The effect of a concentration-dependent viscosity on\ud particle transport in a channel flow with porous walls

We analyse the transport of a dilute suspension of particles through a channel with porous walls accounting for the concentration dependence of the viscosity. Two cases of leakage flow of fluid through the porous channel walls are studied: (i) constant flux, and (ii) dependent on the pressure drop across the wall. The effect of mixing the suspension first compared with point injection is examined by considering inlet concentration distributions of different widths. We find that a pessimal distribution width exists that maximizes the required hydrodynamic pressure for a constant fluid influx. We also show that the presence of an osmotic pressure may lead to fluid being sucked into the channel. We consider how the application of an external hydrodynamic pressure affects this observation and discuss the significance of our results for water filtration

Combined treatment of biomatrices with nisin and pulsed electric fields as a potential decontamination method?

Pulsed electric field (PEF) treatment has been shown to achieve bacterial inactivation in collagen gels whilst retaining the ability of the collagen to function as a biomaterial [1, 2]. Nisin, an antimicrobial peptide, has been used widely as a food preservative and has shown bactericidal action against a number of Gram-positive bacteria [3]. The potential of nisin to increase the efficacy of PEF disinfection of collagen gels to be used for tissue engineering applications was investigated

Interleukin-1©¬ (IL-1©¬), IL-1 receptor antagonist, and TNF¥á production in whole blood

Contains fulltext : 4746.pdf (publisher's version ) (Open Access

Boson gas in a periodic array of tubes

We report the thermodynamic properties of an ideal boson gas confined in an infinite periodic array of channels modeled by two, mutually perpendicular, Kronig-Penney delta-potentials. The particle's motion is hindered in the x-y directions, allowing tunneling of particles through the walls, while no confinement along the z direction is considered. It is shown that there exists a finite Bose- Einstein condensation (BEC) critical temperature Tc that decreases monotonically from the 3D ideal boson gas (IBG) value $T_{0}$ as the strength of confinement $P_{0}$ is increased while keeping the channel's cross section, $a_{x}a_{y}$ constant. In contrast, Tc is a non-monotonic function of the cross-section area for fixed $P_{0}$. In addition to the BEC cusp, the specific heat exhibits a set of maxima and minima. The minimum located at the highest temperature is a clear signal of the confinement effect which occurs when the boson wavelength is twice the cross-section side size. This confinement is amplified when the wall strength is increased until a dimensional crossover from 3D to 1D is produced. Some of these features in the specific heat obtained from this simple model can be related, qualitatively, to at least two different experimental situations: $^4$He adsorbed within the interstitial channels of a bundle of carbon nanotubes and superconductor-multistrand-wires Nb$_{3}$Sn.Comment: 9 pages, 10 figures, submitte

Optimal designs for rational function regression

We consider optimal non-sequential designs for a large class of (linear and nonlinear) regression models involving polynomials and rational functions with heteroscedastic noise also given by a polynomial or rational weight function. The proposed method treats D-, E-, A-, and $\Phi_p$-optimal designs in a unified manner, and generates a polynomial whose zeros are the support points of the optimal approximate design, generalizing a number of previously known results of the same flavor. The method is based on a mathematical optimization model that can incorporate various criteria of optimality and can be solved efficiently by well established numerical optimization methods. In contrast to previous optimization-based methods proposed for similar design problems, it also has theoretical guarantee of its algorithmic efficiency; in fact, the running times of all numerical examples considered in the paper are negligible. The stability of the method is demonstrated in an example involving high degree polynomials. After discussing linear models, applications for finding locally optimal designs for nonlinear regression models involving rational functions are presented, then extensions to robust regression designs, and trigonometric regression are shown. As a corollary, an upper bound on the size of the support set of the minimally-supported optimal designs is also found. The method is of considerable practical importance, with the potential for instance to impact design software development. Further study of the optimality conditions of the main optimization model might also yield new theoretical insights.Comment: 25 pages. Previous version updated with more details in the theory and additional example

T-Duality and Penrose limits of spatially homogeneous and inhomogeneous cosmologies

Penrose limits of inhomogeneous cosmologies admitting two abelian Killing vectors and their abelian T-duals are found in general. The wave profiles of the resulting plane waves are given for particular solutions. Abelian and non-abelian T-duality are used as solution generating techniques. Furthermore, it is found that unlike in the case of abelian T-duality, non-abelian T-duality and taking the Penrose limit are not commutative procedures.Comment: 16 pages, 4 figures. Discussion on non-abelian T-duality expande

Amine-modified polyionic liquid supports enhance the efficacy of PdNPs for the catalytic hydrogenation of CO₂ to formate

Palladium nanoparticles stabilised by aniline modified polymer immobilised ionic liquid is a remarkably active catalyst for the hydrogenation of CO₂ to formate; the initial TOF of 500 h⁻¹ is markedly higher than either unmodified catalyst or its benzylamine and N,N-dimethylaniline modified counterparts and is among the highest to be reported for a PdNP-based catalyst

Quantum Griffiths effects and smeared phase transitions in metals: theory and experiment

In this paper, we review theoretical and experimental research on rare region effects at quantum phase transitions in disordered itinerant electron systems. After summarizing a few basic concepts about phase transitions in the presence of quenched randomness, we introduce the idea of rare regions and discuss their importance. We then analyze in detail the different phenomena that can arise at magnetic quantum phase transitions in disordered metals, including quantum Griffiths singularities, smeared phase transitions, and cluster-glass formation. For each scenario, we discuss the resulting phase diagram and summarize the behavior of various observables. We then review several recent experiments that provide examples of these rare region phenomena. We conclude by discussing limitations of current approaches and open questions.Comment: 31 pages, 7 eps figures included, v2: discussion of the dissipative Ising chain fixed, references added, v3: final version as publishe

Selective Partial Reduction of Nitroarenes to the Hydrazoarene Catalyzed by Amine‐Modified Ordered Mesoporous Silica Immobilized Ionic Liquid (OMSIIL) Stabilised RuNPs

Ruthenium nanoparticles stabilised by an amine-modified Ordered Mesoporous Silica Immobilized Ionic Liquid (OMSIIL) are efficient catalysts for the partial reduction of nitrobenzene to hydrazobenzene with 100 % selectivity as well as the complete reduction to aniline. High selectivity for the partial reduction of nitrobenzene to hydrazobenzene was obtained when the reaction was conducted in ethanol with 0.5 mol% catalyst and NaBH₄ as the hydrogen donor whereas aniline was obtained as the sole product in water when dimethylamine borane (DMAB) was used as the hydrogen donor. Interestingly, while a range of electron poor nitroarenes were reduced to the corresponding hydrazoarene with high selectivities and good conversions, nitroarenes substituted with electron donating groups resulted in complete reduction to the aniline. Composition-time profiles suggest that reductions conducted in ethanol with sodium borohydride occur via the condensation pathway while those conducted in water using dimethylamine borane as the hydrogen source may well go via the direct pathway. This is the first example of the selective reduction of nitrobenzene to hydrazobenzene using a ruthenium nanoparticle-based catalyst and the initial TOF of 320 mol nitrobenzene converted mol Ru⁻¹ h⁻¹ for the partial reduction of nitrobenzene to hydrazobenzene is markedly higher than previous literature reports. A study of the catalyst performance as a function of the surface modification revealed that each component has a direct and dramatic effect on the efficacy as RuNPs stabilised by COK-12 modified with imidazolium-based ionic liquid and a primary amine gave the highest conversion while selective removal of either component or replacement of the primary amine with a tertiary amine resulted in a marked reduction in efficiency