Royal Soc Research Articles

Structural Aspects of Materials in Optimization of Fuel Cell Electrodes.

Today's energy problems, caused by the irrational consumption of fossil fuels and, as a result, terrible environmental consequences, require the global population to quickly introduce clean energy sources. Electrochemical power sources, which include the fuel cell, provide the technological basis for electrical energy production. While proton exchange membrane fuel cells (PEMFC) rely on platinum based catalysts, obtaining stable and earth abundant catalytic materials for the oxygen reduction reaction (ORR) is an important step towards large scale integration. Our work focusses on FeNC noble-metal free catalysts in PEMFC conditions. The reaction conditions are much more complex in comparison to half cells, as transport processes and e.g. carbon oxidation affect the performance data. Thus, it turns out to be extremely difficult to determine the most important factors affecting the catalytic activity and stability of the material and to optimize the structure of the membrane-electrode assembly as several factors are overlaying each other: For example, the pyrolysis temperature affects the surface area, degree of graphitization and iron-related composition as well as extent of surface functional groups [1]. The metal loading, pyrolysis temperature and a use of possible precursor templates effects the structure, surface area as well as ORR activity and selectivity of catalysts [2], [3].In our recent work, it was shown that in contrast to the electrochemical characteristics observed in rotating disc electrode (RDE) measurements, the best performing catalyst was prepared at the highest investigated temperature for both FC activity and stability [1]. In contrast, the dwell time had only a limited impact at low pyrolysis temperature, whereas a variation from 30 min to 90 min gave significant destruction of molecular FeNx moieties for the high temperature pyrolysis. [1]To gain further insights on the effect of preparation parameters on FC performance and in specific stability, we coupled a quadrupole mas-spectrometer to the cathode exhaust to follow possible release of CO2 depending on the applied conditions. The data are interpreted together with the structural characterization of the materials. We will discuss how the dwell time and pyrolysis temperature effected on morphology changes of the catalyst and to what extent this impacts the FC activity and short-term stability.AcknowledgementsA.O. would like to thank you the TU Darmstadt for the Future talent scholarship, UIK gratefully acknowledges financial support by the BMBF young research group StRedO (03XP0092), and we thank Y. Ostroverkh, and Z. L. Müller, for the consultation and assistance with the fuel cell setup.[1] J. Scharf, M. Kübler, V. Gridin, W.D.Z. Wallace, L. Ni, S.D. Paul, U.I. Kramm, Relation between half-cell and fuel cell activity and stability of FeNC catalysts for the oxygen reduction reaction, (2022) SusMat, accepted (doi: 10.1002/sus2.84).[2] P.Theis, W.D. Z. Wallace, L. Ni, M. Kübler, A. Schlander, R. W. Stark, N. Weidler, M, Gallei, U. I. Kramm. Systematic study of precursor effects on structure and oxygen reaction activity of FeNC catalysts, (2021) Philos. Trans. Royal Soc. A PHILOS T R SOC A, (doi: 10.6084/m9.figshare.c.5506708).[3] P. Boldrin, D. Malko, A. Mehmood, U. I. Kramm, S. Wagner, S. Paul, N. Weidler, A. Kucernak. Deactivation, reactivation and super-activation of Fe-N/C oxygen reduction electrocatalysts: Gas sorption, physical and electrochemical investigation using NO and O2., (2021) Appl. Catal. B, Vol. 292, 120169, (doi: 10.1016/j.apcatb.2021.120169).

Practical Implementation of Encoding Range Top-2 Queries

Abstract We design a practical variant of an encoding for range Top-2 query (RT2Q) and evaluate its performance. Given an array $A[1,n]$ of $n$ elements from a total order, the range Top-2 encoding problem is to construct a data structure that answers ${\textsf{RT2Q}}{}$, which returns the positions of the first and second largest elements within a given range of $A$, without accessing the array $A$ at query time. We design the following two implementations: (i) an implementation based on an alternative representation of Davoodi et al.’s [Phil. Trans. Royal Soc. A, 2016] data structure, which supports queries efficiently. Experimental results show that our implementation is efficient in practice and gives improved time-space trade-offs compared with the indexing data structures (which keep the original array $A$ as part of the data structure) for range maximum queries. (ii) Another implementation based on Jo et al.’s ${\textsf{RT2Q}}{}$ encoding on $2 \times n$ array [CPM, 2016], which can be constructed in $O(n)$ time. We compare our encoding with Gawrychowski and Nicholson’s optimal encoding [ICALP, 2015] and show that in most cases, our encoding shows faster construction time while using a competitive space in practice.

Locomotion with a wavy cylindrical filament in a yield-stress fluid

A yield stress is added to Taylor's (1952, Proc. Royal Soc. A, 211, 225-239) model of a microscopic organism with a wavy cylindrical tail swimming through a viscous fluid. Viscoplastic slender-body theory is employed for the task, generalising existing results for Bingham fluid to the Herschel–Bulkley constitutive model. Numerical solutions are provided over a range of the two key parameters of the problem: the wave amplitude relative to the wavelength, and a Bingham number which describes the strength of the yield stress. Numerical solutions are supplemented with discussions of various limits of the problem in which analytical progress is possible. If the wave amplitude is sufficiently small, the yield stress of the material inevitably dominates the flow; the resulting ‘plastic locomotion’ results in swimming speeds that depend strongly on the swimming gait, and can, in some cases, even be negative. Conversely, when the yield stress is large, swimming becomes possible at the wave speed, with the swimmer sliding or burrowing along its centreline with a relatively high efficiency.

Facilitators and barriers to living donor kidney transplantation

Facilitators and barriers to living donor kidney transplantation

A Multiscale Perspective on Misfit Dislocations in Oxide Films

Misfit dislocations were conceived by Jan H. van der Merwe in 1949 (Frank, F. C., and van der Merwe, J. H. (1949). One-dimensional dislocations. I and II. Proc. Royal Soc. London. Series A. 198, 205-216 and 216-225), long before they were directly observed by transmission electron microscopy in the early sixties (Matthews, J. W. (1961). The observation of dislocations to accommodate the misfit between crystals with different lattice parameters. Phil. Mag. 6, 1347-1349; Delavignette, P., Tournier, J., and Amelinckx, S. (1961). Direct observation of dislocations due to epitaxy. Phil. Mag. 6, 1419-1420). Since then, their appreciation by the scientific community has evolved from being considered a drawback to being recognized as a challenging opportunity. However, taking full advantage of all their potential, sets out issues that despite being well established in semiconductor or metals, remain poorly understood in transition metal oxides. In this Perspective contribution, we select recent findings on misfit dislocations in La0.7Sr0.3MnO3 under compressive strain, to illustrate effects spanning a range of length scales, like the coupling between strain and defect chemistry in and around their cores, the impact of kinetics on the morphology of dislocated films, or the subtle sensitivity of oxide properties to dislocation strain fields.

Characterization of power-law creep in the solid-acid CsHSO4 via nanoindentation

Abstract

Controlling land-based sources as a measure to reduce (micro)plastic contamination in coastal environments

Controlling land-based sources as a measure to reduce (micro)plastic contamination in coastal environments

In memoriam: Sir Peter Mansfield (1933–2017)

In memoriam: Sir Peter Mansfield (1933–2017)

COGNATE: comparative gene annotation characterizer

BackgroundThe comparison of gene and genome structures across species has the potential to reveal major trends of genome evolution. However, such a comparative approach is currently hampered by a lack of standardization (e.g., Elliott TA, Gregory TR, Philos Trans Royal Soc B: Biol Sci 370:20140331, 2015). For example, testing the hypothesis that the total amount of coding sequences is a reliable measure of potential proteome diversity (Wang M, Kurland CG, Caetano-Anollés G, PNAS 108:11954, 2011) requires the application of standardized definitions of coding sequence and genes to create both comparable and comprehensive data sets and corresponding summary statistics. However, such standard definitions either do not exist or are not consistently applied. These circumstances call for a standard at the descriptive level using a minimum of parameters as well as an undeviating use of standardized terms, and for software that infers the required data under these strict definitions. The acquisition of a comprehensive, descriptive, and standardized set of parameters and summary statistics for genome publications and further analyses can thus greatly benefit from the availability of an easy to use standard tool.ResultsWe developed a new open-source command-line tool, COGNATE (Comparative Gene Annotation Characterizer), which uses a given genome assembly and its annotation of protein-coding genes for a detailed description of the respective gene and genome structure parameters. Additionally, we revised the standard definitions of gene and genome structures and provide the definitions used by COGNATE as a working draft suggestion for further reference. Complete parameter lists and summary statistics are inferred using this set of definitions to allow down-stream analyses and to provide an overview of the genome and gene repertoire characteristics. COGNATE is written in Perl and freely available at the ZFMK homepage (https://www.zfmk.de/en/COGNATE) and on github (https://github.com/ZFMK/COGNATE).ConclusionThe tool COGNATE allows comparing genome assemblies and structural elements on multiples levels (e.g., scaffold or contig sequence, gene). It clearly enhances comparability between analyses. Thus, COGNATE can provide the important standardization of both genome and gene structure parameter disclosure as well as data acquisition for future comparative analyses. With the establishment of comprehensive descriptive standards and the extensive availability of genomes, an encompassing database will become possible.

Eczema and older people: introducing the TalkingEczema tool.

British Journal of Community NursingVol. 22, No. 2 CommentEczema and older people: introducing the TalkingEczema toolJulie Van OnselenJulie Van OnselenSearch for more papers by this authorJulie Van OnselenPublished Online:4 Feb 2017https://doi.org/10.12968/bjcn.2017.22.2.62AboutSectionsView articleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InEmail View article References All Party Parliamentary Group on Skin (2003) Report and enquiry into the impact of skin diseases on people's lives. APPGS: London Google ScholarBhatti ZU, Salek MS, Finlay AY (2011) Chronic diseases influence major life changing decisions: a new domain in quality of life research. J Royal Soc Med 104: 241–50 Crossref, Medline, Google ScholarCohen KR, Frank J, Salbu RL, Israel I (2012) Pruritus in the Elderly: Clinical Approaches to the Improvement of Quality of Life. Pharm Therapeutics J 374: 227–39 Google ScholarCork MJ, Danby S (2009) Skin barrier breakdown: a renaissance in emollient therapy. Br J Nurs 18(14): 872–7 Link, Google ScholarCork MJ, Robinson DA, Vasilopoulos Y (2009) Epidermal barrier dysfunction in atopic dermatitis. J Invest Dermatol 129: 1892–1908 Crossref, Medline, Google ScholarDanby SG, Brown K, Higgs-Bayliss T, Chittock J, Abenail L, Cork MJ (2016) The Effect of an Emollient Containing Urea, Ceramide NP, and Lactate on Skin Barrier Structure and Function in Older People with Dry Skin. Skin Pharmacol Physiol 29(3): 136–47 Crossref, Google ScholarDeo MS, Kerse N, Vandai AC, Jarrett P (2015) Dermatological disease in the older age group: a cross-sectional study in aged care facilities. BMJ Open 5: e009941 doi: 10.1136/bmjopen-2015-009941 Crossref, Google ScholarIngram J (2016) Eczematous disorders. In: Griffiths CBarker JBlekier TChalmers RCreamer D (eds) Rook's Textbook of Dermatology 39: 1–31 Google ScholarKatasarou A, Armenaka M (2011) Atopic dermatitis in older patients: particular points. J Eur Acad Dermatol Venerol 25(1): 12–18 Crossref, Google ScholarMedicines and Healthcare products Regulatory Agency (2016) Paraffin-based skin emollients on dressings or clothing: fire risk. https://www.gov.uk/drug-safety-update/paraffin-based-skin-emollients-on-dressings-or-clothing-fire-risk (accessed 1 December 2016) Google ScholarNemoto-Hasebe I, Akiyama M, Nomura T, Sandilands A, McLean WH, Shimizu H (2009) Clinical severity correlates with impaired barrier in filaggrin-related eczema. J Invest Dermatol 129(3): 682–9 Crossref, Medline, Google ScholarYachin B, Tamar E, Toy GG, Oztas P, Hayran M, Ali N (2006) The prevalence of skin diseases in the elderly: analysis of 4099 geriatric patients. Int J Dermatol 45(6): 672–6 Crossref, Medline, Google ScholarZirwas MJ, Holder JL (2009) Patient education Strategies in Dermatology. J Clin Aesthetic Dermatol 2(12): 28–34 Medline, Google Scholar FiguresReferencesRelatedDetailsCited byEczematous conditions in the older personLesley Butcher19 November 2018 | Nursing and Residential Care, Vol. 20, No. 12Eczematous conditions in the older personLesley Butcher31 July 2018 | British Journal of Community Nursing, Vol. 23, No. 8Providing care for people living with dermatitis and dementiaLesley Butcher11 January 2018 | Nursing and Residential Care, Vol. 20, No. 1 2 February 2017Volume 22Issue 2ISSN (print): 1462-4753ISSN (online): 2052-2215 Metrics History Published online 4 February 2017 Published in print 2 February 2017 Information© MA Healthcare LimitedPDF download

Towards an Automatic Super-Resolution Image Based Method for Current 2-Dimensional Contrast Enhanced Ultrasound

This study aims to create a new automatic super-resolution image based method to be used with current contrast enhanced ultrasound imaging (CEUS) technology without the need for the generation of new imaging modes. The emerging field of super-resolution ultrasound imaging aims to detect and track single microbubbles to provide image data that reveals the detail of the vascular treewith micrometre resolution. Current 2-dimensional (2D) ultrasound provides significant challenges as the point spread function (PSF) and the number of MBs are highly variable not only between different image frames but also throughout a single image. This high variability is related to the orders of magnitude difference in blood volume between the largest (arteries) and the smallest of vessels (capillaries). The original hypothesis of this study was that a super-resolution image based method can provide up to 10-fold resolution gains compared to conventional imaging using video loops that are short in duration and are generated with existing CEUS modes. For this a new super-resolution image based method was developed. The method is based on a morphological based algorithm designed forfluorescence optical microscopy and incorporates both particle detection and trajectory linking and is also capable of handling large particle numbers (Wilson et al. Royal Soc Open Sci 2016; 3: 160225). The study was designed to address the original hypothesis using an in vivo animal model. The ovaries from blackface ewes were exteriorised and the corpus luteum (CL) was imaged using CEUS. The CL is ideally suited for perfusion imaging studies as it is a highly angiogenic gland and has the size of a small solid tumour (Sboros et al. Ultrasound Med Biol 2011; 37: 59). Once the CEUS imaging was complete the CL was fixed for histological evaluation in order to identify large vessels and endothelium for comparison with the CEUS image data. An iU-22 Philips scanner with an L9-3 linear array probe (6MHz) was used to generate the CEUS images. Intravenous infusions of Sonovue MB suspensions generated images with high densities of single microbubbles. Video loops (typically 1 minute long) were collected. The image analysis method for generating the super-resolution data utilises 11 different parameters. Firstly, the method detects and localises microbubbles through the use of a particle probability image (PPI) which enhances their signal. The PPI is formed using non-local and statistical mapping of the original greyscale by measuring local contrast and particle size. In the second step microbubbles in consecutive frames are linked in order to generate their trajectories through the vascular bed. The nearest neighbour linking model used has been extended to include the morphology and intensity profiles of the microbubbles. The software is automatic in that after an initial manual training of the parameter set it is able to adapt to the image data. Several less than 1 minute long (less than 600 frames) video loops of CEUS image data from the CL were processed. The processing of each video loop using the method described above produces a particle/microbubble density and a velocity map. These were compared with the histological evaluation that determines the location of the lectin stained capillaries and the actin stained arteries. The processed images provided a 5 to 10-fold improvement in resolution when compared to conventional ultrasound. Entire arteries with diameters as small as 200μm were visualised with a less than 20% error in their measure diameter, compared to the spatial resolution of conventional ultrasound which is only 400μm in optimal conditions. In addition, small arterioles in the range of 40μm can also be visualised. Importantly, the super-resolution ultrasound ethod handled on average over 40,000 single scatter events per video loop. In individual image frames it was possible to identify up to 300 single microbubbles in the 1.5 mm x 1.5 mm region of interest of the CL. The new image analysis method enables super-resolution maps of the vascular bed using short duration video loop data captured by conventional 2D CEUS, confirming our original hypothesis. The robust detection and linking of microbubbles enables the automatic handling of large microbubblenumbers in each image, which in turn significantly reduces the required duration of the examination. This method is ready to be tested in patient data.

A semi-analytical model for the acoustic impedance of finite length circular holes with mean flow

The acoustic response of a circular hole with mean flow passing through it is highly relevant to Helmholtz resonators, fuel injectors, perforated plates, screens, liners and many other engineering applications. A widely used analytical model [M.S. Howe. “Onthe theory of unsteady high Reynolds number flow through a circular aperture”, Proc. of the Royal Soc. A. 366, 1725 (1979), 205‐223] which assumes an infinitesimally short hole was recently shown to be insufficient for predicting the impedance of holes with a finite length. In the present work, an analytical model based on Green׳s function method is developed to take the hole length into consideration for “short” holes. The importance of capturing the modified vortex noise accurately is shown. The vortices shed at the hole inlet edge are convected to the hole outlet and further downstream to form a vortex sheet. This couples with the acoustic waves and this coupling has the potential to generate as well as absorb acoustic energy in the low frequency region. The impedance predicted by this model shows the importance of capturing the path of the shed vortex. When the vortex path is captured accurately, the impedance predictions agree well with previous experimental and CFD results, for example predicting the potential for generation of acoustic energy at higher frequencies. For “long” holes, a simplified model which combines Howe׳s model with plane acoustic waves within the hole is developed. It is shown that the most important effect in this case is the acoustic non-compactness of the hole.

The Information Content of Systems in General Physical Theories

What kind of object is a quantum state? Is it an object that encodes an exponentially growing amount of information (in the size of the system) or more akin to a probability distribution? It turns out that these questions are sensitive to what we do with the information. For example, Holevo's bound tells us that n qubits only encode n bits of classical information but for certain communication complexity tasks there is an exponential separation between quantum and classical resources. Instead of just contrasting quantum and classical physics, we can place both within a broad landscape of physical theories and ask how non-quantum (and non-classical) theories are different from, or more powerful than quantum theory. For example, in communication complexity, certain (non-quantum) theories can trivialise all communication complexity tasks. In recent work [C. M. Lee and M. J. Hoban, Proc. Royal Soc. A 472 (2190), 2016], we showed that the immense power of the information content of states in general (non-quantum) physical theories is not limited to communication complexity. We showed that, in general physical theories, states can be taken as "advice" for computers in these theories and this advice allows the computers to easily solve any decision problem. Aaronson has highlighted the close connection between quantum communication complexity and quantum computations that take quantum advice, and our work gives further indications that this is a very general connection. In this work, we review the results in our previous work and discuss the intricate relationship between communication complexity and computers taking advice for general theories.

Systems biology of aging.

Human aging occurs at rates that vary widely between organisms and cell types. We hypothesize that in both cases, variation is due to differences in heat production, heat management and molecular susceptibility to heat-induced change. Metabolic rates have long been implored for their contributions to the aging process, with a negative correlation observed between basal metabolic rate and lifespan (Savage et al., Proc Natl Acad Sci U S A 104:4718–4723, 2007, Economos, Exp Gerontol 17:145–152, 1982, Keys et al., Metabolism 22:579–587, 1973, O’Connor et al., Comp Biochem Physiol Part A, Molr & Integr Physiol 133:835–842, 2002, Speakman, J Exp Biol 208:1717–1730, 2005, Poehlman, J Am Geriatrics Soc 41:552–559, 1993). Small amounts of heat are the well-known byproduct of metabolism and other biological processes, and despite their magnitude, are sufficient to elicit alterations in biomolecular characteristics (Somero, Ann Rev Physiol 57:43–68, 1995). Existing theories of aging suggest that damage occurs to the conformations or sequences of molecules, which only shifts focus onto the implied failure of repair mechanisms. Contrarily, heat-induced changes affect the behavioral characteristics of molecules and are thus able to persist “under the radar” of heat shock proteins and other canalizing mechanisms, which recognize only physical aberrancies (Rutherford and Lindquist, Nature 396:336–342, 1998, Siegal and Bergman, Proc Natl Acad Sci U S A 99:10528–10532, 2002, Waddington, Nature 150:563–565, 1942). According to our hypothesis, behavioral changes to the binding affinities, kinetics, motilities, and functionalities are dependent on minute energetic fields within and between molecules. Exposure to the thermal byproducts of metabolism cause heritable shifts in molecular interaction schemes and diminish the integrity of genetic and epigenetic networks. Restructured topologies alter the emergent properties of networks and are observed as the increased variation and decreased functionality associated with “aging” (Moorad and Promislow, Proc Royal Soc B Biol Sci 276:2271–2278, 2009, Soltow et al., Integr Comp Biol 50:844–854, 2010, Siegal et al.,Genetica 129:83–103, 2007, Promislow,Proc Biol sci/The Royal Soc 271:1225–1234, 2004, Southworth et al., PLoS Genet 5:e1000776, 2009, Rodwell et al.,PLoS Biol 2:e427, 2004). A major hurdle in the development of this hypothesis was overcome with the discovery of protein moonlighting: the phenomenon by which proteins assume drastically different functions independent of conformational change (Jeffery, Trends Biochem Sci 24:8–11, 1999). This molecular mechanism validates the hypothesis that network and behavioral changes can undergo somatic inheritance, and be accumulated by daughter cells over the course of a lifetime. Once a damage threshold has been surpassed, a system can no longer sustain life, and death results.

Catalysis of the Oxygen Reduction Reaction: Thin Layer Sonoelectrochemistry

The oxygen reduction reaction (ORR) is a multi-electron and -proton transfer mechanism. In acidic solution, the slow step is typically taken as the first electron transfer. O2 + e + H+ ⇌HO2 Even with platinum electrocatalysts, ORR kinetics impose parasitic losses of ~30 % in proton exchange membrane (PEM) H2|O2 fuel cells. Because of poor O2 reduction kinetics, H2is generated by steam reforming of natural gas rather than by water electrolysis.Typically, catalysis is achieved by chemical manipulation of the catalyst materials. Physical means, such as increased temperature and pressure, can also increase rates. One means to increase temperature and pressure is irradiation of a fluid with ultrasound so as to induce cavitation. Acoustic energy is carried by a wave that first compresses the fluid, then rarefies the fluid to form microscopic voids, and then compresses the fluid to collapse the voids. On collapse at the thin interface between the fluid and void, extreme temperature (T > 5000 K) and pressure (P > 103 atm) are generated.1 Ultrasound has been applied to electrochemical systems with the first studies undertaken by Coury, et. al.2 In these studies, cavitation was generated in a bulk electrolyte where electrodes were placed at a distance from a sonic horn or other ultrasound source. Large transport enhancements were observed, but effects on heterogeneous reactions were not observed. Bubbles introduced noise in the voltammetry and the distance between the ultrasound source and the electrodes allowed energy to dissipate. See Scheme 1.Here, the ORR is investigated by sonoelectrochemistry undertaken in a thin layer electrochemical cell,3,4where:Acoustic energy attenuates less in the thin layer and so impacts the electrode processes..Acoustic energy is reflected back into the condensed phases rather than pass into the less dense air phase.Frank cavitation is not observed and not necessary to the enhanced rate of the ORR. ORR rate is increased to the mass transport limit. As shown in Figure 1, on sonication in a thin layer, O2reduction proceeds at the mass transport limited rate. The experimental set up is shown in Figure 2.In general, sonication in a thin layer increases interfacial rates without significant impact on transport3,4 and provides a general, physical means to effect catalysis. References and Acknowledgments: Support of the National Science Foundation and the University of Iowa is gratefully acknowledged.[1] K.S. Suslick, Y. Didenko, M.M. Fang, T. Hyeon, K.J. Kolbeck, M.M. Mdleleni, and M. Wong, Acoustic Cavitation, Phil. Trans. Royal Soc. A 1999.[2] C.R.S Hagan R. S. and L.A. Coury Jr. Anal. Chem., 1994, 66(3), 399–405.[3] Chester G. Duda, Ph.D. dissertation, University of Iowa, 2012.[4] J. Leddy, C.G. Duda, and W.J. Leddy III, U.S. Patent application, 2013.

Thin Layer Sonoelectrochemistry

Ultrasound irradiation of electrodes in a thin electrolyte layer improves heterogeneous electron transfer kinetics.1,2 A bulk fluid irradiated with ultrasonic energy of sufficient intensity generates bubbles by compression and rarefaction. On bubble collapse, extremes of temperature (T ≳ 5000 K) and pressure (P ≳ 10³ atm) are generated at the narrow interface between the fluid and bubble void3. In bulk fluids, ultrasound enhances transport and impacts homogeneous reactions, but the energy attenuates. In prior sonoelectrochemical studies (first by Coury), bulk electrolyte was irradiated with sufficient ultrasonic intensity to generate cavitation. Cavitation increased homogeneous reaction rates, transport, and turbulence. No effects on heterogeneous electron transfer were found. In a thin layer sonoelectrochemical system (Figure 1), heterogeneous electron transfer rates increase. Thin layers have two advantages for harvesting sound energy2. Sound waves reflect back into the thin layer | air interface to retain energy. Losses from attenuation are less within thin layers. No frank cavitation is observed in thin layers.Electrolyte fills the well to form a meniscus. Cyclic voltammograms are recorded for each Ru(bpy)3 2+ and Fe3+ with and without sonication (Figure 2). Sonication intensity can be varied. Sonication has no impact on the voltammetry for Ru(bpy)3 2+ for which electron transfer rates are rapid compared to the scan rate. Sonication does not impact transport. Rates of Fe3+ reduction increases with sonication intensity, as shown by the more rapid rise in current on sonication. Peak potentials shift because the reference is shifting. Where rates are slow, sonication increases heterogeneous electron transfer rates without significantly impact on diffusional transport1. References and Acknowledgments: Support of the National Science Foundation and the University of Iowa is gratefully acknowledged. With thanks to Andrej Wieckowski for his explorations and contributions to understanding electrocatalysis. [1] Chester G. Duda, Ph.D. dissertation, University of Iowa, 2012.[2] J. Leddy, C.G. Duda, and W.J. Leddy III, Provisional U.S. Patent application, 2013.[3] K.S. Suslick, Y. Didenko, M.M. Fang, T. Hyeon, K.J. Kolbeck, M.M. Mdleleni, and M. Wong, Acoustic Cavitation, Phil. Trans. Royal Soc. A 1999.

Further study of rubber-like elasticity: elastic potentials matching biaxial data

By virtue of the rational interpolation procedure and logarithmic strain, a direct approach is proposed to obtain elastic potentials that exactly match uniaxial data and shear data for elastomers. This approach reduces the determination of multiaxial elastic potentials to that of two one-dimensional potentials, thus bypassing usual cumbersome procedures of identifying a number of unknown parameters. Predictions of the suggested potential are derived for a general biaxial stretch test and compared with the classical data given by Rivlin and Saunders (Rivlin, R. S. and Saunders, D. W. Large elastic deformation of isotropic materials. VII: experiments on the deformation of rubber. Phill. Trans. Royal Soc. London A, 243, 251–288 (1951)). Good agreement is achieved with these extensive data.

Singular Limiting Induced from Continuum Solutions and the Problem of Dynamic Cavitation

In the works of Pericak-Spector and Spector (Arch Rational Mech Anal. 101:293–317, 1988, Proc. Royal Soc. Edinburgh Sect A 127:837–857, 1997) a class of self-similar solutions are constructed for the equations of radial isotropic elastodynamics that describe cavitating solutions. Cavitating solutions decrease the total mechanical energy and provide a striking example of non-uniqueness of entropy weak solutions (for polyconvex energies) due to point-singularities at the cavity. To resolve this paradox, we introduce the concept of singular limiting induced from continuum solution (or slic-solution), according to which a discontinuous motion is a slic-solution if its averages form a family of smooth approximate solutions to the problem. It turns out that there is an energetic cost for creating the cavity, which is captured by the notion of slic-solution but neglected by the usual entropic weak solutions. Once this cost is accounted for, the total mechanical energy of the cavitating solution is in fact larger than that of the homogeneously deformed state. We also apply the notion of slic-solutions to a one-dimensional example describing the onset of fracture, and to gas dynamics in Langrangean coordinates with Riemann data inducing vacuum in the wave fan.

Difference analogues of the second main theorem for meromorphic functions in several complex variables

In this paper, we obtain difference analogues of the second main theorem for meromorphic functions in several complex variables from which difference analogues of Picard‐type theorems are also obtained. Our results are improvements or extensions of some recent results of papers [Proc. Royal Soc. Edinburgh Section A Math. 137, 457–474 (2007); Comput. Meth. Funct. Theor. 12, No. 1, 343–361 (2012)]. The method we used is very different from theirs.

Fatigue from defect under multiaxial loading: Defect Stress Gradient (DSG) approach using ellipsoidal Equivalent Inclusion Method

The fatigue design of metallic parts depends on the casting process. It requires a compromise between the fatigue resistance of the component and the allowable defect size due to the process. The research team has proposed, in previous work [Leopold G, Nadot Y. J ASTM Int 7:2010], to represent the effect of a defect in the fatigue criterion by means of a stress gradient term. This general methodology called Defect Stress Gradient (DSG) can consider explicitly the type, the morphology and the size of the defect due to the fact that a Finite Element (FE) submodel describes directly the defect at the mesoscopic scale. The DSG approach gives correct results for the defects range from 100 to 1000μm but it is limited for application to full scale components by the use of FE submodel. The aim of this paper is to present an upgraded version of the DSG approach using the Equivalent Inclusion Method (EIM) due to Eshelby [Eshelby JD. Proc Royal Soc Lond Ser A. Math Phys Sci 241:1957; 376–96], [Eshelby JD. Elastic inclusions and inhomogeneities. In: Sneddon IN, Hill R (Eds.), Progress in solid mechanics 2. Amsterdam: North-Holland Publishing Company; 1961. p. 89–140] to compute stresses around the defect. Using this analytical approach, it is possible to compute the stresses around an ellipsoidal defect without FE simulations. Furthermore, the EIM for an ellipsoidal defect is efficient to address the question of the defect size related to loading direction in the case of a non-spherical defect. Although the framework of the original EIM is for internal defect, this paper shows that its application for a surface defect gives fair results in the context of the DSG approach. The new DSG proposal is evaluated on a low carbon steel, containing ellipsoidal defects with different orientations, under tension and torsion fatigue loadings.