Low mobility materials and Debye dielectric loss due to electrons

It is shown that substances which exhibit Debye type of dielectric loss due to electrons in the bulk also show very low electronic mobility. Measurements are suggested to confirm this. Relevant substances are ionic crystals with positive ions of high charge, such as oxides, and possibly certain molecular solids. In substances of the above type the band model has broken down. Relevant theoretical methods are outlined, using electron wave functions centered on the positive ions, rather than (as in previously developed methods) on their lattice sites. The perturbation giving rise to transitions between these localized states is composed of four terms, each a different kind of average of the electron-lattice interaction. One of these terms explicitly contains the effect of the localized electron on the phonon spectrum.     

Remotely controlled electro-responsive on-demand nanotherapy based on amine-modified graphene oxide for synergistic dual drug delivery

This study focuses on the development of a new electric field responsive graphene oxide (GO) nanoparticle system for on-demand drug delivery. Today, GO is an attractive option adopted in various biological applications for its exclusive features such as flexibility, conductiveness, cost-effectiveness, and external stimuli-responsive nature. It is usual to utilize multiple drugs in cancer treatment. This kind of therapy has lesser side-effects, drug resistance, and is more effective than utilizing only one drug. This study aims to determine low-voltage-controlled dual drug (aspirin and doxorubicin) release from GO surface. Here, we have demonstrated how to control the drug release rate remotely with a handy mobile phone, with zero passive release at idle time. In addition, the study focused to estimate the synergism of aspirin with doxorubicin in the release mechanism from GO in the presence of external voltage, using the spectroscopic method. Moreover, we observed aspirin- and doxorubicin-induced synergistic antitumor activity in MDA-MB 231 (breast cancer cell) in vitro. Thus, our study presents a noble combination of aspirin and doxorubicin that could be utilized for remotely controlled on-demand drug delivery for triple negative breast cancer treatment, using GO as a carrier.     

Asymmetric Synthesis of Bicyclic Pyrazolidinones through Alkaloid-Catalyzed [3+2]-Cycloadditions of Ketenes and Azomethine Imines

A versatile asymmetric synthesis of bicyclic pyrazolidinones through alkaloid-catalyzed formal [3+2]- and [3+2+2]-cycloadditions of ketenes with azomethine imines is described. The methodology was found to be tolerant of ketene and a variety of monosubstituted ketenes (R=alkyl, OAc). The products were formed in good to excellent yields (71–99 % for 24 examples, 39 examples in all), with good to excellent diastereoselectivity in many cases (dr 3 : 1 to 27 : 1 for 22 examples), and with excellent enantioselectivity for most examples (≥93 % ee for 34 products). In the case of most disubstituted ketenes, the reaction proceeded through a [3+2+2]-cycloaddition to form structurally interesting bicyclic pyrazolo-oxadiazepinediones with moderate diastereoselectivity (dr up to 3.7 : 1) and as racemic mixtures (3 examples). The method represents the first unambiguous example of an enantioselective reaction between ketenes and a 1,3-dipole.     

Novel approaches for portfolio construction using second order stochastic dominance

In the last decade, a few models of portfolio construction have been proposed which apply second order stochastic dominance (SSD) as a choice criterion. SSD approach requires the use of a reference distribution which acts as a benchmark. The return distribution of the computed portfolio dominates the benchmark by the SSD criterion. The benchmark distribution naturally plays an important role since different benchmarks lead to very different portfolio solutions. In this paper we describe a novel concept of reshaping the benchmark distribution with a view to obtaining portfolio solutions which have enhanced return distributions. The return distribution of the constructed portfolio is considered enhanced if the left tail is improved, the downside risk is reduced and the standard deviation remains within a specified range. We extend this approach from long only to long-short strategies which are used by many hedge fund and quant fund practitioners. We present computational results which illustrate (1) how this approach leads to superior portfolio performance (2) how significantly better performance is achieved for portfolios that include shorting of assets.     

Wing-type vortex generators for fin-and-tube heat exchangers

The effect of wing-type vortex generators on heat transfer and pressure drop of a fin-and-tube heat exchanger element was investigated. Local heat transfer was measured by liquid crystal thermography on the fin in the Reynolds number range of 600–2700. Flow losses were estimated from the measured pressure drop of an element. Delta winglets were used as vortex generators. Four fin-and-tube configurations were tested, an inline and a staggered arrangement, each with plain fins and with fins with a pair of vortex generators behind each tube. For the inline tube arrangement the vortex generators increase the heat transfer by 55–65% with a corresponding increase of 20–45% in the apparent friction factor. Results indicate that the vortex generators have the potential to reduce considerably the size and mass of heat exchangers for a given heat load.     

Einfluß ausgestanzter Deltaflügel-Wirbelerzeuger auf Wärmeübergang und Strömungswiderstand von Rippenrohren

Zusammenfassung Der Einfluß von Sekundärflächen in der Form eines Delta-Halbflügelpaares auf Wärmeübergang und Strömungs-widerstand einer Rippenrohr-Konfiguration wurde untersucht. Die Halbflügelflächen wurden aus der Rippe ausgestanzt, die Sehne der Halbflügel blieb mit der Rippe verbunden. Die Flügelfläche war sehr klein gegenüber der Rippenfläche und bildete einen Winkel mit der Hauptströmungsrichtung, so daß die Vorderkanten starke Längswirbel erzeugten. Die Versuche wurden in einem geschlossenen Windkanal mit vertikaler Meßstrecke durchgeführt. Lokaler und mittlerer Wärmeübergang wurden durch instationäre Flüssigkristall-Thermografie bestimmt, die Widerstandsmessung erfolgte durch Wägung. Im Reynoldszahlbereich 2000 bis 5300 wurde die optimale Lage des Halbflügelpaares relativ zum Rohr ermittelt. Für ein Verhältnis der Fläche des Halbflügelpaares zur Rippenfläche von 0,003 wurden mittlere Wärmeübergangserhöhungen von 20% bei gleichzeitiger Widerstandsminderung der Rippenrohr-Konfiguration von 7% erzielt. Lokale Wärmeübergangserhöhungen von mehr als 70% wurden gemessen. Aus den Messungen folgt, daß Delta-Halbflügel den Wärmeübergang von Rippenrohr-Konfigurationen erhöhen und gleichzeitig den Strömungsverlust senken können.

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Influence of punched-out delta-winglet vortex generators on heat transfer and drag of fin-tubes

Fin-tube configurations with a small delta-winglet pair punched out from the fins have been investigated with regard to heat transfer and drag. The winglets were punched out in such a way that their chords stayed connected with the fin. The winglet area was small compared to the fin area, it formed an angle with the main flow direction, so that the leading edges generated strong longitudinal vortices. The experiments were performed in a wind tunnel with vertical test section. Local and global heat transfer were determined by liquid crystal thermography, drag was measured by a scale. For Reynolds numbers between 2000 and 5300 the optimal winglet position relative to the tube was determined. For a winglet to fin area ratio of 0.003 an overall heat transfer enhancement on the fin of 20% resulted with a simultaneous drag reduction of 7%. Local heat transfer enhancements of more than 70% were measured. From the measurements follows that winglet pairs can increase the heat transfer in fin-tube configurations while simultaneously decreasing the flow losses.

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Herrn Prof. Klaus Gersten zum 60. Geburtstag gewidmet     

Meromorphic tensor equivalence for Yangians and quantum loop algebras

Let \(\mathfrak{g}\) be a complex semisimple Lie algebra, and \(Y_{\hbar }(\mathfrak{g})\), \(U_{q}(L\mathfrak{g})\) the corresponding Yangian and quantum loop algebra, with deformation parameters related by \(q=e^{\pi \iota \hbar }\). When \(\hbar \) is not a rational number, we constructed in Gautam and Toledano Laredo (J. Am. Math. Soc. 29:775, 2016) a faithful functor \(\Gamma \) from the category of finite-dimensional representations of \(Y_{\hbar }(\mathfrak{g})\) to those of \(U_{q}(L \mathfrak{g})\). The functor \(\Gamma \) is governed by the additive difference equations defined by the commuting fields of the Yangian, and restricts to an equivalence on a subcategory of \(\operatorname{Rep}_{\operatorname{fd}}(Y_{\hbar }(\mathfrak{g}))\) defined by choosing a branch of the logarithm. In this paper, we construct a tensor structure on \(\Gamma \) and show that, if \(|q|\neq 1\), it yields an equivalence of meromorphic braided tensor categories, when \(Y_{\hbar }(\mathfrak{g})\) and \(U_{q}(L\mathfrak{g})\) are endowed with the deformed Drinfeld coproducts and the commutative part of their universal \(R\)-matrices. This proves in particular the Kohno–Drinfeld theorem for the abelian \(q\)KZ equations defined by \(Y_{\hbar }(\mathfrak{g})\). The tensor structure arises from the abelian \(q\)KZ equations defined by an appropriate regularisation of the commutative part of the \(R\)-matrix of \(Y_{\hbar }(\mathfrak{g})\).     

Interior local null controllability of one‐dimensional compressible flow near a constant steady state

We consider the one‐dimensional compressible Navier–Stokes equations with periodic boundary conditions, with initial conditions in a small neighborhood of a state of uniform density and uniform nonzero velocity. We prove that, with a control given only by a body force localized in a subinterval, we can steer the system to uniform density and velocity. Copyright © 2016 John Wiley & Sons, Ltd.     

Droplet transport and coalescence kinetics in emulsions subjected to acoustic fields

A method to aid the separation of the oil phase from aqueous emulsions using a low-intensity, resonant ultrasonic field has recently been developed. The density and compressibility difference between the dispersed and continuous phases within the emulsion results in a net force on the oil drops that pushes them toward the pressure antinodes of the standing-wave field, where coalescence subsequently occurs. A trajectory model is developed to predict the relative motion of drops subjected to the acoustic field. Such trajectories are sensitive to the physical properties and relative size of interacting drops, the initial configuration of the drops, and acoustic field parameters. Model predictions are validated by comparing experimentally observed trajectories with those predicted by the model. The modeling approach is then extended to determine the temporal evolution of the size of the region surrounding a target drop cleared by coalescence as a function of physical and acoustic field parameters. These results form the basis of a population balance model that attempts to track the size-evolution of a drop population coalescing under the influence of an acoustic field.     

Radioactive ion beam post-acceleration at ISAC

ISAC at TRIUMF is a world-class facility for the production and post-acceleration of radioactive ion beams (RIB). Commissioned in 2002 the ISAC I linear accelerator serves three different beam lines delivering both stable and radioactive species. Two of them are permanent experiments (DRAGON and TUDA); the third one is a general purpose station (GPS). The maximum energy we can reach in ISAC I is 1.8 MeV/u. ISAC II is a phased upgrade of the ISAC facility. The beam coming from ISAC I is injected at 1.5 MeV/u into a new superconducting LINAC. In `Phase I' the LINAC adds 20 MV to the beam energy and 20 MV more will be added in `Phase II'. The paper will give an overview of both the ISAC I and ISAC II accelerators. Operational experience with accelerating RIBs in ISAC I is summarized. First ISAC II commissioning results are presented.