bluuebunny/crossref_metadata_2025 huggingface dataset:
Chevalier Jackson: pioneer and protector of children
Authors: Giddings C E B , Rimmer J , Weir N
Published: May 2013

Chevalier Jackson was one of the greatest pioneers of otolaryngology. He was a pioneer of oesophagoscopy, bronchoscopy and the removal of foreign bodies. He changed the mortality rate for an airway foreign body from 98 per cent to a survival rate of 98 per cent. He became distressed by the number of preventable injuries in children from the ingestion of caustic substances, most commonly household lye. His experiences of children with oesophageal stricturing secondary to caustic ingestion moved him to start a campaign to force manufacturers to label all poisonous substances as such. This took him from the American Senate to the House of Representatives and back again; the Federal Caustic Poisons Act (1927) is still enforced today. In a career with over 400 publications, written during exacerbations of his pulmonary tuberculosis, his life story is a remarkable one, only part of which is widely known.
Dietary management of the metabolic syndrome – one size fits all?
Authors: Champagne Catherine M. , Bray George A.
Published: May 2013

Diagnosis of metabolic syndrome includes a set of laboratory and physical findings, including central adiposity, elevated TAG, reduced HDL-cholesterol, hypertension and elevated fasting glucose or insulin resistance. While definitions have varied slightly, from a practical point of view, identifying dietary and lifestyle factors, including low levels of physical activity, are important in designing a diet and exercise programme that can help individuals with the metabolic syndrome to reduce the associated detrimental health consequences. Specific features of the metabolic syndrome require intervention, whether dietary or otherwise, to move towards normal ranges. It is important to remember that no one size or treatment fits all. While central obesity is perceived as the hallmark of the metabolic syndrome, other features need to be treated independently if they do not respond to lifestyle change. The future may hold treatments for the metabolic syndrome that involve modulation of inflammation.
Understanding – and Misunderstanding – Social Mobility in Britain: The Entry of the Economists, the Confusion of Politicians and the Limits of Educational Policy
Authors: GOLDTHORPE JOHN H.
Published: May 2013

A consensus has developed in political and also media circles that in Britain over recent decades social mobility has been in decline. According to the consensus view, as construed in political circles, educational policy is seen as the crucial instrument for increasing mobility. This article shows how the consensus emerged from the research of a group of economists into intergenerational income mobility. It is argued that, primarily on account of various limitations of the available data, the economists’ finding of declining mobility is open to question; and, further, that, because no explicit distinction is made in their work between absolute and relative rates of mobility, its reception, among politicians especially, has been attended by considerable confusion. An alternative to the consensus view is put forward, based on extensive research by sociologists into social class mobility, which is seen as better capturing the intergenerational transmission of economic advantage and disadvantage. This research indicates that the only recent change of note is that the rising rates of upward, absolute mobility of the middle decades of the last century have levelled out. Relative rates have remained more or less constant back to the inter-war years. According to this alternative view, what can be achieved through education, whether in regard to absolute or relative mobility, appears limited.
Regularity of source-type solutions to the thin-film equation with zero contact angle and mobility exponent between 3/2 and 3
Authors: GIACOMELLI LORENZO , GNANN MANUEL V. , OTTO FELIX
Published: May 2013

In one space dimension, we consider source-type (self-similar) solutions to the thin-film equation with vanishing slope at the edge of their support (zero contact-angle condition) in the range of mobility exponents $n\in\left(\frac 3 2,3\right)$. This range contains the physically relevant case n=2 (Navier slip). The existence and (up to a spatial scaling) uniqueness of these solutions has been established in [3] (Bernis, F., Peletier, L. A. & Williams, S. M. (1992) Source type solutions of a fourth-order nonlinear degenerate parabolic equation. Nonlinear Anal. 18, 217–234). It is also shown there that the leading-order expansion near the edge of the support coincides with that of a travelling-wave solution. In this paper we substantially sharpen this result, proving that the higher order correction is analytic with respect to two variables: the first one is just the spatial variable whereas the second one is a (generically irrational, in particular for n=2) power of it, which naturally emerges from a linearisation of the operator around the travelling-wave solution. This result shows that – as opposed to the case of n=1 (Darcy) or to the case of the porous medium equation (the second-order analogue of the thin-film equation) – in this range of mobility exponents, source-type solutions are not smooth at the edge of their support even when the behaviour of the travelling wave is factored off. We expect the same singular behaviour for a generic solution to the thin-film equation near its moving contact line. As a consequence, we expect a (short-time or small-data) well-posedness theory – of which this paper is a natural prerequisite – to be more involved than in the case n=1.
Finite volume and pseudo-spectral schemes for the fully nonlinear 1D Serre equations
Authors: DUTYKH DENYS , CLAMOND DIDIER , MILEWSKI PAUL , MITSOTAKIS DIMITRIOS
Published: May 2013

After we derive the Serre system of equations of water wave theory from a generalized variational principle, we present some of its structural properties. We also propose a robust and accurate finite volume scheme to solve these equations in one horizontal dimension. The numerical discretization is validated by comparisons with analytical and experimental data or other numerical solutions obtained by a highly accurate pseudo-spectral method.
Frontal Defects Contribute to the Genesis of Closing-in in Alzheimer's Disease Patients
Authors: De Lucia Natascia , Grossi Dario , Maria Fasanaro Angiola , Carpi Sabrina , Trojano Luigi
Published: May 2013

Closing-in (CI) refers to copying drawings near to or superimposed on the original model, and is often observed in Alzheimer's disease (AD) patients. Contrasting hypotheses have been suggested to explain CI, but no prospective study has directly verified these interpretations. We evaluated the role of frontal/executiveversusvisuo-spatial impairments in a prospective sample of AD patients, and also explored whether different types of CI are related to specific neuropsychological tasks. We enrolled 64 AD patients who underwent copying tasks and an extensive neuropsychological assessment of visuo-spatial and visuo-constructional skills, frontal/executive abilities and anterograde memory. AD patients with CI showed more severe impairment on frontal/executive functions than AD patients without CI. Moreover, the tendency to produce copies superimposed on the model was selectively associated with poor inhibitory control for irrelevant responses. On this basis, we suggest that different CI phenomena could be ascribed to distinctive frontal/executive defects. (JINS, 2013,19, 1–7)
Adherence to a snacking dietary pattern and soda intake are related to the development of adiposity: a prospective study in school-age children
Authors: Shroff Monal R , Perng Wei , Baylin Ana , Mora-Plazas Mercedes , Marin Constanza , Villamor Eduardo
Published: May 2013

Objective

Snacking has been related to increased prevalence of overweight among school-age children in cross-sectional studies. It is uncertain, however, whether snacking influences the development of adiposity over time.

Design

We examined whether adherence to a snacking dietary pattern was associated with greater increases in children's BMI, subscapular:triceps skinfold thickness ratio and waist circumference over a median 2·5-year follow-up. Dietary patterns were identified through principal component analysis of an FFQ administered at recruitment in 2006. Anthropometric follow-up was conducted annually. Linear mixed-effects models were used to estimate rates of change in each indicator according to quartiles of adherence to the snacking pattern. We also examined change in BMI, subscapular:triceps skinfold thickness ratio and waist circumference in relation to intake of the food items in the snacking pattern.

Subjects

Children (n 961) 5–12 years of age.

Setting

Public schools in Bogotá, Colombia.

Results

After adjustment for age, sex, total energy intake and socio-economic status, children in the highest quartile of adherence to the snacking pattern had a 0·09 kg/m2 per year higher BMI gain than children in the lowest quartile (P trend = 0·05). A similar association was observed for mean change in subscapular:triceps skinfold thickness ratio (highest v. lowest quartile difference = 0·012/year; P = 0·03). Of the food items in the snacking pattern, soda intake was positively and significantly associated with change in BMI (P trend = 0·01) and waist circumference (P trend = 0·04) in multivariable analysis.

Conclusions

Our results indicate that snacking and soda intake are associated with development of adiposity in school-age children.
Quantification and Morphology Studies of Nanoporous Alumina Membranes: A New Algorithm for Digital Image Processing
Authors: Choudhari Khoobaram S. , Jidesh Pacheeripadikkal , Sudheendra Parampalli , Kulkarni Suresh D.
Published: May 2013

A new mathematical algorithm is reported for the accurate and efficient analysis of pore properties of nanoporous anodic alumina (NAA) membranes using scanning electron microscope (SEM) images. NAA membranes of the desired pore size were fabricated using a two-step anodic oxidation process. Surface morphology of the NAA membranes with different pore properties was studied using SEM images along with computerized image processing and analysis. The main objective was to analyze the SEM images of NAA membranes quantitatively, systematically, and quickly. The method uses a regularized shock filter for contrast enhancement, mathematical morphological operators, and a segmentation process for efficient determination of pore properties. The algorithm is executed using MATLAB, which generates a statistical report on the morphology of NAA membrane surfaces and performs accurate quantification of the parameters such as average pore-size distribution, porous area fraction, and average interpore distances. A good comparison between the pore property measurements was obtained using our algorithm and ImageJ software. This algorithm, with little manual intervention, is useful for optimizing the experimental process parameters during the fabrication of such nanostructures. Further, the algorithm is capable of analyzing SEM images of similar or asymmetrically porous nanostructures where sample and background have distinguishable contrast.
Wh-Optatives in Danish: Compositional and Noncompositional Aspects
Authors: Ørsnes Bjarne
Published: May 2013

Danish has an optative taking the form of awh-clause with embedded word order:Hvem der var rig!lit. ‘Who there were rich!’ with the intended meaningWish I were rich!Suchwh-clauses cannot be used as optatives in German or English (or only marginally so). On the basis of a detailed analysis of the syntax, semantics, and pragmatics of this little-studied phenomenon, this article seeks to explain why awh-clause with “embedded” word order can be used as an optative. I argue thatwh-optatives are compositional in many but not all respects. It is a special construction whose interpretation is determined to a large extent by its grammatical properties but which also has completely idiosyncratic properties. In German and English, suchwh-clauses are only potential optatives: They are not used as optatives, but nothing would preclude it.*
W-band active loads and switching front-end MMICs for radiometer calibration
Authors: Weissbrodt Ernst , Schlechtweg Michael , Ambacher Oliver , Kallfass Ingmar
Published: May 2013

A millimeter-wave monolithic integrated circuit consisting of a W-band (75–100 GHz) single-pole-five-throw (SP5T) switch and multiple internal active and passive loads for radiometer calibration was designed and manufactured in a low noise 50 nm GaAs metamorphic high electron mobility transistor technology. This highly compact and integrated front-end device for radiometer systems is capable of ultra fast switching between two identical input ports (e.g. for polarimetric applications) and three internal calibration references. It allows an accurate multi-load calibration with noise temperatures between 220 and 1750 K at the output of the device. Compared to conventional calibration methods this marks a substantial advantage in terms of size, mass, power consumption, complexity, and repetition rate.
NLRP3 activation induces ASC-dependent programmed necrotic cell death, which leads to neutrophilic inflammation
Authors: Satoh T , Kambe N , Matsue H
Published: May 2013

NLR family pyrin domain containing 3 (NLRP3) is a cytoplasmic pattern recognition receptor that regulates innate immune responses by forming a protein complex, the inflammasome. It leads to production of proinflammatory cytokine productions such as interleukin 1β (IL-1β). We and others demonstrated that an induction of activated NLRP3 also induced cell death. However, little is known about the characteristics and mechanisms of the cell death and its involvement in the pathogenesis of inflammatory conditions. In this study, we established cell lines in which NLRP3 was induced by doxycycline using a tetracycline-inducible expression (Tet-on) system. Using this system, the expression of NLRP3 mutants in cryopyrin-associated periodic syndrome (CAPS) patients was sufficient for the induction of necrotic cell death without lipopolysaccharide stimulation or generation of mature IL-1β. We also found that CA074-Me, a cathepsin B inhibitor, blocked cell death before oligomerization of apoptosis-associated speck-like protein containing a CARD (ASC), whereas Z-VAD-fmk, a pan-caspase inhibitor, blocked the cell death after the oligomerization. Silencing of the ASC gene (Pycard) by small hairpin RNA treatment inhibited the NLRP3 mutant-induced cell death, but silencing of the caspase-1 gene (Casp1) did not. Taken together, these results indicated that ASC was indispensable for NLRP3-mediated programmed necrotic cell death, and that this type of cell death was distinct from ‘pyroptosis’, which requires caspase-1. Finally, we demonstrated in an in vivo model that the programmed necrotic cell death induced by activated NLRP3 could cause neutrophil infiltration, indicating a possible role of cell death in neutrophil infiltration of skin lesions in CAPS patients.
Functional Polymers for Nanomedicine
Authors:   Royal Society of Chemistry,   Royal Society of Chemistry
Published: May 2013

Interest in the application of nanotechnology to medicine has surged in recent years and could transform the way we diagnose, treat and prevent diseases such as cancer. However, the clinical success of nanomedicine is limited because of problems with toxicity and therapeutic efficacy. To overcome this it is essential to produce new nanosystems with specific functions, which can be achieved by designing new polymers with particular properties that can be used for nanomedicine. Functional Polymers for Nanomedicine provides a complete overview of the different strategies for designing polymers for nanomedicine applications. The first part of the book looks at the current problems and direction in nanomedicine including a review of current design and targeting of nanocarriers. The second part explores the design of polymers with different functions including hyperbranched polymers, polymersomes, polysaccharides, polymeric micelles and zwitterionic polymers and their applications in gene therapy and drug delivery. This timely book is edited by a leading scientist in nanomedicine and provides a suitable introduction and reference source for advanced undergraduates, postgraduates and academic and industrial researchers in polymer science, nanotechnology and pharmacy interested in materials for medical applications.
Kinetics and Thermodynamics of Radical Polymerization
Authors: Ehlers F. , Barth J. , Vana P.
Published: May 2013

The intention of the following chapter is to give a general overview of our knowledge about the kinetics of conventional radical polymerization and its implications for the process and the formed product. This basic knowledge is also essential for the understanding and optimization of controlled polymerization processes.
Controlled/Living Radical Polymerization in the Presence of Iniferters
Authors: Atilla Tasdelen Mehmet , Yagci Yusuf
Published: May 2013

Conventional free radical polymerization is limited in its inability to control polymer properties such as average molecular weight, molecular weight distribution and end-group functionality. New processes are being developed, in which the free radical propagating chain is reversibly terminated, allowing the free radical polymerization to behave in a controlled fashion. The first step in the development of controlled/living radical polymerization (C/LRP) dates back to the early 1980s when it was found that the use of iniferter (namely, agents that initiate, transfer, and terminate) systems exhibited a degree of livingness. Iniferter methodology can be used to polymerize most vinyl monomers under mild reaction conditions via thermal, redox and photochemical activations. The present chapter reviews recent advances in the use of iniferters in the C/LRP, their benefits, and current limitations. Applications of iniferters for the synthesis of telechelic polymers, complex macromolecular architectures and modification of surfaces are also discussed.
Controlled/Living Radical Polymerization Mediated by Stable Organic Radicals
Authors: Nesvadba Peter
Published: May 2013

The development of stable-radical mediated polymerization (SRMP) from its origins with focus on nitroxide-mediated radical polymerization (NMP) is reviewed. The underlying persistent radical effect, mechanistic steps, fundamental kinetic equations and side reactions of NMP are discussed. The most important nitroxides and alkoxyamine initiators for NMP are presented, along with the parameters influencing the rate constants of cleavage and reformation of alkoxyamines. Applications of NMP for synthesis of complex polymeric structures and in industry are shown, and advances in nitroxide-mediated photopolymerization (NMPP) are discussed. SRMP with the most important non-nitroxide stable organic radicals as well as the organometallic-mediated radical polymerization (OMRP) are briefly mentioned.
Mechanistic Aspects of Living Radical Polymerization Mediated by Organometallic Complexes
Authors: Ye Zichuan , Wayland Bradford B.
Published: May 2013

The capabilities, limitations and future expectations for organometallic complexes in the mediation of living radical polymerizations (LRP) are briefly reviewed. Emphasis is placed on the illustrating the electronic, structural, kinetic and thermodynamic factors that contribute to obtaining LRP by reversible termination (RT) and degenerative transfer pathways using organometallic metallic living radical polymerization (OMRP). Mechanistic features of OMRP are primarily illustrated by using cobalt (IIII) porphyrin and organo-cobalt porphyrin complexes that played a central role in establishing guidelines for structural, thermodynamic and kinetic criteria to obtain OMRP by reversible termination and degenerative transfer pathways. The capability of cobalt acetylacetonate (Co(acac)2 ) to mediate the precise LRP of vinyl acetate (VA) illustrate how this exceptional property arises from the highly unusual set of structural, electronic and thermodynamic properties. Applications in polymeric materials synthesis where OMRP is the preferred or exclusive method are summarized.
Fundamentals of RAFT Polymerization
Authors: Moad Graeme , Rizzardo Ezio , Thang San H.
Published: May 2013

This chapter sets out to describe the fundamental aspects of radical polymerization with reversible addition-fragmentation chain transfer (RAFT polymerization). Following a description of the mechanism we describe aspects of the kinetics of RAFT polymerization, how to select a RAFT agent to achieve optimal control over polymer molecular weight, composition and architecture, and how to avoid side reactions which might lead to retardation or inhibition.
Phosphines and related P–C‐bonded compounds
Authors: Allen D. W.
Published: May 2013

This chapter reviews the literature published during 2011 relating to the above area, apart from a few papers from 2010 in less accessible journals which came to light in Chemical Abstracts in 2011. Synthetic routes to phosphines are reported, together with studies of their reactivity towards various atomic and molecular electrophilic sites involving carbon, halogen, boron, nitrogen and other acceptors. Also reported are studies of developments in the chemistry of low coordination number pπ-bonded phosphorus compounds and related potentially aromatic heterocyclic phosphorus systems.
Phosphine chalcogenides
Authors: Keglevich G.
Published: May 2013

Phosphine chalcogenides, such as oxides, sulfides and selenides form a representative group of organophosphorus compounds. This chapter discusses the new synthetic methods for phosphine chalcogenides. These include synthesis from elemental phosphorus, from P(III)‐ and P(IV)‐chlorides, >P(O)H species and the modification of other organophosphorus compounds. The families of compounds synthesized include alicyclic and aromatic derivatives, P‐heterocycles, as well as N‐ and O‐heterocyclic derivatives, macrocycles and macromolecules. Properties and reactions of phosphine chalcogenides are also discussed. The reactions include modifications, deoxygenations and complexations
Quinquevalent phosphorus acids
Authors: Bałczewski Piotr , Skalik Joanna
Published: May 2013

This chapter shows the most important achievements in the area compounds containing three P–O bonds (phosphates), two P–O and one P–C bonds (phosphonates) as well as one P–O and two P–C bonds (phosphinates) in addition to the phosphoryl group P=O. Each of the main sections has been divided in the same way, covering synthesis, reactions and biological aspects. In all three sections, there has been good coverage of the traditional subjects like new reagents, new methods of synthesis, total syntheses, stereocontrolled syntheses proceeding with good diastereoselectivities and enantioselectivities. Practical aspects of phosphorus chemistry has been realized by analysis of biological and medicinal applications of active compounds.

In this year, a subsection concerning use of chiral phosphoric acids as catalysts in various chemical reactions, introduced in 2009 for the first time, has been maintained and expanded with new categories due to further, rapid progress in this area. In the subsection: reactions of phosphoric acids and their derivatives, total syntheses of valuable, biologically active compounds have been presented in the literature of the review period too.
Pentacoordinated and hexacoordinated compounds
Authors: Pajkert Romana , Röschenthaler Gerd‐Volker
Published: May 2013

This chapter provides an update on the chemistry of hypervalent phosphorus compounds, bringing in concise form advances in their preparation, application and structural properties, which have been published in 2011. A major portion of this research has been devoted to pentacoordinated compounds whereas relatively little has appeared on hexacoordinate chemistry.
Phosphazenes
Authors: Stewart Frederick F.
Published: May 2013

Phosphazenes remain an intriguing chemical system due to the unique incorporation of phosphorus and nitrogen into other organic and inorganic molecules. Typically, phosphazenes serve as scaffolds to which a variety of other molecular structures can be appended. Since phosphorus is pentavalent in phosphazene structures, two attachment points exist through which other molecules can be attached. It should be noted that this diverse chemistry is not limited to simple appendages, but the phosphorus and nitrogen structure itself can be manipulated into a range of molecules spanning from small molecule forms to macromolecular polymers. Furthermore, the incorporation of phosphazenes into organic systems provides much in the way of property enhancement. In this article, both continuing research into the application of specific phosphazenes and the formation of novel structures are reviewed. Applications, in many cases, appear to be the driving force behind much of the new research. Themes presented in this article include advances in phosphazene materials for energy storage, optical applications, biomedical tissue replacement, and immunoadjuvants; however the goal is to present these applications in terms of new chemical understanding of structure and function.
Physical methods
Authors: Slinn Robert N.
Published: May 2013

This chapter highlights the major physical methods, analytical techniques, theoretical and computational methods reported in organophosphorus chemistry research publications during 2012. As in previous years, it has been divided appropriately into eleven main sections and relevant subsections. These are:‐ Theoretical and Computational Chemistry methods, NMR spectroscopy, EPR spectroscopy, Vibrational (IR and Raman) spectroscopy, Electronic (UV‐Visible, Fluorescence, and Luminescence) spectroscopy, X‐ray (XRD) structural studies, Electrochemical (Voltammetry, Sensors and Biosensors) methods, Thermodynamics and Thermochemistry and Thermal methods, Mass spectrometry, Chromatography and related separation techniques (including GC‐MS and LC‐MS), and finally a short section on Kinetics.
Nucleotides and polynucleotides: mononucleotides
Authors: Loakes David
Published: May 2013

This chapter covers the publications regarding nucleotides for the year 2011. The major areas of interest have been in the use of nucleotides as building blocks in oligonucleotide synthesis (phosphoramidites and in particular triphosphates), but especially the use of nucleotides as potential therapeutic agents. Amongst the therapeutic analogues two main areas continue to be of interest, namely the design of pro‐nucleotides, analogues designed to bypass the first phosphorylation step towards triphosphate synthesis in vivo, and secondly nucleoside phosphonates. In addition to pro‐nucleotides there are reports of masked phosphates aimed at aiding cell penetration. As in previous years there are also many reports of chemical modifications of pyro‐ and poly‐phosphate derivatives. Each section also has an update on synthesis and synthetic methods.
Revisiting the hot matter in the center of gamma-ray bursts and
supernovae
Authors: Li Ang , Liu Tong
Published: May 2013

Aims. Hot matter with nucleons can be produced in the inner region of
the neutrino-dominated accretion flow in gamma-ray bursts or during the proto-neutron star
birth in successful supernovae. The composition and equation of state of the matter depend
on the dynamic β equilibrium under various neutrino opacities. The strong
interaction between nucleons may also play an important role. We plan to extend the
previous studies by incorporating these two aspects in our model.

Methods. The modification of the β-equilibrium
condition from neutrino optically thin to thick was modeled by an equilibrium factor
χ ranging between the neutrino-freely-escaping case and the
neutrino-trapped case. We employed the microscopic Brueckner-Hartree-Fock approach
extended to the finite temperature regime to study the interacting nucleons.

Results. We show the composition and chemical potentials of the hot
nuclear matter for different densities and temperatures at each stage of
β equilibrium. We also compare our realistic equation of states with
those of the free-gas model. We find that it is important to properly describe the
neutrino opacity and the strong interaction between nucleons, and they should be taken
into account in model calculations.
Symplectic quantum mechanics and Chern-Simons gauge theory. I
Authors: Jeffrey Lisa C.
Published: May 2013

In this article we describe the relation between the Chern-Simons gauge theory partition function and the partition function defined using the symplectic action functional as the Lagrangian. We show that the partition functions obtained using these two Lagrangians agree, and we identify the semiclassical formula for the partition function defined using the symplectic action functional.
A platform for retaining native morphology at sub-second time scales in cryogenic transmission electron microscopy
Authors: Croote Derek , Godfrin Michael P. , Bose Arijit , Tripathi Anubhav , Lee Jinkee
Published: May 2013

The advantage of cryogenic transmission electron microscopy for morphological analysis of complex fluids is the ability to capture native specimen morphology in solution. This is often limited by available sample preparation devices and procedures, which expose the sample to high shear rates leading to non-native artifacts, are unable to capture evolving samples at a time resolution shorter than a few seconds, and often non-specifically adsorb sample species from suspension resulting in a non-native sample concentration on the grid. In this paper we report the development of a new sample preparation device based on capillary action that overcomes all of these limitations. The use of a removal capillary placed parallel to the grid results in reduced shear and lower absorption of particulate material from the sample. A deposition capillary placed perpendicular to the grid allows for precise and sub-second resolution for time resolved studies. We demonstrate each of the features of this platform using model samples, and where appropriate, compare our results to those prepared using current vitrification platforms. Our results confirm that this new sample vitrification device opens up previously unattainable regimes for sample preparation and imaging and is a powerful new tool for cryogenic transmission electron microscopy.
Weakly nonlinear electrophoresis of a highly charged colloidal particle
Authors: Schnitzer Ory , Zeyde Roman , Yavneh Irad , Yariv Ehud
Published: May 2013

At large zeta potentials, surface conduction becomes appreciable in thin-double-layer electrokinetic transport. In the linear weak-field regime, where this effect is quantified by the Dukhin number, it is manifested in non-Smoluchowski electrophoretic mobilities. In this paper we go beyond linear response, employing the recently derived macroscale model of Schnitzer and Yariv [“Macroscale description of electrokinetic flows at large zeta potentials: Nonlinear surface conduction,” Phys. Rev. E 86, 021503 (2012)10.1103/PhysRevE.86.021503] as the infrastructure for a weakly nonlinear analysis of spherical-particle electrophoresis. A straightforward perturbation in the field strength is frustrated by the failure to satisfy the far-field conditions, representing a non-uniformity of the weak-field approximation at large distances away from the particle, where salt advection becomes comparable to diffusion. This is remedied using inner-outer asymptotic expansions in the spirit of Acrivos and Taylor [“Heat and mass transfer from single spheres in Stokes flow,” Phys. Fluids 5, 387 (1962)10.1063/1.1706630], with the inner region representing the particle neighborhood and the outer region corresponding to distances scaling inversely with the field magnitude. This singular scheme furnishes an asymptotic correction to the electrophoretic velocity, proportional to the applied field cubed, which embodies a host of nonlinear mechanisms unfamiliar from linear electrokinetic theories. These include the effect of induced zeta-potential inhomogeneity, animated by concentration polarization, on electro-osmosis and diffuso-osmosis; bulk advection of salt; nonuniform bulk conductivity; Coulomb body forces acting on bulk volumetric charge; and the nonzero electrostatic force exerted upon the otherwise screened particle-layer system. A numerical solution of the macroscale model validates our weakly nonlinear analysis.
Analogue of the mass conservation law for third approximation of one-dimensional nonlinear Boltzmann's moment system equations
Authors: Sakabekov A. , Auzhani E.
Published: May 2013

In this article, we prove the analogue of the mass conservation law for one-dimensional nonlinear Boltzmann's moment system equations in third approximation and some effect of the mass conservation law.
Influence of the geometry on the two- and three-dimensional dynamics of the flow in a 180° sharp bend
Authors: Zhang Lintao , Pothérat Alban
Published: May 2013

An analysis of the successive regimes of the two-dimensional (2D) flow through a sharp 180° bend is performed by means of parametric numerical simulations where the Reynolds number Re and the opening ratio β (defined as the ratio of bend opening to the inlet width) vary in the respective ranges [0–2500] and [0.1–10]. In the outlet, the sequence of flow regimes is found to bear similarities with the flow behind a two-dimensional cylinder, despite being asymmetric by nature: when Re was increased, we found a laminar flow, then a flow with a first recirculation attached to the inside boundary, then one with a second recirculation attached to the top boundary. The onset of unsteadiness occurs through instability of the main stream and vortex shedding from the inside boundary. For β ⩽ 0.2, the flow is characterised by the dynamics of the jet generated at the very small turning part whereas for β ⩾ 0.3, it behaves rather like the flow behind an obstacle placed in a channel. This difference is most noticeable in the unsteady regimes where the vortex shedding mechanisms differ. While the former generates a more turbulent flow rich in small scale turbulence, the latter produces large structures of the size of the channel. In the turning part, further series of recirculation develop in each corner, akin to those identified by Moffatt [“Viscous and resistive eddies near a sharp corner,” J. Fluid Mech. 18, 1 (1964)10.1017/S0022112064000015]. For β > 1 corresponding eddies merge to form a series of alternately rotating recirculating cells, which occupy the whole width of the turning part. We find that for β > 1, the effective opening ratio β*, which correspond to the area occupied by the mainstream while passing from the inlet to the outlet, tends towards a value of ≃0.7. The combination of regimes in the outlet and the turning part yields a wealth of flow regimes, which open interesting possibilities to tailor the design of 180° bends to suit particular applications involving mixing, heat, and mass transfer. Selected 3D simulations show that with a few noticeable exceptions, 2D dynamics determine the main features of the flow (drag and recirculation length), even in a wide bend, while 3D structure tends to slow down the shedding mechanism. 2D simulations are thus not only relevant to configurations where the flow is expected to be 2D (thin bend, MHD flows), but also to 3D flows where they can predict some of the global flow features at a low computational cost.
High temperature and pressure electrochemical test station
Authors: Chatzichristodoulou C. , Allebrod F. , Mogensen M.
Published: May 2013

An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 °C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive media, as well as localized sampling of gas evolved at the electrodes for gas analysis. A number of safety and engineering design challenges have been addressed. Furthermore, we present a series of electrochemical cell holders that have been constructed in order to accommodate different types of cells and facilitate different types of electrochemical measurements. Selected examples of materials and electrochemical cells examined in the test station are provided, ranging from the evaluation of the ionic conductivity of liquid electrolytic solutions immobilized in mesoporous ceramic structures, to the electrochemical characterization of high temperature and pressure alkaline electrolysis cells and the use of pseudo-reference electrodes for the separation of each electrode contribution. A future perspective of various electrochemical processes and devices that can be developed with the use of the established test station is provided.
Entropy and complexity analysis of hydrogenic Rydberg atoms
Authors: López-Rosa S. , Toranzo I. V. , Sánchez-Moreno P. , Dehesa J. S.
Published: May 2013

The internal disorder of hydrogenic Rydberg atoms as contained in their position and momentum probability densities is examined by means of the following information-theoretic spreading quantities: the radial and logarithmic expectation values, the Shannon entropy, and the Fisher information. As well, the complexity measures of Crámer-Rao, Fisher-Shannon, and López Ruiz-Mancini-Calvet types are investigated in both reciprocal spaces. The leading term of these quantities is rigorously calculated by use of the asymptotic properties of the concomitant entropic functionals of the Laguerre and Gegenbauer orthogonal polynomials which control the wavefunctions of the Rydberg states in both position and momentum spaces. The associated generalized Heisenberg-like, logarithmic and entropic uncertainty relations are also given. Finally, application to linear (l = 0), circular (l = n − 1), and quasicircular (l = n − 2) states is explicitly done.
Rim instability of bursting thin smectic films
Authors: Trittel Torsten , John Thomas , Tsuji Kinko , Stannarius Ralf
Published: May 2013

The rupture of thin smectic bubbles is studied by means of high speed video imaging. Bubbles of centimeter diameter and film thicknesses in the nanometer range are pierced, and the instabilities of the moving rim around the opening hole are described. Scaling laws describe the relation between film thickness and features of the filamentation process of the rim. A flapping motion of the retracting smectic film is assumed as the origin of the observed filamentation instability. A comparison with similar phenomena in soap bubbles is made. The present experiments extend studies on soap films [H. Lhuissier and E. Villermaux, Phys. Rev. Lett. 103, 054501 (2009)10.1103/PhysRevLett.103.054501] to much thinner, uniform films of thermotropic liquid crystals.
Amplified quenching of conjugated polymer nanoparticle photoluminescence for robust measurement of exciton diffusion length
Authors: Bjorgaard Josiah A. , Köse Muhammet E.
Published: May 2013

A new method for measuring exciton diffusion length in nanoparticles (NPs) of conjugated materials is presented. Cationic acceptor dyes are used to quench the photoluminescence in NPs of the prototypical conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). Amplified quenching of MEH-PPV emission is observed with an initial Stern-Volmer constant in excess of 105 M−1. Stern-Volmer plots are nonlinear with two distinct quenching regimes, hinting saturation of NP surfaces with acceptor molecules at some point during titration experiments. Using an assumption that highly efficient quenching of excitons occurs after saturation with acceptors at the NP surfaces, the amount of maximum emission quenching can be compared with a model of exciton diffusion to determine exciton diffusion length. By assuming quenching efficiency above 80%, the measured three dimensional exciton diffusion length is estimated to be 12 ± 1 nm. This result is in the lower region of reported values ranging from 10 to 25 nm in MEH-PPV thin films. Both the derived model and the experimental methodology allow robust measurement of exciton diffusion length for any luminescent conjugated material from which NPs can be prepared.
Spray coating fabrication of organic solar cells bypassing the limit of orthogonal solvents
Authors: Colella Silvia , Mazzeo Marco , Melcarne Giovanna , Carallo Sonia , Ciccarella Giuseppe , Gigli Giuseppe
Published: May 2013

The development of alternative deposition techniques is an important step towards the realization of low cost multilayered organic solar cells. While spin-coating needs orthogonal solvents to avoid an intermixing of stacked layers, thermal evaporation is expensive and not applicable to polymers. We show here how an innovative deposition technique called dry spray-coating may represent a promising way to manufacture bulk-hetero-junction (BHJ) and multilayered solar cells. Using standard materials such as poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester, we achieved efficiency of 2.6% for the BHJ device, while a value of 1.5% was obtained for a bilayer structure using the same solvent for both materials.
Synthesis and incorporation of high quality FeS2 nanoparticles within poly(3-hexylthiophene):Phenyl-C60-butyric acid methyl ester to increase the photosensitivity of composite material
Authors: Layek Animesh , Middya Somnath , Pratim Ray Partha
Published: May 2013

In this study, high quality environment friendly FeS2 nanoparticle was synthesized in hydrothermal route with capping reagent. Band gap energy of FeS2 has been modified and applied in polymer:inorganic nanocomposite. Pyrite structure of FeS2 nanoparticle has been confirmed by different structural characterization techniques. Thermal stability has been studied by thermogravimetric analysis technique. Finally, FeS2 has been introduced within a poly(3-hexylthiophene):Phenyl-C60-butyric acid methyl ester (P3HT:PCBM) matrix at different weight ratios to increase the photosensitivity of the nanocomposite. The composite film of P3HT:PCBM:FeS2 with weight ratio 2:1:0.2 shows highest photosensitivity. Increased photosensitivity has been explained from photoluminescence data.
Compact integrated X-ray intensity and beam position monitor based on rare gas scintillation
Authors: Revesz Peter , Ruff Jacob , Dale Darren , Krawczyk Thomas
Published: May 2013

We have created and tested a compact integrated X-ray beam intensity and position monitor using Ar-gas scintillation. The light generated inside the device's cavity is detected by diametrically opposed PIN diodes located above and below the beam. The intensity is derived from the sum of the top and bottom signals, while the beam position is calculated from the difference-over-sum of the two signals. The device was tested at Cornell High Energy Synchrotron Source with both 17 keV and 59 keV x-rays. For intensity monitoring, the Ar-scintillation monitor performance is comparable to standard ion chambers in terms of precision. As an X-ray beam position monitor the new device response is linear with vertical beam position over a 2 mm span with a precision of 2 μm.
Anomalous change in dielectric constant of CaCu3Ti4O12 under violet-to-ultraviolet irradiation
Authors: Masingboon C. , Eknapakul T. , Suwanwong S. , Buaphet P. , Nakajima H. , Mo S.-K. , Thongbai P. , King P. D. C. , Maensiri S. , Meevasana W.
Published: May 2013

The influence of light illumination on the dielectric constant of CaCu3Ti4O12 (CCTO) polycrystals is studied in this work. When exposed to 405-nm laser light, a reversible enhancement in the room temperature capacitance as high as 22% was observed, suggesting application of light-sensitive capacitance devices. To uncover the microscopic mechanisms mediating this change, we performed electronic structure measurements, using photoemission spectroscopy, and measured the electrical conductivity of the CCTO samples under different conditions of light exposure and oxygen partial pressure. Together, these results suggest that the large capacitance enhancement is driven by oxygen vacancies induced by the irradiation.
Second harmonic generation and enhancement in microfibers and loop resonators
Authors: Gouveia Marcelo A. , Lee Timothy , Ismaeel Rand , Ding Ming , Broderick Neil G. R. , Cordeiro Cristiano M. B. , Brambilla Gilberto
Published: May 2013

We model and experimentally investigate second harmonic generation in silica microfibers and loop resonators, in which the second order nonlinearity arises from the glass-air surface dipole and bulk multipole contributions. In the loop resonator, the recirculation of the pump light on resonance is used to increase the conversion. The effect of the loop parameters, such as coupling and loss, is theoretically studied to determine their influence on the resonance enhancement. Experimentally, microfibers were fabricated with diameters around 0.7 μm to generate the intermodally phase matched second harmonic with an efficiency up to 4.2 × 10−8 when pumped with 5 ns 1.55 μm pulses with a peak power of 90 W. After reconfiguring the microfiber into a 1 mm diameter loop, the efficiency was resonantly enhanced by 5.7 times.
Effect of carbon nanotube persistence length on heat transfer in nanocomposites: A simulation approach
Authors: Bui Khoa , Grady Brian P. , Saha Mrinal C. , Papavassiliou Dimitrios V.
Published: May 2013

Monte Carlo simulations were employed to investigate the effective thermal conductivity (Keff) of multi-walled carbon nanotube-epoxy (MWNT-epoxy) nanocomposites with and without coating the MWNTs with silica. The numerical approach was validated with experimental data and values of the Kapitza resistance for the silica-coated MWNT-epoxy composite were calculated for realistic configurations of the MWNTs. While the Kapitza resistance was found to be 40% smaller than for the case of pristine MWNTs, it was also observed that the effect of persistence length of the MWNT on Keff is as important as the effect of the Kapitza resistance.
Single electron transistors with ultra-thin Au nanowires as a single Coulomb island
Authors: Yoshihira M. , Moriyama S. , Guerin H. , Ochi Y. , Kura H. , Ogawa T. , Sato T. , Maki H.
Published: May 2013

Single electron transistors exhibiting transport properties based on a single Coulomb island have been fabricated using ultra-thin gold nanowires (AuNWs), which are synthesized via a chemical reduction process. The AuNWs are bottom-contacted with source and drain electrodes to avoid damaging the AuNWs under fabrication processes. We investigate the transport properties in the fabricated devices as a function of the bias and gate voltages at room and low temperatures. At 0.23 K, the periodical Coulomb oscillations and diamonds are clearly observed indicating that an individual AuNW acts as a single Coulomb island. These transport properties can be explained by the orthodox Coulomb blockade theory.
An efficient interconnection unit composed of electron-transporting layer/metal/p-doped hole-transporting layer for tandem organic photovoltaics
Authors: Shim Hyun-Sub , Kim Sei-Yong , Whan Kim Ji , Kim Tae-Min , Lee Chang-Heon , Kim Jang-Joo
Published: May 2013

We report an efficient interconnection unit (ICU) consisting of an electron transporting layer/metal/p-doped hole transporting layer (p-HTL) structure for tandem organic photovoltaic (TOPV) cells. The ICU satisfies all the requirements of optical transparency and low voltage loss and for functioning as an optical spacer. The variation of the short circuit current and open circuit voltage (VOC) of the TOPV cells with increasing thickness of the p-HTL in the ICU followed the theoretical predictions, proving that the ICU does not disturb the electrical characteristics of the TOPV cells up to a p-HTL thickness of 100 nm with minimal VOC loss (∼3%).