bluuebunny/crossref_metadata_2025 huggingface dataset:
Intermolecular bromoesterification of conjugated enynes: an efficient synthesis of bromoallenes
Authors: Wang Hao-Yuan , Zhang Wei , Schienebeck Casi M. , Bennett Scott R. , Tang Weiping
Published: March 2014

Highly functionalized bromoallenes were prepared by intermolecular 1,4-bromoesterification of conjugated enynes.
Two 2D sliver complexes with a symmetric and noncentrosymmetric architecture controlled by the metal–ligand ratio
Authors: Wu Lin-Fei , Wang Zhao-Xi , Xue Chao-Chao , Xiao Hong-Ping , Li Ming-Xing
Published: March 2014

By controlling the metal–ligand ratio, we obtained two 2D sliver complexes from a symmetric to noncentrosymmetric architecture based on 2,2′-phosphinico-dibenzoic acid (H3L). The four groups around the phosphorus atom of the L3− ligand connect the Ag(i) ions through different coordination modes to form a noncentrosymmetric complex 2.
Synthesis, structures and luminescent properties of lanthanide coordination polymers involving biphenyl-3,4′,5-tricarboxylate
Authors: Li Xiang-Ying , Lin Zu-Jin , Yang Yan-Yan , Cao Rong
Published: March 2014

A series of lanthanide coordination polymers: {[Ln2(BPT)2(DMF)(H2O)3]∙2DMF∙3H2O}n [Ln = Ce (1), Pr (2) and Eu (3)], {[Ln2(BPT)2(DMA)2(H2O)3]∙0.5DMA∙2.5H2O}n [Ln = La (4), Sm (5), Eu (6) and Tb (7)] and {[Ln(BPT)(DMSO)2]∙H2O}n [Ln = Sm (8) and Nd (9)] have been constructed by biphenyl -3, 4’, 5-tricarboxylate (H3BPT).
CH–π hydrogen bonds in biological macromolecules
Authors: Nishio Motohiro , Umezawa Yoji , Fantini Jacques , Weiss Manfred S. , Chakrabarti Pinak
Published: March 2014

A feature involving short CH–π contacts: a ladder of CH–π hydrogen bonds occurs in the structure of human growth hormone.
How does the dehydration change the host–guest association under homogeneous and heterogeneous conditions?
Authors: Filippini G. , Bonal C. , Malfreyt P.
Published: March 2014

In this study, the thermodynamic properties of association of some inorganic ions (ClO4− and SO42−) with β-cyclodextrins (β-CD) in aqueous solution are determined under both free β-CD and surface confined β-CD conditions using atomistic simulations.
The concept, reality and utility of single-site heterogeneous catalysts (SSHCs)
Authors: Thomas John Meurig
Published: March 2014

The large-pores of this metal–organic framework allow bulky reactants to be catalytically converted at single-site active centres situated at the inner surface.
The influence of applied silica nanoparticles on a bio-renewable castor oil based polyurethane nanocomposite and its physicochemical properties
Authors: Seeni Meera Kamal Mohamed , Murali Sankar Rajavelu , Paul Jaya , Jaisankar Sellamuthu N. , Mandal Asit Baran
Published: March 2014

Bio-renewable castor oil polyurethane–silica nanocomposite films with improved thermal, surface and mechanical properties were prepared. These films find application in biomaterials development.
Hydrogen reversibility of LiBH4–MgH2–Al composites
Authors: Hansen Bjarne R. S. , Ravnsbæk Dorthe B. , Skibsted Jørgen , Jensen Torben R.
Published: March 2014

Numerous intermediates are involved in the decomposition mechanism of LiBH4–MgH2–Al and the cyclic stability is evaluated.
The mechanism of NaFePO4 (de)sodiation determined by in situ X-ray diffraction
Authors: Galceran Montserrat , Saurel Damien , Acebedo Begoña , Roddatis Vladimir V. , Martin Egoitz , Rojo Teófilo , Casas-Cabanas Montse
Published: March 2014

Insight into the mechanism of Na insertion and extraction into FePO4–NaFePO4 based on a detailed in situ X-ray diffraction study, from which interesting new features were identified and analysed.
Octanuclear [NiII4LnIII4] complexes. Synthesis, crystal structures and magnetocaloric properties
Authors: Pasatoiu Traian D. , Ghirri Alberto , Madalan Augustin M. , Affronte Marco , Andruh Marius
Published: March 2014

Slow sorption of atmospheric CO2 yielded a [NiII4GdIII4] complex with a significant magnetocaloric effect in the 1–20 K temperature range.
Microfluidic device (ExoChip) for on-chip isolation, quantification and characterization of circulating exosomes
Authors: Kanwar Shailender Singh , Dunlay Christopher James , Simeone Diane M. , Nagrath Sunitha
Published: March 2014

Microfluidic all-in-one device “ExoChip” for isolation, quantification and analysis of circulatory exosomes: bridging the gap between technology and clinical application.
Local and transient permeation events are associated with local melting of giant liposomes
Authors: Andersen Thomas , Kyrsting Anders , Bendix Poul M.
Published: March 2014

Locally induced lipid phase transitions reveal how protein-free lipid membranes exhibit transient and localized permeation.
Signalling events regulating seed coat development
Authors: Figueiredo Duarte D. , Köhler Claudia
Published: March 2014

The evolution of seeds was a major reason for the rise of angiosperms to ecological dominance. Seeds of angiosperms are composed of three main structures: the embryo, which will give rise to the next generation; the endosperm, a nurturing tissue whose main function is to deliver nutrients from the mother plant to the embryo; and the seed coat (or testa), a tissue that is derived from the maternal integuments and which provides support and protection to the growing embryo. All three seed components need to exchange signals to ensure co-ordinated growth and development. The present review discusses the structure of the seed coat, its interaction with the endosperm, and bidirectional signalling events between endosperm and seed coat that co-ordinate growth of both tissues. Angiosperm seeds are not only of evolutionary significance, but also of major agronomic importance, demanding a thorough understanding of the events governing seed growth and development.
Cavin-1: caveolae-dependent signalling and cardiovascular disease
Authors: Williams Jamie J.L. , Palmer Timothy M.
Published: March 2014

Caveolae are curved lipid raft regions rich in cholesterol and sphingolipids found abundantly in vascular endothelial cells, adipocytes, smooth muscle cells and fibroblasts. They are multifunctional organelles with roles in clathrin-independent endocytosis, cholesterol transport, mechanosensing and signal transduction. Caveolae provide an environment where multiple receptor signalling components are sequestered, clustered and compartmentalized for efficient signal transduction. Many of these receptors, including cytokine signal transducer gp130 (glycoprotein 130), are mediators of chronic inflammation during atherogenesis. Subsequently, disruption of these organelles is associated with a broad range of disease states including cardiovascular disease and cancer. Cavin-1 is an essential peripheral component of caveolae that stabilizes caveolin-1, the main structural/integral membrane protein of caveolae. Caveolin-1 is an essential regulator of eNOS (endothelial nitric oxide synthase) and its disruption leads to endothelial dysfunction which initiates a range of cardiovascular and pulmonary disorders. Although dysfunctional cytokine signalling is also a hallmark of cardiovascular disease, knowledge of caveolae-dependent cytokine signalling is lacking as is the role of cavin-1 independent of caveolae. The present review introduces caveolae, their structural components, the caveolins and cavins, their regulation by cAMP, and their potential role in cardiovascular disease.
The cardioprotective role of small heat-shock protein 20
Authors: Martin Tamara P. , Currie Susan , Baillie George S.
Published: March 2014

The small HSP (heat-shock protein) HSP20 is a molecular chaperone that is transiently up-regulated in response to cellular stress/damage. Although ubiquitously expressed in various tissues, it is most highly expressed in skeletal, cardiac and smooth muscle. Phosphorylation at Ser16 by PKA (cAMP-dependent protein kinase) is essential for HSP20 to confer its protective qualities. HSP20 and its phosphorylation have been implicated in a variety of pathophysiological processes, but most prominently cardiovascular disease. A wealth of knowledge of the importance of HSP20 in contractile function and cardioprotection has been gained over the last decade. The present mini-review highlights more recent findings illustrating the cardioprotective properties of HSP20 and its potential as a therapeutic agent.
Dynamics of adenylate cyclase regulation via heterotrimeric G-proteins
Authors: Milde Markus , Werthmann Ruth C. , von Hayn Kathrin , Bünemann Moritz
Published: March 2014

A wide variety of G-protein-coupled receptors either activate or inhibit ACs (adenylate cyclases), thereby regulating cellular cAMP levels and consequently inducing proper physiological responses. Stimulatory and inhibitory G-proteins interact directly with ACs, whereas Gq-coupled receptors exert their effects primarily via Ca2+. Using the FRET-based cAMP sensor Epac1 (exchange protein directly activated by cAMP 1)–cAMPS (adenosine 3′,5′-cyclic monophosphorothioate), we studied cAMP levels in single living VSMCs (vascular smooth muscle cells) or HUVECs (human umbilical vein endothelial cells) with subsecond temporal resolution. Stimulation of purinergic (VSMCs) or thrombin (HUVECs) receptors rapidly decreased cAMP levels in the presence of the β-adrenergic agonist isoprenaline via a rise in Ca2+ and subsequent inhibition of AC5 and AC6. Specifically in HUVECs, we observed that, in the continuous presence of thrombin, cAMP levels climbed slowly after the initial decline with a delay of a little less than 1 min. The underlying mechanism includes phospholipase A2 activity and cyclo-oxygenase-mediated synthesis of prostaglandins. We studied further the dynamics of the inhibition of ACs via Gi-proteins utilizing FRET imaging to resolve interactions between fluorescently labelled Gi-proteins and AC5. FRET between Gαi1 and AC5 developed at much lower concentration of agonist compared with the overall Gi-protein activity. We found the dissociation of Gαi1 subunits and AC5 to occur slower than the Gi-protein deactivation. This led us to the conclusion that AC5, by binding active Gαi1, interferes with G-protein deactivation and reassembly and thereby might sensitize its own regulation.
Targeting mitochondria to restore failed adaptation to exercise in diabetes
Authors: Geary Kate , Knaub Leslie A. , Schauer Irene E. , Keller Amy C. , Watson Peter A. , Miller Matthew W. , Garat Chrystelle V. , Nadeau Kristen J. , Cree-Green Melanie , Pugazhenthi Subbiah , Regensteiner Judith G. , Klemm Dwight J. , Reusch Jane E.B.
Published: March 2014

Our translational research group focuses on addressing the problem of exercise defects in diabetes with basic research efforts in cell and rodent models and clinical research efforts in subjects with diabetes mellitus. CREB (cAMP-response-element-binding protein) regulates cellular differentiation of neurons, β-cells, adipocytes and smooth muscle cells; it is also a potent survival factor and an upstream regulator of mitochondrial biogenesis. In diabetes and cardiovascular disease, CREB protein content is decreased in the vascular media, and its regulation in aberrant in β-cells, neurons and cardiomyocytes. Loss of CREB content and function leads to decreased vascular target tissue resilience when exposed to stressors such as metabolic, oxidative or sheer stress. This basic research programme set the stage for our central hypothesis that diabetes-mediated CREB dysfunction predisposes the diabetes disease progression and cardiovascular complications. Our clinical research programme revealed that diabetes mellitus leads to defects in functional exercise capacity. Our group has determined that the defects in exercise correlate with insulin resistance, endothelial dysfunction, decreased cardiac perfusion and diastolic dysfunction, slowed muscle perfusion kinetics, decreased muscle perfusion and slowed oxidative phosphorylation. Combined basic and clinical research has defined the relationship between exercise and vascular function with particular emphasis on how the signalling to CREB and eNOS [endothelial NOS (nitric oxide synthase)] regulates tissue perfusion, mitochondrial dynamics, vascular function and exercise capacity. The present review summarizes our current working hypothesis that restoration of eNOS/NOS dysfunction will restore cellular homoeostasis and permit an optimal tissue response to an exercise training intervention.
Methylglyoxal and glyoxalase I in atherosclerosis
Authors: Hanssen Nordin M.J. , Stehouwer Coen D.A. , Schalkwijk Casper G.
Published: March 2014

Cardiovascular disease, caused predominantly by atherosclerotic plaque rupture, remains one of the leading causes of death. However, the mechanism of plaque rupture remains largely unknown. Recent studies have linked high metabolic activity in inflamed atherosclerotic plaques to the development of plaque rupture. AGEs (advanced glycation end-products) are known to be formed as a result of high metabolic activity and are higher in rupture-prone than stable plaques. Furthermore, AGEs seem to be more than mere markers of metabolic activity, as recent studies have elucidated that AGEs and their major precursor, MG (methylglyoxal), may have an important role in the progression of atherosclerosis and plaque rupture. MG can be detoxified by Glo1 (glyoxalase I), thereby preventing the accumulation of MG and MG-derived AGEs. In the present review, data concerning MG, Glo1 and AGEs in the context of plaque phenotype are discussed.
Glyoxalase I (Glo1) and its metabolites in vascular disease
Authors: Wortmann Markus , Peters Andreas S. , Hakimi Maani , Böckler Dittmar , Dihlmann Susanne
Published: March 2014

Glo1 (glyxoalase I) is a cytosolic protein expressed in all mammalian cells. Its physiological function is the detoxification of MG (methylglyoxal), which is a potent precursor of AGEs (advanced glycation end-products). Although the impact of AGEs on different forms of vascular diseases has been intensively investigated, the evidence for the involvement of Glo1 and MG is still scarce. Recently, several studies have provided significant evidence for Glo1 having a protective effect on microvascular complications in diabetic patients, such as retinopathy and nephropathy. Regarding macrovascular complications, especially atherosclerotic lesions, the impact of Glo1 is even less clear. In the present article, we review the latest findings regarding the role of Glo1 and MG in vascular biology and the pathophysiology of micro- and macro-vascular disease.
Insulin, incretins and other growth factors as potential novel treatments for Alzheimer's and Parkinson's diseases
Authors: Hölscher Christian
Published: March 2014

Recently, it has been shown that in patients with AD (Alzheimer's disease) and, to some degree, in patients with PD (Parkinson's disease) insulin signalling is impaired. This finding has initiated a range of research projects that showed remarkable improvements using treatments that initially had been developed to treat diabetes. Pre-clinical studies showed good neuroprotective effects when applying insulin or long-lasting analogues of incretin peptides. In transgenic animal models of AD and PD, analogues of the incretin GLP-1 (glucagon-like peptide 1) prevented neurodegenerative processes and improved neuronal and synaptic functionality in AD and PD. Amyloid plaque load and synaptic loss as well as cognitive impairment had been ameliorated in AD models, and dopaminergic loss of transmission and motor function was reversed in models of PD. On the basis of these promising findings, several clinical trials are being conducted with the first encouraging clinical results being published. In several pilot studies in AD patients, the nasal application of insulin showed encouraging effects on cognition and biomarkers. A pilot study in PD patients testing a GLP-1 receptor agonist that is currently on the market as a treatment for Type 2 diabetes also showed encouraging effects. Several other clinical trials are currently ongoing in AD patients. The present review summarizes the range of neuroprotective effects that these drugs have demonstrated and emphasizes the great promise that this approach has in providing novel treatments that have protective and even restorative properties that no current drug treatment can offer.
Prevention of dicarbonyl-mediated advanced glycation by glyoxalases: implication in skin aging
Authors: Radjei Sabrina , Friguet Bertrand , Nizard Carine , Petropoulos Isabelle
Published: March 2014

Skin aging is the result of intrinsic chronological aging and photoaging, due to UV exposure, that both share important histological modifications and molecular features, including alterations of proteins. One of the main damage is glycation that occurs when reducing sugars react non-enzymatically with proteins. This reaction also happens when the dicarbonyl compounds GO (glyoxal) and MG (methylglyoxal), which are glucose derivatives, react with proteins. These compounds can be detoxified by the glyoxalase system composed of two enzymes, Glo1 (glyoxalase I) and Glo2 (glyoxalase II). The aims of the present mini-review are to briefly summarize our current knowledge of the biological roles of these enzymes in aging and then discuss the relevance of studying the role of glycation and of detoxifying systems in human skin aging.
Assay of methylglyoxal-derived protein and nucleotide AGEs
Authors: Rabbani Naila , Shaheen Fozia , Anwar Attia , Masania Jinit , Thornalley Paul J.
Published: March 2014

Glyoxalase- and methylglyoxal-related research has required the development of quantitative and reliable techniques for the measurement of methylglyoxal-derived glycation adducts of protein and DNA. There are also other glycation adducts, oxidation adducts and nitration adducts of proteins and oxidation adducts of DNA. Proteolysis of protein releases glycation, oxidation and nitration free adducts (glycated, oxidized and nitrated amino acids) in plasma and nuclease digestion of DNA releases glycated and oxidized nucleosides into plasma and other body fluids for excretion in urine. The gold standard method for quantifying these adducts is stable isotopic dilution analysis LC–MS/MS. Protein and DNA adduct residues are determined by assay of enzymatic hydrolysates of protein and DNA extracts prepared using cocktails of proteases and nucleases respectively. Free adducts are determined by analysis of ultrafiltrates of plasma, urine and other physiological fluids. Protein damage markers (13 glycation adducts, five oxidation adducts and 3-nitrotyrosine) and DNA damage markers (three glycation adducts and one oxidation adduct) are quantified using 25 μg of protein, 10 μg of DNA or 5 μl of physiological fluid. Protein and nucleotide AGE (advanced glycation end-product) assay protocols resistant to interferences is described.
Magnetic equivalent circuit modelling of brushless doubly‐fed induction generator
Authors: Gorginpour Hamed , Jandaghi Behzad , Oraee Hashem , Abdi Ehsan
Published: March 2014

The brushless doubly‐fed induction generator (BDFIG) has substantial benefits, which make it an attractive alternative as a wind turbine generator. The aim of this work is to present a nodal‐based magnetic equivalent circuit (MEC) model of the BDFIG which provides performance characteristics and flux density distributions. The model takes into account stator winding distributions, special configuration of rotor bars, slotting effects, teeth saturation, flux fringing and current displacement effects. The real flux tubes are considered for creating an MEC network and calculating its non‐linear elements. A method for simplifying the rotor magnetic network has been applied and Gauss elimination with partial pivoting approach is used to solve the equation system with sparse coefficient matrix. The model parameters are based solely on geometrical data and thus it is an appropriate tool for population‐based design studies instead of computationally intense analysis of the finite element method. The steady‐state results of the proposed model are verified experimentally. The comparisons demonstrate the effectiveness of the proposed model especially when the core is magnetically saturated.
Model predictive control of inverters for both islanded and grid‐connected operations in renewable power generations
Authors: Hu Jiefeng , Zhu Jianguo , Dorrell David G.
Published: March 2014

As the penetration of renewable power generation units connected to the grid increases, high power quality and flexible power regulation have raised much concern. This study proposes a competitive model predictive control strategy for inverters in renewable power generation applications. The controller uses the system model to predict the system behaviour in each sampling interval for each voltage vector, and the most appropriate vector is then chosen according to an optimisation criterion. In islanded mode, the control objectives of the cost function are the α and β components of the voltage so that stable voltage for the local loads can be established. In addition, a fast re‐synchronisation scheme is introduced to achieve smooth grid connection. After connected to the grid, a new prediction scheme is developed to fulfill flexible active and reactive power regulation. Furthermore, a switching frequency reduction scheme is presented to reduce switching losses, which are especially significant when considering efficiency for renewable power generations. The effectiveness of the proposed control strategy was tested by simulation using MATLAB/Simulink and experimentally validated on a laboratory prototype.
Einsatz einer präventiven, epikutanen Unterdrucktherapie (Prevena™) bei offener Korrektur
von Deformitäten der vorderen Brustwand reduziert das Auftreten von
Wundheilungsstörungen
Authors: Simon K. , Schulz-Drost M. , Besendörfer M. , Carbon R. , Schulz-Drost S.
Published: March 2014

Hintergrund: Eingriffe an der vorderen Brustwand können zu Wundheilungsstörungen führen.
Untersucht wird, ob die Anwendung einer präventiven Unterdrucktherapie das Risiko einer
Wundheilungsstörung an der vorderen Brustwand nach offener Brustwandkorrektur reduzieren kann.
Methodik: In einer retrospektiven Vergleichsanalyse von 100 Patienten mit offener
Korrektur einer Trichter- oder Kielbrustdeformität in den Jahren 2010 bis 2012 wurden 50
aufeinanderfolgend behandelte Patienten, deren Wunde 5 Tage postoperativ mittels Prevena™ (KCI
Medizinprodukte GmbH, Wiesbaden) behandelt wurde, mit 50 aufeinanderfolgenden Patienten
verglichen, deren Wunde mit einer OPSITE®-Folie (Smith & Nephew, Hamburg) abgedeckt wurde.
Die Wundnaht erfolgte nach einem Standard, ebenso die Einlage von Redon-Dränagen. Es wurden
daher retrospektiv 2 gleichwertige, repräsentative Patientengruppen gebildet und systematisch
anhand standardisiert erhobener Parameter verglichen. Das Wunddressing wurde in beiden Gruppen
unmittelbar nach dem Wundverschluss aufgebracht und jeweils bis zum 5. postoperativen Tag
belassen. Wundkontrollen erfolgten bei Abnahme des Verbands, bei Entlassung, 6 Wochen und 12
Wochen postoperativ. Zu diesen Zeitpunkten wurde die Wunde auf das Vorliegen von Schwellung,
Rötung, Nässen, Schmerzen und Heilungszeichen untersucht. Gegebenenfalls vorliegende Wundfisteln
oder Dehiszenzen wurden in Lokalisation und Ausdehnung erfasst.
Ergebnisse: In der
Prevena-Gruppe sahen wir 10 % interventionspflichtige Wundheilungsstörungen, in der
OPSITE-Gruppe 24 %. Bei Anwendung der Prevena zeigten einige Patienten umschriebene
Hauterosionen im Bereich des Übergangs Schwamm-Folie. Diese waren jedoch in allen Fällen
innerhalb des Beobachtungszeitraums folgenfrei abgeheilt.
Schlussfolgerungen: Durch
Anwendung einer präventiven Vakuumtherapie konnte retrospektiv eine erhebliche Reduktion der
Rate von Wundheilungsstörungen nach offenen Brustwandkorrekturen erzielt werden. Statistisch war
jedoch kein Signifikanzniveau nachzuweisen (p = 0,074).
Ponderomotive potential and backward Raman scattering in dense quantum plasmas
Authors: Son S.
Published: March 2014

The backward Raman scattering is studied in dense quantum plasmas. The coefficients in the backward Raman scattering is found to be underestimated (overestimated) in the classical theory if the excited Langmuir wave has low-wave vector (high-wave vector). The second-order quantum perturbation theory shows that the second harmonic of the ponderomotive potential arises naturally even in a single particle motion contrary to the classical prediction.
The 700-1500 cm−1 region of the S1 ($\widetilde A{}^1B_2$Ã1B2) state of toluene studied with resonance-enhanced multiphoton ionization (REMPI), zero-kinetic-energy (ZEKE) spectroscopy, and time-resolved slow-electron velocity-map imaging (tr-SEVI) spectroscopy
Authors: Gardner Adrian M. , Green Alistair M. , Tamé-Reyes Victor M. , Reid Katharine L. , Davies Julia A. , Parkes Victoria H. K. , Wright Timothy G.
Published: March 2014

We report (nanosecond) resonance-enhanced multiphoton ionization (REMPI), (nanosecond) zero-kinetic-energy (ZEKE) and (picosecond) time-resolved slow-electron velocity map imaging (tr-SEVI) spectra of fully hydrogenated toluene (Tol-h8) and the deuterated-methyl group isotopologue (α3-Tol-d3). Vibrational assignments are made making use of the activity observed in the ZEKE and tr-SEVI spectra, together with the results from quantum chemical and previous experimental results. Here, we examine the 700–1500 cm−1 region of the REMPI spectrum, extending our previous work on the region ≤700 cm−1. We provide assignments for the majority of the S1 and cation bands observed, and in particular we gain insight regarding a number of regions where vibrations are coupled via Fermi resonance. We also gain insight into intramolecular vibrational redistribution in this molecule.
Effect of molecular flexibility of Lennard-Jones chains on vapor-liquid interfacial properties
Authors: Blas F. J. , Bravo A. I. Moreno-Ventas , Algaba J. , Martínez-Ruiz F. J. , MacDowell L. G.
Published: March 2014

We have determined the interfacial properties of short fully flexible chains formed from tangentially bonded Lennard-Jones monomeric units from direct simulation of the vapor-liquid interface. The results obtained are compared with those corresponding to rigid-linear chains formed from the same chain length, previously determined in the literature [F. J. Blas, A. I. M.-V. Bravo, J. M. Míguez, M. M. Piñeiro, and L. G. MacDowell, J. Chem. Phys. 137, 084706 (2012)]. The full long-range tails of the potential are accounted for by means of an improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 129, 6264 (2006)] proposed recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2008)] valid for spherical as well as for rigid and flexible molecular systems. Three different model systems comprising of 3, 5, and 6 monomers per molecule are considered. The simulations are performed in the canonical ensemble, and the vapor-liquid interfacial tension is evaluated using the test-area method. In addition to the surface tension, we also obtained density profiles, coexistence densities, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the chain length and rigidity on these properties. According to our results, the main effect of increasing the chain length (at fixed temperature) is to sharpen the vapor-liquid interface and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness decreases and the surface tension increases as the molecular chains get longer. Comparison between predictions for fully flexible and rigid-linear chains, formed by the same number of monomeric units, indicates that the main effects of increasing the flexibility, i.e., passing from a rigid-linear to a fully flexible chain, are: (a) to decrease the difference between the liquid and vapor densities; (b) to decrease the critical temperature and to increase the critical density; (c) to smooth the density profiles along the interfacial region; (d) to increase the interfacial thickness; and (e) to decrease the vapor-liquid surface tension.
Interaction for solitary waves in coasting charged particle beams
Authors: Liu Shi-Wei , Qi Xin , Han Jiu-Ning , Hong Xue-Ren , Shi Yu-Ren , Duan Wen-shan , Yang Lei
Published: March 2014

By using the extended Poincare-Lighthill-Kuo perturbation method, the collision of solitary waves in a coasting charged particle beams is studied. The results show that the system admits a solution with two solitary waves, which move in opposite directions and can be described by two Korteweg-deVries equation in small-amplitude limit. The collision of two solitary waves is elastic, and after the interaction they preserve their original properties. Then the weak phase shift in traveling direction of collision between two solitary waves is derived explicitly.
On the gauge features of gravity on a Lie algebroid structure
Authors: Fabi S. , Harms B. , Hou S.
Published: March 2014

We present the geometric formulation of gravity based on the mathematical structure of a Lie Algebroid. We show that this framework provides the geometrical setting to describe the gauge propriety of gravity.
On “The conformal metric structure of geometrothermodynamics”: Generalizations
Authors: Azreg-Aïnou Mustapha
Published: March 2014

We show that the range of applicability of the change of representation formula derived by Bravetti et al. [J. Math. Phys. 54, 033513 (2013)] is very narrow and extend it to include all physical applications, particularly, applications to black hole thermodynamics, cosmology, and fluid thermodynamics.
Vapor bubble nucleation by rubbing surfaces: Molecular dynamics simulations
Authors: Ito Takahiro , Lhuissier Henri , Wildeman Sander , Lohse Detlef
Published: March 2014

We propose a new mechanism for bubble nucleation triggered by the rubbing of solid surfaces immersed in a liquid, in which the fluid molecules squeezed between the solids are released with high kinetic energy into the bulk of the liquid, resulting in the nucleation of a vapor bubble. Molecular dynamics simulations with a superheated Lennard-Jones fluid are used to evidence this mechanism. Nucleation is observed at the release of the squeezed molecules, for squeezing pressures above a threshold value and for all the relative velocities between the solids that we investigate. We show that the total kinetic energy of the released molecules for a single release event is proportional to the number of molecules released, which depends on the squeezing pressure, but is independent of the velocity.
Photoelectron imaging and theoretical study on the structure and chemical binding of the mixed-ligand M(I) complexes, [HMSH]− (M = Cu, Ag, and Au)
Authors: Qin Zhengbo , Liu Zhiling , Cong Ran , Xie Hua , Tang Zichao , Fan Hongjun
Published: March 2014

We have reported a combined photoelectron imaging and theoretical study on gaseous mixed-ligand M(I) complexes of [HMSH]− (M = Cu, Ag, and Au). With the aid of Franck-Condon simulations, vibrationally resolved photoelectron spectra yield accurate electron affinities of 3.269(6), 3.669(10), and 3.591(6) eV for [HCuSH], [HAgSH], and [HAuSH], respectively. And low-frequency modes are observed: 368(12) cm−1 for [HCuSH], 286(12) cm−1 for [HAgSH], and 327(12) cm−1 for [HAuSH], respectively. Extensive theoretical calculations are performed to aid in the spectral assignments and the calculated values agree well with the experimental observations. Although the S and H atoms have little discrepancy in electronegativity (2.20 for H and 2.54 for S), distinct bonding properties are demonstrated between H–M and M–S bond. It is revealed that there exists significant ionic bonding between M–S in [HMSH]− (M = Cu, Ag, and Au), while a gradual transition from ionic behavior between H–Cu in [HCuSH]− to quite strong covalent bonding between H–Au in [HAuSH]−, supported by a variety of chemical bonding analyses.
New potassium-sodium niobate lead-free piezoceramic: Giant-d33 vs. sintering temperature
Authors: Wu Jiagang , Wang Xiaopeng , Cheng Xiaojing , Zheng Ting , Zhang Binyu , Xiao Dingquan , Zhu Jianguo , Lou Xiaojie
Published: March 2014

The objective of this work is to achieve a giant piezoelectric constant in (K,Na)NbO3-based lead-free ceramics, and then 0.96K0.46Na0.54Nb0.95Sb0.05O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 lead-free piezoceramics were designed and prepared by optimizing the sintering temperature (TS). The rhombohedral-tetragonal phase boundary is found in the ceramics sintered at 1070 ∼ 1105 °C and is suppressed when sintered at low TS of 1060 ∼ 1065 °C. The threshold for TS is 1070 °C in terms of their ferroelectric and piezoelectric properties owing to the difference in the phase boundary and the microstructure, and a large d33 of 388 ∼ 465 pC/N could be attained in a wide TS range of 1070 ∼ 1105 °C, benefiting their practical applications because of broad TS. More interestingly, the ceramic sintered at 1075 °C has a giant d33 of ∼465 pC/N. We think that such a giant d33 of this material system can benefit the development of (K,Na)NbO3-based piezoceramics.
Communication: An N-body solution to the problem of Fock exchange
Authors: Challacombe Matt , Bock Nicolas
Published: March 2014

We report an N-Body approach to computing the Fock exchange matrix with and without permutational symmetry. The method achieves an O(NlgN) computational complexity through an embedded metric-query, allowing hierarchical application of direct SCF criteria. The advantages of permutational symmetry are found to be 4-fold for small systems, but decreasing with increasing system size and/or more permissive neglect criteria. This work sets the stage for: (1) the introduction of range queries in multi-level multipole schemes for rank reduction, and (2) recursive task parallelism.
Molecular dynamics simulations of wetting behavior of water droplets on polytetrafluorethylene surfaces
Authors: Chen Shuai , Wang Jiadao , Ma Tianbao , Chen Darong
Published: March 2014

Molecular dynamics simulations are performed to simulate the wetting behavior of nanosized water droplets on flat and pillar polytetrafluorethylene surfaces. The results show that the cutoff of the Lennard–Jones (LJ) potential has a large effect on the simulated value of the contact angle and some suggestions are given on how to choose an appropriate cutoff. On flat surfaces, the contact angle is independent of the size of the water droplet, which was determined by the energy parameters of the LJ potential. Furthermore, on pillar surfaces, two different equilibrium states are present: wetted contact and cross contact. For the wetted contact state, the contact angle increases with increasing droplet size and pillar size within a certain range. However, for the cross contact state, the contact angle and droplet size are uncorrelated, which results from the layering and structuring of molecules after their penetration into the hollows between pillars. However, additional simulations show that the final state depends on the initial geometry and the cross contact state is a metastable wetting state.
The α→ϵ phase transition in iron at strain rates up to ∼109 s−1
Authors: Crowhurst Jonathan C. , Reed Bryan W. , Armstrong Michael R. , Radousky Harry B. , Carter Jeffrey A. , Swift Damian C. , Zaug Joseph M. , Minich Roger W. , Teslich Nick E. , Kumar Mukul
Published: March 2014

We have used a table-top scale laser to dynamically compress iron at strain rates in excess of 109 s−1. Using an embedded ultrafast interferometer, we have measured corresponding free surface histories with a time resolution of approximately 10 ps. We have analyzed the surface histories using a method that accounts for nonsteady wave propagation and time-dependent material behavior. We show that at these strain rates, the α→ϵ polymorphic transition begins within 100 ps after an initial very large (∼10 GPa) and mostly elastic compression and appears largely complete within a similar time thereafter. The corresponding deviatoric stress before the transition begins can exceed 3 GPa, while the transition stress itself is up to 25 GPa, nearly twice the value measured at low strain rates. We use these results to propose a systematic variation with loading time of the normal-stress/relative-volume curve followed by iron during rapid compression.
Formation of perovskite BiFeO3(001) films on refined Pt(111) electrode layer with reduced thickness on glass substrates
Authors: Chang H. W. , Yuan F. T. , Tien S. H. , Tu K. T. , Wang C. R. , Jen S. U.
Published: March 2014

Structure and ferroelectric properties of multiferroic BiFeO3 (001) films grown on Pt(111) buffer layer with thicknesses of 5–50 nm on glass substrate at 500 °C have been studied. (001) texture of the perovskite BiFeO3 (BFO) could be developed. Grain size and morphology of the BFO(001) films were closely related to those of Pt electrode although no epitaxial growth was evidenced. The optimized BFO layer which exhibited the ferroelectric performance comparable to those with SrRuO3 under layer could be achieved in the samples with Pt thickness in the range of 10 to 20 nm. Different from the polycrystalline BFO/SrRuO3 films, large grain size for 50-nm-thick Pt underlayer causes degeneration of both the ferroelectric properties and the (001)-texture due to the formation of the secondary B2O3 phase. On the other hand, reducing Pt thickness to 5 nm resulted in the induction of the pinholes and thus the increase of the leakage current density. The presented results reveal that a smooth interface between the Pt electrode and BFO layer is essential to achieve good ferroelectric properties.
Pressure-driven reconnection and quasi periodical oscillations in plasmas
Authors: Paccagnella R.
Published: March 2014

This paper presents a model for an ohmically heated plasma in which a feedback exists between thermal conduction and transport, on one side, and the magneto-hydro-dynamical stability of the system, on the other side. In presence of a reconnection threshold for the magnetic field, a variety of periodical or quasi periodical oscillations for the physical quantities describing the system are evidenced. The model is employed to interpret the observed quasi periodical oscillations of electron temperature and perturbed magnetic field around the so called “Single Helical” state in the reversed field pinch, but its relevance for other periodical phenomena observed in magnetic confinement systems, especially in tokamaks, is suggested.
Stereoscopy of dust density waves under microgravity: Velocity distributions and phase-resolved single-particle analysis
Authors: Himpel Michael , Bockwoldt Tim , Killer Carsten , Ole Menzel Kristoffer , Piel Alexander , Melzer André
Published: March 2014

Experiments on dust-density waves have been performed in dusty plasmas under the microgravity conditions of parabolic flights. Three-dimensional measurements of a dust density wave on a single particle level are presented. The dust particles have been tracked for many oscillation periods. A Hilbert analysis is applied to obtain trajectory parameters such as oscillation amplitude and three-dimensional velocity amplitude. While the transverse motion is found to be thermal, the velocity distribution in wave propagation direction can be explained by harmonic oscillations with added Gaussian (thermal) noise. Additionally, it is shown that the wave properties can be reconstructed by means of a pseudo-stroboscopic approach. Finally, the energy dissipation mechanism from the kinetic oscillation energy to thermal motion is discussed and presented using phase-resolved analysis.
Microscopic model of domain wall motion
Authors: Leschhorn Andreas , Djoumbou Stephane , Kliem Herbert
Published: March 2014

Polarization switching is simulated using a model based on a sequence of single dipole flips. The single dipole flips are assumed to be thermally activated with transition rates depending on the local field. The time to switch a single dipole depends on the deterministic transition rate and on a probabilistic factor. In each step, the dipole with the shortest flip time is switched. We investigate one dimensional dipole chains as well as two and three dimensional systems based on the barium titanate structure that comprises single charges fluctuating in double well potentials and induced dipoles. The two and three dimensional simulations yield intrinsic dead layers close to the electrodes that can not be switched even in very strong fields. These non switchable layers are nuclei for the domain wall motion and thus nuclei for the switching process. The switching time of the system decreases faster than exponential for low fields with increasing field. This decrease slows down for higher fields. Furthermore, we found intrinsic dead layers around a defect.
Investigations on magnetostatic interactions among CoFeB layers with perpendicular anisotropy in [Ta/CoFeB/MgO]N multilayers
Authors: Hao Liang , Cao Jiangwei , Liu Mingfeng , Dang Honggang , Jin Tianli , Wang Ying , Wei Fulin , Wei Dan
Published: March 2014

The magnetostatic interactions among CoFeB layers with perpendicular anisotropy are studied in [Ta/CoFeB/MgO]N multilayers by measured loops, magnetic domains, and a simple model. With increasing repeat number N or decreasing separation thickness d between adjacent CoFeB layers, higher magnetostatic interaction among CoFeB layers results in bow-tie shape perpendicular loops and shrinking of domain size at remanence state. The measured nucleation field Hn of bow-tie shape perpendicular loops can be explained by a simple theoretical model including the intralayer and interlayer magnetostatic interactions among CoFeB layers with a certain domain size.
Damp and dry heat degradation of thermal oxide passivation of p+ silicon
Authors: Thomson Andrew , Gardner Matthew , McIntosh Keith , Shalav Avi , Bullock James
Published: March 2014

Thermal SiO2 passivates both moderately and heavily doped silicon surfaces irrespective of the dopant type, which is advantageous in high-efficiency solar cell designs. Commercial photovoltaic cells are submitted to accelerated ageing tests, such as damp-heat exposure, to ensure they maintain their performance for at least 20 yr. We find damp-heat exposure causes a severe and rapid degradation of thermal SiO2 passivation on p+ silicon surfaces. The reaction is so severe that the diffused-region recombination in the degraded state is limited by the diffusion of minority carriers to the Si–SiO2 interface not the density of interface defects Dit. Certainly, this effect renders the thermal-oxide passivation useless if employed on a solar cell. To study the cause of the degradation, we also test the effects of storage in dry heat and room ambient conditions. Examination of the rate of degradation in the tested storage conditions in comparison with modelled diffusion of moisture in SiO2, we find a significant correlation between the time dependent J0e and moisture supplied to the interface, leading us to the conclusion that moisture ingression and subsequent reaction at the SiO2–Si interface are the cause of both damp-heat and room- ambient degradation.
Superferrimagnetism in hard Nd-Fe-B thick films, an original concept for coercivity enhancement
Authors: Akdogan O. , Dobrynin A. , Le Roy D. , Dempsey N. M. , Givord D.
Published: March 2014

In a number of applications (automotive, wind generators), RFeB magnets are parts of systems which operate at temperatures in the range of 160 °C–180 °C. At these high temperatures, coercivity is preserved by substituting Dy atoms for a part of the Nd ones. The enhanced coercivity obtained may be associated to the high magnetocrystalline anisotropy of Dy atoms, which diffuse into the R2Fe14B phase. The introduction of Dy, however, induces a reduction in the remanent magnetization. Furthermore, Dy is an expensive and strategic material. In this study, we explore a radically different approach to coercivity. A magnetic layer is deposited at the surface of the hard grains, this layer being exchange coupled to the main hard phase in a way that its magnetization is antiparallel to it. Under an applied field that tends to reverse the main phase magnetization, the surface layer, the magnetization of which is along the field, works against reversal. This is the concept of superferrimagnetism. In order to test its impact on the coercivity of real systems, magnetically hard thick films of NdFeB have been sandwiched between thin layers of Gd/Fe, which were transformed to GdFe2 upon annealing. Coercivity enhancement was achieved compared to a reference NdFeB single layer.
Single to quadruple quantum dots with tunable tunnel couplings
Authors: Takakura T. , Noiri A. , Obata T. , Otsuka T. , Yoneda J. , Yoshida K. , Tarucha S.
Published: March 2014

We prepare a gate-defined quadruple quantum dot to study the gate-tunability of single to quadruple quantum dots with finite inter-dot tunnel couplings. The measured charging energies of various double dots suggest that the dot size is governed by the gate geometry. For the triple and quadruple dots, we study the gate-tunable inter-dot tunnel couplings. For the triple dot, we find that the effective tunnel coupling between side dots significantly depends on the alignment of the center dot potential. These results imply that the present quadruple dot has a gate performance relevant for implementing spin-based four-qubits with controllable exchange couplings.
Recovery of complex valued objects from two-point intensity correlation measurement
Authors: Kumar Singh Rakesh , V. Vinu R. , Sharma M. Anandraj
Published: March 2014

We propose and experimentally demonstrate a technique for the recovery of the wavefront from spatially fluctuating fields using the two point intensity correlation, i.e., fourth order correlation. Assuming spatial ergodicity and Gaussian statistics for the speckle field, we connect the fourth order correlation to the modulus of the corresponding second order correlation. The idea is to retrieve the complex coherence function and consequently the wavefront using the off-axis holography. Application of this technique is demonstrated in the reconstruction of complex field of the object lying behind a weak scatterer. Experimental results of recovery of the complex field of phase objects “vortices” with three values of topological charges are presented.
Note: A simple charge neutralization method for measuring the secondary electron yield of insulators
Authors: Weng Ming , Cao Meng , Zhao Hong-Juan , Zhang Hai-Bo
Published: March 2014

We report on a simple and effective charge neutralization method for measuring the total electron-induced secondary electron yield of insulators in a measurement system with a single pulsed electron gun. In this method, the secondary electron collector is negatively biased with respect to the sample to force some emitted secondary electrons to return to the sample surface and therefore to neutralize positive charges accumulated in the sample during the previous measurement. The adequate negative bias is determined and the equilibrium state of negative charging is discussed. The efficacy of the method is demonstrated by the measured electron yields in the cases with and without charge neutralization and by comparison with existing electron yield data of polyimide.
Induced spin-polarization of EuS at room temperature in Ni/EuS multilayers
Authors: Poulopoulos P. , Goschew A. , Kapaklis V. , Wolff M. , Delimitis A. , Wilhelm F. , Rogalev A. , Pappas S. D. , Straub A. , Fumagalli P.
Published: March 2014

Ni/EuS multilayers with excellent multilayer sequencing are deposited via e-beam evaporation on the native oxide of Si(100) wafers at 4 × 10−9 millibars. The samples have very small surface and interface roughness and show sharp interfaces. Ni layers are nanocrystalline 4–8 nm thick and EuS layers are 2–4 nm thick and are either amorphous or nanocrystalline. Unlike for Co/EuS multilayers, all Eu ions are in divalent (ferromagnetic) state. We show a direct antiferromagnetic coupling between EuS and Ni layers. At room temperature, the EuS layers are spin-polarized due to the proximity of Ni. Therefore, Ni/EuS is a candidate for room-temperature spintronics applications.