bluuebunny/crossref_metadata_2025 huggingface dataset:
DASH-Like Diets High in Protein or Monounsaturated Fats Improve Metabolic Syndrome and Calculated Vascular Risk
Authors: Root Martin M. , Dawson Hannah R.
Published: July 2014

Weight-loss diets with varying proportions of macronutrients have had varying effects on weight loss, and components of metabolic syndrome and risk factors for vascular diseases. However, little work has examined the effect of weight-neutral dietary changes in macronutrients on these factors. This is an investigation using the OMNI Heart datasets available from the NHLBI BioLINCC program. This study compared a DASH-like diet high in carbohydrates with similar diets high in protein and high in unsaturated fats. Measures of metabolic syndrome, except waist, and measures of risk factors for vascular diseases were taken at the end of each dietary period. All 3 diets significantly lowered the number of metabolic syndrome components (p ≤ 0.002) with a standardized measure of changes in metabolic syndrome components, suggesting that the high-protein, high-fat diet was most efficacious overall (p = 0.035). All 3 diets lowered a calculated 10-year risk of cardiovascular disease, with the high-protein and unsaturated fat diet being the most efficacious (p < 0.001). Only the unsaturated fat diet showed a slightly decreased calculated 9-year risk of diabetes (p = 0.11). Of the 3 weight-neutral diets, those high in protein and unsaturated fats appeared partially or wholly most beneficial.
Consumption of Model Maillard Reaction Products has no Significant Impact on Ca and Mg Retention or on Tissue Distribution in Rats
Authors: Roncero-Ramos Irene , Pastoriza Silvia , Pilar Navarro M. , Delgado-Andrade Cristina
Published: July 2014

Our aim was to analyze the influence of the prolonged consumption of Maillard reaction prod-ucts (MRPs) from the glucose-lysine model system, on calcium and magnesium bioavailability and on tissue distribution in female rats. A long-term study (88 days) was conducted, in which two groups of rats (n = 12) were fed either a Control diet or one including 3 % glucose-lysine MRPs (GL90 diet). During the experimental period, the global balance was determined; calcium apparent absorption, retention, and bioavailability were stable after consumption of the assayed MRPs (37 % and 38 % for the Control and GL90 groups, respectively). Consequently, there was no change in calcium tissue distribution. During the final week, an additional balance was performed, following urine and feces collection, which showed calcium bioavailability to be stable. During the same period, magnesium apparent absorption and retention increased, leading to higher digestibility and bioavailability. However, these variations could be isolated events of little significance, since overall there were no variations in magnesium body content or retention (73 mg and 75 mg for the Control and GL90 groups, respectively). This conclusion was supported by the stability of the magnesium content and its concentration in the organs. These findings are in line with those of previous studies, which have reported the low affinity of these metals to form MRP complexes.
Venous thromboembolism and cancer: pathophysiology and incidence
Authors: Stricker Hans
Published: July 2014

A relationship between tumor and thrombosis is well known. This review covers the aspect of incidence and pathophysio-logy of cancer-related thromboembolism. Cancer patients have an up to 7 % risk of developing venous thrombosis, partly because they are subject to various circumstantial risk factors such as surgical interventions, immobilization or drugs during their illness. On the other hand, tumors frequently generate a prothrombotic state, which may remain without clinical manifestation or result in anticoagulant-resistent venous thromboembolism. Recently discovered thrombosis-generating mechanisms could help to classify patients in categories with high and low thrombotic risk, which will allow tailored prophylactic and therapeutic interventions.
Das Triptychon in der Kunsttherapie
Authors: Ebersberger Sabine
Published: July 2014

Der vorliegende Beitrag widmet sich dem Triptychon als therapeutische Methode in der Kunsttherapie. Triptychen sind dreiteilige Gemälde, die als sogenannte Flügelaltäre im 15. und 16. Jahrhundert Bekanntheit erlangten. In der Auseinandersetzung mit den therapeutischen Wirkfaktoren (vgl. Grawe, 2000 ; 2004 ) diskutiert der Beitrag die methodischen Stärken des Triptychons als Bildformat und zeigt auf, wie diese in der kunsttherapeutischen Arbeit praktisch nutzbar gemacht werden können. Exemplarische Bildbeispiele verdeutlichen diese Methode.
Hat Expressives Schreiben über eine positiv imaginierte Zukunft Einfluss auf Affekt, Copingstrategien und Selbstwirksamkeit?
Authors: Heimes Silke
Published: July 2014

Das Expressive Schreiben (ES) hat sich in verschiedenen Untersuchungen als hilfreich bei der Verarbeitung belastender Ereignisse erwiesen und es haben sich mehr oder weniger deutliche positive Auswirkungen auf den psychologischen und physiologischen Gesundheitszustand gezeigt. Zunehmend beschäftigen sich Wissenschaftler mit der Frage, ob das ES bei der Formulierung von Lebenszielen zur Verbesserung von Selbstwirksamkeit und Affekt und als Copingstrategie geeignet sein könnte. 31 Studierende der Kunsttherapie und des Coachings wurden randomisiert zwei Gruppen zugeteilt, die beide an drei aufeinanderfolgenden Tagen für zwanzig Minuten entweder über eine positiv imaginierte Zukunft oder ein neutrales Thema schrieben. Untersucht wurden über einen Zeitraum von acht Wochen der positive und negative Affekt (PANAS), die Copingfähigkeiten (COPE) und die Selbstwirksamkeitserwartungen (SWE). In der Experimentalgruppe (EG) kam es nach der Schreibintervention zu einer Zunahme positiver Affekte im Vergleich zu den Ausgangswerten und zur Kontrollgruppe (KG), der sich im Follow-up allerdings verlor. In beiden Gruppen hatte das Schreiben keinen signifikanten Einfluss auf den negativen Affekt, die Copingfähigkeiten und die Selbstwirksamkeitserwartung. Schreiben über eine positiv imaginierte Zukunft vermag den positiven Affekt kurzzeitig zu steigern. Zur langfristigen Stimmungsverbesserung, einer Verbesserung der Copingfähigkeiten und einer Zunahme der Selbstwirksamkeitserwartung bedarf es möglicherweise einer längerdauernden Intervention und eines längeren Nachbeobachtungszeitraums.
Crystalline Silicon Solar Cells with High Efficiency
Authors: Glunz Stefan W.
Published: July 2014

Since the early days of photovoltaics in the 1950s, crystalline silicon solar cells have been the workhorse of this strongly growing industry. Since then great progress has been achieved in decreasing production costs from hundreds of US dollars per Wp down to values well below $1/Wp. Also the technology itself has been strongly improved, as reflected by increasing cell efficiencies in research and production. The notorious 20% hurdle, exceeded only by a small number of companies a few years ago, is now cleared by more and more companies. This chapter gives an overview of the exciting technological developments in research and production. A loss analysis is used to categorize the different cell structures and technologies such as selective emitters, dielectric rear passivation, p-type versus n-type silicon, back-contact structures, heterojunctions and passivated contacts.
Thin-film Photovoltaics Based on Earth-abundant Materials
Authors: Colombara Diego , Dale Phillip , Peter Laurence , Scragg Jonathan , Siebentritt Susanne
Published: July 2014

At some stage in the near future, the rapid expansion of photovoltaic solar energy conversion based on thin films of semiconductors such as cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS) could become subject to constraints arising from materials availability and security. For this reason, the development of alternative PV technologies based on earth-abundant elements has become a research priority. This chapter deals with a range of compound semiconductors that could be used to replace CdTe or CIGS as the light-absorbing layer in thin film solar cells. Because this is a rapidly expanding field, the authors have chosen to place the main emphasis on important fundamental aspects and emerging issues rather than just on device performance. The highly promising kesterite copper zinc tin sulfide/selenide (CZTS(Se)) is discussed in detail in order to illustrate the importance of phase equilibria and thermodynamics when considering the quaternary systems that are alternatives to CIGS. The chapter continues with an in depth discussion of the current state of understanding of the electronic properties of CZTS(Se) before reviewing the different synthetic methods that are being used to prepare kesterite layers for devices. The approach taken by the authors clearly demonstrates the central importance of thermodynamics and kinetics in understanding the formation and thermal stability of CZTS(Se) layers. After a short section on the most important opto-electronic properties of absorber layers, the chapter concludes with a comprehensive survey of a range of other potential absorber materials such as pyrite (FeS2), tin sulfide (SnS), copper tin sulfide (Cu2SnS3) and the copper bismuth/antimony sulfide family.
Quantum Confined Semiconductors for Enhancing Solar Photoconversion through Multiple Exciton Generation
Authors: Beard Matthew C. , Ip Alexander H. , Luther Joseph M. , Sargent Edward H. , Nozik Arthur J.
Published: July 2014

Quantum-confined semiconductor nanostructures that have at least one dimension small enough to confine the wavefunction of an electron to a size comparable or less that its Bohr radius provide new ways to control solar energy conversion not achievable in thin film or bulk semiconductors. The nanostructures are synthesized in solution-phase chemical reactions, producing stable colloidal solutions, where the reaction conditions can be modified to produce a variety of shapes, compositions, and structures with well-controlled size. If the semiconductor nanostructure is confined in one dimension, quantum films, wells, or discs are produced. Quantum wires or rods (QRs) result from two-dimensional confinement, and quantum dots (QDs) are three-dimensionally confined nanostructure. Combining two or more semiconductors either as alloys or as nano-heterostructures allows for further control over energy flow. There are various strategies to incorporate these novel structures into suitable solar conversion systems and some of these have the potential to convert sunlight more efficiently than the Shockley–Queisser (S-Q) limit of ∼33% and thus may become viable third generation photovoltaic (TGPV) cell architectures. Here we review two such approaches. (1) Multiple exciton generation (MEG) is a process where absorption of one high-energy photon produces multiple charge carriers available for power generation and has recently been observed in PbSe QD-based solar cells demonstrating that one of the tenets of the SQ limit can be overcome. (2) Solution processed multi-junction QD-based solar cells.
Triplet–triplet Annihilation Up-conversion
Authors: Schmidt Timothy W. , Tayebjee Murad J. Y.
Published: July 2014

In this chapter we outline how solar cells may be enhanced by photochemical up-conversion brought about by triplet–triplet annihilation. We begin by introducing the photon–ratchet model of a quantum photovoltaic energy convertor. The Shockley–Queisser limit is determined, and the model is extended to include a generalized photon up-convertor. The photochemistry underpinning the triplet–triplet annihilation up-conversion (TTA-UC) scheme is described and efficiency considerations are discussed. Applications of TTA-UC to thin-film photovoltaic devices are described and the figure of merit for these systems is explained. The chapter concludes with a discussion of the prospects of the efficient deployment of this technology.
Room temperature phosphorescence of the biocompatible B2O3/SiO2 nanocomposite and its application for cellular imaging
Authors: Zhuang Zhenjing , Zhang Junping , Zhang Manman , Xiao Dan
Published: July 2014

Highly emissive broadband phosphors of B2O3/SiO2 nanoparticles were synthesized and used as optical probes for live cell imaging.
Light-reactive dextran gels with immobilized guidance cues for directed neurite growth in 3D models
Authors: Horn-Ranney Elaine L. , Khoshakhlagh Parastoo , Kaiga Julie W. , Moore Michael J.
Published: July 2014

Immobilized NT-3 enhanced DRG neurite growth while Sema3A strongly repelled it,versusneutravidin controls, in a hydrogel choice point model.
A high-throughput polymer microarray approach for identifying defined substrates for mesenchymal stem cells
Authors: Duffy Cairnan R. E. , Zhang Rong , How Siew-Eng , Lilienkampf Annamaria , Tourniaire Guilhem , Hu Wei , West Christopher C. , de Sousa Paul , Bradley Mark
Published: July 2014

Defined polymer substrates supported the growth of mesenchymal stem cells in long-term culture while maintaining their phenotype and lineage potential.
Direct oxidative nitration of aromatic sulfonamides under mild conditions
Authors: Li Ying-Xiu , Li Lian-Hua , Yang Yan-Fang , Hua Hui-Liang , Yan Xiao-Biao , Zhao Lian-Biao , Zhang Jin-Bang , Ji Fa-Jin , Liang Yong-Min
Published: July 2014

This efficient reaction proceeds under very mild conditions with low cost nitration reagents and can be applied in gram-scale preparation.
Guest control of structure in porous organic cages
Authors: Little Marc A. , Chong Samantha Y. , Schmidtmann Marc , Hasell Tom , Cooper Andrew I.
Published: July 2014

Two porous organic cages with different thermodynamic polymorphs were induced by co-solvents to interchange their crystal packing modes, thus achieving guest-mediated control over solid-state porosity.
A combined crossed molecular beams and ab initio investigation on the formation of vinylsulfidoboron (C2H311B32S)
Authors: Yang Tao , Dangi Beni B. , Parker Dorian S. N. , Kaiser Ralf I. , An Yi , Chang Agnes H. H.
Published: July 2014

Bimolecular gas phase formation of vinylsulfidoboron (C2H311B32S) under single collision conditions.
Diffusive and rotational dynamics of condensed n-H2confined in MCM-41
Authors: Prisk T. R. , Bryan M. S. , Sokol P. E.
Published: July 2014

In this paper, we report an inelastic neutron scattering study of liquid and solidn-H2confined within MCM-41.
An irresolute linker: separation, and structural and spectroscopic characterization of the two linkage isomers of a Ru(ii)-(2-(2′-pyridyl)pyrimidine-4-carboxylic acid) complex
Authors: Iengo E. , Demitri N. , Balducci G. , Alessio E.
Published: July 2014

For the first time the two linkage isomers of a Ru(ii) complex with 2-(2′-pyridyl)pyrimidine-4-carboxylic acid (cppH) have been fully characterized individually, both in solution and in the solid state.
A rational design of carbon-supported dispersive Pt-based octahedra as efficient oxygen reduction reaction catalysts
Authors: Huang Xiaoqing , Zhao Zipeng , Chen Yu , Zhu Enbo , Li Mufan , Duan Xiangfeng , Huang Yu
Published: July 2014

Highly dispersive carbon-supported octahedral Pt-based catalysts were prepared by an efficient one-pot synthetic strategy without using any bulky capping agents and were demonstrated as promising catalysts for oxygen reduction reaction (ORR).
Mechanisms for CO oxidation on Fe(iii)–OH–Pt interface: a DFT study
Authors: Zhao Yun , Chen Guangxu , Zheng Nanfeng , Fu Gang
Published: July 2014

The full catalytic cycle that involves the oxidation of two CO molecules is investigated here by using periodic density functional calculations. To simulate the nature of Fe(OH)x/Pt nanoparticles, three possible structural models, i.e., Fe(OH)x/Pt(111), Fe(OH)x/Pt(332) and Fe(OH)x/Pt(322), are built. We demonstrate that Fe(iii)–OH–Pt stepped sites readily react with CO adsorbed nearby to directly yield CO2 and simultaneously produce coordinatively unsaturated iron sites for O2 activation. By contrast, the created interfacial vacancy on Fe(OH)x/Pt(111) prefers to adsorb CO rather than O2, thus inhabiting the catalytic cycles of CO oxidation. We suggest that such structure sensitivity can be understood in terms of the bond strengths of Fe(iii)–OH.
Influence of precursor type on non-toxic hybrid inks for high-efficiency Cu2ZnSnS4 thin-film solar cells
Authors: Kim Kyujin , Kim Inhyuk , Oh Yunjung , Lee Daehee , Woo Kyoohee , Jeong Sunho , Moon Jooho
Published: July 2014

A Cu2ZnSnS4 solar cell with an efficiency of 8.17% was fabricated using a non-toxic solvent-based hybrid-ink without the involvement of a complex synthesis, toxic solvents or harmful post-selenization.
Molybdenum carbide nanoparticles within carbon nanotubes as superior catalysts for γ-valerolactone production via levulinic acid hydrogenation
Authors: Mai Estevão F. , Machado Marta A. , Davies Thomas E. , Lopez-Sanchez Jose A. , Teixeira da Silva Victor
Published: July 2014

We report here for the first time that supported molybdenum carbide is an efficient catalyst to selectively convert levulinic acid into γ-valerolactone in the aqueous phase.
Synthesis and study of (R)- and (S)-β-hydroxyphosphonate acyclonucleosides as structural analogues of (S)-HPMPC (cidofovir)
Authors: Kasthuri Mahesh , El Amri Chahrazade , Lefort Valérie , Périgaud Christian , Peyrottes Suzanne
Published: July 2014

Modification of the acyclic chain highly impacts antiviral activity and recognition by human nmpks.
An enzymatic approach to bifunctional chelating agents
Authors: Minazzi Paolo , Lattuada Luciano , Menegotto Ivan G. , Giovenzana Giovanni B.
Published: July 2014

Three novel BFCAs are obtained through an original protocol involving an enzymatic hydrolysis as the key step.
Folded alkyl chains in water-soluble capsules and cavitands
Authors: Gavette Jesse V. , Zhang Kang-Da , Ajami Dariush , Rebek Julius
Published: July 2014

A deep cavitand with ionic “feet” dimerizes around hydrophobic compounds in D2O.
Convergent chemoenzymatic synthesis of a library of glycosylated analogues of pramlintide: structure–activity relationships for amylin receptor agonism
Authors: Kowalczyk Renata , Brimble Margaret A. , Tomabechi Yusuke , Fairbanks Antony J. , Fletcher Madeleine , Hay Debbie L.
Published: July 2014

The synthesis of a library of N-glycosylated pramlintide analogues to establish the SAR of amylin receptor agonism has been undertaken.
Overcoming carbon deactivation in biogas reforming using a hydrothermally synthesised nickel perovskite catalyst
Authors: Evans S. E. , Good O. J. , Staniforth J. Z. , Ormerod R. M. , Darton R. J.
Published: July 2014

A hydrothermally synthesised nickel-doped perovskite catalyst is demonstrated to have excellent selectivity for biogas reforming without suffering from deactivation by carbon formation.
Synthesis of functionalized dispiro-oxindoles through azomethine ylide dimerization and mechanistic studies to explain the diastereoselectivity
Authors: Banerjee Prabal , Pandey Ashok Kumar
Published: July 2014

Synthesis of functionalized dispiro-oxindoles via [3 + 3]-cycloaddition of azomethine ylide generated from condensation of isatin and proline is reported. A transition state model for the origin of diastereoselectivity and mechanism of formation of these types of adducts is proposed.
Synthesis of carbon quantum dot-surface modified P25 nanocomposites for photocatalytic degradation of p-nitrophenol and acid violet 43
Authors: Zheng Fengying , Wang Zhenhua , Chen Jie , Li ShunXing
Published: July 2014

A new efficient and stable visible light driven photocatalyst, carbon quantum dots (CQDs)-surface modified P25 nanocomposite, was successfully prepared by chemical adsorption of CQDs onto the surface of TiO2 nanoparticles and then used for water treatment.
Azide trapping of metallocarbenes: generation of reactive C-acylimines and domino trapping with nucleophiles
Authors: Bott Tina M. , Atienza Bren Jordan , West F. G.
Published: July 2014

Diazocarbonyl compounds react with pendent azides under copper catalysis to generate reactive C-acylimines that can be trapped with carbon π-nucleophilesin situ.
Interface deformations affect the orientation transition of magnetic ellipsoidal particles adsorbed at fluid–fluid interfaces
Authors: Davies Gary B. , Krüger Timm , Coveney Peter V. , Harting Jens , Bresme Fernando
Published: July 2014

Magnetic ellipsoidal particles adsorbed at a fluid–fluid interface create dipolar interface deformations in response to a magnetic field, which affects their orientation and may lead to novel particle monolayer structures.
Reactive coaxial electrospinning of ZrP/ZrO2 nanofibres
Authors: Subianto S. , Donnadio A. , Cavaliere S. , Pica M. , Casciola M. , Jones D. J. , Rozière J.
Published: July 2014

Zirconium phosphate/zirconium oxide nanofibres have been fabricated using a novel, reactive coaxial electrospinning approach where a zirconium precursor and a phosphorus source are spun together from separate solutions using a coaxial needle.
Hybridization of brookite TiO2 with g-C3N4: a visible-light-driven photocatalyst for As3+ oxidation, MO degradation and water splitting for hydrogen evolution
Authors: Zang Yipeng , Li Liping , Xu Yangsen , Zuo Ying , Li Guangshe
Published: July 2014

A visible-light-driven photocatalyst of brookite TiO2 coupled with g-C3N4 exhibited high efficiency for As3+ oxidation, MO degradation, and hydrogen evolution.
Li- and Na-reduction products of meso-Co3O4form high-rate, stably cycling battery anode materials
Authors: Klavetter Kyle. C. , Garcia Stephany , Dahal Naween , Snider Jonathan L. , Pedro de Souza J. , Cell Trevor H. , Cassara Mark A. , Heller Adam , Humphrey Simon M. , Mullins C. Buddie
Published: July 2014

A meso-porous Co3O4has been found to retain its structure and cycle stably in a Li-ion or Na-ion battery.
A photoacoustic approach for monitoring the drug release of pH-sensitive poly(β-amino ester)s
Authors: Duan Zhongyu , Gao Yu-Juan , Qiao Zeng-Ying , Fan Gang , Liu Ya , Zhang Di , Wang Hao
Published: July 2014

In this work, we prepared PEG modified poly(β-amino ester) graft copolymers with pH-sensitive properties. Doxorubicin (DOX) and squaraine (SQ) dye as a photoacoustic tomography (PAT) reporter molecule were loaded into the hydrophobic core of polymeric micelles, and their release profiles investigated using the PAT technique.
CEE-active red/near-infrared fluorophores with triple-channel solid-state “ON/OFF” fluorescence switching
Authors: Cheng Xiao , Zhang Zhenyu , Zhang Houyu , Han Shenghua , Ye Kaiqi , Wang Lu , Zhang Hongyu , Wang Yue
Published: July 2014

Crystalline-enhanced red/NIR emission of beryllium complexes can be switched between dark and bright states by different stimuli, providing the first example of reversible multiple-channel solid-state fluorescence “ON/OFF” switching.
Bright and stable light-emitting electrochemical cells based on an intramolecularly π-stacked, 2-naphthyl-substituted iridium complex
Authors: Schneider Gabriel E. , Pertegás Antonio , Constable Edwin C. , Housecroft Catherine E. , Hostettler Nik , Morris Collin D. , Zampese Jennifer A. , Bolink Henk J. , Junquera-Hernández José M. , Ortí Enrique , Sessolo Michele
Published: July 2014

LECs incorporating [Ir(ppy)2(Naphbpy)][PF6] (Hppy = 2-phenylpyridine, Naphbpy = 6-(2-naphthyl)-2,2′-bipyridine) in the emissive layer show high luminance and exceptional stabilities.
Ion-induced cycle opening of a diarylethene and its application on visual detection of Cu2+ and Hg2+ and keypad lock
Authors: He Junjie , He Jingxian , Wang Tingting , Zeng Heping
Published: July 2014

Only the closed form of the diarylethene reported here can combine with the metal ions, meanwhile the coordination would surprisingly induce cycle opening of photochromic unit and color bleaching process. These properties can be applied in detection of Cu2+ and Hg2+ ions and single molecular keypad lock.
Reducing handover delays for seamless multimedia service in IEEE 802.11 networks
Authors: Lee Doohyun , Won Daehee , Piran Md. Jalil , Suh Doug Young
Published: July 2014

In IEEE 802.11 wireless local area network (WLAN) environments, handovers occur when a mobile node (client) moves from the coverage area of one access point (AP) to that of another AP. In particular, a handover in multimedia streaming settings requires a series of tasks to be executed – recognising the disconnection to the currently associated AP, searching for other APs in client visibility and so on. The time taken to perform these tasks gives rise to an interruption of service for about 6 s, which greatly decreases users’ quality of experience (QoE). To reduce service disruptions caused by handovers in IEEE 802.11 networks, a soft proactive handover scheme that exploits the received signal strength indicator (RSSI) and scalable video coding (SVC) is proposed. The proposed scheme predicts the time that a handover process is going to start using the RSSI values and receives the lightweight base layer code of the SVC‐encoded video during a certain interval before the predicted handover starts. Experimental results show that the proposed scheme can minimise service interruption times during the 802.11 handover operations, thereby increasing QoE.
Ultra‐wideband unequal in‐phase power divider using three‐line coupled structure
Authors: Zhu H. , Abbosh A. , Guo L.
Published: July 2014

A compact ultra‐wideband in‐phase power divider using a three‐line coupled structure is proposed. The power division of the device depends on the coupling factors between the centreline and the two sidelines. For an enhanced isolation between the output ports, a 100 Ω chip resistor is connected between the ends of the two sidelines, whereas the end of the centre line is grounded. To verify the design, a prototype with 2:1 power division was fabricated and tested. The measured results validate the ultra‐wideband performance with more than 12 dB return loss, more than 13 dB isolation and <0.2 dB and 4° amplitude and phase imbalances, respectively, across the band 3.1–10.6 GHz.
Wideband unidirectional circularly polarised slot array with integrated feeding network
Authors: Jiang Xiaolei , Zhang Zhijun , Li Yue , Feng Zhenghe
Published: July 2014

A wideband planar unidirectional circularly polarised slot array is proposed. The slot array has a truly planar structure where the feeding network is integrated with the radiating elements on the same substrate, which makes it low cost and easy to fabricate. The measured result shows that the proposed array obtains an impedance bandwidth of 33.8% and an axial ratio bandwidth of 24.5%. The proposed array has a good unidirectional pattern and can be used in base station applications.
Joint detection scheme for spectrum sensing over time‐variant flat fading channels
Authors: Sun Mengwei , Li Bin , Song Qizhu , Zhao Long , Zhao Chenglin
Published: July 2014

As the application scope of cognitive radio grows continuously, time‐variant flat fading (TVFF) channels become common in practical spectrum sensing scenarios. Unfortunately, most existing spectrum sensing methods which are designed for time‐invariant propagation channels could hardly obtain good performance when they operate in realistic TVFF channels. To combat this difficulty, in this investigation the authors design a promising spectrum sensing method. Firstly, a novel dynamic state‐space model is proposed in which a two‐state Markov chain is employed to abstract the evolution of primary user states and a finite‐state Markov channel model is utilised to characterise the TVFF channel. Secondly, based on the maximum a posteriori probability criteria and the particle filtering mechanic, a joint estimation algorithm of the time‐dependent fading channel gain and the state of primary user is presented. Experimental simulations verify the performance superiority of the authors presented joint detection scheme, which could be properly applied to spectrum sensing in realistic TVFF channels.
Voltage look‐up table method to control multilevel cascaded transformerless inverters with unequal DC rail voltages
Authors: Ebadi Mazdak , Joorabian Mahmood , Moghani Javad Shokrollahi
Published: July 2014

This study presents a new voltage control algorithm for multilevel inverters which are used to connect the distributed generation (DG) sources (like photovoltaic cells) to the network, which is called the voltage look‐up table method (VLUTM). This method can build up an almost sinusoidal voltage at the inverter output with the least number of switching in the power circuit, and the best possible harmonic spectrum without the need to any big filtering. On the other hand, in some specific applications where the DG has been set up beside a non‐linear load, VLUTM can make a reference voltage based on the reference current to take a desired current form the DG. This way the DG can compensate the major low‐order load current harmonics and improve the source side current THD greatly. Decreasing the switching frequency as much as possible, which leads to better efficiency and less EMI problems, the capability of implementation both in single phase and three phase circuitry, and the very simple and desired current control, would be the major benefits of this method. The simulation results taken from Matlab/Simulink and the experimental results on a 1 kVA experimental prototype are presented to evaluate the performance of this method.
Simple control method for three‐phase pulse‐width modulation rectifier of switching power supply under unbalanced and distorted supply voltages
Authors: Luo An , Jin Guobin , Xiao Huagen , Xiong Qiaopo , Wang Yichao , Xie Ning
Published: July 2014

This study presents an improved dead‐beat control method for three‐phase pulse‐width modulation rectifier of the switching power supply under source‐voltage harmonics and unbalance disturbances. First, a reference currents extraction method and an active negative sequence currents injection method for the dead‐beat control are presented to suppress the input harmonic currents and the second harmonic voltage of the DC‐link voltage in the rectifier. Then, active disturbance rejection control is presented to substitute for the PI control, which can improve the transient response and strengthen the antidisturbance ability of the rectifier. Finally, to improve the efficiency of the power supply, two auxiliary inductors are introduced to realise soft switching of the DC/DC converter, which is an idea of taking the rectifier and the DC/DC converter as a whole. The feasibility and superior performances of the presented control methods and topology have been validated by the experimental results.
Improved control strategy with grid‐voltage feedforward for LCL‐filter‐based inverter connected to weak grid
Authors: Xu Jinming , Xie Shaojun , Tang Ting
Published: July 2014

In grid‐connected LCL‐filtered inverters, the dual‐loop current control is widely used. The LCL resonance is highly damped by proper feedback of the capacitor current. To suppress low‐frequency current harmonics, a grid‐voltage feedforward is commonly used. However, the system performance with such control is declined when connecting to a weak grid. Phase and gain margins are largely reduced while the proportional feedforward is used. The margins get worse and instability is aroused if the derivative feedforward is further implemented. Besides, a negative impact on the rejection of grid‐voltage‐induced harmonics is produced. To improve the control performance in the weak grid case, an adaptive control has been proposed. Adopting the estimated grid impedance, the signal for the grid‐voltage feedforward is modified and the controller is adjusted with an adaptive rule to maintain a good phase margin or a high bandwidth. Performances of the inverter with the typical and the proposed methods are compared. Simulation and experimental results have demonstrated that the grid‐connected LCL‐filtered inverter with the proposed method produced a high‐quality current while large grid impedance existed.
Controlling current and voltage type interfaces in power‐hardware‐in‐the‐loop simulations
Authors: Dargahi Mahdi , Ghosh Arindam , Davari Pooya , Ledwich Gerard
Published: July 2014

The usual practice to study a large power system is through digital computer simulation. However, the impact of large scale use of small distributed generators on a power network cannot be evaluated strictly by simulation since many of these components cannot be accurately modelled. Moreover, the network complexity makes the task of practical testing on a physical network nearly impossible. This study discusses the paradigm of interfacing a real‐time simulation of a power system to real‐life hardware devices. This type of splitting a network into two parts and running a real‐time simulation with a physical system in parallel is usually termed as power‐hardware‐in‐the‐loop (PHIL) simulation. The hardware part is driven by a voltage source converter that amplifies the signals of the simulator. In this paper, the effects of suitable control strategy on the performance of PHIL and the associated stability aspects are analysed in detail. The analyses are validated through several experimental tests using an real‐time digital simulator.
Softening in silver-nanowire-filled polydimethylsiloxane nanocomposites
Authors: Seshadri Indira , Esquenazi Gibran L. , Borca-Tasciuc Theo , Keblinski Pawel , Ramanath Ganpati
Published: July 2014

We report that silver nanowire fillers can result in a three-fold decrease in viscoelastic storage modulus of polydimethylsiloxane composites above a low critical filler fraction of ∼0.5%, contrary to theoretical predictions presaging a modulus increase. Similar fractions of silver nanocube fillers result in no such observable effects. Rheology measurements and calorimetric kinetics analyses reveal that high surface area nanowire filler percolation curtails macromolecular mobility via pre-cure gelation, and hinders crosslinking. Our findings on the effect of metal filler aspect ratio on polymer stiffness at low loading fractions would be important for designing nanocomposites for applications.
The effect of substrate on thermodynamic and kinetic anisotropies in atomic thin films
Authors: Haji-Akbari Amir , Debenedetti Pablo G.
Published: July 2014

Glasses have a wide range of technological applications. The recent discovery of ultrastable glasses that are obtained by depositing the vapor of a glass-forming liquid onto the surface of a cold substrate has sparked renewed interest in the effects of confinements on physicochemical properties of liquids and glasses. Here, we use molecular dynamics simulations to study the effect of substrate on thin films of a model glass-forming liquid, the Kob-Andersen binary Lennard-Jones system, and compute profiles of several thermodynamic and kinetic properties across the film. We observe that the substrate can induce large oscillations in profiles of thermodynamic properties such as density, composition, and stress, and we establish a correlation between the oscillations in total density and the oscillations in normal stress. We also demonstrate that the kinetic properties of an atomic film can be readily tuned by changing the strength of interactions between the substrate and the liquid. Most notably, we show that a weakly attractive substrate can induce the emergence of a highly mobile region in its vicinity. In this highly mobile region, structural relaxation is several times faster than in the bulk, and the exploration of the potential energy landscape is also more efficient. In the subsurface region near a strongly attractive substrate, however, the dynamics is decelerated and the sampling of the potential energy landscape becomes less efficient than the bulk. We explain these two distinct behaviors by establishing a correlation between the oscillations in kinetic properties and the oscillations in lateral stress. Our findings offer interesting opportunities for designing better substrates for the vapor deposition process or developing alternative procedures for situations where vapor deposition is not feasible.
A new broadband homonuclear mixing pulse for NMR with low applied power
Authors: Coote Paul , Leigh Kendra E. , Yu Tsyr-Yan , Khaneja Navin , Wagner Gerhard , Arthanari Haribabu
Published: July 2014

Broadband homonuclear mixing pulses with low radiofrequency power are essential for NMR spectroscopy of proteins and small molecules, especially for emerging applications in high field NMR. We have analytically designed a mixing pulse with high bandwidth-to-power ratio, using our recently developed multi-frame method. Here, we compare the new pulse, NF4 (mixing in the fourth nutating frame), to the best currently available sequence, focusing on the low-power regime. We use simulations and experiments to compare the two pulses’ relaxation properties and bandwidth, and demonstrate that NF4 has approximately 1.35 times higher bandwidth, with similar effective relaxation. Therefore, NF4 is a good choice for broadband homonuclear mixing, particularly when the available radiofrequency power is limited.
Pressure-driven variations of hydrogen bonding energy in ammonium azide (NH4N3): IR absorption and Raman scattering studies
Authors: Wu Xiaoxin , Ma Fengxian , Ma Chunli , Cui Hang , Liu Zhenxian , Zhu Hongyang , Wang Xiaoli , Cui Qiliang
Published: July 2014

In this study, high pressure infrared (IR) absorption and Raman scattering studies for ammonium azide (NH4N3) were carried out at room temperature up to 20 GPa and 22 GPa, respectively. For comparison and further assignment, the vibrational spectra at ambient conditions were calculated using CASTEP code, particularly for the far- and mid-IR modes. The recorded vibrational data consistently indicated a pressure-induced phase transition at 2.9 GPa. All observed vibrational modes maintained their identities at the high pressure phase, indicating that NH4N3 was still presented in the form of ammonium cations and azide anions linked by the hydrogen bond (N–H⋯N). Above 2.9 GPa, the relative magnitude of the torsional mode weakened and the N−H symmetric stretch displayed a redshift, indicating strengthened hydrogen bonding energy. The opposite effects were observed above 12 GPa, where the relative magnitude of the torsional mode strengthened and the N−H symmetric stretch reverted to a blueshift, indicating weakened hydrogen bonding energy. It can be concluded that the hydrogen bonding energy exhibited a weakening (0–2.9 GPa), strengthening (2.9–12 GPa), and then again weakening (12–22 GPa) phenomena with the increasing of compression. The hydrogen bonding energy changing with the increase of pressure can be ascribed to a phase transition at 2.9 GPa and a rotational or bending behavior of azide ions at 12 GPa.
Flexible microwave absorbers based on barium hexaferrite, carbon black, and nitrile rubber for 2–12 GHz applications
Authors: Vinayasree S. , Soloman M. A. , Sunny Vijutha , Mohanan P. , Kurian Philip , Joy P. A. , Anantharaman M. R.
Published: July 2014

Flexile single layer electromagnetic wave absorbers were designed by incorporating appropriate amounts of carbon black in a nitrile butadiene rubber matrix along with an optimized amount of magnetic counterpart, namely, barium hexaferrite for applications in S, C, and X-bands. Effective dielectric permittivity and magnetic permeability were measured using cavity perturbation method in the frequency range of 2–12 GHz. The microwave absorbing characteristics of the composites were studied in the S, C, and X-bands employing a model in which an electromagnetic wave is incident normally on a metal terminated single layer. Reflection loss exceeding −20 dB is obtained for all the samples in a wide frequency range of 2–12 GHz when an appropriate absorber thickness between 5 and 9 mm is chosen. The impact of carbon black is clearly observed in the optimized composites on the mechanical strength, thickness, band width of absorption, dielectric properties, and absorptivity.
Demonstration of x-ray fluorescence imaging of a high-energy-density plasma
Authors: MacDonald M. J. , Keiter P. A. , Montgomery D. S. , Biener M. M. , Fein J. R. , Fournier K. B. , Gamboa E. J. , Klein S. R. , Kuranz C. C. , LeFevre H. J. , Manuel M. J.-E. , Streit J. , Wan W. C. , Drake R. P.
Published: July 2014

Experiments at the Trident Laser Facility have successfully demonstrated the use of x-ray fluorescence imaging (XRFI) to diagnose shocked carbonized resorcinol formaldehyde (CRF) foams doped with Ti. One laser beam created a shock wave in the doped foam. A second laser beam produced a flux of vanadium He-α x-rays, which in turn induced Ti K-shell fluorescence within the foam. Spectrally resolved 1D imaging of the x-ray fluorescence provided shock location and compression measurements. Additionally, experiments using a collimator demonstrated that one can probe specific regions within a target. These results show that XRFI is a capable alternative to path-integrated measurements for diagnosing hydrodynamic experiments at high energy density.
Structural, vibrational, and elastic properties of a calcium aluminosilicate glass from molecular dynamics simulations: The role of the potential
Authors: Bauchy M.
Published: July 2014

We study a calcium aluminosilicate glass of composition (SiO2)0.60(Al2O3)0.10(CaO)0.30 by means of molecular dynamics. To this end, we conduct parallel simulations, following a consistent methodology, but using three different potentials. Structural and elastic properties are analyzed and compared to available experimental data. This allows assessing the respective abilities of the potentials to produce a realistic glass. We report that, although all these potentials offer a reasonable glass structure, featuring tricluster oxygen atoms, their respective vibrational and elastic predictions differ. This allows us to draw some general conclusions about the crucial role, or otherwise, of the interaction potential in silicate systems.
A high-throughput cellulase screening system based on droplet microfluidics
Authors: Ostafe Raluca , Prodanovic Radivoje , Lloyd Ung W. , Weitz David A. , Fischer Rainer
Published: July 2014

A new ultra-high-throughput screening assay for the detection of cellulase activity was developed based on microfluidic sorting. Cellulase activity is detected using a series of coupled enzymes leading to the formation of a fluorescent product that can be detected on a chip. Using this method, we have achieved up to 300-fold enrichments of the active population of cells and greater than 90% purity after just one sorting round. In addition, we proved that we can sort the cellulase-expressing cells from mixtures containing less than 1% active cells.
The interaction of organic adsorbate vibrations with substrate lattice waves in methyl-Si(111)-(1 × 1)
Authors: Brown Ryan D. , Hund Zachary M. , Campi Davide , O’Leary Leslie E. , Lewis Nathan S. , Bernasconi M. , Benedek G. , Sibener S. J.
Published: July 2014

A combined helium atom scattering and density functional perturbation theory study has been performed to elucidate the surface phonon dispersion relations for both the CH3-Si(111)-(1 × 1) and CD3-Si(111)-(1 × 1) surfaces. The combination of experimental and theoretical methods has allowed characterization of the interactions between the low energy vibrations of the adsorbate and the lattice waves of the underlying substrate, as well as characterization of the interactions between neighboring methyl groups, across the entire wavevector resolved vibrational energy spectrum of each system. The Rayleigh wave was found to hybridize with the surface rocking libration near the surface Brillouin zone edge at both the ${\rm \bar M}$M¯-point and ${\rm \bar K}$K¯-point. The calculations indicated that the range of possible energies for the potential barrier to the methyl rotation about the Si-C axis is sufficient to prevent the free rotation of the methyl groups at a room temperature interface. The density functional perturbation theory calculations revealed several other surface phonons that experienced mode-splitting arising from the mutual interaction of adjacent methyl groups. The theory identified a Lucas pair that exists just below the silicon optical bands. For both the CH3- and CD3-terminated Si(111) surfaces, the deformations of the methyl groups were examined and compared to previous experimental and theoretical work on the nature of the surface vibrations. The calculations indicated a splitting of the asymmetric deformation of the methyl group near the zone edges due to steric interactions of adjacent methyl groups. The observed shifts in vibrational energies of the -CD3 groups were consistent with the expected effect of isotopic substitution in this system.
Electric driven instability in a charged drop immersed in a viscous dielectric fluid
Authors: Miloh Touvia
Published: July 2014

Linear stability analysis is performed on an electrically charged spherical viscous liquid drop with a spherical rigid core surrounded by a second Newtonian uncharged fluid of different dielectric properties. Dispersion relation and growth rate of the most unstable interfacial mode is found by taking into account, viscous, electrostatic, gravity, and surface tension effects. Several physical interesting cases, such as drop oscillations in vacuum or those involving planar 2D interfaces, are obtained as limiting cases. Numerical simulations are performed for various geometrics, flow, and electric parameters in order to determine the threshold value of the applied voltage or electric charge which lead to multi-jetting phenomena on the interface. The characteristic wave-length (spacing) and size of these radial protrusions is determined in terms of the electric forcing which is an important design parameter for the controlled needleless electrospinning phenomena.
A straightforward method for Vacuum-Ultraviolet flux measurements: The case of the hydrogen discharge lamp and implications for solid-phase actinometry
Authors: Fulvio D. , Brieva A. C. , Cuylle S. H. , Linnartz H. , Jäger C. , Henning T.
Published: July 2014

Vacuum-Ultraviolet (VUV) radiation is responsible for the photo-processing of simple and complex molecules in several terrestrial and extraterrestrial environments. In the laboratory such radiation is commonly simulated by inexpensive and easy-to-use microwave-powered hydrogen discharge lamps. However, VUV flux measurements are not trivial and the methods/devices typically used for this purpose, mainly actinometry and calibrated VUV silicon photodiodes, are not very accurate or expensive and lack of general suitability to experimental setups. Here, we present a straightforward method for measuring the VUV photon flux based on the photoelectric effect and using a gold photodetector. This method is easily applicable to most experimental setups, bypasses the major problems of the other methods, and provides reliable flux measurements. As a case study, the method is applied to a microwave-powered hydrogen discharge lamp. In addition, the comparison of these flux measurements to those obtained by O2 actinometry experiments allow us to estimate the quantum yield (QY) values QY122 = 0.44 ± 0.16 and QY160 = 0.87 ± 0.30 for solid-phase O2 actinometry.
Multilayer magnetic waveguides: Optimizing nonreciprocal propagation in the 50–70 GHz range
Authors: Anderson N. R. , Camley R. E.
Published: July 2014

Waves in magnetic systems often show nonreciprocal propagation, where the properties of a wave depends on whether it is travelling in a forward or reversed direction. This fundamental property is used in devices such as isolators, which often use a transverse electric (TE) polarized wave. In this paper, we study propagation of electromagnetic waves in small microstrip waveguides where the wave propagates at an arbitrary angle with respect to the magnetization direction. The angle allows mixtures of TE and transverse magnetic (TM) modes. This has distinct benefits, allowing the nonreciprocity typically found in TE modes, but also allowing propagation of low frequency TM modes, which do not have a cut-off frequency. Our calculations, using Barium hexaferrite as the magnetic material, show significant nonreciprocity and isolation are possible. Differences in attenuation above 75 dB/cm are found for these mixed-polarization waves for propagation angles of about 40°. We study nonreciprocal propagation as a function of propagation angle and other material parameters for both primarily TM and primarily TE modes.