bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural response during attentional control and emotion processing predicts improvement after cognitive behavioral therapy in generalized social anxiety disorder
Authors: Klumpp H. , Fitzgerald D. A. , Angstadt M. , Post D. , Phan K. L.
Published: March 2014

Background

Individuals with generalized social anxiety disorder (gSAD) exhibit attentional bias to salient stimuli, which is reduced in patients whose symptoms improve after treatment, indicating that mechanisms of bias mediate treatment success. Therefore, pre-treatment activity in regions implicated in attentional control over socio-emotional signals (e.g. anterior cingulate cortex, dorsolateral prefrontal cortex) may predict response to cognitive behavioral therapy (CBT), evidence-based psychotherapy for gSAD.

Method

During functional magnetic resonance imaging, 21 participants with gSAD viewed images comprising a trio of geometric shapes (circles, rectangles or triangles) alongside a trio of faces (angry, fearful or happy) within the same field of view. Attentional control was evaluated with the instruction to ‘match shapes’, directing attention away from faces, which was contrasted with ‘match faces’, whereby attention was directed to emotional faces.

Results

Whole-brain voxel-wise analyses showed that symptom improvement was predicted by enhanced pre-treatment activity in the presence of emotional face distractors in the dorsal anterior cingulate cortex and dorsal medial prefrontal cortex. Additionally, CBT success was foretold by less activity in the amygdala and/or increased activity in the medial orbitofrontal gyrus during emotion processing.

Conclusions

CBT response was predicted by pre-treatment activity in prefrontal regions and the amygdala. The direction of activity suggests that individuals with intact attentional control in the presence of emotional distractors, regulatory capacity over emotional faces and/or less reactivity to such faces are more likely to benefit from CBT. Findings indicate that baseline neural activity in the context of attentional control and emotion processing may serve as a step towards delineating mechanisms by which CBT exerts its effects.
Secondary removal ofMyristica fatua(Myristicaceae) seeds by crabs inMyristicaswamp forests in India
Authors: Krishna Shivani , Somanathan Hema
Published: March 2014

Little is known about the role of crabs as seed dispersers and predators. Recently, there has been interest in understanding their influence on plant recruitment in coastal forests. Secondary seed removal by crabs in a swamp-specialist tree,Myristica fatua, was investigated in the rare and patchy freshwaterMyristicaswamps in the Western Ghats in India. Tethered-line experiments were used to determine the role of crabs as secondary seed-removal agents in two study sites. Crabs transported a large percentage (63.3%) of seeds (n = 60) placed on the forest floor compared with rodents (25%) and other unknown agents (13.3%). Simultaneous choice experiments suggested that the nutrient-rich arils covering seeds were consumed, but there was no evidence for seed predation by crabs. A small percentage (13.3%) of monitored seeds (n = 60) germinated from within crab burrows. The spatial scale of secondary removal by crabs was restricted to < 10 m. In these fragmented swamp forests, secondary removal by crabs retains seeds largely within the swamps, where conditions for their establishment and survival are optimal. Thus, secondary seed removal by crabs could provide temporal and spatial refugia from seed predators such as rodents inMyristica fatua.
Semantic composition of business processes using Armstrong's Axioms
Authors: Celik Duygu , Elci Atilla
Published: March 2014

Lack of sufficient semantic description in the content of Web services makes it difficult to find and compose suitable Web services during analysis, search, and matching processes. Semantic Web Services are Web services that have been enhanced with formal semantic description, which provides well-defined meaning. Due to insertion of semantics, meeting user demands will be made possible through logical deductions achieving resolutions automatically. We have developed an inference-based semantic business process composition agent (SCA) that employs inference techniques. The semantic composition agent system is responsible for the synthesis of new services from existing ones in a semi-automatic fashion. SCA System composes available Web Ontology Language for Web services atomic processes utilizing Revised Armstrong's Axioms (RAAs) in inferring functional dependencies. RAAs are embedded in the knowledge base ontologies of SCA System. Experiments show that the proposed SCA System produces process sequences as a composition plan that satisfies user's requirement for a complex task. The novelty of the SCA System is that for the first time Armstrong's Axioms are revised and used for semantic-based planning and inferencing of Web services.
Stallings graphs, algebraic extensions and primitive elements in F2
Authors: PARZANCHEVSKI ORI , PUDER DORON
Published: March 2014

We study the free group of rank two from the point of view of Stallings core graphs. The first half of the paper examines primitive elements in this group, giving new and self-contained proofs for various known results about them. In particular, this includes the classification of bases of this group. The second half of the paper is devoted to constructing a counterexample to a conjecture by Miasnikov, Ventura and Weil, which seeks to characterize algebraic extensions in free groups in terms of Stallings graphs.
Ardelia Hall: From Museum of Fine Arts to Monuments Woman
Authors: Reed Victoria
Published: March 2014

Ardelia Ripley Hall (1899–1979) served from 1946 until 1962 as the Fine Arts and Monuments Adviser to the U.S. Department of State. In this role she oversaw the recovery and restitution of movable cultural property that had been displaced during the Second World War. In spite of her vast accomplishments, almost nothing has been written on Ardelia Hall, and little is known about her life. She began her career at the Museum of Fine Arts, Boston, but personal circumstances led to her resignation in 1941. During the war, she was employed by the Office of Strategic Services. The expertise she established as an art historian working with the Roberts Commission at this time led to her appointment at the State Department in 1946. This essay traces for the first time Hall’s remarkable journey from curatorial researcher to adviser on international art restitution.
Random field representations for stochastic elliptic boundary value problems and statistical inverse problems
Authors: NOUY A. , SOIZE C.
Published: March 2014

This paper presents new results allowing an unknown non-Gaussian positive matrix-valued random field to be identified through a stochastic elliptic boundary value problem, solving a statistical inverse problem. A new general class of non-Gaussian positive-definite matrix-valued random fields, adapted to the statistical inverse problems in high stochastic dimension for their experimental identification, is introduced and its properties are analysed. A minimal parameterisation of discretised random fields belonging to this general class is proposed. Using this parameterisation of the general class, a complete identification procedure is proposed. New results of the mathematical and numerical analyses of the parameterised stochastic elliptic boundary value problem are presented. The numerical solution of this parametric stochastic problem provides an explicit approximation of the application that maps the parameterised general class of random fields to the corresponding set of random solutions. This approximation can be used during the identification procedure in order to avoid the solution of multiple forward stochastic problems. Since the proposed general class of random fields possibly contains random fields which are not uniformly bounded, a particular mathematical analysis is developed and dedicated approximation methods are introduced. In order to obtain an algorithm for constructing the approximation of a very high-dimensional map, complexity reduction methods are introduced and are based on the use of sparse or low-rank approximation methods that exploit the tensor structure of the solution which results from the parameterisation of the general class of random fields.
Measuring Surface Atom Bond Length Contraction in Au and Pt Nanoparticles Using High-Precision STEM Imaging
Authors: Yankovich A.B. , Berkels B. , Dahmen W. , Sharpley R. , Binev P. , Voyles P.
Published: March 2014

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
When Being a Bad Friend Doesn’t Hurt
Authors: Szücs Attila , Schindler Simon , Reinhard Marc-André , Stahlberg Dagmar
Published: March 2014

Research on domain-specific sociometer theory suggests that individual mate value has a great influence on self-esteem. In this study (N = 124), we investigated the notion that perceived high gender typicality increases one’s perceived mate value and thus counteracts the usual decline in state self-esteem following negative feedback. The participants completed a fictitious personality test to assess their individual quality as a friend and received bogus negative feedback. Depending on the experimental condition, participants received a test score close to the mean test score attained by their own or the opposite gender and thus either gender-typical or gender-atypical. Additionally, we included a control condition in which no feedback was given. The results showed that participants in the gender-atypical condition reported lower state self-esteem than did participants in the gender-typical condition or the control condition. This buffer effect was mediated by perceived mate value.
Microstructured fiber@HZSM-5 core–shell catalysts with dramatic selectivity and stability improvement for the methanol-to-propylene process
Authors: Wang Xiangyu , Wen Ming , Wang Chunzheng , Ding Jia , Sun Ying , Liu Ye , Lu Yong
Published: March 2014

Dramatic selectivity and stability improvement of ZSM-5 zeolite for the methanol-to-propylene process has been achieved by a solely microstructured core–shell catalyst design.
Acoustic actuated fluorescence activated sorting of microparticles
Authors: Jakobsson Ola , Grenvall Carl , Nordin Maria , Evander Mikael , Laurell Thomas
Published: March 2014

In this paper, we present a fluorescence activated sorter realized in a continuous flow microfluidic chip.
A self-powered ultraviolet detector based on a single ZnO microwire/p-Si film with double heterojunctions
Authors: Qi Junjie , Hu Xiaofeng , Wang Zengze , Li Xin , Liu Wang , Zhang Yue
Published: March 2014

A high performance self-powered ultraviolet detector based on a single ZnO microwire/p-Si film with double heterojunctions was fabricated.
Synthesis and electrochemical properties of silicon nanosheets by DC arc discharge for lithium-ion batteries
Authors: Yu Xiuhong , Xue Fanghong , Huang Hao , Liu Chunjing , Yu Jieyi , Sun Yuejun , Dong Xinglong , Cao Guozhong , Jung Youngguan
Published: March 2014

We synthesized 2D Si nanostructure with thickness less than 8 atomic layers at large scale by DC arc discharge method.
Synthesis of RAFT polymers as bivalent inhibitors of cholera toxin
Authors: Leaver David J. , Hughes Andrew B. , Dawson Raymond M. , Postma Almar , Malic Nino , Polyzos Anastasios
Published: March 2014

We report a new strategy to develop low molecular weight (18–28 kDa) poly(N-acryloylmorpholine) (PNAM) polymers as bivalent inhibitors of cholera toxin (CT) using Reversible Addition–Fragmentation chain Transfer (RAFT) technology.
A real time affinity biosensor on an insulated polymer using electric impedance spectroscopy in dielectric microchips
Authors: Kechadi Mohammed , Sotta Bruno , Chaal Lila , Tribollet Bernard , Gamby Jean
Published: March 2014

This paper demonstrates how a contactless microelectrode allows monitoring of the electric impedance changes provoked by the association of two protein ligands.
A ratiometric fluorescent probe for the detection of hydroxyl radicals in living cells
Authors: Meng Luyan , Wu Yongquan , Yi Tao
Published: March 2014

A naphthalimide–naphthyridine derivative is reported for the selective detection of hydroxyl radicals in both solution and living cells.
A diazirine-based photoaffinity probe for facile and efficient aptamer–protein covalent conjugation
Authors: Zhang Huimin , Song Yanling , Zou Yuan , Ge Yun , An Yuan , Ma Yanli , Zhu Zhi , Yang Chaoyong James
Published: March 2014

A photo-reactive functional labelling reagent was designed and synthesized for site-specific labelling of oligonucleotide with the diazirine moiety for facile and efficient photo-crosslinking of the resulting oligonucleotide with its interacting partner for a variety of applications.
Four new metal–organic frameworks based on a rigid linear ligand: synthesis, optical properties and structural investigation
Authors: Zhang Chuanlei , Hao Han , Shi Zhenzhen , Zheng Hegen
Published: March 2014

Four coordination polymers have been synthesized based on a rigid linear carboxylate ligand and different lengths of imidazole ligands.
Rigid yet flexible heteroleptic Co(iii) dipyrrin complexes for the construction of heterometallic 1- and 2-D coordination polymers
Authors: Béziau Antoine , Baudron Stéphane A. , Rasoloarison Dimby , Hosseini Mir Wais
Published: March 2014

Acetylacetonate Co(iii)–dipyrrin complexes form flexible metallatectons displaying diverse shapes when combined with CdX2salts.
2D → 2D Parallel interpenetration of (4,4) sheets constructed from a ditopic bis(4,2′:6′,4′′-terpyridine)
Authors: Constable Edwin C. , Housecroft Catherine E. , Vujovic Srboljub , Zampese Jennifer A.
Published: March 2014

1,4-Bis(n-octyloxy)-2,5-bis(4,2′:6′,4′′-terpyridin-4′-yl)benzene reacts with ZnCl2 to give corrugated 2D (4,4) nets which interpenetrate in a 2D → 2D parallel manner.
An ab initio MO study of heavy atom effects on the zero-field splitting tensors of high-spin nitrenes: how the spin–orbit contributions are affected
Authors: Sugisaki Kenji , Toyota Kazuo , Sato Kazunobu , Shiomi Daisuke , Kitagawa Masahiro , Takui Takeji
Published: March 2014

The CASSCF and hybrid CASSCF–MRMP2 methods reproduce the ZFS tensors of spin-septet 2,4,6-trinitrenopyridines, focusing on the heavy atom effects on the spin–orbit terms of the tensors.
Methane storage in metal–organic frameworks
Authors: He Yabing , Zhou Wei , Qian Guodong , Chen Banglin
Published: March 2014

Porous metal–organic frameworks have been emerging as very promising materials for methane (natural gas) storage.
Effects of benzo-annelation of asymmetric phthalocyanine on the photovoltaic performance of dye-sensitized solar cells
Authors: Yu Lijuan , Shi Wenye , Lin Li , Liu Yuwen , Li Renjie , Peng Tianyou , Li Xingguo
Published: March 2014

Novel highly asymmetric zinc tetraazaporphyrin (TAP) derivatives (Zn-tri-TAPNc and Zn-tri-PcNc) with one carboxyl and three tert-butyl peripheral substituent groups for dye-sensitized solar cells were synthesized.
Boosting the salt recognition abilities of l-ornithine based multitopic molecular receptors by harnessing a double cooperative effect
Authors: Piątek Piotr , Karbarz Marcin , Romański Jan
Published: March 2014

Systematic development of the geometric and electronic properties of the amino acid based salt receptors leads to a very effective and selective NaNO2 receptor.
Structure activity relationship study of mezzettiasides natural products and their four new disaccharide analogues for anticancer/antibacterial activity
Authors: Bajaj Sumit O. , Shi Pei , Beuning Penny J. , O'Doherty George A.
Published: March 2014

Ten members of the mezzettiaside family of natural products were synthesized and evaluated for anticancer and antibacterial activity.
Multifunctional Fe3O4@TiO2@Au magnetic microspheres as recyclable substrates for surface-enhanced Raman scattering
Authors: Zhang Xiaoqing , Zhu Yihua , Yang Xiaoling , Zhou Ying , Yao Yifan , Li Chunzhong
Published: March 2014

Fabrication of multifunctional Fe3O4@TiO2@Au magnetic microspheres with controlled size and areal density of Au nanoparticles and their application as recyclable substrates for surface-enhanced Raman scattering.
Synthesis and biological evaluation of dual actioncyclo-RGD/SMAC mimetic conjugates targeting αvβ3/αvβ5integrins and IAP proteins
Authors: Mingozzi M. , Manzoni L. , Arosio D. , Dal Corso A. , Manzotti M. , Innamorati F. , Pignataro L. , Lecis D. , Delia D. , Seneci P. , Gennari C.
Published: March 2014

Dual actioncyclo-RGD/SMAC mimetic conjugates endowed within vitroactivity against anti-apoptotic IAPs and pro-angiogenetic integrins are reported.
Exploiting end group functionalization for the design of antifouling bioactive brushes
Authors: Kuzmyn A. R. , de los Santos Pereira A. , Pop-Georgievski O. , Bruns M. , Brynda E. , Rodriguez-Emmenegger C.
Published: March 2014

The Diels–Alder reaction between cyclopentadiene and maleimide is exploited to immobilize proteins on the chain-end of polymer brushes.
Observing wetting behaviors of UV-curable liquid on nanostructured surfaces with sub-20 nm resolution
Authors: Bian Jie , Fu Xinxin , Hu Jing , Cui Yushuang , Li Zhiwei , Yuan Changsheng , Ge Haixiong , Li Wen-Di , Chen Yanfeng
Published: March 2014

In this work, the liquid acrylated materials were transferred onto the nanostructured surfaces by a transfer printing method.
Enhanced hydrogen storage properties of LiAlH4 catalyzed by CoFe2O4 nanoparticles
Authors: Li Ziliang , Zhai Fuqiang , Wan Qi , Liu Zhaojiang , Shan Jiawei , Li Ping , Volinsky Alex A. , Qu Xuanhui
Published: March 2014

The catalytic effects of CoFe2O4 nanoparticles on the hydrogen storage properties of LiAlH4 prepared by ball milling were investigated.
Novel NLO-phores containing dihexyl amino benzo[b]thiophene exhibiting good transparency and enhanced electro-optical activity
Authors: Zhang Maolin , Xu Huajun , Peng Chengcheng , Huang Heyan , Bo Shuhui , Liu Jialei , Liu Xinhou , Zhen Zhen , Qiu Ling
Published: March 2014

Two new chromophores (A and B) were synthesized, in which a benzo[b]thiophene moiety was first introduced as a donor group.
Ternary alloy nanocrystals of tin and germanium chalcogenides
Authors: Im Hyung Soon , Myung Yoon , Park Kidong , Jung Chan Su , Lim Young Rok , Jang Dong Myung , Park Jeunghee
Published: March 2014

SnxGe1−xS, SnxGe1−xSe, GeSxSe1−x, and SnSxSe1−x alloy nanocrystals were synthesized by novel gas-phase laser photolysis. Their composition-dependent lattice parameters and band gap were thoroughly characterized. The SnxGe1−xS and SnSxSe1−x nanocrystals exhibit higher photoconversion efficiency as compared with the end members.
Molecular iodine induced/1,3-dipolar cycloaddition/oxidative aromatization sequence: an efficient strategy to construct 2-substituted benzo[f]isoindole-1,3-dicarboxylates
Authors: Huang Huan-Ming , Gao Jian-Rong , Ye Qing , Yu Wu-Bin , Sheng Wei-Jian , Li Yu-Jin
Published: March 2014

A useful method for a molecular iodine induced 1,3-dipolar cycloaddition/oxidative aromatization sequence to construct 2-substituted-benzo[f]isoindole-1,3-dicarboxylates is reported.
Pushing for particulate level models of adiabatic and isothermal processes in upper-level chemistry courses: a qualitative study
Authors: Hernández Gabriel E. , Criswell Brett A. , Kirk Nancy J. , Sauder Deborah G. , Rushton Gregory T.
Published: March 2014

In the past three decades, researchers have noted the limitations of a problem-solving approach that overemphasizes algorithms and quantitation and neglects student misconceptions and an otherwise qualitative, conceptual understanding of chemical phenomena. Since then, studies and lessons designed to improve student understanding of chemistry has overwhelmingly targeted introductory level, high school and first-year college students. In this article, we present a model-based learning cycle approach with upper-level undergraduate and beginning graduate students that investigated their ability to model the adiabatic and isothermal compression/expansion of a gas in a syringe. We were interested to observe, given the extent of their previous chemistry coursework, how students struggled to connect macroscopic observations with particulate representations. Analysis of laboratory reports, reflective journal entries, and classroom discourse transcripts indicate the learning experience was efficacious in uncovering and addressing student conceptual challenges with using models appropriately to describe gas behaviour under the experimental conditions for this investigation.
A multi-photoresponsive supramolecular hydrogel with dual-color fluorescence and dual-modal photodynamic action
Authors: Fraix Aurore , Gref Ruxandra , Sortino Salvatore
Published: March 2014

The self-assembly of four different components forms a supramolecular hydrogel exhibiting green and red fluorescence and releasing two powerful anticancer species upon illumination with visible light.
Flash memory based on solution processed hafnium dioxide charge trapping layer
Authors: Zhuang Jiaqing , Han Su-Ting , Zhou Ye , Roy V. A. L.
Published: March 2014

Hafnium dioxide (HfO2) film prepared by the sol–gel technique has been used as a charge trapping layer in organic flash memory.
Facile route to synthesise larger mesoporous nickel silicate coated on carbon nanotubes and application for dye removal
Authors: Xia Peixiong , Zhang Min , Zheng Jing , Zheng Yue , Xu Jingli
Published: March 2014

Presented is a facile route to synthesise mesoporous nickel silicate coated on carbon nanotubes (CNTs) with a larger hole based on the mesoporous silica coated on the CNTs, the pore size of the mesoporous silica coated on the CNTs was enlarged from 2.72 to 7.8 nm after a hydrothermal reaction with nickel ions. Compared with other work for expanding the size of the pore, the authors’ presented method is low cost, simple and highly efficient. More importantly, this method shows great potential in applying other types of mesoporous materials such as SBA‐15 and so on, all of which indicate that both the mesoporous nickel silicate coated on the CNTs and the mesoporous silica coated on the CNTs could serve as good candidates for adsorption on the organic pollutants.
Synthesis and characterisation of magnetic‐fluorescent Fe3O4@SiO2@ZnS nanocomposites
Authors: Jiang Caidi , Mo Zunli , Pu Bin , Zhang Chun
Published: March 2014

Bifunctional magnetic‐fluorescent Fe3O4@SiO2@ZnS nanocomposites were synthesised by a chemical deposition method. The Fe3O4 magnetic nanoparticles as the core were obtained by means of a solvothermal reaction with SiO2 as the shell. ZnS particles were linked to Fe3O4@SiO2 core–shell nanostructures. The morphology and properties of the resultant Fe3O4@SiO2@ZnS nanocomposites were investigated by X‐ray diffraction, field emission scanning electron microscopy, high‐resolution transmission electron microscopy, a vibration sample magnetometer and fluorescence microscopy. The results showed that bead‐like structures were built from numerous Fe3O4@SiO2@ZnS microspheres with an average size of 250 nm. The saturation magnetisation (Ms) value of Fe3O4@SiO2@ZnS nanocomposites was 22.41 emu/g at room temperature. Furthermore, a strong blue light emission was observed from the nanocomposites under UV light irradiation. The combination of magnetic and fluorescent properties may lead to Fe3O4@SiO2@ZnS nanocomposites having a variety of potential applications in the field of biomedicine, such as bioimaging and cell separation.
Threshold voltage study of scaled self‐aligned In0.53Ga0.47As metal oxide semiconductor field effect transistor for different source/drain doping concentrations
Authors: Dehzangi A. , Razip Wee M.F. Mohd , Wichmann N. , Bollaert S. , Buyong M.R. , Majlis B.Y.
Published: March 2014

A multi‐gate n‐type In0.53Ga0.47As metal oxide semiconductor field effect transistor is fabricated using the gate first self‐aligned method and air‐bridge technology with an 8 nm thick Al2O3 oxide layer. By scaling the gate length down to 200 nm, the effect of two different source/drain doping concentrations on device parameters such as threshold voltage, Ion/Ioff ratio and subthreshold swing were investigated at room temperature. Increasing the value of the source/drain doping concentration revealed an enhancement in all investigated parameters. Sheet resistance and contact resistance values were improved as well. The negative shift in threshold voltage for shorter gate lengths was observed for both source/drain concentrations; however, the shift in threshold voltage was less (∼0.4 V) for the higher source/drain doping concentration.
Creation and measurement of nanodots with combined dynamic mode ‘dip‐pen’ nanolithography based on atomic force microscope
Authors: Cui Jianlei , Yang Lijun , Wang Yang
Published: March 2014

Dip‐pen nanolithography (DPN), based on atomic force microscope (AFM) system, is an effective method for nanoscale science and engineering and the potential applications of DPN feature in the fields of nanomechanics, nanomaterials, nanobiotechnology and nanomedicine and combined dynamic mode DPN, rather than the often used contact mode DPN or the tapping mode DPN, becomes an important tool for the creation of nanodots with the direct writing method of depositing the ink onto the hard silicon surface at the predetermined position with a very high resolution, which is presented in the corresponding experiments. For a better nanolithography quality of the nanodot, the nanolithography process, under the optimised process parameters, is accomplished once without the intermediate scan imaging process as much as possible. In addition, the size of the nanodots subsequently decreases with the increase of the number of the nanodots in the case of the AFM tip dipping in ink once. Consequently, for the creation of a nanodot within the controllable mass, the measurement scheme about the deposition mass of ink, theoretically analysed and experimentally achieved in the aspect of quantification, is also proposed in this Letter.
Optical and magneto-optical properties of Co-doped CeO2−δ films in the 0.5 to 4 eV range
Authors: Veis M. , Kucera M. , Zahradnik M. , Antos R. , Mistrik J. , Bi Lei , Kim Hyun-Suk , Dionne G. F. , Ross C. A.
Published: March 2014

Magnetically doped Ce1−xCoxO2−δ (nominal x = 0.05 and 0.10) films were systematically studied by spectroscopic ellipsometry and magneto-optical spectroscopy. The samples were prepared by pulsed laser deposition on MgO(100) substrates and grew as textured polycrystalline films with thickness between 200 and 750 nm. They exhibited room temperature ferromagnetism and an out-of-plane easy axis attributed to magnetoelastic effects from the in-plane compressive strain. The dispersion of dielectric function of Ce1−xCoxO2−δ films was parametrized by the sum of Tauc-Lorentz and damped Lorentz oscillators and adjusted numerically. Deduced optical band gaps were similar to those of pure CeO2, but the Co doping increased the optical absorption. The magneto-optical spectroscopy was carried out in both Faraday and Kerr configurations in the photon energy range from 0.5 to 4 eV, showing a strong dependence of the magneto-optical effect on the Co content near the optical band edge.
Local packing modulates diversity of iron pathways and cooperative behavior in eukaryotic and prokaryotic ferritins
Authors: Ruvinsky Anatoly M. , Vakser Ilya A. , Rivera Mario
Published: March 2014

Ferritin-like molecules show a remarkable combination of the evolutionary conserved activity of iron uptake and release that engage different pores in the conserved ferritin shell. It was hypothesized that pore selection and iron traffic depend on dynamic allostery with no conformational changes in the backbone. In this study, we detect the allosteric networks in Pseudomonas aeruginosa bacterioferritin (BfrB), bacterial ferritin (FtnA), and bullfrog M and L ferritins (Ftns) by a network-weaving algorithm (NWA) that passes threads of an allosteric network through highly correlated residues using hierarchical clustering. The residue-residue correlations are calculated in the packing-on elastic network model that introduces atom packing into the common packing-off model. Applying NWA revealed that each of the molecules has an extended allosteric network mostly buried inside the ferritin shell. The structure of the networks is consistent with experimental observations of iron transport: The allosteric networks in BfrB and FtnA connect the ferroxidase center with the 4-fold pores and B-pores, leaving the 3-fold pores unengaged. In contrast, the allosteric network directly links the 3-fold pores with the 4-fold pores in M and L Ftns. The majority of the network residues are either on the inner surface or buried inside the subunit fold or at the subunit interfaces. We hypothesize that the ferritin structures evolved in a way to limit the influence of functionally unrelated events in the cytoplasm on the allosteric network to maintain stability of the translocation mechanisms. We showed that the residue-residue correlations and the resultant long-range cooperativity depend on the ferritin shell packing, which, in turn, depends on protein sequence composition. Switching from the packing-on to the packing-off model reduces correlations by 35%–38% so that no allosteric network can be found. The influence of the side-chain packing on the allosteric networks explains the diversity in mechanisms of iron traffic suggested by experimental approaches.
Molecular-dynamics simulations of thin polyisoprene films confined between amorphous silica substrates
Authors: Guseva D. V. , Komarov P. V. , Lyulin Alexey V.
Published: March 2014

Constant temperature–constant pressure (NpT) molecular-dynamics computer simulations have been carried out for the united-atom model of a non-crosslinked (1,4) cis-polyisoprene (PI) melt confined between two amorphous, fully coordinated silica surfaces. The Lennard-Jones 12-6 potential was implemented to describe the polymer–silica interactions. The thickness H of the produced PI–silica film has been varied in a wide range, 1 < H/Rg < 8, where Rg is the individual PI chain radius of gyration measured under the imposed confinement. After a thorough equilibration, the PI film stratified structure and polymer segmental dynamics have been studied. The chain structure in the middle of the films resembles that in a corresponding bulk, but the polymer-density profile shows a pronounced ordering of the polymer segments in the vicinity of silica surfaces; this ordering disappears toward the film middles. Tremendous slowing down of the polymer segmental dynamics has been observed in the film surface layers, with the segmental relaxation more than 150 times slower as compared to that in a PI bulk. This effect increases with decreasing the polymer-film thickness. The segmental relaxation in the PI film middles shows additional relaxation process which is absent in a PI bulk. Even though there are fast relaxation processes in the film middle, its overall relaxation is slower as compared to that in a bulk sample. The interpretation of the results in terms of polymer glassy bridges has been discussed.
An extended Bretherton model for long Taylor bubbles at moderate capillary numbers
Authors: Klaseboer Evert , Gupta Raghvendra , Manica Rogerio
Published: March 2014

When (long) bubbles are transported in tubes containing a fluid, the presence of a thin film of fluid along the tube walls causes the velocity of the bubble to be different from the average fluid velocity. Bretherton [“The motion of long bubbles in tubes,” J. Fluid Mech. 10, 166 (1961)] derived a model to describe this phenomenon for pressure driven flows based on a lubrication approach coupled with surface deformation of the bubble. Bretherton found that the parameter governing the physics involved is the capillary number (Ca) which expresses the relationship between speed of the bubble, surface tension, and viscosity of the liquid. The results of Bretherton are here re-derived and analyzed in a slightly more perspicuous manner. Incorporating the condition that the bubble-film combination should fit inside the tube results in an expression very similar to the one found empirically by Aussillous and Quéré [“Quick deposition of a fluid on the wall of a tube,” Phys. Fluids 12, 2367 (2000)] of the Taylor [“Deposition of a viscous fluid on the wall of a tube,” J. Fluid Mech. 10, 161 (1961)] experimental data. Our expression is valid for Ca values up to Ca = 2.0, but approaches Bretherton's result for low values of Ca. The analysis is done in terms of the pressure buildup which originates from the interplay between surface tension and lubrication due to the thin layer of fluid near the tube wall.
Preparation and characterization of ferrite with Co substituted NiCuZn sheets application for 13.56 MHz radio frequency identification communication
Authors: Yan Shuoqing , Liu Weihu , Chen Zhongyan , Nie Yan , Wang Xian , Feng Zekun
Published: March 2014

The electromagnetic (EM) shielding sheets could be an effective solution to increase the detection distance of the RFID (Radio Frequency Identification) tags attached on metal. The eddy current induced on the metal surface can be reduced when a ferrite sheet sandwiched between RFID tag and metal. The magnetic spectra of Ni0.36Cu0.19Zn0.45Fe1.92O3.88 ferrite added with BiBSi-glass and CoO were investigated. It shows that the real part of permeability could reach above 150 while the imaginary part maintains below 2 at 13.56 MHz with 0.2 wt. % CoO and 0.4 wt. % BiBSi-glass doping content. The ferrites could be fabricated as EM shielding sheets by laminate process. The experimental results show that the doped ferrites could be a good candidate for EM shielding sheet. The final sheet size could be as large as 135 mm × 135 mm while the thickness is 0.1 mm and the density is above 5.0 g/cm3. By inserting the EM shielding sheet between the RFID antenna and metal surface, the improved communication performances are characterized and corresponding explanation is given.
Synchronous imaging of coherent plasma fluctuations
Authors: Haskey S. R. , Thapar N. , Blackwell B. D. , Howard J.
Published: March 2014

A new method for imaging high frequency plasma fluctuations is described. A phase locked loop and field programmable gate array are used to generate gating triggers for an intensified CCD camera. A reference signal from another diagnostic such as a magnetic probe ensures that the triggers are synchronous with the fluctuation being imaged. The synchronous imaging technique allows effective frame rates exceeding millions per second, good signal to noise through the accumulation of multiple exposures per frame, and produces high resolution images without generating excessive quantities of data. The technique can be used to image modes in the MHz range opening up the possibility of spectrally filtered high resolution imaging of MHD instabilities that produce sufficient light fluctuations. Some examples of projection images of plasma fluctuations on the H-1NF heliac obtained using this approach are presented here.
The theoretical ultimate magnetoelectric coefficients of magnetoelectric composites by optimization design
Authors: Wang H.-L. , Liu B.
Published: March 2014

This paper investigates what is the largest magnetoelectric (ME) coefficient of ME composites, and how to realize it. From the standpoint of energy conservation, a theoretical analysis is carried out on an imaginary lever structure consisting of a magnetostrictive phase, a piezoelectric phase, and a rigid lever. This structure is a generalization of various composite layouts for optimization on ME effect. The predicted theoretical ultimate ME coefficient plays a similar role as the efficiency of ideal heat engine in thermodynamics, and is used to evaluate the existing typical ME layouts, such as the parallel sandwiched layout and the serial layout. These two typical layouts exhibit ME coefficient much lower than the theoretical largest values, because in the general analysis the stress amplification ratio and the volume ratio can be optimized independently and freely, but in typical layouts they are dependent or fixed. To overcome this shortcoming and achieve the theoretical largest ME coefficient, a new design is presented. In addition, it is found that the most commonly used electric field ME coefficient can be designed to be infinitely large. We doubt the validity of this coefficient as a reasonable ME effect index and consider three more ME coefficients, namely the electric charge ME coefficient, the voltage ME coefficient, and the static electric energy ME coefficient. We note that the theoretical ultimate value of the static electric energy ME coefficient is finite and might be a more proper measure of ME effect.
Rotational motion of a thin axisymmetric disk in a low Reynolds number linear flow
Authors: Singh Vikram , Koch Donald L. , Subramanian Ganesh , Stroock Abraham D.
Published: March 2014

The motion of thin, torque-free axisymmetric rigid particles with fore-aft symmetry in low Reynolds number linear flows is investigated. The rotational motion of such a particle is fully determined by the effective aspect ratio (κe), defined as the aspect ratio of a spheroid having the same period of rotation as that of the particle. We determine the effective aspect ratio for a family of shapes given by, y(ρ) = κ(1 − ρ2)α where α is a positive parameter, ρ is the radial distance from the particle center in polar coordinates, y is half the thickness of the particle, κ is the aspect ratio of the particle defined as the ratio of the thickness (L) of the particle parallel to the axis of symmetry to its diameter (d) perpendicular to the axis of symmetry. This family includes an oblate spheroid (\documentclass[12pt]{minimal}\begin{document}$\alpha =\frac{1}{2}$\end{document}α=12) and the shape approaches a blunt circular cylinder shape as α → 0. For a thin particle, the effective aspect ratio scales like \documentclass[12pt]{minimal}\begin{document}$\smash{G_{A}^{\frac{1}{2}}}$\end{document}GA12, where GA is the torque non-dimensionalized by μγd3 acting on a particle held in a fixed alignment in a simple shear flow with its longer dimensions in the flow-vorticity plane. Here, μ is the fluid viscosity and γ is the shear rate. Starting with the integral representation of the Stokes flow, an analysis based on a matched asymptotic expansions approach is performed to determine the scaling of the torque acting on a stationary particle in simple shear flow with κ as the small parameter. Using boundary element method simulations, the exact torques are calculated and the scaling obtained from the analysis is verified. We find that there are two regions of interest that contribute to the torque, a flat outer region covering most of the disk area and a boundary layer region of large slope at the edge. For \documentclass[12pt]{minimal}\begin{document}$\alpha >\frac{1}{4}$\end{document}α>14, the torque is dominated by the stresses acting on the flat surface of the particle and is O(κ2) to the leading order. For these shapes, the effective aspect ratio scales like the aspect ratio of the particle. On the other hand, for \documentclass[12pt]{minimal}\begin{document}$\alpha \le \frac{1}{4}$\end{document}α≤14, the leading order torque contribution comes from the boundary layer region. To the leading order, the torque scales as O(κ2logκ) for \documentclass[12pt]{minimal}\begin{document}$\alpha =\frac{1}{4}$\end{document}α=14 and as \documentclass[12pt]{minimal}\begin{document}$O(\kappa ^\frac{3}{2(1-\alpha )})$\end{document}O(κ32(1−α)) for \documentclass[12pt]{minimal}\begin{document}$\alpha <\frac{1}{4}$\end{document}α<14. In general, a particle with a blunt edge is found to rotate faster than a particle of the same aspect ratio for which the slope of the edge varies slowly. The fastest rotating particle is identified to be a cylindrical disk for which κe = 1.12κ3/4.
Transport coefficients and entropy-scaling law in liquid iron up to Earth-core pressures
Authors: Cao Qi-Long , Wang Pan-Pan , Huang Duo-Hui , Yang Jun-Sheng , Wan Ming-Jie , Wang Fan-Hou
Published: March 2014

Molecular dynamics simulations were applied to study the structural and transport properties, including the pair distribution function, the structure factor, the pair correlation entropy, self-diffusion coefficient, and viscosity, of liquid iron under high temperature and high pressure conditions. Our calculated results reproduced experimentally determined structure factors of liquid iron, and the calculated self-diffusion coefficients and viscosity agree well with previous simulation results. We show that there is a moderate increase of self-diffusion coefficients and viscosity along the melting curve up to the Earth-core pressure. Furthermore, the temperature dependencies of the pair correlation entropy, self-diffusion, and viscosity under high pressure condition have been investigated. Our results suggest that the temperature dependence of the pair correlation entropy is well described by T−1 scaling, while the Arrhenius law well describes the temperature dependencies of self-diffusion coefficients and viscosity under high pressure. In particular, we find that the entropy-scaling laws, proposed by Rosenfeld [Phys. Rev. A 15, 2545 (1977)] and Dzugutov [Nature (London) 381, 137 (1996)] for self-diffusion coefficients and viscosity in liquid metals under ambient pressure, still hold well for liquid iron under high temperature and high pressure conditions. Using the entropy-scaling laws, we can obtain transport properties from structural properties under high pressure and high temperature conditions. The results provide a useful ingredient in understanding transport properties of planet's cores.
Crystal fields of porphyrins and phthalocyanines from polarization-dependent 2p-to-3d multiplets
Authors: Johnson Phillip S. , García-Lastra J. M. , Kennedy Colton K. , Jersett Nathan J. , Boukahil Idris , Himpsel F. J. , Cook Peter L.
Published: March 2014

Polarization-dependent X-ray absorption spectroscopy is combined with density functional calculations and atomic multiplet calculations to determine the crystal field parameters 10Dq, Ds, and Dt of transition metal phthalocyanines and octaethylporphyrins (Mn, Fe, Co, Ni). The polarization dependence facilitates the assignment of the multiplets in terms of in-plane and out-of-plane orbitals and avoids ambiguities. Crystal field values from density functional calculations provide starting values close to the optimum fit of the data. The resulting systematics of the crystal field can be used for optimizing electron-hole separation in dye-sensitized solar cells.
Multi-scale gyrokinetic simulation of Alcator C-Mod tokamak discharges
Authors: Howard N. T. , White A. E. , Greenwald M. , Holland C. , Candy J.
Published: March 2014

Alcator C-Mod tokamak discharges have been studied with nonlinear gyrokinetic simulation simultaneously spanning both ion and electron spatiotemporal scales. These multi-scale simulations utilized the gyrokinetic model implemented by GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] and the approximation of reduced electron mass (μ = (mD/me).5 = 20.0) to qualitatively study a pair of Alcator C-Mod discharges: a low-power discharge, previously demonstrated (using realistic mass, ion-scale simulation) to display an under-prediction of the electron heat flux and a high-power discharge displaying agreement with both ion and electron heat flux channels [N. T. Howard et al., Nucl. Fusion 53, 123011 (2013)]. These multi-scale simulations demonstrate the importance of electron-scale turbulence in the core of conventional tokamak discharges and suggest it is a viable candidate for explaining the observed under-prediction of electron heat flux. In this paper, we investigate the coupling of turbulence at the ion (kθρs∼O(1.0)) and electron (kθρe∼O(1.0)) scales for experimental plasma conditions both exhibiting strong (high-power) and marginally stable (low-power) low-k (kθρs < 1.0) turbulence. It is found that reduced mass simulation of the plasma exhibiting marginally stable low-k turbulence fails to provide even qualitative insight into the turbulence present in the realistic plasma conditions. In contrast, multi-scale simulation of the plasma condition exhibiting strong turbulence provides valuable insight into the coupling of the ion and electron scales.
Poole-Frenkel effect on electrical characterization of Al-doped ZnO films deposited on p-type GaN
Authors: Huang Bohr-Ran , Liao Chung-Chi , Ke Wen-Cheng , Chang Yuan-Ching , Huang Hao-Ping , Chen Nai-Chuan
Published: March 2014

This paper presents the electrical properties of Al-doped ZnO (AZO) films directly grown on two types of p-type GaN thin films. The low-pressure p-GaN thin films (LP-p-GaN) exhibited structural properties of high-density edge-type threading dislocations (TDs) and compensated defects (i.e., nitrogen vacancy). Compared with high-pressure p-GaN thin films (HP-p-GaN), X-ray photoemission spectroscopy of Ga 3d core levels indicated that the surface Fermi-level shifted toward the higher binding-energy side by approximately 0.7 eV. The high-density edge-type TDs and compensated defects enabled surface Fermi-level shifting above the intrinsic Fermi-level, causing the surface of LP-p-GaN thin films to invert to n-type semiconductor. A highly nonlinear increase in leakage current regarding reverse-bias voltage was observed for AZO/LP-p-GaN. The theoretical fits for the reverse-bias voltage region indicated that the field-assisted thermal ionization of carriers from defect associated traps, which is known as the Poole-Frenkel effect, dominated the I-V behavior of AZO/LP-p-GaN. The fitting result estimated the trap energy level at 0.62 eV below the conduction band edge. In addition, the optical band gap increased from 3.50 eV for as-deposited AZO films to 3.62 eV for 300 °C annealed AZO films because of the increased carrier concentration. The increasing Fermi-level of the 300 °C annealed AZO films enabled the carrier transport to move across the interface into the LP-p-GaN thin films without any thermal activated energy. Thus, the Ohmic behavior of AZO contact can be achieved directly on the low-pressure p-GaN films at room temperature.
How much improvement in thermoelectric performance can come from reducing thermal conductivity?
Authors: Gaultois Michael W. , Sparks Taylor D.
Published: March 2014

Large improvements in the performance of thermoelectric materials have come from designing materials with reduced thermal conductivity. Yet as the thermal conductivity of some materials now approaches their amorphous limit, it is unclear if microstructure engineering can further improve thermoelectric performance in these cases. In this contribution, we use large data sets to examine 300 compositions in 11 families of thermoelectric materials and present a type of plot that quickly reveals the maximum possible zT that can be achieved by reducing the thermal conductivity. This plot allows researchers to quickly distinguish materials where the thermal conductivity has been optimized from those where improvement can be made. Moreover, through these large data sets we examine structure-property relationships to identify methods that decrease thermal conductivity and improve thermoelectric performance. We validate, with the data, that increasing (i) the volume of a unit cell and/or (ii) the number of atoms in the unit cell decreases the thermal conductivity of many classes of materials, without changing the electrical resistivity.
23 bits optical sensor based on nonvolatile organic memory transistor
Authors: Ren Xiaochen , Chan Paddy K. L.
Published: March 2014

Polymer electret transistor memory device has stable charge storage and memory properties. Here, we combine a large band gap organic semiconductor dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene with the polystyrene electret to form an optical sensor with memory effect. The blue light combined with programming bias leads to a positive threshold voltage shift for more than 100 V while the drain-source current shows a variation of seven orders of magnitude. The dynamic range of current device is up to 23 bits and the photo responsivity is 420 A W−1. The optically programmed transistor can be directly used for high-resolution optical sensor and multi-level data storage applications.