bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of vitamin C and vitamin E supplementation on endothelial function: a systematic review and meta-analysis of randomised controlled trials
Authors: Ashor Ammar W. , Siervo Mario , Lara Jose , Oggioni Clio , Afshar Sorena , Mathers John C.
Published: April 2015

Randomised controlled trials (RCT) testing the effects of antioxidant supplements on endothelial function (EF) have reported conflicting results. We aimed to investigate the effects of supplementation with antioxidant vitamins C and E on EF and to explore factors that may provide explanations for the inconsistent results. We searched four databases (MEDLINE, Embase, Cochrane Library and Scopus) from inception until May 2014 for RCT involving adult participants aged ≥ 18 years who were supplemented with vitamins C and E alone or in combination for more than 2 weeks and reporting changes in EF measured using flow mediated dilation or forearm blood flow. Data were pooled as standardised mean difference (SMD) and analysed using a random-effects model. Significant improvements in EF were observed in trials supplementing with vitamin C alone (500–2000 mg/d) (SMD: 0·25, 95 % CI 0·02, 0·49,P= 0·043) and vitamin E alone (300–1800 IU/d; 1 IU vitamin E = 0·67 mg natural vitamin E) (SMD: 0·48, 95 % CI 0·23, 0·72,P= 0·0001), whereas co-administration of both vitamins was ineffective (vitamin C: 500–2000 mg/d; vitamin E: 400–1200 IU/d) (SMD: 0·12, 95 % CI − 0·18, 0·42,P= 0·428). The effect of vitamin C supplementation on EF increased significantly with age (β 0·023, 95 % CI 0·001, 0·05,P= 0·042). There was a significant negative correlation between baseline plasma vitamin E concentration and the effect of vitamin E supplementation on EF (β − 0·03, 95 % CI − 0·06, − 0·001,P= 0·029). Supplementation with either vitamin C or vitamin E alone improves EF. However, subgroup analysis emphasises the importance of careful characterisation and selection of a population group which may benefit from such supplementation.
The Missing ‘Allen–Persons’ Cases of Conscience
Authors: Holmes Peter
Published: April 2015

Cardinal William Allen, Robert Persons, S. J. and the Rev. Gregory Martin supervised the production in about 1581 of a discussion of cases of consciences, which were intended for the use by students trained for the English mission at the Venerable English College, Rome. The principal manuscript copy of these cases previously known is missing a final section. This has now turned up in the Library of the Society of Antiquaries of London. This article consists of an introduction to the manuscript sources, the cases and their doctrine; a transcript of the Latin text; and a translation of it into English.
ICJ Halts Antarctic Whaling – Japan Starts Again
Authors: Payne Cymie R.
Published: April 2015

The International Court of Justice (ICJ) judgment inWhaling in the Antarctic, a dispute brought by Australia against Japan, found that Japan had violated the International Convention for the Regulation of Whaling (ICRW) moratoria on all commercial whaling and the use of factory ships to process whales, and also the prohibition on whaling in the Southern Ocean Sanctuary. In the course of analyzing whether special permits issued by Japan qualified for the scientific whaling exemption under Article VIII ICRW, the Court benefited from a more robust scientific fact-finding process than at times in the past. The judgment emphasized the mutual obligations of this multilateral agreement by taking the view that the provisions of the ICRW’s scientific whaling exemptions are neither self-judging nor subject to a ‘margin of appreciation’ in favour of a state party claiming the exemption. The case was driven by conflicting attitudes towards commercial whaling, and also towards global common spaces. The ICJ’s decision and Japan’s response indicate the limits of the ICRW in resolving those differences.
Growth phase-specific evolutionary benefits of natural transformation in Acinetobacter baylyi
Authors: Utnes Ane L G , Sørum Vidar , Hülter Nils , Primicerio Raul , Hegstad Joachim , Kloos Julia , Nielsen Kaare M , Johnsen Pål J
Published: April 2015

Natural transformation in bacteria facilitates the uptake and genomic integration of exogenous DNA. This allows horizontal exchange of adaptive traits not easily achieved by point mutations, and has a major role in the acquisition of adaptive traits exemplified by antibiotic resistance determinants and vaccination escape. Mechanisms of DNA uptake and genomic integration are well described for several naturally transformable bacterial species; however, the selective forces responsible for its evolution and maintenance are still controversial. In this study we evolved transformation-proficient and -deficient Acinetobacter baylyi for 175 days in serial transfer cultures where stress was included. We found that natural transformation-proficient populations adapted better to active growth and early stationary phase. This advantage was offset by the reduced performance in the late stationary/death phase. We demonstrate fitness trade-offs between adaptation to active growth and survival in stationary/death phase caused by antagonistic pleiotropy. The presented data suggest that the widely held assumption that recombination speeds up adaptation by rapid accumulation of multiple adaptive mutations in the same genetic background is not sufficient to fully account for the maintenance of natural transformation in bacteria.
The diversity and host interactions of Propionibacterium acnes bacteriophages on human skin
Authors: Liu Jared , Yan Riceley , Zhong Qiao , Ngo Sam , Bangayan Nathanael J , Nguyen Lin , Lui Timothy , Liu Minghsun , Erfe Marie C , Craft Noah , Tomida Shuta , Li Huiying
Published: April 2015

The viral population, including bacteriophages, is an important component of the human microbiota, yet is poorly understood. We aim to determine whether bacteriophages modulate the composition of the bacterial populations, thus potentially playing a role in health or disease. We investigated the diversity and host interactions of the bacteriophages of Propionibacterium acnes, a major human skin commensal implicated in acne pathogenesis. By sequencing 48 P. acnes phages isolated from acne patients and healthy individuals and by analyzing the P. acnes phage populations in healthy skin metagenomes, we revealed that P. acnes phage populations in the skin microbial community are often dominated by one strain. We also found phage strains shared among both related and unrelated individuals, suggesting that a pool of common phages exists in the human population and that transmission of phages may occur between individuals. To better understand the bacterium–phage interactions in the skin microbiota, we determined the outcomes of 74 genetically defined Propionibacterium strains challenged by 15 sequenced phages. Depending on the Propionibacterium lineage, phage infection can result in lysis, pseudolysogeny, or resistance. In type II P. acnes strains, we found that encoding matching clustered regularly interspaced short palindromic repeat spacers is insufficient to confer phage resistance. Overall, our findings suggest that the prey–predator relationship between bacteria and phages may have a role in modulating the composition of the microbiota. Our study also suggests that the microbiome structure of an individual may be an important factor in the design of phage-based therapy.
Myricetin derived from Hovenia dulcis Thunb. ameliorates vascular endothelial dysfunction and liver injury in high choline-fed mice
Authors: Guo Jianjun , Meng Yonghong , Zhao Yan , Hu Yuanyuan , Ren Daoyuan , Yang Xingbin
Published: April 2015

The present study was conducted to explore the protective effects of myricetin (MYR) purified fromHovenia dulcisThunb. against vascular endothelial dysfunction and liver injury in mice fed with 3% dietary choline water.
The α-chymotrypsin-catalyzed Povarov reaction: one-pot synthesis of tetrahydroquinoline derivatives
Authors: Li Ling-Po , Cai Xin , Xiang Yang , Zhang Yong , Song Jian , Yang Da-Cheng , Guan Zhi , He Yan-Hong
Published: April 2015

The α-chymotrypsin from bovine pancreas (BPC) catalyzed three-component one-pot Povarov reaction for the synthesis of tetrahydroquinoline derivatives is reported.
Experimental investigation of performance and emissions characteristics of waste cooking oil biodiesel and n-butanol blends in a compression ignition engine
Authors: Jindal M. , Rosha P. , Mahla S. K. , Dhir A.
Published: April 2015

Experimental investigations were conducted to evaluate the effects of n-butanol in biodiesel–diesel blends on the performance and emissions characteristics of a constant speed, direct injection diesel engine.
New insights into fluorinated TiO2(brookite, anatase and rutile) nanoparticles as efficient photocatalytic redox catalysts
Authors: Wang Yafang , Li Liping , Huang Xinsong , Li Qi , Li Guangshe
Published: April 2015

In this paper, we develop a fluorination methodology and optimize various synthesis conditions. We also demonstrate that photocatalytic redox activity is affected by the synergistic effect between surface fluorination and phase structure.
Cytotoxicity of guanine-based degradation products contributes to the antiproliferative activity of guanine-rich oligonucleotides
Authors: Zhang Nan , Bing Tao , Liu Xiangjun , Qi Cui , Shen Luyao , Wang Linlin , Shangguan Dihua
Published: April 2015

Guanine-rich oligonucleotides with lower nuclease resistance exhibited higher antiproliferative activity; guanine-based compounds showed highly concentration-dependent cytotoxicity.
An integrated closed-tube 2-plex PCR amplification and hybridization assay with switchable lanthanide luminescence based spatial detection
Authors: Lahdenperä Susanne , Spangar Anni , Lempainen Anna-Maija , Joki Laura , Soukka Tero
Published: April 2015

A proof-of-principle of a genuine closed-tube nucleic acid assay with integrated 2-plex PCR amplification and array-based detection has been presented.
Antimicrobial peptide LL-37 on surfaces presenting carboxylate anions
Authors: Qin G. T. , Lopez A. , Santos C. , McDermott A. M. , Cai C. Z.
Published: April 2015

Non-covalently immobilized antimicrobial peptide LL-37 attracts and rapidly kills bacteria upon contact.
Functional membranes via nanoparticle self-assembly
Authors: Green Erica , Fullwood Emily , Selden Julieann , Zharov Ilya
Published: April 2015

Nanoporous and ion conductive materials can be prepared by the self-assembly of nanoparticles, providing membranes with size and charge selectivity suitable for separation and possessing proton or lithium transport properties suitable for fuel cells and batteries.
Exploiting anthracene photodimerization within peptides: light induced sequence-selective DNA binding
Authors: Bullen Gemma A. , Tucker James H. R. , Peacock Anna F. A.
Published: April 2015

Here we detail the first example of anthracene photodimerisation in peptides, and use it to trigger a selective biomolecular recognition event.
Novel olfactory ligands via terpene synthases
Authors: Touchet Sabrina , Chamberlain Keith , Woodcock Christine M. , Miller David J. , Birkett Michael A. , Pickett John A. , Allemann Rudolf K.
Published: April 2015

A synthetic biology approach to the rational design of novel olfactory ligands is described.
Bismuth–lithium bonding in the ion pairs: LiBiL2, where L = a porphyrin or a salen ligand
Authors: Balasanthiran Vagulejan , Chisholm Malcolm H. , Durr Christopher B.
Published: April 2015

From the reaction between BiCl3 (1 equiv.) and LiN(SiMe3)2 (4 equiv.) and LH2 (2 equiv.), where L = a tetraphenylporphyrin, TPP, an octaethylporphyrin, OEP and phsalen in THF the title compounds have been obtained I LiBiTPP2, II LiBiOEP2, and IIIA LiBi(phsalen)2 and IIIB LiBi(phsalen)2·THF.
Group 4 metal compounds incorporating the amide ligand, [N(SiMe2{C6H4-2-OMe})2]−
Authors: Evans Lloyd T. J. , Farnaby Joy H. , Coles Martyn P. , Cloke F. Geoffrey N. , Hitchcock Peter B.
Published: April 2015

A bis(2-methoxybenzene)-substituted disilazide pincer ligand coordinates to group 4 metal compounds to afford a conformationally flexible metallacycle.
Catalytic catechol oxidation by copper complexes: development of a structure–activity relationship
Authors: Ording-Wenker Erica C. M. , Siegler Maxime A. , Lutz Martin , Bouwman Elisabeth
Published: April 2015

High activity for the catalytic oxidation of 3,5-di-tert-butylcatechol was achieved with complexes of ligands that stabilize the biomimetic CuII μ-thiolate complex, hinting at a similarity with the required Cu-oxo intermediates.
Ursolic acid inhibits the development of nonalcoholic fatty liver disease by attenuating endoplasmic reticulum stress
Authors: Li Jian-Shuang , Wang Wen-Jun , Sun Yu , Zhang Yu-Hao , Zheng Ling
Published: April 2015

Ursolic acid treatment inhibits steatosis by reducing hepatic ER stress.
Direct amidation of carboxylic acids with amines under microwave irradiation using silica gel as a solid support
Authors: Ojeda-Porras Andrea , Hernández-Santana Alejandra , Gamba-Sánchez Diego
Published: April 2015

A highly improved methodology for the direct amidation of carboxylic acids with amines using silica gel as a solid support and catalyst is described. Several examples using aliphatic, aromatic, unsaturated and fatty acids combined with primary and secondary amines are shown.
Supported gold nanoparticles as efficient and reusable heterogeneous catalyst for cycloisomerization reactions
Authors: Schröder Felix , Ojeda Manuel , Erdmann Nico , Jacobs Jeroen , Luque Rafael , Noël Timothy , Van Meervelt Luc , Van der Eycken Johan , Van der Eycken Erik V.
Published: April 2015

We have developed an attractive and green approach for the synthesis of spiroindolines under heterogeneous conditions using supported gold nanoparticles in combination with microwave irradiation.
Pd(ii)-catalyzed C(sp3)–H arylation of amino acid derivatives with click-triazoles as removable directing groups
Authors: Zhang Guofu , Xie Xiaoqiang , Zhu Jianfei , Li Shasha , Ding Chengrong , Ding Ping
Published: April 2015

An effective Pd(ii)-catalyzed C(sp3)–H arylation of amino acid derivatives using 1,2,3-triazoles as removable directing groups has been developed.
Aspartic acid based nucleoside phosphoramidate prodrugs as potent inhibitors of hepatitis C virus replication
Authors: Maiti Munmun , Maiti Mohitosh , Rozenski Jef , De Jonghe Steven , Herdewijn Piet
Published: April 2015

A series of novel nucleoside phosphoramidate protides has been synthesized and shown as potent inhibitors of hepatitis C virus replication. The conjugates are having a diverse structural variation in the promoiety part and can be catalytically processed to deliver active nucleotides.
Stereoselective reaction of 2-carboxythioesters-1,3-dithiane with nitroalkenes: an organocatalytic strategy for the asymmetric addition of a glyoxylate anion equivalent
Authors: Massolo Elisabetta , Benaglia Maurizio , Genoni Andrea , Annunziata Rita , Celentano Giuseppe , Gaggero Nicoletta
Published: April 2015

Under mild reaction conditions γ-nitro-β-aryl-α-keto esters with up to 92% ee were obtained, realizing a formal catalytic stereoselective conjugate addition of the glyoxylate anion synthon.
Gold(i)-catalyzed hydroindolylation of allenyl ethers
Authors: Kona Chandrababu Naidu , Shinde Mahesh H. , Ramana Chepuri V.
Published: April 2015

Nucleophilicity game: the gold(i)-catalyzed reaction/rearrangement of allenyl ethers has been investigated in the presence of indoles. The reaction outcome seems to be decided mainly by the nature of the pendant group of allenyl ether. Control experiments are indicative of an inner sphere mechanism for the hydroindolylation reaction.
Preparation of ultrahigh molecular weight ethylene/1-octene block copolymers using ethylene pressure pulse feeding policies
Authors: Liu Weifeng , Ojo Andrew Toye , Wang Wen-Jun , Fan Hong , Li Bo-Geng , Zhu Shiping
Published: April 2015

Ultrahigh molecular weight ethylene/1-octene block copolymers were prepared from ethylene pressure pulse feeding policies in living coordination polymerization.
Photodeposition of metal sulfides on titanium metal–organic frameworks for excellent visible-light-driven photocatalytic Cr(vi) reduction
Authors: Wang Hou , Yuan Xingzhong , Wu Yan , Chen Xiaohong , Leng Lijian , Zeng Guangming
Published: April 2015

A series of metal sulfides has been used to sensitize titanium metal–organic frameworks to form heterostructures through a facile photodeposition strategy.
Tunable picosecond spin dynamics in two dimensional ferromagnetic nanodot arrays with varying lattice symmetry
Authors: Saha Susmita , Barman Saswati , Sugimoto Satoshi , Otani YoshiChika , Barman Anjan
Published: April 2015

Tunable configurational anisotropy in spin-waves with up to 8-fold symmetry in closely packed nanodot lattices with rectangular, honeycomb and octagonal symmetry. The extrinsic nature of the anisotropy is due to angular variation of the magnetostatic field distribution.
Folded three-dimensional graphene with uniformly distributed mesopores for high-performance supercapacitors
Authors: Gao Tao , Xu Weijian , Gong Laijiang , Wang Zhao , Yang Zhongkui , Song Yawei , Xiong Yuanqin
Published: April 2015

Folded three-dimensional graphene (FTG) is prepared through self-assembly of graphite oxide (GO) and liquid-phase exfoliation graphene (LG), followed by sonication and reduction processes.
Delivery of dexamethasone from electrospun PCL–PEO binary fibers and their effects on inflammation regulation
Authors: Li Yan-Fang , Rubert Marina , Yu Ying , Besenbacher Flemming , Chen Menglin
Published: April 2015

Differences in surface topography, chemical composition, wettability and release kinetics of the anti-inflammatory drug dexamethasone among different PCL–PEO fibers collectively affected the regulation of inflammatory related gene expression.
Rapid and high-density covalent immobilization of Rhizomucor miehei lipase using a multi component reaction: application in biodiesel production
Authors: Mohammadi Mehdi , Ashjari Maryam , Dezvarei Shaghayegh , Yousefi Maryam , Babaki Mohadese , Mohammadi Javad
Published: April 2015

Rapid and high capacity immobilization ofRhizomucor mieheilipase on aldehyde-functionalized supports was performed under mild conditionviaa multi component reaction. The mechanism of immobilization reaction was determined as the Ugi reaction.
Base-promoted [1,4]-Wittig rearrangement of chalcone-derived allylic ethers leading to aromatic β-benzyl ketones
Authors: Gao Pei-Sen , Ye Fei , Dong Xiao-Yun , Chen Yun , Gao Zi-Wei , Zhang Wei-Qiang , Xu Li-Wen
Published: April 2015

Strong base promoted [1,4]-Wittig rearrangement of allylic ethers was developed in this work, in which the reaction provided a facile approach to the synthesis of aromatic β-benzyl ketones under controllable radical reaction conditions.
Tuning the mesomorphic properties of phenoxy-terminated smectic liquid crystals: the effect of fluoro substitution
Authors: Thompson Matthew , Carkner Carolyn , Mosey Nicholas J. , Kapernaum Nadia , Lemieux Robert P.
Published: April 2015

The mesomorphic properties of phenoxy-terminated liquid crystals can be tuned with fluoro substituents on the phenoxy end-group.
Chirality separation of mixed chiral microswimmers in a periodic channel
Authors: Ai Bao-quan , He Ya-feng , Zhong Wei-rong
Published: April 2015

We numerically studied the dynamics and separation of mixed chiral microswimmers in a channel with regular arrays of rigid half-circle obstacles. Mixed chiral microswimmers can be separated by applying the shear flow or the constant load.
Chiral spin crossover nanoparticles and gels with switchable circular dichroism
Authors: Gural'skiy Il'ya A. , Reshetnikov Viktor A. , Szebesczyk Agnieszka , Gumienna-Kontecka Elzbieta , Marynin Andriy I. , Shylin Sergii I. , Ksenofontov Vadim , Fritsky Igor O.
Published: April 2015

A chiral spin crossover complex was obtained in the form of nanoparticles and gels that undergo a cooperative spin state switch around room temperature.
Li2MnO3: a rare red-coloured manganese(iv) oxide exhibiting tunable red–yellow–green emission
Authors: Tamilarasan S. , Laha Sourav , Natarajan S. , Gopalakrishnan J.
Published: April 2015

Li2MnO3is a rare, red-coloured, Mn(iv) oxide that shows tunable red–yellow–green emission: both the red colour and the tunable emission likely arise from the honey-comb ordered LiMn6units in the rock salt based layered structure of this oxide.
Enhanced tunable color emission in transparent Ag/Mn2+codoped zinc borate glasses for broad band light source
Authors: Liu X. Y. , Guo H. , Ye S. , Peng M. Y. , Zhang Q. Y.
Published: April 2015

Enhanced ultra-broad band emission has been demonstrated in transparent Ag/Mn2+codoped zinc borate glasses for a broad band light source.
Tunable Schottky contacts in hybrid graphene–phosphorene nanocomposites
Authors: Hu Wei , Wang Tian , Yang Jinlong
Published: April 2015

Varying interfacial distance can control tunable Schottky contacts and barriers in hybrid graphene–phosphorene nanocomposites.
Estimation of glottal closure instants by considering speech signal as a spectrum
Authors: Sripriya N. , Nagarajan T.
Published: April 2015

Close to glottal closure instants (GCIs), the speech signal is expected to change its amplitude rapidly and, at GCIs, it is expected to have strong negative peaks. A novel algorithm that exploits these two properties for the estimation of GCIs is presented. Here, a symmetrised speech segment is assumed to be a Fourier transform (FT) of an even function. In such a case, at the locations of the GCIs, the strong negative peaks in the symmetrised speech segment correspond to zeros that lie considerably outside the unit circle in the z‐plane. The group delay spectrum of the time‐domain signal derived by taking inverse FT of this assumed FT is expected to take a value close to −2π at the angular locations of these zeros. Mapping frequency scale to time scale, the frequency bins for which group delay reaches −2π correspond to the locations of GCIs. Theoretical justification for the proposed approach is also presented by defining a novel function called the conditional group delay function. Systematic evaluation is carried out on the CMU Arctic database and the performance of the proposed technique is better than that of the algorithms namely DYPSA, ZFF, YAGA and is close to that of SEDREAMS.
Experimental Nakagami distributed noise model for molecular communication channels with no drift
Authors: Qiu Song , Wang Siyi , Guo Weisi
Published: April 2015

A molecular communication system operating in a pipe propagation channel with no induced flow is considered. Experimentally, it is shown that discrepancies in channel impulse response can be accurately modelled by an additive noise model. The noise amplitude is Nakagami distributed, and the shape and spread parameters of the distribution increase monotonically with propagation distance. Furthermore, demonstrated how the proposed noise model can be used to calculate the bit‐error‐rate and the capacity of a binary symmetric channel.
Wideband symmetric near‐field radiation pattern of sleeve dipole antenna by connecting additional ferrite‐loaded wire
Authors: Cho Jae‐Hyoung , Kim Se‐Yun
Published: April 2015

A scaled‐down laboratory experiment has been performed in a well‐controlled situation to find an enhanced rule for detecting a man‐made underground tunnel by employing a cross‐borehole frequency‐swept radar system. A sleeve dipole antenna, fed by a coaxial cable passing inside its upper arm, is employed to easily put and pull it along an air‐filled thin and long glass tube in scaled‐down experiments. The tube‐guided wave along the coaxial cable can be suppressed by ferrite‐loading along the coaxial cable. However, the dipole antenna fed by the ferrite‐loaded coaxial cable provides an asymmetrical radiation pattern in the near‐field region. To improve the symmetry of its near‐field radiation pattern, an additional ferrite‐loaded wire is connected to the lower arm of the sleeve dipole antenna. According to the scattering measurement by an air‐filled circular cylinder, the additional ferrite‐loaded wire improves the symmetry of the electric field by more 30 dB in the frequency range of 1.5–3 GHz.
Modified corner‐fed dual‐polarised stacked patch antenna for micro‐base station applications
Authors: Zhu Quanjiang , Yang Shiwen , Chen Zong
Published: April 2015

A modified corner‐fed dual‐polarised stacked patch antenna, with improved port isolation, is proposed. By shifting the feed points along the lower patch edge and introducing a triangular cut in the middle of another edge, the isolation between the two ports is improved significantly. The proposed antenna achieves a return loss of about 14 dB and a port isolation of more than 28 dB, within the band 2.5–2.7 GHz. The proposed antenna is highly suitable for micro‐base station applications in which features such as low profile, low cost and easy fabrication are required.
Broadband high‐power line driver with synthetic output impedance
Authors: Watkins G.T. , Mimis K.
Published: April 2015

Broadband line drivers usually include a back termination resistor at the output to match to the cable they are driving. Half the output power is dissipated in this resistor, therefore halving their efficiency. The resistive termination can be replaced with synthetic impedance using a combination of voltage and current feedback. This implementation is based around a current mirror amplifier capable of producing a 40 V peak‐to‐peak signal into a 50 Ω load impedance from a ±24 V supply. Using bandwidth enhancement, the small signal bandwidth was 15 MHz and the full power bandwidth was 6 MHz. When driving a 50 m long terminated 50 Ω coaxial cable, the amplifier produced a clean output signal with little ringing, indicating that it is well matched over a broad bandwidth.
Efficient vanishing point detection method in complex urban road environments
Authors: Ding Weili , Li Yong
Published: April 2015

Detecting the vanishing point in a road image is important for robot navigation, intelligent transportation and other fields. This study proposes a new vanishing point detection method that uses the vertical information in complex urban road and street environments. First, all straight lines in the road image are detected based on curvature scale space and principal component analysis methods. Second, a new road region extraction method is proposed to support vanishing point detection. In this method, the image is decomposed into approximate sky, vertical and road regions using the estimation envelopes of the vertical lines. Third, the straight lines in the road region are extracted using a path perspective triangle and line length limits. The straight lines are then categorised into groups using proposed grouping strategies. Finally, vanishing point candidates are calculated from paired lines extracted from different groups and from the same group, and the final vanishing point is then estimated for the urban road scene using the mean shift clustering method. The experimental results show that the proposed algorithm can estimate the vanishing point accurately and efficiently in complex urban road environments, despite interference from vehicles and pedestrians and on curved and unstructured roads.
Lightweight stator structure for a large diameter direct‐drive permanent magnet synchronous generator intended for wind turbines
Authors: Semken R. Scott , Nutakor Charles , Mikkola Aki , Alexandrova Yulia
Published: April 2015

A concept has been developed for a novel lightweight wheel structure intended for rotor and stator use in direct‐drive wind turbine generators. It uses a slanted spoke and rim architecture to provide maximum static structural performance with minimum weight. A unique attribute of the structure is its use of layered sheet steel elements to form the spokes and rim. Friction between layers establishes structural integrity. The interaction between layers and the resulting increase in damping normal to the stack offers improved dynamic performance. A static structural analysis of a full‐scale stator wheel structure for an 8 MW permanent magnet machine demonstrates the structural effectiveness of the architecture. To understand vibration characteristics of the lightweight wheel structure, a quarter‐scale prototype was built and an experimental modal analysis was carried out to measure actual radial vibration responses. This data was used to verify a numerical model, and there was good agreement between measured and predicted behaviours. Finally, a modal analysis was carried out for the full‐scale stator wheel structure. The dynamic performance of the wheel is acceptable for the stator of the 8 MW direct‐drive permanent magnet synchronous generator embodiment.
The effect of source Reynolds number on the rise height of a fountain
Authors: Burridge H. C. , Mistry A. , Hunt G. R.
Published: April 2015

The focus of this paper is to establish the effect of source Reynolds number, Re0, on the mean rise heights of Boussinesq miscible fountains and thereby the range of Re0 for which rise heights are independent of Re0. We present results from experiments on aqueous-saline fountains spanning source Reynolds numbers of 15 ≤ Re0 ≤ 4000 and source Froude numbers of 0.3 ≤ Fr0 ≤ 40. We provide threshold values for the source Reynolds number, i.e., values above which fountain rise height may be regarded as independent of Re0. For Reynolds numbers immediately beneath these threshold values, the fountain rise height increases as Re0 decreases—in agreement with Lin and Armfield [“The Reynolds and Prandtl number dependence of weak fountains,” Comput. Mech. 31, 379–389 (2003)]. At even lower Re0, we show that the rise heights reach a maximum and that further decreases in Re0 decrease the rise height attained—in agreement with Phillipe et al., [“Penetration of a negatively buoyant jet in a miscible liquid,” Phys. Fluids 17, 053601 (2005)]. As such, we resolve an apparent inconsistency within the existing fountain literature.
Computing with carbon nanotubes: Optimization of threshold logic gates using disordered nanotube/polymer composites
Authors: Massey M. K. , Kotsialos A. , Qaiser F. , Zeze D. A. , Pearson C. , Volpati D. , Bowen L. , Petty M. C.
Published: April 2015

This paper explores the use of single-walled carbon nanotube (SWCNT)/poly(butyl methacrylate) composites as a material for use in unconventional computing. The mechanical and electrical properties of the materials are investigated. The resulting data reveal a correlation between the SWCNT concentration/viscosity/conductivity and the computational capability of the composite. The viscosity increases significantly with the addition of SWCNTs to the polymer, mechanically reinforcing the host material and changing the electrical properties of the composite. The electrical conduction is found to depend strongly on the nanotube concentration; Poole-Frenkel conduction appears to dominate the conductivity at very low concentrations (0.11% by weight). The viscosity and conductivity both show a threshold point around 1% SWCNT concentration; this value is shown to be related to the computational performance of the material. A simple optimization of threshold logic gates shows that satisfactory computation is only achieved above a SWCNT concentration of 1%. In addition, there is some evidence that further above this threshold the computational efficiency begins to decrease.
Non-intrusive, high-resolution, real-time, two-dimensional imaging of multiphase materials using acoustic array sensors
Authors: Cassiède M. , Shaw J. M.
Published: April 2015

Two parallel multi-element ultrasonic acoustic arrays combined with sets of focal laws for acoustic signal generation and a classical tomographic inversion algorithm are used to generate real-time two-dimensional micro seismic acoustic images of multiphase materials. Proof of concept and calibration measurements were performed for single phase and two phase liquids, uniform polyvinyl chloride (PVC) plates, and aluminum cylinders imbedded in PVC plates. Measurement artefacts, arising from the limited range of viewing angles, and the compromise between data acquisition rate and image quality are discussed. The angle range of scanning and the image resolution were varied, and the effects on the quality of the reproduction of the speed of sound profiles of model solids and liquids with known geometries and compositions were analysed in detail. The best image quality results were obtained for a scanning angle range of [−35°, 35°] at a step size of 2.5° post processed to generate images on a 40 μm square grid. The data acquisition time for high quality images with a 30 mm × 40 mm view field is 10 min. Representation of two-phase solids with large differences in speed of sound between phases and where one phase is dispersed in the form of macroscopic objects (greater than 1 mm in diameter) proved to be the most difficult to image accurately. Liquid-liquid and liquid-vapor phase boundaries, in micro porous solids by contrast, were more readily defined. Displacement of air by water and water by heptane in natural porous limestone provides illustrative kinetic examples. Measurement results with these realistic cases demonstrate the feasibility of the technique to monitor in real time and on the micrometer length scale local composition and flow of organic liquids in inorganic porous media, one of many envisioned engineering applications. Improvement of data acquisition rate is an area for future collaborative study.
A simple Boltzmann transport equation for ballistic to diffusive transient heat transport
Authors: Maassen Jesse , Lundstrom Mark
Published: April 2015

Developing simplified, but accurate, theoretical approaches to treat heat transport on all length and time scales is needed to further enable scientific insight and technology innovation. Using a simplified form of the Boltzmann transport equation (BTE), originally developed for electron transport, we demonstrate how ballistic phonon effects and finite-velocity propagation are easily and naturally captured. We show how this approach compares well to the phonon BTE, and readily handles a full phonon dispersion and energy-dependent mean-free-path. This study of transient heat transport shows (i) how fundamental temperature jumps at the contacts depend simply on the ballistic thermal resistance, (ii) that phonon transport at early times approach the ballistic limit in samples of any length, and (iii) perceived reductions in heat conduction, when ballistic effects are present, originate from reductions in temperature gradient. Importantly, this framework can be recast exactly as the Cattaneo and hyperbolic heat equations, and we discuss how the key to capturing ballistic heat effects is to use the correct physical boundary conditions.
Frequency non-degenerate sequential excitation of the impurity trapped exciton in strontium fluoride crystals doped with ytterbium
Authors: Senanayake Pubudu S. , Wells Jon-Paul R. , Reid Michael F. , Hughes-Currie Rosa B. , Berden Giel , Reeves Roger J. , Meijerink Andries
Published: April 2015

We model the dynamic behaviour observed for impurity-trapped excitons in SrF2:Yb2+ using transient photoluminescence enhancement induced via a two-frequency, sequential excitation process employing an UV optical parametric amplifier synchronized to an IR free electron laser (FEL). We observe sharp transitions interpreted as a change of state of the localized hole and broad bands interpreted as a change of state of the delocalized electron. Our modeling indicates that the 4f crystal-field interaction is 25% smaller than in CaF2. The photoluminescence enhancement transients are analyzed across a range of excitation frequencies using a system of rate equations. The temporal behavior is explained in terms of intra-excitonic relaxation, local lattice heating by the FEL, and liberation of electrons from trap states.
From charge motion in general magnetic fields to the non perturbative gyrokinetic equation
Authors: Di Troia C.
Published: April 2015

The exact analytical description of non relativistic charge motion in general magnetic fields is, apparently, a simple problem, even if it has not been solved until now, apart for rare cases. The key feature of the present derivation is to adopt a non perturbative magnetic field description to find new solutions of motion. Among all solutions, two are particularly important: guiding particle and gyro-particle solutions. The guiding particle has been characterized to be minimally coupled to the magnetic field; the gyro-particle has been defined to be maximally coupled to the magnetic field and, also, to move on a closed orbit. The generic charged particle motion is shown to be expressed as the sum of such particular solutions. This non perturbative approach corresponds to the description of the particle motion in the gyro-center and/or guiding center reference frame obtained at all the orders of the modern gyro-center transformation. The Boltzmann equation is analyzed with the described exact guiding center coordinates. The obtained gyrokinetic equation is solved for the Boltzmann equation at marginal stability conditions.
Thermal stability of vapor-deposited stable glasses of an organic semiconductor
Authors: Walters Diane M. , Richert Ranko , Ediger M. D.
Published: April 2015

Vapor-deposited organic glasses can show enhanced kinetic stability relative to liquid-cooled glasses. When such stable glasses of model glassformers are annealed above the glass transition temperature Tg, they lose their thermal stability and transform into the supercooled liquid via constant velocity propagating fronts. In this work, we show that vapor-deposited glasses of an organic semiconductor, N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD), also transform via propagating fronts. Using spectroscopic ellipsometry and a new high-throughput annealing protocol, we measure transformation front velocities for TPD glasses prepared with substrate temperatures (TSubstrate) from 0.63 to 0.96 Tg, at many different annealing temperatures. We observe that the front velocity varies by over an order of magnitude with TSubstrate, while the activation energy remains constant. Using dielectric spectroscopy, we measure the structural relaxation time of supercooled TPD. We find that the mobility of the liquid and the structure of the glass are independent factors in controlling the thermal stability of TPD films. In comparison to model glassformers, the transformation fronts of TPD have similar velocities and a similar dependence on TSubstrate, suggesting universal behavior. These results may aid in designing active layers in organic electronic devices with improved thermal stability.
Improved performance in GaInNAs solar cells by hydrogen passivation
Authors: Fukuda M. , Whiteside V. R. , Keay J. C. , Meleco A. , Sellers I. R. , Hossain K. , Golding T. D. , Leroux M. , Al Khalfioui M.
Published: April 2015

The effect of UV-activated hydrogenation on the performance of GaInNAs solar cells is presented. A proof-of-principle investigation was performed on non-optimum GaInNAs cells, which allowed a clearer investigation of the role of passivation on the intrinsic nitrogen-related defects in these materials. Upon optimized hydrogenation of GaInNAs, a significant reduction in the presence of defect and impurity based luminescence is observed as compared to that of unpassivated reference material. This improvement in the optical properties is directly transferred to an improved performance in solar cell operation, with a more than two-fold improvement in the external quantum efficiency and short circuit current density upon hydrogenation. Temperature dependent photovoltaic measurements indicate a strong contribution of carrier localization and detrapping processes, with non-radiative processes dominating in the reference materials, and evidence for additional strong radiative losses in the hydrogenated solar cells.
A recoil ion momentum spectrometer for molecular and atomic fragmentation studies
Authors: Khan Arnab , Tribedi Lokesh C. , Misra Deepankar
Published: April 2015

We report the development and performance studies of a newly built recoil ion momentum spectrometer for the study of atomic and molecular fragmentation dynamics in gas phase upon the impact of charged particles and photons. The present design is a two-stage Wiley-McLaren type spectrometer which satisfies both time and velocity focusing conditions and is capable of measuring singly charged ionic fragments up-to 13 eV in all directions. An electrostatic lens has been introduced in order to achieve velocity imaging. Effects of the lens on time-of-flight as well as on the position have been investigated in detail, both, by simulation and in experiment. We have used 120 keV proton beam on molecular nitrogen gas target. Complete momentum distributions and kinetic energy release distributions have been derived from the measured position and time-of-flight spectra. Along with this, the kinetic energy release spectra of fragmentation of doubly ionized nitrogen molecule upon various projectile impacts are presented.
The origin of ferroelectricity in Hf1−xZrxO2: A computational investigation and a surface energy model
Authors: Materlik R. , Künneth C. , Kersch A.
Published: April 2015

The structural, thermal, and dielectric properties of the ferroelectric phase of HfO2, ZrO2, and Hf0.5Zr0.5O2 (HZO) are investigated with carefully validated density functional computations. We find that the free bulk energy of the ferroelectric orthorhombic Pca21 phase is unfavorable compared to the monoclinic P21/c and the orthorhombic Pbca phase for all investigated stoichiometries in the Hf1−xZrxO2 system. To explain the existence of the ferroelectric phase in nanoscale thin films, we explore the Gibbs/Helmholtz free energies as a function of stress and film strain and find them unlikely to become minimal in HZO films for technological relevant conditions. To assess the contribution of surface energy to the phase stability, we parameterize a model, interpolating between existing data, and find the Helmholtz free energy of ferroelectric grains minimal for a range of size and stoichiometry. From the model, we predict undoped HfO2 to be ferroelectric for a grain size of about 4 nm and epitaxial HZO below 5 nm. Furthermore, we calculate the strength of an applied electric field necessary to cause the antiferroelectric phase transformation in ZrO2 from the P42/nmc phase as 1 MV/cm in agreement with experimental data, explaining the mechanism of field induced phase transformation.
Non-degenerate four-wave mixing in an optically injection-locked InAs/InP quantum dot Fabry–Perot laser
Authors: Huang H. , Schires K. , Poole P. J. , Grillot F.
Published: April 2015

Non-degenerate four-wave mixing in an InAs/InP quantum dot Fabry–Perot laser is investigated with an optical injection-locking scheme. Wavelength conversion is obtained for frequency detunings ranging from +2.5 THz to −3.5 THz. The normalized conversion efficiency is maintained above −40 dB between −1.5 and +0.5 THz with an optical signal-to-noise ratio above 20 dB and a maximal third-order nonlinear susceptibility normalized to material gain of 2 × 10−19 m3/V2. In addition, we show that injection-locking at different positions in the gain spectrum has an impact on the nonlinear conversion process and the symmetry between up- and down- converted signals.
Orientational order as the origin of the long-range hydrophobic effect
Authors: Banerjee Saikat , Singh Rakesh S. , Bagchi Biman
Published: April 2015

The long range attractive force between two hydrophobic surfaces immersed in water is observed to decrease exponentially with their separation—this distance-dependence of effective force is known as the hydrophobic force law (HFL). We explore the microscopic origin of HFL by studying distance-dependent attraction between two parallel rods immersed in 2D Mercedes Benz model of water. This model is found to exhibit a well-defined HFL. Although the phenomenon is conventionally explained by density-dependent theories, we identify orientation, rather than density, as the relevant order parameter. The range of density variation is noticeably shorter than that of orientational heterogeneity. The latter is comparable to the observed distances of hydrophobic force. At large separation, attraction between the rods arises primarily from a destructive interference among the inwardly propagating oppositely oriented heterogeneity generated in water by the two rods. As the rods are brought closer, the interference increases leading to a decrease in heterogeneity and concomitant decrease in free energy of the system, giving rise to the effective attraction. We notice formation of hexagonal ice-like structures at the onset of attractive region which suggests that metastable free energy minimum may play a role in the origin of HFL.
Magnetogenesis through convection in barotropic fluids
Authors: Miller E. , Rogers B.
Published: April 2015

It is shown that an unmagnetized plasma with non-uniform bulk velocity can generate magnetic fields through consideration of the non-relativistic isentropic two-fluid equations, even when the initial conditions contain with no fields or currents, uniform densities and pressures, and a divergence-free bulk velocity. This effect does not depend on the baroclinicity of the plasma and is therefore relevant even in barotropic flows, where the Biermann battery is absent. It also does not rely on kinetic effects or shear discontinuities. Instead, our magnetogenesis effect arises from convection terms proportional to the electron mass in the generalized Ohm's law. The resulting magnetic fields are typically weak but may still serve as seed fields for dynamo mechanisms.
Chemical and structural effects on the high-temperature mechanical behavior of (1−x)(Na1/2Bi1/2)TiO3-xBaTiO3 ceramics
Authors: Deluca Marco , Picht Gunnar , Hoffmann Michael J. , Rechtenbach Annett , Töpfer Jörg , Schader Florian H. , Webber Kyle G.
Published: April 2015

Bismuth sodium titanate–barium titanate [(1−x)(Na1/2Bi1/2)TiO3-xBaTiO3, NBT-100xBT] is one of the most well studied lead-free piezoelectric materials due in large part to the high field-induced strain attainable in compositions near the morphotropic phase boundary (x = 0.06). The BaTiO3-rich side of the phase diagram, however, has not yet been as comprehensively studied, although it might be important for piezoelectric and positive temperature coefficient ceramic applications. In this work, we present a thorough study of BaTiO3-rich NBT-100xBT by ferroelastic measurements, dielectric permittivity, X-ray diffraction, and Raman spectroscopy. We show that the high-temperature mechanical behavior, i.e., above the Curie temperature, TC, is influenced by local disorder, which appears also in pure BT. On the other hand, in NBT-100xBT (x < 1.0), lattice distortion, i.e., tetragonality, increases, and this impacts both the mechanical and dielectric properties. This increase in lattice distortion upon chemical substitution is counterintuitive by merely reasoning on the ionic size, and is due to the change in the A-O bond character induced by the Bi3+ electron lone pair, as indicated by Raman spectroscopy.