Infinitesimal Amount Research Articles

FRET sensor-based quantification of intracellular trehalose in mammalian cells.

Trehalose acts as a stress protectant and an autophagy inducer in mammalian cells. The molecular mechanisms of action remain obscure because intracellular trehalose at micromolar level is difficult to quantitate. Here, we show a novel trehalose monitoring technology based on FRET. FLIP-suc90μ∆1Venus sensor expressed in mammalian cells enables to quickly and non-destructively detect an infinitesimal amount of intracellular trehalose.

Topological Weyl superconductor to diffusive thermal Hall metal crossover in theBphase ofUPt3

The recent phase sensitive measurements in the superconducting $B$-phase of UPt$_3$ provide strong evidence for the triplet, chiral $k_z(k_x \pm ik_y)^2$ pairing symmetries, which endow the Cooper pairs with orbital angular momentum projections $L _z= \pm 2$ along the $c$-axis. In the absence of disorder such pairing can support both line and point nodes, and both types of nodal quasiparticles exhibit nontrivial topology in the momentum space. The point nodes, located at the intersections of the closed Fermi surfaces with the $c$-axis, act as the double monopoles and the antimonopoles of the Berry curvature, and generalize the notion of Weyl quasiparticles. Consequently, the $B$ phase should support an anomalous thermal Hall effect, the polar Kerr effect, in addition to the protected Fermi arcs on the (1,0,0) and the (0,1,0) surfaces. The line node at the Fermi surface equator acts as a vortex loop in the momentum space and gives rise to the zero energy, dispersionless Andreev bound states on the (0,0,1) surface. At the transition from the $B$-phase to the $A$-phase, the time reversal symmetry is restored, and only the line node survives inside the $A$-phase. As both line and double-Weyl point nodes possess linearly vanishing density of states, we show that weak disorder acts as a marginally relevant perturbation. Consequently, an infinitesimal amount of disorder destroys the ballistic quasiparticle pole, while giving rise to a diffusive phase with a finite density of states at the zero energy. The resulting diffusive phase exhibits $T$-linear specific heat, and an anomalous thermal Hall effect. We predict that the low temperature thermodynamic and transport properties display a crossover between a ballistic thermal Hall semimetal and a diffusive thermal Hall metal.

Effect of Hydogen Sulfide Ions on a Passivation Behavior of Type-316L Stainless Steel

Manganese sulfide (MnS) is known to providing pitting corrosion sites in stainless steels [1, 2]. The roles of MnS on pitting corrosion have been generally agreed that the electrochemical and/or chemical reactions of MnS release S species [1-3]. Although many suggestions have been discussed to understand an initiation of pitting corrosion, it is still difficult to elucidate an initiation process of pitting corrosion because of intricate steps of a pit initiation which includes passivity and complicated passivity breakdown. It is important to investigate detailed studies for understanding the effects of primal S species released from MnS on a passivity behavior of stainless steel. Despite the fact that MnS chemically dissolves and releases hydrogen sulfide ion (HS–) as primary reaction, very little attention is given to the effects of HS– on a passive behavior of stainless steel which can be additional roles to understand an initial stage of a pitting corrosion. The authors have developed a liquid-phase ion gun (LPIG) to release an infinitesimal amount (ppm-order) of HS– by reducing a silver/silver sulfide microelectrode and applied to induce the local sulfidation on a silver surface [4]. The application of LPIG enables to elucidate the passivation and/or depassivation of stainless steels induced by hydrogen sulfide ions. In this study, effects of HS–on passivity of type-316L stainless steel were examined by using LPIG for the first time. The fabrication procedure of a silver/silver sulfide LPIG microelectrode was basically identical with that reported previously [4]. A diameter of the microelectrode was 500 µm. A three-electrode electrochemical cell with a platinum counter electrode and an Ag/AgCl/sat. KCl reference electrode (SSE) was used for electrochemical measurements of a substrate electrode of the stainless steel. The surface of the stainless steel was passivated by a potentiostatic polarization at 0.4 VSSE for 100 s. When a distance between microelectrode and substrate electrode was sustained with 125 μm, the microelectrode was connected with the substrate electrode and galvanostaticaly reduced to generate HS– by using a battery-driving DC signal source in pH 8.4 boric acid-borate buffer solution, while the substrate stainless steel electrode was continuously polarized at 0.4 VSSE. Electrochemical impedance was measured at a constant frequency of 15 Hz and in a frequency range of 10−2 to 104 Hz with an amplitude voltage of 10 mV. Mott-Schottky (MS) analysis was also conducted at a frequency of 15 Hz while the applied potential was stepwise shifted from the potential of 0.4 VSSE to –0.4 VSSE. Moreover, silver wire and tungsten wire electrodes were used to estimate concentration of HS− and pH value, respectively, in the narrow space between microelectrode and substrate electrode before and after the galvanostatic polarization of LPIG microelectrode. Auger electron spectroscopy (AES) was also used to analyze the passive film on the stainless steel when it was formed with or without presence of HS–generation by LPIG. From the open circuit potential measurement of the silver and tungsten wire electrodes during the LPIG polarization for generation of HS−, concentration of HS− and pH values in the narrow space were estimated with less than 10 ppm and ca. pH 9.5, respectively. During potentiostatic polarization of the stainless steel and LPIG microelectrode, current density increased with increase in concentration of HS−. It is considered that further reactions could be induced by HS− during the passivation of the steel surface. The impedance at 15 Hz decreased during the polarization in the presence of HS− by LPIG, while that sustained after a dilution of HS− by stopping the generation of HS− and removing the microelectrode to the solution bulk. Moreover, a charge transfer resistance of passive film formed in the presence of HS− decreased with increase in HS– concentration. MS results indicated that the more defective n-type passive film is formed in the presence of HS− than that formed without presence of HS−. AES results revealed the increase of metal cations and the decrease of oxygen anion in the passive film formed in the presence of HS−. It was indicated that the passive film formed on type-316L stainless steel at 0.4 VSSE in pH 8.4 buffer solution was unstable due to the presence of HS−.

Mechanism of Asymmetric Hydrogenation of Aromatic Ketones Catalyzed by a Combined System of Ru(π-CH2C(CH3)CH2)2(cod) and the Chiral sp(2)N/sp(3)NH Hybrid Linear N4 Ligand Ph-BINAN-H-Py.

The combination of a Goodwin-Lions-type chiral N4 ligand, (R)-Ph-BINAN-H-Py ((R)-3,3'-diphenyl-N(2),N(2')-bis((pyridin-2-yl)methyl)-1,1'-binaphthyl-2,2'-diamine; L), with Ru(π-CH2C(CH3)CH2)2(cod) (A) (cod = 1,5-cyclooctadiene) catalyzes the hydrogenation of acetophenone (AP) to (R)-1-phenylethanol (PE) with a high enantiomer ratio (er). Almost no Ru complex forms, with A and L remaining intact throughout the reaction while generating PE quantitatively according to [PE] = k(obs)t(2). An infinitesimal amount of reactive and unstable RuH2L (B) with C2-Λ-cis-α stereochemistry is very slowly and irreversibly generated from A by the action of H2 and L, which rapidly catalyzes the hydrogenation of AP via Noyori's donor-acceptor bifunctional mechanism. A CH-π-stabilized Si-face selective transition state, CSi, gives (R)-PE together with an intermediary Ru amide, D, which is inhibited predominantly by formation of the Ru enolate of AP. The rate-determining hydrogenolysis of D completes the cycle. The time-squared term relates both to the preliminary step before the cycle and to the cycle itself, with a highly unusual eight-order difference in the generation and turnover frequency of B. This mechanism is fully supported by a series of experiments including a detailed kinetic study, rate law analysis, simulation of t/[PE] curves with fitting to the experimental observations at the initial reaction stage, X-ray crystallographic analyses of B-related octahedral metal complexes, and Hammett plot analyses of electronically different substrates and ligands in their enantioselectivities.

Return to the Poissonian city

Consider the following random spatial network: in a large disk, construct a network using a stationary and isotropic Poisson line process of unit intensity. Connect pairs of points using the network, with initial/final segments of the connecting path formed by travelling off the network in the opposite direction to that of the destination/source. Suppose further that connections are established using ‘near geodesics’, constructed between pairs of points using the perimeter of the cell containing these two points and formed using only the Poisson lines not separating them. If each pair of points generates an infinitesimal amount of traffic divided equally between the two connecting near geodesics, and if the Poisson line pattern is conditioned to contain a line through the centre, then what can be said about the total flow through the centre? In Kendall (2011) it was shown that a scaled version of this flow has asymptotic distribution given by the 4-volume of a region in 4-space, constructed using an improper anisotropic Poisson line process in an infinite planar strip. Here we construct a more amenable representation in terms of two ‘seminal curves’ defined by the improper Poisson line process, and establish results which produce a framework for effective simulation from this distribution up to an L1 error which tends to 0 with increasing computational effort.

Return to the Poissonian city

Consider the following random spatial network: in a large disk, construct a network using a stationary and isotropic Poisson line process of unit intensity. Connect pairs of points using the network, with initial/final segments of the connecting path formed by travelling off the network in the opposite direction to that of the destination/source. Suppose further that connections are established using ‘near geodesics’, constructed between pairs of points using the perimeter of the cell containing these two points and formed using only the Poisson lines not separating them. If each pair of points generates an infinitesimal amount of traffic divided equally between the two connecting near geodesics, and if the Poisson line pattern is conditioned to contain a line through the centre, then what can be said about the total flow through the centre? In Kendall (2011) it was shown that a scaled version of this flow has asymptotic distribution given by the 4-volume of a region in 4-space, constructed using an improper anisotropic Poisson line process in an infinite planar strip. Here we construct a more amenable representation in terms of two ‘seminal curves’ defined by the improper Poisson line process, and establish results which produce a framework for effective simulation from this distribution up to anL1error which tends to 0 with increasing computational effort.

Extracting cutter/workpiece engagements in five-axis milling using solid modeler

Predicting cutting forces in milling process simulation requires finding cutter/workpiece engagements (CWEs). The calculation of these engagements is challenging due to the complicated and changing intersection geometry between the cutter and the in-process workpiece. In this paper, a solid modeling based methodology for finding CWEs generated in five-axis milling of free form surfaces is presented. The proposed methodology is an extension of the solid modeler based three-axis CWE extraction method given in [21]. At any given instant of the five-axis tool motion, the velocity vectors along the cutter axis may move in directions that do not lie in the same plane, and therefore the cutter envelopes need to be approximated by spline surfaces. Considering the spline surface approximations, the CWE methodology described in [21] does not work properly for the five-axis milling. Therefore in the proposed method, the in-process workpiece is used instead of the removal volume for extracting the CWEs. A terminology the feasible contact surfaces (FCS), defined by the envelope boundaries, is introduced. To extract the CWEs at a given cutter location, first the BODY entity, obtained by offsetting the FCS with an infinitesimal amount, is intersected with the in-process workpiece. Then, the resultant removal volume is decomposed into faces. Finally, the surface/surface intersections are performed between those faces and the FCS to obtain the CWE boundaries. To be used in the force model, the CWE boundaries are mapped from Euclidean 3D space to a parametric space defined by the engagement angle and the depth-of-cut for a given tool geometry.

Selfish Altruism, Fierce Cooperation and the Emergence of Cooperative Equilibria from Passing and Shooting

There is continuing debate about what explains cooperation and self-sacrifice in nature and in particular in humans. This paper suggests a new way to think about this famous problem. I argue that, for an evolutionary biologist as well as a quantitative social scientist, the triangle of two players in the presence of a predator (passing and shooting in 2-on-1 situations) is a fundamental conceptual building-block for understanding these phenomena. I show how, in the presence of a predator, cooperative equilibria rationally emerge among entirely selfish agents. If we examine the dynamics of such a model, and bias the lead player (ball possessor with pass/shoot i.e. cooperate/defect dilemma) in the selfish direction by only an infinitesimal amount, then, remarkably, the trajectories of the new system move towards a cooperative equilibrium. I argue that predators are common in the biological jungle but also in everyday human settings. Intuitively, this paper builds on the simple idea – a familiar one to a biologist observing the natural world but perhaps less so to social scientists – that everybody has enemies. As a technical contribution, I solve these models analytically in the unbiased case and numerically by an O(h5) approximation with the Runge-Kutta method.

First steps on asynchronous lattice-gas models with an application to a swarming rule

Lattice-gas cellular automata are often considered as a particular case of cellular automata in which additional constraints apply, such as conservation of particles or spatial exclusion. But what about their updating? How to deal with non-perfect synchrony? Novel definitions of asynchronism are proposed that respect the specific hypotheses of lattice-gas models. These definitions are then applied to a swarming rule in order to explore the robustness of the global emergent behaviour. In particular, we compare the synchronous and asynchronous case, and remark that a paradoxical phenomenon, the anti-alignment of particles, is no longer observed when a small but not infinitesimal amount of asynchronism is added.

Tecnología educativa: evolución y retos

Las actividades cotidianas, industriales, comerciales, administrativas, gubernamentales, de investigación, de formación y de muy diversas índoles han recurrido a una computadora como un medio para facilitar los procesos, mejorar los controles, tomar decisiones, realizar predicciones, étc. La educación, la formación académica, no ha quedado al margen de esta aparición que realizan las computadoras en las instituciones académicas, desde sus inicios en 1960 hasta nuestros días, sus aplicaciones en el aula ha ido evolucionando, modificando tanto los aspectos metodológicos del proceso de enseñanza - aprendizaje, de formación docente, es decir de las habilidades que se les demanda a los docentes para su uso y aprovechamiento en los ambientes de aprendizaje, garantizando un aumento en los aprendizajes significativos de los estudiantes.La llegada del internet, supone un "re-evolución" de la presencia de los equipos de cómputo con aplicaciones locales a espacios virtuales de aprendizaje, comunidades, acceso a recursos, disponibles en cantidad infinitesimal, algunos mejores que otros, pero sin duda alguna, un universo de información, es labor del docente navegar en este mar de información, para obtener aquellos recursos que puede llevar al aula a fin de propiciar aprendizajes significativos en los estudiantes, adicionalmente, como ciudadanos digitales tenemos la obligación moral de contribuir, de aportar, más y mejores recursos, con la finalidad de seguir fortaleciendo esta aldea digital en la que todos estamos inmersos.

국내 염전에서 생산된 갯벌천일염, 함수 및 해수의 가소제(DEHP) 오염 수준 평가

전국 25개 지역 염전에서 생산된 갯벌천일염 뿐만 아니라 천일염을 결정하는 함수 및 근원이 되는 염전 저수지 해수를 채취하여 가소제 오염수준을 평가하고, 갯벌천일염 및 염전 결정지 PVC 사용연수에 따른 환경호르몬의 상관관계를 분석하였다. 천일염의 DEP는 불검출에서 1.55 ppb 수준을 나타내었으며, DIBP는 불검출에서 2.38 ppb, DBP는 불검출에서 4.90 ppb, DEHA는 불검출에서 2.32 ppb 수준으로 검출되었으며, BBP는 불검출에서 1.45 ppb 수준으로 무시할 정도의 수준이었다. 천일염을 생산하는 염전에서 결정지 바닥재로 PVC 장판을 사용하면서 최근 가장 문제가 되고 있는 DEHP는 천일염을 생산하는 지역에 따라 불검출에서 268.5 ppb 수준으로 검출되었으며, 이러한 결과는 천일염에 0.268 ppm 포함되어 있는 것으로, 인체 안전성을 우려할만한 수준은 아닌 것으로 나타났다. 또한 DMP, DPrP, DNPP, DNHP, DCHP는 모든 시료에서 불검출 되었다. 전국 염전 저수지 해수 및 함수에 포함된 프탈레이트는 무시할 정도의 수준이었으며, 염전 저수지 해수에 대한 DEHP는 불검출에서 3.4 ppb 수준, 함수는 불검출에서 21.4 ppb 수준을 나타내어 불검출 수준이었다. 또한 염전 결정지 PVC 장판 사용기간에 따른 환경호르몬(DEHP) 오염여부가 의심됨에 따라 장판 사용 년수와 천일염에서 검출된 DEHP와의 관계를 분석한 결과 r=0.0362의 낮은 상관계수를 나타내었다.

Green Communications : réseaux low cost très économes en énergie et de haute qualité de service

Green Communications technology offers the possibility for an operator, an integrator or a site owner to install networks at extremely low cost and consume an infinitesimal amount of energy compared to existing networks. The technology ensures high quality of service by deploying intelligent routing and uses the widest paths to route the information from source to destination.

Overall composition dependences of coherent equilibria

The criterion for coherent equilibria is investigated. The expressions of driving force considering elastic energy for further formation of infinitesimal amount of one phase from the other in the two-phase coherent system are obtained. Zero driving force is shown to be a useful thermodynamic criterion for coherent equilibria, which not only has a clear physical meaning, but also is really convenient in coherent equilibria calculations. The coherent equilibrium equations are derived to directly demonstrate that the equilibrium compositions of phases in coherent equilibria depend on the overall alloy composition. In particular, the influence of the deviation of lattice parameter from Vegard’s law on the coherent spinodal, the field lines and the equilibrium compositions of coherent miscibility gap is examined in a regular binary solution. The calculated results show that even small deviation of lattice parameter from Vegard’s law can make the equilibrium compositions strongly dependent on the overall alloy composition. Therefore, the deviation of lattice parameter from Vegard’s law should be carefully considered in the calculation of coherent phase diagrams of the realistic systems.

On the Effect of Weak Magnetic Field on Solutions of Glutamic Acid: the Function of Water

Even though a wide literature is available on the effects of weak Extremely Low Frequency ElectroMagnetic Fields (ELF-EMF) on the biochemical reactions, nevertheless the physical nature of these effects is largely unknown. The main challenge is the mismatch between the infinitesimal amount of the energy carried by the perturbation and the entity of the response of the system. More than 10 years ago, it was claimed that a weak current can be induced in a aqueous solution of Glutamic acid exposed to a weak magnetic field having a certain frequency. We have checked the influence of ELF-EMF on Glutamic acid using the FTIR-ATR spectroscopy in order to observe structural changes induced by the exposure. Samples have been exposed for 10, 20 or 30 minutes to a magnetic field generated by Helmoltz coils and then placed into the spectrometer. After the exposure solutions having different pH values always shown a shift toward the de-protonated species. The effect lasts for minutes after the exposure before the native configuration is restored.

Erratum for “Suppression of Micro‐Vibrations of Low Earth Orbit Satellites with Flexible Solar Panels” by Khalid A. Al‐Saif and Mosaad A. Foda

Three axis-control low-earth-orbit (LEO) satellites use momentum exchange devices, such as reaction wheels, to maneuver and control their attitude to perform image acquisition. High-resolution satellite payloads demand stable pointing with very small jitter to achieve good performance. Microsatellites with flexible appendages such as deployable solar panels are very prone to vibration, especially when excited by internal actuators such as reaction wheels or momentum wheels that are used to control the attitude of the satellite. Any infinitesimal amount of unbalance in the reaction wheels’ rotors will impose a harmonic excitation that may interact with the structure of the solar panels. Therefore, controlling the solar panels’ structural vibration interaction would control the jitter. This control was achieved by attaching a set of properly chosen point masses at selected locations along the solar panels. The panels are modeled using Timoshenko beam theory. A scheme was proposed for choosing the optimal values of the added masses and their locations to minimize the satellite vibration. A prototype of a microsatellite with three reaction wheels and two solar panels, equipped with linear actuators to control the point mass location along the panels, is developed to demonstrate the concept.

Suppression of Microvibrations of Low-Earth-Orbit Satellites with Flexible Solar Panels

Three axis-control low-earth-orbit (LEO) satellites use momentum exchange devices, such as reaction wheels, to maneuver and control their attitude to perform image acquisition. High-resolution satellite payloads demand stable pointing with very small jitter to achieve good performance. Microsatellites with flexible appendages such as deployable solar panels are very prone to vibration, especially when excited by internal actuators such as reaction wheels or momentum wheels that are used to control the attitude of the satellite. Any infinitesimal amount of unbalance in the reaction wheels’ rotors will impose a harmonic excitation that may interact with the structure of the solar panels. Therefore, controlling the solar panels’ structural vibration interaction would control the jitter. This control was achieved by attaching a set of properly chosen point masses at selected locations along the solar panels. The panels are modeled using Timoshenko beam theory. A scheme was proposed for choosing the optimal va...

Diffusion-Limited Reactions in Crowded Environments

Diffusion-limited reactions are usually described within the Smoluchowski theory, which neglects interparticle interactions. We propose a simple way to incorporate excluded-volume effects building on simulations of hard sphere in the presence of a sink. For large values of the sink-to-particle size ratio R(s), the measured encounter rate is in good agreement with a simple generalization of the Smoluchowski equation at high densities. Reducing R(s), the encounter rate is substantially depressed and becomes even nonmonotonic for R(s)<<1. Concurrently with the saturation of the rate, stationary density waves set in close to the sink. A mean-field analysis helps to shed light on the subtle link between such ordering and the slowing down of the encounter dynamics. Finally, we show how an infinitesimal amount of nonreacting impurities can equally slow down dramatically the reaction.

Selectivities in Partial Hydrogenation

Journal of the American Oil Chemists' SocietyVolume 87, Issue 1 p. 115-117 Letter to the Editor Selectivities in Partial Hydrogenation Albert J. Dijkstra, Corresponding Author Albert J. Dijkstra albert@dijkstra-tucker.be +33-5-53491214 Carbougnères, St Eutrope-de-Born, 47210 Francealbert@dijkstra-tucker.beSearch for more papers by this author Albert J. Dijkstra, Corresponding Author Albert J. Dijkstra albert@dijkstra-tucker.be +33-5-53491214 Carbougnères, St Eutrope-de-Born, 47210 Francealbert@dijkstra-tucker.beSearch for more papers by this author First published: 17 November 2009 https://doi.org/10.1007/s11746-009-1507-zCitations: 6Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume87, Issue1January 2010Pages 115-117 RelatedInformation

Diffusive limits for the Knudsen gas in a thin channel with accommodation on the boundary

We consider a model for a free molecular flow in a thin channel bounded by two parallel plates on which Maxwellian boundary conditions with (fixed) accommodation and a generic scattering kernel apply. Using functional analytic tools, we show that as the width of the channel vanishes, and on a suitable temporal scale, the evolution of the density is described by a diffusion problem. We distinguish two classes of temporal scalings (normal and anomalous) and we show that an infinitesimal amount of grazing collisions with the walls of the channel is responsible for the anomalous diffusion. The method employed is adapted from the original work of F. Golse in Asymptot. Anal. 17 (1998), 1-12.

Adaptive routing with stale information

We investigate the behaviour of load-adaptive rerouting policies in the Wardrop model where decisions must be made on the basis of stale information. In this model, each one of an infinite number of agents controls an infinitesimal amount of flow, thus contributing to a network flow which induces latency. In our dynamic extension of this model, agents are activated in a concurrent and asynchronous fashion and may reroute their flow with the aim of reducing their sustained latency. It is a well-known problem that in settings where latency information is not always up-to-date, such behaviour may lead to oscillation effects which seriously harm network performance. Two quantities determine the difficulty of avoiding oscillation: the steepness of the latency functions and the maximum possible age of the information T.In this work we ask for conditions that the rerouting policies must adhere to in order to converge to an equilibrium despite the information being stale. We consider simple policies which sample another path in a first step and then migrate from the current path to the new one with a probability that is a function of the anticipated latency gain. In fact we can show that our class of policies guarantees convergence if the latter migration probability function satisfies a certain smoothness condition that resembles Lipschitz continuity. It turns out that for smooth adaptation policies where the migration probability is chosen small enough relative to the inverse of the steepness of the latency functions and T, the population actually converges to an equilibrium.In addition, we analyse the speed of convergence towards approximate equilibria of two specific variants of smooth adaptive routing policies, e.g., for a replication policy adopted from evolutionary game theory.