through mutation of the reactive cysteine residue. Here we review recent efforts to develop cysteine-targeted irreversible protein kinase inhibitors and discuss their modes of recognizing the ATP-binding pocket and their biological activity profiles. In addition, we provided an informatics assessment of the potential ‘kinase-cysteinome’ and discuss strategies for the efficient development of new covalent inhibitors. PMID:23438744

  5. Irreversible Electroporation for Focal Ablation at the Porta Hepatis

    SciTech Connect

    Kasivisvanathan, Veeru; Thapar, Ankur Oskrochi, Youssof; Picard, John; Leen, Edward L. S.

    2012-12-15

    Patients with chemotherapy-refractory liver metastases who are not candidates for surgery may be treated with focal ablation techniques with established survival benefits. Irreversible electroporation is the newest of these and has the putative advantages of a nonthermal action, preventing damage to adjacent biliary structures and bowel. This report describes the use of irreversible electroporation in a 61-year-old man with a solitary chemoresistant liver metastasis unsuitable for radiofrequency ablation as a result of its proximity to the porta hepatis. At 3 months, tumor size was decreased on computed tomography from 28 Multiplication-Sign 19 to 20 Multiplication-Sign 17 mm, representing stable disease according to the response evaluation criteria in solid tumors. This corresponded to a decrease in tumor volume size from 5.25 to 3.16 cm{sup 3}. There were no early or late complications. Chemoresistant liver metastases in the proximity of the porta hepatis that are considered to be too high a risk for conventional surgery or thermal ablation may be considered for treatment by the novel ablation technique of irreversible electroporation.

  6. Typical pure nonequilibrium steady states and irreversibility for quantum transport.

    PubMed

    Monnai, Takaaki; Yuasa, Kazuya

    2016-07-01

    It is known that each single typical pure state in an energy shell of a large isolated quantum system well represents a thermal equilibrium state of the system. We show that such typicality holds also for nonequilibrium steady states (NESS's). We consider a small quantum system coupled to multiple infinite reservoirs. In the long run, the total system reaches a unique NESS. We identify a large Hilbert space from which pure states of the system are to be sampled randomly and show that the typical pure states well describe the NESS. We also point out that the irreversible relaxation to the unique NESS is important to the typicality of the pure NESS's.

  7. Typical pure nonequilibrium steady states and irreversibility for quantum transport

    NASA Astrophysics Data System (ADS)

    Monnai, Takaaki; Yuasa, Kazuya

    2016-07-01

    It is known that each single typical pure state in an energy shell of a large isolated quantum system well represents a thermal equilibrium state of the system. We show that such typicality holds also for nonequilibrium steady states (NESS's). We consider a small quantum system coupled to multiple infinite reservoirs. In the long run, the total system reaches a unique NESS. We identify a large Hilbert space from which pure states of the system are to be sampled randomly and show that the typical pure states well describe the NESS. We also point out that the irreversible relaxation to the unique NESS is important to the typicality of the pure NESS's.

  8. Discovery of a selective irreversible BMX inhibitor for prostate cancer.

    PubMed

    Liu, Feiyang; Zhang, Xin; Weisberg, Ellen; Chen, Sen; Hur, Wooyoung; Wu, Hong; Zhao, Zheng; Wang, Wenchao; Mao, Mao; Cai, Changmeng; Simon, Nicholas I; Sanda, Takaomi; Wang, Jinhua; Look, A Thomas; Griffin, James D; Balk, Steven P; Liu, Qingsong; Gray, Nathanael S

    2013-07-19

    BMX is a member of the TEC family of nonreceptor tyrosine kinases. We have used structure-based drug design in conjunction with kinome profiling to develop a potent, selective, and irreversible BMX kinase inhibitor, BMX-IN-1, which covalently modifies Cys496. BMX-IN-1 inhibits the proliferation of Tel-BMX-transformed Ba/F3 cells at two digit nanomolar concentrations but requires single digit micromolar concentrations to inhibit the proliferation of prostate cancer cell lines. Using a combinatorial kinase inhibitor screening strategy, we discovered that the allosteric Akt inhibitor, MK2206, is able to potentiate BMX inhibitor's antiproliferation efficacy against prostate cancer cells. PMID:23594111

  9. Expedited Record Base Fabrication Using an Irreversible Hydrocolloid Cast.

    PubMed

    Oh, Won-suk; Park, Ju-mi

    2016-04-01

    The registration of a maxillomandibular relationship requires additional clinical and laboratory procedures when the mouth presents with loss of occlusal support. This procedure can be a challenge for a patient who needs urgent care or resides in a remote area. This article describes a procedure for expediting the mounting of a master cast for the fabrication of a maxillary immediate complete denture. The technique presented describes the use of a silicone record base made on an irreversible hydrocolloid cast generated from the final impression.

  10. Intrinsic irreversibility limits the efficiency of multidimensional molecular motors.

    PubMed

    Jack, M W; Tumlin, C

    2016-05-01

    We consider the efficiency limits of Brownian motors able to extract work from the temperature difference between reservoirs or from external thermodynamic forces. These systems can operate in a variety of modes, including as isothermal engines, heat engines, refrigerators, and heat pumps. We derive analytical results showing that certain classes of multidimensional Brownian motor, including the Smoluchowski-Feynman ratchet, are unable to attain perfect efficiency (Carnot efficiency for heat engines). This demonstrates the presence of intrinsic irreversibilities in their operating mechanism. We present numerical simulations showing that in some cases the loss process that limits efficiency is associated with vortices in the probability current.

  11. Microscopic time-reversibility and macroscopic irreversibility: Still a paradox

    SciTech Connect

    Posch, H.A.; Dellago, Ch.; Hoover, W.G.; Kum, O. |

    1995-09-13

    Microscopic time reversibility and macroscopic irreversibility are a paradoxical combination. This was first observed by J. Loschmidt in 1876 and was explained, for conservative systems, by L. Boltzmann the following year. Both these features are also present in modern simulations of classic many-body systems in steady nonequilibrium states. We illustrate them here for the simplest possible models, a continuous one-dimensional model of field-driven diffusion, the so-called driven Lorentz gas or Galton Board, and an ergodic time reversible dissipative map.

  12. Intrinsic irreversibility limits the efficiency of multidimensional molecular motors

    NASA Astrophysics Data System (ADS)

    Jack, M. W.; Tumlin, C.

    2016-05-01

    We consider the efficiency limits of Brownian motors able to extract work from the temperature difference between reservoirs or from external thermodynamic forces. These systems can operate in a variety of modes, including as isothermal engines, heat engines, refrigerators, and heat pumps. We derive analytical results showing that certain classes of multidimensional Brownian motor, including the Smoluchowski-Feynman ratchet, are unable to attain perfect efficiency (Carnot efficiency for heat engines). This demonstrates the presence of intrinsic irreversibilities in their operating mechanism. We present numerical simulations showing that in some cases the loss process that limits efficiency is associated with vortices in the probability current.

  13. Intrinsic irreversibility limits the efficiency of multidimensional molecular motors.

    PubMed

    Jack, M W; Tumlin, C

    2016-05-01

    We consider the efficiency limits of Brownian motors able to extract work from the temperature difference between reservoirs or from external thermodynamic forces. These systems can operate in a variety of modes, including as isothermal engines, heat engines, refrigerators, and heat pumps. We derive analytical results showing that certain classes of multidimensional Brownian motor, including the Smoluchowski-Feynman ratchet, are unable to attain perfect efficiency (Carnot efficiency for heat engines). This demonstrates the presence of intrinsic irreversibilities in their operating mechanism. We present numerical simulations showing that in some cases the loss process that limits efficiency is associated with vortices in the probability current. PMID:27300832

  14. Quantum Chaos, Irreversible Classical Dynamics, and Random Matrix Theory

    NASA Astrophysics Data System (ADS)

    Andreev, A. V.; Agam, O.; Simons, B. D.; Altshuler, B. L.

    1996-05-01

    The Bohigas-Giannoni-Schmit conjecture stating that the statistical spectral properties of systems which are chaotic in their classical limit coincide with random matrix theory (RMT) is proved. A new semiclassical field theory for individual chaotic systems is constructed in the framework of a nonlinear σ model. The low lying modes are shown to be associated with the Perron-Frobenius (PF) spectrum of the underlying irreversible classical dynamics. It is shown that the existence of a gap in the PF spectrum results in RMT behavior. Moreover, our formalism offers a way of calculating system specific corrections beyond RMT.

  15. Carnot's cycle for small systems: Irreversibility and cost of operations

    NASA Astrophysics Data System (ADS)

    Sekimoto, Ken; Takagi, Fumiko; Hondou, Tsuyoshi

    2000-12-01

    In the thermodynamic limit, the existence of a maximal efficiency of energy conversion attainable by a Carnot cycle consisting of quasistatic isothermal and adiabatic processes precludes the existence of a perpetual machine of the second kind, whose cycles yield positive work in an isothermal environment. We employ the recently developed framework of the energetics of stochastic processes (called ``stochastic energetics'') to reanalyze the Carnot cycle in detail, taking account of fluctuations, without taking the thermodynamic limit. We find that in this nonmacroscopic situation both processes of connection to and disconnection from heat baths and adiabatic processes that cause distortion of the energy distribution are sources of inevitable irreversibility within the cycle. Also, the so-called null-recurrence property of the cumulative efficiency of energy conversion over many cycles and the irreversible property of isolated, purely mechanical processes under external ``macroscopic'' operations are discussed in relation to the impossibility of a perpetual machine, or Maxwell's demon. This analysis may serve as the basis for the design and analysis of mesoscopic energy converters in the near future.

  16. Irreversible entropy model for damage diagnosis in resistors

    SciTech Connect

    Cuadras, Angel Crisóstomo, Javier; Ovejas, Victoria J.; Quilez, Marcos

    2015-10-28

    We propose a method to characterize electrical resistor damage based on entropy measurements. Irreversible entropy and the rate at which it is generated are more convenient parameters than resistance for describing damage because they are essentially positive in virtue of the second law of thermodynamics, whereas resistance may increase or decrease depending on the degradation mechanism. Commercial resistors were tested in order to characterize the damage induced by power surges. Resistors were biased with constant and pulsed voltage signals, leading to power dissipation in the range of 4–8 W, which is well above the 0.25 W nominal power to initiate failure. Entropy was inferred from the added power and temperature evolution. A model is proposed to understand the relationship among resistance, entropy, and damage. The power surge dissipates into heat (Joule effect) and damages the resistor. The results show a correlation between entropy generation rate and resistor failure. We conclude that damage can be conveniently assessed from irreversible entropy generation. Our results for resistors can be easily extrapolated to other systems or machines that can be modeled based on their resistance.

  17. Irreversible Langevin samplers and variance reduction: a large deviations approach

    NASA Astrophysics Data System (ADS)

    Rey-Bellet, Luc; Spiliopoulos, Konstantinos

    2015-07-01

    In order to sample from a given target distribution (often of Gibbs type), the Monte Carlo Markov chain method consists of constructing an ergodic Markov process whose invariant measure is the target distribution. By sampling the Markov process one can then compute, approximately, expectations of observables with respect to the target distribution. Often the Markov processes used in practice are time-reversible (i.e. they satisfy detailed balance), but our main goal here is to assess and quantify how the addition of a non-reversible part to the process can be used to improve the sampling properties. We focus on the diffusion setting (overdamped Langevin equations) where the drift consists of a gradient vector field as well as another drift which breaks the reversibility of the process but is chosen to preserve the Gibbs measure. In this paper we use the large deviation rate function for the empirical measure as a tool to analyze the speed of convergence to the invariant measure. We show that the addition of an irreversible drift leads to a larger rate function and it strictly improves the speed of convergence of ergodic average for (generic smooth) observables. We also deduce from this result that the asymptotic variance decreases under the addition of the irreversible drift and we give an explicit characterization of the observables whose variance is not reduced reduced, in terms of a nonlinear Poisson equation. Our theoretical results are illustrated and supplemented by numerical simulations.

  18. Evidence of irreversible CO2 intercalation in montmorillonite

    SciTech Connect

    Romanov, V

    2013-02-13

    Mitigation of the global climate change via sequestration of anthropogenic carbon dioxide (CO2) in geologic formations requires assessment of the reservoir storage capacity and cap rock seal integrity. The typical cap rock is shale or mudstone rich in clay minerals that may significantly affect the effectiveness of the CO2 trapping. Specific objectives of this study were to conduct experimental investigation into the processes associated with CO2 and H2O trapped in swelling clay, namely, Wyoming and Texas montmorillonite powder. Combined (same-sample) multi-technique data ? manometric sorption isotherm hysteresis, diffuse reflectance infrared spectroscopy ?trapped CO2? fingerprints, irreversible X-ray diffraction patterns for the clay interlayer in intermediate hydration state, and HF acid digestion resulting in formation of non-extractable F:CO2 adducts ? corroborate a hypothesis that carbon dioxide molecules can be irreversibly trapped via anomalous extreme confinement in the galleries associated with montmorillonite interlayer, which may result in formation of carbonates in the longer term. Validation on Arizona montmorillonite lumps substantiated the evidence that such processes may occur in natural clay deposits but possibly on a different scale and at a different rate.

  19. Irreversibility in physics stemming from unpredictable symbol-handling agents

    NASA Astrophysics Data System (ADS)

    Myers, John M.; Madjid, F. Hadi

    2016-05-01

    The basic equations of physics involve a time variable t and are invariant under the transformation t --> -t. This invariance at first sight appears to impose time reversibility as a principle of physics, in conflict with thermodynamics. But equations written on the blackboard are not the whole story in physics. In prior work we sharpened a distinction obscured in today's theoretical physics, the distinction between obtaining evidence from experiments on the laboratory bench and explaining that evidence in mathematical symbols on the blackboard. The sharp distinction rests on a proof within the mathematics of quantum theory that no amount of evidence, represented in quantum theory in terms of probabilities, can uniquely determine its explanation in terms of wave functions and linear operators. Building on the proof we show here a role in physics for unpredictable symbol-handling agents acting both at the blackboard and at the workbench, communicating back and forth by means of transmitted symbols. Because of their unpredictability, symbol-handling agents introduce a heretofore overlooked source of irreversibility into physics, even when the equations they write on the blackboard are invariant under t --> -t. Widening the scope of descriptions admissible to physics to include the agents and the symbols that link theory to experiments opens up a new source of time-irreversibility in physics.

  20. When an adiabatic irreversible expansion or compression becomes reversible

    NASA Astrophysics Data System (ADS)

    Anacleto, Joaquim; Ferreira, J. M.; Soares, A. A.

    2009-05-01

    This paper aims to contribute to a better understanding of the concepts of a reversible process and entropy. For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure Pi to a final pressure Pf, by being placed in contact with a set of N work reservoirs with pressures decreasing (increasing) in a geometric or arithmetic progression. The gas entropy change ΔS is evaluated and it is clearly shown that ΔS > 0 for any finite N, but as the number of work reservoirs goes to infinity the entropy change goes to zero, i.e. the process becomes reversible. Additionally, this work draws attention to the work reservoir concept, which is virtually ignored in the literature, and to its analogy with the commonly used heat reservoir concept. Finally, it complements and reinforces an earlier study dealing with irreversible cooling or heating so that the synergy created by the two studies is important from both theoretical and educational standpoints.

  1. From Maximum Entropy Models to Non-Stationarity and Irreversibility

    NASA Astrophysics Data System (ADS)

    Cofre, Rodrigo; Cessac, Bruno; Maldonado, Cesar

    The maximum entropy distribution can be obtained from a variational principle. This is important as a matter of principle and for the purpose of finding approximate solutions. One can exploit this fact to obtain relevant information about the underlying stochastic process. We report here in recent progress in three aspects to this approach.1- Biological systems are expected to show some degree of irreversibility in time. Based on the transfer matrix technique to find the spatio-temporal maximum entropy distribution, we build a framework to quantify the degree of irreversibility of any maximum entropy distribution.2- The maximum entropy solution is characterized by a functional called Gibbs free energy (solution of the variational principle). The Legendre transformation of this functional is the rate function, which controls the speed of convergence of empirical averages to their ergodic mean. We show how the correct description of this functional is determinant for a more rigorous characterization of first and higher order phase transitions.3- We assess the impact of a weak time-dependent external stimulus on the collective statistics of spiking neuronal networks. We show how to evaluate this impact on any higher order spatio-temporal correlation. RC supported by ERC advanced Grant ``Bridges'', BC: KEOPS ANR-CONICYT, Renvision and CM: CONICYT-FONDECYT No. 3140572.

  2. Fluctuations in the number of irreversibly adsorbed particles

    NASA Astrophysics Data System (ADS)

    Adamczyk, Zbigniew; Szyk-Warszyńska, Lilianna; Siwek, B.; Weroński, P.

    2000-12-01

    Fluctuations in the number of colloid particles adsorbed irreversibly under pure diffusion transport conditions were determined as a function of surface density and ionic strength of the suspension. The experiments were carried out for monodisperse polystyrene latex particles of micrometer size range adsorbing irreversibly at mica surface. The surface density of adsorbed particles at various areas was determined using the direct microscope observation method. A new experimental cell was used enabling in situ observations of particles adsorption under conditions of negligible gravity effects. It was found that the particle density fluctuations for high ionic strength were in a good agreement with the theoretical results derived from the random sequential adsorption (RSA) model. Also, the theoretical results stemming from the equilibrium scaled particle theory reflected the experimental data satisfactorily. For lower ionic strength a deviation from the hard sphere behavior was experimentally demonstrated. This effect due to the repulsive electrostatic interactions was interpreted in terms of the effective hard particle concept. The universal dependence of variance on particle density obtained in this way was found in a good agreement with the RSA model for all ionic strength. These results proved that fluctuations in particle density of monolayer formed under diffusional conditions differ fundamentally from these obtained under ballistic transport conditions.

  3. Molecular control of irreversible bistability during trypanosome developmental commitment

    PubMed Central

    Domingo-Sananes, Maria Rosa; Szöőr, Balazs; Ferguson, Michael A.J.

    2015-01-01

    The life cycle of Trypanosoma brucei involves developmental transitions that allow survival, proliferation, and transmission of these parasites. One of these, the differentiation of growth-arrested stumpy forms in the mammalian blood into insect-stage procyclic forms, can be induced synchronously in vitro with cis-aconitate. Here, we show that this transition is an irreversible bistable switch, and we map the point of commitment to differentiation after exposure to cis-aconitate. This irreversibility implies that positive feedback mechanisms operate to allow commitment (i.e., the establishment of “memory” of exposure to the differentiation signal). Using the reversible translational inhibitor cycloheximide, we show that this signal memory requires new protein synthesis. We further performed stable isotope labeling by amino acids in cell culture to analyze synchronized parasite populations, establishing the protein and phosphorylation profile of parasites pre- and postcommitment, thereby defining the “commitment proteome.” Functional interrogation of this data set identified Nek-related kinase as the first-discovered protein kinase controlling the initiation of differentiation to procyclic forms. PMID:26483558

  4. Linear Dimensional Stability of Irreversible Hydrocolloid Materials Over Time.

    PubMed

    Garrofé, Analía B; Ferrari, Beatriz A; Picca, Mariana; Kaplan, Andrea E

    2015-12-01

    The aim of this study was to evaluate the linear dimensional stability of different irreversible hydrocolloid materials over time. A metal mold was designed with custom trays made of thermoplastic sheets (Sabilex, sheets 0.125 mm thick). Perforations were made in order to improve retention of the material. Five impressions were taken with each of the following: Kromopan 100 (LASCOD) [AlKr], which has dimensional stability of 100 hours, and Phase Plus (ZHERMACK) [AlPh], which has dimensional stability of 48 hours. Standardized digital photographs were taken at different time intervals (0, 15, 30, 45, 60, 120 minutes; 12, 24 and 96 hours), using an "ad-hoc" device. The images were analyzed with software (UTHSCSA Image Tool) by measuring the distance between intersection of the lines previously made at the top of the mold. The results were analyzed by ANOVA for repeated measures. Initial and final values were (mean and standard deviation): AlKr: 16.44 (0.22) and 16.34 (0.11), AlPh: 16.40 (0.06) and 16.18 (0.06). Statistical evaluation showed significant effect of material and time factors. Under the conditions in this study, time significantly affects the linear dimensional stability of irreversible hydrocolloid materials. PMID:27095627

  5. Essays on oil price volatility and irreversible investment

    NASA Astrophysics Data System (ADS)

    Pastor, Daniel J.

    In chapter 1, we provide an extensive and systematic evaluation of the relative forecasting performance of several models for the volatility of daily spot crude oil prices. Empirical research over the past decades has uncovered significant gains in forecasting performance of Markov Switching GARCH models over GARCH models for the volatility of financial assets and crude oil futures. We find that, for spot oil price returns, non-switching models perform better in the short run, whereas switching models tend to do better at longer horizons. In chapter 2, I investigate the impact of volatility on firms' irreversible investment decisions using real options theory. Cost incurred in oil drilling is considered sunk cost, thus irreversible. I collect detailed data on onshore, development oil well drilling on the North Slope of Alaska from 2003 to 2014. Volatility is modeled by constructing GARCH, EGARCH, and GJR-GARCH forecasts based on monthly real oil prices, and realized volatility from 5-minute intraday returns of oil futures prices. Using a duration model, I show that oil price volatility generally has a negative relationship with the hazard rate of drilling an oil well both when aggregating all the fields, and in individual fields.

  6. Linear Dimensional Stability of Irreversible Hydrocolloid Materials Over Time.

    PubMed

    Garrofé, Analía B; Ferrari, Beatriz A; Picca, Mariana; Kaplan, Andrea E

    2015-12-01

    The aim of this study was to evaluate the linear dimensional stability of different irreversible hydrocolloid materials over time. A metal mold was designed with custom trays made of thermoplastic sheets (Sabilex, sheets 0.125 mm thick). Perforations were made in order to improve retention of the material. Five impressions were taken with each of the following: Kromopan 100 (LASCOD) [AlKr], which has dimensional stability of 100 hours, and Phase Plus (ZHERMACK) [AlPh], which has dimensional stability of 48 hours. Standardized digital photographs were taken at different time intervals (0, 15, 30, 45, 60, 120 minutes; 12, 24 and 96 hours), using an "ad-hoc" device. The images were analyzed with software (UTHSCSA Image Tool) by measuring the distance between intersection of the lines previously made at the top of the mold. The results were analyzed by ANOVA for repeated measures. Initial and final values were (mean and standard deviation): AlKr: 16.44 (0.22) and 16.34 (0.11), AlPh: 16.40 (0.06) and 16.18 (0.06). Statistical evaluation showed significant effect of material and time factors. Under the conditions in this study, time significantly affects the linear dimensional stability of irreversible hydrocolloid materials.

  7. Voter model with arbitrary degree dependence: clout, confidence and irreversibility

    NASA Astrophysics Data System (ADS)

    Fotouhi, Babak; Rabbat, Michael G.

    2014-03-01

    The voter model is widely used to model opinion dynamics in society. In this paper, we propose three modifications to incorporate heterogeneity into the model. We address the corresponding oversimplifications of the conventional voter model which are unrealistic. We first consider the voter model with popularity bias. The influence of each node on its neighbors depends on its degree. We find the consensus probabilities and expected consensus times for each of the states. We also find the fixation probability, which is the probability that a single node whose state differs from every other node imposes its state on the entire system. In addition, we find the expected fixation time. Then two other extensions to the model are proposed and the motivations behind them are discussed. The first one is confidence, where in addition to the states of neighbors, nodes take their own state into account at each update. We repeat the calculations for the augmented model and investigate the effects of adding confidence to the model. The second proposed extension is irreversibility, where one of the states is given the property that once nodes adopt it, they cannot switch back. This is motivated by applications where, agents take an irreversible action such as seeing a movie, purchasing a music album online, or buying a new product. The dynamics of densities, fixation times and consensus times are obtained.

  8. Non-thermal irreversible electroporation for deep intracranial disorders.

    PubMed

    Garcia, Paulo A; Neal, Robert E; Rossmeisl, John H; Davalos, Rafael V

    2010-01-01

    Non-thermal irreversible electroporation (N-TIRE) is a new minimally invasive technique to kill undesirable tissue. We build on our previous intracranial studies in order to evaluate the possibility of using N-TIRE for deep intracranial disorders. In this manuscript we describe a minimally invasive computed tomography (CT) guided N-TIRE procedure in white matter. In addition, we report the electric field threshold needed for white matter ablation (630 - 875 V/cm) using four sets of twenty 50 µs pulses at a voltage-to-distance ratio of 1000 V/cm. We also confirm the non-thermal aspect of the technique with real time temperature data measured at the electrode-tissue interface. PMID:21095962

  9. Rat liver regeneration following ablation with irreversible electroporation

    PubMed Central

    Bruinsma, Bote G.; Jaramillo, Maria; Yarmush, Martin L.

    2016-01-01

    During the past decade, irreversible electroporation (IRE) ablation has emerged as a promising tool for the treatment of multiple diseases including hepatic cancer. However, the mechanisms behind the tissue regeneration following IRE ablation have not been investigated. Our results indicate that IRE treatment immediately kills the cells at the treatment site preserving the extracellular architecture, in effect causing in vivo decellularization. Over the course of 4 weeks, progenitor cell differentiation, through YAP and notch pathways, together with hepatocyte expansion led to almost complete regeneration of the ablated liver leading to the formation of hepatocyte like cells at the ablated zone. We did not observe significant scarring or tumor formation at the regenerated areas 6 months post IRE. Our study suggests a new model to study the regeneration of liver when the naïve extracellular matrix is decellularized in vivo with completely preserved extracellular architecture. PMID:26819842

  10. Immersion disinfection of irreversible hydrocolloid impressions. Part 1: Microbiology.

    PubMed

    Schwartz, R S; Bradley, D V; Hilton, T J; Kruse, S K

    1994-01-01

    This study evaluated the effectiveness of four disinfectants for irreversible hydrocolloid impressions. Impressions were made of a sterile metal model of the maxillary arch that had been contaminated with one of the following bacteria: Staphylococcus aureus, Salmonella choleraesuis, Pseudomonas aeruginosa, Mycobacterium bovis, or Bacillus subtilis. The impressions were cultured before and after immersion in one of the following disinfectants: lodofive, OMC II, 0.525% sodium hypochlorite, or Alcide LD. Alcide LD achieved a 4-log10 (99.99%) or greater reduction in colony forming units for all five organisms plus mixed oral flora. Sodium hypochlorite achieved a 4-log10 reduction in three of the five organisms and mixed oral flora. Iodofive and OMC II were ineffective against all test organisms and mixed oral flora. PMID:7802909

  11. Immersion disinfection of irreversible hydrocolloid impressions. Part 1: Microbiology.

    PubMed

    Schwartz, R S; Bradley, D V; Hilton, T J; Kruse, S K

    1994-01-01

    This study evaluated the effectiveness of four disinfectants for irreversible hydrocolloid impressions. Impressions were made of a sterile metal model of the maxillary arch that had been contaminated with one of the following bacteria: Staphylococcus aureus, Salmonella choleraesuis, Pseudomonas aeruginosa, Mycobacterium bovis, or Bacillus subtilis. The impressions were cultured before and after immersion in one of the following disinfectants: lodofive, OMC II, 0.525% sodium hypochlorite, or Alcide LD. Alcide LD achieved a 4-log10 (99.99%) or greater reduction in colony forming units for all five organisms plus mixed oral flora. Sodium hypochlorite achieved a 4-log10 reduction in three of the five organisms and mixed oral flora. Iodofive and OMC II were ineffective against all test organisms and mixed oral flora.

  12. Ac irreversibility line of bismuth-based high temperature superconductors

    SciTech Connect

    Mehdaoui, A.; Beille, J.; Berling, D.; Loegel, B.; Noudem, J.G.; Tournier, R.

    1997-09-01

    We discuss the magnetic properties of lead doped Bi-2223 bulk samples obtained through combined magnetic melt texturing and hot pressing (MMTHP). The ac complex susceptibility measurements are achieved over a broad ac field range (1 Oe{lt}h{sub ac}{lt}100 Oe) and show highly anisotropic properties. The intergranular coupling is improved in the direction perpendicular to the applied stress and magnetic field direction, and an intragranular loss peak is observed for the first time. A comparison is made with other bismuth-based compounds and it is shown that the MMTHP process shifts the ac irreversibility line (ac IL) toward higher fields. It is also shown that all the ac IL{close_quote}s for quasi 2D bismuth-based compounds show a nearly quadratic temperature dependence and deviate therefore strongly from the linear behavior observed in quasi 3D compounds and expected from a critical state model.{copyright} {ital 1997 Materials Research Society.}

  13. Sub-kBT micro-electromechanical irreversible logic gate

    PubMed Central

    López-Suárez, M.; Neri, I.

    2016-01-01

    In modern computers, computation is performed by assembling together sets of logic gates. Popular gates like AND, OR and XOR, processing two logic inputs and yielding one logic output, are often addressed as irreversible logic gates, where the sole knowledge of the output logic value is not sufficient to infer the logic value of the two inputs. Such gates are usually believed to be bounded to dissipate a finite minimum amount of energy determined by the input–output information difference. Here we show that this is not necessarily the case, by presenting an experiment where a OR logic gate, realized with a micro-electromechanical cantilever, is operated with energy well below the expected limit, provided the operation is slow enough and frictional phenomena are properly addressed. PMID:27350333

  14. Irreversible electroporation for the treatment of pancreatic neuroendocrine tumors

    PubMed Central

    Papamichail, Michail; Ali, Amir; Pizanias, Michail; Peddu, Praveen; Karani, John

    2016-01-01

    Backgrounds/Aims Resection or enucleation is currently the treatment of choice for small pancreatic neuroendocrine tumors (NETs). Irreversible electroporation is a novel ablative method that is used for locally advanced pancreatic adenocarcinoma, but little data exists for its use for pancreatic NETs. We report an early experience of IRE for early pancreatic NETs. Methods Between April 2014 and March 2015, 3 patients with small (<2 cm) pancreatic NETs were treated with percutaneous IRE. Results There were no adverse effects during the procedure. Mean hospital stay was 2.6 days. All patients remained disease free on 12-19 months follow up. One patient developed recurrent pancreatitis with pseudocyst formation. Conclusions IRE for small tumors of the pancreas is practical and may offer advantages over other thermal ablative techniques, since it preserves vital structures such as blood vessels, bile and pancreatic ducts. Further data regarding the long term disease free interval is required to establish efficacy.

  15. Sub-kBT micro-electromechanical irreversible logic gate.

    PubMed

    López-Suárez, M; Neri, I; Gammaitoni, L

    2016-01-01

    In modern computers, computation is performed by assembling together sets of logic gates. Popular gates like AND, OR and XOR, processing two logic inputs and yielding one logic output, are often addressed as irreversible logic gates, where the sole knowledge of the output logic value is not sufficient to infer the logic value of the two inputs. Such gates are usually believed to be bounded to dissipate a finite minimum amount of energy determined by the input-output information difference. Here we show that this is not necessarily the case, by presenting an experiment where a OR logic gate, realized with a micro-electromechanical cantilever, is operated with energy well below the expected limit, provided the operation is slow enough and frictional phenomena are properly addressed. PMID:27350333

  16. Typical pure nonequilibrium steady states and irreversibility for quantum transport.

    PubMed

    Monnai, Takaaki; Yuasa, Kazuya

    2016-07-01

    It is known that each single typical pure state in an energy shell of a large isolated quantum system well represents a thermal equilibrium state of the system. We show that such typicality holds also for nonequilibrium steady states (NESS's). We consider a small quantum system coupled to multiple infinite reservoirs. In the long run, the total system reaches a unique NESS. We identify a large Hilbert space from which pure states of the system are to be sampled randomly and show that the typical pure states well describe the NESS. We also point out that the irreversible relaxation to the unique NESS is important to the typicality of the pure NESS's. PMID:27575115

  17. Irreversible electroporation for the treatment of pancreatic neuroendocrine tumors

    PubMed Central

    Papamichail, Michail; Ali, Amir; Pizanias, Michail; Peddu, Praveen; Karani, John

    2016-01-01

    Backgrounds/Aims Resection or enucleation is currently the treatment of choice for small pancreatic neuroendocrine tumors (NETs). Irreversible electroporation is a novel ablative method that is used for locally advanced pancreatic adenocarcinoma, but little data exists for its use for pancreatic NETs. We report an early experience of IRE for early pancreatic NETs. Methods Between April 2014 and March 2015, 3 patients with small (<2 cm) pancreatic NETs were treated with percutaneous IRE. Results There were no adverse effects during the procedure. Mean hospital stay was 2.6 days. All patients remained disease free on 12-19 months follow up. One patient developed recurrent pancreatitis with pseudocyst formation. Conclusions IRE for small tumors of the pancreas is practical and may offer advantages over other thermal ablative techniques, since it preserves vital structures such as blood vessels, bile and pancreatic ducts. Further data regarding the long term disease free interval is required to establish efficacy. PMID:27621748

  18. Focal Therapy of Prostate Cancer Using Irreversible Electroporation.

    PubMed

    Valerio, Massimo; Ahmed, Hashim U; Emberton, Mark

    2015-09-01

    Focal therapy is a novel strategy that attempts to enhance the therapeutic ratio of standard radical treatment in prostate cancer. Irreversible electroporation (IRE) has some inherent characteristics that may be ideal for focal therapy. Precise confined ablation in the treatment area obtained via nonthermal damage with potential for minimal toxicity to surrounding structures may lead to optimal treatment with improved preservation of continence and erectile function. Initial data of focal IRE of the prostate are encouraging although further assessment is awaited to confirm these findings using robust methodology. In this article, we provide a comprehensive step-by-step description of our technique to deliver focal IRE in selected men with localized prostate cancer located in a discrete area of the prostate.

  19. Sub-kBT micro-electromechanical irreversible logic gate

    NASA Astrophysics Data System (ADS)

    López-Suárez, M.; Neri, I.; Gammaitoni, L.

    2016-06-01

    In modern computers, computation is performed by assembling together sets of logic gates. Popular gates like AND, OR and XOR, processing two logic inputs and yielding one logic output, are often addressed as irreversible logic gates, where the sole knowledge of the output logic value is not sufficient to infer the logic value of the two inputs. Such gates are usually believed to be bounded to dissipate a finite minimum amount of energy determined by the input-output information difference. Here we show that this is not necessarily the case, by presenting an experiment where a OR logic gate, realized with a micro-electromechanical cantilever, is operated with energy well below the expected limit, provided the operation is slow enough and frictional phenomena are properly addressed.

  20. Consequences of Irreversibility in Fundamental Models of Transcription

    NASA Astrophysics Data System (ADS)

    Sevier, Stuart; Levine, Herbert

    2015-03-01

    The ability to watch biochemical events play out at the single-molecule level has led to the discovery that transcription occurs in a noisy, ``bursty'' manner. Recently, as the single-molecule lens is placed over a larger number of organisms and genes, relationships between mean expression and noise beyond the ``bursty'' paradigm have emerged. Through a master-equation formulation of transcription we have found that many powerful physical principles relating to irreversibility seem to play a central role in the newly uncovered trends. Specifically, the relationships between mean expression and noise appears to be a direct consequence of network currents. We discuss how emphasizing the underlying principles in the models can explain recent experimental data and lead to a generalized view of transcription.

  1. Irreversible degradation of quantum coherence under relativistic motion

    NASA Astrophysics Data System (ADS)

    Wang, Jieci; Tian, Zehua; Jing, Jiliang; Fan, Heng

    2016-06-01

    We study the dynamics of quantum coherence under Unruh thermal noise and seek under which condition the coherence can be frozen in a relativistic setting. We find that the frozen condition is either (i) the initial state is prepared as an incoherence state or (ii) the detectors have no interaction with the external field. That is to say, the decoherence of the detectors' quantum state is irreversible under the influence of thermal noise induced by Unruh radiation. It is shown that quantum coherence approaches zero only in the limit of an infinite acceleration, while quantum entanglement could reduce to zero for a finite acceleration. It is also demonstrated that the robustness of quantum coherence is better than entanglement under the influence of the atom-field interaction for an extremely large acceleration. Therefore, quantum coherence is more robust than entanglement in an accelerating system and the coherence-type quantum resources are more accessible for relativistic quantum information processing tasks.

  2. Advertising and Irreversible Opinion Spreading in Complex Social Networks

    NASA Astrophysics Data System (ADS)

    Candia, Julián

    Irreversible opinion spreading phenomena are studied on small-world and scale-free networks by means of the magnetic Eden model, a nonequilibrium kinetic model for the growth of binary mixtures in contact with a thermal bath. In this model, the opinion of an individual is affected by those of their acquaintances, but opinion changes (analogous to spin flips in an Ising-like model) are not allowed. We focus on the influence of advertising, which is represented by external magnetic fields. The interplay and competition between temperature and fields lead to order-disorder transitions, which are found to also depend on the link density and the topology of the complex network substrate. The effects of advertising campaigns with variable duration, as well as the best cost-effective strategies to achieve consensus within different scenarios, are also discussed.

  3. Large-cell Monte Carlo renormalization of irreversible growth processes

    NASA Technical Reports Server (NTRS)

    Nakanishi, H.; Family, F.

    1985-01-01

    Monte Carlo sampling is applied to a recently formulated direct-cell renormalization method for irreversible, disorderly growth processes. Large-cell Monte Carlo renormalization is carried out for various nonequilibrium problems based on the formulation dealing with relative probabilities. Specifically, the method is demonstrated by application to the 'true' self-avoiding walk and the Eden model of growing animals for d = 2, 3, and 4 and to the invasion percolation problem for d = 2 and 3. The results are asymptotically in agreement with expectations; however, unexpected complications arise, suggesting the possibility of crossovers, and in any case, demonstrating the danger of using small cells alone, because of the very slow convergence as the cell size b is extrapolated to infinity. The difficulty of applying the present method to the diffusion-limited-aggregation model, is commented on.

  4. A systematic comprehensive approach to management of irreversible facial paralysis.

    PubMed

    Douglas, Raymond S; Gausas, Roberta E

    2003-02-01

    Irreversible facial palsy (IFP) presents a multitude of problems arising from a paretic periorbital and facial complex, the solutions to which cross the spectrum of multiple specialties. The process of facial rehabilitation can be simplified by subdividing the face into functional units. These units consist of the brow complex, the periorbital complex, the midface complex, and the lower face/oral complex. Although all of these units are interrelated and influence each other, careful study of the deformity and symptoms of each unit yields a coherent approach and customized surgical plan. The following provides a complete evaluation method for the surgeon to review and customize an approach to the individual patient's needs and desires. Facial rehabilitation must be tailored to each individual, addressing both functional as well as aesthetic concerns for each facial unit.

  5. The Social Cost of Stochastic and Irreversible Climate Change

    NASA Astrophysics Data System (ADS)

    Cai, Y.; Judd, K. L.; Lontzek, T.

    2013-12-01

    Many scientists are worried about climate change triggering abrupt and irreversible events leading to significant and long-lasting damages. For example, a rapid release of methane from permafrost may lead to amplified global warming, and global warming may increase the frequency and severity of heavy rainfall or typhoon, destroying large cities and killing numerous people. Some elements of the climate system which might exhibit such a triggering effect are called tipping elements. There is great uncertainty about the impact of anthropogenic carbon and tipping elements on future economic wellbeing. Any rational policy choice must consider the great uncertainty about the magnitude and timing of global warming's impact on economic productivity. While the likelihood of tipping points may be a function of contemporaneous temperature, their effects are long lasting and might be independent of future temperatures. It is assumed that some of these tipping points might occur even in this century, but also that their duration and post-tipping impact are uncertain. A faithful representation of the possibility of tipping points for the calculation of social cost of carbon would require a fully stochastic formulation of irreversibility, and accounting for the deep layer of uncertainties regarding the duration of the tipping process and also its economic impact. We use DSICE, a DSGE extension of the DICE2007 model of William Nordhaus, which incorporates beliefs about the uncertain economic impact of possible climate tipping events and uses empirically plausible parameterizations of Epstein-Zin preferences to represent attitudes towards risk. We find that the uncertainty associated with anthropogenic climate change imply carbon taxes much higher than implied by deterministic models. This analysis indicates that the absence of uncertainty in DICE2007 and similar IAM models may result in substantial understatement of the potential benefits of policies to reduce GHG emissions.

  6. Two studies of nonlinear processes in irreversible thermodynamics

    SciTech Connect

    Kestin, J.

    1992-01-01

    The investigation dealt with two lines of research into two well-defined problems of engineering science: a study of two-phase flow and of nonelastic deformations in structural solids. Both topics fall into the broad field of nonlinear irreversible processes. The study of two-phase flow resulted in a complete topological analysis of the canonical mathematical model of one-dimensional flow of a mixture of two phases, now predominantly used in industry, especially the nuclear industry. The topological analysis is confronted with the practice of discretizing the analytic model for the purpose of formulating a numerical computer code. It is shown that in the presence of singular points in the phase space of the differential equations of the model there occur spurious numerical solutions. Such solutions may contain segments which are correct approximations to the exact trajectory, but always include branches which are totally false and misleading. The topological method allows the operator to formulate a subroutine which eliminates spurious solutions. The study of inelastic deformations, i.e., of irreversible processes in structural solids provided a consistent presentation of the local-state approximation erroneously called the method of local equilibrium in the literature. The key concept which impedes the correct use of thermodynamics in this field is the definition of a measurable entropy of a nonequilibrium state. The local state approximation solves this problem by assigning to a nonequilibrium state n the entropy of the accompanying equilibrium state e. The two states, n and e, are linked by having the same values of a specified set of extensive properties. The same principle settles the comparison between the intensive properties of n and e, which are different.

  7. Inertial effects during irreversible meniscus reconfiguration in angular pores

    NASA Astrophysics Data System (ADS)

    Ferrari, Andrea; Lunati, Ivan

    2014-12-01

    In porous media, the dynamics of the invading front between two immiscible fluids is often characterized by abrupt reconfigurations caused by local instabilities of the interface. As a prototype of these phenomena we consider the dynamics of a meniscus in a corner as it can be encountered in angular pores. We investigate this process in detail by means of direct numerical simulations that solve the Navier-Stokes equations in the pore space and employ the Volume of Fluid method (VOF) to track the evolution of the interface. We show that for a quasi-static displacement, the numerically calculated surface energy agrees well with the analytical solutions that we have derived for pores with circular and square cross sections. However, the spontaneous reconfigurations are irreversible and cannot be controlled by the injection rate: they are characterized by the amount of surface energy that is spontaneously released and transformed into kinetic energy. The resulting local velocities can be orders of magnitude larger than the injection velocity and they induce damped oscillations of the interface that possess their own time scales and depend only on fluid properties and pore geometry. In complex media (we consider a network of cubic pores) reconfigurations are so frequent and oscillations last long enough that increasing inertial effects leads to a different fluid distribution by influencing the selection of the next pore to be invaded. This calls into question simple pore-filling rules based only on capillary forces. Also, we demonstrate that inertial effects during irreversible reconfigurations can influence the work done by the external forces that is related to the pressure drop in Darcy's law. This suggests that these phenomena have to be considered when upscaling multiphase flow because local oscillations of the menisci affect macroscopic quantities and modify the constitutive relationships to be used in macro-scale models. These results can be extrapolated to other

  8. Evaluation of irreversible JPEG compression for a clinical ultrasound practice.

    PubMed

    Persons, Kenneth R; Hangiandreou, Nicholas J; Charboneau, Nicholas T; Charboneau, J; James, E; Douglas, Bruce R; Salmon, Ann P; Knudsen, John M; Erickson, Bradley J

    2002-03-01

    A prior ultrasound study indicated that images with low to moderate levels of JPEG and wavelet compression were acceptable for diagnostic purposes. The purpose of this study is to validate this prior finding using the Joint Photographic Experts Group (JPEG) baseline compression algorithm, at a compression ratio of approximately 10:1, on a sufficiently large number of grayscale and color ultrasound images to attain a statistically significant result. The practical goal of this study is to determine if it is feasible for radiologists to use irreversibly compressed images as an integral part of the day to day ultrasound practice (ie, perform primary diagnosis with, and store irreversibly compressed images in the ultrasound PACS archive). In this study, 5 Radiologists were asked to review 300 grayscale and color static ultrasound images selected from 4 major anatomic groups. Each image was compressed and decompressed using the JPEG baseline compression algorithm at a fixed quality factor resulting in an average compression ratio of approximately 9:1. The images were presented in pairs (original and compressed) in a blinded fashion on a PACS workstation in the ultrasound reading areas, and radiologists were asked to pick which image they preferred in terms of diagnostic utility and their degree of certainty (on a scale from 1 to 4). Of the 1499 total readings, 50.17% (95% confidence intervals at 47.6%, and 52.7%) indicated a preference for the original image in the pair, and 49.83% (95% confidence intervals at 47.3%, and 52.0%) indicated a preference for the compressed image. These findings led the authors to conclude that static color and gray-scale ultrasound images compressed with JPEG at approximately 9:1 are statistically indistinguishable from the originals for primary diagnostic purposes. Based on the authors laboratory experience with compression and the results of this and other prior studies, JPEG compression is now being applied to all ultrasound images in

  9. The Impact of Uncertainty and Irreversibility on Investments in Online Learning

    ERIC Educational Resources Information Center

    Oslington, Paul

    2004-01-01

    Uncertainty and irreversibility are central to online learning projects, but have been neglected in the existing educational cost-benefit analysis literature. This paper builds some simple illustrative models of the impact of irreversibility and uncertainty, and shows how different types of cost and demand uncertainty can have substantial impacts…

  10. Flux creep and irreversibility line in high-temperature oxide superconductors

    SciTech Connect

    Matsushita, T.; Fujiyoshi, T.; Toko, K.; Yamafuji, K. )

    1990-05-14

    The irreversibility line in high-temperature oxide superconductors is theoretically investigated from a viewpoint of dependence on the flux-pinning strength and a general relation between the effective pinning potential and the critical current density is derived. It is shown that the irreversibility magnetic field at 77 K in strongly pinned oxide superconductors is sufficiently high for application.

  11. A minimal dissipation type-based classification in irreversible thermodynamics and microeconomics

    NASA Astrophysics Data System (ADS)

    Tsirlin, A. M.; Kazakov, V.; Kolinko, N. A.

    2003-10-01

    We formulate the problem of finding classes of kinetic dependencies in irreversible thermodynamic and microeconomic systems for which minimal dissipation processes belong to the same type. We show that this problem is an inverse optimal control problem and solve it. The commonality of this problem in irreversible thermodynamics and microeconomics is emphasized.

  12. Irreversible Entropy Production in Two-Phase Mixing Layers

    NASA Technical Reports Server (NTRS)

    Okongo, Nora

    2003-01-01

    This report presents a study of dissipation (irreversible production of entropy) in three-dimensional, temporal mixing layers laden with evaporating liquid drops. The purpose of the study is to examine the effects of evaporating drops on the development of turbulent features in flows. Direct numerical simulations were performed to analyze transitional states of three mixing layers: one without drops, and two that included drops at different initial mass loadings. Without drops, the dissipation is essentially due to viscous effects. It was found that in the presence of drops, the largest contribution to dissipation was made by heating and evaporation of the drops, and that at large length scales, this contribution is positive (signifying that the drops reduce turbulence), while at small scales, this contribution is negative (the drops increase turbulence). The second largest contribution to dissipation was found to be associated with the chemical potential, which leads to an increase in turbulence at large scales and a decrease in turbulence at small scales. The next smaller contribution was found to be that of viscosity. The fact that viscosity effects are only third in order of magnitude in the dissipation is in sharp contrast to the situation for the mixing layer without the drops. The next smaller contribution - that of the drag and momentum of the vapor from the drops - was found to be negative at lower mass loading but to become positive at higher mass loading.

  13. Electrical conductivity changes during irreversible electroporation treatment of brain cancer.

    PubMed

    Garcia, Paulo A; Rossmeisl, John H; Davalos, Rafael V

    2011-01-01

    Irreversible electroporation (IRE) is a new minimally invasive technique to kill tumors and other undesirable tissue in a non-thermal manner. During an IRE treatment, a series of short and intense electric pulses are delivered to the region of interest to destabilize the cell membranes in the tissue and achieve spontaneous cell death. The alteration of the cellular membrane results in a dramatic increase in electrical conductivity during IRE as in other electroporation-based-therapies. In this study, we performed the planning and execution of an IRE brain cancer treatment using MRI reconstructions of the tumor and a multichannel array that served as a stereotactic fiducial and electrode guide. Using the tumor reconstructions within our numerical simulations, we developed equations relating the increase in tumor conductivity to calculated currents and volumes of tumor treated with IRE. We also correlated the experimental current measured during the procedure to an increase in tumor conductivity ranging between 3.42-3.67 times the baseline conductivity, confirming the physical phenomenon that has been detected in other tissues undergoing similar electroporation-based treatments. PMID:22254416

  14. Time-dependent, irreversible entropy production and geodynamics.

    PubMed

    Regenauer-Lieb, Klaus; Karrech, Ali; Chua, Hui Tong; Horowitz, Franklin G; Yuen, Dave

    2010-01-13

    We present an application of entropy production as an abstraction tool for complex processes in geodynamics. Geodynamic theories are generally based on the principle of maximum dissipation being equivalent to the maximum entropy production. This represents a restriction of the second law of thermodynamics to its upper bound. In this paper, starting from the equation of motion, the first law of thermodynamics and decomposition of the entropy into reversible and irreversible terms,(1) we come up with an entropy balance equation in an integral form. We propose that the extrema of this equation give upper and lower bounds that can be used to constrain geodynamics solutions. This procedure represents an extension of the classical limit analysis theory of continuum mechanics, which considers only stress and strain rates. The new approach, however, extends the analysis to temperature-dependent problems where thermal feedbacks can play a significant role. We apply the proposed procedure to a simple convective/conductive heat transfer problem such as in a planetary system. The results show that it is not necessary to have a detailed knowledge of the material parameters inside the planet to derive upper and lower bounds for self-driven heat transfer processes. The analysis can be refined by considering precise dissipation processes such as plasticity and viscous creep. PMID:19948557

  15. Percolation of heteronuclear dimers irreversibly deposited on square lattices

    NASA Astrophysics Data System (ADS)

    Gimenez, M. C.; Ramirez-Pastor, A. J.

    2016-09-01

    The percolation problem of irreversibly deposited heteronuclear dimers on square lattices is studied. A dimer is composed of two segments, and it occupies two adjacent adsorption sites. Each segment can be either a conductive segment (segment type A ) or a nonconductive segment (segment type B ). Three types of dimers are considered: A A , B B , and A B . The connectivity analysis is carried out by accounting only for the conductive segments (segments type A ). The model offers a simplified representation of the problem of percolation of defective (nonideal) particles, where the presence of defects in the system is simulated by introducing a mixture of conductive and nonconductive segments. Different cases were investigated, according to the sequence of deposition of the particles, the types of dimers involved in the process, and the degree of alignment of the deposited objects. By means of numerical simulations and finite-size scaling analysis, the complete phase diagram separating a percolating from a nonpercolating region was determined for each case. Finally, the consistency of our results was examined by comparing with previous data in the literature for linear k -mers (particles occupying k adjacent sites) with defects.

  16. Non-Equilibrium Critical Behavior: An Extended Irreversible Thermodynamics Approach

    NASA Astrophysics Data System (ADS)

    Hernández-Lemus, Enrique; García-Colín, Leopoldo S.

    2006-11-01

    Critical phenomena in non-equilibrium systems have been studied by means of a wide variety of theoretical and experimental approaches. Mode-coupling, renormalization group, complex Lie algebras and diagrammatic techniques are some of the usual theoretical tools. Experimental studies include light and inelastic neutron scattering, X-ray photon correlation spectroscopy, microwave interferometry and several other techniques. Nevertheless, no conclusive treatment has been developed from the basic principles of a thermodynamic theory of irreversible processes. We have developed a formalism in which we obtain correlation functions as field averages of the associated functions. By applying such formalism, we attempt to find out whether the resulting correlation functions will inherit the mathematical properties (integrability, generalized homogeneity, scaling laws) of its parent potentials, and we also use these correlation functions to study the behavior of macroscopic systems far from equilibrium, especially in the neighborhood of critical points or dynamic phase transitions. As a working example, we will consider the mono-critical behavior of a non-equilibrium binary fluid mixture close to its consolute point.

  17. Scaling Law for Irreversible Entropy Production in Critical Systems

    NASA Astrophysics Data System (ADS)

    Hoang, Danh-Tai; Prasanna Venkatesh, B.; Han, Seungju; Jo, Junghyo; Watanabe, Gentaro; Choi, Mahn-Soo

    2016-06-01

    We examine the Jarzynski equality for a quenching process across the critical point of second-order phase transitions, where absolute irreversibility and the effect of finite-sampling of the initial equilibrium distribution arise in a single setup with equal significance. We consider the Ising model as a prototypical example for spontaneous symmetry breaking and take into account the finite sampling issue by introducing a tolerance parameter. The initially ordered spins become disordered by quenching the ferromagnetic coupling constant. For a sudden quench, the deviation from the Jarzynski equality evaluated from the ideal ensemble average could, in principle, depend on the reduced coupling constant ε0 of the initial state and the system size L. We find that, instead of depending on ε0 and L separately, this deviation exhibits a scaling behavior through a universal combination of ε0 and L for a given tolerance parameter, inherited from the critical scaling laws of second-order phase transitions. A similar scaling law can be obtained for the finite-speed quench as well within the Kibble-Zurek mechanism.

  18. Scaling Law for Irreversible Entropy Production in Critical Systems

    PubMed Central

    Hoang, Danh-Tai; Prasanna Venkatesh, B.; Han, Seungju; Jo, Junghyo; Watanabe, Gentaro; Choi, Mahn-Soo

    2016-01-01

    We examine the Jarzynski equality for a quenching process across the critical point of second-order phase transitions, where absolute irreversibility and the effect of finite-sampling of the initial equilibrium distribution arise in a single setup with equal significance. We consider the Ising model as a prototypical example for spontaneous symmetry breaking and take into account the finite sampling issue by introducing a tolerance parameter. The initially ordered spins become disordered by quenching the ferromagnetic coupling constant. For a sudden quench, the deviation from the Jarzynski equality evaluated from the ideal ensemble average could, in principle, depend on the reduced coupling constant ε0 of the initial state and the system size L. We find that, instead of depending on ε0 and L separately, this deviation exhibits a scaling behavior through a universal combination of ε0 and L for a given tolerance parameter, inherited from the critical scaling laws of second-order phase transitions. A similar scaling law can be obtained for the finite-speed quench as well within the Kibble-Zurek mechanism. PMID:27277558

  19. Prochloraz causes irreversible masculinization of zebrafish (Danio rerio).

    PubMed

    Baumann, Lisa; Knörr, Susanne; Keiter, Susanne; Nagel, Tina; Segner, Helmut; Braunbeck, Thomas

    2015-11-01

    The aim of the present study was to investigate the persistence of endocrine effects by prochloraz, a fungicide known to have multiple effects on the endocrine system of vertebrates. Since discontinuous exposure is particularly relevant in aquatic ecosystems, an exposure scenario with an exposure phase and a subsequent recovery period was chosen to assess the potential for reversibility of effects by prochloraz on the sexual development of zebrafish (Danio rerio). Zebrafish were exposed to different concentrations of prochloraz (10-300 μg/L) until 60 days post hatch (dph), which includes the period of sexual differentiation. For the subsequent 40 days, fish were either held in clean water for depuration or under further continuous exposure. Histological investigations of the gonads revealed persistent effects on sexual differentiation. The sex ratio was skewed towards males and significantly more intersex individuals were found after exposure to prochloraz at 60 dph. No intersex fish, but masculinized sex ratios were still present after the depuration period, documenting that prochloraz irreversibly affects the sexual development of zebrafish. PMID:25163568

  20. Use of irreversible electroporation in unresectable pancreatic cancer

    PubMed Central

    2015-01-01

    Irreversible electroporation is a non-thermal injury ablative modality that has been in clinical use since 2008 in the treatment of locally advanced soft tissue tumors. It has been reported to be utilized intraoperatively, laparoscopically or percutaneously. The method of action of IRE relies on a high voltage (maximum 3,000 volts) small microsecond pulse lengths (70 to 90 microseconds) to induce cell membrane porosity which leads to slow/protracted cell death over time. One of the largest unmet needs in oncology that IRE has been utilized is in locally advanced (stage III) pancreatic cancer. Recent studies have demonstrated the safety and palliation with encouraging improvement in overall survival. Its inherent limitation still remains tissue heterogeneity and the unique settings based on tumor histology and prior induction therapy. There remains a high technical demand of the end-user and the more extensive knowledge transfer which makes the learning curve longer in order to achieve appropriate and safe utilization. PMID:26151062

  1. Irreversible electroporation of locally advanced pancreatic neck/body adenocarcinoma

    PubMed Central

    2015-01-01

    Objective Irreversible electroporation (IRE) of locally advanced pancreatic adenocarcinoma of the neck has been used to palliate appropriate stage 3 pancreatic cancers without evidence of metastasis and who have undergone appropriate induction therapy. Currently there has not been a standardized reported technique for pancreatic mid-body tumors for patient selection and intra-operative technique. Patients Subjects are patients with locally advanced pancreatic adenocarcinoma of the body/neck who have undergone appropriate induction chemotherapy for a reasonable duration. Main outcome measures Technique of open IRE of locally advanced pancreatic adenocarcinoma of the neck/body is described, with the emphasis on intra-operative ultrasound and intra-operative electroporation management. Results The technique of open IRE of the pancreatic neck/body with bracketing of the celiac axis and superior mesenteric artery with continuous intraoperative ultrasound imaging and consideration of intraoperative navigational system is described. Conclusions IRE of locally advanced pancreatic adenocarcinoma of the body/neck is feasible for appropriate patients with locally advanced unresectable pancreatic cancer. PMID:26029461

  2. Scaling Law for Irreversible Entropy Production in Critical Systems.

    PubMed

    Hoang, Danh-Tai; Prasanna Venkatesh, B; Han, Seungju; Jo, Junghyo; Watanabe, Gentaro; Choi, Mahn-Soo

    2016-01-01

    We examine the Jarzynski equality for a quenching process across the critical point of second-order phase transitions, where absolute irreversibility and the effect of finite-sampling of the initial equilibrium distribution arise in a single setup with equal significance. We consider the Ising model as a prototypical example for spontaneous symmetry breaking and take into account the finite sampling issue by introducing a tolerance parameter. The initially ordered spins become disordered by quenching the ferromagnetic coupling constant. For a sudden quench, the deviation from the Jarzynski equality evaluated from the ideal ensemble average could, in principle, depend on the reduced coupling constant ε0 of the initial state and the system size L. We find that, instead of depending on ε0 and L separately, this deviation exhibits a scaling behavior through a universal combination of ε0 and L for a given tolerance parameter, inherited from the critical scaling laws of second-order phase transitions. A similar scaling law can be obtained for the finite-speed quench as well within the Kibble-Zurek mechanism. PMID:27277558

  3. Distribution function approach to irreversible adsorption of interacting colloidal particles

    NASA Astrophysics Data System (ADS)

    Faraudo, Jordi; Bafaluy, Javier

    2000-01-01

    A statistical-mechanical description of the irreversible adsorption of interacting colloidal particles is developed. Our approach describes in a consistent way the interaction of particles from the bulk with adsorbed particles during the transport process towards the adsorbing surface. The macroscopic physical quantities corresponding to the actual process are expressed as averages over simpler auxiliary processes which proceed in the presence of a fixed number n of adsorbed particles. The adsorption rate verifies a generalized Langmuir equation, in which the kinetic resistance (the inverse of the kinetic coefficient) is expressed as the sum of a diffusional resistance and a resistance due to interaction with adsorbed particles during the transport process (blocking effect). Contrary to previous approaches, the blocking effect is not due to geometrical exclusion, instead it measures how the transport from the bulk is affected by the adsorbed particles. From the general expressions obtained, we have derived coverage expansions for the adsorption rate and the surface correlation function. The theory is applied to the case of colloidal particles interacting through DLVO potentials. This form of the kinetic coefficient is shown to be in agreement with recent experimental results, in which RSA fails.

  4. The nineteenth century conflict between mechanism and irreversibility

    NASA Astrophysics Data System (ADS)

    van Strien, Marij

    2013-08-01

    The reversibility problem (better known as the reversibility objection) is usually taken to be an internal problem in the kinetic theory of gases, namely the problem of how to account for the second law of thermodynamics within this theory. Historically, it is seen as an objection that was raised against Boltzmann's kinetic theory of gases, which led Boltzmann to a statistical approach to the kinetic theory, culminating in the development of statistical mechanics. In this paper, I show that in the late nineteenth century, the reversibility problem had a much broader significance-it was widely discussed and certainly not only as an objection to Boltzmann's kinetic theory of gases. In this period, there was a conflict between mechanism and irreversibility in physics which was tied up with central issues in philosophy of science such as materialism, empiricism and the need for mechanistic foundations of physical theories, as well as with concerns about the heat death of the universe. I discuss how this conflict was handled by the major physicists of the period, such as Maxwell, Kelvin, Duhem, Poincaré, Mach and Planck, as well as by a number of lesser-known authors.

  5. Irreversible opinion spreading on scale-free networks

    NASA Astrophysics Data System (ADS)

    Candia, Julián

    2007-02-01

    We study the dynamical and critical behavior of a model for irreversible opinion spreading on Barabási-Albert (BA) scale-free networks by performing extensive Monte Carlo simulations. The opinion spreading within an inhomogeneous society is investigated by means of the magnetic Eden model, a nonequilibrium kinetic model for the growth of binary mixtures in contact with a thermal bath. The deposition dynamics, which is studied as a function of the degree of the occupied sites, shows evidence for the leading role played by hubs in the growth process. Systems of finite size grow either ordered or disordered, depending on the temperature. By means of standard finite-size scaling procedures, the effective order-disorder phase transitions are found to persist in the thermodynamic limit. This critical behavior, however, is absent in related equilibrium spin systems such as the Ising model on BA scale-free networks, which in the thermodynamic limit only displays a ferromagnetic phase. The dependence of these results on the degree exponent is also discussed for the case of uncorrelated scale-free networks.

  6. Generalized model and optimum performance of an irreversible quantum Brayton engine with spin systems.

    PubMed

    Wu, Feng; Chen, Lingen; Sun, Fengrui; Wu, Chih; Li, Qing

    2006-01-01

    The purpose of this paper is to establish a model of an irreversible quantum Brayton engine using many noninteracting spin systems as the working substance and consisting of two irreversible adiabatic and two isomagnetic field processes. The time evolution of the total magnetic moment M is determined by solving the generalized quantum master equation of an open system in the Heisenberg picture. The time of two irreversible adiabatic processes is considered based on finite-rate evolution. The relationship between the power output P and the efficiency eta for the irreversible quantum Brayton engine with spin systems is derived. The optimally operating region (or criteria) for the engine is determined. The influences of these important parameters on the performances (P and eta) of the engine are discussed. The results obtained herein will be useful for the further understanding and the selection of the optimal operating conditions for an irreversible quantum Brayton engine with spin systems.

  7. Macroscopic irreversibility and microscopic paradox: A Constructal law analysis of atoms as open systems

    PubMed Central

    Lucia, Umberto

    2016-01-01

    The relation between macroscopic irreversibility and microscopic reversibility is a present unsolved problem. Constructal law is introduced to develop analytically the Einstein’s, Schrödinger’s, and Gibbs’ considerations on the interaction between particles and thermal radiation (photons). The result leads to consider the atoms and molecules as open systems in continuous interaction with flows of photons from their surroundings. The consequent result is that, in any atomic transition, the energy related to the microscopic irreversibility is negligible, while when a great number of atoms (of the order of Avogadro’s number) is considered, this energy related to irreversibility becomes so large that its order of magnitude must be taken into account. Consequently, macroscopic irreversibility results related to microscopic irreversibility by flows of photons and amount of atoms involved in the processes. PMID:27762333

  8. Reanalysis of experiments to quantify irreversibility of pesticide sorption-desorption in soil.

    PubMed

    Suddaby, Laura A; Beulke, Sabine; van Beinum, Wendy; Celis, Rafael; Koskinen, William C; Brown, Colin D

    2013-03-01

    Previously published research used an isotope-exchange technique to measure irreversibility of pesticide sorption-desorption in soil. Results indicated significant irreversibility (6-51%) in sorption in five pesticide-soil systems measured over 72 h. Here, we propose a three-site model to reanalyze the experimental data. The model adds a slow but reversible binding on nonequilibrium sorption sites in addition to instantaneously reversible sites and irreversible sites. The model was able to match experimental data very closely, but only if irreversible sorption was assumed to be absent. Observed asymmetry in the binding of (12)C- and (14)C-pesticide was explained on the basis of nonattainment of sorption equilibrium over the study period. Results suggest that irreversible sorption may be less significant than previously considered with important implications for understanding the fate of pesticides applied to soil.

  9. Irreversible Collective Migration of Cyanobacteria in Eutrophic Conditions

    PubMed Central

    Dervaux, Julien; Mejean, Annick; Brunet, Philippe

    2015-01-01

    In response to natural or anthropocentric pollutions coupled to global climate changes, microorganisms from aquatic environments can suddenly accumulate on water surface. These dense suspensions, known as blooms, are harmful to ecosystems and signicantly degrade the quality of water resources. In order to determine the physico-chemical parameters involved in their formation and quantitatively predict their appearance, we successfully reproduced irreversible cyanobacterial blooms in vitro. By combining chemical, biochemical and hydrodynamic evidences, we identify a mechanism, unrelated to the presence of internal gas vesicles, allowing the sudden collective upward migration in test tubes of several cyanobacterial strains (Microcystis aeruginosa PCC 7005, Microcystis aeruginosa PCC 7806 and Synechocystis sp. PCC 6803). The final state consists in a foamy layer of biomass at the air-liquid interface, in which micro-organisms remain alive for weeks, the medium lying below being almost completely depleted of cyanobacteria. These "laboratory blooms" start with the aggregation of cells at high ionic force in cyanobacterial strains that produce anionic extracellular polymeric substances (EPS). Under appropriate conditions of nutrients and light intensity, the high photosynthetic activity within cell clusters leads the dissolved oxygen (DO) to supersaturate and to nucleate into bubbles. Trapped within the EPS, these bubbles grow until their buoyancy pulls the biomass towards the free surface. By investigating a wide range of spatially homogeneous environmental conditions (illumination, salinity, cell and nutrient concentration) we identify species-dependent thresholds and timescales for bloom formation. We conclude on the relevance of such results for cyanobacterial bloom formation in the environment and we propose an ecient method for biomass harvesting in bioreactors. PMID:25799424

  10. Irreversible Electroporation Near the Heart: Ventricular Arrhythmias Can Be Prevented With ECG Synchronization

    PubMed Central

    Deodhar, Ajita; Dickfeld, Timm; Single, Gordon W.; Hamilton, William C.; Thornton, Raymond H.; Sofocleous, Constantinos T.; Maybody, Majid; Gónen, Mithat; Rubinsky, Boris; Solomon, Stephen B.

    2013-01-01

    OBJECTIVE Irreversible electroporation is a nonthermal ablative tool that uses direct electrical pulses to create irreversible membrane pores and cell death. The ablation zone is surrounded by a zone of reversibly increased permeability; either zone can cause cardiac arrhythmias. Our purpose was to establish a safety profile for the use of irreversible electroporation close to the heart. MATERIALS and METHODS The effect of unsynchronized and synchronized (with the R wave on ECG) irreversible electroporation in swine lung and myocardium was studied in 11 pigs. Twelve lead ECG recordings were analyzed by an electrophysiologist for the presence of arrhythmia. Ventricular arrhythmias were categorized as major events. Minor events included all other dysrhythmias or ECG changes. Cardiac and lung tissue was submitted for histopathologic analysis. Electrical field modeling was performed to predict the distance from the applicators over which cells show electroporation-induced increased permeability. RESULTS At less than or equal to 1.7 cm from the heart, fatal (major) events occurred with all unsynchronized irreversible electroporation. No major and three minor events were seen with synchronized irreversible electroporation. At more than 1.7 cm from the heart, two minor events occurred with only unsynchronized irreversible electroporation. Electrical field modeling correlates well with the clinical results, revealing increased cell membrane permeability up to 1.7 cm away from the applicators. Complete lung ablation without intervening live cells was seen. No myocardial injury was seen. CONCLUSION Unsynchronized irreversible electroporation close to the heart can cause fatal ventricular arrhythmias. Synchronizing irreversible electroporation pulse delivery with absolute refractory period avoids significant cardiac arrhythmias. PMID:21343484

  11. Mesoscale modeling of irreversible volume growth in powders of anisotropic crystals

    SciTech Connect

    Gee, R; Maiti, A; Fried, L

    2006-05-05

    Careful thermometric analysis (TMA) on powders of micron-sized triamino-trinitrobenzene (TATB) crystallites are shown to display irreversible growth in volume when subjected to repeated cycles of heating and cooling. Such behavior is counter-intuitive to typical materials response to simulated annealing cycles in atomic-scale molecular dynamics. However, through coarse-grained simulations using a mesoscale Hamiltonian we quantitatively reproduce irreversible growth behavior in such powdered material. We demonstrate that irreversible growth happens only in the presence of intrinsic crystalline anisotropy, and is mediated by particles much smaller than the average crystallite size.

  12. Dermal and mucosal reactions to an antimicrobial irreversible hydrocolloid impression material: a clinical report.

    PubMed

    Baker, Philip S; Plummer, Kevin D; Parr, Gregory R; Parker, M Harry

    2006-03-01

    As an adjunct to infection control in dental impression procedures, several manufacturers have incorporated disinfectants into irreversible hydrocolloid impression materials. However, these compounds have been shown to be tissue irritants and capable of producing allergic reactions. An anonymous, self-administered questionnaire was distributed to 56 second-year dental students who had used an irreversible hydrocolloid containing a quaternary ammonium compound as an antimicrobial (Jeltrate Plus) to make impressions during a summer preclinical occlusion course. Within the limitations of this report, the incorporation of a quaternary ammonium compound into an irreversible hydrocolloid impression material resulted in a greater incidence of dermal and mucosal irritation.

  13. A Fingerprint Encryption Scheme Based on Irreversible Function and Secure Authentication

    PubMed Central

    Yu, Jianping; Zhang, Peng; Wang, Shulan

    2015-01-01

    A fingerprint encryption scheme based on irreversible function has been designed in this paper. Since the fingerprint template includes almost the entire information of users' fingerprints, the personal authentication can be determined only by the fingerprint features. This paper proposes an irreversible transforming function (using the improved SHA1 algorithm) to transform the original minutiae which are extracted from the thinned fingerprint image. Then, Chinese remainder theorem is used to obtain the biokey from the integration of the transformed minutiae and the private key. The result shows that the scheme has better performance on security and efficiency comparing with other irreversible function schemes. PMID:25873989

  14. A fingerprint encryption scheme based on irreversible function and secure authentication.

    PubMed

    Yang, Yijun; Yu, Jianping; Zhang, Peng; Wang, Shulan

    2015-01-01

    A fingerprint encryption scheme based on irreversible function has been designed in this paper. Since the fingerprint template includes almost the entire information of users' fingerprints, the personal authentication can be determined only by the fingerprint features. This paper proposes an irreversible transforming function (using the improved SHA1 algorithm) to transform the original minutiae which are extracted from the thinned fingerprint image. Then, Chinese remainder theorem is used to obtain the biokey from the integration of the transformed minutiae and the private key. The result shows that the scheme has better performance on security and efficiency comparing with other irreversible function schemes. PMID:25873989

  15. A fingerprint encryption scheme based on irreversible function and secure authentication.

    PubMed

    Yang, Yijun; Yu, Jianping; Zhang, Peng; Wang, Shulan

    2015-01-01

    A fingerprint encryption scheme based on irreversible function has been designed in this paper. Since the fingerprint template includes almost the entire information of users' fingerprints, the personal authentication can be determined only by the fingerprint features. This paper proposes an irreversible transforming function (using the improved SHA1 algorithm) to transform the original minutiae which are extracted from the thinned fingerprint image. Then, Chinese remainder theorem is used to obtain the biokey from the integration of the transformed minutiae and the private key. The result shows that the scheme has better performance on security and efficiency comparing with other irreversible function schemes.

  16. A Fragment-Based Method to Discover Irreversible Covalent Inhibitors of Cysteine Proteases

    PubMed Central

    2015-01-01

    A novel fragment-based drug discovery approach is reported which irreversibly tethers drug-like fragments to catalytic cysteines. We attached an electrophile to 100 fragments without significant alterations in the reactivity of the electrophile. A mass spectrometry assay discovered three nonpeptidic inhibitors of the cysteine protease papain. The identified compounds display the characteristics of irreversible inhibitors. The irreversible tethering system also displays specificity: the three identified papain inhibitors did not covalently react with UbcH7, USP08, or GST-tagged human rhinovirus 3C protease. PMID:24870364

  17. Inflammation Induces Irreversible Biophysical Changes in Isolated Nucleus Pulposus Cells

    PubMed Central

    Maidhof, Robert; Jacobsen, Timothy; Papatheodorou, Angelos; Chahine, Nadeen O.

    2014-01-01

    Intervertebral disc degeneration is accompanied by elevated levels of inflammatory cytokines that have been implicated in disease etiology and matrix degradation. While the effects of inflammatory stimulation on disc cell metabolism have been well-studied, their effects on cell biophysical properties have not been investigated. The hypothesis of this study is that inflammatory stimulation alters the biomechanical properties of isolated disc cells and volume responses to step osmotic loading. Cells from the nucleus pulposus (NP) of bovine discs were isolated and treated with either lipopolysaccharide (LPS), an inflammatory ligand, or with the recombinant cytokine TNF-α for 24 hours. We measured cellular volume regulation responses to osmotic loading either immediately after stimulation or after a 1 week recovery period from the inflammatory stimuli. Cells from each group were tested under step osmotic loading and the transient volume-response was captured via time-lapse microscopy. Volume-responses were analyzed using mixture theory framework to investigate two biomechanical properties of the cell, the intracellular water content and the hydraulic permeability. Intracellular water content did not vary between treatment groups, but hydraulic permeability increased significantly with inflammatory treatment. In the 1 week recovery group, hydraulic permeability remained elevated relative to the untreated recovery control. Cell radius was also significantly increased both after 24 hours of treatment and after 1 week recovery. A significant linear correlation was observed between hydraulic permeability and cell radius in untreated cells at 24 hours and at 1-week recovery, though not in the inflammatory stimulated groups at either time point. This loss of correlation between cell size and hydraulic permeability suggests that regulation of volume change is disrupted irreversibly due to inflammatory stimulation. Inflammatory treated cells exhibited altered F

  18. Irreversible entropy production in two-phase flows with evaporating drops

    NASA Technical Reports Server (NTRS)

    Bellan, J.; Okong'o, N. A.

    2002-01-01

    A derivation of the irreversible entropy production, that is the dissipation, in two-phase flows is presented for the purpose of examining the effect of evaporative-drop modulation of flows having turbulent features.

  19. The Effects of Internal and External Irreversibility of a Vapor Compression Refrigeration Cycle

    NASA Astrophysics Data System (ADS)

    Wang, Fu-Jen; Chiou, Jeng-Shing

    The concept of finite-time thermodynamics is employed to investigate the optimal refrigeration rate for an irreversible refrigeration cycle. The heat transfer between the system (internal) fluid and cooling (external) fluid takes place at the actual heat exchanger, which has the finite-size heat transfer area and the realistic heat transfer effectiveness. The internal irreversibility results from the compression process and the expansion process are also considered. The optimal refrigeration rate is calculated and expressed in terms of the irreversibility parameter (Ir), coefficient of performance (COP), the time ratio(γ) of heat transfer processes and the effectiveness of heat exchanger. The derived COP which consider both the external and internal irreversibility can thus be considered as the benchmark value for a practical refrigeration cycle, and the parametric study can provide the basis for both determination of optimal operating conditions and design of a practical refrigeration cycle.

  20. Timescales and Frequencies of Reversible and Irreversible Adhesion Events of Single Bacterial Cells.

    PubMed

    Hoffman, Michelle D; Zucker, Lauren I; Brown, Pamela J B; Kysela, David T; Brun, Yves V; Jacobson, Stephen C

    2015-12-15

    In the environment, most bacteria form surface-attached cell communities called biofilms. The attachment of single cells to surfaces involves an initial reversible stage typically mediated by surface structures such as flagella and pili, followed by a permanent adhesion stage usually mediated by polysaccharide adhesives. Here, we determine the absolute and relative timescales and frequencies of reversible and irreversible adhesion of single cells of the bacterium Caulobacter crescentus to a glass surface in a microfluidic device. We used fluorescence microscopy of C. crescentus expressing green fluorescent protein to track the swimming behavior of individual cells prior to adhesion, monitor the cell at the surface, and determine whether the cell reversibly or irreversibly adhered to the surface. A fluorescently labeled lectin that binds specifically to polar polysaccharides, termed holdfast, discriminated irreversible adhesion events from reversible adhesion events where no holdfast formed. In wild-type cells, the holdfast production time for irreversible adhesion events initiated by surface contact (23 s) was 30-times faster than the holdfast production time that occurs through developmental regulation (13 min). Irreversible adhesion events in wild-type cells (3.3 events/min) are 15-times more frequent than in pilus-minus mutant cells (0.2 events/min), indicating the pili are critical structures in the transition from reversible to irreversible surface-stimulated adhesion. In reversible adhesion events, the dwell time of cells at the surface before departing was the same for wild-type cells (12 s) and pilus-minus mutant cells (13 s), suggesting the pili do not play a significant role in reversible adhesion. Moreover, reversible adhesion events in wild-type cells (6.8 events/min) occur twice as frequently as irreversible adhesion events (3.3 events/min), demonstrating that most cells contact the surface multiple times before transitioning from reversible to

  1. Timescales and Frequencies of Reversible and Irreversible Adhesion Events of Single Bacterial Cells.

    PubMed

    Hoffman, Michelle D; Zucker, Lauren I; Brown, Pamela J B; Kysela, David T; Brun, Yves V; Jacobson, Stephen C

    2015-12-15

    In the environment, most bacteria form surface-attached cell communities called biofilms. The attachment of single cells to surfaces involves an initial reversible stage typically mediated by surface structures such as flagella and pili, followed by a permanent adhesion stage usually mediated by polysaccharide adhesives. Here, we determine the absolute and relative timescales and frequencies of reversible and irreversible adhesion of single cells of the bacterium Caulobacter crescentus to a glass surface in a microfluidic device. We used fluorescence microscopy of C. crescentus expressing green fluorescent protein to track the swimming behavior of individual cells prior to adhesion, monitor the cell at the surface, and determine whether the cell reversibly or irreversibly adhered to the surface. A fluorescently labeled lectin that binds specifically to polar polysaccharides, termed holdfast, discriminated irreversible adhesion events from reversible adhesion events where no holdfast formed. In wild-type cells, the holdfast production time for irreversible adhesion events initiated by surface contact (23 s) was 30-times faster than the holdfast production time that occurs through developmental regulation (13 min). Irreversible adhesion events in wild-type cells (3.3 events/min) are 15-times more frequent than in pilus-minus mutant cells (0.2 events/min), indicating the pili are critical structures in the transition from reversible to irreversible surface-stimulated adhesion. In reversible adhesion events, the dwell time of cells at the surface before departing was the same for wild-type cells (12 s) and pilus-minus mutant cells (13 s), suggesting the pili do not play a significant role in reversible adhesion. Moreover, reversible adhesion events in wild-type cells (6.8 events/min) occur twice as frequently as irreversible adhesion events (3.3 events/min), demonstrating that most cells contact the surface multiple times before transitioning from reversible to

  2. Substance P and CGRP expression in dental pulps with irreversible pulpitis.

    PubMed

    Sattari, Mandana; Mozayeni, Mohammad Ali; Matloob, Arash; Mozayeni, Maryam; Javaheri, Homan H

    2010-08-01

    The purpose of this study was to compare substance P (SP) and calcitonin gene-related peptide (CGRP) expression in pulp tissue with clinically diagnosed symptomatic and asymptomatic irreversible pulpitis. Healthy pulps acted as controls. Five normal pulps and 40 with irreversible pulpitis (20 symptomatic and 20 asymptomatic) were obtained from 45 different patients. SP and CGRP expression was determined by competition binding assays using enzyme immunoassay. anova and Mann-Whitney tests were used to ascertain if there were statistically significant differences between the groups. The results showed that neuropeptides were found in all pulp samples. The highest and the lowest expressions for SP and CGRP were found in symptomatic irreversible pulpitis and healthy pulps groups, respectively. The differences between healthy pulps and the groups of pulps having irreversible pulpitis were significant (P < 0.001). Although Mann-Whitney's post-hoc tests showed statistically significant differences in CGRP expression between two pulpitis groups (P < 0.05), differences in SP expression between symptomatic and asymptomatic irreversible pulpitis groups were not significant. This study demonstrated that the expression of CGRP and SP is significantly higher in pulps with irreversible pulpitis compared with healthy pulps. PMID:20666750

  3. Irreversible denaturation of maltodextrin glucosidase studied by differential scanning calorimetry, circular dichroism, and turbidity measurements.

    PubMed

    Goyal, Megha; Chaudhuri, Tapan K; Kuwajima, Kunihiro

    2014-01-01

    Thermal denaturation of Escherichia coli maltodextrin glucosidase was studied by differential scanning calorimetry, circular dichroism (230 nm), and UV-absorption measurements (340 nm), which were respectively used to monitor heat absorption, conformational unfolding, and the production of solution turbidity. The denaturation was irreversible, and the thermal transition recorded at scan rates of 0.5-1.5 K/min was significantly scan-rate dependent, indicating that the thermal denaturation was kinetically controlled. The absence of a protein-concentration effect on the thermal transition indicated that the denaturation was rate-limited by a mono-molecular process. From the analysis of the calorimetric thermograms, a one-step irreversible model well represented the thermal denaturation of the protein. The calorimetrically observed thermal transitions showed excellent coincidence with the turbidity transitions monitored by UV-absorption as well as with the unfolding transitions monitored by circular dichroism. The thermal denaturation of the protein was thus rate-limited by conformational unfolding, which was followed by a rapid irreversible formation of aggregates that produced the solution turbidity. It is thus important to note that the absence of the protein-concentration effect on the irreversible thermal denaturation does not necessarily means the absence of protein aggregation itself. The turbidity measurements together with differential scanning calorimetry in the irreversible thermal denaturation of the protein provided a very effective approach for understanding the mechanisms of the irreversible denaturation. The Arrhenius-equation parameters obtained from analysis of the thermal denaturation were compared with those of other proteins that have been reported to show the one-step irreversible thermal denaturation. Maltodextrin glucosidase had sufficiently high kinetic stability with a half-life of 68 days at a physiological temperature (37°C).

  4. Partial purification of the mu opioid receptor irreversibly labeled with (/sup 3/H)b-funaltrexamine

    SciTech Connect

    Liu-Chen, L.Y.; Phillips, C.A.; Tam, S.W.

    1986-03-01

    The mu opioid receptor in bovine striatal membranes was specifically and irreversibly labeled by incubation with 5 nM (/sup 3/H)..beta..-funaltrexamine (approx.-FNA) at 37/sup 0/C for 90 min in the presence of 100 mM NaCl. The specific and irreversible binding of (/sup 3/H)..beta..-FNA as defined by that blocked by 1 /sup +/M naloxone was about 60% of total irreversible binding. The specific irreversible binding was saturable, stereospecific, time-, temperature, and tissue-dependent. Mu opioid ligands were much more potent than delta or kappa ligands in inhibiting the specific irreversible labeling. SDS polyacrylamide gel electrophoresis of solubilized membranes in the presence of 2-mercaptoethanol yielded a major radiolabeled broad band of MW 68-97K daltons, characteristic of a glycoprotein band. This band was not observed in membranes labeled in the presence of excess unlabeled naloxone. The glycoprotein nature of the (/sup 3/H)..beta..-FNA-labeled opioid receptor was confirmed by its binding to a wheat germ agglutinin-Sepharose column and its elution with N-acetylglucosamine.

  5. Irreversibility line in superconductor as line of constant shielding current density

    SciTech Connect

    Goemoery, F.; Takacs, S.; Holubar, T.

    1997-06-01

    The irreversibility of magnetic properties of superconductors is due to the existence of macroscopic shielding currents persisting for some period of time. The same currents offer nearly lossless electricity transport. Thus, the extent of magnetic irreversibility is directly proportional to the current-carrying capacity of a superconductor. Because the current-carrying capacity is an intrinsic property of the material, various experimental techniques should give the same irreversibility line corresponding to the same macroscopic shielding current density. Following this approach, the authors compared the irreversibility lines obtained from AC susceptibility measurement with those determined from quasistatic magnetization loops recorded with the help of a SQUID susceptometer. An additional parameter which has to be comparable is the electrical field characterizing the rate of change of the magnetic field. Fulfilling these conditions of equivalency, the authors found that it is possible to explain the irreversibility lines obtained by various techniques and at different conditions by the same physical model. They demonstrate that for the data, taken within two orders of magnitude for the current density and more than seven orders of magnitude for the electrical field, a consistent picture expressing all the observed features by the same model can be found. Measurements are presented from YBCO samples.

  6. Irreversibility in Ba sub 0. 625 K sub 0. 375 BiO sub 3

    SciTech Connect

    Shi, D. ); Ling, X.S. ); Xu, M. ); Fang, M.M. ); Luo, S.; Budnick, J.I. ); Dabrowski, B.; Hinks, D.G.; Richards, D.R.; Zheng, Y. )

    1991-02-01

    An irreversibility line has been identified in bulk Ba{sub 0.625}K{sub 0.375}BiO{sub 3}, which follows the relation 1{minus}{ital T}/{ital T}{sub {ital c}}{similar to}{ital H}{sup 2/3}. According to the flux-creep model, the magnetic irreversibility is caused by thermally activated flux creep and is closely connected with the field-induced resistive broadening. However, previous resistivity measurements showed that the Ba{sub 0.625}K{sub 0.375}BiO{sub 3} system did not exhibit resistive transition broadening. Thus, an alternative explanation based on the Josephson-coupling model is suggested to interpret the irreversibility observed in Ba{sub 0.625}K{sub 0.375}BiO{sub 3}.

  7. Mechanism for membrane electroporation irreversibility under high-intensity, ultrashort electrical pulse conditions.

    PubMed

    Joshi, R P; Schoenbach, K H

    2002-11-01

    An improved electroporation model is used to address membrane irreversibility under ultrashort electric pulse conditions. It is shown that membranes can survive a strong electric pulse and recover provided the pore distribution has a relatively large spread. If, however, the population consists predominantly of larger radii pores, then irreversibility can result. Physically, such a distribution could arise if pores at adjacent sites coalesce. The requirement of close proximity among the pore sites is more easily satisfied in smaller organelles than in outer cell membranes. Model predictions are in keeping with recent observations of cell damage to intracellular organelles (e.g., mitochondria), without irreversible shock at the outer membranes, by a nanosecond, high-intensity electric pulse. This mechanism also explains the greater damage from multiple electric shocks.

  8. Mechanism for membrane electroporation irreversibility under high-intensity, ultrashort electrical pulse conditions

    NASA Astrophysics Data System (ADS)

    Joshi, R. P.; Schoenbach, K. H.

    2002-11-01

    An improved electroporation model is used to address membrane irreversibility under ultrashort electric pulse conditions. It is shown that membranes can survive a strong electric pulse and recover provided the pore distribution has a relatively large spread. If, however, the population consists predominantly of larger radii pores, then irreversibility can result. Physically, such a distribution could arise if pores at adjacent sites coalesce. The requirement of close proximity among the pore sites is more easily satisfied in smaller organelles than in outer cell membranes. Model predictions are in keeping with recent observations of cell damage to intracellular organelles (e.g., mitochondria), without irreversible shock at the outer membranes, by a nanosecond, high-intensity electric pulse. This mechanism also explains the greater damage from multiple electric shocks.

  9. Irreversible binding of zomepirac to plasma protein in vitro and in vivo.

    PubMed Central

    Smith, P C; McDonagh, A F; Benet, L Z

    1986-01-01

    Zomepirac is a nonsteroidal anti-inflammatory drug recently withdrawn from use because of an unexplained high incidence of immunological reactions. It is metabolized in humans to a reactive, unstable acyl glucuronide which accumulates in plasma. Because of the similarity of zomepirac glucuronide to bilirubin glucuronide in structure and stability and the documented irreversible binding of bilirubin to albumin through its acyl glucuronide, we studied the reaction of zomepirac acyl glucuronide with albumin in vitro from pH 5 to 9 and in vivo in six healthy human volunteers who had received a single 100-mg oral dose of zomepirac. Irreversible binding of zomepirac to protein was determined by exhaustive washing of protein, followed by hydrolysis of bound zomepirac-protein adduct with base, extraction of the liberated drug, and chromatographic measurement. Irreversible binding was observed both in vitro and in vivo. The extent of binding in vitro was time- and pH-dependent. In vitro drug binding was also observed for the isomers of zomepirac glucuronide which were formed by intramolecular acyl migration. Irreversible binding in vivo correlated with overall exposure to zomepirac glucuronide when exposure was expressed as the area under the plasma concentration vs. time curve. When probenecid (500 mg, twice daily), which decreases the plasma clearance of zomepirac glucuronide, was administered concurrently with zomepirac, irreversible binding of zomepirac was increased. The nature of the zomepirac protein binding is probably covalent. Formation of irreversibly protein-bound zomepirac occurs via the acyl glucuronide as previously shown for bilirubin glucuronide, and the reaction may be general for other drugs that are metabolized to acyl glucuronides. PMID:3949982

  10. Detailed Modeling and Irreversible Transfer Process Analysis of a Multi-Element Thermoelectric Generator System

    NASA Astrophysics Data System (ADS)

    Xiao, Heng; Gou, Xiaolong; Yang, Suwen

    2011-05-01

    Thermoelectric (TE) power generation technology, due to its several advantages, is becoming a noteworthy research direction. Many researchers conduct their performance analysis and optimization of TE devices and related applications based on the generalized thermoelectric energy balance equations. These generalized TE equations involve the internal irreversibility of Joule heating inside the thermoelectric device and heat leakage through the thermoelectric couple leg. However, it is assumed that the thermoelectric generator (TEG) is thermally isolated from the surroundings except for the heat flows at the cold and hot junctions. Since the thermoelectric generator is a multi-element device in practice, being composed of many fundamental TE couple legs, the effect of heat transfer between the TE couple leg and the ambient environment is not negligible. In this paper, based on basic theories of thermoelectric power generation and thermal science, detailed modeling of a thermoelectric generator taking account of the phenomenon of energy loss from the TE couple leg is reported. The revised generalized thermoelectric energy balance equations considering the effect of heat transfer between the TE couple leg and the ambient environment have been derived. Furthermore, characteristics of a multi-element thermoelectric generator with irreversibility have been investigated on the basis of the new derived TE equations. In the present investigation, second-law-based thermodynamic analysis (exergy analysis) has been applied to the irreversible heat transfer process in particular. It is found that the existence of the irreversible heat convection process causes a large loss of heat exergy in the TEG system, and using thermoelectric generators for low-grade waste heat recovery has promising potential. The results of irreversibility analysis, especially irreversible effects on generator system performance, based on the system model established in detail have guiding significance for

  11. Eigenvalue analysis of an irreversible random walk with skew detailed balance conditions.

    PubMed

    Sakai, Yuji; Hukushima, Koji

    2016-04-01

    An irreversible Markov-chain Monte Carlo (MCMC) algorithm with skew detailed balance conditions originally proposed by Turitsyn et al. is extended to general discrete systems on the basis of the Metropolis-Hastings scheme. To evaluate the efficiency of our proposed method, the relaxation dynamics of the slowest mode and the asymptotic variance are studied analytically in a random walk on one dimension. It is found that the performance in irreversible MCMC methods violating the detailed balance condition is improved by appropriately choosing parameters in the algorithm. PMID:27176439

  12. An Irreversible Constitutive Law for Modeling the Delamination Process using Interface Elements

    NASA Technical Reports Server (NTRS)

    Goyal, Vinay K.; Johnson, Eric R.; Davila, Carlos G.; Jaunky, Navin; Ambur, Damodar (Technical Monitor)

    2002-01-01

    An irreversible constitutive law is postulated for the formulation of interface elements to predict initiation and progression of delamination in composite structures. An exponential function is used for the constitutive law such that it satisfies a multi-axial stress criterion for the onset of delamination, and satisfies a mixed mode fracture criterion for the progression of delamination. A damage parameter is included to prevent the restoration of the previous cohesive state between the interfacial surfaces. To demonstrate the irreversibility capability of the constitutive law, steady-state crack growth is simulated for quasi-static loading-unloading cycle of various fracture test specimens.

  13. An Irreversible Constitutive Law for Modeling the Delamination Process Using Interface Elements

    NASA Technical Reports Server (NTRS)

    Goyal, Vinay K.; Johnson, Eric R.; Davila, Carlos G.; Jaunky, Navin; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    An irreversible constitutive law is postulated for the formulation of interface elements to predict initiation and progression of delamination in composite structures. An exponential function is used for the constitutive law such that it satisfies a multi-axial stress criterion for the onset of delamination, and satisfies a mixed mode fracture criterion for the progression of delamination. A damage parameter is included to prevent the restoration of the previous cohesive state between the interfacial surfaces. To demonstrate the irreversibility capability of the constitutive law, steady-state crack growth is simulated for quasi-static loading-unloading cycle of various fracture test specimens.

  14. Irreversibility in the microwave absorption of ceramic Y-Ba-Cu-O

    SciTech Connect

    Pakulis, E.J.

    1989-05-01

    We find that, for ceramic samples of YBa/sub 2/Cu/sub 3/O/sub x/, the microwave absorption in a dc magnetic field H and at a temperature T is different for field cooling than for zero field cooling, provided T is below a field-dependent irreversibility temperature. Since the microwaves probe only a layer at the surface of the sample, the irreversibility line in H-T space determined in this way is a property of the surface layer with a thickness given by the microwave skin depth. When the applied H is removed, we observe a remanent microwave absorption which decays logarithmically with time.

  15. Irreversibility and the Arrow of Time in a Quenched Quantum System.

    PubMed

    Batalhão, T B; Souza, A M; Sarthour, R S; Oliveira, I S; Paternostro, M; Lutz, E; Serra, R M

    2015-11-01

    Irreversibility is one of the most intriguing concepts in physics. While microscopic physical laws are perfectly reversible, macroscopic average behavior has a preferred direction of time. According to the second law of thermodynamics, this arrow of time is associated with a positive mean entropy production. Using a nuclear magnetic resonance setup, we measure the nonequilibrium entropy produced in an isolated spin-1/2 system following fast quenches of an external magnetic field. We experimentally demonstrate that it is equal to the entropic distance, expressed by the Kullback-Leibler divergence, between a microscopic process and its time reversal. Our result addresses the concept of irreversibility from a microscopic quantum standpoint. PMID:26588367

  16. The two-piston problem revisited: Generalization from reversible to irreversible expansion

    NASA Astrophysics Data System (ADS)

    Anacleto, Joaquim; Anacleto, Joaquim Alberto C.; Ferreira, J. M.

    2011-10-01

    We discuss the adiabatic two-piston problem for an ideal gas confined between two pistons of equal mass and extend recent work based on the reversible approximation. More realistic equations that account for the roles of the gas temperature and particle mass are applied to extend the analysis of the expansion of the gas from reversible to irreversible behavior to the limit of free expansion. The evolution of quantities, such as temperature, piston speed, adiabatic reversibility coefficients, and entropy, is obtained, and differences between the irreversible and the reversible solutions are investigated.

  17. The protein irreversible denaturation studied by means of the bending vibrational mode

    NASA Astrophysics Data System (ADS)

    Mallamace, Domenico; Corsaro, Carmelo; Vasi, Cirino; Vasi, Sebastiano; Dugo, Giacomo; Mallamace, Francesco

    2014-10-01

    We study by means of the infrared bending vibrational mode the microscopic mechanisms that are at the base of protein irreversible denaturation. In particular, we follow the thermal evolution of the Amide I and II vibrational modes of lysozyme residuals from ambient temperature toward the temperature of irreversible unfolding. Our results indicate that the thermal changes of the coupling, by means of the hydrogen bond, between hydration water molecules and the different chemical groups of the protein are the main microscopic mechanisms underlying the unfolding process.

  18. A tyrosine-reactive irreversible inhibitor for glutathione S-transferase Pi (GSTP1).

    PubMed

    Crawford, L A; Weerapana, E

    2016-05-24

    Glutathione S-transferase Pi (GSTP1) mediates cellular defense against reactive electrophiles. Here, we report LAS17, a dichlorotriazine-containing compound that irreversibly inhibits GSTP1 and is selective for GSTP1 within cellular proteomes. Mass spectrometry and mutational studies identified Y108 as the site of modification, providing a unique mode of GSTP1 inhibition. PMID:27113843

  19. Thermodynamics of Irreversible Processes. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Levin, Michael; Gallucci, V. F.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module describes the application of irreversible thermodynamics to biology. It begins with…

  20. A comparison of the anesthetic efficacy of articaine and lidocaine in patients with irreversible pulpitis.

    PubMed

    Tortamano, Isabel Peixoto; Siviero, Marcelo; Costa, Carina Gisele; Buscariolo, Inês Aparecida; Armonia, Paschoal Laércio

    2009-02-01

    The purpose of the present study was to compare the anesthetic efficacy of 4% articaine with 1:100,000 epinephrine with that of 2% lidocaine with 1:100,000 epinephrine during pulpectomy in patients with irreversible pulpitis in mandibular posterior teeth. Forty volunteers, patients with irreversible pulpitis admitted to the Emergency Center of the School of Dentistry at the University of São Paulo, randomly received a conventional inferior alveolar nerve block containing 3.6 mL of either 4% articaine with 1:100,000 epinephrine or 2% lidocaine with 1:100,000 epinephrine. During the subsequent pulpectomy, we recorded the patients' subjective assessments of lip anesthesia, the absence/presence of pulpal anesthesia through electric pulp stimulation, and the absence/presence of pain through a verbal analogue scale. All tested patients reported lip anesthesia after the application of either inferior alveolar nerve block. Regarding pulpal anesthesia success as measured with the pulp tester, the lidocaine solution had a higher success rate (70%) than the articaine solution (65%). For patients reporting none or mild pain during pulpectomy, the success rate of the articaine solution (65%) was higher than that of the lidocaine solution (45%). Yet, none of the observed differences between articaine and lidocaine were statistically significant. Apparently, therefore, both local anesthetic solutions had similar effects on the patients with irreversible pulpitis in mandibular posterior teeth. Neither of the solutions, however, resulted in an effective pain control during irreversible pulpitis treatments.

  1. Flux pinning and irreversibility in YBa sub 2 Cu sub 3 O sub 7 superconducting crystal

    SciTech Connect

    Sagdahl, L.T.; Gjolmesli, S.; Laegreid, T.; Fossheim, K.; Assmus, W. )

    1990-10-01

    Extensive ac-magnetic-permeability studies have been carried out on the irreversible behavior and flux dynamics in superconducting YBa{sub 2}Cu{sub 3}O{sub 7} crystals in external magnetic fields up to 7.5 T. From the analysis the irreversibility line {ital B}{sup *}({ital T}{sup *}) is found to scale as (1{minus}{ital T}{sup *}/{Tc}){sup {ital n}}, where {ital n}{approx equal}1.5 for fields higher than 1.5 T, and {ital n}{approx equal}1 for lower fields. The exponents are sensitive to the choice of {Tc}. The frequency dependence of the irreversibility temperature is carefully studied in the low-frequency region from 10 to 10{sup 5} Hz and is found to be logarithmic in the whole frequency range. The small logarithmic slope increases with increasing external field. The analysis is done within a flux-creep picture using a single-relaxation-time form for the complex permeability, and a vortex-glass model. The peak in the imaginary part of the permeability in different dc fields is successfully fitted to the predictions of the flux-creep model. A dynamical screening length is needed to account for the observed frequency dependence of the irreversibility temperature.

  2. 50 CFR 402.09 - Irreversible or irretrievable commitment of resources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE); ENDANGERED SPECIES COMMITTEE REGULATIONS SUBCHAPTER A INTERAGENCY COOPERATION-ENDANGERED SPECIES ACT OF 1973, AS AMENDED General § 402.09 Irreversible or... proposed species or proposed critical habitat under section 7(a)(4) of the Act....

  3. 50 CFR 402.09 - Irreversible or irretrievable commitment of resources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE); ENDANGERED SPECIES COMMITTEE REGULATIONS SUBCHAPTER A INTERAGENCY COOPERATION-ENDANGERED SPECIES ACT OF 1973, AS AMENDED General § 402.09 Irreversible or... proposed species or proposed critical habitat under section 7(a)(4) of the Act....

  4. 50 CFR 402.09 - Irreversible or irretrievable commitment of resources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE); ENDANGERED SPECIES COMMITTEE REGULATIONS SUBCHAPTER A INTERAGENCY COOPERATION-ENDANGERED SPECIES ACT OF 1973, AS AMENDED General § 402.09 Irreversible or... proposed species or proposed critical habitat under section 7(a)(4) of the Act....

  5. 50 CFR 402.09 - Irreversible or irretrievable commitment of resources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE); ENDANGERED SPECIES COMMITTEE REGULATIONS SUBCHAPTER A INTERAGENCY COOPERATION-ENDANGERED SPECIES ACT OF 1973, AS AMENDED General § 402.09 Irreversible or... proposed species or proposed critical habitat under section 7(a)(4) of the Act....

  6. 50 CFR 402.09 - Irreversible or irretrievable commitment of resources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE); ENDANGERED SPECIES COMMITTEE REGULATIONS SUBCHAPTER A INTERAGENCY COOPERATION-ENDANGERED SPECIES ACT OF 1973, AS AMENDED General § 402.09 Irreversible or... proposed species or proposed critical habitat under section 7(a)(4) of the Act....

  7. Seleninate in Place of Phosphate: Irreversible Inhibition of Protein Tyrosine Phosphatases

    SciTech Connect

    Abdo, Mohannad; Liu, Sijiu; Zhou, Bo; Walls, Chad D.; Wu, Li; Knapp, Spencer; Zhang, Zhong-Yin

    2009-02-16

    A homotyrosine based seleninic acid irreversibly inhibits protein tyrosine phosphatases by forming a covalent selenosulfide linkage with the active site cysteine sulfhydryl specifically. The details of the event are revealed by model synthetic studies and by kinetic, mass spectrometric, and crystallographic characterization.

  8. A tyrosine-reactive irreversible inhibitor for glutathione S-transferase Pi (GSTP1).

    PubMed

    Crawford, L A; Weerapana, E

    2016-05-24

    Glutathione S-transferase Pi (GSTP1) mediates cellular defense against reactive electrophiles. Here, we report LAS17, a dichlorotriazine-containing compound that irreversibly inhibits GSTP1 and is selective for GSTP1 within cellular proteomes. Mass spectrometry and mutational studies identified Y108 as the site of modification, providing a unique mode of GSTP1 inhibition.

  9. General Law of Electromagnetic Radiation Conversion Efficiency in Systems with Linear and Non-Linear Irreversibility

    NASA Astrophysics Data System (ADS)

    Chukova, Yu. P.

    2011-12-01

    It is shown, that the efficiency of conversion of solar radiation obeys the same law in alive and nonliving (technical) systems. For different processes in alive systems the evolution has selected different ranges of solar intensity and different conditions of irreversibility.

  10. Irreversible Loss of Vision in a Child due to Occipital Infarction after Gastroenteritis.

    PubMed

    Mansour, Ahmad M; Hasbini, Dana; Younis, Muhammad H; Bhatti, M Tariq

    2015-01-01

    A 2½-year-old girl developed a bilateral occipital infarct following severe gastroenteritis with bilateral vision of light perception. Evaluations for sickle cell anemia, hemolytic anemia and coagulopathies were negative. Cortical blindness is an uncommon but dramatic complication of gastroenteritis, hence the need of prompt hydration and other supportive measures to avoid irreversible visual loss or mental sequela.

  11. Irreversible Loss of Vision in a Child due to Occipital Infarction after Gastroenteritis

    PubMed Central

    Mansour, Ahmad M.; Hasbini, Dana; Younis, Muhammad H.; Bhatti, M. Tariq

    2015-01-01

    A 2½-year-old girl developed a bilateral occipital infarct following severe gastroenteritis with bilateral vision of light perception. Evaluations for sickle cell anemia, hemolytic anemia and coagulopathies were negative. Cortical blindness is an uncommon but dramatic complication of gastroenteritis, hence the need of prompt hydration and other supportive measures to avoid irreversible visual loss or mental sequela. PMID:25960732

  12. Expansion Work without the External Pressure and Thermodynamics in Terms of Quasistatic Irreversible Processes

    ERIC Educational Resources Information Center

    Schmidt-Rohr, Klaus

    2014-01-01

    We demonstrate that the formula for irreversible expansion work in most chemical thermodynamics textbooks does not apply during the expansion process. Instead of the "external pressure" P[subscript ext], the pressure P[subscript sys,mb] on the piston or other moving boundary (hence the subscript mb), which is nearly equal to the system…

  13. Irreversible Capacities of Graphite in Low Temperature Electrolytes for Lithium-Ion Batteries

    NASA Technical Reports Server (NTRS)

    Ratnakumar, B.; Smart, M.; Surampudi, S.; Wang, Y.; Zhang, X.; Greenbaum, S.; Hightower, A.; Ahn, C.; Fultz, B.

    1999-01-01

    Carbonaceous anode materials in lithium ion rechargeable cells experience irreversible capacity, mainly due to a consumption of lithium in the formation of surface passive films. The stability and kinetics of lithium intercalation into the carbon anodes are dictated by these films.

  14. Pinning and irreversibility in superconducting bulk MgB2 with added nanodiamonds

    NASA Astrophysics Data System (ADS)

    Gupta, Anurag; Narlikar, A. V.

    2009-12-01

    Resistance, R(T), and magnetization, M(B), studies on superconducting bulk MgB2 samples containing nanodiamonds (ND) as additives (wt% of ND: x = 0%, 1%, 3%, 5%, 7% and 10%) were recently published in two articles (Vajpayee et al 2007 Supercond. Sci. Technol. 20 S155, Vajpayee et al 2008 J. Appl. Phys. 103 07C708). The main observations reported were significant improvements in the critical current density Jc(B), irreversibility line Birr(T) and upper critical field Bc2(T) with ND addition. However, a closer look shows that as regards the potential of this technologically important material at higher magnetic fields and temperatures, there is still a lot of room for improvement. With that in mind we revisit the R(T) and M(B) data and analyze them, in the present work. We show that, despite ND addition, Jc depends strongly on B in the high field region and tends to vanish at irreversibility lines that lie deep, i.e. at around 0.3 Bc2(T), in the B-T phase diagram. The irreversibility lines, determined by R(T) \\to 0 in the presence of B, are found to lie at around 0.5 Bc2(T) in the phase diagram. These results for pinning and irreversibility lines are discussed in the light of various models such as those of surface sheath superconductivity, magnetically introduced percolation in polycrystalline MgB2, thermally assisted flux motion (TAFM) and a modified flux line shear mechanism. Our analysis hints at TAFM and weak pinning channels with distributed superconducting properties percolating in our samples determining the irreversibility and pinning properties.

  15. Using irreversible compression in digital radiology: a preliminary study of the opinions of radiologists

    NASA Astrophysics Data System (ADS)

    Seeram, Euclid

    2006-03-01

    The large volumes of digital images produced by digital imaging modalities in Radiology have provided the motivation for the development of picture archiving and communication systems (PACS) in an effort to provide an organized mechanism for digital image management. The development of more sophisticated methods of digital image acquisition (Multislice CT and Digital Mammography, for example), as well as the implementation and performance of PACS and Teleradiology systems in a health care environment, have created challenges in the area of image compression with respect to storing and transmitting digital images. Image compression can be reversible (lossless) or irreversible (lossy). While in the former, there is no loss of information, the latter presents concerns since there is a loss of information. This loss of information from diagnostic medical images is of primary concern not only to radiologists, but also to patients and their physicians. In 1997, Goldberg pointed out that "there is growing evidence that lossy compression can be applied without significantly affecting the diagnostic content of images... there is growing consensus in the radiologic community that some forms of lossy compression are acceptable". The purpose of this study was to explore the opinions of expert radiologists, and related professional organizations on the use of irreversible compression in routine practice The opinions of notable radiologists in the US and Canada are varied indicating no consensus of opinion on the use of irreversible compression in primary diagnosis, however, they are generally positive on the notion of the image storage and transmission advantages. Almost all radiologists are concerned with the litigation potential of an incorrect diagnosis based on irreversible compressed images. The survey of several radiology professional and related organizations reveals that no professional practice standards exist for the use of irreversible compression. Currently, the

  16. [Determination of irreversibility of clinical brain death. Electroencephalography and evoked potentials].

    PubMed

    Buchner, H; Ferbert, A

    2016-02-01

    Principally, in the fourth update of the rules for the procedure to finally determine the irreversible cessation of function of the cerebrum, the cerebellum and the brainstem, the importance of an electroencephalogram (EEG), somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) are confirmed. This paper presents the reliability and validity of the electrophysiological diagnosis, discusses the amendments in the fourth version of the guidelines and introduces the practical application, problems and sources of error.An EEG is the best established supplementary diagnostic method for determining the irreversibility of clinical brain death syndrome. It should be noted that residual brain activity can often persist for many hours after the onset of brain death syndrome, particularly in patients with primary brainstem lesions. The derivation and analysis of an EEG requires a high level of expertise to be able to safely distinguish artefacts from primary brain activity. The registration of EEGs to demonstrate the irreversibility of clinical brain death syndrome is extremely time consuming.The BAEPs can only be used to confirm the irreversibility of brain death syndrome in serial examinations or in the rare cases of a sustained wave I or sustained waves I and II. Very often, an investigation cannot be reliably performed because of existing sound conduction disturbances or failure of all potentials even before the onset of clinical brain death syndrome. This explains why BAEPs are only used in exceptional cases.The SEPs of the median nerve can be very reliably derived, are technically simple and with few sources of error. A serial investigation is not required and the time needed for examination is short. For these reasons SEPs are given preference over EEGs and BAEPs for establishing the irreversibility of clinical brain death syndrome. PMID:26785843

  17. Irreversible Heating Measurement with Microsecond Pulse Magnet: Example of the α-θ Phase Transition of Solid Oxygen

    NASA Astrophysics Data System (ADS)

    Nomura, Toshihiro; Matsuda, Yasuhiro H.; Takeyama, Shojiro; Kobayashi, Tatsuo C.

    2016-09-01

    Dissipation inevitably occurs in first-order phase transitions, leading to irreversible heating. Conversely, the irreversible heating effect may indicate the occurrence of the first-order phase transition. We measured the temperature change at the magnetic-field-induced α-θ phase transition of solid oxygen. A significant temperature increase from 13 to 37 K, amounting to 700 J/mol, due to irreversible heating was observed at the first-order phase transition. We argue that the hysteresis loss of the magnetization curve and the dissipative structural transformation account for the irreversible heating. The measurement of irreversible heating can be utilized to detect the first-order phase transition in combination with an ultrahigh magnetic fields generated in a time of µs order.

  18. Antibacterial efficacy and effect of Morinda citrifolia L. mixed with irreversible hydrocolloid for dental impressions: A randomized controlled trial

    PubMed Central

    Ahmed, A. Shafath; Charles, P. David; Cholan, R.; Russia, M.; Surya, R.; Jailance, L.

    2015-01-01

    Aim: This study aimed to evaluate whether the extract of Morinda citrifolia L. mixed with irreversible hydrocolloid powder decreases microbial contamination during impression making without affecting the resulting casts. Materials and Methods: Twenty volunteers were randomly divided into two groups (n = 10). Group A 30 ml extract of M. citrifolia L diluted in 30 ml of water was mixed to make the impression with irreversible hydrocolloid material. Group B 30 ml deionized water was mixed with irreversible hydrocolloid material to make the impressions following which the surface roughness and dimensional stability of casts were evaluated. Results: Extract of M. citrifolia L. mixed with irreversible hydrocolloid decreased the percentage of microorganisms when compared with water (P < 0.001) but did not affect the surface quality or dimensional stability of the casts. Conclusion: Mixing the extract of M. citrifolia L. with irreversible hydrocolloid powder is an alternative method to prevent contamination without sacrificing impression quality. PMID:26538926

  19. Assessing the role of feed water constituents in irreversible membrane fouling of pilot-scale ultrafiltration drinking water treatment systems.

    PubMed

    Peiris, R H; Jaklewicz, M; Budman, H; Legge, R L; Moresoli, C

    2013-06-15

    Fluorescence excitation-emission matrix (EEM) approach together with principal component analysis (PCA) was used for assessing hydraulically irreversible fouling of three pilot-scale ultrafiltration (UF) systems containing full-scale and bench-scale hollow fiber membrane modules in drinking water treatment. These systems were operated for at least three months with extensive cycles of permeation, combination of back-pulsing and scouring and chemical cleaning. The principal component (PC) scores generated from the PCA of the fluorescence EEMs were found to be related to humic substances (HS), protein-like and colloidal/particulate matter content. PC scores of HS- and protein-like matter of the UF feed water, when considered separately, showed reasonably good correlations with the rate of hydraulically irreversible fouling for long-term UF operations. In contrast, comparatively weaker correlations for PC scores of colloidal/particulate matter and the rate of hydraulically irreversible fouling were obtained for all UF systems. Since, individual correlations could not fully explain the evolution of the rate of irreversible fouling, multi-linear regression models were developed to relate the combined effect of HS-like, protein-like and colloidal/particulate matter PC scores to the rate of hydraulically irreversible fouling for each specific UF system. These multi-linear regression models revealed significant individual and combined contribution of HS- and protein-like matter to the rate of hydraulically irreversible fouling, with protein-like matter generally showing the greatest contribution. The contribution of colloidal/particulate matter to the rate of hydraulically irreversible fouling was not as significant. The addition of polyaluminum chloride, as coagulant, to UF feed appeared to have a positive impact in reducing hydraulically irreversible fouling by these constituents. The proposed approach has applications in quantifying the individual and synergistic

  20. Assessing the role of feed water constituents in irreversible membrane fouling of pilot-scale ultrafiltration drinking water treatment systems.

    PubMed

    Peiris, R H; Jaklewicz, M; Budman, H; Legge, R L; Moresoli, C

    2013-06-15

    Fluorescence excitation-emission matrix (EEM) approach together with principal component analysis (PCA) was used for assessing hydraulically irreversible fouling of three pilot-scale ultrafiltration (UF) systems containing full-scale and bench-scale hollow fiber membrane modules in drinking water treatment. These systems were operated for at least three months with extensive cycles of permeation, combination of back-pulsing and scouring and chemical cleaning. The principal component (PC) scores generated from the PCA of the fluorescence EEMs were found to be related to humic substances (HS), protein-like and colloidal/particulate matter content. PC scores of HS- and protein-like matter of the UF feed water, when considered separately, showed reasonably good correlations with the rate of hydraulically irreversible fouling for long-term UF operations. In contrast, comparatively weaker correlations for PC scores of colloidal/particulate matter and the rate of hydraulically irreversible fouling were obtained for all UF systems. Since, individual correlations could not fully explain the evolution of the rate of irreversible fouling, multi-linear regression models were developed to relate the combined effect of HS-like, protein-like and colloidal/particulate matter PC scores to the rate of hydraulically irreversible fouling for each specific UF system. These multi-linear regression models revealed significant individual and combined contribution of HS- and protein-like matter to the rate of hydraulically irreversible fouling, with protein-like matter generally showing the greatest contribution. The contribution of colloidal/particulate matter to the rate of hydraulically irreversible fouling was not as significant. The addition of polyaluminum chloride, as coagulant, to UF feed appeared to have a positive impact in reducing hydraulically irreversible fouling by these constituents. The proposed approach has applications in quantifying the individual and synergistic

  1. Lagrangian formulation of irreversible thermodynamics and the second law of thermodynamics

    SciTech Connect

    Glavatskiy, K. S.

    2015-05-28

    We show that the equations which describe irreversible evolution of a system can be derived from a variational principle. We suggest a Lagrangian, which depends on the properties of the normal and the so-called “mirror-image” system. The Lagrangian is symmetric in time and therefore compatible with microscopic reversibility. The evolution equations in the normal and mirror-imaged systems are decoupled and describe therefore independent irreversible evolution of each of the systems. The second law of thermodynamics follows from a symmetry of the Lagrangian. Entropy increase in the normal system is balanced by the entropy decrease in the mirror-image system, such that there exists an “integral of evolution” which is a constant. The derivation relies on the property of local equilibrium, which states that the local relations between the thermodynamic quantities in non-equilibrium are the same as in equilibrium.

  2. Irreversible electrical manipulation of magnetization on BiFeO{sub 3}-based heterostructures

    SciTech Connect

    Xu, Qingyu E-mail: jdu@nju.edu.cn; Xu, Zhenyu; He, Maocheng; Du, Jun E-mail: jdu@nju.edu.cn; Cao, Yanqiang

    2015-05-07

    We prepared several heterostructures, Co/Bi{sub 0.90}La{sub 0.10}FeO{sub 3} on surface oxidized Si or (111) SrTiO{sub 3} and NiFe/Bi{sub 0.90}La{sub 0.10}FeO{sub 3} on (001) SrTiO{sub 3} substrates using LaNiO{sub 3} as bottom electrode. With different strategies of voltage application, the exchange bias field H{sub E} decreased with increasing voltage irreversibly for all the heterostructures at room temperature. The chemical state at the NiFe/Bi{sub 0.90}La{sub 0.10}FeO{sub 3} interface was studied by X-ray photoelectron spectroscopy before and after the electrical manipulation. The oxidization of the metallic ferromagnetic layer at interface after the electrical manipulation has been confirmed, which might explain the irreversibility.

  3. Peptidyl cyclopropenones: Reversible inhibitors, irreversible inhibitors, or substrates of cysteine proteases?

    PubMed Central

    Cohen, Meital; Bretler, Uriel; Albeck, Amnon

    2013-01-01

    Peptidyl cyclopropenones were previously introduced as selective cysteine protease reversible inhibitors. In the present study we synthesized one such peptidyl cyclopropenone and investigated its interaction with papain, a prototype cysteine protease. A set of kinetics, biochemical, HPLC, MS, and 13C-NMR experiments revealed that the peptidyl cyclopropenone was an irreversible inhibitor of the enzyme, alkylating the catalytic cysteine. In parallel, this cyclopropenone also behaved as an alternative substrate of the enzyme, providing a product that was tentatively suggested to be either a spiroepoxy cyclopropanone or a gamma-lactone. Thus, a single family of compounds exhibits an unusual variety of activities, being reversible inhibitors, irreversible inhibitors and alternative substrates towards enzymes of the same family. PMID:23553793

  4. Immersion disinfection of irreversible hydrocolloid impressions with sodium hypochlorite. Part I: Microbiology.

    PubMed

    Beyerle, M P; Hensley, D M; Bradley, D V; Schwartz, R S; Hilton, T J

    1994-01-01

    Current American Dental Association infection control guidelines recommend immersion disinfection of irreversible hydrocolloid impressions, and this study further defines the parameters for use of sodium hypochlorite. Sodium hypochlorite has been shown to be an effective disinfectant for impressions; however, it has not been fully evaluated for optimum immersion time and concentration. In this study, irreversible hydrocolloid impressions contaminated with different bacteria were immersed in varying concentrations of sodium hypochlorite for 1, 5, or 10 minutes. Dilute solutions of sodium hypochlorite (0.525% or 0.0525%) produced a 4-log10 (99.99%) reduction in colony-forming units of Staphylococcus aureus, Salmonella choleraesuis, or Pseudomonas aeruginosa after 1 to 5 minutes' immersion. Full-strength sodium hypochlorite (5.25%) required 5 minutes to produce a 4-log10 reduction of Bacillus subtilis. A 4-log10 reduction of Mycobacterium bovis was not obtained under any conditions examined. PMID:7916888

  5. Immersion disinfection of irreversible hydrocolloid impressions with sodium hypochlorite. Part I: Microbiology.

    PubMed

    Beyerle, M P; Hensley, D M; Bradley, D V; Schwartz, R S; Hilton, T J

    1994-01-01

    Current American Dental Association infection control guidelines recommend immersion disinfection of irreversible hydrocolloid impressions, and this study further defines the parameters for use of sodium hypochlorite. Sodium hypochlorite has been shown to be an effective disinfectant for impressions; however, it has not been fully evaluated for optimum immersion time and concentration. In this study, irreversible hydrocolloid impressions contaminated with different bacteria were immersed in varying concentrations of sodium hypochlorite for 1, 5, or 10 minutes. Dilute solutions of sodium hypochlorite (0.525% or 0.0525%) produced a 4-log10 (99.99%) reduction in colony-forming units of Staphylococcus aureus, Salmonella choleraesuis, or Pseudomonas aeruginosa after 1 to 5 minutes' immersion. Full-strength sodium hypochlorite (5.25%) required 5 minutes to produce a 4-log10 reduction of Bacillus subtilis. A 4-log10 reduction of Mycobacterium bovis was not obtained under any conditions examined.

  6. Irreversible thermodynamic model for accelerated moment release and atmospheric radon concentration prior to large earthquakes

    NASA Astrophysics Data System (ADS)

    Kawada, Y.; Nagahama, H.; Omori, Y.; Yasuoka, Y.; Shinogi, M.

    2006-12-01

    Accelerated moment release is often preceded by large earthquakes, and defined by rate of cumulative Benioff strain following power-law time-to-failure relation. This temporal seismicity pattern is investigated in terms of irreversible thermodynamics model. The model is regulated by the Helmholtz free energy defined by the macroscopic stress-strain relation and internal state variables (generalized coordinates). Damage and damage evolution are represented by the internal state variables. In the condition, huge number of the internal state variables has each specific relaxation time, while a set of the time evolution shows a temporal power-law behavior. The irreversible thermodynamic model reduces to a fiber-bundle model and experimentally-based constitutive law of rocks, and predicts the form of accelerated moment release. Based on the model, we can also discuss the increase in atmospheric radon concentration prior to the 1995 Kobe earthquake.

  7. Irreversibility and thermoeconomics based design optimization of a ceramic heat exchanger

    SciTech Connect

    Ranasinghe, J.; Aceves-Saborio, S.; Reistad, G.M. )

    1989-10-01

    This paper illustrates the optimization procedure for heat exchangers residing in complex power plants. A specific case of optimizing a new technology ceramic heat exchanger, which is part of the complex power plant, is shown. The heat exchanger design methods presented are based on two different objective functions, namely, a modified irreversibility rate based objective function proposed by the authors in earlier work and an objective function based on thermoeconomics. This paper also extends existing work by illustrating a method to obtain the cost coefficients for thermoeconomic optimization, based on the use of an overall plant simulation model. A discussion on possible methods of improving the design guideposts obtained from irreversibility minimization analysis is presented.

  8. Irreversible visual loss and optic nerve dysfunction associated with central retinal vein occlusion in Waldenstrom Macroglobulinemia.

    PubMed

    Fadilah, S A W; Muhaya, M; Azlin, I

    2007-10-01

    Irreversible optic nerve dysfunction associated with central retinal vein occlusion (CRVO) is an unusual but important complication of Waldenstrom Macroglobulinemia (WM). Acute visual loss in CRVO is mainly due the severe macular oedema. However, ischaemic optic neuropathy needs to be considered in patients with CRVO when, (i) there is a relative afferent papillary defect and central scotoma, (ii) the visual acuity is not consistent with the retinal pathology, and (iii) the visual defects persisted despite resolution of macular oedema following treatment of the hyperviscosity state. The ischaemic type of CRVO is associated with a poor visual prognosis and the presenting visual acuity has a prognostic role. We report the first description of irreversible unilateral optic nerve damage associated with CRVO in a patient with WM. PMID:18551947

  9. On heat equation in the framework of classic irreversible thermodynamics with internal variables

    NASA Astrophysics Data System (ADS)

    Ciancio, Vincenzo; Restuccia, Liliana

    2016-06-01

    In this paper, we show that, using a procedure of classical irreversible thermodynamics (CIT) with internal variables, it is possible to describe the relaxation of thermal phenomena, obtaining some well known results of extended irreversible thermodynamics (EIT). In particular, we introduce as internal variables a vector and a second rank tensor, that influence the thermal transport phenomena, and we derive in the anisotropic and isotropic case, the phenomenological equations for these variables. In the case, in which the medium is isotropic, it is obtained that the total heat flux can be split in two parts: a first contribution J(0), governed by Fourier law, and a second contribution J(1), obeying Maxwell-Cattaneo-Vernotte (MCV) equation, in which a relaxation time is present. The obtained results may have applications in describing the thermal behavior in nanosystems (semiconductors, nanotubes,…), where the phenomena are fast and there are high-frequency thermal waves.

  10. Immersion disinfection of irreversible hydrocolloid impressions with sodium hypochlorite. Part II: Effect on gypsum.

    PubMed

    Vandewalle, K S; Charlton, D G; Schwartz, R S; Reagan, S E; Koeppen, R G

    1994-01-01

    This study investigated the effects of various immersion times and concentrations of sodium hypochlorite on irreversible hydrocolloid impressions and resultant gypsum casts. Irreversible hydrocolloid impressions of a test die were immersed for 1, 5, or 10 minutes in water (control), 5.25%, 0.525%, and 0.0525% sodium hypochlorite and then cast in a Type III stone and a Type V stone. Each stone specimen was evaluated for detail reproduction, dimensional change, surface roughness, and surface hardness. The results indicated that impressions may be immersed in sodium hypochlorite for any of the experimental times and concentrations without negative effects on Type V stone casts. However, immersion of impressions in 5.25% sodium hypochlorite causes some surface deterioration on Type III stone casts. PMID:7993542

  11. Suppression of irreversible capacity loss in Li-rich layered oxide by fluorine doping

    NASA Astrophysics Data System (ADS)

    Song, Jay Hyok; Kapylou, Andrei; Choi, Hee Sung; Yu, Byong Yong; Matulevich, Evegeniya; Kang, Sun Ho

    2016-05-01

    Li[Li1/6Ni1/6Co1/6Mn1/2]O2-xFx (x = 0.00 to 0.07) materials were synthesized with low temperature heat treatment (700 °C) and their electrochemical performances were evaluated. With the addition of fluorine, the reversible capacity significantly increased as the irreversibility was suppressed during the first cycle. The reduction of irreversibility was mainly attributed to the enhanced first cycle efficiency of Li2MnO3-like component after the fluorine addition. By combining results of the X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), In-situ X-ray absorption spectroscopy (XAS) analyses, and first principle calculations, it was proposed that the presence of fluorine facilitated the reduction of cobalt and manganese ions in Li-rich layered oxide, and that the reduced transition metal (TM) ions suppressed structural changes.

  12. In vivo efficacy of natural product-inspired irreversible kinase inhibitors.

    PubMed

    Barluenga, Sofia; Jogireddy, Rajamalleswaramma; Koripelly, Girish K; Winssinger, Nicolas

    2010-08-16

    Hypothemycin and related resorcylic acid lactones (RAL) bearing a cis-enone moiety have emerged as an alternative pharmacophore to heterocyclic motifs for kinase inhibition, and are endowed with a unique selectivity filter based on the irreversible reaction with a subset of the kinome bearing a suitably positioned cysteine residue. Two prototypical examples of "edited" RAL were evaluated for antitumoral, antimetastatic and antiangiogenic efficacy in an orthotopic murine renal cell carcinoma (RENCA) model. Both compounds (3 and 5) are good inhibitors of VEGFRs in vitro, and inhibited tumor growth in vivo with comparable efficacy to sunitinib, an FDA-approved VEGFRs inhibitor. Compound 3 promoted lung metastasis to a similar extent as sunitinib, while compound 5 strongly inhibited lung metastasis. This study attests to the potential of irreversible kinase inhibitors and molecular editing of natural pharmacophores and provides encouraging results to a clinically significant problem. PMID:20623569

  13. Work statistics, irreversible heat and correlations build-up in joining two spin chains

    NASA Astrophysics Data System (ADS)

    Apollaro, T. J. G.; Francica, Gianluca; Paternostro, Mauro; Campisi, Michele

    2015-10-01

    We investigate the influences of quantum many-body effects, such as criticality and the existence of factorization fields, in the thermodynamic cost of establishing a bonding link between two independent quantum spin chains. We provide a physical interpretation of the behavior of irreversible work spent in such a process by linking the phenomenology of such quantities to the properties of the spectrum of the system.

  14. Irreversible decay of nonlocal entanglement via a reservoir of a single degree of freedom

    SciTech Connect

    Vaglica, A.; Vetri, G.

    2007-06-15

    Recently, it has been realized that nonlocal disentanglement may take a finite time as opposite to the asymptotic decay of local coherences. We find in this paper that a sudden irreversible death of entanglement takes place in a two atom optical Stern-Gerlach model. In particular, the one degree nondissipative environment here considered suddenly destroys the initial entanglement of any Bell's states vertical bar {phi}{sup {+-}}> superposition.

  15. Rapid irreversible encephalopathy associated with anti-D immune globulin treatment for idiopathic thrombocytopenic purpura.

    PubMed

    Christopher, Kenneth; Horkan, Clare; Barb, Ilie T; Arbelaez, Christian; Hodgdon, Travis A; Yodice, Paul C

    2004-11-01

    Intravenous Rho (D) immune globulin (IV RhIG, WinRho SDF) has been shown to be a safe treatment for idiopathic thrombocytopenic purpura (ITP). Common side effects of IV RhIG include mild hemolysis, febrile reaction, and headache. Significant hemolysis with renal impairment following IV RhIG has been reported. We report a case of irreversible encephalopathy 48 hr following an infusion of IV RhIG for treatment of ITP.

  16. Fourteen. beta. -(bromoacetamido)morphine irreversibly labels. mu. opioid receptors in rat brain membranes

    SciTech Connect

    Bidlack, J.M.; Frey, D.K.; Seyed-Mozaffari, A.; Archer, S. )

    1989-05-16

    The binding properties of 14{beta}-(bromoacetamido)morphine (BAM) and the ability of BAM to irreversibly inhibit opioid binding to rat brain membranes were examined to characterize the affinity and selectivity of BAM as an irreversible affinity ligand for opioid receptors. BAM had the same receptor selectivity as morphine, with a 3-5-fold decrease in affinity for the different types of opioid receptors. When brain membranes were incubated with BAM, followed by extensive washing, opioid binding was restored to control levels. However, when membranes were incubated with dithiothreitol (DTT), followed by BAM, and subsequently washed, 90% of the 0.25 nM ({sup 3}H)(D-Ala{sup 2},(Me)Phe{sup 4},Gly(ol){sup 5})enkephalin (DAGO) binding was irreversibly inhibited as a result of the specific alkylation of a sulfhydryl group at the {mu} binding site. This inhibition was dependent on the concentrations of both DTT and BAM. The {mu} receptor specificity of BAM alkylation was demonstrated by the ability of BAM alkylated membranes to still bind the {delta}-selective peptide ({sup 3}H)(D-penicillamine{sup 2},D-penicillamine{sup 5})enkephalin (DPDPE) and (-)-({sup 3}H)bremazocine in the presence of {mu} and {delta} blockers, selective for {kappa} binding sites. Morphine and naloxone partially protected the binding site from alkylation with BAM, while ligands that did not bind to the {mu}s site did not afford protection. These studies have demonstrated that when a disulfide bond at or near {mu} opioid binding sites was reduced, BAM could then alkylate this site, resulting in the specific irreversible labeling of {mu} opioid receptors.

  17. Microbiome of Deep Dentinal Caries Lesions in Teeth with Symptomatic Irreversible Pulpitis

    PubMed Central

    Rôças, Isabela N.; Rachid, Caio T. C. C.; Lima, Kenio C.; Assunção, Isauremi V.; Gomes, Patrícia N.; Siqueira, José F.

    2016-01-01

    This study used a next-generation sequencing approach to identify the bacterial taxa occurring in the advanced front of caries biofilms associated with pulp exposure and irreversible pulpitis. Samples were taken from the deepest layer of dentinal caries lesions associated with pulp exposure in 10 teeth diagnosed with symptomatic irreversible pulpitis. DNA was extracted and the microbiome was characterized on the basis of the V4 hypervariable region of the 16S rRNA gene by using paired-end sequencing on Illumina MiSeq device. Bacterial taxa were mapped to 14 phyla and 101 genera composed by 706 different OTUs. Three phyla accounted for approximately 98% of the sequences: Firmicutes, Actinobacteria and Proteobacteria. These phyla were also the ones with most representatives at the species level. Firmicutes was the most abundant phylum in 9/10 samples. As for genera, Lactobacillus accounted for 42.3% of the sequences, followed by Olsenella (13.7%), Pseudoramibacter (10.7%) and Streptococcus (5.5%). Half of the samples were heavily dominated by Lactobacillus, while in the other half lactobacilli were in very low abundance and the most dominant genera were Pseudoramibacter, Olsenella, Streptococcus, and Stenotrophomonas. High bacterial diversity occurred in deep dentinal caries lesions associated with symptomatic irreversible pulpitis. The microbiome could be classified according to the relative abundance of Lactobacillus. Except for Lactobacillus species, most of the highly prevalent and abundant bacterial taxa identified in this study have been commonly detected in infected root canals. The detected taxa can be regarded as candidate pathogens for irreversible pulpitis and possibly the pioneers in pulp invasion to initiate endodontic infection. PMID:27135405

  18. Low-lying magnetic excitations, magnetic irreversibility and approach-to-saturation in nanocrystalline Ni

    NASA Astrophysics Data System (ADS)

    Venu Prakash, M. Pavan; Mathew, S. P.; Kaul, S. N.

    2013-06-01

    We demonstrate that the thermal demagnetization at temperatures T ≤ 350 K in pulse electrodeposited nanocrystalline (nc-) Ni samples with average grain size d = 10 nm and d = 20 nm is due to spin waves, spin-wave modes soften as d reduces, the interfacial/grain boundary magnetocrystalline anisotropy plays a crucial role in causing magnetic irreversibility at fields H ≤ 2 kOe and in governing the approach-to-saturation of magnetization in nc-Ni.

  19. Hydrophilic fraction of natural organic matter causing irreversible fouling of microfiltration and ultrafiltration membranes.

    PubMed

    Yamamura, Hiroshi; Okimoto, Kenji; Kimura, Katsuki; Watanabe, Yoshimasa

    2014-05-01

    Although membrane filtration is a promising technology in the field of drinking water treatment, persistent membrane fouling remains a major disadvantage. For more efficient operation, causative agents of membrane fouling need to be identified. Membrane fouling can be classified into physically reversible and irreversible fouling on basis of the removability of the foulants by physical cleaning. Four types of natural organic matter (NOM) in river water used as a source of drinking water were fractionated into hydrophobic and hydrophilic fractions, and their potential to develop irreversible membrane fouling was evaluated by a bench-scale filtration experiment together with spectroscopic and chromatographic analyses. In this study, only dissolved NOM was investigated without consideration of interactions of NOM fractions with particulate matter. Results demonstrated that despite identical total organic carbon (TOC), fouling development trends were significantly different between hydrophilic and hydrophobic fractions. The hydrophobic fractions did not increase membrane resistance, while the hydrophilic fractions caused severe loss of membrane permeability. These results were identical with the case when the calcium was added to hydrophobic and hydrophilic fractions. The largest difference in NOM characteristics between hydrophobic and hydrophilic fractions was the presence or absence of macromolecules; the primary constituent causing irreversible fouling was inferred to be "biopolymers", including carbohydrates and proteins. In addition, the results demonstrated that the extent of irreversible fouling was considerably different depending on the combination of membrane materials and NOM characteristics. Despite identical nominal pore size (0.1 μm), a polyvinylidene fluoride (PVDF) membrane was found to be more rapidly fouled than a PE membrane. This is probably explained by the generation of strong hydrogen bonding between hydroxyl groups of biopolymers and fluorine

  20. Hydrophilic fraction of natural organic matter causing irreversible fouling of microfiltration and ultrafiltration membranes.

    PubMed

    Yamamura, Hiroshi; Okimoto, Kenji; Kimura, Katsuki; Watanabe, Yoshimasa

    2014-05-01

    Although membrane filtration is a promising technology in the field of drinking water treatment, persistent membrane fouling remains a major disadvantage. For more efficient operation, causative agents of membrane fouling need to be identified. Membrane fouling can be classified into physically reversible and irreversible fouling on basis of the removability of the foulants by physical cleaning. Four types of natural organic matter (NOM) in river water used as a source of drinking water were fractionated into hydrophobic and hydrophilic fractions, and their potential to develop irreversible membrane fouling was evaluated by a bench-scale filtration experiment together with spectroscopic and chromatographic analyses. In this study, only dissolved NOM was investigated without consideration of interactions of NOM fractions with particulate matter. Results demonstrated that despite identical total organic carbon (TOC), fouling development trends were significantly different between hydrophilic and hydrophobic fractions. The hydrophobic fractions did not increase membrane resistance, while the hydrophilic fractions caused severe loss of membrane permeability. These results were identical with the case when the calcium was added to hydrophobic and hydrophilic fractions. The largest difference in NOM characteristics between hydrophobic and hydrophilic fractions was the presence or absence of macromolecules; the primary constituent causing irreversible fouling was inferred to be "biopolymers", including carbohydrates and proteins. In addition, the results demonstrated that the extent of irreversible fouling was considerably different depending on the combination of membrane materials and NOM characteristics. Despite identical nominal pore size (0.1 μm), a polyvinylidene fluoride (PVDF) membrane was found to be more rapidly fouled than a PE membrane. This is probably explained by the generation of strong hydrogen bonding between hydroxyl groups of biopolymers and fluorine

  1. Calcium-Enriched Mixture Pulpotomy of Primary Molar Teeth with Irreversible Pulpitis. A Clinical Study

    PubMed Central

    Memarpour, Mahtab; Fijan, Soleiman; Asgary, Saeed; Keikhaee, Marzieh

    2016-01-01

    Objectives: To evaluate the outcome of vital pulp therapy in primary teeth with irreversible pulpitis by using calcium-enriched mixture (CEM) cement according to clinical and radiographic assessment. Participants and Methods: Fifty primary molar teeth with irreversible pulpitis in 50 children aged 6-8 years underwent pulpotomy using CEM cement as the dressing material. Following pulpotomy, pain intensity was evaluated by use of a visual analog scale at 1 and 7 days from the treatment and in clinical appointments at 3, 6 and 12 months after baseline. Radiographic evaluation was performed at 6 and 12 months. Data were analyzed using the McNemar test. Results: A total of 42 children (mean age 7.26 ± 0.82 year) completed the study. After one day treatment 56 % of children reported complete relief of pain and after 7 days 62% reported the same. However, two children complained of increased pain 1 day after treatment. None of the children reported pain in the subsequent appointments. One child complained of tenderness in percussion after 6 months. Pulp canal obliteration was the most common change in the radiographic assessment. There was no significant difference between clinical (92.8%) and radiographic (90.4%) success (p=0.990). Conclusion: Pulpotomy using CEM cement could present a successful treatment in primary molar teeth with irreversible pulpitis. PMID:27326265

  2. Estimating Temperature Rise Due to Flashlamp Heating Using Irreversible Temperature Indicators

    NASA Technical Reports Server (NTRS)

    Koshti, Ajay M.

    1999-01-01

    One of the nondestructive thermography inspection techniques uses photographic flashlamps. The flashlamps provide a short duration (about 0.005 sec) heat pulse. The short burst of energy results in a momentary rise in the surface temperature of the part. The temperature rise may be detrimental to the top layer of the part being exposed. Therefore, it is necessary to ensure the nondestructive nature of the technique. Amount of the temperature rise determines whether the flashlamp heating would be detrimental to the part. A direct method for the temperature measurement is to use of an infrared pyrometer that has much shorter response time than the flash duration. In this paper, an alternative technique is given using the irreversible temperature 'indicators. This is an indirect technique and it measures the temperature rise on the irreversible temperature indicators and computes the incident heat flux. Once the heat flux is known, the temperature rise on the part can be computed. A wedge shaped irreversible temperature indicator for measuring the heat flux is proposed. A procedure is given to use the wedge indicator.

  3. The influence of impression trays on the accuracy of stone casts poured from irreversible hydrocolloid impressions.

    PubMed

    Mendez, A J

    1985-09-01

    An investigation was conducted to determine which of four commonly used impression trays yields the best results when making irreversible hydrocolloid impressions. This objective was achieved by evaluating the comparative accuracy of stone casts obtained from irreversible hydrocolloid impressions made with trays of different characteristics. The following conclusions are drawn from this study. Some kind of distortion can be expected in irreversible hydrocolloid impressions with the use of any of the tested impression trays. The perforated trays (B and D) reproduce more accurately the distances along the length and the width of the arch than the nonperforated trays (A and C). The depth of the palatal vault (distance f-g) is reproduced most accurately by the Rim-lock nonperforated tray (A) followed closely by the stock perforated (B) and the custom nonperforated (C) trays. Under the conditions of this study, all the impressions had a tendency to be oversized except the impressions made with the stock perforated tray (B). Those impressions were slightly undersized for all but two measured distances. Clinically significant inaccuracies produced by any of the four tested impression trays were not found in this study.

  4. Irreversibilities and efficiency at maximum power of heat engines: the illustrative case of a thermoelectric generator.

    PubMed

    Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph

    2012-03-01

    Energy conversion efficiency at maximum output power, which embodies the essential characteristics of heat engines, is the main focus of the present work. The so-called Curzon and Ahlborn efficiency η(CA) is commonly believed to be an absolute reference for real heat engines; however, a different but general expression for the case of stochastic heat engines, η(SS), was recently found and then extended to low-dissipation engines. The discrepancy between η(CA) and η(SS) is here analyzed considering different irreversibility sources of heat engines, of both internal and external types. To this end, we choose a thermoelectric generator operating in the strong-coupling regime as a physical system to qualitatively and quantitatively study the impact of the nature of irreversibility on the efficiency at maximum output power. In the limit of pure external dissipation, we obtain η(CA), while η(SS) corresponds to the case of pure internal dissipation. A continuous transition between from one extreme to the other, which may be operated by tuning the different sources of irreversibility, also is evidenced.

  5. Evidence for irreversible inhibition of glycogen synthase kinase-3β by tideglusib.

    PubMed

    Domínguez, Juan Manuel; Fuertes, Ana; Orozco, Leyre; del Monte-Millán, María; Delgado, Elena; Medina, Miguel

    2012-01-01

    Tideglusib is a GSK-3 inhibitor currently in phase II clinical trials for the treatment of Alzheimer disease and progressive supranuclear palsy. Sustained oral administration of the compound to a variety of animal models decreases Tau hyperphosphorylation, lowers brain amyloid plaque load, improves learning and memory, and prevents neuronal loss. We report here that tideglusib inhibits GSK-3β irreversibly, as demonstrated by the lack of recovery in enzyme function after the unbound drug has been removed from the reaction medium and the fact that its dissociation rate constant is non-significantly different from zero. Such irreversibility may explain the non-competitive inhibition pattern with respect to ATP shown by tideglusib and perhaps other structurally related compounds. The replacement of Cys-199 by an Ala residue in the enzyme seems to increase the dissociation rate, although the drug retains its inhibitory activity with decreased potency and long residence time. In addition, tideglusib failed to inhibit a series of kinases that contain a Cys homologous to Cys-199 in their active site, suggesting that its inhibition of GSK-3β obeys to a specific mechanism and is not a consequence of nonspecific reactivity. Results obtained with [(35)S]tideglusib do not support unequivocally the existence of a covalent bond between the drug and GSK-3β. The irreversibility of the inhibition and the very low protein turnover rate observed for the enzyme are particularly relevant from a pharmacological perspective and could have significant implications on its therapeutic potential.

  6. Irreversibility of mitotic exit is the consequence of systems level feedback

    PubMed Central

    López-Avilés, Sandra; Kapuy, Orsolya; Novák, Béla; Uhlmann, Frank

    2009-01-01

    The eukaryotic cell cycle comprises an ordered series of events, orchestrated by the activity of cyclin-dependent kinases (Cdks), leading from chromosome replication during S-phase to their segregation in mitosis. The unidirectionality of cell cycle transitions is fundamental for successful completion of this cycle. It is thought that irrevocable proteolytic degradation of key cell cycle regulators makes cell cycle transitions irreversible, thereby enforcing directionality1-3. Here, we have experimentally examined the contribution of cyclin proteolysis to the irreversibility of mitotic exit, the transition from high mitotic Cdk activity back to low activity in G1. We show that forced cyclin destruction in mitotic budding yeast cells efficiently drives mitotic exit events. However, these remain reversible after termination of cyclin proteolysis, with recovery of the mitotic state and cyclin levels. Mitotic exit becomes irreversible only after longer periods of cyclin degradation, due to activation of a double-negative feedback loop involving the Cdk inhibitor Sic1 (refs 4​,​5). Quantitative modelling suggests that feedback is required to maintain low Cdk activity and to prevent cyclin resynthesis. Our findings demonstrate that unidirectionality of mitotic exit is not the consequence of proteolysis but of systems level feedback required to maintain the cell cycle in a new stable state. PMID:19387440

  7. Novel Selective and Irreversible Mosquito Acetylcholinesterase Inhibitors for Controlling Malaria and Other Mosquito-Borne Diseases

    NASA Astrophysics Data System (ADS)

    Dou, Dengfeng; Park, Jewn Giew; Rana, Sandeep; Madden, Benjamin J.; Jiang, Haobo; Pang, Yuan-Ping

    2013-01-01

    We reported previously that insect acetylcholinesterases (AChEs) could be selectively and irreversibly inhibited by methanethiosulfonates presumably through conjugation to an insect-specific cysteine in these enzymes. However, no direct proof for the conjugation has been published to date, and doubts remain about whether such cysteine-targeting inhibitors have desirable kinetic properties for insecticide use. Here we report mass spectrometric proof of the conjugation and new chemicals that irreversibly inhibited African malaria mosquito AChE with bimolecular inhibition rate constants (kinact/KI) of 3,604-458,597 M-1sec-1 but spared human AChE. In comparison, the insecticide paraoxon irreversibly inhibited mosquito and human AChEs with kinact/KI values of 1,915 and 1,507 M-1sec-1, respectively, under the same assay conditions. These results further support our hypothesis that the insect-specific AChE cysteine is a unique and unexplored target to develop new insecticides with reduced insecticide resistance and low toxicity to mammals, fish, and birds for the control of mosquito-borne diseases.

  8. Understanding Irreversible Degradation of Nb3Sn Wires with Fundamental Fracture Mechanics

    SciTech Connect

    Zhai, Yuhu; Calzolaio, Ciro; Senatore, Carmine

    2014-08-01

    Irreversible performance degradation of advanced Nb3Sn superconducting wires subjected to transverse or axial mechanical loading is a critical issue for the design of large-scale fusion and accelerator magnets such as ITER and LHC. Recent SULTAN tests indicate that most cable-in-conduit conductors for ITER coils made of Nb3Sn wires processed by various fabrication techniques show similar performance degradation under cyclic loading. The irreversible degradation due to filament fracture and local strain accumulation in Nb3Sn wires cannot be described by the existing strand scaling law. Fracture mechanic modeling combined with X-ray diffraction imaging of filament micro-crack formation inside the wires under mechanical loading may reveal exciting insights to the wire degradation mechanisms. We apply fundamental fracture mechanics with a singularity approach to study influence of wire filament microstructure of initial void size and distribution to local stress concentration and potential crack propagation. We report impact of the scale and density of the void structure on stress concentration in the composite wire materials for crack initiation. These initial defects result in an irreversible degradation of the critical current beyond certain applied stress. We also discuss options to minimize stress concentration in the design of the material microstructure for enhanced wire performance for future applications.

  9. Selection and constraint underlie irreversibility of tooth loss in cypriniform fishes

    PubMed Central

    Aigler, Sharon R.; Jandzik, David; Hatta, Kohei; Uesugi, Kentaro; Stock, David W.

    2014-01-01

    The apparent irreversibility of the loss of complex traits in evolution (Dollo’s Law) has been explained either by constraints on generating the lost traits or the complexity of selection required for their return. Distinguishing between these explanations is challenging, however, and little is known about the specific nature of potential constraints. We investigated the mechanisms underlying the irreversibility of trait loss using reduction of dentition in cypriniform fishes, a lineage that includes the zebrafish (Danio rerio) as a model. Teeth were lost from the mouth and upper pharynx in this group at least 50 million y ago and retained only in the lower pharynx. We identified regional loss of expression of the Ectodysplasin (Eda) signaling ligand as a likely cause of dentition reduction. In addition, we found that overexpression of this gene in the zebrafish is sufficient to restore teeth to the upper pharynx but not to the mouth. Because both regions are competent to respond to Eda signaling with transcriptional output, the likely constraint on the reappearance of oral teeth is the alteration of multiple genetic pathways required for tooth development. The upper pharyngeal teeth are fully formed, but do not exhibit the ancestral relationship to other pharyngeal structures, suggesting that they would not be favored by selection. Our results illustrate an underlying commonality between constraint and selection as explanations for the irreversibility of trait loss; multiple genetic changes would be required to restore teeth themselves to the oral region and optimally functioning ones to the upper pharynx. PMID:24821783

  10. Model for an irreversible bias current in the superconducting qubit measurement process

    SciTech Connect

    Hutchinson, G. D.; Williams, D. A.; Holmes, C. A.; Stace, T. M.; Spiller, T. P.; Barrett, S. D.; Milburn, G. J.; Hasko, D. G.

    2006-12-15

    The superconducting charge-phase ''quantronium'' qubit is considered in order to develop a model for the measurement process used in the experiment of Vion et al. [Science 296, 886 (2002)]. For this model we propose a method for including the bias current in the readout process in a fundamentally irreversible way, which to first order is approximated by the Josephson junction tilted-washboard potential phenomenology. The decohering bias current is introduced in the form of a Lindblad operator and the Wigner function for the current-biased readout Josephson junction is derived and analyzed. During the readout current pulse used in the quantronium experiment we find that the coherence of the qubit initially prepared in a symmetric superposition state is lost at a time of 0.2 ns after the bias current pulse has been applied, a time scale that is much shorter than the experimental readout time. Additionally we look at the effect of Johnson-Nyquist noise with zero mean from the current source during the qubit manipulation and show that the decoherence due to the irreversible bias current description is an order of magnitude smaller than that found through adding noise to the reversible tilted-washboard potential model. Our irreversible bias current model is also applicable to persistent-current-based qubits where the state is measured according to its flux via a small-inductance direct-current superconducting quantum interference device.

  11. Irreversibility behavior in Ag-sheathed Bi-based superconducting wires

    SciTech Connect

    Dou, S.X.; Liu, H.K.; Guo, Y.C.; Wang, J.; Jin, X.J.; Hu, Q.Y.; Shi, D.L.; Salem-Sugui, S.; Wang, Z.

    1992-04-01

    Irreversibility lines for Ag/(Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y}(2223) wires prepared through a phase formation- decomposition-recovery (PFDR) process and normal annealing process were determined using both AC susceptibility measurements under DC fields and magnetisation measurements. It was found that flux pinning was enhanced in the PFDR processed samples over the normal processed samples, in particular at temperature above 77 K. The PFDR process results in high mass density, grain alignment, uniform distribution of impurity precipitates and high density of defects. The irreversibility temperatures scaled with the applied field according to H{sup 1/3}, which is in contrast to H{sup 2/3} law for YBa{sub 2}Cu{sub 3}O{sub 7-x} and conventional superconductors. The irreversibility lines for PFDR processed tapes showed a crossover with those for normal processed tapes at temperature below {Tc} of the (Bi,Pb){sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} (2212), suggesting that at temperature above {Tc} of the 2212 phase, the 2212 as nonsuperconducting region, may serve as effective pinning sites for fluxoids.

  12. Evidence for Irreversible Inhibition of Glycogen Synthase Kinase-3β by Tideglusib*

    PubMed Central

    Domínguez, Juan Manuel; Fuertes, Ana; Orozco, Leyre; del Monte-Millán, María; Delgado, Elena; Medina, Miguel

    2012-01-01

    Tideglusib is a GSK-3 inhibitor currently in phase II clinical trials for the treatment of Alzheimer disease and progressive supranuclear palsy. Sustained oral administration of the compound to a variety of animal models decreases Tau hyperphosphorylation, lowers brain amyloid plaque load, improves learning and memory, and prevents neuronal loss. We report here that tideglusib inhibits GSK-3β irreversibly, as demonstrated by the lack of recovery in enzyme function after the unbound drug has been removed from the reaction medium and the fact that its dissociation rate constant is non-significantly different from zero. Such irreversibility may explain the non-competitive inhibition pattern with respect to ATP shown by tideglusib and perhaps other structurally related compounds. The replacement of Cys-199 by an Ala residue in the enzyme seems to increase the dissociation rate, although the drug retains its inhibitory activity with decreased potency and long residence time. In addition, tideglusib failed to inhibit a series of kinases that contain a Cys homologous to Cys-199 in their active site, suggesting that its inhibition of GSK-3β obeys to a specific mechanism and is not a consequence of nonspecific reactivity. Results obtained with [35S]tideglusib do not support unequivocally the existence of a covalent bond between the drug and GSK-3β. The irreversibility of the inhibition and the very low protein turnover rate observed for the enzyme are particularly relevant from a pharmacological perspective and could have significant implications on its therapeutic potential. PMID:22102280

  13. Ultraviolet-induced irreversible tensile actuation of diacetylene/nylon microfibers

    NASA Astrophysics Data System (ADS)

    Chun, Kyoung-Yong; Choi, Changsoon; Baughman, Ray H.; Kim, Seon Jeong

    2016-07-01

    Photomechanically irreversible tensile-actuated diacetylene-embedding nylon 6/6 microfibers were investigated. 10,12-pentacosadiynoic acid (PCDA) monomer, which have conventionally provided a visual color change by temperature and photo-driven stimuli, was embedded in nylon 6/6 microfibers by wet spinning. By ultraviolet (UV) (254 nm) exposure, we observed irreversible tensile actuation (contraction) of linear (untwisted) and helical (twisted) structural microfibers. The tensile contraction of twisted nylon 6/6-PCDA microfiber containing10 mM PCDA was reached to ∼2% at 60 °C. Such irreversible tensile contraction can be promoted by volume contraction of PCDA monomers during UV exposure along with irregular structural deformation containing gauche conformation with increasing temperature. The kinetics of tensile contraction with temperature and time were shown by the Arrhenius plots. The activation energies were 34.3–35.7 kJ mol‑1 as increasing the concentration of PCDA, implies that the nylon 6/6-PCDA microfibers could be applied to show time-temperature integrated device.

  14. Irreversibilities and efficiency at maximum power of heat engines: the illustrative case of a thermoelectric generator.

    PubMed

    Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph

    2012-03-01

    Energy conversion efficiency at maximum output power, which embodies the essential characteristics of heat engines, is the main focus of the present work. The so-called Curzon and Ahlborn efficiency η(CA) is commonly believed to be an absolute reference for real heat engines; however, a different but general expression for the case of stochastic heat engines, η(SS), was recently found and then extended to low-dissipation engines. The discrepancy between η(CA) and η(SS) is here analyzed considering different irreversibility sources of heat engines, of both internal and external types. To this end, we choose a thermoelectric generator operating in the strong-coupling regime as a physical system to qualitatively and quantitatively study the impact of the nature of irreversibility on the efficiency at maximum output power. In the limit of pure external dissipation, we obtain η(CA), while η(SS) corresponds to the case of pure internal dissipation. A continuous transition between from one extreme to the other, which may be operated by tuning the different sources of irreversibility, also is evidenced. PMID:22587047

  15. Ultraviolet-induced irreversible tensile actuation of diacetylene/nylon microfibers

    NASA Astrophysics Data System (ADS)

    Chun, Kyoung-Yong; Choi, Changsoon; Baughman, Ray H.; Kim, Seon Jeong

    2016-07-01

    Photomechanically irreversible tensile-actuated diacetylene-embedding nylon 6/6 microfibers were investigated. 10,12-pentacosadiynoic acid (PCDA) monomer, which have conventionally provided a visual color change by temperature and photo-driven stimuli, was embedded in nylon 6/6 microfibers by wet spinning. By ultraviolet (UV) (254 nm) exposure, we observed irreversible tensile actuation (contraction) of linear (untwisted) and helical (twisted) structural microfibers. The tensile contraction of twisted nylon 6/6-PCDA microfiber containing10 mM PCDA was reached to ˜2% at 60 °C. Such irreversible tensile contraction can be promoted by volume contraction of PCDA monomers during UV exposure along with irregular structural deformation containing gauche conformation with increasing temperature. The kinetics of tensile contraction with temperature and time were shown by the Arrhenius plots. The activation energies were 34.3-35.7 kJ mol-1 as increasing the concentration of PCDA, implies that the nylon 6/6-PCDA microfibers could be applied to show time-temperature integrated device.

  16. Contaminant-induced irreversible changes in properties of the soil-vadose-aquifer zone: an overview.

    PubMed

    Yaron, Bruno; Dror, Ishai; Berkowitz, Brian

    2008-04-01

    Most studies on contaminant interactions with the subsurface environment focus on contaminant transport, retention and persistence, and on potential remediation of polluted soils, vadose zones and aquifers. Changes in the soil-vadose-aquifer zone (SVAZ) matrix and properties, caused by human activities, are thus usually considered to be deviations from a normal geochemical environment, which will disappear by natural processes or by specific remediation procedures. However, contaminants may also cause, under specific conditions, irreversible changes in SVAZ properties. In this critical overview, we discuss a different aspect of contaminant-SVAZ interactions: irreversible changes in natural SVAZ properties as a result of anthropogenically-induced chemical contamination. We survey selected research results that illustrate various aspects of such phenomena, in soils, aquifers and the vadose zone. Grouping contaminants according to major and trace elements, we observe that major elements can irreversibly affect water transmission and other physical and chemical properties of the SVAZ, mainly in the liquid phase, while trace elements affect mostly the solid phase matrix.

  17. Thickness dependence of the irreversibility line in YBa sub 2 Cu sub 3 O sub 7 minus x thin films

    SciTech Connect

    Civale, L.; Worthington, T.K.; Gupta, A. )

    1991-03-01

    We report a determination of the irreversibility line in the field-temperature plane of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} films measured by ac susceptibility. For films thicker than {similar to}1000 A, {ital H}{sub irr} is similar to that observed in single crystals even though the critical current in the films is orders of magnitude larger. However, for films thinner than 1000 A, the irreversibility line is observed to shift to lower temperatures. This suppression is discussed in terms of various models for the irreversibility line.

  18. Irreversible deformation and the superplasticity of a TN-1 alloy during thermal cycling through the martensitic transformations ranges under loading

    NASA Astrophysics Data System (ADS)

    Andronov, I. N.; Ryabkov, Yu. I.; Bogdanov, N. P.; Severova, N. A.; Danilov, A. N.; Churilina, I. V.

    2015-10-01

    The influence of the thermal cycling conditions on the thermal-cycling creep of a TN-1 alloy and the related irreversible deformations is studied. The conditions under which an anomalous increase in the irreversible deformations begins are determined. The structural mechanism of the irreversible deformations of an equiatomic alloy is shown to be analogous to the structural mechanism of metal creep at high temperatures: it predominantly has a dislocation character. It is proposed to use the effect of anomalous increase in the deformation of materials with reversible martensitic transformations for forming parts made of these materials at low temperatures.

  19. Efficiency at maximum power output of linear irreversible Carnot-like heat engines.

    PubMed

    Wang, Yang; Tu, Z C

    2012-01-01

    The efficiency at maximum power output of linear irreversible Carnot-like heat engines is investigated based on the assumption that the rate of irreversible entropy production of the working substance in each "isothermal" process is a quadratic form of the heat exchange rate between the working substance and the reservoir. It is found that the maximum power output corresponds to minimizing the irreversible entropy production in two isothermal processes of the Carnot-like cycle, and that the efficiency at maximum power output has the form η(mP)=η(C)/(2-γη(C)), where η(C) is the Carnot efficiency, while γ depends on the heat transfer coefficients between the working substance and two reservoirs. The value of η(mP) is bounded between η(-)≡η(C)/2 and η(+)≡η(C)/(2-η(C)). These results are consistent with those obtained by Chen and Yan [J. Chem. Phys. 90, 3740 (1989)] based on the endoreversible assumption, those obtained by Esposito et al. [Phys. Rev. Lett. 105, 150603 (2010)] based on the low-dissipation assumption, and those obtained by Schmiedl and Seifert [Europhys. Lett. 81, 20003 (2008)] for stochastic heat engines which in fact also satisfy the low-dissipation assumption. Additionally, we find that the endoreversible assumption happens to hold for Carnot-like heat engines operating at the maximum power output based on our fundamental assumption, and that the Carnot-like heat engines that we focused on do not strictly satisfy the low-dissipation assumption, which implies that the low-dissipation assumption or our fundamental assumption is a sufficient but non-necessary condition for the validity of η(mP)=η(C)/(2-γη(C)) as well as the existence of two bounds, η(-)≡η(C)/2 and η(+)≡η(C)/(2-η(C)).

  20. Mechanisms of physically irreversible fouling during surface water microfiltration and mitigation by aluminum electroflotation pretreatment.

    PubMed

    Gamage, Neranga P; Chellam, Shankararaman

    2014-01-21

    A modified poly(vinylidene fluoride) membrane was used to directly microfilter untreated Lake Houston water, which was then regenerated by surface washing and hydraulic backwashing, a process that was cycled five times. The source water was also electrochemically precoagulated using aluminum and microfiltered, and the membrane was physically regenerated for five cycles. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) were used to characterize foulants on membrane surfaces and rigorously deduce their contributions to physically irreversible fouling after cycles 1 and 5. Hydrophobic molecules primarily appeared to initiate fouling during microfiltration of untreated raw water because O-H/N-H bands were attenuated while C-H bands remained relatively unchanged in FTIR-spectra of membrane surfaces after only one cycle. However, O-H/N-H and symmetric and asymmetric C(═ O)O(-) stretching bands significantly intensified with continued filtration/regeneration of untreated water, showing the importance of hydrophilic molecules and the role of complexation, respectively, to longer term irreversible fouling. Distinct C-H bands were detected in floated flocs after electrolysis, suggesting the sorption and subsequent removal of a substantial portion of the hydrophobic moieties present in Lake Houston water during pretreatment. Consequently, hydrophilic compounds appeared to contribute more to irreversible fouling in pretreated waters throughout the course of filtration as evidenced by significantly more intense O-H bands (compared with C-H bands) on the membrane surface after cycles 1 and 5. Therefore, electroflotation pretreatment reduced accumulation of hydrophobic foulants but simultaneously increased complexation of hydrophilic foulant molecules along with any carried-over aluminum hydroxide precipitates evidenced by increasing Al and O concentrations via XPS and intense C(═ O)O(-) stretching

  1. Nanostructure and irreversible colloidal behavior of Ca(OH)2: implications in cultural heritage conservation.

    PubMed

    Rodriguez-Navarro, C; Ruiz-Agudo, E; Ortega-Huertas, M; Hansen, E

    2005-11-22

    Although Ca(OH)2 is one of the oldest art and building material used by mankind, little is known about its nanostructural and colloidal characteristics that play a crucial role in its ultimate performance as a binder in lime mortars and plasters. In particular, it is unknown why hydrated lime putty behaves as an irreversible colloid once dried. Such effect dramatically affects the reactivity and rheology of hydrated lime dispersions. Here we show that the irreversible colloidal behavior of Ca(OH)2 dispersions is the result of an oriented aggregation mechanism triggered by drying. Kinetic stability and particle size distribution analysis of oven-dried slaked lime or commercial dry hydrate dispersions exhibit a significant increase in settling speed and particle (cluster) size in comparison to slaked lime putty that has never been dried. Drying-related particle aggregation also leads to a significant reduction in surface area. Electron microscopy analyses show porous, randomly oriented, micron-sized clusters that are dominant in the dispersions both before and after drying. However, oriented aggregation of the primary Ca(OH)2 nanocrystals (approximately 60 nm in size) is also observed. Oriented aggregation occurs both before and during drying, and although limited before drying, it is extensive during drying. Nanocrystals self-assemble in a crystallographically oriented manner either along the 100 or equivalent 110 directions, or along the Ca(OH)2 basal planes, i.e., along [001]. While random aggregation appears to be reversible, oriented aggregation is not. The strong coherent bonding among oriented nanoparticles prevents disaggregation upon redispersion in water. The observed irreversible colloidal behavior associated with drying of Ca(OH)2 dispersions has important implications in heritage conservation, particularly considering that nowadays hydrated lime is often the preferred alternative to portland cement in architectural heritage conservation. Finally, our

  2. Mechanisms of physically irreversible fouling during surface water microfiltration and mitigation by aluminum electroflotation pretreatment.

    PubMed

    Gamage, Neranga P; Chellam, Shankararaman

    2014-01-21

    A modified poly(vinylidene fluoride) membrane was used to directly microfilter untreated Lake Houston water, which was then regenerated by surface washing and hydraulic backwashing, a process that was cycled five times. The source water was also electrochemically precoagulated using aluminum and microfiltered, and the membrane was physically regenerated for five cycles. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) were used to characterize foulants on membrane surfaces and rigorously deduce their contributions to physically irreversible fouling after cycles 1 and 5. Hydrophobic molecules primarily appeared to initiate fouling during microfiltration of untreated raw water because O-H/N-H bands were attenuated while C-H bands remained relatively unchanged in FTIR-spectra of membrane surfaces after only one cycle. However, O-H/N-H and symmetric and asymmetric C(═ O)O(-) stretching bands significantly intensified with continued filtration/regeneration of untreated water, showing the importance of hydrophilic molecules and the role of complexation, respectively, to longer term irreversible fouling. Distinct C-H bands were detected in floated flocs after electrolysis, suggesting the sorption and subsequent removal of a substantial portion of the hydrophobic moieties present in Lake Houston water during pretreatment. Consequently, hydrophilic compounds appeared to contribute more to irreversible fouling in pretreated waters throughout the course of filtration as evidenced by significantly more intense O-H bands (compared with C-H bands) on the membrane surface after cycles 1 and 5. Therefore, electroflotation pretreatment reduced accumulation of hydrophobic foulants but simultaneously increased complexation of hydrophilic foulant molecules along with any carried-over aluminum hydroxide precipitates evidenced by increasing Al and O concentrations via XPS and intense C(═ O)O(-) stretching

  3. Template-assisted three-dimensional nanolithography via geometrically irreversible processing.

    PubMed

    Yu, Xindi; Zhang, Huigang; Oliverio, John K; Braun, Paul V

    2009-12-01

    An innovative and versatile nanofabrication technique based on template assisted three-dimensional (3D) nanolithography is presented that takes advantage of the irreversibility of conformal growth and conformal etching at locations with negative surface curvatures in 3D templates. Using colloidal crystals as templates, nanoring particles are generated with quantity much higher than conventional methods. Relying on the same principle, metallodielectric photonic crystals with discrete metal elements are fabricated that show strong absorption in the near-IR and transmission at longer wavelengths.

  4. Analysis of a quantum irreversible Otto cycle with exergetic sustainable index

    NASA Astrophysics Data System (ADS)

    Dalkıran, Alper; Açıkkalp, Emin; Caner, Necmettin

    2016-07-01

    In this study, exergetic sustainability index is applied to quantum irreversible Otto cycle with -1/2 spin system. Exergetic sustainability index in a quantum engine is used first time. This index is the ratio of exergy output (work output for a thermal engine) to total exergetic losses. It gives an opportunity to evaluate for all thermodynamic losses in the system, that is why, it is an important index. In addition, some thermodynamic parameters (work output, exergy destruction, first and second law efficiencies) are considered and their relationships between the exergetic sustainability index are determined.

  5. Giant flux creep through the surface barriers and the irreversibility line in high-{Tc} superconductors

    SciTech Connect

    Burlachkov, L.; Geshkenbein, V.B. ||; Koshelev, A.E. |; Larkin, A.I. |; Vinokur, V.M.

    1994-05-01

    Magnetic flux relaxation over the surface barrier in high temperature superconductors are investigated Vortex dynamics controlled by the penetration both of pancake vortices and vortex lines are discussed. The penetration field H{sub p} for pancakes decay is exponentially with temperature. The size of the magnetization loop is determined by the decay of H{sub p} during the process of relaxation, but its shape remains unchanged. The irreversibility line associated with the pancake penetration is given by H{sub irr} {proportional_to} exp(- 2T/T{sub o}), and may lie both above and below the melting line.

  6. Irreversible adsorption of gold nanospheres on fiber optical tapers and microspheres

    PubMed Central

    Yi, Jihaeng; Jao, Chih-Yu; Kandas, Ishac L. N.; Liu, Bo; Xu, Yong; Robinson, Hans D.

    2012-01-01

    We study the adsorption of gold nanospheres onto cylindrical and spherical glass surfaces from quiescent particle suspensions. The surfaces consist of tapers and microspheres fabricated from optical fibers and were coated with a polycation, enabling irreversible nanosphere adsorption. Our results fit well with theory, which predicts that particle adsorption rates depend strongly on surface geometry and can exceed the planar surface deposition rate by over two orders of magnitude when particle diffusion length is large compared to surface curvature. This is particularly important for plasmonic sensors and other devices fabricated by depositing nanoparticles from suspensions onto surfaces with non-trivial geometries. PMID:22550356

  7. Concentration effects on the rates of irreversible diffusion-influenced reactions

    SciTech Connect

    Kim, Minjung; Lee, Sangyoub; Kim, Ji-Hyun

    2014-08-28

    We formulate a new theory of the effects of like-particle interactions on the irreversible diffusion-influenced bimolecular reactions of the type A + B → P + B by considering the evolution equation of the triplet ABB number density field explicitly. The solution to the evolution equation is aided by a recently proposed method for solving the Fredholm integral equation of the second kind. We evaluate the theory by comparing its predictions with the results of extensive computer simulations. The present theory provides a reasonable explanation of the simulation results.

  8. Irreversible pulmonary hypertension associated with Troglostrongylus brevior infection in a kitten.

    PubMed

    Crisi, Paolo E; Traversa, Donato; Di Cesare, Angela; Luciani, Alessia; Civitella, Carla; Santori, Domenico; Boari, Andrea

    2015-10-01

    A four month-old kitten was referred at the Veterinary Teaching Hospital of Teramo, Italy. Physical examination, echocardiography, thoracic radiography, copromicroscopy and biomolecular assays led to a diagnosis of severe parasitic bronchopneumonia by Troglostrongylus brevior complicated by pulmonary hypertension. A single administration of a spot on solution containing imidacloprid 10%/moxidectin 1% was effective in stopping larval shedding but clinical, radiographic and echocardiographic signs of bronchopneumonia and pulmonary hypertension still persisted after further follow-ups.While cases of pulmonary hypertension are known in infections by Aelurostrongylus abstrusus, this is the first report of irreversible pulmonary hypertension in a kitten with troglostrongylosis. PMID:26412548

  9. Nucleation of a new phase on a surface that is changing irreversibly with time.

    PubMed

    Sear, Richard P

    2014-02-01

    Nucleation of a new phase almost always starts at a surface. This surface is almost always assumed not to change with time. However, surfaces can roughen, partially dissolve, and change chemically with time. Each of these irreversible changes will change the nucleation rate at the surface, resulting in a time-dependent nucleation rate. Here we use a simple model to show that partial surface dissolution can qualitatively change the nucleation process in a way that is testable in experiment. The changing surface means that the nucleation rate is increasing with time. There is an initial period during which no nucleation occurs, followed by relatively rapid nucleation. PMID:25353480

  10. Irreversible thermochromic behavior in gold and silver nanorod/polymeric ionic liquid nanocomposite films.

    PubMed

    Tollan, Christopher M; Marcilla, Rebeca; Pomposo, Jose A; Rodriguez, Javier; Aizpurua, Javier; Molina, Jon; Mecerreyes, David

    2009-02-01

    The novel application of gold and silver nanorods as irreversible thermochromic dyes in polymeric ionic liquid (PIL) nanocomposites is proposed here. These materials have been synthesized by anion exchange of an imidazolium-based PIL in a solution that also contained gold nanorods. This resulted in the entrapment of the nanoobjects within a solid polymer precipitate. In this article, the effect of the temperature was studied in relation to the change of shape and, consequently, color of the gold or silver nanorods within the films. For the nanocomposites studied here, a maximum of two visual thermochromic transitions was observed for gold nanorods and up to three transitions were observed for silver nanorods.

  11. Optimal allocation of thermodynamic irreversibility for the integrated design of propulsion and thermal management systems

    NASA Astrophysics Data System (ADS)

    Maser, Adam Charles

    work losses over the time history of the mission. The characterization of the thermodynamic irreversibility distribution helps give the propulsion systems designer an absolute and consistent view of the tradeoffs associated with the design of the entire integrated system. Consequently, this leads directly to the question of the proper allocation of irreversibility across each of the components. The process of searching for the most favorable allocation of this irreversibility is the central theme of the research and must take into account production cost and vehicle mission performance. The production cost element is accomplished by including an engine component weight and cost prediction capability within the system model. The vehicle mission performance is obtained by directly linking the propulsion and thermal management model to a vehicle performance model and flying it through a mission profile. A canonical propulsion and thermal management systems architecture is then presented to experimentally test each element of the methodology separately: first the integrated modeling and simulation, then the irreversibility, cost, and mission performance considerations, and then finally the proper technique to perform the optimal allocation. A goal of this research is the description of the optimal allocation of system irreversibility to enable an engine cycle design with improved performance and cost at the vehicle-level. To do this, a numerical optimization was first used to minimize system-level production and operating costs by fixing the performance requirements and identifying the best settings for all of the design variables. There are two major drawbacks to this approach: It does not allow the designer to directly trade off the performance requirements and it does not allow the individual component losses to directly factor into the optimization. An irreversibility allocation approach based on the economic concept of resource allocation is then compared to the

  12. Percutaneous Irreversible Electroporation of Unresectable Hilar Cholangiocarcinoma (Klatskin Tumor): A Case Report.

    PubMed

    Melenhorst, Marleen C A M; Scheffer, Hester J; Vroomen, Laurien G P H; Kazemier, Geert; van den Tol, M Petrousjka; Meijerink, Martijn R

    2016-01-01

    Irreversible electroporation (IRE) is a novel image-guided ablation technique that is rapidly gaining popularity in the treatment of malignant tumors located near large vessels or bile ducts. The presence of metal objects in the ablation zone, such as Wallstents, is generally considered a contraindication for IRE, because tissue heating due to power conduction may lead to thermal complications. This report describes a 66-year-old female with a Bismuth-Corlette stage IV unresectable cholangiocarcinoma with a metallic Wallstent in the common bile duct, who was safely treated with percutaneous IRE with no signs for relapse 1 year after the procedure.

  13. Irreversible, direct bonding of nanoporous polymer membranes to PDMS or glass microdevices.

    PubMed

    Aran, Kiana; Sasso, Lawrence A; Kamdar, Neal; Zahn, Jeffrey D

    2010-03-01

    A method for integrating porous polymer membranes such as polycarbonate, polyethersulfone and polyethylene terephthalate to microfluidic devices is described. The use of 3-aminopropyltriethoxysilane as a chemical crosslinking agent was extended to integrate membranes with PDMS and glass microfluidic channels. A strong, irreversible bond between the membranes and microfluidic structure was achieved. The bonding strength in the APTES treated devices was significantly greater than in devices fabricated using either a PDMS "glue" or two-part epoxy bonding method. Evaluation of a filtering microdevice and the pore structure via SEM indicates the APTES conjugation does not significantly alter the membrane transport function and pore morphology.

  14. Irreversible shear-induced vitrification of droplets into elastic nanoemulsions by extreme rupturing

    SciTech Connect

    Wilking, James N.; Mason, Thomas G.

    2007-04-15

    Many materials weaken through fracturing when subjected to extreme stresses. By contrast, we show that breaking down repulsive bits of matter dispersed in a viscous liquid can cause a dramatic and irreversible increase in the dispersion's elasticity. Anionically stabilized microscale emulsions subjected to a history of high-pressure microfluidic flow can develop an unusually large elastic modulus as droplets are ruptured to the nanoscale, yielding 'nanonaise'. As the droplet size approaches the Debye screening length, the nanoemulsion vitrifies. Consequently, the onset of elasticity for disordered uniform nanoemulsions can occur at droplet volume fractions far below maximal random jamming of spheres.

  15. New Method for Evaluating Irreversible Adsorption and Stationary Phase Bleed in Gas Chromatographic Capillary Columns

    SciTech Connect

    Wright, Bob W.; Wright, Cherylyn W.

    2012-10-26

    A novel method for the evaluation of gas chromatographic (GC) column inertness has been developed using a tandem GC approach. Typically column inertness is measured by analyte peak shape evaluation. In general, silica, glass, and metal surfaces are chemically reactive and can cause analyte adsorption, which typically is observed as chromatographic peak tailing. Adsorption processes produce broad, short chromatographic peaks that confound peak area determinations because a significant portion can reside in the noise. In addition, chromatographic surfaces and stationary phases can irreversibly adsorb certain analytes without obvious degradation of peak shape. The inertness measurements described in this work specifically determine the degree of irreversible adsorption behavior of specific target compounds at levels ranging from approximately 50 picograms to 1 nanogram on selected gas chromatographic columns. Chromatographic columns with 5% phenylmethylsiloxane, polyethylene glycol (wax), trifluoropropylsiloxane, and 78% cyanopropylsiloxane stationary phases were evaluated with a variety of phosphorus- and sulfur- containing compounds selected as test compounds due to their ease of adsorption and importance in trace analytical detection. In addition, the method was shown effective for characterizing column bleed.

  16. Theoretical characterisation of irreversible and reversible hydrogen storage reactions on Ni-doped C60 fullerene

    NASA Astrophysics Data System (ADS)

    Shalabi, A. S.; El Mahdy, A. M.; Soliman, K. A.; Taha, H. O.

    2014-12-01

    An attempt has been made to characterise the irreversible and reversible hydrogen storage reactions on Ni-doped C60 fullerene by using the state of the art density functional theory calculations. The single Ni atom prefers to bind at the bridge site between two hexagonal rings of C60 fullerene, and can bind up to four hydrogen molecules with average adsorption energies of -0.85, -0.83, -0.58, and -0.31 eV per hydrogen molecule. No evidence for metal clustering in the ideal circumstances and the hydrogen storage capacity is expected to be as large as 8.9 wt%. While the desorption activation barriers of the complexes nH2NiC60 (n = 1, 2) are outside the desirable energy window recommended by the department of energy for practical applications (-0.2 to -0.6 eV), the desorption activation barriers of the complexes nH2NiC60 (n = 3, 4) are inside this window. The irreversible 2H2 + NiC60 and reversible 3H2 + NiC60 interactions are characterised in terms of several theoretical parameters such as: (1) densities of states and projected densities of states, (2) pairwise and non-pairwise additivity, (3) infrared, Raman, and proton magnetic resonance spectra, (4) electrophilicity, and (5) statistical thermodynamic stability.

  17. Magnetic resonance imaging characteristics of nonthermal irreversible electroporation in vegetable tissue.

    PubMed

    Hjouj, Mohammad; Rubinsky, Boris

    2010-07-01

    We introduce and characterize the use of MRI for studying nonthermal irreversible electroporation (NTIRE) in a vegetative tissue model. NTIRE is a new minimally invasive surgical technique for tissue ablation in which microsecond, high electric-field pulses form nanoscale defects in the cell membrane that lead to cell death. Clinical NTIRE sequences were applied to a potato tuber tissue model. The potato is used for NTIRE studies because cell damage is readily visible with optical means through a natural oxidation process of released intracellular enzymes (polyphenol oxidase) and the formation of brown-black melanins. MRI sequences of the treated area were taken at various times before and after NTIRE and compared with photographic images. A comparison was made between T1W, T2W, FLAIR and STIR MRIs of NTIRE and photographic images. Some MRI sequences show changes in areas treated by irreversible electroporation. T1W and FLAIR produce brighter images of the treated areas. In contrast, the signal was lost from the treated area when a suppression technique, STIR, was used. There was similarity between optical photographic images of the treated tissue and MRIs of the same areas. This is the first study to characterize MRI of NTIRE in vegetative tissue. We find that NTIRE produces changes in vegetative tissue that can be imaged by certain MRI sequences. This could make MRI an effective tool to study the fundamentals of NTIRE in nonanimal tissue. PMID:20631997

  18. Ablation of irreversibly rejected renal allograft by embolization with absolute ethanol: a new clinical application.

    PubMed

    Lorenzo, V; Díaz, F; Perez, L; Domínguez, M L; Machado, M; Rodríguez, A; González-Posada, J; Hernández, D; de Bonis, E; Torres, A

    1993-10-01

    Surgical allograft nephrectomy has been the conventional therapy for removing failed kidney allografts when clinical manifestations of graft intolerance appear. However, removal of a transplanted kidney is an extensive surgical procedure. On the other hand, transcatheter vascular embolization (TVE) has proven useful in ablating organs and could be applied to renal transplant ablation. The aim of this study was to present the results of TVE for the treatment of graft intolerance syndrome (GIS) in failed allograft kidneys. Transcatheter vascular embolization was performed in 14 allograft recipients (33 +/- 13 years of age; 10 men and four women) affected by GIS after irreversible kidney allograft failure. Graft intolerance syndrome was diagnosed by fever (93%), hematuria (50%), graft pain (36%), flu-like symptoms (29%), and increased graft size (29%). Absolute ethanol (0.1 mL/kg body weight) was injected in the allograft artery, and in seven patients a stainless steel coil was left in the renal artery following ethanol injection. All patients showed clinical disappearance of the GIS. No major complication occurred, although a postembolization syndrome of pain, fever, hematuria, numbness, and paresthesia of the affected area appeared in 11 of the 14 patients. After 2 to 56 months of follow-up no late complications occurred, with the exception of a graft abscess formation in one patient after 6 months of embolization. Subsequent transplantectomy was uneventful. In conclusion, TVE is a safe and effective method for kidney graft ablation, and it may become an alternative treatment for GIS following irreversible rejection.

  19. Transiently Produced Hypochlorite Is Responsible for the Irreversible Inhibition of Chlorite Dismutase

    PubMed Central

    2014-01-01

    Chlorite dismutases (Clds) are heme b-containing prokaryotic oxidoreductases that catalyze the reduction of chlorite to chloride with the concomitant release of molecular oxygen. Over time, they are irreversibly inactivated. To elucidate the mechanism of inactivation and investigate the role of the postulated intermediate hypochlorite, the pentameric chlorite dismutase of “Candidatus Nitrospira defluvii” (NdCld) and two variants (having the conserved distal arginine 173 exchanged with alanine and lysine) were recombinantly produced in Escherichia coli. Exchange of the distal arginine boosts the extent of irreversible inactivation. In the presence of the hypochlorite traps methionine, monochlorodimedone, and 2-[6-(4-aminophenoxy)-3-oxo-3H-xanthen-9-yl]benzoic acid, the extent of chlorite degradation and release of molecular oxygen is significantly increased, whereas heme bleaching and oxidative modifications of the protein are suppressed. Among other modifications, hypochlorite-mediated formation of chlorinated tyrosines is demonstrated by mass spectrometry. The data obtained were analyzed with respect to the proposed reaction mechanism for chlorite degradation and its dependence on pH. We discuss the role of distal Arg173 by keeping hypochlorite in the reaction sphere for O–O bond formation. PMID:24754261

  20. Irreversible Electroporation of Renal Cell Carcinoma: A First-in-Man Phase I Clinical Study

    SciTech Connect

    Pech, Maciej; Janitzky, Andreas; Wendler, Johann Jacob; Strang, Christof; Blaschke, Simon; Dudeck, Oliver; Ricke, Jens; Liehr, Uwe-Bernd

    2011-02-15

    Purpose: Irreversible electroporation (IRE) is a newly developed nonthermal tissue-ablation technique in which high-voltage electrical pulses of microsecond duration are applied to induce irreversible permeabilisation of the cell membrane, presumably through nanoscale defects in the lipid bilayer, leading to apoptosis. The purpose of this study was to assess the feasibility and safety of ablating renal cell carcinoma (RCC) tissue by IRE. Methods: Six patients scheduled for curative resection of RCC were included. IRE was performed during anaesthesia immediately before the resection with electrographic synchronisation. Central haemodynamics were recorded before and 5 min after electroporation. Five-channel electrocardiography (ECG) was used for detailed analysis of ST waveforms. Blood sampling and 12-lead ECG were performed before, during, and at scheduled intervals after the intervention. Results: Analysis of ST waveforms and axis deviations showed no relevant changes during the entire study period. No changes in central haemodynamics were seen 5 min after IRE. Similarly, haematological, serum biochemical, and ECG variables showed no relevant differences during the investigation period. No changes in cardiac function after IRE therapy were found. One case of supraventricular extrasystole was encountered. Initial histopathologic examination showed no immediate adverse effects of IRE (observation of delayed effects will require a different study design). Conclusion: IRE seems to offer a feasible and safe technique by which to treat patients with kidney tumours and could offer some potential advantages over current thermal ablative techniques.

  1. Irreversible inhibition of human immunodeficiency virus type 1 integrase by dicaffeoylquinic acids.

    PubMed

    Zhu, K; Cordeiro, M L; Atienza, J; Robinson, W E; Chow, S A

    1999-04-01

    Human immunodeficiency virus type 1 (HIV-1) and other retroviruses require integration of a double-stranded DNA copy of the RNA genome into the host cell chromosome for productive infection. The viral enzyme, integrase, catalyzes the integration of retroviral DNA and represents an attractive target for developing antiretroviral agents. We identified several derivatives of dicaffeoylquinic acids (DCQAs) that inhibit HIV-1 replication in tissue culture and catalytic activities of HIV-1 integrase in vitro. The specific step at which DCQAs inhibit the integration in vitro and the mechanism of inhibition were examined in the present study. Titration experiments with different concentrations of HIV-1 integrase or DNA substrate found that the effect of DCQAs was exerted on the enzyme and not the DNA. In addition to HIV-1, DCQAs also inhibited the in vitro activities of MLV integrase and truncated variants of feline immunodeficiency virus integrase, suggesting that these compounds interacted with the central core domain of integrase. The inhibition on retroviral integrases was relatively specific, and DCQAs had no effect on several other DNA-modifying enzymes and phosphoryltransferases. Kinetic analysis and dialysis experiments showed that the inhibition of integrase by DCQAs was irreversible. The inhibition did not require the presence of a divalent cation and was unaffected by preassembling integrase onto viral DNA. The results suggest that the irreversible inhibition by DCQAs on integrase is directed toward conserved amino acid residues in the central core domain during catalysis.

  2. Irreversibly increased nitrogen fixation in Trichodesmium experimentally adapted to elevated carbon dioxide

    PubMed Central

    Hutchins, David A.; Walworth, Nathan G.; Webb, Eric A.; Saito, Mak A.; Moran, Dawn; McIlvin, Matthew R.; Gale, Jasmine; Fu, Fei-Xue

    2015-01-01

    Nitrogen fixation rates of the globally distributed, biogeochemically important marine cyanobacterium Trichodesmium increase under high carbon dioxide (CO2) levels in short-term studies due to physiological plasticity. However, its long-term adaptive responses to ongoing anthropogenic CO2 increases are unknown. Here we show that experimental evolution under extended selection at projected future elevated CO2 levels results in irreversible, large increases in nitrogen fixation and growth rates, even after being moved back to lower present day CO2 levels for hundreds of generations. This represents an unprecedented microbial evolutionary response, as reproductive fitness increases acquired in the selection environment are maintained after returning to the ancestral environment. Constitutive rate increases are accompanied by irreversible shifts in diel nitrogen fixation patterns, and increased activity of a potentially regulatory DNA methyltransferase enzyme. High CO2-selected cell lines also exhibit increased phosphorus-limited growth rates, suggesting a potential advantage for this keystone organism in a more nutrient-limited, acidified future ocean. PMID:26327191

  3. Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures

    SciTech Connect

    Seoung, Donghoon; Cynn, Hyunchae; Park, Changyong; Choi, Kwang -Yong; Blom, Douglas A.; Evans, William J.; Kao, Chi -Chang; Vogt, Thomas; Lee, Yongjae

    2014-09-01

    Pressure drastically alters the chemical and physical properties of materials and allows structural phase transitions and chemical reactions to occur that defy much of our understanding gained under ambient conditions. Particularly exciting is the high-pressure chemistry of xenon, which is known to react with hydrogen and ice at high pressures and form stable compounds. Here, we show that Ag16Al16Si24O8·16H2O (Ag-natrolite) irreversibly inserts xenon into its micropores at 1.7 GPa and 250 °C, while Ag+ is reduced to metallic Ag and possibly oxidized to Ag2+. In contrast to krypton, xenon is retained within the pores of this zeolite after pressure release and requires heat to desorb. This irreversible insertion and trapping of xenon in Ag-natrolite under moderate conditions sheds new light on chemical reactions that could account for the xenon deficiency relative to argon observed in terrestrial and Martian atmospheres.

  4. Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures

    DOE PAGES

    Seoung, Donghoon; Cynn, Hyunchae; Park, Changyong; Choi, Kwang -Yong; Blom, Douglas A.; Evans, William J.; Kao, Chi -Chang; Vogt, Thomas; Lee, Yongjae

    2014-09-01

    Pressure drastically alters the chemical and physical properties of materials and allows structural phase transitions and chemical reactions to occur that defy much of our understanding gained under ambient conditions. Particularly exciting is the high-pressure chemistry of xenon, which is known to react with hydrogen and ice at high pressures and form stable compounds. Here, we show that Ag16Al16Si24O8·16H2O (Ag-natrolite) irreversibly inserts xenon into its micropores at 1.7 GPa and 250 °C, while Ag+ is reduced to metallic Ag and possibly oxidized to Ag2+. In contrast to krypton, xenon is retained within the pores of this zeolite after pressure releasemore » and requires heat to desorb. This irreversible insertion and trapping of xenon in Ag-natrolite under moderate conditions sheds new light on chemical reactions that could account for the xenon deficiency relative to argon observed in terrestrial and Martian atmospheres.« less

  5. Selective Targeting of Extracellular Insulin-Degrading Enzyme by Quasi-Irreversible Thiol-Modifying Inhibitors.

    PubMed

    Abdul-Hay, Samer O; Bannister, Thomas D; Wang, Hui; Cameron, Michael D; Caulfield, Thomas R; Masson, Amandine; Bertrand, Juliette; Howard, Erin A; McGuire, Michael P; Crisafulli, Umberto; Rosenberry, Terrone R; Topper, Caitlyn L; Thompson, Caroline R; Schürer, Stephan C; Madoux, Franck; Hodder, Peter; Leissring, Malcolm A

    2015-12-18

    Many therapeutically important enzymes are present in multiple cellular compartments, where they can carry out markedly different functions; thus, there is a need for pharmacological strategies to selectively manipulate distinct pools of target enzymes. Insulin-degrading enzyme (IDE) is a thiol-sensitive zinc-metallopeptidase that hydrolyzes diverse peptide substrates in both the cytosol and the extracellular space, but current genetic and pharmacological approaches are incapable of selectively inhibiting the protease in specific subcellular compartments. Here, we describe the discovery, characterization, and kinetics-based optimization of potent benzoisothiazolone-based inhibitors that, by virtue of a unique quasi-irreversible mode of inhibition, exclusively inhibit extracellular IDE. The mechanism of inhibition involves nucleophilic attack by a specific active-site thiol of the enzyme on the inhibitors, which bear an isothiazolone ring that undergoes irreversible ring opening with the formation of a disulfide bond. Notably, binding of the inhibitors is reversible under reducing conditions, thus restricting inhibition to IDE present in the extracellular space. The identified inhibitors are highly potent (IC50(app) = 63 nM), nontoxic at concentrations up to 100 μM, and appear to preferentially target a specific cysteine residue within IDE. These novel inhibitors represent powerful new tools for clarifying the physiological and pathophysiological roles of this poorly understood protease, and their unusual mechanism of action should be applicable to other therapeutic targets.

  6. Irreversible Inhibition of Human Immunodeficiency Virus Type 1 Integrase by Dicaffeoylquinic Acids†

    PubMed Central

    Zhu, Kai; Cordeiro, Mara L.; Atienza, Jocelyn; Robinson, W. Edward; Chow, Samson A.

    1999-01-01

    Human immunodeficiency virus type 1 (HIV-1) and other retroviruses require integration of a double-stranded DNA copy of the RNA genome into the host cell chromosome for productive infection. The viral enzyme, integrase, catalyzes the integration of retroviral DNA and represents an attractive target for developing antiretroviral agents. We identified several derivatives of dicaffeoylquinic acids (DCQAs) that inhibit HIV-1 replication in tissue culture and catalytic activities of HIV-1 integrase in vitro. The specific step at which DCQAs inhibit the integration in vitro and the mechanism of inhibition were examined in the present study. Titration experiments with different concentrations of HIV-1 integrase or DNA substrate found that the effect of DCQAs was exerted on the enzyme and not the DNA. In addition to HIV-1, DCQAs also inhibited the in vitro activities of MLV integrase and truncated variants of feline immunodeficiency virus integrase, suggesting that these compounds interacted with the central core domain of integrase. The inhibition on retroviral integrases was relatively specific, and DCQAs had no effect on several other DNA-modifying enzymes and phosphoryltransferases. Kinetic analysis and dialysis experiments showed that the inhibition of integrase by DCQAs was irreversible. The inhibition did not require the presence of a divalent cation and was unaffected by preassembling integrase onto viral DNA. The results suggest that the irreversible inhibition by DCQAs on integrase is directed toward conserved amino acid residues in the central core domain during catalysis. PMID:10074185

  7. Reduction of combustion irreversibility in a gas turbine power plant through off-gas recycling

    SciTech Connect

    Harvey, S.P.; Richter, H.J.; Knoche, K.F.

    1995-01-01

    Combustion in conventional fossil-fueled power plants is highly irreversible, resulting in poor overall energy conversion efficiency values (less than 40 percent in many cases). The objective of this paper is to discuss means by which this combustion irreversibility might be reduced in gas turbine power cycles, and the conversion efficiency thus improved upon. One such means is thermochemical recuperation of exhaust heat. The proposed cycle recycles part of the exhaust gases, then mixes them with fuel prior to injection into a reformer. The heat required for the endothermic reforming reactions is provided by the hot turbine exhaust gases. Assuming state-of-the-art technology, and making a number of simplifying assumptions, an overall efficiency of 65.4 percent was attained for the cycle, based on the lower heating value (LHV) of the methane fuel. The proposed cycle is compared to a Humid Air Turbine (HAT) cycle with similar features that achieves an overall efficiency of 64.0 percent. The gain in cycle efficiency that can be attributed to the improved fuel oxidation process is 1.4 percentage points. Compared to current high-efficiency gas turbine cycles, the high efficiency of both cycles studied therefore results mainly from the use of staged compression and expansion with intermediate cooling and reheating, respectively.

  8. The evolution of plant reproductive systems: how often are transitions irreversible?

    PubMed Central

    Barrett, Spencer C. H.

    2013-01-01

    Flowering plants are characterized by striking variation in reproductive systems, and the evolutionary lability of their sexual traits is often considered a major driver of lineage diversification. But, evolutionary transitions in reproductive form and function are never entirely unconstrained and many changes exhibit strong directionality. Here, I consider why this occurs by examining transitions in pollination, mating and sexual systems, some of which have been considered irreversible. Among pollination systems, shifts from bee to hummingbird pollination are rarely reversible, whereas transitions from animal to wind pollination are occasionally reversed. Specialized pollination systems can become destabilized through a loss of pollinator service resulting in a return to generalized pollination, or more commonly a reliance on self-pollination. Homomorphic and heteromorphic self-incompatibility systems have multiple origins but breakdown to self-compatibility occurs much more frequently with little evidence for subsequent gains, at least over short time-spans. Similarly, numerous examples of the shift from outcrossing to predominant self-fertilization are known, but cases of reversal are very limited supporting the view that autogamy usually represents an evolutionary dead-end. The evolution of dioecy from hermaphroditism has also been considered irreversible, although recent evidence indicates that the occurrence of sex inconstancy and hybridization can lead to the origin of derived sexual systems from dioecy. The directionality of many transitions clearly refutes the notion of unconstrained reproductive flexibility, but novel adaptive solutions generally do not retrace earlier patterns of trait evolution. PMID:23825207

  9. Synthesis and characterization of diazomethylarachidonyl ketone: an irreversible inhibitor of N-arachidonylethanolamine amidohydrolase.

    PubMed

    Edgemond, W S; Greenberg, M J; McGinley, P J; Muthian, S; Campbell, W B; Hillard, C J

    1998-07-01

    N-Arachidonylethanolamine (AEA), a putative endogenous agonist of neuronal (CB1) cannabinoid receptors, is a substrate for N-arachidonylethanolamine amidohydrolase (AEA amidohydrolase), a serine amidase present in cell membranes. Following a strategy that has been used to develop inhibitors that covalently bind to the active site of serine peptidases, diazomethyl arachidonyl ketone (DAK) was synthesized and its effects on AEA amidohydrolase were determined. DAK inhibits the hydrolysis of AEA by rat brain membranes with an IC50 value of 0.5 microM. At low concentrations, DAK reduces the Vmax and increases the K(m) of the enzyme for its substrate AEA, which suggests that it is both a competitive and noncompetitive inhibitor. At higher concentrations, DAK inhibition is completely noncompetitive. DAK inhibition of membrane-associated AEA amidohydrolase is irreversible because hydrolytic activity is not restored with extensive washing or dialysis of the membranes. Furthermore, DAK inhibition is not reversible by anion exchange chromatography of the subsequently solubilized enzyme. In contrast, DAK inhibition of detergent-solubilized enzyme exhibits competitive kinetics and is reversible upon ion exchange chromatography. Exposure of C6 glioma cells to DAK results in concentration-related inhibition of AEA amidohydrolase activity in cellular membranes with an IC50 value of 0.3 microM. In summary, these studies demonstrate that DAK is an irreversible inhibitor of AEA amidohydrolase in its native membrane and provides a useful tool with which to study the role of AEA amidohydrolase in the termination of action of AEA.

  10. Irreversibly increased nitrogen fixation in Trichodesmium experimentally adapted to elevated carbon dioxide

    NASA Astrophysics Data System (ADS)

    Hutchins, David A.; Walworth, Nathan G.; Webb, Eric A.; Saito, Mak A.; Moran, Dawn; McIlvin, Matthew R.; Gale, Jasmine; Fu, Fei-Xue

    2015-09-01

    Nitrogen fixation rates of the globally distributed, biogeochemically important marine cyanobacterium Trichodesmium increase under high carbon dioxide (CO2) levels in short-term studies due to physiological plasticity. However, its long-term adaptive responses to ongoing anthropogenic CO2 increases are unknown. Here we show that experimental evolution under extended selection at projected future elevated CO2 levels results in irreversible, large increases in nitrogen fixation and growth rates, even after being moved back to lower present day CO2 levels for hundreds of generations. This represents an unprecedented microbial evolutionary response, as reproductive fitness increases acquired in the selection environment are maintained after returning to the ancestral environment. Constitutive rate increases are accompanied by irreversible shifts in diel nitrogen fixation patterns, and increased activity of a potentially regulatory DNA methyltransferase enzyme. High CO2-selected cell lines also exhibit increased phosphorus-limited growth rates, suggesting a potential advantage for this keystone organism in a more nutrient-limited, acidified future ocean.

  11. Time-resolved single-shot terahertz time-domain spectroscopy for ultrafast irreversible processes

    NASA Astrophysics Data System (ADS)

    Zhai, Zhao-Hui; Zhong, Sen-Cheng; Li, Jun; Zhu, Li-Guo; Meng, Kun; Li, Jiang; Liu, Qiao; Peng, Qi-Xian; Li, Ze-Ren; Zhao, Jian-Heng

    2016-09-01

    Pulsed terahertz spectroscopy is suitable for spectroscopic diagnostics of ultrafast events. However, the study of irreversible or single shot ultrafast events requires ability to record transient properties at multiple time delays, i.e., time resolved at single shot level, which is not available currently. Here by angular multiplexing use of femtosecond laser pulses, we developed and demonstrated a time resolved, transient terahertz time domain spectroscopy technique, where burst mode THz pulses were generated and then detected in a single shot measurement manner. The burst mode THz pulses contain 2 sub-THz pulses, and the time gap between them is adjustable up to 1 ns with picosecond accuracy, thus it can be used to probe the single shot event at two different time delays. The system can detect the sub-THz pulses at 0.1 THz-2.5 THz range with signal to noise ratio (SNR) of ˜400 and spectrum resolution of 0.05 THz. System design was described here, and optimizations of single shot measurement of THz pulses were discussed in detail. Methods to improve SNR were also discussed in detail. A system application was demonstrated where pulsed THz signals at different time delays of the ultrafast process were successfully acquired within single shot measurement. This time resolved transient terahertz time domain spectroscopy technique provides a new diagnostic tool for irreversible or single shot ultrafast events where dynamic information can be extracted at terahertz range within one-shot experiment.

  12. Kinetics of pore size during irreversible electrical breakdown of lipid bilayer membranes.

    PubMed Central

    Wilhelm, C; Winterhalter, M; Zimmermann, U; Benz, R

    1993-01-01

    The kinetics of pore formation followed by mechanical rupture of lipid bilayer membranes were investigated in detail by using the charge-pulse method. Membranes of various compositions were charged to a sufficiently high voltage to induce mechanical breakdown. The subsequent decrease of membrane voltage was used to calculate the conductance. During mechanical breakdown, which was probably caused by the widening of one single pore, the membrane conductance was a linear and not exponential function of time after the initial starting process. In a large number of experiments using various lipids and electrolytes, the characteristic opening process of the pore turned out to be independent of the actual membrane potential and electrolyte concentration. Our theoretical analysis of the pore formation suggested that the voltage-induced irreversible breakdown is due to a decrease in edge energy when the pore had formed. After initiation of the pore, the electrical contribution to surface tension is negligible. The time course of the increase of pore size shows that our model of the irreversible breakdown is in good agreement with mechanical properties of membranes reported elsewhere. PMID:8431536

  13. Irreversibly increased nitrogen fixation in Trichodesmium experimentally adapted to elevated carbon dioxide.

    PubMed

    Hutchins, David A; Walworth, Nathan G; Webb, Eric A; Saito, Mak A; Moran, Dawn; McIlvin, Matthew R; Gale, Jasmine; Fu, Fei-Xue

    2015-09-01

    Nitrogen fixation rates of the globally distributed, biogeochemically important marine cyanobacterium Trichodesmium increase under high carbon dioxide (CO2) levels in short-term studies due to physiological plasticity. However, its long-term adaptive responses to ongoing anthropogenic CO2 increases are unknown. Here we show that experimental evolution under extended selection at projected future elevated CO2 levels results in irreversible, large increases in nitrogen fixation and growth rates, even after being moved back to lower present day CO2 levels for hundreds of generations. This represents an unprecedented microbial evolutionary response, as reproductive fitness increases acquired in the selection environment are maintained after returning to the ancestral environment. Constitutive rate increases are accompanied by irreversible shifts in diel nitrogen fixation patterns, and increased activity of a potentially regulatory DNA methyltransferase enzyme. High CO2-selected cell lines also exhibit increased phosphorus-limited growth rates, suggesting a potential advantage for this keystone organism in a more nutrient-limited, acidified future ocean.

  14. An Efficient Site-Specific Method for Irreversible Covalent Labeling of Proteins with a Fluorophore

    PubMed Central

    Liu, Jiaquan; Hanne, Jeungphill; Britton, Brooke M.; Shoffner, Matthew; Albers, Aaron E.; Bennett, Jared; Zatezalo, Rachel; Barfield, Robyn; Rabuka, David; Lee, Jong-Bong; Fishel, Richard

    2015-01-01

    Fluorophore labeling of proteins while preserving native functions is essential for bulk Förster resonance energy transfer (FRET) interaction and single molecule imaging analysis. Here we describe a versatile, efficient, specific, irreversible, gentle and low-cost method for labeling proteins with fluorophores that appears substantially more robust than a similar but chemically distinct procedure. The method employs the controlled enzymatic conversion of a central Cys to a reactive formylglycine (fGly) aldehyde within a six amino acid Formylglycine Generating Enzyme (FGE) recognition sequence in vitro. The fluorophore is then irreversibly linked to the fGly residue using a Hydrazinyl-Iso-Pictet-Spengler (HIPS) ligation reaction. We demonstrate the robust large-scale fluorophore labeling and purification of E.coli (Ec) mismatch repair (MMR) components. Fluorophore labeling did not alter the native functions of these MMR proteins in vitro or in singulo. Because the FGE recognition sequence is easily portable, FGE-HIPS fluorophore-labeling may be easily extended to other proteins. PMID:26582263

  15. An Efficient Site-Specific Method for Irreversible Covalent Labeling of Proteins with a Fluorophore.

    PubMed

    Liu, Jiaquan; Hanne, Jeungphill; Britton, Brooke M; Shoffner, Matthew; Albers, Aaron E; Bennett, Jared; Zatezalo, Rachel; Barfield, Robyn; Rabuka, David; Lee, Jong-Bong; Fishel, Richard

    2015-01-01

    Fluorophore labeling of proteins while preserving native functions is essential for bulk Förster resonance energy transfer (FRET) interaction and single molecule imaging analysis. Here we describe a versatile, efficient, specific, irreversible, gentle and low-cost method for labeling proteins with fluorophores that appears substantially more robust than a similar but chemically distinct procedure. The method employs the controlled enzymatic conversion of a central Cys to a reactive formylglycine (fGly) aldehyde within a six amino acid Formylglycine Generating Enzyme (FGE) recognition sequence in vitro. The fluorophore is then irreversibly linked to the fGly residue using a Hydrazinyl-Iso-Pictet-Spengler (HIPS) ligation reaction. We demonstrate the robust large-scale fluorophore labeling and purification of E.coli (Ec) mismatch repair (MMR) components. Fluorophore labeling did not alter the native functions of these MMR proteins in vitro or in singulo. Because the FGE recognition sequence is easily portable, FGE-HIPS fluorophore-labeling may be easily extended to other proteins. PMID:26582263

  16. Cefazolin Irreversibly Inhibits Proliferation and Migration of Human Mesenchymal Stromal Cells

    PubMed Central

    Pilge, Hakan; Fröbel, Julia; Lensing-Höhn, Sabine; Zilkens, Christoph; Krauspe, Rüdiger

    2016-01-01

    Drugs may have a significant effect on postoperative bone healing by reducing the function of human mesenchymal stromal cells (hMSC) or mature osteoblasts. Although cefazolin is one of the most commonly used antibiotic drugs in arthroplasty to prevent infection worldwide, there is a lack of information regarding how cefazolin affects hMSC and therefore may have an effect on early bone healing. We studied the proliferation and migration capacity of primary hMSC during cefazolin treatment at various doses for up to 3 days, as well as the reversibility of the effects during the subsequent 3 days of culture without the drug. We found a time- and dose-dependent reduction of the proliferation rate and the migratory potential. Tests of whether these effects were reversible revealed that doses ≥250 μg/mL or treatments longer than 24 h irreversibly affected the cells. We are the first to show that application of cefazolin irreversibly inhibits the potential of hMSC for migration to the trauma site and local proliferation. Cefazolin should be administered only at the required dosage and time to prevent periprosthetic infection. If long-term administration is required and delayed bone healing is present, cefazolin application must be considered as a cause of delayed bone healing. PMID:27069918

  17. Catalytic irreversible inhibition of bacterial and plant arginine decarboxylase activities by novel substrate and product analogues.

    PubMed

    Bitonti, A J; Casara, P J; McCann, P P; Bey, P

    1987-02-15

    Arginine decarboxylase (ADC) activity from Escherichia coli and two plant species (oats and barley) was inhibited by five new substrate (arginine) and product (agmatine) analogues. The five compounds, (E)-alpha-monofluoromethyldehydroarginine (delta-MFMA), alpha-monofluoromethylarginine (MFMA), alpha-monofluoromethylagatine (FMA), alpha-ethynylagmatine (EA) and alpha-allenylagmatine (AA), were all more potent inhibitors of ADC activity than was alpha-difluoromethylarginine (DFMA), the only irreversible inhibitor of this enzyme described previously. The inhibition caused by the five compounds was apparently enzyme-activated and irreversible, since the loss of enzyme activity followed pseudo-first-order kinetics, was time-dependent, the natural substrate of ADC (arginine) blocked the effects of the inhibitors, and the inhibition remained after chromatography of inhibited ADC on Sephadex G-25 or on overnight dialysis of the enzyme. DFMA, FMA, delta-MFMA and MFMA were effective at very low concentrations (10 nM-10 microM) at inhibiting ADC activity in growing E. coli. FMA was also shown to deplete putrescine effectively in E. coli, particularly when combined with an inhibitor of ornithine decarboxylase, alpha-monofluoromethyl-putrescine. The potential uses of the compounds for the study of the role of polyamine biosynthesis in bacteria and plants is discussed.

  18. Catalytic irreversible inhibition of bacterial and plant arginine decarboxylase activities by novel substrate and product analogues.

    PubMed Central

    Bitonti, A J; Casara, P J; McCann, P P; Bey, P

    1987-01-01

    Arginine decarboxylase (ADC) activity from Escherichia coli and two plant species (oats and barley) was inhibited by five new substrate (arginine) and product (agmatine) analogues. The five compounds, (E)-alpha-monofluoromethyldehydroarginine (delta-MFMA), alpha-monofluoromethylarginine (MFMA), alpha-monofluoromethylagatine (FMA), alpha-ethynylagmatine (EA) and alpha-allenylagmatine (AA), were all more potent inhibitors of ADC activity than was alpha-difluoromethylarginine (DFMA), the only irreversible inhibitor of this enzyme described previously. The inhibition caused by the five compounds was apparently enzyme-activated and irreversible, since the loss of enzyme activity followed pseudo-first-order kinetics, was time-dependent, the natural substrate of ADC (arginine) blocked the effects of the inhibitors, and the inhibition remained after chromatography of inhibited ADC on Sephadex G-25 or on overnight dialysis of the enzyme. DFMA, FMA, delta-MFMA and MFMA were effective at very low concentrations (10 nM-10 microM) at inhibiting ADC activity in growing E. coli. FMA was also shown to deplete putrescine effectively in E. coli, particularly when combined with an inhibitor of ornithine decarboxylase, alpha-monofluoromethyl-putrescine. The potential uses of the compounds for the study of the role of polyamine biosynthesis in bacteria and plants is discussed. PMID:3297044

  19. DL-a-Monofluoromethylputrescine is a potent irreversible inhibitor of Escherichia coli ornithine decarboxylase.

    PubMed Central

    Kallio, A; McCann, P P; Bey, P

    1982-01-01

    DL-alpha-Monofluoromethylputrescine (compound R.M.I. 71864) is an enzyme-activated irreversible inhibitor of the biosynthetic enzyme ornithine decarboxylase from Escherichia coli. This compound, however, has much less effect in vitro on ornithine decarboxylase obtained from Pseudomonas aeruginosa. These findings are in contrast with those previously found with the substrate analogue DL-alpha-difluoromethylornithine (compound R.M.I. 71782). The K1 of the DL-alpha-monofluoromethylputrescine for the E. coli ornithine decarboxylase is 110 microM, and the half-life (t1/2) calculated for an infinite concentration of inhibitor is 2.1 min. When DL-alpha-monofluoromethylputrescine is used in combination with DL-alpha-difluoromethylarginine (R.M.I. 71897), an irreversible inhibitor of arginine decarboxylase, in vivo in E. coli, both decarboxylase activities are inhibited (greater than 95%) but putrescine levels are only decreased to about one-third of control values and spermidine levels are slightly increased. PMID:6812566

  20. Irreversible properties of YBCO thick films deposited by liquid phase epitaxy on single crystalline substrates

    NASA Astrophysics Data System (ADS)

    Vostner, A.; Tönies, S.; Weber, H. W.; Cheng, Y. S.; Kurumovic, A.; Evetts, J. E.; Mennema, S. H.; Zandbergen, H. W.

    2003-10-01

    We report on the field and temperature dependence of the critical transport current density Jc, the angular dependence of the transport current at various external magnetic fields and the irreversibility fields in YBa2Cu3O7-delta (Y-123) thick films prepared by liquid phase epitaxy (LPE). A comparison of the irreversible properties between specimens produced with and without silver additions to the melt is also presented. Transmission electron microscopy (TEM) was employed to obtain information on the correlation between the transport properties and the microstructure. The samples were deposited either directly on NdGaO3 (NGO) or on seeded (100) MgO substrates, where a 200 nm thin YBCO film deposited by pulsed laser deposition (PLD) acts as seed layer for the LPE process. The final thickness of the Y-123 layer is of the order of 1 µm for the NGO and between 2 and 10 µm for the MgO samples. The critical current densities reach 3 × 109 A m-2 at zero field and 77 K in the best case.

  1. Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures.

    PubMed

    Seoung, Donghoon; Lee, Yongmoon; Cynn, Hyunchae; Park, Changyong; Choi, Kwang-Yong; Blom, Douglas A; Evans, William J; Kao, Chi-Chang; Vogt, Thomas; Lee, Yongjae

    2014-09-01

    Pressure drastically alters the chemical and physical properties of materials and allows structural phase transitions and chemical reactions to occur that defy much of our understanding gained under ambient conditions. Particularly exciting is the high-pressure chemistry of xenon, which is known to react with hydrogen and ice at high pressures and form stable compounds. Here, we show that Ag16Al16Si24O8·16H2O (Ag-natrolite) irreversibly inserts xenon into its micropores at 1.7 GPa and 250 °C, while Ag(+) is reduced to metallic Ag and possibly oxidized to Ag(2+). In contrast to krypton, xenon is retained within the pores of this zeolite after pressure release and requires heat to desorb. This irreversible insertion and trapping of xenon in Ag-natrolite under moderate conditions sheds new light on chemical reactions that could account for the xenon deficiency relative to argon observed in terrestrial and Martian atmospheres. PMID:25143221

  2. A study of severance taxes on crude oil and natural gas: The irreversibility of taxation

    NASA Astrophysics Data System (ADS)

    Brandly, Mark L.

    This dissertation examines the institution of severance taxes. An explanation of the property rights allocations in the petroleum industry provides the foundation for discussing the incentive structure of the industry. This explanation concludes that the severance tax burden on the supply side of the industry is born by oil producers and royalty owners. A history of national and state severance taxes in the United States is provided. The literature on the justifications for severance taxes and the economic studies that are relevant to the issue of the tax effect on oil output is reviewed. This review shows that an important implication of severance taxes, the fact that the output effect of such taxes is at least partially irreversible, has been overlooked. A mathematical model is constructed that demonstrates the relationships between output, the sellers' price, the buyers' price, excess burden, the consumers' tax burden, the producers' tax burden, and the price elasticities of supply and demand. It is then demonstrated that the appropriate framework for analyzing severance taxes includes an upward sloping supply curve and a completely elastic demand curve. Another mathematical model shows the effect that a severance tax has on the output decision given different income tax situations. A review of the industry procedures for abandoning wells is followed by a theoretical argument that severance taxes are irreversible to some degree. When a well is abandoned, due to a severance tax, the well is plugged with cement. The costs of reentering such a well are large relative to the potential profits to be derived from such a decision. Eliminating the severance tax does not provide the incentive needed to reenter and produce an abandoned well. An empirical examination of the Kansas severance tax imposed in 1983 compares the present value of an abandoned well with the costs of reentering such a well. This comparison leads to the conclusion that, generally, a well that was

  3. Selective and irreversible inhibitors of mosquito acetylcholinesterases for controlling malaria and other mosquito-borne diseases.

    PubMed

    Pang, Yuan-Ping; Ekström, Fredrik; Polsinelli, Gregory A; Gao, Yang; Rana, Sandeep; Hua, Duy H; Andersson, Björn; Andersson, Per Ola; Peng, Lei; Singh, Sanjay K; Mishra, Rajesh K; Zhu, Kun Yan; Fallon, Ann M; Ragsdale, David W; Brimijoin, Stephen

    2009-01-01

    New insecticides are urgently needed because resistance to current insecticides allows resurgence of disease-transmitting mosquitoes while concerns for human toxicity from current compounds are growing. We previously reported the finding of a free cysteine (Cys) residue at the entrance of the active site of acetylcholinesterase (AChE) in some insects but not in mammals, birds, and fish. These insects have two AChE genes (AP and AO), and only AP-AChE carries the Cys residue. Most of these insects are disease vectors such as the African malaria mosquito (Anopheles gambiae sensu stricto) or crop pests such as aphids. Recently we reported a Cys-targeting small molecule that irreversibly inhibited all AChE activity extracted from aphids while an identical exposure caused no effect on the human AChE. Full inhibition of AChE in aphids indicates that AP-AChE contributes most of the enzymatic activity and suggests that the Cys residue might serve as a target for developing better aphicides. It is therefore worth investigating whether the Cys-targeting strategy is applicable to mosquitocides. Herein, we report that, under conditions that spare the human AChE, a methanethiosulfonate-containing molecule at 6 microM irreversibly inhibited 95% of the AChE activity extracted from An. gambiae s. str. and >80% of the activity from the yellow fever mosquito (Aedes aegypti L.) or the northern house mosquito (Culex pipiens L.) that is a vector of St. Louis encephalitis. This type of inhibition is fast ( approximately 30 min) and due to conjugation of the inhibitor to the active-site Cys of mosquito AP-AChE, according to our observed reactivation of the methanethiosulfonate-inhibited AChE by 2-mercaptoethanol. We also note that our sulfhydryl agents partially and irreversibly inhibited the human AChE after prolonged exposure (>4 hr). This slow inhibition is due to partial enzyme denaturation by the inhibitor and/or micelles of the inhibitor, according to our studies using atomic force

  4. Irreversible volume growth in polymer-bonded powder systems: effects of crystalline anisotropy, particle size distribution, and binder strength

    SciTech Connect

    Maiti, A; Gee, R H; Hoffman, D; Fried, L E

    2007-08-22

    Pressed-powdered crystallites of intrinsically anisotropic materials have been shown to undergo irreversible volume expansion when subjected to repeated cycles of heating and cooling. We develop a coarse-grained (micron-scale) interaction Hamiltonian for this system and perform molecular dynamics simulations, which quantitatively reproduce the experimentally observed irreversible growth. The functional form and values of the interaction parameters at the coarse-grained level are motivated by our knowledge at the atomic/molecular scale, and allows a simple way to incorporate the effect of polymeric binder. We demonstrate that irreversible growth happens only in the presence of intrinsic crystalline anisotropy of the powder material, is mediated by particles much smaller than the average crystallite size, and can be significantly reduced in the presence of high-strength polymeric binder with elevated glass transition temperatures.

  5. Sudden irreversibility collapse in YBaCuO crystals: Possible evidence for thermal softening of the core pinning

    SciTech Connect

    Krusin-Elbaum, L.; Civale, L.; Holtzberg, F.; Malozemoff, A.P.; Feild, C. )

    1991-11-25

    We report a new transition in the magnetic ({ital H}-{ital T}) phase diagram of the high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7}. A sharp ({Delta}{ital T}{congruent}0.020 K) step in the irreversibility line is observed within about 1 K of {ital T}{sub {ital c}} at fields considerably above the lower critical field. A contour map probing nonlinear region of the {ital H}-{ital T} plane reveals a backflow'' and reentrant behavior below the irreversibility line, reflecting the collapse step. These observations are consistent with the existence of a thermal softening boundary which crosses the irreversibility line in {ital H}-{ital T} plane, and at which vortex cores are delocalized on the scale of the coherence length {xi}.

  6. Rapid Determination of the Specificity Constant of Irreversible Inhibitors (kinact/KI) by Means of an Endpoint Competition Assay.

    PubMed

    Miyahisa, Ikuo; Sameshima, Tomoya; Hixon, Mark S

    2015-11-16

    Owing to their covalent target occupancy, irreversible inhibitors require low exposures and offer long duration, and their use thus represents a powerful strategy for achieving pharmacological efficacy. Importantly, the potency metric of irreversible inhibitors is kinact/KI not IC50. A simple approach to measuring kinact/KI was developed that makes use of an irreversible probe for competitive assays run to completion against test compounds. In this system, the kinact/KI value of the test compound is equal to (kinact/KI)probe ×[probe]/IC50. The advantages of this method include simplicity, high throughput, and application to all target classes, and it only requires an in-depth kinetic evaluation of the probe.

  7. Influence of Irreversible Adsorption on the Glass Transition Temperature of Polymer Thin Films as Measured by Fluorescence

    NASA Astrophysics Data System (ADS)

    Burroughs, Mary; Priestley, Rodney

    2014-03-01

    Polymers confined to the nanometer length scale have been shown to exhibit deviations in the glass transition temperature (Tg) from the bulk. With the increasing use of confined polymers in nanotechnology, understanding and predicting this behavior is extremely relevant to industries ranging from pharmaceuticals to organic electronics. Recent work (Napolitano, Wübbenhorst, Nature Communications, 2, 260 (2011)) has connected deviations in Tg under confinement with irreversible physical adsorption of polymer chains at substrate interfaces. Here we investigate the influence of irreversibly adsorbed layers on the Tg of polystyrene (PS) thin films supported on silica via fluorescence. We examine the Tg of the brushes as a function of annealing time and irreversibly adsorbed layer thickness. By incorporating fluorescently labeled polymer layers into multilayered films of unlabeled polymer, we will examine the influence of brushes on adjacent layers dynamics. Finally, we will compare the results on PS with those of poly(methyl methacrylate).

  8. Effect of irreversible electroporation on three-dimensional cell culture model.

    PubMed

    Kurata, Kosaku; Matsushita, Masahiro; Yoshii, Takashi; Fukunaga, Takanobu; Takamatsu, Hiroshi

    2012-01-01

    Irreversible electroporation (IRE) is a new treatment to necrotize abnormal cells by high electric pulses. Electric potential difference over 1 V across the plasma membrane permanently permeabilizes the cell with keeping the extracellular matrix intact if the thermal damage due to the Joule heating effect is avoided. This is the largest advantage of the IRE compared to the other conventional treatment. However, since the IRE has just started to be used in clinical tests, it is important to predict the necrotized region that depends on pulse parameters and electrode arrangement. We therefore examined the numerical solution to the Laplace equation for the static electric field to predict the IRE-induced cell necrosis. Three-dimensionally (3-D) cultured cells in a tissue phantom were experimentally subjected to the electric pulses through a pair of puncture electrodes. The necrotized area was determined as a function of the pulse repetition and compared with the area that was estimated by the numerical analysis. PMID:23365861

  9. Thermodynamics of Irreversible Processes Applied to Solute Transport in Non Saturated Porous Media

    NASA Astrophysics Data System (ADS)

    Mathieu-Balster, I.; Sicard, J.

    1999-09-01

    Modeling of solute transport in non-saturated and non-isothermal porous media is dealt with by thermodynamics of irreversible processes. This rigorous approach enables us to consider the different kinds of transfer and the coupling. Every physical phenomenon as water phase transition and solute adsorption by the solid matrix can be taken into account. The final model may be applied to several fields such as civil engineering, agronomy, pollution and the assessment of radioactive waste repositories. A numerical modeling taking into account the effect of temperature gradient on solute transport (“Soret effect”) is in the process of implementation in the French software “CESAR-LCPC” of the “Laboratoire Central des Ponts et Chaussées”.

  10. Kinetics of irreversible inhibition of yeast alcohol dehydrogenase during modification by o-phthaldehyde.

    PubMed

    Le, W P; Yan, S X; Huang, M Q; Zhang, Y X; Zhou, H M

    The kinetic theory of the substrate reaction during irreversible inhibition of enzyme activity described previously has been applied to a study on the kinetics of the course of inactivation of yeast alcohol dehydrogenase (YADH) by o-phthaldehyde (OPTA). The microscopic constants for the reaction of the inactivators with the free enzyme and with the enzyme-substrate complexes were determined. The inactivation is a monophasic pseudo-first-order reaction with OPTA. The apparent rate constant A is independent of the OPTA concentration, indicating that the inactivation is a noncomplexing inhibition. The marked protective effect of substrates on the inactivation of YADH by OPTA has been observed. This result suggests that the modification of the enzyme by OPTA may occur at the active site.

  11. A study using irreversible electroporation to treat large, irregular tumors in a canine patient.

    PubMed

    Neal, Robert E; Garcia, Paulo A; Rossmeisl, John H; Davalos, Rafael V

    2010-01-01

    Irreversible electroporation (IRE) has shown promise for the therapeutic treatment of focal disease, including tumors. The effects of treatment are dependent on the electric field distribution, which may be predicted with numerical modeling. In order to improve the effectiveness and scope of IRE therapies, techniques must be developed for designing protocols capable of treating large and irregular tumors. We present the findings of a study designing an IRE treatment plan for a canine patient using medical imaging analysis and reconstruction, numerical modeling, and real-time electrode placement guidance. The executed plan was able to alleviate the patient's clinical symptoms without damaging any of the nearby sensitive tissues in a complex heterogeneous environment. PMID:21095963

  12. Beta-aminoketones as prodrugs for selective irreversible inhibitors of type-1 methionine aminopeptidases.

    PubMed

    Altmeyer, Markus; Amtmann, Eberhard; Heyl, Carina; Marschner, Aline; Scheidig, Axel J; Klein, Christian D

    2014-11-15

    We identified and characterized β-aminoketones as prodrugs for irreversible MetAP inhibitors that are selective for the MetAP-1 subtype. β-Aminoketones with certain structural features form α,β-unsaturated ketones under physiological conditions, which bind covalently and selectively to cysteines in the S1 pocket of MetAP-1. The binding mode was confirmed by X-ray crystallography and assays with the MetAPs from Escherichia coli, Staphylococcus aureus and both human isoforms. The initially identified tetralone derivatives showed complete selectivity for E. coli MetAP versus human MetAP-1 and MetAP-2. Rational design of indanone analogs yielded compounds with selectivity for the human type-1 versus the human type-2 MetAP.

  13. Activation of Inhibitors by Sortase Triggers Irreversible Modification of the Active Site*S

    PubMed Central

    Maresso, Anthony W.; Wu, Ruiying; Kern, Justin W.; Zhang, Rongguang; Janik, Dorota; Missiakas, Dominique M.; Duban, Mark-Eugene; Joachimiak, Andrzej; Schneewind, Olaf

    2011-01-01

    Sortases anchor surface proteins to the cell wall of Gram-positive pathogens through recognition of specific motif sequences. Loss of sortase leads to large reductions in virulence, which identifies sortase as a target for the development of antibacterials. By screening 135,625 small molecules for inhibition, we report here that aryl (β-amino)ethyl ketones inhibit sortase enzymes from staphylococci and bacilli. Inhibition of sortases occurs through an irreversible, covalent modification of their active site cysteine. Sortases specifically activate this class of molecules via β-elimination, generating a reactive olefin intermediate that covalently modifies the cysteine thiol. Analysis of the three-dimensional structure of Bacillus anthracis sortase B with and without inhibitor provides insights into the mechanism of inhibition and reveals binding pockets that can be exploited for drug discovery. PMID:17545669

  14. Discovery of Tumor-Specific Irreversible Inhibitors of Stearoyl CoA Desaturase

    PubMed Central

    Theodoropoulos, Panayotis C.; Gonzales, Stephen S.; Winterton, Sarah E.; Rodriguez-Navas, Carlos; McKnight, John S.; Morlock, Lorraine K.; Hanson, Jordan M.; Cross, Bethany; Owen, Amy E.; Duan, Yingli; Moreno, Jose R.; Lemoff, Andrew; Mirzaei, Hamid; Posner, Bruce A.; Williams, Noelle S.

    2016-01-01

    A hallmark of targeted cancer therapies is selective toxicity among cancer cell lines. We evaluated results from a viability screen of over 200,000 small molecules to identify two chemical series, oxalamides and benzothiazoles, that were selectively toxic to the same four of 12 human lung cancer cell lines at low nanomolar concentrations. Sensitive cell lines expressed cytochrome P450 (CYP) 4F11, which metabolized the compounds into irreversible stearoyl CoA desaturase (SCD) inhibitors. SCD is recognized as a promising biological target in cancer and metabolic disease. However, SCD is essential to sebocytes, and accordingly SCD inhibitors cause skin toxicity. Mouse sebocytes were unable to activate the benzothiazoles or oxalamides into SCD inhibitors, providing a therapeutic window for inhibiting SCD in vivo. We thus offer a strategy to target SCD in cancer by taking advantage of high CYP expression in a subset of tumors. PMID:26829472

  15. Thiuram Disulfides as Pseudo-irreversible Inhibitors of the Lymphoid Tyrosine Phosphatase

    PubMed Central

    Kulkarni, Rhushikesh A.; Stanford, Stephanie M.; Vellore, Nadeem A.; Krishnamurthy, Divya; Bliss, Matthew R.; Baron, Riccardo; Bottini, Nunzio; Barrios, Amy M.

    2013-01-01

    We have screened a small library of thiuram disulfides for inhibition of lymphoid tyrosine phosphatase (LYP) activity. The parent thiuram disulfide, disulfiram, inhibited LYP activity in vitro and in Jurkat T cells whereas diethyldithiocarbamate failed to inihibit LYP at the concentrations tested. Compound 13, an N-(2-thioxothiazolidin-4-one) analog, was the most potent LYP inhibitor in this series, with an IC50 of 3 μM. Compound 13 was found to inhibit LYP pseudo-irreversibly, as evident by the time-dependence of inhibition with a Ki of 1.1 μM and a kinact of 0.004 s−1. The inhibition of LYP by compound 13 could not be reversed significantly by incubation with glutathione or by prolonged dialysis, but could be partially reversed by incubation with dithiothreitol. Compound 13 also inhibited LYP activity in Jurkat T cells. PMID:23873737

  16. Thiuram disulfides as pseudo-irreversible inhibitors of lymphoid tyrosine phosphatase.

    PubMed

    Kulkarni, Rhushikesh A; Stanford, Stephanie M; Vellore, Nadeem A; Krishnamurthy, Divya; Bliss, Matthew R; Baron, Riccardo; Bottini, Nunzio; Barrios, Amy M

    2013-09-01

    We screened a small library of thiuram disulfides for inhibition of lymphoid tyrosine phosphatase (LYP) activity. The parent thiuram disulfide, disulfiram, inhibited LYP activity in vitro and in Jurkat T cells, whereas diethyldithiocarbamate failed to inhibit LYP at the concentrations tested. Compound 13, an N-(2-thioxothiazolidin-4-one) analogue, was found to be the most potent LYP inhibitor in this series, with an IC50 value of 3 μM. Compound 13 inhibits LYP pseudo-irreversibly, as evidenced by the time-dependence of inhibition, with a K(i) value of 1.1 μM and a k(inact) value of 0.004 s⁻¹. The inhibition of LYP by compound 13 could not be reversed significantly by incubation with glutathione or by prolonged dialysis, but could be partially reversed by incubation with dithiothreitol. Compound 13 also inhibited LYP activity in Jurkat T cells.

  17. Study on the irreversible thermodynamics of a marine engine exhaust-powered adsorption refrigerating system

    NASA Astrophysics Data System (ADS)

    Xie, Yingchun; Mei, Ning; Xu, Zhen

    2006-04-01

    This study investigates the heat and mass transfer mechanism of a marine engine exhaust-powered adsorption refrigerating system by using irreversible thermodynamics. The equations of entropy-production rate and the linear phenomenological equations of thermodynamic flux and force are established. The conventional experimental facilities of unit tube are developed and the phenomenological coefficients are obtained by fitting the experimental data. It is concluded that the thermodynamic process in the adsorbent bed is determined by the coupling effect of the heat and mass transfer; furthermore, the mass transfer is determined by the heat transfer. Taking some measures to increase heat transfer can improve the performance of the adsorption refrigerating system. The conclusions presented in this paper may be of value to the engineering applications of the system.

  18. Fast x-ray microdiffraction techniques for studying irreversible transformations in materials.

    SciTech Connect

    Kelly, S. T.; Trenkle, J. C.; Koerner, L. J.; Barron, S. C.; Walker, N.; Pouliquen, P. O.; Tate, M. W.; Gruner, S. M.; Dufresne, E. M.; Weihs, T. P.; Hufnagel, T. C.

    2011-05-01

    A pair of techniques have been developed for performing time-resolved X-ray microdiffraction on irreversible phase transformations. In one technique capillary optics are used to focus a high-flux broad-spectrum X-ray beam to a 60 {micro}m spot size and a fast pixel array detector is used to achieve temporal resolution of 55 {micro}s. In the second technique the X-rays are focused with Kirkpatrick-Baez mirrors to achieve a spatial resolution better than 10 {micro}m and a fast shutter is used to provide temporal resolution better than 20 {micro}s while recording the diffraction pattern on a (relatively slow) X-ray CCD camera. Example data from experiments are presented where these techniques are used to study self-propagating high-temperature synthesis reactions in metal laminate foils.

  19. Irreversible transitions in the exchange-striction model of spin-glass state

    NASA Astrophysics Data System (ADS)

    Valkov, V. I.; Golovchan, A. V.

    2014-08-01

    Based on the assumption of a negative volume dependence of random exchange integrals, it is possible to switch to a compressible Sherrington-Kirkpatrick spin-glass model. Within the proposed model, temperature-pressure phase diagrams were calculated and pressure- and magnetic-field-induced first-order phase transitions from the initial paramagnetic and spin-glass states to the ferromagnetic state were predicted. It was shown that the application of pressure in the spin-glass state not only increases and shifts magnetic susceptibility, but also reduces the critical magnetic fields of irreversible induced phase transitions from the spin-glass to the ferromagnetic state. The obtained results are used to describe the spin-glass state in (Sm1-xGdx)0.55Sr0.45MnO3.

  20. Arterial complication of irreversible electroporation procedure for locally advanced pancreatic cancer

    PubMed Central

    Ekici, Yahya; Tezcaner, Tugan; Aydın, Hüseyin Onur; Boyvat, Fatih; Moray, Gökhan

    2016-01-01

    Irreversible electroporation (IRE) is a non-thermal ablation technique used especially in locally advanced pancreatic carcinomas that are considered surgically unresectable. We present the first case of acute superior mesenteric artery (SMA) occlusion secondary to pancreatic IRE procedure that has not been reported before in the literature. A 66-year-old man underwent neoadjuvant chemoradiotherapy for locally advanced pancreatic ductal adenocarcinoma. IRE procedure was applied to the patient during laparotomy under general anesthesia. After finishing the procedure, an acute intestinal ischemia was detected. A conventional vascular angiography was performed and a metallic stent was successfully placed to the SMA and blood flow was maintained. It is important to be careful in such cases of tumor involvement of SMA when evaluating for IRE procedure of pancreatic tumor. PMID:27795815

  1. Chemical modeling of irreversible reactions in nuclear waste-water-rock systems

    SciTech Connect

    Wolery, T.J.

    1981-02-01

    Chemical models of aqueous geochemical systems are usually built on the concept of thermodynamic equilibrium. Though many elementary reactions in a geochemical system may be close to equilibrium, others may not be. Chemical models of aqueous fluids should take into account that many aqueous redox reactions are among the latter. The behavior of redox reactions may critically affect migration of certain radionuclides, especially the actinides. In addition, the progress of reaction in geochemical systems requires thermodynamic driving forces associated with elementary reactions not at equilibrium, which are termed irreversible reactions. Both static chemical models of fluids and dynamic models of reacting systems have been applied to a wide spectrum of problems in water-rock interactions. Potential applications in nuclear waste disposal range from problems in geochemical aspects of site evaluation to those of waste-water-rock interactions. However, much further work in the laboratory and the field will be required to develop and verify such applications of chemical modeling.

  2. Irreversibility in a unitary finite-rate protocol: the concept of internal friction

    NASA Astrophysics Data System (ADS)

    Çakmak, Selçuk; Altintas, Ferdi; Müstecaplıoğlu, Özgür E.

    2016-07-01

    The concept of internal friction, a fully quantum mechanical phenomena, is investigated in a simple, experimentally accessible quantum system in which a spin-1/2 is driven by a transverse magnetic field in a quantum adiabatic process. The irreversible production of the waste energy due to the quantum friction is quantitatively analyzed in a forward-backward unitary transform of the system Hamiltonian by using the quantum relative entropy between the actual density matrix obtained in a parametric transformation and the one in a reversible adiabatic process. Analyzing the role of total transformation time and the different pulse control schemes on the internal friction reveal the non-monotone character of the internal friction as a function of the total protocol time and the possibility for almost frictionless solutions in finite-time transformations.

  3. Irreversible altering of crystalline phase of phase-change Ge-Sb thin films

    SciTech Connect

    Krusin-Elbaum, L.; Shakhvorostov, D.; Cabral, C. Jr.; Raoux, S.; Jordan-Sweet, J. L.

    2010-03-22

    The stability of the crystalline phase of binary phase-change Ge{sub x}Sb{sub 1-x} films is investigated over a wide range of Ge content. From Raman spectroscopy we find the Ge-Sb crystalline structure irreversibly altered after exposure to a laser beam. We show that with increasing beam intensity/temperature Ge agglomerates and precipitates out in the amount growing with x. A simple empirical relation links Ge precipitation temperature T{sub Ge}{sup p} to the rate of change dT{sub cryst}/dx of crystallization, with the precipitation easiest on the mid-range x plateau, where T{sub cryst} is nearly constant. Our findings point to a preferable 15% < or approx. x < 50% window, that may achieve the desired cycling/archival properties of a phase-change cell.

  4. Groundwater sapping as the cause of irreversible desertification of Hunshandake Sandy Lands, Inner Mongolia, northern China

    PubMed Central

    Yang, Xiaoping; Scuderi, Louis A.; Wang, Xulong; Scuderi, Louis J.; Zhang, Deguo; Li, Hongwei; Forman, Steven; Xu, Qinghai; Wang, Ruichang; Huang, Weiwen; Yang, Shixia

    2015-01-01

    In the middle-to-late Holocene, Earth’s monsoonal regions experienced catastrophic precipitation decreases that produced green to desert state shifts. Resulting hydrologic regime change negatively impacted water availability and Neolithic cultures. Whereas mid-Holocene drying is commonly attributed to slow insolation reduction and subsequent nonlinear vegetation–atmosphere feedbacks that produce threshold conditions, evidence of trigger events initiating state switching has remained elusive. Here we document a threshold event ca. 4,200 years ago in the Hunshandake Sandy Lands of Inner Mongolia, northern China, associated with groundwater capture by the Xilamulun River. This process initiated a sudden and irreversible region-wide hydrologic event that exacerbated the desertification of the Hunshandake, resulting in post-Humid Period mass migration of northern China’s Neolithic cultures. The Hunshandake remains arid and is unlikely, even with massive rehabilitation efforts, to revert back to green conditions. PMID:25561539

  5. Coalescence behavior of oil droplets coated in irreversibly-adsorbed surfactant layers.

    PubMed

    Reichert, Matthew D; Walker, Lynn M

    2015-07-01

    Coalescence between oil caps with irreversibly adsorbed layers of nonionic surfactant is characterized in deionized water and electrolyte solution. The coalescence is characterized using a modified capillary tensiometer allowing for accurate measurement of the coalescence time. Results suggest two types of coalescence behavior, fast coalescence at low surface coverages that are independent of ionic strength and slow coalescence at high coverage. These slow coalescence events (orders of magnitude slower) are argued to be due to electric double layer forces or more complicated stabilization mechanisms arising from interfacial deformation and surface forces. A simple film drainage model is used in combination with measured values for interfacial properties to quantify the interaction potential between the two interfaces. Since this approach allows the two caps to have the same history, interfacial coverage and curvature, the results offer a tool to better understand a mechanism that is important to emulsion stability.

  6. Irreversible Inhibition of Glutathione S-Transferase by Phenethyl Isothiocyanate (PEITC), a Dietary Cancer Chemopreventive Phytochemical

    PubMed Central

    Kumari, Vandana; Dyba, Marzena A.; Holland, Ryan J.; Liang, Yu-He; Singh, Shivendra V.

    2016-01-01

    Dietary isothiocyanates abundant as glucosinolate precursors in many edible cruciferous vegetables are effective for prevention of cancer in chemically-induced and transgenic rodent models. Some of these agents, including phenethyl isothiocyanate (PEITC), have already advanced to clinical investigations. The primary route of isothiocyanate metabolism is its conjugation with glutathione (GSH), a reaction catalyzed by glutathione S-transferase (GST). The pi class GST of subunit type 1 (hGSTP1) is much more effective than the alpha class GST of subunit type 1 (hGSTA1) in catalyzing the conjugation. Here, we report the crystal structures of hGSTP1 and hGSTA1 each in complex with the GSH adduct of PEITC. We find that PEITC also covalently modifies the cysteine side chains of GST, which irreversibly inhibits enzymatic activity. PMID:27684484

  7. Effects of oxymorphazone in frogs: long lasting antinociception in vivo, and apparently irreversible binding in vitro

    SciTech Connect

    Benyhe, S.; Hoffman, G.; Varga, E.; Hosztafi, S.; Toth, G.; Borsodi, A.; Wollemann, M.

    1989-01-01

    Oxymorphazone was found to be a relatively weak antinociceptive drug in intact frog (Rana esculenta) when acetic acid was used as pain stimulus. Frogs remained analgesic for at least 48 hrs following oxymorphazone administration. The ligand increased the latency of wiping reflex in spinal frogs too. There effects were blocked by naloxone. In equilibrium binding studies (/sup 3/H)oxymorphazone had high affinity to the opioid receptors of frog brain and spinal cord as well. Kinetic experiments show that only 25% of the bound (/sup 3/H)oxymorphazone is readily dissociable. Preincubation of the membranes with labeled oxymorphazone results in a washing resistant inhibition of the opioid binding sites. At least 70% of the (/sup 3/H)oxymorphazone specific binding is apparently irreversible after reaction at 5 nM ligand concentration, and this can be enhanced by a higher concentration of tritiated ligand.

  8. Graphical Analysis of PET Data Applied to Reversible and Irreversible Tracers

    SciTech Connect

    Logan, Jean

    1999-11-18

    Graphical analysis refers to the transformation of multiple time measurements of plasma and tissue uptake data into a linear plot, the slope of which is related to the number of available tracer binding sites. This type of analysis allows easy comparisons among experiments. No particular model structure is assumed, however it is assumed that the tracer is given by bolus injection and that both tissue uptake and the plasma concentration of unchanged tracer are monitored following tracer injection. The requirement of plasma measurements can be eliminated in some cases when a reference region is available. There are two categories of graphical methods which apply to two general types of ligands--those which bind reversibly during the scanning procedure and those which are irreversible or trapped during the time of the scanning procedure.

  9. Efficiency at maximum power output of an irreversible Carnot-like cycle with internally dissipative friction.

    PubMed

    Wang, Jianhui; He, Jizhou

    2012-11-01

    We investigate the efficiency at the maximum power output (EMP) of an irreversible Carnot engine performing finite-time cycles between two reservoirs at constant temperatures T(h) and T(c) (

  10. Exploring the optimal performances of irreversible single resonance energy selective electron refrigerators

    NASA Astrophysics Data System (ADS)

    Zhou, Junle; Chen, Lingen; Ding, Zemin; Sun, Fengrui

    2016-05-01

    Applying finite-time thermodynamics (FTT) and electronic transport theory, the optimal performances of irreversible single resonance energy selective electron (ESE) refrigerator are analyzed. The effects of heat leakage between two electron reservoirs on optimal performances are discussed. The influences of system operating parameters on cooling load, coefficient of performance (COP), figure of merit and ecological function are demonstrated using numerical examples. Comparative performance analyses among different objective functions show that performance characteristics at maximum ecological function and maximum figure of merit are of great practical significance. Combining the two optimization objectives of maximum ecological function and maximum figure of merit together, more specific optimal ranges of cooling load and COP are obtained. The results can provide some advices to the design of practical electronic machine systems.

  11. The Law of Self-Acting Machines and Irreversible Processes with Reversible Replicas

    NASA Astrophysics Data System (ADS)

    Valev, Pentcho

    2002-11-01

    Clausius and Kelvin saved Carnot theorem and developed the second law by assuming that Carnot machines can work in the absence of an operator and that all the irreversible processes have reversible replicas. The former assumption restored Carnot theorem as an experience of mankind whereas the latter generated "the law of ever increasing entropy". Both assumptions are wrong so it makes sense to return to Carnot theorem (or some equivalent) and test it experimentally. Two testable paradigms - the system performing two types of reversible work and the system in dynamical equilibrium - suggest that perpetuum mobile of the second kind in the presence of an operator is possible. The deviation from the second law prediction, expressed as difference between partial derivatives in a Maxwell relation, measures the degree of structural-functional evolution for the respective system.

  12. Groundwater sapping as the cause of irreversible desertification of Hunshandake Sandy Lands, Inner Mongolia, northern China.

    PubMed

    Yang, Xiaoping; Scuderi, Louis A; Wang, Xulong; Scuderi, Louis J; Zhang, Deguo; Li, Hongwei; Forman, Steven; Xu, Qinghai; Wang, Ruichang; Huang, Weiwen; Yang, Shixia

    2015-01-20

    In the middle-to-late Holocene, Earth's monsoonal regions experienced catastrophic precipitation decreases that produced green to desert state shifts. Resulting hydrologic regime change negatively impacted water availability and Neolithic cultures. Whereas mid-Holocene drying is commonly attributed to slow insolation reduction and subsequent nonlinear vegetation-atmosphere feedbacks that produce threshold conditions, evidence of trigger events initiating state switching has remained elusive. Here we document a threshold event ca. 4,200 years ago in the Hunshandake Sandy Lands of Inner Mongolia, northern China, associated with groundwater capture by the Xilamulun River. This process initiated a sudden and irreversible region-wide hydrologic event that exacerbated the desertification of the Hunshandake, resulting in post-Humid Period mass migration of northern China's Neolithic cultures. The Hunshandake remains arid and is unlikely, even with massive rehabilitation efforts, to revert back to green conditions.

  13. Surface and bulk modified high capacity layered oxide cathodes with low irreversible capacity loss

    NASA Technical Reports Server (NTRS)

    Manthiram, Arumugam (Inventor); Wu, Yan (Inventor)

    2010-01-01

    The present invention includes compositions, surface and bulk modifications, and methods of making of (1-x)Li[Li.sub.1/3Mn.sub.2/3]O.sub.2.xLi[Mn.sub.0.5-yNi.sub.0.5-yCo.sub.2- y]O.sub.2 cathode materials having an O3 crystal structure with a x value between 0 and 1 and y value between 0 and 0.5, reducing the irreversible capacity loss in the first cycle by surface modification with oxides and bulk modification with cationic and anionic substitutions, and increasing the reversible capacity to close to the theoretical value of insertion/extraction of one lithium per transition metal ion (250-300 mAh/g).

  14. Irreversible Electroporation of Hepatic and Pancreatic Malignancies: Radiologic-Pathologic Correlation.

    PubMed

    Gonzalez-Beicos, Aldo; Venkat, Shree; Songrug, Tanakorn; Poveda, Julio; Garcia-Buitrago, Monica; Poozhikunnath Mohan, Prasoon; Narayanan, Govindarajan

    2015-09-01

    Irreversible electroporation (IRE) is a novel therapy that has shown to be a feasible and promising alternative to conventional ablative techniques when treating tumors near vital structures or blood vessels. The clinical efficacy of IRE has been evaluated using established imaging criteria. This study evaluates the histologic and imaging response of hepatic and pancreatic malignancies that were surgically resected after IRE. In total, 12 lesions ablated with IRE were included, including 3 pancreatic carcinomas, 5 primary tumors of the liver, and 4 metastatic tumors of the liver. The rate of complete response to IRE was 25% based on the histologic evaluation of the resected tumors. Although treatment-related vessel wall changes were noted in several cases in histologic findings, there was no evidence of vascular luminal narrowing or obliteration in any of the specimens. The imaging response to IRE before surgical resection usually resulted in underestimation of disease burden when compared with the histologic response seen on the resected specimens.

  15. Percutaneous Irreversible Electroporation of Locally Advanced Pancreatic Carcinoma Using the Dorsal Approach: A Case Report

    SciTech Connect

    Scheffer, Hester J. Melenhorst, Marleen C. A. M.; Vogel, Jantien A.; Tilborg, Aukje A. J. M. van; Nielsen, Karin Kazemier, Geert; Meijerink, Martijn R.

    2015-06-15

    Irreversible electroporation (IRE) is a novel image-guided ablation technique that is increasingly used to treat locally advanced pancreatic carcinoma (LAPC). We describe a 67-year-old male patient with a 5 cm stage III pancreatic tumor who was referred for IRE. Because the ventral approach for electrode placement was considered dangerous due to vicinity of the tumor to collateral vessels and duodenum, the dorsal approach was chosen. Under CT-guidance, six electrodes were advanced in the tumor, approaching paravertebrally alongside the aorta and inferior vena cava. Ablation was performed without complications. This case describes that when ventral electrode placement for pancreatic IRE is impaired, the dorsal approach could be considered alternatively.

  16. Groundwater sapping as the cause of irreversible desertification of Hunshandake Sandy Lands, Inner Mongolia, northern China.

    PubMed

    Yang, Xiaoping; Scuderi, Louis A; Wang, Xulong; Scuderi, Louis J; Zhang, Deguo; Li, Hongwei; Forman, Steven; Xu, Qinghai; Wang, Ruichang; Huang, Weiwen; Yang, Shixia

    2015-01-20

    In the middle-to-late Holocene, Earth's monsoonal regions experienced catastrophic precipitation decreases that produced green to desert state shifts. Resulting hydrologic regime change negatively impacted water availability and Neolithic cultures. Whereas mid-Holocene drying is commonly attributed to slow insolation reduction and subsequent nonlinear vegetation-atmosphere feedbacks that produce threshold conditions, evidence of trigger events initiating state switching has remained elusive. Here we document a threshold event ca. 4,200 years ago in the Hunshandake Sandy Lands of Inner Mongolia, northern China, associated with groundwater capture by the Xilamulun River. This process initiated a sudden and irreversible region-wide hydrologic event that exacerbated the desertification of the Hunshandake, resulting in post-Humid Period mass migration of northern China's Neolithic cultures. The Hunshandake remains arid and is unlikely, even with massive rehabilitation efforts, to revert back to green conditions. PMID:25561539

  17. Development of Linear Irreversible Thermodynamic Model for Oxidation Reduction Potential in Environmental Microbial System

    PubMed Central

    Cheng, Hong-Bang; Kumar, Mathava; Lin, Jih-Gaw

    2007-01-01

    Nernst equation has been directly used to formulate the oxidation reduction potential (ORP) of reversible thermodynamic conditions but applied to irreversible conditions after several assumptions and/or modifications. However, the assumptions are sometimes inappropriate in the quantification of ORP in nonequilibrium system. We propose a linear nonequilibrium thermodynamic model, called microbial related reduction and oxidation reaction (MIRROR Model No. 1) for the interpretation of ORP in biological process. The ORP was related to the affinities of catabolism and anabolism. The energy expenditure of catabolism and anabolism was directly proportional to overpotential (η), straight coefficient of electrode (LEE), and degree of coupling between catabolism and ORP electrode, respectively. Finally, the limitations of MIRROR Model No. 1 were discussed for expanding the applicability of the model. PMID:17496027

  18. Density fluctuations in irreversible adsorption processes: Hard ellipses in two dimensions

    NASA Astrophysics Data System (ADS)

    Adamczyk, Zbigniew; Weroński, Paweł

    1997-09-01

    Density fluctuations in 2D systems of irreversibly adsorbed particles were studied. Analytical expressions were derived connecting the magnitude of these fluctuations (characterized by the reduced variance σ¯2) with the available surface function φ and the isotropic pair correlation function g0. Limiting expansions in terms of power series of the dimensionless coverage θ were also derived. The range of validity of these expressions was determined by performing numerical simulations based on the random sequential adsorption (RSA) model. Calculations of g0(r), g0(s), φ, and σ¯2 were performed for hard circles and hard ellipses characterized by aspect ratio k=2 and 5. It was deduced that the simulation results can well be accounted for by the theoretical predictions stemming both from the RSA and equilibrium models.

  19. Surface and bulk modified high capacity layered oxide cathodes with low irreversible capacity loss

    DOEpatents

    Manthiram, Arumugam; Wu, Yan

    2010-03-16

    The present invention includes compositions, surface and bulk modifications, and methods of making of (1-x)Li[Li.sub.1/3Mn.sub.2/3]O.sub.2.xLi[Mn.sub.0.5-yNi.sub.0.5-yCo.sub.2- y]O.sub.2 cathode materials having an O3 crystal structure with a x value between 0 and 1 and y value between 0 and 0.5, reducing the irreversible capacity loss in the first cycle by surface modification with oxides and bulk modification with cationic and anionic substitutions, and increasing the reversible capacity to close to the theoretical value of insertion/extraction of one lithium per transition metal ion (250-300 mAh/g).

  20. Fast X-ray microdiffraction techniques for studying irreversible transformations in materials

    PubMed Central

    Kelly, Stephen T.; Trenkle, Jonathan C.; Koerner, Lucas J.; Barron, Sara C.; Walker, Nöel; Pouliquen, Philippe O.; Tate, Mark W.; Gruner, Sol M.; Dufresne, Eric M.; Weihs, Timothy P.; Hufnagel, Todd C.

    2011-01-01

    A pair of techniques have been developed for performing time-resolved X-ray microdiffraction on irreversible phase transformations. In one technique capillary optics are used to focus a high-flux broad-spectrum X-ray beam to a 60 µm spot size and a fast pixel array detector is used to achieve temporal resolution of 55 µs. In the second technique the X-rays are focused with Kirkpatrick–Baez mirrors to achieve a spatial resolution better than 10 µm and a fast shutter is used to provide temporal resolution better than 20 µs while recording the diffraction pattern on a (relatively slow) X-ray CCD camera. Example data from experiments are presented where these techniques are used to study self-propagating high-temperature synthesis reactions in metal laminate foils. PMID:21525656

  1. Transfer of quantum correlations from light to atoms in the case of irreversible evolution

    SciTech Connect

    Gorbachev, V. N.; Trubilko, A. I.

    2010-10-15

    We consider the irreversible dynamics of two two-level atoms that interact with a bipartite broad-band electromagnetic field in an entangled state that forms a heat bath with a quantum correlation. Using Ito's stochastic integration technique, we have derived a kinetic equation for atoms and found their steady state, which turns out to be inseparable and leads to a violation of Bell's inequalities. The application of the atomic state found as a quantum channel for teleportation is considered. We have calculated the channel quality or fidelity that determines the possibilities for using the channel, in particular, characterizes its security. The process of teleportation by means of a quantum channel formed by an entangled heat bath is considered. Comparison of two (atomic and light) channels has shown that they have different properties with regard to separability and identical properties with regard to nonlocality. This means that nonlocality can be completely transferred from light to atoms.

  2. Irreversible response in spin-glasses: An experimental study in amorphous Fe-Mn

    NASA Astrophysics Data System (ADS)

    Yeshurun, Y.; Sompolinsky, H.

    1982-08-01

    The equilibrium and nonequilibrium susceptibilities χe and χne of the spin-glass (Fe0.64Mn0.36)75P16B6Al3 have been measured as functions of temperature (4.2<=T<=80 K) and a cooling field (8 Oe<=H<=2 kOe). A phase transition occurs at a temperature Tc(H) below which the irreversible response Δ(T)~T(χe-χne) appears. Tc(H) decreases from the freezing temperature (Tf=41.6 K) as H0.75+/-0.1. For small τ≡1-TTc(H), Δ behaves as Aτ+Bτ2 with field-dependent coefficients A and B and A(H=0)=0. The results are compared with the predictions of the mean-field theory of spin-glasses.

  3. Onsager's irreversible thermodynamics of the dynamics of transient pores in spherical lipid vesicles.

    PubMed

    Martínez-Balbuena, L; Hernández-Zapata, E; Santamaría-Holek, I

    2015-09-01

    Onsager's irreversible thermodynamics is used to perform a systematic deduction of the kinetic equations governing the opening and collapse of transient pores in spherical vesicles. We show that the edge tension has to be determined from the initial stage of the pore relaxation and that in the final state the vesicle membrane is not completely relaxed, since the surface tension and the pressure difference are about 25% of its initial value. We also show that the pore life-time is controlled by the solution viscosity and its opening is driven by the solution leak-out and the surface tension drop. The final collapse is due to a non-linear interplay between the edge and the surface tensions together with the pressure difference. We also discuss the connection with previous models.

  4. Theophylline and salbutamol improve pulmonary function in patients with irreversible chronic obstructive pulmonary disease.

    PubMed

    Thomas, P; Pugsley, J A; Stewart, J H

    1992-01-01

    To investigate the efficacy of bronchodilators in patients with irreversible chronic obstructive pulmonary disease (COPD), we conducted a double-blind, randomized, four-phase, crossover comparison between placebo, oral theophylline, inhaled salbutamol, and a combination of both drugs in 12 patients with stable COPD (mean age, 63 years) whose increase in forced expiratory volume in 1 s (FEV1) was less than or equal to 15 percent following 200 micrograms of inhaled salbutamol. Patients received two weeks of therapy with each of the test regimens. Both theophylline and salbutamol resulted in statistically significant improvement in FEV1, forced vital capacity (FVC), slow vital capacity (SVC), residual volume (RV), airway resistance (Raw), and maximum expiratory flow rate at 50 percent of vital capacity (V50). In most instances, there were no significant differences between theophylline and salbutamol. Combination therapy produced significantly greater improvement in FEV1, FVC, V50, Raw, and RV than either agent alone. The two drugs interacted in an additive fashion. Neither of the drugs, used singly, significantly reduced the severity or incidence of symptoms. The reduction in dyspnea and wheeze during combination therapy approached statistical significance (p = 0.06) and patient preference was significantly in favor of the combination regimen. None of the active treatments produced significantly more side effects than placebo. We conclude that theophylline and inhaled salbutamol produce significant, and approximately equal, improvement in pulmonary function in patients traditionally classified as suffering from "irreversible" COPD. The combination of theophylline and inhaled salbutamol generally results in additional improvement over that obtained with either drug used alone and this improvement is reflected by reduced symptomatology and treatment preference.

  5. Dynamic scaling in thin-film growth with irreversible step-edge attachment

    NASA Astrophysics Data System (ADS)

    Aarão Reis, F. D. A.

    2010-04-01

    We study dynamic scaling in a model with collective diffusion (CD) of isolated atoms in terraces and irreversible aggregation at step edges. Simulations are performed in two-dimensional substrates with several diffusion to deposition ratios R≡D/F . Data collapse of scaled roughness distributions confirms that this model is in the class of the fourth-order nonlinear growth equation by Villain, Lai, and Das Sarma (VLDS) with negligible finite-size effects, while estimates of scaling exponents show some discrepancies. This result is consistent with the prediction of a recent renormalization group approach and improves previous numerical works on related models. The roughness follows dynamic scaling as W=Lα/R1/2f(ξ/L) , with correlation length ξ=(Rt)1/z , where z is the dynamic exponent. We also propose a limited mobility (LM) model where the incident atom executes up to G steps before a new atom is adsorbed, and irreversibly aggregates at step edges. This model is also shown to belong to the VLDS class. The size of the plateaus in the film surface increases as G1/2 and the lateral correlation scales as G1/2t1/z . The time evolution of the roughness reproduces that of the CD model if an equivalent parameter G˜R2/z is chosen. This suggests the possibility of using LM models with tunable diffusion length to simulate processes with simultaneous diffusion of many atoms. A scaling approach is used to justify exponent values and dynamic relations for both models, including the significant decrease of surface roughness as R or G increases.

  6. Investigating the First-Cycle Irreversibility of Lithium Metal Oxide Cathodes for Li Batteries

    SciTech Connect

    Kang,S.; Yoon , W.; Nam, K.; Yang, X.; Abraham, D.

    2008-01-01

    Layered lithium metal oxide cathodes typically exhibit irreversibility during the first cycle in lithium cells when cycled in conventional voltage ranges (e.g., 3-4.3 V vs. Li+/Li). In this work, we have studied the first-cycle irreversibility of lithium cells containing various layered cathode materials using galvanostatic cycling and in situ synchrotron X-ray diffraction. When cycled between 3.0 and 4.3 V vs. Li+/Li, the cells containing LiCoO2, LiNi0.8Co0.15Al0.05O2, and Li1.048(Ni1/3Co1/3Mn1/3)0.952O2 as cathodes showed initial coulombic efficiencies of 98.0, 87.0, and 88.6%, respectively, at relatively slow current (8 mA/g). However, the 'lost capacity' could be completely recovered by discharging the cells to low voltages (<2 V vs Li+/Li). During this deep discharge, the same cells exhibited voltage plateaus at 1.17, 1.81, and 1.47 V, respectively, which is believed to be associated with formation of a Li2MO2-like phase (M = Ni, Co, Mn) on the oxide particle surface due to very sluggish lithium diffusion in LieMO2 with {var_epsilon}{yields} 1 (i.e., near the end of discharge). The voltage relaxation curve and in situ X-ray diffraction patterns, obtained from a Li/Li1.048(Ni1/3Co1/3Mn1/3)0.952O2 cell, showed that the oxide cathode reversibly returned to its original state [i.e., Li1.048(Ni1/3Co1/3Mn1/3)0.952O2] during relaxation following the deep discharge to achieve 100% cycle efficiency.

  7. Advances pertaining to the pharmacology and interactions of irreversible nonselective monoamine oxidase inhibitors.

    PubMed

    Gillman, Peter Kenneth

    2011-02-01

    Recent advances clarifying the pharmacology and interactions of irreversible nonselective monoamine oxidase inhibitors that have not been considered in depth lately are discussed. These new data elucidate aspects of enzyme inhibition and pharmacokinetic interactions involving amine oxidases, cytochrome P450 enzymes, aminotransferases (transaminases), and decarboxylases (carboxy-lyases) and the effects of tyramine. Phenelzine and tranylcypromine remain widely available, and many publications have data relevant to this review. Their effect on CYP 450 enzymes is less than many newer drugs. Tranylcypromine only inhibits CYP 450 2A6 (selectively and potently). Phenelzine has no reported interactions, but, like isoniazid, weakly and irreversibly inhibits CYP 450 2C19 and 3A4 in vitro. It might possibly be implicated in interactions (as isoniazid is). Phenelzine has some clinically relevant inhibitory effects on amine oxidases, aminotransferases, and decarboxylases, and it lowers pyridoxal phosphate levels. It commonly causes pyridoxal deficiency, weight gain, sedation, and sexual dysfunction, but only rarely causes hepatic damage and failure, or neurotoxicity. The adverse effects and difficulties with monoamine oxidase inhibitors are less than previously believed or estimated, including a lower risk of hypertension, because the tyramine content in foods is now lower. Potent norepinephrine reuptake inhibitors have a strong protective effect against tyramine-induced hypertension. The newly discovered trace amine-associated receptors probably mediate the pressor response. The therapeutic potential of tranylcypromine and L-dopa in depression and Parkinson disease is worthy of reassessment. Monoamine oxidase inhibitors are not used to an extent proportionate with their benefits; medical texts and doctors' knowledge require a major update to reflect the evidence of recent advances.

  8. A facile route for irreversible bonding of plastic-PDMS hybrid microdevices at room temperature.

    PubMed

    Tang, Linzhi; Lee, Nae Yoon

    2010-05-21

    Plastic materials do not generally form irreversible bonds with poly(dimethylsiloxane) (PDMS) regardless of oxygen plasma treatment and a subsequent thermal process. In this paper, we perform plastic-PDMS bonding at room temperature, mediated by the formation of a chemically robust amine-epoxy bond at the interfaces. Various plastic materials, such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polyimide (PI), and poly(ethylene terephthalate) (PET) were adopted as choices for plastic materials. Irrespective of the plastic materials used, the surfaces were successfully modified with amine and epoxy functionalities, confirmed by the surface characterizations such as water contact angle measurements and X-ray photoelectron spectroscopy (XPS), and chemically robust and irreversible bonding was successfully achieved within 1 h at room temperature. The bonding strengths of PDMS with PMMA and PC sheets were measured to be 180 and 178 kPa, respectively, and their assemblies containing microchannel structures endured up to 74 and 84 psi (510 and 579 kPa) of introduced compressed air, respectively, without destroying the microdevices, representing a robust and highly stable interfacial bonding. In addition to microchannel-molded PDMS bonded with flat plastic substrates, microchannel-embossed plastics were also bonded with a flat PDMS sheet, and both types of bonded assemblies displayed sufficiently robust bonding, tolerating an intense influx of liquid whose per-minute injection volume was nearly 1000 to 2000 times higher than the total internal volume of the microchannel used. In addition to observing the bonding performance, we also investigated the potential of surface amine and epoxy functionalities as durable chemical adhesives by observing their storage-time-dependent bonding performances.

  9. Selective and Irreversible Inhibitors of Aphid Acetylcholinesterases: Steps Toward Human-Safe Insecticides

    PubMed Central

    Pang, Yuan-Ping; Singh, Sanjay K.; Gao, Yang; Lassiter, T. Leon; Mishra, Rajesh K.; Zhu, Kun Yan; Brimijoin, Stephen

    2009-01-01

    Aphids, among the most destructive insects to world agriculture, are mainly controlled by organophosphate insecticides that disable the catalytic serine residue of acetylcholinesterase (AChE). Because these agents also affect vertebrate AChEs, they are toxic to non-target species including humans and birds. We previously reported that a cysteine residue (Cys), found at the AChE active site in aphids and other insects but not mammals, might serve as a target for insect-selective pesticides. However, aphids have two different AChEs (termed AP and AO), and only AP-AChE carries the unique Cys. The absence of the active-site Cys in AO-AChE might raise concerns about the utility of targeting that residue. Herein we report the development of a methanethiosulfonate-containing small molecule that, at 6.0 µM, irreversibly inhibits 99% of all AChE activity extracted from the greenbug aphid (Schizaphis graminum) without any measurable inhibition of the human AChE. Reactivation studies using β-mercaptoethanol confirm that the irreversible inhibition resulted from the conjugation of the inhibitor to the unique Cys. These results suggest that AO-AChE does not contribute significantly to the overall AChE activity in aphids, thus offering new insight into the relative functional importance of the two insect AChEs. More importantly, by demonstrating that the Cys-targeting inhibitor can abolish AChE activity in aphids, we can conclude that the unique Cys may be a viable target for species-selective agents to control aphids without causing human toxicity and resistance problems. PMID:19194505

  10. Sorption irreversibility of 1,4-dichlorobenzene in two natural organic matter-rich geosorbents

    SciTech Connect

    Sander, M.; Pignatello, J.J.

    2009-03-15

    Hysteresis, a frequently observed phenomenon in sorption studies, is inconsistent with the key assumption of sorption reversibility in most fate and bioavailability models. Therefore, a study of the underlying causes of hysteresis is essential. Carbon-radiolabeled 1,4-dichlorobenzene (DCB) isotope tracer exchange was carried out at select points along the isotherms of DCB in a brown coal and a peat soil, holding total DCB concentration constant. Tracer exchange was performed both in the forward (sorption) and reverse (desorption) directions at the bulk sorption points and in the desorption direction at the corresponding bulk desorption points. Bulk DCB isotherms showed concentration-dependent hysteresis. However, tracer reequilibration in all cases was consistent with free exchange between sorbed and aqueous-phase molecules. These results rule out common experimental artifacts and demonstrate that sorption of bulk DCB is truly hysteretic (i.e., irreversible). The differences in rates between bulk and tracer sorption and desorption are consistent with the coupling of bulk DCB diffusion to other processes that retard equilibration, which we assign to matrix swelling or shrinking. Hysteresis is attributed to matrix deformation-specifically, to inelastic expansion and creation of voids accommodating sorbate molecules in the matrix, which leads to enhanced affinity in the desorption step. Comparing the results to previous results for naphthalene in the coal, we find that irreversible effects are similar for DCB and naphthalene in the coal but differ for DCB between the two sorbents. An explanation based on the different physical properties of these sorbents is provided. Solid-phase extraction of equilibrated DCB with Tenax revealed a highly desorption-resistant fraction. While too small to account for the observed hysteresis, this fraction may represent molecules that become trapped as the matrix collapses and simultaneously stiffens during abrupt desorption.

  11. Two studies of nonlinear processes in irreversible thermodynamics. Final report, May 1, 1989--April 30, 1992

    SciTech Connect

    Kestin, J.

    1992-07-01

    The investigation dealt with two lines of research into two well-defined problems of engineering science: a study of two-phase flow and of nonelastic deformations in structural solids. Both topics fall into the broad field of nonlinear irreversible processes. The study of two-phase flow resulted in a complete topological analysis of the canonical mathematical model of one-dimensional flow of a mixture of two phases, now predominantly used in industry, especially the nuclear industry. The topological analysis is confronted with the practice of discretizing the analytic model for the purpose of formulating a numerical computer code. It is shown that in the presence of singular points in the phase space of the differential equations of the model there occur spurious numerical solutions. Such solutions may contain segments which are correct approximations to the exact trajectory, but always include branches which are totally false and misleading. The topological method allows the operator to formulate a subroutine which eliminates spurious solutions. The study of inelastic deformations, i.e., of irreversible processes in structural solids provided a consistent presentation of the local-state approximation erroneously called the method of local equilibrium in the literature. The key concept which impedes the correct use of thermodynamics in this field is the definition of a measurable entropy of a nonequilibrium state. The local state approximation solves this problem by assigning to a nonequilibrium state n the entropy of the accompanying equilibrium state e. The two states, n and e, are linked by having the same values of a specified set of extensive properties. The same principle settles the comparison between the intensive properties of n and e, which are different.

  12. Liver-Directed Irreversible Electroporation Therapy: Longitudinal Efficacy Studies in a Rat Model of Hepatocellular Carcinoma

    PubMed Central

    Guo, Yang; Zhang, Yue; Klein, Rachel; Nijm, Grace M.; Sahakian, Alan V.; Omary, Reed A.; Yang, Guang-Yu; Larson, Andrew C.

    2009-01-01

    Irreversible electroporation (IRE) is an innovative local-regional therapy that involves delivery of intense electrical pulses to induce nano-scale cell membrane defects for tissue ablation. The purpose of this study was to investigate the feasibility of using irreversible electroporation as a liver-directed ablation technique for the treatment of hepatocellular carcinoma (HCC) in the N1-S1 rodent model. N1-S1 rat hepatoma was grown in 30 Sprague-Dawley rats; these animals were divided into treatment and control groups. For treatment groups, IRE electrodes were inserted and 8 100 µs 2500V pulses applied to ablate the targeted tumor tissues. For both treatment and control groups (6 rats/group), MRI scans were performed at base-line and 15-day follow-up intervals to measure tumor sizes (1D maximum diameter, Dmax, and estimated 2D cross-sectional area, Cmax) to determine longitudinal outcomes based upon observed size changes. Additional groups of treated animals were sacrificed at 1, 3, and 7-day intervals post-therapy for pathology assessment of treatment response. MR images demonstrated significant tumor size reductions within 15 days post-therapy (32±31% Dmax and 52±39% Cmax decreases compared to 110±35% Dmax and 286±125% Cmax increases for untreated tumors). Pathology correlation studies showed a clear progression from poorly differentiated viable HCC tissues pre-therapy to extensive tumor necrosis and complete regression in 9 out of 10 treated rats 7–15 days after treatment. Our findings suggest that IRE was effective for targeted ablation of liver tumors in the N1-S1 rodent model; IRE may offer a promising new approach for liver-directed treatment of HCC. PMID:20124486

  13. Differences between reversible (self-association) and irreversible aggregation of rHuG-CSF in carbohydrate and polyol formulations.

    PubMed

    Pavišić, Renata; Dodig, Ivana; Horvatić, Anita; Mijić, Lucija; Sedić, Mirela; Linarić, Maša Rajić; Sovulj, Ita Gruić; Preočanin, Tajana; Krajačić, Mirjana Bukvić; Cindrić, Mario

    2010-11-01

    Severe immunogenic and other debilitating human disorders potentially induced by protein aggregates have brought this phenomenon into the focus of biopharmaceutical science over the past decade. Depending on its driving forces, the process induced in the model protein rHuG-CSF may be either reversible or irreversible, resulting in the assembly of self-associated protein species or irreversible aggregates of various final morphologies. The aim of our work was to investigate the correlation between irreversible and reversible aggregation and the protective effect of non-specific formulation stabilisers, selected from the group of carbohydrates and polyols including trehalose, xylitol, cellobiitol, turanose, cellobiose, leucrose, lactitol, lyxose, and sorbitol, against both irreversible protein aggregation and reversible self-association processes of the rHuG-CSF. The formation of irreversible aggregates was thermally induced and evaluated using differential scanning calorimetry and size-exclusion chromatography. As opposed to the irreversible aggregation process, the process of self-association was induced by the agitation experiment by directly augmenting the protein solution contact surfaces. Absence of statistical connectivity between different stabilisers' ability to inhibit self-association or aggregation reactions indicates that these are two distinct physicochemical processes with different formulation stabilizing outcomes. Reaction mechanism of thermally induced aggregation observed in the study was in line with published literature data, while the reaction mechanism for self-association process was postulated. The postulate has been verified experimentally by isothermal calorimetry and agitation set of experiments conducted after size-exclusion chromatography and asymmetrical flow field-flow fractionation separation of monomeric, dimeric, trimeric, oligomeric, and large self-associated forms detected on multi-angle light scattering, fluorescence, UV, and

  14. Application of exergetic sustainable index to the quantum irreversible Diesel refrigerator cycles for 1D box system

    NASA Astrophysics Data System (ADS)

    Açıkkalp, Emin; Caner, Necmettin

    2015-04-01

    In this paper, an irreversible quantum Diesel refrigerator for a 1D-box system is described and analyzed. The exergetic sustainability index that is the rate of the exergy output from the system to the total exergetic losses including exergy destruction and exergy loss from the system is applied for the first time to an irreversible quantum engine. Other thermodynamic parameters including work input, cooling load, exergy destruction, COP and exergy efficiency are investigated according to the cycle temperatures and numerical results are presented.

  15. Effect of electrode density on cycle performance and irreversible capacity loss for natural graphite anode in lithium ion batteries

    SciTech Connect

    Shim, Joongpyo; Striebel, Kathryn A.

    2002-12-02

    The effect of electrode thickness and density for unpressed and pressed natural graphite electrodes were studied using electrochemical characterization. Pressing the graphite electrode decreases the reversible capacity and the irreversible capacity loss during formation. As electrode density increased, the capacity retention at high rate increased until 0.9g/cm{sup 3}, and then decreased. The cycle performances of the pressed graphite electrodes were more stable than the unpressed one. Pressing graphite electrode affected on its electrochemical characterization such as irreversible capacity loss, high rate cycling and cycle performance.

  16. Irreversible simulated tempering algorithm with skew detailed balance conditions: a learning method of weight factors in simulated tempering

    NASA Astrophysics Data System (ADS)

    Sakai, Yuji; Hukushima, Koji

    2016-09-01

    Recent numerical studies concerning simulated tempering algorithm without the detailed balance condition are reviewed and an irreversible simulated tempering algorithm based on the skew detailed balance condition is described. A method to estimate weight factors in simulated tempering by sequentially implementing the irreversible simulated tempering algorithm is studied in comparison with the conventional simulated tempering algorithm satisfying the detailed balance condition. It is found that the total amount of Monte Carlo steps for estimating the weight factors is successfully reduced by applying the proposed method to an two-dimensional ferromagnetic Ising model.

  17. Effect of 5. 3-GeV Pb-ion irradiation on irreversible magnetization in Y-Ba-Cu-O crystals

    SciTech Connect

    Konczykowski, M.; Rullier-Albenque, F. ); Yacoby, E.R.; Shaulov, A.; Yeshurun, Y. ); Lejay, P. )

    1991-10-01

    We report a dramatic change in the irreversibility line of Y-Ba-Cu-O crystals after irradiation with Pb ions. Near the transition temperature, following irradiation, the irreversibility temperature increases and the curvature of the irreversibility line changes sign. These changes are accompanied by a strong enhancement of critical current density and a decrease in flux creep rate. Pb irradiation induces damage in the form of amorphous tracks which penetrate throughout the thickness of the sample. We maintain that these defects are most efficient in terms of flux trapping and are responsible for the observed changes in irreversible magnetic features in the irradiated sample.

  18. Optimum Criteria on the Performance of an Irreversible Braysson Heat Engine Based on the new Thermoeconomic Approach

    NASA Astrophysics Data System (ADS)

    Tyagi, Sudhir K.; Zhou, Yinghui; Chen, Jincan

    2004-03-01

    An irreversible cycle model of a Braysson heat engine operating between two heat reservoirs is used to investigate the thermoeconomic performance of the cycle affected by the finite-rate heat transfer between the working fluid and the heat reservoirs, heat leak loss from the heat source to the ambient and the irreversibility within the cycle. The thermoeconomic objective function, defined as the total cost per unit power output, is minimized with respect to the cycle temperatures along with the isobaric temperature ratio for a given set of operating parameters. The objective function is found to be an increasing function of the internal irreversibility parameter, economic parameters and the isobaric temperature ratio. On the other hand, there exist the optimal values of the state point temperatures, power output and thermal efficiency at which the objective function attains its minimum for a typical set of operating parameters. Moreover, the objective function and the corresponding power output are also plotted against the state point temperature and thermal efficiency for a different set of operating parameters. The optimally operating regions of these important parameters in the cycle are also determined. The results obtained here may provide some useful criteria for the optimal design and performance improvements, from the point of view of economics as well as from the point of view of thermodynamics of an irreversible Braysson heat engine cycle and other similar cycles as well.

  19. Characteristics of meso-particles formed in coagulation process causing irreversible membrane fouling in the coagulation-microfiltration water treatment.

    PubMed

    Ding, Q; Yamamura, H; Murata, N; Aoki, N; Yonekawa, H; Hafuka, A; Watanabe, Y

    2016-09-15

    In coagulation-membrane filtration water treatment processes, it is still difficult to determine the optimal coagulation condition to minimize irreversible membrane fouling. In microfiltration (MF), meso-particles (i.e., 20 nm-0.5 μm) are thought to play an important role in irreversible membrane fouling, especially their characteristics of particle number (PN) and zeta potential (ZP). In this study, a new nanoparticle tracker combined a high-output violet laser with a microscope was developed to identify the physicochemical characteristics of these microscopic and widely dispersed meso-particles. The effects of pH and coagulant dose on ZP and PN of micro-particles (i.e., >0.5 μm) and meso-particles were investigated, and then coagulation-MF tests were conducted. As the result, irreversible membrane fouling was best controlled for both types of membranes, while meso-particle ZP approached zero at around pH 5.5 for both types of natural water. Since PN was greatest under these conditions, ZP is more important in determining the extent of irreversible membrane fouling than PN. However, the acidic condition to neutralize meso-particles is not suitable for actual operation, as considering residual aluminum concentration, pipe corrosion, and chlorination efficiency. It is therefore necessary to investigate coagulants or other methods for the appropriate modification of meso-particle characteristics. PMID:27262117

  20. Characteristics of meso-particles formed in coagulation process causing irreversible membrane fouling in the coagulation-microfiltration water treatment.

    PubMed

    Ding, Q; Yamamura, H; Murata, N; Aoki, N; Yonekawa, H; Hafuka, A; Watanabe, Y

    2016-09-15

    In coagulation-membrane filtration water treatment processes, it is still difficult to determine the optimal coagulation condition to minimize irreversible membrane fouling. In microfiltration (MF), meso-particles (i.e., 20 nm-0.5 μm) are thought to play an important role in irreversible membrane fouling, especially their characteristics of particle number (PN) and zeta potential (ZP). In this study, a new nanoparticle tracker combined a high-output violet laser with a microscope was developed to identify the physicochemical characteristics of these microscopic and widely dispersed meso-particles. The effects of pH and coagulant dose on ZP and PN of micro-particles (i.e., >0.5 μm) and meso-particles were investigated, and then coagulation-MF tests were conducted. As the result, irreversible membrane fouling was best controlled for both types of membranes, while meso-particle ZP approached zero at around pH 5.5 for both types of natural water. Since PN was greatest under these conditions, ZP is more important in determining the extent of irreversible membrane fouling than PN. However, the acidic condition to neutralize meso-particles is not suitable for actual operation, as considering residual aluminum concentration, pipe corrosion, and chlorination efficiency. It is therefore necessary to investigate coagulants or other methods for the appropriate modification of meso-particle characteristics.

  1. Tracking inorganic foulants irreversibly accumulated on low-pressure membranes for treating surface water.

    PubMed

    Yamamura, Hiroshi; Kimura, Katsuki; Higuchi, Kumiko; Watanabe, Yoshimasa; Ding, Qing; Hafuka, Akira

    2015-12-15

    While low-pressure membrane filtration processes (i.e., microfiltration and ultrafiltration) can offer precise filtration than sand filtration, they pose the problem of reduced efficiency due to membrane fouling. Although many studies have examined membrane fouling by organic substances, there is still not enough data available concerning membrane fouling by inorganic substances. The present research investigated changes in the amounts of inorganic components deposited on the surface of membrane filters over time using membrane specimens sampled thirteen times at arbitrary time intervals during pilot testing in order to determine the mechanism by which irreversible fouling by inorganic substances progresses. The experiments showed that the inorganic components that primarily contribute to irreversible fouling vary as filtration continues. It was discovered that, in the initial stage of operation, the main membrane-fouling substance was iron, whereas the primary membrane-fouling substances when operation finished were manganese, calcium, and silica. The amount of iron accumulated on the membrane increased up to the thirtieth day of operation, after which it reached a steady state. After the accumulation of iron became static, subsequent accumulation of manganese was observed. The fact that the removal rates of these inorganic components also increased gradually shows that the size of the exclusion pores of the membrane filter narrows as operation continues. Studying particle size distributions of inorganic components contained in source water revealed that while many iron particles are approximately the same size as membrane pores, the fraction of manganese particles slightly smaller than the pores in diameter was large. From these results, it is surmised that iron particles approximately the same size as the pores block them soon after the start of operation, and as the membrane pores narrow with the development of fouling, they become further blocked by manganese

  2. Irreversible thermochromic response of RF sputtered nanocrystalline BaWO4 films for smart window applications

    NASA Astrophysics Data System (ADS)

    Anil Kumar, C.; Santhosh Kumar, T.; Pamu, D.

    2015-10-01

    We report irreversible thermochromic behaviour of BaWO4 (BWO) films for the first time. BWO films have been deposited at different substrate temperatures (RT, 200, 400, 600 and 800 °C) using RF magnetron sputtering in pure argon plasma. BWO films deposited at 800 °C exhibit crystalline nature. Also, BWO films deposited in the temperature range of 400 - 600 °C exhibit WO3 as a secondary phase and its weight percentage decreases with an increase in deposition temperature, whereas the films deposited at 800 °C exhibited pure tetragonal phase. FESEM images revealed that as the average particle sizes of the films are higher as compared with the thickness of the films and is explained based on Avrami type nucleation and growth. The transmittance of the films decreases with an increase in deposition temperature up to 600 °C and increases thereafter. Films deposited at 600 °C show ≤ 20% transmittance, looking at the films deposited at room temperature and 800 °C exhibits 90 and 70%, respectively. The refractive index and extinction coefficient of the films show profound dependence on crystallinity and packing density. The optical bandgap of BWO films increases significantly with an increase in O2% during the deposition. The optical bandgap of the BWO films deposited at different temperatures in pure argon plasma, are in the range of 3.7 to 3.94 eV whereas the films deposited at 600 °C under different O2 plasma are in the range of 3.6 - 4.5 eV. The formations of colour centres are associated with the oxygen vacancies, which are clearly seen from the optical bandgap studies. The observed irreversible thermochromic behaviour in BWO films is attributed to the presence of oxygen vacancies that arises due to the electrons trapped at oxygen vacancies causing an inter valence charge transfer of W5+ to W6+ and is confirmed through the change in the optical density (ΔOD). Further, the Raman spectra are being used to quantify the presence of oxygen vacancies and the

  3. Reduction in mitochondrial potential constitutes an early irreversible step of programmed lymphocyte death in vivo

    PubMed Central

    1995-01-01

    In a number of experimental systems in which lymphocyte depletion was induced by apoptosis-inducing manipulations, no apoptotic morphology and ladder-type DNA fragmentation were detected among freshly isolated peripheral lymphocytes ex vivo. Here we report that one alteration that can be detected among splenocytes stimulated with lymphocyte-depleting doses of dexamethasone (DEX) in vivo is a reduced uptake of 3,3'dihexyloxacarbocyanine iodide (DiOC6[3]), a fluorochrome which incorporates into cells dependent upon their mitochondrial transmembrane potential (delta psi m). In contrast, ex vivo isolated splenocytes still lacked established signs of programmed cell death (PCD):DNA degradation into high or low molecular weight fragments, ultrastructural changes of chromatin arrangement and endoplasmatic reticulum, loss in viability, or accumulation of intracellular peroxides. Moreover, no changes in cell membrane potential could be detected. A reduced delta psi m has been observed in response to different agents inducing lymphoid cell depletion in vivo (superantigen and glucocorticoids [GC]), in mature T and B lymphocytes, as well as their precursors. DEX treatment in vivo, followed by cytofluorometric purification of viable delta psi mlow splenic T cells ex vivo, revealed that this fraction of cells is irreversibly committed to undergoing DNA fragmentation. Immediately after purification neither delta psi mlow, nor delta psi mhigh cells, exhibit detectable DNA fragmentation. However, after short-term culture (37 degrees C, 1 h) delta psi mlow cells show endonucleolysis, followed by cytolysis several hours later. Incubation of delta psi mlow cells in the presence of excess amount of the GC receptor antagonist RU38486 (which displaces DEX from the GC receptor), cytokines that inhibit DEX-induced cell death, or cycloheximide fails to prevent cytolysis. The antioxidant, N- acetylcysteine, as well as linomide, an agent that effectively inhibits DEX or superantigen

  4. High-frequency irreversible electroporation (H-FIRE) for non-thermal ablation without muscle contraction

    PubMed Central

    2011-01-01

    Background Therapeutic irreversible electroporation (IRE) is an emerging technology for the non-thermal ablation of tumors. The technique involves delivering a series of unipolar electric pulses to permanently destabilize the plasma membrane of cancer cells through an increase in transmembrane potential, which leads to the development of a tissue lesion. Clinically, IRE requires the administration of paralytic agents to prevent muscle contractions during treatment that are associated with the delivery of electric pulses. This study shows that by applying high-frequency, bipolar bursts, muscle contractions can be eliminated during IRE without compromising the non-thermal mechanism of cell death. Methods A combination of analytical, numerical, and experimental techniques were performed to investigate high-frequency irreversible electroporation (H-FIRE). A theoretical model for determining transmembrane potential in response to arbitrary electric fields was used to identify optimal burst frequencies and amplitudes for in vivo treatments. A finite element model for predicting thermal damage based on the electric field distribution was used to design non-thermal protocols for in vivo experiments. H-FIRE was applied to the brain of rats, and muscle contractions were quantified via accelerometers placed at the cervicothoracic junction. MRI and histological evaluation was performed post-operatively to assess ablation. Results No visual or tactile evidence of muscle contraction was seen during H-FIRE at 250 kHz or 500 kHz, while all IRE protocols resulted in detectable muscle contractions at the cervicothoracic junction. H-FIRE produced ablative lesions in brain tissue that were characteristic in cellular morphology of non-thermal IRE treatments. Specifically, there was complete uniformity of tissue death within targeted areas, and a sharp transition zone was present between lesioned and normal brain. Conclusions H-FIRE is a feasible technique for non-thermal tissue

  5. Magnetic Resonance Measurement of Turbulent Kinetic Energy for the Estimation of Irreversible Pressure Loss in Aortic Stenosis

    PubMed Central

    Dyverfeldt, Petter; Hope, Michael D.; Tseng, Elaine E.; Saloner, David

    2013-01-01

    OBJECTIVES The authors sought to measure the turbulent kinetic energy (TKE) in the ascending aorta of patients with aortic stenosis and to assess its relationship to irreversible pressure loss. BACKGROUND Irreversible pressure loss caused by energy dissipation in post-stenotic flow is an important determinant of the hemodynamic significance of aortic stenosis. The simplified Bernoulli equation used to estimate pressure gradients often misclassifies the ventricular overload caused by aortic stenosis. The current gold standard for estimation of irreversible pressure loss is catheterization, but this method is rarely used due to its invasiveness. Post-stenotic pressure loss is largely caused by dissipation of turbulent kinetic energy into heat. Recent developments in magnetic resonance flow imaging permit noninvasive estimation of TKE. METHODS The study was approved by the local ethics review board and all subjects gave written informed consent. Three-dimensional cine magnetic resonance flow imaging was used to measure TKE in 18 subjects (4 normal volunteers, 14 patients with aortic stenosis with and without dilation). For each subject, the peak total TKE in the ascending aorta was compared with a pressure loss index. The pressure loss index was based on a previously validated theory relating pressure loss to measures obtainable by echocardiography. RESULTS The total TKE did not appear to be related to global flow patterns visualized based on magnetic resonance–measured velocity fields. The TKE was significantly higher in patients with aortic stenosis than in normal volunteers (p < 0.001). The peak total TKE in the ascending aorta was strongly correlated to index pressure loss (R2 = 0.91). CONCLUSIONS Peak total TKE in the ascending aorta correlated strongly with irreversible pressure loss estimated by a well-established method. Direct measurement of TKE by magnetic resonance flow imaging may, with further validation, be used to estimate irreversible pressure loss

  6. Reversible and irreversible emergence of chiroptical signals in J-aggregates of achiral 4-sulfonatophenyl substituted porphyrins: intrinsic chirality vs. chiral ordering in the solution.

    PubMed

    Arteaga, Oriol; El-Hachemi, Zoubir; Canillas, Adolf; Crusats, Joaquim; Rovira, Meritxell; Ribó, Josep M

    2016-09-18

    Mueller matrix polarimetry distinguishes the different origins of the reversible and irreversible chiroptical effects emerging in stirred solutions of J-aggregate nanoparticles: the reversible effect is due to an anisotropic ordering in the solution and the irreversible one is due to a bias from the racemic composition of intrinsically chiral structures.

  7. The effect of small intestine heterogeneity on irreversible electroporation treatment planning.

    PubMed

    Phillips, Mary

    2014-09-01

    Nonthermal irreversible electroporation (NTIRE) is an ablation modality that utilizes microsecond electric fields to produce nanoscale defects in the cell membrane. This results in selective cell death while preserving all other molecules, including the extracellular matrix. Here, finite element analysis and experimental results are utilized to examine the effect of NTIRE on the small intestine due to concern over collateral damage to this organ during NTIRE treatment of abdominal cancers. During previous studies, the electrical treatment parameters were chosen based on a simplified homogeneous tissue model. The small intestine, however, has very distinct layers, and a more realistic model is needed to further develop this technology for precise clinical applications. This study uses a two-dimensional finite element solution of the Laplace and heat conduction equations to investigate how small intestine heterogeneities affect the electric field and temperature distribution. Experimental results obtained by applying NTIRE to the rat small intestine in vivo support the heterogeneous effect of NTIRE on the tissue. The numerical modeling indicates that the electroporation parameters chosen for this study avoid thermal damage to the tissue. This is supported by histology obtained from the in vivo study, which showed preservation of extracellular structures. The finite element model also indicates that the heterogeneous structure of the small intestine has a significant effect on the electric field and volume of cell ablation during electroporation and could have a large impact on the extent of treatment. The heterogeneous nature of the tissue should be accounted for in clinical treatment planning.

  8. Vertical distribution of overpotentials and irreversible charge losses in lithium ion battery electrodes.

    PubMed

    Klink, Stefan; Schuhmann, Wolfgang; La Mantia, Fabio

    2014-08-01

    Porous lithium ion battery electrodes are characterized using a vertical distribution of cross-currents. In an appropriate simplification, this distribution can be described by a transmission line model (TLM) consisting of infinitely thin electrode layers. To investigate the vertical distribution of currents, overpotentials, and irreversible charge losses in a porous graphite electrode in situ, a multi-layered working electrode (MWE) was developed as the experimental analogue of a TLM. In this MWE, each layer is in ionic contact but electrically insulated from the other layers by a porous separator. It was found that the negative graphite electrodes get lithiated and delithiated stage-by-stage and layer-by-layer. Several mass-transport- as well as non-mass-transport-limited processes could be identified. Local current densities can reach double the average, especially on the outermost layer at the beginning of each intercalation stage. Furthermore, graphite particles close to the counter electrode act as "electrochemical sieve" reducing the impurities present in the electrolyte such as water.

  9. Optimal thermoeconomic performance of an irreversible regenerative ferromagnetic Ericsson refrigeration cycle

    NASA Astrophysics Data System (ADS)

    Xu, Zhichao; Guo, Juncheng; Lin, Guoxing; Chen, Jincan

    2016-07-01

    On the basis of the Langevin theory of classical statistical mechanics, the magnetization, entropy, and iso-field heat capacity of ferromagnetic materials are analyzed and their mathematical expressions are derived. An irreversible regenerative Ericsson refrigeration cycle by using a ferromagnetic material as the working substance is established, in which finite heat capacity rates of low and high temperature reservoirs, non-perfect regenerative heat of the refrigeration cycle, additional regenerative heat loss, etc. are taken into account. Based on the regenerative refrigeration cycle model, a thermoeconomic function is introduced as one objective function and optimized with respect to the temperatures of the working substance in the two iso-thermal processes. By means of numerical calculation, the effects of the effective factor of the heat exchangers in high/low temperature reservoir sides, efficiency of the regenerator, heat capacity rate of the low temperature reservoir, and applied magnetic field on the optimal thermoeconomic function as well as the corresponding cooling rate and coefficient of performance are revealed. The results obtained in this paper can provide some theoretical guidance for the optimal design of actual regenerative magnetic refrigerator cycle.

  10. Local equilibrium and the second law of thermodynamics for irreversible systems with thermodynamic inertia

    SciTech Connect

    Glavatskiy, K. S.

    2015-10-28

    Validity of local equilibrium has been questioned for non-equilibrium systems which are characterized by delayed response. In particular, for systems with non-zero thermodynamic inertia, the assumption of local equilibrium leads to negative values of the entropy production, which is in contradiction with the second law of thermodynamics. In this paper, we address this question by suggesting a variational formulation of irreversible evolution of a system with non-zero thermodynamic inertia. We introduce the Lagrangian, which depends on the properties of the normal and the so-called “mirror-image” systems. We show that the standard evolution equations, in particular, the Maxwell-Cattaneo-Vernotte equation, can be derived from the variational procedure without going beyond the assumption of local equilibrium. We also argue that the second law of thermodynamics in non-equilibrium should be understood as a consequence of the variational procedure and the property of local equilibrium. For systems with instantaneous response this leads to the standard requirement of the local instantaneous entropy production being always positive. However, if a system is characterized by delayed response, the formulation of the second law of thermodynamics should be altered. In particular, the quantity, which is always positive, is not the instantaneous entropy production, but the entropy production averaged over a proper time interval.

  11. Local equilibrium and the second law of thermodynamics for irreversible systems with thermodynamic inertia.

    PubMed

    Glavatskiy, K S

    2015-10-28

    Validity of local equilibrium has been questioned for non-equilibrium systems which are characterized by delayed response. In particular, for systems with non-zero thermodynamic inertia, the assumption of local equilibrium leads to negative values of the entropy production, which is in contradiction with the second law of thermodynamics. In this paper, we address this question by suggesting a variational formulation of irreversible evolution of a system with non-zero thermodynamic inertia. We introduce the Lagrangian, which depends on the properties of the normal and the so-called "mirror-image" systems. We show that the standard evolution equations, in particular, the Maxwell-Cattaneo-Vernotte equation, can be derived from the variational procedure without going beyond the assumption of local equilibrium. We also argue that the second law of thermodynamics in non-equilibrium should be understood as a consequence of the variational procedure and the property of local equilibrium. For systems with instantaneous response this leads to the standard requirement of the local instantaneous entropy production being always positive. However, if a system is characterized by delayed response, the formulation of the second law of thermodynamics should be altered. In particular, the quantity, which is always positive, is not the instantaneous entropy production, but the entropy production averaged over a proper time interval.

  12. A Parametric Study Delineating Irreversible Electroporation from Thermal Damage Based on a Minimally Invasive Intracranial Procedure

    PubMed Central

    2011-01-01

    Background Irreversible electroporation (IRE) is a new minimally invasive technique to kill undesirable tissue in a non-thermal manner. In order to maximize the benefits from an IRE procedure, the pulse parameters and electrode configuration must be optimized to achieve complete coverage of the targeted tissue while preventing thermal damage due to excessive Joule heating. Methods We developed numerical simulations of typical protocols based on a previously published computed tomographic (CT) guided in vivo procedure. These models were adapted to assess the effects of temperature, electroporation, pulse duration, and repetition rate on the volumes of tissue undergoing IRE alone or in superposition with thermal damage. Results Nine different combinations of voltage and pulse frequency were investigated, five of which resulted in IRE alone while four produced IRE in superposition with thermal damage. Conclusions The parametric study evaluated the influence of pulse frequency and applied voltage on treatment volumes, and refined a proposed method to delineate IRE from thermal damage. We confirm that determining an IRE treatment protocol requires incorporating all the physical effects of electroporation, and that these effects may have significant implications in treatment planning and outcome assessment. The goal of the manuscript is to provide the reader with the numerical methods to assess multiple-pulse electroporation treatment protocols in order to isolate IRE from thermal damage and capitalize on the benefits of a non-thermal mode of tissue ablation. PMID:21529373

  13. In vitro and numerical support for combinatorial irreversible electroporation and electrochemotherapy glioma treatment.

    PubMed

    Neal, R E; Rossmeisl, J H; D'Alfonso, V; Robertson, J L; Garcia, P A; Elankumaran, S; Davalos, R V

    2014-03-01

    Irreversible electroporation (IRE) achieves targeted volume non-thermal focal ablation using a series of brief electric pulses to kill cells by disrupting membrane integrity. Electrochemotherapy (ECT) uses lower numbers of sub-lethal electric pulses to disrupt membranes for improved drug uptake. Malignant glioma (MG) brain tumors are difficult to treat due to diffuse peripheral margins into healthy neural tissue. Here, in vitro experimental data and numerical simulations investigate the feasibility for IRE-relevant pulse protocols with adjuvant ECT drugs to enhance MG treatment. Cytotoxicity curves were produced on two glioma cell lines in vitro at multiple pulse strengths and drug doses with Bleomycin or Carboplatin. Pulses alone increased cytotoxicity with higher pulse numbers and strengths, reaching >90% by 800 V/cm with 90 pulses. Chemotherapeutic addition increased cytotoxicity by >50% for 1 ng/mL concentrations of either drug relative to 80 pulses alone with J3T cells at electric fields ≥400 V/cm. In addition to necrosis, transmission electron microscopy visualizes apoptotic morphological changes and Hoescht 33342 staining shows apoptotic cell fractions varying with electric field and drug dose relative to controls. Numerically simulated treatment volumes in a canine brain show IRE combined with ECT expands therapeutic volume by 2.1-3.2 times compared to IRE alone. PMID:24165928

  14. Pathology of non-thermal irreversible electroporation (N-TIRE)-induced ablation of the canine brain.

    PubMed

    Rossmeisl, John H; Garcia, Paulo A; Roberston, John L; Ellis, Thomas L; Davalos, Rafael V

    2013-01-01

    This study describes the neuropathologic features of normal canine brain ablated with non-thermal irreversible electroporation (N-TIRE). The parietal cerebral cortices of four dogs were treated with N-TIRE using a dose-escalation protocol with an additional dog receiving sham treatment. Animals were allowed to recover following N-TIRE ablation and the effects of treatment were monitored with clinical and magnetic resonance imaging examinations. Brains were subjected to histopathologic and ultrastructural assessment along with Bcl-2, caspase-3, and caspase-9 immunohistochemical staining following sacrifice 72 h post-treatment. Adverse clinical effects of N-TIRE were only observed in the dog treated at the upper energy tier. MRI and neuropathologic examinations indicated that N-TIRE ablation resulted in focal regions of severe cytoarchitectural and blood-brain-barrier disruption. Lesion size correlated to the intensity of the applied electrical field. N-TIRE-induced lesions were characterized by parenchymal necrosis and hemorrhage; however, large blood vessels were preserved. A transition zone containing parenchymal edema, perivascular inflammatory cuffs, and reactive gliosis was interspersed between the necrotic focus and normal neuropil. Apoptotic labeling indices were not different between the N-TIRE-treated and control brains. This study identified N-TIRE pulse parameters that can be used to safely create circumscribed foci of brain necrosis while selectively preserving major vascular structures. PMID:23820168

  15. Pathology of non-thermal irreversible electroporation (N-TIRE)-induced ablation of the canine brain

    PubMed Central

    Garcia, Paulo A.; Roberston, John L.; Ellis, Thomas L.; Davalos, Rafael V.

    2013-01-01

    This study describes the neuropathologic features of normal canine brain ablated with non-thermal irreversible electroporation (N-TIRE). The parietal cerebral cortices of four dogs were treated with N-TIRE using a dose-escalation protocol with an additional dog receiving sham treatment. Animals were allowed to recover following N-TIRE ablation and the effects of treatment were monitored with clinical and magnetic resonance imaging examinations. Brains were subjected to histopathologic and ultrastructural assessment along with Bcl-2, caspase-3, and caspase-9 immunohistochemical staining following sacrifice 72 h post-treatment. Adverse clinical effects of N-TIRE were only observed in the dog treated at the upper energy tier. MRI and neuropathologic examinations indicated that N-TIRE ablation resulted in focal regions of severe cytoarchitectural and blood-brain-barrier disruption. Lesion size correlated to the intensity of the applied electrical field. N-TIRE-induced lesions were characterized by parenchymal necrosis and hemorrhage; however, large blood vessels were preserved. A transition zone containing parenchymal edema, perivascular inflammatory cuffs, and reactive gliosis was interspersed between the necrotic focus and normal neuropil. Apoptotic labeling indices were not different between the N-TIRE-treated and control brains. This study identified N-TIRE pulse parameters that can be used to safely create circumscribed foci of brain necrosis while selectively preserving major vascular structures. PMID:23820168

  16. The Effects of Irreversible Electroporation on the Achilles Tendon: An Experimental Study in a Rabbit Model

    PubMed Central

    Yan, Mingwei; Ding, Weidong; Xu, Kui; Fan, Qingyu; Li, Zhao

    2015-01-01

    Background To evaluate the potential effects of irreversible electroporation ablation on the Achilles tendon in a rabbit model and to compare the histopathological and biomechanical changes between specimens following electroporation ablation and radiofrequency ablation. Methods A total of 140 six-month-old male New Zealand rabbits were used. The animals were randomly divided into two groups, 70 in the radiofrequency ablation group and 70 in the electroporation group. In situ ablations were applied directly to the Achilles tendons of rabbits using typical electroporation (1800 V/cm, 90 pulses) and radiofrequency ablation (power control mode) protocols. Histopathological and biomechanical evaluations were performed to examine the effects of electroporation ablation and radiofrequency ablation over time. Results Both electroporation and radiofrequency ablation produced complete cell ablation in the target region. Thermal damage resulted in tendon rupture 3 days post radiofrequency ablation. In contrast, electroporation-ablated Achilles tendons preserved their biomechanical properties and showed no detectable rupture at this time point. The electroporation-ablated tendons exhibited signs of recovery, including tenoblast regeneration and angiogenesis within 2 weeks, and the restoration of their integral structure was evident within 12 weeks. Conclusions When applying electroporation to ablate solid tumors, major advantage could be that collateral damage to adjacent tendons or ligaments is minimized due to the unique ability of electroporation ablation to target the cell membrane. This advantage could have a significant impact on the field of tumor ablation near vital tendons or ligaments. PMID:26114962

  17. Protein Footprinting by the Combined Use of Reversible and Irreversible Lysine Modifications

    NASA Astrophysics Data System (ADS)

    Hanai, Ryo; Wang, James C.

    1994-12-01

    A two-step lysine-modification procedure has been devised to chemically footprint protein surfaces involved in macromolecular interactions. A protein tagged at one particular end, in the free state or in a complex, is first treated lightly with a reversible lysine-modifying reagent. The protein is then unfolded and treated extensively with an irreversible lysine reagent to block those lysines that did not react previously; next, the first lysine modification is reversed, and a lysine-specific endoproteinase is used to cleave the tagged polypeptide at the deblocked lysines. Separation of the proteolytic products by size and identification of the tagged fragments map the positions of these lysines. In this procedure, the reversible lysine reagent serves as the chemical footprinting agent, as cleavage of the polypeptide ensues only at the sites of reaction with this reagent. Lysines involved in macromolecular contacts are identified from differences in proteolytic patterns of the tagged protein when the first lysine modification is done with the protein in the free form and in a complex. Application of the method to vaccinia virus topoisomerase identifies a number of lysines that are involved in its binding to DNA.

  18. Post-hatch heat warms adult beaks: irreversible physiological plasticity in Japanese quail.

    PubMed

    Burness, Gary; Huard, Jacqueline R; Malcolm, Emily; Tattersall, Glenn J

    2013-09-22

    Across taxa, the early rearing environment contributes to adult morphological and physiological variation. For example, in birds, environmental temperature plays a key role in shaping bill size and clinal trends across latitudinal/thermal gradients. Such patterns support the role of the bill as a thermal window and in thermal balance. It remains unknown whether bill size and thermal function are reversibly plastic. We raised Japanese quail in warm (30°C) or cold (15°C) environments and then at a common intermediate temperature. We predicted that birds raised in cold temperatures would develop smaller bills than warm-reared individuals, and that regulation of blood flow to the bill in response to changing temperatures would parallel the bill's role in thermal balance. Cold-reared birds developed shorter bills, although bill size exhibited 'catch-up' growth once adults were placed at a common temperature. Despite having lived in a common thermal environment as adults, individuals that were initially reared in the warmth had higher bill surface temperatures than cold-reared individuals, particularly under cold conditions. This suggests that blood vessel density and/or the control over blood flow in the bill retained a memory of early thermal ontogeny. We conclude that post-hatch temperature reversibly affects adult bill morphology but irreversibly influences the thermal physiological role of bills and may play an underappreciated role in avian energetics.

  19. Irreversible Wash Aid Additive for Cesium Mitigation. Small-Scale Demonstration and Lessons Learned

    SciTech Connect

    Kaminski, Michael

    2015-01-01

    The Irreversible Wash Aid Additive process has been under development by the U.S. Environmental Protection Agency (EPA) and Argonne National Laboratory (Argonne). This process for radioactive cesium mitigation consists of a solution to wash down contaminated structures, roadways, and vehicles and a sequestering agent to bind the radionuclides from the wash water and render them environmentally immobile. The purpose of this process is to restore functionality to basic services and immediately reduce the consequences of a radiologically-contaminated urban environment. Research and development have resulted in a down-selection of technologies for integration and demonstration at the pilot-scale level as part of the Wide Area Recovery and Resiliency Program (WARRP) under the Department of Homeland Security and the Denver Urban Area Security Initiative. As part of developing the methods for performing a pilot-scale demonstration at the WARRP conference in Denver in 2012, Argonne conducted small-scale field experiments at Separmatic Systems. The main purpose of these experiments was to refine the wash water collection and separations systems and demonstrate key unit operations to help in planning for the large scale demonstration in Denver. Since the purpose of these tests was to demonstrate the operations of the system, we used no radioactive materials. After a brief set of experiments with the LAKOS unit to familiarize ourselves with its operation, two experiments were completed on two separate dates with the Separmatic systems.

  20. Irreversible electroporation and the pancreas: What we know and where we are going?

    PubMed

    Young, Shamar J

    2015-08-27

    Pancreatic adenocarcinoma continues to have a poor prognosis with 1 and 5 years survival rates of 27% and 6% respectively. The gold standard of treatment is resection, however, only approximately 10% of patients present with resectable disease. Approximately 40% of patients present with disease that is too locally advanced to resect. There is great interest in improving outcomes in this patient population and ablation techniques have been investigated as a potential solution. Unfortunately early investigations into thermal ablation techniques, particularly radiofrequency ablation, resulted in unacceptably high morbidity rates. Irreversible electroporation (IRE) has been introduced and is promising as it does not rely on thermal energy and has shown an ability to leave structural cells such as blood vessels and bile ducts intact during animal studies. IRE also does not suffer from heat sink effect, a concern given the large number of blood vessels surrounding the pancreas. IRE showed significant promise during preclinical animal trials and as such has moved on to clinical testing. There are as of yet only a few studies which look at the applications of IRE within humans in the setting of pancreatic adenocarcinoma. This paper reviews the basic principles, techniques, and current clinical data available on IRE.

  1. Exchangeable Colloidal AFM Probes for the Quantification of Irreversible and Long-Term Interactions

    PubMed Central

    Dörig, Pablo; Ossola, Dario; Truong, Anh Minh; Graf, Monika; Stauffer, Flurin; Vörös, János; Zambelli, Tomaso

    2013-01-01

    An original method is presented to study single-colloid interaction with a substrate in liquid environment. Colloids, either in solution or adsorbed on a surface, are fixed by suction against the aperture of a microchanneled atomic force microscopy cantilever. Their adhesion to the substrate is measured, followed by their release via a short overpressure surge. Such colloid exchange procedure allows for 1), the quick variation of differently functionalized colloids within the same experiment; 2), the investigation of long-term interactions by leaving the colloids on a surface for a defined time before detaching them; and 3), the inspection of irreversible interactions. After validation of the method by reproducing literature results obtained with traditional colloidal atomic force microscopy, the serial use of colloids with different surface functionalization was shown on a micropatterned surface. Finally, concanavalin A-coated colloids were allowed to adsorb on human embryonic kidney cells and then detached one by one. The adhesion between cells and colloids was up to 60 nN, whereas individual cells adhered with 20 nN to the glass substrate. A cellular elastic modulus of 0.8 kPa was determined using the attached colloid as indenter. PMID:23870267

  2. Transcriptome signature of irreversible senescence in human papillomavirus-positive cervical cancer cells

    PubMed Central

    Wells, Susanne I.; Aronow, Bruce J.; Wise, Trisha M.; Williams, Sarah S.; Couget, Jennifer A.; Howley, Peter M.

    2003-01-01

    A frequent characteristic of human papillomavirus (HPV)-positive cervical cancers is the loss of viral E2 gene expression in HPV-infected cervical epithelial cells as a consequence of viral DNA integration into the cellular genome. The expression of E2 in HPV-positive cancer cells results in the repression of the viral E6/E7 oncogenes, activation of the p53 and pRB pathways, and a G1 cell cycle arrest, followed by induction of cellular senescence. The transcriptional consequences of E2-mediated cell cycle arrest that lead to senescence currently are unknown. Using conditional senescence induction in HeLa cells and microarray analysis, we describe here the expression profile of cells irreversibly committed to senescence. Our results provide insight into the molecular anatomy of senescence pathways and its regulation by HPV on-coproteins. These include the induction of the RAB vesicular transport machinery and a general down-regulation of chromatin regulatory molecules. The repression of tumor-specific G antigens during E2 senescence supports a reversal of the tumorigenic phenotype by E2 and the potential approach of tumor-specific G antigen-specific immunotherapy for cervical cancer. PMID:12756294

  3. Bacterial, fungal and yeast contamination in six brands of irreversible hydrocolloid impression materials.

    PubMed

    Casemiro, Luciana Assirati; Martins, Carlos Henrique Gomes; de Souza, Fernanda de Carvalho Panzeri Pires; Panzeri, Heitor; Ito, Isabel Yoko

    2007-01-01

    This study assessed the level of contamination of six commercially available irreversible hydrocolloids (two containing chlorhexidine) and identified the contamination present in the materials. Petri dishes containing selective and enriched culture media were inoculated with alginate powder (0.06 g), in triplicate. After incubation (37 degrees C/7 days), the colony-forming units (CFU) were counted and Gram stained. Biochemical identification of the different morphotypes was also performed. The contamination levels for the materials were: Jeltrate--389 CFU/g; Jeltrate Plus--516 CFU/g; Jeltrate Chromatic--135 CFU/g; Hydrogum--1,455 CFU/g; Kromopan--840 CFU/g; and Greengel--59 CFU/g. Gram staining revealed the presence of Gram-positive bacillus and Gram-positive cocci. The bacteria Staphylococcus epidermidis, Bacillus subtilis, Bacillus sp., Bacillus coagulans, Bacillus licheniformis, Bacillus cereus, Micrococcus luteus, and Nocardia sp.; the filamentous fungi Aspergillus niger, Aspergillus flavus, Rhizopus sp., Neurospora sp.; and the yeast Candida sp. were isolated. The contamination detected in the impression materials points out the need for adopting measures to improve the microbiological quality of these materials. The use of contaminated materials in the oral cavity goes against the basic principles for controlling cross-contamination and may represent a risk for debilitated or immunocompromised patients. PMID:17589644

  4. Susceptibility of the early Earth to irreversible glaciation caused by carbon dioxide clouds.

    PubMed

    Caldeira, K; Kasting, J F

    1992-09-17

    Simple energy-balance climate models of the Budyko/Sellers type predict that a small (2-5%) decrease in solar output could result in runaway glaciation on the Earth. But solar fluxes 25-30% lower early in the Earth's history apparently did not lead to this result. One currently favoured explanation is that high partial pressures of carbon dioxide, caused by higher volcanic outgassing rates and/or slower rates of silicate weathering, created a large enough greenhouse effect to keep the planet warm. This does not resolve the problem of climate stability, however, because as we argue here, the oceans can freeze much more quickly than CO2 can accumulate in the atmosphere. Had such a transient global glaciation occurred in the distant past when solar luminosity was low, it might have been irreversible because of the formation of highly reflective CO2 clouds, similar to those encountered in climate simulations of early Mars. Our simulations of the early Earth, incorporating the possible formation of such clouds, suggest that the Earth might not be habitable today had it not been warm during the first part of its history.

  5. Local equilibrium and the second law of thermodynamics for irreversible systems with thermodynamic inertia.

    PubMed

    Glavatskiy, K S

    2015-10-28

    Validity of local equilibrium has been questioned for non-equilibrium systems which are characterized by delayed response. In particular, for systems with non-zero thermodynamic inertia, the assumption of local equilibrium leads to negative values of the entropy production, which is in contradiction with the second law of thermodynamics. In this paper, we address this question by suggesting a variational formulation of irreversible evolution of a system with non-zero thermodynamic inertia. We introduce the Lagrangian, which depends on the properties of the normal and the so-called "mirror-image" systems. We show that the standard evolution equations, in particular, the Maxwell-Cattaneo-Vernotte equation, can be derived from the variational procedure without going beyond the assumption of local equilibrium. We also argue that the second law of thermodynamics in non-equilibrium should be understood as a consequence of the variational procedure and the property of local equilibrium. For systems with instantaneous response this leads to the standard requirement of the local instantaneous entropy production being always positive. However, if a system is characterized by delayed response, the formulation of the second law of thermodynamics should be altered. In particular, the quantity, which is always positive, is not the instantaneous entropy production, but the entropy production averaged over a proper time interval. PMID:26520492

  6. New fully superconducting bearing concept using the difference in irreversibility field of two superconducting components

    NASA Astrophysics Data System (ADS)

    Patel, A.; Palka, R.; Glowacki, B. A.

    2011-01-01

    One of the major factors limiting levitation force for existing superconducting magnetic bearings is the maximum possible remanence of 1.4 T known to exist for rare-earth permanent magnets. This paper introduces the novel concept of a magnetic bearing which uses the difference in irreversibility field of two superconducting components to allow one component to be field cooled in the field originating from the other component which is first magnetized at a higher temperature. Magnetized (RE)BCO bulks with high trapped fields can be used as one of the components instead of permanent magnets, giving a significant increase in the levitation force density that can be achieved between the two components. This paper focuses on using an MgB2 hollow cylinder for the component which is field cooled. Modelling of the levitation forces that would exist between magnetized YBCO bulks inside a hollow MgB2 cylinder is reported as well as modelling of pulsed field magnetization of the pellets to create high field gradients using MPSC (multi-pulse technique with step-wise cooling). The new design has the potential to achieve levitation force densities over 100 N cm - 2.

  7. Magnetic irreversibility and pinning force density in the Mo100-xRex alloy superconductors

    NASA Astrophysics Data System (ADS)

    Sundar, Shyam; Chattopadhyay, M. K.; Sharath Chandra, L. S.; Roy, S. B.

    2015-12-01

    We have measured the isothermal field dependence of magnetization of the Mo100-xRex (15 ⩽ x ⩽ 48) alloys, and have estimated the critical current and pinning force density from these measurements. We have performed structural characterization of the above alloys using standard techniques, and analyzed the field dependence of critical current and pinning force density using existing theories. Our results indicate that dislocation networks and point defects like voids and interstitial imperfections are the main flux line pinning centers in the Mo100-xRex alloys in the intermediate fields, i.e., in the "small bundle" flux line pinning regime. In this regime, the critical current density is also quite robust against increasing magnetic field. In still higher fields, the critical current density is affected by flux creep. In the low field regime, on the other hand, the pinning of the flux lines seems to be influenced by the presence of two superconducting energy gaps in the Mo100-xRex alloys. This modifies the field dependence of critical current density, and also seems to contribute to the asymmetry in the magnetic irreversibility exhibited by the isothermal field dependence of magnetization.

  8. Irreversible bonding of polyimide and polydimethylsiloxane (PDMS) based on a thiol-epoxy click reaction

    NASA Astrophysics Data System (ADS)

    Hoang, Michelle V.; Chung, Hyun-Joong; Elias, Anastasia L.

    2016-10-01

    Polyimide is one of the most popular substrate materials for the microfabrication of flexible electronics, while polydimethylsiloxane (PDMS) is the most widely used stretchable substrate/encapsulant material. These two polymers are essential in fabricating devices for microfluidics, bioelectronics, and the internet of things; bonding these materials together is a crucial challenge. In this work, we employ click chemistry at room temperature to irreversibly bond polyimide and PDMS through thiol-epoxy bonds using two different methods. In the first method, we functionalize the surfaces of the PDMS and polyimide substrates with mercaptosilanes and epoxysilanes, respectively, for the formation of a thiol-epoxy bond in the click reaction. In the second method, we functionalize one or both surfaces with mercaptosilane and introduce an epoxy adhesive layer between the two surfaces. When the surfaces are bonded using the epoxy adhesive without any surface functionalization, an extremely small peel strength (<0.01 N mm-1) is measured with a peel test, and adhesive failure occurs at the PDMS surface. With surface functionalization, however, remarkably higher peel strengths of ~0.2 N mm-1 (method 1) and  >0.3 N mm-1 (method 2) are observed, and failure occurs by tearing of the PDMS layer. We envision that the novel processing route employing click chemistry can be utilized in various cases of stretchable and flexible device fabrication.

  9. In vivo non-thermal irreversible electroporation impact on rat liver galvanic apparent internal resistance

    NASA Astrophysics Data System (ADS)

    Golberg, A.; Laufer, S.; Rabinowitch, H. D.; Rubinsky, B.

    2011-02-01

    Non-thermal irreversible electroporation (NTIRE) is a biophysical phenomenon which involves application of electric field pulses to cells or tissues, causing certain rearrangements in the membrane structure leading to cell death. The treated tissue ac impedance changes induced by electroporation were shown to be the indicators for NTIRE efficiency. In a previous study we characterized in vitro tissue galvanic apparent internal resistance (GAIR) changes due to NTIRE. Here we describe an in vivo study in which we monitored the GAIR changes of a rat liver treated by NTIRE. Electrical pulses were delivered through the same Zn/Cu electrodes by which GAIR was measured. GAIR was measured before and for 3 h after the treatment at 15 min intervals. The results were compared to the established ac bioimpedance measurement method. A decrease of 33% was measured immediately after the NTIRE treatment and a 40% decrease was measured after 3 h in GAIR values; in the same time 40% and 47% decrease respectively were measured by ac bioimpedance analyses. The temperature increase due to the NTIRE was only 0.5 °C. The results open the way for an inexpensive, self-powered in vivo real-time NTIRE effectiveness measurement.

  10. Bacterial, fungal and yeast contamination in six brands of irreversible hydrocolloid impression materials.

    PubMed

    Casemiro, Luciana Assirati; Martins, Carlos Henrique Gomes; de Souza, Fernanda de Carvalho Panzeri Pires; Panzeri, Heitor; Ito, Isabel Yoko

    2007-01-01

    This study assessed the level of contamination of six commercially available irreversible hydrocolloids (two containing chlorhexidine) and identified the contamination present in the materials. Petri dishes containing selective and enriched culture media were inoculated with alginate powder (0.06 g), in triplicate. After incubation (37 degrees C/7 days), the colony-forming units (CFU) were counted and Gram stained. Biochemical identification of the different morphotypes was also performed. The contamination levels for the materials were: Jeltrate--389 CFU/g; Jeltrate Plus--516 CFU/g; Jeltrate Chromatic--135 CFU/g; Hydrogum--1,455 CFU/g; Kromopan--840 CFU/g; and Greengel--59 CFU/g. Gram staining revealed the presence of Gram-positive bacillus and Gram-positive cocci. The bacteria Staphylococcus epidermidis, Bacillus subtilis, Bacillus sp., Bacillus coagulans, Bacillus licheniformis, Bacillus cereus, Micrococcus luteus, and Nocardia sp.; the filamentous fungi Aspergillus niger, Aspergillus flavus, Rhizopus sp., Neurospora sp.; and the yeast Candida sp. were isolated. The contamination detected in the impression materials points out the need for adopting measures to improve the microbiological quality of these materials. The use of contaminated materials in the oral cavity goes against the basic principles for controlling cross-contamination and may represent a risk for debilitated or immunocompromised patients.

  11. Traffic time series analysis by using multiscale time irreversibility and entropy

    NASA Astrophysics Data System (ADS)

    Wang, Xuejiao; Shang, Pengjian; Fang, Jintang

    2014-09-01

    Traffic systems, especially urban traffic systems, are regulated by different kinds of interacting mechanisms which operate across multiple spatial and temporal scales. Traditional approaches fail to account for the multiple time scales inherent in time series, such as empirical probability distribution function and detrended fluctuation analysis, which have lead to different results. The role of multiscale analytical method in traffic time series is a frontier area of investigation. In this paper, our main purpose is to introduce a new method—multiscale time irreversibility, which is helpful to extract information from traffic time series we studied. In addition, to analyse the complexity of traffic volume time series of Beijing Ring 2, 3, 4 roads between workdays and weekends, which are from August 18, 2012 to October 26, 2012, we also compare the results by this new method and multiscale entropy method we have known well. The results show that the higher asymmetry index we get, the higher traffic congestion level will be, and accord with those which are obtained by multiscale entropy.

  12. Irreversible electroporation: Medical application of intense electric pulses for sustainable health

    NASA Astrophysics Data System (ADS)

    Kurata, Kosaku; Takamatsu, Hiroshi

    2016-03-01

    Irreversible electroporation (IRE) is a promising method for the ablation of tumors using intense electric pulses. Because the mechanism of IRE is based on the breaking of the cytoplasmic membrane, only the cells are necrotized non-thermally without causing damage to the extracellular matrix when pulse settings are optimized to avoid Joule heating. In IRE therapy, a train of electric pulses of a few kilovolts is applied to the targeted tissue via a pair of electrodes. To definitely ablate the tissue and minimize the temperature rise during the application of pulses, determination of the adequate settings of the pulsesand electrode configuration prior to the therapy are important. Studies from the engineering perspective are therefore highly helpful for the successful use of IRE. In the current study, the authors' work associated with IRE will be introduced, including a 3D numerical simulation for the estimation of the electric field and temperature distribution around the electrodes, IRE experiment with a 3D cell culture model, and evaluation of cell destruction and thermal injury.

  13. Mesenchymal stem cells with irreversibly arrested proliferation stimulate decidua development in rats

    PubMed Central

    Domnina, Alisa P.; Novikova, Polina V.; Lyublinskaya, Olga G.; Zenin, Valeriy V.; Fridlyanskaya, Irina I.; Mikhailov, Vyacheslav M.; Nikolsky, Nikolay N.

    2016-01-01

    Stem cell transplantation, which is based on the application of mesenchymal stem/stromal cells (MSCs), is a rapidly developing approach to the regenerative therapy of various degenerative disorders characterized by brain and heart failure, as well as skin lesions. In comparison, the use of stem cell transplantations to treat infertility has received less attention. One of the causes of miscarriages and fetal growth delay is the loss of the decidual reaction of endometrial cells. The present study modeled decidualization processes in pseudopregnant rats. For cell transplantation experiments, the rats were transplanted with MSCs established from endometrial fragments in menstrual blood (eMSCs). These cells express common MSC markers, are multipotent and are able to differentiate into various tissue lineages. Cell therapy frequently requires substantial cell biomass, and cultivation of MSCs may be accompanied by significant changes to their properties, including malignant transformation. In order to minimize the potential for malignant transformation, the proliferation of eMSCs was irreversibly suppressed by irradiation and mitomycin C treatment. Transplantation of the rats with viable, non-proliferating eMSCs stimulated the development of all elements of decidual tissue. Conversely, transplantation of the rats with cells killed using 95% ethanol did not result in the development of decidual tissue. The present study demonstrated the potential for applying eMSCs to the cellular therapy of infertility associated with endometrial disorders characterized by decidualization insufficiency and implantation failure. In addition, the transplantation of viable but non-proliferating cells ensured that their oncogenic potential was limited.

  14. Percutaneous Irreversible Electroporation Lung Ablation: Preliminary Results in a Porcine Model

    SciTech Connect

    Deodhar, Ajita; Monette, Sebastien; Single, Gordon W.; Hamilton, William C.; Thornton, Raymond H.; Sofocleous, Constantinos T.; Maybody, Majid; Solomon, Stephen B.

    2011-12-15

    Objective: Irreversible electroporation (IRE) uses direct electrical pulses to create permanent 'pores' in cell membranes to cause cell death. In contrast to conventional modalities, IRE has a nonthermal mechanism of action. Our objective was to study the histopathological and imaging features of IRE in normal swine lung. Materials and Methods: Eleven female swine were studied for hyperacute (8 h), acute (24 h), subacute (96 h), and chronic (3 week) effects of IRE ablation in lung. Paired unipolar IRE applicators were placed under computed tomography (CT) guidance. Some applicators were deliberately positioned near bronchovascular structures. IRE pulse delivery was synchronized with the cardiac rhythm only when ablation was performed within 2 cm of the heart. Contrast-enhanced CT scan was performed immediately before and after IRE and at 1 and 3 weeks after IRE ablation. Representative tissue was stained with hematoxylin and eosin for histopathology. Results: Twenty-five ablations were created: ten hyperacute, four acute, and three subacute ablations showed alveolar edema and necrosis with necrosis of bronchial, bronchiolar, and vascular epithelium. Bronchovascular architecture was maintained. Chronic ablations showed bronchiolitis obliterans and alveolar interstitial fibrosis. Immediate post-procedure CT images showed linear or patchy density along the applicator tract. At 1 week, there was consolidation that resolved partially or completely by 3 weeks. Pneumothorax requiring chest tube developed in two animals; no significant cardiac arrhythmias were noted. Conclusion: Our preliminary porcine study demonstrates the nonthermal and extracellular matrix sparing mechanism of action of IRE. IRE is a potential alternative to thermal ablative modalities.

  15. A non-linear irreversible thermodynamic perspective on organic pigment proliferation and biological evolution

    NASA Astrophysics Data System (ADS)

    Michaelian, K.

    2013-12-01

    The most important thermodynamic work performed by life today is the dissipation of the solar photon flux into heat through organic pigments in water. From this thermodynamic perspective, biological evolution is thus just the dispersal of organic pigments and water throughout Earth's surface, while adjusting the gases of Earth's atmosphere to allow the most intense part of the solar spectrum to penetrate the atmosphere and reach the surface to be intercepted by these pigments. The covalent bonding of atoms in organic pigments provides excited levels compatible with the energies of these photons. Internal conversion through vibrational relaxation to the ground state of these excited molecules when in water leads to rapid dissipation of the solar photons into heat, and this is the major source of entropy production on Earth. A non-linear irreversible thermodynamic analysis shows that the proliferation of organic pigments on Earth is a direct consequence of the pigments catalytic properties in dissipating the solar photon flux. A small part of the energy of the photon goes into the production of more organic pigments and supporting biomass, while most of the energy is dissipated and channeled into the hydrological cycle through the latent heat of vaporization of surface water. By dissipating the surface to atmosphere temperature gradient, the hydrological cycle further increases the entropy production of Earth. This thermodynamic perspective of solar photon dissipation by life has implications to the possibility of finding extra-terrestrial life in our solar system and the Universe.

  16. Local Control of Perivascular Malignant Liver Lesions Using Percutaneous Irreversible Electroporation: Initial Experiences

    SciTech Connect

    Eller, Achim Schmid, Axel; Schmidt, Joachim; May, Matthias Brand, Michael Saake, Marc Uder, Michael Lell, Michael

    2015-02-15

    PurposeThis study was designed to assess efficacy and safety in the treatment of perivascular malignant liver lesions using percutaneous, computed tomography (CT)-guided irreversible electroporation (IRE).MethodsFourteen patients (mean age 58 ± 11 years) with 18 malignant liver lesions were consecutively enrolled in this study. IRE was performed in patients not eligible for surgery and lesions abutting large vessels or bile ducts. Follow-up exams were performed using multislice-CT (MS-CT) or MRI.ResultsMedium lesion diameter was 20 ± 5 mm. Ten of 14 (71 %) were successfully treated with no local recurrence to date (mean follow-up 388 ± 160 days). One case left initial tumor control unclear and additional RFA was performed 4 weeks after IRE. Complications occurred in 4 of 14 (29 %) cases. In one case, intervention was terminated and abdominal bleeding required laparotomy. In two cases, a postinterventional hematothorax required intervention. In another case, abdominal bleeding could be managed conservatively. No complications related to the bile ducts occurred.ConclusionsPercutaneous IRE seems to be effective in perivascular lesions but is associated with a higher complication rate compared with thermoablative techniques.

  17. Exchangeable colloidal AFM probes for the quantification of irreversible and long-term interactions.

    PubMed

    Dörig, Pablo; Ossola, Dario; Truong, Anh Minh; Graf, Monika; Stauffer, Flurin; Vörös, János; Zambelli, Tomaso

    2013-07-16

    An original method is presented to study single-colloid interaction with a substrate in liquid environment. Colloids, either in solution or adsorbed on a surface, are fixed by suction against the aperture of a microchanneled atomic force microscopy cantilever. Their adhesion to the substrate is measured, followed by their release via a short overpressure surge. Such colloid exchange procedure allows for 1), the quick variation of differently functionalized colloids within the same experiment; 2), the investigation of long-term interactions by leaving the colloids on a surface for a defined time before detaching them; and 3), the inspection of irreversible interactions. After validation of the method by reproducing literature results obtained with traditional colloidal atomic force microscopy, the serial use of colloids with different surface functionalization was shown on a micropatterned surface. Finally, concanavalin A-coated colloids were allowed to adsorb on human embryonic kidney cells and then detached one by one. The adhesion between cells and colloids was up to 60 nN, whereas individual cells adhered with 20 nN to the glass substrate. A cellular elastic modulus of 0.8 kPa was determined using the attached colloid as indenter.

  18. The myeloperoxidase product hypochlorous acid generates irreversible high-density lipoprotein receptor inhibitors

    PubMed Central

    Binder, Veronika; Ljubojevic, Senka; Haybaeck, Johannes; Holzer, Michael; El-Gamal, Dalia; Schicho, Rudolf; Pieske, Burkert; Heinemann, Akos; Marsche, Gunther

    2014-01-01

    Objective Elevated levels of advanced oxidation protein products (AOPPs) have been described in several chronic inflammatory diseases, like chronic renal insufficiency, rheumatoid arthritis and atherosclerosis. Recent findings revealed that AOPPs are inhibitors of the major high-density lipoprotein (HDL) receptor, scavenger receptor class B, type 1 (SR-BI). Here we investigated what oxidation induced structural alterations convert plasma albumin into an HDL-receptor inhibitor. Approach and Results Exposure of albumin to the physiological oxidant, hypochlorous acid, generated high affinity SR-BI ligands. Protection of albumin lysine-residues prior exposure to hypochlorous acid as well as regeneration of N-chloramines after oxidation of albumin completely prevented binding of oxidized albumin to SR-BI, indicating that modification of albumin lysine-residues is required to generate SR-BI ligands. Of particular interest, N-chloramines within oxidized albumin promoted irreversible binding to SR-BI, resulting in permanent receptor blockade. We observed that the SR-BI inhibitory activity of albumin isolated from chronic kidney disease patients correlated with the content of the myeloperoxidase-specific oxidation product 3-chlorotyrosine and was associated with alterations in the composition of HDL. Conclusion Given that several potential atheroprotective activities of HDL are mediated by SR-BI, the present results raise the possibility that oxidized plasma albumin, through permanent SR-BI blockade, contributes to the pathophysiology of cardiovascular disease. PMID:23493288

  19. Long-term experiments to investigate irreversibility in sorption of pesticides to soil.

    PubMed

    Suddaby, L A; Beulke, S; van Beinum, W; Oliver, R G; Kuet, S; Brown, C D

    2016-11-01

    Experiments investigated irreversibility in pesticide sorption to soil. Sorption behaviour under abiotic conditions was quantified for chlorotoluron, prometryn and hexaconazole in three soils over periods of up to 274 days. An isotope-exchange procedure was used whereby sorption of (12)C- and (14)C-pesticide isotopes in shaken suspensions of three soils (56-168 days shaking) was followed by substitution of the isotopes in the liquid phase and a 14-day exchange phase. This was followed by forced isotope exchange where the sorbed (14)C material was exchanged by adding an excess of non-radiolabelled compound. Experiments were concluded with solvent extraction and soil combustion to determine remaining radioactivity. Under conditions of continuous shaking, the pesticide-soil systems took around four months to approach sorption equilibrium, resulting in strong asymmetry between the profiles of exchange for isotopes of all three compounds. Physically entrapped residues were released back into solution under the steep concentration gradient of forced isotope exchange and small amounts of radioactivity were still being released at the termination of the experiment. The profiles of exchange did not deviate markedly from ideal behaviour based on the assumption that sorption is fully reversible. Whilst the timescales for release of sorbed residues back into solution were very long, soil combustion at study termination only yielded <1-2% of applied radioactivity; this confirms that sorption processes under abiotic soil conditions were overwhelmingly reversible for this set of compounds and soils. PMID:27479454

  20. Histological and finite element analysis of cell death due to irreversible electroporation.

    PubMed

    Long, G; Bakos, G; Shires, P K; Gritter, L; Crissman, J W; Harris, J L; Clymer, J W

    2014-12-01

    Irreversible electroporation (IRE) has been shown to be an effective method of killing cells locally. In contrast to radiofrequency ablation, the mechanism by which cells are thought to die via IRE is the creation of pores in cell membranes, without substantial increase in tissue temperature. To determine the degree to which cell death is non-thermal, we evaluated IRE in porcine hepatocytes in vivo. Using pulse widths of 10 µs, bursts of 3 kV square-wave pulses were applied through a custom probe to the liver of an anesthetized pig. Affected tissue was evaluated histologically via stainings of hematoxylin & eosin (H&E), nitroblue tetrazolium (NBT) to monitor cell respiration and TUNEL to gauge apoptosis. Temperature was measured during the application of electroporation, and heat transfer was modeled via finite element analysis. Cell death was calculated via Arrhenius kinetics. Four distinct zones were observed within the ring return electrode; heat-fixed tissue, coagulation, necrotic, and viable. The Arrhenius damage integral estimated complete cell death only in the first zone, where the temperature exceeded 70°C, and partial or no cell death in the other zones, where maximum temperature was approximately 45°C. Except for a limited area near the electrode tip, cell death in IRE is predominantly due to a non-thermal mechanism.

  1. The central role of ketones in reversible and irreversible hydrothermal organic functional group transformations

    NASA Astrophysics Data System (ADS)

    Yang, Ziming; Gould, Ian R.; Williams, Lynda B.; Hartnett, Hilairy E.; Shock, Everett L.

    2012-12-01

    Studies of hydrothermal reactions involving organic compounds suggest complex, possibly reversible, reaction pathways that link functional groups from reduced alkanes all the way to oxidized carboxylic acids. Ketones represent a critical functional group because they occupy a central position in the reaction pathway, at the point where Csbnd C bond cleavage is required for the formation of the more oxidized carboxylic acids. The mechanisms for the critical bond cleavage reactions in ketones, and how they compete with other reactions are the focus of this experimental study. We studied a model ketone, dibenzylketone (DBK), in H2O at 300 °C and 70 MPa for up to 528 h. Product analysis was performed as a function of time at low DBK conversions to reveal the primary reaction pathways. Reversible interconversion between ketone, alcohol, alkene and alkane functional groups is observed in addition to formation of radical coupling products derived from irreversible Csbnd C and Csbnd H homolytic bond cleavage. The product distributions are time-dependent but the bond cleavage products dominate. The major products that accumulate at longer reaction times are toluene and larger, dehydrogenated structures that are initially formed by radical coupling. The hydrogen atoms generated by dehydrogenation of the coupling products are predominantly consumed in the formation of toluene. Even though bond cleavage products dominate, no carboxylic acids were observed on the timescale of the reactions under the chosen experimental conditions.

  2. The role of beaded activated carbon's surface oxygen groups on irreversible adsorption of organic vapors.

    PubMed

    Jahandar Lashaki, Masoud; Atkinson, John D; Hashisho, Zaher; Phillips, John H; Anderson, James E; Nichols, Mark

    2016-11-01

    The objective of this study is to determine the contribution of surface oxygen groups to irreversible adsorption (aka heel formation) during cyclic adsorption/regeneration of organic vapors commonly found in industrial systems, including vehicle-painting operations. For this purpose, three chemically modified activated carbon samples, including two oxygen-deficient (hydrogen-treated and heat-treated) and one oxygen-rich sample (nitric acid-treated) were prepared. The samples were tested for 5 adsorption/regeneration cycles using a mixture of nine organic compounds. For the different samples, mass balance cumulative heel was 14 and 20% higher for oxygen functionalized and hydrogen-treated samples, respectively, relative to heat-treated sample. Thermal analysis results showed heel formation due to physisorption for the oxygen-deficient samples, and weakened physisorption combined with chemisorption for the oxygen-rich sample. Chemisorption was attributed to consumption of surface oxygen groups by adsorbed species, resulting in formation of high boiling point oxidation byproducts or bonding between the adsorbates and the surface groups. Pore size distributions indicated that different pore sizes contributed to heel formation - narrow micropores (<7Å) in the oxygen-deficient samples and midsize micropores (7-12Å) in the oxygen-rich sample. The results from this study help explain the heel formation mechanism and how it relates to chemically tailored adsorbent materials. PMID:27295065

  3. Reversible versus irreversible binding of transferrin to polystyrene nanoparticles: soft and hard corona.

    PubMed

    Milani, Silvia; Bombelli, Francesca Baldelli; Pitek, Andrzej S; Dawson, Kenneth A; Rädler, Joachim

    2012-03-27

    Protein adsorption to nanoparticles (NPs) is a key prerequisite to understand NP-cell interactions. While the layer thickness of the protein corona has been well characterized in many cases, the absolute number of bound proteins and their exchange dynamics in body fluids is difficult to assess. Here we measure the number of molecules adsorbed to sulfonate (PSOSO(3)H) and carboxyl-(PSCOOH) polystyrene NPs using fluorescence correlation spectroscopy. We find that the fraction of molecules bound to NPs falls onto a single, universal adsorption curve, if plotted as a function of molar protein-to-NP ratio. The adsorption curve shows the build-up of a strongly bound monolayer up to the point of monolayer saturation (at a geometrically defined protein-to-NP ratio), beyond which a secondary, weakly bound layer is formed. While the first layer is irreversibly bound (hard corona), the secondary layer (soft corona) exhibits dynamic exchange, if competing unlabeled is added. In the presence of plasma proteins, the hard corona is stable, while the soft corona is almost completely removed. The existence of two distinct time scales in the protein off-kinetics, for both NP types studied here, indicates the possibility of an exposure memory effect in the NP corona.

  4. A study of the liquid-vapor phase change of mercury based on irreversible thermodynamics.

    NASA Technical Reports Server (NTRS)

    Adt, R. R., Jr.; Hatsopoulos, G. N.; Bornhorst, W. J.

    1972-01-01

    The object of this work is to determine the transport coefficients which appear in linear irreversible-thermodynamic rate equations of a phase change. An experiment which involves the steady-state evaporation of mercury was performed to measure the principal transport coefficient appearing in the mass-rate equation and the coupling transport coefficient appearing in both the mass-rate equation and the energy-rate equation. The principal transport coefficient sigma, usually termed the 'condensation' or 'evaporation' coefficient, is found to be approximately 0.9, which is higher than that measured previously in condensation-of-mercury experiments. The experimental value of the coupling coefficient K does not agree with the value predicted from Schrage's kinetic analysis of the phase change. A modified kinetic analysis in which the Onsager reciprocal law and the conservation laws are invoked is presented which removes this discrepancy but which shows that the use of Schrage's equation for predicting mass rates of phase change is a good approximation.

  5. Single molecule analysis reveals reversible and irreversible steps during spliceosome activation

    PubMed Central

    Hoskins, Aaron A; Rodgers, Margaret L; Friedman, Larry J; Gelles, Jeff; Moore, Melissa J

    2016-01-01

    The spliceosome is a complex machine composed of small nuclear ribonucleoproteins (snRNPs) and accessory proteins that excises introns from pre-mRNAs. After assembly the spliceosome is activated for catalysis by rearrangement of subunits to form an active site. How this rearrangement is coordinated is not well-understood. During activation, U4 must be released to allow U6 conformational change, while Prp19 complex (NTC) recruitment is essential for stabilizing the active site. We used multi-wavelength colocalization single molecule spectroscopy to directly observe the key events in Saccharomyces cerevisiae spliceosome activation. Following binding of the U4/U6.U5 tri-snRNP, the spliceosome either reverses assembly by discarding tri-snRNP or proceeds to activation by irreversible U4 loss. The major pathway for NTC recruitment occurs after U4 release. ATP stimulates both the competing U4 release and tri-snRNP discard processes. The data reveal the activation mechanism and show that overall splicing efficiency may be maintained through repeated rounds of disassembly and tri-snRNP reassociation. DOI: http://dx.doi.org/10.7554/eLife.14166.001 PMID:27244240

  6. The Effect of Irreversible Electroporation on the Femur: Experimental Study in a Rabbit Model

    PubMed Central

    Song, Yue; Zheng, Jingjing; Yan, Mingwei; Ding, Weidong; Xu, Kui; Fan, Qingyu; Li, Zhao

    2015-01-01

    Irreversible electroporation (IRE) is a novel ablation method that has been tested in humans with lung, prostate, kidney, liver, lymph node and presacral cancers. As a new non-thermal treatment, the use of IRE to ablate tumors in the musculoskeletal system might reduce the incidence of fractures. We aimed to determine the ablation threshold of cortical bone and to evaluate the medium- and long-term healing process and mechanical properties of the femur in a rabbit model post-IRE ablation. The ablation threshold of cortical bone was between 1090 V/cm and 1310 V/cm (120 pulses). IRE-ablated femurs displayed no detectable fracture but did exhibit signs of recovery, including osteoblast regeneration, angiogenesis and bone remodeling. In the ablation area, revascularization appeared at 4 weeks post-IRE. Osteogenic activity peaked 8 weeks post-IRE and remained high at 12 weeks. The mechanical strength decreased briefly 4 weeks post-IRE but returned to normal levels within 8 weeks. Our experiment revealed that IRE ablation preserved the structural integrity of the bone cortex, and the ablated bone was able to regenerate rapidly. IRE may hold unique promise for in situ bone tissue ablation because rapid revascularization and active osteogenesis in the IRE ablation area are possible. PMID:26655843

  7. Electric Ablation with Irreversible Electroporation (IRE) in Vital Hepatic Structures and Follow-up Investigation.

    PubMed

    Chen, Xinhua; Ren, Zhigang; Zhu, Tongyin; Zhang, Xiongxin; Peng, Zhiyi; Xie, Haiyang; Zhou, Lin; Yin, Shengyong; Sun, Junhui; Zheng, Shusen

    2015-01-01

    Irreversible electroporation (IRE) with microsecond-pulsed electric fields (μsPEFs) can effectively ablate hepatocellular carcinomas in animal models. This preclinical study evaluates the feasibility and safety of IRE on porcine livers. Altogether, 10 pigs were included. Computed tomography (CT) was used to guide two-needle electrodes that were inserted near the hilus hepatis and gall bladder. Animals were followed-up at 2 hours and at 2, 7 and 14 days post-treatment. During and after μsPEF ablation, electrocardiographs found no cardiovascular events, and contrast CT found no portal vein thrombosis. There was necrosis in the ablation zone. Mild cystic oedema around the gall bladder was found 2 hours post-treatment. Pathological studies showed extensive cell death. There was no large vessel damage, but there was mild endothelial damage in some small vessels. Follow-up liver function tests and routine blood tests showed immediate liver function damage and recovery from the damage, which correlated to the pathological changes. These results indicate that μsPEF ablation affects liver tissue and is less effective in vessels, which enable μsPEFs to ablate central tumour lesions close to the hilus hepatis and near large vessels and bile ducts, removing some of the limitations and contraindications of conventional thermal ablation. PMID:26549662

  8. Irreversible thermodynamics of open chemical networks. I. Emergent cycles and broken conservation laws.

    PubMed

    Polettini, Matteo; Esposito, Massimiliano

    2014-07-14

    In this paper and Paper II, we outline a general framework for the thermodynamic description of open chemical reaction networks, with special regard to metabolic networks regulating cellular physiology and biochemical functions. We first introduce closed networks "in a box", whose thermodynamics is subjected to strict physical constraints: the mass-action law, elementarity of processes, and detailed balance. We further digress on the role of solvents and on the seemingly unacknowledged property of network independence of free energy landscapes. We then open the system by assuming that the concentrations of certain substrate species (the chemostats) are fixed, whether because promptly regulated by the environment via contact with reservoirs, or because nearly constant in a time window. As a result, the system is driven out of equilibrium. A rich algebraic and topological structure ensues in the network of internal species: Emergent irreversible cycles are associated with nonvanishing affinities, whose symmetries are dictated by the breakage of conservation laws. These central results are resumed in the relation a + b = s(Y) between the number of fundamental affinities a, that of broken conservation laws b and the number of chemostats s(Y). We decompose the steady state entropy production rate in terms of fundamental fluxes and affinities in the spirit of Schnakenberg's theory of network thermodynamics, paving the way for the forthcoming treatment of the linear regime, of efficiency and tight coupling, of free energy transduction, and of thermodynamic constraints for network reconstruction. PMID:25028009

  9. Mineral and bone disorders in kidney transplant recipients: reversible, irreversible, and de novo abnormalities.

    PubMed

    Hirukawa, Takashi; Kakuta, Takatoshi; Nakamura, Michio; Fukagawa, Masafumi

    2015-08-01

    Given the advances in medical technologies related to kidney transplantation, the post-transplant graft survival rate and quality of life have improved dramatically. Nevertheless, post-transplant mortality rate still remains high as compared to the general population due to the development of cardiovascular events. It has recently been widely recognized that chronic kidney disease-mineral and bone disorders (CKD-MBD) significantly contribute to such poor prognosis at least in part. In the majority of kidney recipients, abnormal serum parameters for mineral and bone disorder (MBD), such as phosphorus, calcium, 1,25-dihydroxyvitamin D, parathyroid hormone and fibroblast growth factor 23, gradually return toward acceptable levels following the re-establishment of kidney function after transplantation; however, some irreversible abnormalities, developed as the result of long-term dialysis, persist, require treatment, or even progress after kidney transplantation. Thus, better management of CKD-MBD during pre-dialysis and dialysis period as well as after kidney transplantation is highly appreciated. PMID:25931403

  10. High critical current density and enhanced irreversibility field in superconducting MgB2 thin films.

    PubMed

    Eom, C B; Lee, M K; Choi, J H; Belenky, L J; Song, X; Cooley, L D; Naus, M T; Patnaik, S; Jiang, J; Rikel, M; Polyanskii, A; Gurevich, A; Cai, X Y; Bu, S D; Babcock, S E; Hellstrom, E E; Larbalestier, D C; Rogado, N; Regan, K A; Hayward, M A; He, T; Slusky, J S; Inumaru, K; Haas, M K; Cava, R J

    2001-05-31

    The discovery of superconductivity at 39 K in magnesium diboride offers the possibility of a new class of low-cost, high-performance superconducting materials for magnets and electronic applications. This compound has twice the transition temperature of Nb3Sn and four times that of Nb-Ti alloy, and the vital prerequisite of strongly linked current flow has already been demonstrated. One possible drawback, however, is that the magnetic field at which superconductivity is destroyed is modest. Furthermore, the field which limits the range of practical applications-the irreversibility field H*(T)-is approximately 7 T at liquid helium temperature (4.2 K), significantly lower than about 10 T for Nb-Ti (ref. 6) and approximately 20 T for Nb3Sn (ref. 7). Here we show that MgB2 thin films that are alloyed with oxygen can exhibit a much steeper temperature dependence of H*(T) than is observed in bulk materials, yielding an H* value at 4.2 K greater than 14 T. In addition, very high critical current densities at 4.2 K are achieved: 1 MA cm-2 at 1 T and 105 A cm-2 at 10 T. These results demonstrate that MgB2 has potential for high-field superconducting applications.

  11. Self-regenerating and hybrid irreversible/reversible PDMS microfluidic devices.

    PubMed

    Shiroma, Letícia S; Piazzetta, Maria H O; Duarte-Junior, Gerson F; Coltro, Wendell K T; Carrilho, Emanuel; Gobbi, Angelo L; Lima, Renato S

    2016-01-01

    This paper outlines a straightforward, fast, and low-cost method to fabricate polydimethylsiloxane (PDMS) chips. Termed sandwich bonding (SWB), this method requires only a laboratory oven. Initially, SWB relies on the reversible bonding of a coverslip over PDMS channels. The coverslip is smaller than the substrate, leaving a border around the substrate exposed. Subsequently, a liquid composed of PDMS monomers and a curing agent is poured onto the structure. Finally, the cover is cured. We focused on PDMS/glass chips because of their key advantages in microfluidics. Despite its simplicity, this method created high-performance microfluidic channels. Such structures featured self-regeneration after leakages and hybrid irreversible/reversible behavior. The reversible nature was achieved by removing the cover of PDMS with acetone. Thus, the PDMS substrate and glass coverslip could be detached for reuse. These abilities are essential in the stages of research and development. Additionally, SWB avoids the use of surface oxidation, half-cured PDMS as an adhesive, and surface chemical modification. As a consequence, SWB allows surface modifications before the bonding, a long time for alignment, the enclosure of sub-micron channels, and the prototyping of hybrid devices. Here, the technique was successfully applied to bond PDMS to Au and Al. PMID:27181918

  12. A proposed approach to the application of nonlinear irreversible thermodynamics to fracture in composite materials

    NASA Technical Reports Server (NTRS)

    Lindenmeyer, P. H.

    1983-01-01

    The fracture criteria upon which most fracture mechanics is based involves an energy balance that is not appropriate for the fracture mechanics of viscoelastic materials such as polymer matrix composites. A more appropriate criterion based upon nonequilibrium thermodynamics and involving a power balance rather than an energy balance is proposed. This crierion is based upon a reformulation of the second law of thermodynamics which focuses attention on the total Legendre transform of energy expressed as a functional over time and space. This excess energy functional can be shown to be equivalent to the Rice J integral if the only irreversible process is the propogation of a single crack completely through the thickness of the specimen and if the crack propogation is assured to be independent of time. For the more general case of more than one crack in a viscoelastic medium integration over both time and space is required. Two experimentally measurable parameters are proposed which should permit the evaluation of this more general fracture criterion.

  13. Irreversible Electroporation Adjacent to the Rectum: Evaluation of Pathological Effects in a Pig Model

    SciTech Connect

    Schoellnast, Helmut; Monette, Sebastien; Ezell, Paula C.; Single, Gordon; Maybody, Majid; Weiser, Martin R.; Fong Yuman; Solomon, Stephen B.

    2013-02-15

    To evaluate the effects of irreversible electroporation (IRE) on the rectum wall after IRE applied adjacent to the rectum. CT-guided IRE adjacent to the rectum wall was performed in 11 pigs; a total of 44 lesions were created. In five pigs, ablations were performed without a water-filled endorectal coil (group A); in six pigs, ablation was performed with the coil to avoid displacement of the rectum wall (group B). The pigs were killed after 7-15 days and the rectums were harvested for pathological evaluation. There was no evidence of perforation on gross postmortem examination. Perirectal muscle lesions were observed in 18 of 20 ablations in group A and in 21 of 24 ablations in group B. Inflammation and fibrosis of the muscularis propria was observed in ten of 18 lesions in group A and in ten of 21 lesions in group B. In group A, findings were limited to the external layer of the muscularis propria except for one lesion; in group B, findings were transmural in all cases. Transmural necrosis with marked suppurative mucosal inflammation was observed in seven of 21 lesions in group B and in no lesion in group A. IRE-ablation adjacent to the rectum may be uneventful if the rectum wall is mobile and able to contract. IRE-ablation of the rectum may be harmful if the rectum wall is fixed adjacent to the IRE-probe.

  14. Tyramine antagonistic properties of AGN 1135, an irreversible inhibitor of monoamine oxidase type B.

    PubMed

    Finberg, J P; Tenne, M; Youdim, M B

    1981-05-01

    1 The effects of the irreversible monoamine oxidase (MAO) inhibitors, AGN 1133, AGN 1135 and (-)-deprenyl, on tyramine and noradrenaline responses and uptake of [3H]-metaraminol were investigated in the isolated vas deferens of the rat. Uptake of [3H]-metaraminol and [3H]-octopamine was compared in mouse vas deferens. The modification of tyramine and noradrenaline-induced pressor responses by AGN 1133 and AGN 1135 was examined in anaesthetized rats and cats. 2 AGN 1133 (7.5 x 10(-6)M) greatly potentiated responses to tyramine in the rat isolated vas deferens. Both AGN 1135 and (-)-deprenyl inhibited tyramine responses selectively at concentrations above 10(-5)M (which caused almost complete inhibition of MAO types A and B) but tyramine responses were potentiated on washing out the inhibitors. 3 AGN 1135 (10(-4)M) and (-)-deprenyl (10-5)M) inhibited [3H]-metaraminol uptake by about 20% in rat and mouse vas deferens; neither inhibitor affected [3H]-octopamine uptake in mouse vas deferens. Desmethylimipramine (10(-6)M) inhibited amine uptake by more than 70%. 4 AGN 1133 (1.5 mg/kg) potentiated pressor responses to tyramine in rats and cats whereas AGN 1135 (1.5 mg/kg) did not. 5 AGN 1135 possesses tyramine antagonistic activity which is qualitatively similar to that of (-)-deprenyl but which cannot satisfactorily be explained by inhibition of neuronal or granula amine uptake.

  15. Post-hatch heat warms adult beaks: irreversible physiological plasticity in Japanese quail

    PubMed Central

    Burness, Gary; Huard, Jacqueline R.; Malcolm, Emily; Tattersall, Glenn J.

    2013-01-01

    Across taxa, the early rearing environment contributes to adult morphological and physiological variation. For example, in birds, environmental temperature plays a key role in shaping bill size and clinal trends across latitudinal/thermal gradients. Such patterns support the role of the bill as a thermal window and in thermal balance. It remains unknown whether bill size and thermal function are reversibly plastic. We raised Japanese quail in warm (30°C) or cold (15°C) environments and then at a common intermediate temperature. We predicted that birds raised in cold temperatures would develop smaller bills than warm-reared individuals, and that regulation of blood flow to the bill in response to changing temperatures would parallel the bill's role in thermal balance. Cold-reared birds developed shorter bills, although bill size exhibited ‘catch-up’ growth once adults were placed at a common temperature. Despite having lived in a common thermal environment as adults, individuals that were initially reared in the warmth had higher bill surface temperatures than cold-reared individuals, particularly under cold conditions. This suggests that blood vessel density and/or the control over blood flow in the bill retained a memory of early thermal ontogeny. We conclude that post-hatch temperature reversibly affects adult bill morphology but irreversibly influences the thermal physiological role of bills and may play an underappreciated role in avian energetics. PMID:23884093

  16. Irreversible phase transitions in doped metal oxides as temperature sensors in explosions

    NASA Astrophysics Data System (ADS)

    Eilers, Hergen; Gunawidjaja, Ray; Myint, Thandar; Lightstone, James

    2011-06-01

    The temperature of post-detonation fireballs produced by advanced energetic formulations is commonly determined using optical methods such as pyrometry and spectral line fitting. These methods provide an average temperature mostly from the surface of the fireball. However, for many applications the ability to probe the internal temperature and temperature gradients within the fireball is highly desirable. One method that has shown promise is seeding micron to nano-sized temperature sensors into the fireball which can be collected and analyzed post-detonation. In this work, disordered Eu3+-doped nanoparticles were subjected to various heat treatments, incl. furnace, T-Jump, pulsed laser, and explosive heating. This treatment leads to irreversible phase transitions which are monitored by the Eu dopants. Optical signatures such as the ratio of electric and magnetic dipole transition intensities, energy level splitting, FWHM, etc. are evaluated to monitor the phase transitions. Also, the kinetics of particle growth is evaluated as an indicator for the time-dependence of the heating process. The information is used to establish a correlation with the temperature profile. Temperature profiles collected from a series of lab-based tests and small-scale detonations of an aluminized explosive will be presented. This work was supported by the Defense Threat Reduction Agency.

  17. Irreversible membrane fouling abatement through pre-deposited layer of hierarchical porous carbons.

    PubMed

    Hamad, Juma Z; Dua, Rubal; Kurniasari, Novita; Kennedy, Maria D; Wang, Peng; Amy, Gary L

    2014-11-15

    In this work, dual-templated hierarchical porous carbons (HPCs), produced from a coupled ice-hard templating approach, are shown to be a highly effective solution to the commonly occurring problem of irreversible fouling of low-pressure membranes used for pre-treatment in wastewater reuse. For the first time, dual-templated HPCs, along with their respective counterparts - single-templated meso-porous carbon (MPCs) (without macropores) - are tested in terms of their fouling reduction capacity and ability to remove different effluent organic matter fractions present in wastewater and compared with a commercially available powdered activated carbon (PAC). The synthesized HPCs provided exceptional fouling abatement, a 4-fold higher fouling reduction as compared to the previously reported best performing commercial PAC and ∼2.5-fold better fouling reduction than their respective mesoporous counterpart. Thus, it is shown that not only mesoporosity, but macroporosity is also necessary to achieve high fouling reduction, thus emphasizing the need for dual templating. In the case of HPCs, the pre-deposition technique is also found to outperform the traditional sorbent-feed mixing approach, mainly in terms of removal of fouling components. Based on their superior performance, a high permeability (ultra-low-pressure) membrane consisting of the synthesized HPC pre-deposited on a large pore size membrane support (0.45 μm membrane), is shown to give excellent pre-treatment performance for wastewater reuse application.

  18. Self-regenerating and hybrid irreversible/reversible PDMS microfluidic devices.

    PubMed

    Shiroma, Letícia S; Piazzetta, Maria H O; Duarte-Junior, Gerson F; Coltro, Wendell K T; Carrilho, Emanuel; Gobbi, Angelo L; Lima, Renato S

    2016-05-16

    This paper outlines a straightforward, fast, and low-cost method to fabricate polydimethylsiloxane (PDMS) chips. Termed sandwich bonding (SWB), this method requires only a laboratory oven. Initially, SWB relies on the reversible bonding of a coverslip over PDMS channels. The coverslip is smaller than the substrate, leaving a border around the substrate exposed. Subsequently, a liquid composed of PDMS monomers and a curing agent is poured onto the structure. Finally, the cover is cured. We focused on PDMS/glass chips because of their key advantages in microfluidics. Despite its simplicity, this method created high-performance microfluidic channels. Such structures featured self-regeneration after leakages and hybrid irreversible/reversible behavior. The reversible nature was achieved by removing the cover of PDMS with acetone. Thus, the PDMS substrate and glass coverslip could be detached for reuse. These abilities are essential in the stages of research and development. Additionally, SWB avoids the use of surface oxidation, half-cured PDMS as an adhesive, and surface chemical modification. As a consequence, SWB allows surface modifications before the bonding, a long time for alignment, the enclosure of sub-micron channels, and the prototyping of hybrid devices. Here, the technique was successfully applied to bond PDMS to Au and Al.

  19. Self-regenerating and hybrid irreversible/reversible PDMS microfluidic devices

    PubMed Central

    Shiroma, Letícia S.; Piazzetta, Maria H. O.; Duarte-Junior, Gerson F.; Coltro, Wendell K. T.; Carrilho, Emanuel; Gobbi, Angelo L.; Lima, Renato S.

    2016-01-01

    This paper outlines a straightforward, fast, and low-cost method to fabricate polydimethylsiloxane (PDMS) chips. Termed sandwich bonding (SWB), this method requires only a laboratory oven. Initially, SWB relies on the reversible bonding of a coverslip over PDMS channels. The coverslip is smaller than the substrate, leaving a border around the substrate exposed. Subsequently, a liquid composed of PDMS monomers and a curing agent is poured onto the structure. Finally, the cover is cured. We focused on PDMS/glass chips because of their key advantages in microfluidics. Despite its simplicity, this method created high-performance microfluidic channels. Such structures featured self-regeneration after leakages and hybrid irreversible/reversible behavior. The reversible nature was achieved by removing the cover of PDMS with acetone. Thus, the PDMS substrate and glass coverslip could be detached for reuse. These abilities are essential in the stages of research and development. Additionally, SWB avoids the use of surface oxidation, half-cured PDMS as an adhesive, and surface chemical modification. As a consequence, SWB allows surface modifications before the bonding, a long time for alignment, the enclosure of sub-micron channels, and the prototyping of hybrid devices. Here, the technique was successfully applied to bond PDMS to Au and Al. PMID:27181918

  20. A comprehensive segmentation analysis of crude oil market based on time irreversibility

    NASA Astrophysics Data System (ADS)

    Xia, Jianan; Shang, Pengjian; Lu, Dan; Yin, Yi

    2016-05-01

    In this paper, we perform a comprehensive entropic segmentation analysis of crude oil future prices from 1983 to 2014 which used the Jensen-Shannon divergence as the statistical distance between segments, and analyze the results from original series S and series begin at 1986 (marked as S∗) to find common segments which have same boundaries. Then we apply time irreversibility analysis of each segment to divide all segments into two groups according to their asymmetry degree. Based on the temporal distribution of the common segments and high asymmetry segments, we figure out that these two types of segments appear alternately and do not overlap basically in daily group, while the common portions are also high asymmetry segments in weekly group. In addition, the temporal distribution of the common segments is fairly close to the time of crises, wars or other events, because the hit from severe events to oil price makes these common segments quite different from their adjacent segments. The common segments can be confirmed in daily group series, or weekly group series due to the large divergence between common segments and their neighbors. While the identification of high asymmetry segments is helpful to know the segments which are not affected badly by the events and can recover to steady states automatically. Finally, we rearrange the segments by merging the connected common segments or high asymmetry segments into a segment, and conjoin the connected segments which are neither common nor high asymmetric.

  1. Long-term experiments to investigate irreversibility in sorption of pesticides to soil.

    PubMed

    Suddaby, L A; Beulke, S; van Beinum, W; Oliver, R G; Kuet, S; Brown, C D

    2016-11-01

    Experiments investigated irreversibility in pesticide sorption to soil. Sorption behaviour under abiotic conditions was quantified for chlorotoluron, prometryn and hexaconazole in three soils over periods of up to 274 days. An isotope-exchange procedure was used whereby sorption of (12)C- and (14)C-pesticide isotopes in shaken suspensions of three soils (56-168 days shaking) was followed by substitution of the isotopes in the liquid phase and a 14-day exchange phase. This was followed by forced isotope exchange where the sorbed (14)C material was exchanged by adding an excess of non-radiolabelled compound. Experiments were concluded with solvent extraction and soil combustion to determine remaining radioactivity. Under conditions of continuous shaking, the pesticide-soil systems took around four months to approach sorption equilibrium, resulting in strong asymmetry between the profiles of exchange for isotopes of all three compounds. Physically entrapped residues were released back into solution under the steep concentration gradient of forced isotope exchange and small amounts of radioactivity were still being released at the termination of the experiment. The profiles of exchange did not deviate markedly from ideal behaviour based on the assumption that sorption is fully reversible. Whilst the timescales for release of sorbed residues back into solution were very long, soil combustion at study termination only yielded <1-2% of applied radioactivity; this confirms that sorption processes under abiotic soil conditions were overwhelmingly reversible for this set of compounds and soils.

  2. Pretreatment with alum or powdered activated carbon reduces bacterial predation-associated irreversible fouling of membranes.

    PubMed

    Kim, Eun-Ho; Dwidar, Mohammed; Kwon, Young-Nam; Mitchell, Robert J

    2014-01-01

    This study evaluated the co-application of bacterial predation by Bdellovibrio bacteriovorus and either alum coagulation or powdered activated carbon adsorption to reduce fouling caused by Escherichia coli rich feed solutions in dead-end microfiltration tests. The flux increased when the samples were predated upon or treated with 100 ppm alum or PAC, but co-treatment with alum and predation gave the best flux results. The total membrane resistance caused by the predated sample was reduced six-fold when treated with 100 ppm PAC, from 11.8 to 1.98 × 10(11) m(-1), while irreversible fouling (Rp) was 2.7-fold lower. Treatment with 100 ppm alum reduced the total resistance 14.9-fold (11.8 to 0.79 × 10(11) m(-1)) while the Rp decreased 4.25-fold. SEM imaging confirmed this, with less obvious fouling of the membrane after the combined process. This study illustrates that the combination of bacterial predation and the subsequent removal of debris using coagulation or adsorption mitigates membrane biofouling and improves membrane performance. PMID:25410737

  3. Irreversible membrane fouling abatement through pre-deposited layer of hierarchical porous carbons.

    PubMed

    Hamad, Juma Z; Dua, Rubal; Kurniasari, Novita; Kennedy, Maria D; Wang, Peng; Amy, Gary L

    2014-11-15

    In this work, dual-templated hierarchical porous carbons (HPCs), produced from a coupled ice-hard templating approach, are shown to be a highly effective solution to the commonly occurring problem of irreversible fouling of low-pressure membranes used for pre-treatment in wastewater reuse. For the first time, dual-templated HPCs, along with their respective counterparts - single-templated meso-porous carbon (MPCs) (without macropores) - are tested in terms of their fouling reduction capacity and ability to remove different effluent organic matter fractions present in wastewater and compared with a commercially available powdered activated carbon (PAC). The synthesized HPCs provided exceptional fouling abatement, a 4-fold higher fouling reduction as compared to the previously reported best performing commercial PAC and ∼2.5-fold better fouling reduction than their respective mesoporous counterpart. Thus, it is shown that not only mesoporosity, but macroporosity is also necessary to achieve high fouling reduction, thus emphasizing the need for dual templating. In the case of HPCs, the pre-deposition technique is also found to outperform the traditional sorbent-feed mixing approach, mainly in terms of removal of fouling components. Based on their superior performance, a high permeability (ultra-low-pressure) membrane consisting of the synthesized HPC pre-deposited on a large pore size membrane support (0.45 μm membrane), is shown to give excellent pre-treatment performance for wastewater reuse application. PMID:25128660

  4. Self-regenerating and hybrid irreversible/reversible PDMS microfluidic devices

    NASA Astrophysics Data System (ADS)

    Shiroma, Letícia S.; Piazzetta, Maria H. O.; Duarte-Junior, Gerson F.; Coltro, Wendell K. T.; Carrilho, Emanuel; Gobbi, Angelo L.; Lima, Renato S.

    2016-05-01

    This paper outlines a straightforward, fast, and low-cost method to fabricate polydimethylsiloxane (PDMS) chips. Termed sandwich bonding (SWB), this method requires only a laboratory oven. Initially, SWB relies on the reversible bonding of a coverslip over PDMS channels. The coverslip is smaller than the substrate, leaving a border around the substrate exposed. Subsequently, a liquid composed of PDMS monomers and a curing agent is poured onto the structure. Finally, the cover is cured. We focused on PDMS/glass chips because of their key advantages in microfluidics. Despite its simplicity, this method created high-performance microfluidic channels. Such structures featured self-regeneration after leakages and hybrid irreversible/reversible behavior. The reversible nature was achieved by removing the cover of PDMS with acetone. Thus, the PDMS substrate and glass coverslip could be detached for reuse. These abilities are essential in the stages of research and development. Additionally, SWB avoids the use of surface oxidation, half-cured PDMS as an adhesive, and surface chemical modification. As a consequence, SWB allows surface modifications before the bonding, a long time for alignment, the enclosure of sub-micron channels, and the prototyping of hybrid devices. Here, the technique was successfully applied to bond PDMS to Au and Al.

  5. Irreversible adsorption of atmospheric helium on olivine: A lobster pot analogy

    NASA Astrophysics Data System (ADS)

    Protin, Marie; Blard, Pierre-Henri; Marrocchi, Yves; Mathon, François

    2016-04-01

    This study reports new experimental results that demonstrate that large amounts of atmospheric helium may be adsorbed onto the surfaces of olivine grains. This behavior is surface-area-related in that this contamination preferentially affects grains that are smaller than 125 μm in size. One of the most striking results of our study is that in vacuo heating at 900 °C for 15 min is not sufficient to completely remove the atmospheric contamination. This suggests that the adsorption of helium may involve high-energy trapping of helium through irreversible anomalous adsorption. This trapping process of helium can thus be compared to a "lobster pot" adsorption: atmospheric helium easily gets in, but hardly gets out. While this type of behavior has previously been reported for heavy noble gases (Ar, Kr, Xe), this is the first time that it has been observed for helium. Adsorption of helium has, until now, generally been considered to be negligible on silicate surfaces. Our findings have significant implications for helium and noble gas analysis of natural silicate samples, such as for cosmic-ray exposure dating or noble gas characterization of extraterrestrial material. Analytical procedures in future studies should be adapted in order to avoid this contamination. The results of this study also allow us to propose an alternative explanation for previously described matrix loss of cosmogenic 3He.

  6. Efficiency at maximum power of a quantum Otto cycle within finite-time or irreversible thermodynamics.

    PubMed

    Wu, Feilong; He, Jizhou; Ma, Yongli; Wang, Jianhui

    2014-12-01

    We consider the efficiency at maximum power of a quantum Otto engine, which uses a spin or a harmonic system as its working substance and works between two heat reservoirs at constant temperatures T(h) and T(c) (irreversible thermodynamics, we calculate the Onsager coefficients and show that the value of η(CA) is indeed the upper bound of EMP for an Otto engine working in the linear-response regime.

  7. Irreversible thermodynamics of open chemical networks. I. Emergent cycles and broken conservation laws

    SciTech Connect

    Polettini, Matteo Esposito, Massimiliano

    2014-07-14

    In this paper and Paper II, we outline a general framework for the thermodynamic description of open chemical reaction networks, with special regard to metabolic networks regulating cellular physiology and biochemical functions. We first introduce closed networks “in a box”, whose thermodynamics is subjected to strict physical constraints: the mass-action law, elementarity of processes, and detailed balance. We further digress on the role of solvents and on the seemingly unacknowledged property of network independence of free energy landscapes. We then open the system by assuming that the concentrations of certain substrate species (the chemostats) are fixed, whether because promptly regulated by the environment via contact with reservoirs, or because nearly constant in a time window. As a result, the system is driven out of equilibrium. A rich algebraic and topological structure ensues in the network of internal species: Emergent irreversible cycles are associated with nonvanishing affinities, whose symmetries are dictated by the breakage of conservation laws. These central results are resumed in the relation a + b = s{sup Y} between the number of fundamental affinities a, that of broken conservation laws b and the number of chemostats s{sup Y}. We decompose the steady state entropy production rate in terms of fundamental fluxes and affinities in the spirit of Schnakenberg's theory of network thermodynamics, paving the way for the forthcoming treatment of the linear regime, of efficiency and tight coupling, of free energy transduction, and of thermodynamic constraints for network reconstruction.

  8. Irreversible muscle damage in bodybuilding due to long-term intramuscular oil injection.

    PubMed

    Banke, I J; Prodinger, P M; Waldt, S; Weirich, G; Holzapfel, B M; Gradinger, R; Rechl, H

    2012-10-01

    Intramuscular oil injections generating slowly degrading oil-based depots represent a controversial subject in bodybuilding and fitness. However they seem to be commonly reported in a large number of non-medical reports, movies and application protocols for 'site-injections'. Surprisingly the impact of long-term (ab)use on the musculature as well as potential side-effects compromising health and sports ability are lacking in the medical literature. We present the case of a 40 year old male semi-professional bodybuilder with systemic infection and painful reddened swellings of the right upper arm forcing him to discontinue weightlifting. Over the last 8 years he daily self-injected sterilized sesame seed oil at numerous intramuscular locations for the purpose of massive muscle building. Whole body MRI showed more than 100 intramuscular rather than subcutaneous oil cysts and loss of normal muscle anatomy. 2-step septic surgery of the right upper arm revealed pus-filled cystic scar tissue with the near-complete absence of normal muscle. MRI 1 year later revealed the absence of relevant muscle regeneration. Persistent pain and inability to perform normal weight training were evident for at least 3 years post-surgery. This alarming finding indicating irreversible muscle mutilation may hopefully discourage people interested in bodybuilding and fitness from oil-injections. The impact of such chronic tissue stress on other diseases like malignancy remains to be determined.

  9. The irreversible binding of amyloid peptide substrates to insulin-degrading enzyme

    PubMed Central

    de Tullio, Matías B; Morelli, Laura

    2008-01-01

    Insulin-degrading enzyme (IDE) is a conserved Zn2+metalloendopeptidase involved in insulin degradation and in the maintenance of brain steady-state levels of amyloid β peptide (Aβ) of Alzheimer's disease (AD). Our recent demonstration that IDE and Aβ are capable of forming a stoichiometric and extremely stable complex raises several intriguing possibilities regarding the role of this unique protein-peptide interaction in physiological and pathological conditions. These include a protective cellular function of IDE as a “dead-end chaperone” alternative to its proteolytic activity and the potential impact of the irreversible binding of Aβ to IDE upon its role as a varicella zoster virus receptor. In a pathological context, the implications for insulin signaling and its relationship to AD pathogenesis are discussed. Moreover, our findings warrant further research regarding a possible general and novel interaction between amyloidogenic peptides and other Zn2+metallopeptidases with an IDE-like fold and a substrate conformation-dependent recognition mechanism. PMID:19098445

  10. Traffic time series analysis by using multiscale time irreversibility and entropy.

    PubMed

    Wang, Xuejiao; Shang, Pengjian; Fang, Jintang

    2014-09-01

    Traffic systems, especially urban traffic systems, are regulated by different kinds of interacting mechanisms which operate across multiple spatial and temporal scales. Traditional approaches fail to account for the multiple time scales inherent in time series, such as empirical probability distribution function and detrended fluctuation analysis, which have lead to different results. The role of multiscale analytical method in traffic time series is a frontier area of investigation. In this paper, our main purpose is to introduce a new method-multiscale time irreversibility, which is helpful to extract information from traffic time series we studied. In addition, to analyse the complexity of traffic volume time series of Beijing Ring 2, 3, 4 roads between workdays and weekends, which are from August 18, 2012 to October 26, 2012, we also compare the results by this new method and multiscale entropy method we have known well. The results show that the higher asymmetry index we get, the higher traffic congestion level will be, and accord with those which are obtained by multiscale entropy. PMID:25273180

  11. The feasibility of using irreversible electroporation to introduce pores in bacterial cellulose scaffolds for tissue engineering.

    PubMed

    Baah-Dwomoh, Adwoa; Rolong, Andrea; Gatenholm, Paul; Davalos, Rafael V

    2015-06-01

    This work investigates the feasibility of the use of irreversible electroporation (IRE) in the biofabrication of 3D cellulose nanofibril networks via the bacterial strain Gluconacetobacter xylinus. IRE uses electrical pulses to increase membrane permeability by altering the transmembrane potential; past a threshold, damage to the cell becomes too great and leads to cell death. We hypothesized that using IRE to kill the bacteria at specific locations and particular times, we could introduce conduits in the overall scaffold by preventing cellulose biosynthesis locally. Through mathematical modeling and experimental techniques, electrical effects were investigated and the parameters for IRE of G. xylinus were determined. We found that for a specific set of parameters, an applied electric field of 8 to 12.5 kV/cm, producing a local field of 3 kV/cm, was sufficient to kill most of the bacteria and create a localized pore. However, an applied electric field of 17.5 kV/cm was required to kill all. Results suggest that IRE may be an effective tool to create scaffolds with appropriate porosity for orthopedic applications. Ideally, these engineered scaffolds could be used to successfully treat osteochondral defects. PMID:25690311

  12. Irreversible binding of an anticancer compound (BI-94) to plasma proteins

    PubMed Central

    Gautam, Nagsen; Thakare, Rhishikesh; Rana, Sandeep; Natarajan, Amarnath; Alnouti, Yazen

    2015-01-01

    1. We investigated the mechanisms responsible for the in vivo instability of a benzofurazan compound BI-94 (NSC228148) with potent anti-cancer activity. 2. BI-94 was stable in MeOH, water, and in various buffers at pHs 2.5–5, regardless of the buffer composition. In contrast, BI-94 was unstable in NaOH and at pHs 7–9, regardless of the buffer composition. BI-94 disappeared immediately after spiking into mice, rat, monkey, and human plasma. BI-94 stability in plasma can be only partially restored by acidifying it, which indicated other mechanisms in addition to pH for BI-94 instability in plasma. 3. BI-94 formed adducts with the trapping agents, glutathione (GSH) and N-acetylcysteine (NAC), in vivo and in vitro via nucleophilic aromatic substitution reaction. The kinetics of adduct formation showed that neutral or physiological pHs enhanced and accelerated GSH and NAC adduct formation with BI-94, whereas acidic pHs prevented it. Therefore, physiological pHs not only altered BI-94 chemical stability but also enhanced adduct formation with endogenous nucleophiles. In addition, adduct formation with human serum albumin-peptide 3 (HSA-T3) at the Cys34 position was demonstrated. 4. In conclusion, BI-94 was unstable at physiological conditions due to chemical instability and irreversible binding to plasma proteins. PMID:25869245

  13. Irreversible and reversible reactive chromatography: analytical solutions and moment analysis for rectangular pulse injections.

    PubMed

    Bibi, Sameena; Qamar, Shamsul; Seidel-Morgenstern, Andreas

    2015-03-13

    This work is concerned with the analysis of models for linear reactive chromatography describing irreversible A→B and reversible A↔B reactions. In contrast to previously published results rectangular reactant pulses are injected into initially empty or pre-equilibrated columns assuming both Dirichlet and Danckwerts boundary conditions. The models consist of two partial differential equations, accounting for convection, longitudinal dispersion and first order chemical reactions. Due to the effect of involved mechanisms on solute transport, analytical and numerical solutions of the models could be helpful to understand, design and optimize chromatographic reactors. The Laplace transformation is applied to solve the model equations analytically for linear adsorption isotherms. Statistical temporal moments are derived from solutions in the Laplace domain. Analytical results are compared with numerical predictions generated using a high-resolution finite volume scheme for two sets of boundary conditions. Several case studies are carried out to analyze reactive liquid chromatographic processes for a wide range of mass transfer and reaction kinetics. Good agreements in the results validate the correctness of the analytical solutions and accuracy of the proposed numerical algorithm.

  14. Irreversible binding of biologically reduced 2,4,6-trinitrotoluene to soil

    SciTech Connect

    Achtnich, C.; Sieglen, U.; Knackmuss, H.J.; Lenke, H.

    1999-11-01

    To analyze the fate of 2,4,6-trinitrotoluene (TNT) and its reduction products, a TNT-contaminated soil was spiked with [ring-UL-{sup 14}C]TNT and treated in a laboratory slurry reactor. During an anaerobic/aerobic treatment, the total radioactivity measured in the supernatant and methanolic soil extracts decreased to 2%. The decrease corresponded to an increase of strongly bound radioactivity to the soil. Throughout the whole treatment process, mineralization of TNT was not observed. During the reductive process, unidentified polar substances increased to a maximum amount of 23.2% of the total radioactivity on the day after the start of the experiment. After the end of the anaerobic phase, still 9.7% of the radioactivity was found in this fraction. Only during the aerobic phase did the polar substances disappear completely. The irreversible character of the binding of the reduced metabolites of TNT to the soil was indicated by the failure of desorption even under rigorous and long-term extraction conditions. A significant release of radioactivity could be measured only by using high concentrations of HCl or EDTA. However, in none of the extracts were TNT or any reduced metabolites detected by HPLC and {sup 14}C-radiocounting. Size-exclusion chromatography of humic acids extracted from the treated soil indicated that the metabolites of TNT were evenly bound to the complete range of molecular size of the humic acids.

  15. Irreversible thermodynamics of open chemical networks. I. Emergent cycles and broken conservation laws

    NASA Astrophysics Data System (ADS)

    Polettini, Matteo; Esposito, Massimiliano

    2014-07-01

    In this paper and Paper II, we outline a general framework for the thermodynamic description of open chemical reaction networks, with special regard to metabolic networks regulating cellular physiology and biochemical functions. We first introduce closed networks "in a box", whose thermodynamics is subjected to strict physical constraints: the mass-action law, elementarity of processes, and detailed balance. We further digress on the role of solvents and on the seemingly unacknowledged property of network independence of free energy landscapes. We then open the system by assuming that the concentrations of certain substrate species (the chemostats) are fixed, whether because promptly regulated by the environment via contact with reservoirs, or because nearly constant in a time window. As a result, the system is driven out of equilibrium. A rich algebraic and topological structure ensues in the network of internal species: Emergent irreversible cycles are associated with nonvanishing affinities, whose symmetries are dictated by the breakage of conservation laws. These central results are resumed in the relation a + b = sY between the number of fundamental affinities a, that of broken conservation laws b and the number of chemostats sY. We decompose the steady state entropy production rate in terms of fundamental fluxes and affinities in the spirit of Schnakenberg's theory of network thermodynamics, paving the way for the forthcoming treatment of the linear regime, of efficiency and tight coupling, of free energy transduction, and of thermodynamic constraints for network reconstruction.

  16. Electronic structure, irreversibility line and magnetoresistance of Cu0.3Bi2Se3 superconductor

    DOE PAGES

    Hemian, Yi; Gu, Genda; Chen, Chao -Yu; Sun, Xuan; Xie, Zhuo -Jin; Feng, Ya; Liang, Ai -Ji; Peng, Ying -Ying; He, Shao -Long; Zhao, Lin; et al

    2015-06-01

    CuxBi2Se3 is a superconductor that is a potential candidate for topological superconductors. We report our laser-based angle-resolved photoemission measurement on the electronic structure of the CuxBi2Se3 superconductor, and a detailed magneto-resistance measurement in both normal and superconducting states. We find that the topological surface state of the pristine Bi2Se3 topological insulator remains robust after the Cu-intercalation, while the Dirac cone location moves downward due to electron doping. Detailed measurements on the magnetic field-dependence of the resistance in the superconducting state establishes an irreversibility line and gives a value of the upper critical field at zero temperature of ~4000 Oe formore » the Cu0.3Bi2Se3 superconductor with a middle point Tc of 1.9K. The relation between the upper critical field Hc2 and temperature T is different from the usual scaling relation found in cuprates and in other kinds of superconductors. Small positive magneto-resistance is observed in Cu0.3Bi2Se3 superconductors up to room temperature. As a result, these observations provide useful information for further study of this possible candidate for topological superconductors.« less

  17. Irreversible thermodynamics of open chemical networks. I. Emergent cycles and broken conservation laws.

    PubMed

    Polettini, Matteo; Esposito, Massimiliano

    2014-07-14

    In this paper and Paper II, we outline a general framework for the thermodynamic description of open chemical reaction networks, with special regard to metabolic networks regulating cellular physiology and biochemical functions. We first introduce closed networks "in a box", whose thermodynamics is subjected to strict physical constraints: the mass-action law, elementarity of processes, and detailed balance. We further digress on the role of solvents and on the seemingly unacknowledged property of network independence of free energy landscapes. We then open the system by assuming that the concentrations of certain substrate species (the chemostats) are fixed, whether because promptly regulated by the environment via contact with reservoirs, or because nearly constant in a time window. As a result, the system is driven out of equilibrium. A rich algebraic and topological structure ensues in the network of internal species: Emergent irreversible cycles are associated with nonvanishing affinities, whose symmetries are dictated by the breakage of conservation laws. These central results are resumed in the relation a + b = s(Y) between the number of fundamental affinities a, that of broken conservation laws b and the number of chemostats s(Y). We decompose the steady state entropy production rate in terms of fundamental fluxes and affinities in the spirit of Schnakenberg's theory of network thermodynamics, paving the way for the forthcoming treatment of the linear regime, of efficiency and tight coupling, of free energy transduction, and of thermodynamic constraints for network reconstruction.

  18. In vivo non-thermal irreversible electroporation impact on rat liver galvanic apparent internal resistance.

    PubMed

    Golberg, A; Laufer, S; Rabinowitch, H D; Rubinsky, B

    2011-02-21

    Non-thermal irreversible electroporation (NTIRE) is a biophysical phenomenon which involves application of electric field pulses to cells or tissues, causing certain rearrangements in the membrane structure leading to cell death. The treated tissue ac impedance changes induced by electroporation were shown to be the indicators for NTIRE efficiency. In a previous study we characterized in vitro tissue galvanic apparent internal resistance (GAIR) changes due to NTIRE. Here we describe an in vivo study in which we monitored the GAIR changes of a rat liver treated by NTIRE. Electrical pulses were delivered through the same Zn/Cu electrodes by which GAIR was measured. GAIR was measured before and for 3 h after the treatment at 15 min intervals. The results were compared to the established ac bioimpedance measurement method. A decrease of 33% was measured immediately after the NTIRE treatment and a 40% decrease was measured after 3 h in GAIR values; in the same time 40% and 47% decrease respectively were measured by ac bioimpedance analyses. The temperature increase due to the NTIRE was only 0.5 °C. The results open the way for an inexpensive, self-powered in vivo real-time NTIRE effectiveness measurement.

  19. Irreversible electroporation and apoptosis in human liver cancer cells induced by nanosecond electric pulses.

    PubMed

    Xiao, Deyou; Yao, Chenguo; Liu, Huan; Li, Chengxiang; Cheng, Jie; Guo, Fei; Tang, Liling

    2013-10-01

    The goal of this study was to assess the effect of nanosecond electric pulses on HepG2 human liver cancer cells. Electric pulses with a high strength of 10 kV/cm, duration of 500 ns and frequency of 1 Hz were applied to the cells. After delivery of electric pulses, apoptosis, intracellular calcium ion concentrations, transmembrane mitochondrial potentials, electropermeabilization and recovery from electropermeabilization in cells were investigated. The results showed that electric pulse treatment for 20 s and more could trigger apoptosis in cells. Real-time observation indicated an immediate increase in intracellular calcium ion concentration and a dramatic decrease in mitochondrial membrane potential in cells responding to electric pulses. In subsequent experiments, propidium iodide uptake in cells emerged after exposure to electric pulses, indicating electropermeabilization of the cell membrane. Furthermore, recovery from electropermeabilization was not observed even 4 h after the stimulation, demonstrating that irreversible electropermeabilization was induced by electric pulses. In conclusion, electric pulses with a high strength and nanosecond duration can damage cancer cells, accompanied by a series of intracellular changes, providing strong evidence for the application of electric pulses in cancer treatment. PMID:23740887

  20. Magnetization of underdoped YBa2Cu3Oy above the irreversibility field

    NASA Astrophysics Data System (ADS)

    Yu, Jing Fei; Ramshaw, B. J.; Kokanović, I.; Modic, K. A.; Harrison, N.; Day, James; Liang, Ruixing; Hardy, W. N.; Bonn, D. A.; McCollam, A.; Julian, S. R.; Cooper, J. R.

    2015-11-01

    Torque magnetization measurements on YBa2Cu3Oy (YBCO) at doping y =6.67 (p =0.12 ), in dc fields (B ) up to 33 T and temperatures down to 4.5 K, show that weak diamagnetism persists above the extrapolated irreversibility field Hirr(T =0 ) ≈24 T. The differential susceptibility d M /d B , however, is more rapidly suppressed for B ≳16 T than expected from the properties of the low field superconducting state, and saturates at a low value for fields B ≳24 T. In addition, torque measurements on a p =0.11 YBCO crystal in pulsed field up to 65 T and temperatures down to 8 K show similar behavior, with no additional features at higher fields. We offer two candidate scenarios to explain these observations: (a) superconductivity survives but is heavily suppressed at high field by competition with charge-density-wave (CDW) order; (b) static superconductivity disappears near 24 T and is followed by a region of fluctuating superconductivity, which causes d M /d B to saturate at high field. The diamagnetic signal observed above 50 T for the p =0.11 crystal at 40 K and below may be caused by changes in the normal state susceptibility rather than bulk or fluctuating superconductivity. There will be orbital (Landau) diamagnetism from electron pockets and possibly a reduction in spin susceptibility caused by the stronger three-dimensional ordered CDW.

  1. Efficiency at maximum power of a quantum Otto cycle within finite-time or irreversible thermodynamics

    NASA Astrophysics Data System (ADS)

    Wu, Feilong; He, Jizhou; Ma, Yongli; Wang, Jianhui

    2014-12-01

    We consider the efficiency at maximum power of a quantum Otto engine, which uses a spin or a harmonic system as its working substance and works between two heat reservoirs at constant temperatures Th and Tc (irreversible thermodynamics, we calculate the Onsager coefficients and show that the value of ηCA is indeed the upper bound of EMP for an Otto engine working in the linear-response regime.

  2. Pressure-Induced Irreversible Phase Transition in the Energetic Material Urea Nitrate

    NASA Astrophysics Data System (ADS)

    Li, Shourui; Zou, Bo

    2013-06-01

    The behavior of energetic material Urea Nitrate ((NH2)2 COH+ . NO3-,UN) has been investigated up to the pressure of ~26 GPa. UN exhibits the typical supramolecular structure with uronium cation and nitrate anion held together by multiple hydrogen bonds in the layer. Both Raman and XRD data provide obvious evidence for the distorted phase transition in the pressure range ~9-15 GPa. Further analysis indicates phase II has Pc symmetry. The mechanism for the phase transition involves collapse of the initial 2D supramolecular structure to 3D hydrogen-bonded networks in phase Pc. Importantly, the transition is irreversible and leads to a large reduction in volume on release of pressure. The density in phase Pc has been increased by ~11.8% compared to the phase P21/ c under ambient conditions and therefore phase Pc is expected to have much higher detonation power. This study opens new opportunities for preparing energetic materials with high density combining supramolecular chemistry with high-pressure techniques. Corresponding author. E-mail: zoubo@jlu.edu.cn This work is supported by National Science Foundation of China (NSFC) (Nos. 91227202, and 21073071).

  3. Langmuirian Blocking of Irreversible Colloid Retention: Analytical Solution, Moments, and Setback Distance.

    PubMed

    Leij, Feike J; Bradford, Scott A; Wang, Yusong; Sciortino, Antonella

    2015-09-01

    Soil and aquifer materials have a finite capacity for colloid retention. Blocking of the limited number of available retention sites further decreases the rate of retention with time and enhances risks (e.g., pathogens or colloid-associated contaminants) or benefits (e.g., remediation by microorganisms or nanoparticles) of colloid migration. Our objective was to use a straightforward procedure, based on variable transformation and Laplace transform, to solve the problem of advective colloid transport with irreversible retention and Langmuirian blocking for a pulse-type condition. Formulas for the mean breakthrough time and retardation factor were obtained using zero- and first-order time moments of the breakthrough curves. Equations for the time and position (setback distance) for a particular colloid concentration were obtained from this information. D21 g breakthrough curves and retention profiles in fine sand at four ionic strengths were well described by the model when parameters were optimized. Illustrative simulations demonstrated that blocking becomes more important for smaller retention capacity () and for larger retention rate coefficient (), input concentration (), and pulse duration. Blocking tended to delay colloid arrival time at a particular location relative to a conservative tracer, and produced larger setback distances for smaller and /.

  4. The Feasibility of Using Irreversible Electroporation to Introduce Pores in Bacterial Cellulose Scaffolds for Tissue Engineering

    PubMed Central

    Baah-Dwomoh, Adwoa; Rolong, Andrea; Gatenholm, Paul; Davalos, Rafael V.

    2015-01-01

    This work investigates the feasibility of the use of irreversible electroporation (IRE) in the biofabrication of 3D cellulose nanofibril networks via the bacterial strain Gluconacetobacter xylinus. IRE uses electrical pulses to increase membrane permeability by altering the transmembrane potential; past a threshold, damage to the cell becomes too great and leads to cell death. We hypothesized that using IRE to kill the bacteria at specific locations and particular times, we could introduce conduits in the overall scaffold by preventing cellulose biosynthesis locally. Through mathematical modeling and experimental techniques, electrical effects were investigated and the parameters for IRE of Gluconacetobacter xylinus were determined. We found that for a specific set of parameters, an applied electric field of 8 kV/cm to 12.5 kV/cm was sufficient to kill bacteria and create a localized pore. We also found that an applied electric field of 8 kV/cm to 12.5 kV/cm, which produces a local field of 3 kV/cm was sufficient to kill most of the bacteria and produce a localized pore, but an applied electric field of 17.5 kV/cm was required to kill all. Results suggest that IRE may be an effective tool to create scaffolds with appropriate porosity for orthopedic applications. Ideally, these engineered scaffolds could be used to successfully treat osteochondral defects. PMID:25690311

  5. The feasibility of using irreversible electroporation to introduce pores in bacterial cellulose scaffolds for tissue engineering.

    PubMed

    Baah-Dwomoh, Adwoa; Rolong, Andrea; Gatenholm, Paul; Davalos, Rafael V

    2015-06-01

    This work investigates the feasibility of the use of irreversible electroporation (IRE) in the biofabrication of 3D cellulose nanofibril networks via the bacterial strain Gluconacetobacter xylinus. IRE uses electrical pulses to increase membrane permeability by altering the transmembrane potential; past a threshold, damage to the cell becomes too great and leads to cell death. We hypothesized that using IRE to kill the bacteria at specific locations and particular times, we could introduce conduits in the overall scaffold by preventing cellulose biosynthesis locally. Through mathematical modeling and experimental techniques, electrical effects were investigated and the parameters for IRE of G. xylinus were determined. We found that for a specific set of parameters, an applied electric field of 8 to 12.5 kV/cm, producing a local field of 3 kV/cm, was sufficient to kill most of the bacteria and create a localized pore. However, an applied electric field of 17.5 kV/cm was required to kill all. Results suggest that IRE may be an effective tool to create scaffolds with appropriate porosity for orthopedic applications. Ideally, these engineered scaffolds could be used to successfully treat osteochondral defects.

  6. Susceptibility of the early Earth to irreversible glaciation caused by carbon dioxide clouds.

    PubMed

    Caldeira, K; Kasting, J F

    1992-09-17

    Simple energy-balance climate models of the Budyko/Sellers type predict that a small (2-5%) decrease in solar output could result in runaway glaciation on the Earth. But solar fluxes 25-30% lower early in the Earth's history apparently did not lead to this result. One currently favoured explanation is that high partial pressures of carbon dioxide, caused by higher volcanic outgassing rates and/or slower rates of silicate weathering, created a large enough greenhouse effect to keep the planet warm. This does not resolve the problem of climate stability, however, because as we argue here, the oceans can freeze much more quickly than CO2 can accumulate in the atmosphere. Had such a transient global glaciation occurred in the distant past when solar luminosity was low, it might have been irreversible because of the formation of highly reflective CO2 clouds, similar to those encountered in climate simulations of early Mars. Our simulations of the early Earth, incorporating the possible formation of such clouds, suggest that the Earth might not be habitable today had it not been warm during the first part of its history. PMID:11540934

  7. Proton-driven spin diffusion in rotating solids via reversible and irreversible quantum dynamics

    PubMed Central

    Veshtort, Mikhail; Griffin, Robert G.

    2011-01-01

    Proton-driven spin diffusion (PDSD) experiments in rotating solids have received a great deal of attention as a potential source of distance constraints in large biomolecules. However, the quantitative relationship between the molecular structure and observed spin diffusion has remained obscure due to the lack of an accurate theoretical description of the spin dynamics in these experiments. We start with presenting a detailed relaxation theory of PDSD in rotating solids that provides such a description. The theory applies to both conventional and radio-frequency-assisted PDSD experiments and extends to the non-Markovian regime to include such phenomena as rotational resonance (R2). The basic kinetic equation of the theory in the non-Markovian regime has the form of a memory function equation, with the role of the memory function played by the correlation function. The key assumption used in the derivation of this equation expresses the intuitive notion of the irreversible dissipation of coherences in macroscopic systems. Accurate expressions for the correlation functions and for the spin diffusion constants are given. The theory predicts that the spin diffusion constants governing the multi-site PDSD can be approximated by the constants observed in the two-site diffusion. Direct numerical simulations of PDSD dynamics via reversible Liouville-von Neumann equation are presented to support and compliment the theory. Remarkably, an exponential decay of the difference magnetization can be observed in such simulations in systems consisting of only 12 spins. This is a unique example of a real physical system whose typically macroscopic and apparently irreversible behavior can be traced via reversible microscopic dynamics. An accurate value for the spin diffusion constant can be usually obtained through direct simulations of PDSD in systems consisting of two 13C nuclei and about ten 1H nuclei from their nearest environment. Spin diffusion constants computed by this method

  8. Evolution of host specificity in fleas: is it directional and irreversible?

    PubMed

    Poulin, Robert; Krasnov, Boris R; Shenbrot, Georgy I; Mouillot, David; Khokhlova, Irina S

    2006-02-01

    Evolutionary trends in the evolution of host specificity have been the focus of much discussion but little rigorous empirical testing. On the one hand, specialization is often presumed to lead irreversibly into evolutionary dead ends and little diversification; this would mean that generalists might evolve into specialists, but not vice versa. On the other hand, low host specificity may limit the risk of extinction and provide more immediate fitness benefits to parasites, such that selection may favour evolution toward a generalist strategy. Here, we test for directionality in the evolution of host specificity using a large data set and phylogenetic information on 297 species of fleas parasitic on small mammals. The analyses determined whether host specificity, measured both as the number of host species exploited and their taxonomic diversity, was related to clade rank of the flea species, or the number of branching events between an extant species and the root of the phylogenetic tree (i.e., the total path length from the root of the tree to the species). Based on regression analyses, we found positive relationships between the number of host species used and clade rank across all 297 species, as well as within one (Hystrichopsyllidae) of four large families and one of seven large genera investigated separately; in addition, we found a positive relationship between the taxonomic diversity of host species used and clade rank in another of the seven genera. These results suggest a slight evolutionary trend of decreasing host specificity. Using a much more conservative likelihood ratio test, however, a random walk, or null model, of evolution could not be discarded in favour of the directional trends in all cases mentioned above. Still, these results suggest that host specificity may have tended to decrease in many flea lineages, a process that could have been driven by the benefits of exploiting a wide range of host species.

  9. Effects of irreversible electroporation on cervical cancer cell lines in vitro.

    PubMed

    Qin, Qin; Xiong, Zheng-Ai; Liu, Ying; Yao, Chen-Guo; Zhou, Wei; Hua, Yuan-Yuan; Wang, Zhi-Liang

    2016-09-01

    The effects of irreversible electroporation (IRE) on the proliferation, migration, invasion and adhesion of human cervical cancer cell lines HeLa and SiHa were investigated in the present study. HeLa and SiHa cells were divided into a treatment group and control group. The treatment group cells were exposed to electric pulses at 16 pulses, 1 Hz frequency for 100 µsec with 1,000 V/cm strength. Cellular proliferation was determined 24 h after treatment using a Cell Counting Kit‑8 (CCK‑8) assay and carboxyfluorescein diacetate‑succinimidyl ester (CFDA‑SE) labeling assay. The different phases of the cell cycle were detected using flow cytometry. Wound healing, Transwell invasion and Matrigel adhesion assays were performed to evaluate the migration, invasion and adhesion abilities of HeLa and SiHa cells. The expression levels of metastasis‑associated proteins were determined by western blot analysis. CCK‑8 and CFSE labeling assays indicated that the inhibition of cellular proliferation occurs in cells treated with IRE. Additionally, cell cycle progression was arrested at the G1/S phase. A western blot analysis indicated that the expression levels of p53 and p21 proteins were increased, whilst those of cyclin‑dependent kinase 2 (CDK2) and proliferating cell nuclear antigen (PCNA) proteins were decreased. However, wound healing, invasion and adhesion assays indicated that cellular migration, invasion and adhesion abilities were not significantly altered following exposure to IRE. IRE was not observed to promote the migration, invasion or adhesion capacity of HeLa and SiHa cells. However, IRE may inhibit the capacity of cells to proliferate and their progression through the cell cycle in vitro. Preliminary evidence suggests that the underlying mechanism involves increased expression levels of p53 and p21 and decreased expression levels of CDK2 and PCNA. PMID:27431825

  10. Improved local and systemic anti-tumor efficacy for irreversible electroporation in immunocompetent versus immunodeficient mice.

    PubMed

    Neal, Robert E; Rossmeisl, John H; Robertson, John L; Arena, Christopher B; Davis, Erica M; Singh, Ravi N; Stallings, Jonathan; Davalos, Rafael V

    2013-01-01

    Irreversible electroporation (IRE) is a non-thermal focal ablation technique that uses a series of brief but intense electric pulses delivered into a targeted region of tissue, killing the cells by irrecoverably disrupting cellular membrane integrity. This study investigates if there is an improved local anti-tumor response in immunocompetent (IC) BALB/c versus immunodeficient (ID) nude mice, including the potential for a systemic protective effect against rechallenge. Subcutaneous murine renal carcinoma tumors were treated with an IRE pulsing protocol that used 60% of the predicted voltage required to invoke complete regressions in the ID mice. Tumors were followed for 34 days following treatment for 11 treated mice from each strain, and 7 controls from each strain. Mouse survival based on tumor burden and the progression-free disease period was substantially longer in the treated IC mice relative to the treated ID mice and sham controls for both strains. Treated IC mice were rechallenged with the same cell line 18 days after treatment, where growth of the second tumors was shown to be significantly reduced or prevented entirely. There was robust CD3+ cell infiltration in some treated BALB/C mice, with immunocytes focused at the transition between viable and dead tumor. There was no difference in the low immunocyte presence for untreated tumors, nude mice, and matrigel-only injections in both strains. These findings suggest IRE therapy may have greater therapeutic efficacy in immunocompetent patients than what has been suggested by immunodeficient models, and that IRE may invoke a systemic response beyond the targeted ablation region. PMID:23717630

  11. Photoaffinity labelling of MSH receptors on Anolis melanophores: irradiation technique and MSH photolabels for irreversible stimulation

    SciTech Connect

    Eberle, A.N.

    1984-01-01

    Excised dorsal skin of Anolis carolinensis was exposed to high intensity UV-irradiation in the presence of different photoreactive alpha-MSH derivatives. The resulting covalent binding of the hormone to its receptor induced irreversible pigment dispersion. The duration of the longlasting response depended on the type and length of irradiation; it was maximal after two 5 min irradiation phases with a light intensity of approximately 180 mW/cm/sup 2/ and a spectrum from 310 to 550 nm, fresh hormone being added after the first phase. (N alpha-(4-Azidophenylacetyl-serine1)-alpha-MSH (I), (2'-(2-nitro-4-azidophenylsulphenyl)-tryptophan/sub 9/)-alpha-MSH (II) and (p-azidophenylalanine/sub 13/)-alpha-MSH (III) all inserted into the receptor to about the same extent, as judged from the persistence of the longlasting signal. In contrast, (D-alanine1, p-azidophenylalanin2/sub 2/, norvaline/sub 4/)-alpha-MSH (IV) and (N alpha-(4-azidophenylacetyl)-serine1, leucine/sub 9/)-alpha-MSH (V) gave much less insertion and (leucine/sub 9/, p-azidophenylalanine/sub 13/)-alpha-MSH (VI) hardly any insertion when applied in the same relative excess (5-fold the concentration inducing a maximal response). Covalent attachment of the cleavable photolabel (N alpha-(4-azidophenyl)-1, 3'-dithio-propionyl-serine1)-alpha-MSH (VII) and subsequent washing of the skin in buffer containing 1% beta-mercaptoethanol released the peptide from the receptor. Insertion of the C-terminal photolabel (p-azidophenylalanine/sub 13/)-alpha-MSH was reduced by the weak antagonist H-Phe-Ala-Trp-Gly-Gly-Pro-Val-NH/sub 2/. These experiments prove that hormone receptors can be covalently labelled in tissue with very limited light transparency.

  12. Palmitoylation of caveolin-1 in endothelial cells is post-translational but irreversible

    NASA Technical Reports Server (NTRS)

    Parat, M. O.; Fox, P. L.

    2001-01-01

    Caveolin-1 is a palmitoylated protein involved in assembly of signaling molecules in plasma membrane subdomains termed caveolae and in intracellular cholesterol transport. Three cysteine residues in the C terminus of caveolin-1 are subject to palmitoylation, which is not necessary for caveolar targeting of caveolin-1. Protein palmitoylation is a post-translational and reversible modification that may be regulated and that in turn may regulate conformation, membrane association, protein-protein interactions, and intracellular localization of the target protein. We have undertaken a detailed analysis of [(3)H]palmitate incorporation into caveolin-1 in aortic endothelial cells. The linkage of palmitate to caveolin-1 was hydroxylamine-sensitive and thus presumably a thioester bond. However, contrary to expectations, palmitate incorporation was blocked completely by the protein synthesis inhibitors cycloheximide and puromycin. In parallel experiments to show specificity, palmitoylation of aortic endothelial cell-specific nitric-oxide synthase was unaffected by these reagents. Inhibitors of protein trafficking, brefeldin A and monensin, blocked caveolin-1 palmitoylation, indicating that the modification was not cotranslational but rather required caveolin-1 transport from the endoplasmic reticulum and Golgi to the plasma membrane. In addition, immunophilin chaperones that form complexes with caveolin-1, i.e. FK506-binding protein 52, cyclophilin A, and cyclophilin 40, were not necessary for caveolin-1 palmitoylation because agents that bind immunophilins did not inhibit palmitoylation. Pulse-chase experiments showed that caveolin-1 palmitoylation is essentially irreversible because the release of [(3)H]palmitate was not significant even after 24 h. These results show that [(3)H]palmitate incorporation is limited to newly synthesized caveolin-1, not because incorporation only occurs during synthesis but because the continuous presence of palmitate on caveolin-1 prevents

  13. Why irreversibility? The formulation of classical and quantum mechanics for nonintegrable systems

    SciTech Connect

    Prigogine, I.

    1995-01-05

    Nonintegrable Poincare systems with a continuous spectrum lead to the appearance of diffusive terms in the frame of classical or quantum dynamics. These terms break time symmetry. They lead, therefore, to limitations to classical trajectory theory and of wave-function formalism. These diffusive terms correspond to well-defined classes of dynamical processes. The diffusive effects are amplified in situations corresponding to persistent interactions. As a result, we have to include, already, in the fundamental dynamical description the two basic aspects, probability and irreversibility, which are so conspicuous on the macroscopic level. We have to formulate both classical and quantum mechanics on the Liouville level of probability distributions. For integrable systems, we recover the usual formulation of classical or quantum mechanics. Instead of being primitive concepts, which cannot be further analyzed, trajectories and wave functions appear as special solutions of the Liouville-von Neumann equations. This extension of classical and quantum dynamics permits us to unify the two concepts of nature that we inherited from the nineteenth century, based, on the one hand, on dynamical time-reversible laws and, on the other, on an evolutionary view associated to entropy. It leads also to a unified formulation of quantum theory, avoiding the conventional dual structure based on Schroedinger`s equation, on the one hand, and on the {open_quotes}collapse{close_quotes} of the wave function, on the other. A dynamical interpretation is given to processes such as decoherence or approach to equilibrium without any appeal to extra dynamic considerations. There is a striking parallelism between classical and quantum theory. For large Poincare systems (LPS), we have, in general, both a {open_quotes}collapse{close_quotes} of trajectories and of wave functions. In both cases, we need a generalized formulation of dynamics in terms of probability distributions or density matrices.

  14. The Effects of Metallic Implants on Electroporation Therapies: Feasibility of Irreversible Electroporation for Brachytherapy Salvage

    SciTech Connect

    Neal, Robert E.; Smith, Ryan L.; Kavnoudias, Helen; Rosenfeldt, Franklin Ou, Ruchong; Mclean, Catriona A.; Davalos, Rafael V.; Thomson, Kenneth R.

    2013-12-15

    Purpose: Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. Materials and Methods: This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. Results: There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. Conclusion: This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.

  15. Pain Analysis in Patients with Hepatocellular Carcinoma: Irreversible Electroporation versus Radiofrequency Ablation-Initial Observations

    SciTech Connect

    Narayanan, Govindarajan Froud, Tatiana; Lo, Kaming; Barbery, Katuska J. Perez-Rojas, Evelyn Yrizarry, Jose

    2013-02-15

    To retrospectively compare the postprocedure pain of hepatocellular carcinoma treated with irreversible electroporation (IRE) with radiofrequency ablation (RFA). This Health Insurance Portability and Accountability Act-compliant, institutional review board-approved study compared postprocedure pain in 21 patients (15 men, six women; mean age 61.5 years) who underwent IRE of 29 intrahepatic lesions (mean size 2.20 cm) in 28 IRE sessions with 22 patients (16 men, six women; mean age 60.2 years) who underwent RFA of 27 lesions (mean size 3.38 cm) in 25 RFA sessions. Pain was determined by patient-disclosed scores with an 11-point numerical rating scale and 24 h cumulative hydromorphone use from patient-controlled analgesia pump. Complications were noted. Statistical significance was evaluated by Fisher's exact test, the Chi-square test, and Student's t test. There was no significant difference in the cumulative hydromorphone dose (1.54 mg (IRE) vs. 1.24 mg (RFA); P = 0.52) and in the mean pain score (1.96 (IRE) vs. 2.25 (RFA); P = 0.70). In nine (32.14 %) of 28 IRE sessions and 11 (44.0 %) of 25 RFA sessions, patients reported no pain. Complications occurred in three (10.7 %) of 28 IRE treatments and included pneumothorax (n = 1), pleural effusion (n = 1), and bleeding in the form of hemothorax (n = 1); one (4 %) of 25 RFA treatments included burn. IRE is comparable to RFA in the amount of pain that patients experience and the amount of pain medication self-administered. Both modalities were well tolerated by patients. Prospective, randomized trials are necessary to further evaluate these findings.

  16. Irreversible prey diapause as an optimal strategy of a physiologically extended Lotka-Volterra model.

    PubMed

    Staňková, Kateřina; Abate, Alessandro; Sabelis, Maurice W

    2013-03-01

    We propose an optimal control framework to describe intra-seasonal predator-prey interactions, which are characterized by a continuous-time dynamical model comprising predator and prey density, as well as the energy budget of the prey over the length of a season. The model includes a time-dependent decision variable for the prey, representing the portion of the prey population in time that is active, as opposed to diapausing (a state of physiological rest). The predator follows autonomous dynamics and accordingly it remains active during the season. The proposed model is a generalization of the classical Lotka-Volterra predator-prey model towards non-autonomous dynamics that furthermore includes the effect of an energy variable. The model has been inspired by a specific biological system of predatory mites (Acari: Phytoseiidae) and prey mites (so-called fruit-tree red spider mites) (Acari: Tetranychidae) that feed on leaves of apple trees--its parameters have been instantiated based on laboratory and field studies. The goal of the work is to understand the decisions of the prey mites to enter diapause (a state of physiological rest) given the dynamics of the predatory mites: this is achieved by solving an optimization problem hinging on the maximization of the prey population contribution to the next season. The main features of the optimal strategy for the prey are shown to be that (1) once in diapause, the prey does not become active again within the same season and hence diapause is an irreversible process; (2) for the vast majority of parameter space, the portion of prey individuals entering diapause within the season does not decrease in time; (3) with an increased number of predators, the optimal population strategy for the prey is to start diapause earlier and to enter diapause more gradually. This optimal population strategy will be studied for its ESS properties in a sequel to the work presented in this article.

  17. A statistical model describing combined irreversible electroporation and electroporation-induced blood-brain barrier disruption

    PubMed Central

    Sharabi, Shirley; Kos, Bor; Last, David; Guez, David; Daniels, Dianne; Harnof, Sagi; Miklavcic, Damijan

    2016-01-01

    Background Electroporation-based therapies such as electrochemotherapy (ECT) and irreversible electroporation (IRE) are emerging as promising tools for treatment of tumors. When applied to the brain, electroporation can also induce transient blood-brain-barrier (BBB) disruption in volumes extending beyond IRE, thus enabling efficient drug penetration. The main objective of this study was to develop a statistical model predicting cell death and BBB disruption induced by electroporation. This model can be used for individual treatment planning. Material and methods Cell death and BBB disruption models were developed based on the Peleg-Fermi model in combination with numerical models of the electric field. The model calculates the electric field thresholds for cell kill and BBB disruption and describes the dependence on the number of treatment pulses. The model was validated using in vivo experimental data consisting of rats brains MRIs post electroporation treatments. Results Linear regression analysis confirmed that the model described the IRE and BBB disruption volumes as a function of treatment pulses number (r2 = 0.79; p < 0.008, r2 = 0.91; p < 0.001). The results presented a strong plateau effect as the pulse number increased. The ratio between complete cell death and no cell death thresholds was relatively narrow (between 0.88-0.91) even for small numbers of pulses and depended weakly on the number of pulses. For BBB disruption, the ratio increased with the number of pulses. BBB disruption radii were on average 67% ± 11% larger than IRE volumes. Conclusions The statistical model can be used to describe the dependence of treatment-effects on the number of pulses independent of the experimental setup. PMID:27069447

  18. Short- and Mid-term Effects of Irreversible Electroporation on Normal Renal Tissue: An Animal Model

    SciTech Connect

    Wendler, J. J. Porsch, M.; Huehne, S.; Baumunk, D.; Buhtz, P.; Fischbach, F.; Pech, M.; Mahnkopf, D.; Kropf, S.; Roessner, A.; Ricke, J.; Schostak, M.; Liehr, U.-B.

    2013-04-15

    Irreversible electroporation (IRE) is a novel nonthermal tissue ablation technique by high current application leading to apoptosis without affecting extracellular matrix. Previous results of renal IRE shall be supplemented by functional MRI and differentiated histological analysis of renal parenchyma in a chronic treatment setting. Three swine were treated with two to three multifocal percutaneous IRE of the right kidney. MRI was performed before, 30 min (immediate-term), 7 days (short-term), and 28 days (mid-term) after IRE. A statistical analysis of the lesion surrounded renal parenchyma intensities was made to analyze functional differences depending on renal part, side and posttreatment time. Histological follow-up of cortex and medulla was performed after 28 days. A total of eight ablations were created. MRI showed no collateral damage of surrounded tissue. The highest visual contrast between lesions and normal parenchyma was obtained by T2-HR-SPIR-TSE-w sequence of DCE-MRI. Ablation zones showed inhomogeneous necroses with small perifocal edema in the short-term and sharp delimitable scars in the mid-term. MRI showed no significant differences between adjoined renal parenchyma around ablations and parenchyma of untreated kidney. Histological analysis demonstrated complete destruction of cortical glomeruli and tubules, while collecting ducts, renal calyxes, and pelvis of medulla were preserved. Adjoined kidney parenchyma around IRE lesions showed no qualitative differences to normal parenchyma of untreated kidney. This porcine IRE study reveals a multifocal renal ablation, while protecting surrounded renal parenchyma and collecting system over a mid-term period. That offers prevention of renal function ablating centrally located or multifocal renal masses.

  19. Planning Irreversible Electroporation in the Porcine Kidney: Are Numerical Simulations Reliable for Predicting Empiric Ablation Outcomes?

    SciTech Connect

    Wimmer, Thomas Srimathveeravalli, Govindarajan; Gutta, Narendra; Ezell, Paula C.; Monette, Sebastien; Maybody, Majid; Erinjery, Joseph P.; Durack, Jeremy C.; Coleman, Jonathan A.; Solomon, Stephen B.

    2015-02-15

    PurposeNumerical simulations are used for treatment planning in clinical applications of irreversible electroporation (IRE) to determine ablation size and shape. To assess the reliability of simulations for treatment planning, we compared simulation results with empiric outcomes of renal IRE using computed tomography (CT) and histology in an animal model.MethodsThe ablation size and shape for six different IRE parameter sets (70–90 pulses, 2,000–2,700 V, 70–100 µs) for monopolar and bipolar electrodes was simulated using a numerical model. Employing these treatment parameters, 35 CT-guided IRE ablations were created in both kidneys of six pigs and followed up with CT immediately and after 24 h. Histopathology was analyzed from postablation day 1.ResultsAblation zones on CT measured 81 ± 18 % (day 0, p ≤ 0.05) and 115 ± 18 % (day 1, p ≤ 0.09) of the simulated size for monopolar electrodes, and 190 ± 33 % (day 0, p ≤ 0.001) and 234 ± 12 % (day 1, p ≤ 0.0001) for bipolar electrodes. Histopathology indicated smaller ablation zones than simulated (71 ± 41 %, p ≤ 0.047) and measured on CT (47 ± 16 %, p ≤ 0.005) with complete ablation of kidney parenchyma within the central zone and incomplete ablation in the periphery.ConclusionBoth numerical simulations for planning renal IRE and CT measurements may overestimate the size of ablation compared to histology, and ablation effects may be incomplete in the periphery.

  20. Irreversible electroporation of the liver: is there a safe limit to the ablation volume?

    PubMed Central

    Sánchez-Velázquez, P.; Castellví, Q.; Villanueva, A.; Quesada, R.; Pañella, C.; Cáceres, M.; Dorcaratto, D.; Andaluz, A.; Moll, X.; Trujillo, M.; Burdío, J. M.; Berjano, E.; Grande, L.; Ivorra, A.; Burdío, F.

    2016-01-01

    Irreversible electroporation is a fast-growing liver ablation technique. Although safety has been well documented in small ablations, our aim is to assess its safety and feasibility when a large portion of liver is ablated. Eighty-seven mice were subjected to high voltage pulses directly delivered across parallel plate electrodes comprising around 40% of mouse liver. One group consisted in 55 athymic-nude, in which a tumor from the KM12C cell line was grown and the other thirty-two C57-Bl6 non-tumoral mice. Both groups were subsequently divided into subsets according to the delivered field strength (1000 V/cm, 2000 V/cm) and whether or not they received anti-hyperkalemia therapy. Early mortality (less than 24 hours post-IRE) in the 2000 V/cm group was observed and revealed considerably higher mean potassium levels. In contrast, the animals subjected to a 2000 V/cm field treated with the anti-hyperkalemia therapy had higher survival rates (OR = 0.1, 95%CI = 0.02–0.32, p < 0.001). Early mortality also depended on the electric field magnitude of the IRE protocol, as mice given 1000 V/cm survived longer than those given 2000 V/cm (OR = 4.7, 95%CI = 1.8–11.8, p = 0.001). Our findings suggest that ionic disturbances, mainly due to potassium alterations, should be warned and envisioned when large volume ablations are performed by IRE. PMID:27032535

  1. Assuring ultra-clean environments in microsystem packages : irreversible and reversible getters.

    SciTech Connect

    Zifer, Thomas; Whinnery, LeRoy L., Jr.; Hollenshead, Jeromy Todd; Buffleben, George M.; McElhanon, James Ross; Nilson, Robert H.

    2003-11-01

    A new generation of irreversible, chemically reacting getters specifically targeted toward assuring the integrity of the local environment within microsystem packages were developed and evaluated. These reactive getters incorporate volatile species into a polymer through covalent bonds, thus producing a non-volatile product. These reactive getters will be combined with getters that rely on absorption media (e.g. zeolites and high surface area carbon fibers) to scavenge non-reactive species, like solvents. Our getter systems will rely on device packaging to limit exchange between the microsystem and the global environment. Thus, the internal getters need only provide local environmental control within the microsystem package. A series of experiments were conducted to determine uptake rates and capacities absorption and reactive-based getters. Diffusion rates through the binder used to hold the getter particles together were also investigated. Getters were evaluated in environments with a saturated headspace and with a limited amount of the volatile species of interest. One- and two-dimensional numerical models and analysis techniques have been developed and used to predict the transport of contaminant species within a representative microsystem package consisting of an open gas-filled volume adjacent to a polymer layer containing embedded particles of getter. The two-dimensional model features explicit representation of the individual getter particles while the one-dimensional treatment assumes a homogeneous distribution of getter material within the getterlpolymer layer. Example calculations illustrate the dependence of getter performance on reaction rates, polymer diffusivity, and getter particle volume fraction. In addition, the model is used to deduce surface reaction rates, solid phase diffusivities, and maximum-loading densities by least-squares fitting of model predictions to measured histories of gas-phase contaminant concentration and getter weight gain.

  2. Improved Local and Systemic Anti-Tumor Efficacy for Irreversible Electroporation in Immunocompetent versus Immunodeficient Mice

    PubMed Central

    Neal, Robert E.; Rossmeisl, John H.; Robertson, John L.; Arena, Christopher B.; Davis, Erica M.; Singh, Ravi N.; Stallings, Jonathan; Davalos, Rafael V.

    2013-01-01

    Irreversible electroporation (IRE) is a non-thermal focal ablation technique that uses a series of brief but intense electric pulses delivered into a targeted region of tissue, killing the cells by irrecoverably disrupting cellular membrane integrity. This study investigates if there is an improved local anti-tumor response in immunocompetent (IC) BALB/c versus immunodeficient (ID) nude mice, including the potential for a systemic protective effect against rechallenge. Subcutaneous murine renal carcinoma tumors were treated with an IRE pulsing protocol that used 60% of the predicted voltage required to invoke complete regressions in the ID mice. Tumors were followed for 34 days following treatment for 11 treated mice from each strain, and 7 controls from each strain. Mouse survival based on tumor burden and the progression-free disease period was substantially longer in the treated IC mice relative to the treated ID mice and sham controls for both strains. Treated IC mice were rechallenged with the same cell line 18 days after treatment, where growth of the second tumors was shown to be significantly reduced or prevented entirely. There was robust CD3+ cell infiltration in some treated BALB/C mice, with immunocytes focused at the transition between viable and dead tumor. There was no difference in the low immunocyte presence for untreated tumors, nude mice, and matrigel-only injections in both strains. These findings suggest IRE therapy may have greater therapeutic efficacy in immunocompetent patients than what has been suggested by immunodeficient models, and that IRE may invoke a systemic response beyond the targeted ablation region. PMID:23717630

  3. Liver Function Tests Following Irreversible Electroporation of Liver Tumors: Experience in 174 Procedures.

    PubMed

    Froud, Tatiana; Venkat, Shree R; Barbery, Katuzka J; Gunjan, Arora; Narayanan, Govindarajan

    2015-09-01

    Irreversible electroporation (IRE) is a relatively new ablation modality that uses electric currents to cause cell death. It is commonly used to treat primary and secondary liver tumors in patients with normal liver function and preexisting cirrhosis. Retrospective analysis of 205 procedures sought to evaluate changes in liver function after IRE. Liver function tests (LFTs) results before and after IRE were evaluated from 174 procedures in 124 patients. Aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase (ALKP), and total bilirubin levels were analyzed. The study was Health Insurance Portability and Accountability Act compliant and institutional review board approved. Informed consent was waived. Changes in LFT results after IRE were compared with baseline and were followed up over time to see if they resolved. Changes were compared with volume of ablation. The greatest perturbations were in transaminase levels. The levels increased sharply within 24 hours after IRE in 129 (74.1%) procedures to extreme levels (more than 20 times the upper limit of normal in one-third of cases). Resolution occurred in 95% and was demonstrated to have occurred by a mean of approximately 10 weeks, many documented as early as 7 days after procedure. ALKP levels elevated in 10% procedures, was slower to increase, and was less likely to resolve. Total bilirubin level demonstrated 2 different patterns of elevation--early and late--and similar to ALKP, it was more likely to remain elevated. There was no increased risk in patients with cirrhosis or cholangiocarcinoma. There was no correlation of levels with volume of ablation. IRE results in significant abnormalities in LFT results, but in most of the cases, these are self-limiting, do not preclude treatment, and are similar to the changes seen after radiofrequency and cryoablation in the liver. PMID:26365543

  4. Assessment of Chronological Effects of Irreversible Electroporation on Hilar Bile Ducts in a Porcine Model

    SciTech Connect

    Choi, Jae Woong Lu, David S. K. Osuagwu, Ferdnand Raman, Steven; Lassman, Charles

    2013-11-07

    PurposeTo evaluate the chronological effects of irreversible electroporation (IRE) on large hilar bile ducts in an in vivo porcine model correlated with computed tomography (CT) cholangiography and histopathology.Materials and MethodsTwelve IRE zones were made along hilar bile ducts intraoperatively under ultrasound (US)-guidance in 11 pigs. Paired electrodes were placed either on opposing sides of the bile duct (straddle [STR]) or both on one side of the bile duct (one-sided [OSD]). The shortest electrode-to-duct distance was classified as periductal (≤2 mm) or nonperiductal (>2 mm). CT cholangiography and laboratory tests were performed before IRE and again at 2 days, 4 weeks, and 8 weeks after IRE. Degree of bile duct injury were graded as follows: grade 0 = no narrowing; grade 1 = ≤50 % duct narrowing; grade 2 = >50 % narrowing without proximal duct dilatation; grade 3 = grade 2 with proximal duct dilatation; and grade 4 = grade 3 with enzyme elevation. Pigs were selected for killing and histopathology at 2 days, 4, and 8 weeks.ResultsNonperiductal electrode placement produced no long-term strictures in 5 of 5 ducts. Periductal electrode placement produced mild narrowing in 6 of 7 ducts: 5 grade 1 and 1 grade 2. None showed increased enzymes. There was no significant difference between STR versus OSD electrode placement. Histopathology showed minor but relatively greater ductal mural changes in narrowed ducts.ConclusionIn the larger hilar ducts, long-term patency and mural integrity appear resistant to IRE damage with the energy deposition used, especially if the electrode is not immediately periductal in position.

  5. Mesenchymal stem cells with irreversibly arrested proliferation stimulate decidua development in rats

    PubMed Central

    Domnina, Alisa P.; Novikova, Polina V.; Lyublinskaya, Olga G.; Zenin, Valeriy V.; Fridlyanskaya, Irina I.; Mikhailov, Vyacheslav M.; Nikolsky, Nikolay N.

    2016-01-01

    Stem cell transplantation, which is based on the application of mesenchymal stem/stromal cells (MSCs), is a rapidly developing approach to the regenerative therapy of various degenerative disorders characterized by brain and heart failure, as well as skin lesions. In comparison, the use of stem cell transplantations to treat infertility has received less attention. One of the causes of miscarriages and fetal growth delay is the loss of the decidual reaction of endometrial cells. The present study modeled decidualization processes in pseudopregnant rats. For cell transplantation experiments, the rats were transplanted with MSCs established from endometrial fragments in menstrual blood (eMSCs). These cells express common MSC markers, are multipotent and are able to differentiate into various tissue lineages. Cell therapy frequently requires substantial cell biomass, and cultivation of MSCs may be accompanied by significant changes to their properties, including malignant transformation. In order to minimize the potential for malignant transformation, the proliferation of eMSCs was irreversibly suppressed by irradiation and mitomycin C treatment. Transplantation of the rats with viable, non-proliferating eMSCs stimulated the development of all elements of decidual tissue. Conversely, transplantation of the rats with cells killed using 95% ethanol did not result in the development of decidual tissue. The present study demonstrated the potential for applying eMSCs to the cellular therapy of infertility associated with endometrial disorders characterized by decidualization insufficiency and implantation failure. In addition, the transplantation of viable but non-proliferating cells ensured that their oncogenic potential was limited. PMID:27698746

  6. Risk Factors Associated with Irreversible Airway Obstruction in Asthma: A Systematic Review and Meta-Analysis

    PubMed Central

    Zhang, Lanlan; He, Lixiu; Gong, Jin; Liu, Chuntao

    2016-01-01

    Irreversible airway obstruction (IAO) is a subtype of asthma and relates to poorer prognosis in some asthma patients. However, the prevalence and risk factors for IAO are unknown. A systematic review regarding controlled clinical studies (cohort, case-control studies) on IAO asthma in adult and/or children affected by asthma/early wheeze was performed. Eighteen papers were identified in this study. It was reported that the incidence of IAO at random effects or fixed effects in severe asthma and nonsevere asthma was 0.54 (95% CI: 0.45–0.62) and 0.16 (95% CI: 0.12–0.20), respectively. In IAO asthma, the pooled odds ratio (OR) related to smoking exposure was 2.22 (95% CI: 1.82–2.73), the OR for male, smoking, and fractional exhaled nitric oxide (FENO) was 2.22 (95% CI: 1.82–2.7), 1.79 (95% CI: 1.46–2.19), and 2.16 (95% CI: 1.05–4.43), respectively, suggesting these factors increase the risk of IAO. However, a decreased OR in IAO asthma was observed due to rhinitis (OR = 0.31, 95% CI: 0.24–0.40), atopy (OR = 0.584, 95% CI: 0.466–0.732), and atopic dermatitis (OR = 0.60, 95% CI: 0.42–0.85), indicating these factors are associated with reduced risk of IAO. IAO in asthma is associated with gender, smoking, FENO, rhinitis, atopy, and atopic dermatitis. PMID:27119087

  7. First-order irreversible thermodynamic approach to a simple energy converter

    NASA Astrophysics Data System (ADS)

    Arias-Hernandez, L. A.; Angulo-Brown, F.; Paez-Hernandez, R. T.

    2008-01-01

    Several authors have shown that dissipative thermal cycle models based on finite-time thermodynamics exhibit loop-shaped curves of power output versus efficiency, such as it occurs with actual dissipative thermal engines. Within the context of first-order irreversible thermodynamics (FOIT), in this work we show that for an energy converter consisting of two coupled fluxes it is also possible to find loop-shaped curves of both power output and the so-called ecological function versus efficiency. In a previous work Stucki [J. W. Stucki, Eur. J. Biochem. 109, 269 (1980)] used a FOIT approach to describe the modes of thermodynamic performance of oxidative phosphorylation involved in adenosine triphosphate (ATP) synthesis within mithochondrias. In that work the author did not use the mentioned loop-shaped curves and he proposed that oxidative phosphorylation operates in a steady state at both minimum entropy production and maximum efficiency simultaneously, by means of a conductance matching condition between extreme states of zero and infinite conductances, respectively. In the present work we show that all Stucki’s results about the oxidative phosphorylation energetics can be obtained without the so-called conductance matching condition. On the other hand, we also show that the minimum entropy production state implies both null power output and efficiency and therefore this state is not fulfilled by the oxidative phosphorylation performance. Our results suggest that actual efficiency values of oxidative phosphorylation performance are better described by a mode of operation consisting of the simultaneous maximization of both the so-called ecological function and the efficiency.

  8. A Major Role for Side-Chain Polyglutamine Hydrogen Bonding in Irreversible Ataxin-3 Aggregation

    PubMed Central

    Relini, Annalisa; Apicella, Alessandra; Invernizzi, Gaetano; Casari, Carlo; Gliozzi, Alessandra; Doglia, Silvia Maria; Tortora, Paolo; Regonesi, Maria Elena

    2011-01-01

    The protein ataxin-3 consists of an N-terminal globular Josephin domain (JD) and an unstructured C-terminal region containing a stretch of consecutive glutamines that triggers the neurodegenerative disorder spinocerebellar ataxia type 3, when it is expanded beyond a critical threshold. The disease results from misfolding and aggregation, although the pathway and structure of the aggregation intermediates are not fully understood. In order to provide insight into the mechanism of the process, we monitored the aggregation of a normal (AT3Q24) ataxin-3, an expanded (AT3Q55) ataxin-3, and the JD in isolation. We observed that all of them aggregated, although the latter did so at a much slower rate. Furthermore, the expanded AT3Q55 displayed a substantially different behavior with respect to the two other variants in that at the latest stages of the process it was the only one that did the following: i) lost its reactivity towards an anti-oligomer antibody, ii) generated SDS-insoluble aggregates, iii) gave rise to bundles of elongated fibrils, and iv) displayed two additional bands at 1604 and 1656 cm−1 in FTIR spectroscopy. Although these were previously observed in other aggregated polyglutamine proteins, no one has assigned them unambiguously, yet. By H/D exchange experiments we show for the first time that they can be ascribed to glutamine side-chain hydrogen bonding, which is therefore the hallmark of irreversibly SDS-insoluble aggregated protein. FTIR spectra also showed that main-chain intermolecular hydrogen bonding preceded that of glutamine side-chains, which suggests that the former favors the latter by reorganizing backbone geometry. PMID:21533208

  9. Heat-induced Irreversible Denaturation of the Camelid Single Domain VHH Antibody Is Governed by Chemical Modifications

    PubMed Central

    Akazawa-Ogawa, Yoko; Takashima, Mizuki; Lee, Young-Ho; Ikegami, Takahisa; Goto, Yuji; Uegaki, Koichi; Hagihara, Yoshihisa

    2014-01-01

    The variable domain of camelid heavy chain antibody (VHH) is highly heat-resistant and is therefore ideal for many applications. Although understanding the process of heat-induced irreversible denaturation is essential to improve the efficacy of VHH, its inactivation mechanism remains unclear. Here, we showed that chemical modifications predominantly governed the irreversible denaturation of VHH at high temperatures. After heat treatment, the activity of VHH was dependent only on the incubation time at 90 °C and was insensitive to the number of heating (90 °C)-cooling (20 °C) cycles, indicating a negligible role for folding/unfolding intermediates on permanent denaturation. The residual activity was independent of concentration; therefore, VHH lost its activity in a unimolecular manner, not by aggregation. A VHH mutant lacking Asn, which is susceptible to chemical modifications, had significantly higher heat resistance than did the wild-type protein, indicating the importance of chemical modifications to VHH denaturation. PMID:24739391

  10. Temperature-dependent reversible and irreversible processes in Nb-doped PbZrO3 relaxor ferroelectric thin films

    NASA Astrophysics Data System (ADS)

    Ye, Mao; Huang, Haitao; Li, Tao; Ke, Shanming; Lin, Peng; Peng, Biaolin; Mai, Manfang; Sun, Qiu; Peng, Xiang; Zeng, Xierong

    2015-11-01

    The dielectric and ferroelectric nonlinearity of Nb-doped PbZrO3 relaxor ferroelectric thin films was investigated. The ac field dependence of the permittivity of relaxor ferroelectric thin films is demonstrated to be described by a Rayleigh type relation. Both reversible and irreversible components of dielectric permittivity decrease linearly with the logarithm of the frequency of the ac field. The irreversible Rayleigh coefficient α'(T) shows a peak around the "freezing temperature" Tf, which is probably according to the transition from polar nano-regions (PNRs) to dipole-glass state in relaxor ferroelectrics. The results demonstrate that the models describing the interaction of domain walls and randomly distributed pinning centers in ferroelectric materials can be extended to the displacement of nanoscale walls in relaxors.

  11. On reversible, endoreversible, and irreversible heat device cycles versus the Carnot cycle: a pedagogical approach to account for losses

    NASA Astrophysics Data System (ADS)

    Gonzalez-Ayala, J.; Angulo-Brown, F.; Calvo Hernández, A.; Velasco, S.

    2016-07-01

    In this work we analyze the deviations of reversible cycles (for both heat engines and refrigerators) from the corresponding Carnot cycle operating between the same extreme temperatures, and deviations of irreversible cycles from their corresponding reversible realization while putting emphasis on the corresponding losses. The endoreversible models fit in the proposed framework. Two suitable loss factors, which do not need the explicit calculation of entropy variations, are introduced. The behavior of these factors and their interplay allow for a clear and pedagogical visualization of where external and internal irreversibilities are located, and their intensities in terms of the main variables describing the cycle. The analysis could be used as a starting point for more advanced studies on modeling and optimization of real devices and installations.

  12. Study and characterization of the irreversible transformation of electrically stressed planar Ti/TiO{sub x}/Ti junctions

    SciTech Connect

    Guillaume, N.; Puyoo, E. Le Berre, M.; Albertini, D.; Baboux, N.; Chevalier, C.; Ayadi, K.; Grégoire, J.; Gautier, B.; Calmon, F.

    2015-10-14

    We investigate the properties and characteristics of planar Ti/TiO{sub x}/Ti junctions, which consist of transverse TiO{sub x} lines drawn on Ti test patterns. Junctions are elaborated by means of local anodic oxidation using atomic force microscopy. An irreversible morphological transformation occurring in a reproducible manner is observed when these planar junctions are electrically stressed under ambient atmosphere. Structural and chemical analyses based on transmission electron microscopy techniques reveal the extension of the initial amorphous TiO{sub x} into a crystalline rutile phase. This irreversible transformation is proven to vanish completely if the electrical stress occurs under vacuum atmosphere. Finally, we carry out temperature dependent electrical measurements in order to elucidate their conduction mechanism: Schottky emission above an ultra-low potential barrier is assumed to dominate under vacuum atmosphere whereas ionic conduction seems to prevail in air.

  13. Irreversible evolution of angular-dependent coercivity in Fe80Ni20 nanowire arrays: Detection of a single vortex state

    NASA Astrophysics Data System (ADS)

    Alikhani, M.; Ramazani, A.; Almasi Kashi, M.; Samanifar, S.; Montazer, A. H.

    2016-09-01

    The irreversible evolution of magnetic coercivity in arrays of 75 nm diameter Fe80Ni20 nanowires (NWs) has been explored by means of first-order reversal curve (FORC) analysis as a function of the angle between the magnetic field and the NW axis (0°≤θ≤90°). The Fe80Ni20 NWs with lengths up to 60 μm were fabricated using a pulsed electrodeposition method into hard-anodic aluminum oxide templates with an interpore distance of 275 nm. Investigating the interwire and intrawire magnetostatic interactions, the angular FORC (AFORC) diagrams indicated enhanced intrawire interactions with increasing length and θ (<90°), induced by a magnetization reversal through vortex domain wall (VDW) propagation. Intriguingly, in addition to the VDW mode, a single vortex state with broad irreversible switching of nucleation and annihilation fields was detected at θ=83° for 60 μm long NWs. At θ=90°, the NWs reversed magnetization through transverse domain wall, involving a reversible component by a fraction of 95%. Furthermore, the transition angle between the reversal modes was found to decrease with increasing aspect ratio from 200 to 800. The irreversible angular-dependent coercivity (HcIrrev(θ)) of Fe80Ni20 NWs was extracted from the AFORC measurements and compared with the major angular dependence of coercivity (HcMajor(θ)) obtained from the conventional hysteresis loop measurements. While HcMajor(θ) showed a non-monotonic behavior, HcIrrev(θ) constantly increased with increasing θ (<90°). On the other hand, using analytical models, a 93% agreement was obtained between the theoretical angular-dependent nucleation field and experimental HcIrrev(θ) for irreversible switching of VDW when 0°≤θ≤86°.

  14. Interannual Variability of Ozone in the Winter Lower Stratosphere and the Relationship to Lamina and Irreversible Transport

    NASA Technical Reports Server (NTRS)

    Olsen, Mark A.; Douglass, Anne R.; Schoeberl, Mark R.; Rodriquez, Jose M.; Yoshida, Yasuko

    2010-01-01

    We use the high-resolution dynamic limb sounder (HIRDLS) high-vertical resolution ozone profiles in the northern hemisphere lower stratosphere to examine the meridional transport out of the tropics. We focus on February 2005.2007 when there are differences in the dynamical background in the lower stratosphere due to the states of the quasibiennial oscillation and polar vortex. HIRDLS data reveal a large number of low ozone laminae that have the characteristics of tropical air at midlatitudes. More laminae are observed in February in 2006 than in 2005 or 2007. Because laminae can form, move out of the tropics, and return to the tropics without mixing into the midlatitude ozone field, the number of laminae is not directly related to the net transport. We use equivalent latitude coordinates to discriminate between reversible and irreversible laminar transport. The equivalent latitude analysis shows greater irreversible transport between the tropics and lower midlatitudes in both 2005 and 2007 compared to 2006 despite the higher number of laminae observed in 2006. Our conclusion that there was more irreversible transport of tropical air into the lower midlatitudes in 2005 and 2007 is supported by equivalent length analysis of mixing using microwave limb sounder N2O measurements. This study shows that reversibility must be considered in order to infer the importance of lamination to net transport.

  15. Effect of temperature on extracellular organic matter (EOM) of Chlorella pyrenoidosa and effect of EOM on irreversible membrane fouling.

    PubMed

    Zhao, Fangchao; Su, Yiming; Tan, Xiaobo; Chu, Huaqiang; Zhang, Yalei; Yang, Libin; Zhou, Xuefei

    2015-12-01

    Extracellular organic matter (EOM) can cause serious membrane fouling during the algae harvesting process. In this study, the secretion of EOM, including bound-EOM (bEOM) and dissolved-EOM (dEOM), by Chlorella pyrenoidosa (C. pyrenoidosa) at different culturing temperatures, and their influences on membrane filtration, have been investigated. The secretion of EOM was markedly reduced at high temperatures. The specific EOM secretion rate (SEOM) reached 831.1 ± 55.3mg/g at the lowest temperatures of 15 °C; in contrast, the SEOM decreased to only 370-442 and 356-406 mg/g with temperature rising above 20-25 and 30-35 °C, respectively. Based on membrane filtration experiments, the influence of EOM on irreversible membrane fouling was studied. In a critical flux experiment, low critical flux (24 L/m(2)h) was observed in a system with a high EOM concentration. The fouled membranes were rinsed by water and then used for continuous filtration, scanning electron microscope (SEM) analysis and fourier transform infrared spectroscopy (FTIR) analysis. The results revealed that there was irreversible membrane fouling caused by EOM, and irreversible membrane fouling can be more serious when an algae solution contains high EOM levels.

  16. Irreversible inhibition of RANK expression as a possible mechanism for IL-3 inhibition of RANKL-induced osteoclastogenesis

    SciTech Connect

    Khapli, Shruti M.; Tomar, Geetanjali B.; Barhanpurkar, Amruta P.; Gupta, Navita; Yogesha, S.D.; Pote, Satish T.; Wani, Mohan R.

    2010-09-03

    Research highlights: {yields} IL-3 inhibits receptor activator of NF-{kappa}B ligand (RANKL)-induced osteoclastogenesis. {yields} IL-3 inhibits RANKL-induced JNK activation. {yields} IL-3 down-regulates expression of c-Fos and NFATc1 transcription factors. {yields} IL-3 down-regulates RANK expression posttranscriptionally and irreversibly. {yields} IL-3 inhibits in vivo RANK expression. -- Abstract: IL-3, a cytokine secreted by activated T lymphocytes, stimulates the proliferation, differentiation and survival of pluripotent hematopoietic stem cells. In this study, we investigated the mechanism of inhibitory action of IL-3 on osteoclast differentiation. We show here that IL-3 significantly inhibits receptor activator of NF-{kappa}B (RANK) ligand (RANKL)-induced activation of c-Jun N-terminal kinase (JNK). IL-3 down-regulates expression of c-Fos and nuclear factor of activated T cells (NFATc1) transcription factors. In addition, IL-3 down-regulates RANK expression posttranscriptionally in both purified osteoclast precursors and whole bone marrow cells. Furthermore, the inhibitory effect of IL-3 on RANK expression was irreversible. Interestingly, IL-3 inhibits in vivo RANK expression in mice. Thus, we provide the first evidence that IL-3 irreversibly inhibits RANK expression that results in inhibition of important signaling molecules induced by RANKL.

  17. Reversible and Irreversible Responses of Defect-Engineered Graphene-Based Electrolyte-Gated pH Sensors.

    PubMed

    Kwon, Sun Sang; Yi, Jaeseok; Lee, Won Woo; Shin, Jae Hyeok; Kim, Su Han; Cho, Seunghee H; Nam, SungWoo; Park, Won Il

    2016-01-13

    We have studied the role of defects in electrolyte-gated graphene mesh (GM) field-effect transistors (FETs) by introducing engineered edge defects in graphene (Gr) channels. Compared with Gr-FETs, GM-FETs were characterized as having large increments of Dirac point shift (∼30-100 mV/pH) that even sometimes exceeded the Nernst limit (59 mV/pH) by means of electrostatic gating of H(+) ions. This feature was attributed to the defect-mediated chemisorptions of H(+) ions to the graphene edge, as supported by Raman measurements and observed cycling characteristics of the GM FETs. Although the H(+) ion binding to the defects increased the device response to pH change, this binding was found to be irreversible. However, the irreversible component showed relatively fast decay, almost disappearing after 5 cycles of exposure to solutions of decreasing pH value from 8.25 to 6.55. Similar behavior could be found in the Gr-FET, but the irreversible component of the response was much smaller. Finally, after complete passivation of the defects, both Gr-FETs and GM-FETs exhibited only reversible response to pH change, with similar magnitude in the range of 6-8 mV/pH. PMID:26692009

  18. Comparison of ablation defect on MR imaging with computer simulation estimated treatment zone following irreversible electroporation of patient prostate.

    PubMed

    Srimathveeravalli, Govindarajan; Cornelis, Francois; Mashni, Joseph; Takaki, Haruyuki; Durack, Jeremy C; Solomon, Stephen B; Coleman, Jonathan A

    2016-01-01

    To determine whether patient specific numerical simulations of irreversible electroporation (IRE) of the prostate correlates with the treatment effect seen on follow-up MR imaging. Computer models were created using intra-operative US images, post-treatment follow-up MR images and clinical data from six patients receiving IRE. Isoelectric contours drawn using simulation results were compared with MR imaging to estimate the energy threshold separating treated and untreated tissue. Simulation estimates of injury to the neurovascular bundle and rectum were compared with clinical follow-up and patient reported outcomes. At the electric field strength of 700 V/cm, simulation estimated electric field distribution was not different from the ablation defect seen on follow-up MR imaging (p = 0.43). Simulation predicted cross sectional area of treatment (mean 532.33 ± 142.32 mm(2)) corresponded well with the treatment zone seen on MR imaging (mean 540.16 ± 237.13 mm(2)). Simulation results did not suggest injury to the rectum or neurovascular bundle, matching clinical follow-up at 3 months. Computer simulation estimated zone of irreversible electroporation in the prostate at 700 V/cm was comparable to measurements made on follow-up MR imaging. Numerical simulation may aid treatment planning for irreversible electroporation of the prostate in patients.

  19. Long lasting MDM2/Translocator protein modulator: a new strategy for irreversible apoptosis of human glioblastoma cells

    PubMed Central

    Zappelli, Elisa; Marinelli, Luciana; Novellino, Ettore; Da Settimo, Federico; Taliani, Sabrina; Trincavelli, Maria L.; Martini, Claudia

    2016-01-01

    The development of multi-target drugs and irreversible modulators of deregulated signalling proteins is the major challenge for improving glioblastoma multiforme (GBM) treatment. Reversible single-target drugs are not sufficient to sustain a therapeutic effect over time and may favour the activation of alternative signalling pathways and the onset of resistance phenomena. Thus, a multi-target compound that has a long-lasting mechanism of action might have a greater and longer life span of anti-proliferative activity. Recently, a dual-target indol-3ylglyoxyldipeptide derivative, designed to bind to the Translocator Protein (TSPO) and reactivate p53 function via dissociation from its physiological inhibitor, murine double minute 2 (MDM2), has been developed as a potent GBM pro-apoptotic agent. In this study, this derivative was chemically modified to irreversibly bind MDM2 and TSPO. The new compound elicited a TSPO-mediated mitochondrial membrane dissipation and restored p53 activity, triggering a long-lasting apoptosis of GBM cells. These effects were sustained over time, involved a stable activation of extracellular signal regulated kinases and were specifically observed in cancer cells, in which these protein kinases are deregulated. Dual-targeting and irreversible binding properties combined in the same molecule may represent a useful strategy to overcome the time-limited effects elicited by classical chemotherapies. PMID:26761214

  20. Origin of the irreversibility line in thin YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films with and without columnar defects

    SciTech Connect

    Prozorov, R.; Konczykowski, M.; Schmidt, B.; Yeshurun, Y.; Shaulov, A.; Villard, C.; Koren, G.

    1996-12-01

    We report on measurements of the angular dependence of the irreversibility temperature {ital T}{sub irr}({theta}) in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} thin films, defined by the onset of a third-harmonic signal and measured by a miniature Hall probe. From the functional form of {ital T}{sub irr}({theta}) we conclude that the origin of the irreversibility line in unirradiated films is a dynamic crossover from an unpinned to a pinned vortex liquid. In irradiated films the irreversibility temperature is determined by the trapping angle. {copyright} {ital 1996 The American Physical Society.}

  1. Irreversibility of T-Cell Specification: Insights from Computational Modelling of a Minimal Network Architecture

    PubMed Central

    Manesso, Erica; Kueh, Hao Yuan; Freedman, George; Rothenberg, Ellen V.

    2016-01-01

    Background/Objectives A cascade of gene activations under the control of Notch signalling is required during T-cell specification, when T-cell precursors gradually lose the potential to undertake other fates and become fully committed to the T-cell lineage. We elucidate how the gene/protein dynamics for a core transcriptional module governs this important process by computational means. Methods We first assembled existing knowledge about transcription factors known to be important for T-cell specification to form a minimal core module consisting of TCF-1, GATA-3, BCL11B, and PU.1 aiming at dynamical modeling. Model architecture was based on published experimental measurements of the effects on each factor when each of the others is perturbed. While several studies provided gene expression measurements at different stages of T-cell development, pure time series are not available, thus precluding a straightforward study of the dynamical interactions among these genes. We therefore translate stage dependent data into time series. A feed-forward motif with multiple positive feed-backs can account for the observed delay between BCL11B versus TCF-1 and GATA-3 activation by Notch signalling. With a novel computational approach, all 32 possible interactions among Notch signalling, TCF-1, and GATA-3 are explored by translating combinatorial logic expressions into differential equations for BCL11B production rate. Results Our analysis reveals that only 3 of 32 possible configurations, where GATA-3 works as a dimer, are able to explain not only the time delay, but very importantly, also give rise to irreversibility. The winning models explain the data within the 95% confidence region and are consistent with regard to decay rates. Conclusions This first generation model for early T-cell specification has relatively few players. Yet it explains the gradual transition into a committed state with no return. Encoding logics in a rate equation setting allows determination of

  2. Irreversible Electroporation: Treatment Effect Is Susceptible to Local Environment and Tissue Properties

    PubMed Central

    Ahmed, Muneeb; Faroja, Mohammad; Moussa, Marwan; Wandel, Ayelet; Sosna, Jacob; Appelbaum, Liat; Nissenbaum, Isaac; Goldberg, S. Nahum

    2013-01-01

    Purpose To study the effects of the surrounding electrical microenvironment and local tissue parameters on the electrical parameters and outcome of irreversible electroporation (IRE) ablation in porcine muscle, kidney, and liver tissue. Materials and Methods Animal Care and Use Committee approval was obtained, and National Institutes of Health guidelines were followed. IRE ablation (n = 90) was applied in muscle (n = 44), kidney (n = 28), and liver (n = 18) tissue in 18 pigs. Two electrodes with tip exposure of 1.5–2 cm were used at varying voltages (1500–3000 V), pulse repetitions (n = 70–100), pulse length (70–100 µsec), and electrode spacing (1.5–2 cm). In muscle tissue, electrodes were placed exactly parallel, in plane, or perpendicular to paraspinal muscle fibers; in kidney tissue, in the cortex or adjacent to the renal medulla; and in liver tissue, with and without metallic or plastic plates placed 1–2 cm from electrodes. Ablation zones were determined at gross pathologic (90–120 minutes after IRE) and immunohistopathologic examination (6 hours after) for apoptosis and heat-shock protein markers. Multivariate analysis of variance with multiple comparisons and/or paired t tests and regression analysis were used for analysis. Results Mean (± standard deviation) ablation zones in muscle were 6.2 cm ± 0.3 × 4.2 cm ± 0.3 for parallel electrodes and 4.2 cm ± 0.8 × 3.0 cm ± 0.5 for in-plane application. Perpendicular orientation resulted in a cross-shaped zone. Orientation significantly affected IRE current applied (28.5–31.7A for parallel, 29.5–39.7A for perpendicular; P = .003). For kidney cortex, ovoid zones of 1.5 cm ± 0.1 × 0.5 cm ± 0.0 to 2.5 cm ± 0.1 × 1.3 cm ± 0.1 were seen. Placement of electrodes less than 5 mm from the medullary pyramids resulted in treatment effect arcing into the collecting system. For liver tissue, symmetric 2.7 cm ± 0.2 × 1.4 cm ± 0.3 coagulation areas were seen without the metallic plate but

  3. CBV_ASPECTS Improvement over CT_ASPECTS on Determining Irreversible Ischemic Lesion Decreases over Time

    PubMed Central

    Padroni, Marina; Boned, Sandra; Ribó, Marc; Muchada, Marian; Rodriguez-Luna, David; Coscojuela, Pilar; Tomasello, Alejandro; Cabero, Jordi; Pagola, Jorge; Rodriguez-Villatoro, Noelia; Juega, Jesus M.; Sanjuan, Estela; Molina, Carlos A.; Rubiera, Marta

    2016-01-01

    The Alberta Stroke Program Early CT Score (ASPECTS) is a useful scoring system for assessing early ischemic signs on noncontrast computed tomography (CT). Cerebral blood volume (CBV) on CT perfusion defines the core lesion assumed to be irreversibly damaged. We aim to explore the advantages of CBV_ASPECTS over CT_ASPECTS in the prediction of final infarct volume according to time. Methods Consecutive patients with anterior circulation stroke who underwent endovascular reperfusion according to initial CT_ASPECTS ≥7 were studied. CBV_ASPECTS was assessed blindly later on. Recanalization was defined as thrombolysis in cerebral ischemia score 2b-3. Final infarct volumes were measured on follow-up imaging. We compared ASPECTS on CBV and CT images, and defined ASPECTS agreement as: CT_ASPECTS - CBV_ASPECTS ≤1. Results Sixty-five patients, with a mean age of 67 ± 14 years and a median National Institutes of Health Stroke Scale score of 16 (range 10–20), were studied. The recanalization rate was 78.5%. The median CT_ASPECTS was 9 (range 8–10), and the CBV_ASPECTS was 8 (range 8–10). The mean time from symptoms to CT was 219 ± 143 min. Fifty patients (76.9%) showed ASPECTS agreement. The ASPECTS difference was inversely correlated to the time from symptoms to CT (r = −0.36, p < 0.01). A ROC curve defined 120 min as the best cutoff point after which the ASPECTS difference becomes more frequently ≤1. After 120 min, 89.5% of the patients showed ASPECTS agreement (as compared with 37.5% for <120 min, p < 0.01). CBV_ASPECTS but not CT_ASPECTS correlated with final infarct (r = −0.33, p < 0.01). However, if CT was done >2 h after symptom onset, CT_ASPECTS also correlated to final infarct (r = −0.39, p = 0.01). Conclusions In acute stroke, CBV_ASPECTS correlates with the final infarct volume. However, when CT is performed after 120 min from symptom onset, CBV_ASPECTS does not add relevant information to CT_ASPECTS. PMID:27781042

  4. The Influence of a Metal Stent on the Distribution of Thermal Energy during Irreversible Electroporation

    PubMed Central

    van den Bos, Willemien; Neal, Robert E.; van Lienden, Krijn P.; Besselink, Marc G. H.; van Gemert, Martin J. C.; van der Geld, Cees W. M.; Meijerink, Martijn R.; Klaessens, John H.; Verdaasdonk, Rudolf M.

    2016-01-01

    Purpose Irreversible electroporation (IRE) uses short duration, high-voltage electrical pulses to induce cell death via nanoscale defects resulting from altered transmembrane potential. The technique is gaining interest for ablations in unresectable pancreatic and hepatobiliary cancer. Metal stents are often used for palliative biliary drainage in these patients, but are currently seen as an absolute contraindication for IRE due to the perceived risk of direct heating of the metal and its surroundings. This study investigates the thermal and tissue viability changes due to a metal stent during IRE. Methods IRE was performed in a homogeneous tissue model (polyacrylamide gel), without and with a metal stent placed perpendicular and parallel to the electrodes, delivering 90 and 270 pulses (15–35 A, 90 μsec, 1.5 cm active tip exposure, 1.5 cm interelectrode distance, 1000–1500 V/cm, 90 pulses/min), and in-vivo in a porcine liver (4 ablations). Temperature changes were measured with an infrared thermal camera and with fiber-optic probes. Tissue viability after in-vivo IRE was investigated macroscopically using 5-triphenyltetrazolium chloride (TTC) vitality staining. Results In the gel, direct stent-heating was not observed. Contrarily, the presence of a stent between the electrodes caused a higher increase in median temperature near the electrodes (23.2 vs 13.3°C [90 pulses]; p = 0.021, and 33.1 vs 24.8°C [270 pulses]; p = 0.242). In-vivo, no temperature difference was observed for ablations with and without a stent. Tissue examination showed white coagulation 1mm around the electrodes only. A rim of vital tissue remained around the stent, whereas ablation without stent resulted in complete tissue avitality. Conclusion IRE in the vicinity of a metal stent does not cause notable direct heating of the metal, but results in higher temperatures around the electrodes and remnant viable tissue. Future studies should determine for which clinical indications IRE in the

  5. Surface and Size Effects in Statistical Mechanics: Irreversible Adsorption, Polymers and Interfaces.

    NASA Astrophysics Data System (ADS)

    Bartelt, Maria

    In this thesis work, three work problems address unifying features of surface and interfacial critical and growth phenomena. Emphasis is put into models that can be solved analytically but connections with numerical studies are also discussed. The first, most extensive study examines several aspects of irreversible, mono-layer and multilayer particle deposition on regular surfaces. Experimental studies have shown that such processes are relevant in describing, for instance, the adhesion of proteins on solid substrates, the kinetics of polymer reactions and some stages of multilayer formation in packed-bed experiments with colloidal suspensions. For the latter, Monte Carlo simulations of unscreened models have suggested similarities with critical phenomena (universal exponents and no intrinsic length scales) recently understood as a purely dynamic effect. In this thesis, multilayer studies established bounds for the validity of the mean-field models, at about 50% of the jamming coverage, and consideration of one-dimensional monolayer models yielded finite-size and boundary corrections, as small as {1over N!} for chains of N lattice spacings, but whose general form is possibly independent of the surface dimensionality. New interesting nonuniversal features are also examined in the late-stage dynamics of continuum adsorption of mixtures of particles. The calculations were carried out within a rate -equation approach, neglecting fluctuations in the deposition rates and screening among layers. The second topic treats, in the transfer matrix formalism, single polymer chains, in two and three dimensions, as directed self-avoiding walks undergoing conformational transitions near attractive surfaces. The adsorption-desorption behavior of the chain is temperature driven except for penetrable surfaces, as described in this thesis. The average fraction of adsorbed monomers vanishes linearly at the transition but the set of critical exponents is sensitive to the type of

  6. Irreversibility-line study in the polycrystalline Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 superconductor

    SciTech Connect

    Zaleski, H.; Razavi, F.S. )

    1991-05-01

    Measurements of irreversible magnetization in the superconducting state of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} compound have been made using a dc magnetometer. It was found that the irreversible magnetization is proportional to ({ital T}{minus}{ital T}{sup *}){sup {ital n}}, where {ital T}{sup *} is the field-dependent irreversibility temperature and the power {ital n} is of the order of 5. The irreversibility temperature obeys the relation 1{minus}{ital T}{sup *}/{ital T}{sub {ital c}}{proportional to}{ital B}{sup 2/3} at fields up to 0.6 T. At higher fields, {ital T}{sup *} was found to vary more slowly with the field, which is in agreement with previously published results.

  7. An intrinsically irreversible, neural-network-like approach to the Schrödinger equation and some results of application to drive nuclear synthesis research work

    SciTech Connect

    Abundo, Ugo

    2015-03-10

    An analogy is drawn among the irreversible evolution of a neural-network-based A.I., an information field associated to spacetime configurations and the behaviour of entities described by the Schrödinger equation.

  8. Beta-lactam antibiotic-induced platelet dysfunction: Evidence for irreversible inhibition of platelet activation in vitro and in vivo after prolonged exposure to penicillin

    SciTech Connect

    Burroughs, S.F.; Johnson, G.J. )

    1990-04-01

    beta-Lactam antibiotics cause platelet dysfunction with bleeding complications. Previous in vitro studies documented reversible inhibition of agonist-receptor interaction. This mechanism is inadequate to explain the effect of beta-lactam antibiotics in vivo. Platelet function does not return to normal immediately after drug treatment, implying irreversible inhibition of platelet function. We report here evidence of irreversible platelet functional and biochemical abnormalities after in vitro and in vivo exposure to beta-lactam antibiotics. Irreversible binding of (14C)-penicillin (Pen) occurred in vitro. After 24 hours' in vitro incubation with 10 to 20 mmol/L Pen, or ex vivo after antibiotic treatment, irreversible functional impairment occurred; but no irreversible inhibition of alpha 2 adrenergic receptors, measured with (3H)-yohimbine, or high-affinity thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors, measured with agonist (3H)-U46619 and antagonist (3H)-SQ29548, occurred. However, low-affinity platelet TXA2/PGH2 receptors were decreased 40% after Pen exposure in vitro or in vivo, indicating irreversible membrane alteration. Two postreceptor biochemical events were irreversibly inhibited in platelets incubated with Pen for 24 hours in vitro or ex vivo after antibiotic treatment. Thromboxane synthesis was inhibited 28.3% to 81.7%. Agonist-induced rises in cytosolic calcium ((Ca2+)i) were inhibited 40.1% to 67.5% in vitro and 26.6% to 52.2% ex vivo. Therefore, Pen binds to platelets after prolonged exposure, resulting in irreversible dysfunction attributable to inhibition of TXA2 synthesis and impairment of the rise in (Ca2+)i. The loss of low-affinity TXA2/PGH2 receptors suggests that the primary site of action of these drugs is on the platelet membrane.

  9. Trifunctional Agents as a Design Strategy for Tailoring Ligand Properties: Irreversible Inhibitors of A1 Adenosine Receptors†

    PubMed Central

    Boring, Daniel L.; Ji, Xiao-Duo; Zimmet, Jeff; Taylor, Kirk E.; Stiles, Gary L.

    2012-01-01

    The 1,3-phenylene diisothiocyanate conjugate of XAC (8-[4-[[[[(2-aminoethyl)amino]carbonyl]methyl]-oxy]phenyl]-l,3-dipropylxanthine, a potent A1 selective adenosine antagonist) has been characterized as an irreversible inhibitor of A1 adenosine receptors. To further extend this work, a series of analogues were prepared containing a third substituent in the phenyl isothiocyanate ring, incorporated to modify the physiochemical or spectroscopic properties of the conjugate. Symmetrical trifunctional cross-linking reagents bearing two isothiocyanate groups were prepared as general intermediates for cross-linking functionalized congeners and receptors. Xanthine isothiocyanate derivatives containing hydrophilic, fluorescent, or reactive substituents, linked via an amide, thiourea, or methylene group in the 5-position, were synthesized and found to be irreversible inhibitors of A1 adenosine receptors. The effects of the 5-substituent on water solubility and on the A1/A2 selectivity ratio derived from binding assays in rat brain membranes were examined. Inhibition of binding of [3H]-N6-(2-phenylisopropyl)-adenosine and [3H]CGS21680 (2-[[2-[4-(2-carboxyethyl)phenyl]ethyl]amino]adenosine-5′-N-ethylcarboxamide) at central A1 and A2 adenosine receptors, respectively, was measured. A conjugate of XAC and 1,3,5-triisothiocyanatobenzene was 894-fold selective for A1 receptors. Reporter groups, such as fluorescent dyes and a spin-label, were included as chain substituents in the irreversibly binding analogues, which were designed for spectroscopic assays, histochemical characterization, and biochemical characterization of the receptor protein. PMID:1868116

  10. Irreversible temperature quenching and antiquenching of photoluminescence of ZnS/CdS:Mn/ZnS quantum well quantum dots

    NASA Astrophysics Data System (ADS)

    Ding, X.; Dai, R. C.; Zhao, Z.; Wang, Z. P.; Sun, Z. Q.; Zhang, Z. M.; Ding, Z. J.

    2015-04-01

    An experimental observation on irreversible thermal quenching and antiquenching behavior is reported for photoluminescence of ZnS/CdS:Mn/ZnS quantum well quantum dots. The dual-color emissions, a blue emission centered at 430 nm and a Mn2+4T1 → 6A1 orange emission at 600 nm, were found to have different dependences of emission intensity on temperature in the range of 8-290 K. During temperature cooling/heating process, besides the usual thermal quenching, the orange emission shows stronger antiquenching behavior than that of blue emission in a certain temperature range.

  11. Work output and efficiency at maximum power of linear irreversible heat engines operating with a finite-sized heat source.

    PubMed

    Izumida, Yuki; Okuda, Koji

    2014-05-01

    We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart.

  12. Work output and efficiency at maximum power of linear irreversible heat engines operating with a finite-sized heat source.

    PubMed

    Izumida, Yuki; Okuda, Koji

    2014-05-01

    We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart. PMID:24856684

  13. Work Output and Efficiency at Maximum Power of Linear Irreversible Heat Engines Operating with a Finite-Sized Heat Source

    NASA Astrophysics Data System (ADS)

    Izumida, Yuki; Okuda, Koji

    2014-05-01

    We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart.

  14. Collective pinning behavior of intergranular Josephson vortices and the intergranular irreversibility line of high-{Tc} superconducting ceramics

    SciTech Connect

    Miu, L.

    1995-02-01

    The supercurrent-transport properties of YBa{sub 2}Cu{sub 3}O{sub {approximately}7} (Y:123) polycrystalline bulk sintered samples with random grain orientation were thoroughly investigated. The dissipation process in these materials occurs due to intergranular flux motion, rather than by weak-link quenching. It was found that the model which takes into consideration collective creep of intergranular vortices is self-consistent in describing the low-voltage-level current-voltage characteristics and the intergranular irreversibility line of high-{Tc} superconducting ceramics.

  15. Discovery of tumor-specific irreversible inhibitors of stearoyl CoA desaturase | Office of Cancer Genomics

    Cancer.gov

    A hallmark of targeted cancer therapies is selective toxicity among cancer cell lines. We evaluated results from a viability screen of over 200,000 small molecules to identify two chemical series, oxalamides and benzothiazoles, that were selectively toxic at low nanomolar concentrations to the same 4 of 12 human lung cancer cell lines. Sensitive cell lines expressed cytochrome P450 (CYP) 4F11, which metabolized the compounds into irreversible inhibitors of stearoyl CoA desaturase (SCD). SCD is recognized as a promising biological target in cancer and metabolic disease.

  16. Irreversible Hemichorea–Hemiballism in a Case of Nonketotic Hyperglycemia Presenting as the Initial Manifestation of Diabetes Mellitus

    PubMed Central

    Roy, Ujjawal; Das, Shyamal Kumar; Mukherjee, Adreesh; Biswas, Debsadhan; Pan, Koushik; Biswas, Atanu; Panwar, Ajay

    2016-01-01

    Background Hemichorea–hemiballism (HCHB) is a hyperkinetic movement disorder with features of both chorea and ballism occurring on the same side. Case report We present a case of HCHB due to nonketotic hyperglycemia (NKH) that was the initial presentation of diabetes and was irreversible clinically even after 6 months of optimal blood sugar control. Discussion Although HCHB due to hyperglycemia is a potentially reversible condition in the majority of patients, prolonged uncontrolled hyperglycemia may cause ischemic insult and persistent symptoms. Hyperglycemia should always be kept in the list of differentials while dealing with patients who are newly diagnosed with HCHB. PMID:27679748

  17. Irreversible Hemichorea–Hemiballism in a Case of Nonketotic Hyperglycemia Presenting as the Initial Manifestation of Diabetes Mellitus

    PubMed Central

    Roy, Ujjawal; Das, Shyamal Kumar; Mukherjee, Adreesh; Biswas, Debsadhan; Pan, Koushik; Biswas, Atanu; Panwar, Ajay

    2016-01-01

    Background Hemichorea–hemiballism (HCHB) is a hyperkinetic movement disorder with features of both chorea and ballism occurring on the same side. Case report We present a case of HCHB due to nonketotic hyperglycemia (NKH) that was the initial presentation of diabetes and was irreversible clinically even after 6 months of optimal blood sugar control. Discussion Although HCHB due to hyperglycemia is a potentially reversible condition in the majority of patients, prolonged uncontrolled hyperglycemia may cause ischemic insult and persistent symptoms. Hyperglycemia should always be kept in the list of differentials while dealing with patients who are newly diagnosed with HCHB.

  18. Radioactive Barium Ion Trap Based on Metal-Organic Framework for Efficient and Irreversible Removal of Barium from Nuclear Wastewater.

    PubMed

    Peng, Yaguang; Huang, Hongliang; Liu, Dahuan; Zhong, Chongli

    2016-04-01

    Highly efficient and irreversible capture of radioactive barium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, here we propose a concept of barium ion trap based on metal-organic framework (MOF) with a strong barium-chelating group (sulfate and sulfonic acid group) in the pore structures of MOFs. The functionalized MOF-based ion traps can remove >90% of the barium within the first 5 min, and the removal efficiency reaches 99% after equilibrium. Remarkably, the sulfate-group-functionalized ion trap demonstrates a high barium uptake capacity of 131.1 mg g(-1), which surpasses most of the reported sorbents and can selectively capture barium from nuclear wastewater, whereas the sulfonic-acid-group-functionalized ion trap exhibits ultrafast kinetics with a kinetic rate constant k2 of 27.77 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than existing sorbents. Both of the two MOF-based ion traps can capture barium irreversibly. Our work proposes a new strategy to design barium adsorbent materials and provides a new perspective for removing radioactive barium and other radionuclides from nuclear wastewater for environment remediation. Besides, the concrete mechanisms of barium-sorbent interactions are also demonstrated in this contribution.

  19. Structure-activity relationships for the irreversible blockade of nicotinic receptor agonist sites by lophotoxin and congeneric diterpene lactones

    SciTech Connect

    Culver, P.; Burch, M.; Potenza, C.; Wasserman, L.; Fenical, W.; Taylor, P.

    1985-11-01

    Lophotoxin, a diterpene lactone paralytic toxin from gorgonian corals of the genus Lophogorgia, inhibits ( SVI)-alpha-toxin binding to surface nicotinic receptors of BC3H-1 cells by irreversible occupation of the primary agonist sites. In contrast, receptor-bearing membrane fragments or detergent-solubilized receptors prepared from BC3H-1 cells are not susceptible to lophotoxin block. Thus, lophotoxin inhibition requires intact cells. However, when intact cells were incubated with lophotoxin, subsequent membrane-fragment preparation or detergent solubilization of the receptors did not diminish lophotoxin occupation of ( SVI)-alpha-toxin-binding sites, indicating that lophotoxin binds very tightly to nicotinic receptors. These studies further demonstrate that both surface and nonsurface nicotinic receptors of BC3H-1 cells are susceptible to irreversible occupation by lophotoxin, indicating that the lipophilic toxin freely permeates intact cells. The authors also examined several structural analogs of lophotoxin, one of which was equipotent with lophotoxin for inhibition of ( SVI)-alpha-toxin binding to intact cells and, notably, also blocked alpha-toxin binding to detergent-extracted receptor.

  20. FV-162 is a novel, orally bioavailable, irreversible proteasome inhibitor with improved pharmacokinetics displaying preclinical efficacy with continuous daily dosing.

    PubMed

    Wang, Z; Dove, P; Wang, X; Shamas-Din, A; Li, Z; Nachman, A; Oh, Y J; Hurren, R; Ruschak, A; Climie, S; Press, B; Griffin, C; Undzys, E; Aman, A; Al-awar, R; Kay, L E; O'Neill, D; Trudel, S; Slassi, M; Schimmer, A D

    2015-01-01

    Approved proteasome inhibitors have advanced the treatment of multiple myeloma but are associated with serious toxicities, poor pharmacokinetics, and most with the inconvenience of intravenous administration. We therefore sought to identify novel orally bioavailable proteasome inhibitors with a continuous daily dosing schedule and improved therapeutic window using a unique drug discovery platform. We employed a fluorine-based medicinal chemistry technology to synthesize 14 novel analogs of epoxyketone-based proteasome inhibitors and screened them for their stability, ability to inhibit the chymotrypsin-like proteasome, and antimyeloma activity in vitro. The tolerability, pharmacokinetics, pharmacodynamic activity, and antimyeloma efficacy of our lead candidate were examined in NOD/SCID mice. We identified a tripeptide epoxyketone, FV-162, as a metabolically stable, potent proteasome inhibitor cytotoxic to human myeloma cell lines and primary myeloma cells. FV-162 had limited toxicity and was well tolerated on a continuous daily dosing schedule. Compared with the benchmark oral irreversible proteasome inhibitor, ONX-0192, FV-162 had a lower peak plasma concentration and longer half-life, resulting in a larger area under the curve (AUC). Oral FV-162 treatment induced rapid, irreversible inhibition of chymotrypsin-like proteasome activity in murine red blood cells and inhibited tumor growth in a myeloma xenograft model. Our data suggest that oral FV-162 with continuous daily dosing schedule displays a favorable safety, efficacy, and pharmacokinetic profile in vivo, identifying it as a promising lead for clinical evaluation in myeloma therapy.

  1. Early history of extended irreversible thermodynamics (1953-1983): An exploration beyond local equilibrium and classical transport theory

    NASA Astrophysics Data System (ADS)

    Lebon, G.; Jou, D.

    2015-03-01

    This paper gives a historical account of the early years (1953-1983) of extended irreversible thermodynamics (EIT). The salient features of this formalism are to upgrade the thermodynamic fluxes of mass, momentum, energy, and others, to the status of independent variables, and to explore the consistency between generalized transport equations and a generalized version of the second law of thermodynamics. This requires going beyond classical irreversible thermodynamics by redefining entropy and entropy flux. EIT provides deeper foundations, closer relations with microscopic formalisms, a wider spectrum of applications, and a more exciting conceptual appeal to non-equilibrium thermodynamics. We first recall the historical contributions by Maxwell, Cattaneo, and Grad on generalized transport equations. A thermodynamic theory wide enough to cope with such transport equations was independently proposed between 1953 and 1983 by several authors, each emphasizing different kinds of problems. In 1983, the first international meeting on this theory took place in Bellaterra (Barcelona). It provided the opportunity for the various authors to meet together for the first time and to discuss the common points and the specific differences of their previous formulations. From then on, a large amount of applications and theoretical confirmations have emerged. From the historical point of view, the emergence of EIT has been an opportunity to revisit the foundations and to open new avenues in thermodynamics, one of the most classical and well consolidated physical theories.

  2. Enhancing the Bipolar Redox Cycling Efficiency of Plane-Recessed Microelectrode Arrays by Adding a Chemically Irreversible Interferent.

    PubMed

    He, Dingwen; Yan, Jiawei; Zhu, Feng; Zhou, Yongliang; Mao, Bingwei; Oleinick, Alexander; Svir, Irina; Amatore, Christian

    2016-09-01

    The individual electrochemical anodic responses of dopamine (DA), epinephrine (EP), and pyrocatechol (CT) were investigated at arrays of recessed gold disk-microelectrodes arrays (MEAs) covered by a gold plane electrode and compared to those of their binary mixture (CT and EP) when the top-plane electrode was operated as a bipolar electrode or as a collector. The interferent species (EP) displays a chemically irreversible wave over the same potential range as the chemically reversible ones of DA or CT. As expected, in the generator-collector (GC) mode, EP did not contribute to the redox cycling amplification that occurred only for DA or CT. Conversely, in the bipolar mode, the presence of EP drastically increased the bipolar redox cycling efficiency of DA and CT. This evidenced that the chemically irreversible oxidation of EP at the anodic poles of the top plane floating electrode provided additional electron fluxes that were used to more efficiently reduce the oxidized DA or CT species at the cathodic poles. This suggests an easy experimental strategy for enhancing the bipolar efficiency of MEAs up to reach a performance identical to that achieved when the same MEAs are operated in a GC mode. PMID:27490270

  3. Time dependency and irreversibility of water desorption by drinking-water treatment residuals: implications for sorption mechanisms.

    PubMed

    Makris, Konstantinos C; Harris, Willie G

    2006-02-01

    Drinking-water treatment residuals (WTRs) are being evaluated as cost-effective sorption media for use in environmental remediation. Data from previous work have suggested that intraparticle phosphorus (P) diffusion into micropores is the rate-limiting mechanism of P sorption by WTRs. We used isothermal thermogravimetric analysis (TG) to study water desorption/resorption dynamics as they relate to steric diffusion rate limitations for prospective sorbates. Results showed that air-dried WTR particles contain significant amounts of water. Only about 40% of water desorbed isothermally (70 degrees C) for 10 h was readsorbed when particles were reexposed to ambient temperature and moisture conditions. This hysteresis related closely with time dependency of water loss, suggesting steric diffusional hindrance of water re-adsorption by meso- and micropores. The irreversibly desorbed water may be the component requiring increased kinetic energy to overcome diffusional resistance. Another possible factor in irreversibility could be pore shrinkage. Samples incubated for 12 months at 70 degrees C prior to TG analysis showed no hysteresis at 70 degrees C. Isothermal water losses with time fit well (r2 = 0.95) the diffusion model of Kabai. These results are consistent with an aqueous pore network that would account for high phosphorus sorption capacity and hysteresis that has been recently documented for WTRs.

  4. X-ray photon correlation spectroscopy studies of structural irreversibility in a colloidal gel subjected to oscillatory shear flow

    NASA Astrophysics Data System (ADS)

    Kweon, Mu Sung; Burghardt, Wesley; Ramakrishnan, Subramanian; Louis, Golda; Thomas, Danica; Narayanan, Suresh

    2015-03-01

    X-ray photon correlation spectroscopy (XPCS) is used to probe the microscopic structural reversibility in a colloidal gel subjected to oscillatory shear flow. Silicon dioxide particles in decalin aggregate into a gel structure as a result of depletion interactions associated with dissolved polystyrene molecules. XPCS studies on aged quiescent gels show negligible structural dynamics on time scales of tens of seconds. Such samples were subjected to oscillatory shear with varying stain amplitude using a rheometer installed in the XPCS beam line and x-ray capable polycarbonate fixtures; this enable simultaneous rheological measurements during the XPCS experiment. In the presence of unidirectional shear flow, the decay of the XPCS autocorrelation function is dominated by the convective motion induced by the applied deformation. In oscillatory shearing of samples in the absence of significant structural relaxation, the autocorrelation function becomes periodic, returning to its initial value once every oscillation period. At higher strains, irreversible motions at the microscopic level lead to decay in the 'echos' of the autocorrelation function. Interestingly, structural irreversibility is detected by XPCS only at strains that are significantly higher than those at which nonlinearity

  5. Reversible and irreversible small molecule inhibitors of monoamine oxidase B (MAO-B) investigated by biophysical techniques.

    PubMed

    Rojas, Rafael J; Edmondson, Dale E; Almos, Terri; Scott, Roderick; Massari, Mark E

    2015-02-15

    Monoamine oxidase B (MAO-B) plays a key role in the metabolism of dopamine, a neurotransmitter critical for the maintenance of cognitive function. Consequently, MAO-B is an important therapeutic target for disorders characterized by a decline in dopaminergic neurotransmission, including Parkinson's disease (PD). An emerging strategy in drug discovery is to utilize the biophysical approaches of thermal shift and isothermal titration calorimetry (ITC) to gain insight into binding modality and identify thermodynamically privileged chemical scaffolds. Described here is the development of such approaches for reversible and irreversible small molecule inhibitors of MAO-B. Investigation of soluble recombinant MAO-B revealed mechanism-based differences in the thermal shift and binding thermodynamic profiles of MAO-B inhibitors. Irreversible inhibitors demonstrated biphasic protein melt curves, large enthalpically favorable and entropically unfavorable binding, in contrast to reversible compounds, which were characterized by a dose-dependent increase in thermal stability and enthalpically-driven binding. The biophysical approaches described here aim to facilitate the discovery of next-generation MAO-B inhibitors.

  6. Large irreversible non-180° domain switching after poling treatment in Pb(Zr, Ti)O3 films

    NASA Astrophysics Data System (ADS)

    Ehara, Yoshitaka; Yasui, Shintaro; Oikawa, Takahiro; Shiraishi, Takahisa; Oshima, Naoya; Yamada, Tomoaki; Imai, Yasuhiko; Sakata, Osami; Funakubo, Hiroshi

    2016-05-01

    (11 1 ¯ )/(111)-oriented rhombohedral Pb(Zr0.65Ti0.35)O3 films with different domain fractions were epitaxially grown on various single crystals. The volume fraction of (111)-polar-axis oriented domains in as-deposited films, Vpol.(as-depo.), was controlled by selecting a single crystal substrate with a different thermal expansion coefficient. Applying an electric field, referred to as "poling treatment", resulted in irreversible non-180° domain switching from the (11 1 ¯ )-oriented domain (non-polar-axis) to the (111)-oriented domain (polar-axis), which was observed by synchrotron X-ray diffraction. Remanent polarization (Pr) values were higher than those estimated using the proportional relationship with Vpol.(as-depo.). However, the experimental Pr values were in good agreement with the values estimated using the volume fraction of (111)-oriented domains after applying the poling treatment. In rhombohedral Pb(Zr0.65Ti0.35)O3 films, 30%-50% of the (11 1 ¯ )-oriented domains switched irreversibly to (111)-oriented domains as a result of the poling treatment. The present results show that the domain structures of films may change dramatically after the poling process, and both before and after the poling state should be characterized in order to interpret polarization and piezoelectric behaviors. This study helps to clarify the ferroelectric and piezoelectric properties of Pb(Zr, Ti)O3 films after poling treatment.

  7. The relationship between the level of salivary alpha amylase activity and pain severity in patients with symptomatic irreversible pulpitis

    PubMed Central

    Shahriari, Shahriar; Goodarzi, Mohammad Taghi; Moghimbeigi, Abbas; Jazaeri, Mina; Babaei, Parisa

    2013-01-01

    Objectives Assessment of dental pain severity is very challenging in dentistry. Previous studies have suggested that elevated salivary alpha amylase may contribute to increased physical stresses. There is a close association between salivary alpha amylase and plasma norepinephrine under stressful physical conditions. The aim of this study was to evaluate the relationship between pain severity and salivary alpha amylase levels in patients with symptomatic irreversible pulpitis. Materials and Methods Thirty-six patients (20 females and 16 males) with severe tooth pain due to symptomatic irreversible pulpitis were selected. The visual analogue scale (VAS) score was used to assess the pain severity in each patient. Unstimulated whole saliva was collected, and the level of alpha amylase activity was assessed by the spectrophotometric method. Statistical analysis was performed using SPSS 13. Results The level of alpha amylase was significantly increased in the saliva in association with pain severity assessed by VAS. The salivary alpha amylase was also elevated with increased age and in males. Conclusions There was a significant correlation between the VAS pain scale and salivary alpha amylase level, which indicates this biomarker may be a good index for the objective assessment of pain intensity. PMID:24010080

  8. Evaluation of reversible and irreversible degradation rates of polymer electrolyte membrane fuel cells tested in automotive conditions

    NASA Astrophysics Data System (ADS)

    Gazdzick, Pawel; Mitzel, Jens; Garcia Sanchez, Daniel; Schulze, Mathias; Friedrich, K. Andreas

    2016-09-01

    This work provides single cell durability tests of membrane electrode assemblies in dynamic operation regularly interrupted by recovery procedures for the removal of reversible voltage losses. Degradation rates at different loads in one single test can be determined from these tests. Hence, it is possible to report degradation rates versus current density instead of a single degradation rate value. A clear discrimination between reversible and irreversible voltage loss rates is provided. The irreversible degradation rate can be described by a linear regression of voltage values after the recovery steps. Using voltage values before refresh is less adequate due to possible impacts of reversible effects. The reversible contribution to the voltage decay is dominated by an exponential decay after restart, eventually turning into a linear one. A linear-exponential function is proposed to fit the reversible voltage degradation. Due to this function, the degradation behavior of an automotive fuel cell can be described correctly during the first hours after restart. The fit parameters decay constant, exponential amplitude and linear slope are evaluated. Eventually, the reasons for the voltage recovery during shutdown are analyzed showing that ionomer effects in the catalyst layer and/or membrane seem to be the key factor in this process.

  9. In Situ TEM Study of Reversible and Irreversible Electroforming in Pt/Ti:NiO/Pt Heterostructures

    SciTech Connect

    D'Aquila, Kenneth; Liu, Yuzi; Iddir, Hakim; Petford-Long, Amanda K.

    2015-05-01

    Experimental verification of the microscopic origin of resistance switching in metal/oxide/metal heterostructures is needed for applications in non-volatile memory and neuromorphic computing. Numerous reports suggest that resistance switching in NiO is caused by local reduction of the oxide layer into nanoscale conducting filaments, but few reports have shown experimental evidence correlating electroforming with site-specific changes in composition. We have investigated the mechanisms of reversible and irreversible electroforming in 250–500 nm wide pillars patterned from a single Ta/Ti/Pt/Ti-doped NiO/Pt/Ta heterostructure and have shown that these can coexist within a single sample. We performed in situ transmission electron microscopy (TEM) electroform- ing and switching on each pillar to correlate the local electron transport behavior with microstructure and composition in each pillar. DFT calculations fitted to electron energy loss spectroscopy data showed that the Ti-doped NiO layer is partially reduced after reversible electroforming, with the formation of oxygen vacancies ordered into lines in the <110> direction. However, under the same probing conditions, adjacent pillars show irreversible electroforming caused by electromigration of metallic Ta to form a single bridge across the oxide layer. We propose that the different electroforming behaviors are related to microstructural variations across the sample and may lead to switching variability.

  10. Prognostic factors in multiple myeloma: definition of risk groups in 410 previously untreated patients: a Grupo Argentino de Tratamiento de la Leucemia Aguda study.

    PubMed

    Corrado, C; Santarelli, M T; Pavlovsky, S; Pizzolato, M

    1989-12-01

    Four hundred ten previously untreated multiple myeloma patients entered onto two consecutive Grupo Argentino de Tratamiento de la Leucemia Aguda (GATLA) protocols were analyzed to identify significant prognostic factors influencing survival. The univariate analysis selected the following variables: performance status, renal function, percentage of bone marrow plasma cells at diagnosis, hemoglobin, and age. A multivariate analysis showed that performance status, renal function, percentage of bone marrow plasma cells, hemoglobin, and age were the best predictive variables for survival. A score was assigned to each patient according to these variables, which led to their classification in three groups: good, intermediate, and poor risk, with a probability of survival of 26% and 10% at 96 months, and 5% at 56 months, and median survival of 60, 37, and 14 months, respectively (P = .0000). In our patient population, this model proved to be superior to the Durie-Salmon staging system in defining prognostic risk groups, and separating patients with significantly different risks within each Durie-Salmon stage.

  11. Irreversible Thermal Denaturation of β-Hemocyanin of Helix pomatia and its Substructures Studied by Differential Scanning Calorimetry

    NASA Astrophysics Data System (ADS)

    Idakieva, Krassimira; Gielens, Constant; Siddiqui, Nurul I.; Doumanova, Lyubka; Vasseva, Boyka; Kostov, Georgi; Shnyrov, Valery L.

    2007-09-01

    The thermal denaturation of β -hemocyanin from the gastropod Helix pomatia (β -HpH) at neutral pH was studied by means of differential scanning calorimetry (DSC). The denaturation was completely irreversible as judged by the absence of any endotherm on rescanning previously scanned samples. Two transitions, with apparent transition temperatures (Tm) of ca. 84 °C (main transition) and ca. 88 °C (minor transition), were detected by DSC in 20 mM MOPS buffer, containing 0.1 M NaCl, 5mM CaCl2 and 5 mM MgCl2 at pH 7.2 (buffer A), using a heating rate of 1.0 Kmin-1. Both Tm values were dependent on the scanning rate, suggesting that the thermal denaturation of β -HpH is a kinetically controlled process. The Tm and specific enthalpy values (ΔHcal) for the thermal denaturation of β -HpH were found to be independent of the protein concentration, indicating that the dissociation of the protein into monomers does not take place before the rate-determining step of the process of thermal unfolding started. A successive annealing procedure was applied to obtain the experimental deconvolution of the irreversible thermal transitions. These transitions are tentatively attributed to the denaturation of, respectively, the wall (main transition) and the collar of the β -HpH molecule. The activation energies (EA) of both transitions were found to be similar (about 500 kJ mol-1). In 130 mM glycine/NaOH buffer, pH 9.6 (buffer B), with β -HpH dissociated into subunits, the calorimetric profile had a more complex character. This could be ascribed to a different stability of the functional units (FUs) constituting the β -HpH subunit. FU d, which in the cylindrical didecameric β -HpH molecule is located in the wall, was markedly less stable than FU g, which belongs to the collar. The thermal denaturation of FUs d and g was described by the two-state irreversible model. On the basis of this model, the parameters of the Arrhenius equation were calculated.

  12. Reversible and irreversible magnetization of the Chevrel-phase superconductor PbMo{sub 6}S{sub 8}

    SciTech Connect

    Zheng, D.N.; Ramsbottom, H.D.; Hampshire, D.P.

    1995-11-01

    Magnetic measurements have been carried out on the hot-isostatically-pressed Chevrel-phase superconductor PbMo{sub 6}S{sub 8} at temperatures from 4.2 K to {ital T}{sub {ital c}} and for magnetic fields up to 12 T. The results show that for the PbMo{sub 6}S{sub 8} compound there is a wide magnetically reversible region, between the irreversibility field {ital B}{sub irr} and the upper critical field {ital B}{sub {ital c}2}, on the isothermal magnetic hysteresis curves. The {ital B}{sub irr}({ital T}) line, i.e., the irreversibility line, was found to obey a power-law expression: {ital B}{sub irr}={ital B}{sup *}(1{minus}{ital T}/{ital T}{sub {ital c}}){sup {alpha}} with {alpha}{approx}1.5. Magnetic relaxation measurements revealed that the flux-creep effect in the material studied is substantial and is greater than those observed in conventional metallic alloys, but smaller than in high-temperature superconductors. The existence of the irreversibility line and pronounced flux-creep effect in PbMo{sub 6}S{sub 8} is attributed to the short coherence length of the material. From the reversible magnetization data, the values of the penetration depth, the coherence length, and the critical fields are obtained together with the Ginzburg-Landau parameter {kappa}. At 4.2 K, the critical current density {ital J}{sub {ital c}} is 10{sup 9} A m{sup {minus}2} at zero field, and decreases to 2{times}10{sup 8} A m{sup {minus}2} at 10 T. Pinning force curves measured at different temperatures obey a Kramer-scaling law of the form: {ital F}{sub {ital p}}(={ital J}{sub {ital c}}{times}{ital B}){proportional_to}{ital b}{sup 1/2}(1{minus}{ital b}){sup 2}, which indicates that the {ital J}{sub {ital c}} is limited by one predominant flux-pinning mechanism.

  13. Performance optimization of an air-standard irreversible dual-atkinson cycle engine based on the ecological coefficient of performance criterion.

    PubMed

    Gonca, Guven; Sahin, Bahri

    2014-01-01

    This paper presents an ecological performance analysis and optimization for an air-standard irreversible Dual-Atkinson cycle (DAC) based on the ecological coefficient of performance (ECOP) criterion which includes internal irreversibilities, heat leak, and finite-rate of heat transfer. A comprehensive numerical analysis has been realized so as to investigate the global and optimal performances of the cycle. The results obtained based on the ECOP criterion are compared with a different ecological function which is named as the ecologic objective-function and with the maximum power output conditions. The results have been attained introducing the compression ratio, cut-off ratio, pressure ratio, Atkinson cycle ratio, source temperature ratio, and internal irreversibility parameter. The change of cycle performance with respect to these parameters is investigated and graphically presented. PMID:25170525

  14. The irreversibility line of (Bi,Pb) sub 2 Sr sub 2 Ca sub 2 Cu sub 3 O sub 10 determined by dc magnetization

    SciTech Connect

    Green, S.M.; Lobb, C.J.; Greene, R.L. . Dept. of Physics and Astronomy)

    1991-03-01

    This paper analyzes the irreversibility line, H*(T), of c-axis aligned Bi{sub 1.65}Pb{sub 0.35}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} based on dc magnetization measurements for fields up to 50 kOe. Its temperature dependence is found to depend strongly on the criterion used to determine irreversibility. Using sensitivity criteria of 5, 15, and 25 {times} 10{sup {minus}5} emu, the low field data fit H* {approximately} H{sub 0}* 1-T/T{sub c}{sup {gamma}} with {gamma} = 2.3--2.6 and H{sub 0}* {approximately} 1.8 {times} 19{sup 4} emu. Using fitted curves, the irreversibility line follows this equation over the entire field range with {gamma} = 3.2 and H{sub 0}* {approximately} 35 {times} 10{sup 4} emu.

  15. Influence of [ital H][sub [ital c]1] on the irreversibility line in YBa[sub 2]Cu[sub 3]O[sub 7] thin films

    SciTech Connect

    Civale, L.; Worthington, T.K.; Gupta, A. )

    1993-09-01

    The irreversibility line of a type-II superconductor separates the [ital H]-[ital T] plane into a region above the line where the critical current is zero and the magnetic properties are reversible, and a region below where a critical current is observed and the magnetic properties are irreversible. Although there is great controversy over the various models proposed to explain these observations, they all depend on the existence of magnetic-flux quanta in the sample. This implies that the irreversibility line cannot cross [ital H][sub [ital c]1]([ital T]). In bulk samples, assuming that the observed functional forms are maintained, this would be expected to occur much too close to [ital T][sub [ital c

  16. Construction of crystalline 2D covalent organic frameworks with remarkable chemical (acid/base) stability via a combined reversible and irreversible route.

    PubMed

    Kandambeth, Sharath; Mallick, Arijit; Lukose, Binit; Mane, Manoj V; Heine, Thomas; Banerjee, Rahul

    2012-12-01

    Two new chemically stable [acid and base] 2D crystalline covalent organic frameworks (COFs) (TpPa-1 and TpPa-2) were synthesized using combined reversible and irreversible organic reactions. Syntheses of these COFs were done by the Schiff base reactions of 1,3,5-triformylphloroglucinol (Tp) with p-phenylenediamine (Pa-1) and 2,5-dimethyl-p-phenylenediamine (Pa-2), respectively, in 1:1 mesitylene/dioxane. The expected enol-imine (OH) form underwent irreversible proton tautomerism, and only the keto-enamine form was observed. Because of the irreversible nature of the total reaction and the absence of an imine bond in the system, TpPa-1 and TpPa-2 showed strong resistance toward acid (9 N HCl) and boiling water. Moreover, TpPa-2 showed exceptional stability in base (9 N NaOH) as well.

  17. Performance Optimization of an Air-Standard Irreversible Dual-Atkinson Cycle Engine Based on the Ecological Coefficient of Performance Criterion

    PubMed Central

    Gonca, Guven; Sahin, Bahri

    2014-01-01

    This paper presents an ecological performance analysis and optimization for an air-standard irreversible Dual-Atkinson cycle (DAC) based on the ecological coefficient of performance (ECOP) criterion which includes internal irreversibilities, heat leak, and finite-rate of heat transfer. A comprehensive numerical analysis has been realized so as to investigate the global and optimal performances of the cycle. The results obtained based on the ECOP criterion are compared with a different ecological function which is named as the ecologic objective-function and with the maximum power output conditions. The results have been attained introducing the compression ratio, cut-off ratio, pressure ratio, Atkinson cycle ratio, source temperature ratio, and internal irreversibility parameter. The change of cycle performance with respect to these parameters is investigated and graphically presented. PMID:25170525

  18. Quantum mechanics/molecular mechanics modeling of fatty acid amide hydrolase reactivation distinguishes substrate from irreversible covalent inhibitors.

    PubMed

    Lodola, Alessio; Capoferri, Luigi; Rivara, Silvia; Tarzia, Giorgio; Piomelli, Daniele; Mulholland, Adrian; Mor, Marco

    2013-03-28

    Carbamate and urea derivatives are important classes of fatty acid amide hydrolase (FAAH) inhibitors that carbamoylate the active-site nucleophile Ser241. In the present work, the reactivation mechanism of carbamoylated FAAH is investigated by means of a quantum mechanics/molecular mechanics (QM/MM) approach. The potential energy surfaces for decarbamoylation of FAAH covalent adducts, derived from the O-aryl carbamate URB597 and from the N-piperazinylurea JNJ1661610, were calculated and compared to that for deacylation of FAAH acylated by the substrate oleamide. Calculations show that a carbamic group bound to Ser241 prevents efficient stabilization of transition states of hydrolysis, leading to large increments in the activation barrier. Moreover, the energy barrier for the piperazine carboxylate was significantly lower than that for the cyclohexyl carbamate derived from URB597. This is consistent with experimental data showing slowly reversible FAAH inhibition for the N-piperazinylurea inhibitor and irreversible inhibition for URB597.

  19. Characterization of irreversible kinase inhibitors by directly detecting covalent bond formation: a tool for dissecting kinase drug resistance.

    PubMed

    Klüter, Sabine; Simard, Jeffrey R; Rode, Haridas B; Grütter, Christian; Pawar, Vijaykumar; Raaijmakers, Hans C A; Barf, Tjeerd A; Rabiller, Matthias; van Otterlo, Willem A L; Rauh, Daniel

    2010-12-10

    Targeting protein kinases in cancer therapy with irreversible small-molecule inhibitors is moving to the forefront of kinase-inhibitor research and is thought to be an effective means of overcoming mutation-associated drug resistance in epidermal growth factor receptor kinase (EGFR). We generated a detection technique that allows direct measurements of covalent bond formation without relying on kinase activity, thereby allowing the straightforward investigation of the influence of steric clashes on covalent inhibitors in different resistant kinase mutants. The obtained results are discussed together with structural biology and biochemical studies of catalytic activity in both wild-type and gatekeeper mutated kinase variants to draw conclusions about the impact of steric hindrance and increased catalytic activity in drug-resistant kinase variants. PMID:21080395

  20. Percutaneous Irreversible Electroporation of a Large Centrally Located Hepatocellular Adenoma in a Woman with a Pregnancy Wish

    SciTech Connect

    Scheffer, Hester J. Melenhorst, Marleen C. A. M. Tilborg, Aukje A. J. M. van; Nielsen, Karin; Nieuwkerk, Karin M. van Vries, Richard A. de; Tol, Petrousjka van den; Meijerink, Martijn R.

    2015-08-15

    Irreversible electroporation (IRE) is a novel image-guided ablation technique that is rapidly gaining popularity in the treatment of malignant liver tumors located near large vessels or bile ducts. We describe a 28-year-old female patient with a 5 cm large, centrally located hepatocellular adenoma who wished to get pregnant. Regarding the risk of growth and rupture of the adenoma caused by hormonal changes during pregnancy, treatment of the tumor was advised prior to pregnancy. However, due to its central location, the tumor was considered unsuitable for resection and thermal ablation. Percutaneous CT-guided IRE was performed without complications and led to rapid and impressive tumor shrinkage. Subsequent pregnancy and delivery went uncomplicated. This case report suggests that the indication for IRE may extend to the treatment of benign liver tumors that cannot be treated safely otherwise.